Alkaline electrolysis device

Abstract

The invention relates to an alkaline electrolysis device comprising: - at least one electrolysis cell comprising a reaction chamber comprising a hydrogen-side reaction chamber region accommodating an aqueous electrolyte for decomposing the aqueous electrolyte into gaseous hydrogen and comprising an oxygen-side reaction chamber region accommodating an aqueous electrolyte for decomposing the aqueous electrolyte into gaseous oxygen; - a hydrogen separator connected with the hydrogen-side reaction chamber region for separating the aqueous electrolyte introduced into the hydrogen separator from the gaseous hydrogen and an oxygen separator connected with the oxygen-side reaction chamber region for separating the aqueous electrolyte introduced into the oxygen separator from the gaseous oxygen; wherein the hydrogen separator has a first hydrogen separator outlet for draining the aqueous electrolyte having a first hydrogen concentration and a second hydrogen separator outlet for draining the aqueous electrolyte having a second hydrogen concentration lower than the first hydrogen concentration; and wherein the first hydrogen separator outlet and the second hydrogen separator outlet are connected or connectable with the reaction chamber.

Description

Technical Field

[0001] The present invention relates to an alkaline electrolysis apparatus for decomposing an aqueous electrolyte into hydrogen and oxygen, comprising: at least one electrolytic cell having a reaction chamber including a hydrogen-side reaction chamber region and an oxygen-side reaction chamber region; a hydrogen separator for separating the aqueous electrolyte introduced into the hydrogen separator from gaseous hydrogen; and an oxygen separator for separating the aqueous electrolyte introduced into the oxygen separator from gaseous oxygen. Background Technology

[0002] In an alkaline electrolysis unit, the chemical half-reactions in the hydrogen-side and oxygen-side reaction chamber regions result in corresponding concentration gradients of aqueous electrolytes. Therefore, thorough mixing of the two electrolyte streams is essential, and these two electrolyte streams must first exit the reaction chamber before one or more fully mixed electrolyte streams can be resupplyed to the reaction chamber.

[0003] Because 100% gas separation cannot be achieved in practical applications in hydrogen and oxygen separators, gaseous impurities appear in the well-mixed electrolyte stream. Within the framework of this invention, gaseous impurities are specifically understood to refer to gaseous and / or dissolved hydrogen being supplied to the oxygen-side reaction chamber region in a manner exceeding a percentage limit. Conversely, gaseous and / or dissolved oxygen is supplied to the hydrogen-side reaction chamber region in a manner exceeding a percentage limit. Typically, this limit is not allowed to exceed 2% on either side, as otherwise there is a risk of forming an explosive hydrogen-oxygen mixture.

[0004] Alkaline electrolysis devices are known from the prior art. Such devices are described in the non-patent literature "Influence of process conditions on gas purity in alkaline water electrolysis" by P. Haug, M. Koj, and T. Turek, International Journal of Hydrogen Energy, pp. 9406-9418, 2017. This non-patent literature describes an electrolysis device in which switching between separate and mixed cycles is possible to achieve lower partial loads. Other such alkaline electrolysis devices are known from US 2717872 A. Summary of the Invention

[0005] The purpose of this invention is to provide an alkaline electrolysis device of the type mentioned at the beginning, which has higher efficiency and is safer to operate.

[0006] According to the invention, this objective is achieved in such an alkaline electrolysis apparatus, wherein the alkaline electrolysis apparatus may include at least one electrolytic cell having a reaction chamber for decomposing an aqueous electrolyte into hydrogen and oxygen.

[0007] In addition, it can be specified that the reaction chamber includes a hydrogen-side reaction chamber region containing an aqueous electrolyte, used to decompose the aqueous electrolyte into gaseous hydrogen.

[0008] Additionally, the reaction chamber may include an oxygen-side reaction chamber region containing an aqueous electrolyte for decomposing the aqueous electrolyte into gaseous oxygen.

[0009] In addition, the alkaline electrolysis device may include a hydrogen separator for separating the aqueous electrolyte introduced into the hydrogen separator from the gaseous hydrogen, wherein the hydrogen separator is connected to the hydrogen-side reaction chamber region.

[0010] Furthermore, the alkaline electrolysis device includes an oxygen separator for separating the aqueous electrolyte introduced into the oxygen separator from the gaseous oxygen, wherein the oxygen separator is connected to the oxygen-side reaction chamber region.

[0011] It can also be shown that the hydrogen separator has a first hydrogen separator outlet for discharging an aqueous electrolyte with a first hydrogen concentration and a second hydrogen separator outlet for discharging an aqueous electrolyte with a second hydrogen concentration lower than the first hydrogen concentration.

[0012] The outlets of the first and second hydrogen separators can also preferably be connected to or be connected to the reaction chamber for guiding aqueous electrolytes having a first hydrogen concentration and a second hydrogen concentration back from the hydrogen separators to the reaction chamber.

[0013] An alkaline electrolysis apparatus can be understood in particular as an electrolysis apparatus capable of operating with an alkaline electrolyte or an alkaline solution as the electrolyte. For example, the aqueous electrolyte can be an aqueous solution of potassium hydroxide (also known as a potassium hydroxide solution). Additionally or alternatively, the aqueous electrolyte can be an aqueous solution of sodium hydroxide (also known as a sodium hydroxide solution). Other alkaline aqueous solutions or alkalines based on other metal hydroxides may also be considered in this context.

[0014] The decomposition of aqueous electrolytes into hydrogen and oxygen is preferably understood as the basic principle of water electrolysis, according to which water is decomposed into hydrogen and oxygen by means of an electric current. For this purpose, an alkaline electrolysis device may include at least one electrolytic cell having a reaction chamber. It can be specified that the alkaline electrolysis device may have multiple such electrolytic cells, which are arranged in a stacked configuration, known as a pile. For example, an alkaline electrolysis device may include 2, 3, 4, 5, 6, 7, 8, 9, or 10, or dozens or hundreds of such electrolytic cells, which are then arranged in a stacked configuration to form a pile.

[0015] As described above, the reaction chamber may include a hydrogen-side reaction chamber region and an oxygen-side reaction chamber region, which are separated in a liquid-tight manner by a membrane. This membrane can preferably be configured as an ion-exchange membrane in the form of an ion-permeable polymer membrane. Particularly preferably, the membrane can be configured as an anion-exchange membrane in the form of an anion-permeable polymer membrane. The membrane can be configured to be gas-tight and allow only OH-. - Ions are transported from the hydrogen-side reaction chamber region to the oxygen-side reaction chamber region and vice versa, while preventing the mixing of the generated product gases, namely hydrogen and oxygen, with the electrolyte. The membrane can preferably be constructed of a plastic made of a perfluorinated copolymer. Alternatively or supplementing the membrane, a diaphragm can be provided that liquid-tightly separates the hydrogen-side and oxygen-side reaction chamber regions from each other.

[0016] Furthermore, the hydrogen-side reaction chamber region may have a negative electrode (also known as a cathode) and the oxygen-side reaction chamber region may have a positive electrode (also known as an anode) to generate the cell voltage required for water electrolysis. The cell voltage may, for example, be a DC voltage of at least 1.5 volts.

[0017] Therefore, the oxygen-side reaction chamber region can be the region of the reaction chamber in which gaseous oxygen is generated according to the following reaction formula (1):

[0018] 4OH - -> 2H2O + 4e - + O2 (1).

[0019] Therefore, the hydrogen-side reaction chamber region is the region of the reaction chamber in which gaseous hydrogen is produced according to the following reaction formula (2):

[0020] 4H₂O + 4e - -> 2H2 + 4OH - (2).

[0021] From the two reaction equations above, it can be deduced that water is formed in the aqueous electrolyte (in addition to oxygen) in the oxygen-side reaction chamber region, while water is extracted from the aqueous electrolyte (in the case of hydrogen formation) in the hydrogen-side reaction chamber region. This results in the aforementioned concentration gradient in the aqueous electrolyte, necessitating thorough mixing before the aqueous electrolyte re-enters the reaction chamber.

[0022] After the decomposition of aqueous electrolytes or in OH... -After the ions recombine into gaseous oxygen and hydrogen in the corresponding oxygen-side and hydrogen-side reaction chamber regions, the electrolyte can be introduced into the hydrogen separator and oxygen separator. The hydrogen separator can also be understood as a hydrogen separator device or a component of such a device. Correspondingly, the oxygen separator can also be understood as an oxygen separator device or a component of such a device. The hydrogen separator can preferably be constructed as a gravity- and / or centrifugal force-based separator. Correspondingly, the oxygen separator can also preferably be constructed as a gravity- and / or centrifugal force-based separator.

[0023] In the corresponding oxygen or hydrogen separator, the degree of evolution of gaseous oxygen and hydrogen largely depends on the residence time of the electrolyte within that separator. Correspondingly, in the case of a hydrogen separator, a first hydrogen concentration can be associated with a first residence time, while a second hydrogen concentration can be associated with a second residence time, which is longer than the first residence time. The same applies to the case of an oxygen separator, where a first oxygen concentration can be associated with a first residence time, and a second oxygen concentration can be associated with a second residence time, which is longer than the first residence time.

