Pollution mitigation system for use in electrolysis system

Abstract

The electrolysis system includes an electrolysis cell stack and a pollution mitigation system. The electrolytic cell stack includes an injection port in fluid connection with a cathode chamber of the electrolytic cell stack. The pollution mitigation system is configured to remove ions from the electrolysis cell stack to mitigate ionic pollution in the electrolysis cell stack. The pollution mitigation system includes a storage tank containing formic acid therein, and an injection line fluidly coupled between the storage tank and an injection port. The injection line is configured to direct formic acid from the storage tank to the injection port for injection into the cathode chamber of the electrolytic cell stack.

Description

Cross-references to related applications

[0001] Pursuant to 35 119(e) of the United States Code and any other applicable laws or regulations, this non-provisional application claims the benefit and priority of U.S. Provisional Patent Application Serial No. 63 / 683,320, filed August 15, 2024, the entire contents of which are hereby expressly incorporated by reference. Technical Field

[0002] This disclosure relates to a contamination mitigation system for use in an electrolysis system and a method of using the contamination mitigation system. Background Technology

[0003] Electrolysis systems are known for their efficient use of water and electricity to produce hydrogen and oxygen. Contaminants and / or impurities can impair the operation of an electrolysis system. Typically, passive filters and / or deionizers can be used to remove contaminants and / or impurities from the electrolysis system. However, such methods may be insufficient to ensure that the electrolyzer can operate for extended periods without undergoing multiple maintenance cycles or without reducing hydrogen and oxygen costs. Therefore, more efficient removal of contaminants and / or impurities from the electrolysis system may be advantageous.

[0004] This disclosure relates to a contamination mitigation system for use in an electrolysis system and a method for removing contaminants and / or impurities from the electrolysis system using the contamination mitigation system. Summary of the Invention

[0005] To meet these and other needs, embodiments of this disclosure are included herein.

[0006] In one aspect described herein, an electrolysis system includes an electrolytic cell stack and a contamination mitigation system. The electrolytic cell stack includes an injection port fluidly connected to the cathode chamber of the electrolytic cell stack. The contamination mitigation system is configured to remove ions from the electrolytic cell stack to mitigate ionic contamination in the electrolytic cell stack. The contamination mitigation system includes: a storage tank containing formic acid; an injection line fluidly connected between the storage tank and the injection port; and a pump connected to the injection line and configured to guide formic acid from the storage tank to the injection port for injection into the cathode chamber of the electrolytic cell stack.

[0007] In some embodiments, the contamination mitigation system may further include a mixer located downstream of the storage tank and configured to receive formic acid from the storage tank and water from a tank contained in the electrolysis system to dilute the formic acid in the mixer and form a formic acid solution. In some embodiments, the contamination mitigation system may further include a bypass valve located between the storage tank and the mixer. In some embodiments, the injection line may include: a first branch injection line configured to guide formic acid from the storage tank through the bypass valve and directly to the injection port without flowing through the mixer; and a second branch injection line configured to guide formic acid from the storage tank through the bypass valve, through the mixer, and to the injection port.

[0008] In some embodiments, the electrolysis system may further include: a control system that communicates with a contamination mitigation system and is configured to adjust the concentration of the formic acid solution; and a sensor that maintains fluid communication with the electrolyzer stack to measure water conductivity data relating to water entering the electrolyzer stack. In some embodiments, the control system may communicate with the sensor to receive water conductivity data therefrom. In some embodiments, the control system may be configured to adjust the concentration of the formic acid solution based at least in part on the water conductivity data.

[0009] In some embodiments, the contamination mitigation system may further include a recirculation line extending between the outlet of the electrolyzer stack and a storage tank, and a three-way valve connected to the recirculation line between the outlet and the storage tank. In some embodiments, the three-way valve may be configured to guide formic acid from the outlet to the storage tank via the recirculation line when the three-way valve is in a first position, and the three-way valve may be configured to guide formic acid from the outlet to a high-pressure water separator included in the electrolysis system when the three-way valve is in a second position different from the first position.

[0010] In some embodiments, the electrolysis system may further include: a control system that communicates with a contamination mitigation system and is configured to control the injection of formic acid into the cathode chamber of the electrolyzer stack; and a sensor that maintains fluid communication with the electrolyzer stack to measure water conductivity data related to water entering the electrolyzer stack. In some embodiments, the control system may communicate with the sensor to receive water conductivity data therefrom. In some embodiments, the control system may be configured to regulate the injection of formic acid into the cathode chamber based at least in part on the water conductivity data.

[0011] In some embodiments, the contamination mitigation system may further include a filter located upstream of the storage tank and configured to filter formic acid. In some embodiments, the storage tank may include a pressure-reducing valve configured to control pressure buildup resulting from the decomposition of formic acid in the storage tank.

[0012] In another aspect described herein, a method includes: providing an electrolytic cell stack including an injection port fluidly connected to a cathode chamber of the electrolytic cell stack; injecting formic acid into the cathode chamber of the electrolytic cell stack via the injection port; and removing ions from the electrolytic cell stack via formic acid to mitigate ion contamination in the electrolytic cell stack.

[0013] In some embodiments, the method may further include: guiding formic acid from a storage tank to the cathode chamber of the electrolytic cell stack prior to the injection step. In some embodiments, the method may further include: guiding formic acid from the storage tank through the bypass valve and directly into the cathode chamber of the electrolytic cell stack when the bypass valve located between the storage tank and the injection port is in a first position. In some embodiments, the method may further include: guiding formic acid from the storage tank through the bypass valve and into the mixer when the bypass valve is in a second position different from the first position.

[0014] In some embodiments, the method may further include: directing water from a water tank to a mixer and diluting formic acid with water in the mixer to form a formic acid solution injected into the cathode chamber. In some embodiments, the method may further include: receiving water conductivity data related to the water entering the electrolyzer stack; and adjusting the concentration of the formic acid solution injected into the cathode chamber of the electrolyzer stack based at least in part on the water conductivity data.

[0015] In some embodiments, the method may further include: receiving water conductivity data related to water entering the electrolyzer stack; and adjusting the injection of formic acid into the cathode chamber of the electrolyzer stack based at least in part on the water conductivity data. In some embodiments, the step of injecting formic acid may include manually injecting formic acid into the cathode chamber of the electrolyzer stack via an injection port. In some embodiments, the method may further include guiding formic acid to the cathode chamber of the electrolyzer stack via a pump. Attached Figure Description

[0016] Figure 1A This is a perspective view of the electrolytic cell stack according to this disclosure;

[0017] Figure 1B It is configured to utilize Figure 1A A schematic diagram of the electrolysis system of the electrolytic cell battery stack;

[0018] Figure 1C yes Figure 1B A schematic diagram of an additional part of the electrolysis system;

[0019] Figure 2 This is a schematic diagram of a simplified electrolysis system including a carbon filter and a deionizer;

[0020] Figure 3 This is a schematic diagram of an electrolysis system, which includes a contamination mitigation system configured to remove ions from an electrolytic cell stack;

[0021] Figure 4 yes Figure 3 An enlarged view of a portion of the electrolysis system;

[0022] Figure 5 yes Figure 3 A schematic diagram of an electrolysis system, which includes different contamination mitigation systems configured to remove ions from an electrolytic cell stack; and

[0023] Figure 6 yes Figure 3 A schematic diagram of an electrolysis system, which includes different contamination mitigation systems configured to remove ions from an electrolytic cell stack. Detailed Implementation

[0024] like Figure 1A and Figure 1B As shown, the electrolysis system 10 is typically configured to use water and electricity to produce hydrogen and oxygen. The electrolysis system 10 typically includes one or more electrolyzer cells 80 that use electricity to produce substantially pure hydrogen 13 and oxygen 15 from deionized water 30 through a chemical process. The power source for the electrolysis system 10 is typically derived from an electrical or power generation system, including renewable energy systems for producing green hydrogen, such as wind, solar, hydropower, and geothermal sources. In turn, the pure hydrogen produced by the electrolysis system 10 is typically used as fuel or energy in those power generation systems, such as fuel cell systems. Alternatively, the pure hydrogen produced by the electrolysis system 10 can be stored for later use.

