Through Wall Cracking in High Temperature Rotary Cooler

2009 ◽  
Author(s):  
James Frith ◽  
Robert Frith
Keyword(s):  
High Temperature ◽  
Corrosion Fatigue ◽  
Design Principle ◽  
Extreme Temperature ◽  
Fatigue Cracking ◽  
Water Dissociation ◽  
Thermally Induced ◽  
Corrosion Fatigue Crack ◽  
Root Cause ◽  
High Temperature Operation

After operating for a number of years, a high temperature rotary ore cooler suffered cracking. The cracks grew through the shell wall resulting in leakage of water from the water bath into the ore. Under the extreme temperature, the risk of water dissociation into hydrogen and subsequent explosion was of substantial concern and instigated the investigation in to the root cause of the cracking which was deduced to be driven by high thermally induced stresses. The root cause for the thermally induced stressing was found to be related to a design flaw that was not immediately obvious. The investigation outcome was a recommendation to change the design to eliminate the high localized stresses which were believed to be the driving force behind the corrosion fatigue crack propagation. This paper presents the investigation approach which included advanced thermal and stress analysis and reports on the general design principle that should be adopted to avoid thermal stress induced corrosion fatigue cracking under high temperature operation.

A Dynamic Modeling Methodology to Estimate the Magnitude of Unwanted Liquid Flows in High Temperature Boiler Components

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Gary de Klerk ◽  
Pieter Rousseau ◽  
Louis Jestin
Keyword(s):  
High Temperature ◽  
Power Plants ◽  
Fatigue Cracking ◽  
Momentum Equation ◽  
Temperature Gradients ◽  
Root Cause ◽  
Modeling Methodology ◽  
Tracking Model ◽  
Liquid Flows ◽  
Control Volumes

Abstract Due to the penetration of variable renewable energy (VRE) sources into electricity supply grids, conventional coal fired power plants need to operate with greater flexibility while remaining reliable and conserving the lifetime of components. Thick-sectioned components are prone to thermal fatigue cracking as a result of through-wall temperature gradients. These temperature gradients can be significantly amplified during quenching when components at high temperature are unintentionally exposed to colder liquid or steam. Such quench events are known to occur during two-shift operation of a large once-through coal fired tower type boiler. The purpose of this study is to develop and demonstrate a model that can be used to determine the root cause and magnitude of quenching. The model is developed using the least level of detail to make it readily usable by power plant engineers. Two different approaches are used. A liquid tracking model (LTM) was developed from first principles that approximates the liquid level in the superheater as a function of time. The model is presented and verified by comparison with real-plant data. The second approach was to configure a model in flownex, which is a commercially available software package. The LTM model with eight control volumes provided better steam temperature results and was able to simulate the correct superheater pressure behavior without solving the momentum equation. The models proved that a separator overflow was the cause of quenching for this particular case study.

High Temperature Operation Limit Assessment for 4H-SiC Schottky Diode-Based Extreme Temperature Sensors

2019 ◽  
Vol 19 (5) ◽  
pp. 1640-1644 ◽  
Author(s):  
Vasily A. Krasnov ◽  
Stanislav V. Shutov ◽  
Sergey Yu Yerochin ◽  
Oleksii M. Demenskyi
Keyword(s):  
High Temperature ◽  
Schottky Diode ◽  
Extreme Temperature ◽  
Temperature Sensors ◽  
High Temperature Operation

High-Temperature Operation of Photonic-Crystal Lasers for On-Chip Optical Interconnection

2012 ◽  
Vol E95.C (7) ◽  
pp. 1244-1251 ◽  
Author(s):  
Koji TAKEDA ◽  
Tomonari SATO ◽  
Takaaki KAKITSUKA ◽  
Akihiko SHINYA ◽  
Kengo NOZAKI ◽  
...  
Keyword(s):  
High Temperature ◽  
Photonic Crystal ◽  
Optical Interconnection ◽  
On Chip ◽  
High Temperature Operation

KUBOTA UCX

Alloy Digest ◽  
2008 ◽  
Vol 57 (6) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Temperature Performance ◽  
High Temperature Operation ◽  
Oxidation And Corrosion ◽  
Very High

Abstract Kubota UCX was developed for very high temperature operation for ethylene pyrolysis service. The alloy also has excellent oxidation and corrosion resistance. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as casting and joining. Filing Code: Ni-663. Producer or source: Kubota Metal Corporation, Fahramet Division.