[0024] Therefore, aqueous electrolytes with a first hydrogen concentration and a second hydrogen concentration can be returned from the hydrogen separator to the reaction chamber. This has the advantage that electrolytes with different hydrogen concentrations can be returned to both the hydrogen-side and oxygen-side reaction chamber regions. Since gaseous hydrogen should be generated in the hydrogen-side reaction chamber region anyway, the return of the electrolyte with the first hydrogen concentration is not critical. Conversely, the hydrogen concentration of the aqueous electrolyte to be returned to the oxygen-side reaction chamber region is critical, because gaseous hydrogen is considered an impurity on the oxygen side and should not exceed the 2% limit (because hydrogen and oxygen form an explosive mixture at a share exceeding 4%).

[0025] Therefore, guiding the return of the electrolyte to a second hydrogen concentration (which is lower than the first hydrogen concentration) can improve the gas purity on the oxygen side, which increases the efficiency of the alkaline electrolysis unit and improves its operational safety. Furthermore, this allows for the advantageous adjustment of the flow rate in the reaction chamber in a manner independent of the degree of mixing, thereby further improving efficiency. The flow rate can thus be adjusted to optimize the temperature and bubble removal in the reaction chamber. Moreover, for example, through improved gas purity, the alkaline electrolysis unit can operate at a lower lower limit partial load (especially when operating at elevated pressures) and / or at a lower alkali concentration (which improves corrosion resistance). A lower lower limit partial load has the advantage of an overall increased load range, which is advantageous, for example, in the case of fluctuating electricity prices and / or fluctuating demand.

[0026] In this regard, it can be stipulated that the outlet of the first hydrogen separator is connected, or can be connected, to the inlet of the hydrogen-side reaction chamber region via a first hydrogen-side electrolyte return guide line, for returning an aqueous electrolyte with a first hydrogen concentration from the hydrogen separator to the hydrogen-side reaction chamber region. This type of return guide from the hydrogen separator is particularly advantageous because the hydrogen-side reaction chamber region is not critical for the electrolyte returning gaseous hydrogen (currently having a first hydrogen concentration greater than the second hydrogen concentration).

[0027] Furthermore, the oxygen separator may have a first oxygen separator outlet for discharging an aqueous electrolyte with a first oxygen concentration, wherein the first oxygen separator outlet may be connected or connectable to the inlet of the oxygen-side reaction chamber region via a first oxygen-side electrolyte return guide line for returning the aqueous electrolyte with the first oxygen concentration from the oxygen separator to the oxygen-side reaction chamber region. Since the oxygen-side reaction chamber region is similarly not critical for the electrolyte returning with gaseous oxygen (currently having a first oxygen concentration greater than a second oxygen concentration), this type of return guide from the oxygen separator is particularly advantageous.

[0028] Furthermore, it can be shown to be beneficial that the outlet of the second hydrogen separator is connected or can be connected to the first oxygen-side electrolyte return guide line via the second hydrogen-side electrolyte return guide line, for the purpose of drawing in and returning an aqueous electrolyte with a second hydrogen concentration from the hydrogen separator to the first oxygen-side electrolyte return guide line.

[0029] As can be seen from the foregoing, the oxygen-side reaction chamber region is critical for the return-guided electrolyte containing gaseous or dissolved hydrogen (currently with a second hydrogen concentration lower than the first oxygen concentration). However, due to the concentration difference between the aqueous electrolytes leaving the hydrogen-side and oxygen-side reaction chamber regions, these electrolyte flows can be equalized by mixing before re-entering these reaction chamber regions. Due to the connectability and / or linkage described above, the electrolyte with the second hydrogen concentration can now be returned-guided to the oxygen-side reaction chamber region (for concentration equalization), which has a favorable impact on efficiency and operational safety, as explained above.

[0030] The first or second hydrogen-side electrolyte return guide line or the first oxygen-side electrolyte return guide line can be understood as a line whose inlet leads to the corresponding outlet of the first or second hydrogen separator or to the outlet of the first oxygen separator. The connection can preferably be understood as a direct flow connection, while connectability can be understood, for example, as a conditional connection (e.g., by means of control and / or regulating valves) or an indirect connection (e.g., by means of a conveying device). The conveying device can, for example, be configured as a conveying pump or include such a conveying pump.

[0031] The oxygen separator may also include a second oxygen separator outlet for discharging an aqueous electrolyte having a second oxygen concentration lower than the first oxygen concentration.

[0032] The second oxygen-side electrolyte return guide line can also be understood as the following line, whose inlet leads to other outlets of the second oxygen separator.

[0033] According to other advantageous design schemes, it is conceivable that the outlet of the second oxygen separator can be connected to, or can be connected to, the first hydrogen side electrolyte return guide line via the second oxygen side electrolyte return guide line, for the purpose of drawing in and returning the aqueous electrolyte with a second oxygen concentration from the oxygen separator to the first hydrogen side electrolyte return guide line.

[0034] The hydrogen-side reaction chamber region can also be critical for the return-guided electrolyte containing gaseous or dissolved oxygen (currently with a second oxygen concentration lower than the first oxygen concentration). As mentioned above, the aqueous electrolyte leaving the hydrogen-side and oxygen-side reaction chamber regions has a concentration gradient of dissolved metal hydroxides (e.g., potassium hydroxide). Therefore, this concentration gradient can advantageously be equalized by mixing before re-entering these reaction chamber regions. Due to the previously described connectability or linkage, the electrolyte with the lower second oxygen concentration can now be returned-guided to the hydrogen-side reaction chamber region (for concentration equalization), which also has a favorable impact on efficiency and operational safety.

[0035] A hydrogen separator may include, for example, a first hydrogen separator unit and a second hydrogen separator unit. The first hydrogen separator unit separates the aqueous electrolyte introduced into the first hydrogen separator unit from the gaseous hydrogen, and the second hydrogen separator unit separates the aqueous electrolyte introduced into the second hydrogen separator unit from the gaseous hydrogen. In other words, a hydrogen separator or hydrogen separator device can be constructed using two sub-units—a first hydrogen separator unit and a second hydrogen separator unit—which allows for more efficient separation of gaseous hydrogen from the aqueous electrolyte.

[0036] Therefore, the first hydrogen separator unit can be configured to separate the aqueous electrolyte from the gaseous hydrogen, such that the aqueous electrolyte can have a first hydrogen concentration due to this separation. It can also be specified that the second hydrogen separator unit is configured to separate the aqueous electrolyte from the gaseous hydrogen, such that the aqueous electrolyte has a second hydrogen concentration due to this separation. The first and / or second hydrogen separator units can preferably operate based on the principle of gravity, according to which the heavier electrolyte in both hydrogen separator units accumulates below the lighter gaseous hydrogen in the direction of gravity, thus causing phase separation. Similarly, alternative principles for hydrogen separation, such as centrifugal separation, can also be used in the first and / or second hydrogen separator units.

[0037] Alternatively, it can be specified that the first hydrogen separator unit has a first hydrogen separator outlet, and the second hydrogen separator unit has a second hydrogen separator outlet. Because the aqueous electrolyte is separated from hydrogen more efficiently through these two separator units, the second oxygen concentration can be further reduced compared to using a single oxygen separator. This can further reduce hydrogen impurities in the oxygen-side reaction chamber region, which can have a more positive impact on efficiency and operational safety.

[0038] A throttling valve can be arranged, for example, between the first and second hydrogen separator units. This throttling valve can reduce the pressure in the second hydrogen separator unit, thereby achieving even better separation.

[0039] A hydrogen-side branch line branches off from the first hydrogen-side electrolyte return guide line and connects to a second hydrogen separator unit for supplying the second hydrogen separator unit with an aqueous electrolyte having a first hydrogen concentration. Preferably, control and / or regulating valves can be arranged in the branch line for controlling and / or regulating the electrolyte mass flow and / or electrolyte volume flow that can be supplied to the second hydrogen separator unit. Therefore, it is advantageous to control and / or regulate the electrolyte mass flow returning to the hydrogen-side reaction chamber region on one hand and the electrolyte mass flow returning to the oxygen-side reaction chamber region on the other (for mixing), thereby further improving efficiency and operational safety. Furthermore, this allows for the implementation of various optional operating strategies for adequately mixing the returned and / or diverted electrolyte mass flows to operate the alkaline electrolysis unit.

