Fluid separation systems for an electrochemical system

Abstract

A system for separating a fluid in the operation of an electrochemical system includes: a cathode separator configured to separate a fluid into a first stream having hydrogen gas and a second stream having water and dissolved hydrogen; and a makeup water tank. The makeup water tank is configured to: receive the second stream from the cathode separator; operate at a pressure that is greater than atmospheric pressure and less than an operating pressure of the cathode separator; and separate at least a portion of the dissolved hydrogen from the water via a reduction in pressure from the cathode separator to the makeup water tank to provide a purified water stream and hydrogen gas. The hydrogen gas from the makeup water tank is configured to be transferred out of the makeup water tank and the purified water stream is configured to be transferred out the makeup water tank.

Description

FLUID SEPARATION SYSTEMS FOR AN ELECTROCHEMICAL SYSTEM

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 623,979, filed January 23, 2024, which is hereby incorporated by reference in its entirety.FIELD

[0002] The following disclosure relates to an electrochemical system and components thereof. More specifically, the following disclosure relates to a system and method for separating fluid from a cathode side of an electrolyzer into hydrogen gas and water during operation of the electrochemical system to provide a purified water stream capable of being recycled or reused within the electrochemical system.BACKGROUND

[0003] An electrochemical cell or system uses electrical energy to drive a chemical reaction. For example, within a water splitting electrolysis reaction within the electrolysis cell, water is split to form hydrogen and oxygen. The products may be used as energy sources for later use. In recent years, improvements in operational efficiency have made electrolyzer systems competitive market solutions for energy storage, generation, and / or transport. For example, the cost of generation may be below $6 per kilogram of hydrogen in certain cases. Increases in efficiency and / or improvements in operation will continue to drive installation of electrolyzer systems.

[0004] Electrochemical systems may include subsystems associated with both the anode and cathode sides of the system, working in tandem to split water into hydrogen and oxygen. During operation, water continuously moves across the membrane from the anode to the cathode through electro-osmosis. To prevent water accumulation in the cathode subsystem, the electro-osmotic (or 'protonic') water is redirected back to the anode side. However, as the cathode side may operate at higher than atmospheric pressure, the water may retain dissolved hydrogen. The amount of dissolved hydrogen needs to be reduced to a safe level before reintroducing the water to the anode side to prevent the formation of a combustible mixture.

[0005] Current systems and methods to remove dissolved hydrogen unfortunately compromise, reduce, or remove the efficiency of separating the fluid leaving the cathode side of an electrolyzer. As such, there remains a need to provide an improved fluid separation system for an electrochemical system.SUMMARY

[0006] In one embodiment, a fluid separation system for an electrolyzer includes a cathode separator configured to receive a fluid from an outlet of a cathode side of the electrolyzer. The cathode separator is configured to separate the fluid into a first stream having hydrogen gas and a second stream having water and dissolved hydrogen. The fluid separation system further includes a makeup water tank configured to receive the second stream from the cathode separator. The makeup water tank is configured to operate at a pressure that is greater than atmospheric pressure and less than an operating pressure of the cathode separator. The makeup water tank is also configured to separate at least a portion of the dissolved hydrogen from the water via a reduction in pressure from the cathode separator to the makeup water tank to provide a purified water stream and hydrogen gas. The hydrogen gas from the makeup water tank is configured to be transferred out of the makeup water tank and the purified water stream is configured to be transferred out of an outlet of the makeup water tank to the electrolyzer.

[0007] In another embodiment, a method for separating a fluid produced within an electrochemical system, the method includes: receiving, by a cathode separator of the electrochemical system, a fluid from an outlet of a cathode side of an electrochemical stack of the electrochemical system; and separating, by the cathode separator, the fluid into a first stream including hydrogen gas and a second stream including water and dissolved hydrogen. The method further includes: receiving, by a makeup water tank of the electrochemical system, the second stream from the cathode separator; and separating, by the makeup water tank, at least a portion of the dissolved hydrogen from the water via a reduction in pressure from the cathode separator and the makeup water tank to provide a purified water stream and hydrogen gas. The method also includes transferring the purified water stream out of an outlet of the makeup water tank to the electrochemical stack. Themakeup water tank is configured to operate at a pressure that is greater than atmospheric pressure and less than an operating pressure of the cathode separator.

[0008] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Exemplary embodiments are described herein with reference to the following drawings.

[0010] Figure 1A depicts an example of an electrochemical or electrolytic cell.

[0011] Figure IB depicts an example of a system including an electrochemical stack having a plurality of electrochemical cells of Figure 1A.

[0012] Figure 2 depicts an embodiment of a fluid separation system.

[0013] Figure 3 depicts a flowchart describing a method for separation fluid from a cathode side of an electrolyzer into Hydrogen gas and water.

[0014] Figure 4 depicts a flowchart describing a method for pressurizing a fluid separation system by a gas supply system .

[0015] Figure 5 depicts a flowchart describing a method for adding an ultra-purified water stream to a fluid separation system by a water purification system.

[0016] Figure 6 illustrates an exemplary system for controlling an operation of a fluid separation system.

[0017] Figure 7 depicts an example of a computing device having a controller.

[0018] While the disclosed compositions and methods are representative of embodiments in various forms, specific embodiments are illustrated in the drawings (and are hereafter described), with the understanding that the disclosure is intended to be illustrative and is not intended to limit the claim scope to the specific embodiments described and illustrated herein.DETAILED DESCRIPTION

[0019] The following discussion relates to systems and methods for (e.g., actively and continuously) separating fluid leaving the cathode side of a proton exchange membrane(PEM) electrolyzer in the operation of electrolysis systems. The disclosure advantageously describes a fluid separation system that separates the fluid leaving the cathode side of an PEM electrolyzer into hydrogen gas and water at an inexpensive cost. Additionally, the disclosure advantageously provides a less complex system with fewer parts, a system that is passively operated, limits the possibility of atmospheric carbon dioxide from entering the system, efficiently collects any remaining hydrogen, and reuses the separated water by pumping the water back into the anode side of the electrolyzer.

[0020] Furthermore, the system maintains positive pressure, thus advantageously providing a steady flow of pure hydrogen to prevent atmospheric air from encountering the water inside the makeup water tank. Examples of such systems and methods are described in greater detail below.

[0021] Figure 1A depicts an example of an electrochemical cell for the production of hydrogen gas and oxygen gas through the splitting of water. The electrochemical cell includes a cathode, an anode, and a membrane positioned between the cathode and anode. Within the water-splitting electrolysis reaction, one interface runs an oxygen evolution reaction (OER) while the other interface runs a hydrogen evolution reaction (HER). For example, the anode reaction is H2O->2H++ / 2O2+2e and the cathode reaction is 2H++2e->H2. The water electrolysis reaction has recently assumed great importance and renewed attention as a potential foundation for a decarbonized "hydrogen economy."

