Study On Gas Flow And Mass Transfer Of Structured Packing

In recent years, study on the structured packing developed slowly, because it was difficult to investigate local mass transfer on the surface of the structured packing without disturbing the flow field. Therefore, Emperical/Semi-emperical models are still dominant in determining hydrodynamic and mass transfer parameters although where exist errors around 15%-20% compared with the real situation. In order to improve this situation, local mass transfer on the surface of structured packing is employed to take the place of traditional average mass transfer.A chromochemical reactive mass transfer technique has been employed to calculate values of local mass transfer coefficients within structured packings. The true-color image processing method with the tool of high-resolution scanner is firstly used to deal with test samples. With the aid of wind tunnel, the calibration curve which represents the relationship between local mass transfer rate and the color intensity is made. Then, local mass transfer coefficients are got. The local mass transfer in the surface of structured packing is studied under different Re. The experiments'results clearly show that the mass transfer distribution in the surface is asymmetrical and three peaks on different positions exist in a unit cell of the corrugated structured packing.One piece of block is added between two pieces of structured packing since the asymmetrical mass transfer on the surface. After adding the block, mass transfer on the surface of structured packing is improved and pressure drop between inlet and outlet is largely decreased. However, block will reduce the opportunity that liquid phase wet the surface leading to reduce the mass transfer area between gas and liquid phase. Therefore, some rhombic holes are made on the block to reduce the harmful effect, and the vertex direction of these holes is parallel with flow direction. In the paper, the relationship between average mass transfer coefficient and percentage of area of these holes, only considering the gas effect, is provided for the further research on this field.Gas flow in the middle of two pieces of structured packings is simulated with the FloWizard, one kind of computational fluid dynamics tools. And, the real reasons of the asymmetrical mass transfer in the middle part are found out by simulating microcosmic part of structured packing. Finally, the mass transfer on the surface is simulated with Fluent, another kind of computational fluid dynamics tools. Compared with the results of experiments and calculation, the correctness of CFD is verified by experiments. All of these jobs have provided a new and convenient method for studying other packings and exploring new kinds of packings.