Gas-Turbine Upgrades Drive Improvements

EP Editorial Staff | December 19, 2018

GE’s upgrade of the 9E gas turbine at Sokolovska Uhelna’s Vresova power plant in the Czech Republic represents the first 9EMAx upgrade in Europe.

Power producers benefit from greater output and flexibility, lower fuel and maintenance costs.

Power plants around the world are aging, and operators are struggling to generate more electricity and reduce fuel costs while still turning a profit. In today’s dynamic and ever-changing market, power producers need their gas turbines to generate more output and burn fuel more efficiently, while delivering high reliability and operational flexibility. GE, Boston (, is paying close attention to these needs and delivering solutions, including the 9EMax.

GE’s 9EMax is an upgrade for the company’s 9E gas turbine. Part of the Fleet360 platform, it was developed using GE’s experience with a global fleet of more than 700 9E gas turbines and insights from more than 30-million hours of operating data.

According to the company, the 9EMax produces significantly more power, delivering incremental revenue generation, and has a higher efficiency than past offerings, which equates to millions of dollars in fuel savings. Additionally, power producers are said to be capable of reducing operating costs with extended planned-maintenance intervals and longer part life. The experience of Sokolovska Uhelna (Sokolovska), Sokolov (, one of the largest independent producers of electricity in the Czech Republic, is a case in point.

Sokolovska Uhelna turned to GE when it needed to upgrade a 9E gas turbine at its power plant in Vresova. GE’s Power Services business completed the installation, the company’s first-ever 9EMax upgrade in Europe, in Oct. 2018. From that point, GE’s combined-cycle capabilities and 9EMax’s performance have been exceeding Sokolovska’s expectations on heat rate, power output, and unit flexibility.

Assembly of GE’s 9EMax is shown.


Since its establishment nearly 25 years ago, Sokolovska Uhelna has invested heavily in upgrading its units with the latest technology GE can offer. The upgrades build on Sokolovska’s rich historical tradition of mining and refining of brown coal in the Sokolov region. Its main products are electricity, heat, energy coal, and carbochemical products.

Among other things, the company extracts about 7-million tons of lignite annually, out of which 50% is used for its own process to produce syngas for integrated gasification combined cycle (IGCC) to power its own mining and industrial processes, as well as those of other power-generation customers in Europe.


“Our two existing GE 9E gas turbines were reaching the end of their design life, and we evaluated many different scenarios,” said Pavel Homola, director of the Sokolovska Uhelna Processing Division and member of the board. “We have worked with GE for more than 20 years, and we’re confident in the technology and trust GE’s expertise, so we turned to them to help us find the right solution. After examining operating and capital expenditures, we determined GE’s 9EMax upgrade was the best option for our plant to improve the 9E gas turbine’s performance and flexibility as well as to lower the operation and maintenance costs for the upcoming 20 years life-cycle period.”

As part of the 9EMax upgrade project, GE also performed a complex rotor repair and fast stator rewind of two of its T240-370 generators to extend the equipment lifetime and improve the entire gas plant’s performance and reliability. The upgraded unit also was equipped with GE’s online monitoring system and connected to its Monitoring & Diagnostics Center in Atlanta for 24/7 predictive-maintenance support.

This 9EMax was manufactured at GE’s Manufacturing Center of Excellence in Belfort, France.

“Due to GE’s extended scope capabilities and overall excellence in execution, the 9EMax upgrade of the first unit was completed smoothly and exceeded our expectations on performance. In turn, this will allow us to be more competitive on the electricity and grid services markets in Europe,” said Homola.

Specifically, GE’s generator rotor repair and stator upgrades at the Vresova power plant allowed an increase of output by implementing the latest stator bar technology and associated insulation material.

The upgrade also improved stator robustness toward potential cyclic duty operation through an improved end-winding support system and associated wedging. GE improved stator bar clamping and reduced the risk of electrical sparking by implemeting the latest rewind technology and installation processes. They also improved rotor reliability by using the latest insulation technology and rewind process.

“We worked with Sokolovska to find the right solutions to meet their needs on this first 9EMax European upgrade,” said Scott Strakik, president and CEO of GE’s Power Services Division. “We know our total plant-services solutions and technical expertise in combined-cycle power plants was essential to successfully modernizing this very important plant in only ten weeks, something that was absolutely crucial for Sokolovska Uhelna.” EP

The GE 9EMax (or 9E.04) is a four-stage version of the company’s three-stage 9E.03.

Delivering the Future Now

GE’s 9EMax delivers as much as 37% efficiency and 145 MW of output in simple-cycle operation, and as much as 53.5% efficiency and 210 MW of output for combined-cycle operation. Its 9EMax maintains the 9E gas turbine’s proven reliability and enables as many as 32,000 hours/900 start maintenance intervals.

In 2017, TEPCO Fuel & Power, Tokyo (, became the world’s first 9EMax operator. At the company’s Futtsu power plant in Chiba, Japan, GE has already completed four of six 9EMax upgrades to boost combustion efficiency by 4.2% (from 47.2 to 51.4%), as well as increase power output.

TEPCO is implementing the 9EMax upgrade solution to extend the life of the 32-yr.-old 9E combined-cycle gas turbines, while improving gas-turbine efficiency and output and maintaining the original footprint of the existing units. The Futtsu Thermal Power Station, one of TEPCO’s defining facilities, is a massive power station housing four groups with combined-cycle systems. As the first operator in the world to implement 9EMax into their fleet, TEPCO also allowed GE to successfully conduct the necessary prototype testing (validation testing) at Futtsu Thermal.

“The way electricity is used shifts dramatically with changes in the economy, technology, and the industrial sector; causing things like fluctuations of frequency, changes in load between day and night, and changes in the demand curve in general. In the face of all this, power stations must be even more flexible in adapting to the changing demand for each type of electricity. Therefore, we are especially fascinated that 9EMax has such an advanced daily start-stop system,” said Kenji Nakamura, manager of Futtsu’s gas-turbine replacement group and onsite manager for the project.

“Throughout all those years of intense operation, there were never any major malfunctions, so we knew that was a reliable piece of equipment. Reliability was one of the deciding factors for us in choosing the 9EMax and an important factor because it brings significant impact on operation costs. Generally, the recommended frequency of inspection for equipment of this scale is once every one to two years,” Nakamura explained. “The 9EMax, however, can get away with a maintenance interval of once every four years [assuming typical operating loads, and roughly speaking, a maximum of 900 starts, and 32,000 operating hours].”

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