Electrolysis device for producing a fuel

Abstract

The present invention relates to an electrolysis device (100) for producing a fuel (B) in electrolysis cells of at least one electrolysis stack (110), comprising an air supply portion (122) for supplying feed air (ZL) to an air side (120) of the electrolysis stack (110) and an air discharge portion (124) for discharging exhaust air (AL) from the air side (120) of the electrolysis stack (110), and also comprising a water supply portion (132) for supplying water (W) to a fuel side (130) of the electrolysis stack (110) and a fuel discharge portion (134) for discharging fuel mixture (BG), which comprises fuel (B) and water (W), from the fuel side (130) of the electrolysis stack (110), wherein: the fuel discharge portion (134) has a condenser device (140) for cooling the fuel mixture (BG) to below a condensation temperature of water (W), for condensing the water (W) and separating the water from the fuel (B); in the fuel discharge portion (134), upstream of the condenser device (140), a fuel-mixture / feed-air heat exchanger (150) is arranged in heat-transferring contact with the air supply portion (122) for transferring heat from the fuel mixture (BG) to the feed air (ZL).

Description

[0001] ELECTROLYSIS DEVICE FOR PRODUCING A FUEL

[0002] The present invention relates to an electrolysis device for producing a fuel, a control method for controlled operation of such an electrolysis device and a computer program product for carrying out such a control method.

[0003] It is known that electrolysis devices are used to generate a fuel from available electrical power. For example, hydrogen can be generated as a fuel, which is then stored directly as a chemical energy carrier or further processed for storage using additional chemical processes. Such systems are also referred to as power-to-gas systems and can be used, for example, to chemically store electricity generated from renewable sources, such as solar panels or wind energy, as gas in the respective fuel for the long term. It is also known to use electrolysis devices for such systems, which in particular enable the electrolytic splitting of water into its gas components. Such electrolysis devices are usually constructed from a large number of individual electrolysis cells that are stacked one above the other in at least one electrolysis stack.

[0004] During operation of these electrolysis devices, water is evaporated and fed as water vapor, preferably as a gas with a vapor content of 60% to 80%, to the electrolysis cells and thus to the electrolysis stack on its fuel side. On the other side of the respective cell membrane in each electrolysis cell, which can also be referred to as the air side, supply air is sucked in from the environment, for example, and fed in. Using the supplied electrical energy, at least a portion of the vaporous water is split into its components oxygen and hydrogen. This results in a mixture of the produced fuel, in particular the hydrogen, and remaining residual water vapor forming the fuel mixture on the fuel side. On the air side, an exhaust gas remains which is enriched with the produced oxygen.The fuel mixture exits the fuel side, while the exhaust air exits the electrolysis stack separately from the air side. A disadvantage of the known solutions is that, in addition to using electrical energy for the electrolysis processes, a high level of effort is also required for the thermal operating parameters. For example, it is necessary to evaporate the supplied water to a high degree, particularly completely or essentially completely, in order to achieve the described water vapor content of 60% to 80%. This is partly achieved by electrical heating devices, meaning that electrical power is lost for heating and is therefore not available for the electrolysis process.

[0005] In addition, it is necessary to separate the resulting fuel mixture, i.e., to separate the remaining water vapor from the fuel. This is typically done using condensers that cool the fuel mixture below the condensation temperature of water. External coolants with a separate cooling circuit are used to ensure this cooling functionality. The coolant in the circuit is also cooled by separate cooling devices using electrical energy. Additional electrical energy is therefore required here to ensure thermally balanced operation of the electrolysis device. This results in a loss of efficiency both in heating the water to steam and in cooling.

[0006] The same applies to the air supply section, where the supply air must be electrically preheated for thermally balanced operation with equal temperatures on the air and fuel sides. Here, too, electrical energy is required to operate the electrolysis device and is therefore not available for the electrolysis functionality.

