Air leakage monitoring system and method for air preheater

Abstract

The invention relates to the technical field of air preheaters, and discloses an air preheater air leakage monitoring system and method, and the system comprises an obtaining module which is used for obtaining an air preheater gap region image, and setting an air leakage region image according to the air preheater gap region image; the detection module is used for carrying out edge detection on the air leakage area image and determining a direct air leakage characteristic value according to an edge detection result of the air leakage area image; the calculation module is used for acquiring the rotor rotating speed of the current air preheater and determining an air leakage danger value according to the rotor rotating speed of the current air preheater and the direct air leakage characteristic value; and the early warning module is used for determining the air leakage grade according to the air leakage danger value and carrying out early warning on the air preheater according to the air leakage grade. The air leakage grade of the air preheater can be detected in real time, and economic losses caused by air leakage of the air preheater are effectively reduced.

Description

Technical Field

[0001] This application relates to the technical field of air preheaters, and more specifically, to a system and method for monitoring air leakage in an air preheater. Background Art

[0002] Rotary air preheaters are commonly used in large and medium-sized power station boilers, and the air leakage rate is one of their important economic indicators. Effectively controlling the air leakage rate of the air preheater can achieve energy-saving benefits in two aspects: reducing the power consumption of primary air fans, forced draft fans, and induced draft fans, and improving the boiler efficiency.

[0003] In the prior art, for the measurement of the air leakage rate of the air preheater, only the air leakage rate can be measured through regular air leakage tests, with low measurement efficiency and poor economy. Summary of the Invention

[0004] The present invention provides a system and method for monitoring air leakage in an air preheater to solve the problems of low measurement efficiency and poor economy of air leakage measurement in the prior art, including:

[0005] An acquisition module for acquiring an image of the clearance area of the air preheater and setting an air leakage area image according to the image of the clearance area of the air preheater;

[0006] A detection module for performing edge detection on the air leakage area image and determining a direct air leakage characteristic value according to the edge detection result of the air leakage area image;

[0007] A calculation module for obtaining the rotor speed of the current air preheater and determining an air leakage risk value according to the rotor speed of the current air preheater and the direct air leakage characteristic value;

[0008] An early warning module for determining an air leakage level according to the air leakage risk value and giving an early warning to the air preheater according to the air leakage level.

[0009] Further, the acquisition module setting the air leakage area image according to the image of the clearance area of the air preheater includes:

[0010] Performing grayscale processing on the image of the clearance area of the air preheater to obtain a grayscale image of the clearance area;

[0011] Obtaining a preset grid, and segmenting the grayscale image of the clearance area according to the preset grid to obtain a plurality of sub-grayscale images of the clearance area;

[0012] Obtaining the average grayscale value of the pixel points in the sub-grayscale image of the clearance area, and determining the similarity of the adjacent sub-grayscale images of the clearance area according to the average grayscale values of the pixel points of the adjacent sub-grayscale images of the clearance area;

[0013] Merge the grayscale images of each sub-gap region according to the similarity of the grayscale images of adjacent sub-gap regions to obtain a merged grayscale image of the gap region;

[0014] Calculate the possibility of the air leakage region of the merged grayscale image of the gap region, and set the merged grayscale image of the gap region with the possibility of air leakage region greater than the first preset threshold as the air leakage region image.

[0015] Further, the determining the similarity of the grayscale images of adjacent sub-gap regions according to the average grayscale value of the pixel points of the grayscale images of adjacent sub-gap regions includes:

[0016] Calculate the difference between the average grayscale values of the pixel points of the grayscale images of adjacent sub-gap regions to obtain a grayscale difference;

[0017] Obtain a preset grayscale range, and segment the pixel points of the grayscale image of the sub-gap region according to the preset grayscale range;

[0018] Count the number of segments of the grayscale image of the sub-gap region, and calculate the difference between the number of segments of the grayscale images of adjacent sub-gap regions;

[0019] Determine the similarity of the grayscale images of adjacent sub-gap regions according to the grayscale difference and the difference in the number of segments of the grayscale images of adjacent sub-gap regions.

