The Study Of Mass Transfer Performance For The Cross-type Valve Tray At Partial Reflux

The theoretical researches about the improvements of mass transfer performances, hydrodynamic performances and operational efficiencies by the innovation structure of tray was reviewed.The mass transfer efficiency of the cross-type valve trays was studied in a plate distillation column, with diameter750mm, height4000mm and has four trays, by using cyclohexane and n-heptaneaas experimental system. At atmospheric, weir height50mm and partial reflux conditions, the influence of the kinetic energy factor, reflux ratio and open porosity of valve hole on mass transfer performance were studied. And the experimental results were compared with O’connell model, A.I.Ch.E. model and Kastanek model. According to dimensional analysis, efficiency model for the cross-type valve tray under the condition of partial reflux were established. The results indicated that, at the same operational conditions, the bigger open porosity, the greater tray efficiency volatility, led to the lower efficiency. At the same open porosity, the smaller reflux ratio, meant to the worse mass transfer performance.Kastanek can be directly used in float valve tray and its values were closer to the actual measured dates. The established efficiency model for cross-type valve tray was more accurate. The relative errors were within10%between the experimental data and the value of the established model, and with same trends. The reflux ratio, open porosity and physical properties and the kinetic energy factor were fully considered while building the experimental correlation model. Therefore,the separation efficiency of cyclohexane-n-heptane mixture at the pilot tower, can be predicted accurately. The cross-type valve tray model can serve as an important reference for future industrial production.