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• 氷点下温度域におけるクラスレートハイドレートの相平衡条件と結晶構造

  2015年03月 

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• Phase equilibrium conditions in carbon dioxide + cyclopentane double clathrate hydrate forming system coexisting with sodium chloride aqueous solution

  Kouki Mekaru, Takuto Miyagi, Ayaka Mishima, Isami Uehara, Ryo Ohmura, Keita Yasuda

  The Journal of Chemical Thermodynamics ( Elservier )  189   107185   2024年02月 [ 査読有り ]

  掲載種別: 研究論文（学術雑誌）

  • この論文にアクセスする
    DOI

• Renewed Measurements of Carbon Dioxide Hydrate Phase Equilibrium

  Haruki Ito, Akari Gibo, Sayaka Shiraishi, Keita Yasuda, Ryo Ohmura

  International Journal of Thermophysics ( Springer )  44   128   2023年08月 [ 査読有り ]

  掲載種別: 研究論文（学術雑誌）

  　概要を見る

  This paper investigates the phase equilibrium conditions in the carbon dioxide hydrate forming system. Carbon dioxide hydrate can be utilized for carbon capture, salt manufacture, carbonated solid foods and tritium water concentration, so the phase equilibrium conditions have been substantially reported so far. However, the data from previous studies were inconsistent with each other, such as there is a difference of 1.0 K in the phase equilibrium temperature at 2 MPa. In this study, the newly three-phase (water rich liquid + hydrate + guest rich vapor) equilibrium conditions in the carbon dioxide hydrate forming system were measured at twenty different temperature conditions within the range of (271.9-282.7) K in the two different laboratories. The six pairs of the three-phase equilibrium condition data measured under equivalent pressure conditions were consistent within mutual uncertainties. The internal consistency of the data measured in this study was evaluated by the Clausius-Clapeyron equation. The data measured in this study existed within the uncertainty range of the data from several previous studies.

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    DOI

• Zero Emissions, Low-Energy Water Production System Using Clathrate Hydrate: Engineering Design and Techno-Economic Assessment

  Meku Maruyama, Shigeo Tomura, Keita Yasuda, Ryo Ohmura

  Journal of Cleaner Production ( Elsevier )  383   135425   2023年01月 [ 査読有り ]

  掲載種別: 研究論文（学術雑誌）

  　概要を見る

  Seawater desalination via the crystallization using clathrate hydrate is a promising technology for displacing conventional desalination processes, yet the technology immaturity and poor cost performance are the issues to be resolved. In this study, conceptual designs of hydrate-based dual functional plant (desalination and salt production) utilizing the eutectic crystallization of hydrate and NaCl dihydrate have been presented on an industrial scale with the capacity of 24 m3/day. The conceptual design proposed in this study focuses on detailed and executive aspects, including the size of individual reactors, the selection of pumps, and the setting of operating temperature and pressure conditions. The process designs help meet these present demands on hydrate-based desalination and conform to the global standards of minimizing energy requirement and the disposal of environmental pollutants. Hydrate-based plant was designed as a novel Zero Liquid Discharge (ZLD) process to produce potable water and salt simultaneously, with the recovery ratio of pure water from seawater achieving 95%. The design-based cost estimation showed that the annual operating cost is estimated US$2.29/m3 for cyclopentane-hydrate-based plant and US$3.64/m3 for CO2-hydrate-based plant. The results suggest that the hydrate-based plants will bring gross profit comparable to the reported ZLD plants; that is, the gross profit will achieve US$20 per 1 m3 of water production. In addition to these two improvements over the existing plants, the hydrate-based process designs also exhibit favorable energy requirement compared to the eutectic system of ice. This design-based study may contribute to the promotion of additional construction of hydrate-based process unit to the existing reverse osmosis plant or even the new construction of hydrate-based desalination plant worldwide.

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    DOI

• Phase Equilibrium Conditions in Cyclopentane Hydrate Forming Systems Coexisting with Sodium Chloride Aqueous Solution under Atmospheric Pressure and Vacuum Condition

  Keitatsu Kamochi, Ayushman Tripathi, Masanao Taoka, Ryo Ohmura, Keita Yasuda

  The Journal of Chemical Thermodynamics ( Elsevier )  175   106886   2022年12月 [ 査読有り ]

  掲載種別: 研究論文（学術雑誌）

  関連する研究費コード: 19K14911, 22K03948

  　概要を見る

  The equilibrium condition measurements were performed in the cyclopentane clathrate hydrate forming systems coexisting with sodium chloride as a technological basis for the development of seawater desalination technology using clathrate hydrates. The experiments were performed in the system under vacuum condition in addition to the system under atmospheric pressure. The equilibrium conditions in the system under the vacuum condition are essential to accurately construct the phase diagram in the cyclopentane clathrate hydrate forming system without the effects of the surrounding air. The equilibrated phases were sodium chloride aqueous solution + cyclopentane clathrate hydrate + liquid cyclopentane + vapor cyclopentane in the system under the vacuum condition. The concentration of sodium chloride investigated in this study, wNaCl, was 0 ≤ wNaCl ≤ 0.210 in mass fraction. The equilibrium temperature in both systems decreased with increasing wNaCl. The equilibrium temperature at a fixed concentration of sodium chloride under the vacuum condition was lower than that under the atmospheric pressure. It was attributed to the compression by the atmospheric pressure in addition to the incorporation of molecules constituting the atmospheric air.

