Small-flow ammonia spraying device

Abstract

The utility model provides a small-flow ammonia spraying device, and aims to optimize the capacity of distributing and spraying ammonia gas and adapting to flue changes so as to realize an efficient, stable and economical denitration process. Ammonia gas is introduced into the distribution branch pipes from the source, and is conveyed to each diffusion type ammonia spraying nozzle after being precisely regulated and controlled by the flow distributor and the pressure compensator. Ammonia gas is sprayed into a flue at a preset angle and flow through the diffusion type ammonia spraying nozzle and impacts the conical end face of the firing pin to be diffused towards the periphery, and in the collision process, the speed and pressure of the ammonia gas can be changed, so that the mixing effect of the ammonia gas and flue gas is enhanced. Therefore, the ammonia gas and the flue gas can be ensured to reach an ideal mixing state even under the condition of small flow, the coverage range of the ammonia gas is enlarged through the firing pin structure, and the problem that the small-flow ammonia gas and the flue gas are not fully mixed is effectively solved.

Description

Technical Field

[0001] This application relates to the field of air pollutant control, and in particular to a device for low-flow ammonia injection. Background Technology

[0002] The need for denitrification in gas-fired boilers, pyrolysis furnaces, and kilns has been put on the agenda. Many pollution sources with small flue gas volumes or low initial NOx concentrations also require denitrification, and most of them lack the temperature window and residence time for SNCR denitrification processes, essentially requiring SCR denitrification. While meeting denitrification efficiency requirements, ammonia slip control is also very stringent, necessitating a mixing deviation of less than 5% between ammonia and flue gas.

[0003] The denitrification reducing agent is a mixture of ammonia, water vapor, and air, which are products of urea pyrolysis, or a mixture of ammonia, water vapor, and air obtained by evaporating ammonia water. Due to the small volume of flue gas and the low initial NOx concentration, the amount of ammonia used is also very small. If a conventional ammonia injection grid is used, the mixing effect of ammonia and flue gas will be unsatisfactory because its nozzle orifice diameter is very small.

[0004] To improve the mixing effect of ammonia / flue gas, a common practice is to increase the dilution air volume and add a mixer after ammonia injection. However, increasing the dilution air volume also has some drawbacks, such as increased energy consumption (i.e., increased electric heater power and compressed air consumption), increased O2 content at the emission port, and decreased denitrification temperature. Furthermore, there is the problem of insufficient mixing between small flow rates of ammonia and flue gas. Utility Model Content

[0005] This application provides a small-flow ammonia injection device to address the problems of increased energy consumption (i.e., increased electric heater power, increased compressed air consumption, increased O2 content at the emission port, decreased denitrification temperature, and insufficient mixing of small-flow ammonia with flue gas) when increasing the dilution air volume. The device includes a diffusion-type ammonia injection nozzle, a distribution branch pipe, and fixed accessories.

[0006] One end of the diffusion-type ammonia injection nozzle is fixed to the cylindrical surface of the distribution branch pipe and communicates with the distribution branch pipe. One end of the distribution branch pipe is fixed to and communicates with the flue through the fixing accessory.

[0007] The diffuser-type ammonia injection nozzle has a through hole, and the end of the diffuser-type ammonia injection nozzle away from the distribution branch pipe has a nozzle. A striker is provided at the edge of the nozzle, and the end of the striker away from the nozzle has a conical end face, which is opposite to the center of the nozzle.

[0008] In one feasible implementation, the diameter of the through hole ranges from Φ1mm to Φ6mm.

[0009] In one feasible implementation, the angle of the tapered end face of the firing pin is in the range of 60°-120°.

[0010] In one feasible implementation, there are multiple diffusion-type ammonia injection nozzles, which are evenly distributed on the distribution branch pipe.

[0011] In one feasible implementation, the jetting area of ​​the plurality of diffusion-type ammonia injection nozzles is larger than the flue area, and the arrangement of the diffusion-type ammonia injection nozzles includes frontal arrangement, side arrangement, and cross arrangement.

