CN120344720A

CN120344720A - Method and system for detecting electrochemical cell damage using inert gas injection and dynamic differential pressure analysis

Info

Publication number: CN120344720A
Application number: CN202380085193.2A
Authority: CN
Inventors: 赫尔穆特·拉泽曼; 赛德·贝里赫; 乔治斯·西马德
Original assignee: Ruichechi 2000 Ltd
Current assignee: Ruichechi 2000 Ltd
Priority date: 2022-12-12
Filing date: 2023-12-11
Publication date: 2025-07-18
Also published as: JP2025541835A; WO2024124330A1; EP4634436A1

Abstract

A damage detection method for an electrolytic cell comprises classifying the cells of the electrolytic cell into a category having a damaged membrane, performing a first test to confirm whether the category includes at least one cell, at least one of the first tests being based on injecting an inert gas into the anode and cathode of each cell, and when the result of the first test confirms that the category includes the at least one cell, replacing the cell and performing a second test to evaluate whether there is at least one additional damaged cell; when the result of the second test indicates that there is at least one additional damaged cell, stopping the electrolytic cell and repeating the following steps: performing the first test, replacing the cell and performing the second test repeatedly, and starting the electrolytic cell when the result of the second test indicates that there are no more additional damaged cells.

Description

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

Cross Reference to Related Applications

The present application claims priority from U.S. patent application 63/431,857 filed 12 at 2022, 12, the entire contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates generally to industrial electrolytic cells, and more particularly to identifying damaged electrolytic cell membranes prior to starting a full operating cycle.

Background

An electrochemical cell (also referred to herein as a "battery") is a device that undergoes a chemical decomposition reaction by the application of an electrical current. This device is used to decompose salt (NaCl) into caustic (NaOH) and chlorine (Cl ₂). It is also used to decompose potassium chloride into potassium hydroxide and chlorine. Similar processes such as water electrolysis for the production of hydrogen are also performed using electrochemical cells.

In an industrial environment, a plurality of cells are reacted together in series or parallel. This combination is called an electrolyzer. Most industrial electrochemical cells consist of two electrodes (anode and cathode) and a membrane. In some cases, the membrane may also be referred to as a separator, a cell separator, a battery membrane, an exchange membrane, or an ion exchange membrane. When cations are exchanged through a membrane, the membrane may be referred to as a cation exchange membrane. The anode undergoes an oxidation reaction and the cathode undergoes a reduction reaction. In modern electrochemical cells, membranes such as ion exchange membranes are used to allow only the desired ions to migrate from one side of the reaction (anode) to the other (cathode). The efficiency and safety of industrial electrochemical cell operation is primarily related to the safety and efficiency of its components. More specifically, it relates to the safety and efficiency of cation exchange membranes. Although the cation exchange membrane has the characteristics of being efficient and environmentally friendly, it is very sensitive to contaminants at the inlet exceeding allowable concentrations and mechanical imperfections during installation or operation. The cation exchange separation efficiency can be severely affected by pinholes or cracks (also known as pinholes or pores). Some of the reasons for pinholes in the cell membrane include voids, bubbles and membrane detachment due to mechanical stress during maintenance and mainly by contamination of the electrolyte during shutdown and startup modes of operation. For example, the presence of pinholes in the membrane can affect the efficiency of the cell and the age of the cell in different ways, depending on the size and location of the pinholes (e.g., the portion of the cell where there is liquid or another portion where there is only gas). Pinholes may reduce the membrane separation capacity and thereby prevent hydroxyl ions from migrating back to the anolyte compartment. In general, no pinhole effect can be detected during normal operation unless corrosion of the anode coating occurs due to attack by caustic soda during chloralkali electrolysis. However, pinhole effects are evident at start-up or shut-down, as they can have an effect on the cell voltage. The decrease in separation efficiency of the ion exchange membrane may cause the mixing of gases such as H ₂ and Cl ₂ or H ₂ and O ₂, which may cause explosion or leakage of electrolyte that is fatal to humans and harmful to the environment.

It is well known to detect membrane damage by analyzing current-voltage curves during start-up and after shut-down of an electrolyzer. However, once the membrane is damaged, there is a risk of mixing the process gases, and an explosion may result. There is no way to ensure that when the cell is energized, an explosive mixture of gases from the anode side and the cathode side does not form. Well known membrane leakage tests can only be performed when the cell is empty or electrolyte circulation is stopped.

Thus, there is a need for improved methods to detect membrane damage prior to energizing the electrolyzer, i.e., prior to generating gases that may form explosive mixtures.

Disclosure of Invention

According to one broad aspect there is provided a method of damage detection for an electrolytic cell having a plurality of electrolytic cells, the method comprising obtaining one or more first voltage measurements of each of the plurality of cells during shutdown of the electrolytic cell, performing a first classification of the plurality of cells based on the one or more first voltage measurements to divide the plurality of cells into a first class of cells having a damaged membrane and a second class of cells without the damaged membrane, performing one or more first tests in the electrolytic cell to confirm whether the first class of cells includes at least one cell, at least one of the one or more first tests being based on an anode and a cathode of each of the plurality of cells, determining that a result of the one or more first tests confirms that the first class of cells includes at least one cell, replacing the at least one cell, and performing a second test in the electrolytic cell to confirm whether the one cell has the damaged membrane and a further one or more second tests are performed in the electrolytic cell, and a further step of the first test is performed to confirm that the one or more cells have the damaged membrane and a further step is not performed, and a further step of stopping the one or more first tests is performed in the electrolytic cell.

In at least one embodiment according to any of the preceding/other embodiments described herein, the method further comprises performing the second test upon determining that the results of the one or more first tests fail to confirm that the first type of battery comprises at least one battery having a damaged membrane.

