Through analysis and study of practical operation situation for anthracite firing boilers with w-shaped flame and twin-arch combustion of more than twenty 300 MW units having been put into operation in our country

it is considered that the main causes of lower burn-up ratio are as follows: bad match of coal pulverizing system

furnace and burners; deviation of air/fuel ratio among individual coal-powder pipelines is too large; the mixing behaiour during the final stage of combustion is not good. Hence

it is suggested that the four corner tangential firing or in-opposition arranged swirl firing mode is still an optimal mode for anthracite firing boilers.