Hydrogen generation via high fluid velocity electrolysis and gas separation

Abstract

Disclosed are a system and method for the generation of hydrogen from a source of liquid comprising water. The system comprises a high fluid velocity electrolyzer comprising an inlet and an outlet, the inlet of the high fluid velocity electrolyzer fluidly connected to the source of liquid, and a gas fractionation system fluidly connected to the outlet of the high fluid velocity electrolyzer.

Description

[0001] HYDROGEN GENERATION VIA HIGH FLUID VELOCITY ELECTROLYSIS

[0002] AND GAS SEPARATION

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] The present application claims priority to U.S. Provisional Application No. 63 / 471,063, filed June 5, 2023 and titled “Hydrogen Generation Via High Fluid Velocity Electrolysis and Gas Separation”, the content of which is incorporated herein in its entirety.

[0005] BACKGROUND

[0006] 1. Field of Invention

[0007] Aspects and embodiments disclosed herein are generally directed to the generation of hydrogen by electrolysis of water.

[0008] 2. Discussion of Related Art

[0009] Energy demand across the world continues to increase. Combustion of fossil fuels currently supplies approximately 80% of the world’s energy, producing large quantities of carbon dioxide as a combustion byproduct. At the same time there is a recognized desire to reduce carbon dioxide emissions in an effort to mitigate the effects of atmospheric carbon dioxide buildup on global warming. Accordingly, there is an increasing desire to develop and deploy energy generation systems and technologies that do not rely on the combustion of fossil fuels.

[0010] An alternative fuel to fossil fuels such as oil, coal, and natural gas is hydrogen. The combustion of hydrogen produces water vapor and no carbon dioxide and is thus considered a “clean” or “green” fuel. Hydrogen may be generated by the electrolysis of water in which water molecules are split into hydrogen and oxygen by the application of an electric current.

[0011] The generation of hydrogen by electrolysis of water is often performed utilizing high purity water with somewhat complex apparatus including ion selective membranes separating anode and cathode compartments of an electrolyzer. The vast majority of the water on the planet, however, is in the form of seawater having high levels of dissolved solids such as chloride, sodium, sulfate, magnesium, calcium, and potassium. It would be desirable to develop and implement simple and reliable systems and processes for generation of hydrogen from seawater.

[0012] SUMMARY

[0013] In accordance with an aspect of the present invention, there is provided a system for the generation of hydrogen from a source of liquid comprising water. The system comprises a high fluid velocity electrolyzer comprising an inlet and an outlet, the inlet of the high fluid velocity electrolyzer fluidly connected to the source of liquid, and a gas fractionation system fluidly connected to the outlet of the high fluid velocity electrolyzer.

[0014] BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in even' drawing. In the drawings:

[0016] FIG. 1 is a diagram of one example of a system for generating hydrogen from sweater via electrolysis that includes a plurality of pretreatment steps prior to the electrolysis step;

[0017] FIG. 2 illustrates an example of a concentric tube electrode electrolyzer that may be utilized in accordance with various aspects and embodiments disclosed herein;

[0018] FIG. 3 is a table illustrating the amount of hydrogen generated in the different electrolyzers in a series arrangement of 20 concentric tube electrode electrolyzers;

[0019] FIG. 4 illustrates steps in a process for gas fractionation by cry ogenic gas separation;

[0020] FIG. 5 is a schematic of a system for generating hydrogen from seawater;

[0021] FIG. 6 is a schematic diagram of a control system that may be utilized in the system of FIG. 5; and

[0022] FIG. 7 is a schematic illustration of a memory structure for the control system of FIG. 6. DETAILED DESCRIPTION

[0023] Aspects and embodiments disclosed herein are not limited to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. Aspects and embodiments disclosed herein are capable of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including.” “comprising,” “having,” “containing.” “involving,” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

[0024] Electrolysis is a promising option for carbon-free hydrogen production from renewable and nuclear resources. Electrolysis is the process of using electricity to split water into hydrogen and oxygen. This reaction takes place in a unit called an electrolyzer. Electrolyzers can range in size from small, appliance-size equipment that is well-suited for small-scale distributed hydrogen production to large-scale, central production facilities that could be tied directly to renewable or other nongreenhouse-gas-emitting forms of electricity production.

[0025] Electrolysis is a leading hydrogen production pathway to achieve the goal of reducing the cost of clean hydrogen by 80% to $1 per 1 kilogram in 1 decade ("1 1 1"). Hydrogen produced via electrolysis can result in zero greenhouse gas emissions, depending on the source of the electricity used. The source of electricity — including its cost and efficiency, as well as emissions resulting from electricity generation — should be considered when evaluating the benefits and economic vi abi 1 i ty of hydrogen production via electrolysis. In many regions of the United States, today’s power grid is not ideal for providing electricity for electrolysis because of the greenhouse gases released and the amount of fuel utilized due to the low efficiency of the electricity generation process. Hydrogen production via electrolysis is being pursued for renewable (wind, solar, hydro, geothermal) and nuclear energy options. These hydrogen production pathways result in virtually zero greenhouse gas and criteria pollutant emissions; however, the production cost should be decreased significantly to be competitive with more mature carbon-based pathways such as natural gas reforming. As of 2020, the global green hydrogen market was estimated at $1. 14BN and is projected to grow to S15.1BN by 2026 (Grand View Research, 2020; Research and Markets, 2021).

[0026] Current state of the art for electrolytic hydrogen generation involves the use of membrane separated electrolyzers. Such devices, while efficient for hydrogen generation, are very sensitive to the influent water quality, and require high levels of influent total dissolved solids (TDS). total suspended solids (TSS), and organics removal to enable long term operation. In terms of benefits, membrane separated electrolytic hydrogen generators separate the gaseous oxygen and hydrogen that is generated, simplifying downstream gas processing.

