Method for determining the current efficiency of an aluminium electrolysis
By detecting the nitrogen gas integral and carbon dioxide volume fraction of the anode gas in the aluminum electrolytic cell, and combining the formula η=50+(%CO2)/2+m, the problem of low current efficiency measurement results in the partially heated electrolytic cell was solved, and high-precision current efficiency measurement was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHENGZHOU NON FERROUS METALS RES INST CO LTD OF CHALCO
- Filing Date
- 2023-02-09
- Publication Date
- 2026-06-02
Smart Images
Figure CN116223592B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of aluminum electrolysis technology, and more specifically, to a method for measuring the current efficiency of aluminum electrolysis. Background Technology
[0002] The current efficiency of aluminum electrolysis is a crucial economic and technical indicator in aluminum electrolysis production, serving as a vital basis for enterprises to adjust process parameters. A common method for measuring the current efficiency of aluminum electrolytic cells is the anode gas analysis method. This method is based on the relationship between CO2 concentration in the anode gas and current efficiency. By collecting gas emitted during electrolysis and analyzing its concentration, the current efficiency at a specific moment can be obtained. The test results quickly reflect changes in the current efficiency of the electrolytic cell over a certain period, providing a comprehensive understanding of the cell's operating status. When the electrolytic cell's condition is manually adjusted, it allows for accurate and rapid understanding of changes in the cell's state, providing reliable data for process improvement and even management. It also provides guidance for daily process operations and strong technical support for optimizing the electrolytic cell's industrial and operational procedures. However, during on-site testing, results are affected by factors such as the flame and process conditions, especially for overheated electrolytic cells, where test results tend to be significantly lower. Analysis revealed that when the electrolytic cell is overheated, the cavity under the shell is larger and the opening of the flame hole is larger. When the aluminum liquid in the electrolytic cell fluctuates, air in the electrolytic cell can easily flow under the shell and even react with carbon in the electrolytic cell, affecting the volume fraction of the gas and resulting in low current efficiency.
[0003] Therefore, those skilled in the art urgently need a method for measuring the current efficiency of aluminum electrolysis that can accurately measure the current efficiency of aluminum electrolysis. Summary of the Invention
[0004] The embodiments of this application provide a method for measuring the current efficiency of aluminum electrolysis, which can accurately measure the current efficiency of aluminum electrolysis.
[0005] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.
[0006] According to one aspect of the embodiments of this application, a method for determining the current efficiency of aluminum electrolysis is provided. The method includes: detecting the nitrogen gas integral number and carbon dioxide volume fraction in an anode gas collected from an aluminum electrolysis cell; determining the validity of the anode gas detection result based on the nitrogen gas integral number; and if the anode gas detection result is valid, determining the aluminum electrolysis current efficiency based on the carbon dioxide volume fraction.
[0007] In some embodiments of this application, the detection of the nitrogen gas integral number and carbon dioxide volume fraction in the anode gas collected from the aluminum electrolytic cell includes: within a second set time period, at a second set frequency, detecting the average value of the nitrogen gas integral number and carbon dioxide volume fraction in the anode gas collected from the aluminum electrolytic cell within a third set time period, wherein the third set time period is shorter than the second set time period.
[0008] In some embodiments of this application, determining the validity of the anolyte gas detection result based on the nitrogen gas integral number includes: if the nitrogen gas integral number is not greater than 0.1%, the anolyte gas detection result is determined to be valid; if the nitrogen gas integral number is greater than 0.1%, the anolyte gas detection result is determined to be invalid.
[0009] In some embodiments of this application, determining the aluminum electrolysis current efficiency based on the carbon dioxide volume fraction includes: calculating the aluminum electrolysis current efficiency according to the following formula:
[0010] η = 50 + (%CO2) / 2 + m
[0011] Where η is the aluminum electrolysis current efficiency, m is the correction coefficient, and %CO2 is the volume fraction of carbon dioxide.
[0012] In some embodiments of this application, the method further includes collecting the anode gas from the aluminum electrolytic cell before detecting the nitrogen gas integral in the anode gas collected from the aluminum electrolytic cell.
[0013] In some embodiments of this application, based on the aforementioned scheme, the collection of anode gas in the aluminum electrolytic cell includes: collecting anode gas in the aluminum electrolytic cell at a first set frequency within a first set time period.
