Application of the Cubic-Plus-Association (CPA) Equation of State to Complex Mixtures with Aromatic Hydrocarbons

Folas, Georgios K.; Kontogeorgis, Georgios M.; Michelsen, Michael Locht; Stenby, Erling Halfdan

doi:10.1021/ie050976q

Cited by 111 publications

(126 citation statements)

References 45 publications

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“…Although the aromatic hydrocarbons are themselves non-self-associating, it is well known that aromatic compounds are able to cross associate (solvate) with water [37,38,63]. A solvation scheme involving combining rules for the cross-associating energy and volume parameters [30] was here employed. Using this approach both the binary interaction parameter k ij and the cross-association volume β A i B j are fitted to experimental equilibrium data.…”

Section: Resultsmentioning

confidence: 99%

“…When CPA is employed to mixtures containing crossassociating molecules, which is the case of the systems with aromatic hydrocarbons and H 2 O studied in this work, combining rules for the association energy and volume parameters are required [30,36]. For these systems the approach suggested by Folas et al [30] was adopted.…”

Section: Modelmentioning

confidence: 99%

“…For these systems the approach suggested by Folas et al [30] was adopted. The cross-association energy between aromatic hydrocarbons and water is taken as half the water association energy and the cross association volume (β A i B j ) is used as an adjustable parameter fitted to equilibrium data:…”

Section: Modelmentioning

confidence: 99%

“…Nevertheless the results obtained until present seem to indicate that within the association equations of state the CPA EoS is the most successful association model for the description of water containing systems, with alkanes, alkenes, cycloalkanes [29], aromatics [30], alcohols [31] glycols [32] and perfluorocarbons [33].…”

Section: Introductionmentioning

confidence: 97%

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Mutual solubilities of hydrocarbons and water with the CPA EoS

Oliveira

Coutinho

Queimada

2007

Fluid Phase Equilibria

145

103

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The knowledge of hydrocarbon/water phase equilibria is important in the design and operation of equipment for petroleum transport and refining and petrochemical plants. The presence of water in a hydrocarbon mixture can affect the product quality and damage the operation equipment due to corrosion and formation of gas hydrates. Tracing the concentration of hydrocarbons in aqueous media is also important for technical purposes like preventing oil spills and for ecological concerns such as predicting the fate of these organic pollutants in the environment.In spite of its huge interest there was no model able for a qualitative description of the mutual solubility of water and hydrocarbons for a broad range of systems in a wide range of thermodynamic conditions. In this work it is shown that an equation of state incorporating association known as the CPA EoS is able to produce an excellent description of the mutual solubilities of water and several aliphatic and aromatic hydrocarbons in a broad range of pressures and temperatures.

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Section: Resultsmentioning

confidence: 99%

Section: Modelmentioning

confidence: 99%

Section: Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

See 2 more Smart Citations

Mutual solubilities of hydrocarbons and water with the CPA EoS

Oliveira

Coutinho

Queimada

2007

Fluid Phase Equilibria

145

103

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“…non self-associating) compound where there is possibility for solvation between the two compounds. For this purpose, specially suited is the socalled modified CR-1 rule proposed by Folas et al (2006a), which has been applied to mixtures with water or glycols and aromatic or olefinic hydrocarbons. In the modified CR-1 combining rule, we select the energy to be half the value of the energy for the self-associating component, whereas the cross-association volume is teaken as an adjustable parameter regressed from experimental data:…”

Section: The Cpa Equation Of Statementioning

confidence: 99%

Solvation Phenomena in Association Theories with Applications to Oil & Gas and Chemical Industries

