For circulating fluidized bed(CFB) boiler firing low-grade fuel with high ash content

the high ash content can affect the ash balance in furnace

and then affecting combustion

heat transfer

erosion

and dust emission performance etc

of the CFB boiler.Starting from substance balance in the furnace of CFB boiler

a fully new conception of Combustible Circulation Ratio has been put forward

and being used to study the ash balance in furnace and verify the necessity of discharging circulated ash during the CFB boiler firing fuel with high ash content.Comined with field test of a 50 MW CFB boiler firing coal with high ash content

the influence of high ash content and discharge of circulated ash upon boiler operation has been studied.Based on this

a discharging system of circulated ash for a 50 MW boiler has been designed.