[0022] Figu re IB depicts an example of an electrochemical system including an electrolyzer or electrochemical stack having a plurality of electrochemical cells of Figure 1A. In certain examples, the electrolyzer or electrochemical stack may contain 50-1000 cells, 50- 100 cells, 500-700 cells, or more than 1000 cells. Any number of cells may make up a stack. The electrochemical cells within the electrochemical stack may be configured to operate with 200 mV or less of pure resistive loss when operating at a high current density (e.g., at least 3 Amps / cm2, at least 4 Amps / cm2, at least 5 Amps / cm2, at least 6 Amps / cm2, at least 7 Amps / cm2, at least 8 Amps / cm2, at least 9 Amps / cm2, at least 10 Amps / cm2, at least 11Amps / cm2, at least 12 Amps / cm2, at least 13 Amps / cm2, at least 14 Amps / cm2, at least 15Amps / cm2, at least 16 Amps / cm2, at least 17 Amps / cm2, at least 18 Amps / cm2, at least 19Amps / cm2, at least 20 Amps / cm2, at least 25 Amps / cm2, at least 30 Amps / cm2, in a range of1-30 Amps / cm2, in a range of 3-20 Amps / cm2, in a range of 3-15 Amps / cm2, in a range of 3- 10 Amps / cm2, or in a range of 10-20 Amps / cm2).

[0023] As illustrated in the system of Figure IB, water (H2O) may be supplied to the anodic inlet of an electrolyzer or electrochemical stack 12. In certain embodiments, only the anodic inlet of the electrochemical stack 12 may receive water. In these embodiments, the cathode side of the electrochemical stack 12 may not receive water (e.g., a dry cathode side may be used). In another embodiment, a cathode inlet may also receive water, wherein the water may be supplied to the cathode inlet to cool the electrochemical stack 12 during electrolysis.

[0024] The water supplied to the anodic inlet flows to an anodic inlet manifold that distributes the water to the anode side of the plurality of cells contained with the electrochemical stack 12. In embodiments where water is supplied to the cathode inlet, water supplied to the cathode inlet flows to a cathodic inlet manifold that distributes the water to the cathode side of the plurality of cells in the electrochemical stack 12. In certain examples, the amount of water (e.g., deionized (DI) water) transferred to or circulated through each cell of the electrochemical stack 12 may be in a range of 0.25-1 mL / Amp / cell / min, in a range of 0.25-5 mL / Amp / cell / min, or in a range of 0.5-1 mL / Amp / cell / min.

[0025] During electrolysis, oxygen (O2) is produced at the anode side of the electrolytic cells and hydrogen (H2) is produced at the cathode side of the electrolytic cells. Specifically, a water splitting electrolysis reaction is configured to take place within each individual cell in the cell stack 12. Each cell includes one interface (the anode side of the cell) configured to run an oxygen evolution reaction (OER) and another interface (the cathode side of the cell) configured to run a hydrogen evolution reaction (HER), such as depicted in Figure 1A.

[0026] To prevent water accumulation in the cathode subsystem, the electro-osmotic (or 'protonic') water is redirected back to the anode side. However, as the cathode side may operate at pressure greater than atmospheric pressure (e.g., at least 5 atm, at least 10 atm, at least 20 atm, at least 30 atm, at least 40 atm, in a range of 2-40 atm, in a range of 10-40 atm, in a range of 20-40 atm, or in a range of 20-30 atm), the water may retain an undesirable amount of dissolved hydrogen. This dissolved hydrogen needs to be reduced toa safe level before reintroducing the water to the anode side to prevent the formation of a combustible mixture.

[0027] One solution involves utilizing a low-pressure or atmospheric vessel, enabling the hydrogen to separate from the solution and escape to the atmosphere through a vent stack. The water then enters a large atmospheric buffer tank, referred to as the "makeup water tank," where it combines with the output from a water purification subsystem before being pumped back into the anode subsystem.

[0028] In certain examples, a vessel or "effervescent hydrogen separator" precedes the makeup water tank (i.e., is positioned between the cathode separator and the makeup water tank), wherein hydrogen is extracted from the water within the vessel or effervescent hydrogen separator via a reduction or drop in pressure from the cathode separator, and the water is then transferred to the makeup water tank. However, there is a potential risk of the ultra-pure water (UPW) coming into contact with atmospheric carbon dioxide in the makeup tank. UPW is specifically purified for its application in the electrolysis process. Any contamination or alteration in its chemical composition may directly impact the efficiency and effectiveness of the electrolysis reaction.

[0029] Therefore, the proposed systems disclosed herein aim to advantageously preserve the purity of the water, maintain the integrity of the electrolysis process, and prevent any potential damage or chemical reactions that may hinder the overall performance of the electrolyzer system.Fluid Separation Systems

[0030] Figure 2 depicts an embodiment of an electrochemical system having a fluid separation system 200. In this depicted example, a fluid is received from an outlet of a cathode side of an electrochemical stack 100. As noted above, this may be a fluid or stream provided from the cathodic outlet 102 of the electrochemical stack (e.g., electrolyzer) 100. This fluid steam may include water and hydrogen gas produced from the water splitting reaction within the electrochemical stack 100. Due to the operating pressure on the cathode side of the electrochemical stack, a portion of the hydrogen gas may be dissolved within the water. As such, a fluid separation system is needed to separate the hydrogen gas from the water to provide a valuable hydrogen gas product stream and recycle a purified waterstream back to the electrochemical stack for further use (i.e., for water splitting or for cooling).

[0031] The fluid separation system 200 may include a cathode separator 210, a makeup water tank 220, an anode separator 230, and a water purification system 240. The system 200 advantageously separates the fluid into gas and liquid while allowing a majority of the (e.g., hydrogen) gas to flow out of the system 200 and be collected for further use. The liquid (e.g., water) may advantageously be purified and recycled for further use within the electrochemical system. In certain examples, a purified water stream is transferred out of the system 200 through the anode separator 230 into an anodic inlet 104 of the anode side of an electrochemical stack 100.

[0032] The cathode separator 210 is configured to receive the fluid from an outlet of the electrochemical stack 100. In this embodiment, the cathode separator 210 is configured to receive the fluid from the cathodic outlet 102 of the electrochemical stack 100. The cathode separator 210 may be configured to operate at a pressure greater than atmospheric pressure. In certain examples, the operating pressure of the cathode separator 210 is similar to the operating pressure on the cathode side of the electrochemical stack. This operating pressure may be at least 1.1 atm, at least 2 atm, at least 3 atm, at least 5 atm, or at least 10 atm, at least 20 atm, at least 30 atm, or at least 40 atm. In certain examples, the operating pressure of the cathode separator may be in a range of 1.1-40 atm, 1.1-30 atm, 1.1-20 atm, 1.1-10 atm, 2-40 atm, 2-30 atm, 2-20 atm, 2-10 atm, 3-40 atm, 3-30 atm, 3-20 atm, 3-10 atm, 5-40 atm, 5-30 atm, 5-20 atm, 5-10 atm, 10-40 atm, 10-30 atm, or 10-20 atm.

[0033] The cathode separator 210 is configured to separate the fluid into a first stream that is at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99% of hydrogen gas and a second stream including water and the remaining hydrogen dissolved in the water.

