Special Vacuum Drum Filters

Among others, these include those aheady mentioned above, viz. the precoat fdter [11,12], dewaxing fdter [13], single-cell high-capacity vacuum filter [14], compact fdter, pressure-belt drum fdter and so on. 

The compact fdter is a skid type mobile apparatus in which the vacuum fdter already has ad the accessories connected and is thus ready to plug in for instant operation. There are versions available as single-cell filters or as cell filters having ad the usual discharge arrangements, in addition to pre-coat filters with hydrauli-cal lowering filter trough [15]. 

Leading and trailing filtrate pipe on separate control circuits 

Wash separation filter with good separation of mother and wash liquor 

External filtrate pipes with purging air system 

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The press belt drum filter [16] may be defined as a combination of a vacuum drum filter and a pressure stage. It comprises all the standard components of a traditional vacuum drum filter and a press belt attachment mounted on top. The standard components are of reinforced construction to withstand the additional stress imposed by the press belt equipment (up to 251 for a 45-m filter). This continuously operating special filter achieves a medium-specific reduction of the... 

A rotary vacuum drum precoat filter is a specially designed version of the vacuum drum designed to use a thick layer of precoat material to clarify liquid flows. Initially a slurry of the precoat material is prepared and filtered to produce a cake of up to 100mm thickness on the filter cloth. Then the feed trough is drained and refilled with the suspension to be filtered, which is now filtered in the normal way through the precoat layer. The filtered cake can be washed if necessary, and is then discharged by means of a full-width scraper blade. The blade removes the whole of the cake, together with a thin slice (about 0.5 mm) of the precoat layer. 

Raw fermentation broth is an example of a large volume production. Rotary drum vacuum filters (RVF s) have traditionally been found in this service. Slow-settling materials or more difficult filtrations with large scale production requirements are typical applications for this type of equipment. For an overview of filter selection versus filtering rates, see Table 3, which is excerpted by special permission from Chemical Engineering/Deskbook Issue, February 15, 1971, by McGraw Hill, Inc., New York, NY 10020. 

The Oliver precoat filter is a modification of the regular Oliver filter. It consists of a horizontal cylindrical drum, the outside pf which is made up of separate segments or compartments. The entire outside of the cylinder is covered with a filtering medium such as fine mesh wire or cloth. Each segment is connected to a discharge line, under vacuum, by a special valve on the end of the drum in such a way that suction is maintained while the drum rotates. A deposit (or precoat) of diatomaceous earth or Ref. Nat. Oaso. Mfr., February, 1934, p. 54. 

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