Prediction of fluid density at extreme conditions using the perturbed-chain SAFT equation correlated to high temperature, high pressure density data

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• 作者：Ward A. Burgess^a ; ^{Ward.Burgess@or.netl.doe.gov} ; Deepak Tapriyal^a ; ^b ; Bryan D. Morreale^a ; Yue Wu^a ; ^c ; Mark A. McHugh^a ; ^c ; Hseen Baled^a ; ^d ; Robert M. Enick^a ; ^d
• 关键词：PC-SAFT ; High temperature ; High pressure ; Density ; Hydrocarbon
• 刊名：Fluid Phase Equilibria
• 出版年：2012
• 期刊代码：32_03783812
• 类别：ce
• 出版时间：14 April, 2012
• 卷：319
• 期：Complete
• 页码：55-66
• 文件大小：2141 K

摘要

At pressures below 鈭?5 MPa, the perturbed chain - statistically associated fluid theory (PC-SAFT) gives reliable density predictions within 卤2%for n-alkanes and other hydrocarbons. However, PC-SAFT tends to over-predict density values by as much as 5%at higher pressures, particularly for normal and branched alkanes. For many compounds, literature values for the three pure-component PC-SAFT parameters m, 蟽, and 蓻/k_B are typically obtained by fitting the equation to sub-critical P蟻T data or occasionally both sub-critical and supercritical density data. A new set of pure-component PC-SAFT parameters for density prediction at extreme conditions is reported here by fitting the PC-SAFT equation to single-component density data collected at temperatures from ambient to 533 K and pressures from 鈭?.9 to 276 MPa, rather than sub-critical density data since these high temperature, high pressure (HTHP) conditions are similar to conditions typically associated with petroleum recovery from ultra-deep formations. Density predictions made using the new, HTHP PC-SAFT pure-component parameters at HTHP conditions are clearly superior to those obtained using the original PC-SAFT parameters. Although a correction term can be applied to the 蓻/k_B parameter to make HTHP PC-SAFT pure-component density predictions at pressures below 6.9 MPa only slightly inferior to predictions with the original PC-SAFT parameters, vapor-liquid equilibrium predictions with the original PC-SAFT parameters are clearly superior to predictions made with the HTHP parameters. Correlations are developed to accurately predict the HTHP PC-SAFT parameters for normal and branched alkanes for which there are either incomplete or nonexistent experimental density data sets.