The Research On Evaporation And Concentration Of Desulfurization Wastewater By Flue Gas

The desulfurization wastewater has the characteristics of high suspended solids,high salinity,unstable water quality,acidity and traces of heavy metals.The zero-emission treatment technology of desulfurization wastewater has always been one of the research hotspots in the field of environmental protection.Based on the analysis of the existing treatment technology of desulfurization wastewater,this paper proposed a method that utilizes both waste heat and concentrated desulfurization wastewater,which is a process to evaporate and desulfurize wastewater using the bypass gas-liquid contact tower for directly contacting the flue gas.In this paper,a heat and mass transfer model were established for gas directly contacted with liquid.The hot air and sodium chloride solution were used to directly contact the heat and mass transfer process.The changes of gas-liquid heat transfer,mass transfer coefficient and system evaporation with different operating conditions were investigated.The gas-liquid mass transfer coefficient and heat transfer coefficient increased with the increase of air flow rate,air temperature,solution flow rate,solution temperature and inlet air moisture content.But decreased with the increase of solution salinity.Air flow rate and air temperature had significant effects on gas-liquid mass transfer coefficient and heat transfer coefficient.The amount of system evaporation increased with increasing air flow,air temperature,solution flow rate,and solution temperature.But decreased as the increasing of the inlet air moisture content and solution salinity.The increase of air flow had a significant effect on the amount of evaporation.The bypass gas-liquid contact was designed to directly contact the evaporation and desulfurization wastewater with flue gas and the process was carried out on site.Using the 68670 Nm~3/h flue gas can make the TDS of 5 m~3/h desulfurization wastewater more than 200,000 mg/L by a gas-liquid contact tower with 4 meters diameter.Under the experimental conditions,the concentration ratio of the desulfurization wastewater reaches more than 10 times.The concentrated liquid of the desulfurization waste water is directly sprayed into the fluidized bed dryer.As the inert particles continuously roll and collide,the solid thin layer falls off from the particle surface and is further pulverized and dried into a powder.The purpose of concentrating desulfurization wastewater by low temperature flue gas evaporation is realized.The research results provide a new idea for the treatment of desulfurization wastewater and lay a foundation for industrial application.