Span20等化学添加剂对甲烷水合物生成过程的影响

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	Span20等化学添加剂对甲烷水合物生成过程的影响
其他题名	Effect of Span20 and Some Chemical Additives on Methane Hydrate Formation Proceed
	杜建伟
导师	樊栓狮
	2008-06-04
学位授予单位	中国科学院广州能源研究所
学位授予地点	广州能源研究所
学位名称	硕士
关键词	甲烷水合物表面活性剂化学添加剂促进作用生成动力学形成机理
摘要	天然气水合物是不仅是一种清洁能源，而且与水合物相关的新技术受到越来越多的重视。已有的研究表明表面活性剂等化学添加剂添加剂对天然气水合物形成过程有重要的影响，可有效促进水合反应，提高储气率。本文在天然气水合物储气实验台上，利用带磁力搅拌的144ml高压反应釜，采用定压法，在温度为274.15±0.10K，压力为8.30±0.10MPa条件下，从诱导时间、生成速率和储气密度等方面研究了非离子表面活性剂失水山梨醇单月桂酸酯（Span20）等化学添加剂对甲烷水合物生成动力学的影响。实验研究表明：（1）对于非离子表面活性剂Span20，其2000ppm水溶液中甲烷水合物生成的诱导时间最短，为53-167分钟；而在4000ppm下的甲烷水合物生成速率最大，是纯水的10倍以上；同时其储气密度最大，达到145.2 V/V。（2）非离子表面活性剂Span80能有效促进甲烷水合物的生成：提高生成速率、缩短诱导时间并增加储气密度。200ppmSpan80水溶液平均进气速率为8.9ml/min，500ppmSpan 80水溶液平均进气速率为17.2ml/min，1000ppmSpan80水溶液平均进气速率为27.9ml/min均远远高于纯水中的进气速率；同时Span80水溶液在较短的时间内得到较高的甲烷水合物储气密度，2小时内甲烷水合物在Span80浓度为200ppm处最终储气密度为161 V/V，500ppm为152 V/V，1000ppm储气密度达到167V/V，均远远高于同样时间内纯水中14.49 V/V的储气密度；同时随着Span80水溶液浓度的增加, 甲烷水合物生成的诱导时间缩短。浓度为200ppm体系, 水合物生成的诱导时间高达217分钟, 而浓度为1000ppm的体系水合物生成的诱导时间只有23分钟，诱导时间大大缩短。（3）实验研究了多种其它表面活性剂和化学添加剂对甲烷水合物生成的影响。结果表明，环己酮、碳纳米管、十六烷基三甲基溴化铵（CTAB）、β-环糊精以及氯化铵对甲烷水合物生成没有明显促进作用；对甲烷水合物生成速率有明显促进作用的乙醇胺、四辛基溴化铵、3A分子筛和5A分子筛其最终储气密度不高，仅为40-50V/V左右，远低于Span 20、Span 80以及SDS。（4）通过分析Span20、CTAB和SDS等的分子结构，对表面活性剂促进甲烷水合物生成机理进行了分析，认为化学添加剂的分子结构是影响甲烷水合物生成动力学的主要原因之一。 Span20分子中带有两个羟基的类四氢呋喃结构的诱导作用以及假六元环的模版作用共同促进了甲烷水合物的形成。
其他摘要	Gas hydrates have attracted much attention recently, not only as a new natural energy resource but also as a new means for natural gas storage and transport.. Researchers have found one of the most effective methods for the reduction of power consumption in the hydrate formation process would be acceleration of the hydrate formation rates by using surfactants. Surfactants are substances that when they present even at very low concentrations, have the ability to significantly alter the surface or interfacial free energies. Therefore, surfactants have a direct effect on the hydrate formation process. Experiments on the effect of non-ionic surfactant sorbitan monododecanoate (Span 20) and some chemical additives on induction time, formation rate and gas storage density were conducted during methane hydrate formation in a high pressure reactor with a magnetic stir at 274.15±0.10K, 8.30±0.10MPa. The major experimental and theorital results are briefly shown as follows: （1） The results show that the induction time with 2000ppm Span 20 was shortest: 53-167 minutes and a maximum formation rate was obtained with 4000ppm Span 20, about 10 times the rate of pure water. Moreover, at 4000ppm Span 20 also had the largest gas storage density of 145.2 V/V. On the basis of analysis on the Span 20 structure, the mechanism of surfactants promoting methane hydrate formation was investigated. It appears that the induction effect of tetrahydrofuranoid with two hydroxyls together with the template effect of the false hexahydroxy cycle may promote methane hydrate formation. （2） Experiments on the effect of Span 80 on induction time, formation rate and gas storage density were conducted during methane hydrate formation.The results show that the induction time with 200ppm Span 80 was 217 minutes and 1000ppm Span 80 with 1000ppm was shortest: 23 minutes and a maximum formation rate was obtained with 1000ppm Span 80: 27.9ml/min. Moreover, at 1000ppm Span 80 also had the largest gas storage density of 167V/V. （3） Besides We examined their effects of several other surfactants and chemical additives on methane hydrate formation experimentally. The results indicate that cyclohexanone、Carbon nanotube、Hexadecyl trimethyl ammonium bromide（CTAB）、β-Cyclodextrin and Ammonium chloride have unconspicuous promotion effect on methane hydrate formation；and for Ethanolamine 、Tetraoctylammonium bromide、3A/5A Molecule Sieve which can promote methane hydrate have much lower gas storage density than Span 20、Span 80 and SDS （4） Although a detailed mechanism of the acceleration effect of such surfactants has not been elucidated, it can be speculated that a cluster-promoter structure could be formed in water phase and the formed nuclei in the presence of surfactants should have a higher surface area per unit volume of the system, which would enhance the uptake rate of the guest molecules from the gas phase.
页数	64
语种	中文
文献类型	学位论文
条目标识符	http://ir.giec.ac.cn/handle/344007/5776
专题	中国科学院广州能源研究所
推荐引用方式 GB/T 7714	杜建伟. Span20等化学添加剂对甲烷水合物生成过程的影响[D]. 广州能源研究所. 中国科学院广州能源研究所,2008.

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