Abstract: Improving the energy efficiency of natural gas in large scale clean heating，is not only significant for energy
conservation and emission reduction，but also of good social and economic benefits. Taking practical cases in Beijing as an
example，the feasibility and adaptability of gas-fired lithium bromide/ammonia-water absorption heat pumps and PAVE
systems are analyzed based on local natural gas price. The results show that gas-fired lithium bromide absorption heat
pumps are economic with an installation capacity at 60% boiler load，but it is not recommended for the gas-fired boiler
plant with a total capacity ≤28 MW. In order to improve the project economy，small and medium-sized gas-fired boiler
plants are recommended to take the joint operation with gas-fired boilers + small gas-fired ammonia-water absorption heat
pumps/PAVE system. In the practical cases，different technical routes should be selected according to the scale of gas-fired
boiler plants，installation capacity of the heat pump，local climate conditions and gas prices，so as to ensure the project
economy. The optimized route for gas-fired ammonia-water absorption heat pump/PAVE system is also pointed out.

Key words: gas-fired ammonia-water absorption heat pump, gas-fired lithium bromide absorption heat pump, indirect heat exchange, direct heat exchange, PAVE system