Swirl tube

Bring samples to room temperature. Vortex or swirl tubes to rinse the condensate from the tube walls. 

These trays include the Ultrfrac , the ConSep (Fig. 14-26 ), and the Swirl Tube trays. This technology has been sporadically used in eastern Europe for quite some time. It is just beginning to make inroads into distillation in the rest of the world, and looks very promising. 

The stripped catalyst gravitates through a short standpipe into a single vessel, simple, reliable and yet efficient catalyst regenerator. Regenerative flue gas passes via a cyclone/swirl tube combination to a power recovery turbine. From the expander turbine the heat in the flue gas is further recovered in a waste heat boiler. 

This potential can be expanded significantly by the use of an installation (Fig. 3.37) for the application of pol3mier powder compositions [66]. The gas-polymer powder mixture is fed from the source into helix 2 of the vortical tube and is transported in a spiral stream 3 to socket 4. Inhibitor-1 is supplied from source 5 to a gap between socket 4 and cylindrical female mouthpiece 6 fixed on helix 2 face of the vortical tube and moves in the gap in a spiral stream 7. lnhibitor-2 fed from source 8 is sprayed in flow 9 through nozzle 10 installed along the swirl tube axis. 

Figure 7 Third stage separator, blow-up of swirl tube, emissions improvements.

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.)... 

To improve the cooling process and droplet stream deflection, a swirl tube (Fig. 10.3) was installed on top of the spray-freeze tower. Gaseous nitrogen was... 

Fig. 10.3 Schematic cross sections of swirl tube (left), with pipe inserts centre) and the redesigned jet-vortex-freezer right). The grey area indicates the range of DSG positions inside...

With the present configuration, the frozen droplets are not yet uniform, but further improvements can be achieved by systematic evolutionary optimization of the process parameter settings. The small diameter of the current swirl tube sets an upper limit to the velocity of the gas flow beyond a threshold, the yield decreases because incompletely frozen particles impinge upon the walls and form crusts. Trying to solve this problem merely by experimentation would not be economical, this is the domain of computational fluid dynamics. 

To reduce the particle size of the spherolyophilisates, a swirl tube was developed, in which a jet of pre-cooled gaseous nitrogen was directed orthogonally at the droplet... 

The fourth type of inlet we wish to describe is that of swirl vanes. As shown in Fig. 1.3.8 d, a swirl-vane assembly allows the gas to enter the cyclone parallel to the axis of the cyclone The swirl-vane assembly is positioned between the vortex finder (or, in case of a straight-through device, see below, a central solid body) and the outer (body) wall of the cyclone. This type of inlet is often inserted in cylindrical-bodied cyclones rather than in cylinder-on-cone or conical-bodied geometries. When it is, we refer to the separator as a swirl tube. Swirl tubes are often of small size (by commercial standards) and are most commonly arranged in a parallel array on a common tube-sheet within a pressure-retaining vessel. They are normally fed from, and discharge into, common, but separate overflow and underflow plenums. 

This section discusses some aspects of fluid mechanics that are particularly relevant to cyclones and swirl tubes. 

The flow and pressm-e distribution within cyclones and swirl tubes is more easily understood if we make clear the relation between static and dynamic... 

The left-hand side of Eq. (2.1.3) is sometimes called Bernoulli s trinomial . The second term is unimportant relative to the two others when discussing gas cyclones and swirl tubes, since the fluid density is relatively low, and height differences not very large. 

In a gas cyclone or swirl tube, the particles of interest are almost always moving relative to the gas at their terminal velocity, and the terminal velocity of a given particle determines whether it will be captured or lost. This terminal velocity is exactly analogous to that of a particle settling in the earth s gravitational field, g, under steady-state conditions except that, for a cyclone, the radially directed centrifugal force, mvg/r replaces the gravitational one. This will be discussed in detail later. 

Fig. 3.1.1. Sketch of a tangential-inlet cyclone with the flow pattern indicated. The coordinate directions are shown, normally the 2-axis coincides with the axis of the cyclone or swirl tube. To the right, the radial distributions of the axial and tangential gas velocity components are sketched. It is understood that the dust outlet may be the Uquid outlet for the case of a demisting cyclone...

The losses in the entry are often negligible compared to the other contributions, at least in tangential entry cyclones. For swirl tubes with inlet vanes little information is available, but if the vanes are properly contoured aerodynamically, the losses are generally small. 

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. 

This completes om short discussion of flow pattern and pressure drop. We now tmn to the models. By far most of the modeling work has concentrated on cyhnder-on-cone cyclones with tangential inlets. We will therefore talk of cyclones in these sections. Very little direct work on the modeling of the flow pattern and the pressure drop in swirl tubes has been published our... 

Figure 4.5 shows results of both experiment and CFD in a swirl tube with a cylindrical body (Peng et ah, 2002). In the left-hand figure a series of measurements are shown where the boundary between the up- and downwardly directed flow has been determined using laser-Doppler anemometry (LDA, we... 

Fig. 4.4.1. LDA measurements and CFD simulations in a swirl tube with different vortex finder diameters. In a the boundary between the up- and downwardly directed flow have been pinpointed with LDA. In b the loci of zero axial velocity have been made visible in a CFD flow field by plotting contour plots of which shows...

In much of the cyclone literature the radial position of the boundary between up- and downward flow is held to determine the cut size of the cyclone or swirl tube. However, for a particle caught in the upward flow to be lost, it... 

Another assumption made in the models is that the swirl velocity profile (its radial distribution) in the cyclone is constant axially. Figure 4.4.2 shows LDA measurements of the radial profiles of the tangential velocity at a series of axial stations in a cylinder-on-cone cyclone with a conventional slot-type inlet. Figure 4.4.3 shows a similar plot for a swirl tube with a cylindrical body. 

The figures show that the profile of the dimensionless tangential velocity is constant at all axial positions in the cylinder-on-cone cyclone, even until deep in the conical section. In the swirl tube there is a slight tendency for the tangential velocity to decrease as we move down. Overall, the measurements confirm the validity of this model assumption at least for geometries most commonly found in commercial service. 

A third assumption made in cyclone performance models is that the radial velocity is uniform over CS. The radial velocity is the smallest velocity component, and it is more difficult to measure with LDA than the other components. We can again resort to CFD to get an impression of the flow pattern. Figure 4.4.4 shows profile plots of the radial velocity distribution in both a cylindrical swirl tube and a cylinder-on-cone cyclone with slot inlet. 

Fig. 4.4.3. The tangential gas velocity measured with LDA at a series of axial stations in a cyhndrical swirl tube. The highest station is just under the vortex finder. The darker the points the lower the station...

Fig. 4.4.4. Profile plots from CFD simulations of the radial velocity distribution in a cylindrical swirl tube and a cylinder-on-cone cyclone. The main difference between the two is that the radial flow from the outer to the inner vortex is more uniformly distributed axially in the cyclone than in the swirl tube...

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. 

Barth Cyclones and swirl tubes Considers the frictional losses in the body. The effects of wall roughness and solids loading are accounted for in the value of the friction factor, /. 

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