Electrolysis system having an ion exchanger

Abstract

The invention relates to an electrolysis system (21) comprising: at least one electrolysis cell (01); and a cathode-side water circuit (07) having a hydrogen separator (05); and an anode-side water circuit (06) having an oxygen separator (04); and an equalisation connection (22) which leads, coming from a cathode-side water connection (15), to the anode-side water circuit (06) via a pump (13) and an ion exchanger (12) via a node point (23) and an operating line (24); and an idle line (25) which (25) branches off upstream of the control line (24) and leads to the cathode-side gas connection (17).

Description

[0001] Description

[0002] Electrolysis system with an ion exchanger

[0003] The invention relates to an electrolysis system for the electrochemical decomposition of water to produce hydrogen and oxygen using electrolysis cells, with an anode-side water circuit and a cathode-side water circuit for gas separation. The purity of the water must be ensured by means of ion exchangers.

[0004] Electrolysis systems are known in various designs from the state of the art. Each system includes an electrolyzer. Various designs are used for this, with a so-called PEM electrolyzer being frequently employed. This system comprises a plurality of electrolysis cells, which are divided into an anode chamber and a cathode chamber by a polymer electrolyte membrane. Water electrolysis takes place in the electrolysis cells, for which an inlet is provided at least in the anode chamber. An outlet is located at the top of the anode chamber and at the top of the cathode chamber, through which the resulting gas, containing a proportion of water, is discharged.

[0005] On one anode side, there is usually a water circuit from the anode chamber outlet with an oxygen separator back to the anode chamber inlet. A circulation pump, a cooling device, and a filter assembly may also be present in the water circuit. To ensure sufficient water purity, some designs incorporate an ion exchanger in the anode-side water circuit.

[0006] The cathode side is usually constructed analogously to the anode side and thus also has a water circuit from the outlet of the cathode chamber via a hydrogen separator back to the inlet of the cathode chamber.

[0007] In systems where an ion exchanger is located directly in the respective water circuit, this makes it necessary to design it for the full flow through the water circuit and is therefore usually larger than is necessary to purify the water.

[0008] Alternatively, designs are known that include a cleaning circuit from the respective separator and back into the separator, with a pump and an ion exchanger present in the cleaning circuit. This allows for advantageous dimensioning.

[0009] However, it has also been shown to be disadvantageous that the water quality in the electrolyzer decreases during longer downtimes and that when it is restarted, the efficiency is reduced and the service life is impaired.

[0010] Another consideration is the water transfer from the anode side to the cathode side through the PEM membrane during electrolyzer operation. The transferred water must therefore be recirculated. In conventional systems, connections from the cathode-side water circuit to the anode-side water circuit are provided, with the connection typically including a pump and an ion exchanger.

[0011] The object of the present invention is to provide a way of ensuring the purity of the water even when the electrolyzer is not in operation and to keep the effort required for cleaning to a minimum.

[0012] The stated object is achieved by an electrolysis system according to the teaching of claim 1. Advantageous embodiments are the subject of the dependent claims. The generic electrolysis system serves for the electrochemical decomposition of water and thus for the production of hydrogen and oxygen. The electrolysis system has at least one electrolysis cell. As a rule, an electrolysis unit is used, which in turn has several electrolysis cells. The one or each individual electrolysis cell has an anode chamber and, on an opposite side separated by a membrane, a cathode chamber. The type of membrane used is initially irrelevant, although a polymer electrolyte membrane is preferably used. An anode is located in the anode chamber and a cathode is located opposite in the cathode chamber.

[0013] According to the intended purpose, during operation of the electrolysis system, a voltage is applied between the anode and the cathode of one or the respective electrolysis cell so that the electrolysis process can take place and hydrogen and oxygen are formed.

[0014] In contrast, it is intended that when the electrolysis system is at rest, there is no voltage between the anode and the cathode and consequently no gas formation occurs.

[0015] During electrolysis, gases are generated in the chambers, resulting in a flow from bottom to top. Separate removal of the resulting gases must be ensured. Accordingly, the cathode and anode chambers are usually flowed from bottom to top during operation of the electrolysis system.

