In the combined system of low temperature economizer and air heater

the heater usually can not be put into operation after the low temperature economizer stopped running. To solve this problem

a separated system combing the low temperature economizer with the air heater was proposed. In this system

the low temperature economizer and the air heater are two independent systems

the air heater is heated by No.7 extraction steam

which reduces the quality of the air heater's heat source. At the same time

the spraying system absorbs the heat of part of the exhaust steam

which increases the coal saving capacity. Taking a 600 MW unit in Inner Mongolia as the example

economic analysis for the separated system

combined system and the conventional low temperature economizer system were carried out. The results show that

the energy conservation potential of the separated system was 1.46 g/(k W·h) and 0.46 g/(k W·h) higher than that of the pure low temperature economizer system and the combined system

respectively. For the separated system

the energy conservation potential was better at lower load. In the spraying system

the energy conservation potential was better at higher environmental temperature

but decreased at lower load.