Compensation for level measurement

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Thread Starter

bhargav purohit

in boiler drum level measurement, we do density compensation as density changes with pressure. So in calculation we considers change in density with drum pressure.

But density also changes with temperature. Then why we don't consider this? if yes then how?
 
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Bruce Durdle

Boiler water is saturated so the temperature and pressure are related - if the pressure is known, the temperature and density are as well.
 
The boiler drum is at saturation conditions when operating. On the saturation line, if you know the pressure, the temperature (and density) is fixed. Look at a Molier chart.

Also, it is easier to get a pressure measurement of the drum than a water temperature measurement. (Pre-saturation, during startup, would be the only time the temperature measurement would produce a more accurate density calculation.)
 
most use correlation or table look ups,

Some of the early vendor suggestions used temperature based correlations under the assumption that the boiler basically operates in a saturated state.

Grab you steam data and generate the correlation you need.
 
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