GE’s GT26 HE Upgrade

GE announced the upgrade of a GT26 gas turbine with its High Efficiency (HE) package that allows to reach higher efficiency, increased power output and longer maintenance intervals.

It is the first F-class gas turbine that GE will upgrade to H-class performance levels at over 60% combined cycle efficiency. The gas turbine is part of a combined-cycle power plant in Enfield, UK, operated by the international energy company Uniper.

Michael Rechsteiner, GE’s vice president Power Services Europe, said that the project with Uniper is a clear indication of how GE continues to invest to improve mature technology.

According to Rechsteiner, market dynamics especially in Europe have changed dramatically in the past few years. Some major shifts in the energy market, such as the rise of renewable power, the move away of some countries from nuclear, and the decrease in the use of coal as a fuel, force the operators of large gas-powered power plants to forget about baseload operation and cope with a need for more flexibility. “Most of our customers switch the power plant on at least once a day; sometimes even twice a day,” he said. “This is why increasing the flexibility of operating gas turbines is a must.”

Rechsteiner said there are about 100 GT26 gas turbines in operation today, and more than half are located in Europe. With an average operating life that falls between 10 and 20 years, all these units are good candidates for an upgrade in efficiency and power output. “Imagine that, if all these gas turbines were upgraded with our GT26 HE package, we would add approximately between 2 and 3.3 GW output – that is the power needed for a metropolis such as Paris,” he commented.

This upgrade features some unique engineering elements developed by a team of 200 engineers between GE’s research and development centers in Switzerland and USA. Simone Serges, GT26 senior product manager at GE Power, explained: “In the upgrade we utilize a low-pressure turbine that incorporates some of the most advanced technologies used in our H-class fleet. It features improvements in internal cooling, thermal barrier coating such as dense vertically cracked (DVC) coating and includes key learnings from the GT26 specific experience in terms of durability.”

“As for the high-pressure turbine, we use technology from GE’s F-class to increase efficiency,” he added.

A new 3D aero-profile compressor configuration is also used to improve base-load and part-load performance. “The second combustor incorporates additive manufactured (AM) parts that reduce cooling requirements by approximately 15% and lower relative emissions thanks to the improved mixing.” Serges said.

The GT26 HE upgrade allows to reach a 2% baseload increased efficiency for combined-cycle power plants, which translates into about US$4 million in fuel savings annually per unit, according to Rechsteiner (depending on values such as yearly operating hours, yearly full load hours, fuel price and electricity price).

In part load, the increased efficiency reaches up to 1%, or up to US$1 million in fuel savings a year per unit.

The plant output can be increased from 15 up to 55 MW per unit, and inspection intervals can be extended up to 32 000 hours, increasing availability and reducing long-term maintenance costs.

Rechsteiner said that the Uniper’s Enfield power plant in London will be the first site to install the new GT26 HE technology in 2020. The combined-cycle plant is about 20 years old and at the beginning the plant worked in baseload; in most recent years though it had to work intermittently.

This first upgrade project is for one unit, but Rechsteiner said there will likely be plans for upgrading other turbines as well. The customer seems to be very pleased: “The opportunity to test GE’s pioneering GT26 HE upgrade at our Enfield plant, combined with our longstanding relationship with GE and trust in its technology and services were key reasons we chose the company for this project,” said Mike Lockett, chief commercial officer, power, for the Uniper Group and Uniper U.K. country chairman.

“In Great Britain’s very competitive and challenging power generation environment, investing to keep our plants competitive by lowering operational and maintenance costs at the same time as increasing efficiency and flexibility is critical for the long-term success of our fleet,” said Eckhardt Rümmler, chief operating officer, Uniper SE.