Patent ID: 10201778

Abstract:
The invention relates to gas separation, particularly to a process for separating CO2 from a CO2 containing gas stream with varying CO2 concentration using a membrane-based separation system. The process for separating CO2 comprises: (i) feeding the CO2 containing gas stream into a membrane-based separation system comprising one or more membrane stages in-line, each membrane stage producing a CO2-depleted retentate stream and a rich CO2 permeate stream, and (ii) recycling a part of the CO2-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 CO2 concentration of the feed stream. The process could stabilize the CO2 concentration in the feed steam by recirculation of a fraction of the high purity CO2 permeate 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.