During the utilization of CO2/N2 gas separation membranes for postcombustion
capture, the most important problem is how to create the driving force
efficiently because the feed flue gas has only ambient pressure and a relatively low CO2
content. Multi-stage systems are necessary using feasible membranes in order to fulfill
the separation target, required by the following pipeline transport, and limited by the
storage capacity. The whole work was divided into two steps: energy consumption
analysis and capture cost analysis.
This book chapter describes mass and energy balances for single-stage and multi-stage
membrane systems used in coal-fired power plant. After the recirculation of flue gas
and variation of the feed gas compressor and vacuum pump on the permeate side, two
concepts were developed and optimized to achieve minimum energy consumption. In
order to evaluate different membrane capture concepts, a comparison with chemical
absorption process was carried out, considering different degrees of CO2 separation.
Furthermore, a cost model was developed to make further analysis of the optimized
concept in view of the tradeoff balance between material and energy consumption. The
correlation between the membrane parameters (selectivity, permeability) and capture
cost was investigated.
Keywords: CCS, post-combustion, gas separation membrane, multi-stage, energy
consumption, economic analysis.
