We are facing the problem of load limitation of our one of GT. It is following the FSR curve in place of CPD curve as compare to our other GT in similar working conditions. Control constant given below.

<b>[Moderator's note: could not figure out how to fix this table for display on screen, sorry]</b>
<pre>
Description Value GT1 value GT2 value
TTK0_C  Exhaust Temp Control Curve #1 CPD Ref Corner,CPD B    psi <+87.3125 psi> SEQ_TRB2 54 6.02 5.56
TTK0_I   Exhaust Temp Control Curve #1 TX Ref Isothermal     deg F<+1040. deg F> SEQ_TRB2 54 560 560
TTK0_K  Exhaust Temp Control Curve #1 TX Base Slope,DW BIA       % <+48.0352 %> SEQ_TRB2 54 48.04 45.62
TTK0_LG Exh Temp Control Ref Slope, DW Bias        F/MW<+7.1304 F/MW>SEQ_TRB2 54 3.961 3.961
TTK0_LO Exh Temp Control Ref Corner, DW Bias                MW <+12.4844 MW> SEQ_TRB2 54 12.5 12.5
TTK0_M    Exhaust Temp Control Curve #1 TX Ref Slope                F/%<+4.8042 F/%> SEQ_TRB2 54 2.67 2.23
TTK0_S   Exhaust Temp Control Curve #1 CPD Ref Slope       F/psi   <+2.43213 F/psi SEQ_TRB2 54 19.6 17.99
TTK1_C   Exhaust Temp Control Curve #2 CPD Ref Corner,CPD B         psi <+89.625 psi>SEQ_TRB2 54 6.18 6.55
TTK1_I    Exhaust Temp Control Curve #2 TX Ref Isothermal            deg F<+1080.125 deg  SEQ_TRB2 54 582 582
TTK1_K  Exhaust Temp Control Curve #2 TX Base Slope,DW BIA      %<+58.94 %>SEQ_TRB2 54 58.94 57.44
TTK1_LG  Exh Temp Control Ref Slope, DW Bias       F/MW<+0.00 F/MW> SEQ_TRB2 54 0 0
TTK1_LO Exh Temp Control Ref Corner, DW Bias                         MW<+35.6 MW> SEQ_TRB2 54 35.6 35.6
TTK1_M   Exhaust Temp Control Curve #2 TX Ref Slope                F/% <+6.178223 F/%> SEQ_TRB2 54 3.43 2.11
TTK1_S   Exhaust Temp Control Curve #2 CPD Ref Slope            F/psi<+2.415 F/psi>SEQ_TRB2 54 19.46 17.87
TTK2_C   Exhaust Temp Control Curve #3 CPD Ref Corner,CPD B       psi <+87.625 psi> SEQ_TRB2 54 6.04 5.56
TTK2_I    Exhaust Temp Control Curve #3 TX Ref Isothermal         deg F<+1040. deg F> SEQ_TRB2 54 560 560
TTK2_K   Exhaust Temp Control Curve #3 TX Base Slope,DW BIA         %<+48.0352 %> SEQ_TRB2 54 48.04 49.38
TTK2_LG  Exh Temp Control Ref Slope, DW Bias            F/MW<+7.1304 F/MW> SEQ_TRB2 54 3.961 3.961
TTK2_LO  Exh Temp Control Ref Corner, DW Bias                  MW <+12.4844 MW> SEQ_TRB2 54 12.5 12.5
TTK2_M   Exhaust Temp Control Curve #3 TX Ref Slope           F/% <+4.8042 F/%>SEQ_TRB2 54 2.67 0
TTK2_S   Exhaust Temp Control Curve #3 CPD Ref Slope             F/psi<+2.233 F/psi>SEQ_TRB2 54 17.99 17.99
TTK3_C   Exhaust Temp Control Curve #4 CPD Ref Corner, CPD B          psi <+0.0 psi>SEQ_TRB2 54 0 0
TTK3_I    Exhaust Temp Control Curve #4 TX Ref Isothermal              deg F<+0. deg F>SEQ_TRB2 54 -18 -18
TTK3_K    Exhaust Temp Control Curve #4 TX Base Slope, DW BIA       %<+0.00 %> SEQ_TRB2 54 0 0
TTK3_LG  Exh Temp Control Ref Slope, DW Bias                 F/MW<+0.00 F/MW>SEQ_TRB2 54 0 0
TTK3_LO   Exh Temp Control Ref Corner, DW Bias               MW <+0.0 MW> SEQ_TRB2 54 0 0
TTK3_M     Exhaust Temp Control Curve #4 TX Ref Slope              F/% <+0.00 F/%> SEQ_TRB2 54 0 0
TTK3_S      Exhaust Temp Control Curve #4 CPD Ref Slope                      F/psi<+0.000 F/psi>SEQ_TRB2 54 0 0</pre>

 

<b>WHEN DID THIS PROBLEM START?</b>

After a maintenance outage?

<b>What Process- and Diagnostic Alarms are annunciated when this condition is occurring?</b>

Is this a single-shaft Frame 5 (MS-5001) or a two-shaft Frame 5 (MS-5002)?

Conventional combustors or DLN-I combustors?

The primary exhaust temperature control bias is usually signal name TTRXP, making the secondary exhaust temperature control bias TTRXS. Under normal circumstances (that is, when the CPD transmitter is calibrated properly, properly valved in, the Speedtronic input is working properly and scaled properly, the MW transducer is calibrated and working properly, and the Speedtronic input for the MW transducer is working properly and scaled properly) then TTRX will be the lower of TTRXP or TTRXS (should be TTRXP under normal circumstances).

If the unit is a two-shaft machine, then there may be some bias applied to TTRX; see the CSP or application code for your machine. But, I believe it would be applied to either TTRXP or TTRXS, so it shouldn't make any difference to your problem.

You can work through the CSP or application code and use the Control Specification to calculate and plot your own exhaust temperature control curves using the Control Constants below. We don't have enough information to be able to do that for you.

 

> We are facing the problem of load limitation of our one of GT. It is
> following the FSR curve in place of CPD curve as compare to our other GT in
> similar working conditions. Control constant given below.

---- snip ----

One simple question. Is your intake air temperature or compressor inlet temperature for the GT of interest is similar to the other GTs? If the answer is "YES", I'm afraid that I have nothing to contribute. If the answer is NO, let's talk about it.