[0012] In one feasible implementation method

[0013] The front arrangement is as follows: multiple diffusion-type ammonia injection nozzles are arranged in the same direction on the distribution branch pipe, and the orientation of the diffusion-type ammonia injection nozzles is the same as the axial direction of the flue.

[0014] The side arrangement is as follows: multiple diffusion-type ammonia injection nozzles are arranged in the same direction on the distribution branch pipe, and the orientation of the diffusion-type ammonia injection nozzles intersects with the axial direction of the flue.

[0015] The cross arrangement is as follows: multiple diffusion-type ammonia injection nozzles are arranged alternately on the distribution branch pipe, with some facing the same axial direction as the flue and others facing a direction that crosses the axial direction of the flue.

[0016] In one feasible implementation, a flow distributor is provided inside the distribution branch pipe;

[0017] The flow distributor is fixed at the connection point between the diffusion-type ammonia injection nozzle and the distribution branch pipe, and the flow distributor is used to control the flow rate of ammonia gas entering the diffusion-type ammonia injection nozzle.

[0018] In one feasible implementation, a pressure compensator is also provided in the distribution branch pipe; the pressure compensator is located at the connection position between the distribution branch pipe and the fixed accessory, and the pressure compensator is used to control the stability of the ammonia flow rate and pressure in the distribution branch pipe.

[0019] In one feasible implementation, an elastic connector is provided between the distribution branch pipe and the fixed accessory, and the elastic connector is a rubber pad or a spring.

[0020] In one feasible implementation, a corrugated pipe is provided between the fixed accessory and the flue, and limiting devices are provided on both sides of the corrugated pipe. The limiting device has a fixed end and a limiting end. The fixed end is fixedly connected to the flue, and the limiting end extends toward a position away from the flue. The projection of the limiting end on the flue overlaps at least partially with the corrugated pipe.

[0021] The ammonia injection device for low-flow rates provided in this application optimizes the ammonia injection volume and diffusion pattern by precisely controlling the orifice diameter of the diffusion-type ammonia injection nozzle and the conical end face angle of the impact pin. This reduces unnecessary dilution air volume, thereby lowering the power of the electric heater and the consumption of compressed air. The optimized ammonia injection and diffusion method helps reduce ammonia escape and prevents excessive ammonia from entering the flue gas, thus controlling the increase in O2 content at the emission port and maintaining the stable operation of the denitrification system. The design of the diffusion-type ammonia injection nozzle allows the ammonia to be ejected in a hollow cone shape and fully mixed with the flue gas. Furthermore, by adjusting the arrangement and number of nozzles, the mixing effect can be further optimized, improving the denitrification efficiency. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the embodiments of the present invention. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0023] Figure 1 This is a schematic diagram of the structure of a small-flow ammonia injection device shown in an exemplary embodiment of this application;

[0024] Figure 2 yes Figure 1 A magnified view of a portion of the image.

[0025] Explanation of reference numerals in the attached figures

[0026] 10-Diffusion type ammonia injection nozzle; 20-Distribution branch pipe; 30-Fixing accessory; 11-Inlet; 12-Actuating pin. Detailed Implementation

[0027] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make the present invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of the implementation of embodiments of the present invention.

[0028] Existing SCR denitrification processes, while meeting denitrification efficiency requirements, also require very strict ammonia slip control, necessitating a mixing deviation of less than 5% between ammonia and flue gas. However, due to the small flue gas volume and low initial NOx concentration, the ammonia consumption is also very small. Using conventional ammonia injection grids, the very small nozzle orifice diameter leads to unsatisfactory ammonia-flue gas mixing. To improve ammonia / flue gas mixing, a common practice is to increase the dilution air volume and add a mixer after ammonia injection. However, increasing the dilution air volume has several drawbacks, such as increased energy consumption (increased electric heater power and compressed air consumption), increased O2 content at the emission port, and decreased denitrification temperature. Furthermore, there is the problem of insufficient mixing between small-flow ammonia and flue gas.

