Turbine Topics Archives - Turbine Logic

Tending to Your Engine Warning Light

I like to slow down and leave the beaten path when I’m not working feverishly to solve gas turbine and energy related problems. Leaving the beaten path often involves a retreat to my cabin in the north Georgia mountains. My gateway to the cabin and the many nearby forest service roads is my old F-150 pickup truck that I’ve had for the duration of my career. Despite its resilience through the many challenges I’ve thrown at it, the truck does have its breakdowns.

When I hear stories of forced outages at plants, I am often reminded of my experiences getting stuck in the mountain forests of north Georgia. These breakdowns inevitably arise deep in the woods with an approaching storm or nightfall when reliability is needed most. Usually the breakdown occurs because of a small issue that finally grew too big. For example, a sensor has drifted too far out of spec or a vacuum hose may fail after months of developing small cracks and vacuum leaks.

Thankfully, modern vehicles have all sorts of warning lights to alert you to any potential issues with sufficient time to get repairs. In a similar way, combustion dynamics monitoring systems provide the same service to gas turbine operators. By capturing and trending the signature of a gas turbine combustion system, CDMS is the warning light before a critical failure occurs in a gas turbine hot section.

Watching the Check Engine Light

If my truck had modern on-board diagnostics, it would surely have saved me many wet or dark hikes out of the woods. I don’t have these issues in the city when I am commuting or driving with my family. The modern-day vehicles that I use for these purposes have advanced on-board diagnostics that can detect an instrumentation fault or even the smallest vacuum leak long before it causes drivability issues. When the “check engine” light comes on, I have plenty of time to plan for repair. Thanks to advanced on-board diagnostics, the surprises that happen in the woods with my old truck just don’t happen with these modern cars, even though the truck is a simpler and more rugged machine.

Operating a gas turbine without these advanced monitoring systems is just like driving an old truck through the forest. As long as things are running, the day continues as planned until the unexpected inevitably changes those plans. Meeting all of the maintenance intervals does not change this fact. Operating a gas turbine with an advanced CDMS algorithm is like the modern vehicle with on-board diagnostics. Surprise breakdowns are very un-common; when they occur, there is almost always a warning or precursor that has been available and not acted on by the user.

On-board Diagnostics for Gas Turbines

Similarly, a combustion dynamics monitoring system can save a gas turbine plant from forced outages. Advanced CDMS trending algorithms can identify small changes in combustion dynamics trends. These algorithms can distinguish between underlying hardware faults, instrumentation faults, and tuning issues. Operators who use this software receive advanced warning of impending failures with sufficient time to plan an inspection or outage. Just like your car’s dashboard, CDMS systems provide several warning lights providing a glimpse into the health of your gas turbine.

While the CDMS system helps identify and thus protect against damaging levels of combustion dynamics, it can offer much more when coupled with advanced trending software. This is because small hardware faults, such as hot section cracks, can have significant impact on combustion dynamics characteristics. A small developing crack in a combustor liner can make the combustor louder, or quieter, or perhaps shift the frequency of a tone. A hardware fault does not always manifest as a loud combustor!

Getting Up to Speed

I find it interesting that gas turbines lag in this technology despite their cost and availability of repair. Part of this is related to the size of the user base. For example, almost one million F-150s were sold each year during the last three years. Thanks to the vast user base, every conceivable issue has been discovered by someone and posted on the internet with a fix. Nearly any issue can be fixed at home, or in the woods, with some DIY effort and minimal value at risk.

Nevertheless, we have a world were automobiles have state of the art monitoring diagnostics despite cheap and easy availability of service, while gas turbines have limited advanced monitoring despite the high cost and low availability of service. At the center of this conundrum is the smaller user base and slower adoption of artificial intelligence by the gas turbine industry. By employing advanced CDMS and advanced trending software, we begin to embark down the path of the modern vehicle.

CDMS is the Warning Light You’ve Been Waiting For

The message that I hope to instill with this newsletter is the opportunity to embrace advanced monitoring algorithms for combustion dynamics. Combustion dynamics offer a rich data stream that can hold clues about the health of many components on the engine. Other industries have embraced similar technology, and consequently we can enjoy things like highly reliable vehicles. Third-party addition of such technology to an existing gas turbine is typically relatively easy, and can bring the modern day expectation of reliability to an older asset.

As for my time in the woods, I will forge ahead with the old truck which has the right combination of character and value to smash through old mountain culverts and graze the occasional tree. When things break down, a little YouTube engineering usually gets me out of the woods, and my worst-case scenario is a hike in the woods. Does this measure up to your worst-case scenario in a gas turbine forced outage? If not, I encourage you to explore combustion dynamics monitoring and the potential that it offers with advanced dynamics trending algorithms.

Yours truly, Tim Lieuwen, CTO – Turbine Logic

Executive Director – The Strategic Energy Institute at Georgia Tech

Photo by Justus Menke on Unsplash

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Geothermal Energy: The Power Source Hidden Underneath

It took a million-dollar Netflix production and a teenage superstar for many of us to realize that geothermal power is as widespread in northern countries as gas turbines are in the rest of the world. Zac Efron’s Down to Earth highlights how geothermal energy in Iceland could in fact be the key to the future of energy production.

