Method and system for detecting damage in electrochemical cells using inert gas injection and dynamic differential pressure analysis

Abstract

Damage detection methods for electrolyzers, including: Classifying the cells of the electrolytic cell into categories with damaged membranes; conducting one or more first tests to determine whether the section includes at least one cell, wherein the first tests are based on injecting an inert gas into the anode and cathode of each cell; when the results of the first test confirm that the section contains the at least one cell, replacing the cell and performing a second test to determine whether at least one additional damaged cell remains; when the results of the second test indicate that the at least one additional damaged cell remains, shutting down the electrolytic cell and repeating the execution of the first test, the replacement of the cell, and the execution of the second test; and When the results of the second test indicate that no further damaged cells remain, starting the electrolyzer.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Patent Application No. 63 / 431,857, filed December 12, 2022, the entire contents of which are incorporated herein by reference.

[0002] (Technical field) The present disclosure relates generally to industrial electrolyzers, and more particularly to identifying damaged electrolytic cell membranes before a complete operating cycle begins. [Background technology]

[0003] An electrochemical cell (also referred to herein as a "cell") is a device that performs a chemical decomposition reaction by applying an electric current. Such devices have been used to decompose salt (NaCl) into caustic soda (NaOH) and chlorine (Cl2). They have also been used to decompose potassium chloride into potassium hydroxide and chlorine. Similar processes, such as water electrolysis used to produce hydrogen, have also been performed using electrochemical cells.

[0004] In industrial setups, several cells are combined in series or parallel to carry out reactions. This combination is called an electrolyzer. Most industrial electrochemical cells consist of two electrodes (anode and cathode) and a membrane. In some circumstances, the membrane can also be called a separator, cell separator, cell membrane, exchange membrane, or ion exchange membrane. When cations are exchanged across the membrane, the membrane is called a cation exchange membrane. The oxidation reaction occurs at the anode, and the reduction reaction occurs at the cathode. Modern electrochemical cells use membranes, such as ion exchange membranes, to transfer only the desired ions from one side of the reaction (anode) to the other side (cathode). The efficiency and safety of an industrial electrochemical cell's operation are primarily related to the safety and efficiency of its components. More specifically, the efficiency and safety of an industrial electrochemical cell's operation are related to the safety and efficiency of the cation exchange membrane. Despite their efficiency and environmentally friendly characteristics, cation exchange membranes are susceptible to contaminants exceeding acceptable inlet concentrations and to mechanical defects during installation or operation. The separation efficiency of cation exchange membranes is severely affected by the development of small holes or tears (also called pinholes or pores). Some reasons for the presence of pinholes in cell membranes include the formation of voids, blisters, and delaminations in the membrane due to mechanical stress during maintenance and by contaminated electrolyte, primarily during shutdown and startup operating modes. The presence of pinholes in the membrane can affect cell efficiency in various ways, depending on, for example, the size and location of one or more pinholes (e.g., in a portion of the cell where liquid is present or in another portion of the cell where only gas is present) and the cell's lifetime. Pinholes can reduce the membrane's separation ability to prevent backmigration of hydroxyl ions to the anolyte compartment. Typically, in the case of chlor-alkali electrolysis processes, pinholes cannot be detected during normal operation unless corrosion occurs in the anode coating due to caustic attack. However, the effect of pinholes is noticeable during start-up or shutdown because the pinholes affect the voltage of the cell.Failure of the separation efficiency of one or more ion exchange membranes can result in the mixing of potentially explosive gases such as H2 and Cl2 or H2 and O2, or the leakage of electrolytes that are deadly to humans and harmful to the environment.

[0005] It is widely known to detect damaged membranes by analyzing the current-voltage curves not only at the start-up of the electrolyzer but also after shutdown. However, starting gas production already creates a risk of mixing, which could lead to an explosion, if there is a damaged membrane. Currently, there is no known method to ensure that an explosive mixture of gases from the anode and cathode sides does not form when the electrolyzer is energized. Known membrane leakage tests can only be performed when the electrolyzer is empty or when the electrolyte circulation has stopped. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, there is a need for an improved method for detecting damaged membranes before energizing the electrolytic cell, i.e., before production of gases that could form explosive mixtures. [Means for solving the problem]

[0007] (Summary of the Invention) According to a broad aspect, there is provided a damage detection method for an electrolytic cell having a plurality of electrolytic cells, the method comprising: obtaining one or more first voltage measurements for each of the plurality of cells during shutdown of the electrolytic cell; performing a first classification of the plurality of cells into a first classification of cells having a damaged membrane and a second classification of cells not having a damaged membrane based on the one or more first voltage measurements; performing one or more first tests on the electrolytic cell to determine whether the first division of cells includes at least one cell, wherein at least one of the one or more first tests is based on injecting an inert gas into an anode and a cathode of each of the plurality of cells of the electrolytic cell; determining that results of the one or more first tests identify that the first section of cells includes the at least one cell; replacing the at least one cell; and performing a second test on the electrolytic cell to determine whether at least one additional cell having a damaged membrane remains in the electrolytic cell; determining that the results of the second test indicate that the at least one additional cell having a damaged membrane remains in the electrolytic cell; shutting down the electrolytic cell; and repeating the steps of performing the one or more first tests, replacing the at least one cell having a damaged membrane, and performing the second test; and determining that the results of the second test indicate that no further cells having damaged membranes remain in the electrolytic cell, and starting up the electrolytic cell.

[0008] In at least one embodiment according to any of the foregoing / other embodiments described herein, the method further includes performing the second test when the results of the one or more first tests determine that the first section of cells does not confirm that the at least one cell has the damaged membrane.

[0009] In at least one embodiment according to any previous / other embodiment described herein, performing the first classification of the plurality of cells comprises determining a cell current efficiency of the electrolyzer at the time of shutdown of the electrolyzer, the cell current efficiency being determined as a function of the time it takes for the voltage level of each cell of the electrolyzer to reach a predetermined generation voltage on a voltage curve after a polarization current is applied to the electrolyzer.

[0010] In at least one embodiment according to any previous / other embodiment described herein, determining the cell current efficiency includes using an equation having the following form: CE%=f(Δt) During the ceremony, CE% is the cell current efficiency of each cell of the electrolytic cell; Δt is the time it takes for the voltage level of each cell to switch from chlorine electrolysis to water electrolysis, and f is a nonlinear function of the parameters.

[0011] In at least one embodiment according to any of the foregoing / other embodiments described herein, the method further includes, after performing the first classification of the plurality of cells, providing an alarm indicating detection of a cell in the first category having the damaged membrane.

