| 摘要 |
A continuous process for producing gasoline hydrocarbons by the catalytic cracking of heavier hydrocarbon oils, wherein a hydrocarbon charge stream containing fresh oil and recylcle oil is subjected to a fluidized contacting of catalyst particles in a reaction zone, hydrocarbon conversion products are separated from the contacted catalyst particles, separated catalyst particles containing a coke deposit are subjected to a fluidized contacting of a free oxygen-containing gas stream in a separate regeneration zone with formation of combustion gases, the combustion gases are separated from hot regenerated catalyst particles, separated hot regenerated catalyst particles with a reduced coke content are returned to the reaction zone and the temperature of the reaction zone and the time of contact of the hydrocarbon charge stream with the catalyst particles therein are adjusted to effect on the catalyst particles in the reaction zone a coke deposition which provides in the regeneration zone a regeneration temperature above 621 DEG C. while after-burning in the upper portion of the regeneration zone is controlled by regulation of the supply of the oxygen-containing gas stream, is characterized in that upon attaining a regeneration temperature above 621 DEG C. an increased conversion into C4 and heavier hydrocarbons boiling within the gasoline range, measured as liquid volume per cent of the fresh oil, is brought about by obtaining an increased net production of coke, measured as weight per cent of the fresh oil, by the steps of using an increased catalyst circulation rate as well as an increased value of at least one of the conditions of (1) proportion of heavy recycle oil to fresh oil in hydrocarbon charge stream; (2) temperature in the reaction zone; and (3) temperature difference between the reaction zone and the regeneration zone. "Increased" means increased with respect to prior Specification 971,966. In examples the temperature in the dense phase of the regenerator is between 629 DEG C. and 649 DEG C., the corresponding temperature in the reactor dense phase varying between 489 DEG C. and 502 DEG C. Overall conversions of up to 78 volume per cent are produced. Low pressures, less than 2.1 kg/cm.2 are used. |
