Apparatus, system and method for producing nitric oxide

Abstract

The present disclosure provides examples of nitric oxide (NO) generation facilities, systems, and methods. In some embodiments, the NO generation facility may include a reaction chamber having a liquid region and a gas region. The liquid region may be configured to contain a reaction medium, and the gas region may be configured to contain a product gas including NO. The NO generation facility may further include a plurality of electrodes disposed within the reaction medium, and may include an energy source electrically connected to the plurality of electrodes and configured to apply a predetermined voltage or a predetermined current to at least one of the plurality of electrodes to generate NO. The NO generation facility may further include an inlet circuit configured to receive a carrier gas, and may include at least one sparger fluidly connected to the inlet circuit and configured to project bubbles of the carrier gas within the reaction medium.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a division of Chinese Patent Application No. 202011502839.7 filed on December 18, 2020, Chinese Patent Application No. 202011502846.7 filed on December 18, 2020, Chinese Patent Application No. 202011502862.6 filed on December 18, 2020, Chinese Patent Application No. 202011508948.X filed on December 18, 2020, Chinese Patent Application No. 202023064800.X filed on December 18, 2020, Chinese Patent Application No. 202023064847.6 filed on December 18, 2020, This application claims priority to Chinese Patent Application No. 202023064866.9 filed on December 18, 2020, Chinese Patent Application No. 202023072485.5 filed on December 18, 2020, Chinese Patent Application No. 202023072503.X filed on December 18, 2020, Chinese Patent Application No. 202110183873.0 filed on February 18, 2020, Chinese Patent Application No. 202120353644.4 filed on February 8, 2021, and Chinese Patent Application No. 202120353650.X filed on February 8, 2021, all of which are incorporated herein by reference in their entireties.

[0002] The present disclosure relates to equipment, systems and methods for generating and / or delivering nitric oxide, and more particularly to equipment, systems and methods for generating and / or delivering nitric oxide on demand. [Background technology]

[0003] Nitric oxide (NO) is a gas signaling molecule that plays an important role in many physiological and pathological processes. NO can diffuse through cell membranes in the absence of an intermediate transport mechanism, thereby effectively and rapidly signaling neighboring cells or tissues. For example, NO produced by vascular endothelial cells can induce vascular dilation and increased blood flow by signaling surrounding vascular smooth muscle to relax. NO may also be involved in electron transfer and redox reactions among biochemical events in human cells. NO can induce various physiological effects, such as endothelium-dependent vasodilation, by activating guanylate cyclase.

[0004] Inhaled NO can improve the body's oxidative capacity and reduce the need for high-risk extracorporeal cardiopulmonary support in critically ill patients. Controlled use of appropriate doses of inhaled NO can reduce pulmonary artery hypertension and improve oxygenation. The U.S. Food and Drug Administration has approved inhaled NO as a drug for the treatment of persistent pulmonary artery hypertension in newborns. Inhaled NO therapy has also been used in a variety of diseases and clinical fields, such as neonatal respiratory disorders, intensive care medicine, cardiothoracic surgery, acute respiratory distress, and anesthesiology.

[0005] In clinical settings, NO is provided using high-pressure gas tanks or cylinders. The size and weight of such gas tanks are large, and they are typically mounted on wheeled transport devices or carts, typically located near beds in crowded intensive care units. The use of such heavy and bulky gas tanks can pose safety risks to patients and healthcare professionals. For example, patients and healthcare professionals can be exposed to toxic nitrogen dioxide formed during system setup or from potential NO leaks in damaged regulators, valves, or supply lines. Healthcare professionals can also be injured when moving or replacing gas tanks. Therefore, there is a need to overcome and / or resolve one or more of these drawbacks. The present disclosure relates to tankless, or "tankless," systems and methods that can generate NO on an as-needed basis without the need to store large amounts of pressurized NO. Summary of the Invention [Means for solving the problem]

[0006] According to some embodiments of the present disclosure, there is provided an apparatus for producing nitric oxide (NO). In some embodiments, the apparatus may include a reaction chamber having a liquid region and a gas region. The liquid region may be configured to contain a reaction medium. The gas region may be configured to contain a product gas including NO. In some embodiments, the apparatus may include a plurality of electrodes disposed within the reaction medium. The plurality of electrodes may include cathodes. In some embodiments, the apparatus may include an energy source electrically connected to the plurality of electrodes. The energy source may be configured to apply a predetermined voltage or a predetermined current to the cathodes to produce NO. In some embodiments, the apparatus may include a sparger disposed within the reaction medium. In some embodiments, the apparatus may include an inlet circuit. The inlet circuit may be fluidly connected to the sparger and configured to deliver a carrier gas to the sparger. In some embodiments, the apparatus may include an outlet circuit. The outlet circuit may be fluidly connected to the gas region of the reaction chamber and configured to deliver the product gas from the reaction chamber. In certain embodiments, the apparatus can include a first circulation circuit configured to circulate a first fluid flow to the reaction chamber. The first circulation circuit can include a first inlet in fluid communication with a gas region of the reaction chamber, a first outlet in fluid communication with a sparger, and a first pump configured to create a first fluid flow from the first inlet to the first outlet.

[0007] According to one embodiment of the present disclosure, a method for generating nitric oxide is provided. In some embodiments, the method may include applying a preset voltage or a preset current to one or more of a plurality of electrodes by an energy source. The plurality of electrodes may be disposed within a reaction medium contained in a reaction chamber to generate NO. The plurality of electrodes may include a cathode. The reaction chamber may include a gas region and a liquid region. The liquid region may be configured to contain the reaction medium. The gas region may be configured to contain a product gas including NO. In some embodiments, the method may include receiving a carrier gas via an inlet circuit. The inlet circuit may be fluidly connected to a sparger disposed within the reaction medium. In some embodiments, the method may include projecting bubbles of the carrier gas through the reaction medium via the sparger. The bubbles may skim the surfaces of one or more of the plurality of electrodes. In some embodiments, the method may include circulating a first fluid flow through the reaction chamber via a first circulation circuit. The first fluid flow may include a product gas flow. In certain embodiments, the method may include transmitting the product gas from the reaction chamber through an outlet circuit, which may be in fluid communication with a gas region of the reaction chamber.

[0008] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosed embodiments for which protection is sought.

[0009] The drawings constitute a part of this specification, illustrate several embodiments of the present disclosure, and together with the description, serve to explain the principles of any disclosed embodiment as recited in the appended claims. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of an NO system according to some embodiments of the present disclosure. [Figure 2]FIG. 1 is a schematic diagram of an NO generation facility according to some embodiments of the present disclosure. [Figure 3A] FIG. 2 is a schematic diagram of a first electrode, a second electrode, and a sparger according to some embodiments of the present disclosure. [Figure 3B] FIG. 1 is a perspective view of a sparger according to some embodiments of the present disclosure. [Figure 4A] 1 is a graphical representation of the concentration of NO in the product gas produced by an NO production facility according to some embodiments of the present disclosure and the current applied to the electrodes. [Figure 4B] 1 is a graphical representation of the change in concentration of NO over time in a product gas produced by an NO production facility according to some embodiments of the present disclosure. [Figure 4C] 1 is a graphical representation of the concentration of NO in a product gas produced over a period of multiple stages by an NO production facility according to some embodiments of the present disclosure. [Figure 5A] FIG. 1 is an exploded view of a filtration device according to some embodiments of the present disclosure. [Figure 5B] 5B is a cross-sectional perspective view of the filtration device of FIG. 5A. [Figure 5C] FIG. 5B is a cross-sectional view of the filtration device of FIG. 5A. [Figure 6A] FIG. 1 is a perspective view of a pressure vessel according to some embodiments of the present disclosure. [Figure 6B] FIG. 6B is a cross-sectional perspective view of the pressure vessel of FIG. 6A. [Figure 6C] FIG. 6B is another cross-sectional view of the pressure vessel of FIG. 6A. [Figure 7A] 1 is a top perspective view of a waste gas treatment device according to some embodiments of the present disclosure. [Figure 7B] FIG. 7B is a bottom perspective view of the waste gas treatment device of FIG. 7A. [Figure 7C] 7B is a cross-sectional view of the waste gas treatment device of FIG. 7A. [Figure 8A] 1 is an exploded view of a gas converter according to some embodiments of the present disclosure. [Figure 8B] 1 is a schematic diagram of a gas converter according to some embodiments of the present disclosure. [Figure 9]FIG. 1 is a schematic diagram of a ventilation circuit for delivering NO to a patient according to some embodiments of the present disclosure. [Figure 10A] FIG. 1 is a perspective view of a moisture collector according to some embodiments of the present disclosure. [Figure 10B] FIG. 10B is a partial perspective view of the moisture collector of FIG. 10A. [Figure 10C] FIG. 10B is another partial perspective view of the moisture collector of FIG. 10A. [Figure 11A] FIG. 1 is a schematic diagram of a sampling process of a gas monitoring device according to some embodiments of the present disclosure. [Figure 11B] 1 is a schematic diagram of an initialization process for a gas monitor according to some embodiments of the present disclosure. [Figure 11C] 1 is a schematic diagram of a gas monitoring device cleaning process according to some embodiments of the present disclosure. [Figure 11D] 1 is a schematic diagram of a calibration process for a gas monitor according to some embodiments of the present disclosure. [Figure 12] 1 is a flowchart illustrating a method for generating NO according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Reference will now be made in detail to the disclosed embodiments with reference to the drawings. Unless otherwise defined, technical or scientific terms have the meanings commonly understood by those skilled in the art. The disclosed embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosed embodiments. It is to be understood that other embodiments may be utilized and changes may be made without departing from the scope of the disclosed embodiments. Therefore, the materials, methods, and examples are illustrative only and are not intended to be limiting.

[0012] The present disclosure provides apparatus, systems, and methods for generating NO from one or more electrochemical reactions. According to one aspect of the present disclosure, embodiments can output a product gas containing NO. The NO in the product gas can be generated or delivered at a preset concentration and / or flow rate. For example, some embodiments can output a product gas having a clinically relevant concentration and / or flow rate of NO for inhalation or therapeutic use. The concentration and / or flow rate of NO in the product gas can be adjusted. For example, the concentration of NO in the product gas can be in the range of about 0 to about 20,000 ppm.

[0013] In this disclosure, the dimensionless unit "ppm" for describing gas concentration refers to parts per million by volume and can be converted to other concentration units, such as parts per million moles or milligrams per liter (mg / L). In this disclosure, the dimensionless unit "%" or "vol%" for describing gas concentration refers to volume percentage and can be converted to other concentration units, such as weight percentage or molar concentration. As used herein, "about" in a numerical range indicates that the numerical range covers normal industry and subject variations or tolerances for manufacturing and / or operation. As used herein, the phrases "less than," "greater than," "between one value and another value," or "from one value to another value" in a numerical range include all values ​​at, within, or between the endpoints.

[0014] According to another aspect of the present disclosure, an embodiment can permit NO production in stages comprising at least one operating cycle. During the operating cycle, the concentration and / or flow rate of NO in the product gas can reach and / or be maintained at a steady state. As described herein, the concentration and / or flow rate of NO in the product gas at steady state can deviate from a certain value or range due to a steady-state error. For example, the steady-state error can be in a range of about 0 to about 10%. The operating cycle can last, for example, about 60 hours or longer.

[0015] According to another aspect of the present disclosure, embodiments can permit NO production in phases that include at least one ramp period. As described herein, a ramp period can refer to a transient period during which the NO concentration in the product gas can increase or decrease from an initial concentration to a preset steady-state concentration. The ramp period can be a ramp-up period or a ramp-down period. For example, the ramp period can range from about 2 minutes to about 10 minutes. The ramp period can be predetermined or adjusted to permit faster or immediate provision of a stable NO flow, such as may be required in an intensive care unit.

[0016] According to another aspect of the present disclosure, embodiments may permit the generation of NO in multiple stages. Multiple stages of NO generation may be provided to treat the same or different patients over time. Some embodiments of the present invention allow one or more parameters for generating or delivering NO to be predetermined and / or adjusted. For example, the number of stages, the number of operating cycles in a stage, the start and / or end times of an operating cycle, and / or the concentration and / or flow rate of NO in the product gas during an operating cycle of a stage may be predetermined and / or adjusted.

[0017] According to another aspect of the present disclosure, to reduce exposure to health risks, embodiments may reduce or eliminate one or more toxic impurities, such as nitrogen dioxide, that may be present in the product gas.

[0018] Described below are various devices, systems, and methods for producing NO consistent with this disclosure.

[0019] FIG. 1 is a schematic diagram of an NO system 10 according to some embodiments of the present disclosure. As shown in FIG. 1 , in some embodiments, the system 10 includes an NO generation facility 100. The NO generation facility 100 generates NO through one or more electrochemical reactions. In some embodiments, the system 10 includes a carrier gas source 200 located upstream of and in fluid communication with the NO generation facility 100. The carrier gas source 200 can generate or supply a carrier gas 122. The generated NO is then transported to the NO generation facility 100. A carrier gas 122 can be supplied to the NO-generating facility 100 to deliver the NO from the NO-generating facility 100. For example, the carrier gas 122 can sweep, purge, and / or entrain the generated NO from the NO-generating facility 100.

[0020] The NO generation facility 100 can output the generated NO in a product gas. The product gas may include one or more components. In some embodiments, the product gas includes a carrier gas. The product gas can flow from the NO generation facility 100 to one or more downstream systems or devices. The one or more downstream systems or devices can transport, process, and / or store the product gas from the NO generation facility 100. For example, the product gas may include one or more impurities, such as moisture, one or more toxic gases, and solid materials. In some embodiments, the system 10 includes one or more filtration systems or devices for reducing or removing one or more impurities in the product gas. In some embodiments, the system 10 includes a ventilation circuit for delivering NO to a patient in aerobic or anaerobic conditions. Various embodiments of the system 10 and methods for generating NO using the system 10 are described below.

[0021] Electrochemical generation of NO FIG. 2 is a schematic diagram of an NO generation facility 100 according to some embodiments of the present disclosure. The NO generation facility 100 is configured to generate NO from one or more electrochemical reactions in a reaction medium 112. As shown in FIG. 2, in some embodiments, the NO generation facility 100 includes a reaction chamber 102 and a plurality of electrodes. In some embodiments, the reaction chamber 102 includes a liquid region 108 and a gas region 110. The liquid region 108 is configured to receive the reaction medium 112. The gas region 110 is configured to receive gases generated in and / or transported from the reaction medium 112.

[0022] In certain embodiments, the reaction chamber 102 includes a first side 104 and a second side 106. The first side 104 may be a top side of the reaction chamber 102. The second side 106 may be a bottom side of the reaction chamber 102. The first side 104 and the second side 106 may extend parallel to one another. For example, the first side 104 may have a surface that extends parallel to a surface of the second side 106. A liquid region 108 may be disposed proximate the second side 106. A gas region 110 may be disposed proximate the first side 104.

[0023] As shown in FIG. 2 , in some embodiments, the NO generation facility 100 includes an inlet circuit 120 and an outlet circuit 124. The inlet circuit 120 is located downstream of and fluidly connected to a carrier gas source 200. In some embodiments, the inlet circuit 120 has at least one outlet 144, e.g., an opening, in the liquid region 108. The inlet circuit 120 can receive a carrier gas 122 and transport the carrier gas 122 to the liquid region 108. The outlet circuit 124 is located downstream of and fluidly connected to the gas region 110 of the reaction chamber 102. In some embodiments, the outlet circuit 124 has at least one inlet, e.g., an opening, in the gas region 110. For example, the carrier gas 122 can transport the generated NO from the gas region 110 through the outlet circuit 124 and out of the NO generation facility 100.

[0024] In some embodiments, the NO generating system 100 may include one or more NO sensors (not shown) configured to detect the concentration of NO in the product gas. The NO sensor may be located in any suitable location. For example, the NO sensor may be located in contact with the product gas in the gas region 110. In some embodiments, the NO sensor is located in or near the outlet circuit 124 of the reaction chamber 102. For example, the NO sensor may be located at an opening in the outlet circuit 124, such as an inlet or outlet of the outlet circuit 124. For example, the NO sensor may be located within a conduit in the outlet circuit 124. In some embodiments, the NO sensor may be located downstream of the outlet circuit 124 or downstream of one or more filters or filtration devices downstream of the outlet circuit 124. For example, as shown in FIGS. 1 and 2 , the NO sensor 125 may be located downstream of the filter 506 of the filtration system 500, which is located downstream of the outlet circuit 124.

[0025] In some embodiments, the plurality of electrodes of the NO generating facility 100 includes a first electrode 116 and a second electrode 118. The first electrode 116 and the second electrode 118 are disposed within the reaction medium 112. In some embodiments, the second electrode 118 is a counter electrode to the first electrode 116. For example, the first electrode 116 may be a cathode and the second electrode 118 may be an anode, or vice versa. As described herein, some embodiments of the present disclosure are described with respect to the first electrode 116, but similar embodiments for the second electrode 118 will be apparent to those skilled in the art. In some embodiments, the plurality of electrodes includes a reference electrode. The reference electrode may be the first electrode 116, the second electrode 118, or a third electrode (not shown). The reference electrode may be disposed within or outside the reaction medium 112.

[0026] 2, the first electrode 116 and the second electrode 118 are electrically connected to an energy source 114. In some embodiments, the energy source 114 is configured to apply a voltage to the first electrode 116 or to create a potential difference between the first electrode 116 and the second electrode 118. In some embodiments, the energy source 114 is configured to apply a current to the first electrode 116 or to create a current flowing from the second electrode 118 to the first electrode 116, or vice versa. The voltage or current applied to the electrodes can be predetermined and / or adjusted based on one or more conditions (e.g., the desired concentration and / or flow rate of NO in the product gas).

[0027] In some embodiments, the voltage applied to the first electrode 116 may be measured as a potential difference between the first electrode 116 and the second electrode 118, or between the second electrode 118 and the first electrode 116. In some embodiments, the current applied to the first electrode 116 may be measured as a current passing through the first electrode 116. In some embodiments, the voltage applied to the first electrode 116 may be measured as a potential difference between the first electrode 116 and a reference electrode, or between the reference electrode and the first electrode 116.

[0028] In some embodiments, reaction medium 112 is a liquid. For example, reaction medium 112 may include an aqueous solution or an organic solution. In some embodiments, reaction medium 112 includes a nitrite ion source. In some embodiments, NO generation facility 100 generates NO by electrochemically reducing nitrite ions in reaction medium 112 to NO that is proximate to and / or located on the surface of an electrode (e.g., first electrode 116). In some embodiments, one or more catalysts facilitate or enable the electrochemical reduction of nitrite ions to NO. In some embodiments, one or more catalysts are dissolved or dispersed in reaction medium 112. The one or more catalysts are proximate to and / or in contact with the surface of an electrode (e.g., first electrode 116) and may, alone or in combination, mediate electron transfer between the surface of the electrode and nitrite ions in reaction medium 112.

[0029] In some embodiments, the catalyst can be immobilized on the surface of an electrode (e.g., first electrode 116). In some embodiments, the catalyst includes one or more compounds selected from the group including cystine, cysteine, methionine, thiophene, and derivatives thereof. For example, the one or more catalysts can be covalently attached, adsorbed, doped, or covalently attached to a material, such as a polymer, thin film, or hydrogel, deposited on the electrode. Some examples of materials that can be deposited on the electrode are described in PCT / US2018 / 0270 81. As noted herein, PCT / US2018 / 027081 is incorporated herein by reference and is used for related subject matter discussed in this disclosure.

[0030] The catalyst can contribute to the electrochemical reduction of nitrite ions in the reaction medium 112 to NO at and / or near an electrode (e.g., first electrode 116). In some embodiments, the catalyst includes a metal-containing compound, e.g., a metal-ligand complex. In some embodiments, the metal-containing compound can contribute to the electrochemical reduction of nitrite ions in the reaction medium 112 to NO via the following reaction: M(1st valence)(l) + e - → M(divalent)(l) Reaction 1 M(divalent)(l) + NO2 - + 2H + → M(monovalent)(l) + NO + H2O Reaction 2 where M(l) represents a metal-ligand complex, M represents at least one metal ion, l represents at least one surrounding ligand or complexing agent, and NO2 - represents a nitrite ion. NO can be produced by reducing at least one metal ion in a metal-ligand complex from a monovalent to a divalent, where the divalent is less than the monovalent. The reduced metal-ligand complex reduces the nitrite ion in the reaction medium 112 to NO as well as intermediates that are oxidized to the original metal-ligand complex.

