Boiler denitration device

Abstract

This utility model discloses a boiler denitrification device, relating to the field of boiler denitrification technology. The device includes a hot air duct, one end of which is connected to the main hot primary air duct at the outlet of an adjacent boiler air preheater, and the other end of which is connected to the pyrolysis air source duct of the urea pyrolysis device in this boiler denitrification system. This duct is used to provide backup hot air to the urea pyrolysis device during maintenance of the boiler's primary air fan. By introducing hot primary air from the outlet of an adjacent boiler air preheater as a backup heat source, this utility model establishes a cross-boiler hot air supply channel, solving the problem of air source interruption in the urea pyrolysis system during primary air fan maintenance and ensuring the continuous and stable operation of the denitrification device.

Description

Technical Field

[0001] This utility model relates to the field of boiler denitrification technology, and in particular to a boiler denitrification device. Background Technology

[0002] In the flue gas denitrification system of coal-fired power plant boilers, the urea pyrolysis unit requires high-temperature hot air as a pyrolysis medium to decompose urea solution into ammonia gas for SCR denitrification reaction. This hot air usually comes from the hot primary air at the outlet of the boiler's air preheater and is delivered by the primary air fan. However, when the boiler's primary air fan is under maintenance, malfunctioning, or operating on one side, the supply of hot primary air is interrupted, causing the urea pyrolysis system to malfunction, which in turn forces the denitrification unit to shut down, posing a risk of excessive nitrogen oxide emissions and seriously affecting the power plant's environmental compliance and the unit's operational flexibility.

[0003] In existing technologies, some power plants use electric heating or steam heating as backup heat sources, but these methods have problems such as high energy consumption, large investment, and slow response. Other solutions attempt to set up independent backup fans, but these methods require a large area and are complex.

[0004] Therefore, there is an urgent need for a simple, reliable, economical and efficient backup hot air supply solution to ensure the continuous operation of the urea pyrolysis system under various operating conditions. Utility Model Content

[0005] This utility model provides a boiler denitrification device, including a hot air duct. One end of the hot air duct is connected to the main hot primary air duct at the outlet of the adjacent boiler air preheater, and the other end of the hot air duct is connected to the pyrolysis air source duct of the boiler denitrification urea pyrolysis device. It is used to provide backup hot air to the urea pyrolysis device when the primary air fan of the boiler is under maintenance.

[0006] Preferably, the hot air duct is equipped with a control valve to control the flow rate and pressure of the hot primary air.

[0007] Preferably, the hot air duct is equipped with a temperature sensor for monitoring the temperature of the primary hot air.

[0008] Preferably, the hot air duct is equipped with a pressure sensor to monitor the pressure of the primary hot air.

[0009] Preferably, the hot air duct is equipped with a flow meter for monitoring the flow rate of the hot primary air.

[0010] Preferably, the hot air duct is connected to a filter shell near the pyrolysis air source duct of the urea pyrolysis device. Connecting pipes are provided on both sides of the filter shell, and the two sets of connecting pipes are respectively connected to the two ends of the hot air duct. Two sets of filter plates are movably installed inside the filter shell.

[0011] Preferably, the filter housing is provided with a retainer near the bottom, the bottom of the filter plate is engaged in the retainer, and the upper end of the filter housing is sealed by a cover plate.

[0012] Preferably, the bottom of the filter housing is provided with a conical hopper, and a valve is provided on the conical hopper.

[0013] Preferably, the rotating rod passes through both sets of filter plates and is rotatably connected to the filter plates. One end of the rotating rod is connected to the output shaft of the motor. Two brushes are fixedly connected to the rotating rod, and the two brushes are respectively attached to the two filter plates.

[0014] Preferably, the pyrolysis air source duct of the urea pyrolysis device is welded with a pipe seat, and one end of the hot air duct is provided with an extension sleeve. The extension sleeve is inserted into the pipe seat and forms a compression seal with the sealing ring set between the two. The pipe seat and the hot air duct are fastened together by a flange structure to form a detachable airtight connection interface.

