A MODEL FOR CALCULATING VIRIAL-COEFFICIENTS OF NATURAL-GAS HYDROCARBONS WITH IMPURITIES

A model for calculating second and third virial coefficients, original ly developed to described the behavior of polar halocarbon refrigerant s and their mixtures, has been applied to systems of natural gas hydro carbons and their common impurities, namely H2S, H2O, CO2, CO, and N-2 . It can be used to correlate data, point out probable errors and prov ide predictions where data are nonexistent or unreliable. It also prov ides a means for calculating accurate gas-phase densities, thermodynam ic properties, fugacities, and ''calculated data'' which can be incorp orated into global equations of state for phase equilibrium calculatio ns. Examples are shown for some of the pure components and for the bin ary systems C2H6 + H2S and CH4 + H2O. In the case of H2O, terms are in cluded that account for association. Comparisons are made with availab le data, and predicted values are shown where no data exist.