An ammonia injection device for SCR denitration of a coal-fired boiler environmental protection project

Abstract

This invention relates to the field of denitrification devices, specifically an SCR ammonia injection device for environmental protection engineering of coal-fired boilers. It consists of multiple ammonia injection modules arranged in parallel to form an ammonia injection grid. Each ammonia injection module includes an outer pipe inserted into the flue, multiple nozzle mounting pipes mounted on the outer pipe, a sealing plate on the inner wall of the nozzle mounting pipes, nozzles fitted onto the nozzle mounting pipes, and an external cleaning airflow pipe and an internal cleaning airflow pipe inserted into the outer pipe. The outer pipe is sealed at one end, with an ammonia inlet pipe at the sealed end. The sealing plate has vent holes for ammonia passage and an internal cleaning connection pipe, which connects to the internal cleaning airflow pipe. The external cleaning airflow pipe and the internal cleaning airflow pipe are connected to an external air supply device. An external purging mechanism for purging nozzles is installed on the outer pipe, and the external purging mechanism is connected to the external cleaning airflow pipe. This invention solves the problems of difficult ash cleaning and high maintenance risks in traditional SCR ammonia injection devices through an innovative modular ammonia injection grid and intelligent cleaning system.

Description

Technical Field

[0001] This invention relates to the field of denitrification equipment technology, and in particular to an SCR denitrification ammonia injection device for environmental protection engineering of coal-fired boilers. Background Technology

[0002] Coal-fired boilers are important thermal energy equipment in energy supply and industrial production, but they produce nitrogen oxides (NOx) during combustion. x NOx is one of the major air pollutants, posing a threat to the environment and human health. Selective catalytic reduction (SCR) denitrification technology is one of the most widely used and efficient flue gas denitrification technologies. Its principle is that, under the action of a catalyst, a reducing agent (usually ammonia or urea) is used to remove NOx from the flue gas. x It is reduced to nitrogen and water, thus achieving efficient denitrification.

[0003] In an SCR denitrification system, the ammonia injection unit is one of the key pieces of equipment, responsible for uniformly and accurately injecting the reducing agent into the flue gas, causing it to react with NO. x Thorough mixing and reaction on the catalyst surface are achieved. Currently, most common ammonia injection devices employ an ammonia injection grid (AIG) structure, which distributes multiple nozzles or injection pipes across the flue gas cross-section, combined with a static mixer or flow guide device to optimize the mixing effect of ammonia and flue gas.

[0004] After a period of use, the nozzles of the existing ammonia spraying grid will accumulate a lot of dust. Manual cleaning is time-consuming and laborious, and also poses safety hazards. The added airflow purging structure has the problem of incomplete purging. In addition, the ammonia spraying grid is fixed in the flue, making cleaning and maintenance very difficult. Summary of the Invention

[0005] The purpose of this invention is to address the problems of incomplete airflow purging and difficulty in maintenance caused by the airflow being fixed inside the flue in the prior art, and to propose an SCR denitrification ammonia injection device for environmental protection engineering of coal-fired boilers.

[0006] The technical solution of this invention: An SCR denitrification ammonia injection device for a coal-fired boiler environmental protection project, comprising multiple ammonia injection modules arranged in parallel to form an ammonia injection grid; each ammonia injection module includes an outer pipe inserted into the flue, multiple nozzle mounting pipes mounted on the outer pipe, a sealing plate mounted on the inner wall of the nozzle mounting pipe, nozzles fitted on the nozzle mounting pipe, and an outer clean airflow pipe and an inner clean airflow pipe inserted into the outer pipe; the flue is provided with a through hole for the outer pipe to pass through, the end of the outer pipe is sealed, an ammonia inlet pipe is provided at the sealed end of the outer pipe, the sealing plate is provided with a vent hole for ammonia to pass through and an inner clean connection pipe, the inner clean connection pipe is connected to the inner clean airflow pipe, and the outer clean airflow pipe and the inner clean airflow pipe are connected to an external gas supply device; the outer pipe is provided with an external purging mechanism for purging nozzles, and the external purging mechanism is connected to the outer clean airflow pipe.

