high backpressure

[sasuan]

I work at a 800 MW coal fired plant. About a week ago, the condenser backpressure on the unt went up. We checked all familiar spots.
The waterbox is clean- no pluggage.
No air in leaks- vacuum pump flow is good.
Water level of inlet waterbox is full
But the only thing is the hotwell temp is about 15 deg higher. No tubeleaks suspected.
So, we checked all the drain valves to be closed.
Can anybody think of anything else.
The system is a condensing turbine with a surface condenser.

 

[SamOntario]

Check cooling water flow and temperature and carry out a condenser performance test.

 

[SamOntario]

Though you said you have checked all air leaks, from my experience, its likely a vacuum leak at most unlikely locations. Check also LP feed heater flash box drain.

 

[sasuan]

The dissolved O2 is very low, thats the reason i', thinking tnere cannot be any air leaks..

 

[SamOntario]

"dissolved O2" is not a good indicator of air leaks. If cooling water is running normal, the only thing that could cause high back pressure is air leak.

Good luck to your search for identifying your condenser problem.