Electrolysis system with ion exchanger

Abstract

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

Description

Technical Field

[0001] The present invention relates to an electrolysis system for electrochemically decomposing water to produce hydrogen and oxygen using an electrolytic cell, wherein the electrolysis system has an anode-side water circulation loop and a cathode-side water circulation loop for separating gases, wherein the purity of the water is ensured by means of an ion exchanger. Background Art

[0002] Various designs of electrolysis systems are known from the prior art. In any case, such electrolysis systems include an electrolyzer. For this purpose, different designs are used, among which so-called PEM electrolyzers are usually used. The PEM electrolyzer has a plurality of electrolysis cells, which are divided into an anode chamber and a cathode chamber by a polymer electrolyte membrane. The electrolysis of water takes place in these electrolysis cells, for which at least an inlet is provided at the anode chamber. At the upper side of the anode chamber and at the upper side of the cathode chamber, there are outlets, through which the generated gas with some water is discharged.

[0003] On the anode side, there is usually a water circulation loop, which returns from the outlet of the anode chamber with the oxygen separator to the inlet at the anode chamber. If necessary, there are also circulation pumps, cooling devices and filtering components in the water circulation loop. In order to ensure that the water has sufficient purity, in some designs, an ion exchanger is used for the anode side water circulation loop.

[0004] The cathode side is generally constructed similarly to the anode side and therefore also has a water circulation loop from the outlet of the cathode chamber via a hydrogen separator back to the inlet of the cathode chamber.

[0005] For systems in which the ion exchanger is arranged directly in the respective water circuit, this results in the ion exchanger having to be dimensioned for the entire throughflow rate of the water circuit and therefore usually larger than is necessary for purifying the water.

[0006] Alternatively, embodiments are known in which there is a cleaning circuit coming from the respective separator and returning to the separator, wherein a pump and an ion exchanger are present in the cleaning circuit. The cleaning circuit can thus be advantageously dimensioned.

[0007] However, it has also proven to be disadvantageous in that in case of longer downtimes the water quality in the electrolyser can deteriorate and when restarted the efficiency is reduced and the service life is negatively affected.

[0008] Furthermore, it is necessary to consider that during operation of the electrolyzer, water can cross over from the anode side to the cathode side through the PEM membrane. Therefore, the water that crosses over must be returned. In this regard, in known systems, a connection is provided from the cathode side water circuit to the anode side water circuit, wherein a pump and an ion exchanger are usually provided in this connection. Summary of the invention

[0009] The object of the present invention is to provide a solution which ensures the purity of the water even when the electrolyser is not in operation and at the same time keeps the purification effort low.

[0010] The stated object is achieved by an electrolysis system according to the teaching of claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0011] This type of electrolysis system is used for the electrochemical decomposition of water and thus the production of hydrogen and oxygen. In this case, the electrolysis system has at least one electrolysis cell. Usually, an electrolysis unit is used, which in turn has a plurality of electrolysis cells. One, or more precisely each individual electrolysis cell, has an anode chamber and a cathode chamber on the opposite side separated by a membrane. Although polymer electrolyte membranes are preferably used, it is currently irrelevant which type of membrane is used here. In the anode chamber there is an anode and, oppositely, in the cathode chamber there is a cathode.

[0012] As provided, during operation of the electrolysis system, a voltage is applied between the anode and the cathode of one, or more precisely of each electrolysis cell, so that an electrolysis process can take place and hydrogen and oxygen can be formed in the process.

[0013] In contrast, according to regulations, in the idle state of the electrolysis system, no voltage is present between the anode and the cathode and therefore no gas is formed.

[0014] During the electrolysis process, gases are produced in the chamber, so that a flow from bottom to top is formed. In this case, it is necessary to ensure that the gases produced are discharged separately. Accordingly, during the operation of the electrolysis system, it is obvious that the flow through the cathode chamber and the anode chamber is usually from bottom to top.

[0015] In order to carry out the method, it is necessary to supply water to the electrolytic cell. For this purpose, the electrolysis system has an anode-side water circulation loop. The anode-side water circulation loop can be divided into an anode-side water connection and an anode-side gas connection. Here, the anode-side gas connection leads from the outlet of the anode chamber to the oxygen separator. During the operation of the electrolytic cell, the gas connection guides the mixture of gas and water from the anode chamber to the oxygen separator as required. From there, the water connection leads back to the anode-side inlet at the anode chamber. Accordingly, during operation, the anode-side water connection from the oxygen separator to the anode chamber is flowed through by water as required.

