Originally published in CCJ ONsite | The pending retirements of generating-plant personnel, discussed at virtually every industry meeting for at least the last five years, are finally happening. Look at the participants in the next user group meeting you attend. You’ll see that the sea of white hair of the recent past is now speckled with black, brown, and blonde, and the overwhelmingly American white male audience is transitioning to one that includes meaningful participation by women, other races, and many nationalities. In effect, your industry is becoming melting pot for talented engineers and technicians from around the globe.
No doubt that the loss of experienced deck-plates personnel has left a significant void in O&M knowledge at some locations. Despite the warnings and endless rhetoric, little was done by most owner/operators to capture the know-how of veterans before they walked out the door. And with the military shrinking, the seemingly bottomless pool of talented navy vets is rapidly evaporating.
Grassroots skills development is necessary. Stop-gap measures are required to meet today’s obligations in some places. These include on-the-job and in-house training, and attendance at user group meetings to grow staff knowledge on the specific gas turbines installed in your plant. Long-term, foundational education in generation technology and equipment is required to develop a workforce capable of operating the new high-tech gas turbines using sophisticated electronic tools and diagnostics.
Regarding in-house training, some companies and plants have made more progress than others. Consider, for example, the skills-development programs at Effingham County Power and PSEG Fossil LLC that have been recognized with CCJ Best Practices Awards. Several institutions, with industry support, recently have started two-year programs to develop multi-skilled technicians for power and process plants. These include the Fort Myers Institute of Technology, Oklahoma State University Institute of Technology, and Idaho State University’s Energy Systems Technology & Education Center.
To provide the best candidates for these higher-education programs, industry leaders such as Dr Robert Mayfield, an F-class plant manager, are promoting STEM (Science, Technology, Engineering, and Mathematics) and CTE (Career and Technical Education) programs in elementary, middle, and high schools. Mayfield recently completed his three-year term as chairman of the Virginia governor’s Career and Technical Education Advisory Committee.
The independent users groups managed by all-volunteer steering committees employed by owner/operators are providing the industry a valuable service by keeping the plants “connected” by sharing information in face-to-face meetings and through online forums. CTOTF™ differs from the typical user group, which focuses on a particular engine type—7F, 7EA, 501F, 501G, etc.—in that it covers most all makes and models of gas turbines and ancillary equipment as well.
A unique feature of each CTOTF meeting is a half-day CT-Tech™ workshop, designed to address some of the plant-level training needs of the rapidly evolving industry. This session, the brain child of the organization’s proactive leadership committee, provides expanded instruction and training in plant operations and design theory on user-identified subjects at no additional cost to registered attendees.
“Fundamentals of Combined Cycle O&M” was the title of the “course” presented at the spring 2015 meeting by William Lovejoy, PE, director of engineering for NAES Corp. He has 31 years of experience in doing just about everything related to power plant design, operation, maintenance, and management—mechanical, electrical, and I&C. In his day job, Lovejoy is the primary technical resource for nearly a hundred power plants representing over 300 individual generators and prime movers.
Lovejoy presented for about an hour on each of the three topics listed below and led discussions in each of those areas to be sure attendees had their questions answered.
Electrical basics.
Air side of HRSGs.
Steam/water side of HRSGs.
The electrical portion of the workshop focused inspection of isophase duct maintenance, generator stator protection, operation of metal-clad switchgear, and valve-regulated lead/acid batteries (VRLA).
Isophase duct. He recommended annual inspections of isophase duct and using an engineering drawing and photos showed where to look for problems. Expansion joints are prone to cracking on cycling units, he said, because they typically are designed for 1000 cycles. It doesn’t take long to get there on a daily-start unit. Also, verify that drains are clear because water will accumulate over time and freeze in winter. Lovejoy said that if you inadvertently ground isophase bus in a second spot you’ll burn off the paint. Infrared thermography under load also will identify a second ground.
Generator stator protection. Lovejoy suggested that everyone review their generator protection schemes to verify 100% stator ground protection. Historically, he said, full protection was not believed necessary by some designers because damage required two faults and the likelihood of occurrence was low. However, recent losses have at least some of the naysayers thinking otherwise. Given that technology has reduced significantly the cost of 100% stator coverage, it’s prudent to increase the level of protection.
Metal-clad switchgear operation. A recent arc-flash event occurred when a 13.8-kV breaker was racked in while closed. Part of the incident focused on the indication of breaker position. The breaker was closed and the physical evidence proved it was closed, but everyone involved saw an “open” indication. Suggestion was for plant management to review breaker operating procedures with all employees qualified to operate this equipment and to identify alternative methods for determining breaker position independent of indication flags.
VRLA batteries have been known to self-destruct when placed under sudden high load. They will fail in an open-circuit condition and not supply power to the emergency loads. In many power plants, the DC battery banks provide emergency power to the backup lube-oil pumps—a sudden high load. In one instance involving VRLA batteries, lube oil was not supplied to the steam turbine and all bearings were damaged. A risk analysis seems prudent for those relying on VRLA batteries.
HRSGs. Lovejoy spent quality time discussing HRSG cleanliness and the appropriate time for cleaning finned tubes. The analysis was an economic one. He pointed out that for a 7FA, an increase of 3 in. H2O in backpressure reduces output by about 1 MW and increases heat rate by 15 Btu/kWh.
The impact of backpressure on firing curves was his next discussion point followed by long-term performance tracking. The latter showed by way of plotted data what could be expected in terms of recoverable degradation. Lovejoy’s two-dozen slides on the importance of drum level and how to assure accuracy in its measurement presented information that most in the room probably had not seen previously. You can access this information in the CTOTF Presentation Library.
Discussion of desuperheater and high-energy piping issues covered much of the same territory as this speaker and others had presented before CTOTF attendees.