Dual-mode air preheater flushing system and flushing method

Abstract

The invention relates to a dual-mode air preheater flushing system which comprises an air preheater, the air preheater comprises a shell and a heat transfer element, the heat transfer element is rotationally arranged in the shell, and the dual-mode air preheater flushing system further comprises a state detection module, a flushing structure and an ash outlet; the flushing structure comprises an annular rail, a straight guide rail and a flushing pipe with a high-pressure bundling nozzle, the annular rail is arranged around the bottom surface of the heat transfer element, the flushing pipe realizes radial movement through a linear driving mechanism arranged on the straight guide rail, and the bottom of the straight guide rail is in sliding connection with the annular rail; the dual-mode air preheater flushing system integrates an operation flushing mode and a shutdown flushing mode. The state detection module switches flushing modes by monitoring the state of a mandrel of a heat transfer element, an ash outlet is formed in the bottom of the shell and provided with an ash discharging valve capable of being opened and closed, and coordination of dynamic flushing in operation and precise positioning deep flushing after shutdown can be achieved.

Description

Technical Field

[0001] The present invention relates to a dual-mode air preheater flushing system and a flushing method, belonging to the technical field of air preheater flushing. Background Art

[0002] During the operation of traditional air preheaters, the heat transfer elements are prone to being blocked due to the deposition of ash in the flue gas, resulting in a decrease in heat transfer efficiency and an increase in energy consumption. Most existing flushing systems adopt a single mode and can only perform surface flushing during equipment operation. For example, the air preheater flushing system disclosed in CN105241298A. When the air preheater is in use, the spray nozzles of the flushing pipes can move. Through this movement, the heat transfer elements can be flushed more comprehensively, and there is no need to stop the machine during the cleaning process, that is, cleaning can be achieved without affecting normal use. However, it is difficult to coordinate the rotation speed of the heat transfer elements of the air preheater and the linear movement speed of the flushing pipes, and it is difficult to completely remove deep-layer ash deposits; while the shutdown flushing often relies on manual positioning of the blocked area, there are problems such as a large flushing blind area, long time consumption, and rough water pressure control. Some equipment adopts a fixed nozzle layout, which cannot adapt to the dynamic rotation working condition of the heat transfer elements, resulting in insufficient flushing coverage. In addition, there is a lack of intelligent blockage monitoring means, the flushing pressure does not match the ash deposition degree, which is likely to cause waste of water resources or incomplete flushing, and frequent shutdown for cleaning further affects the operating economy of the unit. Summary of the Invention

[0003] In order to solve the above problems existing in the prior art, the present invention provides a dual-mode air preheater flushing system and a flushing method, which can realize the coordination of dynamic flushing during operation to maintain the basic cleanliness and precise positioning and deep flushing after shutdown.

[0004] The technical solution of the present invention is as follows:

[0005] A dual-mode air preheater flushing system includes an air preheater. The air preheater includes a housing and heat transfer elements. The heat transfer elements are rotatably arranged in the housing. It further includes a state detection module, a flushing structure, and an ash outlet; the flushing structure includes an annular track, a straight guide rail, and a flushing pipe with a high-pressure cluster nozzle. The annular track is arranged around the bottom surface of the heat transfer elements. The flushing pipe realizes radial movement through a linear driving mechanism provided on the straight guide rail. The bottom of the straight guide rail is slidably connected to the annular track; the dual-mode air preheater flushing system is integrated with an operation flushing mode and a shutdown flushing mode. The operation flushing mode includes using the flushing pipe to reciprocate along the straight guide rail for radial flushing. The shutdown flushing mode includes an annular driving mechanism configured on the annular track. The flushing pipe can be circumferentially rotated and positioned along the annular track, and hierarchical flushing is implemented; the state detection module switches the flushing mode by monitoring the state of the core shaft of the heat transfer elements. The ash outlet is arranged at the bottom of the housing and is configured with an openable and closable ash discharge valve.

[0006] Among them, the state detection module includes a rotational speed sensor, a current detection unit, and a control module. The rotational speed sensor and the current detection unit judge whether the air preheater is in an operating or stopped state by monitoring the rotational speed and working current of the heat transfer element mandrel; the control module triggers the corresponding flushing mode.