[0016] Similarly, the electrolysis system has a cathode-side water circulation loop. This cathode-side water circulation loop starts at the cathode-side outlet of the cathode chamber and is led to the hydrogen separator by means of a gas connection. During operation of the electrolyzer, the gas connection also leads the mixture of gas and water from the cathode chamber to the hydrogen separator. Likewise, the water connection leads from there back to the cathode-side inlet at the cathode chamber. Accordingly, during operation, the cathode-side water connection from the hydrogen separator to the cathode chamber is flowed through by water.

[0017] A main pump and / or a cooling device and / or a filter may also be provided in the anode-side water circulation loop and the cathode-side water circulation loop. The order of the elements is also currently irrelevant here, as is the case with the presence of other devices in the water circulation loop.

[0018] In order to be able to return the water that crosses over from the anode chamber to the cathode chamber during operation, a compensating connection is provided, which leads from the cathode-side water connection to the anode-side water circuit. In order to ensure the purity of the returned water, a pump and an ion exchanger are provided in the compensating connection.

[0019] In this case, a cooling device and / or a filter can advantageously be arranged in the compensating connection. The order of the elements is also currently irrelevant here, as is the case with the presence or absence of further devices in the compensating connection.

[0020] According to the invention, however, the compensating connection does not lead directly to the anode-side water circuit, but first to a node, from which an operating line leads to the anode-side water circuit and, as a branch, an off-line line also leads to the cathode-side gas connection.

[0021] With this embodiment, on the one hand, the transfer water returned from the cathode side to the anode side can be deionized in a known manner during the return. However, it is particularly advantageous to continue to operate the purification circuit when the electrolysis is stopped, which is achieved by a special embodiment.

[0022] The purpose of providing the compensating connection is basically to enable the water that has been overtaken in the electrolytic cell to be returned via the service line. Here, it is necessary to purify it with the aid of an ion exchanger in order to avoid an unfavorable ion load on the anode side.

[0023] During operation of the electrolysis system, a flow preferably occurs through the compensating connection and thus through the operating line, so that a flow occurs from the cathode-side water connection to the anode-side water circuit, which serves at least to compensate for the water overrun in the electrolysis cells.

[0024] Here, the compensating connection can be connected at different locations of the cathode-side water connection. Likewise, the service line can be connected at different locations of the anode-side water circuit.

[0025] If a plurality of electrolytic cells are present, it can advantageously be provided that a water channel is arranged on the underside of the cathode space and / or on the underside of the anode space, respectively, which connects the individual cathode spaces or the individual anode spaces and from which water can flow into the cathode space or the anode space.

[0026] If there is a water channel on the lower side of the cathode chamber and / or anode chamber, the pipeline from the hydrogen separator or 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, that is, the water channel forms part of the water connection.

[0027] If a plurality of electrolysis cells are present, provision can likewise advantageously be made for gas channels connecting the individual cathode chambers or the individual anode chambers to be arranged on the upper side of the cathode chamber and / or on the upper side of the anode chamber, respectively, through which gas channels a gas-water mixture formed during operation can be discharged from the cathode chamber or anode chamber.

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

[0029] If a cross-flow connection is provided from the cathode chamber to the anode chamber, the flexibility for process management is improved both during operation (i.e., voltage is applied between anode and cathode and electrolysis is taking place) and in the shutdown state (no voltage is applied to the electrolysis cell). In this case, it is provided that, depending on the operating state, flow can flow from the cathode chamber to the anode chamber or from the anode chamber to the cathode chamber via the cross-flow connection.

[0030] Advantageously, the cross-flow connection is a free passage from the underside of the anode chamber, ie in the region of the inlet into the anode chamber, to the underside of the cathode chamber, ie likewise in the region of the inlet into the cathode chamber.

[0031] If anode-side water channels and / or cathode-side water channels are present, the water channels on the anode side and cathode side are advantageously connected to one another by means of cross-flow connections.

