GE94-02: Repair Flow Testing and Calibration Procedures for ...

The use of primary fuel split modulation is the main tool for tuning emissions problems. The
effect of primary split on NOx and CO emissions is discussed, and specific procedures are given
on how to adjust control constants in order to change split. The impact of combustion
dynamics in emissions tuning is discussed.
When emissions cannot be corrected though the use of fuel split alone, additional options are
presented for trying to correct the problem. Separate approaches to solving emissions
problems are presented for base load and part load premixed operation. Lastly, the problem of
the failure to transfer into premixed mode is discussed, and techniques for correcting the
problem are presented.
GE24‐13D2.6: Tuning Procedure for General Electric DLN‐2.6 Combustion
Systems. June 2005.
This document presents procedures for performing combustion tuning on DLN‐2.6 combustion
systems. These combustion systems are found on GE 7FA, 7FA+ and 7FA+e combustion
systems.
The common reasons for tuning a DLN‐2.6 combustion system are
1. To follow OEM guidelines recommending that tuning be performed after any
combustion system hardware is replaced
2. To monitor and minimize combustion dynamics as they change in response to seasonal
ambient temperature variations
3. To troubleshoot emissions or dynamics excursions outside permitted levels during
normal unit operation
The first two items deal with tuning when there may not be any specific problem with the unit.
They involve tuning to ensure that the combustion operation is optimized, that is, operating
with sufficient NOx and CO margin while at the same time minimizing combustion dynamics.
The third item involves tuning to troubleshoot a combustion‐related problem. Typically, in a
troubleshooting situation, a review of historical turbine and emissions data is first
recommended before commencing with tuning. In all cases, tuning is primarily carried out
through the modulation of either two or three fuel split schedules which control the spatial
distribution of fuel within the combustion system.
This document starts with an overview of the DLN‐2.6 combustion system and dynamic trends
that are characteristic of the DLN‐2.6. Then specific tuning guidelines are presented discussing