501F Users Group

There was a presentation or discussion of valuel in every time slot at the 2010 conference of the 501F Users Group, and not all were about the gas turbine. The change of pace provided by switching among several other topics of importance to attendees—including safety, electric generators, steam turbines, and plant management—helped maintain interest at a high level throughout the four-day meeting. Two optional sessions kickedoff the conference mid morning of Day One, giving attendees traveling on Monday time to register, get settled, and ease into the intense technical program.

Both sessions—one on generators, one on gas-turbine mods and upgrades—were presented by experts from Siemens Energy Inc, Orlando. The generator thread carried over into the afternoon with National Electric Coil’s Howard Moudy, director of service management, holding the attention of an SRO audience with a highpowered presentation on spark erosion and partial discharge. Moudy moves so qui ckl y through his material that taking meaningful notes is virtually impossible. So the editors asked NEC to share the content of that 501F presentation with all generator users by preparing an article on spark erosion and partial discharge for the upcoming 2011 Outage Handbook; you’ll be receiving that soon.

Users Only Break-out Session

A users-only breakout session on generators, chaired by Paul Terry, a member of the steering committee, wrapped up the afternoon. One of the best ways to keep up on generator technology and O&M between user-group meetings is to join, at no cost, the International Generator Technical Community online forum at www.generatortechnicalforum.org (ad, p 136). The site features 13 problem-solving forums and a rapidly expanding technical reference library.

There were more than 550 registered members of the “generator community” by year end 2010. Compliance issues and solutions associated with the NERC Critical Infrastructure Protection (CIP) standards (cyber security) are straining the limited management resources at many plants today. The steering committee invited Dr Matthew E Luallen to address the timely subject and then followed up with a user-only breakout moderated by Russ Snyder, chairman of the 501F steering committee.

The CIP track ran in parallel to the generator track, allowing attendees a choice of subject matter. Day Two Day Two was all users, all the time, with dozen or more presentations and follow-on discussion roundtables. Siemens Day was Wednesday and included detailed coverage of issues in the compressor, combustion, turbine, and exhaust sections.

The morning of Day Four was dominated by user discussion early and closed out with a presentation by Chip Thompson and Jason Yost of Mercer Thompson LLC on the changing nature of long-term service agreements. This information also is of interest to owner/operators outside the 501F family has been compiled into an article for the Outage Handbook.

Thursday afternoon was dedicated to steam turbines. This report presents the highlight s of a few user presentations and discussions conducted over the four-day meeting. To dig deeper, locate the user presentations on the 501F User Group’s website, which can be accessed through www.users-groups.com by registered members. If you qualify for membership in the organization but have not yet joined, this also can be accomplished on the website. Siemens presentations are accessible by owner/ operators of the OEM’s frames who apply for and are registered to access the manufacturer’s Customer Extranet Portal.

Safety Discussion

The first full day of presentations (Day Two) began with an open forum on safety concerns, practices, etc, with Steering Committee Vice Chair Ray Martens as the moderator. The half-hour session opened with discussion on safety procedures for the handling and storage of ammonia for NOx control, fall protection for gas-turbine mainte-2011 Annual MeetingFebruary 14-18Paradise Point Resort & SpaSan Diego, CalifCompressor, turbine share the spotlight501F steering committeeChairman: russ snyder, plant manager, Cleco Power LLCVice Chairman: ray Martens, plant manager, Iberdrola Renewables Incpaul Tegen, chief CT/I&C engineer, Cogentrix Energy IncIvan Kush, director of outage services (Siemens fleet), Calpine CorpMartha Leskinen, senior engineer, SRP  paul Terry, rotating equipment reliability engineer, PPG Industries Inc rene Villafuerte, plant manager, Comego SA de CV154 COMBINED CYCLE JOURNAL, Third Quarter 2010nance, management-of-change procedures, and drawing maintenance.

