JP2007523259A - Hydrogen generation system and method - Google Patents

Abstract

【Task】
An electrochemical system having a plurality of individual electrochemical cell stacks is described. The system includes a water-oxygen management system that is fluidly passed through a plurality of electrochemical cell stacks and a hydrogen management system that is fluidly passed through a plurality of electrochemical cells. There are means for ventilating the system and a control system for monitoring and operating the electrochemical system, the control system detecting means for abnormal operating conditions, and reducing the performance of the electrochemical system according to the abnormal conditions It has a means to do.
[Selection] Figure 2

Description

  The present invention relates to electrochemical cell systems, and more particularly to the use of multiple electrochemical cells in a single system.

BACKGROUND OF THE INVENTION Electrochemical cells are energy conversion devices and are usually classified as either electrolytic cells or fuel cells. The electrolytic cell functions as a hydrogen generator by electrolyzing water to generate hydrogen gas and oxygen gas, and functions as a fuel cell that generates electric power by electrochemically reacting hydrogen with oxygen. Referring to FIG. 1, some details of a typical proton exchange membrane electrolysis cell are shown. In a normal anode feed water electrolysis cell (not shown), treated water is supplied to the cell next to the oxygen electrode (in the electrolysis cell, the anode) to produce oxygen gas, electrons and protons. The electrolytic reaction is facilitated by the positive terminal of the power source electrically connected to the anode and the negative terminal of the power source connected to the hydrogen electrode (the cathode in the electrolysis cell).

  Part of the oxygen gas and treated water exits the cell, and protons and water move through the proton exchange membrane to the cathode where hydrogen gas is produced. In a cathode supply electrolysis cell (not shown), treated water is sent to a hydrogen electrode, and a portion of this water moves from the cathode through the membrane to the anode where protons and oxygen gas are produced. Part of the treated water leaves the cell on the cathode side without passing through this membrane. Protons travel through this membrane to the cathode where hydrogen gas is produced. A typical electrochemical cell system comprises a plurality of individual cells arranged in a stack and a working fluid introduced into the cell via input and output conduits formed in the stack structure. The cells in the stack are arranged in order, each comprising a cathode, a proton exchange membrane, and an anode.

  In conventional configurations, the anode, cathode, or both are gas diffusion electrodes that facilitate diffusion of gas into the membrane. Each cathode / membrane / anode assembly (hereinafter “membrane electrode assembly” or “MEA”) is typically supported on both sides by a flow field comprising a screen pack or bipolar plate. Such a flow field facilitates fluid movement and membrane hydration and provides mechanical support to the MEA. Since there is often a differential pressure within the cell, a compression pad or other compression means is often used to maintain uniform compression within the active area of the cell, i.e., the electrode, thereby reducing the fluid field and the cell. Intimate contact between the electrodes is maintained over a long period of time. Reactants and products are moved using pumps to and from electrochemical cells connected to liquid and gas storage devices by pipe systems. The use of both this external pump and storage area limits the ease of transfer of the electrochemical cell and complicates the use of the electrochemical cell in places where it is difficult to install or operate the pump and storage tank. become. While existing electrochemical cell systems are suitable for their intended purpose, there is still room for improvement, particularly in the operation of electrochemical cell systems with multiple electrochemical cell stacks and their operation.

SUMMARY OF THE INVENTION An electrochemical system having a plurality of separate electrochemical cell stacks. The system includes a water-oxygen management system that is fluidly passed through a plurality of electrochemical cell stacks and a hydrogen management system that is fluidly passed through a plurality of electrochemical cell stacks. Means for ventilating the system, a control system for monitoring and operating the electrochemical system, the control system for detecting an abnormal operating condition, and means for reducing the performance of the electrochemical system in response to the abnormal condition; With

  An electrochemical system having a plurality of individual electrochemical cell stacks comprising an oxygen-water phase separator in fluid communication with the plurality of electrochemical cell stacks. The phase separator includes a first manifold that discharges water into the electrochemical cell stack and a second manifold that receives water from the electrochemical cell stack. The first manifold includes a plurality of cell stack outlets for releasing water into the electrochemical cell and a guard bed outlet. An exhaust conduit is in fluid communication with the phase separator, the conduit having an inlet for receiving a gas stream from the phase separator and an exhaust port for discharging the gas stream. The system also includes a flow reducer coupled to the first manifold guard bed outlet. This flow reducer limits the amount of water passing through the guard bed outlet beyond the pressure range.

  A system for automatically calibrating a combustible gas sensor having a user interface and a control panel coupled to the user interface. There is a premixed combustible gas canister and at least one combustible gas sensor electrically connected to the control panel. A valve structure is provided through which liquid passes through the canister and at least one combustible gas sensor. The valve structure is also electrically connected to the control panel.

