Babcock and Wilcox Research Center

Van Buren, OH, United States

Babcock and Wilcox Research Center

Van Buren, OH, United States

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Siefert J.A.,Babcock and Wilcox Research Center | Tanzosh J.M.,Babcock and Wilcox Research Center | Shingledecker J.P.,EPRI
Advances in Materials Technology for Fossil Power Plants - Proceedings from the 6th International Conference | Year: 2011

Dissimilar metal welds (DMW's) between ferritic and austenitic materials at elevated temperatures have concerned boiler manufacturers and operators for decades because of the proven potential for premature failure. With the current trend toward ever higher pressures and temperatures to achieve increased boiler efficiencies, it would be advantageous to have a superior weld metal and joint design that would optimize economy of the newer boilers and help avoid the use of austenitic materials for steam headers and piping. EPRI has developed a new filler metal to improve the performance of DMW's, EPRI P87. Previously, work has been reported on the development of EPRI P87 shielded metal arc welding electrode, gas-tungsten arc welding fine-wire, and the utilization of EPRI P87 in an ultra-supercritical steam boiler built and constructed by B&W. This paper discusses the weldability of EPRI P87 consumables using various test methods such as varestraint testing (trans and spot), long-term creep testing (∼10,000 hour running tests), procedure qualification records of tube to tube weldments between traditional/ advanced austenitics and creep-strength enhanced ferritic steels, and elevated temperature tensile testing. Finally, macros taken from the procedure qualification records were examined using light microscopy to verify the weldability and elimination of cracking between all possible material combinations. All these data show EPRI P87 is a weldable alloy which has a number of advantages for use in DMW applications. The data also show that for specific weld joint configurations, procedure qualifications may require the use of high-temperature tensile data. Copyright © 2011 Electric Power Research Institute Distributed by ASM International®. All rights reserved.


Siefert J.A.,Babcock and Wilcox Research Center | Sanders J.M.,Babcock and Wilcox Research Center | Tanzosh J.M.,Babcock and Wilcox Research Center | Newell Jr. W.F.,EUROWELD LTD. | Shingledecker J.P.,EPRI
Materials at High Temperatures | Year: 2010

Dissimilar metal welds (DMW's) between ferritic and austenitic materials at elevated temperatures have concerned boiler manufacturers and operators for decades because of the proven potential for premature failure. The industry has desired an improved filler metal that would minimize or eliminate DMW failures and, with the current trend toward higher boiler steam pressures and temperatures, have suitable creep strength for joining higher strength materials such as Grade 91 steels After years of research, the Electric Power Research Institute (EPRI) concluded the development and commercialization of a nickel-based filler metal, EPRI P87, for application in shielded metal arc welding (SMAW). This work describes the subsequent development of an EPRI P87 solid wire welding product for application in gas tungsten arc and gas metal arc welding (GTAW and GMAW) processes, and the initial research into the performance of DMWs produced with the new solid wire P87 product. A 135kg heat of solid wire was produced and tested using various welding processes and evaluation methods to ensure that the material would meet required weldability and design specifications. Welding methods included GMAW-P, GTAW and hot-wire GTAW in welds up to 50 mm in thickness. The weld joint tested was a dissimilar metal weld of grade 91 to 347H, which was assessed using microstructure evaluation, creep testing, hot tensile testing, circular patch, and edge build-up investigations to examine hot-cracking susceptibility. This paper summarizes the research completed to date on the EPRI 87 filler wire which supports the acceptability of this material for its intended use in high-temperature power generation applications. © 2010 Science Reviews 2000 Ltd.


