World-class competition from third-party suppliers keeps OEMs on their toes

“PSM 501F Technology Day,” a comprehensive three-hour invited workshop at the 2015 conference of the 501F Users Group in the Westin Savannah Harbor, February 24, gave owner/operators a preview of the in-depth information-sharing they can expect from the fleet’s leading third-party products and services supplier at future meetings, which will not have OEM participation. Recall that Siemens Energy Inc elected to start its own “user” conferences for owner/operators of the company’s F-, G-, and H-class machines; the first meeting is scheduled for September 14-17 in Orlando. Contact Dawn McCarter for more information.

PSM President Dr Alexander Hoffs took the podium first and began with a quick status review of the pending GE Alstom Alliance, still a work in progress. At PSM, it’s “business as usual,” he said. Next was an update of the company’s facilities, now solidly global with shops and engineering offices in multiple European and Asian countries, the Middle East, and North America. PSM’s safety record followed: one lost-time accident in the last five years and only six OSHA recordables in 2014.

Hoffs reminded the group that the company opened for business just 15 years ago and got its big start designing, developing, and manufacturing hot-gas-path (HGP) and combustion-system parts for Calpine Corp. Only eight years since its acquisition by Alstom in 2007, PSM’s line card now includes complete asset support—including capital parts, repairs, field services, and monitoring—for B-, E-, and F-class models made by GE, Westinghouse, Siemens, and Mitsubishi-Hitachi.

The speaker said the company had almost 100 gas turbines under some type of long-term parts and/or services agreement. Portfolio highlights include:

      • All HGP components for Siemens and Mitsubishi-Hitachi F-class engines, most components improved from the original OEM offering.

      • Low-emissions combustion systems for B-, E-, and F-class gas turbines.

      • Complete compressor solutions for multiple frames.

      • Rotor repairs and life assessments.

      • Dynamics and engine monitoring, and continuous tuning optimization, with PSM’s AutoTune system.

In his concluding remarks, the speaker organized for attendees additional services that PSM provides in one summary slide called “Shaft Line Products and Services.” The various offerings were overprinted on the cross section of a combined cycle in bullet-point fashion under the subject headings of plant services, HRSGs, steam turbines, plant assessments, and generators. The message: PSM is equipped to handle the total plant needs of its customers.

Tim te.Riele, VP products and platforms, presented the company’s product-development approach and primary objectives. He stressed that current company initiatives focus on lifecycle cost reduction, upgrades, and products/services to extend the lifetime of F-class assets. te.Riele added that the platform approach, demonstrated successfully by the company, would be used to move into advanced frames. This approach enables PSM to leverage its own technology solutions across multiple OEM gas-turbine fleets.

Compressor solutions. Greg Vogel, manager of airfoil engineering, divided the compressor into four sections (Rows 1-3, 4-8, 9-15, and 16) and explained how designers/engineers addressed the OEM’s FD2 and FD3 hardware issues. Note that PSM’s compressor blades for these two frames are piece-wise compatible with the OEM’s, diaphragms for standard and modified (CM2) casings are set-wise compatible.

The company installed its first diaphragms for Stages 1-3 in April 2010, which based on monitoring and inspection results thus far, are expected to run for 100,000 equivalent base hours (EBH) without repairs. Fleet leader among the 30 sets of PSM’s S1-S3 solution is closing in on 25,000 EBH and 300 equivalent starts (ES). The speaker recalled the experiences of operators with the original OEM parts, where few, if any, sets reached their intended maintenance interval before replacement was required.

Vogel said features of the PSM diaphragms contributing to long life include forged singlet airfoils (no welding), a bolted OD ring assembly to improve damping and permit replacement of individual airfoils, ID seal box bolted to a robust platform, use of coatings to reduce wear and tear, and split-line jumper pins that eliminate twist. Diaphragms compatible with CM2-modified casings are now available and include the same design improvements.

Diaphragms for Stages 4-8 were based on the successful design used for Stages 1-3, with honeycomb replacing knife-edge seals. At the time of the 501F meeting, seven sets had been sold and the fleet leader had operated nearly 8000 EBH/120 ES. Stage 9-15 diaphragms, designed for 100,000 hours without repairs, have forged and machined airfoils and ID ring to avoid cracking associated with welding. Fleet EBH leader is in the low five figures. The Stage 16 diaphragm, running successfully since March 2013, is similar to those in the Stage 9-15 section of the compressor. It incorporates a robust anti-rotation feature in response to an issue identified with the OEM’s design.