[0034] An important or advantageous purpose of the initial separation is to capture the hydrogen gas. As a result, the first stream (i.e., including a majority of the hydrogen gas produced within the electrochemical stack) may be configured to flow out of a first outlet 207 of the cathode separator 210 to be collected. A control valve 213 (e.g., vent valve and / or pressure regulator) may be positioned off the cathode separator to control a flow ofthe hydrogen gas out of the first outlet 207 while maintaining the operating pressure within the cathode separator 210. A pressure sensor (not depicted) may be positioned within the cathode separator 210 or within the line leading to the control valve 213 to monitor the pressure within the cathode separator 210. The pressure sensor may be configured to transmit the pressure reading to a controller so that the pressure within the cathode separator 210 may be monitored and controlled. For example, a controller in communication with the pressure sensor may be configured to send a signal to the control valve 213 to open the valve (partially or fully) when the pressure reading exceeds a predefined threshold level. Additionally, the controller may be configured to send a signal to the control valve 213 to close the valve (partially or fully) when the pressure level drops below a predefined threshold level.

[0035] The second stream having the water and dissolved hydrogen may be configured to flow out of a second outlet 209 of the cathode separator 210 to be received by the makeup water tank 220 for further processing and separation of water and hydrogen. In this configuration, there may be no intermediate vessel between the cathode separator 210 and the makeup water tank 220. In other words, for example, there is no vessel or effervescent hydrogen separator positioned between the cathode separator and the makeup water tank. This is advantageous in reducing the number of vessels and processing equipment, the system / operating costs, the complexity of the piping system, while still effectively being able to separate hydrogen from water to provide a purified water stream for further processing within the electrochemical system.

[0036] In certain examples, the system 200 may include one or more control valves positioned between the cathode separator 210 and the makeup water tank 220. In certain examples, the one or more control valves includes a control valve 211 configured to control the level of water within the cathode separator 210 and control the flow of the second stream flowing into an inlet 214 of the makeup water tank 220.

[0037] Furthermore, as shown in Figure 2, a first level sensor223 may be positioned within the cathode separator 210 to monitor the level of the water within the cathode separator 210. The first level sensor 223 may be configured to transmit the level reading to a controller so that the water level may be monitored and controlled. For example, acontroller in communication with the first level sensor 223 may be configured to send a signal to the control valve 211 downstream of the cathode separator to open the valve (partially or fully) when the water level reading exceeds a predefined threshold level (e.g., greater than 60% of the depth of the cathode separator 210). Additionally, the controller may be configured to send a signal to the control valve 221 to close the valve (partially or fully) when the water level drops below a predefined threshold level (e.g., less than 30% of the depth of the cathode separator 210).

[0038] As depicted in Figure 2, the second stream exiting through the second outlet 209 of the cathode separator 210 is received by the control valve 211. In one example, the cathode separator 210 may be operating at an operating pressure in a range of 10-40 atm and the pressure of the second stream flowing into the makeup water tank may be a pressure below the operating pressure of the cathode separator.

[0039] For example, the makeup water tank may be configured to operate at a pressure that is greater than atmospheric pressure and less than the operating pressure of the cathode separator. The pressure may be at least 1.01 atm, at least 1.05 atm, at least 1.1 atm, at least 1.5 atm, at least 2 atm, in a range of 1.01-5 atm, in a range of 1.01-2 atm, or in a range of 1.01-1.5 atm. Alternatively, the operating pressure to the makeup water tank may be defined as a gauge pressure that is at least 0.01 barG (or atmG), at least 0.1 barG (or atmG), at least 0.5 barG (or atmG), at least 1 barG (or atmG), in a range of 0.01-5 barG (or atmG), in a range of 0.01-2 bar G (or atmG), or in a range of 0.01-1 barG (or atmG).

[0040] The control valve 211 may be configured to control a flow rate of the second stream entering into the makeup water tank 220. The flow rate may be any configurable flow rate taking into consideration the operating parameters of the electrochemical system. In certain examples, the flow rate may be at least 0.1 liters / minute (L / min), at least 1 L / min, at least 10 L / min, at least 100 L / min, at least 200 L / min, at least 1000 L / min, at least 2000 L / min, in a range of 0.1-2000 liters per minute (L / min), 10-2000 L / min, 100-2000 L / min, 0.1- 200 L / min, 1-200 L / min, 10-200 L / min, 0.1-1000 L / min, 1-1000 L / min, or 10-1000 L / min.

[0041] Additionally, in another embodiment, the first level sensor 223, the control valve 211, the control valve 213, and / or any additional sensors or valves may be controlled by at least one controller 270, further described below.

[0042] As mentioned above, the system 200 includes a makeup water tank 220 configured to receive the second stream from the cathode separator 210 through a first inlet 214. The makeup water tank may be configured to store any configurable amount of fluid based on the operating conditions within the electrochemical system. As shown in Figure 2, the makeup water tank 220 has a first inlet 214, a second inlet 216, a third inlet 221, a first outlet 217, and a second outlet 218.

[0043] The makeup water tank 220 is configured to receive the second stream of fluid from the cathode separator 210. More particularly, the makeup water tank 220 is configured to receive the second stream of fluid from an outlet of the control valve 211 through the first inlet 214. The makeup water tank 220 is configured to advantageously separate at least a portion of the dissolved hydrogen from the water in the second stream from the cathode separator 210. This may be accomplished via a reduction or drop in pressure from the cathode separator 210 to the makeup water tank 220 to assist in releasing the dissolved hydrogen within the water, therein providing a purified water stream and hydrogen gas. Additionally, or alternatively, the removal of dissolved hydrogen within the water may be accomplished via mechanical agitation within the line leading to the makeup water tank or via an agitation device positioned within the makeup water tank itself. The agitation device in the line or in the makeup water tank may be any known agitator such as an electric motor, rotary shaft, propeller, impeller, or vane configured to rotate inside the line or tank.

[0044] In either scenario, removal of the dissolved hydrogen from the water is advantageous, as noted above, in creating a safe water source to be provided or returned to the electrochemical stack for further processing. In other words, the removal of dissolved hydrogen from the water allows the introduction of the purified water stream into an oxygen rich environment on the anode side of the electrochemical stack without any safety concerns.

[0045] In certain examples, the purified water stream has a water resistivity of at least 1 megaohm*cm (M0hm*cm), at least 2 M0hm*cm, at least 5 M0hm*cm, at least 10 M0hm*cm, in a range of 1-18.2 M0hm*cm, in a range of 2-18.2 M0hm*cm, in a range of 5- 18.2 M0hm*cm, or in a range of 10-18.2 M0hm*cm.

[0046] In certain examples, the makeup water tank 220 is configured to operate at a pressure that is greater than atmospheric pressure and less than an operating pressure of the cathode separator 210. As a result of operating at a pressure greater than atmospheric pressure, the makeup water tank 220 may prevent one or more contaminants from entering into the makeup water tank 220. In other words, the hydrogen gas within the makeup water tank, having a pressure greater than atmospheric pressure, is configured to provide a protective blanket for the water. This advantageously prevents contaminants (e.g., carbon dioxide within atmospheric air), from entering the makeup water tank and affecting the purity of the water source required for the electrochemical stack.

