DOMAIN - HDT. Buoyancy Model. Buoyant. Buoyancy Reference Density. 2.6 [kg/m³]. Gravity X Component. 0.0 [m/s²]. Gravity Y Component. 0.0 [m/s²]. Gravity Z ...
DEVELOPMENT OF A REACTION MODEL FOR A HDT REACTOR WITH THE USE OF CFD A. O. Silva, A. S. Ferreira, V. P. de Souza, C. A. A. Monteiro and J. R. Nunhez University of Campinas – UNICAMP – Brazil School of Chemical Engineering Laboratory of Computational Fluid Dynamics
PRESENTATION TOPICS
• L-CFD Overview; • Problem Description; • Methodology; • Goals;
• Conclusion and next steps.
LABORATORY OVERVIEW
Laboratory of Computational Fluid Dynamics. State University of Campinas, Campinas, Brazil. Prof. José Roberto Nunhez Main Topics Research • Hydrotreating Reactors; • Experimental and CFD applied to Stirred Tanks; • Static Mixers; • Petrochemical Fired Heaters; • Effluent dispersion in river sections; • Environmental studies in animal farms.
HYDROTREATING Applied to Petroleum Fractions
Achieve low Sulfur content Achieve low Nitrogen content Achieve higher Quality
TRICKLE BED REACTORS
Inlet distributor tray Quench Catalyst
Cerâmica balls Catalyst support
Figure. Hydrotreating reactor Source:Ancheyta, 2011
TRICKLE BED REACTORS
• It is used in many processes: – Petrochemical; – Fine chemical; – Biochemical.
Figure. Hydrotreating Reactor
METHODOLOGY
Domain Identification
Studied Case
Problem definition
Objetives
Pre-processing Geometry Mesh Setup Convergence Criterion
Solver Computational Solution
Real Representation Experimental results Literature Post-Processing Analysis results
Figure. CFD solving methodology
METHODOLOGY Industrial Scale
Laboratory Scale
• Pressure Drop • Conversion • Holdup
Domain
Figure. Computational Domain
Source:Modified from Ancheyta, 2011
METHODOLOGY REACTOR CARACTERISTICS (CHOWDHURY, 2002) Diameter
0,019m
Height
0,5m
Reactive zone
0,25m
Bed porosity, 𝜀
0,5
Catalyst volume fraction inside the reactor Bulk Density, 𝜖𝑏
0,44
820 kg/m³
Inert particles 0,15m
Catalyst particles 0,25m
Liquid Gas
Inert particles 0,10m
METHODOLOGY PRE-PROCESSING – GEOMETRY, MESH AND BOUNDARY CONDITIONS
Figura–Hexahedral mesh (600.000 elements)
METHODOLOGY MODELING
