A boiler heating surface ash removal system and method

Abstract

The application provides a boiler heating surface ash removal system and method, which comprises: a heating surface unit comprising a plurality of first pipes and a plurality of second pipes, the first pipes and the second pipes being arranged alternately and spaced apart in parallel; an ash deposition monitoring unit configured to monitor the ash deposition amount of the heating surface unit; and a desuperheating water unit configured to cool the first pipes when the ash deposition amount reaches a preset threshold, so that a difference in expansion amount is generated between the first pipes and the second pipes, and the relative displacement generated by the difference in expansion amount is used to remove the slag deposition on the heating surface unit. The system can realize a physical ash removal method based on temperature difference deformation, can efficiently strip stubborn slag deposition, completely avoids mechanical wear and tear and thermal stress damage to the pipe wall caused by high-pressure jet flow, significantly improves the operation safety and service life of the heating surface, and reduces the energy and working medium consumption caused by frequent ash blowing.

Description

Technical Field

[0001] This application relates to the field of boiler equipment ash removal technology, and more specifically, to a boiler heating surface ash removal system and method. Background Technology

[0002] In thermal power generating units burning low-ash-melting-point coal, severe slagging and ash accumulation are common problems on high-temperature heating surfaces such as the boiler furnace, superheater, and horizontal flue. This is mainly due to the melting and adhesion of alkali metals and alkaline earth metal compounds rich in coal ash at high temperatures. Severe ash accumulation not only significantly reduces the boiler's heat exchange efficiency and increases energy consumption, but also causes overheating of the heating surface metal due to localized heat transfer deterioration, threatening equipment safety. When large slag masses formed by ash deposits break off, they may impact and damage the furnace bottom equipment, or even trigger unplanned shutdowns.

[0003] Currently, the conventional technical means in the industry to solve the problem of ash removal on high-temperature heated surfaces is to install steam or sonic soot blowers and enhance the cleaning effect by increasing the blowing frequency and pressure. However, this method has inherent technical drawbacks: First, the jet of the blowing medium (steam or compressed air) has blind spots, and its cleaning effect on the back of closely arranged pipes and local areas of complex structures is limited, making it difficult to achieve thorough cleaning; second, high-frequency, high-pressure blowing will cause continuous mechanical wear and thermal shock to the heated pipe walls, leading to local thinning of the pipe walls, creating safety hazards, and shortening the service life of boiler pipes; finally, frequent blowing itself also consumes a large amount of working fluid and energy, reducing the economic efficiency of unit operation.

[0004] Therefore, there is an urgent need to develop a new type of ash removal technology that can fundamentally change the ash removal mechanism, effectively and thoroughly remove accumulated ash, and avoid damage to the heated surface itself. Summary of the Invention

[0005] This application provides at least one boiler heating surface ash removal system and method. The system can realize physical ash removal based on temperature difference deformation. It can not only efficiently remove stubborn slag and ash, but also completely avoid mechanical wear and thermal stress damage to the tube wall caused by high-pressure jet. While achieving efficient and thorough ash removal, it significantly improves the operational safety and service life of the heating surface, and reduces the energy and working fluid consumption caused by frequent soot blowing.

[0006] In a first aspect, embodiments of this application provide a boiler heating surface ash removal system, comprising: The heated surface unit includes multiple first pipes and multiple second pipes, wherein the first pipes and the second pipes are parallel to each other and arranged alternately at intervals. A dust accumulation monitoring unit is configured to monitor the amount of dust accumulation on the heated surface unit. A desuperheating water unit is configured to cool the first pipe when the amount of ash accumulation reaches a preset threshold, so as to create an expansion difference between the first pipe and the second pipe, and to use the relative displacement generated by the expansion difference to remove the slag and ash accumulation of the heated surface unit.

[0007] In one optional embodiment, the inlet of the first pipe is connected to the outlet of the desuperheating water unit, and the desuperheating water unit can add a low-temperature medium to the heat exchange medium of the first pipe to cool down the first pipe.

[0008] In one optional implementation, the first pipe and the second pipe circulate the heat exchange medium independently.

[0009] In one alternative implementation, both the first pipe and the second pipe are configured as U-shaped.

