Method for measuring fineness of pulverized coal

Abstract

The invention relates to the technical field of pulverized coal fineness measurement, in particular to a pulverized coal fineness measurement method. The method comprises the following steps: collecting a pulverized coal distribution image in real time through an automatic detection device arranged in a pulverized coal pipeline, carrying out parallel processing on image data by utilizing a traversal period tracking method, identifying a particle contour and calculating an equivalent diameter, and finally obtaining pulverized coal fineness data through a statistical formula. According to the invention, the problems of complex sampling device, poor real-time performance and high maintenance cost in the traditional method are solved, and rapid and accurate online detection is realized. And the measurement precision and efficiency are further improved by dynamically adjusting the threshold value and equally dividing the interval.

Description

Technical Field

[0001] The present invention relates to the technical field of pulverized coal fineness measurement, and particularly relates to a method for measuring pulverized coal fineness. Background Art

[0002] In order to reduce carbon emissions, reduce air pollution and dependence on fossil fuels, it has become a consensus to vigorously develop renewable energy. However, when renewable energy is connected to the grid for power generation, it does not have the same inertia and damping capabilities as traditional generators, which brings greater disturbances to the stable operation of the power grid. At the same time, as the proportion of renewable energy connected to the grid is increasing day by day, it continuously occupies the share of traditional synchronous generators, and the thermal reserve capacity of the system decreases accordingly, reducing the system's ability to cope with faults and resulting in the deterioration of the power system frequency stability problem. In line with the characteristics of China's resource endowment and the construction of the energy system, coal-fired power is still a conventional power source with relatively mature technology, relatively low cost and relatively comprehensive functions in China. During its transformation to a supporting and regulating power source, the improvement of the flexibility of coal-fired power units will be an important means to ensure the large-scale consumption of new energy and the safe and stable operation of the power grid. With the access of large-scale renewable energy systems and UHV power transmission to the power grid, the demand for deep peak shaving operation, low load operation and rapid load change of thermal power units is increasing. And the stable operation of the boiler is a thorny problem in realizing the above functional requirements. Because the boiler has a complex system and structure, large thermal inertia and hysteresis, both low load and rapid load change are strongly related to combustion stability, and the stable operation of the boiler strongly depends on the coordination of water, coal and air. Among them, the pulverized coal fineness parameter is a key parameter for coal supply during the boiler combustion process, and its accurate measurement is of great significance for the precise control of furnace combustion.

[0003] At present, the measurement methods of pulverized coal fineness mostly adopt manual or automatic sampling, and the pulverized coal fineness is obtained by the screening and weighing method. For this kind of detection method, the sampling method is cumbersome, the pipeline fittings are redundant, and the screening device is complex in configuration, with many parts and is prone to failures, and the real-time performance is poor, making it difficult to meet the real-time requirements of the control loop for pulverized coal fineness detection. Sampling from the pulverized coal and air pipeline, due to the pulverized coal and air scouring and the characteristics of the medium, it is easy to cause failures such as wear of the sampling device and blockage of the pipe fittings, affecting the application effect.

[0004] Currently, the main problems existing in the measurement methods of pulverized coal fineness are that the sampling device has a complex structure, is easy to cause equipment failures such as blockage and wear, and at the same time, due to the large lag in the way of screening and weighing after sampling by the sampling device, it affects the real-time performance of parameter detection and thus makes it difficult to be applied to the control loop. In view of the above problems, how to combine an automatic detection device to quickly, accurately and real-time calculate the pulverized coal fineness data is a technical problem to be solved. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a measurement method for quickly, accurately and real-time calculating pulverized coal fineness data.

[0006] In view of the deficiencies of the prior art, the technical solution adopted by the present invention to solve its technical problems is: a method for measuring the fineness of pulverized coal, comprising the following steps:

[0007] Step 1, image acquisition: Dynamically acquire image data of the pulverized coal distribution in real time in the pulverized coal pipeline through an automatic detection device;

[0008] Step 2, image processing: Transmit the image data to the host computer, and analyze the image data based on the traversal cycle tracing method to identify the contour of the pulverized coal particles;

[0009] Step 3, calculate the equivalent diameter: Determine the contour of the pulverized coal particles through the traversal cycle tracing method, and calculate the equivalent diameter of the particles;

[0010] Step 4, calculate the fineness of pulverized coal: Calculate the fineness data of the pulverized coal according to the statistical result of the equivalent diameter.

