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Allied Chemical and Dye Corporation in 1947, it was a decade later when ..... In India Acrylonitrile only produced by Indian Petrochemicals Corporation Limited. (IPCL) ...... copper, asbestos-cement, ceramic, plastic, rubber, reinforced concrete.

      

                                                   

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ABSTRACT 7KHSURMHFWUHSRUWIRUµ$FU\ORQLWULOH¶SUHVHQWHGKHUHLQLVLQWHQGHGWRFRYHUWKHRUHWLFDO and practical principles associated with manufacture of Acrylonitrile and application of such principles to a commercial plant scale. 7KH ILUVW FKDSWHU µ,QWURGXFWLRQ¶ GLVFXVVHV LQ EULHI WKH KLVWRU\ DQG GHYHORSPHQW RI Acrylonitrile and its production. Detailed list of uses of Acrylonitrile as product and Acetonitrile as byproduct are also included. It includes import and export data for Acrylonitrile. The chapter contains manufacturer in India and worldwide, their installed capacities and present production rates. 7KH FKDSWHU µ/LWHUDWXUH VXUYH\¶ LQFOXGHV WKH W\SHV RI OLWHUDWXUH LH LQIRUPDWLRQ sources that were referred in preparation of this report. A detailed review of information regarding Acrylonitrile is presented. µ3URFHVVVHOHFWLRQ¶FKDSWHUFRYHUVYDULRXVDYDLODEOHSURFHVVHVXVHGIRUSURGXFWLRQRI Acrylonitrile on a worldwide basis. The various processes are used are described thereafter. The capacity selection and justification for it are presented in this chapter. A process description of Sohio process i.e. ammoxidation of propylene in fluidized bed reactor is followed by detail description include in next chapter. 7KH FKDSWHU RQ µ0DWHULDO %DODQFH¶ FRYers an overall material balance for 70000 MTPD Acrylonitrile plant as well as equipment wise material balance. 7KH FKDSWHU RQ µ(QHUJ\ %DODQFH¶ LQFOXGHV WKH HQWKDOS\ FKDQJHV DVVRFLDWHG ZLWK equipments, cooling or heating requirements and loads on condensers and reboilers of columns. 7KH FKDSWHU RQ µGHVLJQ RI PDMRU HTXLSPHQWV¶ FRYHUV GHWDLO SURFHVV GHVLJQ DQG mechanical design of the Fluidized bed reactor and HCN column. The Fluidized bed reactor and HCN column. The Fluidized bed reactor also includes the design of bubbling fluidized bed model. The specifications for auxiliary equipments mention in next chapter. 7KH µ8WLOLW\ UHTXLUHPHQWV¶ FKDSWHU LQFOXGHV WKH FRROLQJ ZDWHU UHIULJHUDQW VWHDP power, air, nitrogen and other utility requirements for the process in consideration. 1

7KHµ(QYLURQPHQWDODQG6DIHW\&RQVLGHUDWLRQ¶FKDSWHUGLVFXVVHVSROOXWLRQSUREOHPV as well as safety data and measures for Acrylonitrile plant. It includes safety measures carry out in Acrylonitrile plant. It also includes biodegradation of waste FRQWDLQORZF\DQLGH7KHµ0DWHULDOVRIFRQVWUXFWLRQ¶FKDSWHUSUHVHQWVWKHPDWHULDOVRI construction for various equipments. 7KH µ,QVWUXPHQWDWLRQ DQG 3URFHVV &RQWURO¶ FKDSWHU LQFOXGHV PDMRU SURFHVV FRQWURO techniques and instruments along with a P & I diagram. In which process control techniques and instruments provision on reactor is also mention with its significance. Project & product costs, return of investment and pay-out periods have been HVWLPDWHGSUHVHQWHGLQµ(FRQRPLF$QDO\VLV¶ A comSOHWHOLVWRIFLWHGUHIHUHQFHLVSUHVHQWHGLQWKHµ5HIHUHQFH¶FKDSWHU At last, properties of Acrylonitrile, various data related to Acrylonitrile and $FU\ORQLWULOHSODQWDUHLQFOXGHGLQµ$SSHQGLFHV¶

2

CONTENTS

Abstract

01

Contents

03

List of Table

07

List of Figure

08

Nomenclature & Symbols

09

Sr. Chapter Title No. 1 1 Introduction 1.1 Introduction 1.2 History 2 2 Market Survey 2.1 Uses of Acrylonitrile 2.2 Uses of Acetonitrile 2.3 Current installed capacity 2.4 Import & export position 3 3 Physical & Chemical Properties 3.1 Physical Properties 3.2 Chemical Properties 4 4 Literature Survey 4.1 Literature Survey 4.2 Acrylonitrile & Sohio process 4.3 Sohio Process Research & Development 4.4 Reaction Kinetics 4.5 Catalyst Development 4.6 Catalyst mechanism 4.7 Synthesis of method 4.8 Economics ± Acrylonitrile 5 5 Process Selection 5.1 Basic manufacturing process 5.2 Selection of best process 5.3 Selection capacity 6 6 Thermodynamics & kinetics 6.1Process selection 6.2 Revamps of Acrylonitrile plant 3

Page No. 11 11 12 15 15 20 21 22 26 26 29 31 31 32 33 35 36 37 37 38 41 41 51 53 54 54 62

7

7

8

8

9

9

10

10

6.3Auxiliary Chemicals added

62

Material Balance 7.1 Basis 7.2 Catalyst performance 7.3 Molecular weight 7.4 Reactor 7.5 Quench column 7.6 Absorber 7.7 Recovery column &Decanter 7.8 Aceto column 7.9 HCN column 7.10 Product column Energy Balance 8.1 Preheating of reactor 8.2 Reactor 8.3 Cooler 8.4 Quench column 8.5 Around after cooler 8.6 Heat absorbers and heat exchangers 8.7 Recovery column 8.8 Decanter 8.9 Aceto Stripper 8.10 HCN Column 8.11 ACN column Design of Equipments 9.1 Fluidized Bed Reactor 9.2 Distillation Column Process Control & Instrumentation 10.1 Role of P& ID 10.2 Process measurement 10.3 Temperature Control 10.4 Pressure Control 10.5 Level Control 10.6 Flow Control 10.7 Alarms And Safety Trips And Interlocks 10.8 Instrumentation And Process Control For Acrylonitrile Reactor 10.9 Instrumentation And Process Control For Other

65 65 65 66 67 70 71 72 73 73 74 75 75 75 78 79 81 82 84 86 87 88 89 90 90 95 103 103 104 105 106 106 106 107 107

4

108

Equipments 11

11

12

12

13

13

14

14

Safety and pollution control 11.1 Safety And Pollution Control 11.2 Chemical Hazards 11.3 Fire And Explosion Hazard 11.4 Air And Land Pollution 11.5 Safety In Plant 11.6 Concept of safer side 11.7 Prevention & control of hazards in ACN plant 11.8 Acetonitrile 11.9 ACETONITRILE: Safety Data Sheet 11.10 Hydrogen Cyanide 11.11 Ammonia 11.12 General Safety Aspects In Chemical Plant: 11.13(Effluent Treatment ) Plant location & layout 12.1 Selection of plant location 12.2 Primary factors for plant location 12.3 Specific factors for plant location 12.4 Plant layout Cost Estimation 13.1 Factors affecting production & investment cost 13.2 Capital investment 13.3 Direct cost 13.4 Indirect cost 13.5 Costing of plants 13.6 Profit Analysis

110 110 110 110 111 111 112 113 117 123 124 125 126 133 137 137 137 139 141 144 144 145 145 146 148 152

Utilities 14.1 Utilities 14.2 Steam systems 14.3 Fuel system 14.4 Water system 14.5 Brine coolant system 14.6 Air system 14.7 Nitrogen system 14.8 Electricity 14.9 Steam generating system

153 153 153 154 154 155 156 157 157 157

5

15

15

16

Auxiliary Equipments 15.1 Column 15.2 Heat Exchangers 15.3 Tanks Summary

160 160 161 161 162

16 17

17

References

163

18

18

Appendices 18.1 Appendices No. 1 18.2 Appendices No. 2 18.3 Appendices No. 3

166 166 168 170

6

LIST OF TABLES Table No. 2.1 2.2 2.3 2.4 2.5 2.6 2.7 3.1 3.2 3.3 3.4 3.5 7.1 7.2 7.3 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 9.1 10.1 11.1 13.1 13.2 13.3 13.4 14.1

Description of Tables Levels of residual acrylonitrile found in various products ,QGLD¶V3HUVSHFWLYH Uses of acrylonitrile U.S and Europe Producers of Acrylonitrile Estimated U.S production of acrylonitrile Industries in India import acrylonitrile.(in 1983) Historical data Physical Properties of Acrylonitrile Thermodynamic Data: Solubilities of Acrylonitrile in Water: Azeotrope of acrylonitrile: Acrylonitrile vapor Pressure over Aq. solutions at 250C Molecular weight in kg / kgmole Material balance over Reactor Material balance over Quench Column: Components and its properties Components and its Heat properties Enthalpy out with products Enthalpy out with gases Enthalpy out with gases [at top] Enthalpy out with the mixture Enthalpy out with unabsorbed gases from top Enthalpy out with bottom stream Enthalpy out with Distillate: [DHD] Components and their mole fraction Enthalpy in Decanter X-Y composition Temperature ranges for certain instruments: COD/BOD table Purchase equipment cost (PEC) Direct Production cost Labor and production supervision Product selling cost Utility Requirement:

7

Page No. 18 19 19 21 22 23 25 26 27 27 28 28 66 69 71 75 76 77 78 80 82 83 83 85 85 86 96 105 134 148 150 150 152 158

LIST OF FIGURES Figure No. 5.1 5.2 5.3 9.1 18.1

Description of Figures Acrylonitrile by Sohio Process Acrylonitrile by Ethylene Cyanohydrin route Acrylonitrile by Acetylene-HCN route Macabe-Theile method (X-Y plot) Safety Symbol for Acrylonitrile

8

Page No. 42 45 47 97 171

NOMENCLATURES & SYMBOLS

W

= Weight flow of shell side fluid, (kg/hr)

C

= Heat capacity of shell side fluid, (kJ/kg °C)

µ

= Shell side fluid viscosity, (kg/m.hr)

K

= Thermal conductivity of hot fluid, (kJ/m hr°C)

Rd1, Rd2

= Dirt factor, (hr ft2°F/Btu)

W

= Weight flow of tube side fluid, (kg/hr)

c

= Heat capacity of tube side fluid, (kJ/kg °C)

µ

= tube side fluid viscosity, (kg/m.hr)

k

= Thermal conductivity of cold fluid, (kJ/m hr°C)

LMTD

= Log mean temperature difference, (°C)

R

= Temperature group (dimensionless)

S = s1

= Temperature group (dimensionless)

T1

= Shell side inlet temperature, (°C)

T2

= Shell side outlet temperature, (°C)

t1

= tube side inlet temperature, (°C)

t2

= tube side outlet temperature, (°C)

¨7

= Temperature differences of table, (°C)

IDs = ID

= Internal diameter of shell, (m)

Nt

= Number of tubes

D

= Inside diameter of tubes, (m)

Lt

= Length of tubes, (m)

PT

= Pitch, (m)

Qs

= Shell side heat flow, (kJ/hr)

Qt

= Tube side heat flow, (Btu/hr)

Ft

= Temperature difference factor (dimensionless)

Ta

= Average temperature of hot fluid, (°C)

Tb

= Average temperature of cold fluid, (°C)

¨W

= True temperature difference, (°C) 9

as

= Area of Shell, (m2)

C'

= Clearance,(m)

B

= Baffle spacing, (m)

De

= Equivalent diameter of heat transfer for shell side, (m)

Gs

= Mass velocity, (kg/hr m2)

Res

= Reynolds number for heat transfer (dimensionless)

jH

= Factor for heat transfer (dimensionless)

Øs

= Viscosity ratio (µ/µ w) (dimensionless)

Øt

=Viscosity ratio (µ/µ w) (dimensionless)

ho

= Heat transfer co-efficient for outside fluid, (kJ/m2 hr°C)

at¶

=Area of a tube, (m)

n

= Number of passes

Gt

= Mass velocity, (kg/hr m2)

at

= Area of tube side, (m2)

V

= Velocity, (m/s)

Ro

= Density of cold fluid, (kg/m3)

Ret

= Reynolds number of tube side for heat transfer (dimensionless)

hi

= Heat transfer co-efficient for outside fluid, (kJ/m2 hr°C)

ID

= Inside diameter of tube, (m)

OD

= Outside diameter of tube, (m)

hi o

= Value of hi when referred to tube side diameter, (kJ/m2 hr°C)

Uc

= Clean overall heat transfer co-efficient, (kJ/m2 hr°C)

Ud

= Designed overall heat transfer co-efficient, (kJ/m2 hr°C)

A

= Heat transfer surface, (m2 )

D¶¶

= External surface per linear foot, (m2 )

f1 , f2

= friction factor (dimensionless)

De1

= Equivalent diameter, (m)

S1

= specific gravity (dimensionless)

¨3s

= Allowable pressure drop for shell side, (psi)

¨3t

= Allowable pressure drop for tube side, (psi) 10

CHAPTER-1: INTRODUCTION

1.1 INTRODUCTION Chemical Name: Acrylonitrile

Molecular Formula: CH2CHCN Structural Formula:

Synonyms: ACN Vinyl cyanide Acrylic nitrile 2 ± propenenitrile Propenoic acid nitrile Propylene nitrile Acrylic acid nitrile Cyanoethylene International Classification: UN No.

1093

CAS Reg No.

107-13-1

EINECS No.

203-466-5

EC No.

608-003-00-4

STCC

4906420 11

HI (Kemler Code)

33

HS Code

2926 10 00

Description

Flammable Liquid, Toxic substance.

WGK

3 (highly polluting substance)

Packing group

1

Emergence action code

3WE

Poison Class

1* (carcinogenic, mutagenic)

Storage Class (VCI)

3 A (Flammable liquid materials)

1.2 HISTORY In 1983, the French Chemist, CH. MOUREAU, first prepared Acrylonitrile by dehydrating either acrylamide or ethylene Cyanohydrin with phosphorous pentoxides. However, no significant technical or commercial applications were discovered for acrylonitrile until the late 1930s. Interest in acrylonitrile first developed when I.G. Farben industries introduced a synthetic rubber, Buna N, based on a copolymer of butadiene and acrylonitrile into Germany. This synthetic rubber was highly resistant to swelling in gasoline, oils and other non polar solvents. At about the some time research began in United States on similar copolymers termed GR-A, NBR or nitrile rubber. During Second World War, acrylonitrile containing polymers was developed in the US and West Germany due to its resistance to oils and lack of access to natural rubber. Projects concerning acrylonitrile containing polymers received special support during Second World War because of obvious strategic importance, thus establishing acrylonitrile as a monomer with commercial significance. Since that time the dramatic increase in demand for acrylonitrile has been attributed not to nitrile rubber but largely to acrylic fibers, first introduced commercially in 1950 by Du Pont under the trademark Orlon based on ethylene oxide and Hydrogen cyanide i.e. from ethylene Cyanohydrin,. Spurred efforts to develop improved process technology for acrylonitrile manufacture to meet the growing market. Therefore, it found numerous other applications as monomer, co monomer, and intermediate for fibers, resins, thermoplastic and elastomers. Other significant uses 12

are as an intermediate for organic synthesis, most notably for producing adiponitrile and acrylamide. This wide range of applications and successful improvements in production techniques were the essential reasons for the dramatic expansion in acrylonitrile production. Acrylonitrile is among the top 50 Chemical produced in the United States as a result of the tremendous growth in its use as a starting for a wide range of chemical and polymer products. Today nearly all acrylonitrile is produced by Ammoxidation of propene. Four major company groups, Sohio, Nitto, Eni Chem. /UOP & BP Chemicals/Ugine have developed Ammoxidation processes of commercial importance. Although the first report of the preparation of acrylonitrile from propene occurred in a patent by the Allied Chemical and Dye Corporation in 1947, it was a decade later when Standard Oil of Ohio (Sohio) developed the first commercially viable more effective catalysts having economically interesting selectivities for this process and it is known as Sohio Process. Today, all of the United States capacity and approximately 90% of world capacity for acrylonitrile is based on the Sohio Process. Sohio, now BP chemicals, is WKHZRUOG¶VODUJHVWOLFHQVRUZLWKLQWKHODWHVRIWRWDl installed capacity. Other development Related to acrylonitrile are as follows: The attempt to react olefins with ammonia is by no means new. In 1934 reference was made by Elllis to the reaction of ethylene and ammonia at 450 oC in the presence of zinc sulphate on silica gel to give Acetonitrile. CH2 = CH2 + NH3

CH3CN + 2H2

Sinclair Refining Company carried out a programmed of work on the reaction of olefins and ammonia after the Second World War. Such reactions were carried out at high pressure and about 350o C.in the presence of hydrogenation catalysts such as cobalt. Products from ethylene, propylene, and the n-butenes included the straight chain amines and nitriles; from propylene, acrylonitrile was obtained but in low yield. CH3CH:CH2 + NH3

CH2 = CHCN + 3H2

13

Socony Vacuum Oil Company (now Mobil Oil Co.) also examined this field using higher temperatures, lower pressures and a less active hydrogenation catalyst. Acetonitrile was the main product from most olefins. Interest in the specific synthesis of acetonitrile has waned with the availability of by-product acetonitrile from the newer acrylonitrile syntheses. Acetonitrile is assuming an increasing significance as a solvent for extractive distillation. Approximately stoichiometric quantities of propylene, ammonia and oxygen (as air) are introduced into a fluidized catalytic reactor at 1-3 atm and 400-500o C. with a contact time of a few seconds, as a once-through operation. The reactor effluent is scrubbed with water in a recovery tower to remove the soluble organic products as an aqueous solution. The solution is taken to a product separator providing a wet acrylonitrile overhead product which is dried and purified by azeotropic and conventional distillation. The bottom product from the separator is wet acetonitrile which is concentrated, dried and purified by distillation. The catalyst is understood to be bismuth phosphomolybate. Yields, per pound of propylene feed, have been quoted as follows: acrylonitrile 0.13lb.27 it is understood that this process now uses a different catalyst not including bismuth, and possibly based on spent uranium. The SNAM process for propylene ammoxidation indicates a reactor temperature of 520 OC., molar rations 1 propylene 1.1 ammonia, 8 air and 20 steam. With a catalyst containing 1.1 per cent vanadium. Extractive distillation (using water and acetophenone) is used to assist in the separation acrylonitrile from acrylonitrile. 4CH3CH = CH2 + 6NO

4CH2 = CHCN + N2 + 6H2O

The nitric oxide may be regarded as a product of ammonia oxidation. The du Pont process is carried out at about 700oC in the presence of a supported silver catalyst. Other reaction of olefins with nitrogen compounds have been overshadowed by the massive developments in the manufacture of acrylonitrile, but are not without interest.

14

CHAPTER-2: MARKET SURVEY

2.1 USES OF ACRYLONITRILE For Doing Market Survey we need to find uses of acrylonitrile. Acrylonitrile is a key monomer for various polymeric consumer products. A such, it is not used directly in any and use; however it is building monomer for below given polymeric material. 2.1.1 Fibers: Acrylonitrile most important application is for the production of polymer for textile fibers. Acrylic textile fibers are by far the largest end use products for ACN. Acrylic fibers always contain a Comonomer such as methyl acrylates. Fiber containing 85% wt of more ACN are usually referred to as acrylics whereas fibers containing 35 to 80 % ACN are termed modacrylics. These fibers are used primarily for the manufacture of apparel, including sweaters, fleece wear and sportswear as well as for home furnishings, including carpets, upholstery and draperies. Demand is largely subject to turns in the fashion industry. Acrylic fibers consume about 65% of the ACN produced worldwide. The familiar trade names of acrylic fibers are Orlon, acrilan, Courtelle. 2.1.2 Resins: The production of acrylonitrile butadiene styrene (ABS) and styrene-acrylonitrile (SAN) resins consumes the second largest quantity ACN and styrene onto polybutadiene or a styrene butadiene copolymer. ABS is the most widely used engineering (i.e. metal replacing) plastic. It is a two phase polymer system, with the electrometric butadiene ± acrylonitrile copolymer dispersed in a rigid styrene ± acrylonitrile matrix. ABS resins contain about 25% ACN and are characterized by their chemical resistance, mechanical strength and are RI PDQXIDFWXUH &RQVXPSWLRQ RI $%6 UHVLQV LQFUHDVHG VLJQLILFDQWO\ LQ ¶V ZLWK its growing application as a specialty performance polymer in construction, automotive, machine and appliance applications. Opportunities still exist for ABS resins to replace more traditional material for packaging, building, and automotive components. 15

SAN resins typically contain 25-30% ACN. Because of their high clarity, they can be used primarily as a substitute for glass in drinking cups and tumblers, automobile instrument panels and instrument lenses. Together, ABS and SAN resins account for about 20% of domestic acrylonitrile consumption. 2.1.3 Intermediated for polymers: Because of its reactivity, acrylonitrile can be used as a chemical intermediate. Examples are acrylic acid and acrylamide by hydrolysis, adiponitrile, a nylon intermediate, by electrolytic coupling and amines by cyanoethylation. The largest increase among the end-uses for ACN over the past 10 years has come from chemical intermediates adiponitrile and acrylamide. This has grown to become the third largest outlet of ACN. Adiponitrile is used by Monsanto as a precursor for hexamethylenediamine (HMDA, C6H16N2) and is made by a proprietary ACN electrohydrodimerization process. HMDA is used exclusively for the manufacture of nulon-6, 6. The growth of this ACN in recent years stems largely form replacement of adipic acid (C6H10O4) with ACN in HMDA production rather than from a significant increase in nylon6, 6 demand. A non electrochemical catalytic route has also been developed for ACN dimerization to adiponitrile. This technology, if it becomes commercial, can provide additional replacement opportunity for ACN in nylon manufacture. Acrylamide is produced commercially by heterogeneous copper catalyzed hydration of ACN. It is used primarily in the form of a polymer, polyacrylamide, in the paper and pulp industry and in waste water treatment as flocculants to separate solid material from waste water streams. Other applications include mineral processing, coal processing and enhanced oil recovery in which polyacrylamide solutions were found effective for displacing oil from rock. Other growth markets for acrylamide are in binders, adhesive and absorbents. 2.1.4 Rubber: Nitrile rubber, the original driving force behind ACN production, have taken a less significant place as end-use products Nitrile rubber consists of butadiene ACN cop0olymers with an ACN content of 15-45%. Butadiene ± acrylonitrile rubber was 16

developed in Germany prior to World War II and is still used today. . They find extensive industrial application because of its excellent resistance to oil and chemicals, its good flexibility at low temperatures, high abrasions and heat resistance (up to 1200C) and good mechanical properties. In addition to the traditional applications of nitrile rubber for hoses, gaskets, seals and oil well equipment, new applications have merged with the development of nitrile rubber blends with PVC. These blends combine the chemical resistance and low temperature flexibility characteristics of nitrile rubber with the stability and ozone resistance of PVC. This has greatly expanded the use of nitrile rubber in outdoor applications for hoses, belts and cable jackets, where ozone resistance is necessary. 2.1.5 Specialty application: Some ACN copolymers have found specialty applications where good gas barrier properties are required along with strength and high impact resistance. Examples of WKHVH DUH %3 FKHPLFDOV¶ %DUH[  $&1 PHWK\O Acrylate butadiene copolymer. These barrier resins compact directly in the alcoholic and other beverage bottle market with traditional glass and metal containers as well as with polyethylene terephthalate [PET] and poly vinyl chloride [PVC] in the beverage bottle market. Other applications include food, agro-chemicals and medical packaging. Total ACN consumption for barrier resins application is small, consuming less than about 1% of the total ACN production. The acrylonitrile content of containers fabricated from acrylonitrile copolymers and the possible migration of acrylonitrile into foods and beverages have been reviewed. The U.S. Federal Drug Administration declared acrylonitrile to be an indirect food additive and banned its use in beverage containers and other food-packaging applications in the USA in September, 1977. The Environmental Protection Agency(EPA) and the German MAK commission has classified acrylonitrile to be a human carcinogen The Canada Food and Drugs Act and Regulations (1982) prohibit the sale of any food in packaging containing acrylonitrile, such that the compound may pass into the food. 17

A growing specialty application for ACN is in the manufacture of carbon fibers. They are produced by pyrolysis of or oriented PAN fibers and are used to reinforce composites for high performance application in the air craft, defense, and aerospace industries. These applications include rocket engine nozzles, rocket nose cones, and structural components for aircraft and orbital vehicles where light weight and high strength are needed. Other small specialty application of ACN are in the production of fatty amines, ion exchange resins, and fatty amines use in cosmetics, adhesive, corrosion inhibitors and water treatment resins. Examples of these amines include 2-acrylamido-2methylpropanesulfonic acid (C7H13NSO4), 3-methoxypropionitrile (C4H7NO) and 3methoxypropylamine (C4H11NO). Other monomers, for example vinyl chloride, vinylidene chloride, vinyl acetate and acrylates, will copolymerize with acrylonitrile to form resins used in paints, surface coating and packaging. Acrylonitrile is used in manufacturing of Pesticides. In a mixture with carbon tetrachloride, acrylonitrile has also been used as a fumigant for tobacco and for flour milling and bakery equipment. Table 2.1 shows the levels of residual acrylonitrile in several polymers, some acrylonitrile derivatives and products fumigated with acrylonitrile (US Consumer Product Safety Commission). Table 2.1: Levels of residual acrylonitrile found in various products Product

