Flexible operation of oligomerization process

Abstract

A process and apparatus for controlling the amount of gasoline and distillate obtained from an oligomerate product is described. The process includes oligomerizing olefins in a feed stream to produce a mixture of an oligomerate product and unreacted feed. The mixture is separated into a light stream comprising the unreacted feed and the oligomerate product. Some or all of the oligomerate product is hydrogenated to produce hydrotreated oligomerate product. The hydrotreated oligomerate product can be separated into gasoline and distillate. A recycle stream comprising at least one of non-hydrotreated oligomerate product and hydrotreated oligomerate product is introduced into the oligomerization zone. The flow rates of non-hydrotreated oligomerate product and hydrotreated oligomerate product in the recycle stream are controlled to control the amount of gasoline and distillate product produced.

What is claimed: 
     
         1 . A process for controlling an amount of gasoline and distillate obtained from an oligomerate product comprising:
 introducing an oligomerization feed stream comprising at least one of C4 or C5 olefins into an oligomerization zone under oligomerization conditions in the presence of an oligomerization catalyst to oligomerize olefins in the oligomerization feed stream in liquid phase to produce a mixture of an oligomerate product comprising C5+ hydrocarbons and unreacted C4 or C5 feed olefins; and   separating the mixture into a light stream comprising the unreacted C4 or C5 feed olefins and a stream of the oligomerate product in a first separation zone;   optionally dividing the stream of oligomerate product into a first portion and a second portion, the first portion being a non-hydrotreated oligomerate product;   hydrogenating at least the second portion of the stream of the oligomerate product to produce a stream of hydrotreated oligomerate product;   introducing a recycle stream into the oligomerization zone, the recycle stream comprising at least one of the optional first portion of non-hydrotreated oligomerate product and a recycle portion of the stream of hydrotreated oligomerate product; and   controlling a flow rate of the optional first portion of non-hydrotreated oligomerate product and a flow rate of the recycle portion of the stream of hydrotreated oligomerate product in the recycle stream to control the amount of gasoline and distillate product produced.   
     
     
         2 . The process of  claim 1  wherein the optional first portion of non-hydrotreated oligomerate product is present and wherein controlling the flow rate of the first optional portion of non-hydrotreated oligomerate product and the flow rate of the portion of the stream of hydrotreated oligomerate product in the recycle stream comprises increasing the flow rate of the portion of the hydrotreated oligomerate product in the recycle stream to increase the amount of the gasoline product produced. 
     
     
         3 . The process of  claim 1  wherein the optional first portion of non-hydrotreated oligomerate product is present and wherein controlling the flow rate of the first optional portion of non-hydrotreated oligomerate product and the flow rate of the portion of the hydrotreated oligomerate product in the recycle stream comprises increasing the flow rate of the first portion of non-hydrotreated oligomerate product in the recycle stream to increase the amount of the distillate product produced. 
     
     
         4 . The process of  claim 1  wherein the recycle stream comprises at least about 50 wt % of hydrotreated oligomerate product and less than about 50 wt % of non-hydrotreated oligomerate product. 
     
     
         5 . The process of  claim 1  wherein the recycle stream comprises at least about 90 wt % of hydrotreated oligomerate product and less than about 10 wt % of non-hydrotreated oligomerate product. 
     
     
         6 . The process of  claim 1  wherein the recycle stream comprises at least about 90 wt % of non-hydrotreated oligomerate product and less than 10 wt % of hydrotreated oligomerate product. 
     
     
         7 . The process of  claim 1  wherein the oligomerization conditions include an operating temperature in a range of about 160° C. to about 260° C. and a pressure in a range of about 2.1 MPa (g) to about 10.5 MPa (g). 
     
     
         8 . The process of  claim 1  wherein the oligomerization catalyst comprises a zeolite with a framework having a ten-ring pore structure. 
     
     
         9 . The process of  claim 8  wherein the oligomerization catalyst comprises a zeolite having a uni-dimensional, ten-ring pore structure. 
     
     
         10 . The process of  claim 9  wherein the oligomerization catalyst comprises an MTT zeolite. 
     
     
         11 . The process of  claim 1  wherein the oligomerization feed stream is obtained by:
 cracking a hydrocarbon feed over an FCC catalyst in an FCC zone to produce spent FCC catalyst and a cracked product stream; and 
 obtaining the oligomerization feed stream from the cracked product stream. 
 
