2015, ITS TMOS SCADA

Recently I was summoned to a site on a field troubleshooting assistance request from a customer, who reported that his GE Frame 9EA (PG9171EA) gas turbine gets high exhaust temperature spread alarm when it is on temperature control (simple cycle operation).

I made use of one of the very versatile tools in ITS Turbine Monitoring System HMI TMOS SCADA, the Dynamic Flame Swirl chart to help troubleshoot the root cause of the problem. In within 3 hours of monitoring using the said tool and analysis thereafter, I managed to pinpoint the root cause, which was later verified by the customer. It saved the customer from possible gas turbine tripping and having to execute a complete Combustion Inspection (CI). 

Conclusion

By correlating the characteristics of exhaust flame swirl angles at each load set-points with the corresponding exhaust temperatures profiles, and with consideration of known measurement error, ITS is able to conclude that there are clogs in fuel nozzles 8,9 or 10 that reduce gas flow, producing leaner combustion, cooler exhaust temperature and higher exhaust temperature spread.

It is strongly advisable to dismantle the said nozzles for inspection and replacement. Continuous operation in high exhaust spread condition will shorten the life cycle of turbine buckets as they were exposed to rapid heating-cooling cycles.

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