[0007] The object of the present invention is to at least partially remedy the disadvantages described above in a cost-effective and simple manner. In particular, the object of the present invention is to increase or even optimize the energy efficiency during the operation of an electrolysis device in a cost-effective and simple manner.

[0008] The above object is achieved by an electrolysis device having the features of claim 1, a control method having the features of claim 11, and a computer program product having the features of claim 15. Further features and details emerge from the subclaims, the description, and the drawings. Features and details described in connection with the electrolysis device according to the invention naturally also apply in connection with the control method according to the invention and the computer program product according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0009] According to the invention, an electrolysis device is used to produce a fuel in electrolysis cells of at least one electrolysis stack. For this purpose, the electrolysis device has an air supply section for supplying supply air to an air side of the electrolysis stack and an air discharge section for discharging exhaust air from the air side of the electrolysis stack. Furthermore, a water supply section for supplying water to a fuel side of the electrolysis stack and a fuel discharge section for discharging a fuel mixture comprising fuel and water from the fuel side of the electrolysis stack are provided. An electrolysis device according to the invention is characterized in that the fuel discharge section has a condenser device for cooling the fuel mixture below a condensation temperature of water, for condensing and separating the water from the fuel.In addition, in the fuel discharge section upstream of the condenser device, a fuel mixture-supply air heat exchanger is arranged in heat-transferring contact with the air supply section for transferring heat from the fuel mixture to the supply air.

[0010] An electrolysis device according to the invention is based on known electrolysis devices and serves to generate fuel. While, in principle, any form of fuel can be generated, this will be explained in more detail in the context of the present patent application essentially with reference to the fuel in the form of hydrogen. The hydrogen can directly represent the fuel for subsequent use or be further processed. For example, the hydrogen fuel can be converted into methane or other carbon-containing fuel gases through a methanation process.

[0011] The core idea of ​​the invention is to increase energy efficiency and reduce electrical cooling and heating requirements, which are usually generated by electrical cooling and heating options. For this purpose, the electrolysis device according to the invention is designed, on the one hand, with a condenser device capable of separating the individual components in the fuel mixture from one another. By cooling the fuel mixture below the condensation temperature of water, the residual water vapor still remaining in the fuel mixture will condense and be easily separated from the still gaseous fuel, for example the hydrogen. Water separators capable of easily separating the condensed liquid water from the still gaseous fuel, for example, can be provided, either integrated into the condenser device or arranged downstream.

[0012] According to the invention, a heat exchanger in the form of a fuel mixture / supply air heat exchanger is arranged upstream of this condenser device. This leads to several significant advantages. The fuel mixture leaving the electrolysis stack from the fuel side has the operating temperature of the electrolysis stack. This high temperature includes, in particular, the operating temperature significantly above the condensation temperature of water. As it flows through the fuel mixture / supply air heat exchanger, this fuel mixture transfers at least a portion of the heat it contains to the supply air flowing through the heat exchanger on the other side. In other words, the supply air is preheated and the fuel mixture is cooled.In this case, it is preferred, as will be explained in more detail later with reference to a control method, that the temperature of the fuel mixture is reduced in such a way that, in particular, the condensation temperature of water is not yet reached, so that the water remains in gaseous vapor form. Since the water vapor can still make up to 20% to 40% of the fuel mixture, depending on the operating situation, it is advantageous to keep it in the vapor phase in order to provide for simple and purely gaseous transport to the condenser device.

[0013] The reduced temperature in the fuel mixture now results in the required cooling capacity at the condenser device being significantly reduced compared to known electrolysis devices. The temperature difference between the inlet temperature of the fuel mixture at the condenser device and the condensation temperature of water, which must be below this temperature, is reduced in the inventive design compared to known devices. This reduction is based on the fact that the fuel mixture has already transferred some of its heat to the supply air in the fuel mixture-supply air heat exchanger added in the inventive design. Because the condenser device now has to provide a lower cooling capacity with a reduced temperature difference, a correspondingly lower circulation cooling of the coolant used is also necessary.The required electrical cooling capacity is reduced accordingly here, since there is less heating of the coolant in the condenser device.