[0025] A typical electrolyzer cell 80 or electrolytic cell consists of multiple components that are compressed and bundled together to form a single unit; multiple electrolyzer cells 80 can be stacked on top of each other, together with the bipolar plates (BPPs) 84, 85 between them, to form an electrolyzer cell stack (e.g. Figure 1B The electrolytic cell stacks 11 and 12 in the electrolysis system 10 can each accommodate multiple electrolytic cells 80 connected in series and / or in parallel. The number of electrolytic cell stacks 11 and 12 in the electrolysis system 10 can vary depending on the amount of power required to meet the power demand of any load (e.g., a fuel cell stack). The number of electrolytic cells 80 in the electrolytic cell stacks 11 and 12 can vary depending on the amount of power required to operate the electrolysis system 10 (including the electrolytic cell stacks 11 and 12).

[0026] Electrolyzer cell 80 includes a multi-part membrane electrode assembly (MEA) 81 having an electrolyte 81E, an anode 81A, and a cathode 81C. Typically, the anode 81A, cathode 81C, and electrolyte 81E of the MEA 81 are configured in a multi-layered arrangement to activate an electrochemical reaction through contact between water and one or more gas diffusion layers 82, 83, thereby producing hydrogen and / or oxygen. Gas diffusion layers (GDL) 82, 83, also referred to as porous transport layers (PTL), are typically located on one or both sides of the MEA 81. Bipolar plates (BPP) 84, 85 are typically located on both sides of the GDL and separate the individual electrolyzer cells 80 of the electrolyzer cell stacks 11, 12 from each other. A bipolar plate 85, together with adjacent gas diffusion layers 82, 83 and MEA 81, can form a repeating unit 88.

[0027] like Figure 1B and Figure 1C As shown, the exemplary electrolysis system 10 may include two electrolytic cell stacks 11 and 12 and a fluid circuit 10FC, which includes... Figure 1B and 1C The various fluid channels shown are configured to deliver, inject, and discharge fluids and other components into, from, and from the electrolysis system 10. Those skilled in the art will understand that the electrolysis system 10 may utilize one or more components within the fluid loop 10FC, and more or fewer than two electrolytic cell stacks 11, 12. For example, the electrolysis system 10 may include one electrolytic cell stack 11, and in other examples, the electrolysis system 10 may include three or more electrolytic cell stacks.

[0028] Electrolysis system 10 may include one or more types of electrolyzer battery stacks 11, 12. In the illustrated embodiment, stacks 11, 12 may use polymer electrolyte membrane (PEM) electrolyzer cells 80. PEM electrolyzer cells 80 typically operate at temperatures from about 4°C to about 150°C (including any specific temperature or temperature range contained therein). PEM electrolyzer cells 80 also typically operate at pressures of about 100 bar or lower, but pressures up to about 1000 bar are also possible (including any specific pressure or pressure range contained therein), which reduces the total energy demand of the system. The standard electrochemical reaction for hydrogen production that occurs in the PEM electrolyzer cell 80 is as follows. • Anode: 2H₂O → O₂ + 4H₂O + +4e Cathode: 4H + +4e→2H2 • Overall: 2H₂O (liquid) → 2H₂ + O₂

[0029] Alternatively, a solid oxide electrolyzer battery 80 may be used in the electrolysis system 10. The solid oxide electrolyzer battery 80 will operate at a temperature of about 500°C to about 1000°C (inclusive of any particular temperature or temperature range therein). The standard electrochemical reaction for hydrogen production that occurs in the solid oxide electrolyzer battery 80 is as follows. • Anode: 2O 2 →O2+4e Cathode: 2H₂O + 4e⁻ → 2H₂ + 2O 2 • Overall: 2H₂O (liquid / vapor) → 2H₂ + O₂

[0030] In addition, an AEM electrolyzer battery 80 using an alkaline medium can also be utilized. An exemplary AEM electrolyzer battery 80 is an alkaline electrolyzer battery 80. The alkaline electrolyzer battery 80 uses an aqueous solution as the electrolyte, such as potassium hydroxide (KOH) and / or sodium hydroxide (NaOH) solution. The alkaline electrolyzer battery 80 typically operates within an operating temperature range of about 0°C to about 150°C (inclusive of any particular temperature or temperature range therein). The alkaline electrolyzer battery 80 typically operates within a pressure range of about 1 bar to about 100 bar (inclusive of any particular pressure or pressure range therein). The typical electrochemical reaction that produces hydrogen in the alkaline electrolyzer battery 80 is as follows. • Anode: 4OH → O2 + 2H2O + 4e Cathode: 4H₂O + 4e⁻ → 2H₂ + 4OH⁻ Overall: 2H₂O → 2H₂ + O₂

[0031] like Figure 1B As shown, the electrolyzer battery stacks 11 and 12 include one or more electrolyzer cells 80 that use electricity to produce substantially pure hydrogen and oxygen from water through a chemical process. In turn, the pure hydrogen produced by the electrolyzer can be used as fuel or energy. Figure 1B As shown, the electrolyzer battery stacks 11 and 12 output the generated hydrogen gas to the hydrogen separator 16 along the fluid connection line 13, and also output the generated oxygen gas to the oxygen separator 14 along the fluid connection line 15.

[0032] Hydrogen separator 16 can be configured to output pure hydrogen and also discharge additional output fluid to hydrogen discharge tank 20, which in turn discharges the fluid to deionized water discharge pipe 21. Oxygen separator 14 can discharge fluid to oxygen discharge tank 24, which in turn discharges the fluid to deionized water discharge pipe 25. Those skilled in the art will understand that specific inputs and outputs of fluids can be pure water or other fluids, such as coolants or byproducts of chemical reactions in the electrolyzer battery stacks 11, 12. For example, oxygen and hydrogen can flow from battery stacks 11, 12 to the respective separators 14, 16. System 10 may also include a rectifier 32 configured to convert the electricity 33 flowing to battery stacks 11, 12 from alternating current (AC) to direct current (DC).

[0033] Deionized water discharge pipes 21 and 25 each output to a deionized water tank 40, which is part of the polishing circuit 36 ​​in the fluid circuit 10FC. Figure 1C As shown. When ionized water interacts with the internal components of the electrolyzer battery stacks 11 and 12, the ionized water can damage the electrolyzer battery stacks 11 and 12. Figure 1C In more detail, the polishing circuit 36 ​​is configured to deionize water so that it can be used in battery stacks 11 and 12 without damaging them.

[0034] In the illustrated embodiment, the deionized water tank 40 outputs fluid, specifically water, to the deionized water polishing pump 44. The deionized water polishing pump 44 then outputs the water to the water polishing heat exchanger 46 for polishing and treatment. The water then flows to the deionized water resin tank 48.

[0035] The coolant is directed through the electrolysis system 10, specifically through a deionized water heat exchanger 72 fluidly connected to the oxygen separator 14. The coolant used to cool the water stream can also subsequently be fed via coolant inlet pipe 27 into a water polishing heat exchanger 46 for polishing. The coolant is then returned to the deionized water heat exchanger 72 to cool the water therein.

