联用型水合物促进剂对甲烷水合物生成过程的影响规律研究

Study on influence of combined hydrate promoter on formation process of methane hydrate

水合物较低的生成动力学速率和较高的相平衡条件是困扰水合物技术工业化应用的主要原因。研究了热力学促进剂(四丁基溴化铵(TBAB))和动力学促进剂(十二烷基硫酸钠(SDS)、十二烷基苯磺酸钠(SDBS))联用时对甲烷水合物生成热力学和动力学的促进行为,重点考察了3种促进剂质量比、联用型水合物促进剂质量分数和初始实验温度等因素对联用型水合物促进剂性能的影响。结果表明,将SDS、SDBS和TBAB以质量比2:1:1联用时,对甲烷水合物生成热力学和动力学均具有良好的促进作用,可有效降低甲烷水合物相平衡条件;适宜的联用型水合物促进剂质量分数为0.05%~0.30%,其中质量分数为0.10%时,诱导时间为75 s;降低初始实验温度可增加甲烷水合物生成的反应推动力,有利于快速成核与生长,当初始实验温度为276.15 K时,储气量高达170 mL/mL(1 mL水储存170 mL气体)。此外,联用型水合物促进剂的核心组分为离子型表面活性剂,在机械搅拌作用下体系会产生大量气泡,加快气液传质速率,因此甲烷水合物颗粒最初在界面气泡处出现,随后呈现气相和液相双向生长趋势,进而快速充满反应釜,有利于对甲烷等气体小分子的储存。

The low formation kinetic rate and the high phase equilibrium condition of hydrate are the main reasons that hinder the industrial application of hydrate technology.In this paper,the thermodynamic and kinetic promoting behavior of methane hydrate formation was studied while thermodynamic promoter(tetrabutylammonium bromide(TBAB))and kinetic promoters(lauryl sodium sulfate(SDS)and sodium dodecylbenzene sulfonate(SDBS))were used together.The effects of mass ratio of three promoters,mass fraction of combined hydrate promoter and initial experimental temperature on the properties of combined hydrate promoter were investigated.The results show that the combination of SDS,SDBS and TBAB at mass ratio of 2:1:1 can promote the thermodynamics and kinetics of methane hydrate formation,and effectively reduce the condition of methane hydrate phase equilibrium.The optimum mass fraction of combined hydrate promoter is 0.05%to 0.30%,and the induction time reaches 75 s when the concentration is 0.30%.Reducing the initial experimental temperature can increase the reaction impetus of methane hydrate formation,which is conducive to rapid nucleation and growth.When the initial experimental temperature is 276.15 K,the gas storage capacity is as high as 170 mL/mL(170 mL of gas stored in 1 mL of water).In addition,the core component of combined hydrate promoter is ionic surfactants.Under the condition of mechanical stirring,a large number of bubbles will generate in the system to enhance the gas-liquid mass transfer rate.Therefore,methane hydrate particles initially appear at the interface bubbles,and then show a trend of gas phase and liquid phase bidirectional growth,and thus quickly fill the reactor,which is conducive to the storage of small gas molecules such as methane.