Dust deposition prevention device for flue of air duct and purging method

Abstract

The invention discloses an air flue dust deposition prevention device and a purging method, and relates to the technical field of thermal power generation equipment maintenance. The device comprises a compressed air main pipe, a branch pipe, a control valve and a hole opening structure, pipelines are arranged in sections at positions where dust is easy to accumulate, purging holes with specific angles are designed, and timing and staggered purging logic is matched, so that dust accumulated in an air duct and a flue is efficiently removed. The problems that the equipment resistance is increased, the service life is shortened and the like due to dust accumulation can be avoided, and the device is suitable for various balance air ducts and low-flow-speed flues and has the advantages of being simple in structure, high in purging efficiency and low in operation cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal power plant maintenance, and particularly relates to a wind channel and flue ash deposition prevention device and a blowing method, which is suitable for ash removal operation of various airflow channels prone to ash deposition. BACKGROUND

[0002] During the operation of a boiler in a thermal power plant, the ash deposition in the wind channel and the flue has been a key factor affecting the efficiency and service life of the equipment. In particular, at the bottom of the secondary air box of the lower two layers of the boiler, the heat secondary air communication channel and other parts, due to the low flow rate of the flue gas and the complex airflow direction, the ash deposition is prone to occur. The ash deposition not only increases the resistance of the wind channel and reduces the thermal efficiency of the boiler, but also causes the local wear of the equipment to be aggravated, and even causes the expansion joint of the secondary air box to be prematurely aged and failed due to uneven stress.

[0003] In the prior art, the artificial ash removal or steam blowing is mainly used to solve the problem of ash deposition. The artificial ash removal needs to be performed when the unit is shut down, which not only has high labor intensity and high maintenance cost, but also affects the continuous operation time of the unit. Although the steam blowing can be operated when the unit is running, the steam is easy to condense into water in the wind channel, which causes the ash deposition to be hardened and caked, and thus the ash removal difficulty is increased. In addition, the pipeline arrangement of the traditional blowing device is unreasonable, the blowing coverage is limited, and the ash deposition in some dead angles cannot be effectively removed, so that the ash removal effect is not ideal.

[0004] Therefore, there is an urgent need in the art for an ash deposition prevention technical solution which can realize efficient ash removal, comprehensive coverage, no damage to the equipment and low operation cost when the unit is running. SUMMARY

[0005] In view of the above defects of the prior art, the technical problem to be solved by the present application is how to provide a device and a method which are simple in structure, high in blowing efficiency and capable of continuously removing the ash deposition when the unit is running, so as to solve the problems of incomplete ash removal, high maintenance cost and large equipment damage in the prior art.

[0006] To achieve the above objectives, the present invention provides a dust prevention device for air ducts and flues, comprising a compressed air main pipe, a control valve, branch pipes, and a sealing component; one end of the compressed air main pipe is connected to a compressed air source, and the other end extends to the vicinity of the air duct or flue; the control valve is located on the side of the compressed air main pipe near the air duct or flue, and is used to control the total purge air volume; one end of the branch pipe is connected to the compressed air main pipe, and the other end passes through the side panel of the air duct or flue and extends into its interior, with the extension length adapted to the width of the air duct or flue; the sealing component is located at the end of the branch pipe located inside the air duct or flue; multiple purge holes are opened on the section of the branch pipe located inside the air duct or flue, and the opening direction of the purge holes is consistent with the airflow direction in the air duct or flue and inclined downward at a predetermined angle; the branch pipes are arranged on the compressed air main pipe at predetermined intervals, and the position of the branch pipe passing through the side panel of the air duct or flue is at a predetermined height from the bottom plate of the air duct or flue.

[0007] Furthermore, the air duct or flue includes a boiler secondary air box, a hot secondary air connecting air duct, a balancing air duct, and a flue with a low flue gas velocity. The pipeline layout parameters can be adjusted according to the structural characteristics of different channels.

