370368 Improving Separation Efficiency of Cyclone By Adding Large Particles

Monday, November 17, 2014: 10:43 AM
210 (Hilton Atlanta)
Zhihong Liu, Research Laboratory, IHI Corporation, Yokohama , Japan and Dirk Riechelmann, Heat & Fluid Dynamics Department, Research Laboratory, IHI Corporation, Yokohama, Japan

A new technique of increasing the separation efficiency of cyclones is proposed. The technique is investigated numerically, and its superior performance is shown.

 The effect of particle load and particle size distribution(PSD) on the grade particle separation efficiency is studied. The numerical results show that the particle loading of a class of particle diameters is a better parameter than PSD to describe the effect of particle concentration on the change of separation efficiency. The load of large particles on the separation efficiency has a different effect than that of small particles. It is shown that the separation efficiency decreases, when the load of small particle increases, because small particles weaken the tangential velocity of particles in the cyclone. On the other hand, the separation efficiency increases, when the load of large particles is increased, because the wake generated by the large particle entrain small particles and pull them down, being separated from the gas.

 The above mechanism is employed to improve the separation efficiency of cyclones. Large particles, which are large enough that they are separated completely, are injected from the top ceiling of the cyclone, to cause downward wakes, which then invoke small particles move downwards and thereby increase separation efficiency.

The numerical studies reveal that there exist an optimal load of large particles to achieve best separation. When the load of large particles is increased from zero, first, separation efficiency increases, because of augmenting wake effect. However, when the load of large particle exceeds a certain load, namely the optimal load, separation efficiency decreases, because the high concentration of large particles weakens the tangential particle velocity.

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