A control system and method for energy balance of an aluminum and aluminum-based alloy electrolytic cell

Abstract

The present application relates to a kind of aluminium and aluminium-based alloy electrolytic cell energy balance control system and method, the control system includes sensor acquisition unit, control unit, ethernet and host computer distributed control system, sensor acquisition unit includes current acquisition sensor, tank voltage acquisition sensor and temperature acquisition sensor, the data input to control unit after sensor acquisition unit collection, by ethernet transmission to host computer distributed cluster system, after inference calculation is carried out to the data received by host computer distributed control system, energy balance control logic is obtained, and energy balance control logic is transmitted to control unit by ethernet again, so that control unit controls the voltage of electrolytic cell according to energy balance control logic.The control system can effectively solve the problem that electrolytic cell cannot control electrolytic cell energy balance due to inaccurate and untimely temperature measurement.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum and aluminum-based alloy electrolytic cells, and relates to a control system and method for energy balance of an aluminum and aluminum-based alloy electrolytic cell. BACKGROUND

[0002] The control of energy balance of an aluminum and aluminum-based alloy electrolytic cell is the key to the stable operation and flexible production technology of the electrolytic cell. At present, the industry has determined a control strategy based on the furnace and the core of the superheat. A regular furnace and appropriate superheat can improve the stability and current efficiency of the electrolytic cell.

[0003] However, due to the strong corrosiveness of high-temperature electrolyte, there is currently no probe that can detect the electrolyte temperature for a long time online. The cell temperature can only be measured by a handheld thermocouple at regular intervals every day, and the degree of crust at the aluminum outlet is used to judge the size of the superheat. The change trend of the cell temperature and the superheat obtained through the above method is used to judge the energy change trend of the electrolytic cell and make targeted adjustments to ensure the energy balance of the electrolytic cell. The above method for energy balance has hysteresis, one-sidedness and subjectivity, and cannot accurately reflect the energy balance change of the electrolytic cell in a timely manner. At the same time, the judgment and adjustment are made by engineers, which requires high requirements for engineers and has system risks.

[0004] At the same time, the current online judgment of the energy balance of the electrolytic cell is basically implemented around the fire eye. For example, patent CN107248157A proposes to convert the fire eye image into a digital image, construct an image matrix, extract the temperature, area and texture features of the fire eye, and realize the automatic fire observation function. Patent CN107204004A proposes to use the method of video dynamic feature extraction to realize the feature judgment of the fire eye. Patent CN111996556A proposes to measure the temperature around the fire eye to judge the superheat of the electrolytic cell. However, the method of judging the change of the superheat based on the fire eye is affected by the test environment and the electrolytic operation, and it is difficult to guarantee the result of judging the superheat from the fire eye due to the high requirements of the shooting system and the temperature measurement system.

[0005] In view of the above technical defects of the prior art, there is an urgent need to develop a new control system and method for the energy balance of an aluminum and aluminum-based alloy electrolytic cell. SUMMARY

[0006] To solve the problems in the prior art, the application provides a control system and method for the energy balance of an aluminum and aluminum-based alloy electrolytic cell, which can solve the problem that the electrolytic cell cannot control the energy balance due to inaccurate and untimely temperature measurement.

[0007] To achieve the above purpose, the application provides the following technical solutions:

[0008] A kind of aluminium and aluminium base alloy electrolytic cell energy balance control system, it includes sensor acquisition unit, control unit, ethernet and host computer distributed control system, it is characterized in that, the sensor acquisition unit, control unit, ethernet and host computer distributed cluster system are sequentially connected, the sensor acquisition unit includes current acquisition sensor, tank voltage acquisition sensor and temperature acquisition sensor, the current acquisition sensor is used to collect the current data of electrolytic cell, the tank voltage acquisition sensor is used to collect the voltage data of electrolytic cell, the temperature acquisition sensor is used to collect the temperature data of electrolytic cell, the data of sensor acquisition unit is input to the control unit, and then it is transmitted to the host computer distributed cluster system by the ethernet, after the inference calculation of the data received by the host computer distributed control system, the energy balance control logic is obtained, and then the energy balance control logic is fed back to the control unit by the ethernet, so that the control unit controls the voltage of electrolytic cell according to the energy balance control logic fed back, and the energy balance control logic is as shown in Figure 5 Wherein, a is the allowed thickest crust thickness, b is the allowed thinnest crust thickness, k1, k2, f1, f2, g are all system adjustment constants, all less than zero, q is heat flux density, is the change value in judging time T, is the change rate of q in T, is the voltage adjustment decision made.

