Method and device for determining interface position of aluminum electrolysis cell and aluminum electrolysis cell system

Abstract

The invention discloses a method and device for determining the interface position of an aluminum electrolysis cell and an aluminum electrolysis cell system, and relates to the field of aluminum electrolysis cell liquid level monitoring. A control module in the device controls the insertion end of a probe to advance from a preset starting position to the interior of the aluminum electrolysis cell through a driving module; in the advancing process, a measured resistance value obtained at the current moment is obtained, and the advanced depth and a preset filtering algorithm are combined to determine the corrected advanced depth and the corrected resistance value at the current moment; according to the corrected resistance value and a preset interlayer switching change strategy, determining the corrected advanced depth as a target interface position corresponding to the current interlayer switching when it is judged that the insertion end of the probe is advanced to the interface of the current interlayer switching at the current moment; and the target interface position during switching of different layers in the aluminum electrolysis cell is determined along with the propelling process. According to the scheme, the position of the target interface is reliably determined when different layers are switched in the one-time propelling process through the probe, and the efficiency and the interface position determining precision are higher.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum electrolysis cell liquid level monitoring, in particular to an aluminum electrolysis cell interface position determination method and device and an aluminum electrolysis cell system. BACKGROUND

[0002] In the interior of the aluminum electrolysis cell, the upper layer is electrolyte, the middle layer is aluminum liquid, and the lower layer is cathode. Accurately determining the interface position when switching between different layers helps to determine the liquid level height of different layers and ensure the stable progress of the electrolysis process. For this purpose, there are currently three ways. The first way is to measure the static pressure of the electrolyte and aluminum liquid in the electrolysis cell by installing pressure sensors and calculate the liquid surface position by using the pressure difference. The core principle is to calculate the liquid level by the static pressure difference of different liquid layers. However, this method is easily disturbed by the high temperature and strong electromagnetic field inside the electrolysis cell, resulting in pressure signal drift. Moreover, for switching between different layers, such as electrolyte-aluminum liquid and aluminum liquid-cathode double interface, pressure sensors need to be installed correspondingly to measure. It is impossible to obtain the interface position when switching between different layers by one measurement. The second way is to use the difference in the propagation speed of ultrasonic waves in different media to determine the interface position by emitting ultrasonic waves and receiving the time difference of reflected signals. However, in this way, the ultrasonic wave attenuates severely when propagating in the high-temperature gas above the electrolyte in the aluminum electrolysis cell, and the signal-to-noise ratio is low. Moreover, the oxidation film on the surface of the aluminum liquid will interfere with the reflected signal, resulting in an identification error of the interface between different layers, which can reach ±5mm or more. The third way is to use radar technology to emit electromagnetic waves and analyze the reflected signals to determine the interface position and then obtain the liquid level height by the time domain reflection principle. However, in this way, high-frequency electromagnetic waves are easily disturbed in a strong magnetic field environment, and additional shielding devices need to be installed. Moreover, the equipment cost is high, and a single system can cost more than 100,000 yuan, which is difficult to deploy on a large scale.

[0003] Therefore, how to provide a more effective technical solution to determine the interface position when switching between different layers in the aluminum electrolysis cell is a current problem to be solved. SUMMARY

[0004] Therefore, how to provide a more effective technical solution to determine the interface position when switching between different layers in the aluminum electrolysis cell is a current problem to be solved.

[0005] To solve the above technical problems, the application provides an aluminum electrolysis cell interface position determination method applied to a control module of an aluminum electrolysis cell interface position determination device, the aluminum electrolysis cell interface position determination device further comprising a driving module, a probe and a resistance measurement module, the control module, the driving module and the probe being connected in sequence, and the resistance measurement module being connected with the control module and the non-insertion end of the probe respectively, the aluminum electrolysis cell interface position determination method comprising:

[0006] controlling the insertion end of the probe to start advancing into the aluminum electrolysis cell from a preset starting position through the driving module;

[0007] acquiring a measured resistance value obtained by the resistance measurement module at the current time during the advancing process;

[0008] determining a corrected advanced depth and a corrected resistance value at the current time based on the advanced depth at the current time, the measured resistance value and a preset filtering algorithm;

[0009] judging whether the insertion end of the probe has advanced to the boundary of the current interlayer switching according to the corrected resistance value and a preset interlayer switching change strategy at the current time;

[0010] if yes, determining that the corrected advanced depth is the target interface position corresponding to the current interlayer switching, and determining the target interface position at different interlayer switchings in the aluminum electrolysis cell following the advancing process.