  A method for automatically calibrating a combustible gas sensor, the step of automatically releasing a premixed combustible gas at a predetermined interval, and the step of injecting the premixed combustible gas into a detection surface of the combustible gas sensor; With The level of combustible gas detected by this sensor is measured, and sensor calibration is automatically adjusted according to this measurement.

  A system for controlling the output pressure of an electrochemical system comprising at least one electrochemical cell. There is a pressure regulator having a set point, which is in fluid communication with the electrochemical cell. The pressure sensor is in fluid communication with the pressure regulator between the pressure regulator and the electrochemical cell. The control panel monitors the pressure sensor and the means for adjusting the output of the electrochemical cell in response to the pressure sensor, and the gas pressure of the pressure sensor is maintained at a predetermined pressure that is equal to or higher than the set point of the pressure regulator.

DETAILED DESCRIPTION Hydrogen gas is widely used in industry and is a versatile material with energy applications ranging from ammonia generation, generator cooling to rocket power driving space. While hydrogen gas is the most abundant element in the universe, it is not readily available and must be extracted from other materials. Usually, a large amount of hydrogen gas is produced using a mass production facility that reforms methane through a steam reduction process, stored in a container or tank, and transported to the customer according to the application.

  Due to logistics and security issues, it has become more desirable to produce hydrogen closer to the final point of use. The most desirable production method is that the hydrogen can be produced when needed at the point of use by the user. In order to realize this, a hydrogen generator using electrolysis of water is used to generate hydrogen gas when necessary. With reference to FIGS. 1 and 2, an electrochemical system 12 of the present invention is shown. The electrochemical cell 14 typically comprises one or more individual cells arranged in a stack and a working fluid introduced through the cells in the stack structure. The cells in the stack are sequentially arranged, and each has a cathode, a proton exchange membrane, and an anode (hereinafter referred to as “membrane electrode assembly” or “MEA” 119) as shown in FIG. Typically, each cell further comprises a first flow field in fluid communication with the cathode and a second flow field in liquid communication with the anode. The MEA 119 is supported on either or both sides by screen packs placed in these flow fields, or by bipolar plates, and allows membrane hydration and / or fluid flow to and from the MEA 119. It can be configured to facilitate movement.

  Membrane 118 preferably comprises a solid phase or gel electrolyte under the operating conditions of the electrochemical cell. Practical materials include, for example, proton conducting ionomers and ion exchange resins. Practical proton conducting ionomers include alkali metal salts, alkaline earth metal salts, protonic acids, complexes comprising protonic acid salts, or mixtures comprising one or more of the complexes mentioned above. Counter ions that are practical for the above salts include halogen ions, perchlorate ions, thiocyanate ions, trifluoromethanesulfonate ions, fluoroborate ions, and others. Representative examples of such salts include, but are not limited to, lithium fluoride, sodium iodide, lithium iodide, lithium perchloride, sodium thiocyanide, lithium trifluoromethanesulfonate, lithium borofluoride, six There are lithium fluorophosphate, phosphoric acid, sulfuric acid, trifluoromethanesulfonic acid and others. The alkali metal salt, alkaline earth metal salt, proton acid, or proton acid salt may be one or more polar polymers such as polyether, polyester, or polyimide, or a network polymer containing the above polar polymer as a segment. Alternatively, it can be synthesized with a crosslinked polymer. Practical polyethers include polyoxyalkylenes such as polyethylene glycol, polyethylene glycol monoether, and polyethylene glycol diether; poly (oxyethylene-co-oxypropylene) glycol, poly (oxyethylene-co-oxypropylene) glycol At least one copolymer of the aforementioned polyethers, such as monoethers and poly (oxyethylene-co-oxypropylene) glycol diethers; condensation products of ethylenediamine with the aforementioned polyoxyalkylenes; and phosphates; There are esters of the above-mentioned polyoxyalkylenes such as aliphatic carboxylate esters or aromatic carboxylate esters. For example, a copolymer such as polyethylene glycol monoethyl ether and methacrylic acid is useful because it exhibits sufficient ionic conductivity.

  Practical ion exchange resins as proton conductive materials include hydrocarbon and fluorocarbon type resins. Hydrocarbon type ion exchange resins include phenol resins, condensation resins such as phenol-formaldehyde, polystyrene, styrene-divinylbenzene copolymer, styrene-butadiene copolymer, styrene, styrene-divinylbenzene-vinyl chloride terpolymer, There are others, which can be fully impregnated using the cation exchange capacity by sulfonation, or they can be sufficiently impregnated using the anion exchange capacity by converting to the corresponding quaternary amine after chloromethylation. Can be made.

