Systems and Methods for the Separation of Propylene and Propane

Abstract

Embodiments of the present invention generally disclose membrane-based systems and methods for the separation of propylene and propane that overcome certain issues associated with prior art devices and take advantage of a temperature drop across the associated separation membrane.

1 . A system for the membrane-based separation of a propylene and propane feed stream comprising, in combination:
 a first heat exchanger adapted and configured to raise said feed stream's temperature to a temperature at or slightly above the dewpoint of propylene;   a pump adapted and configured to pressurize said feed stream to a pressure between about 400 psia and about 500 psia;   a first membrane, said first membrane having a selectivity for propylene of at least 6.5, a feed port, a residue port, and a non-permeate port, said first membrane feed port being in fluid communication with said pump; and,   a second membrane, said second membrane having a selectivity for propylene of at least 2.5, a feed port, a residue port, and a non-permeate port, said second membrane feed port being in fluid communication with said first membrane non-permeate port.   
     
     
         2 . The system of  claim 1 , wherein said first heat exchanger is positioned upstream of said first membrane. 
     
     
         3 . The system of  claim 1 , further comprising a second heat exchanger positioned downstream of said first membrane and upstream of said second membrane, said second heat exchanger being adapted and configured raise a temperature of non-permeate from said first membrane non-permeate port to at or slightly above the dewpoint of propylene.