含盐体系二氧化碳水合物的生成与分解特性

Characteristics of CO_2 Hydrates Formation and Decomposition in Saline Solutions

在小型水合物反应装置上对含盐体系CO2水合物的相平衡特性进行了实验研究,并探讨盐度及pH值对CO2水合物的生成和分解特性的影响。结果表明,与纯水相比,含盐体系中CO2水合物的相平衡条件要求更高,CO2水合物的稳定存在区域缩小,且盐度越大越明显;盐类物质对CO2水合物的生成有抑制作用,增加了水合物的成核诱导时间,降低了水合物的生成量;pH值较高的含盐体系不利于CO2水合物的成核和生成;CO2水合物的分解速度随着温度的升高而增大,而盐度对水合物分解的影响并不明显。

CO2 hydrates can be used for long term storage of CO2 in the deep ocean. The characteristics of CO2 hydrate phase equilibrium in saline solutions with different salinities were investigated. A series of experiments were carried out in a small scale high-pressure reactor using constant volume method. The effects of salinity and pH on CO2 hydrate formation and decomposition were discussed. The experimental results indicate that phase equilibrium conditions of CO2 hydrate are greatly restricted in saline solutions compared to that in pure water. Since salt components inhibit CO2 hydrate formation, higher initial salinity will lead to longer induction time and less hydrate formation. The induction time of CO2 hydrates formation in 4.5% salinity solution is 6 times longer than that in pure water. Saline solution with higher pH is unfavorable to CO2 hydrate nucleation and formation. Decomposition rate of CO2 hydrates is accelerated with the increase of temperature. However, salinity has no significant impact on CO2 hydrate decomposition.