[0047] In certain examples, the makeup water tank 220 is configured to transfer the hydrogen gas out of the tank via the first outlet 217. The first outlet 217 may include a control valve 215 positioned downstream of the makeup water tank 220. The first outlet 217 may further include a vent or transfer port 205 configured to vent the hydrogen gas to atmosphere or transfer the hydrogen gas to another vessel for further processing or storage via control of the control valve 215. For instance, the transfer port may transfer the hydrogen gas via an additional piping line (not depicted) to transfer the hydrogen gas to the hydrogen collection vessel along with the hydrogen gas collected from the cathode separator 210. In this particular depicted example, the control valve 215 may be configured to control a flow rate of the hydrogen gas transferring out of the makeup water tank 220 through the vent / transfer port 205. In this configuration, the control valve 215 is positioned between the makeup water tank 220 and the vent / transfer port 205. The control valve 215 may advantageously help control the pressure level inside of the makeup water tank 220 and may control the amount of hydrogen flowing through the vent / transfer port 205.

[0048] For example, a pressure sensor 214 may be positioned within the makeup water tank 220 or within the line leading to the control valve 215 to monitor the pressure within the makeup water tank 220. The pressure sensor may be configured to transmit the pressure reading to a controller so that the pressure within the makeup water tank 220 may be monitored and controlled. For example, a controller in communication with the pressure sensor may be configured to send a signal to the control valve 215 to open the valve (partially or fully) when the pressure reading exceeds a predefined threshold level.Additionally, the controller may be configured to send a signal to the control valve 215 to close the valve (partially or fully) when the pressure level drops below a predefined threshold level. Additionally, as described in greater detail below, a drop in pressure below a predefined threshold level may trigger a gas supply system 300 to provide additional inert gas to the makeup water tank 220 to maintain a pressure greater than atmospheric pressure.

[0049] As shown in Figure 2, the makeup water tank 220 is further configured to transfer the purified water out of the tank via the second outlet 218. In certain examples, the purified water stream may be transferred to the anode side (e.g., an anode separator 230) of the electrochemical system to be combined with recycled water retrieved from the anode outlet of the electrochemical stack. Alternatively, while not depicted, the purified water stream may be provided or returned to the electrochemical stack on the cathode side of the stack as a cooling water source for the cathode side of the stack.

[0050] In the depicted example in Figure 2, the purified water stream is transferred out of the tank via the second outlet 218 toward the anode separator 230. A third control valve 228 may be positioned in the transfer line between the makeup water tank 220 and the anode separator 230 to control the level of water within the makeup water tank 220 and / or flow rate to the anode separator 230.

[0051] In certain examples, a second level sensor or indicator 225 may be positioned within the makeup water tank 220 to monitor the level of the water within the makeup water tank 220. The second level sensor 225 may be configured to transmit a level reading to a controller so that the water level may be monitored and controlled. For example, a controller in communication with the second level sensor 225 may be configured to send a signal to the control valve 228 downstream of the makeup water tank 220 to open the valve (partially or fully) when the water level reading exceeds a predefined threshold level (e.g., greater than 60% of the depth of the makeup water tank 220). Additionally, the controller may be configured to send a signal to the control valve 228 to close the valve (partially or fully) when the water level drops below a predefined threshold level (e.g., less than 30% of the depth of the makeup water tank 220).

[0052] Referring to Figure 2, the anode separator 230 is configured to receive the purified water stream from the second outlet 218 of the makeup water tank 220 and combine this purified water stream from the cathode side of the stack with an additional water source from the anode side of the stack. Additionally, or alternatively, a pump 219 may be provided to assist in the transfer of the purified water stream to the anode separator 230. The pump 219 is configured to assist in the transfer of the purified water stream out of the second outlet 218 of the makeup water tank 220 to the inlet of the anode separator 230.

[0053] In certain examples, a return line 243 may be positioned downstream of valve 228 or pump 219 to cycle or return the purified water stream back toward the makeup water tank 220. As depicted in Figure 2, a supplemental water polishing system 244 may be provided to assist in treating or polishing the purified water source further prior to introduction of the water into the electrolyzer. A control valve 245 may be positioned within the return line 243 to control the flow rate of water to the water polishing system 244.

[0054] The at least one controller 270 of the system 200 may be configured to send a signal to the control valve 245 to control the flow rate of the purified water stream from the makeup water tank toward the water polishing system 244.

[0055] The water polishing system 244 may advantageously further treat and remove water impurities shortly before being transferred to the electrochemical stack for the water splitting reaction. This subsequent treatment / polishing of at least a portion of the makeup water directly proceeding the electrochemical stack may advantageously provide minimal chances for collecting impurities within the ultrapure water source, and therein providing optimal reaction conditions within the stack.

[0056] In certain examples, the water polishing system may include one or more polishing beds, each having a polishing composition configured to treat and remove impurities from the water source. In certain examples, the polishing composition may be a resin composition, e.g., an ion exchange resin, configured to remove impurities such as dissolved ions picked up by the waterfrom the piping or cooling surfaces within the plant. The operating conditions (e.g., operating temperature, pressure, flow rate) within the polishing bed or beds may be any known operating condition known in the art.

[0057] In certain examples, the polishing system may be configured to purify the water to have a water resistivity of at least 1 megaohm*cm (M0hm*cm) at least 2 M0hm*cm, at least 5 M0hm*cm, at least 10 M0hm*cm, at least 12 M0hm*cm, in a range of 1-18.2 M0hm*cm, in a range of 1-10 M0hm*cm, in a range of 2-18.2 M0hm*cm, in a range of 2- 10 M0hm*cm, in a range of 5-18.2 M0hm*cm, in a range of 5-10 M0hm*cm, in a range of 10-18.2 M0hm*cm, or in a range of 12-18.2 M0hm*cm.

[0058] The anode separator 230 may have an operating pressure of at least 0.01 barG (or atmG), at least 0.1 barG (or atmG), at least 0.5 barG (or atmG), at least 1 barG (or atmG), at least 5 barG (or atmG), at least 10 barG (or atmG), in a range of 0.01-10 barG (or atmG), in a range of 0.01-5 bar G (or atmG), or in a range of 0.01-1 barG (or atmG). Additionally, the pump 219 and the second pressure indicator 225 may be controlled by a controller 270, further described below.

[0059] While not depicted in Figure 2, the oxygen gas and unreacted water produced from the anode side of the stack may be separated as well, wherein the unreacted water is returned to the anode separator 230. This combined water source may then be transferred back to the anode side of the electrolyzer stack 100.

[0060] As mentioned above, the system 200 may also include a water purification system 240. The water purification system 240 is configured to be in fluid connection with the makeup water tank 220 and an (e.g., external) water source 250. The water purification system 240 is configured to receive a water stream from the external water source 250 and purify the water stream received from the external water source 250, therein providing an additional purified water stream for the system. The additional purified water stream from the water purification system 240 may have a water resistivity of at least 1 megaohm*cm (M0hm*cm), at least 2 M0hm*cm, at least 5 M0hm*cm, at least 10 M0hm*cm, in a range of 1-18.2 M0hm*cm, in a range of 2-18.2 M0hm*cm, in a range of 5-18.2 M0hm*cm, or in a range of 10-18.2 M0hm*cm.

[0061] The water purification system 240 may be configured to purify water using any known purification process to purify the water stream to have a water resistivity of at least 1 megaohm*cm (M0hm*cm) at least 2 M0hm*cm, at least 5 M0hm*cm, at least 10 M0hm*cm, in a range of 1-18.2 M0hm*cm, in a range of 2-18.2 M0hm*cm, in a range of 5-18.2 MOhm*cm, or in a range of 10-18.2 M0hm*cm. This may include one or more of the following examples. For instance, the external water may be treated via filtration to remove large particles, ion exchange or deionization through mixed bed resin columns, activated carbon filtration, or the like.

