Advantages and risks in increasing cyclone separator length

The effect of cyclone length on separation efficiency and pressure drop has been investigated experimentally and theoretically by varying the length of the cylindrical segment of a cylinder-on-cone cyclone. Experimental results based on cyclone lengths from 2.65 to 6.15 cyclone diameters showed a marked improvement in cyclone performance with increasing length up to 5.5 cyclone diameters; beyond this length the separation efficiency was dramatically reduced. Experimental data agreed well with the predictions of a range of models and CFD simulations. This helps to assess the benefit of prolonging a given cyclone. The physical mechanisms behind the observed trends are elucidated. The dramatic fall in separation performance for the longest length was caused by the " natural turning " phenomenon.