501G USERS GROUP: 2019 recap and 2020 updates – Combined Cycle Journal

501G USERS GROUP: 2019 recap and 2020 updates

The 501G Users Group traditionally has conducted two meetings annually, the first early in the year, the second about six months later. For many years, the winter meeting was held in the same venue and at the same time as the 501F Users Group’s annual conference, the organizations coming together on safety, presentations by third-party suppliers, vendor fair, and meals.

The G users hosted winter meetings on their own from 2016 through 2019 but decided to rejoin the 501F users in 2020 because of the benefits that accrue from having a larger group of owner/operators sharing experiences. The 501G summer meeting will be conducted during the Siemens Customer Conference for F, G, and H Technology, as it has since 2016. The summer meeting, hosted by Siemens, will be held at the Renaissance Orlando at SeaWorld, the week of June 15. It will be co-located with the T3K Annual Conference.

501G Users Group steering committee

Chair: Steven Bates, plant manager, Wise County Power Plant, Vistra Energy
Vice Chair: Mark Winne, plant manager, Millennium Power Partners (operated by NAES Corp)
Scott Wiley, outage manager, Vistra Energy
Guy Taylor, plant engineer, Lakeland Electric
John Wolff, technical support/compliance manager, Ironwood, LS Power

The G Users Group is a small, but proud organization of engineers and technicians who have “grown up” together—so to speak—and understand each other’s perspective. The first G, installed by Lakeland Electric, began commissioning operations in April 1999, but COD wasn’t until March 2001—only one month before the second machine began commercial operation at Millennium.

Fleet size is small by industry standards—24 Siemens (Westinghouse) engines at 13 sites in the US and one in Mexico (sidebar). Four plants are equipped with one engine each; seven have two gas turbines; two are equipped with three machines each, arranged in 1 × 1 combined cycles.

W501G fleet: 13 plants, two-dozen units

  • Ackerman Combined Cycle Plant, TVA, Ackerman, Miss
  • Athens Generating Plant, Talen Energy (operated by NAES Corp), Athens, NY
  • Ennis Power Plant, Vistra Energy, Ennis, Tex
  • Fuerza y Energia Naco Nogales SA de CV (FENN), Gas Natural Fenosa México, Agua Prieta Sonora, México
  • Granite Ridge Energy Center, Calpine Corp, Londonderry, NH
  • Harquahala Generating Facility, operated by NAES Corp, Tonopah, Ariz
  • Hillabee Generating Station, Exelon Power, Alexander City, Ala
  • Ironwood, LS Power (operated by EthosEnergy Group), Lebanon, Pa
  • Magic Valley Generating Station, Calpine Corp, Edinburg, Tex
  • Magnet Cove Generating Station, Arkansas Electric Cooperative Corp, Malvern, Ark
  • C D McIntosh Jr Power Plant, Lakeland Electric, Lakeland, Fla
  • Millennium Power Partners, Talen Energy (operated by NAES Corp), Charlton, Mass
  • Wise County Power Plant, Vistra Energy, Poolville, Tex

User meetings typically host roughly one-third to one-half first-timers, so many discussions are similar from year to year because newcomers have to be brought up to speed. There’s not much turnover in the top positions at G facilities which means each meeting pretty much picks up where the last one left off, especially regarding the OEM’s presentations. This certainly contributes to presentation efficiency because there’s a minimum amount of repetition.

Most users groups serving GT owner/operators organize their technical programs by sections of the engine—for example, compressor, combustion section, turbine, etc. The G users begin with an “annual report” from each plant and follow that half-day program with user presentations on emerging and significant plant-wide issues of importance to the fleet. Notes taken during the plant reports at a recent meeting follow:

Plant 1 with three 1 × 1 combined cycles reported on the steps considered for the layup of one unit because of low demand—something affecting many power producers nationwide. Two units suffered Row 1 turbine-blade failures in the previous six months and one of the steam turbines required replacement of L-0 blades.

Plant 2 found TBC (thermal barrier coating) loss on two R2 vanes during the borescope inspection of one of its two engines and replaced them. A R1 vane was replaced in the sister unit as well. At the time, both machines had operated for less than 40k equivalent baseload hours (EBH) and had fewer than 900 equivalent starts (ES).