[0008] Furthermore, the compressed air main pipe and the branch pipe are connected by welding. The welding joint adopts a sealing process of argon arc welding for the root and electric arc welding for the cover to ensure the connection strength and airtightness under high temperature and high pressure environment.

[0009] Furthermore, the purge holes are arranged at uniform intervals along the length of the branch pipe, and the spacing between adjacent purge holes is adapted to the extension length of the branch pipe to achieve full coverage purging of the cross-section of the air duct or flue.

[0010] Furthermore, the predetermined angle is 15°-90°. This angle design allows the blowing airflow to act simultaneously on the dust accumulated at the bottom of the air duct and the dust attached to the side wall, thereby improving the dust removal efficiency.

[0011] Furthermore, the predetermined spacing is 0.5m to 3m, and this arrangement density ensures that the purging range of adjacent branch pipes does not overlap and has no dead angles.

[0012] Furthermore, the predetermined height is 100mm-500mm. This height allows the blow hole to avoid the protruding structure at the bottom of the air duct, while ensuring that the airflow can directly impact the dust accumulation area.

[0013] A method for cleaning and purging dust from air ducts and flues based on the above-mentioned device includes the following steps:

[0014] Step 1: Check the pressure of the compressed air main pipe and the sealing condition of the branch pipes to ensure that the purging conditions are met;

[0015] Step 2: Open the control valve to allow compressed air to enter the branch pipe through the main pipe and be injected into the air duct or flue through the purge hole;

[0016] Step 3: Control the duration of a single purging session and the number of purging sessions per day. The time interval between two purging operations is a predetermined cycle.

[0017] Step 4: When purging multiple air ducts or flues, purge them one by one to avoid opening multiple control valves at the same time.

[0018] Furthermore, in step 1, the pressure of the compressed air main pipe is not lower than the predetermined pressure value to ensure that the purging airflow has sufficient impact force; at the same time, check the seal between the branch pipe and the side panel of the air duct or flue, and if air leakage is found, repair welding or sealant filling is used.

[0019] Furthermore, in step 2, the flow velocity of compressed air in the branch pipe is within a predetermined velocity range. This velocity enables the airflow ejected from the purge hole to form a high-speed jet, effectively dispersing the accumulated dust.

[0020] Furthermore, in step 3, the blowing is performed twice a day, with each blowing session lasting 15 to 20 minutes, and the time interval between the two operations is 6 to 10 hours. This frequency can prevent the dust from re-accumulating in a short period of time.

[0021] Furthermore, in step 4, the purging interval between two adjacent air ducts or flues shall not be less than 30 minutes, so as to avoid the purging effect being affected by the pressure fluctuation of the compressed air source.

[0022] The technical effects of this invention are as follows:

[0023] Comprehensive purging coverage: By opening oblique purging holes at specific intervals on the branch pipes, combined with the uniform arrangement of the branch pipes along the air duct, it is possible to achieve all-round purging of the bottom and side walls of the air duct, effectively removing dust dead corners that are difficult to cover by traditional devices.

[0024] High dust removal efficiency: Compressed air is used as the blowing medium. The airflow is high-speed and dry, which can not only efficiently remove accumulated dust, but also avoid the problem of dust hardening caused by steam blowing.

[0025] Minimal equipment damage: Steel pipes have excellent temperature resistance and corrosion resistance. Combined with reasonable welding technology, they can adapt to the high-temperature environment of boiler air ducts and reduce wear on the inner wall of the air ducts. At the same time, the staggered purging method avoids the problem of insufficient compressed air volume and ensures the stability of the purging effect.

[0026] Low operating costs: The existing compressed air system of the power plant is used as the air source, and there is no need to add additional steam generating equipment. The timed automatic purging can reduce manual intervention and reduce maintenance costs.

[0027] Wide range of applications: It is not only suitable for large air boxes and connecting air ducts of coal-fired units, but can also be extended to other balanced air ducts and low-velocity flues that are prone to ash accumulation, and has strong versatility.

[0028] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0029] Figure 1 This is a diagram showing the compressed air pipeline layout of a preferred embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the branch pipe opening in a preferred embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the opening direction of the purge hole in a preferred embodiment of the present invention.

