Two-level and cathode voltage drop calculation method for aluminum electrolysis cell

Abstract

The present invention relates to the technical field of aluminum electrolysis parameter measurement. Disclosed is a two-level and cathode voltage drop calculation method for an aluminum electrolysis cell. Voltage signal data and displacement signal data are collected and stored in arrays; the data is preprocessed; a trigger condition for an air and electrolyte interface and a trigger condition for an electrolyte and aluminum liquid interface are set; for each group of data in the arrays, an electrolyte level and an aluminum level are calculated and rationality determination is performed; and average values are taken as final values. The present invention achieves unmanned measurement of process parameters such as aluminum electrolysis cell electrolyte and aluminum liquid heights and cathode voltage drop, thereby improving the automation and intelligence level of the electrolysis process, reducing the risks and costs of manual measurement, and improving testing efficiency and accuracy.

Description

A method for calculating the voltage drop at both the horizontal and cathode levels of an aluminum electrolytic cell. Technical Field This invention relates to the field of aluminum electrolysis parameter measurement technology, specifically a method for calculating the voltage drop across two levels and the cathode in an aluminum electrolysis cell. Background Technology Aluminum electrolysis is a typical labor-intensive industry, requiring repetitive manual measurement of many process operating parameters. Typical parameters include two levels (aluminum level H_AL and electrolyte level H_BA) and cathode voltage drop (CVD). Aluminum level refers to the height of the molten aluminum in the electrolytic cell, serving as the primary standard for electrolysis managers to determine the aluminum output. Electrolytic level refers to the height of the electrolyte melt in the electrolytic cell, providing a direct indication of the cell's thermal balance. Cathode voltage drop directly reflects the operating status of the cathode and the deposition on its surface. When the iron content in the molten aluminum surges, it is necessary to measure all cathode voltage drops and steel bar temperatures to pinpoint the cathode failure point. Patent ZL201710255062.0 discloses a device for measuring the two horizontal and cathode voltage drops by setting up a device on the upper structure of the electrolytic cell. Subsequently, a temperature measuring device was added in the patent application number 202011403535.5. Patent ZL201910531861.5 discloses a device for accurately measuring the electrolyte temperature, electrolyte primary crystal temperature, electrolyte equidistant voltage drop, electrolyte height, aluminum molten height, and electrolytic cell cathode voltage drop through online measurement. It is evident that replacing traditional manual measurement with automatic measurement has become a trend. As my country's aluminum electrolysis industry has increasingly demanded intelligent and digital upgrades in recent years, this issue has become more prominent. Summary of the Invention This invention provides a method for calculating the two levels and cathode voltage drop of an aluminum electrolytic cell, enabling automatic measurement of aluminum level, quality level, and cathode voltage drop, thereby improving the intelligence and digitalization level of electrolytic production management. Specifically, it includes: S1. Based on the electrolyte temperature of the aluminum electrolysis cell, the two levels and the pressure drop at the bottom of the furnace, use an online measurement system to collect voltage signal data and store it in array D[M][N], and collect displacement signal data and store it in array S[M]. S2. Extract the first column of array D[M][N], array D[M][0]. Perform data preprocessing on array D[M][0] and array S[M] to obtain array D1[M][0] and array S1[M]. Then, use a filtering algorithm to filter array D1[M][0] to obtain the filtered array D2[M][0]. S3. Set the trigger condition TRG1 for the air and electrolyte interface and the trigger condition TRG2 for the electrolyte and aluminum liquid interface. Perform sequential inspection on array D2[M][0]. When TRG1 is triggered, record the row number B of the array. When TRG2 is triggered, record the row number L of the array. S4. Calculate the quality level and aluminum level using array S1[M], where the quality level height H_BA[0] = S1[L] - S1[B], the aluminum level height H_AL[0] = DSP - S1[L], DSP is the distance from the probe to the bottom of the electrolytic cell, and the cathode voltage drop CVD[0] = AVE(D2[L][0]: D2[L+C][0]), where the value of C is the set value; S5. Determine the rationality of the data of the quality level height H_BA[0], aluminum level height H_AL[0] and cathode voltage drop CVD[0]. If the data is reasonable, output normally; if the data is unreasonable, output H_BA[0] = 