High-temperature calcining kiln with denitrification device and denitrification method

Abstract

The high-temperature calcining kiln with the denitrification device comprises a kiln body, the kiln body is sequentially divided into a cooling section, a sintering section, a decomposition section, a preheating section and a drying section from a discharging end to a feeding end according to the temperature distribution condition during working of the calcining kiln, the decomposition section is provided with an ammonia steam introducing device, the ammonia steam introducing device comprises a plurality of vent holes formed in the kiln wall, and the vent holes are communicated with the cooling section. A circle of annular steam cover is arranged on the outer sides of the vent holes, a circle of annular sealing area is formed between the annular steam cover and the outer wall of the kiln body, the outer ends of all the vent holes are communicated with the annular sealing area, the annular steam cover is provided with a steam inlet, and the outside of the steam inlet is connected to an ammonia steam source; the ammonia steam is sprayed into the proper position of the high-temperature calcining kiln, so that the flue gas is subjected to denitrification treatment in the kiln body of the high-temperature calcining kiln, and the flue gas discharged from the kiln does not need to be treated by a special denitrification device; and the tail gas does not need to be heated, so that a large amount of energy consumption is saved, energy conservation and emission reduction are facilitated, and great economic benefits are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of calcining kilns, in particular to a high-temperature calcining kiln with a denitrification device and a denitrification method. Background Art

[0002] The calcining kiln is a kind of kiln commonly used in industry. It rotates continuously during operation, and the materials in the kiln are evenly heated. The flue gas generated by some materials during the heating process contains NOx, and the flue gas needs to be denitrified. There are currently two main denitrification treatment methods: one is to collect the flue gas in the kiln and then treat it in a special denitrification device. The basic principle of denitrification is that ammonia reacts with flue gas under high temperature. Ammonia (NH3) reacts with nitrogen oxides (NOx) to convert harmful nitrogen oxides into harmless nitrogen (N2) and water (H2O) to achieve denitrification. Therefore, the temperature needs to be lowered below 1 The exhaust gas from 100℃ is heated to above 200℃, and the energy consumption required for heating the exhaust gas is very large; it increases the equipment investment and prolongs the entire production process; the other method is to spray atomized ammonia water at the kiln head to make ammonia directly react with the flue gas in the kiln for denitrification. However, in actual production, this treatment method can only be applied to low-temperature calcining kilns with a kiln temperature below 1000℃. For high-temperature calcining kilns with a maximum temperature of 1500℃, it is impossible to effectively denitrify. The reason is that the nitrogen produced after the ammonia denitrification reaction in the kiln combines with oxygen to form NOx in a high temperature environment of about 1500℃, resulting in denitrification failure. Summary of the invention

[0003] The purpose of the present invention is to solve the technical problems existing in the denitrification of a high-temperature calcining kiln and to provide a high-temperature calcining kiln with a denitrification device and a denitrification method.

[0004] The specific scheme of the present invention is: a high-temperature calcining kiln with a denitrification device comprises a kiln body, one end of the kiln body is provided with a feed port, the other end of the kiln body is provided with a discharge port, a burner is installed at one end of the kiln body located at the discharge port, and the kiln body is divided into a cooling section, a firing section, a decomposition section, a preheating section, and a drying section from the discharge end to the feed end according to the temperature distribution when the calcining kiln is working, wherein the decomposition section is provided with an ammonia steam introduction device, the ammonia steam introduction device comprises a plurality of vents arranged on the kiln wall, the inner ends of the vents are connected to the inside of the kiln body, a circle of annular steam hoods are provided on the outside of the vents, a circle of annular sealing areas are formed between the annular steam hoods and the outer wall of the kiln body, the outer ends of all the vents are connected to the annular sealing areas, the annular steam hoods are provided with a steam inlet, and the outside of the steam inlet is connected to an ammonia steam source.

[0005] Furthermore, an angle β is provided between the vent hole and the radial center line of the kiln body, and the angle β makes the injection direction of the ammonia vapor into the kiln through the vent hole opposite to the rotation direction of the kiln body.

