Optimization of CO2 concentration captured by membrane technology - Possibility of reduction in CO2 capture energy and cost -

Abstract

The influence of specific power requirements and the membrane area on the CO2 recovery ratio and the CO2 concentration is investigated for CO2 membrane separation from a pressurized gas stream. Three different membrane configurations of a simple single stage, a single stage with permeate recycle, and an ideal two-cascade are considered. A feed gas containing 40% H2 and 60% CO2 and having a total pressure of 2.5MPa is used. In the cases of a simple single stage and a single stage with permeate recycle, a higher CO2 recovery ratio leads to a larger membrane area and higher energy consumption for the gas recycle. In addition, a higher CO2 concentration needs a larger membrane area and considerable power. An ideal two-cascade reduces the compressor power requirement as compared to a single stage with permeate recycle; however, it increases the membrane area. A lower CO2 concentration in the recovered CO2 stream implies a smaller membrane area and lower power requirement in the CO2 capture from the pressurized gas stream.