Modeling and optimization of an integrated membrane – P/VSA separation process for CO2 removal from coal plant flue gas

Abstract

This work presents a mathematical framework for the simulation and optimization of an integrated membrane – Pressure/Vacuum Swing Adsorption (P/VSA) process for CO2 removal from coal plant flue gas. The integrated process includes a membrane module in the first stage and a P/VSA unit in the second stage and it is optimized to minimize energy requirement for 95% and 90% total CO2 purity and recovery, respectively. Three membrane specifications, with CO2/N2 selectivity of 75, 50 and 25, and two adsorbents, zeolite 13X and MOF UTSA-16, are examined. The configuration which includes a membrane module with a CO2/N2 selectivity of 75 followed by a P/VSA unit with a UTSA-16 adsorbent leads to a minimum energy demand of 163 kWh/tn CO2, which is lower than the energy requirements of competitive CO2 separation processes, such as a two-stage P/VSA and multi-stage membrane processes. In addition, lowering the CO2/N2 selectivity from 75 to 50, leads to a minimum energy requirement of 177 kWh/tn CO2, which is still competitive to the other CO2 capture technologies. Furthermore, a comparison between different operating temperatures demonstrates that although a higher temperature increases the total energy demand, it has no impact on the optimal operating conditions and separation efficiency.