[0012] In at least one embodiment according to any previous / other embodiment described herein, the method further includes initiating maintenance of the electrolyzer after performing the first classification of the plurality of cells.

[0013] In at least one embodiment according to any of the foregoing / other embodiments described herein, the method further includes, after starting the electrolytic cell: obtaining one or more second voltage measurements for each of the plurality of cells of the electrolytic cell during the start-up of the electrolytic cell; performing a second classification of the plurality of cells into the first classification of cells having a damaged membrane and the second classification of cells not having a damaged membrane based on the one or more second voltage measurements; determining whether the first division of cells includes the at least one cell; repeating the steps of determining that the first section of cells includes the at least one cell; shutting down the electrolytic cell; and replacing the at least one cell and performing the second test to determine whether at least one additional cell having a damaged membrane remains in the electrolytic cell; and determining that the first section of cells does not include the at least one cell, and commencing normal operation of the electrolyzer.

[0014] In at least one embodiment according to any previous / other embodiment described herein, performing the second classification of the plurality of cells comprises determining a cell current efficiency of the electrolyzer at the start-up of the electrolyzer, the cell current efficiency being determined based on a look-up table correlating a range of current efficiencies for each cell with the time it takes for each cell to produce chlorine after a polarization current is applied to the electrolyzer.

[0015] In at least one embodiment according to any of the foregoing / other embodiments described herein, each cell of the electrolytic cell comprises at least the cathode, the anode, and a membrane between the cathode and the anode; and conducting the second test comprises injecting a first inert gas into the cathode of each cell of the electrolytic cell, injecting a second inert gas into the anode of each cell of the electrolytic cell, and comparing a concentration change rate of the inert gas mixture at the anolyte outlet of the electrolytic cell with a concentration change rate threshold; further wherein, for a given cell of the electrolytic cell, the rate of change of concentration of the inert gas mixture is greater than the threshold rate of change of concentration, indicating that the membrane of the given cell is damaged; and Further, where the location of the given cell is determined based on the time it takes for the concentration change rate of the inert gas mixture to exceed the concentration change rate threshold.

[0016] In at least one embodiment according to any previous / other embodiment described herein, the plurality of cells of the electrolytic cell is one of a plurality of chlor-alkali electrolysis cells and a plurality of non-alkaline water electrolysis cells.

[0017] According to yet another broad aspect, an assembly comprising: a plurality of electrolytic cells forming one or more electrolytic cells; and a damage detection system comprising at least one computing device operatively coupled to the one or more electrolytic cells; wherein the at least one computing device comprises at least one processing unit and a non-transitory computer-readable medium storing program instructions executable by the at least one processing unit to: assembly: obtaining one or more first voltage measurements for each of the plurality of cells during shutdown of the electrolyzer; performing a first classification of the plurality of cells into a first classification of cells having a damaged membrane and a second classification of cells not having a damaged membrane based on the one or more first voltage measurements; performing one or more first tests on the electrolytic cell to determine whether the first division of cells includes at least one cell, wherein at least one of the one or more first tests is based on injecting an inert gas into an anode and a cathode of each of the plurality of cells of the electrolytic cell; determining that results of the one or more first tests identify that the first section of cells includes the at least one cell; replacing the at least one cell; and performing a second test on the electrolytic cell to determine whether at least one additional cell having a damaged membrane remains in the electrolytic cell; determining that the results of the second test indicate that the at least one additional cell having a damaged membrane remains in the electrolytic cell; shutting down the electrolytic cell; and repeating the steps of performing the one or more first tests, replacing the at least one cell having a damaged membrane, and performing the second test; and determining that the results of the second test indicate that no further cells having damaged membranes remain in the electrolytic cell, and starting up the electrolytic cell.

[0018] In at least one embodiment according to any of the foregoing / other embodiments described herein, the one or more voltage measurements are obtained from at least one data acquisition and transmission (DAT) module communicatively coupled to the plurality of cells, the at least one DAT module configured to measure the voltages of the plurality of cells.

[0019] In at least one embodiment according to any of the foregoing / other embodiments described herein, the instructions are further executable to perform the second test by the at least one processing unit when the results of the one or more first tests determine that the first division of cells does not confirm that the at least one cell has the damaged film.

[0020] In at least one embodiment according to any previous / other embodiment described herein, the instructions are executable to perform the first classification of the plurality of cells by the at least one processing unit; the first classification includes using a cell classification and damage detection module communicatively coupled to the at least one DAT module for determining cell current efficiencies of the electrolyzer upon said shutdown of the electrolyzer; The cell current efficiency is determined as a function of the time it takes for the voltage level of each cell of the electrolytic cell to reach a predetermined development voltage on the voltage curve after a polarization current is applied to the electrolytic cell.

[0021] In at least one embodiment according to any previous / other embodiment described herein, the instructions are executable by the at least one processing unit to determine the cell current efficiency using an equation having the following form: CE%=f(Δt) During the ceremony, CE% is the cell current efficiency of each cell of the electrolytic cell; Δt is the time it takes for the voltage level of each cell to switch from chlorine electrolysis to water electrolysis, and f is a nonlinear function of the parameters.

[0022] In at least one embodiment according to any previous / other embodiment described herein, after performing the first classification of the plurality of cells, the instructions are further executable by at least one processing unit to provide an alarm indicating detection of a cell in the first classification having a damaged membrane and / or to initiate maintenance of the electrolyzer.

[0023] In at least one embodiment according to any previous / other embodiment described herein, after activating the electrolytic cell, the instructions are further executable by the at least one processing device to: obtaining one or more second voltage measurements for each of the plurality of cells of the electrolytic cell during the start-up of the electrolytic cell; performing a second classification of the plurality of cells into the first classification of cells having a damaged membrane and the second classification of cells not having a damaged membrane based on the one or more second voltage measurements; determining whether the first division of cells includes the at least one cell; repeating the steps of determining that the first section of cells includes the at least one cell; shutting down the electrolytic cell; and replacing the at least one cell and performing the second test to determine whether at least one additional cell having a damaged membrane remains in the electrolytic cell; and determining that the first section of cells does not include the at least one cell, and commencing normal operation of the electrolyzer.

[0024] In at least one embodiment according to any previous / other embodiment described herein, the instructions are executable by at least one processing unit to perform a second classification of the plurality of cells, including determining a cell current efficiency of the electrolytic cell upon start-up of the electrolytic cell; The cell current efficiency is determined based on a look-up table correlating the range of current efficiencies for each cell with the time it takes for each cell to produce chlorine after a polarization current is applied to the electrolyzer.