[0014] At the same time, the heat is transferred to the supply air, which is then preheated. The preheated supply air now only needs to be heated to the desired operating temperature in the electrolysis stack by a reduced temperature difference. As already explained in the introduction, in operational conditions the operating temperatures on the air and fuel sides in the electrolysis stack are preferably at the same level and thus in balance. Because the supply air is now at least partially preheated from an outside temperature by absorbing heat from the fuel mixture, the temperature difference that must then be generated by an electric heating device to heat the supply air to the desired balanced operating temperature in the electrolysis stack is reduced.Here it is clearly visible that an energy advantage is now also achieved on the supply air side of the air supply section, since the necessary electrical heating output is reduced accordingly.

[0015] In summary, on the fuel side, the required cooling capacity and the associated electrical cooling capacity are reduced. On the supply air side, the correspondingly required electrical heating functionality for the supply air is reduced, so that overall, from the same amount of available electrical power, for example, from a renewable energy generator, more of the available electrical power is actually available for the electrolysis function. Due to the reduced operating costs from an energy perspective according to the invention, the operating efficiency of the electrolysis device is significantly increased compared to known devices.Because the heat is now exchanged specifically between two operating media, namely the fuel mixture on the one hand and the supply air on the other, which must be specifically cooled (fuel mixture) and heated (supply air), this heat transfer also leads to a double increase in efficiency. This means that a double energy reduction can be achieved with a single structural change to the electrolysis device.

[0016] It can be advantageous if, in an electrolysis device according to the invention, a fuel mixture-water heat exchanger is arranged in the fuel discharge section upstream of the fuel mixture-supply air heat exchanger for transferring heat from the fuel mixture to the water. In other words, an additional increase in efficiency is now possible here by also transferring heat from the fuel mixture to the water in the water supply section. This makes it possible, particularly upstream of the fuel mixture-supply air heat exchanger, to utilize the high outlet temperature of the fuel mixture directly after it leaves the electrolysis stack to provide additional heating functionality for the supplied water.Since the outlet temperature of the fuel mixture is particularly close to the operating temperature and thus above the condensation temperature of water, this correspondingly high temperature of the fuel mixture can even be used to provide a superheating function for the supplied, already vaporous water. This means that, for example, further heat exchangers or heating devices can be arranged upstream of this fuel mixture-water heat exchanger in the water supply section to ensure appropriate evaporation of the water. In such a case, the fuel mixture-water heat exchanger serves to ensure the possibility of superheating the water vapor in the water supply section through the high outlet temperature of the fuel mixture.At the same time, an initial cooling of the fuel mixture will also take place at this point, so that in the interaction of the fuel mixture-water heat exchanger and the fuel mixture-supply air heat exchanger, an even further reduced temperature of the fuel mixture can now be expected as the inlet temperature at the condenser device. Since, in addition, additional internal heat utilization is now possible through the reuse of the heat on the water supply section side, this enables a further increase in the efficiency of the operation of the electrolysis device. It is also advantageous if, in an electrolysis device according to the invention, an electric supply air heating device is arranged in the air supply section downstream of the fuel mixture-supply air heat exchanger for electrically heating the supply air.Because this electric supply air heater is now located downstream of the fuel mixture-supply air heat exchanger, the supply air will have a correspondingly increased inlet temperature at this electric supply air heater due to the absorption of heat from the fuel mixture. The necessary remaining and reduced residual temperature difference for heating to the desired operating temperature in the electrolysis stack must now be provided by the electric supply air heater. Due to the reduced temperature difference still required, the previously explained reduced electrical power is sufficient, so that the described efficiency increase is achieved.