[0032] Explanation of markings in the diagram:

[0033] 1-Compressed air main pipe; 2-Manual ball valve; 3-Branch pipe; 4-Sealing component; 5-Air duct or flue; 6-Purge port. Detailed Implementation

[0034] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0035] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0036] Example 1: Anti-ash accumulation device for secondary air box of newly built 1,000 MW boiler and its application

[0037] This embodiment is applied to the bottom two secondary air boxes of a newly built 1,000 MW coal-fired boiler. Due to the low flue gas velocity (about 5 m / s), the ash accumulation at the bottom of this area can reach 150 mm per month, which seriously affects the efficiency of secondary air distribution.

[0038] Device structure:

[0039] Compressed air main pipe (1): The pipe is matched with the existing compressed air system of the power plant. The material is selected as heat-resistant and corrosion-resistant steel. The length is determined according to the position of the secondary air box. It is laid and fixed along the platform support to ensure that the pipe is not drooping or deformed.

[0040] Control valve (2): Select a manual ball valve with a nominal diameter that matches the main pipe and install it on the horizontal section of the main pipe near the secondary air box for easy control by the operator.

[0041] Branch pipe (3): The material is the same as the main pipe, and the length is adapted to the width of the secondary air box (2m). It is connected to the main pipe by welding. The welding joint is argon arc welding for the root (welding current 120-150A) and electric arc welding for the cover (welding current 180-220A). After welding, a penetration test is performed to ensure that there is no leakage. The branch pipe is arranged at a spacing of 2.5m on the main pipe. A total of 8 branch pipes are set up, covering the entire length of the secondary air box of 20m.

[0042] Sealing component (4): Made of 5mm thick steel plate, welded to the end of the branch pipe to seal and prevent compressed air from leaking from the end;

[0043] Purge holes (6): are opened on the pipe section of the branch pipe located inside the secondary air box. The hole diameter is determined according to the airflow calculation. The distance between adjacent holes is 200mm. The opening direction is consistent with the airflow direction (from left to right) in the secondary air box and is inclined downward at 45°. Ten purge holes are opened on each branch pipe to form staggered purge areas.

[0044] Installation height: The branch pipe should pass through the side panel of the secondary air box at a distance of 350mm from the bottom of the box, avoiding the bottom support structure.

[0045] Purging method:

[0046] Pressure check: Before purging at 8:00 AM and 8:00 PM every day, check the pressure gauge on the main pipe to confirm that the compressed air pressure is not lower than 0.6 MPa. If the pressure is insufficient, start the standby air compressor.

[0047] Sealing inspection: Regularly (once a week) inspect the weld between the branch pipe and the side panel of the secondary air box. Use the soapy water method to check for leaks. If bubbles are found, mark them and arrange for repair welding.

[0048] Purging operation: Open the control valve and adjust the valve opening to stabilize the airflow velocity in the branch pipe at 22 m / s (monitored by a flow meter). Each purging session lasts 18 minutes.

[0049] Performance monitoring: Observe the dust removal status through the observation hole on the top of the secondary air box, and record the changes in dust thickness during regular (once a month) shutdown inspections.

[0050] Application effect:

[0051] After the application of this embodiment, the thickness of the ash accumulation at the bottom of the secondary air box is reduced to 8mm per month, the secondary air resistance coefficient is reduced by 23%, the number of unplanned shutdowns caused by ash accumulation is zero, and the service life of the secondary air box expansion joint is extended from 18 months to 36 months.

[0052] Example 2: Anti-dust accumulation device for hot secondary air connecting duct and its application

[0053] This embodiment is applied to the secondary hot air connecting duct of a power plant. The duct is horizontally arranged, 50m long, and has a rectangular cross-section (3m wide × 2m high). Due to the airflow turning, the local flow velocity is low (about 6m / s), and the side walls are prone to dust accumulation.