[0014] In some embodiments of this application, based on the aforementioned scheme, the step of collecting the anode gas in the aluminum electrolysis cell at a first set frequency includes: collecting the anode gas in the aluminum electrolysis cell through a flue gas sampler at a first set frequency.
[0015] In some embodiments of this application, based on the aforementioned scheme, before collecting the anode gas in the aluminum electrolysis cell using a flue gas sampler at a first set frequency, the method further includes: setting a flue gas sampler in the aluminum electrolysis cell.
[0016] In some embodiments of this application, based on the aforementioned scheme, the step of setting a flue gas sampler in an aluminum electrolysis cell includes: setting a collection hole on the electrolyte crust surface of the aluminum electrolysis cell, and setting the collection port of the flue gas sampler above the center of the collection hole, 20mm to 50mm away from the electrolyte liquid surface.
[0017] In some embodiments of this application, the method further includes: if the anode gas detection result is invalid, checking the pipeline sealing of the aluminum electrolysis cell and the rationality of the gas sampling location. Based on the above scheme, this application has at least the following advantages or advancements:
[0018] In some embodiments of this application, the technical solutions provide the following: the nitrogen gas integral and carbon dioxide volume fraction in the anolyte gas collected from the aluminum electrolysis cell can be detected; the validity of the anolyte gas detection result is determined based on the nitrogen gas integral; if the anolyte gas detection result is valid, the aluminum electrolysis current efficiency is determined based on the carbon dioxide volume fraction. The method for determining the aluminum electrolysis current efficiency provided in this application is reasonable and can avoid the problem of existing methods where the measurement results are significantly lower due to the influence of factors such as the flame, process, and air flowing into the electrolysis cell and reacting below the shell surface.
[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description
[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.
[0021] Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.
[0022] In the attached diagram:
[0023] Figure 1 A simplified flowchart of a method for measuring the current efficiency of aluminum electrolysis according to one embodiment of this application is shown. Detailed Implementation
[0024] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.
[0025] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.
[0026] It should be noted that "multiple" in this article refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0027] Please see Figure 1 .
[0028] Figure 1 A simplified flowchart of a method for determining the current efficiency of aluminum electrolysis according to one embodiment of this application is shown, as follows: Figure 1 As shown, the method may include steps S101-S102:
[0029] Step S101: Detect the nitrogen gas integral number and carbon dioxide volume fraction in the anode gas collected from the aluminum electrolysis cell, and determine the validity of the anode gas detection results based on the nitrogen gas integral number.
[0030] Step S102: If the anode gas detection result is valid, then determine the aluminum electrolysis current efficiency based on the carbon dioxide volume fraction.
[0031] In this application, the nitrogen gas integral and carbon dioxide volume fraction in the anolyte gas collected from the aluminum electrolysis cell can be detected. The validity of the anolyte gas detection result is determined based on the nitrogen gas integral. If the anolyte gas detection result is valid, the aluminum electrolysis current efficiency is determined based on the carbon dioxide volume fraction. The aluminum electrolysis current efficiency determination method provided in this application is reasonable and can avoid the problem of existing methods having significantly lower measurement results due to the influence of factors such as flame conditions, process conditions, and air flowing into the electrolysis cell and reacting below the shell surface.
[0032] Prior to step S101, the method may further include collecting anolyte gas from the aluminum electrolytic cell.
[0033] In this application, a flue gas sampler can be first installed on the aluminum electrolysis cell: a collection hole is set on the electrolyte crust surface of the aluminum electrolysis cell, and the collection port of the flue gas sampler is set above the center of the collection hole, 20mm to 50mm away from the electrolyte liquid surface.
[0034] Specifically, after determining the electrolytic cell to be measured, a circular hole can be drilled on the electrolyte crust surface, with the hole size roughly the same as the sampling port of the flue gas sampler. The sampling port of the flue gas sampler is placed above the center of the sampling hole, 20mm to 50mm from the electrolyte surface. The sampling hole of the flue gas sampler is surrounded by anolyte gas. By keeping the sampling port of the flue gas sampler stable, the anolyte gas is obtained; the sampled gas is the collected anolyte gas.
[0035] Next, within the first set time period, at the first set frequency, the anode gas in the aluminum electrolysis cell can be collected by a flue gas sampler.
