GE offers 6B repowering17 October 2018
GE has launched a repowering offer for its 6B gas turbine, coinciding with the 40th anniversary of the fleet, and secured its first agreement to implement the upgrade, on three machines at a chemical facility in Asia, promising significant fuel savings.
“This fleet is known for its dependability”, said Scott Strazik, president & CEO of GE’s Power Services business, “with global fleet reliability of 98.4%, but at the same time, the 6B fleet has aged, and there’s growing demand to improve performance.” The repowering offer and the recent extension of Advanced Gas Path (AGP) technology to the 6B fleet (see Modern Power Systems, July 2018, pp 12-16) highlights GE’s continuing investment in its mature fleets, says Strazik, to operators “remain competitive in today’s very dynamic marketplace.”
Part of what GE calls its Fleet360* portfolio of service offerings across the complete power plant, the new 6B repowering package incorporates elements of advanced F and H class gas turbine technology to elevate 6B performance to “leading levels for its class.”
The repowering consists of a full “flange- to-flange” upgrade of all major components, including the combustion system, hot gas path and compressor, effectively transforming the 6B into a 6F.01 gas turbine (part of GE’s current product range).
The repowered 6B, which fits into the existing 6B footprint, offers the following potential improvements: increased turbine output, up to 35% simple cycle/25% combined cycle; up to 5 percentage points efficiency improvement (simple and combined cycle); up to around $3 million in fuel savings per unit annually; NOx emissions down to 15 ppm; extension of hot gas path inspection interval to 32 000 hours (from 24 000 hours) and major inspection interval to 64 000 hours (from 48 000 hours).
6B – 40 years on
Today, over 900 6Bs are still in operation with 55% in continuous-running applications. The first unit, installed 40 years ago, was at Montana-Dakota Utilities’ Glendive power plant.
Currently, this unit operates during peak periods—in conjunction with extreme hot and cold conditions when more power is needed. “What we have benefitted from the most is the unit’s ability to adapt extremely well to the wide differences in temperature that are typical in Montana, that can span from -30 to 110°F”, said Darrin Holzer, manager of combustion turbines & wind generation, Montana-Dakota Utilities.
The 6B fleet has now accumulated more than 65 million operating hours. Over the years performance improvements have included:
- In 1991, introduction of DLN on the 6B, reducing NOx emissions to 25 ppm, along with more flexible operation, with lower turndown and increased fuel options.
- In 2000, output increase of 6% and efficiency increase of 0.5%.
- In 2009, 6B Performance Improvement Package, with improved materials, coatings, sealing and aerodynamics derived from F-class technology to further increase output and efficiency. PIP is currently installed on over 200 units and it has become the standard configuration for new 6B gas turbines.
- In 2011, first 6B flange-to-flange upgrade, at the SAICA (S.A. Industrious Celulosa Aragonese) paper mill in Spain. This achieved an over 13% increase in output, an 8% efficiency improvement, and over 10% more steam.
- In 2018, AGP upgrade of three 6Bs at Saudi Cement’s Hofuf power plant.