The pressure sliding operation strategy of the carbon capture system integrated within a coal-fired power plant: Influence factors and energy saving potentials

Abstract

The integration of a carbon capture system is an effective way to reduce CO 2 emissions from coal-fired power plants, but the carbon capture system consumes much steam and power, which causes a high efficiency penalty. In this study, thermodynamic analyses were conducted on the coal-fired power plant integrated with carbon capture system under load cycling operation conditions. Results show that the exergy efficiency penalty increases with the decrease of power load ration, and the exergy efficiency of coal-fired power plant decreases by 8.29 and 10.02 % under 100 and 30 % load ratios with the integration of carbon capture system, respectively. The irreversibility of carbon capture system increases with the decrease of load ratio of coal-fired power plant. To enhance the performance of coal-fired power plant integrated with carbon capture system under load-cycling operation conditions, the pressure sliding operation strategy is proposed. The performance of the integrated system can be improved by increasing the absorber pressure when the load ratio is below 75 %. Moreover, decreasing the stripper pressure is beneficial to reduce the energy consumption. As a result, by pressure sliding strategy, the exergy efficiency is improved by 0.23, 0.31, 0.3, 0.37 % under 100 %, 75 %, 50 % and 30 % load ratios, respectively. • A new operation strategy of pressure sliding for carbon capture system is proposed. • The performance of CFCC under load cycling operation conditions was evaluated. • Influences of the operation pressure of key devices were quantitatively analyzed. • The exergy performance was increased by 0.3–0.37 % under low power load ratio.