Spiral-Conveyor Devices

Spiral-Conveyor Devices Figure 11-60 illustrates the major... 

These devices are replacing the older tank and spiral-conveyor devices. Better provisions for speed and ease of fill and discharge (without powered rotation) minimize downtime to make this batch-operated device attractive. Heat-transfer coefficients ranging from 28 to 200 W/(m °C) [5 to 35 Btu/(h fF °F)] are obtained. However, if caking on the heat-transfer walls is serious, then values may drop to 5.5 or 11 W/(m °C) [1 or 2 Btu/(h fH °F)], constituting a misapplication. The double cone is available in a fairly wide range of sizes and construction materials. The users are the fine-chemical, pharmaceutical, and biological-preparation industries. 

Spiral-Conveyor Devices Figure 11-60 illustrates the major adaptations of this widely used class of material-handling equipment to indirect heat-transfer purposes. These conveyors can be considered for heat-transfer purposes as continuously agitated kettles. The adaptation of Fig. ll-60cf offers a batch-operated version for evaporation duty. For this service, all are package-priced and package-shipped items requiring few, if any, amdliaries. 

Another center-fed design that nas only been usea on a preparative scale is the vertical spiral conveyor column reported by Schildknecht [Angew. Chem., 73, 612 (1961) . In this device, aversion of which is shown on Fig. 22-9, the dispersed-ciystal phase is formed in the freezing section and conveyed downward in a controlled manner by a rotating spiral with or without a vertical oscillation. 

A mechanical device spiral in form or appearance a conveyor working on the principle of a screw a conveying tool in a feeder, mixer, or extruder. Also auger, worm. Extruder in which screw(s) produce the extrusion pressure. 

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