[0062] The water purification system 240 is configured to transfer the additional purified water stream to the makeup water tank 220 to combine with the water in the makeup water tank and contribute to the purified water stream being transferred out of the makeup water tank 220 to the anode separator 230. A second control valve 227 may be positioned between the water purification system 240 and the makeup water tank 220. A pump (not depicted) may also be provided to assist in the transfer to the makeup water tank 220. The second control valve 227 may be configured to control a flow rate of the additional purified water stream being added to the makeup water tank 220 through the inlet 216. The second control valve 227 may be controlled by a controller 270. For example, the controller 270 may receive notification regarding the water level within the makeup water tank dropping below a threshold level and providing an instruction to open the control valve 227 to transfer additional water to the makeup water tank 220.

[0063] In certain examples, the makeup water tank 220 may have a return or recirculation line 241 to the water purification system 240. This may be advantageous is recirculating and / or retreating water within the system (e.g., from the cathode separator) before the water source is returned to the electrolyzer. A control valve 242 may be positioned within the return line 241 to control the flow rate of water from the makeup water tank 220 to the water purification system 240.

[0064] In certain examples, the at least one controller 270 of the system 200 may be configured to send a signal to the control valve 242 to control the flow rate of the purified water stream from the makeup water tank toward the water purification system 240.

[0065] In certain examples, the water purification system 240 may be configured to be in direct fluid connection with the anode separator 230, the anodic inlet 104 of the electrochemical stack 100, and / or the cathodic inlet of the electrochemical stack 100 (not illustrated). In other words, the purified water stream may be transferred out of the water purification system 240 to the anode separator 230 or the anodic / cathodic inlet of theelectrochemical system to be combined with recycled water retrieved from the anode outlet of the electrochemical stack. Alternatively, while not depicted, the purified water stream may be provided or returned to the electrochemical stack on the cathode side of the stack as a cooling water source for the cathode side of the stack.

[0066] In certain examples, the system 200 may further include a controller 270 and a data acquisition unit 272. The controller 270 is in communication with the pressure sensors, level sensors (i.e., the first level sensor 223 and the second level sensor 225), the control valves (e.g., control valve 211, control valve 213, control valve 215, and / or control valve 227), the pump 219, the water purification system 240, and any additional sensors within the system. The controller 270 may be configured to control the water purification system 240 to purify the water stream received from the water source 250 to become a purified water stream. The controller 270 may also be configured to receive water level measurements of the cathode separator and makeup water tank from the level sensors 223 and 225, respectively. Additionally, the controller 270 may be configured to control the control valve 213 to control the flow rate of the hydrogen gas flowing out of the first outlet 207 while controlling or maintaining the operating pressure within the cathode separator 210. Further, the controller 270 may be configured to control the control valve 215 to control the flow rate of the hydrogen gas flowing out of the vent or transfer port 205 while controlling or maintaining the operating pressure within the makeup water tank 220. The controller 270 may also be configured to control the control valves 211, 227, and 228 to control the water levels within the cathode separator and makeup water tank as well as the flow rate of fluid flowing through the system 200. Furthermore, the controller 270 may be configured to control the pump to transfer the fluid out of the makeup water tank to the anode separator 230 and pressurize the anode separator 230. The data acquisition unit TIT may be operable to measure, monitor, and / or receive system data and water purification system data in real-time.

[0067] In another example, the system 200 may include a gas supply system 300 in communication with the makeup water tank 220. Such a system is advantageous in transferring gas to the makeup water tank in order to maintain a minimum operatingpressure within the tank and avoid the potential introduction of an outside contaminant into the makeup water tank 220.

[0068] In certain examples, the gas supply system 300 may include a gas cylinder 302 containing an inert gas. The gas supply system 300 may further include a pressure sensor or pressure indicator transmitter 304 configured to measure and transmit a pressure reading of the inert gas. The inert gas in the gas cylinder may be any inert gas and is not limited to the specific gas examples disclosed herein. In certain examples, the inert gas may include nitrogen. In one example, the inert gas may be 2% oxygen in nitrogen.

[0069] The gas supply system 300 may further include a control valve 306 configured to control or regulate the pressure of the gas and control a flow of the gas exiting an outlet 310 of the gas supply system 300. In certain examples, the control valve 306 may actively control the pressure via an interaction with the pressure sensor 304 and a controller, wherein the pressure sensor 304 transmits the pressure reading to the controller, which in turn provides a signal to the control valve 306 to open or close the valve. Alternatively, the control valve 306 may passively control pressure via a spring actuated pressure regulator.

[0070] The inert gas is transferred out of the gas supply system 300 and into the makeup water 220 through the third inlet 221. The gas supply system 300 advantageously pressurizes the makeup water tank 220 or maintains a positive pressure greater than atmospheric pressure, therein preventing any contaminants from entering the makeup water tank 220. Additionally, the gas supply system 300, may advantageously help maintain a minimum or constant flow of gas exiting through the vent or transfer port 205.

[0071] In another embodiment, the gas supply system 300 may be in communication with the controller 270 and the data acquisition unit 272. In other words, the controller 270 is further configured to control the operation of the gas supply system 300. The data acquisition unit 272 is operable to measure, monitor, and / or receive gas supply system data in real-time. Furthermore, the controller 270 is configured to control the pressure and flow of the gas into the system 200 based on the gas supply system data measured, monitored, and / or received by the data acquisition unit 272. It may be advantageous for the gas supply system 300 to be in communication with the controller 270 and the data acquisition unit 272 to periodically and remotely provide (e.g., supply when desired) gas to the system 200.In other words, the gas is automatically transferred into the system 200 to maintain a positive pressure greater than atmospheric pressure, therein preventing any contaminants from entering the makeup water tank 220.

[0072] Figure 3 depicts a flowchart describing a method for separating fluid from a cathode side of an electrolyzer into hydrogen gas and water. In act S101, the cathode separator 210 of the system 200 receives fluid from the cathodic outlet 102 of the electrochemical stack 100 including hydrogen gas and water with a portion of hydrogen gas dissolved within the water.

[0073] In act S103, the cathode separator 210 separates the fluid into a first stream and a second stream. The first stream is primarily or a majority (e.g., at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99%) of hydrogen gas and the second stream including water and the remaining amount of hydrogen gas dissolved in the water.

[0074] In act S105, the makeup water tank 220 receives the second stream of fluid from the outlet of the cathode separator 210 through the first inlet 214.

[0075] In act S107, the makeup water tank 220 separates at least a portion of the dissolved hydrogen from the water in the second stream via a reduction or drop in pressure from the cathode separator 210 to the makeup water tank 220 to provide a purified water stream and hydrogen gas.

[0076] In an optional act S109, the gas supply system 300 may provide an inert gas to the makeup water tank 220 to pressurize the makeup water tank 220 or maintain a positive pressure greater than atmospheric pressure, therein preventing one or more contaminants from entering the makeup water tank 220. (The operation of the gas supply system 300 is further described below with reference to Figure 4.)

[0077] In optional act Sill, the water purification system 240 may treat a water stream received from a water source 250 to then provide an additional purified water stream to the makeup water tank 220. (The operation of the water purification system 240 is further described below with reference to Figure 5.)

