Waste heat recovery of power plant with large scale serial absorption heat pumps

Large amount of waste heat is dissipated in industries, resulting in energy waste and environment pollution. Waste heat recovery with absorption heat pump is one of the attractive solutions. In this paper, we present the theoretical study and test of a power plant waste heat recovery system with large scale LiBr-water absorption heat pumps for district heating. Waste heat from steam condenser with temperature of ∼35 °C is recovered by the absorption heat pumps driven by steam with pressure of ∼0.25 MPa from the turbine. Heat output from the absorption heat pumps is used to preheat the return water of district heating network from ∼45 °C to ∼80 °C. The return water is further heated by the steam to ∼105 °C for heating supply. Large temperature lift of the return water is achieved by the serial absorption heat pumps. Theoretical analysis of the system is presented, showing advantages compared to the conventional absorption heat pump and original heating supply system. On-site test showed that COP of 1.77 and heating capacity of 63.57 MW were achieved by one serial absorption heat pump, with waste heat inlet/outlet temperature of 34.63/28.33 °C and return water inlet/outlet temperature of 45.94/81.34 °C.