In at least one embodiment according to any of the preceding/other embodiments described herein, the performing a first classification of the plurality of cells comprises determining a cell current efficiency of the electrolysis cell during shutdown of the electrolysis cell as a function of time required for a voltage level of each cell of the electrolysis cell to reach a predetermined point of occurrence in a voltage curve after triggering a polarization current in the electrolysis cell.

In at least one embodiment according to any of the preceding/other embodiments described herein, determining the battery current efficiency comprises using an equation having the form:

, wherein, Is the cell current efficiency of each cell of the electrolyzer,Is the time required for switching the voltage level of each cell from chlorine electrolysis to water electrolysis, andIs a parameterized nonlinear function.

In at least one embodiment according to any of the preceding/other embodiments described herein, the method further comprises, after performing the first classification on the plurality of cells, triggering an alarm indicating detection of the first type of cell with the damaged membrane.

In at least one embodiment according to any of the preceding/other embodiments described herein, the method further comprises initiating maintenance of the electrolytic cell after performing the first classification on the plurality of cells.

In at least one embodiment according to any of the preceding/other embodiments described herein, the method further comprises, after starting the electrolyzer, obtaining one or more second voltage measurements of each of the plurality of cells of the electrolyzer during the start-up of the electrolyzer, performing a second classification of the plurality of cells based on the one or more second voltage measurements to classify the plurality of cells into a first type of cells having a damaged membrane and a second type of cells without the damaged membrane, evaluating whether the first type of cells includes at least one cell, determining that the first type of cells includes the at least one cell, stopping the electrolyzer, and repeating the steps of replacing the at least one cell and performing the second test that evaluates whether there is at least one additional cell having the damaged membrane in the electrolyzer, and determining that the first type of cells does not include the at least one cell and continuing normal operation of the electrolyzer.

In at least one embodiment according to any of the preceding/other embodiments described herein, performing the second classification on the plurality of cells includes determining a cell current efficiency of the electrolysis cell during start-up of the electrolysis cell, the cell current efficiency determined based on a lookup table relating a current efficiency range of each cell of the electrolysis cell to a time required for each cell to generate chlorine after triggering a polarization current in the electrolysis cell.

In at least one embodiment according to any of the preceding/other embodiments described herein, each cell of the electrolyzer comprises at least a cathode, an anode, and a membrane between the cathode and the anode, and performing the second test comprises injecting a first inert gas at the cathode of each cell of the electrolyzer, injecting a second inert gas at the anode of each cell of the electrolyzer, and comparing a rate of change of concentration of an inert gas mixture at an anolyte outlet of the electrolyzer to a rate of change of concentration threshold, and for a given cell of the electrolyzer, a rate of change of concentration of the inert gas mixture greater than the rate of change of concentration threshold indicates that the membrane of the given cell has been damaged, and determining the location of the given cell based on the time required for the rate of change of concentration of the inert gas mixture to exceed the rate of change of concentration threshold.

In at least one embodiment according to any of the preceding/other embodiments described herein, 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.

According to another broad aspect, there is provided a combination comprising a plurality of electrolysis cells forming one or more electrolysis cells; and a damage detection system comprising at least one computing device operatively connected to the one or more cells, the at least one computing device comprising at least one processing unit and a non-transitory computer readable medium having stored thereon program instructions for execution by the at least one processing unit for acquiring one or more first voltage measurements of each of a plurality of cells during shutdown of the cell, performing a first classification of the plurality of cells based on the one or more first voltage measurements to classify the plurality of cells into a first class of cells having a damaged membrane and a second class of cells without the damaged membrane, performing one or more first tests in the cell to confirm whether the first class of cells includes at least one cell, the at least one first test of the one or more first tests being based on anode and cathode injection inert gas injection into each of the plurality of cells during the cell shutdown, determining whether the first cell or the plurality of cells has a damaged membrane and a second class of cells having a further result of the one or more tests being repeated, and evaluating whether the at least one first test of the cells has been replaced in the cell and the cell has been replaced in the cell, and determining that the result of the second test indicates that there are no more cells in the cell that have the damaged membrane and starting the cell.

In at least one embodiment according to any of the preceding/other embodiments described herein, the one or more first voltage measurements are obtained from at least one Data Acquisition and Transmission (DAT) module communicatively connected to the plurality of batteries, the at least one DAT module configured to measure voltages of the plurality of batteries.

In at least one embodiment according to any of the preceding/other embodiments described herein, the instructions are further executable by the at least one processing unit to perform the second test when it is determined that the results of the one or more first tests fail to confirm that the first type of battery comprises at least one battery having a damaged membrane.

In at least one embodiment according to any of the preceding/other embodiments described herein, the instructions are executable by the at least one processing unit to perform the first classification of the plurality of cells, including using a cell classification and damage detection module communicatively connected to the at least one DAT module to determine a cell current efficiency of the electrolysis cell during shutdown of the electrolysis cell as a function of time required for a voltage level of each cell of the electrolysis cell to reach a predetermined point of occurrence in a voltage curve after triggering a polarization current in the electrolysis cell.

In at least one embodiment according to any of the preceding/other embodiments described herein, the instructions are executable by the at least one processing unit for determining the battery current efficiency using a formula having the form:

In at least one embodiment according to any of the preceding/other embodiments described herein, the instructions are further executable by the at least one processing unit to trigger an alarm indicating detection of the first type of cell with the damaged membrane and/or initiate maintenance of the electrolytic cell after performing the first classification on the plurality of cells.

