If there were a "comeback award" for user groups serving the gas-turbine-based power and process communities, as there is in sports, it most certainly would go to the Frame 6 Users Group. This group met annually from 1986 through 2000, but interest waned as the machine matured and users thought most issues had been resolved. Budget cuts adversely impacted corporate support and participation by GE Energy, Atlanta, and no meetings were held in 2001, 2002, and 2003.
Last year, California-based Foster Wheeler Martinez sponsored a conference in Las Vegas with the goal of revitalizing the group as a self-funded organization. The Frame 6 Users traditionally had been supported by large industrial companies that owned and operated 6B engines-such as Amoco Chemicals, ExxonMobil, BASF, Celanese, etc.
Participants at the 2004 meeting responded positively and a steering committee was formed. Larry Flashberg, plant engineer, Saguaro Power Co, Henderson, Nev, and Jeff Gillis, senior staff engineer, ExxonMobil Chemical Co, Baytown, Tex, were elected co-chairmen (see sidebar, p 130, for names of all committee members). To ensure success as a self-funded entity, the group brought Wickey Elmo (704-753-5377, email@example.com) onboard as conference coordinator. Elmo has years of experience managing user groups.
It was a formula for success. The 2005 meeting, held the last few days of August in Houston as Hurricane Katrina was pummeling the Gulf Coast to the east, drew just under 100 user attendees-a number some other groups would envy. More than half of the users came from refineries and chemical plants, some from far-off lands-including Nigeria and Oman.
The mission of the organization is to provide members an open forum for dialog and exchange of information to improve O&M practices related to GE Frame 6B series GTs and to interface with the manufacturer regarding generic issues with the 6B fleet. For information on participation in this user group, access www.frame6usersgroup.com.
Group objectives certainly were met in Houston. In fact, it's probably fair to say that the meeting exceeded expectations. However, whether the Frame 6 users know how to relax is open to debate after the Houston experience. Serious activity was non-stop from the time Elmo's registration desk opened at 4 pm Sunday, August 28. Well, that's not exactly true: There was a relaxing welcome reception sponsored by ACT Advanced Combustion Technology Inc.
Then the serious program started. Most user groups feature golf on the first day, or have a tour of a local attraction. Not Flashberg/Gillis and company. What do they do for fun on a Sunday evening? Visit a repair facility. At 8 pm a bus ferried three dozen or so attendees from the comfortable South Shore Harbour Resort and Conference Center in League City to ACT's shops near Hobby airport. As crazy as it sounds, it was the ideal time for a productive visit-no phones ringing, no other interruptions.
Plan ahead: 2006 annual conference
The Frame 6 Users Group steering committee announced at the Houston meeting that the organization's 2006 conference will be held June 12-15 in Phoenix. Contract for the meeting facility had not been signed by press time. Delegates and exhibitors with interest in attending should access www.frame6users group.com for the latest information. Or, contact Wickey Elmo, conference coordinator, at firstname.lastname@example.org or 704-753-5377.
President/Operations Manager Joe Cosart and his entire senior staff were available to present ACT's facilities, explain the processes the company uses for repair and refurbishment of various turbine components, and answer any questions (sidebar, p 125).
It was approaching midnight when the bus returned. But there was no aftershock; the breakfast room was full at 6:30 the next morning. With Elmo directing the kitchen, everyone eats well and few meals are missed. Flashberg and Gillis called the meeting to order an hour later and the users went flat out for the next two and a half days-including eight prepared presentations and 13 roundtable discussions. So much material was covered during the meeting that the editors had to split their coverage into two articles. This one focuses only on the prepared presentations. A followup feature (next issue) will provide an overview of the roundtable discussions.
There were only about a dozen attendees along for the Sulzer Hickham facilities tour and that was unfortunate-much to see, much to learn. But the visit to this world-class repair facility was scheduled on the last afternoon of the meeting in the aftermath of Hurricane Katrina and many attendees had to rush home.
Hickham is an impressive success story. The company was established in LaPorte, Tex, in 1974. It was purchased by Switzerland's Sulzer in 1985 as a wholly owned subsidiary. Annual revenues were about $6 million and employees numbered 60 at that time. By the millennium, revenues had grown 10-fold, employees six-fold.