[0020] Further, the calculating the possibility of the air leakage region of the merged grayscale image of the gap region includes:

[0021] Segment the pixel points of the merged grayscale image of the gap region according to the preset grayscale range, and calculate the ratio of the grayscale value of the pixel points in each merged grayscale image of the gap region after segmentation to the preset air leakage grayscale value;

[0022] Count the average value of the ratios of the grayscale values of the pixel points of the merged grayscale image of the gap region to the preset air leakage grayscale value, and determine the possibility of the air leakage region of the merged grayscale image of the gap region according to the average value of the ratios.

[0023] Further, the detecting module performs edge detection on the air leakage region image, and determines the direct air leakage feature value according to the edge detection result of the air leakage region image, including:

[0024] Perform edge detection on the air leakage region image based on the canny edge detection algorithm to obtain an air leakage edge;

[0025] Perform triangular fitting on the air leakage edge, and calculate the area value of the fitted triangle;

[0026] Real-time detect the area value of the fitted triangle, and draw an area change curve according to the change situation of the area value of the fitted triangle;

[0027] Perform curve fitting on the area change curve, and determine the predicted time when the area value of the fitted triangle reaches the second preset threshold according to the curve fitting result;

[0028] Determine the direct air leakage characteristic value according to the predicted time when the area value of the fitted triangle reaches the second preset threshold.

[0029] Further, the calculation module determines the air leakage risk value according to the rotor speed of the current air preheater and the direct air leakage characteristic value, including:

[0030] Calculate the difference between the rotor speed of the current air preheater and the preset allowable rotor speed, and perform normalization processing on the difference between the rotor speed of the current air preheater and the preset allowable rotor speed to obtain the air leakage characteristic value carrying;

[0031] Determine the air leakage risk value of the current air preheater according to the air leakage characteristic value carrying and the direct air leakage characteristic value.

[0032] Further, the determining the air leakage risk value of the current air preheater according to the air leakage characteristic value carrying and the direct air leakage characteristic value includes:

[0033] Determine the air leakage risk value according to the air leakage risk value calculation formula, and the air leakage risk value calculation formula is specifically,

[0034]

[0035] where D is the air leakage risk value, T is the direct air leakage characteristic value, N is the air leakage characteristic value carrying, R is the preset range adjustment value, and exp is the natural exponential function.

[0036] Further, the warning module determines the air leakage level according to the air leakage risk value, including:

[0037] Obtain the preset air leakage standard value, and calculate the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value;

[0038] Judge whether the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value is greater than the third preset threshold. If the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value is greater than the third preset threshold, set the first-level air leakage level;

[0039] If the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value is less than or equal to the third preset threshold, judge whether the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value is greater than the fourth preset threshold;

[0040] If the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value is greater than the fourth preset threshold, set the second level as the air leakage level;

[0041] If the difference between the current air leakage risk value of the air preheater and the preset air leakage standard value is less than or equal to the fourth preset threshold, the third level is set as the air leakage level.

[0042] Furthermore, the warning module warns the air preheater according to the air leakage level, including:

[0043] When the air leakage level is the third level, no air leakage warning is given to the air preheater;

[0044] When the air leakage level is the second level, a slight air leakage warning is given to the air preheater;

[0045] When the air leakage level is the first level, a serious air leakage warning is given to the air preheater.

[0046] To achieve the above object, the present invention also provides a method for monitoring air leakage of an air preheater, the method including:

[0047] Obtain an image of the gap area of the air preheater, and set an air leakage area image according to the image of the gap area of the air preheater;

[0048] Perform edge detection on the air leakage area image, and determine a direct air leakage characteristic value according to the edge detection result of the air leakage area image;

[0049] Obtain the rotor speed of the current air preheater, and determine the air leakage risk value according to the rotor speed of the current air preheater and the direct air leakage characteristic value;

[0050] Determine the air leakage level according to the air leakage risk value, and warn the air preheater according to the air leakage level.

[0051] The beneficial effects of the present invention are as follows:

[0052] By applying the above technical solutions, the present invention realizes air leakage detection of the air preheater by obtaining the air leakage area image of the air preheater in real time, and calculates the carried air leakage amount through the rotor speed, so as to realize real-time monitoring of the air leakage level of the air preheater, and at the same time timely warn the air preheater according to the air leakage level, effectively reducing the economic losses caused by the air leakage of the air preheater. Description of the Drawings

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for description in the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained according to these drawings.