[0036] In this application, gas is collected at the collection holes of the aluminum electrolytic cell at a first set time period according to a first set frequency to obtain the corresponding anode gas, wherein the number of times gas is collected at each collection hole is greater than or equal to 3.
[0037] For example, the gas volume fraction can be determined intermittently. Each electrolytic cell undergoes current efficiency testing for at least three consecutive days (the first set time period is three days). Testing is conducted twice daily (the first set frequency is twice per day), with an interval of at least four hours between adjacent tests. Each test uses at least two sampling points (two or more sampling holes per test, the number of which can be adjusted based on the specific number of sampling holes). Each sampling hole collects gas at least three times. The electrolytic cell current efficiency can be taken as the average of all aluminum electrolysis current efficiencies obtained over the three days.
[0038] In this application, the gas volume fraction of each gas component can be measured by sampling first and then testing, which is used to calculate the aluminum electrolysis current efficiency. This achieves an intermittent detection mode, and the average of all calculated values can yield a more accurate aluminum electrolysis current efficiency.
[0039] In this application, the method for detecting the nitrogen gas integral number and carbon dioxide volume fraction in the anode gas collected from the aluminum electrolytic cell may include: within a second set time period, at a second set frequency, detecting the average value of the nitrogen gas integral number and carbon dioxide volume fraction in the anode gas collected from the aluminum electrolytic cell within a third set time period, wherein the third set time period is shorter than the second set time period.
[0040] In this application, within a second predetermined time period, at a second predetermined frequency, the average gas volume fractions of CO2 and N2 are measured at the detection port of the aluminum electrolysis cell during a third predetermined time period. The third predetermined time period is shorter than the second predetermined time period, and each detection port is measured at least three times. It should be noted that the detection port mentioned in this application embodiment can be the collection hole mentioned in the above embodiments, or the detection port may be larger than the collection hole, mainly depending on the size of the detection equipment. This application embodiment does not impose specific limitations.
[0041] For example, the gas volume fraction can be measured continuously, with each measurement lasting at least 10 minutes (the third set time period is 10 minutes). Real-time measuring equipment is used, and each electrolytic cell undergoes current efficiency testing for at least 3 consecutive days (the second set time period is 3 days), with two tests per day (the second set frequency is 2 times / day), and an interval of at least 4 hours between tests. Each test has at least two sampling points, and each sampling point takes at least 3 gas samples. Alternatively, without gas sampling, the measuring equipment can be directly placed at the detection port for measurement. Each test can last 10 minutes, and the average value within that 10-minute period is used as the output value for that test. The average current efficiency is obtained by averaging the output values from all tests over 3 days.
[0042] In this application, determining the validity of the anolyte gas detection result based on the nitrogen gas integral number includes: if the nitrogen gas integral number is not greater than 0.1%, the anolyte gas detection result is determined to be valid; if the nitrogen gas integral number is greater than 0.1%, the anolyte gas detection result is determined to be invalid.
[0043] In this application, the method for determining the aluminum electrolysis current efficiency based on the carbon dioxide volume fraction may include: calculating the aluminum electrolysis current efficiency according to the following formula:
[0044] η = 50 + (%CO2) / 2 + m
[0045] Where η is the aluminum electrolysis current efficiency, m is the correction coefficient, and %CO2 is the volume fraction of carbon dioxide. It should be noted that each parameter in the above formula can be used in the calculation as a percentage, and this application embodiment does not impose specific limitations. The correction coefficient m can be set according to the performance, process characteristics, and environmental characteristics of the specific aluminum electrolysis equipment, and this application embodiment does not impose specific limitations.
[0046] In this application, the method may further include: if the anode gas detection result is invalid, checking the pipeline sealing of the aluminum electrolysis cell and the rationality of the gas sampling location.
[0047] In this application, the volume fraction of N2 in the anode gas collected from the aluminum electrolysis cell is detected. When the volume fraction of N2 is not greater than 0.1%, the detection result is valid; otherwise, the equipment pipeline is checked for leaks, the location of the gas sampling pipe is reasonable, and the location of the gas sampling hole is reasonable.
[0048] To enable those skilled in the art to gain a deeper understanding of this application, the following description will be provided in conjunction with specific embodiments.
[0049] Example 1
[0050] Prior to this test, the %N2 volume fraction was 0.3%, and after treatment, the %N2 volume fraction was 0%. The gas volume fraction was determined continuously.