[0011] Preferably, the traversal cycle tracing method in step 2 includes:

[0012] a. Take the geometric center of the picture and determine it as the starting point S0;

[0013] b. Determine whether the gray level of the image at point S0 is greater than the set value G0; if the gray level of the image at point S0 is greater than the set value G0, then confirm point S0 as the central solid point; if not, stop the traversal starting from S0;

[0014] c. For the traversal with point S0 as the central solid point, make the following settings:

[0015] The correction ordinal number of the central solid point is j, and the initial value of j = 0; set the counter of the solid point S0 as SR S0j = 1; set the concentric traversal circle ordinal number as i, and the initial value of i = 1;

[0016] d. Take a circular area with an initial radius of R0+(i - 1)Δr, and the circular boundary intersects the horizontal positive and negative axes and the vertical positive and negative axes at points A 0i 、B 0i 、C 0i and D 0i , and sequentially determine whether the gray levels of the images at points A 0i 、B 0i 、C 0i and D 0i are greater than the set value G0? If so, determine the corresponding point as a solid point, and execute SR S0j+i +1, and the initial value of SR S0j+i = 0; SR S0j+i represents the i-th expansion counter with S0 as the solid point as the center;

[0017] e. According to the counter SR S0j+i Based on whether the value of SR is 4, 0, or other cases, perform corresponding operations.

[0018] Preferably, in step e, the operations performed according to the value of the counter SR S0j+i are as follows:

[0019] 1) When SR S0j+i = 4, execute i++, that is, move the circular boundary outward by Δr to obtain the circular boundary of the next circle, and then loop back to step d for recognition and judgment;

[0020] 2) When SR S0j+i = 0, end the traversal;

[0021] 3) Other cases include when SR S0j+i = 1 or SR S0j+i = 2 or SR S0j+i = 3, connect the corresponding solid points among A 0i , B 0i , C 0i and D 0i , take the center S0 1 of the solid points as the new center solid point, and determine whether S0 1 coincides with S0? If so, move along the S0X direction by Δr to determine the new solid point center S0 1' as the corrected S0 1 , where X is an arbitrarily selected solid point in the nearby area; if not, directly determine the S0 1 point as the center solid point; execute j++, and loop back to step c to continue the traversal with the S0 1 point as the center solid point.

[0022] Preferably, the calculation process of the equivalent diameter described in step three includes:

[0023] Determine the center point of the particle contour;

[0024] Select n points on the boundary of the particle contour, and determine n groups of diameters through the connection lines between these points and the center of the particle contour;

[0025] Take the arithmetic mean of the n groups of diameters as the equivalent diameter.

[0026] Preferably, the calculation formula for the pulverized coal fineness data described in step four is:

[0027]

[0028] where, R Ci is the obtained pulverized coal fineness data, Ci is the set pulverized coal fineness value, R m is the obtained diameter of the pulverized coal particle, n is the number of particles with a diameter greater than Ci, and w is the total number of pulverized coal particles.

[0029] Preferably, the automatic detection device includes a detection module and a host computer. The detection module collects dynamic images at a preset period and is connected to the host computer through a transmission cable.

[0030] Preferably, the starting point distribution mode of the traversal cycle tracing method in step two is to evenly divide the image area along the horizontal and vertical directions, and the even division interval is dynamically adjusted according to the test comparison results of the average fineness of pulverized coal.

[0031] The beneficial effects of the present invention are as follows: According to the foregoing content, the present invention proposes a method for detecting the fineness of pulverized coal. In this method, the automatic detection device disposed in the pulverized coal and air pipeline carries the detection module 4 to collect image data of the pulverized coal and air fluid, and transmits it to the host computer 6 in real time through a transmission cable for calculating the fineness of pulverized coal. The calculation method adopts a multi-point parallel calculation method in the horizontal and vertical directions of the area. Each point calculation follows the traversal cycle tracing method. Through position extension, data such as imaging gray scale are identified to complete the particle contour judgment one by one, and then the particle diameter is calculated through the particle contour coordinate data, and then the system calculates the fineness detection of pulverized coal in a certain area. The method proposed by the present invention is convenient for obtaining original data, does not require a complicated sampling pipeline for pulverized coal and air sampling, and reduces mechanical failures. Moreover, the image acquisition data is fast, and the data source can flexibly adjust the sampling period according to the requirements of the control loop. The backend calculation link is based on a high-performance controller, and the multi-point parallel calculation traversal cycle tracing method can quickly complete the calculation of the particle diameter to quickly obtain the fineness data information of pulverized coal. Description of the Drawings