[0078] In act S113, the separated hydrogen gas within the makeup water tank 220 may be transferred out of the makeup water tank 220. In one example, the hydrogen gas may bevented to atmosphere via the vent / transfer port 205 due to the makeup water tank 220 being at a positive pressure than the ambient pressure. Alternatively, the hydrogen gas is transferred out of the makeup water tank via the transfer port 205 to a further processing vessel or hydrogen gas reservoir to be collected. Additionally, in act S113, the purified water stream is transferred out of the makeup water tank to return to the electrochemical stack (e.g., to the anode separator 230 by the pump 219).

[0079] In act S115, the purified water stream may be transferred from the anode separator back to the electrolyzer 100 through the anodic inlet 104 at a desired pressure and flow rate, therein advantageously collecting water from the outlet of the cathode side of the stack and recycling the water safely back to the anode side of the stack for further processing.

[0080] Figure 4 depicts a flowchart describing the method for pressurizing the system 200 by the gas supply system 300.

[0081] In act S201, the gas supply regulator valve 306 controls the flow and regulates the pressure of the inert gas from the gas cylinder 302 of the gas supply system 300. Specifically, in act S201, the gas supply regulator valve 306 controls the flow of the inert gas leaving the gas cylinder 302.

[0082] In act S203, the inert gas in the gas cylinder 302 is regulated by the gas supply regulator valve 306 to be at a similar pressure or greater pressure as the makeup water 220 of the system 200. Therefore, the makeup water tank 220 may be at a positive pressure or greater pressure than atmospheric pressure.

[0083] In act S205, the inert gas is transferred from the gas supply system 300 into the makeup water tank 220 through the third inlet 221. As mentioned above, the gas supply system 300 advantageously provides a constant pressure of the inert gas to the makeup water tank 220 to help the makeup water tank 220 maintain a positive pressure.

[0084] Figure 5 depicts a flowchart describing the method for adding a purified water stream to the system 200 by the water purification system 240.

[0085] In act S301, the water purification system 240 receives a water stream from an (e.g., external) water source 250. In act S303, the water purification system 240 purifies the water stream received from the water source 250 to become an additional purified waterstream. For instance, the water purification system may be configured to purify the water source 250 by employing filters to eliminate larger particles. The system may additionally or alternatively use an ion exchange process, (e.g., cation and / or anion exchange processes), to eliminate ions or impurities within the water source that might disrupt electrolysis reactions. Reverse osmosis may be applied to remove dissolved salts and / or other impurities. Furthermore, the system may incorporate ultraviolet (UV) treatment or alternative disinfection methods to guarantee effective microbial control. The primary objective is to generate ultra pure water characterized by high resistivity, thereby minimizing conductivity. This is advantageous for preserving the optimal performance of the electrolyzer and preventing corrosion.

[0086] The purified water stream from the water purification system 240 has a water resistivity of at least 1 megaohm*cm (M0hm*cm), at least 2 M0hm*cm, at least 5 M0hm*cm, at least 10 M0hm*cm, in a range of 1-18.2 M0hm*cm, in a range of 2-18.2 M0hm*cm, in a range of 5-18.2 M0hm*cm, or in a range of 10-18.2 M0hm*cm.

[0087] In act S305, the second control valve 227, which is positioned between the water purification system 240 and the makeup water tank 220, controls the flow rate and / or pressure of the purified water stream. Specifically, a controller may provide a signal to the control valve 227 to open or close the valve (e.g., based on a provided / measured level of water within the makeup water tank 220).

[0088] In act S307, when the second control valve 227 is opened, the water purification system 240 transfers the purified water stream to the makeup water tank 220 (e.g., to maintain a minimum water level in the makeup water tank 220).

[0089] Figure 6 illustrates an exemplary system 120 for controlling operation of the fluid separation system 200 (e.g., including a water purification system 240 and the gas supply system 300). The depicted operating system 120 includes the fluid separation system 200 as described above, as well as a monitoring system (e.g., including a data acquisition unit) 121, a workstation 128, and a network 127.

[0090] The monitoring system 121 includes a server 125 and a database 123. The monitoring system 121 may include computer systems and networks of a system operator (e.g., the operator of the system 200). The server database 123 may be configured to storeinformation regarding the operating conditions or setpoints for optimizing the performance of the system 200.

[0091] The monitoring system 121, the workstation 128, and the fluid separation system 200 are coupled with the network 127. The phrase "coupled with" is defined to mean directly connected to or indirectly connected through one or more intermediate components. Such intermediate components may include hardware and / or software-based components. As such, any data collection via control valves, flow meters, pressure regulators, or sensors within the fluid separation system 200 may be transmitted via the connected network to the monitoring system 121 or workstation 128 for analysis.

[0092] The optional workstation 128 may be a general-purpose computer including programming specialized for providing input to the server 125. For example, the workstation 128 may provide settings for the server 125. The workstation 128 may include at least a memory, a processor, and a communication interface.

[0093] Figure 7 illustrates an exemplary server 125 of the system of Figure 6. The server 125 includes a memory 274, a controller or processor 270, and a communication interface 276. The server 125 may be coupled to a database 123 and a workstation 128. The workstation 128 may be used as an input device for the server 125. The communication interface 276 receives data indicative of use inputs made via the workstation 128 or a separate electronic device.

[0094] The controller or processor 270 may include a general processor, digital signal processor, an application specific integrated circuit (ASIC), field programmable gate array (FPGA), analog circuit, digital circuit, combinations thereof, or other now known or later developed processor. The controller or processor 270 may be a single device or combination of devices, such as associated with a network, distributed processing, or cloud computing.

[0095] The controller or processor 270 may also be configured to cause the fluid separation system 200 to: (1) open / close one or more valves to control a water level within the cathode separator or makeup water tank (e.g., control valve 211, control valve 228, and the like); (2) open / close one or more valves to control the pressure within the cathode separator or makeup water tank (e.g., control valve 213, control valve 215, control valve 306, and the like); (3) transfer and pressurize the ultra-purified water stream by the pump219, and / or (4) measure the pressure, and / or flow rate of either the first stream, second stream, the inert gas, or the ultra-purified water stream by the plurality of sensors (e.g., the pressure indicator transmitters 223, 225, 304, and the like) based on the data measured, monitored, and / or received by the data acquisition unit 272.

[0096] The memory 274 may be a volatile memory or a non-volatile memory. The memory 274 may include one or more of a read-only memory (ROM), random access memory (RAM), a flash memory, an electronic erasable program read-only memory (EEPROM), or other type of memory. The memory 274 may be removable from the device 122, such as a secure digital (SD) memory card.

[0097] The communication interface 276 may include any operable connection. An operable connection may be one in which signals, physical communications, and / or logical communications may be sent and / or received. An operable connection may include a physical interface, an electrical interface, and / or a data interface. The communication interface 276 provides for wireless and / or wired communications in any now known or later developed format.

[0098] In the above-described examples, the network 127 may include wired networks, wireless networks, or combinations thereof. The wireless network may be a cellular telephone network, an 802.11, 802.16, 802.20, or WiMax network. Further, the network 127 may be a public network, such as the Internet, a private network, such as an intranet, or combinations thereof, and may utilize a variety of networking protocols now available or later developed including, but not limited to TCP / IP based networking protocols.