[0040] The oxygen separator may also include an oxygen outlet for discharging gaseous oxygen from the oxygen separator, wherein the oxygen outlet is connected or can be connected to a hydrogen separator via an oxygen supply line for supplying gaseous oxygen into the hydrogen separator. By supplying gaseous oxygen into the hydrogen separator, the partial pressure of gaseous hydrogen can be reduced, thereby reducing its solubility on the one hand and increasing its release tendency on the other. Due to the increased electrolyte mass flow, the hydrogen bubble size is reduced (the smaller the bubble size, the more difficult it is to separate from the electrolyte), and thus hydrogen that is more difficult to separate from the aqueous electrolyte can be released in large quantities from the aqueous electrolyte within the hydrogen separator. This can further improve the degree of precipitation between gaseous hydrogen and electrolyte, so that the electrolyte set for thorough mixing has fewer gaseous impurities generated by hydrogen, which is particularly reflected in the improved efficiency and enhanced safety of alkaline electrolysis devices. In addition, the hydrogen concentration in oxygen is more critical because more hydrogen is produced than oxygen (molar ratio of 2:1). Therefore, more hydrogen dissolves in the aqueous electrolyte, which is enhanced by hydrogen diffusion (due to the smaller molecular size) across the membrane.

[0041] In this case, it is advantageous to connect the oxygen outlet to the second hydrogen separator unit via an oxygen supply line to supply gaseous oxygen into the second hydrogen separator unit. As explained above, an aqueous electrolyte with a second hydrogen concentration is used for return guidance and merges into the first oxygen-side electrolyte return guidance line to equalize the electrolyte concentration. Since the hydrogen obtained mainly comes from the first hydrogen separator unit, supplying oxygen into the first hydrogen separator unit would be counterproductive or unsafe, as it would subsequently lead to an explosive mixture. In this regard, supplying oxygen into the second hydrogen separator unit is particularly advantageous because the hydrogen content allowed here is, for example, a maximum of 2%, so that the oxygen share in the gas phase is always at least 98%, thereby preventing the formation of an explosive mixture. Thus, the degree of precipitation during the two-stage separation of hydrogen and aqueous electrolyte can be further improved by the supply of oxygen (additionally, to the improved separation effect of the first and second hydrogen separator units themselves). A maximum of 2% hydrogen is allowed only in the embodiment where the second hydrogen separator unit is connected to the oxygen supply line. However, the supplied oxygen should be separated from the impurity hydrogen on the oxygen side by means of an oxygen purification unit (described below). Without such purification, the effort to supply oxygen cannot be justified for the additional hydrogen evolution in the second hydrogen separator unit. If no oxygen is supplied to the second hydrogen separator unit, at least 98% hydrogen will be present in the gas phase there, thus preventing the possible presence of an explosive mixture.

[0042] An oxygen purification unit can be arranged in the oxygen supply line to remove gaseous hydrogen from gaseous oxygen. The oxygen purification unit may include a polymer membrane with high hydrogen permeability. Alternatively or additionally, the oxygen purification unit may have a microchannel-palladium membrane-oxygen purification unit. Alternatively or additionally, the oxygen purification unit may have a pressure swing adsorption (PSA) oxygen purification unit. Alternatively or additionally, the oxygen purification unit may also operate as a catalytic reaction unit for the catalytic reaction of hydrogen and oxygen to form water. The oxygen purification unit minimizes the hydrogen fraction in the oxygen, allowing for the supply of even purer oxygen to the second hydrogen separator unit, which further improves the separation of gaseous hydrogen from the aqueous electrolyte in the second hydrogen separator unit. Ultimately, the partial pressure of hydrogen can be further reduced by the use of even purer oxygen.

[0043] Alternatively or additionally, the oxygen outlet may be connected, or may be connected, to the oxygen supply inlet of the oxygen separator via an oxygen supply line for returning gaseous oxygen to the oxygen separator. In this case, a portion of the oxygen (containing hydrogen impurities) is purified downstream of the oxygen outlet as described above and returned to the oxygen separator via the oxygen supply inlet, thereby further improving oxygen separation in the electrolyte. This improvement has the additional advantage that the electrolysis unit can operate at an even lower partial load, which increases the overall load range (which is advantageous, for example, under fluctuating electricity prices and / or demand).

[0044] Preferably, an oxygen storage device can be arranged in the oxygen supply line, between the oxygen purification unit and the second hydrogen separator unit. The oxygen storage device can preferably be configured as an oxygen buffer. An oxygen supply valve can also be arranged between the oxygen storage device and the second hydrogen separator unit to control and / or regulate the incoming oxygen. By using the oxygen storage device and / or the oxygen supply valve, the incoming oxygen mass flow can be attenuated, thereby allowing for a more uniform supply to the second hydrogen separator unit, which enables further improved hydrogen evolution from the aqueous electrolyte.

[0045] Furthermore, the oxygen separator may include a first oxygen separator unit and a second oxygen separator unit. The first oxygen separator unit is used to separate the aqueous electrolyte introduced into the first oxygen separator unit from the gaseous oxygen, and the second oxygen separator unit is used to separate the aqueous electrolyte introduced into the second oxygen separator unit from the gaseous oxygen. In other words, the oxygen separator or oxygen separator device can be constructed using two sub-units—first and second oxygen separator units—which allows for more efficient separation of gaseous oxygen and aqueous electrolyte.

[0046] In this regard, it can be specified that the first oxygen separator unit is configured to separate the aqueous electrolyte from the gaseous oxygen, such that the aqueous electrolyte has a first oxygen concentration due to this separation. Furthermore, the second oxygen separator unit is configured to separate the aqueous electrolyte from the gaseous oxygen, such that the aqueous electrolyte has a second oxygen concentration due to this separation. The first and / or second oxygen separator units can preferably operate based on the principle of gravity, according to which the heavier electrolyte in the two oxygen separator units accumulates below the lighter gaseous oxygen in the direction of gravity, thereby causing phase separation. Similarly, alternative principles for oxygen separation, such as centrifugal separation, can be used in the first and / or second hydrogen separator units. The first and / or second oxygen separator units can be constructed as vertical or horizontal oxygen separator units.

[0047] Furthermore, it is conceivable that a first oxygen separator unit has a first oxygen separator outlet, and a second oxygen separator unit has a second oxygen separator outlet. Because oxygen is separated from the aqueous electrolyte more efficiently through these two separator units, the second oxygen concentration can be further reduced compared to using a single oxygen separator. This can further reduce oxygen impurities in the hydrogen-side reaction chamber region, which can have a positive impact on efficiency and operational safety. A throttling valve can be arranged between the first and second oxygen separator units. This throttling valve can reduce the pressure in the second oxygen separator unit, thereby achieving better separation.

[0048] The oxygen-side branch line branches off from the first oxygen-side electrolyte return guide line and connects to the second oxygen separator unit for supplying the second oxygen separator unit with an aqueous electrolyte having a first oxygen concentration. Preferably, additional control and / or regulating valves can be arranged in the branch line for controlling and / or regulating the electrolyte mass flow that can be supplied to the second oxygen separator unit. Therefore, it is advantageous to control and / or regulate the electrolyte mass flow returning to the oxygen-side reaction chamber region on one hand and the electrolyte mass flow returning to the hydrogen-side reaction chamber region on the other (for mixing), thereby further improving efficiency and operational safety. Furthermore, this allows for the implementation of various optional operating strategies for adequately mixing the returned and / or branched electrolyte mass flows to operate the alkaline electrolysis unit.

[0049] According to other preferred designs of the alkaline electrolysis apparatus, it is advantageous to include only a first hydrogen separator unit and a second hydrogen separator unit for two-stage separation of the aqueous electrolyte and gaseous hydrogen, such that an oxygen separator is configured for single-stage separation of the aqueous electrolyte and gaseous oxygen. This configuration achieves a simplified and therefore inexpensive alkaline electrolysis apparatus, because hydrogen impurities on the oxygen side are much more critical than oxygen impurities on the hydrogen side. To address this situation and provide an alkaline electrolysis apparatus with a more inexpensive and simpler construction, it can be advantageous to provide two-stage separation only on the hydrogen side by means of a first hydrogen separator unit and a second hydrogen separator unit. Attached Figure Description

[0050] The following description of preferred embodiments of the invention is intended to provide a detailed explanation of the invention in conjunction with the accompanying drawings. An alkaline electrolytic cell according to the invention is described in the preferred embodiment.

[0051] In the attached diagram:

[0052] Figure 1 A schematic diagram of an alkaline electrolytic cell from the prior art is shown;

[0053] Figure 2 A graph depicting the relationship between the rising speed of a bubble and its size is shown.

[0054] Figure 3 A schematic diagram of a first embodiment of an alkaline electrolysis apparatus according to the present invention is shown;

[0055] Figure 4 A schematic diagram of a second embodiment of the alkaline electrolysis apparatus according to the present invention is shown;

[0056] Figure 5 A schematic diagram of a third embodiment of the alkaline electrolysis apparatus according to the present invention is shown;

[0057] Figure 6A schematic diagram of a fourth embodiment of the alkaline electrolysis apparatus according to the present invention is shown; and

[0058] Figure 7 A schematic diagram of a fifth embodiment of an alkaline electrolysis apparatus according to the present invention is shown. Detailed Implementation

[0059] Figure 1 A schematic diagram of an alkaline electrolysis apparatus 100 from the prior art is shown.

