Densities of mixtures of carbon dioxide and hydrogen sulfide from 200 to 450 K to 23 MPA by the Burnett-isochoric method

Abstract

A combined Burnett-isochoric apparatus was designed and constructed to measure the pressure, density and temperature (P[rho]T) properties of corrosive fluids between 200 and 450 K to pressures of 21 MPa. Automated temperature control and compact design allow for rapid measurements of corrosive and reactive fluids. Innovative design of the isochoric cell and differential pressure transducer have improved construction and assembly. An integrated circuit is used to detect the position of differential pressure transducer which reduces the electronics costs by an order of magnitude and provides a direct input into the control program. The performance of the apparatus was verified through measurements of pure carbon dioxide and helium. Pressure, density and pressure (P[rho]T) properties and phase boundaries of two carbon dioxide and hydrogen sulfide gas mixtures: (CO2(1) + H2S(2), x1 = 0.94, 0.50, were measured between 200 and 450 K and to pressures of 23 MPa. Densities were determined to an accuracy from [plus or minus]0.1% to [plus or minus]0.4%. Phase boundaries were determined to [plus or minus]0.05 K and [plus or minus]0.001 MPa. The Tsonopoulos correlation predicted accurately the derived second virial coefficients for the mixtures using a binary interaction parameter, k[y] = 0.08. A similar correlation of Obrey and Vera predicted the derived third virial coefficients. These correlations were used to calculate virial coefficients of the mixtures to 250 K. Energies and entropies (U, H, A, G, S) were calculated throughout the temperature and pressure range.