3.2 De-aerator heater
A cross-section through a typical de-aerator heater is shown in Fig 3.28. Feedwater is sprayed or cascaded over a series of trays where it is heated and de-aerated by the bled steam from the turbine. The process is described in detail in Section 7 of this chapter.
The non-condensable gases and a certain amount of steam are drawn off from the vent. The vent condenser recovers the heat in the steam and non-condensable gases drawn-off from the de-aerator head. The gases are then discharged to the condenser to be extracted finally by the air extraction equipment.
Other designs of de-aerator heaters, which use other means of exposing the condensate to the heating and scrubbing action of steam, are described in detail in Section 7 of this chapter, but the principle involved is the same in all cases. The heated condensate and the condensed steam drain from the head into the de-aerator storage tank.