[0036] After water exits from the deionized water polishing heat exchanger 46 and subsequently enters the deionized water resin tank 48, a portion of the water can be fed to the deionized water high-pressure supply pump 60. Another portion of the water can be fed to the deionized water pressure control valve 52, such as... Figure 1C As shown. The portion of water fed into the deionized water pressure control valve 52 flows through the recirculation fluid connection pipe 54, which allows the water to flow back to the ionization tank 40 for continued polishing.

[0037] In some embodiments, the electrolysis system 10 may be equipped with a deionized water skid for polishing the water flow, thereby rinsing away ions from the water more quickly. This portion of the water fed into the deionized water high-pressure supply pump 60 is then output to the deionized water supply pipe 64, subsequently flowing into the oxygen separator 14 for recirculation, and ultimately reused in the electrolyzer battery stacks 11, 12. This process can then be repeated continuously.

[0038] The electrolysis system 10 described herein can be used in stationary and / or immobile power systems, such as industrial applications and power plants. The electrolysis system 10 can also be implemented in combination with other electrolysis systems 10.

[0039] The electrolysis system 10 can be included in mobile applications. The electrolysis system 10 can be located in a vehicle or powertrain. The vehicle or powertrain including the electrolysis system 10 can be an automobile, a motor vehicle, a bus, a truck, a train, a locomotive, an aircraft, a light vehicle, a medium vehicle, or a heavy vehicle.

[0040] This disclosure provides a contamination mitigation system 214 for use in an electrolysis system 210, such as Figure 3 and Figure 4 As shown. The electrolysis system 210 includes an electrolytic cell stack 212 and a contamination mitigation system 214. The electrolytic cell stack 212 includes an inlet 218 and an injection port 220 opposite to the inlet 218. The electrolytic cell stack 212 can be the aforementioned electrolytic cell stacks 11 and 12.

[0041] Impurities and / or contaminants can impair the operation of an electrolysis system (such as electrolysis system 210). In some electrolysis systems 110, passive filters 114 (such as carbon filters) or deionizers 116 can be used to remove impurities and / or contaminants, such as... Figure 2 As shown. However, such methods may not be sufficient to ensure that the electrolyzer battery can operate for a long time without undergoing multiple maintenance cycles (i.e., filter replacement) or without reducing the cost of hydrogen and oxygen (i.e., by relaxing the requirements for water purity, since system materials in contact with water may release harmful substances).

[0042] Pollutants can include any or any combination of ions, organic matter, inorganic matter, particulate matter, and biological agents. Ions can include any or any combination of titanium (from bipolar plates and / or porous transport layers), iron, chromium, nickel (from steel), and copper. Biological agents can include bacteria, molds, yeasts, etc.

[0043] Specifically, ions affect the performance losses (kinetic losses, ohmic losses, and / or mass transfer losses) of the electrolysis system 110 and can influence product purity and electrolyzer degradation. For example, ions can accumulate in the membrane of the electrolyzer cell over time, and these ions can have adverse effects on the membrane. Ions can reduce the amount of water in the membrane, thereby increasing the membrane resistance. Ions can also hinder the transport of oxygen (O2) and / or hydrogen (H2) due to the reduction of water in the membrane. Some ions can accelerate the conversion or decomposition of hydrogen peroxide (H2O2) into free radicals. For example, Ti 3+ or Ti 4+ The H2O2 formed by the permeation of O2 and H2 through the membrane to the catalyst layer can be catalyzed into free radicals, which attack the membrane. Therefore, these free radicals can lead to membrane degradation.

[0044] like Figure 2 As shown, some electrolysis systems 110 include a carbon filter 114, a deionizer 116, and a temperature-switching adsorption (TSA) dryer 118. Filters 114 and deionizer 116 may not be robust enough to capture all ions. Specifically, these components may be insufficient to mitigate the dissolution of residues from the construction of the electrolyzer or contaminants resulting from material degradation, such as corrosion. Furthermore, contaminant buildup may occur if filters 114 and deionizer 116 reach their storage capacity due to missed maintenance cycles. Additionally, filters 114 and deionizer 116 are used to remove ions from the water flowing through the electrolysis system 110. However, filters 114 and deionizer 116 do not remove ions accumulated in the ionomers of the membranes and catalyst layers of the electrolyzer cells.

[0045] Some electrolysis systems 110 include a water pump 120 for treating water, a carbon filter 114 and a deionizer 116, a water tank 122 (i.e., a demister / tank), and a radiator 124, such as Figure 2 As shown. An additional deionizer 126 and a deionized water pump 128 are connected to the tank 122 to remove system-generated impurities that accumulate in the tank 122. A recirculation pump 130 is connected to the tank 122 to direct deionized water to the radiator 124 and / or filter 134, and ultimately to the electrolyzer stack 112. For example, during startup and low-power operation, the radiator 124 can be bypassed via a bypass valve 132. Anode-side effluent and cathode-side condensate are recirculated from the electrolyzer stack 112 back to the tank 122.

[0046] Some electrolysis systems 110 also include a high-pressure water separator (HPWS) 136, which receives the hydrogen / water cathode discharge stream from the electrolyzer stack 112, such as... Figure 2As shown. The hydrogen / water cathode effluent flows to HPWS136 to recover liquid water, is cooled in cooler 138 to condense water vapor, and is then sent to TSA dryer 118 for final drying to produce hydrogen products. The water recovered in HPWS136 and cooler 138 is conveyed to low-pressure hydrogen separator (LPHS) 140 to remove dissolved hydrogen, which can be periodically vented to an exhaust chamber or the atmosphere, and the water can be returned to water tank 122. Cooler 138 can cool the hydrogen / water cathode effluent to approximately 30°C.

[0047] To minimize hydrogen loss, the TSA dryer 118 may include at least two adsorption beds, one for drying and the other for regeneration. Regeneration can be accomplished by heating the bed and desorbing water by supplying a high-temperature stream of dry hydrogen heated by an electric heater 142, followed by cooling the bed with a low-temperature hydrogen product. The regeneration loop can use a blower 144, an electric heater 142, and a cooler 146 to cool the hot, wet hydrogen, and a demister 148 to remove condensate after cooling. The cooler 146 can cool the hydrogen product to approximately 30°C. The electric heater 142 can heat the hydrogen stream to approximately 220°C.

[0048] The pollution mitigation system 214 is integrated with the electrolysis system 210, such as Figure 3 As shown. The contamination mitigation system 214 maintains the performance of the electrolysis system 210 by effectively controlling and removing foreign cations from the electrolysis system 210, thereby preventing ionomer degradation of the membrane and catalyst layer and ensuring long-term efficient operation of the system. Compared to the device provided by the electrolysis system 110, the contamination mitigation system 214 includes additional devices for removing foreign cations during operation of the electrolysis system 210.

[0049] During operation of the electrolysis system 210, due to the electric field, foreign cations accumulate at the cathode of the electrolytic cells contained in the electrolytic cell stack 212. The contamination mitigation system 214 promotes the removal of foreign cations by injecting formic acid (HCOOH) 226 into the cathode chamber 212C of the electrolytic cell stack 212 via the injection port 220. Figure 3 As shown. Formic acid 226 helps remove ions accumulated in the ionomers of the membrane and catalyst layers of electrolytic cells.

[0050] The pollution mitigation system 214 includes a formic acid storage tank 224 containing formic acid 226, such as Figure 3As shown. The contamination mitigation system 214 also includes a pump 228, an injection line 229, a first valve 230, a mixer 232, a second valve 234, and / or a bypass valve 244. The pump 228 pumps and / or directs formic acid 226 from the storage tank 224 through the injection line 229 to the mixer 232 and / or the electrolytic cell stack 212. The pump 228 is positioned along the injection line 229 between the storage tank 224 and the first valve 230.

