Refined expansion monitoring system and method for boiler water walls

Abstract

The application discloses a kind of fine expansion monitoring system and method for boiler water cooling wall, system includes measuring table, laser emitting device, light target and control device, by grid region division to water cooling wall, can fine monitoring the expansion change amount and expansion area boundary of specific area tube panel, simultaneously, monitoring time can be arbitrarily selected, belongs to continuity monitoring, can accumulate a large amount of measurement data, can form the change trend of specific area tube panel expansion of furnace, further truly reflect the expansion change situation of boiler water cooling wall in the process of unit operation, especially when the load fluctuation of depth peak-shaving unit.By laser ranging, the measurement accuracy can be guaranteed. The measurement result is more accurate by the application, and the on-line, remote and real-time monitoring can be realized without the need for technical personnel to conduct on-site measurement, which is convenient and efficient without operation risk.

Description

Technical Field

[0001] This invention relates to the field of engineering monitoring, and in particular to a refined expansion monitoring system and method for boiler water-cooled walls. Background Technology

[0002] Water-cooled walls are the main heat-receiving part of a boiler, consisting of many parallel tubes distributed around the boiler furnace. The function of water-cooled walls is to absorb the radiant heat from the high-temperature flames or flue gas in the furnace and generate steam or hot water inside the tubes. Therefore, during boiler operation, the water-cooled wall tubes will expand due to heat. When the boiler load changes, the water-cooled wall tubes will undergo relative expansion or contraction. Excessive or frequent expansion of the tubes can easily cause the tubes to crack or become fatigued, which can easily lead to water-cooled wall leakage accidents. Therefore, strengthening the expansion monitoring of boiler water-cooled walls is one of the effective means to ensure the safe operation of the boiler.

[0003] Under the current context of deep peak shaving, the drastic changes in boiler load and the expansion and contraction of the furnace are more pronounced. Traditional boiler expansion monitoring methods are somewhat monotonous and outdated, and cannot accurately reflect the expansion changes of the boiler.

[0004] Currently, boiler furnace expansion monitoring commonly uses a mechanical coordinate indicator. This indicator consists of a steel pointer and an iron plate marked with a coordinate grid, welded to the monitoring location. The furnace expansion is represented by the change in the pointer's reading on the coordinate grid. Monitoring boiler furnace expansion using mechanical coordinate indicators often has the following problems: First, traditional coordinate indicators are single-point positioned, only vaguely reflecting the expansion changes in a fixed area of ​​the water-cooled wall tube panel, and the boundaries of the indicated area are unclear. Furthermore, they cannot accurately reflect the expansion changes in smaller, non-fixed areas. For example, in boilers participating in deep peak shaving, significant load changes are controlled by the boiler's coal and water feed. Changes in coal feed cause rapid changes in the magnitude and spatial distribution of the combustion calorific value inside the furnace. Simultaneously, changes in water feed together cause significant alterations in the heat transfer process between the two phases of the medium inside and outside the boiler's water-cooled wall tubes. Expansion and contraction occur in specific regions, and these regions are primarily related to the control methods of coal and water feed. Changes in the control methods of coal and water feed will also change the expansion and contraction area. Traditional coordinate indicators cannot achieve precise monitoring and boundary determination of this area. Secondly, the measurement data of coordinate indicators is relatively scattered, requiring technicians to record readings on-site for each measurement, which is a "discontinuous" measurement method and cannot reflect the short-term expansion and contraction trend of the furnace during deep peak shaving. In addition, traditional coordinate indicators rely on pointer readings, resulting in low measurement accuracy. Furthermore, the environment in which coordinate indicators are installed is often harsh, making them prone to damage. Some coordinate indicators are poorly positioned, and the measurement process also poses certain safety risks, making it inconvenient for technicians to conduct on-site measurements. Summary of the Invention

[0005] The purpose of this invention is to provide a refined expansion monitoring system and method for boiler water-cooled walls, which can realize online, remote, accurate, real-time and refined monitoring of the expansion of boiler water-cooled walls.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A refined expansion monitoring system for boiler water-cooled walls includes a measuring platform, a laser emitting device, a light target, and a control device, wherein the measuring platform and the light target are arranged on the boiler water-cooled wall tube panel.

[0008] The measuring platform is equipped with four laser emitting devices. The angle between the light emission directions of any two adjacent laser emitting devices is 90°. The measuring platform is also equipped with four beam holes, which correspond to the four laser emitting devices respectively, so that the light beam emitted by any laser emitting device passes through the corresponding beam hole and is incident on the corresponding light target, thereby realizing distance measurement.

