High Turbine Exhaust Pressure

I couldn't give the OP a GA for supplying the answer, so here you go.

Aw, shucks.

"The condensate is at partial vacuum. The cooling water is at a pressure above atmospheric."

Well said, cooling water getting into steam side of condenser would decrease the efficiency of condenser, thereby the exhaust pressure would naturally rise. Yes, as suggested, fix the leak by plugging the tube or preferably re-tubing the Leakey tubes.

Actually fluid leaking in wouldn't decrease the condenser efficiency, it would increase the efficiency because it would bring the temperature closer to cooling water inlet temp (lower) which would improve vacuum, not degrade it.

Boiler level increases and carry over and turbine damage would be the heartbreak there....or possibly severe (catostrophic?) corrossion problems if chemestry were left unchecked and coolingwater was less than pristine.

The problem the conditions are pointing to is one of air being drawn into the condenser. That is the reason vacuum is diminishing.

Flee to me remote elf.

....which is absolutely fine, except for two things:

• The OP hasn't mentioned air leaking in
• This particular hypothesis disregards the OP's claimed deterioration in condensate quality

Pwslack...

The OP hasn't mentioned air leaking in, but then again the OP is asking what might be causing the problem, so if they are uncertain of the answer, we shouldn't judge too harshly if they don't specify the exact answer when posting the question.

Degradation in quality of condensate does not, in any way, disprove that air leaking in is the likely cause of loss of vacuum...

There may be both chill water and air being drawn into the condenser, but the air would still be the cause of vacuum degradation.

Alternately just air might be leaking in to the condenser. Depending on the specific steam plant chemistry, and the plant condition, degradation in condensate quality could be seen fairly quickly as a result of air introduced.

The real kicker here is that water alone leaking into the condenser would actually have a tendency to improve vacuum initially. The reduced temperature, from direct mixing, would mean lower pressure. The condensate pumps will not discriminate against the water that has leaked into the condenser. It will be pumped out with the condensate. it certainly won't get stuck somehow filling up the condenser.

Fluid leaking in is far more likely to be noticed first in boiler chemistry, or perhaps high boiler level, or carry over. It certainly is not indicated nor would it directly cause slow loss of vaccuum.

If you still disagree, please explain what you believe is happening to the contrary.

I don't know how clean your cooling water supply is, but it would have to be amazingly clean for loss of vacuum to be the primary indication of cooling water leaking into the condenser.

Chemistry should be screaming at you before changes in vacuum if you are drawing cooling water.

you are losing vacuum because air is leaking into the condenser. The air of course doesn't condense and is overwhelming the eductor.

Sure you might also hahe cooling water leaking in, but that will be noticed other places, and is not the reason you are losing vacuum.

Btw... shame on everyone who rated the guest as 'off topic' and jumped on the 'ga' bandwagon for the seemingly obvious but offbase quick response (from someone who otherwise, very often gives very good responses.... )

Flee to me remote elf

thanks flee... ultimately leakage found in condenser..

... you are welcome.

Just to clarify for everyone, you are stating that ultimatey, AIR was leaking into the condenser, right?

The heat exchangers are double wall tube in shell design with tell tales, right? This would make it very difficult for cooling water only and not air to be drawn into a leaking condenser..

.but i'll wait for your confirmation.

:-)

Actually the leakage found in the line which entering into the condenser.. and this line is not the line through which normal condensate flow.. the purpose of that line to drain out each stages of turbine during shutdown. so air ingress was continue through that portion.

:-)