Multicyclone Arrangements

There are many situations wherein one cyclone or swirl tube is inadequate for the separation task at hand. In such situations, it is often feasible to use multiple units either in series or in parallel or both. 

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Figure 13.B.1 depicts a parallel ( multicyclone ) arrangement of six demisting cyclones, with each cyclone discharging its overhead vapors into a common attic chamber and its underflow liquid into a common pool of liquid. The two front cyclones take their feed from the near-wall regions of the inlet duct. The two back cyclones take their feed from the centermost section of the inlet ducting. The middle cyclones take their feed from that section of the inlet...

The three installations shown in Figs. 16.2.2 and 16.2.3 illustrate only a few of many possible multicyclone arrangements. Each equipment designer... 

One commercially available system comprising a parallel arrangement of cyclones, called swirl tubes , is the multicyclone unit illustrated in Fig. 16.2.2. The solids-bearing feed stream enters the separator vessel via a centrally located pipe at the top of the vessel. The feed exits this inlet pipe near its bottom end from where it flows radially outwards - between two tube sheets - and into the feed chamber or plenum. The solids-bearing gas then enters the individual swirl tubes wherein it is split into a solids-laden underflow stream and a clean-gas overflow stream. 

Figure 16.2.3 shows another commercial multicyclone featuring closely spaced individual swirl tubes arranged on a tube sheet but fed from one side of the tube array. 

A true multicyclone is not only a parallel arrangement of cyclones, but also one wherein the individual cyclones are housed within a common casing that constitutes the inlet chamber. Furthermore, the dust (or liquid) discharge and the gas outlet pipes also report to their own common outlet plenum and hopper, respectively. Multicyclone systems of the type shown in Figs. 16.2.2 and 16.2.3 are usually comprised of numerous small diameter cyclones (typically under 250 mm in diameter) and this normally leads to excellent separation performance relative to fewer, larger units handling the same total volumetric flow. 

Fig. 16.2.3. Left a Cyclo-TrelF Multicyclone unit featuring a closely packed arrangement of parallel swirl tube type cyclones. Courtesy Hamon Research Cottrell. Right Simplified view of a multicyclone showing upper and lower tubesheets...

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