Continuity, hydrocyclones

A second separation process reported by EBC is based on the use of hydrocyclones. Stable emulsions formed by good oil-cell-water contact and mixing can be separated continuously with hydrocyclones to obtain relatively clean oil and water. A method and an apparatus for separating a water/organic/solid emulsion, wherein the solid comprises particles having a length of about 50 xm or less, has been disclosed [267], This separation process scheme is shown in Fig. 14 and as before the separation method is envisioned as part of a BDS process. 

An emulsion separation method using hydrocyclones. The emulsion comprises a continuous phase, a discontinuous phase and fine solid particles. In the first step, the original emulsion is separated into an overflow emulsion and an underflow emulsion, in a first hydrocyclone. The overflow emulsion comprises portions of the continuous phase, the discontinuous phase and the fine solid particles. The overflow emulsion is inverted in which the continuous phase of the overflow emulsion is now a second discontinuous phase and the original discontinuous phase becomes a second continuous phase. Then, the inverted emulsion is directed to one or more subsequent hydrocyclones and the second continuous and discontinuous phases are collected. The fine solid particles remain in the second discontinuous phase. 

There is a clear need for other size classifiers which combine a high separation efficiency with flexibility and compactness. Hydrocyclones have a small volume, are simple in operation and are standard size classification equipment, for example in closed circuit grinding applications. The recent development of the flat-bottom hydrocyclone, which permits classification in the coarse size range, creates an additional motive to study the use of hydrocyclones for Crystal Size Distribution (CSD) control. Furthermore, throttling of a flat botom hydrocyclone does not necessarily provoke blockage but allows continuous control of its cut size when a controlled throttling valve is used. There is a clear incentive for its use in this application since it may provide an additional process input. 

Du, B., Warsito, W., and Fan, L.-S. Ind. b Eng. Chem. Res. 44(14), 5020-5030 (2005). Dyakowski, T., and Williams, R. A., Hydrocyclone flow modeling—a continuous research challenge, Chapter 5, in "Innovation in Physical Separation Technologies Richard Mozley Symposium Volume, The Institution. Mining Metallurgy, London, pp. 61-73... 

Wet classification is performed by filtration, settling, centrifugation, Sind hydrocyclones. When operated in conjunction with grinding equipment, the wet classification equipment must operate continuously and give a pumpable fluid. This is often accomplished in practice with hydrocyclones because the other methods are unsuitable (e.g., settlers and centrifuges are used for dilute suspensions, filters and screens produce a nonpumpable cake.)... 

FIGURE 4.18 (Continued) (c) Predicted particle volume fraction for 35% weight CaCOs powder in a 75-mm hydrocyclone, (d) Experimental and predicted size selectivity curves for 35% weight CaCOg powder in a 75-mm hydrocyclone (the interactions correspond to viscosity corrections made for the particle volume fraction distribuiuBi within the hydrocyclone). From Rcgamani and Mifai [48]. 

Osborne [25] described a sampler that consists of a narrow slot continuously rotated on an axis parallel to the slun7 flow (Figure 1.35a). Cross [26] used a slotted pipe mounted vertically in the overflow compartment next to the vortex finder of a hydrocyclone (Figure 1.35c). 

A complete circuit for an advanced scrubber is shown in Fig. 4, which includes oxidation of the sludge to form gypsum. In this circuit, limestone is first reduced to a fine particle size by a grinding mill, producing a slurry. The slurry is then added to the absorber tank, and pumped into the scrubber tower. A portion of the descending absorbent is diverted back to the absorber tank, which provides more time for the sulfur dioxide and limestone to react. The remaining absorbent collects in the base of the tower, where it is oxidized by injected air while being recirculated in the lower portion of the scrubber. A portion of the absorbent is continuously drawn off to a hydrocyclone. 

Sedimenting centrifuges Filtering centrifuges Hydrocyclones Deep-bed filters Cartridge filters Pressure vessel filters Filter presses Continuous filters Gravity separation equipment... 

Solving the problem on the interaction of a solid particle, drop, or bubble with the surrounding continuous phase underlies the design and analysis of many technological processes. The industrial applications of such interaction include classification of suspensions in hydrocyclones, sedimentation of colloids, pneumatic conveyers, fluidization, heterogeneous catalysis in suspension, dissolving solid particles, extraction from drops, absorption, and evaporation into bubbles [69, 107, 111, 122,137,478,505],... 

A different situation arises for hydrocyclones, in which the density of the disperse phase is only moderately greater than the density of the continuous phase. Therefore, for hydrocyclones, < 1, and their CE (Eig. 19.4, b) is small and essentially depends on the profile of the tangential flow velocity. From the three laws of swirling considered above, the greatest efficiency is provided by the law of quasi-solid rotation. 

Miscellaneous Continuous After burner, cyclone, demister, dust collector, ejector, hydrocyclone, steam jet... 

Continuous wet classifiers, of the rake and spiral type, and hydroclones (hydrocyclones) can also produce concentrated slurries, but the overflow liquid is not clear, containing the smaller particles. A separation of particles by size and density occurs. Hydroclones are inexpensive, typically 6 in. in diameter or less, and a single unit can handle only low flow rates. For high flow rates, parallel units are employed in a multiclone. Table 16.32 contains f.o.b. purchase costs for wet classifiers and hydroclones. The size factor is the solids flow rate for classifiers and the liquid flow rate for hydroclones. 

To recover liquid in order of preference of settlers, Section 5.8, thickeners. Section 5.10 and sedimentation centrifuges. Section 5.12 clarifier, settler, washing tray thickener, reactortubular bowl centrifuge, batch automatic (horizontal or vertical bowl, disc with intermittent nozzle discharge) continuous disc bowl centrifuge with nozzle discharge. 

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