1111, H_AL[0] = 1111, CVD[0] = 1111. S6. Extract the remaining columns from array D[M][N], repeat steps S2-S4, and output the quality level array H_BA[N], aluminum level array H_AL[N], and cathode voltage drop array CVD[N]. The quality level is the average of the reasonable data in array H_BA[N], the aluminum level is the average of the reasonable data in array H_AL[N], and the cathode voltage drop is the average of the reasonable data in array CVD[N]. In step S1, M is the number of rows of data collected, and N is a natural number greater than 0 and less than the number of cathode steel rods. In step S2, the preprocessing methods include replacing abnormal data, bridging breakpoints in theoretical data, and using constants to fill in the tail of the array; the filtering methods include amplitude limiting filtering, moving average filtering, median filtering, and weighted average filtering. Step S3 includes the following steps: S301. Calculate the small slope of the data in array D2[M][0] to obtain the small slope SP1[i] = D2[i][0] - D2[ik][0], and store it in array SP1[M], where k is a natural number from 2 to 30; S302. Perform a large slope calculation on the data in array D2[M][0] to obtain the large slope SP2[i] = D2[i][0] - D2[iK][0], and store it in array SP2[M], where K is a natural number from 30 to 200; S303. Set the trigger condition TRG1 for the air and electrolyte interface, and perform sequential inspection of array D2[M][0]. When TRG1 is triggered, record the row number B of the array, where TRG1 is the result of logical operation including small slope, large slope, array value and time. S304. Determine the trigger condition TRG2 for the interface between the electrolyte and the aluminum liquid. Continue to inspect the array D2[M][0]. When TRG2 is triggered, record the row number L of the array. TRG2 is the result of a logical operation including small slope, large slope, array value and time. In step S4, the value of C is a set natural number between 1 and 300. In step S5, for cases where the data outputs are unreasonable, such as H_BA[0] = 1111, H_AL[0] = 1111, and CVD[0] = 1111, manual inspection of the cathode condition of the electrolytic cell is introduced to check whether it is normal. The present invention has the following beneficial effects and advantages: The invention provides a method for calculating the two levels and cathode voltage drop of an aluminum electrolytic cell, which enables unmanned measurement of process parameters such as electrolyte, aluminum liquid height, and cathode voltage drop in the aluminum electrolytic cell. This improves the automation and intelligence level of the electrolysis process, reduces the risks and costs of manual measurement, and enhances testing efficiency and accuracy. Attached Figure Description Figure 1 is a flowchart of a method for calculating the voltage drop of two levels and the cathode in an aluminum electrolytic cell according to the present invention. Detailed Implementation The invention will be further described below with reference to the accompanying drawings. As shown in Figure 1, the present invention provides a method for calculating the voltage drop across the two levels and the cathode of an aluminum electrolytic cell. Example 1: Measurements of the two-level and cathode voltage drop were performed on a 350kA electrolytic cell with 48 cathode steel rods. Specifically, the following steps are included: S1. Based on the electrolyte temperature, two levels, and furnace bottom pressure drop of the aluminum electrolysis cell, voltage signal data is collected using an online measurement system and stored in array D[M][N]. Displacement signal data is collected and stored in array S[M]. M is the number of rows of collected data, and N is a natural number greater than 0 and less than the number of cathode steel bars. In this embodiment, M is the number of rows of collected data (1000), and N is the number of cathode steel bars (48). The voltage signal array is D[M][N].

[1000]

[0048] , the displacement data array is S

[1000] . S2, Extract array D The first column array D in

[1000]

[0048]

[1000] [0], and for array D

[1000] [0] and array S

[1000] Preprocessing steps such as replacing abnormal data, bridging breakpoints with theoretical data, and padding the array tail with constants are performed to obtain arrays D1[M][0] and S1[M]. In this embodiment, array D... The preliminary processing method for

[1000] [0] is as follows: If array D If a data D[i][0] in

[1000] [0] is greater than 1.5 times both the preceding and following data, then the data D[i][0] is the average of the preceding data D[i-1][0] and the following data D[i+1][0], i.e., D1[i][0] = (D[i-1][0] + D[i+1][0]) / 2. Otherwise, the data is not processed, i.e., D1[i][0] = D[i][0]. For array S The preliminary processing of

[1000] is the same as described above. Filtering algorithms such as amplitude limiting filter, moving average filter, median filter, and weighted average filter are used to filter array D1.