[0009] The measuring platform is also equipped with a data transmission module, which is used to transmit the measured distance data to the control device, and the control device is used to store and calculate the data.

[0010] Optionally, a support column is provided at the bottom of the measuring platform, and the measuring platform is fixed to the boiler water-cooled wall tube panel by the support column.

[0011] Optionally, the optical target includes a target handle and a target plate, the target handle is connected to the target plate, and the optical target is fixed to the boiler water-cooled wall tube panel through the target handle.

[0012] Optionally, the measuring station has a distance measurement accuracy of 0.1 mm.

[0013] A method for refined expansion monitoring of boiler water-cooled walls, employing the refined expansion monitoring system for boiler water-cooled walls described in any one of the above claims, comprising:

[0014] Step S1: Select a monitoring area in the boiler water-cooled wall tube panel, and divide the monitoring area into multiple grid areas to be measured;

[0015] Step S2: Select any of the grid regions to be tested and denote it as ABCD. Divide the selected grid region to be tested into four equal parts to form four small rectangular grids, which are respectively denoteed as grid AEOH, grid EBFO, grid HOGD and grid OFCG.

[0016] Step S3: Arrange the measuring stage at point O, the intersection of the four small rectangular grids, and arrange the optical targets at points E, F, G and H respectively;

[0017] Step S4: At the first moment t0 of boiler operation, turn on the four laser emitting devices. The beam emitted by each laser emitting device passes through the corresponding beam aperture and is incident on the corresponding light target. The distance from the measuring platform to each light target is measured and recorded as d1, d2, d3 and d4 respectively.

[0018] Step S5: Repeat step S4 above at the second time t of boiler operation to measure the distances from the measuring platform to each of the optical targets at the second time t of boiler operation, and record them as d1', d2', d3' and d4' respectively;

[0019] Step S6: Calculate the change in distance from the measuring station to each of the optical targets in the grid area to be measured at the second time t, compared to the first time t0, and record them as △d1, △d2, △d3 and △d4 respectively.

[0020] Optionally, △d1, △d2, △d3 and △d4 represent the expansion displacement of the four selected small rectangular grid regions, where △d1 represents the vertical expansion displacement of the AEOH and EBFO grid regions, △d2 represents the horizontal expansion displacement of the EBFO and OFCG grid regions, △d3 represents the vertical expansion displacement of the OFCG and HOGD grid regions, and △d4 represents the horizontal expansion displacement of the HOGD and AEOH grid regions.

[0021] Optionally, during boiler operation, multiple moments are selected as the boiler changes from a first load to a second load. At each moment, step S4 is repeated to measure the distance from the measuring platform to each of the optical targets, thereby forming a trend of expansion of the boiler water-cooled wall tubes.

[0022] As can be seen from the above technical solution, the refined expansion monitoring system for boiler water-cooled walls provided by the present invention includes a measuring platform, laser emitting devices, a light target, and a control device. The measuring platform and the light target are arranged on the boiler water-cooled wall tube panel. The measuring platform is equipped with four laser emitting devices, wherein the angle between the emission directions of any two adjacent laser emitting devices is 90°. The measuring platform is also equipped with four beam apertures, each corresponding to one of the four laser emitting devices, so that the beam emitted by any laser emitting device passes through the corresponding beam aperture and is incident on the corresponding light target, thereby realizing distance measurement. The measuring platform is also equipped with a data transmission module, which is used to transmit the measured distance data to the control device, and the control device is used to store and calculate the data.

[0023] The present invention provides a refined expansion monitoring method for boiler water-cooled walls. A monitoring area is selected in the boiler water-cooled wall tube panel, and the monitoring area is divided into multiple grid areas to be measured. The grid areas to be measured are divided into four small rectangular grids. A measuring station and a light target are installed at corresponding points of the four small rectangular grids. The distance from the measuring station to each light target is measured at different times of boiler operation, and the change in distance is calculated.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] By dividing the water-cooled wall into gridded regions, the expansion changes and boundaries of specific areas of the tube wall can be monitored with precision. Furthermore, the monitoring time can be arbitrarily selected, enabling continuous monitoring and the accumulation of a large amount of measurement data. This allows for the formation of expansion trends in specific areas of the furnace tube wall, further reflecting the true expansion changes of the boiler water-cooled wall during unit operation, especially in deep peak-shaving units under load fluctuations. Laser ranging ensures measurement accuracy. This invention provides more accurate measurement results, eliminates the need for on-site technical personnel, and enables online, remote, and real-time monitoring—convenient, efficient, and risk-free. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a measuring platform for a refined expansion monitoring system for boiler water-cooled walls, provided in an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of the structure of a light target for a refined expansion monitoring system for boiler water-cooled walls, provided in an embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram illustrating the application of a refined expansion monitoring system for boiler water-cooled walls according to an embodiment of the present invention.

