ELECTROLYZER CELL SYSTEMS AND METHOD OF OPERATING THEREOF BY WATER COOLING OF SYSTEM EXHAUST

Description

FIELD

Aspects of the present invention relate to electrolyzer cell systems, and more particularly, to solid oxide electrolyzer cell systems and methods of operating thereof that include water cooling of system exhaust.

BACKGROUND

In a solid oxide electrolyzer cell (SOEC), a positive potential is applied to the oxygen electrode side of the cell and oxygen ions are transported from the fuel electrode side to the oxygen electrode side. During SOEC operation, water (e.g., steam) is reduced (H₂O+2e→O²⁻+H₂) to form H₂ gas and O²⁻ ions, the O²⁻ ions are transported through the solid electrolyte, and then oxidized (e.g., by an air inlet stream) on the oxygen electrode side (O²⁻ to O₂) to produce molecular oxygen (e.g., oxygen enriched air).

SUMMARY

According to various embodiments, an electrolyzer cell system includes a stack of electrolyzer cells located in a hot box and configured to generate a main product stream comprising hydrogen and steam, and an oxygen exhaust stream; a steam source fluidly connected to the stack and configured to provide a steam inlet stream to the stack; at least one product conduit fluidly connected to the stack and configured to receive the main product stream; and a water injector configured to provide liquid water into the main product stream in the at least one product conduit.

According to various embodiments, a method of operating an electrolyzer cell system includes providing a steam inlet stream to a stack of electrolyzer cells, generating a main product stream containing hydrogen and steam, and an oxygen exhaust stream in the stack, and providing liquid water into the main product stream to cool the main product stream.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate example embodiments of the invention, and together with the general description given above and the detailed description given below, serve to explain the features of the invention.

FIG. 1A is a schematic view of an electrolyzer cell system, according to a first embodiment of the present disclosure.

FIG. 1B is a schematic view of hot box components of the electrolyzer cell system of FIG. 1A according to the first embodiment of the present disclosure.

FIG. 2 is a schematic view of an electrolyzer cell system, according to a second embodiment of the present disclosure.

FIG. 3 is a schematic view of an electrolyzer cell system, according to a third embodiment of the present disclosure.

FIG. 4 is a schematic view of an electrolyzer cell system, according to a fourth embodiment of the present disclosure.

DETAILED DESCRIPTION

As set forth herein, various aspects of the disclosure are described with reference to the exemplary embodiments and/or the accompanying drawings in which exemplary embodiments of the invention are illustrated. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments shown in the drawings or described herein. It will be appreciated that the various disclosed embodiments may involve particular features, elements or steps that are described in connection with that particular embodiment. It will also be appreciated that a particular feature, element or step, although described in relation to one particular embodiment, may be interchanged or combined with alternate embodiments in various non-illustrated combinations or permutations.

The various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References made to particular examples and implementations are for illustrative purposes and are not intended to limit the scope of the invention or the claims.

Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, examples include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about” or “substantially” it will be understood that the particular value forms another aspect. In some embodiments, a value of “about X” may include values of +/−1% X. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

Solid oxide electrolyzer cells (SOEC) produce hydrogen and oxygen from water (e.g., steam). In a SOEC, a positive potential is applied to the oxygen electrode side of the cell and the oxygen ions are transported from the fuel electrode side to the oxygen electrode side. Since the cathode and anode are reversed between a solid oxide fuel cell (SOFC) and SOEC (i.e., SOFC cathode is SOEC anode, and SOFC anode is SOEC cathode), going forward, the SOEC anode will be referred to as the oxygen electrode, and the SOEC cathode will be referred to as the fuel electrode (i.e., a steam electrode or hydrogen product electrode).

FIG. 1A is a schematic diagram of the electrolyzer cell system 100 according to a first embodiment. The system 100 includes a hot box 110 containing one or more electrolyzer cell stacks 10, such as solid oxide electrolyzer cell stacks, and other components, such as fluid conduits, heat exchangers and heaters, as will be described in more detail below with respect to FIG. 1B. The electrolyzer cell stacks may be arranged in columns, with each column containing one or more electrolyzer cell stacks.

