Parametric Sensitivity Studies in a Commercial FCC Unit

Prabha K Dasila, Indranil Choudhury, Deoki Saraf, Sawaran Chopra, Ajay Dalai

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DOI: 10.4236/aces.2012.21017                

Abstract

A steady state model was developed for simulating the performance of an industrial fluid catalytic cracking (FCC) unit which was subsequently used in parametric sensitivity studies. The simulator includes kinetic models for the riser reactor and the regeneration systems. Mass and energy balances were performed for each of these sections and simulation results were compared with the plant data available in the literature. Model predictions were found to be in close agreement with the reported data. Finally this validated model was used for studying the effects of independent variables such as feed preheat temperature (T_feed) and feed flow rate (F_feed) on the unit performance at either fixed regenerated catalyst temp/regenerator temp (T_rgn) or constant reactor outlet temperature (ROT). The catalyst circulation rate (CCR) was automatically adjusted to keep the ROT constant with varying the independent variables feed preheat temperature while the air rate adjusted for keeping the regenerator temperature constant which consequences the dependency of both dependent and independent variables on the unit performance. The air flow rate to the regenerator was also an independent variable during the parametric sensitivity analysis and its effect on FCC performance was investigated at constant T_feed, F_feed and CCR. Combining all the sensitivity analysis, it has been found to increase gas oil conversion and product yields by 5 to 6 percent with decrease of say, 10 K, in the feed preheat temperature (T_feed) and corresponding increase in air rate (F_air) and catalyst circulation rate (F_rgc) at constant reactor outlet temperature (ROT) and regenerated catalyst temperature (T_rgc).

Keywords

Fluid Catalytic Cracking; Parametric Sensitivity Analysis; Kinetic Modeling of FCC Riser/Reactor; Regenerator Modeling

