Method and device for detecting a sludge interface in a sedimentation tank

Abstract

The application is suitable for the technical field of ultrasonic detection, and provides a detection method and device for a sludge interface of a sedimentation tank, which are used for improving the detection precision of the sludge interface. The method comprises the following steps: obtaining a reflected echo signal data set of a multi-frequency ultrasonic signal after the multi-frequency ultrasonic signal is incident to the sedimentation tank; determining echo features corresponding to each medium layer based on an echo feature fusion matrix constructed based on the echo signal data set, each medium layer being a clear water layer, a transition layer and a sludge layer distributed along the longitudinal direction of the sedimentation tank; inputting real-time temperature values and real-time sludge concentration values of each medium layer into a preset propagation speed correction model to obtain actual propagation speeds of each medium layer; calculating a first propagation path distance of the clear water layer and a second propagation path distance of the transition layer based on the actual propagation speeds of each medium layer, and determining the underwater depth of the sludge interface in the sedimentation tank according to the sum of the first propagation path distance and the second propagation path distance.

Description

Technical Field

[0001] This application belongs to the field of ultrasonic testing technology, and in particular relates to a method and apparatus for detecting the interface of sludge in sedimentation tanks. Background Technology

[0002] Sedimentation tanks are key solid-liquid separation devices in wastewater treatment, tap water purification, and industrial water treatment processes. They rely on gravity settling to separate suspended sludge and impurities from the clear water, achieving water purification and sludge enrichment. The sludge interface is the critical boundary between the water and sludge within the sedimentation tank, and it is a core parameter characterizing sludge settling efficiency and sludge accumulation thickness. The sludge interface is closely linked to the control logic of sedimentation tank sludge discharge start / stop and discharge duration. If the underwater depth detection of the sludge interface deviates significantly, problems such as incomplete sludge discharge leading to sludge accumulation, excessive sludge discharge causing water waste, and substandard water quality can easily occur. Therefore, the accuracy of sludge interface detection is a crucial basis for ensuring the stability of water treatment processes and achieving effluent quality standards.

[0003] Currently, single-frequency ultrasonic testing is commonly used to detect sludge interfaces. Specifically, a fixed-frequency ultrasonic beam is emitted into the sedimentation tank. The difference in propagation speed and attenuation characteristics of ultrasonic waves in clean water and sludge is utilized. By analyzing the propagation time of the echo signal reflected from the sludge interface, the underwater depth of the sludge interface is calculated. However, in the actual operation of sedimentation tanks, there is a sludge-water mixing zone. This mixing zone interferes with the normal propagation of the single-frequency ultrasonic waves, preventing them from reaching the sludge interface or causing premature reflection. This leads to a deviation between the calculated sludge interface location and the actual location, reducing the accuracy of the sludge interface detection. Summary of the Invention

[0004] This application provides a method and apparatus for detecting sludge interfaces in sedimentation tanks, which improves the detection accuracy of sludge interfaces.

[0005] The first aspect of this application provides a method for detecting the sludge interface in a sedimentation tank, comprising: A dataset of echo signals reflected back after a multi-frequency ultrasonic signal is incident on a sedimentation tank is obtained. The multi-frequency ultrasonic signal includes an ultrasonic signal of a first frequency, an ultrasonic signal of a second frequency, and an ultrasonic signal of a third frequency, wherein the second frequency is greater than the third frequency and less than the first frequency. Extract the echo features of each echo signal data in the echo signal dataset, and construct an echo feature fusion matrix based on each echo feature; The echo feature fusion matrix is ​​compared with the feature threshold ranges corresponding to the three different media layers in the sedimentation tank. Based on the comparison results, the echo features corresponding to each media layer in the echo feature fusion matrix are determined. The three media layers are the clear water layer, the transition layer, and the sludge layer distributed along the longitudinal direction of the sedimentation tank. The real-time temperature and real-time sludge concentration values ​​of each media layer are obtained, and the real-time temperature and real-time sludge concentration values ​​of each media layer are input into a preset propagation speed correction model to obtain the actual propagation speed of the multi-frequency ultrasonic signal in each media layer. The first propagation path distance of the clear water layer and the second propagation path distance of the transition layer are calculated based on the actual propagation speed and corresponding echo characteristics of each medium layer. The underwater depth of the sludge interface in the sedimentation tank is determined based on the sum of the first propagation path distance and the second propagation path distance.

[0006] Optionally, the step of calculating the first propagation path distance of the clear water layer and the second propagation path distance of the transition layer based on the actual propagation velocity and corresponding echo characteristics of each medium layer includes: The initial propagation path distance of each medium layer is calculated based on the original propagation velocity and the original propagation time in the echo characteristics of each medium layer. The original propagation velocity is the set value of the propagation velocity of the multi-frequency ultrasonic signal in the sedimentation tank. The propagation time of each medium layer is calculated based on the actual propagation speed corresponding to each medium layer and the initial propagation path distance corresponding to each medium layer. The effective propagation time threshold range for each medium layer is determined based on the actual propagation speed corresponding to each medium layer. The initial propagation path distance of each medium layer is corrected by comparing the propagation time of each medium layer with the effective propagation time threshold range, so as to obtain the target propagation path distance of each medium layer. The target propagation path distance of the clear water layer is the first propagation path distance, and the target propagation path distance of the transition layer is the second propagation path distance.