[0060] An alkaline electrolysis apparatus 100 for decomposing an aqueous electrolyte E into hydrogen (H2) and oxygen (O2) includes an electrolytic cell 102 having a reaction chamber 104.

[0061] The reaction chamber 104 includes a hydrogen-side reaction chamber region 106 (containing the aqueous electrolyte E) for decomposing the aqueous electrolyte E into gaseous hydrogen H2. Furthermore, the reaction chamber 104 includes an oxygen-side reaction chamber region 108 (containing the aqueous electrolyte E) for decomposing the aqueous electrolyte E into gaseous oxygen O2. The reaction chamber 104 is a reaction chamber known in the prior art, operating based on the equally known water electrolysis.

[0062] Furthermore, the alkaline electrolysis apparatus 100 includes a hydrogen separator 110 connected to the hydrogen-side reaction chamber region 106 for separating gaseous hydrogen H2 from the aqueous electrolyte E introduced into the hydrogen separator 110. Additionally, the alkaline electrolysis apparatus 100 includes an oxygen separator 112 connected to the oxygen-side reaction chamber region 108 for separating gaseous oxygen O2 from the aqueous electrolyte E introduced into the oxygen separator 112.

[0063] The hydrogen separator 110 also has a hydrogen separator outlet 114 for discharging an aqueous electrolyte E with a hydrogen concentration. This hydrogen concentration should be understood as the residual hydrogen concentration remaining in the aqueous electrolyte E due to incomplete precipitation or separation of hydrogen from the aqueous electrolyte E. Furthermore, the hydrogen separator 110 has a hydrogen outlet 142 for discharging separated gaseous hydrogen, which is then supplied to an external storage device. Figure 1 (not shown in the image) or piping systems for further industrial processing.

[0064] The hydrogen separator outlet 114 can be connected to the reaction chamber 104 via a hydrogen-side return guide line 118, a hydrogen-side return guide conveying device 134, and a mixing unit 136. The return guide conveying device 134 can be configured, for example, as a return guide conveying pump. It is used to return the aqueous electrolyte E having the aforementioned hydrogen concentration from the hydrogen separator 110 to the reaction chamber 104.

[0065] Correspondingly, the oxygen separator 112 also has an oxygen separator outlet 122 for discharging the aqueous electrolyte E with an oxygen concentration. This oxygen concentration should be understood similarly as the residual oxygen concentration remaining in the aqueous electrolyte E due to the incomplete precipitation or separation of oxygen from the aqueous electrolyte E.

[0066] The oxygen separator outlet 122 can be connected to the reaction chamber 104 via an oxygen-side return guide line 124, an oxygen-side return guide conveying device 138, and a mixing unit 136, for returning the aqueous electrolyte E with the aforementioned oxygen concentration from the oxygen separator 112 to the reaction chamber 104. The return guide conveying device 138 can be configured, for example, as a return guide conveying pump or include such a return guide conveying pump.

[0067] According to Figure 1 In the alkaline electrolysis device 100, the chemical half-reactions in the hydrogen-side reaction chamber region 106 and the oxygen-side reaction chamber region 108 result in a concentration gradient in the aqueous electrolyte E.

[0068] Therefore, it is necessary to thoroughly mix the two electrolyte streams (with the aforementioned hydrogen and oxygen concentrations) using the mixing unit 136 to equalize the resulting concentration gradient. Only after this gradient is equalized can one or more thoroughly mixed electrolyte streams be resupplyed to the reaction chamber 104. On the oxygen side, the mixing unit 136 can be bridged via a bypass line 140, thereby allowing the supply of an aqueous electrolyte E with an oxygen concentration to, or the mixing of, an aqueous electrolyte E with a hydrogen concentration to, the aqueous electrolyte E with a hydrogen concentration between the mixing unit 136 and the oxygen-side reaction chamber region 108.

[0069] Figure 2 A graph depicting the relationship between the rising speed of a bubble and its size is shown.

[0070] It can be seen that there is an essentially exponential or polynomial relationship between the rising speed of bubbles in a liquid and the bubble size.

[0071] This relationship is crucial within the framework of this invention because the separated hydrogen H2 in the form of hydrogen bubbles in the hydrogen separator 110 rises in the electrolyte E and leaves the electrolyte E before entering the hydrogen separator 110 (see [link to invention]). Figure 3 (H2) is separated in the form of hydrogen bubbles.

[0072] Therefore, according to Figure 2It can be seen that when electrolyte E enters the hydrogen separator, the bubble size should be as large as possible to minimize the residence time of the electrolyte within the hydrogen separator 110. Secondly, this maximizes the degree to which hydrogen H2 is released or separated from electrolyte E. Because the greater the degree of release, the fewer gaseous impurities in the form of hydrogen H2 supplied to the oxygen-side reaction chamber region 108 via the return guide of electrolyte E, which is particularly reflected in the improved efficiency and enhanced operational safety of the alkaline electrolysis unit 100.

[0073] Figure 3 A schematic diagram of a first embodiment of an alkaline electrolysis apparatus 100 according to the present invention is shown.

[0074] An alkaline electrolysis apparatus 100 for decomposing an aqueous electrolyte E into hydrogen (H2) and oxygen (O2) includes at least one electrolytic cell 102. The aqueous electrolyte E preferably contains 20% to 40% by weight of an aqueous solution of potassium hydroxide (also known as a potassium hydroxide solution). Alternatively or additionally, the aqueous electrolyte E may contain a corresponding aqueous solution of sodium hydroxide (also known as a sodium hydroxide solution). Other alkaline aqueous solutions or alkalis based on other metal hydroxides may also be considered in this context.

[0075] exist Figure 3 An exemplary alkaline electrolysis apparatus 100 with an electrolytic cell 102 is shown. It should be understood that the alkaline electrolysis apparatus 100 may also have multiple such electrolytic cells 102, which may be stacked in a stacked arrangement. For example, the alkaline electrolysis apparatus may include 2, 3, 4, 5, 6, 7, 8, 9, or 10, or dozens or hundreds of such electrolytic cells 102, which are stacked in a stacked arrangement.

[0076] Electrolytic cell 102 includes a reaction chamber 104, which includes a hydrogen-side reaction chamber region 106 containing an aqueous electrolyte E for decomposing the aqueous electrolyte E into gaseous hydrogen H2.

[0077] Correspondingly, the reaction chamber 104 includes an oxygen-side reaction chamber region 108 that contains the aqueous electrolyte E for decomposing the aqueous electrolyte E into gaseous oxygen O2.

[0078] The hydrogen-side reaction chamber region 106 and the oxygen-side reaction chamber region 108 are separated from each other in a liquid-tight manner by an ion-permeable membrane 144. The ion-permeable membrane 144 can preferably be configured as an anion-permeable membrane. The membrane 144 can also be configured to be gas-tight and allow only OH-. - Ions are transported from the hydrogen-side reaction chamber region 106 to the oxygen-side reaction chamber region 108 and vice versa. Simultaneously, this prevents the generated product gases hydrogen (H2) and oxygen (O2) from mixing with the electrolyte E. The membrane 144 can preferably be constructed from a plastic comprising a perfluorinated copolymer.

[0079] On either side of the ion-permeable membrane 144, a negative electrode in the form of a cathode 146 is arranged in the hydrogen-side reaction chamber region 106, and a positive electrode in the form of an anode 148 is arranged in the oxygen-side reaction chamber region 108. The cathode 146 and anode 148 are preferably in direct contact with the ion-permeable membrane 144, and generate the necessary DC voltage of at least 1.5 volts.

[0080] Oxygen-side reaction chamber region 108 is a closed region of reaction chamber 104, in which gaseous oxygen O2 is generated according to the following reaction formula (1):

[0081] 4OH - -> 2H2O + 4e - + O2 (1).

[0082] The hydrogen-side reaction chamber region 106 is therefore a closed region of reaction chamber 104, in which gaseous hydrogen is produced according to the following reaction formula (2):

[0083] 4H₂O + 4e - -> 2H2 + 4OH - (2).

[0084] The hydrogen-side reaction chamber region 106 also has an inlet 120 and an outlet 150 for supplying and discharging the aqueous electrolyte E, and correspondingly, the oxygen-side reaction chamber region 108 also has an inlet 126 and an outlet 152 for supplying and discharging the aqueous electrolyte E.

[0085] The alkaline electrolysis unit 100 also includes a hydrogen separator 110, which is connected via an outlet 150 to the hydrogen-side reaction chamber region 106 for separating gaseous hydrogen H2 from the aqueous electrolyte E introduced into the hydrogen separator 110. This connection is made via a hydrogen-side electrolyte supply line 164.

