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George KOIKE, Kojiro NISHIOKA, Kohei NAGAHARA, Tomoyuki WAKISAKA, Yogo ...
Article type: Article
Pages
295-296
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Recently, polymer electrolyte fuel cells (PEFC) have been developed actively in many laboratories and companies as an environment-friendly power source. One of the important factors determining the performance of a PEFC is a membrane electrode assembly (MEA). The authors have developed a new making method of MEA named "Cast Method". In this study, using a MEA made with this Cast Method, the effect of the MEA structure, especially that of diffusion layers on the performance of a PEFC was investigated.
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Takaaki Mzukami, Hidekazu Fujimura, Shin Takahasi, Kou Takahashi, Hiro ...
Article type: Article
Pages
297-298
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Power generation system using Polymer Electrolyte Fuel Cell (PEFC) is the high efficient of clean electric power. Recently, development of PEFC generation system is accelerated for commercialization. Residence use PEFC cogeneration system has high efficiency, because, it is able to supply electricity and heat together. Residence electricity demands are sharp fluctuations for putting on and off electric household appliances. Residence use PEFC cogeneration system is necessary to follow these demands. Therefore, it is important that PEFC cogeneration system has suitable for rapid response of electricity demands. Response of PEFC cogeneration system is depended on fuel processor. One of our solutions to this object is a use of internal heating fuel processor. Internal heating fuel processor is suitable for rapid start-up and load variation, because reactor catalyst can be heat up directly. This paper presents the result of the characterizations of PEFC cogeneration system.
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Yasuro YAMANAKA, Akira SUZUKI, Minoru MIZUSAWA, Kazunori KOBAYASHI, Hi ...
Article type: Article
Pages
299-300
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The commercialization of PEFC system is expected as minimum scale co-generation system, which will be suitable for small electricity users including restaurants, stores, and gas stations. IHI has developed 5kW PEFC system to utilize various fuels including natural gas an petroleum fuel. This paper describes abstracts of the system.
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Xiaochun Li, Tatsuya Yajima, Takashi Ohsumi, Hitoshi Koide
Article type: Article
Pages
301-302
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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There exist low temperature and high pressure in deep sub-seabed sediments, where many natural gas hydrate fields and free gas reservoirs trapped by them have been discovered. Following these discoveries, CO_2 hydrate sequestration in sub-seabed sediments has been proposed as a novel option for greenhouse gas control, where CO_2 is injected in seated sediments, reacts with pore water and forms hydrates. The hydrate-filled sediments are expected to serve as artificial cap rock, enabling a large volume liquid CO_2 to be stored in the underlying sediments. As a preliminary step toward the development of this technology, attempt is made to show the possible areas for the application of the technology according to the phase behavior, geographic and geologic conditions of the sea areas surrounding Japanese island. The results show that there exist a wide such area in Japan Sea and surrounding Hokkaido.
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Kenji YAMANE, Izuo AYA, Sadahiro NAMIE, Yasuharu NAKAJIMA, Ryuji KOJIM ...
Article type: Article
Pages
303-304
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In 2002,the NMRI started a new international joint research, OACE, Ocean Abyssal Carbon Experiment, with the Monterey Bay Aquarium Research Institute (MBARI, USA) and the University of Bergen (UoB, Norway). The purpose of OACE is to accumulate the basic data on the long-term stability of CO_2 stored on the ocean floor at depths>3500m where liquid CO_2 is gravitationally stable and to evaluate its environmental effects. For this end, several filed experiments at Monterey Bay are planned to get the scientific data concerning the dissolution rate of CO_2,pH distribution around stored CO_2 and the interaction between CO_2 and sediments. The preliminary experiment was conducted in February 2003 at depths 700&800m to provide the know-how and skills for the following experiments at depths>3500m after October, 2003. The experimental procedures and outcome are summarized in this report.