[0007] Optionally, determining the effective propagation time threshold range based on the actual propagation speed corresponding to each medium layer includes: The actual propagation speed corresponding to each medium layer is compared with the preset propagation speed threshold range, and the adjustment coefficient of each medium layer is determined based on the comparison results. The effective propagation time threshold range of each medium layer is obtained by comparing the adjustment coefficient of each medium layer with the preset propagation time threshold range.

[0008] Optionally, the step of correcting the initial propagation path distance of each medium layer by comparing the propagation time of each medium layer with the effective propagation time threshold range to obtain the target propagation path distance of each medium layer includes: Obtain the preset mapping relationship between propagation time and path correction coefficient; If the propagation time of the current medium layer is within the effective propagation time threshold range, then the target propagation path distance of the current medium layer is determined as the initial propagation path distance of the current medium layer; If the propagation time of the current medium layer is greater than the upper limit of the effective propagation time threshold range, then the gain coefficient is determined according to the mapping relationship between the propagation time and the path correction coefficient, and the target propagation path distance of the current medium layer is determined to be the product of the initial propagation path distance of the current medium layer and the gain coefficient. If the propagation time of the current medium layer is less than the lower limit of the effective propagation time threshold range, then the attenuation coefficient is determined according to the mapping relationship between the propagation time and the path correction coefficient, and the target propagation path distance of the current medium layer is determined to be the product of the initial propagation path distance of the current medium layer and the attenuation coefficient.

[0009] Optionally, the step of inputting the real-time temperature value and the real-time sludge concentration value of each media layer into a preset propagation velocity correction model to obtain the actual propagation velocity of the multi-frequency ultrasonic signal in each media layer includes: The preset propagation velocity correction model is initialized based on the preset reference temperature and preset reference concentration values ​​of each medium layer; The real-time temperature value and real-time sludge concentration value of each media layer are input into the preset propagation velocity correction model; The temperature difference between the real-time temperature value and the corresponding preset reference temperature value of each media layer, as well as the concentration difference between the real-time sludge concentration value and the corresponding preset reference concentration value of each media layer, are calculated using the preset propagation speed correction model. The preset propagation speed correction model determines the temperature correction coefficient and the concentration correction coefficient based on the temperature difference and the concentration difference. The original propagation speed is then corrected based on the temperature correction coefficient and the concentration correction coefficient of each medium layer, and the actual propagation speed of the multi-frequency ultrasonic signal in each medium layer is output.

[0010] A second aspect of this application provides a device for detecting the sludge interface in a sedimentation tank, comprising: The acquisition unit is used to acquire a dataset of echo signals reflected back after a multi-frequency ultrasonic signal is incident on a sedimentation tank. The multi-frequency ultrasonic signal includes an ultrasonic signal of a first frequency, an ultrasonic signal of a second frequency, and an ultrasonic signal of a third frequency, wherein the second frequency is greater than the third frequency and less than the first frequency. The extraction unit is used to extract the echo features of each echo signal data in the echo signal dataset and construct an echo feature fusion matrix based on each echo feature; The determining unit is used to compare the echo feature fusion matrix with the feature threshold intervals corresponding to the three different media layers in the sedimentation tank, and determine the echo features corresponding to each media layer in the echo feature fusion matrix according to the comparison results. The three media layers are the clear water layer, the transition layer and the sludge layer distributed along the longitudinal direction of the sedimentation tank. The input unit is used to acquire the real-time temperature value and real-time sludge concentration value of each medium layer, and input the real-time temperature value and real-time sludge concentration value of each medium layer into the preset propagation speed correction model to obtain the actual propagation speed of the multi-frequency ultrasonic signal in each medium layer. The calculation unit is used to calculate the first propagation path distance of the clear water layer and the second propagation path distance of the transition layer based on the actual propagation speed and corresponding echo characteristics of each medium layer, and to determine the underwater depth of the sludge interface in the sedimentation tank based on the sum of the first propagation path distance and the second propagation path distance.

[0011] Optionally, the calculation unit calculates the first propagation path distance of the clear water layer and the second propagation path distance of the transition layer based on the actual propagation velocity and corresponding echo characteristics of each medium layer, including: The initial propagation path distance of each medium layer is calculated based on the original propagation velocity and the original propagation time in the echo characteristics of each medium layer. The original propagation velocity is the set value of the propagation velocity of the multi-frequency ultrasonic signal in the sedimentation tank. The propagation time of each medium layer is calculated based on the actual propagation speed corresponding to each medium layer and the initial propagation path distance corresponding to each medium layer. The effective propagation time threshold range for each medium layer is determined based on the actual propagation speed corresponding to each medium layer. The initial propagation path distance of each medium layer is corrected by comparing the propagation time of each medium layer with the effective propagation time threshold range, so as to obtain the target propagation path distance of each medium layer. The target propagation path distance of the clear water layer is the first propagation path distance, and the target propagation path distance of the transition layer is the second propagation path distance.

