Electrolytic cell system

Abstract

The present invention relates to an electrolytic cell system (10) comprising at least one electrolytic cell (20) having at least one steam inlet (41) and at least one off-gas outlet (38, 39), and a turbocharger (62) for compressing off-gas from the electrolytic cell (20). The turbocharger (62) comprises a drive fluid inlet, a drive fluid outlet, a compress fluid inlet, a compress fluid outlet, a compressor (13), and a turbine (12). The turbine (12) is configured to drive the compressor (13). The drive fluid outlet of the turbocharger (62) is fluid-connected to at least one steam inlet (41) of the electrolytic cell (20). At least one off-gas outlet (38, 39) of the electrolytic cell (20) is fluid-connected to the compress fluid inlet of the turbocharger (62). The system (10) may further comprise a steam source fluid-connected to the drive fluid inlet of the turbocharger (62) for powering the turbine (12) using pressurized steam.

Description

Technical Field

[0001] The present invention relates to an electrolyzer system for producing compressed hydrogen, preferably a solid oxide electrolyzer system.

Background Art

[0002] It is well known that an electrolyzer cell (also known as a regenerative fuel cell) can be used to convert water into hydrogen and oxygen. This process requires an electrical supply but is a relatively simple process.

[0003] Oxygen is a valuable resource, but hydrogen is the main focus of the present invention. This is because it is generally known that the collection of hydrogen and its subsequent storage and / or distribution are difficult or costly, and yet when achieved, the resulting compressed hydrogen can be very valuable as a fuel that can contribute to achieving a net zero or decarbonization goal by recombining with oxygen either by combustion or by using an electrolysis reaction within a fuel cell.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The most well-known hydrogen storage solutions are complex and costly because the size of hydrogen particles is small and they tend to escape through the walls of conventional containers, and also because hydrogen particles need to be compressed to a high pressure and / or the temperature of hydrogen particles needs to be reduced to a very low temperature in order to liquefy hydrogen. As a result, both hydrogen storage containers and filling equipment are expensive to manufacture and use, particularly with respect to the processes and equipment required to compress or liquefy hydrogen that is ready for such storage or transportation. For example, many hydrogen storage solutions require extremely low temperatures known as cryogenic temperatures. Furthermore, most hydrogen storage solutions require a large amount of energy supplied from the outside in order to operate an electrolyzer and to generate the high pressures and low temperatures required to liquefy (or sufficiently compress) hydrogen that is ready to fill a suitable storage container.

[0005] The present invention aims to provide a system for hydrogen compression that is less dependent on external energy demand. [Means for solving the problem]

[0006] According to a first aspect of the present invention, (a) at least one electrolytic cell having at least one vapor inlet and at least one off-gas outlet, (b) A turbocharger for compressing the off-gas from the electrolytic cell An electrolytic cell system comprising, A turbocharger comprises a drive fluid inlet, a drive fluid outlet, a compressor fluid inlet, a compressor fluid outlet, a compressor, and a turbine. The turbine is configured to drive the compressor. The turbocharger's drive fluid outlet is fluid-connected to at least one vapor inlet of the electrolytic cell. An electrolytic cell system is provided in which at least one off-gas outlet of the electrolytic cell is fluidly connected to the compressed fluid inlet of a turbocharger.

[0007] In this way, it is possible to achieve higher supply pressures while enabling the hydrogen generation system to operate at or near atmospheric pressure.

[0008] In a typical configuration, the electrolytic cell system includes a steam source, such as a steam generator. The steam source or steam generator is fluidly connected to the turbocharger's drive fluid inlet to power the turbine using pressurized steam. The steam can be supplied by a steam generator or an external steam source and is supplied at a pressure exceeding the electrolytic cell's operating pressure. The higher steam pressure allows the steam to power the turbocharger.

[0009] After supplying power to the turbine, the steam exits the turbine via the drive fluid outlet and enters the electrolytic cell via the steam inlet, becoming at least a partial water source for the electrolytic cell.

[0010] In some embodiments, the electrolytic cell system includes a heat exchanger adapted to cool the off-gas before it enters the compressor.

[0011] In some embodiments, the electrolytic cell system includes a collection chamber for collecting water from the off-gas. This may be before, during, or after compression by the turbocharger.

[0012] In some embodiments, the compressed fluid outlet of the turbocharger is fluidically connected to a collection chamber (i.e., the collection chamber is located downstream of the turbocharger).

[0013] In some embodiments, the collection chamber has a fluid input section that is fluidly connected to the compressed fluid outlet of the turbocharger.

[0014] In some embodiments, the collection chamber has a compressed fluid outlet that is fluid-connected to the compressed fluid inlet of the compressor (i.e., the collection chamber is located upstream of the turbocharger).

