Pump shaft failure 5 • High-energy piping 10 • Weld repair 13
ENERGY-TECH A WoodwardBizMedia Publication
NOVEMBER 2015
www.energy-tech.com
Dedicated to the Engineering, Operations & Maintenance of Electric Power Plants In Association with the ASME Power Division
HARNESS THE POWER
OF MANUFACTURING INNOVATION
RENTECH engineers build unmatched power and performance into every boiler we deliver. Our 80-acre manufacturing facility—the industry’s most technologically advanced—includes heavy bay and light bay areas with direct access to rail, cross-country trucking routes and shipping facilities. We master every detail to deliver elemental power for clients worldwide. Take an expanded tour of our facilities today at www.rentechboilers.com/facilities. HARNESS THE POWER WITH RENTECH.
HEAT RECOVERY STEAM GENERATORS WASTE HEAT BOILERS FIRED PACKAGED WATERTUBE BOILERS SPECIALTY BOILERS
WWW.RENTECHBOILERS.COM
ENERGYT ECH P.O. Box 388 • Dubuque, IA 52004-0388 800.977.0474 • Fax: 563.588.3848 Email: sales@WoodwardBizMedia.com
Energy-Tech (ISSN# 2330-0191) is published quarterly in print and digital format by WoodwardBizMedia, a division of Woodward Communications, Inc. WoodwardBizMedia assumes no responsibility for inaccuracies, errors or advertising content. Entire contents © 2015 WoodwardBizMedia. All rights reserved; reproduction in whole or in part without permission is prohibited.
FEATURES
5
Why pump shaft failures happen
10
Developing an effective high-energy piping program
By Heinz P. Bloch, Energy-Tech contributor
By John L. Arnold, P.E., Niantic Bay Engineering, LLC
COLUMNS
13
Regulations Compliance
Improved weld repair options for Grade 91 steel By
John Siefert and Jonathan Parker, Electric Power Research Institute
Printed in the U.S.A. Group Publisher Karen Ruden – kruden@WoodwardBizMedia.com General Manager Randy Rodgers – randy.rodgers@woodwardbizmedia.com Managing Editor Andrea Hauser – ahauser@WoodwardBizMedia.com Editorial Board (editorial@WoodwardBizMedia.com) Bill Moore – Director, Technical Service, National Electric Coil Ram Madugula – Executive Vice President, Power Engineers Collaborative, LLC Kuda Mutama – Engineering Manager, TS Power Plant Tina Toburen – T2ES Inc. Editorial views expressed within do not necessarily reflect those of Energy-Tech magazine or WoodwardBizMedia. Advertising Sales Executives Joan Gross – jgross@WoodwardBizMedia.com Graphic Artist Eric Faramus - eric.faramus@woodwardbizmedia.com Address Correction Postmaster: Send address correction to: Energy-Tech, P.O. Box 388, Dubuque, IA 52004-0388 Subscription Information Energy-Tech is mailed free to all qualified requesters. To subscribe, go to www.energy-tech.com or contact Linda Flannery at circulation@WoodwardBizMedia.com Media Information For media kits, contact Energy-Tech at 800.977.0474, www.energy-tech.com or sales@WoodwardBizMedia.com. Editorial Submission Send press releases to: Editorial Dept., Energy-Tech, P.O. Box 388, Dubuque, IA 52004-0388 Ph 563.588.3857 • Fax 563.588.3848 email: editorial@WoodwardBizMedia.com. Advertising Submission Send advertising submissions to: Energy-Tech, 801 Bluff Street, Dubuque, Iowa 52001 E-mail: ETart@WoodwardBizMedia.com.
17
Maintenance Matters
Operating process considerations in IBMACT compliance By Bryan J. Eskra, Neil B. Childress and John S. Coons, Energy-Tech contributors
45
Machine Doctor
Catastrophic centrifugal compressor failure during startup By Patrick J. Smith, Energy-Tech contributor
ASME FEATURE
21
Hydroelectric generator-motor brake dust collection: Boundary condition selection for flow modeling of a dilute-phase pneumatic conveying system By Devon A. Washington, James B. Lewis and Robert T. Gilmore; Consumers Energy
INDUSTRY NOTES
4 30 51
Editor’s Note and Calendar 2015-2016 INNOVATION GUIDE Advertisers’ Index
ON THE WEB Have you seen Energy-Tech’s weekly newsletter yet? If not, be sure to sign up at www.energy-tech.com for the latest technical articles, business news and products in the industry.
A division of Woodward Communications, Inc.
November 2015
ENERGY-TECH.com
3
EDITOR’S NOTE
2016 plans in place Weekly newsletters, quarterly magazines and continuing webinars part of Energy-Tech’s new format
Welcome to our first quarterly print issue of EnergyTech magazine! We hope you enjoy this thicker, condensed version of our regular November issue, combining the technical articles you enjoy with the seasonal information you need. Case in point, turn to page 30 for the 2015/2016 Innovation Guide section – a great resource for your purchasing and plant service needs. The past few months have been pretty busy in our office as we’ve revamped our content, format and scheduling to better meet our readers’ needs in the growing digital market. We are busy planning into 2016 for our weekly newsletter, quarterly print issues in February, May, August and November, and our webinar courses, which are continuing to draw new presenters and attendees. Our weekly newsletter is sent out every Tuesday and contains a variety of technical article and columns, as well as the latest in industry news and product and service announcements. If you aren’t receiving the newsletter, please sign up at www.energy-tech.com. It’s a great weekly brief with information you’ll want to know. If your company would like to contribute to the newsletter, please feel free to contact me at editorial@woodwardbizmedia.com. Our quarterly print publications will be a one-stop review of articles sent out in the newsletter, as well as unique pieces found only in the issue. This is the tried and true Energy-Tech you know, and we’ll also have a digital version available on our website if you need to email it to anyone. Finally, our webinar schedule is filling up with topics you’ll want to learn more about and contributors who are subject-matter experts. All of Energy-Tech’s webinar contributors have the specialties and experience needed for them to answer for almost any question that is asked. Our goal is that attendees are able to finish the webinar courses and immediately begin applying what they’ve learned in the plant. If you haven’t signed up for an Energy-Tech webinar course, I encourage you to do so. If you or your company are interested in presenting, please let me know, again by emailing editorial@woodwardbizmedia.com. The coming year will be full of learning opportunities – I hope you’ll join us for them. Thanks for reading!
CALENDAR Nov. 4-5, 2015 Generator Users Group Las Vegas, Nev. www.genusers.org Nov. 10, 2015 FREE Webinar: Maintenance Practices for Balance of Plant Heat Exchangers www.energy-tech.com/heatexchanger Nov. 18-20, 2015 Gas and Steam Turbine Reliability Chicago, Ill. www.energy-tech.com/chicago2015 Nov. 30-Dec. 4, 2015 Advanced Vibration Control (AVC) Houston, Texas www.vi-institute.org Dec. 2-3, 2015 ETU Webinar: Understanding Zero Liquid Discharge Design & Operation www.energy-tech.com/zld Dec. 8-10, 2015 Power-Gen International Las Vegas, Nev. www.power-gen.com Feb. 16-18, 2016 ETU Webinar: The Secrets to Executing a Successful Turbine-Generator Outage www.energy-tech.com/outage March 9-10, 2016 ETU Webinar: Condenser Performance Essentials www.energy-tech.com/condenseressentials Submit your events by emailing editorial@woodwardbizmedia.com.
Andrea Hauser
4 ENERGY-TECH.com
November 2015
FEATURES
Why pump shaft failures happen By Heinz P. Bloch, Energy-Tech contributor
Technical publications thrive on questions from reliability engineers. These questions tend to inform editors and readers about a prevailing level of knowledge. Also, the questions often reflect training-related issues confronting industry. In any event, finding answers might require practical knowledge and editors of trade and professional publications often must match-up answer seekers with answer providers. Next, and to the extent possible, editors fold the resulting discourse into presentations or articles of interest to a wider spectrum of readers. This is one of these articles.
pump to freewheel in reverse due to back flow. However, I have found no documentation that supports or explains this failure mode. In conversations with various pump and field service technicians, it has been suggested that when a pump is started while spinning in reverse, the starting torque exceeds the shaft strength and catastrophic shaft failure occurs. But this explanation is counter to my understanding of electric motor starting torque.”
We were recently asked to provide guidance as a reader considered the possible causes of catastrophic pump shaft and impeller failures at his plant.
Our initial reply highlighted first what our reader, of course, knew: There are many cheap pumps and a few well-designed, more expensive pumps. When there was still an abundance of common sense (decades ago, perhaps), a wise man wrote that we always get what we pay for. Of course that is still true today and it applies to entire machines, their component parts, services, employees, contractors, educators, consultants, etc.
“In the course of my work as a Pump and Vibration Specialist,” the reader said, “I have encountered a number of such failures. One root cause of such failures that has been suggested is a defective check valve, which allows the process
Impellers and reverse rotation
Figure 1. Screw-on (dead-end threaded) impeller hub.(2)
November 2015 ENERGY-TECH.com
5
FEATURES
Figure 2. Can-type duct burner.
Back to the point: User experts Ed Nelson and John Dufour(1) noted that nearly all impeller thread arrangements (left hand vs. right hand) for single-stage end-suction pumps are such that the impeller fit gets tighter if the pump shaft rotates in the as-designed direction. Conversely, the impeller gets loose (or spins off the shaft) if the pump shaft is rotated in the opposite, or unintended, direction of rotation. Impellers installed with close-fitting keys (Figure 2, left representation) properly mated to the shaft will not spin-off in case of inadvertent reverse rotation. Properly designed keyed fits make it nearly impossible for an impeller to come off in the event of High Pressure a malfunctioning check valve causing Silencers reverse pump rotation. Simple yet effective diffuser But pumps are occa
silencing Suitable for high pressure, high temperature steam and gas Compact size and weight Non Clogging
Minimum supporting requirement
Model D800 Silencer
CU Services LLC
725 Parkview Cir, Elk Grove, IL 60007 Ph 847-439-2303 rcronfel@cuservices.net
www.cuservices.net
6 ENERGY-TECH.com
sionally running in the wrong direction and, if they do, the reasons are quite easy to find. Pump and steam turbine discharge check valves have been known to leak. Metal distortion, seat erosion and hinge friction issues can occur over time. Auto-start or standby equipment is more vulnerable because block valves are deliberately left open. In another scenario, an uninformed pump installer might decide to test for motor direction of rotation after the driver is
already coupled up to the pump shaft. That’s a risky way to verify direction of rotation which, of course, should have been checked before coupling the driving to the driven shaft.Yet, someone might have decided “to save time” by installing the motor and pump in the as-shipped (generally mounted on a base plate and coupled to an electric motor) condition. In that case, the chances of a non-keyed impeller coming off are - of course - 50 percent. The damage potential is then several orders of magnitude greater than the hoped-for savings in time.
Know the impeller fastening method No pump manufacturer has a universal impeller securing method suitable for all pump sizes and service environments. In fact, the fastening method is not usually shown on the manufacturer’s standard drawings. Also, relatively few user-purchasers include process pumps in thorough MQA, which stands for upfront machinery quality assessment. (3) Some impellers are fastened to shafts by standard acorn nuts or similar components, which the pump manufacturer buys in bulk quantities from a cost-competitive supplier. Wanting to save money upfront, some users join pump manufacturers by purchasing parts from the lowest-cost sub-vendor or third-party supplier. That’s why a good pump specification usually contains a clause requiring pump cross-section views and parts lists, which the purchaser reviews during the bid evaluation process. The commercial parts a pump manufacturer obtains from third parties must be identified in exact detail. The purpose is not a secret: Years later, an equipment owner-operator might have cause to buy replacement parts (“buy-out parts”) directly from its respective manufacturers or from entities that produce superior, upgraded, components. Fasteners can be another source of problems. Hardness and metallurgy must be observed, which brings us back to MQA. Usually, an impeller spins off only if it is not properly secured. But even a keyed impeller fit jeopardizes reliability if the key is loosely fitted. And, whatever their size and speed, pump impellers secured by castellated nuts or tab washers must retain impellers in a manner that does not allow them to come off while operating in any direction. That’s why we should examNovember 2015
FEATURES
Figure 3. Force vectors (arrows) indicate how a bending load acts on the pump shaft and how the magnitude and direction of this force changes at low flow (left image) vs. flow at design throughput conditions (right image).
ine drawings before we purchase; we also should know how parts or machines work before we buy parts. While this does not mean that one needs 50 years of experience to buy a $10,000 pumps, it does mean that, in the interest of reliability and safety, one must ask lots of relevant questions before buying plant assets. The majority of superior pump designs use keys to secure impellers. A good key fit is a “snug fit,” which means that
hand-fitting is generally advantageous.(2) The more vulnerable, sharp-cornered keyways should be avoided. Half-keys are often superior to full keys. Keyways with generous bottom fillet radii and so-called “sled runner geometry” have low stress concentration and a more desirable (higher) shaft factor of safety. Well-designed shaft ends also have a generous fillet radius at the shaft shoulder (see Figure 4). As strength considerations prompt us to maximize the various radii, their contours must not interfere with the mating radius at the bearing inner ring.Verification takes time and is time well spent.
Shaft deflection induces fatigue failures Hydraulic forces act on pump shafts; the magnitude of these forces determines shaft deflection. Shaft diameter, hardness, metallurgy, fillet radius at shaft shoulder and distance to the nearest bearing also influences how much the shaft will deflect. Shaft deflection is greater when centrifugal pumps operate at throughputs below design point or in excess of design point. Because the hydraulic force action (Figure 3) is of unequal magni-
Figure 4. Burner runner distortions from condensate. November 2015 ENERGY-TECH.com
7
FEATURES
Figure 5. Sharp corners and edges negatively affect a machine’s factor of safety.
tude and the shaft rotates, reverse bending will take place and fatigue failures are possible if the design is marginal. Examining the fracture surface and performing a simple stress calculation will give focus to weaknesses and available remedies. Possible risk reduction steps will present themselves, and future failures will be less likely when we thoughtfully select one or more experience-based upgrade options.
Motor torque and shaft stresses For the record: The starting torque of many motors is as high as 7x the full “normal” running torque. Agreed, discharge check valves rarely leak to the point of allowing substantial reverse flow. But “lean and mean” plants don’t always install these check valves – and if they do, they sometimes forget to include these valves in their preventive maintenance scheduling. In any event, a pump reliability and/or failure analysis review should include the piping and all systems in the pumping loop. Pumps, con-
8 ENERGY-TECH.com
trols, valve piping and other elements mutually interact and all must be considered.
