GE Power believes that oxidation woes involving its family of HA turbines have been overblown in some quarters and the company vows it is fully behind what it considers the “crown jewel” of its power portfolio.

“It’s our best product is still the fastest growing,” said Guy DeLeonardo, product manager—advanced gas turbine platforms at GE Power. DeLeonardo and his team at GE led the launch of the HA family. “It’s also the fastest growing segment in the industry and yes, it’s an attractive profit pool for us and the industry both from on a new power plant perspective as well as services because of its advanced technology. So all those things still rank true.

“It’s absolutely still the case that it’s the crown jewel of our product portfolio…And it’s key to the future of energy.”

The first high-efficiency air-cooled (HA) gas turbine combined cycle power plant was inaugurated in 2016. The first 9HA.01 entered commercial operation (COD) in the summer of 2016 at EDF’s Bouchain plant, located in the Nord Pas-de-Calais region of France. Efficiency of this plant is 62.22% on a net combined cycle basis while producing more than 605 MW of electricity.

The company has received 83 HA turbine orders, with 30 in commercial operation. DeLeonardo said GE booked five HA orders in the last quarter—the only OEM to book orders in that range.

In June 2017, GE installed two 7HA.02 gas turbines at each of Exelon’s Wolf Hollow and Colorado Bend power stations in Texas, USA. In early September, DeLeonardo said a stage one blade “liberated” from one of the turbines, forcing the plant to shut down.

“This particular oxidation issue that I mentioned is, a cold oxidation mechanism that happens inside the blade,” DeLeonardo said. “It had nothing to do with the temperature of the machine, which is really one of the primary factors in driving its efficiency.”

He said the as the cooling flow, passes over the shank of the blade, there’s an oxidation attack of that surface that creates a crack and the crack propagated.

“It’s not anywhere near the traditional mechanisms–you’ll hear of low cycle fatigue creep and whatnot that are active in the hot part of the airfoil and all those mechanisms are driven by temperature and you need the right coatings and all these kinds of things,” he said. “So it’s a new phenomenon for the industry.”

GE had seen the issue in two 9FB units as early as 2015. The company had found a fix for the problem and was rolling it out through the affected products, including the HA line, DeLeonardo said.

The solution is relatively straightforward.

“We didn’t change any casting, we didn’t change cooling,” he said. “At the casting house, we changed how it is heat treated to get the right micro-structures to make it robust. So that was all understood on the 9FB and that’s what’s been implemented in the update to the stage one blade and that’s what’s making its way through all active operating engines as well as the factory changeover.”

Exelon’s Wolf Hollow power plant. The company had two 7HA gas turbines at that plant and two more at the Colorado Bend facility. In September, both of the power plants were shut down after an event related to a turbine component.

Exelon said it was satisfied with GE Power’s response.

“Following the event, GE advised us to take the remaining three units offline for the change out of the blade,” the company said in a statement. “GE quickly mobilized the teams and equipment to sites, and today all four units are back online. We feel confident about the replacement product.”
“The GE HA gas turbine represents a great technological innovation. And with any new technology in our industry – especially something as groundbreaking as the HA – there is an expectation that adjustments will be made along the way. GE’s response has been quick, thorough and consistent. We look forward to continuing to work together with GE for many years to come.”

Word of the problem at Exelon trickled out from a users’ conference in September and was picked up by the general media. The problem was reported, but DeLeonardo said the fact that GE Power was on top of it—and that issues with sophisticated, advanced technology are not uncommon—was missed.

“Here’s what I would say—yeah, it’s over sensationalized,” DeLeonardo. “It’s more negative press than we think it is certainly warranted. We’re completely confident in what we’re doing, how we’re doing it. We still continue to, to win, you know, half the half the orders that go off in the space.

“Are there things like a liberation event that we’re not happy with? Absolutely. It’s ugly. Right?” he said. “But it doesn’t detract from what the machine is doing, (that we have an) address for it, the continued progress in orders, commercial operation, availability, reliability.

He said GE Power is well-experienced in launching advanced technology—they’ve been doing it since the 1940s. The company’s F class, which came out in 1986, now has the 70 million hours of operation—but there were teething issues that had to be worked through, he said.

“And I would say we know how to recognize those problems and solve them as well,” he said.

Much of that work is done at GE Power’s Greenville, South Carolina, USA facility, which the company said is the most powerful off-grid gas turbine validation facility in the world.

“It’s a compressor test facility as well as gas turbine test facility and we were able to map the compressor and the gas turbine well beyond what it would see in operation to have been tested,” DeLeonardo said. “We were able to map the compressor well beyond what the gas turbine would ever see an operation and then measure it right and analyze it in a way that we were looking for all the types of teething issues we had learned on the F class.”

Along with the validation in Greenville, GE also does rigorous fleet leader inspections, he said.

“There’s still field testing going on. And so as we looked at that data and we saw the sort of things we didn’t like,” he said of the HA turbines. “That’s all part of launching new technology and built on the experience that we have—we’ve been doing this for the last 80 years. So we were out in front of this with existing operators and now from a potential customer.

DeLeonardo agreed that the turbine issue probably got more coverage than it would otherwise receive because of the ongoing challenges GE faces overall.

“Clearly, clearly there are a lot of dynamics, if you will, around the business—financially, stock-wise, leadership-wise,” he said. “And so now you look at this and it’s like, ‘Oh, you have a field issue where you’re cutting corners’ these kinds of things.”

He said the company cut no corners introducing the HA and said they have exceeded performance metrics at every site and are achieving strong reliability figures that continue to get better. GE Power is still expecting the turbine to achieve 65% efficiency by the early 2020s through ongoing improvements in materials, combustion cooling and sealing advancements.

“We are still determined on the continued development of the HA product line, the technologies that go into that, that continued to improve its economics and its path to 65% efficiency,” DeLeonardo said. “We have a full address for this particular issue as we always have and will continue to do so.”

–Jack Burke

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