I would like to see if the GT is underfiring. I guess with the TTK_C constants I can draw the theoretical curve and with PI data I can draw the real curve with TTRF1 and see where the unit is running, am I right?
Any feedback appreciated.
This is a MkVI unit.
Does anyone have a TTRF calculator spreadsheet?

 

GE-design heavy duty gas turbine exhaust temperature and the combustion reference temperature cannot be equated.

TTRF, or TTRF1, are <b>reference</b> temperatures; they are approximations of flame temperature and not actual firing temperature, which is the temperature of the combustion gases exiting the first stage turbine nozzles. Combustion reference temperature is used solely for determining when to change combustion modes.

The algorithms for calculating TTRF, orTTRF1, are proprietary as far as I know. I've seen some people try to build a formula for calculating combustion reference temperature by reverse engineering the algorithm using empirical data, but they don't generally prove to be very accurate over all ambient conditions.

I was at a test site where some T/C rakes were temporarily inserted into the hot gas path in an effort to test the accuracy of the TTRF1 calculation. It was within 2 deg C of the actual firing temperature over the ambient conditions being experienced during the two days of testing (which was only about 8 deg C variation at that time of year).

The two most common problems with under- or over-firing are CPD pressure transmitter calibration accuracy and IGV LVDT calibration, with the latter being the most common issue. These two issues are followed closely by axial compressor cleanliness and condition and exhaust duct back pressure issues.

The formula for calculating CPD-biased exhaust temperature reference, TTRXP (for Primary, or CPD-biased, exhaust temperature reference) has been posted many times on control.com. You need all of the Control Constant values, not just the "corner" values.