[0015] In some embodiments, the steam generator is fluidically connected to at least a collection chamber. This allows the collected water to supply at least partially water to the steam generator. The steam generator can then serve as a steam source for powering a turbine using steam at least partially obtained from the water in the collection chamber. For example, the electrolytic cell system may further include a steam generator, the collection chamber being fluidly connected to the outlet of the steam generator to collect condensate from the steam as it exits the steam generator.

[0016] In this invention, the steam generated as a result of a steam generator (which is at a high pressure relative to the off-gas pressure at the off-gas outlet and can therefore be called "high-pressure" steam) can be supplied to the turbine of a turbocharger. The energy present in the high-pressure steam is used to rotate the turbine. The turbine is then connected to a compressor. The turbine then powers the compressor, for example, by driving a compressor wheel or other mechanical compression device. The compressor can then compress an off-gas gas, such as hydrogen, which is at a relatively lower pressure than the generated steam before compression and can therefore be called "low-pressure off-gas." This low-pressure off-gas is produced as a result of an electrolytic reaction in an electrolytic cell.

[0017] Off-gas can be called "high-pressure off-gas" because it is compressed to a relatively higher pressure than low-pressure off-gas. This high-pressure off-gas can then be collected in storage containers or otherwise distributed for downstream use.

[0018] Furthermore, using an optional collection chamber, water condensed from the low-pressure off-gas before, during, or after the off-gas is compressed by the turbocharger can be collected in the collection chamber and then converted back into steam, which is then used to power the turbine and again supplied to the electrolytic cell to become the source fluid (water) for the electrolytic reaction within the electrolytic cell.

[0019] This recirculation of wastewater (from off-gas) improves system efficiency by eliminating the need to replace the entire supply water after the water has passed through the electrolytic cell, and instead allows the portion of water that was not broken down by the electrolytic cell to be recirculated back into the electrolytic cell.

[0020] In some embodiments, the electrolytic cell operates at a pressure above atmospheric pressure but below 0.5 barg (gauge pressure).

[0021] In other embodiments, the electrolyzer operates at a pressure of 0.5 barg (gauge pressure) or more. Preferably, it operates at a pressure of 3 barg or less, more preferably 2 barg or less.

[0022] In some embodiments, the system comprises a pump configured to deliver water to a steam generator. In some embodiments, the pump is configured to deliver water condensed from the off-gas from the electrolyzer.

[0023] In some embodiments, a collection chamber is provided after the steam generator to collect condensate from the steam as the steam exits the steam generator. This collection chamber can be the second collection chamber of the system.

[0024] In some embodiments, the electrolyzer comprises at least one electrolyzer cell. The electrolyzer cell is also known as a fuel cell or a regenerative fuel cell.

[0025] Typically, at least one electrolyzer cell is part of a stack of electrolyzer cells. One or more stacks may be present in the electrolyzer.

[0026] The fuel cell may comprise an anode, a cathode, and an electrolyte. However, some stacks may further comprise dummy cells (e.g., without an electrolyte).

[0027] In some embodiments, the electrolyzer cell or each electrolyzer cell has an operating stack temperature exceeding 400°C.

[0028] In some embodiments, at least one electrolyzer cell is a solid oxide electrolyzer cell, i.e., the electrochemically active region is a solid oxide. Solid oxide electrolysis cells (SOECs) typically operate in the range of 400°C to 900°C (or for some chemicals 400°C to 700°C), or more specifically in the temperature range of 450°C to 650°C. Such electrolyzer cells are sometimes referred to as intermediate temperature solid oxide electrolyzer cells, i.e., IT-SOECs.

[0029] There are many possible forms of SOECs that utilize different electrochemically active electrolyte chemistry properties. For example, three well-known electrolyte materials are yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), and gadolinium-doped ceria (GDC or CGO).

[0030] Due to the SOEC temperature (typically exceeding 400°C), hydrogen is always emitted as a mixture with vapor, and therefore, it was considered difficult to compress the emitted hydrogen without first passing it through a drying process. However, the inventors realized that the drying step could be automated because as the mixture is compressed, water condenses from the mixture, leaving substantially pure hydrogen for collection and distribution or use.

[0031] In some embodiments, the electrolytic cell system comprises a high-temperature electrolytic cell having an operating stack temperature of 750°C to 1100°C.

