www.saVRee.com Deaerators Explained pg.
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Deaerator System
Boilers generate steam which is delivered to the process. Some of the steam transfers its
energy to the process and condenses; the resultant water is termed condensate.
Condensate is gathered throughout the steam system and is returned to a central storage
tank, this is either an atmospheric feedwater tank, or a pressurised feedwater tank
(deaerator).
Spray Deaerator
Makeup water replaces water losses within the system. Water losses may be an
unavoidable part of the process e.g. steam cleaning of glass bottles in the edible food
industry, or, may be due to leaks or evaporation losses etc.
When condensate reaches the feedwater tank, it is termed feedwater, as it is then fed to
the boiler. Similarly, when makeup water enters the feedwater tank, it is thereafter termed
feedwater.
Systems with low condensate returns must continually add large amounts of makeup
water. Continuously adding makeup water introduces more untreated water to the system
compared to when reusing condensate that has already been treated. For these reasons, a
deaerator is much more likely to be installed on a system with low condensate returns than
one with high condensate returns. It should be noted that systems with low condensate
returns will have larger operating costs due to higher water consumption, higher
heat/energy consumption (water has to be heated before entering the boiler) and higher
chemical treatment consumption.
The solubility of dissolved gases in water reduces as the temperature of the water
increases. In order to raise the boiler feedwater temperature, low pressure steam is
supplied. The steam transfers its heat to the feedwater until the feedwater approaches its