Method and system for automatic distribution of current during baking period of an aluminum electrolytic cell

Abstract

The application discloses a kind of aluminum electrolytic cell baking period current automatic distribution method and system thereof, the current feedback signal of temperature data and current detection table is collected by temperature element, central control computer is combined with baking process algorithm, preset temperature-current curve model, automatically adjust the on-off state of each shunt branch, realize the dynamic precision control of baking current, to avoid the waterfall type cliff phenomenon when current reduces, ensure that baking tank completes baking according to preset temperature curve;The application can accurately control the baking current, ensure that the electrolytic cell completes baking according to the preset temperature curve, completely solve the problems of uneven current distribution, difficult to control the temperature gradient, high operation risk and other problems existing in traditional manual shunt mode, significantly improve the baking quality of electrolytic cell, prolong the service life of electrolytic cell, while reducing labor cost and safety hazard.

Description

Technical Field

[0001] This invention relates to a method and system for automatic current distribution during the roasting period of an aluminum electrolytic cell, belonging to the technical field of current distribution during the roasting period of an aluminum electrolytic cell. Background Technology

[0002] Traditional aluminum electrolysis cell roasting current shunting methods use copper or steel shunt strips as the core conductors, which are fixed between the roasting cell's balance busbar and the downstream cell's column busbar using clamps to achieve current shunting. To prevent the copper or steel shunt strips from burning out due to overheating, insulating high-temperature resistant materials (such as electrolytes) must be filled between the shunt strips for heat insulation. In some scenarios, mechanical air cooling is also required for auxiliary cooling. This current shunting method has several prominent drawbacks, as follows: First, labor costs are high: dedicated personnel are required to be on duty throughout the process, performing operations such as blowing air to cool the equipment in real time, resulting in high labor intensity for the workers. Second, current control accuracy is low: the shunt plate can only be removed as a whole, and it is impossible to make precise step-by-step control of the current, which can easily lead to uneven distribution of anode current, causing the cathode temperature gradient to deviate from the process requirements, directly affecting the roasting quality and the service life of the electrolytic cell. Third, safety risks are high: when removing the shunt plate, the workers need to be in close contact with high-temperature equipment, posing safety hazards such as burns and electric shocks. Fourth, operating costs are high: copper or steel shunt plates are prone to damage due to overheating, and the shunt material itself is expensive, resulting in high costs in the long term.

[0003] At the same time, existing current shunting technologies suffer from low automation. During the current shunting process, a waterfall-like drop occurs when the current decreases. The core reason is that these technologies regulate the current by directly disconnecting the contact points, requiring manual assistance such as temperature measurement. In the early stages, multiple contact points were in full contact. When the current needed to be reduced, disconnecting just one contact point would cause the current to drop instantly, making it impossible to achieve uniform and stable regulation.

[0004] Therefore, there is a need for a method and system for automatic current distribution during the roasting period of aluminum electrolytic cells, which can accurately control the roasting current and ensure that the electrolytic cells complete roasting according to a preset temperature curve. This can completely solve the problems of uneven current distribution, difficulty in controlling the temperature gradient, and high operational risks associated with traditional manual current distribution methods, significantly improve the roasting quality of electrolytic cells, extend the service life of electrolytic cells, and reduce labor costs and safety hazards. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method and system for automatic current distribution during the roasting period of an aluminum electrolytic cell, which can accurately control the roasting current and ensure that the electrolytic cell completes roasting according to a preset temperature curve. This can completely solve the problems of uneven current distribution, difficulty in controlling the temperature gradient, and high operational risks that exist in traditional manual current distribution methods, significantly improve the roasting quality of the electrolytic cell, extend the service life of the electrolytic cell, and reduce labor costs and safety hazards; it can overcome the shortcomings of the prior art.

[0006] The objective of this invention is achieved through the following technical solution: This invention discloses a method for automatic current distribution during the roasting period of an aluminum electrolytic cell. The method uses temperature data from a temperature acquisition element and current feedback signal from a current detection meter. The central control computer combines the roasting process algorithm and preset a temperature-current curve model to automatically adjust the on / off state of each branch circuit, thereby achieving dynamic and precise control of the roasting current. This avoids the waterfall-like drop phenomenon when the current decreases, ensuring that the roasting cell (1) completes roasting according to the preset temperature curve.

