Quantitative evaluation of leakage flow rate in the sealing part using graphite gland packing to mount a hydrogen separation membrane tube for HI decomposition membrane reaction

杉本 千紘; Myagmarjav, O.; 田中 伸幸; 野口 弘喜; 竹上 弘彰; 久保 真治

International Journal of Hydrogen Energy, 95, p.98 - 107, 2024/12

https://doi.org/10.1016/j.ijhydene.2024.10.334

The thermochemical iodine-sulfur (IS or SI) process can produce hydrogen by decomposing water through chemical reactions and nuclear heat. The hydrogen iodine (HI) decomposition reaction of the IS process thermally decomposes HI at ca. 500C to produce hydrogen. The thermal efficiency of hydrogen production in the thermochemical IS process can be effectively enhanced using a membrane reactor for the HI decomposition reaction; hydrogen separation membrane tubes made of ceramic are attached to a tube plate via sealing parts. The applicability of a sealing method using the expanded graphite grand packing was investigated. During 50 thermal cycles ranging between 25 C-450 C and gas pressure of 0.2-0.8 MPa (gauge), the leakage flow rate was approximately 210 Pa m s. This value is comparable to a detection limit of the standard bubble leak test, indicating that this sealing method works effectively.

Fabrication, permeation, and corrosion stability measurements of silica membranes for HI decomposition in the thermochemical iodine-sulfur process

Myagmarjav, O.; 柴田 愛*; 田中 伸幸; 野口 弘喜; 久保 真治; 野村 幹弘*; 竹上 弘彰

International Journal of Hydrogen Energy, 46(56), p.28435 - 28449, 2021/08

https://doi.org/10.1016/j.ijhydene.2021.06.079

In this study, a corrosion-stable silica ceramic membrane was developed to be used in H purification during the hydrogen iodide decomposition (2HI H + I), which is a new application of the silica membranes. From a practical perspective, the membrane separation length was enlarged up to 400 mm and one end of the membrane tubes was closed to avoid any thermal variation along the membrane length and sealing issues. The silica membranes consisted of a three-layer structure comprising a porous -AlO ceramic support, an intermediate layer, and a top silica layer. The intermediate layer was composed of -AlO or silica, and the top silica layer that is H selective was prepared via counter-diffusion chemical vapor deposition of a hexyltrimethoxysilane. A membrane using a silica intermediate layer exhibited a higher H/SF selectivity but lower H permeance with compared with the membrane using a -AlO intermediate layer. The membrane using the silica intermediate layer was more stable in corrosive HI gas than a membrane with a -AlO intermediate layer after 300 h of stability tests. To the best of our knowledge, this is the first report of 400-mm-long closed-end silica membranes supported on Si-formed -AlO tubes produced via chemical vapor deposition method. In conclusion, the developed silica membranes seem suitable for membrane reactors that produce H on large scale using HI decomposition in the thermochemical iodine-sulfur process.

Development of a membrane reactor with a closed-end silica membrane for nuclear-heated hydrogen production

Myagmarjav, O.; 田中 伸幸; 野村 幹弘*; 野口 弘喜; 今井 良行; 上地 優; 久保 真治; 竹上 弘彰

Progress in Nuclear Energy, 137, p.103772_1 - 103772_7, 2021/07

https://doi.org/10.1016/j.pnucene.2021.103772

Hydrogen production from nuclear energy has attracted considerable interest as a clean energy solution to address the challenges of climate change and environmental sustainability. With respect to the large-scale and economical production of hydrogen using nuclear energy, the thermochemical water-splitting iodine-sulfur (IS) process is a promising method. The IS process uses sulfur and iodine compounds to decompose water into its elemental constituents, hydrogen and oxygen, by using three coupled chemical reactions: the Bunsen reaction; sulfuric acid decomposition; and hydrogen iodide (HI) decomposition. The decomposition of HI is the efficiency-determining step of the process. In this work, a membrane reactor with a silica membrane closed on one end was designed, and its potential for hydrogen production from HI decomposition was explored. In the reactor-module design, only one end of the membrane tube was fixed, while the closed-end of the tube was freely suspended to avoid thermal expansion effects. The closed-end silica membranes were prepared for the first time by a counter-diffusion chemical vapor deposition of hexyltrimethoxysilane. In application, HI conversion of greater than 0.60 was achieved at a decomposition temperature of 400C. Thus, the membrane reactor with closed-end silica membrane was shown to produce a successful equilibrium shift in the production of hydrogen via HI decomposition in the thermochemical IS process.