[0017] It is also advantageous if, in an electrolysis device according to the invention, the air supply section has an air supply bypass section with an air supply bypass valve, which can guide air supply past the fuel mixture / air supply heat exchanger in a controlled manner. Such a controlled bypass functionality can be designed both qualitatively and quantitatively. For example, the air supply bypass valve can be a simple control valve that can be set to an open and a closed state, so that the bypass can be opened or closed, so to speak. Of course, it is also possible to combine such an air supply bypass valve with a corresponding control valve for the fuel mixture / air supply heat exchanger, so that the line to the fuel mixture / air supply heat exchanger can be completely closed and thus this heat transfer functionality can be switched off, so to speak.The bypass allows, in particular, the flow rate of supply air through the fuel mixture supply air heat exchanger and thus the heat absorption capacity to be quantitatively controlled, thus adjusting the amount of heat transferred to this fuel mixture supply air heat exchanger. Controlling the transferred heat results in, in particular, the outlet temperature of the fuel mixture at the fuel mixture supply air heat exchanger being controllable. This makes it possible to ensure, in a simple and cost-effective manner, that maximum heat transfer is achieved without the temperature of the fuel mixture at the outlet of the fuel mixture supply air heat exchanger falling below the condensation temperature of water. This only occurs after entry into the downstream condenser device in the fuel discharge section.

[0018] It is also advantageous if, in an electrolysis device according to the invention, a cold recirculation section connects the fuel discharge section downstream of the condenser device to the water supply section in a fluid-communicating manner. This cold recirculation refers in particular to a recirculation of pure fuel, since the water has already been condensed and preferably separated by the preceding condensation. The recirculation of fuel serves to improve the operating mode and, in particular, the efficiency, and, depending on the operating situation, to avoid or at least minimize undesirable damage mechanisms in the electrolysis cells. This recirculation can preferably be directly controlled using a corresponding recirculation valve.Cold recirculation can also be carried out on the water supply side before all heating steps, so that a simple mixing of the cold fuel and the supplied cold water is sufficient.

[0019] It is further advantageous if, in an electrolysis device according to the invention, a recirculation fan is arranged in the cold recirculation section according to the preceding paragraph. A recirculation fan can also be understood as a forced-conveyor or active-conveyor fan, which accordingly ensures active recirculation. Depending on the operating situation, such a recirculation fan can also have a blocking function to control the recirculation rate or even completely set it to zero.

[0020] Further advantages are achieved if, in an electrolysis device according to the invention, a warm recirculation section fluidly connects the fuel discharge section downstream of the condensation device to the water supply section. Such a warm recirculation section can be provided in addition to or alternatively to the cold recirculation section described above. The warm recirculation section circulates a fuel mixture that has not yet been cooled or has only been cooled slightly, compared to the cold fuel in a cold recirculation section. It serves to recirculate the high-temperature fuel mixture into the water at a position where this water has also already undergone partial heating.In particular, the introduction of the warm recirculation gas in the form of the warm fuel mixture enables mixing with the supplied water, particularly in vapor form, so that heat transfer through the recirculation into the supplied water in the water supply section can also be achieved in this way. Control valves are, of course, also possible here to control or even regulate the recirculation in the warm recirculation section.

[0021] It is advantageous if, in an electrolysis device according to the invention according to the preceding paragraph, the water supply section has a recirculation ejector device into which the warm recirculation section opens. Such a recirculation ejector device allows, on the one hand, to provide pressurized, active recirculation support. Furthermore, the recirculation ejector device further serves a mixing function of the recirculated fuel mixture with the supplied water, which in this case already has a vaporous water vapor configuration.

[0022] Further advantages can also be achieved if, in an electrolysis device according to the invention, the warm recirculation section fluidly connects the fuel discharge section downstream of the fuel mixture / supply air heat exchanger to the water supply section. This warm recirculation can even be referred to as hot recirculation, since it is positioned even further upstream from the condenser device and, in particular, allows the fuel mixture to recirculate before flowing through the fuel mixture / supply air heat exchanger.

