liquid fuel nozzle purge air check valve

GE frame 9 E DLN1 system every time we have liquid fuel nozzle purge air check valve leakage fuel leak from tell-tale leak off and need to replace it, we suspect the liquid fuel and water purge air heat exchanger not work properly please we have any temp. sensor on the purge air if not how we can check it
 
GE frame 9 E DLN1 system every time we have liquid fuel nozzle purge air check valve leakage fuel leak from tell-tale leak off and need to replace it, we suspect the liquid fuel and water purge air heat exchanger not work properly please we have any temp. sensor on the purge air if not how we can check it
A P&ID or drawing at least woul be greatly welcome ....
 
Yes, the P&ID for the purge and cooling water systems would be very necessary to understand what might be happening.

Over the decades, the check valves GE has used for the liquid fuel, liquid fuel purge and water injection purge systems have been problematic. Especially the poppet-style check valves (spring-loaded) which have small o-rings inside them. And especially for units which burn both natural gas and liquid fuels, and even more especially for those units which burn natural gas primarily and only burn liquid fuel occasionally.

Personally, I have never seen a liquid fuel or water injection purge system with a heat exchanger in it--I presume it would be to cool the air before it enters the check valve and the fuel nozzle/combustor--but that's a presumption. GE Belfort does a LOT of things which have never been done before (and will never be done again) just because they can. And, in the process they also manage to grossly over-complicate just about anything they touch. So, I imagine the addition of a "pre-cooler" heat exchanger in the purge air system is something which they are thinking will help to possibly reduce check valve failures.

Historically, the purge check valve failure mode has been because of pressure pulsations in the air supply to the check valve which cause the springs being compressed when purge air is flowing through the check valves to allow the poppets to move back and forth, even slightly, which causes excessive wear on the poppet, the internal of the check valve assembly, and can also sometimes result in unseating the o-rings.

One thing which has been done with a good deal of success is to replace the spring-loaded, poppet-style check valves with pneumatically-operated valves which are either open or closed. Solenoids, controlled by the Mark* are used to control the air flow to the valve actuators to open and close them. The valve internals are usually ball-like and can only rotate 90 degrees open or closed. While this eliminates the wear of the poppets and check valve internals and some of the damage to the o-rings caused by purge air pressure pulsations--it GREATLY increases the amount of tubing and tubing fittings/connections in the turbine compartment. And, if the units have DLN-I combustors with water injection and atomizing air the turbine compartment is already pretty crowded.

The spring-loaded, poppet-style check valves are "nice" because they don't require any motive force (air pressure) and they don't require anything in the way of turbine controls. They are simple check valves which open or close depending on pressure differential, and they are simple to install/replace in the purge air lines (unless the unit is a dual-fuel DLN-I combustor-equipped unit). And, they are inexpensive. Pneumatically-operated check valves (I wouldn't technically call them check valves--they are really just open/close valves) are much more complicated, and most maintenance managers and mechanics despise removing and re-installing them during maintenance outages.

There is a US company, JASC, which has been making some very reliable designs of check valves over the years and a lot of sites have used them with good results.

So, there you have a short history of a long problem (failing and unreliable check valves--though the amount of time the valves have purge air flowing through them is a factor in their longevity, too).

If there aren't temperature sensors (T/Cs) installed on the air inlet and air outlet of a purge air heat exchanger, you are certainly free to install them. For test purposes I have quite often just made my own T/C (using T/C extension wire, stripping a couple of cm of insulation off the ends, twisting the conductors together and then "bonding" them together with a ball peen hammer and a vise (smashing the twisted ends together)). Then I just use some fiberglass electrical tape to hold the newly-created T/C tip to the pipe, sometimes I use a hose-clamp over the outside of the fiberglass tape to keep the T/C in place. You can use a multi-meter or T/C tester to watch temperatures and have someone periodically record the temperatures, or you can have someone connect them to spare Mark* T/C input channels (though these days, that's a LOT more involved than it used to be--especially if you want to add the values to a HMI display--which EVERYONE wants to do....).

Hope this helps! Please write back to let us know what you do and how it turns out. And, if you do write back for more help, please attach copies of the relevant P&IDs for more help. We have NO IDEA what GE Belfort does or doesn't do, and they are consistently inconsistent along with being prone to overly complicate most anything they touch. So, at this point, without P&IDs, we are just speculating. But, at least you have an understanding of the decades-long history of purge check valves on GE-design heavy duty gas turbines.

