A liquid line detection device and method for mud layer interface in settling tank

Abstract

This invention provides a liquid line detection device and method for a sedimentation tank sludge layer interface, relating to the field of alumina production technology. The device includes a control cabinet, a lifting mechanism, a fiber optic cable turntable, a fiber optic cable, a fixing device including guide wheels, and a composite photoelectric probe. The lifting mechanism drives the composite photoelectric probe to perform multi-depth scanning within the sedimentation tank, while a rotating rod drives the fiber optic cable turntable to rotate synchronously, achieving automatic extension and retraction of the fiber optic cable. The fiber optic cable transmits the signals collected by the composite photoelectric probe to the control cabinet, which calculates the actual transmittance based on the signals. This invention, through a dual-optical-path adaptive calibration design of the composite photoelectric probe combined with the actual transmittance calculation method, effectively eliminates system errors, ensuring that the final output transmittance value is only related to the slurry concentration, greatly improving the detection accuracy and repeatability of the clear liquid layer, turbid liquid layer, and sludge layer interface positions.

Description

Technical Field

[0001] This invention relates to the field of alumina production technology, and in particular to a liquid line detection device and method for a sedimentation tank sludge layer interface instrument. Background Technology

[0002] In alumina production, the settling tank is the core equipment for red mud separation and washing. The height of the mud layer interface inside the tank directly determines the clarity of the overflow and the concentration of the underflow, making it a key parameter for controlling production indicators. If the mud layer is too high, the overflow will become turbid, resulting in the loss of useful components; if the mud layer is too low, the underflow concentration will be insufficient, increasing the burden on subsequent filtration. Therefore, achieving accurate and stable detection of the mud layer interface is crucial.

[0003] Currently, the technologies used in the industry for detecting mud interfaces are mainly divided into several categories: First, the traditional manual probe or hammer method, but this method is labor-intensive, has high safety risks, and cannot achieve continuous online monitoring. Second, mechanical floats or hydrostatic instruments, but alumina slurry has the characteristics of high temperature, high alkali, and easy scaling, and the float surface is prone to scaling and failure, and the hydrostatic pressure tapping pipe often fails to work properly due to scaling and blockage. Third, ultrasonic or X-ray instruments, due to the strong attenuation of signals by high-concentration slurry, this method has poor measurement stability, and the management of radiation sources is complicated. In recent years, photoelectric or visual recognition technologies have emerged. Although they have achieved non-contact measurement, their optical windows still face the problem of image blurring and detection failure due to scaling and contamination under harsh working conditions.

[0004] Therefore, existing detection technologies cannot reliably solve the problems of sensor corrosion, scaling, and signal attenuation in the long term, and there is an urgent need for a new detection solution that can adapt to the complex working conditions of alumina settling tanks. Summary of the Invention

[0005] To meet the requirements for clarity of overflow from settling tanks and concentration of underflow during alumina production, this invention provides a settling tank mud layer interface meter liquid line detection device and detection method.

[0006] To achieve the above objectives, the main technical solution adopted by the present invention is as follows: In a first aspect of the present invention, a liquid line detection device for a sedimentation tank mud layer interface instrument is provided, comprising a control cabinet, a lifting mechanism, a fiber optic cable turntable, a fiber optic cable, a fixing device including a guide wheel, and a composite photoelectric probe disposed within the device. The control cabinet is electrically connected to the lifting mechanism. The lifting mechanism is rotatably connected to the fiber optic cable turntable via a rotating rod. The fiber optic cable is wound on the fiber optic cable turntable, with one end connected to the composite photoelectric probe via a fixing device including a guide wheel, and the other end connected to the control cabinet. The lifting mechanism drives the composite photoelectric probe to move along the depth direction of the settling tank and collect signals through the control cabinet. At the same time, the optical fiber cable turntable is driven to rotate synchronously through the rotating rod. The optical fiber cable transmits the signals collected by the composite photoelectric probe to the control cabinet to obtain the actual light transmittance.

