Pipeline accumulated dust thickness online monitoring system and method

Abstract

The invention discloses a pipeline accumulated dust thickness on-line monitoring system and method.The monitoring system comprises a reflecting prism and a flow guide plate which are inserted into a pipeline from a hole in the bottom of the pipeline, and the reflecting prism is used for reflecting the section form of accumulated dust in the pipeline to the outside of the pipeline; then, a pipeline accumulated dust profile image is obtained through an image acquisition unit outside the pipeline, the flow guide plate can avoid flow field interference and influence on dust sedimentation after the reflecting prism is placed in the pipeline, and the measurement precision can be guaranteed; according to the monitoring method, the vertical pixel distance of the accumulated dust and the distance coefficient calibrated according to the horizontal parallel line on the reflecting prism are obtained, and the accumulated dust thickness data are obtained through calculation. The method has the advantage that the thickness of the accumulated dust in the pipeline can be detected on line with high precision.

Description

Technical Field

[0001] The invention relates to dust accumulation thickness detection, and in particular to an online monitoring system and method for dust accumulation thickness in a pipeline. Background Art

[0002] In metal grinding, grain processing, wood processing, tobacco shredding and other dust-related industries, dust removal or smoke exhaust ducts need to be laid to avoid occupational hazards caused by dust, but new problems arise. Excessive dust accumulation in the exhaust system and dust removal system will not only increase wind resistance and affect production energy efficiency, but also pose a major risk of dust explosion. In order to solve the dust safety problem and ensure the low-resistance and efficient operation of the system, according to relevant regulations, the dust accumulation in the duct must be cleaned when the thickness exceeds 1mm. Therefore, it is necessary to monitor the thickness of the dust accumulation in the duct online.

[0003] Existing dust thickness detection methods include laser ranging, ultrasonic ranging, airflow pressure difference monitoring, wall stress (strain) monitoring, etc. Among them, the measurement optical path of the laser ranging method is easily contaminated, the ultrasonic ranging method is easily disturbed by environmental factors, and there are too many factors affecting the airflow pressure difference and wall stress (strain) signals. In addition, these methods do not consider the impact of the detection device or hole position on the flow field and dust settling. In summary, the measurement accuracy of the existing dust thickness detection methods is not high. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a high-precision online monitoring system and method for dust accumulation thickness in pipelines.

[0005] Technical solution: An online monitoring system for dust thickness in a pipeline of the present invention comprises a dust thickness monitoring node, wherein the dust thickness monitoring node comprises a reflecting prism, a guide plate, and a lens module, an image acquisition module and a main control module arranged on the outside of the pipeline; a long strip hole for plugging in the guide plate is opened on the bottom side of the pipeline along the longitudinal section direction, and a square hole for plugging in the reflecting prism is opened on one side of the long strip hole; the guide plate is used to avoid interference with the flow field inside the pipeline; the reflecting prism adopts a right-angle bevel coated prism, and the built-in right-angle surface of the reflecting prism coincides with the longitudinal section of the pipeline and fits with the guide plate; at least two horizontal parallel lines are etched in the horizontal direction on the upper edge of the built-in right-angle surface, and the horizontal parallel lines are located above the dust thickness detection working area; the lens module and the image acquisition module face the external right-angle surface of the reflecting prism; the reflecting prism reflects the dust profile image in the pipeline to the outside of the pipeline, and projects it to the image acquisition module through the lens module; the main control module obtains the dust thickness data according to the collected pipeline dust profile image.

[0006] Furthermore, the lens module includes a focus adjustment lens barrel and a lens installed at the front end of the focus adjustment lens barrel.

[0007] Furthermore, the image acquisition module adopts a grayscale image sensor.

[0008] Furthermore, the dust thickness monitoring node also includes a program-controlled fill light module, the light of the program-controlled fill light module enters the pipeline through a reflective prism, and outputs light of required brightness under the control of the main control module to ensure imaging contrast.

