Experimental investigation on separation performance of cyclone separators for non-spherical particles

Key words:  non-spherical particle  cyclone separator  separation efficiency  pressure drop

Abstract:

A comparative experiment was conducted to investigate the cyclone performance for non-spherical particles. The silica powder (non-spherical) and coal fines (spherical) were selected as the test media. The silica powder particles are slightly bigger and heavier than the coal fines. The results show that the separation efficiencies for both particles rise firstly and then drop with the increase of inlet velocity, while their pressure drops increase continuously. Moreover, the efficiencies for both particles decrease with the increase of gas temperature. However, the separation efficiency of silica powder is unexpectedly lower than that of coal fines, and the pressure drop is also less. The reasons lie in the difference of particle drag force and friction between the cyclone wall and the so-called ‘dust layer’ formed by near-wall particles. For the silica powder, the friction between its dust layer and cyclone wall becomes greater because the dust layer moves more difficultly on the cyclone wall. Therefore, the gas rotation is hindered more greatly, the centrifugal force field becomes weaker and the separation efficiency becomes lower. Besides, the drag force on a non-spherical particle is usually larger, which further undermines its separation. As for the pressure drop, although a greater friction on the wall will lead to a higher pressure drop, a weaker swirl flow caused by the greater friction means a much less dissipation loss of gas dynamic energy in the outlet pipe. The overall effect is that the pressure drop for silica powder becomes lower than for coal fines.