Ammonia gas spraying device of heating furnace

Abstract

The utility model relates to the technical field of industrial flue gas denitration equipment, in particular to a heating furnace ammonia gas spraying device which comprises a core pipe and an outer pipe, and the outer pipe sequentially comprises a rear pipe, a middle pipe and a front pipe in the gas flowing direction. The rear pipe is coaxially sleeved on the core pipe, the rear pipe is communicated with the ammonia gas inlet pipe, and the core pipe is communicated with the air inlet pipe; an annular flow guide protrusion is arranged in the middle of the inner surface of the middle pipe, and the diameter of the middle pipe is gradually decreased and then gradually increased through the flow guide protrusion. The ammonia gas spraying device of the heating furnace has the advantages that ammonia gas is used as a raw material, and due to the fact that a steel mill is provided with an ammonia gas station, the problems of storage and transportation are solved, and using difficulty and cost are reduced. Furthermore, according to the ammonia gas injection device of the heating furnace, a flow guide bulge is arranged on the middle pipe, so that the ammonia gas and the air form rotational flow, and the ammonia gas and the air are mixed more sufficiently, thereby improving the denitration efficiency.

Description

Technical Field

[0001] This utility model relates to the technical field of industrial flue gas denitrification equipment, and in particular to an ammonia injection device for a heating furnace. Background Technology

[0002] Nitrogen oxides (NOx) have become one of the major pollutants causing air pollution. NOx in the flue gas of heating furnaces is a key source of pollution in hot rolling mills. The mainstream flue gas denitrification processes are SNCR and SCR. Some heating furnaces have gradually started to use the SCR process. However, this process requires the addition of auxiliary equipment such as forced exhaust devices and catalysts, which involves huge investment and requires continuous maintenance of catalyst consumption and equipment power consumption.

[0003] SNCR technology requires less investment and has a simpler equipment structure, but existing SNCR denitrification technologies have the following problems: Most use ammonia water, which is easier to store and transport, but ammonia water injection efficiency is low: uneven atomization leads to large fluctuations in denitrification rate (60%~80%), and ammonia slip rate >8ppm; the spray gun is easily damaged: the single-channel structure has poor high-temperature resistance, and its lifespan is less than 6 months at high furnace temperatures (>1000℃). If ammonia gas is used, ammonia and air are not easily mixed evenly, resulting in low denitrification efficiency. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide an ammonia injection device for a heating furnace with high denitrification efficiency.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: a heating furnace ammonia injection device is provided, including a core tube and an outer tube. The outer tube includes a rear tube, a middle tube and a front tube in sequence along the gas flow direction. The rear tube is coaxially sleeved on the core tube. The rear tube is connected to the ammonia inlet pipe, and the core tube is connected to the air inlet pipe.

[0006] The inner surface of the tube is provided with an annular flow-guiding protrusion, which causes the diameter of the tube to gradually decrease and then gradually increase.

[0007] The beneficial effects of this utility model are as follows: In the ammonia injection device for the heating furnace of this utility model, ammonia is used as the raw material. Since the steel plant itself has an ammonia station, storage and transportation problems are avoided, reducing the difficulty and cost of use. Furthermore, in the ammonia injection device for the heating furnace of this utility model, by setting a guide protrusion in the middle tube, the ammonia and air form a swirling flow, making the ammonia and air mix more thoroughly, thereby improving the denitrification efficiency. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the structure of an ammonia injection device for a heating furnace according to a specific embodiment of the present invention;

[0009] Label Explanation:

[0010] 1. Core tube; 11. Air inlet tube; 2. Outer tube; 21. Rear tube; 211. Ammonia inlet tube; 22. Middle tube; 23. Front tube; 24. Guide protrusion; 3. Silicon carbide ceramic nozzle; 4. Protective sleeve. Detailed Implementation

[0011] To explain in detail the technical content, objectives, and effects of this utility model, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0012] This utility model provides an ammonia injection device for a heating furnace, including a core tube and an outer tube. The outer tube includes a rear tube, a middle tube, and a front tube in sequence along the gas flow direction. The rear tube is coaxially sleeved on the core tube and is connected to the ammonia inlet pipe. The core tube is connected to the air inlet pipe.

[0013] The inner surface of the tube has an annular flow-guiding protrusion in the middle, which causes the diameter of the tube to gradually decrease and then gradually increase.

[0014] The beneficial effects of this utility model are as follows: In the ammonia injection device for the heating furnace of this utility model, ammonia is used as the raw material. Since the steel plant itself has an ammonia station, storage and transportation problems are avoided, reducing the difficulty and cost of use. Furthermore, in the ammonia injection device for the heating furnace of this utility model, by setting a guide protrusion in the middle tube, the ammonia and air form a swirling flow, which makes the ammonia and air mix more thoroughly, thereby improving the denitrification efficiency.

[0015] Furthermore, the aforementioned ammonia injection device for the heating furnace also includes a protective sleeve, which is fitted onto the outer pipe.

[0016] As described above, installing a protective sleeve can protect the outer tube and prevent high-temperature erosion.

[0017] Furthermore, in the aforementioned ammonia injection device for the heating furnace, nitrogen is provided inside the protective sleeve.

[0018] Furthermore, in the aforementioned ammonia injection device for the heating furnace, the flow rate of nitrogen in the protective sleeve is 0.5 m³ / h.

[0019] As described above, nitrogen gas (flow rate 0.5 m³ / h) is introduced to prevent high-temperature ablation.

[0020] Furthermore, in the aforementioned ammonia injection device for the heating furnace, the angle between the guide surface formed by the guide protrusion and the horizontal plane is 30 degrees.

[0021] As described above, the guide protrusion forms a 30-degree spiral guide vane, which can create a swirling flow of 15~20m / s, making the ammonia and air mix more thoroughly.