Liquid water may be provided to the hot box 110 from a water source 101. The liquid water may be substantially pure liquid water (e.g., filtered or distilled water). The water source 101 may comprise filters and/or distillation systems that are fluidly connected to a municipal water supply, or a water tank containing filtered or distilled water. The liquid water from the water source 101 is provided to the hot box 110 though at least one conduits 102 and 104. A water splitter 140 may optionally be coupled to conduit 104 and a heat exchanger 150 may optionally be coupled to conduits 102 and 104. In one embodiment, all or a portion of the liquid water is provided from the water source 101 through a water source conduit 102 to the heat exchanger 150, where the liquid water is preheated to between 60 and 90 degrees Celsius. The preheated water is provided from the heat exchanger 150 to the water splitter 140 through a splitter inlet conduit 104. Alternatively, a portion of the liquid water may bypass the heat exchanger 150 and is provided at room temperature from the water source 101 directly to the water splitter 140 via the splitter inlet conduit 104 or another conduit.

A first portion of the preheated liquid water is provided from the water splitter 140 to the hot box 110 to be heated into steam via a first water inlet conduit 112. A control valve 112V may be located on the first water inlet conduit 112 to control the flow of water through the first water inlet conduit 112. A second portion of the preheated liquid water is provided to the hot box 110 via a second water inlet conduit 113 to be further preheated. A third portion of the preheated liquid water is provided from the water splitter 140 to a water injector 160 via a third water inlet conduit 114.

The liquid water from the first water inlet conduit 112 is converted into steam in the hot box 110 and is then provided from the hot box 110 to a steam mixer 120 via a first steam conduit 106. The liquid water from the second water inlet conduit 113 is further heated to a temperature of between 75 and 95 degrees Celsius in the hot box 110 and is then provided from the hot box 110 into a vaporizer 170 via a vaporizer conduit 107. The water is vaporized into steam in the vaporizer 170. The steam is provided from the vaporizer 170 to the steam mixer 120 via a second steam conduit 108. Optionally, additional steam is provided from an external steam source (e.g., a building, a factory, etc.) 180 to the steam mixer 120 via an external steam conduit 109. The mixed steam is provided from the steam mixer 120 into the hot box 110 via a steam inlet conduit 116. Steam from the inlet conduit 116 is provided to the fuel electrodes in the electrolyzer stacks 10.

An air inlet stream may be provided the hot box 110 by blower 118 via an air inlet conduit 122. The hot box 110 may also generate oxygen (O₂) enriched air output via air exhaust conduit 128. Oxygen in the enriched air output can be considered a secondary product stream generated in the electrolyzer stacks 10. As described above, the oxygen enriched air is a mixture of the air inlet stream provided to the oxygen electrodes of the SOECs in the hot box 110 and oxygen ions which are transported from the fuel electrodes to the oxygen electrodes of the SOECs in the hot box 110. Further description of the processing of the steam and air in the hot box 110 is described below with respect to FIG. 1B.

According to various embodiments, the hot box 110 may output a main product (i.e., exhaust) stream of the SOECs in the electrolyzer cell stack(s) via the exhaust conduit 111. This main product stream may be composed of steam (H₂O) and hydrogen. The main product stream from the hot box 110 is provided to the product separator 130 via the exhaust conduit 111. The product separator 130 may comprise a flow splitter (e.g., a T-shaped conduit junction) and/or a three-way valve which splits the combined main product stream into two portions. Alternatively, the product separator 130 may comprise a hydrogen separator, such as an electrochemical hydrogen separator (e.g., a proton exchanger membrane separator), which separates hydrogen from the steam in the main product stream.

The product separator outputs a first portion of the main product stream into a first recycle conduit 115A, and outputs a second portion of the main product stream into a first hydrogen conduit 119A. If the product separator 130 comprises a splitter or valve, the first and second portions of the main product stream both include hydrogen and water (e.g., steam). If the product separator 130 comprises a hydrogen separator, the first portion of the main product stream comprises only steam or majority steam with some residual hydrogen, and the second portion of the main product stream comprises only hydrogen or majority hydrogen with some residual water.