[0025] In at least one embodiment according to any of the foregoing / other embodiments described herein, each cell of the electrolytic cell comprises at least the cathode, the anode, and a membrane between the cathode and the anode; and the instructions are executable to perform the second test by at least one processing unit, the second test comprising injecting a first inert gas into the cathode of each cell of the electrolytic cell and injecting a second inert gas into the anode of each cell of the electrolytic cell, and using an inert gas leakage system coupled to a plurality of cells to compare a concentration change rate of the inert gas mixture at the anolyte outlet of the electrolytic cell with a concentration change rate threshold; and wherein for a given cell of the electrolytic cell, the rate of change of concentration of the inert gas mixture is greater than the threshold rate of change of concentration, indicating that the membrane of the given cell is damaged; And the location of the given cell is determined based on the time it takes for the rate of change of concentration of the inert gas mixture to exceed the rate of change of concentration threshold.

[0026] In at least one embodiment according to any previous / other embodiment described herein, the plurality of cells is one of a plurality of chlor-alkali electrolysis cells and a plurality of non-alkaline electrolysis cells.

[0027] The features of the systems, devices, and methods described herein can be used in various combinations according to the embodiments described herein. [Brief explanation of the drawings]

[0028] [Figure 1A] FIG. 1A is a flow chart of a method for detecting damaged membranes in electrochemical cells using inert gas injection. [Figure 1B] FIG. 1B is a flow chart of a method for detecting damaged membranes in electrochemical cells using inert gas injection. [Figure 2A] FIG. 2A is a schematic diagram of a system for conducting an inert gas leak test. [Figure 2B] FIG. 2B is a plot of helium gas concentration at the anolyte outlet header of FIG. 2A versus time elapsed since the start of helium gas injection at the catholyte outlet header of FIG. 2A. [Figure 3] FIG. 3 is a schematic diagram of a system for voltage measurement and classification of electrolytic cells. [Figure 4] FIG. 4 is a block diagram of an exemplary computer system for implementing the method of FIGS. 1A and 1B and / or the system of FIG. [Figure 5] 5A, 5B, 5C and 5D are diagrams of cell voltage and current profiles during start-up and shutdown of the electrolyzer.

[0029] It will be seen that throughout the accompanying drawings, like features are identified with like reference numerals. DETAILED DESCRIPTION OF THE INVENTION

[0030] (Detailed explanation) To avoid explosions or leaks of H2 / Cl2 or H2 / O2 in electrolysis cells, four methods are commonly used to detect damaged membranes. As used herein, the term "damaged" (or "damaged"), when used in reference to a membrane (e.g., a cation exchange membrane) in an electrochemical cell, means a membrane that is significantly defective or has failed. As used herein, a damaged membrane can be defined as one that contains pinholes that reduce the membrane's separation capabilities. Hydroxyl ions can migrate back into the anolyte compartment of the cell, causing losses in production. Also, if hydrogen enters the anode compartment, it can form an explosive mixture with chlorine.

[0031] In the first method, nitrogen gas (N2) is used to apply a differential pressure across the membrane. All valves are closed. A sudden drop in the differential pressure indicates membrane damage. However, this test cannot identify which membrane needs to be replaced for all operating cells, and the method is difficult to automate. This test also interferes with and delays the normal start-up procedure. All operations, such as electrolyte flow or heating, must be stopped. Because the electrolyzer is never empty, only major membrane damage at the very top of the membrane can be detected. During operation, the liquid level in the electrolyzer drops by 10% or more on the cathode side. Therefore, holes not detected by this test pose a safety risk during operation.

[0032] In the second method, nitrogen (N2) is added to the catholyte (catholyte) side of an empty electrolyzer. All valves are closed. If a sudden drop in differential pressure indicates membrane damage, gas exchange between multiple cells on the anode side is inhibited by flooding the inlet or outlet headers while the other cell connections are individually connected to the device and flow rates, such as leaked gas or pressure, are measured. This test is performed manually due to the cost of automating everything involving manual valves. Additionally, this test delays start-up for hours, with corresponding significant production losses. In particular, initial analysis of a drop in differential pressure across the electrolyzer can often lead to false positives when some membranes have minor, non-critical damage.

[0033] The third method involves starting the electrolyzer with a high nitrogen gas supply to dilute the hydrogen generated to a certain extent so that it does not exceed the explosion limit when mixed with the gas from the anode. The hydrogen concentration is analyzed at the anolyte outlet header. This test is usually automated. Nevertheless, this test cannot identify which cells have damaged membranes and need to be replaced. The residual risk of explosion depends on the response time of the analyzer. Since the electrolyzer is never empty, only major membrane damage at the very top of the membrane can be detected. During operation, the liquid level in the electrolyzer drops by 10% or more on the cathode side between low and high load operation. Therefore, holes not detected by this test pose a safety risk during operation.

[0034] The fourth method is based on the fact that the voltage of a cell with a damaged membrane drops faster after shutdown and rises slower during start-up compared to a cell with an intact membrane. This method is highly accurate and allows for accurate classification of the performance of individual membranes, allowing for the implementation of adequate countermeasures. This test can be easily automated. However, it requires shutting down and starting up the electrolyzer and does not completely eliminate the risk of starting up an electrolyzer with a damaged membrane after shutdown. Start-up with damaged membranes is only safe if sufficient nitrogen is added to dilute the hydrogen. The safe flow rate of nitrogen cannot be predicted, as it depends on the number of damaged membranes and on the severity of the damage to each membrane.

[0035] In a chlor-alkali plant, different methods can be combined depending on the assumed risk of having a damaged membrane. For example, if the electrolyzer shutdown is performed without abnormal pressure or pressure difference and no alarms resulting from the fourth method described above have occurred during the shutdown, the electrolyzer can be started up only by this fourth method. On the other hand, if the electrolyzer shutdown is not optimally controlled (e.g. due to insufficient control of pressure, etc.), the first method described above can be applied, and if this first method does not work, the second method can then be applied, otherwise the fourth method is used to start up the electrolyzer.

[0036] This specification describes a method and system for detecting defects (i.e., damage) in ion-exchange membranes operating in industrial-scale electrolyzers, such as chlor-alkali electrolyzers. It should be understood that the method and system described herein can also be used to detect damage in cell separators. The proposed method is based on inert leak gas analysis, preferably based on helium (He). In one embodiment, this method can be utilized during electrolyzer startup preparation, charging, or heat-up operating modes. Helium can be supplied to the cathode side via a nitrogen purge line and analyzed in the anolyte outlet header of the electrolyzer. If the helium concentration exceeds a given (predetermined) concentration threshold, the system and method described herein automatically shuts down the electrolyzer startup. In this way, it is possible to ensure accurate determination of the maximum expected peak concentration of hydrogen in the anode header of the electrolyzer during startup. Furthermore, by monitoring the leakage rate of the He / N mixture from the cathode side to the anode side during charging of the electrolyzer, the expected peak concentration during startup and full-load operation can be predicted.