All mechanical parts failures attributable to “FRETT” Through diligent training and reading we learn about “FRETT.” We come to accept that any and all mechanical parts can fail only due to one or more of the four cause categories: Force, Reactive Environment, Time and Temperature – “FRETT.” So because a pump shaft is a mechanical part it can only fail due to “FRETT.” An excessive reverse bending force will exist if the shaft is too slender, if its allowable bending moment or twist-inducing torque input is exceeded, if its metallurgy is not suitable for the fluid environment, if it has been in service for an abnormally long time, or if it was operated at an excessively high temperature. The reader who expressed his opinion about shaft strength and motor torque would have to examine shaft shoulder radii (fillet radius dimension) and the November 2015
FEATURES resulting stress intensification factors, see Figure 4. He would eliminate some of the FRETT causes, perhaps T for Time and T for Temperature. It might be evident to the reader that no Reactive Environment (”RE”) existed in the failed shaft system and his investigative efforts for finding the root causes of the shaft failure might come back to “F” = Force. Examination of motor starting torques may indeed show that starting torques can reach 7x normal running torque. Applying an inrush current while a shaft system spins in reverse can cause shaft breakage. In the reader’s repeat failure example, it also is possible that several seemingly small deviations combined. One can easily get away with one or even two deviations, but one rarely gets away with four or five. And what does this tell us as we ponder that, next to an electric motor, a pump is the simplest machine used by modern industry? Say a pump typically has 40 parts and yet fails relatively often. An aircraft jet engine has more than 7,000 parts and fails rarely. Why? We believe the jet engine and aircraft manufacturers strive for perfection; they disallow every known deviation. In contrast, pump engineers strive for low cost because that’s what the pump purchaser often seems to prefer over pump reliability. But top manufacturers and good engineers know that normalization of deviance can cause disasters. Their quest to find root causes of failure and not tolerating known deviances requires training and discipline, strict adherence to checklists and procedures, and allocating the time needed to do things right. In this instance we were not given enough information to accurately determine (from behind our desk) why the reader’s pump shafts failed. We can only vouch for the greatly increased probability that a few seemingly minor deviations from best practice combine, and together these deviations cause trouble. Their collective safety factors will vanish, impellers come off and shafts break. There will never be a good substitute for following procedures and uncovering what happened in this instance. Replacing parts and re-starting the rebuilt machine without addressing and eliminating the true root cause will set owners up for repeat failures. Finding root causes of failure and implementing sound remedial steps is the common sense course of action. That’s exactly what aircraft jet engine manufacturers do, and with great success. From our response, the reader will have inferred that any and all verbal hints at what may have caused impellers to spin off or shafts to fail must be supported by factual observations and evidence. There will always be a cause-and-effect relationship and it should be our task to uncover this relationship. For the benefit of the reader asking the original question, numerous texts show motor torque curves and explain why starting torques and inrush currents can differ greatly from normal operating torques and currents. Check valve action and condition may indeed be relevant. Impeller attachment is always important. Finally, pump shafts have safety factors that range from none to considerable. Safety factors are affected by shaft stresses and
high stresses can exist in shafts with discontinuities such as steps, keyways, etc. Radiused corners (Figure 5) will reduce stress intensification in keyways; these and other upgrades can be found in sturdy machinery and are readily duplicated by diligent reviewers. We hoped that our response prompted the original reader to expand their horizons, and start by considering better specifications. They should become familiar with keys or half-keys, keyways and how these blend back into the shaft with a “sled runner contour.” Failure risk can be affected by fillet radii, stress intensification factors and the many other well documented contributors to safe pump design and pump failure avoidance.✸
References 1. Dufour, J. W. and Nelson, W.E., “Centrifugal Pump Sourcebook,” (1992) McGraw-Hill, New York, NY 2. Bloch, H. P., “Pump Wisdom: Problem Solving for Operators and Specialists”, (2011) John Wiley & Sons, Hoboken, NJ 3. Bloch, H. P. and Budris, A. R., “Pump User’s Handbook: Life Extension”, 4th Edition (2014), The Fairmont Press, Lilburn, GA
Heinz P. Bloch lives in Westminster, Colo. His professional career began in 1962 and included long-term assignments as Exxon Chemical’s regional machinery specialist for the U.S. He has authored more than 600 publications, among them 19 comprehensive books on practical machinery management, failure analysis, failure avoidance, compressors, steam turbines, pumps, oil-mist lubrication and practical lubrication for industry. He holds bachelor’s and master’s degrees in mechanical engineering, is an ASME Life Fellow and maintains registration as a professional engineer in New Jersey and Texas. You may contact him by emailing editorial@woodwardbizmedia.com.
Are Shaft Currents Destroying Your Machinery? Failure to properly ground rotating equipment can result in expensive bearing, seal, & gear damage. SOHRE TURBOMACHINERY® INC.
128 Main Street, P.O. Box 1099 Monson Massachusetts, USA 01057-1099 November 2015 ENERGY-TECH.com 9 PH: 413.267.0590 • 800.207.2195 • FX: 413.267.0592 tsohre@sohreturbo.com • www.sohreturbo.com
FEATURES
Developing an effective high-energy piping program By John L. Arnold, P.E., Niantic Bay Engineering, LLC
High-energy piping systems are critical to the operation of a power generating plant. A failure in these systems can be costly in terms of both personnel safety and equipment damage. As such, it is common practice to routinely examine high energy piping systems as well as large boiler components and other critical pieces of power plant equipment on a relatively frequent basis. Jurisdictional agencies and/or insurance carriers often require these examinations, and guidance is provided in both the ASME B31.1 “Power Piping” code and in the National Board of Boiler and Pressure Vessel Inspector’s “National Board Inspection Code” (NBIC). Indeed in 2007, B31.1 implemented a requirement that power plants have an active program to evaluate Covered Piping Systems. Covered piping systems (CPS) include NPS 4 and larger main steam, hot reheat steam, cold reheat steam, and boiler feedwater piping systems. In addition, CPS includes NPS 4 and larger piping in other systems that operate above 750°F (400°C) or above 1,025 psi (7,100 kPa). CPS isn’t limited to those systems, and Expansion joint solutions other piping systems and turnkey services for can be included in power generation the program if the utility determines that the system is hazardous based on an engineering evaluation. While the ASME B31.1 code and the NBIC provide a general list of items to be covered in such a program, what makes for an effective High Energy Piping assessment program? • • • • • • •
Crossover Piping & Ducting Exhaust Systems Gas & Steam Turbines ASME Code Heat Exchangers HRSG Boiler Penetration Seals Refurbished Expansion Joints Complete Turnkey Solutions
EagleBurgmann KE Inc. Tel: +1 (619) 562 6083 ejsales@us.eagleburgmann.com www.eagleburgmann-ej.com
10 ENERGY-TECH.com
A good program should: • Clearly identify personnel responsibilities and reporting structure • Contain an up-to-date inven-
tory of welds and components Specify how welds and components are to be selected (or prioritized) for assessment • Identify damage mechanisms of concern for the various systems • Specify appropriate examination methods for specific damage mechanisms using industry standards, such as ASME PCC-3 “Inspection Planning Using Risk-Based Methods” • Delineate a clear path on the methods for evaluating any found conditions (fabrication defects, service damage and/ or material degradation), including guidance on the use of industry standards such as API 579-1/ASME FFS-1 2007, “Fitness for Service” • Provide specific details on the examination techniques and analysis methods for evaluating serviceability
Program format Most programs include numerous procedural documents to create the program. These documents, or procedures, should not be “off the shelf ” but customized to meet the specific needs of the plant. They should be crafted to fit within the existing plant procedures that exist for personnel safety, equipment maintenance and unit operations. For example, an overarching procedure may be written to provide guidance on the roles of different plant personnel and the use of outside experts and vendors. Guidance might be provided on incorporating outage-specific examinations into the electronic scheduling system, vendor selection practices and include flow charts summarizing the program, such as shown in Figure 1. Specific procedures should then be written to cover the evaluation of specific weld types (girth welds), different materials (carbon steels, low alloy steels or creep strength enhanced ferritic steels), or to address specific damage mechanisms (e.g. flow accelerated corrosion). The documents should specify the nondestructive examination techniques and required personnel certifications and qualifications. Procedures also are appropriate to address serviceability assessment methods, such as the use of fracture mechanics or material degradation modeling. To fulfill the requirements of B31.1, the program also needs to address piping supports and restrains. Specific procedures are commonly created to address these examinations, and often include examples of data reports, similar to those provided in B31.1 Nonmandatory Appendix V, “Recommended Practice for Operation, Maintenance, and Modification of Power Piping Systems.”
November 2015
FEATURES Examination methods Specified examination methods should vary to reflect the different service conditions and materials, and match the anticipated damage mechanism(s). For example, piping systems subject to elevated temperatures should be evaluated using examination methods capable of detecting creep damage, and systems susceptible to FAC should be examined for wall thinning.
active damage mechanism), the program should include surface examinations such as wet fluorescent magnetic particle testing and volumetric examinations using linear phased array ultrasonic methods. Test methods and procedures should be qualified as capable of detecting sub-surface (volumetric) service-induced damage due to creep, with a detectable threshold of at least micro-fissuring, if not high density creep cavitation.
For creep strength enhanced ferritic steels, Applying one set of examination methods such as Grade 91, hardness testing and for all CPS situations is not effective. The other supplemental metallurgical testing John Arnold’s 4-hour program should be careful to apply proven should be included in the program, with webinar course, technologies to detect the manifestations the understanding that currently no nonRisk-Based Inspection of possible damage. The use of less sensitive destructive test method is capable of confor High Energy Piping methods can result in unanticipated failures, firming “proper” creep rupture strength for is available at while using advanced methods for more Grade 91 materials. Instead, the common www.energy-tech.com basic issues can be an unnecessary expense. currently available methods, hardness testGuidance for the selection of examination ing and field metallography via replication, methods is provided in ASME PCC-3, are only capable of detecting evidence Nonmandatory Appendix C, “Table of Inspection/Monitoring of mal-heat treated material. Under specific but realistic conMethods.” ditions, a mal-heat treated section of Grade 91 with poor creep-rupture strength might exhibit acceptable levels of hardWhile specific methods and techniques will vary depending on ness and exhibit a tempered martensitic microstructure. operating conditions, for piping systems operating in the creep regime (i.e. at elevated temperatures where creep rupture is an
For lower temperature steam piping systems, the examinations should include surface examinations such as magnetic particle testing for ferromagnetic materials and volumetric examinations intended to detect planar defects, such as internal thermal fatigue cracking.
Weld prioritization A typical high-pressure steam piping system in a 2-on-1 combined cycle plant might contain 125 girth welds and 50 nozzle connections. Selecting which welds to examine during a specific outage can be difficult. Schedule and budget constraints are real, and weld selection needs to be technically justifiable. Examination costs in themselves are not insignificant, but what is sometimes lost is that the costs associated with preparing for those examinations (scaffolding, insulation removal/replacement and surface preparation) can be 10x greater. Given the financial and schedule limitations of a typical outage, it is crucial that the examinations be optimized for the best use the available resources. As such, it is important to understand all the information already collected, since the easiest way to waste money is to re-examine something innocuous after a short interval. There are numerous methods available for prioritizing examination locations within a given piping system. The most common ranking methods are: Figure 1. Typical High Energy Piping Program process flowchart
November 2015 ENERGY-TECH.com
11
FEATURES Risk analysis is a method of ranking based on the probability of an event and the consequence of that event. As detailed in ASME PCC-3, this approach can be very effective in prioritizing weld examination locations for high-energy piping programs. The analyses can be relatively simplistic (incorporating calculated applied stress values and man-pass frequency counts) or complex to include material degradation modeling, multiple degradation mechanism failures, real-time instrumentation and replacement power costs. Similarly, the scales for ranking the likelihood and consequence can be qualitative (e.g. A-E or Low-Medium-High) or quantitative with actual probabilities for failure and specific dollar values for consequence. For most high-energy piping system programs, the more simplistic models, with semi-quantitative measurements are sufficient for initial prioritization.
Figure 2. Typical High Energy Piping risk matrix
• Applied stress • Location (i.e. man-pass frequency) • Risk
12 ENERGY-TECH.com
While the specific method for ranking will varybased on the operating philosophy of the plant or utility, when developing an outage-specific workscope it is important that the locations be selected based on specific needs. Common examples include:
Using either a graphical method, as shown in Figure 2, or by tabulating the product of the probability and consequence values, prioritization is straightforward. One immediate benefit of the risk approach is that the scope of examinations can be easily determined based on the local risk culture. Furthermore, it is often found that the high risk welds or components are not equally dispersed through the population. In other words, in a population of 100 girth welds, there may be only six welds in the highest risk category. Depending on risk tolerance, this may result in an evaluation of a smaller population of welds, but a more effective assessment project.
Previous examination of this location (or weld) revealed evidence of service damage. Subsequent serviceability analyses determined that this outage was an appropriate time to check for damage progression. This location is a high stress/manpass frequency/risk location, and has not been examined previously.
Recent changes in the ASME B31.1 Power Piping code have increased the industry awareness for high-energy piping (or Covered Piping System) assessment programs. These programs can be a time- and cost-effective way to manage the critical piping components when they are properly developed and implemented. Personnel also can customize the program around existing plant operating structure and philosophy to create meaningful assessment projects. Use risk analysis methods to optimize outage scopes for both budget and schedule needs and rely on documented examination procedures to gather all necessary information to perform a meaningful serviceability evaluation.✸
Summary
John L. Arnold, P.E., is a principal engineer at Niantic Bay Engineering, LLC.You may contact him by emailing editorial@woodwardbizmedia.com. November 2015
REGULATIONS COMPLIANCE
Improved weld repair options for Grade 91 steel By John Siefert and Jonathan Parker, Electric Power Research Institute
The Electric Power Research Institute is leading a multi-national research project to evaluate the integrity of alternative options for repair of Grade 91 steel components. This research is necessary to overcome problems with conventional repair methods. The challenges with traditional repair procedures are a direct consequence of difficulties in controlling post-weld heat treatment (PWHT) in the field within the currently mandated temperature range. Research achievements have identified significant benefits from performing cold weld repair (i.e., welding with no PWHT) and weld repair followed by PWHT at a temperature significantly below the current minimum. The EPRI studies have focused on two key component types, namely: repair options for thin-section materials (i.e., tubing) and repair options for thick-section components (i.e., balanceof-plant applications such as headers, piping, stub to header, etc.). This research has led to the world’s first approved weld repair method for Grade 91 steel that does not mandate PWHT (Welding Method 6 for tube-to-tube weld repairs, which has been incorporated into the National Board Inspection Code [NBIC] Part 3 Repairs and Alterations). Furthermore, the investigations have ignited discussion within the American Society of Mechanical Engineers Boiler and Pressure Vessel (ASME B&PV) Code regarding reduction of the current minimum allowable PWHT of 1,350°F (730°C) to 1,250°F (675°C) for new construction of Grade 91 steel weldments.
