The disasters occurred on boilers of ultra-supercritical 660 MW unit after combining the booster air fan and the induced draft fan into one in one power plant

such as leading to boiler trip

too low suction in furnace after boiler shutdown

resulting in deformation and tear of expansion joint connecting the induced draft fan and the electrostatic precipitator

etc.

have been analysed.For these

a test of suction variation in the furnace and effectiveness of automatic regulation for the induced draft fan after outfire of boiler should be carried out during the time of low load in debugging period has been put forward for the designed boiler of combining the booster air fan and the induced draft fan into one

and during the time of type-selection in design

selection of the air fans with too steep characteristic curves should be avoided.