Western Turbine’s special technical presentations

Posted on July 5, 2017 by Team CCJ

Western Turbine Users Inc increased by 50% the number of speakers participating in the organization’s popular special technical presentation sessions at the 2016 meeting to expose attendees to more subjects of interest beyond the basic engine. The new agenda was well received and nine presentations also were scheduled for the 2017 conference in Las Vegas.

The March 21 program at the South Point Hotel & Spa began at 2:30. Three one-hour sessions were conducted in series, each offering three concurrent presentations. The titles of the presentations in the lineup below are linked to abstracts prepared by the editors. Registered users wanting to dig deeper can access the actual PowerPoints at www.wtui.com.

Session 1.

Session 2.

Session 3.

The value of checklists in troubleshooting

Gundershaug spoke to the value of checklists in troubleshooting. He introduced the subject by stressing the need to make plant processes systematic to keep things from falling “through the cracks.” Without systematic processes, he said, “we are vulnerable to:

      • Processes left to chance;

      • Processes left to human error;

      • Sometimes we do it, sometimes we don’t.”

The Calpine plant manager admitted to being “obsessive about the use of checklists,” because he believes nearly all processes can be improved by using them. “I feel that often we get bogged down developing robust and complex procedures to establish the ‘why’ and ‘how’ of processes, yet often missing in the implementation is the tool to make it happen and the process for determining that it is being done correctly.”

Have a plan. Just as it is important to use a procedure when you start a powerplant, Gundershaug said, it is important to have a structure for troubleshooting complex issues. It will ensure consistent positive results and improve the outcome. A friend, Nick Voorhis, was credited for the following troubleshooting methodology that Gundershaug embraces:

      • Determine the problem. Site personnel can get caught up in working on the symptom of an issue and not the problem itself. Important to discuss the problem with all stakeholders, to weed out opinions, and to concentrate on the facts.

      • Gather information. The more information you have available for reference, the speaker said, the more likely the issue will be resolved. He suggested reviewing the documentation, witnessing the problem personally, and determining if the problem is intermittent. Also, if software logic is involved, be sure you have access to understand the process.

      • Form a hypothesis. It is important, Gundershaug continued, for plant personnel to use the information gathered to derive a hypothesis; it supports a learning culture. Tools at your disposal include OEM flow charts, test data, measurements, etc.

      • Test the hypothesis. After deriving the hypothesis, develop a way to test the theory. This is fundamental to the process because it requires those involved to become experts on the issue.

      • Implement the repair. Focus on repairing the component determined to be the root cause of the problem. Afterward, determine if the repair was successful. Also verify that the repair has not created a new issue.

      • Analyze the results. You may find test results challenge investigators’ assumptions and hypothesis. If this is so, ask these questions: Was the hypothesis correct? Is more testing required? Is a new hypothesis needed? If need be, continue or return to previous steps in the process.

      • Document the results. According to Gundershaug, this may be the most important step in the process. Documentation helps to form and reinforce long-term memory, he said, and becomes a tool for analyzing future events. The value of documentation extends to the following:

        • It is a repository of information that can be shared among plant personnel to increase knowledge and awareness of the issue.

        • Enables the sharing of information outside the immediate work group to promote knowledge across the fleet.

        • An RCA will expose other issues and aspects of the problem that were unknown in the early phases of troubleshooting.

Gundershaug stressed that “you cannot fix something that you do not understand” and went on to illustrate use of the troubleshooting checklist for diagnosing and correcting an LP turbine overspeed issue and an engine trip caused by what plant instrumentation said was a vibration problem. 

Fire protection

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. The presentation by Chuck Hatfield of Orr Fire Protection Systems is a good first step in the learning process.

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. The company also offers design/build, system modification, and decommissioning services, focusing on businesses with mission-critical operations—like powerplants.

Hatfield’s presentation addressed CO2 and water-mist systems. Given the number of slides and the amount of material covered, this could have been divided into two presentations. No matter, registered users can access the slides at www.wtui.com; they are easy to follow.

