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decomposition in heat exchanger reactorKubo, Shinji; Tanaka, Nobuyuki; Ohashi, Hirofumi; Kanagawa, Akihiro*; Imai, Yoshiyuki; Kasahara, Seiji; Onuki, Kaoru
Proceedings of 2008 AIChE Annual Meeting (CD-ROM), 8 Pages, 2008/11
SO decomposition is common chemical reaction employed by thermochemical water-splitting cycles for hydrogen. This reaction proceeds endothermically in catalytic bed; in heat utilization system of the VHTR, needed heat is provided from high temperature helium gas by heat exchange. To specify sizes and shape of this reactor, the kinetics of SO decomposition reaction was formulated by a Pt catalyst experiments for primary simple and easy in engineering utilization; besides, the ordinary differential equation for catalytic bed, in which the kinetic and heat exchange were considered, were computed. The characteristics length 
which represented reactor shapes and the required heat transfer area were shown to attain nearly chemical equilibrium.
Kanagawa, Akihiro*; Iwatsuki, Jin; Tanaka, Nobuyuki; Onuki, Kaoru; Fukui, Hiroshi*; Nishibayashi, Toshiki*
JAEA-Technology 2007-061, 32 Pages, 2007/12
JAEA-Technology-2007-061.pdf:21.03MB
Separation of hydrogen iodide from HIx solution (HI-I
-HO mixture) is one of the technical issues in the development of thermochemical IS process. Application of pervaporation (PV) to the concentration of HIx solution in the IS process pilot test plant was discussed from the viewpoints of process heat mass balance, conceptual design of the apparatus, and the corrosion resistance of the membrane module. Compared with the electro-electrodialysis system, the PV system enables the downsizing of apparatus by using hollow fiber membranes, although it does not improve the thermal efficiency of IS process. Immersion tests of commercially available Nafion hollow fiber membrane module in the HIx solution at 100
C indicated the necessity of improving the corrosion resistance of bundle materials.
Kanagawa, Akihiro*; Iwatsuki, Jin; Ishikura, Shuichi; Onuki, Kaoru; Hino, Ryutaro
JAEA-Technology 2007-060, 31 Pages, 2007/11
JAEA-Technology-2007-060.pdf:4.2MB
Thermo-chemical Iodine-Sulfur (IS) process can produce large amount of hydrogen effectively without emission of greenhouse effect gas such as carbon dioxide, where nuclear thermal energy of a high temperature gas-cooled reactor (HTGR) is adopted as a heat source. The IS process uses strong acids such as sulfuric acid and hydriodic acid in high temperature and pressure conditions. Therefore, it is necessary to develop large-size chemical reactors featuring materials that exhibit high temperature and corrosion resistance. A SO decomposer, which is one of key components of the IS process, consists of a pressure vessel for high temperature and high pressure helium gas and an internal structure for SO decomposition by the latent heat of the helium gas. Since joints of the internal structure will be heated up to 700C, we designed a high-temperature joint coupled with coned-disk springs and SiC bolts (coned-disk springs assembly) so as to keep seal performance under high temperature condition. This report presents applicability examination results of designed coned-disk springs assembly as well as seal performance test results of candidate gaskets.
decomposer for thermochemical hydrogen production by IS process; Basic design of SiC plate-type SO decomposer and catalyst test resultsKanagawa, Akihiro; Imai, Yoshiyuki; Terada, Atsuhiko; Onuki, Kaoru; Hino, Ryutaro
JAEA-Technology 2007-043, 54 Pages, 2007/09
JAEA-Technology-2007-043.pdf:27.01MB
Thermo-chemical Iodine-Sulfur (IS) process has a potential to produce large amount of hydrogen without CO emission by using thermal energy of a high temperature gas-cooled reactor (HTGR). In SO decomposer of IS process, SO gas is catalytically decomposed into O and SO under high temperature condition up to 850C using the sensible heat of He gas. The decomposer is exposed to the severe corrosive condition. We proposed a new concept of the decomposer, which featured a plate-type heat exchanger made of SiC ceramics and revealed the results of thermal-hydraulic and mechanical strength analysis. To examine the fabricability of the proposed concept, a mock-up model was test-fabricated and issues on the fabricability of large-sized decomposer were clarified. Also, preliminary catalyst tests were carried out to clarify catalyst bed specification of the SO decomposer.