[0006] Furthermore, the range of β is 30°-50°.

[0007] Furthermore, a sealing ring is provided on each side of the annular steam hood on the outer wall of the kiln body, the root of the sealing ring is fixedly connected to the kiln body, and the annular steam hood and the sealing ring are slidably connected to form a dynamic seal.

[0008] Furthermore, a wear-resistant sheet is installed between the sealing ring and the annular steam cover.

[0009] Furthermore, a circle of reinforcing plates is arranged between the sealing ring and the kiln body, the reinforcing plates are welded to the outer wall of the kiln body, the sealing ring is fixedly connected to the reinforcing plates, and through holes are arranged on the reinforcing plates corresponding to the respective vents.

[0010] Furthermore, a nozzle is provided in the vent hole, and the nozzle is arranged along the entire length of the vent hole.

[0011] The present invention also provides a high-temperature calcining kiln denitrification method, which uses the above-mentioned calcining kiln and includes the following steps: S1. When the calcining kiln reaches a stable working state after pneumatic operation, the temperature of the cooling section is about 900-1050°C, the temperature of the sintering section is about 1350-1550°C, the temperature of the decomposition section is about 750-950°C, the temperature of the preheating section is about 600-750°C, and the temperature of the drying section is about 350-500°C. At this time, ammonia steam is introduced into the annular steam hood; S2, ammonia vapor is sprayed into the kiln from each vent hole, and fully mixed with the flue gas in the decomposition section of the kiln to form a turbulent state; S3, ammonia vapor reacts chemically with the flue gas at 750-950℃ in the decomposition section to achieve denitrification; S4. The mixed flue gas after the reaction flows toward the feeding end of the kiln body and is discharged from the kiln body.

[0012] Furthermore, the temperature of the introduced ammonia vapor is 140-200° C. and the pressure is 0.3-0.6 MPa.

[0013] The present invention has the following beneficial effects: 1. By spraying ammonia vapor at a suitable position of the high-temperature calcining kiln, the flue gas can be denitrified in the kiln body of the high-temperature calcining kiln, and the flue gas discharged from the kiln does not need to be treated by a special denitrification device, thereby reducing the direct investment in environmental protection equipment; there is no need to heat the tail gas, thereby saving a large amount of energy consumption, being beneficial to energy conservation and emission reduction, and having great economic benefits; 2. The heat absorption of atomized ammonia water in the kiln is more than 55 times that of ammonia vapor. Therefore, the present invention adopts a method of spraying ammonia vapor, thereby reducing the negative impact on the temperature and atmosphere in the kiln. At the same time, the present invention eliminates the need for ammonia water atomization equipment, thereby saving corresponding costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1It is a schematic diagram of the structure of the present invention; Figure 2 yes Figure 1 Enlarged view at the middle V; Figure 3 yes Figure 2 AA view; Figure 4 Schematic diagram of the distribution of vent holes of the present invention; In the figure: 1, kiln body; 101, kiln wall plate; 102, refractory layer; 2, burner; 3, discharge port; 4, inlet; 5, annular steam hood; 6, wear-resistant sheet; 7, sealing ring; 8, reinforcement plate; 9, vent hole; 10, nozzle; 11, material. DETAILED DESCRIPTION