The basis for Hatfield’s CO2 system coverage was NFPA 12, “Standard on Carbon Dioxide Extinguishing Systems.” He referenced the 2005 standard but be aware that the latest version was published in 2015. CO2 is an effective suppression agent, but there are safety concerns for personnel.

Hatfield discussed normally occupied, normally unoccupied (but occupiable), and unoccupiable areas, and things of general importance regarding CO2 systems—such as safety-sign specs (type size, color, etc) and where they should be placed, supervision of automatic systems and manual lock-out valves, rules for discharge pressure switches and pneumatic time delays, provisions for prohibiting entry into given spaces, etc.

Locations where new CO2 systems should not be installed was another topic. The standard says, “Carbon dioxide total flood systems shall not be used in normally occupied enclosures if other fire extinguishing agents can be used to provide an equivalent level of fire protection to CO2.”

You hear more about high-pressure water mist systems today than only a few years ago because of concerns about the accidental release of CO2 when personnel are in normally unoccupied spaces—such as the gas-turbine compartment. In fact, at least one OEM prohibits package entry when the GT is in operation.

Hatfield went on to describe high-pressure water mist systems, importance of droplet size, etc. Most of this should have been familiar to LM owner/operators because virtually the same technology is used in GT inlet systems to restore power lost on hot days.

What appeared helpful to many in the room was the speaker’s rundown on the offerings of four major suppliers: Marioff Co’s Hi-Fog®, Fike Corp’s DuraQuench™, Securiplex, and Victaulic Co’s Vortex™. He covered design details for each.

For some attendees, the last was the most interesting system given its use of a supersonic emitter to create a multi-layer shock wave of nitrogen which atomizes the water to a sub10-micron mist. It creates a homogeneous suspension of nitrogen gas and water.

Aero GT controls

Woodward’s Eric Freitag and John Stulp picked up in Las Vegas where colleague Mike Toll left off last year in Palm Springs. They began “Aero GT Controls 102” with a review of Toll’s “Aero GT Controls 101,” hitting the highlights of control-system architecture, presenting an overview of the engine system and critical sensors for speed, pressure, temperature, etc, and reviewing basic control theory.

Then they conducted a series of what they referred to as “lab exercises”:

      • Turbine startup (light-off and acceleration to synch idle).

      • Ramping to maximum power.

      • Sprint™ operation.

There was a quiz after each exercise and a final exam.

Certainly was an interesting presentation approach, one conducive to learning. It held audience interest and encouraged questions and discussion.  

Borescope findings, critical service bulletins

Reed Services Inc’s Dale Reed was on the Tuesday afternoon program for the third year running. He’s popular among LM6000 owner/operators judging from the full meeting room year after year. Reed’s primary reference for this year’s presentation was the same one he introduced to the group in 2015: GEK 105059, Volume 1/Chapter 12 (in particular Table 12-1).

The speaker’s focus was on borescope inspections, which are recommended as part of the maintenance overhaul for the LM6000PC every 4000 hours, 450 starts, or annually (whichever comes first).  

Reed focused on Service Bulletin (SB) 310 first (later SB 283), showing and explaining what users should be looking for during borescope examinations and the results they don’t want to see. He then explained to attendees how to extract information from the document to determine if a particular service bulletin is critical to their operation.

The cover page provides the following information:

      • Subject—the system or part that is affected.

      • Category—optional, routine, campaign, alert.

Planning information is included in paragraph “I.” It drills down into the product, model, serial numbers affected, the reason for the service bulletin, general description of the action required, tooling and parts requirements, man-hours it should take to complete the tasks recommended, etc.

Reed said the most important information for determining if a particular service bulletin is critical to your operation is found in paragraph “I,” sub-paragraph D—compliance. It tells you if compliance is optional (financial or operational benefits), routine (will improve operating characteristics, reduce lifecycle cost, etc), campaign (enhance product reliability), or alert (immediate action required).

Sub-paragraph D also describes the level of expertise required to complete the recommended actions—that is, can the work be done in the field by trained maintenance personnel or must it be conducted offsite at a service or repair center? The timing of remedial action is also found in this section. Examples: Prior to restart of the engine, at first opportunity, at next depot visit, etc.

