UPDATE: PowerUsers Combined Conference going digital (CCUG, STUG, GUG, PPCUG)

Covid-19 has wreaked havoc on the CCGT industry’s user conferences and there is no end in sight. PowerUsers, the umbrella organization presiding over six of the industry’s most robust and influential user groups, decided early last week to forego a face-to-face meeting of their Combined Conference this year.

The conference is home to the Combined Cycle, Steam Turbine, Generator, and Powerplant Controls Users Groups. The groups are opting for an all-digital, screen-to-screen series of webinar sessions to disseminate valuable information to owner/operators all over the globe.

Once again, PowerUsers will team up with COMBINED CYCLE Journal to bring this year’s content to your desktop or mobile device, as we have already during the 7F Users Group 2020 Digital Conference, where nearly 600 users are accessing a variety of technical content critical to their operations, both live and on-demand. Presentations, contact information, forum interaction, and interactive Q&A are all at all registrants’ fingertips unlike ever before.

This 2020 Digital Combined Conference will feature many of the same opportunities for vendors to connect with users during this challenging time:

    • OEM and OOEM extended technical presentations.

    • Live special technical presentations.

    • Recorded technical presentations.

    • Virtual vendor fairs with live video feeds (all in one platform).

    • Post-session, deep-dive roundtables.

    • Access to the fastest growing customer demographic: the virtual user group conference attendee.

Details will be emerging in the coming weeks. Email conference coordinator Sheila Vashi, sheila.vashi@sv-events.net, for preliminary updates and to make sure you are a part of all official communications forthcoming. Be safe and see you on-screen.

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7F Digital Conference: Week 4 starts tomorrow, focuses on plant and lube-oil maintenance, engine exhaust systems, rotors, controls

Week Four of the 7F Users Group’s innovative 2020 Digital Conference begins tomorrow at 1 p.m. Eastern with SRP’s Gilbert Shupe presenting on an exhaust-frame strut failure. The Exhaust Session, chaired by Southern Company’s Justin McDonald, has an open discussion period scheduled after Shupe’s presentation.

Two special technical presentations selected by the 7F Steering Committee follow:

Attendees will have access to these speakers after their presentations during an exclusive vendor fair for both suppliers, enabling a deeper dive into specific details of value to their plants.

The fifth and final segment of the Auxiliaries Session, chaired by Bryan Graham of Entergy, starts the Wednesday program at 1 p.m. The feature presentation is on hydrogen purge remote activation by Scott Rose of Perennial Power’s Hermiston Generating Station.

Immediately following Q&A and open discussion on hydrogen purge these special technical presentations will be made:

Attendees will be able to meet virtually with these speakers after their presentations during an exclusive vendor fair for both suppliers.

Sessions continue over the next two weeks (including this week), closing July 16. Registration remains open 24/7 for users only, at no cost. More than 600 owner/operators have registered thus far.

Conference content is compelling and easy to access (presentations posted as videos or pdfs a few days after); plus, no travel required, no additional cost to the plant. Q&A following the presentations is more robust and efficient than at most face-to-face meetings which have “dead” time as microphones are passed around the room and attendees gravitate to email. And don’t forget the perspective gained through use of the live polling system accessible by all attendees.

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Discussion format of rotor session creates a vibrant exchange of experiences

The 7F Steering Committee invigorated last Wednesday’s (Day 7, July 1) program by leading off with a discussion session on rotors rather than a user presentation on the subject, as had been the norm for the other days of the event. The format was simple: A committee member and special user guest greased the skids, so to speak, on the subject of rotor maintenance, and attendees provided a seemingly endless string of questions and experiences. In fact, the discussion leaders had to hit the session trip button so the next speaker, Doosan Turbomachinery Services’ VP Engineering Glenn Turner, could make his presentation.