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Takayuki SAITO, Hiroaki KUSANO, Akinori KUMAGAI
Article type: Article
Pages
305-306
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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We have been developing GLAD (Gas Lift Advanced Dissolution) to sequestrate CO_2 at the deep ocean. Local-scale structure of a multiphase flow, such as interfacial motion of individual bubbles, fluid motion in the vicinity of then and their interaction, is strongly required to obtain the best condition for the operation of the system. At the present paper, we will discus surrounding fluid motion of a single bubble zigzag rising in a rest water column on the basis of experiments using LDA and PIV.
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Takeshi Kanai, Katuyoshi Takekuma, Kazunori Sato, Katuroku Takahasi, S ...
Article type: Article
Pages
307-308
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Aiming at reduction of CO_2 contained in the exhaust gas from ships is also considered, for which fuel oil consumption reduction by improvement of ship's propulsive performance and etc. has been earnestly investigated. In this paper dissolution of CO_2 in the exhaust gas bubbles injected into the flow around ship hull is proposed to be one of the powerful candidate for resolution, taking into account the hydrodynamic characteristics of flow around ship hull and chemical property of CO_2 in the large amount of salt water around ships. The system outlined is composed of exhaust gas bubbles injection system, including power needed for injection, hydrodynamics of micro gas bubbles flowing along the ship hull of full scale accompanied with chemical process of CO_2 dissolution, reduction of ship's frictional resistance.
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Yasuharu NAKAJIMA, Hideyuki SHIROTA, Ryuji KOJIMA, Kenji YAMANE, Izuo ...
Article type: Article
Pages
309-310
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Ocean sequestration of carbon dioxide (CO_2) has been expected to be one of technologies for mitigation of the global warming. Injection experiments of liquid CO_2 at 30MPa in a high-pressure tank were carried out to estimate the influence of the ocean sequestration on deep sea environment. The terminal velocity of CO_2 drops sinking in highly pressured water was analyzed by assuming that of rigid spheres with same density to liquid CO_2. The formation rate of CO_2 hydrate film on the surface of CO_2 drops was increased by subcooling. The storage of CO_2 drops on the bottom of the tank for two days provided a pH change of 1.4,and the following stirring of ambient water caused a further pH change of 1.4. These results suggest the dissolution rate of CO_2 into ambient water would be significantly affected by ambient water flow.
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Chisato OYAMA, Takayuki YAMAMOTO, Yutaka ABE, Hideki NARIAI, Kenji YAM ...
Article type: Article
Pages
311-312
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The purpose of the present research is to observe the liquid carbon dioxide (CO_2) injection behavior in high-pressurized water that simulating 500m-depth sea. The experimental conditions are chosen to be under the formation region of CO_2 hydrate, greater pressure than 4.45MPa and lower temperature than 10 degree centigrade. It is expected that the CO_2 hydrate be formed between water phase and liquid CO_2 phase under the conditions. As the result, it is observed that the hydrate membrane formed at the interface of liquid CO_2 jet and water. When the temperature of minus degrees centigrade liquid CO_2 is spouted out into water, a nebula substance is observed to grow from the nozzle. It can be judged that this nebula substance is ice based on the interfacial estimated temperature. This result suggests that the hydrate and ice formation is expected during the low temperature liquid CO_2 injection into the shallow sea.
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Hideo TAJIMA, Ho Teng, Akihiro YAMASAKI, Fumio KIYONO
Article type: Article
Pages
313-314
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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We propose a new injection process of CO_2 using the static mixer for the CO_2 disposal into the intermediate ocean. Liquid CO_2 is released into the ocean after there are agitated with seawater flow in the mixer. Laboratory scale equipment was made to investigate the properties of the static mixer. The drop distribution came to be uniform with the static mixer. The size of drop became small dramatically, and the size was controllable with the water and the CO_2 flow velocity. Under a suitable condition, the formation of CO_2 hydrate was observed without the blockage of the pipe and thus, the CO_2 may be able to release as the hydrate in the ocean by this process. Since the behavior of the CO_2 drops and hydrates released into ocean is determined by its initial size, the injection process using the static mixer is a controllable method of an environmental effect in the ocean.
