Aluminum electrolysis cell multi-area collaborative aluminum oxide concentration balancing method based on dynamic nested control

Abstract

The invention discloses an aluminum electrolysis cell multi-area collaborative aluminum oxide concentration balancing method based on dynamic nested control, and relates to the technical field of industrial aluminum electrolysis cells, the method comprises the following steps: dividing an aluminum electrolysis cell into a plurality of areas based on the distribution positions of all feeders in the aluminum electrolysis cell; and respectively determining an area resistance parameter upper limit and an area resistance parameter lower limit of each area, and based on the multiple area resistance parameter upper limits and the multiple area resistance parameter lower limits, carrying out feeding control on the aluminum electrolysis cell by utilizing a dynamic nested control principle. According to the application, a method of dynamically nesting reverse stroke charging in a partial region in a whole tank insufficient-excessive charging stroke is adopted, so that automatic homogenization of alumina concentration distribution in an electrolysis production process region is realized.

Description

Technical Field

[0001] The present application relates to the technical field of industrial aluminum electrolysis cells, and in particular to a method for balancing the concentration of aluminum oxide in multiple areas of an aluminum electrolysis cell in a coordinated manner based on dynamic nested control. Background Art

[0002] Driven by the pursuit of investment returns, newly built or renovated electrolytic cells are becoming increasingly larger, primarily with 500-600 kA capacity. The number of anodes reaches 48-56, with 6-8 feeding areas. The cell length has increased to approximately 25 meters, while the width remains around 4 meters. At the same time, to reduce energy loss caused by electrolyte resistance, the inter-electrode spacing has been reduced from 5 cm to approximately 3-4 cm, resulting in a corresponding decrease in electrolyte height and volume, weakening flow capacity. The increase in the number of anodes per unit area, the anode current, and the alumina dissolution rate in the electrolyte have increased the difficulty and requirements of alumina feeding control. It is well known that a uniform distribution of alumina concentration in the electrolytic cell helps improve process stability and achieve higher current efficiency. Therefore, the number of feeding points in large cells has increased to 6-8, with each feeder supplying alumina to 4-8 anodes. However, due to a variety of factors, the alumina concentration distribution in large cells varies significantly, making the control significantly less effective than in smaller cells.

[0003] In particular, the traditional method of controlling the feeding of large electrolytic cells still relies on the cell resistance information estimated from the series current and cell voltage as the basis for feeding. This assumption assumes that the alumina consumption rate is uniform across all feeding zones, leading to the uniform addition of alumina. This is the primary reason for the poor alumina control in large electrolytic cells. The best solution to this problem is to feed the electrolytic cell based on the alumina consumption rate of each zone, i.e., the magnitude of the regional anode current. However, since the alumina concentration cannot be measured online, and the amount of alumina added to the electrolytic cell cannot be accurately controlled under high temperatures, strong magnetic fields, and highly corrosive environments, the classic underfeeding-overfeeding strategy is still used to control the alumina concentration in each zone within the range of 1.5-3.5%. Specifically, the electrolytic cell is divided into multiple zones with the feeder as the geometric center. The alumina feeding operation is controlled based on the RC curve of resistance-concentration changes: an underfeeding (UF)-overfeeding (OF) strategy is adopted to control the alumina concentration within a specified [Cd, Cu] range. Underdosing occurs when the amount of alumina added each time is less than the theoretical consumption of the series current, resulting in a decreasing alumina concentration in the electrolyte and a shift in resistance toward increasing levels. Overdosing occurs when the amount of alumina added each time exceeds the theoretical consumption of the series current, resulting in a continuously increasing alumina concentration and a shift in resistance toward decreasing levels. To maintain a minimum alumina concentration of no less than Cd and no more than Cu, the electrolyte resistance must be controlled to a maximum of Ru and a minimum of Rd. In theory, adding alumina at a rate determined by the regional anode current can maintain a uniform concentration distribution across the electrolytic cell. However, in actual production, the amount of alumina added to the electrolyte by each feeder may not be the same. In particular, the alumina concentration in the cell can vary significantly between zones due to operations such as pole changing, leading to significant differences in concentration between zones. This can create challenges for simple on-demand dosing control. Summary of the Invention