[0031] The at least one metal ion may include, for example, one or more metal ions selected from copper, iron, titanium, chromium, manganese, cobalt, and nickel ions. The at least one surrounding ligand or complexing agent may include, for example, one or more selected from tris(2-pyridylmethyl)amine (TPA or TPMA), 1,4,7-triazacyclononane, 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3TACN), tris(2-aminoethyl)amine, 3-((2-aminoethyl)amino)propionic acid, and bis(2-aminopyridine)propionic acid. Some other examples of metal ions, or surrounding ligands or complexing agents, can be found in PCT / US2018 / 027081.

[0032] In some embodiments, using a metal-ligand complex as a catalyst allows for the production of NO and / or the regulation of NO production using a cathodic voltage or cathodic current. In some embodiments, controlling the magnitude of the voltage or current applied to an electrode (e.g., first electrode 116) allows for control of, for example, the ratio of the reduced form of the metal-ligand complex to its oxidized form at and / or near the surface of the electrode. This can allow for control of the amount and / or rate of NO produced at a given concentration of nitrite ions and metal-ligand complex in reaction medium 112.

[0033] In some embodiments, an electrode (e.g., the first electrode 116) may have any suitable shape including one or more surfaces. For example, the first electrode 116 may comprise a plate, sheet, or net. In some embodiments, application of a cathodic voltage or a cathodic current to the first electrode 116 results in the electrochemical production of NO from one or more electrochemical reactions occurring at and / or near one or more surfaces of the first electrode 116. Some or all of the NO produced from the electrochemical reactions at and / or near the surface of the first electrode 116 in the reaction medium 112 can be pumped out of the reaction medium 112 and transported to the gas region 110 of the reaction chamber 102. For example, a carrier gas 122 can be used to sweep, purge, and / or entrain some or all of the NO produced from the reaction medium 112.

[0034] The energy source 114 may include one or more suitable power devices or circuits that allow a voltage or current to be applied to the electrodes, such as an electrical outlet, a power circuit, a DC power source, an AC power source, a generator, or an energy storage device. The energy storage device may include, for example, one or more batteries or fuel cells. In some embodiments, the energy source 114 includes one or more electrical circuits for controlling or regulating the voltage or current applied to the electrodes. In some embodiments, the one or more electrical circuits may include a potentiostat for controlling or regulating the voltage applied to the electrodes. In some embodiments, the one or more electrical circuits may include a galvanostat for controlling or regulating the current passing through the electrodes.

[0035] In some embodiments, the polarity of the first electrode 116 and the second electrode 118 can be switched. For example, the polarity of the first electrode 116 and the second electrode 118 can be switched by reversing the polarity of the energy source 114, reversing the polarity of the voltage or current from a DC power source, for example, by using a reversing switch circuit, or by using an AC power source. For example, the energy source 114 is an AC power source configured to apply a cyclic alternating current or voltage to the electrodes.

[0036] For example, the switching of electrode polarity may be automatically controlled by a software program in the control circuit. Additionally or alternatively, the switching of electrode polarity may be manually controlled by a user, for example, by using a switch. The polarity of the electrodes may be switched during NO production, between two operating cycles, or between two stages. NO in the reaction medium 112 in contact with or adjacent to the electrodes may cause deterioration of the electrodes and may adversely affect the efficiency of NO production. Switching the polarity of the electrodes may increase the effective surface area for NO production and increase the lifespan of the electrodes and / or the NO production equipment 100.

[0037] The electrodes of the NO generating device 100 (e.g., the first electrode 116, the second electrode 118, or the reference electrode) can be made of one or more types of materials. One or more electrodes of the NO generating device 100 can be made of the same material or different materials. In some embodiments, the electrodes of the NO generating device 100 include at least one conductive material. The at least one conductive material can be a metal or a non-metal material. The at least one conductive material can be selected, for example, from a group of conductive materials including platinum, palladium, gold, copper, brass, silver, carbon, glassy carbon, boron-doped diamond (BDD), graphite, stainless steel, titanium, iridium, ruthenium, and one or more alloys thereof, such as a ruthenium-iridium alloy.

[0038] In some embodiments, the electrodes of the NO generating device 100 include at least one substrate. The at least one substrate may be a metal or a non-metal material. The at least one substrate may be selected from a group of materials, including, for example, silicon dioxide, conductive glass, tin-doped indium oxide, fluorine-doped indium oxide, conductive plastic, platinum, gold, copper, brass, silver, carbon, glassy carbon, boron-doped diamond (BDD), graphite, stainless steel, titanium, iridium, ruthenium, and one or more alloys thereof, such as a ruthenium-iridium alloy. In some embodiments, the electrodes of the NO generating device 100 include at least one conductive material applied to the at least one substrate. The at least one conductive material can be applied to the at least one substrate using any suitable plating method, such as electroplating, physical vapor deposition (PVD), chemical vapor deposition (CVD), or plasma-enhanced chemical vapor deposition (PECVD).

[0039] The electrodes (e.g., first electrode 116) of NO generating facility 100 may have any shape, configuration, and / or size. In some embodiments, first electrode 116 provides a surface on and / or near which NO is electrochemically generated. For example, first electrode 116 may be in the form of a plate, sheet, net, or rod. The surface of first electrode 116 may be a surface. The first electrode 116 may have a surface area that may be positively correlated with the rate at which NO is produced at the surface. The first electrode 116 may have a structure that allows for a larger surface area, such as a porous structure.

[0040] 3A is a schematic diagram of a first electrode 116 and a second electrode 118 of an NO generation system 100 according to some embodiments of the present disclosure. The first electrode 116 and the second electrode 118 can be positioned within the reaction chamber 102 using any suitable means, such that the surfaces of the first and second electrodes are disposed within the reaction medium 112. For example, as shown in FIG. 3A , a frame 126 can be used to position the first electrode 116 and the second electrode 118 within the reaction chamber 102. The frame 126 can have a top side connected to the first side 104 of the reaction chamber 102. The first electrode 116 and the second electrode 118 can be attached to the frame 126 in any suitable manner, such as by using screws, snaps, wires, clip fasteners, or any other suitable fastening means.

[0041] In some embodiments, as shown in FIG. 3A , the first electrode 116 and the second electrode 118 comprise two rectangular plates having one or more surfaces 128. The first electrode 116 and the second electrode 118 may have the same or similar sizes. In some embodiments, the first electrode 116 and / or the second electrode 118 have a length of about 3 cm to about 15 cm. In some embodiments, the first electrode 116 and / or the second electrode 118 have a width of about 2 cm to about 10 cm. The first electrode 116 and the second electrode 118 may be spaced apart by any suitable distance, for example, about 0.2 cm to about 10 cm. The first electrode 116 and the second electrode 118 may be spaced apart such that at least a portion of the surface 128 of the first electrode 116 extends along at least a portion of the surface 128 of the second electrode 118, e.g., extends parallel to at least a portion of the surface of the second electrode.

[0042] 1-2, the first electrode 116 and the second electrode 118 are positioned vertically. For example, the first electrode 116 and the second electrode 118 may be disposed perpendicular to the second side 106 of the reaction chamber 102. In some embodiments, each electrode includes a top edge 130 and a bottom edge 132. The top edge 130 may extend along the first side 104 of the reaction chamber 102, e.g., extend parallel to the first side of the reaction chamber. The bottom edge 132 may extend along the second side of the reaction chamber 102, e.g., extend parallel to the second side of the reaction chamber.

[0043] Electrical wires can be used to electrically connect the electrodes to the energy source 114. For example, as shown in FIG. 3A , electrical wires 136 are connected at a first end to the energy source 114 (not shown) and at a second end to an electrode, such as the first electrode 116 or the second electrode 118. The electrical wires 136 can be soldered or brazed to the electrodes (e.g., the first electrode 116 and the second electrode 118). The electrical wires 136 can be made of one or more types of conductive materials (e.g., copper, aluminum, steel, or silver) and can be treated for corrosion protection purposes. In some embodiments, the electrical wires 136 are fastened to the frame 126.

[0044] In some embodiments, the voltage applied to the electrode (e.g., the first electrode 116) is a DC voltage. In some embodiments, the voltage applied to the electrode (e.g., the first electrode 116) ranges from about 1.0 V to about 5.0 V, e.g., from about 1.0 V to about 2.0 V, from about 2.0 V to about 3.0 V, from about 3.0 V to about 4.0 V, from about 4.0 V to about 5.0 V, or a combination thereof.

[0045] In some embodiments, the energy source 114 is configured to apply an excitation voltage to an electrode (e.g., the first electrode 116). In some embodiments, the excitation voltage is about 2 to about 8 times the preset voltage, e.g., about 2 times, about 3 times, about 4 times, about 5 times, about 6 times, about 7 times, or about 8 times.

[0046] In some embodiments, the current applied to the electrode (e.g., the first electrode 116) is a DC current. In some embodiments, the current applied to the electrode (e.g., the first electrode 116) ranges from about 0 mA to about 600 mA, e.g., from about 0 mA to about 10 mA, from about 10 mA to about 50 mA, from about 50 mA to about 100 mA, from about 100 mA to about 200 mA, from about 200 mA to about 300 mA, from about 300 mA to about 400 mA, from about 400 mA to about 500 mA, from about 500 mA to about 600 mA, or a combination thereof.

[0047] In some embodiments, the energy source 114 is configured to apply an excitation current to the first electrode 116. In some embodiments, the excitation current is about 2 to about 8 times the preset current, e.g., about 2 times, about 3 times, about 4 times, about 5 times, about 6 times, about 7 times, or about 8 times.

[0048] Those skilled in the art will recognize that the excitation voltage or excitation current need not be an integer multiple of the preset voltage or preset current, and any number within the range can all meet the objectives disclosed in this disclosure.

[0049] The polarity of the voltage or current can be switched manually or by software and / or hardware control to interchange the polarities of the first electrode 116 and the second electrode 118. In some embodiments, the polarity of the first electrode 116 and the second electrode 118 is switched periodically. For example, the polarity of the first electrode 116 and the second electrode 118 may be switched every about 10 minutes to about 10 hours, e.g., about 5 minutes to about 10 minutes, about 10 minutes to about 30 minutes, about 30 minutes to about 1 hour, about 1 hour to about 2 hours, about 2 hours to about 3 hours, about 3 hours to about 4 hours, about 4 hours to about 5 hours, about 5 hours to about 6 hours, about 6 hours to about 7 hours, about 7 hours to about 8 hours, about 8 hours to about 9 hours, about 9 hours to about 10 hours, or any combination thereof.

[0050] In some embodiments, reaction medium 112 includes at least one buffer or buffer component to regulate, control, or prevent changes in the pH of reaction medium 112. For example, the at least one buffer or buffer component may include one or more organic or inorganic buffers or buffer components selected from the group including sodium hydroxide (NaOH), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), 3-(N-morpholino)propanesulfonic acid (MOPS), citric acid, sodium citrate, tris(hydroxymethyl)aminomethane (Tris), phosphate buffered saline (PBS), boric acid, borax, and boric acid-borax buffer. Some other examples of buffers or buffer components that can be used in reaction medium 112 can be found in PCT / US2018 / 027081.

[0051] The at least one buffer or buffer component in reaction medium 112 may have any suitable concentration. For example, the concentration range of the at least one buffer or buffer component in reaction medium 112 may be from about 0.01 mol / L to about 0.5 mol / L, from about 0.5 mol / L to about 1.0 mol / L, from about 1.0 mol / L to about 1.5 mol / L, from about 1.5 mol / L to about 2.0 mol / L, from about 2.0 mol / L to about 2.5 mol / L, from about 2.5 mol / L to about 3.0 mol / L, or a combination thereof.

[0052] The source of nitrite ions in reaction medium 112 may include one or more nitrite salts. The nitrite salts may be organic or inorganic. Examples of organic nitrite salts include organic ammonium nitrite salts, such as tetramethylammonium nitrite and tetraethylammonium nitrite. Examples of inorganic nitrite salts include metal nitrite salts, such as lithium, sodium, and the like. Nitrites include thorium, potassium, rubidium, calcium, magnesium, aluminum, and iron. Some other examples of nitrite ion sources can be found in PCT / US2018 / 027081. The concentration range of the one or more nitrite salts in reaction medium 112 can be from about 0.01 mol / L to about 0.5 mol / L, from about 0.5 mol / L to about 1.0 mol / L, from about 1.0 mol / L to about 1.5 mol / L, from about 1.5 mol / L to about 2.0 mol / L, from about 2.0 mol / L to about 2.5 mol / L, from about 2.5 mol / L to about 3.0 mol / L, from about 3.0 mol / L to about 3.5 mol / L, from about 3.5 mol / L to about 4.0 mol / L, from about 4.5 mol / L to about 5.0 mol / L, or a combination thereof.

[0053] When the catalyst is dissolved in reaction medium 112, the concentration range of the catalyst in reaction medium 112 may be from about 1 mmol / L to about 5 mmol / L, from about 1 mmol / L to about 10 mmol / L, from about 1 mmol / L to about 15 mmol / L, from about 5 mmol / L to about 10 mmol / L, from about 5 mmol / L to about 15 mmol / L, or from about 10 mmol / L to about 15 mmol / L.

[0054] Reaction medium 112 may include one or more other components. For example, reaction medium 112 may include one or more additives, such as ethylenediaminetetraacetic acid (EDTA), capable of promoting one or more electrochemical reactions to produce NO.

[0055] Embodiments of the NO generation facility 100 may include one or more of the following features to improve the performance of the NO generation facility 100, for example, to increase the reaction rate and / or faradaic efficiency of the NO generation facility 100, increase the concentration of NO in the product gas, or increase the amount or concentration of NO produced using a given amount of reaction medium 112. For example, the faradaic efficiency of the NO generation facility 100 may be in a range of about 70% to about 80% or higher.

[0056] Temperature control of the reaction medium In some embodiments, the reaction medium 112 is maintained at a reaction temperature, near a reaction temperature, or within a temperature range. The electrochemical reaction in the reaction chamber 102 may have the highest, desired, or optimized reaction rate and / or faradaic efficiency at, near, or within a temperature range. The reaction temperature or temperature range can be determined based on one or more conditions, such as buffer and / or catalyst components and concentrations in the reaction medium 112. In some embodiments, the reaction temperature or temperature range may range from about 5° C. to about 10° C., from about 10° C. to about 15° C., from about 15° C. to about 20° C., from about 20° C. to about 25° C., from about 25° C. to about 30° C., from about 20° C. to about 30° C., from about 30° C. to about 35° C., from about 35° C. to about 40° C., from about 40° C. to about 45° C., or a combination thereof.

[0057] In some embodiments, the NO generation facility 100 includes a temperature maintenance device 138 for controlling the temperature of the reaction medium 112. For example, as shown in FIGS. 1-2 , the temperature maintenance device 138 may be located near the reaction chamber 102, such as below, adjacent to, or surrounding the reaction chamber 102. In some embodiments, the temperature maintenance device 138 includes one or more temperature control devices, such as a temperature-controlled water bath, a temperature-controlled oil bath, an air agitation device (e.g., a fan), a heat radiator, or a thermoelectric heating and / or cooling device (e.g., a pn junction device).

[0058] In some embodiments, the NO production facility 100 includes a temperature sensor 140 disposed within the reaction medium 112 and in communication with a temperature maintenance device 138. The temperature maintenance device 138 can monitor the temperature of the reaction medium 112 based on a signal from the temperature sensor 140. The support device 138 can heat or cool the reaction medium 112 in response to the signal. In some embodiments, the voltage or current applied to an electrode (e.g., the first electrode 116) can be adjusted based on a signal from the temperature sensor 140 in the energy source 114. For example, control circuitry in the energy source 114 can be in communication with the temperature sensor 140 and can adjust the amplitude and / or polarity of the voltage or current applied to the first electrode 116.

[0059] Transporting NO from the reaction medium Some or all of the NO produced in reaction medium 112 can be transported out of reaction medium 112. For example, NO produced in reaction medium 112 can be transported, e.g., swept, purged, and / or entrained from reaction medium 112 into gas region 110 using carrier gas 122.

[0060] In some embodiments, as shown in FIG. 2, carrier gas 122 is used to sweep the surface 128 of an electrode (e.g., first electrode 116). Sweeping the surface of the electrode can increase the faradaic efficiency and / or reaction rate of the electrochemical reaction at and / or near the surface of the electrode, and / or can increase the NO concentration in the product gas. For example, in some cases, one or more catalytic metal ions in reaction medium 112, e.g., M (monovalent) ions produced by electrochemical reaction 2, can precipitate into an insoluble form. For example, the catalytic metal ions can be Cu. 2+ In some cases, Cu 2+ can be precipitated from the following reaction, Cu 2+ + 2OH - → Cu(OH)2↓→ CuO + HO Precipitation of catalytic metal ions in the reaction medium 112 can reduce the concentration of catalyst in the reaction medium 112 and can reduce the rate of the electrochemical reaction to produce NO. Precipitation of metal ions causes insoluble forms of the metal ions, such as Cu(OH)2, to deposit on the surface of the electrode. This can reduce the surface area for NO production and can further reduce the lifespan of the electrode. Sweeping the surface of the electrode can increase the movement of materials (e.g., metal ions) at and / or near the surface of the electrode. This can reduce or inhibit surface deposition of metal ions, and therefore increase the rate of NO production and / or the NO concentration in the product gas.

[0061] One or more flow control devices can introduce carrier gas 122 into reaction medium 112. For example, as shown in FIG. 2 , carrier gas source 200 can include flow control device 204 that can measure and control the mass or volumetric flow rate of carrier gas flow 122 introduced into reaction medium 112. Valve 206 can be provided downstream of flow control device 204 to protect flow control device 204. For example, valve 206 can be a check valve configured to prevent backflow of reaction medium 112 from inlet circuit 120 to flow control device 204. Examples of providing carrier gas 122 from carrier gas source 200 to NO production facility 100 are further described below.

[0062] In some embodiments, the carrier gas 122 is introduced into the reaction medium 112 in the form of bubbles propagating along a bubble path. The bubble path can extend along and skim the surface of an electrode (e.g., the surface 128 of the first electrode 116). As the carrier gas bubbles rise to the surface of the reaction medium 112, they can entrain, sweep, and / or purge NOx generated near and / or at the surface 128 of the first electrode 116. The carrier gas bubbles can mix or disturb the reaction medium 112 near the surface 128 of the first electrode 116, and can increase the movement of materials (e.g., metal ions) near the surface. The carrier gas bubbles can purge NOx dissolved in the reaction medium 112 from the reaction medium 112 to the gas region 110.

[0063] In some embodiments, the NO generation facility 100 includes one or more spargers for generating bubbles from the carrier gas 122. As used herein, a sparger may include a device or system configured to project gas bubbles into a liquid. In some cases, a sparger may be referred to as a bubbler. The one or more spargers may be located at any suitable location in the reaction medium 112 to project bubbles of the carrier gas 122 to transport (e.g., sweep, purge, and / or entrain) NO from the reaction medium 112. For example, the one or more spargers may be located above or near the second side 106 of the reaction chamber 102.

[0064] In some embodiments, as shown in FIG. 2 , the NO generation facility 100 includes a first sparger 134 disposed within the reaction medium 112 and proximate to the first electrode 116. In some embodiments, as shown in FIG. 2 , the NO generation facility 100 includes a second sparger 134 disposed proximate to the second electrode 118. In some embodiments, the sparger 134 is configured to receive the carrier gas 122 and project bubbles of the carrier gas that graze one or more surfaces 128 of the first electrode 116 or the second electrode 118. FIG. 3B is a perspective view of the sparger 134 according to some embodiments of the present disclosure. As shown in FIG. 3B , the sparger 134 may have an elongated shape, for example, an elongated cylindrical shape.

[0065] In some embodiments, as shown in FIG. 3A , a sparger 134 may be disposed along the first electrode 116 or the second electrode 118, allowing bubbles emitted from the sparger 134 to propagate upward along one or more surfaces 128 of the first electrode 116 or the second electrode 118. For example, as shown in FIGS. 2 and 3A , the sparger 134 may be disposed between the bottom edge 132 of the first electrode 116 or the second electrode 118 and the second side 106 of the reaction chamber 102. Bubbles emitted from the sparger 134 may propagate along a bubble path extending from the bottom edge 132, through the surface 128, and to the top edge 130 of the first electrode 116 or the second electrode 118. In some embodiments, the sparger 134 may extend along the length of the bottom edge 132, allowing bubbles to graze the entire surface 128 of the first electrode 116.