[0037] In one embodiment, the proposed method can prevent the operation of an industrial electrolyzer with a defective membrane before gas production begins, in contrast to existing leak testing methods that can only be performed when the electrolyzer is empty or when the electrolyte circulation has stopped.

[0038] 1A and 1B illustrate a method 100 for detecting damaged membranes in an operating electrolyzer, according to one embodiment. In step 102, during load reduction (i.e., when the electrolyzer is shut down), a voltage measurement (referred to herein as a "first voltage measurement") is obtained in real time or near real time at each operating cell of the electrolyzer. The voltage measurements may be obtained using one or more data acquisition devices, such as one or more data acquisition and transmission (DAT) modules 301, which are further described below with reference to FIG. 3. Additionally, the one or more data acquisition devices sense the main electrolyzer current and acquire process measurements, such as the pH of the electrolyzer's brine inlet and the brine flow rate [m m ] to the electrolyzer. 3 / h]. In step 104, the data obtained in step 102 is analyzed to classify and detect operating cells having one or more damaged membranes. Based on the one or more first voltage measurements, a first classification of the plurality of cells into a first category of cells having damaged membranes and a second category of cells not having damaged membranes is performed in step 104. Step 104 can be performed using a computing device such as a cell classification and damage detection module 303, which is further described below with reference to FIG. 3. Also, as further described below with reference to FIGS. 5A and 5B, in one embodiment, step 104 of classifying and detecting one or more damaged membranes (during shutdown mode of the electrolyzer) may be based on an approximation of the current efficiency of a single cell of the electrolyzer using the duration required to reach a minimum voltage threshold.

[0039] In step 106, an indication of the presence of one or more damaged membranes may be output, for example, an alarm may be provided indicating the detection of one or more damaged membranes if one or more damaged membranes are detected in step 104. Maintenance of the electrolyzer may be initiated in step 108. Step 108 may involve performing any suitable action to initiate maintenance, including, but not limited to, inventory consultation, operator shift assignment, and equipment readiness or calibration.

[0040] In step 110, one or more first tests (referred to herein as confirmatory tests) are performed on the electrolytic cell to confirm the results of step 104. While step 110 is shown as being performed after steps 106 and 108, it should be understood that in some embodiments, step 110 may be performed immediately after step 104. According to one embodiment, a helium leak test is performed in step 110 to confirm the presence of the damaged film identified in step 104. In one embodiment, at least one of the one or more first tests (or confirmatory tests) is based on the injection of an inert gas at the anode and cathode of each cell of the electrolytic cell. In other alternative embodiments, the second and / or third detection methods described above may be implemented to perform the one or more confirmatory tests in step 110. Once the one or more confirmatory tests have been performed, an evaluation is performed in step 110 to determine whether the one or more confirmatory tests confirm the presence of the damaged film or films. If at least one of the one or more tests performed in step 110 identifies the presence of at least one damaged membrane, then the damaged membrane(s) may be replaced in a next step 112. Step 112 may include performing a disassembly / assembly operation to replace the at least one damaged membrane.

[0041] In step 114, a second test (referred to herein as an inert gas (e.g., helium) leak test) is performed on the electrolytic cell to detect any damaged membranes. In some embodiments, step 114 can be performed after the replacement operation in step 112. These replacement operations can cause membrane damage, for example, due to mechanical tension, twisting, etc. In other embodiments, step 114 can be performed to confirm the results of the one or more confirmatory tests performed in step 110 after one or more confirmatory tests in step 110 failed to confirm the presence of damaged membranes and it was determined that no replacement operation was performed in step 112. In some embodiments, the one or more confirmatory tests in step 110 may fail to confirm the presence of one or more damaged membranes by producing a false negative (failure to detect), for example, due to mishandling or improper operation of the electrolytic cell or its components. In this case, it may be desirable to perform the inert gas test in step 114 as a redundant step.

[0042] Subsequent evaluations are then performed in step 116 to re-determine whether one or more damaged films are detected after step 114 (i.e., based on the results of the inert gas test). If at least one damaged film is identified in step 116, operation of the electrolytic cell is stopped in step 118, and steps 110-116 can then be repeated until no damaged films are detected. In some embodiments, step 118 may include stopping operation of the electrolytic cell by interrupting the electrolytic cell start-up sequence or by interrupting the electrolytic cell start-up command, e.g., by interrupting electrolytic cell start-up in step 120. Otherwise, if no damaged films are detected in step 116, the electrolytic cell would be started in the next step 120, e.g., by turning on the power to the electrolytic cell.

[0043] In step 122, voltage measurements (referred to herein as "second voltage measurements") are obtained in real time or near real time at each operating cell of the electrolyzer during load ramp (i.e., during the ramp-up of the main current rectifier that occurs during start-up of the electrolyzer). The voltage measurements may be obtained using one or more data collection devices (e.g., DAT module 301) as described herein above with reference to step 102. In step 124, the data (i.e., voltage measurements) obtained in step 122 are analyzed to classify and detect operating cells having damaged membranes. In particular, based on the one or more second voltage measurements obtained in step 122, a second classification of the plurality of cells into a first classification of cells having damaged membranes and a second classification of cells not having damaged membranes is performed in step 124. 5C and 5D, in one embodiment, step 124 of classifying and detecting one or more damaged membranes (during the start-up operating mode of the electrolyzer) is based on approximating the current efficiency of a single cell of the electrolyzer using a theoretical look-up table, where each current efficiency range is associated with the time at which each cell begins to produce chlorine with the supplied current. Step 124 can be performed using any suitable computing device, such as the cell classification and damage detection module 303 described above with reference to step 104.

[0044] Next, method 100 may proceed to determine whether one or more damaged membranes are detected in step 126. In this case, if one or more damaged membranes are detected in step 126, an alarm may be provided, similar to step 106 described above. The electrolytic cell may then be shut down in step 128, and steps 112-126 may be repeated until no damaged membranes are detected. When it is determined in step 126 that no damaged membranes are detected, normal electrolytic cell operation may commence in the next step 130.

[0045] 2A , an embodiment of a system 200 for performing a helium leak test, such as in step 110 and / or step 114 of FIG. 1A , is described. As described above, a helium leak test can be performed using system 200 to identify the presence of a damaged membrane in a chlor-alkali electrolyzer, such as in chlor-alkali electrolysis cell 201. One or more components of system 200 can be controlled (e.g., using any suitable computing device, not shown) to perform the helium leak test. For example, the injection of an inert gas into cell 201 can be controlled via a computing device (e.g., a computer-implemented controller).