[0004] The purpose of this application is to provide a method for balancing the alumina concentration in multiple areas of an aluminum electrolytic cell based on dynamic nested control, which adopts a method of dynamically nesting the reverse feeding of some areas in the under-feeding-overfeeding stroke of the entire cell to achieve automatic homogenization of the alumina concentration distribution in the electrolytic production process.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] The present application provides a method for balancing alumina concentration in multiple zones of an aluminum electrolysis cell based on dynamic nested control, comprising:

[0007] The aluminum electrolysis cell is divided into a plurality of areas based on the distribution positions of all feeders in the aluminum electrolysis cell; the areas correspond to the feeders one by one; and the feeders are located at the geometric center of the corresponding areas;

[0008] Obtaining an upper limit and a lower limit of a cell resistance parameter; the upper limit and the lower limit of the cell resistance parameter are read from a resistance-alumina concentration relationship curve of the aluminum electrolysis cell;

[0009] Obtaining an upper limit and a lower limit of a regional resistance parameter; the upper limit and the lower limit of the regional resistance parameter are read from a resistance-alumina concentration relationship curve of the aluminum electrolysis cell region;

[0010] Based on the plurality of upper limits of the regional resistance parameters and the plurality of lower limits of the regional resistance parameters, the feeding of the aluminum electrolysis cell is controlled.

[0011] Optionally, controlling the feeding of the aluminum electrolysis cell based on a plurality of upper limits of the regional resistance parameters and a plurality of lower limits of the regional resistance parameters includes:

[0012] Obtain the regional anode current of each zone in the aluminum electrolysis cell;

[0013] Based on the anode currents of the plurality of regions, the regional theoretical consumption rate of each region in the aluminum electrolytic cell is determined using a regional theoretical consumption rate formula;

[0014] Based on the upper limits of the resistance parameters of the multiple regions, the lower limits of the resistance parameters of the multiple regions and the theoretical consumption rates of the multiple regions, the feeding of the aluminum electrolytic cell is controlled by using the dynamic nested control principle.

[0015] Optionally, the theoretical consumption rate of the region is:

[0016]

[0017] in, is the theoretical consumption rate of the region corresponding to the jth region; q is the electrochemical equivalent of aluminum oxide, which is a constant; I j is the regional anode current corresponding to the jth region, and η is the current efficiency.

[0018] Optionally, the dynamic nesting control principle is:

[0019] All areas in the aluminum electrolytic cell are under-dosing controlled;

[0020] Counting the number of areas that meet the overfeeding conversion condition as the first number;

[0021] When the first number is less than the whole tank conversion threshold, overfeeding control is performed on the areas that meet the overfeeding conversion conditions, and underfeeding control is performed on the areas that do not meet the overfeeding conversion conditions, and the process returns to step "counting the number of areas that meet the overfeeding conversion conditions as the first number";

[0022] When the first amount is greater than or equal to the whole cell conversion threshold, all areas of the aluminum electrolysis cell are subjected to overfeed control;

[0023] The number of areas meeting the insufficient blanking conversion condition is counted as the second number;

[0024] When the second number is less than the whole tank conversion threshold, the under-feeding control is performed on the areas that meet the under-feeding conversion conditions, and the over-feeding control is performed on the areas that do not meet the under-feeding conversion conditions, and the process returns to step "counting the number of areas that meet the under-feeding conversion conditions as the second number";

[0025] When the second quantity is greater than or equal to the whole cell conversion threshold, return to step "performing under-feeding control on all areas in the aluminum electrolysis cell".

[0026] Optionally, the overfeed conversion condition is that the real-time regional resistance of the region is greater than the upper limit of the regional resistance parameter.

[0027] Optionally, the whole-cell conversion threshold is half of the total number of zones in the aluminum electrolysis cell.

[0028] Optionally, the under-feeding conversion condition is that the real-time regional resistance of the region is less than the lower limit of the regional resistance parameter.

[0029] Optionally, the current area is controlled to be under-feeding according to the under-feeding speed of the current area; the current area is any area in the aluminum electrolysis cell;

[0030] The overfeeding control is performed on the current area according to the regional overfeeding speed of the current area.

[0031] Optionally, the regional under-feeding speed of the current region is the product of the under-feeding coefficient and the regional theoretical consumption speed of the current region; the under-feeding coefficient is greater than 0; and the under-feeding coefficient is less than 1;

[0032] The regional excess feeding rate of the current region is the product of the excess coefficient and the regional theoretical consumption rate of the current region; the excess coefficient is greater than 1; and the excess coefficient is less than 2.

