Energy analyses and process integration of coal-fired power plant with CO2 capture using sodium-based dry sorbents

Abstract

Post-combustion CO2 capture using sodium-based solid sorbents is viewed as a promising technology owing to its advantages of low cost, easy accessibility, and low desorption temperature. It is necessary to evaluate the efficiency penalty of coal-fired power plants (CFPPs) using sodium-based solid sorbents prior to industrial applications. In this study, a typical 300 MW CFPP, coupled with a sodium-based CO2 capture system, was established in Aspen Plus. The simulation results demonstrate that the gross efficiency penalty was 15.5% as a result of this process. The energy consumption for the CO2 capture process was 7.23 GJ/tCO2 without any heat recovery; substantially higher than that of typical Monoethanolamine (MEA)-based CCS technologies, which is in the range of 3.8 to 4.2 GJ/tCO2. By recovering the heat of the outlet gas and sorbents from the desorption reactor, the energy consumption was reduced to 4.04 GJ/tCO2, with a gross efficiency penalty of 8.55%. To recover low-level heat from the sorption reactor, an economical system was proposed, consisting of a CFPP with CO2 capture and a cogeneration unit with an absorption heat pump. The energy consumption was further reduced to 1.08 GJ/tCO2, and the net efficiency penalty of this economical system was 11.99%. This method may provide significant economic and application prospects for sodium-based CO2 capture technology.