The two discussion leaders combined have fleet-level maintenance responsibility for more than five dozen 7FAs. They began with a brief introduction of the OEM guidance documents of greatest importance to anyone involved in the rotor-maintenance process—read end-of-life (EOL) inspections and life-extension work. They are GER-3620, “Heavy-Duty Gas Turbine Operating and Maintenance Considerations” and Technical Information Letter 1576-R1, “Gas Turbine Rotor Inspections.”

TIL 1576-R1 refers you to GER-3620 for overall guidance on all centerline maintenance. The latter is now at Rev N (November 2017) which is important for you to have. Don’t have a copy? A simple Google search can provide access. Or, a copy of the presentation may also be helpful and can be accessed on the secure, user-only website of powerusrs.org.

Rotor life limits for the 7FA are 144,000 factored hours or 5000 factored starts, depending on whether your machine is starts- or hours-based. The pages in Rev N of interest to this discussion are 30 to 35, with Fig 45 being particularly important. Reason is that the impact of forced-cooling on rotor inspection calculations is now a consideration, replacing the “trip from load factor” in earlier versions of the GR-3620 document.

Attendees were polled on how they operate their units. More than half (52%) said their machines were hours-based, 16% starts-based. For users with multiple units, 27% said they had a mix of hours- and starts-based machines. Interestingly, only 5% of the attendees said their units had switched from starts-based to hours-based, or vice versa.

Calculation of factored starts can be challenging. There was considerable discussion of what to include in your determination. One of the session leaders illustrated how he calculated the rotor maintenance factor for one unit, which was 1.4 multiplied by actual starts.

The other discussion leader said this was fine, provided the entire rotor has been together for its entire life. If not, track the operating histories of individual components—such as the compressor and turbine if they have been decoupled. This approach likely benefits the owner. GE, it was said, considers the rotor one component.

Other points also were made to illustrate the complexity of factored-hours/starts calculations (particularly the latter). Attendees were urged to do make their calculations as accurate as possible to avoid leaving “life” in the rotor before removing it for an EOL inspection. How would you factor the following into your calculations? 

    • Control system changes.

    • Staff changes.

    • Ownership changes.

    • Upgrades—such as going from 24k hours to 32k on a Dot 04 upgrade.

An idea for extending rotor lifetime surfaced: Shift your high-hours machine to a starts-based unit. No guidance was offered, however.  

It might appear that calculation of the maintenance factor might be a task assigned to the DCS. But that’s not true. A poll showed only 14% of the attendees used the DCS to calculate maintenance factor; 37% said “No” outright. Another 16% said they weren’t sure; double that number track maintenance factor outside of the DCS.

Safety drives rotor EOL inspections. The experts say gas-turbine casings are not designed to withstand a rotor wheel burst, so if that were to happen personnel could be hurt, possibly killed. Rotor disassembly and inspection can mitigate this risk by identifying wheels that should be replaced. The failure of other components, it is said, would cost money and time but likely would not be life-threatening. Cyclic operation is of particular concern because it induces thermal transients and mechanical stresses on the rotor.

Attendees were asked if they were planning on 7F rotor maintenance in the next five years. “Yes,” based on GER-3620 guidance, was checked by 57% of the users participating; “No,” 29%. The remaining 14% said they had to learn more before deciding.

A few takeaways from the conversation included the following:

    • Experience from units hitting the 5000-starts limit: Turbine sections typically are in “pretty rough condition.”

    • The aft end of the compressor gets most wear and tear on cycling units. Think about replacing the 17th and 16th stage wheels at EOL, perhaps even one or more earlier rows. Suggestion was to have a qualified company help you determine if this is a good idea.

    • Expect to replace the first-stage turbine wheel on most starts-based units.

    • Poll: Have you performed a rotor lifetime assessment? “Yes,” 22%; “No,” 78%.

    • One of the nation’s largest utilities reportedly has not yet hit EOL on an hours-based unit.

    • Poll: What are you planning for? Exchange rotor, 29%; lifetime extension, 32%; new rotor, 12%; undecided/do not know, 27%.

