Tangential inlet cyclone

Fig. 29-6. (a) Tangential inlet cyclone, (b) Axial inlet cyclone. 

For the engineering design of tangential inlet cyclones, the variation of the tangential velocity in the radial direction can be correlated in a form... 

For most tangential inlet cyclones, varies from 0.5 to 0.7. 

Figure 7.8. Geometric configuration of the tangential inlet cyclone.

It is noted that the particle-wall interaction in the boundary layer and the electrostatic effect due to the electrostatic charge carried by the particles may strongly affect particle collection and reentrainment in the cyclone and, consequently, affect the collection efficiency. In the presence of electrostatic charges of particles and an external electric field, the collection efficiency of a tangential inlet cyclone with a steep cone is given by [Soo, 1989]... 

In the presence of electrostatic charges of particles and an external electric field, the cut-off size of a tangential inlet cyclone with a steep cone is given from Eq. (7.30) as... 

Over the decades that cyclones have been used, many different reverse-flow cyclone geometries have been tried to improve efficiency, prevent particle attrition, prevent erosion of the cyclone wall, or prevent particle buildup on the cyclone surfaces. However, there are a few basic types that have emerged as the most popular over the years. Some of these cyclone types are shown in Fig. 3. The cyclones shown in this figure are the tangential inlet cyclone, the volute Met cyclone, and the axial inlet cyclone. This last type of cyclone uses axial swirl vanes to impel the gas solids mixture into rotary centrifugal motion. 

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...

Fig. 7.1.4. Profile plots for the tangential velocity in a tangential inlet cyclone, with the area of low near-wall velocity on the back of the vortex finder indicated...

Cyclone designers have long known that the separation efficiency of tangential inlet cyclones improves with increasing solids loading. Even so, the exact mechanism for this improvement is still not established beyond doubt, in spite of many investigations of the topic. 

Much less experimental data are available on the effect of solids loading on the separation efficiency of swirl tubes with swirl vanes. If the effect of solids loading is indeed one taking place in the inlet region of tangential inlet cyclones, we might expect it to be quite different in devices with swirl vanes. 

Figure 9.2.5 shows the wall pressme profile along the entire length of a tangential-inlet cyclone. The remarkable thing about this data is the very sharp decrease in static pressure that occm in the vicinity of the plane where the end of the vortex attaches to, and processes around, the walls of the hopper. This sharp dip in static pressme is, of course, a direct result of the low-pressure vortex core contacting the hopper wall. 

In conventional tangential inlet cyclones the swirl velocity near the wall is determined by the entrance duct velocity Cj , and an entrance constriction coefficient. In swirl tubes, it is mostly determined by the velocity exiting the... 

The simplest type of centrifugal device is the cyclone separator (Fig. 3.4), which consists of a vertical cylinder with a conical bottom. The centrifugal force is generated by the fluid motion. The mixture enters in a tangential inlet near the top, and the rotating motion so created develops centrifugal force which throws the particles radially toward the wall. 

Fig. 8. Cyclone types commonly used (161) (a) conventional, large diameter, tangential inlet, axial discharge (b) smaller tube, tangential inlet, peripheral concentrated aerosol discharge (c) small tube axial inlet and discharge (d) smaller tube axial inlet, peripheral concentrated aerosol discharge.

The most common inertial collector is the cyclone, which is used in two basic forms, the tangential inlet and the axial inlet. Figure 29-6 shows the two types. 

In actual industrial practice, the tangential inlet type is usually a large (1-5 m in diameter) single cyclone, while the axial inlet cyclone is relatively... 

For the typical cyclone of Figure 4-41 with tangential inlet ... 

The inner vortex (often called the core of the vortex) rotates at a much higher velocity than the outer vortex. In the absence of solids, the radius of this inner vortex has been measured to be 0.4 to 0.8 r. With axial inlet cyclones, the inner core vortex is aligned with the axis of the gas outlet tube. With tangential or volute cyclone inlets, however, the vortex is not exactly aligned with the axis. The non-symmetric entry of the tangential or volute inlet causes the axis of the vortex to be slightly eccentric from the axis of the cyclone. This means that the bottom of the vortex is displaced some distance from the axis and can "pluck off and reentrain dust from the solids... 

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. 

Figure 1.113 Cyclone mixer design with tangential inlets only.

Figure 38 (Liu et al., 1990b) shows a four-inlet cyclone. Solids tend to be densified around the inlet region as the vertically entering solids-laden streams are suddenly diverted toward tangential flow in a horizontal plane. At inlet velocities exceeding 8.5 m/s, the overall separation efficiency for a typical FCC catalyst was found to be consistently above 99%, as shown in Fig. 39. This design, however, resulted in relatively high pressure drop unless the inlets were appropriately enlarged. The efficiency and pressure drop of this type of multi-inlet cyclones could be approximated by modifying the single-inlet cyclone expressions (Kou, 1987 Shi et al., 1987) ...

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