Plant 3 found damage to Row 1 turbine blades during a borescope examination at about 90k EBH and fewer than 1000 ES, replacing the entire row and five transition pieces during a modified hot-gas-path (HGP) inspection. A hot-reheat tube failure in the HRSG also was noted.

Plant 4 took a major early to deal with a broken through-bolt and compressor hook-fit wear on one of its two gas turbines. A steam-turbine major for this 2 × 1 facility included rotor replacement and new bolting for the low-pressure cylinder. Generators were re-wedged.

Plant 5 reported on the HGP and generator major conducted for one of its two units, plus its experience during a steam-turbine valve overhaul.

Plant 6 was forced into an economic shutdown and shared key aspects of its layup plan.

Plant 7, with two engines having slightly more than 80k EBH/1750 ES, presented its experience conducting a double combustion inspection for the first time, and replacing Row 1 vanes. Also shared were plans for installing NextGen hardware during an upcoming outage.

Plant 8, a 2 × 1 combined cycle with just north of 50k EBH/700 ES on its gas turbines, spoke about a CI on Unit 1 that went to a modified HGP and included replacing four Row 4 blades. Balance shots also were installed to reduce vibration. Unit 2 required an HGP, plus rotor removal to address seal issues. New R1 NextGen vanes were installed. In addition, HP and IP valves and actuators were replaced on the steamer.

Plant 9, approaching 100k EBH/2700 ES on its 1 × 1 combined cycle, shared details of a lost-time accident and replacement of the gas-turbine generator’s step-up transformer. The speaker said the following were on his mind: turbine through bolts, HRSG fouling and its impact on gas-turbine backpressure, and Row 1 blades and vanes.

Plant 10, a 2 × 1 combined cycle, reported on the replacement of the exhaust expansion joint for one of its gas turbines and on SCR catalyst replacement in the HRSG for that engine. A steam-piping crack was mentioned as well.

Plant 11 said its gas turbine was closing in on 100k EBH and 2750 starts, reporting that the unit was running well. The only hiccup was rotor-air-cooler leakage at the inlet tubesheet which required plugging six tubes. The takeaway: probably time for a replacement tube bundle.

Plant 12 borescoped its gas turbine and received a clean bill of health.

Plant 13 had nothing but good news to report since the previous meeting. Planning was underway for majors on both of its gas turbines in the following year.

The open discussion portion of the meeting began with safety topics, including the following:

  • Outage planning. Consider outsourcing confined space rescue; one plant reported this as less expensive than using staff. A user suggested bringing in colleagues from other facilities several weeks prior to an outage to review and comment on your plans and procedures. Might also be a good idea to bring in representatives from selected contractors for the same purpose. To police for safety violations during the outage a user suggested hiring an outside contractor experienced in this work.
  • Grinders/saws/buffers. Be aware that grinding wheels can explode (don’t forget face shields) and that any rotating cutting/grinding tool has a “coast-down” time during which it remains hazardous to operators and others in the work area. One attendee said he surveyed some of this plants tools and found coast-down times of 11 to 17 seconds. Unacceptable!. Quick-stop tools are available and they cease rotating in 1 sec. A contractor contacted after the meeting suggested to the editors that reciprocating saws are an alternative to centrifugal tools. They’re safer, he said, but they take longer to make the cut and the cut is not as clean as with centrifugal tools.
  • This is an area that begs for experience. Many experienced riggers have retired and the number of reported near misses and dropped rotors is increasing and very concerning. Be sure no personnel are under any lift and that ground and crane people are in constant contact during the lift, and that the component being lifted is visible for the entire lift.
  • Color coding. Have vests and/or hardhats of different colors to facilitate identification of critical personnel and to be sure the proper person is working on a particular issue. Example, one color for riggers, one for confined-space rescue, etc.
  • Identify near misses during the outage, get RCAs done quickly and circulate findings among all who should know about them.

User presentations/discussions focused on turning-gear preventive maintenance, a main relay protection failure and findings, high-vibration trip and findings, and a few other topics. Such discussions often morph into self-help clinics with colleagues offering the benefits of their experiences to anyone who has a concern and is unsure of what he/she should do given a particular set of circumstances. In some cases, users share experiences for “awareness” purposes—situations to avoid, and why. Learning from the experiences of others is a primary goal of all users groups. Avoid mistakes already made. CCJ

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