[0054] Device structure:

[0055] Compressed air main pipe (1): laid along the outer platform of the air duct, using the same material as in Example 1, with a pressure gauge and control valve installed at the end;

[0056] Branch pipe (3): The length is adapted to the width of the air duct (3m), the arrangement spacing is 2m (25 in total), and it is welded to the main pipe. The welding process is the same as in Example 1.

[0057] Purge hole (6): The hole diameter is the same as in Example 1, the spacing between adjacent holes is 200mm, the opening direction is the same as the airflow direction in the duct and 90° downward, and 15 purge holes are opened in each branch pipe to cover the full width of the duct.

[0058] Plug (4): Uses a solid plug made of the same material as the branch pipe. After threaded connection, it is welded and sealed, which facilitates disassembly and maintenance in the later stage.

[0059] Purging method:

[0060] Purging cycle: Purging once at 10:00 AM and once at 6:00 PM daily, staggered from the secondary air box purging (with an interval of more than 2 hours) to avoid conflict with compressed air usage;

[0061] Flow rate control: The airflow velocity in the branch pipe is adjusted to 20m / s by controlling the valve opening, and a single purging lasts for 20 minutes;

[0062] Staggered operation: Since the connecting air duct is divided into two sections, A and B (each 25m), a segmented purging method is adopted. First, purge section A for 18 minutes, close the control valve of section A, and after a 30-minute interval, purge section B for 18 minutes.

[0063] Data recording: Record the pressure difference between the inlet and outlet of the air duct after each purging (using a differential pressure gauge), compare the pressure difference changes before and after purging, and evaluate the dust removal effect.

[0064] Application effect:

[0065] After application, the thickness of dust accumulation on the side wall of the connecting air duct decreased from 120mm per month to 10mm per month, the pressure difference between the air duct inlet and outlet stabilized within ±5% of the design value, the uniformity of the temperature distribution of the hot secondary air improved by 15%, and the annual labor cost saved due to dust cleaning was approximately 80,000 yuan.

[0066] Example 3: Low-flow-rate flue dust prevention device and its application

[0067] This embodiment is applied to a low-velocity flue gas duct at the tail end of a power plant (flue gas velocity of about 4m / s). The flue gas duct is arranged vertically and is 20m high. The accumulation of ash on the inner wall can easily reduce the flue gas flow area and affect the boiler exhaust temperature.

[0068] Device structure:

[0069] Compressed air main pipe (1): fixed along the ladder support on the outside of the flue, made of high temperature resistant steel (suitable for flue outer wall temperature of 150℃).

[0070] Branch pipe (3): Arranged along the height of the flue, with a spacing of 3m (7 in total), and the length is adapted to the inner diameter of the flue (4m), and it enters horizontally from the side of the flue;

[0071] Purge hole (6): The opening direction is consistent with the flue gas flow direction (vertically upward) and 15° downward, that is, the purging hole faces the bottom of the flue to impact the bottom ash. The distance between adjacent holes is 200mm, and 20 purging holes are opened on each branch pipe.

[0072] Control valve (2): High temperature resistant ball valve is used and installed on the main pipe near the branch pipe for easy operation in high temperature environment.

[0073] Purging method:

[0074] Purging cycle: Once a day (at 2 pm), each purging session lasts 25 minutes. Because the dust accumulation in the flue is relatively slow, the number of purging sessions is reduced to save gas.

[0075] Pressure regulation: Considering the influence of flue height, the compressed air main pipe pressure is maintained at 0.7MPa to ensure the purging force of the top branch pipe;

[0076] Safety measures: Before purging, confirm that there are no maintenance personnel in the flue and close the observation hole to prevent the blown-up ash from overflowing;

[0077] Effect evaluation: By comparing the changes in dust concentration before and after purging using a dust concentration monitor at the flue outlet, the effect of dust removal can be indirectly evaluated.

[0078] Application effect:

[0079] After application, the flue gas temperature decreased by 8°C, the boiler thermal efficiency increased by 0.5%, approximately 500 tons of standard coal were saved annually, and the corrosion rate of the flue inner wall decreased by 10% (due to the reduction of localized corrosion caused by ash accumulation).

