Thermal degradation and gasification characteristics of Tung Shells as an open top downdraft wood gasifier feedstock Lalta Prasad, B. L. Salvi & Virendra Kumar
Clean Technologies and Environmental Policy Focusing on Technology Research, Innovation, Demonstration, Insights and Policy Issues for Sustainable Technologies ISSN 1618-954X Clean Techn Environ Policy DOI 10.1007/s10098-014-0891-8
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Author's personal copy Clean Techn Environ Policy DOI 10.1007/s10098-014-0891-8
ORIGINAL PAPER
Thermal degradation and gasification characteristics of Tung Shells as an open top downdraft wood gasifier feedstock Lalta Prasad • B. L. Salvi • Virendra Kumar
Received: 13 August 2014 / Accepted: 4 December 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Tung (Aleurites Fordii) is cultivated in China, Argentina, Paraguay, Africa, India, and United States. Tung oil has various applications like as a drying agent for paints and varnishes, termite control as well as cleaning and polishing compounds. The Tung shell and de-oiled cake are residues after decortications of the Tung seeds. This paper has been aimed for thermal degradation and gasification of Tung shells. Thermal degradation of the Tung shell was carried out at heating rates of 10, 15, and 20 °C/min from room temperature to 750 °C under nonisothermal conditions, and N2 was used as a carrier gas. Based on the thermogravimetric analysis and differential thermogravimetric analysis results, it was found that Tung shells have low thermal stability. These shells were gasified in the downdraft wood gasifier. The calorific value of producer gas was calculated to be 4.75 MJ/Nm3. The conversion efficiency of the gasifier for Tung shells was higher (93 %) as compared to the wood (84 %). The producer gas generated from shells could be used for heat and or power generation for rural areas. Also a solution to reduce the disposal problem of toxic Tung shells generated from oil expellers.
L. Prasad (&) Department of Mechanical Engineering, G.B. Pant Engineering College, Pauri Garhwal 246194, Uttarakhand, India e-mail:
[email protected] B. L. Salvi Department of Mechanical Engineering, College of Technology and Engineering, Maharana Pratap University of Agriculture and Technology, Udaipur 313001, India V. Kumar Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India
Keywords Tung shell Activation energy Downdraft gasifier Producer gas Gasifier conversion efficiency
Introduction Tung tree comes from the rocky subtropical foothills of Western China. It is cultivated in China, Argentina, Paraguay, Africa, India, and United States as reported by Potter (1957). The increasing commercial importance of the Tung oil encouraged its introduction and cultivation in countries outside China (Ma et al. 2007). Sharma et al. (2011) reported the important information on Tung tree. Tung tree usually bears fruit when they are 2–4 years old and reach maximum productivity at around 10–12 years of age. The average life span of a Tung tree is 30 years. Okuda et al. (1975) reported the oil content in various parts of Tung fruit between 14 and 20 %, in the kernel 53–60 %, and in the seed 30–40 % of fruit weight. The dry fruit contains three seeds as shown in Fig. 1. The useful information on the use of Tung oil is reported in the Wealth of India (1994). Still, there is no literature available for utilization of Tung residue (shells and de-oiled cake), which are toxic in nature. Tung residue is a lignocellulosic material, which does not find any application either in agriculture or animal feeds. Many researchers have continuously paid special attention to convert agricultural wastes into solid, liquid, or gaseous fuels using thermochemical conversion (TCC) technologies (Gai et al. 2013). Pyrolysis could be a better option for residue utilization (such as shells and de-oiled cake of Tung shells). The products of pyrolysis are easier to transport, store, handle, and it can be utilized in decentralized manner. Many researchers [Demirbas (2001), Manya et al. (2003), Varhegyi et al. (1997), Raveendran et al. (1995), Sricharoenchaikul and
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Fig. 1 Tung fruit, seeds, and shells
Atong (2009), Paradela et al.(2009)] reported that the pyrolysis is an extremely complex process; it generally goes through a series of reactions and can be influenced by many factors (like temperature, heating rate, reactor type, reaction time, and biomass particle size). The increase in reaction temperature results in a decrease of the liquid fraction and a corresponding increase of the gas and char products. According to White et al. (2011), a thorough understanding of pyrolysis kinetics is vital to supply guidance on the feasibility, design, and scaling of industrial gasification reactors, as well as pave the way for optimizing the operating conditions. Gai et al. (2013) carried out thermogravimetric analysis of agricultural residue under non-isothermal conditions. The non-isothermal method has become a widespread analytical technique in recent decades due to the high sensitivity to experimental noise compared to isothermal methods. Thermochemical gasification is another important route for converting the residue/waste into combustible gases. The product gas has a great potential since it can be directly used for the production of heat and electricity as reported by Karmakar and Datta (2011), Septien et al. (2012). The classification of the gasifiers based on the flow pattern between the gas and biomass, the method of contact between the fuel and gas, and the heating mode used has been discussed by Cheng (2010). The conical spouted bed reactor was used for the continuous steam gasification of waste plastics by Erkiaga et al. (2013). During the last decade, the internal circulating fluidized bed (ICFB) also called dual bed has been successfully applied to biomass gasification. The dual bed gasification is suitable even when a relatively low reactivity fuel is used, such as the brown coal as reported by Kern et al.