Acrylonitrile content

Acrylic and modacrylics fibres

1 mg/kg

Acrylonitrile-butadiene-styrene resins

30-50 mg/kg

Styrene-acrylonitrile resins

15 mg/kg

Nitrile rubber and latex material

0-750 mg/kg

Acrylamide

25-50 mg/kg

Polyether polymer polyols

100-300 mg/kg

18

Table 2.2: Indian Perspective The trend in consumption of various end products as the percentage of total ACN produced and import in India as shown below. USE

CONSUMPTION (% of ACN produced)

Acrylic fibers

65

ABA/SAN resins

15

Adiponitrile/ acrylamide

12

Nitrile rubber

4

Other

4

Table 2.3: shows the use patterns of acrylonitrile and its products in the USA and Western Europe Product

% of acrylonitrile

% of product

production

Acrylic

and

USA

W. Europe

48

68

82 - clothing and home furnishings, 18 -

modacrylic fibers Acrylonitrile-

export 21

15

88 - pipe fittings, automotive vehicle

Butadiene-styrene

components, 12 - automobile

and Acrylonitrile-

instrument panels, household items etc.

styrene resins Adiponitrile

12

--

mainly hexamethylenediamine

Other products

19

17

21 - nitrile elastomers, 21 ± acrylamide, 16 - barrier resins, 42 polyether polymer

19

2.2 USES OF ACRYLONITRILE Being a volatile highly polar solvent, acrylonitrile finds its greatest use as an extracting fluid for fatty acids and animal and vegetable oils. Acrylonitrile has been widely used as an extractive distillation solvent in the petrochemical industry for separating olefin-diolefin mixtures and for C4-hydrocarbons. When Acrylonitrile is used in this way, recycling is effected by water dilution of the extract and condensate with subsequent phase separation, after which the Acrylonitrile is Azeotrope from the aqueous phase. Acrylonitrile has been used as a solvent for polymer spinning and casting because of the combination of high solubility and desirable intermediate volatility. It is also used as a solvent for isolating components from crude products such as crude wool resin. Acrylonitrile is used as a common laboratory solvent for recrystallizing various chemicals and is widely used as a solvent in HPLC analysis. Acrylonitrile is also used in biotechnology research as a solvent in the synthesis of DNA and peptide sequencing (Borman,1990). Acrylonitrile can be used to remove tars, phenols and colouring matter from petroleum hydrocarbons that are not soluble in Acrylonitrile. Acrylonitrile is also used as a starting material for the synthesis of many chemicals such as acetophenone, alpha-naphthyl acetic acid, thiamine and acetomidine (Hawley, 1971). Main use patterns of Acrylonitrile ¾ Extraction of fatty acids and animal and vegetable oils ¾ Extraction of unsaturated petroleum hydrocarbons ¾ Solvent for polymer spinning and casting ¾ Moulding of plastics ¾ Removal of tars, phenols and coloring matter from petroleum hydrocarbons ¾ Purification of wool resin ¾ Recrystallization of steroids ¾ Starting material for synthesis of chemicals ¾ Solvent in DNA synthesis and peptide sequencing ¾ Medium for promoting reactions ¾ Solvent in non-aqueous titrations 20

¾ Non-aqueous solvent for inorganic salts ¾ High-pressure liquid chromatographic analysis ¾ Catalyst and component of transition-metal complex catalysts ¾ Extraction and refining of copper, Stabilizer for chlorinated solvents ¾ Perfume manufacture, Pharmaceutical solvents 2.3 CURRENT INSTALLED CAPACITY Acrylonitrile is a large-volume commodity chemical. Worldwide capacity is about 5.7 million metric tons. Capacity compared with consumption is in surplus in North America and in deficit in Asia. World production in 2000 was estimated at about 4.6 million metric tons. In India: In India Acrylonitrile only produced by Indian Petrochemicals Corporation Limited (IPCL), Baroda complex by Sohio Process having capacity of 30000 tons per annum which consumed in Acrylates plant of IPCL itself. In USA: By 2001, the demand for acrylonitrile is expected to be 3.8 billion pounds. Following is a list of the dominant producers of acrylonitrile in the United States. Table 2.4: Producers of acrylonitrile and their capacities Producer

Location

1997 Capacity*

1994 Capacity*

BP Chemicals,

Green Lake, TX

1,000

700

BP Chemicals,

Lima, OH

500

500

Cytec Industries,

Avondale, LA

475

320

DuPont,

Beaumont, TX

385

380

Solutia Monsanto),

Alvin, Tex.

500

480

City, 700

700

Sterling Chemicals, Texas TX

* millions of pounds of acrylonitrile produced per year (Source: Mannsville and other websites) Sterling Chemicals' 750-million-pound-per-year acrylonitrile plant at Texas City, Tex. has been idled since February 2001 because of poor profitability. 21

Monsanto spun-off its industrial chemicals operations as Solutia, in 1997. In late 2000, Solutia brought a new 550 million-pound per year plant on stream in Alvin, raising the site's nameplate capacity to more than 1 billion pounds. The plant's output is shared with Asahi and Bayer, both of which have equity in the facility. Amoco merged with British Petroleum to become BP Amoco in 1998. In July 2000, BP Amoco Chemicals reverted to the name BP Chemicals after BP Amoco decided to adopt a new unified global brand, centered on the name BP. The new name embraces British Petroleum, Amoco, Arco and Burmah Castrol, all acquired by BP. Table 2.5: Estimated U.S. production and capacity of Acrylonitrile (Millions of Pounds) Year

1991

1992

1993

1994

1996

Capacity

3,080

3,080

3,080

3,080

3,200

Production

2,642

2,823

2,504

2,926

N/A

Exports

1,300

1,365

1,020

1,450

N/A

Demand

1,342

1,458

1,484

1,476

1,550

(Source: USITC and other websites) Demand for acrylonitrile is expected to grow at an average annual rate of 2 to 3 percent after the 1990/1991 market slowdown. It is estimated that production was roughly 2,926 million pounds in. Exports were expected to increase from 1,020 million pounds in 1993 to 1,450 million pounds in 1994. U.S. capacity greatly exceeds domestic demand. About 40 percent of U.S. production of acrylonitrile was exported in 1993. Increasing worldwide capacity for acrylonitrile production may limit U.S. exports in the future. 2.4 IMPORT / EXPORT POSITION The demand for Acrylonitrile in the world is growing. The Asian demand currently represents about half of the worldwide Acrylonitrile demand of some 5,000,000 tons per year, and its growth is expected to continue. The export market for acrylonitrile continues to be driven by strong demand from Asia. The Acrylonitrile operations, with their strategic position in the rapidly growing Asian market, have developed in concert with a strong and growing Acrylonitrile 22

demand, and in an overall program of timely restructuring of operations to effectively anticipate and meet the continuing rise in Acrylonitrile demand. The world acrylonitrile market grew from 1.9 million tones in 1994 to 2.2 million tones in 2001. Leading exporters are the USA, Denmark and France, while top importers include Germany, Taiwan, the UK, Belgium and Japan. The global acrylonitrile market is worth over US$620 million a year. In India: There are large demands of Acrylonitrile in India. But only IPCL produced and consumed itself. So, no export of Acrylonitrile and large amount of Acrylonitrile import in India. Importer of India: Following are some industries in India import acrylonitrile.(in 1983) Table 2.6: industries in India import acrylonitrile.(in 1983) COUNTRY

Austria

QUANTITY

CIF VALUE

Tons

Rs.

NAME OF IMPORTER

14.800

2,95,000

Asian Paints India Ltd.

14.800

2,98,100

Gharda Chemical Limited.

China

24.000

3,83,6000

Kantilal Manilal & Company

F.R.G.

25.000

5,02,800

BASF India Limited.

12.800

2,51,400

Colour Chem Limited.

Export Copr.

29.600

7,13,700

Indian Dyestuff Indust.

Netherland

4.564

89,900

Aditya Organics Pvt. Ltd.

10.106

2,12,200

Colour chem. Limited.

25.428

4,96,800

Standard Organics Limited.

25.428

4,90,800

STC of India Ltd.

S. Korea

10.150

1,92,600

Puneet Resins Pvt. Ltd.

Taiwan

12.800

2,31,600

Ganelex Trading & Fin. Ltd.

12.800

2,31,600

Shankarlal & Sons.

23

COUNTRY-WISE TOTAL IMPORTS Austria

29.600

5,93,100

China

24.000

3,83,600

F.R.G.

97.080

21,29,800

Netherland

65.526

8,48,600

Taiwan

25.600

4,63,200

Total

241.806

44,18,300

Now number of industries of India manufacturing acrylic fibers, Acrylic resins like ABS, SAN etc. and other intermediates import Acrylonitrile for their plant raw material In USA: The acrylonitrile business is heavily dependent on exports. From 1990 until the end of 1997, exports were more than 1 billion pounds per year, serving a rapidly growing acrylic fiber and styrenics industry in the Far East. In 1997, about 1.5 billion pounds of acrylonitrile were exported, roughly equivalent to domestic consumption. When that fell off at the end of 1997 and through 1998 and much of 1999, operating rates went down in the US by about 15 percent, and suddenly there was over-capacity based solely on a declining export market. For the past couple of years, exports have again grown to more than 1.5 billion pounds. But, because most of the anticipated new acrylonitrile capacity will be built in Asia, long term export market is at risk. Demand and Growth: Demand: 2000: 1,690 million pounds; 2001: 1,680 million pounds; 2005: 1,800 million pounds, projected. Demand equals production plus imports (2000: 17 million pounds; 2001: 5 million pounds) less exports (2000: 1,505 million pounds; 2001: 1,574 million pounds).

24

Table-2.7 Historical data: Year

Demand pounds)

1995

1,717

1996

1,712

1997

1,648

1998

1,649

1999

1,690

2000

1,680

25

(million

of

CHAPTER-3: PHYSICAL & CHEMICAL PROPERTIES

3.1 PHYSICAL PROPERTIES Acrylonitrile (C3H3N, mol wt. = 53.064) is an unsaturated molecule having a carbon ± carbon double bond conjugated with a nitrile group. It is a polar molecule because of the presence of the nitrogen heteroatom. There is a partial shift in the bonding electrons towards the more electronegative nitrogen atom, as represented by the following heterovalent resonance structures.

CH2 = CH-C = N:

CH2 = CH-C = N:

CH2-CH = C = N

Table-3.1 Physical Properties of Acrylonitrile: Property

Value

Appearance

Clear, colorless liquid

Odor

With faintly pungent odor o

Boiling point, C

77.3oC

Freezing point oC

83.5oC

Density, 20oCg/cm3

0.806

o

Volatility, 78 C,%

> 99 o

Vapor pressure, 20 C,K Pa

11.5

Vapor density (air = 1)

1.8

o

Solubility in water, 20 C, wt%

7.3

pH (5% aqueous solution)

6.0 ± 7.5

o

Critical Temperatures, C

246oC

Critical Pressure, Mpa

3.54

3

Critical Volume, g/cm

3.798

Refractive index, n 25/D

1.3888

Dielectric constant, 33.5 MHz

38

Ionization potential, eV

10.75

26

Molar refractivity (D line)

15.67

o

Surface tension, 25 C, mN/m (=dyn/cm)

26.6

Dipole moment, Cmc

1.171 x 10-29 ( For Liquid) 1.294 x 10-29 ( For Vapor)

Viscosity, 25oC,mPas (=cP)

0.34

Table-3.2 Thermodynamic Data: Property

Value o

Auto ignition temperature. C

481 o

Flammability limits in air, 25 C, vol%

Lower = 3.0 Upper = 17.0

o

Free energy of formation, Gg, 25 C KJ/mol Enthalpy of formation, 25oC KCal/mol

195 45.37 ( For gas) 36.2( For liquid )

o

Heat of combustion, liquid, 25 C, KJ/mol

1761.5

o

Heat of vaporization, 25 C, KJ/mol

32.65

Molar heat capacity, KJ (kg K)

2.09 ( Liquid) 1.204 (Gas at 50oC, 101.3 KPa )

Molar heat of fusion, KJ/mol

6.61

o

Entropy, S, gas at 25 C, 101.3kPab, KJ/ (mol K)

274

Table-3.3 Solubilities of Acrylonitrile in Water: Acrylonitrile in Water in Temperature, oC

Water, wt%

Acrylonitrile, wt%

-50

-

0.4

-30

-

1.0

0

7.1

2.1

10

7.2

2.6

20

7.3

3.1

27

30

7.5

3.9

40

7.9

4.8

50

8.4

6.3

60

9.1

7.7

70

9.9

9.2

80

11.1

10.9

Acrylonitrile is miscible in a wide range of organic solvents, including acetone, benzene, carbon tetrachloride, diethyl ether, ethyl acetate, ethylene, cyanohydrins, petroleum ether, toluene, some kerosenes, and methanon. Composition of some common azeotropes of Acrylonitriel is given in Table below. Table-3.4 Azeotrope of acrylonitrile: Boiling point, oC

Azeotrope

Acrylonitrile, Concentration wt%

Tetrechlorosilane

51.2

89

Water

71.0

88

Isopropyl alcohol

71.6

56

Benzene

73.3

47

Methanol

61.4

39

Carbon tetrachloride

66.2

21

Chloro trimethyl silane

57.0

7

Table-3.5. Acrylonitrile vapor Pressure over Aqueous solutions at 250C Acrylonitrile, wt%

Vapor pressure, kPa

1

1.3

2

2.9

3

5.3

4

6.9

5

8.1 28

6

10.0

7

10.9

3.2 CHEMICAL PROPERTIES: Acrylonitrile is a very reactive compound. The important reactions of Acrylonitrile are as below. Reactions of the double bond 3.2.1Polymerization: Acrylonitrile can undergo spontaneous, exothermic polymerization in the absence of hydroquinone inhibitor to give polyacrylonitrile (PAN). The homo and copolymerization of Acrylonitrile take place rapidly in the presence of radiation, anionic initiators or fire radical sources, such as peroxides or diazo compounds. H hv

|

nCH2 = CH-CH

[CH2-C]n initiator

| CN

The reaction involves charge transfer complexes between various monomers and can be produced in the vapor, liquid or solid, in solution and in dual-phase system. Only the latter two methods have industrial impact. 3.2.2 Hydrogenation: In the presence metal catalyst hydrogenation of Acrylonitrile gives propionitrile & propylamine. (C3H4N)

(C3H9N) Ni

C3H5N + H2

2H2 C3H5N

410oC 29

C3H9N

3.2.3 Hydrodimerization: Two molecules of Acrylonitrile react with hydrogen molecule to give adiponitriel over a metal catalyst. Metal 2CH2 = CHCN + H2

C6H8N2 Catalyst

3.2.4 Halogenations; In the presence of light Acrylonitrile react with halogens to produce dihalopropinitriles. CH2±CH- CN

CH2 = CHCN + Cl2

|

|

Cl

Cl

|

i) Production of acrylamide: For years the first step in the commercial production of acrylamide was the partial hydrolysis with sulfuric acid to acrylamide sulphate. Then it is converted to acrylamide (C3H5NO) by neutralization with a base. CH2 = CHCN + H2SO4 (+H2O)

CH3 CH2CNO.H2SO4 + NaOH

C3H5NO + Na2SO4 + H2O However, now acrylonitrile is converted directly to acrylamide using various copper based catalysts. CH2 = CH-CN + H2O ±Cu

C3H5NO

ii) Production of methylacrylate: Industrially important acrylic esters can be formed by reaction of acrylamide sulphate with organic alcohols. Methyl acrylate C4H6O2 has been produced commercially by the alcoholysis of acrylamide sulphate with methanol. 30

CHAPTER-4: LITERATURE SURVEY

4.1 LITERATURE SURVEY The Literature Survey is the most import part of the Project Work. The Literature survey has been done to obtain information concerning Acrylonitrile and its production from the number of sources. The literature survey yielded a lot of information on Acrylonitrile In literature, various available and absolute processes are known and I choose Sohio as the best process among them. I find the raw materials used, also power and other utilities required for processes, also by product obtained, also about safety and environmental consideration. So, one can economically deiced the proper manufacturing processes which can give maximum product output with lower operating cost. As per periodicals, lots of information is available. The periodicals give us the abstract about articles and its reference. The books related to chemical engineering and technology, handbooks, encyclopedias, Symposiums, Journals and Plant training manuals are very useful available sources of most of project work. The CD-520V VSHFLDOO\ &'V RI ³3HUU\¶V +DQGERRN´ DQG ³%DVLF 3ULQFLSDO DQG &DOFXODWLRQLQFKHPLFDOHQJLQHHULQJE\+LPPHOEODX´IURP3HUU\µV&'ORWVRIILJXUHV and required theory as well as date available. The Himmelbau CD Rom is very user friendly in calculation part of energy valance and designing. The other source of Literature Survey is the internet websites. From websites it is very helpful in find out available information related to Acrylonitrile world wide. It is particularly very helps in find out latest information about price, capacity data related to Acrylonitrile and also various manufacture of Acrylonitrile.

31

4.2 ACRYLONITRILE AND SOHIO PROCESS: 4.2.1 Early History: Acrylonitrile, first synthesized in 1893 by Charles Moureu, did not become important until the 1930s, when industry began using it in new applications such as acrylic fibers for textiles and synthetic rubber. Although by the late 1940s the utility of acrylonitrile was unquestioned, existing manufacturing methods were expensive, multistep processes. They seemed reserved for the world's largest and wealthiest principal manufacturers: American Cyanamid, Union Carbide, DuPont, and Monsanto. At such high production costs, acrylonitrile could well have remained little more than an interesting, low-volume specialty chemical with limited applications. In the late 1950s, however, Sohio's research into selective catalytic oxidation led to a breakthrough in acrylonitrile manufacture. The people who invented, developed, and commercialized the process showed as much skill in marketing as in chemistry. The result was such a dramatic lowering of process costs that all other methods of producing acrylonitrile, predominantly through acetylene, soon became obsolete.

At this site in 1957, Sohio researchers developed the "Sohio Acrylonitrile Process," an innovative single-step method of production that made acrylonitrile available as a key raw material for chemical manufacturing worldwide. Sohio as groundbreaking experimentation and bold engineering brought plentiful, inexpensive, high-purity acrylonitrile to the market, a principal factor in the evolution and dramatic growth of the acrylic plastics and fibers industries. Today, nearly all acrylonitrile is produced by the Sohio process, and catalysts developed at the Warrensville Laboratory are used in acrylonitrile plants around the world. Sohio became part of The British Petroleum Company p.l.c. in 1987.

32

4.2.2 Acrylonitrile Chances are that acrylonitrile touches everyone in some way every day. Acrylonitrile is the key ingredient in the acrylic fiber used to make clothing and carpeting; in acrylonitrile-butadiene-styrene (ABS), a durable material used in automobile components, telephone and computer casings, and sports equipment; and in nitrile rubber, which is used in the manufacture of hoses for pumping fuel. Acrylonitrile is used to produce plastics that are impermeable to gases and are ideal for shatterproof bottles that hold chemicals and cosmetics clear "blister packs" that keep meats fresh and medical supplies sterile, and packaging for many other products. It is also a component in plastic resins, paints, adhesives, and coatings. The acrylonitrile in those products was made by a process discovered and developed in the 1950s by scientists and engineers at The Standard Oil Company, or Sohio, which became part of British Petroleum (BP) in 1987. The process is a single-step direct method for manufacturing acrylonitrile from propylene, ammonia, and air over a fluidized bed catalyst. The discovery and commercialization of this process were the result of the talent, imagination, teamwork, and risk-taking by Sohio's employees. Sohio's discovery led to the production of plentiful and inexpensive acrylonitrile of high purity as a raw material and to dramatic growth in the thermoplastics, synthetic fiber, and food packaging industries. Today more than 95% of the world's acrylonitrile is produced by BP or made under its license. 4.3 SOHIO PROCESS-RESEARCH AND DEVELOPMENT: Sohio process was extensively tested in operation of a pilot plant unit for several months at the Sohio Research centre in Cleveland. The product from this unit was fiber grade and major U.S. consumer specification Substantial quantities were polymerized, spun into fiber dyed, with complete acceptance. Some of the special aspects of the Research and development program be of interest. The initial research work was conducted in small plant of the type shown in Figure 1 33

with steel tubular reactors were employed. Vapor chromatography analytical tool. The reaction studies were supported by special product recovery and operation studies. Multiplate glass Oldrshaw distillation columns with an internal design shown in Figure2 were used to obtain design date. This column resembles a miniature glass sieve tray complete with down comers. One-and two-inch diameter units of appropriate plat age were used. Correlation of work done in this equipment with actual plant operation has been excellent in spite of the tremendous scale-up factors. The second step in the reactor scale-up was conducted in equipment of the type FDOOHG³$GYDQFHPHQW´XQLWV7KH\KDGDQLQWHUQDOGLDPHWHURIDERXWWKUHHLQFKHVDQG employed one to two liters of catalyst charge. Much of the basic plant reactor design and operating in formation came from units of this size with little or no modification ensuing from the subsequent larger scale pilot plant operation. 4.3.1 Pilot plant evaluation The pilot unit operation was not aimed at securing detailed plant design data but predominantly to give a firm evaluation of catalyst life and to supply market development samples. The pilot unit chosen was an 18 in, I.D. reactor with a catalyst charge of several hundred pounds. The recovery equipment was of the Oldershaw type made predominantly of glass units in the four and six-inch diameter size range. It may be of special interest to note that certain phases of the research work, the process advancement work, the pilot operation, and the detailed plant design were all conducted simultaneously. This type of simultaneous operation can greatly compress the time required to get an interesting process to plant stage. It creates a certain amount of discomfort and occasional back-tracking, but over-all progress can be speedily made if all groups involved are in close proximity and daily contact.It also brings t bear at an early stage the tremendous know-how available from the contract firms and can save substantial amounts of money in eliminating pilot scale work not needed for actual plant design.