[0033] Optionally, the dynamic nesting control principle is:

[0034] Obtain the target concentration of alumina in the entire tank;

[0035] Get the real-time regional resistance of each zone in the aluminum electrolysis cell;

[0036] Determining the real-time regional alumina concentration of each region in the aluminum electrolysis cell based on the resistance-alumina concentration relationship curve;

[0037] For the area where the real-time regional alumina concentration is lower than the target alumina concentration of the entire tank, regional circulation excess feeding control is performed;

[0038] For the area where the real-time alumina concentration is higher than the target alumina concentration of the whole tank, regional circulation under-feeding control is performed;

[0039] For the area where the real-time alumina concentration is equal to the target alumina concentration of the entire tank, the feeding is controlled according to the theoretical consumption rate of the area.

[0040] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0041] The present application provides a method for balancing the concentration of alumina in multiple areas of an aluminum electrolytic cell in a coordinated manner based on dynamic nested control. The method determines the upper limit and lower limit of the regional parameters of each area in the industrial aluminum electrolytic cell according to the cell resistance-alumina concentration relationship curve, the cell voltage and series current, and the regional anode current of each area in the industrial aluminum electrolytic cell, thereby realizing the nested feeding control of the industrial aluminum electrolytic cell. The strategy of over-feeding some areas under the under-feeding stroke of the entire cell and under-feeding some areas under the over-feeding stroke of the entire cell is adopted. During the alternating cycle of under-feeding and over-feeding, the alumina concentration is ensured to automatically tend to be uniformly distributed while varying within the target range of 1.5% to 3.5%, thereby improving the uniformity of the alumina concentration in the electrolytic cell, improving the electrolytic production efficiency, realizing green and energy-saving production of the aluminum electrolytic cell, and reducing costs and increasing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 This is a flow chart of a method for balancing the concentration of aluminum oxide in multiple zones of an aluminum electrolysis cell based on dynamic nested control in one embodiment of the present application;

[0044] Figure 2 This is a diagram of the feeder-anode layout of an electrolytic cell with 4 feeding ports and 36 anodes in one embodiment of the present application;

[0045] Figure 3A graph showing the relationship between resistance and alumina concentration used for controlling alumina feeding in an embodiment of the present application;

[0046] Figure 4 This is a dynamic nested control flow chart in an embodiment of the present application;

[0047] Figure 5 This is a flow chart of a special implementation method of dynamic nested control in one embodiment of the present application. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0049] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0050] In an exemplary embodiment, Figure 1 As shown, a method for balancing the concentration of alumina in multiple zones of an aluminum electrolytic cell based on dynamic nested control is provided, comprising:

[0051] Step 101: Divide the aluminum electrolysis cell into multiple zones based on the distribution of all feeders in the cell. Each zone corresponds to a feeder on a one-to-one basis. The feeder is located at the geometric center of the corresponding zone.

[0052] Feeder-anode layout diagram Figure 2 As shown, each feeder in the area indicated by the dotted line supplies alumina to 4 to 10 anodes in this area. Feed port 1 and feed port 4 feed 10 anodes respectively, while feed port 2 and feed port 3 only feed 8 anodes respectively. That is to say, the area corresponding to feed port 1 and the area corresponding to feed port 4 include 10 anodes, while the area corresponding to feed port 2 and the area corresponding to feed port 3 only include 8 anodes. A01, A02, A17 and A18 are all A-side anodes; B01, B02, B17 and B18 are all B-side anodes. The alumina feeding in each area is independently controlled, and the control is based on the anode current of the area and the regional resistance change rate. For Figure 2 The case where each region includes different anodes, that is, n=4, m T =36, m1=m4=10, m3=m4=8. According to this authorization, the alumina feeding of the four regions is independently controlled. Specifically, for region j, the feeding amount is determined by the current I jThe aluminum oxide concentration in the area is determined and controlled in the manner of under-feeding stroke-over-feeding stroke to be within a range of 1.5-3.5%, or even narrower.

[0053] Step 102: Obtaining the upper limit and lower limit of the cell resistance parameter. The upper limit and lower limit of the cell resistance parameter are read from the resistance-alumina concentration relationship curve of the aluminum electrolysis cell.