[0007] Preferably, a positioning post is coaxially provided at one end of the outer tube, and a positioning hole is provided on the positioning post. A positioning rod is provided on the inner wall of the flue, and the positioning rod is inserted into the positioning hole. A fixing flange is provided on the outer peripheral wall of the other end of the outer tube, and the fixing flange is connected to the outer wall of the flue.

[0008] Preferably, the outer pipe is composed of multiple sub-outer pipes, each of which is provided with a connecting flange at both ends, and adjacent sub-outer pipes are connected by the connecting flange.

[0009] Preferably, an inner tube is installed inside the outer tube, with one end of the inner tube located outside the outer tube. Both the outer cleaning airflow pipe and the inner cleaning airflow pipe are inserted into the inner tube, and the inner cleaning connecting pipe passes through the inner tube wall.

[0010] Preferably, the top of the nozzle is provided with a conical surface, and multiple ammonia injection holes are provided on the conical surface along the circumferential direction. A hexagonal prism is provided on the top of the conical surface.

[0011] Preferably, the external purging mechanism includes a hollow ring located on the outer periphery of the nozzle, a connecting pipe disposed at the bottom of the hollow ring, and an external cleaning connecting pipe disposed on the external cleaning airflow pipe. The external cleaning connecting pipe and the connecting pipe are sealed together, and multiple air outlet holes facing the conical surface are provided on the inner wall of the hollow ring.

[0012] Preferably, both the external and internal cleaning airflow pipes are equipped with square closed pipes at their inlet ends. An airflow inlet pipe is installed on the square closed pipe. The airflow is divided into two airflow channels through the airflow inlet pipe and the square closed pipe and enters the external or internal cleaning airflow pipe. An electromagnetic flow valve and an electromagnetic pulse valve are respectively installed on the two airflow channels.

[0013] Preferably, it also includes a control system, which is connected to both the electromagnetic flow valve and the electromagnetic pulse valve.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: 1. Dual-channel pulse cleaning: The internal and external cleaning airflow pipes have clearly defined functions. The pulse airflow can powerfully remove stubborn dust and avoid the problem of incomplete cleaning by traditional blowing. 2. Dynamic anti-clogging design: During operation, low flow positive pressure continuously suppresses the formation of dust accumulation, reducing the frequency of downtime for cleaning; 3. Convenient and safe maintenance: The outer tube can be pulled out from the flue, and the nozzles can be installed independently, allowing for maintenance without entering the flue. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of one embodiment of the present invention; Figure 2 This is a schematic diagram of the internal structure of the outer tube; Figure 3 This is a schematic diagram of the internal structure of the outer tube after it has been cut open along its length. Figure 4 This is a schematic diagram of the nozzle and the cavity ring. Figure 5 This is a schematic diagram of the ammonia injection grid structure; Reference numerals: 1. Outer pipe; 2. Inner pipe; 3. Positioning post; 4. Positioning rod; 5. Sub-outer pipe; 6. Nozzle mounting pipe; 7. Nozzle; 8. Conical surface; 9. Ammonia spray hole; 10. Hexagonal column; 11. Sealing plate; 12. Vent hole; 13. External cleaning airflow pipe; 14. Internal cleaning airflow pipe; 15. Internal cleaning connecting pipe; 16. External cleaning connecting pipe; 17. Hollow ring; 18. Air outlet; 19. Square closed pipeline; 20. Airflow inlet pipe; 21. Electromagnetic flow valve; 22. Electromagnetic pulse valve; 23. Ammonia inlet pipe; 24. Fixed flange; 25. Connecting flange; 26. Butt joint pipe. Detailed Implementation

