Phase equilibrium modeling of structure H clathrate hydrates of methane + water "insoluble" hydrocarbon promoter using group contribution-support vector machine technique

In this work, the group contribution (GC) method is coupled with the least-squares support vector machine (LSSVM) mathematical algorithm to develop a model for representation/prediction of the dissociation conditions of structure H (sH) clathrate hydrates of methane with 21 hydrocarbon promoters namely as water "insoluble" promoters. Almost all of available literature data are studied to present a reliable model validated by the following statistical parameters: absolute average relative deviations (AARD) of the represented/predicted dissociation pressures from the reported experimental values: about 1.6%, and squared correlation coefficient: 0.99. © 2011 American Chemical Society.Ali Eslamimanesh, Farhad Gharagheizi, Amir H. Mohammadi, Dominique Richon, Mohammad Illbeigi, Alireza Fazlali, Amir Ahmad Forghani, and Mohammad Yazdizade

Chrastil-Type Approach for Representation of Glycol Loss in Gaseous System

International audienceGlycols are generally used to adjust the water dew-point in natural gas processes to avoid gas hydrate/ice/condensate formation. Their vaporization loss in gaseous systems may happen regularly in the petroleum industry. Glycols have very low solubility in the gas phase and because of difficulty of the corresponding measurement, few sets of experimental data are available in open literature and may not be fully satisfactory. In a previous work, we performed thermodynamic consistency tests in order to prepare reliable data sets for modeling purposes. Application of four widely used correlations in supercritical fluid industry, including the original Chrastil, Adachi and Lu, del Valle and Aguilera, and Mendez-Santiago and Teja, in which the effects of temperature, density of gas (solvent), and pressures on the solubility of glycol are generally taken into account, are investigated to represent the corresponding solubility of ethylene glycol and triethylene glycol in supercritical methane and carbon dioxide between 298.15 and 333.15 K and between 1.606 and 22.06 MPa. It is found that the absolute average deviations (AAD %) of the evaluated glycols solubility by the aforementioned equations from 57 investigated experimental values are around 27%, 18%, 31%, and 17%, respectively

Phase equilibrium measurements for semi-clathrate hydrates of the (CO 2 + N2 + tetra-n-butylammonium bromide) aqueous solution system : Part II

International audienceEquilibrium pressures for dissociation of the carbon dioxide (CO 2)+nitrogen (N 2)+tetra-n-butylammonium bromide (TBAB)+semi-clathrate (sc) hydrates have been experimentally measured to determine the stability regions and dissociation conditions of mixed CO 2+N 2+TBAB semi-clathrate hydrates. Semi-clathrates have been formed with the addition of TBAB aqueous solutions with mass fractions of (0.05 and 0.30). The relative molar fractions of CO 2 in the feed gas were (0.151, 0.399, and 0.749). Hydrate dissociation conditions have been measured using an isochoric pressure search method in the 275.1-291.0K temperature range and 0.67-19.07MPa pressure range. The obtained experimental clathrate hydrate dissociation data have been compared with the predictions of two thermodynamic models, namely CSMGem and HWHYD, available in open literature. Finally, the thermodynamic promotion effects of TBAB in aqueous solutions are discussed in terms of hydrate dissociation pressures and temperatures and consequently the most favorable operating conditions are proposed

Group Contribution-Based Method for Determination of Solubility Parameter of Nonelectrolyte Organic Compounds

Comment on "Group Contribution-Based Method for Determination of Solubility Parameter of Nonelectrolyte Organic Compounds" and "Solubility Parameters of Nonelectrolyte Organic Compounds: Determination Using Quantitative Structure-Property Relationship Strategy" Sierra Rayne, Industrial & Engineering Chemistry Research 2013 52 (10), 3947-3948; DOI: 10.1021/ie400117h Reply to "Comment on 'Group Contribution-Based Method for Determination of Solubility Parameter of Nonelectrolyte Organic Compounds' and 'Solubility Parameters of Nonelectrolyte Organic Compounds: Determination Using Quantitative Structure-Property Relationship Strategy"' Farhad Gharagheizi, Ali Eslamimanesh, Amir H. Mohammadi, and Dominique Richon, Industrial & Engineering Chemistry Research 2013 52 (10), 3949-3949; DOI: 10.1021/ie400202tInternational audienceThe determination of the solubility parameter of organic compounds has been of much significance in the chemical industry. In this study, we propose a predictive method based on the combination of the Group Contribution strategy with the Artificial Neural Network to calculate/estimate the solubility parameter values of about 1620 nonelectrolyte organic compounds at 298.15 K and atmospheric pressure. The chemical functional groups are obtained for various compounds categorized in 81 different chemical families. The final results indicate the following statistical parameters of the presented method: average relative deviation (ARD %) of the determined properties from existing experimental values of 1.5% and a squared correlation coefficient of 0.985. It is finally inferred that the developed model is more accurate and predictive than our previously proposed models based on the Quantitative Structure Property Relationship algorithm, which yielded 4.6, 3.4, and 3.1 ARD % from experimental values