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Takeshi YOSHIOKA
Article type: Article
Pages
315-316
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The method of sending CO2 to the deep sea, two-phase flow of CO2-gas and sea-water produced by loop type pump is published. Bubble of CO2-gas are able to send to deep-sea more than two-times depth of gas only flow, and disappearing as the increasing as the increasing depth of CO2 bubble and hydraulic pressure due to dissolve and liquefy in the sea-water. After above non-bubble CO2-water are drifted in the sea-water depth 200m to 2000m.
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Shuichiro Hirai, Shoji Tsushima, Hisashi Sanda, Ryoichi Muraoka
Article type: Article
Pages
317-318
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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CO_2 sequestration in ocean, i.e. transportation of liquefied CO_2 removed from flue gas at fossil-fuel-fired power plants through a pipe into the ocean, is considered to be an effective mitigation strategy for global warning due to the increase of CO_2 in the atmosphere. One of the methods considered for implementation is dissolution of CO_2 at intermediate ocean depth using moving ship, where released liquid CO_2 droplets dissolve in the process of rising upward due to buoyancy in the sea water. CO_2 dissolved sea water would be diluted due to the seawater entrainment induced by the turbulent wake of towed pipe for releasing CO_2. Key point of the strategy is how long would it take for CO_2 concentration to be negligibly small. We describe here numerical studies on the evaluation of the dilution of CO_2 at the wake region of moving towed pipe. A numerical simulation employing four equations turbulence model was conducted to elucidate the pH variations in terms of both time and space. CO_2 dilution is fast enough compared to the data of biological impact.
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Toru SATO
Article type: Article
Pages
319-320
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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It is important to predict biological impacts caused by the ocean sequestration of CO_2. For this purpose, a mortality model was developed to predict the acute lethal damage of CO_2 to marine organisms. The model was installed in a LES code with mass transfer, with had been developed in order to reconstruct fluctuating flows in the small-scale ocean based on single-point measurement in the real sea. In the method, small-wavenumber components of fluctuation are forced and large-wavenumber components evolve freely in the computation. Energy spectrum in the wavenumber space is made from the time-sequential data obtained at a single measurement point, assuming the Taylor's hypothesis and spherically even distribution of energy for large eddies. The simulation results suggest that the biological impacts of the CO_2 sequestration can be insignificant in terms of mortality in the cases proposed in this article.
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Kazuyuki HASEGAWA, Akira WADA, Kazuhiro MATUDA
Article type: Article
Pages
321-322
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Global warming caused by the increase of the greenhouse effect gases including carbon dioxide is one of the serious problems for our planet. For preventing further increase in the atmospheric carbon dioxide, a greater attention has been given to the technique to ocean sequestration of carbon dioxide (CO_2), in which CO_2 is directly introduced into the middle or deeper layers of the ocean. Total CO_2 emission in Japan in 1990 was one billion tons. This amount exceeds by about 0.046Gt, the target cut of emission stated in COP3. We examined the behavior of this excess CO_2 that might be continually introduced in the sea off Hawaii of 50 years by 3D-numerical simulation. Injected CO_2 was confined into seawater that was the primary criteria. But biological CO_2 effect of benthos living on the sea bottom was also taken into consideration. It was suggested that CO_2 must be introduced into the layers deeper than 1000m of the Ocean.
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Ryuji KOJIMA, Kenji YAMANE, Izuo AYA
Article type: Article
Pages
323-324
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The CO_2 solubility in hydrate forming conditions shows the dual nature in nature, that is, the solubility with hydrate and without hydrate. These solubilities have the opposite temperature dependence. This dual nature of CO_2 solubility in hydrate-forming conditions exerts a great influence on the evaluation of CO_2 ocean sequestration options proposed so far. Especially in the dissolution type, in which CO_2 is released as droplets in the ocean shallower than 2000 meters, this nature of solubility influences the dissolution rate directly. Therefore, it has to be elucidated what conditions are required for each solubility to prevail and how fast the boundary between two solubility propagates in the real ocean.
