In order to improve the energy utilization efficiency of high flexibility power generation system coupled with internal combustion engine and coal-fired unit

a new thermal system combined with the internal combustion engine and the coal-fired unit was proposed. By feeding the flue gas of internal combustion engine and the waste heat of cooling water into the thermal system of coal-fired generating unit

the coal consumption of coal-fired generating unit can be reduced. EBSILON software was used to model the composite system. Steam consumption rate and heat consumption rate of the coal-fired units were taken as evaluation indexes to analyze the thermal economy of the coal-fired unit under different composite schemes. The results show that

the heat consumption rate and steam consumption rate of the coal-fired unit can be significantly reduced by combining the waste heat of the internal combustion engine into the thermal system of the coal-fired unit. The closer the compound position of flue gas waste heat is to the boiler

the smaller the proportion of feed water and condensed water involved in flue gas heat exchange

and the lower the heat consumption rate and steam consumption rate of the unit. When one part of the flue gas waste heat is used to heat the high pressure heater feed water and the other part is used to heat the low pressure heater condensed water

more waste heat will be allocated to feed water

and the heat consumption rate and steam consumption rate of the unit wil decrease. After optimization

the heat consumption rate of the combustion engine and coal-fired unit combined thermal system can be reduced by 6.62% at most.