Research On The Influence Of Combustion Coupling State And Combustion Parameters On Pollutant Emissions

The coal used in layer combustion（sintering,smelting,loose coal combustion,etc.）accounts for 40%of the coal used in China.At present,the combustion rate of this coal is generally low,and this phenomenon leads to the concentration of original pollution emissions and the cost of remediation being maintained at high levels.Existing studies have not paid much attention to the coupling state among the combustible particulate matter and combustible gas emitted by layer combustion,the auxiliary gas and the fuel,and the influence mechanism of such coupling state on combustion rate and combustion pollution emissions is unclear,which forms a theoretical blank area for the innovation of the emission reduction technology of support layer combustion.To this end,this topic takes coal layer combustion as the main research object,and improves the coupling model of traditional combustion furnace,finally obtains two new models of"lower into side discharge"and"side into side discharge".On this basis,three different furnace types are used to construct different coupling states between combustion participants,and the change characteristics of combustion pollution emissions are measured.Through the study of combustion coupling state,the improvement mechanism of combustion efficiency and emission level is studied.The results show that different combustion coupling states can enhance the combustion efficiency of combustible particulate matter and combustible volatile matter in combustion pollution emissions by constructing the ordered coupling between fuel,auxiliary gas and pyrolysis gas to different degrees,and thus improve the layer combustion of coal.In addition to the combustion coupling model,different combustion parameters in the combustion process also have a great correlation with the combustion state,thus affecting the level of pollutants discharged from combustion.In this thesis,the control variable experiment method is adopted to further explore the influence mechanism of pass air rate and fuel component on combustion efficiency and combustion pollutant control level respectively under fixed combustion conditions.It is found that the volume fraction ratio of combustible and combustion supporting components is determined by the value of the passing air rate.The appropriate passing air rate can improve the reaction force of combustion reaction,adjust the internal flow field of the combustion furnace,and improve the coupling state of fuel-gas-pyrolysis gas.The mass ratio of volatile and fixed carbon in the analysis components of fuel industry determines the mass ratio of pyrolysis gas-phase combustion components and solid-phase combustion components in the combustion process,thus affecting the emission level of combustible pollutants.In addition,the content of specific element in fuel determines the emission level of corresponding pollutant which is mainly composed of this element.The excellent combustion coupling model and the appropriate passing air rate can realize the orderly coupling of fuel,auxiliary gas and pyrolysis gas,thus complete the huge emission reduction of combustible pollutants.Among them,the CO emission level can be reduced by 3 orders of magnitude to 42.7 ppm;Non-methane total hydrocarbon and CH₄ emission levels can be reduced by 1-2 orders of magnitude to 2.5 ppm and 0.5ppm,respectively;The emission level of fine particulate matter can be reduced by 2orders of magnitude to 2.7 mg/m³.The above four original emission levels are all lower than the maximum emission standard set by the state.SO₂ and NO_X are related to fuel occurrences,and the combustion coupling state has no significant improvement on their emission levels,but the emission reduction can be achieved by adjusting the fuel type and its ratio.The thesis has 46 figures,6 tables and 101 references.