A furnace water-cooled wall slag layer thickness calculation method based on image processing

Abstract

The present application provides a kind of furnace water-cooled wall slag layer thickness calculation method based on image processing, obtains the distance X of probe distance water-cooled wall side wall, the water-cooled wall side wall slag layer photo of probe oblique shooting;According to the definition of tangent angle and the principle of triangle similarity, establish furnace water-cooled wall slag layer thickness calculation model, including field of view calculation model, distance calculation model and thickness calculation model;The distance X of probe distance water-cooled wall side wall, the water-cooled wall side wall slag layer photo of probe oblique shooting is input into furnace water-cooled wall slag layer thickness calculation model, obtains the thickness of furnace water-cooled wall slag layer, realizes the purpose of visual judgment actual slagging condition of heating surface.

Description

Technical Field

[0001] This invention relates to the field of furnace water-cooled wall slagging monitoring technology, specifically to a method for calculating the thickness of slagging layer on furnace water-cooled walls based on image processing. Background Technology

[0002] The combustion of pulverized coal in the furnace is an extremely complex combustion process, accompanied by numerous physical and chemical reactions and involving many random events. When flue gas with a temperature higher than the ash melting point washes over the heating surface, the molten ash in the flue gas cools and adheres to the heating surface to form slag. This slag is not only affected by the furnace structure and furnace temperature level, but also closely related to the type of coal. However, due to the varying grades of coal, the wide range of variation, and the fact that boiler operation often deviates from the designed coal type, slag formation is common on the heating surfaces of various heat exchange components in the boiler.

[0003] Currently, power plants are equipped with long and short soot blowers, using high-pressure steam to periodically purge the heating surfaces. However, this timed and quantitative soot blowing cannot visually assess the actual slagging condition of the heating surfaces. The traditional fixed-cycle soot blowing strategy cannot meet the actual needs of ash and slag control under wide-load operation: insufficient soot blowing in some areas exacerbates slagging problems; while excessive soot blowing in other areas can damage the heating surfaces due to abrasion and thermal stress, shortening their lifespan and increasing unnecessary costs associated with soot blowing equipment.

[0004] Currently, there are two main methods for monitoring slagging on the water-cooled walls of furnaces: heat flow meter monitoring systems and acoustic monitoring methods. The heat flow meter monitoring system utilizes a completely clean heat flow meter and a contaminated heat flow meter that allows for ash deposit contamination. By analyzing the coupled electronic circuit information output from the two heat flow meters, a signal proportional to the ash deposition effect is provided to monitor furnace slagging. However, due to economic and maintenance considerations, thermocouples are only installed on the outer wall of the furnace and a few key locations on a small number of pipes. This limited number of measuring points cannot reflect the true condition of the furnace, thus lacking sufficient spatial resolution. The acoustic monitoring method, on the other hand, monitors slagging when the furnace is heated... When ash and slag accumulate on the surface, the heat exchange resistance increases, leading to an increase in the temperature of the outer wall of the slag layer, which in turn leads to an increase in the temperature of the flue gas in the furnace. Therefore, since the propagation speed of sound waves in a medium is related to the temperature of the medium, measuring the propagation speed of sound waves in the measured medium can reconstruct the temperature of the measured medium. This has verified the calculation and prediction of the fluid dynamic temperature distribution in pulverized coal boilers, and further determined the slag formation on the water-cooled walls. However, the working conditions inside the furnace are complex and variable, including various factors such as temperature, pressure, and gas composition. These factors can affect the propagation and reflection of sound waves, thus affecting the accuracy of the monitoring results. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for calculating the slag layer thickness of the furnace water-cooled wall based on image processing. By using a method for monitoring the oblique wall surface, the thickness of the water-cooled wall slag layer is obtained based on image processing of the slag layer, thereby achieving the purpose of visually judging the actual slagging condition of the heating surface.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for calculating the slag layer thickness of a furnace water-cooled wall based on image processing, the specific steps of which are as follows:

[0007] S1 acquires the distance X between the detector and the water-cooled wall sidewall, and an obliquely photographed image of the slag layer on the water-cooled wall sidewall.

