Advanced reburning self-denitration low-nitrogen decomposing furnace of cement kiln

Abstract

The utility model relates to application of a preheater system of a cement kiln, in particular to an advanced reburning self-denitration low-nitrogen decomposing furnace of a cement kiln, which comprises a decomposing furnace communicated above a smoke chamber, a scattering box communicated with the decomposing furnace and an air pipe, a first reduction area and a second reduction area are arranged in the decomposing furnace, the second reduction area is positioned at the upper part of the first reduction area, and the scattering box is positioned at the lower part of the second reduction area. The air pipe is located between the first reduction area and the second reduction area, and a plurality of combustors are evenly arranged on the decomposing furnace in the circumferential direction of the decomposing furnace and arranged in the first reduction area and the second reduction area respectively. According to the utility model, the process denitration capability of a cement kiln system can be effectively improved, and the background concentration of nitrogen oxides is reduced; meanwhile, more reasonable matching of air, coal and materials is more beneficial to sufficient combustion of pulverized coal of the decomposition furnace, and the decomposition rate of the materials is increased.

Description

Technical Field

[0001] The utility model belongs to the application of cement kiln preheater system, specifically an advanced reburning self-denitrification low-nitrogen decomposition furnace for cement kiln. Background Art

[0002] Cement kilns produce a large amount of nitrogen oxides during use. The production of nitrogen oxides makes the exhaust gas fail to meet national standards. In order to make the exhaust gas meet national standards, most of the existing cement kiln preheaters have completed staged combustion transformation.

[0003] After the staged combustion modification, pulverized coal is delivered to the precalciner by a burner for primary reduction with the flue gas, resulting in a moderate reduction in the background concentration of nitrogen oxides. However, as the reduced flue gas continues to move upward through the cement kiln, some nitrogen oxides are still produced. Although this nitrogen oxide content is relatively low, cement companies are forced to further reduce it by increasing ammonia dosage or adding end-of-pipe SCR treatment to meet regulatory requirements. This process, whether through increased ammonia or SCR, increases operating costs, presenting new challenges and challenges for cement companies. Utility Model Content

[0004] The utility model provides an advanced reburning self-denitrification low-nitrogen decomposition furnace for a cement kiln, which is used to solve the defects in the prior art.

[0005] The utility model is achieved through the following technical solutions:

[0006] A cement kiln advanced reburning self-denitrification low-nitrogen decomposition furnace includes a decomposition furnace connected above a smoke chamber, a spreading box and an air duct connected to the decomposition furnace. A first reduction zone and a second reduction zone are provided in the decomposition furnace. The second reduction zone is located at the lower part of the decomposition furnace and above the first reduction zone. The air duct is located between the first reduction zone and the second reduction zone. The decomposition furnace is evenly provided with several burners along its circumference, and the burners are respectively arranged in the first reduction zone and the second reduction zone.

[0007] When the present application is in use, the flue gas flows from bottom to top in the decomposition furnace, and the pulverized coal enters the decomposition furnace through the burner. When the flue gas passes through the first reduction zone, the flue gas and the pulverized coal undergo a first reduction reaction, so that the concentration of nitrogen oxides in the flue gas is reduced to a certain extent. As the flue gas moves upward, the nitrogen oxides generated again undergo a second reduction reaction with the pulverized coal in the second reduction zone, and the nitrogen oxide concentration is further consumed. As the flue gas continues to move upward, the flue gas temperature decreases and no more nitrogen oxides are generated, thereby reducing the overall concentration of nitrogen oxides.

[0008] Preferably, the air duct is connected to the first air inlet of the decomposition furnace, one end of the air duct is connected upwardly to a denitrification pipe, the other end of the denitrification pipe is bent and connected to the second air inlet of the decomposition furnace, and the second reduction zone is located between the first and second air inlets in height. Control valves are provided on both the air duct and the denitrification pipe. The denitrification pipe can serve to divide the air, thereby reducing the oxygen concentration in the area between the first and second air inlets, providing low-oxygen conditions for better reduction in the second reduction zone.