[0023] Furthermore, it is advantageous if, in an electrolysis device according to the invention, the warm recirculation section connects the fuel discharge section downstream of a fuel mixture-water heat exchanger to the water supply section in a fluid-communicating manner. This makes it possible to utilize the maximum temperature difference as the outlet temperature from the electrolysis stack while still in the fuel mixture-water heat exchanger for heat transfer and subsequently to conduct the still-warm components of the fuel mixture through the warm recirculation section.

[0024] The present invention also relates to a control method for controlled operation of an electrolysis device of the present invention. Such a control method is characterized by the following steps: dry heating by introducing and electrically heating supply air through the air supply section and protective gas through the water supply section until a first temperature threshold is reached,

[0025] - Moist heating by introducing and electrically heating supply air through the air supply section and at least partially water through the water supply section until a second temperature threshold above the first temperature threshold is reached,

[0026] - Increase the supplied quantities of water and / or supply air until a nominal load of the electrolysis device is reached.

[0027] A control method according to the invention offers the same advantages as those explained in detail with reference to an electrolysis device according to the invention. The decisive factor here is, in particular, the heating process in two stages: dry heating in a first step and moist heating in a second step. Dry heating is also referred to as preheating and serves to achieve a temperature in the electrolysis stack that lies above the first temperature threshold, particularly with the aid of electrically heated supply air. This first temperature threshold is determined in particular by the condensation temperature of water.If the operating temperature of the electrolysis cell exceeds this first temperature threshold, the high temperature in the electrolysis stack will prevent any water vapor supplied from condensing therein, but will instead flow through the electrolysis stack in vapor form. Heating is achieved with heated supply air on the air side and a protective gas on the fuel side. The protective gas serves to ensure that no damage mechanisms occur to the membranes of the electrolysis cells during the heating process, particularly during the dry heating step. Furthermore, the protective gas provides a counterpressure, so that undesirable pressure differences between the fuel side and the supply air side can be essentially eliminated.

[0028] Once the first temperature threshold has been exceeded, water can be introduced in addition to the protective gas or completely as an alternative to the protective gas. It can be evaporated using the integrated heating options and then passed through the electrolysis stack in vapor form on the fuel side. In this way, the heating process continues as a wet heating step until the second temperature threshold, specifically the operating temperature of the electrolysis stack, has been reached. Once the desired heating temperature has been reached, the operating conditions can be considered met, and the quantities of water and / or supply air can be increased.

[0029] It is advantageous if, in a control method according to the invention, a hot standby state is maintained after the second temperature threshold has been reached by means of moist heating, in which the supplied quantities of water and supply air are reduced to a minimum value in order to maintain the temperature at or above the second temperature threshold. This standby operation or standby state can also be understood to mean that shutdown should be avoided depending on the current operating situation. If, for example, the electrolysis device is connected to a system with a renewable energy generation device, for example with a solar park or a wind turbine, the available electrical power is usually fluctuating, since the production of these renewable energy generators also fluctuates.To accommodate this fluctuation, the electrolysis device can now be placed in a hot standby state using this control method, essentially waiting for the increase in electrical power while still remaining in the hot operating state for a quick response. In other words, the hot operating state allows the electrolysis device to react quickly to an increase in the electrical power produced by the connected electrical generators.

[0030] It is further advantageous if, in a control method according to the invention, a gas purging process is carried out for the fuel side of the electrolysis stack before increasing the supplied quantities of water and / or supply air. This purging process can also be referred to as a purge process. It serves in particular to remove protective gas or other undesirable gas components from the fuel side in order to ensure that no undesirable chemical processes or other damaging mechanisms occur in the electrolysis stack when the electrolysis functionality starts up. Furthermore, it can be advantageous if, in a control method according to the invention, the supplied quantities of water and / or supply air are increased in a first partial step until a partial load is reached and in a further partial step until the nominal load is reached.Of course, two or more such partial steps can also be performed. Reaching partial load serves, in particular, to slowly reach and pass through one or more equilibrium situations in order to avoid the risk of non-stoichiometric distributions within the electrolysis stack for short periods of time and thus reduce or even completely eliminate undesirable chemical damage mechanisms.

