Internal-external circulation system and method for sintering flue gas

Abstract

The invention provides an internal-external circulation system for sintering flue gas. The internal-external circulation system comprises an internal circulation device, an external circulation deviceand a desulfurization and denitrification device, wherein the internal circulation device is connected with a middle-front section flue of a main flue of a sintering machine, and first purified fluegas is obtained and is then circulated into the sintering machine; the outer circulation device is connected with a machine head flue and a middle-rear section flue of the main flue of the sintering machine, second purified flue gas is obtained, one part of the second purified flue gas is circulated into the sintering machine, and the other part of the second purified flue gas enters the desulfurization and denitrification device; and flue gas from the middle-rear section flue exchanges heat with flue gas from the middle-front section flue and then enters the outer circulation device. The invention further provides an internal-external circulation system for sintering flue gas. According to the invention, the circulation rate of the sintering flue gas is increased from 20% to 60% or above,the utilization rate of waste heat is increased, the concentration of NOx in the flue gas is reduced, a two-stage CO removal reaction is achieved, and a large amount of investment and operation costis saved.

Description

technical field [0001] The invention belongs to the technical field of ultra-low emission of flue gas in the iron and steel industry, and in particular relates to an internal and external circulation system and circulation method of sintering flue gas. Background technique [0002] The sintering process in the iron and steel industry emits a lot of pollutants. As an important way to reduce pollutant emissions, sintering flue gas circulation technology has proposed a variety of recycling processes at home and abroad, including LEEP, Eposit, EOS and Xinri Iron and other processes; domestic enterprises such as Ninggang, Shagang, Shougang, Baosteel, Yonggang, Qiangang, and Changgang have all implemented it. [0003] At present, the flue gas circulation technology of sintering machine is roughly divided into two technical methods: flue gas internal circulation technology and flue gas external circulation technology. [0004] Flue gas internal circulation technology features: 1. ...

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Problems solved by technology

[0008] The purpose of the present invention is to provide a sintering flue gas internal and external circulation system and circulation method, so as to at least solve the problems of low waste heat utilization rate and insufficient circulation rate when sintering flue gas is internally circulated or externally circulated alone

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