[0051]
[0052]
[0053] Example 2
[0054] Prior to this test, the %N2 volume fraction was 0.4%, and after treatment, the %N2 volume fraction was 0%. The gas volume fraction was determined intermittently.
[0055]
[0056] Example 3
[0057] Prior to this test, the %N2 volume fraction was 0.2%, and after treatment, the %N2 volume fraction was 0%. The gas volume fraction was determined continuously.
[0058]
[0059]
[0060] Example 4
[0061] Prior to this test, the %N2 volume fraction was 1.0%, and after treatment, the %N2 volume fraction was 0%. The gas volume fraction was determined intermittently.
[0062]
[0063] Example 5
[0064] Prior to this test, the %N2 volume fraction was 0.5%, and after treatment, the %N2 volume fraction was 0%. The gas volume fraction was determined continuously.
[0065]
[0066] In actual production, the test electrolytic cell was overheated, the cavity under the shell was large, the flame opening was large, the aluminum liquid in the electrolytic cell fluctuated greatly, and air in the electrolytic cell flowed into the area under the shell, affecting the volume fraction of the gas and resulting in low current efficiency.
[0067] In contrast, this application provides a highly accurate method for measuring the current efficiency of aluminum electrolysis, avoiding the problem that existing methods are affected by factors such as the flame, process, and air flowing into the electrolytic cell and reacting below the shell, resulting in significantly lower test results.
[0068] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.
[0069] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.
Claims
1. A method for determining the current efficiency of aluminum electrolysis, characterized in that, The method includes: The nitrogen gas integral number and carbon dioxide volume fraction in the anode gas collected from the aluminum electrolysis cell are detected, and the validity of the anode gas detection results is determined based on the nitrogen gas integral number. If the anode gas detection result is valid, the aluminum electrolysis current efficiency is determined based on the carbon dioxide volume fraction. The determination of the validity of the anolyte gas detection result based on the nitrogen gas integral number includes: If the nitrogen gas integral is not greater than 0.1%, the anolyte gas detection result is deemed valid. If the nitrogen gas integral is greater than 0.1%, the anolyte gas detection result is deemed invalid. The determination of aluminum electrolysis current efficiency based on the carbon dioxide volume fraction includes: Calculate the current efficiency of aluminum electrolysis using the following formula: η = 50 + (%CO2) / 2 + m Where η is the aluminum electrolysis current efficiency, m is the correction coefficient, and %CO2 is the volume fraction of carbon dioxide.
2. The method according to claim 1, characterized in that, The detection of the nitrogen gas integral and carbon dioxide volume fraction in the anode gas collected from the aluminum electrolysis cell includes: Within a second set time period, at a second set frequency, the average values of the nitrogen gas fraction and carbon dioxide volume fraction in the anode gas collected from the aluminum electrolysis cell are detected within a third set time period, wherein the third set time period is shorter than the second set time period.
3. The method according to claim 1, characterized in that, Before detecting the nitrogen gas fraction in the anode gas collected from the aluminum electrolytic cell, the method further includes: Collect the anode gas inside the aluminum electrolysis cell.
4. The method according to claim 3, characterized in that, The collection of anode gas within the aluminum electrolysis cell includes: Within a first set time period, the anode gas in the aluminum electrolysis cell is collected at a first set frequency.
5. The method according to claim 4, characterized in that, The step of collecting the anode gas in the aluminum electrolysis cell at a first set frequency includes: At the first set frequency, the anode gas in the aluminum electrolysis cell is collected by a flue gas sampler.
6. The method according to claim 5, characterized in that, Before collecting the anode gas in the aluminum electrolysis cell using a flue gas sampler at a first predetermined frequency, the method further includes: A flue gas sampler is installed in the aluminum electrolysis cell.
7. The method according to claim 6, characterized in that, The step of installing a flue gas sampler in the aluminum electrolysis cell includes: A collection hole is set on the electrolyte crust surface of the aluminum electrolysis cell, and the collection port of the flue gas sampler is set above the center of the collection hole, 20mm to 50mm away from the electrolyte liquid surface.
8. The method according to claim 1, characterized in that, The method further includes: If the anode gas detection result is invalid, check the pipeline sealing of the aluminum electrolysis cell and the rationality of the gas sampling location.