Method for uniformly discharging electricity from two sides of cathode of aluminum electrolysis cell

Abstract

The invention discloses a method for uniformly discharging electricity from two sides of a cathode of an aluminum electrolysis cell, relates to the technical field of aluminum electrolysis cells, and mainly aims to solve the problem of non-uniform electricity discharging from two sides of the cathode of the aluminum electrolysis cell in the prior art. According to the main technical scheme, the method for uniformly discharging electricity from the two sides of the cathode of the aluminum electrolysis cell comprises the following steps of: (1) connecting one end of a balanced connection bus to a cathode bus at the end part of an electricity inlet side, and connecting the other end of the balanced connection bus to a short-circuit temporary bus; wherein the short-circuit temporary bus penetrates through the middle tank bottom of the aluminum electrolysis tank, and the short-circuit temporary bus is used for being connected with a stand column bus of a downstream tank when a standard tank stops and is short-circuited; and (2) after the connection of the power inlet side cathode bus, the balanced connection bus and the short-circuit temporary bus is completed, monitoring the current of each branch of the power inlet side cathode and the power outlet side cathode, and adjusting the sectional area, the length or the connection part of the balanced connection bus according to the monitoring result.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum electrolysis cells, and in particular to a method for uniformly discharging electricity on both sides of a cathode of an aluminum electrolysis cell. Background Art

[0002] Currently, the mainstream electrolytic cell types in my country are 400KA-600KA, and their busbar systems are designed for 5-7 power input points across a large surface. However, as the length of the electrolytic cell increases, the busbar system design faces greater challenges. The problem of uneven power distribution on both sides of the cathode, namely the power input side and the power output side (or A and B sides), is particularly prominent.

[0003] In the existing busbar system design, during normal operation of the electrolytic cell, DC power is distributed from one side of the cell's long axis (the power inlet side, or side A) to the anode busbar, which is then fed through 5-7 columns. After passing through the anode, electrolyte, molten aluminum, and cathode, the current exits the cell from the side through the cathode steel rods, where it is fed by multiple branches and converged into multiple sets of cathode busbars. These cathode busbars are then grouped together on the other side of the long axis (the power outlet side, or side B) to feed the column busbars of the next electrolytic cell. However, due to the long length of the electrolytic cells, the busbar design takes this difference into account, with cross-connections implemented to ensure a relatively balanced voltage across the cathode branches (even during the short-circuit state of the cell). When the cell is idle, the two columns at the ends typically cross over via a short-circuit line to the next cell. However, since the corresponding cathode branches of the 1 to 3 columns are closer together, temporary busbars are required to assist in carrying the current during a short-circuit state, ensuring that the currents in the columns of the downstream cells are roughly balanced as in normal operation.

[0004] However, many existing busbar designs for the power inlet and outlet sides lack proper electrical balance, and the impact of actual busbar temperatures on production is not fully considered during design. Large-surface, multi-point (5-7-point) power inlet electrolytic cells inherently exhibit a large magnetic field along the long axis X, causing the molten aluminum to surge from the power inlet side (side A) to the power outlet side (side B) under electromagnetic force. These factors can lead to imperfect formation of the furnace rib in the middle of side B, resulting in excessively high cathode current and high steel bar temperatures on side B. This can severely impact the cathode current ratio between the power inlet and power outlet sides (sides A and B), which is 40-45:55-60. This disrupts the symmetry of the furnace bottom and rib on the power inlet and power outlet sides, significantly impacting production. Summary of the Invention

[0005] In view of this, the present invention provides a method for uniformly distributing electricity on both sides of the cathode of an aluminum electrolysis cell, the main purpose of which is to solve the problem of uneven electricity distribution on both sides of the cathode of an aluminum electrolysis cell in the prior art.

[0006] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0007] The present invention provides a method for uniformly discharging electricity on both sides of the cathode of an aluminum electrolysis cell, the method comprising the following steps:

[0008] (1) Connect one end of the balancing busbar to the cathode busbar at the incoming power side, and the other end to the short-circuit temporary busbar;

[0009] The temporary short-circuit busbar runs through the middle bottom of the aluminum electrolytic cell and is used to connect the column busbar of the downstream cell when the cell is stopped and short-circuited.