Best of luck!
 
Hi

Thanks for sharing P&IDs...

Where the leakage is located ( primary /secondary ...)

What DP transmitter readings are ( are they correct as per Vendor recommandations values...)

Is that both (primary /secondary ) Liquid fuel purge air valve are operating correctly...

James
 
aras.ali,

Well, the packager is, indeed, GE Belfort. So, one question answered.

And, WOW!!! Water-cooled liquid fuel check valves IN ADDITION to purge air cooling!!! Must be a pipefitters'/mechanics' nightmare working on that unit's turbine!!!

You were given some ideas for temporarily installing T/Cs on the inlet- and outlet air piping from the purge air heat exchanger, which was your original question. The only decision you have to make now is: How are you going to monitor the feedback from the T/Cs?

From what is visible on the P&IDs, there is NO temperature control on the purge air heat exchanger; as long as the manual cooling water isolation valves on the inlet- and outlet lines to/from the heat exchanger are open AND the heat exchanger is not plugged or dirty on the cooling water side, the heat exchanger should be working. Unless it's undersized--and you should have some documentation from GE Belfort (HAH!!!) to say what the desired maximum purge air temperature should be. (One has to wonder if the problem might be excessive cooling, causing condensate to form in the purge air tubing and thermal stresses on the check valve...??? So, a good question for GE Belfort would also be: What is the minimum allowable purge air temperature???)

But, the only way to tell for sure is to install some kind of temperature measuring devices and monitor them to tell how well it's working. And, you have some suggestions for that--again, you just need to decide how to monitor whatever type of sensor you decide to install. You may find some thermowells in the purge air inlet- and outlet piping of the heat exchanger which you could use to install T/Cs or RTDs. But, if it's only a temporary measurement you want, just firmly attaching them to the outside of the piping is going to give you a good relative measurement (presuming there's no nearby fan that is going to distort the readings from one side or the other (inlet or outlet)).

Best of luck! Please write back to let us know what you discover!

[Honestly, this is a HUGE oversight on GE Belfort's part--a huge missed opportunity to add additional instrumentation, conduit, wiring and control signals and possibly some kind of purge air temperature regulating valve (maybe even hydraulically- or electrically operated)--thereby increasing the complexity of the control scheme as well as the ability to work on the purge air heat exchanger. And, screw up the application code by making it needlessly complex and obtuse to anyone trying to understand it. A real missed opportunity.... It's SO uncharacteristic of them to NOT try to control every aspect of operation. AND, add some cryptic Process Alarm messages, too!!!]
 
Hi

Thanks for sharing P&IDs...

Where the leakage is located ( primary /secondary ...)

What DP transmitter readings are ( are they correct as per Vendor recommandations values...)

Is that both (primary /secondary ) Liquid fuel purge air valve are operating correctly...

James

Dear James
the leak most coming from primary and some time secondary , DP transmitter readings you main that on Y filter FA104 I will check it and replay
 
Dear James
the leak most coming from primary and some time secondary , DP transmitter readings you main that on Y filter FA104 I will check it and replay
Dear Aras.ali

Yes that DP transmitter on Y filter FA104.I

Check also all DP transmitter readings and see if they are in accordance with OEM recommandations.

What about the liquid fuel purge air control Valve
 
Dear James
the leak most coming from primary and some time secondary , DP transmitter readings you main that on Y filter FA104 I will check it and replay
Dear CSA thanks for this information's I will Ask GE about maximum purge air temperature should be and I try to Measurement it (I don't worry about minimum I am in iraq and the weather is very hot )
 
Aren't the liquid fuel purge "control" valves three-way valves--WITH limit switches to indicate position?

The "cone" strainers (witches' hat strainers) don't have dp switches or gauges; they could be plugged (choked)....

AND, if GE Belfort installed dp transmitters and/or gauges on the system, they CERTAINLY have multiple cryptic Process Alarm messages to indicate a problem (OH--and they also use Process ALARMs to indicate when something is working as it should, too!).

Which brings up the question which should have been asked much earlier: What liquid fuel-related Process Alarms are being annunciated by the Mark*??!!?!?