(2013), Miccio et al. (2012). Ahmed et al. (2013) developed the kinetic model for steam gasification of palm kernel shell with in situ CO2 capture and tar reduction. They found that the amount of hydrogen produced during gasification process was increased at higher temperatures. The yield of the product gas was also increased with increase in temperature. More recently Brau et al. (2013) conducted a study on hydrogen utilization for oil refining via biomass indirect steam gasification. Link et al. (2012) carried out the study on
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gasification of untreated and leached olive residue, and cogasification of olive residue, reed, pine pellets, and douglas fir wood chips in an atmospheric fluidized bed gasifier. Gurung and Eun (2013) conducted the study on densification of biomass, and they suggested that the biomass briquetting and pelletization are another efficient bioenergy technology, converting low bulk density biomass into high density and energy concentrated fuel briquettes/pellets. Isaksson et al. (2014) suggested the biomass pretreatment methods before gasification, and Fischer–Tropsch (FT) crude production may also be used. Each method has its advantages and disadvantages. Promoting the use of biomass resources increases the system costs, which helps for conservation of environment from global warming, waste/residue management, CO2 emissions reduction, and generation of income to local communities, which encourages energy plantation. It will help electrify remote villages where grid extension is not possible or feasible, thus resulting in a green environment as reported by Herran and Nakata (2012) and Sikdar (2013). The information on kinetic analysis of pyrolysis and gasification of Tung shell was hardly reported in the literature. Therefore, the main objective of this study is to investigate the variation of pyrolysis kinetics of Tung shells at different conversion fractions and reaction temperature. The pyrolysis kinetics of Tung shells obtained in the current study can give a better and more comprehensive understanding of the pyrolysis process and a proper design of a pyrolysis reactor, as well as to help establish the kinetic model of biomass gasification for design and scaling of industrial gasification reactors.
Materials and methods Characterization of biomass material The raw biomass of Tung shells was collected from the oil processing industry in the state of Assam, India. One kg of Tung shells were sun dried, crushed, and sieved to produce the particles with the size less than 297 microns for thermophysical properties. The physical and chemical properties (proximate and ultimate analysis) of the Tung shells are given in Table 1. Proximate analysis of the samples was carried out by (Indian Standards) IS: 1350(P-1)1984 test method, and ultimate analysis was done by IS: 1350(P-4) (Sec-1)1974 and IS: 1350(P-4) (Sec-2)1975. Experimental conditions for thermogravimetric analysis (TGA) For the physico-chemical and thermal characterization of Tung shells, a sample of approximately 1 kg of biomass
Author's personal copy Characteristics of Tung Shells Table 1 Proximate analysis (% wet basis) and ultimate analysis (% dry basis) of Tung shell Sample
Tung shell *
Proximate analysis (% wet basis)
Ultimate analysis (% dry basis)
Moisture (%)
Volatile matter (%)
Fixed carbon (%)
Ash (%)
C (%)
H (%)
N (%)
O* (%)
Bulk density (kg/m3)
Calorific value (MJ/kg)
8.66
83.83
4.51
3.0
58.40
7.12
0.42
31.06
342
16.71
by difference
residue was further oven-dried at 105 °C for 1.5 h and ground in a laboratory electric grinder. The ground residue was further classified by using one IS sieve of mesh size 50 (0.297 mm). The sieved powdery samples having size distribution less than 0.297 mm were stored in airtight containers. The Perkin-Elmer TGA-7 thermogravimetric analyzer was used to analyze the thermal characteristics of the Tung shells. The brief specification of TGA-7 is given below: balance sensitivity = 10-4 mg, balance accuracy = better than 0.1 %, weighing precision = up to 10 ppm, temperature range = ambient to 1,000 °C, heating and cooling rates = 0.1–1,000 °C/min in 0.1 °C increments, temperature precision = ± 2 °C, response time = B 6 s, temperature sensor = chromel–alumel thermocouple. Three samples of Tung shells were pyrolyzed (sample weight in the range of 1.2–1.8 mg) with heating rates of 10, 15, and 20 °C/min, respectively, in the temperature range from room temperature to 750 °C. Nitrogen was used as a carrier gas with a flow rate of 20 ml/min throughout the experiment.
