Assessment of a membrane contactor process for pre-combustion CO2 capture by modelling and integrated process simulation

Abstract

A membrane contactor process for pre-combustion CO2 capture from shifted synthesis gas originated from IGCC power plant is assessed from the technical and economical point of views. The process is designed as pressure swing absorption and desorption in a closed loop. The design basis for process simulation were synthesis gas containing CO2 and H2 only, and the CO2 capture efficiency was fixed to 90%. The CO2 gas was absorbed in ionic liquid [bmim][TCM] inside a hydrophobic, porous hollow fibre membrane contactor. One-dimensional mathematical model of membrane contactor developed in MATLAB was integrated to the process simulation software (HYSYS) through Cape-Open simulation compiler. The energy evaluation of this process revealed that compressors are the most energy demanding process equipment. The specific energy requirement for this process is estimated 0.75 MJ/kg CO2. A parametric study was also performed to analyse the effect of CO2 concentration in feed gas and liquid to gas ratio. The capital cost investment and total operating costs of CO2 capture unit were also evaluated. The capital investment required for capturing 0.14 M ton CO2/year including CO2 compression is 47.4 M $, and the operating cost per year is 9.04 M $. The membrane absorber contributed about 39% to total investment cost. The specific cost of this capture unit is calculated to be 87 $/ton CO2.