[0054] Step 103: Obtaining the upper limit and lower limit of the regional resistance parameter. The upper limit and lower limit of the regional resistance parameter are read from the resistance-aluminum oxide concentration relationship curve of the aluminum electrolysis cell area.

[0055] The resistance-alumina concentration relationship curve of the aluminum electrolytic cell is as follows: Figure 3 shown. Figure 3 The middle resistance represents the slot resistance and also represents the regional resistance. The two have similar characteristics but different values. The strategy of underfeeding (UF)-overfeeding (OF) is adopted to control the alumina resistance at the specified [C d , C u The so-called under-dosing means that the amount of alumina added each time is lower than the theoretical consumption of the series current, which causes the concentration of alumina in the electrolyte to become lower and lower, and the resistance to change in the direction of increasing. Figure 3 The direction indicated by the arrow UF in the figure; the so-called over-feeding means that the amount of alumina added each time is higher than the theoretical consumption of the series current, which causes the concentration of alumina in the electrolyte to become higher and higher, and the resistance to change in the direction of lower and lower, that is, Figure 3 The direction indicated by the OF arrow. In order to make the aluminum oxide concentration not less than C d , the maximum does not exceed C u , correspondingly, the maximum electrolyte resistance should be controlled not to exceed the upper resistance limit R u , the minimum resistance does not exceed the lower limit R d .

[0056] Step 104: Based on the upper limits of the multiple regional resistance parameters and the lower limits of the multiple regional resistance parameters, controlling the feeding of the aluminum electrolysis cell.

[0057] Based on multiple regional resistance parameter upper limits and multiple regional resistance parameter lower limits, the aluminum electrolytic cell is controlled by feeding the material, including: obtaining the regional anode current of each region in the aluminum electrolytic cell. Based on the multiple regional anode currents, the regional theoretical consumption rate of each region in the aluminum electrolytic cell is determined using a regional theoretical consumption rate formula. Based on the multiple regional resistance parameter upper limits, multiple regional resistance parameter lower limits, and multiple regional theoretical consumption rates, the aluminum electrolytic cell is controlled by a dynamic nested control principle. The regional theoretical consumption rate is: in, is the theoretical consumption rate of the region corresponding to the jth region. q is the electrochemical equivalent of aluminum oxide, which is a constant. j is the regional anode current corresponding to the jth region, and η is the current efficiency.

[0058] The entire electrolytic cell is fed with raw alumina in an alternating under- and over-dosing cycle to achieve electrolytic production, controlling the alumina concentration within the target range of 1.5-3.5%. During the under-dosing cycle, some areas can be switched to over-dosing; during the over-dosing cycle, some areas can be switched to under-dosing, thereby achieving a uniform distribution of alumina concentration across the cell. The electrolytic cell is divided into corresponding zones with the feed port as the geometric center. The anode current of each zone is precisely measured, and the alumina feed rate for each zone is determined by the anode current of the zone. Single-point, on-demand independent feeding is implemented, and the zones of the electrolytic cell are fed in an alternating under- and over-dosing cycle. Under-dosing refers to a zone where the rate of alumina addition is lower than the rate of alumina consumption, while over-dosing refers to a zone where the rate of alumina addition is higher than the rate of alumina consumption. Whole-cell underfeeding refers to the addition of alumina to all or most areas of the electrolytic cell, causing the alumina concentration in the entire cell to decrease. Whole-cell overfeeding refers to the addition of alumina to all or most areas of the electrolytic cell, causing the alumina concentration in the entire cell to increase. During the whole-cell underfeeding process, the changes in the electrolytic cell resistance parameters are tracked in real time. When the cell resistance parameter exceeds the set cell resistance parameter upper limit, the electrolytic cell is controlled to enter the whole-cell overfeeding process. During the whole-cell overfeeding process, the changes in the electrolytic cell resistance parameters are tracked in real time. When the cell resistance parameter exceeds the set cell resistance parameter lower limit, the electrolytic cell is controlled to enter the underfeeding process. During the under-feeding stroke of the entire cell, the changes in the resistance parameters of all areas of the electrolytic cell are tracked in real time. When the cell resistance parameters do not exceed the set upper limit of the cell resistance parameters: when the regional resistance parameters of all areas are less than the set upper limit of the regional resistance parameters of the corresponding areas, all areas will perform under-feeding stroke; when the regional resistance parameters of less than half of the areas are greater than the set upper limit of the regional resistance parameters of the corresponding areas, these areas will be controlled to switch to over-feeding stroke, and other areas will continue to use under-feeding stroke; when the regional resistance parameters of more than half of the areas are greater than the set upper limit of the regional resistance parameters of the corresponding areas, the entire cell will switch to over-feeding stroke. During the overfeeding stroke of the entire cell, the changes in the resistance parameters of all areas of the electrolytic cell are tracked in real time. When the cell resistance parameter does not exceed the set lower limit of the cell resistance parameter: when the regional resistance parameters of all areas are greater than the set lower limit of the regional resistance parameter of the corresponding area, all areas will perform overfeeding; when the regional resistance parameters of less than half of the areas are less than the set lower limit of the regional resistance parameter of the corresponding area, these areas will be controlled to enter the underfeeding stroke, and other areas will continue to use the overfeeding stroke; when the regional resistance parameters of more than half of the areas are less than the set lower limit of the regional resistance parameter of the corresponding area, the entire cell will enter the underfeeding stroke.