[0012] Optionally, the input unit inputs the real-time temperature value and the real-time sludge concentration value of each media layer into a preset propagation speed correction model to obtain the actual propagation speed of the multi-frequency ultrasonic signal in each media layer, including: The preset propagation velocity correction model is initialized based on the preset reference temperature and preset reference concentration values ​​of each medium layer; The real-time temperature value and real-time sludge concentration value of each media layer are input into the preset propagation velocity correction model; The temperature difference between the real-time temperature value and the corresponding preset reference temperature value of each media layer, as well as the concentration difference between the real-time sludge concentration value and the corresponding preset reference concentration value of each media layer, are calculated using the preset propagation speed correction model. The preset propagation speed correction model calculates temperature correction coefficients and concentration correction coefficients based on the temperature difference and concentration difference, and corrects the original propagation speed based on the temperature correction coefficients and concentration correction coefficients of each medium layer, outputting the actual propagation speed of the multi-frequency ultrasonic signal in each medium layer.

[0013] A third aspect of this application provides an electronic device, comprising: Processor, memory, input / output units, and bus; The processor is connected to the memory, the input / output unit, and the bus; The memory stores a program, which the processor calls to execute a method for detecting the sludge interface in a sedimentation tank, as described in the first aspect and any optional method in the first aspect.

[0014] A fourth aspect of this application provides a computer-readable storage medium comprising: instructions that, when executed on a computer, cause the computer to perform a method for detecting a sludge interface in a sedimentation tank as described in the first aspect and any optional method described in the first aspect.

[0015] As can be seen from the above technical solutions, this application has the following effects: First, a dataset of echo signals reflected back from the sedimentation tank after multi-frequency ultrasonic signals are incident on it is acquired. This dataset includes ultrasonic signals of a first frequency, a second frequency, and a third frequency, where the second frequency is greater than the third frequency but less than the first frequency. Then, echo features of each echo signal in the dataset are extracted, and an echo feature fusion matrix is ​​constructed based on these features. Next, the echo feature fusion matrix is ​​compared with the feature threshold intervals corresponding to the three different media layers in the sedimentation tank. Based on the comparison results, the echo features corresponding to each media layer in the echo feature fusion matrix are determined. The three media layers are a clear water layer, a transition layer, and a sludge layer distributed longitudinally along the sedimentation tank. Real-time temperature and sludge concentration values ​​for each media layer are obtained and input into a preset propagation velocity correction model to obtain the actual propagation velocity of the multi-frequency ultrasonic signal in each media layer. Finally, based on the actual propagation velocity and echo characteristics of each media layer, the first propagation path distance of the clear water layer and the second propagation path distance of the transition layer are calculated. The underwater depth of the sludge interface in the sedimentation tank is determined by the sum of the first and second propagation path distances.

[0016] Based on this, multi-frequency ultrasonic signal collaborative acquisition and feature fusion can be achieved, leveraging the different penetration and reflection characteristics of ultrasonic signals at different frequencies to achieve complementary advantages. By combining the layered characteristic threshold range matching of different media layers, interference from factors such as bubbles, suspended impurities, and mechanical vibrations can be effectively filtered out, accurately distinguishing the clear water layer, transition layer, and sedimentation layer. This solves the problem of sludge interface ambiguity and misjudgment caused by the transition layer formed by mud-water mixing. Furthermore, by using the real-time temperature and sludge concentration values ​​of each media layer, the ultrasonic propagation speed can be layered to obtain the actual propagation speed of the ultrasonic signal in different media layers. This allows for the quantification of the impact of complex operating conditions such as water temperature fluctuations and uneven sludge concentration in the sedimentation tank on the ultrasonic propagation speed, making the propagation speed value more closely reflect actual operating conditions, improving the accuracy of propagation path distance calculation, and thus enhancing the detection accuracy of the sludge interface. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating a method for detecting the sludge interface in a sedimentation tank according to this application. Figure 2 This is a schematic diagram of the structure of a sludge interface detection device for sedimentation tanks according to this application; Figure 3 This is a schematic diagram of the structure of an electronic device according to this application. Detailed Implementation

[0018] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0019] It should be understood that, when used in this application specification, the term "comprising" indicates the presence of the described feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof.

[0020] It should also be understood that the term “and / or” as used in this application specification means any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0021] As used in this application specification, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [the described condition or event] is detected," or "in response to detection of [the described condition or event]."

[0022] Furthermore, in the description of this application, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0024] Sedimentation tanks are key solid-liquid separation devices in wastewater treatment, tap water purification, and industrial water treatment processes. They rely on gravity settling to separate suspended sludge and impurities from the clear water, achieving water purification and sludge enrichment. The sludge interface is the critical boundary between the water and sludge within the sedimentation tank, and it is a core parameter characterizing sludge settling efficiency and sludge accumulation thickness. The sludge interface is closely linked to the control logic of sedimentation tank sludge discharge start / stop and discharge duration. If the underwater depth detection of the sludge interface deviates significantly, problems such as incomplete sludge discharge leading to sludge accumulation, excessive sludge discharge causing water waste, and substandard water quality can easily occur. Therefore, the accuracy of sludge interface detection is a crucial basis for ensuring the stability of water treatment processes and achieving effluent quality standards.

[0025] Currently, single-frequency ultrasonic testing is commonly used to detect sludge interfaces. Specifically, a fixed-frequency ultrasonic beam is emitted into the sedimentation tank. The difference in propagation speed and attenuation characteristics of ultrasonic waves in clean water and sludge is utilized. By analyzing the propagation time of the echo signal reflected from the sludge interface, the underwater depth of the sludge interface is calculated. However, in the actual operation of sedimentation tanks, there is a sludge-water mixing zone. This mixing zone interferes with the normal propagation of the single-frequency ultrasonic waves, preventing them from reaching the sludge interface or causing premature reflection. This leads to a deviation between the calculated sludge interface location and the actual location, reducing the accuracy of the sludge interface detection.

