We have GE 9EA Gas Turbines with Mark IV control system. One GT on Gas FSR is 70% at base load and on LFO FSR is 64% at base load. Could any one tell me how to make both FSR same? Give me what is the basis for calculation & details procedure and explanation.

If somebody help it will be a great help.

 

The discrepancy you are reporting between FSRs doesn't seem too bad, are you having trouble transferring fuels without load swings?

Are you trying to transfer fuels at Base Load?

Is your machine equipped with DLN-I combustors?

The purpose of fuel-matching is to reduce transient load changes during fuel transfers while the unit is running. Fuel transfers are risky at Base Load even if fuels are propely matched, so if you're trying to match fuels to perform fuel transfers at Base Load, be prepared for some disappointment (as in, emergency shutdown (TRIP) from full load!).

If the units have conventional combustors, that is, not DLN (Dry Low NOx combustors), fuel matching is a little easier, and if the units have DLN combustors--well, just foget the concept of bumpless fuel transfers, and don't hold out a lot of hope for any kind of repeatable, stable fuel transfers. (Don't misunderstand, relatively stable fuel transfers CAN be achieved with DLN units, but it takes a lot of "tuning" and a lot of patience, and a fair bit of luck!) And, fuel matching for DLN combustor-equipped units is much more difficult and won't even be attempted to be described here.

The caution one needs to be aware of when matching fuels is that when one makes changes to the fuel system to achieve relatively stable fuel transfers at a particular load, those changes can also have an impact on starting, accelerating, and fuel transfers at other loads.

So, please answer the questions above and describe your unit and your operating conditions.

If you have the GE Control Specifications which usually were provided with most Mk IVs (even those not packaged by GE) you should have at least the minimum instructions most TAs (Technical Advisors/Field Engineers) used to base their procedures on. Most TAs developed their own procedures over the years from those basic instructions.

markvguy

 

No we do not try to transfer at base load. But when unit at base load on NG then low fuel pressure can cause to transfer to LFO.

No it is conventional combustor.

I have checked the documentation but i did not find anywhere how to match the fuel.

I would be appreciate you if kindly precisely tell how to match it both ?

thanks

Anonymous

 

Conventional combustors; problems with gas fuel supply pressure.

How often does gas fuel supply pressure drop low enough to initiate a transfer?

What happens during- and after the transfer? Does the unit stay on-line but stabilizes below Base Load after the transfer?

As was said before, transferring fuels at Base Load is NOT a good idea--whether or not the transfer is initiated manually or automatically.

With the FSR values you provided, you have the good situation. At the end of a successful transfer (which you haven't confirmed happening) the unit should be below Base Load, and all the operator has to do is re-select Base Load to load the unit back to exhaust temperature control, Were the FSRs opposite of what you described, the unit would probably trip or at least go into overtemperature alarm during the transfer.

The 'Control Specification-Control System Adjustment' document should describe (probably somewhere in Sect. 5) a procedure for matching fuels. It involves making adjustments to the flow divider feedback scaling--but BEWARE, this should NOT be done with the unit running, AND, changes to the scaling will affect starting and acceleration--not just Base Load operation.

markvguy

 

Very often gas fuel pressure drop low enough to initiate a transfer.

Could you explain please how flow divider scaling can change? and how it will affect in the starting & acceleration? I do not want any warning. I need a procedure with explanation. If you can help me, help me, otherwise no bla bla advice.
Thanks.

anonymous