[0016] To carry out the process, a water supply to the electrolysis cell is required. For this purpose, the electrolysis system has an anode-side water circuit. This can be divided into an anode-side water connection and an anode-side gas connection. The anode-side gas connection leads from an outlet of the anode chamber to an oxygen separator. During operation of the electrolysis cell, the gas connection carries a mixture of gas and water from the anode chamber to the oxygen separator. From there, a water connection leads back to an anode-side inlet on the anode chamber. Accordingly, during operation, water flows through the anode-side water connection from the oxygen separator to the anode chamber.

[0017] Similarly, the electrolysis system features a cathode-side water circuit. This circuit begins at a cathode-side outlet of the cathode chamber and leads to a hydrogen separator via a gas connection. During operation of the electrolysis cell, this gas connection also carries a mixture of gas and water from the cathode chamber to the hydrogen separator. From there, a water connection also leads back to a cathode-side inlet of the cathode chamber. Accordingly, during operation, water flows through the cathode-side water connection from the hydrogen separator to the cathode chamber.

[0018] A main pump and / or a cooling device and / or a filter can also be provided in both the anode-side and cathode-side water circuits. The order of the elements is also initially irrelevant, as is whether other devices are present in the water circuit.

[0019] To enable the return of the water that has transferred from the anode chamber to the cathode chamber during operation, a compensation connection is provided, which leads from the cathode-side water connection to the anode-side water circuit. To ensure the purity of the returned water, a pump and an ion exchanger are provided in the compensation connection. A cooling device and / or a filter can advantageously be provided in the compensation connection. The order of the elements is also initially irrelevant, as is whether additional devices are present in the compensation connection.

[0020] According to the invention, however, the equalizing connection is not routed directly to the anode-side water circuit, but first to a junction point. From there, an operating line leads to the anode-side water circuit and, as a branch, an additional idle line to the cathode-side gas connection.

[0021] This embodiment makes it possible, on the one hand, to deionize the transfer water returning from the cathode side to the anode side in a known manner during the return process. However, the special embodiment provides the possibility of continuing to operate a purification circuit when the electrolysis process is shut down.

[0022] The equalizing connection is designed to allow the return of water that has overflowed from the electrolysis cell via the operating line. This requires cleaning with an ion exchanger to prevent adverse ionic contamination on the anode side.

[0023] During operation of the electrolysis system, the equalization connection and subsequently the operating line are preferably flowed through, so that a flow from the cathode-side water connection to the anode-side water circuit occurs at least to compensate for the water that has overflowed in the electrolysis cell.

[0024] The equalizing connection can be connected at various points in the cathode-side water connection. Likewise, the operating line can be connected at various points in the anode-side water circuit.

[0025] If several electrolysis cells are present, it can advantageously be provided that on the underside of the cathode chambers and / or on the underside of the anode chamber, a water channel is arranged connecting the individual cathode chambers or the individual anode chambers, from which an inflow into the cathode chambers or the anode chamber is possible.

[0026] If a water channel is present on the underside of the cathode chamber and / or the anode chamber, the piping coming from the hydrogen separator or the oxygen separator of the associated cathode-side water connection or anode-side water connection is preferably connected to the cathode-side water channel or anode-side water channel, ie the water channel forms part of the water connection.

[0027] If several electrolysis cells are present, it can also be advantageously provided that a gas channel is arranged on the top side of the cathode chambers and / or on the top side of the anode chamber, connecting the individual cathode chambers or individual anode chambers, from which gas-water mixture formed during operation can be discharged from the cathode chambers or anode chambers.

[0028] If a gas channel is present, the piping of the associated gas connection to the hydrogen separator or the oxygen separator is connected to the associated gas channel, ie the gas channel is part of the gas connection.

[0029] The flexibility of process control, both during operation (i.e., when a voltage is applied between the anode and cathode and electrolysis is taking place), and in the idle state (when no voltage is applied to the electrolysis cell), is improved by a cross-current connection from the cathode chamber to the anode chamber. Depending on the operating state, the cross-current connection allows flow from the cathode chamber to the anode chamber or from the anode chamber to the cathode chamber.

[0030] Advantageously, there is a free passage from the underside of the anode chamber, ie in the area of ​​the inlet into the anode chamber, to the underside of the cathode chamber, ie also in the area of ​​the inlet into the cathode chamber.

