Production process and system of ultralow NOx emission of pellet flue gas

Abstract

The invention provides a production process and a system of ultralow NOx emission of pellet flue gas. A set of flue gas circulation system is additionally arranged, the flue gas discharged from an airdraft drying section is taken as cooling air to be further conveyed to an air inlet of an annual cooling two-section, meanwhile, a reducing agent is sprayed at the top located at the annular coolingtwo-section, the reducing agent reacts with NOx in the flue gas subjected to the annular cooling two-section, and SNCR denitration is realized; and or the gas discharged from an air outlet of the annular colling two-section is conveyed to a preheating one-section of a chain grate machine after passing through a SNCR treatment system; the high-temperature characteristic of discharging the flue gasfrom the air draft drying section is utilized, meanwhile, the condition of high-temperature sintering ore in the annual colling two-section is utilized, and the part of the flue gas is treated by adopting the SNCR. By the adoption of the technical means, an enterprise atmospheric pollutant emission limit value on the production pressure of pellet roasting equipment requirements can be reduced to acertain extent, and the process and the system have the characteristics of being decreasd in investment, low in operation cost and remarkable in NOx emission reduction effect.

Description

technical field [0001] The invention relates to a pellet production technology, in particular to a production process and production system for ultra-low NOx emission of pellet flue gas, and belongs to the technical fields of pellet production and environmental protection. Background technique [0002] Pellets are the main iron-containing charge for blast furnace ironmaking in my country. In 2015, the output of pellets in my country was 128 million tons. Compared with sinter, due to the low energy consumption and relatively friendly environment of the pellet production process, and the product has the advantages of good strength, high grade, and good metallurgical properties, it can increase production and save coke when applied to blast furnace smelting, and improve ironmaking technology and economy Indicators, reducing the cost of pig iron, and improving economic benefits, so pellets have been vigorously developed in my country in recent years. [0003] my country's pellet...

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Problems solved by technology

[0009] In view of the existing problems in the prior art, in order to solve the NO x It is difficult for enterprises to accept problems such as substandard emissions and high cost of adding denitrification devices at the end. This patent proposes to add a set of flue gas circulation system, and the flue gas discharged from the extraction and drying section will be further transported to the second section of ring cooling as cooling air. At the same time: spray the reducing agent at the top of the second ring cooling section, the reducing agent and the NO in the flue gas after the second ring cooling section x reaction to realize SNCR denitrification; or, the gas discharged from the air outlet of the second stage of the ring cooling passes through the SNCR treatment system and then is sent to the preheating stage of the chain grate

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