Built-in deaerization plant

The utility model belongs to a deaerization plant which is used in thermal power generation industry, nuclear power industry or petrochemical industry and other industries. The built-in deaerization plant comprises a deoxidizing water tank, a disc single nozzle, a main steam heating device, an assistant steam heating device and a water outlet pipe joint. The utility model is characterized in that a water retaining cover is arranged in the deoxidizing water tank, the part of the disc single nozzle, which is in the deoxidizing water tank, is arranged in the water retaining cover, a big water retaining board and a small water retaining board are arranged in the deoxidizing water tank, the big water retaining board is arranged between the middle part in the deoxidizing water tank and the disc single nozzle and is close to one side of the disc single nozzle, the upper end of the big water retaining board is arranged above a normal water level line in the deoxidizing water tank, a channel is left between the lower end of the big water retaining board and the bottom part in the deoxidizing water tank, the small water retaining board is arranged between the bottom of the middle part in the deoxidizing water tank and the water outlet pipe joint, and the upper end of the small water retaining board is arranged under the normal water level line in the deoxidizing water tank. The utility model has the advantages of small effluent oxygen content and steam exhaust loss, stable running, low running maintenance charge, compact structure and long service life.