[0011] Further, the controlling the insertion end of the probe to start advancing into the aluminum electrolysis cell from a preset starting position through the driving module comprises:

[0012] controlling the insertion end of the probe to start advancing into the aluminum electrolysis cell from a preset starting position at a first preset speed through the driving module;

[0013] after determining the corrected advanced depth and the corrected resistance value at the current time based on the advanced depth at the current time, the measured resistance value and the preset filtering algorithm, the method further comprises:

[0014] determining a first resistance change rate according to the corrected resistance value at the current time, the corrected resistance value at the last time and a position change amount;

[0015] judging whether the first resistance change rate is greater than a first preset threshold;

[0016] if yes, controlling the insertion end of the probe to advance into the aluminum electrolysis cell at a second preset speed through the driving module, the second preset speed being less than the first preset speed.

[0017] Further, based on the measured resistance value and the advanced depth at the current time, and a preset filtering algorithm, a corrected advanced depth and a corrected resistance value at the current time are determined, including:

[0018] Based on the measured resistance value and the advanced depth at the current time, and the corrected resistance value and the corrected advanced depth at the previous time, a corrected advanced depth and a corrected resistance value at the current time are determined by using a Kalman filtering algorithm.

[0019] Further, when the interface of the current interlayer switching to be determined following the advancing process is the interface between air and electrolyte, whether the insertion end of the probe has advanced to the interface of the current interlayer switching at the current time is determined according to the corrected resistance value and a preset interlayer switching change strategy, including:

[0020] A second resistance change rate at the current time is determined according to a first preset relationship, and the first preset relationship is:

[0021]

[0022] Wherein, The second resistance change rate is represented by R k The corrected resistance value at the current time is represented by R k-1 The corrected resistance value at the previous time is represented by Δt, and the time difference is represented by Δt.

[0023] Whether the second resistance change rate is less than a second preset threshold is determined, and the second preset threshold is set based on the resistance mutation characteristics from the air to the electrolyte;

[0024] If yes, it is determined that the insertion end of the probe has advanced to the interface between the air and the electrolyte at the current time.

[0025] Further, when the interface of the current interlayer switching to be determined following the advancing process is the interface between the electrolyte and aluminum liquid, whether the insertion end of the probe has advanced to the interface of the current interlayer switching at the current time is determined according to the corrected resistance value and a preset interlayer switching change strategy, including:

[0026] The second resistance change rate at the current time is determined according to the first preset relationship;

[0027] A resistance change acceleration at the current time is determined according to a second preset relationship, and the second preset relationship is:

[0028]

[0029] Wherein, The resistance change acceleration is represented by (dR / dt) krepresents a second resistance change rate at the current time, (dR / dt) k-1 represents a second resistance change rate at the previous time;

[0030] determining whether the resistance change acceleration is greater than a third preset threshold value, the third preset threshold value being set based on a resistance mutation characteristic from the electrolyte to the aluminum liquid;

[0031] if yes, determining that the insertion end of the probe has advanced to the interface of the electrolyte and the aluminum liquid at the current time.

[0032] Further, when the interface of the current interlayer switching to be determined follows the advancing process, the insertion end of the probe is determined to have advanced to the interface of the current interlayer switching at the current time according to the corrected resistance value and a preset interlayer switching change strategy, comprising:

[0033] determining the second resistance change rate at the current time according to the first preset relationship, so as to determine the resistance change acceleration at the current time based on the second preset relationship;

[0034] determining whether the resistance change acceleration is less than a fourth preset threshold value, the fourth preset threshold value being set based on a resistance mutation characteristic from the aluminum liquid to the cathode;

[0035] if yes, determining that the insertion end of the probe has advanced to the interface of the aluminum liquid and the cathode at the current time.

[0036] To solve the above technical problems, the application further provides an aluminum electrolysis cell interface position determination device, comprising a control module, a driving module, a probe and a resistance measurement module;

[0037] The control module, the driving module and the probe are connected in sequence, and the resistance measurement module is connected with the control module and a non-insertion end of the probe respectively.

[0038] The control module is used to execute the steps of the aluminum electrolysis cell interface position determination method as described above.

[0039] Further, the resistance measurement module comprises an ohmmeter.

[0040] An output end of the ohmmeter is connected with the control module, a first detection end is connected with the non-insertion end of the probe, and a second detection end is connected with a cathode bus of the aluminum electrolysis cell.

