Schildknecht column

Whilst the Schildknecht column is essentially a laboratory-scale unit, a melt-crystalliser of the wash-column type was developed by Phillips Petroleum Company in the 1960s for large-scale production of xylene. The key features of this Phillips pulsed-column crystalliser, as described by McKay et alSss are shown in Figure 15.27. A cold slurry... 

Schildknecht Column [Fig. 16.14(a)]. This employs a rotating spiral or screw to move the solids in the direction against the flow of... 

Scatchard-Hildebrand equation, 374 Schacham equation, friction factor, 94 Scheibel extractor, 483,487 Schildknecht column, 543,544,546 Screens, separating, 335, 337 capacity, 335, 340 flat, 335... 

Drum cascades are not found in large scale. Schildknecht columns never did work when they were too large (larger than laboratory scale), due to problems with axial back mixing and scaling. Since the Brodie purifiers only worked in a few special cases, the TSK process was created. At first glance, the TSK process appears to be continuous, but it is, in fact, a cascade of crystallizers with a purification column. The Kureha purifier and the Nippon Steel BMC work within their companies for special cases or products. 

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. 

The idea of a column was followed by Schildknecht (see, e.g., Maas and Schildknecht 1963) in many papers. The column was fed in the center and used a spiral conveyer to transport the crystals upward countercurrently to melt through the purification zone. 

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