A pre-dust removal device for scr flue gas denitration

Abstract

The application relates to the field of flue gas denitration technology and discloses an SCR flue gas denitration pre-dust removal device, which comprises a shell, a filter screen, a mixing chamber and a denitration reactor are sequentially arranged in the shell from an air inlet, a cleaning assembly is arranged in an air inlet section of the shell, the cleaning assembly comprises a brush head and a hydraulic cylinder, the hydraulic cylinder is fixedly connected to an outer wall of the shell through a base and a piston rod of the hydraulic cylinder penetrates the shell, a reducing agent introduction pipe is arranged on a side wall of the mixing chamber and is connected with a reducing agent conveying pipe through flanges, an electrostatic dust removal device is connected with one end of the shell away from the air inlet through an outlet flange, the electrostatic dust removal device comprises a dust removal shell, a plurality of mounting rods and electrode plates are arranged in the dust removal shell, the electrode plates are axially sleeved on the mounting rods and are positioned through fasteners, an electrode assembly is arranged on the electrode plates, a shocking device is arranged on the top of the electrostatic dust removal device, the shocking device comprises a knocking hammer and a rotating shaft, the rotating shaft is fixed to a top plate of the dust removal shell through a support, and the knocking hammer is knocking matched with the mounting rods.

Description

Technical Field

[0001] This application belongs to the technical field of flue gas denitrification, specifically relating to an SCR flue gas denitrification pre-dust removal device. Background Technology

[0002] Currently, most coal-fired power plants in my country have achieved ultra-low emissions, and the vast majority of these plants employ selective catalytic oxidation-reduction (SCR) technology for flue gas denitrification. This involves placing a SCR catalyst between the economizer outlet and the air preheater inlet, allowing NOx from the flue gas to react with injected ammonia under the catalyst's catalytic action, producing N2 and thus reducing NOx emissions. However, a survey of the operational status of denitrification systems in domestic coal-fired power plants reveals that most systems suffer from varying degrees of ash blockage, posing a safety hazard to the safe and stable operation of these plants. The specific hidden dangers manifest in the following three aspects: 1. Fly ash clogs the micropores on the surface of the catalyst in the denitrification system, reducing the reaction rate of NOx in the flue gas of the coal-fired boiler and posing a risk of NOx emissions failing to meet standards; 2. Fly ash clogs the catalyst modules in the denitrification system, reducing the effective flow area of ​​the flue gas in the denitrification system, increasing the flue gas velocity, causing local scouring and wear of the catalyst by the dust-laden flue gas, and reducing the service life of the catalyst in the denitrification system; 3. Fly ash clogs the catalyst modules in the denitrification system, increasing the resistance of the denitrification system itself, increasing the power consumption of the induced draft fan, and increasing the operating cost of the coal-fired boiler.

[0003] Currently, coal-fired power plants have adopted two methods to address the problem of catalyst blockage in the denitrification system caused by fly ash: one is to increase the blowing frequency of steam soot blowers and sonic soot blowers during online operation, but this method cannot cover the dead zones of flue gas in the denitrification system, and some catalyst modules still have blockage problems; the other is to manually clean the ash while the unit is shut down, but this method has limited effectiveness, and the catalyst becomes blocked again after the unit is restarted for a period of time.

[0004] In recent years, with the continuous rise in domestic coal prices, coal-fired power plants have increasingly adopted high-ash coal as their feed coal to reduce production costs. However, the high-ash flue gas produced by the combustion of high-ash coal has become increasingly harmful to denitrification systems. How to reduce the clogging and scouring of denitrification systems by high-ash flue gas is a problem that urgently needs to be researched and solved by scholars and operators both domestically and internationally. Utility Model Content

[0005] This application provides an SCR flue gas denitrification pre-dust removal device to solve the aforementioned technical problem of denitrification system blockage.