Grade 91 steel Power plant applications of creep strength enhanced ferritic (CSEF) steels have increased greatly during the last two decades. One of the most widely utilized CSEF steels is a 9 percent chromium steel widely known in industry as T91, P91 or Grade 91. Since the early 1990s, Grade 91 steel has been used in fossil power steam boilers, heat-recovery steam generators (HRSGs) and piping systems. The alloy has enhanced properties, including high creep-rupture strength and fracture toughness, compared to traditional low-alloy steels. Higher strength makes Grade 91 attractive because of the potential for higher operating temperatures – up to 1,100°F (593°C) – and lower wall thickness, with excellent toughness significantly reducing the risk of fast fracture. Grade 91 is, therefore, suitable for use as a retrofit material in conventional subcritical power plants, for plants that will operate in cyclic mode, and as a building material for advanced supercritical plants and HRSGs. Service experience has shown a significant need for on-site weld repairs to Grade 91 steel components. Rather than simply rely on the use of procedures qualified for new construction for these repairs, research was conducted to establish the technology to support a well-engineered weld repair. These new approaches offer rapid, nonconventional welding procedures for minimum cost replacement and repair.
Critical issues related to weld repair of Grade 91 steel
Figure 1 Damage tolerance in Weld 6C-1, a partial weld repair (50 percent depth), made with EPRI P87 filler metal and controlled fill welding technique.
A number of issues have driven the need to investigate alternative options for weld repair of Grade 91 steel: Many current repairs are performed using rules for new construction.Yet no relevant research indicates that these repair methods are technically appropriate for in-service components. Field PWHT maintained within the allowable range of 1,350°F to 1,450°F (730°C to 790°C) has proven to be very challenging. Much evidence shows that poor heat treatment practice leads to significant over-temperature exposure. Research also indicates that any excursion above the allowable maximum dramatically reduces the long-term creep strength of Grade 91 steel and its weldments. Many in-service failures of Grade 91 steel components have been documented. Explanations include poor design, poor operation, bad construction practices, metallurgical risk factors, and other causes. Regardless of the root cause for each documented failure, the number of documented failures highlights
November 2015 ENERGY-TECH.com
13
REGULATIONS COMPLIANCE the need for validation of weld repair options that can be used for the range of Grade 91 steel components in service. The technical details for “best practice” regarding welding of low-alloy bainitic steels should not be applied directly to welding of tempered martensitic steel. Thus, repair techniques established for “conventional” low-alloy steels are not directly relevant for repairs on Grade 91 steels.
Thin-section weld repair: Method 6 For weld repair of thin-section Grade 91 steel, EPRI research investigated the use of a nickel base (Ni-base) filler metal (EPRI P87) using a cold weld repair approach. This research culminated in the acceptance by the National Inspection Code Part 3 of Welding Method 6. In tests to date, no reports have been made of a marked reduction in performance or inability to qualify repair welding procedures using Ni-base filler metals for T91 steel. Indeed, this type of repair has been shown to comply with the criteria in ASME B&PV Code Section IX. With regard to qualification of the welding procedure, the test data showed that for the Gas Tungsten Arc Welding (GTAW) process, the selection of filler material was not an important consideration. However, for welds made using the Shielded Metal Arc Welding (SMAW) process, the use of filler metal
14 ENERGY-TECH.com
EPRI P87 could introduce difficulties in passing side bend tests. These problems were a direct consequence of the weldability challenges using this electrode. It is currently recommended that for qualification of welds made using the SMAW process, ENiCrFe-2 or ENiCrFe-3 be used as the filler. With regard to high-temperature creep performance, the use of an Ni-base filler does not appear to reduce the creep performance of the weldment. Differences in the location of creep damage have been recorded. Several limitations have been linked to the use of Welding Method 6, and are highlighted in the National Board Inspection Code Part 3 Repairs and Alterations language. The limitations include tubing 125 mm (5”) or less in diameter and 12.7 mm (0.50”) or less in wall thickness. Repairs can also be performed only within a location internal to the boiler or HRSG setting. Successful adoption of Welding Method 6 has prompted the need for additional research to provide additional flexibility in the code’s language. The direction of this research is being guided by discussions with end-users who are implementing these innovative repair procedures into their corporate welding programs. Two initiatives that are the subject of ongoing research include relaxation of the maximum interpass temperature from 400°F (200°C) to 550°F (290°C), and addition of a ferritic filler metal into the allowable filler metal repair options.
November 2015
REGULATIONS COMPLIANCE using EPRI P87 filler metal and a controlled fill technique (see Figure 1).
Thick-section weld repair: Three weld procedures The investigation into well-engineered repairs for thick-section components was undertaken in several phases. In the first phase, researchers ranked the repair performance of 10 unique weld repair procedures applied to Grade 91 parent steel in two different conditions. In the second and third phases, the three best option weld repair methods were applied to an ex-service Grade 91 header. The options included: • E9015-B9 Filler Metal + Controlled Fill + Low PWHT (675°C, 1,250°F/2 hours) • E8015-B8 Filler Metal + Controlled Fill (No PWHT) • Ni-base (EPRI P87) Filler Metal + Controlled Fill (No PWHT) The research sought to: (1) examine if the condition of parent material modified performance, (2) evaluate options for the removal of damage and (3) establish the important considerations regarding the geometry of the excavation (such as the bevel angle). The investigation resulted in the fabrication of 16 different welds, more than 150,000 hours of creep testing, detailed metallographic examination of each weld after manufacture, and evaluation of each specimen after testing.
Because of the need for data, continued interaction and guidance based on relevant testing and evaluation, a new series of investigations has already been initiated. The goal of this follow-on work in Phase 4 is to apply the developed welding techniques to a wider range of materials and component scenarios. Provided the National Board Inspection Code Part 3 Repairs and Alterations approves the proposed welding supplement by the July 2016 meeting, the process for the acceptance of alternative welding methods for thick-section weld repair is expected to take six years. Alternative weld repair options for Grade 91 steel have already been applied in some cases. Recently, the world’s first documented repair using the guidance in the Best Practice Guideline was applied by the Tennessee Valley Authority (TVA) in its Southaven Combined Cycle Plant. In this through-section weld repair, a 152 mm O.D. (6”) x 22 mm (0.864”) wall Grade 91 manual dump valve was welded to the main steam line using ER80S-B8 and E8015-B8 filler metals without PWHT. At the first outage, this repair weld was inspected using conventional ultrasonic non-destructive evaluation, and no defects were documented. It has now operated at ~1,065°F (575°C) for several thousand hours.
The results of this research were summarized in an EPRI report entitled Best Practice Guideline for Well-Engineered Weld Repair of Grade 91 Steel. This report contains 20 sections with specific guidance on weld fabrication. In addition, nine appendices provide practical supporting technical evidence that validates the recommendations in the document. Prior to publication, the report underwent a critical review and assessment by end-users, industry experts and participants in codes and standards. One factor highlighted in the Best Practice Guidelines is the importance of the excavation geometry. While strength is one consideration for any weld repair, less emphasis has traditionally been placed on damage tolerance. Examinations of the extent of excavation have shown that repair welds in Grade 91 steel made with an optimized excavation are more damage-tolerant and less susceptible to rapid (potentially catastrophic) failure than traditional geometries. Thus, a well-engineered weld repair has the ability to not only exhibit an acceptable life but, more importantly, to provide a safer solution as compared to the traditional fabrication methods. This effect is shown in an actual test, made in a partial repair weld
Non-Intrusive Flow Measurements in the HRSG Industry t Highly accurate and reliable flow measurement up to 750 °F t No process stops for installation t Virtually maintenance free t Decreased downtimes and forced outages
The Ideal Solution for: t Phase detection – steam or water in the HRSG during startup t Controlling drain valves during heavy cycling t Measurement of auxiliary liquidsystems – water treatment, cooling tower flows, natural gas www.flexim.com · salesus@flexim.com
FLEXIM AMERICAS Corporation · Toll free: 1 888 852 74 73
November 2015 ENERGY-TECH.com
15
REGULATIONS COMPLIANCE Conclusions EPRI is currently engaged with all stakeholders involved with the electric supply industry (including the codes and standards committees, insurance regulators and expert working groups) to gain acceptance of the proposed repair welding procedures and techniques for Grade 91 steel. The benefits from well-engineered repairs are driving a series of follow-on studies to provide the necessary technology transfer to these various groups. Three welding procedures have been successfully developed for the weld repair of Grade 91 steel piping and components. Test results have demonstrated that these procedures achieve crossweld creep lives above the minimum of the required scatter band for a range of parent material conditions and under representative creep conditions. The well-controlled welding procedures tested in research to date offer significant advantages over the conventional repair procedures. The reduction in the allowable PWHT temperature to 1,250°F (675°C), or the elimination of PWHT altogether, has an immediate tangible benefit in alleviating many of the problems associated with field PWHT. Lastly, with proper well-engineered approaches, the design and application of weld repairs in Grade 91 steel will not only achieve performance similar to the weld it is replacing, but more importantly can introduce damage tolerance, an attribute that is not inherent to conventional weldments (new or repair) in Grade 91 steel.
Note: Initial crack formed in the Grade 91 heat-affected zone (HAZ) associated with the repair weld but was forced to propagate through the more creep-strong and creep-ductile Grade 91 base material. Because the step is removed from the original weld that was left in the bottom of the simulated repair, the crack is not allowed to continue to propagate along the intolerant fracture path in the Grade 91 HAZ associated with the original girth weld.✸ Resources 1. Best Practice Guideline for Well-Engineered Weld Repair of Grade 91 Steel. EPRI. Palo Alto, CA: 2014. 3002003833. 2. Alternative Well-Engineered Weld Repair Options for Grade 91 Steel: An Executive Summary of Results from 2010 to 2014. EPRI. Palo Alto, CA: May 2015. 3002006403. 3. TVA Applies an Alternative Well-Engineered Weld Repair Method for Grade 91 Steel. EPRI. Palo Alto, CA: 2014. 3002006394. 4. Guidelines and Specifications for High-Reliability Fossil Power Plants, 2nd Edition: Best Practice Guideline for Manufacturing and Construction of Grade 91 Steel Components. EPRI. Palo Alto, CA: 2015. 3002006390. 5. A Perspective on the Selection of Preheat, Interpass, and Post-weld Cool Temperatures Using Grade 91 Steel as an Example. EPRI. Palo Alto, CA: 2015. 3002005351. 6. A Well-Engineered Approach for Establishing the Minimum Allowable Post Weld Heat Treatment for Power Generation Applications of Grade 91 Steel. EPRI. Palo Alto, CA: 2015. 3002005350.
John Siefert is a senior technical leader supporting EPRI’s Fossil Materials and Repair Program. Siefert previously worked for Babcock & Wilcox and has experience in welding research that includes dissimilar metal welding; development of processes for advanced ferritic, austenitic, and nickel-based alloys; post-weld heat-treatment; waterwall fabrication; and procedure qualifications. You may contact him by emailing editorial@woodwardbizmedia.com. Jonathan Parker is a technical executive in EPRI’s Boiler Life and Availability Program. He provides expert support for projects associated with understanding the factors affecting damage in critical components. Previous employment includes positions with Swansea University (UK), the Central Electricity Generating Board (UK), Ontario Hydro (Canada), Replication Technology Inc., Failure Analysis Associates, and Structural Integrity Associates Inc. (USA). You may contact him by emailing editorial@woodwardbizmedia. com.
16 ENERGY-TECH.com
November 2015
MAINTENANCE MATTERS
Operating process considerations in IBMACT compliance By Bryan J Eskra, Neil B. Childress, John S. Coons, Energy-Tech contributors
Industry is well along the path of attaining IBMACT compliance via the execution of a number of compliance strategies. These strategies range from modifications of current operation parameters – i.e. boiler tuning, additional combustion controls for both solid and natural gas fueled boilers – to more heavily capital-based solutions involving additional back-end control equipment, boiler modifications to permit natural gas firing or direct replacement of the existing boilers. This article will focus on installations that chose to stay with their current solid fuel and determined to move forward through the addition of control equipment for acid gas, mercury and particulate control. In these cases, coal is the primary fuel at sites where limited access to firm natural gas at a reasonable cost occurs. These are the facilities that have seen cheap natural gas disappear and believe that in the foreseeable future the natural gas industry will not have the infrastructure and supply to meet their existing and long-term needs. Accordingly, their IBMACT plans rely on coal and its continued supply. Oftentimes the user does not recognize that today’s coal will not necessarily be the same as tomorrow’s and that the implementation plan needs to reflect that process parameters for both the combustion of the fuel and the control equipment that will change with time. Without this recognition of the potential for change, the result will potentially be operating limitations in regard to capacity or non-compliance. In the North Central region, coal was traditionally used for boiler fuel, with large facilities moving from stoker boilers to the adaptation of pulverized or cyclone furnaces. With ready access to coal from the Illinois Basin, which was suitable for use within a cyclone furnace, many paper mills – particularly in Wisconsin – adapted single- and multi-burner cyclone furnaces instead of pulverized coal. The cyclone boiler eliminates the onsite fuel preparation and accepts coal directly into the combustion chamber. Beginning in the 1980s with the implementation of sulfur dioxide regulations, fuel blending of lower sulfur coals, i.e. Powder River Basin, with traditional Illinois supplies to yield lower SO2 emission rates occurred. A mixture of both regional coals is necessary to maintain acceptable ash fusion temperatures for proper cyclone operation. Additional economic market influences, including reduced cost of natural gas, lower overall demand in industry for coal, increased coal export, and the diminishing number of coal suppliers, also affected industry costs. Furthermore, this changing availability of solid fuels will impact the performance of the existing particulate control equipment, which IBMACT control technology to select and the efficiency of the sorbents used. The assessment of existing equipment must include a review of what fuel is presently fired and what future fuels might be available to ensure a successful outcome.