[0007] The above-mentioned relationship between the enhanced current, tank temperature change, and required current for roasting in this roasting process algorithm is as follows: .

[0008] The above: .

[0009] This system for automatic current distribution during the roasting period of an aluminum electrolysis cell includes a roasting cell, a downstream cell, a temperature acquisition element, a shorting wire, an adjustable shunt, a current meter, a relay converter, and a central control computer. Specifically, a downstream cell is located adjacent to the roasting cell; the temperature acquisition element is positioned at the corresponding position on the column busbar within the roasting cell; the shorting wire connects the horizontal busbar of the roasting cell and the column busbar of the downstream cell, serving as a current branch; the adjustable shunt is connected in series with the shorting wire to linearly adjust the current output from the horizontal busbar of the roasting cell to the downstream cell, thereby indirectly controlling the current value entering the roasting cell and achieving stable temperature rise in the roasting cell; the current meter is integrated inside the adjustable shunt to monitor the current parameters of the current branch in real time; the relay converter converts the analog signal output by the temperature acquisition element into a standard industrial signal; the central control computer collects the temperature signal output by the relay converter and the current data from the current meter in real time, and controls the adjustable shunt to perform current adjustment operations according to preset control logic.

[0010] The temperature acquisition element mentioned above is an armored thermocouple, which is located in the contact area between the anode carbon block and the molten aluminum.

[0011] The aforementioned adjustable shunt includes a housing, a variable resistance alloy shunt, contact points, a cooling device, a reciprocating pneumatic device, and an air compressor. Specifically, the housing is connected in series with a jumper wire to house the various components of the shunt. One end of the variable resistance alloy shunt is connected to a jumper wire leading to the downstream tank, and its surface is provided with a slidable contact point, which is connected to the input jumper wire connecting the horizontal busbar. The contact point can slide from one end of the variable resistance alloy shunt to the other, changing the resistance value on the shunt branch and thus adjusting the shunt current. The cooling device is located inside the housing to provide real-time cooling for the variable resistance alloy shunt, preventing it from being damaged due to overheating. The reciprocating pneumatic device is connected to the contact point and drives the contact point to slide back and forth along the variable resistance alloy shunt. The reciprocating pneumatic device is connected to the air compressor or the shell-breaking system installed on the electrolytic cell to obtain pneumatic power.

[0012] The aforementioned variable resistance alloy shunt is made of copper-aluminum alloy and has an oxide film on its surface.

[0013] The aforementioned shorting wire is equipped with a smart circuit breaker connected in series to realize overload and short circuit protection and on / off control of the branch circuit.

[0014] As mentioned above, the short-connector is connected to the horizontal busbar of the roasting tank and the column busbar of the downstream tank respectively through adjustable clamps.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention utilizes a built-in roasting process control algorithm in the central control computer. The controller receives temperature data from the temperature acquisition element and current feedback signals from the current detection meter. Through a preset temperature-current curve model, it automatically adjusts the on / off state of each branch circuit to achieve dynamic and precise control of the roasting current.

[0016] 2. To avoid the pneumatic power of the air compressor or shell-breaking system being affected by the magnetic field, the current magnitude can be controlled by adjusting the resistance of the shunt group in the shunt.

[0017] 3. The variable resistance alloy shunt is made of copper-aluminum alloy with an oxide film on its surface. The copper-aluminum alloy has both high conductivity and high temperature resistance, and the surface is coated with an anti-oxidation coating to reduce heat loss.

[0018] 4. A smart circuit breaker is connected in series on the shorting wire to realize overload and short circuit protection and on / off control of the shunt branch; each shunt branch is equipped with one smart circuit breaker, which can achieve millisecond-level on / off response. Based on real-time feedback of shunt current data, it has automatic overcurrent and overheat protection functions.

[0019] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will now be described in further detail with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the three-dimensional connection structure of the present invention.

[0021] Figure 2 This is a schematic diagram of the three-dimensional connection structure from another angle of the present invention.

[0022] Figure 3 This is a schematic diagram of the connection structure of the adjustable shunt of the present invention.