[0006] The technical solution adopted in this application is as follows: A pre-dust removal device for SCR flue gas denitrification includes a shell. Inside the shell, starting from the air inlet, are sequentially arranged a filter screen, a mixing chamber, and a denitrification reactor. A cleaning component is installed in the air inlet section of the shell, including a brush head and a hydraulic cylinder. The hydraulic cylinder is fixed to the outer wall of the shell via a base, and its piston rod passes through the shell. A reducing agent inlet pipe is provided on the side wall of the mixing chamber and connected to a reducing agent delivery pipe via a flange. An electrostatic precipitator is connected to the end of the shell away from the air inlet via an outlet flange. The electrostatic precipitator includes a dust removal shell. Several mounting rods and electrode plates are arranged inside the dust removal shell. The electrode plates are axially mounted along the mounting rods and positioned by fasteners. Electrode assemblies are installed on the electrode plates and are detachably connected to the electrode plates by bolts. A vibration device is provided at the top of the electrostatic precipitator, including a hammer and a rotating shaft. The rotating shaft is fixed to the top plate of the dust removal shell via a support. The hammer engages with the mounting rods in a striking motion.

[0007] Optionally, an actuating blower is installed under the denitrification reactor. The casing of the actuating blower is connected to the side wall of the casing via a flange. The actuating blower is connected to a drive motor. The output shaft of the drive motor is connected to the blower shaft of the actuating blower via a coupling. The drive motor is fixed to the blower support.

[0008] Optionally, the filter screen is a detachable frame-type filter unit. The filter unit is connected to the inner wall of the housing through flange plates, bolts and gaskets. The filter unit contains a screen and is positioned by fasteners. The filter screen has an inspection port along the airflow direction. The inspection port is equipped with a detachable cover plate and is positioned by fasteners.

[0009] Optionally, two rows of reducing agent nozzles are symmetrically arranged inside the mixing chamber. The nozzles are connected to the reducing agent delivery pipe via flanges, and the nozzles are arranged axially in a staggered manner and fixed to the inner wall of the mixing chamber by nozzle brackets.

[0010] Optionally, two sets of guide plates are fixedly installed inside the inner wall of the shell. The guide plates are arranged at a certain angle along the radial direction of the flue gas. The guide plates are several arc-shaped plates. The guide plates are arranged at equal intervals through supports. The supports are fixed to the inner wall of the shell by bolts, and a set gap is maintained between the front edge of the guide plate and the inner wall of the shell.

[0011] Optionally, the vibration device includes a motor mounted on the top plate of the electrostatic precipitator, a small pulley mounted on the motor shaft, the small pulley being connected to a large pulley located on the rotating shaft via a transmission belt, the small pulley being connected to the motor shaft via a key, and a number of striking hammers being axially sleeved on the rotating shaft, the striking hammers being mounted on the rotating shaft via a key.

[0012] Due to the adoption of the above technical solution, the beneficial effects achieved by this application are as follows: 1. Through secondary filtration at the air inlet and mechanical cleaning of the air inlet section wall by a retractable brush head, the amount of coarse particles entering the denitrification reactor is significantly reduced, thus lowering the probability of catalyst surface and module blockage. 2. The reactor inlet section is equipped with a baffle plate and a blower to improve the airflow distribution, increase the uniformity of mixing of flue gas and ammonia, improve denitrification efficiency and reduce local scouring; 3. The electrostatic precipitator is equipped with a knocking and vibration device on the basis of high voltage electrostatic sedimentation. By periodically knocking the mounting rod and electrode plate, the attached particles are shaken off in time and concentrated into the ash hopper, which improves the electrode purification efficiency and extends the maintenance cycle of the electrode assembly. 4. The equipment adopts standardized flanges, quick-installation clamps, and detachable modular electrode assemblies and modular catalyst components, which facilitates on-site maintenance, module replacement, and reduces downtime for maintenance. 5. The multi-level alternative implementation methods and adjustable parameter range provide a means of adaptation to different furnace types and coal types. Attached Figure Description

[0013] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a perspective view of an SCR flue gas denitrification and pre-dust removal device according to this application; Figure 2 This is a cross-sectional view of an SCR flue gas denitrification and pre-dust removal device according to this application; Figure 3 This is a perspective view of the internal components of the mixing cavity in this application; Figure 4 This is a perspective view of the cleaning components in this application; Figure 5 This is a cross-sectional view of the denitrification reactor in this application; Figure 6 This is a three-dimensional view of the oscillation device in this application.

