Thin layer solid bowl centrifuge

Consider a thin layer solid bowl centrifuge as shown in Figure 4.20. In this device, particles are flung to the wall of the vessel by centrifugal force while liquor either remains stationary in batch operation or overflows a weir in continuous operation. Separation of solid from liquid will be a function of several quantities including particle and fluid densities, particle size, flowrate of slurry, and machine size and design (speed, diameter, separation distance, etc.). A relationship between them can be derived using the transport equations that were derived in Chapter 3, as follows. 

The conical discs in a disc bowl centrifuge split the liquid flow into a number of very thin layers, which greatly increases the separating efficiency. Disc bowl centrifuges are used for separating liquids and fine solids, and for solids classification. 

The centrifuge contains a stack of conical disks spaced between 0.5 and 2 mm apart. The feed is supplied through a pipe to the center of the bowl at the base of the machine and is distributed into many thin layers. The different phases therefore have only a very short distance to travel to free themselves from each other. Once the solids have contacted the underside of the disks, the settling process is over and the solids move to the periphery of the disks, where they are thrown off the edge onto the bowl wall. 

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