Ten megawatt scale vapor compression heat pump for low temperature waste heat recovery: Onsite application research

In order to limit global warming of 1.5 °C before 2050, the heat pump with waste heat recovery has been acknowledged as an effective technical solution. In this paper, a new kind of centrifugal heat pump system is applied to recover the waste heat from a steel plant for district heating. Two centrifugal compressors with vapor injection and two-cycle parallel connected system configuration are adopted to achieve higher energy efficiency and larger heating capacity. From simulation, the COP is expected to be more than 6 with a temperature rise of above 30 °C. To validate the calculation results, a 10 MW scale (9.5 MW) centrifugal heat pump was installed and tested in Angang Lingshan steel plant of China. With the waste water inlet temperature of 32.5 °C and hot water outlet temperature of 62.5 °C, the tested COP and heating capacity were 6.67 and 9.67 MW, respectively. The heating capacity of the system was greater than the heating load under severe conditions. Environmental and economic analyses of the waste heat recovery system are presented, showing advantages compared to the conventional heating methods. The PER of megawatt compression heat pump is as high as 2.53 and the payback period of this waste heat recovery system is 1.66 years.