Large temperature-difference central heating system

The invention relates to a central heating system with large temperature difference, which belongs to the energy field. The system comprises a steam turbine, a condenser, a steam absorption heat pump, a steam-water heat exchanger, a hot water absorption heat pump, a water-water heat exchanger as well as a connecting pipe and accessories. The invention is characterized in that the temperature difference of the heat net supply is large, and is about one time higher than the conventional heat net operation, thus the transmission capacity of the heat net is greatly increased, and at the same time, no heat preservation and thermal stress compensation problems exist as the backwater temperature of the heating is low, thereby reducing the investment of the backwater pipeline network and the whole pipeline network; the steam turbine is utilized to discharge steam and preheat the backwater of the large heat net, and circulating cooling water is utilized to be taken as the low level heat energy of the absorption heat pumps. The invention has the advantages that the residual heat produced in the electricity generating process of a power plant is recycled to the greatest extent as much as possible, the combination mode of the hot water absorption heat pump and the water-water heat exchanger is adopted at the end to heat the hot water of the secondary heat net supply, and the temperature difference of the supply-water and the backwater of the large heat net are increased, at the same time, the heat net does not need external energy to be the driving force.