[0010] (2) After completing the connection of the cathode busbar on the power input side, the balancing connection busbar and the short-circuit temporary busbar, monitor the current of each cathode branch on the power input and output sides, and adjust the cross-sectional area, length or connection position of the balancing connection busbar according to the monitoring results.

[0011] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0012] Optionally, before installing the balanced connection bus, the following calculations need to be performed:

[0013] (1) Calculate the voltage drop V2 of the balanced connection bus:

[0014] V2=V0-V1, V0 is the voltage drop of the cathode busbar of the electrolytic cell, and V1 is the voltage drop of the short-circuit temporary busbar;

[0015] (2) Calculate the cross-sectional area of the balanced connection busbar:

[0016] S = K × I × r0 × (1 + α △ T) × L / V2, where: K is the safety factor (1.0-1.2), I is the current to be balanced, r0 is the resistivity of aluminum at room temperature, α is the resistance temperature coefficient of aluminum, ΔT temperature difference is the difference between the balancing busbar temperature and room temperature, and L is the on-site installation length of the balancing busbar.

[0017] Optionally, the balancing connecting busbar is made of aluminum busbar or aluminum soft strip.

[0018] Optionally, two ends of the balancing connection bus are respectively welded to the incoming side cathode bus and the short-circuit temporary bus.

[0019] Optionally, two ends of the balancing connection bus are respectively crimped to the incoming side cathode bus and the short-circuit temporary bus.

[0020] Optionally, the current density of the balanced connecting busbar is 0.4-1.0A / mm 2 .

[0021] By means of the above technical solution, the present invention has at least the following advantages:

[0022] 1. Busbar design optimization:

[0023] Between the power input side (side A) and the power output side (side B) of the electrolytic cell, a busbar or soft belt with a certain cross-section is added to connect the branch with less current on side A and the temporary busbar.

[0024] The cross-section of the busbar or flexible belt is selected based on the amount of current that needs to be balanced, ensuring that the cathode power output ratio on the input and output sides is basically maintained at around 50:50.

[0025] 2. Utilization of temporary busbar:

[0026] When the electrolytic cell is in the stopped state (short-circuited state), a temporary busbar is used to bear part of the current, and the current is guided from the branch with less current on the A side to the temporary busbar through the additional busbar or soft belt, and then enters the next electrolytic cell.

[0027] In this way, the current on both sides of AB is adjusted to be basically uniform, avoiding the problem of serious uneven current output on both sides of the cathode.

[0028] 3. Temperature compensation design:

[0029] In busbar design, the influence of each busbar temperature is taken into consideration, and the busbar cross-section and layout are reasonably designed to ensure the electrical balance of the busbar system in a high temperature environment.

[0030] In summary, by optimizing the busbar design and using temporary busbars to bear part of the current, the problem of uneven power output on both sides of the cathode of large aluminum electrolytic cells was effectively solved, ensuring that the power output ratio on both sides of the cathode of the electrolytic cell is basically maintained at around 50:50, thereby improving the operating efficiency and stability of the electrolytic cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the positional relationship of a series of aluminum electrolytic cells;

[0032] Figure 2 A schematic diagram of the installation of a balanced connection busbar for a seven-column electrolytic cell provided by an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of the installation of a balanced connection busbar for a six-column electrolytic cell provided by an embodiment of the present invention;

[0034] Figure 4 A schematic diagram of the installation of a balanced connecting busbar for a five-column electrolytic cell provided in an embodiment of the present invention.

[0035] The reference numerals in the drawings of the specification include:

[0036] Seven-column electrolytic cell:

[0037] cathode busbars (102, 103, 104, 105) at the end of the power supply side, a balancing connection busbar (101), and a short-circuit temporary busbar (106, 107, 108);

[0038] Six-column electrolytic cell:

[0039] cathode busbars (202, 203, 204, 205) at the end of the power supply side, a balancing connection busbar (201), and a short-circuit temporary busbar (206, 207);

[0040] Five-column electrolytic cell:

[0041] Cathode busbars (302, 303, 304, 305) at the power-input side end, a balancing connection busbar (301), and a short-circuit temporary busbar (306). DETAILED DESCRIPTION

[0042] To further illustrate the technical means and effects employed by the present invention to achieve its intended objectives, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention is provided in conjunction with the accompanying drawings and preferred embodiments. In the following description, different references to "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0043] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0044] One embodiment of the present invention provides a method for uniformly discharging electricity on both sides of the cathode of an aluminum electrolysis cell, comprising the following steps:

