Economic analysis of CO2 separation from coal-fired flue gas by chemical absorption and membrane absorption technologies in China
Two typical CO 2 chemical absorption processes using MEA and aqueous ammonia (AA) solutions to act as absorbents and one novel process using hollow fiber membrane contactors (HFMCs) to act as absorber and MEA as absorbent were analyzed in this study to find out what CO 2 capture process may be more suitable for China. An ultra supercritical PC power plant with 840-MWe-gross-output was selected as the reference case without CO 2 capture. Economic results show that when membrane price is set at
... B 50/m 2 and lifetime is 5 years, CAPEX of MEA, HFMC and AA cases are increased by about 90.12%, 85.4% and 68%, respectively, compared to reference case. And the corresponding cost of avoided is RMB 305.1/tCO 2 , RMB 266.45/tCO 2 and RMB 206.02/tCO 2 , respectively. The seemingly positive results imply that AA-based chemical absorption process should be the best for China nowadays. In addition, prospect of HFMC process in the future was also considered based on the increasing anxiety of NH 3 slip for AA process. If membrane price can be reduced to less than RMB 20/m 2 and new solvents with ~3 GJ/tCO 2 total regeneration heat requirement can be adopted in the future, HFMC may replace the AA-based method to capture CO 2 . Additionally, economic results also show that the development of new solvents only considering the reduction of heat of CO 2 absorption may be not sufficient in terms of the reduction of CO 2 avoided cost. That is because CO 2 avoided cost can only be reduced by about 8% even the heat of CO 2 absorption can be reduced by about 60%. Finally, effects of coal price, improvements of reference case and CO 2 capture system on the cost of CO 2 avoided were also investigated.