  Examples of the perfluorohydrocarbon type ion exchange resin include tetrafluoroethylene-perfluorosulfonylethoxyvinyl ether, tetrafluoroethylene-hydroxylated (perfluorovinyl ether) copolymer, and other hydrates. For example, if oxidation and / or acid resistance is required, such as a fuel cell cathode, a fluorocarbon type resin having sulfonic acid, carboxylic acid and / or phosphoric acid functional groups is preferred. Fluorohydrocarbon type resins usually show good acid resistance with halogens, strong acids and bases. One family of fluorohydrocarbon type resins having sulfonic acid functional groups is NAFION® resin (commercially available from EI du Pont de Nemours and Company, Wilmington, Del.) It is.

  Electrodes 114 and 116 comprise a catalyst suitable for performing the necessary electrochemical reaction (ie, electrolyzing water to generate hydrogen and oxygen). Suitable electrodes include, but are not limited to, platinum, palladium, rhodium, carbon, gold, tantalum, tungsten, ruthenium, iridium, osmium, etc., and alloys with one or more of the above metals. It is. The electrodes 114 and 116 can be formed on the membrane 118 or are layered in contact with or in ionic communication with the membrane 118 in the vicinity of the membrane 118.

  The flow field member (not shown) and the support membrane 118 create a passage for the system fluid and are preferably electrically conductive, for example, a screen pack or a bipolar plate. The screen pack comprises one or more perforated sheets or woven mesh formed of metal or strands. These screens typically include, for example, metals such as niobium, zirconium, tantalum, titanium, carbon steel, stainless steel, nickel, cobalt, and also combinations of alloys and one or more of the above metals. . Bipolar plates are generally fiber carbon, polytetrafluoroethylene, or PTFE (commercially available under the trade name TEFLON® from EI du Pont de Nemours and Company, Wilmington, Del.) It is a porous structure comprising fiber carbon impregnated with.

  Referring to FIGS. 2 and 3, after the water is decomposed into hydrogen gas and oxygen gas in the electrochemical cell 14, each gas remains in the electrochemical cell 14 for further downstream processing. Oxygen mixed with treated water that has not been decomposed is sent to a water-oxygen management system 16 (hereinafter referred to as “WOMS”). WOMS 16 maintains all of its functions as a water liquid in the electrochemical system 12, including separating oxygen gas from water, manifolding the water line, monitoring water quality, and deionizing water. To do. All these functions are described in more detail below.

  Hydrogen gas exits the electrochemical cell 14 with a small amount of water carried over with hydrogen protons during the process of electrolyzing the water. This hydrogen-water mixture is sent to a hydrogen gas management system 18 (hereinafter “HGMS”) for further processing. The HGMS 18 separates the water from the hydrogen gas and treats this gas with additional drying equipment to further minimize water contamination. Eventually, hydrogen gas exits system 12 through port 20 and is ready for use in the final application.

  The electrochemical system 12 further includes subsystems such as a ventilation system 22, a power supply module 24, a control panel 26, a user input panel 28, and a combustion gas sensor calibration system 30. The cabinet 32 of the electrochemical system 12 is divided by a partition 34 that separates the electrical compartment 36 from the gas generating compartment 38, preventing hydrogen gas from being inadvertently exposed to the ignition source.

  WOMS 16 is best shown in FIGS. Deionized water is sent from an external source to the phase separator and water manifold 40 via a water inlet conduit 42. An additional filter 44 is connected to the water inlet conduit 42 to further protect contaminants from entering the system 12. When the system 12 is started, water enters through the conduit 42 and fills the phase separator body 46 until the desired level of water that closes the solenoid valve 50 is detected by the sensor 48. In operation, when the water level sensor 48 detects that the water level of the phase separator has fallen below a predetermined threshold, the solenoid valve 50 opens to provide additional water to the system. The phase separator and water manifold 40 are attached to the cabinet by brackets 43.

