Research On Nitrogen Oxide Control Technology In Sintering Process Of Vanadium Titanium Magnetite

With the improvement of environmental protection requirements and the introduction of more stringent emission standards,the steel industry is facing the challenge of strengthening control of NOx emissions.This paper focuses on the reduction treatment of nitrogen oxides in the sintering process of vanadium-titanium magnetite,the source of NO during sintering,the influence of sintering process parameters on NO formation,and the effect of additives on the formation of NO in the mixture.A small horizontal reheating furnace test system was used to study the effect of NO Emission regularity and the influence of temperature,particle size,oxygen concentration and air velocity on the NO emission concentration during the combustion of the coke.The test results show that the main source of nitrogen in the sinter mixture comes from the fuel,which accounts for 73%of the total nitrogen content.When the sintering material is burned at the same temperature,the NO concentration of coal powder and coke powder is the highest.With the increase of combustion temperature,the conversion rate of NO increases gradually when coke is burned.With the increase of coke size,the conversion rate of NO increases first and then decreases.When the size of coke is 3mm~5mm,the conversion of NO reaches the maximum value of 25.79%.With the increase of O2 content,the conversion rate of NO increases first and then decreases,when the content of O2 is 15%,The conversion rate of NO reaches 30.2%,and the conversion rate of NO decreases with the increase of air velocity.The influence of sintering process parameters on NO generation and main indexes of sintering was studied by sintering cup test system.The test results show that with the increase of basicity of the sintering mixture,the concentration of NO in the flue gas decreases slightly,the sintering speed,the utilization coefficient,the sintering product rate and the drum strength are obviously increasing.With the increase of the mixture water,the concentration of NO in the flue gas has a slight decreasing trend,the sintering speed and the utilization coefficient are slightly higher,the sintering yield and the drum strength are decreasing.With the increase of the flux proportion of active ash,the concentration of NO in the sintering flue gas has a tendency to decrease,the sintering speed,the yield,the drum strength and the utilization coefficient are obviously increased.With the increase of the thickness of the material,the concentration of NO in the sintering flue gas has a tendency to decrease,the yield and the drum index of the sintered ore gradually increase,and the sintering speed and the utilization coefficient gradually decrease.With the coal sintering speed and the utilization coefficient gradually decreasing;along with coal.With the decrease of powder and coke powder,the concentration of NO in the sintering flue gas decreased significantly,the yield and drum strength decreased gradually,and the sintering utilization coefficient gradually increased first and then decreased.With the increase of the proportion of fuel in the coke powder,the concentration of NO in the sintering flue gas gradually decreased,and the sinter grade,the finished product rate and the sintering machine utilization coefficient increased slightly,and the sinter drum index did not change significantly.The influence of additives in the mixture on the main indicators of NO generation and sintering was studied by sintering cup test system.The results showed that after adding volatile ammonia,the total amount of NO emission in the flue gas decreased to a certain extent,and the effect of reducing the emission of urea and ammonium chloride was the best.With the increase of the amount of urea and ammonium chloride,the total amount of NO emission decreased gradually.When the amount of urea added to 0.9wt%,the total amount of NO emission decreased from 34.4g to 22.4g,and the emission reduction rate reached 36%.When the addition of ammonium chloride was 0.7wt%,the total amount of NO was reduced from 34.4g to 24.8g,and the emission reduction rate was 28%.After adding calcium acetate and other hydrocarbon additives in the sinter mixture,the total emission of NO in the flue gas decreased obviously.With the increase of calcium acetate addition,the total amount of NO emission decreased significantly after a small decrease.When the calcium acetate added to 0.9wt%,the total amount of NO decreased from 34.4g to 18.9g,and the emission reduction rate reached 45%.After adding the biomass substitute fuel to the sintering mixture,the total amount of NO emission in the flue gas is significantly reduced.With the increase of the fuel ratio,the total amount of NO is gradually reduced.When the replacement ratio of fuel reaches 50%,the total emission of NO is reduced from 34.4g to 21.8g,and the emission reduction rate is 36.6%,but the sintering speed,yield,drum strength and utilization coefficient are at the same time.The main technical and economic indicators have been reduced to a certain extent.