Combustion solutions. Peter Suttaford, director of R&D, focused on PSM’s so-called “drop-in” and FlameSheet™ combustion systems. The first is a “conventional” dry low-NOx offering with technology enhancements enabling extended turndown (a 5% to 10% improvement over the original equipment) and designed for a 25,000-hour/900-start overhaul interval. Specifics: 25 ppm NOx and CO at full load on gas (42 ppm NOx wet); turndown to 50%-60% load without exceeding 10 ppm CO.

The drop-in combustor is compatible with the OEM’s equipment at both the component and system levels and some components have more than a million hours of successful fleet operation to prove it. No changes are required to WDPF/Ovation™, TXP, or T3000 controls, or to the fuel skid. Simply pull out the old and replace with the new.

The first system installed, recently reached a full HGP interval. It operated for 23k EBH and the customer decided to take the outage then rather than waiting the full 25k. For the basket and support housing, this was the first proof of capability. Fig 1 shows the typical basket condition after cleaning. Note that these parts do not exhibit some of the typical distress modes found in 501F baskets. Although a full inspection and assessment has not been completed, it’s expected that only light repairs will be required. In addition, these baskets will be upgraded to an improved cooling scheme on the liner before they are returned to service. Further updates on this topic will be presented at the upcoming CTOTF™ meeting in Coeur d’Alene, September 20-24.

PSM 501F Fig 1

Transition pieces and pilot nozzles had demonstrated extended operation previously. Those components are now beyond 50k EBH. Expectation is four-interval component life for all parts and lower repair costs at each part turn. The positive outlook is based in large part on reduced operational risk. The speaker said design and flow-control attributes increase the dynamics window for safe operation. Translation: greater flashback and NOx margin.

Suttaford next explained how the company’s FlameSheet combustion system works—certainly news to most in the room with nearly half the group first-timers. CCJ ONsite had alerted all users to FlameSheet’s capabilities in conjunction with its 7F Users Group coverage about a year ago. One of the most interesting features of the combustion system is its potential 501F/7FA cross-platform part commonality, allowing owners with both engines to reduce parts inventories. Other benefits offered by FlameSheet include the following:

      • 25,000 EBH or 900 ES maintenance interval.

      • Additional 20%-30% load turndown compared to conventional dry low-NOx combustors.

      • Sub-9-ppm NOx and CO emissions from extended low load to base load.

      • Wide fuel flexibility (30% on the Modified Wobbe Index).

Commercial update: When the 7F report referenced above was published, FlameSheet capabilities had been demonstrated only in a high-pressure test rig operating at engine conditions. The first commercial system has been running in a 7FA since spring (Fig 2) and has demonstrated the following in normal operation:

      • Additional 20% load turndown without durability impact on the HRSG.

      • Sub-9-ppm NOx and CO performance with low dynamics across the operating range.

      • Stable sub-6-ppm NOx at base load and during a +45-deg-F overfire test.

PSM 501F Fig 2

While PSM had no 501F orders for FlameSheet as of this session, Product Line Manager Brian Micklos told the editors customer interest is high and the company is ready to support a 2016 installation.

Controls. Jesse Sewell, director of service engineering, followed Suttaford at the podium. Sewell is known to long-term CCJ subscribers for sharing his work in control-system troubleshooting, combustion tuning, and in the development of combustion dynamics monitoring systems (CDMS). He outlined how the company provides controls-related services across seven different platforms to support customers in plant operations and PSM technology initiatives for design and development.

PSM’s AutoTune, a mature product with years of commercial experience, underpins the company’s so-called FlexSuite™ for the 501F. Among the platform’s options to improve operation, it enables custom controls upgrades to optimize startups/shutdowns, operate the engine over a wider load range, improve performance, extend component lifetimes, and burn a variety of fuels successfully. The potential benefits include improved reliability, fewer forced outages and trips, higher rank in the dispatch order, and ability to support additional ancillary services for improving the bottom line.