[0008] S2 establishes a calculation model for the slag layer thickness of the furnace water-cooled wall based on the definition of tangent angle and the principle of triangle similarity. This model includes a field-of-view calculation model, a distance calculation model, and a thickness calculation model. The field-of-view calculation model is used to obtain the field-of-view angles corresponding to the top and bottom of the slag layer based on the slag layer photograph. The distance calculation model is used to obtain the distances from the top and bottom of the slag layer to the detector inside the furnace based on the field-of-view angles corresponding to the top and bottom of the slag layer using the definition of tangent angle. The thickness calculation model is used to obtain the thickness of the slag layer of the furnace water-cooled wall based on the distances from the top and bottom of the slag layer to the detector inside the furnace using the principle of triangle similarity.

[0009] S3 inputs the distance X between the detector and the water-cooled wall sidewall, and the obliquely photographed image of the slag layer on the water-cooled wall sidewall, into the furnace water-cooled wall slag layer thickness calculation model to obtain the furnace water-cooled wall slag layer thickness.

[0010] Furthermore, the field of view calculation model specifically includes:

[0011] 1) Obtain the degree 'a' of the detector's field of view occupied by each pixel in the slag layer image;

[0012] 2) Obtain the pixel n1 at the bottom of the slag layer at a distance of 0° from the field of view, obtain the angle an1 formed by the bottom of the slag layer, the detector and the 0° position of the field of view, obtain the number of pixels n2 occupied by the thickness of the slag layer, and obtain the angle an2 formed by the top of the slag layer, the detector and the bottom of the slag layer.

[0013] 3) Obtain the angle θ between the line containing the detector's field of view of 0° and the line connecting the detector and the water-cooled wall sidewall;

[0014] 4) Add angle an1 to angle θ to obtain the field of view θ1 formed by the bottom of the slag layer and the point on the water-cooled wall where the detector is perpendicularly projected; add angle an1, angle an2 and angle θ to obtain the field of view θ2 formed by the top of the slag layer and the point on the water-cooled wall where the detector is perpendicularly projected.

[0015] Furthermore, in step 1), the degree a = field of view / number of pixels.

[0016] Furthermore, the distance calculation model specifically includes:

[0017] 1) Obtain the field of view angles θ1 and θ2, and the distance X between the detector and the water-cooled wall sidewall;

[0018] 2) Using the definition of tangent angle, based on the field of view angle θ1 and the distance X between the detector and the side wall of the water-cooled wall, the distance L1 between the bottom of the slag layer and the projection of the detector onto the side wall of the water-cooled wall is obtained;

[0019] 3) Using the definition of tangent angle, based on the field of view angle θ2 and the distance X between the detector and the water-cooled wall sidewall, the distance L2 between the intersection of the line connecting the detector and the top of the slag layer on the water-cooled wall sidewall and the projection of the detector on the water-cooled wall sidewall is obtained.

[0020] Furthermore, in step 2), the distance between the bottom of the slag layer and the projection of the detector onto the water-cooled wall sidewall is L1 = tan(θ1)·X; in step 3, the distance between the intersection of the line connecting the detector and the top of the slag layer on the water-cooled wall sidewall and the projection of the detector onto the water-cooled wall sidewall is L2 = tan(θ2)·X.

[0021] Furthermore, the thickness calculation model specifically includes:

[0022] 1) Obtain distances L1, L2, and X from the detector to the water-cooled wall sidewall;

[0023] 2) Using the principle of similar triangles, we can obtain L / X = (L2-L1) / L2, and thus the thickness of the slag layer L.

[0024] Furthermore, the detector employs mid-wave infrared thermal imaging.

