Energy Materials 2017: Materials for Coal-Based Power: Session I
Sponsored by: Chinese Society for Metals
Program Organizers: Jeffrey Hawk, U.S. Department of Energy, National Energy Technology Laboratory; Zhengdong Liu, China Iron & Steel Research Institute Group; Sebastien Dryepondt, Oak Ridge National Laboratory

Tuesday 2:00 PM
February 28, 2017
Room: 12
Location: San Diego Convention Ctr

Session Chair: Jeffrey Hawk, U.S. Department of Energy, National Energy Technology Laboratory

2:00 PM  Keynote
Advances in Materials Technology to Enable Advanced Ultrasupercritical (A-USC) and Supercritical CO2 (sCO2) Power Cycles: John Shingledecker1; 1Electric Power Research Institute
    The U.S. Department of Energy (DOE) and Ohio Coal Development Office (OCDO) sponsored a 14 year effort to develop the materials technology to build and operate an Advanced Ultrasupercritical (A-USC) steam power plant with steam temperatures up to 760°C (1400°F). Based on this highly successful collaborative project, pilot scale test facilities are now in preparation in the U.S. to utilize these materials and processes for both A-USC and supercritical CO2 (sCO2) power cycles. This talk will highlight some of past successes, outline the plans and needs for these pilot scale facilities, and discuss recent ongoing materials research needed to fully apply these technologies. Example of recent research included the application of the developed materials data to valves and other balance of plant (BOP) equipment, materials compatibility with small channel heat exchangers, and continued development of large scale casting and forging through supply chain engagement.

2:40 PM  Invited
Corrosion Issues in Advanced Supercritical and Ultra Supercritical Coal Fired Boilers: Bruce Pint1; 1Oak Ridge National Laboratory
    A multi-year effort has examined high-temperature corrosion issues for current and future coal-fired boilers. On the fireside, there was concern that higher levels of CO2, H2O and SO2 in the recirculated flue gas of oxy-fired systems would accelerate corrosion rates, particularly for Ni-base alloys at 700-800C. Evaluation of commercial and model alloys using synthetic ash and representative gas mixtures indicated little effect of these changes. On the steamside, there is no concern about the steam oxidation resistance of cast or wrought Ni-base alloys up to 800C and no increase in oxide thickness or internal oxidation in steam compared to air. Shot peening of austenitic type 304 stainless steel tubing is highly effective in reducing the oxidation rate in 1 bar steam at 600-650C. However, at 650C, the benefit begins to breakdown after 5,000 h. Research supported by the U.S. Department of Energy, Office of Fossil Energy, Crosscutting Research Program.

3:10 PM  Invited
Materials for Advanced Ultra Supercritical Steam Turbines: Philip Maziasz1; 1Oak Ridge National Laboratory
    The US Program for Advanced Ultra Supercritical (A-USC) steam technology requires materials that can operate long-term at temperatures of up to 760C in order to provide much more efficient and cleaner electric power from coal. Alloy selection for A-USC steam turbines requires rotors, blades and buckets, bolts and cast casings that can operate at these conditions, as well as cast valves and component that connect to the steam supply system. A-USC will need to be made from Ni-based superalloys that have the creep-rupture strength for reliable operation. Currently the US A-USC program has selected Inconel 105 and Haynes 282 alloys for blading and buckets, IN 105 for bolting, and Haynes 282 alloy for the rotor and cast casing applications. This talk will highlight research results on cast scale up and forged rotors and welds of cast Haynes 282 alloy.

3:40 PM Break

4:00 PM  Invited
Heat Resistant Alloy Design: Process Considerations for Microstructural Stability and Long-term Creep Strength in Scaled-Up, Thick Wall Nickel Castings: Paul Jablonski1; Jeffrey Hawk1; 1U.S. Department of Energy, National Energy Technology Laboratory
    High temperature components within conventional coal fired power plants are manufactured from 9% Cr martensitic steels. However, proposed steam temperatures in A-USC power plants are high enough (up to 760C) that 9% Cr martensitic steels will not work due to temperature limitations of the alloy; thus, Ni-based superalloys are considered. Full size castings can be quite substantial: >100 mm thick and weighing at least 5,000 kg or more per piece. Initially, laboratory-scale castings of alloys such as Haynes 282 with comparable thicknesses were manufactured using controlled cooling rate. These were tested satisfactorily with subsequent large scale castings produced commercially. All were subjected to a computationally designed, multi-step homogenization heat treatment specific to the length scale of the microstructures prior to aging. Particular considerations were given to localized chemistries and their impact on phase stability. The mechanical properties of the alloys as well as microstructure are reported here.

4:30 PM  Invited
Ni-Fe Based Alloy GH984G Used for 700℃ Coal-fired Power Plants: Changshuai Wang1; Tingting Wang1; Jianting Guo1; Lanzhang Zhou1; Haiping Zhao2; Songqian Xu2; 1Institute of Metal Research, Chinese Academy of Sciences; 2Research Institute, Baoshan Iron&Steel Co., Ltd.
    To meet the requirements of 700C ultra-supercritical (USC) coal-fired power plants, a new Ni-Fe based alloy (GH984G) has been developed. GH984G has excellent creep strength, thermal stability and resistance to oxidation/corrosion. Harmful phases were not observed even if after thermal exposure at 650-750C for 35,000h. After exposure at 700C for 30,000h, the yield strength has no obvious change. Its 100000h creep strength at 700C is up to 137MPa and comparable to the level of 617B. The oxidation/corrosion evaluate at 700-800C up to 2000h shows that it can meet the requirements of 700C USC coal-fired power plants. Currently, the pipes and tubes with different sizes have been manufactured. Moreover, it is an economic alloy due to the elimination of Co and containing more than 20% Fe. This makes it an interesting alternative for 700C USC coal-fired power plants and is now being evaluated at test platform for key components of China.