[0031] If an anode-side water channel and / or cathode-side water channel is present, the water channels on the anode side and cathode side are advantageously connected to each other using the cross current connection.

[0032] Although the water overflowing during the process is intended to be returned via the equalizing connection and subsequently the operating line, it can also be provided that a portion of the water is also returned via the crossflow connection. Alternatively, it can also be provided that more water is returned via the equalizing connection than overflows from the chambers during the process. In this case, crossflow from the anode side through the crossflow connection to the cathode side is possible.

[0033] Furthermore, it can be provided that an adjustable valve or a check valve is arranged in the cross-current connection.

[0034] The connection of the equalizing connection to the cathode-side water connection can be made at various locations. The obvious solution is to connect it as a branch to a piping system connecting the hydrogen separator to the cathode chamber.

[0035] Alternatively, a connection to the hydrogen separator is also included, ensuring that only water and no gas is discharged via the equalization connection. For example, the hydrogen separator could have two adjacent water connections, one of which connects to the line to the cathode chamber and the other to the equalization connection.

[0036] Alternatively, a connection to the underside of the cathode chamber is also possible, for example, adjacent to the connection for the piping from the hydrogen separator. This allows the transfer water to be drained immediately before it enters the cathode chamber. The same applies here as before: when water is drained at the cathode chamber, essentially only water and no gas is drained. To achieve this, it must be ensured that the flow from the piping coming from the hydrogen separator is diverted proportionally directly into the equalization line without flowing through the cathode chamber.

[0037] If a cathode-side water channel is present and it is intended that the compensation connection is to be connected to the underside of the cathode chamber, the compensation connection is advantageously connected to the cathode-side water channel below the cathode chamber.

[0038] If a cross connection is present, the compensating connection can be connected to the cross connection in a particularly advantageous manner. Thus, part of the cross-flow connection, from the connection of the compensating connection to the cathode chamber, also forms the compensating connection. This enables particularly simple and yet suitable piping.

[0039] In all variants of the transfer water drainage from the bottom of the cathode chamber, it must be ensured that the transfer water is drained immediately before it enters the cathode chamber, so that the discharge of gas formed can be essentially excluded.

[0040] The connection of the operating line to the anode-side water circuit can also initially be made at any location.

[0041] In a preferred embodiment, the operating line is connected to the anode-side water connection. This minimizes the impact of the transfer water recirculation on the anode-side water circuit during operation of the electrolysis system, making it easy to implement.

[0042] The same applies to the connection of the operating line to the anode-side water connection as to the connection of the compensation connection to the cathode-side water connection.

[0043] Accordingly, it is possible to connect the operating line at the anode-side water connection to a piping leading from the oxygen separator to the anode chamber.

[0044] In a particularly advantageous embodiment, the operating line is connected to the underside of the anode chamber. This allows the recirculated transfer water to be fed to the anode chamber via a short route.

[0045] The connection of the operating line to the anode chamber can be established by connecting it to the underside of the anode chamber, parallel to a piping system coming from the oxygen separator. If an anode-side water channel is present on the underside of the anode chamber, the operating line can also advantageously be connected to the anode-side water channel.

[0046] If a cross connection is available, the service line can advantageously be connected to it. A portion of the cross connection, from the service line connection to the anode chamber, also forms a section of the service line. This enables particularly simple yet efficient piping.

[0047] A particular advantage of all variants with the connection of the operating line to the underside of the anode chamber is the return of the transfer water directly to the inlet in the anode chamber.

[0048] In an alternative design, the operating line is connected to the anode-side gas connection. While this requires more effort to account for the transfer water introduced into the anode-side gas connection, this variant allows for additional options, particularly with regard to operation in standby mode.

[0049] When connecting the operating line to the anode-side gas connection, it must be ensured that during operation of the electrolysis system the water supplied from the operating line is led to the oxygen separator together with the gas-water mixture from the anode-side gas connection.

[0050] It can also be provided that the operating line is connected to the top of the oxygen separator. If the idle line is to be connected to the cathode-side gas connection at the top of the cathode chamber—for example, for reasons of simpler piping—a connection to the cathode-side gas channel, if available, is preferred.