[0041] Further, the driving module comprises a driving motor and a lead screw.

[0042] The control module, the driving motor, the lead screw and the non-insertion end of the probe are connected in sequence.

[0043] To solve the above technical problems, the application further provides an aluminum electrolysis cell system comprising an aluminum electrolysis cell, and further comprising the aluminum electrolysis cell interface position determination device as described above.

[0044] The application provides an aluminum electrolysis cell interface position determination method, device and system. In the device, a control module, a driving module and a probe are connected in sequence, and a resistance measurement module is connected with the control module and a non-insertion end of the probe. The insertion end of the probe is driven by the driving module to advance from a preset starting position to the interior of the aluminum electrolysis cell. During the advancement, a measured resistance value obtained by the resistance measurement module at the current time is acquired. Based on the advanced depth and the measured resistance value at the current time and a preset filtering algorithm, a corrected advanced depth and a corrected resistance value at the current time are determined to suppress electromagnetic noise and mechanical vibration interference. Whether the insertion end of the probe has advanced to the interface of the current interlayer switching is determined according to the corrected resistance value and a preset interlayer switching change strategy. If yes, the corrected advanced depth is determined as the target interface position corresponding to the current interlayer switching, until the target interface position at different interlayer switching in the aluminum electrolysis cell is determined following the advancement. It can be seen that the target interface position at different interlayer switching can be reliably determined in one advancement process by using the probe, which is more efficient. The interface position determination accuracy is higher by correcting the resistance value and the advanced depth, which is beneficial to application in the strong magnetic field environment of the aluminum electrolysis cell, has strong reliability and is beneficial to deployment, and is beneficial to practical application.

[0045] The above description is only a summary of the technical solutions of the application. In order to more clearly understand the technical means of the application, the application can be implemented according to the content of the specification. In order to make the above and other purposes, characteristics and advantages of the application more obvious and easy to understand, the specific embodiments of the application are described below. BRIEF DESCRIPTION OF DRAWINGS

[0046] The accompanying drawings described herein are used to provide further understanding of the application, and form a part of the application. The schematic embodiments of the application and their descriptions are used to explain the application, and do not constitute an improper limitation on the application. In the drawings:

[0047] Figure 1 A flowchart of an aluminum electrolysis cell interface position determination method provided by the application;

[0048] Figure 2 A structural schematic diagram of an aluminum electrolysis cell interface position determination device provided by the application. DETAILED DESCRIPTION

[0049] The core of the present application is to provide an aluminum electrolysis cell interface position determination method, device and aluminum electrolysis cell system, which can reliably realize the determination of the target interface position during the switching between different layers in one propulsion process by using a probe, and has higher efficiency and interface position determination accuracy.

[0050] The technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art belong to the scope of protection of the present application.

[0051] The terms "first", "second", and the like in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of a kind and do not limit the number of objects, for example, the first object can be one or more. In addition, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / ", generally indicates that the front and rear associated objects are in a "or" relationship.

[0052] Please refer to Figure 1 and Figure 2 , Figure 1 A flowchart of an aluminum electrolysis cell interface position determination method provided by the present application, Figure 2 A structural schematic diagram of an aluminum electrolysis cell interface position determination device provided by the present application.

[0053] The aluminum electrolysis cell interface position determination method is applied to a control module 1 in an aluminum electrolysis cell interface position determination device, and the aluminum electrolysis cell interface position determination device further comprises a driving module 2, a probe 3 and a resistance measurement module 4. The control module 1, the driving module 2 and the probe 3 are connected in sequence, and the resistance measurement module 4 is connected with the non-insertion end of the control module 1 and the probe 3 respectively. The aluminum electrolysis cell interface position determination method comprises the following steps:

[0054] S11: The insertion end of the probe 3 is controlled by the driving module 2 to start advancing from a preset starting position to the inside of the aluminum electrolysis cell;

[0055] S12: In the advancing process, the measured resistance value obtained by the resistance measurement module 4 at the current time is acquired;

[0056] S13: The corrected advanced depth and the corrected resistance value at the current time are determined based on the advanced depth and the measured resistance value at the current time, and a preset filtering algorithm;

[0057] S14: judging whether the insertion end of the probe 3 has advanced to the interface of the current interlayer switching according to the corrected resistance value and the preset interlayer switching change strategy; if yes, entering S15;

[0058] S15: determining that the corrected advanced depth is the target interface position corresponding to the current interlayer switching until the target interface positions at different interlayer switchings in the aluminum electrolytic cell are determined following the advancing process.