[0032] The present invention further, (a) at least one electrolytic cell having an operating pressure and having at least one vapor inlet and at least one off-gas outlet, (b) A turbocharger for compressing off-gas from an electrolytic cell, comprising a drive fluid inlet, a drive fluid outlet, a compress fluid inlet, a compress fluid outlet, a compressor, and a turbine. An operating method for an electrolytic cell system comprising, Steam at a supply pressure higher than the operating pressure of the electrolytic cell is supplied to the turbocharger's drive fluid inlet to power the turbine, and the turbine is configured to drive the compressor. The turbocharger's drive fluid outlet is fluid-connected to at least one vapor inlet of the electrolytic cell, thereby the vapor then exits the turbine and enters the electrolytic cell at a reduced pressure compared to its supply pressure. The present invention provides an operating method in which at least one off-gas outlet of the electrolytic cell is fluidly connected to the compression fluid inlet of the turbocharger, thereby sending the off-gas from the electrolytic cell to the turbocharger for compression by the turbocharger.

[0033] In some embodiments, steam is supplied by a steam generator, which is part of an electrolytic cell system.

[0034] The electrolytic cell system may be an electrolytic cell system as defined above.

[0035] In some embodiments, the method comprises at least one collection chamber for collecting distilled water or condensed water.

[0036] In some embodiments, the water collected from one or more collection chambers provides at least a partial water supply for a steam generator, which is a source of steam for powering a turbine.

[0037] In some embodiments, the electrolytic cell operates at a pressure above atmospheric pressure but below 0.5 barg (gauge pressure).

[0038] In some embodiments, the electrolytic cell operates at a pressure of 0.5 barg or higher, but 3 barg or lower.

[0039] In some embodiments, the heat from the off-gas from the electrolytic cell is recovered by at least one heat exchanger before it enters the compressor.

[0040] In some embodiments, the method includes the step of collecting water condensed as a result of heat recovery by a heat exchanger.

[0041] This cooled condensed water can be recycled back into a water source for the steam generator.

[0042] In some embodiments, hydrogen is discharged from a first side of the electrolytic cell (or from the electrolytic cell or the first side of each electrolytic cell), and oxygen is discharged from a second side of the electrolytic cell (or from the electrolytic cell or the second side of each electrolytic cell), resulting in hydrogen and oxygen outputs from the electrolytic cell. Oxygen and hydrogen may be collected so that both hydrogen and oxygen are beneficially produced and collected, or only hydrogen (or only oxygen) may be collected.

[0043] Typically, the hydrogen output is on the cathode side of the electrolytic cell (or the electrolytic cell of the electrolytic cell or each individual electrolytic cell). Therefore, hydrogen is discharged on the cathode side.

[0044] Typically, oxygen is discharged at the anode side of the electrolytic cell (or the electrolytic cell of the electrolytic cell or each electrolytic cell).

[0045] In some embodiments, the electrolytic cell has an operating temperature above 200°C, above 300°C, or more commonly above 400°C. Because the operating temperature of such electrolytic cells is well above 100°C, hydrogen is always discharged as a mixture with vapor. As described above, it was initially thought difficult to compress such off-gas without passing the off-gas through a drying process. However, the inventors realized that the drying step could be automated because as the mixture is compressed, water condenses from the mixture, leaving substantially pure hydrogen for collection and distribution or use.

[0046] In some embodiments, the off-gas released from the electrolytic cell at a first pressure passes through the compressor so as to exit the compressor at a relatively high pressure.

[0047] In some embodiments, there are two off-gas systems, and only one of the off-gas systems passes through the turbocharger's compressor.

[0048] In some embodiments, the off-gas being compressed is hydrogen-enriched steam.

[0049] In some embodiments, waste heat from the electrolytic cell acts as at least a partial heat source for the steam generator. In some embodiments, the system instead, or in addition to, includes one or more external heat sources or power supplies, or one or more heaters, to power the steam generator.

[0050] In some embodiments, heat from exhaust steam (the second supply off-gas of the electrolytic cell) can be recovered via a heat exchanger and used to heat the steam generator.

[0051] In some embodiments, the system is configured such that the steam exiting the turbine passes through a third heater and / or a heat exchanger that extracts heat from the electrolytic cell. Alternatively, or in addition to this, the heat from the electrolytic cell may be recirculated through the heat exchanger to a swept-flow fluid and / or a water or steam source for the electrolytic cell, i.e., a fluid source for the electrolytic cell. In some embodiments, one or more heat exchangers connect their heat directly to the body of the electrolytic cell. These configurations may help maintain a desired operating temperature for the electrolytic cell.

[0052] In some embodiments, the steam generator is configured such that the steam exiting the steam generator is at a higher pressure than the water entering the steam generator. Thus, in some embodiments, the system is configured such that the steam from the steam generator is at a relatively higher pressure than the off-gas from the electrolytic cell, and the steam from the steam generator passes through a turbine before entering at least one electrolytic cell, and the energy from the steam pressure rotates the turbine, which in turn rotates a compressor, thereby pressurizing the off-gas.