[0051] The first valve 230 is located on the injection line 229 downstream of the pump 228, such as Figure 3 As shown. The first valve 230 can be selectively opened, partially opened, and closed to allow formic acid 226 to be directed from the storage tank 224 to the mixer 232 and / or the electrolytic cell stack 212. The first valve 230 is capable of controlling the amount of formic acid 226 directed to the mixer 232 and / or the electrolytic cell stack 212.

[0052] Bypass valve 244 is schematically a three-way valve, such as Figure 3 As shown. The bypass valve 244 is located on the injection line 229 and defines the first branch injection line 229A and the second branch injection line 229B, as follows. Figure 4 As shown. The first branch injection line 229A extends directly from the bypass valve 244 to the injection port 220. The second branch injection line 229B extends from the bypass valve 244 to the mixer 232, and then to the injection port 220.

[0053] Bypass valve 244 directs formic acid 226 directly to the injection port 220 of the electrolytic cell stack 212 via the first branch injection line 229A, and / or to the first inlet 232A of the mixer 232 via the second branch injection line 229B. Figure 4 As shown. The bypass valve 244 is located downstream of the first valve 230 and upstream of the mixer 232 and the electrolytic cell stack 212. The bypass valve 244 can move between a closed position, a first open position, a second open position, and a third open position. The bypass valve 244 can be in the closed position, preventing formic acid 226 from being directed to the mixer 232 or the electrolytic cell stack 212; it can be in the first open position, directing formic acid 226 only to the mixer 232; it can be in the second open position, directing formic acid 226 only to the electrolytic cell stack 212; or it can be in the third open position, directing formic acid 226 to both the mixer 232 and the electrolytic cell stack 212.

[0054] During operation of the electrolytic cell stack 212, water permeates from the anode chamber 212A to the cathode chamber 212C. This permeation may be exacerbated by the presence of formic acid 226 in the cathode chamber 212C. Therefore, water may already be present in the cathode chamber 212C, diluting the formic acid 226 in the cathode chamber 212C (rather than in the mixer 232 as described below). Consequently, the formic acid 226 may not always need to be diluted in the mixer 232 (as described below) before being directed to the electrolytic cell stack 212. A bypass valve 244 is configured to regulate the injection of formic acid 226 into the electrolytic cell stack 212, thereby allowing partial or complete bypassing of the mixer 232 used for diluting the formic acid 226.

[0055] Mixer 232 receives formic acid 226 from storage tank 224 and water 236 from water tank 238, such as Figure 3 As shown. Formic acid 226 is received by the first inlet 232A of the mixer 232, and water 236 is received by the second inlet 232B, as... Figure 4 As shown. The recirculation pump 239 directs water 236 from the tank 238 to the second inlet 232B of the mixer 232. The second valve 234 can be selectively opened, partially opened, and closed to allow water 236 to be directed to the mixer 232. The second valve 234 can control the amount of water 236 directed to and entering the mixer 232.

[0056] In mixer 232, water 236 and formic acid 226 are mixed to form formic acid solution 222, such as Figure 3 As shown. Water 236 dilutes the concentration of formic acid 226. The concentration of formic acid solution 222 can be adjusted by changing the amount of water 236 and formic acid 226 guided to mixer 232. Then, formic acid solution 222 is guided from outlet 232C of mixer 232 and enters cathode chamber 212C of electrolytic cell stack 212 via injection port 220, as shown. Figure 4 As shown. During the operation of the electrolytic cell stack 212, formic acid solution 222 or formic acid 226 can be guided into the cathode chamber 212C.

[0057] like Figure 3 As shown, the electrolysis system 210 includes a water pump 248, a carbon filter 250, a first deionizer 252, a water tank 238, a second deionizer 254, a deionized water pump 256, a recirculation pump 239, a radiator 258, and / or a particulate filter 260. The water pump 248 directs water through the carbon filter 250 and the first deionizer 252 to treat and filter the water. The water is then directed to the water tank 238. The water tank 238 may include a demister for separating vapor from water. Water in the water tank 238 can be pumped out of the water tank 238, through the deionized water pump 256, through the second deionizer 254, and back into the water tank 238, as shown. Figure 3As shown. The second deionizer 254 removes impurities accumulated in the water tank 238. The water 236 in the water tank 238 can be guided to the inlet 218 of the electrolyzer stack 212 via the recirculation pump 239. The water 236 is used to generate hydrogen and oxygen.

[0058] Water 236 from recirculation pump 239 can flow through radiator 258, through particulate filter 260, and into inlet 218 of electrolytic cell stack 212, or it can bypass radiator 258, flow through particulate filter 260, and enter inlet 218 of electrolytic cell stack 212, as shown below. Figure 3 As shown. A bypass valve 262 is located between the recirculation pump 239 and the radiator 258 / particulate filter 260 to allow water 236 to bypass the radiator 258. Anode-side discharge water and cathode-side condensate are recirculated from the electrolytic cell stack 212 to the water tank 238, as shown. Figure 3 As shown.

[0059] The second valve 234 is located downstream of the bypass valve 262, such as Figure 3 As shown. Water 236 from water tank 238 flows through recirculation pump 239, through bypass valve 262, through second valve 234 and into mixer 232.

[0060] In some embodiments, the electrolysis system 210 further includes a high-pressure water separator (HPWS) 264, a first cooler 266, a temperature-switching adsorption (TSA) dryer 268, a low-pressure hydrogen separator (LPHS) 270, an electric heater 272, a blower 274, a demister 276, and / or a second cooler 278, such as Figure 3 As shown. The hydrogen / water cathode effluent from electrolyzer stack 212, the remaining formic acid solution 222 and / or the remaining formic acid 226 are directed to HPWS 264 to recover water, cooled in first cooler 266 to condense water vapor, and sent to TSA dryer 268 for final drying to produce hydrogen products. First cooler 266 can cool the hydrogen / water cathode effluent to approximately 30°C. The water recovered in HPWS 264 and first cooler 266, the remaining formic acid solution 222 and / or the remaining formic acid 226 are conveyed to LPHS 270 to remove dissolved hydrogen, which can be periodically vented to the effluent chamber or the atmosphere. The recovered water, the remaining formic acid solution 222 and / or the remaining formic acid 226 are returned to water tank 238 and / or directed to inlet 220 of electrolyzer stack 212, as shown. Figure 3 As shown.

[0061] Used formic acid solution 222 and / or formic acid 226 contain cations exchanged from contaminated ionomers in cathode chamber 212C, which ultimately limits the extent of the ion exchange process. In tank 238, a second deionizer 254 can remove unwanted cations from formic acid solution 222 and / or formic acid 226.

[0062] In some embodiments, the pollution mitigation system 214 further includes a bypass valve 246, such as Figure 3 As shown. The bypass valve 246 is located downstream of LPHS 270 and upstream of the inlet 220 of the water tank 238 and the electrolytic cell stack 212. The bypass valve 246 can direct the recovered water, formic acid solution 222, and / or formic acid 226 to the water tank 238, to the electrolytic cell stack 212, or to both. By directing formic acid 226 or formic acid solution 222 from LPHS 270 back to the inlet 220 (facilitated by the bypass valve 246), the cathode chamber 212C contacts formic acid 226 or formic acid solution 222, thereby achieving a wider ion exchange. During this period, water continuously accumulates within the components of the recirculation loop. Therefore, separators 264 and 270, and the demister 276 need to have sufficient volume to accommodate the increase in water volume.