Frame 6 users saw a little bit of just about everything-and that took nearly three hours. Too many questions, perhaps, for a willing host to answer. Blade/airfoil manufacturing and repair, gas- and steam-turbine repair shops, at-speed rotor balancing facility, machining and welding centers, coating shops, metallurgical lab, and NDE centers all were stops on the tour.
Frame 6 users share a light moment at fixture to hold transition pieces during rework (left). Kyle Todt of Sycamore Cogen is at left. Moving right: Larry Flashberg, Saguaro Power; Olaf Barth, Dominion; Nile Jackson, Saguaro Power; and Homer Boswell, Dominion. At right is a Frame 6 rotor in the final stages of overhaul
The first full day was capped by a vendor fair (see pages 126-129 for profiles of most participating companies) and reception, the second by the Frame 6 Dinner. Both went until 9 pm. Final event of the 2005 meeting-after lunch on the third day-was a visit to Sulzer Hickham's repair and overhaul facilities in nearby LaPorte (sidebar, above).
It's tough enough getting commitments from eight speakers, let alone getting eight solid presentations. But the Frame 6 steering committee got the results desired. With many users concerned about meeting emissions regulations that are being ratcheted down in many parts of the country, Clay Moran's presentation showed just how low you can drive NOx emissions with commercially available equipment.
Moran, director of Power Systems Mfg LLC's combustion product line, reported on experience with the company's low-emission combustor (LEC)-specifically the LEC III. Moran said that PSM, based in Jupiter, Fla, is the only after-market company with a proven DLN (dry low-NOx) combustion system for GE Energy's Frame 6B installed base. The company offers complete upgrade kits to "easily replace" standard combustors or factory-installed low-NOx systems to the LEC III, which comes with a 16,000-hr inspection- interval guarantee (figure, p 123).
The 6B field experience to date has been with a gas-only LEC III. However, Moran told attendees that PSM has developed a dual-fuel LEC for the 6B which also is guaranteed to operate at less than 5 ppm NOx on gas. It has additional liner features and water-cooled liquid-fuel distributor valves to ensure reliable operation on distillate. The combustion system is ready for field implementation, he said.
Results of validation-rig tests, high-time operational hardware condition, and instrumented engine data, reported Moran, combine to prove system reliability and performance are equivalent to the OEM's (original equipment manufacturer) DLN-1 offering, except that PSM's LEC III is capable of much lower emissions.
He presented a chart that summarized operating experience. It listed a half-dozen 7EA, 6B, and 7B-to-E machines in service with LEC III "drop-ins." The five most recent installations (installed 2003-2005) are operating at below 5 ppm NOx and 2 ppm CO. The sixth, the first commercial LEC III system, installed in 2001on a 7EA, is running at under 6 ppm NOx and under 2 ppm CO.
Of particular significance to the Frame 6 users was Moran's data that showed emissions deterioration has been minimal, if any. The data stream, from Dow Chemical's Seadrift (Tex) facility, showed the drop-in system achieving 4 ppm NOx and 9.6 ppm CO when it went into service in March 2004. Unit was producing 38.5 MW at the time of the test; exhaust temperature was 1019F, exhaust spread 49 deg F. In June 2005, emissions of 4.05 ppm NOx and 4.19 ppm CO were recorded with the unit operating at 32.7 MW. Exhaust temperature was 1051F and the spread 43 deg F. Note that Seadrift is the Frame 6B fleet leader with more than 11,000 hours of service. Currently there are three 6B units operating with the LEC III; another will be starting up shortly.
PSM's vision is to get to a guaranteed 2.5 ppm NOx to compete with SCR (selective catalytic reduction) head-to-head. Moran acknowledged that technology application will vary in complexity from site to site. He also mentioned that NOx reduction by use of "blended fuels" is under development.