Scaffolding was a subject the group wanted to talk about. This thread covered training, inspection, procedures, etc. One user said that at his facility one plant employee is assigned the task of inspecting scaffolding daily. No one is allowed to change scaffolding except plant personnel tracking such changes or the contractor running the job. The recommended penalty for anyone violating this policy: Immediate dismissal.Confined-space welding got air time as well, with the combustion section a target area. Suggestion was to do everything possible to eliminate the restrictions that require the combustion section to be classified as a confined space. By so doing, you avoid rescue-team constraints. A question on the proper clothing for working on energized components was asked. One concern was related to cost: Do you buy or lease? A user who thought buying protective clothing was the way to go because of the high cost associated with leasing suggested to the others that they seriously consider leasing. His  experience:  The purchased clothing was not holding up well, even with no abuse.

He also pointed out that if you own the gear, you’re responsible for cleaning and fixing it; plus, new hires might not fit in the clothing you have available. The lessor assumes responsibility for providing clothing to fit the employees you have, for cleaning, and for any repairs. What about fatigue considerations during a long outage? Fatigue is known to compromise safety. One school of thought was that no one should work more than six days a week, another said workers could get by with one day off every two weeks. Martens assumed the role  of speaker when the open discussion period ended. The subject was his plant’s experience in implementing a cornucopia of best-in-class performance upgrades from Siemens, each of which had satisfied the OEM’s rigorous commercial test criteria but collectively had never been installed on one engine.Martens is plant manager of Klamath (Ore) Cogeneration, a 2 × 1 501FD2-powered combined cycle. Owner Iberdrola Renewables wanted the ultimate in flexibility at Klamath: A base-load unit capable of daily cycling. Here’s a summary of what the plant achieved with the upgrades:n Increase in generating capability of up to 6% at base load.n Improvement in base-load heat rate of up to 2%.

Better part-load heat rate.n Turndown to 50% of rated capacity without exceeding 10 ppm CO (when ambient temperature is between 59F and 95F.n Opportunity to reduce total emissions during engine startup.n Increased SCR efficiency at low load.n Extended intervals between overhauls. For detai l s on the Kl amath upgrade, access www.ccj-online.com/archives.html, click 3Q/2009, click “Klamath gets better with age” on the cover. Strongback diaphragm .   The first of nine relatively brief (typically 15-20 minutes each) “issues presentations” glued the eyes of virtually all attendees to the screen. This is considered by many owner/operators as the most important part of the meeting. The idea is to share experiences and solutions to avoid a repeat incident; it’s what user groups are all about.

The owner presenting said a rapid downward slide in compressor performance reduced power output of one 501FD2 by about 10 MW over a period of about 10 days. Initial prognosis was carryover caused by an inlet evapcooler issue. Unit was removed from service to correct the problem. Personnel discovered a plug weld missing from a R2 strongback diaphragm with 13,000 service hours ( F i g   1 ) .   T h e   l i b e r a t e d  we l d   t r a veled down the compressor, damaging many blades in the process. Damage was consistent with the size and shape of the plug. R1, R2, and R3 all were affected and all were replaced. Several blades also were replaced in stages further back in the machine. The speaker noted that the OEM was still investigating the event, which is not believed related to the carryover issue. Siemens was said to be reviewing the design and use of restraint pins introduced to constrain the motion of the inner shroud at the ends of the strongback segments.Its compressor designers added to the collective knowledge on this issue during Siemens Day.

The problem reportedly had not been associated with any other machine in the fleet at the time of the presentation. The bottom line: Only R1 blades were impacted by evap-cooler carryover; most of the performance loss was attributed to damage caused by pin-balling of the plug weld, which was never found. R2 ring-segment side-seal libe  r a t i o n .   A borescope inspection scheduled for one of the two 501FD2s at the next presenter’s plant revealed extensive damage. The machine was operating normally with no significant indications other than those exhibited on one of the combustor cans. Investigation revealed a broken UV detector tube and FOD on R3 blades (Fig 2). Parts of side seals liberated from R2 ring segments were found while looking for missing portions of the detector tube that went downstream (Fig 3). The presenter said the same phenomenon—often referred to as seal “walk-out”—had been experiexcellent reputations. The bad news i s   that  DCS des igns  are  cont inually evolving. New features are introduced regularly and objective system comparisons can be challenging. P e r h a p s   t h e   w a y   t o   m a i n t a i n your   sani ty  throughout   the  selection process is to decide at the outset, before speaking with sales people, exactly what features you want your new control system to have and the level of vendor support you e x p e c t .   N o t   m u c h   d i f f e r e n t   t h a n purchasing a new truck. Last thing you want to do is to walk in a dealership and ask “Why do I want to buy this vehicle?”

