In order to solve the frequent tripping caused by steam over temperature after the start up of a unit and ignition of the boiler, combined with the field operation data, it is confirmed that excessive output of the burner under low load and the mismatching of heat absorption on different levels heating surface are the main reasons for the overheating of the steam.Accordingly, a comprehensive plan including burner, desuperheating water, furnace flue modification and furnace combustion adjustment is proposed.By adding a burner back leakage bypass, back leakage can be increased and nozzle output can be reduced. By using the secondary air swirl baffle and adjusting the flame shape, heat absorption capacity of the water wall can be improved.By implementing the furnace flue transformation and redistribution flue gas flow,the heat absorption of the superheater can be reduced.By replacing a largeaperture desuperheating water nozzle, the control of the steam temperature can be improved. After retrofit, startup of boiler is stable, and overtemperature shutdown is basically eliminated, and steam parameters of the boilers are basically reach the design value. Relevant experience can be used for reference by similar equipment in the future.