[0032] Although during operation it is provided that the water which is crossed over by the process is returned via the compensating connection and subsequently via the operating line, it can be provided on the one hand that a portion of the water is additionally returned via the cross-flow connection. On the other hand it can also be provided that more water is returned via the compensating connection than the water which crosses over the chamber during the process. In this case, there can be a cross-flow from the anode side through the cross-flow connection to the cathode side.

[0033] Furthermore, it can be provided that an adjustable valve or non-return valve is arranged in the cross-flow connection.

[0034] The connection of the compensating connection at the cathode-side water connection can be made at different locations. Obviously, the connection at the pipeline connecting the hydrogen separator to the cathode chamber can be made as a branch.

[0035] Also as an alternative, the electrolysis system comprises a connection at the hydrogen separator, wherein it is ensured that only water and no gas is discharged via the compensating connection. Obviously, at the hydrogen separator, for example, two adjacent water connections can be provided, wherein one is connected to the line of the cathode chamber and the other is connected to the compensating connection.

[0036] Alternatively, the connection can be made at the bottom of the cathode chamber, for example at the connection of the pipeline adjacent to the hydrogen separator. This allows the transfer water to be discharged immediately before it enters the cathode chamber. In this case, as before, it is also applicable that when the water is discharged at the cathode chamber, essentially only water and no gas is discharged. To this end, it is ensured that the flow out of the pipeline from the hydrogen separator is partially branched directly into the compensation line without flowing through the cathode chamber.

[0037] If a cathode-side water channel is present and provision is made for the compensating connection to be connected at the bottom side of the cathode space, the compensating connection is advantageously connected at the cathode-side water channel below the cathode space.

[0038] If a transverse connection is present, the compensating connection can be connected to the transverse connection in a particularly advantageous manner. Thus, a portion of the transverse flow connection from the connection of the compensating connection to the cathode chamber also forms the compensating connection. This allows a particularly simple and at the same time suitable pipeline to be realized.

[0039] In all variants of discharge of the transfer water from the underside of the cathode space, it is ensured that the transfer water is discharged immediately before it flows into the cathode space, so that discharge of the gases formed is essentially impossible.

[0040] The connection of the operating line to the anode-side water circulation loop can also now be carried out at any location.

[0041] In a preferred embodiment, the operation pipeline is connected to the anode side water connection portion. Thus, during the operation of the electrolysis system, the return of the transferred water has minimal impact on the anode side water circulation loop, and thus the anode side water circulation loop is easy to implement.

[0042] This applies analogously to the connection of the service line to the anode-side water connection, as well as to the connection of the compensating connection to the cathode-side water connection.

[0043] Correspondingly, for the anode-side water connection, a service line can be connected to the line leading from the oxygen separator to the anode chamber.

[0044] In a particularly advantageous embodiment, the service line is connected to the underside of the anode chamber. As a result, the returning transfer water is supplied to the anode chamber over a short path.

[0045] The connection of the service line to the anode space can be effected here via a connection at the underside of the anode space, parallel to the line coming from the oxygen separator.

[0046] If an anode-side water channel is present on the underside of the anode space, it is also possible to connect the service line to the anode-side water channel in an advantageous manner.

[0047] If a transverse connection is present, the service line can advantageously be connected to the transverse connection. In this case, a part of the transverse connection from the connection of the service line to the anode chamber simultaneously forms a part of the service line. This allows a particularly simple and at the same time suitable pipe laying.

[0048] For all variants in which the service line is connected to the underside of the anode space, it is particularly advantageous to return the transfer water directly into the anode space.

[0049] In an alternative embodiment, the operating line is connected to the anode-side gas connection. Although this requires more work to take into account the transfer water introduced into the anode-side gas connection, this variant provides additional options, especially in terms of operating management in shutdown conditions.

[0050] When connecting a service line to the anode-side gas connection, care must be taken that during operation of the electrolysis system, water supplied from the service line is conducted together with the gas-water mixture from the anode-side gas connection to the oxygen separator.

[0051] Here too, provision can be made for the service line to be connected to the upper side of the oxygen separator.

[0052] If, for example for reasons of simpler piping, the shutdown line is to be connected to the cathode-side gas connection at the cathode chamber top side, then a connection to the cathode-side gas channel, if any, is preferably provided for this purpose.

