Electrolyzer system

Abstract

Electrolyzer system (2), in particular a proton exchange membrane electrolyzer system, comprising - an electrolysis unit (4) for the electrolytic production of gaseous hydrogen (16) from liquid process water (12) by means of a cathode (8) and an anode (10), - an anode-side system (20) with a water supply (24) connected to the electrolysis unit (4) on the anode side for supplying process water (12) to the electrolysis unit (4), - a cathode-side system (22) with a hydrogen removal system (84) connected to the electrolysis unit (4) on the cathode side for removing the generated hydrogen (16) from the electrolysis unit (4), and - a controller (114) for central plant control, which controls and / or regulates the anode-side plant system (20) and the cathode-side plant system (22).

Description

[0001] The invention relates to an electrolyzer system, in particular a proton exchange membrane electrolyzer system, comprising an electrolysis unit for the electrolytic production of gaseous hydrogen from liquid process water by means of a cathode and an anode.

[0002] Hydrogen is used in the chemical industry as synthesis gas and as an energy carrier for fuel cells. Electrolyzer plants are used for the industrial production of hydrogen, splitting liquid water into oxygen and hydrogen through electrolysis.

[0003] The core component of such an electrolyzer system is an electrolysis unit, in which water is electrolytically split between two electrodes using direct current. The water is reduced to hydrogen at a cathode and oxidized to oxygen at an anode.

[0004] To avoid mixing the gases produced, the anode side and the cathode side of the electrolysis unit are typically separated by a membrane or a porous separator that is permeable to ionic charge carriers.

[0005] In a proton exchange membrane (PEM) electrolyzer, the electrodes are separated from each other by a PEM membrane, which is typically a proton-permeable polymer membrane. The PEM separates the anode from the cathode and allows the selective passage of protons from the anode to the cathode, while separating the gases (hydrogen and oxygen) and preventing them from mixing.

[0006] Water is supplied to the anode, where it is split into protons, electrons, and oxygen. At the cathode, the protons that have diffused through the PEM combine with electrons to form hydrogen gas.

[0007] For reliable and safe operation of the electrolyzer system, it is necessary to monitor and control the various parameters of the electrolysis process, such as temperature, pressure, water supply, and gas discharge. Furthermore, both the oxygen and hydrogen gases must be handled carefully, requiring components for gas purification, drying, and pressure regulation. For this purpose, the electrolysis unit is coupled with an anode-side system (oxygen side) and a cathode-side system (hydrogen side).

[0008] The anode-side system includes a water supply to continuously provide the anode with water. The water is pumped into the electrolysis unit and, if necessary, filtered and degassed to remove impurities that could interfere with the electrolysis process. The anode-side system also features oxygen removal to extract the oxygen produced during electrolysis. Typically, some of the water carries the oxygen along with it, necessitating gas-liquid separation to separate the oxygen from the water. Heat is generated during the electrolysis process. Therefore, cooling of the anode-side system is required to regulate the temperature and maximize the efficiency of the electrolysis process.

[0009] The cathode-side system includes a hydrogen removal unit to discharge the generated gaseous hydrogen from the cathode. Since the hydrogen gas is also saturated with moisture, a gas-liquid separation is performed to separate the hydrogen from water droplets. Cooling is also necessary on the cathode side to dissipate the heat generated by the electrolysis process.

[0010] Electrolyzer systems are therefore highly complex, and their operation is controlled by electronic control units. Traditionally, the individual system components (water supply, oxygen removal, hydrogen removal, cooling, etc.) are each regulated and monitored by a dedicated control unit. These control units are typically implemented as programmable logic controllers (PLCs).

[0011] Therefore, controlling an electrolyzer system requires a large number of control units, which must be interconnected both with their respective system components and with each other via signal connections. The resulting complex wiring is time-consuming and incurs additional costs during the setup and commissioning of such an electrolyzer system.

[0012] The invention is based on the objective of providing a particularly suitable electrolyzer system. In particular, the wiring effort required for setting up and commissioning the electrolyzer system should be reduced.

[0013] The problem is solved according to the invention with the features of claim 1. Advantageous embodiments and further developments are the subject of the dependent claims.

[0014] The electrolyzer system according to the invention comprises an electrolysis unit for the electrolytic production of gaseous hydrogen from liquid process water by means of a cathode and an anode.

[0015] In this and the following, "process water" refers specifically to highly purified water that is demineralized or completely desalinated and has a particularly low electrical conductivity, for example, less than 0.1 µS / cm (microsiemens per cm). For example, ultrapure water is used that has been treated by reverse osmosis, ion exchange, or distillation.

[0016] The anode, for example, is made of a precious metal catalyst such as iridium oxide to support the oxidation reaction. The cathode, for example, is made of a catalyst such as platinum to promote the reduction reaction.

[0017] The electrolysis unit is specifically designed as a proton exchange membrane (PEM) electrolysis unit, in which the cathode and anode are separated by a proton exchange membrane (PEM). To optimize throughput, the cathode and anode are specifically designed as multilayer electrode stacks, also known as PEM stacks.

[0018] The electrolyzer system has an anode-side system and a cathode-side system.

[0019] The anode-side system forms the oxygen side of the electrolyzer and includes a water supply connected to the electrolysis unit for feeding process water into the unit. Specifically, the water supply for feeding the process water is designed as a water circuit that includes the electrolysis unit and its anode as a section of the circuit. The oxygen generated at the anode is carried away via the water circuit and extracted from the process water at a suitable point within the circuit. The oxygen is then either discharged or, in some applications, collected and used.

