GB801656A - Process for the staged catalytic cracking of hydrocarbon oils using finely divided solid catalyst - Google Patents

Abstract

<PICT:0801656/III/1> In a two-stage process for cracking a hydrocarbon oil using finely-divided solid catalyst, wherein hot freshly-regenerated catalyst is used to crack the oil in the first cracking zone A, the partially-spent catalyst withdrawn from A being stripped with a gas such as steam in a stripper B and then passed into the second cracking zone C where it cracks a fraction, heavier than gasoline, separated in a fractionating column D from the products obtained from A, the vapours withdrawn from stripper B are passed through line 9 into the fractionating column E used for separating the products obtained in C. In the Figure, the vapours from stripper B are first mixed with the cracked products from zone C and then introduced into column E, but it is also possible to introduce these two streams separately into the column at two different points. Stripper B is preferably of small diameter, and the partially-spent catalyst is carried through it in suspension in the stripping gas; the suspension is then separated by settling or centrifugal action. The spent catalyst withdrawn from the second cracking zone C is stripped with steam in stripper F, the vapour effluent from which is either passed through line 14 into column E, or it is passed through line 15 for use as the stripping medium in stripper B. The stripped catalyst withdrawn from stripper F through line 16 is regenerated with air in regenerator G; and the hot regenerated catalyst is passed through line 19 to be mixed with fresh feed. Gasoline (+ gas) is withdrawn from the system through lines 6 and 10. The higher-boiling oil withdrawn from column E through line 12 is recycled to cracking zone C. Specification 784,546 is referred to.