Backpressure calculation

[ksprague]

I work in a 160 MW coal fired Power Plant. The turbine is a condensing turbine with a surface condenser. After our last outage it was noticed that one of our three backpressure indications started reading 2 inHg different than the others. The one that is reading different is taken 30 feet higher than the others. Our Technicians believe that the difference in elevation (30 ft) is enough to give us the 2 inHg difference. Seems like a lot to me. Any comments?

 

[abeltio]

yes, it is a lot.
what where they reading before the outage?
does your design spec call for a bias due to the difference in location (correction for density, temperature?)
HTH
Saludos
a.

 

[Flyash]

2" Hg is big. The 30 foot height will not affect the pressure reading a measurable amount. Your are talking about a column of steam under a vacuum. You would need in the order of 20,000 ft to get that pressure difference.

Just a thought what do your turbine exhaust temperatures read. It is a saturated system and they should match up.

We've had problems with water in the sensing line throwing the backpressure indication off. I don't like to see the pressure indication off more than .25".

Maybe you have a vacuum leak at the sensing line connection.