[0080] Example 4: Optimization of Multi-Region Joint Purging Control Logic

[0081] This embodiment addresses the issue of ash accumulation in multiple areas of a power plant, including secondary air boxes, connecting air ducts, and low-velocity flues. It optimizes the purging control logic to avoid conflicts in compressed air resources.

[0082] Control methods:

[0083] Time planning: Develop a daily purging schedule, including secondary air boxes (8:00 AM and 8:00 PM), connecting air ducts (10:00 AM and 6:00 PM), and low-velocity flues (2:00 PM), with a purging interval of no less than 2 hours between each area;

[0084] Pressure linkage: A pressure sensor is installed on the main compressed air pipe. When the pressure is lower than 0.5MPa, the current purging will be automatically stopped to prioritize the protection of important air-consuming equipment of the unit. Purging will be restarted after the pressure is restored.

[0085] Priority settings: Secondary air box purging has the highest priority (affecting combustion stability), followed by connecting air ducts, and lastly low-velocity flue. If the gas supply is insufficient, it will be executed according to the priority order.

[0086] Automatic recording: The PLC control system records data such as the time, pressure, and duration of each purging cycle, generating monthly reports to facilitate the optimization of purging parameters.

[0087] Application effect:

[0088] After the implementation of multi-area joint purging, the pressure fluctuation of the compressed air system was controlled within ±0.05MPa, the dust removal effect in each area was stable, and there was no problem of incomplete purging due to insufficient air supply. The number of manual interventions was reduced by 60%.

[0089] Example 5: Optimization of Device Materials and Installation Process

[0090] This embodiment optimizes the material and installation process of the device to address the need for preventing ash accumulation in high-temperature environments (such as boiler outlet flue, with a temperature of approximately 300°C).

[0091] Material optimization:

[0092] Compressed air main pipe and branch pipes: made of heat-resistant steel (such as 12Cr1MoV), which can withstand high temperatures below 400℃;

[0093] Control valves: High-temperature resistant pneumatic ball valves are used, with heat insulation layer wrapping, to adapt to the high-temperature environment of the flue outer wall;

[0094] Welding materials: Select high-temperature resistant welding rods (such as E5515-B2) that match the pipe material, and perform high-temperature tempering treatment after welding to eliminate welding stress.

[0095] Installation process:

[0096] A heat-insulating sleeve is installed where the branch pipe enters the flue. The sleeve is welded and sealed to the flue wall to prevent flue gas leakage.

[0097] The welded joints between the main pipe and the branch pipe are wrapped with an insulation layer to reduce heat transfer and thus reduce the temperature rise of the air inside the pipe.

[0098] Perform high-temperature pressure tests on valves and pipelines regularly (once a quarter) to ensure no leakage at 150°C.

[0099] Application effect:

[0100] After being used in a 300℃ flue environment for 6 months, the device showed no deformation or leakage, the purging effect was stable, and the ash removal efficiency remained above 90%, proving that the invention can adapt to high-temperature working conditions.

[0101] Example 6: Integrated Innovation of Intelligent Purge Control Module

[0102] Based on the aforementioned embodiments 1-3, an intelligent purging control module is added. This module includes:

[0103] Dust concentration sensor: A laser dust concentration sensor is installed at a key location inside the air duct or flue to monitor changes in dust content in the airflow in real time. When the concentration exceeds a preset threshold (such as 20mg / m³), the purging program is automatically triggered, replacing the traditional timed purging mode.

[0104] PLC intelligent controller: It is linked with sensors and control valves and can dynamically adjust the purging time (5-30 minutes adaptive) and interval cycle according to the ash accumulation rate of different areas. It also has data storage function and can generate ash accumulation trend curves to help maintenance personnel predict ash accumulation risks.

[0105] Remote control interface: Through integration with the power plant's DCS system, it enables remote monitoring and manual intervention of the purging status, and supports alarm reminders via mobile APP (such as in case of abnormal pressure or sensor failure).

