Phase equilibria and volumetric properties of the systems KCl-H2O and NaCl-KCl-H2O above 573 K: Equation of state representation

A comprehensive equation of state has been developed for the system KC1-H2O at high temperatures and pressures. The equation is based on a theoretical model developed earlier for the system NaCl-H2O. Experimental vapor-liquid equilibrium, solid-liquid equilibrium, and density data have been critically evaluated and used to fit the adjustable parameters of the model. The equation of state reproduces these properties within experimental uncertainty. It is valid for temperatures between 573 K and 973 K and pressures up to 5 kbar. Graphs are presented to provide recommended values of phase compositions and volumetric properties. Furthermore, the equations for NaCl-H2O and KC1-H2O have been combined to yield an equation for the ternary system NaCl-KCl-H2O. The equation reproduces solid-liquid equilibrium data for the ternary system and agrees with the available semiquantitative information about the relative concentration of Na and K in the vapor phase.