Reaction and Kinect – Chowdhury, 2002 • Desulfurization 𝑆𝑢𝑙𝑓𝑢𝑟 + 2𝐻2 ⇒ 𝐻2 𝑆 + 𝐴𝑟𝑜𝑚𝑎𝑡𝑖𝑐 • Dearomatization 𝑃𝑜𝑙𝑦𝑎𝑟𝑜𝑚𝑎𝑡𝑖𝑐 + 𝐻2 ⇒ 𝐷𝑖𝑎𝑟𝑜𝑚𝑎𝑡𝑖𝑐 𝐷𝑖𝑎𝑟𝑜𝑚𝑎𝑡𝑖𝑐 + 2𝐻2 ⇒ 𝑀𝑜𝑛𝑜𝑎𝑟𝑜𝑚𝑎𝑡𝑖𝑐 𝑀𝑜𝑛𝑜𝑎𝑟𝑜𝑚𝑎𝑡𝑖𝑐 + 3𝐻2 ⇒ 𝑁𝑎𝑝ℎ𝑡𝑒𝑛
METHODOLOGY MODELING
Interphase Interaction - Attou and Ferschneider(1999) • Gas–Liquid • 𝐹𝐺𝐿 = 𝜀𝐺
𝐸1 𝜇𝐺 1−𝜀𝐺 2 2 𝑑2 𝜀𝐺 𝑝
0.667 𝜀𝑆 1−𝜀𝐺
+
0.333 𝐸2 𝜌𝐺 (𝑈𝐺 −𝑈𝐿 )(1−𝜀𝐺 ) 𝜀𝑆 𝜀𝐺 𝑑𝑝 (1−𝜀𝐺 )
• Gas-Solid • 𝐹𝐺𝑆 = 𝜀𝐺
0.667 𝐸1 𝜇𝐺 (1−𝜀𝐺 )2 𝜀𝑆 2 𝑑2 𝜀𝐺 (1−𝜀𝐺 ) 𝑝
• Liquid-Solid • 𝐹𝐿𝑆 =
𝐸1 𝜇𝐿 𝜀𝑆 2 𝜀𝐿 2 𝜀𝐿2 𝑑𝑝
+
𝐸2 𝜌𝐿 𝑈𝐿 𝜀𝑆 𝜀𝐿 𝑑𝑝
0.333 𝐸2 𝜌𝐺 𝑈𝐺 (1−𝜀𝐺 ) 𝜀𝑆 + 𝜀𝐺 𝑑𝑝 (1−𝜀𝐺 )
METHODOLOGY MODELING
Porosity Distribution - (BAZMI, HASHEMABADI e BAYANT, 2011) 𝐶. 𝑟 𝑒𝑥𝑝 𝑑𝑝
𝜖 = 𝜖𝑏 − 𝐷 + 1 − 𝜖𝑏 − 𝐷
i 1
D
C
0,045 -0,1252
2
-
-
3
-
-
𝑟 𝑎𝑖 𝑑𝑝
3
2
+ 𝑖=1
b
a
0,0479
-1,803
0,3566
1,185
0,001925 0,02649
𝑟 𝑑𝑝
3+2 𝑖−1
2
+ 𝑏𝑖
METHODOLOGY MODELING
Voidage
Porosity Distribution - (BAZMI, HASHEMABADI e BAYANT, 2011)
1,2 1 0,8 0,6 0,4 0,2 0
Top
0
2
4
6
8
10
Distance from center, x/dp Figure – Porosity distribution
Bottom
METHODOLOGY MODELING – DOMAIN DOMAIN - HDT
DOMAIN - HDT Liquid Morphology Gas Morphology
Continuous Fluid Continuous Fluid
Buoyancy Model
Buoyant
Buoyancy Reference Density
2.6 [kg/m³]
Gravity X Component
0.0 [m/s²]
Gravity Y Component
0.0 [m/s²]
Gravity Z Component
-9.81 [m/s²]
Buoyancy Reference Location
Automatic
Domain Motion
Stationary
Reference Pressure
4.00 [MPa]
Heat Transfer Model
Isothermal
Fluid Temperature
340.00 [C]
Homogeneous Model
False
Turbulence Model Homogeneous Model
Fluid Dependent False
METHODOLOGY MODELING – BOUNDARY CONDITIONS TOP - INLET
BOTTOM - OUTLET
Flow regime:
Subsonic
Flow regime:
Subsonic
Turbulence:
Fluid Dependent
Turbulence:
Fluid Dependent
Mass and Momentum:
Fluid Velocity
Mass and Momentum:
Static Pressure
WALL - WALL Mass and Momentum:
No Slip Wall
Wall Roughness:
Smooth Wall
METHODOLOGY MODELING – SOLVER INFORMATION
Numerical Schemes Turbulence
High Resolution
Gas - k- ε
Liquid - Laminar
Advection scheme
Upwind
Numerical Method
Finite Volume
Convergence Criteria
< RMS = 1 x 10-4
METHODOLOGY MODELING
• Density, dynamic viscosity and mass transfer models are in accordance with the model described by Korsten and Hoffmann, 1996. This model is the most used by the reseachers nowadays. • The Kinect model is the one presented by Chowdhury, 2002.
