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GT air inlet temperature at compressor inlet is 2C more than the air temperature before inlet filter. This is happening when the ambient is going more than 45C. Is there any help from insulating the air intake structure?
Assuming the GT is running at or near rated speed, about the only way for the temperature to actually increase is via inlet air heating. If your machine does not have inlet air heating, I would suspect the accuracy of either or both temperature measurements, since there should be a drop in temperature due to the pressure drop.
If your machine does have inlet air heating, then either it is operating as per design, or the control valve is leaking.
If your machine does have inlet air heating, then either it is operating as per design, or the control valve is leaking.
There is something that we're not being told about this turbine and it's inlet configuration or you've a very special machine on your hands. Because, the Ideal Gas Law states that any time there is a pressure drop for a fluid that is flowing (and air is considered a fluid) that there will be a temperature drop as well. PV = nRT is the law, and you can look it up anywhere for a better explanation.
And there is usually a very significant pressure drop at the bellmouth of an axial compressor that is running at rated speed meaning that will most likely be a temperature drop at the bellmouth if measured as most compressor inlet temperatures are measured using thermocouples either immediately adjacent to the bellmouth or protruding through the bellmouth casting.
Now, if the wrong kind of thermocouple extension wire is used to connect the thermocouple to the Speedtronic turbine control system, or if the polarity of the terminations is not properly observed along the entire length of the circuit, or if the wrong type of thermocouple is used or configured in the Speedtronic turbine control panel then the Speedtronic has been known to show very little deviation between a thermocouple's reading at ambient conditions, and then a deviation will begin as the temperature being measured increases.
But, the most important question to ask is always: When did this problem begin? After a maintenance outage? After one or more of the compressor inlet (bellmouth) temperature thermocouples was replaced?
Another question to be answered is: A GE-design heavy duty gas turbine usually has at least two compressor inlet (bellmouth) thermocouples; do both thermocouples indicate the same temperature?
Yet another question to be answered is: Have you verified the polarity of all thermocouple and thermocouple extension wire connections between the thermocouples and the Speedtronic to be certain there is no problem?
Have you temporarily connected a spare thermocouple to the Speedtronic in place of one of the compressor inlet (bellmouth) thermocouples that seems to be deviating from expected and applied a known temperature to the thermocouple and observed the indication on the Speedtronic display?
There's a lot of information you haven't told us about this problem and what you have done to try to troubleshoot the problem. And, if the turbine has a unique inlet arrangement (other than a typical inlet filter, trash screen/silencer, elbow, reducer and transition) you haven't told us that either. It's highly difficult to imagine the kind of air flows that are experienced for GE-design heavy duty gas turbines being affected by ambient temperatures heating the air flow through the inlet duct. The flows are pretty high and, again, there is that pressure drop at the bellmouth (compressor inlet) that should also be causing a 1-2 degree F decrease from ambient temperature. Unless the inlet duct is painted with a very highly absorbent paint and the ductwork is exposed on all sides to direct sunlight at all times it's just difficult to imagine the inlet temperature being higher than the ambient temperature.
And, there's also the possibility that if the unit has DLN combustors and Inlet Bleed Heat that the IBH control valve is somehow leaking or opening when the ambient temperature is elevated (how would be another mystery) that IBH is heating the air, but, again, this is something you didn't (but should have) told us about the unit to get the most concise reply.
So, answer all the questions--even the ones you don't think are relevant and we'll do our best to try to help you. But, there's something amiss or something we don't know, and, certainly you haven't told us what you've done to try to troubleshoot the problem (which would have been very helpful).
And there is usually a very significant pressure drop at the bellmouth of an axial compressor that is running at rated speed meaning that will most likely be a temperature drop at the bellmouth if measured as most compressor inlet temperatures are measured using thermocouples either immediately adjacent to the bellmouth or protruding through the bellmouth casting.
Now, if the wrong kind of thermocouple extension wire is used to connect the thermocouple to the Speedtronic turbine control system, or if the polarity of the terminations is not properly observed along the entire length of the circuit, or if the wrong type of thermocouple is used or configured in the Speedtronic turbine control panel then the Speedtronic has been known to show very little deviation between a thermocouple's reading at ambient conditions, and then a deviation will begin as the temperature being measured increases.
But, the most important question to ask is always: When did this problem begin? After a maintenance outage? After one or more of the compressor inlet (bellmouth) temperature thermocouples was replaced?
Another question to be answered is: A GE-design heavy duty gas turbine usually has at least two compressor inlet (bellmouth) thermocouples; do both thermocouples indicate the same temperature?
Yet another question to be answered is: Have you verified the polarity of all thermocouple and thermocouple extension wire connections between the thermocouples and the Speedtronic to be certain there is no problem?
Have you temporarily connected a spare thermocouple to the Speedtronic in place of one of the compressor inlet (bellmouth) thermocouples that seems to be deviating from expected and applied a known temperature to the thermocouple and observed the indication on the Speedtronic display?
There's a lot of information you haven't told us about this problem and what you have done to try to troubleshoot the problem. And, if the turbine has a unique inlet arrangement (other than a typical inlet filter, trash screen/silencer, elbow, reducer and transition) you haven't told us that either. It's highly difficult to imagine the kind of air flows that are experienced for GE-design heavy duty gas turbines being affected by ambient temperatures heating the air flow through the inlet duct. The flows are pretty high and, again, there is that pressure drop at the bellmouth (compressor inlet) that should also be causing a 1-2 degree F decrease from ambient temperature. Unless the inlet duct is painted with a very highly absorbent paint and the ductwork is exposed on all sides to direct sunlight at all times it's just difficult to imagine the inlet temperature being higher than the ambient temperature.
And, there's also the possibility that if the unit has DLN combustors and Inlet Bleed Heat that the IBH control valve is somehow leaking or opening when the ambient temperature is elevated (how would be another mystery) that IBH is heating the air, but, again, this is something you didn't (but should have) told us about the unit to get the most concise reply.
So, answer all the questions--even the ones you don't think are relevant and we'll do our best to try to help you. But, there's something amiss or something we don't know, and, certainly you haven't told us what you've done to try to troubleshoot the problem (which would have been very helpful).
