In this work, the effect of adding thermodynamic promoters tetra-n-butyl phosphonium bromide (TBPB) and tetrahydrofuran (THF) on the conditions of CO₂ gas hydrate formation is investigated. Considering that seawater is used for the formation of hydrate in large volume, the effect of NaCl as the dominant salt in saline water on the phase equilibrium of the CO₂ + TBPB system in the presence of THF is studied. Also, in order to predict the conditions of hydrate formation, the van der Waals–Plateau model has been used to model the hydrate phase equilibrium. The SRK equation of state has been used to check the gas phase. The e-NRTL model has been used to estimate the activity coefficient, and the model parameters for the system are presented under study. The results show that addition of NaCl (3% mass fraction) to the (TBPB + THF) aqueous solution changes the equilibrium conditions of CO₂ hydrate formation. It is observed that the hydrate pressure predicted by the provided model is in good agreement with the available experimental data on the CO₂ hydrate phase equilibrium in the presence of TBPB, THF, and NaCl. The model parameters are also estimated by using experimental data and the optimization method. The average absolute deviation for hydrate dissociation pressure is 3.23%.

中文翻译：

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CO2 + TBPB + THF + NaCl + 水系统的相平衡热力学建模


在本工作中，研究了添加热力学促进剂四正丁基溴化磷 （TBPB） 和四氢呋喃 （THF） 对 CO₂ 气体水合物形成条件的影响。考虑到海水用于形成大量水合物，研究了 NaCl 作为盐水中的主要盐在 THF 存在下对 CO₂ + TBPB 系统的相平衡的影响。此外，为了预测水合物形成的条件，van der Waals-Plateau 模型已被用于模拟水合物相平衡。SRK 状态方程已用于检查气相。e-NRTL 模型已用于估计活性系数，该系统的模型参数正在研究中。结果表明，在 （TBPB + THF） 水溶液中添加 NaCl（3% 质量分数）会改变 CO₂ 水合物形成的平衡条件。据观察，所提供模型预测的水合物压力与在 TBPB、THF 和 NaCl 存在下 CO₂ 水合物相平衡的现有实验数据非常吻合。模型参数也通过使用实验数据和优化方法进行估计。水合物解离压力的平均绝对偏差为 3.23%。