[0009] Furthermore, the programmable fill light module includes two fill light lamps respectively arranged on both sides of the image acquisition module, and the two fill light lamps work in turn to obtain the cross-sectional images of the dust accumulation in the pipeline under different illumination angles.

[0010] Furthermore, the reflecting prism and the guide plate are glued together into a whole.

[0011] Furthermore, the dust thickness monitoring node also includes a power supply communication module and an address setting module; the pipeline dust thickness online monitoring system includes a main controller, a hub and multiple dust thickness monitoring nodes, wherein the multiple dust thickness monitoring nodes are arranged at different positions of the same pipeline or on different pipelines; the address setting module is used to set the communication address of the monitoring node, so as to facilitate the time-sharing collaborative work of multiple dust thickness monitoring nodes of the monitoring system; the power supply communication module is connected to the main controller via the hub, and is responsible for powering the monitoring node, receiving communication instructions from the main controller, and outputting image data and dust thickness data.

[0012] Furthermore, the dust thickness monitoring node also includes a shell, which is fixed to the bottom side of the pipeline and covers the reflective prism and the guide plate, and each module is installed in the shell.

[0013] The present invention provides an online monitoring method for the thickness of dust accumulation in a pipeline. The method comprises the following steps: obtaining a cross-sectional image of dust accumulation in a pipeline through the above-mentioned online monitoring system for the thickness of dust accumulation in a pipeline, preprocessing the cross-sectional image of dust accumulation in a pipeline, and then searching from both sides of the thickness direction of dust accumulation in a pipeline through the Canny algorithm to extract the bottom edge of the cross-sectional image of dust accumulation in a pipeline and the top edge of the cross-sectional image of dust accumulation in a pipeline, and calculating the vertical distance of each pixel on the top and bottom edges of the dust accumulation; searching along the bottom edge direction of the dust accumulation image through the Canny algorithm to extract the horizontal parallel lines on the built-in right-angle surface of the reflecting prism, and calibrating the distance coefficient according to the actual spatial distance and pixel distance between the horizontal parallel lines; and further obtaining dust thickness data according to the vertical pixel distance and the distance coefficient of the top and bottom edges of the dust accumulation.

[0014] Furthermore, the dust accumulation thickness data is obtained by calculating the dust accumulation thickness in the width direction of the reflecting prism and taking an average value. The dust accumulation thickness in the width direction of the reflecting prism is all involved in the calculation, which has an average effect and can overcome the limitation of single-point detection.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0016] The core principle of the present invention is to reflect the cross-sectional shape of dust accumulated in the pipeline to the outside of the pipeline through the internal light path of the reflecting prism, and then obtain the cross-sectional image of the dust accumulated in the pipeline through the image acquisition unit outside the pipeline, and then calculate the thickness of the dust accumulated in the pipeline through the image analysis method, which has the following advantages.

[0017] (1) The built-in guide plate and reflective prism are passive devices with a very high dust explosion safety factor. The guide plate separates the flow field, which can avoid the flow field interference and the influence on dust deposition after the reflective prism is placed in the pipeline, which helps to ensure the measurement accuracy;

[0018] (2) The cross-sectional image of the dust accumulation in the pipeline is reflected to the outside of the pipeline through a reflecting prism, thus avoiding light path pollution. The cross-sectional image of the dust accumulation can be obtained intuitively and the dust accumulation thickness can be obtained through image processing, thus realizing online monitoring;

[0019] (3) Not easily disturbed by various factors, high measurement accuracy;

[0020] In summary, the present invention has the advantage of being able to detect the thickness of dust accumulation in the pipeline online with high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a multi-node architecture diagram of the pipeline dust accumulation thickness online monitoring system in an embodiment of the present invention.