[0016] Example 1; as Figures 1-5 As shown, the present invention proposes an SCR denitrification ammonia injection device for a coal-fired boiler environmental protection project, which consists of multiple ammonia injection modules arranged in parallel to form an ammonia injection grid. The ammonia injection module includes an outer pipe 1 inserted into the flue, multiple nozzle mounting pipes 6 set on the outer pipe 1, a sealing plate 11 set on the inner wall of the nozzle mounting pipe 6, nozzles 7 sleeved on the nozzle mounting pipe 6, and an external cleaning airflow pipe 13 and an internal cleaning airflow pipe 14 inserted into the outer pipe 1. The flue is provided with a through hole for the outer pipe 1 to pass through, the end of the outer pipe 1 is sealed, and an ammonia inlet pipe 23 is set at the sealed end of the outer pipe 1. The sealing plate 11 is provided with a vent hole 12 for ammonia to pass through and an internal cleaning connection pipe 15. The internal cleaning connection pipe 15 is connected to the internal cleaning airflow pipe 14, and the external cleaning airflow pipe 13 and the internal cleaning airflow pipe 14 are connected to an external gas supply device. An external purging mechanism for the purging nozzles 7 is provided on the outer pipe 1, and the external purging mechanism is connected to the external cleaning airflow pipe 13.

[0017] Furthermore, a positioning post 3 is coaxially provided at one end of the outer tube 1, and a positioning hole is provided on the positioning post 3. A positioning rod 4 is provided on the inner wall of the flue, and the positioning rod 4 is inserted into the positioning hole to provide positioning and support for the outer tube 1. A fixing flange 24 is provided on the outer peripheral wall of the other end of the outer tube 1, and a sealing connection is achieved by connecting the fixing flange 24 to the outer wall of the flue.

[0018] Furthermore, the outer tube 1 is composed of multiple sub-outer tubes 5, and each sub-outer tube 5 is provided with connecting flanges 25 at both ends. Adjacent sub-outer tubes 5 are connected through connecting flanges 25. The outer tube 1 can be disassembled, which facilitates modular manufacturing.

[0019] Furthermore, an inner tube 2 is installed inside the outer tube 1, with one end of the inner tube 2 located outside the outer tube 1. Both the outer cleaning airflow pipe 13 and the inner cleaning airflow pipe 14 are inserted into the inner tube 2. The inner cleaning connecting pipe 15 passes through the wall of the inner tube 2 and is completely located inside the outer tube 1. After the outer tube 1 is fitted onto the inner tube 2, the sealing plate 11 is installed. The sealing plate 11 is directly welded to the inner wall of the nozzle mounting pipe 6. Then, the inner cleaning connecting pipe 15 is welded to the bottom of the sealing plate 11 through the pre-drilled through hole. Circumferential welding is required to achieve a tight seal and prevent air leakage.

[0020] Example 2; as Figures 3-4 As shown, this invention proposes an SCR denitrification ammonia injection device for a coal-fired boiler environmental protection project. Compared with Embodiment 1, this embodiment details the external cleaning mechanism. A conical surface 8 is provided at the top of the nozzle 7, and multiple ammonia injection holes 9 are provided on the conical surface 8 along the circumferential direction. A hexagonal prism 10 is provided at the top of the conical surface 8 to facilitate the rotation of the nozzle 7 to complete the threaded connection with the nozzle mounting pipe 6.

[0021] The external purging mechanism includes a hollow ring 17 located around the nozzle 7, a connecting pipe 26 located at the bottom of the hollow ring 17, and an external cleaning connecting pipe 16 located on the external cleaning airflow pipe 13. The external cleaning connecting pipe 16 and the connecting pipe 26 are sealed together. The inner wall of the hollow ring 17 is provided with multiple air outlet holes 18 facing the conical surface 8. The outer pipe 1 is provided with a through hole. During installation, after the outer pipe 1 is fitted onto the inner pipe 2, the external cleaning connecting pipe 16 is aligned with the through hole and is circumferentially welded from the outside to achieve a sealed connection between the external cleaning connecting pipe 16 and the pipe wall of the outer pipe 1. Then, the hollow ring 17 is installed in place. At this time, the external cleaning connecting pipe 16 and the connecting pipe 26 are exactly opposite each other. The hollow ring 17 and the connecting pipe 26 are lowered to the lowest point so that the connecting pipe 26 is inserted into the through hole on the outer pipe 1 and abuts against the external cleaning connecting pipe 16. Then, circumferential welding is performed to achieve a sealed connection between the connecting pipe 26 and the pipe wall of the outer pipe 1.

