Patent ID: 7939702

Claim:
A process for increasing production of light olefinic hydrocarbons from hydrocarbon feedstock by catalytic cracking, the process comprising the steps of: (a) feeding paraffinic naphtha or kerosene and steam into a catalytic cracking furnace where the naphtha or kerosene is subjected to a catalytic cracking reaction in the presence of a catalyst; (b) regenerating the catalyst used in the catalytic cracking reaction by a continuous or periodic regeneration procedure and recycling the regenerated catalyst into the catalytic cracking furnace; (c) quenching, compressing and separating the product of the catalytic cracking reaction, to separate and recover each of hydrogen, methane and C2-C3 olefinic hydrocarbons, and to separate a stream containing C2-C3 paraffinic hydrocarbons and a stream containing C4+ hydrocarbons; (d) feeding the stream containing C2-C3 paraffinic hydrocarbons into a recycling furnace where it is converted to C2-C3 olefinic hydrocarbons by a thermal cracking reaction, and recycling the converted C2-C3 olefinic hydrocarbons to the quenching step (c); and (e) recycling C4-C5 hydrocarbons of the stream containing C4+ hydrocarbon to the catalytic cracking furnace wherein the recycled C4-C5 hydrocarbons are subjected to a catalytic cracking reaction in the presence of a catalyst; and (f) optionally recycling C6+ hydrocarbons of the stream containing C4+ hydrocarbon to the catalytic cracking furnace wherein the recycled C6+ hydrocarbons are subjected to a catalytic cracking reaction in the presence of a catalyst, wherein a yield of ethylene and propylene produced by the catalytic cracking reaction of the recycled C4-C5 hydrocarbons together with the thermal cracking reaction of the recycled C2-C3 paraffinic hydrocarbons is higher than the yield of ethylene and propylene produced by the catalytic cracking reaction of the naphtha and kerosene.