The 501F and G users groups were the last of the US-based independent gas-turbine organizations serving owner/operators to conduct in-person conferences in 2020. The Vendorama program is normally the first day of the week-long meeting, gave attendees access to live presentations by more than 30 product/services providers offering O&M solutions.
Summaries of most presentations, presented below, testify to the value of the information disseminated. The complete PowerPoints can be reviewed by registered 501F owner/operators on the user group’s website. Non-members who meet the organization’s requirements can gain membership status by completing the online registration form.
Gas-turbine inlet filters: An ongoing maintenance expense or operational investment? How nanofiber technology impacts the filtration marketplace. Braden Filtration
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 a year or so ago 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.
Integrated generator monitoring. Cutsforth
Chris Delavega demonstrated the value of continuous online monitoring for generators. He noted that numerous fault conditions present themselves through unique, repeatable signature patterns in the shaft voltage and ground current of a properly grounded and monitored turbine generator when viewed as a high-speed time domain waveform. Points made by Delavega, and supported with actual charts and data, include the following:
- Brush health analytics data enable personnel to conduct maintenance based on brush condition rather than a calendar basis. This virtually eliminates the risk of having a ring fire because of short brushes.
- Shaft ground monitoring allows early indication of problems such as shaft rubbing, brush sparking, shorted stator laminations, isophase neutral faults, inter-turn shorts in rotor windings, etc.
- Electromagnetic interference (EMI) monitoring looks for patterns/signatures in the RF spectrum from 30 kHz to 100MHz to find arcing, corona, partial discharge, noise, sparking, etc.
Gas-turbine power augmentation by wet compression. Mee Industries Inc
Thomas Mee may be the industry’s foremost expert on fogging/wet compression, having decades of analytical and plant-level experience on the technology. He encouraged attendees to consider this cost-effective method of power augmentation for delivering additional megawatts virtually instantly in times of need.
Fogging/wet compression systems are easy to integrate with gas-turbine controls, he said, adding that his company typically can deliver the necessary equipment in 12 weeks or less and can connect the new system to existing equipment within a favorable outage window—perhaps in only 24 hours.
Erosion risk is reduced with small droplet size—a distinguishing characteristic of Mee systems. Droplet size and its impact on equipment received significant air time.
Advanced single-layer turbine warming system. ARNOLD Group
Pierre Ansmann opened his presentation on “the most advanced turbine insulation combined with a high-performance heating system to improve startup flexibility,” by summarizing its value proposition thusly:
- Increased in-market availability.
- Lower startup costs.
- Reduced thermal fatigue and longer mean time to repair for critical components.
- Increased operating flexibility.
He reviewed alternative warming-system arrangements, rejecting those integrating the heating circuits in insulation blankets, installing the heater on a thin mattress below the blanket, and using gas-fiber-insulated heating cable. The optimal system for the upper casing, they said, is heater on metal mesh baffle, for the lower casing, permanent mounting of heating cable below the split line.
The ARNOLD system features interlocking high-performance blankets which conform perfectly to the turbine surface. High-quality materials and manufacturing, and long-term high-temperature resistance, allow the company to guarantee reuse of its insulation system for 15 outages without a decrease in efficiency.
More than five-dozen thermocouples, strategically located on the turbine, ensure proper heating. Each of the 18 or so heating zones has t/cs installed on the heating wires to double check if the zone is responding correctly and at the specified temperature. Below every heating zone, multiple t/cs are mounted on the casing to confirm even heating of the turbine.
Ansmann said the ARNOLD warming system can maintain your turbine in a hot-start condition for at least four or five days after shutdown. No preheating of the turbine is required prior to a start within this time period, reducing startup fuel consumption and auxiliary power.
Think beyond the catalyst to improve your plant’s performance. CECO Peerless
The company’s ammonia injection grid (AIG) is designed and optimized to provide the desired reagent distribution across the duct to assure expected SCR efficiency and performance. The square cross section of CECO Peerless’ EDGE™ AIG lances are said to promote better mixing, thereby improving NOx reduction, reducing ammonia slip, promoting longer catalyst life, and reducing the cost of operation.