[0027] One or more aspects disclosed herein relate to systems and methods for generating hydrogen by the electrolysis of water. According to some embodiments, the water may be brackish water or seawater. Gasses such as oxygen or chlorine that are co-generated along with hydrogen during the electrolysis of water may be separated from the hydrogen to provide a substantially pure hydrogen product. The gas separation process may include utilization of a cryogenic gas separation system.

[0028] One example of a system for generating hydrogen from seawater is illustrated in FIG. 1. Seawater, which may have a TDS level of 35,000 ppm or more, a TSS level of 10 NTU or above, and an organic compound concentration of 5 ppm or more is used as the source of hydrogen. The seawater undergoes several pretreatment steps prior to electrolysis. A first pretreatment step is a solids removal step 10 in which a screen, sand filter, or other coarse filter is used to remove most of the suspended solids from the influent seawater. A second pretreatment step is an organics removal step 20 to remove most of the organic contaminants. Organics removal may be performed by, for example, biological treatment in accordance with various systems and methods known in the art. A series of TDS removal steps 30A, 30B, 30N follow in which the partially pretreated seawater may be passed through membrane filtration apparatus such as nanofiltration, ultrafiltration, and / or reverse osmosis apparatus to reduce the TDS level of the partially pretreated seawater. The pretreated seawater, having significantly reduced levels of TDS, TSS, and organics, then undergoes electrolysis to form hydrogen and byproducts such as oxygen. The hydrogen and oxygen may be generated in separate compartments of the electrolyzer from which the gasses are separately withdrawn.

[0029] An apparatus and method such as illustrated in FIG. 1 may be undesirably costly in terms of both capital and operational costs and more complex than may be desired due to the multiple pretreatment operations.

[0030] In the electrolysis of water, hydrogen is generated at the cathode of an electrolyzer in accordance with the electrochemical reaction:

[0031] Oxygen is generated at the anode of the electrolyzer in accordance with the electrochemical reaction:

[0032] If there is chloride in the water undergoing electrolysis, the oxygen generation reaction may compete with a chlorine generation reaction:

[0033] Hydrogen generation may also be accompanied by the production of NaOCl in an electrolyzer supplied with an aqueous solution including NaCl in accordance with the following reactions:

[0034] Reaction at anode: 2C1’ - Cl2+ 2e’ (E°ox= -1.358 V)

[0035] Reaction at cathode: 2H2O + 2e’ - H2+ 2OH’ (E°red = -0.8277 V)

[0036] Overall reaction:

[0037] In these reactions, electrical potentials listed are under conditions of IM concentration (activity) of the reactants and products as well as standard condition (25 °C and 1 atm.)

[0038] Voltage across the anode and the cathode can be measured to determine when hydrogen gas begins to generate in an electrolyzer. Parameters such as temperature, pH, and composition of the feed into an electrolyzer may affect the voltage at which hydrogen gas begins to be generated. Pressure, flow rate, and turbulence may also have an effect on the voltage at which hydrogen gas begins to be generated. In some embodiments a power supply may be controlled to provide a voltage across the anode and cathode of an electrolyzer sufficient to cause hydrogen to be generated. This voltage may be, for example, above about 1.0V, 1.1V, 1.2V, 1.3V, 1.4V, 1.5V, 2.0V, 3.0V, or 4.0V, although as noted above, factors such as feed solution pH, composition, and / or pressure may change the voltage at which hydrogen begins to be generated in the electrolyzer.

[0039] Composition of the solution within an electrolyzer may be altered by altering flow rate or velocity of the feed stream. Generally, increasing flow rate or velocitymay increase turbulence and mixing of the solution within the system. Since reactions typically occur locally at the anode or cathode of the electrolyzer, increasing turbulence may have an effect on normalizing solution composition and pH within the electrolyzer.

[0040] Feedback or feedforw ard control of flow rate or velocity may be implemented. In some embodiments, flow rate or flow velocity of the feed is measured with a flow meter. One or more parameters of a system including one or more electrolyzers may be adjusted responsive to the flow rate or velocity measurement. For example, flow rate or velocity. pH, or temperature can be adjusted responsive to the measurement. The measurement may be communicated to a circulation pump to control flow rate or velocity as necessary. Flow rate may be controlled to be between about 0.1-10 m3 / hr. Flow rate may be controlled to be 0. 1 m3 / hr, 0.5 m3 / hr, 1.0 m3 / hr, 2.0 m3 / hr, 3.0 m3 / hr, 4.0 m3 / hr, 5.0 m3 / hr, 6.0 m3 / hr, 7.0 m3 / hr, 8.0 m3 / hr, 9.0 m3 / hr, 9.5 m3 / hr, or 10 m3 / hr.

[0041] Flow velocity may be controlled between about 1.0 m / s and 4.0 m / s. Flow velocity may be controlled to be about 1.0 m / s, 2.0 m / s, 3.0 m / s. or 4.0 m / s. In some embodiments, flow velocity can be controlled to between about 2.0 and 2.5 m / s. Flow velocity can be controlled to between about 2.5 m / s and 3.0 m / s. Flow velocity can be controlled to be between about 3.0 m / s and 3.5 m / s. In some embodiments, flowvelocity can be controlled to be about 2.0 m / s, 2. 1 m / s, 2.2 m / s, 2.3 m / s, 2.4 m / s, 2.5 m / s, 2.6 m / s, 2.7 m / s, 2.8 m / s, 2.9 m / s, 3.0 m / s, 3.1 m / s, 3.2 m / s, 3.3 m / s, 3.4 m / s, or 3.5 m / s. Flow rate or velocity may be increased or decreased as desired to increase or decrease turbulence and mixing. For example, a concentric tube electrode electrolysis cell may be employed in marine and offshore applications with seawater as feed. The liquid velocity through the cell can be about 2. 1 m / s. resulting in highly turbulent flow which may reduce the potential for fouling and scaling on the electrode surfaces. Additionally, one or more parameters of the aqueous solution entering, leaving, or within the system may be measured to determine a desired adjustment of flow rate or flow velocity. For example, flow rate or velocity may be increased or decreased based on a measurement of local pH within the system or composition of the aqueous solution entering, leaving, or within the system. Flow rate or velocity7may be increased where local pH within the system varies widely to neutralize pH, or where a measurement of properties of aqueous solution exiting the system (the ■‘product stream”) indicates that there may be scaling of the electrodes.

