Gas flow distribution and optimization at the bottom of catalytic cracking industrial regenerator
As one of the core equipment of the catalytic cracking unit of the refinery,the regenerator not only ensures catalyst reutilization but also maintains pressure and heat balance within the reaction-regeneration system.However,the main air distribution at the bottom of the regenerator will give rise to particle agglomeration,flow dead zone and other gas-solid mixed flow problems within the regenerator,which will directly affect the thermal balance and continuous and stable operation of the production unit.In this work,computational fluid dynamics(CFD)method is used to simulate and calculate the bottom area of a 0.5 Mt/a catalytic cracking accumulator.Based on the k-ω turbulence model,the gas phase flow state at the bottom of the existing industrial regenerator can be obtained,which will provide some guidance for the gas-solid distribution in the upper and middle regions.Through simulation calculations,it is shown that the radial distribution of gas phase velocity near the outlet of gas distribution is severely uneven.Based on the existing structure and operating conditions of the bottom of the industrial regenerator,improvements are made to improve the uneven radial distribution of gas velocity.The effects of different inlet velocities,inverted cone structures,and distribution plate aperture sizes on the uniformity of gas velocity distribution are studied.The results indicate that the main air flow rate has a significant impact on the radial uniformity of gas velocity.The height to diameter ratio of the inverted cone and the distance from the inverted cone to the gas distributor have little effect on the uniformity of the radial distribution of gas velocity.By increasing the aperture of the limited flow holes in the main air distributor,the uniformity of the radial distribution of gas phase velocity in the area above the distributor is improved,and for this regenerator device,the gas distributor aperture size of around 18 mm is the most suitable.
catalytic crackingregeneratorgas distributorinverted coneflow field
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