ABSORPTION OF SO2 INTO AQUEOUS-SOLUTIONS .2. GAS-LIQUID EQUILIBRIUM OF THE MGO-SO2-H2O SYSTEM AND GRAPHICAL PRESENTATION OF OPERATION LINESIN AN EQUILIBRIUM DIAGRAM

A procedure for calculating the relevant concentrations of sulfur diox ide in an MgO-SO2-H2O system and the construction of an equilibrium-op erational diagram showing the relation between c(tot) (the amount of t otal SO2 per unit mass of solution), c(com) (the total concentration o f Mg2+ in the solution expressed with SO32- and HSO3- using the corres ponding stoichiometric factors), Y (the excess of SO2 over amount nece ssary to form Mg(HSO3)(2) only, per unit mass of solution), pH, p(SO2) (the partial pressure of SO2), and the solubility of MgSO3 at differe nt temperatures in the range from 298 to 323 K is described. The proce dure uses the Rudzinski method for determining the pH of a complex aqu eous solution and Fitter's ion interaction model to calculate the acti vity coefficients in the mixture at various temperatures. The calculat ed concentrations match closely to those obtained by experiment. The d esign diagram at 323 K is used for graphical representation of the ope rating lines for absorption of SO2 taking place within an industrial S O2 absorption unit. Stage efficiency and SO2 removal of commercial Ven turi units was computed. The number of overall gas-phase mass transfer units for each stage was found to be in the range from 1 to 3.