For calculations involving hydrocarbon mixtures, various types of mixing rules are proposed. Where w is the acentric factor of the species, and R is the universal gas constant. The basic form of the Peng-Robinson cubic equation of state (as proposed in 1976) is given in Eq.1: The Peng-Robinson cubic equation of state was developed in 1976 at the University of Alberta by Deng-Yu Peng and Donald Robinson various variations of the Peng-Robinson cubic equation of state have been proposed since its inception. Generally, the Peng-Robinson cubic equation of state is preferred over the Soave-Redlich-Kwong cubic equation of state, as it can more accurately predict liquid phase properties. Of these, the Soave-Redlich-Kwong cubic equation of state and the Peng-Robinson cubic equation of state are the oldest and most widely used. Numerous cubic equations of state are given in literature. Since petroleum products are mixtures of predominantly non-polar and mildly polar hydrocarbons, cubic equations of state are widely used in predicting phase equilibrium properties in the oil and natural gas industries. Cubic equations of state give accurate results for non-polar and mildly polar hydrocarbons and their mixtures. These parameters are well-documented and readily available for most hydrocarbons. Also, cubic equations of state require few parameters, such as critical temperature, critical pressure and acentric factor, to calculate various phase equilibrium properties. The cubic equations of state-based models are preferred over other models, as these models require the same set of equations to be solved for both liquid and vapor phase. TheoryĪccurate prediction of phase equilibrium properties requires solving models using complex equations.
WATER PHYSICAL PROPERTIES CALCULATOR SOFTWARE
The proprietary VLE software is designed to give accurate phase equilibrium properties for any mixture of nonpolar or mildly polar hydrocarbons and inorganic gases up to a maximum number of 112 components in the hydrocarbon mixture. The Peng-Robinson cubic equation of state and Van der Waals mixing rule using a combination of temperature-dependent and constant binary interaction parameters are used for these calculations. Simulation of these atmospheres also requires knowledge of phase equilibrium properties.Ī new vapor liquid equilibrium (VLE) software a has been developed using basic calculation tools like MS Excel and Visual Basic for Applications (VBA, macro programming) to accurately calculate various phase equilibrium properties. Atmospheres of various heavenly bodies are made of hydrocarbons, such as methane (CH 4), ethane (C 2H 6), propane (C 3H 8), etc., and inorganic gases like nitrogen (N), carbon dioxide (CO 2) and hydrogen sulfide (H 2S). Phase equilibrium properties are also required in upstream oil and gas activities like well simulation and oil and natural gas production. These phase equilibrium properties find usage in the design and operation of all kinds of hydrocarbon equipment, such as hydrocarbon pipelines, hydrocarbon pumps, pressure vessels, hydrocarbon storages and distillation columns. Phase equilibrium properties, such as bubble-point, hydrocarbon dewpoint, water dewpoint, phase envelope, two-phase compositions, compressibility factor, hydrate equilibrium properties, etc., for hydrocarbon mixtures have been calculated accurately using the Peng-Robinson cubic equation of state by implementing constant and temperature-dependent binary interaction parameters in the Van der Waals mixing rule.