GB769818A - Processes and apparatus for the catalytic cracking of hydrocarbon oiis - Google Patents

Abstract

<PICT:0769818/III/1> In a process for the cracking of a hydrocarbon oil wherein fluidized catalyst is cycled through the reactor 1 and a regenerator 2, and the catalyst withdrawn from the reactor is stripped with a gas such as steam to remove volatile hydrocarbons, the stripper 3 is situated within the regenerator, the stripped catalyst flows through openings 14 directly into the regenerator, and the vapours from the stripper are passed via a valved-line 10 into the vapour space of the reactor. The invention renders unnecesary the use of a standpipe with a control valve between the stripper and the regenerator. The hydrocarbon oil to be cracked is passed into the reactor through line 4, together with regenerated catalyst which is drawn off from the regenerator via standpipe 5 and slide-valve 6. Spent catalyst flows from the fluidized catalyst bed in the reactor via a stand-pipe 7 into riser 8, through which it is transported in a dispersed phase into the stripper by means of steam injected through line 9. The riser 8 extends above the level b of the catalyst bed in the stripper; and the catalyst particles issuing from the top of the riser fall into this bed, which is kept in a fludized state by means of steam supplied at the bottom via lines not shown. By means of valve 11 in line 10, the pressure in the gaseous phase of the stripping space, and thus the catalyst-level in the stripper, can be kept constant in case the pressure in the reactor becomes higher or lower. Specification 718,578 is referred to.