[0059] The dynamic nesting control principle is:

[0060] Step 1: Perform under-feeding control on all areas in the aluminum electrolysis cell. Perform under-feeding control on the current area according to the under-feeding speed of the current area.

[0061] Step 2: Count the number of areas that meet the overfeeding conversion condition as the first number.

[0062] Step 3: When the first quantity is less than the entire tank conversion threshold, overfeeding control is performed for all areas that meet the overfeeding conversion conditions, and underfeeding control is performed for all areas that do not meet the overfeeding conversion conditions, and the process returns to Step 2. The overfeeding conversion condition is that the real-time regional resistance of the area is greater than the upper limit of the regional resistance parameter.

[0063] Step 4: When the first quantity is greater than or equal to the whole cell conversion threshold, overfeeding control is performed on all zones in the aluminum electrolysis cell. The whole cell conversion threshold is half of the total number of zones in the aluminum electrolysis cell.

[0064] Step 5: Count the number of areas that meet the under-cutting conversion conditions as the second number.

[0065] Step 6: When the second quantity is less than the entire tank conversion threshold, underfeed control is performed for all zones that meet the underfeed conversion conditions, and overfeed control is performed for all zones that do not meet the underfeed conversion conditions, and the process returns to Step 5. The underfeed conversion condition is that the zone's real-time regional resistance is less than the lower limit of the regional resistance parameter. Overfeed control is performed for the current zone based on the current zone's regional overfeed rate. The current zone's regional overfeed rate is the product of the overfeed coefficient and the current zone's theoretical regional consumption rate.

[0066] The current area is any area in the aluminum electrolysis cell.

[0067] The regional under-feeding rate for the current area is the product of the under-feeding coefficient and the theoretical consumption rate for the current area. The under-feeding coefficient is greater than 0 and less than 1.

[0068] The regional under-feeding speed of the current area is:

[0069]

[0070] in, is the underfeeding speed of the jth region; α is the underfeeding coefficient.

[0071] The regional excess feeding rate of the current region is the product of the excess coefficient and the regional theoretical consumption rate of the current region. The excess coefficient is greater than 1.

[0072] The regional overfeed rate for the current region is:

[0073]

[0074] in, is the regional excess feeding rate of the jth region; β is the excess coefficient.

[0075] like Figure 4 ,The dynamic nested control principle specifically includes the following steps.

[0076] A: The electrolytic cell is in the process of short-feeding the entire cell. Short-feeding the entire cell means that the rate of alumina addition in all or part of the area is lower than the theoretical consumption rate of alumina in the area, causing the alumina concentration in the entire cell to decrease. Among them:

[0077] A1: Add alumina in the area according to the under-measurement stroke.

[0078] A2: Regional alumina is added according to the excess stroke.

[0079] B: Determine the real-time cell resistance and the real-time zone resistance for each zone based on the cell voltage, series current, and multiple zone anode currents.

[0080] C1: Determine whether the electrolytic cell has excessive material conversion in the entire cell, and obtain a first judgment result; if there is excessive material conversion, the real-time cell resistance is greater than or equal to the upper limit of the cell resistance parameter.

