GE FRAME 9E GAS TO LDO FUEL CHANGEOVER , SOLINOID 20PL-1 DEENERGIZE TIMING AFTER OPERATOR COMMAND INITIATE.

Dear CSA our expert of GE 9E,

I have a question , we have DLN 2.1 Gas Turbine always we face issue after fuel mode changeover . I go through all trends of fuel mode changeover gas to liquid at 20 mw.

Total fuel changeover full time 1 min 2 sec (almost 15 changeover reviewed)

we changeover fuel GAS to LDO , as we observe on trend 20PL-1 this de-energize after 30 sec of operator command .why immediately 20PL-1 don't de-energize and its sub valve VA19-1 also 30 sec active .

due to this issue after changeover successful we have leakage on false start drain pit on primary fuel oil purge valves .
 
Please be more specific about the amount of "leakage" and the duration of the "leakage."

On your system, is liquid fuel flowing from the high-pressure liquid fuel pump BEFORE 20LPL-1 is de-energized?

Finally, on your system is 20PL-1 a NO (Normally Open) or NC (Normally Closed) valve? And is 20PL-1 NC or NO? (This information should be easily visible on the liquid fuel purge P&ID.)
 
One more question--just to satisfy the curiosity of a few of us: Are you sure the unit has DLN 2.1 combustors?

I ask because for a couple of decades GE B/E-class machines only were sold with DLN-I combustion systems. It wouldn't surprise me in the least if GE (specifically, GE Belfort) had a science project to put DLN 2.x combustors on an B/E-class machine. Or, perhaps another vendor has designed and sold DLN 2.x combustors for B/E class machines.

So, if you could clarify the DLN combustion system on the unit at your site and who provided the combustion system, the curiosity of many people would be satisfied.

Thanks very much!!!

Oh--and if you can please attach a copy of the liquid fuel purge P&ID it would be very helpful!
 
The general sequence of events for a liquid-to-gas fuel transfer is that when the transfer is initiated the liquid fuel forwarding pumps are started and the stop valve at that skid is opened (usually 20FD-1). This is to fill the lines up to the liquid fuel stop valve, because many times fuel drains back towards the storage tank and air gets in the piping (from many different possible ways). This usually lasts about 30 seconds or so, then the liquid fuel stop valve, VS1-1 is opened(by energizing 20FL-1) and forwarding (supply) pressure pushes the fuel to the high-pressure liquid fuel pump and around the fuel pump (through the Liquid Fuel Bypass Valve (which is normally open and closes to force fuel to the turbine) and through the liquid fuel flow divider all the way to the liquid fuel check valves (which usually require 100 psig or slightly more to open and allow fuel to through through them to the fuel nozzles--but since forwarding (supply) pressure is around 60 psig (usually) it can't get through the liquid fuel check valves).

The liquid fuel purge line, which if I remember is one of the ports of VA19-1, has to be de-pressurized BEFORE the liquid fuel stop valve opens and fuel can flow up to the liquid fuel check valves. There is a check valve at the fuel nozzle to prevent liquid fuel from flowing backwards through the purge check valve, through VA19-1, and to the gas turbine drains tank (pit). So, it would seem to me that VA19-1 has to change state BEFORE or possibly at the same time as the 20FL-1 is energized (to open the liquid fuel stop valve, VS1-1).

When VA19-1 is blocking purge air flow to the liquid fuel lines/nozzles, it will allow any leakage (in the reverse direction) from the purge check valves to flow through the Tell-Tale Leakoff to the gas turbine drains tank (pit). It could be possible that one or more of the purge check valves is leaking in the reverse direction, if not fully leaking all the time, then leaking a small amount for a short period of time--but still leaking.

That's why it's important to understand how much liquid fuel (an estimate is all you can provide) you are seeing coming out of the Tell-Tale Leakoff (directed to the gas turbine drains tank (pit)), and for how long you are seeing flow. If it's not very much (a liter or two), and it only last for 20-45 seconds or so, that's not bad--but it could indicate an impending purge check valve failure that could be serious.

If the flow through the Tell-Tale Leakoff is 20 liters or more for several minutes--but it does finally decrease to a trickle (very small flow), then it, again, sounds like a purge check valve is leaking in the reverse direction, a lot in the beginning, but it does finally shut off.

If it's a large flow that doesn't stop, that's a leaking purge check valve that's going to result in/cause high exhaust temperature spreads when running on liquid fuel.

So, it should be clear--VA19-1 should move to the position to shut off purge air flow to the liquid fuel lines/nozzles BEFORE liquid fuel gets up to the liquid fuel check valves. There may be a timing issue, but I don't quite see how. The idea is NOT to get any liquid fuel into the purge air system, and purge air pressure should be well above liquid fuel forwarding (supply) pressure so even if VA19-1 didn't change state soon enough AND there was leakage through one or more purge check valves the purge air pressure should push the liquid fuel into the fuel nozzles (which isn't good either, but it's better than getting into the purge air system).