[0009] Preferably, the electrolytic cell is divided into 8 characteristic zones, and the 8 characteristic zones are divided into 2 types, namely, end characteristic zones and middle characteristic zones, wherein the end characteristic zones are characteristic zone I and characteristic zone VIII located at both ends of the electrolytic cell, and the middle characteristic zones are characteristic zones II-VII located between the two ends of the electrolytic cell, and the temperature acquisition sensor in each end characteristic zone is located at the position of the first steel bar in the end characteristic zone, and the temperature acquisition sensor in each middle characteristic zone is located at the position of the middle steel bar in the middle characteristic zone.

[0010] Preferably, the temperature acquisition sensor in each end characteristic zone and the temperature acquisition sensor in each middle characteristic zone include a plurality of isotherm pre-embedded temperature probes and a plurality of tank shell temperature probes.

[0011] Preferably, the host computer distributed control system calculates the heat flux density of the side and bottom regions of the electrolytic cell using the measured temperatures of the plurality of isotherm pre-embedded temperature probes and the plurality of tank shell temperature probes and the thermal conductivity of the lining material of the electrolytic cell, and calculates the average heat flux density based on the heat flux density of the side and bottom regions.

[0012] Preferably, the host computer distributed control system calculates the crust thickness by using the average heat flux, the thermal resistance of the lining material of the electrolytic cell, the thermal resistance of the artificial leg and the thermal conductivity of the cell side.

[0013] Preferably, the host computer distributed control system infers the cold and hot trend of the electrolytic cell according to the average heat flux and the crust thickness, and modulates the voltage based on the cold and hot trend of the electrolytic cell to obtain the energy balance control logic.

[0014] In addition, the present application also provides a control method for energy balance of an aluminum and aluminum alloy electrolytic cell, characterized in that it is performed by using the above-mentioned control system for energy balance of an aluminum and aluminum alloy electrolytic cell, and comprises the following steps:

[0015] 1) collecting the current data, temperature data and voltage data of the electrolytic cell by the sensor acquisition unit and inputting the collected data into the control unit;

[0016] 2) transmitting the data to the host computer distributed cluster system by the control unit through the Ethernet;

[0017] 3) obtaining the energy balance control logic after the host computer distributed control system performs inference calculation on the received data;

[0018] 4) transmitting the energy balance control logic to the control unit by the host computer distributed control system through the Ethernet, so that the control unit controls the electrolytic cell according to the energy balance control logic.

[0019] Preferably, the step 3) is specifically:

[0020] 3.1) calculating the heat flux density of the side and bottom areas of the electrolytic cell by the host computer distributed control system using the measured temperature and the thermal conductivity of the lining material of the electrolytic cell, and calculating the average heat flux density based on the heat flux density of the side and bottom areas;

[0021] 3.2) calculating the crust thickness by the host computer distributed control system using the average heat flux, the thermal resistance of the lining material of the electrolytic cell, the thermal resistance of the artificial leg and the thermal conductivity of the cell side;

[0022] 3.3) inferring the cold and hot trend of the electrolytic cell according to the average heat flux and the crust thickness by the host computer distributed control system, and modulating the voltage based on the cold and hot trend of the electrolytic cell to obtain the energy balance control logic.

[0023] Preferably, the crust thickness includes the corresponding crust thickness of the anode lower surface, and the average value is marked as The average value of the thickness of the crust corresponding to the upper surface of the cathode is marked as The average value of the thickness of the crust corresponding to the upper surface of the electrolyte is marked as The average thickness of the crust on the side is wherein is a weight coefficient, and the sum of the values is 1.