[0022] Figure 2 Schematic diagram of the module structure of the dust thickness monitoring node in an embodiment of the present invention;

[0023] Figure 3 and Figure 4 is a schematic diagram of the specific structure of the dust thickness monitoring node in an embodiment of the present invention, wherein Figure 3 is the main view, Figure 4 It is a side view. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] Attached Figures 1 to 4 The reference numerals in the figures are as follows:

[0026] 1. Reflecting prism; 2. Guide plate; 3. Pipe; 4, 14, first fixing screw; 5. Shell; 6. Lens; 7. Focus adjustment lens barrel; 8. Image acquisition module; 9, 15. Fill light; 10. Power supply and communication module; 11. Main control module; 12, 13, second fixing screws; 16, 17, third fixing screws.

[0027] Example 1

[0028] like Figure 1As shown, Example 1 provides an online monitoring system for dust accumulation thickness in a pipeline, which adopts a master-slave communication architecture, including a main controller, a hub and multiple dust accumulation thickness monitoring nodes, wherein the multiple dust accumulation thickness monitoring nodes are arranged at different positions of the same pipeline or on different pipelines, and the multiple dust accumulation thickness monitoring nodes are connected to the hub via cables, and the hub is connected to the main controller via cables. In addition to the communication function, the cable is also responsible for providing power to each dust accumulation thickness monitoring node.

[0029] like Figures 2 to 4 As shown, the dust thickness monitoring node includes a reflective prism 1, a guide plate 2, a shell 5, and a lens module, an image acquisition module 8, a power supply and communication module 10, a main control module 11, a programmable fill light module and an address setting module arranged on the outside of the pipe 3.

[0030] Both ends of the pipe 3 are provided with flanges, the specifications of which are the same as those of standard pipes of the same size, so as to facilitate connection to smoke exhaust or dust removal pipes.

[0031] The bottom side of the pipe 3 is provided with a long strip hole and a square hole along the longitudinal section direction. The long strip hole is used to plug the guide plate 2, and the square hole is used to plug the reflective prism 1. The reflective prism 1 and the guide plate 2 are inserted into the pipe 3 through the opening at the bottom of the pipe 3. The guide plate 2 is used to separate the flow field to avoid interference with the flow field after the detection device is placed in the pipe 3.

[0032] The reflective prism 1 is a right-angled bevel coated prism. The internal right-angle surface of the reflective prism 1 coincides with the longitudinal section of the pipe 3 and fits with the guide plate 2. The reflective prism 1 and the guide plate 2 are glued together as a whole. Two horizontal parallel lines are etched in the horizontal direction on the internal right-angle surface, and the horizontal parallel lines are located above the dust thickness detection working area. The external right-angle surface of the reflective prism 1 coincides with the section of the outer surface of the pipe 3.

[0033] The lens module and the image acquisition module 8 face the external right-angle surface of the reflective prism 1, and the three are arranged in a colinear manner, wherein the lens module includes a focus adjustment barrel 7 and a lens 6 installed at the front end of the focus adjustment barrel 7, and the focus is locked after the focus is adjusted. The cross-sectional image of the dust accumulation in the pipeline is reflected to the outside of the pipeline 3 by the reflective prism 1, and is projected to the image acquisition module 8 through the lens module. The image acquisition module 8 uses a grayscale image sensor to convert the dust accumulation image into image data that can be processed by the main control module 11.

[0034] The main control module 11 obtains dust thickness data based on the collected pipeline dust profile image. The data processing process of the main control module 11 is described in detail in the following pipeline dust thickness online monitoring method.

[0035] The address setting module is used to set the communication address of this monitoring node, so as to facilitate the time-sharing and collaborative work of multiple dust thickness monitoring nodes of the monitoring system. The program-controlled fill light module is used to overcome the problem of insufficient imaging contrast caused by insufficient lighting in the pipeline. The light of the program-controlled fill light module enters the pipeline 3 through the reflecting prism 1, and outputs the required brightness of light under the control of the main control module 11, so that the image acquisition module 8 can obtain the best imaging effect. In this embodiment, the program-controlled fill light module includes a fill light 9 and a fill light 15. The two fill lights are respectively arranged on both sides of the image acquisition module 8, and the two fill lights work in turn to obtain the profile image of the dust accumulation in the pipeline under different illumination angles, thereby improving the reliability of the dust thickness monitoring results. The power supply communication module 10 is connected to the main controller via a hub, and is responsible for powering the monitoring node, receiving communication instructions from the main controller, and outputting image data and dust thickness data.

