Hi,

I need the experience of customers who own the GT MS3002 J GENERAL ELECTRIC with a new retrofit of the electric fuel valve.

I want to know that we got the GT FRAME 3 MS3002 since decade 1970 RUNNING better mechanically with the old valve SRV GCV on the same bloc. Now if we want to retrofit the fuel valve with the new electric valve is better (woodward valve).
Thanks for any users help.

 

Hi,

I AM ALWAYS WAITING HELP FROM MORE GT GE MS3002J USERS.

My email is dameneamar [at] yahoo.fr

Thanks

 

Most people want to replace electro-hydraulic servo-valves and hydraulic actuators because they have experienced lots of problems with either the servos or the actuators, or both. Most of those problems are self-inflicted, because of poor L.O. maintenance practices. In recent years, the oil companies have contributed to the problem because they have changed the turbine L.O. formulations which has actually resulted in more servo problems than with the old formulations.

Electric gas control valves have their own problems. First, the gas flowing through them must be pretty clean and free of abrasives and liquids, especially sticky liquids which can condense when passing through a control valve.

Usually when GE installs an electric gas control valve, the single valve replaces both the SRV and GCV, which saves on the maintenance for two valves, two servos, and two actuators, and LVDTs, etc. But, they also usually require that two stop valves and a bleed valve, in a double-block-and-bleed arrangement, be installed upstream of the electric gas control valve. And these have their own maintenance requirements, and actuator requirements (compressed air or gas supply), and associated solenoids, limit switches, etc.

So, unless you've been having problems with electro-hydraulic servo-valves failing (not because of L.O. issues), or failing actuators, or leaky gas valve assemblies, or other issues, and unless you can ensure your gas fuel supply is clean and dry, then why change? You seem to be saying that you've had good luck for decades with the existing arrangement; why mess with a good thing? You would have to change a lot of piping, including eliminating the trip oil and hydraulic supplies and drains, and install new components and conduit and wiring. It's *NOT* just a "plug-and-play" change-out! And, there's the necessary control system modifications, as well, to drive and control the valve.

Some sites swear the electric gas control valves are better than the hydraulic SRV/GCV. Others, swear at the people who purchased them, because they've been a big headache since they were installed. And, again, mostly because of gas fuel supply problems causing sticking and erosion of the internals of the electric gas control valve. Some sites have had to install separators and coalescing filters and all manner of upstream "treatment" to keep the electric gas valves from seizing or passing.

Hope this helps!

 

Thanks more CSA.

Do you know why I am waiting more help from GT GE MS3002J users because we got a big problem.

We did a retrofit upgrade Speedtronic Mark II to Mark VI for many GT GE MS3002J.

Before these GT are runing with SRV GCV valves and ok no problemes. AFTER retrofit we changed Mark II to Mark VI and we changed the SRV GCV by an electric valve.

After many hours we find many mechanic problems inside the GT. THE BLADES AND THE MORE BIGS PARTS. BROKEN WEAR it concluded that was high temperature inside and demaged more parts.

We cannot run the GT Now.

WE ARE searching the cause of the problem. In another site we did not change the SRV GCV and no problems.

Thanks for anu help. f anyone wants to see pictures please send your email.

 

Damene,

Whoa there! You say it has been determined ... By whom was it determined? And how was it determined?

What does the supplier of the control system and the electric gas valve have to say about this?

How long has the unit been running with the new turbine control system and the electric gas valve?

If this is a recent upgrade, what other work was done to the turbine when the control system and fuel valve were being replaced?

Do you have fuel flow-rate data from before and after the change to compare to see what the difference might be?

Was the unit producing more torque/flow than prior to the changes? Significantly? More than might be attributed to just a new control system or a turbine upgrade? Because for there to be internal damage of the type you describe, it would seem that a lot of extra fuel (more than previously) had to be flowing. Or there was some kind of problem in the hot gas path or exhaust.