[0020] The cathode-side system forms the hydrogen side of the electrolyzer plant and features a hydrogen removal system connected to the electrolysis unit on the cathode side for the discharge of the hydrogen produced by the electrolysis unit. Specifically, the hydrogen removal is carried out via a backpressure valve, which is suitable for introducing the gaseous hydrogen into a downstream piping system and / or a storage device.

[0021] The conjunction “and / or” is to be understood here and in the following as meaning that the features linked by means of this conjunction can be both common and alternative to each other.

[0022] According to the invention, the electrolyzer system comprises a controller (i.e., a control unit) for central system control, which controls and / or regulates the anode-side and cathode-side system components. The controller is thus designed as a central control unit for the electrolyzer system, eliminating the need for individual system controllers, such as PLC controllers. The central controller essentially limits the number of control units required for operating the electrolyzer system to one (1), thereby advantageously reducing the wiring complexity and costs during the setup and commissioning of the electrolyzer system according to the invention.

[0023] The invention is based on the understanding that such electrolyzer systems are becoming increasingly standardized and established. The controller according to the invention is designed as a control unit specifically developed for such electrolyzer systems, comparable to an engine control unit for an internal combustion engine in the automotive sector.

[0024] The controller is generally designed – programmatically and / or circuit-wise – for controlling and / or regulating the electrolyzer system. In a preferred embodiment, the controller is at least essentially a microcontroller with a processor and a data memory, in which the system control functionality is implemented programmatically as operating software (firmware), so that the process – optionally in interaction with a user – is carried out automatically when the operating software is executed in the microcontroller. Alternatively, within the scope of the invention, the controller can also be a non-programmable electronic component, such as an application-specific integrated circuit (ASIC) or an FPGA (field-programmable gate array), in which the system control functionality is implemented using circuitry.

[0025] In an advantageous further development, the anode-side system and the cathode-side system each have an associated control loop. The control loop of the anode-side system is hereinafter also referred to as the anode control loop, and the control loop of the cathode-side system is accordingly also referred to as the cathode control loop. The anode control loop is suitable and configured to control and / or regulate the water supply to the electrolysis unit. The cathode control loop is accordingly suitable and configured to control and / or regulate the hydrogen removal.

[0026] The anode control loop and the cathode control loop each have a controller integrated into the controller and at least one peripheral or field device that is directly connected to the controller via signal transmission. The peripherals for control and / or regulation are thus centrally connected to the controller via signal transmission. The connection between the controller and the at least one peripheral device is established, for example, via wired signal lines or a wireless communication link (e.g., WiFi, Bluetooth, RFID, etc.).

[0027] In this and the following, a "peripheral device" refers specifically to a device that operates in conjunction with the central controller but is located outside of it. A peripheral device serves to input or output data, signals, or power, or to monitor and control processes. For example, a peripheral device is a measuring element (sensor) for acquiring information or an actuator for executing an action based on such information.

[0028] In a preferred embodiment, the controller features control functions and condition monitoring for controlling and / or regulating the anode-side and cathode-side systems, which are implemented in the controller's software. This allows control parameters for the anode and / or cathode control loop to be easily and individually adapted for each electrolyzer system, ensuring particularly efficient and reliable operation. Furthermore, the electrolyzer system can always be expanded or modified beyond its existing functionality through appropriate software programming of the controller. In particular, the controller thus implements a "plug and play" (PnP) approach for the electrolyzer system, allowing, for example, additional peripheral devices to be connected to the controller and immediately ready for operation.

[0029] In one possible configuration, the water supply system includes a water reservoir connected to a fresh water supply. The fresh water supply is designed and configured to supply new process water—that is, process water that has not yet passed through the electrolysis unit (fresh water)—to the water reservoir.

[0030] The anode control loop regulates and / or controls the supply of new process water from the fresh water supply into the water reservoir, depending on its fill level. This ensures that the electrolysis unit is continuously supplied with sufficient process water required for the electrolysis process. The new process water supplied via the fresh water supply is, for example, demineralized or desalinated by a water treatment system.

[0031] The water reservoir includes, for example, a water tank (water container) for the process water. The water tank is made of a corrosion-resistant material such as stainless steel or plastic and is designed to protect the process water from contamination and external influences.

[0032] The water reservoir is an integral part of the water supply system's water cycle. New process water from the fresh water supply and used process water from the electrolysis unit are fed into the reservoir, while process water is discharged towards the electrolysis unit. The reservoir incorporates, for example, a degassing system to remove dissolved oxygen gas from the used process water, ensuring that only clean process water is conveyed to the electrolysis unit.

[0033] The fresh water supply system has a supply line for adding new process water and a discharge line for removing process water from the water circuit. Both the supply and discharge lines are connected to the water reservoir, which thus also acts as a buffer for the water circuit.

[0034] The anode control loop includes a controllable (supply / discharge) valve for the fresh water supply and a level sensor for the water reservoir as peripheral devices, which are directly connected to the controller. Specifically, the anode control loop has a dedicated valve for each of the supply and discharge lines. The quantity or volume of fresh process water supplied (supply line) and discharged (discharge line) can be controlled via these supply and discharge valves. The level sensor is a sensor or measuring device that detects the fill level of the process water in the water reservoir.

