Thermodynamic, Operational, and Techno-economic Analysis of A Novel Coal-fired Cogeneration System Integrated with Heat Pumps

Waste heat recovery can improve both the efficiency and flexibility of coal-fired cogeneration systems. In this paper, a novel system integrated with heat pumps is proposed. The evaporator of absorption heat pump is used to reduce the temperature of the thermal network return water, which could increase the temperature rise range of electric heat pump. Based on the simulation in EBSILON professional, a comparative study of the two systems is conducted regarding the thermodynamic, operational and techno-economic performance. Result shows that: The maximum heat load of the novel system is increased by 164.46 MW, resulting in a 9.89% increment in the gross efficiency. And the corresponding standard coal consumption rate for the power generation is decreased by 35.78 g/kWh. Furthermore, when the heat load is 400 MW, the power load regulation ratio of the novel system is increased by 10.57%. As the heat load increasing from 200 MW to 500 MW, the minimum power load difference between the two system is increased from 28.00 MW to 100.18 MW. Techno-economic analysis indicates that the novel system can save 49.27 kilotons of the coal during the whole heating season, resulting in an annual net revenue of 49.09 million CNY and a dynamic payback period of 4.59 years. The research could provide technical references for energy saving and flexibility optimization of cogeneration systems.