Collect. Czech. Chem. Commun. 1979, 44, 2165-2172

Crystal size distribution of benzoic acid at its crystallization from the bulk of vapour phase

Jaroslav Vítovec, Jiří Smolík and Josef Kugler

Institute of Chemical Process Fundamentals, Czechoslovak Academy of Sciences, 165 02 Prague 6-Suchdol


Crystal size and their distribution were measured in the crystallizer with gas-permeable walls, at crystallization of benzoic acid vapours from the bulk of vapour phase in the mixture with nitrogen in dependence on concentration (in range from 1.1 to 23 vol.%), temperature (401 to 473 K) and velocity of mixture (0.5 to 6.6 cm/s). At small cooling rate of the mixture the vapours of benzoic acid are condensing in the form of droplets which at continuing cooling solidify. At cooling of the mixture by water dispersion create the needle-shaped crystals. The effect of concentration, temperature and velocity is not profound obviously because by evaporation of water is the mixture rapidly cooled and supersaturated. This results in creation of a large amount of crystal nuclei and thus also of small crystals.