Figure 1. Hydrate Injection Test
Figure 2. Hydrate Injection Test
Figure 3. Trona Injection Test, Boiler 4
Table 1 shows the existing potential fuel blends utilized at a number of facilities for which IBMACT compliance projects are currently underway. Note that in addition to the previously mentioned Illinois – Powder River blends, pet coke, tire-derived fuel and wood also have been added to make the plant fuel “cocktail” both useable within the cyclone furnace and economical for the facility. Table 2 shows that for the fuel blends the expected gas flow rates and uncontrolled emission parameters vary widely. Consider that an increase in any emission rate from a specific fuel will result in a corresponding increase in sorbent usage,
November 2015 ENERGY-TECH.com
17
MAINTENANCE MATTERS
Krytox™Fluorinated Lubricants Krytox™ Oils and Greases. These high-performance fluorinated lubricants are derivatives of Teflon® and offer the following advantages: Chemically inert. Wide temperature range (-103°F to 800°F). Compatible with plastics, rubber, ceramics, & metals. Nonflammable. Insoluable in common solvents. No silicones or hydrocarbons. Krytox™ is applied to gearboxes, dampers, ductwork valves, steam valves, gaskets, seals, compressors, bearings, boilers, pumps, and Turbine Auxiliary systems. For more information and sample call 800.992.2424 or 203.743.4447. Channel Partner Since 1991
m
TM
s
California - Illinois - Connecticut - Canada e-mail: supportET@mschem.com www.miller-stephenson.com Krytox ™ is a trademark of The Chemours Company FC, LLC
18 ENERGY-TECH.com
the designer and the owner are faced with the reality that any IBMACT solution has limitations that will ultimately impact the cost of the fuel and the cost of compliance. Recognition of process parameters influenced by the selection of the fuel is requisite. It is very easy to want to weight average the fuel analysis during the design process. However, this cannot occur because the average fuel analysis is not the fuel being burned. The fuel being burned happens to be four different fuels and weight averaging them will distort the emissions with no way to determine the distortion. Table 3 shows the four fuels, the weighted November 2015
MAINTENANCE MATTERS
average fuel and the results of the combustion calculations using each fuel. The calculations are based on the same boiler steam flow or heat output being produced by the four fuels and the weighted average fuel. Based on the fuel analysis for each fuel, a boiler efficiency and fuel consumption is calculated. Assuming complete conversion of the fuel sulfur to SO2, the amount of theoretical SO2 is calculated. As the combined result column shows, the total SO2 is more than 7 percent less than if the weighted average fuel were used. Now look at the ash production, the weighted average is less than the combined result. Similarly, as additional fuels and combinations are considered, the calculations would be repeated. Once a design or most probable case is established, the appropriate IBMACT compliance technology can be selected. After defining the fuels and their respective emission rates, the degree of reduction is determined through comparison of the regulated emission and the uncontrolled rates. This information provides the basis for the selection of the control technology most suited for the source. For the emission species in question, for boilers 1-3 only acid gas and Hg emissions are of concern. The current SO2 emission requirement for the facility does not require any reduction at this time. Available IBMACT control technologies are wet scrubbing, dry scrubbing (both spray drying and circulating fluid bed) and dry sorbent injection (DSI). Because of the relatively low emission rates and reduction levels required, dry sorbent injection was selected for the control technology. Accordingly, a sorbent that is effective for the reduction of halogen emissions to the IBMACT compliance level is required. Sorbents utilized for dry sorbent injection applications for acid gas control are hydrated lime, trona and sodium bicarbonate. Table 4 shows for the various combinations of operating conditions the level of sorbent usage and the corresponding byproducts that must now be collected by the particulate control device.You will note that the sorbent usage for trona and sodium bicarbonate are significantly greater than for hydrated lime. This can be attributed to the preferential capture of SO2 by the sodium compounds. The SO2 concentration level must be reduced to a comparable reactivity level of the halogens prior to the capture of the halogen compounds of interest. Conversely if SO2 is the species of interest, trona or sodium
bicarbonate and similar sodium based compounds would be the preferable sorbents to utilize. To demonstrate the phenomenon described previously, Figures 1-3 show the relative performance of the three sorbents (lime (Calcium based)), sodium bicarbonate (sodium based), and trona (sodium based)) when injected into the fuel gas stream of Boiler 4. As the sodium sorbents are injected, the Cl concentration remains fairly level until a significant level of SO2 is captured. Conversely, for hydrated lime a significant amount of sorbent is required prior to seeing a reduction in SO2 with concurrent reductions of Cl. It is only in the presence of water vapor, for example, in a scrubber or spray dryer, do calcium-based sorbents readily react with SO2. The Boiler 4 facility requires a nominal amount of sulfur dioxide reduction for compliance and sodium bicarbonate injection was selected as the cost effective solution. However when selecting sodium-based compounds for compliance the owner must take into account that resultant byproducts, (sodium sulfite and sodium chloride) become part of the ash products. These sodium products are soluble compounds and might need to be disposed in lined landfills, incorporating adequate provisions for the protection of ground and surface water. Disposal costs are potentially significant and should be considered in the ultimate selection of technology. Calcium-based byproducts in general have lower solubility and are disposed with flyash with landfill design requirements com-
Applications: • Steam pressure vessels • Hot water heaters • Demineralizers • Steam humidifiers • Water purifiers • Refrigeration units • Liquid treatment vessels
• Compressed air tanks • Filtering units • Dryer cans in paper mills • Water towers • Water softeners • Deaerators • Make-up tanks
The steam boiler market makes extreme demands on gaskets; Topog-E® Series 2000 gaskets are specifically designed and fabricated to provide the superior performance users of Topog-E® gaskets have come to expect – but at higher operating pressures and temperatures.
1224 North Utica | Tulsa, OK 74110 T: 918-587-6649 | E: info@topog-e.com W: www.topog-e.com
November 2015 ENERGY-TECH.com
19
MAINTENANCE MATTERS parable to that of flyash. Furthermore the resultant ash–calcium byproduct mix is potentially saleable as concrete admixture. Powdered Activated Carbon (PAC) is the traditional injection material for the control of mercury emissions, and in a DSI configuration is injected downstream of the acid gas injection point. The actual point is dependent upon the selected sorbent reaction rate. The acid gas sorbent must have sufficient time to react with acid gas. This distance is accordingly a function of the reaction rate of the sorbent at the flue gas temperature and the velocity of the flue gas. For example, if the reaction rate requires 3 seconds to accomplish the necessary HCl reduction
20 ENERGY-TECH.com
and the gas velocity is 40 ft/sec, the PAC injection point will be 120’ downstream. Note the PAC needs time to adsorb the Hg on its surface, and this results in additional ductwork length prior to the particulate matter control device. If insufficient time exists and distance is unavailable compared to injection of PAC, the acid gas sorbent is often needed to overcome the deficiency. The last processes impacted are the particulate matter control device and the fly ash handling system. Using DSI technology, these systems are now receiving the acid gas sorbent byproducts, unused sorbent and the PAC sorbent, in addition to the flyash generated by combustion. The ash handling system often was originally sized to operate a limited number of the day, generally once a shift to empty the hoppers. The owner has the option to run the system longer in duration with the knowledge that the online storage capacity in the collection device hoppers is greatly reduced. If, upon examination, it is determined that the storage capacity or conveying capacity is undersized, a new ash handling system might be required. The owner should not overlook the sizing of the ash loading silo as well, since the durations between unloading cycles also have been reduced and additional capacity is required. The use of sorbents have an impact on the particle control device as well. Heavier particulate matter loadings will impact the cleaning cycles and rapping cycles for fabric filters and electrostatic precipitators respectively. Increased fabric filter pressure drop is to be expected for existing fabric filters, which might impact induced draft fan capacity if it cannot provide the required gas pressure to pass through the fabric filter. For electrostatic precipitators each sorbent has a different impact. Calcium-based sorbents will increase resistivity while sodium sorbents and PAC will decrease the bulk resistivity. Precipitator controls will need optimization and monitoring to maintain pm emission levels. An evaluation of the long-term impact and costs utilizing existing fans and particulate control technologies is encouraged. IBMACT compliance decisions should be based upon a full understanding of what fuels the facility will fire, the operational scenarios under which the facility operates, recognition that specific sorbents have specific purposes and react preferentially, and a plan for the systems downstream of the treatment areas adversely affected.✸
November 2015
ASME FEATURE
Hydroelectric generator-motor brake dust collection: Boundary condition selection for flow modeling of a dilute-phase pneumatic conveying system
By Devon A. Washington, James B. Lewis and Robert T. Gilmore; Consumers Energy
Introduction Pumped storage plants generate electricity by taking advantage of the potential between two reservoirs at different elevations. During off-peak hours, the pump-turbine is used to pump water from a lower reservoir to an upper reservoir; in pumping mode the generator functions as a motor. During peak demand, the water stored in the upper reservoir is allowed to pass through the pump-turbine generating electricity.
Depending on how a unit is dispatched, this cycle may be repeated on a daily basis. [1] Vertical hydro-generators utilize mechanical braking systems to stop the unit’s rotation. The braking process is triggered automatically by speed switches in the generator’s control system. The typical target setpoint range to initiate braking is 20-50 percent of the unit’s nominal operating speed. Most systems are designed to bring the unit to a complete stop within 3-5 minutes. [2] The brake ring and brake shoes are most commonly located in the generator housing; therefore, a key maintenance concern for hydro-generators is the accumulation of brake dust in the interior. Brake dust deposition on the windings can occur, adversely affecting cooling and electrical isolation. [3] To alleviate this issue, many hydro-generators are equipped with brake dust collection systems. The objective of this study is to examine the proper selection of boundary conditions for designing a robust brake dust collection system.
Pneumatic conveying System types and descriptions Pneumatic conveying can be divided into two major categories: dilute-phase and dense-phase. Dilute-phase conveying is characterized by high velocity, low pressure and low solids-to-air ratio. Conversely, densephase conveying is defined by low velocity, high pressure and high solids-to-air ratio. Dilute-phase conveying is defined by suspension flow, where the particles are suspended and transported. Transport by dense-phase conveying can occur in two modes: bed flow or pulsatile flow. [4] In general, dilute systems consist of five major components: (1) conveying line, (2) air mover, (3) feeder, (4) collector and (5) controls. These systems can be subdivided into Figure 1. Plan view of hydro generator brake dust collection system. November 2015 | ASME Power Division Special Section
ENERGY-TECH.com
21
ASME FEATURE three primary groups based on the method of conveying: (1) pressure system, (2) vacuum system and (3) pressure and vacuum system. [5] The brake dust collection system considered in this study is a vacuum system. System design parameters When designing a pneumatic conveying system, there are several parameters that need to be considered. Some of the key parameters include: material properties, particle size, material flow rate, air flow rate, pressure drop, pipe diameter, saltation velocity, and pickup velocity. As is the case with most complex systems, several of these parameters are implicitly related. [4] To ensure that suspension flow is maintained throughout the system, it is essential that the proper airstream velocity is achieved at each point along the conveying line. Therefore, determining the correct saltation and pickup velocities is a critical part of the design process. Saltation velocity is defined as the velocity at which particulate begins to settle out of the flow. Pickup velocity is the velocity required to suspend particulate at rest. These definitions are illustrated in Figures 2a and 2b. [5] There are several correlations for determining saltation velocity; the most common is Rizk, which is expressed as [5],
Figure 2. (A) Saltation velocity, (B) Pickup velocity
(1)
(A) (2) (B) The first term on the left-hand side of Eq. 1 is the solids loading ratio, which is defined as the ratio of the mass flow rate (kg/s) of the solid being transported to the mass flow rate (kg/s) of the gas used to convey the solid (Eq. 3). Gas velocity is: ug (m/s). The gravitation constant is, g = 9.81 m/s; pipe diameter is, D (m).
I
(3)
Equations 2a and 2b are parameters, where dp (mm) is the particle diameter. Using Eqs. Figure 3. Pipe network diameters
22 ENERGY-TECH.com
ASME Power Division Special Section | November 2015
ASME FEATURE
Figure 4. Fan performance curve
Figure 5. Filter pressure drop characteristics
1-3 and solving for the gas velocity, the saltation velocity is expressed as:
data. [6] For very dilute systems (µ d 0.5), Zenz predicted that pickup velocity (Eq. 5) could be as much as 2.5x greater than the saltation velocity. [7]
(4)
There are also several expressions for predicting pickup velocity, all of which yield varying results when compared to empirical
(5) This is a conservative approach for designing a dilute conveying system and the method adopted for this study. Since the brake
Are Shaft Currents Destroying Your Machinery?
Failure to properly ground rotating equipment can result in expensive bearing, seal, & gear damage.
Sohre Turbomachinery® Inc. designs and manufactures shaft grounding brushes and related systems. Thousands of Sohre shaft grounding brushes have been installed and are being used in many kinds of rotating equipment (steam turbines, gas turbines, compressors, pumps, propeller shafts, reduction gears etc.). Over ten thousand Sohre Turbomachinery® brushes are installed, protecting Figure 7. Brake dust 500x magnification machinery all over the world. These brushes can also be used as part of a shaft current monitoring program. have been installed to replace brushes initially supplied by the turbomachinery OEM. In many cases, Sohre Turbomachinery® brushes are specified as standard equipment on new machinery.
SOHRE TURBOMACHINERY® INC.
128 Main Street, P.O. Box 1099 Monson Massachusetts, USA 01057-1099 PH: 413-267-0590 • FX: 413-267-0592 • info@sohreturbo.com • www.sohreturbo.com Figure 6. System superficial velocities: (A) equal flow BC; (B) equal pressure BC November 2015 | ASME Power Division Special Section
ENERGY-TECH.com
23
ASME FEATURE
Figure 6. System superficial velocities: (A) equal flow BC; (B) equal pressure BC
Have you visited our new website? We’ve got a new look! Featuring an updated interface with improved search features, faster access to topics and updated news and features, events calendar and much, much more!
ENERGY-TECH.com 24 ENERGY-TECH.com
ASME Power Division Special Section | November 2015
ASME FEATURE
Figure 8. Inlet pressure distribution required to sustain equal flow
dust collection system for the hydro-generator is only operated at most 10 minutes once or twice a day, and improved system maintainability is the ultimate goal, a conservative approach is warranted. For other processes and operating conditions a different approach might be more suitable. [8]
Analysis The goal here is to determine, for a given system configuration, what inlet boundary condition should be invoked when using flow modeling software to calculate the superficial air velocity at each section of the system. The superficial air velocity is the gas velocity disregarding the particulate. Once calculated, the superficial velocities are compared to the computed saltation velocities and pickup velocities for a given solids mass flow rate, pipe diameter, particle diameter and air density. Pneumatic model A one-dimensional, steady state flow model of the conveying system was developed using PIPENET. [9] The two types of inlet boundary conditions (BC) considered were equal flow and equal pressure. The model includes all relevant piping details: diameters, lengths, fittings, elevations and roughness. Figures 1 and 3 show the general arrangement of the pipe network; for proprietary reasons the pipe lengths and other geometric dimensions are not provided. For the purposes of comparing and contrasting the results of the model, knowledge of the pipe diameters is sufficient.
