Hi

As U know it's impossible to measure the inlet hot gas temperature to the various stages of the turbine. So wheel space thermocouple positions is in fact in back of the buckets near the bucket root.

So my question is what's really is this temperature regarding there is cooling air flow in this area. I checked first and second and third stage temperatures in a F9 and can't find a logical relation between these temperatures. For example stage one's aftward temperature is 100 degree more than it's forward! (TTWS1AO1=474 & TTWS1FO1&TTWS1FI1=375).

Another question: how much is approximately firing temperature in a typical F9 or F6 or F5??And is that calculable?

 

dontknowman,

The subject of wheelspace thermocouples has been covered many times before on control.com, and past threads can be viewed using the 'Search' feature of control.com.

GE defines firing temperature as the temperature of the hot gases entering or exiting the first stage turbine nozzles (depending on whether the first stage turbine nozzles are air-cooled or not). It is calculated by the control system of all DLN combustor-equipped GE-design heavy duty gas turbines; the signal name is TTRF or TTRF1. It is approximately 2000 deg F for non-F-class machines (and non-HA-class machines) and is as much as 200 deg F or more higher for F- and HA-class machines. The purpose of calculating firing temperature for DLN combustor-equipped units is to use as the switching point for combustion modes.

CPD- or CPR-biased exhaust temperature control approximates a firing temperature limit using CPD or CPR in combination with exhaust temperature.

But actual firing temperature is not measured or used for feedback in control schemes.

Hope this helps!!!

 

Thank you dear CSA