In at least one embodiment according to any of the preceding/further embodiments described herein, the instructions are further executable by the at least one processing unit to, after starting the electrolyzer, obtain one or more second voltage measurements for each of the plurality of cells of the electrolyzer during the electrolyzer start, perform a second classification of the plurality of cells based on the one or more second voltage measurements to divide the plurality of cells into a first type of cells having a damaged membrane and a second type of cells without the damaged membrane, evaluate whether the first type of cells includes at least one cell, determine that the first type of cells includes the at least one cell, stop the electrolyzer, and repeat the steps of replacing the at least one cell and performing the second test that evaluates whether there is at least one additional cell in the electrolyzer having the damaged membrane, and determine that the first type of cells does not include the at least one cell and continue normal operation of the electrolyzer.

In at least one embodiment according to any of the preceding/other embodiments described herein, the instructions are further executable by the at least one processing unit to perform the second classification on the plurality of cells, including determining a cell current efficiency of the electrolysis cell during start-up of the electrolysis cell, the cell current efficiency determined based on a look-up table relating a current efficiency range of each cell of the electrolysis cell to a time required for each cell to generate chlorine after triggering a polarization current in the electrolysis cell.

In at least one embodiment according to any of the preceding/other embodiments described herein, each cell of the electrolyzer comprises at least a cathode, an anode, and a membrane between the cathode and the anode, and the instructions are executable by the at least one processing unit for performing the second test comprising injecting a first inert gas at the cathode of each cell of the electrolyzer using an inert gas leak test system connected to the plurality of cells, injecting a second inert gas at the anode of each cell of the electrolyzer, and comparing a rate of change of concentration of an inert gas mixture at an anolyte outlet of the electrolyzer to a rate of change of concentration threshold, and for a given cell of the electrolyzer, the rate of change of concentration of the inert gas mixture being greater than the rate of change of concentration threshold indicates that the membrane of the given cell has been damaged, and determining a location of the given cell based on a time required for the rate of change of concentration of inert gas mixture to exceed the rate of concentration threshold.

In at least one embodiment according to any of the preceding/other embodiments described herein, the plurality of cells is one of a plurality of chlor-alkali electrolysis cells and a plurality of non-alkaline water electrolysis cells.

The features of the systems, devices, and methods described herein may be used in various combinations according to the embodiments described herein.

Drawings

FIGS. 1A and 1B are flowcharts of a method for detecting a damaged membrane in an electrochemical cell using inert gas injection;

FIG. 2A is a schematic diagram of a system for performing an inert gas leak test, and

FIG. 2B is a graph of helium concentration over time for the anolyte outlet header of FIG. 2A, starting with helium injection from the catholyte outlet header of FIG. 2A;

FIG. 3 is a schematic diagram of an electrolytic cell voltage measurement and classification system;

FIG. 4 is a block diagram of an example computing system implementing the methods of FIGS. 1A and 1B and/or the system of FIG. 3;

Fig. 5A, 5B, 5C and 5D are graphs of cell voltage and current during startup and shutdown of the electrolyzer.

Note that in the drawings, like features are identified by like reference numerals.

Detailed Description

Four methods are commonly used to detect damaged membranes to avoid H ₂/Cl₂ -or H ₂/O₂ -explosions or electrolyte cell leaks. As used herein, the term "damaged" (or "damaged") when used in relation to a membrane (e.g., a cation exchange membrane) of an electrochemical cell refers to a membrane that has serious defects or malfunctions. As used herein, a damaged membrane may be defined as a membrane containing pinholes which reduce the separation capacity of the membrane. Product losses result from hydroxyl ions migrating back to the cell anolyte compartment. In addition, hydrogen gas can also enter the anode compartment and form an explosive mixture with chlorine gas.

In the first method, a pressure differential is applied across the membrane with nitrogen (N ₂). All valves are closed. A rapid drop in pressure differential indicates membrane damage. However, this test does not determine which membranes in all operating cells need replacement and this approach is also difficult to automate. The test also interrupts and delays the routine start-up procedure. All operations such as flow of the electrolyte or heating should be stopped. Since the cell is not empty, only large areas of membrane damage at the top of the membrane can be detected. In operation, the liquid level in the cathode side of the cell drops by more than 10%. Thus, holes that are not detected by this test may become a safety hazard in operation.

In the second method, nitrogen (N ₂) is applied to the catholyte side of the empty cell. All valves are closed. If the rapid drop in pressure differential indicates membrane damage, gas exchange between the anode side cells is inhibited by flooding the inlet or outlet headers, while a device is connected at the other cell junction to measure the flow or pressure of the leaking gas, etc., respectively. This test is performed manually because of the high automation costs of all the associated manual valves. Furthermore, this method delays the start-up time by several hours, with a corresponding significant production loss. In particular, if there is little non-critical damage to the membranes, preliminary analysis of the drop in pressure differential across the cell tends to result in false positive detection.

In a third method, the electrolyzer is started up with a large nitrogen feed to dilute the hydrogen produced so that it does not exceed the explosion limit when mixed with the gas from the anode. At the anolyte outlet header, the hydrogen concentration was analyzed. Such testing is typically automated. However, this test does not determine which cells have a damaged membrane and need replacement. The remaining risk of explosion depends on the reaction time of the analyzer. Since the cell is not empty, only large areas of membrane damage at the top of the membrane can be detected. In operation, the liquid level at the cathode side of the cell drops by more than 10% between low load and high load operation. Thus, holes that are not detected by this test may become a safety hazard in operation.

In the fourth method, the battery voltage with the damaged film drops faster after shutdown and rises later during startup than the battery without the damaged film. This method is highly sensitive and allows accurate classification of the properties of the individual films, so that appropriate countermeasures can be taken. Such testing can be easily automated. However, this requires stopping or starting the electrolyzer and does not completely avoid the risk of starting the electrolyzer with damaged membranes after a shutdown. The start-up of the damaged membrane is safe only if sufficient nitrogen is applied to dilute the hydrogen. The safe flow of nitrogen cannot be predicted because it depends on the number of damaged membranes and the severity of the individual membrane damage.