[0053] In order to achieve different flow conditions during operation and in the shutdown state of the electrolysis system, it is both advantageous and obvious to use valves in the lines or in the connections or in the branch flows. It can be provided that there are valves in the compensation line and / or valves in the operating line and / or in the shutdown line. Multiway valves can also be provided in the nodes.

[0054] Furthermore, one or more valves may be provided in each of the anode-side water connection and / or cathode-side water connection and / or anode-side gas connection and / or cathode-side gas connection in order to be able to influence the flow during operation and in standstill conditions.

[0055] Advantageously, the shutdown line is blocked during operation, for example by means of a valve, so that no flow occurs there.

[0056] However, even during operation of the electrolysis system, a partial flow through the shutdown line may be present as required, in the sense that a purge circuit is present which originates from the hydrogen separator and returns to the hydrogen separator.

[0057] In contrast, in the shutdown state, when no voltage is applied to the electrolytic cell, water preferably flows through the shutdown line, wherein preferably provision is made for a flow from the shutdown line to the cathode space and from there via the cathode-side water connection to the equalizing connection.

[0058] Depending on whether only the water in the cathode space or also the water in the anode space is to be purified via the ion exchanger in the equalizing connection in the idle state, the service line is interrupted or also flows through it, depending on the type of pipeline.

[0059] By means of the pump present in the compensating connection, a flow can be generated from the cathode-side water connection via the compensating connection and then via the shutdown line to the cathode-side gas connection. That is, the flow direction in the compensating connection from the cathode-side water connection to the node is the same during operation and in the stationary state of the electrolysis system.

[0060] During operation of the electrolysis system, the flow in the chambers of the electrolysis cell is necessarily from bottom to top due to the formation of gas. In contrast, for the shutdown state of the electrolysis cell, no direction is predetermined. In this regard, it is also possible to flow through the chambers from bottom to top for purification. However, for the shutdown state, it is particularly preferred to flow through the cathode chamber and / or the anode chamber from top to bottom, in contrast to the flow direction given during operation.

[0061] In the case of a flow through the cathode chamber preferably in the opposite direction, when connecting the shutdown line to the cathode-side gas connection, care should be taken to ensure that in the shutdown state a flow can flow from the shutdown line to the upper side of the cathode chamber. In this case, preferably a connection is provided in a line connected to the gas connection, which connects the cathode chamber to the hydrogen separator, or a connection is provided to the cathode-side gas channel.

[0062] If there is a flow from top to bottom through the cathode chamber in the idle state, the water obviously has to return from the underside of the cathode chamber to the compensating connection.

[0063] There are various variants available for this purpose. In a first embodiment, the return flow is at least partially via the cathode-side water connection.

[0064] In this case, it is preferably provided that the water flowing through the cathode chamber from top to bottom in the opposite direction is led back to the compensating connection via the cathode-side water connection, also in the opposite direction to the flow direction during operation. If the compensating connection is connected to the pipeline between the hydrogen separator and the cathode chamber, then in the idle state the section from the cathode chamber to the compensating connection is obviously flowed in the reverse direction. However, if, in contrast, the compensating connection is connected to the hydrogen separator, then in this embodiment, in the idle state the water obviously flows back to the hydrogen separator and from there into the compensating connection.

[0065] If, in contrast, the compensating connection is connected directly to the underside of the cathode chamber, then in the shutdown state, the line of the cathode-side water connection, i.e. from the hydrogen separator to the underside of the cathode chamber, is not flowed through. In this case, as described above, the compensating connection can be connected to the cathode-side water channel or to the transverse connection.

[0066] Furthermore, in the shutdown state, flow can advantageously flow through both chambers via the compensating connection. That is, there is a flow from the compensating connection via the node and the shutdown line to the cathode chamber, and there is also a flow from the compensating connection via another line to the anode chamber.

[0067] There are several possibilities for this. In a first variant, the operating line is used to conduct the water flow to the anode chamber even in the idle state. That is, in the operating state substantially only the flow flows through the operating line, and in the idle state the deionized water in the equalizing connection is distributed between the operating line and the idle line. It is particularly advantageous to connect the operating line to the anode-side gas connection for this purpose.

