Cement burning apparatus, and method for denitrating exhaust gas from cement kiln

Abstract

[Problem] To efficiently reduce the concentration of NOx in an exhaust gas from a cement kiln while keeping the burned state at a good level regardless of the type of a calcining furnace to be used. [Solution] A cement burning apparatus (1) equipped with a burner (14) for blowing a fuel (F3) and combustion air into a kiln tail part (4) of a cement kiln (5) to burn the fuel. It becomes possible to reduce NOx, which is contained in an exhaust gas from the cement kiln, in a low-oxygen zone in the kiln tail part, and it also becomes possible to improve the decarbocxylation efficiency of a cement raw material due to the burning of the fuel. The burner may be equipped with a swirl vane (a swirl means) (14b) for swirling a mixed flow of the fuel and the combustion air. It is preferred that the amount of the fuel to be supplied into the kiln tail part of the cement kiln is 20% or more and less than 50% of the amount of the fuel to be supplied into a calcining furnace (3) that is provided in the cement kiln. The fuel to be supplied into the kiln tail part of the cement kiln may comprise at least one of pulverized coal, a heavy oil and a burnable waste material.

Description

technical field [0001] The present invention relates to a technique for reducing the concentration of nitrogen oxides (hereinafter referred to as "NOx") in combustion gas discharged from a cement kiln. Background technique [0002] In the exhaust gas of a cement kiln, NOx originating from the high-temperature region of the firing zone is contained, and when the concentration of NOx is high, denitration agents such as urea and ammonia are added, or it is denitrated by the reduction action caused by combustion in the calciner furnace. Reduce NOx concentration. However, in the method of using urea as a denitrification agent, since the price of urea is high, the running cost increases significantly. In addition, when only urea is added, the denitrification efficiency is low, and there is a concern that excess ammonia that has not reacted with NOx is discharged out of the system as it is. [0003] Therefore, in Patent Document 1, a method for reducing the NOx concentration in t...

AI Technical Summary

Problems solved by technology

However, in the method of using urea as a denitrification agent, the running cost is greatly increased due to the high price of urea.

In addition, when only urea is added, the denitrification efficiency is low, and there is a concern that the remaining ammonia that has not reacted with NOx will be discharged out of the system as it is.

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