In addition to detailed piping information, PIPENET also is capable of modeling fans and filtering elements. This is accomplished by inputting the fan performance curve and the filter element’s pressure drop characteristics (Figure 4 and 5). From Figures 1 and 3 it can be seen that the piping network is annular in shape and has 16 inlets, one for each brake jack. The inlets are located in the interior of the generator housing, directly adjacent to the brake pads. The brake dust is funneled into the inlets of the pipe network via a shroud. Figure 1 depicts the brake dust collector. The filter and fan are housed within the unit. The filtered air discharges to atmosphere. The fan curve (Figure 4) indicates that the best efficiency point is at approximately 60 m3/min and 2.6 kpa. For a flow rate of 60 m3/min, the pressure drop across the filter is approximately 1.5 kpa (Figure 5). Table 1 provides a summary of the air properties and BCs used for both models.
Particle analysis To calculate the saltation and pickup velocities, the mean particle diameter is required. Figure 7 is an image of a brake dust sample taken with a scanning electron microscope (SEM) at 500x magnification. Based on an analysis of the particle-size distribution, it was determined that the average particle diameter was approximately 40 Âľm. The mass flow rate of brake dust is 0.0022 kg/s per brake. Results and discussion Table 2 shows for the equal flow BC, both the saltation and pickup velocity criteria are satisfied. However, for the equal
Figure 7. Brake dust 500x magnification
November 2015 | ASME Power Division Special Section
ENERGY-TECH.com
25
ASME FEATURE
Figure 9. System superficial velocities for equal pressure BC, optimized case
pressure BC the velocities at the outer extremities of the header are less than the pickup velocity. The solids loadings are also itemized in Table 2. The direct proportionality between saltation velocity and pickup velocity (Eq. 5) holds for very dilute systems, that is, systems with solids loadings less than 0.5. [7] This is the case for all sections of the conveying system (Table 2). The superficial velocity distributions are illustrated in Figures 6a and 6b. The seminal question here is which BC most accurately reflects the physical system. To assess whether or not equal flow is a realistic BC, the pressure at each inlet necessary to sustain equal flow was calculated, shown in Figure 8. Due to symmetry, the inlet pressure distribution was only calculated for half of the header. Figure 8 demonstrates that, in order to achieve equal flow at each inlet, the pressure must vary as shown. There are no control devices at the inlets to regulate pressure. Additionally, air pressure measurements taken in the generator interior, under nominal operating conditions, show that the pressure at the inlets is approximately 1,065 Pa.
26 ENERGY-TECH.com
Figure 10. Pipe network diameters, optimized case
The characteristic dimensions of the generator interior are much, much larger than the inlet pipe diameter. Therefore, assuming the pressure distribution in the generator interior is uniform is a reasonable modeling assumption. Using pickup velocity as the design criterion, the application of equal pressure as a BC shows the outer sections of the system are potentially at risk of particulate buildup (Figure 6b). To mitigate this and achieve sufficient velocities throughout the system, the collection header pipe diameters need to be strategically reduced to achieve an optimum system velocity distribution. Figure 9 shows the results of such an exercise. The corresponding pipe sizes are given in Figure 10. Comparing the velocities in Figure 9 to Figure 6b, it is clear that by optimizing the collection header pipe sizes the velocities in the outer extremities of the system are increased considerably.
Conclusion The results of this study demonstrate that the superficial velocity distribution for the system, generated when equal flow is
ASME Power Division Special Section | November 2015
ASME FEATURE applied as a BC, is drastically different from the equal pressure BC. A careful assessment of the system and its surroundings should be undertaken before selecting BCs for a model. Based on the analysis conducted here and pressure measurements taken in the generator, the equal pressure BC more accurately reflects the conditions in the generator interior. Designing robust dilute conveying systems for hydro-generators is an important part of protecting sensitive components to reduce maintenance and improve reliability.
Acknowledgements The authors would like to acknowledge operating services, engineering services and lab services management and engineering staff, as well as technical and engineering staff from the hydroelectric section of generation and operations.✸ Nomenclature Latin symbols D Pipe diameter Dp Particle diameter G Gravity M&g Gas mass flow rate M&s Solids mass flow rate Ug Gas velocity Upick Pickup velocity Usalt Saltation velocity
Table 1 – Air properties and coundary conditions Air Properties Temperature
40oC
Density
1.127 kg/m3
Boundary Conditions Inlet flow per brake 3.5 m3/min Inlet pressure
1.065 kPa (gauge)
Outlet pressure
0.000 kPa (gauge)
µ Pg
Solids loading Gas density
References [1] Harza Engineering Company, “Pumped-Storage Planning and Evaluation Guide,” EPRI, Palo Alto, CA, 1990. [2] BC Hydro International Ltd., “Hydro Life Extension Modernization Guide – Volume 3: Electromechanical Equipment,” EPRI, Palo Alto, CA, 2001. [3] IEEE-SA Standards Board, IEEE Std 492: Guide for Operation and Maintenance of Hydro-Generators, New York, NY: IEEE, 1999(R2011).
Greek symbols Δ Rizk correlation parameter K Rizk correlation parameter
Table 2 – Velocity and solids loading summary Diameter* (mm)
Superficial Velocity# (m/s)
Superficial Velocity^ (m/s)
Saltation Velocity (m/s)
Pickup Velocity (m/s)
Solids Loading (#)
80
12.2
3.8
2.6
6.4
0.142
100
14.2
6.1
3.0
7.4
0.157
150(1)
9.8
5.5
3.1
7.7
0.101
150(2)
13.1
8.7
3.3
8.4
0.125
150(3)
16.3
12.7
3.6
9.0
0.146
200(1)
11.2
10.4
3.5
8.8
0.100
200(2)
13.1
13.9
3.7
9.2
0.111
250
9.6
11.7
3.7
9.1
0.082
300
14.4
17.5
4.3
10.7
0.097
*The 50 mm entrance pipes, from the brake jack to the header, are not the primary focus of this study (1), (2), (3) indicates header pipes of the same diameter with increasing mass flow rates (see Fig. 3). # Equal flow BC ^ Equal pressure BC
November 2015 | ASME Power Division Special Section
ENERGY-TECH.com
27
ASME FEATURE [4] D. Mills, Pneumatic Conveying Design Guide, Second Edition, Burlington, MA: Elsevier Butterworth-Heinemann, 2004. [5] W. C.Yang, Handbook of Fluidization and Fluid-Particle Systems, New York, NY: Marcel Dekker, Inc., 2003. [6] L. Gomes and A. A. Mesquita, “On the Prediction of Pickup and Saltation Velocities in Pneumatic Conveying,” Brazilian Journal of Chemical Engineering,Vol. 31, No. 01, pp. 35-46, 2014.
[7] F. J. Cabrejos and G. E. Klinzing, “Incipient Motion of Solid Particles in Horizontal Pneumatic Conveying,” Powder Technology,Vol. 72, pp. 51-61, 1992. [8] E. Rabinovich and H. Kalman, “Threshold Velocities of Particle-Fluid Flows in Horizontal Pipes and Ducts: Literature review,” Chemical Engineering,Vol. 27, pp. 215-239, 2011. [9] Sunrise Systems Ltd., PIPENET Vision - Version 1.7, Cambridge, UK: Sunrise Systems Ltd., 2014.
Fuel Gas Conditioning
Celebrating 50+ Years
Fuel Gas Conditioning Systems for all Turbines
713.460.5200
www.gaumer.com 28 ENERGY-TECH.com
sales@gaumer.com ASME Power Division Special Section | November 2015
BOILERS
SELL•RENT•LEASE
Why Wabash.
SPEED. Our competitors measure a turnaround in hours and days. We measure it in minutes. INVENTORY. We keep one of the world’s largest, newest and most reliable inventories of high-quality equipment. SMARTS. Our people have the experience and technical knowhow to craft just the right solution. MARKET KNOWLEDGE. We stay on top of evolving environmental issues, escalating fuel costs and other challenges so that we can
continue designing solutions to meet today’s requirements. DEPENDABILITY. Because we’re responsive, fair and steadfast, our customers count on us for more than the right equipment. Our job is not complete until you’re generating steam. COMPASSION. We know you have a lot on your mind, but we can ease part of the burden. Steam generation equipment is what we thrive on, so you can count on us to be there for you.
Trailer-Mounted Saturated Boilers
Every Wabash trailer-mounted saturated boiler is easy to operate, cost effective and environmentally compliant. We’re always ready to move at a moment’s notice. Our entire fleet of rental boiler packages includes simple control schemes, low NOx emissions and high fuel efficiency. • 10,000 to 85,000 PPH steam capacity • 100-725 psig operating pressure • Natural gas, #2 fuel oil, and/or constant value refinery gas Optional equipment: • Economizer packages • Associated ancillary equipment
• Mobile SCR systems (5-9 ppm NOx) • Trailer and skid mounted water treatment systems
Trailer-Mounted Superheated Boilers
Discover the reason refineries, utilities, petrochemical, chemical, paper and other major processing industries have counted on us for many years. With one call, you can access the nation’s largest fleet of medium- and high-pressure, superheated boilers. • 30,000 to 75,000 PPH steam capacity • 350 psig design with operating ranges from 125 to 325 psig • 750 psig design with operating ranges from 350 to 675 psig • Maximum superheat temperature of 750 °F Optional equipment: • Economizer packages • Associated ancillary equipment
• Mobile SCR systems (5-9 ppm NOx) • Trailer and skid mounted water treatment systems
Packaged Watertube Boilers
Wabash also offers large package boiler systems, ready to ship by rail. • Capacity from 100,000 to 250,000 PPH • Saturated and superheated • Pressures as high as 1,025 psig • Maximum superheat temperatures of 900 °F
And More at the Ready
Whatever you need, Wabash has the inventory, the expertise and the commitment to deliver the right high-quality equipment faster than all the rest. By land, air and sea, our inventory is ready to go. And so are we. So give us a call today at (800) 704-2002. Count on us!
Wabash Power Equipment Company 444 Carpenter Avenue Wheeling, IL 60090 Phone: (847) 541-5600 Toll Free: (800) 704-2002 Fax: (847) 541-1279 Email: info@wabashpower.com Web: www.wabashpower.com
Innovation Guide - Business Directory
9955 International Blvd. •Cincinnati, Ohio 45246 Phone: 513.247.5465 Fax: 513.247.5462 www.atcontrols.com
Manual and Automated Quarter Turn Valves Complete Valve and Damper Automation Steam Service Steam is an invisible gas unless condensed in cooler air. Steam has many industrial uses like heating and cooling applications and because of its expanding nature, for generating power. Forms of steam include saturated, superheated and supercritical. Caution needs to be used when selecting valves for steam service to assure the application temperature and pressure are met with the right valve body and valve trim materials. Saturated Steam: Steam that exists as both liquid water and water vapor. This form of steam occurs when the steam is at its boiling point at a particular pressure and temperature. The temperature and pressure of the steam determines the amount of each phase of water. A table showing saturated steam properties is shown on the next page. Superheated Steam: Water heated above its boiling point that exists only as water vapor. This occurs when saturated steam is held at a constant pressure and heated to a temperature above its boiling point. The water bubbles have been removed from the steam system . Super Critical Steam: Steam that does not solely behave as a liquid or gas. This occurs around 1,049°F at 3,200 psig.
Standard Material
Please consult A-T Controls for material selections for your application. These parameters are guidelines, and customers are responsible for materials of construction and lubricants that are compatible with their steam application:
Valve Packages
Power-Seal High Performance Butterfly Valves- Sizes: 2”-24” (larger sizes available upon request), ANSI/ASME Class 150# and 300# Lug and Wafer, Blow out proof stem design. Literature Download: http://download.atcontrols.com/pdf/HPBV20141002.pdf Series FD9- 150#, 300#, 600# Direct Mount Split Body Flanged Ball Valve, Firesafe, 316SST or WCB, multiple sizes available. Literature Downloads: FD9 150#: http://download.a-tcontrols.com/pdf/FD9M20130430.pdf FD9 300#: http://download.atcontrols.com/pdf/ FD9F3M-20140403.pdf FD9 600#: http://download.atcontrols.com/pdf/ FD9F6M-20130430.pdf Series F8R- Sizes ¼”-2-1/2”, Full Port and Regular Port 1500/2000 psi WOG (by size), 316 SST or Carbon Steel Body, Threaded, Socket Weld, or Butt Weld. Literature Download: http://download.atcontrols.com/pdf/ F8RM-20130430.pdf Series M- Sizes ½”-8”, High Performance Metal Seat Ball Valve, Anti-static device, ISO 5211 Mounting Pad, Firesafe API 4th edition. Literature Download: http://download.atcontrols.com/pdf/FMX20130430.pdf
Auxiliary Stem Seal: Graphite Body: Carbon Steel, 316 SST, others Seats: PTFE (up to 400 °F), RTFE (up to 450 °F), 50/50 (up to 500 °F), Metal Seats Trim: 316 SST, 17-4 PH, Stellite
Manual and Automated Quarter Turn Valves Complete Valve and Damper Automation
30 ENERGY-TECH.com
November 2015
Industry’s most comprehensive Quarter-Turn Valve and Actuator line
• Stainless, Carbon and Alloy Ball Valves • Multi-port Ball Valves • High-Performance Butterfly Valves • Elastomer and Teflon-lined Butterfly Valves • Rack and Pinion and Heavy-Duty Scotch Yoke Pneumatic Actuators • Electric On/off , Modulating and Fail-Safe Actuators • Automation Control Accessories • V-port and Segmented Control Valves • FM Approved Safety Shut-off Valves
9955 International Boulevard Cincinnati, Ohio 45246
(513) 247-5465 FAX (513) 247-5462 e-mail: sales@atcontrols.com www.atcontrols.com
A-T Controls has the products, knowledge, and capability to handle your complete project from ¼” Ball Valves, to 48” Butterfly Valves and complete Automation products and services. Choose A-T Controls for your next project!
Innovation Guide - Business Directory
Indeck Maintains 175 Year Mission to Deliver Steam Generation Solutions Founded in 1960 as a single emergency power equipment rental company, Indeck is now a group of companies serving power producers worldwide. The Indeck Group is a total solutions provider with engineering, manufacturing, boiler sales and rentals under one roof. Key players in the Indeck Group of Companies include Indeck Keystone Energy LLC, Indeck Power Equipment Co., Indeck Boiler Corp., Indeck Energy Services and Indeck Service Co. The first of these companies, Indeck Keystone Energy is celebrating 175 years of engineering steam equipment this year. Its roots date back to the early beginnings of the industrial revolution when many prestigious brands started in Erie, Penn., including Zurn Energy, Aalborg (land-based boilers) and Keystone Energy. Indeck Keystone works closely with Indeck Power and Indeck Boiler to design, fabricate and deliver boilers and steam generation equipment to power utilities, refineries, power generators and chemical plants worldwide. Indeck Energy is a developer, owner and operator of cogeneration and independent power projects in North America; and Indeck Service focuses on servicing Indeck and Volcano boilers and boiler repair in Eastern Canada.