[0007] Preferably, the composite photoelectric probe includes a housing, and the housing integrates an LED light source, a beam splitter, a measurement optical path, and a reference optical path; The LED light source is located inside the composite photoelectric probe; The beam splitter is installed in the output light path of the LED light source to split the light emitted by the LED light source into two parts: one entering the measurement light path and the other entering the reference light path. The measurement optical path includes a transmitting window, a receiving window, and a measurement light receiving end. The transmitting window and the receiving window are disposed on the side wall of the housing, and the measurement light receiving end is disposed inside the housing. The measurement light is emitted from the outside of the housing through the transmitting window and penetrates the slurry to be measured. After passing through the receiving window, the light enters the inside of the housing and is received by the measurement light receiving end to generate a measurement light signal. The reference optical path includes a reference light receiver, which is a closed optical path channel set inside the housing and isolated from the external slurry. The reference light is transmitted along the reference optical path and received by the reference light receiver to generate a reference light signal.

[0008] Preferably, the control cabinet has a built-in PLC, which is used to calculate the actual transmittance based on the ratio of the measured optical signal to the reference optical signal.

[0009] Preferably, the composite photoelectric probe further includes a temperature sensor disposed inside the composite photoelectric probe, used to monitor the temperature inside the composite photoelectric probe in real time and transmit the temperature signal to the PLC for temperature compensation of the measured optical signal.

[0010] Preferably, the lifting mechanism includes an explosion-proof motor, a reducer, and a photoelectric encoder; The reducer is connected to the explosion-proof motor, and the photoelectric encoder is rotatably connected to the explosion-proof motor and the reducer. The control cabinet controls the speed of the explosion-proof motor and the reducer, and feeds back the speed data and position data of the motor to the PLC through the photoelectric encoder. At the same time, the lifting distance of the lifting mechanism is obtained based on the position data.

[0011] Preferably, it also includes a cleaning chamber disposed within the device and electrically connected to the control cabinet; After the composite photoelectric probe completes the test, the lifting mechanism raises the composite photoelectric probe to the cleaning chamber through the control cabinet for hot water rinsing, acid pickling and soaking, clean water rinsing and compressed air blowing.

[0012] Preferably, it also includes a rain cover for the equipment, a display screen, a host computer, and a power distribution cabinet; The rainproof cover of the device covers the top of the device, the display screen and the host computer are mounted on the fixed structure of the device and electrically connected to the control cabinet, and the power distribution cabinet is located inside the device and supplies power to the device.

[0013] In another aspect of the present invention, a method for detecting the liquid line of a sedimentation tank sludge interface instrument is provided. This method, applied to the liquid line detection device of the sedimentation tank sludge interface instrument, includes the following steps: S1. PLC controls the lifting mechanism to drive the composite photoelectric probe to descend along the depth direction of the settling tank, and collects transmittance data and photoelectric encoder data in real time. S2. Determine the real-time descent depth of the composite photoelectric probe based on the photoelectric encoder data, and correlate it with the transmittance data at the corresponding time to construct a depth-transmittance curve; S3. Perform smoothing filtering on the depth-transmittance curve, calculate the first and second derivatives of the processed curve, and determine the location of the slurry stratification interface in the settling tank based on the gradient characteristics of transmittance as a function of depth and the abrupt change point where the first derivative reaches its maximum value and the second derivative changes from positive to negative. S4. Based on the location of the layered interface and combined with the historical depth data of the photoelectric encoder, the height of the clear liquid layer and the height of the mud layer are obtained. S5. After the test is completed, the lifting mechanism reverses and drives the composite photoelectric probe to rise until it enters the cleaning chamber and triggers the upper limit switch, thus completing the return of the composite photoelectric probe to its original position.

[0014] Preferably, in step S1, during the movement of the composite photoelectric probe along the depth direction of the settling tank, a variable-speed scanning method is adopted, specifically including the following steps: The interface regions of slurry stratification within the settling tank were determined based on historical testing data. Within the interface area, the composite photoelectric probe is controlled to move at a first speed, and within the non-interface area, it is controlled to move at a second speed higher than the first speed, so as to improve the overall detection efficiency while ensuring the accuracy of interface detection.

[0015] Preferably, it also includes intelligent cleaning of the composite photoelectric probe, specifically including the following steps: Set the detection cycle; After one of the aforementioned detection cycles is completed, the composite photoelectric probe is lifted into the cleaning chamber and a cleaning process is performed; During or after the detection process, the contamination status of the probe is determined based on the detection signal of the reference optical path in the composite photoelectric probe. When the reference optical signal is lower than a preset threshold, the cleaning process is triggered.

