Gas hydrate is generally formed at comparatively high pressure or low temperature. For instance, methane hydrate at 0 deg C remains stable (does not dissociate) above about 2.7 MPa, and methane hydrate at atmospheric pressure (0.1 MPa) remains stable below about -80C. But, in recent years, some researchers reported that methane hydrate remains meta-stable even under some conditions outside its stability region. If the meta-stable (selfpreservation) property of gas hydrate can be utilized economically in addition to its high-density gas containing property, it is possible to store and transport stranded natural gas at higher temperature, compared to the conventional LNG (liquefied natural gas) method. The self-preservation property of either 'non-pelletized' or 'pelletized' hydrate has been gradually clarified so far. There is, however, a disparity among these data, and the reason for the disparity has not been still elucidated. In order to understand the 'genuine' self-preservation property of gas hydrate, we made gas hydrate samples from small ice particles and methane with hydrate particle size controlled and with no pelletization processed, and experimentally examined their self-preservation property at atmospheric pressure. The ice particle size for hydrate formation was controlled below 500p.m or less, and the temperature was ranged between -7 degC and -3 degC. As a result, we obtained the data in good agreement with those in the previous data, namely confirmed the data reproducibility. Next, we compared the present experimental results to our previous data obtained for methane hydrate pellets, which had been made by using the hydrate production and pelletization trial machines manufactured for research of high-speed mass production of natural gas hydrate pellets at Mitsui Engineering & Shipbuilding Co., Ltd. We pointed out that there was a considerable gap in these data, and that there was a possibility that we observed such the data gap mainly owing to the following factors: (1) the difference in manufacturing method of the hydrate samples, (2) the difference in thermal history of the samples, and (3) the influence of pelletization process.
Experimental study on self-preservation property of gas hydrate for natural gas sea-borne transport
Experimentelle Untersuchung über die Selbsterhaltungseigenschaft von Gashydrat für den Erdgas-Seetransport
2005
7 Seiten, 11 Bilder, 25 Quellen
Conference paper
Storage medium
English
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