34

4.3.2 Commercial aspects worldwide The detailed plant design shown it will have a low electrical load, a relatively small fresh water requirement, will be self-sufficient in steam, and will produce no unusual water effluent. Detailed economic studies indicate that for essentially all foreseeable sets of economic conditions and plant sizes, the Sohio process compares favorably with conventional routes in respect to investment, raw materials, operating costs, and product quality. It appears that small plants can be fully competitive with the previous larger facilities which has t he integrated with HCN, C 2H2, or ethylene oxide production. Plants do not have to be at the raw material site, since both propylene and anhydrous ammonia are readily transported. Plant construction materials are conventional and all operations are near atmospheric pressure except for steam generation. Sohio has decided to commercialize this process abroad and an active exploitation program is underway on a world-wide basis. It appears that many for3eign countries are eager to enter or expand acrylic fiber manufacture. The new raw material picture supplied by this process enables operation at many sites where production from C 2H2 and HCN would be impossible to uneconomic. 4.4 REACTION KINETICS: Laboratory has found that the ammoxidation reaction over bismuth molybdate containing catalysts has first-order dependence with respect t o propylene and a zeroorder dependence on both oxygen and ammonias when they are supplied in at least stoichiometric amounts. Kinetic measurements were made up to high digress of conversion in both fixed and fluidized catalyst beds. Differential reactors, designed with draw-off ports so that a small portion of the reaction products could be withdrawn for analysis after fixed reaction times, were employed. The fluidized bed reactor contained sieve trays, which results in a more nearly plug flow of the gas through the reactor allowing more accurate control of residence time. Composition of the bismuth-phosphomolybdate catalysts used in both reactors was 24.1% Bi, 14.8% Mo, 0.4% P, 23.4% Si, and the

35

balance oxygen. A 3/16 inch x 3/16 inch cylindrical pellet was used in the fixed bed, and a micro spherodal form was used in the fluidized bed. A PFR is used for producing acrylonitrile from propylene, ammonia and oxygen. The reaction rates are found to be independent of NH3 or O2 concentrations and can be represented as C3H6 + NH3 ------> C2H3CN + 3H2 ..«««««««   C3H6 + O2 -------> C2H3CHO + H2O .«««««««   C2H3CHO + NH3 -----> C2H3CN + 2H22«««««   At 470 deg C, k1 = 0.195 s-1, k2 = 0.005 s-1, and k3 = 0.4 s-1. The feed at the rate of 4200 kg/hr to the reactor contains 6.6% propylene, 86.1% air and 7.3% NH3. Design the PFR for a desired conversion of 85%. Activation energies of the ammoxidation reaction were determined from Arrhenius plots, and the values obtained for propylene were 19 K cal per mole in the fixed bed and 17 K cal per mole in the fluid bed. This is in agreement with values of 19 to 21 K cal mole reported by Kolchin and coworkers (1964). Kinetic measurement under acrylonitrile synthesis conditions follow a first-order dependence of reaction rate on propylene concentration and essentially zero-order on propylene concentration and essentially zero-order dependence on both oxygen and ammonia concentration when these reactants are provide in a t least slight excess. A common rate limiting step involving abstracting of hydrogen from the methyl group of propylene appears to be operative in ammoxidation reaction. 4.5 CATALYST DEVELOPMENT FOR SOHIO PROCESS: The

catalyst

originally

employed

in

the

Sohio

Process

was

bismuth-

phophomolybdate combination. Since that time there has been a continuous search for alternatives and for superior performance, resulting in patents by more than 30 companies. Sohio introduce a catalyst 21 basically combination of antimony-uranium in 1967, then possible to considerably reduce the amount of acetonitrile which was one of the by products. Further advances were achieved on using modified bismuth molybdate catalyst containing iron compounds (among others) to increase the selectivity. This 36

modification with iron is based on research work conducted by Knapsack. This catalyst was introduced by Sohio as catalyst 41 basically combination of ferro bismuth-phophomolybdate in 1972. In 1978, Sohio introduced catalyst 49 with aimed at improved efficiency and reduction in by products. 4.6 CATALYST MECHANISM: The Sohio catalyst, which requires a higher temperature of 4200C, comprises iron, antimony, molybdenum, vanadium, tellurium, and copper, supported on silica. It gives an overall acrylonitrile yield of 80% and a hydrogen cyanide yield of 3% with no acrylonitrile. The ammoxidation reaction is highly exothermic and is carried out in a fluidized bed to ensure effective heat exchange and temperature control. The mechanism for the formation of acrylonitrile from ammoxidation of propylene is shown in figure. The mechanism is illustrated for the original Sohio catalyst, and oxidized bismuth molybdenum species, which reacts with ammonia to give the imminium compound (VIII). This bond with an allyl radical resulting from the abstraction of hydrogen from propylene (II) to give (IX). As indicated in s(X) a double hydride shift occurs to liberate 1 mol of ammonia and to give the species (XI). This is oxidized to give(XIII), which forms (XIII) by a hydride shift Compound (XIII) undergoes the transformation shown in (XIV) to give the desired product acrylonitrile (XV), and the catalyst species (XVI), which with oxygen regenerates the initial catalyst species(I) 4.7 SYNTHESIS OF POLY (ACRYLONITRILE): 4.7.1 Polymerization processes include: Bulk Poly(acrylonitrile) is not soluble in its monomer. The reaction is autocatalytic, and as the viscosity increases, it becomes increasingly difficult to remove heat. The reaction may run out of control if done by a batch process. 1. emulsion 2. suspension 3. slurry 4. solution

37

Dimethylformamide is the solvent to use for a solution process. Acrylamide polymerizes exothermically in the presence of free radical or anionic initiators. Oxygen is a strong inhibitor, but it forms peroxides, explosion may take place. Once all the oxygen has reacted, the polymerization begins; the peroxides begin to thermally degrade. The solvent must form hydrogen bonds with strength comparable to that of the polymer chains, but also separate the polymer molecules with a nonpolar segment. Dimethylformamide

works,

but

form

amide,

methylformamide,

and

Dimethylformamide do not. Glass transition temperature- 105 deg C 4.8 ECONOMICS ± ACRYLONITRILE: The strongest factors in future Acrylonitrile pricing will be the improvement of profess technology and the future price of propylene feedstock. For that let us first look at the approximate sales price breakdown for Acrylonitrile, then at the propylene market. From the various information of Capital and operating casts calculations we can reach several conclusions about Acrylonitrile pricing. 1. Propylene constitutes 35 to 45% of the selling price of Acrylonitrile. Reaction yield and price of propylene will therefore be very important 2. As usual with commodity [necessary things] petrochemical both scale of plant and average capacity utilization are important factor in required selling price. With these economics in mind, we should also observe how sensitive this cost structure is to changes in the environment or errors in our assum0tions. For example, As reported by U.S. Tariff Commission if the plant is designed with a 440 million lb/year capacity (assuming technical feasibility), costs could be 1.0 cents/lb lower when operating at 90% of capacity. On the other hand, operating at only 75% of capacity in the above plant would increase unit costs by 0.7 cents/lb. Choosing just WKH³ULJKW´VL]HRISODQWWRVHUYHDYDLODEOHPDUNHWVZLOOWKXVEHTXLWLPSRUWDQW Another environmental factor is the forecast increase in costs of both energy and hydrocarbon feedstock. Price for Gulf Coast natural gas will cause a direct increase in required Acrylonitrile price. The indirect increase in ammonia prices would add 38

another to Acrylonitrile prices. Propylene is a more complex question, however, and calls for a detailed analysis because of its nature as a by-product of both refining and olefins production. Several recent articles have been published on propylene and the consensus seems to be that propylene prices will either decline or at least not increase as rapidly as other basic petrochemicals. While large quantities of propylene are used in making alkylate fore leaded gasoline, propylene alkylate is inferior to butylenes alkylate in a nonleaded gasoline pool. After the available isobutane and alkylation capacity are allocated to butylenes, not enough will be available to expand usage of propylene in refineries. At the same time, steam crackers are being built t handle heavier feed stocks (naphtha, gas oils) instead of the ethane and propane fed in the past. Since these feed stocks produce 0.4 to 0.65 more kgs of propylene for each kg of ethylene than ethane feedstock. Olefins producers will have a disproportionate increase in their available propylene. While propylene markets are expanding, they have generally not been forecast to grow as rapidly as ethylene markets. However, a relatively lower propylene price will act to bring an adjustment of the relative growth rates by encouraging the substitution of propylene derivatives (poly propylene, Acrylonitrile, propylene oxide) for competing ethylene derivatives (polyethylene, vinyl chloride, ethylene oxide). This will work to hold down Acrylonitrile prices, especially when combined with application of 4h e new Sohio catalyst t existing plants and several large new plants. In doing he price forecast, a statistical study by Professor Robert Stobaugh and the author has pointed out 4 factors which underly past declines in petrochemical prices [4]. The 2 strongest factors in prices declines of 82 petrochemicals over a 17-year period were: (1) the increasing scale economies of ever-large production facilities; and (2) the efficiencies resulting from accumulating production experience (e.g., the recently announced catalyst). These factors will continue to work for lower Acrylonitrile prices.

39

Slightly less important as factors in the past are trends toward (3) more producers and (4) more standardized products. Both of this acted t cut profit margins toward a ³FRPPRGLW\´ OHYHO DQG VKRXOG FRQWLQXH WR GR VR LQ WKH IXWXUH :KLOH $FU\ORQLWULOH has a standardized quality, the present six U.S. producers could be joined by one or two others in the next decade. The importance of large volume and propylene pricing suggests that other oil companies may join Sohio in Acrylonitrile production, with some resultant reduction Acrylonitrile price. This would be quit consistent with the product life cycle as it applies to petrochemicals. As they mature, many other petrochemicals have attracted oil companies and exhibited declining real manufacturing costs. While other petrochemicals will reverse this trend in the next decade, Acrylonitrile has an excellent position continue the trend of declining real price. On balance, then (1) technology improvement, (2) low propylene prices, (3) larger plants, and (4) competitive threats of new producers should overcome increases in other production costs to reduce real Acrylonitrile prices or allow for relatively modest price increase. This price advantage over competing monomers will help to bring about the continued expansion of Acrylonitrile derivatives through 1983.

40

CHAPTER-05: PROCESS SELECTION

5.1 BASIC MANUFACTURING PROCESSES: Although a variety of chemical routes to acrylonitrile have been proven, and various processes developed, present practice concentrates exclusively on the ammoxidation of propylene. In the great majority of cases the Sohio fluid-bed process is used. Considering the chemistry first, the more important routes, listed by chronological development, have been the following: 5.1.1 Ammoxidation of Propylene:There are a number of Ammoxidation of Propylene processes for manufacturing acrylonitrile among them; the Sohio process has attained the greatest industrial importance of all the Ammoxidation processes. Ammoxidation represents the catalytic oxidative reaction of activated methyl groups with NH3 leading to the formation of a nitrile group and is react with propylene to obtain acrylonitrile. H2C = CHCH3 + NH3 + 1.5 O2

H2C = CHCN + 3H2O [Cat.]

(a) Sohio Process: Process Principle: Heterogeneously catalyzed single-step gas-phase oxidation of propylene in presence of NH3 and air using bismuth phosphomolybate on silica catalysts in fluidized bed reactor. Technological Characteristics: Heat from exothermic main, side and secondary reactions evolved, via fluidized bed and heat exchanger utilize in steam generation. H2C = CHCH3 + NH3 + 1.5 O2

H2C = CHCN + 3H2O

[Catalyst = bismuth phosphomolybate] Process Description: In the industrial Sohio process, approximately Stochiometrical amounts of Propylene is reacted with slight excess of NH3 and excess of air in the fluidized bed reactor in 41

42

Figure-5.1 Acrylonitrile by Sohio Process

presence of catalyst at temperature of 400-450 OC and gauge pressure 30-200 KPa (0.3-2 bar)with residence times of a few second about 20 seconds. The propylene is converted to acrylonitrile with a yield of 80% obtainable. The principles by products are acrylonitrile and Hydrogen Cyanide. One Kg of propylene yields 0.8 ± 0.9 kg acrylonitrile, 0.02 ± 0.11 kg acrylonitrile, and .1 ± 0.15 kg hydrogen Cyanide. The gases from highly exothermic reaction are cooled by means of internal water coils. The Reactor effluent is cooled. Unreacted ammonia is removed by water acidified with sulphuric acid as aqueous ammonia Sulphate, which can be recovered by crystallization. Scrubbing in on absorber column separates off-gases overhead. Consisting primarily of nitrogen, is vented. The reaction products remain in aqueous phase. Acrylonitrile is removed by extractive distillation and is recovered. The crude acrylonitrile and hydrogen Cyanide are distilled into the recovery column where it is steam stripped. Hydrogen Cyanide is removed by distillation as the light impurities which can recover as buy product. The acrylonitrile is purified to get pure acrylonitrile. (b) BP (Distillers) ± Ugine route: The ammoxidation technology initially developing in the 1905s as a result of collaboration between PCUK (Produits Chimiques Ugine Kuhlmann), BP (Distillers), and Border Chemicals. In 1965 two plants based on the technology went into operation. During recent years, Distillers and PCUK have continued developing and marketing an acrylonitrile process that is the outgrowth of the technology begun in the 1950s. Plants using the PUCK Technology are now located in Great Britain, France, Mexico, and Korea. The technology is most notably distinguished from that of Sohio by the use of fixed bed reactors instead of fluidized bed reactors. Process Principle: Two step propene reaction with interim isolation of acrolein. Process Description: Using the BP (Distillers) - Ugine process, propene is initially oxidized on a Se/CuO catalyst to Acrolein which it then converted into acrylonitrile in a second stage

43

employing NH3 and air with a MoO3 fixed-bed catalyst. This two-step conversion leads to a higher acrylonitrile selectivity of approx. 90% (based on H2C = CHCHO). (c) UOP - Montedison route: Montedison became interested in acrylonitrile manufacture in the early 1950s. in 1956 the company commissioned a plant near Venice, Italy that produced acrylonitriel from acetylene and hydrocyanic acid. By 1967 the company had begun operating a small semi-industrial fluidized ammoxidation reaction system (i.e., one operating with propylene, air, and ammonia in a fluidized bed reactor) that had been developed in their own laboratories. This was followed by construction and operation of Montedison-type acrylonitrile plants in Priolo, Sicily (1968), and in Puertollano, Spain (1973). In 1975 UOP and Montedison entered into an agreement under which UOP acquired exclusive licensing rights. As a result of the agreement, process improvements have been made. (d) Nitto Technology: For several years the Nitto Chemical Industry Company of Japan has been attempting to develop improved catalysts for the ammoxidation of propylene to acrylonitrile. The principal reactions for the ammoxidation step are same as Sohio process Basic Difference

is

the

different

catalyst.

In

1974

the

company

announced

FRPPHUFLDOL]DWLRQ RI &DWDO\VW 16$ DV ³&DWDO\VW ´ containing Fe, Sb, and other components. Probably, acrolein, acetone, acetaldehyde, proponaldehyde, and high boiling cyanohydrins are formed in small amounts. (e) Based on Propane or Propylene geed Stock: Lummus has also developed an acrylonitrile manufacturing process based on propane or propylene; NH3 and O2 in a salt melt of e.g. KCl ± CuCl ± CuCl2. Commercial processes are not in operation so far. 5.1.2 From Ethylene Cyanohydrin Route: The first industrial production of acrylonitrile based on ethylene oxide, was developed by IG Farbenin and Leverkusen in Germany in early 1940s and operated by Union Carbide in the United States from 1952 onwards and by American 44

45

Figure-5.2 Acrylonitrile by Ethylene Cyanohydrin route

Cyanamid from 1970. During the interim period around mid-1960s both plants have been shut down. Process Principle of Ethylene Oxide Route: Two-step homogeneously catalyzed reaction to intermediate Cyanohydrin with subsequent homogeneously or heterogeneously Catalyzed dehydration. C2H4O + HCN

CH2(OH)CH2CN [Al2O3 Cat.]

CH2(OH)CH2CN

H2C = CHCN + H2O [Al2O3 Cat.]

Material Required: Basis

: 1 ton Acrylonitrile (99%)

Ethylene Cyanohydrin : 1400 kg Catalyst

: Small quantity

Process: The process involved the base catalyzed addition of HCN to ethylene oxide forming ethylene cyanohydrin. Acrylonitrile can be manufactured by dehydrated ethylene Cyanohydrin. Pass continuously refined Cyanohydrin either over a dehydration catalyst activated reduced pressure between 250 to 350 OC in the vapor phase or in the liquid phase at 200OC in the presence of alkali m3etal or alkaline earth metal Salts of Organic acid, Primarily

Magnesium Carbonate. Condense the reaction

products coming out from Reactor and pass into a decanter where water layer and organic layer i.e. crude acrylonitrile layer separate out. The water layer discard and crude acrylonitrile layer charge into a fractionating column and return the lowboiling heads to ethylene cyanohydrin still. The bottom consist high boiling impurities and are generally discarded. Recover 99 % purity dry Acrylonitrile Substantially from middle of column. 5.1.3 Acetylene- Hydrogen Cyonide: It is the another industrial pathway developed by Bayer and commercially operated by American DuPont, Goodrich, Knapsack, and Monsanto involved the CuCl-NH4Cl catalyzed addition of HCN to acetylene at 70-80 OC: At the end of the sixties, the 46

47

Figure-5.3 Acrylonitrile by Acetylene-HCN route

Monsanto and Cyanamid plants were shut down. Consequently at the beginning of the seventies less than 1% of the total acrylonitrile production was manufactured according to this route. Process Principle of Acetylene Route: Single-step, homogeneously Catalyzed hydrocyanation in the liquid phase Reaction HC=CH + HCN

H2C = CHCN [Cu2Cl2 Cat.]

80 % yield Material Requirements: Basic

: 1ton acrylonitrile (99%)

Acetylene

: 545 kg

Hydrogen Cyanide

: 545 kg

Catalyst loss (contained copper) : Small Process: Acrylonitrile is produced by the reaction of acetylene and hydrogen cyanide in the presence of a catalyst under either liquid or vapor-phase conditions. Acetylene and hydrogen cyanide in a molar ration of 10 to 1 are feed into a rubberlined cylindrical reactor that is kept about two thirds full of catalyst solution. The aqueous solution contains 26 per cent cuprous chloride (based on the weight of dissolved copper). The catalyst may be used to produce approximately 20 kg of acrylonitrile per kg of dissolved copper before regeneration. This may be conveniently accomplished by precipitating the copper with zinc and reconverting to cuprous chloride. The aqueous catalyst solution is maintained at a temperature of 70OC, and the reactor is operated at essentially atmospheric pressure. The reaction gases from the top of the reactor contain acrylonitrile, unreacted acetylene, 1 to 3 per cent hydrogen cyanide, and small amounts of numerous byproducts such as acetaldehyde, vinyl acetylene, divinyl acetylene, vinyl chloride, cyanbutadiene, lactonitrile, and chloroprene. The gases are washed counter currently

48

with water in a scrubber, which removes the acrylonitrile, hydrocyanic acid, and some of the by-products. The washed gases are recycled to the reactor. The water solution, containing about 1.5 per cent acrylonitrile, is steam-distilled in a column to give 80 per cent acrylonitrile. The crude product is fractionated in a series of columns to yield 99 percent pure acrylonitrile. The yield based on acetylene is about 80 percent and is somewhat higher (90 to 95 per cent) based on hydrocyanic acid. The greatest losses in yield arise from formation of vinyl acetylenes and their derivatives. Various patents cover removal of vinyl acetylenes from the liquid phase before distilling acrylonitrile and from the gaseous phase prior to recycling acetylene. The vapor-phase process involves passing a mixture of equal volumes of acetylene and hydrogen cyanide over a fixed metallic cyanide catalyst (suspended on an inert carrier) at temperatures of 400 to 500 OC. The gaseous reactants may be diluted with steam or inert gases to improve the yield, but it is still reported to be rather low. The addition of an acidic substance, such as phosphoric acid, to the crude reaction product entering the column is said to reduce secondary reactions and increase the yield of acrylonitrile. 5.1.4 Acetaldehyde-hydrogen Cyanide Reaction: Another process by Knapsack-Griesheim remained industrially insignificant. Acetaldehyde react with HCN froming the nitrile of lactic acid i.e. lactonitrile which was then dehydrated to acrylonitrile at 600-700OC in presence of H3PO4. Process Principle of Acetaldehyde Route: Two-step reaction initially to acetaldehyde cyanohydrin i.e. lactic acid nitrile with subsequent catalytic dehydration. Reaction: CH3CHO + HCN

CH3CHCN | OH

CH3CHCN |

H2C = CHCN [Cat.]

OH 49

The first stage of this reaction is still operated in Japan today, it serves however to manufacture lactic acid by hydrolysis of lactonitrile in the presence of H2SO4. CH3CHCN

CH3CHCOOH

|

|

OH

OH

Lactic acid nitrile presently use only as intermediate in lactic acid manufacture. Lactic acid is isolated as its methyl ester and purified. Musahino operates a 5,000 ton/annum plant. 5.1.5 Nitrosation of Propylene: It is the process no longer operated today, provides the transition at the modern manufacturing routes to acrylonitrile as propane is employed ad feedstock. DuPont developed propane nitrosation process, then operated it for a period in a pilot plant in the USA. By means of this process, propane was catalytically reacted with NO using Ag2O/ SiO2 or alkali metal oxide with thallium or lead compounds: 4H2C = CHCH3 + 6NO

4H2C = CHCN + 6H2O + N2

[catalyst] A silver oxide on silica catalyst in employed, the reaction temperature being in the region of 5000C. At one time a Du Pont plant in Beaumont, Texas, employed a process based on this reaction 5.1.6 Future Processes: Just like propylene, propane should also be a suitable feed stock for the Ammoxidation. Monsanto Power Gas, process based on propane or propylene, and ICI have developed and are doing research work on production of acrylonitrile from propane as a main raw material along with NH3 & O2, using oxides of the and tungsten as catalyst at 485-520 OC temperature. It has been claimed on pilot plant scale that by the use of above catalyst, the formation of highly poisonous Hydrogen Cyanide as by product could be avoided to large extent. Thus, this process appears to be technological alterative of future for the production of acrylonitrile. The economic advantages of the process are claimed to be the price advantage of propane over propylene not much differ, increased production of Valuable acetonitrile and HCN 50

by products instead of others and lower effluent cost. It is hoped to introduce the process at the beginning of the Mitsubishi Chemicals and BOC have also developed a propane-based ammoxidation process which has higher selectivity than typical propylene-based systems. 5.1.7 Dual Process: A combination of two process i) propylene ammoxidation and (ii) addition of HCN acetylene can be used as an economical industrial process. Ammoxidation of propylene gives HCN as a by product alongwith ACN the main product by following reaction. C3H6 + NH3 + 1.5O2

CH2CHCN + 3H2O (Main reaction)

1/3 C3H6 +NH3 + O2

HCN + 2H2O (Side reaction)

HCN thus produced is about 8% of total ACN produced, which can be reacted with acetylene to convert it into ACN. C2H2 + HCN

CH2CHCN

Thus, in this processes, HCN is totally used up, hence it is and intrinsically safe process. 5.2 WHY SOHIO PROCESS IS THE BEST? Propylene ammoxidation using Sohio Process has following advantages over other processes for production of acrylonitrile. 5.2.1Process: Sohio process gives highest conversion of propylene (about 98%) with high selectivity for ACN. It is a once through process, not recycle of reactants is required The reaction flow diagram is quit simple. It consist of catalytic, vapor phase, one step conversion operating at a moderate temperature (below 500 0C), ordinary pressures (below 3 atmospheres), and residence time of a few seconds. 5.2.2 Raw Material In Sohio process refinery propylene and conversional fertilizer grade anhydrous ammonia along with air are the only raw materials. Propylene concentration is not 51

critical; with 50 to 90% propylene acceptable is a reactor feed. All the materials cost less and are more abundant on world wide basis than the previously used raw materials: ethylene oxide, acetylene, and acetaldehyde, hydrogen cyanide. The older processes for manufacturing acrylonitrile employ the relatively expensive Raw Material building 5.2.3 Handling of Hydrogen Cyanide:Acrylonitrile is produced by Ethylene Oxide or acetylene reaction with Hydrogen Cyanide [HCN]. But HCN is the highly poisonous which is used as raw material and far large amount of the lethal chemical has to be stored and handled. While in Sohio process HCN is obtained compare to in small quantity as a by-product. Thus, in comparison to acetylene or ethylene oxide based process, propylene based process appears to be for superior technological alternative as the highly poisonous HCN has to be handled is a far less quantity. Hence Sohio process is safer than other processes using HCN as a raw material 5.2.4 Catalyst Development:The Sohio process has remained economically advantaged over other process technologies since the first commercial plant in1960 because of the higher acrylonitrile yields resulting from the introduction of improved commercial catalysts. Reported per-pass conversions of propylene to acrylonitrile have increased from about 65% to over 80% with developed catalyst. 5.2.5 By products:The major by product is Acetonitrile, which sold as two preclude volumes age. Acetonitrile power full resins and has some other unique associated with the extremely high polarity of the cyano group. Other by product is HCN widely used commercially recoverable by product. 5.2.6 Fluidized bed reactor:Because of Fluidized bed reactor, get advantage of it over fixed bed reactor. Although loss of catalysts is more in fluidized bed reactor than in fixed bed reactor, the higher yield in fluidizing bed reactor overshadows loss due to catalyst carryover. Moreover,

52

the loss of catalyst can be minimized by providing properly designed internal cyclones. 5.2.7Other comments:An advantage of Cyanohydrins process is that it produces lesser amount of impurities; however it is not economically competitive with Sohio process. The drawbacks of acetylene - HCN process were expensive raw materials, formation of some undesirable impurities like divinyl acetylene and methyl vinyl ketone which are difficult to remove and the frequent regeneration required for catalyst. Propane based processes are more economical than Sohio process due to difference in their prices. However this price difference is not likely to be great enough in the near future to dictate change. 6RILQDOO\FRQFOXGHWKDW««««««« The propylene-based process developed by Sohio was able to displace all other commercial production technologies because of its advantages of highest conversion rate of propylene (about 98%) with high selectivity for ACN[80%]., lower raw material costs, no recycle of unreacted raw materials i.e once through process and these will result in overall product cost is become lower. Any industry will become more profitable as it will manufacture product with high conversion and at low cost. So, the conclusion can be drawn that, acrylonitrile produced by Sohio process is more feasible, practicable and economical and this can be also proved as in United States all capacity and about 90% of the world capacity far acrylonitrile production is based on the Sohio process. 5.3 SELECTION OF CAPACITY: IPCL, Baroda is the sole producer of acrylonitrile in India with plant capacity of around 30000 ton per annum. All industries in India required Acrylonitrile is imported. The current Indian demand is very large and would further increased in future depend upon the market of its uses as resins, fibers, rubbers and as other intermediates. So, company has to try to increase acrylonitrile production to overcome current demand and future regulatory demand. Hence, a capacity of 70000 MTPA is selected for Acrylonitrile plant based on Sohio Process. 53

CHAPTER-06: THERMODYNAMICS & KINETICS

6.1 Process Description: The reactor section can be divided into three parts. 1. Preparation of feed 2. Mixing and reactions. 3. Heat removal from reactor and gases. Ammonia, propylene and air are feed material. Liquid ammonia is fed to ammonia vaporizer in shell side stream via fitter. Ammonia is vaporized by absorbing heat from the side stream water of the absorber. Vaporized ammonia is then passed through an entrainment separator to remove and return any liquid ammonia entertainment. Vapor ammonia is now passed through super heater where vapor ammonia is heated to 65 oC using low pressure stream. Superheated ammonia at 65 OC is fed to the reactor at pressure 2.3 Kg/cm2 g. Propylene is supplied to plant in liquefied form in pipeline from petrochemicals plant. Liquid propylene is directly sent to vaporizer by passing it through propylene fitter. This propylene is vaporized in vaporizer as in case of ammonia. Then, vaporized propylene is now passed through entrainment separator and super heater as per ammonia. The temperature of superheated propylene vapor is 65OC and it is fed at 2.5 Kg/cm2G pressure to reactor. Air is sucked from open atmosphere by using an air compressor. The air compressor is run by a steam turbine which is fed with high pressure steam obtained by using heat of reaction in reactor. This saves electricity and it is important from economic point of vies. The air compressor provides air at 2.5 Kg/cm2 g pressure. The Acrylonitrile is produced by SOHIO Process using ammoxidation of propylene in fluidized bed catalytic reactor, can conveniently divided into three section: 1. Reactor section 2. Recovery section 3. Purification section 54