Chlor-alkali plants can combine different approaches depending on the assumed risk of damaged membranes. For example, if no abnormal pressure or pressure difference occurs when the electrolytic cell performs a shutdown and the fourth method described above does not issue an alarm during the shutdown, the electrolytic cell may be started using only the fourth method. On the other hand, if the cell shutdown control is not ideal (e.g., due to insufficient pressure control, etc.), the first method described above may be employed, and if the first method fails, the second method may be employed, and otherwise, the fourth method may be employed to start the cell.

Described herein are methods and systems for detecting defects (i.e., damage) in ion exchange membranes operating in industrial scale electrolytic cells, such as chlor-alkali electrolytic cells. It should be understood that the methods and systems described herein may also be used to detect damage in battery separators. The proposed method is based on inert leakage gas analysis, preferably helium (He). In one embodiment, the method may be used during preparation of the electrolyzer start-up, fill or heat mode of operation. Helium may be supplied to the cathode side via a nitrogen purge line and analyzed at the anolyte outlet header of the electrolysis cell. If the helium concentration is above a given (predetermined) concentration threshold, the systems and methods described herein will automatically prevent the start-up of the electrolyzer. In this way, it is ensured that the maximum expected peak concentration of hydrogen in the anode header of the electrolyzer at start-up is accurately determined. Monitoring the leak rate of the He/N ₂ mixture from the cathode to the anode side during cell filling also predicts the expected peak concentration during start-up to full load operation.

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

Fig. 1A and 1B illustrate a method 100 of detecting a damaged membrane in an operating electrolyzer according to one embodiment. In step 102, a voltage measurement (referred to herein as a "first voltage measurement") is obtained for each operating cell of the electrolyzer during load reduction (i.e., during electrolyzer shutdown) in real time or in pseudo-real time. 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, may be used to obtain the voltage measurements. The data acquisition device may also sense the main cell current and obtain process measurements such as, but not limited to, cell brine inlet pH and cell feed brine flow [ m ³/h ]. In step 104, the data acquired in step 102 is analyzed to classify and detect the operating battery with the damaged membrane. In step 104, a first classification of the plurality of cells into a first type of cells having damaged membranes and a second type of cells having no damaged membranes is performed based on the one or more first voltage measurements. Step 104 may be performed using a computer device, such as battery classification and damage detection module 303, which is further described below with reference to fig. 3. As will be further described below with reference to fig. 5A and 5B, in one embodiment, the step 104 of classifying and detecting a damaged membrane (during the cell shutdown mode of operation) may be based on an approximation of the individual cell current efficiency of the cell using the duration of time required to reach the minimum voltage threshold.

In step 106, an indication that a damaged film is present may be output, e.g., if a damaged film is detected in step 104, an alarm indicating that a damaged film was detected may be triggered. Maintenance of the electrolytic cell may be initiated in step 108. Step 108 may involve any suitable action performed to initiate maintenance, including, but not limited to, inventory consultation, operator shift scheduling, and equipment preparation or calibration, etc.

In step 110, one or more first tests (referred to herein as validation tests) are performed in the electrolysis cell to verify the results of step 104. Although 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 determined in step 104. In one embodiment, at least one first (or validation) test is based on the injection of inert gas at the anode and cathode of each cell of the electrolyzer. In other alternative embodiments, the second and/or third detection methods described above may perform a validation test in step 110. Once the validation test is performed, an evaluation is made in step 110 to determine whether the validation test validates the presence of the damaged film. If at least one test performed in step 110 confirms the presence of at least one damaged film, then the next step 112 may be to replace the damaged film. Step 112 may include performing a disassembly/assembly activity to replace at least one damaged membrane.

In step 114, a second test (referred to herein as an inert gas (e.g., helium) leak test) is performed in the electrolyzer to detect if there are any damaged membranes. In some embodiments, step 114 may be performed after the replacement activity of step 112. These replacement activities may lead to membrane damage, e.g. due to mechanical tension, torsion, etc. In other embodiments, step 114 may determine in step 110 that the validation test fails to confirm whether a damaged film is present and is performed after no replacement activity is performed in step 112 to confirm the results of the validation test performed in step 110. In some embodiments, the validation test of step 110 may fail to confirm the presence of a damaged membrane because of the occurrence of a false negative, e.g., due to improper handling or mishandling of the electrolyzer or its components. In this case, it may be necessary to perform an inert gas test in step 114 as a redundant step.

A subsequent evaluation is then performed in step 116 to re-evaluate whether one or more damaged films were detected after step 114 (i.e., based on the results of the inert gas test). If at least one damaged membrane is identified in step 116, operation of the electrolyzer is stopped in step 118 and steps 110 to 116 may then be repeated until the damaged membrane is no longer detected. In some embodiments, step 118 may include stopping operation of the electrolyzer by interrupting the electrolyzer-activation sequence or preventing electrolyzer-activation instructions, such as the electrolyzer-activation of step 120. Otherwise, if no damaged membrane is detected in step 116, the next step 120 is to start the electrolyzer, for example by turning on the electrolyzer power.

In step 122, a voltage measurement (referred to herein as a "second voltage measurement") is taken in real time or pseudo-real time at each operating cell of the electrolyzer during an increase in load (i.e., during a ramp up of the main current rectifier that occurs during startup of the electrolyzer). Voltage measurements may be obtained using one or more of the data acquisition devices (e.g., DAT module 301) described above with reference to step 102. In step 124, the data acquired in step 122 (i.e., voltage measurements) is analyzed to classify and detect the operating battery with the damaged membrane. Specifically, in step 124, a second classification of the plurality of cells into a first type of cells having damaged membranes and a second type of cells having no damaged membranes is performed based on the one or more second voltage measurements obtained in step 122. As will be further described below with reference to fig. 5C and 5D, in one embodiment, the step 124 of classifying and detecting damaged membranes (during the start-up mode of operation of the electrolyzer) is based on an approximation of the individual cell current efficiency of the electrolyzer using a theoretical look-up table in which each current efficiency range is associated with the time at which each cell starts to produce chlorine according to the feed current. Step 124 may be performed using any suitable computing device, such as the battery classification and damage detection module 303 described above with reference to step 104.

