This short informational article focuses on the tray type variation for now. Apart from the tray type deaerator, the other alternative is that of the spray type, in case interested readers would like to hurry along with extending their reservoir of knowledge. For the time being, do note that the tray type deaerator is also commonly known as the cascade type deaerator. One variation (there are others) is vertically and dome shaped.
It is usually mounted on the top of a horizontally-aligned cylinder. This cylinder in essence becomes the ‘deaerated boiler feed-water storage tank’. Boiler feed-water is allowed to enter a vertical deaeration section above perforated trays. This water then flows down through the perforations. Low-pressure deaeration steam then enters below the trays. Then it flows upwards through the perforations.
Some deaerating designs will, however, be using different types of packed beds, as opposed to the commonly used tray type (or spray type) deaerator. The motivation is to provide good contact and mixing between steam and boiler feed water.
Back to the tray type deaerator then. Steam strips dissolved gas from the boiler feed-water. It is collated to a vent valve at the top of the cylinder. Deaerated water flows into its horizontal storage vessel. Here, the water is then pumped into the steam generating boiler system. Low pressure heating steam enters the cylinder through a sparger pipe. This pipe is located at the bottom of the cylinder.
The object of the exercise is to keep all feeder water warm.
Note that whilst both tray type and spray deaerators are classically defined as standard, no one tray will look the same. The designers and developers of the technologies regularly respond to certain unique features or specifications as clarified to them by given companies.