不同驱动力下瓦斯水合物生长过程Raman光谱特征

Raman Spectra Characteristics of Gas Hydrate Growth with Different Driving Forces

基于煤矿瓦斯(CH_4∶C_2H_6∶N_2=67.5∶22.5∶10)水合物相平衡曲线开展四种驱动力ΔP水合动力学实验,利用可见显微Raman光谱仪获取水合物生长过程光谱图,根据水合物相中C_2H_6 C—C键伸缩振动特征峰Raman位移确定了4组实验中水合物为sⅡ结构。基于van der Waals与Platteeuw模型获取瓦斯水合物生成过程中水合物相气体组分及水合指数变化规律。研究表明:驱动力的大小影响水合物的稳定性,随着驱动力的增加,CH_4相比C_2H_6逐渐占据更多的孔穴结构,CH_4在水合物相内比例增加,水合物稳定性越强;瓦斯中N_2,CH_4和C_2H_6进入水合物孔穴优先级可以通过分子与水合物孔穴的直径比进行确定,分析认为在sⅡ水合物结构中小孔穴CH_4优先级最高,大孔穴C_2H_6最高;基于瓦斯水合物稳定性,对水合物生长过程客体分子的物质传递规律进行描述,为瓦斯水合物的微观生长提供理论基础。

Based on the phase equilibrium line of coal mine gas（CH_4∶C_2H_6∶N_2=67.5∶22.5∶10）hydrate,hydration kinetics experiments with four different driving forces were worked out.The hydrate growth spectra were obtained by using microRaman spectroscopy.The hydrates in four experiments were sⅡtype according to the Raman shift of C_2H_6 C—C bond stretching vibration.The change laws of gas hydrate phase compositions and hydration numbers were obtained based on the model of van der Waals and Platteeuw.The results showed that the stability of hydrate was affected by driving force.When the driving force increased,the CH_4 occupied more cavities than C_2H_6, and the more proportion of CH_4 in hydrate phase,was the more stable the hydrate became.The priority levels entering hydrate cavities of N_2,CH_4 and C_2H_6 could be determined by using the diameter ratio of object molecular and hydrate cavities.Among these objects,the priority level of CH_4 was the highest for small cavities and C_2H_6 was the highest for large cavities.The description of the guest material transfer law of hydrate growth process based on gas hydrate stability provides a theoretical basis for gas hydrate micro-growth.