Methods and systems for processing a crude oil feedstock

Abstract

A method of processing a crude oil feedstock may include: separating the crude oil feedstock to produce: a first feed fraction comprising hydrocarbons having a boiling point of greater than 350° C., a second feed fraction comprising hydrocarbons having a boiling point of greater than or equal to 160° C. and less than or equal to 350° C., and a third feed fraction comprising hydrocarbons having a boiling point of less than 160° C.; cracking the first feed fraction in a first downflow reaction zone of a fluid catalytic cracking (FCC) unit; cracking the second feed fraction in a second downflow reaction zone of the FCC unit; fractionating an effluent from the FCC unit to produce an FCC mixed C4 stream; and processing the third feed fraction and saturated C4 hydrocarbons from the FCC mixed C4 stream in a cracking unit to produce light olefins.

What is claimed is: 
     
         1 . A method of processing a crude oil feedstock, the method comprising:
 separating the crude oil feedstock to produce:
 a first feed fraction comprising hydrocarbons having a boiling point of greater than 350° C.; 
 a second feed fraction comprising hydrocarbons having a boiling point of greater than or equal to 160° C. and less than or equal to 350° C.; and 
 a third feed fraction comprising hydrocarbons having a boiling point of less than 160° C.; 
   cracking the first feed fraction in a first downflow reaction zone of a fluid catalytic cracking unit;   cracking the second feed fraction in a second downflow reaction zone of the fluid catalytic cracking unit;   fractionating an effluent from the fluid catalytic cracking unit to produce an FCC mixed C4 stream comprising C4 hydrocarbons; and   processing the third feed fraction and saturated C4 hydrocarbons from the FCC mixed C4 stream in a mixed feed cracking zone of a mixed feed steam cracking unit to produce light olefins.   
     
     
         2 . The method of  claim 1 , further comprising processing the FCC mixed C4 stream to increase a concentration of the saturated C4 hydrocarbons in the FCC mixed C4 stream. 
     
     
         3 . The method of  claim 2 , further comprising separating methyl tert-butyl ether, 1-butene, or both from the saturated C4 hydrocarbons prior to processing the saturated C4 hydrocarbons in the mixed feed cracking zone. 
     
     
         4 . The method of  claim 1 , wherein fractionating the effluent from the fluid catalytic cracking unit further produces at least one of:
 an FCC gas stream comprising hydrogen gas, methane, ethane, ethylene or combinations thereof;   an FCC mixed C3 stream comprising propane, propylene, or combinations thereof;   an FCC naphtha stream comprising hydrocarbons having at least 5 carbons and a boiling point less than or equal to 180° C.;   an FCC light cycle oil stream comprising hydrocarbons having a boiling point of greater than 180° C. and less than or equal to 360° C.; or   an FCC heavy cycle oil stream comprising hydrocarbons having a boiling point of greater than 360° C.   
     
     
         5 . The method of  claim 1 , further comprising:
 fractionating the effluent from the fluid catalytic cracking unit to produce an FCC gas stream comprising hydrogen gas, methane, ethane, ethylene or combinations thereof; and   processing the ethane from the FCC gas stream in the mixed feed cracking zone.   
     
     
         6 . The method of  claim 5 , further comprising recovering hydrogen gas, methane, ethylene, or combinations thereof from the FCC gas stream. 
     
     
         7 . The method of  claim 1 , further comprising:
 fractionating the effluent from the fluid catalytic cracking unit to produce an FCC mixed C3 stream; and   processing propane from the FCC mixed C3 stream in the mixed feed cracking zone.   
     
     
         8 . The method of  claim 1 , further comprising:
 fractionating the effluent from the fluid catalytic cracking unit to produce an FCC naphtha stream comprising hydrocarbons having at least 5 carbons and a boiling point less than or equal to 180° C.;   hydrotreating the FCC naphtha stream to produce hydrotreated FCC naphtha; and   passing at least a portion of the hydrotreated FCC naphtha to the mixed feed cracking zone.   
     
     
         9 . The method of  claim 8 , further comprising:
 processing the hydrotreated FCC naphtha in an aromatics extraction complex for recovery of aromatic products and production of aromatics extraction raffinate; and   passing the aromatics extraction raffinate to the mixed feed stream cracking zone.   
     
     
         10 . The method of  claim 8 , further comprising recovering gasoline from the hydrotreated FCC naphtha. 
     
     
         11 . The method of  claim 1 , further comprising:
 fractionating the effluent from the fluid catalytic cracking unit to produce an FCC light cycle oil stream comprising hydrocarbons having a boiling point of greater than 180° C. and less than or equal to 360° C.; and   processing the FCC light cycle oil stream to produce diesel, naphtha, fuel oil, or combinations thereof.   
     
     
         12 . The method of  claim 1 , further comprising fractionating the effluent from the fluid catalytic cracking unit to produce an FCC heavy cycle oil stream having a boiling point of greater than 360° C.; and
 at least one of:
 passing the FCC heavy cycle oil from the FCC heavy cycle oil stream to the fluid catalytic cracking unit; and 
 processing FCC heavy cycle oil from the FCC heavy cycle oil stream to produce fuel oils. 
 
 
     
     
         13 . The method of  claim 1 , wherein at least one of:
 the second feed fraction is added directly to the fluid catalytic cracking unit   the first feed fraction is added directly to the fluid catalytic cracking unit; and   the third feed fraction is added directly to the mixed feed steam cracking unit.   
     
     
         14 . The method of  claim 1 , wherein the crude oil feedstock has an American Petroleum Institute gravity of greater than or equal to 15 degrees and less than or equal to 50 degrees. 
     
     
         15 . A system for processing a crude oil feedstock, the system comprising:
 a feed splitter operable to separate the crude oil feedstock into a first feed fraction, a second feed fraction, and a third feed fraction;   a dual downer reactor operable to receive the first feed fraction and the second feed fraction;   a first separation unit downstream of the dual downer reactor;   a processing unit operable to receive an FCC mixed C4 stream from the first separation unit; and   a mixed feed steam cracking unit operable to receive the third feed fraction and a product stream from the processing unit.   
     
     
         16 . The system of  claim 15 , further comprising a hydrotreating unit downstream of the first separation unit operable to receive a product stream from the first separation unit. 
     
     
         17 . The system of  claim 16 , further comprising an aromatics extraction complex fluidly connected to the hydrotreating unit. 
     
     
         18 . The system of  claim 17 , wherein the first separation unit is directly connected to the hydrotreating unit, and the hydrotreating unit is directly connected to the aromatics extraction complex. 
     
     
         19 . The system of  claim 15 , wherein at least one of:
 the dual downer reactor is directly connected to the first separation unit;   the first separation unit is directly connected to the processing unit; and   the processing unit is directly connected to the mixed feed steam cracking unit.   
     
     
         20 . The system of  claim 15 , further comprising a cold distillation unit fluidly connected to the first separation unit and the mixed feed steam cracking unit.