[0035] The anode control loop incorporates a level control system that regulates the water level within the reservoir to a desired setpoint. If the level falls below the setpoint, fresh process water is added; if the level rises above the setpoint, process water is removed from the reservoir.

[0036] In an advantageous further development, the water supply includes a heat exchanger for temperature control of the process water supplied to the electrolysis unit. The heat exchanger is connected to a separate coolant circuit, and the anode control loop monitors and / or regulates the temperature of the process water. The heat exchanger ensures that the process water supplied to the electrolysis unit has the desired process temperature for the electrolysis process, thereby improving electrolysis efficiency.

[0037] The heat exchanger is specifically coupled to the water supply circuit. During the electrolysis process, heat is generated, which warms the process water circulating in the water circuit. The heat exchanger is designed and configured to cool the process water and thus regulate its temperature.

[0038] In a suitable configuration, the anode control loop controls and / or regulates the temperature of the process water by means of a coolant flow rate in the coolant circuit. The anode control loop thus provides temperature control.

[0039] For this purpose, a temperature sensor at the inlet of the electrolysis unit and a controllable coolant valve in the coolant circuit are connected to the controller as peripheral devices. The temperature sensor measures the temperature of the process water flowing into the electrolysis unit, while the coolant valve controls the coolant flow rate in the coolant circuit—and thus the cooling capacity of the heat exchanger. For example, if the incoming process water temperature is too high, the coolant valve opens further to increase the coolant flow rate and thus the cooling capacity.

[0040] An additional or further aspect of the invention provides that the anode circuit controls and / or regulates the temperature of the process water by supplying new process or fresh water from the fresh water supply into the water reservoir.

[0041] As explained above, the process water in the water supply's water circuit heats up due to the electrolysis process. The fresh water supply is not part of this water circuit, so the fresh water in the fresh water supply has a substantially constant temperature level upon entry. For example, the fresh water is at room temperature. Alternatively, the fresh water supply may have a temperature control unit to bring the fresh water to a desired temperature upon entry. The fresh water therefore typically has a different temperature than the process water circulating in the water circuit; in particular, the fresh water is preferably cooler than the process water. This temperature difference is used by the anode control loop or temperature control system to control and / or regulate the process water temperature.

[0042] If the process water temperature is above a setpoint temperature, the temperature control system activates the supply and discharge valves of the fresh water supply to introduce cool fresh water into the water reservoir and to discharge warm process water, thereby cooling the water temperature in the water circuit.

[0043] In a practical implementation, the supply of new process water from the fresh water supply into the water reservoir is controlled by a feedforward control system of the controller. This eliminates the need for a temperature sensor for the water temperature within the reservoir. By introducing cooler fresh water into the water circuit, the fresh water supply is thus actively incorporated as a disturbance variable into the temperature control of the process water supplied to the electrolysis unit.

[0044] In a preferred further development, the anode control loop controls and / or regulates the flow rate of the process water supplied to the electrolysis unit. The anode control loop thus features flow rate control for the water circuit or the water supply to the electrolysis unit. This ensures that the electrolysis unit, and in particular the anode, is continuously supplied with sufficient process water, enabling reliable and safe electrolysis.

[0045] In a practical design, the anode control loop includes a flow sensor for detecting the volume flow of the process water supplied to the electrolysis unit and a limiting valve for adjusting this volume flow as peripheral devices, which are directly connected to the controller via signal transmission.

[0046] In one possible configuration, the limiting valve is connected in parallel to the electrolysis unit, particularly as a bypass valve. This prevents pressure spikes in the water circuit's piping system. Furthermore, it allows process water to circulate within the water circuit, bypassing the electrolysis unit, and thus, for example, to be cooled further before being fed to the electrolysis unit.

[0047] For more precise control and / or regulation of the volume flow of the process water supplied to the electrolysis unit, a special embodiment has a first limiting valve as a bypass valve of the electrolysis unit and a second limiting valve at the inlet of the electrolysis unit, each of which is directly connected to the controller via signal transmission as a peripheral device.

[0048] To pump and circulate the process water within the water circuit, the water supply preferably includes a pump unit, for example, a circulation pump. In an alternative configuration, the anode control loop directly controls and / or regulates the flow rate of the process water supplied to the electrolysis unit by means of the pump unit, based on a pressure differential on the anode side of the electrolysis unit. In other words, the pump unit is controlled and / or regulated depending on the anode pressure. In this configuration, limiting or bypass valves for regulating the flow rate of the water circuit can therefore be omitted, since the flow rate is directly regulated and / or controlled by the pump operation.

[0049] The anode control loop includes the pump unit and, for example, a differential pressure sensor as peripheral devices connected to the controller. The differential pressure sensor is connected between the inlet and outlet of the anode side. Alternatively, two pressure sensors, one at the inlet and one at the outlet, are used, with the pressure difference being determined from the measured pressure values.

[0050] By controlling and / or regulating the flow rate depending on the anode pressure or the pressure differential on the anode side, it is ensured that, on the one hand, there is always a sufficient supply of process water for electrolysis, and on the other hand, that no excessive mechanical stresses are exerted on the PEM. This advantageously increases the service life of the electrolysis system.