[0051] To enable different flow conditions during operation of the electrolysis system and in idle mode, it is both advantageous and obvious to install valves in the lines, connections, or branches. This can include a valve in the equalization line and / or a valve in the operating line and / or the idle line. It would also be possible to install a multi-port valve at the junction point.

[0052] In addition, it is also possible to provide one or more valves in the anode-side water connection and / or the cathode-side water connection and / or in the anode-side gas connection and / or in the cathode-side gas connection in order to be able to influence the flow both during operation and in the idle state.

[0053] Advantageously, during operation the idle line is shut off, for example by means of a valve, so that there is no flow there.

[0054] However, it is also possible that, as intended, a proportional flow through the idle line is present during operation of the electrolysis system and, in this respect, a cleaning circuit from the hydrogen separator and back to the hydrogen separator is present.

[0055] In the rest state, however, when no voltage is applied to the electrolysis cell, the rest line is preferably flowed through, wherein it is preferably provided that a flow is present from the rest line to the cathode chamber and from there via the cathode-side water connection to the compensation connection.

[0056] Depending on whether only the water in the cathode chamber or also the water in the anode chamber is to be cleaned via the ion exchanger in the equalizing connection in the idle state, the operating line is interrupted or also flows through, depending on the type of piping.

[0057] The pump installed in the equalization connection can create a flow from the cathode-side water connection through the equalization connection and then the idle line to the cathode-side gas connection. This means that the flow direction in the equalization connection from the cathode-side water connection to the junction point is the same both during operation and in the idle state of the electrolysis system.

[0058] During operation of the electrolysis system, the flow in the chambers of the electrolysis cell necessarily flows from bottom to top due to gas formation. In contrast, no direction is predetermined for the electrolysis cell's idle state. Therefore, it would also be possible to flow through the chambers from bottom to top for cleaning. However, a top-to-bottom flow through the cathode chamber and / or the anode chamber is particularly preferred for the idle state, opposite to the flow direction during operation.

[0059] With the preferred opposite flow through the cathode chamber, when connecting the idle line to the cathode-side gas connection, care must be taken to ensure that flow from the idle line to the top of the cathode chamber is possible in the idle state. This is preferably done by connecting the gas connection to a piping connecting the cathode chamber to the hydrogen separator, or by connecting it to a cathode-side gas channel. With a top-to-bottom flow through the cathode chambers in the idle state, the water from the bottom of the cathode chambers must obviously be redirected to the equalizing connection.

[0060] Various variants are available for this. In a first version, backflow occurs at least partially via the cathode-side water connection.

[0061] It is preferably provided that the water flowing through the cathode chamber from top to bottom is guided back to the equalizing connection via the cathode-side water connection, also in the opposite direction to the flow direction during operation. If the equalizing connection is connected to the piping between the hydrogen separator and the cathode chamber, the water will naturally flow backward through the section from the cathode chamber to the equalizing connection in the idle state. If, however, the equalizing connection is connected to the hydrogen separator, the water will naturally flow back to the hydrogen separator and from there into the equalizing connection in the idle state.

[0062] If, however, the equalizing connection is connected directly to the underside of the cathode chamber, the piping of the cathode-side water connection, i.e., from the hydrogen separator to the underside of the cathode chamber, is not flowing during the idle state. As previously explained, the equalizing connection can be connected to a cathode-side water channel or to a cross connection.

[0063] Furthermore, it is advantageously possible to flow through both chambers via the equalizing connection in the idle state. This means that flow occurs from the equalizing connection via the junction point and the idle line to the cathode chamber, and then flow occurs via another line from the equalizing connection to the anode chamber.

[0064] Various options are available for this. In a first variant, the operating line is used to conduct a water flow to the anode chamber even in the idle state. This means that in the operating state, the water essentially flows only through the operating line, while in the idle state, the deionized water in the equalizing connection is divided between the operating line and the idle line.

[0065] It is particularly advantageous to connect the operating line to the anode-side gas connection.