[0016] The beneficial effects of this invention are: 1. This invention employs a dual-optical-path adaptive calibration design with a composite photoelectric probe, combined with the calculation method of actual transmittance = measurement optical path signal / reference optical path signal, and real-time temperature compensation from a temperature sensor. This effectively eliminates systematic errors such as LED light source aging, temperature drift, and slight contamination of the viewing window, ensuring that the final output transmittance value is only related to the slurry concentration. This greatly improves the detection accuracy and repeatability of the interface positions of the clear liquid layer, turbid liquid layer, and mud layer.

[0017] 2. This invention achieves closed-loop control through a lifting mechanism equipped with a photoelectric encoder. Combined with the automatic cable winding and unwinding of the fiber optic cable turntable linked to the rotating rod, it can precisely control the composite photoelectric probe to perform multi-depth positioning scanning or continuous scanning in the settling tank. It can completely obtain the light transmittance profile of the slurry at different depths, accurately determine the height of each interface, and generate trend curves in real time, providing reliable data for process optimization.

[0018] 3. This invention integrates a multi-stage automatic cleaning process, including hot water rinsing, acid pickling and soaking, clean water rinsing and compressed air purging, by setting an openable cleaning chamber. The process is automatically controlled by a PLC. After scanning, the composite photoelectric probe is automatically lifted into the cleaning chamber for cleaning, effectively removing scale and dirt from the probe window surface, greatly reducing the number of manual maintenance operations, and making it suitable for long-term continuous operation in industrial sites. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the connection structure of a liquid line detection device for a sedimentation tank mud layer interface instrument according to the present invention.

[0020] The attached figures are labeled as follows: 1-Rain cover, 10-Cleaning chamber, 2-Host computer, 3-Control cabinet, 4-Power distribution cabinet, 5-Lifting mechanism, 6-Fiber optic cable turntable, 7-Fiber optic cable, 8-Fixing device, 9-Composite photoelectric probe. Detailed Implementation

[0021] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1As shown, this invention provides a liquid line detection device for a sedimentation tank sludge layer interface, including a control cabinet 3, a lifting mechanism 5, a fiber optic cable turntable 6, a fiber optic cable 7, a fixing device 8 including guide wheels, and a composite photoelectric probe 9. The device has a corrosion-resistant overall structure. The control cabinet 3 and the lifting mechanism 5 are connected via Modbus protocol to transmit control and feedback signals. The lifting mechanism 5 forms a rotational connection with the fiber optic cable turntable 6 through a rotating rod, establishing a synchronous linkage mechanism between the lifting and rotational movements. The fiber optic cable 7 is wound around the outer periphery of the fiber optic cable turntable 6. One end of the cable is connected to the composite photoelectric probe 9 via the fixing device 8 including guide wheels. The guide wheels limit the movement path of the fiber optic cable 7 and reduce bending stress and frictional resistance during movement. The other end is connected to the signal processing unit inside the control cabinet 3, thus forming a continuous signal transmission channel from the probe to the control system. The composite photoelectric probe 9 is suspended below the lifting mechanism 5 and reciprocates along the vertical direction of the settling trough under the drive of the lifting mechanism 5. The fiber optic cable turntable 6 rotates synchronously with the lifting mechanism 5 under the drive of the rotating rod, realizing the coordination between the extension and retraction of the fiber optic cable 7 and the displacement of the probe, avoiding cable slack or excessive stretching, and forming an integrated structure system of mechanical transmission and signal transmission.

[0023] During operation, control cabinet 3 outputs control signals to drive lifting mechanism 5, which in turn moves composite photoelectric probe 9 continuously along the depth direction of the settling tank. The probe performs optical detection on the slurry at different depths and generates corresponding photoelectric signals. These signals are transmitted to control cabinet 3 in real time via fiber optic cable 7. During transmission, the excellent anti-electromagnetic interference performance of optical fiber effectively ensures signal stability and accuracy. Simultaneously, the movement of lifting mechanism 5 synchronously drives the fiber optic cable turntable 6 to rotate via a rotating rod, allowing the fiber optic cable 7 to be smoothly released when the probe descends and orderly retracted when the probe rises. This avoids cable tangling, knotting, or fatigue damage, ensuring long-term operational reliability. Through the synergistic effect of the above structure and operating method, continuous detection by composite photoelectric probe 9 at different depths in the settling tank is achieved, and the collected photoelectric signals are converted into actual transmittance data, providing a reliable basis for the accurate identification of the clear liquid layer, turbid liquid layer, and mud layer interface. This structure not only improves the stability and repeatability of the detection process but also effectively extends the service life of the fiber optic cable and probe, reduces maintenance frequency, and possesses good industrial adaptability and application value.

