A method for evaluating the dust cleaning effect of a rotary air preheater corrugated plate

Abstract

The present application relates to a kind of rotary air preheater corrugated plate ash removal effect evaluation method, it is related to the field of cleaning, including the following steps, the corrugated plate on the inner blade of unused air preheater is scanned by ultrasonic probe to obtain ultrasonic image as original image and record;Air preheater is cleaned after use by high-pressure water gun, and is cleaned by adopting acoustic wave soot blower cooperation;Corrugated plate is scanned by ultrasonic probe to obtain ultrasonic image as cleaning image and record;Cleaning image is compared with original image, according to the size of the bright spot in cleaning image, number intuitive judgment ash removal effect, and calculate dust removal rate by the light and shade of bright spot, the present application has the advantages that more accurate, non-destructive evaluation method of degree of fouling cleaning can be provided, to realize the accurate judgment of the inside cleaning condition of corrugated plate.

Description

Technical Field

[0001] This invention relates to the field of cleaning technology, and in particular to a method for evaluating the dust removal effect of corrugated plates in rotary air preheaters. Background Technology

[0002] The rotary air preheater consists of corrugated plate heat transfer elements, which are arranged in an element box and then placed inside the preheater. Because the corrugated plate channels are narrow and the gas flowing through the air preheater contains dust, the corrugated plates easily accumulate dust over time, affecting the performance and efficiency of the air preheater, resulting in reduced capacity and increased costs. Therefore, it is necessary to regularly clean the corrugated plates with a high-pressure water gun to remove the accumulated dust and restore their normal function.

[0003] The existing method for evaluating the cleaning effect of high-pressure water guns mainly involves power plant staff observing the light transmittance of the corrugated plates and comparing the light transmittance of the gaps between the corrugated plates before and after cleaning to judge the cleaning effect. However, this method not only requires a lot of manpower and experience, but also has a large margin of error in human judgment. It can only be observed qualitatively and cannot accurately and quantitatively evaluate the cleaning effect.

[0004] Therefore, to address the above shortcomings, a method for evaluating the dust removal effect of the corrugated plate in a rotary air preheater is needed. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] The technical problem to be solved by this invention is that the cleaning effect of corrugated plates cannot be quantitatively evaluated after cleaning.

[0007] (II) Technical Solution

[0008] To address the aforementioned technical problems, this invention provides a method for evaluating the dust removal effect of corrugated plates in a rotary air preheater, comprising the following steps:

[0009] Ⅰ. Use an ultrasonic probe to scan the corrugated plates on the blades of the unused air preheater to obtain ultrasonic images as raw images and record them;

[0010] II. After use, the air preheater should be cleaned with a high-pressure water gun and an ultrasonic soot blower.

[0011] III. Use an ultrasonic probe to scan the corrugated plate to obtain ultrasonic images as cleaning images and record them;

[0012] IV. Compare the cleaned image with the original image. Based on the size and number of bright spots in the cleaned image, the dust removal effect can be judged intuitively. The dust removal rate can be calculated by the brightness of the bright spots.

[0013] As a further explanation of the present invention, preferably, each blade is numbered and recorded before scanning the original image, and the ultrasonic probe scans the corrugated plate on the blade according to the order of the number.

[0014] As a further explanation of the present invention, preferably, both the ultrasonic probe and the acoustic soot blower are arranged on the compensator, and the ultrasonic probe and the acoustic soot blower move horizontally on the compensator.

[0015] As a further explanation of the present invention, preferably, the ultrasonic probe operates at a different frequency than the acoustic soot blower and the ultrasonic probe has a shorter wavelength.

[0016] As a further explanation of the present invention, preferably, the frequency range of the ultrasonic probe is 5 to 10 MHz, and the frequency range of the acoustic soot blower is 70 to 200 Hz.

[0017] As a further explanation of the present invention, preferably, after the high-pressure water gun has finished cleaning, the air preheater is first started to make the blades rotate, and then the sonic soot blower is turned on to clean the corrugated plate on the blades to remove water stains and dust with water stains adhering to it.

[0018] As a further explanation of the present invention, preferably, when the cleaned image is compared with the original image, the appearance of a wide strip-shaped bright spot image or a block-shaped bright spot image indicates that the area is not cleaned properly and needs to be cleaned specifically with a high-pressure water gun. If the image difference area is less than 2%, it indicates that the area is clean.

[0019] As a further explanation of the present invention, preferably, the presence of scattered bright spots or thin stripe-like bright spots after comparing the clean image with the original image indicates that the surface of the corrugated plate has pits or scratches, and the air preheater needs to be removed and the corrugated plate replaced.