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	V. W. Weekman Jr. and D. M Nace, “A Model of Catalytic Cracking in Fixed, Moving and Fluid Bed Reactors,” Industrial and Engineering Chemistry Process Design and Development, Vol. 7, No. 1, 1968, pp. 90-95. doi:10.1021/i260025a018
[2]	V. W. Weekman Jr., “Kinetics and Dynamics of Catalytic Cracking Selectivity in Fixed Bed Reactors,” Industrial and Engineering Chemistry Process Design and Development, Vol. 8, No. 3, 1969, pp. 385-391. doi:10.1021/i260031a015
[3]	L. Lee, Y. Chen and T. Huang, “Four-Lump Kinetic Model for Fluid Catalytic Cracking Process,” Canadian Journal of Chemical Engineering, Vol. 67, No. 4, 1989, pp. 615-619. doi:10.1002/cjce.5450670414
[4]	I. Wang, “High Temperature Catalytic Cracking,” Ph. D. Dissertation, Fuels Engineering Department, University of Utah, Salt Lake City, 1974.
[5]	L. C. Yen, R. E. Wrench and A. S. Ong, “Reaction Kinetic Correlation Equation predicts Fluid Catalytic Cracking Coke Yields,” Oil & Gas Journal, Vol. 86, 1988, pp. 67-70.
[6]	M. A. Abul-Hamayel, “Kinetic Modeling of High—Severity Fluidized Catalytic Cracking,” Fuel, Vol. 82, No. 9, 2003, pp. 1113-1118. doi:10.1016/S0016-2361(03)00017-6
[7]	A. Gupta and D. S. Rao, “Model for the Performance of a Fluid Catalytic Cracking (FCC) Riser Reactor: Effect of Feed Atomization,” Chemical Engineering Science, Vol. 56, No. 15, 2001, pp. 4499-4503. doi:10.1016/S0009-2509(01)00122-1
[8]	H. Ali, S. Rohani and J. P. Corriou, “Modeling and Control of a Riser-Type Fluid Catalytic Cracking (FCC) Unit,” Transactions of the Institution of Chemical Engineers, Vol. 75, 1997, pp. 401-412. doi:10.1205/026387697523868
[9]	A. Blasetti and H. de Lasa, “FCC Riser Unit Operated in the Heat-Transfer Mode: Kinetic Modeling,” Industrial & Engineering Chemistry Research, Vol. 36, No. 8, 1997, pp. 3223-3229. doi:10.1021/ie950704v
[10]	J. J. Ancheyta, I. F. Lopez and R. E. Aguilar, “5-Lump Kinetic Model for Gas Oil Catalytic Cracking,” Applied Catalysis A: General, Vol. 177, No. 2, 1999, pp. 227-235. doi:10.1016/S0926-860X(98)00262-2
[11]	G. M. Bollas, A. A. Lappas, D. K. Iatridis and I. A. Vasalos, “Five-Lump Kinetic Model with Selective Catalyst Deactivation for the Prediction of the Cracking Process,” Catalysis Today, Vol. 127, No. 1, 2007, pp. 31-43. doi:10.1016/j.cattod.2007.02.037
[12]	J. J. Ancheyta, I. F. Lopez, R. E. Aguilar and M. I. Moreno, “A Strategy for Kinetic Parameter Estimation in the Fluid Catalytic Cracking Process,” Industrial & Engineering Chemistry Research, Vol. 36, No. 12, 1997, pp. 5170-5174. doi:10.1021/ie970271r
[13]	J. J. Ancheyta, l. F. Lopez and R. L. Aguilar, “Correlations for Predicting the Effect of Feedstock Properties on Catalytic Cracking Kinetic Parameters,” Industrial & Engineering Chemistry Research, Vol. 37, No. 12, 1998, pp. 4637-4640.
[14]	D. J. Dave and D. N. Saraf, “A Model Suitable for Rating and Optimization of Industrial FCC Units,” Indian Chemical Engineer, Section (A), Vol. 45, 2003, pp. 7-19.
[15]	J. Corella, “On the Modeling of the Kinetics of the Selective Deactivation of Catalysts. Application to the Fluidized Catalytic Cracking Process,” Industrial & Engineering Chemistry Research, Vol. 43, No. 15, 2004, pp. 4080- 4086. doi:10.1021/ie040033d
[16]	S. M. Jacob, B. Gross, S. E. Volts and V. W. Weekman Jr., “A Lumping and Reaction Scheme for Catalytic Cracking,” AIChE Journal, Vol. 22, No. 4, 1976, pp. 701-713. doi:10.1002/aic.690220412
[17]	B. Gross, S. M Jacob, D. M. Nace and S. E. Voltz, “Simulation of Catalytic Cracking Process,” US Patent 3960707, 1976.
[18]	S. H. Cerqueira, E. C. Biscaia Jr. and E. F. Sousa-Aguiar, “Mathematical Modeling and Simulation of Catalytic Cracking of Gas Oil in a Fixed Bed: Coke Formation,” Applied Catalysis A: General, Vol. 164, No. 1, 1997, pp. 35-45. doi:10.1016/S0926-860X(97)00155-5
[19]	R. C. Ellis, X. Li and J. B. Riggs, “Modeling and Optimization of a Model IV Fluidized Catalytic Cracking Unit,” AIChE Journal, Vol. 44, No. 9, 1998, pp. 2068-2079. doi:10.1002/aic.690440914
