In our gas turbine power plant, fumes always come from the mist eliminator vent. So much that the surrounding area becomes slippery.

The vacuum maintained is around -100mmH2O. The problem with lower vacuum is that lube oil leakage starts from load gear and other points.

Can there be any balancing method to prevent the fumes and leakage both?

Is there any safe method in use anywhere to discharge the fumes?

 

How long has it been since the elements inside the Mist Eliminator vessel were inspected and/or replaced?

Is the loop-seal between the vessel and the L.O. tank filled and working properly? If there's a valve or valves in the loop-seal line are they "locked" in the full open position?

The whole, entire purpose of the <b>Mist Eliminator</b> is to prevent visible plumes from the L.O. tank vent from getting into the atmosphere and contributing to air pollution. In some parts of the world if there is a visible plume seen exiting the Mist Eliminator the plant owners and even the operators can be fined and sent to jail.

So, Mist Eliminators are capable of removing oil droplets from the discharge--if properly maintained. If not (properly maintained) the elements inside can be incapable of absorbing/removing the oil droplets.

Get that fixed, Mate--it's creating a safety hazard as well as contributing to air pollution!

 

Hello Seeker,

we are specialized in oil mist elimination and generating vacuum in the lube oil tank and the bearings. If you are interested, we could have a chat about your problem and try to find a proper solution for your special problem.

Just leave a reply or get in touch with us and refer to me at [email protected]

I am awaiting your message. Have a nice day and best wishes from Germany

Christopher

 

Hi yo'all,

In most cases like this situation a redesign or spec change of your
Tank mist eliminator and vent piping will normally solve this problem
a slippery dripped area.

Peter B Macalua
Port Arthur,TX

 

Hello CSA,

>Is the loop-seal between the vessel and the L.O. tank filled
>and working properly? If there's a valve or valves in the
>loop-seal line are they "locked" in the full open position?

In the line between the vessel and LO tank, there is a box (like a jb) where there is a view glass too. During the current going HGPI, the drain point of the box was opened and oil drained out of it. So it was filled. There is no valve in that return line.
I don't understand why it is called loop seal; if I am pointing to the right part.

The part I am referring is a junction box where oil collects (line LO41) and when it is filled to a particular level, it drains to the LO tank.

Please correct me if i am wrong.
Thank you.

 

Seeker1988,

A loop seal is a means of isolating one body of liquid (possibly with a higher pressure) from another, possibly with a lower pressure. An example of a loop seal is in the bottom of a toilet. There is a "loop" (an S-shaped passage (the S is laying on it's side)), and that loop is filled with water; the water in the S-shaped passage is the seal fluid. It isolates the septic or the sewer system and it's gases (methane; bad-smelling gases) from the room the toilet is located in. Sinks connected to a septic tank or sewer also usually have a loop-seal (sometimes called a P-trap--don't know the derivation of that term!) to prevent septic/sewer gases from coming up from the line below into the room the sink is located in.

A loop-seal is used to prevent the negative pressure in the L.O. Tank (a very slight negative pressure at Base Load, drawn by the Mist Eliminator fan) from creating a suction on the Mist Eliminator pressure vessel. And, it also helps to maintain a "seal" between the Mist Eliminator Tank, and the L.O. Tank, while still allowing "condensed" oil vapors to return to the L.O. Tank automatically. (That's where's not supposed to be a valve in the line between the Mist Eliminator drain and the L.O. Tank--or, if there is one, it should be locked/secured in the open position except during maintenance outages.

I suspect the "JB" you're referring to is used as the loop seal; that's the reason there's a sight glass--to make sure there is some oil (which is the seal fluid) in the "JB" at all times, but that the level is not too high (which would mean oil is not flowing from the Mist Eliminator to the L.O. Reservoir).

Have you examined the cartridges inside the Mist Eliminator vessel yet?

[I used my preferred World Wide Web search engine to find that present day P-traps (plumbing trap) were invented by one Thomas Crapper! I learn so much from answering queries on control.com!!! In any case, a plumbing trap and loop seal are essentially the same things.]

 

Hello CSA,

The cartridge of the mist eliminator has been replaced during the ongoing HGPI.

Thanks for the explaining the loop seal. If the JB is the loop seal, then there must be an S-loop inside which i am not confirm. The maintenance department showed inability to open the JB as one end of the outgoing pipeline (To MOT) is welded.

 

Seeker1988,

So, the internals were replaced during an on-going HGPI (which is happening now), which probably means you don't know if the Mist Eliminator is working properly or not yet. Is that correct?

Has the Mist Eliminator ever worked correctly? Because if it did for a long time, and then over time gradually started "puking" oil improperly, then it's very likely replacing the internal elements will solve puking the problem.

If it's never worked correctly, then it could possibly be the "loop seal", or some flow restriction in the line between the Mist Eliminator and the L.O. Reservoir.

 

CSA,

The performance of the mist eliminator will be checked when the machine is started after HGPI. Only thing left now is the flushing of line between the vessel and oil tank. I have asked the HGPI in-charge for the same. What method would you suggest for removing the restriction in that line?

I really want the issue to be solved.

 

Hello CSA,

The machine has been running for a week now and no fumes are coming out of the mist eliminator vent. We had flushed the vent line, changed the filters and the loop seal was checked and oil was filled before boxing up.

 

Seeker1988,

Thanks <b>VERY MUCH</b> for the feedback!