Armored thermocouples was installed on heating surface tube wall of 4×1 000MW unit boilers in Huaneng Yuhuan Power Plant to obtain the tube wall temperature data of the boiler heat surface during unit start and shut down process.On the basis of correlation analysis method

the relationship between the inside and outside furnace wall temperature

the inside furnace wall temperature and unit load

the outside furnace wall temperature and unit load

and other parameters were investigated.The results showed that

during the unit cold state start-up

the inside furnace wall temperature was related to the unit load dramatically;the outside furnace wall temperature showed a strong dependency on the unit load for the last three heating surfaces but not the second stage superheater;the inside and outside furnace wall temperature also had significant correlation.While during the unit operation

the correlation between the inside furnace wall temperature and the unit load decreased gradually along the gas flow direction;the outside furnace wall temperature and unit load exhibited no obvious correlation;the inside and outside furnace wall temperature showed strong correlation on the second stage reheater but no significant correlation on each superheater.