[0066] In some embodiments, the distance between the sparger 134 and the first electrode 116 or the second electrode 118 can be selected to increase the coverage and / or efficiency of the sweep on one or more surfaces of the electrodes. The sparger 134 can be positioned a distance from the electrode, for example, less than about 1 cm, less than about 5 mm, less than about 2 mm, less than about 1 mm, or less than about 0.5 mm.

[0067] The sparger 134 may have any suitable structure for receiving gas and projecting gas bubbles. In some embodiments, the sparger 134 includes a porous structure 141 that provides a plurality of holes for projecting gas bubbles. For example, as shown in FIG. 3B , the sparger 134 may include a lumen 142 surrounded by the porous structure 141. Gas can flow through the lumen 142 and bubble through the holes in the porous structure 141. The lumen 142 may have a tubular shape extending from a first opening to a second opening. The lumen 142 may or may not extend along the centerline of the sparger 134. The lumen 142 may have a diameter selected based on one or more conditions, such as the flow rate of the received gas and the desired density and / or size of the bubbles. For example, the lumen 142 may have a diameter ranging from about 1 mm to about 9 mm, e.g., from about 1 mm to about 2 mm, from about 2 mm to about 3 mm, from about 3 mm to about 4 mm, from about 4 mm to about 5 mm, from about 5 mm to about 6 mm, from about 6 mm to about 7 mm, from about 7 mm to about 8 mm, from about 8 mm to about 9 mm, or a combination thereof.

[0068] 2 and 3A, outlet 144 of inlet circuit 120 is fluidly connected to sparger 134 (e.g., lumen 142 of sparger 134). Carrier gas 122 can flow from carrier gas source 200 through inlet circuit 120 to sparger 134 via outlet 144. In some embodiments, sparger 134 is attached to a sparger mount 148. In some embodiments, sparger mount 148 is attached to frame 126. Sparger mount 148 can allow sparger 134 to be positioned as desired.

[0069] In some embodiments, the sparger mount 148 may include one or more structures for guiding the flow of gas bubbles. For example, the sparger mount 148 may include a shell having one or more openings configured to guide gas bubbles emitted from the sparger 134 toward one or more surfaces 128 of the electrode. For example, as shown in FIG. 3A , the sparger mount 148 may include an opening located at the top and / or upper portion of the sparger 134, allowing gas bubbles to be emitted from the upper portion of the sparger 134 and propagate along the surface 128 of the first electrode 116. The sparger mount 148 may include one or more blocking or sealing components to prevent one or more portions of the sparger 134 from emitting gas or gas bubbles. For example, the sparger mount 148 may have a portion configured to prevent gas from exiting the lumen 142 directly without passing through the porous structure 141. For example, sparger mount 148 may have a portion that blocks or seals a first end of bore 142 , the first end opposing a second end connected to outlet 144 .

[0070] In some embodiments, the sparger 134 includes at least one porous material that provides the porous structure 141. The density and / or size of the bubbles can depend on one or more conditions, such as air pressure, gas flow rate, and the density and / or size of the pores in the at least one porous material. At a given gas flow rate, small pores can allow the sparger 134 to generate small bubbles with a high density. The at least one porous material may include a metallic material, such as stainless steel. The at least one porous material may include a non-metallic material. The non-metallic material may be a polymeric material, such as polyethylene (PE), polycarbonate (PC), polyvinylidene fluoride (PVDF), ceramic, quartz, or silicon carbide.

[0071] The pore size of the at least one porous material of the sparger 134 can be selected based on the desired density, size, and / or flow rate of the bubbles. For example, pore size ranges can include from about 0.1 μm to about 0.5 μm, from about 0.1 μm to about 0.2 μm, from about 0.2 μm to about 0.5 μm, from about 0.5 μm to about 1 μm, from about 1.0 μm to about 10 μm, from about 10 μm to about 20 μm, from about 20 μm to about 50 μm, from about 50 μm to about 100 μm, from about 100 μm to about 150 μm, and from about 150 μm to about 200 μm. from about 200 μm, from about 200 μm to about 300 μm, from about 300 μm to about 400 μm, from about 400 μm to about 500 μm, from about 500 μm to about 600 μm, from about 600 μm to about 700 μm, from about 700 μm to about 800 μm, from about 800 μm to about 900 μm, from about 900 μm to about 1 mm, or a combination thereof.

[0072] The porous material of the sparger 134 may have a certain thickness through which gas flow can generate bubbles. The thickness of the porous material can be measured from the inner surface to the outer surface of the porous material. Increasing the thickness of the porous material can increase the resistance to gas flow and reduce foaming efficiency. Decreasing the thickness of the porous material can reduce the density and / or velocity of the bubbles. For sweeping the surface of the electrode, The thickness of the porous material can be selected to obtain any suitable density and / or size of cells, for example, the thickness of the porous material can range from about 0.5 mm to about 1 mm, from about 1 mm to about 2 mm, from about 2 mm to about 3 mm, from about 3 mm to about 4 mm, from about 4 mm to about 5 mm, from about 5 mm to about 6 mm, from about 6 mm to about 7 mm, from about 7 mm to about 8 mm, from about 8 mm to about 9 mm, from about 9 mm to about 10 mm, or a combination thereof.

[0073] Carrier gas generation In some embodiments, the carrier gas 122 is generated or supplied from a carrier gas source 200. The carrier gas 122 may include any suitable gas, such as air, nitrogen gas, helium gas, argon gas, and oxygen gas. In some embodiments, the carrier gas 122 includes nitrogen gas. In some embodiments, the concentration of nitrogen gas in the carrier gas 122 is about 99.0% by volume or greater than 99.0% by volume. For example, the concentration of nitrogen gas in the carrier gas 122 may be about 99.10%, 99.20%, 99.30%, 99.40%, 99.50%, 99.60%, 99.70%, 99.80%, 99.90%, 99.95%, 99.98%, or 99.99% by volume, or greater. The carrier gas 122 may contain oxygen gas. For example, the concentration of oxygen gas in the carrier gas 122 may be less than about 1%, 0.5%, or 0.1%.

[0074] In some embodiments, as shown in FIG. 1 , the carrier gas source 200 includes a nitrogen gas generation facility 202 configured to generate the carrier gas 122 from compressed air. In some embodiments, the compressed air is supplied to the carrier gas source 200 from an air compressor system or a reservoir. In some embodiments, the compressed air is filtered before being supplied to the carrier gas source 200. For example, the carrier gas source 200 may include a filtration facility located upstream of and configured to be fluidly connected to the nitrogen gas generation facility 202. The filtration facility may include one or more filters, such as a dust filter and a moisture filter. In some embodiments, the carrier gas source 200 includes a pressure sensor and a pressure controller, such as a pressure regulator or a pressure control valve. The pressure controller may adjust and control the pressure and / or flow rate of the compressed air entering the nitrogen gas generation facility 202 based on a response or signal from the pressure sensor.

[0075] The nitrogen gas generation facility 202 may include one or more suitable devices for generating nitrogen gas from compressed air. In some embodiments, the nitrogen gas generation facility 202 includes at least one carbon molecular sieve (CMS). The carbon molecular sieve may have a pore size distribution that permits separation of nitrogen gas from air. In some embodiments, the nitrogen gas generation facility 202 includes at least one nitrogen gas separation membrane. The nitrogen gas separation membrane can separate nitrogen gas from air based on the permeation rates of nitrogen gas and oxygen gas through the membrane wall. The nitrogen gas separation membrane may have any suitable configuration. In some embodiments, the nitrogen gas separation membrane includes at least one bundle of selectively permeable hollow fibers.

[0076] The nitrogen gas separation membrane may comprise one or more materials selected from the group consisting of poly(4-methyl-1-pentene), brominated polycarbonate, polypropylene, polyimide, and polydimethylsiloxane. In some embodiments, the nitrogen gas separation membrane comprises a plurality of pores having an average pore size ranging from about 0.005 μm to about 0.007 μm, from about 0.007 μm to about 0.01 μm, from about 0.01 μm to about 0.013 μm, from about 0.013 μm to about 0.015 μm, from about 0.015 μm to about 0.017 μm, from about 0.017 μm to about 0.019 μm, from about 0.019 μm to about 0.02 μm, or a combination thereof.

[0077] As described herein, the description of the nitrogen gas generation system 202 generally applies to systems that generate other carrier gases (e.g., helium gas, argon gas, and oxygen gas) and will be apparent to those skilled in the art.

[0078] In some embodiments, the nitrogen gas generation facility 202 is located upstream of and fluidly connected to the inlet circuit 120. In some embodiments, as shown in FIG. 1 , the carrier gas source 200 further includes a flow controller 204 located downstream of the nitrogen gas generation facility 202 and upstream of the inlet circuit 120. The flow controller 204 may be configured to control the flow rate of the carrier gas 122 entering the NO generation facility 100. Increasing the flow rate of the carrier gas 122 can increase the NO production rate and / or the concentration of NO in the product gas. For example, increasing the flow rate of the carrier gas 122 can increase the sweep of the carrier gas 122 across the surface of the first electrode 116 and increase the rate at which the generated NO is transported out of the reaction medium 112. In some embodiments, the flow rate of the product gas of the NO generation facility 100 output from the outlet circuit 124 is proportional to the flow rate of the carrier gas 122.

[0079] Recirculation of product gas to the reaction chamber 2 , the NO generation system 100 includes a gas circulation circuit 300. In some embodiments, the gas circulation circuit 300 includes a circulation inlet 302 and a circulation outlet 304. In some embodiments, the circulation inlet 302 is fluidly connected to the gas region 110 of the reaction chamber 102. For example, the circulation inlet 302 may include an opening disposed within a wall of the gas region 110 or in a wall of the gas region. In some embodiments, the circulation outlet 304 is fluidly connected to the liquid region 108 of the reaction chamber 102. For example, the circulation outlet 304 may be fluidly connected to the inlet circuit 120. For example, the circulation outlet 304 may include an opening disposed within a wall of the liquid region 108 or in a wall of the liquid region.

[0080] In some embodiments, the product gas in the gas region 110 is recycled to the reaction chamber 102 from a circulation inlet 302 to a circulation outlet 304. For example, the recycled product gas 303 can flow from the circulation inlet 302 to the circulation outlet 304. In some embodiments, the gas circulation circuit 300 includes a gas pump 306 configured to generate the recycled product gas flow 303. The gas pump 306 may be located downstream of the circulation inlet 302 and upstream of the circulation outlet 304.

[0081] 2 , the gas circulation circuit 300 is fluidly connected to the outlet circuit 124 of the NO generation facility 100. For example, the circulation inlet 302 of the gas circulation circuit 300 may be fluidly connected to the outlet circuit 124. The gas circulation circuit 300 and the outlet circuit 124 may have a common inlet, such as the circulation inlet 302. The gas circulation circuit 300 and the outlet circuit 124 may have a common fluid path. In some embodiments, the gas circulation circuit 300 includes a first filtration device 508 disposed downstream of the circulation inlet 302. The common fluid path may extend from the common inlet to the first filtration device 508.

[0082] In some embodiments, a first filtration device 508 is provided upstream of the gas pump 306. The filtration device 508 can reduce or remove liquid and / or solid materials in the recirculating product gas 303. In some embodiments, the gas circulation circuit 300 includes a second filtration device 307. The second filtration device 307 can include a capsule filter or a membrane filter. The second filtration device 307 can remove one or more types of impurities (e.g., liquid and solid materials) in the recirculating product gas 303 and protect the gas pump 306.

[0083] The recycled product gas 303 can be introduced to the surface of the electrode and can be allowed to skim the surface of the electrode. In some embodiments, the circulation outlet 304 is in fluid communication with the sparger 134. For example, the circulation outlet 304 can be fluidly connected to the lumen 142 of the sparger 134. A gas pump 306 can be provided downstream of the circulation inlet 302 and upstream of the sparger 134, and the recycled product gas 303 can flow from the circulation inlet 302 to the lumen 142 of the sparger 134.

[0084] In some embodiments, as shown in FIG. 2 , the recycled product gas 303 is combined with the carrier gas 122 to form the gas flow 146. For example, the gas circulation circuit 300 may include a three-way connector 308. The three-way connector 308 is fluidly connectable to the circulation outlet 304 and configured to receive the recycled product gas 303. The three-way connector 308 is fluidly connectable to the carrier gas source 200 and / or the inlet circuit 120 and configured to receive the carrier gas 122. The three-way connector 308 can combine the received recycled product gas 303 and the carrier gas 122 to form the gas flow 146. The three-way connector 308 may include any suitable structure, such as a three-way fitting or a three-way valve. The gas flow 146 can be supplied to a sparger 134 to generate bubbles to skim the surface of the electrode.

[0085] In certain embodiments, the gas circulation circuit 300 may include a valve 206. The valve 206 may be located upstream of the circulation outlet 304. The valve 206 may be located downstream of the gas pump 306 and downstream of the three-way connector 308. The valve 206 may prevent backflow of the gas flow 146 and / or backflow of the reaction medium 112 from the reaction chamber 102 to the gas pump 306. The gas flow 146 may flow through the valve 206 to the circulation outlet 304 and the outlet 144 and be supplied to one or more spargers 134. The one or more spargers 134 may also project gas bubbles from the gas flow 146 to transport (e.g., sweep, purge, and / or entrain) NO produced in the reaction medium 112 to the gas region 110. For example, in some embodiments, the sparger 134 projects bubbles from the gas flow 146 to graze the surface of an electrode (eg, the first electrode 116).

[0086] The product gas in the gas region 110 may include carrier gas 122 and the generated NO. In some embodiments, recycling the product gas in the gas region 110 allows the carrier gas 122 in the product gas to be recycled to the surface of the electrode. Recycling the carrier gas can reduce the amount of carrier gas required to support the generation of NO, for example, the amount of carrier gas required to sweep past the first electrode 116 and / or transport the generated NO. Recycling the product gas can allow NO to accumulate in the product gas in the gas region 110 of the reaction chamber 102, allowing for a higher concentration of NO in the product gas in the gas region 110. This can allow for a higher and / or more stable concentration of NO in the product gas delivered from the gas region 110 of the NO generation facility 100.

[0087] 4A is a graphical representation of the concentration of NO in the product gas and the current applied to the first electrode 116 according to some embodiments of the present disclosure. In this example, the NO generation system 100 may include a reaction chamber 102 having a gas region and a liquid region, a reaction medium 112 contained in the liquid region, a first electrode 116 and a second electrode 118 disposed within the reaction medium 112, a sparger 134 for sparging the surface of the first electrode 116, a gas circulation circuit 300 for recirculating the product gas, and the sparger 134 for sparging the first electrode 116. The electrodes may each be made of stainless steel and may each include a plate having a surface area of ​​about 5 cm by about 6 cm. The reaction medium 112 may include about 1.0 mol / L NaNO, about 7 mmol / L CuSO, about 7 mmol / L MeTACN, and about 0.5 mol / L HEPES buffer. An appropriate alkaline solution (e.g., NaOH solution) can be titrated against the HEPES buffer solution, thereby allowing the reaction medium 112 to have a pH value of about 6 to about 8, e.g., about 7.2. The sparger 134 can be cylindrical, having a length of about 7 cm, an inner diameter of about 5 mm, and an outer diameter of about 10 mm, and the average pore size of the sparger is about 20 μm. A carrier gas 122 containing N2 at a concentration of about 99.7% by volume at a flow rate of about 300 mL / min can be introduced into the sparger 134. The gas circulation circuit 300 can recirculate the product gas at a flow rate of about 3 L / min. As shown in FIG. 4A, the concentration of NO in the product gas can be increased by increasing the current applied to the first electrode 116 from about 0 mA to about 300 mA. In this example, fitting the data to a linear regression model revealed that for each 1 mA of applied current, the concentration of NO in the product gas can increase by approximately 36.1 ppm, and the NO generating system 100 can have a faradaic efficiency of 70.7%. By reducing the sweep to the first electrode 116, the increase in NO concentration per unit of applied current can be reduced, and the faradaic efficiency can be lowered.

[0088] 4B is a graphical representation of the change over time in the concentration of NO in the product gas generated by the NO generation system 100 according to some embodiments of the present disclosure. In this example, the NO generation system 100 may have the same reaction conditions as those described in the above-referenced example of FIG. 4A, except that an initial current of about 300 mA is applied within a ramp period of about 2 minutes, followed by a current of 100 mA applied to the first electrode 116 for about 60 hours. After the ramp period, the concentration of NO in the product gas of the NO generation system 100 increases to about 3600 ppm and remains at 3600 ppm or a steady-state concentration of about 3600 ppm for about 60 hours. With such a quantity of NO produced, about four to five gas tanks would typically be required to store about 8 L of compressed NO, which has an NO concentration of about 800 ppm at a pressure of about 13.8 MPa. Sweeping the surface of the first electrode 116 using the sparger 134 and recirculating the product gas through the gas circulation circuit 300 allows for the production of NO at a stable concentration over a long period of time. The amount of NO that can be produced by the NO production system 100 has, for example, a product gas with an NO concentration of about 3600 ppm within about 60 hours.

[0089] Separating NO from the reaction medium Before treating, replacing, or replenishing the reaction medium 112 of the NO-producing facility 100, the reaction medium can be used repeatedly to produce NO. For example, the reaction medium 112 of the NO-producing facility 100 can be used to produce NO within multiple operating cycles in a single stage or in multiple stages. Some of the produced NO can dissolve in the reaction medium 112 after an operating cycle or a single stage. The NO dissolved in the reaction medium 112 can reduce the concentration and / or amount of NO that can be produced by repeated use of the reaction medium 112 and can increase the waiting time between stages or operating cycles.

[0090] For example, NO dissolved in reaction medium 112 can interact with a metal-ligand complex catalyst, such as Cu(II)-1,4,7-trimethyl-1,4,7-triazacyclononane (Cu(Me3TACN)). For example, during the waiting period between two stages, NO dissolved in reaction medium 112 can bind to the central copper ion of Cu(Me3TACN). This can reduce the concentration of the metal-ligand complex in reaction medium 112 used to catalyze the electrochemical reaction to produce NO in the next stage, and can reduce the reaction rate of the next stage and / or the concentration of NO in the product gas. In some cases, the concentration of NO in the product gas of one stage can be lower than the concentration of NO in the product gas of the previous stage, e.g., by about 10% to about 30% lower.

[0091] In some embodiments, one or more spars disposed within reaction medium 112 The sparger 134 can generate gas bubbles to purge dissolved NO from the reaction medium 112 into the gas region 110 and reduce the amount of NO dissolved in the reaction medium 112. In some embodiments, the dissolved NO in the reaction medium 112 can be reduced by sweeping the surface of the electrode. For example, the sparger 134 can generate gas bubbles that propagate along and brush against the surface 128 of the first electrode 116. The gas bubbles can entrain and / or sweep NO generated at and / or near the surface of the first electrode 116 out of the reaction medium 112, which can reduce or prevent the generated NO from dissolving in the reaction medium 112.

[0092] 1 and 2, the NO production facility 100 includes a liquid-gas separation circuit 400 for reducing or removing NO dissolved in the reaction medium 112. The liquid-gas separation circuit 400 is configured to circulate a fluid flow (e.g., a liquid flow or a gas flow) to the reaction chamber 102. The liquid-gas separation circuit 400 can be used before, during, and / or after repeated use of the reaction medium 112 to produce NO.

[0093] 2 , the liquid-gas separation circuit 400 includes a first port 402 and a second port 410. In some embodiments, the first port 402 is fluidly connected to the liquid region 108. The first port 402 may include an opening in the liquid region 108 of the reaction chamber 102 (e.g., below the horizontal surface of the reaction medium 112). In some embodiments, the second port 410 is fluidly connected to the gas region 110. The second port 410 may include an opening in the gas region 110 of the reaction chamber 102 (e.g., above the horizontal surface of the reaction medium 112). In some embodiments, the liquid-gas separation circuit 400 is configured to circulate the reaction medium flow 112 to the reaction chamber 102 from the first port 402 to the second port 410. In some embodiments, the liquid-gas separation circuit 400 is configured to circulate the product gas flow to the reaction chamber 102 from the second port 410 to the first port 402.