6.1.1 Reactor Section: The fluidized bed catalytic reactor is the heart of process. Liquid ammonia and liquid propylene are vaporized and propylene and ammonia vapors are superheated by passing through super heater. Propylene and ammonia enter the reactor through feed sparger with mixing. The process air compression provides reaction air at 2.5 Kg/cm2 g., before entering the reactor, the air from the air compressor is passed through start up heater. Air is admitted to the reactor bottom where it passed into fluidized bed through a air grid. The air grid is below the propylene ammonia feed sparger. Feed to Reactor:Ammonia at 2.3 Kg/cm2 g and 65 0C Propylene at 2.5 Kg/cm2 g and 65 0C Air at 2.2 Kg/cm2g and 170 0C The expected feed mole ratios are approximately Propylene - 1.0 Ammonia - 1.23 Air

- 9.1 to 9.3

Beside the possibility of catalytic reduction the ammonia to propylene ratio is too low, there will be an excess consumption of sulphuric acid to remove excess ammonia. The air to propylene ratio mentioned above is design number and the actual ratio may vary with operation. Propylene, ammonia and air flowing up through the reactors fluidizing the bed of catalyst. The catalyst B CM9 MC & C 491 MC is used which is finely divided solid in the 10 to 100 micron range. The reactor is normally operated at a pressure 0.75 Kg/cm2 g at top and a temperature between 430 to 450OC. The reactor gives an 80 mole percentage conversion of propylene to Acrylonitrile, using catalyst C 491 MC. Because of the reaction which take place forming acrylonitrile and other products are exothermic Therefore, cooling is necessary to maintain temperature in reactor. The reactor contains multiple sets of vertical U-tube coils through which treated condensed water pass. Heat from reaction is transferred to the circulating water in 55

coils producing steam 41.5 Kg/cm2 g. The saturated steam passes through coil to produce superheating the steam. Various number of these steam coils can be placed in service or taken out of service, in order to affect temperature control in reactor. Temperature control can also be accomplished by adjusting the feed rates. The catalyst bed level is maintained in reactor. If the bed level is too low, the cooling coils will be uncovered and not be enough cooling surface available to properly6 control the reactor temperature. If the bed level is too high, catalyst losses may be excessive. The Reactor also contains cyclone separators through which the effluent gases must pass before they leave the reactor. These cyclone separators remove most the catalyst which has been carried along with the gaseous stream. The catalyst drops into a dip leg at the bottom of each separator and is returned to the catalyst bed. Each dip leg is equipped with trickle valve. The trickle valve is constructed with a flapper which deeps catalyst from backing up to cyclone dips legs. This flapper periodically opens when the weight of catalyst in the dip leg overcomes the pressure outside the trickle valve and some catalyst is dumped back into the bed. Each dip leg has air purge to prevent plugging During normal operation, catalyst fines are produced in the reactors due to attrition, fines too small to be retained by the cyclones pass out of the reactor with effluent gases. The catalyst inventory should be maintained the good reactor temperature control and maximum conversion to acrylonitrile. The reactor effluent includes unreacted ammonia and propylene, oxygen, nitrogen, acrylonitriel, acetonitrile, Hydrogen cyanide, carbon dioxide, carbon monoxide, water and small quantities of other materials. The reactor effluent gases pass through the effluent cooler where the heat is transferred to the make up boiler feed water or which may be used in reactor steam coils. From the effluent cooler, the partially cooled at 230 OC effluent gases flow to the hot quench in the recovery section .The reactor section also contains the facilities for feeding water to the reactor steam coils and handling the steam generated in the steam coils. 56

Any change in operating conditions in the reactor changes most of the other conditions. Therefore, the total effect of any change is difficult to predict. For instance, an increase in pressure in the reactor reduces the volume of the gases in the reactor, and therefore reduces the velocity of the gases through the catalyst bed. With increased pressure, carbon dioxide production is increased with a resulting rise in reactor temperature and drop in the oxygen content of the effluent stream. The operation of reactor must also be optimized depending on the age and condition of the catalyst and the production rates in the plant. In general, however, conversion to acrylonitrile is favored by low pressure, low temperature, short retention times and good fluidization of the catalyst bed. Proper distribution of the feeds is very important. Any blockage of feed spargers which can seriously affect the propylene conversion to acrylonitrile. 6.1.2 Recovery Section: The major feed stream to recovery section is the reactor effluent gases which is partially cooled at 232 OC is introduced to the bottom of the quench column through a sparger and is adiabatically cooled down to 85 OC in the lower stage of quench column. The quench column is made of two sections. At bottom section, water circulation through proper distributions helps to settle fine catalyst and polymers. Where as at top section un reacted ammonia is neutralized by reacting with sulphuric acid distributed by spray spargers and forms 20-25 weight % Ammonium Sulphate [(NH4)2SO4] solution and maximum of 3.3 weight % polymers. The amount of acid is determined by maintaining pH in the range of 3-4.5. liquid droplets carried upward by effluent gas will knocked down by demister tray above each section and returned to the bottom through demister tray liquid down comer. Solvent water or DM water is sparged at the column top to flush demister tray and water recycled from the heads column decanter and stripper bottom are fed to bottom section for flushing tray. Antifoam is added in circulating water to prevent foaming in the column. From the ammonium sulphate tank it is pumped to Acrylates crystallizer for recovery of ammonium sulphate or incinerated in ACN in incinerator. If ammonia is not

57

neutralized, ammonia may react with acrylonitrile to form various fouling deposits and acid gives polymerization of hydrogen cyanide. To minimize any liquid escaped from the quench column will be controlled in a low flow centrifugal liquid entrainment separator and return to quench column. Then, the effluent gases pass through series of after coolers. Here the effluent gases are cooled by passing cooling water in counter current direction with gases. The cooling water pass through shell side and the gases pass through tube side of after coolers. Finally the gases are cooled from 85 OC to 38 OC. The cooled effluent gases in after coolers have soda ash solution injection along with organic to maintain pH in the range of 6 to 6.5. The oxygen content of the reactor effluent is an important variable and is continuously monitored in the overhead stream leaving the quench column, before entering to the absorber. The product stream exists from the quench column and after cooler coming in the absorber bottom as a feed. The absorber is a tray tower with short section at top and bottom which are provided for heat exchanger. The absorber is tower used to recover acrylonitrile and other organic by absorbing with counter-current flow of water. The absorber and related heat exchangers and vaporizers are an integrated system. A change in operating condition in any part of the absorber system will affect all the other parts. Using less water than this may result in a less of acrylonitrile as overhead with the inert gas stream. Using more water than design result in the need more process water to be circulated handled and a more dilute solution of organics coming from absorber bottom. For this purpose lean water is used. Lean water for absorption is with drawn from the stripper column as side stream which is cooled in heads column reboiler or rich-water-lean water exchanges and then lean water cooler. Lean water temp is controlled approximately 40 OC. The flow of the lean water is controlled by determining the absorber water requirements. It is controlled according to the level on the collection tray of absorber, these changes of the flow in absorber upper circulation. This in turn varies the level at the bottom of the absorber.

58

This warm lean water about 38-40 OC is first enter from the top of the absorber and is cooled by contact with the cold off gases as it passes downward. From first collection tray, the water is removed as absorber side stream and cooled with brine in chiller and passes through ammonia vaporizer where is chilled by Vaporizing ammonia and this chilled water is return to absorber below collection tray. Then, the chilled water flows downward to the absorber bottom for absorbing the acrylonitrile and other organics from gases. The bottom stream from the absorber is rich water. A portion of rich water is removed and cooled with brine in chiller and is chilled by vaporizing propylene by passing through propylene vaporizer. This cold water is return to absorber above feed cooling section. Flow through this circulating system is regulated to maintain a constant temperature 21 OC in the absorber bottom. The unabsorbed gas stream mainly containing unreacted hydrocarbons, oxygen nitrogen, carbon dioxide, carbon monoxide, water and Small amount of acrylonitrile in ppm is vented through the absorber vent stack. The Recovery Column is a tray tower which separates the acrylonitrile from acrylonitrile by extractive distillation. So, it is also known as Acrylo-Aceto Splitter this case solvent water is used as solvent. The acrylonitrile goes overhead, preferable as an acrylonitrile water azeotrope. The acetonitrile goes out at the bottom of the column in dilute water solution. The hydrogen Cyanide in the feed splits; most of hydrogen cyanide goes overhead with acrylonitrile and some goes out the bottom with acetonitrile. The heat required to make the separation in the Aceto-Acrylo Splitter is supplied by the vapors from the upper section of stripper/steam. The overhead product is separated into organic phase and aqueous i.e. water phase in the decanter. The inhibitor HQ is added to the recovery column overhead vapor line to inhibit the formation of polymer. The organic layer containing acrylonitrile, hydrogen Cyanide and water is pumped to the CHN column Acrylo-Aceto Splitter. The water layer is returned to feed.

59

The bottoms product containing acetonitriel in addition too water, hydrogen cyanide and polymers are fed to the Aceto stripper where acetonitriel, hydrogen cyanide and some water are taken as the overhead. The crude acetonitriel is sent to the acetonitriel purification system. The Recovery Column Splitter bottom stream is pumped to the Aceto-Stripper. The stripper is the tray tower which removers acetonitrile and hydrogen cyanide from the bulk of the circulating water, so this water can be reused in the absorber and Recovery column Acetonitrile, Hydrogen Cyanide and some water vapors go overhead to stripper condenser and then to the stripper reflux drum. The reflux drums of equipped with a inert gas purge and is vented to the flare header. Part of condensed vapors is used as reflux; the remainder i.e. crude acetonitrile goes to acetonitrile purification system. Also some part of vapors from upper part of stripper is removed and supply heat to the Recovery column when steam not available. The heat required to make the separation in the stripper is supplied by 3.5 kg / cm2.g steam to a reboiler. Antifoam is added in stream from stripper Recovery column to control foaming in the Recovery Section. Sodium carbonate Solution is added to stripper and to Recovery column overhead line to adjust circulating water pH at these solutions should be maintained within range of 6.0 to 6.5. Sodium Hydroxide Solution should not be used to substitute Sodium carbonate Solution, as run-away polymerization may be initiated by sodium hydroxide. 6.1.3 Purification Section: HCN Column: The crude acrylonitrile from the Recovery Column decanter, composed primarily of acrylonitrile, hydrogen cyanide and water, is pumped too HCN column, as it remove HCN as by product it also called drying column as large amount of water removed from acrylonitrile in this column HCN column is tray column, removed both hydrogen cyanide and water are removed from the acrylonitrile. The overhead vapour, which is approximately 99% Hydrogen Cyanide, goes to an external overhead condenser where it is condensed. The condensed liquid is partly refluxed to 60

the column and partly sent to HCN purification. Any uncondensed vapor passes through a liquid knockout drum and goes to the Incinerator or Flare. Acetic acid is added to at top of column to prevent formation of hydrogen cyanide polymers. The hydrogen cyanide vapors are condensed on the tube side in a downward flow. Sulphur dioxide is added to the HCN vapor line to help minimize hydrogen cyanide polymerization in the vapor phase. In order to remove water, a total liquid draw off intermediately and is cooled is sidestream cooler where it is cooled to 40 OC. This stream then goes to decanter when a phase separation takes place. One phase is predominately water phase the other phase organic phase i.e. acrylonitriel. The water phase is pumped from decanter to bottom of quench column and alternately this stream goes with ammonium sulphate stream as waste water. The acrylonitrile phase is sent back to the HCN column via Heat exchanger Hydroquinone (HQ) as an acrylonitrile polymerization inhibitor is added into the organic phase of HCN column decanter. The lower amount of cyanides in the HCN column decanter, the better will be the water removal capability of the drying section of this column. 6.1.4 Product Column: The bottoms of HCN column /drying column are pumped as feed to product column. The product column is a vacuum column that separates heavier and lighter from the acrylonitrile. The column is equipped with an overhead condenser and a vent condenser for removing non-condensable. The vent condenser is equipped with vacuum ejector with medium pressure steam. Most of the overhead stream is reflux to the top of the column and the remainder is normally recycled to Recovery column feed or Recovery column decanter. The recycle to Recovery column decanter removes low boiling impurities from the product column and prevents them from accumulating in the top of the column. Heavy products of reaction and polymer in the purification system are removed via the product column bottoms stream. To remove solid polymer, the bottom stream is filtered before the bottoms pump. The net bottoms product flows to the Recovery column for recovery of products.[the overhead

61

product and bottoms of product column again feed to Recovery column for recover acrylonitrile So it is also known as Recovery column. The product acrylonitrile is removed from top and is pumped via the cooler to product rundown tank. Polymerization inhibitors Hydroquinone (HQ) Methyl Ether Hydroquinone (MEHQ) are added into rundown storage tank ages. 6.1.5 Aceto Column: Crude acetonitrile coming from stripper top having around 1-2% HCN is taken in topped crude tank and HCN is killed by digestion by formaldehyde and caustic in treating kettle. The overhead material is chemically dried by anhydrous calcium chloride and for the final purification batch distillation is operated. 6.2 REVAMP OF ACRYLONITRILE PLANT: Revamp of acrylonitrile plant is aimed at (1) Increasing capacity of plant. (2) Reducing water consumption of the plant. (3) Steam saving. (4)It involve reactor cyclone, air grid, hydrocarbon sprager modification and change in internals of Quench column and absorber. 6.3 AUXILIARY CHEMICALS ADDED: Some chemicals added in process streams with their significance are given as below. 6.3.1 Inhibitors: There are three inhibitor solutions are used for prevention of polymerization of acrylonitrile MEHQ or Ammonia is used to inhibit the final product acrylonitrile. HQ is used to inhibit acrylonitrile polymerization in various location in the plant, except I the final product rundown tank and the tip of product column. These materials are toxic and must be handled accordingly. 1) Methyl Ether of Hydroqu9oone (MEHQ): This solution should be weight percent MEHQ in Acrylonitrile. For preparation of solution, acrylonitrile is added to mixing tank. Then MEHQ is dumped into mixing tank.

62

2) AQUA Ammonia This solution should be 30 weight percent ammonia in water. Treated water is charged to the aqua Ammonia drum. When a definite level has been established in the drum, the pump is started to circulate the water through the aqua ammonia cooler, having brine flow, Ammonia vapors are slowly added to the drum. Circulating water stream will dissolve Ammonia according to vapor pressure of Ammonia t that temperature. The temperature is adjusted to give 30% Ammonia solution. As the inhibitor solution is consumed, additional water and ammonia vapors are slowly and continuously added to the drum for maintaining equilibrium. 3) Hydroquinone (HQ): This solution should be 6.5 weight percent HQ in acrylonitrile. This solution should be prepared in similar way as For MEHQ. Hydroquinone is less soluble in acrylonitrile than MEHQ. 6.3.2 Antifoam Agent: Antifoam agent used to prevent foaming in the quench column and the recovery column section circulating water system. Betz foam ± Troll LT or Betz DL -300-82 is example of such antifoam agent. It is added into water and diluted. It is charged to the antifoam tank and then supplied with antifoam injection pump. 6.3.3 Soda Ash Solution: Soda Ash solution should be 10 weight percent sodium carbonate in water. Condensate is added to the mixing tank. Mixer is turned on and enough sodium Carbonate is added to make the solution. Soda Ash solution is used to adjust pH of circulating water and minimizing corrosion in the systems. It is added in stripper tray and recovery column overhead line down stream of the condenser. 6.3.4 Acetic Acid: Acetic Acid solution should be 50 weight percent acetic acid in water. Add concentrated Acetic Acid to mixing tank and then slowly add condensate to the tank. Mix contents with the agitator. Continue adding condensate until the desired acid concentration is achieved. Acetic Acid is used in HCN column condenser inlet for preventing polymerization of hydrogen Cyanide. 63

6.3.5 Sulphur Dioxide: Sulphur Dioxide is added t the HCN vapor line to help minimize HCN polymerization in the vapor phase.

64

CHAPTER 07: MATERIAL BALANCE

Material balances are the basis of process design. A material balance taken over complete process will determine the quantities of raw materials required and products produced. Balances over Individual process until set the process stream flows and compositions. The general conservation equation for any process can be written as Material out = material in + generation ± consumption + accumulation

For a steady state process the accumulation term is zero. If a chemical reaction is taking place a particular chemical species may be formed or consumed. But if there is no chemical reaction, the steady state balance reduces to,

Material out = Material in

A balance equation can be written for each separately identifiable species present, elements, compounds and for total material. 7.1 BASIS: Basis: 70, 000 tons/annum. The process is planned and developed as a continuous process. A plant is operated for 24 Hours per day and 330 per year. Capacity

= 70,000 tons/annum = 70,000 / (330 x 24) = 8838.38 kg/hr

7.2 CATALYST PERFORMANCE: As using catalyst M9MC given by Sohio, the conversion of C3H6 is taken as, 80%

to

ACN

2.3%

to

Aceto

5.9%

to

HCN 65

1.5%

to

acrylic Acid\

0.7%

to

Acrolein

0.2%

to

Acetic acid

5.1%

to

CO2

2.9%

to

CO2

1.4%

to

Unconverted C3H6

7.3. MOLECULAR WEIGHT: in kg / kgmole Table-7.1 Molecular weight in kg / kgmole Acrylonitrile [C2H3CN]

:

53.03

Acetonitrile [CH3CN]

:

41.02

Hydrogen Cyanide [HCN]

:

27.01

Propylene [C3H6]

:

42.03

Ammonia [NH3]

:

17

Oxygen [O3]

:

32

Nitrogen [N2]

:

28

Acrolein [CH2CHCHO]

:

56.03

Carbon monoxide [CO]

:

28.01

Water [H2O]

:

18

Carbon Dioxide [CO2]

:

44.01

Acrylic Acid [CH2CHCOOH]

:

72.03

Acetic Acid [CH3COOH]

:

60.02

Assume there is 1% loss of ACN as in any outlet stream or which may polymerized. So, actual capacity of plant is 8927.66 kg/hr. Assume no catalyst mass coming out from the reactor. Let, Air / C3H6 = 6.75 and NH3 / C3H6 = 0.42 Both ratios are on the weight basis.

66

7.4 REACTOR: [1]Acrylonitrile: C3H6 + 3/2 O2 + NH3 (42.03)

(48)

CH2 = CHCN + 3H2O

(17)

(53.03)

(54)

Propylene required (for 80% conversion to ACN) = (8927.66 x 42.03) / 53.03 = 7075.80 kg/hr (for 80% conversion) Actual C3H6 used

= 7075.80 / 0.80 = 8844.75 kg/hr

[2] Hydrogen Cyanide: C3H6 + 3NH3 + 3O2

3HCN + 6H2O

(42.03)

(81.03)

(51)

(96)

(108)

Hydrogen Cyanide produced = (0.059 x 8844.75) x (81.03) / 42.03 = 1006.06 kg/hr [3] Acetonitrile: C3H6 + 3/2 O2 + 3/2 HN3 (42.03)

(48)

3/2CH3CN + 3H2O

(25.5)

(61.53)

Acetonitrile produced = 297.81 kg/hr [4] Acrolein: C3H6 + O2

CH2 = CHCOOH + H2O

(42.03) (32)

(56.03)

(18)

Acrolein produced = 82.53 kg/hr [5] Acrylic Acid: C3H6 + 3/2O2 (42.03)

CH2 = CHCOOH + H2O

(48)

(72.03)

Acrylic Acid produced =227.37 kg/hr 67

(18)

(54)

[6] Acetic Acid: C3H6 + 3/2O2 (42.03)

3/2CH3COOH

(48)

(90.03)

Acetic Acid produced = 37.89 kg/hr [7] Carbon Dioxide: C3H6 + 9/2O2

3CO2 + 3H2O

(42.03)

(132.03)

(144)

(54)

Carbon Dioxide produced = 1417.00 kg/hr [8] Carbon Monoxide: C3H6 + 3O2

3CO + 3H2O

(42.03) (96)

(84.03)

Carbon Monoxide produced = 512.81 kg/hr [9] Ammonia: From reaction [1], [2] and [3]. Ammonia required = 3618.60 kg/hr now, NH3 / C3H6 = 0.42 Therefore, NH3 actual input = (0.42) x (8844.75) = 3714.80 kg/hr NH3 consumed = 3618.60 kg/hr NH3 excess i.e. unreacted = 3714.8 ± 3618.60 = 96.20 kg/hr [10] Water: From reaction [1] to [8] Water formed = 11685.68 kg/hr

68

(54)

[11] Air: From reactions [1] to [8] Oxygen required = 11855.29 kg/hr Now, Air contains 23.3% O2 & 76.7% N2 on weight basis. Air required

= 11855.29 / 0.233 = 50881.17 kg/hr

Now, Air / C3H6

= 6.75

Air in

= (6.75) x (8844.75) = 59702.06 kg/hr

O2 in = 13910.58 kg/hr

(23.3 wt% of air)

N2 in = 45791.48 kg/hr

(76.7 wt% of air)

O2 consume d

= 11855.29 = 13910.58 ± 11855.29

O2 excess

= 2055.29 kg/hr N2 out

= 45791.48 kg/hr

ACN

= 8927.66 kg/hr Table-7.2 Material balance over Reactor: Component Material in, kg/hr Material out, kg/hr Propylene

8844.75

--

Ammonia

3714.80

--

O2

13910.58

--

N2

45791.48

45791.48

Acrylonitrile

--

8927.66

Acetonitrile

--

297.81

HCN

--

1006.06

Acrolein

--

82.53

Acetic acid

--

37.89

Acrylic Acid

--

227.37

69

CO2

--

1417.00

CO

--

512.81

Water

--

11685.68

Total

72261.61

72261.61

7.5 QUENCH COLUMN: Input stream = Effluent from Reaction via effluent cooler Two section provided in Quench column. Water is circulated over both section from stripper i.e. water in = Water from Aceto stripper = 9414.96 kg/hr Excess NH3 = 96.20 kg/hr Excess NH3 React with H2SO4: Reaction: 2NH3 + H2SO4 (34.02)

(NH4)2SO4

(96.06)

(138.08)

H2SO4 in = (96.20 x 98.06) / 34.02 = 2777.29 kg/hr let 10% excess Total H2SO4 added = 305.02 kg/hr Excess H2SO4 = 27.73 kg/hr Other by product like, Acrylics Acid, A.A, Acrolein, some ACN are polymerized and catalyst carry over also taken out with bottom stream.

70

Table-7.3 Material balance over Quench Column: Component

Material in, kg/hr

Material out , kg/hr

Acrylonitrile

8927.66

8927.66

Acetonitrile

297.81

297.81

HCN

1006.06

1006.06

Acrolein,Acetic cid,Acrylic Acid

347.79

--

Waste

--

347.79

CO2

1417.00

1417.00

CO

512.81

512.81

Water

11685.68(as feed)

15864.07(at top)

9414.96(as Lean Water)

5236.57(at bottom)

33609.77

33609.77

Total

7.6 ABSORBER: Assumption: Off-gases containing CO, CO2, N2, unreacted O2, unreacted C3H6. Not absorbed in water and are remove from top of column. Also HCN of 0.5% in is removed in it i.e., = (0.005) (1006.06) = 5.03 kg/hr ACN out at top as off gases = 54 kg/hr Off ± gases contains Some entrained water = 108.59 kg/hr and all CO2,CO,N2,Unconverted C3H6 Data: Solubility of Acrylonitriel in water, wt% At 400C

7.9%

0

7.5%

0

7.3%

At 30 C At 20 C

71

Top of absorber have temperature 400C and at 400C water added at top. Feed at bottom also 400C and feed enter at bottom is also at 400C. but about 250C maintain in column using side stream cooling. So, take solubility of Acrylonitrile around 7.7 wt% in water Therefore, for 8927.66 kg/hr ACN is, Water required for absorb ACN = (8927.66 x92.3) / 7.7 = 107015.98 kg/hr Acetonitrile& HCN have infinite solubility in water for absorption. Lean water added NJKU«««««««««««>)URP(QHUJ\%DODQFH@ So Total water added for absorption is water with feed and lean water.

7.7 RECOVERY COLUMN AND DECANTER: RECOVERY COLUMN: We have Separation of Acetonitrile as bottom and Acrylonitrile as overhead using extractive distillation using water as solvent. All Acrylonitrile and all HCN feed separated as overhead. Also, Separation such as, total Aceto ±98% to bottom (of Inlet feed) and 2% as overhead ( of Inlet feed) Aceto at bottom

= (297.81) x (0.98) = 291.85 kg/hr

Aceto at top

= 297.81 x 0.02 = 5.96 kg/hr

Now, bottom has 1.7% dilute solution of Aceto of Water with Aceto at bottom

= (291.85 x 100) / 1.7 =17167.64 kg/hr

Water as overhead

= 8476.39 kg/hr

DECANTER: Now, consider top stream have is separated out in decanter in aqueous (water) phase and organic (ACN) phase. Separate out 95% of aqueous phase as water in decanter. 72

Water goes with organic phase = 5% of top stream = 0.05 x 8476.39 = 414.5 kg/hr Water removed

=8476.39 - 414.5 =8061.89 kg/hr

7.8 ACETO COLUMN: Total Acetonitrile in feed separated as over head Acetonitriel is overhead

= 291.85 kg/hr

In Aceto-stripper, the total Acetonitrile go as overhead with water and get 70% acetonitrile as overhead. Acetonitriel is overhead

= 291.85 kg/hr (70%)

Water with Acetonitrile as overhead = 125.08 kg/hr (30%) = 17167.64 ± 125.08

Water out a bottom

= 17042.56 kg/hr 7.9 HCN COLUMN: The feed of HCN column is generally ACN & HCN with little amount of H2O and Acetonitrile. Hence, it can be treated as binary distillation considerably HCN & ACN alone. From feed, all ACN and 99% pure HCN is recovered from top. F=D+W 10295.15 = D + W Where, F related to feed D related to distillate (overhead) products W related to bottom products For HCN Balance: F XF = D XD+ W XW 1001.03

= D (0.99) + W (0.01)

Solving above two equations for D & W D

= 1001.02 kg/hr 73

W

= 9294.13 kg/hr

Top product stream: HCN Recovered from top = 991.02 kg/hr ACN as to product = 10.0 kg/hr The bottom crude ACN Stream has, ACN

= 8863.66 kg/hr

HCN

= 10.01 kg/hr

H2O

= 414.5 kg/hr

Aceto

= 5.96 kg/hr

7.10 PRODUCT COLUMN: It is the column to get pure ACN from crude ACN. Recover 99.7% of feed as top stream along as Product Acrylonitrile. ACN as overhead product = (8863.66) x (0.997) = 8838.38 kg/hr Also, Bottom stream contains Heavy ends Polymer mass which from during the whole process from the small amount of Acrylonitrile (25.28 kg/hr), Acetonitrile (5.96 kg/hr), and water (414.5kg/hr).