[0086] according to Figure 3 The hydrogen separator 110 is preferably configured as a gravity separator for two-stage gas separation, and is horizontally oriented in its assembled state. Liquid aqueous electrolyte E accumulates therein on the bottom side, thus forming a bottom-side electrolyte volume. In the gravitational direction, a gaseous volume of hydrogen H2 accumulates above the liquid electrolyte E; this hydrogen is first contained in the liquid electrolyte E as bubbles and then released from it. Since the liquid aqueous electrolyte E has a higher density than gaseous hydrogen H2, separation occurs between the liquid electrolyte phase and the gaseous hydrogen phase.

[0087] The hydrogen separator 110 also has a first hydrogen separator outlet 114 for discharging an aqueous electrolyte E having a first hydrogen concentration. The aqueous electrolyte E having the first hydrogen concentration is generated by the incomplete separation of hydrogen H2 and aqueous electrolyte E from the hydrogen separator 110 via the first hydrogen separator outlet 114 after a first residence time t1.

[0088] As in Figure 3 As can be seen, hydrogen separator 110 has a second hydrogen separator outlet 116 for discharging an aqueous electrolyte E with a second hydrogen concentration lower than the first hydrogen concentration. Similarly, an aqueous electrolyte E with a second hydrogen concentration is generated by the incomplete separation of hydrogen H2 and aqueous electrolyte E from hydrogen separator 110 via the second hydrogen separator outlet 116 after a second residence time t2. Due to the longer residence time t2 compared to t1, according to Figure 2 The relationship shown indicates that a larger amount of bubbles can be released from the aqueous electrolyte E, resulting in a second hydrogen concentration that is less than the first hydrogen concentration.

[0089] The hydrogen separator 110 also has separating elements 154 and 156 for additional mechanical separation of the liquid electrolyte phase and the gaseous hydrogen phase. These separating elements may be placed in the hydrogen separator 110 in the form of perforated plates or other preferably porous packings.

[0090] Alternatively, in a design scheme that replaces a horizontal separator, the hydrogen separator 110 may be configured as a gravity separator, oriented vertically in its assembled state. Alternatively, the hydrogen separator 110 may be configured as a centrifugal separator.

[0091] The first hydrogen separator outlet 114 and the second hydrogen separator outlet 116 can be connected to the reaction chamber 104 for returning aqueous electrolyte E with a first hydrogen concentration and a second hydrogen concentration from the hydrogen separator 110 to the reaction chamber 104.

[0092] For this purpose, the alkaline electrolysis apparatus 100 includes a first hydrogen-side electrolyte return guide line 118, by means of which the outlet 114 of the first hydrogen separator can be connected to the inlet 120 of the hydrogen-side reaction chamber region 106 for returning and guiding an aqueous electrolyte E with a first hydrogen concentration from the hydrogen separator 110 to the hydrogen-side reaction chamber region 106.

[0093] A hydrogen-side return guide pump 134 is arranged in the first hydrogen-side electrolyte return guide line 118, which supplies an aqueous electrolyte E with a first hydrogen concentration to the inlet 120 of the hydrogen-side reaction chamber region 106. Since the decomposition of the aqueous electrolyte E into hydrogen H2 occurs anyway in the hydrogen-side reaction chamber region 106, the return guide of the electrolyte E with a high first hydrogen concentration is not critical.

[0094] In addition, the hydrogen separator 110 has a hydrogen outlet 142 for discharging separated gaseous hydrogen, which can then be supplied to an external storage device. Figure 1 (not shown in the image) or piping systems for further industrial processing.

[0095] Furthermore, the alkaline electrolysis apparatus 100 includes an oxygen separator 112 connected to the oxygen-side reaction chamber region 108 for separating the aqueous electrolyte E introduced into the oxygen separator 112 from gaseous oxygen O2. This connection is achieved via an oxygen-side electrolyte supply line 166.

[0096] according to Figure 3 The oxygen separator 112 is preferably configured as a gravity separator for two-stage separation, and is horizontally oriented in its assembled state. Liquid aqueous electrolyte E accumulates therein on the bottom side, thus forming the electrolyte volume on the bottom side. In the gravitational direction, a gaseous volume of oxygen O2 accumulates above the liquid electrolyte E; this oxygen is first contained in the liquid electrolyte E in the form of bubbles and then released from it. Since the liquid aqueous electrolyte E has a higher density than gaseous oxygen O2, separation occurs between the liquid electrolyte phase and the gaseous oxygen phase.

[0097] The oxygen separator 112 also has a first oxygen separator outlet 122 for discharging an aqueous electrolyte E having a first oxygen concentration. The aqueous electrolyte E having a first oxygen concentration is generated by the incomplete separation of oxygen O2 and aqueous electrolyte E discharged from the oxygen separator 112 via the first oxygen separator outlet 122 after a first residence time t1.

[0098] As in Figure 3 As can be seen, oxygen separator 112 has a second oxygen separator outlet 130 for discharging aqueous electrolyte E with a second oxygen concentration lower than the first oxygen concentration. Similarly, aqueous electrolyte E with a second oxygen concentration is generated by the incomplete separation of oxygen O2 from aqueous electrolyte E through the second oxygen separator outlet 130 after a second residence time t2. Due to the longer residence time t2 compared to t1, according to Figure 2 The relationship shown indicates that a larger amount of bubbles can be released from the aqueous electrolyte E, resulting in a second oxygen concentration that is less than the first oxygen concentration.

[0099] The oxygen separator 112 also has separating elements 158 and 160 for additional mechanical separation of the liquid electrolyte phase and the gaseous oxygen phase. These separating elements may be placed in the oxygen separator 112 in the form of perforated plates or other preferably porous packings.

[0100] Alternatively, in a design scheme that replaces a horizontal separator, the oxygen separator 112 may be configured as a gravity separator, oriented vertically in its assembled state. Alternatively, the oxygen separator 112 may be configured as a centrifugal separator.

[0101] The first oxygen separator outlet 122 and the second oxygen separator outlet 130 can be connected to the reaction chamber 104 for returning aqueous electrolyte E with a first oxygen concentration and a second oxygen concentration from the oxygen separator 112 to the reaction chamber 104.

[0102] For this purpose, the alkaline electrolysis device 100 includes a first oxygen-side electrolyte return guide line 124, by means of which the outlet 122 of the first oxygen separator can be connected to the inlet 126 of the oxygen-side reaction chamber region 108 for returning and guiding an aqueous electrolyte E with a first oxygen concentration from the oxygen separator 112 into the oxygen-side reaction chamber region 108.

[0103] An oxygen-side return guide pump 138 is arranged in the first oxygen-side electrolyte return guide line 124, which supplies an aqueous electrolyte E with a first oxygen concentration to the inlet 126 of the oxygen-side reaction chamber region 108. Since the decomposition of the aqueous electrolyte E into oxygen (O2) occurs anyway in the oxygen-side reaction chamber region 108, the return guide of the electrolyte E with a high first oxygen concentration is not critical. Instead, the hydrogen concentration is critical, as it is included in the aqueous electrolyte E supplied to the oxygen-side reaction chamber region 108 due to necessary adequate mixing (see the discussion above).

[0104] In addition, the oxygen separator 112 has an oxygen outlet 162 for discharging separated gaseous oxygen, which can then typically be supplied to the atmosphere.

[0105] according to Figure 3 The alkaline electrolysis unit 100 also includes a second hydrogen-side electrolyte return guide line 128, through which the second hydrogen separator outlet 116 is connected to a first oxygen-side electrolyte return guide line 124. This second hydrogen-side electrolyte return guide line 128 is used to draw in and return an aqueous electrolyte E with a second hydrogen concentration from the hydrogen separator 110 to the first oxygen-side electrolyte return guide line 124. Therefore, a well-mixed electrolyte E is supplied to the oxygen-side reaction chamber region 108, which has only a low second hydrogen concentration (except for the non-critical first oxygen concentration). This reduces gaseous impurities in the oxygen-side reaction chamber region 108 due to hydrogen (H2), thereby improving efficiency and operational safety.

[0106] In the opposite case, oxygen concentration is critical, as it is contained in the electrolyte E supplied to the hydrogen-side reaction chamber region due to the necessary adequate mixing (see the discussion above).

[0107] In this regard, the alkaline electrolysis unit 100 has a second oxygen-side electrolyte return guide line 132, through which the outlet 130 of the second oxygen separator is connected to a first hydrogen-side electrolyte return guide line 118 for receiving and returning an aqueous electrolyte E with a second oxygen concentration from the oxygen separator 112 to the first hydrogen-side electrolyte return guide line 118. Thus, a well-mixed electrolyte E is supplied to the hydrogen-side reaction chamber region 106, which has only a low second oxygen concentration (except for the non-critical first hydrogen concentration). This reduces gaseous impurities in the hydrogen-side reaction chamber region 106 by a smaller proportion of oxygen (O2), thereby improving efficiency and operational safety.