[0031] A further subject matter of the present invention is a computer program product comprising instructions which, when executed by a computer, cause the computer to carry out the steps of a control method according to the invention. Thus, a computer program product according to the invention brings with it the same advantages as have been explained in detail with reference to a control method according to the invention.

[0032] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. They show schematically:

[0033] Fig. 1 shows an embodiment of an electrolysis device according to the invention,

[0034] Fig. 2 shows a further embodiment of an electrolysis device according to the invention,

[0035] Fig. 3 shows a further embodiment of an electrolysis device according to the invention,

[0036] Fig. 4 shows a further embodiment of an electrolysis device according to the invention and

[0037] Fig. 5 shows a further embodiment of an electrolysis device according to the invention. Figure 1 schematically shows an electrolysis device 100 according to the invention. This is equipped here with an electrolysis stack 110, which schematically has an air side 120 and a fuel side 130. Of course, in the actual design, the individual electrolysis cells and, accordingly, the gas flow can be designed to be much more complex. For the schematic operation shown here, an air supply section 122 and an air discharge section 124 are provided for the air side 120. Thus, supply air ZL can be fed from the environment into the air side 120 and from there, after the chemical conversion during the electrolysis reaction, can be discharged back to the environment as exhaust air AL via the air discharge section 124, for example.On the fuel side 130, water W is supplied via the water supply section 132 and fuel mixture BG produced by the electrolysis reaction is discharged via the fuel discharge section 134.

[0038] As has been explained, the water W is supplied in particular as steam, although this is not yet shown in more detail in Figure 1. The water W can be supplied externally in the form of steam, or it can be evaporated from liquid water W by heating options integrated into the electrolysis device 100. The steam content in the water W is preferably in the range between 60% and 80% when it enters the fuel side 130. During the conversion in the electrolysis stack 110, a portion of the steam will remain in steam form, so that the fuel mixture BG comprises, on the one hand, fuel B and, on the other hand, 20% to 40% water W in the form of steam.

[0039] The core concept of the invention is based on the fact that internal heat recirculation takes place. Upon exiting the fuel side 130, the fuel mixture BG is at the corresponding operating temperature of the electrolysis stack 110. This hot fuel mixture BG is then first passed in the fuel discharge section 134 via the fuel mixture-supply air heat exchanger 150. Here, heat is transferred from the fuel mixture BG to the supply air ZL in the air supply section 122. In other words, in this fuel mixture-supply air heat exchanger 150, the temperature of the fuel mixture BG is reduced and the temperature of the supply air ZL is increased. The reduced temperature of the fuel mixture BG now leads to a reduced inlet temperature at the condenser device 140 arranged further downstream in the fuel discharge section 134.This is schematically provided here as a cooling heat exchanger operated with an external coolant (not shown in detail) and additionally equipped with a water separator. Further reducing the temperature of the fuel mixture BG in the condenser device 140 below the condensation temperature of water W condenses the vaporous water W and separates this liquid water W from the gaseous fuel B, which is configured in particular as hydrogen. This makes it possible to remove the separated fuel B from the electrolysis device 100 and feed it to a storage or further processing facility.

[0040] As Figure 1 clearly shows, the internal recovery now reduces the electrical expenditure required for the remaining condensation cooling at the condenser device 140, as well as the remaining heating requirement for the supply air ZL, so that the overall efficiency of the electrolysis device 100 can be increased.