Pitz R.W.,Vanderbilt University | Hu S.,Babcock and Wilcox Research Center | Wang P.,Xiamen University
Progress in Energy and Combustion Science | Year: 2014

Tubular flames are ideal for the study of stretch and curvature effects on flame structure, extinction, and instabilities. Tubular flames have uniform stretch and curvature and each parameter can be varied independently. Curvature strengthens or weakens preferential diffusion effects on the tubular flame and the strengthening or weakening is proportional to the ratio of the flame thickness to the flame radius. Premixed flames can be studied in the standard tubular burner where a single premixed gas stream flows radially inward to the cylindrical flame surface and products exit as opposed jets. Premixed, diffusion and partially premixed flames can be studied in the opposed tubular flame where opposed radial flows meet at a cylindrical stagnation surface and products exit as opposed jets. The tubular flame flow configurations can be mathematically reduced to a two-point boundary value solution along the single radial coordinate. Non-intrusive measurements of temperature and major species concentrations have been made with laser-induced Raman scattering in an optically accessible tubular burner for both premixed and diffusion flames. The laser measurements of the flame structure are in good agreement with numerical simulations of the tubular flame. Due to the strong enhancement of preferential diffusion effects in tubular flames, the theory-data comparison can be very sensitive to the molecular transport model and the chemical kinetic mechanism. The strengthening or weakening of the tubular flame with curvature can increase or decrease the extinction strain rate of tubular flames. For lean H 2-air mixtures, the tubular flame can have an extinction strain rate many times higher than the corresponding opposed jet flame. More complex cellular tubular flames with highly curved flame cells surrounded by local extinction can be formed under both premixed and non-premixed conditions. In the hydrogen fueled premixed tubular flames, thermal-diffusive flame instabilities result in the formation of a uniform symmetric petal flames far from extinction. In opposed-flow tubular diffusion flames, thermal-diffusive flame instabilities result in cellular flames very close to extinction. Both of these flames are candidates for further study of flame curvature and extinction. © 2014 Elsevier Ltd. All rights reserved.


Stimpson C.K.,Brigham Young University | Brunner D.R.,Brigham Young University | Reeder T.A.,Brigham Young University | Tree D.R.,Brigham Young University | And 2 more authors.
Western States Section of the Combustion Institute Spring Technical Meeting 2012 | Year: 2012

Deposit samples for eight coals were collected on temperature controlled, stainless steel probes in reducing and oxidizing regions of a 160 kWth , pulverized coal reactor. The samples were analyzed using a scanning electron microscope equipped with energy-dispersive spectroscopy to determine particle sizes and semi-quantitative elemental compositions. An ash analysis was performed on the samples collected from both the top (upstream side) and the bottom (downstream side) of each of the probes. Each particle consisted of a unique composition of elements. The average sulfur concentrations measured in the deposits were not found to correlate with sulfur concentrations of their respective coals, but they were strongly correlated with the calcium and iron contents of their respective coals. The high-calcium, subbituminous and lignite coals produced high sulfur concentrations in the deposits, particularly in the downstream, oxidizing deposits. The high-iron, bituminous coals produced high sulfur concentrations in the deposits; the highest concentrations of sulfur were found in the upstream, reducing deposits. The relatively low-calcium and low-iron bituminous coals produced low sulfur concentrations in the deposits. One coal was an exception to this trend, as the deposits from this coal exhibited low sulfur concentrations despite the high iron concentrations in the coal. The coal highest in pyrite was the only coal that produced discrete deposit particles rich in iron and sulfur but not in calcium. Copyright © (2012) by the Western States Section/Combustion Institute.


Gollihue R.D.,Special Metals Corporation | Baker B.A.,Special Metals Corporation | Dierksheide J.E.,Babcock and Wilcox Research Center | Tanzosh J.M.,Babcock and Wilcox Research Center
Advances in Materials Technology for Fossil Power Plants - Proceedings from the 7th International Conference | Year: 2014

The use of high-nickel superalloys has greatly increased among many industries. This is especially the case for advanced coal-fired boilers, where the latest high temperature designs will require materials capable of withstanding much higher operating temperatures and pressures than current designs. INCONEL® alloy 740H® (UNS N07740) is a new nickel- based alloy that serves as a candidate for steam header pipe and super-heater tubing in coal-fired boilers. Alloy 740H has been shown to be capable of withstanding the extreme operating conditions of an advanced ultra-super-critical (A-USC) boiler, which is the latest boiler design, currently under development. As with all high nickel alloys, welding of alloy 740H can be very challenging, even to an experienced welder. Weldability challenges are compounded when considering that the alloy may be used in steam headers, where critical, thick-section and stub-to-header weld joints are present. This paper is intended to describe the proper procedures developed over years of study that will allow for ASME code quality welds in alloy 740H with matching composition filler metals. Copyright © 2014 Electric Power Research Institute, Inc. Distributed by ASM International®. All rights reserved.