[0053] In this embodiment, as the steam exits the turbine through the drive fluid outlet, its pressure is reduced by the turbine, allowing it to enter the electrolytic cell at a relatively lower pressure than the pressure at which it enters the turbine. This ensures that the internal pressure of the electrolytic cell is maintained at a pressure close to atmospheric pressure (e.g., about 0 barg to 3 barg, preferably 0.5 barg to 1 barg, more preferably about 0.5 barg), thereby simplifying the structure of the electrolytic cell.

[0054] In some embodiments, a collection chamber collects condensed water from the currently pressurized off-gas flow (after or as it passes through the compressor), and the system or compressor has a pressurized off-gas outlet for distributing the pressurized off-gas (usually hydrogen) elsewhere, for example, to a pressure vessel or delivery pipeline for further compression.

[0055] In some embodiments, water collected in the collection chamber from the pressurized off-gas passes through a heat exchanger in the steam generator.

[0056] In some embodiments, water is vaporized in a heat exchanger or steam generator to form steam at a pressure exceeding atmospheric pressure.

[0057] In some embodiments, water condenses from the off-gas mixture (usually hydrogen and steam) by cooling the off-gas mixture, and in other embodiments, by pressurizing the mixture, although condensation may occur in a combination of both. It should also be noted that collection and / or recirculation of the condensed water is optional.

[0058] In some embodiments, a second collection chamber is provided after the steam generator to collect condensates or unevaporated water from the steam as it leaves the steam generator.

[0059] In some embodiments, the condensate is recirculated, for example, through a steam generator via a pump.

[0060] In some embodiments, the steam exiting the steam generator is superheated steam.

[0061] In other embodiments, the steam is then superheated by an additional heater or heat exchanger before being supplied to the turbocharger turbine. It is preferable to supply superheated steam to the turbine to increase its efficiency.

[0062] Here, the present invention will be described in more detail, merely as an example, with reference to the attached drawings. [Brief explanation of the drawing]

[0063] [Figure 1] This is a schematic diagram of a first embodiment of the electrolytic cell system according to the present invention. [Figure 2] This is a schematic diagram of a typical electrolytic cell in an electrolytic cell system, where multiple cells can be stacked. [Figure 3] This is a schematic diagram of a second embodiment of the electrolytic cell system according to the present invention. [Figure 4] This is a schematic diagram of a third embodiment of the electrolytic cell system according to the present invention. [Figure 5] This is a schematic diagram of a fourth embodiment of the electrolytic cell system according to the present invention. [Modes for carrying out the invention]

[0064] By coupling the turbocharger 62 to the electrolytic cell, the electrolytic cell 20 can be operated at near atmospheric pressure (but preferably at a pressure higher than atmospheric pressure), while simultaneously generating off-gas (particularly hydrogen) at significantly higher pressures. This means that a simpler electrolytic cell structure, less susceptible to leakage, can be used.

[0065] First, referring to Figure 1, a first embodiment of the electrolytic cell system 10 is shown. The system uses steam generated by the steam generator 61 and the electrolytic cell 20 to power the turbocharger 62, and at the same time generates hydrogen for compression by the turbocharger 62.

[0066] In this embodiment, water (preferably deionized water from a deionized water source 18) is pumped through a first heat exchanger 19 at a high pressure such as 10 barg to 15 barg. A pump 14 can be used for this purpose. The first heat exchanger 19 is supplied with heat from an external heat source 17 (which may be at least partially heat from the electrolytic cell 20) via external heat in line 51, and this heat is used to convert the water into high-pressure steam. Excess heat 52 is generated, which may be used to heat the electrolytic cell 20 or in another process. The high-pressure steam then exits the heat exchanger 19, passes through a pressure regulator 16, and enters a second heat exchanger 69 through an optional collection chamber 63. This second heat exchanger is also optional, but may be used to superheat the steam if it has not yet been superheated by the first heat exchanger 19.

[0067] It is generally known that steam, when it rises to a sufficiently high pressure, will condense at least partially into water. This is because the evaporation temperature of water decreases with increasing pressure. Therefore, condensed water can be collected by placing a collection chamber 63 between the first heat exchanger 19 and the second heat exchanger 69.

[0068] In this embodiment, the collection chamber 63 is configured to return water through the first heat exchanger 19 via a condensate recovery line (or recirculation line) 64 that sends water back through the pump 14.

[0069] Superheating steam is a well-known process in the art. This process involves raising the temperature of the steam above its saturation point at a given pressure. This is done to reduce the risk of damage or corrosion to the internal surfaces of the system through which the steam passes, such as the turbine blades of the turbocharger 62 or the internal surfaces of the electrolytic cell. In particular, it protects the cathode of the electrolytic cell, which may crack if exposed to liquid water.

