Study On Crystallization Process And Crystal Morphology Control Of By Products Of Simultaneous Desulfurization And Denitrification By Magnesium Method

Pollutants such as sulfur dioxide（SO₂）and nitrogen oxides（NO_x）produced by coal combustion are the main pollutants that cause atmospheric environmental problems such as photochemical pollution,acid rain,ozone,and regional haze weather in my country.As the largest user of coal consumption,The flue gas treatment of coal-fired boilers has become the focus of air pollution control in my country.In recent years,the wet limestone/gypsum desulfurization（WFGD）combined selective catalytic reduction denitrification（SCR）process has been widely used in many coal-fired power plants,effectively controlling the emission of SO₂ and NO_x in the flue gas,and alleviating the atmosphere The situation of pollution is increasing,but the form of air pollution prevention and control in my country is still very severe.The main reason is that the flue gas emissions of small and medium-sized industrial boilers represented by steel,cement,and glass have not been effectively controlled.Due to the complex composition of industrial boiler flue gas,unstable working conditions,low automation,and strong flue gas corrosion,etc.Characteristics,the mainstream desulfurization and denitrification technology in power plants cannot achieve an effective removal effect,so how to control the pollutant emissions of small and medium-sized industrial boilers has become the focus of current research.In the preliminary research,this research group proposed a simultaneous desulfurization and denitrification technology based on the magnesium method,which has low investment and operating costs,simple maintenance and operation,strong coal type adaptability,and high desulfurization and denitrification efficiency,making this technology suitable for small and medium-sized industries.Popularization in boilers is possible,but the ion concentration in the desulfurization and denitration slurry is high,and direct discharge easily causes environmental pollution and resource waste.How to deal with the slurry has become a key issue that restricts the practical application of this technology.At present,the commonly used slurry treatment methods such as two-alkali method and evaporation crystallization have the problems of low product quality and high energy consumption.For this reason,we have proposed a vacuum crystallization treatment method.Compared with the conventional evaporation crystallization method,this method The magnesium salt with high utilization value can be recovered with lower energy consumption,thereby reducing the cost of desulfurization and denitrification of enterprises.This article takes Mg²⁺//SO₄^2-,Cl^--H₂O system,Mg²⁺//SO₄^2-,NO₃^--H₂O system,Mg²⁺//SO₄^2-,NO₃^-,Cl^--H₂O system as the research object,based on the method of vacuum crystallization,The effects of different evaporation rates and stirring rates on the crystal morphology were studied.At the same time,the effects of seed crystal addition,Fe³⁺and Fe²⁺content,organic matter type and addition amount on the crystal morphology were studied.At the same time,the vacuum under different evaporation rates was investigated.The energy consumption of crystallization.This research determines the best process conditions for crystallization,improves the quality of crystal products,and provides a theoretical basis for the next step of research and industrial production.