[0059] In the embodiment, the probe 3 can be an iron drill with high temperature and corrosion resistance, and the end of the probe 3 inserted into the aluminum electrolytic cell is the insertion end, and the other end is the non-insertion end; the output end of the driving module 2 is specifically connected with the non-insertion end of the probe 3, and the preset starting position can be a position above the aluminum electrolytic cell and separated from the electrolyte in the aluminum electrolytic cell by a certain distance. In the advancing process, the probe 3 will pass through air-electrolyte-aluminum liquid-cathode in turn, so there are three interface positions to be determined, which are the interface positions at air-electrolyte switching, electrolyte-aluminum liquid switching and aluminum liquid-cathode switching.

[0060] In Figure 2 the advancing direction of the probe 3 is indicated by a downward arrow, and in the advancing process, the resistance measuring module 4 can detect the measured resistance value in real time. Based on the fact that the resistance will change suddenly at different interlayer switchings, the measured resistance value is continuously obtained through step S12. Considering that mechanical vibration interference may be generated when the probe 3 is controlled to advance by the driving module 2, and the environment of the aluminum electrolytic cell itself is a strong electromagnetic field (>100 Gauss) environment, the filtering correction process is performed through step S13. Different determination methods are set in the preset interlayer switching change strategy for different interlayer switchings, so that when it is determined that the insertion end of the probe 3 has advanced to the interface of the current interlayer switching, it is determined that the corrected advanced depth is the target interface position corresponding to the current interlayer switching.

[0061] More specifically, after determining that the corrected advanced depth is the target interface position corresponding to the current interlayer switching, the interface of the current interlayer switching needs to be updated, for example, the interface of the current interlayer switching is the interface at air-electrolyte switching, and after completing the calibration of the target interface position corresponding thereto, the interface of the current interlayer switching can be updated to the interface at electrolyte-aluminum liquid switching, which is beneficial to determining whether the interface position at this time is reached through the determination method corresponding to the updated interface of the interlayer switching in the preset interlayer switching change strategy in the subsequent process, until the determination of the interface position at aluminum liquid-cathode switching is completed, it is determined that the target interface positions at different interlayer switchings in the aluminum electrolytic cell have been determined following the advancing process.

[0062] In addition, after the target interface positions in the different layer switching are determined, the actual liquid level height of the electrolyte, the actual liquid level height of the aluminum liquid, and the actual height of the cathode in the aluminum electrolysis cell can be determined according to the preset starting position and the target interface positions, for example, the target interface position corresponding to the air-electrolyte is a first distance from the preset starting position, the target interface position corresponding to the electrolyte-aluminum liquid is a second distance from the preset starting position, and the actual liquid level height of the electrolyte is the difference between the second distance and the first distance; the target interface position corresponding to the aluminum liquid-cathode is a third distance from the preset starting position, and the actual liquid level height of the aluminum liquid is the difference between the third distance and the second distance; and the fourth distance between the preset starting position and the bottom of the cathode (i.e., the bottom of the electrolysis cell) can be determined, and the actual height of the cathode is the difference between the fourth distance and the third distance. In addition, before the above steps are performed, a calibration program can be used for initialization to calibrate the reference resistance; and after the target interface position in the aluminum liquid-cathode switching is calibrated, the probe 3 can be controlled by the driving module 2 to exit the aluminum electrolysis cell, and specifically, the probe 3 can be controlled to return to the preset starting position.

[0063] In addition, the obtained target interface positions can be stored in the memory and sent to the upper monitoring module in communication connection with the control module 1, so that the interface calibration results can be intuitively displayed on the human-computer interaction module of the upper monitoring module, and the technical personnel can timely master the situation.

[0064] In summary, the aluminum electrolysis cell interface position determination method provided in the application can reliably determine the target interface positions in the different layer switching in one advancing process of the probe 3, has higher efficiency, and has higher interface position determination accuracy through the correction of the resistance value and the advanced depth, is suitable for application in the strong magnetic field environment of the aluminum electrolysis cell, has high reliability and is suitable for deployment, and is suitable for practical application.