[0026] To address the aforementioned issues, this application provides a method and apparatus for detecting sludge interfaces in sedimentation tanks, thereby improving the detection accuracy of sludge interfaces.

[0027] Please see Figure 1 As shown in the embodiment of this application, a method for detecting the sludge interface in a sedimentation tank includes: 101. Obtain the dataset of echo signals reflected back after multi-frequency ultrasonic signals are incident on the sedimentation tank. The multi-frequency ultrasonic signals include ultrasonic signals of a first frequency, ultrasonic signals of a second frequency, and ultrasonic signals of a third frequency, wherein the second frequency is greater than the third frequency and less than the first frequency.

[0028] The multi-frequency ultrasonic signal includes three pulsed ultrasonic signals of different fixed frequencies: a first frequency ultrasonic signal, a second frequency ultrasonic signal, and a third frequency ultrasonic signal. The first frequency ultrasonic signal can be a high-frequency ultrasonic signal; the second frequency ultrasonic signal can be a mid-frequency ultrasonic signal; and the third frequency ultrasonic signal can be a low-frequency ultrasonic signal. It is understandable that the penetration and resolution characteristics of ultrasonic signals propagating in different media are strongly correlated with frequency. High-frequency ultrasonic signals have short wavelengths and high spatial resolution, accurately capturing subtle interface changes, but have poor penetration and are difficult to penetrate high-concentration sludge media. Mid-frequency ultrasonic signals offer balanced performance, balancing resolution and penetration, and can stably penetrate sludge-water mixing areas. Low-frequency ultrasonic signals have long wavelengths and extremely strong penetration, penetrating high-concentration, thick sludge media, but have lower resolution and are difficult to identify thin-layer interfaces. Therefore, the differentiated penetration capabilities and resolution characteristics of ultrasonic signals of different fixed frequencies can be utilized to adapt to the detection needs of media layers with different densities in sedimentation tanks.

[0029] Specifically, a multi-frequency ultrasonic monitoring device is installed at a fixed point above the sedimentation tank surface. This device integrates three transducers: high-frequency (e.g., 2MHz), medium-frequency (e.g., 500kHz), and low-frequency (e.g., 100kHz). After initial configuration, the three transducers are controlled to transmit ultrasonic signals to the sedimentation tank surface in a time-sharing manner, and the echo signal data returned from the transmission is received synchronously to generate an echo signal dataset.

[0030] 102. Extract the echo features of each echo signal data in the echo signal dataset, and construct an echo feature fusion matrix based on each echo feature.

[0031] Specifically, after acquiring the echo signal dataset, the echo signal data in the dataset is first preprocessed, such as by filtering or noise reduction. Then, the echo features are extracted from the preprocessed echo signal data. These echo features can include amplitude, propagation time, and attenuation coefficient. It should be noted that amplitude represents the maximum voltage amplitude of the echo signal, used to characterize the signal reflection intensity; propagation time represents the total duration from transmission to reception of the reflected signal; and the attenuation coefficient represents the signal loss rate of the ultrasonic signal per unit distance propagated in the medium.

[0032] Specifically, an echo feature fusion matrix is ​​constructed using three ultrasonic signals of different frequencies as the row dimension and echo features as the column dimension. Each row of the echo feature fusion matrix corresponds to all echo features of a single-frequency ultrasonic signal, and each column corresponds to ultrasonic signals of different frequencies for a single echo feature.

[0033] 103. Compare the echo feature fusion matrix with the feature threshold ranges corresponding to the three different media layers in the sedimentation tank. Based on the comparison results, determine the echo features corresponding to each media layer in the echo feature fusion matrix. The three media layers are the clear water layer, the transition layer, and the sludge layer distributed longitudinally along the sedimentation tank.

[0034] The clear water layer is a uniform and clean water medium with a sludge concentration of approximately zero. Ultrasonic wave propagation loss is extremely low, typically exhibiting short propagation time, high amplitude, and low attenuation echo characteristics. The characteristic threshold range for the clear water layer is determined based on these echo characteristics. The transition layer is a solid-liquid mixed gradient medium with a large sludge concentration gradient, exhibiting intermediate transitional echo characteristics. The characteristic threshold range for the transition layer is determined based on these echo characteristics. The sludge layer is a solid particulate medium with a high sludge concentration, exhibiting strong scattering and absorption of ultrasonic signals. It typically exhibits long propagation time, low amplitude, and high attenuation echo characteristics. The characteristic threshold range for the sludge layer is determined based on these echo characteristics.

[0035] Specifically, each echo feature in the echo feature fusion matrix is ​​compared with the feature threshold ranges of different media layers. For example: if the echo features of the first frequency ultrasonic signal all fall within the feature threshold range of the clear water layer, then the media layer currently detected by the first frequency ultrasonic signal can be determined to be the clear water layer; if the echo features of the second frequency ultrasonic signal all fall within the feature threshold range of the transition layer, then the media layer currently detected by the second frequency ultrasonic signal can be determined to be the transition layer; if the echo features of the third frequency ultrasonic signal all fall within the feature threshold range of the sludge layer, then the media layer currently detected by the third frequency ultrasonic signal can be determined to be the sludge layer.