     
     
         12 . A process for controlling an amount of gasoline and distillate obtained from an oligomerization product comprising:
 cracking a hydrocarbon feed over an FCC catalyst in an FCC zone to produce spent FCC catalyst and a cracked product stream;   obtaining an oligomerization feed stream comprising at least one of C4 or C5 olefins from the cracked product stream;   introducing the oligomerization feed stream into an oligomerization zone under oligomerization conditions in the presence of an oligomerization catalyst to oligomerize olefins in the oligomerization feed stream in liquid phase to produce a mixture of an oligomerate product comprising C5+ hydrocarbons and unreacted C4 or C5 feed olefins;   separating the mixture into a light stream comprising the unreacted C4 or C5 olefins and a stream of oligomerate product in a first separation zone;   optionally dividing the stream of oligomerate product into a first portion and a second portion, the first portion being a non-hydrotreated oligomerate product;   hydrogenating at least the second portion of the stream of oligomerate product to produce a stream of hydrotreated oligomerate product; dividing the stream of hydrotreated oligomerate into a product portion and a recycle portion;   separating a product portion of the stream of hydrotreated oligomerate product into a stream of gasoline and a stream of distillate in a second separation zone;   introducing a recycle stream into the oligomerization zone, the recycle stream comprising at least one of the of the optional first portion of non-hydrotreated oligomerate product and the recycle portion of the hydrotreated oligomerate product; and   controlling a flow rate of the optional first portion of the non-hydrotreated stream of oligomerate product and a flow rate of the recycle portion of the hydrotreated oligomerate product in the recycle stream to control the amount of gasoline and distillate produced;   wherein controlling the flow rate of the optional first portion of the non-hydrotreated oligomerate product and the flow rate of the recycle portion of the hydrotreated oligomerate product in the recycle stream comprises increasing the flow rate of the recycle portion of the hydrotreated oligomerate product in the recycle stream to increase the amount of gasoline product produced or increasing the flow rate of the optional first portion of the non-hydrotreated oligomerate product in the recycle stream to increase the amount of distillate product produced.   
     
     
         13 . The process of  claim 12  wherein the recycle stream comprises at least about 50 wt % of hydrotreated oligomerate product and less than about 50 wt % of non-hydrotreated oligomerate product. 
     
     
         14 . The process of  claim 12  wherein the recycle stream comprises at least about 90 wt % of hydrotreated oligomerate product and less than about 10 wt % of non-hydrotreated oligomerate product. 
     
     
         15 . The process of  claim 12  wherein the recycle stream comprises at least about 90 wt % of the non-hydrotreated stream of oligomerate product and less than about 10 wt % of hydrotreated oligomerate product. 
     
     
         16 . The process of  claim 12  wherein the oligomerization conditions include an operating temperature in a range of about 160° C. to about 260° C. 
     
     
         17 . The process of  claim 12  wherein the oligomerization catalyst comprises a zeolite with a framework having a ten-ring pore structure. 
     
     
         18 . The process of  claim 12  wherein the oligomerization catalyst comprises a zeolite having a uni-dimensional, ten-ring pore structure. 
     
     
         19 . The process of  claim 12  wherein the oligomerization catalyst comprises an MTT zeolite. 
     
     
         20 . An apparatus for controlling the production of diesel and gasoline comprising:
 an oligomerization reaction zone with an inlet and an outlet;   a first separation zone with an inlet, an overhead outlet, and a bottoms outlet; the inlet of the separation zone being in fluid communication with the outlet of the oligomerization zone;   a hydrogenation zone having an inlet and an outlet, the inlet of the hydrogenation zone being in fluid communication with the bottoms outlet of the separation zone;   a second separation zone with an inlet, an overhead outlet, and a bottoms outlet, the inlet of the second separation zone being in fluid communication with the outlet of the hydrogenation zone;   the bottoms outlet of the first separation zone being in fluid communication with the inlet of the oligomerization zone and the outlet of the hydrogenation zone being in fluid communication with the inlet of the oligomerization zone; and   a controller for controlling a flow from the bottoms outlet of the first separation zone to the inlet of the oligomerization zone and a flow from the outlet of the hydrogenation zone to the inlet of the oligomerization zone.