A zoned tissue combustion self-denitration system and process with a reduction furnace and a decomposition furnace

Abstract

The invention discloses a self-denitrification system and process for zoned tissue combustion with a reduction furnace and a decomposition furnace. A reduction furnace is installed between the kiln tail smoke chamber and the decomposition furnace. The bottom of the calciner cone is connected to form a horizontally partitioned combustion environment with a central oxygen-rich zone and a peripheral low-oxygen zone on the calciner cross-section; The space inside the calciner below the upper branch pipe is the weak reduction zone, and the space inside the calciner above the upper branch pipe of the tertiary air is the burnout zone, forming a longitudinal gradient combustion environment combining strong reduction zone-weak reduction zone-burnout zone. The horizontal partition combustion environment is realized by the tertiary air entering vertically upward from the bottom center of the calciner, and the flue gas is realized by the spiral tangential rotating air entering from the side of the calciner; the vertical gradient combustion environment is realized by fuel graded feeding and tertiary air distribution. The present invention realizes self-denitrification through zoned organization combustion as a whole, and improves self-denitrification efficiency.

Description

technical field [0001] The invention relates to the technical field of flue gas denitrification in the cement industry, in particular to a zone-organized combustion self-denitration system and process with a reduction furnace and a decomposition furnace. Background technique [0002] The calciner is the key equipment in the cement production process. The main component of cement raw meal is calcium carbonate, and the carbonate in cement raw meal is decomposed into oxides in the calciner, which provides a basis for the subsequent clinker sintering reaction in the rotary kiln. Since the decomposition of carbonate needs to absorb a large amount of heat, a certain amount of fuel needs to be fed into the decomposition furnace to supply it. Generally speaking, the fuel in the calciner accounts for about 60% of the fuel consumption in the entire cement clinker calcination process. The combustion status of the fuel in the decomposition directly affects the product energy consumpti...

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Problems solved by technology

[0013] (1) In the existing linear calciner, the kiln gas enters directly from the bottom of the calciner. Even if the fuel is graded and burned, a reduction zone is formed at the cone of the calciner, which has a certain effect on reducing NOx in the flue gas from the kiln. However, due to The flue gas from the kiln enters the furnace directly, the space of the oxygen-poor combustion zone is limited, the residence time of the denitrification reaction is short, and the denitrification efficiency is generally about 30%.

[0014] (2) The fuel combustion rate of the existing calciner is limited by the temperature of the combustion zone and cannot be burned quickly. It is necessary to increase the volume of the calciner and prolong the combustion time to meet the demand for combustion. On the one hand, it increases investment and space occupation, and on the other hand Increased equipment surface heat dissipation energy consumption

[0015] (3) The temperature in the combustion zone of the calciner is limited by the crust on the furnace wall, which makes it difficult to further increase the temperature in the combustion zone in the existing technology

When the temperature in the combustion zone is too high, the raw material is prone to liquid phase at high temperature, resulting in skinning problems on the furnace wall

If the combustion temperature of the calciner is too high, it is easy to burn out the refractory material of the furnace wall

[0016] (4) The calciner fuel staged combustion method can only reduce the NOx produced in the rotary kiln, but cannot reduce the NOx produced by the combustion of the fuel itself in the calciner

Moreover, it is relatively difficult to ignite and ignite the fuel in the calciner, which is likely to cause fluctuations in working conditions and affect the stability of the cement production process.

[0017] (5) The method of gradient combustion in the existing calciner is limited to the interior of the calciner

Restricted by factors such as the volume of the calciner and the space of the site, the overall denitrification effect needs to be improved

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