Vortex finder design

The vessel design features a Chinese hat-like conical core stopper above the underflow sump, which is there to prevent the vortex from reaching the latter and reentraining the settled soHds. The core stopper is also beheved to stabilize and locate the vortex flow in the vessel. Overflow from the vessel is through a wide cylindrical insert through the Hd, similar to a vortex finder in a hydrocyclone (16), and an optional provision can be made for collecting any floatables in a float trap. 

For a properly designed and operated cyclone, the sharpness iadex is constant, typically 0.6. The cut size and apparent bypass are a function of the cyclone geometry, the volumetric feed rate, the material relative density, the feed soflds concentration, and the slurry rheology. The relationship for a standard cyclone geometry, where if is the cylinder diameter ia cm and inlet area = 0.05 vortex finder diameter = 0.35 ... 

The flow rate to the hydrocyclones for the full-scale SILVER II unit, based on a 14-mm vortex finder and a 6.4-mm underflow spigot, would need to be approximately 3.2 m3/hr at a pressure of around 3.5 bar. This flow rate should be sufficient to achieve the overflow flow rate of 1.8 m3/hr required to feed the SILVER II cells. As noted previously, the hydrocyclones used in the 12-kW energetics and agent simulant trials for EDS II handled solids at the planned design loading (AEA, 2001a). 

There are a number of different forms of cyclone but the reverse flow cyclone represented in Fig. 1 is the most common design used in the industry. The cyclone consists of four main parts the inlet, the separation chamber, the dust chamber and the vortex finder. Tangential inlets are preferred for the separation of solid particles from gases [1]. In this study, the numerical simulation deals with the standard case of reverse flow cyclone with a tangential rectangular inlet. Cyclone dimension used in this simulation are as shown in Table 1. 

The key design variables are defined as those that are associated with the hydrocyclone dimensions, including cyclone diameter, D, inlet diameter, D, outlet (apex) diameter, D, and vortex finder diameter, D. In addition, the total length of the cyclone, L, the length of the cylindrical section, /, and the cone angle, 6, are also important. They all affect the operating performance of the hydrocyclone. 

Hydrocyclone. When only water is used in a cyclone for cleaning coal, it is called a hydrocyclone. Hydrocycloning has been applied even to process coal finer than 0.5 mm. Its design differs from that of the dense-medium cyclone by having a greater cone angle and a longer vortex finder. 

Fig. 12.1.3. Vortex finder in line-of-sight of incoming gas/solids mixture and design techiques to avoid this condition. CFX image courtesy of USDA Agricultural Research Service, Southwestern Cotton Ginning Research Laboratory and New Mexico State University...

Most cyclones are designed with flat roofs. Under high pressure or high vacuum conditions, however, it is sometimes necessary to fabricate a cyclone with a domed roof. Typically, such a roof is either elliptical or hemispherical— depending on such factors as the differential pressure across the roof, wall thickness, the size of the cyclone, and the relative vortex finder-to-barrel diameter. In such instances, it is recommended that a fiat false or inner roof be installed (and properly vented if necessary) so that the flow pattern is the same as that of a conventional flat-headed cyclone. 

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