[0036] The housing 5 is fixed to the bottom side of the pipe 3 by first fixing screws 4 and 14 and covers the reflective prism 1 and the guide plate 2. Each module is installed in the housing 5, wherein the main control module 11 is fixed in the housing 5 by second fixing screws 12 and 13. The bottom of the guide plate 2 is fixed to the housing 5 by third fixing screws 16 and 17.

[0037] The specific hardware structure of this embodiment is as follows:

[0038] Main controller: embedded industrial computer, communication adopts Ethernet + HUB + PoE power supply;

[0039] Image naming rules: station number + system time;

[0040] Main control module 11: 4-core Cortex-A53 CPU, 2GB RAM, integrated RJ45 network port, Ethernet protocol, integrated OpenCV library, and supports Python programming;

[0041] Image acquisition module 8 (CCD): OpenCV grayscale camera, image resolution 640*480, actual field of view height of about 15mm, dust thickness monitoring resolution of about 0.03mm, meeting the requirements of 1mm pipeline dust thickness monitoring;

[0042] Lens module: Yutong F1.0 adjustable lens, focal length 2.8mm;

[0043] Reflecting prism 1: equilateral right-angle prism, right-angle side length 5mm, bevel coated with reflective film, built-in working surface coated with zirconium oxide enhanced coating; the right-angle side length of 5mm is much larger than the upper limit of the dust accumulation in the pipeline that must be cleaned when the thickness exceeds 1mm (so there is no need to consider the problem of the prism being covered with dust as a whole);

[0044] Guide plate 2: The dimensions of the guide plate placed in the pipe are 300 mm wide, 50 mm high and 1 mm thick;

[0045] Fill light: LED, 560nm green light ball head, emitting angle 110°.

[0046] Example 2

[0047] Embodiment 2 provides a method for online monitoring of dust accumulation thickness in a pipeline, which is introduced below in conjunction with the online monitoring system for dust accumulation thickness in a pipeline given in Embodiment 1.

[0048] 1. Workflow of the main control module

[0049] After the image acquisition module 8 obtains the cross-sectional image of the duct dust accumulation, the main control module 11 is responsible for analyzing and processing the obtained cross-sectional image of the duct dust accumulation, including extracting the bottom and top edges of the dust accumulation image and the horizontal parallel lines on the built-in working surface of the prism. The specific steps are as follows:

[0050] (1) Data preprocessing: This step is a prior art.

[0051] Image extraction: Extract the effective pixel area according to the physical structure of the system to avoid interference from factors such as prism edges;

[0052] Image smoothing: Use a low-pass filter to reduce noise in the effective pixel area;

[0053] Gradient calculation: Calculate the horizontal and vertical gradients of the filtered image to obtain the gradient amplitude and direction of each pixel in the effective pixel area;

[0054] Non-maximum suppression: Perform non-maximum suppression on the gradient amplitude, remove redundant edges, and refine the edges to a single pixel; traverse all pixel points in the image and retain the point with the largest local gradient;

[0055] Double threshold processing: set the upper threshold and the lower threshold, mark the pixels whose gradient amplitude is greater than the upper threshold as strong edge pixels, mark the pixels whose gradient amplitude is less than the upper threshold and greater than the lower threshold as weak edge pixels, and mark the remaining pixels as 0;

[0056] Edge connection: Track and connect weak edge pixels, check the neighborhood of weak edge pixels, and if there is a strong edge pixel in the neighborhood, connect the weak edge pixel to the strong edge pixel to form a complete edge;