[0042] In some embodiments, oxidation reduction potential (ORP) of the feed, of aqueous solution within the system, or of the product stream can be measured with a sensor. Any one or more parameters of the system may be adjusted responsive to the ORP measurement. For example, flow rate, pH. temperature, or feed composition can be adjusted responsive to the ORP measurement.

[0043] Variations in TDS of the feed stream may affect its conductivity7. Electrolytic cell voltage and conductivity are inversely related. Thus, in some embodiments, overall power consumption of an electrolytic cell can be controlled by controlling TDS concentration in the feed stream. Feed stream TDS concentration may be controlled by7selectively introducing either seawater, brackish water, brine, freshw ater, or a combination thereof into or as the feed stream. Conductivity of the feed stream or product stream may be measured with a sensor. Any one or more parameters of the system may be adjusted responsive to the conductivity measurement. In some embodiments, flow rate, feed composition, or pH may be adjusted responsive to the conductivity7measurement.

[0044] Electrolyzers that may be utilized for the electrolysis of water to produce hydrogen in accordance with aspects and embodiments disclosed herein may include plate and frame type electrolyzers or concentric tube electrode (CTE) electrolyzers, an example of which is illustrated in various view s in FIG. 2 and embodiments of w hich are described in PCT application PCT / US2016 / 018210, published as WO 2016 / 133983. that is incorporated herein by reference in its entirety for all purposes. Examples of suitable CTE electrolyzers are available from Electrocatalytic Ltd. The term “tube” as used herein includes cylindrical conduits, however, does not exclude conduits having other cross-sectional geometries, for example, conduits having square, rectangular, oval, or obround geometries or cross-sectional geometries shaped as any regular or irregular polygon.

[0045] The terms “concentric tubes” as used herein includes tubes sharing a common central axis but does not exclude tubes surrounding a common axis that is not necessarily central to each of the concentric tubes in a set of concentric tubes or tubes having axes offset from one another.

[0046] Aspects and embodiments disclosed herein are not limited to the number of electrodes, the space between electrodes, the electrode material, material of any spacers between electrodes, number of passes within the electrolyzers, or electrode coating material.

[0047] Conventionally, it was found desirable to limit or prevent the generation of hydrogen in a CTE electrolyzer. Diffusion of hydrogen into material such as titanium from which electrodes in CTE electrolyzers are often formed may lead to embrittlement of the electrodes and increase the potential for mechanical failure of the electrodes. Further, hydrogen gas bubbles may blind portions of the electrodes, leaving less electrode area to perform the desired electrochemical reactions in the electrolyzer. Accordingly, several methods for reducing or eliminating hydrogen generation in a CTE electrolyzers have been developed. For example, PCT Application Publication No. WO 2017 / 049052, incorporated herein by reference, describes the addition of oxygen or another oxidant into a feed stream of an CTE electrolyzer to react with any hydrogen that is generated during operation and form water, hydroxide, or other species that are preferable to hydrogen.

[0048] At a flow velocity of 2-3 m / s, CTE electrolyzers as disclosed in PCT / US2016 / 018210 are capable of self-cleaning operation, assuming a feed stream with Na+concentrations between about 10,000 and 16,000 ppm, Cl" concentrations between about 18,000 and 23,000 ppm, Mg2+concentrations between about 750 and 1,800 ppm, and Ca2+concentrations between about 200 and 500 ppm.

[0049] Simulated hydrogen generation rates for examples of CTE electrolyzers are shown in the simulation results presented in FIG. 3. The table of FIG. 3 assumes 20 CTE electrolyzer cells connected in series with seawater flowing through the system at 24 m3 / hr. Each electrolyzer generates 0.495 m3 / hr of hydrogen with the second column of the table of FIG. 3 indicating the cumulative amount of hydrogen generated. Pressure at the inlet of the first electrolyzer was simulated as 20 ban which decreased for each subsequent electrolyzer. The fourth column of the table “Dissolvable Hydrogen m3 / hr” indicates the total volume of hydrogen that is dissolvable in the seawater at the pressure at each electrolyzer and the fifth column “Hydrogen in Cell m3 / hr” represents the total amount of dissolved hydrogen (negative numbers) or if the seawater is saturated in hydrogen (positive numbers). The seawater becomes saturated with hydrogen after the 10th electrolyzer. The third column “Hydrogen Volume @ Line Pressure m3 / hr” indicates the amount of hydrogen existing in gaseous form in each electrolyzer and is the sum of the values in the fourth and fifth column for each electrolyzer.

[0050] As the term is used herein, an “electrolyzer” may refer to a single electrolyzer cell, such as the electrolyzer cell illustrated in FIG. 2, or to multiple electrolyzer cells connected in series and / or parallel.

