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Yoshida, Mitsunori*; Tanaka, Nobuyuki; Okuda, Hiroyuki; Onuki, Kaoru
International Journal of Hydrogen Energy, 33(23), p.6913 - 6920, 2008/12
Times Cited Count:34 Percentile:63.88(Chemistry, Physical)The electro-electrodialysis (EED) for enhancing HI molality in HIx solution (HI-I-HO mixture) of quasi-azeotropic composition was examined at 90 C using Nafion 117 and graphite electrodes. The initial current efficiency of HI molality increase in catholyte varied in the range of 25-80% depending on the operation condition such that the higher iodine molality and the higher weight ratio of anolyte solution to catholyte solution resulted in the higher efficiency. With the progress of EED, the increase rate of the HI molality decreased and, in some cases, concentration limits were observed. Electric conductivity of the HIx solution, overvoltage of the electrode reaction, and voltage drop due to the membrane were measured in the temperature range of 25-120 C, which indicated that the EED cell voltage was governed by the voltage drop due to membrane.
Onuki, Kaoru; Kubo, Shinji; Terada, Atsuhiko; Iwatsuki, Jin; Takegami, Hiroaki; Okuda, Hiroyuki; Kasahara, Seiji; Tanaka, Nobuyuki; Imai, Yoshiyuki
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/10
Japan Atomic Energy Agency has been conducting R&D on thermochemical water-splitting Iodine-Sulfur (IS) process for hydrogen production. Closed-cycle operation of the process was demonstrated for one week with hydrogen production rate of about 30NL/h. Components in HSO section were designed featuring a heat exchanger made of silicon carbide. Flowsheet process analysis is now in progress. For higher thermal efficiency, a Bunsen reactor and an EED cell are investigated. Vapor-liquid equilibrium of HI-HO-I for high pressure is measured.
Hodotsuka, Masatoshi; Yang, X.*; Okuda, Hiroyuki; Onuki, Kaoru
Journal of Chemical and Engineering Data, 53(8), p.1683 - 1687, 2008/07
Times Cited Count:27 Percentile:69.44(Thermodynamics)The isobaric Vapor Liquid Equilibrium(VLE) data in the pressure range of 0.11-0.58MPa where no experimental data had existed was measured for the purpose of increasing VLE data of hydriodic acid which is important physical properties which influence greatly the heat balance and mass balance in the thermochemical IS Cycle. Bubbling point and VLE data of hydriodic acid, which is prepared as adding iodine to almost azeotrope (57%) in the I/HI molar ratio from 0 to 4, were acquired at atmospheric pressure using a glass-made Othemer still. It was confirmed that the ratio of HI/HO of pseudo azeotrope increased as adding iodine. Furthermore, bubbling point and VLE data near the azeotrope in the high pressure range using a tantalum and Hastelloy made Gillespie still. The results quantitatively showed decrese of HI/HO molar ratio of azeotrope as increasing pressure, which used to be estimated by the result of measuring total pressure of hydriodic acid.
Kubo, Shinji; Nakajima, Hayato; Imai, Yoshiyuki; Kasahara, Seiji; Tanaka, Nobuyuki; Okuda, Hiroyuki; Miyashita, Reiko*; Onuki, Kaoru
Proceedings of 17th World Hydrogen Energy Conference (WHEC 2008) (CD-ROM), 4 Pages, 2008/06
A new technique was developed to estimate compositions of Bunsen reaction solution in liquid-liquid phase separation which was targeted on the two solutions in phase equilibrium. In this technique, just two densities measured in the two solution are employed to estimate compositions of two solutions consisting of HI, HSO, I, HO. The fundamental equations underlying this estimation is relations between densities and compositions. To formulate the relations, densities of simulated Bunsen reaction solutions were measured and regression expressions were formulated. Moreover, relational equations for both phases were set up from measured values by the regression procedure. Through estimations of both compositions from both densities, the calculated values are approximately consistent with titrated values. Because of easily and simply execution, this technique is useful for practical use, especially for plant operation and equipment design.
Sakaba, Nariaki; Tachibana, Yukio; Shimakawa, Satoshi; Ohashi, Hirofumi; Sato, Hiroyuki; Yan, X.; Murakami, Tomoyuki; Ohashi, Kazutaka; Nakagawa, Shigeaki; Goto, Minoru; et al.
