Systems Analysis of Ionic Liquids for Post-combustion CO2 Capture at Coal-fired Power Plants

摘要

The main objective of this study is to investigate the feasibility and costs of ionic liquid (IL)-based CO2 capture systems at pulverized coal-fired (PC) power plants. The IL selected for this assessment is trihexyl-(tetradecyl)phosphonium 2-cyanopyrrolide ([P66614][2-CNpyr]), achieving a 1:1 and reversible chemical reaction between [2-CNpyr]~- and CO2. A multi-stage equilibrium-based modeling framework is established to simulate the adiabatic absorption process, whereas a single-stage flash drum in equilibrium is employed for the stripping process. The performance model is linked to an engineering-economic model that estimates the capital cost, annual operating and maintenance (O&M) costs, and total levelized annual cost. The technical and cost models are applied to estimate the cost of CO2 captured by an IL-based CCS system. The preliminary results show that for 90% CO2 capture, the capture cost would be higher than the U.S. Department of Energy's target at $40 per metric ton of CO2 captured for new generation technologies, mainly due to a large capital cost. However, current process designs are not yet optimized. Based on the cost of CO2 captured, the most cost-effective capture cost is found to be at a removal efficiency of about 85% for CO2.