The feed water of unit no.1 and unit no.2 in Guohua Panshan Power Generation Co Ltd has adopted oxygen treatment

the accumulated operation time has reached ten years

the failures of tube-blockage and tube-burst have never occurred due to oxide skin peel-off.It has discovered during inspection of xoxide film and oxdie skin formed on superheater and reheater of boilers for said units that there is greater difference between them.For this

the causes leading to formation of oxide skin have been studied

results show that:(1)the oxide skin was the oxidation result of metal in high-temperature water and steam

and it wasn't originated from dissolution of molecular oxygen in the water and steam

that is to say the oxygen treatment of feed water had little influence upon formation of oxide skin;(2)certain oxide skin on reheater tube had peeled off

this was mainly related to factors

such as combustion conditions in the boiler

temperature rising and dropping speed during start-up and shutdown of the units

as well as quality of materials used etc.

and measures for preventing formation of oxide skin have been given.