[0015] See also Figure 1-4The present embodiment is a high-temperature calcining kiln with a denitrification device, comprising a kiln body 1, a kiln wall plate 101 is provided on the outer wall of the kiln body 1, a refractory layer 102 is provided on the inner circle of the kiln wall plate 101, a feed port 4 is provided at one end of the kiln body 1, and a discharge port 3 is provided at the other end, a burner 2 is installed at one end of the kiln body 1 located at the discharge port 3, and the kiln body 1 is divided into a cooling section, a firing section, a decomposition section, a preheating section, and a drying section from the discharge end to the feed end according to the temperature distribution during operation of the calcining kiln, wherein the decomposition section is provided with an ammonia steam introduction device, the ammonia steam introduction device comprises a plurality of vents 9 arranged on the kiln wall, the inner ends of the vents 9 are connected with the inside of the kiln body 1, a circle of annular steam hoods 5 are provided on the outer sides of the vents 9, a circle of annular sealing areas are formed between the annular steam hoods 5 and the outer wall of the kiln body 1, the outer ends of all the vents 9 are connected with the annular sealing areas, the annular steam hoods 5 are provided with a steam inlet, and the steam inlet is externally connected to an ammonia steam source. Further, an angle β is provided between the vent hole 9 and the radial center line of the kiln body 1, and the angle β makes the injection direction of the ammonia vapor into the kiln through the vent hole 9 opposite to the rotation direction of the kiln body 1. Further, the range of β is 30°-50°. Further, a sealing ring 7 is provided on each side of the annular steam hood 5 on the outer wall of the kiln body 1, and the root of the sealing ring 7 is fixedly connected to the kiln body 1, and the annular steam hood 5 and the sealing ring 7 are slidably connected to form a dynamic seal. Further, a wear-resistant plate 6 is installed between the sealing ring 7 and the annular steam hood 5. Further, a circle of reinforcing plates 8 is provided between the sealing ring 7 and the kiln body 1, and the reinforcing plates 8 are welded to the outer wall of the kiln body 1, and the sealing ring 7 is fixedly connected to the reinforcing plates 8, and through holes are provided on the reinforcing plates 8 corresponding to each vent hole 9. Further, a nozzle 10 is provided in the vent hole 9, and the nozzle 10 is arranged along the entire length of the vent hole 9. The present invention also provides a high-temperature calcining kiln denitrification method, which uses the above-mentioned calcining kiln and includes the following steps: S1, when the calcining kiln reaches a stable working state after pneumatic operation, the temperature of the cooling section is about 900-1050°C, the temperature of the firing section is about 1350-1550°C, the temperature of the decomposition section is about 750-950°C, the temperature of the preheating section is about 600-750°C, and the temperature of the drying section is about 350-500°C. At this time, ammonia steam with a temperature of 140-200°C and a pressure of 0.3-0.6 MPa is introduced into the annular steam hood 5; S2, ammonia steam is sprayed into the kiln body 1 from each vent 9, and is fully mixed with the flue gas in the decomposition section in the kiln to form a turbulent state; S3, ammonia steam and the flue gas of 750-950°C in the decomposition section undergo a chemical reaction to achieve denitrification; S4, the mixed flue gas after the reaction flows to the feed end of the kiln body 1 and is discharged from the kiln body 1.The working principle of the present invention is as follows: according to the temperature distribution of each area in the kiln body 1 when the calcining kiln is working, it can be divided into a cooling section with a temperature of about 900-1050°C, a sintering section with a temperature of about 1350-1550°C, a decomposition section with a temperature of about 750-950°C, a preheating section with a temperature of about 600-750°C, and a drying section with a temperature of about 350-500°C; the material 11 in the kiln flows from the feed port 4 to the discharge port 3, and the flue gas flows from the discharge end to the feed end. The present invention selects to spray ammonia vapor into the decomposition section, It is fully mixed with the flue gas at 750-950℃ to produce a chemical reaction of denitrification, and then the mixed flue gas continues to flow to the feed end and is finally discharged from the kiln body 1; while when ammonia vapor is sprayed in other areas, the denitrification effect is not good. The specific reasons are as follows: if ammonia vapor is sprayed in the cooling section or the firing section, the nitrogen produced after the denitrification reaction will combine with oxygen in a high temperature environment of about 1500℃ to produce a large amount of thermal nitrogen NOx, resulting in denitrification failure; if ammonia vapor is sprayed in the preheating section or the drying section, the reaction temperature is not enough, resulting in poor denitrification effect. When the calcining kiln is working, the kiln body 1 rotates with the sealing ring 7, while the annular steam hood 5 is stationary. An annular sealing area is formed between the annular steam hood 5 and the sealing rings 7 on both sides and the kiln wall plate 101. An ammonia inlet is set at a certain position of the annular steam hood 5, so that ammonia vapor is continuously introduced into the kiln when the kiln is working. The ammonia vapor first enters the annular sealing area, and then is sprayed into the kiln through each vent 9. By arranging the nozzle 10 at an angle of 30°-50° with the center line, a swirl is generated when the ammonia vapor enters the kiln, which is conducive to the rapid and full mixing of the ammonia vapor with the flue gas in the decomposition section to accelerate the reaction speed, thereby achieving efficient denitrification and ensuring that the exhaust gas does not contain NOx. When the kiln is working, the material 11 is mainly distributed in the following areas. Figure 4 In the area shown, setting the vent hole 9 at this angle can effectively prevent the material 11 from leaking out of the vent hole 9.