[0023] Among them, the roasting tank is 1; the downstream tank is 2; the corresponding position of the column busbar is 3; the shorting wire is 4; the horizontal busbar of the roasting tank is 5; the adjustable distributor is 6; the box is 6-1; the variable resistance alloy distributor is 6-2; the contact point is 6-3; the cooling device is 6-4; the reciprocating pneumatic device is 6-5; and the air compressor is 6-6. Detailed Implementation

[0024] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be understood that the preferred embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0025] like Figures 1-3 As shown, this invention discloses a method for automatic current distribution during the roasting period of an aluminum electrolytic cell. This method uses temperature data from a temperature acquisition element and current feedback signals from a current detection meter. The central control computer, combined with the roasting process algorithm, presets a temperature-current curve model and automatically adjusts the on / off state of each branch circuit to achieve dynamic and precise control of the roasting current. This avoids a waterfall-like drop when the current decreases, ensuring that the roasting cell 1 completes roasting according to the preset temperature curve.

[0026] The relationship between the enhanced current, bath temperature change, and required current for roasting in this roasting process algorithm is as follows: ; in: .

[0027] Example: A 500kA aluminum electrolytic cell uses a coke preheating method for roasting and startup, with a roasting startup cycle of 88 hours. It has 6 vertical busbars, i.e., 6 adjustable current distributors 6. An automatic current distribution method is used. Before power-on, a low-current pre-roasting period of 8 hours is maintained, with most of the current flowing through the adjustable current distributors 6 to the downstream cell 2. Starting from the 8th hour, the current to the roasting cell 1 is gradually increased to raise its temperature. By the 32nd hour, all the current flows through the roasting cell 1, completing the current distribution task. Based on the online monitoring of the cell temperature data, the current flowing through each adjustable current distributor 6 at each hour is calculated as shown in the table below: ; As shown in the table above, during the process of increasing the temperature of calcination tank 1, the current can be smoothly transitioned through dynamic and precise control.

[0028] This system for automatic current distribution during the roasting period of an aluminum electrolytic cell includes a roasting cell 1, a downstream cell 2, a temperature acquisition element, a shorting wire 4, an adjustable shunt 6, a current meter, a relay converter, and a central control computer. Specifically, the downstream cell 2 is located adjacent to the roasting cell 1; the temperature acquisition element is located at position 3 on the corresponding column busbar within the roasting cell 1; the shorting wire 4 is connected between the horizontal busbar 5 of the roasting cell and the column busbar of the downstream cell 2, serving as a shunt branch; the shorting wire 4 is connected to both the horizontal busbar 5 of the roasting cell and the column busbar of the downstream cell 2 via adjustable clamps; the adjustable shunt 6 is connected in series with the shorting wire 4 to linearly adjust the current distribution from the horizontal busbar 5 of the roasting cell to the downstream cell. The magnitude of the current output from tank 2 indirectly controls the current entering roasting tank 1, achieving stable temperature rise in roasting tank 1. A current sensor is integrated into the adjustable shunt 6 to monitor the current parameters of the shunt branches in real time. The current sensor provides real-time feedback of the shunt branch current data to the central control computer, providing baseline data for the central control computer to adjust the adjustable shunt 6. A relay converter converts the analog signal output from the temperature acquisition element into a standard industrial signal. The central control computer collects the temperature signal output from the relay converter and the current data from the current sensor in real time, and controls the adjustable shunt 6 to perform current adjustment operations according to preset control logic. Specifically, the central control computer includes an integrated controller, employing a PLC programmable logic controller with a built-in roasting process control algorithm. The controller receives temperature data from the temperature acquisition element and current feedback signals from the current sensor, and automatically adjusts the on / off state of each shunt branch through a preset temperature-current curve model, achieving dynamic and precise control of the roasting current.

[0029] The integrated controller is connected to the central control computer in the workshop control room via industrial Ethernet, enabling remote visual monitoring of temperature, current, and voltage during the roasting process. The central control computer has the following functions: 1. Real-time display of key parameters such as temperature, branch current, and branch voltage in each column busbar area of ​​the roasting electrolytic cell; 2. Supports custom settings for calcination temperature profiles and current distribution strategies; 3. Automatically record data throughout the roasting process and generate traceable roasting process technology reports; 4. Real-time alarm for abnormal situations and automatic activation of emergency control procedures, such as sudden temperature rise or current over-limit.

