外部剪切对天然气水合物生成影响的实验研究

Study on the Influence of External Shear Effect on the Formation of Natural Gas Hydrate

未来对于天然气的运输、调峰以及储存等领域,天然气水合物都会起到重要的作用,天然气水合物应用技术的关键在于天然气水合物的快速及大量生成。因此,对天然气水合物生成过程做进一步研究很有必要。目前,人们主要研究了温差、压力扰动、降温速度等因素对水合物生成过程的影响作用,但基于剪切作用对水合物生成的研究还不够深入。因此,实验研究了在含动力学抑制(PVPK90)的条件下,有无剪切作用对CH4水合物生成量的影响。结果表明:剪切作用会增加天然气与水分子的碰撞几率,促进水合物晶核的生成和成长,但同时会阻碍水合物晶核微粒的聚结作用。一定体积的溶液下,形成的水合物晶核微粒数量受到限制。在剪切作用被消除后,内壁上会聚结并附着大量水合物晶核,并为新的水合物晶核形成提供空间。因此,使甲烷水合物晶核的形成过程与聚结过程在两个连通的容器中同时进行,则水合物的形成过程不会被阻止。更换水合物晶核聚结的容器,则工业上能够大量生成用于储存运输天然气的水合物。

In the future, natural gas hydrate will play an important role in the transportation, peak regulation and storage of natural gas. The key of the application technology of gas hydrate lies in the rapid and large production of gas hydrate. Therefore, it is necessary to further study the formation process of natural gas hydrate. At present, the effect of temperature difference, pressure disturbance and cooling rate on hydrate formation are mainly studied, but the study on hydrate formation based on shear action is not enough. Therefore, the effect of shear and non shearing on the formation of CH4 hydrate was studied under the condition of kinetic inhibition(PVPK90). The results showed that the shear effect increased the collision probability of natural gas and water molecules to promote the formation and growth of the nucleus of hydrate, but at the same time hindered the coalescence of the nucleation particles of the hydrate. The amount of hydrate nucleated particles was limited under certain volume of solution. After shearing was eliminated, a large number of hydrate nuclei converged and attached to the inner wall, providing the space for the formation of new hydrate. Therefore, the formation process of methane hydrate and the coalescence process were carried out in two connected containers simultaneously, and the formation process of hydrate was not prevented. Replacement of containers for hydrate nucleation coalescence can produce large quantities of hydrate for storage and transportation of natural gas in industry.