[0094] In some embodiments, the liquid-gas separation circuit 400 includes a pump 406. In some embodiments, the pump 406 is a dual-purpose liquid-gas pump. In some embodiments, the pump 406 is a reversible pump. The pump 406 can cause a fluid flow from the first port 402 to the second port 410 or from the second port 410 to the first port 402. In some embodiments, the fluid flow is a liquid flow. For example, the pump 406 can cause a reaction medium flow 112 from the first port 402 to the second port 410. In some embodiments, the fluid flow is a gas flow. For example, the pump 406 can cause a product gas flow from the second port 410 to the first port 402.

[0095] The pump 406 can generate a fluid flow at any suitable rate. For example, the pump 406 can generate a fluid flow (e.g., a reaction medium flow) at a constant rate ranging from about 0.25 L / min to about 10 L / min, e.g., from about 0.5 L / min to about 1.0 L / min, from about 1.0 L / min to about 1.5 L / min, from about 1.5 L / min to about 2.0 L / min, from about 2.0 L / min to about 2.5 L / min, from about 2.5 L / min to about 3.0 L / min, from about 3.0 L / min to about 3.5 L / min, from about 3.5 L / min to about 4.0 L / min, and from about 4.0 L / min to about 4.5 L / min. from about 4.5 L / min to about 5.0 L / min, from about 5.0 L / min to about 5.5 L / min, from about 5.5 L / min to about 6.0 L / min, from about 6.0 L / min to about 6.5 L / min, from about 6.5 L / min to about 7.0 L / min, from about 7.0 L / min to about 7.5 L / min, from about 7.5 L / min to about 8.0 L / min, from about 8.0 L / min to about 8.5 L / min, from about 8.5 L / min to about 9 L / min, from about 9.0 L / min to about 9.5 L / min, from about 9.5 L / min to about 10 L / min, or a combination thereof.

[0096] 1 and 2 , the liquid-gas separation circuit 400 includes a liquid-gas separator 408. In some embodiments, the liquid-gas separator 408 is disposed between the first port 402 and the second port 410. The liquid-gas separator 408 may be disposed downstream or upstream of the pump 406. In some embodiments, the liquid-gas separator 408 includes at least one first chamber 414 and at least one second chamber 416. The first chamber 414 and / or the second chamber 416 may have any suitable shape and size. For example, the first chamber 414 and / or the second chamber 416 may have a tubular structure. The first chamber 414 may be received in the second chamber 416, or vice versa. In some embodiments, the liquid-gas separator 408 includes a shell or housing configured to enclose the first chamber 414 and the second chamber 416.

[0097] In some embodiments, the first chamber 414 and the second chamber 416 are separated by a separation membrane. The separation membrane may comprise a material permeable to NO. For example, the separation membrane may comprise a material such as polydimethylsiloxane (PDMS), silicone resin, or polypropylene. NO can diffuse from the liquid in the first chamber 414 through the separation membrane to the gas in the second chamber 416. The separation membrane may have any suitable configuration, for example, a plurality of hollow fibers with walls formed from the separation membrane.

[0098] The separation membrane can be selected to have any suitable area that allows for the reduction or removal of NO dissolved in the reaction medium 112 within a certain cycle and / or circulation rate. In some embodiments, the separation membrane of the liquid-gas separator 408 has a surface area in the range of about 500 cm. 2 from approximately 50,000 cm 2 For example, up to about 500 cm 2 Approximately 1000cm from 2 Approximately 1000cm 2 Approximately 5000cm from 2 Approximately 5000cm 2from about 10,000 cm 2 Up to about 10,000 cm 2 from about 15,000 cm 2 Up to about 15,000 cm 2 from about 20,000 cm 2 Up to about 20,000 cm 2 from approximately 25,000 cm 2 Up to approximately 25,000 cm 2 from approximately 30,000 cm 2 Up to about 30,000 cm 2 from approximately 35,000 cm 2 Up to about 35,000 cm 2 from about 40,000 cm 2 Up to about 40,000 cm 2 from approximately 45,000 cm 2 Up to about 45,000 cm 2 from approximately 50,000 cm 2 or a combination thereof.

[0099] In some embodiments, the first chamber 414 includes an inlet 418 and an outlet 420. The pump 406 can drive the reaction medium 112 from the inlet 418 through the first chamber 414 to the outlet 420. As the reaction medium 112 flows through the first chamber 414, NO dissolved in the reaction medium 112 can diffuse through the separation membrane to the second chamber 416. In some embodiments, the second chamber 416 includes an inlet 422 and an outlet 426. A sweep gas can flow from the inlet 422 through the second chamber 416 to the outlet 426. The sweep gas can deliver the NO that diffused into the second chamber 416 as a mixed gas through the outlet 426. The mixed gas can be delivered to the waste gas treatment device 700, as described further below.

[0100] The sweep gas may include any suitable gas, such as air, oxygen gas, nitrogen gas, or a combination thereof. The sweep gas may be supplied to the inlet 422 from a gas source (e.g., the carrier gas source 200). In some embodiments, the carrier gas 122 is used as the sweep gas. For example, the fluid controller 424 may be used to control the flow of the carrier gas 122 from the carrier gas source 200 to the inlet 422. The fluid controller 424 may include a pressure controller, such as a pressure control valve or a pressure regulator.

[0101] 2, the NO production facility 100 includes a filtration device 412. In some embodiments, the filtration device 412 is located upstream of the liquid-gas separation device 408. The filtration device 412 may include one or more filters configured to filter one or more impurities (e.g., solid materials) from the reaction medium 112. The filtration device 412 may protect a separation membrane of the liquid-gas separation device 408 from being damaged by impurities in the reaction medium 112 when the reaction medium 112 flows through the liquid-gas separation device 408.

[0102] In certain embodiments, the liquid-gas separation circuit 400 has a working mode and a cleaning mode. In the working mode, the liquid-gas separation circuit 400 can reduce or remove NO dissolved in the reaction medium 112 by circulating the reaction medium 112 from the first port 402 through the liquid-gas separator 408 to the second port 410. In the cleaning mode, gas in the gas region 110 of the reaction chamber 102 can be circulated from the second port 410 through the liquid-gas separator 408 to the first port 402. After the working mode, the remaining reaction medium 112 in the liquid-gas separator 408 can be sent back to the reaction chamber 102 by circulating the gas through the liquid-gas separator 408. For example, the pump 406 can generate a fluid flow (e.g., a gas flow in the gas region 110) at a constant flow rate ranging from about 0.25 L / min to about 5 L / min, e.g., from about 0.25 L / min to about 0.5 L / min, from about 0.5 L / min to about 1.0 L / min, from about 1.0 L / min to about 1.5 L / min, from about 1.5 L / min to about 2.0 L / min, from about 2.0 L / min to about 2.5 L / min, from about 2.5 L / min to about 3.0 L / min, from about 3.0 L / min to about 3.5 L / min, from about 3.5 L / min to about 4.0 L / min, from about 4.0 L / min to about 4.5 L / min, from about 4.5 L / min to about 5.0 L / min, or a combination thereof. The cleaning mode can reduce losses of the reaction medium 112 and can extend the life of the reaction medium 112 and / or the NO production equipment 100. The cleaning mode can dry the separation membrane to prepare it for the next operating mode.

[0103] 2, the liquid-gas separation circuit 400 includes a selector valve 404 for switching the liquid-gas separation circuit 400 between a working mode and a cleaning mode. In some embodiments, the selector valve 404 includes one or more valves configured to control the direction of fluid flow in the liquid-gas separation circuit 400. For example, the selector valve 404 may include a group of normally closed valves, and the selector valve may change the direction of fluid flow in the liquid-gas separation circuit 400 by opening different subsets of the valves. In such cases, the pump 406 does not necessarily operate as a reversible pump in the working mode and the cleaning mode.

[0104] 2, the selector valve 404 may include a group of four valves 404a-404d. In some cases, the valve 404a is disposed between the first port 402 and the pump 406, the valve 404b is disposed between the first port 402 and the fluid outlet 420 of the first chamber 414, the valve 404c is disposed between the second port 410 and the pump 406, and the valve 404d is disposed between the second port 410 and the fluid outlet 420 of the first chamber 414. For example, in the working mode, the valves 404a and 404d are opened, and the valves 404b and 404c are closed. The reaction medium 112 can flow from the first port 402 through the valve 404a, the pump 406, the fluid inlet 418 and the fluid outlet 420 of the liquid-gas separator 408, and the valve 404d to the second port 410. For example, in a cleaning mode, valves 404a and 404d are closed and valves 404b and 404c are open. Gas in the gas region 110 of the reaction chamber 102 can flow from the second port 410 through valve 404c, pump 406, fluid inlet 418 and fluid outlet 420 of the liquid-gas separator 408, and valve 404b to the first port 402.

[0105] In some embodiments, the liquid-gas separation circuit 400 includes a solenoid valve (not shown), which may be located upstream of the liquid-gas separation device 408. The solenoid valve can prevent the reaction medium 112 from entering the liquid-gas separation device 408 due to pressure that can build up in the reaction medium 112 during the electrochemical production of NO.

[0106] 4C is a graphical representation of the concentration of NO in the product gas produced over multiple stages by an NO generation system 100 according to some embodiments of the present disclosure. In this example, the NO generation system 100 may have the same reaction conditions as those described in the above-referenced example of FIG. 4A, with an initial application of about 150 mA of current within a ramp period of about 2 minutes in multiple stages, followed by application of 50 mA of current to the first electrode 116. The NO generation system 100 may further include a liquid-gas separation circuit 400. In each stage, after terminating the current applied to the first electrode 116, the liquid-gas separation circuit 400 may operate in a working mode, circulating the reaction medium 112 through a liquid-gas separation device 408 at a flow rate of about 0.5 L / min for about 10 minutes to reduce or remove NO dissolved in the reaction medium 112. Thereafter, the liquid-gas separation circuit 400 can be operated in a cleaning mode, and the liquid-gas separation circuit circulates the gas in the gas region 110 through the liquid-gas separation device 408 at a flow rate of about 1 L / min for about 0.5 minutes. As shown in Figure 4C, the NO production system 100 using the reaction medium 112 can produce a product gas having an NO concentration of about 2000 ppm in five successive stages.

[0107] Several examples of NO systems are provided below. In some examples, the NO system 10 may include an NO generation facility 100 and a carrier gas source 200. The NO generation facility 100 may include a reaction chamber 102 having a gas region and a liquid region, a reaction medium 112 contained in the liquid region, a cathode and an anode disposed in the reaction medium 112, two spargers 134, a gas circulation circuit 300, and a liquid-gas separation circuit 400. The spargers 134 may be disposed near the two electrodes, respectively, and are configured to emit gas bubbles to propagate on the surfaces of the electrodes. The carrier gas source 200 may generate a carrier gas 122 from compressed air. The carrier gas source 200 may include a moisture filter and a dust filter to reduce or remove moisture and solid matter in the compressed air. The carrier gas source 200 may further include a nitrogen gas generation facility 202, which has a nitrogen gas separation membrane for separating N from the compressed air. The cathode and anode can be electrically connected to a power source. The power source can apply a current or voltage to the cathode, and NOx can be generated at or near the surface of the cathode and swept or entrained into the gas region by the carrier gas 122, thereby generating a product gas. The gas circulation circuit 300 can recycle the product gas from the gas region to the sparger. The recycle gas can be combined with the carrier gas 122 and introduced into the sparger. The liquid-gas separation circuit 400 can include a liquid-gas separator 408 for separating NOx dissolved in the reaction medium after terminating the application of the voltage or current to the cathode while applying a current or voltage to the cathode. The liquid-gas separator 408 can include a separation membrane having a surface area. The liquid-gas separation circuit 400 can operate in a working mode during a first cycle and in a cleaning mode during a second cycle following the first cycle.

[0108] For example, the cathode and anode may be made of platinum. The reaction medium may contain about 0.01 mol / L HEPES buffer, about 0.01 mol / L sodium nitrite, and about 1 mmol / L The reaction mixture may include copper-tris(2-pyridylmethyl)amine (CuTPMA). A suitable alkaline solution (e.g., NaOH solution) can be used to titrate the HEPES buffer solution, thereby allowing the reaction medium to have a pH value of about 6 to about 8, for example, about 7.2. An excitation current of about 20 mA can be applied to the cathode for about 0.5 minutes before applying a current of about 10 mA to the cathode. The nitrogen gas separation membrane of the nitrogen gas generation equipment 202 may be made of poly(4-methyl-1-pentene) and may have an average pore size of about 0.01 μm. The nitrogen gas generation equipment 202 can generate a carrier gas 122 containing N2 at a concentration of about 99.0% by volume from compressed air. The carrier gas 122 can be introduced into the sparger 134 at a flow rate of about 50 mL / min. The gas circulation circuit 300 can recirculate the product gas at a flow rate of about 0.5 L / min. After a ramp period of about 10 minutes from the application of current to the cathode, the NO generating system 100 can output a product gas with an NO concentration of about 200 ppm. After the application of current to the cathode is terminated, the liquid-gas separation circuit 400 can operate in a working mode for about 10 minutes and then in a cleaning mode for about 1 minute. The separation membrane of the liquid-gas separation device 408 has a resistance of about 25,000 cm 2 may have a surface area of

[0109] Alternatively, for example, the cathode and anode may be made of gold. The reaction medium may contain about 1 mol / L MOPS buffer, about 1 mol / L sodium nitrite, and about 3 mmol / L Fe-1,4,7-triazacyclononane. The MOPS buffer may be titrated using an appropriate alkaline solution (e.g., NaOH solution), resulting in a reaction medium having a pH value of about 6 to about 8, e.g., about 7.2. An excitation voltage of about 4.2 V may be applied to the cathode for about 1 minute before a voltage of about 1.4 V is applied to the cathode. The nitrogen gas separation membrane of the nitrogen gas generation equipment 202 may be made of brominated polycarbonate and may have an average pore size of about 0.02 μm. The nitrogen gas generation equipment 202 may generate a carrier gas 122 containing N2 at a concentration of about 99.6% by volume from compressed air. The carrier gas 122 can be introduced into the sparger 134 at a flow rate of about 100 mL / min. The gas circulation circuit 300 can recirculate the product gas at a flow rate of about 1 L / min. After a ramp period of about 9 minutes from applying voltage to the cathode, the NO generation equipment 100 can output product gas with an NO concentration of about 1200 ppm. After terminating the application of voltage to the cathode, the liquid-gas separation circuit 400 can operate in a working mode for about 5 minutes, and then in a cleaning mode for about 0.5 minutes. The separation membrane of the liquid-gas separation device 408 has a flow rate of about 1000 cm 2 may have a surface area of

[0110] Alternatively, for example, the cathode and anode may be made of carbon. The reaction medium may contain about 1.5 mol / L Tris buffer, about 2 mol / L potassium nitrite, and about 4 mmol / L Ti(Me3TACN). An appropriate alkaline solution (e.g., NaOH solution) may be used to titrate the Tris buffer, thereby causing the reaction medium to have a pH value of about 6 to about 8, for example, about 7.2. An excitation current of about 500 mA may be applied to the cathode for about 1.5 minutes before applying a current of about 100 mA to the cathode. The nitrogen gas separation membrane of the nitrogen gas generation equipment 202 may be made of polypropylene and may have an average pore size of about 0.012 μm. The nitrogen gas generation equipment 202 may generate a carrier gas 122 containing N2 at a concentration of about 99.7% by volume from compressed air. The carrier gas 122 may be introduced into the sparger 134 at a flow rate of about 200 mL / min. The gas circulation circuit 300 can recirculate the product gas at a flow rate of about 1.5 L / min. After a ramp period of about 6 minutes from applying current to the cathode, the NO generation equipment 100 can output product gas with an NO concentration of about 3000 ppm. After terminating the application of current to the cathode, the liquid-gas separation circuit 400 can operate in a working mode for about 12 minutes, and then in a cleaning mode for about 0.9 minutes. The separation membrane of the liquid-gas separation device 408 has a flow rate of about 1000 cm 2 from approximately 50,000 cm 2 surface area of, for example, about 50,000 cm 2 may have a surface area of

[0111] Alternatively, for example, the cathode and anode may be made of SiO2 coated with glassy carbon. The reaction medium may contain about 2 mol / L MOPS buffer, about 3 mol / L sodium nitrite, and about 5 mmol / L chromium tris(2-pyridylmethyl)amine (CrTPMA). An appropriate alkaline solution (e.g., NaOH solution) may be used to titrate the MOPS buffer, thereby allowing the reaction medium to have a pH value of about 6 to about 8, for example, about 7.2. An excitation voltage of about 12 V may be applied to the cathode for about 2 minutes before a voltage of about 2 V is applied to the cathode. The nitrogen gas separation membrane of the nitrogen gas generation equipment 202 may be made of polyimide and may have an average pore size of about 0.005 μm. The nitrogen gas generation equipment 202 may generate a carrier gas 122 containing N2 at a concentration of about 99.99% by volume from compressed air. The carrier gas 122 can be introduced into the sparger 134 at a flow rate of about 300 mL / min. The gas circulation circuit 300 can recirculate the product gas at a flow rate of about 2 L / min. After a ramp period of about 5 minutes from applying voltage to the cathode, the NO generation equipment 100 can output product gas with an NO concentration of about 4200 ppm. After terminating the application of voltage to the cathode, the liquid-gas separation circuit 400 can operate in a working mode for about 5 minutes, and then in a cleaning mode for about 1.5 minutes. The separation membrane of the liquid-gas separation device 408 has a flow rate of about 1000 cm 2 Approximately 5000cm from 2 surface area of, for example, about 37500 cm 2 may have a surface area of

[0112] Alternatively, for example, the cathode and anode may be made of conductive glass coated with stainless steel. The reaction medium may contain about 2.5 mol / L phosphate buffer, about 4 mol / L sodium nitrite, and about 6 mmol / L manganese-tris(2-pyridylmethyl)amine (MnTPMA). The phosphate buffer may be titrated using an appropriate alkaline solution (e.g., NaOH solution), resulting in a reaction medium having a pH value of about 6 to about 8, e.g., about 7.2. An excitation current of about 1.4 A may be applied to the cathode for about 2.5 minutes before applying a current of about 200 mA to the cathode. The nitrogen gas separation membrane of the nitrogen gas generation equipment 202 may be made of polydimethylsiloxane (PDMS) and may have an average pore size of about 0.008 μm. The nitrogen gas generation equipment 202 may generate a carrier gas 122 containing N2 at a concentration of about 99.8% by volume from compressed air. The carrier gas 122 can be introduced into the sparger 134 at a flow rate of about 400 mL / min. The gas circulation circuit 300 can recirculate the product gas at a flow rate of about 2.5 L / min. After a ramp period of about 4.6 minutes from applying current to the cathode, the NO generation system 100 can output product gas with an NO concentration of about 6300 ppm. After terminating the application of current to the cathode, the liquid-gas separation circuit 400 can operate in a working mode for about 20 minutes and then in a cleaning mode for about 2 minutes. The separation membrane of the liquid-gas separation device 408 has a flow rate of about 1000 cm 2 Approximately 5000cm from 2 surface area of, for example, about 12500 cm 2 may have a surface area of

[0113] Also, for example, the cathode and anode may be made of stainless steel coated with an iridium-ruthenium alloy. The reaction medium may include about 3 mol / L of boric acid-borax buffer solution, about 5 mol / L of potassium nitrite, and about 7 mmol / L of cobalt-(bis(2-aminoethylpropionyl)propionic acid). An appropriate alkaline solution (e.g., NaOH solution) may be used to titrate the boric acid-borax buffer solution, thereby allowing the reaction medium to have a pH value of about 6 to about 8, for example, a pH value of about 7.2. An excitation voltage of about 24 V may be applied to the cathode for about 3 minutes before a voltage of about 3 V is applied to the cathode. The nitrogen gas separation membrane of the nitrogen gas generation equipment 202 may be made of brominated polycarbonate and may have an average pore size of about 0.015 μm. The nitrogen gas generation equipment 202 includes: A carrier gas 122 containing N2 with a concentration of approximately 99.9% by volume can be generated from compressed air. The carrier gas 122 can be introduced into the sparger 134 at a flow rate of approximately 600 mL / min. The gas circulation circuit 300 can recirculate the product gas at a flow rate of approximately 3 L / min. After a ramp period of approximately 5 minutes from applying voltage to the cathode, the NO generation equipment 100 can output a product gas with an NO concentration of approximately 10,400 ppm. After terminating the application of current to the cathode, the liquid-gas separation circuit 400 can operate in a working mode for approximately 18 minutes and then in a cleaning mode for approximately 1.6 minutes. The separation membrane of the liquid-gas separation device 408 has a flow rate of approximately 1000 cm 2 Approximately 5000cm from 2 surface area of, for example, about 5000 cm 2 may have a surface area of

[0114] Product gas filtration System 10 may include one or more filtration systems or devices for reducing or removing one or more impurities in the product gas. In some embodiments, as shown in FIG. 1 , system 10 includes filtration system 500 downstream of NO production facility 100. For example, filtration system 500 may be downstream of and in fluid communication with gas region 110 and / or outlet circuit 124 of NO production facility 100. Filtration system 500 may reduce or remove one or more impurities, such as moisture and / or solid matter, in the product gas from NO production facility 100. As described herein, moisture may include any liquid, in either gas or liquid phase, that may be present in the product gas, such as water vapor, water droplets, solvent vapor, and solvent droplets.