[0051] The hydrogen produced at the cathode is often saturated with water droplets. In a further advantageous design, the hydrogen removal system therefore includes a water separator to separate liquid process water from the generated gaseous hydrogen. The water separator is essentially located directly after the cathode of the electrolysis unit, so that the hydrogen is dehumidified before being fed into other processes or stored. The water separator uses, for example, mechanical means such as cyclone separators, baffle plates, or filter elements to separate the process water from the hydrogen gas. The separated process water collects in a holding tank within the water separator, while the dehydrated gas is passed on. The collected process water is then discharged and, if necessary, fed into the fresh water supply after appropriate water treatment.

[0052] The cathode control loop is designed and configured for controlling and / or regulating the cathode pressure in the water separator. For this purpose, the water separator has a pressure sensor, which is directly connected to the controller via a signal path and measures the cathode pressure. "Cathode pressure" here refers to the pressure of the hydrogen gas on the cathode side of the electrolysis unit. Controlling and / or regulating the cathode pressure is important to ensure the most efficient electrolysis process in the electrolysis unit and to prevent damage to or leaks in the cathode-side system.

[0053] The cathode pressure is controlled and / or regulated, particularly in conjunction with the anode pressure, since the pressure ratio between these two sides of the membrane influences the performance and safety of the entire electrolysis plant.

[0054] Preferably, the hydrogen removal system includes gas conditioning systems downstream of the water separator to improve the quality and purity of the hydrogen gas. For example, a heat exchanger with a separate coolant circuit and a condensate drain are provided. This cools the hydrogen gas and removes any condensate that forms.

[0055] In one possible configuration, the cathode control loop controls and / or regulates the cathode pressure via a backpressure valve connected to the water separator. For this purpose, the water separator is equipped with a pressure sensor. The pressure sensor and the backpressure valve are directly connected to the controller via signal transmission as peripheral devices. By adjusting the backpressure level, simple and reliable control and / or regulation of the cathode pressure is thus enabled.

[0056] Additionally or alternatively, the cathode pressure is controlled and / or regulated by the cathode control loop via the power output of the electrolysis unit. For this purpose, the electrical power output of the electrolysis unit is measured. For example, the controller incorporates a current and / or voltage sensor in the DC circuit of the electrolysis unit. The electrical power output of the electrolysis unit correlates with the amount of hydrogen produced, and thus with the cathode pressure. Therefore, the cathode pressure can be adjusted and / or controlled by simple current and / or voltage regulation.

[0057] In a possible further development, the water separator has a level sensor, whereby the cathode control loop controls and / or regulates the fill level in the water separator by means of the cathode pressure. The level sensor detects, for example, the water level of the separated process water in the water separator.

[0058] The invention is explained in more detail below with reference to a drawing. The drawing shows, in schematic and simplified representations: Fig. 1 an electrolyzer system, Fig. 2 an anode control loop of the electrolyzer system for controlling a process water temperature, Fig. 3 an anode control loop of the electrolyzer system for controlling a process water volume flow, Fig. 4 an anode control loop of the electrolyzer system for controlling the process water volume flow in an alternative design, Fig. 5 a cathode control loop of the electrolyzer system for controlling a cathode pressure.

[0059] Corresponding parts and sizes are always marked with the same reference symbols in all figures.

[0060] The Fig. Figure 1 shows a schematic piping and instrumentation diagram of an electrolyzer system 2 comprising an electrolysis unit 4 with an electrolysis chamber 6 as well as with a cathode 8 and with an anode 10.

[0061] The cathode 8 and anode 10 project into the electrolysis chamber 6. Preferably, the cathode 8 and the anode 10 are configured as electrode stacks inside the electrolysis chamber 6. During operation of the electrolysis unit 4, the electrolysis chamber 6 is filled with process water 12, with at least the anode 10 being immersed in the process water 12 of the electrolysis chamber 6. The electrodes 8, 10 are connected to a DC circuit, so that the process water 12 is split into gaseous oxygen 14 and gaseous hydrogen 16 by electrolysis due to the DC voltage.

[0062] In the illustrated embodiment, the electrolysis unit 4 is designed as a proton exchange membrane electrolysis unit, in which the electrolysis chamber 6 is separated into an oxygen or anode side and a hydrogen or cathode side by means of a proton exchange membrane 18. The process water 12 is supplied to the anode 10, which splits it into protons, electrons, and oxygen 14. At the cathode 8, the protons that have diffused through the proton exchange membrane 18 combine with electrons to form the hydrogen gas 16.

[0063] The oxygen side of the electrolysis chamber 6 is connected to an anode-side system 20 and the hydrogen side of the electrolysis chamber 6 is connected to a cathode-side system 22.

[0064] The anode-side system 20 has a water supply 24 coupled to the anode side of the electrolysis chamber 6, by means of which the electrolysis chamber 6 is continuously supplied with process water 12.

[0065] The water supply 24 has a water circuit 26 for the process water 12. The water circuit 26 is connected to the anode side of the electrolysis chamber 6. The electrolysis chamber 6 is connected to the water circuit 26 by means of an inlet and outlet (not specified in detail). During operation, process water 12 flows into the electrolysis chamber 6 through the inlet and out of the electrolysis chamber 6 through the outlet.

[0066] The water circuit 26 further includes a water reservoir 28 as a buffer storage tank for the process water 12. A pump unit 30, acting as a fluid or water pump, is provided for pumping the process water 12 in the water circuit 26. The pump unit 30 is preferably designed as a circulation pump. An adjustable throttle 32, a heat exchanger 34, and an ion exchanger 36 are arranged in series between the pump unit 30 and an anode-side inlet of the electrolysis chamber 6.

