Reg Steam Turbine Exhaust Hood Temperature

Any competent engineer would already know this.

You should already have the operating manual, know how to use it and already know the answer to your question.

Any competent engineer would at least have contacted the manufacturer of the equipment and told them that he was completely ignorant of how to run the equipment at capacity and that his dog had eaten the operator's manual and you never had a good operator, so you are lost.

Seriously, contact the BHEL engineering department, or field engineering department of the manufacturer and be willing to PAY THEM to teach you how to operate their equipment!

Bharat Heavy Electricals Ltd.

Why haven't you cleaned up the raw water, then?

that heat could distill a lot of clean water.....

Why is the raw water quality so bad ? What is the source of the water - ocean, lake or river ?

Was this a power plant that was simply thrown onto a site without consideration of raw and processed water ? was the plant recently purchased from some other corporation and you are now stuck with the operation ? ( Sounds like a typical MBA trick to me)

Any raw water supply to a steam condenser must at least be strained. This should take care of most solids. If there is marine/biofouling you may have to periodically shut down and shock the system with chlorine or bromine.

Are you sure your GT and ST are designed to operate together? It seems that your GT has an extraordinary quantity of waste heat available even if it is running 35 MW whilst the ST is producing 19MW on steam from the HRSG. That vacuum you mention is that -0.61 Bar? That is not a good vacuum if so, and any ST with an exhaust temp of 75C is not being cooled well at all, or the entire system is a bad, bad design.

If condenser tubes are fouled with slime, use chlorine or chlorine combined with bromine to remove this on a continuing basis. If tubes are blocked with debris, then use pit screens to remove debris from intake or cooling tower before it enters the pumps, transfer lines, and condenser.

It appears you are having tube failures, as you stated, and thus there are problems with water chemistry that will cause (1) corrosion in the HRSG, transfer of corrosion product to ST, damage to blades and membranes that result in lowered output and efficiency, and (2) deposits of corrosion products on condensate side of condenser tubes, which leads to degradation (corrosion) of the tubes, transfer of copper into downstream equipment including the HRSG, etc. and will result in major equipment failure at some point. You must get the water chemistry under control, and you must clean up the cooling water to point that (1) no debris is present, and (2) water hardness, alkalinity, and silica are within manufacturer's best recommended practice guidelines. Otherwise, be prepared for multi-million dollar mistakes, that can be cured for a few thousands.

Dear Friend,

It appears from your posting that the VACCUUM is the route cause for yor problem, hence you have to deeply concentrate on the Condenser and its Water Circulation, Free Flow of Exhaust Steam in to the Condenser.

Simultaneously check up for the following.

1. Design aspect of the Condenser in terms Heat Transfer Co.Eff.

2. What is Log Mean Temp.

3. What is Flow Rate of Water, What is the In-Let Temp.

4. Whether the CONDENSER COOLING SURFACE is sufficient.

5. Whether the Condensate Removal from Condenser is Perfect.

6. Whether the condensate is submerging a portion of the Tubes in the Condenser etc.

DHAYANANDHAN.S

A condenseing steam turbine runs best with a vacuum of 28 to 29 inches of vacuum. The vacuum alarm is normally set at 24 to 25 inches of vacuum and the vacuum trip is set at 21 inches of vacuum. This is to protect the steam turbine. If you cannot run within these parameters then yoou need to shut down and fix your vacuum leaks. You can locate them while the unit is running using freon or FX gas and a detector. A unit running at 27 to 29 inches of vacuum will have an exhaust hood temperature running from 90 degrees F. to 120 degrees F. Anything above this starts to degrade the efficiency and load of the unit. Hope this helps you.

From the appearance at the surface of what OP has stated, I am not entirely sure he has vacuum leaks. I think he has tubes that are shot, since he mentioned tube leaks (at least as I saw it). I agree with everything you stated, just not sure that air ingress is the problem. I think he has bad coolant quality in terms of trash, blocking the tube sheet, may have heavy bacterial sliming of the tubes, and heavy corrosion of tube materials due to poor process control on both condensate and coolant sides of the issue.

OP needs to go back to square one by speaking with engineers at the OEM of the condenser, get the best recommended practices states by the OEM, clean up his act regarding water treatment, perhaps re-tube the condenser, and start over. At a minimum, he needs trash screens, chlorine and/or bromine, a general brushing/rodding of the condenser tubes, leak tests, vacuum seal tests, steam turbine gland seal tests (along with the usual outage repair of these items), and needs to be recording data at least on a daily basis, if not having instruments installed in situ (in the condenser) to transmit temperature of various zones likely to air bind, so he knows the current state of any fouling. This stuff will not take care of itself, but with all due diligence, perhaps they can turn this situation around, and make a profit.

One other thing: OP needs to question the type of metallurgy present in the tube bundles if "punctures" are taking place. It could be (he did not state) that they have carbon steel tubes, in which case, corrosion thinning may be the culprit, if soft copper alloy, then perhaps erosion from sand/stuck debris in the lee behind the debris. Other mechanisms exist including corrosive pH values present in under-deposit corrosion.