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Satoshi SOMEYA, Shigeru BANDO, Masahiro NISHIO, Fumio TAKEMURA, Yongch ...
Article type: Article
Pages
325-326
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Sequestration of liquid CO_2 into intermediate depth ocean or underground has been considered as a means to reduce atmospheric concentration of the greenhouse gas and to mitigate global warming. The solubility of CO_2 into pure water was investigated under high pressure (7-12MPa) condition. Temperature was varied between 3∿20 Celsius degree. CO_2 clathrate hydrate film was formed in lower temperature. Saturated concentrations of CO_2 were determined by expanding dissolved gas. Even with the clathrate sometimes the solubility was quite large as same as without the clathrate, however, it seemed not exactly equilibrium. The solubility decreased with decreasing temperature and with decreasing pressure, though S. Yang, et al. reported it was smaller with higher pressure condition in some lower temperature condition.
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Chisato OYAMA, Yutaka ABE, Hideki NARIAI, Kenji YAMANE, Ryuji KOJIMA, ...
Article type: Article
Pages
327-328
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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It is suggested that the labile cluster structures disassembled from the hydrate membrane in water make the induction time for the hydrate formation shorter than that in the pure water. In the present study, the influence of the liquid CO_2 concentration resolved into water from the hydrate influence on the induction time for the hydrate formation is experimentally investigated. As the result, it is observed that the induction time in the present study is shorter than that of the experimental result for the methane hydrate. There are no remarkable influences of the concentration for hydrate nucleation in the range of 1-1000ppm concentration. The growth rate obtained in this experiment is qualitatively in agreement with the previous researcher's result. The present results indicates that the memory effect of water influence on not the growth rate but on the induction time.
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Yongchen SONG, Masahiro NISHIO, Baixin CHEN, Makoto Akai, Takashi OHSU ...
Article type: Article
Pages
329-330
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Geo-sequestration had been gradually considered to be one of the practical options to mitigate CO_2 concentration from the atmosphere. To estimate and understand the geophysical and geochemical dynamics of injected CO_2 and interactions with reservoir fluids and rocks, the physical properties of CO_2 solution, especially the density, are necessarily the basic data required. With focused on this, an experimental investigation was carried out to directly measure the density and density change of CO_2 saltwater solution. In this paper, the details of the experiments, including the measurement principle and method, and the last measurement results, are reported. It is found, at pressure range from 10.0 to 20.0MPa and temperature from 303.15 to 323.15K, that the density ratio of CO_2 solution to saltwater is increased nonlinearly with the increase of CO_2 mass fraction. The change rate in density due to change in dissolved CO_2 mass fraction appears to be independent on the pressure but sensitive to the temperature. This change rate decreases from 0.26 at temperature of 303.15K to 0.18 at 323.15K while the CO_2 mass fraction is 0.04.
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Shigeru BANDO, Fumio TAKEMURA, Masahiro NISHIO, Eiji HIHARA, Makoto AK ...
Article type: Article
Pages
331-332
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Geological storage of carbon dioxide (CO_2) has been investigated as an option for controlling the emission of carbon dioxide into the atmosphere. When a large amount of CO_2 is sent into an aquifer, there are many non-solved portions about the states and dissolution actions of CO_2,and they need to examine the dynamic action of CO_2 in aquifer enough. Since the elucidation is seldom progressing about the diffusion action of supplied CO_2,it is necessary to accumulate the quantitative data about its dissolution and diffusion action. Then, in this research we will measure the thermophysical properties of CO_2 in aqueous solutions that include an electrolyte such as sodium chloride (following, NaCl), in the pressure and temperature conditions of the underground aquifer. We have measured the solubility of CO_2 in aqueous solutions of NaCl and the viscosity of solutions.
