Seiji Kasahara

Development of Hydrogen Production Technology by Thermochemical Water Splitting IS Process Pilot Test Plan

Japan Atomic Energy Agency (JAEA) has been conducting a study on a 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 a hydrogen production test using electrically-heated helium gas as the process heat supplier, (2) development of an analytical code system, (3) component tests to assist the hydrogen production test and also to improve the process performance for the commercial plant, (4) a design study of HTTR-IS system. Development of innovative chemical reactors is in progress, which are equipped with a ceramic heat exchanger. In the design of the IS plant, it is important to establish the system for “design by analysis”. Therefore, we have developed a multiphase flow analysis code that can analyze systems in which chemical reactions occur.

THERMODYNAMIC CONSIDERATIONS ON THE PURIFICATION OF H2SO4 AND HIX PHASES IN THE IODINE-SULFUR HYDROGEN PRODUCTION PROCESS

The reaction equilibrium and phase equilibrium in H2SO4 and HIx phases produced by the Bunsen reaction of the iodine-sulfur thermochemical hydrogen production process were examined using a chemical process simulator, ESP, with a thermodynamic database based on the mixed solvent electrolyte model. At temperatures lower than ca. 110°C, the reaction of HI and H2SO4 produced elemental sulfur in both phases. At higher temperatures, the reverse Bunsen reaction occurred, and SO2 was produced in the H2SO4 phase. In the HIx phase, conversely, SO2 formation predominated in a narrow temperature range and H2S was produced with the increase in temperature. The presence of N2 gas lowered the temperature of the predominant reaction change. A feed of O2 for purification was proposed to suppress the consumption of objective components in the H2SO4 phase purification, and an O2 feed to the HIx phase for the suppression of H2S and S impurities was proposed by the simulation.

Study on Thermochemical Iodine-Sulfur Cycle at JAERI

Japan Atomic Energy Research Institute (JAERI) has been conducting an R&D on thermochemical water-splitting processes of Iodine-Sulfur family, which is a promising candidate of heat-utilization process of High Temperature Gas-cooled Reactors. Present activity at JAERI covers the following three subjects, (a) closed-loop operation technique for stable and continuous hydrogen production by e.g. suppressing possible side reactions, (b) process improvement in terms of thermal efficiency of hydrogen production utilizing membrane technologies, and (c) selection of materials for constructing the large-scale plant mainly focusing on corrosion resistance in the representative process environments. Recent progress on these studies is briefly described.© 2004 ASME

Thermochemical Hydrogen Production IS process

The Japan Atomic Energy Agency (JAEA) is conducting research and development on nuclear hydrogen production using High Temperature Gas-cooled Reactor and thermochemical water-splitting Iodine-Sulfur (IS) process aiming to develop large-scale hydrogen production technology for “hydrogen energy system”. In this paper, the present status of R&D on IS process at JAEA is presented which focuses on examining integrity of such components as chemical reactors, separators, etc. Based on previous screening of materials of construction mainly from the viewpoint of corrosion resistance in the harsh process conditions of IS process, it was planned to fabricate the IS components and examine their integrity in the process environments. At present, among the components of IS process plant consisting of three chemical reaction sections, i.e., the Bunsen reaction section, the sulfuric acid decomposition section and the hydrogen iodide decomposition section, key components in the Bunsen reaction section was fabricated.Copyright

R&D on Thermochemical I-S Process at JAERI

The Japan Atomic Energy Research Institute (JAERI) has conducted a study on the thermochemical water-splitting process of the iodine-sulfur family (IS process). In the IS process, water will react with iodine and sulfur dioxide to produce hydrogen iodide and sulfuric acid, which are then decomposed thermally to produce hydrogen and oxygen. High temperature nuclear heat, mainly supplied by a High Temperature Gas-cooled Reactor (HTGR), is used to drive the endothermic decomposition of sulfuric acid. JAERI has demonstrated the feasibility of the water-splitting hydrogen production process by carrying out laboratory-scale experiments in which combined operation of fundamental reactions and separations using the IS process was performed continuously. At present, the hydrogen production test is continuing, using a scaled-up glass apparatus. Corrosion-resistant materials for constructing a largescale plant and process improvements by introducing advanced separation techniques, such as membrane separation, are under study. Future R&D items are discussed based on the present activities...