Finally, you say you have been replacing liquid fuel purge check valves. What kind of inspection/analysis of the failed check valves have you performed--and what do the results indicate the failure mode is or might be? Is this why you suspect purge air temperature to be the cause of the check valve failures?
 
One more thing, it's interesting the liquid fuel check valves are water-cooled, but the purge check valves are not.... Aren't they in the same turbine compartment--meaning don't they experience the same temperatures in the turbine compartment? Is the liquid fuel heated?
 
Dear Aras.ali

Yes that DP transmitter on Y filter FA104.I

Check also all DP transmitter readings and see if they are in accordance with OEM recommandations.

What about the liquid fuel purge air control Valve
Dear
liquid fuel purge air control Valve checked it (we started 88AB and forced 20PL-1&20PL-1 both valves(VA19-1&VA19-2) checked fiscally it was full open and air flow in both primary and secondary after disconnected tubes
 
Aren't the liquid fuel purge "control" valves three-way valves--WITH limit switches to indicate position?

The "cone" strainers (witches' hat strainers) don't have dp switches or gauges; they could be plugged (choked)....

AND, if GE Belfort installed dp transmitters and/or gauges on the system, they CERTAINLY have multiple cryptic Process Alarm messages to indicate a problem (OH--and they also use Process ALARMs to indicate when something is working as it should, too!).

Which brings up the question which should have been asked much earlier: What liquid fuel-related Process Alarms are being annunciated by the Mark*??!!?!?

Finally, you say you have been replacing liquid fuel purge check valves. What kind of inspection/analysis of the failed check valves have you performed--and what do the results indicate the failure mode is or might be? Is this why you suspect purge air temperature to be the cause of the check valve failures?
Dear CSA the check valves inspected found 3to5 of them (14 primary check valves) it was stuck opened with like carbon partcals in the check valves
 
One more thing, it's interesting the liquid fuel check valves are water-cooled, but the purge check valves are not.... Aren't they in the same turbine compartment--meaning don't they experience the same temperatures in the turbine compartment? Is the liquid fuel heated?
Dear CSA
yes the liquid fuel (LDO) heated to 40C (I don't sure exactly )
 
The heated liquid fuel is ... interesting.

If you found carbon-like particles in the failed check valves, it would be a very good idea to send those particles out to be analyzed to determine where they came from: fuel or ???

When running on liquid fuel there IS liquid fuel in the purge check valve, and if that liquid fuel is carbonizing (hardening) that would seem to be a problem--one that liquid cooled purge check valves might solve....

(Excessive) Heat (in the turbine compartment) is going to cause the liquid fuel to carbonize. In the short bit of tubing between the purge check valve and the fuel nozzle connections there is no flow--the fuel is just sitting there, getting hot.... and carbonizing (hardening).

I wonder what a bit of insulation (a tight roll maybe 5 or 6 cm thick) wrapped around the purge check valve and the tubing connecting it to the fuel nozzle (primary fuel distributor and secondary fuel nozzle) would do to reduce the heat impingement on the check valves and tubing.
 
The heated liquid fuel is ... interesting.

If you found carbon-like particles in the failed check valves, it would be a very good idea to send those particles out to be analyzed to determine where they came from: fuel or ???

When running on liquid fuel there IS liquid fuel in the purge check valve, and if that liquid fuel is carbonizing (hardening) that would seem to be a problem--one that liquid cooled purge check valves might solve....

(Excessive) Heat (in the turbine compartment) is going to cause the liquid fuel to carbonize. In the short bit of tubing between the purge check valve and the fuel nozzle connections there is no flow--the fuel is just sitting there, getting hot.... and carbonizing (hardening).

I wonder what a bit of insulation (a tight roll maybe 5 or 6 cm thick) wrapped around the purge check valve and the tubing connecting it to the fuel nozzle (primary fuel distributor and secondary fuel nozzle) would do to reduce the heat impingement on the check valves and tubing).
Dear CSA
thanks your I will update you after send this particles to lab
Best Regards
Aras
 
aras.ali,

Thanks for your responses and updates; it's very helpful for those contributing to the thread AND to those following it (now and later!).

We look forward to hearing what is learned about the carbon-like particles from the analysis.
 
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