High temperature gas-cooled reactors

武田 哲明*; 稲垣 嘉之; 相原 純; 青木 健; 藤原 佑輔; 深谷 裕司; 後藤 実; Ho, H. Q.; 飯垣 和彦; 今井 良行; et al.

High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02

https://doi.org/10.1016/C2018-0-05383-9

本書は、原子力機構における今までの高温ガス炉の研究開発の総括として、HTTRの設計、燃料、炉内構造物や中間熱交換器などの要素技術の開発、出力上昇試験、950Cの高温運転、安全性実証試験などの運転経験及び成果についてまとめたものである。また、HTTRでの知見をもとに、商用炉の設計、高性能燃料、ヘリウムガスタービン、ISプロセスによる水素製造などの要素技術開発の現状について記述しており、今後の高温ガス炉の開発に非常に有用である。本書は、日本機械学会の動力エネルギーシステム部門による化石燃料及び原子力によるエネルギーシステムの技術書のシリーズの一冊として刊行されるものである。

Research and development on membrane IS process for hydrogen production using solar heat

Myagmarjav, O.; 岩月 仁; 田中 伸幸; 野口 弘喜; 上地 優; 井岡 郁夫; 久保 真治; 野村 幹弘*; 八巻 徹也*; 澤田 真一*; et al.

International Journal of Hydrogen Energy, 44(35), p.19141 - 19152, 2019/07

https://doi.org/10.1016/j.ijhydene.2018.03.132

Thermochemical hydrogen production has attracted considerable interest as a clean energy solution to address the challenges of climate change and environmental sustainability. The thermochemical water-splitting iodine-sulfur (IS) process uses heat from nuclear or solar power and thus is a promising next-generation thermochemical hydrogen production method that is independent of fossil fuels and can provide energy security. This paper presents the current state of research and development of the IS process based on membrane techniques using solar energy at a medium temperature of 600C. Membrane design strategies have the most potential for making the IS process using solar energy highly efficient and economical and are illustrated here in detail. Three aspects of membrane design proposed herein for the IS process have led to a considerable improvement of the total thermal efficiency of the process: membrane reactors, membranes, and reaction catalysts. Experimental studies in the applications of these membrane design techniques to the Bunsen reaction, sulfuric acid decomposition, and hydrogen iodide decomposition are discussed.

Hydrogen production tests by hydrogen iodide decomposition membrane reactor equipped with silica-based ceramics membrane

Myagmarjav, O.; 田中 伸幸; 野村 幹弘*; 久保 真治

International Journal of Hydrogen Energy, 42(49), p.29091 - 29100, 2017/12

https://doi.org/10.1016/j.ijhydene.2017.10.043

熱化学水素製造法ISプロセスにおいて水素生成する反応であるHI分解反応の分解率を向上させるため、水素分離膜を用いた膜反応器の適用を検討している。本研究では、高性能な水素分離膜を開発するため、HTMOSをシリカ源に用い-アルミナ基材上に対向拡散CVD法を用いて製膜したシリカ膜の性能を調べた。-アルミナに直接製膜した膜よりも-アルミナをコーティングした-アルミナ基材上に製膜した膜の方が、高い水素透過性を示すこと、および、450Cの製膜条件で高い水素選択性ならびに水素透過性が得られることを見い出した。さらに、製膜した膜を適用した膜反応器において、HI分解反応を行い、平衡分解率(20%)を超える0.48の水素転化率を得ることができた。

水素分離膜構造体の中間層の製膜方法及び水素分離膜構造体

野口 弘喜; Myagmarjav, O.

