Mechanism solids mixing

Figure 24 Solids mixing mechanism in fluidized beds wake and drift.

Solids. For mixing of soflds the mixers can be categorized according to the mixing mechanism used. 

Kneading Devices These are closely related to the agitated pan but differ as being primarily mixing devices with heat transfer a secondary consideration. Heat transfer is provided by jacketed construction of the main body and is effected by a coolant, hot water, or steam. These devices are applicable for the compounding of divided solids by mechanical rather than chemical action. Apphcation is largely in the pharmaceutical and food-processing industries. For a more complete description, illustrations, performance, and power requirements, refer to Sec. 19. 

Mixing Mechanisms There are several basic mechanisms by which solid particles are mixed. These include small-scale random motion (diffusion), large-scale random motion (convec tion), and shear. 

Solid mixed ionic-electronic conductors (MIECs) exhibit both ionic and electronic (electron-hole) conductivity. Naturally, in any material there are in principle nonzero electronic and ionic conductivities (a i, a,). It is customary to limit the use of the term MIEC to those materials in which a, and 0, 1 do not differ by more than two orders of magnitude. It is also customary to use the term MIEC if a, and Ogi are not too low (o, a i 10 S/cm). Obviously, there are no strict rules. There are processes where the minority carriers play an important role despite the fact that 0,70 1 exceeds those limits and a, aj,i< 10 S/cm. In MIECs, ion transport normally occurs via interstitial sites or by hopping into a vacant site or a more complex combination based on interstitial and vacant sites, and electronic (electron/hole) conductivity occurs via delocalized states in the conduction/valence band or via localized states by a thermally assisted hopping mechanism. With respect to their properties, MIECs have found wide applications in solid oxide fuel cells, batteries, smart windows, selective membranes, sensors, catalysis, and so on. 

Litka, T., and Glicksman, L. R., The Influence of Particle Mechanical Properties on Bubble Characteristics and Solid Mixing in Fluidized Beds, Powder Technol., 42 231 (1985)... 

PdxZS catalysts. Appropriate amounts of HZSM-5 or NaZSM-5 and Pd(acac)2 are mixed mechanically for 15 min in a mortar. The resulting solid is then treated in flowing helium or flowing oxygen (25 ml/min) at 2°C/min to 500°C and kept at this... 

In practical applications, dispersion calculations need to be performed in topographically complex environment. Thus, solid obstacles intervening in the area dispersion should be counting in the computations. In previous validation works, it has been proved that CFD codes constitute powerful tools for complex terrain dispersion simulation providing high accuracy results with excellent visualization capabilities, which can be helpful in quantitative risk analysis applications [55]. The dominating mixing mechanism between... 

Rowe, P.N., Partridge, B.A., Cheney, A.G., Henwood, G.A. and Lyall, E., The mechanisms of solids mixing in fluidised beds, Trans. Inst. Chem. Engrs., 43 (1965) 271-286. 

During recent years, however, the distinction between these two types of methods has become less clear because of the improved methods of sample cleanup that allow selective isolation of groups of compounds. Mixed-mechanism solid-phase extraction procedures and multi-immunoaffinity techniques are clear examples of liquid chromatographic developments that have contributed greatly to the current state of the art within residue analysis. 

There are no standard engineering classification methods for mixing equipment, and often, quite different types of mixers can fulfill the same mixing task. Nevertheless, we can subdivide mixers used in processing into three broad categories particulate solids mixers, laminar distributive mixers, and laminar dispersive mixers. This classification, on the basis of application, is supported by the nature of the primary mixing mechanism taking place in them. 

Solid-solid mixing is different from other multi-phase mixing with respect to the fact that the liquid phase does not participate in it. Solid-solid mixing is promoted when the outer force exceeds the gravity and the surface force. The mechanism consists of three factors ... 

What follows is a survey of the fluid-mechanical principles of fluidization technology, gas and solid mixing, gas-solid contact in the fluidized bed, typical industrial applications, and approaches to modeling fluidized-bed reactors. Further information is given in... 

It has also been found that it is not necessary to pack the oxidant into a column. The alkene, dissolved in dichloromethane, can be cleaved by ding it to a flask containing KMn04 and silica gel that have been mixed mechanically. After shaking or stirring the mixture for an appropriate time, the product can be isolated by filtration and evaporation of the solvent. Alumina can also be used equally well as the solid support.Additional examples are summarized in Table 11. 

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