Moran said that key features of the LEC III include a pilotless secondary fuel nozzle and complete elimination of diffusion combustion. Additionally, the head end is a greatly enhanced premixer because of air-flow distribution changes. Less air is used for wall cooling because of the efficiency of effusion cooling, so more air is available for mixing. This arrangement is key to maintaining a near-uniform temperature profile in the reaction zone of about 2700F thereby eliminating the hot spots (temperatures of 3500F) that drive up NOx production.
Improved manufacturing techniques also contribute to a more uniform temperature profile by minimizing the flow variation from liner to liner, he continued. Engine hot streaks are virtually eliminated and exhaust temperature spreads have been reduced from a typical 60 deg F to the 30s or 40s-as the Seadrift data confirm.
The company's combustion liner was redesigned so that the venturi is arranged in a forward-flowing cooling-air configuration. This patented technology, Moran said, "has proven to be a tremendous CO reducer." All of the venturi cooling air discharged is collected in an outside plenum surrounding the liner and reinjected into the liner head end. Venturi air is preheated, becomes part of the premixer, and is completely used in the combustion process.
In the OEM's system, by contrast, the aft-flowing cooling air is discharged as a cold unmixed stream that surrounds the reacting gases. As a result, a significant amount of CO is "locked in" and prevented from forming CO2.
PSM's liner design also benefits from the latest analysis tools to achieve greater durability, Moran continued. Wear-resistant materials at critical interface locations help minimize loss of fit-up. This also is a key system feature to assure minimum deterioration.
Matthew C Lau of Sulzer Hickham's Component Div, LaPorte, Tex, spoke on a subject of tremendous importance to anyone in the competitive power business: Maximizing the life of critical components. First-stage nozzle restoration was the example presented.
Lau began with the question he often is asked by users: "What is the life of my critical components?" The general perception in the industry, he continued, is that once a Frame 6 first-stage nozzle operates for a certain number of hours it no longer is serviceable. This is true, Lau said, but nozzle life often can be extended with correct restoration.
One of the most critical factors in determining remaining life is the metallurgical state of the nozzle segment, which is cast from the cobalt material FSX414 and is subject to alloy depletion. Reason alloy depletion is important is that it can affect the weld capabilities of the nozzle. Corrosion and oxidation erosion cause thinning of base material, but surface coatings can be applied to help extend the life of that material.
Another consideration in component life assessment is the dimensional disposition of the nozzle assembly. Installation and operational problems occur when it becomes distorted/deformed, adversely impacting unit performance. Dimensional distortion can start a cascading effect that ultimately shortens the life of the nozzle assembly.
President/Operations Manager Joe Cosart greeted the Frame 6 users at the entrance to ACT's facilities in the shadow of Hobby airport. Outside it was pitch black, not much of a moon. Inside ACT's comfortable climate-controlled main shop it was like high noon. Shop? It's more like a clean-room facility used to machine parts for the space program. No, Cosart didn't have his workforce "turn-to" with the expectation of impressing visitors. The shop looks the same in the middle of a work day. It reflects Cosart's meticulous nature and is conducive to quality work in the demanding business of gas-turbine component repair.
ACT is a 10-yr-old company with more than 35,000-ft2 of shop space dedicated to the repair and rejuvenation of nozzles/vanes, blades/buckets, transitions, liners/baskets, etc-and growing. Most recent addition is a state-of-the-art fuel-nozzle flow test and repair facility capable of servicing components from GE's Frame 5s through 7FA+e machines as well as those from many engines built by Westinghouse. This facility is in a new 15,000-ft2 building that also accommodates a bid walk and job preview area complete with customer office and meeting center. For details, visit www.gasturbinerepair.com.
ACT's Joe Cosart, at far left, explains vane repair procedure to Union Carbide's Larry Hamilton, Petroleum Development Oman's Talal al-Mahruqi, UK-based NPower Cogen's Ian Gaunt and Steve Hicks, and Saguaro Power's Larry Flashberg (l to r). In photo at right, Chevron's Mike Wenschlag, Mike Popp, and Ruben Lopez (l to r) inspect repaired blade
Incoming inspection is where many potential problems are identified. Here's what is done in the Sulzer Hickham shops after parts are unpacked:
- Perform "typical" incoming inspections-liquid penetrant, ultrasonic testing (UT), metallurgical, weld capability, and dimensional.