[0022] Furthermore, in the aforementioned ammonia injection device for the heating furnace, the flow rate ratio of ammonia in the rear tube to air in the core tube is 1:1.2-1.5.

[0023] As described above, ammonia consumption can be reduced by more than 30% by optimizing the flow ratio (1:1.2~1:1.5).

[0024] Furthermore, in the aforementioned ammonia injection device for the heating furnace, the end of the front pipe is provided with a silicon carbide ceramic nozzle.

[0025] As described above, the front end is connected to a silicon carbide ceramic nozzle, which is resistant to 1200℃, protecting the front tube from high-temperature erosion.

[0026] Furthermore, in the aforementioned ammonia injection device for the heating furnace, the rear pipe is made of 316L stainless steel and has a wall thickness of 2mm.

[0027] Furthermore, in the aforementioned ammonia injection device for the heating furnace, the guide protrusion is made of Inconel 600.

[0028] As described above, the material configuration makes the guide protrusion corrosion-resistant, sturdy, and durable.

[0029] Furthermore, in the aforementioned ammonia injection device for the heating furnace, an electric heating wire is wound around the surface of the ammonia inlet pipe.

[0030] As described above, an electric heating wire is wound around the pipe to maintain the pipe temperature at 60±5℃ and prevent ammonia crystallization.

[0031] Example 1

[0032] Please refer to Figure 1 As shown, an ammonia injection device for a heating furnace includes a core tube 1 and an outer tube 2. The outer tube 2 includes a rear tube 21, a middle tube 22 and a front tube 23 in sequence along the gas flow direction. The rear tube 21 is coaxially sleeved on the core tube 1 and is connected to an ammonia inlet pipe 211. The core tube 1 is connected to an air inlet pipe 11.

[0033] The inner surface of the central tube 22 is provided with an annular flow guiding protrusion 24, which causes the diameter of the central tube 22 to gradually decrease and then gradually increase.

[0034] It also includes a protective sleeve 4, which is fitted onto the outer pipe 2. The protective sleeve 4 contains nitrogen gas. The flow rate of the nitrogen gas in the protective sleeve 4 is 0.5 m³ / h.

[0035] The angle between the guide surface formed by the guide protrusion 24 and the horizontal plane is 30 degrees. The guide protrusion 24 forms a 30-degree spiral guide vane, which can create a swirling flow of 15~20m / s, making the ammonia and air mix more thoroughly.

[0036] The flow rate ratio of ammonia in the rear tube 21 to air in the core tube 1 is 1:1.2-1.5. A silicon carbide ceramic nozzle 3 is provided at the end of the front tube 23. The rear tube 21 is made of 316L stainless steel and has a wall thickness of 2mm. The guide protrusion 24 is made of Inconel 600.

[0037] The aforementioned ammonia injection device for the heating furnace is applied in a 1780mm hot continuous rolling heating furnace:

[0038] Spray gun arrangement: 18 spray guns are installed in three zones along the length of the furnace, with a spacing of 1.2m and a spray angle of 15°.

[0039] Parameter settings:

[0040] Ammonia pressure: 0.35 MPa, compressed air pressure: 0.42 MPa (flow ratio 1:1.3).

[0041] Spray atomization particle size: ≤50μm (detected by laser particle size analyzer);

[0042] Running result:

[0043] Denitrification efficiency: 88%~92% (NOx emission concentration ≤45mg / Nm³);

[0044] Ammonia slip rate: <1.8 ppm;

[0045] Spray gun life: ≥18 months (continuous operation without clogging).

[0046] Cost advantages: 70% lower investment compared to SCR technology, and 35% lower ammonia consumption compared to traditional SNCR (using ammonia water);

[0047] Safety: Ammonia slip rate <2ppm, meeting GB13223-2011 ultra-low emission standards.

[0048] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent modifications made based on the content of this utility model specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A heating furnace ammonia injection device characterized by, It comprises a core pipe and an outer pipe, the outer pipe comprises a rear pipe, a middle pipe and a front pipe in sequence along the gas flow direction; the rear pipe is coaxially sleeved on the core pipe, the rear pipe is communicated with an ammonia inlet pipe, and the core pipe is communicated with an air inlet pipe; A ring-shaped flow guide protrusion is arranged in the middle part of the inner surface of the middle pipe, and the flow guide protrusion makes the diameter of the middle pipe gradually decrease and then gradually increase.

2. The ammonia injection device for a heating furnace according to claim 1, wherein It further comprises a protective sleeve, the protective sleeve is sleeved on the outer pipe.

3. The ammonia injection device for a heating furnace according to claim 2, wherein Nitrogen is arranged in the protective sleeve.

4. The ammonia injection device for a heating furnace according to claim 3, wherein The flow rate of the nitrogen in the protective sleeve is 0.5m³ / h.

5. The ammonia injection device for a heating furnace according to claim 1, wherein The included angle between the flow guide surface formed by the flow guide protrusion and the horizontal plane is 30 degrees.

6. The ammonia injection device for a heating furnace according to claim 1, wherein The flow rate ratio of the ammonia in the rear pipe to the air in the core pipe is 1:1.2-1.

5.

7. The ammonia injection device for a heating furnace according to claim 1, wherein The front pipe is provided with a silicon carbide ceramic nozzle at the end.

8. The ammonia injection device for a heating furnace according to claim 1, wherein The material of the rear pipe is a 316L stainless steel pipe, and the wall thickness of the rear pipe is 2mm.

9. The ammonia injection device for a heating furnace according to claim 1, wherein The material of the flow guide protrusion is Inconel 600.

10. The ammonia injection device for a heating furnace according to claim 1, wherein An electric heating wire is wound on the surface of the ammonia inlet pipe.

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