[0057] (2) Using the Canny algorithm, search from both sides of the pipeline dust thickness direction to extract the bottom edge of the pipeline dust profile image (i.e., the upper edge of the pipeline contour) and the top edge of the pipeline dust profile image, and calculate the vertical distance of each pixel on the top and bottom edges of the dust;

[0058] (3) Using the Canny algorithm, a search is performed along the bottom edge direction of the pipeline dust accumulation image to extract the horizontal parallel lines on the built-in right-angle surface of the reflective prism 1, and the distance coefficient is calibrated according to the actual spatial distance and pixel distance between the horizontal parallel lines;

[0059] (4) According to the vertical pixel distance obtained in step (2) and the distance calibration coefficient obtained in step (3), the average dust thickness data is obtained. The dust thickness data of this embodiment is to calculate the dust thickness in the width direction of the reflective prism 1 and take the average value.

[0060] 2. Workflow of dust thickness monitoring node

[0061] (1) According to the configuration of the address setting module, the communication address of the monitoring node is set and the handshake communication of the main controller is responded;

[0062] (2) According to the pre-stored illumination control parameter 1, the fill light 9 is turned on to obtain the image of dust accumulation in the pipeline, and the image contrast is calculated according to the image grayscale. If the image contrast is less than 0.6, the illumination control parameter 1 is adjusted until the image contrast is greater than or equal to 0.6, and the pre-stored illumination control parameter 1 is updated and stored;

[0063] (3) According to the pre-stored illumination control parameter 2, the fill light 15 is turned on to obtain the dust accumulation image of the pipeline, and the image contrast is calculated according to the image grayscale. If the image contrast is less than 0.6, the illumination control parameter 2 is adjusted until the image contrast is greater than or equal to 0.6, and the pre-stored illumination control parameter 2 is updated and stored;

[0064] (4) Turn on the fill light 9, obtain the current image of dust accumulation in the pipeline, then turn off the fill light, and calculate the average thickness of the dust accumulation according to the above steps;

[0065] (5) Turn on the fill light 15, obtain the current image of dust accumulation in the pipeline, then turn off the fill light, and calculate the average thickness of the dust accumulation according to the above steps;

[0066] (6) Calculate the relative error of the results of step (4) and step (5); if the relative error is less than or equal to 5%, save the image corresponding to the result with larger dust thickness and the dust thickness calculation result; if the relative error is greater than 5%, save the image of step (4) and step (5), the dust thickness calculation result and a warning message;

[0067] (7) Waiting for the main controller to read the communication instruction of the monitoring node;

[0068] (8) Encapsulating the image, result and warning information saved in step (6) into a data frame and uploading it;

[0069] (9) Repeat steps (4) to (6).

[0070] 3. Workflow of the main controller

[0071] (1) Search the set address space, enumerate all dust thickness monitoring nodes, generate a node address list and a folder named after each node address; set the inspection cycle;

[0072] (2) Read the node address list, build and read the communication command frame;

[0073] (3) Waiting for the node to respond and receiving the node's uploaded data frame;

[0074] (4) Analyze and reconstruct the data frame uploaded by the node, display the calculation result of the dust thickness of the node and the warning information (if any); save the reconstructed image in the corresponding folder;

[0075] (5) Repeat steps (2) to (4) until all nodes are read;

[0076] (6) Repeat steps (2) to (5) according to the inspection cycle set in step (1).