[0032] Figure 1 is a schematic structural diagram of the automatic detection device involved in the present invention;

[0033] Figure 2 is a schematic flow chart of the method of the present invention;

[0034] Figure 3 is a schematic diagram of the pulverized coal distribution involved in the present invention;

[0035] Figure 4 The traversal cycle tracing flow chart of the method of the present invention starting from a certain point.

[0036] Description of the reference numerals: 4, detection module; 6, host computer. Detailed Embodiments

[0037] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention are given for purposes of illustration and description, and are not exhaustive or limit the present invention to the disclosed form. Many modifications and variations are obvious to those of ordinary skill in the art. The embodiments are selected and described to better illustrate the principles and practical applications of the present invention, and enable those of ordinary skill in the art to understand the present invention and design various embodiments with various modifications suitable for specific purposes.

[0038] When coal-fired power units are operating at deep peak shaving, low load, and rapid load change, the stable operation of the boiler faces challenges, and the fineness of pulverized coal (particle diameter distribution) is a key parameter. Traditional methods for measuring the fineness of pulverized coal rely on manual or automatic sampling followed by screening and weighing, and have the following problems:

[0039] The sampling device is complex: the pipeline is redundant, and it is easy to be blocked and worn;

[0040] Poor real-time performance: The detection lags, and it is difficult to meet the requirements of the control loop;

[0041] High maintenance cost: The equipment failure rate is high, affecting continuous operation.

[0042] The method for measuring the fineness of pulverized coal proposed by the present invention is implemented based on the device with the application number 2025204383143, and the utility model name is: An automatic detection device for coal, powder, air, and flue gas pipelines of a coal-fired power unit. This device carries the detection module 4 to collect pictures in the pulverized coal pipeline, and the picture data is sent to the upper computer 6, and the method proposed by the present invention is used for analysis to obtain the fineness data of pulverized coal. An automatic detection device for coal, powder, air, and flue gas pipelines of a coal-fired power unit with the application number 2025204383143 is as Figure 1 shown. The automatic detection device includes a detection module 4 and an upper computer 6. The detection module 4 collects dynamic images at a preset period and is connected to the upper computer 6 through a transmission cable.

[0043] Suppose the pictures collected by the automatic detection device are as follows Figure 3 shown. S0 is the geometric center of the picture, set as the starting point (0, 0), and two horizontal and vertical lines are drawn through the center point S0 to divide the picture area into four parts.

[0044] The method for measuring the fineness of pulverized coal proposed by the present invention is executed according to the Figure 2 process, and specifically includes the following steps:

[0045] Step 1, Image acquisition: The automatic detection device is used to collect dynamic image data of the pulverized coal distribution in the pulverized coal pipeline in real time;

[0046] Step 2, Image processing: The image data is transmitted to the upper computer 6, and the image data is analyzed based on the traversal cycle tracking method to identify the contours of pulverized coal particles;

[0047] Step 3. Calculate the equivalent diameter: Determine the contour of the pulverized coal particles through the above-mentioned traversal cycle tracing method, and calculate the equivalent diameter of the particles.

[0048] Step 4. Calculate the fineness of the pulverized coal: Calculate the fineness data of the pulverized coal according to the statistical result of the equivalent diameter.

[0049] Start looking for the traversal starting point from the geometric center of the picture; perform a periodic traversal starting from a certain point according to the traversal cycle tracing method; record all the real points and their coordinate values of the traversal cycle starting from a certain point, automatically generate a sketch in the coordinate system and calculate its equivalent diameter; collect the equivalent diameters of the particle size intervals in the selected calculation area to obtain the fineness data of the collected sample.

[0050] Specifically, the calculation of the fineness of the pulverized coal in Step 4 is as follows:

[0051] Among them, R Ci is the data of the fineness of the pulverized coal obtained, Ci is the set value of the fineness (diameter) of the pulverized coal, such as 90μm, 150μm, 200μm, etc. R m is the diameter of the obtained pulverized coal particles, n is the number of particles with a diameter greater than Ci, and w is the total number of pulverized coal particles.