[0066] In a second variant, a second idle line to the anode-side gas connection is used parallel to the idle line to the cathode-side gas connection. In this case, the operating line preferably runs to the anode-side water connection. The second idle line can branch off from the first idle line or be connected to the equalizing connection via another node. At least during operation of the electrolysis system, the flow occurs via the operating line primarily to the anode-side water connection, and during idle mode, via the idle line to the anode-side gas connection and via the second idle line to the cathode-side gas connection.

[0067] In the case of cleaning the water from the anode chamber via the equalizing connection, it is obviously necessary to return the water from the anode chamber to the cathode side.

[0068] For this purpose, if the cross-flow connection is present, the water can advantageously be pumped in the resting state via the

[0069] A cross-current connection can be used to conduct water from the anode chamber to the cathode chamber, or from an advantageously provided anode-side water channel via the cross-current connection to an advantageously provided cathode-side water channel. However, a second design is particularly advantageous, in which the equalizing connection is directly connected to the cross-current connection. Thus, in the idle state, water can flow from both the anode chamber and the cathode chamber to the equalizing connection via the cross-current connection from both sides.

[0070] If water purification on the anode side is also required during operation, a purification loop can be provided, leading from and back to the anode-side water circuit. This also requires a pump and an ion exchanger in the purification loop. A cooling device and a filter can also be provided.

[0071] It is particularly advantageous if the cleaning loop leads from the anode-side water connection, for example, from the oxygen separator, to the anode-side gas connection. This allows water to flow from the oxygen separator via the cleaning loop back to the oxygen separator, particularly during operation. During idle operation, water flows from the anode-side water connection, for example, from the oxygen separator, via the cleaning loop to the anode-side gas connection and through the anode chamber back to the anode-side water connection.

[0072] The electrolysis system according to the invention enables a novel method according to the invention for controlling such an electrolysis system. The essential and advantageous method steps are clearly evident from the previous description of the electrolysis system according to the invention and its advantageous design.

[0073] A fundamental distinction must be made between the operating state of the electrolysis system and its idle state. During operation, a voltage is applied between the anode and the cathode, causing electrolysis and thus the formation of hydrogen and oxygen. This creates a circular flow in the anode-side water circuit and a circular flow in the cathode-side water circuit. A gas-water mixture flows from each chamber through the corresponding gas connection to the corresponding separator. There, the respective gas is separated, and the water is returned to the corresponding chamber via the corresponding water connection.

[0074] At the same time, water flows from the anode chamber into the cathode chamber during operation. To compensate for this, water from the anode-side water connection is fed via the equalizing connection and then the operating line back to the anode-side water circuit. The flow is generated by the pump in the equalizing connection, and an ion exchanger is also present to purify the water.

[0075] In the idle state, however, the connection from the anode to the cathode is voltage-free, thus eliminating electrolysis and gas formation. In the equalizing connection, however, the pump continues to operate, but the water is directed through the idle line to the cathode chamber.

[0076] Particularly advantageously, in the idle state, the water from the cathode-side water connection is led via the equalizing connection on the one hand via the idle line to the cathode chamber and on the other hand via the operating line or a second idle line to the anode chamber.

[0077] The following figures outline exemplary designs for an electrolysis system. They show:

[0078] Fig. 1 shows a first embodiment of an electrolysis system with a compensation connection connected to the hydrogen separator and an operating line to the anode chamber; Fig. 2 shows a second embodiment of an electrolysis system, wherein, in addition to the embodiment of Fig. 1, a second idle line leads to the anode-side gas connection;

[0079] Fig. 3 shows a third embodiment of an electrolysis system with a compensating connection connected to a cross current connection;

[0080] Fig. 4 shows a fourth embodiment of an optional cleaning loop on the anode side.

[0081] Figure 1 outlines a first embodiment of an electrolysis system 21 according to the invention. This system 21 comprises the electrolysis cell 01 with the anode chamber 02 and cathode chamber 03 located therein. The two chambers 02, 03 are separated by a PEM membrane. A water channel is located on the underside of each chamber 02, 03 to ensure easy water supply to the respective chamber 02, 03. Furthermore, the electrolysis system 21 comprises an oxygen separator 04 and a hydrogen separator 05.

