Aiming at improving collection efficiency in the cyclone separator, the effects of inlet height and velocity on tangential velocity, static pressure and collection efficiency were studied. A three-dimensional model including gas-flow, and particle-dynamics fields was built by the Reynolds stress turbulence model, and the numerical simulation was achieved using the FLUENT software. The static pressure distribution, tangential velocity distribution, and particle trajectory of the cyclone were obtained, and the variation law of the collection efficiency with inlet height and velocity as well as particle diameter was analyzed. Numerical results indicate that both the static pressure and the tangential velocity in the cyclone basically present the axial symmetrical distribution, the static pressure shows a nonlinear increasing trend in the radius direction and the distribution of the tangential velocity is in the shape of a “hump.” The increase of inlet height in a certain range reduces the rotation numbers of particles in the cyclone and shortens the residence time, which results in the improvement of trapping performance. Furthermore, the appropriately increasing inlet velocity in a reasonable range can make the collection efficiency increased.

Eliminating fine particles from flue gas is of vital importance to improve air quality, so an outer vortex type electrocyclone (EC) designed with corona wires was built and used to trap submicron particles. Besides, a mathematical model under multi-field coupling effect was established and the charging effect rule on collection efficiency of submicron particles was revealed by comparing the performance of electrocyclone with cyclone and changing operating conditions. The results indicate that the application of charging effect greatly reduces the escape of submicron particles, making that the collection efficiency in EC is far higher than the one in cyclone. Compared to the cyclone, the ability of charging effect to promote the separation performance of EC increases with the increasing working voltage and the decreasing flue gas velocity and temperature and the trapping performance is better at a higher working voltage, lower flue gas velocity, and lower temperature. Furthermore, for outer vortex type EC, the charging effect is more prominent with the decrease of working voltage, flue gas velocity and temperature. The obtained results were evaluated to provide a reliable guide for designing an outer vortex type EC, thus greatly decreasing the number of tests and effectively reducing the research cost.