stoichiometric of the decomposition reaction. Here a is the conversion fraction of the mass reacted in time t relative to the final mass. Downdraft wood gasifier
In the literature, various methods are available for kinetic modeling of biomass materials. In the present study, the differential method is used for kinetic modeling of the Tung shells.
Figure 2 shows the overall view of the 20 kWe downdraft gasifier (Height of gasifier = 2,930 mm, Reactor inner diameter = 250 mm, Reactor outer diameter = 500 mm, Throat diameter = 180 mm, Nozzle height from top = 1,810 mm, Nozzle diameter = 30 mm) system which is used in the present study. The Tung shells with moisture content of 8.66 % were loaded into the reactor and ignited by holding a flame in the form of wick near each air nozzle. The temperature variation in various zones (preheating, drying, pyrolysis, oxidation, and reduction zones) of the gasifier was measured by using S-type thermocouples. The heights of preheating, drying, pyrolysis, oxidation, and reduction zone were 1,000, 1,600, 1,670, 1,840, and 2,010 mm, respectively, from the top of the gasifier. The location and position of the thermocouples were fixed for each zone of the gasifier. Eight channels data logger with computer interface was used for temperature recording. Thermocouples were inserted from the top of the gasifier before charging the gasifier. After 10–15 min of operation, the producer gas was generated, and it was ignited in the burner to check the quality of the gas.
The differential method
Results and discussion
The differential method, as given in the literature reported by many researchers[Wang et al.(2009); Murugan et al.(2008); Mansaray and Ghaly(1999)], was used to obtain the pyrolysis kinetic parameters from the Thermogravimetric data, and thus, the kinetics of most reactions under non-isothermal conditions can be summarized by the following general Eq. (1). da 1a E ln ð1Þ ¼ ln A dt 1 XC RT
Thermogravimetric analysis
Kinetic modeling
where T is the absolute temperature, A is the pre-exponential factor, E is the activation energy, R is the universal gas constant, and Xc is called char fraction by
Thermogravimetric analysis (TGA) curves are used in the determination of kinetic parameters for pyrolysis of Tung shells in nitrogen environment. Figure 3 shows the degree of conversion (mass loss) versus temperature for dynamic experiments at heating rates of 10, 15, and 20 °C/min for Tung shells. It can be noticed from the TGA curves (Fig. 3) that the mass loss occurs in three steps, and the curve shifts to the right for higher heating rates. The major decomposition of Tung shells occurred between 178 and 418 °C at 10 °C/min. The mass loss in the early stage may be attributed to the loss of traces of
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Author's personal copy L. Prasad et al. Fig. 2 3D image of downdraft gasifier shows the locations of thermocouples (TC) from top of the reactor
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HR 10 Deg. C/min HR 15 Deg.C/min HR 20 Deg.C/min
80 60
Stage-I
Stage-II
-dα/dT (%/oC)
Mass loss (%)
100
Stage-III
40 20 0 0
100
200
300
400
500
600
700
800
Temperature (oC)
0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00
HR 10 Deg. C/min HR 15 Deg. C/min HR 20 Deg. C/min Stage-I
0
100
Stage-III
Stage-II
200
300
400
500
600
700
800
Temperature (oC)
Fig. 3 Comparison of TGA curves of the Tung shell at different heating rates (HR)
Fig. 4 Comparison of DTGA curves of the Tung shell at different heating rates (HR)
moisture as bound water on the surface and the pores of the samples. The values of temperature range (TR) and peak temperature (PT) shift to higher temperature upon increasing the heating rate from 10 to 20 °C/min. The first mass loss occurred from room temperature to 178 °C for all the samples, the second occurred between 178 and 420 °C, and the third occurred between 420 and 750 °C for Tung shells.