[0052] The above-mentioned traversal cycle tracing method starting from a certain point, taking S0 as an example, is executed according to the Figure 4 method shown. Specifically:

[0053] a. Take the geometric center of the picture and determine it as the starting point S0.

[0054] b. Determine whether the gray level of the image at point S0 is greater than the set value G0?

[0055] The value of G0 is determined according to the difference between the pulverized coal imaging and the background color to distinguish the distribution of pulverized coal particles in the imaging data. If the gray level of the image at point S0 is greater than the set value G0, then point S0 is confirmed as the central real point. If not, stop the traversal starting from S0.

[0056] c. For the traversal with point S0 as the central real point, make the following settings:

[0057] The correction ordinal number of the central real point is j, and the initial value of j = 0; set the counter of the real point S0 as SR S0j = 1; set the concentric traversal circle ordinal number as i, and the initial value of i = 1.

[0058] d. Take a circular area with an initial radius of R0+(i - 1)Δr. The circular boundary intersects the horizontal positive and negative axes and the vertical positive and negative axes at points A 0i , B 0i , C0i and D 0i , sequentially judge A 0i , B 0i , C 0i and D 0i whether the gray value of the point image is greater than the set value G0? If so, determine the corresponding point as a solid point and execute SR S0j+i +1, SR S0j+i Initial value = 0.

[0059] SR S0j+i represents the i-th expansion counter centered on the S0 solid point.

[0060] e. According to the value of the counter SR S0j+i perform corresponding operations. The values of SR S0j+i include SR S0j+i = 4, SR S0j+i = 0 and other cases. Other cases include SR S0j+i = 1 or SR S0j+i = 2 or SR S0j+i = 3:

[0061] 1) SR S0j+i = 4, execute i++, that is, move the circular boundary outward by Δr to obtain the next circular boundary, and then loop back to step d for recognition and judgment.

[0062] 2) SR S0j+i = 0, end the traversal.

[0063] 3) Other cases include SR S0j+i = 1 or SR S0j+i = 2 or SR S0j+i = 3, connect the corresponding solid points in A 0i , B 0i , C 0i and D 0i , take the center S0 of the solid points 1 as the new center solid point, and judge whether S0 1 coincides with S0? If so, move Δr along the S0X direction to determine the new solid point center S0 1' as the corrected S0 1 , where X is an arbitrarily selected solid point in the nearby area. If not, directly determine the S0 1 point as the center solid point. Execute j++, and loop back to step c to continue the traversal with the S0 1 point as the center solid point.

[0064] According to the above steps, complete the traversal cycle tracing starting from a certain point. The ones belonging to the counter are SR S0XThe outermost coordinate points of all real point coordinates are connected to form a particle contour, and its equivalent diameter value is calculated. The calculation method is as follows:

[0065] 1. Determine the center point of the particle contour;

[0066] 2. Arbitrarily select n points on the boundary of the particle contour, draw a straight line through the boundary point and the center point of the contour to intersect with the boundary, and obtain n groups of diameter values;

[0067] 3. Obtain the arithmetic mean value of the n groups of diameters as the equivalent diameter value of the particle.

[0068] To enable rapid detection of pulverized coal fineness, a parallel computing method is adopted for multiple starting points of the traversal cycle tracking. The method for determining the starting point is to evenly divide the selected calculation area along the horizontal and vertical directions from the center point. Among them, the equal division interval is initially determined by the method of experimental comparison and corrected according to the actual detection effect.

[0069] The method of experimental comparison is as follows: Take the equal division interval value as the mean value data of the pulverized coal fineness, denoted as f0. Measure the pulverized coal fineness according to the aforementioned method, compare it with other pulverized coal fineness measurement methods to determine its accuracy value. Appropriately enlarge or reduce the equal division interval value according to the test results, and then measure the pulverized coal fineness according to the aforementioned method until its measurement accuracy value meets the set requirements.

[0070] The present invention provides an online measurement method for pulverized coal fineness based on image processing. By using an automatic detection device to collect the pulverized coal distribution image in real time, combining the traversal cycle tracking method and parallel computing technology, the particle contour is quickly identified and the equivalent diameter is calculated, and finally the pulverized coal fineness data is statistically obtained. This method avoids the complexity and lag of traditional sampling devices, significantly improves the detection efficiency and accuracy. The design of dynamically adjusting the threshold and equal division interval further optimizes the adaptability and robustness of the system, and is applicable to the combustion control requirements under the deep peak shaving and rapid load change conditions of coal-fired power units.