Indeck Designs Superheat Boilers and More
Indeck Power, the founding company of the group, has been serving utilities and plants worldwide since 1960. Indeck Power maintains a full inventory of boilers for sale, rent or lease. Indeck also conducts research to develop the most efficient equipment. Its engineers work with Indeck Boiler to design and fabricate super-efficient boilers. Recently improved highly efficient 75,000 pph superheat boilers were designed for 750 psig and 750oF operating conditions. Additionally, the new Superheat Indeck boilers are designed to take several fuel types, including natural gas #2 oil, and include manufacturer’s standard boiler trim, low NOx burner and combustion controls. Economizers and the Indeck Selective Reduction Systems (I-SCRs) are available for increased efficiency and NOx reduction. Economizers are used to reduce fuel use by recovering heat from boiler stack gases that would otherwise be lost to the environment.
Indeck Meets Customer Demand for Auxiliary Steam
In the utility sector, Indeck Power has worked with both private and public utilities to meet emergency or auxiliary boiler needs. Indeck Power has an East Coast utility client currently renting a 32 ENERGY-TECH.com
65,000 pph saturated boiler for auxiliary heat to alleviate taxing the existing system. Another major utility rents a 60,000 pph boiler for auxiliary steam while the utility is revamping existing boilers, in order to provide steam to keep the turbines warm. During severe winters a northern U.S. utility rents several Indeck boilers to compensate for excess winter steam loads, as well as providing for plant heating. With expedited services, quality boilers and a 24/7 call center, plants can rely on Indeck. The company stocks superheat and saturated boilers up to 250,000 pph that can be available for quick delivery. Indeck also has designed and built the proprietary I-SCR (Indeck Selective Catalytic Reduction System) so plants can meet the ultra-low NOx emissions required for compliance. Utilities and plants can never be too ready for unexpected power needs, so Indeck has created the I-MAP (Indeck Master Agreement Program) for its customers. This allows Indeck to have valuable information in advance of the emergency and assure smooth service at time of need.
Engineered Steam Solutions Meet Emissions and Reduce Global Warming
Indeck Keystone Energy is the technology and engineering center for the Indeck Group and focuses on custom boiler designs, waste heat recovery boilers, FCCUs, solid fuel boilers, specialty boilers, boiler upgrades and engineered boiler parts, as well as engineering studies and system retrofits. The Indeck Keystone engineers work with clients like engineering firms, EPCs, utilities, refineries and large plants to customize solutions. With more tightening of the environmental regulations, more and more utilities, campuses and municipalities are looking at combined heat and power for their energy needs. To meet this demand, Indeck Keystone designs I-HRSGs for combined cycle and cogeneration plants. The combined-cycle plant using natural gas as primary fuel is a popular choice to meet today’s power generation needs and reduce global warming. The use of I-HRSGs to recover heat from gas turbine exhaust is vital for maximum performance, higher efficiency and greater cost effectiveness.
To view the Indeck Group’s complete product and service offering visit its company sites: www.indeck.com www.indeck-keystone.com www.indeckenergy.com www.indeck-service.com November 2015
Innovation Guide - Business Directory
Indeck Group of Companies Indeck Keystone Energy LLC • Indeck Power Equipment Co. • Indeck Boiler Corp. • Indeck Energy Services Inc. (814) 464-1200 • 24-HR Parts: (800) 322-5995 • www.indeck-keystone.com • info@indeck-keystone.com
November 2015 ENERGY-TECH.com
33
Innovation Guide - Business Directory
Precision Signal Simulator from MTI Instruments • The 1510A Precision Signal Simulator/Function Generator from MTI Instruments combines high precision voltage and charge mode signal generation in a single handheld device packed with features. Designed for machinery and gas turbine maintenance, the 1510A produces accurate and precise voltage, charge and speed signals necessary for system troubleshooting, testing and calibration. This handheld 1510A can be programmed to generate two independent signals of different wave forms (SINE, SQUARE, TRIANGLE and PULSE) and different frequencies up to 100 kHz. Each output channel can be independent or synchronized with each other. A USB port allows remote control and programming of the unit.
34 ENERGY-TECH.com
November 2015
Innovation Guide - Business Directory This one of a kind function generator also includes the ability to generate keyphasor speed signals and has a variable phase control to simulate machinery imbalance conditions for testing and calibration of data acquisition systems. A unique low voltage bridge mode allows simulation of strain gauge signals. The 1510A’s charge output simulates signals from piezoelectric accelerometers. A jog function for the amplitude and voltage controls allows users to slowly vary the signal when evaluating the performance of data acquisition systems. MTI also offers several accessories, including software that allows setup and remote operation from a PC, and an assortment of cables such as BNC to BNC signal cables, single-ended and differential charge cables, to facilitate connections to your equipment. The 1510A is a tool that improves productivity and machinery availability, as well as ensuring equipment and system accuracy. From the high visibility protective boot and built in rechargeable battery to its spill-proof keypad, the 1510A is guaranteed to make signal simulation easier and more accurate than ever. •
www.mtiinstruments.com
üSimulate Speed and Sensor Signals üSweep Function üDual Channels w/ Synchronization üRechargeable Battery (up to 6 hrs. of continuous use per charge)
Contact us:
TEL: (518) 218-2550 URL: www.MTIinstruments.com EMAIL: sales@mtiinstruments.com
scan code for complete specifications
November 2015 ENERGY-TECH.com
35
Innovation Guide - Business Directory
Rotork offers extensive site-service capabilities to power plants Today’s power plants have a clear need to update existing equipment and take advantage of new technology. To answer this need, Rotork Site Services (RSS) provides an extensive array of technical service capabilities to support older plants with modern equipment as well as field services. The global RSS team consists of specially trained service technicians who can provide a high-level of expertise in diagnosing, servicing, installing, and maintaining actuators and related equipment in power plants and other process industries. They are available to work for customers on either a specific project or an on-going contractual basis. Logistically in the U.S., RSS teams are strategically located remotely to support the nation’s power industry. In addition, there are seven major Rotork service centers that can handle in-house repairs and provide back-office support. RSS USA has the physical resources to quickly deliver the highest quality service capabilities. It maintains a comprehensive inventory of parts and tools, and it has 42 service vehicles extensively outfitted with service-related equipment — vehicles carry strategic inventory for their particular customer base. Also, in various circumstances, RSS can provide service for non-Rotork products. A key component of RSS is the Rotork Client Support Program (CSP), which is designed to increase asset reliability and availability of a plant’s Rotork valve actuator and control products. The program includes predictive and planned maintenance, as well as asset management for all Rotork products. The program enables plants to reduce the cost of ownership and maintenance risks year on year. It allows end users to maximize production throughput, manage costs and concentrate on core business deliverables. Rotork’s client service program follows ISO 55000:2014 guidelines, which state, “Asset management involves balancing the costs, opportunities, and risks against desired objectives.”
A partial list of CSP features includes: · · · · · ·
Asset Management Emergency/Priority Response Predictive and Preventive Maintenance Extended Warranties Parts Management Discounts on Actuators and Parts
Currently, the field retrofit services offered by RSS are extremely popular in the power industry. Some recent examples of retrofit opportunities are replacing older actuators on existing valves and dampers as well as on manually operated equipment. The RSS team can provide onsite technical assistance, start-up services, and complete turnkey installations. Applications include modifying existing steam lines and drain lines associated with the Boiler Island. There is also a strong need to have better control near the boiler walls. It’s noteworthy that Rotork 36 ENERGY-TECH.com
Rotork Site Service personnel arrive at a power plant in North Texas.
can offer both electric and pneumatic solutions, which is important in many parts of the plant, including in the combustion air arena where precise control of dampers for air handling is crucial. Different boiler manufacturers build their equipment with infrastructures particular to their own designs, so working with an independent actuator manufacturer that can provide both electric and pneumatic options is an advantage.
Another popular service offered is pre-outage inspections. RSS technicians survey the plant and make recommendations to overhaul certain equipment on critical systems. A RSS technician at work on a power plant retrofit and Once the proposal start-up project. is reviewed, the customer’s outage team decides which services will be done and scheduling occurs. At the onset of the outage, RSS comes into the plant and removes the targeted actuators. The actuators are then sent to the nearest service center where they are overhauled on a predetermined priority basis. After service, test and full recertification, they are shipped back to the site and installed by RSS personnel. In summary, Rotork Site Services is providing a unique service addressing the needs of today’s power plants by easing the burden of maximizing production throughput and managing costs while ensuring the highest level of reliability and availability of Rotork actuators and the valves they control. Contact Rotork for additional information.
Rotork Controls, Inc. 675 Mile Crossing Blvd. Rochester, NY 14624 Phone: 585.247.2304 Email: sales@rotork.com November 2015
Enhance plant-wide performance with Rotork actuator and damper-drive solutions Rotork provides high-performance, cost-effective valve actuator and damper drive solutions throughout your entire power plant. Solutions that can help you maximize plant performance, minimize maintenance problems, and help you meet stringent safety and environmental regulations. Hundreds of different valve actuators and damper drives are required throughout a typical power plant facility. Rotork can meet all of your needs by offering motor-operated, fluid power, electro-hydraulic, and manual gear operators. Actuators and drives suited for harsh, rugged operating conditions, inside and out, servicing every size and style of valve from small process control valves to superlarge isolation valves as well as rotary, linear, or quarter-turn combustion-air and flue-gas dampers. Furthermore, the advanced technological capabilities of Rotork smart actuators can help you easily upgrade connectivity and provide a smart window to your process that includes important predictive maintenance data to help you improve productivity and efficiency as well as cut maintenance costs. Whether you are building a new plant or are currently operating a fossil-fuel, nuclear, or green-energy facility, we can help. Rotork actuators and drives are currently servicing hundreds of power plants around the world. Our more-than 50-years experience and proven expertise can help you, too. Contact us today.
IQ3 electric actuator with smart window technology
SM6000 S2 heavy-duty electric damper drive
Rotork Controls, Inc. 675 Mile Crossing Blvd. Rochester, NY 14624 phone: 585 247 2304 email: info@rotork.com
www.rotork.com
Redefining Flow Control
Type K pneumatic rotary damper drive
Innovation Guide - Business Directory
ENGINEERING STRENGTH
Engineering Strength –
in our people, knowledge and service For more than 30 years, Structural Integrity Associates has been a trusted partner to every sector of the energy industry. We’re proven in a wide variety of applications, including R&D, engineering, metallurgy, NDT, nuclear and fossil-fueled power plant support, oil and gas transmission pipeline applications, renewable energy sources, and forensic and chemical engineering support. Nearly every generating utility in the United States has relied on us. We are proud of our rich history in preventing and managing structural and mechanical failures, but we never rest on past successes. Our culture of continuous innovation and improvement inspires us to develop better solutions for structural evaluation and repairs – strategies that are less invasive and more effective and affordable.
We do it all:
· · · · ·
Structural Integrity’s engineering strength comes in many forms -- from our team of over 200 engineering and technical experts, to applying our knowledge to many power plant and pipeline assets to our 30+ years of experience. You can also look to us in the following areas for our ability to link theory and practice: • Knowledge of power plants, codes, and how things work. • Extensive experience and leadership. • High quality, hard work, and responsiveness. • Custom, integrated equipment, software and solutions.
Call us today to put our engineering strength to the test.
Scan the QR Code for more information
877-474-7693 (877-4SI-POWER) www.structint.com/energy-tech
38 ENERGY-TECH.com
Inspection and monitoring Materials evaluations Remaining life assessments Stress and failure analyses Remediation and repair support
We also take on the bigger, tougher jobs. We assist with plant license renewal, help manage aging plant assets, oversee fabrication, help schedule overhauls, develop customized inspection systems, offer ASME Code support, and provide training and expert opinions. Clients choose Structural Integrity for the Engineering Strength in our people, our knowledge and experience, and the top quality service we provide. We have offices throughout the United States and Canada, as well as affiliates in China, Korea, Spain, Switzerland and Taiwan, to better serve our global client base. We lead the industry with more than 200 industry experts and technical staff. We also have powerful strategic partnerships with other leading companies whose specialties dovetail with ours. To stay abreast of emerging issues – and help resolve them – our people stay actively involved in industry organizations, and many take on leadership roles. Our team includes some of the brightest minds in the business – and our technical know-how is matched by unparalleled customer care. When you partner with Structural Integrity, our team becomes your team. For responsive service and creative, customized strategies, turn to Structural Integrity — and expect Engineering Strength.
1-877-4SI-POWER (1-877-474-7693) www.structint.com/energy-tech
info@structint.com November 2015
Innovation Guide - Business Directory Rentech Boilers Systems continues to lead the industry – producing new, innovative boiler designs • Our boiler manufacturing experience and passion for customer service has made a significant difference to our customers, who include the largest independent power producers, refining, petrochemical and industrial companies in North America. At RENTECH, we aren’t resting on our reputation – we are continually building one!
Market leader in large-fired packaged boilers
During the past 4 years, we have supplied more large-fired packaged boilers than any other manufacturer in the North American market for units > 100,000 lb/hr in size. Our packaged boiler design has been specified time and again for critical industrial processes, turbine warm-up and auxiliary boiler applications because of its rugged design and proven reliability. A 100 percent membrane wall construction eliminates the need for refractory and enables quick start-up to achieve full steam capacity of the boiler in a fraction of the time that it takes with older designs. In addition to significantly reducing maintenance and operating costs, a water-cooled membrane wall furnace offers additional benefits in reducing emissions.
Integrated solutions for achieving lower emissions
Our approach to achieving lower emissions starts with optimization of the boiler design. Coupled with RENTECH’s knowledge of low emissions burner and catalytic reduction technologies, we are capable of supplying a system that fully complies with all performance criteria and is backed by a singlesource guarantee.
