Experimental study of large temperature lift heat pump (LTLHP) in CHP system

Combined heating and power (CHP) system is one of most promising ways for district heating, however, more than 20% of heat gained in the boiler is discharged to atmosphere directly by the cooling tower. A new absorption heat pump named LTLHP adopting the lithium bromide aqueous solution as working pair is invented for heat recovery at the thermal power plant, and its temperature difference between the evaporator and condenser could reach 50 °C without risk of crystallization. The concentration difference of lithium bromide solution is 3.58% for a satisfying COP (coefficient of performance) without the risk of crystallization, which is far lower than that of a conventional absorption heat pump. The LTLHP is also experimented at a thermal power plant with double 330 megawatt steam turbines. The mean COP could reach 1.51 during the whole heating period, and 9.5 × 10^6 kg of coal could be saved annually, and the index of coal consumption for heating at the thermal power plant could be reduced to 14.0 kg/GJ, which is far lower than that of a conventional thermal power plant (18.0 kg/GJ).