[0015] The boiler denitrification device provided in this embodiment of the utility model, compared with the prior art:

[0016] 1. This utility model introduces hot primary air from the outlet of the air preheater of an adjacent boiler into the denitrification urea pyrolysis system of this boiler, thus constructing a backup hot air supply channel across boilers. This effectively solves the technical problem of interruption of pyrolysis air source during maintenance of the primary air fan of this boiler or operation on one side. This structure ensures that the urea pyrolysis system can obtain a stable and high-temperature hot air supply under various operating conditions, avoiding the problem of denitrification device shutdown due to insufficient air source, improving the continuous operation capability and emission compliance rate of power plant environmental protection facilities, and has outstanding environmental benefits and operating economy.

[0017] 2. This utility model features a filter housing with filter plates, brushes, and an automatic dust removal mechanism at the end of the hot air duct, along with a conical hopper dust discharge structure. This effectively intercepts dust or foreign objects that may be carried in the hot air, preventing blockage of the pyrolysis air duct. Simultaneously, the motor-driven brushes periodically clean the filter plates, achieving online dust removal and reducing the frequency of manual maintenance. Furthermore, the hot air duct and the pyrolysis air source duct are connected by a detachable method using pipe socket insertion, sealing ring compression, and flange fastening. This not only ensures airtightness under high-temperature conditions but also facilitates installation, alignment, and subsequent maintenance and disassembly. The overall structure boasts high reliability, convenient maintenance, and strong adaptability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model;

[0020] Figure 2 This is a side view of the overall structure of an embodiment of the present utility model;

[0021] Figure 3 This is a schematic diagram of the structure of the hot air duct and other components according to an embodiment of the present utility model;

[0022] Figure 4 This is a schematic diagram of the structure of the filter shell and other components according to an embodiment of the present utility model;

[0023] Figure 5 This is an embodiment of the present utility model. Figure 4 Top view of the structure;

[0024] Figure 6 The following is an embodiment of this utility model Figure 5 Schematic diagram of cross section at point AA;

[0025] Figure 7 This is a top view of the connection structure between the pipe seat and the hot air duct in an embodiment of the present invention;

[0026] Figure 8 The following is an embodiment of this utility model Figure 7 Schematic diagram of cross-section at BB.

[0027] Figure label:

[0028] 1. Urea pyrolysis unit; 2. Hot air duct; 3. Control valve; 4. Pipe seat; 5. Extension sleeve; 6. Sealing ring; 7. Temperature sensor; 8. Pressure sensor; 9. Flow meter; 10. Filter housing; 11. Connecting pipe; 12. Conical hopper; 13. Holder; 14. Filter plate; 15. Rotating rod; 16. Brush; 17. Motor. Detailed Implementation

[0029] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0030] Please refer to Figures 1-8 This utility model provides a boiler denitrification device, including a hot air duct 2. One end of the hot air duct 2 is connected to the hot primary air main duct at the outlet of the air preheater of an adjacent boiler, and the other end is connected to the pyrolysis air source duct of the boiler denitrification urea pyrolysis device 1. It is used to introduce the high-temperature hot primary air generated by the adjacent boiler as a backup heat source into the boiler urea pyrolysis device 1 to replace the hot air supply missing when the boiler primary air fan is shut down.

[0031] Hot air duct 2 is made of carbon steel. The outer wall of the duct is covered with a high-temperature resistant insulation layer with a thickness of not less than 80mm. The insulation material can be rock wool or aluminum silicate fiber. The outer shell is equipped with aluminum or stainless steel to reduce heat loss and prevent burns to personnel.