GOALS
• Validate the simulation results by comparing them with the model by Chowdhury, 2002; • Study the influence of the fluid dynamics in the reactor performance (reactor pressure drop, conversion, liquid holdup and others); • Simulate a real industrial size hydrotreating reactor (or a reactor section); • Study new reactor prototypes.
GOALS MODEL VALIDATION - HYDRODESULFURIZATION
Conversion (%)
1
0,75
0,5
0,25 573
593
613
633
Temperature (K) Simulation
Experimental
Figure – Conversion of sulfur
653
GOALS MODEL VALIDATION - HYDRODESULFURIZATION
Top
Bottom
Figure – Molar concentration of sulfur along the reactor
GOALS MODEL VALIDATION - AROMATICS 1
1
0,5
0 573
593
613
633
653
Mono
Di
Di-Exp
0,6 0,4 0,2 0 -0,2
Temperature (K) -0,5
Conversion (%)
Conversion (%)
0,8
Mono-Exp
Figure – Conversion of Mono and Di aromatics
-0,4
573
593
613
633
653
Temperature (K) Poly
Poly-Exp
Figure – Conversion of Polyaromatics
GOALS MODEL VALIDATION – VOLUME FRACTION PROFILES
Top
Figure – Liquid volume fraction
Bottom
Top
Figure – Gas volume fraction
Bottom
GOALS FLUID DYNAMICS ANALYSIS 0,162 0,16
65
0,158 64
63 Full
62
Just HDS
61
Holdup
Pressure drop (Pa/m)
66
0,156
0,154 Full
0,152
Just HDS
0,15 0,148
60
0,146 300
320
340
360
380
Temperature (K) Figure – Pressure drop inside the reactor
300
350
Temperature (K) Figure – Holdup inside the reactor
CONCLUSIONS • Despite the implementation of many models, our case was able to achieve optimal convergence and reproduce real phenomena with great similarity. • The results obtained show that modeling is according to the real system. •
The observed deviations may indicate the representation of tracks that models are not representative.
NEXT STEPS
CONFIGURATIONS
Option 1
Option 2
Reactor top
Reactor top
Gas outlet
Liquid outlet
Reactor bottom
Reactor bottom
Liquid outlet
Gas inlet Figure 5 –Reactor isometric view Figure 6 –Two option of reactor configurations
NEXT STEPS
• Simulate a real HDT reactor or a section of it; • Others geometries to improve hydrotreating;
• If possible, develop equipment patents.
THANK YOU! OPEN FOR QUESTIONS
APPENDIX MODEL PARAMETERS – SOURCE: ANCHEYTA, 2011
APPENDIX MODEL PARAMETERS – SOURCE: CHOWDHURRY, 2002.
HDS
• 𝑟𝐻𝐷𝑆 =
𝑚1 𝑚2 𝐾𝐻𝐷𝑆 𝐶𝐴𝑟_𝑆 𝐶𝐻2 𝑘𝑚𝑜𝑙 − (1+𝑘𝑎𝑑 𝐶𝐻²𝑆 ) 𝐾𝑔𝑠 .𝑠
HDA ∗ 𝐿 ∗ 𝐿 • 𝑟𝑖 = 𝑘𝐻𝐷𝐴 𝐶 − 𝑘 𝐶 𝐻𝐷𝐴 𝑝− 𝑝 𝑖 𝑖
APPENDIX
0,1555 0,155 0,1545 0,154 0,1535 0,153 0,1525 0,152 0
500
1000
1500
Number of elements
0
500
1000
1500
Number of elements
Figure. Mesh independence
Pressure Drop (Pa/m)
86,1 86,05 86 85,95 85,9 85,85 85,8 85,75 85,7 85,65
Holdup
Conversão (%)
MESH INDEPENDENCE 62 61 60 59
58 57 56 0
500
1000
1500
Number of elements