[0054] Figure 1The overall structure diagram of an air preheater air leakage monitoring system proposed by an embodiment of the present invention is shown;

[0055] Figure 2 The schematic flow chart of an air preheater air leakage monitoring method proposed by an embodiment of the present invention is shown. Specific embodiments

[0056] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0057] An embodiment of the present application provides an air preheater air leakage monitoring system, as Figure 1 shown, including:

[0058] An acquisition module, configured to acquire an image of the clearance area of the air preheater and set an air leakage area image according to the image of the clearance area of the air preheater; a detection module, configured to perform edge detection on the air leakage area image and determine a direct air leakage characteristic value according to the edge detection result of the air leakage area image; a calculation module, configured to acquire the rotor speed of the current air preheater and determine an air leakage risk value according to the rotor speed of the current air preheater and the direct air leakage characteristic value; an early warning module, configured to determine an air leakage level according to the air leakage risk value and give an early warning to the air preheater according to the air leakage level.

[0059] In this embodiment, the acquisition module is used to monitor in real time the image of the clearance area between the sector plate and the rotor radial seal plate of the air preheater, so as to extract the air leakage area image. The direct air leakage characteristic value is calculated through the air leakage area image. At the same time, the carried air leakage volume of the air preheater is obtained through the rotor speed of the air preheater, so as to obtain the air leakage risk value and determine the air leakage level, and an early warning of the air preheater is realized based on the air leakage level.

[0060] In some embodiments of the present application, the obtaining module sets the air leakage area image according to the air preheater gap area image, including: performing grayscale processing on the air preheater gap area image to obtain a gap area grayscale image; obtaining a preset grid, and segmenting the gap area grayscale image according to the preset grid to obtain a plurality of sub-gap area grayscale images; obtaining the average grayscale value of the pixel points in the sub-gap area grayscale image, and determining the similarity between adjacent sub-gap area grayscale images according to the average grayscale values of the pixel points in the adjacent sub-gap area grayscale images; merging the sub-gap area grayscale images according to the similarity between the adjacent sub-gap area grayscale images to obtain a merged gap area grayscale image; calculating the air leakage area possibility of the merged gap area grayscale image, and setting the merged gap area grayscale image with an air leakage area possibility greater than a first preset threshold as the air leakage area image.

[0061] In this embodiment, the gap area grayscale image is segmented into a plurality of sub-gap area grayscale images by a preset grid, and the adjacent sub-gap area grayscale images with a similarity greater than a preset similarity threshold are merged, and the similarity of the adjacent sub-gap area grayscale images after merging is recalculated to obtain the final merged gap area grayscale image, so as to screen out the air leakage area image therefrom through the air leakage area possibility.

[0062] In some embodiments of the present application, determining the similarity between adjacent sub-gap area grayscale images according to the average grayscale values of the pixel points in the adjacent sub-gap area grayscale images includes: calculating the difference between the average grayscale values of the pixel points in the adjacent sub-gap area grayscale images to obtain a grayscale difference; obtaining a preset grayscale range, and segmenting the pixel points in the sub-gap area grayscale image according to the preset grayscale range; counting the segmentation quantity of the sub-gap area grayscale image, and calculating the difference between the segmentation quantities of the adjacent sub-gap area grayscale images; determining the similarity between the adjacent sub-gap area grayscale images according to the grayscale difference and the difference between the segmentation quantities of the adjacent sub-gap area grayscale images.

[0063] In this embodiment, a plurality of grayscale ranges are preset, and the sub-gap area grayscale image is segmented into a plurality of image blocks by the plurality of preset grayscale ranges, so as to obtain the segmentation quantity. The larger the segmentation quantity is, the more complex the sub-gap area grayscale image is. The similarity between the adjacent sub-gap area grayscale images is determined by the sum value of the grayscale difference and the segmentation quantity difference. The smaller the sum value of the difference is, the higher the corresponding similarity is.