[0007] Among them, the linear drive mechanism includes a servo motor and a gear-rack transmission assembly. The gear-rack transmission assembly includes a servo motor, a driving gear, a rack, and a guiding base. The rack is fixed to the upper surface of the straight guide rail by bolts. The guiding base is slidably connected to the straight guide rail through a slider. The top of the guiding base is rigidly connected to the flushing pipe through a flushing pipe mounting bracket; the servo motor is vertically installed on the side of the guiding base, and the output shaft of the servo motor penetrates the guiding base and is connected to the driving gear through a coupling.

[0008] Among them, the ring drive mechanism includes a stepping motor, a ring gear, and an orbital connection substrate. The ring gear is fixedly installed on the inner side of the ring track, and the tooth surface of the ring gear faces inwards; the orbital connection substrate has an L-shaped structure. The vertical side of the orbital connection substrate is rigidly connected to the bottom of the straight guide rail by bolts. The horizontal side of the orbital connection substrate extends below the ring gear. The stepping motor is installed upside down on the lower surface of the horizontal side of the orbital connection substrate. The output shaft of the stepping motor penetrates the orbital connection substrate upwards and is connected with a planetary gear, and the planetary gear meshes with the ring gear; the straight guide rail forms a slidable connection with the ring track through the orbital connection substrate.

[0009] Among them, the stopped flushing mode includes a blockage monitoring system. The blockage monitoring system includes an axial monitoring unit and a radial detection unit. The axial monitoring unit includes infrared thermal imagers evenly distributed along the axis of the air preheater at equal intervals. The radial detection unit includes differential pressure sensors arranged in a circumferential array on the air preheater; the infrared thermal imagers are used to detect abnormal surface temperature areas caused by uneven heat dissipation due to ash accumulation, and the differential pressure sensors are used to measure the pressure difference between the inlet and outlet when air flows through the heat transfer element to provide dynamic air flow resistance data; the data provided by the axial monitoring unit and the radial detection unit are fused to generate a blockage degree thermal map and mark the coordinates of the unflushed area; after the stopped flushing mode is started, the blockage monitoring system locates the unflushed area and synchronously sends it to the linear drive mechanism and the ring drive mechanism, and the flushing pipe is controlled to move to the target position for hierarchical flushing.

[0010] Among them, the straight guide rail and the ring track form a linkage mechanism through the orbital connection substrate. In the stopped mode, the flushing pipe first rotates along the ring track to the target angle, and then moves radially along the straight guide rail to the specified radius to achieve precise positioning flushing in the polar coordinate system.

[0011] Among them, it also includes a pressure regulation module for realizing hierarchical flushing. The pressure regulation module is connected in series on the water supply pipeline between the flushing pipe and an external high-pressure water source. The pressure regulation module includes a pressure sensor, an electric control valve and a controller. The pressure sensor is used to monitor the water pressure at the nozzle in real time and feed the data back to the controller. The controller dynamically adjusts the opening degree of the electric control valve according to the blockage degree heat map provided by the blockage monitoring system.

[0012] Among them, the pressure of the high-pressure cluster nozzle is divided into three gears: the pressure is 2-4 MPa, which is used for the area where the blockage degree ≤ 30%; the pressure is 5-7 MPa for the area where 30% ≤ blockage degree ≤ 70%; the pressure is 8-10 MPa for the area where the blockage degree ≥ 70%.

[0013] An air preheater flushing method includes a dual-mode air preheater flushing system, which is characterized by including the following steps:

[0014] S1: The state detection module is used to monitor the rotation speed and working current of the heat transfer element mandrel in real time. If the rotation speed is greater than zero and the current is within the operating threshold range, it is determined that the air preheater is in the operating state, and the operating flushing mode is triggered; if the rotation speed is zero and the current is lower than the shutdown threshold, it is determined to be in the shutdown state, and the shutdown flushing mode is triggered.

