US 5,310,477 AGranted

FCC process with secondary dealkylation zone

AssigneeUop LLC

InventorDavid A. Lomas

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Abstract

FCC process uses an open reactor vessel to house cyclones or other separation devices that reduce the carry through of product gases with the catalyst into the reactor vessel to less than 10 wt. % so that the catalyst in the reactor vessel provides a secondary dealkylation zone. By using a highly efficient separation device to remove product from the catalyst, the environment in the reactor vessel receives a low volume of cracked hydrocarbons from the riser conversion zone and provides a convenient secondary reaction zone that receives a recycled heavy gasoline fraction separated from the riser product stream. Dealkylation in the secondary reaction zone provides additional light gasoline to satisfy T90 requirements.

Claims16

Dependent claims

A process for the fluidized catalytic cracking (FCC) of an FCC feedstock selected from the group consisting of gas oils and residual hydrocarbons and the production of low boiling end point gasoline, said process comprising:

(a) passing said FCC feedstock and regenerated catalyst particles to a reactor riser and transporting said catalyst and feedstock upwardly through said riser thereby converting said feedstock to a riser gaseous product stream and producing partially spent catalyst particles by the deposition of coke on said regenerated catalyst particles;
(b) discharging a mixture of partially spent catalyst particles and gaseous products from a discharge end of said riser directly into a separation zone and recovering at least 90 wt % of the riser gaseous products from said riser in said separation zone;
(c) withdrawing said recovered riser gaseous products from said separation zone through a first gas outlet;
(d) separating said riser gaseous products from said first outlet into a first product stream comprising light gasoline having an end boiling point at a first temperature in a range of 300.degree. F. to about 400.degree. F., a heavy gasoline feed comprising C.sub.9 aromatics and having an initial boiling point at about said first temperature and an end boiling point at a second temperature of above 400.degree. F., and a first cycle oil stream having an initial boiling point at about said second temperature;
(e) passing said partially spent catalyst and not more than 10 wt % of the reactor riser gaseous products from said separation zone into a reaction vessel, maintaining a dense bed of catalyst in said reaction vessel and contacting said heavy gasoline feed with said partially spent catalyst in said dense bed of said reaction vessel to dealkylate said C.sub.9 aromatics and produce a reactor vessel product stream comprising C.sub.7 and C.sub.8 aromatics;
(f) withdrawing at least 90 wt % of said reactor vessel product stream from said reactor vessel through a second outlet;
(g) passing spent catalyst from said reactor vessel into a regeneration zone and contacting said spent catalyst with a regeneration gas in said regeneration zone to combust coke from said catalyst particles and produce regenerated catalyst particles for transfer to said reactor riser;
and,
(h) separating said reactor vessel product stream to recover additional light gasoline product having an end boiling point below said second temperature.

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Dependencies are inferred from the claim text.

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Abstract

(a) passing said FCC feedstock and regenerated catalyst particles to a reactor riser and transporting said catalyst and feedstock upwardly through said riser thereby converting said feedstock to a riser gaseous product stream and producing partially spent catalyst particles by the deposition of coke on said regenerated catalyst particles;
(b) discharging a mixture of partially spent catalyst particles and gaseous products from a discharge end of said riser directly into a separation zone and recovering at least 90 wt % of the riser gaseous products from said riser in said separation zone;
(c) withdrawing said recovered riser gaseous products from said separation zone through a first gas outlet;
(d) separating said riser gaseous products from said first outlet into a first product stream comprising light gasoline having an end boiling point at a first temperature in a range of 300.degree. F. to about 400.degree. F., a heavy gasoline feed comprising C.sub.9 aromatics and having an initial boiling point at about said first temperature and an end boiling point at a second temperature of above 400.degree. F., and a first cycle oil stream having an initial boiling point at about said second temperature;
(e) passing said partially spent catalyst and not more than 10 wt % of the reactor riser gaseous products from said separation zone into a reaction vessel, maintaining a dense bed of catalyst in said reaction vessel and contacting said heavy gasoline feed with said partially spent catalyst in said dense bed of said reaction vessel to dealkylate said C.sub.9 aromatics and produce a reactor vessel product stream comprising C.sub.7 and C.sub.8 aromatics;
(f) withdrawing at least 90 wt % of said reactor vessel product stream from said reactor vessel through a second outlet;
(g) passing spent catalyst from said reactor vessel into a regeneration zone and contacting said spent catalyst with a regeneration gas in said regeneration zone to combust coke from said catalyst particles and produce regenerated catalyst particles for transfer to said reactor riser;
and,
(h) separating said reactor vessel product stream to recover additional light gasoline product having an end boiling point below said second temperature.

6 more elements