Tripping of Gas Turbine Generator (GTG) on Failure of Extraction Fan
Tripping of Gas Turbine Generator (GTG) on Failure of Extraction Fan
(OP)
Hi,
We had discussion this morning on GTG protection. Is it common to trip a gas turbine due to failure of extraction fans?
Fyi, the GTG is located inside an ecoustic enclosure. There are 2 X 100% extraction fan (1 ruuning + 1 standby). I was told that if both the extraction fans are not working, this will triger the trip funtion of the GTG.
Just wonder, the sophisticated & very expensive GTG is dependent on these 2 small extraction fans? Makes sense?
Any experiences to share?
Thanks
norzul
We had discussion this morning on GTG protection. Is it common to trip a gas turbine due to failure of extraction fans?
Fyi, the GTG is located inside an ecoustic enclosure. There are 2 X 100% extraction fan (1 ruuning + 1 standby). I was told that if both the extraction fans are not working, this will triger the trip funtion of the GTG.
Just wonder, the sophisticated & very expensive GTG is dependent on these 2 small extraction fans? Makes sense?
Any experiences to share?
Thanks
norzul





RE: Tripping of Gas Turbine Generator (GTG) on Failure of Extraction Fan
What do the extraction fans do? Assuming they ventilate the enclosure of the GTG; if they fail then the temperature in the enclosure would rise rapidly. Dpeending on what else is in the enclosure (equipment, people, etc) this could be significant.
I suggest that you confirm that this is the case and try to find the logic behind it
Regards
Dave
RE: Tripping of Gas Turbine Generator (GTG) on Failure of Extraction Fan
By ensuring a continuous change of air in side the enclosure, small gas leaks do not become large pockets of potential explosion – larger gas leaks get picked up by gas detectors.
The continuous air flow helps to keep the enclosure temperature down. This will help ancillary pieces of equipment to survive longer (e.g. flame detectors, dampers)
You should have enclosure temperature detectors fitted to your installation. By lowering the enclosure temperature, the temperature sensors can pick up a significant change in enclosure temperature (possible leaks from cooling air supplied to PT or exhaust gas) at an earlier stage.
RE: Tripping of Gas Turbine Generator (GTG) on Failure of Extraction Fan
I guess in order for the explosion to happen, we need to have more than triple jeorpardy cases:
1) 1 normal running extraction fan fails
2) 1 standby extration fan also fails
3) The natural gas leaks
4) Temperature above auto ignition or there's ignition source
5) Alarm doesn't trigger
I don't know how fast the temp rise if both the extraction fails. In our case, the GTG is designed to be unmanned i.e. not normal for the people to be inside the enclosure.
Anyway based on your experience, is this kind of arrangement normal?
RE: Tripping of Gas Turbine Generator (GTG) on Failure of Extraction Fan
rmw
RE: Tripping of Gas Turbine Generator (GTG) on Failure of Extraction Fan
RE: Tripping of Gas Turbine Generator (GTG) on Failure of Extraction Fan
John
RE: Tripping of Gas Turbine Generator (GTG) on Failure of Extraction Fan
A lot of people believe that as long as you exclude any one of these three (e.g. the source of ignition) then safety is assured. However, in the UK, it is generally accepted that if you have present both fuel AND oxygen, then God will provide a source of ignition!
Brian
RE: Tripping of Gas Turbine Generator (GTG) on Failure of Extraction Fan
the trip function associated with the fans depends on what are you protecting.
some compartments are pressurized above ambient pressure, some are maintained below ambient pressure... what kind of fuel are you using?
if the fuel is toxic (like syn gas) then surely the oem added a trip in case the ventilation system fails.
if the concern is temperature rise, then the failure of the 2nd fan should alert the operator and a normal shutdown initiated when the compartment temperature reaches the alarm level.
if the concern is the presence of hazardous gases then the haz gas detectors should detect the condition and initiate the appropriate protection actions, e.g. a trip.
HTH
saludos.
a.