The pyrolysis characteristics and DTGA curves of the Tung shell are shown in Fig. 4. The pyrolysis of Tung shell started at 178 °C, its mass loss rate (DTGA curve) increases sharply with increase in temperature and reaches its maximum value at 317, 321, and 324 °C for heating rates of 10, 15, and 20 °C/min, respectively. When the temperature was over 385 °C, its mass loss rate was low 0.110 (%/oC), 0.105 (%/oC), and 0.097 (%/oC), and the corresponding amount of solid residue was 12.14, 13.55, and 13.81 % for heating rates of 10, 15, and 20 °C/min, respectively. The similar trend was observed in the pyrolysis of Palm oil waste study carried out by Yang et al.(2006). They found that the pyrolysis of water-washed palm oil waste (shell) increased with increasing temperature, and its maximum mass loss rate was less than 0.7 (%/oC) at 362 °C. At higher heating rates, slower heat transfer from the exterior to the interior of the biomass particle would lead to a temperature gradient, giving a
Differential thermogravimetric analysis The differential thermogravimetric analysis (DTGA) curves (Fig. 4) for Tung shell showed two peaks of mass loss. The first peak shows major mass loss, followed by a second mass loss peak, which is small as compared to the first mass loss peak. This is due to degradation of hemicellulose and cellulose, followed by slow rate of decomposition of lignin at a higher temperature 580 °C (approximately).
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lower temperature at the core. This further leads to reduced volatilization of the mass at the core. Also, at higher temperatures, diffusional rates of the cracked products out of the particles would be slower than the chemical reaction rate. Many researchers [Ramadhas et al. (2008); Hajaligol et al. (2001); Sharma et al. (2004); Yang et al. (2007)] have investigated the effect of structural components of biomass on thermal decomposition. The cellulose, hemicellulose, and lignin are three basic components in the plant material (biomass). The thermal degradation of these constituents depends on pyrolysis temperature. The cellulose content in the biomass may enhance the ignition characteristics and decomposition of lignin, since the cellulose compounds have the structure of branching chain of polysaccharides and no aromatic compounds, which are easily volatilized at low temperatures. Lignin is harder to decompose than cellulose since lignin contains benzene rings. Kinetic modeling and activation energy Apparent activation energy, E, is determined from the relationship between ln(da/dt) and 1/T from Eq. (1). Thus, a family of parallel straight lines of slope –E/R can be obtained from which the apparent activation energy (E) corresponding to the selected conversion is calculated. The average apparent activation energy of the Tung shell, up to 70 % conversion of the sample, as obtained by differential method is 28.38 kJ/mol. The average activation energy of Tung shell (28.38 kJ/mol) is quite low as compared to corn straw (129 kJ/mol) and rice husk (79 kJ/mol) as reported by Gai et al. (2013). Since the value of apparent activation energy represents the minimum energy required to break the chemical bonds between atoms, which means the higher value of the apparent activation energy, slower is the reaction. The activation energy indicates the reactivity and sensitivity of overall reaction rate. The result from TGA analysis indicates that Tung shell has low thermal stability, high reaction rate, and less solid residue at the end of the pyrolysis process. The Tung shell pyrolysis can be carried out at moderate temperature and low heating rate (10 °C/min). The Tung shell has good potential as feedstock for gasification and may be used for downdraft gasifier application, where the Tung shell is available in abundance locally. Gasification of Tung shells The Tung shells were loaded in the reactor, and gasifier was run in suction blower mode. Shells were ignited by using wick near each air nozzle as discussed in downdraft wood gasifier section. It was observed that after 15 min of flaring, producer gas was generated and it was ignited in
