Cyclones reverse-flow

FIGURE 13.1 A schematic diagram of a classical reverse-flow cyclone. 

Table 12-1 Standard Designs for Reverse Flow Cyclones...

Circulating Beds These fluidized beds operate at higher velocities, and virtually all the solids are elutriated from the furnace. The majority of the elutriated sohds, still at combustion temperature, are captured by reverse-flow cyclone(s) and recirculated to the foot of the combustor. The foot of the combustor is a potentially very erosive region, as it contains large particles not elutriated from the bed, and they are being fluidized at high velocity. Consequently the lower reaches of the combustor do not contain heat-transfer tubes and the water walls are protected with refractory. Some combustors have... 

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 most commonly used design is the reverse-flow cyclone, as shown in Figure 10.43 other configurations are used for special purposes. In a reverse-flow cyclone, the gas enters the top chamber tangentially and spirals down to the apex of the conical section it then moves upward in a second, smaller-diameter spiral, and... 

FIGURE 20 Schematic of reverse flow cyclone flow configuration. 

FIGURE 53.1 Shape and dimensions of reverse-flow cyclone. 

Figure 53.1 shows a typical reverse-flow cyclone in which the necessary elements consist of a gas inlet that produces the vortex an axial outlet for cleaned gas, and a dust-discharge opening. There are a number of different arrangements and modiflcations that offer variations in performance and overcome some of the limitations of the conventional reverse-flow cyclone. These modiflcations can be summarized according to the following classifications [18] ... 

Cyclone Design Configurations (Reverse-Flow Type) ... 

Finally, reversible-flow cyclones can be used for gas cleansing. These have the highest turndown ratio and good efficiency versus drop size (commercial claim 3 + pm, depending on design). They do, however, have a pressure drop higher than that of vane packs and axial flow cyclones. 

Gas-liquid (gas dominated) separation done by axial-and reverse-flow cyclonic devices operating at 20-200 g. These are also used for polishing at gravity separator gas outlets. 

Sand-liquid separation done by reverse-flow cyclonic devices operating at 10-500 g. These have been commercially available in the mining industry for a long time, and are extensively used for sand cleaning in the offshore industry... 

Figure 1.9 Cross-section through a reverse-flow hydrocyclone showing the typical flow patterns. The inset photograph (Axsia-Mozley) shows a bank of six cyclones connected to a common feed manifold system.

The most common type of cyclone is known as the reverse flow type (Figure 9.2). Inlet gas is brought tangentially into the cylindrical section and a strong vortex is thus created inside the cyclone body. Particles in the gas are subjected to centrifugal forces which move them radially outwards, against the inward flow of gas and towards the inside surface of the cyclone on which the solids separate. The direction of flow of the vortex reverses near the bottom of the cylindrical... 

Figure 9.2 Schematic diagram of a reverse flow cyclone separator...

Figure 9.7 Total separation efficiency and pressure drop versus gas flow rate through a reverse flow cyclone...

The following practical considerations for design and operation of reverse flow gas cyclones are among those listed by Svarovsky (1986). 

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