[0115] The filtration system 500 may include one or more filtration devices or filters. In some embodiments, the filtration system 500 includes one or more solid material filters 502. It is contemplated that the solid material filters 502 may be configured to filter any type of solid material, for example, by modifying or selecting the filtration material and / or pore size. In one embodiment, the solid material filter 502 may be a salt aerosol filter. In some embodiments, the solid material filter 502 includes a membrane filter. The membrane filter may include a polymeric material having a porous structure. For example, the polymeric material may include one or more materials selected from polytetrafluoroethylene (PTFE), polyvinylidene fluoride, polyethersulfone, mixed cellulose esters, polyamide (nylon), nylon 6, and nylon 66. The average pore size of the porous structure can range from about 0.01 μm to about 2 μm, e.g., from about 0.1 μm to about 0.2 μm, from about 0.2 μm to about 0.4 μm, from about 0.4 μm to about 0.6 μm, from about 0.6 μm to about 0.8 μm, from about 0.8 μm to about 1.0 μm, from about 1.0 μm to about 1.2 μm, from about 1.2 μm to about 1.4 μm, from about 1.4 μm to about 1.6 μm, from about 1.6 μm to about 1.8 μm, from about 1.8 μm to about 2 μm, or a combination thereof.

[0116] In one example, the solid filter 502 may include a filter member made of PTFE and have an average pore size of about 1.0 μm. In another example, the solid filter 502 may include a filter member made of polyvinylidene fluoride and have an average pore size of about 0.1 μm. In another example, the solid filter 502 may include a filter member made of polyethersulfone and have an average pore size of about 2.0 μm. In another example, the solid filter 502 may include a filter member made of nylon 6 and have an average pore size of about 0.1 μm. In another example, the solid filter 502 may include a filter member made of nylon 66 and have an average pore size of about 0.8 μm. In another example, the solid filter 502 may include a filter member made of mixed cellulose esters and have an average pore size of about 1.6 μm.

[0117] In some embodiments, the filtration system 500 includes one or more moisture filters 504. 04. The moisture filter 504 can reduce or remove liquids, such as water, in the gas and / or liquid phase. In some embodiments, the moisture filter 504 includes a membrane filter. In some embodiments, the membrane filter includes a polymeric material. The polymeric material may have a porous structure. The polymeric material can absorb liquid vapor and / or liquid droplets. Additionally or alternatively, the polymeric material can be at least partially permeable to liquid vapor and / or liquid droplets. For example, the membrane filter may include a Nafion® membrane.

[0118] In some embodiments, filtration system 500 includes one or more additional filters 506. Filter 506 may be located downstream of solid material filter 502 and / or moisture filter 504 to further remove or reduce impurities, such as moisture and / or solid material, from the product gas. In some embodiments, filter 506 includes a membrane filter. In some embodiments, the membrane filter includes a polymeric material. In some embodiments, the membrane filter has a porous structure. For example, the polymeric material of the membrane filter may have a porous structure. The average pore size of the porous structure can range from about 0.01 μm to about 2 μm, e.g., from about 0.01 μm to about 0.1 μm, from about 0.1 μm to about 0.2 μm, from about 0.2 μm to about 0.3 μm, from about 0.3 μm to about 0.4 μm, from about 0.4 μm to about 0.5 μm, from about 0.5 μm to about 1.0 μm, from about 1.0 μm to about 2 μm, or combinations thereof. In some embodiments, the average pore size of filter 506 is equal to or smaller than the average pore size of solid material filter 502.

[0119] As described herein, the membrane filter used in some embodiments of the present disclosure may include at least one membrane layer, which may have any suitable configuration for filtering or separating gases, liquids, and / or solids. For example, the membrane of the membrane filter may be configured for dead-end filtration, in which a fluid can pass through the membrane and components to be separated from the fluid can be intercepted or captured by the membrane. Alternatively, the membrane of the membrane filter may be configured for cross-flow filtration, in which a fluid can pass over the surface of the membrane on the feed side and components to be separated from the fluid can be retained on the feed side or permeate through the membrane to the permeate side. An exemplary configuration for cross-flow filtration is one or more hollow fibers formed from the membrane.

[0120] For example, the product gas output from the gas region 110 of the NO production facility 100 may contain a certain amount of liquid and / or solid impurities, such as water and salt aerosols. Such amounts of impurities can damage and / or affect the lifespan of downstream equipment, such as the pump 306 and one or more of the filters 502-506. In some embodiments, the system 500 includes a filtration device 508 located downstream of the NO production facility 100. In some embodiments, the filtration device 508 is located upstream of the pump 306 to reduce or remove liquid and / or solid impurities in the recirculating product gas 303. For example, the product gas output from the gas region 110 of the NO production facility 100 may contain one or more impurities, such as water or droplets or vapor of the reaction medium 112. In some embodiments, the filtration device 508 is located upstream of the solid material filter 502 and / or the moisture filter 504. Filtration device 508 may reduce or remove liquid and / or solid impurities from the product gas before the product gas flows through one or more of filters 502-506.

[0121] 5A-5C illustrate a filtration device 508 according to some embodiments of the present disclosure. As shown in FIGS. 5A-5C, in some embodiments, the filtration device 508 includes a housing 510, an inlet 518, and an outlet 520. In some embodiments, the filtration device 508 includes at least one chamber disposed within the housing 510. The inlet 518 and / or the outlet 520 may be in fluid communication with the at least one chamber within the housing 510. The housing 510 may have any suitable shape, for example, a cylindrical shape. As shown in FIG. 5C, the inlet 518 may be disposed at a bottom portion of the housing 510 and in fluid communication with the chamber. The outlet 520 may be disposed at a top portion of the housing 510 and in fluid communication with the chamber.

[0122] 5B, the filtration device 508 includes one or more filtration chambers 512. The filtration chambers 512 may have any suitable shape, such as a cylindrical shape. The filtration chambers 512 may be arranged around the longitudinal axis of the housing 510 and may be equally or unevenly spaced apart. The filtration device 508 may include any suitable number of filtration chambers 512, such as two to five filtration chambers. For example, three filtration chambers 512 may be equally spaced about the longitudinal axis of the housing 510, spaced approximately 120 degrees apart.

[0123] Each filtration chamber 512 may have an inlet 522 and an outlet 524. The inlet and outlet of one or more filtration chambers 512 may define a flow path. One or more filtration chambers 512 (e.g., the first filtration chamber 512) may have an inlet 522 fluidly connected to an inlet 518 of the housing 510. One or more filtration chambers 512 (e.g., the last filtration chamber 512) may have an outlet 524 fluidly connected to an outlet 520 of the housing 510. In some embodiments, the filtration chambers 512 include a filtration material 516 configured to reduce or remove one or more impurities from a fluid flowing therethrough. The filtration material 516 may fill at least a portion of the filtration chamber 512, such as a central portion of the filtration chamber 512. The filtration material 516 may include any suitable material, such as silica gel, sponge, cotton, polypropylene (e.g., a PP cotton filter), foam, and expanded resin.

[0124] In some embodiments, the filtration device 508 includes a feed chamber 526. The feed chamber 526 may be in fluid communication with the inlet 518 and is used to receive a fluid, such as a gas flow, to be filtered. The feed chamber 526 may be in fluid communication with one or more filtration chambers 512. For example, the feed chamber 526 may have an outlet that is in fluid communication with the inlet 522 of the filtration chamber 512. In some embodiments, the feed chamber 526 extends through a middle portion of the housing 510, thereby forming a cavity between the feed chamber 526 and the interior surface of the housing 510.

[0125] For example, as shown in Figures 5A-5C, the housing 510 may have a cylindrical shape. The feed chamber 526 may have a cylindrical shape extending along at least a portion of the longitudinal axis of the housing 510. The annular space formed between the feed chamber 526 and the housing 510 may form a cavity. In some embodiments, one or more chambers (e.g., the filtration chamber 512) are disposed in the cavity between the feed chamber 526 and the housing 510.

[0126] Filtration device 508 may be configured to allow at least some liquid and / or solid impurities in the gas (e.g., product gas output from gas region 110) to separate from the gas, for example, based on gravitational settling or separation. In some embodiments, inlet 522 of filtration chamber 512 is positioned vertically lower than outlet 524, allowing liquid and / or solid particles suspended in the gas flowing from inlet 522 to outlet 524 to settle out of the gas and to the bottom of filtration chamber 512.

[0127] For example, the filtration chamber 512 may have an elongated shape (e.g., a cylindrical shape), and The filtration chamber 512 may be disposed vertically along the longitudinal axis of the filtration material 516. In such a configuration, the inlet 522 may be disposed at a bottom or lower portion of the filtration chamber 512, and the outlet 524 may be disposed at a top or upper portion of the filtration chamber 512. The gas flow may enter the filtration chamber 512 at the inlet 522, move or rise through at least a portion of the filtration chamber 512, and reach the outlet 524. As the gas flow moves or rises in the filtration chamber 512, the gas flow may pass through the filtration material 516, and liquid and / or solid impurities suspended in the gas flow may settle out and separate from the gas flow.

[0128] In some embodiments, the filtration device 508 includes a buffer chamber 514 in fluid communication with the filtration chamber 512. For example, the buffer chamber 514 may be fluidly connected to the filtration chamber 512 via an opening or port in a bottom portion of the filtration chamber 512. The gas to be filtered (e.g., the gas flow) may flow from the buffer chamber 514 to the filtration chamber 512 via the opening or port, rise in the filtration chamber 512, and be discharged through the outlet 524. Liquid and / or solid matter that settles out of the gas in the filtration chamber 512 may settle in the bottom portion of the filtration chamber 512. The settled liquid and / or solids may flow to and accumulate in the buffer chamber 514.

[0129] The liquid and / or solid materials accumulated in the buffer chamber 514 can be pumped out of the filtration device 508 by any suitable means (e.g., gravity or a pump). The liquid and / or solid materials pumped out of the filtration device 508 can be disposed of or reused. For example, the reaction medium 112 that settles out of the product gas from the NO production facility 100 can be pumped from the buffer chamber 514 back into the liquid region 108 of the reaction chamber 102 for repeated use.

[0130] 5C, buffer chamber 514 is in fluid communication with feed chamber 526. Fluid can flow from feed chamber 526 to buffer chamber 514 and from buffer chamber 514 to filtration chamber 512. For example, a fluid to be filtered (e.g., a gas flow) can flow from inlet 518 through feed chamber 526, buffer chamber 514, and filtration chamber 512 to outlet 520.

[0131] 5A-5C, the filtration device 508 includes two or more fluidly connected filtration chambers 512 to allow more than one settling process to proceed. For example, the outlet 524 of a first filtration chamber 512 may be fluidly connected to the inlet 522 of a second filtration chamber 512. Gas can flow through the two or more filtration chambers 512 to allow liquid and / or solid impurities to rise with the gas flow from the inlet 522 to the outlet 524 of each filtration chamber and settle out of the gas flow.

[0132] In some embodiments, as shown in FIGS. 5A-5B, the buffer chamber 514 fluidly connects two filtration chambers 512. The buffer chamber 514 may have an opening or conduit configured to connect the two filtration chambers 512, allowing fluid to flow from the inlet 522 to the outlet 524 of each of the two filtration chambers 512. For example, as shown in FIG. 5B, the outlet 524 of the first filtration chamber 512 may be the inlet of the buffer chamber 514, and the inlet 522 of the second filtration chamber 512 may be the outlet of the buffer chamber 514. Fluid may flow from the outlet 524 of the first filtration chamber 512 to the buffer chamber 514 and from the buffer chamber 514 to the inlet 522 of the second filtration chamber 512. In such a case, the outlet 524 of the first filtration chamber 512 may be located at the top portion of the buffer chamber 514, and the inlet 522 of the second filtration chamber 512 may be located at the bottom portion of the buffer chamber 514, as shown in FIG. 5B.

[0133] The filtering device 508 may include one or more other components, such as components for covering or sealing one or more inlets, outlets, and / or chambers in the housing 510. In some embodiments, as shown in FIG. 5A, the filtering device 508 may include a buffer chamber 516. 5A , filtration device 508 includes a seal configured to coat a top side of buffer chamber 514 to allow gas in inlet 514 to flow from buffer chamber 514 to one or more filtration chambers 512. In some embodiments, as shown in FIG. 5A , filtration device 508 includes a coating 528. Coating 528 can coat a top side of housing 510 and can coat a top side of filtration chamber 512 to allow gas in filtration chamber 512 to exit at outlet 524. Coating 528 can be secured to housing 510 via any suitable connection, such as a press fit or by use of suitable fastening components (e.g., threaded fasteners). In some embodiments, as shown in FIG. 5A , filtration device 508 includes a seal ring configured to form a seal around inlet 518.

[0134] pressure vessel The flow rate and / or NO concentration of the product gas produced by NO generation facility 100 can vary due to changes in one or more conditions, such as temperature, current or voltage applied to the electrodes, side reactions, electrode degradation, or changes in the nitrite source and catalyst concentration in reaction medium 112. System 10 may include one or more devices or systems (e.g., pressure vessels) for stabilizing the flow rate and / or NO concentration of the product gas produced by NO generation facility 100. Such devices or systems can allow system 10 to provide a stable supply of NO.

[0135] 1 , system 10 includes pressure vessel 600. Pressure vessel 600 may be located downstream of and fluidly connected to NO generation facility 100. In some embodiments, pressure vessel 600 receives product gas from outlet circuit 124 of NO generation facility 100. One or more filters of filtration system 500 may be located downstream of NO generation facility 100 and upstream of pressure vessel 600. Product gas from NO generation facility 100 may flow from outlet circuit 124 through one or more filters of filtration system 500 to pressure vessel 600. Before the product gas enters pressure vessel 600, filtration system 500 may reduce or remove one or more impurities in the product gas, such as moisture and / or solid matter (e.g., salt aerosols).

[0136] In some embodiments, as shown in FIG. 6A , pressure vessel 600 includes a body 602, a gas inlet 612, and a gas outlet 614. Body 602 may have any suitable shape, such as a cylindrical shape, configured to enclose an interior cavity. Gas inlet 612 and gas outlet 614 are fluidly connected to the interior cavity of body 602. For example, as shown in FIG. 6A , gas inlet 612 and / or gas outlet 614 may each comprise an opening or port disposed in body 602.

[0137] The pressure vessel 600 may receive and store product gas from the NO generation system 100 during a pressure hold period. At the end of the pressure hold period, the pressure within the pressure vessel 600 may increase to a preset level or a preset range. Additionally or alternatively, at the end of the pressure hold period, the concentration of NO in the product gas contained in the pressure vessel 600 may increase to a preset level or a preset range. The pressure hold period may be predetermined and / or adjusted. In some embodiments, the product gas may be released from the pressure vessel 600 after the pressure hold period. The NO concentration of the product gas released from the pressure vessel 600 may increase within a ramp period and reach a steady state at or after the end of the ramp period.

[0138] In some embodiments, pressure vessel 600 is configured to shorten the pressure hold and ramp periods to allow for faster or immediate provision of a stable NO supply. For example, pressure vessel 600 may include one or more flow channels in the interior cavity of body 602. The one or more flow paths may include a serpentine flow path. The one or more flow paths may include a tortuous flow path, e.g., a serpentine flow path. The one or more flow paths may allow the pressure and / or NO concentration of the product gas within at least a portion of the internal cavity of the body 602 to quickly reach a steady state. For example, the one or more flow paths may allow new gas (e.g., product gas) to enter the internal cavity and quickly purge or consume old gas (e.g., air or nitrogen gas) previously present in at least a portion of the internal cavity. Additionally or alternatively, the one or more flow paths may reduce or eliminate non-uniform mixing of the new gas and the old gas.

[0139] As described herein, a tortuous flow path (e.g., a serpentine flow path) may refer to a non-direct flow path that extends from a first point to a second point along any direction in three-dimensional space. For example, a tortuous flow path may refer to a non-direct flow path that extends from a first point to a second point in a transverse and / or longitudinal plane through pressure vessel 600.

[0140] For example, pressure vessel 600 can permit a pressure hold period of less than about 60 minutes, e.g., less than about 1 minute, less than about 5 minutes, less than about 10 minutes, less than about 20 minutes, less than about 30 minutes, less than about 40 minutes, or less than about 50 minutes. For example, pressure vessel 600 can permit a ramp period of less than about 20 minutes, e.g., less than about 1 minute, less than about 2 minutes, less than about 3 minutes, less than about 4 minutes, less than about 5 minutes, less than about 8 minutes, or less than about 10 minutes.

[0141] 6A-6C illustrate various views of a pressure vessel 600 according to some embodiments of the present disclosure. In some embodiments, the pressure vessel 600 includes one or more panels or baffles 604 that define multiple fluidly connected regions in the interior cavity. In various configurations, the fluidly connected regions can form a tortuous flow path, e.g., a serpentine flow path, through the pressure vessel 600. For example, the multiple panels 604 can partition the interior cavity into a first region 606 and a second region 608. The first region 606 and the second region 608 can be fluidly connected via, for example, an opening, a port, or a conduit. A fluid (e.g., product gas) entering the pressure vessel 600 can enter the first region 606 and flow from the first region 606 to the second region 608 via the tortuous flow path. Alternatively, fluid (e.g., product gas) entering pressure vessel 600 can enter first region 606 and leave the pressure vessel without entering or flowing through second region 608, i.e., bypassing second region 608. A tortuous flow path can allow new gas entering pressure vessel 600 to effectively purge or consume old gas previously present in the pressure vessel. A tortuous flow path can also allow the pressure in one or more regions of pressure vessel 600 to reach a steady state within a shorter period of time than is required to allow the pressure in the entire pressure vessel to reach a steady state.

[0142] In some embodiments, first region 606 is fluidly connected to a gas inlet 612 and a gas outlet 614. For example, gas inlet 612 may be fluidly connected to a first opening or a first port provided in first region 606. Gas outlet 614 may be fluidly connected to a second opening or a second port provided in first region 606. Gas may flow from gas inlet 612 to gas outlet 614 through at least a portion of first region 606.

[0143] The first region 606 may be configured to allow gas entering the gas inlet 612 to quickly fill at least a portion of the first region 606. In some embodiments, the first region 606 is divided into multiple chambers that define a first flow path 618. For example, one or more panels 616 may be provided in the first region 606 to divide the first region into multiple chambers. The first flow path 618 may be a tortuous flow path, such as a serpentine flow path. A tortuous flow path can allow new gas entering the first region 606 to quickly purge or consume old gas previously present in one or more chambers of the first region 606. This can allow the pressure in one or more chambers of the first region 606 to reach a steady state within a shorter period of time than is required to allow the pressure in one or more chambers in the first region 606 and the second region 608 to reach a steady state. For example, it may take less than about 5 minutes for one or more chambers of the first region 606 to reach a steady pressure, while it may take about 20 to about 30 minutes for the internal cavity of the body 602 of the pressure vessel 600 to reach a steady pressure.

[0144] 6B and 6C, the gas inlet 612 and the gas outlet 614 may be fluidly connected to the first chamber 606a. Product gas may flow from the gas inlet 612 to the gas outlet 614 through at least a portion of the first chamber 606a. The product gas received at the gas inlet 612 may enter the first chamber 606a of the first region 606 and quickly fill the first chamber 606a of the first region 606, thereby allowing the pressure in the first chamber 606a to reach a steady state within a short period of time. This may reduce the pressure hold time before releasing the product gas from the gas outlet 614.

