Size reduction equipment, selection factors

Also, there are some other factors that influence the selection of the size reduction equipment. These factors are related to process economics (energy... 

Factors Affecting the Selection of Size-reduction Equipment... 

The most important factors that determine the selection of the size-reduction equipment are the mechanical characteristics (shear strength, ductility, etc.) of the feed material, as well as the size distribution of feed and comminuted product. From the aforementioned analysis, it is clear that the mechanical characteristics determine the acting force for size reduction and, consequently, the selection of the proper equipment. The size distribution of the feed stream and product determines the type of the corresponding equipment as well as the dimensions of feed and discharge openings. 

Selection of Size-reduction Equipment. The following factors are determinants in the selection of equipment for size reduction of materials ... 

Figure 14.14. Factors to consider in selecting size reduction equipment for a plastics recycling plant. Adapted from reference 10.

As previously discussed, one of the determinant factors for the right selection of size reduction equipment is consideration of the hardness of the material to be processed. The second factor of great relevance is the required capacity, either fixed or subjected to variations by process requirements. Taking these two main considerations along with a thorough analysis of as many other factors as necessary, flowcharts can be devised to select and locate the most suitable comminution units for a size reduction plant. The combination of different criteria may be summarized in charts, like the one given in Table 4.3, which includes some typical applications of the principal size reduction equipment. 

For the proper selection and economical operation of size-reduction machinery, attention must be given to many details of procedure and of auxiliary equipment. A crusher, grinder, or cutter cannot be expected to perform satisfactorily unless (1) the feed is of suitable size and enters at a uniform rate (2) the product is removed as soon as possible after the particles are of the desired size (3) unbreakable material is kept out of the machine and (4) in the reduction of low-melting or heat-sensitive products, the heat generated in the mill is removed. Heaters and coolers, metal separators, pumps and blowers, and constant-rate feeders are therefore important adjuncts to the size-reduction unit. Factors to consider in specifying a size-reduction system, including energy efficiency and environmental issues, are discussed by Kukla and Hixon, ... 

It is obvious that reduction of the size of the dryer will lead to a reduction in initial capital cost. Although this should not be a deciding factor in the selection of an individual dryer, since only 10 to 15 percent of the life-cycle cost of a direct dryer is due to the initial capital cost of the drying system, it is still an important consideration as it can reduce the space requirement, duct sizes, size of ancillary equipment, etc., as well. One must intensify the drying rates without adversely affecting product quality in order to make the equipment smaller. 

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