[0067] An adjustable limit valve 38 is optionally connected between the ion exchanger 36 and the inlet of the electrolysis chamber 6. The water circuit 26 also has an optional bypass line, which is arranged parallel to the water section of the electrolysis chamber 6 and which has an adjustable limit valve 40 as a bypass valve. The bypass line is located between the ion exchanger 36 and the limit valve 38. The limit valves 38 and 40 are, for example, designed as valves with an actuator.

[0068] The water reservoir 28 has a water tank 42 for the process water 12. The water reservoir 28 also has an optional temperature sensor 44 for measuring the temperature of the process water 12 within the water tank 42. The water reservoir 28 additionally has a level sensor 46 for measuring the fill level or level of the process water 12 within the water tank 42.

[0069] A degassing system is integrated into the water tank 42, by means of which dissolved oxygen 14 is removed from the process water 12 and discharged via an oxygen line. A hydrogen sensor 48 is integrated into the oxygen line, which detects the concentration of hydrogen 16 in the oxygen 14.

[0070] The water reservoir 28 is connected to a fresh water supply 50. The fresh water supply 50 has a supply line (fresh water line) 52 for supplying fresh water, i.e., new process water 12, and a discharge line (waste water line) 54 for discharging waste water, i.e., used process water 12. The supply line 52 has an adjustable supply valve 56, and the discharge line 54 has an adjustable discharge valve 58. The supply valve 56 and the discharge valve 58 are, for example, designed as valves with an integrated position or process controller.

[0071] A pressure sensor 60 for detecting water pressure is coupled to the water circuit 26 between the outlet of the pump unit 30 and the throttle 32. Furthermore, a temperature sensor 62 for detecting water temperature is located between the heat exchanger 34 and the ion exchanger 36, and a conductivity sensor 64 for detecting the electrical conductivity of the process water 12 is located between the ion exchanger 36 and the limit valves 36, 38.

[0072] The heat exchanger 34 is designed and configured for temperature control, and in particular for cooling, the process water 12. For this purpose, the heat exchanger 34 is coupled to a coolant circuit 66. The coolant circuit 66 contains, for example, a water-glycol mixture as the coolant. The coolant circuit 66, shown only in part, includes a throttle 68 connected in parallel to the heat exchanger 34, a temperature sensor 70 for detecting the coolant temperature, and an adjustable coolant valve 72. The heat exchanger 34 and the coolant circuit 66 form a process cooling system for the plant 20.

[0073] The ion exchanger 36, acting as a water treatment unit, ensures that highly purified water is supplied to the electrolysis unit 4 as process water 12. The ion exchanger 36 is designed, for example, as an anion and / or cation exchanger to demineralize the process water 12 and remove impurities.

[0074] On the inlet side of the electrolysis chamber 6, a temperature sensor 74 for detecting the water temperature of the process water 12 introduced into the electrolysis unit 4, a pressure sensor 76 for detecting the water pressure of the introduced process water 12, and a flow sensor 78 for detecting the introduced quantity of process water 12 are arranged. A differential pressure sensor 80 is connected between the inlet and the outlet of the electrolysis chamber 6. A temperature sensor 82 for detecting the water temperature of the process water 12 flowing out of the electrolysis unit 4 is also located at the outlet of the electrolysis chamber 6.

[0075] The cathode-side system 22 has a hydrogen removal 84 for the discharge of the hydrogen 16 produced during electrolysis.

[0076] The hydrogen removal unit 84 includes a water separator 86 and a heat exchanger 88, as well as a condensate drain 90 and a backpressure valve 92. The backpressure valve 92 is, for example, designed as a blow-off valve.

[0077] The plant system 22, or the hydrogen removal unit 84, also features a nitrogen supply 94 for the on-demand supply of gaseous nitrogen 96 as a protective or purge gas (inert gas). The nitrogen supply 94 allows, for example, the cathode side of the electrolysis chamber 6 and / or the piping system of the hydrogen removal unit 84 to be purged with nitrogen 96, thus reliably and safely preventing oxyhydrogen reactions, for example, during maintenance or repair work on the hydrogen removal unit 84.

[0078] A temperature sensor 97 is arranged at the outlet of the cathode side to detect the hydrogen temperature.

[0079] The water separator 86 is connected to the cathode side of the electrolysis chamber 6 and separates the gaseous hydrogen 16 from liquid process water 12, which is carried along, for example, as droplets by the gas stream from the electrolysis chamber 6. The separated process water 12 collects in a collection vessel in the water separator 86, while the dehydrated gas is passed on.

[0080] The collected process water 12 is discharged via a discharge line 98. The discharge line 98 has a discharge valve 100 and an adjustable throttle 102. The discharge valve 100 is, for example, designed as a valve with an integrated positioner or process controller.

[0081] The water separator 86 has two level sensors 104, 106, wherein the level sensor 104 detects a level of the separated process water 12 and the level sensor 106 detects a level of the gaseous hydrogen 16.

[0082] Between the water separator 86 and the heat exchanger 88, a pressure sensor 108 for detecting hydrogen or cathode pressure and a temperature sensor 110 for detecting hydrogen temperature are arranged. Downstream of the backpressure valve 92, a flow sensor 112 for detecting the amount of hydrogen discharged is arranged.