[0070] In the embodiment shown in Figure 1, superheated high-pressure steam passes through the turbine 12 of a turbocharger 62, which is connected to a compressor 13. The energy present in the steam due to the steam pressure is used to rotate the turbine 12, and as a result, also powers the compressor 13. Thus, power is supplied to the turbocharger 62 by passing through the turbine 12. However, this reduces the pressure and / or temperature of the superheated steam so that the steam can then pass through an optional third heat exchanger 70 to raise its temperature to the operating temperature of the electrolytic cell 20 before entering the electrolytic cell 20 if necessary.

[0071] The compressor 13 may be a centrifugal compressor directly connected to the shaft of the turbine (steam expander) 12, or another type of mechanically driven compressor. For example, the compressor 13 can take the form of a reciprocating compressor, where the turbine shaft drives a cam to produce reciprocating motion. Furthermore, the compressor 13 may be powered only partially by the turbine 12, and "supplementary" power may be supplied to increase the compression ratio.

[0072] When the vapor enters the electrolytic cell 20, which is operated by an external power source, it is electrolyzed within the electrolytic cell cells 11 of the electrolytic cell to produce hydrogen and oxygen. These gases can be discharged from the electrolytic cell as a mixture of hydrogen and vapor, with the hydrogen being discharged along the cathode side of the electrolytic cell along the residual vapor. The oxygen, on the other hand, is discharged from the anode side of the electrolytic cell and is therefore separated from the mixture.

[0073] The exhaust gas from the electrolytic cell is also known as off-gas.

[0074] Typically, the electrolytic cell 20 operates at a pressure above atmospheric pressure but below 0.5 barg (gauge pressure), and therefore the off-gas is also discharged at that pressure. This pressure is too low to store or distribute, particularly with respect to hydrogen, so the present invention is configured to send that hydrogen to the compressor 13 of the turbocharger 62.

[0075] In this embodiment, the electrolytic cell 20 operates at a pressure above atmospheric pressure but below 0.5 barg. In other embodiments, the electrolytic cell 20 may operate at a pressure of 0.5 barg or higher, although in typical commercially available electrolytic cells, the operating pressure is maintained at a level of 3 barg or less, or more generally, 2 barg or less.

[0076] The mixture of hydrogen and excess vapor exiting the cathode of the electrolytic cell 20 can be called "moist hydrogen." This mixture exits the electrolytic cell 20 as described above and passes through the compressor 13 of the turbocharger 62. Since the compressor 13 is powered at least in part by its connection to the turbine 12, the passage of its off-gas through the compressor 13 compresses the moist hydrogen and increases its pressure.

[0077] After being pressurized by the compressor 13, the pressurized mixture passes through a further optional collection chamber 15, fluid-connected to the compressed fluid outlet of the turbocharger 62, to collect condensate from the mixture before the off-gas is stored or used downstream 21. In this embodiment, the collected water can then be sent back to the first heat exchanger 19 via a further condensate recovery line (or recirculation line) 57, which similarly sends the water back through the pump 14.

[0078] This additional optional collection chamber will hereafter be referred to as the first collection chamber 15, and the aforementioned collection chamber 63 may be referred to as the second collection chamber 63.

[0079] Therefore, pressurized steam can be used to operate the turbocharger 62 and compress the off-gas (preferably hydrogen off-gas) released as a by-product of the electrolytic reaction in the electrolytic cell. Furthermore, the turbocharger 62 can optionally condense the steam in the mixture to dry the hydrogen that is ready for use elsewhere (or by the electrolytic cell if it can also be used as a fuel cell to generate electricity rather than for regeneration). The solid oxide fuel cell manufactured by the applicant's Ceres Power (RTM) is thus bidirectional.

[0080] The use of this steam pressure, particularly the recirculation of water, increases the overall efficiency of the electrolytic cell system 10. If the heat for the steam generator is available as a waste heat source, the system 10 can reuse that heat, making it even more efficient.

[0081] Such a configuration is particularly advantageous when the pressurized steam source is readily available, for example, as a by-product (or excess) of another industrial process, such as in an oil refinery or power plant, or from a hot water source. In such cases, the steam generator 61 is absent and simply replaced by the steam source. The recovered water may be recycled to an external steam supply system or simply discarded.

[0082] The present invention can reduce the need for additional compression stages to pressurize off-gas (hydrogen) for purposes such as storage, downstream use, for example, within the system (when used as a fuel cell rather than for regeneration purposes), or for external purposes. This partial compression also improves downstream processing requirements and can result in a simpler downstream system design.