[0082] On the right side of Figure 1 is the cathode-side water circuit 07. This 07 comprises a cathode-side water connection 15 from the hydrogen separator 05 to the cathode chamber 03 as well as a cathode-side gas connection 17 from the cathode chamber 03 to the hydrogen separator 05. During operation of the electrolysis system 21, water flows from the hydrogen separator 05 through the cathode-side water connection 15 to the underside of the cathode chamber 03 and a gas-water mixture flows from the top of the cathode chamber 03 through the cathode-side gas connection 17 to the hydrogen separator 05. On the left side of Figure 1 is the anode-side water circuit 06. This 06 comprises an anode-side water connection 14 from the oxygen separator 04 to the anode chamber 02 as well as an anode-side gas connection 16 from the anode chamber 02 to the oxygen separator 04.During operation of the electrolysis system 21, water flows from the oxygen separator 04 to the underside of the anode chamber 02 and a gas-water mixture flows from the top of the anode chamber 02 through the anode-side gas connection 16 to the oxygen separator 04.

[0083] The flow direction during operation of the electrolysis system 21 is indicated by the long arrows 08.

[0084] A cooler 11 is provided in each of the water connections 14, 15.

[0085] Also shown in this embodiment is a cross current connection 18 which connects the underside of the anode chamber 02 with the underside of the cathode chamber 03, ie in this case connects the respective water channels of the two chambers 02, 03 with each other.

[0086] Also shown in this embodiment is a cleaning loop 26, which leads from the oxygen separator 04 to the anode-side gas connection 16. A pump 13, an ion exchanger 12, and a cooler 11 are arranged in the cleaning loop 26.

[0087] By means of the cleaning loop 26, a partial cleaning of the water circulating in the anode-side water circuit is possible during operation of the electrolysis system 21.

[0088] Alternatively, it would also be possible to return the cleaning loop 26 directly to the oxygen separator 04 - see alternative line 27. The cleaning loop 26 is particularly advantageous in the idle state of the electrolysis system 21, allowing continued cleaning of the water in the anode chamber 02. The water flows from the cleaning loop 26 in the opposite direction through the anode chamber 02 and through the anode-side water connection 14, also in the opposite direction, back to the oxygen separator 04.

[0089] On the cathode side, a compensating connection 22 is connected to the hydrogen separator 05, which leads via a junction 23 and a service line 24 to the underside of the anode chamber 02, i.e., to the anode-side water channel. A pump 13, an ion exchanger 12, and a cooler 11 are arranged in the compensating connection 22. Thus, during operation of the electrolysis system 21, the water that has overflowed in the electrolysis cell 01 can be purified and returned to the anode side via the compensating connection 22.

[0090] Furthermore, there is a rest line 25, which leads from the node 23 to the cathode-side gas connection 17. It is intended that during operation of the electrolysis system

[0091] 21 the idle line 25 is interrupted. In the idle state of the electrolysis system 21, however, the operating line 24 is shut off and the flow from the equalizing connection

[0092] 22 leads via the rest line 25 to the cathode chamber 03. This 03 is flowed through backwards, whereby the water is then led backwards through the cathode-side water connection 15 back to the oxygen separator 05.

[0093] The intended flow direction for the rest state is outlined by the short arrows 09.

[0094] The following Figure 2 outlines another exemplary embodiment of an electrolysis system 31 according to the invention. Again, the electrolysis cell 01 with the anode chamber 02 and the cathode chamber 03 is present, as well as the oxygen separator 04 and the hydrogen separator 05.

[0095] Likewise, there is an anode-side water circuit 06 with the anode-side water connection 14 and the anode-side gas connection 16. Also consistent with the previous example, the cathode-side water circuit 07 with the cathode-side water connection 15 and the cathode-side gas connection 17 is present.

[0096] Likewise, consistent with the previous example, the compensating connection 32 with the adjoining operating line 34 is present.

[0097] In contrast to the previous example, however, it is now provided that, in addition to the pipe 35a from the node 33a to the cathode-side gas connection 17, there is also a second idle line 35b from a second node 33b to the anode-side gas connection 16.

[0098] First, in accordance with the previous example, it is provided that during operation of the electrolysis system 31 the operating line 34 is disconnected and the idle lines 35a, 35b are blocked.

