Cyclone separators Hydroclones

Six-tenths factor, 47 Yearly cost indices, 47 Critical flow, safety-relief, 438 Back pressure, 440 Sonic flow, 438 Critical flow, see Sonic Cyclone separators, 259-269 Design, 260-265 Efficiency chart, 263 Hydroclones, 265-267 Pressure drop, 263, 264 Scrubber, 269 Webre design, 265 Deflagration venting nomographs,... 

Related Calculations. This method can be used for determining separation effectiveness for classifying screens, elutriators, cyclones, or hydroclones in which a known feed of a known crystal size distribution is segregated into a fine and a coarse fraction. If a cut size cannot be predetermined, assume one at a time and complete the described effectiveness analysis. The assumed cut size that gives the largest effectiveness is the cut size that best describes the separation device. 

Use a cyclone separator to remove, from a gas, droplets or solid particles of diameter down to 10 microns (0.01 mm). Use a hydroclone separator to remove, from a liquid, insoluble liquid droplets or solid particles of diameter down to 5 microns (0.005 mm). However, small amounts of entrained liquid droplets are commonly removed from gases by vertical knock-out drums equipped with mesh pads to help coalesce the smallest droplets. 

The use of cyclones or other separators, in the sampling mode, for on-line particle size measurement is now well established in both dry and wet applications . This involves taking a continuous sample stream through a small cyclone or hydroclone under a given set of operating conditions, and monitoring the recovery of the cyclone. The task of particle size measurement is thus reduced to measurement of solids concentrations in two material streams. 

In determining the proper size and number of cyclones required for a given application, two main objectives must be considered. The first is the classification or separation that is required, and the second is the volume of feed slurry to be handled. In the case of hydroclones, before determining whether these objectives can be achieved, it is necessary to establish a base condition as follows Feed liquid - water at 20 C. Feed solids - spherical particles of 2.65 specific gravity Feed concentration - less than 1 % solids by volume Pressure drop - 69 kPa (10 psi) Cyclone geometry - "standard cyclone" as described above. 

The separation that a cyclone/hydroclone can achieve can be approximated from the following relation. The 0 50 (base) for a given diameter cyclone is multiplied times a series of correetion faetors designated by C, Cj, and C ... 

As an example - to produce an overflow of 80 % passing 149 p (100 mesh), the multiplier from Table 3 at 80 % passing is 1.25. The micron size for the application is 149 p (100 mesh). The D50c required = 1.25 x 149 = 186 p for the application. The separation that a cyclone/hydroclone can achieve can be approximated from the following relation. The Dc50 (base) for a given diameter cyclone is multiplied times a series of correction factors designated by C, C2, and C3 ... 

Hydroclones were introduced in 1891 to remove sand from water. They function like a gas-solid cyclone, have no moving parts, and rely on centrifugal force for separation, clarification, and dewatering processes. Hydroclones find use in concentrating slurries, in classifying solids in liquid suspensions, and in washing solids. They may be used alone or in conjunction with clarifiers, thickeners, or filters (Besendorfer, 1996). 

The pressure drop Ap in a hydroclone varies with the feed rate raised to a power between 2.0 and 3.3. For dilute feeds the cut diameter varies with the 1.5 power of the cyclone diameter, so for a given pressure drop a small diameter gives better separation than a large one. Hydroclones are therefore small they range in diameter from 10 mm (0.4 in.) to about 1.2 m (48 in.). To handle large flows, many small hydroclones are connected in parallel, with as many as four hundred and eighty 10-mm units manifolded in a single assembly. 

The liquid-solid hydrocyclone, shown schematically in Fig. 3.4-3, functions like a gas-solid cyclone. The hydrocyclone is also known as a hydroclone. The primary independent parameters that influence the ability of a hydrocyclone to make a separation are size and geometry of the hydrocyclone, particle size and geometry, solids loading, inlet velocity, split between overflow and underflow, density differential, and liquid viscosity. A reasonable estimate of Ae particle cut diameter (50% in underflow and overflow) d o) is given by the following dimensionless relationship, developed initially by Bradley ... 

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