Research On Hydrodynamic Performances Of Fixed Rotary Valve Tray And CFD Simulation

Our group has researched on the novel rotary float valve for a long time,this valve has the characteristics of lower entrainment and weeping,large-range operational flexibility and higher average gas holdups.However,there were still some drawbacks in the actual application processes,for example,the rotary float valve was easier to be worn and get stuck,the flow field was unsteady and optimum performances were limited while the valve in the liquid layer made the partial rotation and the distribution of foam layer height varied.In order to optimize the structure,strengthen rotary flow field and improve efficiency,a novel fixed rotary valve tray was presented in this thesis which made several improvements on traditional rotary valve tray.The hydrodynamic performances of fixed rotary valve trays were experimentally studied with an air-water system in an organic glass column with an inner diameter of 600 mm.The pressure drops,weeping fractions and entrainments of fixed rotary valve trays were measured and compared with those of rotary float valve trays and F1 valve trays.The results showed that the dry pressure drops of fixed rotary valve trays were higher than those of F1 valve trays while the F-factors(kinetic energy factor)get larger.The wet pressure drops of fixed rotary valve trays are lower than those of rotary float valve trays and F1 valve trays.The entrainments of fixed rotary valve trays were obviously lower than those of F1 valve trays by 30%-40% and lower than those of rotary float valve trays by 10%-20%.The capacity performance chart showed that the operation performances of fixed rotary valve trays were much better than those of rotary float valve trays and F1 valve trays.According to the correlation of dry pressure drop and wet pressure drop data,mathematical models of fixed rotary valve trays were obtained,which provided theoretical guidance for industrial production applications.Based on computational fluid dynamics software Fluent 6.3,the gas flow field of fixed rotary valve tray was showed with numerical simulation calculation.For the first time the concept of rotary flow field was proposed.The simulation results showed that realizable k-ε turbulence model was fitted for simulation and analysis of fixed rotary valve trays;wings on the rotary valve had a strong guiding role,which formed the gas phase rotary flow field between valves;it avoided the direct hedge of the gas,reduced the entrainment dramatically,increased the gas residence time in the liquid layer,strengthened the degree of turbulence of the gas-liquid,reduced the dead zone and improved the mass transfer efficiency;the gas velocity at the periphery of the fixed rotary valve was not uniform due to the reasonable arrangement of fixed rotary valve tray,which made the novel tray have a better performance.