Nucleation rate of gas hydrates

气体水合物成核率

• 批准号: RGPIN-2019-04241
• 负责人: MAEDA, NOBUO
• 金额: $ 2.04万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=749087
• 关键词: Nucleation; rate; gas; hydrates

Ice floats on liquid water because it is less dense than water. The hollow structure of ice can accommodate small gas molecules as guests in its cavities under low temperature - high pressure conditions. These crystalline solids in which guest molecules are trapped by water molecules are called gas hydrates. Gas hydrates have potential applications in gas storage, carbon dioxide sequestration, gas separation and desalination. Gas hydrates also form the largest unconventional natural gas resources on earth. Formation of gas hydrates is a first-order phase transition that starts with nucleation. Nucleation refers to the formation of a thermodynamically stable phase in the metastable parent phase and the process requires surmounting of an activation energy barrier. This activation process is intrinsically stochastic and is best described in terms of probability distributions. One would wish to facilitate nucleation when the formation of gas hydrate is desirable and suppress nucleation when it is undesirable. Understanding of nucleation is of interest to many in chemical and petroleum industry, as nucleation, while a benefit in many chemical processes, is a concern in flow assurance. In particular, there is interest in understanding the nucleation process to more effectively, cost-efficiently and safely prevent nucleation of gas hydrates in pipelines. A primary difficulty in the investigation of gas hydrate nucleation has been the inability of researchers to compare nucleation rates of gas hydrates across various systems of different scales and complexity, which in turn has been limiting the ability of researchers to study the nucleation process itself. Nucleation rate is equivalent to nucleation probability density per unit system size and per unit time, and allows scientifically meaningful comparisons of nucleation processes between various systems. Based on the cutting-edge technology we have been developing, we propose to establish a robust technology that can reliably determine the nucleation rates of a range of gas hydrates. We also propose to create a database of nucleation rates of gas hydrates under a broad range of conditions that start from the simplest case of single-component gas hydrates in pure water to progressively complex systems that involve mixed gas hydrates, solid walls and a range of chemicals. Systematic determination of nucleation rates will allow identification of physicochemical factors that have the greatest impact on nucleation of gas hydrates.

冰漂浮在液态水上，因为液态水的密度比水小。冰的中空结构可以在低温高压条件下容纳小气体分子。这些客体分子被水分子捕获的结晶固体被称为天然气水合物。天然气水合物在天然气储存、二氧化碳封存、气体分离和海水淡化方面具有潜在的应用前景。天然气水合物也是地球上最大的非常规天然气资源。天然气水合物的形成是从成核开始的一级相变。成核是指在亚稳的母相中形成一个热力学稳定的相，这个过程需要克服一个活化能垒。这个激活过程本质上是随机的，最好用概率分布来描述。人们希望在希望形成天然气水合物时促进成核，而在不希望形成水合物时抑制成核。对成核的理解对化学和石油工业的许多人都很感兴趣，因为成核虽然在许多化学过程中都有好处，但在流动保证中却是一个问题。特别是，人们有兴趣了解成核过程，以更有效、更经济、更安全地防止管道中天然气水合物成核。研究天然气水合物成核的一个主要困难是研究人员无法比较不同规模和复杂程度的各种系统中天然气水合物的成核速率，这反过来又限制了研究人员研究成核过程本身的能力。成核速率相当于单位系统尺寸和单位时间的成核概率密度，可以对不同系统之间的成核过程进行有科学意义的比较。基于我们正在开发的尖端技术，我们建议建立一种可靠的技术，可以可靠地确定一系列天然气水合物的成核速率。我们还建议在广泛的条件下建立一个天然气水合物成核速率的数据库，从最简单的纯水单组分天然气水合物开始，到涉及混合天然气水合物、固体壁和一系列化学物质的逐渐复杂的系统。系统地测定成核速率将有助于确定对天然气水合物成核影响最大的物理化学因素。