[0099] While the non-transitory computer-readable medium is described to be a single medium, the term "computer-readable medium" includes a single medium or multiple media, such as a centralized or distributed database, and / or associated caches and servers that store one or more sets of instructions. The term "computer-readable medium" shall also include any medium that is capable of storing, encoding, or carrying a set of instructions for execution by a processor or that cause a computer system to perform any one or more of the methods or operations disclosed herein.

[0100] In a particular non-limiting example, the computer-readable medium may include a solid-state memory such as a memory card or other package that houses one or morenon-volatile read-only memories. Further, the computer-readable medium may be a random-access memory or other volatile re-writable memory. Additionally, the computer- readable medium may include a magneto-optical or optical medium, such as a disk or tapes or other storage device to capture carrier wave signals such as a signal communicated over a transmission medium. A digital file attachment to an e-mail or other self-contained information archive or set of archives may be considered a distribution medium that is a tangible storage medium. Accordingly, the disclosure is considered to include any one or more of a computer-readable medium or a distribution medium and other equivalents and successor media, in which data or instructions may be stored.

[0101] In an alternative example, dedicated hardware implementations, such as application specific integrated circuits, programmable logic arrays and other hardware devices, may be constructed to implement one or more of the methods described herein. Applications that may include the apparatus and systems of various examples may broadly include a variety of electronic and computer systems. One or more examples described herein may implement functions using two or more specific interconnected hardware modules or devices with related control and data signals that may be communicated between and through the modules, or as portions of an application-specific integrated circuit. Accordingly, the present system encompasses software, firmware, and hardware implementations.

[0102] In accordance with various embodiments of the present disclosure, the methods described herein may be implemented by software programs executable by a computer system. Further, in an exemplary, non-limited embodiment, implementations may include distributed processing, component / object distributed processing, and parallel processing. Alternatively, virtual computer system processing may be constructed to implement one or more of the methods or functionalities as described herein.

[0103] Although the present specification describes components and functions that may be implemented in particular embodiments with reference to particular standards and protocols, the claim scope is not limited to such standards and protocols. For example, standards for Internet and other packet switched network transmission (e.g., TCP / IP, UDP / IP, HTML, HTTP, HTTPS) represent examples of the state of the art. Such standards areperiodically superseded by faster or more efficient equivalents having the same functions. Accordingly, replacement standards and protocols having the same or similar functions as those disclosed herein are considered equivalents thereof.

[0104] A computer program (also known as a program, software, software application, script, or code) may be written in any form of programming language, including compiled or interpreted languages, and it may be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program may be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program may be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

[0105] The processes and logic flows described in this specification may be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows may also be performed by, and apparatus may also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

[0106] As used in this application, the term "circuitry" or "circuit" refers to all of the following: (a)hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and (b) to combinations of circuits and software (and / or firmware), such as (as applicable): (i) to a combination of processor(s) or (ii) to portions of processor(s) / software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

[0107] This definition of "circuitry" applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and / or firmware. The term "circuitry" would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in server, a cellular network device, or other network device.

[0108] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and anyone or more processors of any digital computer. A processor may receive instructions and data from a read only memory or a random-access memory or both. Components of a computer include a processor for performing instructions and one or more memory devices for storing instructions and data. The computer may also include or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Moreover, a computer may be embedded in another device, e.g., a mobile telephone, a personal digital assistant (PDA), a mobile audio player, or a Global Positioning System (GPS) receiver. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and memory devices, including by way of example semiconductor memory devices, e.g., E PROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in, special purpose logic circuitry.

[0109] To provide for interaction with a user, embodiments of the subject matter described in this specification may be implemented on a device having a display, e.g., a CRT (cathode ray tube), LCD (liquid crystal display), or LED (light emitting diode) monitor, for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user may provide input to the computer. Other kinds of devices may be used to provide for interaction with a user as well; for example, feedback provided to the user may be any form of sensory feedback, e.g., visual feedback, auditory feedback, ortactile feedback; and input from the user may be received in any form, including acoustic, speech, or tactile input.

[0110] E mbodiments of the subject matter described in this specification may be implemented in a computing system that includes a back end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, orthat includes a front end component, e.g., a client computer having a graphical user interface or a Web browser through which a user may interact with an implementation of the subject matter described in this specification, or any combination of one or more such back end, middleware, or front end components. The components of the system may be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network ("LAN") and a wide area network ("WAN"), e.g., the Internet.

[0111] The computing system may include clients and servers. A client and server may be remote from each other and may interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship with each other.

[0112] One or more embodiments of the disclosure may be referred to herein, individually and / or collectively, by the term "invention" merely for convenience and without intending to voluntarily limit the scope of this application to any particular invention or inventive concept. Moreover, although specific embodiments have been illustrated and described herein, any subsequent arrangement designed to achieve the same or similar purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, are apparent to those of skill in the art upon reviewing the description.

[0113] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0114] As used herein, "for example," "for instance," "such as," or "including" are meant to introduce examples that further clarify more general subject matter. Unless otherwise expressly indicated, such examples are provided only as an aid for understandingembodiments illustrated in the present disclosure and are not meant to be limiting in any fashion. Nor do these phrases indicate any kind of preference for the disclosed embodiment.

[0115] The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b) and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may be directed to less than all of the features of any of the disclosed embodiments. Thus, the following claims are incorporated into the Detailed Description, with each claim standing on its own as defining separately claimed subject matter.

[0116] It is intended that the foregoing detailed description be regarded as illustrative rather than limiting and that it is understood that the following claims including all equivalents are intended to define the scope of the disclosure. The claims should not be read as limited to the described order or elements unless stated to that effect. Therefore, all embodiments that come within the scope and spirit of the following claims and equivalents thereto are claimed as the disclosure.

Claims

CLAIMS1. A fluid separation system for an electrolyzer, the fluid separation system comprising: a cathode separator configured to receive a fluid from an outlet of a cathode side of the electrolyzer, wherein the cathode separator is configured to separate the fluid into a first stream comprising hydrogen gas and a second stream comprising water and dissolved hydrogen; and a makeup water tank configured to receive the second stream from the cathode separator, wherein the makeup water tank is configured to operate at a pressure that is greater than atmospheric pressure and less than an operating pressure of the cathode separator, wherein the makeup water tank is configured to separate at least a portion of the dissolved hydrogen from the water via a reduction in pressure from the cathode separator to the makeup water tank to provide a purified water stream and hydrogen gas, and wherein the hydrogen gas from the makeup water tank is configured to be transferred out of the makeup water tank, and wherein the purified water stream is configured to be transferred out of an outlet of the makeup water tank to the electrolyzer.

2. The fluid separation system of claim 1, further comprising: an anode separator configured to receive the purified water stream from the outlet of the makeup water tank and transfer the purified water stream to an anode side of the electrolyzer.

3. The fluid separation system of claim 2, wherein the makeup water tank is configured to operate at an intermediate pressure between the operating pressure of the cathode separator and an operating pressure of the anode separator.

4. The fluid separation system of claim 2, further comprising: a water polishing system configured to receive a portion of the purified water stream from the outlet of the makeup water tank prior to the anode separator and return the portion of the purified water stream to the makeup water tank following treatment of impurities within the purified water stream.

