Study On Defogging Performance Of Mist Eliminator In Wet Flue Gas Desulfurization System

The technology of wet flue gas desulfurization is used in the tail gas treatment of boilers widely.However,the flue gas after wet desulfurization carries a large amount of droplets containing contaminants.In order to remove these liquid droplets,a vane type mist eliminator is generally installed on the top of the desulfurization tower in actual situation.The vane type mist eliminator has a large amount of advantages for the droplet particles with larger diameter,such as large processing capacity,high separation efficiency,low pressure drop and less clogging.The main methods for the research of defogger are experimental research and numerical simulation research.However,the experimental research cannot be widely applied because the high cost and complicated operation process and so on.In this paper,the numerical simulation method is used to simulate the gas-liquid two-phase flow in four types of demister channel,including plate type mist eliminator,fold line type defogger,ordinary corrugated board defogger and hook corrugated board defogger.The defogging efficiency and pressure loss of each defogger were calculated under different working conditions.And its variation law and reason of demisting performance with each primary influence factor were analyzed based on the simulation results.The results show that the performance of the defogger is significantly influenced by the initial velocity and droplet diameter of the fluid,as well as the shape,spacing and blade deflection angle of the demister.The defogging efficiency and pressure loss of each mist eliminator increase as the initial velocity of the fluid grow.When the diameter of the droplet in the fluid is larger,the demisting efficiency of the mist eliminator is better.However,the pressure drop in the defogger is not influenced by the diameter of the droplet.As for these four types of defogger,the pressure drop from high to low is: hook corrugated plate defogger,fold line defogger,folding plate defogger,ordinary corrugated board defogger.And the defoggingefficiency of the hook corrugated board defogger is much higher than that of the other three types of defogger.When the blade pitch and blade deflection angle are larger,the demisting efficiency of the mist eliminator is worse,the pressure drop is less.Compared with four types of defogger,the hooked corrugated board demister has the best defogging performance.Finally,according to the situation of poor separation effect for the droplets under 15?m in the hook corrugated plate demister,the theoretical design of adding a baffle in the defogger is proposed,and the defogger is also optimized by the simulation method.The separation efficiency of droplets under 10 ?m can reach above 90%,but the results show that the pressure drop is also greatly increased.In this paper,the research mainly provides a theoretical basis and numerical reference for the design and optimization of the defogger,which can be used to guide the future study of defogger.