[0025] This invention provides a furnace water-cooled wall slag layer thickness calculation system based on image processing, comprising:

[0026] The data acquisition module is used to acquire the distance X between the detector and the water-cooled wall sidewall, and the obliquely photographed image of the slag layer on the water-cooled wall sidewall.

[0027] The calculation model building module is used to establish a calculation model for the slag layer thickness of the furnace water-cooled wall based on the definition of tangent angle and the principle of triangle similarity. This includes a field-of-view calculation model, a distance calculation model, and a thickness calculation model. The field-of-view calculation model is used to obtain the corresponding field-of-view angles for the top and bottom of the slag layer based on photographs of the slag layer. The distance calculation model is used to obtain the distances from the top and bottom of the slag layer to the detector inside the furnace based on the corresponding field-of-view angles of the top and bottom of the slag layer, using the definition of tangent angle. The thickness calculation model is used to obtain the thickness of the slag layer in the furnace water-cooled wall based on the distances from the top and bottom of the slag layer to the detector inside the furnace, using the principle of triangle similarity.

[0028] The data transmission calculation module is used to input the distance X between the detector and the water-cooled wall sidewall and the slag layer photo of the water-cooled wall sidewall taken by the detector at an angle into the furnace water-cooled wall slag layer thickness calculation model to obtain the furnace water-cooled wall slag layer thickness.

[0029] The present invention also provides a terminal device, the terminal device comprising: a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, it implements the steps in the above-described image processing-based furnace water-cooled wall slag layer thickness calculation method; or, when the processor executes the computer program, it implements the functions of each module in the above-described image processing-based furnace water-cooled wall slag layer thickness calculation system.

[0030] The present invention also provides a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, it implements the steps in the above-described image processing-based furnace water-cooled wall slag layer thickness calculation method; or, when the processor executes the computer program, it implements the functions of each module in the above-described image processing-based furnace water-cooled wall slag layer thickness calculation system.

[0031] Compared with the prior art, the present invention has at least the following beneficial effects:

[0032] This invention provides a method for calculating the slag layer thickness of furnace water-cooled walls based on image processing. By using a detector to obliquely monitor the sidewalls of the water-cooled walls and acquiring photographs of the slag layer, the image of the slag layer is processed using a model for calculating the slag layer thickness. The thickness of the slag layer is obtained based on the definition of tangent angle and the principle of triangle similarity. This method can visualize and judge the actual slagging condition of the heating surface and can also accurately calculate the slag thickness in different slagging areas. It not only has high spatial resolution but is also unaffected by changes in furnace operating conditions.

[0033] Compared to traditional thermocouple slag monitoring methods, the method of this invention is based on visual monitoring of the slag layer, has high spatial resolution, and can accurately calculate the slag layer thickness. Compared to acoustic monitoring methods, this method is less affected by changes in furnace operating conditions. Acoustic monitoring methods can only roughly obtain the location of slag formation and cannot achieve visual monitoring. They are also severely affected by flue gas and operating conditions in the furnace. This calculation method is not limited by coal type and is suitable for wide-load operation. Attached Figure Description

[0034] Figure 1 Images of slagging monitoring on water-cooled walls;

[0035] Figure 2 A schematic diagram illustrating the calculation of slag layer thickness in this invention. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0037] Because existing slagging monitoring methods are difficult to provide specific slagging thickness, thermocouple methods have too low spatial resolution and the equipment is difficult to maintain; acoustic monitoring methods are severely limited by changes in the internal working conditions of the furnace. This invention proposes a method for calculating the slagging thickness of the furnace water-cooled wall based on image processing. The specific steps are as follows:

[0038] The first step is to install a detector inside the furnace based on the combustion characteristics inside the furnace. The detector monitors the water-cooled wall sidewall by using an oblique viewing method to obtain a photograph of the slag layer on the water-cooled wall sidewall.