[0024] In this embodiment, the composite photoelectric probe 9 includes a high-temperature resistant and corrosion-resistant titanium alloy housing. An LED light source, a beam splitter, a measurement optical path, and a reference optical path are integrated within the housing, forming a compact, integrated structure. The LED light source is installed inside the housing and serves as the light-emitting unit. A beam splitter is positioned on its outgoing optical path, corresponding to the optical axis of the LED light source, to separate the emitted light beam. The light separated by the beam splitter enters the measurement optical path and the reference optical path, respectively. The measurement optical path consists of a transmitting window, a receiving window, and a measurement light receiving end. The transmitting and receiving windows are embedded in the side wall of the housing and spaced apart from each other, using a high-transmittance, corrosion-resistant material to realize the light emission and recovery paths. The measurement light receiving end is located inside the housing and is correspondingly connected to the receiving window on the optical path. The reference optical path is located inside the housing, forming a closed channel isolated from the external environment. A reference light receiving end is located at its end to receive the reference light signal separated by the beam splitter. Through the above structural layout, a stable optical connection is formed between the LED light source, beam splitter, measurement optical path and reference optical path, and a dual-channel optical detection system is constructed in a limited space.

[0025] During operation, the LED light source emits a stable beam, which is separated into two parts by a beam splitter. The light entering the measurement optical path exits the housing through the emission window and enters the slurry to be tested. During propagation, it is attenuated by factors such as particle concentration and turbidity in the slurry. It then returns to the housing through the receiving window and is received by the measurement light receiver, thus forming a measurement optical signal reflecting the light transmittance characteristics of the slurry. The light entering the reference optical path propagates within a closed channel, without contact with the external slurry, and is ultimately received by the reference light receiver, forming a stable reference optical signal. By comparing the measurement optical signal and the reference optical signal, the influence of factors such as LED light source intensity fluctuations, temperature changes, and slight contamination of the window can be effectively eliminated, making the output results more stable and reliable. This dual-optical-path structure enables real-time self-calibration of the light source state, making the detection results mainly dependent on the optical properties of the slurry itself, thereby significantly improving the accuracy and repeatability of transmittance measurement, while enhancing the stability and anti-interference capability of the probe under complex operating conditions over long periods.

[0026] In this embodiment, the control cabinet 3 integrates a PLC, a power module, a signal isolator, and a transmitter. These units form an integrated electrical and signal connection structure within the control cabinet. The power module provides a stable power supply to the PLC, signal isolator, and transmitter, and converts and distributes external input power. The signal isolator connects to the measurement optical signal and reference optical signal acquired by the external composite photoelectric probe, respectively, to provide electrical isolation and anti-interference processing for the input signal, suppressing the impact of electromagnetic interference in the industrial environment on signal transmission. The transmitter connects to the output of the signal isolator to condition, amplify, or standardize the photoelectric signal to meet the signal requirements of the PLC input interface. The PLC, as the core control unit, establishes data and control connections with the power module, signal isolator, and transmitter, thus forming a complete signal acquisition and processing link.

[0027] During operation, the measurement and reference optical signals output by the composite photoelectric probe are first isolated by a signal isolator to ensure signal stability and security. They are then converted by a transmitter into a standard signal format compatible with PLC acquisition and input into the PLC. The PLC processes the received two signals, calculating the ratio of the measurement and reference optical signals to obtain the actual transmittance data reflecting the slurry's light transmission characteristics, thus eliminating the influence of factors such as light source fluctuations, temperature changes, and system drift. This calculation relationship can be expressed as: ; in, Indicates the actual light transmittance. Indicates the measurement of optical signals, This represents the reference optical signal. This processing method ensures that the final output is only related to the optical properties of the slurry itself, thus significantly improving detection accuracy and long-term stability. Simultaneously, the various functional units within the control cabinet work collaboratively to achieve a complete closed-loop processing flow of the signal from acquisition, isolation, conditioning to calculation and output. This not only enhances the system's anti-interference capability but also improves the reliability of continuous operation in complex industrial environments, reducing the risk of misjudgment due to signal fluctuations.

