Users will believe their colleagues in the trenches before they’ll believe what a vendor says. Four highly regarded user presentations made during the LM6000 breakout sessions, chaired by Andrew Gundershaug, plant manager, Calpine Solanno Peakers, are summarized in this issue of CCJ ONsite:
These presentations can be accessed by qualified WTUI user members at www.wtui.com.
LM6000PF engine swap. A speaker representing a 3 × 1 LM6000PF-powered combined cycle reviewed with breakout session participants lessons learned in changing out an engine. GE provided the technical advisor for the change-out, the owner/operator the labor. The plant has a spare engine to rotate through the plant.
First step: Assure compliance with applicable GE service letters and product bulletins—these in particular:
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SL6000-09-01, “Load Test of Package Crane.”
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PB-LM6000-IND-0295, “Trolley Replacement.”
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PB-LM6000-IND-0310, “Crane Interlock Assembly.”
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PB-LM6000-IND-0238 R2, “PT Perkasa Chain Hoist Replacement.”
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PB-LM6000-IND-0284 R1, “Turbine Lift Fixture Load Pin.”
In parallel with this effort, schedule an inspection for the package crane using a 10-ton test weight. Keep in mind that the crane hoist can be moved out of the package for inspection and testing once the air piping is removed. Also, remember to thoroughly review your rigging and lift plans, check spares inventory, and order consumables and other parts required.
Staging is next. Preparations include mobilization of H-frame and components, shim material to level beam, engine dolly, lift fixture, rigging, fuel manifold support fixture and bolting, test weights, forklift or zoom boom for handling heavy parts and the H-frame assembly.
Key steps in engine removal, the speaker said, include the following:
1. Offline water wash at shutdown and lock-out/tag-out (LOTO).
2. Disassembly according to GE WP 3010 with the following parallel tasks:
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Air piping over the engine and bleed valves.
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Instrument cabling, oil piping/tubing, clutch removal.
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Generator shaft coupling, VBV boot, and air inlet boot. Be aware that the VBV expansion joint is heavy; use a forklift and pallet skid to remove.
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Expansion joint, clamshells, slide exhaust diffuser.
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Fuel supply piping and installation of the fuel-manifold support fixture (WP 3015).
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H-frame assembly and load test.
3. Position engine lift fixture, loosen mounts, and check the center of gravity.
4. Remove stanchions and keep track of shims.
5. Lift engine with hoist and roll out of package onto the dolly.
When reinstalling the engine, keep these points in mind:
1. Allow the engine lift fixture to support the machine until alignment, shimming, and stanchion torque-up are complete.
2. Remove lift fixture and return package crane to storage position.
3. Align exhaust diffuser and install clamshells.
4. Reassemble components and remove fuel manifold support.
Lessons learned included the following:
1. More mechanics and helpers were needed. Plan for the next outage is to have two-man teams to handle the exhaust section, air piping, etc.
2. Have on hand shims of varying thickness to minimize delay time “looking.”
3. Exhaust diffuser, clamshells, and expansion joint not shown in the OEM’s manual; have spare fasteners on hand.
4. Protection: Have an assortment of plastic plugs and caps readily available to labor.
Real-time performance monitoring. Important subject, but time constraints prevented dropping below about the 10,000-ft level in terms of detail. The speaker, a US Navy “grad” with three decades of non-military LM experience—including plant operator, plant manager, and performance engineer (last seven years)—discussed performance monitoring in broad terms, touching on the following topics:
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Requirements for real-time performance testing.
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Historian.
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Correction factors/curves.
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Degradation.
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GE apps.
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Data resources—test cell or in-situ.
Starting with the last bullet point, he explained that test cell data are good for verifying engine guarantees but possibly not a realistic benchmark for plant work because the instrumentation and engine configuration may not be the same in the test cell as they are in the plant. In-situ data provide a true “apples-to-apples” comparison for performance assessments. Be sure to gather plant data with all equipment running, he advised—including the HRSG, if installed. Where actual and expected results are not in agreement, send to the OEM to find out what’s causing the performance degradation. Example: Is the engine getting dirty?
Remember to correct performance calculations, he continued, for gas-turbine inlet temperature, barometric pressure, elevation, inlet pressure, exhaust pressure, fuel temperature, humidity, etc.
GE apps (applications for packaged power solutions) include a non-guaranteed performance estimator, which can assist in assessing how well your plant is performing. The speaker said your customer service manager should be able to get this for you through the company’s Turbine Performance Estimator Portal. The CSM also should have access to runtime degradation curves, another valuable tool.
One attendee asked how to account for water injection/Sprint™. The response: Use GE apps. Measuring washing effectiveness was another area addressed as was the impact of fuel quality and temperature on heat rate.
Potpourri: Best practices, lessons learned. A plant manager recently assigned to a generating station equipped with two 2 × 1 combined cycles powered by LM6000PF engines, walked attendees through slides prepared by his predecessor. The short presentation offered several best practices/lessons learned, including the following:
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A new monorail system to facilitate engine removal. It enables plant personnel to place the engine directly into the shipping container, eliminating the typical pick from a dolly to the container (see following presentation). The monorail also eliminates interference of the filter house with the crane. Eliminating picks, of course, reduces the risk of damage.
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Bushing changes. The speaker recalled the HPC event on his first day as plant manager when a nut backed off a VSV arm. Corrective action was to put RTV silicone on bolts and to replace all nuts when bushings were changed. The speaker noted that the OEM’s manual doesn’t mention the need for new nuts or the use of RTV.
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Air/oil separator drains. Plant experienced freezing of both the large and small drains. Corrective actions: Shorten the pipe on the large drain to eliminate a low-point trap and add heat tracing to the small drain. Problem solved.
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Kidney loop filter. High concentrations of water were evident in all oil samples. LP Sprint™ operation got the blame. Corrective action included addition of kidney-loop filter systems on all lube-oil tanks. Result: Water was removed and oil cleanliness improved.