[0051] High velocity fluid flow through a CTE electrolyzer may mitigate cathodic scale formation in matrices with high concentrations of divalent cations. This phenomenon is largely due to local pH reduction, enhanced mass transfer, and mechanical electrode scouring. CTE electrolyzers, while efficient for the generation of oxygen and hydrogen, generally do not separate the two gasses, as they do not have discrete compartments, which limits their efficacy for downstream hydrogen extraction. To use a non-separated high fluid velocity electrolyzer (HFVE) for hydrogen generation, downstream gas separation is therefore desirable.

[0052] Cryogenic gas separation is an example of a process that may be utilized for the fractionation of various gasses. In some embodiments, such processes involve compression, cooling, and purification to separate and the constituent gasses, refining them into discrete streams. A high level schematic example of an embodiment of a cryogenic gas fractionation process is shown in FIG. 4. Cryogenic gas fractionation systems capable of separating hydrogen from other gasses (for example, oxygen and chlorine) produced by the electrolysis of water, including brackish water or seawater, are commercially available from companies such as Clean Power Hydrogen Group Limited (Doncaster, UK), e.g., the model MFE220 membrane free electrolyzer, or Air Products and Chemicals, Inc. (Allentown, PA), various models.

[0053] By combining a high fluid velocity, non-separated hydrogen electrolyzer (e.g., a CTE electrolyzer) with a downstream gas fractionation system, it is possible to overcome the current limitation of such electrolyzers. A non-limiting example embodiment of a system including a high fluid velocity, non-separated hydrogen electrolyzer and a downstream gas fractionation system is shown in FIG. 5. Such an embodiment represents a significant improvement versus current state of art membrane separated electrolyzer systems, such as that illustrated in FIG. 1.

[0054] As shown in FIG. 5, an electrolytic hydrogen generation system 100 as disclosed herein may include at least a high fluid velocity electrolyzer, for example, a CTE electrolyzer, for the generation of hydrogen and a downstream gas fractionation system for the separation of hydrogen and oxygen (and / or other gasses).

[0055] Various pumps (e.g., pumps Pl and P2 and additional pumps not illustrated) may be included in one or more portions of the system 100 to cause flow of the various aqueous solutions involved. Various sensors S that may measure various operating parameters within one or more portion of the system and the various aqueous solutions involved may also be present. The one or more sensors S may monitor one or more parameters of fluid flowing through the system, for example, of an aqueous solution to be introduced to an electrolyzer, fluid internal to the electrolyzer, or of product solution produced by or generated in the electrolyzer. These parameters may include, for example, flow rate, ionic concentration, chlorine concentration, oxygen concentration, hydrogen concentration, pH, electrical parameters, temperature, oxygen reduction potential (ORP). or any other parameters of interest. Additional sensors may monitor parameters of the electrolyzer itself, for example, current and / or voltage across an anode-cathode pair in the electrolyzer or temperature of or within the electrolyzer.

[0056] The pumps and sensors may be in communication with a control system or controller 150 which communicates with the sensors and pumps and controls operation of the pumps and other elements of the system to achieve desired operating parameters. Various operating parameters of the electrolyzers disclosed herein may be controlled or adjusted by the control system or controller based on various parameters measured by various sensors located in different portions of the electrochemical systems. The controller may be further configured to regulate the concentration of the product compound generated in the electrolyzer based at least on an oxidation-reduction potential of liquid in a point of use fluidly connectable to or connected to the outlet of the housing of the electrolyzer.

[0057] The controller may be programmed or configured to regulate introduction of the aqueous solution into the electrolyzer based at least on one or more of temperature in the electrolyzer, pH of the aqueous solution, pH of a product solution generated in the electrolyzer, flow rate of the aqueous or product solution, ORP of the aqueous or product solution, or current or voltage applied across the anode and the cathode.

[0058] The controller may be programmed or configured to regulate a current across the anode-cathode pair of the electrolyzer based on a flow rate of the aqueous solution.

[0059] The controller may be configured to change, alter, or regulate the current applied by the electrodes. The controller may regulate a voltage applied across the anode and the cathode. The controller may be programmed or configured to regulate the applied current or applied voltage responsive to a flowrate of the aqueous solution into the electrolyzer, a voltage measured across the anode and the cathode, or hydrogen gas concentration in the aqueous solution proximate the cathode. The controller may be programmed or configured to regulate the applied current, applied voltage, or polarity of the electrodes responsive to a flow rate, a pH measurement, a temperature measurement, or an oxidation-reduction potential of at least one process solution. The controller may be programmed or configured to regulate the applied current, applied voltage, polarity of the electrodes, or pulsed waveform responsive to a dissolved oxygen concentration or dissolved hydrogen concentration of at least one process solution.

[0060] The controller may be programmed or configured to regulate the applied current, applied voltage, or polarity' of the electrodes sufficient to facilitate generation of hydrogen gas within the electrochemical cell. The applied current, applied voltage, or polarity of the electrodes may be dependent on, for example, flow conditions or turbulence within the electrolyzer, diffusivity of oxygen or hydrogen within the electrolyzer, operating current, cathode area. etc.

[0061] In some embodiments, the controller may be programmed or configured to regulate one or more conditions of the aqueous solution in an amount sufficient to enhance generation of hydrogen gas within the electrolyzer. The controller may be programmed or configured to regulate a flow rate or composition of the aqueous solution. The regulation of the flow rate or composition of the aqueous solution may be dependent on, for example, flow conditions or turbulence within the electrolyzer, diffusivity' of oxygen or hydrogen within the electrolyzer, operating current, cathode area, etc. The composition of the aqueous solution may be regulated by dosing with one or more compounds, for example, a pH adjustment or balancing agent.

