Experimental Study And CFD Simulation Of Novel High Efficient Structured Packings

In modern chemical production,the requirements of energy conservation and environmental protection are increasingly strict,so there need new structured packing with excellent performence urgently.In this study,the structure of SP packing was optimized by CFD simulation,and developed NS type packing with higher comprehensive performance,and a new multi-scale CFD model was established to study the hydromechanical properties of NS type wire gauze packing.In this study,the periodic representative unit of the packing with a specific surface area of 700 m2/m3 was selected for CFD simulation.The results showed that the pressure drop per unit height at the turning point of the packing channel increased significantly.When the channel angle was changed to 5mm arc transition,the pressure drop per unit height in the packing channel changes smoothly.In order to study the properties of packings,the hydro-mechanical properties and mass transfer properties of SP packing(700 m2/m3)before and after the structural optimization were studied in the 476 mm diameter plexiglass tower,and compared with CY-700.The results show that in the experimental range,the pressure drop of the new packing is 15.28%lower than that before optimization;when the liquid load L=22.49 m3(m2·h)-1,the wet pressure drop of the new packing is 20.01%lower than that before optimization;the HETP of the new packing is 13.45%lower than that of CY-700 packing.This study first proposed a new multi-scale CFD model suitable for wire gauze structured packing,and studied the effective wetting area and wet pressure drop of the NS type wire gauze packing.An accurate three-dimensional model showing the flow characteristics of the liquid film on the gauze was established on the small scale,and the ratio of the thickness of the liquid film on both sides of the gauze was studied.It was found that due to the porosity of the wire gauze,the liquid flowing through the gauze would have an infiltration effect.The liquid adheres to the gauze and flows forward.The ratio of the thickness of the liquid film on the upper and lower sides of the screen is about 3:5 because of gravity.In the packing cycle unit,the plate is equivalent to the wire gauze by modifying the contact angle and the liquid feeding rate,and the same liquid flow state is obtained on the plate as that on the one side of the wire gauze.The relationship between the effective wetting area of the wire gauze packing and the gas-liquid load is studied.The effective wetting area increases with the increase of the liquid load,but the relationship between the two is not linear,because with the increase of the liquid load,The thickness of liquid film increases correspondingly;when the gas load is small,the effective wetted area is not affected by the gas load.With the increase of gas load,the liquid diffuses laterally under the action of gas drag force,and the effective wetted area increases.Finally,through the combination of pressure drop generation mechanism and CFD,the dry/wet pressure drop is obtained.Comparing the simulated value with the experimental value,it is found that the model has high accuracy.The average deviation of wet tower pressure drop is 8.9%,only when the gas-liquid load is large,the maximum deviation is 24.6%.