[0010] In one optional embodiment, the coefficient of linear expansion of the first pipe is greater than that of the second pipe.

[0011] In one optional implementation, the ash accumulation monitoring unit includes at least one of a high-temperature heat flow meter and an infrared thermometer.

[0012] In one optional embodiment, the ash accumulation monitoring unit is further configured to control the desuperheating water unit to cool the first pipe when the ash accumulation on the heated surface unit reaches a preset threshold.

[0013] In one optional implementation, a temperature monitoring unit is further included, which is configured to monitor the temperature of the first pipe.

[0014] In one optional embodiment, the temperature monitoring unit is further configured to control the decooling water unit to stop cooling the first pipe after the temperature of the first pipe decreases by a set value and remains at that value for a preset time.

[0015] Secondly, this application also provides a method for removing ash from the boiler heating surface, applicable to the boiler heating surface ash removal system described in any of the foregoing embodiments, comprising the following steps: Step S1: Monitor the ash accumulation status of the heated surface unit using the ash accumulation monitoring unit; Step S2: When the amount of ash accumulation is detected to reach the preset threshold, the desuperheating water unit is activated to cool the first pipe. Step S3: After the temperature of the first pipe drops to the set value and remains at the preset time, shut down the desuperheating water unit to restore the system to normal operation.

[0016] The above-mentioned technical solution of this application has the following beneficial technical effects: The boiler heating surface ash removal system of this application embodiment innovatively utilizes the differential expansion characteristics of the two types of pipes at operating temperatures to remove ash from the boiler heating surface. Specifically, when the ash accumulation reaches a preset threshold, the system precisely and actively cools the first pipe, creating a significant difference in expansion between it and the second pipe, which remains under high-temperature conditions. This induces controllable relative displacement and shearing action between the adjacent pipes. This physical ash removal method based on temperature difference deformation fundamentally changes the traditional passive soot blowing mode. It not only efficiently removes stubborn slag and ash (especially in soot blowing blind areas such as the back side of the pipe), but also completely avoids mechanical wear and thermal stress damage to the pipe wall caused by high-pressure jets. While achieving efficient and thorough ash removal, it significantly improves the operational safety and service life of the heating surface and reduces energy consumption caused by frequent soot blowing.

[0017] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. These drawings are incorporated in and constitute a part of this specification. They illustrate embodiments conforming to this application and, together with the specification, serve to explain the technical solutions of this application. It should be understood that the following drawings only show some embodiments of this application and should not be considered as limiting the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This illustration shows a schematic diagram of a boiler heating surface ash removal system provided in an embodiment of this application; Figure 2 This illustration shows a schematic diagram of the normal operation of the heated surface unit provided in an embodiment of this application; Figure 3 This illustration shows a schematic diagram of ash removal from a heated surface unit provided in an embodiment of this application. In the diagram: 1. First pipeline; 2. Second pipeline; 3. First inlet header; 4. First outlet header; 5. Second inlet header; 6. Second outlet header; 7. High-temperature heat flow meter; 8. Infrared thermometer; 9. Desuperheating water unit. Detailed Implementation

[0020] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0021] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0022] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0023] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] refer to Figure 1This application provides a boiler heating surface ash removal system, including a heating surface unit, an ash accumulation monitoring unit, and a desuperheating water unit 9. The heating surface unit includes multiple first pipes 1 and multiple second pipes 2, which are parallel to each other and alternately arranged. The ash accumulation monitoring unit is configured to monitor the amount of ash accumulation in the heating surface unit. The desuperheating water unit 9 is configured to cool the first pipes 1 when the ash accumulation reaches a preset threshold, so as to create an expansion difference between the first pipes 1 and the second pipes 2, and use the relative displacement generated by the expansion difference to remove the slag and ash accumulation in the heating surface unit. During use, the ash accumulation monitoring unit continuously monitors the ash accumulation status of the boiler heating surface unit online. When the ash accumulation is detected to reach a preset safety or efficiency threshold, the system automatically starts the desuperheating water unit 9 to actively and rapidly cool the first pipes 1. At the same time, the adjacent second pipes 2 maintain their original high-temperature operating state. Due to the rapid formation of a significant temperature difference between the two, the two types of pipes undergo differentiated thermal expansion / contraction, such as... Figure 2 and Figure 3 As shown, this generates controllable relative displacement and compression between closely adjacent pipes. This shearing and displacement action based on temperature difference deformation can efficiently peel off and remove slag and ash adhering to the pipe surface. The entire process does not require the intervention of high-pressure jets, and the system automatically returns to normal operation after the cleaning is completed.