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Amane WASEDA, Takashi UCHIDA
Article type: Article
Pages
333-334
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Natural gas (methane) hydrates were found in the eastern Nankai Trough and the Mackenzie Delta. In both areas, they occur as pore-space fillings in intergranular porosities in coarse-grained (sandy/pebbly) sediments, while fine-grained (muddy) sediments are hydrate-free. Hydrate concentration is high, up to 80%, in pore space in both areas. Based on the carbon and hydrogen isotope compositions, and hydrocarbon compositions, origin of gas in the hydrates in the Nankai Trough are inferred to be microbial reduction of CO_2. The gases in hydrates recovered from other marine sediments around the world are also mainly derived by microbial activities. On the other hand, origin of gas in the Mackenzie Delta is thermogenic decomposition of organic matter. The main origin of gas in hydrates from other permafrost areas is also thermogenic.
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Shinya NISHIO, Eiji OGISAKO, Atsushi DENDA
Article type: Article
Pages
335-336
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Pore scale interactions between methane hydrate and soil grains have a significant effect on the deformation behavior and the strength of methane hydrate bearing sediments. To clarify the nature of those interactions, the triaxial compression tests were performed on sand samples containing ice. The icy samples are relatively easy to prepare and stable at controlled temperature. In addition, the physical properties, i.e. density, Poison's ration and elastic moduli of ice and methane hydrate are similar. Two preparation methods were used, corresponding to different mechanisms of natural methane hydrate accumulation. The test results indicated that the mechanical properties of icy sand samples were affected by both the volume and shape of ice in pore space.
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Masayuki Hyodo, Yukio Nakata, Norimasa Yoshimoto, Tomoka Matsuo, Toshi ...
Article type: Article
Pages
337-338
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Although there has been considerable research on the physical chemical properties of methane hydrate the mechanical properties have yet to be fully investigated. It is important to know these properties in order to allow the extraction of this material under stable conditions. Thus the work described in this paper was aimed at determining the mechanical properties of this material under varying conditions. In order to do this low temperature, high pressure triaxial equipment was developed. Triaxial teste with controlled temperature, confining pressure, strain speed and hydrate content have been carried out on artificial samples of methane hydrate to determine the mechanical properties for the purpose of studying extraction methods and related stability problems. The results confirm that the strength of methane hydrate tends to increase with increasing confining pressure, decreasing temperature, increasing strain speed and increasing hydrate content.
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Takeshi KOMAI, Taro Kawamura, Ji Ho Yoon, Hironori Haneda, Yoshitaka Y ...
Article type: Article
Pages
339-340
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes the extraction system of gas hydrates by replacing CO_2 hydrate and the sequestration of CO_2 under high pressure and low temperature condition. Raman spectroscopy was used to observe directly the behavior on CO_2 hydrate formation under in situ condition. Based on the results, the rate of formation of gas hydrates was quantitatively analyzed using the original conceptual model of formation kinetics.
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Ryoukichi Hamaguchi, Hiroki Yahashi, Yousuke Matsukuma, Masaki Minemot ...
Article type: Article
Pages
341-342
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This study investigates the possibility of the airlift system that is used to recover Methane-Hydrate (MH) from the seabed. As the first step of this study, we calculated unsteady two-phase flow in single-dimension using a numerical procedure based on finite difference method. The optimum depth of gas injection point was found from the relation between the power requirement and superficial velocity of liquid phase. The dynamic and control characteristics of the airlift system for recovering MH were calculated. The decomposition rate of gas hydrate was measured by using R141-b hydrate instead of MH. The effect of methane gas, which is generated by decomposition during passing through the recovery pipe, was investigated. These results show that there is the possibility of establishing the high performance recovery system using the proposed airlift system.
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Toru Iwasaki, Masahiro Takahashi, Yuichi Katou, Katsuhiko Bando, Yoshi ...
Article type: Article
Pages
343-344
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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It is essential for economical transport and storage of natural gas taking advantage of natural gas hydrate pellet to be practiced under as high temperature as possible at the atmospheric pressure. In this study, we produced natural gas hydrate utilizing the mixed gas of mimic natural gas, processed it further into a form of pellet which is superior in the filling efficiency to other forms of natural gas at the time of transport and storage and in fluidity at the time of loading and unloading and examined stability in dissociation under storing temperature. As a result of our assessment thereon under-20 degrees in centigrade, it has been confirmed that a considerably large quantity of gas is contained in hydrate even after two weeks.