[0068] In a second variant, a second additional shutdown line to the anode-side gas connection is used together with the shutdown line to the cathode-side gas connection. In this case, the operating line meaningfully extends to the anode-side water connection. In this case, it can be provided that the second shutdown line branches off from the first shutdown line or is connected to the compensating connection via a further node. At least during operation of the electrolysis system, the flow essentially flows via the operating line to the anode-side water connection, and in the shutdown state flows via the shutdown line to the anode-side gas connection and via the second shutdown line to the cathode-side gas connection.

[0069] If the water from the anode compartment is purified via the compensating connection, it is obviously necessary to return the water from the anode compartment to the cathode side.

[0070] For this purpose, water can advantageously be conducted in the idle state via a cross-flow connection from the anode space to the cathode space, if present, or via a cross-flow connection to an advantageously present cathode-side water channel, if an anode-side water channel is advantageously present.

[0071] However, the second embodiment is particularly advantageous, in which the compensating connection is directly connected to the cross-flow connection. Thus, in the shutdown state, water can flow from both the anode chamber and the cathode chamber via the cross-flow connection to the compensating connection from both sides.

[0072] If the anode side water also needs to be purified during operation, a purification circuit can be set up to and from the anode side water circulation circuit. In this case, a pump and an ion exchanger are also required in the purification circuit. In addition, a cooling device and a filter can also be provided.

[0073] In this case, it is particularly advantageous if the purge circuit leads from the anode-side water connection, for example from the oxygen separator, to the anode-side gas connection. This makes it possible, in particular, during operation to lead water from the oxygen separator via the purge circuit back to the oxygen separator, and in the idle state to lead water from the anode-side water connection, for example from the oxygen separator via the purge circuit to the anode-side gas connection and back through the anode space into the anode-side water connection.

[0074] The electrolysis system according to the invention enables the novel method according to the invention for controlling such an electrolysis system. Important and advantageous method steps are apparent from the previous description of the electrolysis system according to the invention and its advantageous embodiments.

[0075] In principle, a distinction is 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, whereby electrolysis is achieved and hydrogen and oxygen are formed. In this case, a circulating flow is generated in the anode-side water circuit and a circulating flow is generated in the cathode-side water circuit. The gas-water mixture flows from the respective chamber via the associated gas connection to the associated separator. There, the respective gas is separated, while the water is led back to the associated chamber via the associated water connection.

[0076] At the same time, during operation, water crosses over from the anode chamber into the cathode chamber. To compensate for this, it is provided that the water from the anode-side water connection is led back to the anode-side water circuit via the compensating connection and then via the operating line. This flow is caused by a pump in the compensating connection, wherein an ion exchanger is also provided to purify the water.

[0077] In contrast, in the shutdown state, the connection from the anode to the cathode is voltage-free, so that there is obviously no electrolysis to form gas. In contrast, the pump in the equalizing connection continues to operate, but only water is conducted to the cathode chamber via the shutdown line.

[0078] It is particularly advantageous if, in the idle state, water is conducted via the compensating connection from the cathode-side water connection via the idle line to the cathode space on the one hand and via the operating line or the second idle line to the anode space on the other hand. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] The following figures depict exemplary embodiments of electrolysis systems.

[0080] Figure 1 A first embodiment of an electrolysis system is shown, the electrolysis system having a compensating connection connected to a hydrogen separator and a service line to an anode chamber;

[0081] Figure 2 A second embodiment of an electrolysis system is shown, wherein as a Figure 1 In addition to the embodiment of the present invention, there is also a second shutdown pipeline leading to the anode side gas connection part;

[0082] Figure 3 A third embodiment of an electrolysis system is shown having a compensating connection coupled at a cross-flow connection;

[0083] Figure 4 A fourth embodiment is shown for an optional purge circuit on the anode side. DETAILED DESCRIPTION

[0084] Figure 1 A first embodiment of an electrolysis system 21 according to the invention is depicted. The electrolysis system 21 first has an electrolysis cell 01 having an anode chamber 02 and a cathode chamber 03 located therein. The two chambers 02, 03 are separated by a PEM membrane. There is a water channel at the lower side of each chamber 02, 03, respectively, to ensure that water can be easily supplied to each chamber 02, 03. In addition, the electrolysis system 21 also includes an oxygen separator 04 and a hydrogen separator 05.