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“Little things” can mean a lot, as this case history of a heat-exchanger leak attests

The presentation at the 7F Users Group’s 2020 Digital Conference through Week 3 (two weeks to go) that has generated the most questions and discussion among attendees concerned a leak in a plate-and-frame lube-oil cooler.

Go figure! 

How could a mundane leak generate this much interest at a high-tech meeting? Read on: There are some lessons learned you may benefit from.  

The background: One 7FA at a 2 × 1 combined-cycle cogeneration facility was out of service for an outage. Lube oil to the unit was shut off, but cooling water was still running through the plate-and-frame heat exchanger. This had been standard practice for the last 18 years. During that time plant personnel had performed the periodic heat-exchanger cleaning required without incident.

The problem: Water pushed through the exchanger’s gaskets after the lube-oil system was secured. Water then ran through the exchanger discharge and all associated systems, and contaminated the 6400-gal oil reservoir. By the time the leak was found and the water shut off the reservoir level had risen by more than 3 in., causing oil to flow from the explosion doors. A quick calculation revealed that about 400 gal of water had been added to the oil reservoir, creating a milky mixture in the tank.

Staff considered that after its last cleaning the heat exchanger might not have been tightened to the applicable “crush” specifications for that model and the number of plates it has. The exchanger was disassembled and the gaskets inspected. No damage to gaskets or plates was in evidence, so the lube-oil cooler was cleaned and reassembled. Alfa Laval, the manufacturer, was asked to provide a formula to guide reassembly and assure the proper crush. The total inside spread between the end caps of this unit with 106 plates was calculated at 18.56 in.

Given that proper crush is so important to leak prevention, consider verifying the specs for your exchangers. And when using outside labor for cleaning, share this information with that team; it’s not just a matter of “tightening” a few bolts/nuts after cleaning a plate-and-frame exchanger, as some might think.

Another thought was that the leak began when the lube-oil system was shut down because the oil cooled. The logic: When the oil was hot, expansion prevented leakage of water into the oil side of the unit.

In either case, the takeaway is obvious: Avoid leakage by shutting down the water system before taking the lube-oil system out of service. This lesson learned has been incorporated into plant procedures.

However, a couple of attendees listening to the presentation reported having the reverse occur, with lube oil leaking out when water was “isolated in the compartment.” The fix here was gasket replacement and right-torqueing. This exchange among users, and others like it during the 7F event, was proof that a virtual conference done correctly can be as effective as a conventional meeting for sharing experiences—possibly even better.

Another attendee suggested all gaskets be replaced every couple of years or so because they lose their resiliency. Yet another mentioned baking the gaskets to cure them after cleaning. There was no follow-on discussion related to this suggestion, however.

The presenter said a vacuum truck was brought onsite to remove the oil/water solution in the lube-oil sump. The dregs then were mopped up by hand, the lube-oil filters replaced, and the tank refilled. Entire process took three days. The plant didn’t pursue centrifuging/vacuum dehydration to save the oil because the cogen facility was necessary to support process operations.

A similar situation was reported by another attendee who said the issue at his facility was brittle gaskets in the heat exchanger that failed once the oil pressure was off the unit and cooling water was still in service. It was a mess, he said, with oil spilling out the explosion doors as the speaker had reported earlier.

This tank also was drained and mopped clean before new oil was added. Oil could not be salvaged, the user said. Two days were spent trying to save it before deciding on disposal. Next step was to replace gaskets on all of the plant’s plate-and-frame heat exchangers serving the 7Fs and D11 steamer. All those assets were commissioned around 2000.

The takeaway from this session suggests that if you have Alfa Laval lube-oil coolers installed during the bubble years and have not replaced their gaskets it might be time to consider doing so. A user suggested buying a spare set of plates with gaskets (glued on or clipped on) then swapping them out with the plates in service. Job should take about four hours based on his experience.

Someone else added that when you send plates to Alfa Laval for refurbishment a Zyglo inspection also is performed. It detected a pin hole in one of this user’s plates that allowed oil to enter the cooling-water system. 