Claims

1. An online monitoring system for dust accumulation thickness in pipelines, characterized in that: The dust accumulation thickness monitoring node comprises a reflection prism (1), a guide plate (2), and a lens module, an image acquisition module (8), and a main control module (11) arranged outside a pipe (3); a long strip hole for plugging the guide plate (2) is provided on the bottom side of the pipe (3) along the longitudinal section direction, and a square hole for plugging the reflection prism (1) is provided on one side of the long strip hole; the guide plate (2) is used to avoid interference with the internal flow field of the pipe (3); the reflection prism (1) adopts a right-angle bevel coated prism, and the reflection prism (1) The built-in right-angle surface coincides with the longitudinal section of the pipeline (3) and fits with the guide plate (2); at least two horizontal parallel lines are etched in the horizontal direction on the built-in right-angle surface, and the horizontal parallel lines are located above the dust thickness detection working area; the lens module and the image acquisition module (8) face the external right-angle surface of the reflection prism (1); the reflection prism (1) reflects the dust accumulation cross-section image in the pipeline (3) to the outside of the pipeline (3), and projects it to the image acquisition module (8) through the lens module; the main control module (11) obtains dust accumulation thickness data according to the collected pipeline dust accumulation cross-section image.

2. The on-line monitoring system for dust accumulation thickness in pipelines according to claim 1 is characterized in that: The lens module comprises a focus adjustment lens barrel (7) and a lens (6) mounted on the front end of the focus adjustment lens barrel (7).

3. The on-line monitoring system for dust accumulation thickness in pipelines according to claim 1 is characterized in that: The image acquisition module (8) adopts a grayscale image sensor.

4. The on-line monitoring system for dust accumulation thickness in pipelines according to claim 1 is characterized in that: The dust accumulation thickness monitoring node also includes a program-controlled fill light module, the light of which enters the pipeline (3) through the reflection prism (1) and outputs light of required brightness under the control of the main control module (11) to ensure imaging contrast.

5. The on-line monitoring system for dust accumulation thickness in pipelines according to claim 4 is characterized in that: The program-controlled fill light module comprises two fill light lamps respectively arranged on both sides of the image acquisition module (8); the two fill light lamps work in turn to obtain pipeline dust accumulation profile images under different illumination angles.

6. The on-line monitoring system for dust accumulation thickness in pipelines according to claim 1 is characterized in that: The reflecting prism (1) and the guide plate (2) are glued together to form a whole.

7. The system for online monitoring of dust accumulation thickness in pipelines according to any one of claims 1 to 6, characterized in that: The dust thickness monitoring node also includes a power supply communication module (10) and an address setting module; the pipeline dust thickness online monitoring system includes a main controller, a hub and multiple dust thickness monitoring nodes, wherein the multiple dust thickness monitoring nodes are arranged at different positions of the same pipeline or on different pipelines; the address setting module is used to set the communication address of the monitoring node, so as to facilitate the time-sharing and coordinated work of the multiple dust thickness monitoring nodes of the monitoring system; the power supply communication module (10) is connected to the main controller via the hub, and is responsible for powering the monitoring node, receiving communication instructions from the main controller, and outputting image data and dust thickness data.

8. The on-line monitoring system for dust accumulation thickness in pipelines according to claim 7 is characterized in that: The dust accumulation thickness monitoring node further comprises a shell (5), which is fixed to the bottom side of the pipeline (3) and covers the reflective prism (1) and the guide plate (2), and each module is installed in the shell (5).

9. A method for online monitoring of dust accumulation thickness in a pipeline, characterized in that: A duct dust profile image is obtained by using an online monitoring system for duct dust thickness according to any one of claims 1 to 8, the duct dust profile image is preprocessed, and then a search is performed from both sides of the duct dust thickness direction by using a Canny algorithm to extract the bottom edge of the duct dust profile image and the top edge of the duct dust profile image, and the vertical distance of each pixel on the top and bottom edges of the dust is calculated; a search is performed along the bottom edge direction of the duct dust image by using a Canny algorithm to extract the horizontal parallel lines on the built-in right-angle surface of the reflective prism (1), and the distance coefficient is calibrated according to the actual spatial distance and pixel distance between the horizontal parallel lines; and dust thickness data is further obtained according to the vertical pixel distance and distance coefficient of the top and bottom edges of the dust.

10. The method for online monitoring of dust accumulation thickness in a pipeline according to claim 9, characterized in that: The dust accumulation thickness data is obtained by calculating the dust accumulation thickness in the width direction of the reflecting prism (1) and taking the average value.

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