[0030] Figure 4 This is a schematic diagram of the gridded division of the water-cooled wall tube panel in one embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of selecting a large rectangular grid in the gridded area of ​​the water-cooled wall tube screen according to one embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram illustrating the division of a large rectangular grid into smaller rectangular grids in one embodiment of the present invention.

[0033] The reference numerals in the accompanying drawings include:

[0034] 100-Measuring stage, 101-First laser emitting device, 102-Second laser emitting device, 103-Third laser emitting device, 104-Fourth laser emitting device, 105-Beam aperture, 106-Support column, 107-First optical target, 108-Second optical target, 109-Third optical target, 110-Fourth optical target, 111-Target plate, 112-Target handle, 113-Control device, 7-Water-cooled wall panel. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0036] This embodiment provides a refined expansion monitoring system for boiler water-cooled walls, including a measuring platform 100, a laser emitting device, a light target, and a control device 113. The measuring platform 100 and the light target are arranged on the boiler water-cooled wall tube panel.

[0037] The measuring stage 100 is equipped with four laser emitting devices. The angle between the light emission directions of any two adjacent laser emitting devices is 90°. The measuring stage 100 is also equipped with four beam holes 105, which correspond to the four laser emitting devices respectively, so that the light beam emitted by any laser emitting device passes through the corresponding beam hole 105 and is incident on the corresponding light target, thereby realizing distance measurement.

[0038] The measuring platform 100 is also equipped with a data transmission module, which is used to transmit the measured distance data to the control device 113, and the control device 113 is used to store and calculate the data.

[0039] A measuring platform 100 is arranged on the boiler water-cooled wall tube panel, and four optical targets are also arranged on the boiler water-cooled wall tube panel, each corresponding to one of the four laser emitting devices on the measuring platform 100. For any laser emitting device, the laser beam emitted by the laser emitting device passes through the corresponding beam aperture 105 and is incident on the corresponding optical target, thereby measuring the distance to the corresponding optical target. Compared with the existing mechanical coordinate indicator, the refined expansion monitoring system for boiler water-cooled walls of this embodiment can achieve online, remote, accurate, real-time, and refined monitoring of the expansion of boiler water-cooled walls.

[0040] The laser emitting device can be equipped with a laser source to emit a laser beam. This system monitors the expansion of boiler water-cooled wall tubes based on optical distance measurement, improving the measurement accuracy compared to existing mechanical coordinate indicators. The measuring platform 100 has a measurement accuracy of 0.1mm, ensuring high precision.

[0041] For example, refer to Figure 1 , Figure 1 The figure shows a schematic diagram of a measuring platform for a refined expansion monitoring system for boiler water-cooled walls, as provided in one embodiment. The measuring platform 100 is equipped with a first laser emitting device 101, a second laser emitting device 102, a third laser emitting device 103, and a fourth laser emitting device 104, arranged adjacent to each other at 90° angles. Four beam apertures 105 are evenly distributed along the edge of the measuring platform 100, positioned vertically, horizontally, and vertically. After arranging the optical target, the target plate 111 of the optical target is aligned with the corresponding beam aperture 105 and the laser emitting device, allowing the laser beam emitted by the laser emitting device to pass through the corresponding beam aperture 105 and incident on the target plate 111 of the corresponding optical target.

[0042] In this embodiment, the structure of the optical target is not limited. In some embodiments, the optical target includes a target handle 112 and a target plate 111, with the target handle 112 connected to the target plate 111, as exemplarily described in reference to [reference needed]. Figure 2 , Figure 2 This is a schematic diagram of the structure of a light target for a fine expansion monitoring system for boiler water-cooled walls, provided in one embodiment. The light target can be fixed to the water-cooled wall tube panel 7 by the target handle 112, for example, fixed to the fins of the water-cooled wall tube panel 7, and the light beam emitted by the laser emitting device falls on the target plate 111.