[0083] Depending on the constraints in the design selection and / or operating requirements, different variables can be varied to control pressure at different points. Relevant factors related to the control strategy include: • Ability to control the pressure of the steam inlet It is desirable to maintain a constant internal electrolytic cell pressure. For example, efficiency may decrease if the pressure deviates from the optimal pressure. • The expansion ratio of the turbocharger expander and / or the turndown ratio of the compressor. For example, efficiency may decrease from optimal conditions, or this may be fixed in "off-the-shelf" turbochargers. • The required level of downstream compression, which may affect the desired off-gas pressure. • The utilization rate and the relative flow rate (and therefore relative pressure) of water vapor to hydrogen are affected by the proportion of water vapor that is electrolyzed into hydrogen and oxygen.

[0084] The table below shows exemplary operating conditions and benefits / considerations when controlling one variable by modifying another variable. [Table 1]

[0085] In some embodiments, the internal pressure of the electrolytic cell has an optimal level (e.g., the maximum pressure before leakage becomes unacceptable). In such cases, the off-gas pressure can be adjusted by changing the steam inlet pressure and the expansion ratio of the turbocharger expander (and the compressor turndown ratio).

[0086] For example, if the steam pressure is at a constant level, the turbocharger must reduce it to the desired internal pressure of the electrolytic cell, and the amount of this pressure reduction defines the amount of off-gas compression (based on the compressor's turndown ratio).

[0087] In this first embodiment, the amount of deionized water from the external source 18 can be substantially reduced, and only a portion of the steam passing through the electrolytic cell is converted to hydrogen and oxygen, thus allowing the water to be recirculated through the electrolytic cell system 10 by recovering the remaining water through condensation in the turbocharger 62 (due to a decrease in temperature and an increase in pressure). Similarly, any liquid water produced or remaining after pressurizing the steam in the first heat exchanger 19 (e.g., steam generator 61) can be collected, recirculated, and returned to the first heat exchanger 19 where it is heated to generate more steam at high pressure.

[0088] Referring next to Figure 2, the basic structure and operation of a typical electrolytic cell 11 within the electrolytic cell 20 are shown by referring to one fuel / electrolytic cell 11 in the stack. Note that the electrolytic cell 20 includes other auxiliary components related to the cell 11. These include heat exchangers, valves, and sensors. Figure 5 shows a partially enlarged electrolytic cell 20 with exemplary auxiliary components.

[0089] The electrolytic cell 11 comprises an anode 33, a cathode 34, and an electrolyte 35. Such a structure of the electrolytic cell 11 is well known in the art. Water (here in the form of vapor 43 from a vapor source such as a vapor generator) passes over the cathode 34 via an inlet 41, and hot air 42 passes over the anode 33 via an inlet 41. To power the electrolytic cell 20, a current / voltage is applied across both ends of the electrolytic cell 11 via electrical terminals / connections 36, 37 on the anode and cathode sides of the electrolytic cell 11. These terminals may be positioned adjacent to each other on one side of the stack, for example by extending one terminal using a busbar. As a result, an electrolytic reaction occurs across the electrolyte 35, and oxygen ions pass across the electrolyte 35 from the cathode 34 to the anode 33, thereby decomposing some of the vapor into hydrogen on the cathode side and oxygen on the anode side of the electrolytic cell 11.

[0090] Oxygen can be extracted via an airflow or sweep flow generated by high-temperature air 42 to discharge oxygen as oxygen-enriched air from the off-gas outlet 38 on the anode side of the electrolytic cell 11. Hydrogen can be extracted and discharged from another off-gas outlet 39 on the cathode side of the electrolytic cell 11. This off-gas may contain water vapor, and the conversion of water vapor to oxygen and hydrogen usually occurs only with respect to a portion of the supplied vapor. Thus, the hydrogen is discharged as "moist" hydrogen. As a result, the vapor exiting the cathode side is hydrogen-rich, and the air exiting the anode side is oxygen-rich. Due to the operating temperature of the electrolytic cell 11 (typically above 400°C in the case of SOEC), these off-gas will be at a temperature similar to the operating temperature of the electrolytic cell 11.

[0091] While such operating characteristics of SOECs are well known in the art, the heat from the off-gas is beneficial to the present invention because it can be usefully utilized by the electrolytic cell system 10, for example, to supply at least a portion of the heat to the steam generator 61, rather than being wasted.