[0014] 1. Shell; 2. Air inlet; 3. Filter screen; 4. Mixing chamber; 5. Denitrification reactor; 6. Cleaning components; 61. Brush head; 62. Hydraulic cylinder; 7. Electrostatic dust removal device; 8. Vibration device; 81. Rotating shaft; 82. Striking hammer; 9. Inlet pipe; 10. Conveying pipe; 11. Dust collector shell; 12. Mounting rod; 13. Electrode plate; 14. Electrode assembly; 15. Actuating fan; 16. Drive motor; 17. Fan support; 18. Cover plate; 19. Nozzle; 20. Guide plate; 21. Motor; 22. Small pulley; 23. Large pulley. Detailed Implementation

[0015] To more clearly illustrate the overall concept of this application, a detailed explanation is provided below with reference to the accompanying drawings.

[0016] Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below. It should be noted that, unless otherwise specified, the embodiments of this application and the features thereof can be combined with each other. Example

[0017] This embodiment provides an SCR flue gas denitrification pre-dust removal device, the structure of which includes a housing 1. From the inlet 2 to the outlet flange, the housing 1 is sequentially equipped with components such as a filter screen 3, a mixing chamber 4, a denitrification reactor 5, and an outlet flange. The filter screen 3, located in the inlet section of the housing 1, is used to intercept and capture large dust particles, preventing these dust particles from entering subsequent denitrification and dust removal stages. After entering through the inlet 2, the flue gas first passes through the filter screen 3, where a large amount of larger dust particles are trapped. A cleaning component 6 is provided inside the inlet section of the housing 1 for cleaning the inner wall of the inlet section. This cleaning component 6 consists of a brush head 61 and a hydraulic cylinder 62, wherein the hydraulic cylinder 62 is fastened to the outer wall of the housing 1 via a base, and the piston rod of the hydraulic cylinder 62 passes through the housing 1 and is connected to the brush head 61. When the cleaning component 6 is turned on, the piston rod of the hydraulic cylinder 62 drives the brush head 61 to sweep the inner wall of the air intake section of the housing 1, removing the dust accumulated on the inner wall of the air intake section of the housing 1, and preventing the flue gas flow rate from decreasing due to the increased resistance caused by the accumulation of dust on the inner wall of the air intake section of the housing 1.

[0018] After passing through filter 3, the flue gas enters the mixing chamber 4 inside the housing 1. A reducing agent inlet pipe 9 is connected to the side wall of the mixing chamber 4 via a flange. The reducing agent enters the mixing chamber 4 through this inlet pipe 9 and is injected into the flue gas flow through nozzle 19. After the reducing agent is fully mixed with the flue gas in the mixing chamber 4, the flue gas enters the denitrification reactor 5. The denitrification reactor 5 is filled with an SCR denitrification catalyst. In this reactor, NOx reacts chemically with the reducing agent at a suitable temperature, reducing NOx to nitrogen and water.

[0019] The end of the housing 1 furthest from the air inlet 2 is connected to the electrostatic precipitator 7 via an outlet flange. The electrostatic precipitator 7 includes a dust collection housing 11 and multiple electrode plates 13 installed inside it. The electrode plates 13 are mounted inside the dust collection housing 11 by mounting rods 12 and fixed in predetermined positions by fasteners such as bolts. Each electrode plate 13 is equipped with an electrode assembly 14, which can be removed from the electrode plate 13 by bolts for easy maintenance and replacement. The electrode assembly 14 includes a high-voltage discharge electrode section, which can ionize the flue gas passing between the electrode plates 13, causing dust particles in the flue gas to become charged and adsorbed onto the surface of the electrode plate 13. To remove the dust accumulated on the electrode plates 13, the top of the electrostatic precipitator housing 11 is provided with a vibration device 8, including a hammer 82 and a rotating shaft 81 supporting the hammer 82. The rotating shaft 81 is mounted on the top plate of the electrostatic precipitator housing 11 by a bracket, and the hammer 82 is mounted on the rotating shaft 81 and corresponds to the mounting rod 12 inside the housing 1. When the vibration device 8 is activated, the hammer 82 on the rotating shaft 81 strikes the mounting rod 12, and the vibration generated causes the dust on the electrode plate 13 to be dislodged. In this way, long-term accumulation of dust on the electrode plate 13 can be prevented, reducing the frequency of manual cleaning required by the electrostatic precipitator 7. Example

