During low bed pressure running of a 330 MW unit circulating fluidized bed(CFB)boiler

the desulphurization efficiency decreased and the slagging problem seemed getting serioud.Against this

performance tests were carried out

under various working conditions.The effects of control parameters

such as the bed pressure

the particle size of limestone

the operational level

and the output of limestone conveying system in the running process

on desulfurization efficiency of the CFB boiler were investigated.The results show that

insufficient output of the limestone conveying system and undersize of limestone particles were major reasons for the low desulphurization efficiency of this unit.On this basis

several countermeasures were put forward

like increasing the output power of the limestone conveying system

enlarging the particle size of limestone

increasing the operational oxygen content and the primary air volume

raising the secondary air volume at higher locations

and others.