Editors in the field: Notes from plant visits, user discussions in 1Q/2015

Combined cycles will run more when the true costs of cycling coal plants are factored in. One owner’s engineer said some people are not being “honest” about coal-plant startup and cycling costs based on analyses his company has conducted.

Frame 7s. One user confided that his engines cycle “all over the place.” In peak season, the units may operate base-load; at other times they may start and go to minimum load for an hour or so and then shut down. Intervals between combustion inspections have been reduced to 450 starts to match fallout experience. Concluding remark was that Frame 7s are “tough machines.”

More wind capacity than coal is likely a few years down the road, an employee of a Midwestern utility told the editors. But not everyone in the company is comfortable with this prospect, he continued. In fact, the plan to retire upwards of 1000 MW of coal capacity this year has been moved forward because of system reliability concerns.

New peaking capability versus upgrade of existing assets was the topic of one conversation. A user mentioned his company had investigated the purchase of a few LMS100s to cope with the idiosyncrasies of large wind penetrations in its service area, but passed on the opportunity in favor of reconditioning old peakers. Catching up on deferred maintenance for less than the cost of one LMS100 restored confidence in more than 750 MW of mature simple-cycle engines in the company’s portfolio.

Improvements in wind turbines likely will cause more challenges for GT fleet owner/operators going forward. The latest models are able to harvest more of the wind’s energy and raise the capacity factor of these assets; the new machines can withstand wind speeds of up to about 60 mph, according to the user interviewed.

Ouch! Some GT mods in one power producer’s long-term plan are getting a second look. The user speaking with the editors said OEM bids are “out of the ballpark.” He added that the dollars budgeted for maintaining the availability and reliability of existing GTs over the next three years was low compared to bids received.

Predictive analytics for GTs. One owner/operator mentioned it was not actively pursuing predictive analytics for the company’s gas turbines—but perhaps it would when control systems are upgraded. The user did offer that analytics are helping on the generator’s coal-fired units.

During another discussion on analytics, a plant O&M manager offered that, in his opinion, Cycle Watch wasn’t “doing the job” in providing predictive intelligence for GT start-ups, mirroring the experience of at least a few others. However, he said, his plant has gotten benefit from the GE SmartSignal® “Shield” product. The software-based remote monitoring service was said to have averted trips from gas inlet temperature stemming from issues with fuel gas heaters. Confirming what several others have said at user-group meetings, such as CTOTF™, predictive analytics software continues to identify “lots of instrumentation issues.” In fact, more than 50% of the so-called “catches” are associated with instrumentation.

Frustration was the feeling conveyed by one user who said his plant has experienced a “terrific number of technical problems” with its 501FD2 gas turbine/generators since commercial start about 10 years ago. He had the impression that his engines were seeing certain problems earlier than others in the fleet, but didn’t elaborate. The Aeropac generator took the brunt of his criticism. This machine is a topic of discussion at most meetings of the 501F Users Group. Next meeting of this independent user organization, chaired by Russ Snyder, plant manager, Arcadia-1 Power Station, will be Feb 21-24, 2016, at the La Cantera Hill Country Resort in San Antonio. Write russ.snyder@cleco.com for updates on meeting content.

Oil-mist lubrication helps protect against hot bearings, a combined-cycle O&M manager told the editors during a plant visit. He said the Alemite system, used for years in refineries and now at his facility, relies on continuous oil/air flow and positive pressure to keep dirt and other contaminants out of the bearings while helping to maintain optimal lubricant flow at all times.

The value of RCM was summarized this way by a maintenance manager at a combined-cycle facility that had implemented a rigorous and extensive reliability-centered maintenance program:

      • Infrared windows have been installed “everywhere,” so 4.16-kV electrical components and other equipment can be monitored easily to provide information for predictive maintenance.

      • PdMA Corp’s MTAPs data acquisition portals have been installed on all critical motors to allow safe online health assessments without LOTO restrictions, resulting in “big cost savings and safety improvements.”

      • The plant has not lost an RO pump, once a key headache, since the RCM program was implemented.

      • Persistent damage to circ-water-pump discharge expansion joints was traced to an improper procedure calling for startup with valve closed.

      • Failures of cooling-tower fan gearboxes have been mitigated by (1) balancing the fans, (2) replacing the original 12-blade design with a fan having six blades, and (3) more precise bearing lubrication. Fan drivers are now cycled automatically based on run hours. Also, all risers have been equipped with motor-operated valves (MOVs) and system pressure is maintained as a constant via bypass valves to avoid broken pipe downstream.

      • The RCM pointed to improper layup of evap coolers in winter based on a significant media fouling event in summer.

      • Closed cooling-water circuitry serving the gas turbines was eliminated. GT cooling water now is tied into the cooling-tower circuit. The original system “always ran hot” and posed limits on generator cooling during hot summer days, as well as on lube-oil coolers. The closed cooling system also was linked to GT trips at a cost of $500,000 each.

      • Information gathered as part of the RCM program also suggested the following improvements, which were implemented: (1) Installation of Cutsforth brushes to improve safety and protect against trips; (2) replacement of MOVs with air-operated attemperator block valves to protect against leakage of water into steam lines; and (3) use of a new digital device and software for roving operators to record rounds data and facilitate its transfer into the eDNA (InStep Software LLC) data historian server located outside of the plant’s firewall.

Safety never sleeps. A recent report from newspapers nationwide reveals that a man delivering sheet rock to a construction site was killed when a tape measure, weighing about l 1b, fell 50 stories and hit him in the head after ricocheting off equipment located 10 to 15 ft off the ground. Delivery personnel, like contractors, must wear appropriate safety gear when inside plant boundaries.

Heat stroke is the most serious form of heat injury and is a medical emergency. One plant’s quarterly safety bulletin advises that if you suspect someone has heat stroke—a/k/a sunstroke—call 911 immediately and cool the patient until paramedics arrive. With summer coming, be aware that the hallmark symptom of heat stroke is a core body temperature above 105F, but fainting may be the first sign. Other symptoms may include: throbbing headache, dizziness, lack of sweating despite the heat, muscle weakness or cramps, nausea and vomiting, rapid heartbeat, rapid shallow breathing, behavioral changes (including confusion, disorientation, staggering), etc.

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