[0063] To minimize hydrogen loss, the TSA dryer 268 may include at least two adsorption beds, one for drying and the other for regeneration. Regeneration can be accomplished by heating the bed and desorbing water by supplying a high-temperature stream of dry hydrogen heated by an electric heater 272, followed by cooling the bed with a low-temperature hydrogen product. The regeneration loop can use a blower 274 and a second cooler 278 to cool the hot, wet hydrogen, and a demister 276 to remove condensate after cooling. The second cooler 278 can cool the hydrogen product to approximately 30°C. The electric heater 272 can heat the hydrogen stream to approximately 220°C.

[0064] In some embodiments, the contamination mitigation system 214 includes a filtration device 280, such as a filter 280, located upstream or downstream of the storage tank 224, for filtering formic acid 226. Figure 4 As shown. Because filter 280 removes and / or filters impurities from formic acid 226, filter 280 allows for the use of formic acid 226 with lower purity in the contamination mitigation system 214. Therefore, filter 280 strikes a balance between the cost and purity of formic acid 226.

[0065] In some embodiments, the storage tank 224 includes a pressure reducing valve 242, such as Figure 4As shown. Concentrated formic acid 226 can slowly decompose into carbon monoxide and water within storage tank 224 (see Equation 9 below). This decomposition can lead to pressure buildup in storage tank 224. Pressure relief valve 242 allows the pressure in storage tank 224 to be released.

[0066] Formic acid 226 has a boiling point of approximately 100.8°C, resulting in a relatively high vapor pressure in the electrolysis system 210. An adsorbent suitable for formic acid 226 can be added to the TSA dryer 268 to minimize losses, thereby avoiding hydrogen contamination and improving cation removal efficiency.

[0067] In some embodiments, formic acid solution 222 and / or formic acid 226 is injected into cathode chamber 212C via injection port 220 at predetermined intervals. In some embodiments, the predetermined interval is one month, such that formic acid solution 222 and / or formic acid 226 is injected monthly. In some embodiments, the predetermined interval is two weeks, such that formic acid solution 222 and / or formic acid 226 is injected every two weeks. In some embodiments, the predetermined interval is greater than one month. The predetermined interval ranges from about one week to about one year, including any interval range or specific interval contained therein. In some embodiments, control system 240 determines the time and frequency of injecting formic acid solution 222 and / or formic acid 226 into cathode chamber 212C.

[0068] In some embodiments, formic acid solution 222 and / or formic acid 226 are injected into cathode chamber 212C via injection port 220 in response to increases in battery voltage, increases in water conductivity, increases in high-frequency resistance, and / or changes in other monitored parameters. For example, control system 240 may determine that foreign cations are accumulating in cathode chamber 212C. In response to determining that foreign cations are accumulating in cathode chamber 212C (e.g., the accumulation amount is equal to or greater than a threshold), control system 240 may activate contamination mitigation system 214 to inject formic acid solution 222 and / or formic acid 226.

[0069] The control system 240 is operably connected to the pollution mitigation system 214 to control the pollution mitigation system 214, such as... Figure 3 As shown. The control system 240 monitors the parameters of the electrolysis system 210 to avoid undesirable events when using formic acid solution 222 and / or formic acid 226, as the introduction of formic acid solution 222 and / or formic acid 226 increases the conductivity of water. The conductivity of water is monitored by sensor 245 included in the contamination mitigation system 214, such as... Figure 4 As shown. Sensor 245 communicates with control system 240 to transmit water conductivity data to control system 240. Sensor 245 detects, measures, or determines water conductivity data related to the water 236 guided into electrolyzer stack 212, such as... Figure 4 As shown.

[0070] The control system 240 communicates with valves 230, 234, 244, and 246 of the pollution mitigation system 214, such as... Figure 4 As shown. The control system 240 can instruct valves 230, 234, 244, and 246 to open, partially open, or close, or to use one of the positions of three-way valves 244 and 246. Furthermore, the control system 240 communicates with pump 228 to control its operation. The control system 240 receives water conductivity data from sensor 245 and, at least in part based on the water conductivity data, operates valves 230, 244, and 246 to increase or decrease the amount of formic acid 226 directed to the electrolytic cell stack 212 or mixer 232. The control system 240 also operates a second valve 234, at least in part based on the water conductivity data, to increase or decrease the amount of water 236 directed to mixer 232. Thus, the control system 240 adjusts the concentration of the formic acid solution 222, at least in part based on the water conductivity data.

[0071] The control system 240 also communicates with the electrolyzer stack 212 to monitor any rise in high-frequency resistance and battery voltage. For example... Figure 4 As shown, the control system 240 receives resistance and voltage data from sensor 247, and, at least in part based on the resistance and / or voltage data, operates valves 230, 244, and 246 to increase or decrease the amount of formic acid 226 directed to the electrolytic cell stack 212 or mixer 232. The control system 240 also operates a second valve 234, at least in part based on the resistance and / or voltage data, to increase or decrease the amount of water 236 directed to the mixer 232. Thus, the control system 240 adjusts the concentration of the formic acid solution 222 at least in part based on the resistance and / or voltage data.

[0072] like Figure 4 As shown, the control system 240 also communicates with the mixer 232 and / or sensor 235 to monitor the concentration of the formic acid solution 222 output by the mixer 232. Based on the data input to the control system 240 (i.e., water conductivity data, resistance data, voltage data, and concentration data), the control system 240 operates valves 230, 234, 244, 246, and pump 228.

[0073] Formic acid solution 222 and / or formic acid 226 are injected into cathode chamber 212C through injection port 220, such as Figure 4 As shown. The concentrations of formic acid solution 222 and / or formic acid 226 should be greater than the concentration of ions in the water. The necessary concentrations of formic acid solution 222 and / or formic acid 226 vary based on the properties of the water (i.e., the degree of impurities in the water). The protons formed during formic acid dissolution (Equation 1) will subsequently undergo exogenous cation exchange (Equation 2) with ionomers in the catalyst layer and sulfonate sites in the membrane. (Equation 2) These foreign cations are then captured by the ion exchange resin of the deion filter.

[0074] Formic acid solution 222 and / or formic acid 226, which did not dissolve via Equation 1, may undergo electrochemical oxidation on the platinum surface at the working cathode potential (Equation 3). Equations 3 through 12 illustrate other reactions occurring within the electrolysis system 210. As shown in Equation 3, protons can be generated via reactions other than those shown in Equation 1. Formic acid solution 222 may also undergo chemical oxidation on the platinum surface (Equation 4), thereby producing H2. Since H2 is flammable when mixed with O2 (therefore, introducing formic acid solution 222 into the anode chamber 212A increases the flammability risk, see Equation 4), it is preferable to introduce formic acid solution 222 into the cathode chamber 212C to minimize safety issues associated with the anode chamber 212A. As shown in Equations 5 through 7, the carbon dioxide produced by the reactions shown in Equations 3 and 4 is a proton (H2O). + Another source of ). HCOOH→CO2+2H + +2e - (E 0 =-0.25V vs RHE) (Equation 3) HCOOH→H2+CO2 (Equation 4)

[0075] The electrochemical oxidation of HCOOH (Equation 3) produces adsorbed carbon monoxide intermediates, which reduces the surface area of ​​the platinum catalyst (Equation 8). The chemical decomposition of HCOOH also produces carbon monoxide (Equation 9), which can then be adsorbed onto the platinum (Equation 10). HCOOH + Pt → Pt-CO ads +H₂O (Equation 8) HCOOH→CO+H2O (Equation 9)

[0076] The effects of carbon monoxide can be chemically mitigated by the diffusion of oxygen through the membrane from the anode chamber 212A. This process is more efficient than that in a proton exchange membrane fuel cell because the significantly higher oxygen partial pressure promotes oxygen diffusion through the membrane (the oxygen partial pressure in a fuel cell is approximately 0.5 bar, while the oxygen partial pressure in an electrolyzer is greater than 30 bar). Equations 11 and 12 use the oxygen present in the anode chamber 212A to mitigate the effects of carbon monoxide buildup. Pt-Oads +Pt-CO ads →2Pt + CO2 (Equation 12)

[0077] The other products of the reactions shown in equations 1, 2, 4, 6, and 7 were captured by a deionization filter ion exchange resin (HCOO). - X m+ HCO3 - CO3 2- Carbon dioxide (H2) can either be emitted (reverse reaction of Equation 5) or decomposed (Equations 6 and 7) and subsequently removed by a deionization filter ion exchange resin. Carbon monoxide and carbon dioxide (Equations 3, 4, 9, and 12) are more readily adsorbed than hydrogen and are captured by the TSA dryer 268. In some embodiments, the TSA dryer 268 may contain specific adsorbents for carbon monoxide and carbon dioxide.