[0064] In some embodiments of the present application, calculating the possibility of a leakage area in the gray-scale image of the combined gap area includes: segmenting the pixel points of the gray-scale image of the combined gap area according to a preset gray-scale range, and calculating the ratio of the gray-scale value of the pixel points in each gray-scale image of the combined gap area after segmentation to the preset leakage gray-scale value; statistically calculating the average value of the ratios of the gray-scale values of the pixel points in the gray-scale image of the combined gap area to the preset leakage gray-scale value, and determining the possibility of the leakage area in the gray-scale image of the combined gap area according to the average value of the ratios.

[0065] In this embodiment, the possibility of the leakage area is determined by the average value of the ratios of the gray-scale values of the pixel points in multiple gray-scale images of the combined gap area after segmentation. The closer the ratio is to 1, the greater the possibility of the leakage area in the gray-scale image of the combined gap area.

[0066] In some embodiments of the present application, the detection module performs edge detection on the leakage area image and determines the direct leakage characteristic value according to the edge detection result of the leakage area image, including: performing edge detection on the leakage area image based on the canny edge detection algorithm to obtain a leakage edge; performing triangular fitting on the leakage edge and calculating the area value of the fitted triangle; detecting the area value of the fitted triangle in real time, and drawing an area change curve according to the change situation of the area value of the fitted triangle; performing curve fitting on the area change curve, and determining the predicted time when the area value of the fitted triangle reaches a second preset threshold according to the curve fitting result; determining the direct leakage characteristic value according to the predicted time when the area value of the fitted triangle reaches the second preset threshold.

[0067] In this embodiment, curve fitting is performed on the area change curve of the fitted triangle area value of the leakage edge based on the least squares method, the time when the leakage area reaches the danger value is predicted through the curve fitting result, and the direct leakage characteristic value is obtained after normalizing the corresponding predicted time.

[0068] In some embodiments of the present application, the calculation module determines the leakage danger value according to the rotor speed of the current air preheater and the direct leakage characteristic value, including: calculating the difference between the rotor speed of the current air preheater and the preset allowable rotor speed, normalizing the difference between the rotor speed of the current air preheater and the preset allowable rotor speed to obtain a leakage characteristic value carrying; determining the leakage danger value of the current air preheater according to the leakage characteristic value carrying and the direct leakage characteristic value.

[0069] In this embodiment, the leakage characteristic value carrying is calculated through the difference between the rotor speed of the current air preheater and the preset allowable rotor speed, and the leakage danger value of the current air preheater is calculated by combining the leakage characteristic value carrying and the direct leakage characteristic value.

[0070] In some embodiments of the present application, determining the air leakage risk value of the current air preheater based on the air leakage characteristic value and the direct air leakage characteristic value includes: determining the air leakage risk value according to the air leakage risk value calculation formula, and the specific air leakage risk value calculation formula is

[0071]

[0072] where D is the air leakage risk value, T is the direct air leakage characteristic value, N is the carried air leakage characteristic value, R is the preset range adjustment value, and exp is the natural exponential function.

[0073] In this embodiment, the carried air leakage characteristic value N is adjusted to a suitable range through the preset range adjustment value R, so as to calculate the air leakage risk value D.

[0074] In some embodiments of the present application, the warning module determines the air leakage level according to the air leakage risk value, including: obtaining the preset air leakage standard value, and calculating the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value; judging whether the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value is greater than the third preset threshold. If the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value is greater than the third preset threshold, the first-level air leakage level is set; if the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value is less than or equal to the third preset threshold, it is judged whether the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value is greater than the fourth preset threshold; if the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value is greater than the fourth preset threshold, the second level is set as the air leakage level; if the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value is less than or equal to the fourth preset threshold, the third level is set as the air leakage level.

[0075] In this embodiment, the air leakage level of the air preheater is evaluated through the difference between the air leakage risk value of the current air preheater and the preset air leakage standard value. The larger the difference, the higher the corresponding air leakage level ranking, and the more serious the air leakage situation.

[0076] In some embodiments of the present application, the warning module gives a warning to the air preheater according to the air leakage level, including: when the air leakage level is the third level, no air leakage warning is given to the air preheater; when the air leakage level is the second level, a slight air leakage warning is given to the air preheater; when the air leakage level is the first level, a serious air leakage warning is given to the air preheater.

[0077] In this embodiment, an air leakage warning is given by evaluating the air leakage level of the air preheater, and the serious situation of the air leakage is notified to the operation and maintenance personnel in time, which is convenient for the operation and maintenance personnel to deal with the air leakage situation in time and reduce the economic loss caused by the air leakage of the air preheater.

