| Project/Area Number |
16360483
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Energy engineering
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| Research Institution | National Maritime Research Institute |
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Principal Investigator |
SHIROTA Hideyuki National Maritime Research Institute, Ocean Engineering Department, Senior Researcher, 海洋部門深海技術研究グループ, 主任研究員 (40344238)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAJIMA Yasuharu National Maritime Research Institute, Energy and Environment Assessment Department, Senior Researcher, エネルギー・環境評価部門環境影響評価研究グループ, 主任研究員 (30344237)
AYA Izuo National Maritime Research Institute, Osaka Branch (10415812)
YAMANE Kenji National Maritime Research Institute, Osaka Branch, Vice Director, 大阪支所, 副支所長 (10358393)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥9,200,000 (Direct Cost: ¥9,200,000)
Fiscal Year 2005: ¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2004: ¥6,100,000 (Direct Cost: ¥6,100,000)
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| Keywords | hydrate / natural gas / sea-borne transport / self-preservation / dissociation / liquefied natural gas (LNG) |
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| Research Abstract |
(a) We first selected two kinds of multi-component gases as simulated natural gas whose component was close to that of actual natural gas, such as a 98:2 CH4:C2H6 mixture and a 94.5:5:0.5 CH4:C2H6:C3H8 mixture. Then, we made natural gas hydrate samples from the multi-component gas and small ice particles with the particle size controlled and with no pelletization processed, and experimentally examined its dissociation behaviors (self-preservation property). As a result, we confirmed that temperature change did not have much influence upon the self-preservation of the multi-component natural gas hydrate for the temperature range from -20 degrees C to -5 degrees C, and a difference in hydrate structure (structure-I or structure-II) did not have influence significantly upon it.
(b) Our experimental results in the present research agreed with the experimental data for natural gas hydrate pellets by Takahashi et al. at Mitsui Engineering & Shipbuilding Co., Ltd., in both that the natural gas hydrate (which includes structure-II hydrate) also had the self-preservation property in the same way as CH4 hydrate (which forms structure-I) and that change of natural gas composition did hardly have influence upon the self-preservation of natural gas hydrate. We can conclude that these results will support validity and feasibility of the concept of applying the self-preservation of gas hydrate to natural gas sea-borne transport.
(c) We compared the results in the present research with several dissociation data obtained in different conditions, and examined the mechanism of self-preservation. Then, we pointed out that several factors (difference in manufacturing method of hydrate samples, difference in thermal history of samples, influence of mechanical compression, and influence of ice content in samples) may be possibly important for elucidation of the mechanism.
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