[0083] The heat exchanger 88 is connected to a coolant circuit 113, in which a water-glycol mixture is used as the coolant. The heat exchanger 88, or rather the coolant circuit 113, is designed and configured to cool the hydrogen gas stream 16.

[0084] Electrolyzer system 2 includes a controller 114 for central system control, which controls and / or regulates the anode-side and cathode-side system components 20 and 22, respectively, and their operation. The controller 114 is designed as a central control unit specifically developed for electrolyzer system 2.

[0085] The controller 114 has control functions and condition monitoring for controlling and / or regulating the anode-side and cathode-side plant systems 20 and 22, which are implemented in the controller 114 via software. The controller 114 is directly connected to peripheral devices in the plant systems 20 and 22 via signal transmission.The controller 114 is connected, for example, to at least one of the following peripheral devices: pump unit 30, throttle 32, limit valve 38, limit valve 40, temperature sensor 44, level sensor 46, hydrogen sensor 48, feed valve 56, discharge valve 58, pressure sensor 60, temperature sensor 62, conductivity sensor 64, throttle 68, temperature sensor 70, coolant valve 72, temperature sensor 74, pressure sensor 76, flow sensor 78, differential pressure sensor 80, temperature sensor 82, back pressure valve 92, temperature sensor 97, discharge valve 100, throttle 102, level sensor 104, level sensor 106, pressure sensor 108, temperature sensor 110, and flow sensor 112.

[0086] Plant systems 20 and 22 each have an assigned control loop 116, 118 on ( Fig. 2 to Fig. 5) The control loop 116 of the plant system 20 is hereinafter also referred to as anode control loop 116, and the control loop 118 of the plant system 22 is accordingly also referred to as cathode control loop 118.

[0087] The anode control loop 116 is suitable and configured to control and / or regulate the water supply 24 for the electrolysis unit 4. In particular, the anode control loop 116 is designed and configured to control and / or regulate a volume flow on the anode side, a volume flow of the coolant circuit 66, and the fresh water supply 50.

[0088] The cathode control loop 118 is suitable and configured for controlling and / or regulating the hydrogen removal unit 84. In particular, the cathode control loop 118 is designed and configured to control and / or regulate a back pressure or cathode pressure in the hydrogen removal unit 84 and a fill level of the water separator 86.

[0089] The anode control loop 116 and the cathode control loop 118 each have a controller 120 integrated into the controller 114 ( Fig. 2) and at least one peripheral or field device which is directly connected to the controller 114 via signal technology.

[0090] The following is based on the Fig. 1 A first embodiment of the anode control loop 116 is explained. In this embodiment, a water level in the water tank 42 is controlled and / or regulated. In other words, the anode control loop 116 is implemented here as a level control system.

[0091] The controller 114 is directly connected via signal technology to the level sensor 46 as a measuring element and to the feed valve 56 and the discharge valve 58 as actuators.

[0092] The anode control loop 116 regulates the fill level of the process water 12 in the water tank 42 to a desired setpoint as a reference variable, ensuring that sufficient process water 12 is always available for electrolysis in the water circuit 26. The measured fill level value from the level sensor 46 is fed back to the input of the controller 120, and the control deviation is calculated by subtracting it from the fill level setpoint. The controller 120 generates a valve control signal for both the feed valve 56 and the discharge valve 58 as the manipulated variable.

[0093] The following is based on the Fig. Figure 2 shows a second embodiment of the anode control loop 116. In this embodiment, the anode control loop 116 controls and / or regulates the cooling of the process water 12 or the water circuit 26.

[0094] In the illustrated embodiment, the temperature sensor 44 of the water tank 42 is omitted. In the water circuit 26, for example, a liquid sensor 122 for detecting the process water 12 and a temperature sensor 124 for detecting the water temperature are connected. The liquid sensor 122 is arranged between the water tank 42 and the pump unit 30, while the temperature sensor 124 is arranged between the ion exchanger 36 and the conductivity sensor 64.

[0095] The controller 114 is directly connected to the temperature sensor 74 as a measuring element and to the supply valve 56 and the coolant valve 72 as actuators via signal technology.

[0096] The anode control loop 116 regulates the water temperature of the process water 12 to a desired temperature setpoint 126 as a reference variable, so that the electrolysis of the electrolysis unit 4 can be carried out effectively. The measured temperature value from the temperature sensor 74 is fed back to the input of the controller 120, and the control deviation is calculated by subtracting it from the temperature setpoint 126. The controller 120 generates a valve control signal 129 for the coolant valve 72 as the manipulated variable.

[0097] The feed valve 56 is controlled by a pilot or feedforward control 128. The supplied fresh water has a lower water temperature than the process water in the water circuit 26, particularly in the circuit section between the water reservoir 28 and the electrolysis unit 4. As a result, the fresh water supply acts as a disturbance variable in the control loop of the anode control circuit 116 and is actively included in the control process.

[0098] The following are based on the Fig. 3 and Fig. Figure 4 shows three further embodiments of the anode control loop 116. In these embodiments, the anode control loop 116 is designed and configured to control and / or regulate the volume flow of the process water 12 into the electrolysis chamber 6.

[0099] In the first embodiment of the Fig. 3 the flow sensor 78 as measuring element of the anode control loop 116 and the limiting valves 38 and 40 as actuators of the anode control loop 116 are directly connected to the controller 114 via signal technology.

