Combined denitration system and method for preheating section and tail flue of steel rolling heating furnace

Abstract

The invention discloses a combined denitration system for a preheating section and a tail flue of a steel rolling heating furnace. The combined denitration system comprises a heating furnace, a steelpusher, a spraying device, a high-temperature air preheater, an SCR reactor, a low-temperature air preheater, an SCR mixer, an SNCR mixer, an exhaust hood, an air compressor, a dilution fan and a reducing agent storage device. The reducing agent storage device is connected with the SCR reactor through a second reducing agent pipeline via the SCR mixer; the air compressor is connected with the spraying device through an air pipeline via the SNCR mixer; the dilution fan is connected with the SCR mixer and the SCR reactor through a dilution pipeline; and a temperature control bypass flue is arranged between the inlet and the outlet of the high-temperature air preheater. According to the combined denitration process combining SNCR primary denitration arranged at the preheating section of the heating furnace and SCR secondary denitration arranged at the tail flue, the use amount of a reducing agent is controlled through an SCR regulating valve and an SNCR regulating valve, the use amount ofa catalyst is greatly reduced, the problem that NOx emission exceeds the standard in the roller changing period of the heating furnace can be effectively solved, and the investment and operation costof the system are reduced.

Description

technical field [0001] The invention belongs to the technical field of flue gas denitrification, and in particular relates to a combined denitrification system and method of a preheating section and a tail flue of a steel rolling heating furnace. Background technique [0002] Nitrogen oxides (NO x ) as a major atmospheric pollutant generally includes nitric oxide (NO), nitrogen dioxide (NO 2 ), nitrogen trioxide (N 2 o 3 ), nitrogen pentoxide (N 2 o 5 ), among which the main air pollution is NO and NO 2 . In recent years, with the increase of energy consumption, its emissions are also increasing year by year, and the environmental problems caused by it are also becoming more and more prominent. As the national environmental protection policy restricts the emission of air pollutants more and more strictly, for nitrogen oxides The reduction of emissions has also been gradually implemented in regulations and policies to strictly control the nitrogen oxides produced in th...

AI Technical Summary

Problems solved by technology

[0004] (1) Steel rolling production fluctuates greatly, and the flue gas volume fluctuates greatly. When the flue gas volume fluctuates, it is difficult to accurately control the ammonia gas injection volume, and the ammonia escape index often exceeds the standard;

[0005] (2) During the roll changing process of the steel rolling heating furnace, the flue temperature drops below the working temperature of the medium and low temperature denitrification catalyst, which makes the catalyst invalid and leads to NO x Exceeding emission standards;

[0006] (3) The investment and operating costs of the flue gas denitrification system of the steel rolling heating furnace are high, which leads to an increase in the production cost of the steel rolling production enterprise

Images