The method 100 may then evaluate whether a damaged film is detected in step 126. If this is the case and one or more damaged films are detected in step 126, an alarm may be triggered similar to step 106 described above. The cell is then stopped in step 128 and steps 112 to 126 are repeated until the damaged membrane is no longer detected. When it is determined in step 126 that no damaged membrane is detected, the next step 130 will continue with normal cell operation.

Referring now to fig. 2A, one embodiment of a system 200 for performing a helium leak test (such as step 110 and/or step 114 of fig. 1A) will be described. As described above, a helium leak test may be performed using the system 200 to confirm the presence of damaged films in a chlor-alkali cell, such as chlor-alkali cell 201. One or more components of the system 200 may be controlled (e.g., using any suitable computing device, not shown) to perform the helium leak test. For example, the injection of inert gas into the battery 201 may be controlled by a computing device (e.g., a computer-implemented controller).

In the illustrated embodiment, the cell 201 includes a catholyte chamber 202, an anolyte chamber 204, and a membrane 206 separating the catholyte chamber 202 and the anolyte chamber 204. The cell 201 may be provided with a catholyte inlet 208 and an anolyte inlet 210 for injecting inert gas into the catholyte chamber 202 and the anolyte chamber 204, respectively. Inert gas may be injected when the cell 201 is empty of all electrolyte, for example during modes of operation including, but not limited to, cell start-up, filling, or heating. Catholyte inlet 208 may be disposed at catholyte chamber 202 at a first location, and anolyte inlet 210 may be disposed at anolyte chamber 204 at a second location different from the first location.

Cell 201 may further be provided with a catholyte outlet header 212 and an anolyte outlet header 214 for injecting inert gas into catholyte chamber 202 and anolyte chamber 204, respectively, and/or analyzing the inert gas concentration therein. Catholyte outlet header 212 may be disposed at catholyte chamber 202 at a third location different from the first and second locations, and anolyte outlet header 214 may be disposed at anolyte chamber 204 at a fourth location different from the first, second, and third locations. In other words, inert gas may be injected into the respective chambers 202 and 204 via both inlets 208 and 210, and in some cases, outlet headers 212 and 214. In particular, in one embodiment, inert gas may be injected into cell 201 via inlets 208 and 210 when there is no liquid in the electrolyzer, and inert gas may be injected into cell 201 via outlet headers 212 and 214 when there is liquid in the electrolyzer.

A test module 216 may be provided for analyzing the concentration of the inert gas mixture in the battery 201. Test module 216 may be communicatively coupled to any portion of cell 210, such as anolyte outlet header 214, via communication link 218. For example, the test module 216 may include a device for analyzing the concentration of the inert gas mixture. The test module 216 may be provided with at least one sensor (not shown) for measuring the concentration of the inert gas. In some embodiments, the communication link 218 may 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 may include and/or be controlled via any suitable computing device.

In one embodiment shown in fig. 2A, catholyte inlet 208 may be used to inject a first inert gas 220 ₁ into catholyte chamber 202, while anolyte inlet 210 may be used to inject a second inert gas 220 ₂, different from first inert gas 220 ₁, into anolyte chamber 204. In one embodiment, the second gas 220 ₂ may be injected simultaneously with the first gas 220 ₁. In one embodiment, the first gas 220 ₁ is helium and the second gas 220 ₂ is nitrogen. The flow of nitrogen 220 ₂ will mix and disperse the leaked helium 222 through the membrane 206 to the anolyte outlet header 214 where the concentration of the helium/nitrogen mixture is analyzed by the test module 216. According to one embodiment, if the helium concentration is above a predetermined or predetermined limit, also referred to herein as a "concentration threshold" (e.g., 0.01% v/v), then the membrane 206 is assessed as damaged and should be replaced. In alternative embodiments of testing non-chlor-alkali electrolysis cells, different preset limits for helium concentration may be used. In some embodiments, if the system 200 is used to test non-chlor-alkali cells, including but not limited to hydrochloric acid cells, non-alkaline water cells, or fuel cells, other inert gases, such as CO ₂, may be injected. Thus, although the battery 201 is referred to herein as a chlor-alkali cell, it should be understood that non-chlor-alkali cells are equally suitable.

According to another embodiment, when electrolyte (not shown) is present in catholyte chamber 202 and anolyte chamber 204 of cell 201 (i.e., cell 201 is at least partially filled with electrolyte), cell 201 may be divided into electrolyte fill 224 and void 226 (i.e., the portion of cell 201 that is free of any electrolyte). Because of the presence of electrolyte in the cell, helium gas 228 may be injected into the void 226 of catholyte chamber 202 via catholyte outlet header 212 instead of via catholyte inlet 208, and nitrogen gas 230 may be injected into the void 226 of anolyte chamber 204 via anolyte outlet header 214 instead of via anolyte inlet 210 to mix and disperse helium gas leaking through cell membrane 206. Thus, when the concentration of inert gas in the gas mixture at anolyte outlet header 214 is above a predetermined limit, membrane damage to void 226 of cell 201 may be detected (e.g., using test module 216).

The location of the membrane damage can be determined by continuous monitoring of the helium concentration at anolyte outlet header 214 as anolyte chamber 204 and catholyte chamber 202 of cell 201 are filled. As the current of the cell increases and the foam area at the top of the cell also increases, it is also possible to calculate the way in which the hydrogen concentration in the chlorine will increase with decreasing liquid level in the cell during operation.

