Deaerator Pressure
Deaerator Pressure
(OP)
Hello, I am a professional engineer in Ireland. I have little knowledge about deaerators. As far as I know, deaerators have a fixed pressure which can be taken as 1.2 bars. Does it mean that all streams coming to and going from deaerator should have the same pressure, for ex. for a cogeneration plant. Thank you. DD





RE: Deaerator Pressure
http://www.spiraxsarco.com/learn/html/3_21_01.htm
RE: Deaerator Pressure
The function of a DA is to remove gases that might cause corrosion from the feedwater. The effectiveness of a DA is determined by how close the actual temperature of the water is to the saturation temperature. This is because the solubility of gases in water reduces as the actual temperature approaches the saturation temperature.
If the actual temperature equals the saturation temperature then there is no gas in the water. Think its called Henry's rule.
As a consequence, in coventional plant the pressure is selected on the basis of a cycle optimisation. I have worked on plant with DA pressures above 7 bar abs. With the advent of combined cycle plant operating at different pressures the DA pressure is dependent on the lowest boiler pressure.
The reason for keeping the DA pressure above atmospheric pressure is to prevent inwar air leaks into the DA.
Regards,
athomas236
RE: Deaerator Pressure
RE: Deaerator Pressure
RE: Deaerator Pressure
rmw
RE: Deaerator Pressure
What has not been mentioned in the threads above is the affect that DA pressure has on boiler feed pump NPSH. This operating pressure also indirectly affects required DA elevation in the plant layout
The DA, storage tank and the feed pump are part of a single system....
MJC
RE: Deaerator Pressure
Only if the DA was not doing it's job, and the water in the storage tank was sub-cooled with respect to the operating pressure of the DA would there be any effect, and this adverse condition would actually have a beneficial effect on the NPSH.
rmw
RE: Deaerator Pressure
RE: Deaerator Pressure
Yoy lost me with that statement. What did you mean by saying that oxygen and CO2 are uncompressible gases?
Milton Beychok
(Contact me at www.air-dispersion.com)
RE: Deaerator Pressure
RE: Deaerator Pressure
I am trying to figure out if he means 5 psia or 5 psig. I think he means 5 psig & saturated conditions (which would give his 230 oF).
RE: Deaerator Pressure
I have been working with DA'S for about 3 months and am in no way an expert on the subject, thanks for the help.
RE: Deaerator Pressure
I work in a nuke plant. Most nukes don't have dearator tanks. As I understand one deciding factor during the design of our plant was that the addition of a D.A. meant that each of our 3 feedpumps would be capable of providing 50% flow so we have a built-in spare. Without the d.a. we would need all 3 feedpumps to reach 100% flow.
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RE: Deaerator Pressure
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