[20]	R. K. Gupta, V. Kumar and V. K. Srivastava, “Modeling and Simulation of Fluid Catalytic Cracking Unit,” Reviews in Chemical Engineering, Vol. 21, 2005, pp. 95-131. doi:10.1515/REVCE.2005.21.2.95
[21]	R. K. Gupta, V. Kumar and V. K. Srivastava, “A New Generic Approach for the Modeling of Fluid Catalytic Cracking (FCC) Riser Reactor,” Chemical Engineering Science, Vol. 62, No. 17, 2007, pp. 4510-4528. doi:10.1016/j.ces.2007.05.009
[22]	J. M. Arandes, M. J. Azkoiti, J. Bilbao, H. I. de Lasa, “Modeling FCC Units under Steady and Unsteady State Conditions,” Canadian Journal of Chemical Engineering, Vol. 78, 2000, pp. 111-123. doi:10.1002/cjce.5450780116
[23]	W. Fei, R. Xing, Z. Rujin, L. Guohua and J. Yong, “A Dispersion Model for Fluid Catalytic Cracking Riser and Downer Reactors,” Industrial & Engineering Chemistry Research, Vol. 36, No. 12, 1997, pp. 5049-5053. doi:10.1021/ie9702183
[24]	C. Wu, Y. Cheng and Y. Jin, “Understanding Riser and Downer Based Fluid Catalytic Cracking Processes by a Comprehensive Two-Dimensional Reactor Model,” Industrial & Engineering Chemistry Research, Vol. 48, No. 1, 2009, pp. 12-26. doi:10.1021/ie800168x
[25]	T. A. Berry, T. R. McKeen, T. S. Pugsley and A. K. Dalai, “Two Dimensional Reaction Engineering Model of the Riser Section of a Fluid Catalytic cracking Unit,” Industrial & Engineering Chemistry Research, Vol. 43, No. 18, 2004, pp. 5571-5581. doi:10.1021/ie0306877
[26]	E. Baudrez, G. J. Heynderickx and G. B. Marin, “Steadystate Simulation of Fluid Catalytic Cracking Riser Reactors Using a Decoupled Solution Method with Feedback of the Cracking Reactions on the Flow,” Chemical Engineering Research and Design, Vol. 88, No. 3, 2010, pp. 290-303. doi:10.1016/j.cherd.2009.05.003
[27]	X. Zhou, T. Chen, B. Yang, X. Jiang, H. Zhang and L. Wang, “Kinetic Model Considering Reactant Oriented Selective Deactivation for Secondary Reactions of Fluid Catalytic Cracking Gasoline,” Energy & Fuels, Vol. 25, No. 6, 2011, pp. 2427-2437. doi:10.1021/ef200316r
[28]	J. H. Lee, S. Kang, Y. Kim and S. Park, “New Approach for Kinetic Modeling of Catalytic Cracking of Paraffinic Naphtha,” Industrial & Engineering Chemistry Research, Vol. 50, No. 8, 2011, pp. 4264-4279. doi:10.1021/ie1014074
[29]	A. Arbel, Z. Haung, I. H. Rinard, R. Shinnar and A. V. Sapre, “Dynamic and Control of Fluidized Catalytic Crackers. 1. Modeling of the Current Generation of FCC’s,” Industrial & Engineering Chemistry Research, Vol. 34, No. 4, 1995, pp. 1228-1243. doi:10.1021/ie00043a027
[30]	R. B. Kasat, D. Kunzuru, D. N. Saraf and S. K. Gupta, “Multiobjective Optimization of Industrial FCC Units Using Elitist Non—Dominated Sorting Genetic Algorithm,” Industrial & Engineering Chemistry Research, Vol. 41, No. 19, 2002. pp. 4765-4776. doi:10.1021/ie020087s
[31]	Y. X. Sha, “Deactivation by Coke in Residuum Catalytic Cracking, Catalysts Deactivation,” In: J. B. Butt, Ed., Bartholomew, Elsevier, Amsterdam, 1991, pp. 327-331.
[32]	A. Voorhies Jr., “Carbon Formation in Catalytic Cracking,” Industrial & Engineering Chemistry, Vol. 37, No. 4, 1945, pp. 318-322.
[33]	A. S. Krishna and E. S. Parkin, “Modeling the Regenerator in Commercial Fluid Catalytic Cracking Units,” Chemical Engineering Progress, Vol. 81, 1985, pp. 57- 62.
[34]	H. I. De Lasa and J. R. Grace, “The Influence of the Freeboard Region in a Fluidized Bed Catalytic Cracking Regenerator,” AIChE Journal, Vol. 25, No. 6, 1979, pp. 984-991. doi:10.1002/aic.690250609
[35]	R. C. McFarlane, R. C. Reineman, J. F. Bartere and C. Georgakis, “Dynamic Simulator for a Model IV Fluid Catalytic Cracking Unit,” Computers & Chemical Engineering, Vol. 17, 1993, pp. 275-300.
[36]	R. B. Ewell and G. Gadmer, “Design Cat Crackers by Computer,” Hydrocarbon Processing, Vol. 4, 1978, pp. 125-134.
[37]	A. A. Avidan and R. Shinnar, “Development of Catalytic Cracking Technology. A Lesson in Chemical Reactor Design,” Industrial & Engineering Chemistry Research, Vol. 29, No. 6, 1990, pp. 931-942. doi:10.1021/ie00102a001