the bubbler, a blue flame was obtained which showed a good quality of the producer gas. The average temperatures in the preheating and drying zones were nearly same at 33 and 36 °C, respectively. The maximum temperatures measured in the oxidation and the reduction zones were found to be 1,098 and 936 °C, respectively. During gasification of shells, there was no agglomeration and blocking of the gasifier. The complete gasification of shells could not be achieved because of irregular shape of shells and gap between the conical grate and reactor wall. Even though a high local temperature (average temperature in the reduction zone was 758 °C) in the gasifier was not sufficient for complete gasification of shells. The residence time and heating rate also affect the gasification process. Yin et al. (2012) observed that a higher temperature (above 850 °C) in the oxidation zone helps in easy cracking of tar. This results in low tar content in the producer gas. The quality of the producer gas (calorific value) was good as compared to the wood gasification for same operating conditions (two air nozzles opened and top opened) of the gasifier as shown in Table 2. The irregular shape of the Tung shells and gap between the conical grate and reactor wall are the main causes of low carbon conversion. The composition of the producer gas was not varying much during gasification of shells (% deviation is very small) H2 = 13.45 % (± 0.63 %), CO = 18.98 %(± 0.74 %), CH4 = 1.56 % (± 0.21 %), CO2 = 12.34 %(± 0.74 %), and N2 = 53.67 % (± 1.92 %). Calculations for operating parameters of the gasifier Assuming chemical properties of biomass are Carbon, Hydrogen, Oxygen, and Nitrogen, chemical reaction equation for shell gasification can be written as n Cx Hy Oz Nk þ n/ðO2 þ 3:76N2 Þ ! x1 CO2 þ x2 CO þ x3 H2 þ x4 N2 þ x5 CH4 þ x6 O 2 : Using ultimate analysis of shell from Table 1 and Molecular Weight of Carbon, Hydrogen, Oxygen, and Nitrogen to calculate x, y, z, and k. Based on the
Table 2 Composition of Producer gas generated from Tung shells gasification Biomass
Producer gas composition (%)
Calorific value of Producer gas (MJ/Nm3)
H2
CO
CH4
CO2
N2
Tung shells*
13.45
18.98
1.56
12.34
53.67
4.75
a
14.95
17.03
1.04
11.46
55.55
4.49
Wood a
Susastriawan (2009); * present study
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thermochemical analysis of the Tung shells, the values of x, y, z, and k are to be calculated as 4.886, 7.120, 1.941, and 0.03, respectively.
H2 = 0.090 kg/Nm3; CH4 = CO = 1.250 kg/Nm3; 3 0.717 kg/Nm ; CO2 = 1.977 kg/Nm3; N2 = 1.257 kg/Nm3) was given by Tewari(1999)
ðCOvol qCO Þ þ ðH2 vol qH2 Þ þ CH4 vol qCH4 þ ðCO2vol qCO2 Þ þ ðN2vol qN2 Þ qg ¼ 100 ð18:98 1:250Þ þ ð13:45 0:090Þ þ ð1:56 0:717Þ þ ð12:35 1:977Þ þ ð53:67 1:257Þ : ¼ 100 ¼ 1:18 kg=Nm3 :
ð6Þ
Operating parameters of gasifier
6 Energy released per kg of shells
1 Gas flow rate: The mass flow rate of the producer gas is measured using Eq. (2) as given by I.I.Sc Operation & Maintenance Manual; pffiffiffiffiffiffiffiffiffi m_ g ¼ 3:3 Dhw þ 1:755; ð2Þ
The Eq. (7) was used to calculate the energy released from the gasification of shells.
where
7 The conversion efficiency of gasifier
Dhw ¼ Manometer differential height ðmmÞ: 2 Air–fuel ratio
Calculation based on 1 kg shells.