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Takahiro KIMURA, Hiromitsu NAGAYASU, Kozo YOSHIKAWA, Katsuhiko BANDO, ...
Article type: Article
Pages
345-346
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes a natural gas transportation system with gas hydrate. This system is called NGH(Natural Gas Hydrate) Chain. It was reported that the capital cost of NGH Chain is 20% lower than LNG Chain^<(1)>. NGH Chain consists of production plant, career and regasification plant. MHI/JNOC have planed 4-step development for NGH production plant : an simulated gas hydrate bench scale test, a methane hydrate bench scale test, a pilot plant test and a commercial plant. This paper reports the simulated gas hydrate bench scale test.
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Yoshihiro Kobayashi
Article type: Article
Pages
347-348
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In order to confirm the hydrate characteristics the methane hydrate was formed under the conditions in sediments of simulated deep sea floor, at the natural interface of methane gas and water and with the forced stirring of gas and water. Formed hydrate was dissociated under conditions of depressurization and heating. The self preservation effects were tested after freezing to a lower temperature and gas stability in the hydrate was confirmed by burning the dissociated methane gas. As the results some features were obtained. To expedite a quick forming of hydrate heat absorption as well as stirring of gas and water are inevitable. Both of heating or depressurization is effective for dissociation but each presents different phenomena. Self preservation effect could be improved by selecting a suitable freezing temperature.
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Hideyuki SHIROTA, Yasuharu NAKAJIMA, Kenjiro HIKIDA, Susumu OTA, Sadah ...
Article type: Article
Pages
349-350
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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For the purpose of sea-borne transport of stranded natural gas in the form of gas hydrate at lower pressure and at higher temperature compared to the conventional liquefied natural gas (LNG) method, the authors are experimentally examining temperature influence upon dissociation behavior of methane hydrate pellets (MHPs) in bulk. The authors designed and made an experimental apparatus that can control the surrounding temperature of dissociating MHPs with high accuracy, and conducted some MHPs dissociation experiments at atmospheric pressure by changing the set-up temperature as a parameter. As a result, it was confirmed that MHPs' dissociation behavior heavily depends upon the temperature.
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Tatsuji KAWASAKI, Ikuo YAMADA, Toshiharu OKUI
Article type: Article
Pages
351-352
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In industrial and commercial facilities, gas composition must be carefully maintained during storage and transportation to guarantee the gas quality. In this study, we investigated composition of gas in hydrate phase formed from city gas and gas phase. As a result, it was found that the thermodynamic stability is greatly influenced by the heavier components, such as ethane, propane and iso-butane that are contained in a natural gas and a city gas. Also it was found that the equilibrium line of hydrates with methane as the main component was shifted to the low-pressure and high temperature side. Especially, in the formation of mixed gas hydrates, it was shown that inclusion rate of methane, the main ingredient, is comparatively low.
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Hiroyuki IDA, Kazuo KOHDA
Article type: Article
Pages
353-354
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A new gas hydrate formation method using micro-bubbles with a tubular reactor was developed and experimental data on hydrate formation and conversion rate for propane are presented. The method achieved higher formation rate over conventional systems and was capable of continuous hydrate formation. Experiments also confirmed an extremely high hydrate conversion rate for gas passing through the system. This excellent performance has the following implications for facilities : 1) Substantially larger formation rate with facilities of the same size, 2) Elimination of cooler-equipped high-pressure vessels required in conventional systems because hydrate formation in the new system takes place inside piping, 3) Simpler and more compact facilities, potentially reducing equipment costs.
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Kazuo KOHDA, Hiroyuki IDA, Katsuhiko BANDO, Yoshifumi SUEHIRO, Toshiha ...
