Extended Premix Mode

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Thread Starter

mohamed nawar

for gas turbine 9fa DLN2.6E why when gas temp reach 17.5 c unit transfer to extended permix mode?
 
mohamed nawar,

>for gas turbine 9fa DLN2.6E why when gas temp reach 17.5 c
>unit transfer to extended permix mode?

That's an excellent question--for the OEM or packager of your turbine. I presume you are referring to when the gas fuel temperature drops to 17.5 deg C, not when it increases to 17.5 deg C., and my best guess would be that there's something about nearing the natural gas dewpoint temperature. The control system may be trying to avoid condensing liquids at low gas fuel temperatures. Liquids can be water--which would not be good to introduce into the combustor at high temperatures, or natural gas liquids--which can be very volatile and cause mini-explosions in the combustors.

Also, the OEM has has a lot of problems with flashbacks caused by long hydrocarbon chains which result from gas fuel temperatures at or near dewpoint temperatures. Flashbacks are not good for these machines, and can result in serious damage to the turbine nozzles and buckets.

But, for the precise answer for your site, I would suggest consulting the Control Specification, Sect. 05.02, provided with each Speedtronic Mark turbine control system for some possible information. AND, consulting the OEM or your long-term service provider (OEM; third-party supplier). You might also consult the comments (notes) in the sequencing or application code running in the Speedtronic turbine control system. Sometimes there are very good notes/comments about functions/features in the code running in the panel.

But, the best answer will come from the OEM/packager.

Hope this helps! Please write back to let us know what you find!
 
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mohamed nawar

thank you for your good analysis. this doesn't go in my head although. i will try to ask for code running and OEM and tell you
yes you are right when the gas fuel temperature drops to 17.5 deg C as at normal the set point temp for natural gas coming from water bath heater is 36 c.
 
Which power plant is it and where? I can help you out i think.

> for gas turbine 9fa DLN2.6E why when gas temp reach 17.5 c
> unit transfer to extended permix mode?
 
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