A general correlation of vapor-liquid equilibria in hydrocarbon mixtures is developed. The vaporization equilibrium ratio (K-value) is calculated through a combination of three factors

  • equation image

The quantity ν0 is a pure liquid component property and is correlated within the framework of Pitzer's modified form of the principle of corresponding states. The quantity γ is calculated from Hildebrand's equation, with regular liquid solutions assumed. The necessary parameters in this equation are specially determined for the very light components. The vapor state quantity ϕ is calculated from Redlich and Kwong's equation of state. The correlation is in the form of a compact set of equations which are especially suitable for application with an electronic digital computer.

The correlation applies to hydrocarbons of various molecular types, including paraffins, olefins, aromatics, and naphthenes. Hydrogen in hydrocarbon mixtures is likewise correlated. The correlation has been tested with a systematic compilation of literature data on mixtures of these components. The over-all average deviation from 2,696 data points is 8.7%.