Vendor alternatives

If you’ve been  in  the power  bus ines s   for  a couple of decades, many names probably come to mind when you think of control-system suppliers. But you’re looking at today and the future, at what is and will be, not behind at what was. The editors have heard the names of only three vendors at user-group meetings in the last five years when owner/operators of gasturbine-based generation discussed DCS upgrades: GE Energy, Siemens Energy, and Emerson Process Management (Ovation®). Upgrades to GE control sy stems typically are done by the OEM although a few installations have t rans i t ioned  to Ovat ion.

Siemens and Emerson battle head to head on upgrades for WDPF. Siemens’ T3000 is selected most often for Teleperm XP (TXP) upgrades although Emerson has had some success as well. All three vendors have been successful in upgrading ageing systems supplied by others to the Mark VI and VIe, T3000, and Ovation. As mentioned earlier, deciding on the capabilities you want your new DCS to have can be challenging. Back to the truck analogy: Do you want the stripped-down version—such as the T3000 that was offered when the system debuted at the end of 2003—or the fully loaded version, or something in between? The T3000 serves as a good example here because the basic DCS can be enhanced with by adding one or more “extras” as you might when ordering your truck.

Here are the five independent  add-on modules   currently offered:n D3000 Diagnostic Suite essentially identifies impending problems with rotating equipment. Think of it as an early warning system.n E3000 Electrical Solutions incorporates generator protection, unit and gr id protec t ion,  exc i tat ion systems, medium- and low-voltage switchgear, synchronization, voltage regulation, metering, UPS, etc.n M3000 Energy Management is a fleet-wide monitoring-center solution.n P 3 0 0 0   P r o c e s s   O p t i m i z a t i o n enables enhanced performance and higher profitability.n R3000 Turbine Control assures h ig h   re l i a b i l i t y   a nd   a v a i l a b i l ity, improves operating flexibility, reduces maintenance cost, etc. By contrast, Ovation reportedly has the same features but they’re all rolled up into the basic offering. For example, in January Emerson announced  that   i t  had  integrated machinery protection and prediction of critical mechanical equipment into Ovation. The company’s announcem  e n t   s a i d  ,   “  T h i s   n e w   c a  p  a  b  i l i t y directly supports power generators’ drive for improved plant availability and performance by providing machinery health feedback. . . .”

Finally, here are some articles on control sys t em upgrades  that  you might want to access at  www.combinedcyclejournal.com/archives.htmlto gain from the experiences of your colleagues:n Click 2Q/2006, click “Upgrading controls to maximize performance, availability” on the issue cover.n Click 4Q/2007, click “How one projec t   can def ine a  company’ s capabilities” on the issue cover, scroll to p 67.n Click 2Q/2009, click “Clark Station: Complete makeover” on the issue cover, scroll to p 69.n Cl i c k   3Q/ 2 0 0 9 ,   c l i c k   “Kl ama t h gets better with age” on the issue cover, scroll to p 115. ccjWWW.PROCESSCONTROLSOLUTIONSLLC.COM  601-310-1686DCS RETROFITSAS-BUILT DRAWINGSFACTORY ACCEPTANCE TESTINGCOMMISSIONINGPROJECT MANAGEMENTOVATION/WDPFOPTIMIZATIONRELIABILITY ENHANCEMENTSALARM MANAGEMENTTRAININGTUNINGSERIAL INTERFACESReprinted with permission from the Combined Cycle Journal, 4Q/2009.9 Life cycle rprnt.indd

