Abstract: Experimental study of flow pattern and liquid velocity distribution by the tracer technique in a twometers diameter single pass sieve half-tray using air-water system reveals that there exists a highlynonideal flowing behavior.Typical residence time distribution curves covering the whole tray are presented,from which four flow regions can be observed: a main channelling region of nonuniform flow,a slowly forward flow region in the segmental area,a small region of backward flow and a complete-mixing region next to the inlet weir.The tray models available in literature seem incapable to simulateall these complicated hydrodynamic phenomena in a large tray.An eddy diffusion model with consideration of nonuniform liquid velocity field has been developedfrom the basic partial differential equation of mass transfer by introducing a velocity distributionfunction j.The nonlinear partial differential equation is solved by the method of finite element.Acomputer program is compiled according to this method to compute numerically the concentration pro-files in the whole tray as well as the Murphree tray efficiency enhancement under various operatingconditions.Typical computed results are presented and discussed.

摘要： Experimental study of flow pattern and liquid velocity distribution by the tracer technique in a twometers diameter single pass sieve half-tray using air-water system reveals that there exists a highlynonideal flowing behavior.Typical residence time distribution curves covering the whole tray are presented,from which four flow regions can be observed: a main channelling region of nonuniform flow,a slowly forward flow region in the segmental area,a small region of backward flow and a complete-mixing region next to the inlet weir.The tray models available in literature seem incapable to simulateall these complicated hydrodynamic phenomena in a large tray.An eddy diffusion model with consideration of nonuniform liquid velocity field has been developedfrom the basic partial differential equation of mass transfer by introducing a velocity distributionfunction j.The nonlinear partial differential equation is solved by the method of finite element.Acomputer program is compiled according to this method to compute numerically the concentration pro-files in the whole tray as well as the Murphree tray efficiency enhancement under various operatingconditions.Typical computed results are presented and discussed.