[0015] S2: In the operating flushing mode, control the straight guide rail to drive the flushing pipe to reciprocate radially, and at the same time, the high-pressure cluster nozzle sprays water flow at a preset pressure for dynamic flushing, and the ash discharge valve at the ash outlet is opened.

[0016] S3: In the shutdown flushing mode, start the blockage monitoring system, generate a blockage degree heat map of the heat transfer element through an infrared thermal imager and a differential pressure sensor array, and mark the target coordinates of the unflushed area.

[0017] S4: According to the target coordinates, control the stepping motor of the annular drive mechanism to drive the flushing pipe to rotate along the annular track to the target angle, and then radially move the flushing pipe to the specified radius position through the straight guide rail, and perform hierarchical flushing in the polar coordinate positioning mode.

[0018] The present invention has the following beneficial effects:

[0019] By integrating the operating flushing mode and the shutdown flushing mode, the present invention uses the state detection module to monitor the rotation speed and current of the heat transfer element mandrel in real time, and then drives the intelligent switching of the flushing mode, realizing the coordination of dynamic flushing during operation to maintain the basic cleanliness and precise positioning and deep flushing after shutdown, achieving the effect of reducing the shutdown time and improving the annual availability rate.

[0020] The present invention uses the linkage design of the annular track and the straight guide rail, combined with the polar coordinate system positioning algorithm, to drive the flushing pipe to achieve the combined movement of radial expansion and contraction and circumferential rotation, thereby achieving the coverage and flushing of the heat transfer element surface without dead angles;

[0021] The present invention integrates the data of infrared thermal imager and differential pressure sensor through the blockage monitoring system to generate a three-dimensional blockage thermal map, which in turn drives the dynamic adjustment of graded flushing pressure, realizes automatic matching of different gradient water pressures according to the degree of dust accumulation, achieves the purpose of water saving, and avoids the effect of overwashing in low blockage areas and damaging components. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 It is a bottom view of the air preheater of the present invention;

[0024] Figure 3 It is a schematic diagram of the linear drive mechanism of the present invention;

[0025] Figure 4 Schematic diagram of the annular drive mechanism of the present invention.

[0026] The reference numerals in the figure are as follows:

[0027] 1. Housing; 2. Heat transfer element; 3. Ash outlet; 4. Annular track; 5. Straight guide rail; 6. Flushing pipe; 7. Infrared thermal imager; 8. Pressure difference sensor; 41. Track connection base plate; 42. Annular gear ring; 43. Planetary gear; 51. Servo motor; 52. Driving gear; 53. Rack; 54. Guide base; 61. High-pressure cluster nozzle. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] See also Figures 1 to 4 , the invention provides a technical solution:

[0030] A dual-mode air preheater flushing system includes an air preheater, which consists of a housing 1 and heat transfer elements 2. The heat transfer elements 2 are rotatably arranged within the housing 1. It also includes a state detection module, a flushing structure, and an ash outlet 3. The flushing structure includes an annular track 4, a straight guide rail 5, and a flushing pipe 6 with high-pressure cluster nozzles 61. In the vertical direction, the position of the flushing pipe 6 is lower than the bottom surface of the heat transfer elements 2, enabling the high-pressure cluster nozzles 61 to be located below the heat transfer elements 2. The annular track 4 is arranged around the bottom surface of the heat transfer elements 2. The flushing pipe 6 realizes radial movement through a linear driving mechanism provided on the straight guide rail 5, and the bottom of the straight guide rail 5 is slidably connected to the annular track 4. The dual-mode air preheater flushing system integrates an operating flushing mode and a shutdown flushing mode. The operating flushing mode includes using the flushing pipe 6 to reciprocate along the straight guide rail 5 for radial flushing. The shutdown flushing mode includes an annular driving mechanism configured for the annular track 4. The flushing pipe 6 can be circumferentially rotated and positioned along the annular track 4 and perform staged flushing. The state detection module switches the flushing mode by monitoring the spindle state of the heat transfer elements 2. The ash outlet 3 is arranged at the bottom of the housing 1 and is equipped with an openable and closable ash discharge valve. The dual-mode design takes into account dynamic ash cleaning during operation and deep flushing after shutdown, reducing downtime. The annular track and the straight guide rail are linked to achieve full-area coverage. At the same time, it can avoid incomplete flushing that may be caused by dynamic ash cleaning during operation.

