Siemens engineers speak to issues, solutions, technology developments for F, G, H frames

Siemens Energy Inc’s second technical conference for owner/operators of its F,G, and H gas turbines, held Sept 18-21, 2016 at the Rosen Centre in Orlando, was rated a “success” by attendees sharing their views after the meeting. Nearly 150 global customers from 65 companies participated. CCJ’s editorial team, unable to attend because of schedule constraints, asked Christie Robinson, representing the OEM’s frame-owner office and product-line managers, to prepare the summary below.

This brief roundup will help identify subject matter on the program of importance to your plant/company. Then it is up to you and your colleagues to access specific presentations via the Customer Extranet Portal (CEP). Contact the Siemens representative for your plant if you have difficulty accessing the information needed.

Ed Bancalari, head of Siemens’ large-gas-turbine product line opened the meeting with a video on what it takes to shape the future. His presentation focused on conference improvements, a regional view for each frame, an understanding of customers’ challenges, how innovation is being used to increase customer value, digital portfolio, and a reminder to keep the entire plant in mind when it comes to expanded-scope solutions. An interactive poll was conducted to help the OEM better understand customer information requirements, concerns, etc.

Highlights of the meeting included presentations by the OEM’s technical experts, closed user sessions, networking opportunities, a vendor fair, and a multi-day Siemens product technology and innovation showcase which included guided tours (new in 2016) conducted in English, Spanish, Arabic, and Korean.

The following links facilitate access to the content summaries of greatest interest to you:

Mature F-class engines

Shantanu Natu, mature F frame owner, led the session covering the F through FD3 engines. Chris Muller opened with a presentation on the air separator and torque tube, reviewing rub events and their root cause, and Siemens mitigation recommendations. Included was an update on the recent air-separator axial-rub event experienced in the fleet, plus details on the FD6 hybrid rotor as a design improvement that eliminates the air separator.

Bill Borman followed Muller with a review of rotor-air-cooler (RAC) filters that covered different designs and fleet experience. Mike Olejarski then addressed bellyband configurations, fleet status, and current recommendations.

Michael Hale’s presentation on the R4 turbine-blade seal-pin RCA included a status report on design improvements—such as the enlarged seal-pin slot modification, blade springs, and optimized platform gap for the R4 blade. Chris Wetzl followed with a turning-gear time-reduction product developed by Siemens. In addition to reducing the time spent on turning gear, it provides peaking units instant-start capability.

The following session covered fleet findings on specific sections of the gas turbine—such as the compressor, combustor, turbine, casings, and rotor. Included were the effects of component findings on operation, performance, and repairs, as well as available improvements, controls, and O&M guidelines. The presenters were Dan McLean (compressor), Eric Schwirtz (combustor), Veronica Arocho-Pettit (turbine), and Marty Hall (casings).

Steve Dowman next updated the group on methods to address turbine-cylinder four-way joint leakage—such as alternative bolting sequence, sealants, box modification, and seal weld for vertical joint. Also covered: A status update on weld-repair recommendations to address four-way-joint cracks. Natu closed out the first day with a presentation on Siemens’ long-term commitment to the F-class frame.

On Day Two, Jorge Cobian updated users on the DC lube-oil system, covering product bulletins and maintenance recommendations. A blade-path-spread case study by Gary Hildebrandt followed.

Ben Bassord then conducted a voice-of-the-customer (VOC) session on power diagnostics. It covered diagnostic-findings and monthly operations reports, 24/7 hotline support, and communication between plant and power diagnostics center.

The next session focused on the actions taken by Siemens to improve the quality of new parts (presented by Robb Chubb), repair parts (Anne Schneider), and field services (Mike Guerrero and Doug Hoffman).

Mike Salvatore presented case studies and lessons learned on plant-modernization and plant-upgrade solutions, including the following: FD6 partial package with ULN 3.0, advanced low-load-turndown 2.0, FD3 thermal performance upgrade (TPU) and single-piece exhaust (SPEX), and DF42-to-DLN conversion.

Last topic of the day was digitalization, presented by Edwin Castaneda. Topics included the Sinalytics platform, digital services, and product portfolio. The speaker showed how digital services can improve plant availability, efficiency, and flexibility. Users later met in a closed session to coordinate feedback. The steering committee of engine owners/operators communicated the feedback to Natu and his team.

Advanced F-class engines

The Siemens SGT6-5000F advanced frame sessions (F4, F5, F5ee), conducted in parallel with the mature F sessions, were led by Service Frame Owner Cristi Nemeth. Following her opening remarks, Brian Bohinski updated users on the market penetration of the advanced Fs, stressing again Siemens’ commitment to continued development of F frames.