[0041] Figure 2 further develops the embodiment of Figure 1 in two places. Firstly, a fuel mixture-water heat exchanger 160 is now additionally provided upstream of the fuel mixture-supply air heat exchanger 150. This will bring the fuel mixture BG into heat-transferring contact with the water W at the hottest point of the fuel discharge section 134 and serves in particular to superheat the water W, which is preferably already in vapor form at this point. Here, a first reduction in the temperature of the fuel mixture BG takes place. In the fuel mixture-supply air heat exchanger 150, a further temperature reduction of the fuel mixture BG is now carried out, as explained with reference to Figure 1.

[0042] Figure 2 further shows the possibility of controlling the fuel mixture-supply air heat exchanger 150 with regard to heat transfer, at least on one side. For example, it is possible here to open and close a supply air bypass section 121 with a supply air bypass valve 123 in a controlled manner, particularly quantitatively. This makes it possible to control the flow rates through the bypass section 122 and thus also on the supply air ZL side through the fuel mixture-supply air heat exchanger 150, and in this way to adjust the transferred heat and, indirectly, the outlet temperature of the fuel mixture BG from the fuel mixture-supply air heat exchanger 150. It is further advantageous if, according to Figure 3, an electrolysis device 100 now has a cold recirculation section 180. This now connects the fuel discharge section 134 downstream of the condenser device 140 with the water supply section 132.Here, after the condensation separation, pure or essentially pure fuel B with a temperature below the condensation temperature of water is fed to the water W in the water supply section 132. This can be carried out, in particular, as active cold recirculation by operating the recirculation fan 182 shown here accordingly.

[0043] Furthermore, the embodiment of Figure 3 now shows an electrical supply air heating device 170 in the air supply section 122. This serves to ensure heating of the already preheated supply air ZL to the desired operating temperature of the electrolysis stack 110 with reduced electrical expenditure.

[0044] Figure 4, similar to Figure 3, also shows a recirculation option. However, the electrolysis device 100 shown here is a warm recirculation section 190, which provides the connection between the fuel discharge section 134 and the water supply section 132 with the still-warm fuel mixture BG. For this purpose, the recirculation is carried out upstream of the fuel mixture-supply air heat exchanger 150 and preferably downstream of the fuel mixture-water heat exchanger 160. Here, too, introduction into a recirculation ejector device 192 takes place, which accordingly serves to ensure active recirculation, as well as mixing of the fuel mixture BG with the water W.

[0045] Figure 5 shows a combination of the embodiments of Figure 4 and Figure 3. The electrolysis device shown here therefore has both the warm recirculation section 190 and a cold recirculation section 180.

[0046] The above explanation of the embodiment describes the present invention exclusively within the framework of examples. List of reference symbols

