Study On The Hydrodynamics Of The Outlet Of Downcomer

Distillation column is a very important equipment in the chemical industry, itcontains two styles: plate column and packing column. In recent years, the research onplate column has made much progress, the fluid field in distillation tray is one of themain aspect, but the hydrodynamics of the outlet of downcomer is an important factorfor research on tray.The hydrodynamics of the outlet of two different downcomers was studied withFLUENT(a CFD software),one is traditional arc downcomer, the other is leandowncomer.The profile of fluid velocity along different axis at the outlet and the conditionof mixture at the bottom of downcomer were obtained from the research. For thetraditional arc downcomer, the profile of velocity along X axis has three regions, it islarger at the center, but along Y axis, it is smaller at the center. There are somedifferences between the lean downcomer and the arc downcomer, the profile ofvelocity along X axis has four regions, along Y axis, when the flux is small, it isalmost uniform near the center, just at the sides, there are some waves. When the fluxis large, the uniform region is disappeared. The fluid is partly mixed in the twodowncomers, the condition of mixture is more sufficient in the lean downcomer, it isreasonable that assuming the concentration is uniform when computing trayefficiency.The profile of velocity at the inlet of tray can be gained through the research.Near the center, the velocity is uniform, but disordered at the sides.The simulating results were compared with the experiment;it is showed that thesimulating results are credible.