[0039] Let O be the midpoint of the detector lens; let A be the intersection of the line connecting the midpoint of the detector lens and the side wall it is detecting; let B be the intersection of the line containing the 0° field of view of the detector and the side wall; let C be the bottom point of the slag layer and E be the top point of the slag layer; let D be the intersection of the line connecting the midpoint O of the detector lens and the top E of the slag layer and the side wall where they are located.

[0040] The horizontal distance OA between the detector and the side wall it detects is obtained as X; the angle BOA between the detector's field of view and the vertical direction is obtained as θ.

[0041] Preferably, using a mid-wave infrared thermal imager and monitoring the sidewalls of the water-cooled wall by oblique viewing can largely avoid the impact of flame fly ash on the imaging effect.

[0042] The second step is to obtain the field of view of the detector and the number of pixels in the water-cooled wall slag layer image, and obtain the degree of the field of view occupied by each pixel. The angle 'a' occupied by each pixel is equal to the field of view / the number of pixels.

[0043] The third step is to obtain the pixel n1 at the bottom of the slag layer at a distance of 0° from the field of view (i.e. the pixel between points B and C). Based on the degree of the field of view occupied by each pixel, the angle ∠COB corresponding to the bottom of the slag layer is obtained as a·n1. Let the field of view angle ∠COA be θ1, and we get θ1 = a·n1 + θ.

[0044] The fourth step is to obtain the number of pixels n2 occupied by the thickness of the slag layer, and to find the angle ∠DOC corresponding to the thickness of the slag layer as a·n2. Let the field of view angle ∠DOA be the field of view angle θ2, and get θ2=a·n2+a·n1+θ;

[0045] The fifth step is to obtain the field of view angles θ1 and θ2. Based on geometric relationships, the distance L1 between the bottom of the slag layer and the detector (i.e., the length of line segment AC) and the distance L2 between the detector and the intersection of the line connecting the midpoint of the detector lens and the top of the slag layer with the side wall (i.e., the length of line segment AD) are calculated. Specifically:

[0046] L1 = tan(θ1)·X

[0047] L2=tan(θ2)·X

[0048] Step 6: Since the straight line EC along the slag layer thickness direction is parallel to the horizontal distance OA between the detector and the side wall it detects, triangles DCE and DOA are similar triangles. Therefore, based on the similarity of triangles, we have L / X = (L2-L1) / L2. The final formula for calculating the slag layer thickness L is: L = (tanθ2-tanθ1) / tanθ2·X.

[0049] An embodiment of the present invention provides a furnace water-cooled wall slag layer thickness calculation system based on image processing, comprising:

[0050] The data acquisition module is used to acquire the distance X between the detector and the water-cooled wall sidewall, and the obliquely photographed image of the slag layer on the water-cooled wall sidewall.

[0051] The calculation model building module is used to establish a calculation model for the slag layer thickness of the furnace water-cooled wall based on the definition of tangent angle and the principle of triangle similarity. This includes a field-of-view calculation model, a distance calculation model, and a thickness calculation model. The field-of-view calculation model is used to obtain the corresponding field-of-view angles for the top and bottom of the slag layer based on photographs of the slag layer. The distance calculation model is used to obtain the distances from the top and bottom of the slag layer to the detector inside the furnace based on the corresponding field-of-view angles of the top and bottom of the slag layer, using the definition of tangent angle. The thickness calculation model is used to obtain the thickness of the slag layer in the furnace water-cooled wall based on the distances from the top and bottom of the slag layer to the detector inside the furnace, using the principle of triangle similarity.

[0052] The data transmission calculation module is used to input the distance X between the detector and the water-cooled wall sidewall and the slag layer photo of the water-cooled wall sidewall taken by the detector at an angle into the furnace water-cooled wall slag layer thickness calculation model to obtain the furnace water-cooled wall slag layer thickness.

[0053] One embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the above-described image processing-based furnace water-cooled wall slag layer thickness calculation method; or, when the processor executes the computer program, it implements the functions of each module in the above-described image processing-based furnace water-cooled wall slag layer thickness calculation system.

[0054] The computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention.