5. The fluid separation system of claim 1, further comprising: a control valve positioned between the cathode separator and the makeup water tank, wherein the control valve is configured to control a flow of the second stream from the cathode separator to the makeup water tank, and / or wherein the control valve is configured to control a level of the water and the dissolved hydrogen within the cathode separator.

6. The fluid separation system of claim 1, wherein the makeup water tank is configured to operate at a positive pressure greater than atmospheric pressure such as to prevent a contaminant from entering into the makeup water tank.

7. The fluid separation system of claim 1, further comprising: a control valve positioned downstream of the makeup water tank, wherein the control valve is configured to control a flow rate of the hydrogen gas transferring out of the makeup water tank, and / or wherein the control valve is configured to control the pressure within the makeup water tank.

8. The fluid separation system of claim 1, further comprising: a control valve positioned between the makeup water tank and an anode separator, wherein the control valve is configured to control a flow rate of the purified water stream gas to the anode separator, and / orwherein the control valve is configured to control a water level within the makeup water tank.

9. The fluid separation system of claim 1, further comprising: a water purification system configured to receive a water stream and treat the water stream, therein providing an additional purified water stream; and a control valve positioned between the water purification system and the makeup water tank, wherein the control valve is configured to control a flow rate and / or pressure of the additional purified water stream to the makeup water tank, and / or wherein the control valve is configured to control a water level within the makeup water tank.

10. The fluid separation system of claim 9, wherein the additional purified water stream from the water purification system has a water resistivity of at least 2 Megaohms*cm.

11. The fluid separation system of claim 9, further comprising: a return line connecting the makeup water tank and the water purification system; and a control valve positioned in the return line and configured to control a flow rate of water from the makeup water tank to the water purification system.

12. The fluid separation system of claim 1, further comprising: a gas supply system configured to provide an inert gas to the makeup water tank to pressurize the makeup water tank or maintain a positive pressure greater than atmospheric pressure, therein preventing a contaminant from entering the makeup water tank.

13. The fluid separation system of claim 12, wherein the gas supply system comprises: a gas cylinder comprising the inert gas; and a control valve positioned between the gas cylinder and the makeup water tank, wherein the control valve is configured to control a pressure of the inert gas and control a flow of the inert gas into the makeup water tank.

14. The fluid separation system of claim 12, wherein the inert gas comprises nitrogen.

15. The fluid separation system of claim 1, further comprising: at least one controller configured to perform at least one of the following: control a pressure of the cathode separator and / or a flow rate of the first stream out of the cathode separator via an adjustment to a vent valve of the cathode separator; control a flow rate of the second stream from the cathode separator to the makeup water tank via an adjustment to a control valve positioned between the cathode separator and the makeup water tank; control a level of the water and the dissolved hydrogen within the cathode separator via an adjustment to the control valve positioned between the cathode separator and the makeup water; control a flow rate of the purified water stream from the makeup tank toward a water purification system via a control valve positioned between the makeup water tank and the water purification system; control a pressure of the makeup water tank and / or a flow rate of the hydrogen gas out of the makeup water tank via an adjustment to a vent valve of the makeup water tank; control a flow rate of the purified water stream out of the makeup water tank via an adjustment to a control valve positioned downstream of the makeup water tank;control a flow rate of the purified water stream out from the makeup water tank toward a water polishing system via a control valve positioned between the makeup water tank and the water polishing system; and / or control a water level within the makeup water tank via an adjustment to the control valve positioned downstream of the makeup water tank.

16. The fluid separation system of claim 15, wherein the at least one controller is further configured to: control a pressure of an inert gas and / or a flow rate of the inert gas to the makeup water tank, and / or control a pressure of a purified water stream and / or a flow rate of the purified water stream to the makeup water tank.

17. A method for separating a fluid produced within an electrochemical system, the method comprising: receiving, by a cathode separator of the electrochemical system, a fluid from an outlet of a cathode side of an electrochemical stack of the electrochemical system; separating, by the cathode separator, the fluid into a first stream comprising hydrogen gas and a second stream comprising water and dissolved hydrogen; receiving, by a makeup water tank of the electrochemical system, the second stream from the cathode separator, separating, by the makeup water tank, at least a portion of the dissolved hydrogen from the water via a reduction in pressure between the cathode separator and the makeup water tank to provide a purified water stream and hydrogen gas; and transferring the purified water stream out of an outlet of the makeup water tank to the electrochemical stack, wherein the makeup water tank is configured to operate at a pressure that is greater than atmospheric pressure and less than an operating pressure of the cathode separator.

18. The method of claim 17, further comprising: receiving, by an anode separator of the electrochemical system, the purified water stream from the outlet of the makeup water tank; and transferring the purified water stream to an anode side of the electrochemical stack.

19. The method of claim 18, wherein the makeup water tank operates at an intermediate pressure that is between the operating pressure of the cathode separator and an operating pressure of the anode separator.

20. The method of claim 18, further comprising: controlling, by a control valve positioned between the makeup water tank and a water polishing system, a flow rate of a portion of the purified water stream out of the makeup water tank toward the water polishing system; treating the portion of the purified water stream within the water polishing system to remove impurities within the portion of the purified water stream; and returning the treated portion of the purified water stream to the makeup water tank.

21. The method of claim 17, further comprising: controlling, by a control valve positioned between the cathode separator and the makeup water tank, a flow rate of the second stream from the cathode separator to the makeup water tank and / or controlling, by the control valve, a level of the water and the dissolved hydrogen within the cathode separator.

21. The method of claim 17, wherein the makeup water tank operates at the pressure greater than atmospheric pressure such as to prevent a contaminant from entering into the makeup water tank.

22. The method of claim 17, further comprising: controlling, by a control valve positioned downstream of the makeup water tank, a flow rate of the hydrogen gas transferring out of the makeup water tank, and / or controlling, by the control valve, a pressure of the makeup water tank.

23. The method of claim 17, further comprising: controlling, by a control valve positioned between the makeup water tank and an anode separator, a flow rate of the purified water stream gas to the anode separator, and / or controlling, by the control valve, a water level within the makeup water tank.

24. The method of claim 17, further comprising: receiving, by a water purification system, a water stream from an external water source; treating, by the water purification system, the water stream to provide an additional purified water stream; and controlling, by a control valve, a flow rate and / or a pressure of the additional purified water stream to the makeup water tank.

25. The method of claim 24, wherein the additional purified water stream has a water resistivity of at least 2 Megaohms*cm.

26. The method of claim 17, further comprising: controlling, by a control valve positioned between the makeup water tank and a water purification system, a flow rate of a portion of the purified water stream out of the makeup water tank to the water purification system;27. The method of claim 17, further comprising: providing, by a gas supply system, an inert gas to the makeup water tank to pressurize the makeup water tank or maintain a positive pressure greater than atmospheric pressure, therein preventing a contaminant from entering the makeup water tank.

28. The method of claim 27, wherein the gas supply system comprises: a gas cylinder comprising the inert gas; and a control valve positioned between the gas cylinder and the makeup water tank, wherein the control valve controls a pressure of the inert gas and / or a flow rate of the inert gas into the makeup water tank.

29. The method of claim 27, wherein the inert gas comprises nitrogen.

Images