Steam turbine condenser vacuum problem

The boiling temperature and pressure of water are intimately linked.

It sounds as though some sort of inward leak is causing the loss of condenser vacuum, and the higher temperature is a symptom of the lower vacuum and indicating the leak.

Check your crossover valve used for back washing. It may be leaking by or have something stuck in it.

Check for condenser leaks which develop with increasing temperature.

What method are you using for oxygen control: hydrozine injection?

Basically the only way to remove dissolve oxygen is by using deaerator. According to EPRI guide for feedwater treatment, hydrozine disallowed in order to prevent FAC. We have on-line DO2 which located at condenser extraction pump outlet, deaerator inlet, deaerator outlet, HP BFP and LP BFP. Based on my observation the DO2 is normal.

I do not know either high outfall temperature is related to the condenser vacuum problem.

Global warming......cross over critical point.

Directly related.

MR. GUY

I recall similar experience we faced on Sulzer turbine during mid nineties.

Fluctuating condenser pressure/vacuum.

Air was getting into through gland. Actual culprit was a simple 'steam trap' at glad steam circuit. The malfunction of this trap was allowing condensate intermittently into gland. This irregular supply of steam to gland led air on and often to turbine and intern to condenser.

Dear Yesyen, it happened when load reduced to minimum i.e 70 MW of steam turbine gross output. Gland steam pressure approx. 0.22 bar. FYI, the gland steam pressure throttled manually by throttling the bypass manual isolating valve. CV unable to put in service.

Dear friend,

You are mentioning about the condeser problem. As per the information provided by you there is a rise in outlet temperaure for increase in inlet temperature.

Please check the following items.

1. Check the condeser cooling water flow.

2. Check your cooling water inlet take off point. Is it nearer to any industrial waste out let point.

3. Provide fin type arrangement with cooling fan provision at the condenser inlet pipe line to reduce inlet temperature such that you can limit your outlet temp as well you can increase the load.

4. Check vacuum tightness effectively.

5. Check your boiler feed water chemistry for effective evacuation of dissolved oxygen in feed water.

With regards,

SAM

Thank you Guest,

We have on-line DO2 reading and our chemist/ lab department also will do the grab sampling in order to get the DO2. The problem is the accuracy of reading itself. Sometimes reading recorded by grab sampling is more higher than the on-line reading. So, quite difficult for us to accept it due to one of the factor of air ingress is high DO2 reading. Limit is <10ppb.

Our combined cycle plant just coming back from major overhaul but the problem on condenser vacuum still persist. Currently, one steam air ejector in service but the motive steam pressure is 16.5 bar where slightly above the setting pressure, 14.0bar.

Before we managed to put one main ejector in service, both steam ejectors were in service on auto with motive steam pressure at 14.0 bar. Observed condenser outlet pressure improved to 1.2/0.9 bar (press gg is located before the outlet motorized valve). The TTD is 7.6 deg C for both condenser w/boxes. LP turbine exhaust temperature roughly at 43 deg C compared to 47 deg C before major overhaul.

Our plant just installed with PI system. Based on the trend, it showed the high outfall temperature and low condenser vacuum happened just before the sea water tide level increased to maximum. Then the outfall and condenser vacuum will be back to normal operating reading when the tide level at maximum.I do not know if the hot water from the outfall flowing back to the intake lagoon of cooling water pump which caused the condenser inlet temperature increased. As far I'm concerned, sea water extracting by cooling water pump into condenser quite deep in the water.

boleh jadi bro ada back flow from outfall to CW intake if ur condenser inlet temp also high. Global warming pun ye juga tapi lu boleh check CW intake screen da penuh kupang kot. CW flow tak cantik pun boleh kacau vacuum during tide changing. SJAE steam supply lu x payah increase press kalau nozzle n defuser masih baik, too high press boleh senak lu punya SJAE.. performance drop bro. Air ingress lu boleh tau dgn result DO2. Paling mudah nk buat leak check pakai freon gas, pasang detector kat SJAE exhaust pastu lu sembur la gas tu kat yg mncurigakan. Condenser cleanliness factor kn jaga bro, ball cleaning system kena jalan bro.

You can check the following items for your problem

1.Check your sea water intake temperature

2.check your sea water supply line to your ST whether it is provided with filteration equipment.This may be choked.

3.Any air ingression through any valves which connected in the vaccumm system.Check your sealing water pressure.

4.If you suspect any leak from the steam side then your condensate temp will raise.

5.check the primming of your sea water line.Some air lock also will reduce the cooling and it will detoriate the vaccumm.

your vacuum readings should be in bar(g) or Bar(a)?

There might be a leakage on your bypass on your HP/LP valve.