[0024] Preferably, the energy balance control logic is as shown in Figure 5 wherein a is the maximum allowed thickness of the crust, b is the minimum allowed thickness of the crust, k1, k2, f1, f2, g are system adjustment constants, all less than zero, q is the heat flux density, is the change value in the judgment time T, is the change rate of q in T, is the voltage adjustment decision made.

[0025] Compared with the prior art, the energy balance control system and method for the aluminum and aluminum-based alloy electrolytic cell of the present application has one or more of the following beneficial technical effects:

[0026] 1. The present application uses the sidewall temperature and the embedded thermocouple temperature to calculate the sidewall heat dissipation and the cold and hot trend of the electrolytic cell, and adjusts the voltage to control the energy balance of the electrolytic cell, thereby solving the problem that the electrolytic cell cannot control the energy balance due to inaccurate and untimely temperature measurement.

[0027] 2. The present application can control the furnace wall to be 8-12 cm, control the electrolysis temperature to be 950℃, make the whole furnace shape regular, increase the service life of the electrolytic cell by 1.5 years, and increase the current efficiency from 92% to 94%. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a schematic view of the side of the electrolytic cell.

[0029] Figure 2 is an enlarged view of part A in Figure 1

[0030] Figure 3 is an enlarged view of part B in Figure 1

[0031] Figure 4 is a cross-sectional view of the electrolytic cell.

[0032] Figure 5 is an energy balance control logic diagram.

[0033] ​​In the figure, A-characteristic area I, B-characteristic area II, C-characteristic area III, D-characteristic area IV, E-characteristic area V, F-characteristic area VI, G-characteristic area VII, H-characteristic area VIII, a-steel rod, b-temperature acquisition sensor, 1-side insulation material, 2-artificial extension leg, 3-anode, 4-side electrolyte crust, 5-electrolyte liquid, 6-aluminum liquid, 7 and 8-cathode carbon block, 9-cathode steel rod, 10-dry anti-seepage material. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments. The content of the embodiments is not intended to limit the scope of protection of the present invention.

[0035] This invention relates to a control system and method for energy balance in aluminum and aluminum-based alloy electrolytic cells. It uses the sidewall temperature and the temperature of the pre-embedded thermocouple to calculate the heat dissipation of the sidewall and the heating and cooling trend of the electrolytic cell, and adjusts the energy balance of the electrolytic cell by setting the voltage. This solves the problem that the energy balance of the electrolytic cell cannot be controlled due to inaccurate or untimely temperature measurement.

[0036] The energy balance control system for aluminum and aluminum-based alloy electrolytic cells of the present invention includes a sensor acquisition unit, a control unit, an Ethernet network, and a host computer distributed control system. The sensor acquisition unit, control unit, Ethernet network, and host computer distributed cluster system are connected sequentially.

[0037] The sensor acquisition unit includes a current acquisition sensor, a cell voltage acquisition sensor, and a temperature acquisition sensor. The current acquisition sensor is used to acquire the current data of the electrolytic cell. The cell voltage acquisition sensor is used to acquire the voltage data of the electrolytic cell. The temperature acquisition sensor is used to acquire the temperature data of the electrolytic cell.

[0038] In this invention, the installation positions and functions of the current acquisition sensor and the cell voltage acquisition sensor are the same as those of the current acquisition sensor and the cell voltage acquisition sensor in the prior art electrolytic cell energy balance system. Therefore, for simplicity, they will not be described in detail here. The focus of this invention is on acquiring temperature data of the electrolytic cell through the temperature acquisition sensor; therefore, the installation position and function of the temperature acquisition sensor will be described in detail below.

[0039] like Figure 1 As shown, in this invention, the electrolytic cell is divided into eight characteristic zones, namely, A-characteristic zone I, B-characteristic zone II, C-characteristic zone III, D-characteristic zone IV, E-characteristic zone V, F-characteristic zone VI, G-characteristic zone VII, and H-characteristic zone VIII. The lengths of each characteristic zone are similar or equal; for example, each characteristic zone has six steel rods a.