[0028] In this embodiment, the composite photoelectric probe 9 further integrates a temperature sensor and a viewing window assembly on the basis of the existing optical detection structure. The temperature sensor is arranged inside the probe housing, forming a spatially coordinated configuration with the LED light source, beam splitter, and measurement and reference optical paths to reflect the actual thermal environment inside the probe. The viewing window assembly is installed on the side wall of the housing corresponding to the measurement optical path, forming an optical channel structure with the transmitting and receiving windows to realize the emission and recovery of the light beam, while also providing sealing and protection for the optical components inside the housing. The temperature sensor is connected to the photoelectric signal transmission path through internal circuitry and establishes a signal transmission relationship with the PLC in the control cabinet 3, enabling the temperature signal to be transmitted synchronously with the measurement and reference optical signals. The viewing window assembly and the housing form a sealed fit, ensuring high light transmittance while maintaining the airtightness and corrosion resistance of the overall probe structure, thus forming a structural system integrating optical detection, temperature monitoring, and environmental isolation.

[0029] During operation, the temperature sensor continuously monitors the internal temperature of the composite photoelectric probe 9 in real time and transmits the temperature signal to the PLC for data processing. Since the light-emitting characteristics, photoelectric receiving response, and optical channel transmittance all drift with temperature changes, the PLC compensates and corrects the measured light signal based on the collected temperature signal, thereby reducing the impact of temperature on the transmittance calculation results. Simultaneously, the viewing window assembly effectively isolates the external slurry from the internal optical system while ensuring efficient light transmission, reducing the impact of corrosive media and impurities on the stability of the optical path and mitigating the interference of adhering contaminants on detection accuracy to a certain extent. Through the synergistic effect of the temperature compensation mechanism and the stable optical channel, the measurement results more accurately reflect the optical characteristics of the slurry, significantly improving detection accuracy and long-term stability, while enhancing the equipment's adaptability and reliable operation in complex industrial environments such as high temperatures and strong corrosion.

[0030] In this embodiment, the lifting mechanism 5 includes an explosion-proof motor, a reducer, and a photoelectric encoder. The explosion-proof motor, as a power output unit, is connected to the reducer. The reducer reduces the output speed of the explosion-proof motor and increases its output torque, thereby meeting the drive requirements for the stable lifting of the composite photoelectric probe 9 within the settling tank. The photoelectric encoder establishes a linkage relationship with the output shaft of the explosion-proof motor or reducer to detect displacement changes during rotation in real time and convert the rotation information into an electrical signal output. The control cabinet 3 forms an electrical connection with the explosion-proof motor, reducer, and photoelectric encoder. The control circuit adjusts the operating state of the explosion-proof motor and simultaneously receives speed and position signals from the photoelectric encoder, thus forming a closed-loop control structure integrating drive and feedback, enabling the lifting mechanism 5 to coordinate between mechanical transmission and electrical control.

[0031] During operation, control cabinet 3 outputs control signals to drive the explosion-proof motor. The motor, after transmitting power through a reducer, propels the composite photoelectric probe 9 to move smoothly up and down along the depth direction of the settling tank. The reducer ensures smoother output motion and higher positioning accuracy. The photoelectric encoder synchronously collects speed changes and rotational position information during motor or reducer rotation and feeds the corresponding signals back to the PLC. The PLC performs real-time calculations based on this feedback data, converting the rotational displacement into the actual displacement of the lifting mechanism 5, thereby obtaining the specific depth position of the composite photoelectric probe 9 in the settling tank. By adjusting the motor speed and providing real-time feedback of position data, precise control of the probe's movement speed and trajectory can be achieved, improving the stability and repeatability of the detection process. This structure, by introducing an coded feedback mechanism, transforms the lifting process from open-loop control to closed-loop control, not only improving positioning accuracy but also effectively avoiding error accumulation caused by slippage or load changes, enhancing the system's reliability and safety under complex working conditions, while meeting the requirements for use in explosion-proof environments.