Next, Milt McCarty reviewed the advanced F combustor and turbine validation and inspection results from the fleet-leader units. Perhaps the most important point made: The advanced F combustor and turbine have successfully demonstrated reliable operation to the extended intervals of 25k and 33k EBH (equivalent baseload hours), respectively.

Javier Jimenez updated users on compressor-inlet-manifold crack indications found on some F5 units. Acoustic blankets were said to dampen the vibration that cause the cracking; they are available as a product improvement.

Dustan Simko and William Clark reviewed experience with the advanced F compressor. Simko’s presentation addressed minor issues affecting the accuracy of variable-guide-vane (VIG) angle measurement and improvements to angle-measuring instruments introduced in new-unit production and also available for retrofit in service units.

Clark discussed the overall status of the advanced F compressor, including an overview of the design progression from F4 to F5 to F5ee. Of particular note in his presentation was the status of the compressor lock-bolt issue highlighted in coverage of the first meeting. No further incidents of the lock-bolt issue have been reported, and mitigations are available for installation during opportunity outages.

Peter Rimmington closed out the compressor topics with a discussion of limits regarding the field blending of compressor airfoil damage.

McCarty returned to the podium to share findings observed in the advanced F combustor; Jonathan Mount did the same for the turbine section. Barton Pepperman followed with an update on the turbine exhaust, including the favorable field experience with SPEX as well as with resolutions to current issues with the expansion joint and the F5ee HEX strut-support blocks.

Olejarski discussed the Direct Air Injection System (DAIS), designed to mitigate casing thermal distortion after shutdown and reduce the probability of blade tip rubs that could debit unit performance. Simko returned with a technical review of the lube-oil system and bearings used in the advanced F, followed by Cobian on product improvements and recommendations to enhance the reliability of the DC lube-oil system.

Hildebrandt was next with an educational discussion of operational support provided by service engineering and the Power Diagnostics Center (PDC), including a case study of a blade-path-spread issue that was resolved by successful collaboration among the customer, service engineering, and the PDC.

Day Two started with a closed session for users, followed by presentations by Chubb, Schneider, Guerrero, and Hoffman updating attendees on the application of quality processes in new manufacturing, repair, and field service.

Abhijeet Tiwary and Edwin Castaneda presented on advanced technologies and digitalization, the former covering advanced NDE—including online monitoring of flow-path components and advanced manufacturing methods. Castaneda outlined Siemens’ approach to the use of data analysis for improving performance and reliability. Service Frame Owner Nemeth reviewed the F-frame evolution and reiterated once more Siemens’ commitment to the fleet.

Greg Perona made the final presentation of the conference—a comprehensive look at mods and upgrades available to owners. It included multiple thermal-performance packages, wet compression, and gas-turbine autonomous control optimization. Later, the users met in a closed session to provide feedback to Nemeth and her team.

G fleet

The topic generating the most discussion in the 501G session, chaired by Frame Owner Mark Carter, was an update on the R1 turbine-blade fracture issue. Rusty Van Hoose presented the latest fleet findings and conclusions from the RCA. The fracture was attributed to a flow disturbance caused by severe burn-through on the leading edge of the R1 vane.

Frank Ayoung-Chee followed with a presentation on the corrective actions to address R1 vane distress. Instrumented testing of the baseline airfoil was conducted to verify and calibrate analytical models. The results were used to develop a mitigation design for the R1 vane which increases backflow margin, improves impingement cooling, and supplies additional film cooling to the leading-edge area of concern.

The design mod can be implemented on the existing inventory of R1 vanes to minimize the lead time for issue resolution. Instrumented verification testing of the new vane design is planned for this fall. Additional design work on the R1 vane is under consideration.

An RCA update also was provided by Manish Gurao on the turbine-rotor through-bolt failure. Although rare, these bolts can fail when debris accumulation contributes to high contact stresses, which are conducive to cracking by fretting fatigue. High-cycle-fatigue (HCF) cracking ensues, with overload rupture an eventuality. The discussion focused on the design mitigations to provide additional margin against failure.

The primary path is the application of low-plasticity burnishing, a surface treatment intended to greatly improve a through-bolt’s margin against both fretting and HCF crack initiation and propagation by adding a deep compressive residual stress field to the bolt surface. Additional potential bolt/disk redesign efforts and the recommended mitigations for the RAC circuit to minimize debris accumulation also were presented.