[0040] The eight feature areas are divided into two types: end feature areas and middle feature areas. The end feature areas are A-feature area I and H-feature area VIII, located at both ends of the electrolytic cell. The middle feature areas are feature areas II-VII, located between the two ends of the electrolytic cell.

[0041] like Figure 2 As shown, in this invention, the temperature acquisition sensor b in each of the end feature areas is located at the position of the first steel rod a in the end feature area, that is, at the position of the steel rod closest to the end.

[0042] At the same time, such as Figure 3 As shown, the temperature acquisition sensor b in each of the central feature areas is located at the position of the middle steel rod a in the central feature area, that is, on one of the two middle steel rods a in the central feature area.

[0043] By arranging the temperature acquisition sensor b in the above manner, it can be ensured that the temperature data acquired by the temperature acquisition sensor b can better reflect the actual temperature of the electrolytic cell.

[0044] In this invention, the temperature acquisition sensor in each of the end feature areas and the temperature acquisition sensor in each of the middle feature areas includes multiple isotherm-embedded temperature probes and multiple tank shell temperature probes. This ensures that the acquired temperature data more accurately reflects the actual temperature across the entire cross-section of the electrolytic cell.

[0045] like Figure 4 As shown, for the end feature area, two isothermal pre-embedded temperature probes are installed on its side, and one isothermal pre-embedded temperature probe is installed on the center line of the electrolytic cell. The power input terminals of the two isothermal pre-embedded temperature probes installed on the side are labeled Ai1 and Ai3, respectively, and the power output terminals are labeled Bi1 and Bi3, respectively. The isothermal pre-embedded temperature probe installed on the center line of the electrolytic cell is labeled Di, and it is used to collect temperature data between the cathode steel rod 9 and the dry anti-seepage material 10 of the electrolytic cell.

[0046] Furthermore, for the end feature area, four tank shell temperature probes are installed on its sides, and one tank shell temperature probe is installed at the center line of the tank bottom. The power input terminals of the four side-mounted tank shell temperature probes are marked AWi0, AWi1, AWi2, and AWi3, respectively, and the power output terminals are marked Bwi0, BWi1, BWi2, and BWi3, respectively. They are used to collect the surface temperature of the tank shell on the sides. The tank shell temperature probe installed at the center line of the tank bottom is marked Dwi, and it is used to collect the surface temperature of the tank shell at the center line of the tank bottom.

[0047] For the middle characteristic zone, the number and installation position of the isotherm pre-embedded temperature probes and the tank shell temperature probes are the same as those of the end characteristic zone, and therefore, for the sake of simplicity, they will not be described in detail herein.

[0048] The data collected by the sensor collection unit is input to the control unit. The control unit can analyze and preprocess the collected data. The analysis and preprocessing are conventional techniques for processing collected data of sensors in the prior art, and are not the focus of the present application, and therefore will not be described in detail.

[0049] After the control unit analyzes and preprocesses the collected data, the Ethernet is used to feed back the upper computer distributed cluster system.

[0050] The upper computer distributed control system obtains energy balance control logic after reasoning calculation on the received data. Specifically,

[0051] Firstly, the upper computer distributed control system can calculate the heat flux density of the side and bottom regions of the electrolytic tank by using the measured temperature of the plurality of isotherm pre-embedded temperature probes and the plurality of tank shell temperature probes and the thermal conductivity of the lining material of the electrolytic tank, and calculate the average heat flux density based on the heat flux density of the side and bottom regions.

[0052] The heat flux density of the side and bottom regions is calculated by using the measured temperature and the thermal conductivity of the lining material, and the formula is as follows: In the formula, q is the heat flux density, Tij is the isotherm temperature, TTij is the tank shell temperature, λ is the thermal conductivity of the lining material at the two temperature measuring points TTij and Tij, and Δx is the distance between the two temperature measuring points TTij and Tij.

[0053] Average heat flux density In the formula, qij is the heat flux density of a single test unit, Aij is the area of a single mapping unit, and Aall is the total area of the test units.

[0054] Secondly, the upper computer distributed control system calculates the crust thickness by using the average heat flux density, the thermal resistance of the lining material of the electrolytic tank, the thermal resistance of the artificial leg, and the thermal conductivity of the furnace wall.