The first recycle conduit 115A provides the first portion of the main product stream into a water injector 160, which may comprise any suitable water injector, such as a liquid water dripper, sprayer or nozzle. As described above, the water injector 160 may receive the liquid water from water splitter 140 via the third inlet conduit 114. Inside the water injector 160, the liquid water may be dripped or sprayed from one or more openings and/nozzles into the first portion of the main product stream flowing from the first recycle conduit 115A. The rapid evaporation of the liquid water may simultaneously cool the first portion of the main product stream (e.g., steam and optionally hydrogen being recycled into the hot box 110) and generate more steam in the water injector 160 by evaporating the liquid water. The water injector 160 outputs the cooled first portion of the main product stream into the second recycle conduit 115B. In one embodiment, the first and second recycle conduits may comprise a continuous recycle conduit (e.g., pipe or manifold) and the water injector 160 may comprise an end portion of the third water inlet conduit 114 which comprises at least one opening or nozzle that is connected to the continuous recycle conduit. The water flowrate to the water injector 160 may be varied to maintain a desired recycle blower 138 inlet temperature, e.g., 105 to 135° C., such as 120° C.

A recycle blower 138 located on the second recycle conduit 115B blows the cooled first portion of the main product stream back into the hot box 110 for use in the electrolyzer cell stack(s). The addition of the water based cooling of the recycled portion of the main product stream in the water injector 160 reduces energy use and is more efficient and cost effective than using a separate air-product heat exchanger. Thus, in one embodiment, an air-product heat exchanger which cools the recycled product stream using the air inlet stream may be omitted from the system 100 (e.g., omitted from the hot box 110). Therefore, in one embodiment, the main product stream does not exchange heat with the air inlet stream in a heat exchanger. The omission of the air-product heat exchanger (e.g., an air preheater heat exchanger, also referred to as a cathode product cooler heat exchanger) reduces the cost of the system 100 components and simplifies the structure of the hot box 110 components. Furthermore, by cooling the recycled product stream with liquid water instead of with the air inlet stream, the amount of air that is needed to cool the recycled product stream in the air-product heat exchanger is reduced. Thus, the amount of energy used by the air blower 118 may also be reduced because the volumetric flow rate of the air inlet stream may be reduced.

The second portion of the main product stream is provided from the separator 130 to the heat exchanger 150 via the first hydrogen conduit 119A. The second portion of the main product stream is cooled in heat exchanger 150 using the liquid water provided to the heat exchanger 150 from the water source 101. The heat exchanger 150 may comprise a co-flow or counter-flow heat exchanger that includes separate conduits and/or a wall to keep the water separate from the second portion of the product stream. The liquid water from the water source conduit 102 may enter the heat exchanger 150 on a cold side and exit on a hot side to the splitter inlet conduit 104 which may carry the preheated liquid water to the water splitter 140.

The cooled second portion of the main product stream is provided from the heat exchanger 150 to a hydrogen processor 190 via a second hydrogen conduit 119B. The hydrogen processor 190 may include a hydrogen pump in order to remove from about 70% to about 90% of the hydrogen from the second portion of the main product stream. Thus, the heat exchanger 150 sufficiently lowers the temperature second portion of the main product stream in order not to damage the hydrogen pump of the hydrogen processor 190. For example, the heat exchanger may lower the temperature second portion of the main product stream to below 100 degrees Celsius, such as 60 to 90 degrees Celsius. In this case, a low temperature hydrogen pump may be used to separate the hydrogen. Thus, it is not necessary to use a more expensive high temperature hydrogen pump that operates at a temperature 120 to 200 degrees Celsius. The separated hydrogen product is stored and/or provided via hydrogen processor outlet conduit 191 for one or more end uses, and the separated water may be discharged or recycled into the water source 101. Optionally, a portion of the separated hydrogen is provided back into the hot box 110 via recycled hydrogen conduit 126 for use in the electrolyzer cell stack(s) (e.g., during steady-state, start-up, shut-down and/or emergency operating modes of the stack(s)).