[0100] Controller 114, for example, has a stored flow setpoint of 130. The measured flow rate from flow sensor 78 is fed back, with the control deviation being calculated as the difference between the flow setpoint of 130 and the sensor reading. Based on this control deviation, controller 120 controls and / or regulates the limit valves 38 and 40 to adjust and / or regulate the volume flow of process water 12 entering the electrolysis chamber 6 to the flow setpoint of 130.

[0101] In the second embodiment of the Fig. 3 the limiting valve 38 is omitted, so that the anode control loop 116 only controls and / or regulates the limiting valve 40 depending on the flow sensor 78.

[0102] In the exemplary embodiment of the Fig. 4 The differential pressure sensor 80 as measuring element of the anode control circuit 116 and the pump unit 30 as actuators of the anode control circuit 116 are directly connected to the controller 114 via signal technology.

[0103] In this configuration, the anode control loop 116 directly controls and / or regulates the flow rate of the process water 12 supplied to the electrolysis unit 4 by means of the pump unit 30 based on a pressure differential on the anode side. In other words, the pump unit 30 is controlled and / or regulated depending on the anode pressure. Therefore, in this configuration, the limiting or bypass valves 38, 40 for flow rate control of the water circuit 26 can be omitted, since the flow rate is directly regulated and / or controlled by the pump operation. The system 20, or rather the water circuit 26, does not have a bypass or bypass line 40.

[0104] The measured pressure difference from the differential pressure sensor 80 is fed back and combined with a pressure difference setpoint dimensioned according to the desired flow rate to determine the control deviation for the controller 120. The controller 120 generates a corresponding pump signal for the pump unit 30 as the manipulated variable.

[0105] In the Fig. Figure 5 shows an embodiment of the cathode control loop 118. The cathode control loop 118 is designed and configured for controlling and / or regulating the cathode pressure, i.e., the hydrogen pressure on the cathode side or at the hydrogen distance 84.

[0106] In the exemplary embodiment of the Fig. 5 The pressure sensor 108 as measuring element of the cathode control loop 118 and the back pressure valve 92 as actuators of the cathode control loop 118 are directly connected to the controller 114 via signal technology.

[0107] The cathode pressure is detected by means of the pressure sensor 108 and fed back to the input of the controller 120 of the cathode control loop 118, which is integrated into the controller 114. The detected pressure value is subtracted from a setpoint pressure 134 and fed to the controller 120 as a control deviation, which generates a corresponding control signal for the back pressure valve 92.

[0108] In an advantageous embodiment, the pressure is increased by the inflow of gaseous hydrogen 16 and condensate from the electrolysis unit 4 and regulated via the counter-pressure valve 92.

[0109] The following is another embodiment of the cathode control loop 118 based on the Fig. 1 explained in more detail.

[0110] In this embodiment, the cathode pressure is controlled and / or regulated by the cathode control loop 118 via the power output of the electrolysis unit 4. For this purpose, the electrical power output of the electrolysis unit 4 is measured. To this end, the controller 114 is directly connected to a current and / or voltage sensor (not shown) in the DC circuit of the electrolysis unit 4 as a peripheral device, whereby the electrical power output of the electrolysis unit 4 is controlled and / or regulated by the pressure sensor 108, either additionally or alternatively to the back pressure valve 92.

[0111] The following is another embodiment of the cathode control loop 118 based on the Fig. 1 explained in more detail.

[0112] In this version, the cathode control loop 118 detects the fill level of the water separator 86 using the fill level sensor 104 or 106, and controls and / or regulates it by the cathode pressure.

[0113] The claimed invention is not limited to the embodiments described above. Rather, other variants of the invention can also be derived by a person skilled in the art within the scope of the disclosed claims without departing from the subject matter of the claimed invention. In particular, all individual features described in connection with the various embodiments can also be combined in other ways within the scope of the disclosed claims without departing from the subject matter of the claimed invention. Reference symbol list 2 Electrolyzer system 4 Electrolysis units 6 Electrolysis chamber 8 Cathode 10 Anode 12 Process water 14 Oxygen 16 Hydrogen 18 Proton exchange membrane 20 plant systems 22 plant system 24 Water supply 26 Water cycle 28 Water reservoir 30 Pump unit, peripheral device 32. Throttle, peripheral device 34 heat exchangers 36 ion exchangers 38 Limiting valve, peripheral device 40 Limiting valve, peripheral device 42 water containers 44 Temperature sensor, peripheral device 46 Level sensor, peripheral device 48 Hydrogen sensor, peripheral device 50 Fresh water supply 52 Supply line 54 Drain line 56 Feed valve, peripheral device 58 Drain valve, peripheral device 60 Pressure sensor, peripheral device 62 Temperature sensor, peripheral device 64 Conductivity sensor, peripheral device 66 Coolant circuit 68 Throttle, peripheral device 70 Temperature sensor, peripheral device 72 Coolant valve, peripheral device 74 Temperature sensor, peripheral device 76 Pressure sensor, peripheral device 78 Flow sensor, peripheral device 80 Differential pressure sensor, peripheral device 82 Temperature sensor, peripheral device 84 Hydrogen removal 86 water separators 88 heat exchangers 90 Condensate drain 92 Back pressure valve, peripheral device 94 Nitrogen supply 96 Nitrogen 97 Temperature sensor, peripheral device 98 Drain line 100 Drain valve, peripheral device 102 Throttle, peripheral device 104 Level sensor, peripheral device 106 Level sensor, peripheral device 108 Pressure sensor, peripheral device 110 Temperature sensor, peripheral device 112 Flow sensor, peripheral device 113 Coolant circuit 114 Controller 116 Anode control loop 118 Cathode feedback loop 120 controllers 122 Liquid sensor 124 Temperature sensor 126 Temperature setpoint 128 Feedforward control 129 Valve control signal 130 Flow rate setpoint 132 Pressure differential setpoint 134 Pressure setpoint