  When the appropriate water level is reached and the system 12 is in operation, water is discharged from the phase separator body 46 via conduit 52 and pump 54. An additional heat exchanger 56 may be used to reduce the water temperature. With the pump 54 left, water enters the manifold 58 via the conduit 60. A plurality of outlets 62 and 64 provide water to the electrochemical cell 14 and the guard bed 66. The outlet 62 pumps water through the flow switch 133 and through the conduit 68 to the electrochemical cell 14. The flow switch 133 is electrically connected to the control circuit of the power supply 24. If the flow is interrupted in the conduit 68, the flow switch sends a signal to the power supply 24, and the interrupted conduit disconnects power to the electrochemical cell 14 that was providing water. Additional water that is not directed to the electrochemical cell 14 exits the manifold 58 via the outlet 64 and is filtered by the guard bed 66. As will be described in more detail below, the guard bed 66 includes a restrictor that prevents excessive flow through the outlet 64 and operates in reverse to prevent shortage of water in the electrochemical cell 14 that reduces operating life. Like to do. The manifold 58 also includes a conduit sensor 70 that measures the quality of water in the system 12. This sensor 70 is typically a water conduit and temperature sensor (commercially available as model RC-20 / PS102J2 manufactured by Pathfinder Instruments). Since these types of sensors require water to flow to maintain precise measurements, the location of the sensor 70 is important. By installing the sensor 70 at the end of the manifold 58 near the exit to the guard bed 66, the sensor 70 can perform two functions. The first is that the sensor 70 measures water quality. When the water quality is typically 1 to 5 microsiemens / cm and the predetermined threshold falls below a normal value, the system 12 shuts down to prevent contamination that damages the electrochemical cell 14. Further, since the sensor 70 needs to have water flowing for accurate measurement, if either the guard bed or a conduit or valve attached thereto is clogged, the water will not flow, and the conductive sensor 70 Indicates that there is a problem with the system 12 and that it should read the high conductivity illegally and shut down the process.

  As water enters outlet 64, it moves to guard bed 66 via conduit 72. The guard bed 66 includes a manifold 73 that receives water from the conduit 72 and applies force to the water through a screen 74 that filters any particulate matter from the body 75 of the guard bed 66. After being processed in the body 75, the water exits the guard bed 66 through the manifold 73 and through the volume limiter 76. A restrictor 76 (commercially available as model 58.6271.1 manufactured by Neoperl, Inc.) limits the amount of water that can pass through the guard bed 66 over a wide pressure range. By knowing the output of the pump 54 and the operating conditions of the electrochemical cell 14, the restrictor 76 maintains the amount of water flowing through the guard bed 66 at a level that maintains an adequate flow rate of water to the electrochemical cell 14. The preferred size can be as follows. Water returns from guard bed 66 to inlet 79 and back to manifold 78 via conduit 77.

  As described above, the electrochemical cell 14 decomposes water into hydrogen gas and oxygen gas, and the oxygen-water mixture returns to the phase separator 40 via the conduit 80. Return manifold 78 receives conduit 80 through inlet 82. The oxygen-water mixture moves along the return manifold 78 and moves to the phase separator body 46. As the mixture enters the body 46, it strikes the inner walls and surfaces, separating water from the gas under the influence of gravity and surface tension and collecting it at the bottom of the separator body 46. The liberated gas exits the separator body 46 via a conduit 84 and is discharged to the cabinet 32 through an outlet 86. The gas exiting the outlet 86 is monitored by the combustible gas sensor 88 to warn if any combustible gas exceeds a predetermined level. The separated water in the body 46 is reused in the system 12 as described above.

  When the electrochemical cell 14 decomposes water, hydrogen gas mixed with water is processed by the HGMS 18. As best shown in FIG. 3, HGMS 18 receives water via manifold 90. The hydrogen aqueous phase separator 92 separates substantially all hydrogen gas from liquid water. Hydrogen gas exits separator 92 via conduit 94, while water collects at the bottom of separator 92. The back pressure regulator 154 described herein ensures that the hydrogen gas pressure is minimized in order to deliver the generated hydrogen gas and return water from the phase separator 92. By pressurizing a small amount of hydrogen gas, the gas is decomposed in water. In the preferred embodiment, the water with cracked hydrogen exits through valve 152 and is depressurized, and the resulting mixture flows through conduit 96 back to oxygen-water phase separator 46. In an alternative embodiment, water with cracked hydrogen exits through valve 152 and conduit 96 and is depressurized and enters hydrogen-water phase separator 150. In this alternative embodiment, the resulting hydrogen gas is vented into the cabinet 38 and the water returns to the oxygen-water phase separator 46 via conduit 151. Hydrogen gas travels through conduit 94 to dryers 98, 99, which are further dried to a desired level, typically 10 parts per million or less per volume at standard temperature and pressure. The dryers 98 and 99 are connected by a manifold 120, and the hydrogen gas is switched between the two dryers 98 and 99 at a predetermined time interval. These dryers, commonly referred to as pressure swings, or swing bed dryers, regenerate a bed with a small slip stream of decompressed dry gas processed by an alternative dryer. The hydrogen gas dryers 98 and 99 are left as they are, and the pressure of the hydrogen gas is measured by the pressure sensor 155. The pressure sensor 155 provides feedback to the control panel 28 to determine a suitable amount of power to provide to the electrochemical cell 14. The amount of power provided by the control panel 28 determines the production rate of the electrochemical cell that results in the output pressure of hydrogen gas. By placing the pressure sensor 155 upstream of the pressure regulator 154, the control panel 28 results from the circulation of the gas dryers 98, 99, as a result of changes in the drain cycle of the phase separator 92, and customer requirements. Pressure fluctuation can be compensated. By adjusting the pressure measured by the pressure sensor 155 slightly above the set pressure of the pressure regulator 154, the system 12 outputs hydrogen to the end user without using the previously required hydrogen buffer tank. The gas pressure can be maintained within +/− 0.5 bar. Typically, the control panel 28 operates to control the pressure of the pressure sensor 155 at a pressure that is 0.1 to 3 bar greater than the set point of the pressure regulator 154. Hydrogen gas exits the system 12 through the outlet 20 for end user use.

