Abstract: By adopting several measures, which include that to increase the auxiliary steam as the deaerator heating steam source to keep the water temperature of the deaerator, to run one electrically driven feed pump and to raise the feed water temperature, the turning wet state to dry state of the boiler under conditions of low steam pressure and low load was implemented. This is improvement of the wettodry state turning; many problems existing in the wettodry state turning process were solved; the operation time in wet state was shortened; and the fault rate in wet state and the wettodry state turning process was reduced. Combining with the characteristics of the domestic 600MW supercritical oncethrough boiler, in the start up process of the supercritical oncethrough boiler, the optimized control of the wettodry state turning was carried out, and the purposes of the safety, the energy saving and the environment protection were realized.

Key words: supercritical, once-through boiler, optimized control, safety, benefit, environment protection