[0092] Referring now to Figure 3, a second embodiment of the present invention is shown. As can be seen from the figure, this embodiment is schematically shown in the same form as the embodiment in Figure 1, except that the heat exchanger 69 is omitted. This embodiment also uses steam generated by the steam generator 61 to power the electrolytic cell 62. The deionized water, as in this case as well, passes through the first heat exchanger 19 in the steam generator 61 at high pressure and high temperature, but in this embodiment, the temperature and pressure are exemplary instead of 9 barg and 90°C. This is similarly driven by the pump 14. Furthermore, the heat exchanger 19 may be supplied with heat from an external source 17, which is used to vaporize the high-pressure water into high-pressure steam. However, in this embodiment, this first heat exchanger 19 achieves the superheating of the steam. In one example, the steam is at a temperature and pressure of 250°C at 9 barg, but similar effects can be obtained by using alternative temperatures and pressures instead. The second heat exchanger 69 in Figure 1 is no longer necessary since the steam has already been superheated, and is therefore not shown to be present.

[0093] In each of these embodiments, additional pressure regulators, pressure sensors, and temperature sensors may be provided. These may allow the system to be monitored by a control system and adjusted to avoid excessive peak pressure or excessively low pressure.

[0094] Referring now to Figure 4, a third embodiment of the electrolytic cell system 10 is shown. This is similar to the embodiment in Figure 3, except that the second collection chamber is eliminated, as the steam generator 61 is adapted to operate in such a way that little or no liquid water remains at the outlet of the steam generator 61. Since the system operates in the same manner as in Figures 1 and 3 in other respects, no further explanation is needed for this embodiment.

[0095] Next, referring to Figure 5, a fourth embodiment of the electrolytic cell system 10 is shown, which includes additional auxiliary components within the electrolytic cell 20. Such components may be present in the electrolytic cell 20 in the systems of Figures 1, 3, and 4 to cool and dry the off-gas before compression.

[0096] The embodiment in Figure 5, similar to the embodiments in Figures 1, 3, and 4, uses steam generated by the steam generator 61 to power the electrolytic cell 20. The additional components shown are for removing at least some of the water before the off-gas is compressed. This reduces the amount of water that condenses inside the compressor, which can negatively affect performance and potentially damage the compressor.

[0097] As described above, the steam passes through the electrolysis cell 11 and other auxiliary components, the electrolysis cell 20', and some of the steam is decomposed into oxygen and hydrogen, and the electrolysis cell 20' outputs at least moist hydrogen (a mixture of steam and hydrogen) for compression by the turbocharger 62. However, instead of being discharged directly to the compressor 13 of the turbocharger 62, the discharged moist hydrogen is supplied to the heat exchanger 71 through the supply line 30, where it is partially cooled. The excess heat can be used to heat the water source that supplies the steam generator. In this case, the heat exchanger 71 is a regenerative heat exchanger. It is then further cooled by passing through a second heat exchanger 68, where the water condenses. This condensed water can be collected in the collection chamber 15. The hydrogen, in an at least partially dried state, is supplied to the compressor 13 of the turbocharger 62. Further water collection into the collection chamber 15 is performed to capture condensate after compression, and then sent for storage or downstream use 21.

[0098] Meanwhile, the water condensed from the mixture is supplied to pump 14 to return to the cycle. For this purpose, the water is mixed with the necessary resupply water from water source 18 and then passes through pump 14. Pump 14 returns the water through regenerative heat exchanger 71 to preheat the water, and then passes the water again through first heat exchanger 19 to further heat the water and convert it into steam. A heat source 17 is also provided. This generates steam, which is pressurized and passes through turbine 12 of turbocharger 62 to drive compressor 13.

[0099] As the pressurized steam passes through the turbine 12 of the turbocharger 62, the energy of the pressurized steam is used to rotate the turbine 12 connected to the compressor 13, as described above with respect to Figures 1 and 3.

[0100] It should be understood that a second off-gas (in this case, oxygen-enriched air) is discharged through a second supply line (not shown).

[0101] Heat exchangers in the diagram that perform opposite operations (i.e., heating / cooling) can be combined as two sides of a single heat exchanger to increase the temperature difference and therefore operate more efficiently.

[0102] Accordingly, the present invention is described above merely as an example with reference to the accompanying drawings. It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the scope of the appended claims. For example, features described as part of one embodiment can be used in another embodiment to produce yet another embodiment. Accordingly, the present invention is intended to encompass modified and varied forms that fall within the scope of the appended claims. For example, although the above description focuses on H2O electrolysis, it is applicable to CO2 electrolysis in which CO is produced at the cathode and O2 is produced at the anode. In such an embodiment, CO2 replaces the vapor input and CO replaces the hydrogen-enriched vapor output.

