Swirl tube design

In both cases, the bottom boundary condition was simply a no flow-through condition. The bottom configuration varies in swirl tube designs some swirl tubes discharge directly to a wider hopper without any bottom plate. Such an arrangement does not encourage gas to suddenly turn inwards at the bottom of the main body cylinder. 

FIGURE 7.12 Simplified schematic diagram of cyclone foam breaker. (With kind permission from Springer Science+Business Media Gas Cyclones and Swirl Tubes Principles, Design and Operation, Foam-breaking cyclones, 2008, p 327, Hoffmann, A.C., Stein, L.E., Chapter 14.)... 

Equation (3.3.2) is especially useful to the plant engineer who wishes to estimate the pressure loss through his or her cyclone system at conditions other than design conditions, or at some fiow rate other than one for which the pressure loss is known. We shall see how in Chap. 8, where also the derivation of this and other dimensionless numbers characterizing cyclones and swirl tubes can be found. 

Obviously this model has some restrictions in its range of applications. As the model stands, it is only suitable for cyclones with slot inlet and a low loading. This is because the effect of the dust on the wall on the friction factors is not reliably quantified as the authors state. If the effect of the solids is to be accounted for, the friction factors at the different walls are likely to differ. Another restriction is that it is only applicable to the conventional cylinder-on-cone cyclone design, and therefore not to cylindrical swirl tubes. 

The following sections will show that the vortex end significantly influences the behavior of cyclones and swirl tubes. Its nature, and the factors governing its position, should therefore be well understood by anyone who designs such cyclonic type separators, and this topic should be given high priority in cyclone research at this time. 

The second cyclone body shown in Figure 13.3.4 illustrate a vane-type inlet design that we refer to herein as a swirl tube separator. Vane inlets are the most symmetrical of all inlet designs but are somewhat more comphcated to design and fabricate or, in some cases, to cast. Both the twin inlet and vane inlet cyclone designs described thus far are of the conventional reverse-flow variety. 

This completes our look at the design of cylinder-on-cone cyclones with tangential inlets. In the following section we discuss the design of cylindrical swirl tubes with swirl vanes. In this discussion, we concentrate on the aspects that are specific to swirl tubes. For the aspects shared between swirl tubes and tangential entry cyclones, much of the discussion above is equally valid for swirl tubes, such as the discussion pertaining to vortex finder configurations. 

Design of Swirl Tubes with Swirl Vanes... 

The design of swirl tubes features much less prominently in the hteratme than cylinder-on-cone cyclones. The main design features specific to swirl tubes are the inlet vanes, the length of the swirl tube body and the configuration of the... 

Figure 15.2.1 shows a cylindrical swirl tube with swirl vanes. We will look at the effects of two aspects of vane design the shape of the vanes—in particular the entrance and exit angles—and their thickness and number, which determines the area available for flow and, therefore, the velocity in the vane-pack. In this discussion we will often refer to the individual vane elements comprising the vane assembly as a blade element , vane element , or simply blade or vane . 

Gas Cyclones and Swirl Tubes—Principles, Design and Operation is a valuable and necessary work in the field of gas cyclones. It will become a classic in this field because of the comprehensive manner in which it covers the study and usage of cyclones. In addition, this work provides unbiased presentations of the many theories used to describe and calculate the performance of cyclones, empirical methods of cyclone design, and the practical aspects of using cyclones. 

New material on the end-of-vortex phenomenon in reverse flow cyclones and swirl tubes is given in Chapter 9. Chapters 10 and 11 emphasize the importance of base-line performance of a new cyclone, tracer measurements, and post-separation problems including hopper design. Prudent advice is given regarding suggested focus on underflow mechanics when operational problems arise. Substantial changes were made in Chapter 12, with new material and illustrations added on erosion of the vortex finder s outer wall in view of recent CFD results, and use of wetted walls, sprays, and electrostatic fields in cyclones. 

Cyclone inlet section. As the mist-laden gas enters the separator, the entrained liquids and solid particles are subjected to centrifugal force. The gas enters the cyclone tube at two points, designated A, and sets up a swirling motion. Solid and liquid particles are thrown outwardly and drop from the tube at point B. The swirling gas reverses direction at the vortex C and rises through the exit portion of the tube, designated D. See Fig. S-21. 

The use ofswirl flow, whereby a rotational vortex is imparted to the boihng fluid to centrifuge the liquid droplets out to the tube wall, has proved to be the most reliable means to correct for and eliminate this loss of AT. The use of this technique almost always corrects the design to operate as well as or better than predicted. Also, the use of swirl flow eliminates the need to determine between horizontal or vertical orientation for most two-phase velocities. Both orientations work about the same in swirl flow. 

Twisted Tube , internal spiral fins). All are designed to impart a natural swirl component to the flow inside the tubes. Each has been proved to solve the problem of tube-side vaporization at high vapor qualities up to and including complete tube-side vaporization. 

An essential feature of this new design is a better controlled gas flow pattern in the coating zone. This is achieved by application of a guiding system in which the gas flow is accelerated, stabilized, and given a precise amount of swirl, which eliminates slugging, often seen in traditional coaters, and stabilizes multi-tube systems. Particles are... 

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