Poor coal quality causes combustion instability

thus large amount of fuel oil were necessary for a 360 MW unit with W-flame boiler.Therefore

against the low temperature level in the furnace of the boiler

retrofitting of the refractory belt was conducted.After the modification

combustion condition is significantly improved

and the flame stability is also enhanced.Moreover

fuel oil consumption decreases

and no oil is needed when the unit load is about 200 MW.Besides

the exhaust gas temperature reduces from 170～180 ℃ to 150～160 ℃

and the bottom ash and carbon content of fly ash decreases too.