Overview of Creep Strength and Oxidation of Heat-Resistant Alloy Sheets and Foils for Compact Heat-Exchangers

Author(s):  
Philip J. Maziasz ◽  
John P. Shingledecker ◽  
Bruce A. Pint ◽  
Neal D. Evans ◽  
Yukinori Yamamoto ◽  
...  

The Oak Ridge National Laboratory (ORNL) has been involved in research and development related to improved performance of recuperators for industrial gas turbines since about 1996, and in improving recuperators for advanced microturbines since 2000. Recuperators are compact, high efficiency heat-exchangers that improve the efficiency of smaller gas turbines and microturbines. Recuperators were traditionally made from 347 stainless steel and operated below or close to 650°C, but today are being designed for reliable operation above 700°C. The Department of Energy (DOE) sponsored programs at ORNL have helped defined the failure mechanisms in stainless steel foils, including creep due to fine grain size, accelerated oxidation due to moisture in the hot exhaust gas, and loss of ductility due to aging. ORNL has also been involved in selecting and characterizing commercial heat-resistant stainless alloys, like HR120 or the new AL20-25+Nb, that should offer dramatically improved recuperator capability and performance at a reasonable cost. This paper summarizes research on sheets and foils of such alloys over the last few years, and suggests the next likely stages for manufacturing recuperators with upgraded performance for the next generation of larger 200–250 kW advanced microturbines.

2005 ◽  
Vol 128 (4) ◽  
pp. 814-819 ◽  
Author(s):  
Philip J. Maziasz ◽  
John P. Shingledecker ◽  
Bruce A. Pint ◽  
Neal D. Evans ◽  
Yukinori Yamamoto ◽  
...  

The Oak Ridge National Laboratory (ORNL) has been involved in research and development related to improved performance of recuperators for industrial gas turbines since about 1996, and in improving recuperators for advanced microturbines since 2000. Recuperators are compact, high efficiency heat-exchangers that improve the efficiency of smaller gas turbines and microturbines. Recuperators were traditionally made from 347 stainless steel and operated below or close to 650°C, but today are being designed for reliable operation above 700°C. The Department of Energy (DOE) sponsored programs at ORNL have helped defined the failure mechanisms in stainless steel foils, including creep due to fine grain size, accelerated oxidation due to moisture in the hot exhaust gas, and loss of ductility due to aging. ORNL has also been involved in selecting and characterizing commercial heat-resistant stainless alloys, like HR120 or the new AL20-25+Nb, that should offer dramatically improved recuperator capability and performance at a reasonable cost. This paper summarizes research on sheets and foils of such alloys over the last few years, and suggests the next likely stages for manufacturing recuperators with upgraded performance for the next generation of larger 200-250kW advanced microturbines.


Author(s):  
Philip J. Maziasz ◽  
Bruce A. Pint ◽  
Robert W. Swindeman ◽  
Karren L. More ◽  
Edgar Lara-Curzio

Compact recuperators/heat-exchangers are essential hardware that increases the efficiency of microturbines and smaller industrial gas turbines. There are several different kinds of recuperator technology (primary surface, plate and fin, spiral, and others), but they all have several common materials needs. Most commercial recuperators today are made from 347 stainless steel sheet or foil. Increased engine size, higher exhaust temperatures and alternate fuels all require greater performance (strength, corrosion resistance) and reliability than 347 steel, especially as temperatures approach or exceed 750°C. To meet these needs, the Department of Energy (DOE) has sponsored programs at the Oak Ridge National Laboratory (ORNL) to measure properties of commercial sheet and foil materials, to analyze recuperator components, and to identify or develop materials with improved performance and reliability, but which also are cost-effective. This paper summarizes high-temperature creep and corrosion testing of commercial 347 used for current recuperators, testing of HR 120 and modified 803 alloys, and development of modified 347 stainless steels.