[0062] In general, the controller may be programed to make any change to initiate or maintain generation of hydrogen gas. In an IV-curve. a change in voltage may indicate generation of hydrogen gas. Thus, the controller may be enabled to control conditions that maintain the voltage indicative of hydrogen gas production (or predetermined threshold voltage) above a limit that may indicate generation of hydrogen gas. Because hydrogen gas generation is generally dependent on conditions such as temperature, pH, ORP, dissolved oxygen concentration, and dissolved hydrogen concentration, any one or more of these parameters may be controlled to be maintained within a predetermined range that indicates production of hydrogen gas within the system.

[0063] The controller for monitoring and controlling operation of the various elements of system may include a computerized control system. The output devices configured to act in response to instructions from the controller may comprise valves, pumps, or switches which may be utilized to introduce aqueous solution (for example, brine, brackish water, or seawater) from the source into the electrolyzer system and / or to control the speed of pumps. One or more sensors may also provide input to the controller. These sensors may include, for example, sensors which may be. for example, pressure sensors, chemical concentration sensors, temperature sensors, or sensors for any other parameters of interest to system. These sensors may be located in any portion of the system where they would be useful, for example, upstream of point of use in fluid communication with a product solution, within the electrolyzer or in fluid communication with a solution proximate the anode or the cathode, and / or upstream of an inlet of the electrolyzer in fluid communication with the source of aqueous solution. In addition, the controller may contain one or more interfaces (not shown) that connect the controller to a communication network in addition or as an alternative to the disclosed interconnection mechanisms.

[0064] The system of FIG. 5 may include a pH adjustment system including a source of pH adjuster, for example, a mineral acid or a caustic such as NaOH and a heat exchanger (omitted from FIG. 5 for clarity). The pH adjustment system may adjust the pH of the aqueous solution to a pH rendering reactions for generation of a desired species of product in the electrolyzer favorable, for example, to a pH low enough such that the formation of hydrogen gas in the electrolyzer is enhanced. The pH adjustment system may adjust the pH of the aqueous solution to a pH of, for example, between about 2 and about 14 or between about 7 and about 10. The heat exchanger may be used to adjust the temperature of the aqueous solution to a temperature that results in desired reaction kinetics in the electrochemical cell and / or to adjust the solubility of oxygen or hydrogen in the aqueous solution.

[0065] A dissolved oxygen sensor may be used to measure dissolved oxygen levels in the aqueous solution. A dissolved hydrogen sensor may be used to measure dissolved hydrogen levels in the aqueous solution. A dissolved oxygen or hydrogen sensor may measure oxygen or hydrogen at an electrode of the system or in the product solution.

[0066] A flow sensor may provide product solution flow rate data to the controller which may use this data to control operation of a pump for the influent aqueous solution and / or current or voltage applied across the anode-cathode pair of the electrolyzer. In some embodiments, a flow sensor may provide aqueous solution flow rate data to the controller.

[0067] An electrical meter, for example, a potentiostat may be utilized to measure electrical parameters and / or generate a current- voltage curve of the aqueous solution or product solution, which may be utilized to gain information about whether the electrolyzer is operating in a desired range. In some embodiments, the desired range is one in which hydrogen gas is generated within the electrolyzer. Data from the electrical meter may be used by the controller to control operation of one or more pumps (i.e.. a rate of introduction of the aqueous solution into the electrolyzer) and / or current or voltage applied across the anode-cathode pair of the electrolyzer.

[0068] An oxidation reduction potential (ORP) meter may be provided to obtain readings of ORP of liquid in the point of use which may be used by the controller to determine when and how much product solution be dosed into the point of use. In some embodiments, an oxidation reduction potential (ORP) meter may be provided to obtain readings of ORP of the product solution which may be used by the controller to regulate a rate of introduction of the aqueous solution into the electrolyzer.

[0069] The system may further include a gas separation column that may be used to remove dissolved hydrogen, oxygen, or other gasses from the product solution and supply these gasses to the gas fractionation apparatus. The gas separation column may be included in for example, the high velocity H2 generator 130 or the gas fractionation system 140 in the system 100 of FIG. 5.

[0070] Various components of the system may be serially repeated in line with one another. For example, the system may have multiple repeated subsystems including a heat exchanger, pH adjustment system, electrolyzer, and possibly pump P arranged serially in line with one another.

[0071] The feed stream to an electrolytic hydrogen generation system as disclosed herein may include seawater having TDS, TSS, and organic contaminant concentrations similar to those shown in FIGS. 1 and 5, brine, brackish water, ground water, freshwater, or potable water.

[0072] Seawater generally has a salinity of between about 3.0% and 4.0%, for example, seawater may have a salinity of about 3.5%, 3.6%. or 3.7%. Seawater comprises dissolved ions including sodium, chloride, magnesium, sulfate, and calcium. Seawater may further include one or more of sulfur, potassium, bromide, carbon, and vanadium. Seawater may have a total dissolved solids (TDS) content of about 35,000 mg / 1. Brine generally has a salinity of greater than about 3.5%. For example, brine may have a salinity of about 4.0%. 4.5%, 5.0%, 7.5%. or about 10%. Brine may have a TDS content of greater than about 35,000 mg / 1. Saturated brine may have a salinity' of up to about 25.0%. Brackish water generally has a salinity' of less than 3.5%. Brackish water may have a salinity of about 3.0%, 2.5%, 2.0%. or 1.0%. Brackish water may have a TDS content of less than about 35,000 mg / 1. For example, brackish water may have a TDS content between about 1,000 mg / 1 to about 10,000 mg / 1. Potable water may have a TDS content of 500 ppm or less.