[0145] The first chamber 606a may have any suitable shape and / or size that allows the pressure of the product gas therein to reach a steady state within a short pressure hold period. For example, the first chamber 606a may have an elongated shape and a narrow cross-section extending along the longitudinal dimension of the body 602. The first chamber 606a may have any suitable size or volume. For example, the volume of the first chamber 606a may be 50% or less of the volume of the interior cavity of the body 602. For example, the pressure vessel 600 may have an internal volume of approximately 800 mL, and the first chamber 606a may have a volume of approximately 10 mL to approximately 200 mL. In one example, after a pressure hold period in which the pressure vessel 600 receives and holds product gas for approximately 20 minutes, the pressure vessel 600 may release the product gas at the gas outlet 614, and the NO concentration in the released product gas may reach a steady state within approximately 10 minutes.

[0146] In some embodiments, the second region 608 is fluidly connected to the first region 606 via a passageway 610. The second region 608 can receive and store gas escaping from the first region 606. The second region 608 can include a tortuous flow path, such as a serpentine flow path. For example, the second region 608 can be configured to allow gas from the first region 606 to fill at least a portion of the second region 608.

[0147] In some embodiments, the second region 608 is divided into multiple chambers that define a second flow path 620. For example, one or more panels 616 may be provided in the second region 616 to divide the second region into multiple chambers. The second flow path 620 may be fluidly connected to the first flow path 618, for example, via the passageway 610. The second flow path 620 and the first flow path 618 may form a continuous flow path. The second flow path 620 may be a tortuous flow path, for example, a serpentine flow path. A tortuous flow path can allow new gas entering the second region 608 from the first region 606 to purge or consume old gas previously present in one or more chambers of the second region 608. This can further allow the pressure in one or more chambers of the second region 608 to reach a steady state before the pressure in the entire second region 608 reaches a steady state.

[0148] The chambers of the second region 608 may be referred to as gas storage units. One or more of the chambers of the second region 608 may be gas storage units. The second region 608 may be further divided into one or more subchambers to further reduce the volume. This can reduce or eliminate uneven mixing of new and old gas in the second region 608 and can reduce the time required for the pressure in the second region 608 to reach a steady state. For example, each chamber in the second region 608 may be divided into two or more fluidly connected subchambers by one or more dividers 609. The dividers 609 may have any suitable structure, such as a panel or plate, for guiding gas flow in the chamber. For example, as shown in FIGS. 6B and 6C , two or more dividers 609 may each extend along at least a portion of the longitudinal axis of the pressure vessel 600 and may be radially spaced apart such that the subchambers are fluidly connected via spaces 611 between the dividers.

[0149] As described herein, the fluidly connected chambers in the first region 606 or the second region 608 may have any suitable configuration for defining a flow path that allows new gas to purge or consume pre-existing old gas in one or more chambers of the region. For example, as shown in FIG. 6C , the inlet and outlet of a chamber (e.g., the first chamber 606a) may be spaced apart along at least one dimension (e.g., the horizontal and / or vertical dimension). Such a configuration can allow new gas entering the chamber to flow from the inlet through the chamber along at least one dimension to the outlet, purging or consuming pre-existing old gas in the chamber.

[0150] The second region 608 can be used as a reservoir for storing product gas. For example, if the flow rate of product gas received at the gas inlet 612 is higher than the flow rate of product gas released at the gas outlet 614, the excess product gas can flow from the first region 606 to the second region 608 for storage. If the flow rate of product gas received at the gas inlet 612 is lower than the flow rate of product gas released at the gas outlet 614, the product gas stored in the second region 608 can flow from the second region 608 to the first region 606 to replenish the product gas flow. In such a case, the pressure vessel 600 can reduce variations in the pressure, flow rate, and / or NO concentration of the product gas released at the gas outlet 614. This can be advantageous, for example, in providing a stable NO supply when NO production can vary due to various conditions. This can further be advantageous in providing an NO supply at a desired pressure, flow rate, and / or concentration as needed. The second region 608 can also be used as a backup source of NO. For example, in response to an anomaly in the production of NO by NO generating facility 100 and / or the delivery of NO through system 10, product gas stored in second region 608 may be released to continue or replenish the supply of NO.

[0151] In some embodiments, pressure vessel 600 includes a pressure relief valve 622. The pressure relief valve 622 is configured to control the pressure within pressure vessel 600 so that it does not exceed a threshold value. The threshold value may be a preset safety threshold. The pressure relief valve 622 may be normally closed, for example, by spring force. When the pressure within one or more regions of pressure vessel 600 exceeds a threshold value, the pressure relief valve 622 can be opened. In some embodiments, the pressure relief valve 622 is in fluid communication with second region 608. As shown in FIG. 1 , product gas released from the pressure relief valve 622 can be transported from pressure vessel 600 to an exhaust gas treatment system 700.

[0152] In some embodiments, system 10 includes one or more pressure sensors for measuring pressure in one or more regions or chambers in pressure vessel 600. In some embodiments, pressure sensor 624 may be configured to measure the pressure in first region 606, e.g., the pressure in first chamber 606a of first region 606. The measurement of pressure sensor 624 can be indicative of the pressure of the product gas released from gas outlet 614 to a downstream system or apparatus. In some embodiments, one or more pressure sensors (not shown) may be configured to measure the pressure in second region 608. The measurement of such a pressure sensor can be indicative of the amount of product gas stored in second region 608.

[0153] In some embodiments, pressure vessel 600 includes a purge valve 626. Purge valve 626 can be used to purge or exhaust gas, such as product gas, in one or more regions of the interior cavity of pressure vessel 600. For example, purge valve 626 can be in fluid communication with first region 606 or second region 608. As shown in FIG. 1 , product gas released from purge valve 626 can be transported from pressure vessel 600 to exhaust gas treatment device 700. In some embodiments, as shown in FIG. 1 , NO sensor 628 is located downstream of purge valve 626 and configured to measure the NO concentration of the product gas released from purge valve 626. The measurement of NO sensor 628 can indicate whether product gas has been purged or exhausted from one or more regions of pressure vessel 600.

[0154] 1 , system 10 includes one or more flow control devices 630 for controlling the flow rate of product gas released from pressure vessel 600. Flow control device 630 may be located downstream of and in fluid communication with gas outlet 614. Flow control device 630 may include a flow meter and / or a flow controller, e.g., a flow control valve. In some embodiments, system 10 includes a first flow control device 630 and a second flow control device 630. First flow control device 630 may be selected to measure and / or adjust a flow rate within a first range, and second flow control device 630 may be selected to measure and / or adjust a flow rate within a second range that is lower than the first range. As described below, flow control device 630 may be in communication with and / or controlled by one or more other components of system 10 (e.g., vent circuit 900).

[0155] Waste Gas Treatment System 10 may generate waste gas before, during, and / or after producing and / or delivering NO. For example, waste gas may be generated during the process of separating NO from reaction medium 112 by liquid-gas separator 408. Also, waste gas may be generated, for example, when releasing product gas through pressure relief valve 622 of pressure vessel 600. The waste gas from system 10 may contain one or more components, such as NO, carrier gas, moisture, and other nitrogen oxides that may be generated during the process of producing and / or delivering NO. For example, during the process of producing or delivering NO in system 10, NO can be oxidized to nitrogen dioxide (NO).

[0156] Nitrogen oxides (NO x Nitrogen oxides (also referred to as nitrogen oxides), such as NO and NO, can pose air pollution and / or health risks if released directly into the environment from system 10. In some embodiments, as shown in FIG. 1, system 10 includes one or more waste gas treatment devices 700 for treating the waste gases before releasing them from system 10. Waste gas treatment devices 700 can reduce or eliminate potential air pollution and / or exposure to nitrogen oxides by reducing or removing one or more types of nitrogen oxides in the waste gases.

[0157] In some embodiments, the waste gas treatment device 700 is located downstream of and in fluid communication with the liquid-gas separation device 408. The waste gas treatment device 700 can receive a mixed gas from the outlet 426 of the liquid-gas separation device 408. The mixed gas may include a sweep gas and one or more nitrogen oxides (e.g., NO and NO2). In some embodiments, the waste gas treatment device 700 is located downstream of the pressure vessel 600 and in fluid communication with the pressure relief valve 622. When the pressure in the pressure vessel 600 reaches or exceeds a threshold pressure, the waste gas treatment device 700 can receive a product gas that is released from the pressure relief valve 622. The product gas may include a carrier gas and one or more nitrogen oxides (e.g., NO and NO2).

[0158] In some embodiments, the waste gases from the pressure vessel 600 and the liquid-gas separator 408 can be treated by the same waste gas treatment device 700. For example, the system 10 can include a three-way connector 702 located upstream of the waste gas treatment device 700 and downstream of the pressure vessel 600 and the liquid-gas separator 408. The waste gases from the pressure vessel 600 and the liquid-gas separator 408 can be combined at the three-way connector 702 and flow to the same waste gas treatment device 700. The three-way connector 702 can include any suitable structure, such as a three-way fitting or a three-way valve.

[0159] In some embodiments, exhaust gas treatment device 700 reduces or removes one or more nitrogen oxides in the exhaust gas as the exhaust gas passes through it. In some embodiments, exhaust gas treatment device 700 includes a body, an inlet, and an outlet. The inlet and outlet are in fluid communication with a cavity defined by the body. In some embodiments, at least a portion of the cavity is filled with a filtration material that can reduce or remove one or more nitrogen oxides as the exhaust gas passes through the filtration material. For example, the filtration material can filter one or more nitrogen oxides, NO , and / or NO . x The filter may include one or more absorbent materials configured to absorb NO and NO2.

[0160] In some embodiments, the absorbent material includes a substrate prepared with an absorbent capable of reacting with one or more nitrogen oxides. For example, the substrate may be coated with an oxidizing agent. The substrate may have any suitable configuration for providing a surface area for the absorbent to react with one or more nitrogen oxides. For example, the substrate may include one or more materials selected from molecular sieves, silica gel, alumina, sponge, cotton, foamed resin, silicon dioxide, and activated carbon. For example, the absorbent may include one or more materials selected from permanganates, persulfates, chromates, and dichromates.

[0161] In some embodiments, the exhaust gas treatment device 700 includes a plurality of baffles configured to define a fluid path. In some embodiments, at least a portion of the flow path is filled with a filtration material. The flow path may be a tortuous flow path, such as a serpentine flow path. For example, a plurality of baffles may extend from a wall of the cavity in a staggered manner to define the tortuous flow path. The tortuous flow path may extend along one or more dimensions. The tortuous flow path may increase contact between the exhaust gas and the filtration material to allow for more nitrogen oxide reduction or removal as the exhaust gas passes through the device.

[0162] 7A-7C are various views of an exhaust gas treatment device 700 according to some embodiments of the present disclosure. As shown in FIGS. 7A-7C, in some embodiments, the exhaust gas treatment device 700 includes a body 703, an inlet 722, and an outlet 724. The inlet 722 and the outlet 724 are in fluid communication with a cavity 706 defined by the body 703. The body 703 may have any suitable shape, configuration, and / or size. For example, the body 703 may have a cylindrical shape.

[0163] In some embodiments, the body 703 has a first side 718 and a second side 720. The inlet 722 and the outlet 724 may be located on opposite sides of the body 703 or on the same side. For example, the inlet 722 may be located on the first side 718 and the outlet 724 may be located on the second side 720. Alternatively, the inlet 722 and the outlet 724 may both be located on the first side 718 or the second side 720. 0. In some embodiments, body 703 includes an inner shell 708 and an outer shell 710 extending from a first side 718 to a second side 720. Inner shell 708 and outer shell 710 can define an annular cavity 706. Inner shell 708 and outer shell 710 can have any suitable size. For example, outer shell 710 can have a diameter range of 120 mm to 160 mm, and inner shell 708 can have a diameter range of 80 mm to 120 mm.

[0164] 7C , the cavity 706 is bounded by a wall 716 that extends between the inner shell 708 and the outer shell 710 and from a first side 718 to a second side 720. An inlet 722 and an outlet 724 may be located near opposite sides of the wall 716. At least a portion of the cavity 706 may be filled with a filtration material (not shown). Waste gas that has passed through the waste gas treatment device 700 may flow from the inlet 722, through the cavity 706, and to the outlet 724.

[0165] In some embodiments, the exhaust gas treatment device 700 includes a plurality of baffles. The plurality of baffles may have any configuration that defines a tortuous flow path 704 (e.g., a serpentine flow path) in the cavity 706. In some embodiments, as shown in FIG. 7C , a first group of baffles 712 may extend between a first side 718 and a second side 720 and from the inner shell 708 toward the outer shell 710, and a second group of baffles 714 may extend between the first side 718 and the second side 720 and from the outer shell 710 toward the inner shell 708. The baffles 712 and 714 may extend any suitable distance between the inner shell 708 and the outer shell 710 to guide the exhaust gas flow. For example, the distance between the baffles 712 and the outer shell 710 and / or the distance between the baffles 714 and the inner shell 708 may be in the range of 2 mm to 8 mm.

[0166] In some embodiments, the first group of baffles 712 and the second group of baffles 714 may be arranged in a staggered manner. For example, as shown in FIG. 7C , the first group of baffles 712 may be uniformly distributed around the circumference of the inner shell 708, and the second group of baffles 714 may be uniformly distributed around the circumference of the outer shell 710, with the second group of baffles offset from the first group of baffles 712. The exhaust gas treatment device 700 may include any suitable number of baffles, e.g., from 2 to 16 baffles. For example, the number of first group of baffles 712 and / or second group of baffles 714 may be in the range of 2 to 8. The number of first group of baffles 712 and second group of baffles 714 may be the same or different. It is contemplated that the exhaust gas treatment device 700 may include any suitable number of baffles, which may or may not be provided with a suitable filtration material.

[0167] The waste gas may flow from an inlet 722 through a serpentine flow path 704 to an outlet 724. The serpentine flow path 704 may be filled with a filtration material. As the waste gas passes through the filtration material in the flow path 704, one or more nitrogen oxides in the waste gas may be absorbed. The waste gas may leave the waste gas treatment device 700 through the outlet 724 and may be released to the environment with or without further treatment.

[0168] Reduction and / or elimination of toxic nitrogen oxides NO can be oxidized to one or more toxic nitrogen oxides (e.g., NO), which can pose a health risk if transported to a patient along with NO. In some embodiments, system 10 includes a gas converter 800. Gas converter 800 converts the NO present in the product gas as it passes through the gas converter. The gas converter 800 can convert some or all of the potentially toxic nitrogen oxides (e.g., NO) that may be present in the product gas into NO. The gas converter 800 can reduce the potential risk of exposure to toxic nitrogen oxides and can increase NO production by converting other nitrogen oxides in the product gas back to NO.

[0169] In some embodiments, gas converter 800 is located downstream of and fluidly connected to NO generation equipment 100. In some embodiments, gas converter 800 is located downstream of and fluidly connected to filtration system 500. In some embodiments, gas converter 800 is located downstream of and fluidly connected to pressure vessel 600. FIG. 8A is an exploded view of a gas converter according to some embodiments of the present disclosure. In some embodiments, as shown in FIG. 8A , gas converter 800 includes a body 808, an inlet 818, and an outlet 820. Inlet 818 and outlet 820 are fluidly connected to a cavity defined by body 808. Body 808 may have any suitable shape. In some embodiments, body 808 has a cylindrical shape extending between a first side and a second side. Two end caps 806 may cover the first and second sides of body 808. The inlet 818 and outlet 820 may be located in the same end cap 806 or in different end caps 806 .

[0170] In some embodiments, gas converter 800 includes one or more membrane filters 810 and a filter holder 812. Filter holder 812 may be configured to mount membrane filter 810 between end cap 806 and body 808. Membrane filter 810 may reduce or remove one or more types of impurities, such as moisture and solid matter, in the product gas entering and / or leaving gas converter 800.

[0171] In some embodiments, at least a portion of the cavity is filled with a filtration material that can absorb one or more toxic nitrogen oxides, such as NO2, as the product gas passes through the filtration material. For example, the filtration material can include soda lime particles. In some embodiments, at least a portion of the cavity is filled with a filtration material that can convert one or more toxic nitrogen oxides (e.g., NO2) to NO as the product gas passes through the filtration material. In some embodiments, the filtration material includes a substrate configured to carry a reducing agent. For example, the surface of the substrate can be prepared, e.g., applied, treated, or coated, with a reducing agent. The reducing agent can react with one or more nitrogen oxides to reduce them to NO. The substrate can have any suitable configuration for providing a surface area for the reducing agent. For example, the substrate can include one or more materials selected from molecular sieves, silica gel, alumina, sponge, cotton, and foamed resin. For example, the reducing agent may include one or more antioxidants, such as vitamin A, vitamin E, and vitamin C. As used herein, vitamin C may also be referred to as ascorbic acid or ascorbate.

[0172] Any suitable method or process can be used to prepare the filtration material. For example, a certain amount of one or more reducing agents can be prepared in solution. The solution can be an aqueous solution or an organic solution, and the solution can be a saturated solution of one or more reducing agents. A certain amount of substrate can be added to the solution and mixed uniformly. The substrate can then be removed from the solution and dried at a drying temperature for a certain period of time to allow the solvent to evaporate. Any suitable amount of reducing agent and substrate can be selected based on one or more conditions, for example, the type of material used and the required reducing capacity. For example, a substrate with a quantity of about 100 g per substrate can be prepared using an amount of reducing agent ranging from about 5 g to about 50 g.

[0173] In one example, about 25 g of vitamin C can be used to coat about 100 g of alumina particles per alumina particle. In another example, about 5 g of vitamin A can be used to prepare about 100 g of cotton per cotton. In another example, about 5 g of vitamin E can be used to prepare about 100 g of foamed resin per foamed resin. In another example, about 30 g of vitamin C can be used to prepare about 100 g of molecular sieve per molecular sieve. In another example, about 20 g of vitamin A can be used to prepare about 100 g of sponge material per sponge material. In another example, about 15 g of vitamin E can be used to prepare about 100 g of silica gel per silica gel.

[0174] The drying temperature can range from about 40°C to about 150°C, e.g., from about 40°C to about 50°C, from about 50°C to about 60°C, from about 60°C to about 70°C, from about 70°C to about 80°C, from about 80°C to about 90°C, from about 90°C to about 100°C, from about 100°C to about 110°C, from about 110°C to about 120°C, from about 120°C to about 130°C, from about 130°C to about 140°C, from about 140°C to about 150°C, or a combination thereof. The drying time may range from about 0.1 h to about 10 h, e.g., from about 0.1 h to about 0.2 h, from about 0.2 h to about 0.5 h, from about 0.5 h to about 1 h, from about 1 h to about 2 h, from about 2 h to about 3 h, from about 3 h to about 4 h, from about 4 h to about 5 h, from about 5 h to about 6 h, from about 6 h to about 7 h, from about 7 h to about 8 h, from about 8 h to about 9 h, from about 9 h to about 10 h, or a combination thereof.

[0175] In some embodiments, as shown in FIGS. 8A-8B , the cavity of gas converter 800 is partitioned into multiple chambers 816, each having an inlet and an outlet. The inlet of the first chamber may be fluidly connected to inlet 818, and the outlet of the last chamber may be fluidly connected to outlet 820. The inlets and outlets of chambers 816 may be fluidly connected to define flow path 802. A filtration material may fill at least a portion of each chamber, for example, from the inlet to the outlet of the chamber. The inlet and outlet of each chamber may be located at opposite ends, allowing gas passing through the chamber to flow from the inlet, through the chamber, through the filtration material, and to the outlet.

[0176] Flow path 802 may be a tortuous flow path, such as a serpentine flow path. A tortuous flow path in the cavity of body 808 can increase contact between the product gas and the filtration material to allow more nitrogen oxides to be reduced to NO as the product gas passes through the device for a given cavity volume.

[0177] The chambers in the cavity of the gas converter 800 may have any suitable configuration. For example, one or more panels 814 may be provided on opposite sides of the body 808 and extend therebetween. The panels 814 may be equally or unevenly spaced about the longitudinal axis of the body 808. The panels 814 may each extend radially from the longitudinal axis to the interior wall of the body 808. For example, the panels 814 may uniformly divide the cavity into multiple elongated chambers 816 extending between opposite sides of the body 808 and disposed about the longitudinal axis of the body 808. Any suitable number of panels 814 may be used. For example, if the panels 814 are disposed about the longitudinal axis of the body 808, an odd number of panels 814 may divide the cavity into an odd number of chambers, and the inlets 818 and outlets 820 may be provided on opposing end caps 806. Alternatively, an even number of panels 814 may divide the cavity into an even number of chambers, and the inlets 818 and outlets 820 may be provided in the same end cap 806 .