According to a preferred embodiment, the inert gas test is performed in a combination of a plurality of electrolysis cells, wherein the flow rate of the first inert gas 220 ₁ is lower than the flow rate of the second inert gas 220 ₂. The time required for the concentration change rate of the inert gas mixture to exceed a predetermined limit (i.e., the concentration change rate threshold) determines which electrolytic components in the assembly are severely damaged.

Fig. 2B shows a graph 240 of helium concentration at anolyte outlet header 214 over time starting with helium 228 injected at catholyte outlet header 212 disposed at catholyte chamber 202. As can be seen in graph 240, the increase in helium concentration may occur in multiple step changes (e.g., 242 and 244). In one embodiment, the test module 216 may be configured to trigger an alarm indicating detection of a damaged membrane if a step change of greater than 0.01% v/v is detected. If no step change is detected (i.e., a continuous increase in helium concentration), the test module 216 determines that there is no severely damaged membrane in the electrolyzer. In the example shown in graph 240, an alarm is triggered when step changes 242 and 244 are detected that are both above the limit of 0.01% v/v. The location of the damaged cell may then be determined (e.g., using test module 216) based on the time required for the concentration rate of change of the inert gas mixture to reach a predetermined limit. With continued reference to the example shown in FIG. 2B, the faster the inert gas mixture takes to reach the step change 242, the closer the damaged component is to the test module 216. The longer it takes for the mixture to reach the step change 244, the farther the damaged component is from the test module 216. Other embodiments may also be suitable.

Referring now to fig. 3, an embodiment of an electrolytic cell voltage measurement and classification system 300 will be described. The system 300 may be used to perform the steps 102, 104, 122, and 124 of the method 100 described above with reference to fig. 1A and 1B. The system 300 includes a DAT module 301 for measuring differential cell voltages of an electrolytic cell 304. The DAT module 301 is configured to measure the cathode-to-cathode or anode-to-anode differential cell voltage in the electrolyzer 304 with a given accuracy (e.g., +/-1 millivolt or any other suitable level of accuracy). In one embodiment, the electrolytic cell 304 may comprise an industrial chlor-alkali electrolytic cell having a plurality of cells (not shown). In one embodiment, the cells may be arranged in a serial configuration, a parallel configuration, or a combination thereof. In some embodiments, the electrolyzer 304 comprises up to 160 cells. Other embodiments may also be suitable. A protected wire 305 may be used to connect the input of each DAT module 301 to the terminal of the cathode or anode of an adjacent cell in the electrolyzer 304. In some embodiments, each DAT module 301 can measure up to 32 voltage inputs associated with a given cell of the electrolyzer 304. The DAT module 301 may each include a plurality of components, such as an analog-to-digital converter, a digital filter, a memory buffer, and/or a microcontroller to perform data acquisition and transmission routines, etc.

The data measured by the DAT module 301 may be transmitted to the data processing and communication module 302 using a transmission link 306, which obtains the voltage measurements collected by the DAT module 301 according to steps 102 and 122 of fig. 1A and 1B. For illustration, the transmission link 306 in fig. 3 is shown as a wired connection between the DAT module 301 and the data processing and communication module 302. However, it should be understood that the communication between the DAT module 301 and the data processing and communication module 302 may be implemented by wire, wireless, or a combination of wire and wireless networks. In one embodiment, the wireless network may 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, etc. in communication with the DAT module 301 and the data processing and communication module 302 at any location along the network. In some embodiments, the transmission link 306 may be implemented using wireless broadcasting, wherein at least one transmitter, such as the at least one DAT module 301, may transmit data to at least one receiver (e.g., the data processing and communication module 302) via at least one antenna provided with the at least one transmitter and/or the at least one receiver. In other embodiments, the transmission link 306 may include at least one communication cable, such as a coaxial cable, a twisted pair cable, or a fiber optic cable, among others.

The data processing and communication module 302 may process the data received from the DAT module 301 and transmit the data to the battery classification and damage detection module 303. In some embodiments, the data processing and communication module 302 may be communicatively coupled to a trip relay 308, such as the trip relay 308 of an electrolysis plant in which the electrolysis cell 304 is operating. The data processing and communication module 302 may execute and send an emergency stop signal 307 to the cut relay 308. The trip relay 308 may be communicatively coupled to a plant monitoring and data acquisition (SCADA) system (not shown). When activated, the trip relay 308 may be used to initiate shutdown of the electrolytic cell 304. In some embodiments, the battery classification and damage detection module 303 may be located remotely from the electrolyzer 304, the DAT module 301, the data processing and communication module 302, and/or the disconnect relay 308. In some embodiments, the battery classification and damage detection module 303 may include a cloud server. Further, it should be understood that although shown as separate components in the figures, the data processing and communication module 302 and the battery classification and damage detection module 303 may be combined or integrated as one component.

The data processing and communication module 302 may receive the transformer rectifier shunt current measurement from the DAT module 301, for example, using 4-20 milliamp converter terminals (not shown) provided on the data processing and communication module 302. The data processing and communication module 302 may broadcast to the battery classification and damage detection module 303 a voltage and current data stream sampled at a given rate (e.g., one point per second). In some embodiments, the battery classification and damage detection module 303 may receive electrolytic process measurement data including, but not limited to, electrolyte outlet temperature, caustic outlet concentration, and inlet and/or outlet pH values from a third party module 310 (e.g., a computer server) (sometimes referred to as a distributed control system or DCS). According to one embodiment, the battery classification and damage detection module 303 may be configured to classify the electrolytic cells and detect damaged films from the voltage measurements (and optionally data received from the third party module 310), as shown in steps 104 and 124 of fig. 1A and 1B.

