The influence of membrane CO2 separation on the efficiency of a coal-fired power plant

In this paper, the influence of membrane separation of CO2 from flue gases and the impacts of the whole CCS process (CO2 separation and compression) on the performance of a coal-fired power plant are studied. First, the effects of the characteristics of the membrane (selectivity and permeability) and the parameters of the process (feed and permeate pressure) on two indices, CO2 recovery rate and CO2 purity are analysed. Next, a method for determining the minimum power loss and efficiency loss of the power plant as a function of these calculated indices is described. Then, the power requirements and efficiency loss (up to 15.4 percentage points) because of the CCS installation are calculated. A method for reducing these losses through the integration of the CCS installation with the power plant is also proposed. The main aims of the integration are heat exchange between media and a decrease in the CO2 temperature before compression. Implementing this process can result in a significant reduction of the efficiency loss by 8 percentage points.