Sewell said a significant AutoTune upgrade should be ready for commercial deployment during upcoming fall outage season. Features include lean-blowout transient tuning, an improved graphical interface, protective “stop-tuning” feature, configuration-tool display improvements, and CDMS through Modbus. The last enables operators to see dynamics in the control room.

Sewell also announced the fall availability of PSM Virtual Plant, a full tie-back simulator built to support controls replacement and expansion projects as well as the company’s technology initiatives in operational and protective schemes and communications protocols. Virtual Plant has been tested successfully for work on six different engines/configurations—including 501F simple-cycle facilities.

PSM 501F Fig 3Rotors. Chad Garner, manager of R&D engine integration, talked about PSM’s rotor-life management capabilities; 501F rotor consumables; field service staff to handle rotor removal, inspection, ship, and reinstall; engineering support; and shop capabilities for rotor repair, life extension, upgrade, and high-speed balance.

Other topics included PSM’s rotor tie-bolt upgrade and belly-band improvements, both of which are incorporated into the unfired 501F rotor the company now has available for exchange (Fig 3). This is an important offering for owner/operators, for example, when a rotor is damaged in service and the length of the shop stay would have a significant impact on the plant’s bottom line.

Garner ran through the company’s evaluation program to determine if a lifetime extension of up to two major inspections is possible for rotor at or near the recommended hours life limit. Advanced NDT is necessary for a condition-based evaluation, he said. PSM uses proprietary NDE technologies to detect surface flaws and additional techniques to find volume flaws. If a crack is identified, probabilistic and deterministic methods are used to evaluate component lifetime and recommend an operational strategy to the owner. The company completed its first 501F rotor lifetime evaluation in spring 2015.

Exhaust cylinder and manifold. Garner did the heavy lifting for the well-prepared PSM team, making two presentations back-to-back on subjects of major interest to attendees. His second presentation was on the company’s exhaust (cylinder and manifold) solution, which promises a reduction in O&M cost and elimination of a big headache.

Garner stressed reliability in his remarks on the exhaust cylinder, noting that PSM’s total redesign—compatible with FC, FD, and FD2 models and his company’s upgrade packages (specifically the GTOP6, see below)—certainly is a solution for issues driving component replacement because of severe degradation. Engineers studied the problems experienced in the fleet and addressed the major concerns in their redesign—including casing and strut over-temperature, which can cause the rotor to drop; exhaust recirculation; extensive liner cracking, thermally constrained strut shields, etc.

Completion of PSM’s first exhaust cylinder is expected in September 2015; a second unit is right behind it in the manufacturing process.

Turbine and upgrade solutions, the final topics on the program, were the focus of Director of Airfoil Engineering Chris Johnston’s remarks. With time running out, Johnston highlighted the R1 turbine-blade features of PSM’s Gen2 (2008) redesign. The Gen2 was designed to address issues seen fleet-wide—including airfoil liberation attributed to high-cycle fatigue, platform and seal-pin liberation, spallation of thermal barrier coating from the platform and oxidation of base metal, platform cracking, and leading-edge oxidation/erosion.

Gen3 R1 turbine-blade improvements contributed increased component durability and easier repairability for high-starts units thereby reducing lifecycle cost. Design improvements include a material change to greatly improve fatigue margin, and a cast-in tip plate. First components were released to the fleet in 2013 (Fig 4).

PSM 501F Fig 4

Johnston continued with highlights of other enhanced turbine components, such as these:

      • R2 vane. Enhanced platform design to minimize hot gas ingestion, platform oxidation, and repair scope.

      • R3 vane. Material upgrade to combat creep, thereby reducing the risk of rotor rub; improved thermomechanical fatigue behavior in cyclic operation. Expected to run 50k EBH without repair.

      • R1 ring segment. Improved mate-face cooling and coating.

      • R2 ring segment. Upgraded material for robust multi-interval part design driving reduced lifecycle costs.

The speaker closed out the session with an overview of the Gas Turbine Optimization Program (GTOP6) which leverages PSM-improved component technologies—including several of the enhancements noted above, plus others. When operated in Performance Mode, simple-cycle output from a 501F is expected to increase by 9%, efficiency by 3.4% (1.6% for a 2 × 1 combined cycle). In Maintenance Mode, the HGP interval is increased from 25k to 32k, with reduced, but still significant, performance benefit. Multiple installations of GTOP6 in a 501F are planned for spring 2016.

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