[0046] In the illustrated embodiment, the cell 201 includes a catholyte compartment 202, an anolyte compartment 204, and a membrane 206 separating the catholyte compartment 202 from the anolyte compartment 204. The cell 201 may include a catholyte inlet 208 and an anolyte inlet 210 for injecting an inert gas into the catholyte compartment 202 and the anolyte compartment 204, respectively. The inert gas may be injected when no electrolyte is present in the cell 201, for example, during operating modes including, but not limited to, start-up, filling, or heating of the electrolyzer. The catholyte inlet 208 may be provided at a first location in the catholyte compartment 202, and the anolyte inlet 210 may be provided at a second location in the anolyte compartment 204 that is different from the first location.

[0047] The cell 201 may further include a catholyte outlet header 212 and an anolyte outlet header 214 for injecting an inert gas into the catholyte compartment 202 and the anolyte compartment 204, respectively, and / or analyzing the concentration of the inert gas therein. The catholyte outlet header 212 may be provided in the catholyte compartment 202 at a third position different from the first and second positions, while the anolyte outlet header 214 may be provided in the anolyte compartment 204 at a fourth position different from the first, second, and third positions. In other words, the inert gas may be injected into their corresponding compartments 202 and 204 via the inlets 208 and 210, or, as the case may be, via the outlet headers 212 and 214. In particular, in one embodiment, the inert gas may be injected into the cell 201 via the inlets 208, 210 when no fluid is present in the electrolytic cell, and via the outlet headers 212, 214 when fluid is present in the electrolytic cell.

[0048] A test module 216 can be provided to analyze the concentration of the inert gas mixture in the cell 201. The test module 216 can be communicatively connected to any portion of the cell 210, such as the anolyte outlet header 214, via a communication link 218. The test module 216 can include, for example, a device for analyzing the concentration of the inert gas mixture. At least one sensor (not shown) can be provided in the test module 216 to measure the concentration of the inert gas. In some embodiments, the communication link 218 can include at least one communication cable, such as at least one coaxial cable, twisted pair cable, or fiber optic cable, among others. The test module 216 can include and / or be controlled via any suitable computing device.

[0049] 2A , catholyte inlet 208 can be used to inject a first inert gas 2201 into catholyte compartment 202, while anolyte inlet 210 can be used to inject a second inert gas 2202, different from first inert gas 2201, into anolyte chamber 204. In one embodiment, second gas 2202 can be injected simultaneously with first gas 2201. In one embodiment, first gas 2201 is helium and second gas 2202 is nitrogen. The nitrogen gas 2202 flow mixes with helium 222 that has leaked through membrane 206 and distributes the helium to anolyte outlet header 214, where the helium / nitrogen mixture concentration is analyzed by test module 216. According to one embodiment, if the helium concentration exceeds a predetermined or predefined limit, also referred to herein as a "concentration threshold" (e.g., 0.01% v / v), membrane 206 is presumed to be damaged and should be replaced. In alternative embodiments where a non-chlorine alkaline electrolysis cell is being tested, different predefined helium concentration limits may be used. In some embodiments, when system 200 is used to test a non-chlorine alkaline electrolysis cell, i.e., a non-chlorine alkaline electrolysis cell, including, but not limited to, a hydrochloric acid electrolysis cell, a non-alkaline water electrolysis cell, or a fuel cell, other inert gases, such as CO2, may be injected. Thus, although reference is made herein to cell 201 being a chlor-alkali electrolysis cell, it should be understood that the present invention is also applicable to non-chlor-alkali electrolysis cells.

[0050] According to an alternative embodiment, when electrolytic fluid (not shown) is present in the catholyte compartment 202 and the anolyte compartment 204 of the cell 201 (i.e., the cell 201 is at least partially filled with fluid), the cell 201 can be divided into a fluid-filled portion 224 and an empty portion 226 (i.e., the portion of the cell 201 emptied of any fluid). Because fluid is present in the electrolytic cell, helium gas 228 can be injected into the empty portion 226 of the catholyte compartment 202 through the catholyte outlet header 212 rather than through the catholyte inlet 208, and nitrogen gas 230 can be injected into the empty portion 226 of the anolyte compartment 204 through the anolyte outlet header 214 rather than through the anolyte inlet 210, allowing the nitrogen gas to mix with and disperse any helium that has leaked through the cell membrane 206. Thus, damage to the membrane in the empty portion 226 of the cell 201 can be detected (e.g., using the test module 216) when the concentration of the inert gas in the gas mixture in the anolyte outlet header 214 exceeds a predetermined limit.

[0051] By continuously monitoring the helium gas concentration in the anolyte outlet header 214, the location of membrane damage can be determined while the anolyte compartment 204 and catholyte compartment 202 of the cell 201 are filled. It also becomes possible to predict how the concentration of hydrogen in the chlorine will increase as the fluid level in the cell decreases during operation, as the cell current increases and the bubble zone on the top surface of the cell also increases.

[0052] According to a preferred embodiment, an inert gas test is performed on an assembly of many multiple electrolysis cells, where the flow rate of the first inert gas 2201 is less than the flow rate of the second inert gas 2202. The time it takes for the concentration change rate of the inert gas mixture to exceed a predetermined limit (i.e., a concentration change rate threshold) defines which electrolysis components in the assembly have severe damage.

[0053] 2B shows a plot 240 of helium gas concentration in the anolyte outlet header 214 versus time elapsed since the start of injection of helium gas 228 in the catholyte outlet header 212 in the catholyte compartment 202. As can be seen from plot 240, multiple step changes (such as 242 and 244) can occur in the increase in helium gas concentration. In one embodiment, the test module 216 may be configured to provide an alarm indicating the detection of one or more damaged membranes if a step change of more than 0.01% v / v is detected. If no step change is detected (i.e., if the increase in helium gas concentration is continuous), the test module 216 determines that no severely damaged membranes are present in the electrolytic cell. In the example shown in plot 240, an alarm is provided upon detection of step changes 242 and 244, both of which exceed the 0.01% v / v limit. The location of the damaged cell can then be determined (e.g., using the test module 216) based on the time it takes for the rate of change of the inert gas mixture concentration to reach a predetermined limit. 2B, the faster it takes the inert gas mixture to reach step change 242, the closer the damaged component is to test module 216. The longer it takes the mixture to reach step change 244, the farther the damaged component is from test module 216. Other embodiments may also be applied.