Referring to FIG. 4, a schematic diagram of an example computing device 400 is shown. The computing device 400 may be used to implement the method 100 described above with reference to fig. 1A and 1B and/or one or more elements of the system 300 described above with reference to fig. 3, including part or all of the data processing and communication module 302 and/or part or all of the battery classification and damage detection module 303. As shown, computing device 400 includes at least one processor 402, memory 404 storing instructions 406, and at least one input/output (I/O) interface (shown as "input" and "output"). For simplicity, only one computing device 400 is shown, but the system may include more computing devices 400 that are operable by a user to access remote network resources and exchange data. Computing device 400 may be the same or different types of devices. The elements of computing device 400 may be connected in a variety of ways including direct connection, indirect connection via a network, distributed over a wide geographic area, and connected via a network (which may be referred to as "cloud computing").

For example, each processor 402 may be any type of general purpose microprocessor or microcontroller, digital Signal Processing (DSP) processor, integrated circuit, field Programmable Gate Array (FPGA), reconfigurable processor, programmable Read Only Memory (PROM), or any combination thereof.

For example, memory 404 may include any suitable combination of types of computer memory, such as 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), electrically erasable programmable read-only memory (EEPROM), ferroelectric RAM (FRAM), and the like, internal or external.

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

In some embodiments, computing device 400 includes one or more network interfaces to enable computing device 400 to communicate with other components, to exchange data with other components, to access and connect network resources, to provide services to applications, and to execute other computing applications by connecting to a network (or networks) capable of transmitting data, including the Internet, ethernet, plain-time-service (POTS) lines, public Switched Telephone Networks (PSTN), integrated Services Digital Networks (ISDN), digital Subscriber Lines (DSL), coaxial cables, fiber optics, satellites, mobile, wireless (e.g., wi-Fi, wiMAX), SS7 signaling networks, fixed lines, local area networks, wide area networks, and other networks, as well as any combination of these networks.

Referring now to fig. 5A, 5B, 5C, and 5D, the electrolyzer cell voltage and current curves according to one embodiment are described. The cell voltage and current curves are shown at membrane failure during cell shutdown (fig. 5A and 5B) and at membrane failure during cell startup (fig. 5C and 5D).

As can be seen from fig. 5A and 5B, when the rectified current 502 of the electrolyzer drops from normal operating load (labeled I _{Normal state )} in fig. 5A to zero (0) kiloamp), the electrolyzer is shut down, the voltage of the chlor-alkali electrolyzer cell with the damaged membrane may drop rapidly (as shown by curve 504 in fig. 5B) as compared to an undamaged membrane where the voltage may remain at a level greater than the water electrolysis threshold during polarization (after the main current rectifier is shut off.) according to one embodiment of chlor-alkali electrolysis, the classification of the severity of the membrane failure is based on an automatic calculation of the current efficiency of each membrane during shutdown, the system and method described herein (e.g., step 104 of fig. 1A) may be used during the electrolyzer shutdown mode of operation (as described above):

(1)

Wherein:

membrane current efficiency of each cell constituting the electrolytic cell;

The time 506 (of fig. 5B) required for the cell voltage to switch from chlorine electrolysis to water electrolysis, for example at 1.9 volts;

depending on the design or technology of the electrolyzer, a parameterized nonlinear function defined by numerical simulation or laboratory data is used prior to production site deployment.

According to one embodiment, the film classification may be automatically performed in step 104 of the method 100 described above with reference to fig. 1A and 1B by employing equation (1) to calculate the current efficiency of each cell of the electrolyzer during shutdown.

Fig. 5C and 5D show individual cell voltage and current curves at membrane failure during startup of the electrolyzer. As shown in fig. 5C, when the electrolyzer is energized with a rectifier current load (as shown by curve 508 in fig. 5C), the electrolyzer start-up mode of operation is entered where the current increases from zero kilo-amperes to the normal operating range. A single voltage of a chlor-alkali cell with a damaged membrane (as shown by curve 510 in fig. 5D) requires a longer time 512 to reach the voltage balance level of the chlor-electrolysis (labeled V _Balancing in fig. 5D) (e.g., 2.2 volts) than a non-faulty cell membrane where the voltage (as shown by curve 510' in fig. 5D) may reach the balance level faster. According to one embodiment of chlor-alkali electrolysis, the automatic classification of the severity of membrane failure (e.g., performed in step 124) may be based on an automatic approximation of the current efficiency of each membrane during start-up. In one embodiment, the individual cell current efficiency for each membrane may be determined by a theoretical look-up table in which a corresponding time is provided for each current efficiency range, i.e., the time each cell begins to produce chlorine in accordance with the feed current. The table is built based on theoretical approximations of chlorine gas generated during start-up of the electrolyzer versus time, according to cell design and technology. In step 122 of fig. 1B, the current efficiency of each cell is determined using the time correspondence between energizing the electrolyzer by rectifying the current and reaching a chlorine electrolysis equilibrium voltage level (e.g., 2.2 volts). Cells with current efficiencies below a predetermined threshold may be evaluated as operating with a damaged membrane.

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

Claims

1. A damage detection method for an electrolytic cell having a plurality of electrolytic cells, the method comprising:

Acquiring one or more first voltage measurements for each of a plurality of cells during a shutdown of the electrolyzer;

Performing a first classification of the plurality of cells based on the one or more first voltage measurements to classify the plurality of cells into a first type of cells having a damaged membrane and a second type of cells without the damaged membrane;

performing one or more first tests in the electrolyzer to confirm whether the first type of cell includes at least one cell, at least one of the one or more first tests being based on the injection of inert gas at the anode and cathode of each of the plurality of cells of the electrolyzer;

determining that the results of the one or more first tests confirm that the first type of cell includes at least one cell, replacing the at least one cell, and performing a second test in the electrolytic cell to evaluate whether there is at least one additional cell in the electrolytic cell having the damaged membrane;

Determining that the result of the second test indicates that there is at least one additional cell with the damaged membrane in the electrolytic cell, stopping the electrolytic cell, and repeating the steps of performing the one or more first tests, replacing at least one cell with the damaged membrane, and performing the second test, and

The results of the second test were determined to indicate that there were no more cells with the damaged membrane in the cell and the cell was started.