Claims

1. A high-temperature calcining kiln with a denitrification device, comprising a kiln body, a material inlet at one end of the kiln body, a material outlet at the other end, and a burner at one end of the kiln body located at the material outlet, characterized in that: According to the temperature distribution when the calcining kiln is working, it is divided into cooling section, sintering section, decomposition section, preheating section and drying section from the discharge end to the feed end, wherein the decomposition section is provided with an ammonia steam introduction device, the ammonia steam introduction device comprises a plurality of air vents arranged on the kiln wall, the inner ends of the air vents are connected with the inside of the kiln body, an annular steam hood is provided on the outer side of the air vents, an annular sealing area is formed between the annular steam hood and the outer wall of the kiln body, the outer ends of all the air vents are connected with the annular sealing area, the annular steam hood is provided with a steam inlet, and the outside of the steam inlet is connected to an ammonia steam source.

2. The high temperature calcining kiln with a denitrification device according to claim 1, characterized in that: An angle β is provided between the vent hole and the radial center line of the kiln body, and the angle β makes the injection direction of ammonia vapor into the kiln through the vent hole opposite to the rotation direction of the kiln body.

3. The high temperature calcining kiln with a denitrification device according to claim 2, characterized in that: The range of β is 30°-50°.

4. The high temperature calcining kiln with a denitrification device according to claim 1, characterized in that: The outer wall of the kiln body is located on both sides of the annular steam hood and each sealing ring is provided with a sealing ring, the root of the sealing ring is fixedly connected to the kiln body, and the annular steam hood and the sealing ring are slidably connected to form a dynamic seal.

5. The high temperature calcining kiln with a denitrification device according to claim 4, characterized in that: A wear-resistant sheet is arranged between the sealing ring and the annular steam cover.

6. The high temperature calcining kiln with a denitrification device according to claim 4, characterized in that: A circle of reinforcing plates is arranged between the sealing ring and the kiln body, the reinforcing plates are welded to the outer wall of the kiln body, the sealing ring is fixedly connected to the reinforcing plates, and through holes are arranged on the reinforcing plates corresponding to the ventilation holes.

7. The high temperature calcining kiln with a denitrification device according to claim 1, characterized in that: A nozzle is arranged in the vent hole and is arranged along the entire length of the vent hole.

8. A high temperature calcining kiln denitrification method, using the calcining kiln according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. When the calcining kiln reaches a stable working state after pneumatic operation, the temperature of the cooling section is about 900-1050°C, the temperature of the sintering section is about 1350-1550°C, the temperature of the decomposition section is about 750-950°C, the temperature of the preheating section is about 600-750°C, and the temperature of the drying section is about 350-500°C. At this time, ammonia steam is introduced into the annular steam hood; S2, ammonia vapor is sprayed into the kiln from each vent hole, and fully mixed with the flue gas in the decomposition section of the kiln to form a turbulent state; S3, ammonia vapor reacts chemically with the flue gas at 750-950℃ in the decomposition section to achieve denitrification; S4. The mixed flue gas after the reaction flows toward the feeding end of the kiln body and is discharged from the kiln body.

9. The high temperature calcining kiln denitrification method according to claim 8, characterized in that: The temperature of the introduced ammonia vapor is 140-200° C., and the pressure is 0.3-0.6 MPa.

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