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• Development of Dual Functional Methodology for Seawater Desalination and Salt Manufacture by Carbon Dioxide Hydrate Formation

  Akari Gibo, Seiya Nakao, Sayaka Shiraishi, Satoshi Takeya, Shigeo Tomura, Ryo Ohmura, Keita Yasuda

  Desalination ( Elsevier )  539   115937   2022年10月 [ 査読有り ]

  掲載種別: 研究論文（学術雑誌）

  関連する研究費コード: 19K14911, 22K03948

  　概要を見る

  Clathrate-hydrate-based seawater desalination is a novel technology that is performed by reaction between seawater and guest compounds to obtain fresh water. This study proposed a dual functional methodology for seawater desalination and salt manufacture by using carbon dioxide clathrate hydrate. In this methodology, the clathrate hydrate formation continues until the concentration of electrolytes in unreacted brine reaches the saturated solubility for the salt precipitation. The visual observation of the clathrate hydrate formation and the salt precipitation coupled with the analysis utilizing the powder X-ray diffraction (PXRD) technique was implemented to demonstrate the methodology. The carbon dioxide clathrate hydrate formation was first performed with sodium chloride aqueous solution. The carbon dioxide clathrate hydrate crystals floated on high salinity water. This experiment was followed by the occurrence of the sodium chloride dihydrate precipitation upon the carbon dioxide clathrate hydrate formation. The formed compounds, carbon dioxide clathrate hydrate and sodium chloride dihydrate, were identified by PXRD analysis. The mass fraction of the compounds was also determined by PXRD.

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    DOI

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• Phase Equilibrium Conditions in Cyclopentane Clathrate Hydrate Forming Systems Coexisting with Sodium Chloride Aqueous Solutions

  Toshikazu Sasaki, Keitatsu Kamochi, Ayushman Tripathi, Masanao Taoka, Ryo Ohmura, Keita Yasuda

  The 12th International Conference on Separation Science and Technology     109   2023年11月  [査読有り]

   

• Relative Density of Carbon Dioxide Clathrate Hydrate and Sodium Chloride Aqueous Solution: Implications for Desalination Processes

  Shun Tsunekawa, Akari Gibo, Toshiyuki Tanaka, Sayaka Shiraishi, Ryo Ohmura, Keita Yasuda

  The 12th International Conference on Separation Science and Technology     109   2023年11月  [査読有り]

   

• Eutectic Conditions of Carbon Dioxide Clathrate Hydrate and Sodium Chloride Dihydrate for Desalination and Salt Production

  Hideya Suzuki, Akari Gibo, Seiya Nakao, Ryo Ohmura, Keita Yasuda

  The 12th International Conference on Separation Science and Technology     109   2023年11月  [査読有り]

   

• 研究室配属学生を対象とした演習科目における海水淡水化/製塩技術についての学術論文再現実験

  安田 啓太

  日本機械学会 2023年度年次大会     2023年09月  [査読有り]

   

• Laboratory Experiments Utilizing Clathrate Hydrates as Educational Materials

  Keita Yasuda, Izuru Senaha

  10th International Conference on Gas Hydrates     109   2023年07月  [査読有り]

   

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• ハイドレート法による海水淡水化と製塩および石膏回収のゼロ・エミッション技術

  基盤研究(C)

  課題番号: 22K03948

  研究期間: 2022年04月  -  2025年03月 

  代表者: 安田　啓太 

  直接経費: 3,300,000（円）  間接経費: 990,000（円）  金額合計: 4,290,000（円）

• クラスレートハイドレート法による海水淡水化/製塩ハイブリッドシステムの開発

  若手研究

  課題番号: 19K14911

  研究期間: 2019年04月  -  2021年03月 

  代表者: 安田　啓太 

  直接経費: 3,300,000（円）  間接経費: 990,000（円）  金額合計: 4,290,000（円）

• クラスレートハイドレート法による海水淡水化技術の開発

  若手研究(B)

  課題番号: 17K14604

  研究期間: 2017年04月  -  2019年03月 

  代表者: 安田　啓太 

  直接経費: 3,300,000（円）  間接経費: 990,000（円）  金額合計: 4,290,000（円）

• 氷点下温度域におけるクラスレート水和物　－相平衡条件測定と結晶構造解析ー

  特別研究員奨励費

  課題番号: 10J03623

  研究期間: 2010年04月  -  2012年03月 

  代表者: 安田　啓太 

  直接経費: 1,400,000（円）  間接経費: 0（円）  金額合計: 1,400,000（円）

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