Deaerator Pressure Curve vs Boiler Load
Deaerator Pressure Curve vs Boiler Load
(OP)
Hi,
there is two different Curves for "Deaerator Pressure Curve vs Boiler Load" in my documents as per attached picture. please describe which one is correct?
http://fil es.enginee ring.com/g etfile.asp x?folder=6 eecc576-1f 72-43fc-ae 67-2bc7d88 ac042& file=untit led001.JPG
there is two different Curves for "Deaerator Pressure Curve vs Boiler Load" in my documents as per attached picture. please describe which one is correct?
http://fil





RE: Deaerator Pressure Curve vs Boiler Load
If the curves relate to feed water heating and that has something to do with circulation flows within the boiler as a function of load, then ignore the above and change my answer to the opposite draft.
Still all in all, I do not have experience with deaerators that vary their operating pressure with boiler load.
rmw
RE: Deaerator Pressure Curve vs Boiler Load
RE: Deaerator Pressure Curve vs Boiler Load
Not all of them.
Some are designed to operate at low pressures (about 5 psig)
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-MJC
RE: Deaerator Pressure Curve vs Boiler Load
These curves have been mentioned in "Deaerator Sizing Criteria" documents in two different CCPP projects, now i want to know that in lower HRSG load (25%,50%,75%) the deaerator pressure is lower or higher than the normal operation (HRSG load=100%)?
I think that the curve on the right should be correct but I need a good reason to be sure!
RE: Deaerator Pressure Curve vs Boiler Load
RE: Deaerator Pressure Curve vs Boiler Load
In a CCPP, a changing pressure profile is also seen with integral deaerators except that as the gas turbine load is reduced, more heat load shifts to the back of the HRSG and the pressure in the low pressure section and/or DA goes up due to higher steam flow rates. So if your application is a CCPP, I'd say that the curve on the right is actually closer to what I'd expect although I'd think it would be a little smoother drop with increasing load. Then again, I don't know what types of pressure controls are being utilized for either the deaerator or the steam turbine throttle flow. Either of these could have an effect on the curve's shape. For example, if the turbine and/or duct burner are using a high sulfur fuel, the integral DA may require pegging steam from a higher pressure source (IP or HP drum) to keep it's temperature comfortably above the acid gas dew point in the exhaust to avoid gas side corrosion. This could cause a flat operating pressure curve as shown in the right side curve. This curve seems to flatten at about 4 kg/cm2-A or about 60 psia. This would give a saturation temp of about 290F which might be high enough to deal with relatively small amounts of sulfur.
RE: Deaerator Pressure Curve vs Boiler Load
So.... a CCPP deaerator is a certain "special animal" and operates unlike the ancient deaerators that all of us are familiar with !!??
RE: Deaerator Pressure Curve vs Boiler Load
The question in this thread dealt with typical pressure profiles for deaerators vs. boiler load. My post notes that an Integral Deaerator in a CCPP may likely be inversely related to regenerative Rankine power plant unless the Integral DA is pegged to reduce gas side condensation. If the DA is of the "ancient" variety and its steam supply is pressure controlled directly by the operator, then its pressure profile doesn't change with boier load.
RE: Deaerator Pressure Curve vs Boiler Load
The only CC deaerators I ever messed were were vacuum deaerators which were an integral part of the condenser and operated at a negative pressure.
Thanks hrsgguru for your explanations.
rmw