[0036] 104. Obtain the real-time temperature and sludge concentration values ​​of each media layer, and input the real-time temperature and sludge concentration values ​​of each media layer into the preset propagation speed correction model to obtain the actual propagation speed of the multi-frequency ultrasonic signal in each media layer.

[0037] The real-time temperature value represents the current water temperature of each media layer in the sedimentation tank. Water temperature directly affects the density of the media; the higher the water temperature, the faster the ultrasonic wave propagates. Therefore, it can be considered one of the factors influencing the determination of ultrasonic wave propagation speed. The real-time sludge concentration value represents the current suspended sludge solids content of each media layer. The higher the sludge concentration, the greater the equivalent density of the media, and the more significant the attenuation of ultrasonic wave propagation speed. Therefore, it can also be considered one of the factors influencing the determination of ultrasonic wave propagation speed.

[0038] Specifically, temperature sensors and turbidity concentration sensors are deployed at multiple fixed depth points in the sedimentation tank to simultaneously collect real-time temperature and sludge concentration values ​​at the corresponding fixed depth points. Based on the depth range scales of the clear water layer, transition layer, and sludge layer determined by the echo signal dataset, the media layer to which the real-time temperature and sludge concentration values ​​collected at each vertical fixed depth point belong are identified. When the positions of the clear water layer, transition layer, and sludge layer change due to variations in sludge thickness in the sedimentation tank, the fixed depth coordinates of each fixed depth point are matched one by one with the updated depth ranges of each media layer. If the fixed depth coordinates fall within the clear water layer depth range, the corresponding measurement data belongs to the clear water layer; if the fixed depth coordinates fall within the transition layer depth range, the corresponding measurement data belongs to the transition layer; and if the fixed depth coordinates fall within the sludge layer depth range, the corresponding measurement data belongs to the sludge layer. Simultaneously, the real-time temperature and sludge concentration values ​​are matched with the inherent temperature thresholds and inherent sludge concentration thresholds of the three media layers for secondary verification. If the deviation value is greater than the preset range, the depth range of each media layer is corrected by gradient interpolation of the temperature value and sludge concentration value of adjacent depth points, so as to further determine the real-time temperature value and real-time sludge concentration value of each media layer.

[0039] In some embodiments, the real-time temperature value and real-time sludge concentration value of each media layer are input into a preset propagation velocity correction model to obtain the actual propagation velocity of the multi-frequency ultrasonic signal in each media layer, including: The preset propagation velocity correction model is initialized based on the preset reference temperature and preset reference concentration values ​​of each medium layer; Input the real-time temperature and real-time sludge concentration values ​​of each media layer into the preset propagation velocity correction model; The temperature difference between the real-time temperature value of each media layer and the corresponding preset reference temperature value, as well as the concentration difference between the real-time sludge concentration value of each media layer and the corresponding preset reference concentration value, are calculated using a preset propagation speed correction model. By using a preset propagation speed correction model to determine temperature correction coefficients and concentration correction coefficients based on temperature and concentration differences, the original propagation speed is corrected based on the temperature and concentration correction coefficients of each medium layer, and the actual propagation speed of the multi-frequency ultrasonic signal in each medium layer is output.

[0040] The original propagation speed is the reference propagation speed of the ultrasonic signal in a conventional clean water medium, and it is a fixed set value. The preset reference temperature and preset reference concentration are conventional parameters of the ambient temperature steady-state sedimentation tank in different medium layers. They can be understood as the real-time temperature and real-time sludge concentration of a medium layer when the propagation speed of the ultrasonic signal in a single medium layer is the original propagation speed. These values ​​can be obtained from historical measurement data.

[0041] Specifically, firstly, the preset reference temperature and concentration values ​​for each medium layer are written into the underlying parameter library of the preset propagation velocity correction model to complete the parameter initialization of the preset propagation velocity correction model and determine the basic calculation benchmark of the preset propagation velocity correction model. Then, the temperature difference and concentration difference values ​​of each medium layer in the preset propagation velocity correction model are used to quantify the operating condition fluctuation amplitude of each medium layer. Next, the temperature correction coefficient corresponding to the temperature difference and the concentration correction coefficient corresponding to the concentration difference are calculated through a preset calibration fitting algorithm. Through the double superposition correction of the temperature correction coefficient and the concentration correction coefficient, the actual propagation velocity of the multi-frequency ultrasonic signal in each medium layer is output.

[0042] 105. Calculate the first propagation path distance of the clear water layer and the second propagation path distance of the transition layer based on the actual propagation speed and corresponding echo characteristics of each medium layer, and determine the underwater depth of the sludge interface in the sedimentation tank according to the sum of the first propagation path distance and the second propagation path distance.

[0043] The first propagation path distance is the total distance the ultrasonic signal travels back and forth in the clear water layer, and the second propagation path distance is the total distance the ultrasonic signal travels from the water surface to the critical interface between the clear water layer and the transition layer. The third propagation path distance is the total distance the ultrasonic signal travels back and forth in the transition layer, and the fourth propagation path distance is the vertical distance the ultrasonic signal travels from the bottom of the clear water layer to the critical interface between the transition layer and the sludge layer. The sludge interface is the critical interface between the transition layer and the sludge layer.

