FCC process

Abstract

The present invention is a fluidized catalytic cracking process that incorporates a zoned riser reactor. The process provides an in-situ method for feed upgrading in a riser reactor. The process assists in the removal of undesirable contaminants, such as nitrogen, from FCC feedstocks.

1 . A process comprising: 
 (a) passing a vacuum resid having boiling range greater than about 565° C. (about 1050° F.) to a resid processing unit;    (b) separating a light resid fraction having boiling range between about 565° C. and about 650° C. (about 1200° F.) from the vacuum resid;    (c) combining the light resid fraction with a FCC feed;    (d) passing the combined FCC feed to a FCC unit configured to have a plurality of reaction zones;    (e) in the FCC unit: 
 (i) contacting a first portion of catalyst with a secondary feed in a first upstream zone, the secondary feed having a boiling range between about 25° C. and about 250° C.;  
 (ii) in a first primary feed conversion zone, contacting the combined feed comprising nitrogen contaminants with the first portion of catalyst passed from the first upstream zone, wherein the temperature in the first primary feed conversion zone is greater than about 450° C., thereby vaporizing a substantial portion of the combined feed;  
 (iii) passing the effluent from the first primary feed conversion zone to a secondary primary feed conversion zone and contacting the effluent from the first primary feed conversion zone with a second portion of catalyst under catalytic cracking conditions.  
   
     
     
         2 . The process according to    claim 1    wherein the resid process unit is a short-path distillation unit.  
     
     
         3 . The process according to    claim 1    wherein the secondary feed further comprises between about 2 and about 50 wt % steam based on the total weight of the secondary feed.  
     
     
         4 . The process according to    claim 1    wherein the catalyst to secondary feed weight ratio in the first upstream zone is between about 30:1 and about 150:1.  
     
     
         5 . The process according to    claim 1    wherein the residence time in the first upstream zone is between about 0.1 and 1 second.  
     
     
         6 . The process according to    claim 1    wherein the residence time in the first primary feed conversion zone is less than 2 seconds.  
     
     
         7 . The process according to    claim 1    wherein at least 50 wt. % of the primary feed is vaporized.  
     
     
         8 . The process according to    claim 1    wherein at least 80 wt. % of the primary feed is vaporized.  
     
     
         9 . The process according to    claim 1    wherein the residence time in the second primary feed conversion zone is less than 2 seconds.  
     
     
         10 . The process according to    claim 1    further comprising contacting a third portion of regenerated catalyst with a secondary FCC feed, the third portion of regenerated catalyst comprising a catalytic cracking catalyst, the secondary feed comprising steam and hydrocarbons boiling in the range of about 25° C. to about 250° C. and then passing the third portion of regenerated catalyst and partially converted secondary FCC feed to a third primary feed conversion zone.  
     
     
         11 . The process according to    claim 1    further comprising in the third primary feed conversion zone downstream from the second primary feed conversion zone, contacting the effluent of the second primary feed conversion zone with the third portion of regenerated catalyst wherein the residence time in the third primary feed conversion zone is between about 0.2 and about 1 second.  
     
     
         12 . The process according to    claim 11    wherein the weight ratio of the first portion of catalyst to the sum of the weights of the second and third portions of catalyst is between about 1:1 and about 1:2 and wherein the weight ratio of the second portion of catalyst to the third portion of catalyst is between about 1:2 and about 1:1  
     
     
         13 . A process comprising: 
 (a) passing a atmospheric pipe still bottoms stream to a vacuum pipe still;    (b) separating a vacuum gas oil having a boiling range between about 340° C. and about 565° C. from the bottoms stream, the remainder comprising a vacuum resid fraction;    (c) passing at least a portion of the vacuum resid fraction to a short-path distillation unit;    (d) in the short-path distillation unit, separating a lighter resid fraction having a boiling range between about 565° C. and about 650° C. (about 1200° F.);    (e) combining the lighter resid fraction with the vacuum gas oil to form a FCC feed;    (f) passing the FCC feed to a FCC unit configured to have a plurality of reaction zones;    (g) in the FCC unit: 
 (i) contacting a first portion of catalyst with a secondary feed in a first upstream zone, the secondary feed having a boiling range between about 25° C. and about 250° C.;  
 (ii) in a first primary feed conversion zone, contacting the FCC feed comprising nitrogen contaminants with the first portion of catalyst passed from the first upstream zone, wherein the temperature in the first primary feed conversion zone is greater than about 450° C., thereby vaporizing a substantial portion of the FCC feed;  
 (iii) passing the effluent from the first primary feed conversion zone to a secondary primary feed conversion zone and contacting the effluent from the first primary feed conversion zone with a second portion of catalyst under catalytic cracking conditions.  
   
     
     
         14 . The process according to    claim 13    wherein the resid process unit is a short-path distillation unit.  
     
     
         15 . The process according to    claim 13    wherein the secondary feed further comprises between about 2 and about 50 wt. % steam based on the total weight of the secondary feed.  
     
     
         16 . The process according to    claim 13    wherein the catalyst to secondary feed weight ratio in the first upstream zone is between about 30:1 and about 150:1.  
     
     
         17 . The process according to    claim 13    wherein the residence time in the first upstream zone is between about 0.1 and 1 second.  
     
     
         18 . The process according to    claim 13    wherein the residence time in the first primary feed conversion zone is less than 2 seconds.  
     
     
         19 . The process according to    claim 13    wherein at least 50 wt. % of the primary feed is vaporized.  
     
     
         20 . The process according to    claim 13    wherein at least 80 wt. % of the primary feed is vaporized.  
     
     
         21 . The process according to    claim 13    wherein the residence time in the second primary feed conversion zone is less than 2 seconds.  
     
     
         22 . The process according to    claim 13    further comprising contacting a third portion of regenerated catalyst with a secondary FCC feed, the third portion of regenerated catalyst comprising a catalytic cracking catalyst, the secondary feed comprising steam and hydrocarbons boiling in the range of about 25° C. to about 250° C. and then passing the third portion of regenerated catalyst and partially converted secondary FCC feed to a third primary feed conversion zone.  
     
     
         23 . The process according to    claim 13    further comprising in the third primary feed conversion zone downstream from the second primary feed conversion zone, contacting the effluent of the second primary feed conversion zone with the third portion of regenerated catalyst wherein the residence time in the third primary feed conversion zone is between about 0.2 and about 1 second.  
     
     
         24 . The process according to    claim 23    wherein the weight ratio of the first portion of catalyst to the sum of the weights of the second and third portions of catalyst is between about 1:1 and about 1:2 and wherein the weight ratio of the second portion of catalyst to the third portion of catalyst is between about 1:2 and about 1:1