[0055] In the formula, the heat flux density, the thermal resistance of the lining material, the thermal resistance of the artificial leg, and the thermal conductivity of the furnace wall are used to calculate the crust thickness.

[0056]

[0057] In the formula,

[0058] L: Crust thickness

[0059] λ: furnace side heat transfer coefficient

[0060] t: liquidus temperature

[0061] t0: sidewall temperature

[0062] c: lining material thermal resistance

[0063] lleg / λleg: leg thermal resistance.

[0064] Anode lower surface corresponding crust thickness is noted , its minimum value is noted , its maximum value is noted , its average value is , with being the lateral test cell area, being the lateral test cell anode lower surface corresponding crust thickness, being the lateral area sum.

[0065] Cathode upper surface corresponding crust thickness is noted , its minimum value is noted , its maximum value is noted , its average value is , with being the lateral test cell area, being the lateral test cell cathode upper surface corresponding crust thickness, being the lateral area sum.

[0066] Electrolyte upper surface corresponding crust thickness is noted , its minimum value is noted , its maximum value is noted , its average value is , with being the lateral test cell area, being the lateral test cell electrolyte upper surface corresponding crust thickness, being the lateral area sum.

[0067] Bottom corresponding precipitate or crust thickness is noted , its minimum value is noted , its maximum value is noted , its average value is , with being the bottom test cell area, being the bottom test cell corresponding crust thickness, being the bottom area sum.

[0068] Lateral average crust thickness , with being weighting coefficients, the sum of which is 1.

[0069] After the crust thickness is obtained, the furnace inner profile of the whole electrolytic cell can be simulated, and the cold and hot trend of the electrolytic cell and the electrolytic process adjustment direction are determined according to the furnace inner profile change trend.

[0070] Finally, the host computer distributed control system infers the cold and hot trend of the electrolytic cell according to the average heat flux density and the crust thickness, and performs voltage modulation based on the cold and hot trend of the electrolytic cell to obtain the energy balance control logic.

[0071] Specifically, the energy balance control logic is as shown in the following formula: Figure 5 Wherein, a is the allowed thickest crust thickness, b is the allowed thinnest crust thickness, k1, k2, f1, f2, g are all system adjustment constants, and are all less than zero, q is the average heat flux density, is the change value in the judgment time T, is the change rate of q in T, is the voltage adjustment decision made.

[0072] The energy balance control logic of the present application can also be used in flexible electrolytic production technology, but due to the process limitation on the pole distance, the adjustment defined in the present application is limited in the range of 3-8 cm pole distance.

[0073] For the judgment of the furnace bottom crust and precipitation, if the weighted average value is greater than 1 cm, the aluminum level should be appropriately reduced, the furnace bottom temperature and the aluminum liquid flow speed should be increased, and the precipitation resolution capacity should be improved according to the comprehensive situation of the electrolytic process.

[0074] In the present application, after the energy balance control logic is obtained, the host computer distributed control system transmits the energy balance control logic to the control unit through the Ethernet, so that the control unit controls the voltage of the electrolytic cell according to the energy balance control logic. Through the control of the voltage, the control of the energy balance can be realized.

[0075] The above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the implementation modes of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the implementation modes cannot be exhausted. Any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A control system for energy balance in an aluminum and aluminum-based alloy electrolytic cell, comprising a sensor acquisition unit, a control unit, an Ethernet network, and a host computer distributed control system, characterized in that, The sensor acquisition unit, control unit, Ethernet, and host computer distributed cluster system are connected in sequence. The sensor acquisition unit includes a current acquisition sensor, a cell voltage acquisition sensor, and a temperature acquisition sensor. The current acquisition sensor is used to acquire the current data of the electrolytic cell, the cell voltage acquisition sensor is used to acquire the voltage data of the electrolytic cell, and the temperature acquisition sensor is used to acquire the temperature data of the electrolytic cell. After the data acquired by the sensor acquisition unit is input to the control unit, it is transmitted to the host computer distributed cluster system through the Ethernet. The host computer distributed control system performs inference calculations on the received data to obtain energy balance control logic, and then feeds the energy balance control logic back to the control unit through the Ethernet, so that the control unit controls the voltage of the electrolytic cell according to the feedback energy balance control logic. The upper-level distributed control system performs inference calculations on the received data to obtain the energy balance control logic, which includes: The host computer distributed control system calculates the heat flux density of the side and bottom regions of the electrolytic cell by measuring the temperature and the thermal conductivity of the lining material of the electrolytic cell, and calculates the average heat flux density based on the heat flux density of the side and bottom regions. The host computer distributed control system calculates the crust thickness using the average heat flux density, the thermal resistance of the lining material of the electrolytic cell, the thermal resistance of the artificial extension leg, and the thermal conductivity of the furnace side. The host computer distributed control system infers the heating and cooling trend of the electrolytic cell based on the average heat flux density and the shell thickness, and modulates the voltage based on the heating and cooling trend of the electrolytic cell to obtain the energy balance control logic.