[0043] The measuring platform 100 may also be equipped with a data measurement module. This module obtains the distance from the measuring platform 100 to the target based on the laser beam emitted by the laser emitter. The data transmission module transmits the measured distance data to the control device 113. Both the data measurement module and the data transmission module can be located inside the measuring platform 100. A support column 106 can be installed at the bottom of the measuring platform 100, and the measuring platform 100 is fixed to the boiler water-cooled wall panel 7 via the support column 106, for example, fixed to the fins of the boiler water-cooled wall panel 7. The control device 113 stores and calculates the data to achieve online monitoring of the expansion of a selected area of ​​the water-cooled wall panel 7. The control device 113 can be a computer, i.e., a computer terminal.

[0044] This embodiment also provides a refined expansion monitoring method for boiler water-cooled walls, which applies the refined expansion monitoring system for boiler water-cooled walls described in any of the above embodiments, and includes the following steps:

[0045] Step S1: Select a monitoring area in the boiler water-cooled wall tube panel 7, and divide the monitoring area into grids to form multiple grid areas to be measured;

[0046] Step S2: Select any of the grid regions to be tested and denote it as ABCD. Divide the selected grid region to be tested into four equal parts to form four small rectangular grids, which are respectively denoteed as grid AEOH, grid EBFO, grid HOGD and grid OFCG.

[0047] Step S3: Arrange the measuring stage 100 at point O, the intersection of the four small rectangular grids, and arrange the light target at points E, F, G and H respectively;

[0048] Step S4: At the first moment t0 of boiler operation, turn on the four laser emitting devices. The beam emitted by each laser emitting device passes through the corresponding beam hole 105 and is incident on the corresponding light target. The distances from the measuring stage 100 to each light target are measured and recorded as d1, d2, d3 and d4 respectively.

[0049] Step S5: Repeat step S4 above at the second time t of boiler operation to measure the distances from the measuring platform 100 to each of the optical targets at the second time t of boiler operation, and record them as d1', d2', d3' and d4' respectively;

[0050] Step S6: Calculate the change in distance from the measuring station 100 to each of the optical targets in the grid area to be measured at the second time t, compared to the first time t0, and record them as △d1, △d2, △d3 and △d4 respectively.

[0051] Examples can be combined with references Figure 3 , Figure 3 The figure shows an application demonstration of a refined expansion monitoring system for boiler water-cooled walls, as provided in one embodiment. The selected grid area ABCD to be measured is divided into four small rectangular grids, which are denoted as grid AEOH, grid EBFO, grid HOGD and grid OFCG, respectively. A measuring platform 100 is installed at point O, and a first optical target 107, a second optical target 108, a third optical target 109 and a fourth optical target 110 are installed at points E, F, G and H, respectively.

[0052] This embodiment of the refined expansion monitoring method for boiler water-cooled walls utilizes a gridded regional division to precisely monitor the expansion changes and boundaries of specific areas within the tube wall. Furthermore, the monitoring time is flexible and continuous, allowing for the accumulation of substantial measurement data. This data reveals the expansion trends in specific areas of the furnace tube wall, providing a more accurate reflection of the boiler water-cooled walls' expansion during unit operation, particularly in deep peak-shaving units under load fluctuations. Laser ranging ensures measurement accuracy. This refined expansion monitoring method for boiler water-cooled walls provides more precise measurement results, eliminates the need for on-site technical personnel, and enables online, remote, and real-time monitoring—offering convenience, efficiency, and no operational risks.

[0053] Wherein, △d1 = d1′-d1, △d2 = d2′-d2, △d3 = d3′-d3, and △d4 = d4′-d4. In some embodiments, △d1, △d2, △d3, and △d4 represent the expansion displacement of four selected small rectangular grid regions, respectively. △d1 represents the vertical expansion displacement of the AEOH and EBFO grid regions, △d2 represents the horizontal expansion displacement of the EBFO and OFCG grid regions, △d3 represents the vertical expansion displacement of the OFCG and HOGD grid regions, and △d4 represents the horizontal expansion displacement of the HOGD and AEOH grid regions. The horizontal direction of the water-cooled wall tube panel 7 can refer to the direction perpendicular to the water-cooled wall tubes, or it can refer to the direction parallel to the water-cooled wall tubes. For other grid areas to be monitored, namely large rectangular grid areas, which are divided into monitoring areas in the monitoring area of ​​boiler water-cooled wall tube panel 7, the installation and monitoring methods of grid ABCD can be used as a reference.