[0065] Based on the above embodiments:

[0066] In some embodiments, the insertion end of the probe 3 is controlled by the driving module 2 to advance from the preset starting position to the inside of the aluminum electrolysis cell, including:

[0067] The insertion end of the probe 3 is controlled by the driving module 2 to advance from the preset starting position to the inside of the aluminum electrolysis cell at a first preset speed;

[0068] After the corrected advanced depth and the corrected resistance value at the current time are determined based on the advanced depth and the measured resistance value at the current time and the preset filtering algorithm, the method further includes:

[0069] A first resistance change rate is determined according to the corrected resistance value at the current time, the corrected resistance value at the previous time, and the position change amount;

[0070] determining whether the first resistance change rate is greater than a first preset threshold value;

[0071] If yes, the insertion end of the probe 3 is controlled by the driving module 2 to advance to the interior of the aluminum reduction cell at a second preset speed, which is less than the first preset speed.

[0072] Specifically, the first preset speed is essentially an initial constant speed. When the probe 3 approaches the interface of the current interlayer switching, the first resistance change rate will change from a value close to 0, so when the first resistance change rate is greater than the first preset threshold value, the probe 3 is controlled to advance at the second preset speed in the above manner, and the second preset speed is less than the first preset speed, which avoids missing the target interface position or causing inaccurate calibration of the target interface position while maintaining a high speed, achieving a balance between fast approach to the interface and fine advancement near the interface, and achieving adaptive control of the advancement speed. For example, the second preset speed can be 5 mm / s, and the first preset speed can be 2.5 mm / s, which can be flexibly set according to actual application requirements.

[0073] In addition, when the first resistance change rate is not greater than the first preset threshold value, the probe 3 can be maintained at the first preset speed; and the first preset threshold value can be flexibly set according to actual requirements, which is not particularly limited here. It should be noted that after the above-mentioned embodiment is implemented to update the interface of the current interlayer switching to be determined, the probe 3 can be controlled to advance at the first preset speed again to reach the new updated interlayer switching interface faster, and then advance at the second preset speed when approaching the updated interlayer switching interface.

[0074] In some embodiments, the corrected advanced depth and the corrected resistance value at the current time are determined based on the advanced depth and the measured resistance value at the current time, and a preset filtering algorithm, including:

[0075] The corrected advanced depth and the corrected resistance value at the current time are determined based on the measured resistance value and the advanced depth at the current time, and the corrected resistance value and the corrected advanced depth at the last time, using a Kalman filtering algorithm.

[0076] Specifically, the advanced depth and the resistance value are used as state vectors in advance to establish state equations and observation equations required in the execution process of the Kalman filtering algorithm. The state equation can be x k = Ax k-1 +w k , where x k represents the state vector at the current time, x k-1 represents the state vector at the last time, and w kA is a state transition matrix used to describe the dynamics of the system, which can be:

[0077]

[0078] The observation equation can be z k = Hx k + v k , wherein z k represents an observation vector at the current time, i.e., a measured resistance value, H is an observation matrix, which can be:

[0079]

[0080] v k is an observation noise used to represent sensor noise from electromagnetic interference (such as a strong magnetic field of an electrolytic cell) and the resistance measurement module 4, and then the corrected advanced depth and the corrected resistance value at the current time are realized by combining the Kalman filtering algorithm. The specific execution steps of the Kalman filtering algorithm are not described in detail here, and the execution steps of the existing Kalman filtering algorithm can be applied. The Kalman filtering algorithm can be a dynamic Kalman filtering algorithm. It can be understood that the above setting is beneficial to reliably suppressing electromagnetic noise and mechanical vibration interference, and the signal-to-noise ratio is improved by more than 40 dB.

[0081] In addition, the Kalman filtering algorithm can also be replaced by a wavelet transform algorithm, which is not particularly limited here and can be flexibly selected and set according to actual needs.

[0082] In some embodiments, when the interface of the current interlayer switching to be determined follows is the interface between air and electrolyte, according to the corrected resistance value and a preset interlayer switching change strategy, it is determined that the insertion end of the probe 3 has advanced to the interface of the current interlayer switching, including:

[0083] determining a second resistance change rate at the current time according to a first preset relationship; the first preset relationship is:

[0084]

[0085] wherein, represents the second resistance change rate, R k represents the corrected resistance value at the current time, R k-1 represents the corrected resistance value at the previous time, and Δt represents the time difference;

[0086] determining whether the second resistance change rate is less than a second preset threshold, the second preset threshold being set based on the resistance mutation characteristics from air to electrolyte;

[0087] If yes, it is determined that the insertion end of the probe 3 at the current time has advanced to the interface between the air and the electrolyte.

