The concentration of the HCl / H2O azeotrope varies with the pressure. The HCl / H2O azeotrope is slightly less concentrated at high pressure than at low pressure. It is therefore possible to overcome the azeotropic barrier by transferring HCl / H2O azeotropes at two different concentrations between two columns at different pressures.

(* Calculated using the Mixed Solvent Electrolyte model of OLI Systems, Incorporated)