The phenomena of central barrel deformation and drop-out from cyclonic separator of 300 MW CFB boilers have occurred in operation of one power plant.It is believed from analysis that the main causes are:large magniture of temperature variation in the zone of central barrel in the cyclonic separator

and it is often situated in over-temperature operation condition

the repetitive hot expansion and cold contraction process make the brace of central barrel to be ruptured.For this

preventive measures have been put forward

i.e.finding out through combustion adjustment test the optimal proportioning ratio between primary air and secondary air for the 300 MW CFB boiler

strictly controlling the temperature rise in furnace

and the speed rate of increasing and decreasing load in the process of start-up and shutdown

after implementation

similar phenomenon has never occurred.