Fluidized catalytic cracking process utilizing a high temperature reactor

Abstract

The simultaneous use of lift gas in a riser zone that, operates above 975.degree. F. (525.degree. C.) and directly transfers catalyst and hydrocarbons to a series of cyclone separators, the stripping of spent catalyst in a heated stripper zone for the recovery of additional hydrocarbon vapors, and the immediate quenching of a converted hydrocarbon feed upon leaving a cyclone separator raises the octane and product yield in an FCC process. The process uses the specific steps of passing regenerated catalyst particles into the lower section of a substantially vertical riser conversion zone at a temperature greater than 975.degree. F. and accelerating the particles up the riser by contact with a lift gas comprising C.sub.3 and lighter hydrocarbons to a velocity of at least 1.2 meters per second. A series of injection nozzles introduce the feed into the moving catalyst in an upper portion of the riser in an amount that will maintain an average temperature of at least 520.degree. C. in the riser. Average hydrocarbon residence time in the riser is between 0.5 to 5 seconds. In order to suppress further conversion and thermal cracking, the converted feed and catalyst can be mixed with a diluent and transferred directly to cyclone separators. A hot stripper zone volatilizes additional carbons absorbed on the surface of the catalyst separated by the cyclone separators. Converted feed hydrocarbons leaving the cyclone separators are immediately contacted with a quench liquid and quenched to a temperature below that at which thermal cracking can occur. The process of this invention can also use catalyst to provide heat input for the stripping zone and a hydrogen environment in the stripper to suppress condensation reactions which would reduce the product yield and increase the coke production in the process. Another variation of the process uses a superadjacent quench chamber that immediately receives separated product vapors directly from the cyclone separators.