factors affecting the base load

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Thread Starter

pv

what are the possible factors effecting the base load value of a GE 7 Fa gas turbine with Mark-VI machine?
 
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Bob Johnston

The main factor which is going to affect GT performance is Compressor Discharge Pressure, PCD or CPD. The major influences on CPD are:

1) Ambient temperature
2) Compressor cleanliness
3) Air Inlet Filter pressure drop.

Other items which will affect performance are ambient pressure & fuel specification.

Somewhere in your documentation you should have estimated performance curves which will allow to make some calculations to correct for deviations from ISO conditions and estimate what your performance should be on any given day.
 
Yes, these are the major factors for most gas turbines, but GE now uses CPR (Compressor Pressure Ratio) as the bias for exhaust temperature control for nearly every F-class unit, and many B/E class units now, also. CPR is a "fancy" CPD (Compressor Pressure - Discharge) value, which is calculated using Ambient Pressure transducers, three redundant 96AP transducers. The calibration and operation of these transducers can greatly impact the output of the gas turbine-generator.

Exhaust duct back pressure can also negatively impact power output, though in this author's experience the impact is usually only 0.5-1.0%, or so of rated output. It is believed that some combined cycle control schemes also factor exhaust duct back-pressure into the control.

There have also been documented cases of compressor bleed valves leaking which have reduced power output.

F-class turbines use inlet bleed heat and the inlet bleed heat control valves are fail-open (normally open) valves and have been known to leak at Base Load, which can reduce power output, also.

These F-class units are very "sensitive" machines, and require a much higher amount of TLC (Tender Loving Care) than most previous heavy-duty gas turbines. Of course, they also have a higher power output, too.

markvguy
 
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