2. The method of claim 1, further comprising performing the second test upon determining that the results of the one or more first tests fail to confirm that the first type of battery includes at least one battery having a damaged membrane.

3. The method of claim 1 or claim 2, wherein the performing a first classification of the plurality of cells comprises determining a cell current efficiency of the electrolysis cell during shutdown of the electrolysis cell as a function of a time required for a voltage level of each cell of the electrolysis cell to reach a predetermined point of occurrence in a voltage curve after triggering a polarization current in the electrolysis cell.

4. The method of claim 3, wherein determining the battery current efficiency comprises using an equation having the form:

5. The method of any of claims 1-4, further comprising, after performing the first classification on the plurality of batteries, triggering an alarm indicating detection of the first type of battery with the damaged membrane.

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

7. The method of any one of claims 1 to 6, further comprising, after starting up the electrolyzer:

During start-up of the electrolyzer, obtaining one or more second voltage measurements for each of the plurality of cells of the electrolyzer;

performing a second classification of the plurality of cells based on the one or more second voltage measurements to classify the plurality of cells into a first type of cells having a damaged membrane and a second type of cells without the damaged membrane;

evaluating whether the first type of battery includes at least one battery;

Determining that the first type of cell includes the at least one cell, stopping the electrolytic cell, and repeating the steps of replacing the at least one cell and performing the second test that evaluates whether there is at least one additional cell with the damaged membrane in the electrolytic cell, and

Determining that the first type of cell does not include the at least one cell and continuing normal operation of the electrolyzer.

8. The method of claim 7, wherein performing the second classification on the plurality of cells comprises determining a cell current efficiency of the electrolysis cell during start-up of the electrolysis cell, the cell current efficiency determined based on a lookup table that correlates a current efficiency range of each cell of the electrolysis cell to a time required for each cell to generate chlorine after triggering a polarization current in the electrolysis cell.

9. The method of any one of claims 1 to 8, wherein each cell of the electrolyzer comprises at least a cathode, an anode, and a membrane between the cathode and the anode, and performing the second test comprises injecting a first inert gas at the cathode of each cell of the electrolyzer, injecting a second inert gas at the anode of each cell of the electrolyzer, and comparing a rate of change in concentration of an inert gas mixture at an anolyte outlet of the electrolyzer to a rate of change of concentration threshold, further wherein, for a given cell of the electrolyzer, a rate of change of concentration of the inert gas mixture greater than the rate of change of concentration threshold indicates that the membrane of the given cell has been damaged, and further wherein a location of the given cell is determined based on a time required for the rate of change of concentration of the inert gas mixture to exceed the rate of change of concentration threshold.

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. A combination, comprising:

A plurality of electrolysis cells forming one or more electrolysis cells, and

A damage detection system comprising at least one computing device operatively connected to the one or more electrolytic cells, the at least one computing device comprising at least one processing unit and a non-transitory computer readable medium having stored thereon program instructions for execution by the at least one processing unit to

12. The combination 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 batteries, the at least one DAT module configured to measure voltages of the plurality of batteries.

13. The combination of claim 11 or 12, wherein the instructions are further executable by the at least one processing unit to perform the second test when it is determined that the results of the one or more first tests fail to confirm that the first type of battery comprises at least one battery having a damaged membrane.

14. The combination of claim 12 or 13, wherein the instructions are executable by the at least one processing unit to perform the first classification of the plurality of cells, including using a cell classification and damage detection module in communication with the at least one DAT module to determine a cell current efficiency of the electrolysis cell during shutdown of the electrolysis cell as a function of time required for a voltage level of each cell of the electrolysis cell to reach a predetermined point of occurrence in a voltage curve after triggering a polarization current in the electrolysis cell.

15. The combination of claim 14, wherein the instructions are executable by the at least one processing unit to determine the battery current efficiency using a formula having the form:

16. The combination of any one of claims 11 to 15, wherein the instructions are further executable by the at least one processing unit for triggering an alarm indicating detection of the first type of cell with the damaged membrane and/or initiating maintenance of the electrolytic cell after performing the first classification on the plurality of cells.

17. The combination according to any one of claims 11-16, wherein the instructions are further executable by the at least one processing unit for, after starting up the electrolytic cell:

evaluating whether the first type of battery includes at least one battery;

18. The combination of claim 17, wherein the instructions are further executable by the at least one processing unit to perform the second classification on the plurality of cells, including determining a cell current efficiency of the electrolysis cell during start-up of the electrolysis cell, the cell current efficiency determined based on a lookup table that correlates a current efficiency range of each cell of the electrolysis cell with a time required for each cell to generate chlorine after triggering a polarization current in the electrolysis cell.

19. The combination of any of claims 11-18, wherein each cell of the electrolyzer comprises at least a cathode, an anode, and a membrane between the cathode and the anode, and wherein the instructions are executable by the at least one processing unit for performing the second test comprising injecting a first inert gas at the cathode of each cell of the electrolyzer using an inert gas leak test system connected to the plurality of cells, injecting a second inert gas at the anode of each cell of the electrolyzer, and comparing a concentration rate of the inert gas mixture at an anolyte outlet of the electrolyzer to a concentration rate threshold, further wherein for a given cell of the electrolyzer, a concentration rate of the inert gas mixture is greater than the concentration rate threshold indicating that the membrane of the given cell has been damaged, and further wherein the location of the given cell is determined based on the time required for the concentration rate of the inert gas mixture to exceed the concentration rate threshold.

20. The combination according to 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 water electrolysis cells.