Abstract:

With the deepening research on gas hydrates in carbon capture and oil-gas transportation, the study to their phase equilibrium is significantly important. The gas forming hydrates can be either pure components or mixtures. Hydrate formation involves three- or four-phase equilibria, including I-H-V (ice-hydrate-vapor), L_w-H-V (liquid water-hydrate-vapor), L_w-H-L_HC (liquid water-hydrate-liquid hydrocarbon), and L_w-H-V-L_HC (liquid water-hydrate-vapor-liquid hydrocarbon). The phase diagrams of hydrates formed by different gas compositions exhibit notable differences, particularly in the number of four-phase points. This paper focuses on methane, nitrogen, carbon dioxide, propane and natural gas mixture systems, discussing numerical calculation methods for hydrate phase diagrams containing one or two four-phase points and four-phase lines. Numerical simulations are conducted using the independently developed SimTech Simulator, and the results are compared with those from the commercial software Pro/Ⅱ, validating the reliability of the Simulator.

Key words: gas hydrate, phase diagram, four-phase point, numerical simulation, phase equilibrium

摘要：

随着气体水合物在碳捕集与在油气运输中的相关研究不断深入，研究其相平衡具有重要意义。形成水合物的气体可以是纯组分，也可以是混合物。水合物的形成伴随着三相或者四相平衡，包括I-H-V（冰-水合物-气相）、L_w-H-V（液态水-水合物-气相）、L_w-H-L_HC（水-水合物-液态烃）以及L_w-H-V-L_HC（液态水-水合物-气相-液态烃）的相平衡。不同气体组分形成的水合物相图有很大的差别，主要体现在四相点的个数。本文以甲烷、氮气、二氧化碳、丙烷等和天然气混合物体系为例，分别讨论了含一个、两个四相点及四相线的水合物相图的数值计算方法。利用自主研发的SimTech Simulator进行了数值模拟，并与商业软件Pro/Ⅱ的计算结果进行了对比，验证了其可靠性。

关键词: 气体水合物, 相图, 四相点, 数值模拟, 相平衡