In one embodiment, the hydrogen processor 190 includes at least one electrochemical hydrogen pump, a liquid ring compressor, a diaphragm compressor or combination thereof. For example, the hydrogen processor may include a series of electrochemical hydrogen pumps, which may be disposed in series and/or in parallel with respect to a flow direction of the main product stream, in order to compress the main product stream. The final product from compression may still contain traces of water. As such, the hydrogen processor 190 may optionally include a dewatering device, such as a condenser, a temperature swing adsorption reactor or a pressure swing adsorption reactor, to remove this residual water, if necessary.

The pre-heating of water in the heat exchanger 150 may augment, reduce, or eliminate the pre-heating of the water in the hot box 110 prior to generating steam for the electrolyzer cell stack(s). Steam generation in a vaporizer is energy intensive, and energy may be reduced because the water is preheated in the heat exchanger 150. Furthermore, the recycled steam provided to the stack(s) from the second recycle conduit 115B may reduce the amount of steam generated by evaporation of liquid water.

FIG. 1B is a schematic diagram of the hot box 110 components of the electrolyzer cell system 100 of FIG. 1A. The hot box 110 contains one or more SOEC stacks 10 or columns, including multiple SOECs. The hot box 110 also includes steam recuperator heat exchanger 210, an air recuperator heat exchanger 220, a first water heat exchanger 230, a second water heat exchanger 240, a hydrogen mixer 250, a stack heater 260, a steam heater 270 and an air heater 280. In an alternative embodiment, the hydrogen mixer 250 may be located outside the hot box 110.

During operation, the stack(s) 10 may be provided with the air inlet stream from the air inlet conduit 122, a steam inlet stream from mixed steam inlet conduit 206, and electric power (e.g., current at an appropriate voltage-V) from an external power source. In particular, the steam may be provided to the fuel electrodes of the electrolyzer cells in the stacks 10, and the power source may apply a voltage between the fuel electrodes and the oxygen electrodes, in order to electrochemically split water (i.e., steam) molecules and generate hydrogen and oxygen. The air inlet stream is provided to the oxygen electrodes, in order to sweep the oxygen from the oxygen electrodes. As such, the stacks 10 may output the main product stream to the product outlet conduit 208 and the oxygen enriched air (i.e., oxygen exhaust) to an oxygen outlet conduit 222.

The steam inlet stream provided from the steam inlet conduit 116 may be mixed with hydrogen and/or recycled main product stream in a hydrogen mixer 250. For example, the steam inlet stream provided from the steam inlet conduit 116 may be mixed with the first portion of the main product stream provided from the second recycle conduit 115B. The first portion of the main product stream may comprise steam or a mixture of steam and hydrogen. The steam inlet stream may also be mixed with the recycled hydrogen stream from the recycled hydrogen conduit 126 in addition to or instead of being mixed with the first portion of the main product stream. The hydrogen mixer 250 may comprise a junction of the conduits 115B, 116 and 126. Alternatively, the hydrogen mixer 250 may comprise two separate junctions of conduits 115B, 116 and/or 126. The hydrogen mixer 250 outputs a steam inlet stream via the mixed steam inlet conduit 206 which is fluidly connected to the hydrogen mixer 250.

In one embodiment, the steam inlet stream may comprise a mixture of steam and hydrogen. In some embodiments, the hydrogen may be provided to the hydrogen mixer 250 during system startup and shutdown modes, and optionally during steady-state operation mode. For example, the hydrogen may be provided to the hydrogen mixer 250 from the hydrogen processor 190 via the recycled hydrogen conduit 126 during the startup and shutdown modes (or other modes where the system 100 is not generating hydrogen, such as a fault mode or standby mode). During the steady-state operating mode, the hydrogen flow from the hydrogen processor 190 may optionally be stopped (e.g., by shutting off an outlet valve 192 from the hydrogen processor 190 to the recycled hydrogen conduit 126).