4 7/1/10   2:41:02 PM3. side seal “walks out” from between adjacent ring segments2. part of a uV detector tube liberated, traveled downstream, and damaged R3 blades and other components156 COMBINED CYCLE JOURNAL, Third Quarter 2010501F users groupenced previous ly on R1  r ing  segments and on ring segments “right out of the box.” A root cause investigation was ongoing at the time of the presentation. R2 rubbing did not appear to be a factor and no obvious problems could be traced to the installation of the ring segments themselves. Visual inspection revealed poor quality of some welds holding seals in place and inconsistent staking of the seals on others. Six ring segments were submitted for metallurgical analysis: two had seals missing, two had cracked welds, and two had seals intact.

Corrective Action

The plant purchased a set of new R2 ring segments from a third-party manufacturer and had them installed. The entire R3 vane and blade rows were replaced as well. Downstream deflection of the R3 vanes plus several damaged airfoils suggested that row replacement was the prudent decision. At least 15 R3 blades had to be scrapped. Eight R4 blades also were scrapped, other R4 blades blended, and the row resequenced for installation.  R1 turbi ne di sk cracki ng was covered in two user presentations.

Cracks were identified on one machine at each blade location. They were found during a rotor inspection after approximately 5000 equivalent starts and 47,500 equivalent baseload hours (Fig 4). The unit had been cycling daily and performing loadThe 501F and 501G Users Groups co-located for the fourth consecutive year in 2010. The partnership works well and is a win/win/win for the users, third-party equipment and services providers, and Siemens Energy Inc, Orlando, the OEM for both engines. Technical user-only sessions are combined or separate depending on the subject matter; members of both groups come together for meals, social events, and the vendor fair. Luncheon presentation. Tim te.Riele, PSM’s (Jupiter, Fla) VP R&D engineering, and Mark Bissonnette, the company’s VP commercial operations, gave 501F owner/operators several reasons to consider the thirdparty supplier a viable alternative to the OEM for new hot-gas-path parts, repair of existing components, outage management activities, and long-term service agreements. te.

Riele reviewed PSM’s products and services for the 501FD, illustrating the company’s success using photos taken during a recent HGP inspection that showed parts in excellent condition after 25,000 fired hours. First-stage turbine blades were removed for refurbishment, while the second- and third-stage blades were reinstalled. Transition pieces were the next topic. te.Riele told his luncheon audience that PSM’s design had been fully validated and stressed its operational flexibility and favorable life-cycle cost. He reported that more than 40 sets of PSM TPs were installed in the 501F fleet (65 sets by the end of 2010), a significant percentage of the nominal 230 gas turbines in operation.

Stated maintenance interval for the TPs is 24,000 hours/900 equivalent starts; expected life is 72,000 hours/900 ES.The R&D executive also reviewed his company’s experience with an extended-interval combustion liner in commercial service and its automatic, continuous combustion tuning product, which is designed to eliminate manual seasonal tuning. A review of the company’s Jupiter facilities closed out te.Riele’s portion of the presentation. He discussed the F-class reconditioning facility opened in spring 2009 and now in full commercial operation. It is capable of performing all refurbishment processes onsite, including: chemical stripping, brazing, laser tip welding, EDM hole drilling, and HVOF/APS and DVC coatings. The one-stop shop was said to offer advantages in quality control and in repair cycle time. 501F, G users come together for vendor fair, other activities COMBINED CYCLE JOURNAL, Third Quarter 2010 157501F users groupfollowing duty. Siemens suggested (1) light blending of all indications to remove the minimum material to assess crack depth; (2) blending in steps to assure cracks are eliminated with a minimum of metal being removed; and (3) using generous radaii during the blending operation; no sharp corners or edges (Fig 5). Magnetic particle testing was recommended to assure cracks are removed. Documentation supported by photos was urged.  c c j