[0054] In some embodiments, during boiler operation, multiple moments can be selected as the boiler changes from a first load to a second load. At each moment, step S4 is repeated to measure the distance from the measuring platform 100 to each of the optical targets, thus establishing a trend regarding the expansion of the boiler water-cooled wall tube panel 7. By continuously controlling the laser emitting devices of the measuring platform 100 to measure during the boiler operation as it changes from the first load to the second load, a trend regarding the expansion of the water-cooled wall tube panel 7 can be established.

[0055] The following is a detailed explanation of the refined expansion monitoring method for the water-cooled wall of this boiler, using a specific example. (For reference...) Figures 3-6Taking the expansion monitoring of the boiler water-cooled wall tube screen of a 300MW subcritical unit in a power plant during the deep peak shaving process from 100% load to 15% load using the monitoring system of this embodiment as an example, the boiler of this unit adopts a four-corner tangential combustion method. There are six layers of burners, A, B, C, D, E, and F, arranged at the four corners of the furnace, with an elevation of 21m to 34m. When the boiler is at full load, burners B to F are used. Through the calculation of the heat load distribution inside the furnace and the measurement of the temperature field distribution, it is known that the elevation of the flame center is about 29m. When the boiler is at 15% load, only burner A is used, and the flame center drops to an elevation of about 23m. Therefore, the area with the greatest change in heat load of the water-cooled wall tube screen is between 23m and 29m. At the same time, due to the certain deflection of the flame inside the furnace, the heat load distribution of the unit's water-cooled wall tube screen is uneven in the horizontal direction, resulting in local high-temperature areas. During the peak shaving process, the heat load change in the high-temperature areas is relatively more obvious, which is the key area for tube screen expansion monitoring.

[0056] Taking the front wall water-cooled wall as an example, the specific steps are as follows:

[0057] Step 1: (See reference) Figure 4 and Figure 5 As shown, the area of ​​the boiler front wall water-cooled wall tube panel 7 with an elevation of 23m to 29m is selected and divided into several grid areas. Each grid area is a regular rectangle, which is called a large rectangular grid. The large rectangular grid in which the local high temperature area of ​​the water-cooled wall tube panel 7 is located in the horizontal direction is selected and denoted as grid ABCD.

[0058] Step 2: (See reference) Figure 6 As shown, the selected grid ABCD is divided into four equal parts to form four small rectangular grids, which are denoted as grid AEOH, grid EBFO, grid HOGD and grid OFCG, respectively.

[0059] Step 3: Install the measuring stage 100 at point O, the intersection of the four small rectangular grids, and install the optical targets at points E, F, G, and H respectively.

[0060] Step 4: When the boiler is at 100% load, the laser sources of the four laser emitting devices are turned on by the control device 113. The four laser beams pass through the corresponding beam apertures 105 and are incident on the target plates 111 of the corresponding optical targets. The distances from the measuring platform 100 to the four optical targets are measured by the data measurement module of the measuring platform 100 and recorded as d1, d2, d3 and d4 respectively. The data is transmitted to the control device 113 through the data transmission module of the measuring platform 100. The measurements show that d1 = 1006.23 mm, d2 = 2034.52 mm, d3 = 1013.44 mm, and d4 = 2021.33 mm.

[0061] Step 5: After reducing the boiler load to 15%, repeat step 4 above to measure the distances from the measuring platform 100 to the four optical targets, denoted as d1', d2', d3', and d4' respectively. The measurements show that d1' = 986.45 mm, d2' = 2011.47 mm, d3' = 998.75 mm, and d4' = 1999.87 mm.

[0062] Step 6: Calculate the distance changes measured in the selected local high-temperature area during boiler peak shaving, denoted as Δd1, Δd2, Δd3, and Δd4 respectively. Then:

[0063] △d1=d1′-d1, △d2=d2′-d2, △d3=d3′-d3, △d4=d4′-d4.

[0064] Substituting the above measurement results d1~d4 and d1'~d4' into the above formula, we obtain △d1=-19.78mm, △d2=-23.05mm, △d3=-14.69mm, and △d4=-21.46mm respectively. Then, the expansion amount of the selected local high temperature area of ​​the water-cooled wall tube panel 7 in the horizontal direction is △d2+△d4, that is, -44.51mm, and the expansion amount in the vertical direction is △d1+△d3, that is, -34.47mm.