Kontogeorgis

Folas

Muro-Suñé

et al. 2008

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Les théories d'association et le phénomène de la solvatation : application aux industries du pétrole et du gaz, et à la pétrochimie -Les théories de l'association issues de la famille des équations SAFT (Self Associating Fluid Theory) expriment explicitement le phénomène de l'autoassociation ainsi que de l'association croisée. Ces phénomènes ont une grande importance pratique car ils ont un effet souvent majeur sur l'équilibre de phases de nombreux mélanges d'intérêt industriel. D'un point de vue scientifique, le phénomène de la solvatation est également beaucoup étudié car il intervient dans de nombreux types de mélange, et non seulement ceux contenant des composants auto-associés comme les mélanges de l'eau avec les alcools ou les glycols. Des mélanges ne contenant qu'un seul composé auto-associé, voire aucun, peuvent néanmoins présenter une solvatation spécifique liée à la formation de liaisons hydrogène ou, de manière plus générale, à des interactions de type acide -base de Lewis. Comme exemple, on peut mentionner les mélanges avec un composé polaire (eau, glycol...) et des hydrocarbures aromatiques ou des solutions aqueuses d'éthers ou d'esters. Ce manuscrit décrit comment le modèle dit "CPA" (Cubic Plus Association), qui contient un terme spécifique pour l'association, issu de l'équation SAFT, peut être utilisé pour rendre compte de différents types d'interactions de solvatation. Le rôle des règles de combinaison dans le terme associatif et les cas où la solvatation doit être traitée explicitement sont illustrés. Abstract -Solvation Phenomena in Association Theories with Applications to Oil & Gas and

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Applications of CPA to the Oil and Gas Industry

Kontogeorgis

Folas

2009

Thermodynamic Models for Industrial Applications

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There are various applications in the oil and gas industry where associating and/or oligomeric compounds are present. For these applications, it is expected that association models may be the preferred approach. Some examples are gas hydrate inhibitors, e.g. methanol and glycols, other flow assurance problems, e.g. related to asphaltenes, the variety of drilling, production and injection chemicals used in the oil industry, for which their environmental fate must be assessed and their use must be optimized, and finally the use of ethanol and other oxygenated polar compounds as additives in gasoline. Some of these examples are discussed below in more detail.Methanol is possibly the most important gas hydrate inhibitor. It suppresses gas hydrates but is often injected at a higher rate than necessary, due to uncertainties as to what the correct rate should be. Two important reasons for optimizing the amount of methanol used for inhibition (and keeping it to a minimum) are the cost of providing this chemical, especially on offshore platforms, and the fact that methanol is a toxic substance. The injection rate is directly related to the phase equilibria of mixtures containing oil, water and methanol. Moreover, the loss of hydrate inhibitor in the gas or condensate phases should be accurately known.Typically methanol is not being regenerated because it is relatively inexpensive. Common alternatives to methanol are the glycols, especially monoethylene glycol (MEG), which is added at rates up to 100% of the weight of water. Due to the high cost of MEG, regeneration is required, which, however, adds to the capital and operational cost as well as space requirements, especially for offshore installations. Hence, optimization of the MEG injection rate and minimizing the amount of MEG lost (mainly) in the hydrocarbon liquid and aqueous phases are directly related to the elimination of operational problems and decrease of cost.Another important problem where associating compounds are involved in the petroleum industry is related to the production and processing of natural gas. As previously discussed, the freezing diagrams of MEG-water and methanol-water have two eutectic points and an intermediate phase which indicates the formation of a solid (complex) hydrate between the two compounds. When natural gas is being produced from offshore fields, e.g. in the North Sea, and then transported to the gas plant, it is brought to sales gas specifications by a series of separators. In order to prevent the formation of gas hydrates during transportation and further processing, inhibitors such as ethylene glycol (MEG) are continuously added to the produced mixture (water and light hydrocarbons). Decreased efficiency has been observed in the separators at MEG concentrations, where according to the literature problem-free operation would be expected. This means that the concentration of ethylene glycol is high enough to inhibit formation of gas hydrates and low enough to prevent freezing of ethylene glycol. Experimental investigations indic...

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Application of the Cubic-Plus-Association (CPA) Equation of State to Complex Mixtures with Aromatic Hydrocarbons

Cited by 111 publications

References 45 publications

Mutual solubilities of hydrocarbons and water with the CPA EoS

Mutual solubilities of hydrocarbons and water with the CPA EoS

Solvation Phenomena in Association Theories with Applications to Oil & Gas and Chemical Industries

Applications of CPA to the Oil and Gas Industry

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