[0044] Specifically, after calculating the first propagation path distance of the clear water layer and the second propagation path distance of the transition layer using the actual propagation speed and corresponding echo characteristics of each medium layer, the first propagation path distance and the second propagation path distance are summed, and the sum is multiplied by one-half to calculate the underwater depth of the sludge interface.

[0045] In some embodiments, calculating the first propagation path distance of the clear water layer and the second propagation path distance of the transition layer based on the actual propagation velocity and corresponding echo characteristics of each medium layer includes: The initial propagation path distance of each medium layer is calculated based on the original propagation velocity and the original propagation time in the echo characteristics of each medium layer. The original propagation velocity is the set value of the propagation velocity of the multi-frequency ultrasonic signal in the sedimentation tank. The propagation time of each medium layer is calculated based on the actual propagation speed of each medium layer and the initial propagation path distance of each medium layer. The effective propagation time threshold range for each medium layer is determined based on the actual propagation speed corresponding to each medium layer. The initial propagation path distance of each medium layer is corrected by comparing the propagation time of each medium layer with the effective propagation time threshold range, so as to obtain the target propagation path distance of each medium layer. The target propagation path distance of the clear water layer is the first propagation path distance, and the target propagation path distance of the transition layer is the second propagation path distance.

[0046] Specifically, the original propagation time is the time taken from the emission of the ultrasonic signal to the reception of the reflected signal, extracted from the echo characteristics of each medium layer. Multiplying the original propagation speed by the original propagation time of each medium layer yields the initial propagation path.

[0047] Specifically, the initial propagation path of each medium layer is corrected using the actual propagation speed corresponding to each medium layer. That is, the initial propagation path of the current medium layer is divided by the actual propagation speed of that medium layer to calculate the propagation time to that medium layer. This allows for the determination of the true propagation time for each medium layer, thus eliminating the time calculation deviation caused by a fixed sound speed.

[0048] Furthermore, the effective propagation time threshold range is determined based on the actual propagation speed corresponding to each medium layer, including: The actual propagation speed of each medium layer is compared with the preset propagation speed threshold range, and the adjustment coefficient of each medium layer is determined based on the comparison results. The effective propagation time threshold range of each medium layer is obtained by comparing the adjustment coefficient of each medium layer with the preset propagation time threshold range.

[0049] In this study, ultrasonic propagation time is negatively correlated with propagation speed. Fluctuations in sound speed directly cause a shift in the propagation time reference, making a fixed time threshold unsuitable for dynamically changing media layers. In this embodiment, sound speed fluctuations are quantified by comparing the actual propagation speed of each media layer with a preset propagation speed threshold range. This fluctuation is then converted into an adjustment coefficient for the propagation time threshold. The preset propagation time threshold range is dynamically corrected based on the deviation between the actual propagation speed and the preset propagation speed threshold range to avoid time misjudgments caused by sound speed fluctuations.

[0050] Furthermore, the initial propagation path distance of each medium layer is corrected by comparing the propagation time of each medium layer with the effective propagation time threshold range, thus obtaining the target propagation path distance of each medium layer, including: Obtain the preset mapping relationship between propagation time and path correction coefficient; If the current propagation time of the medium layer is within the effective propagation time threshold range, then the target propagation path distance of the current medium layer is determined as the initial propagation path distance of the current medium layer. If the propagation time of the current medium layer is greater than the upper limit of the effective propagation time threshold range, the gain coefficient is determined according to the mapping relationship between propagation time and path correction coefficient, and the target propagation path distance of the current medium layer is determined as the product of the initial propagation path distance of the current medium layer and the gain coefficient. If the propagation time of the current medium layer is less than the lower limit of the effective propagation time threshold range, the attenuation coefficient is determined according to the mapping relationship between propagation time and path correction coefficient. The target propagation path distance of the current medium layer is determined as the product of the initial propagation path distance of the current medium layer and the attenuation coefficient.

[0051] Among them, the mapping relationship between propagation time and path correction coefficient is a database of correspondences between pre-calibrated time deviation and distance correction coefficient, which includes two types of correction parameters: gain coefficient and attenuation coefficient.

[0052] Specifically, the propagation time of each media layer is compared with the effective propagation time threshold range to determine the propagation time deviation of each media layer. Then, based on different propagation time deviation states, corresponding correction coefficients are matched to adaptively compensate and correct the initial propagation path distance, so as to reduce the interference of instantaneous conditions such as water flow fluctuations, microbubbles, or uneven local sludge concentration, thereby further improving the detection accuracy of the sludge interface.