[0031] Meanwhile, to avoid flushing blind spots caused by the asynchronous rotation of the heat transfer elements and the movement of the flushing pipe, the rotation speed and the flushing speed can also be dynamically matched through a control module to ensure an increase in the coverage rate.

[0032] The state detection module includes a rotation speed sensor, a current detection unit, and a control module. The rotation speed sensor and the current detection unit judge whether the air preheater is in an operating or shutdown state by monitoring the rotation speed and working current of the spindle of the heat transfer elements 2. The control module triggers the corresponding flushing mode. By real-time monitoring of the rotation speed and current, the operating / shutdown state is automatically determined and the flushing mode is switched.

[0033] The above-mentioned air preheater generally refers to a rotary air preheater. The heat transfer elements 2 are cylindrical and rotate around the core axis. The spindle of the heat transfer elements 2 is a conventional setting method in the art, which is used to fix the heat transfer elements 2 and enable them to rotate at the same time. Of course, the rotation can be around the spindle or driven by the spindle.

[0034] The linear drive mechanism includes a servo motor 51 and a gear-rack transmission component. The gear-rack transmission component includes a servo motor 51, a driving gear 52, a rack 53, and a guiding base 54. The rack 53 is fixed to the upper surface of the straight guide rail 5 by bolts. The guiding base 54 is slidably connected to the straight guide rail 5 through a slider. The top of the guiding base 54 is rigidly connected to the flushing pipe 6 through a flushing pipe mounting bracket. The servo motor 51 is vertically installed on the side of the guiding base 54, and the output shaft of the servo motor 51 penetrates through the guiding base 54 and is connected to the driving gear 52 through a coupling. First, the driving gear 52 is driven to rotate by the servo motor 51, and then the driving gear 52 meshes with the rack 53 fixed on the straight guide rail 5 to convert the rotational motion into a linear motion. The guiding base 54 slides along the straight guide rail 5 to drive the flushing pipe 6 to move radially. The moving speed is controlled by the rotational speed of the servo motor 51. After reaching the end of the straight guide rail 5, the servo motor 51 reverses to drive the flushing pipe 6 to move in the reverse direction, forming a reciprocating flushing path. At the same time, photoelectric sensors can be installed at both ends of the straight guide rail 5. After being triggered, the servo motor 51 stops immediately to prevent mechanical overshoot.

[0035] The circular drive mechanism includes a stepping motor, a circular gear ring 42, and an orbital connection substrate 41. The circular gear ring 42 is fixedly installed on the inner side of the circular track 4, and the teeth of the circular gear ring 42 face inward. The orbital connection substrate 41 has an L-shaped structure. The vertical side of the orbital connection substrate 41 is fixedly and rigidly connected to the bottom of the straight guide rail 5 by bolts. The horizontal side of the orbital connection substrate 41 extends below the circular gear ring 42. The stepping motor is installed upside down on the lower surface of the horizontal side of the orbital connection substrate 41. The output shaft of the stepping motor penetrates upward through the orbital connection substrate 41 and is connected with a planetary gear 43. The planetary gear 43 meshes with the circular gear ring 42. The straight guide rail 5 is slidably connected to the circular track 4 through the orbital connection substrate 41. First, the planetary gear 43 is driven to rotate by the stepping motor, and then the planetary gear 43 meshes with the circular gear ring 42 to drive the orbital connection substrate 41 to move circumferentially along the circular track 4. Among them, the upside-down stepping motor is designed to be dustproof and waterproof and is suitable for high-temperature and high-humidity environments.