[0073] The concentration of different dissolved solids in seawater may vary depending on location, however, one example of seawater may include the following components: Table 1: Typical seawater components and concentrations

[0074]

[0075] The different ionic components of seawater from different locations are indicated in Table 2 below: Table 2: Major Ion Composition of Seawater (mg / L)

[0076] In general, the conductivity of the feed stream may be between about 0 and 25 S / cm, as dependent on the salinity. Brackish water having a salinity between about 0.5% and 2.0% may have a conductivity of between about 0.5 S / cm and about 4.0 S / cm. for example, about 0.8 S / cm or about and 3.0 S / cm. Seawater having a salinity of about 3.5% may have a conductivity' of between about 4.5 S / cm and 5.5 S / cm, for example, about 5.0 S / cm or about 4.8 S / cm. Brine having a salinity between about 5.0% and 10% may have a conductivity of between about 7 S / cm and 13.0 S / cm, for example, about 12.6 S / cm. Saturated brine having a salinity of about 25% may have a conductivity of between about 20.0 S / cm and about 23.0 S / cm, for example, about 22.2 S / cm. In general, salinity and conductivity may follow the linear relationship of y = 0.9132x + 1.6332, where y is conductivity (S / cm) and x is percent salinity (%NaCl).

[0077] Electrolytic cells and devices as disclosed herein may be included as part of a larger system. In some embodiments, the system is a sea-based system, for example, a ship or an oil rig, and in other embodiments is a land based building, for example, a power plant, an oil drilling facility or system or other industrial facility. In other embodiments, the system is or may include a swimming pool, or a treatment system for drinking water, wastewater, or industrial water treatment processes, that uses one or more products of an electrolyzer in the system, for example, a disinfectant to treat or disinfect water.

[0078] Such a system may draw process liquid or electrolyte, which in some embodiments is seawater, brackish water, or brine, from sources external and / or internal to the system. For example, if the system is a sea-based system, an external source may be the ocean and an internal source may be, for example, a ballast tank in a ship. In land based system, an external source may be the ocean and an internal source may be brackish wastewater from an industrial process performed in the system. The one or more electrolyzers may produce product solution, for example, chlorinated water and / or a solution including sodium hypochlorite from the aqueous solution and distribute it to a point of use. The point of use may be a source of cooling water for the system, a source of disinfection agent for a ballast tank of a ship, a downhole of an oil drilling system, or any other system in which a chlorine-based disinfection solution may be useful.

[0079] Referring back to FIG. 5, the hydrogen generation system 100 receives an aqueous feed solution, for example, seawater, brackish water, fresh or potable water, or combinations thereof at an inlet 110. FIG. 5 indicates parameters of the influent aqueous solution that are consistent with seawater, but the system 100 is not limited to using seawater as a source of hydrogen. The influent aqueous solution may be pretreated in a solids removal apparatus 120. for example, a coarse screen, hydrocyclone, settling basin, or other form of solids removal apparatus to remove suspended solids, for example, suspended solids having characteristic dimensions (e.g., length or width) greater than 1pm, greater than 5pm, greater than 25pm, or any other dimension desired for a particular implementation. The pretreated aqueous solution, having a reduced TSS concentration as compared to the influent aqueous solution, is introduced into a high velocity hydrogen generator 130, also referred to herein as a high fluid velocity' electrolyzer. The high velocity hydrogen generator 130 may be or may include one or more electrolyzer cells, for example, CTE electrolyzers as described above. The one or more electrolyzer cells may be connected fluidically in series or in parallel and may be considered ‘’high velocity” because aqueous solution is pumped by a fluid pump Pl through the one or more electrolyzer cells at a velocity sufficient to render the one or more electrolyzer cells self-cleaning, e.g., at a velocity sufficient to prevent the formation of scale of the electrodes of the one or more electrolyzer cells. This velocity may be, for example, 2 m / s or more. Hydrogen and other gasses, for example, oxygen or chlorine are removed from an outlet of the high velocity hydrogen generator 130, for example, by a gas pump P2 and introduced into a gas fractionation system 140. The gas fractionation system 140 may be a cryogenic gas fractionation system. The gas fractionation system 140 separates the gasses from the high velocity' hydrogen generator 130 into a primary hydrogen product which is captured for use in energy7generation and into other gas products, for example, oxygen that may be captured or released to the environment. The aqueous solution exiting the high velocity hydrogen generator 130 may include useful products, for example, hypochlorite that may be sent to a point of use, optionally after further treatment to remove any undesired components.

[0080] It should be noted that in the system 100 of FIG. 5, in contrast to that of FIG. 1, there is no requirement for the removal or reduction of organic contaminants or dissolved solids between the solids removal operation (solids removal apparatus 110) and the electrolysis operation (high velocity hydrogen generator 130). The system 100 may thus be provided without membrane filtration apparatus disposed between the source of aqueous liquid and the inlet of the high fluid velocity electroly zer and / or without a biological reactor disposed between the source of aqueous liquid and the inlet of the high fluid velocity electrolyzer.

[0081] One or more sensors S may be provided at various locations in the system 100 and may be configured to measure one or more parameters, for example, temperature, flow rate, contaminant concentration, pH, oxidation-reduction potential (ORP), total organic carbon (TOC), dissolved oxygen and / or hydrogen concentration, hydrogen peroxide concentration, purity, etc. of any of the aqueous solutions in different portions of the system 100 and / or of the gasses generated by the high velocity hydrogen generator 130 and / or operating parameters of any of the unit operations of the system, for example, operating parameters of the high velocity hydrogen generator 130. A controller 150 of the system, described further below, may receive readings from the one or more sensors S and adjust one or more operating parameters of the system to obtain a desired level of a parameter or parameters read by the one or more sensors S. Signal and control lines are not illustrated in FIG. 5 for the sake of clarity. The operating parameters of the system may include, for example, power (current or voltage or both) applied to the high velocity hydrogen generator 130, flow rate of the aqueous solution, or any other operating parameter of the system.