The presentation is posted in the conference’s frequently updated presentation library, accessible by users only.

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Dig into the details of products/services available from PSM, Shell/ACT, Doosan

There were two special live technical presentations during Week 3 of the 7F Users Group’s 2020 Digital Conference—one by PSM, the other by Shell/Advanced Chemical Technologies—and one extended live technical presentation from Doosan Turbomachinery Services. The video recordings, available on-demand to owner/operators, bring you up-to-date on the products and services offered by these companies to help keep your plant safe, efficient, and reliable.

The PSM presentation, “What Else Do you Need from your 7F Power Plants,” was divided among Marc Paskin, senior technical lead, combustion and digital; Dr Alex Torkaman, manager, airfoils, upgrades, and rotors; Josh McNally, technical lead, combustion and digital; Tim Hui, manager, combustion and digital; Brian Loucks, technical lead, airfoils, upgrades, and rotors; Dr Greg Vogel, manager, technology programs; Dr Scott Keller, manager, airfoils, upgrades, and rotors; and Ian Summerside, global product manager for F-class and digital.

Technical topics covered during the one-hour seminar were:

    • FlexSuite and FlexRamp upgrades.

    • Gas Turbine Optimization Packages (GTOP™).

    • FlameSheet™ install successes.

    • Total flexibility with FlameTOP™.

    • Proven rotor management solutions.

    • Manufacturing for the future with additive manufacturing.

The Shell/ACT presentation, “Varnish Mitigation—Not a One Size Fits All,” is a collaboration between Chelsea Bukowski (Kovanda), well known to F-class users, and Dr Robert Profilet. Recall that American Chemical Technologies Inc was purchased by Shell in December 2019. ACT and its team continues to operate the ACT business on behalf of Shell for a transitional period.

The video recording covers the following:

    • Introduction to Shell/ACT.

    • Lubricant selection/base stock evolution.

    • Varnish.

    • Mitigation methods for varnish.

    • Top-off fluids.

    • Fluid solutions.

    • Maintenance of turbine oils.

The Doosan Turbomachinery Services presentation by Glenn Turner, VP engineering, will be of particular value to users who have not yet visited the company’s new Houston-area facilities and are not familiar with the company’s products and services for the 7F, including its DART (Doosan Advanced Re-engineered Turbine) program, which is developing new manufacture AGP .04 parts, as well as repairs for these components.

Turner opens with an overview of Doosan’s extensive facilities and engineering and manufacturing capabilities worldwide. He moves quickly through Houston’s shop capabilities—including a 7FA major rotor overhaul. The DART program’s technology upgrades for the 7FA.03 (compressor, combustor, turbine) will be of special interest to owner/operators. Combustion hardware improvements include fuel nozzles and the combustion assembly; plus, the company’s auto-tuning solution. Upgraded designs of buckets, nozzles, and shroud blocks are part of the DART promise to deliver power and efficiency equal to or better than 7FA.04 AGP turbine components.

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Easily connect with and view presentations from key suppliers @ 7FUG 2020, Part II

One of the unique aspects of the 7F Users Group’s 2020 Digital Conference is the opportunity to interact online with the OEM and nearly 50 third-party solutions providers. Ten companies in the latter group were selected by the steering committee to conduct live technical presentations of one or two hours during Weeks Two, Three, and Four of the five-week program ending July 16.

The remaining solutions providers participated in the conference with virtual booths in the Vendor Fair conducted Tuesday and Wednesday of Week One. They connected directly with users via video (or audio) conferencing platforms. They also provided recorded technical presentations for users to access on-demand throughout the year, which can be viewed below.

In case you missed the opportunity to visit with one or more of these companies at the Vendor Fair, the editors provide below brief summaries of the products/services they showcased along with links to that information. The names of experts to contact for details are included.

Suppliers not included in the list below either appeared last week (Allied Power Group, GTC Control Solutions, Nel Hydrogen, Nitto Inc, Parker Hannifin Corp, Dekomte de Temple, Conax Technologies, Donaldson Company, ESC/Spectrum, and Hilco) or will be profiled in CCJ ONsite before our coverage of the 7F meeting concludes on July 20.