The steam inlet stream output from the hydrogen mixer 250 is provided to the steam recuperator 210 via the mixed steam inlet conduit 206. The steam inlet stream is heated in the steam recuperator 210 by the main product exhaust (i.e., the hydrogen and steam product stream) provided from the stack(s) 10. The main product stream may be provided from the stack(s) 10 at a temperature above 600° C., such as 650° C. to 800° C., to the steam recuperator 210 via the product outlet conduit 208. The heated steam inlet stream is provided from the steam recuperator heat exchanger 210 into the fuel side inlet of the stack 100 via an inlet conduit 209. The mixed steam and hydrogen inlet stream in the inlet conduit 209 may have a temperature above 500° C., such as 550° C. to 750° C.

The cooled main product stream is output from the steam recuperator 210 at a temperature below 300° C., such as 200° C. to 300° C., into the exhaust conduit 111. As described above with respect to FIG. 1A, the exhaust conduit 111 provides the main product stream into the product separator 130 which may be located outside the hot box 110.

The air recuperator heat exchanger 220 may be provided with roughly ambient temperature air inlet stream from the air inlet conduit 122. The enriched air stream output from the stack(s) 10 at a temperature above 600° C., such as 650° C. to 800° C., may be provided to the air recuperator 220 via the oxygen outlet conduit 222. The air recuperator 220 may be configured to heat the air inlet stream using heat extracted from the oxygen enriched air stream. The air inlet stream may be heated in the air recuperator 220 to a temperature above 500° C., such as 550° C. to 750° C. The heated air inlet stream is provided from the air recuperator 220 to the air inlet of the stack(s) 10 via the stack air inlet conduit 212.

The enriched air stream is output from the air recuperator 220 to the first water heat exchanger 230 via the first oxygen exhaust conduit 228A at temperature above 150° C., such as 170° C. to 250° C. The first portion of the liquid water is provided from the first water inlet conduit 112 into the first water heat exchanger 230. The first portion of the liquid water is converted into steam in the first water heat exchanger 230 using the heat from the enriched air stream. The steam is output from the first water heat exchanger 230 at temperature above 100° C., such as 110° C. to 160° C., into the first steam conduit 106.

The enriched air stream is output from the first water heat exchanger to the second water heat exchanger 240 via the second oxygen exhaust conduit 228B at temperature above 80° C., such as 100° C. to 150° C. The enriched air stream is output from the second water heat exchanger 240 via the air exhaust conduit 128 at temperature of 50° C. to 120° C. The second portion of the liquid water is provided from the second water inlet conduit 113 into the second water heat exchanger 240. The second portion of the liquid water is heated in the second water heat exchanger 240 using the heat from the enriched air stream. The second portion of the liquid water is output from the second water heat exchanger 230 at temperature below 100° C., such as 60° C. to 95° C., into the vaporizer conduit 107.

The stack heater 260 may be located radially inward of the stacks 10 or columns and radially outward of the steam recuperator 210 in the hot box 110. The stack heater 260 may heat the stacks 10 or columns. The steam heater 270 may be located radially inward of the steam recuperator 210 in the center of the hot box 110. The steam heater 270 may heat the steam inlet stream flowing through the steam recuperator 210 and/or the inlet conduit 209 to a temperature above 600° C., such as 650° C. to 750° C. The air heater 280 may be located radially outward of the air recuperator 220 in the hot box 110. The air heater 280 may further heat the air inlet stream flowing through the air recuperator 220 and/or the stack air inlet conduit 212 to a temperature above 750° C., such as 800° C. to 950° C. Alternatively, the system may be operated in a thermally neutral state with one or more of the heaters turned off.

According to various embodiments, the system 100 may include a system controller 290, such as a central processing unit, which is configured to control the operation of the system 100. For example, the controller 290 may be wired or wirelessly connected to various elements of the system 100 to control the same. For example, the system controller 290 may control the temperature of the heaters 260, 270, 280, the speed of the blowers 118, 138 and/or the operation of the various valves (e.g., 112V, etc.).