Paragraph II provides detailed instructions and diagrams to complete the work recommended, paragraph III where to register your compliance record (GE portal, e-mail, fax, etc).

Battery maintenance

Sam Ayoubi of Borri Power US Inc had a PowerPoint with far too much information for a 50-min presentation; the company’s history and extensive product line alone took a dozen slides.

However, this is a presentation owner/operators might want a copy of because it could be used  as a core component of an in-house training program.

Here’s a sample of the content:

      • IEEE and NERC standards that apply to battery maintenance.

      • Maintenance/inspection schedules (monthly through five years) recommended for all types of batteries—including when to (1) conduct visual inspections, (2) check float voltage, specific-gravity, and connection resistance, (3) take temperature readings, conduct tests, and check safety equipment.

A separate section of the presentation focused on chargers and included a comparison of the various charger technologies (ferroresonant, mag amp, switch mode, and SCR), digital displays, standard features, alarms, and options, etc.

Partial-discharge testing

A primer on partial discharge—small electrical sparks that occur at voids (air pockets) within, or on the surface of, insulation and degrade it—was conducted by Iris Power’s Sunny Gaidhu. His objective was to help users monitor the condition of their stator-winding insulation via regular online PD testing. If identified early enough, insulation damage might possibly be repaired. If ignored, there’s a high risk of stator-winding failure, the speaker said.

Gaidhu’s slides, like Ayoubi’s (immediately above) might complement other material selected for an in-house training program. To dig deeper on this subject, conduct a keyword search on the CCJ website at the top right of the page. There are several articles posted that can add to your staff’s collective knowledge—including one by the highly regarded generator troubleshooter, Clyde V Maughan, president of Maughan Generator Consultants.

Aero generator O&M

Derek King, who recently founded Mega-Watt Consulting LLC, is well known to many LM owner/operators, having served as the head of the Brush aftermarket services unit in the US for many years. Brush generators are widely used in GE aero packages.

King is challenged as a speaker with a time limit because he literally knows too much and wants to share everything he’s learned over the years (decades). His 66 slides were the foundation for a productive half-day (or longer) workshop.

King began at the beginning: His third slide discussed an 1880 lighting dynamo and distribution system in New York City. This is not a criticism; CCJ also has material going back that far in its offices. We’re both information junkies.

King then dived right into generator basics—how electricity is produced, how losses are minimized, etc. Next topics were rotor and stator construction. He then transitioned to maintenance, spare-parts you should have on the shelf, upgrades, generator monitoring, rotor ground-fault detection, bearing examination and replacement, how to remove and ship the rotor, stator inspection and what to look for, rewind, damage mechanisms, etc.

This seems like an excellent presentation to review before performing maintenance on a generator that requires removal of the field. You can learn a lot about what to look for, and where to look, from the photos.

HRSGs

Ned Congdon, PE, of HRST Inc’s West Coast team, has been a “regular” Tuesday afternoon presenter for several years. At each meeting he addresses a different element of heat-recovery steam generators; put them together you have an aero HRSG handbook. Congdon’s focus in 2017 was evaporators—for natural-circulation boilers and once-through steam generators.

In case you’re unaware, HRST does not manufacture boilers but its staff inspects, audits operations, supervises maintenance, re-engineers components not meeting expectations, and troubleshoots HRSGs worldwide made by virtually all manufacturers.

Congdon’s was another of the 2017 meeting’s “keeper” presentations—an editorial opinion. He offered a good mixture of engineering (beginning with what’s the function of an evaporator and how it works) and practical O&M. Congdon shared a wealth of meaningful photos from HRST’s extensive files to illustrate problems (like flow-accelerated corrosion, under-deposit corrosion, etc) and explain why they occurred and how to avoid them.

The boiler expert touched on chemistry and gave cycling effects on evaporators and drum downcomer nozzles their due. Common errors related to installation of steam separators and drum gaskets offered valuable lessons.

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