[0029] To address the aforementioned problems, this application provides an embodiment of a small-flow ammonia injection device, referring to... Figure 1 and Figure 2 As shown, it includes a diffusion-type ammonia injection nozzle 10, a distribution branch pipe 20, and a fixing accessory 30; one end of the diffusion-type ammonia injection nozzle 10 is fixed to the cylindrical surface of the distribution branch pipe 20 and communicates with the distribution branch pipe 20, and one end of the distribution branch pipe 20 is fixed to and communicates with the flue through the fixing accessory 30; the diffusion-type ammonia injection nozzle 10 is provided with a through hole, and the end of the diffusion-type ammonia injection nozzle 10 away from the distribution branch pipe 20 is provided with a nozzle 11, and a striking pin 12 is provided at the edge of the nozzle 11. The end of the striking pin 12 away from the nozzle 11 is provided with a conical end face, and the conical end face is opposite to the center position of the nozzle 11.

[0030] The device mainly comprises a diffusion-type ammonia injection nozzle 10, a distribution branch pipe 20, and a fixing accessory 30. First, the diffusion-type ammonia injection nozzle 10 serves as the ammonia outlet, with one end fixed to the cylindrical surface of the distribution branch pipe 20 and connected to the interior of the pipe, ensuring smooth ammonia flow. The distribution branch pipe 20 serves as the main pipeline for ammonia delivery, with one end tightly connected to the flue gas duct via the fixing accessory 30, achieving effective contact and mixing of ammonia and flue gas.

[0031] The diffuser-type ammonia nozzle 10 has an internal through-hole for the flow of ammonia gas. At the end of the nozzle furthest from the distribution branch pipe 20, there is a nozzle orifice 11, and a striking pin 12 is positioned at the edge of the nozzle orifice 11. The end of the striking pin 12 furthest from the nozzle orifice 11 has a conical end face, which is directly opposite the center of the nozzle orifice 11. When ammonia gas flows through the through-hole into the nozzle orifice 11, it collides with the conical end face of the striking pin 12 and is guided to diffuse outwards, forming a hollow cone-shaped spray pattern.

[0032] This design improves the coverage of ammonia gas and allows for more thorough mixing with the flue gas. During the collision process, the velocity and pressure of the ammonia gas change, thereby enhancing its mixing effect with the flue gas. Therefore, even at low flow rates, it ensures an ideal mixing state between ammonia gas and flue gas, effectively solving the problem of insufficient mixing of ammonia gas and flue gas at low flow rates.

[0033] Furthermore, by precisely controlling the orifice diameter of the diffusion-type ammonia injection nozzle 10 and the conical end face angle of the impact pin 12, the ammonia injection volume and diffusion pattern can be optimized. This not only reduces unnecessary dilution air volume, thereby reducing the power of the electric heater and the consumption of compressed air, achieving energy saving and emission reduction, but also prevents excessive ammonia from escaping into the flue gas, effectively controlling the increase in O2 content at the emission port.

[0034] Meanwhile, the device also ensures uniform distribution of ammonia gas within the flue through a rational design of the branch pipes 20 and flow distribution. This not only improves denitrification efficiency but also avoids the problem of denitrification temperature reduction caused by excessively high or low local temperatures.

[0035] In summary, the device for low-flow ammonia injection provided in this application, through its impact pin structure, effectively solves the problems of increased energy consumption, increased O2 content at the emission port, decreased denitrification temperature, and insufficient mixing of low-flow ammonia with flue gas.

[0036] In some embodiments of this application, the diameter of the through hole ranges from Φ1mm to Φ6mm, and the angle of the tapered end face of the striker 12 ranges from 60° to 120°.

[0037] The orifice diameter inside the diffusion-type ammonia injection nozzle 10 is controlled within the range of Φ1mm-Φ6mm. This size is derived from in-depth research and calculation of ammonia flow rate and injection velocity. The orifice diameter directly affects the injection volume and injection pressure of ammonia. When the orifice diameter is smaller, the injection volume of ammonia decreases accordingly, but the injection velocity increases, allowing the ammonia to be more finely distributed in the flue gas. Conversely, when the orifice diameter increases, the injection volume of ammonia increases, but the injection velocity decreases relatively, making it suitable for applications requiring a larger ammonia input. By adjusting the orifice diameter within this range, precise control of the ammonia flow rate can be achieved to meet the denitrification requirements under different operating conditions.