[0020] As a further explanation of the present invention, preferably, the formula for calculating the dust accumulation thickness h and the brightness B of the bright spot is as follows:

[0021]

[0022] in,

[0023] α is the slope of the maximum and minimum dust accumulation thickness;

[0024] B1 represents the brightness of the corrugated plate;

[0025] β is the decay exponent, which is close to 1.

[0026] As a further explanation of the present invention, preferably, the formula for calculating the dust removal rate μ is:

[0027]

[0028] in,

[0029] H represents the thickness of the accumulated dust before cleaning.

[0030] (III) Beneficial Effects

[0031] The above-described technical solution of the present invention has the following advantages:

[0032] This invention introduces ultrasonic imaging technology, which utilizes the fact that the propagation of ultrasonic waves in different media is related to the density of the medium and the speed of sound. These two factors together determine the acoustic impedance of the medium. Therefore, sound waves passing through the cleaned corrugated plate and residual dust will produce different reflected waves. By calculating the dust thickness and dust removal rate, the cleaning effect of the corrugated plate can be quantitatively analyzed. Attached Figure Description

[0033] Figure 1 This is a simplified structural diagram of the present invention;

[0034] Figure 2 This is the logic diagram of the present invention.

[0035] In the diagram: 1. Air preheater; 11. Shaft; 12. Blade; 13. Corrugated plate; 2. Compensator; 21. Slide rail; 22. Ultrasonic probe; 23. Acoustic soot blower. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] A method for evaluating the dust removal effect of corrugated plates in rotary air preheaters, combined with Figure 1 , Figure 2This evaluation method employs an ultrasonic compensator 2. The portion of the compensator 2 extending into the air preheater 1 is fixedly connected to a horizontal slide rail 21. An ultrasonic probe 22 and an acoustic soot blower 23 are fixed together and slidably connected to the slide rail 21, allowing the ultrasonic probe 22 and the acoustic soot blower 23 to move horizontally on the compensator 2. This enables scanning of the corrugated plates 13 on the blades 12 along their length within the air preheater 1. The ultrasonic probe 22 has a frequency range of 5–10 MHz, while the acoustic soot blower 23 has a frequency range of 70–200 Hz. The ultrasonic probe 22 and the acoustic soot blower 23 operate at different frequencies, and the ultrasonic probe 22 has a shorter wavelength. Through this configuration, the ultrasonic probe 22 and the acoustic soot blower 23 can perform ultrasonic imaging and acoustic cleaning respectively, without mutual interference. This improves detection accuracy while removing water stains adhering to the walls, significantly enhancing the cleaning effect. At the same time, when it is determined that the cleaning effect of a certain corrugated plate 13 is low, the sonic soot blower 23 can be used to clean that area in a special way, so as to ensure that the entire air preheater 1 is thoroughly cleaned and the service life of the air preheater 1 is improved in the next stage.

[0038] The specific evaluation method includes the following steps:

[0039] I. Number the unused blades 12 inside the air preheater 1 and mark them in the system. Then, use an ultrasonic probe 22 to scan the ultrasonic image of the corrugated plate 13 inside each blade 12 as the original image and record it.

[0040] II. When the air preheater 1 needs to be cleaned after use, it is cleaned with a traditional high-pressure water gun. Then, the high-pressure water gun is turned off, and the compensator 2 is inserted into the sonic blower 23 to assist in the cleaning, so as to perform a secondary cleaning of the water stains and dust stuck to the wall.

[0041] III. An ultrasonic image of the corrugated plate 13 is scanned using an ultrasonic probe 23 and recorded as a cleaning image. Then, the air preheater 1 is activated, causing the shaft 11 to slowly rotate the blades 12 so that the corrugated plate 13 to be tested is directly below the ultrasonic probe 22. The corrugated plates 13 on the blades 12 are scanned in numerical order for easy statistical analysis.

[0042] IV. Compare the cleaned image with the original image. The size and number of bright spots in the cleaned image visually indicate the cleaning effect. Wide stripes or blocks of bright spots appearing after comparing the cleaned and original images indicate that the area is not cleaned properly and requires targeted cleaning with a high-pressure water gun. If the difference in the image area is less than 2%, it indicates that the area is clean. The formulas for calculating the dust accumulation thickness h and the bright spot brightness B are:

[0043]

[0044] in,

[0045] α is the slope of the maximum and minimum ash accumulation thickness. This is a constant set based on experience. This constant varies depending on the sulfur content in the pulverized coal and the flue gas temperature, among other factors.

[0046] B1 represents the brightness of the corrugated plate;

[0047] β is the decay exponent, which is close to 1, and preferably 1.

