Machine and application development

Basic decanter performance (in terms of solids recovery, centrate quality and solids dryness) remained relatively little changed in this period, but improving engineering and materials of construction enabled the use of longer bowls to give greater feed capacity. 

Of the major design variants (all described in Chapter 2), the screen-bowl design was developed by Bird in the mid-1940s. Sharpies produced the first vertical, pressurisable decanter in 1958. and three-phase operation came along in the early 1960s. 

In the subsequent 30 years, relatively few new applications have been developed, with the difficulty of achieving fully sanitary operation keeping the decanter from some of the food and biochemical operations. However, major changes have occurred in the refinement of machine design, and, therefore, performance. 

These changes have been most apparent in the way in which the decanter handles the discharging solids, and especially in the achievement of the maximum dryness (least moisture content) in those solids. Thus there are restrictions available at the base of the conical section (such as Sharpies Centri-Seal patent by Lee), operations with deep ponds, and improved control over conveyor speed and torque, leading to the Dry Solids decanter. 

The availability of stronger stainless steels has enabled the production of very long bowls, as well as quite large diameter bowls. Very high rotational speeds are now available, giving separational forces of up to 10 000 times the force of gravity on smaller models. 

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