[0078] According to equations 1, 3, 4, 8, and 9, formic acid 226 will decompose. The decomposition of formic acid 226 and its byproducts eliminates the need to flush the electrolytic cell stack 212 with water, simplifying the regeneration process. Therefore, after using the contamination mitigation system 214, the electrolytic cell stack 212 does not require water flushing. Since the electrolytic cell stack 212 does not require water flushing, the process duration using the contamination mitigation system 214 is shortened compared to processes requiring a water flushing step.

[0079] The use of formic acid 226 offers several advantages. Formic acid 226 is a natural product produced by plants, insects, and bacteria, and is biodegradable. As a liquid, it can be stored in large quantities at concentrations exceeding 99% (by weight), significantly reducing the size of storage tanks 224. Furthermore, formic acid 226 is completely miscible with water, allowing for a wide range of concentrations to meet diverse needs. Formic acid 226 does not significantly increase the conductivity of water because it is a weak acid with a pKa value of 3.75 (see Table 1), lower than CH3COOH (acetic acid), similar to H2CO3 (carbonic acid), and much higher than CF3SO3H (trifluoromethanesulfonic acid, a catalyst layer ionomer and membrane substitute). For example, a 2.9 mM HCOOH solution produces 0.63 mM H2SO3. + The concentration (pH value is 3.2) and conductivity are 307 μS / cm. Due to the relative dilution of formic acid solution 222, the temporary efficiency loss caused by shunt current in electrolytic cell stack 212 is also relatively small. Table 1. Acid dissociation constants. acid <![CDATA[pKa1]]> <![CDATA[pKa2]]> <![CDATA[CH3COOH]]> 4.76 - HCOOH 3.75 - <![CDATA[H2CO3]]> 3.6 10.3 <![CDATA[CF3SO3H]]> -14.7 - K a =[A - ][H +] / [HA],pK a =-log(K) a ).

[0080] The concentration of formic acid solution 222 can be varied to meet different requirements because the timescale of the ion exchange process (Equation 2) depends on the concentration of formic acid solution 222. In some embodiments, the concentration of formic acid solution 222 ranges from about 0.01 M to about 10 M, including any specific concentration or concentration range contained therein. The current density can also be varied, although higher values ​​are preferred because they allow foreign ions to concentrate near and within the ionomer of the cathode catalyst layer. Operation under open-circuit conditions is also possible.

[0081] Therefore, as described above in conjunction with Equations 1 to 12, the contamination mitigation system 214 enables the removal of foreign cations during the operation of the electrolyzer stack 212. During the operation of the electrolyzer stack 212, foreign cations accumulate at the cathode due to the electric field, which facilitates ion exchange (Equation 2) by injecting formic acid 226 and / or formic acid solution 222 into the cathode chamber 212C, located near the catalyst ionomer, thereby achieving the removal of foreign cations. This feature is advantageous because downtime at the customer's site should be avoided to maximize the utilization of the electrolyzer.

[0082] Figure 5 Another embodiment of a contamination mitigation system 314 for use in an electrolysis system 310 is shown. The contamination mitigation system 314 and the electrolysis system 310 are substantially similar. Figure 3 and Figure 4 The pollution mitigation system 214 and electrolysis system 210 are shown and described herein. Therefore, similar figure numbers in the 300 series denote common features between pollution mitigation system 314 and electrolysis system 310, and between pollution mitigation system 214 and electrolysis system 210, respectively. The description of pollution mitigation system 214 and electrolysis system 210 is incorporated herein by reference and applies equally to pollution mitigation system 314 and electrolysis system 310, unless it conflicts with the specific disclosure of pollution mitigation system 314 and electrolysis system 310.

[0083] The pollution mitigation system 314 includes an injection port 320 formed in the electrolytic cell stack 312, such as Figure 5 As shown. Inlet 320 is used to inject formic acid solution 322 or formic acid 326 into cathode chamber 312C during maintenance procedures. In this way, formic acid 326 can be diluted before being injected into inlet 320 to form formic acid solution 322. Formic acid solution 322 or formic acid 326 can be injected manually by an operator or technician. Control system 340 communicates with electrolytic cell stack 312, sensors 245, 247, and contamination mitigation system 314, such as... Figure 5As shown. The control system 340 can output instructions to the operator or technician regarding the amount or concentration of the formic acid solution 322 or formic acid 326 to be injected, based on water conductivity data, voltage data, resistance data, and / or data related to previous injections. The control system 340 can store data related to injection time, injection volume, and the concentration of the injected formic acid solution 322 or formic acid 326. The advantage of the contamination mitigation system 314 is that it allows maintenance of the electrolyzer stack 312 without shutting it down, and requires only a minimal number of additional system components.

[0084] Figure 6 Another embodiment of a contamination mitigation system 414 for use in an electrolysis system 410 is shown. The contamination mitigation system 414 and the electrolysis system 410 are substantially similar. Figures 3 to 5 The pollution mitigation systems 214, 314 and electrolysis systems 210, 310 are shown and described herein. Therefore, similar figure numbers in the 400 series indicate common features between pollution mitigation system 414 and electrolysis system 410, and between pollution mitigation systems 214, 314 and electrolysis systems 210, 310. The description of pollution mitigation systems 214, 314 and electrolysis systems 210, 310 is incorporated herein by reference and applies equally to pollution mitigation system 414 and electrolysis system 410, unless it conflicts with the specific disclosure of pollution mitigation system 414 and electrolysis system 410.

[0085] The pollution mitigation system 414 includes an injection port 420 and an outlet 482 formed in the electrolytic cell stack 412, such as Figure 6 As shown. Inlet 420 is used to inject formic acid 226 into cathode chamber 412C. Excess formic acid 426 can be removed from cathode chamber 412C via outlet 482.

[0086] The pollution mitigation system 414 includes a three-way valve 486 located downstream of outlet 482, such as Figure 6 As shown. The three-way valve 486 is configured to, when in the first position, guide formic acid 426 from outlet 482 through the three-way valve 486 and to discharge port 484. The three-way valve 486 is located upstream of discharge port 484 and upstream of HPWS264. When the three-way valve 486 is in the first position, formic acid 426 is prevented from flowing to HPWS264. Instead, formic acid 426 is guided to discharge port 484. The three-way valve 486 is also configured to, when in the second position, guide formic acid 426 from outlet 482 through the three-way valve 486 and to HPWS264.

[0087] The pollution mitigation system 414 also includes a formic acid storage tank 424 that is fluidly connected to the inlet 420, and a pump 428 located between the storage tank 424 and the outlet 484, such as Figure 6As shown. The contamination mitigation system 414 minimizes contact between components of the electrolysis system 410 and formic acid 426 during electrolyzer shutdown. A three-way valve 486 facilitates the recirculation of formic acid 426 through storage tank 424 and pump 428. A recirculation line 459 is formed between and defined by outlet 482, three-way valve 486, pump 428, and storage tank 424. The control system 440 communicates with the electrolyzer stack 412, sensors 245 and 247, and the contamination mitigation system 414, such as... Figure 6 As shown.