Article type: Article
Pages
355-356
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The bench-scale experimental facility for gas hydrate formation using methane has been designed in order to confirm extremely high formation rate of the newly developed hydrate formation system which uses micro-bubbles with tubular reactor. A static-mixer is used to generate micro-bubbles, and the reactor is 250m long with internal diameter of 16.1mm. The design flow rate of water is 0.014m^3/min and the maximum gas flow rate is 1.12Nm^3/min. Experimental temperature and pressure are 1∿10℃ and 8 MPa at maximum, respectively. A method to analyze hydrate formation in the tubular reactor based on the conservation equations is also presented.
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Sadatoshi MATSUDA, Hidehiko TSUDA, Yasuhiko H. MORI
Article type: Article
Pages
357-358
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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An experimental study has been performed on the water spraying onto a cooled metal-block surface exposed to a hydrate-forming gas as a means of high-rate hydrate formation for the purpose of, for example, natural-gas storage. Special attention has been paid to the effectiveness of conductive cooling of the metal block for removing the heat of hydrate formation directly from the site of the hydrate formation-i.e., the surface of the metal block. HFC-32 that forms a hydrate of structure I at moderate pressures was used as a model gas to enable visual observations of hydrate formation inside a large-windowed spray chamber. The operational parameters that we varied in the present experiments were the pressure inside the chamber, the temperature of water just before spraying, and the surface temperature of the metal block. Throughout each experimental run, we continuously measured the rate of HFC-32 supply to the chamber to maintain the pressure at a prescribed level and also the heat-flow rate through the metal block to the outside of the chamber.
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Ryo OHMURA, Tsutomu UCHIDA, Satoshi TAKEYA, Ikuko Y. IKEDA, Jiro NAGAO ...
Article type: Article
Pages
359-360
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Clathrate hydrate formation in methane/isoamylalcohol (3-methyl-1-butanol)/water system has been demonstrated. The first data of quadruple methane/3-methyl-1-butanol/hydrate/water equilibria have been determined over the temperature range of 274-281 K. The equilibrium pressures at the temperatures below 279 K are lower than those of structure-I hydrate formed in methane/water system without 3-methyl-1-butanol. At the temperatures higher than 279 K, the equilibrium pressures are higher than those of the structure-I methane hydrate. Hydrate crystal samples are prepared under two conditions : at 274 K under 2.55 MPa and at 280.0 K under 6.30 MPa. The crystal samples are then subjected to the Raman-spectroscopy and X-ray-diffraction measurements for the determination of the crystallographic structures of the hydrate crystals. The measurements showed a hydrate phase transition depending on the temperature.
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Hajime Endou, Schuichirou, Akiko Hirano, Kazuhiko Murakami, Daisuke H ...
Article type: Article
Pages
361-362
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The new concept of CO2 separation of prior to combustion was proposed, that CO2 is separated from the H2-CO2 mixed gas produced by steam-reforming of hydrocarbon fuel by means of Gas Hydrate Separation (GHS) system. In order to demonstrate the reality of the GHS system, we conducted experiments of CO2 and CO2-He mixed gas hydrate formation. GH reaction is confirmed but not succeeded in continuous operation of gas formation system, so far.
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Hiroyuki NISHIMOTO, Masahiro OTA, Hajime ENDOU
Article type: Article
Pages
363-364
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In this study, a CO_2-hydrate is produced from the mixed gases of CO_2 and Helium. The hydrate is formed from CO_2. On the other hand, the hydrate isn't formed from Helium. The purpose of this study is to reveal the characteristics of gas separation using hydrate production technology. The molecule of CO_2 enter the crystal of the molecule of water, then a CO_2-hydrate is formed. A CO_2-hydrae is the crystal of a solid like ice and stables at low temperature and high pressure. In normal temperature and normal pressure, a CO_2-hydrate decompose and become gas and water.
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Takeshi SUGAHARA, Toshiyuki NAKAMURA, Noriyuki SHIMADA, Keisuke SUGAHA ...