HRSGs for small- and medium-sized gas turbines
We specialize in, and are the largest supplier of, HRSGs for today’s high-efficiency gas turbines that operate in the 3-40 MW size range. Our expertise in high-fired applications incorporates full optimization of the duct-burner performance while utilizing Catalytic Oxidation and SCR for control of emissions from the entire system. • www.rentechboilers.com
Industrial Watertube Boilers/Waste Heat Boilers/ SCR Systems Design Features: • 100 percent headered membrane water wall construction • No refractory walls or seals • Fully drainable convective super-heater that eliminates the problems associated with radiant designs • Customized designs for applications requiring lowest emissions • Standard 5-year warranty on front and rear furnace walls Turnkey Capabilities: • Integrated Low NOX Burner and SCR/CO catalyst systems guaranteed to achieve less than 5 ppmvd • Installation and start-up services • Comprehensive engineering and design evaluation of other boiler systems rebuilds, upgrades and major modifications of existing boilers
November 2015 ENERGY-TECH.com
39
Innovation Guide - Business Directory
Unimar Aviation Warning Light Lowering System The Unimar Aviation Warning Light Lowering System is used to raise and lower obstruction light fixtures mounted on cokers, heaters, flares, smoke stacks and other structures in the refining and utility industries. The aviation warning light lowering system can safely raise and lower fixtures mounted up to 230’ high. All electrical contacts are copper with MIL SPEC nickel plating and 30 micro-inch gold plating over the nickel. The gold plating passes the Industrial Mixed Flowing Gas test designated to create corrosion. All gearboxes and lowering tool frames are of heavy-duty design to provide reliability, long life, and ease of operation. They incorporate solid steel heat-treated gears for maximum durability and strength. All are equipped with a special automatically actuated disc brake for better load holding ability and the prevention of the load free-wheeling. They are essential for lifting operations. Available for permanent installation or portable use indoors or outdoors for wall mounting, tower mounting or pole mounting. Each system is custom tailored to work with required load and operation of the raising and lowering specifications. In addition, lowering systems are also available for cameras and other indoor and outdoor lighting. These systems offer fast, safe
and easy maintenance of lights, cameras and other devices in high or inaccessible areas. All servicing for the appliances is done at ground level. Hazardous and time consuming high lift truck maintenance is eliminated. The efficiency of the higher mounting height need not present a problem in servicing the equipment. The use of high mounting height results in fewer appliances used. This means reduced installation costs and less power usage. This savings offsets the cost of the lowering system. Cameras, lights and other devices are lowered individually, eliminating the need to lower massive lowering units which are complicated, expensive and heavy.
structio
FA ng A
LED Ob
igh n L ti
Indus
g htin
l L tria ig
xplosio
Proof
ntr Co ols
n
E
THE ANSWER TO ALL YOUR ILLUMINATION NEEDS! 40 ENERGY-TECH.com
Unimar.com (800) 739-9169
November 2015
Innovation Guide - Business Directory FlmrEnrgyTch 1/2 pg-4CWbtch
3/5/12
2:26 PM
Page 1
A REVOLUTION IN BRUSH CHANGING FOR TURBINE-GENERATOR RELIABILITY Fulmer improves its plug-in brush holder Fulmer Company of Export, Pa., improved the design of its single pocket, cartridge style, plug-in holder, a product that offers a revolution in brush changing for turbine-generator reliability. OEM approved, Fulmer’s product is a direct replacement for the original brush holders used on GE, Westinghouse and other manufacturers’ generators. And no expensive, time-consuming rigging modification is required to install the holder, just remove the old holder, clean the rigging and install the Fulmer FC101 style holder. In fact, brushes can be removed on-line, without any service interruption. The longer brush box creates better brush support and can accommodate a 4˝ brush, greatly lengthening brush life and reducing the frequency of brush changes. Lightweight and ergonomically built, the holder also offers two styles of removable insulated handles. The “shorter” handle with flash guard protects fingers from brush shunts, while the optional, extended handle can be used for holders that are difficult to access. And a portable Brush Load Fixture enables operators to quickly and easily change brushes. Economically priced, the holder utilizes standard brushes and terminals and improves machine performance by reducing brush selectivity and improving air flow and cooling. Fulmer Company is the largest North American manufacturer of brush holders for DC machines, and a supplier to major global OEMs and aftermarket customers. OEMs include GE, Siemens, Toshiba and others. Major aftermarkets include power generation, railroad, transit, mining, steel and motor repair shops. Fulmer Company is certified to the ISO 9001:2008 standard by Det Norske Veritas.
www.fulmercompany.com
The NEW Cartridge-Style Plug-In Brush Holder It is now possible to easily and safely change brushes on live equipment! The solution the industry has long awaited is now available from the leader in brush holder technology, Fulmer Company. ■ Brushes changed on-line, without service interruption, using a simple changing fixture ■ Direct replacement for many OEM styles with no rigging modification required ■ Longer brush box to provide better brush support and allow the use of a 4” brush, increasing brush life and reducing the frequency of changes ■ Rugged, lightweight and ergonomically built ■ Removable insulated handle with flash guard
BRUSH CHANGING MADE EASY
THE FULMER WAY.
Fulmer Company A Wabtec Company 3004 Venture Court Westmoreland Industrial Park III Export, Pennsylvania 15632 Phone 724-325-7140 www.fulmercompany.com
November 2015 ENERGY-TECH.com
41
Innovation Guide - Business Directory
Borescopic visual inspection World-class image quality, overnight delivery and prices onehalf to one-third that of comparable borescopes – that’s the innovative Hawkeye® Precision Borescopes! Its newest rigid and flexible video borescopes display high-quality inspection images on a video monitor, laptop or desktop computer. The images can be saved, documented and
e-mailed. The newest addition to the Hawkeye line is a prime example, the new Hawkeye V2 Video Borescope. The new Hawkeye V2 represent the next generation of fully portable, articulating video borescopes manufactured by Gradient Lens Corporation. (wwwgradientlens.com/V2) These new scopes deliver 5x higher image quality than fiber optic borescopes and are made in the U.S. Operators can quickly and easily inspect turbine blades, combustion chambers, cooling tubes in heat exchanges, gear boxes and more, all without the need for costly and time consuming engine and system teardown. Fully portable, Hawkeye V2 Video Borescopes are 4-way articulating and come complete with video monitor and light source, all in one easy-to-use device. Hawkeye V2 Videoscopes are either 4 mm or 6 mm in diameter, and have flexible, rugged, 4-layer tungsten sheathing. They are available in lengths up to 6.0 m. Custom lengths are available upon request. For more than 20 years, Gradient Lens Corporation has designed, engineered and manufactured precision optical instruments. The company sells more industrial borescopes than any other manufacturer. Its patented endoGRINS® gradient-index lenses are built into our exclusive line of Hawkeye Precision Borescopes. Gradient Lens Corporation carries more than 80 models of rigid, flexible and video borescopes, as well as video microscopes. All are in stock and ready for overnight delivery. www.gradientlens.com or 800-536-0790
42 ENERGY-TECH.com
November 2015
Innovation Guide - Business Directory
Shaft Grounding and Contact Assemblies from Cutsforth Cutsforth’s Shaft Grounding and Shaft Contact Assemblies provide an effective way to resolve shaft voltage problems created by the rotating equipment on generators. Installation of the shaft grounding system requires little or no modification to the generator. By including Remote Meter Points, plant personnel can safely test voltage and current levels using handheld meters or oscilloscopes, and can easily determine when to replace the ground rope. Our new Shaft Contact Assembly, mounted on the shaft at the exciter end of the generator, aides in early detection of changes in voltages, including short duration transient. Taken together, the Shaft Grounding and the Shaft Contact Assemblies can facilitate root cause analysis of stray voltage on a generator shaft. The patent pending rope design helps assure ground is maintained by providing long service life and best in class rope to shaft contact. Environmental contaminants present a variety of problems; Cutsforth’s rope guide minimizes the impact of contaminants on the rope, improving performance. By incorporating the EASY Change Holder concept in the assemblies, Cutsforth continues a tradition of providing reliable mission critical products that improve generator reliability and reduce the risk of failure, without re-creating the wheel.
Shaft Grounding and Contact Assemblies • Engineered universal fit rope with durable and flexible Teflon Rope Guide • Fits horizontal shafts 8” and larger • Protects rope and shaft surface from contaminants • Isolates ropes independently to allow effective voltage metering • Rope guide funnel ensures easy and safe rope installation • Patent pending rope design • Provides best-in-class wear performance • Single universal fit mounting arm • Simplifies installation process across a wide array of generator types • Simplifies removal during major maintenance events • EASYChange ground rope holder makes rope changes simple and safe • Engineered for high heat environments (up to 200oC) • Assembly includes Remote Meter Points to safely measure shaft voltage and current • Switch ensures the path to ground is not interrupted when maintenance is performed
November 2015
Introducing Cutsforth’s powerful new Shaft Constant Monitoring System. Designed to collect, store and pass critical voltage information to plant personnel for analysis, the system provides Waveform level information that can be easily exported for in-depth analysis as required. The system supports common analog outputs, and can be configured for digital outputs to meet varied communication needs of plants. Even if not directly connected to DCS, the system provides the performance information on demand at the Touch Screen monitor and can be downloaded via a USB port at the same monitor housing. Through implementing the complete Shaft Constant Monitoring System, power producers are better positioned to avoid costly failures into the future.
Shaft Constant Monitoring System • Large LED Touch Screen Monitor for real time information display • USB port enables data download for analysis or the installa tion of upgrades and revisions • Up to 40 MHz scan rate and waveform level data of critical shaft grounding elements • Peak and Average Ground Current • Peak and Average Shaft Voltage (between the turbine and generator) • Peak and Average Shaft Voltage (outboard of the generator at the exciter location) • Ability to capture details of transient events associated with failures • Rope Alarm indicates when ground and metering ropes require replacement • Remote Meter Points enable technicians to safely take independent hand held or oscilloscope meter readings 7 Channel 4/20 mA outputs • All data points and rope status can be communicated to plant DCS systems • 100-120VAC 5A/200-240 VAC 2.5A power input
ENERGY-TECH.com
43
Innovation Guide - Business Directory A-T Controls 9955 International Blvd. Cincinnati, OH 45246 P: 513-247-5465 www.a-tcontrols.com A-T Controls designs, develops and manufactures valves, actuators and valve control products, including manual ball valves and automated ball valve packages; actuators for the automation of industrial valves; positioners for precise modulating control; electrical solenoid valves for on/off control; limit switches for end of travel position indication; and valve control accessories, including gearboxes and overrides, block and bleed valves, dribble control systems, lock-up valves, flow and speed control, dome indicators, filter/regulators and more.
Cutsforth Inc. 5160 Industrial Place, Ste 101 Ferndale, WA 98248 P: 800-290-6458 www.cutsforth.com Cutsforth focuses on products and services for brush rigging, commutators and collector rings. Products include Cutsforth’s online-removable brush holders and shaft grounding units. Services include online collector ring and commutator truing, helical groove restoration, vibration analysis and onsite consulting. Cutsforth products increase safety, reliability and lower maintenance costs
MTI Instruments Inc. 325 Washington Ave. Extension Albany, NY 12205-5505 P: 800-342-2203 www.mtiinstruments.com MTI Instruments Inc. (MTII) has been supplying precision measurement solutions for more than 50 years to industries worldwide. MTII’s products use a comprehensive array of technologies to solve real world applications, including manufacturing, automotive, commercial/military aviation and electronics. Some of the technologies we use to solve measurement applications include capacitance, fiber-optic and 1D and 2D laser sensors.
Rentech Boiler Systems Inc. 5025 East Business 20 Abilene, TX 79601 P: 325-672-3400 www.rentechboilers.com Rentech designs and manufactures high quality custom boilers in a variety of categories, including: fired packaged boilers, waste heat boilers, heat recovery steam generators, specialty boilers and emissions control systems.
Fulmer Company 3004 Venture Court Westmoreland Industrial Park III Export, PA 15632 P: 724-325-7140 www.fulmercompany.com Fulmer Company is an ISO 9001:2008 compliant manufacturer of brush holders, castings, springs and machined parts for power generation, supplying major OEMs globally with engineered designs for new and direct retrofit applications. Our improved FC-101 cartridge-style plug-in brush holder enables brush changes on-line, without service interruption, offering a revolution in turbine-generator reliability.
Gradient Lens Corp. 207 Tremont Street Rochester, New York 14608 Phone: 800-536-0790 www.gradientlens.com Gradient Lens Corp. manufacturers more than 80 models of patented Hawkeye® Rigid, Flexible and Video Borescopes. World-class image quality, overnight delivery, and prices one-half to one-third that of comparable borescopes – that’s the innovative Hawkeye Precision Borescopes! Our newest rigid and flexible video borescopes display high-quality inspection images on portable video monitors, and laptop or desktop computers.
Indeck Power Equipment Co. 1111 Willis Avenue Wheeling, IL 60090 P: 800-446-3325 www.indeck.com The Indeck Group of Companies is involved in the design and manufacturing of steam and hot water systems. These include water-tube packaged boilers, high temperature hot water generators, rental boilers, heat recovery steam generators and solid fuel boilers, utilizing stoker and bubbling bed technologies. In addition, Indeck also owns the largest inventory of stock boilers available for rent or purchase.
44 ENERGY-TECH.com
Rotork Controls Inc. 675 Mile Crossing Blvd. Rochester, NY 14624 P: 585-247-2304 www.rotork.com Rotork’s electric valve actuator division offers an electrical solution to industrial valve control and actuation applications of virtually any size, description and complexity. Rotork’s unrivalled range of market-leading products offers a robust and economic solution for every valve duty and operating environment.
Structural Integrity Associates Inc. San Jose Corporate HQ 5215 Hellyer Avenue Suite 210 San Jose, CA 95138 P: 877-474-7693 www.strcint.com/energy-tech Structural Integrity is a trusted partner in the energy industry. We do it all: inspection and monitoring, materials evaluations and remaining life assessments, stress and failure analyses, remediation and repair. We manage aging plant assets, oversee fabrication, help with seismic and structural analysis, customize inspection systems, offer ASME Code support, and provide expert opinions.
Unimar 3195 Vickery Rd. N. Syracuse, NY 13212 P: 315-699-4400 www.unimar.com As the leader in smarter obstruction lighting solutions designed specifically to meet your needs, Unimar learns every aspect of your regulatory needs and provides unmatched expertise in designing and building your lighting system. Then we follow up with knowledgeable customer support. The result is greater reliability, economy and performance.
