Mixing in Stirred Tanks

The existence of solid particles suspended in the hquid caused an increase in the hquid mixing time. In contrast, aeration caused a decrease in the hquid mixing time for water, but an increase for non-Newtonian hquids [14]. 

A stirred-tank reactor equipped with a standard Rushton turbine of the following dimensions contains a hquid with density p = 1.0 g cm and viscosity 

---

Liquid mixing in stirred tanks is covered in Volume 1, Chapter 7, and in several textbooks Uhl and Gray (1967), Hamby et al. (1997) and Tatterson (1991), (1993). 

The objectives of liquid mixing in stirred tanks are to (i) make the liquid concentration as uniform as possible (ii) suspend the particles or cells in the liquid (iii) disperse the liquid droplets in another immiscible liquid, as in the case of a liquid-liquid extractor (iv) disperse gas as bubbles in a liquid in the case of aerated (gassed) stirred tanks and (v) transfer heat from or to a liquid in the tank, through the tank wall, or to the wall of coiled tube installed in the tank. 

Holland, F. A. and Chapman, F. S. (1966a) Liquid Processing and Mixing in Stirred Tanks (Reihhold). Holland, F. A. and Chapman, F. S. (1966b) Pumping of Liquids (Reinhold). 

Thoma, S. Interactions Between Macro- and Micro-Mixing in Stirred Tank Reactors. Dissertation No. 9012, ETH, Zurich, 1989. 

Harvey III A.D., West D.H., Tufiliaro N.B., Evaluation of laminar mixing in stirred tanks using a discrete-... 

The Taylor micro scales of turbulence can be calculated from the same functions /(t, x) and g t,x) using (1.317) and (1.319), respectively. However, the resulting scales do not characterize any distinct group of turbulence vortices and are thus not very useful in describing micro mixing in stirred tanks. 

The major part of the book deals with nonideal reaetors. Chapter 4 on pore diffusion plus reaetion ineludes a new method for analyzing laboratory data and has a more eomplete treatment of the effeets of eomplex kineties, particle shape, and pore structure than most other texts. Catalyst design to minimize pore diffusion effects is emphasized. In Chapter 5 heat transfer correlations for tanks, particles, and packed beds, are reviewed, and the conditions required for reactor stability are discussed. Examples of unstable systems are included. The effects of imperfect mixing in stirred tanks and partial mixing in pipeline reactors are discussed in Chapter 6 with examples from the literature. Recommendations for scaleup or scaledown are presented. 

Kramers H, Baars GM, Knoll WH. (1953) A comparative study on the rate of mixing in stirred tanks. Chem. Eng. Sci., 2 35 2. 

Laminar Mixing in Stirred-Tank Reactor Numerical Study... 

Yakoob Z., Kamruddin S.K., Hasran U.A. Experimental and numerical studies of laminar mixing in stirred tanks. CIMMA CS 08 Proceedings of the 7th WSEAS International Conference on Computational Intelligence, Man-Machine Systems and Cybernetics, 2008 978(474) 149-151. 

Imperfect macro-mixing in stirred tank reactors with turbulent flow can have three different effects ... 

A new micromixing (shrinking aggregate)model has been proposed, which describes the first stages of mixing in stirred tanks. 

Baldyga, J., J. R. Bourne, and Y. Yang (1993). Influence of feed pipe diameter on meso-mixing in stirred tank reactors, Chem. Eng. ScL, 48, 3383-3390. 

Bourne, J. R., and P. Dell Ava (1987). Micro- and macro-mixing in stirred tank reactors of different sizes, Chem. Eng. Res. Des., 65, 180-186. 

Thoma, S. (1989). Interactions between macro- and micro-mixing in stirred tank reactors. 

---