Mercer Thompson LLC and IEM Energy Consultants

Ensuring your LTSA is fit for the future

Many owners are rethinking their LTSAs given the proliferation of renewable resources challenging the operation of traditional fired assets. Jason Yost of Mercer Thompson, a frequent speaker at user-group meetings, and IEM Energy Consultants’ Bill Ray and Craig Nicholson, say contracts negotiated years ago may not be calibrated for future needs. The speakers discuss some of the key areas and potential opportunities to consider, plus steps that can be taken to ensure owners are best positioned to effectively negotiate or renegotiate their LTSAs. Takeaways include negotiating strategies, best practices, and how to avoid common and costly pitfalls in the negotiation process.


“Outage in a Box”consumable kit solution for GE Frame 6B/7E/7F engines

Craig Sonnenberg and Jerrod Walters combined for a deep dive into AP+M’s “Outage in a Box®”—one or more containers containing all the consumables required onsite for maintenance outages. The custom, cost-effective packages are delivered directly to the outage site. Walters and Sonnenberg say the company can provide a wide variety of parts from its global network—including engine, package, and BOP parts and components, inlet evap cooling misting nozzles, inlet filters, etc. Services offered include replacements of control, engine-support, and BOP systems.

Braden Filtration LLC

Advancements in nanofiber technology for pulse filters    

If you’ve ever ordered gas-turbine inlet filters, you likely know the name Mcleod Stephens. He’s been serving users for four decades in management positions at three filter manufacturers. But what you may not know is that in the last year Stephens helped to form Braden Filtration LLC, where he is general manager, after purchasing the manufacturing assets from Braden Manufacturing parent Innova Global.

He discusses how the technology of nanofiber manufacturing and application has improved over the years, and how those changes and improvements—targeted at pulse-type air-inlet systems—came about and why. Takeaways for users include the following:

    • How filter life can be impacted positively by new, contemporary nanofiber applications.

    • How flow resistance is reduced.

    • How pulse-cleaning frequency can improve service life.

    • How recent design changes to the media substrates contribute to better performance.

Bureau Veritas

Adjusting turbine-oil monitoring to the current situation

Jorge Alacorn, senior consultant and thought leader on the subject of “Reliability through Oil Conditioning Monitoring and Predictive Analytics” as applied to maintenance, focuses Texas-based Bureau Veritas’ presentation on how to maximize the life of turbine oil by combining appropriate condition tests based on the application, risk of failure, and plant reliability objectives.

He and colleagues Jeremy Erndt and Barry Cato, help owners/operators:

    • Select the correct oil analysis for their plants.

    • Understand the importance of a proper oil analysis.

    • Use oil condition monitoring as a predictive tool to avoid a turbine shutdown.

Services offered by the company include oil condition monitoring, plant lubrication audits, boiler and pressure-vessel inspection, ISO 15001 auditing and training, and leak detection.

Groome Industrial Service Group LLC

AIG tuning and permanent sampling grid

Jeff Bause and Steve Houghton explain how Groome’s turnkey services enable owner/operators to reduce harmful emissions, improve plant performance, and extend the lifetimes of critical equipment. They go on to say the company’s philosophy is simple: Provide quality, innovative services at a reasonable price for its five maintenance service lines—HRSG and refinery maintenance, industrial cleaning and support, surface preparation and coatings, and door and mechanical services.

HRSG maintenance, the service line of greatest interest to 7F users, is supported by strategic alliances with industry experts and catalyst manufacturers to ensure Groome offers the most widely supported and comprehensive turnkey services available in the industry. Specific services include the following:

    • SCR catalyst systems.

    • CO catalyst systems.

    • AIG systems and controls.

    • Retrofit and installation.

    • Boiler tube cleaning.

    • Industrial coatings.

