The problem of somewhat lower main steam temperature for 2045 t/h boiler in one power plant has been analysed. It is believed that the cause is mainly due to unreasonable distribution of steamrelieving heating surface area in the furnace and heating surface area of the superheater. For this reason

many methods

such as reducing the area of economizer

increasing heating surface of the lowtemperature superheater

raising the height of burners

and carrying out thermal isolation of outlet pipes of the waterwall etc.

have been adopted

making the main steam temperature and the reheated steam temperature all being enhanced to the rated value of 540 ℃

the exhaust gas temperature being also controlled to a designed value of 140 ℃

the combustibles in fly ash having not in creased

the boiler efficiency having reached to 94.14%.