[0108] exist Figure 3 Each of the pipes 118, 124, 128, 132, 164, and 166 shown is provided with a control valve and / or regulating valve 168, by means of which the electrolyte flow in these pipes 118, 124, 128, 132, 164, and 166 can be controlled and / or regulated accordingly. For this purpose, the control valve and / or regulating valve 168 is connected to a control unit and / or regulating unit 172 via a signal line 170. The signal line 170 and the control unit and / or regulating unit 172 are described below. Figures 4 to 6 Not shown, but still included in these embodiments of the alkaline electrolysis apparatus 200, 300 and 400 according to the invention.

[0109] Figure 4 A schematic diagram of a second embodiment of the alkaline electrolysis apparatus 200 according to the present invention is shown.

[0110] The second embodiment of the alkaline electrolysis apparatus 200 according to the present invention is structurally and functionally based on the alkaline electrolysis apparatus 100 according to the present invention. Figure 3 The first embodiment, wherein the differences in structure and function are explained below:

[0111] Hydrogen separator 210 is not as Figure 3 Instead of being designed as a single unit with two stages of hydrogen separation, the hydrogen separator 210 has a separate unit for each separation stage. Accordingly, the hydrogen separator 210 includes a first hydrogen separator unit 214 and a second hydrogen separator unit 216. The first hydrogen separator unit 214 separates the aqueous electrolyte E introduced into the first hydrogen separator unit 214 from gaseous hydrogen H2, and the second hydrogen separator unit 216 separates the aqueous electrolyte E introduced into the second hydrogen separator unit 216 from gaseous hydrogen H2.

[0112] according to Figure 4The first hydrogen separator unit 214 is preferably configured as a gravity separator unit for single-stage separation, and is horizontally oriented in its assembled state. Liquid aqueous electrolyte E accumulates therein on the bottom side, thus forming the electrolyte volume on the bottom side. In the gravitational direction, a gaseous volume of hydrogen H2 accumulates above the liquid electrolyte E, which is first contained in the liquid electrolyte E as bubbles and then released from it. Since the liquid aqueous electrolyte E has a higher density than gaseous hydrogen H2, separation occurs between the liquid electrolyte phase and the gaseous hydrogen phase.

[0113] The first hydrogen separator unit 214 also has one or more separating elements 154, 156 for additional mechanical separation of the liquid electrolyte phase and the gaseous hydrogen phase. These separating elements may be placed in the hydrogen separator unit 214 in the form of perforated plates or other preferably porous packing materials.

[0114] Alternatively, in a design scheme for a horizontal separator unit, the hydrogen separator unit 214 may be configured as a gravity separator unit, oriented vertically in its assembled state. Alternatively, the hydrogen separator unit 214 may be configured as a centrifugal separator unit.

[0115] The second hydrogen separator unit 216 is configured in structure and function to correspond to the first hydrogen separator unit 214.

[0116] according to Figure 4 The first hydrogen separator unit 214 has a first hydrogen separator outlet 114, and the second hydrogen separator unit 216 correspondingly has a second hydrogen separator outlet 116.

[0117] The hydrogen-side branch line 218 branches off from the first hydrogen-side electrolyte return guide line 118 and is connected to or can be connected to the second hydrogen separator unit 216 for supplying the second hydrogen separator unit 216 with an aqueous electrolyte E having a first hydrogen concentration.

[0118] Therefore, the first hydrogen separator unit 214 is configured to separate gaseous hydrogen H2 from the aqueous electrolyte E, such that the aqueous electrolyte E has a first hydrogen concentration due to this separation. Correspondingly, the second hydrogen separator unit 216 is configured to separate gaseous hydrogen H2 from the aqueous electrolyte E, such that the aqueous electrolyte E has a second hydrogen concentration due to this separation.

[0119] Conversely, oxygen separator 212 is configured as a single-stage oxygen separator and correspondingly has only a first oxygen separator outlet 122, which can be connected to the inlet 126 of the oxygen-side reaction chamber region 108 via a first oxygen-side electrolyte return guide line 124. This enables the return guide of an aqueous electrolyte E with a first oxygen concentration from oxygen separator 212 into the oxygen-side reaction chamber region 108.

[0120] Alternatively, oxygen separator 212 can be designed as a two-stage ( Figure 4 (not shown in the figure), which allows it to have a separate oxygen separation unit for each separation stage.

[0121] The first oxygen separator unit may have a first oxygen separator outlet 122, wherein the first oxygen-side electrolyte return guide line 124 may be connected to the first oxygen separator outlet 122 through its inlet.

[0122] In addition, the second oxygen separator unit may have a second oxygen separator outlet 130 (see Figure 6 The second oxygen-side electrolyte return guide line 132 is connected to the outlet 130 of the second oxygen separator through its inlet.

[0123] Therefore, the first oxygen separator unit is configured to separate gaseous oxygen O2 from the aqueous electrolyte E, such that the aqueous electrolyte E has a first oxygen concentration due to this separation, and is then returned to the oxygen-side reaction chamber region 108. Correspondingly, the second oxygen separator unit can be configured to separate gaseous oxygen O2 from the aqueous electrolyte E, such that the aqueous electrolyte E has a second oxygen concentration due to this separation, and is then returned to the hydrogen-side reaction chamber region 106.

[0124] Additionally, a connection line 220 with an integrated control and / or regulating valve 168 may extend between the first oxygen-side electrolyte return guide line 124 and the first hydrogen-side electrolyte return guide line 118. This line 220 is used to channel electrolyte E with a first oxygen concentration into the first hydrogen-side electrolyte return guide line 118, thereby guiding the return of electrolyte E with a first hydrogen concentration. Since the oxygen concentration on the hydrogen side is less critical than in other cases, this type of thorough mixing can be achieved accordingly with the first (i.e., larger) hydrogen and oxygen concentrations on the hydrogen side.

[0125] Therefore, only the hydrogen separator 210 includes a first hydrogen separator unit 214 and a second hydrogen separator unit 216 for two-stage separation of gaseous hydrogen H2 and aqueous electrolyte E, while the oxygen separator 212 is configured to separate gaseous oxygen O2 and aqueous electrolyte E in a single stage.

[0126] Figure 5 A schematic diagram of a third embodiment of the alkaline electrolysis apparatus 300 according to the present invention is shown.

[0127] The third embodiment of the alkaline electrolysis apparatus 300 according to the present invention is based in structure and function on the alkaline electrolysis apparatus 200 according to the present invention. Figure 4 The second embodiment, wherein the differences in structure and function are explained below:

[0128] The oxygen separator 212 is configured as a single-stage oxygen separator and has an oxygen outlet 302 for discharging gaseous oxygen O2 from the oxygen separator 212.

[0129] Alternatively, oxygen separator 212 can be designed as a two-stage ( Figure 5 (not shown in the figure), which allows it to have a separate oxygen separation unit for each separation stage.

[0130] The first oxygen separator unit may have a first oxygen separator outlet 122, wherein the first oxygen-side electrolyte return guide line 124 may be connected to the first oxygen separator outlet 122 through its inlet.

[0131] In addition, the second oxygen separator unit may have a second oxygen separator outlet 130 (see Figure 6 The second oxygen-side electrolyte return guide line 132 is connected to the outlet 130 of the second oxygen separator through its inlet.

[0132] Therefore, the first oxygen separator unit is configured to separate gaseous oxygen O2 from the aqueous electrolyte E, such that the aqueous electrolyte E has a first oxygen concentration due to this separation, and is then returned to the oxygen-side reaction chamber region 108. Correspondingly, the second oxygen separator unit can be configured to separate gaseous oxygen O2 from the aqueous electrolyte E, such that the aqueous electrolyte E has a second oxygen concentration due to this separation, and is then returned to the hydrogen-side reaction chamber region 106.

[0133] according to Figure 5 The oxygen outlet 302 can be connected to the hydrogen separator 210 via the oxygen supply line 304 to supply gaseous oxygen (O2) into the hydrogen separator 210. Specifically, the oxygen outlet 302 is connected to the second hydrogen separator unit 216 via the oxygen supply line 304 to supply gaseous oxygen (O2) into the second hydrogen separator unit 216. For this purpose, the second hydrogen separator unit 216 has an oxygen supply inlet 310, into which the oxygen supply line 304 leads.

[0134] As previously described, the aqueous electrolyte E with a second hydrogen concentration is used for return guidance and flows into the first oxygen-side electrolyte return guidance line 124 for thorough mixing of electrolyte E. Since the obtained hydrogen primarily originates from the first hydrogen separator unit 214, supplying it to this unit would be counterproductive or unsafe, as it would subsequently lead to an explosive mixture. In this regard, supplying it to the second hydrogen separator unit 216 is particularly advantageous, as the maximum permissible hydrogen content here is 2%, ensuring that the oxygen content in the gas phase is always at least 98%. Therefore, no explosive mixture is formed. Thus, the degree of precipitation during the two-stage separation of aqueous electrolyte E and hydrogen H2 can be further enhanced by the supply of oxygen (in addition to the improved separation effect of the first hydrogen separator unit 214 and the second hydrogen separator unit 216). Ultimately, the hydrogen partial pressure can be further reduced due to the presence of oxygen O2, resulting in even better hydrogen separation in the second hydrogen separator unit 216.

