结晶法制备天然气水合物实验研究

由于天然气水合物的生成过程与盐溶液结晶过程极为相似，采用饱和溶液提供第二相晶种代替水合物晶核自发形成的方式，首次提出了基于饱和溶液结晶法制备天然气水合物的方法，实验研究了饱和Na2SO4溶液、饱和MgSO4溶液、饱和NH4HCO3溶液、饱和CuSO4溶液四种饱和溶液对天然气水合物生成速度及储气量的影响。结果表明：饱和Na2SO4溶液中天然气水合物生成速度较快，平均为去离子水中水合物生成速度的11.8倍，最大瞬时生成速度为去离子水的386倍，储气量为去离子水的11倍；饱和MgSO4溶液中水合物平均生成速度为去离子水的20倍，最大瞬时生成速度为去离子水的165倍，储气量为去离子水的7.2倍；饱和NH4HCO3溶液中水合物的平均生成速度为去离子水的7.8倍，储气量为去离子水的10倍，饱和CuSO4溶液中水合物平均生成速度为去离子水的8.6倍，储气量为去离子水的6.7倍。采用饱和溶液结晶法后可以实现高效制备天然气水合物，可为天然气以水合物的形式运输储存提供理论指导。

Experimental study on Preparation of natural gas hydrate by crystallization

In this paper, the saturated solution crystallization method is proposed to promote the formation of hydrate by means of the known similarities between the hydrate formation process and the crystallization process. In this method,adding the second phase crystals was used to replace the spontaneous formation of hydrate crystal nuclei to form hydrate.The effects of saturated Na_2SO_4, MgSO_4, NH_4HCO_3 and CuSO_4 solutions on the formation rates of natural gas hydrate and gas storage capacity were investigated. The results showed that the saturated solution had an influence on the hydrate formation process. Under the given experimental conditions, the saturated Na_2SO_4 solution showed a highest increase in the hydrate formation rate, and the average hydrate formation rate in its presence was 11.8 times higher than that obtained in the deionized water. Moreover, the largest formation rate of gas hydrates observed in the saturated Na_2SO_4 solution was 386 times bigger than that in the deionized water, and the gas storage capacity increased by 10 times. In addition, the average hydrate formation rate in the saturated Mg SO_4 solution was faster than that in water by 20 times. The largest formation rate of gas hydrates in the saturated MgSO_4 solution was 165 times faster than that obtained in the deionized water, and the gas storage capacity increased by 6.2 times. The saturated NH_4HCO_3 and saturated CuSO_4 solutions also influenced the formation process of hydrate. Therefore, the crystallization method of saturated solution can be used to achieve a highefficiency preparation of natural gas hydrates, which provides theoretical guidance for the storage of natural gas in the form of hydrate.