[0032] In this embodiment, a cleaning chamber 10 is installed inside the device. The cleaning chamber 10 and the control cabinet 3 establish a communication connection via the Modbus protocol to achieve centralized control and status feedback of the cleaning process. The cleaning chamber 10 has an openable and closable structure. Its outer shell forms a closed space, and the inner lining is made of acid and alkali corrosion resistant material to adapt to the highly corrosive media environment that may exist in the settling tank. The cleaning chamber 10 integrates hot water nozzles, acid cleaning nozzles, clean water nozzles, compressed air nozzles, and a brushing device. Each spraying unit is connected to the corresponding media supply system to deliver cleaning media such as hot water, acid, clean water, and compressed air, and the opening and closing are achieved by electromagnetic control. The composite photoelectric probe 9 can enter the internal space of the cleaning chamber 10 under the drive of the lifting mechanism 5, so that the cleaning chamber 10, the lifting mechanism 5, and the composite photoelectric probe 9 form a cooperative relationship in structure, thereby constructing a structural system that can perform encapsulation cleaning of the probe.

[0033] During operation, after the composite photoelectric probe 9 completes depth scanning within the settling tank, the PLC sends a control command to the lifting mechanism 5, causing it to drive the composite photoelectric probe 9 upwards and into the cleaning chamber 10. The cleaning chamber 10 then closes, creating a relatively sealed cleaning environment. Under the control of the PLC, various nozzles are activated sequentially or in combination according to a preset program, performing a multi-stage cleaning process including hot water rinsing, acid pickling and soaking, clean water rinsing, and compressed air purging. Hot water removes loose deposits from the probe surface, acid pickling dissolves stubborn scale and inorganic deposits, clean water rinses and neutralizes residual acid, compressed air quickly dries the probe surface and removes residual liquid, and a brushing device provides auxiliary mechanical cleaning to enhance the cleaning effect. Through this multi-stage coordinated cleaning method, contaminants and scale on the surface of the transmitting and receiving windows of the composite photoelectric probe 9 can be effectively removed, restoring its light transmission performance and avoiding light signal attenuation and measurement errors caused by contamination. Based on this working method, the device has the ability to automatically clean itself online, which significantly reduces the frequency of manual maintenance, improves the stability and detection accuracy of long-term operation, and ensures the reliability and consistency of mud interface detection results.

[0034] In this embodiment, the device also includes a rain cover 1, a display screen and host computer 2, and a power distribution cabinet 4. The rain cover 1 is located on the top of the device and forms a covering relationship with the main body, providing external protection for the internal functional units. The display screen and host computer 2 are mounted on the device frame and rigidly connected to the frame by welding, ensuring structural stability and vibration resistance in industrial operating environments. The display screen and host computer 2 establish a communication connection with the control cabinet 3 via a network cable, enabling them to receive and interact with data processed by the PLC in the control cabinet 3. The power distribution cabinet 4 is located inside the device and forms an electrical connection with the control cabinet 3 and each power-consuming unit, providing a unified power input to the system. Through the above structural arrangement, the rain cover 1, display screen and host computer 2, and power distribution cabinet 4 cooperate with the control cabinet 3 and other modules in terms of structural protection, data interaction, and power supply, respectively, thus constructing a complete external support system.

[0035] During operation, the rain cover 1 shields the top of the device, effectively preventing rainwater, splashing liquids, and external impurities from entering the device, thereby reducing the adverse effects of the external environment on electrical components and mechanical structures, and improving the safety and reliability of system operation. The display screen and the host computer 2 communicate in real time with the control cabinet 3 via network cable, receiving and displaying the detection data processed by the PLC. This allows operators to intuitively obtain the changes in light transmittance and interface distribution at different depths within the settling tank, while also enabling parameter setting and operation monitoring, thus achieving human-machine interaction. The power distribution cabinet 4 provides a stable power supply to each functional unit of the device, ensuring the continuous operation of the control system, actuators, and detection modules. Through the above operating methods, the device possesses excellent protective performance, stable power supply capabilities, and reliable data display and interaction capabilities in complex industrial environments, thereby improving the overall system's operational stability, ease of operation, and engineering application value.