[0022] Example 3; as Figure 1 As shown, the present invention proposes an SCR denitrification ammonia injection device for environmental protection engineering of coal-fired boilers. Compared with Embodiment 2, this embodiment details the airflow control structure and control method during cleaning.

[0023] Both the external cleaning airflow pipe 13 and the internal cleaning airflow pipe 14 are provided with square closed pipes 19 at their inlet ends. An airflow inlet pipe 20 is provided on the square closed pipe 19. The airflow is divided into two airflow channels through the airflow inlet pipe 20 and the square closed pipe 19 and enters the external cleaning airflow pipe 13 or the internal cleaning airflow pipe 14. An electromagnetic flow valve 21 and an electromagnetic pulse valve 22 are respectively provided on the two airflow channels.

[0024] The entire device is also equipped with a control system, which is connected to both the electromagnetic flow valve 21 and the electromagnetic pulse valve 22. In the ammonia injection state, both electromagnetic flow valves 21 are opened according to the set flow rate, continuously releasing air at a low flow rate to maintain positive pressure in the external cleaning airflow pipe 13 and the internal cleaning airflow pipe 14, preventing ammonia from entering the external cleaning airflow pipe 13 and the internal cleaning airflow pipe 14. In the internal cleaning state, the electromagnetic flow valve 21 is closed, and the corresponding electromagnetic pulse valve 22 is opened. High-pressure air is ejected in a pulse manner through the internal cleaning connecting pipe 15 or the air outlet 18 to achieve internal or external cleaning. It should be noted that when performing external cleaning, the electromagnetic flow valve 21 on the square closed pipe 19 corresponding to the internal cleaning airflow pipe 14 needs to increase its opening to increase the airflow rate, preventing the external pulse airflow from blowing the accumulated dust into the nozzle 7 through the ammonia injection hole 9.

[0025] In summary, during use, ammonia gas enters the outer pipe 1 through the ammonia inlet pipe 23, is diverted to each nozzle 7 through the vent hole 12 of the sealing plate 11, and is evenly sprayed out from the ammonia spray hole 9 on the conical surface 8. The electromagnetic flow valve 21 is normally open, and the cleaning system maintains a low flow rate and positive pressure. During external cleaning, the electromagnetic flow valve 21 of the external cleaning airflow pipe 13 is closed, and the electromagnetic pulse valve 22 is opened. The high-pressure pulse airflow is sprayed out from the vent hole 18 of the cavity ring 17 to remove the accumulated dust on the conical surface 8 of the nozzle 7. During internal cleaning, the electromagnetic flow valve 21 of the internal cleaning airflow pipe 14 is closed, and the electromagnetic pulse valve 22 is opened. The pulse airflow is reversed through the internal cleaning connecting pipe 15 to flush the inner wall of the nozzle mounting pipe 6. During external cleaning, the flow rate of the internal cleaning airflow pipe 14 is increased to prevent accumulated dust from flowing back into the ammonia spray hole 9. Disassembly and maintenance: Loosen the fixing flange 24, pull out the outer tube 1, and ensure the reassembly accuracy by cooperating with the positioning rod 4 and the positioning column 3. The nozzle 7 can be disassembled and installed by rotating the hexagonal column 10, which is convenient for replacement or cleaning.