Pioneer Motor Bearing Co

The “care and feeding” of fluid-film bearings

Dr Lyle Branagan, Pioneer Motor Bearing’s engineering manager, is well respected in the electric-power community for his deep knowledge of bearings. Branagan’s 7F presentation focuses on damage mechanisms found in fluid-film bearings for motors, turbines, and generators. Topics including theory of operation, bearing design features and materials of construction, and lubrication basics are reviewed in brief at the beginning of the presentation. This information serves as a backgrounder for the ensuing discussion of some typical damage mechanisms observed in today’s bearings—with an eye toward prevention of recurrence and recovery from the problem.

Branagan’s goal is to give attendees the ability to examine post-service bearings with a better perception as to how markings and damage to the bearing surface would affect continued operation and long-term reliability. Owner/operators will come away with an ability to relate those damage markings to some specific degraded conditions in the machine—such as shaft currents and misalignment.

Pioneer Motor Bearing specializes in the repair and service of large oil-lubricated bearings, with a focus on engineering problem-solving. The company, a license of Siemens Energy, GE, and the UK’s Mitchell Bearings, may be best known to users for its Babbitt-bearing repairs, new manufacture, reverse engineering, upgrades and custom designs, and technical support.

VAW Systems Ltd

Exhaust system retrofit approach

VAW Systems’ core business is the design and manufacture of engineered noise control products for gas turbines, fans, steam vents, and other applications. Dominic Crnkovich and Dennis Seltz introduce owner/operators to the company’s line of silencers, filtration systems, and related components that promise to meet the high performance and quality demands of modern powerplants. The speakers say users can expect high acoustic performance within a relatively small footprint, plus low pressure drop in applications requiring that.

Segments of the presentation likely to be of greatest interest to users is an overview of exhaust-system failures and new challenges, the company’s approach to exhaust-system repair/replacement, and improvements for system longevity. 

National Electric Coil

An improved self-locking amortissuer finger and spring assembly for 7FH2 generator rotors

Bill Harris, NEC’s field services manager for rotating electrical equipment, presents on the importance to generator reliability of the Inconel Spring incorporated into the amortisseur/damper segment of 7FH2 rotors.

The Inconel Spring, he says, is prone to traveling on an axial migration path towards the retaining ring. Migration can lead to blocked cooling passages and the further effects of uneven heating across the rotor. Additionally, if the Inconel Spring makes its way under the retaining ring, damage to retaining-ring insulation can result—possibly even a ground fault.

Harris reviews the mechanisms of spring migration on the rotor components during operation and explains the structure and important function of the rotor’s amortisseur/damping system.

NEC is a company that needs no introduction to most powerplant owner/operators. It specializes in shop and onsite repair and upgrade services for generators and rotating exciters of all makes and models and sizes. NEC also is an experienced winding manufacturer.

Nord-Lock Group

Coupling-bolt issues and solutions with EzFit

Steve Brown, Nord-Lock’s resident expert on expansion bolts, shows how a technology that has proven effective in critical power-generation applications is eliminating the costly, time-consuming challenge presented by seizure-prone fitted coupling bolts during outages. It highlights recent cases that demonstrate the technology’s value in the field. Plus, it offers preemptive steps that plant personnel can take to minimize flange-bolt faults in future maintenance situations.

Brown presents on the downsides and risks of using conventional bolts for turbine/generator coupling and helps users better understand the principles of mechanical expansion bolts—what they are, how they work, and how they mitigate the problems associated with conventional bolts. 

Rochem Technical Services

Compressor cleaning best practices

Following an introduction by Managing Director Martin Howarth, Steve Engelhoff, a familiar face at user meetings in the US, discusses cleaning best practices based on the company’s technical expertise and field experience. Recall that Rochem offers a range of gas-turbine cleaning systems, precision-designed nozzles, and specialist compressor cleaning chemicals to help keep GTs operating a peak efficiency. The company’s Fyrewash products are designed to address all types of fouling and to meet OEM and environmental standards worldwide

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