今 肇*

特願 2022-206638  公開特許公報

【課題】水素分離膜構造体の製造において、製膜時の液だれ等によりコーティングのムラ、膜厚の厚い部分の剥離、クラック等の発生を防止する。 【解決手段】水素分離膜構造体の基材である多孔質支持体層を回転させながら、ゾルゲル溶液に多孔質支持体層の表面部分のみを浸漬させ、多孔質支持体層の表面にゾルゲル溶液を塗布する。

Membrane reactor development for efficient thermochemical hydrogen production using high-temperature gas-cooled reactor

Myagmarjav, O.; 田中 伸幸; 竹上 弘彰

no journal, , 

The high-temperature gas-cooled reactor (HTGR) has excellent safety features and can generate heat above 900C, making it possible to effectively use the heat not only for power generation but also for other purposes, such as low-cost, carbon-free hydrogen production. The thermochemical iodine-sulfur process is a promising hydrogen production method suitable for coupling with HTGRs. We, JAEA, have made a significant contribution to the iodine-sulfur process hydrogen production using HTGRs. One of the major challenges in the development of the iodine-sulfur process is the efficient separation of hydrogen during hydrogen iodide (2HI H + I) decomposition. Since the equilibrium conversion of HI decomposition is as low as 20%, it is necessary to introduce membrane reactors with H separation membranes to improve the conversion rate. No membrane exists that can efficiently separate H while handling corrosive gas (HI, I) and high temperature. Therefore, we developed a new silica membrane for H separation with the required properties. Using this membrane, we fabricated a lab-scale membrane reactor and succeeded in increasing the conversion rate of HI decomposition from the current 20% (equilibrium conversion) to the target 70%. This achievement opens up new applications of silica membrane reactor technology for nuclear H production.

Modified dip-coating method for fabrication of pinhole-free supports for hydrogen-separation silica membranes

Myagmarjav, O.; 野口 弘喜; 田中 伸幸; 上地 優; 小野 正人; 竹上 弘彰; 野村 幹弘*; 久保 真治

no journal, , 

Clean and alternative energy are driving global research for sustainability, with a focus on hydrogen production through the innovative thermochemical water-splitting iodine-sulfur (IS) process. This process, powered by solar or nuclear energy, decomposes water into hydrogen, relying on three chemical reactions (Bunsen reaction, sulfuric acid decomposition and hydrogen iodide decomposition. A major challenge is efficiently separating hydrogen from iodine and hydrogen iodide generated during HI decomposition (2HI H + I). Silica membranes offer a promising solution due to their thermal and chemical stability. These membranes are produced as thin silica films carefully coated onto porous supports. However, it is crucial to note that the presence of pinhole defects in these supports can result in an undesirable deterioration, and even the loss of the typical separation capabilities of silica membranes. To address the issue of pinhole defects in the membrane support, a modified dip-coating technique was introduced. This innovative approach utilized rotational dipping, resulting in a new support composed of two distinct layers of -AlO with a gradient structure that demonstrated outstanding pinhole prevention, reproducibility, and a consistently smooth surface. These improvements were achieved through careful consideration of factors such as rotary speed, duration, and coating solution properties.

Development of ceramic membranes for large-scale hydrogen production via thermochemical iodine-sulfur process

Myagmarjav, O.; 田中 伸幸; 野口 弘喜; 久保 真治; 野村 幹弘*; 竹上 弘彰

no journal, , 

Hydrogen is attracting global attention as an energy carrier for future energy delivery systems because of its lack of carbon dioxide emission. To realize a hydrogen energy society, it is necessary to develop effective and safe hydrogen-production methods. The thermochemical iodine-sulfur process is one of the promising methods for massive hydrogen production without carbon dioxide emissions. Separation of hydrogen from gaseous mixture of hydrogen iodide and iodine is one of the technical issues in the development of this process. Silica is the most developed of the porous ceramics and is one of the most promising materials for hydrogen-separation membranes. In the present work, a high performance silica membrane was developed for application in membrane reactors that produce hydrogen by hydrogen iodide decomposition. These silica membranes were prepared with a three-layer structure comprising an porous alumina support layer, an intermediate silica layer fabricated using a sol-gel, and a top silica layer fabricated by counter-diffusion chemical vapor deposition. Scaling up of this type of silica membrane is attempted for the first time in order to produce hydrogen at a large-scale. The resulting membranes exhibit good surface uniformity with length and have no defects, especially existence of pinholes. Thus, these silica membranes appear to be suitable for membrane reactor applications to produce hydrogen in on a large-scale.