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Ohashi, Hirofumi; Sakaba, Nariaki; Imai, Yoshiyuki; Kubo, Shinji; Sato, Hiroyuki; Kato, Ryoma*; Tachibana, Yukio; Kunitomi, Kazuhiko
Nihon Genshiryoku Gakkai Wabun Rombunshi, 8(1), p.68 - 82, 2009/03
A multistage hydrogen iodide (HI) decomposer in a thermochemical water-splitting IS process for hydrogen production using the HTGR is numerically evaluated, especially on the flow rate of undecomposed HI and product iodine at the outlet of the decomposer in order to reduce regenerated heat by recuperates for the recycle of undecomposed HI and eliminate components for the separation. A suitable configuration of the multistage HI decomposer is countercurrent than co-current, and the HIx solution from an electro-electro dialysis at low-temperature is a favorable feed condition for the multistage HI decomposer. An alternative HI processing section using the multistage HI decomposer and eliminating some recuperators and components for the separation is proposed and evaluated. A quantity of regenerated heat by recuperate in the proposed HI processing section can be reduced less than about 1/3 compared with that in the conventional HI processing section.
Sakaba, Nariaki; Ohashi, Hirofumi; Sato, Hiroyuki; Hara, Teruo; Kato, Ryoma; Kunitomi, Kazuhiko
Nihon Genshiryoku Gakkai Wabun Rombunshi, 7(3), p.242 - 256, 2008/09
Nuclear hydrogen production is necessary in an anticipated hydrogen society that demands massive quantity of hydrogen without economic disadvantage. Japan Atomic Energy Agency (JAEA) has launched the conceptual design study of a hydrogen production system with a near-term plan to connect it to Japan's first high-temperature gas-cooled reactor HTTR. The candidate hydrogen production system is based on the thermochemical water-splitting iodine-sulphur (IS) process. The heat of 10 MW that approximately 900
C, which can be provided by the secondary helium from the intermediate heat exchanger of the HTTR, is the energy input to the hydrogen production system. The paper describes the recent progresses made in the conceptual design of advanced process heat exchangers of the HTTR-IS hydrogen production system. A new concept of sulphuric acid decomposer is proposed that integrates three separate functions of sulphuric acid decomposer, sulphur trioxide decomposer and process heat exchanger in the previous design. A new mixer-settler type of Bunsen reactor is also designed that integrates three separate functions of Bunsen reactor, phase separator, and pump in the previous design. The new concepts are expected to result in improved economics through construction and operation cost reductions because the number of process equipment and complicated connections between the equipment has been substantially reduced.
Sakaba, Nariaki; Sato, Hiroyuki; Hara, Teruo; Kato, Ryoma; Ohashi, Kazutaka; Nishihara, Tetsuo; Kunitomi, Kazuhiko
JAEA-Research 2007-058, 31 Pages, 2007/08
JAEA-Research-2007-058.pdf:16.44MB
Since hydrogen produced by nuclear should be competitiveness economically compared by other method in a hydrogen society, it is important to built hydrogen production system to be coupled with the reactor as a conventional chemical plant. Japan Atomic Energy Agency started the safety study to establish a new safety philosophy with safety requirements and with considering non-nuclear grade hydrogen production system for the nuclear coupling system. Also, structural concepts with integrating functions for the Bunsen reactor and sulphuric acid decomposer were proposed to reduce construction cost of the IS process hydrogen production system. In addition, HI decomposer which enabled the process condition to be eased and could adopt conventional materials and technologies was studied. Moreover, basic approval of the HTTR-IS system in which the hydrogen production rate of 1,000 Nm
/h by using the supplied heat of 10 MW from the intermediate heat exchanger of the HTTR was confirmed. This paper describes the conceptual design of the HTTR-IS hydrogen production system.
Kato, Ryoma; Nishihara, Tetsuo; Kunitomi, Kazuhiko
Nihon Genshiryoku Gakkai Wabun Rombunshi, 6(2), p.141 - 148, 2007/06
Japan Atomic Energy Agency (JAEA) has been carrying out design studies of the Gas Turbine High Temperature Reactor 300 for Cogeneration (GTHTR300C). One of the key components in the GTHTR300C is an intermediate heat exchanger (IHX). The IHX for the GTHTR300C is rated 170 MWt and designed on the basis of the shell & tube type IHX adopted by the High Temperature engineering Test Reactor (HTTR). As a conceptual design, we selected the heat exchanger tube size which is based on heat transfer calculation, designed conceptual structure, and evaluated the primary stress in design condition. By the results of this study, the technical feasibility of the large size shell & tube type IHX for the GTHTR300C was verified.
Homma, Hiroyuki; Sato, Hiroyuki; Kasahara, Seiji; Ohashi, Hirofumi; Hara, Teruo; Kato, Ryoma; Sakaba, Nariaki
JAEA-Technology 2007-006, 60 Pages, 2007/02
JAEA-Technology-2007-006.pdf:15.91MB
At the present time, we are alarmed by depletion of fossil energy and adverse effect of rapid increase in fossil fuel burning on environment such as climate changes and acid rain, because our lives depend still heavily upon fossil energy. It is thus widely recognized that hydrogen is one of important future energy carriers in which it is used without emission of carbon dioxide greenhouse gas and atmospheric pollutants and that hydrogen demand will increase greatly as fuel cells are developed and applied widely in the near future. To meet massive demand of hydrogen, hydrogen production from water utilizing nuclear, especially by thermochemical water-splitting Iodine-Sulphur (IS) process utilizing heat from High-Temperature Gas-cooled Reactors (HTGRs), offers one of the most attractive zero-emission energy strategies and the only one practical on a substantial scale. However, to establish a technology based for the HTGR hydrogen production by the IS process, we should close several technology gaps through R&D with the High-Temperature Engineering Test Reactor (HTTR), which is the only Japanese HTGR built and operated at the Oarai Research & Development Centre of Japan Atomic Energy Agency (JAEA). We have launched design studies of the IS process hydrogen production system coupled with the HTTR (HTTR-IS system) to demonstrate HTGR hydrogen production. In designing the HTTR-IS system, it is necessary to consider preventive and breakdown maintenance against accidents occurred in the IS process as a chemical plant. This report describes case study on chemical plant accidents relating to the IS process plant and shows a proposal of accident protection measures based on above case study, which is necessary for flow-sheet design of the HTTR-IS System.
Sakaba, Nariaki; Kato, Ryoma; Hara, Teruo; Sato, Hiroyuki; Nishihara, Tetsuo; Kunitomi, Kazuhiko
no journal, ,
This paper describes the conceptual design of the HTTR-IS hydrogen production system.
Ohashi, Hirofumi; Sakaba, Nariaki; Kubo, Shinji; Imai, Yoshiyuki; Kato, Ryoma*; Kunitomi, Kazuhiko
no journal, ,
JAEA has been developing the hydrogen production system by the thermo-chemical water splitting Iodine-Sulfur (IS) process to produce large amount of hydrogen with the HTGR. In order to increase the HI decomposition rate, alternative multistage HI decomposition process was proposed. It consists of a decomposition section and an iodine removal section, in which iodine is removed from produced gaseous mixture by using HI solution in the process. From the heat and mass balance evaluation, it was confirmed that the decomposition rate increased from 23% of conventional process to 40% by using the multistage decomposition process with 5-stage.
Takahashi, Keita; Kato, Ryoma; Ando, Masanori; Matsuzawa, Hidetsugu*; Nagata, Yuya*; Kaneko, Naoaki*
no journal, ,
no abstracts in English