Alexandrov B.T.,Ohio State University | Steiner J.M.,Ohio State University | Strader K.C.,Ohio State University | Feng X.,Ohio State University | And 3 more authors.
Advances in Materials Technology for Fossil Power Plants - Proceedings from the 7th International Conference | Year: 2014

The objective of this study was to determine the typical range of weld metal cooling rates and phase transformations during multipass gas-tungsten arc (GTA) welding of Grade 23 (SA-213 T23) tubing, and to correlate these to the microstructure and hardness in the weld metal and heat affected zone (HAZ). The effect of microstructure and hardness on the potential susceptibility to cracking was evaluated. Multipass GTA girth welds in Grade 23 tubes with outside diameter of 2 in. and wall thicknesses of 0.185 in. and 0.331 in. were produced using Grade 23 filler wire and welding heat input between 18.5 and 38 kJ/in. The weld metal cooling histories were acquired by plunging type C thermocouples in the weld pool. The weld metal phase transformations were determined with the technique for single sensor differential thermal analysis (SS DTA). The microstructure in the aswelded and re-heated weld passes was characterized using light optical microscopy and hardness mapping. Microstructures with hardness between 416 and 350 HV0.1 were found in the thick wall welds, which indicated potential susceptibility to hydrogen induced cracking (HIC) caused by hydrogen absorption during welding and to stress corrosion cracking (SSC) during acid cleaning and service. Copyright © 2014 Electric Power Research Institute, Inc. Distributed by ASM International®. All rights reserved.


Robitz E.S.,Babcock and Wilcox Research Center | Tanzosh J.M.,Babcock
Advances in Materials Technology for Fossil Power Plants - Proceedings from the 6th International Conference | Year: 2011

The U.S. Department of Energy (DOE) and the Ohio Coal Development Office (OCDO) are sponsoring the "Boiler Materials for Ultrasupercritical Coal Power Plants" program to characterize and qualify candidate materials for service in advanced ultrasupercritical (A-USC) boilers. Advanced ferritic materials, austenitic stainless steels and nickel-based alloys are being evaluated. When they are exposed to A-USC boiler conditions, these materials must demonstrate high temperature strength and creep resistance, as well as resistance to both steam-side oxidation and fire side corrosion. As part of the DOE/OCDO program, the fire side corrosion resistance of six monolithic tube materials and twelve weld overlay/tube material combinations were evaluated. The performance of these materials was compared through in situ testing of two superheater test sections within the Unit 1 boiler at Reliant Energy's Niles Plant in Ohio. This boiler burns high sulfur coal and thus provides an aggressive and discriminating test environment. The results of this testing show that, after about 12 months of exposure at temperature, Inconel 740 proved to have the lowest wastage rate among the monolithic tube materials. The results also show that the EN72 weld overlay provided good wastage resistance regardless of the substrate. The relative rankings of all of the candidate materials are provided herein. Copyright © 2011 Electric Power Research Institute Distributed by ASM International®. All rights reserved.


Hu S.,Group W Inc | Hu S.,Babcock and Wilcox Research Center | Zeng D.,Group W Inc | Zeng D.,Babcock and Wilcox Research Center | And 4 more authors.
28th Annual International Pittsburgh Coal Conference 2011, PCC 2011 | Year: 2011