[0038] Meanwhile, the conical end face angle of the impact pin 12 is designed to be within the range of 60°-120°. This angle range optimizes the diffusion pattern and coverage of ammonia gas. When the conical end face angle is small, the ammonia gas diffuses outwards at a sharper angle after impact, forming a narrower spray cone angle. Conversely, when the conical end face angle increases, the diffusion angle of ammonia gas increases accordingly, the spray cone angle widens, and the coverage area expands. By adjusting the conical end face angle within this range, flexible control over the diffusion pattern and coverage of ammonia gas can be achieved, ensuring that ammonia gas is evenly distributed in the flue gas and improving denitrification efficiency.

[0039] In some embodiments of this application, there are multiple diffusion-type ammonia injection nozzles 10, which are evenly distributed on the distribution branch pipe 20. This design ensures uniform distribution of ammonia gas within the flue, avoiding a decrease in denitrification efficiency caused by excessively high or low local ammonia concentrations. The evenly spaced distribution of multiple nozzles also increases the number of ammonia injection points, improving the contact area between ammonia gas and flue gas, thereby enhancing the denitrification effect.

[0040] In some embodiments of this application, the jetting area of ​​multiple diffusion-type ammonia injection nozzles 10 is larger than the flue area. The nozzles 10 are arranged in a frontal, side, or cross configuration. To further optimize the ammonia injection effect, the jetting area of ​​the multiple diffusion-type ammonia injection nozzles 10 is designed to be larger than the flue area. This means that the ammonia injection range can cover the entire flue cross-section, ensuring that nitrogen oxides in the flue gas can fully react with ammonia, thereby improving denitrification efficiency. Simultaneously, this design can also reduce ammonia escape and lower environmental pollution.

[0041] In some embodiments of this application, the frontal arrangement is as follows: multiple diffusion-type ammonia injection nozzles 10 are arranged in the same direction on the distribution branch pipe 20, and the orientation of the diffusion-type ammonia injection nozzles 10 is the same as the axial direction of the flue. This arrangement is suitable for occasions where the flue gas flow velocity is relatively fast and it is necessary to enhance the mixing effect between ammonia and flue gas. Through frontal injection, ammonia can directly face the flue gas flow direction, achieving more thorough mixing and reaction.

[0042] The side-mounted arrangement involves multiple diffusion-type ammonia injection nozzles 10 arranged in the same direction on the distribution branch pipe 20, with the orientation of the diffusion-type ammonia injection nozzles 10 intersecting the axial direction of the flue. This arrangement is suitable for situations where the flue gas flow velocity is slow and an increased ammonia injection angle is required to cover a wider range. Through side injection, ammonia can be injected obliquely into the flue gas at a certain angle, expanding the injection range and improving denitrification efficiency.

[0043] The cross-arrangement involves multiple diffusion-type ammonia injection nozzles 10 arranged alternately on the distribution branch pipe 20, some facing the same axial direction as the flue gas and others facing a direction intersecting the axial direction of the flue gas. This arrangement enables comprehensive coverage of the flue gas, further improving denitrification efficiency. Furthermore, the cross-arrangement can be flexibly adjusted according to the flow velocity and concentration distribution of the flue gas to adapt to denitrification requirements under different operating conditions.

[0044] The design of the number, distribution, and arrangement of the diffusion-type ammonia injection nozzles 10 in this embodiment not only enhances the denitrification performance and applicability of the device but also improves the mixing effect and reaction efficiency of ammonia and flue gas. This design allows the device to more flexibly adapt to denitrification requirements under different operating conditions, achieving the goals of energy saving, emission reduction, and improved denitrification efficiency. Simultaneously, by optimizing the nozzle arrangement, the escape rate of ammonia can be further reduced, minimizing environmental pollution.