Claims

1. (a) at least one electrolytic cell having at least one vapor inlet and at least one off-gas outlet, (b) A turbocharger for compressing the off-gas from the electrolytic cell and An electrolytic cell system comprising, The turbocharger comprises a drive fluid inlet, a drive fluid outlet, a compressor fluid inlet, a compressor fluid outlet, a compressor, and a turbine. The turbine is configured to drive the compressor, The drive fluid outlet of the turbocharger is fluidly connected to the at least one vapor inlet of the electrolytic cell. An electrolytic cell system wherein the at least one off-gas outlet of the electrolytic cell is fluidly connected to the compressed fluid inlet of the turbocharger.

2. The electrolytic cell system according to claim 1, further comprising a steam source fluidly connected to the drive fluid inlet of the turbocharger for supplying power to the turbine using pressurized steam.

3. The electrolytic cell system according to claim 1 or 2, further comprising a heat exchanger adapted to cool the off-gas before it enters the compressor.

4. The electrolytic cell system according to any one of claims 1 to 3, further comprising a collection chamber for collecting water from the off-gas.

5. The electrolytic cell system according to claim 4, wherein the collection chamber has a fluid input section fluidly connected to the compressed fluid outlet of the turbocharger.

6. The electrolytic cell system according to claim 4 or 5, wherein the collection chamber has a compressed fluid outlet fluid-connected to the compressed fluid inlet of the compressor.

7. The electrolytic cell system according to any one of claims 4 to 6, wherein a steam generator is fluidly connected to at least the collection chamber.

8. The electrolytic cell system according to any one of claims 1 to 7, further comprising a steam generator, wherein a collection chamber is fluidly connected to the outlet of the steam generator to collect condensate from the steam as the steam exits the steam generator.

9. The electrolytic cell system according to any one of claims 1 to 8, wherein the electrolytic cell comprises at least one stack of electrolytic cell cells.

10. The electrolytic cell system according to any one of claims 1 to 9, wherein each electrolytic cell has an operating stack temperature exceeding 400°C.

11. The electrolytic cell system according to claim 10, wherein the electrolytic cell is a solid oxide electrolytic cell.

12. (a) at least one electrolytic cell having an operating pressure and having at least one vapor inlet and at least one off-gas outlet, (b) A turbocharger for compressing off-gas from the electrolytic cell, comprising a drive fluid inlet, a drive fluid outlet, a compressible fluid inlet, a compressible fluid outlet, a compressor, and a turbine. An operating method for an electrolytic cell system comprising, Steam at a supply pressure higher than the operating pressure of the electrolytic cell is supplied to the drive fluid inlet of the turbocharger to power the turbine, and the turbine is configured to drive the compressor. The drive fluid outlet of the turbocharger is fluidly connected to the at least one steam inlet of the electrolytic cell, thereby the steam then exits the turbine and enters the electrolytic cell at a reduced pressure compared to its supply pressure. An operating method wherein the at least one off-gas outlet of the electrolytic cell is fluidly connected to the compressible fluid inlet of the turbocharger, thereby sending the off-gas from the electrolytic cell to the turbocharger for compression by the turbocharger.

13. The method according to claim 12, wherein the steam is supplied by a steam generator which is part of the electrolytic cell system.

14. The method according to claim 12 or claim 13, wherein the electrolytic cell system is the system described in any one of claims 1 to 11.

15. The method according to any one of claims 12 to 14, comprising at least one collection chamber for collecting distilled water or condensed water.

16. The method according to claim 15, wherein the water collected from one or more collection chambers provides at least a partial water supply for a steam generator which is a source of steam for powering the turbine.

17. The method according to any one of claims 12 to 16, wherein the electrolytic cell operates at a pressure greater than atmospheric pressure but less than 0.5 barg (gauge pressure).

18. The method according to any one of claims 12 to 17, wherein the electrolytic cell operates at a pressure of 0.5 barg or more but 3 barg or less.

19. The method according to any one of claims 12 to 18, wherein the heat of the off-gas from the electrolytic cell is recovered by at least one heat exchanger before it enters the compressor.

20. The method according to claim 19, further comprising the step of collecting water condensed as a result of heat recovery by the heat exchanger.

21. The method according to any one of claims 12 to 19, wherein hydrogen is discharged from the first side of the electrolytic cell and oxygen is discharged from the second side of the electrolytic cell to produce hydrogen output and oxygen output from the electrolytic cell.

22. The method according to any one of claims 12 to 21, wherein the off-gas released from the electrolytic cell at a first pressure passes through the compressor so as to exit the compressor at a relatively high pressure.

23. The method according to claim 22, wherein there are two off-gases, and only one of the off-gases passes through the compressor.

24. The method according to any one of claims 12 to 23, wherein heat from the discharged steam of the electrolytic cell is recovered via the heat exchanger and used to heat the steam.

25. The method according to any one of claims 12 to 24, wherein the steam exiting the turbine passes through a heater and / or a heat exchanger that extracts heat from the electrolytic cell.

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