水-气体系生成水合物的缩泡动力学模型

在对海下沉积层中水合物的生成机理、水合物的生成实验现象和已有模型分析的基础上,提出了一种水-气体系水合物生成的缩泡动力学模型,认为溶液中气体首先形成气泡,然后和水反应形成水合物.模型以水合物体积的变化来表示水合物的生成速率,避免了单纯以化学反应过程或结晶过程表达水合物生成速率的缺陷,因此能够准确地表达水合物的生成过程.研究结果表明,在不同初始条件下的计算结果与文献结论一致,不同气体和不同传质系数条件下的计算结果经实验验证正确,甲烷、乙烷及混合气在相同初始条件下,乙烷水合物的层厚度大于甲烷和混合气体水合物的层厚度.在传质系数较大时,水合物的层厚度增加速度也明显较大,因此符合表面活性剂能够加速水合物生成的机理.

Kinetic Model of Shrinking-Bubble for Gas Hydrate Formed from Gas and Water

A novel kinetic model of shrinking-bubble for hydrate formation in solution was proposed through the analysis of the hydrate formation mechanism in sediment and the experimental appearances. It was considered that the bubbles are formed firstly on the gas-liquid interface, and then hydrate is generated on the sphere surface of the bubbles. In the model, the hydrate formation rate is confirmed to coincide with the expanding speed of the hydrate volume in order to describe the hydrate formation process more accurately, and the model also breaks off the limitations of just describing hydrate formation as the reaction process or the crystallization process. Simulation calculations were carried out with various initial conditions, gas components, and mass transfer coefficients. It is shown that the results coincide with the experimental and literature records well. It is also found that the layer thickness of ethane hydrate is thicker than that of methane hydrate and their mixture, and the increasing acceleration of the result hydrate layer with high mass transfer coefficients is bigger than that with lower mass transfer coefficients, too. These phenomena correspond with the promotion mechanism of the surfactant well.