[0045] In some embodiments of this application, a flow distributor is provided in the distribution branch pipe 20; the flow distributor is fixed at the communication position between the diffusion-type ammonia injection nozzle 10 and the distribution branch pipe 20, and the flow distributor is used to control the flow rate of ammonia gas entering the diffusion-type ammonia injection nozzle 10.

[0046] The flow distributor is fixed at the connection point between the diffuser-type ammonia injection nozzle 10 and the distribution branch pipe 20, ensuring that ammonia gas is precisely regulated before entering each diffuser-type ammonia injection nozzle 10. The main function of the flow distributor is to precisely control the ammonia flow rate to each diffuser-type ammonia injection nozzle 10 according to actual needs. This function achieves uniform ammonia distribution, helping to reduce low denitrification efficiency and ammonia escape problems caused by uneven flow, thereby improving the overall denitrification effect and environmental performance.

[0047] In some embodiments of this application, a pressure compensator is also provided in the distribution branch pipe 20; the pressure compensator is located at the connection position between the distribution branch pipe 20 and the fixed accessory 30, and the pressure compensator is used to control the ammonia flow rate and pressure stability in the distribution branch pipe 20.

[0048] The pressure compensator is used to maintain the pressure stability of the ammonia flow rate within the distribution branch pipe 20. During actual operation, the ammonia pipeline system may experience pressure fluctuations due to changes in the external environment (such as temperature changes, differences in pipeline length, etc.), which can affect the stable supply of ammonia. The introduction of the pressure compensator can dynamically adjust and compensate for these pressure changes, ensuring that ammonia enters the diffusion-type ammonia injection nozzle 10 at a constant and appropriate pressure, further enhancing the stability and reliability of the system.

[0049] In some embodiments of this application, an elastic connector is provided between the distribution branch pipe 20 and the fixing accessory 30, and the elastic connector is a rubber pad or a spring.

[0050] The flexible connector is installed at the connection interface between the distribution branch pipe 20 and the fixed accessory 30. Its main function is to absorb and buffer minor displacements and vibrations caused by factors such as temperature changes, equipment operation vibrations, or wind, thereby effectively preventing stress concentration and potential leakage problems caused by these external factors. This design not only improves the overall stability of the system but also extends the service life of each component and reduces the risk of failure due to vibration.

[0051] In some embodiments of this application, a corrugated pipe is provided between the fixed attachment 30 and the flue, and a limiting device is provided on both sides of the corrugated pipe. The limiting device has a fixed end and a limiting end. The fixed end is fixedly connected to the flue, and the limiting end extends toward a position away from the flue. The projection of the limiting end on the flue overlaps at least partially with the corrugated pipe.

[0052] Among these features, the corrugated pipe, as a connecting element with good extensibility and flexibility, can adapt well to the slight deformation of the flue, ensuring a stable connection between the fixed accessory 30 and the flue. Secondly, the fixed end of the limiting device is connected to the flue, ensuring the structural stability. The projection of the limiting end on the flue at least partially overlaps with the corrugated pipe. This design not only ensures the freedom of the corrugated pipe during expansion and contraction but also effectively prevents damage to the corrugated pipe due to excessive stretching or compression through the physical restriction of the limiting end. This dual-protection design not only enhances the adaptability and durability of the system but also ensures the sealing and safety of the connection, further improving the operating efficiency and reliability of the entire denitrification system.

[0053] As described above, the ammonia injection device for small flow rates provided in this application aims to optimize the distribution, injection, and adaptability of ammonia gas to flue gas changes, thereby achieving a highly efficient, stable, and economical denitrification process. Ammonia gas is introduced into the distribution branch pipe from the source and, after precise control by the flow distributor and pressure compensator, is delivered to each diffuser-type ammonia injection nozzle. The ammonia gas is injected into the flue gas through the diffuser-type ammonia injection nozzle 10 at a predetermined angle and flow rate, and diffuses outwards upon impact with the conical end face of the impactor, fully mixing with the flue gas to form an ammonia-flue gas mixture conducive to the denitrification reaction. Inside the flue gas, the ammonia gas reacts chemically with nitrogen oxides in the flue gas to generate harmless nitrogen gas and water vapor, achieving the denitrification purpose. As the flue gas environment changes, the flexible connectors, bellows, and their limiting devices automatically adjust to ensure stable operation of the device and effective denitrification.