[0106] The intelligent control algorithm is based on a PLC controller. It takes real-time dust concentration as the core input and combines historical dust accumulation data, compressed air pressure, and unit operating status to dynamically generate a purging strategy. The specific process is as follows:

[0107] 1. Data Acquisition and Preprocessing

[0108] Real-time parameter acquisition: The dust concentration value (denoted as C) in the air duct / flue is obtained through a laser dust concentration sensor (sampling frequency 1 time / minute). 实时 The compressed air main pipe pressure (P) is collected by a pressure sensor. 实时 ); The unit's DCS system synchronously acquires operating parameters such as boiler load (L, unit %) and flue gas velocity (V, unit m / s).

[0109] Data filtering: A moving average method (window size 5 minutes) is used to filter C in real time to eliminate transient interference (such as concentration abrupt changes caused by airflow fluctuations), resulting in a smoothed concentration value C. 滤波 .

[0110] 2. Determining the conditions for starting the purging process

[0111] Base threshold trigger: When C 滤波 When the value is greater than or equal to the preset start-up threshold (e.g., 20 mg / m³), it enters the start-up candidate state.

[0112] Trend prediction correction: based on the past 1 hour C 滤波 The rate of change (ΔC / Δt) determines the rate of dust accumulation.

[0113] If ΔC / Δt > 0.5 mg / (m³·h) (rapid ash accumulation), the start-up is triggered directly;

[0114] If 0.1 mg / (m³·h) ≤ ΔC / Δt ≤ 0.5 mg / (m³·h) (slow ash accumulation), detect again after a 30-minute delay. If C filter ≥ start threshold is still satisfied, then start.

[0115] If ΔC / Δt < 0.1 mg / (m³·h) (trace amount of ash), do not start the process and continue monitoring.

[0116] Operation status linkage: If the boiler load L≥80% (high load period), the start threshold will automatically decrease by 10% (e.g., to 18mg / m³) to prioritize smooth airflow under high load; if L<50% (low load), the start threshold will increase by 10% (e.g., to 22mg / m³) to reduce unnecessary gas consumption.

[0117] 3. Dynamic adjustment of purging parameters

[0118] Calculation of purging duration (T):

[0119] T=T 基准 ×(C 滤波 / C 基准 )×(V 基准 / V 实时 )

[0120] Where T is the default duration (15 minutes), and C... 基准 For the design concentration (20 mg / m³), V 基准 Design flow velocity (5 m / s); V 实时 This is the real-time flow rate.

[0121] Example: If C 滤波 =30mg / m³ (higher than the baseline), V 实时=4m / s (lower than the baseline), then T=15×(30 / 20)×(5 / 4)=28.125 minutes (rounded up to 29 minutes), ensuring sufficient purging of the high concentration, low flow rate area.

[0122] Interval period (ΔT) setting:

[0123] A dust accumulation model was constructed based on historical data, recording C under different working conditions. 滤波 From the lowest value after purging (C) 最低 The time it takes for the temperature to rise back to the startup threshold is used to set ΔT to 80% of that time (with a buffer reserved).

[0124] Example: Historical data shows that a certain region has changed from C 最低 =It takes an average of 10 hours for the concentration of 5mg / m³ to rise to 20mg / m³, so ΔT = 8 hours.

[0125] 4. Optimization of Anomaly Handling and Feedback

[0126] Insufficient gas pressure: If P 实时 If the pressure is less than 0.5 MPa (minimum working pressure), pause the current purging process, trigger the standby air compressor start signal, and wait for P... 实时 Restart after pressure reaches ≥0.6MPa, and T will automatically increase by 20% after restarting (to compensate for insufficient pressure).

[0127] Sensor failure: If the sensor has no data or abnormal data for 10 consecutive minutes, it will automatically switch to timed mode (using the strategy of twice a day with an interval of 8-10 hours in Example 1), and trigger an alarm to remind maintenance personnel to perform maintenance.

