The client was losing significant quantities of vinyl chloride monomer (VCM) from an existing recovery system. The customer wanted to increase VCM recovery for pollution control purposes, but the existing compressor had no spare capacity.
Feed gas containing VCM and air was sent to the membrane system. The VCM-enriched permeate from the membrane section was compressed in a liquid-ring compressor and cooled to liquefy the VCM. The noncondensable gases were mixed with the feed gas and returned to the membrane section, and the residue stream was sent to the incinerator. VCM recovery was more than 99%. The membrane system — including the original membranes — has been in operation since 1999.