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Boiler drum level measurement problem with DP transmitter

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EthyleneInstrument

Electrical
Mar 27, 2011
16
Hi sir
For level measurement of boiler drum I want to instal DP transmitter at a low elevation of drum, and filled low side of transmitter with water by using condansate pod.
I calculated LRL and URL of transmitter.
When I looked at rosemount calculation document (attached file), there are small difference, because of steam height pressure.

Does height of saturated steam act transmitter?
Saturated steam look like gas, its pressure must press everywhere of drum, look like gases.
Isn't it?

For a normal Drums (not boiler drum) , there are 2 phase, gas and liquid.
when we connected Differential pressure transmitter,
Low side of transmitter pressure measure= Drum pressure
High sideof transmitter pressure measure= Liquid height pressure and Drum pressure
Transmiiter substract these pressure and find olny Liquid height pressure .

For boiler drums (on attached file):
Low side of transmitter pressure = drum pressure (OK)
High sideof transmiiter pressure = Liquid height pressure and saturated steam height pressure and drum pressure
Transmiiter substract these pressure and find Liquid height pressure with saturated steamheight pressure.

Is it normal, Does height of saturated steam act transmitter?
Saturated steam look like gas, its pressure must press every where of drum look like gases.Isn't it?

It is not liquid, does it have height pressure??

Can u look at attached calculation?

Thank you


 
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the steam density is rarely taken into account in low pressure boilers, but as your calc sheet suggest it can have an effect
that cannot be ignored....

you can calculate the error
 
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