[0081] If the first judgment result is yes, the feeding mode of the corresponding feeding ports in all areas of the industrial aluminum electrolytic cell is updated to overfeeding, and the entire cell enters the overfeeding stroke D.

[0082] If the first judgment result is no, then:

[0083] C2: Determine whether there is excessive conversion in each area, and obtain a second judgment result; the existence of an excessive conversion area means that the resistance of the area is greater than or equal to the upper limit of the resistance parameter of the corresponding area.

[0084] If the second determination result of a certain area is negative, the process proceeds to step A1.

[0085] If the second determination result of a certain area is yes, the process proceeds to step C3.

[0086] C3: Determine whether the number of regions with excessive conversion reaches or exceeds half of the number of regions in the electrolytic cell, and obtain a third determination result.

[0087] If the third judgment result is no, then transfer to step A2.

[0088] If the third judgment result is yes, then transfer to step D.

[0089] D: The electrolytic cell is in the process of over-feeding the entire cell. Over-feeding the entire cell means that the rate of alumina addition in all or part of the area is greater than the theoretical consumption rate of alumina in the area, causing the alumina concentration in the entire cell to increase.

[0090] D1: The area is filled according to the excess stroke.

[0091] D2: Add material to the area according to the under-measurement stroke.

[0092] E: Determine the real-time cell resistance and the real-time zone resistance for each zone based on the cell voltage, series current, and multiple zone anode currents.

[0093] F1: Determine whether the electrolytic cell has insufficient feeding conversion, and obtain a fourth judgment result; if insufficient feeding conversion exists, the real-time cell resistance is less than or equal to the lower limit of the cell resistance parameter;

[0094] If the fourth judgment result is yes, the feeding mode of the corresponding feeding ports in all areas of the industrial aluminum electrolytic cell will be updated to under-feeding, and the entire cell will enter under-feeding stroke A.

[0095] If the fourth judgment result is no, then:

[0096] F2: Determine whether there is insufficient material conversion in each area, and obtain the fifth judgment result; the existence of insufficient conversion area means that the resistance of the area is less than or equal to the lower limit of the resistance parameter of the corresponding area.

[0097] If the fifth determination result of a certain area is negative, the process proceeds to step D1 .

[0098] If the fifth determination result of a certain area is yes, the process proceeds to step F3.

[0099] F3: Determine whether the number of areas with insufficient conversion reaches or exceeds half of the number of areas in the electrolytic cell, and obtain a sixth determination result. Figure 4 Where s represents the number of regions with underconversion or the number of regions with overconversion; s0 is half the number of electrolytic cell regions.

[0100] If the sixth judgment result is no, the process proceeds to step D2.

[0101] If the sixth judgment result is yes, proceed to step A.

[0102] To achieve the above control objectives, the method of alternately circulating under-feeding stroke and over-feeding stroke is used to control the alumina feeding speed, so that the tank resistance R cell At an upper limit and lower limit changes within the target range, so that Real-time tracking of cell resistance R during electrolysis cell; When the under-feeding stroke is in progress, the slot resistance R cell Continuously increase, when it is equal to or greater than the set upper limit Right now Then it switches to the overfeeding stroke, in which the slot resistance R cell Continuously decrease, when it is equal to or less than Then it switches to the under-feeding stroke.

[0103] Special cases of dynamic nesting control principle such as Figure 5 As shown: Obtain the target alumina concentration for the entire cell. Obtain the real-time regional resistance of each zone in the aluminum electrolysis cell. Determine the real-time regional alumina concentration for each zone in the aluminum electrolysis cell based on the resistance-alumina concentration curve. Perform regional circulation overfeeding control for zones where the real-time regional alumina concentration is lower than the target alumina concentration for the entire cell. Perform regional circulation underfeeding control for zones where the real-time regional alumina concentration is higher than the target alumina concentration for the entire cell. Perform feeding control based on the theoretical regional consumption rate for zones where the real-time regional alumina concentration is equal to the target alumina concentration for the entire cell.