[0047] 100 electrolysis device

[0048] 110 electrolysis stacks

[0049] 120 airside

[0050] 121 bypass section

[0051] 122 Air supply section

[0052] 123 Supply air bypass valve

[0053] 124 Air discharge section

[0054] 130 Fuel side

[0055] 132 Water supply section

[0056] 134 Fuel removal section

[0057] 140 Capacitor device

[0058] 150 fuel mixture supply air heat exchanger

[0059] 160 fuel mixture-water heat exchanger

[0060] 170 electric supply air heater

[0061] 180 cold recirculation section

[0062] 182 recirculation fans

[0063] 190 warm recirculation section

[0064] 192 Recirculation ejector device

[0065] B Fuel

[0066] BG fuel mixture

[0067] ZL supply air

[0068] AL exhaust air

[0069] W Water

Claims

Patent claims 1 . Electrolysis device (100) for producing a fuel (B) in electrolysis cells of at least one electrolysis stack (110), comprising an air supply section (122) for supplying supply air (ZL) to an air side (120) of the electrolysis stack (110) and an air discharge section (124) for discharging exhaust air (AL) from the air side (120) of the electrolysis stack (110), further comprising a water supply section (132) for supplying water (W) to a fuel side (130) of the electrolysis stack (110) and a fuel discharge section (134) for discharging a fuel mixture (BG) comprising fuel (B) and water (W) from the fuel side (130) of the electrolysis stack (110), characterized in that the fuel discharge section (134) has a condenser device (140) for cooling the fuel mixture. (BG) below a condensation temperature of water (W), for condensing and separating the water (W) from the fuel (B),wherein in the fuel discharge section (134) upstream of the condenser device (140) a fuel mixture-supply air heat exchanger (150) is arranged in heat-transferring contact with the air supply section (122) for transferring heat from the fuel mixture (BG) to the supply air (ZL)., 2. Electrolysis device (100) according to claim 1, characterized in that in the fuel discharge section (134) upstream of the fuel mixture-supply air heat exchanger (150) a fuel mixture-water heat exchanger (160) is arranged in heat-transferring contact with the water supply section (132) for transferring heat from the fuel mixture (BG) into the water (W).

3. Electrolysis device (100) according to one of the preceding claims, characterized in that an electrical supply air heating device (170) for electrically heating the supply air (ZL) is arranged in the air supply section (122) downstream of the fuel mixture-supply air heat exchanger (150).

4. Electrolysis device (100) according to one of the preceding claims, characterized in that the air supply section (122) has a supply air bypass section (121) with a supply air bypass valve (123), which can guide supply air (ZL) past the fuel mixture-supply air heat exchanger (150) in a controlled manner.

5. Electrolysis device (100) according to one of the preceding claims, characterized in that a cold recirculation section (180) connects the fuel discharge section (134) downstream of the condenser device (140) in fluid communication with the water supply section (132).

6. Electrolysis device (100) according to claim 5, characterized in that a recirculation fan (182) is arranged in the cold recirculation section (180).

7. Electrolysis device (100) according to one of the preceding claims, characterized in that a warm recirculation section (190) connects the fuel discharge section (134) upstream of the condenser device (140) in fluid communication with the water supply section (132).

8. Electrolysis device (100) according to claim 7, characterized in that the water supply section (132) has a recirculation ejector device (192) into which the warm recirculation section (190) opens.

9. Electrolysis device (100) according to one of claims 7 or 8, characterized in that the warm recirculation section (190) connects the fuel discharge section (134) upstream of the fuel mixture supply air heat exchanger (150) in fluid communication with the water supply section (132).

10. Electrolysis device (100) according to one of claims 7 to 9, characterized in that the warm recirculation section (190) connects the fuel discharge section (134) downstream of a fuel mixture-water heat exchanger (160) in fluid communication with the water supply section (132). 1 1. Control method for controlled operation of an electrolysis device (100) having the features of one of claims 1 to 10, characterized by the following steps: - Dry heating by introducing and electrically heating supply air (ZL) through the air supply section (122) and protective gas through the water supply section (132) until a first temperature threshold is reached, - Moist heating by introducing and electrically heating supply air (ZL) through the air supply section (122) and at least partially water (W) through the water supply section (132) until a second temperature threshold above the first temperature threshold is reached, - Increasing the supplied quantities of water (W) and / or supply air (ZL) until a nominal load of the electrolysis device (100) is reached.

12. Control method according to claim 11, characterized in that after reaching the second temperature threshold by means of moist heating, a hot standby state is maintained, in which the supplied quantities of water (W) and supply air (ZL) are reduced to a minimum value in order to maintain the temperature at or above the second temperature threshold.

13. Control method according to one of claims 11 or 12, characterized in that before increasing the supplied quantities of water (W) and / or supply air (ZL), a gas purging process is carried out for the fuel side (130) of the electrolysis stack (110).

14. Control method according to one of claims 11 to 13, characterized in that the increase in the supplied quantities of water (W) and / or supply air (ZL) is carried out in a first sub-step until a partial load is reached and a further sub-step until the nominal load is reached.

5. A computer program product comprising instructions which, when executed by a computer, cause the computer to carry out the steps of a control method having the features of one of claims 11 to 14.

Images