Abstract One of the major problems in flow assurance, especially in the case of deep subsea pipelines, is the accumulation of gas hydrates that leads to significant issues such as pipe plugging and cracking. Utilization of thermodynamic inhibitors is an effective method to prevent hydrate formation in pipelines. Recently, ionic liquids (ILs) have been recognized as new hydrate inhibitors due to their strong electrostatic charges, which form hydrogen bonds with water molecules. In this work, the capability of the PC-SAFT/UNIQUAC model combined with the van der Waals-Platteeuw theory is assessed for estimation of the methane hydrate dissociation temperatures in the presence of various IL solutions. Five pure-component parameters of PC-SAFT EOS for ILs are fitted by using experimental data of liquid density. Furthermore, vapour-liquid and hydrate equilibria experimental data are employed to adjust the binary interaction parameters of the PC-SAFT EOS ( k ij ) and the UNIQUAC model ( u ij ), respectively. Methane hydrate dissociation temperatures are successfully forecasted by using the proposed model for ten (10) IL systems with different concentrations in which the overall average absolute deviation for temperature (AADT %) of the model is lower than 1.5%. The results clearly demonstrate that the developed thermodynamic model is capable of precisely obtaining the methane hydrate dissociation temperatures in the presence of IL solutions, though, for [EMIM][Cl] solutions with a concentration of more than 30 wt%, the model overestimates the methane hydrate conditions. The proposed thermodynamic modeling strategy can assist to screen suitable IL solutions with an optimal composition for hydrate formation inhibition in terms of technical, economic, and environmental prospectives.

中文翻译：

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PC-SAFT/UNIQUAC 模型评估在咪唑基离子液体体系存在下甲烷水合物的形成条件

摘要 流动保障的主要问题之一，特别是在深海管道的情况下，是天然气水合物的积累，导致管道堵塞和开裂等重大问题。使用热力学抑制剂是防止管道中形成水合物的有效方法。最近，离子液体（ILs）由于其强静电荷而被认为是新的水合物抑制剂，其与水分子形成氢键。在这项工作中，评估了 PC-SAFT/UNIQUAC 模型与范德瓦尔斯-普拉特理论相结合的能力，用于估计存在各种 IL 溶液时的甲烷水合物离解温度。利用液体密度的实验数据拟合了用于ILs的PC-SAFT EOS的五个纯组分参数。此外，气液平衡和水合物平衡实验数据分别用于调整PC-SAFT EOS ( k ij ) 和UNIQUAC 模型( u ij ) 的二元相互作用参数。通过使用针对具有不同浓度的十 (10) 个 IL 系统的建议模型成功地预测了甲烷水合物的解离温度，其中模型的总体平均温度绝对偏​​差 (AADT %) 低于 1.5%。结果清楚地表明，开发的热力学模型能够精确地获得 IL 溶液存在下甲烷水合物的解离温度，但是，对于浓度超过 30 wt% 的 [EMIM][Cl] 溶液，该模型高估了甲烷水合物条件。