[0054] Referring now to FIG. 3, an embodiment of a system 300 for measuring and classifying electrolytic cell voltages will be described. The system 300 can be used to perform steps 102, 104, 122, and 124 of the method 100 described above with reference to FIGS. 1A and 1B. The system 300 includes a DAT module 301 that measures the differential cell voltage of an electrolytic cell 304. The DAT module 301 is configured to measure the differential cell voltage, either cathode-to-cathode or anode-to-anode, of the electrolytic cell 304 with a given accuracy, such as ±1 millivolt or any other suitable accuracy level. In one embodiment, the electrolytic cell 304 can include an industrial chlor-alkali electrolytic cell including multiple cells (not shown). In one embodiment, the cells can be provided in a series configuration, a parallel configuration, or a combination thereof. In some embodiments, the electrolytic cell 304 includes up to 160 cells. Other embodiments may also be applicable. Guard metal wiring 305 can be used to connect the input of each DAT module 301 to the cathode or anode terminal in an adjacent cell of the electrolytic cell 304. In some embodiments, each DAT module 301 can measure up to 32 voltage inputs associated with a given cell of the electrolytic cell 304. Each DAT module 301 can include multiple components, such as analog-to-digital converters, digital filters, memory buffers, and / or microcontrollers, and other components, to perform certain operations of data acquisition and transmission.

[0055] Data measured by DAT module 301 can be transmitted to data processing and communications module 302 using transmission link 306, this data being voltage measurements taken by DAT module 301 obtained according to steps 102 and 122 of FIGS. 1A and 1B. For purposes of illustration, transmission link 306 is shown in FIG. 3 as a wired connection between DAT module 301 and data processing and communications module 302. However, it should be understood that communication between DAT module 301 and data processing and communications module 302 can occur via a wired, wireless, or combination wired and wireless network. In one embodiment, the wireless network can include a personal area network (PAN), a local area network (LAN), a wireless local area network (WLAN), a metropolitan area network (MAN), a wide area network (WAN), or a combination thereof. The transmission link 306 may include any number of network devices, such as routers, modems, gateways, bridges, hubs, switches, and / or repeaters, communicatively connected to the DAT module 301 and the data processing and communications module 302 at any point along the network. In some embodiments, the transmission link 306 may be implemented using wireless broadcasting, where at least one transmitter, e.g., at least one of the DAT modules 301, may transmit data to at least one receiver, e.g., the data processing and communications module 302, via at least one antenna included in the at least one transmitter and / or at least one receiver. In other embodiments, the transmission link 306 may comprise at least one communications cable, e.g., a coaxial cable, a twisted pair cable, or a fiber optic cable, or other communications cable.

[0056] The data processing and communication module 302 can process data received from the DAT module 301 and send the data to the cell classification and damage detection module 303. In some embodiments, the data processing and communication module 302 can be communicatively connected to a shutdown relay 308, for example, the shutdown relay 308 of the electrolysis plant in which the electrolyzer 304 is operating. The data processing and communication module 302 can implement and send an emergency shutdown signal 307 to the shutdown relay 308. The shutdown relay 308 can be communicatively connected to a plant supervisory control and data acquisition (SCADA) system (not shown). When activated, the shutdown relay 308 can be used to initiate a shutdown of the electrolyzer 304. In some embodiments, the cell classification and damage detection module 303 can be remote from the location of the electrolyzer 304, the DAT module 301, the data processing and communication module 302, and / or the shutdown relay 308. In some embodiments, the cell classification and damage detection module 303 can comprise a cloud server. Furthermore, although shown as separate components, it should be understood that the data processing and communication module 302 and the cell classification and damage detection module 303 may be combined or integrated into a single component.

[0057] The data processing and communications module 302 can receive transformer-rectifier shunt current measurements from the DAT module 301, for example, using a 4-20 mA converter terminal (not shown) provided on the data processing and communications module 302. The data processing and communications module 302 can transmit voltage and current data streams sampled at a given rate, for example, once per second, to the cell classification and damage detection module 303. In some embodiments, the cell classification and damage detection module 303 can receive electrolysis process measurements from a third-party module 310 (such as a computer server), sometimes referred to as a distributed control system or DCS, including, but not limited to, catholyte outlet temperature, caustic soda outlet concentration, and inlet and / or outlet pH. According to one embodiment, the cell classification and damage detection module 303 can then be configured to classify electrolysis cells and detect one or more damaged membranes from the voltage measurements (and optionally, the data received from the third-party module 310) according to steps 104 and 124 of FIGS. 1A and 1B .

[0058] Referring to FIG. 4, a schematic diagram of an exemplary computing device 400 is shown. The computing device 400 can be used to implement one or more elements of the system 300 described above with reference to FIG. 3, including the method 100 described above with reference to FIGS. 1A and 1B, and / or part or all of the data processing and communication module 302, and / or part or all of the cell classification and impairment detection module 303. As shown, the computing device 400 includes at least one processing unit 402, a memory 404 storing instructions 406, and at least one input / output (I / O) interface (denoted as “input” and “output”). For simplicity, only one computing device 400 is shown, but a system may include more computing devices 400 operable by a user to access remote network resources and exchange data. The computing devices 400 may be the same or different types of devices. The components of computing device 400 may be connected in a variety of ways, including directly coupled, indirectly coupled via a network, and widely distributed and connected via a network (this is referred to as "cloud computing").

[0059] Each processing unit 402 may be, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, a programmable read-only memory (PROM), or any combination thereof.

[0060] The memory 404 may include any suitable combination of any type of computer memory located either internally or externally, such as, for example, random access memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically erasable programmable read-only memory (EEPROM), ferroelectric RAM (FRAM), etc.

[0061] The I / O interface allows the computing device 400 to interconnect with one or more input devices, such as a keyboard, mouse, camera, touch screen, and microphone, or with one or more output devices, such as a display screen and speakers.

[0062] In some embodiments, computing device 400 includes one or more network interfaces that enable computing device 400 to communicate with other components, exchange data with other components, access and connect to network resources, provide applications, and perform other computing applications by connecting to a network (or networks) capable of carrying other data, including the Internet, Ethernet, Plain Old Telephone Service (POTS) lines, Public Switched Telephone Network (PSTN), Integrated Services Digital Network (ISDN), Digital Subscriber Line (DSL), coaxial cable, fiber optic, satellite, mobile, wireless (e.g., Wi-Fi, WiMAX, etc.), SS7 signaling networks, fixed lines, local area networks, wide area networks, and any combination thereof.

[0063] 5A, 5B, 5C, and 5D, the voltage and current profiles of an electrolyzer cell are described according to one embodiment. The voltage and current profiles of the cell are illustrated when the membrane is faulty during electrolyzer shutdown (FIGS. 5A and 5B) and when the membrane is faulty during electrolyzer startup (FIGS. 5C and 5D).