74

CHAPTER-08: ENERGY BALANCE Let, the reference temperature = 25oC 8.1 PREHEATING OF REACTOR: To initiate the exothermic reaction, it is necessary to heat the reactants, i.e. air, propylene and ammonia is to reactor temperature 425oC before reaction. [Feed at high pressure/ temperature lower than 425oC assume have same enthalpy at 425oC, atm.] Energy required for preheat the reactants, Table-8.1 Components and its properties Component

Kg/hr

Mole.wt.

Kg

Cp.at

ni.cpi

o

mol/hr

425 C

C3H6

8844.75

42.03

210.44

28.3

5955.42

Ammonia

3714.80

17

218.52

10.05

2196.10

Air

59702.06

29

3300.07

7.21

23793.51

Ȉni Cpi = 31945.04 ǻ7

= 425-25=4200 C

Energy Supplied to preheat reactant Ȉni Cpi. ǻ7 = 13416915 Kcal This energy supplied by the Heater. 8.2 ENERGY BALANCE AROUND REACTOR: Reactants in at 4250 C

Products out at 4250 C

At 250 C

At 250 C

(a)Enthalpy in with reactants = 13416915 Kcal (b)Total Heat of Reaction: Assume, Formation of Acrolein, Acetic acid, Acrylic acid is very very small and it is neglected 75

(i) C3H6 + NH3 + 1.5O2

CH2CHCN + 3H2O

(ii) 2/3C3H6 + NH3 + O2

CH3CN + 2H2O

(iii) 1/3C3H6 + NH3 + O2

HCN + 2H2O

(iv) C3H6 + 4.5O2

3CO2 + 3H2O

(v) C3H6 + 3O2

3CO + 3H2O

Heat of formation at 25oC Acrylonitrile

liquid

36.2

Acetonitrile

gas

19.81

Hydrogen Cyanide

gas

31.1

Carbon Table-8.2 Components and its properties Compound

State

Kcal/gmol

Propylene

gas

4.88

Ammonia

gas

-11.0

Water

gas

-57.8

Acrylonitrile

gas

45.37

Dioxide

gas

-94.05

Carbon Oxide

gas

-32.81

Heat of reaction = >Ȉ KHDWRIIRUPDWLRQRISURGXFWV @± >Ȉ KHDWRIIRUPDWLRQRIUHDFWDQWV @ Heat of reaction of Acrylonitrile = [(45.37) + 3(-57.8)] ± [4.88 + (-11.0)] = - 132.91 Kcal/gmol = - 132910 Kcal/kgmole Heat of reaction of Hydrogen Cyanide = [3(31.1) + 6(-57.8)] ± [4.88 + 3(-11.0)] = -291.38 Kcal/gmol = - 291380 Kcal/kgmole 76

Heat of reaction of Acetonitrile = [1.5(19.80) + 3(-57.8)] ± [4.88+1.5(-11.0)] = - 165.07 Kcal/gmol = - 165070 Kcal/kgmole Heat of reaction of Carbon Dioxide = [3(- 94.05) + 3(-57.8)] ± [4.88] = - 460.43 Kcal/gmol = - 460430 Kcal/kgmole Heat of reaction of Carbon Oxide = [3(32.81) + 3(-57.8)] ± [4.88] = - 276.71 Kcal/gmol = - 276710 Kcal/kgmole 7RWDOǻ+

Ȉniǻ+R =57130676.23 Kcal

(c) Enthalpy out with products: Table-8.3 Enthalpy out with products Component

Kg/hr

Mol.

K

Wt.

Mol/hr

Cpi at 4250C

ni.cpi

ACN

8927.66

53.03

168.35

24.88

4188.54

Aceto

297.81

41.02

7.26

17.63/19.86

144.58

HCN

1006.06

27.01

37.27

9.95

370.84

CO2

1417.00

44.01

32.2

10.05

323.61

CO

512.81

28.01

8.84

7.44

65.77

H2O

11685.68

18

649.2

8.45/7.25

4706.7

C3H6

123.83

42.03

2.95

28.3

83.38

NH3

96.20

17

5.66

9.28

52.51

O2

2055.29

32

64.23

7.45

478.50

N2

45791.48

28

1635.41

7.1

11611.41

77

Ȉni Cpi = 22025.84 ǻ7 -25=4200 C Enthalpy out with products: Ȉni Cpi ǻ7 = 22025.84 x 420 = 9250852.80 Kcal (d) Enthalpy removed by the coolant = Enthalpy of Reactant at 250C ± Heat of reactions ± Enthalpy of product 4250C = (- 13416915) - (- 57130676.23) - (9250852.80) = - 61296738.43 Kcal (e) Coolant required: This heat is removed using steam at 1100C which is superheated up to 3700C. Msteam Cpsteam ǻ7 .FDO [Msteam] x [1] x [370-110] = 61296738.43 Kcal Msteam = 3064836.92 kg/hr This is the amount of steam required to removed the heat at evolved in the reactor. 8.3 ENERGY BALANCE OVER PRODUCT GAS COOLER: Inlet temperature of gases = 4250C Outlet temperature of gases = 2300C (a) Enthalpy in with gases = 9250852.80 Kcal (b) Enthalpy out with gases: Table-8.4 Enthalpy out with gases Component

Kg/hr

Mol.

KMol/hr Cpi at 2300C

ni.cpi

Wt. ACN

8927.66

53.03

168.35

21.91

3688.55

Aceto

297.81

41.02

7.26

17.43

126.54

HCN

1006.06

27.01

37.27

9.35

348.47

CO2

1417.00

44.01

32.2

10.03

331.66

78

CO

512.81

28.01

8.84

7.13

63.03

H2O

11685.68

18

649.2

7.47

4849.52

C3H6

123.83

42.03

2.95

22.7

66.97

NH3

96.20

17

5.66

9.28

52.53

O2

2055.29

32

64.23

7.27

466.95

N2

45791.48

28

1635.41

7.0

11447.87

Ȉni Cpi = 21773.55 ǻ7 -25=2250C Enthalpy out with gases

Ȉni Cpi ǻ7 = (21773.55) x (225) = 4899048.75 Kcal

(c)Coolant Required: Steam required to cool the effluent at temperature 1100C which is heated upto heated upto 2000C temperature. 0VWHDP&SVWHDPǻ7 = (Enthalpy out with gases) ± (Enthalpy out with gases ) = (9250852.80) - (4899048.75) = 4351804.05 Kcal [Msteam] x [1] x [200-110] = 4351804.05Kcal Msteam = 48353.38 kg/h 8.4 ENERGY BALANCE AROUND QUENCH COLUMN: (a) Enthalpy in with product gases: = 489 9048.75 Kcal (b) Enthalpy due to heat of reaction: In the Quench column the neutralization of ammonia using Sulphuric acid take place. 2NH3 + H2SO4 (34.02)

(96.06)

(NH4)2SO4 (138.08)

ǻ+R = -76662 Kcal / Kmol Ammonium Sulphate Amount of (NH4)2SO4 formed = 390.72 kg/hr[from Material Balance] Total heat liberated due to reaction 79

= (-76662) x (390.72/138.08) = - 216927.7 Kcal (c) Enthalpy out with gases [at top]: Table-8.5 Enthalpy out with gases [at top] Component

Kg/hr

Mol.

K

Wt.

Mol/hr

Cpi at 850C

ni.cpi

ACN

8973.66

53.03

167.35

19.78

3309.78

Aceto

297.81

41.02

7.26

17.21

12.94

HCN

1006.06

27.01

37.27

8.88

330.96

CO2

1417.00

44.01

32.2

9.22

296.88

CO

512.81

28.01

8.84

6.98

61.70

O2

2055.29

32

64.23

7.02

450.89

N2

45791.48

28

1635.41

6.96

11382.45

H2O

11864.07

18

881.34

4.73

881.34

C3H6

123.83

42.03

2.95

17.6

51.92

ȈQL&SL  ǻ7 -25 = 60 0C Enthalpy RXWZLWKJDVHV  ȈQL&SL ǻ7= 1006731.6 Kcal (d) Enthalpy out with bottom stream:  ȈQL&SL ǻ7 = (6.5 x 390.72) + (1 x 1762) [Cp of (NH4)2SO4 =6.5 Kcal /kg] = 258100.80 Kcal Heat carried away by H2SO4 polymer neglected in bottom stream as it is very very small. (e) Heat required liquefying the water vapor which out from bottom and cool from 230 to 85 0C = (to cool water vapor to 230 to 100 0C) + (Exchange of latent heat of vaporization) + (cool liquid water from 100 to 850C) = (5236.57 x 1 x 130) + (5236.57 x 550) + (5236.57 x 1 x 15) 80

=3639416.15 Kcal Enthalpy removed = (a) - (b) - (c) - (d) - (e) = 211727.9 Kcal So, water added 0VWHDP&SVWHDPǻ7 = 211727.9 Kcal [Msteam] x [1] x [23] = 211727.9 Kcal Msteam = 9414.96 kg/hr This is water added to quench column.

8.5 ENERGY BALANCE AROUND AFTER COOLER: Inlet temperature of gases

= 850C

Outlet temperature for gases

= 400C

Boiling point of ACN

= 780C

Boiling point of Aceto

= 820C

Therefore, at 400C temperature, ACN and Aceto will get condensed. (a) Heat in with gases = 1006731.6 K cal (b) Heat required to condense ACN: = MACNȜACN = (8973.66/53.03) x (780) = 130519.61 Kcal (c) Heat required to condesese Aceto: = MACETOȜ ACETO = (297.81/41.02) X (711) = 5161.94 Kcal (d) Enthalpy out with the mixture:

81

Table-8.6 Enthalpy out with the mixture Component

Kg/hr

Mol.

K

Wt.

Mol/hr

Cpi at 400C

ni.cpi

ACN(L)

8973.66

53.03

167.35

26.87

4496.16

Aceto(L)

297.81

41.02

7.26

21.06

156.82

HCN

1006.06

27.01

37.27

8.66

322.76

CO2

1417.00

44.01

32.2

8.9

286.58

CO

512.81

28.01

8.84

6.97

61.61

C3H6

123.83

42.03

2.95

15.85

46.76

O2

2055.29

32

64.23

7.0

449.61

N2

45791.48

28

1635.41

6.96

13470.45

H2O(L)

11864.07

18

881.34

18

15864.12

Ȉni Cpi = 35154.87 ǻ7 -25=150C Enthalpy out with gases Ȉni Cpi ǻ7 = (35154.87) x (15) = 527323.05 Kcal (e) Enthalpy absorbed by the water added = (a) ± (b) ± (c) ± (d) = 343727.00 Kcal 0ZDWHU&SZDWHUǻ7 Let, cooling water temeperature is 300C is added and out let temperature is 40oC. Mwater x (1) x (10) = 343727.00 Mwater = 34372.70 kg So, 34372.70 kg cooling water required. 8.6 ENERGY BALANCE AROUND ABSORBER AND HEAT EXCHANGES: Inlet temperature of Absorber

= 400C

Outlet temperature of Absorber

= 400C [at top]

Maintain temperature in absorber

= 250C 82

(a) Enthalpy in with feed mixture: = 527323.05 Kcal (b) Enthalpy out with unabsorbed gases from top: Table-8.7 Enthalpy out with unabsorbed gases from top Component

Kg/hr

Mol.

K

Wt.

Mol/hr

Cpi at 400C

ni.cpi

CO2

1417.00

44.01

32.2

8.9

286.58

CO

512.81

28.01

8.84

6.97

61.61

O2

2055.29

32

64.23

7.0

449.61

N2

45791.48

28

1635.41

6.9

11284.33

123.83

42.03

2.95

15.85

46.76

H2O(G)

11864.07

18

6.03

16.2

97.69

HCN

1006.06

27.01

0.18

8.66

1.56

C3H6

Ȉni Cpi = 1228.14 ǻ7 -25=150C Enthalpy out with unabsorbed gases  Ȉni Cpi ǻ7 =183422.1 Kcal (C) Enthalpy out with bottom stream: Table-8.8 Enthalpy out with bottom stream Component

Kg/hr

Mol.

K

Wt.

Mol/hr

Cpi at 300C

ni.cpi

CAN (L)

8927.66

53.03

167.33

26.57

4445.96

Aceto (L)

297.81

41.02

7.26

21.34

154.93

HCN

1006.06

27.01

37.27

8.06

320.52

H2O (L)

22644.04

18

1424.66

18

25643.88

Ȉni Cpi = 30565.29 ǻ7 -25 = 50C Enthalpy out with unabsorbed gases  Ȉni Cpi ǻ7 83

= 152826.45 Kcal (d) Enthalpy in with lean water: Mlean water CpH2O ǻ7 = 9888.56 x (1) x (40 -25) = 148328.4 Kcal (e) Enthalpy removed by cooling system: Heat evolved = [Heat in with feed + Heat with lean water] ± [heat out with gases + Heat out with bottom product] = [(a) + (d) ] ± [ (b) + (c) ] =339402.90 Kcal This heat removed by cooling/chilling system. Also this cooling/ chilling system used by cooling/ chilling side stream from absorber to maintain temperature of absorber around 250C for better absorption. Heat exchanger 1: It is rich water/solvent water exchanger. It increases the temperature of bottom rich water from 30 to 400C. Msolvent water CpH2O ǻ7

= Heat out ± Heat in

Msolvent water x (1) x (80-50)

= 459294.3-15826.45

Msolvent water

= 10215.59 kg/hr

Heat exchanger 2: It is rich water (40oC) /Let water (95oC) exchangers. It preheat the rich water upto 80oC for feeding recovery cooled. (No vaporization assume) Mlean water CpH2O ǻ7

= Heat out ± Heat in

Mlean water x (1) x (90-85)

= 148328.43

Mlean water

= 9888.56 kg/hr

8.7 ENERGY BALANCE AROUND RECOVERY COLUMN: (a) Heat in with feed= 148328.43 K cal = F HF Temperature of column = 85 0C (at top) (b) Load on reboiler, Qb: Feed at 800C, It is Saturated liquid. 84

Load on reboiler, Qb = [for vaporization of ACN, Aceto, H2O as distillate] + [H.T. in Remaining comp. coming from bottom] ȈmȜȈni Cpi. ǻT = [(8873.66 x 147) + (5.96 x 173.68) + (8476.39 x 550)] + [(177.8+17358.39) x (110-80)] = 6518895.503 Kcal /HWVWUHDPLVXVHGLQUHERLOHUDWDWPKDYLQJȜ stream = 550 K cal/kg Steam required in reboiler Mstream Ȝ stream = 6518895.503 M stream = 11852.54 kg/hr (c)Enthalpy out with Distillate: [DHD] Table-8.9 Enthalpy out with Distillate: [DHD] Component

Kg/hr

Mol.

K

Wt.

Mol/hr

Cpi at 850C

ni.cpi

CAN (G)

8927.66

53.03

168.35

16.77

2806.12

Aceto (G)

297.81

41.02

0.15

13.5

2.03

HCN (G)

1006.06

27.01

37.27

9.2

320.88

H2O (G)

22644.04

18

470.91

6.19

2914.43 Ȉni Cpi = 6065.97 ǻ7 -25 = 600C

(QWKDOS\RXWZLWKGLVWLOODWH Ȉni Cpi . ǻ7 = 363958.2 Kcal = D HD (d) Enthalpy out with Bottoms (W.HW) Table-8.10 components and their mole fraction Component

Kg/hr

Mol.

K

Wt.

Mol/hr

Cpi at 850C

ni.cpi

Aceto

291.85

41.02

7.115

24.99

177.8

Water

17167.64

18

955.76

18.02

17358.39

85

Ȉni Cpi = 17536.19 ǻ7 -25 = 85 oC Enthalpy out with bottoms Ȉni Cpi . ǻ7 = 1490576.28 Kcal = W HW (e) Condenser load: Top product condensed and then cools upto 40OC P&Sǻ7PȜP&Sǻ7

Heat removed O

Boiling point ACN (78 C), Aceto (82OC), So, take 85OC as saturated liquid as feed.HCN is gas from 85 OC to 40OC and Water 85OC liquid. Heat removed

= [(8873.66 x 147) + (5.96 x 173.68)+(1001.03 x 210.23)]

+ [(167.33 x 26.3)+(0.15 x 21.91)+(37.27 x 8.7)+(470.91 x 18)] x (85 - 40) =1737702.92 Kcal Cooling water required 0FZ&Sǻ7

= 1737702.92

Mcw x (1) x (10) = 1737702.92 Mcw

= 173770.3 kg/hr

8.8 ENERGY BALANCE ON DECANTER: Enthalpy in Decanter Table-8.11 Enthalpy in Decanter Component

Kg/hr

Mol.

K

Wt.

Mol/hr

Cpi at 400C

ni.cpi

CAN (l)

8973.66

53.03

167.33

26.87

2896.16

Aceto (l)

5.95

41.02

0.15

21.6

3.24

HCN (l)

1001.03

27.01

37.27

8.66

322.76

H2O (l)

8476.39

18

470.91

18

8476.38 Ȉni Cpi = 13298.54

0

Enthalpy in Decanter ǻ7 -25 =15 C 86

>Ȉni Cpi @ǻ7 =199478.03 Kcal Enthalpy out with organic phase = (4496.16+3.24+322.76+414.5) x (40-25) = 78987.3 Kcal Enthalpy out with aqueous phase = (8061.9 x 15) = 120928.5 Kcal 8.9 ENERGY BALANCE ON ACETO STRIPPER: The feed at saturated liquid (a) Heat in = F HF = 78987.3 K cal ȈPȜȈni Cpi. ǻ7

(b) Load on reboiler, Qb:

= ((291.85/4 2.03) x 7476.43) + ((125.08/18) x 550) + (17042.56 x 18 x 10) = 3123397.9 Kcal /HWVWUHDPLVXVHGLQUHERLOHUDWDWPKDYLQJȜ stream = 550 K cal/kg Steam required in reboiler Mstream Ȝ stream = 31233097.9 Kcal M stream = 5678.91kg/hr (c) Enthalpy out with Distillate: [DHD] R = 1.5 L = 1.5 D

= (1.5) (416.93) kg = 625.40 kg

G = L+ D

= 1042.33 kg

*Ȝ

= (1042.33) (5398.5) = 5627019.55 K cal

Mcw.Cp ǻ7

= 5627019.55 kg/hr

Mcw x 1 x 10

= 5627019.55 kg/hr

Mcw

= 562701.96 kg/hr

D HD

>Ȉ0L[email protected]ǻ7 87

= [((291.85/42.03) x 17.21) + ((125.08/18) x 18)] x (85-25) = 14675.02 Kcal W HW >Ȉ0L[email protected]ǻ7 =17042 x 18 x (120-25) = 29142777.6 Kcal 8.10 ENERGY BALANCES ON HCN COLUMN:Enthalpy input with feed = 78987.3 Kcal Top temperature= 25oC Bottom temperature = 80oC The feed at saturated liquid (a) Heat in = F.HF = 78987.3 K cal ȈPȜȈni Cpi. ǻ7

(b) Load on reboiler,Qb:

= [(1001.03 x 210.37) ] + [(1697.33+28.22) + (0.15 x 22.12) + (23 x 17.92)] x (80-40) = 2143151.90Kcal /HWVWUHDPLVXVHGLQUHERLOHUDWDWPKDYLQJȜ stream = 550 K cal/kg Steam required in reboiler Mstream Ȝ stream = 2143151.90 M stream = 3896.64 kg (c)Enthalpy out with Distillate: [DHD] L/D = R R = 1.1 D = 991.01 L = 1090.11 kg/hr G=L+D = 2081.12 kg/hr mbrine.Cpi ǻ7 *Ȝ mbrine x (1.6) x (5) = (2081012 x 6008.09) mbrine = 1562944.53 kg F HF = 78987.3 K cal 88

D HD = m.Cp ǻ7 ǻ7 , as reference temperature is 25, and distillate has W.HW temperature.) W.HW = [(167.33 x 29.24)+(0.37 x 8.87) + (23.03 x 19.31)+(0.15 x 23.62)] x (80-25) = 293934.30 Kcal 8.11 ENERGY BALANCE ON ACN COLUMN: Feed is saturated liquid at 850C (a) Heat in = F.HF = K cal (b) Load on reboiler, Qb: ȈPȜȈni Cpi. ǻ7 = [(167.33 x 7801.29)] + [neglected- as very less ] = 1305389.85Kcal /HWVWUHDPLVXVHGLQUHERLOHUDWDWPKDYLQJȜ stream = 550 K cal/kg Steam required in reboiler Mstream Ȝ stream = 1305389.85Kcal M stream = 2373.44 kg/hr (c)Enthalpy out with Distillate: [DHD] L/D = 1.7 L = 1.7[8838.38]

= 15025.25

G=L+D

= 23863.63

*Ȝ

= (23863.63) x (7801.29) = 186167098.1 K cal

mcwCpi ǻ7 .FDO (mcw) (1) (10) = 186167098.1 mcw= 18616709.80 kg/hr = Cooling Water flowrate D.HD >Ȉ0L[email protected]ǻ7

= [(8838.38/53.03) x 19.7 x (25)] = 82083.77 Kcal

W.HW

>Ȉ0L[email protected]ǻ7 = [((35.28/53.03) x 19.7) + ((10.01/42.03) x 17.2) + ((414.5/18) x 18)] x (75) = 32377.5 Kcal

89

Designing for half coil.jacket. p

= 40 kg/cm2

pd

= 40 x 1.05 kg/cm2

fa

= 980 Kg/cm2

di

= 500 mm

Now, tc=

pdi + Ca 2fa

= 14 mm (standard) Checking for total circumferential shear : fps=

p2di p1Di + 2ts 4tc+2.5ts

= 610.11 kg/cm2 which is less than 980 Kg/cm2 Hence, it is safe 9.1.2 Checking tower height for various external and internal loads Data Height of the reactor

= 13.8 + 2

= 15.8 m

Internal diameter of the reactor = 4.6m Thickness of shell

= 6mm

Design pressure

= 0.82 Kgf/cm2

J

= 0.85

MOC : Carbon steel Specific gravity

= 7.7

Corrosion allowance

= 3 mm

(1)

Axial stress due to pressure

fap

=

0.82 x 4600 4x3 = 314.33 Kgf/cm2

92

CHAPTER-10: PROCESS CONTROL & INSTRUMENTATION

10.1 ROLE OF PROCESS INSTRUMENTATION AND CONTROL: The important feature common to all processes is that process is never in a state of static equilibrium for more than a very short period of time. A process is dynamic quantity subject to find to drive it away form the desired state of equilibrium the process must then be manipulated upon or corrected to drive it back towards the desired state and thus to maintain the efficiency of the process. Instruments are used to measure the variable such as temperature, pressure, composition, level, flow rate etc. In chemical industry it can be operated automatically, semi automatically or manually. Now a days must of the plant are controlled automatically by electronic controllers or by means of computer signals. Now days a DCS plant system is very popular in industry for controlling the various variables of operations. Plant with DCS system is highly sophisticated and more accurate result oriented. Instrument is applied to Acrylonitrile plant involves the use of level controls, flow rate controllers, temperature controller, pressure controller and automatic control of process variable. Electronic or pneumatic controller systems are used mostly. The automatic controller are much more efficient and accurate then manual controller because it is not possible all the time to controls the variable manually and hence it is necessary to fix the limit to give the optimum economic operation some of the operation equipment give alarm with light on the panel. The subsequent control is to be exercised when temperature, level, pressure, and flow deviates from its operating sate value. During the start up and shutdown of the plant and during abnormal and emergency conditions the plant is operated under manual control when plant becomes steady state and under normal operation it is operated under auto control. Automatic control is the norm throughout the chemical industry, and the resultant savings in labor combined with improved ease and efficiency of operations has more than offset the added expense of instrumentation. 103

All the operation in a chemical plant depends on the measurement and control of the process variables. Instruments are used in the chemical industry to measure process variables, such as temperature, pressure, density, viscosity, humidity, pH, liquid level, flow rate, chemical composition, specific heat, conductivity and dew point. By use of instruments having varying degrees of complexity, the values of these variables can be recorded continuously and controlled within narrow limits. 10.1.1 Instrumentation and Control Objectives: The primary objectives of the designer when specifying instrumentation & control schemes are, (a) Safe plant design: - To keep the process valuable within known safe operating limit. - To dictate dangerous situation as they develop in to provide alarms and automatic shut down systems. - To provide inter locks and alarms to prevent dangerous operating procedures. (b) Production rate: - To achieve the desired production output. (c) Production quantity: -To maintain the product consumption within the specified quality

standards.

