Study On Performance Of Hydrodynamics And Mass Transfer Of Zigzag Rotating Bed

Rotating Packed Bed or HIGEE, which uses centrifugal force to intensify mass transfer, chemical reaction, micro-mixing and related processes, is a new type of high performance chemical equipment which has brought widely applying prospects in industry.The zigzag rotating bed is a new type of HIGEE, the key part of which is a zigzag rotator. The rotating bed consists of up-rotating disk and down-rotating disk, a number of circular baffle plates are homocentrically installed on the up-rotating disk and down-rotating disk respectively in a certain distance, inlaying the two disks together to form zigzag channels for liquid and gas flowing. The proper residence time of gas and liquid, the uniform distribution of the liquid and the atomization of the liquid in the rotator are the key factors to be able to enhance the mass transfer efficiency of the zigzag rotating bed.The laboratory experiment of the zigzag rotating bed showed that the separation effect of the zigzag rotating bed was better than that of the rotating packed bed when they were compared. The main aim of the paper is to study the separation ability of the zigzag rotating bed at the lager vapor and liquid flux. In the distillation experiment, the pressure drop and mass transfer performance of the single-layer zigzag rotating bed and three-layer zigzag rotating bed were investigated with methanol-water binary mixture at atmosphere and under total reflux condition.The experimental results and conclusions of the single-layer zigzag rotating bed show that:(1) The pressure drop increases with the amount of reflux liquid; andalso increases with the rotating speed;(2) When rotating speed is up to 1600 r/min or more, the masstransfer efficiency has nothing to do with the amount of reflux liquid within the experimental range; at first the efficiency increases with the rotating speed, then decreases a little with the increase of the rotating speed.(3) 5.33 theoretical plates are obtained in the unit with outer diameter520mm, inner diameter 100mm and height 78mm, which is equivalent to 25.38 theoretical plates per meter according to the radial distance that vapor and liquid actually flow through. The experimental results and conclusions of the three-layer zigzag rotating bed show that:(1) The pressure drop of the three-layer zigzag rotating bed is much higher than that of the single one; and the tendency of the pressure drop of the three-layer zigzag rotating bed is the same as that of the single-layer zigzag rotating bed;(2) Liquid flooding point becomes higher with the increase of the rotating speed;(3)The separation ability of the three-layer zigzag rotating bed is much higher than that of the single. The mass transfer efficiency increases with the amount of reflux liquid, and the rotating speed show little effect on the mass transfer efficiency. The equation of the pressure drop was correlated with the Least Square method in the paper. Comparing the estimated values with the experimental values, the errors are within ?0%. According to the flowing conditions of the fluid in rotator, the factors causing the pressure drop due to the frictional and centrifugal forces are analyzed.According to the experimental phenomena, the liquid in the form of films on the baffle plates, flying droplets and flying films moves throughthe zigzag rotating bed, so the mass transfer in the zigzag rotating bed happens not only on the surface of liquid films on the disks and baffle plates but also on the surface of flying droplets and flying films.