It could be that VA19-1 isn't changing state fast enough--but even then, purge air pressure is higher than forwarding (supply) pressure. And it would still imply some leakage through one or more purge check valves. Or 20PL-1 isn't bleeding air pressure off the actuator of VA19-1--but still, it implies some leakage through one or more purge check valves.

All of this is WITHOUT being able to see the Liquid Fuel Purge P&ID (and the Liquid Fuel System P&ID), and it presumes GE Belfort or some other supplier hasn't modified the logic which has been in place on GE-design heavy duty gas turbines for decades. And, it presumes the use of spring-loaded, poppet-style check valves--and it's my understanding that GE and its packagers are moving away from those and towards air-operated valves for purge air lines and false start drain valves, etc.

Hope this helps!
 
Good Afternoon dear CSA,

Almost 5 years we startup power plant , as my past feedback , never maintenance perform PM of VA19-1 .the operating pressure for VA19-1 around 3.2 bar. I think need PM for this valve as well.

CSA we have GE Belfort machine . Are you remember previous two week I ask one thread regarding evaporative cooler as well , I change my ID due to some professional reasons . I face same issue due to this user name by my real name.

I attached the images below of VA19-1 and 20PL-1.

In my current work place , whenever we plan for changeover at least before 6 hours we start forwarding pump .
when machine on 20MW , we told I&C open 20FD-1 for prime all fuel line before VS1-1 ,we preform this for minimize the trips and also minimize the fluctuations during fuel mode changeover .

when all is done we unforce 20fd-1 (fuel line is pressurize before VS1.

operator initiate command for fuel mode changeover GAS to LDO .as per trend First open 20fd-1 and then open VS1 and in the same time VC3 also try to close/open.

As you know VC3 reverse work , its fully open but during changeover oscillate 0% to 10% , after 30 sec 20pl-1 deenergize and vc3 stable as well then gradually GCV V/V CLOSE AND FUEL V/V INCRESSE OPEN.
 

Attachments

one more thing CSA , this 4 to 5 time oscillate VC3 ON 20 MW , I remember once i was a CCR same machine i performed changeover fuel Gas to LDO , I was initiated command at 40MW .

I observed only 2 times VC3 oscillate, is fuel mode changeover is more efficient on more load?
 
CSA as my question must be VS1 Whenever open directly purge air v/v need to close am i right? if its take 30 sec , so make trouble for remain open few purge check v/v at LDO fuel oil lines.
 
yes absolutely CSA we have spread issue many time as i remember last week we have one trip on spread as well. i share some stuff related recent trip on spread.

we have machine trip on baseload at LDO fuel due to electrical issue . after we start on gas and same at 20MW changeover GAS to LDO.

same time we saw 20pl-1 is close but when we increase load gradually there is some pressure after 20pl-1 line its means fuel purge v/v leakage and same time spread also increasing and nearly when we stop increasing load at 90MW SPREAD LIMIT,TTXPL GRADUALLY DECREASE and when reaches spread TTXSP1+ TTXSP2 =TTXPL machine trip.

i saw trend when spread increase same time after 20pl-1 line pressure is around 4 bar , so its means heavy fuel return FSD PIT via fuel purge check v/v.

we change all primary fuel purge check v/v and install new fuel purge check v/v but when again start , we have same leakage on FSD pit , we trace line its coming from primary fuel purge check v/v.

CSA IS AM I RIGHT after VS1-1 open during fuel changeover , must be 20PL-1 close immediately, same time how its possible we inject fuel and we inject purge air around 30 sec .
 
ECS 9E,

I have had trouble reading and interpreting you posts--all of them, before and now.

You seem to purposely neglect responding to direct questions--such as how much flow do you see coming from the Tell-Tale Leakoff (the pipe from VA19-1 that drains into the gas turbine/oily waste tank (pit)? Is it because you can't quantify how much (in liters, for example) because the flow is too high, or because it's too low, or what? Or, how long the flow lasts?

It's NOT enough to just start the forwarding pumps by forcing the logic (everyone's FAVORITE thing to do!) and letting the pump run. Vents need to be opened slightly and any air needs to be allowed to exit the piping and any filter canisters until a steady flow of liquid fuel comes out of the vent (with no bubbles). Any transfer fill valves on duplex filter assemblies need to be put in the proper position. If there are (and there should be) high-point vents in the liquid fuel supply piping between the forwarding pumps and VS1-1, they should be opened to bleed out any air.

Common sense would say: If there's fuel flowing out of the VA19-1--a LOT of fuel--then one or more purge check valves is/are not preventing the back-flow of fuel through the valve(s). Unfortunately I can't see the P&ID very well on my phone (I'm traveling) so I can't tell what the configuration is. The fact remains: Regardless of the pressure on the liquid fuel side of the purge check valve (forwarding/supply pressure, or high-pressure liquid fuel pump discharge pressure) the check valve should prevent liquid fuel from flowing in the reverse direction through the check valve. That liquid fuel MUST go to the fuel nozzle, or there will be higher than normal exhaust temperature spreads. Full stop. Period.