[0135] according to Figure 5 An oxygen purification unit 306 is arranged in the oxygen supply pipeline 304 to remove gaseous hydrogen H2 from gaseous oxygen O2.

[0136] Oxygen purification unit 304 may include a polymer membrane with high hydrogen permeability. Alternatively or additionally, oxygen purification unit 304 may have a microchannel-palladium membrane-oxygen purification unit. Alternatively or additionally, oxygen purification unit 304 may have a pressure swing adsorption-oxygen purification unit. Alternatively or additionally, oxygen purification unit 304 may have a catalytic reaction unit for the catalytic reaction of hydrogen and oxygen to form water.

[0137] Optionally, an oxygen buffer 308 can be arranged in the oxygen supply line 304, positioned between the oxygen purification unit 306 and the second hydrogen separator unit 216. With the aid of the oxygen buffer 308, the mass flow of oxygen entering the second hydrogen separator unit 216 can be reduced, allowing for a more uniform supply, resulting in further improved hydrogen evolution from the aqueous electrolyte E.

[0138] Figure 6 A schematic diagram of a fourth embodiment of the alkaline electrolysis apparatus 400 according to the present invention is shown.

[0139] The fourth embodiment of the alkaline electrolysis apparatus 400 according to the present invention is based in structure and function on the alkaline electrolysis apparatus 100 according to the present invention. Figure 3 The first embodiment, wherein the differences in structure and function are explained below:

[0140] The hydrogen separator 210 is structurally and functionally similar to the alkaline electrolysis apparatus 200 according to the invention. Figure 4 It is constructed as in the second embodiment.

[0141] Conversely, oxygen separator 402 is not like... Figure 3 Instead of being designed as a single unit with two-stage oxygen separation, it has a separate unit for each separation stage. Accordingly, oxygen separator 402 includes a first oxygen separator unit 404 and a second oxygen separator unit 406. The first oxygen separator unit 404 is used to separate the aqueous electrolyte E introduced into the first oxygen separator unit 404 from gaseous oxygen O2, and the second oxygen separator unit 406 is used to separate the aqueous electrolyte E introduced into the second oxygen separator unit 406 from gaseous oxygen O2.

[0142] according to Figure 6 The first oxygen separator unit 404 is preferably configured as a gravity separator unit for single-stage separation, and is horizontally oriented in its assembled state. Liquid aqueous electrolyte E accumulates therein on the bottom side, thus forming the electrolyte volume on the bottom side. In the gravitational direction, a gaseous volume of oxygen O2 accumulates above the liquid electrolyte E, which is first contained in the liquid electrolyte E in the form of bubbles and then released from it. Since the liquid aqueous electrolyte E has a higher density than gaseous oxygen O2, separation occurs between the liquid electrolyte phase and the gaseous oxygen phase.

[0143] The first oxygen separator unit 404 also has one or more separating elements 154, 156 for additional mechanical separation of the liquid electrolyte phase and the gaseous oxygen phase. These separating elements may be placed in the oxygen separator unit 404 in the form of perforated plates or other preferably porous packing materials.

[0144] Alternatively, in a design scheme for a horizontal separator unit, the first oxygen separator unit 404 may be configured as a gravity separator unit, oriented vertically in its assembled state. Alternatively, the first oxygen separator unit 404 may be configured as a centrifugal separator unit.

[0145] The second oxygen separator unit 406 is configured in structure and function to correspond to the first oxygen separator unit 404.

[0146] according to Figure 6 The first oxygen separator unit 404 has a first oxygen separator outlet 122, and the second oxygen separator unit 406 correspondingly has a second oxygen separator outlet 130.

[0147] The oxygen-side branch line 408 branches off from the first oxygen-side electrolyte return guide line 124 and is connected to or can be connected to the second oxygen separator unit 406 for supplying the second oxygen separator unit 406 with an aqueous electrolyte E having a first oxygen concentration.

[0148] Therefore, the first oxygen separator unit 404 is configured to separate gaseous oxygen O2 from the aqueous electrolyte E, such that the aqueous electrolyte E has a first oxygen concentration due to this separation. Correspondingly, the second oxygen separator unit 406 is configured to separate gaseous oxygen O2 from the aqueous electrolyte E, such that the aqueous electrolyte E has a second oxygen concentration due to this separation.

[0149] Figure 7 A schematic diagram of a fifth embodiment of the alkaline electrolysis apparatus 500 according to the present invention is shown.

[0150] The fifth embodiment of the alkaline electrolysis apparatus 500 according to the present invention is structurally and functionally based on the alkaline electrolysis apparatus 300 according to the present invention. Figure 5 The third embodiment, wherein the differences in structure and function are explained below:

[0151] According to the alkaline electrolysis apparatus 300 of the present invention Figure 5 Compared to the third embodiment, the oxygen separator 212 itself is not the second hydrogen separator unit 216 that has the oxygen supply inlet 310.

[0152] Therefore, oxygen outlet 302 can be connected to oxygen supply inlet 310 via oxygen supply line 304 to return a portion of gaseous oxygen O2 to oxygen separator 212.

[0153] according to Figure 7 An oxygen purification unit 306 is arranged in the oxygen supply pipeline 304 to remove gaseous hydrogen H2 from gaseous oxygen O2.

[0154] Oxygen purification unit 304 may include a polymer membrane with high hydrogen permeability. Alternatively or additionally, oxygen purification unit 304 may have a microchannel-palladium membrane-oxygen purification unit. Alternatively or additionally, oxygen purification unit 304 may have a pressure swing adsorption-oxygen purification unit. Alternatively or additionally, oxygen purification unit 304 may have a catalytic reaction unit for the catalytic reaction of hydrogen and oxygen to form water.

[0155] The degree of precipitation in oxygen separator 212 can be further improved by using purified oxygen (O2). Finally, the oxygen partial pressure can be further reduced by the absence or near absence of hydrogen (H2), resulting in even better oxygen separation in oxygen separator 212.

[0156] In the oxygen supply line 304, an oxygen delivery device 312 is further arranged between the oxygen purification unit 306 and the oxygen outlet 302. The oxygen delivery device 312 may be, for example, an oxygen supply compressor. Optionally, a control and / or regulating valve 168 may also be arranged in the oxygen supply line 304 between the oxygen purification unit 306 and the oxygen supply inlet 310.

[0157] In particular, the oxygen delivery device 312 and the control and / or regulating valve 168 can control or regulate a portion of the mass flow and / or volume flow of oxygen returned from the oxygen outlet 302 to guide and purify it.