JAEA-Technology 2008-019, 57 Pages, 2008/03
The small-sized and safe cogeneration High Temperature Gas-cooled Reactor (HTGR) that can be used not only for electric power generation but also for hydrogen production and district heating is considered one of the most promising nuclear reactors for developing countries where sufficient infrastructure such as power grids is not provided. Thus, the small-sized cogeneration HTGR, named High Temperature Reactor 50-Cogeneration (HTR50C), was studied assuming that it should be constructed in developing countries. Specification, equipment configuration, etc. of the HTR50C were determined, and economical evaluation was made. As a result, it was shown that the HTR50C is economically competitive with small-sized light water reactors.
Kubo, Shinji; Imai, Yoshiyuki; Ohashi, Hirofumi; Kasahara, Seiji; Tanaka, Nobuyuki; Okuda, Hiroyuki; Onuki, Kaoru
Proceedings of 2007 AIChE Annual Meeting (CD-ROM), 5 Pages, 2007/11
no abstracts in English
Tanaka, Nobuyuki; Yoshida, Mitsunori; Okuda, Hiroyuki; Sato, Hiroyuki; Kubo, Shinji; Onuki, Kaoru
Proceedings of International Conference on Advanced Nuclear Fuel Cycles and Systems (Global 2007) (CD-ROM), p.833 - 836, 2007/09
Breakdown of the cell voltage in the electro-electrodialysis process for concentrating HIx solution (HI-HO-I mixture) was preliminarily examined in an effort to clarify the optimal operation condition as well as to optimize the cell design for the application to the thermochemical water-splitting IS process for large-scale hydrogen production. Basic data such as electric resistance of HIx solution, overvoltage of the iodine-iodide ion redox reaction at graphite electrode, and the membrane voltage drop, were measured using HIx solution with composition of interest. Also, a methodology for estimating the cell voltage was discussed. The calculated cell voltage agreed well with the experimental one indicating the validity of the procedure adopted.
Terada, Atsuhiko; Iwatsuki, Jin; Ishikura, Shuichi; Noguchi, Hiroki; Kubo, Shinji; Okuda, Hiroyuki; Kasahara, Seiji; Tanaka, Nobuyuki; Ota, Hiroyuki*; Onuki, Kaoru; et al.
Journal of Nuclear Science and Technology, 44(3), p.477 - 482, 2007/03
Times Cited Count:43 Percentile:93.17(Nuclear Science & Technology)Japan Atomic Energy Agency (JAEA) has been conducting study on thermochemical IS process for hydrogen production. A pilot test of IS process is under planning that covers four R&D subjects: (1) construction of a pilot test plant made of industrial materials and completion of hydrogen production test using electrically-heated helium gas as the process heat supplier, (2) development of analytical code system, (3) component tests to assist the hydrogen production test and also to improve the process performance for the commercial plant, (4) design of HTTR-IS system. Development of innovative chemical reactors is in progress, which are equipped with ceramic heat exchanger. In design of the IS plant, it is important to establish the system for "design by analysis". Therefore, we have developed a multi-phase flow analysis code that can analyze systems in which chemical reactions occur
Okuda, Hiroyuki; Yamaki, Tetsuya; Kubo, Shinji
Proceedings of AIChE 2006 Spring National Meeting (CD-ROM), 6 Pages, 2006/00
no abstracts in English
Nomura, Mikihiro*; Okuda, Hiroyuki; Kasahara, Seiji; Nakao, Shinichi*
Chemical Engineering Science, 60(24), p.7160 - 7167, 2005/12
Times Cited Count:28 Percentile:66.11(Engineering, Chemical)The Bunsen reaction (SO+I+2HO=HSO+2HI) in the water-splitting IS process was examined using an electrochemical cell with a cation exchange membrane. The optimal molalities of anolyte and catholyte were evaluated by total thermal efficiency. The I/HI ratio had little effect on the required total voltage; the I/HI ratio can be reduced to 0.5 without decreasing the efficiency. HI and HSO molality greatly affected the efficiency. Membrane resistances are very important parameters affecting the efficiency. The total thermal efficiency increased by 3.0% by increasing the operating temperature from 313K to 363K.
