ABSTRACT
Mixing operation in which the rheological properties of the medium change over the course of the mixing process are common in the chemical industries [1]. A standard stirred tank which equipped with the impeller is commonly used as mixing system. Also, the baffles are mounted on the tank wall to avoid circulatory motion of the fluid and to destroy surface vortices. Viscosity is one of the most important rheological properties that have great significance in the process [2]. For low viscosity non-Newtonian fluids, the high speed blade turbines such flat blade turbines, pitched blade turbines and hydrofoils etc. are commonly used for mixing system. The selection of good impeller is depended on the mixing duty requirement like the operating speed, discharge characteristics and the power draw. But for high viscosity fluids mixing, the close clearance impellers like helical ribbon impeller are preferred [3]. Hence, the mixing tank performance is depending on an appropriate adjustment of the reactor hardware and operating parameters like reactor and impeller shapes, aspect ratio of the reactor vessel, degree of baffling, etc., which provide effective means to control the performance of stirred reactors [4].
