Rotary disc

Typical uses. Continuous larger scale separation of relatively free filtering suspensions where washing is not required. 

FDSprocess ratings 4 C, 6, 8 (cloth covered disc) 4 C, 9, 8 (ceramic disc). 

Typical particle size and feed concentration range 1-700 pm and 5-20% w/w. 

Rotary disc filters are available at a relatively low capital cost with total cloth areas between 0.05 and 300 m. They have an inherently large filter area to floor space ratio and their flexibility is enhanced by an ability to process multiple feedstocks at the same time within a single unit. 

In the Ceramec variant, the filter cloths and supporting porous plates are replaced by sintered alumina membranes with near uniform micropores. Although a relatively small vacuum pump is needed to promote cake formation, cake deliquoring proceeds via capillary action with little or no air 

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A wide variety of extraction column forms are used in solvent extraction applications and many of these, such as rotary-disc contactors (RDC), Oldshue-Rushton columns, and sieve-plate column extractors, have rather distinct compartments and a geometry, which lends itself to an analysis of column performance in terms of a stagewise model. As the compositions of the phases do not come to equilibrium at any stage, however, the behaviour of the column is therefore basically differential in nature. 

Rotary annular columns and rotary disc columns... 

A rotary disc (RD) pertractor with BLM was suggested in refs. [48, 49]. In a RD pertractor hydrophilic discs are fixed on a rotating horizontal shaft. The lower parts of the discs are immersed in compartments, which are alternately filled with the stripping solution and the feed. The remaining parts of the discs, on which films of aqueous phases are formed due to rotation, are immersed in the membrane phase. 

Formation of spray in small drops (i.e. 30 microns, with a narrow size distribution) using a rotary disc or nozzle, to enhance the product-air interface. The preparation of the feed (dry matter content, composition, temperature, mixing) must facilitate pumping and spraying with minimal modification (partition of constituents, droplet coalescence in emulsions). 

Vehicle-mounted (with cab) and rotary disc atomizers volume of surface contamination, 2mL/h inhalation exposure, 0.005 mL/h ... 

Vehicle-mounted (without cab), air assisted and rotary discs volume of 50L/ha volume of surface contamination, 20 mL/h 0.02 mL/h, with application inhalation exposure. 

They also examined a large number of authentic cut crystal and hard-stone artifacts from documented Olmec, Maya, Aztec, and Mixtec contexts for comparative purposes. The SEM results showed for the British Museum skull unambiguous evidence of high-speed rotary disc cutting and the use of exU emely hard abrasives. Although diamond and corundum are two naturally occurring abrasives of adequate hardness, they were not in use in ancient Mesoamerica and the authentic artifacts showed no such SEM evidence. 

Teunou E, Poncelet D (2005) Rotary disc atomisation for microencapsulation applications—Prediction of the particle trajectories. Journal of Food Engineering 71 345-353. 

L. Huang, K. Kumar, A.S. Mujumdar, A comparative study of a spray dryer with rotary disc atomizer and pressure nozzle using computational fluid dynamic simulations, Chemical Engineering and Processing, 45 (2006) 461-470. 

Figure 11.5 Rotary disc filter (Courtesy of Gaudfiin SA, St. Germaine-en-Laye, France)...

It is also observed that filter cake washing effidencies can be low in these filters. Such effects are attributed to maldistribution of wadi water sook of the latt inevitably cascades over the cake sur ce, to be collected in the feed trou As befine, the limited time for washing is also a problem. In some cases, two stages (or nmre) of fihrarion may be conddered, wiffi intat age, re-duiry washing. Ibese con onents also appfy to rotary disc filters discussed in the next section. 

For spray drying, the cell suspension is pumped as liquid concentrate to the dryer and separated in small droplets by means of a pressure nozzle (one or two fluid nozzles) or a rotary disc. The mode of particle formation in the drier also influences the viability of the bacteria after drying (Ghandi, Powell, Chen, Adhikari, 2013). A schematic spray drier is shown in Figure 11.6. 

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