[0082] Various additional pumps or valves may be included in the system described above to control flow of the various aqueous solutions involved but are not illustrated for the purpose of clarity. In one or more embodiments, any of which may be relevant to one or more aspects, the systems and techniques disclosed herein may utilize one or more subsystems that adjusts or regulates or at least facilitates adjusting or regulating at least one operating parameter, state, or condition of at least one unit operation or component of the system or one or more characteristics or physical properties of a process stream. To facilitate such adjustment and regulator}' features, one or more embodiments may utilize controllers and indicative apparatus that provide a status, state, or condition of one or more components or processes. For example, at least one sensor may be utilized to provide a representation of an intensive property or an extensive property of, for example, the influent aqueous solution of pretreated aqueous solution. Thus, in accordance with a particularly advantageous embodiment, the systems and techniques may involve one or more sensors or other indicative apparatus, such as composition analyzers, or conductivity cells, that provide, for example, a representation of a state, condition, characteristic, or quality of the aqueous solution entering or leaving any of the unit operations of the system.

[0083] Various operating parameters of the electrochlorination systems disclosed herein may be controlled or adjusted by an associated control system or controller based on various parameters measured by various sensors located in different portions of the systems. The controller may be programmed or configured to regulate one or more of a current across the anode-cathode pair or a voltage applied across the anodecathode pair of an electrolyzer for the production of H2 based on a flow rate or composition of the influent aqueous solution.

[0084] The controller used for monitoring and controlling operation of the various elements of systems disclosed herein may include a computerized control system. Various aspects of the controller may be implemented as specialized software executing in a general-purpose computer system 200 such as that shown in FIG. 6. The computer system 200 may include a processor 202 connected to one or more memory devices 204, such as a disk drive, solid state memory, or other device for storing data. Memory 204 is typically used for storing programs and data during operation of the computer system 200. Components of computer system 200 may be coupled by an interconnection mechanism 206, which may include one or more busses (e.g., between components that are integrated within a same machine) and / or a network (e.g., between components that reside on separate discrete machines). The interconnection mechanism 206 enables communications (e.g., data, instructions) to be exchanged between system components of system 200. Computer system 200 also includes one or more input devices 208, for example, a keyboard, mouse, trackball, microphone, touch screen, sensors S and one or more output devices 210, for example, a printing device, display screen, and / or speaker, one of pumps Pl or P2 or a power supply 160 to the high velocity hydrogen generator 130.

[0085] The output devices 210 may also comprise valves, pumps, or switches which may be utilized to control the speed of pumps or the state (open or closed) of valves of systems as disclosed herein. One or more sensors 214 may also provide input to the computer system 200. These sensors may include, for example, sensors S, which may be, for example, pressure sensors, chemical concentration sensors, temperature sensors, or sensors for any other parameters of interest to the systems disclosed herein. These sensors may be located in any portion of the system where they would be useful. In addition, computer system 200 may contain one or more interfaces (not shown) that connect computer system 200 to a communication network in addition or as an alternative to the interconnection mechanism 206.

[0086] The storage system 212, shown in greater detail in FIG. 7, typically includes a computer readable and writeable nonvolatile recording medium 302 in which signals are stored that define a program to be executed by the processor 202 or information to be processed by the program. The medium may include, for example, a disk or flash memory. Typically, in operation, the processor causes data to be read from the nonvolatile recording medium 302 into another memory 304 that allows for faster access to the information by the processor than does the medium 302. This memory 304 is typically a volatile, random access memory such as a dynamic random access memory (DRAM) or static memory (SRAM). It may be located in storage system 212, as shown, or in memory system 204. The processor 202 generally manipulates the data within the integrated circuit memory’ 304 and then copies the data to the medium 302 after processing is completed. A variety of mechanisms are known for managing data movement between the medium 302 and the integrated circuit memory element 304, and aspects and embodiments disclosed herein are not limited thereto. Aspects and embodiments disclosed herein are not limited to a particular memory system 204 or storage system 212.

[0087] The computer system may include specially-programmed, special-purpose hardware, for example, an application-specific integrated circuit (ASIC). Aspects and embodiments disclosed herein may be implemented in software, hardware or firmware, or any combination thereof. Further, such methods, acts, systems, system elements and components thereof may be implemented as part of the computer system described above or as an independent component.

[0088] Although computer system 200 is shown by way of example as one type of computer system upon which various aspects and embodiments disclosed herein may be practiced, it should be appreciated that aspects and embodiments disclosed herein are not limited to being implemented on the computer system as shown in FIG. 20. Various aspects and embodiments disclosed herein may be practiced on one or more computers having a different architecture or components than shown in FIG. 6.

[0089] Computer system 200 may be a general-purpose computer system that is programmable using a high-level computer programming language. Computer system 200 may be also implemented using specially programmed, special purpose hardware. In computer system 200, processor 202 is typically a commercially available processor such as the well-known Core™ class processors available from the Intel Corporation. Many other processors are available, including programmable logic controllers. Such a processor usually executes an operating system which may be, for example, the Windows 10 or Windows 11 operating system available from the Microsoft Corporation, the MAC OS System X available from Apple Computer, the Solaris Operating System available from Sun Microsystems, or UNIX available from various sources. Many other operating systems may be used.

[0090] The processor and operating system together define a computer platform for which application programs in high-level programming languages are w ritten. It should be understood that the invention is not limited to a particular computer system platform, processor, operating system, or network. Also, it should be apparent to those skilled in the art that aspects and embodiments disclosed herein are not limited to a specific programming language or computer system. Further, it should be appreciated that other appropriate programming languages and other appropriate computer systems could also be used.

