Expanded Laser Beam for Online Measurement of Dispersed Phase Holdup in Agitated Flow Liquid-Liquid Mixer of Pilot Plant Scale

Laser transmission Technique (LTT) where a laser beam is used in conjunction with a beam, that is expanded enough to cover the average droplet size of the dispersed liquid in a liquid-liquid mixture has been applied for continuous measurement of the droplet phase volume fraction in agitated flow mixer of a pilot plant scale. The nature of difficulties inherent with the online measurement of the droplet phase holdup in an environment free of hydrodynamic disturbance when a wave of light is transmitted through the dispersion path of the liquid mixture are discussed. This study reports the first data for continuous measurements of dispersed phase holdup for a pilot plant scale liquid-liquid mixer of commercial design, where the measurements have no limitations to the geometrical aspects. Experimental results from a cubic mixing tank with dispersion depth of 30 cm were recorded. Online measurements were carried out in the presence of revolving impeller and transmission of a laser beam. The volume of the liquid-liquid mixer was 20.42 liter and the successfully measured dispersed phase holdup was ranged between 0.15-0.75. In this work, the arrangement of the laser setup was made to scan and measure the average liquid-liquid mixer holdup in the pilot plant scale of flow agitated liquid-liquid mixer. Thus, the LTT measurements was validated by comparing its results with that obtained from the liquid-liquid mixer shut-down procedure. In addition, the variation of the local holdup of the dispersed phase measured by LTT along the liquid-liquid mixer height has been studied and will be discussed.