[0032] A control valve 3 is installed on the hot air duct 2. The control valve 3 is an electric butterfly valve or an electric gate valve. It is installed in the middle section of the hot air duct 2 and its opening and closing status is remotely controlled by the DCS control system. It is used to open the hot air passage when needed and adjust the hot air flow and pressure to ensure that the air volume entering the urea pyrolysis unit 1 meets the process requirements.

[0033] like Figure 2 As shown, in order to further realize real-time monitoring of hot air parameters, the hot air duct 2 is also equipped with a temperature sensor 7, a pressure sensor 8 and a flow meter 9. The temperature sensor 7 is a platinum resistance Pt100 and is installed in the straight pipe section downstream of the control valve 3. The pressure sensor 8 is a piezoresistive transmitter and the flow meter 9 is a thermal mass flow meter or an integrated Pitot tube flow meter. All sensor signals are connected to the DCS system of this boiler and participate in interlocking control.

[0034] like Figures 4 to 6 As shown, in order to prevent dust, welding slag or ash that may be carried in the hot air from entering the urea pyrolysis unit 1, a filter shell 10 is connected to the part of the hot air duct 2 near the pyrolysis air source duct of the urea pyrolysis unit 1. The filter shell 10 has a rectangular structure and its two ends are connected to the flange of the hot air duct 2 through the connecting pipe 11 to form a straight-through filter structure.

[0035] Two sets of filter plates 14 are movably installed inside the filter housing 10. The filter plates 14 are stainless steel woven mesh plates, arranged vertically, and are used to intercept particulate impurities. The bottom of the filter plates 14 is inserted into the brackets 13 set at the bottom of the filter housing 10 for positioning and support. The top is sealed by a cover plate, which is removable for easy replacement or cleaning of the filter plates 14.

[0036] The bottom of the filter housing 10 is provided with a cone hopper 12, which is a conical dust collection structure. The lower end is provided with a dust discharge valve, which is a manual ball valve or a pneumatic butterfly valve, used to periodically discharge accumulated dust and impurities to prevent clogging.

[0037] To further realize the automatic dust removal function, the filter housing 10 also includes a rotating rod 15, two brushes 16 and a drive motor 17. The rotating rod 15 passes through the two filter plates 14, and its two ends are rotatably connected to the filter plates 14 through bearing seats. One end of the rotating rod 15 is connected to the output shaft of the drive motor 17. The motor 17 is a geared motor or a stepper motor, which can be set to start and stop periodically through a time relay or DCS system.

[0038] Two brushes 16 are fixedly sleeved on the rotating rod 15 and respectively attached to the two sets of filter plates 14. The brush bristles are made of high-temperature resistant nylon or stainless steel wire and have a certain degree of elasticity. When the rotating rod 15 rotates, it can continuously clean the surface of the filter plate 14 and sweep the attached dust into the cone hopper 12 for discharge. The motor 17 drives the rotating rod 15 to rotate forward and backward, moving the angle so that the brushes 16 swing left and right to a certain extent. This prevents the brushes 16 from touching the filter shell 10 and also cleans the filter plates 14.

[0039] like Figure 8 As shown, in order to achieve a reliable, airtight and easy-to-disassemble connection between the hot air duct 2 and the pyrolysis air source duct of this boiler, a pipe seat 4 is welded on the pyrolysis air source duct of the urea pyrolysis device 1. The pipe seat 4 is a circular socket-type short pipe with an inner diameter slightly larger than the outer diameter of the extension sleeve 5 at the end of the hot air duct 2.

[0040] One end of the hot air duct 2 is provided with an extension sleeve 5, which is a concentric short pipe with a reduced outer diameter. It is inserted into the pipe seat 4. An annular sealing ring 6 is provided at the joint between the extension sleeve 5 and the pipe seat 4. The sealing ring 6 is a high-temperature resistant metal spiral wound gasket or a graphite composite sealing ring, which is installed in the groove on the end face of the pipe seat 4. When the flange is tightened, it undergoes radial deformation under axial pressure to form a reliable airtight seal.

