Abstract: The dissolved oxygen in the condensing water of 1000MW unit at lowload operation exceeded the standard value. Combining with the practical status of the unit, the whole checkup process of overproof dissolved oxygen in condensate was described in detail. The reasons caused the standard value exceeded were analyzed, the proper measures were worked out, and the problem of overproof dissolved oxygen in condensate was solved thoroughly. This provides reference for solving the similar problems of the similar units.

Key words: ultra-supercritical unit, dissolved oxygen in condensate, the reason caused standard value exceeded, solving measure