Claims

1. A method for measuring coal powder fineness, characterized in that: The following steps are involved: Step 1: Image acquisition: The dynamic image data of the distribution of pulverized coal in the pulverized coal pipeline is collected in real time by an automatic detection device; Step 2: Image processing: the image data is transmitted to a host computer (6), and the image data is analyzed based on a traversal cycle tracking method to identify the contours of coal powder particles; Step 3, calculating the equivalent diameter: determining the contour of the coal powder particles by the traversal cycle tracking method, and calculating the equivalent diameter of the particles; Step 4: Calculate the coal powder fineness: Calculate the coal powder fineness data based on the statistical results of the equivalent diameter.

2. The method for measuring coal powder fineness according to claim 1, characterized in that: The traversal cycle tracking method in step 2 includes: a. Take the geometric center of the image and determine it as the starting point S0; b. Determine whether the grayscale of the image at point S0 is greater than the set value G0; if the grayscale of the image at point S0 is greater than the set value G0, point S0 is confirmed as the center point; if not, stop traversing with S0 as the starting point; c. Traverse with S0 as the center point, and make the following settings: The center point correction number is j, the initial value of j = 0; let the real point S0 counter be SR S0j =1; Set the concentric traversal circle number to i, and the initial value of i = 1; d. Take the initial radius R0+(i-1)Δr to make a circular area. The circular boundary intersects the horizontal positive and negative axes and the vertical positive and negative axes at point A respectively. 0i , B 0i , C 0i and D 0i , judge A in turn 0i , B 0i , C 0i and D 0i Is the grayscale of the point image greater than the set value G0? If so, the corresponding point is determined as a real point and SR is performed. S0j+i +1, SR S0j+i Initial value = 0; SR S0j+i represents the i-th expansion counter with S0 as the center; e. According to the counter SR S0j+i The value of is 4, 0 or other situations, and the corresponding operation is performed.

3. The method for measuring coal powder fineness according to claim 2, characterized in that: In step e, according to the counter SR S0j+i The operations performed on the values ​​are: 1)SR S0j+i =4, execute i++, that is, move the circular boundary outward by Δr to obtain the circular boundary of the next circle, and then loop to step d for identification and judgment; 2)SR S0j+i =0, end the traversal; 3) Other cases including SR S0j+i =1 or SR S0j+i =2 or SR S0j+i =3, A 0i , B 0i , C 0i and D 0i The corresponding real points are connected, and the real point center S0 is taken 1 As the new center point, and judge S0 1 Does it coincide with S0? If so, move Δr along the S0X direction to determine the new real point center S0 1' S0 after correction 1 , X is a real point in the nearby area; if not, S0 will be directly 1 The point is determined as the center point; execute j++, loop to step c and continue to execute S0 1 The traversal of a point with a real point as the center.

4. The method for measuring coal powder fineness according to claim 1, characterized in that: The calculation process of the equivalent diameter in step 3 includes: Determine the center point of the particle outline; Select n points on the boundary of the particle contour, and determine n groups of diameters by connecting the points with the center of the particle contour; The arithmetic mean of the n groups of diameters was taken as the equivalent diameter.

5. The method for measuring coal powder fineness according to claim 1, characterized in that: The calculation formula for the coal powder fineness data in step 4 is: Among them, R Ci is the data of coal powder fineness, Ci is the set value of coal powder fineness, R m To obtain the diameter of the coal powder particles, n is the number of particles with a diameter greater than Ci, and w is the total number of coal powder particles.

6. The method for measuring coal powder fineness according to claim 1, characterized in that: The automatic detection device comprises a detection module (4) and a host computer (6); the detection module (4) collects dynamic images at a preset period and is connected to the host computer (6) via a transmission cable.

7. The method for measuring coal powder fineness according to claim 1, characterized in that: The distribution of the starting points of the traversal period tracking method described in step 2 is to equally divide the image area in the horizontal and vertical directions, and the equal division interval is dynamically adjusted according to the experimental comparison results of the mean value of coal powder fineness.

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