Numerical Study And Optimization For The Separation Performance Of Guide Vane-Type Demister

Demister is a necessary part of the wet flue gas desulfurization system whose separation performance has an important impact on the stable operation of downstream equipments.Because of its relatively simple structure,high demisting efficiency and advantage in separation of small droplet,guide vane-type demister has been paid more and more attention.In this paper,the separation performance of guide vane-type demister is studied by using computational fluid dynamics software Ansys Fluent.In particular,the effects of six process parameters on the demisting efficiency and pressure drop of demister are studied.The process parameters include vane numbers,vane angles,inner cylinder diameters,ring gap widths,cyclone part heights and inlet velocities.The orthogonal design method is used to optimize the process parameters of guide vane-type demister and a set of optimal process parameter combinations is obtained.At the same time,the primary and secondary order of effects of various parameters on the pressure drop and the demisting efficiency are obtained.The results show that with vane number increasing,the demisting efficiency increases firstly,and then tends to be stable,while the pressure drop increases gradually.With vane angles increasing,the demisting efficiency increases as the growth rate decreases,and the pressure drop increases as the growth rate increases.With inner cylinder diameters increasing,the demisting efficiency and the pressure drop both increase slowly.With ring gap widths increasing,the demisting efficiency and pressure drop both decrease gradually.In particular,when the inlet velocity is large,the demisting efficiency decreases faster.With cyclone part heights increasing,the demisting efficienc firstly increases rapidly,and then tends to be stable,while pressure drop increases gradually.With the increase of inlet velocities,the demisting efficiency increases and pressure drop increases rapidly.The primary and secondary order of effects of various parameters on the demisting efficiency is cyclone part heights,vane angles,vane numbers,inlet velocities,inner cylinder diameters and ring gap widths.The primary and secondary order of effects of various parameters on the pressure drop is inlet velocities,vane angles,ring gap widths,cyclone part heights,vane numbers and inner cylinder diameters.The optimal parameter combination of demister through orthogonal design method is “vane number 18,vane angle 60°,inner cylinder diameter 152 mm,ring gap width 18 mm,cyclone part height 1136 mm and inlet velocities 3m/s”.Compared with the reference demister,the demisting efficiency increases by 9.23% and pressure drop increases by 25.74 Pa under optimal demister.