THE REDUCTION OF FCCU AFTERBURNING THROUGH PROCESS OPTIMIZATION AND REGENERATOR REVAMPING
Scientific paper
DOI:
https://doi.org/10.2298/CICEQ210430023EKeywords:
FCCU, regenerator, afterburning, e-cat, cyclones, revampingAbstract
Operating the fluid catalytic cracking unit (FCCU) in afterburning conditions can increase the regenerator temperatures above the metallurgical design leading to mechanical failures of the cyclones and plenum chamber. This paper presents the methodology applied in a commercial FCCU to investigate the afterburning causes and the technical solutions that can be implemented to reduce the afterburning. Thus, by evaluating the regenerator temperature profile, regenerator as-build design, and the internals mechanical status, it was concluded that the main cause of afterburning was the non-uniform distribution and mixing of air and catalyst. The industrial results showed that optimizing the catalyst bed level, stripping steam, reaction temperature, and equilibrium catalyst (e-cat) activity reduced the afterburning by 39%. Other process parameters such as feed preheat temperature, slurry recycling, and excess oxygen did not significantly influence afterburning because of air and catalyst maldistribution. Revamping the regenerator to assure a symmetrical layout of cyclones reduced the afterburning by 86%, increased the fines retention in FCCU inventory, and provided a better regeneration of the spent e-cat. The reduction of operating temperatures at around 701°C removed the risk of catalyst thermal deactivation, and therefore the e-cat activity was increased by 10.2 wt.%.
References
P. Bai, U.J. Etim, Z. Yan, S. Mintova, Z. Zhang, Z. Zhong, X. Gao, Catal. Rev. 61 (2018) 335 – 405.
G.J. García, R.A. López, R.M. Yescas, Fuel 90 (2011) 3531 – 6541.
M. Clough, J.C. Popea, L. Tan, X. Lin, V. Komvokis, S. S. Pan, B. Yilmaz, Microporous Mesoporous Mater. 254 (2017) 45 – 58.
R. Sadeghbeigi, Fluid Catalytic Cracking Handbook (Third Edition), Elsevier Inc, Oxford (2012), 117 – 262.
J.A. Sexton, in Advances in Fluid Catalytic Cracking: testing, characterization and environmental regulations, M.L Occeli, CRC Press, Boca Raton (2010) 271 – 289.
R. Fletcher, M. Evans, Intercat (Johnson Matthey), Revamps PTQ (2010) 3 – 15. https://cdn.digitalrefining.com/data/digital_magazines/file/1420275728.pdf [accessed 25 May 2021].
J.R. Wilcox, in Advances in Fluid Catalytic Cracking: testing, characterization and environmental regulations, M.L. Occeli,
CRC Press, Boca Raton (2010) 101 – 118.
A.W. Chester, in Fluid Catalytic Cracking VII - Materials, Methods and Process Innovations; Studies in Surface Science and Catalysis, Vol. 166, M.L. Occelli, Elsevier, Amsterdam (2007) 67 – 77.
G. Davison, Guide to Fluid Catalytic Cracking, Part Two, W.R. Grace & Co.-Conn, J.W. Boarman Co. Baltimore, Maryland (1996) 155-156.
G. Davison, Guide to Fluid Catalytic Cracking, Part Three, W.R. Grace & Co.-Conn, J.W. Boarman Co. Baltimore, Maryland (1999) 255-284.
J. W. Wilson, FCC Regenerator Afterburn Causes and Cures, Wilson P.E., Barns and Click, Inc., AFPM Annual Meeting (2003) AM-03-44.
R. Butterfield, T. Ventham, P. Diddams, M. Evans, Hydrocarbon Engineering 22 (2017) 55-60.
F. Rosser, M. Schnaith, P.W. Walker, Integrated View to Understanding the FCC NOx Puzzle, AIChE Symposium, Austin, Texas (2004).
Z. Yang, Y. Zhang, T. Liu, O. Adefarati, Chemical Engineering Journal 421 (2021) 129694.
Z. Yang, Y. Zhang, O. Adefarati, J. Yue, Chemical Engineering Journal 412 (2021) 128634.
Y. Zhang, Baffles and Aids to Fluidization (Chapter 18), Essentials of Fluidization Technology, G. John, B. Xiaotao, E. Naoko (eds.). Wiley-VCH (2020) 431-455.
R. Fletcher, S. Clark, P. Blaser, Identifying the Root Cause of Afterburn in Fluidized Catalytic Crackers. AFPM Annual Meeting (2016) AM-16-15.
Y.M. Chen, Evolution of FCC - Past Present and Future and The Challenges of Operating a High Temperature CFB System, 10th International Conference on Circulating Fluidized Beds and Fluidization Technology - CFB-10, T. Knowlton, PSRI Eds., ECI Symposium Series (2013).
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Copyright (c) 2022 Florin Enache , Dan Dănulescu , Ion Bolocan , Diana Cursaru
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