[0128] Effect feedback and correction: Record C within 30 minutes after each purging. 最低 If C 最低 Before purging C 滤波 If the difference is <5mg / m³ (poor purging effect), then T will be used during the next purging. 基准 Automatically increase by 10% until the difference is ≥8mg / m³, then revert to the default value.

[0129] This invention effectively solves the problem of ash accumulation in air ducts and flues by rationally designing the pipeline layout, opening angle, and purging logic of the anti-ash accumulation device. Multiple embodiments have verified that this invention is not only applicable to the secondary air boxes and connecting air ducts of newly built megawatt-class units, but can also be extended to various low-velocity flues, demonstrating significant economic benefits and practical value. Those skilled in the art can adjust the device parameters and purging methods according to specific application scenarios, but all core technical solutions should fall within the protection scope defined by the claims of this invention.

[0130] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A dust accumulation prevention device for air ducts and flues, characterized in that, Includes compressed air main pipe (1), control valve (2), branch pipe (3) and sealing component (4); One end of the compressed air main pipe (1) is connected to a compressed air source, and the other end extends to the vicinity of the air duct or flue (5); the control valve (2) is located on the side of the compressed air main pipe (1) near the air duct or flue (5) to control the total purging air volume; one end of the branch pipe (3) is connected to the compressed air main pipe (1), and the other end passes through the side panel of the air duct or flue (5) and extends into its interior, with the extension length adapted to the width of the air duct or flue (5); the sealing element (4) is located on the branch pipe. The pipe (3) is located at the end inside the air duct or flue (5); the branch pipe (3) is provided with multiple purge holes (6) on the pipe section inside the air duct or flue (5), the opening direction of the purge holes (6) is consistent with the airflow direction inside the air duct or flue (5) and is inclined downward at a predetermined angle; the branch pipe (3) is arranged on the compressed air main pipe (1) at a predetermined interval, and the position of the branch pipe (3) passing through the side panel of the air duct or flue (5) is at a predetermined height from the bottom plate of the air duct or flue (5).

2. The apparatus as claimed in claim 1, characterized in that, The air duct or flue (5) includes the boiler secondary air box, the hot secondary air connecting air duct, the balancing air duct, and the flue with a lower flue gas velocity.

3. The apparatus as described in claim 1, characterized in that, The compressed air main pipe (1) and the branch pipe (3) are connected by welding, and the weld is treated with a sealing process.

4. The apparatus as claimed in claim 1, characterized in that, The purge holes (6) are arranged at uniform intervals along the length of the branch pipe (3), and the spacing between adjacent purge holes (6) is adapted to the extension length of the branch pipe (3).

5. The apparatus as claimed in claim 1, characterized in that, The predetermined angle is 15°-90°.

6. The apparatus as claimed in claim 1, characterized in that, The predetermined spacing is 0.5m to 3m.

7. The apparatus as claimed in claim 1, characterized in that, The predetermined height is 100-500mm.

8. A method for cleaning and purging dust accumulation in a flue or duct based on the device described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Check the pressure of the compressed air main pipe (1) and the sealing condition of the branch pipe (3) to ensure that the purging conditions are met; Step 2: Open the control valve (2) to allow compressed air to enter the branch pipe (3) through the main pipe (1) and be injected into the air duct or flue (5) through the purge hole (6); Step 3: Control the duration of a single purging session and the number of purging sessions per day. The time interval between two purging operations is a predetermined cycle. Step 4: When purging multiple air ducts or flues (5), purge them one by one to avoid opening multiple control valves (2) at the same time.

9. The method as described in claim 8, characterized in that, In step 1, the pressure of the compressed air main pipe (1) is not lower than the predetermined pressure value.

10. The method as described in claim 8, characterized in that, In step 2, the flow rate of compressed air in the branch pipe (3) is within a predetermined flow rate range.

11. The method as described in claim 8, characterized in that, In step 3, the purging is performed twice a day, with each purging session lasting 15 to 20 minutes, and the time interval between the two operations is 6 to 10 hours.

12. The method as described in claim 8, characterized in that, In step 4, the purging interval between two adjacent air ducts or flues (5) shall not be less than 30 minutes.

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