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We are running a Frame-6 Mark-V gas turbine generator with HSD (diesel) as starting fuel and Naphtha above 5 MW. At 5 MW we get the permissive to change fuel from HSD to Naphtha.

I would like to know if this fuel change over set point could be reduced to 3 MW and its probable consequences.

Dear All,

Fuel changeover from the Diesel/Gas to naphtha requires basically two things.

1.As the naphtha is highly viscous fluid it requires sufficient temperature in the combustion chamber to establish a stable flame.

2.At low flows naphtha distribution will not be uniform to all fuel nozzles.

Considering the above two reasons the fuel changeover permissive from diesel to naphtha is given at 5MW. Even it is always better to perform fuel change at higher loads. SO it is not advisable to change the set point from 5MW to 3 MW.

*** But if the flow divider is provided then the flow distribution problem will not be there***

My doubt is whether your machine is having a flow divider? I know few machines provided with the flow divider are able to start the gas turbine on Naphtha itself.

Hope i clarified Ur doubt.

waiting for Ur reply.

Why didn't you ask why you can't start and stop the machine with Naptha? Or why you can't switch to Naptha at 50% speed, or 95% speed? Or as Full Speed-No Load?

There may be any number of reasons why. One may be that the fuel nozzles can't properly atomize the Naptha at flow-rates below those experienced at 5 MW. Or the control valve isn't stable when operating with Naptha at flow-rates below 5MW.

This question is best asked of the packager of your Frame 6 Mark V heavy duty gas turbine. Because only they can tell you precisely why that value was chosen.

Or, if you own the machine (meaning it's not under warranty of any kind) and you want to try transferring fuels at some other value, have at it! Just be prepared to accept the consequences of changing the setpoint.

The probable consequences include smoking, incomplete combustion, liner collapse, fuel nozzle damage, transition piece damage, loss of flame, high exhaust temperature spreads.

thanks for sharing the information. Both of you have cleared my doubts to a large extent.

thanks Anil and CSA for the information. This will really be of great help.