Simulation and comprehensive study of an optimum process for CO2 capture from flue gas; technical, economic, and environmental analyses

Abstract

An optimum process with a novel method for improving the thermodynamic efficiency of the conventional post-combustion process based on a mono-ethanolamine (MEA) 30 wt% solvent is presented. The presented process, by preheating the rich solvent stream twice and using lean vapor compression (LVC), causes the solvent regeneration energy (Eregen) to decrease, the exergy efficiency of the desorption column to increase, and the net CO2 emission to diminish. According to the simulation results, the solvent regeneration energy in the base process is 3.47 GJ/tCO2 and has a value of 2.77 GJ/tCO2 in the proposed scheme, which exhibits a 20.17% decrease. The exergy analysis showed that the desorption column contributes the most to the exergy destruction in the post-combustion process. According to the performed analysis, in the proposed scheme, the exergy destruction in the desorption column reduces from 476.67 kW to 257.48 kW, which shows a 45.98% decrease. Under these conditions, the exergy efficiency of the desorption column is improved by 12.2%. Comparing Eregen parameter with that of previous studies demonstrated that the proposed scheme in this paper has significant superiority regarding optimizing the reboiler's energy. Due to the addition of a compressor, heat exchanger, expansion valve, and separator, the annual capital expenditure (CAPEXy) of the proposed scheme is 13.71% higher than the conventional process, which results in a 12.5% increase in the cost of CO2 capture (CostCO2,capture).