[0099] In contrast, in the rest state of the electrolysis system 31 with the operating line 34 blocked, a flow through both rest lines 35a and 35b is provided parallel to the anode chamber 02 on the one hand and to the cathode chamber 03 on the other hand.

[0100] The water flowing backward in the cathode chamber 03 is returned to the hydrogen separator 05 via the cathode-side water line 15 as before.

[0101] In contrast, the water flowing backwards in the anode chamber 02 is first guided via the cross-flow connection 18 to the underside of the cathode chamber 03, so that the water can be returned from there via the cathode-side water connection 15.

[0102] Figure 3 outlines another preferred embodiment of an electrolysis system 41 according to the invention. Consistent with previous examples, this again comprises the electrolysis cell 01 with the anode chamber 02 and the cathode chamber 03. Likewise, the oxygen separator 04 and the hydrogen separator 05 are present, which 04, 05 are each integrated into the corresponding anode-side water circuit 06 and cathode-side water circuit 07, respectively.

[0103] In contrast to the previous embodiments, however, it is provided here that the compensating connection 42 is connected to the cross-current connection 18. The compensating connection 42 also has a pump 13, the ion exchanger 12, and a cooler 11.

[0104] The operating line 44 leads from the node 43 following the equalization connection 42 to the anode-side gas connection 16. The rest connection 45 connects the node 43 with the cathode-side gas connection 17, analogous to the previous examples.

[0105] In the operating state of the electrolysis system 41, the water to be returned from the cathode side flows from the underside of the cathode chamber 03 through a section of the cross current connection 18 via the compensation connection 42 and the operating line 44 to the anode-side gas connection 16.

[0106] In contrast, in the idle state of the electrolysis system 41, a flow is enabled from the equalization connection 42, on the one hand, through the operating line 44 and, on the other hand, through the idle connection 45, once to the anode-side gas connection 16 and, on the other hand, to the cathode-side gas connection 17. This leads to a backward flow through the anode chamber 02 and through the cathode chamber 03. At the bottom of the chambers 02, 03, the water coming from both sides is guided back to the equalization connection 42 through the cross-flow connection 18.

[0107] It can also be provided that, depending on the load, a portion of the purified water coming from the equalization connection 42 is also supplied proportionally via the rest line to the cathode-side gas connection 17 during operation of the electrolysis system 41.

[0108] Figure 4 outlines another example of an electrolysis system 51. This system particularly illustrates an alternative piping arrangement for cleaning on the anode side. The connection of a rest line from the equalizing connection 52 to the cathode-side gas connection 17, according to the invention, has been omitted.

[0109] In this exemplary embodiment, a cleaning loop is first sketched that corresponds to the first exemplary embodiment in Figure 1. In this respect, the same procedure as in the first example is possible.

[0110] However, during operation of the electrolysis system 51, the flow is directed from a cleaning connection 56 connected to the oxygen separator 04 via a junction 57 and a cleaning line 58 to the anode-side water connection 14 near the inlet to the anode chamber 02. This prevents any impairment of the flow of the gas-water mixture present in the gas connection 16.

[0111] In the idle state, however, the cleaning operating line 58 is shut off and the flow occurs, as in the first embodiment, from the cleaning connection 56 via a cleaning rest line 59 to the anode-side gas connection 16.

