GENERATION OF OIL EMULSION FOR STIRRED-TANK PROCESSES

The presence of oil emulsion required in some processes occurring in stirred tanks, commonly used in various technologies, can be obtained either by high pressure injection of oil to the tank; or, by the impeller generating a higher shear rate in the tank, filled up with a carrier liquid to which the oil was poured. A simplified mathematical model for both methods has been derived, together with formulae to calculate the size of the oil droplet produced. The formulae show that the droplets get smaller with increasing oil density, carrier liquid density and viscosity, and with decreasing surface tension. The droplets diminish with increasing impeller diameter and speed, when a stirred tank is used, or diminish with atomized oil pressure. Theoretical results are compared to some measured data. The advantage of the injection method has been proven by experiments on a selective agglomeration of coal at a batch laboratory scale. In comparison to the impeller method, the injection method allowed the reduction of the total processing time by about 80%.