Dynamic modeling and comprehensive analysis of direct air-cooling coal-fired power plant integrated with carbon capture for reliable, economic and flexible operation

Abstract

Coal-fired power plants with direct air-cooling condensers (DACC-CFPP) are water-saving, eco-friendly and thus widely installed in regions rich in coal but short of water. As such regions have better geological conditions for CO2 storage, retrofitting these plants with carbon capture techniques provides a cost-efficient way to reduce carbon emissions and retain dispatchable power. However, the integration of carbon capture poses significant challenges for CFPP and DACC. Therefore, this paper develops a plant-wide model of the 660MWe DACC-CFPP integrated with post-combustion carbon capture (PCC). A connection system, including a steam extraction valve, water spray and condensate returning, is designed, added to the Steam turbine-Feedwater heaters-Condenser system and modeled to reflect dynamic interactions between the DACC-CFPP and PCC. This model is then used to evaluate the reliability, economics and flexibility of the DACC-CFPP-PCC over wide operating conditions. Results show that the integration of PCC causes changes in steam flowrate, pressure and temperature within the turbine, creating reliability risks; brings 5%–10% extra exergy loss to the DACC-CFPP, but not necessarily economic losses; reduces the minimum power load by 44MWe and improve the ramping speed by 3.75MWe/min. This paper provides in-depth insights for decision-makers, designers, and operators to manage the DACC-CFPP-PCC plant.