Mechanical separation equipment costs

The overriding consideration in the selection of drying equipment is the nature and concentration of the feed. Drying is an energy-intensive process, and the removal of liquid by thermal drying will be more costly than by mechanical separation techniques. 

Filtration separates cells from a fluid by forcing the fluid through a porous filter medium, which deposits solids as liquids pass through. Vacuum or positive-pressure equipment is used to create the driving force for filtration. The main advantages of filtration include high rates of separation, low cost, mechanical simplicity, and relative ease of maintenance. However, it can have a low retention or poor containment, and can require the addition of a filter aid to ensure good filtration when solids accumulate on the membrane. 

Phase separation is controlled by phase equilibrium relations or rate-based mass and heat transfer mechanisms. Chemical reactions are controlled by chemical equilibrium relations or by reaction kinetics. For reactive distillation to have practical applications, both these operations must have favorable rates at the column conditions of temperature and pressure. If, for instance, the chemical reaction is irreversible, it may be advantageous to carry out the reaction and the separation of products in two distinct operations a reactor followed by a distillation column. Situations in which reactive distillation is feasible can result in savings in energy and equipment cost. Examples of such processes include the separation of close-boilers, shifting of equilibrium reactions toward higher yields, and removal of impurities by reactive absorption or stripping. 

The first step in the process is risk identification, which is accomplished by review of the proposal/study by suitably experienced experts using well-considered checklists. These must embrace all facets which may affect the project outcome, such as plant feedstock quality, process reliability, mechanical reliability, potential foundation problems, operational hazards, environmental impact, equipment costs, construction costing and labour, statutory requirements, contractual and legal problems peculiar to the country of construction, eventual decommissioning costs, and so on. Risks due to operational hazard are generally treated separately from commercial risk, and will be discussed in Chapter 12, but they are obviously an essential part of the overall process. 

With few exceptions, treatment technologies are limited to some extent by the size of the material that they are able to process. These limitations can apply to the throat of the feed devices, the inner workings of the equipment, the treatment mechanisms, or the process elements. To make these remedial technologies efficient and cost effective, separation techniques are used to make the feed stream uniform... 

Because of the magnitude of the task of preparing the material for this new edition in proper detail, it has been necessary to omit several important topics that were covered in the previous edition. Topics such as corrosion and metallurgy, cost estimating, and economics are now left to the more specialized works of several fine authors. The topic of static electricity, however, is treated in the chapter on process safety, and the topic of mechanical drivers, which includes electric motors, is covered in a separate chapter because many specific items of process equipment require some type of electrical or mechanical driver. Even though some topics cannot be covered here, the author hopes that the designer will find design techniques adaptable to 75 percent to 85-1- percent of required applications and problems. 

As a general rule, the use of organic solvents in chromatographic processes should be minimized, because of the requirement for specialized flameproof equipment which can be extremely costly compared with the equivalent item for a safe area. Where unavoidable, a separate flameproof room for handling solvent-based materials is recommended, with the appropriate specification for mechanical and electrical equipment, controls and room fittings including lights, switches, and telephone systems. 

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