What other work has been done to the turbine since the control system and fuel valve were replaced?

The fuel valve (electric <b>or</b> hydraulic) is only going to put as much fuel in the unit as the CPD-biased exhaust temperature control will allow.

It's been a very long time since I've worked on a Frame 3 two-shaft machine, but as I recall the fundamentals of exhaust temperature control are the same as for a single-shaft heavy duty gas turbine. So, my comments below presume my recollection is correct.

Was the unit running on CPD-biased exhaust temperature control?

Changing the type of fuel valve from hydraulic to electric shouldn't have resulted in a change in the way the exhaust temperature is being controlled. And, remember: CPD-biased exhaust temperature control is really "firing" temperature control. And "firing" temperature is the temperature of the gases flowing through the first stage turbine nozzle.

So, "exhaust temperature control" is really internal combustion gas temperature control, presuming all of the inputs to the Speedtronic are working correctly, that the inputs are configured correctly, and that the exhaust temperature control parameters were properly programmed.

If the exhaust temperature control is not configured properly, or the exhaust T/Cs are not configured properly, or the CPD feedback is not configured properly, or the exhaust temperature control parameters are not correct then fuel valve (electric <b>or</b> hydraulic) isn't going to work properly.

If the Speedtronic thinks the exhaust temperature is 500 deg C and it's actually 600 deg C, and the exhaust temperature limit is 500 deg C, the fuel valve (electric <b>or</b> hydraulic) is going to be adjusted to allow as much fuel as can be flowing to make the exhaust temperature feedback equal to the exhaust temperature reference. In this case, if the feedback is lower than the actual temperature, then too much fuel is flowing.

(Even if the unit isn't running on exhaust temperature control, the exhaust temperature control "limit" is always active.)

Or, if the CPD transmitter is not calibrated properly or the feedback isn't scaled properly and the exhaust temperature limit is higher than it should be, then the fuel valve will admit too much fuel.

But, the <b>type</b> of fuel valve isn't going to make a bit of difference to the amount of fuel that's flowing versus the exhaust temperature control limit, which is constantly being calculated, even when the unit isn't running! (There I go, using the exclamation point. I need to be careful about that, don't I?)

So, determination being what it might be by whomever might have made it, the type of fuel valve (electric <b>or</b> hydraulic) shouldn't be the culprit. Even if the fuel valve wasn't working correctly, all it's doing is controlling the amount of fuel that's flowing into the turbine. And the amount of fuel is usually pretty proportional to the exhaust temperature, so too much fuel will cause too much exhaust temperature, except when the exhaust temperature feedback isn't correct, or the exhaust temperature limit isn't being calculated correctly, or something like that is causing either the actual exhaust temperature or the exhaust temperature limit not to be correct.

But the <b>type</b> of fuel valve causing excessive firing temperatures? I think not very likely.

Of course, if the control system isn't using CPD-biased exhaust temperature control, then the above is not correct. But there should be some "limit" that protects the turbine from "overfiring" and causing the kind of damage you are saying has occurred. Protecting against over-firing is so key to the protection philosophy for GE-design heavy duty gas turbines that I would think there is some kind of limit to prevent internal combustion gas temperatures from exceeding the appropriate limit, even if it's not the "traditional" legacy CPD-biased exhaust temperature control used on most GE-design heavy duty gas turbines.

Again, what has the supplier of the control system and gas valve said about this problem?

I don't think a lot of two-shaft users hang out here on control.com. They should; but they don't seem to.

It would be really great if you would continue to provide feedback about the discoveries and resolution to this situation now that you have made it public.

 

Damene,

Further to this, you say you have upgraded *many* units to Mark VI and electric gas control valves. And, yet, only this one unit has had a problem?

There are lots of electric gas control valves in service around the world, and per your own description, multiple valves on units you work with and support. So, why just this one is having problems?

This time, I am anxiously awaiting much more detailed information.