Numerical Simulation Study Of Desulfurization Wastewater Evaporate In Flue Gas

The flue gas desulfurization technology of thermal power plant is wet limestone-gypsum process in China.However,due to the process characteristics of wet desulfurization,a large amount of desulfurization waste water will be produced after desulfurization.The traditional chemical precipitation method can't completely remove C1-,the method hasn't met the environmental requirements of zero discharge of wastewater.Therefore,the flue gas evaporation process that can realize zero discharge of the desulfurization wastewater starts to be the focus of attention,because of the lower investment operation cost.The flue gas evaporation system that has been put into operation has been found that the system has some problems,such as unstable operation,insufficient adaptability to the unit and coal,improper arrangement of atomizing nozzles,fouling on the flue wall.Against the above problems,A 300 MW coal-fired unit in a power plant was taken as an example.The CFD software was used to simulation the injection system of desulfurization wastewater in flue duct.The effects of atomized particle size,flue gas temperature,flue gas flow rate,droplet velocity and spray gun arrangement on droplet evaporation were analyzed.The flue gas velocity distribution,pressure distribution and fly ash concentration distribution in the flue are analyzed.The flue gas velocity field and the fly ash concentration field are optimized by installing the deflector in the curve part.Through the coefficient of variation,the effect of optimizing the flow field in the installation of deflector is compared.The results of this study show that atomization particle size and flue gas temperature are important factors affecting the evaporation characteristics of the droplet.When the flue gas temperature is low,the smaller atomization particle size is required to ensure the complete evaporation of the droplets.There are obvious uneven distribution phenomena of pressure and velocity in the curved part of the flue,resulting in the fouling on the flue wall.The installation of deflectors can improve the flow field distribution in the flue.