[0088] Specifically, considering that a resistance mutation occurs when the probe 3 advances from the air to the electrolyte, which is reflected in a sudden drop in resistivity (i.e., from ∞→200 μΩ·cm), the resistance change trend can be accurately identified by the first derivative, and the derivative feature at this time is that the first derivative presents a negative peak. Therefore, by comparing the size relationship between the second resistance change rate and the second preset threshold, the interface position between the air and the electrolyte can be reliably determined. In addition, when it is determined that the second resistance change rate is not less than the second preset threshold, it indicates that the probe 3 is still advancing in the air and has not reached the interface between the air and the electrolyte, and the monitoring and determination can be maintained.

[0089] In addition, the second preset threshold here can be -80 mΩ / s.

[0090] In some embodiments, when the interface of the current interlayer switching to be determined following the advancing process is the interface between the electrolyte and the aluminum liquid, according to the corrected resistance value and the preset interlayer switching change strategy, it is determined that the insertion end of the probe 3 at the current time has advanced to the interface of the current interlayer switching, including:

[0091] determining the second resistance change rate at the current time according to a first preset relationship;

[0092] determining the resistance change acceleration at the current time according to a second preset relationship, and the second preset relationship is:

[0093]

[0094] wherein, represents the resistance change acceleration, (dR / dt) k represents the second resistance change rate at the current time, (dR / dt) k-1 represents the second resistance change rate at the previous time;

[0095] determining whether the resistance change acceleration is greater than a third preset threshold, and the third preset threshold is set based on the resistance mutation characteristics from the electrolyte to the aluminum liquid;

[0096] If yes, it is determined that the insertion end of the probe 3 at the current time has advanced to the interface between the electrolyte and the aluminum liquid.

[0097] Specifically, considering that a resistance mutation occurs when the probe 3 goes from the electrolyte to the aluminum liquid, which is reflected in a second sudden drop in resistivity (i.e., from 200 μΩ·cm to 28 μΩ·cm), the mutation point (i.e., the position of the interface between the electrolyte and the aluminum liquid) can be accurately identified by the second derivative, and at this time, the derivative feature is that the second derivative presents a positive sharp peak. Therefore, by comparing the size relationship between the resistance change acceleration and the third preset threshold value, the position of the interface between the electrolyte and the aluminum liquid can be reliably determined. In addition, when it is determined that the resistance change acceleration is not greater than the third preset threshold value, it indicates that the probe 3 is still advancing in the electrolyte and has not reached the interface between the electrolyte and the aluminum liquid, and the monitoring and determination can be maintained.

[0098] In addition, the third preset threshold value herein can be 50 mΩ / s.

[0099] In some embodiments, when the interface of the current interlayer switching to be determined in the following advancing process is the interface between the aluminum liquid and the cathode, the insertion end of the probe 3 is determined to have advanced to the interface of the current interlayer switching according to the corrected resistance value and a preset interlayer switching change strategy, including:

[0100] The second resistance change rate at the current time is determined according to a first preset relationship, so as to determine the resistance change acceleration at the current time based on a second preset relationship;

[0101] It is determined whether the resistance change acceleration is less than a fourth preset threshold value, and the fourth preset threshold value is set based on the resistance mutation characteristics from the aluminum liquid to the cathode;

[0102] If yes, it is determined that the insertion end of the probe 3 has advanced to the interface between the aluminum liquid and the cathode.

[0103] Specifically, considering that a resistance mutation occurs when the probe 3 goes from the aluminum liquid to the cathode, which is reflected in a sudden rise in resistivity (i.e., from 28 μΩ·cm to >1000 μΩ·cm), the mutation point (i.e., the position of the interface between the aluminum liquid and the cathode) can still be accurately identified by the second derivative, and at this time, the derivative feature is that the second derivative presents a negative sharp peak. Therefore, by comparing the size relationship between the resistance change acceleration and the fourth preset threshold value at this time, the position of the interface between the aluminum liquid and the cathode can be reliably determined. In addition, when it is determined that the resistance change acceleration is not less than the fourth preset threshold value, it indicates that the probe 3 is still advancing in the aluminum liquid and has not reached the interface between the aluminum liquid and the cathode, and the monitoring and determination can be maintained.

[0104] In addition, the fourth preset threshold value herein can be -40 mΩ / s.

[0105] The application also provides an aluminum electrolytic cell interface position determination device, which comprises a control module 1, a driving module 2, a probe 3, and a resistance measurement module 4.