[0085] The cathode side water circulation loop 07 is located Figure 1 The cathode side water circulation loop 07 includes a cathode side water connection 15 from the hydrogen separator 05 to the cathode chamber 03 and a cathode side gas connection 17 from the cathode chamber 03 to the hydrogen separator 05. During the operation of the electrolysis system 21, water flows from the hydrogen separator 05 to the lower side of the cathode chamber 03 through the cathode side water connection 15, and the gas-water mixture flows from the upper side of the cathode chamber 03 to the hydrogen separator 05 through the cathode side gas connection 17.

[0086] Anode side water circulation loop 06 is located at Figure 1The anode side water circulation loop 06 includes an anode side water connection 14 from the oxygen separator 04 to the anode chamber 02 and 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 lower side of the anode chamber 02, and a gas-water mixture flows from the upper side of the anode chamber 02 to the oxygen separator 04 through the anode side gas connection 16.

[0087] The flow direction during operation of the electrolysis system 21 is depicted by long arrows 08 .

[0088] A cooler 11 is provided in each of the water connections 14 , 15 .

[0089] In this exemplary embodiment, a cross-flow connection 18 is also shown, which connects the underside of the anode chamber 02 to the underside of the cathode chamber 03 , that is to say in this case connects the corresponding water channels of the two chambers 02 , 03 to one another.

[0090] In this exemplary embodiment, a purge circuit 26 is also shown, which leads from the oxygen separator 04 to the anode-side gas connection 16. In this case, a pump 13, an ion exchanger 12 and a cooler 11 are arranged in the purge circuit 26.

[0091] The water circulating in the anode-side water circuit can be partially purified by means of the purification circuit 26 during operation of the electrolysis system 21 .

[0092] Alternatively, the purification circuit 26 can also be led back directly to the oxygen separator 04 , see alternative line 27 .

[0093] It is particularly advantageous that, when the electrolysis system 21 is in a shutdown state, the water in the anode chamber 02 can continue to be purified by means of the purification circuit 26. In this case, the water flows from the purification circuit 26 through the anode chamber 02 in the opposite direction and also flows through the anode-side water connection 14 back to the oxygen separator 04 in the opposite direction.

[0094] On the cathode side, a compensating connection 22 is connected at the hydrogen separator 05, which leads to the lower side of the anode chamber 02, that is, to the anode side water channel via a node 23 and an operating pipeline 24. A pump 13, an ion exchanger 12 and a cooler 11 are arranged in the compensating connection 22. Therefore, during the operation of the electrolysis system 21, the water that has crossed over to the electrolysis cell 01 can be purified via the compensating connection 22 and returned to the anode side again.

[0095] There is also a shutdown line 25 which leads from the node 23 to the cathode-side gas connection 17. Provision is made here for the shutdown line 25 to be interrupted during operation of the electrolysis system 21. In contrast, in the shutdown state of the electrolysis system 21, the operating line 24 is blocked and the flow from the compensation connection 22 is led via the shutdown line 25 to the cathode chamber 03. This cathode chamber 03 is flowed in reverse, wherein the water then flows back in reverse to the oxygen separator 05 via the cathode-side water connection 15.

[0096] The intended flow direction for the idle state is indicated here by a short arrow 09 .

[0097] In the subsequent Figure 2 A further embodiment of an electrolysis system 31 according to the invention is depicted in . This electrolysis system again has an electrolysis cell 01 with an anode chamber 02 and a cathode chamber 03 as well as an oxygen separator 04 and a hydrogen separator 05 .

[0098] There is also an anode-side water circuit 06 with an anode-side water connection 14 and an anode-side gas connection 16. There is also a cathode-side water circuit 07 with a cathode-side water connection 15 and a cathode-side gas connection 17, in accordance with the previous example.

[0099] Likewise in accordance with the previous examples, there is a compensating connection 32 and a service line 34 connected thereto.

[0100] However, in contrast to the previous example, provision is now made for a second shutdown line 35 b from the second node 33 b to the anode-side gas connection 16 in addition to the line 35 a from the node 33 a to the cathode-side gas connection 17 .

[0101] Firstly, in accordance with the previous example, provision is made for the operating line 34 to be opened and the shutdown lines 35 a , 35 b to be blocked during operation of the electrolysis system 31 .

