The conventional central heating by cogeneration uses extraction steam from intermediate pressure cylinder to heat the circulating water in thermal network

but this will cause great irreversible heat loss due to the large heat exchange temperature difference. To solve this problem

low-grade energy heating technology is put forward

which directly recycles the steam exhaust from steam turbine and heats the circulating water in thermal network. The circulating water which has absorbed the heat in thermal network is further heated by extraction steam from the intermediate pressure cylinder

and this realizes more efficient and comprehensive use of steam energy. Taking the air-cooling heating units in Taiyuan Jiajie Gas Thermal Power Plant as an example

by using the low-grade energy heating technology

the heating system was retrofitted. After optimization

the heating area expanded by 2×10~6 m~2

the heating amount increased by 9.260×10~5 GJ

and the generating capacity in the entire heating season increased by 6.957×10~7 k W·h. The run and performance test of 168 h demonstrates that the retrofitted heating system works stably and meet the actual running needs. The application of low-energy heating technology enhances the efficiency of thermal conversion of the units

expands the heating area and reduces the heating costs of thermal power plant

which gives certain guidance to units of similar types.