[0030] Furthermore, the temperature acquisition element is an armored thermocouple, which is located in the contact area between the anode carbon block and the molten aluminum. Specifically, the analog signal output by the armored thermocouple is transmitted to the relay converter through a high-temperature shielded wire.

[0031] Furthermore, the adjustable shunt 6 includes a housing 6-1, a variable resistance alloy shunt 6-2, a contact point 6-3, a cooling device 6-4, a reciprocating pneumatic device 6-5, and an air compressor 6-6. Specifically, the housing 6-1 is connected in series with the jumper wire 4 to house the various components of the shunt. One end of the variable resistance alloy shunt 6-2 is connected to the jumper wire 4 leading to the downstream tank 2, and its surface is provided with a slidable contact point 6-3, which is connected to the input jumper wire 4 connecting to the horizontal busbar 4. The contact point 6-3 can slide from one end of the variable resistance alloy shunt 6-2 to the other end, changing the resistance value on the shunt branch and thus adjusting the shunt current. The cooling device 6-4 is located inside the housing 6-1 and is used to cool the variable resistance alloy shunt 6-2 in real time to prevent it from being damaged by overheating. Specifically, the cooling device 6-4 includes a built-in fan, such as... Figure 3 As shown, in the initial stage of current shunting, contact point 6-3 is close to end b. When the voltage is constant and the resistance is low, heat will be generated. Q_heat = W = Pt = UIt = (U² / R)t. After reducing the current, mechanical ventilation is no longer needed. Cooling down, by A built-in fan ensures stable operation of the reciprocating pneumatic device 6-5. The reciprocating pneumatic device 6-5 connects to contact point 6-3, driving it to slide back and forth along the variable resistance alloy shunt 6-2. The reciprocating pneumatic device 6-5 is connected to the air compressor 6-6 or the shell-breaking system installed on the electrolytic cell to obtain pneumatic power. The pneumatic power of the air compressor 6-6 or the shell-breaking system is protected from magnetic field interference and the current can be controlled by adjusting the resistance of the shunt group in the adjustable shunt 6.

[0032] Furthermore, the variable resistance alloy shunt 6-2 is made of copper-aluminum alloy with an oxide film on its surface; the copper-aluminum alloy has both high conductivity and high temperature resistance, and the surface is coated with an anti-oxidation coating to reduce heat loss.

[0033] Furthermore, a smart circuit breaker is connected in series on shorting wire 4 to realize overload and short-circuit protection and on / off control of the shunt branch; each shunt branch is equipped with a smart circuit breaker, which can achieve millisecond-level on / off response. Based on real-time feedback of shunt current data, it has automatic overcurrent and overheat protection functions.

[0034] During use, before the electrolytic cell is roasted, the operator connects the input terminal of the adjustable shunt 6 to the horizontal busbar 5 of the roasting cell and secures it with an adjustable clamp at the input terminal of the adjustable shunt 6. The output terminal of the adjustable shunt 6 is connected to the column busbar of the downstream cell 2 and secured with an adjustable clamp at the output terminal of the adjustable shunt 6. Then, the armored thermocouple of the temperature measuring module is inserted into the corresponding position 3 of the column busbar of the roasting cell 1. The technicians preset the roasting temperature curve and the corresponding current distribution strategy in the central control computer according to the type of electrolytic cell (such as 400KA, 500KA, 600KA) and the condition of the lining. In the initial stage of power-on roasting, the system operates at the maximum current shunt rate, guiding the preset current into the downstream tank 2 through the shunt group. As the temperature of the roasting tank 1 gradually increases, the central control computer, based on the data fed back by the temperature measurement module, sequentially cuts off the current shunt branches of each column bus according to the preset strategy, so that the current flowing into the roasting tank 1 is evenly distributed and increases linearly. When the roasting temperature reaches the preset threshold (usually 900-950℃), all shunt branches are automatically disconnected, and the full current is guided into the roasting tank 1, completing the roasting process.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments without departing from the technical solution of the present invention and based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for automatic current distribution during the roasting period of an aluminum electrolytic cell, characterized in that, This method: By combining the temperature data from the temperature acquisition element with the current feedback signal from the current detection meter, the central control computer, in conjunction with the roasting process algorithm, presets the temperature-current curve model and automatically adjusts the on / off state of each branch circuit to achieve dynamic and precise control of the roasting current, thereby avoiding the waterfall-like cliff phenomenon when the current decreases, and ensuring that the roasting tank (1) completes roasting according to the preset temperature curve.

