Installing low temperature economizer is an effective and low-cost way to reduce the exhaust temperature.This paper investigated the energy saving effect of this method.Results show that

the higher temperature of the pumping and returning water

the better economic efficiency of the economizer.Scheme 1 which pumps water from outlet of NO.6 low pressure heater and returns it to the deaerator has the maximum generation efficiency

which is improved by 0.34 percent compared with the boiler without low temperature economizer.Scheme 2 pumps water from the outlet of NO.6 and NO.7 low pressure heater

and returning it to the deaerator through the low temperature economizer after mixing.Compared with Sheme1

it can save heating surface area of about 1 000 m2.And the coal consumption for generation reduced by about 2.2 g/(kWoh) compared to the boiler without low temperature economizer.Finally

the boiler revamped by Scheme 2 has a dramatic energy saving effect because the exhaust temperature is decreased by about 30 ℃

and the coal consumption for generation decreased by 1.6 g/(kW·h).