  As described above, the system 12 also includes a ventilation system 22 that provides fresh air inside the gas generating compartment 38. A fan 124 in the vicinity of the heat dissipation grill 122 draws outside air. Air travels down the duct 126 and enters the interior of the gas generating compartment 38 near the electrochemical cell 14. In order to exit the compartment 38, air must traverse the conversion 38 vertically and exit through the heat dissipating grill 128. Due to the air flow, the oxygen released by the oxygen-water phase separator vent 86 is quickly removed from the system 12. Any hydrogen exiting, such as hydrogen vented from phase separator 150, is released into the air flow, diluted, and quickly removed from system 12. Sensor 160 detects a loss of ventilation and automatically shuts down system 12 to stop oxygen and hydrogen production. Further, a combustible gas sensor 130 is disposed in the vicinity of the outlet grill 128. When the level of combustible gas in the ventilated air stream approaches an unacceptable level, the system 12 automatically shuts down for maintenance or repair.

  Combustible gas sensors, such as sensors 130 and 88, typically use a technique called “catalytic reaction bead” type sensor (commercially available under the trade name FP-524C by Detcon Inc.). These sensors monitor the percentage of the lower flammable limit (LFL) of the combustible gas in the generated gas stream. This LFL measurement represents a percentage of a given volume in air of a combustible gas such as hydrogen, propane, natural gas (eg, the LFL of hydrogen in air is 4% per volume). These sensors 88, 130 require periodic calibration to ensure proper performance. The calibration process usually requires the user to use a bottle of pre-mixed calibration gas produced at a predetermined mixing ratio of hydrogen and air. This mixture is usually 25-50% of the lower combustion limit of the combustible gas. In the preferred embodiment of the present invention, the system 12 performs automatic calibration of the sensor on a regular basis or facilitates automatic calibration by eliminating the need for user access to the gas generating compartment. Configured for either. The preferred embodiment autocalibration system 30 includes a premixed calibration gas bottle 132, a solenoid valve block 134, an external port 136, and conduits 138, 140, 142, 143.

  In operation, the combustible gas calibration system 30 is triggered when the user is started at predetermined intervals via the interface panel 28 or by the control panel 26. If start-up is triggered by the interface panel, the user has the choice of either automatically connecting an external calibration bottle to port 136 or using internal calibration gas 132. If the user chooses to use an external bottle, the user instructs the interface panel 28 to connect to that bottle. If the user chooses to use the internal calibration gas, the control panel 26 opens the solenoid valve 144 of the valve block 134 to introduce the combustible gas mixture into the conduits 138, 140. The orifices 145, 146 of the conduits 138 and 140 are each sized to allow an appropriate amount of gas to be introduced into the conduit. The gas travels along the conduits 138, 140 to the combustible gas sensors 88, 130. The control panel 26 monitors the level of combustible gas measured by the sensors 88, 130. If the measured level is not the same as the premixed calibration gas level, the control panel adjusts the combustible gas sensors 88, 130 until the appropriate level is reached.

  If calibration is triggered by the expiration of a predetermined time limit, the sequence works and performs substantially the same operation as described above. If the calibration setting deviates from the adjustment by a predetermined amount, the control panel additionally issues a signal to warn the user and / or advise the user and / or shorten the period between calibrations.

  In the event of abnormal operating conditions or parameters, such as a combustible gas sensor calibration being detected, the system 12 includes a number of health monitoring processes that can take corrective action to automatically adjust the operation of the system 12. It is out. In the preferred embodiment of the system 12, the electrochemical cell 14 or a plurality of components such as a power supply are modularly adjusted. This modularity provides further benefits when a fatal error occurs in one module. As will be described in more detail herein, if a fatal error occurs, the system 12 can accept the error and put the system in a mode that slowed the system until repair or maintenance can be performed. This allows the end user to continue to operate without damaging the process.