- Review each segment while in an assembled state to identify potential problem areas within the assembly.
- Measure inner and outer sidewall joint gaps; inconsistencies can be a sign of underlying problems.
- Run assembly through an inner-support-ring simulator to quantify the amount of individual segment distortion.
- Set up each segment on a flat table and measure twist and distortion.
Lau presented individual slides to show the location of UT testing, how retaining-ring repairs are made, how flatness is corrected, steps in the complete weld repair process, etc. His handout is a valuable "how to" for writing specifications, evaluating alternative repair facilities, and for following future work.
Conclusions of the presentation were these:
- Full dimensional restoration can help extend the lives of the nozzle assembly and all affiliated components-including transition pieces, inner support ring, shrouds, etc.
- Full heat-treatment rejuvenation (solution anneal, stress relief, etc) can restore most materials and their mechanical properties.
- A fully restored nozzle generally has a reduced scope of repairs on subsequent cycles, thereby reducing costs.
Hans van Esch of Houston-based Turbine End-user Services Inc (TEServices), who has more than two decades of experience in the repair of GT components-including several years at Sulzer Hickham-followed Lau on the program (email@example.com). While he overlapped some of Lau's presentation on incoming inspection, van Esch started "at the beginning," suggesting how users might assess the condition of their GT parts onsite and use this information to prepare meaningful component repair specs and then select the appropriate repair vendor for their particular situation.
Frame 6 Users Group steering committee
Co-chair: Larry Flashberg, plant engineer, Saguaro Power Co, firstname.lastname@example.org.
Co-chair: Jeff Gillis, ExxonMobil Chemical, email@example.com.
Scott Berry, plant manager, Anderson and Richmond powerplants, Indiana Municipal Power Agency, firstname.lastname@example.org.
Homer Boswell, supervisor of maintenance, Rosemary Power Station, Dominion Virginia Power, email@example.com.
Brian Walker, manager of maintenance, Foster Wheeler Martinez Inc, firstname.lastname@example.org.
Zahi Youwakim, Huntsman Corp, email@example.com.
Justice could not be done to van Esch's thorough handbook-type presentation in a few hundred words here. A better approach is to read the first of a series of articles on the subject of his presentation, "Six steps to successful repair of GT components," which appeared in the 2Q/2005 edition of the COMBINED CYCLE Journal (CCJ, www.psimedia.info/ccjarchives.htm). It covers onsite parts assessment and specification preparation. The third step, selection of an appropriate repair vendor, is detailed in the 2006 OUTAGE HANDBOOK supplement to this issue beginning on p OH-7.
The remaining steps in the repair process-vendor verification of incoming inspection, repairs, coatings, and final inspections-will be addressed in detail in the 4Q/2005 and 1Q/2006 issues of the CCJ.
Charlie Pond of Pond and Lucier LLC (www.pondlucier.com), Clifton Park, NY, conducted a meaningful tutorial on outage planning, including the identification of outage issues, that was tailored to the Frame 6 fleet. His presentation, a handy guide for any 6B owner/operator, will be part of the conference proceedings to be compiled on a CD and offered for sale by the user group (write Elmo at firstname.lastname@example.org for details).
Here is Pond's 15-step procedure for planning and organizing a successful outage:
- Identify the job scope and date-for example, combustor inspection (CI), hot-gas-path (HGP) inspection, major inspection, generator inspection, system maintenance, etc.
- Make a spare-parts list. Don't forget fuel nozzles, crossfire tubes and retaining clips, combustor liners, gaskets, new fasteners, etc.
- Order parts early. Make sure you fully understand the supplier's system for doing this to avoid heartache later. Order parts early to get the best price. Don't forget the expendables such as rags, duct tape, plywood, etc.
- Decide how to perform the outage-for example, long-term service agreement, turnkey, hire technical advisor and labor separately, train staff and do internally.
- Plan, plan, plan. Select a commercially available critical-path software package to do overall planning and then fine tune by brainstorming internally to identify ways to shorten the total length of the job.
