Experimental study on the effect of connecting ducts on demisting cyclone efficiency

The purpose of this study was to improve demisting efficiency by optimizing geometry of connecting ducts between droplet generation source and cyclone separator. Since the separation of fine droplets is typically difficult for the cyclone, increasing the size of the droplets increases the separation efficiency. Further effect of the shapes of the vertical duct as a part of connecting assembly to the cyclone separator was studied. Circular, triangular and rectangular cross sections ducts with a hydraulic diameter of 14 mm were examined. The droplet deposition rate in connecting duct and the cyclone efficiency for different duct geometry were measured for different flow rates. The laser light scattering technique was used for measuring the droplets size. Moreover, the vapor/droplets and droplets efficiency of the cyclone was measured using the weighing method and droplets efficiency was compared with the theoretical model. To measure the cyclone droplet capture efficiency, a high efficiency glass micro fiber was used. The results indicated that the theoretical model prediction and the weighing method are in good agreement for droplet capture efficiency of the cyclone especially for high flow rates. It was also found that the volume fraction of droplets larger than 2 μm at the outlet of the triangular and rectangular ducts were higher than the circular ducts. The highest droplets/vapor cyclone efficiency was recorded for the rectangular and triangular ducts comparing to the circular ducts at the same hydraulic diameter.

► The effect of geometry on the outlet drops size of the vertical ducts using laser diffraction method is investigated.
► The efficiency of a demisting cyclone and deposition in channel using weighing method is measured.
► The duct geometry before the demisting cyclone can affect the cyclone efficiency.
► Rectangular and Triangular ducts can increase the demisting cyclone efficiency comparing to circular ducts (nearly 10%).