[0104] Since the alumina concentration in the aluminum electrolytic cell cannot be measured in real time, the current existing technologies are based on the resistance-concentration curve, by real-time collection of the electrolytic cell resistance, and by under-dosing and over-dosing the entire cell to allow the alumina concentration to fluctuate within the range of 1.5 to 3.5%, in order to determine and control the range of alumina. Due to the high and low fluctuations in concentration, the control efficiency is not optimized. The electrolytic cell is divided into m areas, and the corresponding regional resistance is measured and calculated in real time for each area, and the alumina feeding amount of each area can be independently controlled by under-dosing and over-dosing. Therefore, when it is determined that the alumina concentration of the entire cell needs to be controlled at a fixed value (such as 2.5%): 1) By unloading on demand based on the regional current, the alumina concentration in each area of the entire cell is guaranteed to be stable under normal circumstances. 2) When the alumina concentration in some areas is too high or too low due to the pole-changing operation or feeder failure in electrolytic production: (1) If the regional concentration is lower than the set value, the alumina concentration in the area will be automatically increased to the set value by the regional circulation overfeeding method; (2) If the regional concentration is higher than the set value, the alumina concentration in the area will be automatically reduced to the set value by the regional circulation underfeeding method; (3) The theoretical feeding method is used to maintain the original concentration in other areas.

[0105] In this way, the alumina concentration can be set at an optimal concentration value or an optimal narrow range to achieve optimized feeding. Figure 5 Middle R * j Set the regional resistance value corresponding to the target concentration for region j and the entire cell.

[0106] The present application achieves uniform alumina concentration in various areas of the electrolytic cell through automatic feeding adjustment by overfeeding some areas during the entire cell underfeeding process, and underfeeding some areas during the entire cell overfeeding process. The principle is that during the entire cell underfeeding process, the alumina concentration in the entire cell and in each area gradually decreases; as the feeding process progresses, the area with the lowest alumina concentration reaches its set lower concentration limit first, and this area switches to overfeeding. As the alumina concentration in the entire cell gradually decreases, the alumina concentration in this area gradually increases and approaches the average value; other low-concentration areas are also fed in this way, thereby relatively increasing the alumina concentration in each low-concentration area and reducing the concentration difference between areas. Similarly, during the overfeeding process of the entire tank, the alumina concentration of the entire tank and each area gradually increases; as the overfeeding process proceeds, the area with the highest alumina concentration first reaches its set concentration upper limit, and this area switches to underfeeding. As the alumina concentration of the entire tank gradually increases, the alumina concentration of this area gradually decreases and approaches the average value; other high-concentration areas are also unloaded in this way, thereby relatively reducing the alumina concentration of each high-concentration area and reducing the concentration difference between areas. By embedding the overfeeding process of the low-concentration area in the underfeeding process of the entire tank, and the underfeeding process of the high-concentration area in the overfeeding process of the entire tank, the consistency of the alumina concentration in each area of the electrolytic cell is automatically driven, the uniformity of the alumina concentration in the industrial aluminum electrolytic cell is improved, the probability of the anode effect of the electrolytic cell is reduced, precipitation is reduced, the current efficiency is improved, and high-efficiency, energy-saving and low-carbon production is achieved.

[0107] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for balancing the concentration of alumina in multiple zones of an aluminum electrolytic cell based on dynamic nested control, characterized in that: include: Dividing the aluminum electrolysis cell into a plurality of areas based on the distribution positions of all feeders in the aluminum electrolysis cell; The areas correspond to the feeders one by one; the feeders are located at the geometric center of the corresponding areas; Obtaining an upper limit and a lower limit of a cell resistance parameter; the upper limit and the lower limit of the cell resistance parameter are read from a resistance-alumina concentration relationship curve of the aluminum electrolysis cell; Get the upper limit and lower limit of regional resistance parameters; The upper limit of the regional resistance parameter and the lower limit of the regional resistance parameter are read from the resistance-aluminum oxide concentration relationship curve of the aluminum electrolysis cell area; Based on the plurality of upper limits of the regional resistance parameters and the plurality of lower limits of the regional resistance parameters, the feeding of the aluminum electrolysis cell is controlled.

2. The method for balancing alumina concentration in multiple zones of an aluminum electrolysis cell based on dynamic nested control according to claim 1, characterized in that: Based on the plurality of upper limits of the regional resistance parameters and the plurality of lower limits of the regional resistance parameters, the aluminum electrolysis cell is controlled to be charged, including: Obtain the regional anode current of each zone in the aluminum electrolysis cell; Based on the anode currents of the plurality of regions, the regional theoretical consumption rate of each region in the aluminum electrolytic cell is determined using a regional theoretical consumption rate formula; Based on the upper limits of the resistance parameters of the multiple regions, the lower limits of the resistance parameters of the multiple regions and the theoretical consumption rates of the multiple regions, the feeding of the aluminum electrolytic cell is controlled by using the dynamic nested control principle.