(d) Cost: -To operate at the lower production cost, commensurate with the objectives. But sometimes it may be better strategy to product a better quality at a higher cost. (e) Labour: - The process can operate with less labour power and hence lower the operating cost. In a typical chemical processing plant, these objectives are achieved by a combination of control, manual monitoring & laboratory analysis. 10.2 PROCESS MEASUREMENT: Process measurements encompass the application of the principles of metrology to the process in question. The objective is to obtain values for the current conditions within the process and make this information available in a form usable by either the 104

control system or process operators, or any other entity that needs to know. Process measurements fall in two categories: 10.2.1 Continuous measurements: Most process control application in continuous processes rely on continuous measurements. The components of a typical continuous measurement device are sensor, transmitter and signal processor. The sensor produces a single that is related in a known manner to the process variable of interest. The single processor linearizes this relation and compensates for effect of other variables. The transmitter generates a signal that can be transmitted over some distance. 10.2.2 Discrete measurements: In batch processes, discrete measurements are more widely used. These measurements are also used in safety interlock for both continuous as well as batch processes. 10.3 TEMPERATURE CONTROL: Measurements of the hotness or coldness of a body or fluid is commonplace in the process industries. Temperature measuring devices utilize systems with properties that vary with temperature in a simple, reproducible manner. Temperature can be determined by measuring several physical properties as the specific volume of fluid, electrical resistivity of metal, thermoelectric potential at the junction of a pair of dissimilar metals, colour comparison or light wavelength. Table-10.1 Temperature ranges for certain instruments: Thermocouple

200oC to 1820oC

pyrometers

1300oC to 250oC

vapor pressure thermometer

85oC to 425oC

mercury in glass thermometers

27oC to 400oC

Bimetal thermometers

180oC to 580oC

Thermistors

upto + 300oC

Resistance thermometers

200oC to 850oC

105

10.4 PRESSURE CONTROL: Pressure control will be necessary for most systems handling vapor or gas, the method of control will depend on the nature of the process. Safety of chemical plants depends upon the timely measurement of pressure and its control at a specified level. Any excess pressure development than the design pressure may damage the equipment in addition to the fire and other explosion hazard. Pressure can be in absolute, gauge, vacuum or differential form. Process pressure measurement devices are divided into three groups: (A) Devices based on measurement of height of a liquid column. (B) Devices based on measurement of distortion of an elastic pressure chamber. (C) Electrical sensing devices. Monometers: (U-tube, Differential, Inclined) fall into first category. Bourdon tubes, bellows and diaphragm fall into second category. Strain gauges, piezoelectric transducers etc. fall into third category. 10.5 LEVEL CONTROL: In any equipment where are interface exists between two phases some means of maintaining the interface at the required level must be provided. The measurement of level can be defied as the determination of the location of the interface between two fluids, separable by gravity, with respect to a fixed datum plane. The most common level measurement is that of the interface between a liquid and gas. Other level measurements frequently encountered are the interface between two liquids, between a granular or fluidized solid and gas, and between a liquid and its vapor. Float actuated devices, head devices, electrical methods, sonic methods and thermal methods are used for level measurements. This may be incorporated in the designing of the equipment, as is usually done for decanters or storage tanks or by automatic control or the flow from the equipment. 10.6 FLOW CONTROL: Flow defined as volume per unit time at specified temperature and pressure conditions, is generally measured by positive displacement of rate meters. The principal classes of flow measuring instruments used in the process industries are 106

variable head, variable area, positive displacement and turbine instruments, mass flowmeter, vortex-shedding and ultrasonic flowmeters, magnetic flowmeters, and more recently, coriolis mass flowmeters. Orifice meter, venturimeter and pitot tube are the most common head flow meters and rotameter is an area flowmeter. In head flowmeter, area available for flow is variable which in area flowmeters, it is a constant quantity. Flow control is usually associated with inventory control in a storage tank or other equipment. There must be a reservoir to tank up the change in flow rate. To provide flow control on a compressor or pump running at a fixed and supplying a near constant volume out put a by pass control would be used. 10.7 ALARMS AND SAFETY TRIPS AND INTERLOCKS: Alarms are used to alert operations of serious and potentially hazardous deviations in process conditions. Key instruments are fitted with switches and relays to operate audible and visual alarms on the control panels and annuciator penels, where delay or lack to the rapid development of a hazardous situation, the instrument would be fitted with a trip system to take action automatically to prevent the hazard, such as shutting down pumps, closing valves, operating emergency systems. The basic compounds of the automatic trip system are : 1.

A sensor to monitor the control variable & provide an out put signal when a present valve is exceed the instrument.

2.

A link to transfer the signal to the actuator usually consisting a system of pneumatic or electric relays.

3.

An actuator to carry out the required action: close or open valve switch of a motor.

10.8

INSTRUMENTATION

AND

PROCESS

CONTROL

FOR

ACRYLONITRILE REACTOR: The reactor is a fluidized bed catalytic gas-solid reactor. The instrument s and controls provided over and around this reactor are discussed as follows. The feed to reactor is,

107

Air

= 2.2 kg/cm2 and 170oC

Propylene

= 2.5 kg/cm2 and 56oC

Ammonia

= 2.3 kg/cm2 and 65oC

Air is heated in start-up heater, the outlet temperature recorded by temperature recording controller (TRC-1) which control he Burner System used for heating purpose. Propylene and Ammonia is heated n super heater using steam. The steam flow rate is controlled by temperature recording controller (TRC-2 & 3). Air propylene and Ammonia flow rate as feed to reactor is controlled by flow recording controllers (FRC 4 and 5, 6). The flow rate of air is maintained by venting air to atmosphere by anti surge flow which is controlled by flow controller (FIC-7). The pressure of Propylene and Ammonia is controlled by pressure indicating controllers (PIC-8 & 9). The pressure of air outlet from air compressor is controller with pressure indicating controller (PIC-10) by regulating the speed of compressor. The temperature of Reactor is obtained on the temperature indicator and recorder (TR-11) from a thermocouple mounted on reactor shell. The pressure of reactor is indicated by pressure indicator and recorder (PR-12)at top of reactor. The reactions in reactor exothermic. So temperature of reactor changes as reaction proceeds. We must provide temperature indication controller (TIC-13) which controls the inside temperature of reactor by providing proper coolant flowrate into steam coils in the reactor to remove heat evolved during reaction.Level indicator (LR-14) indicates the level of fluidized bed in the reactor. 10.9 INSTRUMENTATION AND PROCESS CONTROL FOR OTHER EQUIPMENTS: 10.9.1Distillation Column Control:The primary objective of distillation column is to maintain the specified composition of the top & bottom products and side steams co-relating to the Effects of distillation in:

108

1) Feed flow rate, composition & temp. 2) Stream supply pressure. 3) Cooling water pressure & Heating temp. 4) Ambient conditions, which cause change in internal reflux. A variety of the control schemes are used to Distillation column control for continuous, versatile control of distillation column processes, the requirement generally adopted is the constant temp profile in the column. This ensures preservation of equilibrium between the liquid & vapour phase in the column. The relevant variables to maintain this profile is pressure, boil up rate, reflux ratio & reflux temp. Although composition control by direct analysis of the product streams is feasible. It is practiced due to the expenses of metering equipment of & because of the intolerable response lime for accurate control purpose. Product sample be analyzed by chromatographic or other techniques, however, as a periodic check on quality. Any change vapor flow rate upward through the column is due to variation in boil up rate will alter the press at the top of the column and this provides a basic for control of the boil up rate by regulation of reboiler steam pressure using a pressure controller. The reflux rate will be controlled using measurement of liquid level in the reflux drum to control total condensate flow and measurement of liquid level in the reflux drum to control total condensate flow and measurement and comparison of both distillate and reflux rates to ensure that the specified reflux ratio is maintained. Control of the reflux stream temperature will be achieved by the use of the temp. Controlled which actuates the cooling water inlet valve of the condenser.

109

CHAPTER-11: SAFETY & POLLUTION CONTROL

11.1 SAFETY AND POLLUTION CONTROL: Any organization has la legal and moral obligation to safe guard the health and welfare of its employees and the general public. Safety is also good business; the good management practice needs to ensure safe operation will also ensure efficient operation. All manufacturing processes are to some extent hazardous, but in chemical processes there are additional, special hazards associated with the chemical include toxicity, flammability, explosions, sources of ignition, pressure variations, temperature variations and noise. Toxic and corrosive chemicals, fires explosions and mechanical equipment are the major health and safety hazards encountered in the operation of plants in the process industries. Maximum protection must be provided to the plant personal and there must be a maximum chance of occurrence of accidents. 11.2 CHEMICAL HAZARDS:Many chemicals can cause dangerous burns if they come in contact with tissues. Dehydration by strong dehydrating, agents, digestion by strong acids and bases and oxidation by strong oxidizing agents can destroy living tissues. Eyes and the mucous membranes of the nose and throat are particularly susceptible to the effects of corrosive dusts, mists and gases. Tolerance levels of toxic chemicals and explosive limits for various flammable materials must be known. 11.3 FIRE AND EXPLOSION HAZARD:Careful plant layout and judicious choice of constructional material reduced the chance of this hazard. Hazardous operation should be designed to meet the specification and codes. Adequate venting is necessary and it is advisable to provide protection by using both spring loaded values and rupture disks. Possible sources of fire are reduced by eliminating all unnecessary ignition sources such as flames, sparks of heated, materials, matches, smoking, welding, cutting static

110

electricity spontaneous combustion and non explosion proof electrical equipment are all potential ignition sources. Fire alarms, temperature alarms, fire fighting equipment and sprinkler system must be available readily in the plant. First aid stations, protected walk ways and work areas should be provided in the final plant. 11.4 AIR AND LAND POLLUTION:Electrostatic precipitators, venturi scrubbers cyclones, sonic agglomerators, scrubbers, washers and many other kinds of equipment and treating methods should be used to remove atmospheric contaminants from waste gases. Incineration and burying in concrete encased blocks are possible solution for dangerous solid wastes. Transportation to uninhibited regions is solution form other types of solid waste. 11.4.1 Water Pollution:Dissolved inorganic slats, acid and alkalis suspended solids and floating matter, oxygen-consuming materials, other toxic materials taste and color producing materials etc. must be. 11.5 SAFETY IN PLANT: There are primarily two types of major hazards in petrochemical industry: a. The first is due to flammability low flash point and wide explosive limits of the chemicals handled and b. Toxic hazard due to toxicity and carcinogenicity of various chemicals. Complete understanding of the chemicals, their physical and chemical properties, especially with respect to reactivity, is very important for their safe handling. Mankind today is used great deal comfort which would have been beyond the imagination of our ancestors. Today petrochemicals are part and parcel of our daily lives. The contribution of petrochemicals to modern civilization is immense. We cannot imagine the chaos that would ensue if petrochemicals suddenly cease to exist. Hence, despite the hazards, we must continue to produce petrochemical. The industry has to expand, develop and operate continuously if the growth of civilization is continuing unabated. The primary objective in achieving the above goals is to tame

111

the hazards. For this it may be necessary to change the work situation, to choose designs and methods of working which eliminate or reduce these hazards. Concept of Inherently Safer Plants: 7KH FRQFHSW LQ WKH GHVLJQ SI SHWURFKHPLFDO SODQWV KDV VZLWFKHG IURP ³,QWULQVLFDOO\ 6DIH´WR³,QKHUHQWO\6DIHU´3ODQWVWKLVGRHVQRWPHDQWKDWWKHUH should be a ban on plants which handle hazardous materials or contain large inventories. It is merely suggested that we should: Consider the alternative processes while selecting the technology Innovate in the design of equipment which make s the operations simpler and less hazardous and Make low inventory one of our main aims. ,IZHDSSO\WKHDERYHFRQFHSWRI³,QKHUHQWO\6DIHU´SODQWVDWWKHYHU\EHJLQQLQJRID project, we may be able To choose a route that avoids the use of hazardous raw materials or intermediates To choose or develop equipment design which does not require larger quantities of materials in process. Alternative Route of Production: As in Acrylonitrile plant use Sohio Process which handle less quantity of HCN highly poisonous material compare to other manufacturing process as alternative technology. 11.6 CONCEPT OF SAFER DESIGNS: In the design of the equipment for hazardous petrochemical plants, it is possible to reduce the hazards by utilizing certain innovations which will reduce the inventory of hazardous chemicals. These are simple and help to achieve the required objective. Below are observations which will help in this direction:11.6.1 Reactor Design: A tubular reactor is safer than a pot reactor. For a 20,000 MTA plant, a 5 cm diameter tubular reactor is sufficient with 1 meter per second velocity. In IPCL, Baroda complex an 80,000 MTPA low density polyethylene plant has a tubular reactor size of 5 cm only. If the rupture disc blows up because of decomposition, the total volume released into the atmosphere is only about 300-600 kg which is easy to control 112

Vapor phase reactors may be developed to liquid phase reactors. Sometimes larger reactors are required because the conversion may be low or the mixing is poor. It may be possible to improve the conversion by changing the parameters or incorporating better methods of mixing. 11.6.2 Distillation Columns: Inventory in distillation columns can be reduced by: Incorporating a narrow base Internal calendrias. Combining two distillation stages in one. 11.6.3 Exchangers: Inventory of hazardous materials can be reduced: By putting more hazardous materials in tubes. Use of higher flow rates. Use of extended surface exchangers Higher temperature differences. 11.6.4 Storage in Safer Form: Hazardous chemical can be stored or used in less hazardous forms. Store materials in less hazardous form using coolant, inhibitor or other additives. Keep suitable environment to store materials. 11.6.5 Safer Designs: Overhead condensers and reflux by gravity and withdrawal of product etc. by gravity will reduce the pressure handling increase safety. Sometimes it may be possible to dispense with relief valves and all that comes after them by using strong vessels, strong enough to withstand the highest pressure that can be reached. Similarly instead of installing vacuum relief valves we can make vessels to withstand full vacuum.

11.7 PREVENTION AND CONTROL OF HAZARDS IN ACRYLONITRILE PLANT: Acrylonitrile is produced by ammoxidation of propylene in a fluidized bed reactor using bismuth molybdenum based catalyst. Hydrocyanic acid (Hydrogen cyanide) 113

and acetonitriel are the co products of ammoxidation of propylene. The extreme toxicity of hydrocyanic acid is well known. Added to this, the low boiling point and tendency f HCN to polymerize violently has led us to take extreme care in handling this hazardous chemical. Of late, Acrylonitrile, once considered a harmless chemical, is now being designated as carcinogenic. Safety Aspect at Design Stage: 11.7.1 Fire and explosion: (1) The reaction is vapor phase reaction, being an oxidation reaction. The reactor and its associated equipment are very prone to the hazard of explosion. Apart from normal operation, start-up and shutdown of the reactor are the most critical stages. Before start-up, the organic content downstream of reactor is checked in quench column, to avoid formation of explosive mixture when air is diverted. (2) The ratio of ammonia to air is fixed in such a way that effluent from the reactor contains oxygen much below the explosive limit of ammonia and oxygen. Only when oxygen content falls below seven percent is propylene added to the reactor. Cooling coils are taken not operation to control the reactor temperature. (3) All the safety valves from the column and propylene system are connected to a hydrocarbon flare which passes through a water seal drum is connected to a closed toxic sewer system. The safety valves are purged with nitrogen to avoid stagnancy of acrylonitrile/HCN, which on polymerization block the outlet. The flare is also provided with a molecular seal to eliminate the chance of flash back. 11.7.2 Environmental Hazard: (1) Acrylonitrile, hydrogen cyanide and acetonitriel present environmental hazards. Detailed engineering is done keeping in view the minimum leakages. All the pumps handling aqueous stream are provided with single mechanical seals and those handling organics are provided with double mechanical seals.

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The outlet of seals is connected to a closed toxic sewer which is reprocessed in the plant to recover the organics. (2) All the floor washing including the water from the plant area are collected in big pits each, and only after testing for cyanide, COD and pH are they sent to the effluent channel. If needed provision also exist for incinerating the storm water. (3) All the column blow downs from the plant are incinerated. The incinerator temperature is kept at 700-8000C to burn all the organics. (4) Acrylonitrile plant should have flare as stand by for hydrocyanic acid vapors. The HCN-rich gases are normally sent to the incinerator. In case of incinerator stoppage HCN is automatically diverted to flare. Flare tip is provided with temperature sensing and alarm in the control room to indicate whether pilot burner is on or not. (5) HCN purification section is kept running only when there is demand. A policy decision has been taken not to keep any inventory for HCN. (6) Fortunately HCN area is provided with water deluge system with two independent supply sources and can be operated from control room. The deluge system is placed in such a way as to cover the complete HCN area. (7) Separate low temperature system is installed to cool HCN to zero or subzero temperature. 11.7.3 Routine Checks: The safety systems provided for the plant are periodically checked for healthiness. (1) The reactor start-up and operation checklist includes the testing of safety systems connected with reactor. (2) The oxygen analyzer is calibrated twice a week (3) The environment air is sampled with draeger tube periodically to detect leaks. (4) The water deluge system is checked every week. (5) The safety valves are regularly checked for setting.

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11.7.4 Manpower Training and Structure: (1)

An important aspect in reducing the hazards in operation and handling in the petrochemical industry is educating the people involved and making them follow certain set procedures by incorporating certain checklists so that chances of human errors are further eliminated. Periodic training of the personnel and religious following of the checklists are part of the routine.

(2)

In each plant there should be a separate independent Safety Engineer to monitor and ensure that the safety procedures are strictly followed. The Safety Engineer reports to the Safety Department though he is selected from among t operating personnel.

(3)

Each plant should have a Safety Committee which will meet at least once in a quarter to identify the hazardous areas in both maintenance and operation. Suggestions for improving work situations should be discussed and considered. A list of such suggestions should be making, implemented and monitored by the Safety Engineer.

(4)

Periodical medical check-ups of the plant personnel should be carried out and recorded for monitoring.

11.7.5 Other Safety Measures: As operation of the plant continues many areas where enough attention was not given during the design stage will be revealed. These areas are then identified and necessary modifications carried out for improving safety. Some modifications which are being carried out in ACN Plant: (1) Low temperature storage with high temperature alarm in control room, for higher stability of chemicals and reduction of environmental pollution. (2) Arrangement for short stops as a secondary safety measure in case of failure of the above. (3) Scrubber on the vents to reduce pollution and exposure of operating personnel. (4) Extension of water sprays systems to cover more areas which absorb HCN on leakage.

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(5) Seal less pumps for reducing environmental pollution and for safety of operating personnel. 11.7.6 Conclusion: We realize and agree that petrochemicals are going to stay with us in various forms. We cannot discard them just because there are hazards encountered in their production and handling. We try to change out concept in the design of petrochemical plants from intrinsically safe to inherently safer plants. The following guidelines have been given by Kletz for controlling hazardous materials. a. Avoid them (substitution). b. Use less of them (intensification). c. Use them under conditions which make them less hazardous (attenuation). d. Contain them, so that they do not leak out. e. Control leaks ± by emergency isoration, open plants to encourage dispersion. f. Survive leaks ± by fire protection, fire fighting etc. In short there are three choices before us: 1. We can do without chemical plants and their products and the benefits and risks they bring to mankind but it would be a journey back in time. 2. We can try to work out the risks and play safe. But the situation will never be completely safe. 3. We can try to change the work situation, choose designs and methods of working which eliminate or reduce the hazards and proceed with the venture. 11.8 ACRYLONITRILE (CH2 = CHCN): 11.8.1 Characteristic: We discussed in chapter 1 about characteristics of acrylonitrile Odor: Colorless to pale yellow liquid with a pungent odor which can only be detected at concentrations above the permissible exposure level, in a range of 13-19 parts Acrylonitrile per million parts of air (13-19 ppm).

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11.8.3 Exposure may not exceed either: 1. Two parts Acrylonitrile per million parts of air (2 ppm) averaged over eight-hour workday; or 2. Ten parts Acrylonitrile per million parts of air (10 ppm) averaged over any 15minute period in the workday. 3. In addition, skin and eye contact with liquid Acrylonitrile is prohibited. 11.8.4 Symptoms: Dermatitis, lacrimation (flow of tears), headache, weakness, vomiting, diarrhea, jaundice, suffocation, fatal. 11.8.5 Health Hazard Data: (a) Acrylonitrile can affect your body if you inhale the vapor (breathing), if it comes in contact

with your eyes or skin, or if you swallow it. Acrylonitrile is highly toxic

if ingested. It is extremely irritating and corrosive to skin and eyes. It may enter your body through your skin. (b) Effects of Overexposure: 1) Short-Term Exposure: Acrylonitrile causes eye irritation, nausea, vomiting, headache, sneezing, weakness, and lightheadedness. At high concentrations, the effects of exposure may go on to loss of consciousness and death. When acrylonitrile is held in contact with the skin after being absorbed into shoe leather or clothing, it may produce blisters following several hours of no apparent effect. Unless the shoes or clothing are removed immediately and the area washed, blistering will occur. Usually there is no pain or inflammation associated with blister formation. 2) Long-Term Exposure: Acrylonitrile is categorized as a cancer hazard by OSHA. It has been determined to be carcinogenic to laboratory animals and mutagenic in both mammalian and non-mammalian tests. Genetic transformations and damage have been reported in tissue cultures exposed to acrylonitrile. Animal tests show that it is a reproductive toxicant only at maternally toxic doses. Repeated or prolonged exposure of the skin to acrylonitrile may produce irritation and dermatitis.

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Permissible exposure limits for acrylonitrile in the United State are 2 ppm for and 8-h time weighted average concentration and 10 ppm as the ceiling concentration for a 15 min period. 3) Reporting Signs and Symptoms: You should inform your employer if you develop any signs or symptoms which may be caused by exposure to acrylonitrile. 11.8.6 Emergency First-aid Procedures: (1) Eye Exposure: If acrylonitrile gets into your eyes, wash your eyes immediately with large amounts of water, lifting the lower and upper lids occasionally. Get medical attention immediately. Contact lenses should not be worn when working with this chemical. (2) Skin Exposure: If acrylonitrile gets on your skin, immediately wash the contaminated skin with water. If acrylonitrile soaks through your clothing, especially your shoes, remove the clothing immediately and wash the skin with water. If symptoms occur after washing, get medical attention immediately. Thoroughly wash the clothing before re-using. Contaminated leather shoes or other leather articles should be discarded. (3) Inhalation: If you or any other person breathes in large amounts of acrylonitrile, move the exposed person to fresh air at once. If breathing has stopped, perform artificial respiration. Keep the affected person warm and at rest. Get medical attention as soon as possible. (4) Swallowing: When acrylonitrile has been swallowed, give the person large quantities of water immediately. After the water has been swallowed, try to get the person to vomit by having him touch the back of his throat with his finger. Do not make an unconscious person vomit. Get medical attention immediately. (5) Rescue: Move the affected person from the hazardous exposure. If the exposed person has been overcome, notify someone else and put into effect the established emergency procedures. Do not become a casualty yourself. Understand your emergency rescue procedures and know the locations of the emergency equipment before the need arises.

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(6) Special First-Aid Procedures: First-aid kits containing an adequate supply (at least two dozen) of amyl nitrite pearls (impulse), each containing 0.3 ml, should be maintained at each site where acrylonitrile is used. When a person is suspected of receiving an overexposure to acrylonitrile, immediately remove that person from the contaminated area using established rescue procedures. Contaminated clothing must be removed and the acrylonitrile washed from the skin immediately. Artificial respiration should be started at once if breathing has stopped. If the person is unconscious, amyl nitrite may be used as an antidote by a properly-trained individual in accordance with established emergency procedures. Medical aid should be obtained immediately. 11.8.7 Emergence Treatment and Measures: (1) Hygienic Precautions: Adequate ventilation. No food and smoking in working area. Preclude from exposure those individuals with pulmonary and lever diseases. (2) Hygienic Treatments (First Aid): Remove immediately the exposed personnel from the contaminated area. Wash promptly the skin with abundant soap and water. Irrigate eyes completely with water. Administer artificial respiration followed by inhalation f amyl nitrile every 5 minutes. Treat the patient with 10 cc of 3% sodium nitrile dose intramuscularly within 2 minutes followed by administration of 50 cc of 25% sodium thiosulfate in the same way. Hospitalize. Treat accidental swallowing by inducing vomiting orally using 1% sodium thiosulfate followed by injecting 50cc of 25% sodium thiosulfate intravenously. 11.8.8 Fire Hazards: It is highly ignitable and flammables. Its ignition point of water solution are (2%) 211 o

C, (3%) 12 oC, (5%) below 9 oC. It is polymerized violently in presence of

concentrated alkalis. Extreme care is needed if it is treated with strong alkali. Acrylonitrile tends to polymerize even at room temperature by light, gives high heat and a container may rupture on polymerization.

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Fire extinguishments: Fight a fire a safe distance. i) 8VHH[WLQJXLVKHUVRIGU\FKHPLFDO³DOFRKRO´IUDPRU carbon dioxide. ii) Shut off source of supply. iii) Use dry chemical, CO2 or foam. iv) Water may be ineffective, but useful to cool fire-exposed containers. Keep surrounding area cool under water fog.

