Operational Flexibility and Thermodynamic Performances of a Combined Heat and Power Plant Integrated With Carbon Capture System

Abstract The global energy mix is evolving to sustainable and low carbon, so carbon capture should be developed and applied for the decarbonization of coal-fired power plants. Many coal-fired power plants have been reformed to combined heat and power, which can bring significant energy saving and economic benefits. When the combined heat and power plant is integrated with post-combustion carbon capture system, the carbon capture system will consume much steam extracted from steam turbines, and the heat and power outputs of the power plant will be influenced. Therefore, operational flexibility and thermodynamic performances of a combined heat and power plant integrated with carbon capture system will be evaluated in this study. A 660MW subcritical power plant is analyzed as the reference case, and a large-scale carbon capture system is integrated. The carbon capture system is driven by the exhaust steam of the intermediate pressure cylinder. The off-design simulation model of the coal-fired power plant is developed and validated, and the Aspen Plus software is used to develop the model of the carbon capture system. The integrated system is optimized to decrease the energy consumption of the carbon capture system, Then, operational flexibility and thermodynamic performances of the integrated system is evaluated. Results show that the adjustable ranges of heat and power loads decrease due to the integration of CCS. The energy efficiency within the operation domain in dominated by the heat load, but power load has higher influence on the exergy efficiency than the heat load. The coal consumption rate for carbon capture system is about 0.09kg/kg.