The pipe wall overtemperature

and even tube burst

has repeatedly occurred on high-temperature convective heating surface of boilers for 2×700 MW units in Zhuhai Power Plant.Analysis from three aspects namely the coal sorts

the temperature distribution of flue gas in the flue duct

and the flow rate distritution on the steam side

shows that the tube burst due to overtemperature was mainly resulted from deviation in flow rate distribution on the steam side

the deviation in temperature distribution on the flue gas side being less important.After adoption of the following measures

i.e.improving flow rate distribution on the steam side to decrease the deviation

enhancing high-temperature resistant performance of the materials

and increasing the monitoring points to strengthen the supervision in operation

etc.

the overtemperature problem occurred on the third-stage superheater and the third-stage reheater for boiler no.1 has been basically solved.