2. The energy balance control system for aluminum and aluminum-based alloy electrolytic cells according to claim 1, characterized in that, The electrolytic cell is divided into 8 feature zones, which are further divided into two types: end feature zones and middle feature zones. The end feature zones are feature zones I and VIII located at both ends of the electrolytic cell, and the middle feature zones are feature zones II-VII located between the two ends of the electrolytic cell. In addition, the temperature acquisition sensor in each end feature zone is located at the position of the first steel bar in the end feature zone, and the temperature acquisition sensor in each middle feature zone is located at the position of the middle steel bar in the middle feature zone.

3. The energy balance control system for aluminum and aluminum-based alloy electrolytic cells according to claim 2, characterized in that, The temperature acquisition sensor in each of the end feature areas and the temperature acquisition sensor in each of the middle feature areas includes multiple isotherm embedded temperature probes and multiple slot shell temperature probes.

4. The energy balance control system for aluminum and aluminum-based alloy electrolytic cells according to claim 3, characterized in that, The host computer distributed control system uses the measured temperatures of the multiple isotherm embedded temperature probes and multiple tank shell temperature probes, as well as the thermal conductivity of the lining material of the electrolytic cell, to calculate the heat flux density of the side and bottom regions of the electrolytic cell, and calculates the average heat flux density based on the heat flux density of the side and bottom regions.

5. The energy balance control system for aluminum and aluminum-based alloy electrolytic cells according to claim 4, characterized in that, The host computer distributed control system calculates the crust thickness using the average heat flux density, the thermal resistance of the lining material of the electrolytic cell, the thermal resistance of the artificial extension legs, and the thermal conductivity of the furnace side.

6. The energy balance control system for aluminum and aluminum-based alloy electrolytic cells according to claim 5, characterized in that, The host computer distributed control system infers the heating and cooling trend of the electrolytic cell based on the average heat flux density and the shell thickness, and modulates the voltage based on the heating and cooling trend of the electrolytic cell to obtain the energy balance control logic.

7. A method for controlling the energy balance of an aluminum and aluminum-based alloy electrolytic cell, characterized in that, It employs the energy balance control system for aluminum and aluminum-based alloy electrolytic cells as described in any one of claims 1-6, and includes the following steps: 1) The sensor acquisition unit collects the current, temperature, and voltage data of the electrolytic cell and inputs the collected data to the control unit; 2) The control unit transmits data to the host computer distributed cluster system via the Ethernet; 3) The host computer distributed control system performs inference calculations on the received data to obtain the energy balance control logic; 4) The host computer distributed control system transmits the energy balance control logic to the control unit via the Ethernet, so that the control unit controls the electrolytic cell according to the energy balance control logic.

8. The method for controlling the energy balance of an aluminum and aluminum-based alloy electrolytic cell according to claim 7, characterized in that, The crust thickness includes the crust thickness corresponding to the lower surface of the anode, and its average value is marked as follows: ; The average value of the junction thickness corresponding to the upper surface of the cathode is marked as follows. The average value of the crust thickness corresponding to the upper surface of the electrolyte solution is marked as follows: Therefore, the average thickness of the lateral crust is ,in These are the weighting coefficients, and their sum is 1.

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