[0158] Explanation of reference numerals in the attached figures

[0159] 100 Electrolysis Unit

[0160] 102 Electrolytic Cell

[0161] 104 reaction chamber

[0162] 106 Hydrogen-side reaction chamber region

[0163] 108 Oxygen-side reaction chamber area

[0164] 110 Hydrogen Separator

[0165] 112 Oxygen Separator

[0166] 114 First Hydrogen Separator Outlet

[0167] 116 Second Hydrogen Separator Outlet

[0168] 118 First hydrogen-side electrolyte return guide line

[0169] Entrance to the 120 hydrogen-side reaction chamber area

[0170] 122 First Oxygen Separator Outlet

[0171] 124 First oxygen-side electrolyte return guide line

[0172] Entrance to the oxygen-side reaction chamber area 126

[0173] 128 Second hydrogen side electrolyte return guide line

[0174] 130 Second Oxygen Separator Outlet

[0175] 132 Second oxygen-side electrolyte return guide line

[0176] 134 Hydrogen-side return guide and conveyor device

[0177] 136 hybrid unit

[0178] 138 Oxygen Side Return Guiding Conveyor

[0179] 140 bypass pipeline

[0180] 142 hydrogen outlet

[0181] 144 ion-permeable membrane

[0182] 146 cathode

[0183] 148 anode

[0184] The outlet of the 150 hydrogen-side reaction chamber area

[0185] The outlet of the oxygen-side reaction chamber area 152

[0186] 154 separate components

[0187] 156 separate components

[0188] 158 separate components

[0189] 160 separate components

[0190] 162 Oxygen Outlet

[0191] 164 Hydrogen-side electrolyte supply pipeline

[0192] 166 Oxygen-side electrolyte supply pipeline

[0193] 168 Control and / or regulating valves

[0194] 170 signal line

[0195] 172 Control and / or regulating device

[0196] 200 Electrolysis Unit

[0197] 210 Hydrogen Separator

[0198] 212 Oxygen Separator

[0199] 214 First Hydrogen Separator Unit

[0200] 216 Second Hydrogen Separator Unit

[0201] 218 Hydrogen-side branch pipeline

[0202] 220 connecting pipe

[0203] 300 Electrolysis Unit

[0204] 302 Oxygen Outlet

[0205] 304 oxygen supply pipeline

[0206] 306 Oxygen Purification Unit

[0207] 308 Oxygen Storage

[0208] 310 Oxygen Supply Inlet

[0209] 312 Oxygen Delivery Unit

[0210] 400 Electrolysis Unit

[0211] 402 Oxygen Separator

[0212] 404 First Oxygen Separator Unit

[0213] 406 Second Oxygen Separator Unit

[0214] 408 Oxygen-side branch piping

[0215] 500 Electrolysis Unit

[0216] E contains aqueous electrolytes

[0217] H2 hydrogen

[0218] O2 oxygen

Claims

1. An alkaline electrolysis apparatus (100; 200; 300; 400; 500) for decomposing an aqueous electrolyte (E) into hydrogen (H2) and oxygen (O2), said alkaline electrolysis apparatus comprising: - At least one electrolytic cell (102) including a reaction chamber (104) comprising a hydrogen-side reaction chamber region (106) for containing the aqueous electrolyte (E) and for decomposing the aqueous electrolyte (E) into gaseous hydrogen (H2), and comprising an oxygen-side reaction chamber region (108) for containing the aqueous electrolyte (E) and for decomposing the aqueous electrolyte (E) into gaseous oxygen (O2). - A hydrogen separator (110; 210) for separating the aqueous electrolyte (E) introduced into the hydrogen separator (110; 210) from the gaseous hydrogen (H2), wherein the hydrogen separator (110; 210) is connected to the hydrogen-side reaction chamber region (106); and - An oxygen separator (112; 212; 402) for separating the aqueous electrolyte (E) introduced into the oxygen separator (112; 212; 402) from the gaseous oxygen (O2), wherein the oxygen separator (112; 212; 402) is connected to the oxygen-side reaction chamber region (108); wherein The hydrogen separator (110; 210) has a first hydrogen separator outlet (114) for discharging the aqueous electrolyte (E) having a first hydrogen concentration and a second hydrogen separator outlet (116) for discharging the aqueous electrolyte (E) having a second hydrogen concentration lower than the first hydrogen concentration; and wherein The first hydrogen separator outlet (114) and the second hydrogen separator outlet (116) are connected to or can be connected to the reaction chamber (104) for returning the aqueous electrolyte (E) having the first hydrogen concentration and the second hydrogen concentration from the hydrogen separator (110; 210) to the reaction chamber (104).

2. The alkaline electrolysis device (100; 200; 300; 400; 500) according to claim 1, characterized in that, The outlet (114) of the first hydrogen separator is connected or can be connected to the inlet (120) of the hydrogen-side reaction chamber region (106) via a first hydrogen-side electrolyte return guide line (118) for returning the aqueous electrolyte (E) having the first hydrogen concentration from the hydrogen separator (110; 210) to the hydrogen-side reaction chamber region (106); The oxygen separator (112; 212; 402) has a first oxygen separator outlet (122) for discharging the aqueous electrolyte (E) having a first oxygen concentration, wherein the first oxygen separator outlet (122) is connected or can be connected to the inlet (126) of the oxygen-side reaction chamber region (108) via a first oxygen-side electrolyte return guide line (124) for returning the aqueous electrolyte (E) having the first oxygen concentration from the oxygen separator (112; 212, 402) to the oxygen-side reaction chamber region (108); and The second hydrogen separator outlet (116) is connected or can be connected to the first oxygen side electrolyte return guide line (124) via the second hydrogen side electrolyte return guide line (128) for receiving and returning the aqueous electrolyte (E) having the second hydrogen concentration from the hydrogen separator (110; 210) to the first oxygen side electrolyte return guide line (124).

3. The alkaline electrolysis device (100; 200; 300; 400; 500) according to claim 2, characterized in that, The oxygen separator (112; 402) has a second oxygen separator outlet (130) for discharging the aqueous electrolyte (E) having a second oxygen concentration lower than the first oxygen concentration, wherein The second oxygen separator outlet (130) is connected or can be connected to the first hydrogen side electrolyte return guide line (118) via the second oxygen side electrolyte return guide line (132) for receiving and returning the aqueous electrolyte (E) with the second oxygen concentration from the oxygen separator (112; 402) to the first hydrogen side electrolyte return guide line (118).

4. The alkaline electrolysis apparatus (200; 300; 400; 500) according to any one of the preceding claims, characterized in that, The hydrogen separator (210) includes a first hydrogen separator unit (214) and a second hydrogen separator unit (216), wherein the first hydrogen separator unit is used to separate the aqueous electrolyte (E) introduced into the first hydrogen separator unit (214) from the gaseous hydrogen (H2), and the second hydrogen separator unit is used to separate the aqueous electrolyte (E) introduced into the second hydrogen separator unit (216) from the gaseous hydrogen (H2).

5. The alkaline electrolysis device (200; 300; 400; 500) according to claim 4, characterized in that, The first hydrogen separator unit (214) is configured to separate the aqueous electrolyte (E) from gaseous hydrogen (H2), such that the aqueous electrolyte (E) has a first hydrogen concentration due to the separation; and The second hydrogen separator unit (216) is configured to separate the aqueous electrolyte (E) from gaseous hydrogen (H2) such that the aqueous electrolyte (E) has a second hydrogen concentration due to the separation.

6. The alkaline electrolysis apparatus (200; 300; 400; 500) according to claim 4 or 5, characterized in that, The first hydrogen separator unit (214) has a first hydrogen separator outlet (114), and the second hydrogen separator unit (216) has a second hydrogen separator outlet (116).

7. The alkaline electrolysis apparatus (200; 300; 400; 500) according to any one of claims 4 to 6, characterized in that, A hydrogen-side branch line (218) branches off from the first hydrogen-side electrolyte return guide line (118) and is connected to the second hydrogen separator unit (216) for supplying the aqueous electrolyte (E) having a first hydrogen concentration to the second hydrogen separator unit (216).

8. The alkaline electrolysis apparatus (300; 500) according to any one of the preceding claims, characterized in that, The oxygen separator (212) has an oxygen outlet (302) for discharging gaseous oxygen (O2) from the oxygen separator (212), wherein the oxygen outlet (302) is connected to the oxygen supply line (304) via: - The hydrogen separator (210) is connected or can be connected for supplying the gaseous oxygen (O2) into the hydrogen separator (210), and / or - The oxygen supply inlet (310) of the oxygen separator (212) is connected or can be connected to return the gaseous oxygen (O2) into the oxygen separator (212).

9. The alkaline electrolysis apparatus (300) according to claim 8, characterized in that, The oxygen outlet (302) is connected to the second hydrogen separator unit (216) via the oxygen supply pipeline (304) to supply gaseous oxygen (O2) into the second hydrogen separator unit (216).

10. The alkaline electrolysis apparatus (300) according to claim 8 or 9, characterized in that, An oxygen purification unit (306) is arranged in the oxygen supply line (304) for removing gaseous hydrogen (H2) from the gaseous oxygen, wherein Preferably, an oxygen storage device (308) or a preferred oxygen buffer storage device is arranged in the oxygen supply line (304), and the oxygen storage device is arranged between the oxygen purification unit (306) and the second hydrogen separator unit (216).

11. The alkaline electrolysis apparatus (400) according to any one of the preceding claims, characterized in that, The oxygen separator (402) includes a first oxygen separator unit (404) and a second oxygen separator unit (406). The first oxygen separator unit is used to separate the aqueous electrolyte (E) introduced into the first oxygen separator unit (404) from the gaseous oxygen (O2), and the second oxygen separator unit is used to separate the aqueous electrolyte (E) introduced into the second oxygen separator unit (406) from the gaseous oxygen (O2).

12. The alkaline electrolysis apparatus (400) according to claim 11, characterized in that, The first oxygen separator unit (404) is configured to separate the aqueous electrolyte (E) from gaseous oxygen (O2), such that the aqueous electrolyte (E) has the first oxygen concentration due to the separation, and The second oxygen separator unit (406) is configured to separate the aqueous electrolyte (E) from gaseous oxygen (O2) such that the aqueous electrolyte (E) has the second oxygen concentration due to the separation.

13. The alkaline electrolysis apparatus (400) according to claim 11 or 12, characterized in that, The first oxygen separator unit (404) has a first oxygen separator outlet (122), and the second oxygen separator unit (406) has a second oxygen separator outlet (130).

14. The alkaline electrolysis apparatus (400) according to any one of claims 11 to 13, characterized in that, The oxygen-side branch line (408) branches off from the first oxygen-side electrolyte return guide line (124) and connects to the second oxygen separator unit (406) for supplying the aqueous electrolyte (E) having the first oxygen concentration to the second oxygen separator unit (406).

15. The alkaline electrolysis apparatus (200; 300; 500) according to any one of claims 1 to 10, characterized in that, The hydrogen separator (210) includes only the first hydrogen separator unit (214) and the second hydrogen separator unit (216) for two-stage separation of the aqueous electrolyte (E) and the gaseous hydrogen (H2), such that the oxygen separator (212) is configured for single-stage separation of the aqueous electrolyte (E) and the gaseous oxygen (O2).

Images