FIG. 2 is a schematic diagram of the electrolyzer cell system 200 according to a second embodiment. The system 200 of FIG. 2 shares many components and aspects with the system 100 of FIG. 1A and, therefore, only the differences are described here. According to second embodiment, the heat exchanger 150 and the water source conduit 102 may be omitted. Therefore, the first and second hydrogen conduits 119A and 119B are combined into a single hydrogen conduit 119 because the heat exchanger 150 is omitted, and the water may be provided from the water source 101 directly to the water splitter 140. Furthermore, the water injector 160 is moved inside the hot box 110. Therefore, the first and second recycle conduits 115A and 115B are combined into a single recycle conduit.

In the second embodiment, the water injector 160 is located on the exhaust conduit 111 in the hot box 110 instead of on the recycle conduit 115 outside the hot box 110. Therefore, the cool water from the water injector 160 cools the main product (i.e., exhaust) stream of the electrolyzer cell stack(s) 10. In the second embodiment, the cool water from the water injector 160 may lower the temperature of the main product stream to below 100 degrees Celsius, such as 60 to 90 degrees Celsius. In this case, a low temperature hydrogen pump may be used to separate the hydrogen. Thus, it is not necessary to use a more expensive high temperature hydrogen pump that operates at a temperature 120 to 200 degrees Celsius. Therefore, in the second embodiment, the water injector 160 cools the main product exhaust instead of the heat exchanger 150 of the first embodiment.

FIG. 3 is a schematic diagram of the electrolyzer cell system 300 according to a third embodiment. The system 300 of FIG. 3 shares many components and aspects with the system 100 of FIG. 1A and, therefore, only the differences are described here. According to the third embodiment, the product separator 130 and the water injector 160 are moved inside the hot box 110. In this embodiment, the product separator 130 comprises a product splitter. The exhaust conduit 111 which fluidly connects the electrolyzer cell stack(s) 10 to the product separator 130 and the first recycle conduit 115A which fluidly connects the product separator 130 to the water injector 160 are also located entirely in the hot box 110.

FIG. 4 is a schematic diagram of the electrolyzer cell system 400 according to a fourth embodiment. The system 400 of FIG. 4 shares many components and aspects with the system 100 of FIG. 1A and, therefore, only the differences are described here. According to the fourth embodiment, the system 400 components other than the external steam source 180 and the water source 101 are located inside a cabinet 410. The cabinet 410 may comprise any suitable system housing, such as a metal box having at least one door. The cabinet 410 may optionally include an additional cabinet air blower 418 which provides air into the cabinet 410 via an air inlet 422, such as an opening in a door of the cabinet 410 or one or more vents disposed on the cabinet housing. Alternatively, the additional air cabinet blower 418 may be omitted, and the air blower 118 may be used to provide air into the cabinet 410 and into the air inlet conduit 122. The cabinet 410 may also include an air heat exchanger 420 located on the exhaust conduit 111 or on the first recycle conduit 115A (as shown in by the dashed lines).

The air heat exchanger 420 uses the cabinet air (i.e., the air inside the cabinet 410) to cool the main product stream in the exhaust conduit 111 and/or to cool the first portion of the main product stream in the first recycle conduit 115A. The air heat exchanger 420 may comprise fins or other protrusions located on an external surface of the exhaust conduit 111 and/or the first recycle conduit 115A. The cabinet air cooling reduces the temperature of the first portion of the main product stream provided to the recycle blower 138, which reduces or prevents damage to the blower 138.

According to various embodiments, an electrolyzer cell system (100, 200, 300 and/or 400) includes a stack of electrolyzer cells 10. In one embodiment, the stack 10 comprises a stack of solid oxide electrolyzer cells. The stack 10 is located in a hot box 110 and configured to generate a main product stream comprising hydrogen and steam, and an oxygen exhaust stream (i.e., the oxygen enriched air stream or secondary product stream). The system also includes a steam source (170, 180 and/or 230) fluidly connected to the stack 10 and configured to provide the steam inlet stream to the stack 10. As used herein, fluidly connected means that two components are either directly connected to each other or indirectly connected to each other through at least one other component, such that a fluid can flow between the first and the second components. The system also includes at least one product conduit (111, 115, 115A, 115B, 119, 119A and/or 119B) fluidly connected to the stack 10 and configured to receive the main product stream, and a water injector 160 configured to provide liquid water into the main product stream in the at least one product conduit.

