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Steam cycle feedwater preheater level compensation
3

Steam cycle feedwater preheater level compensation

Steam cycle feedwater preheater level compensation

(OP)
Hi,

Do level transmitters in FW preheaters need to be compensated for pressure?

RE: Steam cycle feedwater preheater level compensation

you have to be a little more specific, preheaters come in all sizes and shapes, layouts and designs.

generally level transmitter/controllers do not require compensation if installed properly...

RE: Steam cycle feedwater preheater level compensation

They need to be compensated for temperature not pressure.  It is a common issue in HP FWH's.

The water in the transmitter IF it is located away from the body of the FWH to any extent and outside of the insulation especially will be colder than the water in the heater and hence more dense.

Therefore it will take more head of less dense water inside the heater to balance the level of the colder more dense water in the transmitter or gage glass, so you need to do a calculation and estimate the error in the transmitter based on the geometry of the transmitter attachment to the heater.

The same is commonly done for boiler drum level indication as well.  You may already have such a system for the boiler (if it has a drum, of course that is - not supercritical.)

rmw

RE: Steam cycle feedwater preheater level compensation

(OP)
They ate shell and tube preheaters. I always understood as you say that it would need to be compensated for temperature and not pressure. Apparently the pressure is used to compensate for the turbulence that occurs when steam condenses from the steam extraction.

RE: Steam cycle feedwater preheater level compensation

(OP)
thanks for the article, our levels are local indicators are from Ktek as well and the signal is transmitted by a Vegaplus radar.

RE: Steam cycle feedwater preheater level compensation

Well, you got me there... "the turbulence that occurs when steam condenses from the turbine extraction".

I have no idea what that means.

There is a gradient from the end opposite the drain end (or there wouldn't be flow toward the drain) and there has to be some action caused by the droplets falling from tubing, but turbulence????

What would cause turbulence?  And further more, if there is any, how would pressure compensate that?

rmw

RE: Steam cycle feedwater preheater level compensation

Usually for feedwater flow measurements, temperature compensation is employed. For steam flow measurement, both temperature and pressure compensation are used.

RE: Steam cycle feedwater preheater level compensation

Oh, I thought we were talking about level.

rmw

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