Study Of Mass Transfer And Micromixing Performance Of RPB With Combined Hydrophilic And Hydrophobic Wire Mesh Packing

A rotating packed bed(RPB)is an efficient gas-liquid and liquid-liquid mass transfer and mixing device,which has been widely used in separation and reaction process enhancement in chemical industry in recent years.Packing is the core part to shear the gas and liquid phases by centrifugal force in the RPB.The structure and surface properties of packing have obvious influence on the flow behavior of gas-liquid,which affects the mass transfer and mixing performance of the RPB.In this work,hydrophilic and hydrophobic modification of stainless steel wire mesh was carried out.NaOH-CO2 system and parallel competing reaction of the iodate-iodide system were used to investigate the effect of surface wettability of stainless steel wire mesh on mass transfer and micromixing performance in the RPB with the combined hydrophilic and hydrophobic stainless steel wire mesh packings.Based on the liquid dispersion effect on surface-modified wire mesh,a new type of pre-dispersed packing structure was designed.The effective interfacial area(ae)of the RPB with new structure packing was measured.The main results are shown as:(1)The measurement of the effective interfacial area(ae)of a unispecific packing was carried out.The value of the effective interfacial area(ae)of hydrophilic modified wire mesh packing is the largest,while the value of the effective interfacial area(ae)of hydrophobic modified wire mesh picking is the smallest.The spread and shrinkage of liquid film on the fibers recorded by high-speed camera showed that the order of the shrinkage rate of liquid film on fibers is OSM>NSM>ISM.The order of the final length of the liquid film on fibers is ISM>NSM>OSM.Based on some reasonable assumptions,the liquid film and droplet ratios in mass transfer experiments were calculated.The liquid film ratios of the three packings were OSP:0.12,NSP:0.16,ISP:0.20.The value of the segregation index(Xs)of unispecific packing decreases with the increase of rotational speed and liquid volume,and The value of the segregation index increases with the increase of Hydrogen ion concentration.The micromixing performance of hydrophobic modified weir mesh packing is the best among the three packings,while the micromixing performance of hydrophilic modified weir mesh packing is the worst among the three packing.(2)Two groups of combined packings were designed:The first group is is composed of wire meshes with different wettability in the inner layer of the packing;the second group is composed of wire meshes with different wettability in the middle layer of the packing.In RPB with the two groups of combined packing,the mass transfer performance of the packing with hydrophobic weir mesh is lower than that of the ordinary unmodified weir mesh packing,while the mass transfer performance of the packing with hydrophilic weir mesh is 2%?8%higher than that of the unmodified weir mesh packing.the combined packing with hydrophobic wire mesh exhibit better micro-mixing performance,while the combined packing with hydrophilic wire mesh exhibit relatively weak micro-mixing performance.(3)Based on the above results,a new type of pre-dispersed packing was developed.The results of visualization experiments on RPB with single-layer wire mesh show that the rotating single-layer OSM can cut the liquid column into smaller droplets and make it have larger dispersion cone angle compared with single-layer NSM.The effective interfacial area(ae)of the packing with a single layer hydrophobic wire mesh is better than that of the packing with a single layer hydrophilic wire mesh,and both of them are better than that of the packing with a single layer unmodified wire mesh.