[0036] The shutdown flushing mode includes a blockage monitoring system, which includes an axial monitoring unit and a radial detection unit. The axial monitoring unit includes infrared thermal imagers 7 evenly distributed at equal intervals along the axis of the air preheater. The radial detection unit includes differential pressure sensors 8 arranged in a circumferential array on the air preheater. The infrared thermal imagers 7 are used to detect abnormal surface temperature areas caused by uneven heat dissipation due to ash accumulation. The differential pressure sensors 8 are used to measure the pressure difference between the inlet and outlet when air flows through the heat transfer element 2 to provide dynamic air flow resistance data. After the data provided by the axial monitoring unit and the radial detection unit are fused, a blockage degree thermal map is generated and the coordinates of the unflushed area are marked. After the shutdown flushing mode is started, the blockage monitoring system locates the unflushed area and synchronously sends it to the linear drive mechanism and the ring drive mechanism, and controls the flushing pipe 6 to move to the target position for staged flushing.

[0037] Specifically, first, due to ash accumulation in the blocked area, the heat dissipation is uneven and the temperature distribution is abnormal. Therefore, the surface of the heat transfer element 2 can be scanned by the infrared thermal imager 7, and then the differential pressure sensor 8 measures the air flow resistance. That is, because the blocked area will cause the air flow channel to become narrower or blocked, thereby increasing the pressure difference. The differential pressure sensor measures the pressure difference between the inlet and outlet when air flows through the heat transfer element 2 to generate real-time blockage data. The control module fuses the temperature and pressure difference data, draws a blockage degree thermal map through a weighted algorithm and marks the coordinates of the unflushed area, converts the coordinates of the blocked area into a polar coordinate system, and sends them to the ring drive mechanism and the linear drive mechanism. The drawing of the thermal map is the content of the prior art and will not be elaborated here.

[0038] The straight guide rail 5 and the ring track 4 form a linkage mechanism through the track connection substrate 41. In the shutdown mode, the flushing pipe 6 first rotates along the ring track 4 to the target angle, and then moves radially along the straight guide rail 5 to the specified radius to achieve precise positioning flushing in the polar coordinate system. The high-pressure cluster nozzle 61 is required to continuously flush the target area until the blockage mark in this area on the thermal map disappears before moving to the next area.

[0039] The dual-mode air preheater flushing system of this embodiment further includes a pressure regulation module for realizing staged flushing. The pressure regulation module is connected in series on the water supply pipeline between the flushing pipe 6 and an external high-pressure water source. The pressure regulation module includes a pressure sensor, an electric control valve, and a controller. The pressure sensor is used to monitor the water pressure at the nozzle in real time and feedback the data to the controller. The controller dynamically adjusts the opening degree of the electric control valve according to the blockage degree thermal map provided by the blockage monitoring system. Specifically, the pressure of the high-pressure cluster nozzle 61 is divided into three gears: the pressure is 2-4 MPa for the area where the blockage degree ≤ 30%, the pressure is 5-7 MPa for the area where 30% ≤ blockage degree ≤ 70%, and the pressure is 8-10 MPa for the area where the blockage degree ≥ 70%. First, the controller reads the blockage degree thermal map, and then sets the target water pressure according to the blockage level. After each flushing, the high-pressure cluster nozzle 61 can also be back blown with compressed air for a period of time to prevent impurities from blocking.

[0040] An air preheater flushing method includes the above-mentioned dual-mode air preheater flushing system, and is characterized by including the following steps:

[0041] S1: The state detection module is used to monitor the rotation speed and working current of the core shaft of the heat transfer element 2 in real time. If the rotation speed is greater than zero and the current is within the operating threshold range, it is determined that the air preheater is in the operating state, and the operating flushing mode is triggered. If the rotation speed is zero and the current is lower than the shutdown threshold, it is determined to be in the shutdown state, and the shutdown flushing mode is triggered.

[0042] S2: In the operating flushing mode, the straight guide rail 5 is controlled to drive the flushing pipe 6 to reciprocate radially, and at the same time, the high-pressure cluster nozzle 61 sprays water flow at a preset pressure for dynamic flushing, and the ash discharge valve of the ash outlet 3 is opened.

[0043] S3: In the shutdown flushing mode, the blockage monitoring system is started, and the blockage degree thermal map of the heat transfer element 2 is generated by the infrared thermal imager 7 and the differential pressure sensor array 8, and the target coordinates of the unflushed area are marked.

