A hot primary air heater(HPAH)technology was introduced,which uses the heater installed on the hot primary air duct to heat condensation water,so the steam extraction amount can be reduced to increase the turbine's work ability,thus to save the energy.Moreover,the combined application of the HPAH and low pressure economizer(LPE)was studied,and the its application in a 600 MW unit was designed and calculated.The results show that,the HPAH is suitable for units with large quantity of cool air,high exhaust tem...