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Abstract
Mixing is one of the common unit operation employed in chemical industries. Conventional mixers are equipped with impellers but are expensive for mixing in large storage tanks and underground tanks. Jet mixers have become an alternative to impellers for over 50 years in the process industry. For the design of jet mixers, the detailed hydrodynamics of the mixing process is not properly understood. In the present paper, hydrodynamic techniques are used to simulate jet mixing in a cylindrical tank. The flow circulation patterns with in the tank and their effect on mixing of a soluble salt are studied. An experiment was carried out to study the effects of various parameters such as nozzle diameter, jet position and jet velocity on mixing time. Results show that, for a given geometric arrangement, jet dia is significantly more important in determining mixing time of jet mixer for Newtonian fluids. The optimum jet was found to be the jet dia of 15 mm for jet located at various positions at the top of the tank which gave the shortest mixing time for Newtonian fluids. An increase in the nozzle diameter was found to reduce the mixing time at a given level of power consumption and in turn in the energy efficiency can be improved. The results obtained shows a good understanding of hydrodynamic aspects of mixing process in jet mixed tanks.