Catalytic cracking of metal-contg. heavy oils - by FCC process with controlled combustion in regenerator

摘要

Cracking of feeds contg. 650 deg. F+ material with a Ramsbottom carbon value of at least 1% and a heavy metals content of at least 4 ppm (Ni equiv.) is carried out by passing a suspension of a cracking catalyst in the feed through a riser-type cracking zone at 900-1400 deg.F and 10-50 psia with a vapour residence time of 0.5-10 sec. to obtain a conversion per pass of 50-90% and a coke yield of 6-14 wt.% based on fresh feed. The amt. of coke deposited on the catalyst is 0.3-3 wt.%. The coke-contaminated catalyst is sepd. from the cracking prods., stripped to remove adsorbed hydrocarbons, and regenerated by burning off coke with an O2-contg. gas under conditions such that the coke content is reduced to 0.25 wt.% or less. The regenerated catalyst is then recycled to the cracking zone. The improvement comprises burning off at least the major amt. of coke in a regenerator in which the CO:CO2 molar ratio is maintained at 0.25 or more. In complete combustion in the regenerator helps to avoid overheating of the regenerated catalyst, thus preventing excessive heat transfer to the cracking zone (see also GB2063294).