[0053] Please see Figure 2 As shown, an embodiment of this application includes a device for detecting the sludge interface in a sedimentation tank, comprising: The acquisition unit 201 is used to acquire a dataset of echo signals reflected back after a multi-frequency ultrasonic signal is incident on a sedimentation tank. The multi-frequency ultrasonic signal includes an ultrasonic signal of a first frequency, an ultrasonic signal of a second frequency, and an ultrasonic signal of a third frequency, wherein the second frequency is greater than the third frequency and less than the first frequency. Extraction unit 202 is used to extract the echo features of each echo signal data in the echo signal dataset and construct an echo feature fusion matrix based on each echo feature; The determination unit 203 is used to compare the echo feature fusion matrix with the feature threshold ranges corresponding to the three different media layers in the sedimentation tank, and determine the echo features corresponding to each media layer in the echo feature fusion matrix according to the comparison results. The three media layers are the clear water layer, the transition layer and the sludge layer distributed along the longitudinal direction of the sedimentation tank. Input unit 204 is used to acquire the real-time temperature value and real-time sludge concentration value of each medium layer, and input the real-time temperature value and real-time sludge concentration value of each medium layer into the preset propagation speed correction model to obtain the actual propagation speed of the multi-frequency ultrasonic signal in each medium layer. The calculation unit 205 is used to calculate the first propagation path distance of the clear water layer and the second propagation path distance of the transition layer based on the actual propagation speed and corresponding echo characteristics of each medium layer, and to determine the underwater depth of the sludge interface in the sedimentation tank based on the sum of the first propagation path distance and the second propagation path distance.

[0054] Please see Figure 3 As shown, the electronic device in this application embodiment includes: Processor 301, memory 302, input / output unit 303, and bus 304; The processor 301 is connected to the memory 302, the input / output unit 303, and the bus 304; The memory 302 stores a program, and the processor 301 calls the program to execute the sedimentation tank sludge interface detection method in any of the aforementioned optional embodiments.

[0055] This application also provides a computer-readable storage medium, including: instructions that, when executed on a computer, cause the computer to perform the sedimentation tank sludge interface detection method in any of the foregoing optional embodiments.

[0056] In the description of this specification, the references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0057] Furthermore, the above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for detecting the sludge interface in a sedimentation tank, characterized in that, include: A dataset of echo signals reflected back after a multi-frequency ultrasonic signal is incident on a sedimentation tank is obtained. The multi-frequency ultrasonic signal includes an ultrasonic signal of a first frequency, an ultrasonic signal of a second frequency, and an ultrasonic signal of a third frequency, wherein the second frequency is greater than the third frequency and less than the first frequency. Extract the echo features of each echo signal data in the echo signal dataset, and construct an echo feature fusion matrix based on each echo feature; The echo feature fusion matrix is ​​compared with the feature threshold ranges corresponding to the three different media layers in the sedimentation tank. Based on the comparison results, the echo features corresponding to each media layer in the echo feature fusion matrix are determined. The three media layers are the clear water layer, the transition layer, and the sludge layer distributed along the longitudinal direction of the sedimentation tank. The real-time temperature and real-time sludge concentration values ​​of each media layer are obtained, and the real-time temperature and real-time sludge concentration values ​​of each media layer are input into a preset propagation speed correction model to obtain the actual propagation speed of the multi-frequency ultrasonic signal in each media layer. The first propagation path distance of the clear water layer and the second propagation path distance of the transition layer are calculated based on the actual propagation speed and corresponding echo characteristics of each medium layer. The underwater depth of the sludge interface in the sedimentation tank is determined based on the sum of the first propagation path distance and the second propagation path distance.

2. The method for detecting the sludge interface in a sedimentation tank according to claim 1, characterized in that, The calculation of the first propagation path distance of the clear water layer and the second propagation path distance of the transition layer based on the actual propagation velocity and corresponding echo characteristics of each medium layer includes: The initial propagation path distance of each medium layer is calculated based on the original propagation velocity and the original propagation time in the echo characteristics of each medium layer. The original propagation velocity is the set value of the propagation velocity of the multi-frequency ultrasonic signal in the sedimentation tank. The propagation time of each medium layer is calculated based on the actual propagation speed corresponding to each medium layer and the initial propagation path distance corresponding to each medium layer. The effective propagation time threshold range for each medium layer is determined based on the actual propagation speed corresponding to each medium layer. The initial propagation path distance of each medium layer is corrected by comparing the propagation time of each medium layer with the effective propagation time threshold range, so as to obtain the target propagation path distance of each medium layer. The target propagation path distance of the clear water layer is the first propagation path distance, and the target propagation path distance of the transition layer is the second propagation path distance.

3. The method for detecting the sludge interface in a sedimentation tank according to claim 2, characterized in that, The determination of the effective propagation time threshold range based on the actual propagation speed corresponding to each medium layer includes: The actual propagation speed corresponding to each medium layer is compared with the preset propagation speed threshold range, and the adjustment coefficient of each medium layer is determined based on the comparison results. The effective propagation time threshold range of each medium layer is obtained by comparing the adjustment coefficient of each medium layer with the preset propagation time threshold range.

4. The method for detecting the sludge interface in a sedimentation tank according to claim 2, characterized in that, The initial propagation path distance of each medium layer is corrected by comparing the propagation time of each medium layer with the effective propagation time threshold range to obtain the target propagation path distance of each medium layer, including: Obtain the preset mapping relationship between propagation time and path correction coefficient; If the propagation time of the current medium layer is within the effective propagation time threshold range, then the target propagation path distance of the current medium layer is determined as the initial propagation path distance of the current medium layer; If the propagation time of the current medium layer is greater than the upper limit of the effective propagation time threshold range, then the gain coefficient is determined according to the mapping relationship between the propagation time and the path correction coefficient, and the target propagation path distance of the current medium layer is determined to be the product of the initial propagation path distance of the current medium layer and the gain coefficient. If the propagation time of the current medium layer is less than the lower limit of the effective propagation time threshold range, then the attenuation coefficient is determined according to the mapping relationship between the propagation time and the path correction coefficient, and the target propagation path distance of the current medium layer is determined to be the product of the initial propagation path distance of the current medium layer and the attenuation coefficient.

