A Case Study the Effect of Cyclone Length

The effects on performance of some cyclone dimensions, such as gas inlet and outlet dimensions, have been extensively studied. An effect that is less well researched, and less well imderstood, is that of cyclone body length. We can therefore see it as a decisive test for the quality of the performance models, namely, whether they can predict this effect correctly, at least up to the point at which we reach the natural turning length . 

Having discussed the flow in cyclones, and the principles behind some models, we are able to anticipate to an extent the effects of increasing cyclone 

In a recent study (Hoffmann, Groot, Peng, Dries and Kater, 2001) the effect of increasing the cyclone body length considerably on the performance was tested. The cyclone had dimensions D= 0.200 m, = 0.065 m, Dd = 0.110 m, S= 0.140 m, a= 0.114 m, b= 0.050 m and He = 0.410 m. It was equipped with extra cylindrical sections so that the length of the body could be varied between 0.260 m and 0.960 m. The cyclone feed was a chalk powder with density 2730 kg/m dispersed in ambient air entering with an inlet velocity of 19 m/s. The dust loading was low at approximately 1.6 or 

7 g dust/m gas. The range of cyclone lengths and the effect on separation efficiency and pressure drop are shown in Fig. 5.3.2. 

The cut size X50 is seen to decrease slightly with increasing cyclone length, although the last result is atypical (and we will return to this issue below). The pressure drop decreases with increasing cyclone length as we anticipated. 

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