Hello everyone.

I am working with GE frame 6 machine (34 MW capacity, uprate done recently) driven by Mark VIe control system.

GT uprate and control system (Mark IV to Mark VIe) up gradation done recently in Oct-11.

GT load observed up to 34 MW max at base load.
As part of uprate scheme CPD slope, corner and FSR slope, corner value were changed to maximize opening of IGV (i.e. 86').

Today we made IGV on, when GT was on part load (28 MW), after 6 hours.
when need came for load increase, it was observed that the GT was on base load (FSRT minimum) at 25 MW, with IGV opening around 56'!!!!!

Why this so??
Is it normal phenomena or something wrong.
As i understand, at part load IGV should be less open but there should be margin for load increase.

Is it possible to turbine reach at base load (FSRT minimum) at 25 MW, if IGV temperature control mode is ON.

Kindly reply, as i need to answer this urgent.

 

> Is it possible to turbine reach at base load (FSRT minimum) at 25 MW, if IGV
> temperature control mode is ON.

> Kindly reply, as i need to answer this urgent.

At true base load condition the IGV's need to be full open (86 degrees in your case), even if you have IGV temperature control for combined cycle (heat recovery) operation. So something is wrong if you are indicating base load at 25 MW and IGV's at 56 degrees. You may well hit the base load exhaust temperature limit at 25 MW if the IGV's fail to open.

You should verify that no one has put the IGV control into manual mode, which would keep them from opening unless the operator manually opened them using the IGV manual control on the HMI.

 

Sir,

we have checked the all possibilities, we observed that control constant TTKVGI (IGV temp control isothermal limit) is not matching with the previous control constant.

Earlier it was 1045'F(Mark IV) and now it is 1080'F (Mark VI).

I have checked the algorithm, but not fully clear to me.
Does it may cause the problem??