The air cap of a 130 t/h circulating fluidized bed(CFB) boiler for unit no.4 in Shijiazhuang Chengfeng Thermal Power Co Ltd had been seriously worn-out.The causes resulting in worn-out of the air cap for said boiler have been analysed

and corresponding technical retrofit being carried out.Results of test show that the resistance of empty plate after retrofitting the air cap has been reduced

the air distribution being uniform

and the fluidizing state being good;annually saved electricity being valued at about 0.119 million yuan

saved coal being worth 0.089 million yuan

and saved expenses for replacing spare parts of the air cap hitting about 0.049 million yuan

having remarkable economic results.