Does it make any difference what time or when VA19-1 stops purge air from flowing into/through the purge check valve and into the fuel nozzle? Not if purge air pressure is higher than fuel pressure. Should purge air be flowing into the fuel nozzle when trying to transfer to liquid fuel? No.

As for when to transfer fuels (load-wise), the higher the load the better--that doesn't mean it should be done at Base Load, but higher than 20 MW is probably better than 20 MW. The USUAL cause of instability during a fuel changeover/transfer from gas to liquid fuel is air in the lines. Full stop. Period. The reason the flow divider feedback is unstable during fuel changeover/transfer is almost always because of air in the lines. The liquid fuel bypass valve will VERY QUICKLY change position to try to maintain a stable flow of fuel, so that shouldn't be a surprise. If the total amount of fuel flow is low (because the load is "low") then it's going to be harder to establish stable fuel flow if there is air in the line. GE sells some VERY EXPENSIVE systems designed to prevent air from getting into the liquid fuel supply piping (which is very difficult to do). And, if the site that is paying you is only turning on the forwarding pumps for a few hours prior to a changeover/transfer and not venting the lines to remove air or be sure there is no air, then they're wasting electricity. And, the forwarding pumps are probably getting very hot, too.

That's ALL I'm going to say on this thread. Full Stop. Period.
 
Good evening,

Dear CSA, JUST DURING TRIP TIME TO MUCH FUEL FLOW ON FSD pit and we drian two times sump tank after every 3 hours by vaccum pump.

But after we change all primary check valves then startup on LDO, now its reduce fuel flow, we can say 5 liters in one hours it's my calculation.

This 5 liters / hour on FSD drian after replacement of all primary check valves.
 
Dear CSA, we perform venting as well but before VS1 stop valve after VS1 we have duplex filter this we perform vent while open on auto during chengeover time.
We prtailly open HP filter vent and we partially open fuel pump vent as well.

But both these we perfome venting during Changeover.

Because if machine already running on gas fuel if we open forcly VS1 stop valve for priming HP filters and pump its may cause intrup operation so we no doing before only during chnageover time we do.
 
Dear CSA, we perform venting as well but before VS1 stop valve after VS1 we have duplex filter this we perform vent while open on auto during chengeover time.
We prtailly open HP filter vent and we partially open fuel pump vent as well.

But both these we perfome venting during Changeover.

Because if machine already running on gas fuel if we open forcly VS1 stop valve for priming HP filters and pump its may cause intrup operation so we no doing before only during chnageover time we do.
ECS 9E

You sollicated me by asking me help/advise in PrivateMessgae , and now you even don't reply to my last message...
Thats's not so professionnal ...
I could add some help on this thread but you showed me no respect, by at least not ever replying..

ControlsGuy25.
 
ECS 9E

You sollicated me by asking me help/advise in PrivateMessgae , and now you even don't reply to my last message...
Thats's not so professionnal ...
I could add some help on this thread but you showed me no respect, by at least not ever replying..

Thats second time that a Technician/engineer asked me for help then go away without coming back to me with response to my message... Now i have experience to not help too much people here because of this kind of behaviour...

I dont like such behaviour thats opposite to sharing /learning from each other on this wonderful world of power generation...




ControlsGuy25.
 
Dear brother control guy ,

you are very good person and supportive.
Thanks for help bro

I try to solve this issue which I was ask but unfortunately bro it’s remain same , so I withdraw this situation .

hope and wish all going great
God bless u
 
Dear brother control guy ,

you are very good person and supportive.
Thanks for help bro

I try to solve this issue which I was ask but unfortunately bro it’s remain same , so I withdraw this situation .

hope and wish all going great
God bless u
Dear brother Ecs9e,

Thanks for your answer. That's much appreciated...
You are a very good personn....too....
I could try to support on the other thread.... But it's okay if you removed it...

We will discuss and learn better on any issue in future...

Iam not bad.. Thank you..
I wish you the best for this year..
God bless you..
Controls guy25.
 
Awwwwww....

What a sweet bro-mance we are witnessing here.

[That was too hard to resist.]

:oops:
Well,
I don't think that's a bromance..
That's just that I wanted to clarify my position with people who asking help and support on this forum.. Since I know that some people are just coming here with sometimes intention to get what they need and leave forum without giving feedback on the.. "issue solution"
BTW that's not forbidden to shares with people around the world.. some good words sometimes.. It is involved in good relationships...

A bon entendeur,

☺
 
CSA our inspiration,

really we don't know perfectly anything , but I mention you CSA , we learn a lot of thing from your expert feedback .

and CSA I am not put butter , we all really appreciate your immediate respond for solve other problems .

GOD bless you to always !
 
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