[0078] Based on the same inventive concept, such as Figure 2 shown, the present invention also provides a method for monitoring air leakage of an air preheater, the method comprising:

[0079] S101, obtaining an image of the clearance area of the air preheater, and setting an air leakage area image according to the image of the clearance area of the air preheater;

[0080] S102, performing edge detection on the air leakage area image, and determining a direct air leakage characteristic value according to the edge detection result of the air leakage area image;

[0081] S103, obtaining the rotor speed of the current air preheater, and determining an air leakage risk value according to the rotor speed of the current air preheater and the direct air leakage characteristic value;

[0082] S104, determining an air leakage level according to the air leakage risk value, and giving an early warning to the air preheater according to the air leakage level.

[0083] By applying the above technical solutions, the present invention includes an acquisition module for obtaining an image of the clearance area of the air preheater and setting an air leakage area image according to the image of the clearance area of the air preheater; a detection module for performing edge detection on the air leakage area image and determining a direct air leakage characteristic value according to the edge detection result of the air leakage area image; a calculation module for obtaining the rotor speed of the current air preheater and determining an air leakage risk value according to the rotor speed of the current air preheater and the direct air leakage characteristic value; and an early warning module for determining an air leakage level according to the air leakage risk value and giving an early warning to the air preheater according to the air leakage level. The present invention can detect the air leakage level of the air preheater in real time and effectively reduce the economic losses caused by the air leakage of the air preheater.

[0084] Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be implemented by hardware or by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present invention can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.), including several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in various implementation scenarios of the present invention.

[0085] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims

1. An air preheater air leakage monitoring system, characterized in that: include: An acquisition module, used for acquiring an image of a gap area of ​​an air preheater, and setting an image of an air leakage area according to the image of the gap area of ​​the air preheater; A detection module is used to perform edge detection on the air leakage area image and determine the direct air leakage characteristic value according to the edge detection result of the air leakage area image; A calculation module, used to obtain the current rotor speed of the air preheater, and determine the air leakage risk value according to the current rotor speed of the air preheater and the direct air leakage characteristic value; The early warning module is used to determine the air leakage level according to the air leakage risk value and to issue an early warning to the air preheater according to the air leakage level.

2. The air preheater air leakage monitoring system according to claim 1, characterized in that: The acquisition module sets the air leakage area image according to the air preheater gap area image, including: Grayscale processing is performed on the gap area image of the air preheater to obtain a grayscale image of the gap area; Obtain a preset grid, and segment the gap region grayscale image according to the preset grid to obtain a plurality of sub-gap region grayscale images; Obtaining an average grayscale value of pixels in the grayscale image of the sub-gap region, and determining similarities of grayscale images of adjacent sub-gap regions according to the average grayscale values ​​of pixels in the grayscale images of adjacent sub-gap regions; The grayscale images of each sub-gap region are merged according to the similarity of the grayscale images of adjacent sub-gap regions to obtain a merged gap region grayscale image; The air leakage area possibility of the merged gap area grayscale image is calculated, and the merged gap area grayscale image whose air leakage area possibility is greater than a first preset threshold is set as the air leakage area image.

3. The air preheater leakage monitoring system according to claim 2, characterized in that: The determining the similarity of the grayscale images of adjacent sub-gap regions according to the average grayscale value of the pixels of the grayscale images of adjacent sub-gap regions comprises: Calculate the difference between the average grayscale values ​​of the pixels of the grayscale images of adjacent sub-gap areas to obtain the grayscale difference; Obtaining a preset grayscale range, and segmenting the pixel points of the grayscale image of the sub-gap area according to the preset grayscale range; Counting the number of segmentation of the grayscale image in the sub-gap region, and calculating the difference in the number of segmentation of the grayscale images in adjacent sub-gap regions; The similarity of the grayscale images of adjacent sub-gap regions is determined according to the grayscale difference of the grayscale images of adjacent sub-gap regions and the difference of the number of segmentations.