Iwatsuki, Jin; Terada, Atsuhiko; Noguchi, Hiroki; Imai, Yoshiyuki; Ijichi, Masanori; Kanagawa, Akihiro; Ota, Hiroyuki; Kubo, Shinji; Onuki, Kaoru; Hino, Ryutaro
Proceedings of 14th International Conference on Nuclear Engineering (ICONE-14) (CD-ROM), 8 Pages, 2006/07
JAEA has been conducting the HTTR project from the view to establishing technology base on HTGR and also on the IS process. Based on the test results and know-how obtained through the bench-scale tests, a pilot test plant that can produce hydrogen of about 30 Nm
/hr is being designed. The test plant will be fabricated with industrial materials such as glass coated steel, SiC ceramics etc, and operated under high pressure condition up to 2 MPa. The test plant will consist of a IS process plant and a helium gas (He) circulation facility (He loop). In parallel to the design study, key components of the IS process such as the sulfuric acid (HSO
) and the sulfur trioxide (SO) decomposers working under-high temperature corrosive environments have been designed and test-fabricated to confirm their fabricability. Also, other R&D's are under way such as corrosion, processing of HIx solutions. This paper describes present status of these activities.
Mitsui, J.*; Okada, Y.*; Sakai, F.*; Ide, T.*; Hirata, Kazuhiro*; Yamanishi, Toshihiko; Okuno, Kenji; Naruse, Yuji; Yamamoto, Ichiro*; Kanagawa, Akira*
Fusion Technology, 19(3P2B), p.1646 - 1650, 1991/05
no abstracts in English
Nomura, Yasushi; *; Kanagawa, Akira*
JAERI-M 90-127, 575 Pages, 1990/08
no abstracts in English
decomposer of IS processKanagawa, Akihiro; Imai, Yoshiyuki; 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
decomposition for developing thermochemical IS processKanagawa, Akihiro; Imai, Yoshiyuki; Onuki, Kaoru; Hino, Ryutaro
no journal, ,
no abstracts in English
Iwatsuki, Jin; Terada, Atsuhiko; Noguchi, Hiroki; Kanagawa, Akihiro; Ijichi, Masanori; Kasahara, Seiji; Kubo, Shinji; Sakaba, Nariaki; Onuki, Kaoru; Hino, Ryutaro
no journal, ,
The Japan Atomic Energy Agency (JAEA) has been conducting the HTTR (High-Temperature Engineering Test Reactor) project from the view to establishing technology base on HTGR and also on the IS process. In JAEA, continuous hydrogen production was demonstrated with the hydrogen production rate of about 30 NL/hr for one week using a bench-scale test apparatus made of glass. Based on the test results and know-how obtained through the bench-scale tests, a pilot test plant that can produce hydrogen of about 30 Nm/hr is being designed. The test plant will be fabricated with industrial materials such as glass coated steel, SiC ceramics etc, and operated under high pressure condition up to 2 MPa. In parallel to the design study, key components of the IS process have been designed and test-fabricated to confirm their fabricability. Also, other R&D's are under way such as steady state simulation of pilot system, corrosion resistant seal and piping technology. This paper describes present status of these activities.
Kubo, Shinji; Ohashi, Hirofumi; Kanagawa, Akihiro; Kasahara, Seiji; Imai, Yoshiyuki; Fukui, Hiroshi*; Nishibayashi, Toshiki*; Shimazaki, Masanori*; Miyashita, Reiko*; Tago, Yasuhiro*; et al.
no journal, ,
For a stable hydrogen production, essential problems with the closed-cycle operation are declared, and the cycle can ensure these are retained in a steady state in case the H production rate, O production rate and HO supply rate have equivalent values. Process control methods used to maintain the mass balance of the process were devised, involving the installation of accumulators for the total system, techniques to maintain the Bunsen reaction composition and so on. For the plant operation, both controlled and manipulated variables were determined, while computer simulation and the bench scale H production test were used to confirm control methods. For closed cycle operation for water splitting driven by helium gas heat, the method is discussed to allocate heat for the O and H production sections in strict proportion. Finally, the use of computer simulation for the O production system allowed the key to maintaining heat balance within a cascade heat absorption system to be confirmed.
