Processes and apparatus for isomerizing hydrocarbons

A process for isomerizing a hydrocarbon feed stream comprising at least one of C4 to C7 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.

A process for isomerizing a hydrocarbon feed stream comprising at least one of C4 to C7 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.