[0064] As can be seen from FIGS. 5A and 5B, the rectified current 502 of the electrolyzer is equal to the normal operating load (I in FIG. 5A). normal ) to zero (0) kiloamperes, electrolyzer shutdown occurs. The voltage of a chlor-alkali electrolyzer cell with a damaged membrane drops rapidly (as shown by curve 504 in FIG. 5B ) compared to the voltage of an intact membrane, where for an intact membrane the voltage (shown by curves 504′, 504″) remains above the water electrolysis threshold during the polarization period (after shutting off the main current rectifier). According to one embodiment, classification of monitored cells into cells with damaged membranes and cells with intact membranes can be performed (as described above) during the shutdown mode of operation of the electrolyzer using the systems and methods described herein (e.g., in step 104 of FIG. 1A ). According to one embodiment of chlor-alkali electrolysis, classification of the severity of membrane damage is based on an automatic calculation of the current efficiency of each membrane during the shutdown period. The equation used to perform this calculation has the following form: CE%=f(Δt) (1) During the ceremony, CE%: membrane current efficiency of each cell constituting the electrolytic cell; Δt: the time it takes for the cell voltage to switch from chlorine electrolysis to water electrolysis, e.g., to 1.9 volts (506 in FIG. 5B); f: A nonlinear function relating to parameters defined using numerical simulation or laboratory data according to the design or technology of the electrolyzer before deployment in the production field.

[0065] According to one embodiment, membrane condition classification can be performed automatically in step 104 of method 100 described above with reference to FIGS. 1A and 1B by applying equation (1) to calculate the current efficiency of each cell of the electrolyzer during shutdown.

[0066] 5C and 5D show the voltage and current profiles of a single cell when the membrane is faulted during electrolyzer start-up. As shown in FIG. 5C, the electrolyzer start-up mode of operation occurs when the electrolyzer is energized with a rectified current load (as shown by curve 508 in FIG. 5C), where the current rises from zero kiloamperes into the normal operating range. The single voltage of a chlor-alkali electrolyzer cell with a damaged membrane (shown by curve 510 in FIG. 5D) is higher than the voltage of an unfaulted cell membrane at the equilibrium level of chlorine electrolysis (V in FIG. 5D). equilibrium 5D) (e.g., 2.2 volts), whereas the voltage of an unfaulted cell membrane (shown by curve 510' in FIG. 5D) can reach an equilibrium level more quickly. According to one embodiment of chlor-alkali electrolysis, automatic classification of the severity of membrane damage (e.g., as performed in step 124) can be based on an automatic approximation of the current efficiency of each membrane during the start-up period. In one embodiment, the current efficiency of a single cell for each membrane can be determined from a theoretical look-up table, where for each current efficiency range, the corresponding time when each cell begins to produce chlorine according to the supplied current is provided. The table is constructed based on a theoretical approximation of the chlorine produced versus time during start-up of the electrolyzer according to the cell design and technology. In step 122 of FIG. 1B, the corresponding time between energizing the electrolyzer with a rectified current and reaching the chlorine electrolysis equilibrium voltage level (e.g., 2.2 volts) is used to determine the current efficiency of each cell. Cells with current efficiencies below a predetermined threshold can be presumed to be operating with a damaged membrane.

[0067] Various aspects of the methods and systems described herein may be used alone, in combination, or in various configurations not specifically disclosed in the above embodiments, and therefore are not limited in their application to the details and arrangements of components set forth in the foregoing description or illustrated in the drawings. For example, aspects of one embodiment may be combined in any manner with aspects described in other embodiments. While specific embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications can be made without departing from the invention in its broader aspects. The scope of the following claims should not be limited by the embodiments described in the examples, but should be accorded the broadest reasonable interpretation consistent with the description as a whole.

Claims

1. A method for detecting damage to an electrolytic cell having a plurality of electrolytic cells, comprising: obtaining one or more first voltage measurements for each of the plurality of cells when the electrolytic cell is shut down; performing a first classification of the plurality of cells into a first classification of cells having a damaged film and a second classification of cells not having a damaged film based on the one or more first voltage measurements; performing one or more first tests on the electrolytic cell to determine whether the first division of cells includes at least one cell, wherein at least one of the one or more first tests is based on injecting an inert gas into an anode and a cathode of each of the plurality of cells of the electrolytic cell; determining that results of the one or more first tests identify that the first division of cells includes the at least one cell; replacing the at least one cell; and performing a second test on the electrolytic cell to determine whether at least one additional cell having a damaged membrane remains in the electrolytic cell; determining that the results of the second test indicate that the at least one additional cell having a damaged membrane remains in the electrolytic cell; shutting down the electrolytic cell; and repeating the steps of performing the one or more first tests, replacing the at least one cell having a damaged membrane, and performing the second test; and determining that the results of the second test indicate that no further cells having damaged membranes remain in the electrolytic cell, and starting up the electrolytic cell.

2. 2. The method of claim 1, further comprising: performing the second test when results of the one or more first tests determine that the first section of cells does not confirm that the at least one cell has a damaged membrane.

3. 3. The method of claim 1 or 2, wherein performing the first classification of the plurality of cells comprises determining a cell current efficiency of the electrolytic cell at the time of shutdown of the electrolytic cell, the cell current efficiency being determined as a function of the time it takes for the voltage level of each cell of the electrolytic cell to reach a predetermined generation voltage on a voltage curve after a polarization current is applied to the electrolytic cell.

4. 4. The method of claim 3, wherein determining the cell current efficiency comprises using an equation having the following form: CE% = f(Δt) During the ceremony, CE% is the cell current efficiency of each cell of the electrolytic cell; Δt is the time it takes for the voltage level of each cell to switch from chlorine electrolysis to water electrolysis, and f is a nonlinear function of the parameters.

5. 5. The method of claim 1, further comprising, after performing the first classification of the plurality of cells, providing an alarm indicating detection of a cell in the first category having a damaged membrane.

6. The method of any one of claims 1 to 5, further comprising initiating maintenance of the electrolyzer after performing the first classification of the plurality of cells.

7. The method of any one of claims 1 to 6, further comprising, after starting the electrolytic cell: obtaining one or more second voltage measurements for each of the plurality of cells of the electrolytic cell during the start-up of the electrolytic cell; performing a second classification of the plurality of cells into the first classification of cells having a damaged film and the second classification of cells not having a damaged film based on the one or more second voltage measurements; determining whether the first division of cells includes the at least one cell; repeating the steps of determining that the first section of cells includes the at least one cell; shutting down the electrolytic cell; and replacing the at least one cell and performing the second test to determine whether at least one additional cell having a damaged membrane remains in the electrolytic cell; and determining that the first section of cells does not include the at least one cell, and commencing normal operation of the electrolyzer.

