Analysis And Numerical Simulntion Of Simultaneous Desulfurization And Denitrification In Flue Gas Circulating Fluidized Bed

Flue gas circulating fluidized bed desulfurization is a widely used flue gas desulfurization technology in coal-fired thermal power plants.Due to the continuous improvement of pollutant emission standards for coal-fired boilers,not only higher SO2 emission concentration but also nitrogen oxides are required.At this stage,the overall requirement is to meet the natural gas emission standard("50355" emission standard)of "Air Pollutant Emission Standard for Thermal Power Plants"(GB13223-2011).That is,SO2<35mg/m3,NO<50mg/m3 and smoke<5mg/m3.Therefore,the coal-fired thermal power plant using flue gas circulating fluidized bed desulfurization technology has brought the requirement of upgrading within a time limit.The main content of this paper is an example analysis of simultaneous desulfurization and denitrification process in a thermal power plant,and numerical simulation of simultaneous desulfurization and denitrification process in flue gas circulating fluidized bed is carried out to understand the internal working conditions of simultaneous desulfurization and denitrification in flue gas circulating fluidized bed.The main contents and conclusions of this paper are as follows:(1)Understanding the research and application development of flue gas desulfurization technology for coal-fired boilers at home and abroad,semi-dry flue gas circulating fluidized bed desulfurization process analysis,low temperature denitrification(COA)process analysis.(2)According to the actual operation of No.3 boiler unit in a thermal power plant,the operation of desulfurization and low temperature denitrification in semi-dry flue gas circulating fluidized bed is analyzed,and the by-products of desulfurization and denitrification are also analyzed.The conclusion is that the simultaneous desulfurization and denitrification technology of flue gas circulating fluidized bed can ensure that the pollutant emission concentration of coal-fired boilers reaches the "50355" emission standard,which has a demonstration effect for ultra-low emission renovation of domestic coal-fired thermal power plants.(3)In this paper,we use Design Modeler to build three-dimensional solid model,and use ANSYS Icem to mesh.Based on Fluent software,the removal process of SO2 and NO in flue gas circulating fluidized bed was simulated by using chemical component transport model.Considering the characteristics of flue gas circulating fluidized bed and the chemical reaction characteristics of high concentration and full mixing,the finite rate/eddy dissipation model is used to simulate the reaction.Through numerical simulation,the working conditions of flue gas circulating fluidized bed can be clearly understood,including pressure change,velocity change and composition change of reactants.(4)Flue gas circulating fluidized bed simultaneous desulfurization and denitrification technology can be an effective,low cost,less space occupied,no waste water discharge ultra-low emission transformation technology route.