Regeneration of hydrocarbon conversion catalysts - using dense-phase riser-mixer zone preceding relatively dense phase fluidised bed coke combustor

摘要

In the regeneration of hydrocarbon conversion catalysts deactivated by coke deposition, the regeneration being carried out by coke burn-off facilitated by an O2-contg. regeneration gas in a relatively dense phase fluidised bed coke, combustor, the improvement consists of providing a riser/mixer zone (I) in which incoming deactivated catalyst is mixed with a portion of regeneration gas and a portion of regenerated catalyst split off the stream recycled from the regenerator to the conversion zone. (I) is operated in the dense phase and upstream of the relatively dense phase conventional coke combustor. The first portion of regeneration gas is passed into the dense phase and the last into the relatively dense phase; the mixing of deactivated catalyst, regenerated catalyst and regenerated gas being effected above the point of entry of regeneration gas into the dense phase. Used esp. with fluid catalytic cracking processes. Circulation of regenerated and spent catalyst through (I) improves the dispersion of spent catalyst throughout the regeneration zone and minimises the problems of poor catalyst distribution.