Claims

[1] Electrolyzer system (2), in particular a proton exchange membrane electrolyzer system, comprising - an electrolysis unit (4) for the electrolytic production of gaseous hydrogen (16) from liquid process water (12) by means of a cathode (8) and an anode (10), - an anode-side system (20) with a water supply (24) connected to the electrolysis unit (4) on the anode side for supplying process water (12) to the electrolysis unit (4), - a cathode-side system (22) with a hydrogen removal system (84) connected to the electrolysis unit (4) on the cathode side for removing the generated hydrogen (16) from the electrolysis unit (4), and - a controller (114) for central plant control, which controls and / or regulates the anode-side plant system (20) and the cathode-side plant system (22). [2] Electrolyzer system (2) according to claim 1, characterized by , - that the anode-side system (20) has at least one anode control loop (116) for controlling and / or regulating the water supply (24), - that the cathode-side system (22) has at least one cathode control loop (118) for controlling and / or regulating the hydrogen removal (84), - wherein the anode control loop (116) and the cathode control loop (118) each have a controller (120) integrated into the controller (114) and at least one peripheral device (30, 32, 38, 40, 44, 46, 48, 56, 58, 60, 62, 64, 70, 72, 74, 76, 78, 80, 82, 92, 97, 100, 102, 104, 106, 108, 110, 112) which is directly connected to the controller (114) via a signal connection. [3] Electrolyzer system (2) according to claim 1 or 2, characterized by, that control functions and condition monitoring for controlling and / or regulating the anode-side system (20) and the cathode-side system (22) are implemented in software in the controller (114). [4] Electrolyzer system (2) according to claim 2 or 3, characterized by , that the water supply (24) has a water reservoir (28) coupled to a fresh water supply (50), wherein the anode control loop (116) controls and / or regulates a supply of new process water from the fresh water supply (50) into the water reservoir (28) depending on a fill level of the water reservoir (28). [5] Electrolyzer system (2) according to any one of claims 2 to 4, characterized by, that the water supply (24) has a heat exchanger (34) for temperature control of the process water (12) supplied to the electrolysis unit (4), wherein the heat exchanger (34) is connected to a coolant circuit (66), and wherein the anode control circuit (116) controls and / or regulates a temperature of the process water (12). [6] Electrolyzer system (2) according to claim 5, characterized by , that the anode control loop (116) controls and / or regulates the temperature of the process water (12) by means of a coolant volume flow in the coolant circuit (66). [7] Electrolyzer system (2) according to claim 5 or 6, characterized by , that the anode control loop (116) controls and / or regulates the temperature of the process water (12) by supplying new process water (12) from the fresh water supply (50) into the water reservoir (28). [8] Electrolyzer system (2) according to claim 7, characterized by, that the supply of new process water (12) from the fresh water supply (50) into the water reservoir (28) is controlled by a pre-control (128) of the controller (114). [9] Electrolyzer system (2) according to any one of claims 2 to 8, characterized by , that the anode control loop (116) controls and / or regulates a volume flow of the process water (12) supplied to the electrolysis unit (4). [10] Electrolyzer system (2) according to claim 9, characterized by , that the anode control loop (116) has a flow sensor (78) for detecting the volume flow of the process water (12) supplied to the electrolysis unit (4) and a limiting valve (38, 40) for adjusting this volume flow as peripheral devices. [11] Electrolysis plant (2) according to claim 10, characterized by , that the limiting valve (40) is connected in parallel as a bypass valve of the electrolysis unit (4). [12] Electrolyzer system (2) according to claim 9, characterized by, that the water supply (24) has a pump unit (30) for conveying the process water (12), and that the anode control loop (116) controls and / or regulates the volume flow of the process water (12) supplied to the electrolysis unit (4) by means of the pump unit (30) on the basis of a pressure difference of the anode side of the electrolysis unit (4). [13] Electrolysis plant (2) according to any one of claims 2 to 12, characterized by , that the hydrogen removal (84) includes a water separator (86) for separating liquid process water (12) from the generated gaseous hydrogen (16), and that the cathode control loop (118) controls and / or regulates a cathode pressure in the water separator (86). [14] Electrolysis plant (2) according to claim 13, characterized by , that the cathode control loop (118) controls and / or regulates the cathode pressure by means of a counter-pressure valve (92) connected to the water separator (86). [15] Electrolysis plant (2) according to claim 13 or 14, characterized by , that the cathode control loop (118) controls and / or regulates the cathode pressure by controlling and / or regulating a power of the electrolysis unit (4). [16] Electrolyzer system (2) according to claim 13, characterized by , - that the water separator (86) has a level sensor (104, 106), and - that the cathode control loop (118) controls and / or regulates the fill level of the water separator (86) via the cathode pressure.

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