[0106] The control module 1, the driving module 2 and the probe 3 are sequentially connected, and the resistance measurement module 4 is connected with the control module 1 and the non-insertion end of the probe 3 respectively.

[0107] The control module 1 is used for executing the steps of the aluminum electrolytic cell interface position determination method.

[0108] For the aluminum electrolytic cell interface position determination device provided in the present application, please refer to the above-mentioned embodiments of the aluminum electrolytic cell interface position determination method, which will not be repeated here.

[0109] In some embodiments, the resistance measurement module 4 comprises an ohmmeter 41.

[0110] The output end of the ohmmeter 41 is connected with the control module 1, the first detection end is connected with the non-insertion end of the probe 3, and the second detection end is connected with the cathode bus of the aluminum electrolytic cell.

[0111] In the present embodiment, the resistance measurement can be reliably realized based on the principle of the ohmmeter 41, and in actual application, the ohmmeter 41 can be a high-precision industrial ohmmeter, and the resolution can be 0.1 mΩ, so as to improve the capture ability of small resistance changes.

[0112] It can be understood that the resistance measurement module 4 herein can also be set by using the four-wire Kelvin bridge method, which is not particularly limited here.

[0113] In some embodiments, the driving module 2 comprises a driving motor and a lead screw.

[0114] The control module 1, the driving motor, the lead screw and the non-insertion end of the probe 3 are sequentially connected.

[0115] Specifically, the driving motor can be a stepping motor, the control module 1 controls the stepping motor, the stepping motor drives the lead screw to further drive the probe 3 to advance into the interior of the aluminum electrolytic cell.

[0116] In addition, the driving module 2 can also integrate a rotary encoder, which can be integrated into the motor shaft of the stepping motor or integrated into the lead screw, so as to provide feedback on the actual advancing distance of the probe 3, which is beneficial to realize fine closed-loop feedback control of the advancing process of the probe 3.

[0117] It should be further pointed out that according to the above embodiments and example value settings, the interface determination error of the scheme in actual application is ≤±1.5 mm, which is smaller than the ±5 mm error in the related art, and the interface positioning precision is improved; the hardware cost is less than 20,000 yuan, which is much smaller than 100,000 yuan in the radar scheme in the related art; and the interface determination time can be ≤40 seconds, which is smaller than 3-5 minutes of the interface measurement time in the related art.

[0118] The application further provides an aluminum electrolysis cell system, comprising an aluminum electrolysis cell, and further comprising the aluminum electrolysis cell interface position determination device as described above.

[0119] For the aluminum electrolysis cell system provided in the present application, please refer to the embodiments of the aluminum electrolysis cell interface position determination method and device part, which will not be repeated here.

[0120] The various embodiments are described in the present specification in progressive order, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be mutually referred to. For the device disclosed by the embodiments, since it corresponds to the method disclosed by the embodiments, the description is relatively simple, and the relevant parts can be referred to the method part. The relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including one" does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0121] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining the interface position of an aluminum electrolytic cell, characterized in that, A control module is used in an aluminum electrolytic cell interface position determination device. The device further includes a drive module, a probe, and a resistance measurement module. The control module, drive module, and probe are connected sequentially. The resistance measurement module is connected to the non-insertion ends of both the control module and the probe. The aluminum electrolytic cell interface position determination method includes: The drive module controls the insertion end of the probe to move into the interior of the aluminum electrolysis cell from a preset starting position. During the process, the resistance value measured by the resistance measurement module at the current moment is obtained; Based on the current depth of advance and the measured resistance value, a preset filtering algorithm is used to determine the corrected depth of advance and the corrected resistance value at the current moment. Based on the corrected resistance value and the preset interlayer switching change strategy, determine whether the insertion end of the probe has advanced to the interface of the current interlayer switching at the current moment; If so, determine the depth of the correction as the target interface position corresponding to the current interlayer switching, until the target interface position is determined during different interlayer switching within the aluminum electrolysis cell following the advancement process.

2. The method for determining the interface position of an aluminum electrolytic cell as described in claim 1, characterized in that, The drive module controls the insertion end of the probe to advance into the aluminum electrolysis cell from a preset starting position, including: The drive module controls the insertion end of the probe to start from a preset starting position and advance into the interior of the aluminum electrolysis cell at a first preset speed. After determining the corrected depth of advance and the corrected resistance value at the current moment based on the current advance depth and the measured resistance value, and using a preset filtering algorithm, the method further includes: The first resistance change rate is determined based on the corrected resistance value at the current moment, the corrected resistance value at the previous moment, and the change in position. Determine whether the rate of change of the first resistance is greater than a first preset threshold. If so, the drive module controls the insertion end of the probe to advance into the aluminum electrolysis cell at a second preset speed, where the second preset speed is less than the first preset speed.

