MASS-TRANSFER WITH CHEMICAL-REACTION AND PRECIPITATION

Precipitation involving three steps, namely gas-liquid mass transfer, chemical reaction and crystallization, is analysed in terms of the coupled equations for the film theory of gas-liquid mass transfer with chemical reaction and the mass and population balances of crystallization. The equations are solved numerically using literature data for the absorption of carbon dioxide gas into lime water. Non-uniform spatial distributions of supersaturation and nucleated particles due to the mass transfer resistance are reflected in the predicted crystal size distributions: larger particles are formed under conditions of high mass transfer into a large liquid volume (small specific surface area), while small particles of low variance are produced when the mass transfer coefficient is low.