The types and features of waterwall in oncethrough boilers have been briefly described.Through analysis of metalic wall temperature deviation under various conditions of the waterwall in the first home made supercritical oncethrough boiler of Huaneng Qinbei Power Generation Company

the results obtained are as follows: the outlet temperature deviation of vertical waterwall is obviously greater than that of spiral waterwall;adopting spiral waterwall in the lower part

and adopting vertical waterwall in the upper part

the problems of heat transfer deterioration and nonuniform distribution of the flowrate in vertical waterwall under offdesign condition can be comparatively well solved.The operation under offdesign condition is good

the economic behavior and reliability of boiler startup all to be reached a level of a largecapacity oncethrough boiler.