Intermediate size reduction

Multiple-stage coolers with intermediate size reduction. . . 355... 

The example relates to a three-stage cooler, with intermediate size reduction, of the type built by the engineering firm of Claudius Peters. The principles it embodies are essentially applicable to ail other reciprocating grate coolers, including for... 

A multiple-stage cooler with intermediate size reduction of the clinker is a complicated installation and economically justified only in connection with a heat-economizing kiln fed with meal and attaining a clinker output exceeding about 2000t/day. 

Fig.27 Combination cooler with intermediate size reduction heat balance...

In the three-stage cooler with intermediate size reduction under consideration there is a vertical front end wall. In order to prevent having locally too thin a bed of clinker, the first row of plates is stationary and the plates have no holes. The clinker that remains lying on these plates protects them and prevents the formation of localized air escape passages. Similar considerations apply to the edge plates of the first two rows not covered with monolithic refractory fill, which likewise have plates without holes. This is known as the "horseshoe" arrangement of plates. An example of this system in actual practice is shown in Fig. 22. 

In the example of the three-stage cooler with intermediate size reduction, the last row of plates in grate 1 and the first row in grate 2 are stationary rows. In this way a banking-up effect is obtained, so that the clinker does not rush too quickly onto the... 

Since it is good practice to maintain a selected inventory of spare parts for drives, economy can be achieved by standardizing conveyor drives throughout the plant. For example, intermediate speed reduction by means of V belts, sheaves or chains, and sprockets can frequently permit using the same speed-reducer size for several drives. Thus, it may be necessary to keep only one repair-stock speed reducer for a number of conveyors. 

In practice, the process regime will often be less transparent than suggested by Table 1.4. As an example, a process may neither be diffusion nor reaction-rate limited, rather some intermediate regime may prevail. In addition, solid heat transfer, entrance flow or axial dispersion effects, which were neglected in the present study, may be superposed. In the analysis presented here only the leading-order effects were taken into account. As a result, the dependence of the characteristic quantities listed in Table 1.5 on the channel diameter will be more complex. For a detailed study of such more complex scenarios, computational fluid dynamics, to be discussed in Section 2.3, offers powerful tools and methods. However, the present analysis serves the purpose to differentiate the potential inherent in decreasing the characteristic dimensions of process equipment and to identify some cornerstones to be considered when attempting process intensification via size reduction. 

Multiple receive systems with multi-coil arrays have become widely distributed in medical MRI. The benefit is the enhancement of the signal-to-noise ratio per time or a reduction of the acquisition time. This technique is not used in NMR microscopy for objects of intermediate size in standard bore (52-mm id) and wide bore (89-mm id) magnets, which are the most widely distributed magnet types for NMR microscopy. The main reason is the restricted space in such magnets for the shim... 

In a chemical process, the transformation of raw materials into desired chemical products usually cannot be achieved in a single step. Instead, the overall transformation is broken down into a number of steps that provide intermediate transformations. These are carried out through reaction, separation, mixing, heating, cooling, pressure change, particle size reduction or enlargement. Once individual steps have been selected, they must be interconnected to carry out the... 

Whilst the mechanism of the process of size reduction is extremely complex, in recent years a number of attempts have been made at a more detailed analysis of the problem. If a single lump of material is subjected to a sudden impact, it will generally break so as to yield a few relatively large particles and a number of fine particles, with relatively few particles of intermediate size. If the energy in the blow is increased, the larger particles will be of a rather smaller size and more numerous and, whereas the number of fine particles will be appreciably increased, their size will not be much altered. It therefore appears that the size of the fine particles is closely connected with the internal structure of the material, and the size of the larger particles is more closely connected with the process by which the size reduction is effected. 

The cell-kill hypothesis states that the effects of antitumor drugs on tumor cell populations follow first-order kinetics. This means that the number of cells killed is proportional to the dose. Thus, chemotherapy follows an exponential or log-kill model in which a constant proportion, not a constant number, of cancer cells are killed. Ilieoretically. the fractional reductions possible with cancer chemotherapy can never reduce tumor populations to zero. Complete er ica-tion requires another effect, such as the immune response. A modified form of the first-order log-kill hypothesis holds that tumor regressions produced by chemotherapy are de-.scribed by the relative growth fraction present in the tumor at the lime of treatment This idea is consistent with the finding that very small and very large tumors are less responsive than tumors of intermediate size. ... 

Fulvic acids, an important, intermediate size fraction of natural organic matter, are believed to play an important role in the reduction of metals and organic pollutants. Reduction of Mn(III,IV) oxides (Sunda et al., 1983 Waite et al., 1988) and Fe(III) oxides (Waite and Morel, 1984a Waite and Morel, 1984c Finden et al., 1984) by fulvic acid has been examined extensively, under chemical conditions resembling those in the environment. 

Fg is the partial pressure of the intermediate (atm), dN/dt is the overall reaction rate (mol/s cm ), T is the reaction temperature (K), D is the diffusivity of the medium [cm /s], and R is the catalyst particle size (cm). The intimacy requirements in terms of particle size and partial pressure of intermediate have been calculated. This suggests the constraints that must be applied in forming a dual function catalyst. Guidance is provided for the possible mixing of two particles, for size reduction or the requirement that one catalyst component be added to the other in solution to obtain required intimacy. 

The term grinder describes a variety of size-reduction machines for intermediate duty. The product from a crusher is often fed to a grinder, in which it is reduced to powder. The chief types of commercial grinders described in this section are hammer mills and impactors, rolling-compression machines, attrition mills, and tumbling mills. 

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