Onuki, Kaoru; Kasahara, Seiji; Tanaka, Nobuyuki; Okuda, Hiroyuki; Yoshida, Mitsunori; Hodotsuka, Masatoshi; Iwatsuki, Jin; Imai, Yoshiyuki; Noguchi, Hiroki; Terada, Atsuhiko; et al.
no journal, ,
Development of efficient HI processing scheme is important for attaining high thermal efficiency of hydrogen production by IS process. We are studying an application of electro-electrodialysis to pre-concentrate the HIx solution before distillation, which is supplied from the Bunsen reaction section. So far, feasibility of the pre-concentration was experimentally verified and also, by flowsheet analysis, the importance was clarified of improving the performance of membrane and electrode catalyst.
Yoshida, Mitsunori; Okuda, Hiroyuki; Hodotsuka, Masatoshi; Kubo, Shinji; Onuki, Kaoru; Hino, Ryutaro
no journal, ,
no abstracts in English
Ijichi, Masanori; Yoshida, Mitsunori; Isaka, Kazuyoshi; Tanaka, Nobuyuki; Kasahara, Seiji; Okuda, Hiroyuki; Hodotsuka, Masatoshi; Kanagawa, Akihiro; Imai, Yoshiyuki; Noguchi, Hiroki; et al.
no journal, ,
no abstracts in English
Hodotsuka, Masatoshi; Okuda, Hiroyuki; Yoshida, Mitsunori; Kubo, Shinji; Onuki, Kaoru; Hino, Ryutaro
no journal, ,
no abstracts in English
Onuki, Kaoru; Kubo, Shinji; Terada, Atsuhiko; Sakaba, Nariaki; Iwatsuki, Jin; Okuda, Hiroyuki; Kasahara, Seiji; Tanaka, Nobuyuki; Imai, Yoshiyuki; Noguchi, Hiroki; et al.
no journal, ,
Japan Atomic Energy Agency has been conducting R&D on thermochemical water-splitting process for hydrogen production. "Closed-cycle" operation features the thermochemical processes, with which all the reactants except water are cyclically used in the component chemical reactions. The closed-cycle operation of pure-thermochemical Iodine-Sulfur process was demonstrated for one week using a glass-made apparatus with hydrogen production rate of about 30NL/h. "Corrosion" is another big technical issue. Based on preliminary corrosion tests in the typical process environments, sulfuric acid decomposer for vaporizing concentrated sulfuric acid at 300-500C and at 2MPa using the sensible heat of high temperature helium gas was designed featuring a heat exchanger made of silicon carbide. Test-fabrication of the ceramic heat exchanger was performed with the capacity equivalent to the hydrogen production rate of 30Nm/h.
Hodotsuka, Masatoshi; Yang, X.*; Okuda, Hiroyuki; Kubo, Shinji; Onuki, Kaoru; Hino, Ryutaro
no journal, ,
no abstracts in English
Yoshida, Mitsunori; Tanaka, Nobuyuki; Okuda, Hiroyuki; Kubo, Shinji; Onuki, Kaoru; Hino, Ryutaro
no journal, ,
no abstracts in English
Hodotsuka, Masatoshi; Yang, X.*; Okuda, Hiroyuki
no journal, ,
The VLE data of Hydriodic acid have been measured.
Okuda, Hiroyuki; Hodotsuka, Masatoshi; Kubo, Shinji; Onuki, Kaoru
no journal, ,
Vapor pressure of hydroiodic acid is necessary for design of distillation column, which is important for improvement of thermal efficiency of IS process. In general, vapor pressure is significant data for getting gas-liquid equilibrium data or azeotropic data, which are necessary for design and operation of distillation separation process. However, the vapor pressure of hydroiodic acid has not almost been known, because it is difficult to design a measurement apparatus to use the corrosive-resistant material for hydroiodic acid such as tantalum, Teflon, and the resisting pressure glass. So, we sellect synthetic method in the measurement method at high pressure such as circulation method, currency method, and static method. Synthetic method has simple structure andsuitable for the measurement of high corrosive material such as supercritical water at high pressure.