[0026] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. An SCR denitrification ammonia injection device for environmental protection engineering of coal-fired boilers, characterized in that, An ammonia injection grid is formed by arranging multiple ammonia injection modules in parallel. Each ammonia injection module includes an outer pipe (1) inserted into the flue, multiple nozzle mounting pipes (6) mounted on the outer pipe (1), a sealing plate (11) mounted on the inner wall of the nozzle mounting pipes (6), nozzles (7) fitted onto the nozzle mounting pipes (6), and an outer cleaning airflow pipe (13) and an inner cleaning airflow pipe (14) inserted into the outer pipe (1). A through hole is provided on the flue for the outer pipe (1) to pass through, and the end of the outer pipe (1)... The outer pipe (1) is sealed, and an ammonia inlet pipe (23) is provided at the sealed end. The sealing plate (11) is provided with a vent hole (12) for ammonia to pass through and an inner cleaning connection pipe (15). The inner cleaning connection pipe (15) is connected to the inner cleaning airflow pipe (14). The outer cleaning airflow pipe (13) and the inner cleaning airflow pipe (14) are connected to the external gas supply equipment. The outer pipe (1) is provided with an external purging mechanism of a purging nozzle (7). The external purging mechanism is connected to the external cleaning airflow pipe (13).

2. The SCR denitrification ammonia injection device for coal-fired boiler environmental protection engineering according to claim 1, characterized in that, A positioning post (3) is coaxially set at one end of the outer tube (1), and a positioning hole is set on the positioning post (3). A positioning rod (4) is set on the inner wall of the flue, and the positioning rod (4) is inserted into the positioning hole. A fixed flange (24) is set on the outer peripheral wall of the other end of the outer tube (1), and is connected to the outer wall of the flue through the fixed flange (24).

3. The SCR denitrification ammonia injection device for environmental protection engineering of coal-fired boilers according to claim 1, characterized in that, The outer pipe (1) is composed of multiple sub-outer pipes (5), and each sub-outer pipe (5) is provided with connecting flanges (25) at both ends. Two adjacent sub-outer pipes (5) are connected through connecting flanges (25).

4. The SCR denitrification ammonia injection device for coal-fired boiler environmental protection engineering according to claim 1, characterized in that, An inner tube (2) is installed inside the outer tube (1). One end of the inner tube (2) is located outside the outer tube (1). The outer cleaning airflow pipe (13) and the inner cleaning airflow pipe (14) are both inserted into the inner tube (2). The inner cleaning connecting pipe (15) passes through the wall of the inner tube (2).

5. The SCR denitrification ammonia injection device for environmental protection engineering of coal-fired boilers according to claim 1, characterized in that, The nozzle (7) has a conical surface (8) at the top, and multiple ammonia injection holes (9) are provided on the conical surface (8) along the circumferential direction. A hexagonal prism (10) is provided on the top of the conical surface (8).

6. The SCR denitrification ammonia injection device for environmental protection engineering of coal-fired boilers according to claim 5, characterized in that, The external purging mechanism includes a cavity ring (17) located on the outer periphery of the nozzle (7), a connecting pipe (26) located at the bottom of the cavity ring (17), and an external cleaning connecting pipe (16) located on the external cleaning airflow pipe (13). The external cleaning connecting pipe (16) and the connecting pipe (26) are sealed together. Multiple air outlets (18) facing the conical surface (8) are provided on the inner wall of the cavity ring (17).

7. The SCR denitrification ammonia injection device for coal-fired boiler environmental protection engineering according to claim 6, characterized in that, Both the external cleaning airflow pipe (13) and the internal cleaning airflow pipe (14) are equipped with square closed pipes (19) at their inlet ends. An airflow inlet pipe (20) is installed on the square closed pipe (19). The airflow is divided into two airflow channels through the airflow inlet pipe (20) and the square closed pipe (19) and enters the external cleaning airflow pipe (13) or the internal cleaning airflow pipe (14). An electromagnetic flow valve (21) and an electromagnetic pulse valve (22) are installed on the two airflow channels respectively.

8. The SCR denitrification ammonia injection device for coal-fired boiler environmental protection engineering according to claim 7, characterized in that, It also includes a control system, which is connected to both the electromagnetic flow valve (21) and the electromagnetic pulse valve (22).

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