5. The method for detecting the sludge interface in a sedimentation tank according to claim 1, characterized in that, The step of inputting the real-time temperature value and the real-time sludge concentration value of each media layer into a preset propagation velocity correction model to obtain the actual propagation velocity of the multi-frequency ultrasonic signal in each media layer includes: The preset propagation velocity correction model is initialized based on the preset reference temperature and preset reference concentration values ​​of each medium layer; The real-time temperature value and real-time sludge concentration value of each media layer are input into the preset propagation velocity correction model; The temperature difference between the real-time temperature value and the corresponding preset reference temperature value of each media layer, as well as the concentration difference between the real-time sludge concentration value and the corresponding preset reference concentration value of each media layer, are calculated using the preset propagation speed correction model. The preset propagation speed correction model determines the temperature correction coefficient and the concentration correction coefficient based on the temperature difference and the concentration difference. The original propagation speed is then corrected based on the temperature correction coefficient and the concentration correction coefficient of each medium layer, and the actual propagation speed of the multi-frequency ultrasonic signal in each medium layer is output.

6. A device for detecting the sludge interface in a sedimentation tank, characterized in that, include: The acquisition unit is used to acquire a dataset of echo signals reflected back after a multi-frequency ultrasonic signal is incident on a sedimentation tank. The multi-frequency ultrasonic signal includes an ultrasonic signal of a first frequency, an ultrasonic signal of a second frequency, and an ultrasonic signal of a third frequency, wherein the second frequency is greater than the third frequency and less than the first frequency. The extraction unit is used to extract the echo features of each echo signal data in the echo signal dataset and construct an echo feature fusion matrix based on each echo feature; The determining unit is used to compare the echo feature fusion matrix with the feature threshold intervals corresponding to the three different media layers in the sedimentation tank, and determine the echo features corresponding to each media layer in the echo feature fusion matrix according to the comparison results. The three media layers are the clear water layer, the transition layer and the sludge layer distributed along the longitudinal direction of the sedimentation tank. The input unit is used to acquire the real-time temperature value and real-time sludge concentration value of each medium layer, and input the real-time temperature value and real-time sludge concentration value of each medium layer into the preset propagation speed correction model to obtain the actual propagation speed of the multi-frequency ultrasonic signal in each medium layer. The calculation unit is used to calculate the first propagation path distance of the clear water layer and the second propagation path distance of the transition layer based on the actual propagation speed and corresponding echo characteristics of each medium layer, and to determine the underwater depth of the sludge interface in the sedimentation tank based on the sum of the first propagation path distance and the second propagation path distance.

7. The device for detecting the sludge interface in a sedimentation tank according to claim 6, characterized in that, The calculation unit calculates the first propagation path distance of the clear water layer and the second propagation path distance of the transition layer based on the actual propagation velocity and corresponding echo characteristics of each medium layer, including: The initial propagation path distance of each medium layer is calculated based on the original propagation velocity and the original propagation time in the echo characteristics of each medium layer. The original propagation velocity is the set value of the propagation velocity of the multi-frequency ultrasonic signal in the sedimentation tank. The propagation time of each medium layer is calculated based on the actual propagation speed corresponding to each medium layer and the initial propagation path distance corresponding to each medium layer. The effective propagation time threshold range for each medium layer is determined based on the actual propagation speed corresponding to each medium layer. The initial propagation path distance of each medium layer is corrected by comparing the propagation time of each medium layer with the effective propagation time threshold range, so as to obtain the target propagation path distance of each medium layer. The target propagation path distance of the clear water layer is the first propagation path distance, and the target propagation path distance of the transition layer is the second propagation path distance.

8. The device for detecting the sludge interface in a sedimentation tank according to claim 6, characterized in that, The input unit inputs the real-time temperature values ​​and real-time sludge concentration values ​​of each media layer into a preset propagation speed correction model to obtain the actual propagation speed of the multi-frequency ultrasonic signal in each media layer, including: The preset propagation velocity correction model is initialized based on the preset reference temperature and preset reference concentration values ​​of each medium layer; The real-time temperature value and real-time sludge concentration value of each media layer are input into the preset propagation velocity correction model; The temperature difference between the real-time temperature value and the corresponding preset reference temperature value of each media layer, as well as the concentration difference between the real-time sludge concentration value and the corresponding preset reference concentration value of each media layer, are calculated using the preset propagation speed correction model. The preset propagation speed correction model calculates temperature correction coefficients and concentration correction coefficients based on the temperature difference and concentration difference, and corrects the original propagation speed based on the temperature correction coefficients and concentration correction coefficients of each medium layer, outputting the actual propagation speed of the multi-frequency ultrasonic signal in each medium layer.

9. An electronic device, characterized in that, include: Processor, memory, input / output units, and bus; The processor is connected to the memory, the input / output unit, and the bus; The memory stores a program, which the processor calls to execute the method for detecting the sludge interface in a sedimentation tank as described in any one of claims 1 to 5.

10. A computer-readable storage medium, characterized in that, include: Instructions, when executed on a computer, cause the computer to perform the method for detecting the sludge interface in a sedimentation tank as described in any one of claims 1 to 5.

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