[0088] In contamination mitigation systems 214, 314, and 414, liquids other than formic acid 226, 326, and 426 can be used, such as hydrogen peroxide, hydrochloric acid, sulfuric acid, nitric acid, or carbon dioxide. Hydrogen peroxide may not be preferred because it catalyzes ionomer and membrane degradation. Hydrochloric acid may not be preferred because chloride ion contamination can lead to chlorine precipitation, which may reduce the purity of oxygen and hydrogen products. Sulfuric acid may not be preferred because there is a risk of sulfur deposition on the cathode platinum catalyst, clogging active sites. Nitric acid may not be preferred because at the cathode potential, nitrates are reduced to cations, which may interfere with the cleaning process. Carbon dioxide may not be preferred because high-pressure carbon dioxide storage devices are bulky.

[0089] The following aspects of the invention are to be considered and are not limiting:

[0090] A first aspect of the invention relates to an electrolysis system. The electrolysis system includes an electrolytic cell stack and a contamination mitigation system. The electrolytic cell stack includes an injection port fluidly connected to a cathode chamber of the electrolytic cell stack. The contamination mitigation system is configured to remove ions from the electrolytic cell stack to mitigate ion contamination in the electrolytic cell stack. The contamination mitigation system includes: a storage tank containing formic acid; an injection line fluidly connected between the storage tank and the injection port; and a pump connected to the injection line and configured to guide formic acid from the storage tank to the injection port for injection into the cathode chamber of the electrolytic cell stack.

[0091] A second aspect of the invention relates to a method. The method includes: providing an electrolytic cell stack including an injection port fluidly connected to a cathode chamber of the electrolytic cell stack; injecting formic acid into the cathode chamber of the electrolytic cell stack via the injection port; and removing ions from the electrolytic cell stack via the formic acid to mitigate ion contamination in the electrolytic cell stack.

[0092] In a first aspect of the invention, the contamination mitigation system may further include a mixer located downstream of the storage tank and configured to receive formic acid from the storage tank and water from a water tank contained in the electrolysis system to dilute the formic acid in the mixer and form a formic acid solution. In a first aspect of the invention, the contamination mitigation system may further include a bypass valve located between the storage tank and the mixer. In a first aspect of the invention, the injection line may include: a first branch injection line configured to guide formic acid from the storage tank through the bypass valve and directly to the injection port without flowing through the mixer; and a second branch injection line configured to guide formic acid from the storage tank through the bypass valve, through the mixer, and to the injection port.

[0093] In a first aspect of the invention, the electrolysis system may further include: a control system that communicates with a pollution mitigation system and is configured to adjust the concentration of the formic acid solution; and a sensor that maintains fluid communication with the electrolytic cell stack to measure water conductivity data related to water entering the electrolytic cell stack. In a first aspect of the invention, the control system may communicate with the sensor to receive water conductivity data therefrom. In a first aspect of the invention, the control system may be configured to adjust the concentration of the formic acid solution based at least in part on the water conductivity data.

[0094] In a first aspect of the invention, the contamination mitigation system may further include a recirculation line extending between the outlet of the electrolyzer stack and a storage tank, and a three-way valve connected to the recirculation line between the outlet and the storage tank. In the first aspect of the invention, the three-way valve may be configured to guide formic acid from the outlet via the recirculation line to the storage tank when the three-way valve is in a first position, and the three-way valve may be configured to guide formic acid from the outlet to a high-pressure water separator included in the electrolysis system when the three-way valve is in a second position different from the first position.

[0095] In a first aspect of the invention, the electrolysis system may further include: a control system that communicates with a contamination mitigation system and is configured to control the injection of formic acid into the cathode chamber of the electrolyzer stack; and a sensor that maintains fluid communication with the electrolyzer stack to measure water conductivity data related to water entering the electrolyzer stack. In a first aspect of the invention, the control system may communicate with the sensor to receive water conductivity data therefrom. In a first aspect of the invention, the control system may be configured to regulate the injection of formic acid into the cathode chamber based at least in part on the water conductivity data. In a first aspect of the invention, the contamination mitigation system may further include a filter located upstream of a storage tank and configured to filter formic acid. In a first aspect of the invention, the storage tank may include a pressure-reducing valve configured to control pressure buildup resulting from the decomposition of formic acid in the storage tank.

[0096] In a second aspect of the invention, the method may further include: guiding formic acid from a storage tank to the cathode chamber of the electrolytic cell stack prior to the injection step. In a second aspect of the invention, the method may further include: guiding formic acid from the storage tank through the bypass valve and directly into the cathode chamber of the electrolytic cell stack when the bypass valve located between the storage tank and the injection port is in a first position. In a second aspect of the invention, the method may further include: guiding formic acid from the storage tank through the bypass valve and into the mixer when the bypass valve is in a second position different from the first position.

[0097] In a second aspect of the invention, the method may further include: guiding water from a water tank to a mixer, and diluting formic acid with water in the mixer to form a formic acid solution injected into the cathode chamber. In another second aspect of the invention, the method may further include: receiving water conductivity data related to the water entering the electrolyzer stack; and adjusting the concentration of the formic acid solution injected into the cathode chamber of the electrolyzer stack based at least in part on the water conductivity data.

[0098] In a second aspect of the invention, the method may further include: receiving water conductivity data related to water entering the electrolyzer stack; and adjusting the injection of formic acid into the cathode chamber of the electrolyzer stack based at least in part on the water conductivity data. In another second aspect of the invention, the step of injecting formic acid includes manually injecting formic acid into the cathode chamber of the electrolyzer stack via an injection port. In yet another second aspect of the invention, the method may further include guiding the formic acid to the cathode chamber of the electrolyzer stack via a pump.

[0099] Features illustrated or described in connection with an exemplary embodiment may be combined with any other feature or element of any other embodiment described herein. Such modifications and variations are intended to be included within the scope of this disclosure. Furthermore, those skilled in the art will recognize that terms well-known to them may be used interchangeably herein.

[0100] The above description of the embodiments is detailed enough to enable those skilled in the art to practice the claims, and it should be understood that logical, mechanical, and electrical changes can be made without departing from the spirit and scope of the claims. Therefore, the detailed description should not be considered limiting.

[0101] As used herein, elements or steps listed in the singular and beginning with the words "a" or "an" should be understood to not exclude the plural form of the elements or steps unless such exclusion is explicitly stated. Furthermore, references to "an embodiment" of the subject matter herein are not intended to exclude the existence of additional embodiments that also include the listed features. Specifying numerical ranges of units, measurements, and / or values ​​includes, substantially consists of, or comprises all numerical values, units, measurements, and / or ranges and / or endpoints, or ranges within these ranges and / or endpoints, whether or not such numerical values, units, measurements, and / or ranges are expressly specified in this disclosure.

[0102] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” etc., as used herein, do not indicate any order or importance, but are used to distinguish one element from another. The term “or” means including and refers to any or all of the listed items. Furthermore, the terms “connection” and “linkage” are not limited to physical or mechanical connections or linkages, but may also include direct or indirect electrical connections or linkages.

[0103] Furthermore, unless explicitly stated otherwise, embodiments that "comprise," "include," or "have" one or more elements having a particular property may include additional such elements that do not have that property. The terms "comprise" or "include" mean a composition, compound, formulation, or method that includes, but does not exclude, additional elements, components, and / or method steps. The term "comprise" also refers to embodiments of compositions, compounds, formulations, or methods that include, but do not exclude, additional elements, components, or method steps in this disclosure.

