Special Issue
Computer Simulation on Energy Development
Review
Computational Simulation Techniques on Solid Catalysts and Their Application to the Mmethane Activation
Hirotaka TSURUYA, Yusuke UEDA, Akira ENDOU, Yasunori OUMI,
Momji KUBO, Kazuo TERAISHI, Salai Cheettu AMMAL and Akira MIYAMOTO
(Department of Materials Chemistry, Graduate School of Engineering, Tohoku University)
Abstract
Recently, computational chemistry has made rapid progress with the development of powerful computer facilities and has been used for the design of novel catalysts. We believe that the combination of the experimental techniques and computational chemistry such as molecular dynamics, quantum chemical calculations and computer graphics would be necessary for the future advancement of the science and technology.
On the other hand, the lack of natural resources in recent days,especially petroleum, is the worldwide crisis, and hence much efforts have been made to utilize the natural gas as alternative energy resources. Therefore the study on the effective usage of methane, which is the main component of natural gas, and its conversion to other fuel or industrial material is an important subject. However methane is very stable thermodynamically and has low reactivity. In order to overcome such problems, heterogeneous catalytic reactions have been expected as one of the effective technology.
Generally, the reactions of methane are categorized into two types; complete oxidation (catalytic combustion) and partial oxidation (synthesis of ethylene, aromatics and methanol, etc.). In both cases, the activation of methane on the solid catalyst is the most important process.
We have applied computational chemistry to investigate the reaction of methane on solid catalysts and to study its adsorption state and activation process. In the present review, we summarized our calculation results of the above processes on supported metal and ion exchanged zeolite catalysts.
Key words : computational simulation, methane activation, solid,catalysts
(Language:Japanese)
Review
Computer Simulation Techniques for Molecular Structure of Coal for Advanced Coal Conversion Technology
Toshimasa TAKANOHASHI (Fundamental Reserch Div., Energy Resources Dept., NIRE)
Kazuo NAKAMURA (Fundamental Reserch Laboratories, Osaka Gas Co., Ltd.)
Masashi IINO (Institute for Chemical Reaction Science, Tohoku University)
Abstract
Coal has a complex chemical structure consisting of various bond types and the details are still not well understood. Recently, in addition to improvements of analytical techniques, molecular modeling and simulation techniques by using powerful computers and software have greatly developed and it has become possible to apply them to complex structure such as coal. Knowledge of coal's molecular structure is important for the understanding of various coal properties and reactivities under several conditions.
In this paper, a new tool, i.e., molecular modeling technique of coal's macromolecular structure and dynamic simulation of coal properties, is introduced and the future applications of this technique will be outlined.
Key words : Computer simulation, Molecular structure of coal, Coal property
(Language:Japanese)
Review
Formation Kinetics of Methane Hydrate: Molecular Simulation Studies
Hiroki NADA (Ocean Mechanics Div., Geotechnology Dept., NIRE)
Abstract
Methane hydrate, which has attracted a great deal of attention as a new energy resource in the 21st century, exists in great volume under the ocean floor around Japan. In order to develop it, the technology to control the formation and dissociation of the hydrate at the molecular level is required. In this review, the formation kinetics of the hydrate is investigated by molecular simulation, such as molecular dynamics and Monte Carlo methods. Besides, subjects to be solved by the simulations in the future are discussed.
Key words : Methane Hydrate, Molecular Dynamics (MD), Monte Carlo (MC), Crystal Growth
(Language:Japanese)
Original Paper
Long-term Simulation by the Integrated Model GRAPE
-A consideration about the land use and the amount of food that can be supplied-
Hiroshi. YAGITA (Rescarch Institute of Innovative Technology for the Earth)
Atsushi. KUROSAWA ( The Institute of Applied Energy)
Weisheng. ZHOU (Rescarch Institute of Innovative Technology for the Earth)
Yukio. YANAGISAWA (Yhe University of Tokyo)
Abstract
The world's food supply and land use were simulated by an integrated model called "GRAPE" about the period of 100 years until the year 2100. The crop land area of the whole world in the year 2100 will is 2.5 times as large as that in the year 2000 to cope with the increases in the demand for food. The developed countries increase production of food (i.e. cereal, chicken and pork) and supply it to developing countries as their increases in the demand for food will exceed what they will be able to produce,
Key words :Land use, Food supply, Integrated model
(Language:Japanese)
Original Paper
A Comparison of Modeled and Observed Sulfur Wet Depositions in China
Takahisaa MAEDA (Inter-Spheric Environment Div., Environmental Assessment Dept., NIRE)
Masayasu HAYASHI (Inter-Spheric Environment Div., Environmental Assessment Dept., NIRE)
Zifa WANG (Institute of Atmospheric Physics, Chinese Academy of Sciences)
Abstract
A modeling of the transport and wet deposition of sulfur oxides in the continental areas of East Asia has been introduced. The calculated wet depositions have been compared with the monthly averaged SO42- concentrations in precipitation observed at 69 locations widely covering China from July through December of 1992. Calculated values including temporal variations was in reasonable agreement with the observations at most locations except in winter, when the wet depositions were overestimated especially in northern areas. A sensitivity study has been introduced to investigate the reason of the overestimation. A total overview of the distribution of the calculated wet deposition was also indicated.
