Vacuum drum filters applications

Filtration is a unit operation commonly employed nowadays in biotechnological processes. In this unit operation, a filter medium acts as a physical barrier to particles larger than its pores. Traditional filtration devices such as filter presses and rotary vacuum drum filters have so far found no application for the separation of animal cells. Nevertheless, membrane filters are commonly employed, as well as some alternative filter designs such as spin-filters. In the next sections, the most common types of filters used for animal cell separation will be discussed. 

Vacuum drum filters, 319 air flow rates, 328 applications, 332 cycle design, 328 flowsketch, 326 laboratory test data, 312 minimum cake thickness, 328 operation, calculation example, 312,... 

Parts which do not come into contact with the product are made of steel and may also have an appropriate corrosion-resistant paint coating. For hght-duty applications, vacuum drum filters with main components made of plastic are also used. 

Slurries of free-filtering sohds that are difficult to suspend are sometimes filtered on a top-feed drum filter or filter-diyer. An example application is in the production of table salt. An alternative for slurries of extremely coarse, dense solids is the internal drum filter. In the chemical-process industiy both top-feed and internal drums (which are described briefly by Emmett in Schweitzer, op. cit., p. 4-41) have largely been displaced by the horizontal vacuum filter (q.v). 

Filter application Continuous vacuum filters Multicompartment drum Single compartment drum Top feed drum Scroll discharge drum Tilting pan Belt Disc... 

Disc filters are similar in principle to rotary filters, but consist of several thin discs mounted on a shaft, in place of the drum. This gives a larger effective filtering area on a given floor area, and vacuum disc filters are used in preference to drum filters where space is restricted. At sizes above approximately 25 m2 filtration area, disc filters are cheaper but their applications are more restricted, as they are not as suitable for the application of wash water, or precoating. 

In the dewatering of flotation concentrate slurries, produced during mineral dressing operations, and in similar processes, the objectives are to recover the maximum amount of solids, produce saleable products where possible, and thus increase plant capacity at the most economic cost. There has been a significant improvement in process efficiency in this application by the use of belt discharge drum filters in place of disc vacuum filters and string/scraper drums. 

Horizontal belt filters working on the vacnnm principle were originally developed for process applications where intensive washing is required, but are now also employed for a wide variety of filtering reqnirements. They have become such a versatile processing tool that they have taken a considerable share of the market from the former workhorse of the vacuum filter business, the rotary drum filter, and also quite a share from traditional filter press applications. 

This equipment consists of a horizontal axis revolving drum. The surface of the drum is segmented, with compartments fitted with drainage pipes leading inside the drum to a common manifold and a rotary valve located at one end of the drum. A filter medium is attached to the external surface of the drum. When the drum is mounted with part of its surface in a tank of slurry, the application of a vacuum behind the filter medium pulls the filtrate through. The solid material is retained on the filter surface and, as the drum turns slowly past a knife, is dislodged into a collection hopper for disposal or further treatment. 

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