On the basis of analysis on two kinds of waste heat utilization approaches

using the low-temperature flue gas waste heat to heat the condensate water and feed water by installing heat exchangers in the tail flue duct

and improving the quality of steam turbine exhaust and circulating water to supply heat for users by adopting absorption heat pumps

a novel waste heat utilization system for thermal power plants was proposed.In this system

the flue gas after the air preheater is regarded as the heat pump's driving heat source

thus the absorption heat pump can recover the heat of condensation and heat the heating hot water.In addition

in order to meet the heating requirements in extremely cold periods

the heat exchanger is installed after the economizer in the tail flue duct

in which the heating hot water from heat pump exit is heated by part of the flue gas extracted from outlet of the economizer.In this system

the low-temperature heat is recovered by the absorption heat pump

so that the exergy loss is reduced in the heat transfer process

the extraction steam from the steam turbine decreases and the output power increases.Furthermore

combined with a 330 MW heat supply unit

this novel system's energy-saving effect was analyzed and the results were compared with that of the conventional flue gas waste heat utilization system(conventional system I)and the conventional condensation heat heat pump system(conventional system2).The results show that

the annual standard coal consumption of the unit applying this novel system is 8 487.8tless than that applying the conventional system I

and the output power is 1.3%to 2.7% higher than that applying the conventional system II

which indicates the energy saving effect of this novel waste heat utilization system is remarkable.