[0054] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the disclosure in the specification and the embodiments. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein.

Claims

1. A device for small-flow ammonia injection, characterized in that, It includes a diffusion-type ammonia injection nozzle (10), a distribution branch pipe (20), and a fixing accessory (30); One end of the diffusion-type ammonia injection nozzle (10) is fixed on the cylindrical surface of the distribution branch pipe (20) and communicates with the distribution branch pipe (20). One end of the distribution branch pipe (20) is fixed and communicated with the flue through the fixing accessory (30). The diffuser ammonia injection nozzle (10) has a through hole. The diffuser ammonia injection nozzle (10) has a nozzle (11) at one end away from the distribution branch pipe (20). A striker (12) is provided at the edge of the nozzle (11). The striker (12) has a tapered end face at one end away from the nozzle (11). The tapered end face is opposite to the center of the nozzle (11).

2. The ammonia injection device for low flow rates according to claim 1, characterized in that, The diameter of the through hole ranges from Φ1mm to Φ6mm.

3. The ammonia injection device for small flow rates according to claim 1, characterized in that, The angle range of the tapered end face of the striker (12) is 60°-120°.

4. The ammonia injection device for small flow rates according to claim 1, characterized in that, The number of the diffusion-type ammonia injection nozzles (10) is multiple, and the diffusion-type ammonia injection nozzles (10) are evenly distributed on the distribution branch pipe (20).

5. A small-flow ammonia injection device according to claim 4, characterized in that, The jetting area of ​​the plurality of diffusion-type ammonia injection nozzles (10) is larger than the flue area, and the arrangement of the nozzles of the diffusion-type ammonia injection nozzles (10) includes front arrangement, side arrangement and cross arrangement.

6. A small-flow ammonia injection device according to claim 5, characterized in that, The front arrangement is as follows: multiple diffusion-type ammonia injection nozzles (10) are arranged in the same direction on the distribution branch pipe (20), and the orientation of the diffusion-type ammonia injection nozzles (10) is the same as the axial direction of the flue. The side arrangement is as follows: multiple diffusion-type ammonia injection nozzles (10) are arranged in the same direction on the distribution branch pipe (20), and the orientation of the diffusion-type ammonia injection nozzles (10) intersects with the axial direction of the flue. The cross arrangement is as follows: multiple diffusion-type ammonia injection nozzles (10) are arranged alternately on the distribution branch pipe (20) in the same direction as the axial direction of the flue and in a direction that crosses the axial direction of the flue.

7. A small-flow ammonia injection device according to claim 1, characterized in that, The distribution branch pipe (20) is equipped with a flow distributor; The flow distributor is fixed at the connection position between the diffusion-type ammonia injection nozzle (10) and the distribution branch pipe (20), and the flow distributor is used to control the flow rate of ammonia gas entering the diffusion-type ammonia injection nozzle (10).

8. A small-flow ammonia injection device according to claim 1, characterized in that, A pressure compensator is also provided in the distribution branch pipe (20); the pressure compensator is located at the connection position between the distribution branch pipe (20) and the fixed accessory (30), and the pressure compensator is used to control the ammonia flow rate and pressure stability in the distribution branch pipe (20).

9. A small-flow ammonia injection device according to claim 1, characterized in that, An elastic connector is provided between the distribution branch pipe (20) and the fixing accessory (30), and the elastic connector is a rubber pad or a spring.

10. A small-flow ammonia injection device according to claim 1, characterized in that, A corrugated pipe is provided between the fixed accessory (30) and the flue. Limiting devices are provided on both sides of the corrugated pipe. The limiting device has a fixed end and a limiting end. The fixed end is fixedly connected to the flue. The limiting end extends toward a position away from the flue, and the projection of the limiting end on the flue overlaps at least partially with the corrugated pipe.

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