纳米石墨颗粒对气体水合物生成诱导时间的影响

Effect of graphite nanoparticles on induction time of gas hydrate formation

分析和比较了纯水及浓度为0.4%的纳米石墨悬浮液体系中的CO2水合物生成过程。采用观察法测定了二种溶液体系在不同温度和压力条件下的水合物生成诱导时间,并研究了其随温度、压力的变化规律。结果表明,纳米石墨颗粒的引入能够加快体系的传热效率及成核速率,较大程度减少水合物生成的诱导时间,同等条件下,相较于纯水体系诱导时间平均下降了80.6%。此外,二种体系中水合物生成的诱导时间随着温度及压力的升高均分别呈增大和减少的趋势。然而,纳米石墨悬浮液体系中的水合物生成诱导时间受温压的变化影响较小。因此,纳米颗粒能够加速水合物的成核过程,且鉴于其巨大的比表面对传质过程的影响,实验结果也从侧面证明了水合物的成核速率主要受气液传质过程控制的结论。

The processes of CO2 hydrate formation in the pure water and the aqueous suspension containing graphite nanoparticles of 0.4% by mass were studied experimentally. The induction times of hydrate formation which occurred in two kinds of solution under different conditions of temperature and pressure were determined by observational method, and the rules of temperature and pressure affecting the induction time were investigated. The result showed that in presence of graphite nanoparticles,the efficiency of heat transfer and the rate of nucleation increased, and the induction time of hydrate formation decreased sharply by an average of 80.6%. In addition, the induction time of hydrate formation increased with temperature and decreased with pressure.However, in the aqueous suspension containing graphite nanoparticles, the induction time of hydrate formation had smaller change with pressure and temperature. Thus, graphite nanoparticles had a positive effect on hydrate formation. Besides, the conclusion of the rate of hydrate nucleation is mainly controlled by gas-liquid mass transfer was proved by the fact that the great surface area of graphite nanoparticles could accelerate the mass transfer.