[0026] Optionally, the desuperheating water unit 9 includes a water source storage tank, a high-pressure pump, a regulating valve, and a spraying device. During the dust removal process, the system controls the high-pressure pump and the regulating valve to open, and the low-temperature demineralized water is atomized by the spraying device and injected at high speed into the inlet of the first pipe 1, thereby achieving active and rapid cooling of the first pipe 1. It should be understood that in practical applications, in addition to controlling the start and stop of the desuperheating water unit 9, the system can also control the flow rate of the desuperheating water (i.e., control the opening of the regulating valve) to achieve temperature control.

[0027] Optionally, the inlet of the first pipe 1 is connected to the outlet of the desuperheating water unit 9. The desuperheating water unit 9 can add a low-temperature medium to the heat exchange medium of the first pipe 1 to cool it down. By directly connecting the inlet of the first pipe 1 to the outlet of the desuperheating water unit 9, an efficient, direct, and easily controllable cooling execution path is constructed. This design allows the desuperheating water unit 9 to accurately mix the low-temperature medium (such as desuperheating water) directly into the mainstream heat exchange medium of the first pipe 1, thereby achieving rapid and proactive intervention on the target pipe temperature. This direct cooling method has a rapid response and low thermal inertia, ensuring that the temperature of the first pipe 1 can be significantly reduced in a short time after the ash accumulation monitoring unit is triggered, thereby quickly forming a preset temperature difference with the adjacent second pipe 2, efficiently inducing the required expansion difference and relative displacement. This not only enhances the timeliness and reliability of the ash removal action but also avoids energy loss and control delay caused by complex intermediate heat exchange links or external cooling.

[0028] Optionally, the first pipe 1 and the second pipe 2 circulate heat exchange media independently. By setting the first pipe 1 and the second pipe 2 as a system with independently circulating heat exchange media, completely independent temperature control conditions are created for the two types of pipes. This design allows the system to cool the first pipe 1 independently and precisely without interfering with the normal high-temperature operation of the second pipe 2. The independent circulation path fundamentally avoids the diffusion or crosstalk of the cooling medium and heat to the adjacent second pipe 2, ensuring that during the cleaning process, the first pipe 1 can be effectively cooled to the target temperature, while the second pipe 2 can stably maintain its original high-temperature state. This precise "cold and hot isolation" can significantly increase the controllable temperature difference between the two types of pipes, thereby ensuring or enhancing the expansion difference and shear force effect required for cleaning. In this embodiment, the inlet and outlet of the first pipe 1 are connected to the first inlet header 3 and the first outlet header 4, respectively. The heat exchange medium in the first inlet header 3 flows through the first pipe 1 into the first outlet header 4. The inlet and outlet of the second pipe 2 are connected to the second inlet header 5 and the second outlet header 6, respectively. The heat exchange medium in the second inlet header 5 flows through the second pipe 2 into the second outlet header 6. Of course, in a specific configuration, the first pipe 1 can be connected to the outlet of the desuperheating water unit 9 through the first inlet header 3. In use, the desuperheating water unit 9 can first spray the low-temperature medium into the first inlet header 3, and then the first inlet header 3 sends the mixture of the heat exchange medium and the low-temperature medium (with a temperature lower than that of the heat exchange medium) into the first pipe 1.

