多元体系水合物降压分解实验研究

发布时间：2018-06-08 02:11

  本文选题：多元体系 + 水合物　； 参考：《吉林大学》2017年硕士论文

【摘要】：由于人类社会和经济的发展长时间依靠传统化石能源,目前,全球范围内的气候变化,资源匮乏和环境污染等问题日益加剧。天然气水合物(简称水合物)作为一种清洁高效的非常规能源正逐渐成为全世界的研究热点。自然界中的水合物按成因气类型可分为生物成因的甲烷水合物和热解成因的多元体系水合物。多元体系水合物因组成复杂,结构多样,其分解特性与常规甲烷水合物有很大差异。此外,在常规的水合物开采方法中,降压法被认为是最经济可行的开采方法。因此,有必要开展多元体系水合物降压分解特性的研究。首先利用透明搅拌釜开展了CH_4-C_2H_6、CH_4-C_3H_8、C_2H_6-C_3H_8和CH_4-C_2H_6-C_3H_8四种组分水合物的形成实验。实验中观察到搅拌下多元体系水合物的形成由溶解气形成和气液界面形成两种机制共同作用。CH_4-C_2H_6、CH_4-C_3H_8和CH_4-C_2H_6-C_3H_8水合物形成时,气相中各组分表现出明显的分离效应,而C_2H_6-C_3H_8水合物形成时,气相中各组分相对含量逐渐靠近。多元体系水合物形成时按照C_3H_8,C_2H_6和CH_4的顺序先后填充到水合物的笼型结构中。其次,分别利用透明搅拌釜和静态反应釜开展了二元(CH_4-C_2H_6、CH_4-C_3H_8和C_2H_6-C_3H_8)和三元(CH_4-C_2H_6-C_3H_8)水合物的降压分解实验,分别研究了温度、压力和体系类型对降压分解特性的影响。多元体系水合物在高压分解时,因水合物的笼型结构填充的气体不同而具有不同的稳定性,水合物的分解存在多个阶段,C_2H_6和C_3H_8分别存在“短暂滞留”和“长期滞留”的现象,该现象在静态体系、低温、高压和各组分结构稳定性差异较大时更加明显。因上述组分滞留现象的存在,使分解区滞留的水合物形成一层水合物膜包裹在内部水合物颗粒的周围,阻碍内部水合物的分解,使体系进入“亚稳态”,形成部分分解的现象。最后,研究了多元体系水合物在冰点下的分解特性。实验结果表明各类型水合物在冰点下均存在部分分解现象,且在-4℃时这种现象较-1℃更明显,该现象源于冰点下水合物自保护效应的冰膜。此外,冰膜不断增厚,C_3H_8的组分滞留现象逐渐显现出来,且-4℃较-1℃更早出现,而实验条件下C_2H_6未出现明显的组分滞留现象。
[Abstract]:Because the development of human society and economy depends on the traditional fossil energy for a long time, the problems of climate change, resource scarcity and environmental pollution in the world are becoming more and more serious. As a kind of clean and efficient unconventional energy, natural gas hydrate (gas hydrate) has gradually become a research hotspot all over the world. The hydrates in nature can be divided into biogenic methane hydrates and pyrolytic multicomponent hydrates according to the type of gas. Because of the complex composition and diverse structure, the decomposition characteristics of the multicomponent hydrate are quite different from those of the conventional methane hydrate. In addition, depressurization is considered to be the most economical and feasible method in conventional hydrate mining. Therefore, it is necessary to study the decomposing characteristics of hydrates. At first, the Ch _ S _ 4-C _ 2H _ 6C _ _ _ It was observed in the experiment that the formation of hydrates in the multicomponent system under agitation combined the formation of dissolved gas and the formation of gas-liquid interface. CH4-C2H2H6-C3H8, and the components in the gas phase showed an obvious separation effect when they were formed, and when the C _ 2H _ 6-C _ 3H _ 8 hydrate was formed, the number of components in the gas phase showed a distinct separation effect when they were formed, and the number of C _ 2H _ 6-C _ 3H _ (8) was compared with that of C _ 2H _ 6-C _ 3H _ 8. The relative content of each component in the gas phase is gradually approaching. When the hydrates were formed in the multicomponent system, the structure of the hydrates was filled into the cage structure of the hydrates successively according to the order of C _ S _ 3H _ 8H _ (8) and C _ s _ 2H _ S _ 6 and Ch _ s _ 4. Secondly, by using a transparent stirred tank and a static reactor, respectively, the depressurization experiments of binary CHS _ 4-C _ 2H _ 2S _ T _ 6CH4-C _ 3H _ S _ 8 and C _ 2H _ 6-C _ 3H _ 3H _ 8 and S _ 2H _ 4-C _ 2C _ 3H _ 8) hydrate were carried out, respectively, and the effects of temperature, pressure and the type of system on the characteristics of the decompression were studied respectively. When the hydrates are decomposed at high pressure, the hydrates have different stability because of the different gas filled with the cage structure of the hydrates. There are many stages of decomposition of hydrates, such as "short stay" and "long stay" in C _ 2H _ 6 and C _ S _ 3H _ 8, respectively, when the hydrates are decomposed at high pressure. This phenomenon is more obvious in static system, low temperature, high pressure and structural stability of each component. Due to the existence of the retention phenomenon of the components mentioned above, the hydrates in the decomposition zone form a layer of hydrate membrane around the inner hydrate particles, which hinders the decomposition of the internal hydrates and makes the system enter into the "metastable state" and form the phenomenon of partial decomposition. Finally, the decomposition characteristics of hydrates at freezing point were studied. The experimental results show that all types of hydrates are partially decomposed at freezing point, and this phenomenon is more obvious at -4 鈩，

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