A laboratory comparison of EDGE and an AIG with traditional lances revealed better performance from the former in half the distance from the AIG grid to the catalyst. A 30% reduction in ammonia consumption was reported by a plant after conversion of its AIG to EDGE. Brief case studies also are included in the presentation.
Is your SCR/CO system ready for turndown? How increased NO2/NOx ratios require additional SCR performance. Environex Inc
Andy Toback regularly shares Environex Inc’s knowledge of CO and NOx control technologies with CCJ readers. You can access some of this information with a keyword search of the magazine’s archives at www.ccj-online.com. At the 501F Users Group’s 2020 Vendorama he began with the following observations:
- NOx consists of two measured pollutants, NO and NO2.
- NO2/NOx ratios above 50% identify with a significant decrease in SCR performance—that is, NOx conversion.
- High levels of NO2 are found at turndown conditions.
- CO catalyst can increase the NO2/NOx ratio.
- Turndown lowers HRSG temperature which reduces SCR performance.
A case history presented revealed the installed catalyst did not have sufficient activity for the elevated NO2 condition experienced. Adding additional catalyst would increase the pressure drop by 0.6 in. H2O. Suggestions to users: Instrument to monitor NO and NO2 separately; enlist a stack tester to measure low-load NO2/NOx ratio.
Turbine retrofit acoustical and structural design and installation overview. Durr Universal
Acoustical and structural engineers walked attendees through a couple of 501F silencer retrofit projects that provided valuable insights for anyone considering same. This presentation required back-to-back sessions, so it was twice the length of others made during Vendorama, totaling more than 60 slides. While it reviews the basic fundamentals of acoustics and aerodynamics required to follow the slides, having background knowledge of these subjects would be very helpful in getting the most from the presentation
Generator maintenance testing and inspection. National Electric Coil and Advanced Turbine Support LLC
NEC’s Howard Moudy and Rod Shidler of Advanced Turbine Support collaborated on this presentation. Motivation for the partnership was to provide increased insight into generator condition in less time and at lower cost than was possible previously. When the partnership’s equipment for stator wedge tapping and stator core EL CID testing are coupled with other inspection and testing tools, a solid machine assessment is possible, said Moudy and Shidler.
The presentation has several tables listing inspection and testing activities, their purpose, and frequency—a handy checklist for maintenance personnel. Tables are the following;
- Visual inspection of stator winding, stator core, and rotor.
- Rotor electrical tests, including insulation resistance, winding resistance, flux probe, and pole balance.
- Stator electrical tests, including insulation resistance, winding resistance, hi-pot, and DC ramp.
- Specialty stator tests, including EL CID, core loop, wedge tightness, partial discharge, and bump test.
Ovation machinery health monitoring solutions. Emerson
Jason King, machinery health solutions manager, discusses how turbomachinery protection and condition monitoring can be accomplished on the same platform as the turbine controls, providing automated diagnostics to operators without requiring them to learn vibration analysis. For vibration analysts, onsite or at a remote diagnostics center, full-featured analysis capability is possible while still meeting cybersecurity requirements.
Liquid fuel reliability: The good, the bad, and the unexpected. JASC
Schuyler McElrath, one of the electric-power industry’s leading experts on liquid fuel systems for gas turbines, has new product development as one of his responsibilities at JASC Controls. His presentation simplifies the complexity inherent in liquid fuel systems and focuses on what design features owner/operators should be aware of to assure reliable starts on oil, reliable transfers from gas to oil, and vice versa, and reliable operation on both fuels. McElrath stresses that while some issues can be addressed with hardware upgrades, system infrastructure changes are an equally important part of the performance improvement process.
Hydraulic filter-element multi-pass tests. Hy-Pro Filtration
Richard Trent walked attendees through multi-pass testing of hydraulic filter elements for dirt holding capacity and beta ratio. The test is intended to measure hydraulic (lube) filter performance in a controlled laboratory setting. There are several versions of the test, some closer to the “real world” than others. The details:
- ISO16889 Multi-Pass, steady-state flow.
- ISO/CD23369 Cyclic Flow, cyclic flow.
- SAE ARP4205, cyclic flow.
- Dynamic filter efficiency (DFE), dynamic flow (cyclic).
A point to keep in mind: All filters shed particles during flow transitions. In the real world, flows change, often rapidly. Thus, filters with better cyclic-flow particle retention provide better equipment protection.
