Separation Performance And Internal Surface Modification Of Wave-plate Mist Eliminator With Different Drainage Structure

Wave-plate mist eliminators have advantage of simple construction,low pressure drop,high process capability,and low cost of manufacturing and maintenance.They are widely used in the fields of natural gas purification,wind power generation,and nuclear power generation.The drainage structures have important influence on separation performance and internal gas-liquid two phase flow of wave-plate mist eliminator.An experimental set-up is established for researching the separation mechanism of drainage structures.The influence of drainage structures and operating parameters on the separation performance of the mist eliminator is studied by experimental measurement and numerical simulation.The wave-plate surface is modified by biological principle to optimize the drainage performance of mist eliminator.The research results are intended to provide theoretical support for the advanced design and operation optimization of industrial mist eliminators.The performance parameters of wave-plate mist eliminators with and without drainage structure are measured by the separation performance evaluation device.The influence of liquid concentration,droplet size distribution and operating pressure is analyzed.The results show that the drainage structure can be used to improve the ability of wave-plate mist eliminators to separate small size droplets and inhibit the occurrence of re-entrainment.The separation efficiency and pressure drop of wave-plate mist eliminator are increased by drainage structures,especially when the air handling capacity varies widely.When the operating parameters change,the effect of drainage structures is more obvious.The performance of a typical new type wave-plate is evaluated,and the reason why the performance of it is better than that of conventional wave-plates is analyzed based on simulation results.It is found that the pressure drop of mist eliminator is low and the efficiency of it can be maintained stable at high air speed.The reason is that non-uniform structure consisting of drainage hooks and drainage pockets has smaller disturbance to flow field of wave-plate mist eliminator,and the inhibitory effect of drainage pockets on re-entrainment is stronger than that of drainage hooks.The performance prediction model of wave-plate mist eliminator is established by Response Surface Method(RSM),which can be used to optimize the structural design of new wave-plates.Some problems of drainage structures of wave-plate mist eliminator have been proposed.For example,the pressure drop of drainage structures is too high,and solid particles in the airflow may lead to the blockage failure and damage of the drainage structure.A method for hydrophobic modification of wave-plate surface by using biological principle is presented,and it improves the separation performance of mist eliminator by enhancing the drainage performance of mist eliminator.Based on flow characteristics of liquid on solid surfaces,surface hydrophobicity and droplet morphology of different microstructures are analyzed.The separation performance of the modified surface is compared with the unmodified surface.The results show that the drainage performance of mist eliminator is improved obviously,and the effect of re-entrainment is reduced.The pressure drop of the surface modified wave-plate mist eliminator is much lower than that of the traditional wave-plate mist eliminator with drainage structures.The method of microstructure surface modification for mist eliminator is effective.The hydrophobic properties of different micro-column units on microstructure surfaces and the influence of dimension parameters of micro-column unit on performance of wave-plate mist eliminator are discussed.A prediction model for the separation performance of microstructure wave-plate mist eliminator is proposed,which shows good agreement with the experimental results.