[1000] [0] are filtered. In this embodiment, a moving average filter is used to filter array D1.

[1000] [0] is filtered, and its calculation method is the average of the first 5 data points and the last 5 data points of the data D1[i][0], that is: D2[i][0]=(D1[i-5][0]+D1[i-4][0]+D1[i-3][0]+D1[i-2][0]+D1[i-1][0]+D 1[i][0]+D1[i+1][0]+D1[i+2][0]+D1[i+3][0]+D1[i+4][0]+D1[i+5][0]) / 11. Get the filtered array D2

[1000] [0]. S3. Set the trigger condition TRG1 for the air and electrolyte interface and the trigger condition TRG2 for the electrolyte and aluminum liquid interface. Perform sequential inspection of array D2[M][0] from front to back. When TRG1 is triggered, record the row number B of the array. When TRG2 is triggered, record the row number L of the array. Specifically, it includes the following steps: S301, Regarding array D2 The data

[1000] [0] is used to calculate the small slope, resulting in the small slope SP1[i] = D2[i][0] - D2[i-10][0], which is then stored in the array SP1.

[1000] , where k = 10. S302, Regarding array D2 The data

[1000] [0] is used to calculate the large slope, resulting in the large slope SP2[i] = D2[i][0] - D2[i-30][0], which is then stored in the array SP2.

[1000] , where K = 30. S303, Set the trigger condition TRG1 for the air and electrolyte interface, and adjust array D2.

[1000] [0] Perform sequential inspection from front to back. When TRG1 is triggered, record the row number B of the array, where TRG1 is the result of logical operation including small slope, large slope, array value and time. In this embodiment, the triggering condition for TRG1 is that the small slope SP1[i]>0.15, the large slope SP2[i]>0.3, and i>20 are satisfied simultaneously. S304. Determine the trigger condition TRG2 for the interface between the electrolyte and the aluminum liquid. Continue to inspect the array D2[M][0]. When TRG2 is triggered, record the row number L of the array. TRG2 is the result of a logical operation including small slope, large slope, array value and time. In this embodiment, the triggering condition for TRG2 is that both the small slope SP1[i] < -0.21 and the large slope SP2[i] < -0.5 are satisfied simultaneously. S4, using array S1

[1000] The mass level and aluminum level are calculated, where the mass level height H_BA[0] is 184 mm, the aluminum level height H_AL[0] is 232 mm, and the cathode voltage drop CVD[0] is 250 mV. S5. Determine the rationality of the data of the quality level height H_BA[0], aluminum level height H_AL[0] and cathode voltage drop CVD[0]. If the data is reasonable, output normally. If the data is unreasonable, output H_BA[0] = 1111, H_AL[0] = 1111, CVD[0] = 1111. At this time, manual inspection of the cathode condition of the electrolytic cell is required. In this embodiment, H_BA[0], H_AL[0] and CVD[0] are all within a reasonable range and can be output normally. S6, Extract array D The remaining 47 columns of array

[1000]

[0048] are processed by repeating steps S2-S4 to output the quality level array H_BA

[0048] , the aluminum level array H_AL

[0048] , and the cathode voltage drop array CVD

[0048] . The quality level is the average value of the reasonable data in array H_BA

[0048] , the aluminum level is the average value of the reasonable data in array H_AL

[0048] , and the cathode voltage drop is the average value of the reasonable data in array CVD

[0048] . Example 2: In this embodiment, the voltage drop across two levels and the cathode is measured for a 500kA electrolytic cell. The number of cathode steel rods collected in this embodiment is 12. The calculated CVD[4] data was 90mV, and the output data was 1111. At this time, manual inspection revealed that the cathode was damaged. Other examples are as described in Example 1. Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments; therefore, the claims should be interpreted as including the preferred embodiments as well as various modifications and variations falling within the spirit and scope of the invention, thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents.