[0104] The phrase "consisting of" or "consists of" refers to a mixture, composition, formulation, or method that excludes any additional elements, components, or method steps. The phrase "consisting of" also refers to a compound, composition, formulation, or method that excludes any additional elements, components, or method steps in this disclosure.

[0105] The phrase "consisting essentially of" or "consists essentially of" refers to a composition, compound, formulation, or method that includes additional elements, components, or method steps that do not substantially affect the characteristics of the composition, compound, formulation, or method. The phrase "consisting essentially of" also refers to a composition, compound, formulation, or method disclosed herein that includes additional elements, components, or method steps that do not substantially affect the characteristics of the composition, compound, formulation, or method.

[0106] As used throughout the specification and claims, approximate language may be used to modify any quantitative expression that allows for variation without altering its underlying function. Therefore, values ​​modified by one or more terms (such as “about” and “substantially”) are not limited to specified exact values. In some cases, approximate language may correspond to the precision of the instrument used to measure the value. Scope limitations may be combined and / or interchanged herein and throughout the specification and claims. Unless otherwise specified by context or language, such scopes are identified and include all subscopes contained therein.

[0107] As used herein, the terms “may” and “can” indicate the possibility of occurring in a range of situations; possess a particular attribute, characteristic, or function; and / or qualify one verb by expressing one or more capabilities or possibilities associated with the qualifying verb. Thus, the use of “may” and “can” indicates that the modified term is clearly appropriate, capable, or suitable for the indicated capability, function, or use, while taking into account that in some cases the modified term may sometimes be inappropriate, incapable, or unsuitable.

[0108] It should be understood that the above description is illustrative and not restrictive. For example, the above embodiments (and / or aspects thereof) can be used alone, together, or in combination with each other. Furthermore, many modifications can be made to adapt a particular situation or material to the teachings of the subject matter described herein without departing from its scope. Although the dimensions and types of materials described herein are intended to define parameters of the disclosed subject matter, they are by no means limiting but rather exemplary embodiments. Many other embodiments will become apparent to those skilled in the art upon review of the foregoing description. Therefore, the scope of the subject matter described herein should be determined by reference to the appended claims and the full scope of equivalents to which such claims are entitled.

[0109] This written specification uses examples to disclose several embodiments (including best modes) of the subject matter described herein and to enable those skilled in the art to practice embodiments of the disclosed subject matter, including making and using the apparatus or system and performing methods. The patentable scope of the subject matter described herein is defined by the claims and may include other examples that would occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if their structural elements are not indistinguishable from the literal language of the claims, or if they comprise equivalent structural elements that are not substantially different from the literal language of the claims.

[0110] Although only certain features of the invention have been illustrated and described herein, many modifications and variations will occur to those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all such modifications and variations that fall within the true spirit of the invention.

Claims

1. An electrolysis system, the electrolysis system comprising: An electrolytic cell stack, the electrolytic cell stack including an injection port fluidly connected to the cathode chamber of the electrolytic cell stack, and A contamination mitigation system configured to remove ions from the electrolytic cell stack to mitigate ion contamination in the electrolytic cell stack, the contamination mitigation system comprising: a storage tank containing formic acid; an injection line fluidly connected between the storage tank and the injection port; and a pump connected to the injection line and configured to guide the formic acid from the storage tank to the injection port for injection into the cathode chamber of the electrolytic cell stack.

2. The electrolysis system according to claim 1, wherein, The pollution mitigation system also includes a mixer located downstream of the storage tank and configured to receive the formic acid from the storage tank and water from a water tank contained in the electrolysis system to dilute the formic acid in the mixer and form a formic acid solution.

3. The electrolysis system according to claim 2, wherein, The contamination mitigation system further includes a bypass valve located between the storage tank and the mixer, and wherein the injection line includes: a first branch injection line configured to guide the formic acid from the storage tank through the bypass valve and directly to the injection port without flowing through the mixer; and a second branch injection line configured to guide the formic acid from the storage tank through the bypass valve, through the mixer, and to the injection port.

4. The electrolysis system according to claim 2, further comprising: A control system, which communicates with the pollution mitigation system and is configured to adjust the concentration of the formic acid solution; And a sensor that is in fluid communication with the electrolyzer stack to measure water conductivity data related to the water entering the electrolyzer stack.

5. The electrolysis system according to claim 4, wherein, The control system communicates with the sensor to receive the water conductivity data therefrom, and the control system is configured to adjust the concentration of the formic acid solution based at least in part on the water conductivity data.

6. The electrolysis system according to claim 1, wherein, The pollution mitigation system also includes a recirculation line extending between the outlet of the electrolyzer stack and the storage tank, and a three-way valve connected to the recirculation line between the outlet and the storage tank.

7. The electrolysis system according to claim 6, wherein, The three-way valve is configured to guide the formic acid from the outlet to the storage tank via the recirculation line when the three-way valve is in a first position, and the three-way valve is configured to guide the formic acid from the outlet to a high-pressure water separator included in the electrolysis system when the three-way valve is in a second position different from the first position.

8. The electrolysis system according to claim 1, further comprising: A control system, which communicates with the pollution mitigation system and is configured to control the injection of formic acid into the cathode chamber of the electrolytic cell stack; And a sensor that is in fluid communication with the electrolyzer stack to measure water conductivity data related to the water entering the electrolyzer stack.

9. The electrolysis system according to claim 8, wherein, The control system communicates with the sensor to receive the water conductivity data therefrom, and the control system is configured to adjust the injection of formic acid into the cathode chamber based at least in part on the water conductivity data.

10. The electrolysis system according to claim 1, wherein, The pollution mitigation system also includes a filter located upstream of the storage tank and configured to filter the formic acid.

11. The electrolysis system according to claim 1, wherein, The storage tank includes a pressure relief valve configured to control pressure buildup caused by the decomposition of the formic acid in the storage tank.

12. A method, the method comprising: An electrolytic cell stack is provided, the electrolytic cell stack including an injection port in fluid connection with the cathode chamber of the electrolytic cell stack. Formic acid is injected into the cathode chamber of the electrolytic cell stack via the injection port, and Ions are removed from the electrolytic cell stack via formic acid to alleviate ion contamination in the electrolytic cell stack.

13. The method according to claim 12, further comprising: Prior to the injection step, the formic acid is guided from the storage tank to the cathode chamber of the electrolytic cell stack.

14. The method according to claim 13, further comprising: When the bypass valve located between the storage tank and the injection port is in the first position, the formic acid is guided from the storage tank through the bypass valve and directly into the cathode chamber of the electrolytic cell stack.

15. The method according to claim 14, further comprising: When the bypass valve is in a second position different from the first position, the formic acid is guided from the storage tank through the bypass valve and into the mixer.

16. The method according to claim 15, further comprising: Water is directed from the tank into the mixer, and the formic acid is diluted with the water in the mixer to form a formic acid solution injected into the cathode chamber.

17. The method according to claim 16, further comprising: Receive water conductivity data related to the water entering the electrolyzer stack; And, based at least in part on the water conductivity data, the concentration of the formic acid solution injected into the cathode chamber of the electrolytic cell stack is adjusted.

18. The method according to claim 12, further comprising: Receive water conductivity data related to the water entering the electrolyzer stack; And, based at least in part on the water conductivity data, the injection of formic acid into the cathode chamber of the electrolytic cell stack is adjusted.

19. The method according to claim 12, wherein, The step of injecting formic acid includes manually injecting the formic acid into the cathode chamber of the electrolytic cell stack via the injection port.

20. The method of claim 12, further comprising guiding the formic acid to the cathode chamber of the electrolytic cell stack via a pump.

Images