The current drum level measurement in power plants can't indicate the real level


#1

Base on our investigation,the current level measurement system can’t indicate the real level as the working environment inside and outside the drum is totally different which will cause big deviation.

And the water inside the drum is unsaturated as the feed water input. When the drum pressure is 1400psi, the deviation is up to 2 inches.

And when the drum pressure is beyond 2000psi, the deviation is up to 4 inches. Much higher drum pressure, bigger deviation and less safety. There is one direct way to check the problem which is opening the drum to check the water mark during outage period.

The high water level and low water level operation will cause big accident and MFT for power plants which are the hidden danger and can lead to big loss for the power plant.
We do hope more and more power plants can realize that and cares their boilers.

Any questions or disagreement, welcome to discuss.


#2

@Jessielau-0219

Check these articles, may helpful.

https://www.crossco.com/blog/density-compensation-steam-drum-level-measurement

https://control.com/thread/1506592640


#3

Well, Santhosh, thanks for sharing. Yes. For the differential pressure level gauges, It is used the formula to do the density compensation which is the link you shared with me regarding to the wet leg level measurement.

Well, in the formula, the water density in the drum and the water density in the reference leg( the reference leg temperature are not even in different sections of it) are hard to known. After investigation, we found the two items will cause big deviation when the boiler is in the high pressure and high temperature operation.

That’s the reason we say the current drum level measurement system can’t indicate the real level. And for the U tube level gauges( such as conductivity probes and mica bi-color gauge glass), the water temperature inside and outside the drum are different.

The water temperature inside the reference leg is lower than the water temperature inside the drum which will lead to the deviation. R-levels delete the items lead to the deviation in the differential pressure gauges as well as in the U-tube level gauges. Anyone who is interested in the technologies, welcome to contact me at [email protected]


#4

@santhosh Well, Which I stated is that the current traditional level measurement instruments can’t indicate the real level inside the drum as well as the instrument which you shared with me. I would like to share with you one articles which will be helpful for understanding. http://www.rlevels.com/d/file/services/2019-03-27/Big%20error%20from%20the%20Traditional%20Instruments.pdf

And any questions, welcome to discuss and communicate.