A waste gas circulation denitrification method for iron ore pellets

Abstract

The invention discloses a waste gas cyclic denitration method for iron ore pellets. According to the method, NOx-containing flue gas generated by the iron ore pellets in the production process of theiron ore pellets is cycled to a medium and low temperature cooling zone, and at the medium and low temperature cooling zone, ammonia spraying denitration is carried out. The specific method comprises:converging waste gas at a down-draft drying zone with high-sulfur flue gas at a preheating warming zone, of which SO2 concentration is greater than 300mg / m<3>; and sequentially carrying out dust removal and desulfuration purification, desulfurizing to SO2 concentration of 50mg / m<3> or below; then converging the obtained gas with front-zone waste gas at the preheating warming zone, of which SO2 concentration is lower than 300mg / m<3>; cycling the obtained gas into the medium and low temperature cooling zone to use as a cooling medium; before cycled waste gas enters a cooling-zone material layer, spraying NH3; then filling the cycled waste gas into the material layer to carry out SCR denitration; controlling a molar ratio of NH3 to NO within a range of 0.3 to 0.5, so as to realize NOx emission reduction by 15% to 25%.

Description

technical field [0001] The invention relates to a denitrification method during the formation of iron ore pellets, in particular to a waste gas circulation denitrification method for iron ore pellets, and belongs to the technical field of iron and steel metallurgical pellet technology. Background technique [0002] Pellets are an essential raw material in the steel production process, and the pelletizing process is one of the main processes in the steel production. With the development of my country's iron and steel industry, the production of pellets is increasing year by year. However, the pelletizing process will produce a large amount of NOx, SO 2 Pollutants such as dust and dust have put forward a test for the clean production and sustainable development of the steel industry. In June 2017, the Ministry of Environmental Protection issued the revised announcement of the "Steel Sintering and Pelletizing Industry Air Pollutant Emission Standards", which further reduced t...

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Problems solved by technology

[0005] In view of the incompatibility of desulfurization and denitrification at the end of the existing pellet flue gas and the problem that the NOx concentration in the flue gas after denitration by SNCR in the preheating section is still not up to the standard, the purpose of the present invention is to provide a high-efficiency denitrification of iron ore oxidation pellet exhaust gas. The method, on the basis of the existing desulfurization process, realizes the compatibility of desulfurization and denitrification, while reducing the treatment capacity of the flue gas, and without additional denitrification facilities, the flue gas can be economically and efficiently denitrified

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