Study Of Hydrodynamics Measurement And Mass Transfer Performance On Fine Bubble Tray

Tower equipment widely used in oil refining and chemical industry is an important gas-liquid and liquid-liquid mass transfer equipment for separation. The disadvantage of complex structure and high production cost exist in the development of both packed tower and plate tower in distillation. So researchers look for methods, which can not only increase tray efficiency but also maintain simple structure. In trace separation process, the bubble diameter plays a key role in the level of tray efficiency. Smashing large bubbles is an effective way to increase the separation efficiency, which can also strengthen the surface renewal and enlarge gas-liquid inter facial area. Adding a layer of mesh is the most effective way to smash large bubbles. The structure is studied by simulation and experiment.In this paper,3D-unsteady gas-liquid flowing on trays is established by Euler-Euler model. The best structure is concluded by gas hold-up and opening percent. The installation height of the square mesh is 25mm and opening percent is 55.7%. The single-mesh is more suitable for industrial application. The distribution of the large and small bubbles in the tower are concluded by CFD-PBM model simulation. The average bubble diameter of the micro-bubble tray is only 12% of the sieve tray. By the comparison of the two results, mesh can make the gas phase distribution become more uniform, eliminate the large vortex and adjust the gas flow direction. These changes benefit for mass transfer efficiency.To analyze the various parameters, the paper use air-water system to do experiment of sieve and the micro-bubble tray, and a series of studies of bubble characteristics are carried out. The results show that, the best installation height of the mesh is 25mm and the best aperture is 5 orders to the micro-bubble tray. The average wet tray pressure drop of the micro-bubble tray is 0.243kPa,44% higher than sieve tray, which cause large energy consumption. The average bubble diameter of the micro-bubble tray is 5.16mm, only 15% of the sieve tray which match the simulated results. The average gas hold-up of micro-bubble tray is 3.28% higher than sieve tray. Pressure fluctuation in micro-bubble tray is relatively stable and the power spectral density figure also reflects the small bubbles can maintain their shape better. Breakage frequency is far below the sieve tray and has a great improvement to the operation state of the tower.In this paper, SO2 desorption experiment is selected to analyze the mass transfer efficiency. The results show that:for ordinary desorption, the desorption efficiency of the micro-bubble tray is 86.85%, which is 1.87 times of the sieve tray under the same condition. The desorption efficiency of the micro-bubble tray is more than 50% under trace desorption, far greater than the desorption efficiency of sieve tray. The SO2 content can be reduced to less than 20mg·L-1, which is much lower than the sieve tray.Therefore, in the process of trace separetion, the micro-bubble tray has good application prospects.