Key words : LRT model, East Asia, Sulfur oxides, Wet deposition
(Language:Japanese)
Original Paper
Model study of the shallow reservoir character at the Hijiori HDR test site
Norio TENMA (Geothermal Energy Technology Dept., New Energy and Industrial Technology Development Orgnization(NEDO))
Isao MATSUNAGA (Director, research planning office, NIRE)
Tsutomu YAMAGUCHI (Geo-Energy Div., Mining and Geotechnology Dept., NIRE)
Michio KURIYAGAWA (Director-General, NIRE)
George ZYVOLOSKI (Los Alamos National Laboratory)
Abstract
A 90-day circulation test (Exp. 9102) was conducted at the Hijioir HDR test site in 1991. During this test, PTS(Pressure - Temperature - Spinner) Logging and six tracer tests were carried out to estimate the characteristics of a shallow reservoir.
To estimate the reservoir characteristics, we calculated the heat extraction area of each outlet points of HDR-3 using the result of PTS logging. Based on the heat extraction area, we attempted to calculate the fracture size of each outlet points of HDR-3 using the result of tracer tests. The simulation code used in this study was FEHM (Finite Element Heat and Mass Transfer) Code, and a 2-well model was used. The results are as follows:
- The main flow-path of the shallow reservoir was fracture between SKG-2 and outlet point 3 of HDR-3.
- Heat extraction areas of each outlet point of HDR-3 were expanding during the 90-day circulation test.
- Especially, heat extraction area of outlet point 3 in the latter period of Exp.9102 was about twice that of outlet point 3 in the early period.
Key words : HDR, PTS Logging, Tracer test, FEHM, Hijiori HDR test site
(Language:Japanese)
Original Paper
Simulation of LPG Energy Storage
Kunihisa KATSUYAMA (Geotechnology Dept., NIRE)
Shinzo KATO (The Institute for Safety of High Pressure Gas Engineering)
Abstract
LPG is used by a large number of households, 23 million in 1990. This number is 55% of households in Japan. LPG consumption per household increased from 108 kg in 1965 to 270kg in1990. The storage rooms of LPG cylinders are usually on the ground surface. In this case, many heavy LPG cylinders are carried and changed manually. In order to save on labor and for storage in the underground to protect from fire, new LPG supply system was proposed and prototype experiments were carried out. Theoretical discussions were also carried out by a 3-dimensional finite difference method in a numerical analysis. The main results obtained are as follows;
- Maximum flame temperature was 780°C when rafters of 2700kg were burned on the ground. Maximum radiant heat was 10100kcal/m2h. A 20 minutes after the ignition, flame temperature and radiant heat became lower.
- The temperature at 0.10 m depth from the ground level was 27.5°C (T=14.5°C) at 1 hour after the ignition, and the temperature at 0.20 m depth did not go higher.
 T=(temperature-original ground temperature=13°C)
- The temperature in the vessel at 1 hour was 14.5°C (T=1.5°C)
- LPG of 6kg or 3kg/h
 8 hours/day5days/week was burned with a burner for a few months. In this case of 6 kg/h, the lowest liquid temperature was -34.4°C, and two days without burning later, the liquid temperature returned to the original temperature.
- The LPG consumption of a typical family was monitored. Theoretical analysis was carried out with the monitored data. The temperature of LPG liquid did not become lower than -4°C (T=-4.5°C) over two weeks from ignition, and the temperature of soil at 0.05 m from the vessel became steady at -2.2°C (T=-2.7°C). The natural vaporization of LPG in the underground vessel was guaranteed.
Key words : LPG, suplly system, simulation, temperature distribution, fire, underground space
(Language:Japanese)
|
