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A self-denitration system and process for combustion and self-denitration in the dense and thin oxygen-containing zones of the calciner

A technology of organizing combustion and decomposition furnace, which is applied in the field of flue gas denitrification in the cement industry. It can solve the problems of limited space in the oxygen-poor combustion zone, short residence time of denitrification reaction, and burnout of furnace wall refractory materials, etc., and achieves strong operability and Practicality, reducing the cost of environmental protection treatment, and improving the effect of fuel combustion speed

Active Publication Date: 2021-05-04
TIANJIN CEMENT IND DESIGN & RES INST
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AI Technical Summary

Problems solved by technology

[0011] (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%.
[0012] (2) The combustion speed of the existing calciner is limited by the temperature of the combustion zone and cannot be burned out quickly. It is necessary to increase the volume of the calciner and prolong the combustion time to meet the demand for burnout. On the one hand, the investment and space occupation are increased, and on the other hand, the The heat dissipation energy consumption of the equipment surface
[0013] (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
[0014] (4) The combustion temperature of the decomposition furnace is too high and it is easy to burn the refractory material of the furnace wall
[0015] (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

Method used

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  • A self-denitration system and process for combustion and self-denitration in the dense and thin oxygen-containing zones of the calciner
  • A self-denitration system and process for combustion and self-denitration in the dense and thin oxygen-containing zones of the calciner
  • A self-denitration system and process for combustion and self-denitration in the dense and thin oxygen-containing zones of the calciner

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Experimental program
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Effect test

Embodiment 1

[0058] see Figure 1~4 , the embodiment of the present invention provides a denitrification system for denitrification by combustion in the rich and light oxygen-containing zones of the calciner, including a rotary kiln, a kiln tail smoke chamber 6 connected to the kiln tail of the rotary kiln, a calciner 1, a kiln tail smoke chamber 6 and a decomposition furnace. The kiln gas flue 21 of the furnace 1 and the tertiary air duct 3; the calciner 1, the kiln gas flue 21 and the tertiary air duct 3 are all equipped with refractory materials.

[0059] Rotary kiln flue gas A is the flue gas produced by fuel combustion in the rotary kiln. The temperature is generally 900-1150°C, the oxygen content is generally within 5%, and the NOx concentration in the flue gas is generally 800-1500ppm. The flue gas A of the rotary kiln moves upwards into the kiln gas flue 21 after passing through the kiln tail smoke chamber 6, and enters the calciner cone 11 through the furnace inlet 22 of the kiln ...

Embodiment 2

[0069] The difference from Embodiment 1 is that the calciner cylinder 12 is provided with a narrowing 13 in the middle of the calciner.

[0070] see Figure 5 . Preferably, the calciner column 12 is provided with a calciner middle neck 13 . The shrinkage 13 in the middle of the calciner is located below the upper feeding point 52 of the raw meal of the calciner. The raw meal that enters from the feed point 52 on the raw meal of the calciner moves downward under the action of gravity. By setting the neck 13 in the middle of the calciner, the cross-sectional wind speed at the neck becomes larger than that of the cylinder, which can effectively reduce the raw material. The falling height of the material can be adjusted to prevent material collapse in the calciner.

Embodiment 3

[0072] The difference from Embodiment 1 is that a column section 14 at the bottom of the calciner is provided between the calciner cone 11 and the furnace inlet 32 ​​of the tertiary air pipe. The lower feed point 51 of the calciner raw meal and the calciner fuel feed point 41 located below the furnace inlet of the kiln gas flue are located on the column section 14 at the bottom of the calciner.

[0073] see Figure 6 . Preferably, a calciner bottom column section 14 is provided between the calciner cone 11 and the furnace inlet 32 ​​of the tertiary air duct. The tertiary air first passes through the column section 14 at the bottom of the calciner, and then enters the cone 11 of the calciner. At this time, the calciner fuel feed point 41 located below the inlet of the kiln gas flue and the lower feed point 51 of the calciner raw material are located on the column section 14 at the bottom of the calciner. The mixture of smoke and gas is more conducive to the ignition of fuel....

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Abstract

The invention discloses a self-denitrification system and process for combustion and self-denitration in the concentration and light oxygen-containing zones of a calciner. The side connection, the tertiary air pipe is connected to the bottom of the calciner cone, forming a horizontally partitioned combustion environment with a central oxygen-rich zone and a peripheral low-oxygen zone on the transverse section of the calciner; the kiln gas flue is a strong reduction zone, and the calciner is a combustion environment. In the ember zone, a vertically graded combustion environment with different oxygen peroxide coefficients is formed in the combined combustion space of the kiln gas flue and the calciner. The horizontal partition combustion environment is realized by making the tertiary air enter vertically upward from the center of the bottom of the calciner, and the flue gas enters the air from the side of the calciner by tangential rotation of the volute; the vertically graded combustion environment is realized by fuel graded feeding. The present invention realizes self-denitrification through zone-organized combustion as a whole, improves self-denitrification efficiency, does not reduce the combustion speed of calciner fuel and completely decomposes raw meal, and has no adverse effect on the cement clinker production process.

Description

technical field [0001] The invention relates to the technical field of denitrification of flue gas in the cement industry, in particular to a self-denitration system and process for combustion self-denitration in the concentration and light oxygen-containing zones of the calciner. 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 t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): F27D17/00F27D99/00
CPCF27D17/002F27D17/008F27D99/0001
Inventor 陈昌华彭学平胡芝娟陈廷伟林敏燕
Owner TIANJIN CEMENT IND DESIGN & RES INST
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