Reconfiguration of recirculation stream in upgrading heavy oil

Abstract

Methods for hydroprocessing heavy oil feedstocks are disclosed. A heavy oil feedstock, a hydrogen-containing gas, and a slurry catalyst are passed through a plurality of upflow reactors operating under hydrocracking conditions to convert at least a portion of the heavy oil feedstock to lower boiling hydrocarbons, forming upgraded products. At least a portion of the mixture comprising the upgraded products, unconverted heavy oil feedstock, the hydrogen-containing gas, and the slurry catalyst from an upflow reactor other than the first upflow reactor is sent back to at least one upstream upflow reactor as a recycled stream.

1 . A process for upgrading a heavy oil feedstock, the process employing a plurality of upflow reactors configured in series comprising a first upflow reactor and a last upflow reactor, the process comprising:
 combining a heavy oil feedstock, a hydrogen-containing gas, and a slurry catalyst in the first upflow reactor under hydrocracking conditions to convert at least a portion of the heavy oil feedstock to lower boiling hydrocarbons, forming upgraded products;   passing a mixture comprising the upgraded products, unconverted heavy oil feedstock, the hydrogen-containing gas, and the slurry catalyst sequentially through each subsequent upflow reactor, wherein each subsequent upflow reactor is maintained under hydrocracking conditions with additional hydrogen-containing gas to convert at least a portion of the heavy oil feedstock to lower boiling hydrocarbons, forming additional upgraded products;   recycling at least a portion of the mixture comprising the upgraded products, unconverted heavy oil feedstock, the hydrogen-containing gas, and the slurry catalyst from at least one upflow reactor other than the first upflow reactor mixture back to at least one upstream upflow reactor forming a recycled stream; and   passing a mixture comprising the upgraded products, unconverted heavy oil feedstock, the hydrogen-containing gas, and the slurry catalyst from the last upflow reactor to a separator, whereby the upgraded products are removed with the hydrogen-containing gas as an overhead stream, and the slurry catalyst and the unconverted heavy oil feedstock are removed as a non-volatile stream.   
     
     
         2 . The process of  claim 1 , wherein the process employs at least two upflow reactors configured in series. 
     
     
         3 . The process of  claim 1 , wherein liquid in the first upflow reactor is recirculated at a rate of from 3 to 15 times the rate of the heavy oil feedstock. 
     
     
         4 . The process of  claim 1 , wherein liquid in the first upflow reactor is recirculated at a rate of from 3 to 10 times the rate of the heavy oil feedstock. 
     
     
         5 . The process of  claim 1 , wherein the recycled stream from an upflow reactor other than the first upflow reactor is recirculated at a rate of from 3 to 15 the rate of the heavy oil feedstock. 
     
     
         6 . The process of  claim 1 , wherein the recycled stream from an upflow reactor other than the first upflow reactor is recirculated at a rate of from 3 to 10 the rate of the heavy oil feedstock. 
     
     
         7 . The process of  claim 1 , wherein the recycled stream comprises from 0.3 to 30 wt. % of slurry catalyst. 
     
     
         8 . The process of  claim 1 , wherein the heavy oil feedstock is selected from the group consisting of atmospheric residuum, vacuum residuum, tar from a solvent deasphalting unit, atmospheric gas oils, vacuum gas oils, deasphalted oils, olefins, oils derived from tar sands or bitumen, oils derived from coal, heavy crude oils, synthetic oils from Fischer-Tropsch processes, and oils derived from recycled wastes and polymers. 
     
     
         9 . The process of  claim 1 , wherein the slurry catalyst comprises catalyst particles having an average particle of from 1 to 20 microns. 
     
     
         10 . The process of  claim 1 , wherein the hydrocracking conditions include a temperature of from 392° F. to 842° F. (200° C. to 450° C.), a reactor pressure of from 1450 to 3626 psig (10 to 25 MPa), a liquid hourly space velocity of from 0.05 to 10 h −1 , and a hydrogen treat gas rate of from 300 to 10,000 SCF/bbl (53.4 to 1781 m 3 /m 3 ).