  In order to perform the functions and desired processing described above, and computer processing therefor (i.e., control algorithms for hydrogen generation, etc.), the control panel 26 and power source 24 include, but are not limited to, a processor, A computer, memory, storage, register, timing, interrupt, communication interface, input / output signal interface, and the like, and combinations comprising at least one of these may be provided. For example, the control panel 26 includes input signal processing and filtering that allows accurate sampling and changes or transitions of these signals from the communication interface. Further features of the control panel 26 and certain processes, functions, and operations are generally discussed in the following respects.

  During the normal operation mode, power is supplied from the power supply 24 to the control panel 26 and the electrochemical cell 14 to generate hydrogen gas as described above. In addition to the processing functions described above, the control panel 26 includes, but is not limited to, circuit breakers, relays, contactors, fuses, dc-dc power regulators, and / or the like. It may have power distribution parts such as a combination. These power distribution components provide power to components in the system 12 such as pumps, fans, solenoid valves and the like. In the normal mode, the current to the electrochemical cell 14 changes to provide the preferred level of hydrogen gas generation that the user needs.

  Referring to FIG. 7, a state change diagram illustrating an exemplary method of control process 200 for system 12 is provided. The process 200 includes several modes and criteria, conditions, events, etc. that control the change of state between the various modes. Process 200 typically operates in normal mode 210 and monitors and evaluates various sensors and conditions to verify the state of system 12. Such monitoring assesses the combustion gas level in the ventilation stream from sensors 88, 130. If the percentage of the lower combustion limit (hereinafter “LFL”) tends to rise above the time and level where the LFL remains below the threshold, the process 200 moves to log mode 212 to record LFL data, A warning is sent to the user interface 28.

  When the process 200 detects that the LFL has exceeded a predetermined threshold, which is an indication that a repair or preventive action is required, the process transitions to a diagnostic mode 214 to evaluate the electrochemical cell 14. In order to determine whether the high LFL reading is due to failure or wear of the electrochemical cell 14, each electrochemical cell 14 is operated individually in diagnostic mode 214 to obtain the LFL reading from the sensors 88, 130. To monitor. If the LFL measurement is greater than the shutdown level, or if the LFL measurement does not drop, or if only one electrochemical cell 14 is operating, the process 200 transitions to the shutdown mode 216 and the system 12 processes. In a sequential manner. Process 200 notifies the user using alert mode 218.

  If diagnostic mode 214 determines which electrochemical cell 14 is responding to a high LFL level, process 200 transitions to reduced mode 220. Reduced mode 220 turns off the appropriate module of power supply 24 and turns off the electrochemical cell 14 that is not operating due to failure. In the log mode 212, appropriate data is recorded and the user is warned. When system 12 shuts down and operates correctly, process 200 is reset to normal mode 210.

  Another error condition performed by the system 12 is an excess water temperature in the manifold 58. Temperature measurements are obtained from sensor 70 during normal operating mode 210 and are monitored and analyzed by process 200. If the normal mode 210 detects that the temperature is rising and the actual water temperature is below the predetermined threshold, the process 200 moves to the log mode 212 to record this information and prompt the user. Send a warning.

  If the water temperature measured by sensor 70 exceeds a predetermined threshold, process 200 transitions to reduction mode 222. In the reduction mode 222, the current output of the power supply 24 is reduced, and the hydrogen gas output of the electrochemical cell 14 is reduced. Process 200 transitions to log mode 212 to record temperature information and alert the user that the capacity of system 12 has been reduced. When system 12 shuts down and operates correctly, process 200 is reset to normal mode 210. If the temperature measured by sensor 70 is maintained above a second predetermined threshold that is typically equal to the maximum operating temperature of guard bed 66, process 200 transitions to shutdown mode 216 to process system 12. Stop in sequential manner. Process 200 alerts the user using alert mode 218.

  Another error condition that the system 12 may experience is a low voltage or high voltage condition within the electrochemical cell 14. When the normal mode 210 detects a voltage rising or falling trend, the process 200 moves to the log mode 212 to record information and send a warning to the user. If the voltage required to operate the electrochemical cell 14 falls below the threshold, rises above the threshold, and there is current being delivered by the electrochemical cell 14, the process 200 is in diagnostic mode. Moving to 228, it is determined which electrochemical cell is operating at other than normal parameters. If only one electrochemical cell 14 is operating, the process 200 transitions to the shutdown mode 216 and stops the processing of the system 12 in a sequential manner. Process 200 notifies the user using alert mode 218.