Impact of Metal Pad Etch-Induced Plasma Damage on Dynamic Retention Time Degradation during High Temperature Stress in High Density DRAM Technology

2005 ◽  
Author(s):  
D-J Kim ◽  
I-G Kim ◽  
J-Y Noh ◽  
H-J Lee ◽  
S-H Park ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Stress ◽  
Retention Time ◽  
High Temperature Stress ◽  
High Density ◽  
Cell Junction ◽  
Antenna Effect ◽  
Plasma Damage ◽  
Root Cause ◽  
Wafer Processing

Abstract As DRAM technology extends into 12-inch diameter wafer processing, plasma-induced wafer charging is a serious problem in DRAM volume manufacture. There are currently no comprehensive reports on the potential impact of plasma damage on high density DRAM reliability. In this paper, the possible effects of floating potential at the source/drain junction of cell transistor during high-field charge injection are reported, and regarded as high-priority issues to further understand charging damage during the metal pad etching. The degradation of block edge dynamic retention time during high temperature stress, not consistent with typical reliability degradation model, is analyzed. Additionally, in order to meet the satisfactory reliability level in volume manufacture of high density DRAM technology, the paper provides the guidelines with respect to plasma damage. Unlike conventional model as gate antenna effect, the cell junction damage by the exposure of dummy BL pad to plasma, was revealed as root cause.

scholarly journals Identification of Existing Challenges and Future Trends for the Utilization of Ammonia-Water Absorption–Compression Heat Pumps at High Temperature Operation

2021 ◽  
Vol 11 (10) ◽  
pp. 4635
Author(s):  
Marcel Ulrich Ahrens ◽  
Maximilian Loth ◽  
Ignat Tolstorebrov ◽  
Armin Hafner ◽  
Stephan Kabelac ◽  
...  
Keyword(s):  
High Temperature ◽  
Water Absorption ◽  
Industrial Sector ◽  
Heat Pumps ◽  
Working Fluid ◽  
Large Temperature ◽  
Future Trends ◽  
Ammonia Water ◽  
Starting Point ◽  
High Temperature Operation

Decarbonization of the industrial sector is one of the most important keys to reducing global warming. Energy demands and associated emissions in the industrial sector are continuously increasing. The utilization of high temperature heat pumps (HTHPs) operating with natural fluids presents an environmentally friendly solution with great potential to increase energy efficiency and reduce emissions in industrial processes. Ammonia-water absorption–compression heat pumps (ACHPs) combine the technologies of an absorption and vapor compression heat pump using a zeotropic mixture of ammonia and water as working fluid. The given characteristics, such as the ability to achieve high sink temperatures with comparably large temperature lifts and high coefficient of performance (COP) make the ACHP interesting for utilization in various industrial high temperature applications. This work reviews the state of technology and identifies existing challenges based on conducted experimental investigations. In this context, 23 references with capacities ranging from 1.4 kW to 4500 kW are evaluated, achieving sink outlet temperatures from 45 °C to 115 °C and COPs from 1.4 to 11.3. Existing challenges are identified for the compressor concerning discharge temperature and lubrication, for the absorber and desorber design for operation and liquid–vapor mixing and distribution and the choice of solution pump. Recent developments and promising solutions are then highlighted and presented in a comprehensive overview. Finally, future trends for further studies are discussed. The purpose of this study is to serve as a starting point for further research by connecting theoretical approaches, possible solutions and experimental results as a resource for further developments of ammonia-water ACHP systems at high temperature operation.

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