The utilization of high back-pressure heating of the direct air-cooling unit can not only reduce heating steam extraction to promote the power generation capacity

but also recycle steam exhaust waste heat to enhance the heating capacity of the unit. In order to discuss the operating characteristics of the air-cooling unit with high back-pressure heating and further enhance the energy saving potential of the unit

taking the 300 MW direct air-cooling unit as an example

the theoretical model of high back-pressure heating is established based on the theory of variable working conditions of the heating unit and matrix analysis method. The effect of the environmental temperature changes on the performance of high back-pressure heating unit is analyzed. The results indicate that increasing the back pressure can increase the heating capacity of the unit. The back pressure of the unit's optimal operation has a decreasing tendency with the rising of environmental temperature. When the high back-pressure heating unit is operated according to the optimal operation curve

the power generation is greater and energy saving effect is more significant. This study provides a theoretical basis for the economic operation of the unit during the heating period.