[0102] In contrast, in the shutdown state of the electrolysis system 31 , with the operating line 34 blocked, there is a flow through both the shutdown lines 35 a and 35 b , which flows simultaneously to the anode space 02 on the one hand and to the cathode space 03 on the other hand.

[0103] The water flowing in the cathode chamber 03 in the reverse direction is guided back to the hydrogen separator 05 via the cathode-side water line 15 as before.

[0104] In contrast, the water flowing in the anode space 02 in the opposite direction is first conducted via the cross-flow connection 18 to the underside of the cathode space 03 , so that the water can be conducted back from there via the cathode-side water connection 15 .

[0105] Figure 3Another preferred embodiment of an electrolysis system 41 according to the invention is depicted. In line with the previous examples, this electrolysis system also has an electrolysis cell 01 with an anode chamber 02 and a cathode chamber 03. It also has an oxygen separator 04 and a hydrogen separator 05, which are respectively integrated into the corresponding anode-side water circulation loop 06 or cathode-side water circulation loop 07.

[0106] However, in contrast to the previous exemplary embodiments, provision is made here for a compensating connection 42 to be connected to the cross-flow connection 18 . Here, the compensating connection 42 also has a pump 13 , an ion exchanger 12 and a cooler 11 .

[0107] The operating line 44 now leads from the node 43 downstream of the compensation connection 42 to the anode-side gas connection 16. The shutdown connection 45 connects the node 43 to the cathode-side gas connection 17 similarly to the previous example.

[0108] In the operating state of the electrolysis system 41 , water returning from the cathode side flows from the bottom of the cathode chamber 03 through a part of the cross-flow connection 18 via the compensation connection 42 and the service line 44 to the anode-side gas connection 16 .

[0109] In contrast, in the shutdown state of the electrolysis system 41, a flow can be achieved from the compensating connection 42 via the operating line 44 to the anode-side gas connection 16 on the one hand and via the shutdown connection 45 to the cathode-side gas connection 17 on the other hand. This results in a countercurrent flow through the anode chamber 02 and through the cathode chamber 03. On the lower side of the chambers 02, 03, the water from both sides is led back to the compensating connection 42 via the cross-flow connection 18.

[0110] Provision can also be made here that, depending on the load, a portion of the purified water from the compensation connection 42 is also supplied simultaneously and partially via the shutdown line to the cathode-side gas connection 17 during operation of the electrolysis system 41 .

[0111] Figure 4 A further example of an electrolysis system 51 is depicted. In particular, an alternative piping arrangement for the anode-side cleaning is shown here. The connection according to the invention of the shutdown line from the compensation connection 52 to the cathode-side gas connection 17 is not shown here.

[0112] In this embodiment, firstly, Figure 1 The first embodiment corresponds to the purification circuit of . In this respect, the same process management as the first example is possible.

[0113] However, it is provided that during operation of the electrolysis system 51, the flowing stream is conducted from the purge connection 56 connected to the oxygen separator 04 via the node 57 and from the purge operation line 58 into the anode chamber 02, which is connected in the vicinity of the inlet to the anode-side water connection 14. Any negative influence on the flow of the gas-water mixture present in the gas connection 16 is thereby avoided.

[0114] In contrast, in the shutdown state, the purge operation line 58 is blocked, and gas flows from the purge connection 56 to the anode-side gas connection 16 via the purge shutdown line 59 as in the first embodiment.

Claims

1. An electrolysis system (21, 31, 41) for electrochemically producing hydrogen and oxygen, the electrolysis system comprising: - Hydrogen separator (05) and oxygen separator (04); as well as - at least one electrolytic cell (01) having an anode chamber (02) with an anode and a cathode chamber (03) with a cathode; and - a cathode-side water circulation loop (07), which has 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 circulation loop (06) having a water connection (14) leading from the oxygen separator (04) to the anode chamber (02) and a gas connection (16) leading from the anode chamber (02) to the oxygen separator (04); and a compensating connection (22, 32, 42) which leads from the cathode-side water connection (15) via a pump (13) and an ion exchanger (12) to a node (23, 33, 43); and - an operation pipeline (24, 34, 44), which leads from the node (23, 33, 43) to the anode side water circulation loop (06); and A shutdown line (25, 35, 45) leading from the node (23, 33, 43) to the cathode-side gas connection (17).