4. The air preheater leakage monitoring system according to claim 3, characterized in that: The calculating the possibility of air leakage area of ​​the merged gap area grayscale image includes: Segment the pixel points of the grayscale image of the merged gap area according to a preset grayscale range, and calculate the ratio of the grayscale value of the pixel points in the grayscale image of each merged gap area after segmentation to the preset air leakage grayscale value; The average value of the ratio of the grayscale value of the pixel points of the grayscale image of the merged gap area to the preset air leakage grayscale value is calculated, and the possibility of the air leakage area of ​​the grayscale image of the merged gap area is determined according to the average value of the ratio.

5. The air preheater leakage monitoring system according to claim 4, characterized in that: The detection module performs edge detection on the air leakage area image, and determines the direct air leakage feature value according to the edge detection result of the air leakage area image, including: Perform edge detection on the air leakage area image based on the canny edge detection algorithm to obtain the air leakage edge; Perform triangle fitting on the air leakage edge and calculate the area value of the fitting triangle; Detect the area value of the fitted triangle in real time, and draw the area change curve according to the change of the area value of the fitted triangle; Performing curve fitting on the area change curve, and determining a predicted time when the area value of the fitting triangle reaches a second preset threshold value according to the curve fitting result; The direct air leakage characteristic value is determined according to the predicted time when the area value of the fitted triangle reaches the second preset threshold.

6. The air preheater leakage monitoring system according to claim 5, characterized in that: The calculation module determines the air leakage risk value according to the current rotor speed of the air preheater and the direct air leakage characteristic value, including: Calculate the difference between the current rotor speed of the air preheater and the preset allowable rotor speed, normalize the difference between the current rotor speed of the air preheater and the preset allowable rotor speed, and obtain the carryover air leakage characteristic value; The leakage hazard value of the current air preheater is determined based on the carried air leakage characteristic value and the direct air leakage characteristic value.

7. The air preheater leakage monitoring system according to claim 6, characterized in that: The method of determining the current air leakage risk value of the air preheater according to the carried air leakage characteristic value and the direct air leakage characteristic value includes: The air leakage risk value is determined according to the air leakage risk value calculation formula, and the air leakage risk value calculation formula is specifically: Among them, D is the air leakage hazard value, T is the direct air leakage characteristic value, N is the carried air leakage characteristic value, R is the preset range adjustment value, and exp is the natural exponential function.

8. The air preheater leakage monitoring system according to claim 7, characterized in that: The early warning module determines the air leakage level according to the air leakage risk value, including: Obtain a preset air leakage standard value, and calculate the difference between the current air leakage risk value of the air preheater and the preset air leakage standard value; Determine whether the difference between the current air leakage risk value of the air preheater and the preset air leakage standard value is greater than a third preset threshold value, and if the difference between the current air leakage risk value of the air preheater and the preset air leakage standard value is greater than the third preset threshold value, set the first level of air leakage level; If the difference between the current air leakage risk value of the air preheater and the preset air leakage standard value is less than or equal to the third preset threshold, then determine whether the difference between the current air leakage risk value of the air preheater and the preset air leakage standard value is greater than a fourth preset threshold; If the difference between the current air leakage risk value of the air preheater and the preset air leakage standard value is greater than a fourth preset threshold, the second level is set as the air leakage level; If the difference between the current air leakage risk value of the air preheater and the preset air leakage standard value is less than or equal to the fourth preset threshold value, the third level is set as the air leakage level.

9. The air preheater leakage monitoring system according to claim 8, characterized in that: The early warning module warns the air preheater according to the air leakage level, including: When the air leakage level is the third level, no air leakage warning will be issued for the air preheater; When the air leakage level is the second level, a slight air leakage warning will be issued to the air preheater; When the air leakage level is the first level, a serious air leakage warning is issued for the air preheater.

10. A method for monitoring air leakage in an air preheater, characterized in that: The method comprises: Acquire an air preheater gap area image, and set an air leakage area image according to the air preheater gap area image; Perform edge detection on the air leakage area image, and determine the direct air leakage characteristic value according to the edge detection result of the air leakage area image; Obtain the current rotor speed of the air preheater, and determine the air leakage risk value according to the current rotor speed of the air preheater and the direct air leakage characteristic value; The air leakage level is determined according to the air leakage risk value, and an early warning is issued to the air preheater according to the air leakage level.

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