Abstract Polar soft-SAFT has been used in this work as a modeling tool to systematically assess the effect of impurities on the thermodynamic behavior of natural gas systems based on methane. The considered impurities include inert gasses (CO2, N2, CO), simple gasses (Ar, H2), sulfur-containing species (H2S, SO2, COS, methane- and ethane-thiols), and aromatic hydrocarbons (benzene, toluene, and xylenes). Polar soft-SAFT was first used to model the properties of pure compounds, including phase equilibria, speed of sound, Joule-Thomson effect, viscosity and interfacial tension. The predictive capability of the model for mixtures of the impurities with methane was assessed through comparison with available literature data, for different thermodynamic properties, obtaining excellent agreement in most of the cases, while an energy binary parameter was needed in few others. Additionally, the model's accuracy and robustness was further validated by accurately predicting the phase envelope of two multicomponent natural gas mixtures. The molecular models were subsequently used in a fully predictive manner to quantify the effect of the various impurities on density, speed of sound and viscosity of their binary mixtures with methane. It was established that the presence of hydrogen posed the largest decrease in density and viscosity of the gas, while increasing its speed of sound. Conversely, the presence of o-xylene resulted in the largest increase in both density and viscosity, while decreasing the speed of sound of the gas. These results demonstrate the effectiveness of soft-SAFT as a reliable tool for isolating and quantifying the effect of each individual impurity on the overall behavior of the systems, of clear implications for the industrial systems of interest.

中文翻译：

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使用 Polar soft-SAFT 评估杂质对基于甲烷的能源系统热物理特性的影响。

摘要 Polar soft-SAFT 已在这项工作中用作建模工具，以系统地评估杂质对基于甲烷的天然气系统热力学行为的影响。考虑的杂质包括惰性气体（CO2、N2、CO）、简单气体（Ar、H2）、含硫物质（H2S、SO2、COS、甲烷和乙烷硫醇）和芳烃（苯、甲苯和二甲苯）。Polar soft-SAFT 首先用于模拟纯化合物的性质，包括相平衡、声速、焦耳-汤姆逊效应、粘度和界面张力。通过与现有文献数据的比较，评估了模型对杂质与甲烷混合物的预测能力，对于不同的热力学性质，在大多数情况下获得了极好的一致性，而很少有其他人需要能量二进制参数。此外，通过准确预测两种多组分天然气混合物的相包络，进一步验证了模型的准确性和稳健性。随后以完全预测的方式使用分子模型来量化各种杂质对其与甲烷的二元混合物的密度、声速和粘度的影响。已经确定，氢气的存在导致气体密度和粘度的最大降低，同时增加了其声速。相反，邻二甲苯的存在导致密度和粘度的最大增加，同时降低了气体的声速。