Geothermal energy (Geo – Earth, Thermal – Heat) is a resource captured from the reservoirs of hot lava that exist at great depths below sea level on Earth. Large drills are used to access these reservoirs, and steam or hot water is brought back up to the surface to use in various applications – heating and cooling of buildings, electricity generation.

Due to the reservoir’s natural heat regeneration rate, geothermal energy is categorized as a renewable resource. There is extraordinarily little of the Earth’s deep crust we use for power generation, and therefore this resource is expected to help us last for the next foreseeable future. The benefits of geothermal energy continue, as it can be captured irrespective of the time of day or weather conditions, and less byproducts are seen in the capture of energy. For example, geothermal energy produces virtually no greenhouse gases¹, consumes less water on average compared to other energy capture resources, and less land is required to set up a geothermal power plant compared to a coal plant or solar photovoltaic plant², meaning less of the existing environment needs to be demolished or changes in order to incorporate a power plant.

Iceland is a geothermal hotspot on Earth. Sitting across continuously shifting tectonic plates and volcanic activity, Iceland has the unique geographical features that promote the deep drilling of the Earth’s core. The north tip of the Eurasian and North American tectonic plates sit on the coast of Rekjanesbaer, approximately 50km (31 miles) west of the Icelandic capital of Reykjavik. Tapping into the gaps between these plates, some nearly 50 feet wide, enable us to access hotspots miles below the bottom of the ocean. The Iceland Deep Drilling Project (IDDP) incorporates a group of scientists that establish drilling locations at these hotspots around the country; they drill to depths of 5km (3 miles) and look for temperatures of 600^oC (1112^oF)³ in order to efficiently capture this energy source, and ideally would want to dig even deeper in order to harness energy at even hotter temperatures⁴.

This seems too good to be true. Is there a catch?

Geothermal Energy is best captured where hot lava reservoirs can be accessed. This essentially limits the locations around the world where this is possible. Although ideally this could be done on any piece of land situated along a shifting tectonic plate, sustaining these locations becomes a challenge as access to these hotspots can be quite limited, especially if they are out in the middle of the ocean. In the United States, we see that most of the west sits on top of hotter land than the east⁵. Therefore, geothermal capture, say in and around Yellowstone National Park, would prove to be extremely beneficial. Nevertheless, the energy that can be captured by one or two geothermal power plants is not on the same order of magnitude of the power that can be captured by a gas turbine of the same size, it is expected that geothermal energy will prove to be an extremely important alternative to burning coal for heat purposes.

At the moment, California produces the most geothermal energy in the United States⁵. The hot geysers in Northern California have provided dry steam for the world since as early as 1960. While Iceland’s geothermal plants have been pursued since the early 2000’s we now see that the energy capture has been streamlined and is starting to provide for various needs of the country.

In fact, it seems to be so streamlined, even Zac Efron decided to pay a visit.

References:
1 Argonne National Lab. Life Cycle Analysis Results of Geothermal Systems in Comparison to Other Power Systems; Figure 16, page 43. August 2010.
² Geothermal Energy Administration. A Guide to Geothermal and the Environment. 2007.
³ Report of workshop no. 2 of the iceland deep drilling project, nesjavellir, iceland, october 13-15, 2002 (No. 3; SAGA Report). (2002).
⁴ A solution to our clean energy problem may lie right beneath our feet. (n.d.). Time. Retrieved August 7, 2020, from https://time.com/4844086/geothermal-energy-iceland-deep-drilling-project/
⁵ Where geothermal energy is found—U. S. Energy information administration(Eia). (n.d.). Retrieved August 7, 2020, from https://www.eia.gov/energyexplained/geothermal/where-geothermal-energy-is-found.php

Photo by Joey Clover on Unsplash

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Putting Artificial Intelligence to Work in the Power Industry

The moment I hit the ground, I knew it was broken. I was rock climbing with my wife the day before embarking on a weeklong canoe trip. Half-way up the rock face, I lost my grip and fell. I landed hard on my right foot, which immediately buckled and rolled. The pain was excruciating.

Rinda wanted to take me straight to the emergency room. I should have listened to her, but I knew that would be the end of our vacation. I also figured I wouldn’t do much walking in a canoe, so I quickly learned to hobble on one foot and spent the week canoeing down the beautiful Green river.

When we arrived back home in Atlanta, Rinda took me to the ER, where I got an x-ray. The result was not surprising. A fractured ankle and heel bone. What was a surprise was that my x-ray had been reviewed – not only by a radiologist – but also by a computer. Artificial intelligence is becoming as good at reading some types of medical images as well-trained doctors.

And it’s not just doctors and hospitals. These days, it seems that everywhere I turn people are talking about machine learning and artificial intelligence. Attending conferences, there’s no shortage of confident speculation about its disruptive and transformational potential for the power industry. Talking to OEMs and vendors, you’d think they’ve got the perfect AI solution to solve all your problems.

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