- Identify ways to shorten critical tasks.
- Analyze the OEM's TILs (technical information letters) and decide which to do, skip, or postpone.
- Review possible upgrades/uprates and decide which to do, which to postpone or skip. Don't forget to evaluate the impact of any GT improvement on other plant equipment-such as the heat-recovery steam generator (if installed), generator, etc.
- Review/consider common Frame 6 issues-such as failures of buckets and transition pieces at about 40,000 hours.
- Borescope in advance of planning to ensure more accurate budgeting and scheduling.
- Analyze operating data thoroughly. This is a good benchmark to quantify real improvements made as a result of the outage. Very important to verify if contract terms were met, if upgrades met guarantees, etc.
- Perform tasks in advance of the outage to the extent possible-for example, get parts, expendables, and cribbing onsite and arranged before the outage begins.
- Identify special tooling needed. Precision measuring instruments, turbine support jacks and stands, nozzle pulleys, and the load gear centering ring are some of these.
- Pay special attention to variable inlet guide vanes (IGVs). They have become a big maintenance item. High-flow IGVs should be considered as an upgrade; significant increase in output is likely.
- Write the RFQ (request for quote), making sure to spell out what is included and what is not included.
When was the last time you were at a power/process-industry meeting and listened to a presentation on gear-drive preventive maintenance and repairs? The Frame 6 users were treated to a solid engineering presentation on the subject by one of the leading professionals in the field, Jules DeBaecke Jr, VP engineering at Philadelphia Gear Corp (www.philagear.com), Norristown, Pa.
Gear drives are easy to take for granted. But this would be foolish, because if they fail you don't produce electricity. For gears, a little bit of attention goes a long way. DeBaecke's simple six-step preventive maintenance program:
- Look at trend data, not single data points.
- Be consistent during data acquisition.
- Automate record keeping to enable rapid evaluation of data.
- Run baseline data sets at startup and after repair.
- Identify and maintain access to critical spares.
- Buy only top-quality replacement parts.
Diagnosis of equipment health demands periodic visual inspection as well as analysis of vibration signature, lube oil, and noise and temperature levels. What to look for in your inspection forms the basis for "And finally, don't forget the gears," included in the 2006 OUTAGE HANDBOOK supplement to this issue, p OH-77.
The article also presents a lube-oil system checklist to help you maintain this critical fluid in the top condition required for long gear life.
Accurate evaluation of vibration is important for an accurate assessment of gear condition. DeBaecke cautioned that data are easily misinterpreted. Reasons for this include improper instrumentation, bad choice of data points, variations in operating conditions, and system complexity and/or multiple vibration problems. He added that the choice of data points is critical. Also, that complex systems with multiple data points are difficult to analyze.
DeBaecke suggested that users resist the temptation to be a JV vibration expert. If you identify a problem, he said, call in a professional to interpret the data.
The availability of non-OEM parts is likely to help many owner/operators of GT-based generating facilities weather the competitive storm. But all third-party parts are not created equal; caveat emptor. Before you leap at what appears to be a good deal, it is a good idea to review carefully the engineering and manufacturing processes used to create the parts.
Michel Price, the project manager for nozzles at EthosEnergy Group, Dallas, Tex, helped Frame 6 users better understand the practice of reverse engineering.
Her presentation examined the process of reverse engineering turbine nozzles and buckets-including analyses performed to verify improvements and manufacturing checks made to ensure quality. Five key steps in the process, which takes up to two years to complete, are:
- Review public data.
- Acquire samples.
- Characterize samples (dimensional, visual, functional, material, documentation).
- Create part definition.
- Manufacture parts.
The details of EthosEnergy Group's procedures and tools (engineering and manufacturing) for producing quality third-party components was of high interest.
Many non-OEM parts are simply replicated, Price noted. This is the fastest path to market and if done properly should enable the machine to achieve as-new performance. The most-capable of the non-OEM parts manufacturers often re-engineer or redesign the original component. A goal of re-engineering is to reduce a part's cost by making it easier to produce and/or repair. Redesigns, which are patentable, are done to improve durability/life, performance, cost, and/or repairability.