2. The electrolysis system (21, 31, 41) according to claim 1, in, A cooler (11) and / or a filter and / or a pump are arranged in one water connection (14, 15) or in 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 pipeline (24, 34, 44); and / or wherein: Valves are arranged in the operating line (24, 34, 44) and / or the shutdown line (25, 35, 45) and / or in the node (23, 33, 43).

3. The electrolysis system (21, 31, 41) according to claim 1 or 2, The electrolysis system comprises a cross-flow connection (18) connecting the undersides of the chambers (02, 03).

4. The electrolysis system (41) according to claim 1 or 2, in, The compensating connection (42) is partially connected to the cathode-side water connection (15) via a cross-flow connection (18) connecting the lower sides of the chambers (02, 03) or is connected to the lower side of the cathode chamber (03).

5. The electrolysis system (41) according to any one of claims 1 to 4, in, The operating pipeline (24, 34) leads to the anode side water connection (14); or The operating pipeline (44) leads to the anode side gas connection part (16).

6. The electrolysis system (21, 31) according to claim 1 or 2, in, The service line (24, 34) is led partially via a cross-flow connection (18) connecting the lower sides of the chambers (02, 03) to the anode-side water connection (14) or is connected to the lower side of the anode chamber (02).

7. The electrolysis system (21, 31, 41) according to any one of claims 1 to 6, in, According to provisions, the shutdown line (25, 35, 45) is interrupted during operation and flow is passed through in the shutdown state; and In particular, flow is passed through the operating lines (24, 34, 44) during operation and is interrupted in a stationary state.

8. The electrolysis system (21) according to any one of claims 1 to 7, in, According to provisions, in the shutdown state, fluid flows from the compensating connection (22) via the shutdown line (25) from top to bottom through the cathode chamber (03).

9. The electrolysis system (31, 41) according to any one of claims 1 to 7, in, The operation pipeline (44) or the second shutdown pipeline (35b) is led to the anode side gas connection part (16), According to regulations, in the shutdown state, the cathode chamber (03) flows from the compensating connection (32, 42) through the shutdown pipeline (35a, 45) from top to bottom, and the anode chamber (02) flows from top to bottom through the operating pipeline (44) or the second shutdown pipeline (35b).

10. The electrolysis system (21, 31) according to any one of claims 7 to 9, in, According to provisions, in the idle state, a flow from the cathode space (03) to the hydrogen separator (05) is present at least partially in the cathode-side water connection (15).

11. The electrolysis system (21) according to any one of claims 1 to 10, The electrolysis system comprises a purge circuit (26) which leads from the anode-side water connection (14) to the anode-side gas connection (16) and has a pump (13) and an ion exchanger (12).

12. The electrolysis system (21) according to claim 11, in, Provision is made that during operation there is a flow from the purification circuit (26) to the oxygen separator (04), and in a shutdown state there is a flow to the anode chamber (02); and / or According to the provisions, in the idle state, there is a flow in the anode-side water connection (14) from the anode space (02) to the oxygen separator (04).

13. Method for controlling an electrolysis system (21, 31, 41) according to any one of the preceding claims, in, During operation of the electrolysis system (21, 31, 41), a voltage is applied between the anode and the cathode, and a gas-water mixture flows from the associated chamber (02, 03) to the associated separator (04, 05) through the respective gas connection (16, 17), and water flows from the respective separator (04, 05) to the associated chamber (02, 03) through the associated water connection (14, 15), wherein a branch flow relative to the cathode side water connection (15) is caused by a pump, and the branch flow passes through the compensation connection (22, 32, 42) of the ion exchanger (12) and flows through the operating pipeline (24, 34, 44) to the anode side water circulation loop (06); and wherein, in a shutdown state of the electrolysis system (21, 31, 41), there is no voltage between the anode and the cathode, A flow is induced by a pump (13), the flow flowing from the cathode side water connection (15) through the compensation connection (22, 32, 42) of the ion exchanger (12) and through the shutdown pipeline (25, 35, 45) to the cathode side gas connection (17) and further to the cathode chamber (03).

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