11.8.9 Respirators and Protective Clothing: (1) Respirators: You may be required to wear a respirator for non-routine activities, in emergencies, and while your employer is in the process of reducing acrylonitrile exposures through engineering controls. If respirators are worn, they must have a label issued by the National Institute for Occupational Safety and Health (NIOSH) under the provisions of 42 CFR part 84 stating that the respirators have been approved for use with organic vapors. For effective protection, respirators must fit your face and head snugly. Respirators should not be loosened or removed in work situations where their use is required. Acrylonitrile does not have a detectable odor except at levels above the permissible exposure limit. Do not depend on odor to warn you when a respirator cartridge or canister is exhausted. Cartridges or canisters must be changed daily. Reuse of these may allow acrylonitrile to gradually filter through the cartridge and cause exposures which you cannot detect by odor. If you can smell acrylonitrile while wearing a respirator, the respirator is not working correctly. Go immediately to fresh air. If you experience difficulty breathing while wearing a respirator, tell your safety officer. (2) Supplied Air Suits: In some work situations, the wearing of supplied-air suits may be necessary. Your employer should instruct you in their proper use and operation. (3) Protective Clothing: You must wear impervious clothing, gloves, face shield, or other appropriate protective clothing to prevent skin contact with liquid acrylonitrile. Where protective clothing is required, your employer is required to provide clean garments to you as necessary to assure that the clothing protects you adequately. Replace or repair impervious clothing that has developed leaks. Acrylonitrile should never be allowed to remain on the skin. Clothing and shoes which are not impervious 121

to acrylonitrile should not be allowed to be contaminated with acrylonitrile, and if they do, the clothing and shoes should be promptly removed and decontaminated. The clothing should be laundered or discarded after the acrylonitrile is removed. Once acrylonitrile penetrates shoe leather, or other leather articles, the article should not be worn again. (4) Eye Protection: You must wear splash-proof safety goggles or face shields in areas where liquid acrylonitrile may contact your eyes. In addition contact lenses should not be worn when working with acrylonitrile. 11.8.10 Precautions for Safe Use, Handling, and Storage: (1) Temperature: Acrylonitrile is a flammable liquid and its vapors can easily form explosive mixtures in air. Safe storage temperature is 25oC. Do not store uninhibited Acrylonitrile. It is not stable unless stabilizer is added (i.e. Aqua ammonia or MEHQ). It polymerizes fast with exothermic reaction. (2) Container: Acrylonitrile must be stored in tightly-closed containers in a cool, well-ventilated area, away from heat, sparks, flames, strong oxidizers (especially bromine), strong bases, copper, copper alloys, ammonia, and amines. Protect containers against physical damage. Store drum on end with bungs up, no more than two layers. Preferably seal with inert gas such as nitrogen. (3) Fire protection: Sources of ignition such as smoking and open flames are prohibited wherever acrylonitrile is handled, used, or stored in a manner that could create a potential fire or explosion hazard. You should use non-sparking tools when opening or closing metal containers of acrylonitrile, and containers must be bonded and grounded when pouring or transferring liquid acrylonitrile. Fire extinguishers and quick drenching facilities must be readily available, and you should know where they are and how to operate them. (4) Body protection: You must immediately remove any non-impervious clothing that becomes contaminated with acrylonitrile, and this clothing must not be rewash until the acrylonitrile is removed from the clothing. Impervious clothing wet with

122

liquid acrylonitrile can be easily ignited. This clothing must be washed down with water before you remove it. If your skin becomes wet with liquid acrylonitrile; you must promptly and thoroughly wash or shower with soap or mild detergent to remove any acrylonitrile from your skin. If you handle acrylonitrile, you must wash your hands thoroughly with soap or mild detergent and water before eating, smoking, or using toilet facilities. You must not keep food, beverages, or smoking materials nor are you permitted to eat or smoke in regulated areas where acrylonitrile concentrations are above the permissible exposure limits. Ask your supervisor where acrylonitrile is used in your work area and for any additional plant safety and health rules. (5) Spills and Leakage: (a) Absorb with papers. Allow to evaporate on a glass or iron dish in a hood. Dispose by burning the paper. (b) Add excessive sodium hydroxide and calcium hypochlorite solution on. Transfer into a large beaker. After one hour, drain in to the sewer with sufficient water and wash the split site. (6) Disposal and Waste Treatment: Add by stirring excessive alcohol sodium hydroxide. After one hour, evaporate alcohol and add sufficient calcium hypochlorite. After 24 hours drain into the sewer with abundant water. 11.9 ACETONITRILE: Safety data sheet (A)Characteristics: 1)

Flash point

: 55oC

2)

Auto ignition temperature

: Not Known

3)

Flammable limits

: Lower ± 4.4%, Upper ± 16%

4)

TVL

: 40 ppm

(B) Health Hazards: Highly toxic when ingested and can be absorbed through skin and respiratory tract. Inhalation cause headache, nausea, loss of consciousness or dizziness. 123

(C) Fire Hazard: Dangerous when exposed to heat or flame. When heated to decomposition it emits highly toxic fumes of cyanides and react with water steam r acids to produces toxic flammable vapors. (D) Safe Handling: Keep away from heat and flame. Use self contained breathing apparatus. War full protective clothing. (E) Fire extinguishments: Use dry FKHPLFDO µ$OFRKRO IRDP¶ RU &22 extinguisher. Wear special protective clothing. (F) First Aid: Remove the patient to the fresh air. In case of skin contact, wash with plenty of water. In all cases report to Medical Center. 11.10 HYDROGEN CYANIDE: (A) Characteristics: 1) Flash point

: 0oc

2) Auto ignition temperature

: 535.7oc

3) Flammable limits

: Lower ± 6%, Upper ± 41%

4) TLV

: 10 ppm

(B) Health Hazard: HCN is one of the most lethal chemical of cyanide group. When HCN is inhaled or ingested Cyanide group is liberated which combines with hemoglobin in blood and reduces the capacity of blood to transport oxygen and causes death. Following special provisions must be kept to handle HCN safely. 1) HCN leak emergency siren is provided. Regular testing of this system is done once in a week. 2) Water spray deluge system is provided at various locations in the plant. 3) On line HCN leak monitoring system is provided at various points in piping carrying HCN. 4) The ventilate above HCN incinerator should be high enough. 124

5) In HCN section all lines are sloping so that no HCN accumulates in pipe lines. 6) All control valves in HCN section are below seal type so that no leakage from its gland/steam is possible. 11.11 AMMONIA: (A)Flammability: : 651oC

Ignition temperature Explosive limits

NH3 ± O2 mixture (at 20oC, 101.3 KPa) = 15.79 Vol % NH3 NH3 ± Air mixture At 0oC, 101.3 KPa) o

At 100 C, 101.3 KPa)

= 16 -27 Vol % NH3 = 15.5 ± 28 Vol % NH3

The presence of oil of other combustible materials will increase the fire hazards. Readily combines with either silver oxide or mercury to form explosive compounds. Toxicity:-

TLV ± 50 ppm

TDL: Inhalation ± human (ihl ± hmn) LCL: 1000 ppm/3h ihl ± hmn TCL : 20 ppm TFX : Irritation ihl ± hmn TCL : 1000 mg/kg TFX : Carcinogenic (B) Heath hazards: Symptoms: Affects sensitive membranes of the eyes, nose, throat and lungs depending on concentration. Because of its great attractively to water, it is particularly irritating to moist skin surfaces. Liquid ammonia may cause severe injury by freezing the tissues and subjecting it to caustic action. Inhalation in high concentration may cause edema of respiratory tract, fit of the glottis and suffocation. Highly irritant and erosive to skin and mucous membranes which may affect deeply into the tissues. Visual disorder may occur by contact to the eyes. It may cause headache, vomiting, cough and difficulty in breathing. (C) Handling and Storage: Ammonia is stored in liquid state by two methods 125

1.

Pressure storage at ambient temperature in spherical or cylindrical pressure vessel Atmospheric storage at 33oC in insulating cylindrical tanks.

2.

Outdoors or detached storage is preferred. Indoor storage should be in a cool, will ventilated, non combustible location, away from all possible sources of ignition and separate from other chemicals particularly oxidizing gas, chlorine, bromine, iodine and acids. Cylinders should be protected from direct sunlight and all possible precessions. Hazardous reaction with: Substance

Condition

Reaction

Remarks

Halogens

Contact

Explosion

Halogenated Nitrogen formed.

Chlorated

Formulates Explosion Ammonium chlorate is liable to explosion.

Wear face shied, chemical cartridge, respirator, rubber gloves and boots. (D) Emergency Treatment and Measures:(A)Hygienic precaution: preclude from exposure for those individuals affected with eye and pulmonary diseases. (B)Hygienic Treatments (First Aid): Irritate eyes with water and instill droplets of olive oil. Forcible removal of frozen clothing may tear the skin badly hence proper precaution must be taken while undressing. Wash contaminated area of body with soap and water. Oxygen should be taken up with sue of intermitted positive pressure breathing apparatus. (C)Fire precautions: Use water to keep fire exposed container cool and also to protect the men affected. Spills and leakage: Neutralize with HCl, wipe mop or use, water aspirator. Drain into a sewer with sufficient water. Disposal and waste Treatment: Pot into large vessel containing water and neutralize with HCl. Discharge into a sewer with sufficient water. 11.12 GENERAL SAFETY ASPECTS IN CHEMICAL PLANT: How to handle Chemicals: Be serious! «DQGEHFDUHIXODURXQGFKHPLFDOVDWDOOWLPHV 126

Presently, the techniques used for the treatment of such a hazardous waste are either Incineration or Extensive chemical Treatment. Both of these methods are very costly and hence, an alternative economical method has been suggested in this paper. Initially, the pretreatment of hazardous waste should be done by hot alkali digestion and chemical coagulation so the COD/BOD and ACN contents could be reduced considerably. Such a pretreated waste effluent stream should then, be treated biologically. This treatment consists of two stages biologically. This treatment consists of two stage biological extended aeration system, where in bio-oxidation takes place. Approximately 85 to 90% reduction in COD and Cyanide level is achieved. By treating toxic cyanide waste by this method, considerable reduction in operating cost is expected. Thus, as could be observed from the above data, this stream contains high concentration of organic cyanides along with high COD/BOD value. Treatments: The following treatment can reduce COD/BOD and Acrylonitrile to considerable extent. (A) Physico-chemical treatment: i) Hot alkaly digestion ii) Chemical coagulation Hot alkaly digestion with 2 to 4% NaOH at the temperature of 100 to 110 oC for 1 to 3 hrs. Followed by cooling and chemical coagulation by Alum/lime and removal of sediments reduces CN and COD/BOD to large extent as could be observed from the following date: Table-11.1 COD/BOD table pH

8 to10

COD

20000 to10000 ppm

BOD

10000 to 20000 ppm

Organic Cyanides

10 to 30ppm

Colour

Light Brown

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To get rid of this pretreated effluent generally incinerated which require huge quantity of fuel or extensive chemical treatment is the only process. However the cost of incineration or chemical treatment is quite high, hence and alternative economical method is necessary. (B) Activated Sludge biological Process: Toxic cyanide containing effluent can be treated biologically by two sludge activated sludge process under specific conditions. A schematic flow sheet for two stage biological treatment is shown in figure. Effluent water is collected in collecting chamber, in this for dilution purpose and to provide minerals and salts to biomass raw water or sanitary waste is added. In equalization pond it is aerated to equalize the mass as well as to remove volatiles. In

the next

step

pH

adjustment/coagulation

is

carried

out

by adding

Alum/lime/polyelectrolyte or any other coagulating agents/aids. Settled sludge is removed through clari floculator and supernatant is fed to 1st stage bioreactor with constant rate along with required dose of nutrients. Organic matters in the waste water gets decomposed by bio oxidation by aeration in the bio-reactor and mixed liquor is sent t clarifier from where with controlled rate activated sludg3is recycled back to the system and some portion is sent to sludge thickener and thickened sludge after centrifuging is discarded as cake. Supernatant from clarifier is retreated biologically in the second stage to have reduction of COD/BOD and CN up to 80 ± 95%. Feed

: maximum ACN level 15 ppm max (To be controlled by dilution)

COD

: 6000 ppm max

Ph

: neutral to alkaline up to 9 pH

Mixed liquor

: 3000 to 4000 ppm Suspended Solids

F/M

: 0.2 to 1.6

O2 supply

: 1.5 to 2.5 kg. O2/kg. COD Removed

Retention time

: 24 hour to 96 hour

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The above mentioned biological system is of standard norms, however since strong cyanide decomposing bacteria are of absolute different nature, the initial propagation and acclimatization is very much an art and considerably different from normal treatment. Required conditions during treatment. It must be noted that as ACN has strong toxic property, loading of the system should be with controlled rate. In order to reduce the influence of toxicity of ACN to biomass, effluent should be diluted initially by either raw water or sanitary waste t bring down the level of ACN and COD less than 15 ppm and 6000 ppm respectively. Also for healthy state of microorganisms 1 to 1.5% of P source and small amount of nutrients are added based on the BOD loadings. Thus as per the flow sheet digamma the effluent cyanide waste stream first under foes physico-chemical treatment where COD/BOD is diluted by digestion and coagulation. This is further diluted by sanitary and other waste water and as a result of biooxidation and biodegrading sludge is obtained out of bioreactors, 1 and 2. This sludge is filtered out and the clear liquid is obtained out of the clarifier. Conclusion: The process is not substantially different than that of standard activated sludge process, but separation of strong ACN decomposing bacteria, their propagation, cultivation and acclimatization is an art of this process. However it can be concluded that with special precautions, waste water containing toxic cyanide and extended aeration activated sludge biological treatment which reduces COD/BOD and ACN upto 90-95%. The initial investment may be high by 30 to 40 % more compared to the chemical process, but operating cost is quite low and operating cost difference pays off capital investment within about two to three years of time.

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CHAPTER-12: PLANT LOCATION AND LAYOUT

12.1 SELECTION OF PLANT LOCATION: The geographical location of the final plant layout can have a strong influence on the success of an industrial venture. Much care must be taken in choosing the plant site and many different factors must be considered. Primarily the plant should be located where the minimum cost of production and distribution can be obtained but other factors such as room for expansion and general living condition are also important. An appropriate idea as living reaches the detailed estimate stage and a firm location should be established upon completion of the detailed estimate design. The choice of the final site should be first based on a complete survey of the advantage and disadvantage of available real estate. The following factors should be considered in choosing a plant site. 12.2 PRIMARY FACTOR FOR PLANT LOCATION: 12.2.1 Raw Material availability: The source of raw material is one of the most important factors influencing the selection of plant layout. This is particularly true if large volumes of raw materials are consumed because location near the raw material sure permits considerable reduction in transportation and storage charge. Attention should be given to the purchase price of the raw materials, distance from the source of supply, freight or transportation expenses, availability and reliability of supply, purity of raw material and storage requirement. It is necessary that raw materials should be available in required quality and quantity without delay. For acrylonitrile, the raw materials are propylene available nearby petroleum refinery, ammonia available nearby fertilizer plant. 12.2.2 Markets: The location of market or intermediate distribution centers affects the cost of product distribution and the time required for shipping. Proximity to the large major markets is an important factor in the selection of a plant layout because purchasers usually find it advantageous to purchase from nearby source. 137

It should be noted that markets are needed for by products as well as for major final product. So, it is beneficial to have a chemical market near to the plant. 12.2.3 Energy Availability: Power and steam requirements are high in most industrial plants and fuel is ordinarily required to supply these utilities. Consequently power and fuel can be combined as one major factor in the choice of plant layout. The local cost of power can help determine whether power should be purchased or self generated for economic operation. 12.2.4 Climate: Weather has a seasonal effect on the economic operation of the plant. The temperature and humidity should be favorable. It should not be in the region where have more chances of Hurricanes, torpedo earth quake, Heavy flood and high wind velocity. Temperature range should be 15-40oC. If the plant is located in cold climate, costs may be increased by necessity for construction of protection shelters around the process equipment, and special cooling towers or air conditioning equipment may be required if the prevailing temperature are high. Excess humidity or extreme of hot or cold weather can have a serious effect on the economic operation of a plant and these factors should be examined when selecting a plant layout. 12.2.5 Water Supply: The process industry use large quantities of water for cooling, washing, steam generation etc. The plant, therefore, must be located where a dependable supply of water is available. A large river or lake is preferable although deep well or artisans well may be satisfactory if the amount of water required is not too large. The level of the existing water table can be checked by consulting the state geological survey and information on the constancy of the water table and the year round capacity of local river or lake should be obtained.

138

If the water supply shows seasonal fluctuation, it may desirable to construct a reservoir or to drill several stand by wells. The temperature, mineral content, salt or sand contents, bacteriological treatment must also be considered. Also potable water for staff must be easily available. 12.3 SPECIFIC FACTORS FOR PLANT LOCATION: 12.3.1 Transportation Facilities: A plant should have easy access to transport facilities. The transport facilities available to the plant must not be only easily accessible, but they must also be enough, quick and available at reasonable rates. Water, Rail, Roads and Highways are the common means of transportation. These facilities are very necessary for the transfer of raw materials and product transportation. Water, railroads, and highways are the common means for transportation used by industrial concerns. The kind and amount of product and raw materials determines the most suitable type of transportation to local freight rates and existing rail road lines. The proximity to railroad centers and the possibility of canal, river, lake or ocean transport must be considered. Motor trucking facilities are widely used and can serve as a useful supplement to rail and water facilities. If possible, the plant layout should have access to all three types of transportation and certainly atleast two types should be available. There is usually need for convenient air and rail transportation between the plant and the main company headquarters and effective transportation facilities for the plant personnel are necessary. 12.3.2 Skilled Labour Supply: Availability of skilled a labour and constant supply should be considered. The type and supply of labour available in the vicinity of a proposed plant layout must be examined. Consideration should be given to prevailing pay rated, restrictions on number of hours worked performance week, competing industries that can case dissatisfaction or high turnover rates among the workers, raid problems and variations in the skill and intelligence of the workers. Now a day, labour unions are the main look out of better site selection. Labour problems should be minimum.

139

12.3.3 Waste Disposal: The site should be such that it should have the best and adequate facilities for the waste which is coming out. In recent years many legal restrictions have been placed on the methods for disposing of waste materials from the process industries. The layout selected for a plant should have adequate capacity and facility for correct waste disposal. Even though a given area has minimal restrictions on pollution, it should not be assumed that these conditions will continue to exist. In choosing plant layout, the permissible tolerance levels for various methods of waste disposal should be considered carefully and attentions should be given to potential requirements for additional waste treatment facilities. 12.3.4 Tax and Legal Restrictions: State and the local tax rates on property, income, unemployment, insurance and similar items vary from one location to another. Some incentives are given by state or central government to particular industry likewise less tax rate or tax free zone in backward (Tribe) area, octori free for particular time period and subsidy, loan is also given. All these benefit reduces capital investment, production prices. So preference should be given to place where this type of facilities are available Similar local regulation on zoning, building aspects and transportation facilities can have a major influence on the final choice of a plant layout. In fact zoning difficulties and obtaining the required permits can often be much more important in terms of cost and time delay than many of the factors discussed in the preceding section. 12.3.5 Site Characteristic: The characteristics of the land at a proposed plant site should be examined carefully. The topography of the tract of land and soil structure must be considered. Since either or both may have a pronounced effect on construction cost and living conditions further changes facilities. Therefore even though no immediate expansions have been planned; new plant should be constructed at location where additional space is available.

140

12.3.6 Flood and Fire Protection: Many industrial plants are located along rivers of near bodies of water and there are risks of floods or hurricanes damage. Before choosing a plant layout the regional history of natural events of these types should be examined and consequences of such occurrences considered. Protection from losses by fire is another important factor in selecting plant location. The site should be such that it should have the best possible fire facility. If should located such that the fire station are nearer and adequate facilities are possible during the emergency. In case of a major fire, assistance form outside fire departments should be available. Fire hazards in the immediate area surrounding the plant layout not are over looked. 12.3.7 Advance Library and Training Center: To develop, the plant properly, trained staff is very much necessary and for further research advanced library facilities covering the subjects in detail, is necessary. 12.3.8 Community Factors: The gates are so placed that the material in and out of plant is systematically recorded and controlled. Provisions of probable future expansion is also taken into consideration and space provided for. The control room and laboratory are attached to plant so as to easy assess to plants. Attached laboratory allows prompt sampling, analyzing and reporting to control room of various changes and trouble shooting. Large cities offer the advantages of factory warehouse facilities so that replacement, parts of the plant can be readily obtained. The workers prefer to sue public transportation then such public transportation must be efficient ad economical. 12.4 PLANT LAYOUT: Once the location of the factory is decided handle the major equipments are at hand, the immediate step is to have specific plant layout. Layout of a plant in the factory means the allocation f apace, arrangement of equipment and machinery in such a manner that maximum utilization of men, machine and materials is done and

141

CHAPTER-13: COST ESTIMATION

A plant design obviously must present a process that is capable of operating under condition, which will yield a profit. Since net profit equals total income minus all expenses, it is essential that chemical engineer be aware of the many different types of costs involved in manufacturing processes. Money must be paid out for direct plant expenses, such as those for raw materials, labors and equipments. In addition many other indirect expenses are included, and these must be included if a complete analysis of the total cost is to be obtained. Some examples of these indirect expenses are administrative salaries, product distribution costs, and cost for inter plant communications. A capital investment is required for any industrial process; the determination of the necessary investment is an important part of a plant design project. Total investment for any process consists of the fixed capital investment for the physical equipment and facilities in the plus the working capital for money which must be available to pay salaries, keep law materials and product on hand, and handle other special items requiring a direct cash outlay. Thus, in an analysis of costs in industrial processes, Capital investment costs, manufacturing costs, and general expenses including income takes must be taken into consideration. The detail cost estimation is obviously very much essential for any project to estimate its profitability and hence feasibility. 13.1 FACTORS AFFECTING INVESTMENT AND PRODUCTION COSTS: 1.

Sources of equipment: - One of the major costs involved in any chemical

process is for the equipment. Standard available equipments are cheaper than specially design ones. 1) Price fluctuations: - In current scenario, the prices are very quite widely from period to another hence chemical engineer should consider this point while estimating the cost. 2) Company policies: - Policies of Individuals Company have a direct effect on costs. 144

3) Operating time and rate of production: -One of the factors that has important effect on costs is the variation of the total available time during which the process is in operation. 4) Governmental policies: - The national government has many regulations and restrictions, which have a direct effect on industrial costs. 13.2 CAPITAL INVESTMENT:Fixed ± Capital investments: Fixed Capital investment represent the capital necessary, for the installed process equipment with all auxiliaries that are needed for complete process design. Working capital: The working capital for an industrial plant consist of the total amount of money invested in, 1. Raw materials and supplies carried in stock 2. Finished products in stock and semi finished products in the process of being manufactured 3. Account receivable 4. Cash kept on hand for monthly payment of operating expenses, such as salaries, wages and raw material purchases 5. Accounts payable and 6. Taxes Payable. 13.3 ESTIMATION OF TOTAL PRODUCT COST:The total product cost intern is generally divided into the categories of manufacturing cost and general expenses. Manufacturing costs are also known as operating or production costs. Manufacturing costs: All expenses directly connected with the manufacturing operation or physical equipment of a process plant itself are included in the manufacturing costs. These expenses are divided into three classifications as follows: 1)Direct production costs 2) Fixed charges, and 3) Plant overhead costs.

145

General expenses: general expenses are classified as 1) Administrative expenses 1. Distribution and marketing expenses. 2. Research and development expenses. 3. Financial expenses 4. Gross earning expenses. 13.4 BREAKDOWN OF FIXED CAPITAL INVESTMENT ITEMS FOR A CHEMICAL PROCESS. 13.4.1 Direct costs 1. Purchased equipment All equipment listed on a complete flow sheet, spare parts and non installed equipment, supplies and equipment allowance, inflation cost allowance, freight charges, taxes, insurance, duties, and allowance for modification during startup. 1. Purchased-equipment installation, structural supports, insulation, paints. 2. Instrumentation and controls, purchase, installation, calibration 3. Piping: Process building-carbon steel, alloy, cast iron, lead, lined, aluminum, copper, asbestos-cement, ceramic, plastic, rubber, reinforced concrete. Piping hangers, fittings, valves insulation-piping equipment. 4. Electrical equipment and materials: Electrical equipment-switches, motors, conduit, wire, fittings, feeders, grounding, instrument and control wiring, lighting, panels. 5. Buildings (including services):Process building-substructures, superstructures, platforms, supports, stairways, ladders, access ways, cranes, monorails, hoists, elevators, auxiliary building-administration and office, medial or dispensary, cafeteria, garage, product warehouse, parts warehouse, guard and safety, fire station, change house, personal building, shipping office and platform, research laboratory, control laboratory. Maintenance shops-electric, piping, sheet metal, machine, welding, carpentry, instrument.

146

Building services-plumbing, heating, ventilation, dust collection, air condition systems, painting, sprinkler systems, fire alarm. 6. Yard improvements: Site development-site clearing, grading, roads, walkways, railroads, fences, parking areas, wharves and piers, recreational facilities, landscaping. 7. Utilities: Steam, water, power, refrigeration, compressed air, fuel, waste disposal. Facilities-boiler plant incinerator, wells, river intake, water treatment, cooling towers, water storage, electric substation, refrigeration plant, air plant, fuel storage, waste disposal plant, fire protection, non process equipment, shop equipment, automotive equipment, yard material-handling equipment, laboratory equipment, locker-room equipment, large equipment, shelves, bin, pallets, hand trucks, housekeeping equipment, fire extinguishers, hoses, fire engines, loading stations. Distribution and packing-raw-material and product storage and handling equipment, product packaging equipment, blending facilities, loading stations 8. Land Surveys and fees, property cost 13.4.2 Indirect costs 1) Engineering and supervision Engineering costs-administrative, process, design and general engineering, drafting, cost engineering, procuring, expediting, reproduction, communications, scale models, consultant fees, travel, engineering supervision and inspection. 2) Construction expenses Construction, operation and maintenance of temporary facilities, offices, roads, parking lots, electrical, piping, communications, fencing Construction tools and equipment Construction supervision, accounting, timekeeping, purchasing, expending Warehouse personnel and expense, guards Safety, medical, fringe benefits Permits,

147

field tests, special licensesTaxes, insurance, interest 3) CoQWUDFWRU¶VIHH 4) Contingency. 13.5 COSTING OF THE PLANT: 13.5.1 Fixed Capital Investment (A) Direct costs: (1) Purchase equipment cost (PEC) Table-13.1 PEC Sr.