[0044] S4: According to the target coordinates, the stepping motor of the ring drive mechanism is controlled to drive the flushing pipe 6 to rotate along the ring track 4 to the target angle, and then the flushing pipe 6 is radially moved to the specified radius position through the straight guide rail 5 to perform staged flushing in the polar coordinate positioning mode.

[0045] Again, as a preference, a Helmholtz resonance cavity array can be integrated inside the high-pressure cluster nozzle 61. When the water flow passes through at high speed, it excites a directional sound beam. Its functions are as follows: First, it can form micron-sized bubbles in the water flow, and when the bubbles burst, shock waves are released to break up the caked ash layer. Second, the specific frequency sound wave resonates with the natural frequency of the ash particles to reduce their adhesion strength. At the same time, it can also play a role in saving water.

[0046] Piezoelectric ceramic vibrating pieces can also be embedded in the transmission mechanisms of the straight guide rail 5 and the annular track 4. When the flushing pipe 6 moves, low-frequency mechanical vibrations are applied, and the dust on the surface of the guide rail is shaken off to prevent jamming.

[0047] The above are only embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A dual-mode air preheater flushing system, comprising an air preheater, the air preheater comprising a housing (1) and a heat transfer element (2), the heat transfer element (2) being rotatably disposed in the housing (1), characterized in that: The system also includes a state detection module, a flushing structure and an ash outlet (3); the flushing structure includes an annular track (4), a straight guide rail (5) and a flushing pipe (6) with a high-pressure cluster nozzle (61); the annular track (4) is arranged around the bottom surface of the heat transfer element (2); the flushing pipe (6) is radially moved by a linear drive mechanism provided on the straight guide rail (5); the bottom of the straight guide rail (5) is slidably connected to the annular track (4); the dual-mode air preheater flushing system integrates an operating flushing mode and a shutdown flushing mode; the operating flushing mode includes using the flushing pipe (6) to reciprocate along the straight guide rail (5) to perform radial flushing; the shutdown flushing mode includes an annular drive mechanism provided on the annular track (4); the flushing pipe (6) can be rotated and positioned along the annular track (4) to perform graded flushing; the state detection module switches the flushing mode by monitoring the state of the core shaft of the heat transfer element (2); the ash outlet (3) is arranged at the bottom of the housing (1) and is provided with an ash discharge valve that can be opened and closed.

2. A dual-mode air preheater flushing system as claimed in claim 1, characterized in that: The state detection module comprises a rotation speed sensor, a current detection unit and a control module. The rotation speed sensor and the current detection unit monitor the rotation speed and working current of the core shaft of the heat transfer element (2) to determine whether the air preheater is in operation or shutdown state. The control module triggers a corresponding flushing mode.

3. A dual-mode air preheater flushing system as claimed in claim 1, characterized in that: The linear drive mechanism comprises a servo motor (51) and a gear rack transmission assembly, wherein the gear rack transmission assembly comprises a servo motor (51), a driving gear (52), a gear rack (53) and a guide base (54), wherein the gear rack (53) is fixed to the upper surface of the straight guide rail (5) by bolts, the guide base (54) is slidably connected to the straight guide rail (5) by a slider, and the top of the guide base (54) is rigidly connected to the flushing pipe (6) by a flushing pipe mounting frame; the servo motor (51) is vertically mounted on the side of the guide base (54), and the output shaft of the servo motor (51) passes through the guide base (54) and is connected to the driving gear (52) by a coupling.

4. A dual-mode air preheater flushing system as claimed in claim 1, characterized in that: The annular drive mechanism comprises a stepper motor, an annular gear ring (42) and a track connection base plate (41); the annular gear ring (42) is fixedly mounted on the inner side of the annular track (4), and the tooth surface of the annular gear ring (42) faces inward; the track connection base plate (41) is in an L-shaped structure; the vertical edge of the track connection base plate (41) is rigidly connected to the bottom of the linear guide rail (5) by bolts; the horizontal edge of the track connection base plate (41) extends below the annular gear ring (42); the stepper motor is invertedly mounted on the lower surface of the horizontal edge of the track connection base plate (41); the output shaft of the stepper motor passes through the track connection base plate (41) upward and is connected to a planetary gear (43); the planetary gear (43) is meshed with the annular gear ring (42); the linear guide rail (5) is slidably connected to the annular track (4) through the track connection base plate (41).