[0029] Optionally, both the first pipe 1 and the second pipe 2 are U-shaped. By framing both the first pipe 1 and the second pipe 2 as U-shaped structures, the overall structural flexibility and deformation coordination of the heating surface unit during the cleaning process are greatly enhanced. Specifically, the unique geometric feature of the U-shaped pipe—fixed at both ends and freely expandable in the middle—allows the shrinkage deformation generated when the system cools the first pipe 1 to be smoothly transmitted and released along the U-shaped bend, resulting in a significant lateral relative displacement between the middle of the pipe and the adjacent, high-temperature second pipe 2. This "U-shaped lever" effect not only amplifies the deformation amplitude caused by the temperature difference, making the shearing and squeezing action required for cleaning more powerful and uniform, but also the U-shaped structure itself has good elasticity, effectively absorbing and buffering thermal stress, avoiding excessive concentrated stress at the fixed end of the pipe due to temperature difference deformation. Thus, while achieving efficient and thorough cleaning, it ensures the structural safety and long-term operational reliability of the entire heating surface unit.

[0030] Optionally, the coefficient of linear expansion of the first pipe 1 is greater than that of the second pipe 2. By limiting the coefficient of linear expansion of the first pipe 1 to be greater than that of the second pipe 2, it means that under the same temperature difference, the first pipe 1 will produce a more significant shrinkage than the second pipe 2. This difference in expansion, "amplified" by the difference in material properties, can be directly converted into a stronger relative displacement driving force and a more effective extrusion and shearing action between adjacent pipes. This design not only enables the desired dust removal effect to be achieved at a smaller operating temperature difference, thereby reducing the system's energy consumption requirements and the disturbance to the heat exchange process, but also allows for effective peeling of stubborn, highly adhesive ash through a sufficiently large deformation force guaranteed by the material properties, ensuring the reliability and thoroughness of the dust removal action. In this embodiment, the coefficient of linear expansion of the first pipe 1 is 0.0126 mm / ℃·m, and the pipe length is 12 m. When the temperature of the first pipe 1 decreases by A, its expansion decreases to 0.0126 × A × 12.

[0031] Optionally, the ash accumulation monitoring unit includes at least one of a high-temperature heat flow meter 7 and an infrared thermometer 8. The high-temperature heat flow meter 7 can be directly embedded or closely attached to the wall of the heated surface tube (or a specific monitoring point on the tube panel). Its installation location is selected in a key area prone to ash accumulation and representative of the overall heat exchange status of the heated surface, such as the center of the tube bank or a typical location on the windward / leeward side. Its working principle is based on the laws of thermal conduction, directly calculating the heat flux density transferred per unit area per unit time by measuring the small temperature difference across the sensing element (usually using the thermopile principle). When the heated surface is covered with ash, the ash layer forms additional thermal resistance on the outside of the tube wall, resulting in impeded heat transfer from the flame and flue gas to the tube wall metal, causing a significant decrease in the heat flux value measured by the heat flow meter. By monitoring and comparing the heat flux data of the clean state with the current state in real time, the system can accurately quantify the thickness and severity of ash accumulation. An infrared thermometer (or infrared thermal imager) is a non-contact measuring device. It can be installed in a dedicated observation window or sleeve on a boiler wall or steel frame. The lens, through a high-temperature resistant lens (such as a sapphire lens), is directly aimed at the heated surface area to be monitored (such as the tube bank of a screen-type superheater or high-temperature reheater). The installation position must ensure that its field of view clearly covers the target tube bank and avoid direct impact from flames and high-temperature flue gas on the lens. It also requires an air or water cooling jacket for cooling and purging to maintain lens cleanliness and the instrument's normal operating temperature. The infrared thermometer detects the infrared energy radiated outward from the surface of the heated tube wall and calculates the surface temperature of the tube wall according to the Stefan-Boltzmann law. When the heated surface is clean, the tube wall is directly exposed to the high-temperature flue gas, resulting in a high and relatively uniform surface temperature. Once ash accumulates on the tube wall surface, the ash layer acts as insulation, causing a significant decrease in the surface temperature of the covered area. Infrared scanning can visually generate a temperature distribution heat map. By analyzing the uniformity of the temperature field, the temperature drop in a specific area, or the absolute temperature value, the system can determine the location, extent, and severity of dust accumulation. In this embodiment, the dust accumulation monitoring unit is equipped with both a high-temperature heat flow meter 7 and an infrared thermometer 8, which mutually verify each other, improving the reliability of the equipment.

