Heterogeneous condensation combined with inner vortex broken cyclone to achieve high collection efficiency of fine particles and low energy consumption

Abstract

Gas cyclones are widely used for separating particles from gas, while recently various techniques have been developed to improve their performance. One is to use the supersaturated water vapor to increase the sizes of fine particles and hence their collection efficiency and another is to use the vortex-broken wing to decrease the pressure drop. This paper studies the synergistic effect of these two techniques. The supersaturated vapor, the vortex-broken wing and their combination were added to a conventional cyclone respectively and compared to the original cyclone by both experiments and numerical simulations. Through experiments, it was found that the removal efficiency of fine particles in the cyclone with the combined techniques was improved significantly while the pressure drop was reduced at the same time. The mechanism for such improvement was revealed through the computational fluid dynamics simulations. It was observed that the inner vortex can be effectively destroyed by the vortex-broken wing. This not only reduced the pressure drop, but also decreased the turbulence intensity under the vortex finder, which promoted the diffusion of water vapor and made the vapor distributes more uniformly. As demonstrated in the simulation, the improvement of the vapor distribution can enlarge the supersaturated region and enhance the condensational growth of fine particles. This was also testified by the online laser particle size analyzer in experiments. The findings establish a theoretical guidance for this new type cyclone and may provide new idea for the treatment of fine particles.