Equipment

No.

Nos. of

Cost

Total cost

Units

Rs/unit

Rs.

1.

Ammonia storage tank

1

250000

250000

2.

Propylene storage tank

1

266000

26000

3.

Product storage tanks for HCN,

3

339400

1018200

ACN & AN 4.

Fluidized bet reactor

1

4791000

4791000

5.

Quencher

1

276800

276800

6.

Absorber

1

280000

280000

7.

Recovery column

1

610000

610000

8.

Distillation column

4

332750

1331000

9.

Electrical heater

3

85450

256350

10. Rotary compressor

2

366000

732000

11. Centrifugal pump

30

16000

480000

12. Reciprocating pump

8

36000

732000

13. Heat exchanger

12

246100

2954000

14. Cooler

4

133100

532400

15. Condensers

4

219600

878400

16. Reboiler (Kettle type)

4

166000

664000

17. Centrifugal separtor

1

104000

104000

18. Electrical heater

1

58500

58500

148

19. Cooling tower

2

166000

332000

20. Refrigeration unit

1

618000

618000

Total

17164650

13.5.1(A) Direct Cost 1. Purchased equipment cost (PCE)

= Rs. 17164650

2. Purchased equipment installation cost (0.5 PEC)

= Rs. 8582325

3. Instrumentation and control cost (0.2 PEC)

= Rs. 3432930

4. Insulation and painting cost (0.15 PEC)

=Rs. 2574697

5. Electrical installation (0.2 PEC)

= Rs. 3432930

6. Building cost (0.2 PEC)

= Rs. 3432930

7. Service Facilities (0.1 PEC)

= Rs. 1716465

Total direct cost (TDC) (A)

VXPPDWLRQµ¶WRµ¶

= Rs. 40339628

13.5.1(B) Indirect cost: 1. Engineering and supervision (0.5 TDC)

= Rs. 20168464

2. Construction and contractors fees (0.7 TDC)

= Rs. 2823850

3. Contingencies cost (0.5 TDC)

= Rs. 20168464

TIC = (B) = (1) + (2) + (3) = Rs. 6857277 Fixed capital investment (FCI)

= TDC + TIC = Rs. 108909706

Working capital investment WCI = 0.3 FCI

= Rs. 32672912

So Total capital investment TCI = FCI + WCI

= Rs. 141582618

13.5.1.C

Estimation of total product cost:

Manufacturing cost (A) Direct production cost (a) Raw material cost Basis = 330 working days

149

Table-13.2 Direct Production cost Sr

Raw Material

No.

Qty./year

Rate

Amounts

(Kg.)

Rs. kg

Rs.

1.

C3 ±cut

70 x 106

20

1400 x 106

2.

Ammonia

30 x 106

10

300 x 106

3.

Catalyst

5000

1000

5 x 106 1705 x 106

Total

(b) Labor and production supervision Table-13.3 Labor and production supervision Sr. Designation

Number

Rs./month

No.

Total Rs. Year

1.

M.D.

1

200000

2400000

2.

V.P.

5

150000

9000000

3.

G.M.

8

75000

7200000

4.

Process plant (i) Production manager

1

30000

360000

(ii) Chief Engineer

5

27800

1668000

(iii) Jr. Engineer

10

12000

1440000

(iv) Operator

15

6000

1080000

(v) Skilled Workers

10

3000

360000

(vi) Unskilled Workers

10

1500

180000

3

4000

144000

Supervisor

3

4000

144000

Workers

12

1500

216000

3

12000

432000

5.

Lab. Section Chemical

6.

7.

Utility Section

Maintenance Section Engg. (Mec.)

150

8.

9.

Engg. (Elec.)

3

12000

432000

Technicians

9

3500

378000

Officer

1

15000

18000

Clerical staff

5

5000

300000

Head

1

6000

72000

Security officer

1

3000

36000

Watchman

4

2000

96000

Heat

1

15000

18000

Officer

1

8000

96000

Others

3

2500

9000

Sales Officer

1

12000

144000

Sales man

4

6000

288000

Administration

Safety and security

10. Stores and Purchase Dept.

11. Marketing Section

Total

26835000

(c) Utility cost

= 0.2 TPC

(d) Maintenance and repairs = 0.1 FCI

= Rs. 10890970

(e) Operating supplies = 0.01 FCI

= Rs. 1089097

(f) Lab. Charges

= 0.025 TPC

(g) Patents and royalties

= 0.02 TPC

A = Direct production cost = (a) + (b) + (c) + (d) + (e) + (f) + (g) = Rs. 1744 x 106 + 0.245 TPC (B) Fixed Charges:(a) depreciation = 0.1 FCI + 0.03 (Building cost) = Rs. 10957300 (b)

Local taxes = 0.04 FCI + Rs. 4356388 151

(c) Insurance premium = 0.025 FCI So, B = F.C.

= Rs. 2722742 = (a) + (b) + (c) = Rs. 18036430

(C) Plant overheads

= 0.07 TPC

(D) General Expenses

= 0.07 TPC

(E) Interest = 0.11 TCI

= Rs. 15574087

Then, TPC

= (A) + (B) + (C) + (D) + (E)

So TPC

= Rs. 2462 x 106

13.6 PROFIT ANALYSIS Table-13.4 Product selling cost Material

Qty. kg. 6

Rate Rs./kg

Total Rs.

35

2450 x 106

ACN

70 x 10

AN

236 x 104

20

47.2 x 106

HCN

7968 x 103

10

79.68 x 106

TCS

= Rs. 2576.88 x 106

Gross Profit = TCS ±TPC

= Rs. 144.88 x 106

Tax paid = 0.4 x Gross Profit

= Rs. 45952000

Net Profit = Gross Profit ± Tax

= Rs.62.928 x 106

Payout period = Depreciable TCI / (Net Profit/year + Depreciation/year) = 1.25 years Rate of return = Net profit x 100 / TCI = 44.45 %

152

CHAPTER-14: UTILITIES

14.1 UTILITIES: The word utilities refer to the ancillary services needed in the operation of any production process. All the streams used in the plant other than reactants come under the head of utility. These are many streams which are being used by Acrylonitrile plant as utility. 14.2 STEAM SYSTEM: The steam is required for supplying heat the process fluid in the various equipments and for many outer purposes in the plant. For this purpose utilize heat evolved in reactor by using steam generating system. For extra requirement of steam can be produced in boiler is just like shell and tube heat exchanger. 14.2.1 Steam: There are three levels of steam in the plant. 1.

High Pressure Superheated steam.

2.

Medium Pressure Steam

3.

Low Pressure Steam.

The High Pressure saturated steam at 41.5 kg/cm2 and 2530C is generated in reactor cooling coils in the process of removing the exothermic heat of reaction. A major portion of the saturated steam produced is superheated in the reactor Superheat cooling coils. Super heated steam is controlled at 370 0C and used to drive the reactor air compressor. A small part of the high pressure saturated steam produced in used to control the temperature of the superheated steam by bypassing, the superheat coils. Some part of high pressure saturated steam is let down into medium pressure steam and some part in low pressure steam. Most of low pressure steam comes from the air compressor turbine. High Pressure Super Heated Steam: This steam is used to drive the turbine which drives the reactor air compressor, exhausting to the low pressure steam header.

153

Medium Pressure Steam: This steam is used in the catalyst hopper ejector, the product column ejector and the evacuation ejector for the purification reboilers. Low Pressure Steam: This steam is used in reboilers of columns, reactor steam quenches, steam service stations, deaerator, Start-up heater firebox purges, tower and tank steam purge. 14.2.2 Condensate System: Condensate is collected from the steam heated reboilers. Part of this condensate is returned to the reactor cooling system for reuse. A portion of the condensate is cooled and used to supply as required, water for various pump seals and auxiliary chemical make up requirements. 14.3 FUEL SYSTEM: Fuel oil is used as fuel. It is used in start up heater to heat the air from air compressors to approximately 4800C. Fuel oil is burnt in burners and air in tube is heated directly with flame. Fuel oil is also used in incinerator for burning ammonium sulphate, waste water and spent solution. 14.4 WATER SYSTEM: 14.4.1 General purpose Water: The water used for drinking, washing, flushing etc. purposed is considered as general purpose water. It is drawn from a river or lake. 14.4.2 DM Water: The Demineralized water is required as boiler feed water for steam generation. It is obtained from the DM water plant. 14.4.3 Cooling Water: The cooling water is drawn from a river or lake in sufficient quantity. It is required for providing cooling the materials in various heat exchangers for cooling. The hot water from heat exchangers is taken to cooling tower. The type of cooling tower is induced type. The temperature of water to cooling tower is 35-370C. The temperature of water from cooling tower is 25-270C.

154

Hot waters from the plant after the heat exchanging come to the cooling tower through one single header. There is no need to pump it to top of the tower as pressure at the discharge side is significant for the circulation of cooling tower through the piquet and to complete the cycle. (1) Cooling tower is a induced draft cooling tower where two exhaust fans all rotated. Majority part of cooling tower is made of wood blocks and cement sheets. (2) Hot water coming to the tower is sprinkled from the tower using plastic nozzle which passes through the tower flow metal baffles provided for adequate heat transfer. Air coming from side ways passes through the tower and due to exhaust fan carried to the top of the tower. (3) Flow rate of outgoing water from cooling tower is 2000 m3/hr and make up water provided is just 20 m3/hr approximately. (4) Evaporation and windage loses are almost 1% of the total flow rate. Temperature drop is 8 to 100C (maximum). (5) Due to continuous operation of cooling tower there are many problems which arises at the time of operation like to maintain pH of the water, scale formation to control algal formation etc. i)

To remove or control algae formation some biocides are added at proper

intervals of time. ii) If these are more free radicals of chlorine then that leads to corrosion problems moreover due to recirculation of water problem of scale formation also arises. Sodium hydrochloride is added in their respective proportion to handle the problem of scale formation and to maintain chloride level. iii) 98% H2SO4 is added continuously in very small amounts to maintain the pH level of the cooling tower. (6) Blow down system is also there to flush the tower and then to remove it rapidly so as to remove scale which has been formed at the bottom of the tower. 14.5 BRINE COOLANT ± REFRIGERANT: In acrylonitrile plant, Ethylene Glycol is used as coolant. Ethylene Glycol is used in various heater exchangers for cooling other material and thereby it is heated. This hot 155

brine is taken to brine refrigeration section. Here, compressors are working for refrigeration of brine. The refrigerated brine is at temperature 40C (390F) and it is taken to heat exchangers again for heat exchange. Refrigeration is required to maintain the temperature below that of the surroundings to keep the product in liquid form at low temperature and high pressure. There are two basic refrigeration cycles. 1)

Vapor-Compression cycle

2)

Absorption refrigeration cycle.

Vapor-Compression cycle: A Liquid evaporating at constant pressure provides a means for heat absorption at constant temperature Likewise, condensation of vapour, after compression to a high pressure, provides for the refection of heat at constant temperature. The Liquid from the condenser is returns to its original state by an expansion process. This can be carried out in a turbine from which work is obtained. For lower load, expander is replaced by tower valve which isentropic ally reduces the pressure. The refrigerant used is brine or ethylene glycol which is non hazardous and non poisonous. 14.6 AIR SYSTEM: 14.6.1 Plant Air System:Plant air is provided to all the air service stations throughout the production area. Plant air is also used for aeration of the catalyst in the catalyst drum during transfer operations, to pressurize the catalyst storage drum and for purging in various equipments and to keep tank under some positive air pressure etc. 14.6.2 Instrument Air System:All automatic control instruments are supplied with air if they are pneumatic controls. The air supplied to these instruments is called Instrument Air. The pressure of instrument air supply is constant at 1.4 kg/cm2 (20 lb/in2). Instrument air require for Acrylonitrile plant is generated at instrument air section. For that purpose atmospheric air filtered and fed to the compressor. 156

14.7 NITROGEN PRODUCTION PLANT: N2 is separated from air needed for industrial purposes there are basically three processes by which one can separate oxygen and nitrogen from air they are, 1) Cryogenic distillation. 2) Burning of any fuel with air 3) Adsorption using carbon molecular sieves. As cryogenic separation using distillation is very expensive hence it is not advisable to use this method keeping in mind the comparatively low demand of N 2 in the plant. Secondly N2 we get by distillation is highly pure containing almost no oxygen. For plant purpose that high purity is not required. Due to this reasons the company has opted for pressure swing adsorption of oxygen to get nitrogen stream which can be used for Acrylonitrile plant for various purpose. 14.8 ELECTRICITY: The electricity is required for motor drives, lighting and general use. It is generated onsite or purchased from GEB depending on the requirements. 14.9 STEAM GENERATING SYSTEM: 14.9.1 Heat removal from reactor and gases:As ammoxidation reaction of propylene is highly exothermic, heat must be removed from reactor to run the process smoothly. However, the process is finely adjusted such that the heat produced during reaction is utilized too run the steam turbine and thereby air compressor with high savings of electricity. For this purpose, a steam generation system is working. Condensate of steam from various heat exchangers reboilers comes to a condensate tank. With new make up D.M. Water feed. This boiler feed water from condensate tank flows to the deaerator under action of deaerator level controller. In deaerator, low pressure steam is added to heat the water and strip out dissolved gases. Hydrazine (N2H4) is also added to deaerator to react with oxygen dissolved is condensate water. Nitrogen and other gases are released from deaerator. Now, deaerated water is pumped by the feed water pump to Reaction Products gas cooler. Reactor Product gas cooler is a heat exchanger where reaction products gases 157

from reactor are passing through tube side and boiler feed water in shell side in counter current direction. The cooled gases are now taken to quench column. Water is heated to approximately 2300C. It comes to the coolant drum and then it is pumped by reactor coolant pump to the reactor cooling coils. Here, water absorbs heat from reactor. The steam and water mixture leaving the reactor cooling coils flows back to the coolant drum for separation of the steam and recirculation of the cooling water. Water from the discharge of reactor coolant pump is also recirculated to the inlet of the product gas cooler to control the temperature of product gases at 2320C for prevention of polymerization. The most of steam from top of coolant drum is taken to upper reactor cooling coils. Here, this steam is super heated to 370 0C and then it is used to run steam turbine. A small part of saturated steam (41.5 kg/cm2s, 2530C) from top of coolant drum islet down into the low pressure steam heater (3.5 kg/cm2g). However, most of the low pressure steam consumed in the plant comes from the air compressor turbine. A small quantity of high pressure steam is let down to medium pressure steam for using in the vacuum ejectors. Phosphate solution is added in coolant drum for maintaining pH of circulating water. Table-14.1 Utility Requirement: Utility Saturated steam at 110oC

Process water

Steam

Equipment

Flow rate kg/sec

Reactor coils

851

Product gas cooler

48

Quench Col

2.61

Absorber

9.55

Heat exchanges (Recycle)

2.84

Heat exchange (Recycle)

2.75

Recovery col. Reboiler

3.29

Aceto stripper Reboiler

1.58

HCN column Reboiler

1.08

ACN column Reboiler

0.66

158

Cooling water

Brine

Recovery col. Reboiler

48.27

Aceto stripper rubber

156.31

ACN column rubber

517.13

HCN condenser

434.15

159

CHAPTER-15: AUXILARY EQUIPMENTS

15.1 Columns 1) Quench Column: M.O.C.

= 316 S.S. clad [column] and Stone ware [Packing]

Type

= packed Tower --- 2 inch packing --- Tower divided into two sections.

2) Absorber: M.O.C.

= 316 S.S. clad [column] and 316 SS [trays]

Type

= Valve tray column

Tray spacing

= 0.6 m

No. of trays

= 40

3) Recovery column: M.O.C.

= 316 S.S. clad [column] and 316 SS [trays]

Type

= Valve trays

Tray spacing

= 0.5 m

No. of trays

= 60

4) Aceto Column: M.O.C.

= 316 S.S. clad [column] and 316 SS [trays]

Type

= Sieve tray

Tray spacing

= 0.5 m

No. of trays

= 30

5) HCN Column: M.O.C.

= 316 S.S. clad [ column and trays both]

Type

= Sieve tray

Tray spacing

= 0.6 m

No. of trays

= 20

6) Product Column: M.O.C.

= 316 S.S. clad [column] and 316 SS [trays] 160

Type

= Valve tray column

Tray spacing

= 0.6 m

No. of trays

= 40

15.2 Heat Exchangers: Ammonia and Propylene vaporizers and superheater: Shell

= Rubber lined

Tubes

= Graphite

Product gas cooler: Shell and Tubes

= Carbon steel

After coolers, and condenser of HCN column, Reboilers of Aceto and HCN column and condenser of HCN column: Shell

= Carbon steel

Tubes

= 316 SS

Rich / Lean water heat exchanger, Rich / Solvent water heat exchanger, Reboiler of Recovery column and product column: Shell and Tubes = 316 SS All Reflux drums, decanters have M.O.C. = 316 SS 15.3 Tanks: Ammonia storage: Store in bullets.

M.O.C.

= Carbon Steel

Store in spherical vessel. M.O.C.

= Carbon Steel

Propylene storage:

Acrylonitrile Tank: Closed vertical tank. HCN storage tank:

M.O.C.

= Carbon Steel

M.O.C.

= 316 SS

161

CHAPTER-16: SUMMARY

An exhaustive literature survey & market survey was made for the selection of the process for the manufacture of Acrylonitrile with all the advantages taken in general. Although this process is not fit for the smaller production, but seeing the growing demand in the country, at least few units of large scale are required. The production of Acrylonitrile by propylene ammonia air oxidation reaction process. Seems to be the most appropriate process. The process design was based on standard code and practices available in the literature. The performance of continuous flow fluidized bed reactor has been tented for the production distribution. Acrylonitrile is the most important industrial product with its demand growing everyday statistics show that there is a wide gap between demand and supply in the country and keeping in view the future demand, possibility of the gap getting wider is envisaged if the few production units are not put. Acrylonitrile production raw material propylene and ammonia are very hazardous and requires a safer way for handling, storage and transportation. So lots of care should be taken for there storage, handling and transportation.So safety is an important factor and a proper attention is to be paid for keeping its standard high as possible. Here a high degree of automation with computer aided analyzer is required for keeping the yieled % higher and also ensuring a better quality product. Acetonitrile by product has proven a good solvent competitor for acetone, particularly in the solvent extraction of butadiene and other dienes. Ultimately from this project report I conclude that from technical and economical point of view this project of acrylonitrile is viable. This project can pay back all our invested money in about 1.5yrs. (if than efficiently for 330 days). During running this project lots of precautions should be taken care of for safety of an organization, as the materials used in this project are very hazardous and flammable.

162

CHAPTER-17: REFRENCES 1) .LUN 2WKPHU³(QF\FORSHGLDRI&KHPLFDO7HFKQRORJ\´9RO3- 369, 4th Edition, John Wiley & Sons, New York, 1987 2) 8OOPDQQ¶V(QF\FORSHGLDRI,QGXVWULDO&KHPLVWU\9&+SXEOLFDWLRQV*HUPDQ\ Vol. A1, P. 177 - 183, 1985. 3) 0FNHWWD -RKQ - ³(QF\FORSHGLD RI &KHPLFDO 3URFHVVLQJ  'HVLJQ´ 0DUFHO Dekker

Inc.Publication,

4) Chemical and Process Technology Encyclopedia, D.M. Considine, McGraw Hill Book Company, P. 30 ± 35, 1974. 5) ³0F*UDZ +LOO (QF\FORSHGLD RI 6FLHQFH DQG 7HFKQRORJ\´9RO )LIWK edition,McGraw Hill Book Company. 6) 3HUU\ 5REHUW +  'RQ *UHHQ ³3HUU\¶V &KHPLFDO (QJLQHHUV¶ +DQGERRN´ Seventh and Sixth Edition, McGraw-Hill International Editions, Chemical Engineering Series, New York, 1998. 7) &RXOVRQ -0 DQG 5LFKDUGVRQ -) ³&KHPLFDO (QJLQHHULQJ´ )LUVW HGLWLRQ Vol.6, Pergamon Press ,Oxford, 1983. 8) 0F&DEH :/ 6PLWK -&  +DUULRW 3 ³8QLW 2SHUDWLRQV RI &KHPLFDO (QJLQHHULQJ´ )LIWK HGLWLRQ 0F*UDZ +LOO ,QWHUQDWLRQDO (GLWLRQV &KHPLFDO Engineering Series, New York, ,(1989). 9) 7UH\EDO 5( ³0DVV 7UDQVIHU 2SHUDWLRQV´ 7KLUG HGLWLRQ 0F*UDZ +LOO International Editions, Chemical Engineering Series, New York, (1981). 10)

SmiWK -0  9DQ 1HVV +& ´,QWURGXFWLRQ WR &KHPLFDO (QJLQHHULQJ

7KHUPRG\QDPLFV´)LIWKHGLWLRQ,QWHUQDWLRQDO(GLWLRQV&KHPLFDO(QJLQHHULQJ Series, New York, (1987). Symposiums and Journals: 1) Editing by Mossson Kwauk, Daizo Kunni, Zheng Jiansheng, Mansanodu +DVXWDQL ³)OXLGL]DWLRQ¶±6FLHFQH DQG 7HFKQRORJ\´-conference Pumps, Second Chain ± Japan Symposium, 10 to15 April, 1985, Science Press, Beijing, Chian, 1985. 163

2) ³:RUNVKRSRQGHVLJQDQG2SHUDWLRQRI+HDWWUDQVIHU 6\VWHP´  WR$SULO 1992), At: Seminar Hall, Chemical Engineering Dept., Vadodara, By IIChE, Baroda Regional Centre. 3) $SSOLHG 3RO\PHU 6\PSRVLD ³$FU\ORQLWULOH LQ 0DFURPROHFXOHV´ $W &KLFDJR Jllinois, August 27-29, 1973, By the Maconomelecular Secrretariat of American Chemical Society, Editor Eli M. Pearce, John Wiley and sons pub.  6HPLQDURQ³+D]DUGVLQ&KHPLFDO,QGXVWU\- Technology, Prevention and 5HPHGLHV´ Organized by IIChE, Baroda and Ahemadabad Regional Center, on 2nd March 1985 at Research Center Auditorium, IPCL, Baroda.  ³6DIHW\DQG/RVV3UHYHQWLRQLQWKH&KHPLFDODQGRLO3URFHVVLQJ,QGXVWULHV´ No 120. The Institution of chemical Engineers, Rugby, UK Hemesphere Publishing Corporation. 6) S.P. Lankhuyzen, P.M. Florack, and H.S. Van Der BAAN, Journal of Catalyst, Vol. 42, P 20-28, April ±June 1976. 7) W. Keith hall, Frank S. Stone (editors), Journal of Catalyst, Volume87, P 363380, May ± June 1984. 8) A.N. Orlov, S.G. Gaganbn, Kinetic and Catalysis, P 1308-13011, June 1975. 9) J.M. Berty, Chemical Engineering Progress, Vol. 70, No.5, P. 78-84, May 1974. 10)P.R. Prabhu, Chemical Age India, Vol.36, No.9, P 827-829, September 1985. 11)Stobaugh, R.B., Hydrocarbon processing, Vol.50, P. 109-120, January 1971. 12)F. Veatch, J.L. Callahan, J.D. Ideal, Jr. and E.C. Milberger, Chemical Engineering Process, Vol.50, No.10, P. 65-67, October 1960. 13)J.L. Callahan, E.C. Milaberger, R.K. Grasselli, and H.A. Strecker, Industrial and Engineering Chemistry Product Research and Development, Vol.9, No.2, P. 134-142, 1970. 14)R.B. Stobaugh, S.G. Mcti Clark and G.D. Camirand, Hydrocarbon Processing, Vol.50, P. 109-120, January 1971. 15) Roland Nilsson and Arne Andersson, Industrial and Engineering Chemistry 164

Research and Development, Vol.36, P.5207-5219, 1997.

Websites:www.rockbridgegroup.com www.chemdat.de www.ipcl.co.in www.inchem.org www.safetyinfo.com

165

CHAPTER-18: APPENDICES

18.1 APPENDICES NO. 1: Raw Material Specification: 1. Propylene (C3H6):Molecular weight

= 42.03

Purity

: 85% minimum

C2H4

: 5% maximum

C4H6

: 0.1% maximum

C2H2

: 0.1% maximum

Methyl Acetylene/Prop. Butadiene

: 0.75 maximum

H2S

: 10 ppm maximum

S (free)

: 50ppm maximum

2. Ammonia (NH3):Molecular weight

= 17.03

Purity

: 95.5% minimum

3. Air:Molecular Weight Purity

= 29 : Free of dust, oil and chemicals.

4. Catalyst 49MC: Typical chemical analysis Approximate weight

Percent

Potassium

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