| With the rapid development of steel industry in recent years, environment pollution is getting worse and worse and great importance on environment treatment has been attached by the government.In the meanwhile, the requirements for environment protection are higher and higher, exerting an increasing pressure in the area of environmental protection for the steel industry. NOx generated by sintering accounts for more than 50% of the NOx emission in steel industry. The sintering flue gas is different from other industrial waste gas and has its own characteristics, making the treatment of the sintering NOx urgent.This study focuses on the reduction of sintering NOx and systematically studies the NO emission law of different kinds of fuel and the modified ones.Using the mini-horizontal heating furnace, the law of NO emission and the effects of temperature, grain size and oxygen concentration are systematically investigated. The result shows that NOx emission during sintering is mostly generated from the fuel; the highest nitrogen conversion of pulverized coal is achieved at 800?, then decreases with an increase in temperature. The nitrogen conversion of coke increases when temperature increases below 900? and then decreases with a continuing increase above 900?. The sintering fuel between 3-5 mm has the highest nitrogen conversion; when the oxygen concentration is 15%, the concentration and total of NO reach the highest as same as the nitrogen conversion of fuel.The burning experiment is carried out using coke modified by different kinds of reagent. The result shows that the optimum temperature for emission reduction is 900?. Excessive oxygen concentration is harmful. The addition of calcium base compound has a limited effect on NO emission reduction and the highest emission reduction rate can reach 23.76% which can only be achieved when 2wt% CaCO3 is added. The addition of the reagent that can volatilize the amino has an obvious effect to minimize NOx emission All the tested reagent have the optimum temperature ranging between 900±50?. The effect of emission reduction decreases if the temperature is too high or too low. When the oxygen concentration is 5%?21%, there are differences among the optimum effect of different reagent. Owing to the fact that the reagent itself volatilizes amino, there is an increase in NO concentration when the addition is excessive and the emission reduction rate becomes minus. The capability of the tested reagent in controlling the emission of NOx during the experiments can be shown as below:urea> ammonium chloride> ammonium sulphate> ammonium carbonate> ammonium bicarbonate. The optimum temperature of Ca(CH3COO)2 modified coke is 1100?. The NO reduction rate decreases when the oxygen concentration increases and when the amount of addition increases.The law of NO emission is studied by using biomass fuel and charcoal as a substitute of the sintering fuel. The result shows that there is a low NO emission when the biomass fuel and charcoal burns. The best NOx control effect can be achieved under 900?. Low oxygen concentration and high substitute ratio both can have a positive effect on the NO emission reduction.By sintering the most effective modified fuels, their influence on the NO emission reduction performance and on the quality index of the modified fuel is studied. The result shows that 2wt% CaCO3 modified fuel?4wt% urea modified fuel? 4wt%NH4Cl modified fuel?2wt% Ca(CH3COO)2 modified fuel?20wt% biomass substitute fuel and 20wt% charcoal substitute fuel all have a promoting effect on the NO emission reduction. Among them,20wt% biomass substitute fuel has the best result. Meanwhile, the modified fuel doesn't influence much on the quality index of the sintered ore and has good prospects for application on the NO emission reduction during sintered. |
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