Claims

Patent claims 1. Electrolysis system (21,31,41) for the electrochemical production of hydrogen and oxygen comprising - a hydrogen separator (05) and an oxygen separator (04); and - at least one electrolysis cell (01) with an anode chamber (02) containing an anode and a cathode chamber (03) containing a cathode; and - a cathode-side water circuit (07) with a water connection (15) leading from the hydrogen separator (05) to the cathode chamber (03) and a gas connection (17) leading from the cathode chamber (03) to the hydrogen separator (05); and - an anode-side water circuit (06) with a water connection (14) leading from the oxygen separator (04) to the anode chamber (02) and a gas connection leading from the anode chamber (02) to the oxygen separator (04). (16) ; and - a compensating connection (22, 32, 42) which leads (22, 32, 42) from the cathode-side water connection (15) via a pump (13) and an ion exchanger (12) to a junction (23, 33, 43); and - an operating line (24, 34, 44) which leads (24, 34, 44) from the junction (23, 33, 43) to the anode-side water circuit (06); and - a quiescent line (25, 35, 45) which (25, 35, 45) from the node (23, 33, 43) to the cathode-side gas connection (17) leads. Electrolysis system (21, 31, 41) according to claim 1, wherein a cooler (11) and / or a filter and / or a pump is arranged in one or both water connections (14, 15); and / or wherein a cooler (11) and / or a filter is arranged in the compensating connection (22, 32, 42) and / or the operating line (24, 34, 44); and / or wherein a valve is arranged in the operating line (24, 34, 44) and / or the quiescent line (25, 35, 45) and / or at the junction (23, 33, 43). Electrolysis system (21, 31, 41) according to claim 1 or 2, comprising a transverse current connection (18) connecting the underside of the chambers (02, 03). Electrolysis system (41) according to claim 1 or 2, wherein the compensating connection (42) is sectionally connected to the cathode-side water connection (15) via a cross-flow connection (18) connecting the underside of the chambers (02,03) or is connected to the underside of the cathode chamber (03).Electrolysis system (41) according to any one of claims 1 to 4, wherein the operating line (24, 34) leads to the anode-side water connection (14); or wherein the operating line (44) leads to the anode-side gas connection (16). Electrolysis system (21, 31) according to claim 1 or 2, wherein the operating line (24, 34) leads section by section via a cross-flow connection (18) connecting the underside of the chambers (02, 03) to the anode-side water connection (14) or is connected to the underside of the anode chamber (02). Electrolysis system (21, 31, 41) according to any one of claims 1 to 6, wherein the quiescent line (25, 35, 45) is interrupted during operation and is flowed through when at rest; and wherein, in particular, the operating line (24, 34, 44) is flowed through during operation and is interrupted when at rest. Electrolysis system (21) according to any one of claims 1 to 7, wherein, according to the design, the cathode chamber (03) is flowed through from top to bottom via the quiescent line (25) from the compensating connection (22) when at rest. Electrolysis system (31, 41) according to one of claims 1 to 7, wherein the operating line (44) or a second quiescent line (35b) leads to the anode-side gas connection (16), wherein, as intended, in the quiescent state, the cathode chamber (03) is supplied from top to bottom via the quiescent line (35a, 45) and the anode chamber (02) via the operating line (44) or second quiescent line (35b), respectively, coming from the compensating connection (32, 42).Electrolysis system (21, 31) according to one of claims 7 to 9, wherein, according to its intended use, in the resting state, at least sectionally a flow from the cathode chamber (03) towards the hydrogen separator (05) is present in the cathode-side water connection (15). Electrolysis system (21) according to one of claims 1 to 10, comprising a cleaning loop (26) which leads from the anode-side water connection (14) to the anode-side gas connection (16) and includes a pump (13) and an ion exchanger (12). Electrolysis system (21) according to claim 11, wherein, according to its intended operation, a flow is provided from the cleaning loop (26) to the oxygen separator (04) and, in the standby state, a flow is provided to the anode chamber (02); and / or wherein, according to its intended operation, in the standby state, a flow is provided in the anode-side water connection (14) from the anode chamber (02) towards the oxygen separator (04). Method for controlling an electrolysis system (21, 31, 41) according to one of the preceding claims, wherein in the operation of the electrolysis system (21, 31, 41) a voltage is applied between the anode and the cathode and a gas-water mixture flows through the respective gas connection (16, 17) from the associated chamber (02, 03) to the associated separator (04, 05) and water flows from the respective separator (04, 05) through the associated water connection (14, 15) to the associated chamber (02, 03), wherein a flow is diverted from the cathode-side water connection (15) by a pump and is caused by a compensating connection (22, 32, 42) through an ion exchanger (12) and through a service line (24, 34, 44) to the anode-side water circuit (06);and wherein in the rest state of the electrolysis system (21,31,41) there is no voltage between the anode and the cathode, wherein a pump (13) causes a flow from the cathode-side water connection (15) through a compensating connection (22,32,42) through an ion exchanger (12) and through a quiescent line (25,35,45) to the cathode-side gas connection (17) and further to the cathode chamber (03).

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