Tray-type deaerator

A schematic diagram of a typical tray-type deaerator

    The typical horizontal tray-type deaerator has a vertical domed deaeration section mounted above a horizontal boiler feedwater storage vessel. Boiler feedwater enters the vertical dearation section above the perforated trays and flows downward through the perforations. Low-pressure dearation steam enters below the perforated trays and flows upward through the perforations.  Some designs use various type of packing material , rather than perforated trays , to provide good contact and mixing between the steam and the boiler feed water.
     The steam strips the dissolved gas from the boiler feedwater and exits via the vent at the top of the domed section. Some designs may include a vent condenser to trap and recover any water entrained in the vented gas. The vent line usually includes a valve and just enough steam is allowed to escape with the vented gases to provide a small and visible telltale plume of steam.
     The deaerated water flows down into the horizontal storage vessel from where it is pumped to the steam generating boiler system. Low-pressure heating steam , which enters the horizontal vessel through a sparger pipe in the bottom of the vessel , is provided to keep the stored boiler feedwater warm. External insulation of the vessel is typically provided to minimize heat loss.