3. The method for balancing alumina concentration in multiple zones of an aluminum electrolysis cell based on dynamic nested control according to claim 2, characterized in that: The theoretical consumption rate of the region is: in, is the theoretical consumption rate of the region corresponding to the jth region; q is the electrochemical equivalent of aluminum oxide, which is a constant; I j is the regional anode current corresponding to the jth region, and η is the current efficiency.

4. The method for balancing alumina concentration in multiple zones of an aluminum electrolysis cell based on dynamic nested control according to claim 2, characterized in that: The dynamic nesting control principle is: All areas in the aluminum electrolytic cell are under-dosing controlled; Counting the number of areas that meet the overfeeding conversion condition as the first number; When the first number is less than the whole tank conversion threshold, overfeeding control is performed on the areas that meet the overfeeding conversion condition, and underfeeding control is performed on the areas that do not meet the overfeeding conversion condition, and the process returns to step "counting the number of areas that meet the overfeeding conversion condition as the first number"; When the first amount is greater than or equal to the whole cell conversion threshold, all areas of the aluminum electrolysis cell are subjected to overfeed control; The number of areas meeting the insufficient blanking conversion condition is counted as the second number; When the second number is less than the whole tank conversion threshold, the under-feeding control is performed on the areas that meet the under-feeding conversion conditions, and the over-feeding control is performed on the areas that do not meet the under-feeding conversion conditions, and the process returns to step "counting the number of areas that meet the under-feeding conversion conditions as the second number"; When the second quantity is greater than or equal to the whole cell conversion threshold, return to step "performing under-feeding control on all areas in the aluminum electrolysis cell".

5. The method for balancing alumina concentration in multiple zones of an aluminum electrolysis cell based on dynamic nested control according to claim 4, characterized in that: The overfeeding conversion condition is that the real-time regional resistance of the region is greater than the upper limit of the regional resistance parameter.

6. The method for balancing alumina concentration in multiple zones of an aluminum electrolysis cell based on dynamic nested control according to claim 4, characterized in that: The whole cell conversion threshold is half of the total number of zones in the aluminum electrolysis cell.

7. The method for balancing alumina concentration in multiple zones of an aluminum electrolysis cell based on dynamic nested control according to claim 4, characterized in that: The under-feeding conversion condition is that the real-time regional resistance of the region is less than the lower limit of the regional resistance parameter.

8. The method for balancing alumina concentration in multiple zones of an aluminum electrolysis cell based on dynamic nested control according to claim 4, characterized in that: Performing under-feeding control on the current area according to the under-feeding speed of the current area; the current area is any area in the aluminum electrolysis cell; The overfeeding control is performed on the current area according to the regional overfeeding speed of the current area.

9. The method for balancing alumina concentration in multiple zones of an aluminum electrolysis cell based on dynamic nested control according to claim 8, characterized in that: The regional under-feeding speed of the current region is the product of the under-feeding coefficient and the regional theoretical consumption speed of the current region; the under-feeding coefficient is greater than 0; and the under-feeding coefficient is less than 1; The regional excess feeding rate of the current region is the product of the excess coefficient and the regional theoretical consumption rate of the current region; the excess coefficient is greater than 1; and the excess coefficient is less than 2.

10. The method for balancing alumina concentration in multiple zones of an aluminum electrolysis cell based on dynamic nested control according to claim 2, characterized in that: The dynamic nesting control principle is: Obtain the target concentration of alumina in the entire tank; Get the real-time regional resistance of each zone in the aluminum electrolysis cell; Determining the real-time regional alumina concentration of each region in the aluminum electrolysis cell based on the resistance-alumina concentration relationship curve; For a region where the real-time alumina concentration is lower than the target alumina concentration of the entire tank, regional circulation excess feeding control is performed; For the area where the real-time alumina concentration is higher than the target alumina concentration of the whole tank, regional circulation under-feeding control is performed; For the area where the real-time alumina concentration is equal to the target alumina concentration of the entire tank, the feeding is controlled according to the theoretical consumption rate of the area.

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