| Popis: |
This study has involved the investigation of the flows in a high efficiency cyclone separator and the performance characteristics of the cyclone when operating under the influence of base suction. It has long been accepted that a bleed taken from the base region of a cyclone could, generally, enhance the overall collection efficiency. However, detail analyses and investigations have been limited. This investigation has involved flow visualisation, laser Doppler anemometry, computational fluid Dynamics, as well as both model particle tests and full scale prototype tests to quantify the effect of base suction and cyclone performance. Flow visualisation has highlighted the extension of the vortices into the solid receiver at the base of the cyclone. The flow patterns in this region have been investigated and quantified using laser Doppler anemometry and this result compared to the predictions from computational fluid dynamics. Agreement between these results tends to be good in the inner vortex but less good in the outer vortex region. Model particle tests have shown that the extension of the vortices into the solid receiver results in the complete destruction of the dust layer in the receiver with the subsequent re-entrainment and carry over of particulate to the vortex finder. These particle tests have shown that this re-entrainment can be suppressed by the application of a suction in the base region and the overall collection efficiency improved. A bleed flow of 10% by volume is shown to give the maximum overall efficiency. Above this percentage the efficiency reduces. This trend in the results was also confirmed by full scale prototype tests. |
