Parametric Optimization for Power De-rate Reduction in Integrated Coal-fired Power Plant with CCS Retrofit

Abstract

Carbon capture and storage (CCS) has attracted worldwide attention as a near-term technology to decelerate global warming. Especially, post-combustion CO2 capture has an economic advantage by utilizing existing coal-fired power plants. Aqueous monoethanolamine (MEA) scrubbing is the most common post-combustion capture technology. However, the heat and energy requirements of solvent regeneration and CO2 liquefaction cause the decrease in net power output up to 30 % by steam extraction and energy consumption. This power de-rate is a major obstacle to implementing CCS. In this study, simulation-based parametric optimization of the operating conditions was performed to minimize the power de-rate. Post-combustion CO2 capture with aqueous MEA scrubbing and CO2 liquefaction integrated with a 550 MWe supercritical coal-fired power plant was simulated using Aspen Plus V7.3. The stripper operating pressure and liquid to gas ratio of CO2 capture process were selected as the manipulated variables based on the variable evaluation. Steam extracted from IP-LP crossover pipe and the first LP turbine were considered as possible heat sources respectively. As a result, power de-rate was reduced from 38.3% to 17.4% when operating at optimum conditions.