  If more than one electrochemical cell 14 can be operated, the process 200 transitions to a reduced mode 226 to turn off the power providing power to the failed electrochemical cell and the system in the remaining electrochemical cell. 12 will continue to operate. Reduce mode 226 continues to monitor and analyze the voltage of the electrochemical cell, and if an upward or downward trend is detected, as in the above operation, process 200 transitions to log mode 212 to record information. , Send a warning to the user. When system 12 shuts down and operates correctly, process 200 is reset to normal mode 210. If the voltage again rises above the predetermined threshold or falls below the predetermined threshold, the process 200 again enters diagnostic mode 228 and repeats the above sequence again. This process continues until the system 12 is repaired or reset or it is determined that the last electrochemical cell has failed.

  Another error encountered by the system 12 is a failed power supply module in the power supply 24. When process 200 in normal mode 210 detects a power failure, process 200 transitions to diagnostic mode 230. The diagnostic mode 230 interacts with each module in the power supply 24 to determine which individual module has failed. If the diagnostic mode 230 determines which module has failed, the process 200 transitions to a reduced mode 232 to disconnect the failed power supply module and continue operation. If multiple power supply modules are required to operate a single electrochemical cell 14, reduction mode 232 disconnects all power supply modules associated with the failed module. The process 200 also transitions to a log mode, records appropriate power information, and sends a warning to the user. Process 200 then continues operation of system 12 in a reduced mode. The process 200 is reset to the normal mode 210 when the system 12 shuts down and operates correctly. If the other power fails, the sequence when process 200 transitions to diagnostic mode 230 is repeated. If there are not enough power modules to operate a single electrochemical cell 14, process 200 transitions to shutdown mode 216 to stop the processing of system 12 in a sequential manner. Process 200 notifies the user using alert mode 218.

  The last example of an error that the system 12 may encounter is a low flow rate of deionized water at the inlet. In order to maintain the operation of the system 12, it is usually necessary to provide a constant supply of fresh deionized water. If the flow rate of this deionized water is reduced or stopped due to the problem of the external water source 17 and sufficient deionized water is not supplied to the electrochemical cell 14, the system may be damaged. . The flow rate of water from the deionizer 17 is determined by measuring the amount of time required to change the water level measured by the sensor 48 in the oxygen-water phase separator 46. If the normal mode 210 determines that the inlet deionized water flow rate is too low, the process 200 can move to a diagnostic mode 234 to achieve what hydrogen gas production rate at the available deionized water inlet flow rate. To decide. Process 200 transitions to reduction mode 236 to reduce the current from power supply 24 and reduce the hydrogen generation rate of electrochemical cell 14. Reduce mode 236 monitors the flow rate at the inlet of deionized water in the manner described above and continues the analysis. The process 200 is reset to the normal mode 210 when the system 12 shuts down and is operating properly or when the deionized water flow returns to normal operating conditions. If the water flow rate tends to decrease, the process 200 transitions to the log mode 212 to record the information and send a warning to the user.

  If the inlet water flow rate has dropped below the second threshold, the process 200 returns to diagnostic mode 234 and repeats the sequence until the inlet flow rate is reduced to a minimum operating level, as described above. When the minimum operating level is reached, process 200 transitions to shutdown mode 216 and stops the processes of system 12 in a sequential manner. Process 200 notifies the user using alert mode 218.

  While the preferred embodiment has been shown and described, various modifications and changes can be made without departing from the spirit and scope of the invention. For example, the example shown here specifically refers to an electrochemical system having three electrochemical cells, but can be applied to systems having two, four or more electrochemical cells as well. it can. Accordingly, the invention is illustrated by the drawings but is not limited thereto.

Reference is made to the drawings, which are exemplary and not limiting. Here, the same symbols are assigned to the same elements.
FIG. 1 is a schematic view of a portion of a conventional electrochemical cell showing an electrochemical reaction. FIG. 2 is a perspective view of an exemplary embodiment of a hydrogen generation system. FIG. 3 is a diagram illustrating piping and instruments of the hydrogen generation system of FIG. FIG. 4 is a perspective view of the water management system of FIG. FIG. 5 is a perspective view showing the oxygen-water phase separator and water management manifold of FIG. FIG. 6 is a plan view showing the water deionization filter and the water restrictor of FIG. FIG. 7 is a state change diagram showing an exemplary embodiment of the control system in the operation degradation mode due to the excessive LEL level. FIG. 8 is a state change diagram showing an exemplary embodiment of the control system in the operation lowering mode caused by high-temperature water. FIG. 9 is a state change diagram illustrating an exemplary embodiment of a control system in a reduced operation mode caused by a high voltage or a low voltage of an electrochemical cell. FIG. 10 is a state change diagram illustrating an exemplary embodiment of the control system in the operation deterioration mode caused by a power failure. FIG. 11 is a state change diagram showing an exemplary embodiment of the control system in the operation reduction mode due to the low flow rate of deionized water at the inlet.

