Rotary vacuum filter replacement drum series#
A series of 1/2 inch spaced strings rest on the filter medium at the two o'clock position. This is the primary method for starch and mycelia applications. Difficult filiations requiring thinner cakes incorporate a string discharge mechanism. Friable, dry materials can use a "doctor" blade as in Fig. Once formed, the cake dewaters above the submergence level and is then washed, dewatered and discharged.ĭischarge mechanisms will vary depending upon cake characteristics. Cake formation occurs during submergence. The applied vacuum draws the suspension to the cloth, retaining solids as the filtrate passes through the cloth to the inner piping and, subsequently, exiting the system to a vapor-liquid separator with high/low level control by a pump. As the drum rotates, a panel is submerged in the slurry. The drum is positioned in a trough containing the agitated slurry, whose submergence level can be controlled.
Membranes can yield more complete filtration clarification, but often a wetter cell paste. Although still widely used, rotary vacuum filters are, in some cases, being replaced by membrane separation technology as the method of choice for clarification of fermentation broths and concentrating cell mass. With the exception of the precoat applications, RVF's do not usually yield absolutely clear filtrate. Moisture levels are, of course, dependent upon particle size distribution and tend to range from 25% to 75% by weight and cake thickness tends to be in the 1/8-1/2 inch range, as most applications are for slow-filtering materials. The cylinder is divided into compartments like pieces of a pie (see Fig 2), and drainage pipes carry fluid from the cylinder surface to an internal manifold.įilter diameters range from three to twelve feet, with face lengths of one to twenty-four feet, and up to 1000 ft2 of filtration area.[5 J Filtration rates range from 5 GPH per square foot to 150 GPH per square foot.