[0020] Based on Example 1, this example adds an actuator fan 15 to the denitrification reactor 5. The actuator fan 15 is connected to the side wall of the casing 1 via a fan support 17. The actuator fan 15 is equipped with a drive motor 16, which is connected to the main shaft of the actuator fan 15 via a coupling. This actuator fan 15 provides additional power to forcefully pump flue gas through the denitrification reactor 5, overcoming the flow resistance caused by the front-end filter 3 and the catalyst bed. By adding the actuator fan 15, the flow velocity of the flue gas within the equipment can be increased, allowing the flue gas to pass through the SCR catalyst more quickly, thereby maintaining the stability of denitrification and dust removal effects. Example

[0021] Based on the device described in Embodiment 1, this embodiment designs the front-end filter screen 3 as a detachable frame filter unit. This frame filter unit is sealed to the inner wall of the housing 1 via components such as flanges, screws, and gaskets. The frame unit contains a mesh screen as the filter medium to intercept dust particles in the flue gas. The mesh screen is fixed inside the frame unit with screws, ensuring the filter screen 3 remains stable while facilitating its disassembly and replacement without affecting the normal operation of the equipment. The filter unit has an inspection port located on the side of the frame unit where the flue gas flows laterally, equipped with a detachable cover plate 18 and secured with fasteners. Through this inspection port, maintenance personnel can quickly clean or replace the internal mesh screen without interfering with the normal operation of the filter unit, avoiding the hassle of completely disassembling the filter unit. Example

[0022] To ensure more uniform and efficient mixing of flue gas and reducing agent within the mixing chamber 4, this embodiment employs two sets of symmetrically arranged reducing agent nozzles 19. These two sets of nozzles 19 are installed on opposite sides of the mixing chamber 4. Each set of nozzles 19 is connected to the corresponding reducing agent delivery pipe 10 via a flange. The two sets of nozzles 19 are staggered along the axial direction of the mixing chamber 4, forming an alternating spray pattern. This alternating spray pattern avoids uneven concentration caused by overly concentrated reducing agent injection, allowing the reducing agent to be more evenly distributed in the flue gas. The nozzles 19 are fixed to the inner wall by nozzle 19 brackets, ensuring their stable and reliable position and facilitating maintenance and replacement. Example

[0023] In this embodiment, two sets of guide plates 20 are fixedly installed inside the shell 1. Each set of guide plates 20 consists of multiple arc-shaped guide plates 20, which are arranged at a certain angle on the flue gas flow path to guide the flue gas flow. The multiple guide plates 20 are arranged at equal intervals by a support. To reduce the resistance of the guide plates 20 to the airflow, a certain gap is left between the front edge of the guide plate 20 and the inner wall of the shell 1, ensuring that some flue gas can bypass the guide plate 20 through the gap. The arrangement of the guide plates 20 makes the flue gas evenly distributed in the cross section, helping to reduce the accumulation of local dust in the denitrification reactor 5. Example

[0024] In this embodiment, the oscillation device 8 of the electrostatic precipitator 7 is driven by a motor 21 as the power source to drive the striking hammers 82. The motor 21 is mounted on the top of the dust collector housing 11. A small pulley 22 is mounted on the shaft of the motor 21 and is fixed to the shaft of the motor 21 by a key. It is connected to a large pulley 23 on the rotating shaft 81 of the oscillation device 8 via a transmission belt. Multiple striking hammers 82 are mounted axially on the rotating shaft 81, and each striking hammer 82 is fixed to the rotating shaft 81 by a key. After the motor 21 is started, the small pulley 22 drives the transmission belt to rotate, thereby driving the large pulley 23 and the rotating shaft 81 to rotate synchronously. As the rotating shaft 81 rotates, the multiple striking hammers 82 strike the mounting rod 12 inside the electrostatic precipitator 7 one by one in sequence, thereby achieving uniform vibration of the electrode plate 13. The oscillation device 8 driven by the motor 21 does not require manual control of the striking, and can automatically vibrate and clean the electrode plate 13 according to a set period, ensuring the long-term stable operation of the electrostatic precipitator 7.