8. 8. The method of claim 7, wherein performing the second classification of the plurality of cells includes determining a cell current efficiency of the electrolyzer during the start-up of the electrolyzer, the cell current efficiency being determined based on a look-up table correlating a range of current efficiencies for each cell with the time it takes for each cell to produce chlorine after a polarization current is applied to the electrolyzer.

9. each cell of the electrolytic cell comprising at least the cathode, the anode, and a membrane between the cathode and the anode; and conducting the second test comprises injecting a first inert gas into the cathode of each cell of the electrolytic cell, injecting a second inert gas into the anode of each cell of the electrolytic cell, and comparing a concentration change rate of the inert gas mixture at an anolyte outlet of the electrolytic cell with a concentration change rate threshold; further wherein, for a given cell of the electrolytic cell, the rate of change of concentration of the inert gas mixture is greater than the threshold rate of change of concentration, indicating that the membrane of the given cell is damaged; and Further, wherein the location of the given cell is determined based on the time it takes for the rate of concentration change of the inert gas mixture to exceed the concentration change rate threshold. The method according to any one of claims 1 to 8.

10. 10. The method of any one of claims 1 to 9, wherein the plurality of cells of the electrolyzer is one of a plurality of chlor-alkali electrolysis cells and a plurality of non-alkaline water electrolysis cells.

11. 1. An assembly comprising: a plurality of electrolytic cells forming one or more electrolytic cells; and a damage detection system comprising at least one computing device operatively coupled to the one or more electrolytic cells; wherein the at least one computing device comprises at least one processing unit and a non-transitory computer-readable medium storing program instructions executable by the at least one processing unit to: assembly: obtaining one or more first voltage measurements for each of the plurality of cells when the electrolytic cell is shut down; performing a first classification of the plurality of cells into a first classification of cells having a damaged film and a second classification of cells not having a damaged film based on the one or more first voltage measurements; performing one or more first tests on the electrolytic cell to determine whether the first division of cells includes at least one cell, wherein at least one of the one or more first tests is based on injecting an inert gas into an anode and a cathode of each of the plurality of cells of the electrolytic cell; determining that results of the one or more first tests identify that the first division of cells includes the at least one cell; replacing the at least one cell; and performing a second test on the electrolytic cell to determine whether at least one additional cell having a damaged membrane remains in the electrolytic cell; determining that the results of the second test indicate that the at least one additional cell having a damaged membrane remains in the electrolytic cell; shutting down the electrolytic cell; and repeating the steps of performing the one or more first tests, replacing the at least one cell having a damaged membrane, and performing the second test; and determining that the results of the second test indicate that no further cells having damaged membranes remain in the electrolytic cell, and starting up the electrolytic cell.

12. 12. The assembly of claim 11, wherein the one or more first voltage measurements are obtained from at least one data acquisition and transmission (DAT) module communicatively coupled to the plurality of cells, the at least one DAT module configured to measure voltages of the plurality of cells.

13. 13. The assembly of claim 11 or 12, wherein the instructions are further executable to perform the second test by the at least one processing unit when the results of the one or more first tests determine that the first section of cells does not confirm that the at least one cell has a damaged membrane.

14. the instructions are executable to perform the first classification of the plurality of cells by the at least one processing unit; the first classification includes using a cell classification and damage detection module communicatively coupled to the at least one DAT module for determining cell current efficiencies of the electrolyzer during the shutdown of the electrolyzer; the cell current efficiency is determined as a function of the time it takes for the voltage level of each cell of the electrolytic cell to reach a predetermined development voltage on a voltage curve after a polarization current is applied to the electrolytic cell; Assembly according to claim 12 or 13.

15. 15. The assembly of claim 14, wherein the instructions are executable by the at least one processing unit to determine the cell current efficiency using an equation having the following form: CE% = f(Δt) During the ceremony, CE% is the cell current efficiency of each cell of the electrolytic cell; Δt is the time it takes for the voltage level of each cell to switch from chlorine electrolysis to water electrolysis, and f is a nonlinear function of the parameters.

16. 16. The assembly of any one of claims 11 to 15, wherein the instructions are further executable by the at least one processing unit after performing the first classification of the plurality of cells to provide an alarm indicative of detection of a cell of the first category having a damaged membrane and / or to initiate maintenance of the electrolyzer.

17. 17. The assembly of any one of claims 11 to 16, wherein the instructions are further executable by the at least one processing device after starting the electrolytic cell to: obtaining one or more second voltage measurements for each of the plurality of cells of the electrolytic cell during the start-up of the electrolytic cell; performing a second classification of the plurality of cells into the first classification of cells having a damaged film and the second classification of cells not having a damaged film based on the one or more second voltage measurements; determining whether the first division of cells includes the at least one cell; repeating the steps of determining that the first section of cells includes the at least one cell; shutting down the electrolytic cell; and replacing the at least one cell and performing the second test to determine whether at least one additional cell having a damaged membrane remains in the electrolytic cell; and determining that the first section of cells does not include the at least one cell, and commencing normal operation of the electrolyzer.

18. the instructions are executable by at least one processing unit to perform a second classification of the plurality of cells, including determining a cell current efficiency of the electrolytic cell during the start-up of the electrolytic cell; the cell current efficiency is determined based on a look-up table correlating the range of current efficiencies for each cell with the time it takes for each cell to produce chlorine after a polarization current is applied to the electrolyzer; 18. The assembly of claim 17.

19. each cell of the electrolytic cell comprising at least the cathode, the anode, and a membrane between the cathode and the anode; and the instructions are executable to perform the second test by at least one processing unit, the second test comprising injecting a first inert gas into the cathode of each cell of the electrolytic cell and injecting a second inert gas into the anode of each cell of the electrolytic cell, and using an inert gas leakage system in communication with a plurality of cells to compare a concentration change rate of the inert gas mixture at an anolyte outlet of the electrolytic cell with a concentration change rate threshold; further wherein, for a given cell of the electrolytic cell, the rate of change of concentration of the inert gas mixture is greater than the threshold rate of change of concentration, indicating that the membrane of the given cell is damaged; Further, wherein the location of the given cell is determined based on the time it takes for the rate of concentration change of the inert gas mixture to exceed the concentration change rate threshold. Assembly according to any one of claims 11 to 18.

20. 20. The assembly of any one of claims 11 to 19, wherein the plurality of cells is one of a plurality of chlor-alkali electrolysis cells and a plurality of non-alkaline electrolysis cells.

Images