With the increase of ambient temperature and the improvement of building energy efficiency

the supply-water temperature of the first-class heating network has decreased from 120～140 ℃ to 80～100 ℃

while the pressure of the extracted heating steam from the intermediate-pressure cylinder is generally 0.3～0.5 MPa in a conventional combined heat and power(CHP) unit

which is much higher than the needed steam pressure(0.07～0.14 MPa) of the supply-water heater. On account of superfluous steam pressure

a large exergy loss occurs in the heating process

resulting in a low energy efficiency of the unit. A heating system with waste pressure utilization(WPU) was introduced in this paper. The extraction steam firstly flows into the WPU turbine and drives the WPU generator to produce electricity

and then enters the supply-water heater to heat the supply-water. On the basis of a typical 300 MW CHP unit

the thermal performance of the new heating configuration was analyzed and assessed. The results show that

compared with the conventional heating system

the exergy efficiency of the improved heating system increased by 16.9 percentage points

which reduced the unit's standard coal consumption rate by 19.12 g/(kW·h)

and raised the overall efficiency of the unit by 2.42 percentage points. The energy-saving benefits are significant.