[0025] Working principle: Flue gas enters the housing 1 through the inlet 2 of the device. It first passes through the filter screen 3 to intercept larger particles. If necessary, the brush head 61, controlled by the hydraulic cylinder 62, extends to mechanically clean the wall of the inlet section of the housing 1 to remove accumulated dust. The flue gas enters the mixing chamber 4 and is fully mixed with the reducing agent introduced through the nozzle 19 before entering the denitrification reactor 5 filled with catalyst. A selective catalytic reduction reaction occurs on the catalyst surface to generate nitrogen and water. The denitrified flue gas enters the electrostatic precipitator 7 connected to its outlet flange. The electrode assembly 14 ionizes the flue gas particles and causes the charged particles to migrate and deposit on the electrode assembly 14 under the action of the electric field force. The oscillating device 8 at the top of the electrostatic precipitator 7 drives the small pulley 22 through the motor 21, which in turn drives the large pulley 23 on the rotating shaft 81 to rotate, driving the hammer 82 to periodically strike the mounting rod 12, shaking the dust particles deposited on the electrode assembly 14 and the electrode plate 13 to fall into the lower ash hopper. The ash hopper discharges ash periodically or online, thereby completing the continuous collection and emission of particulate matter. For any parts not mentioned in this application, existing technologies may be used or referenced.

[0026] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0027] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A pre-dust removal device for SCR flue gas denitrification, comprising a housing (1), characterized in that: The housing (1) is provided with a filter screen (3), a mixing chamber (4), and a denitrification reactor (5) in sequence from the air inlet (2). A cleaning component (6) is provided in the air inlet section of the housing (1). The cleaning component (6) includes a brush head (61) and a hydraulic cylinder (62). The hydraulic cylinder (62) is fixed to the outer wall of the housing (1) by a base and its piston rod passes through the housing (1). The side wall of the mixing chamber (4) is provided with a reducing agent inlet pipe (9) and is connected to the reducing agent delivery pipe (10) through a flange. An electrostatic dust removal device (7) is connected to the end of the housing (1) away from the air inlet (2) through an outlet flange. The electrostatic dust removal device (7) includes a dust removal... The dust removal housing (11) has several mounting rods (12) and electrode plates (13) arranged inside. The electrode plates (13) are axially sleeved along the mounting rods (12) and positioned by fasteners. The electrode plates (13) are provided with electrode assemblies (14). The electrode assemblies (14) are detachably connected to the electrode plates (13) by bolts. The top of the electrostatic dust removal device (7) is provided with a vibration device (8). The vibration device (8) includes a hammer (82) and a rotating shaft (81). The rotating shaft (81) is fixed to the top plate of the dust removal housing (11) by a support. The hammer (82) and the mounting rods (12) engage in a striking cooperation.

2. The dust removal device according to claim 1, characterized in that: A drive fan (15) is installed under the denitrification reactor (5). The casing of the drive fan (15) is connected to the side wall of the shell (1) through a flange. The drive fan (15) is connected to a drive motor (16). The output shaft of the drive motor (16) is connected to the fan shaft of the drive fan (15) through a coupling. The drive motor (16) is fixed to the fan support (17).

3. The dust removal device according to claim 1, characterized in that: The filter screen (3) is a detachable frame-type filter unit. The filter unit is connected to the inner wall of the housing (1) through a flange plate, bolts and a sealing gasket. The filter unit is equipped with a screen and is positioned by fasteners. The filter screen (3) has an inspection port along the airflow direction. The inspection port is equipped with a detachable cover plate (18) and is positioned by fasteners.

4. The dust removal device according to claim 1, characterized in that: The mixing chamber (4) is symmetrically provided with two rows of reducing agent nozzles (19). The nozzles (19) are connected to the reducing agent delivery pipe (10) through flanges. The nozzles (19) are arranged axially in an alternating manner and fixed to the inner wall of the mixing chamber (4) by nozzle brackets.

5. The dust removal device according to claim 1, characterized in that: Two sets of guide plates (20) are fixedly installed on the inner wall of the housing (1). The guide plates (20) are arranged at a certain angle along the radial direction of the flue gas. The guide plates (20) are several arc-shaped plates. The guide plates (20) are arranged at equal intervals through supports. The supports are fixed to the inner wall of the housing (1) by bolts. The flow-facing edge of the guide plate (20) and the inner wall of the housing (1) maintain a set gap.

6. The dust removal device according to claim 1, characterized in that: The oscillation device (8) includes a motor (21) installed on the top plate of the electrostatic dust removal device (7), a small pulley (22) installed on the shaft of the motor (21), the small pulley (22) being connected to a large pulley (23) located on the rotating shaft (81) via a transmission belt, the small pulley (22) being connected to the shaft of the motor (21) via a key, and a plurality of striking hammers (82) being axially sleeved on the rotating shaft (81), the striking hammers (82) being installed on the rotating shaft (81) via a key.

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