November 2015
MACHINE DOCTOR
Catastrophic centrifugal compressor failure during startup By Patrick J. Smith, Energy-Tech contributor
Preventing machinery failures requires a good machinery condition monitoring program, a good machinery protection system and good maintenance practices. The purpose of the machinery protection system is to ensure that a machine is operated within its normal parameters, provide early detection of a problem and to trip a machine if there is a serious problem. A machinery protection system consists of the instruments that measure the key parameters, and a control system that displays, alarms and/or trips the machine if a parameter exceeds predefined limits. Machinery reliability is the probability that the piece of equipment will perform its intended function without failing for a specified period of time. Machinery protection systems can increase machinery reliability by mitigating damage to the machine when a problem develops. However, the scope and complexity of machinery protection systems, even for similar pieces of equipment, can vary quite a bit. While more sophisticated machinery protection systems can further improve reliability, the additional instruments and controls increase cost, can result in additional operating complexity if there are more constraints to control and can lower machine availability by causing unnecessary trips. As a result standard, less critical compressors in a simple service might have a very simple protection system, while highly engineered, very critical compressors in a complex service might have a more sophisticated protection
system. In either system, some alarm and trip functions might need to be manipulated during transient events, such as start-up, in order to avoid unnecessary trips. However, this also is a time when sudden problems can occur. The purpose of this article is to present a case study where a centrifugal compressor suffered significant damage during a normal start-up.
Figure 1.
Figure 2.
November 2015 ENERGY-TECH.com
45
MACHINE DOCTOR Introduction
Contact Re-Nu® & Lube
m
s
Contact Re-Nu®
m
MS-738
s Vertrel XF Cleaning Agent
MS-730
m
s
Precision Cleaning Solvent
MS-780
m
Plastic, Glass & Metal Cleaner
Acrylic Conformal Coating
m
s MS-580
s
m
s
MS-260
MS-465N
Miller-Stephenson Offers a Wide Range of Chemicals for the Power Industry! Aero-Duster® Contact Cleaners Solvent Cleaners Specialty Cleaners
Krytox™ Lubricants Freeze Spray Conformal Coatings Contact Lubricants
Low Global Warming Formulations Available
m
TM
s Connecticut - Illinois - California - Canada 800 992.2424 203 743.4447 supportET@mschem.com miller-stephenson.com Krytox ™ is a trademark of The Chemours Company FC, LLC
46 ENERGY-TECH.com
This case study pertains to an integrally geared centrifugal compressor driven by a 15.8 MW, 1,500 RPM synchronous motor. The gearbox consists of a bullgear and three rotors. Each rotor consists of a pinion with overhung impellers mounted at each end. The compressor stage 1/2 rotor and stage 3/4 rotor are mounted on the gear case horizontal split line, while the stage 5/6 rotor is installed in a split line in the upper gear case cover. The stage 1 impeller is an open type running against an abradable coated shroud. The stages 2 to 6 impellers are a closed type with labyrinth eye seals. The gas seals at each stage consist of rotating laby teeth running against a carbon bushing. The oil seals at each stage consist of stationary laby teeth running against the shaft. The gearbox configuration for stages 1/2 and 3/4 is shown in Figure 1; the stage 5/6 rotor is omitted for clarity. The gearbox utilizes tilting pad journal bearings for all three pinions with a single non-contacting proximity type shaft vibration probe adjacent to each bearing. The pinions are fitted with thrust collars that transmit pinion axial thrust to the bullgear. The bullgear rotor is fitted with a sleeve type journal bearing on the drive end and a combined sleeve type journal bearing and tapered land type thrust bearings on the non-drive end. There is a single non-contacting type proximity type probe used to measure bullgear axial position. The pinion and bullgear radial and thrust bearings also are all fitted with temperature probes. The compressor protection system includes high pinion vibration alarms, high pinion vibration trips, high pinion and bullgear bearing temperature alarms, a high bullgear axial displacement alarm, and a high bullgear axial displacement position trip.
Failure The compressor is in clean, dry, booster air service and is installed in an unheated enclosure in a northern climate. During commissioning the compressor was started 12 times and had run for a total of approximately 68 hours without any problems. After the commissioning activities were completed, the compressor and all its auxiliary systems were shut down for 3 days waiting for plant production to begin. The weather during this time was fairly cool. As soon as the compressor was started, unusual noises were heard inside the enclosure. The compressor ran for approximately 17 seconds before it tripped. A motor protection relay tripped the motor due to prolonged high current. Analysis of the voltage and current sine waves suggested that the motor reached about 90 percent speed at the point of trip. The damage to the compressor was extensive. The pinion shafts were all snapped off behind the impellers due to hard rubs, with the exception of the stage 2 impeller which had not rubbed. One of the damaged impellers is shown in Figure 2. The stage 1/2 pinion tiling pad pinion bearings are a higher rated design than the other pinion bearings and showed little to no damage. The stage 3/4 and 5/6 pinion bearings were heavily damaged. An example of the damage is shown in Figure 3. November 2015
MACHINE DOCTOR
Figure 3.
It can be seen that the Babbitt was displaced due to very high loads and not wiped due to high temperatures. With the exception of stage 2, the gas seal bushings and corresponding laby teeth were heavily damaged due to hard rubs. The labyrinth oil seals also were badly damaged due to hard rubs. The thrust collars of the pinions showed significant wear, as did the mating thrust faces on the bullgear. There also was significant metallic debris found in the bottom of the gearbox. But, there was no significant damage to motor, coupling, coolers, piping or oil system. The damage was confined to the gearbox.
Investigation Figure 4A shows the vibration trends during the start-up prior to the failure. Figure 4B shows the vibration trends during the start-up when the failure occurred. Comparing the trends, the vibration levels for the start-up when the failure occurred were higher from the moment the compressor was started. About 5 seconds into the start, the vibration levels for stages 1 and 2 increased exponentially to 250 microns p-p, which is the full
range of the transmitters. The vibration levels for stages 3 and 4 also increased exponentially to 250 microns p-p, but lagged behind the stage 1 and 2 vibration increase by approximately 2 seconds. The vibration levels for the stage 5 and 6 showed the same trend, but lagged 2 seconds behind the stage 3 and 4 increase. Note that some of the vibration
REACH YOUR
H2IGHEST
POTEN2TIAL
STREAMLINE OPERATIONS WITH ON-SITE HYDROGEN GENERATION • SAFE • RELIABLE • COMPACT ProtonOnSite.com | 203.678.2000 November 2015 ENERGY-TECH.com 47 • COST-EFFICIENT Info@ProtonOnSite.com ™
MACHINE DOCTOR
Figure 4A.
1511-SCHENCK_1-2i.pdf
1
10/13/15
10:33 AM
Figure 4B.
2VBMJUZ"TTVSBODF
Provided to Our Customers Provided to Our For Over 125Customers Years %DODQFLQJ 0DFKLQHV IRU DOO ,QGXVWULHV For Over 125 Years 0RPHQW :HLJKLQJ 6ROXWLRQV
C
M
Y
CM
MY
CY
CMY
K
Balancing Machines for all Industries 6SLQ 7HVW 6\VWHPV +LJK 6SHHG )DFLOLWLHV Moment Weighing Solutions Vibration Analysis Equipment Spin Test Systems 6FKHQFN $FDGHP\ 6HPLQDUV DQG 7UDLQLQJ High Speed Facilities • It’s a relationship that begins when the negotiations end. Vibration Analysis Equipment • It’s balancing equipment beyond speciďƒž cations and exceedingAcademy expectations. Seminars and Training Schenck
• It’s a higher level of service that is responsive and maximizes performance. • It’s a relationship that begins when the negotiations end. • It’s comprehensive support tobeyond guide you through the and • It’s balancing equipment specifi cations challenges, elevate your capabilities and train your exceeding expectations. experts the future. • It’s a of higher level of service that is responsive and maximizes performance. The Difference is Quality. The Difference is • It’s comprehensive support to guide you through the VT BU elevate your capabilities and train your 7JTJU S (FOchallenges, F of the future. 1PX experts I #PPU HBT /7 F T B - 7
1-800-873-2352
The Difference is Quality. The Difference is www.schenck-usa.com sales@schenck-usa.com
readings drop sharply before the machine trip. This is because these vibration signals went to bad quality. The compressor did not trip because the vibration shutdowns were bypassed for 30 seconds during startup. The compressor typically reaches full speed in about 17-18 seconds on a normal start-up. As shown in figure 4A, on the start-up prior to the failure, the vibration of all the stages spikes just before reaching full speed. It was determined that this was due to excitation from the train torsional natural frequency (TNF). The calculated TNF is 1,250 CPM compared with the operating speed of 1,500 RPM. A field test performed later confirmed this and it was determined that the radial vibration response when the compressor accelerates through the torsional critical speed was normal and not a problem. A review of the process trends during the start-up when the failure occurred did not show anything unusual at first. The machine discharge pressure rose continuously for about 15 seconds, but then suddenly dropped off. The stage inlet temperature trends also appeared consistent with past start-up trends for about 14 seconds, but then the inlet temperatures of stages 3, 4, 5 and 6 rose faster, particularly stage 3. The auxiliary oil pump was started about six minutes prior to starting the compressor. Within this time the minimum oil temperature permissive was satisfied, but the bearing temperatures had not stabilized. The bullgear bearings in particular were still very cold.
Discussion
1-800-873-2352 www.schenck-usa.com sales@schenck-usa.com 48 ENERGY-TECH.com
Many high speed turbomachines operate above their first critical speed and, as a result, pass through one or more resonant frequencies during start-up. This can result November 2015
MACHINE DOCTOR is a problem during start-up. Each case needs to be evaluated in momentary vibration spikes, which is a normal condition. on its own. The magnitude of the vibration spike can depend on a numFor the compressor that is the subject of this article, there ber of factors, such as the amount of rotor unbalance and how were several potential causes for the failure that were reviewed. much damping is present, among others. The vibration level Although there is no direct evidence, it was surmised that the will decay as the rotor speed accelerates past the resonant freshort time that the auxiliary oil pump was run was a major quency. As shown in figure 4A, the vibration levels for the machine that contributing factor to the failure. Compared to the previous start-up, the bearing temperature readings on the start-up when is the subject of this article spike momentarily on some stages the failure occurred had not stabilized, leading to the concluduring the start-up as the particular rotor accelerates through sion that the rotating and static parts had not reached thermal a resonant frequency. And, as noted above, the vibration on all stages spikes when the compressor accelerates through the train torsional natural frequency. The high vibration trip set points are set at values that are lower than some of these vibration spikes. The high vibration set point are based on operation at the normal operating speed. To prevent the machine from tripping during start-up, the Zeeco’s 35-year history of combustion and control system was configured to automatenvironmental successes makes us the ically bypass the high vibration shutdowns breath of fresh air you need to convert for 30 seconds. Although this is a common power plants from coal-fired to natural method to manage vibration spikes during gas, or add low or ultra-low NOx gas-fired start-up, it also eliminates the vibration capability to meet the latest emissions and protection for this period of time. efficiency targets. In a combined cycle facility, To prevent unnecessary high vibration ZEECO® low-NOx duct burners also assist in alarms and trips on start-up and still promeeting clean-air standards. vide high vibration protection, another option is to temporarily elevate the high Zeeco – fresh energy to keep the power and vibration alarm and trip set points. This steam industry generating clean energy. method is recommended by API and is described in API-670, “Machinery Meet the Zeeco Team at Power-Gen Protection Systems.” The elevated vibraInternational Booth #2634 tion alarm and trip set points need to be set higher than the rotors’ characteristic Global experience. response at any resonances during the Local expertise. start-up, but the levels should be set as ZEECO® Low NOx Duct Burner low as possible in order to maximize the machinery protection. In some machines, the alarm and trip points do not need to be elevated at all. In other machines, the alarm and trip set points might need to be elevated by as much as two or even three ® times the normal set points. However, if the set points need to be elevated more than this, there might be a problem that requires further review. There are many different types of control The ZEECO® GB Low NOx power burner fires a variety of gas or Experience the Power of Zeeco. liquid fuels and supports multi-fuel applications without major systems, and in some cases the functionalcombustion control or burner management system modifications. ity of temporarily manipulating alarm and trip set points at start-up might be difficult Zeeco, Inc. to set up. This might result in a higher Boiler Burners • Duct Burners 22151 E 91st St. cost system, more complex controls proBroken Arrow, OK 74014 USA Burner Management • Combustion Control +1 918 258 8551 gramming and a possible increase in the Ignition Systems • Turnkey Solutions sales@zeeco.com potential for an unnecessary trip during start-up. However, having this functionality Explore our global locations at Zeeco.com/global ©Zeeco, Inc. 2015 can lower the damage that is done if there
A Breath of Fresh Air.
November 2015
Energy_Tech_Nov2015.indd 1
10/8/15 49 3:48 PM ENERGY-TECH.com
MACHINE DOCTOR equilibrium. The differential temperatures in the rotors, bearings and casing could have been significant enough to cause distortion and led to hard rubs in the seal areas or impeller running fits, which could have caused the failure.
Conclusions In order to provide additional protection during start-up, the control system for the compressor that is the subject of this article was modified to include elevated high vibration alarm and trip points during start-up. This also is being considered
as a retrofit on other machines. Although the failure described in this article for this type of compressor is uncommon, the consequences can be severe. Whether the additional vibration protection during start-up would have reduced the machine damage will never be known. However, it could lessen the impact if there is another incident and it was not difficult or costly to incorporate this into the compressor control system. As discussed above, the scope and complexity of machinery protection systems should be evaluated on a case by case basis. An additional change was made to the start-up procedures to include a mandatory longer run time for the auxiliary oil pump before starting the compressor. This also is being considered on other machines that operate in colder climates.✸
References 1. API-670, “Machinery Protection Systems”, Fifth Edition, November 2014, API, Washington, DC.” Patrick J. Smith is lead machinery engineer at Air Products & Chemicals in Allentown, Pa., where he provides technical machinery support to the company’s operating air separation, hydrogen processing and cogeneration plants. You may contact him by emailing editorial@ woodwardbizmedia.com.
50 ENERGY-TECH.com
November 2015
November 2015 Advertisers’ Index A-T Controls, Inc.
30, 31
CU Services
6
Cutsforth, Inc.
Back Cover, 43
EagleBurgmann Expansion Joint Solutions
10
ECOM America, Ltd
20
FLEXIM 15 Frederick Cowan & Co,. Inc.
16
Fulmer company
41
Gaumer Process
28
Gradient Lens Corporation
42
Hexeco 12 Hurst Boiler & Welding Company
14
Indeck Power Equipment Co.
32, 33
Miller-Stephenson Chemical Comp. Inc.
18. 46
MTI Instruments
34, 35
Proton Onsite RENTECH Boiler Systems, Inc.
47 Inside Front Cover, 39
Rotork Controls, Inc.
36, 37
Schenck Balancing and Diagnostic Systems
48
Skinner Power Systems
50
SOHRE TURBOMACHINERY INC.
9, 23
Structural Integrity Associates, Inc.
38
Topog-E Gasket Company
19
Unimar -Light & Control Solutions
40
Wabash Power Equipment
29
Zeeco 49
November 2015 ENERGY-TECH.com
51