Patent ID: 6179993
Filing Date: 2001-01-30
Classification: C10G

Abstract:
A process for producing olefins from a residual feedstock, which process comprises converting the feedstock in a process unit comprised of:(i) a heating zone wherein heat transfer solids containing carbonaceous deposits thereon are received from a stripping zone and heated in the presence of an oxidizing gas;(ii) a vapor short contact time reaction zone containing a bed of fluidized solids comprised of heat transfer solids recycled from the heating zone; and(iii) a stripping zone through which solids having carbonaceous deposits thereon are passed from the reaction zone and wherein lower boiling additional hydrocarbons and volatiles are recovered with a stripping gas; which process comprises:(a) feeding the residual feedstock to said vapor short contact time reaction zone wherein (it) the residual feedstock contacts the fluidized heat transfer solids and catalytic component, which reaction zone is operated at a temperature from about 760.degree. C. to about 790.degree. C. and under conditions such that the solids residence time and the vapor residence time are independently controlled, which vapor residence time is less than about 0.5 seconds, and which solids residence time is from about 5 to about 60 seconds, thereby resulting in a material being deposited onto said solids, and a vaporized fraction containing olefinic products, which material is characterized as a combustible carbonaceous metal-containing material, and wherein steam is fed at a rate from about 0.2 to 0.5 lbs per lb. of residual feedstock;(b) separating the vaporized fraction from the solids;(c) separating an olefin-rich fraction from said vaporized fraction;(d) passing the separated solids to said stripping zone where they are contacted with a stripping gas, thereby removing any remaining volatile material therefrom;(e) passing the stripped solids to said heating zone where they are heated to an effective temperature that will maintain the operating temperature of the reaction zone; and(f) recycling heated solids from the heating zone to the reaction zone where they provide the heat of reaction and are contacted with fresh feedstock.