3. The method for determining the interface position of an aluminum electrolytic cell as described in claim 1, characterized in that, Based on the current depth of advance and the measured resistance value, a preset filtering algorithm is used to determine the corrected depth of advance and the corrected resistance value at the current moment, including: Based on the measured resistance value and depth of advance at the current moment, the corrected resistance value and corrected depth of advance at the previous moment, the corrected depth of advance and the corrected resistance value at the current moment are determined using the Kalman filter algorithm.

4. The method for determining the interface position of an aluminum electrolytic cell as described in any one of claims 1 to 3, characterized in that, When the interface to be determined during the current interlayer switching process is the interface between air and electrolyte, based on the corrected resistance value and the preset interlayer switching change strategy, it is determined that the insertion end of the probe has advanced to the interface of the current interlayer switching, including: The second resistance change rate at the current moment is determined according to the first preset relationship; the first preset relationship is: in, R represents the rate of change of the second resistance. k R represents the corrected resistance value at the current moment. k-1 This represents the correction resistor value at the previous moment, and Δt represents the time difference. Determine whether the second resistance change rate is less than a second preset threshold, the second preset threshold being set based on the resistance change characteristics from the air to the electrolyte; If so, it is determined that the insertion end of the probe has been advanced to the interface between the air and the electrolyte at the current moment.

5. The method for determining the interface position of an aluminum electrolytic cell as described in claim 4, characterized in that, When the interface to be determined during the current interlayer switching process is the interface between the electrolyte and the molten aluminum, based on the corrected resistance value and the preset interlayer switching change strategy, it is determined that the insertion end of the probe has advanced to the interface of the current interlayer switching, including: The second resistance change rate at the current moment is determined according to the first preset relationship; The acceleration of the resistance change at the current moment is determined according to the second preset relationship, which is: in, The acceleration due to the change in resistance is expressed as (dR / dt). k The second resistance change rate at the current moment is expressed as (dR / dt). k-1 This represents the rate of change of the second resistance at the previous moment; Determine whether the acceleration of the resistance change is greater than a third preset threshold, the third preset threshold being set based on the characteristics of the sudden change in resistance from the electrolyte to the molten aluminum; If so, it is determined that the insertion end of the probe has been advanced to the interface between the electrolyte and the molten aluminum at the current moment.

6. The method for determining the interface position of an aluminum electrolytic cell as described in claim 5, characterized in that, When the interface to be determined during the current interlayer switching process is the interface between the molten aluminum and the cathode, based on the corrected resistance value and the preset interlayer switching change strategy, it is determined that the insertion end of the probe has advanced to the interface of the current interlayer switching, including: The second resistance change rate at the current moment is determined according to the first preset relationship, so as to determine the resistance change acceleration at the current moment based on the second preset relationship; Determine whether the acceleration of the resistance change is less than a fourth preset threshold, which is set based on the characteristics of the sudden change in resistance from the molten aluminum to the cathode; If so, it is determined that the insertion end of the probe has been advanced to the interface between the molten aluminum and the cathode at the current moment.

7. A device for determining the interface position of an aluminum electrolytic cell, characterized in that, Includes a control module, a drive module, probes, and a resistance measurement module; The control module, the drive module, and the probe are connected in sequence, and the resistance measurement module is connected to the control module and the non-insertion end of the probe, respectively. The control module is used to perform the steps of the aluminum electrolytic cell interface position determination method as described in any one of claims 1 to 6.

8. The aluminum electrolytic cell interface position determination device as described in claim 7, characterized in that, The resistance measurement module includes an ohmmeter; The output terminal of the ohmmeter is connected to the control module, the first detection terminal is connected to the non-insertion terminal of the probe, and the second detection terminal is connected to the cathode bus of the aluminum electrolysis cell.

9. The aluminum electrolytic cell interface position determination device as described in claim 7, characterized in that, The drive module includes a drive motor and a lead screw; The control module, the drive motor, the lead screw, and the non-insertion end of the probe are connected in sequence.

10. An aluminum electrolysis cell system, characterized in that, It includes an aluminum electrolytic cell, and also includes the aluminum electrolytic cell interface position determination device as described in any one of claims 7 to 9.

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