[0036] Furthermore, this invention also provides a method for detecting the liquid line in a sedimentation tank sludge layer interface instrument, applied to the aforementioned detection device. This method is based on an intelligent interface recognition algorithm and an intelligent cleaning method, wherein the intelligent interface recognition algorithm employs an algorithm based on the actual transmittance oblique line abrupt change point. The method includes the following steps: First, the lifting mechanism 5 is controlled by PLC to control the descent of the composite photoelectric probe 9. A variable speed detection method is adopted. Based on historical data, the boundary areas of the clear liquid layer, turbid liquid layer and mud layer are defined with a threshold of ±0.5m. Within the boundary area, the composite photoelectric probe 9 is controlled to descend at a speed of 0.02m / s, and in other areas, it is descended at 0.2m / s, balancing the overall process detection speed and the accuracy of the boundary layer. During the descent of the composite photoelectric probe 9, the system collects photoelectric encoder and transmittance data every 10ms. The photoelectric encoder data is further processed to obtain the descent depth of the composite photoelectric probe 9, and a depth-transmittance curve is plotted. After smoothing and filtering the curve, the first and second derivatives of the curve are obtained. The boundary points of the clear liquid layer, turbid liquid layer, and mud layer are obtained by targeting the two points where the first derivative is at its maximum and the second derivative changes from positive to negative during the descent of the composite photoelectric probe 9. Then, the height of the clear liquid layer and the height of the mud layer are calculated by using the historical data of the photoelectric encoder. After the detection is completed, the lifting mechanism 5 reverses and drives the composite photoelectric probe 9 to rise at a constant speed from the mud layer position in the settling tank. After the composite photoelectric probe 9 leaves the liquid surface, it continues to rise until it enters the top cleaning chamber 10 and triggers the upper limit switch, completing the lifting and return.

[0037] The method also includes intelligent cleaning of the composite photoelectric probe 9, specifically including the following steps: A fixed cleaning cycle of 5 times is set. After one testing cycle, control cabinet 3 executes the following cleaning procedure: First, the bottom sealing door of cleaning chamber 10 is closed to form a sealed space. Control cabinet 3 opens the hot water solenoid valve and sprays hot water through the high-pressure nozzle onto the viewing window of composite photoelectric probe 9 for 15 to 30 seconds to wash away most of the alkaline solution and loose mud adhering to the surface of composite photoelectric probe 9. After the first-stage rinsing, the acid washing solenoid valve is opened to spray dilute acid solution onto the surface of composite photoelectric probe 9 and soak it for 30 to 60 seconds to fully dissolve the aluminosilicate scale. After acid washing, the clean water solenoid valve is opened for a second-stage rinsing to thoroughly remove residual acid. Finally, the compressed air solenoid valve is opened to blow high-pressure air to dry the surface of composite photoelectric probe 9, especially the viewing window glass assembly, to prevent water stains from affecting the transmittance of subsequent tests. After cleaning, the sealing door of cleaning chamber 10 is opened, and composite photoelectric probe 9 stands by in cleaning chamber 10, waiting for the next testing cycle. At the same time, based on real-time data from the reference optical path, the cleaning process is automatically triggered if the return transmittance of the reference optical path is lower than the threshold.

[0038] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A liquid line detection device for a sedimentation tank mud layer interface, characterized in that, This includes a control cabinet, lifting mechanism, fiber optic cable turntable, fiber optic cable, fixing device including guide wheels, and composite photoelectric probe installed within the device; The control cabinet is electrically connected to the lifting mechanism. The lifting mechanism is rotatably connected to the fiber optic cable turntable via a rotating rod. The fiber optic cable is wound on the fiber optic cable turntable, with one end connected to the composite photoelectric probe via a fixing device including a guide wheel, and the other end connected to the control cabinet. The lifting mechanism drives the composite photoelectric probe to move along the depth direction of the settling tank and collect signals through the control cabinet. At the same time, the optical fiber cable turntable is driven to rotate synchronously through the rotating rod. The optical fiber cable transmits the signals collected by the composite photoelectric probe to the control cabinet to obtain the actual light transmittance.

2. The liquid line detection device for a sedimentation tank mud layer interface instrument as described in claim 1, characterized in that, The composite photoelectric probe includes a housing, which integrates an LED light source, a beam splitter, a measurement optical path, and a reference optical path. The LED light source is located inside the composite photoelectric probe; The beam splitter is installed in the output light path of the LED light source to split the light emitted by the LED light source into two parts: one entering the measurement light path and the other entering the reference light path. The measurement optical path includes a transmitting window, a receiving window, and a measurement light receiving end. The transmitting window and the receiving window are disposed on the side wall of the housing, and the measurement light receiving end is disposed inside the housing. The measurement light is emitted from the outside of the housing through the transmitting window and penetrates the slurry to be measured. After passing through the receiving window, the light enters the inside of the housing and is received by the measurement light receiving end to generate a measurement light signal. The reference optical path includes a reference light receiver, which is a closed optical path channel set inside the housing and isolated from the external slurry. The reference light is transmitted along the reference optical path and received by the reference light receiver to generate a reference light signal.