ðA=F Þs ¼ 4:76 /:
ð3Þ
3 Calorific value of producer gas Calculation for calorific value of producer gas was done on the basis of calorific value of each compound (the calorific value of compound CO = 12.71 MJ/Nm3; H2 = 12.78/Nm3; CH4 = 39.76 MJ/Nm3) were given by Iyer et al. (2002). The following equation was used to calculate the calorific value of producer gas: ðCOvol CVCO Þ þ ðH2 vol CVH2 Þ þ ðCH4 vol CVCH4 Þ 100 % ð18:98 12:71Þ þ ð13:45 12:78Þ þ ð1:56 39:76Þ ¼ 100 % ¼ 4:75 MJ/Nm3 :
QCVg ¼
ð4Þ 4 Mass of producer gas generated per kg of shells One kg mass of Tung shells used to produce 100 mol of dry producer gas. Therefore, mass of dry producer gas produced per kg of Tung shells is calculated using following formula: mg ¼
Rxi MWi ; n
ð5Þ
where Rxi MWi ¼ ðx1 MWÞCO2 þ ðx2 MWÞCO þ ðx3 MWÞH2 þ ðx4 MWÞN2 þ ðx5 MWÞCH4 : 5 Density of producer gas The density of producer gas is calculated at NTP i.e., at 273 K. The density of producer gas required density of each compound (the density of compound
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Eg ¼
mg QCVg : qg
ð7Þ
The gasification efficiency of the gasifier is depending on energy released per kg of shells and calorific value of shells. The following equation was used to determine the conversion efficiency of the gasifier or coefficient of thermal conversion. g¼
Energyr released per kg of shells : Calorific value of shells
ð8Þ
Therefore, conversion efficiency of gasifier is calculated as below: Eg 100 % QCVshells : 15:67 MJ= kg of shells 100 % ¼ 93:78 %: ¼ 16:71 MJ/kg of shells
g¼
Three samples of producer gas were collected into Tedlar bags of 0.5-liter capacity each. Each collected sample was analyzed thrice using the gas chromatograph unit. A gas chromatograph unit (Model GC7720/TCD, with column diameter 1/8 inches, solid, carbosphere of mesh range 80/100) was used to measure the composition of the producer gas. The analyzed gases were CO, H2 CH4, CO2, and N2. The calorific value of the producer gas was 4.75 MJ/Nm3 generated with Tung shells gasification, and energy release per kg of shells was 15.67 MJ/kg. The conversion efficiency of the gasifier was calculated to be 0.93. The quality of the producer gas generated from Tung shells (calorific value 4.75 MJ/Nm3) was higher as compared to the wood (4.49 MJ/Nm3) gasification as shown in Table 3. Keche et al. (2014) carried out the study of gasification for various biomass materials in downdraft
Author's personal copy Characteristics of Tung Shells Table 3 Parameters calculated for producer gas generated from Tung shells gasification in downdraft wood gasifier Wooda
Parameters
Tung shells*
Gas flow rate (g/s)
9.62
Mole of biomass (n)
7.30
10.86 6.76
Mole of air (/) Air–fuel ratio stoichiometric (A/F)s
2.01 9.57
2.11 10.04
Calorific value of gas Qcvg (MJ/Nm3)
4.49
4.75
Mass of gas generated mg (kg of gas/kg of shell)
3.54
3.89
25.82
26.29
Molecular Wt. of producer gas 3
Density of gas, qg (kg/Nm ) Energy released per kg of biomass, Eg(MJ/kg of shell) Conversion efficiency of gasifier (g) a
Susastriawan(2009);
*
1.16
1.18
13.70
15.67
0.84
0.93
Present study
gasifier. They reported that the calorific value of producer gas generated from Babul wood was 4.78 MJ/Nm3, and conversion efficiency of the gasifier was 0.79. The gasification trends of the present study are similar to those obtained by Keche et al. (2014).
Conclusions The study on Tung shells was carried out as an alternative source of energy through pyrolysis and thermochemical gasification using downdraft wood gasifier. The pyrolysis process of Tung shells was achieved in three different mass loss regions. A low heating rate (10 °C/min) was suitable for thermal degradation of the Tung shell, resulting in less amount of residue (char). The maximum peak temperatures were recorded for second and third stage of decomposition in the range of 317–341 °C and 478–538 °C, respectively. The average activation energy was 28.38 kJ/mol calculated by differential method. Based on the TGA/DTGA results (low heating rate, maximum temperature less than 550 °C ,and less solid residue), Tung shells were gasifying in the downdraft wood gasifier. The producer gas generated from the Tung shells has higher calorific value (4.75 MJ/Nm3) as compared to the wood (4.49 MJ/Nm3) for same operating conditions. The conversion efficiency of the gasifier of Tung shells was higher (93 %) as compared to the wood (84 %). The present study shows that the downdraft gasifier operated on Tung shells produces the better results compared to woody biomass materials as reported by various researchers. A few modifications in the grate diameter (use of smaller diameter) of the existing gasifier could enhance the quality producer gas. The producer gas could be used for heat and or power generation for rural
areas. The gasification of Tung shells would reduce the disposal problem of this toxic waste. Acknowledgments We would like to express thanks to Mr. Shiv Kumar Upadhyay, Department of Textile Engineering, and the staff of the Internal Combustion Engines Laboratory of the Mechanical Engineering Department, Indian Institute of Technology Delhi, New Delhi for providing necessary help during the course of the experimental work.
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