Trent reviews the advantages and disadvantages for each of the four tests with helpful illustrations.
501F exhaust cracking RCA and expansion joint upgrades. Frenzelit
If your expansion joint is suffering a soft-goods failure and/or exhaust-frame cracking is an issue you’re dealing with, this presentation is worth reviewing for its many photos of failures and repairs.
Common root-cause failures of expansion-joint soft goods are the following:
- Missing internal insulation at the round-to-square transition behind the vertical cover plate.
- Evidence of insulation breakdown attributed to water saturation is the discoloration and hardening of the downstream insulation.
- Common root causes of frame cracking are these:
- Sagging of external insulation, thereby exposing the bottom area of the joints and frame components to heat capable of causing expansion-joint failure as well as radial and lateral frame cracking.
- Sagging external insulation and missing internal insulation are conducive to superheating of the bottom of the frame, causing non-uniform heating of structural components with frame cracking the result.
Selecting the correct lubricant. American Chemical Technologies (Recall that ACT was purchased by Shell in late 2019, shortly after this presentation was developed for the 2020 meeting of the 501F Users Group.)
Chelsea Bukowski (née Kovanda) presented a primer on lubricant selection of practical value to O&M personnel new to the industry as well as to experienced staff requiring a refresher. Lubricant selection is one of those subjects you might not think about for years but when necessary it’s good to have a backgrounder like this at your fingertips. Topics covered were the following:
- Functions of a lubricant.
- Overview of base stocks (Groups I through V).
- The three types of finished lubricants (rust and oxidation inhibited, anti-wear, and extreme pressure or EP formulations).
- Selecting the optimal lubricant for the two most common powerplant applications: electrohydraulic control (EHC) systems and turbine lube oil.
This is a presentation that could provide the basis for a lunch-and-learn session in the plant break room. It covers the compatibility of new and existing lubricants, additives, viscometrics (measures of viscosity, viscosity index, and pour point), safety (flash point and toxicity), oxidation and hydrolytic stability, fire resistance, and environmental impact.
Bukowski spent most of her time at the front of the room addressing the value of polyalkylene glycol (PAG) as the fluid of choice for EHC and lube-oil systems. Recall that PAG is a Group V base stock—man-made. Powerplant experience is highlighted as well as PAG’s value as a treatment for varnished systems.
De-mystifying varnish analysis: remedies and benefits. C C Jensen
Technical Manager Axel Wegner presented on the following three methods to remove varnish:
- Physical filtration, including absorption and adsorption. In use are depth or surface filters with and without preconditioning: electrostatic and balanced-charge agglomeration.
- Chemical filtration. In use are cartridges with chemical bead compositions of varying mixtures that can be adjusted to accommodate different brands of lube oil and machine types.
- Depth-filter absorption/adsorption with advanced agglomeration, called VRU in C C Jensen speak. These systems precondition the oil in a way that all soft contaminants fall out of solution, agglomerate, and are removed by depth-filter inserts with high dirt-holding capacity.
Wegner answered the question, “Which of these methods should you use to remove varnish?” this way: It depends... on the efficiency of the system in different applications. More specifically:
Systems operating at oil temperatures of around 100F and below can be treated with any of the methods identified above; many brands are available.
Systems operating at oil temperatures above 100F are more difficult to be treated as solubility and varnish formation increase.
Another factor affecting varnish removal, he said, is run time versus downtime. As oil cools and the filter remains in service, it will collect anything coming out of solution.
Lessons from the Australian coast: Applying the three-pillars-of-filtration performance. Donaldson Gas Turbine Systems
Mike Roesner presented a case history illustrating the value of his company’s Three Pillars methodology for selecting the optimal filtration solution at a given site—in Australia in this case. The advantages cited were longer filter life, more stable output, additional equipment protection, and lower cost of ownership. Side-by-side testing of sister units (one with the new filters, the other with the originals) was conducted to verify results.
Improving SCR performance on gas-fired units. SVI Dynamics
Stringent regulations on NOx, CO, and ammonia slip are dictating the need for highly efficient SCR systems. Although CO and SCR catalyst designs are advancing to meet these new regulations, SCR system designs are not always equipped to manage the performance requirement improvements.