[0065] Of course, during the process of reducing the boiler load from 100% to 15%, the above data can be continuously measured in real time to form a trend of expansion displacement data of the water-cooled wall tube panel 7.

[0066] Thus, the monitoring system and method of this embodiment have completed the monitoring of the expansion of the water-cooled wall tube panel of the boiler front wall in the power plant during the deep peak shaving process. According to this embodiment, selected areas of the water-cooled wall tube panels of the boiler furnace rear wall and side wall can be divided into grids, and the above-mentioned monitoring system and method can be used to monitor the expansion of the entire furnace water-cooled wall tube panel.

[0067] The refined expansion monitoring system and method for boiler water-cooled walls provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A refined expansion monitoring system for boiler water-cooled walls, characterized in that, It includes a measuring platform (100), a laser emitting device, a light target, and a control device (113), wherein the measuring platform (100) and the light target are arranged on the boiler water-cooled wall tube panel; The measuring stage (100) is equipped with four laser emitting devices. The angle between the light emission directions of any two adjacent laser emitting devices is 90°. The measuring stage (100) is also equipped with four beam holes (105). The four beam holes (105) correspond to the four laser emitting devices respectively, so that the light beam emitted by any laser emitting device passes through the corresponding beam hole (105) and is incident on the corresponding light target, thereby realizing distance measurement. The measuring station (100) is also equipped with a data transmission module, which is used to transmit the measured distance data to the control device (113), and the control device (113) is used to store and calculate the data. The method of applying the aforementioned refined expansion monitoring system for boiler water-cooled walls includes: Step S1: Select a monitoring area in the boiler water-cooled wall tube panel, and divide the monitoring area into multiple grid areas to be measured; Step S2: Select any of the grid regions to be tested and denote it as ABCD. Divide the selected grid region to be tested into four equal parts to form four small rectangular grids, which are respectively denoteed as grid AEOH, grid EBFO, grid HOGD and grid OFCG. Step S3: Arrange the measuring stage (100) at point O, the intersection of the four small rectangular grids, and arrange the light target at points E, F, G and H respectively; Step S4: At the first moment t0 of boiler operation, turn on the four laser emitting devices. The beam emitted by each laser emitting device passes through the corresponding beam hole (105) and is incident on the corresponding light target. The distances from the measuring platform (100) to each light target are measured and recorded as d1, d2, d3 and d4 respectively. Step S5: Repeat step S4 above at the second time t of boiler operation, and measure the distances from the measuring platform (100) to each of the optical targets at the second time t of boiler operation, and record them as d1', d2', d3' and d4' respectively; Step S6: Calculate the change in distance from the measuring stage (100) to each of the optical targets in the grid area to be measured at the second time t, compared to the first time t0. These changes are denoted as △d1, △d2, △d3, and △d4, respectively. △d1, △d2, △d3, and △d4 represent the expansion displacement of the four selected small rectangular grid areas. Specifically, △d1 represents the vertical expansion displacement of the AEOH and EBFO grid areas, △d2 represents the horizontal expansion displacement of the EBFO and OFCG grid areas, △d3 represents the vertical expansion displacement of the OFCG and HOGD grid areas, and △d4 represents the horizontal expansion displacement of the HOGD and AEOH grid areas.

2. The refined expansion monitoring system for boiler water-cooled walls according to claim 1, characterized in that, The bottom of the measuring platform (100) is provided with a support column (106), and the measuring platform (100) is fixed to the boiler water-cooled wall tube panel by the support column (106).

3. The refined expansion monitoring system for boiler water-cooled walls according to claim 1, characterized in that, The optical target includes a target handle (112) and a target plate (111). The target handle (112) is connected to the target plate (111), and the optical target is fixed to the boiler water-cooled wall tube panel through the target handle (112).

4. The refined expansion monitoring system for boiler water-cooled walls according to claim 1, characterized in that, The measuring accuracy of the measuring platform (100) is 0.1 mm.

5. The refined expansion monitoring system for boiler water-cooled walls according to claim 1, characterized in that, During boiler operation, multiple moments are selected as the boiler changes from the first load to the second load. At each moment, the above step S4 is repeated to measure the distance from the measuring platform (100) to each of the optical targets, so as to form the trend of the expansion of the boiler water-cooled wall tube screen.

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