2. The method for automatic current distribution during the roasting period of an aluminum electrolytic cell according to claim 1, characterized in that, The relationship between the enhanced current, bath temperature change, and required current for roasting in this roasting process algorithm is as follows: 。 3. The method for automatic current distribution during the roasting period of an aluminum electrolytic cell according to claim 1, characterized in that, The above: 。 4. A system for automatic current distribution during the roasting period of an aluminum electrolytic cell, characterized in that it include: A roasting tank (1) is provided with a downstream tank (2) adjacent to the roasting tank (1); Temperature acquisition element, the temperature acquisition element is located at the position (3) corresponding to the column busbar inside the roasting tank (1); Shorting wire (4), the shorting wire (4) is connected between the horizontal busbar (5) of the roasting tank and the column busbar of the downstream tank (2) as a branch line; An adjustable current shunt (6) is connected in series with a shorting wire (4) to linearly adjust the current output from the horizontal busbar (5) of the roasting tank to the downstream tank (2), thereby indirectly controlling the current value entering the roasting tank (1) and realizing stable heating of the roasting tank (1). A current sensor, which is integrated inside the adjustable shunt (6), is used to detect the current parameters of the shunt branch in real time. A relay converter, used to convert the analog signal output by the temperature acquisition element into a standard industrial signal; The central control computer collects the temperature signal output by the relay converter and the current data of the current detection meter in real time, and controls the adjustable shunt (6) to perform current regulation operation according to the preset control logic.

5. The system for automatic current distribution during the roasting period of an aluminum electrolytic cell according to claim 4, characterized in that, The temperature acquisition element is an armored thermocouple, which is located in the contact area between the anode carbon block and the molten aluminum.

6. The system for automatic current distribution during the roasting period of an aluminum electrolytic cell according to claim 4, characterized in that, The adjustable shunt (6) includes: The housing (6-1) is connected in series with the jumper wire (4) to accommodate the components of the shunt. A variable resistance alloy shunt (6-2) is provided. One end of the variable resistance alloy shunt (6-2) is connected to a short wire (4) leading to the downstream tank (2). Its surface is provided with a sliding contact point (6-3). The contact point (6-3) is connected to the input short wire (4) connecting the horizontal busbar (4). The contact point (6-3) can slide along one end of the variable resistance alloy shunt (6-2) to the other end. By sliding, the resistance value on the shunt branch is changed, thereby adjusting the shunt current. Cooling device (6-4), which is located inside the box (6-1), is used to cool the variable resistance alloy shunt (6-2) in real time to prevent it from being damaged due to overheating; A reciprocating pneumatic device (6-5) is connected to a contact point (6-3) and is used to drive the contact point (6-3) to slide back and forth along the variable resistance alloy shunt (6-2).

7. The system for automatic current distribution during the roasting period of an aluminum electrolytic cell according to claim 6, characterized in that, The reciprocating pneumatic device (6-5) is connected to the air compressor (6-6) or the shell-breaking system installed on the electrolytic cell to obtain pneumatic power.

8. The system for automatic current distribution during the roasting period of an aluminum electrolytic cell according to claim 6, characterized in that, The variable resistance alloy shunt (6-2) is made of copper-aluminum alloy and has an oxide film on its surface.

9. The system for automatic current distribution during the roasting period of an aluminum electrolytic cell according to claim 1, characterized in that: A smart circuit breaker is connected in series on the shorting wire (4) to realize overload and short circuit protection and on / off control of the branch circuit.

10. The system for automatic current distribution during the roasting period of an aluminum electrolytic cell according to any one of claims 4-9, characterized in that: The shorting wire (4) is connected to the horizontal busbar (5) of the roasting tank and the column busbar of the downstream tank (2) respectively through adjustable clamps.

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