Processes and apparatus for isomerizing hydrocarbons
Processes and apparatus for isomerizing hydrocarbons are provided. The process comprises isomerizing at least a portion of the hydrocarbon feed stream comprising at least one of C 4 to C 7 hydrocarbons in the presence of an isomerization catalyst and hydrogen under isomerization conditions to produce a isomerized stream. The isomerized stream is stabilized in a stabilizer to provide a stabilizer off-gas stream comprising chlorides and a liquid isomerate stream. At least a portion of the stabilizer off-gas stream is contacted with an exchange stream to provide an absorber overhead stream and absorber bottoms stream comprising chlorides. The absorber bottoms stream is passed to the isomerization reactor. The liquid isomerate stream is passed to a deisohexanizer column to provide an isomerate product and deisohexanizer side stream.
1. A process for isomerizing a hydrocarbon feed stream comprising at least one of C 4 to C 7 hydrocarbons, wherein the process comprises:
isomerizing a first portion of the hydrocarbon feed stream in the presence of an isomerization catalyst and hydrogen in an isomerization reactor under isomerization conditions to produce an isomerized stream;
stabilizing the isomerized stream in a stabilizer unit to provide a stabilizer off-gas stream comprising chlorides and a liquid isomerate stream;
cooling a second portion of the hydrocarbon feed stream to a temperature of about −40° F. to about 20° F. to provide a chilled hydrocarbon feed stream;
contacting a first portion of the stabilizer off-gas stream with the chilled hydrocarbon feed stream in an absorber column to provide an absorber overhead stream and an absorber bottoms stream comprising chlorides; and
passing the absorber bottoms stream to the isomerization reactor.
2. The process of claim 1 , wherein the second portion of the hydrocarbon feed stream is cooled to a temperature of about −10° F. to about 10° F. to provide the chilled hydrocarbon feed stream.
3. The process of claim 1 , wherein the second portion of the hydrocarbon feed stream is about 20to about 35 wt % of the hydrocarbon feed stream.
4. The process of claim 1 wherein a second portion of the stabilizer off-gas stream bypasses the absorber column.
5. The process of claim 4 , wherein the second portion of the stabilizer off-gas stream comprises about 10 to about 40% of the stabilizer off-gas stream.
6. The process of claim 1 further comprising passing the absorber overhead stream to an additional chiller to provide a condensed stream which is passed back to the absorber column and a net portion of the absorber overhead stream being passed to a scrubber.
7. The process of claim 1 , wherein the contacting takes place in the absorber column at an operating pressure of about 1103 to 2068 kPa (160 to 300 psig).
8. The process of claim 1 further comprising splitting the hydrocarbon feed stream to provide the first portion of the hydrocarbon feed stream and the second portion of the hydrocarbon feed stream.
9. The process of claim 8 , wherein the absorber bottoms stream is passed downstream of the splitting of the hydrocarbon feed stream.
10. The process of claim 1 further comprising recycling at least one of a portion of the absorber overhead stream and a portion of a second portion of the stabilizer off-gas stream to the isomerization reactor by passing through an eductor upstream of the isomerization reactor.
11. The process of claim 1 further comprising passing at least a portion of the absorber overhead stream and a second portion of the stabilizer off-gas stream to a spent catalyst in a catalytic reforming unit.
12. A process for isomerizing a hydrocarbon feed stream comprising at least one of C 4 to C 7 hydrocarbons, wherein the process comprises:
isomerizing at least a portion of the hydrocarbon feed stream in the presence of an isomerization catalyst and hydrogen in an isomerization reactor under isomerization conditions to produce an isomerized stream;
stabilizing the isomerized stream in a stabilizer unit to provide a stabilizer off-gas stream comprising chlorides and a liquid isomerate stream;
passing the liquid isomerate stream to a deisohexanizer column to provide an isomerate product and a deisohexanizer side draw stream;
contacting a first portion of the stabilizer off-gas stream with a first portion of the deisohexanizer side draw stream in an absorber column to provide an absorber overhead stream and an absorber bottoms stream comprising chlorides;
cooling the first portion of the deisohexanizer side draw stream to a temperature of about −40° C. to about −7° C. (−40° F. to about 20° F.) before passing the first portion of the deisohexanizer side draw stream to the absorber column for the contacting step; and
passing the absorber bottoms stream to the isomerization reactor.
13. The process of claim 12 further comprising passing a second portion of the deisohexanizer side draw stream to the isomerization reactor.
14. The process of claim 12 wherein a second portion of the stabilizer off-gas stream bypasses the absorber column.
15. The process of claim 14 , wherein the second portion of the stabilizer off-gas stream comprises about 10 to about 40% of the stabilizer off-gas stream.
16. The process of claim 12 further comprising passing the absorber overhead stream to an additional chiller to provide a condensed stream and passing the condensed stream back to the absorber column and a net portion of the absorber overhead stream being passed to a scrubber.
17. The process of claim 12 further comprising recycling at least one of a portion of the absorber overhead stream and a portion of a second portion of the stabilizer off-gas stream to the isomerization reactor by passing through an eductor upstream of the isomerization reactor.
18. The process of claim 12 further comprising passing at least a portion of the absorber overhead stream and a second portion of the stabilizer off-gas stream to a spent catalyst in a catalytic reforming unit.
19. The process of claim 12 , wherein the contacting takes place in the absorber column at an operating pressure of about 1103 kPa (about 160 psig) to about 2068 kPa (about 300 psig).
20. A process for isomerizing a hydrocarbon feed stream comprising at least one of C 4 to C 7 hydrocarbons, wherein the process comprises:
isomerizing at least a portion of the hydrocarbon feed stream in the presence of an isomerization catalyst and hydrogen in an isomerization reactor under isomerization conditions to produce an isomerized stream;
stabilizing the isomerized stream in a stabilizer unit to provide a stabilizer off-gas stream comprising chlorides and a liquid isomerate stream,
passing the liquid isomerate stream to a deisohexanizer column to provide an isomerate product and a deisohexanizer side draw stream;
contacting a first portion of the stabilizer off-gas stream with a first portion of the deisohexanizer side draw stream in an absorber column to provide an absorber overhead stream and an absorber bottoms stream comprising chlorides;
passing the absorber overhead stream to an additional chiller to provide a condensed stream which is passed back to the absorber column and a net portion of the absorber overhead stream which is passed to a scrubber; and
passing the absorber bottoms stream to the isomerization reactor.