Exergy-based analysis of conventional coal-fired power plant retrofitted with oxy-fuel and post-combustion CO2 capture systems

Abstract

Capturing and sequestering CO2 from coal-fired power plant is being proposed as one of the key solutions for stabilizing greenhouse gas concentration in the atmosphere. Recently, absorbing system and oxy-fuel combustion technology have been proposed as attractive options for capturing CO2 in power generation systems utilizing hydrocarbon fuels. This study is focused on energy and exergy analysis to compare the oxy-fuel combustion and absorbing system from different points of view to make a better insight into the cases from different aspects. The results show that the post-combustion and oxy-fuel CO2 capture systems result in 10.5% and 9.1% decrease in exergy efficiency of the retrofitted plants, respectively, compared with the conventional coal-fired power plant (base case). Additionally, boiler is the major exergy destruction source in all investigated plants. Also, air separation unit and CO2 capture and storage system have the largest amount of exergy destruction among the additional components of retrofitted plant with oxy-fuel combustion and post-combustion CO2 capture systems, respectively.