[0041] Pipe seat 4 is fastened to hot air duct 2 through a flange structure. The flange is a standard flat welding or butt welding flange, which is tightened evenly with high-strength bolts and equipped with anti-loosening gaskets. This connection structure not only ensures the sealing performance under high temperature conditions, but also allows a certain degree of thermal expansion displacement, and facilitates quick disassembly and reinstallation during maintenance.

[0042] In summary, the hot primary air from the outlet of the adjacent boiler air preheater is transported through the hot air duct 2. The flow rate and pressure are regulated by the control valve 3. The parameters are monitored in real time by the temperature sensor 7, pressure sensor 8, and flow meter 9 and fed back to the DCS system. After the hot air enters the filter shell 10, it is intercepted by the filter plate 14. The motor 17 drives the rotating rod 15 to drive the brush 16 to swing left and right on the surface of the filter plate 14 to clean it. The dust falls into the cone hopper 12 and is discharged through the valve. The clean hot air is inserted into the pipe seat 4 through the extension sleeve 5 and forms a compression seal with the sealing ring 6. Then it enters the urea pyrolysis unit 1 through the flange connection to achieve a stable supply of standby hot air.

[0043] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A boiler denitrification device, characterized in that: It includes a hot air duct (2), one end of which is connected to the hot primary air main duct at the outlet of the adjacent boiler air preheater, and the other end of which is connected to the pyrolysis air source duct of the denitrification urea pyrolysis device (1) of this boiler, for providing backup hot air to the urea pyrolysis device (1) when the primary air fan of this boiler is under maintenance.

2. The boiler denitrification device according to claim 1, characterized in that: The hot air duct (2) is equipped with a control valve (3) for controlling the flow rate and pressure of the hot primary air.

3. The boiler denitrification device according to claim 2, characterized in that: The hot air duct (2) is equipped with a temperature sensor (7) for monitoring the temperature of the primary hot air.

4. The boiler denitrification device according to claim 3, characterized in that: The hot air duct (2) is equipped with a pressure sensor (8) for monitoring the pressure of the primary hot air.

5. The boiler denitrification device according to claim 4, characterized in that: The hot air duct (2) is equipped with a flow meter (9) for monitoring the flow rate of the hot primary air.

6. The boiler denitrification device according to claim 1, characterized in that: The hot air duct (2) is connected to the pyrolysis air source duct of the urea pyrolysis device (1) by a filter shell (10). Both sides of the filter shell (10) are provided with connecting pipes (11). The two sets of connecting pipes (11) are respectively connected to the two ends of the hot air duct (2). Two sets of filter plates (14) are movably installed inside the filter shell (10).

7. The boiler denitrification device according to claim 6, characterized in that: The filter housing (10) is provided with a retainer (13) near the bottom, the bottom of the filter plate (14) is engaged in the retainer (13), and the upper end of the filter housing (10) is sealed by a cover plate.

8. The boiler denitrification device according to claim 7, characterized in that: The bottom of the filter housing (10) is provided with a cone (12), and a valve is provided on the cone (12).

9. The boiler denitrification device according to claim 8, characterized in that: The rotating rod (15) passes through the two sets of filter plates (14) and is rotatably connected to the filter plates (14). One end of the rotating rod (15) is connected to the output shaft of the motor (17). Two brushes (16) are fixedly connected on the rotating rod (15), and the two brushes (16) are respectively attached to the two filter plates (14).

10. The boiler denitrification device according to claim 1, characterized in that: The urea pyrolysis device (1) has a pipe seat (4) welded on the pyrolysis air source duct. One end of the hot air duct (2) is provided with an extension sleeve (5). The extension sleeve (5) is inserted into the pipe seat (4) and forms a compression seal with the sealing ring (6) set between the two. The pipe seat (4) and the hot air duct (2) are fastened together by a flange structure to form a detachable airtight connection interface.

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