In one embodiment, the system further comprises a liquid water source 101 fluidly connected to the water injector 160 (e.g., through one or more conduits 102, 104 and/or 114 and/or water splitter 140), and an air blower 118 fluidly connected to the stack and configured to provide an air inlet stream into the stack 10. The system further comprises a product separator 130 fluidly connected to the at least one product conduit and configured to separate the main product stream into a first portion and a second portion, and a recycle blower 138 fluidly connected to the at least one product conduit (115B or 115) and configured to recycle the first portion of the main product stream into the stack.

In some embodiments, the at least one product conduit comprises an exhaust conduit 111 fluidly connecting the stack 10 to an inlet of the product separator 130, at least one recycle conduit (115A, 115B, 115) fluidly connecting a first outlet of the product separator 130 to the stack 10 through the recycle blower 138; and at least one hydrogen conduit (119A, 119B or 119) fluidly connecting a second outlet of the product separator 130 to a hydrogen outlet (e.g., to a hydrogen processor 190 or to a hydrogen storage vessel) of the electrolyzer cell system.

In the embodiments of FIGS. 1A, 3 and 4, the water injector 160 is located on the at least one recycle conduit (115A) upstream of the recycle blower 138. In the embodiment of FIG. 2, the water injector 160 is located on the exhaust conduit 111 inside the hot box 110.

In the embodiments of FIGS. 1A, 3 and 4, a heat exchanger 150 is located on the at least one hydrogen conduit (119A, 119B), a water source conduit 102 fluidly connects a water source 101 to an inlet of the heat exchanger 150; and at least one water inlet conduit (104, 114) fluidly connects an outlet of the heat exchanger 150 to the water injector 160, and is configured to provide liquid water preheated by the second portion of the main product stream to the water injector 160.

In one embodiment shown in FIG. 1B, the system (100, 200, 300, 400) also includes at least one water heat exchanger (230 and/or 240) configured to convert liquid water to steam using heat from the oxygen exhaust stream, at least one water inlet conduit (112 and/or 113) fluidly connected to an inlet of the at least one water heat exchanger; at least one oxygen exhaust conduit fluidly (228A and/or 228B) connecting an outlet of the stack to the at least one water heat exchanger (230 and/or 240) and configured to provide the oxygen exhaust stream to the at least one water heat exchanger, and at least one steam conduit (106, 107, 108, 116, 206) fluidly connecting an outlet of the at least one water heat exchanger (230 and/or 240) to the stack 10.

In one embodiment, the at least one water heat exchanger comprises first and second water heat exchangers 230 and 240 located in the hot box 110. The at least one water inlet conduit comprises a first water inlet conduit 112 fluidly connected to at inlet of the first water heat exchanger 230, and a second water inlet conduit 113 fluidly connected to an inlet of the second water heat exchanger 240. The at least one steam conduit comprises a first steam conduit 106 fluidly connecting an outlet of the first water heat exchanger 230 to a first inlet of a steam mixer 120, a vaporizer conduit 107 fluidly connecting an outlet of the second heat exchanger 240 to an inlet of a water vaporizer 170, a second steam conduit 108 fluidly connecting an outlet of the water vaporizer 170 to a second inlet of the steam mixer 120, and a steam inlet conduit 116 fluidly connecting an outlet of the steam mixer 120 to a steam inlet of the stack 10 (e.g., indirectly connecting the outlet of the steam mixer to the steam inlet of the stack 10 via the hydrogen mixer 250, the steam recuperator 210 and conduits 206 and 209). The steam source (170, 180 and/or 230) comprises at least one of the first water heat exchanger 130, the water vaporizer 170 and/or the external steam source 180.

In one embodiment, the water splitter 140 fluidly connects the water source 101 to the first water inlet conduit 112 and the second water inlet conduit 113. A third water inlet conduit 114 fluidly connects an outlet of the water splitter 140 to an inlet of the water injector 160.

The electrolyzer cell systems of various embodiments of the present disclosure are designed to reduce greenhouse gas emissions and have a positive impact on the climate.

The preceding description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.