High-Pressure Volumetric Properties of Carbon Disulfide, Carbonyl Sulfide, and Hydrogen Sulfide in Propane

Natural gas liquids can contain varying amounts of sulfur impurities that can impact thermophysical and thermochemical properties even after separation through liquefaction. Reference quality equations of state can be used to calculate property or composition changes, provided that reliable mixing parameters are available. Measuring accurate density and volumetric changes for select sulfur impurities associated with high-pressure propane liquids is one way to validate or reoptimize mixing parameters. In this work, the volumetric influence of three minor sulfur impurities (CS2, COS, or H2S) in dense propane was studied through high-precision density measurements at p < 35 MPa and T = 323397 K. The measured mixture and pure density data for CS2 + propane were used to calculate the apparent molar volumes, which were assumed to approximate the partial molar volume at infinite dilution. These partial molar volumes were then used to fit an infinite dilution correlation function based on the generalized Krichevskii parameter. The measured mixture densities for COS and H2S in propane were used to compare the estimated mixing coefficients of Kunz and Wagner (2012) along with reference quality equations of state. Density calculations performed with the mixing coefficients showed an agreement within +/- 0.4% at high pressures to our measured data and no reoptimization was necessary.