Claims (21)

In electrochemical systems:
A plurality of individual electrochemical cell stacks;
A water-oxygen management system in fluid communication with the plurality of electrochemical cell stacks;
A hydrogen management system in fluid communication with the plurality of electrochemical cell stacks;
An electrochemical system characterized by comprising: 2. The electrochemical system according to claim 1, further comprising a control system for monitoring and operating the electrochemical system, the control system further comprising means for detecting an abnormal operating state. The electrochemical system of claim 2, wherein the control system further comprises means for reducing the performance of the electrochemical system in response to the abnormal condition. The electrochemical system according to claim 3, further comprising ventilation means for the system. In electrochemical systems:
A plurality of individual electrochemical cell stacks;
An oxygen-water phase separator in fluid communication with the plurality of electrochemical cell stacks, wherein the first manifold discharges water into the electrochemical cell stack, and the second manifold receives water from the electrochemical cell stack. A separator comprising a plurality of cell stack outlets, wherein the first manifold discharges water to the electrochemical cell and a guard bed outlet;
An electrochemical system characterized by comprising: 6. The electrochemical system of claim 5 further comprising a discharge conduit that is in fluid communication with the phase separator, the conduit receiving a gas flow from the phase separator, and an exhaust for discharging the gas flow. An electrochemical system comprising a port. The electrochemical system of claim 6, further comprising a flow reducer coupled to the first manifold guard bed outlet, wherein the flow reducer limits the amount of water beyond a pressure range from the guard bed outlet. An electrochemical system characterized by that. In a system that automatically calibrates combustible gas sensors:
A user interface;
A control panel connected to the user interface;
A premixed combustible gas canister;
At least one combustible gas sensor electrically connected to the control panel;
A system characterized by comprising. 9. The system for automatically calibrating a combustible gas sensor according to claim 8, further comprising a valve structure in fluid communication with the canister and the at least one combustible gas sensor. 10. The system for automatically calibrating a combustible gas sensor according to claim 9, wherein the valve structure is electrically connected to the control panel. In a method of automatically calibrating a combustible gas sensor:
Releasing a premixed combustible gas at a predetermined interval;
Injecting the premixed combustible gas into the detection surface of the combustible gas sensor;
Measuring the level of combustible gas detected by the sensor;
A method characterized by comprising. 12. The method of automatically calibrating a combustible gas sensor according to claim 11, further comprising automatically adjusting calibration of the sensor in response to the measurement. In a system for controlling the output pressure of an electrochemical system, the system includes:
At least one electrochemical cell;
A pressure regulator having a set point, wherein the pressure regulator is in fluid communication with the electrochemical cell;
A pressure sensor in fluid communication with the pressure regulator between the pressure regulator and the electrochemical cell;
Means for controlling the output of the electrochemical cell in response to the pressure sensor, and means for maintaining the pressure of the pressure sensor at a predetermined pressure equal to or higher than a set point of the pressure regulator;
A system characterized by comprising. 14. The system for controlling the output pressure of an electrochemical system according to claim 13, wherein the means for controlling the output comprises a control panel for monitoring the pressure sensor. In a method for controlling an electrochemical cell system:
Operating a plurality of electrochemical cells;
Supplying power from a plurality of power sources electrically connected to the plurality of electrochemical cells;
Monitoring the operation of the plurality of electrochemical cells and the plurality of power sources with a control system;
Detecting an error condition;
Accepting the detected error condition and adjusting the operation of the control system;
A method characterized by comprising. 16. The method of controlling an electrochemical cell system according to claim 15, wherein the error condition is a power failure and the adjusting operation comprises reducing the output of one of the plurality of electrochemical cells. Feature method. 16. The method of controlling an electrochemical cell system according to claim 15, wherein the error condition is a high LFL measurement and the adjusting action determines which electrochemical cell is generating a high LFL level. A method characterized by comprising. 18. The method of controlling an electrochemical cell system according to claim 17, wherein the method of determining which electrochemical cell is generating a high LFL level is one of the plurality of electrochemical cells. A method comprising providing power to an electrochemical cell. The method of controlling an electrochemical cell system according to claim 18, further comprising the step of measuring an LFL level of a gas generated by the single electrochemical cell. 16. The method of controlling an electrochemical cell system according to claim 15, wherein the error condition is excessive water temperature, and the adjusting operation comprises reducing the output of the plurality of power sources. . 16. The method of controlling an electrochemical cell system according to claim 15, wherein the error condition is a failure of one of the plurality of power supplies, and the adjustment operation determines which single power supply is faulty. And a step of disconnecting the power source.

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