[0048] The brightness of an ultrasonic image is usually related to the intensity of the reflected signal, which is affected by the thickness of the object. Therefore, the thickness of the dust accumulation can be easily judged by the brightness of the ultrasonic image. The shape of the dust accumulation is not a regular structure, but it generally follows the characteristic of being thicker in the middle and thinner around the edges. Therefore, this invention introduces an empirical constant, selecting the value of α according to a parameter table, and combining this with the measurement of the brightness B of the bright spot to estimate the thickness of the dust accumulation. This allows for targeted cleaning using a high-pressure water gun or an ultrasonic soot blower 23. Analysis of the dust accumulation thickness shows that when the thickness is small, the ultrasonic soot blower 23 can be used directly to clean the remaining dust, reducing water consumption.

[0049] Additionally, the dust removal rate can be calculated by observing the brightness of the bright spots. The formula for calculating the dust removal rate μ is:

[0050]

[0051] in,

[0052] H represents the thickness of the accumulated dust before cleaning.

[0053] By calculating the dust removal rate, we can quantitatively determine whether the current dust removal method is efficient. If the dust removal rate is low, we need to change the current dust removal method by increasing the water gun pressure, changing the water gun cleaning angle, changing the rotation speed of the rotating shaft 11, etc., and then select the dust removal method with the highest dust removal rate to improve the dust removal efficiency.

[0054] Furthermore, if scattered bright spots or thin stripe-like bright spots appear after comparing the cleaned image with the original image, it indicates that pits or scratches have appeared on the surface of the corrugated plate 13, requiring the air preheater 1 to be disassembled and the corrugated plate 13 replaced. The combination of the ultrasonic probe 22 and the acoustic soot blower 23 used in this invention not only allows for the evaluation of the cleaning effect of the air preheater 1 but also improves the cleaning effect. Furthermore, the lower wavelength ultrasonic probe 22 can be used to identify defects on the surface of the corrugated plate 13, achieving the effect of inspection without disassembling the air preheater 1, thus achieving multiple benefits.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the cleaning effect of a corrugated plate in a rotary air preheater, characterized in that: It comprises the following steps, I. Numbering and recording each leaf (12) before scanning the original image, and the ultrasonic probe scans the corrugated plate (13) on the leaf (12) in order according to the size of the number, and the ultrasonic image of the corrugated plate (13) on the unused air preheater (1) is scanned by the ultrasonic probe (22) as the original image and recorded; wherein the ultrasonic probe (22) and the acoustic blower (23) are arranged on the compensator (2), and the ultrasonic probe (22) and the acoustic blower (23) move horizontally on the compensator (2); the ultrasonic probe (22) and the acoustic blower (23) have different working frequencies, and the ultrasonic probe (22) has a short wavelength; the frequency range of the ultrasonic probe (22) is 5-10 MHz, and the frequency range of the acoustic blower (23) is 70-200 Hz; II. After the air preheater (1) is used, it is cleaned by high-pressure water gun, and the acoustic blower (23) is used for cleaning; III. The ultrasonic probe (22) is used to scan the ultrasonic image of the corrugated plate (13) as the cleaning image and record; IV. The cleaning image is compared with the original image, the dust removal effect is judged intuitively according to the size and number of bright spots in the cleaning image, and the dust removal rate is calculated through the brightness of the bright spots; wherein the dust thickness The calculation formula of the bright spot brightness is: Wherein, is the slope of the maximum and minimum of the thickness of the deposit; Brightness of the corrugated board; is the decay exponent.

2. The method for evaluating the cleaning effect of the corrugated plate of the rotary air preheater according to claim 1, characterized in that: After the high-pressure water gun cleaning is completed, the air preheater (1) is started to make the leaf (12) rotate, and then the acoustic blower (23) is started to clean the corrugated plate (13) on the leaf (12) to remove water stains and dust with water stains.

3. The method for evaluating the cleaning effect of the corrugated plate of the rotary air preheater according to claim 1, characterized in that: After comparing the cleaning image with the original image, if a wide strip-shaped bright spot image or a block-shaped bright spot image appears, it means that the place has not been cleaned thoroughly, and the high-pressure water gun needs to be used for targeted cleaning. If the image difference area is less than 2%, it means that the cleaning is clean.

4. The method for evaluating the cleaning effect of the corrugated plate of the rotary air preheater according to claim 3, characterized in that: After comparing the cleaning image with the original image, if a scattered point bright spot or a fine strip bright spot appears, it means that the surface of the corrugated plate has appeared concave or scratch, and the air preheater (1) needs to be disassembled to replace the corrugated plate (13).

5. The method for evaluating the cleaning effect of the corrugated sheet of the rotary air preheater according to claim 4, characterized in that: Dust removal rate The calculation formula is: Wherein, Pre-cleaning soot thickness.

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