Effect of Fuel Gas Temperature for Gas Turbine


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We are operating a GE Frame 5 machine on 100% Gas fuel at around 65 degree C. Will it be more economical/energy efficient to raise the temperature of Gas to a higher temperature say 80 deg C? We have ample scope for the same in our gas heater. Will the Gas turbine fuel nozzles be affected at higher temperature of gas fuel? Can you cite example where higher temperature of gas fuel is currently is use?

For information - we are using RLNG as gas fuel. Current flow is around 150 T/D for 22.5 MW machine.
There is a school of thought (backed up by data) that says that higher fuel gas temperatures result in a better overall heat rate (cold gas fuel being injected into the combustors through the fuel nozzles cools the combustion gases and requires heat to warm up the fuel and maintain combustion temperatures). I think it all really depends on what is used to heat the fuel--some "waste heat" medium (condensate; etc.) or if the heat source has to be created using electricity or gas or propane/butane/etc. And, further, it's a fractional percentage increase in heat rate--which for a 22.5 MW unit would be negligible, but for a 280 MW unit would be detectable and over a very long period of time (years) would certainly be worthwhile, again, depending on the source of heat to raise the fuel gas temperature.

Finally, yes, one would also have to consider the fuel nozzles and fuel delivery system (control valves and piping) when deciding how much to increase the gas fuel temperature.

You really should work with a knowledgable engineering firm or the turbine OEM or approved packager to understand all the ramifications--good and bad. It would likely be necessary--and prudent--to insulate the fuel gas piping in the compartment where the control valves are located. And, some of the components in the compartment may not be rated for the higher compartment temperatures which will result from a higher gas fuel temperature.

Hope this helps!!