[0009] Preferably, there are two spreading boxes, which are respectively arranged on both sides of the upper part of the decomposition furnace and are both connected to the corresponding sides of the decomposition furnace. There are two spreading boxes to ensure that the material entering the decomposition furnace is more uniform, thereby achieving a better reduction reaction with the flue gas.

[0010] Preferably, the decomposition furnace is provided with a first feed inlet, a second feed inlet, and a third feed inlet on both sides from top to bottom, and a material distribution valve is provided at the material distribution box outlet. The first feed inlet, the second feed inlet, and the third feed inlet are respectively connected to the valve openings corresponding to the material distribution valves through a feed pipe. The first feed inlet is located above the second air inlet, the second feed inlet is located between the second reduction zone and the second air inlet, and the third feed inlet is located between the first air inlet and the first reduction zone. The materials enter the decomposition furnace through the first feed inlet, the second feed inlet, and the third feed inlet, respectively, which can achieve the dispersion of the materials, thereby enabling the upward flue gas to better lift the materials and prevent the materials from excessively suppressing the flue gas.

[0011] Preferably, the burners are evenly distributed around the decomposition furnace, which can ensure that the pulverized coal is more evenly arranged around the burners, thereby achieving a more complete reaction of the pulverized coal.

[0012] The beneficial effects of this utility model include: it effectively improves the denitrification capacity of the cement kiln system and reduces the background concentration of nitrogen oxides. Furthermore, the more rational combination of air, coal, and materials facilitates the full combustion of pulverized coal in the decomposition furnace, improving the decomposition rate of the materials. This device further reduces the background concentration of nitrogen oxides in the cement kiln, achieving a background concentration of nitrogen oxides at the kiln outlet (assuming no denitrification reducing agent is used) below 200 mg / Nm³. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0014] Figure 1 It is a structural diagram of the utility model;

[0015] As shown in the figure:

[0016] 1. Decomposition furnace, 2. First reduction zone, 3. Second reduction zone, 4. Smoke chamber, 5. Air duct, 6. Denitrification pipe, 7. Spreading box, 8. Burner, 9. First feed port, 10. Second feed port, 11. Third feed port. DETAILED DESCRIPTION

[0017] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0018] An advanced reburning self-denitrification low nitrogen decomposition furnace for cement kilns, such as Figure 1 As shown. It includes a decomposition furnace 1 connected to the top of the smoke chamber 4, a material spreading box 7 and an air duct 5 connected to the decomposition furnace 1. The decomposition furnace 1 is provided with a first reduction zone 2 and a second reduction zone 3. The second reduction zone 3 is located above the first reduction zone 2 and the second reduction zone 3 is located at the bottom of the decomposition furnace. The air duct 5 is located between the first reduction zone 2 and the second reduction zone 3. The decomposition furnace 1 is evenly provided with a plurality of burners 8 along its circumference. The burners 8 are respectively provided in the first reduction zone 2 and the second reduction zone 3.

[0019] When the present application is in use, the flue gas flows from bottom to top in the decomposition furnace 1, and the pulverized coal enters the decomposition furnace 1 through the burner 8. When the flue gas passes through the first reduction zone 2, the flue gas and the pulverized coal undergo a first reduction reaction, so that the concentration of nitrogen oxides in the flue gas is reduced to a certain extent. As the flue gas moves upward, the nitrogen oxides produced again undergo a second reduction reaction with the pulverized coal in the second reduction zone 3, and the concentration of nitrogen oxides is further consumed. As the flue gas continues to move upward, the flue gas temperature decreases and no more nitrogen oxides are produced, thereby reducing the overall concentration of nitrogen oxides.

[0020] An air duct 5 is connected to the first air inlet of the decomposition furnace 1. One end of the air duct 5 is connected upward to a denitrification pipe 6. The other end of the denitrification pipe 6 is bent and connected to the second air inlet of the decomposition furnace 1. The second reduction zone 3 is located between the first and second air inlets. Control valves are installed on both the air duct 5 and the denitrification pipe 6. The denitrification pipe 6 acts as an air separator, thereby reducing the oxygen concentration in the area between the first and second air inlets, providing low-oxygen conditions for better reduction in the second reduction zone 3.