[0045] Step 1: Before installing the balanced connection bus, the following calculations must be performed:

[0046] (1) Calculate the voltage drop V2 of the balanced connection bus:

[0047] V2=V0-V1, V0 is the voltage drop of the cathode busbar of the electrolytic cell, and V1 is the voltage drop of the short-circuit temporary busbar;

[0048] (2) Calculate the cross-sectional area of the balanced connection busbar:

[0049] S = K × I × r0 × (1 + αΔT) × L / V2, where: K is the safety factor (1.0-1.2), I is the current to be balanced, r0 is the resistivity of aluminum at room temperature, α is the temperature coefficient of resistance of aluminum, ΔT is the difference between the temperature of the balancing busbar and room temperature, and L is the on-site installation length of the balancing busbar;

[0050] Specifically, the derivation process of the above calculation formula is as follows:

[0051] R=ρL / S

[0052] R=K×rO×(1+α△T)×L / S

[0053] V2 / I=K×rO×(1+α△T)×L / S

[0054] S=K×I×r0×(1+α△T)×L / V2

[0055] Step 2: Connect one end of the balancing busbar to the cathode busbar at the power-input side, and the other end to the short-circuit temporary busbar;

[0056] The temporary short-circuit busbar runs through the middle bottom of the aluminum electrolytic cell. When the local cell is stopped and short-circuited, the temporary short-circuit busbar is used to connect the column busbar of the downstream cell (one end of the temporary short-circuit busbar is connected to the middle column short-circuit block of the local cell, and the other end is connected to the column busbar of the downstream cell);

[0057] like Figure 1 As shown, specifically, in a series, the aluminum electrolysis cells are connected in series, and the three adjacent aluminum electrolysis cells are the upstream cell, the home cell and the downstream cell in sequence;

[0058] Step 3: After completing the connection of the cathode busbar at the end of the power input side, the balancing connection busbar and the short-circuit temporary busbar, monitor the current of each cathode branch on the power input and output sides, and adjust the cross-sectional area, length or connection position of the balancing connection busbar according to the monitoring results.

[0059] In a specific embodiment, the balancing connecting busbar is made of aluminum busbar or aluminum soft strip.

[0060] In a specific embodiment, both ends of the balancing connection busbar are respectively welded to the cathode busbar at the power-input side end and the short-circuit temporary busbar.

[0061] In a specific embodiment, both ends of the balancing connection bus are respectively crimped to the cathode bus at the power-input side end and the short-circuit temporary bus.

[0062] In a specific embodiment, the current density of the balanced connecting busbar is 0.4-1.0A / mm 2 .

[0063] Example 1

[0064] like Figure 2 As shown, the cathode busbars (102, 103, 104, 105) at the end of the power supply side are connected to the short-circuit temporary busbars (106, 107, 108) through the balancing connection busbar (101).

[0065] Specifically, the cathode busbar node of a 500KA electrolytic cell is as follows: Figure 2 The large seven-point (seven-column) electrolytic cell has an operating current of 500,000A;

[0066] When the balancing busbar is not installed, the power output ratio is: incoming side (side A): outgoing side (side B) = 45:55. The cathode output current of the incoming side (side A) is 201000A, so the busbar needs to bear 24000A of current. The cathode output current of the incoming side (side A) can be improved to 225000A. The design adopts 6 balancing busbars, each balancing busbar bears 4000A, with a load of 0.5A / mm 2 Each balanced connecting busbar is 8000mm 2 , a 1*40*200 soft belt bundle was selected (that is, each balancing connection busbar uses 40 soft belts, the cross-sectional thickness of each soft belt is 1mm, and the width is 200mm). After the busbars are connected, the cathode current on both sides is tested, and the power output ratio of the power input side (side A): the power output side (side B) is 49.7:50.3.

[0067] Example 2

[0068] like Figure 3 As shown, the cathode busbars (202, 203, 204, 205) at the end of the power supply side are connected to the short-circuit temporary busbars (206, 207) through the balancing connection busbar (201).

