Automated combustion tuning on the cusp of mainstream

You can put a point on the electric power industry’s technology timeline at 2011 for commercial acceptance by owner/operators of automated gas-turbine combustor tuning systems. That was the conclusion of the editors based on presentations (user and vendor) and discussions at the 7F Users Group meeting, which concludes today in Houston.

The dry low-NOx (DLN) combustion systems that helped gas turbines become the preferred generation alternative made users aware of “combustion dynamics.” Recall that DLN combustion systems are prone to flame instability under certain operating conditions and the resulting pressure pulsations (dynamics) can be strong enough to damage both combustors and downstream hot-gas-path components. Access CCJ article Monitoring—and mitigating—combustion dynamics.

To mitigate the destructive effects of these pulsations, OEMs participated in the development of combustion dynamics monitoring systems. The CDMS warns operators of impending instability, enabling them to make the necessary adjustments to maintain stable combustion.

The early CDMSs, which debuted only a few years ago, were “manual” systems. The ratcheting downward of emissions limits and plant staffs help put the development of automated systems on the fast track.

A user presentation on Tuesday updated the group on the status of tuning systems, which have automated the functions of the CDMS and integrated them into a controls package that assures optimal operation of the gas turbine on a continuous basis.

The user-presenter, who is the control system troubleshooter for a major F-class fleet, said he thought the following three tuning systems acceptable for powerplant use:

* PSM’s AutoTune system.

* Gas Turbine Efficiency’s ECOMAXTM.

* The OEM’s OpFlexTM.

The controls expert said AutoTune was installed on three GE engines in his fleet, ECOMAX on two. OpFlex was not considered for deployment because of its cost, he noted.

Most of the speaker’s experience was with AutoTune, which has accumulated more than 8000 hours of operation integrated with Mark V and Mark VI control systems. Performance has been validated in all seasons and at ambient temperatures from 20F to 100F. Feedback from the plants has been good, he said.

Benefits of the system, he continued, were these:

* Eliminates the need for seasonal manual tuning.

* Reduces the risk of lean blowout events.

* Improves emissions control throughout the year.

* Minimizes combustion dynamics, thereby maximizing hardware life.

* Accommodates changes in gas properties while maintaining top performance.

* Expectations are the same basic system will be suitable for Siemens gas turbines as well as GE’s. Development work on AutoTune for the 501F is underway.

The PSM system, he continued, is customizable to meet the specific needs of each site. It is manufactured using industrial grade electronics, not Windows. Plus, it has an easy-to-use operator interface that is much like the Mark V screen.

Vendor presentations

PSM was one of the nine companies presenting to the 7F owner/operators Wednesday afternoon. Tim te.Riele, VP Engineering/R&D, focused on compressor upgrades, sharing with the users what PSM identified as the OEM’s field issues and how it redesigned critical components to eliminate problems currently experienced. He covered the R0 upgrade and the S0-S4, S13-S16, and S17/exit guide vane packages. The highlights of what te.Riele said were included in the company’s sponsored statement posted Tuesday.

 

Gas Turbine Efficiency was another Wednesday afternoon vendor presenter. Chris Chandler, VP Turbine Optimization, told attendees that ECOMAX is installed on 16 7FAs equipped with DLN-2.6 combustion systems and has more than 71,000 operating hours. Two additional systems currently are being installed. In sum, six plants have integrated the GTE system and Mark V and Mark VI controls.

ECOMAX is an executable program that can reside on any PC, Chandler said, and it can communicate directly with the GT controller, Cimplicity, and the DCS. Plus, all control can be through the DCS. He ran through a list of system benefits that closely paralleled those above for PSM. In addition, ECOMAX can resume automated tuning after a combustion inspection or hot-gas-path inspection without any onsite or remote assistance.

For details on how ECOMAX works, access the linked CCJ article developed from material presented to the 7F Users Group in 2009 by a team of engineers from Entegra Power Group who “kicked the tires” for nearly a year before talking to he group.

Contact Megan Thomas, Director of Marketing and Communications, for more information.

 

Dresser-Rand Leading Edge Turbine Technology Services reviewed its latest technical solutions for F-class component repair and refurbishment. Director of Engineering Greg Snyder presented the details. He focused on the rotor—its maintenance, life assessment, and life management.

Click on the short video and allow Snyder to tell you about the company’s new rotor shop. For details on the company’s 7F repair capabilities, click here.

Tetra Engineering Group Inc’s Frank Berte spoke to performance analysis of heat-recovery steam generators, offering his expertise on the impacts to the HRSG of low-load GT operation. The boiler expert had a similar presentation at the 501F and 501G Users Groups meeting earlier in the year. If you missed it, click here.

 

Mee Industries Inc. There haven’t been any significant changes to the company’s successful approach to fogging since Thomas Mee presented before this organization a couple of years ago. However, the marketplace is more receptive to fogging today than it has been in the recent past given design improvements to R0 compressor blades. In brief, these airfoils are now able to tolerate water from a well-designed fogging system—at least PSM’s R0 blades can.

Mee said that his company has supplied fogging systems for 70 7FA turbines since 1997 and that two GE foggers are now being replaced with MeeFog systems. Also, he mentioned that several plants are in the process of reactivating fogging systems laid up when the R0 cracking epidemic surfaced. For background information on the design of fogging system, access To fog or not to fog: What is the answer?

Posted in 7F Users Group |

One response to “Automated combustion tuning on the cusp of mainstream”

  1. Ray Martens says:

    How do the auto-tuning systems measure inlet air flow? Are any of the auto-tuning systems being used on engines that are in AGC control and how well do they respond to load swings of ~ 10 MW / minute per engine?

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