[0032] Optionally, the ash accumulation monitoring unit is also configured to control the desuperheating water unit 9 to cool the first pipe 1 when the ash accumulation on the heated surface unit reaches a preset threshold. In other words, the ash accumulation monitoring unit can embed control logic to achieve seamless linkage between monitoring, judgment, and control, forming an automated closed-loop ash removal system with the heated surface unit and the desuperheating water unit 9. Specifically, when the ash accumulation monitoring unit detects in real time that the ash accumulation on the heated surface unit has reached the preset threshold, it can immediately and automatically generate control commands to directly control the desuperheating water unit 9 to precisely cool the first pipe 1. This integrated design completely avoids the response delays, judgment errors, and operational risks caused by traditional manual intervention or manual operation of subsystems, ensuring that the ash removal action is triggered promptly and accurately at the optimal time. It not only significantly improves the timeliness and accuracy of ash removal operations, enabling the system to "sense and act," proactively intervening before the ash accumulation reaches the critical point affecting operational safety, preventing problems before they occur. Furthermore, this automated closed-loop control can significantly reduce the operational burden on operators and eliminate the possibility of operational errors or delays caused by human factors. In this embodiment, the ash accumulation monitoring unit includes a first controller. The first controller receives monitoring signals from the high-temperature heat flow meter 7 and the infrared thermometer 8 and processes and analyzes the monitoring signals to obtain the ash accumulation amount. When the ash accumulation amount exceeds a set threshold, the first controller sends a desuperheating water start control signal to the desuperheating water unit 9.

[0033] Optionally, a temperature monitoring unit is also included, configured to monitor the temperature of the first pipe 1. By adding a temperature monitoring unit, the system can continuously and directly measure the current temperature of the first pipe 1, enabling precise control over the effectiveness and dynamic changes of the cooling operation. Specifically, when the dust accumulation monitoring unit determines that dust removal is necessary and activates the desuperheating water unit 9 to cool the first pipe 1, the temperature monitoring unit simultaneously tracks its temperature drop curve. Once the system detects that the temperature of the first pipe 1 has dropped to a preset target value (e.g., below a certain temperature difference from the adjacent second pipe 2) and has remained stable at this temperature for a preset duration (to ensure sufficient expansion difference formation and completion of the dust removal action), the system can control the desuperheating water unit 9 to stop cooling. This closed-loop process ensures that the dust removal operation is accurate, controllable, and safe, preventing equipment risks caused by excessive cooling. In this embodiment, the temperature monitoring unit includes at least one temperature sensor, which is installed on the first pipe 1 to detect the temperature of the first pipe 1.

[0034] Optionally, the temperature monitoring unit is also configured to control the desuperheating water unit 9 to stop cooling the first pipe 1 after the temperature of the first pipe 1 drops to a set value and remains at that value for a preset time. By providing the temperature monitoring unit with an automatic termination mechanism, it can be ensured that each cleaning operation ends after sufficient and reproducible temperature difference deformation, guaranteeing the consistency of the cleaning effect. More importantly, the preset "heat preservation time" provides the necessary duration for the relative displacement between adjacent pipes and the removal of accumulated ash, allowing the deformation shear force to do sufficient work and avoiding incomplete cleaning due to insufficient cooling time. At the same time, this automatic termination mechanism can also effectively prevent the risk of "overcooling," that is, to prevent the first pipe 1 from undergoing excessive contraction due to unnecessary continuous cooling, causing unexpected mechanical stress or affecting downstream working fluid parameters, thereby improving the intelligence and reliability of the entire system operation. In this embodiment, the temperature monitoring unit includes a second controller. The second controller can receive the temperature signal sent by the temperature sensor and calculate the temperature drop value of the first pipe 1 based on the temperature value at different time points. When the temperature drop value of the first pipe 1 reaches the set value and is maintained for a preset time, the second controller can send a de-cooling water stop control signal to the de-cooling water unit 9.

