Solids Classification

The conical discs in a disc bowl centrifuge split the liquid flow into a number of very thin layers, which greatly increases the separating efficiency. Disc bowl centrifuges are used for separating liquids and fine solids, and for solids classification. 

Hydrocyclones are used for solid-liquid separations as well as for solids classification, and liquid-liquid separation. It is a centrifugal device with a stationary wall, the centrifugal force being generated by the liquid motion. The operating principle is basically the same as that... 

A small imperfection corresponds to a sharp separation. Within the field of crystallisation the so-called classification function is used to define solids classification in terms of number population densities. 

For nonflocculant suspensions, gravity clarifiers are sometimes used as for solids classification. The theoretical grade efficiency curve G(x) of the clarifier can be predicted, assuming laminar flow and no end effects, by... 

When the principles of and equipment for the separation of solids from fluids are applied to solids classification, it is desirable to minimize the amount of misplaced material. This is related to the general slope of the grade efficiency curve which can be expressed in terms of a sharpness index defined in many different ways sometimes simply as the slope of the tangent to the curve atxso or, more often, as a ratio of two sizes corresponding to two different percentages on the grade efficiency curve on either side of 50%, i.e. for example ... 

FIGURE 3.33 Solids classification based on the width between conduction band CB and the valence band VB, at quantum level (left), with Si and C-diamond exemplification (right) after (Further Readings on Quantum Solid 1936-1967 HyperPhysics, 2003 Putz, 2006). 

Gas-solid Classification of the operations in this category according to the number of components which appear in the two phases is again convenient. 

In food processing, the major objectives are sometimes achieved at the expense of some loss of recognised nutrients. However, in other cases, important nutrients may become available only after appropriate processing, since inhibitors or other interfering compounds may be destroyed or inactivated. Toxic factors can sometimes be destroyed by denaturation, as with enzymes, protease inhibitors and phyto-haemagglutinins. They can also be physically removed, for example by leaching, solvent extraction or solid classification methods, as in the removal of gossypol from cottonseed protein, or of phytate from cereals. 

In this section we will compute the grade-efficiency curve and overall separation efficiency at low inlet solids (classification only) loadings (co < Cql)- The grade-efficiency curve for a given cyclone expresses the functional dependence of separation performance upon particle diameter. As discussed in Chap. 3, it is normally an s-shaped function satisfying the limits ... 

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