Study On Performance Of Zigzag Rotating Bed

A rotating packed bed (also called Higee or RPB) using centrifugal force to intensify mass transfer and chemical reaction, is a new type of high-performance equipment which was developed in the early eighties. It has wide application and bright prospect in industries, such as absorption, stripping, distillation, extraction and other separation processes. Some researches on performance of hydrodynamics, mass transfer and power consumption of the rotating bed have been studied, but mainly on absorption and stripping unit operation in the PRB, few researches on distillation.The zigzag rotating bed is a type of the latest developed Higee ,the key part is zigzag rotator. The rotator consists of immobile disk and rotational disk. A number of circular baffle plates are homocentrically installed on the immobile disk and rotational disk respectively at certain distance, inlaying the two disks together to form zigzag channels for liquid and gas flowing. Gas-liquid mass transfer intensification is primarily based on the results of great effective mass transfer area generated in liquid constant atomization, the proper residence time of gas and liquid, and the uniform distribution of the liquid.The laboratory experiments of the zigzag rotating bed showed thatthe separation effect of the unit was better, it is hopeful that the zigzag rotating bed is applied to distillation. In this thesis , the gas pressure drop and power consumption characteristics of the single-layer mesh and shutter types zigzag rotating bed were studied through the cold model (air /water system) test, and the mass transfer performance of the two structure two-layer zigzag rotating bed were investigated through the hot model (real system) test, under the operation conditions which was suitable for industry applying. The experimental results show that:(1) The pressure drop of the dry zigzag rotating bed is higher than that of wet one. The pressure drop increases when the gas flow rate and rotating speed enhanced, however the pressure drop initially decreases rapidly then keeps constantly almost when liquid introduced to the rotor.(2) The electric power consumption increases slowly as gas flow rate enhanced, however under low liquid flow rate condition, there is a process that the electric power consumption initially decreases slightly, then increases again with the gas flow rate enhanced, both liquid flow rate and rotating speed are sensitive factor of the electric power consumption.(3) The mass transfer efficiency of the two-layer mesh and shutter type zigzag rotating bed decrease with liquid flow rate, and increase with rotating speed then vary a little under total reflux and the same operation conditions. But liquid flow rate largely influences the mass transfer efficiency of shutter type.(4) 9 to 10 theoretical trays can be obtained when the reflux is over 200L/h and rotating speed is 1000r/min in the mesh type zigzag rotating bed.(5) The empirical correlation equation of the pressure drop and the electric power consumption of the two types zigzag rotating bed was derived by regression concerning on gas flow rate, liquid flow rate and rotating speed. The results of regression are agree well with those of experiment about a relative error of 10%.(6) The characteristics of the mesh type zigzag rotating bed are better than those of shutter type. So the mesh type is suitable, and the optimum rotating speed is about 1000r/min in industries.