Energy & Utilities | Turbines

A new Approach to Turbine Combustor Flame Sensors

25 Sep 2017, by Laurien Maerman

Leading up to the 18th annual Australian Gas Turbines Conference on the 29-30th of November, we reached out to John Devine, General Manager at Fireye Inc. in the United States of America to gain a better insight into the current challenges and approaches to Turbine Combustor Flame Sensors.

 

There are significant application issues specific to turbines and their combustors, that present challenges in terms of flame detectors. John Devine states “To begin with, you have sighting locations that are high ambient temperature, high operating pressures and vibration with mechanical limitations that are all effectively working against you. In addition, the turbine typically has long duty cycles / operating times and potentially restricted access while operating. You therefore need devices not only with high safety integrity but also superior reliability. That by definition, requires detectors that are robust, self-checking, fail safe and designed to operate continuously.”

 

We then asked John to explain some of the current Flame Detection issues we are facing in the Gas Turbines Industry. John said, “Today, I come across many units still operating with older technology that is neither rated for continuous operation or fail safe applications. These older technologies are also typically high voltage devices that can create hazards in terms of maintenance. The move to lower turbine emissions can also potentially weaken the optical output from the flame, making detection generally more challenging.”

 

“Over and above these application type issues, there seems to be quite a variation in the types of agency certifications and area classifications needed. As a manufacturer, we need to design products that interface with existing and future turbine control systems in the precise way the OEM’s want these to work. Finally, other than the basic safety function, is there opportunity to do more flame analysis and provide more informational information about how well the flame is burning rather than just its presence or absence?”

 

With regard to overcoming these issues, John had some insightful suggestions. “The first step of course, is a clear understanding and definition of the issues. These may apply in a variety of ways or levels of severity depending on the different turbine OEM’s and the exact application. One of the more obvious steps is to try and remove the electronics part of the flame detector from the source of heat, vibration and pressure to give it a better life expectancy. We also need a device that is designed to be self-checking/ fail safe with a high mean time between failures – basically safe and reliable.”

 

“We can use low voltage, solid state sensing devices to eliminate the concerns on having high voltage present in the turbine enclosure. Flame detector manufacturers can build devices that interact with turbine OEM control systems, and can typically meet and obtain agency certification and area classifications. We do need to develop a clear picture of what the industry is demanding today and tomorrow.”

 

At the upcoming Conference, John Devine will be presenting “A New Approach to Turbine Combustor Flame Sensors” and will be discussing some field testing results. We asked John to give us an insight into some of the key results of this case study. “At the Conference we will be discussing two evaluations we have made to date. The first was conducted at the United Technologies Research Centre (UTRC) in Farmington, CT USA. The main objectives of the test were to demonstrate the gas turbine flame sensor performance in a realistic environment and representative fuel, temperature, pressure, injection etc. We also wanted to characterize the types of signal level, and signal fluctuations seen for a realistic turbine combustor application. The results basically verified we have good correlation between sensor signal and total fuel flow/ flame generation. The second test at Uniper in Rotterdam (ongoing) is an installed operational turbine. We are testing and evaluating the signals seen within the time and frequency domains from a more complex device that is connected to a software based, data acquisition system called Fireye Explorer (FEX). This is helpful because it allows us to have a graphic view of what the scanner sees on a continuous basis.”

 

John agrees that it is important to look into this new approach, “It makes sense to at least evaluate new approaches, especially as needs and technology change over time. If there is an opportunity to make potential improvement to safety, life expectancy and reliability with a modified approach why not take a look? Personally, I am interested in the way flame detectors have improved significantly over time and have become much more capable and powerful devices. With that capability and the ability to hook up software lies the power to see much more information and analysis from the flame that may be essential to developing more effective, efficient combustion going forward. That’s really true for traditional boiler based systems as well as gas turbines.”

 

The Conference is fast approaching on the 29-30th of November. What are you most looking forward to at the Conference?
“I’m particularly looking forward to learning more from the turbine experts and users that will be present at the conference and the show. Speaking honestly, I am not by any measure an expert on gas turbines. My expertise is in the application of optical flame detection and safety systems across a wide range of combustions systems. I think I can learn a lot from the many experts that will be there and we can interact with. I hope that will help us determine if we are on the right track or if we are missing any other possibilities. I certainly hope that the presentation and the questions and feedback we receive will help us develop a better product for the industry.”

The 18th Annual Australian Gas Turbines Conference returns to Melbourne in November 2017. The event forms Australia’s best known gas turbine industry meeting place; where operators, industry experts and technology providers share and exchange best practice in maintaining and operating gas turbines during this two-day conference and exhibition. Find out more and register today here.

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