Article type: Article
Pages
365-366
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Thermodynamic stability boundaries for structure-H hydrates of heavy hydrocarbon species in the presence of methane were investigated in the temperature range of 273 - 290 K and pressure range up to 10 MPa. The hydrate formation reveals that the cage-occupancy limit of the largest cage locates between the dimethylcyclohexane stereo isomers. Only 1,1-, cis-1,2- and cis-1,4-dimethylcyclohexanes can generate structure-H hydrate in seven types of dimethylcyclohexane stereo isomers.
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Takayuki YAMAMOTO, Yutaka ABE, Hideki NARIAI, Kenji YAMANE, Ryuji KOJI ...
Article type: Article
Pages
367-368
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The strength of CO_2 hydrate membrane which forms at the interface between liquid CO_2 and CO_2 rich water at about 45MPa was measured by Du-Nouy type surface tension meter. As the result, the strength at the saturated condition shows about 10 times stronger than the case of fresh water. In addition, the membrane shows abnormal strength and stiffness compared with the un-saturated condition. The abnormality just below the dissociation temperatures, which had been found in fresh water, also appeared in this experiment. However, its peak decreases with CO_2 concentration rise. In this paper, the abnormality just below the dissociation temperatures was quantitatively estimated with the idea that the diffusion of H_2O molecules is derived by analogy with Gibbs-Free-Energy. In addition, the stiffness was qualitatively explained by taking into consideration the diffusion and the arrangement of CO_2 molecules in the membrane.
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Izuo AYA, Hideyuki SHIROTA, Yasuharu NAKAJIMA, Sadahiro NAMIE, [in Jap ...
Article type: Article
Pages
369-370
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Recently-discovered self-preservation phenomenon of gas hydrate, slow dissociation rate at out of hydrate forming condition, has attracted much attention to utilize for the shipping of natural gas as hydrate from. It was reported that this phenomenon appears strongly in very limited temperature ranges at several Celsius below zero. The experiment conducted at the National Maritime Research Institute, however, did not show such conspicuous self-preservation in the same temperature ranges. Then the authors propose a new model of self preservation basing on the assumption that the dissociation probability of hydrogen bond near the freezing point of water has a meaningful value compared with the association probability and makes the ice strong by restoring the cracks in the ice layer surrounding hydrate mass. This model can well explain the self preservation phenomenon and its strong temperature dependence. The different experimental results were also explained by combining the above model and the size dependent nature of plastic deformation of ice.
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Tomoya TSUJI, Toshihiko HIAKI, Katsuto OTAKE, Takaji AKIYA
Article type: Article
Pages
371-372
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Solid-liquid equilibrium (SLE), containing clathrate hydrate formation, was measured for tertahydrofurane (THF) + water (H_2O) system by use of a static type apparatus at 272.07-277.64 K. The experimental data were correlated with Schroder-van Laar equation assuming ideal solution and group contribution model of heat of fusion for THF・17H_2O hydrate. The density of THF hydrate was also measured by use of a flow type apparatus at 276.37 K. An oscillation U-tube densimeter was equipped with the apparatus, and the apparent density was measured for the mixture of liquid and THF・17H_2O hydrate. Using the calculated SLE, and mass and volume balances in the oscillation U-tube, the density of THF・17H_2O hydrate was estimated to be 999.04kg/m^3. The value was close to the theoretical one, 999.14kg/m^3.
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Tetsu ITOTAGAWA, Sho WATANABE, Hiroshi SUZUKI, Hiromoto USUI
Article type: Article
Pages
373-374
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In order to investigate the drag reduction methodology for clathrate hydrate slurries that can transport high-density heat, the pressure drop measurements of the slurries treated with surfactant additives have been performed. A cationic surfactant of bishydroxyethylmethylanmonium chloride was applied at the concentration of 2,000 ppm as a drag reducer for trimethylolethane (TME) clathrate hydrate slurry, From the results, the surfactant drag reduction is found effectively to reduce the friction drag of clathrate hydrate slurries up to the hydrate particle fraction of 11%. A feasibility study for air-conditioning system of a certain building reveals the hydrate slurries treated with surfactants drastically reduce the pumping power.
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Article type: Appendix
Pages
App2-
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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