Oxy-coal combustion is a viable technology for curtailing greenhouse gas emissions from coal-fired power plants. It is a process of burning coal with flue gas diluted oxygen. Depending on where the recycled flue gas (RFG) stream is extracted, different combustion characteristics can be expected. "Cold-recycle" and "warm-recycle" modes of oxy-coal combustion are two ways of operating a power plant largely dictated by the fuel sulfur content. Under the warm-recycle condition, the flue gas moisture is not removed from the secondary oxidant stream, and the overall moisture content inside the boiler under steady-state operating condition could reach 35 vol%. The effect of the elevated moisture and CO2 levels on char burnout is the main subject of this study. Previously, char burnout was studied under cold-recycle oxy-coal combustion and air-firing conditions. It was concluded that char-CO2 gasification reactions can play an important role in char burnout. This effect is dependent on both coal rank and combustion condition. Continuing investigation began with the study of the effect of H 2O-rich gas on char burnout under warm-recycle oxy-combustion conditions using a western sub-bituminous coal as compared to the cold-recycle oxy-and air-firing conditions. All three conditions were generated on a flat flame burner (FFB) facility in which gaseous fuel and oxidizer mix and burn rapidly above its surface to produce a high temperature, one-dimensional flame zone. By adjusting the gaseous feed (fuel type, relative flow rate and inert dilution ratio), desired flame environment (temperature, O2/CO 2/H2O levels, etc.) can be generated. The pulverized sub-bituminous coal and its respective char (derived under a hot and inert atmosphere) were fed separately into the flame zone with 4 vol% oxygen that simulated post-flame boiler environment. Char samples at different residence times were collected and their extent of burnout was determined using the ash tracer technique. An optical fiber based two-color pyrometer was used to simultaneously acquire single particle surface temperature and velocity data. Experimental results demonstrated that high CO2 and H2O levels under oxy-firing conditions affect char burnout in two ways. On one hand, the char-CO2 and char-H2O gasification reactions can enhance burnout through direct consumption of char. On the other hand, the endothermic nature of these reactions can lower the particle surface temperature and hence decrease the char oxidation rate, which in turn leads to lower char conversion. The dominance of either effect is dependent on the coal type and the firing conditions (gas temperature, species concentrations, etc.). Char burnout for the sub-bituminous coal in the low-moisture, cold-recycle condition was higher relative to air-firing operation due to the dominance of char gasification by CO2. In contrast, char burnout under warm-recycle oxy-combustion was similar to that of air-firing, indicating that the anticipated char gasification enhancement was equally negated by a cooler particle temperature. The work is accompanied by modeling activities where the char oxidation sub-model in B&W PGG's COMOSM CFD code is evaluated under the test conditions. Both mass release and particle temperature data are predicted using Field's char oxidation sub-model with gasification by both CO2 and H2O considered. New kinetic rate parameters are derived from the experimental results.


Siefert J.A.,Babcock and Wilcox Research Center | Tanzosh J.M.,Babcock and Wilcox Research Center | Ramirez J.E.,Edison Welding Institute
Advances in Materials Technology for Fossil Power Plants - Proceedings from the 6th International Conference | Year: 2011

INCONEL1® alloy 740 is a precipitation-hardenable, nickel-chromium-cobalt alloy with a niobium addition, derived from NIMONIC 1® 263. INCONEL® alloy 740 has been identified as a prime candidate for the severe operating conditions of advanced ultrasupercritical boilers. Compared to other candidate alloys, it exhibits the highest combination of stress rupture strength and corrosion resistance at steam conditions of 760°C (1400°F) and 34.5 MPa (5000 psi). INCONEL® alloy 740 was originally found to be susceptible to liquation cracking in sections greater than 12.7 mm (0.50 in) in thickness. This cracking, through chemical composition modifications of base and weld metal chemistries, has been eliminated. Concern with INCONEL® alloy 740 now lies in the weld strength reduction factor for direct-age weldments. The potential implications of the weld strength reduction factor has enabled further development of welding INCONEL® alloy 740 with Haynes2® 2822®. Haynes® 282® has higher creep strength than INCONEL® alloy 740 and may reduce the weld strength reduction factor. This paper describes successful efforts to eliminate liquation cracking and a comparison of properties between INCONEL® alloy 740 and Haynes® 282® filler materials utilizing the gas tungsten arc welding process. Copyright © 2011 Electric Power Research Institute Distributed by ASM International®. All rights reserved.

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