表面活性剂在瓦斯水合物生成过程中的热力学作用

Thermodynamic effect of surfactant on gas hydrate formation

在实验研究基础上,结合表面活性剂水溶液中瓦斯水合物生成微观机理,提出了表面活性剂改变水合物生成热力学条件物理作用假说,认为表面活性剂胶束对溶于其中的气体分子和吸附于其周围的水分子的束缚作用,相当于降低了体系的温度.利用T40(0·001mol·L-1)、T40(0·002mol·L-1)、T40/T80(0·001mol·L-1)分别组成的3种气-液-煤-水合物反应体系实验测定了水合物生成时的相平衡参数,与同样温度和压力条件下相平衡计算值比较,结果表明,表面活性剂的加入有效地改变了水合物生成的热力学条件.例如,在T40/T80(0·001mol·L-1)实验体系中,当压力为22·67MPa时,水合物生成相平衡温度为22·6℃,比纯水中提高2·1℃.

A physical effect hypothesis based on the microscopic mechanism of gas hydrate formation in the surfactant solution is presented. The hypothesis assumes that the surfactant could alter the thermodynamic conditions of hydrate formation, that is to say, the effect of restriction of surfactant micelle on gas molecule dissolved in it and water molecule absorbed around it is equivalent to the reduction of system temperature. Phase equilibrium parameters of hydrate formation were measured in three different kinds of gas-liquid-coal-gas hydrate reaction systems composed of three different surfactant solutions （T40, 0.001 mol· L^-1 T40, 0. 002 mol·L^-1; T40/T80, 0. 001 mol· L^-l）, respectively. Comparison of the experiment data with the calculated value of the phase equilibrium theory in the same condition indicated that the thermodynamic conditions were changed evidently when the surfactant was added. For example, in the system with T40/T80 added, when the pressure was 22.67 MPa, the phase equilibrium temperature of hydrate formation could reach 22. 622, which was 2. 122 higher than that in pure water.