[0035] This application also provides a method for using a boiler heating surface ash removal system, the method comprising the following steps: Step S1: Monitor the ash accumulation status of the heated surface unit using the ash accumulation monitoring unit; Step S2: When the amount of ash accumulation is detected to reach the preset threshold, the desuperheating water unit 9 is activated to cool down the first pipe 1; Step S3: When the temperature of the first pipe 1 drops to a set value (e.g., 50°C to 100°C) and is maintained for a preset time (e.g., 1 to 2 minutes), the desuperheating water unit 9 is turned off to restore the system to normal operation.

[0036] It should be noted that the above method is only a single ash removal operation. To ensure the removal effect, the system can perform multiple operations. Moreover, for stubborn ash, the system can gradually increase the temperature reduction during the operation. The temperature reduction range and ash removal frequency of the system for the first pipe 1 can be determined based on the ash removal effect feedback from the ash monitoring system.

[0037] The boiler heating surface ash removal system of this application embodiment innovatively utilizes the differential expansion characteristics of the two types of pipes at operating temperatures to remove ash from the boiler heating surface. Specifically, when the ash accumulation reaches a preset threshold, the system precisely and actively cools the first pipe, creating a significant difference in expansion between it and the second pipe, which remains under high-temperature conditions. This induces controllable relative displacement and shearing action between the adjacent pipes. This physical ash removal method based on temperature difference deformation fundamentally changes the traditional passive soot blowing mode. It not only efficiently removes stubborn slag and ash (especially in soot blowing blind areas such as the back side of the pipe), but also completely avoids mechanical wear and thermal stress damage to the pipe wall caused by high-pressure jets. While achieving efficient and thorough ash removal, it significantly improves the operational safety and service life of the heating surface and reduces energy consumption caused by frequent soot blowing.

[0038] One or more embodiments in this specification are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this specification should be included within the protection scope of this application.

[0039] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A boiler heating surface ash removal system, characterized in that, include: The heated surface unit includes multiple first pipes and multiple second pipes, wherein the first pipes and the second pipes are parallel to each other and arranged alternately at intervals; A dust accumulation monitoring unit is configured to monitor the amount of dust accumulation on the heated surface unit. A desuperheating water unit is configured to cool the first pipe when the amount of ash accumulation reaches a preset threshold, so as to create an expansion difference between the first pipe and the second pipe, and to use the relative displacement generated by the expansion difference to remove the slag and ash accumulation of the heated surface unit.

2. The boiler heating surface ash removal system according to claim 1, characterized in that, The inlet of the first pipe is connected to the outlet of the desuperheating water unit, which can add a low-temperature medium to the heat exchange medium of the first pipe to cool the first pipe.

3. The boiler heating surface ash removal system according to claim 1, characterized in that, The first pipeline and the second pipeline circulate heat exchange media independently.

4. The boiler heating surface ash removal system according to claim 1, characterized in that, Both the first pipe and the second pipe are U-shaped.

5. The boiler heating surface ash removal system according to claim 1, characterized in that, The coefficient of linear expansion of the first pipe is greater than that of the second pipe.

6. The boiler heating surface ash removal system according to claim 1, characterized in that, The ash accumulation monitoring unit includes at least one of a high-temperature heat flow meter and an infrared thermometer.

7. The boiler heating surface ash removal system according to claim 1, characterized in that, The ash accumulation monitoring unit is also configured to control the cooling water unit to cool the first pipe when the ash accumulation on the heated surface unit reaches a preset threshold.

8. The boiler heating surface ash removal system according to claim 1, characterized in that, It also includes a temperature monitoring unit, which is configured to monitor the temperature of the first pipe.

9. The boiler heating surface ash removal system according to claim 8, characterized in that, The temperature monitoring unit is also configured to control the de-cooling water unit to stop cooling the first pipe after the temperature of the first pipe drops by a set value and remains at that value for a preset time.

10. A method for removing ash from the heating surface of a boiler, applicable to the boiler heating surface ash removal system according to any one of claims 1-9, characterized in that, Includes the following steps: Step S1: Monitor the ash accumulation status of the heated surface unit using the ash accumulation monitoring unit; Step S2: When the amount of ash accumulation is detected to reach the preset threshold, the desuperheating water unit is activated to cool the first pipe. Step S3: After the temperature of the first pipe drops to the set value and remains at the preset time, shut down the desuperheating water unit to restore the system to normal operation.

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