| The Combined Gas Distributor is made up of the Twin-Tangential Annular Flow Gas Distributor and the Two-Line Vane Gas Distributor. It's an important gas distribution device services for large-scale towers with large-diameter inlet. Its performance is directly related to separation efficiency and final qualities of productions. In this paper, both methods of experiment and Computational Fluid Dynamics (CFD) are utilized to study the performance of the combined gas distributor in a 6200mm-diameter column with a 3000mm-diameter inlet. As a result, many detailed systemic data and pictures are obtained to describe the gas flow that passed through the combined distributor. The result is available for structural optimization of large inlet gas distributors.The uniformity of the gas flow through the packing is assessed by means of a mal-distribution factor, Mf. Together with the other indicators, such as pressure, pressure drop, velocity, turbulent kinetic energy, turbulent dissipation rate, the performance of the combined gas distributor can be over-all-merited. The influence of the quantity of vanes and baffles, width of the annular plate and split radio on the performance of the gas distributor are researched and the followed results are obtained. There are no obvious changes for pressure drop and mal-distribution factor when the quantity of vanes and baffles increase. With the widening of the annular plate, pressure drop increases, while mal-distribution factor goes up and then down. The increasing split radio causes a decreasing pressure drop and an inverse mal-distribution factor change compared with the widening of the annular plate. When the width of annular plate is 500mm and split radio is 4, the performance of the gas distributor reaches the best.Additional attempts were also made to improve the basic structure of Combined Gas Distributor. The results show that the performance will be better when the annular plate is moved down or open holes on it even wipe it off completely. The performance will deteriorate when holes are opened on rearward inner cylinder or additional inner baffles are added. The other improvements such as moving down the cover board, opening holes on it or the front inner cylinder were found without effect on the performance. In addition, flow field of air lift distributor was measured in order to test the reliability and veracity of model and software. The comparison between experiment results and simulation results reveals a sound correspondence between the tested and the simulated, as well as the feasibility for the results to direct an engineering design. .
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