Modelling Phase Equilibria in Systems with Organic Solid Solutions

Abstract

INTRODUCTIONThe formation of alloys of inorganic compounds has been known for centuries, yet it is not only on metallurgy and ceramics that metals and inorganic salts in general form mixed crystals. Reports on the formation of alloys, or solid solutions, of organic compounds, although still rare, have been appearing regularly in the last few years for aromatic compounds, such as substituted benzenes and naphtalenes [1][2][3], pyrene and anthracene [4][5][6], for carbohydrates [7], terpenes [8], neopentane derivatives [9-10] and fulerenes, besides solid solutions of C 60 with C 70 [11][12] solid solutions of C 60 in sulphur have been reported [13]. Nevertheless it is among the molecules with long n-alkyl chains such as n-alcohols Although the materials based on n-alkane alloys have been used for long as candles, waterproof coatings, pharmaceutical and cosmetics, and in spite of paraffin waxes being a valuable by-product of petroleum refining, the research on n-alkane solid solutions has been mainly prompted by its dark side: The damages and losses caused by wax precipitation from petroleum fluids. Every year wax deposition costs billions of dollars in preventive maintenance, remediation of pipeline blockages and losses of production [22,23]. Better computer models can help anticipate the problems allowing for preventive actions, optimization of actions and avoid losses by shutting down of production or by accident.The presentation of this chapter will focus on the prediction of the wax precipitation from petroleum fluids both at high pressures, in reservoir conditions, or at low pressures, as stock tank oil or fuels. In the final section the application of the model proposed to other systems of organic solid solutions will be discussed.

Solución de la ecuación de Rachford – Rice por homotopía diferencial

“…Con el fin de probar la robustez del método propuesto y abarcar diferentes configuraciones de distribución de fase, en esta investigación se incluyen diversos ejemplos del cálculos de equilibrio de tres fases con mezclas sintéticas que contienen hidrocarburos de tipo parafinados (sistema de hidrocarburos parafínicos de composición generada en función de los pesos moleculares de los componentes que van desde C1 hasta n-C28,) (17) o mezclas de los mismos con pseudocomponentes y agua (18) , además de una mezcla de etilenglicol, dodecanol y nitrometano (19) .…”

Activity Coefficient Models Part 2: Local Composition Models, from Wilson and NRTL to UNIQUAC and UNIFAC

“…The heat of sublimation can be obtained as the sum of the heats of vaporization, fusion and solid-solid transition of alkanes, all of which are given by correlations (see Coutinho 103 and Coutinho et al 108 ). The heat of sublimation can be obtained as the sum of the heats of vaporization, fusion and solid-solid transition of alkanes, all of which are given by correlations (see Coutinho 103 and Coutinho et al 108 ).…”

A New Thermodynamic Model for Paraffin Precipitation in Highly Asymmetric Systems at High Pressure Conditions

“…Jaubert and Mutelet combined their group contribution method with a cubic EoS to model VLE in highly asymmetric systems. They found that their group contribution scheme coupled with a cubic EoS gives better results compared to EoS/G E approaches of LCVM (which is widely used for describing fluid in solid–fluid equilibria of waxy systems in several example works ,− ) and MHV2 . The JMGC method for binary interaction parameters in modeling wax forming systems has been applied in some publications. , To be consistent, in this work, the fugacity of pure components in the liquid state are also calculated with the SRK EoS.…”