[0069] Specifically, the cathode busbar node of a 420KA electrolytic cell is as follows: Figure 3 The electrolytic cell is a six-point (six-column) power-in electrolytic cell, and the operating current of the electrolytic cell is 420,000A;

[0070] When the balancing busbar is not installed, the cathode current output ratio is: input side (A side): output side (B side) = 46:54, the input side (A side) current is 193200A, and the busbar is designed to bear 16800A current, which can improve the cathode output current of the input side (A side) to an average level of about 210000A. The design adopts 4 balancing busbars, each balancing busbar bears 4200A, with a load of 0.7A / mm 2 Each balanced connecting busbar is 6000mm 2 , a 1*30*200 soft belt bundle was selected (that is, each balanced connecting busbar uses 30 soft belts, the cross-sectional thickness of each soft belt is 1mm, and the width is 200mm). After connecting using the above method, the power output ratio on both sides of the cathode of the electrolytic cell was basically 48.5:51.5 after testing.

[0071] Example 3

[0072] like Figure 4 As shown, the cathode busbars (302, 303, 304, 305) at the end of the power-input side are connected to the short-circuit temporary busbar (306) through the balancing connection busbar (301).

[0073] Specifically, the cathode busbar node of a 300KA electrolytic cell is as follows: Figure 4 The electrolytic cell is a five-point (five-column) power-in electrolytic cell, and the operating current of the electrolytic cell is 300,000A;

[0074] When no balancing busbar is installed, the cathode power output ratio is: incoming side (A side): outgoing side (B side) = 44:56. The incoming side (A side) current is 132000A. The busbar is designed to bear 18000A of current. The incoming side cathode (A side) power output current can be improved to 150000A. Four balancing busbars are used, each balancing busbar bears 4500A, and the current density is 0.8A / mm 2 The cross-sectional area of each balanced connecting busbar is 5625mm 2 , a 1*31*200 soft belt bundle was selected (that is, each balancing connection busbar uses 31 soft belts, the cross-sectional thickness of each soft belt is 1mm, and the width is 200mm). After connecting using the above method, the cathode current on both sides was tested, and the power output ratio on both sides of the electrolytic cell cathode basically tended to 49.5:50.5.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for uniformly discharging electricity on both sides of the cathode of an aluminum electrolysis cell, characterized in that: The steps include: (1) Connect one end of the balancing busbar to the cathode busbar at the incoming power side, and the other end to the short-circuit temporary busbar; The temporary short-circuit busbar runs through the middle bottom of the aluminum electrolytic cell and is used to connect the column busbar of the downstream cell when the cell is stopped and short-circuited. (2) After completing the connection of the cathode busbar at the end of the power input side, the equalizing connection busbar and the short-circuit temporary busbar, monitor the current of each cathode branch on the power input and output sides, and adjust the cross-sectional area, length or connection position of the equalizing connection busbar according to the monitoring results.

2. The method for uniformly discharging electricity on both sides of the cathode of an aluminum electrolysis cell according to claim 1, characterized in that: Before installing the balanced connection busbar, the following calculations must be made: (1) Calculate the voltage drop V2 of the balanced connection bus: V2=V0-V1, V0 is the voltage drop of the cathode busbar of the electrolytic cell, and V1 is the voltage drop of the short-circuit temporary busbar; (2) Calculate the cross-sectional area of the balanced connection busbar: S = K × I × r0 × (1 + α △ T) × L / V2, where: K is the safety factor (1.0-1.2), I is the current to be balanced, r0 is the resistivity of aluminum at room temperature, α is the resistance temperature coefficient of aluminum, ΔT temperature difference is the difference between the balancing busbar temperature and room temperature, and L is the on-site installation length of the balancing busbar.

3. The method for uniformly discharging electricity on both sides of the cathode of an aluminum electrolysis cell according to claim 1, characterized in that: The balanced connecting busbar is made of aluminum busbar or aluminum soft strip.

4. The method for uniformly discharging electricity on both sides of the cathode of an aluminum electrolysis cell according to claim 1, characterized in that: The two ends of the balancing connection bus are respectively welded to the cathode bus at the power-input side end and the short-circuit temporary bus.

5. The method for uniformly discharging electricity on both sides of the cathode of an aluminum electrolysis cell according to claim 1, characterized in that: The two ends of the balancing connection bus are respectively crimped to the cathode bus at the power-input side end and the short-circuit temporary bus.

6. The method for uniformly discharging electricity on both sides of the cathode of an aluminum electrolysis cell according to claim 1, characterized in that: The current density of the balanced connecting busbar is 0.4-1.0A / mm 2 .

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