[0021] There are two spreading boxes 7, which are respectively arranged on both sides of the upper part of the decomposition furnace 1 and are communicated with the corresponding sides of the decomposition furnace 1. The first feed port 9, the second feed port 10 and the third feed port 11 are provided on both sides of the decomposition furnace 1 from top to bottom. The discharge port of the spreading box 7 is provided with a dividing valve. The first feed port 9, the second feed port 10 and the third feed port 11 are respectively communicated with the valve ports corresponding to the dividing valves through the discharge pipes. The first feed port 9 is located above the second air inlet, the second feed port 10 is located between the second reduction zone 3 and the second air inlet, and the third feed port 11 is located between the first air inlet and the first reduction zone 2.

[0022] The two spreading boxes 7 can ensure that the materials entering the decomposition furnace 1 are more uniform, thereby achieving a better reduction reaction with the flue gas. The materials enter the decomposition furnace 1 through the first feed port 9, the second feed port 10 and the third feed port 11 respectively, which can achieve the purpose of dispersing the materials, thereby enabling the upward flue gas to better lift the materials and prevent the materials from suppressing the flue gas.

[0023] The burners 8 are evenly distributed around the calciner 1, which can ensure that the pulverized coal is more evenly arranged around the burners 8, thereby achieving a more complete reaction of the pulverized coal.

[0024] This utility model can effectively improve the denitrification capacity of the cement kiln system and reduce the background concentration of nitrogen oxides. At the same time, the more reasonable combination of air, coal and materials is more conducive to the full combustion of coal powder in the decomposition furnace 1, thereby improving the decomposition rate of materials. This device further reduces the background concentration of nitrogen oxides in the cement kiln and can achieve a background concentration of nitrogen oxides at the kiln tail (without using a denitrification reducing agent) of 200mg / Nm 3 the following.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An advanced reburning self-denitrification low-nitrogen decomposition furnace for cement kilns, characterized by: It includes a decomposition furnace connected to the top of the smoke chamber, a spreading box and an air duct connected to the decomposition furnace. The decomposition furnace is provided with a first reduction zone and a second reduction zone. The second reduction zone is located at the lower part of the decomposition furnace and above the first reduction zone. The air duct is located between the first reduction zone and the second reduction zone. The decomposition furnace is evenly provided with several burners along its circumference, and the burners are respectively arranged in the first reduction zone and the second reduction zone.

2. The cement kiln advanced reburning self-denitrification low-nitrogen decomposition furnace according to claim 1 is characterized by: The air duct is connected to the first air inlet of the decomposition furnace. The air duct is upwardly connected to one end of the denitrification pipe. The other end of the denitrification pipe is bent and connected to the second air inlet of the decomposition furnace. The second reduction zone is located between the first air inlet and the second air inlet in height. Control valves are provided on both the air duct and the denitrification pipe.

3. The cement kiln advanced reburning self-denitrification low-nitrogen decomposition furnace according to claim 1 is characterized by: There are two material spreading boxes, which are respectively arranged on both sides of the upper part of the decomposition furnace and are both communicated with the corresponding sides of the decomposition furnace.

4. The cement kiln advanced reburning self-denitrification low-nitrogen decomposition furnace according to claim 3 is characterized by: A first feed port, a second feed port and a third feed port are provided on both sides of the decomposition furnace from top to bottom, and a distribution valve is provided at the discharge port of the spreading box. The first feed port, the second feed port and the third feed port are respectively connected to the valve ports corresponding to the distribution valves through the discharge pipes. The first feed port is located above the second air inlet, the second feed port is located between the second reduction zone and the second air inlet, and the third feed port is located between the first air inlet and the first reduction zone.

5. The cement kiln advanced reburning self-denitrification low-nitrogen decomposition furnace according to claim 1 is characterized by: The burners are evenly distributed around the decomposition furnace.

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