Author(s):  
Philip J. Maziasz ◽  
Bruce A. Pint

Covers and casings of small to medium size gas turbines, can be made from cast austenitic stainless steels, including grades such as CF8C, CF3M, or CF10M. Oak Ridge National Laboratory (ORNL) and Caterpillar have developed a new cast austenitic stainless steel, CF8C-Plus, that is a fully-austenitic stainless steel, based on additions of Mn and N to the standard Nb-stabilized CF8C steel grade. The Mn addition improves castability, as well as increasing the alloy solubility for N, and both Mn and N act synergistically to boost mechanical properties. CF8C-Plus steel has outstanding creep-resistance at 600°–900°C, which compares well with Ni-based superalloys like alloys X, 625, 617 and 230. CF8C-Plus also has very good fatigue and thermal fatigue resistance. It is used in the as-cast condition, with no additional heat-treatments. While commercial success for CF8C-Plus has been mainly for diesel exhaust components, this steel can also be considered for gas-turbine and microturbine casings. The purpose of this paper is to demonstrate some of the mechanical properties and update the long-term creep-rupture data, and to present new data on the high-temperature oxidation behavior of these materials, particularly in the presence of water vapor.


Author(s):  
Mark van Roode ◽  
Oscar Jimenez ◽  
John McClain ◽  
Jeff Price ◽  
Vijay Parthasarathy ◽  
...  

Impact of foreign or domestic material on components in the hot section of gas turbines with ceramic components is a common cause of catastrophic failure. Several such occurrences were observed during engine testing under the Ceramic Stationary Gas Turbine program sponsored by the U.S. Department of Energy. A limited analysis was carried out at Solar Turbines Incorporated (Solar), which involved modeling of the impact in the hot section. Based on the results of this study an experimental investigation was carried out at the University of Dayton Research Institute Impact Physics Laboratory to establish the conditions leading to significant impact damage in silicon-based ceramics. The experimental set up involved impacting ceramic flexure bars with spherical metal particulates under conditions of elevated temperature and controlled velocity. The results of the study showed a better correlation of impact damage with momentum than with kinetic energy. Increased test specimen mass and fracture toughness were found to improve impact resistance. Continuous fiber-reinforced ceramic composite (CFCC) materials have better impact resistance than monolithics. A threshold velocity was established for impacting particles of a defined mass. Post-impact metallography was carried out at Oak Ridge National Laboratory to further establish the impact mechanism.


Author(s):  
Philip J. Maziasz ◽  
Bruce A. Pint ◽  
John P. Shingledecker ◽  
Karren L. More ◽  
Neal D. Evans ◽  
...  

Compact recuperators/heat-exchangers increase the efficiency of both microturbines and smaller industrial gas turbines. Most recuperators today are made from 347 stainless steel and operate well below 700°C. Larger engine sizes, higher exhaust temperatures and alternate fuels all demand recuperator materials with greater performance (creep strength, corrosion resistance) and reliability than 347 steel, especially for temperatures of 700–750°C. The Department of Energy (DOE) sponsors programs at the Oak Ridge National Laboratory (ORNL) to produce and evaluate cost-effective high-temperature recuperator alloys. This paper summarizes the latest high-temperature creep and corrosion data for a commercial 347 steel with modified processing for better creep resistanc, and for advanced commercial alloys with significantly better creep and corrosion resistance, including alloys NF709, HR120. Similar data are also provided on small lab heats of several new ORNL modified stainless steels.


Author(s):  
Philip J. Maziasz ◽  
Bruce A. Pint

Covers and casings of small to medium size gas turbines can be made from cast austenitic stainless steels, including grades such as CF8C, CF3M, or CF10M. Oak Ridge National Laboratory and Caterpillar have developed a new cast austenitic stainless steel, CF8C-Plus, which is a fully austenitic stainless steel, based on additions of Mn and N to the standard Nb-stabilized CF8C steel grade. The Mn addition improves castability, as well as increases the alloy solubility for N, and both Mn and N synergistically act to boost mechanical properties. CF8C-Plus steel has outstanding creep-resistance at 600–900°C, which compares well with Ni-based superalloys such as alloys X, 625, 617, and 230. CF8C-Plus also has very good fatigue and thermal fatigue resistance. It is used in the as-cast condition, with no additional heat-treatments. While commercial success for CF8C-Plus has been mainly for diesel exhaust components, this steel can also be considered for gas turbine and microturbine casings. The purposes of this paper are to demonstrate some of the mechanical properties, to update the long-term creep-rupture data, and to present new data on the high-temperature oxidation behavior of these materials, particularly in the presence of water vapor.


Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 607
Author(s):  
Tommy R. Powell ◽  
James P. Szybist ◽  
Flavio Dal Forno Chuahy ◽  
Scott J. Curran ◽  
John Mengwasser ◽  
...  

Modern boosted spark-ignition (SI) engines and emerging advanced compression ignition (ACI) engines operate under conditions that deviate substantially from the conditions of conventional autoignition metrics, namely the research and motor octane numbers (RON and MON). The octane index (OI) is an emerging autoignition metric based on RON and MON which was developed to better describe fuel knock resistance over a broader range of engine conditions. Prior research at Oak Ridge National Laboratory (ORNL) identified that OI performs reasonably well under stoichiometric boosted conditions, but inconsistencies exist in the ability of OI to predict autoignition behavior under ACI strategies. Instead, the autoignition behavior under ACI operation was found to correlate more closely to fuel composition, suggesting fuel chemistry differences that are insensitive to the conditions of the RON and MON tests may become the dominant factor under these high efficiency operating conditions. This investigation builds on earlier work to study autoignition behavior over six pressure-temperature (PT) trajectories that correspond to a wide range of operating conditions, including boosted SI operation, partial fuel stratification (PFS), and spark-assisted compression ignition (SACI). A total of 12 different fuels were investigated, including the Co-Optima core fuels and five fuels that represent refinery-relevant blending streams. It was found that, for the ACI operating modes investigated here, the low temperature reactions dominate reactivity, similar to boosted SI operating conditions because their PT trajectories lay close to the RON trajectory. Additionally, the OI metric was found to adequately predict autoignition resistance over the PT domain, for the ACI conditions investigated here, and for fuels from different chemical families. This finding is in contrast with the prior study using a different type of ACI operation with different thermodynamic conditions, specifically a significantly higher temperature at the start of compression, illustrating that fuel response depends highly on the ACI strategy being used.


1988 ◽  
Vol 110 (4) ◽  
pp. 670-676
Author(s):  
R. R. Judkins ◽  
R. A. Bradley

The Advanced Research and Technology Development (AR&TD) Fossil Energy Materials Program is a multifaceted materials research and development program sponsored by the Office of Fossil Energy of the U.S. Department of Energy. The program is administered by the Office of Technical Coordination. In 1979, the Office of Fossil Energy assigned responsibilities for this program to the DOE Oak Ridge Operations Office (ORO) as the lead field office and Oak Ridge National Laboratory (ORNL) as the lead national laboratory. Technical activities on the program are divided into three research thrust areas: structural ceramic composites, alloy development and mechanical properties, and corrosion and erosion of alloys. In addition, assessments and technology transfer are included in a fourth thrust area. This paper provides information on the structure of the program and summarizes some of the major research activities.


Author(s):  
Mark A. Paisley ◽  
Donald Anson

The Biomass Power Program of the US Department of Energy (DOE) has as a major goal the development of cost-competitive technologies for the production of power from renewable biomass crops. The gasification of biomass provides the potential to meet his goal by efficiently and economically producing a renewable source of a clean gaseous fuel suitable for use in high efficiency gas turbines. This paper discusses the development and first commercial demonstration of the Battelle high-throughput gasification process for power generation systems. Projected process economics are presented along with a description of current experimental operations coupling a gas turbine power generation system to the research scale gasifier and the process scaleup activities in Burlington, Vermont.


Author(s):  
Matthew R. Feldman

Based on a recommendation from the Defense Nuclear Facilities Safety Board, the Department of Energy (DOE) Office of Nuclear Safety Policy and Assistance (HS-21) has recently issued DOE Manual 441.1-1 entitled Nuclear Material Packaging Manual. This manual provides guidance regarding the use of non-engineered storage media for all special nuclear material throughout the DOE complex. As part of this development effort, HS-21 has funded the Oak Ridge National Laboratory (ORNL) Transportation Technologies Group (TTG) to develop and demonstrate testing protocols for such onsite containers. ORNL TTG to date has performed preliminary tests of representative onsite containers from Lawrence Livermore National Laboratory and Los Alamos National Laboratory. This paper will describe the testing processes that have been developed.


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