[0055] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0056] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0057] The memory can be used to store the computer program and / or module. The processor implements various functions of the terminal device by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0058] If the modules / units integrated in the terminal device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.

[0059] Based on this understanding, all or part of the processes in the above-described embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium. When executed by a processor, the computer program can implement the steps of the above-described method for calculating the slag layer thickness of a furnace water-cooled wall based on image processing. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms.

[0060] The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium may be appropriately added to or subtracted according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media may not include electrical carrier signals and telecommunication signals.

[0061] An embodiment of the present invention provides a specific example of a method for calculating the slag layer thickness of a furnace water-cooled wall based on image processing, as detailed below:

[0062] First step, such as Figure 1As shown, the slag layer on the water-cooled wall sidewall was obtained by using the detector's oblique viewing method to monitor the sidewall.

[0063] The second step involves calculating the slag thickness through geometric analysis of the detector's field of view. An example calculation is shown below:

[0064] like Figure 2 As shown, the detector lens is inserted into the furnace for monitoring. The distance X between the detector lens and the side wall is 50 cm, the field of view is 90°, and the detector has 1268 pixels horizontally. Therefore, one pixel occupies 0.071°.

[0065] The number of pixels from the bottom of the slag layer to the 0° field of view is 48, corresponding to a field of view of 3.408°, i.e., θ1 = 33.408°. The number of pixels occupied by the thickness of the slag layer is 15, corresponding to a field of view of 1.065°, i.e., θ2 = 34.473°.

[0066] According to the definition of tangent angle, L1 / 50 = tan(33.408°) = 0.659, that is, L1 = 32.95; L2 / 50 = tan(34.329°) = 0.686, that is, L2 = 34.33.

[0067] Based on the similarity of triangles, L / 50 = (L2 - L1) / L2, we can calculate the thickness of the slag layer L = 2.01, so the thickness of the slag layer is 2.01 cm.

Claims

1. A method for calculating the slag layer thickness of a furnace water-cooled wall based on image processing, characterized in that, The specific steps are as follows: S1 acquires the distance X between the detector and the water-cooled wall sidewall, and an obliquely photographed image of the slag layer on the water-cooled wall sidewall. S2 establishes a calculation model for the thickness of the slag layer in the furnace water-cooled wall based on the definition of tangent angle and the principle of triangle similarity. The model includes a field of view calculation model, a distance calculation model, and a thickness calculation model. The field of view angle calculation model is used to obtain the corresponding field of view angles at the top and bottom of the slag layer based on the slag layer photograph. The distance calculation model is used to obtain the distance from the top and bottom of the slag layer to the detector inside the furnace based on the field of view corresponding to the top and bottom of the slag layer using the definition of tangent angle; the thickness calculation model is used to obtain the thickness of the slag layer in the furnace water-cooled wall based on the distance from the top and bottom of the slag layer to the detector inside the furnace using the principle of triangle similarity. S3 inputs the distance X between the detector and the water-cooled wall sidewall and the photo of the slag layer on the water-cooled wall sidewall taken by the detector at an angle into the furnace water-cooled wall slag layer thickness calculation model to obtain the furnace water-cooled wall slag layer thickness. The field of view calculation model specifically includes: 1) Obtain the degree of the detector's field of view occupied by each pixel in the slag layer image. ; 2) Obtain pixel n1 at the bottom of the slag layer at a distance of 0° from the field of view, and obtain the angle between the bottom of the slag layer, the detector, and the 0° position of the field of view. Obtain the number of pixels n2 occupied by the slag layer thickness, and obtain the angle formed by the top of the slag layer, the detector, and the bottom of the slag layer. ; 3) Obtain the angle between the line containing the detector's field of view of 0° and the line connecting the detector and the water-cooled wall sidewall. ; 4) Angle With angle The sum of these values ​​yields the field of view formed by the bottom of the slag layer, the detector, and the point on the water-cooled wall sidewall where the detector's perpendicular projection is projected. ; Angle ,angle With angle The sum of these values ​​yields the field of view formed by the top of the slag layer, the detector, and the point on the water-cooled wall sidewall where the detector's perpendicular projection is projected. ; The distance calculation model specifically includes: 1) Obtain the field of view and X is the distance X between the detector and the sidewall of the water-cooled wall. 2) Using the definition of tangent angle, based on the field of view angle The distance X between the detector and the water-cooled wall sidewall is used to obtain the distance between the bottom of the slag layer and the projection of the detector onto the water-cooled wall sidewall. ; 3) Using the definition of tangent angle, based on the field of view angle The distance X between the detector and the water-cooled wall sidewall is used to obtain the distance between the intersection of the line connecting the detector and the top of the slag layer on the water-cooled wall sidewall and the projection of the detector onto the water-cooled wall sidewall. ; The thickness calculation model specifically includes: 1) Obtain distance ,distance The distance X between the detector and the sidewall of the water-cooled wall; 2) Obtain by using the principle of similar triangles The thickness L of the slag layer is obtained.

