Experimental and numerical evaluation of the performance of a novel compound demister

Abstract

A novel compound demister that combines an upstream tube bank and downstream wave plates was proposed in this work for application in multistage flash (MSF) desalination process. Its performance was evaluated by experimental and numerical methods. Compared with the individual tube-bank and wave-plate demisters, the compound demister is found to have the highest separation efficiency (> 95%) with much less fluctuation for a wide range of gas velocities. At low gas velocities (≤ 4 m/s) or for removing small droplets (< 20 μm), the separation efficiency of the compound demister is much higher than that of the wave-plate demister mainly because of the large separation capability of the tube bank. At high gas velocities (> 4 m/s), the compound demister shows higher resistance to droplet re-entrainment that occurs at inlet gas velocity of approximately 7 m/s compared with the tube-bank demister. This is due to the compensation from the wave plates in the compound demister that separate secondary droplets generated by tubes. The compound demister possesses higher dry pressure drops than either the tube-bank or wave-plate demister, but is acceptable for industrial application. All these advantages make the compound demister a promising candidate for droplet removal in the desalination process.