3. The liquid line detection device for a sedimentation tank mud layer interface instrument as described in claim 2, characterized in that, The control cabinet has a built-in PLC, which is used to calculate the actual transmittance based on the ratio of the measured optical signal to the reference optical signal.

4. The liquid line detection device for a sedimentation tank mud layer interface instrument as described in claim 3, characterized in that, The composite photoelectric probe also includes a temperature sensor installed inside the composite photoelectric probe, which is used to monitor the temperature inside the composite photoelectric probe in real time and transmit the temperature signal to the PLC to perform temperature compensation on the measured optical signal.

5. The liquid line detection device for a sedimentation tank mud layer interface instrument as described in claim 3, characterized in that, The lifting mechanism includes an explosion-proof motor, a reducer, and a photoelectric encoder; The reducer is connected to the explosion-proof motor, and the photoelectric encoder is rotatably connected to the explosion-proof motor and the reducer. The control cabinet controls the speed of the explosion-proof motor and the reducer, and feeds back the speed data and position data of the motor to the PLC through the photoelectric encoder. At the same time, the lifting distance of the lifting mechanism is obtained based on the position data.

6. The liquid line detection device for a sedimentation tank mud layer interface instrument as described in claim 1, characterized in that, It also includes a cleaning chamber installed inside the device and electrically connected to the control cabinet; After the composite photoelectric probe completes the test, the lifting mechanism raises the composite photoelectric probe to the cleaning chamber through the control cabinet for hot water rinsing, acid pickling and soaking, clean water rinsing and compressed air blowing.

7. The liquid line detection device for a sedimentation tank mud layer interface instrument as described in claim 1, characterized in that, It also includes equipment rain covers, displays, host computers, and power distribution cabinets; The rainproof cover of the device covers the top of the device, the display screen and the host computer are mounted on the fixed structure of the device and electrically connected to the control cabinet, and the power distribution cabinet is located inside the device and supplies power to the device.

8. A method for detecting the liquid line in a sedimentation tank using a mud interface instrument, characterized in that, This method, applied to the liquid line detection device of the sedimentation tank mud layer interface instrument according to any one of claims 1 to 7, includes the following steps: S1. PLC controls the lifting mechanism to drive the composite photoelectric probe to descend along the depth direction of the settling tank, and collects transmittance data and photoelectric encoder data in real time. S2. Determine the real-time descent depth of the composite photoelectric probe based on the photoelectric encoder data, and correlate it with the transmittance data at the corresponding time to construct a depth-transmittance curve; S3. Perform smoothing filtering on the depth-transmittance curve, calculate the first and second derivatives of the processed curve, and determine the location of the slurry stratification interface in the settling tank based on the gradient characteristics of transmittance as a function of depth and the abrupt change point where the first derivative reaches its maximum value and the second derivative changes from positive to negative. S4. Based on the location of the layered interface and combined with the historical depth data of the photoelectric encoder, the height of the clear liquid layer and the height of the mud layer are obtained. S5. After the test is completed, the lifting mechanism reverses and drives the composite photoelectric probe to rise until it enters the cleaning chamber and triggers the upper limit switch, thus completing the return of the composite photoelectric probe to its original position.

9. The method for detecting the liquid line in a sedimentation tank mud layer interface instrument as described in claim 8, characterized in that, In S1, as the composite photoelectric probe moves along the depth direction of the settling tank, a variable-speed scanning method is used, specifically including the following steps: The interface regions of slurry stratification within the settling tank were determined based on historical testing data. Within the interface area, the composite photoelectric probe is controlled to move at a first speed, and within the non-interface area, it is controlled to move at a second speed higher than the first speed, so as to improve the overall detection efficiency while ensuring the accuracy of interface detection.

10. The method for detecting the liquid line in a sedimentation tank mud layer interface instrument as described in claim 8, characterized in that, It also includes intelligent cleaning of composite photoelectric probes, specifically comprising the following steps: Set the detection cycle; After one of the aforementioned detection cycles is completed, the composite photoelectric probe is lifted into the cleaning chamber and a cleaning process is performed; During or after the detection process, the contamination status of the probe is determined based on the detection signal of the reference optical path in the composite photoelectric probe. When the reference optical signal is lower than a preset threshold, the cleaning process is triggered.

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