[0091] One or more portions of the computer system may be distributed across one or more computer systems (not shown) coupled to a communications network. These computer systems also may be general-purpose computer systems. For example, various aspects of the invention may be distributed among one or more computer systems configured to provide a service (e.g., servers) to one or more client computers, or to perform an overall task as part of a distributed system. For example, various aspects and embodiments disclosed herein may be performed on a clientserver system that includes components distributed among one or more server systems that perform vanous functions according to various aspects and embodiments disclosed herein. These components may be executable, intermediate (e.g., IL) or interpreted (e.g., Java) code which communicate over a communication network (e.g., the Internet) using a communication protocol (e.g., TCP / IP). In some embodiments one or more components of the computer system 200 may communicate with one or more other components over a wireless network, including, for example, a cellular telephone network.

[0092] It should be appreciated that the aspects and embodiments disclosed herein are not limited to executing on any particular system or group of systems. Also, it should be appreciated that the aspects and embodiments disclosed herein are not limited to any particular distributed architecture, network, or communication protocol. Various aspects and embodiments disclosed herein may be programmed using an object- oriented programming language, such as SmallTalk, Java, C++, Ada, or C# (C- Sharp). Other object-oriented programming languages may also be used. Alternatively, functional, scripting, and / or logical programming languages may be used, for example, ladder logic. Various aspects and embodiments disclosed herein may be implemented in a non-programmed environment (e.g., documents created in HTML, XML or other format that, when viewed in a window of a browser program, render aspects of a graphical -user interface (GUI) or perform other functions). Various aspects and embodiments disclosed herein may be implemented as programmed or non-programmed elements, or any combination thereof.

[0093] The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. As used herein, the term “plurality” refers to two or more items or components. The terms “comprising,” “including,” “carrying,” “having,” “containing,” and “involving,” whether in the written description or the claims and the like, are open-ended terms, i.e.. to mean “including but not limited to.” Thus, the use of such terms is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items. Only the transitional phrases “consisting of’ and “consisting essentially of,” are closed or semi-closed transitional phrases, respectively, with respect to the claims. Use of ordinal terms such as “first,” “second,” “third,” and the like in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0094] Having thus described several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Any feature described in any embodiment may be included in or substituted for any feature of any other embodiment. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.

Claims

What is claimed is:CLAIMS1 . A system for the generation of hydrogen from a source of aqueous solution, the system comprising: a high fluid velocity electrolyzer having an inlet and an outlet, the inlet of the high fluid velocity electrolyzer fluidly connectable to the source of aqueous solution; and a gas fractionation system fluidly connectable to the outlet of the high fluid velocity electrolyzer.

2. The system of claim 1, wherein the high fluid velocity electrolyzer comprises a concentric tube electrode electrolyzer.

3. The system of claim 2, wherein the high fluid velocity electrolyzer comprises a plurality’ concentric tube electrode electrolyzers fluidically connected in series.

4. The system of claim 1, further comprising a pump configures to flow the aqueous solution through the high fluid velocity electrolyzer at a velocity of at least 2 m / sec.

5. The system of claim 1, wherein the high fluid velocity electrolyzer is configured to generate hydrogen gas and one or more other gasses from the aqueous solution and to direct the generated hydrogen gas and one or more other gasses into the gas fractionation system.

6. The system of claim 5, wherein the gas fractionation system is a cryogenic gas fractionation system configured to separate the hydrogen gas from the one or more other gasses.

7. The system of claim 1, wherein the source of aqueous solution is a source of one of brackish water or seawater.

8. The system of claim 7, further comprising a solids removal apparatus disposed between the source of aqueous solution and the inlet of the high fluid velocity electrolyzer.

9. The system of claim 8, wherein no membrane filtration apparatus are disposed between the source of aqueous solution and the inlet of the high fluid velocity' electrolyzer.

10. The system of claim 8, wherein no biological reactor is disposed between the source of aqueous solution and the inlet of the high fluid velocity electrolyzer.

11. A method for the generation of hydrogen from a source of aqueous liquid, the system comprising: introducing the aqueous solution into an inlet of a high fluid velocity electrolyzer having an inlet and an outlet; withdrawing hydrogen from the outlet of the high fluid velocity' electrolyzer; and purifying the hydrogen in a gas fractionation system fluidly connected to the outlet of the high fluid velocity electrolyzer.

12. The method of claim 11, wherein introducing the aqueous solution into the inlet of the high fluid velocity electrolyzer comprises introducing the aqueous solution into the inlet of a concentric tube electrode electrolyzer.

13. The method of claim 12, introducing the aqueous solution into the inlet of the high fluid velocity electrolyzer comprises introducing the aqueous solution into the inlet of a plurality concentric tube electrode electrolyzers fluidically connected in series.

14. The method of claim 11, further comprising flowing the aqueous solution through the high fluid velocity electrolyzer at a velocity of at least 2 m / sec.

15. The method of claim 11, further comprising: generating hydrogen gas and one or more other gasses from the aqueous solution in the high fluid velocity electrolyzer; and directing the generated hydrogen gas and one or more other gasses into the gas fractionation system.

16. The method of claim 15, wherein directing the generated hydrogen gas and one or more other gasses into the gas fractionation system comprises directing the generated hydrogen gas and one or more other gasses into a cryogenic gas fractionation system configured to separate the hydrogen gas from the one or more other gasses.

17. The method of claim 11, wherein introducing the aqueous solution into the inlet of the high fluid velocity electrolyzer comprises introducing of one of brackish water or seawater into the inlet of the high fluid velocity electrolyzer.

18. The method of claim 12, further comprising removing suspended solids from the aqueous solution upstream of the inlet of the high fluid velocity electrolyzer.

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