Mixer effectiveness

Unlike centrifugal pumps and compressors, few criteria can be used directly to determine mixer effectiveness and efficiency. However, product quality and brake horsepower are indices that can be used to indirectly gauge performance. 

To obtain a measure of the overall mixer effectiveness, account needs to be taken of the number of times each volume element is visited by the tracer dividing by the total number of passes through all elements normalises these values. A measure of "mixer effectiveness" (ME) is then given by... 

CRITERIA OF MIXER EFFECTIVENESS MIXING INDEX. The performance of an industrial mixer is judged by the time required, the power load, and the properties of the product. Both the requirements of the mixing device and the properties desired in the mixed material vary widely from one problem to another. Sometimes a very high degree of uniformity is required sometimes a rapid mixing action sometimes a minimum amount of power. 

FIGURE 4.2 A reactor equipped with a mixer. Effects of different mixing rates and an illustration of stagnant zones due to inappropriate mixing. 

Charman M, Leonard E, Dominguez S, Bissuel C, Derail C (2011) Dispersion of multiwalled carbon nanotubes in a rubber matrix using an internal mixer effects on rheological and electrical properties. J Polym Sci B Polym Phys 49 1597-1604... 

Ainong the first TFIz mixers to be constructed were those based on room-temperature Schottky diodes [11]. Over the past decade, new mixers based on superconducting tunnel junctions have been developed that have effective noise levels only a few tunes the quantum limit of [12]. Flowever, certain conditions... 

However, such mixer—settler methods are continuous only by virtue of repeating a sequence of similar stages to achieve a given degree of extraction. More fully continuous methods of extraction were designed as tower systems and later as screw conveyor systems as effective methods of soHds transport became reHable. 

Fig. 4. Effect of impeller size on mixer pumping rate.

Correlations of nucleation rates with crystallizer variables have been developed for a variety of systems. Although the correlations are empirical, a mechanistic hypothesis regarding nucleation can be helpful in selecting operating variables for inclusion in the model. Two examples are (/) the effect of slurry circulation rate on nucleation has been used to develop a correlation for nucleation rate based on the tip speed of the impeller (16) and (2) the scaleup of nucleation kinetics for sodium chloride crystalliza tion provided an analysis of the role of mixing and mixer characteristics in contact nucleation (17). Pubhshed kinetic correlations have been reviewed through about 1979 (18). In a later section on population balances, simple power-law expressions are used to correlate nucleation rate data and describe the effect of nucleation on crystal size distribution. 

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