Industry veteran Bill Gretta, SVI Dynamics’ SCR product-line director, understands. His company, he says, has incorporated years of knowledge and experience gained from work on SCRs manufactured by all of the major vendors into SVI’s new ammonia injection grid. If new is not optimal, SVI can provide in-depth analysis of your emissions control system to suggest enhancements that will improve reliability and efficiency.
Part of Gretta’s presentation illustrates the benefits of CFD modeling in guiding performance upgrades. He also explains how SVI would conduct a design review of your system and how to develop a PM inspection plan for your SCR.
Inlet and exhaust life extension. Schock Manufacturing
Schock Manufacturing, which specializes in retrofit solutions for auxiliaries at the gas-turbine inlet and exhaust, identified typical inlet systemic problems, issues in the 501F exhaust section, and the simplicity of proper routine repairs. The presentation contained about four-dozen photos to assist users in identifying problems they should be aware of. Attendees then were invited to book a free inspection on the company’s website.
Unconventional design/construction leads to complex stator rewinds. AGT Services Inc
Jamie Clark’s well received 60-plus slide presentation with photos of high value for helping O&M personnel come up to speed regarding the key steps in a stator rewind was the subject of an article in CCJ No. 63, p 48.
NAES and Duke case study TrimKit. Millennium Power Services
Valve issues have become a headline item at user-group meetings in the last couple of years given the wear and tear being experienced by severe-service valves serving steam turbines and HRSGs in cyclic operation. This presentation is recommended reading (by the editors) for owner/operators having to buy parts—such as stems, plugs, cages, seat rings, soft goods, etc—and restore flow-control devices to perform their intended functions. It provides case histories that compare the cost of parts, lead times, and refurbishing options from the original manufacturer with those for third-party suppliers.
The speaker points to these pre-outage savings:
- Reduction in inventory management cost.
- Elimination of pre-outage ordering by the user, the burden being moved to the supplier.
- Many part numbers replaced by one “kit” number.
- The outage savings including the following:
- A 50% reduction in labor verses open and inspect.
- Outage easier for the owner/operator to plan and bid.
- No surprises with missing parts or searching the warehouse for individual parts.
The saving possible from using pre-owned parts instead of new parts was also reviewed.
Mission-critical fire protection. ORR Protection Systems
Fire protection is a topic in safety discussions at virtually every user group meeting, one that seems to be generating more interest as plants age. For example, systems installed 20 or more years ago have been cited for unwanted release of the extinguishing agent because of unreliable sensors. In some cases, the extinguishing agent is no longer in favor and should be replaced.
It’s important to keep safety systems current and well maintained. With the many retirements and staff changes of late, perhaps the person with most knowledge of your plant’s fire protection system is gone. That knowledge gap must be filled. This presentation is a good first step in the learning process. It offers a reference list of fire-protection codes and standards with which you should be familiar.
Orr promotes itself as a one-stop shop for things having to do with fire protection—including alarm, detection, notification, and suppression. It provides testing, inspection, and maintenance services for all types of fire protection systems offered by the major manufacturers of that equipment. This presentation focuses on CO2 and water-mist systems.
The 10 most frequently asked questions about gas-turbine compressor cleaning. Rochem Technical Services
This presentation seems well-suited for guiding a discussion session on compressor cleaning in the break room over a pizza at lunchtime. The questions asked and answered are the following:
- What are the options when cleaning a gas turbine?
- Why clean the compressor?
- What are the benefits of cleaning?
- Water versus chemical cleaners—what’s more effective?
- Where should you place the compressor cleaning nozzles?
- What if the foulant redeposits in later stages?
- What about erosion as a result of compressor washing?
- What are the effects of surface wetting?
- Is there a need to heat the wash fluid?
- If HEPA filters are installed is a compressor cleaning system still necessary?
- Fluid-film bearing visualization. Pioneer Motor Bearing Co
Pioneer Motor Bearing’s 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.
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 licensee 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.
501FUG: 2020 Conference Review
501FUG: Presentations by Owner/Operators
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501FUG: Special Closed Sessions – GE
501FUG: Special Closed Sessions – Mitsubishi Power Americas
501FUG: Special Closed Sessions – PSM
501FUG: Special Closed Sessions – Siemens Energy
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