5. A dual-mode air preheater flushing system as claimed in claim 2, characterized in that: The shutdown flushing mode includes a blockage monitoring system, which includes an axial monitoring unit and a radial detection unit. The axial monitoring unit includes infrared thermal imagers (7) equidistantly distributed along the axial direction of the air preheater, and the radial detection unit includes differential pressure sensors (8) arranged in a circumferential array on the air preheater. The infrared thermal imager (7) is used to detect abnormal surface temperature areas due to uneven heat dissipation caused by dust accumulation, and the differential pressure sensor (8) is used to measure the inlet and outlet pressure differences when air flows through the heat transfer element (2) to provide dynamic airflow resistance data. The data provided by the axial monitoring unit and the radial detection unit are fused to generate a blockage degree thermal map and mark the coordinates of the unflushed areas. After the shutdown flushing mode is started, the blockage monitoring system locates the unflushed areas and sends them to the linear drive mechanism and the annular drive mechanism synchronously, and controls the flushing pipe (6) to move to the target position for graded flushing.

6. A dual-mode air preheater flushing system as claimed in claim 5, characterized in that: The straight guide rail (5) and the circular track (4) form a linkage mechanism via a track connection base plate (41); in the shutdown mode, the flushing pipe (6) first rotates along the circular track (4) to a target angle, and then moves radially along the straight guide rail (5) to a specified radius, thereby achieving precise positioning flushing in a polar coordinate system.

7. A dual-mode air preheater flushing system as claimed in claim 6, characterized in that: It also includes a pressure regulating module for achieving graded flushing, the pressure regulating module is connected in series on the water supply pipeline between the flushing pipe (6) and the external high-pressure water source, and the pressure regulating module includes a pressure sensor, an electric regulating valve and a controller; the pressure sensor is used to monitor the water pressure at the nozzle in real time and feed the data back to the controller, and the controller dynamically adjusts the opening of the electric regulating valve according to the blockage degree thermal map provided by the blockage monitoring system.

8. A dual-mode air preheater flushing system as claimed in claim 7, characterized in that: The pressure of the high-pressure clustering nozzle (61) is divided into three levels: a pressure of 2-4 MPa, which is used in areas with a blockage degree of ≤30%, a pressure of 5-7 MPa, which is used in areas with a blockage degree of 30%≤≤70%, and a pressure of 8-10 MPa, which is used in areas with a blockage degree of ≥70%.

9. An air preheater flushing method, comprising a dual-mode air preheater flushing system as claimed in any one of claims 5 to 8, characterized in that: The following steps are involved: S1: The rotation speed and working current of the core shaft of the heat transfer element (2) are monitored in real time through the state detection module. If the rotation speed is greater than zero and the current is within the operation threshold range, it is determined that the air preheater is in the operation state and the operation flushing mode is triggered; if the rotation speed is zero and the current is lower than the shutdown threshold, it is determined to be in the shutdown state and the shutdown flushing mode is triggered; S2: In the operation flushing mode, the straight guide rail (5) is controlled to drive the flushing pipe (6) to move back and forth in the radial direction, and at the same time, the high-pressure cluster nozzle (61) sprays water at a preset pressure to perform dynamic flushing, and the ash discharge valve of the ash outlet (3) is opened; S3: In the shutdown flushing mode, the blockage monitoring system is started, and a blockage degree thermal map of the heat transfer element (2) is generated through an infrared thermal imager (7) and a pressure difference sensor array (8), and the target coordinates of the unflushed area are marked; S4: According to the target coordinates, the stepper motor of the annular drive mechanism is controlled to drive the flushing pipe (6) to rotate along the annular track (4) to the target angle, and then the flushing pipe (6) is radially moved to a specified radius position through the straight guide rail (5), and graded flushing is performed in a polar coordinate system positioning manner.

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