Chemical Engineering Research & Design, Vol.73, No.5, 512-518, 1995
Measurement of Drop Size Distribution in Concentrated Liquid-Liquid Dispersions - Video and Capillary Techniques
Distributions in a concentrated dispersion have been measured in a stirred vessel. With the capillary technique, with a wide distribution, even after extensive testing of different sized capillaries and entry conditions and of threshold levels, both ends of the distribution were cut off. Sampling time is a problem when studying fast transients, as is the amount of fluid withdrawn when investigating phase inversion. Provided pictures can be taken, the video technique allows droplets from 25 mu m upwards at concentrations up to those which cause phase inversion, i.e. similar to 70% by volume dispersed phase, to be observed. These observations can be made at the wall and, by means of a 7 mm diameter ’light pipe’ and similar sized optical fibre strobe, inside the vessel. With a framing rate of 50 per second, the technique gives, second-by-second, size distributions to any discretization and means to any base. The structure is also revealed; for example, droplets-in-drops and bubbles are distinguishable from drops.