Mechanical Design of Mixing Equipment

Mixing equipment must be designed for mechanical and process operation. Although mixer design begins with a focus on process requirements, the mechanical design is essential for successful operation. Usually, a competent manufacturer of mixing equipment will take responsibility for the mechanical design. However, process conditions, such as impeller operation near a liquid surface, can impose severe mechanical loads. Similarly, the process environment will influence the selection of a motor enclosure. In many ways the process requirements can have a direct impact on the mechanical design. In other ways, such as the natural frequency of a mixer shaft, appropriate mechanical design must be determined by the equipment designer. Whatever the reason, knowledge of the mechanical requirements for a mixer will help guide the engineer toward a design that will meet both process and mechanical criteria. The purpose of this chapter is to provide practical information about the mechanical design of mixing equipment. Therefore, descriptions, equations, and nomenclature will be given in both U.S. engineering units and metric units. Descriptions and equations using U.S. engineering units will follow common industrial practices used in the United States with design information for materials measured in inches and motors specified in horsepower. Descriptions using