[0178] In one example, the cavity of the gas converter 800 may be uniformly divided into three elongated chambers, as shown in FIGS. 8A-8B. Each chamber may be filled with a filtering material. For example, the filtering material may be prepared using aluminum silica gel particles with an average diameter of approximately 0.2 mm and vitamin C. First, approximately 5 g of vitamin C may be dissolved in 100 g of water to prepare a saturated aqueous solution of vitamin C. 100 g of aluminum silica gel particles may be added to the solution and mixed uniformly. The aluminum silica gel particles may be dried at approximately 100°C for approximately 0.5 hours. The gas converter 800 may be used to process a gas flow containing 100 ppm NO at a flow rate of 1.0 L / min for approximately 90 hours. Approximately 100% of the NO in the gas flow may be converted to NO.

[0179] Alternatively, a filtration material can be prepared using silica gel particles with an average diameter of about 3 mm and vitamin E. First, about 15 g of vitamin E can be prepared into a saturated solution. About 100 g of silica gel particles can be added to the solution and mixed uniformly. The silica gel particles can be dried at about 50°C for about 5 hours. The gas converter 800 can be used to process a gas flow containing 500 ppm NO2 at a flow rate of 4.0 L / min for about 5 hours. Approximately 100% of the NO2 in the gas flow can be converted to NO.

[0180] In another example, the cavity of the gas converter 800 may be uniformly divided into four elongated chambers, similar to the embodiment shown in FIGS. 8A-8B. Each chamber may be filled with a filtration material. The filtration material may be prepared using molecular sieve particles with an average diameter of approximately 5 mm and vitamin A. Approximately 25 g of vitamin A may be prepared as a saturated solution. Approximately 100 g of molecular sieve particles may be added to the solution and mixed uniformly. The molecular sieve particles may be dried at approximately 80°C for approximately 2 hours. The gas converter 800 may be used to process a gas flow containing 200 ppm NO at a flow rate of 2.0 L / min for a duration of approximately 70 hours. Approximately 100% of the NO in the gas flow may be converted to NO. Alternatively, the filtration material may be prepared using alumina particles with an average diameter of approximately 6 mm and vitamin C. Approximately 35 g of vitamin C may be prepared as a saturated solution. The alumina particles may be added to the solution and mixed uniformly. The alumina particles can be dried at about 120° C. for about 0.25 hours. The gas converter 800 can be used to process a gas flow containing 500 ppm NO at a flow rate of 1.0 L / min for a duration of about 125 hours. Approximately 100% of the NO in the gas flow can be converted to NO.

[0181] In another example, the cavity of the gas converter 800 may be uniformly divided into five elongated chambers, similar to the embodiment shown in FIGS. 8A-8B. Each chamber may be filled with a filtering material. The filtering material may be prepared using a sponge and vitamin E. Approximately 40 g of vitamin E may be prepared in a saturated solution. Approximately 100 g of sponge may be immersed in the solution. The sponge may be dried at approximately 150°C for approximately 0.2 hours. The gas converter 800 may be used to process a gas flow containing 800 ppm NO at a flow rate of 3.0 L / min for a duration of approximately 12 hours. Approximately 100% of the NO in the gas flow may be converted to NO. Alternatively, the filtering material may be prepared using cotton and vitamin A. Approximately 50 g of vitamin A may be prepared in a saturated solution. Approximately 100 g of cotton may be immersed in the solution. The cotton may be dried at approximately 70°C for approximately 3 hours. The gas converter 800 can be used to process a gas flow containing 400 ppm NO at a flow rate of 4.0 L / min for a duration of 35 hours. Approximately 100% of the NO in the gas flow can be converted to NO.

[0182] In some embodiments, the product gas released from the gas converter 800 is The output gas of the system may be 0. The mass and / or flow rate of the output gas of the system may be monitored. For example, the concentrations of NO, NO2, and moisture may be monitored. In some embodiments, a flow meter monitors the flow rate of the output gas of the system 10.

[0183] NO transport and / or monitoring The NO produced by system 10 can be used in a variety of NO-based therapies. For example, the NO produced by system 10 can be used in NO inhalation therapy. The NO produced by system 10 can be delivered to a patient in the presence or absence of another type of gas (e.g., oxygen gas). For example, the NO produced by system 10 can be delivered to a patient via air flow or oxygen gas flow provided by a ventilator.

[0184] 1 , system 10 includes a ventilation circuit 900 for delivering inhaled NO to a patient. In some embodiments, ventilation circuit 900 is located downstream of and in fluid communication with pressure vessel 600. Ventilation circuit 900 may also be located downstream of and in fluid communication with gas converter 800. Ventilation circuit 900 may be configured to connect system 10 to a breathing device or system for delivering NO in any suitable manner. For example, ventilation circuit 900 may connect system 10 to a ventilator, nebulizer, positive airway pressure device, oxygenator, etc.

[0185] 9 is a schematic diagram of a ventilation circuit 900 of system 10 according to some embodiments of the present disclosure. In some embodiments, ventilation circuit 900 includes an inspiratory circuit 904 and an expiratory circuit 922. Inspiratory circuit 904 may be configured to be fluidly connected to a ventilator 906, and the inspiratory circuit delivers a gas flow (e.g., air flow or oxygen gas flow) from ventilator 906 to a patient 910 via a mask or tubing. Expiratory circuit 922 can deliver exhaled gases from the patient 910 to ventilator 906.

[0186] 9 , ventilation circuit 900 includes a port 902 configured to receive an NO supply. For example, port 902 may be located along and in fluid communication with inhalation circuit 904. In some embodiments, port 902 is located downstream of and in fluid communication with pressure vessel 600 and / or gas converter 800. The NO supplied from pressure vessel 600 may be mixed with and / or entrained by oxygen gas or air flowing through inhalation circuit 904 to form gas mixture 907, which may be delivered to patient 910. In some embodiments, humidifier 908 is located downstream of port 902 and may humidify gas mixture 907 before delivery to patient 910.

[0187] In some embodiments, the ventilation circuit 900 includes a flow controller 916. The flow controller 916 may be located upstream of the port 902 and configured to control the flow rate of the gas flow (e.g., the NOx-containing product gas from the pressure vessel 600 or the gas converter 800) entering the port 902. The flow controller 916 may include an inlet port, an outlet port, a flow sensor, and a control valve. In some embodiments, the flow controller 916 is a mass flow controller.

[0188] In some embodiments, the vent circuit 900 includes a controller 918. The controller 918 can communicate with the flow controller 916 via a wired or wireless connection. The controller 918 can send a control signal to the flow controller 916 to adjust the rate of gas flow entering the port 902. For example, the controller 918 can receive a sensor signal from the flow controller 916 that indicates the rate of flow of product gas entering the port 902. The controller 918 can generate a control signal in response to the received sensor signal. The control signal can be sent from the controller 918 to the flow controller 916 to adjust the rate of gas flow entering the port 902.

[0189] In some embodiments, the ventilation circuit 900 includes a flow sensor 905 configured to measure the flow rate of the air or oxygen gas flow output from the ventilator 906. The flow sensor 905 may be located along the inhalation circuit 904, for example, upstream of the port 902. A controller 918 may communicate with the flow sensor 905 via a wired or wireless connection. The controller 918 may send a control signal to the flow controller 916 to adjust the rate of the gas flow entering the port 902 based on a sensor signal from the flow sensor 905. For example, the controller 918 may receive a sensor signal from the flow sensor 905 indicative of the rate of the oxygen gas flow output from the ventilator 906, and the controller may generate a control signal in response to the received sensor signal. Sending a control signal to the flow controller 916 to adjust the rate of the product gas entering the port 902 and mixing with the oxygen gas flow may allow for adjustment of the concentration of NO in the mixed gas delivered to the patient 910.

[0190] In some embodiments, the ventilation circuit 900 includes one or more gas sensors. The gas sensors may be any suitable sensor configured to detect one or more types of gas and capable of measuring the concentration of one or more components (e.g., NO, NO, O, and moisture) in the gas mixture 907. For example, the gas sensors may be electrochemical gas sensors, infrared gas sensors, or thermal conductivity gas sensors.

[0191] In some embodiments, ventilation circuit 900 includes a sampling port 912. Sampling port 912 may be located along and in fluid communication with inspiratory circuit 904 (e.g., downstream of humidifier 908). Sampling port 912 may be located upstream of an applicator (e.g., a mask or endotracheal tube). Sampling gas or a flow of sampling gas from sampling port 912 can be used to measure the concentration of each component of gas mixture 907.

[0192] In some embodiments, one or more gas sensors may be located near the sampling port 912, and the one or more gas sensors may communicate with the controller 918 via a wired or wireless connection. In some embodiments, the one or more gas sensors are located in the gas monitor 1100. Sample gas flow may flow from the sampling port 912 through the sampling circuit 914 to the gas monitor 1100. The gas monitor 1100 may communicate with the controller 918 via a wired or wireless connection. Sensor signals indicative of the concentration of one or more components (e.g., NO, NO, and O) may be transmitted from the gas sensors or the gas monitor 1100 to the controller 918. The controller 918 may generate control signals in response to the received sensor signals, and the controller may transmit the control signals to one or more components of the system to adjust the concentration of one or more components of the gas mixture 907. For example, the controller 918 can send a control signal to the energy source 114 to adjust the NO concentration or send a control signal to the flow controller 916 to adjust the concentrations of NO, NO2, and O2 in the gas mixture 907.

[0193] Gas monitor 1100 may include various features. For example, gas monitor 1100 may include an alarm device configured to provide one or more alarms (e.g., an audible or visual alarm) when the concentration of one or more measured gases in gas mixture 907 exceeds a preset threshold (e.g., 25 ppm for NO and 5 ppm for NO2). Gas monitoring device 1100 may include a display for displaying alarms and / or measured concentration values. Because gas mixture 907 may be passed through humidifier 908, the sample gas flow from port 912 may have a high humidity. Reducing or eliminating moisture in the sample gas flow of gas mixture 907 may improve the accuracy of one or more gas sensors of gas monitoring device 1100.

[0194] In some embodiments, the gas monitoring apparatus 1100 includes a moisture collector 1000 configured to reduce or remove moisture in a sample gas flow of the gas mixture 907. FIG. 10A is a perspective view of the moisture collector 1000 in accordance with some embodiments of the present disclosure. FIG. 10B is a partial perspective view of the moisture collector 1000. FIG. 10C is another partial perspective view of the moisture collector 1000. As shown in FIGS. 10A-10C, in some embodiments, the moisture collector 1000 includes one or more inlets (e.g., inlet 1008) and one or more outlets (e.g., first outlet 1010 and second outlet 1012). A gas flow 1009 (e.g., a sample gas flow from port 912) can enter the moisture collector 1000 via one or more inlets, and the gas flow can leave the moisture collector 1000 via one or more outlets. For example, as shown in FIG. 10A, a gas flow 1009 can enter the moisture collector 1000 via an inlet 1008, and the gas flow may be split into a first air flow 1014 and a second air flow 1016 that leave the moisture collector 1000 via a first outlet 1010 and a second outlet 1012, respectively.

[0195] In some embodiments, the moisture collector 1000 includes a cup 1002, a covering 1004, and a moisture filter 1006. In some embodiments, the moisture filter 1006 is disposed between the cup 1002 and the covering 1004. A gas flow 1009 can pass from an inlet 1008 through the moisture filter 1006 and exit through an outlet 1010 and / or an outlet 1012. The moisture filter 1006 is permeable to gas but impermeable to moisture (e.g., water droplets or water vapor). For example, the moisture filter 1006 may include a material with pores configured to allow gas molecules to pass through but not allow larger particles (e.g., water molecules or solid particles) to pass through. In some embodiments, the moisture filter 1006 includes a porous membrane. In some embodiments, the porous membrane is a gas-permeable membrane. In some embodiments, the porous membrane is a hydrophobic membrane.

[0196] In some embodiments, the moisture collector 1000 includes one or more flow paths configured to permit gas flow from an inlet to an outlet. In some embodiments, the moisture collector 1000 includes a first chamber 1018 and a second chamber 1020 that define the flow paths. The first chamber 1018 may be located downstream of and in fluid communication with the inlet 1008. The second chamber 1020 may be located downstream of and in fluid communication with the first chamber 1018, and the second chamber may be located upstream of and in fluid communication with the outlet 1010. The moisture filter 1006 may be located between the first chamber 1018 and the second chamber 1020. Gas flow 1009 can flow from first chamber 1018 through moisture filter 1006 to second chamber 1020, and the gas flow can become first gas flow 1014, which has a lower moisture level than gas flow 1009.

[0197] For example, moisture intercepted by the moisture filter 1006 may accumulate in the first chamber 1018 and on the moisture filter 1006. The accumulated moisture may form liquid droplets. The liquid droplets may accumulate on the side of the moisture filter 1006 facing the gas flow 1009 or the first chamber 1018, collect in the first chamber 1018, and flow to the cup 1002 through the opening 1022 of the first chamber 1018. Liquid accumulated on the moisture filter 1006, for example, on the side of the moisture filter 1006 facing the first chamber 1018, may reduce the throughput of the gas flow 1009 through the moisture filter. Such liquid accumulation may clog the pores in the gas-permeable membrane of the moisture filter 1006, reducing the gas throughput of the moisture collector 1000. In some embodiments, the moisture filter 1006 is angled so that gravity causes liquid to accumulate toward the edge of the moisture filter 1006.

[0198] In some embodiments, the moisture collector 1000 includes one or more additional flow paths to increase the amount of gas flow passing through the moisture collector 1000. For example, the moisture filter 1006 may include a third chamber 1024 and a fourth chamber 1026. The third chamber 1024 may be fluidly connected to the cup 1002, for example, via an opening. The fourth chamber 1026 may be downstream of and fluidly connected to the third chamber 1024, and the fourth chamber may be upstream of and fluidly connected to the outlet 1012. The moisture filter 1006 may be located between the third chamber 1024 and the fourth chamber 1026. 10A , a second gas flow 1016 can be directed from the moisture filter 1006 to the cup 1002, and the second gas flow can flow from the cup 1002 to the third chamber 1024, through the moisture filter 1006, and into the fourth chamber 1026. The second gas flow 1016 can leave the moisture collector 1000 via the outlet 1012. The second gas flow 1016 can clean the moisture filter 1006 of accumulated liquid (e.g., water) and improve gas throughput through the moisture filter 1006.

[0199] 11A-11D, one or more outlets of the moisture collector 1000 are in fluid communication with a gas detection circuit of the gas monitoring device 1100. For example, outlets 1010 and 1012 may be in fluid communication with the gas detection circuit. One or more gas flows from the moisture collector 1000 are available for use in measuring gas concentrations by the gas detection circuit. In some embodiments, a first gas flow 1014 from the moisture collector 1000 is used by the gas detection circuit to measure gas concentrations.

[0200] The gas detection circuit of the gas monitoring device 1100 may include various components and features for measuring gas concentrations and / or improving the accuracy of the measurements. In some embodiments, the gas monitoring device 1100 includes a sensing module 1102. The sensing module 1102 may include one or more gas sensors, such as an NO sensor 1102a, an NO sensor 1102b, and an O sensor 1102c. The one or more gas sensors may be disposed in one or more chambers configured to receive at least a portion of the gas flow (e.g., first gas flow 1014) circulating through the gas detection circuit. For example, as shown in FIGS. 11A-11D, a gas sensor may be disposed in one chamber to measure the gas concentration of the gas flowing therethrough. The gas monitoring device 1100 may include a computer-readable storage device and / or a processor (not shown) in wired or wireless communication with the sensors for receiving and processing detection signals received from the sensors. The gas monitoring device 1100 may include a processor, computer-readable storage device, and / or transmitter circuitry (not shown) in wired or wireless communication with the gas sensor for transmitting the sensing signal or reading to a controller, such as the control device 918, or an electronic device (e.g., a tablet computer, computer, or smartphone). The gas sensor reading may be obtained by the gas sensor or the processor based on the sensing signal.

[0201] In some embodiments, the gas detection circuit of the gas monitoring device 1100 includes a pump 1104. The pump 1104 is configured to generate or drive one or more gas flows through the gas detection circuit. In some embodiments, the gas detection circuit includes one or more valves configured to direct one or more gas flows through the gas detection circuit. For example, the gas detection circuit may include at least one check valve 1106, such as a spherical check valve. The check valve 1106 may be located in any suitable position to prevent backflow. For example, the pump 1104 may be located downstream of the gas detection circuit, allowing the gas flow from the pump outlet to be discharged to the environment. The check valve 1106 may be located downstream of the pump 1104 to prevent ambient air from flowing back into the gas detection circuit.

[0202] In some embodiments, the gas monitoring apparatus 1100 includes one or more selector valves configured to change the direction or flow path of gas flow through the gas detection circuit. For example, the gas monitoring apparatus 1100 may include a first selector valve 1110 and a second selector valve 1112. The selector valves may have one or more positions (e.g., a first position and a second position) for selecting the flow path or direction of gas through the gas detection circuit. A user interface may be used to manually or automatically select the position of the selector valves. The user interface may be, for example, a graphical user interface or a control panel, such as a switch or button.

[0203] In some embodiments, one or more selector valves may be provided in the control module 1114. As shown in FIGS. 11A-11D, the control module 1114 may include one or more connection ports, such as connection ports 1116A-1116G. The selector valves may fluidly connect one or more connection ports. Such a configuration may improve the ease of assembly and / or maintenance of the gas monitoring apparatus 1100. For example, the first selector valve 1110 may have a first position for fluidly connecting connection ports 1116A and 1116C, and the first selector valve may have a second position for fluidly connecting connection ports 1116A and 1116D. For example, second selector valve 1112 may have a first position for fluidly connecting connection ports 1116E and 1116G, and the second selector valve may have a second position for fluidly connecting connection ports 1116F and 1116G. In some embodiments, selected connection ports may be fluidly connected to form one or more flow paths. For example, connection ports 1116B and 1116C may be fluidly connected. Various uses of the selector valve in one or more operational steps of gas monitoring device 1100 are further described below.

[0204] In some embodiments, the gas monitor 1100 includes one or more pressure sensors. In some embodiments, the gas monitor 1100 includes at least one absolute pressure sensor 1118. In some embodiments, the gas monitor 1100 includes at least one differential pressure sensor 1120. The differential pressure sensor can be used to measure the rate of gas flow in the gas detection circuit. For example, the rate of gas flow can be calculated based on the differential pressure measured by the differential pressure sensor 1120 and Bernoulli's equation.

[0205] In some embodiments, the gas detection circuit of the gas monitoring apparatus 1100 includes one or more flow regulators, such as a first flow regulator 1122 and a second flow regulator 1124. The flow regulators may be flow controllers, flow limiters, or flow restrictors. The flow regulators may be configured to control the flow rate of the gas flow therethrough. For example, the flow regulators may be configured to limit the flow rate of the gas flow in the flow path to a particular range or value. In some embodiments, the first flow regulator 1122 is configured to regulate the first gas flow 1014 from the moisture collector 1000. In some embodiments, the second flow regulator 1124 is configured to regulate the second gas flow 1016 from the moisture collector 1000. In some embodiments, the differential pressure sensor 1120 is configured to measure the differential pressure across the flow regulators 1122.

[0206] In some embodiments, the gas monitoring device 1100 includes one or more filters. The filters may be located at any suitable location in the gas detection circuit to reduce or remove one or more types of impurities, such as moisture and solid materials, in the gas flow. Such filters can further reduce or remove moisture within the gas detection module to improve the accuracy of the gas sensor measurements. Additionally or alternatively, such filters can reduce or prevent solid materials from entering the valve, thereby increasing the lifespan of the gas monitoring device 1100.

[0207] In some embodiments, a filter 1128 is provided upstream of the gas detection module 1102. The filter 1128 may include a moisture filter configured to reduce or remove moisture, e.g., water, in the gas and / or liquid phase. The filter 1128 may include a membrane filter, e.g., a Nafion® membrane filter. The gas detection circuitry of the gas monitoring device 1100 may include one or more gas inlets (e.g., a first gas inlet 1127a and a second gas inlet 1127b) configured to receive an air flow from the environment or a gas supply (e.g., a compressed air supply). The filter 1126 may be provided downstream of the gas inlets to reduce or remove moisture and / or dust in the gas flow received from the gas inlets.

