We have 01 GT Fram-6 machine controlled with Mark-IV for combined cycle PP.Being a mechanical guy i am not familiar with elementary drawing & logics.

Pls anybody explain or provide idea about IGV auto & Manual & Temp control on & off.

Can we put IGV in Manual mode & Temp Control ON
at a time.
Also IGV in Auto mode & Temp control OFF at a time.

Regards

 

IGV Temp Control is primarily a means for maximizing exhaust temperature at part load (i.e., loads below Base Load, which can only occur when the IGVs are fully open).

If the unit is combined cycle without a bypass stack then chances are it should be operated with IGV Temp Control enabled and active when the unit is below Base Load so as to maximize steam production.

Manual IGV Control allows an operator to close the IGVs (when the unit is operating) below the current reference, usually only for testing purposes. But there is a limit to how far they can be closed,which is the CPD-biased Exhaust Temp Control limit. It's not normal to use IGV Manual Control when IGV Temp Control is active.

Hope this helps!

 

It is used for steam to metal temperature matching for a cold start on the steam turbine. This to minimize steam turbine fatigue, rubs and vibration on start up, a nd predominately determine by the bowl temperature. In this mode GT exhaust is control at less than maximum, and typically setpoint for 200F above steam turbine metal temperature. Once steam turbine has started exhaust temperature is maximised by part load IGV control curve.

 

Thanks for your reply. I will study this further & come back if have any query.

Regards

 

This particular use of IGV Temperature Control is called "Temperature Matching."

Temperature Matching is typically only supplied on combined cycle applications where the plant is cycled on and off each day, sometimes more than once per day. As you say, it's used to try to help match steam temperature to metal temperature to avoid long waits (sometimes referred to as "holds") to get the unit up to rated load.

 

I would like to add further to what CSA has said:

In case of Frame VI machine (cause thats what i operate), when IGV temperature control OFF, IGV will start opening from minimum opening of 57 degrees when the exhaust temperature reaches 360 degC till full opening (86 degress) so as to maitain an exhaust temperature of 360 degC. Once IGV has reached its maximum opening then exhaust temperature will start increasing it reaches CPD biased exhaust temperature limit ie:- when firing temperature (calculated using CPD and exhaust temperature TTXM) reaches its maximum allowable limit. At this point FSRT becomes min and controls FSR.

In IGV temp control ON, IGV opening remains at min opening of 57degrees till exhaust temperature reference is reached, TTRXGV which I guess is 566degC in some machines and in others 580degC.Thereafter IGV starts opening untill maximum limit and there after base load is reached and FSRT takes control.
I hope this helps

 

Yes, this is a "feature" of most GE-design heavy duty gas turbine control systems on conventional combustor-equipped machines.

It can be very confusing to operators and technicians because they will see the Status Field Message "IGV Temp Control" during the loading, when IGV Temp Control is selected OFF.... (Ya gotta love GE sometimes!)

It was explained to me many years ago that to reduce dynamic combustor pulsations during loading it was discovered that by using the IGVs to modulate air flow through the unit at that exhaust temperature the combustor and hot gas path parts would have a slightly longer life.

 

Can anybody tell me that why we put IGV temp control to off before we start online water wash at gas turbine GE MS9001e which is hooked up with hrsg?

 

During On-line WW, IGV's should be fully opened to make it a better cleaning. So it is a must to keep the unit on Base load.If you just keep the IGV temperature control on rather than keeping the FSR on temp control, it can close the IGV to attain the IGV reference curve for unit efficiency optimization by increasing the firing temperature (Usually called as IGV temp control Curve)

hope this will help..