The upcoming performance upgrade offering for the 501G gas turbine, the Next Gen combustion system, was presented by Jim Pettit, who covered system benefits and design, test results, and implementation timeframe. Next Gen promises increases in power output, operating reliability, unit availability, and starting reliability across the ambient operating temperature range.

The combustion-system components are based upon advanced fleet design and experience with the ULN system. They are robust, designed and built to withstand higher firing temperatures and to offer the potential for extended operating intervals. The system recently completed a rigorous battery of tests in a test rig that confirmed performance goals for the new combustion system had been achieved—including lower emissions and an increase in flashback margin.

The ignition system, now static, was said to have performed flawlessly, providing high confidence in the starting-reliability improvement experienced with the advanced-frame designs. Turbine components have improved thermal-performance coatings to accommodate the higher firing temperatures of the latest machines. Multiple components, including the R1 turbine vanes, have an improved cooling scheme. Implementation and testing of the performance upgrade is planned for late 2017 to early 2018.

H fleet

Siemens 8000H engine owners and operators from around the world came together to the conference in Orlando for the second time. The agenda was developed by direct input from customers because a steering committee had not been formed prior to the meeting. However, this during the 2016 closed user’s session, a steering committee was selected by owner/operators to represent the 8000H user community.

   Dave Lawrence, the 8000H frame owner, kicked off the event which provided multiple sessions over two days. Below is a sampling of the sessions conducted:

      • Frame overview and fleet status included an announcement for a new web-based communications forum which will be trial tested and rolled as soon as practicable.

      • Fleet experience. Presentations allowed users to dive deeper into specific topics.

      • An 8000H vendor fair and parts showcase was conducted. Some of the latest technologies/components were on display and a customer interactive digital screen was available to further inform.

      • Mods and upgrades reflected how Siemens is working with users in the product development process.

Steamers, generators, controls

Multiple parallel-track breakouts were conducted following the gas-turbine sessions to update attendees on generators, steam turbines, and controls. A new breakout session at this year’s conference included guided tours of the parts showcase with expert engineers in multiple languages. Here are some notes from each track:

The generator team provided direct responses to requested topics on the AeroPac, Modular, and BIC fleets. Frame Owner Scott Robinson reviewed the installed generator fleet for the F, G, and H gas turbines, touting its high availability and reliability. An update on AeroPac spark erosion topic also was provided.

Justin England, Generator Service Engineering (GSE), gave a status report on the continuing RCA for AeroPac key-bar stud separation. Justin Shingle, manager of generator specialty services, followed with a review of the recent service bulletin for parallel-ring-tab inspection, plus inspection recommendations for the Modular generator product line.

GSE’s Jon Anderson conducted a tutorial on modal testing of the Modular generator stator endwinding before providing an overview of the SGen-1000A end-block service bulletin. Alex Oyler of GSE updated attendees on Performance Plus™ carbon seals, including a review of fleet operational history and the OEM’s ongoing work to improve this product.

Eric McDonald, director of generator specialty services, presented on new capabilities— including the elevated-frequency test and GVPI stator repair options. A Q&A session covered all generator topics, both on and off the agenda.

The steam-turbine sessions, led by John Walsh, engineering management, reviewed details of the KN and HE frames. Topics discussed included maintenance, outage planning, titanium blades, and a wide variety of available upgrades—including ruggedized hydraulic turning gear, EH skid upgrades for reliability, failed thermocouple simulations for continued plant operation with instruments that cannot be repaired with the unit online, coupling-bolt installation improvements, automated forced cooing, and a package of control logic upgrades for enhanced turbine operations.

The controls session was chaired by Tom Delia. Presentation topics included development status and field experience of the gas-turbine autonomous control optimizer (GT-ACO). This product line offers a fully autonomous and adaptive control strategy designed to provide continuous optimization for emissions, dynamics, and firing temperature while maintaining GT power output.

Session also included detailed presentations on the implementation of the SPPA-T3000 Release 7.2 pilot project implementation and the integration of the advanced operations “applications.” The criticality of cybersecurity and the implementation of best practices and requirements for meeting the latest NERC-CIP standards were presented as well.

2017 customer conference

Siemens Energy Inc’s engineering and marketing teams already are planning the next customer conference for owners of its F, G, and H gas turbines, motivated by the positive feedback received on the 2016 meeting. Plan is to have the next meeting in Orlando in September 2017. Keep up to date on Siemens’ plans by contacting Kelly Lewis or Dawn McCarter to receive details on the 2017 customer conference when they become available.

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