2. The method for calculating the slag layer thickness of a furnace water-cooled wall based on image processing according to claim 1, characterized in that, In step 1), the degree .

3. The method for calculating the slag layer thickness of a furnace water-cooled wall based on image processing according to claim 1, characterized in that, In step 2), the distance between the bottom of the slag layer and the projection of the detector onto the water-cooled wall sidewall is... In step 3): the distance between the intersection of the line connecting the detector and the top of the slag layer on the side wall of the water-cooled wall and the projection of the detector onto the side wall of the water-cooled wall. .

4. The method for calculating the slag layer thickness of a furnace water-cooled wall based on image processing according to claim 1, characterized in that, The detector uses mid-wave infrared thermal imaging.

5. A furnace water-cooled wall slag layer thickness calculation system based on image processing, characterized in that, The system comprising the image processing-based method for calculating the slag layer thickness of a furnace water-cooled wall according to any one of claims 1 to 4, wherein the system includes: The data acquisition module is used to acquire the distance X between the detector and the water-cooled wall sidewall, and the obliquely photographed image of the slag layer on the water-cooled wall sidewall. The calculation model building module is used to establish a calculation model for the slag layer thickness of the furnace water-cooled wall based on the definition of tangent angle and the principle of triangle similarity. This includes a field-of-view calculation model, a distance calculation model, and a thickness calculation model. The field-of-view calculation model is used to obtain the corresponding field-of-view angles for the top and bottom of the slag layer based on photographs of the slag layer. The distance calculation model is used to obtain the distances from the top and bottom of the slag layer to the detector inside the furnace based on the corresponding field-of-view angles of the top and bottom of the slag layer, using the definition of tangent angle. The thickness calculation model is used to obtain the thickness of the slag layer in the furnace water-cooled wall based on the distances from the top and bottom of the slag layer to the detector inside the furnace, using the principle of triangle similarity. The data transmission calculation module is used to input the distance X between the detector and the water-cooled wall sidewall and the slag layer photo of the water-cooled wall sidewall taken by the detector at an angle into the furnace water-cooled wall slag layer thickness calculation model to obtain the furnace water-cooled wall slag layer thickness.

6. A terminal device, the terminal device comprising: A processor, a memory, and a computer program stored in the memory and executable on the processor, characterized in that, when the processor executes the computer program, it implements the steps in the image processing-based furnace water-cooled wall slag layer thickness calculation method according to any one of claims 1 to 4; or, when the processor executes the computer program, it implements the functions of each module in the image processing-based furnace water-cooled wall slag layer thickness calculation system according to claim 5.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps in the image processing-based furnace water-cooled wall slag layer thickness calculation method according to any one of claims 1 to 4. Alternatively, when the processor executes the computer program, it implements the functions of each module in the image processing-based furnace water-cooled wall slag layer thickness calculation system as described in claim 5.

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