Process for separating co2 from co2 containing gas stream

Abstract

The invention relates to gas separation, particularly to a process for separating COfrom a COcontaining gas stream with varying COconcentration using a membrane-based separation system. The process for separating COcomprises: (i) feeding the COcontaining gas stream into a membrane-based separation system comprising one or more membrane stages in-line, each membrane stage producing a CO-depleted retentate stream and a rich COpermeate stream, and (ii) recycling a part of the CO-rich permeate stream from at least one membrane stage as a recycled stream, into a preceding feed stream of one or more membrane stages in the membrane-based separation system to adjust the COconcentration of the feed stream. The process could stabilize the COconcentration in the feed steam by recirculation of a fraction of the high purity COpermeate to the feed of the membrane system, which would result in a lower incremental auxiliary load than other options such as compression of the entire gas stream.