Scale-up techniques

Scale-up techniques for using the results of pilot plant or bench scale test w ork to establish the equivalent process results for a commercial or large scale plant mixing system design require careful specialized considerations and usually are best handled by the mixer manufacturer s specialist. The methods to accomplish scale-up will vary considerably, depending on whether the actual operation is one of blending, chemical reaction tvith product concentrations, gas dispersions, heat transfer, solids suspensions, or others. 

The choice of scale-up technique depends on the particular system. As a general guide, constant tip speed is used where suspended solids are involved, where heat is transferred to a coil or jacket, and for miscible liquids. Constant power per unit volume is used with immiscible liquids, emulsions, pastes and gas-liquid systems. Constant tip speed seems more appropriate in this case, and hence the rotor speed should be 0.66 Hz. The... 

Reprinted with permission from J. Y. Olclshue, Mixing Scale-Up Techniques Biotech. Bioeng. 8 (1966) 3—24. 1966 by John Wile Sons. Inc.. New York. NY. 

Oldshue, J. Y., "Current Trends in Mixer Scale-up Techniques," in Mixing of Liquids by Mechanical Agitation, ed. J. J. Ulbrecht and G. K. Patterson. New York Gordon and Breach Science Publishers, 1985, pp. 309-342. 

Oldshue, J.Y. "Fermentation Mixing Scale-up Techniques", Biotech, and Bioeng. VIII (1),3 (1966). 

Oldshue, J. Y., Fermentation Mixing Scale-Up Techniques, 5/otecA, Bioeng., VIII 3-24 (1966)... 

Reprinted with permission from J. Y. Olclshue, Mixing Scale-Up Techniques Biotech. 

Section three also contains a discussion of the use of genetically engineered microorganisms to produce agricultural chemicals. This area of research will certainly grow enormously in the future as scaled-up techniques of chemical production become cost-effective. 

Scale-up techniques used in heterogeneous catalysis are mainly outdated and ineffective. The knowledge base must be expanded, and a new workforce must be both educated and trained in the multiscale approach to build more fundamental, science-based models. 

An interesting scale-up technique exists for centrifuges. Essentially, it indirectly compares a given centrifuge to a settling tank that will perform the same function. This is done by using the cross-sectional surface area, of such a settling tank. The... 

Part A gives general guidelines for the design of large commercial fluidized bed reactors with respect to the following aspects (1) solids properties and their effect on the quality of fluidization (2) bubble size control through small solid particle size or baffles (3) particle recovery by means of cyclones (4) heat transfer tubes (5) solids circulation systems (6) instrumentation, corrosion and erosion, mathematical models, pilot plants and scale-up techniques. 

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