Process for separation of propylene from a liquefied petroleum gas stream

A process, comprising:

• passing a feed stream comprising LPG to a column to produce an overhead stream comprising propylene, a side draw stream comprising C3 and a product stream comprising C4, and flashing the overhead stream to produce a net gas stream and an overhead residual stream comprising propylene;
• passing the overhead residual stream back to the column and dividing the side draw stream to produce a first stream and a second stream;
• passing the first stream to a stripper to produce a stripper overhead stream comprising C3 and a stripper product stream comprising propane and passing the second stream to a membrane unit with the stripper overhead stream;
• and
• passing a retentate stream comprising propane from the membrane unit back to the stripper and passing a permeate stream from the membrane unit to produce a polymer grade propylene stream.

A process, comprising:

• passing a feed stream comprising LPG to a dividing wall column to produce a first overhead stream comprising C3, a side draw stream comprising propane and a product stream comprising C4, and flashing the overhead stream to produce a net gas stream and an overhead residual stream comprising propylene and propane;
• passing a first portion of the overhead residual stream back to the column and passing a second portion of the overhead residual stream to a membrane;
• passing a first portion of the side draw stream back to the column and passing the second portion of the side draw stream as a propane product;
• and
• passing a retentate stream comprising propane from the membrane unit back to the column and passing a permeate stream from the membrane unit to a compression and cooling unit to produce a polymer grade propylene stream.