The exhaust temperature of a 300 MW unit boiler was higher than the designed value.To enhance the security and economy of the unit operation

reason analysis was conducted.Decrease in heat absorption of horizontal low-temperature reheater and economizer was considered as the major factor

which resulted from serious ash deposition on final heating surfacing caused by poor soot blowing effect of the flue gas impulse soot blower.Thus

several measures were carried out

such as reducing the air leakage in dry residue machine

adjusting the burner injection angle

and transforming the flue gas impulse soot blower into steam soot blower.After improvement

the exhaust temperature dropped by 16 ℃

the boiler efficiency increased by 0.94%

and the coal consumption decreased by about 3.29 g/(kW·h).The safety and economy of the unit was significantly enhanced.