Claims

1. A method for calculating the voltage drop at both levels and the cathode of an aluminum electrolytic cell, comprising the following steps: S1. Based on the electrolyte temperature of the aluminum electrolysis cell, the two levels and the pressure drop at the bottom of the furnace, use an online measurement system to collect voltage signal data and store it in array D[M][N], and collect displacement signal data and store it in array S[M]. S2. Extract the first column of array D[M][N], array D[M][0]. Perform data preprocessing on array D[M][0] and array S[M] to obtain array D1[M][0] and array S1[M]. Then, use a filtering algorithm to filter array D1[M][0] to obtain the filtered array D2[M][0]. S3. Set the trigger condition TRG1 for the air and electrolyte interface and the trigger condition TRG2 for the electrolyte and aluminum liquid interface. Perform sequential inspection on array D2[M][0]. When TRG1 is triggered, record the row number B of the array. When TRG2 is triggered, record the row number L of the array. S4. Calculate the quality level and aluminum level using array S1[M], where the quality level height H_BA[0] = S1[L] - S1[B], the aluminum level height H_AL[0] = DSP - S1[L], DSP is the distance from the probe to the bottom of the electrolytic cell, and the cathode voltage drop CVD[0] = AVE(D2[L][0]: D2[L+C][0]), where the value of C is the set value; S5. Determine the rationality of the data of the quality level height H_BA[0], aluminum level height H_AL[0] and cathode voltage drop CVD[0]. If the data is reasonable, output normally; if the data is unreasonable, output H_BA[0] = 1111, H_AL[0] = 1111, CVD[0] = 1111. S6. Extract the remaining columns from array D[M][N], repeat steps S2-S4, and output the quality level array H_BA[N], aluminum level array H_AL[N], and cathode voltage drop array CVD[N]. The quality level is the average of the reasonable data in array H_BA[N], the aluminum level is the average of the reasonable data in array H_AL[N], and the cathode voltage drop is the average of the reasonable data in array CVD[N].

2. The method for calculating the voltage drop of the two levels and the cathode in an aluminum electrolytic cell according to claim 1, characterized in that: In step S1, M is the number of rows of data collected, and N is a natural number greater than 0 and less than the number of cathode steel rods.

3. The method for calculating the voltage drop of the two levels and the cathode in an aluminum electrolytic cell according to claim 1, characterized in that: In step S2, the preprocessing methods include replacing abnormal data, bridging breakpoints in theoretical data, and using constants to fill in the tail of the array; the filtering methods include amplitude limiting filtering, moving average filtering, median filtering, and weighted average filtering.

4. The method for calculating the voltage drop of the two levels and the cathode in an aluminum electrolytic cell according to claim 1, characterized in that: Step S3 includes the following steps: S301. Calculate the small slope of the data in array D2[M][0] to obtain the small slope SP1[i] = D2[i][0] - D2[ik][0], and store it in array SP1[M], where k is a natural number from 2 to 30; S302. Perform a large slope calculation on the data in array D2[M][0] to obtain the large slope SP2[i] = D2[i][0] - D2[iK][0], and store it in array SP2[M], where K is a natural number from 30 to 200; S303. Set the trigger condition TRG1 for the air and electrolyte interface, and perform sequential inspection of array D2[M][0]. When TRG1 is triggered, record the row number B of the array, where TRG1 is the result of logical operation including small slope, large slope, array value and time. S304. Determine the trigger condition TRG2 for the interface between the electrolyte and the aluminum liquid. Continue to inspect the array D2[M][0]. When TRG2 is triggered, record the row number L of the array. TRG2 is the result of a logical operation including small slope, large slope, array value and time.

5. The method for calculating the voltage drop of the two levels and the cathode of the aluminum electrolytic cell according to claim 1, characterized in that: In step S4, the value of C is a set natural number between 1 and 300.

6. The method for calculating the voltage drop of the two levels and the cathode in an aluminum electrolytic cell according to claim 1, characterized in that: In step S5, for cases where the data outputs are unreasonable, such as H_BA[0] = 1111, H_AL[0] = 1111, and CVD[0] = 1111, manual inspection of the cathode condition of the electrolytic cell is introduced to check whether it is normal.

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