[0208] In some embodiments, the gas sensing circuitry includes one or more NO x Includes absorber 1108. NO x The absorber 1108 may be configured to absorb one or more nitrogen oxides, such as NO and NO. In some embodiments, NO x An absorber 1108 is provided upstream of the gas inlet to remove or reduce one or more nitrogen oxides, such as NO and NO, in the air flow that enters the gas detection circuit via the gas inlet. The gas detection circuit may include one or more gas outlets (e.g., gas outlet 1129) configured to output a gas flow (e.g., second gas flow 1016 or first gas flow 1014) to the environment. In some embodiments, NO x An absorber 1108 is provided downstream of the gas outlet to remove or reduce one or more nitrogen oxides, such as NO2 and NO, before discharging the gas flow to the environment.

[0209] NO x The absorber 1108 absorbs one or more nitrogen oxides NO x The absorbent material may include one or more absorbent materials configured to absorb NO and NO2. xThe absorbent material in absorber 1108 may be similar to the absorbent material in exhaust gas treatment device 700. x The absorber 1108 may have a structure similar to that of the exhaust gas treatment device 700. For example, the NO x The absorber 1108 may include a tortuous flow path that is at least partially filled with one or more types of absorbent material.

[0210] Various components of the gas monitor 1100 can be used for one or more operational processes, such as initialization, calibration, sampling, and cleaning. Such one or more operational processes may be automatically controlled by a processor and / or manually controlled by a user via a user interface (e.g., a control panel or a graphical user interface). Examples of various processes performed by the gas monitor 1100 are described below.

[0211] In some embodiments, the gas monitor 1100 is configured to perform an initialization process. FIG. 11A is a schematic diagram of an initialization process for the gas monitor 1000 according to some embodiments of the present disclosure. The initialization process can be performed to reduce or remove moisture in the gas detection circuit and / or to purge pre-existing gases from the gas detection circuit. For example, during the initialization process, ambient air is allowed to pass through at least a portion of the gas detection circuit. and through at least a portion of the gas detection circuit to dry and / or purge one or more flow paths of the detection module 1102 and / or the gas detection circuit.

[0212] 11A , during an initialization process, one or more selector valves can be switched to an appropriate position to fluidly connect selected connection ports and direct the flow of one or more gases in the gas detection circuit. For example, the first selector valve 1110 can be switched to its second position to fluidly connect connection ports 1116A and 1116D. The second selector valve 1112 can be switched to its second position to fluidly connect connection ports 1116F and 1116G. As shown by the arrows in FIG. 11A , during the initialization process, for example, the pump 1104 can generate air flow through the gas detection circuit (i.e., from the gas inlet 1127a, through connection ports 1116D and 1116A, the detection module 1102, the filter 1128, connection ports 1116G and 1116F, and to the outlet 1110). During the initialization process, the air flow may also pass through one or more of flow regulator 1122, filter 1126, flow regulator 1124, and check valve 1106. The air flow is filtered to remove NO before leaving the sensing circuit via gas outlet 1129. x It can flow through the absorber 1108 .

[0213] 11A, the pump 1104 can drive air flow through the outlet 1010, through the cup 1002, the outlet 1012, the connection ports 1116B and 1116C, and through the gas outlet 1129. The initialization process can be carried out for any suitable duration, such as less than about 1 minute, less than about 30 seconds, less than about 10 seconds, or less than about 1 second.

[0214] During the initialization process, it can be determined whether various components of the gas monitor 1100 are capable of operating under normal conditions. Additionally or alternatively, the gas monitor 1100 can generate one or more alarms to indicate one or more abnormal conditions in the gas detection circuit. For example, a selector valve can be switched to a different position to determine whether the valve is capable of operating under normal conditions. To determine whether the pump 1104 is capable of operating under normal conditions, the pump 1104 can be set to a certain flow rate and the rate of gas flow generated by the pump 1104 can be measured. When there is no gas flow in the gas detection circuit, the normal reading of the absolute pressure sensor 1118 may not exceed a preset value, for example, any value from about 600 mbar to about 1250 mbar, and the normal flow rate calculated based on the reading of the differential pressure sensor 1120 may not exceed a flow rate range preset by the pump's settings, for example, a flow rate range from about 50 ml / min to about 1000 ml / min.

[0215] In some embodiments, the gas monitoring device 1100 is configured to perform a calibration process to calibrate one or more gas sensors in the sensing module 1102. The calibration process can be performed regularly, for example, periodically, on demand, or before delivering the gas mixture 907 to a patient. The sensors can be calibrated using air (e.g., ambient air or compressed air) or a standard gas with known concentrations of its gas components. FIG. 11B is a schematic diagram of a calibration process for the gas monitoring device 1100 according to some embodiments of the present disclosure. In some embodiments, ambient air is used in the calibration process, as shown in FIG. 11B. For example, the first selector valve 1110 can be switched to its first position to fluidly connect the connection ports 1116B and 1116C. The second selector valve 1112 can be switched to its first position to fluidly connect the connection ports 1116E and 1116G. The pump 1104 can generate an air flow from the gas inlet 1127b through the connection ports 1116E and 1116G, the filter 1128, the detection module 1102, the connection ports 1116A and 1116C, and to the gas outlet 1129. x An absorber 1108 may be provided downstream of the gas inlet 1127b to remove or reduce NO and NO before the air flow passes through the detection module 1102. The air flow may pass through one or more of a flow regulator 1122, a filter 1126, and a check valve 1106.

[0216] During the calibration process, the pump 1114 can also drive the gas flow 1016 from the outlet 1012 through connection ports 1116B and 1116C to the gas outlet 1129. The gas flow 1016 can also pass through a filter 1126, a flow regulator 1124, a check valve 1106, and a NO x It may flow through one or more of the absorbers 1108 .

[0217] In some embodiments, a calibration process is performed to adjust the calibration curve of at least one sensor of the sensing module 1102, for example, to adjust the calibration curve using an offset value. The calibration process may include a zero calibration and / or a span calibration. For example, in a zero calibration, air flow from the environment is adjusted to a value equal to or greater than the NO x After passing through the absorber 1108, the air may be preset to have about 21% O, about 0% or 0 ppm NO, and about 0% or 0 ppm NO. The sensors in the sensing module can assume that the air flow readings correspond to these preset concentrations and can use offset values ​​to adjust their calibration curves.

[0218] In some embodiments, the span calibration can use one or more standard gases with known concentrations of O, NO, and / or NO during the calibration process. As shown in FIG. 11C , the first selector valve 1110 can be switched to its first position to fluidly connect connection ports 1116A and 1116C. The second selector valve 1112 can be switched to its second position to fluidly connect connection ports 1116F and 1116G. The pump 1104 can drive the standard gas from the outlet 11010 through connection ports 1116F, 1116G, filter 1128, the detection module 1102, connection ports 1116A and 1116C, and to the gas outlet 1129. Before releasing the standard gas flow via the gas outlet 1129, the standard gas flow further passes through a flow regulator 1122, a check valve 1106, and a NO filter. x It may pass through one or more of the absorbers 1108. The sensors of the sensing module may assume that the standard gas flow readings correspond to known concentrations of the standard gas and may use an offset value to adjust their calibration curves.

[0219] In some embodiments, the gas monitoring device 1100 is configured to perform a sampling process to measure the concentration of one or more gas components in a sample gas flow. FIG. 11C is a schematic diagram of a sampling process of the gas monitoring device 1100 according to some embodiments of the present disclosure. The sampling process can be performed on demand, or can be performed continuously or intermittently while delivering the gas mixture 907 to the patient 910. In some embodiments, during the sampling process, the gas detection circuit can receive a first gas flow 1014 from the outlet 1010 of the moisture collector 1000 and / or a second gas flow 1016 from the outlet 1012 of the moisture collector 1000. A first flow regulator 1122 can regulate the flow rate of the first gas flow 1014 to a first flow rate. A second flow regulator 1124 can regulate the flow rate of the second gas flow 1016 to a second flow rate. The first and second flow rates can be predetermined and adjusted based on settings of the pump 1104 and / or settings of the flow regulators 1122 and 1124. The first and second flow rates can be added together to form a flow rate for the pump 1104. For example, the flow rate for the pump 1104 can be in the range of about 50 mL / min to about 1000 mL / min, the first flow rate of the first gas flow 1014 can be in the range of about 40 mL / min to about 800 mL / min, and the second flow rate of the second gas flow 1016 can be in the range of about 10 mL / min to about 200 mL / min.

[0220] In some embodiments, the concentration in the first gas flow 1014 is measured during the sampling process. As shown in FIG. 11C , the first selector valve 1110 can be switched to its first position to fluidly connect connection ports 1116A and 1116C. The second selector valve 1112 can be switched to its second position to fluidly connect connection ports 1116F and 1116G. The pump 1104 can drive the first gas flow 1014 from the outlet 1010 through connection ports 1116F, 1116G, filter 1128, detection module 1102, connection ports 1116A and 1116C, and to the gas outlet 1129. Before releasing the first gas flow 1014 via the gas outlet 1129, the first gas flow further passes through a flow regulator 1122, a check valve 1106, and a NO x The second gas flow 1016 may pass through one or more of the flow regulator 1124, the check valve 1106, and the NOx absorber 1108. The pump 1104 may further drive the second gas flow 1016 from the outlet 1012 through the connection ports 1116B and 1116C to reach the gas outlet 1129. Before releasing the second gas flow 1016 via the gas outlet 1129, the second gas flow may further pass through one or more of the flow regulator 1124, the check valve 1106, and the NOx absorber 1108.

[0221] In some embodiments, one or more gas sensors in the detection module 1102 are configured to recognize and measure the concentration of one or more gas components (e.g., NO, NO, and O) in the first gas flow 1014 as it passes through the gas detection module 1102. Readings from these sensors may be transmitted via wired or wireless communication to a processor and / or computer-readable storage medium (not shown) in the gas monitoring device 1100 for further processing and / or transmission to one or more other devices.

[0222] The accuracy of one or more sensors in the sensing module 1102 can be improved if the first gas flow 1014 passes through the sensors at a preset rate or within a preset rate range. In some embodiments, the rate of the first gas flow 1014 is regulated and controlled by a flow regulator 1122, and a differential pressure sensor 1120 is used to measure the rate of the first gas flow 1014 passing through the flow regulator 1122. The preset rate or rate range can be any suitable value or range based on the type of sensor. For example, one or more sensors can be electrochemical sensors, and the preset rate range can be from about 50 ml / min to about 450 ml / min, e.g., from about 220 ml / min to about 240 ml / min. The pump 1104 can be used to regulate the rate of the first gas flow 1014 passing through the sensing module to a preset value or range.

[0223] In some embodiments, the gas monitoring apparatus 1100 is configured to perform a cleaning process to reduce or remove liquid accumulation in the moisture filter 1006 and / or gas detection circuitry of the moisture collector 1000. FIG. 11D is a schematic diagram of a cleaning process for the gas monitoring apparatus 1100, according to some embodiments of the present disclosure. As shown in FIG. 11D , the first selector valve 1110 can be switched to its second position to block the first gas flow 1014 by blocking connection ports 1116A and 1116C. The second selector valve 1112 can be switched to its first position to fluidly connect connection ports 1116E and 1116G. The pump 1104 can drive the second gas flow 1016 from the outlet 1012 through connection ports 1116B and 1116C to the gas outlet 1129. Before releasing the second gas flow 1016 via gas outlet 1129, the second gas flow further passes through filter 1126, flow regulator 1124, check valve 1106 and NO x It may pass through one or more of the absorbers 1108 .

[0224] During the cleaning process, shutting off the first gas flow 1014 allows an increase in the flow rate of the second gas flow 1016. As shown in Figure 10A, before leaving the outlet 1012, the second gas flow 1016 can flow from the first chamber 1018 into the cup 1002 and back to the moisture filter 1006, for example, to one side of the moisture filter 1006 facing the gas flow 1009 or to one side facing the first chamber 1018, where liquid can accumulate. Increasing the flow rate of the second gas flow 1016 can increase the drying or cleaning of liquid accumulated in the moisture filter 1006.

[0225] The gas monitor 1100 can perform a cleaning process based on need and / or when one or more abnormal conditions occur. The cleaning process can be performed for any suitable duration, such as less than about 2 minutes, less than about 1 minute, less than about 30 seconds, or less than about 10 seconds. The cleaning process can be initiated automatically or manually. For example, if liquid blocks at least a portion of the moisture filter 1006 and / or the flow path in the gas detection circuit, the processor of the gas monitor 1100 can initiate the cleaning process in response to one or more abnormal readings from the absolute pressure sensor 1118 and / or the differential pressure sensor 1120. For example, during the sampling process, the normal absolute pressure measured by the pressure sensor 1118 may be in the range of about 0.5 bar to about 1.25 bar. An absolute pressure exceeding this range can indicate that the moisture filter 1006 and / or the gas detection circuit are blocked by liquid. The normal flow rate range calculated based on the differential pressure measured by the pressure sensor 1120 may be from about 20 ml / min to about 275 ml / min, e.g., from about 20 ml / min to about 50 ml / min, from about 50 ml / min to about 100 ml / min, from about 100 ml / min to about 150 ml / min, from about 150 ml / min to about 200 ml / min, from about 200 ml / min to about 250 ml / min, or from about 250 ml / min to about 275 ml / min. A flow rate below this range may indicate that the moisture filter 1006 and / or the gas detection circuitry is blocked by liquid.

[0226] As described herein, the modularization of system 10 may allow one or more of its components, such as reaction chamber 102, reaction medium 112, one or more electrodes (e.g., first electrode 116, second electrode 118), filtration system 500 or its filters, pressure vessel 600, waste gas treatment device 700, gas converter 800, and flow control devices, to be easily replaced, maintained, or repaired without requiring substantial removal of system 10. Thus, maintenance costs for system 10 may be reduced and the operational life of system 10 may be extended.

[0227] In some embodiments, system 10 may include a user interface in communication with control circuitry. The user interface may include one or more controllers for receiving commands from a user to adjust system parameters, such as the number of stages, the number of operating cycles in each stage, and the concentration and / or flow rate of NO in a stage or operating cycle. The control circuitry may send control signals to various components, such as energy source 114, carrier gas source 200, and flow controllers or controls, to adjust these system parameters.

[0228] Various methods for generating and / or delivering NO can use system 10 or one or more components thereof, such as the NO generating facility 100 described herein. For example, system 10 or NO generation equipment 100 can be used to generate NO as needed. In some embodiments, system 10 or NO generation equipment 100 can be used to provide a stable supply of NO at a preset concentration within a ramp period. A ramp period may refer to a transient period during which the NO concentration of the product gas can change from an initial concentration to a preset steady-state concentration. For example, during a ramp period, the NO concentration of the product gas increases from an initial concentration (e.g., zero) to a preset steady-state concentration. System 10 or NO generation equipment 100 can be used to provide a stable supply of NO within one or more stages or one or more operating cycles. System 10 can be used to reduce or minimize exposure to potentially air pollutants and / or toxic gases (e.g., nitrogen dioxide) during NO generation or delivery. System 10 can be used to deliver NO using another type of treatment gas (e.g., oxygen gas or air) provided by a breathing device (e.g., a ventilator). System 10 can be used to monitor the concentration of one or more components of a gas mixture being delivered to or inhaled by a patient.

[0229] As described herein, steps of the disclosed methods may be modified in any manner, including by rearranging steps, inserting steps, and / or deleting steps. Unless otherwise stated, one or more steps of the disclosed methods may be performed simultaneously or in any suitable time order.

[0230] FIG. 12 is a flowchart illustrating a method 1200 for generating NO according to some embodiments of the present disclosure. In some embodiments, as shown in FIG. 12, method 1200 includes steps 1202-1210. In some embodiments, step 1202 includes applying a voltage or current to one or more electrodes of a plurality of electrodes disposed in a reaction medium by an energy source to generate NO. The plurality of electrodes may include a cathode. In some embodiments, NO is generated at or near one or more surfaces of the plurality of electrodes. The reaction medium may be contained within a reaction chamber of the NO generation facility. In some embodiments, the reaction chamber includes a gas region and a liquid region, and the reaction medium is disposed in the liquid region.

[0231] In some embodiments, in step 1202, the voltage or current applied to the plurality of electrodes can be predetermined and / or adjusted based on one or more conditions (e.g., a desired NO concentration in the output product gas). In some embodiments, the preset voltage range is from about 1.4 V to about 5.0 V. In some embodiments, the preset current range is from about 0 mA to about 300 mA. The rate of NO production can increase with increasing voltage or current applied to the plurality of electrodes. In some cases, applying a current of about 0 mA to the plurality of electrodes may produce NO. In some embodiments, step 1202 includes terminating the voltage or current applied to the plurality of electrodes.

[0232] In some embodiments, step 1202 includes applying an excitation voltage or excitation current to the plurality of electrodes within an excitation period prior to applying the preset voltage or preset current. The excitation period may range from about 0.5 minutes to about 5 minutes, e.g., from about 0.5 minutes to about 1 minute, from about 1 minute to about 2 minutes, from about 2 minutes to about 3 minutes, from about 3 minutes to about 4 minutes, from about 4 minutes to about 5 minutes, or a combination thereof. In some embodiments, the excitation voltage is about 2 to about 8 times the preset voltage. In some embodiments, the excitation current is about 2 to about 8 times the preset current.

[0233] In some embodiments, step 1202 includes switching the polarity of two electrodes (e.g., a cathode and an anode). For example, step 1202 may include reversing the polarity of an energy source, for example, by reversing the polarity of a DC power source or using an AC power source. The polarity of the two electrodes can be switched based on need or based on a preset schedule. For example, the polarity of the two electrodes may be switched periodically, for example, every about 10 minutes to about 10 hours.

[0234] In certain embodiments, method 1200 includes step 1204. In certain embodiments, step 1204 includes receiving a carrier gas by an NO-generating facility via an inlet circuit of the NO-generating facility. The inlet circuit may be in fluid communication with at least one sparger disposed within the reaction medium. The at least one sparger may be located near one or more of the electrodes. In certain embodiments, a carrier gas is received from a carrier gas source. In certain embodiments, the carrier gas includes nitrogen gas. In certain embodiments, step 1204 includes generating the carrier gas from compressed air by the carrier gas source. For example, a nitrogen gas generating facility may be used to generate the carrier gas from compressed air.

[0235] In certain embodiments, step 1204 includes controlling the flow rate of the carrier gas received through the inlet circuit with a flow controller. In certain embodiments, step 1204 includes receiving the carrier gas at a constant flow rate ranging from about 50 mL / min to about 12 L / min, e.g., from about 0.5 L / min to about 1 L / min, from about 1 L / min to about 3 L / min, from about 3 L / min to about 5 L / min, from about 5 L / min to about 8 L / min, from about 8 L / min to about 10 L / min, from about 10 L / min to about 12 L / min, or a combination thereof.

[0236] In some embodiments, step 1204 includes purging the system 10 using a carrier gas. For example, the carrier gas can pass through some or all of the gas flow regions or pathways of the system, such as the gas region of the reaction chamber, the inlet and outlet circuits, the circulation circuit, and the pressure vessel. Purging the system 10 using a carrier gas can reduce oxidation of NO produced in the product gas to toxic nitrite oxides (e.g., NO). Purging the system 10 can extend the life of gas converters configured to reduce or remove NO.

[0237] In certain embodiments, method 1200 includes step 1206. In certain embodiments, step 1206 includes sweeping a surface of one or more of the plurality of electrodes using a carrier gas. Sweeping the surface of the electrode can sweep, purge, and / or entrain NO generated at or near the surface of the electrode out of the reaction medium. This can produce a product gas that can include the generated NO and the carrier gas. In certain embodiments, at least a portion of the product gas is received and / or accumulated in a gas region of a reaction chamber of the NO-producing facility.

[0238] In certain embodiments, step 1206 includes generating bubbles of a carrier gas and causing them to sweep over a surface of one or more of the plurality of electrodes. For example, step 1206 may include receiving a carrier gas with a sparger, and may include projecting bubbles of the carrier gas through the sparger at the reaction medium and causing them to sweep over a surface of one or more of the plurality of electrodes. The sparger may be in fluid communication with the inlet circuit, and the sparger may be disposed within the reaction medium and proximate to one or more of the plurality of electrodes. The bubbles emitted by the sparger may propagate along a bubble path, and the bubble path may extend along a surface of at least one electrode.

[0239] In certain embodiments, method 1200 includes step 1208. In certain embodiments, step 1208 includes circulating a first fluid flow to the reaction chamber using a first circulation circuit. In certain embodiments, step 1208 includes generating a first fluid flow from an inlet to an outlet of the first circulation circuit with a gas pump. In certain embodiments, the first fluid flow includes the product gas flow generated in step 1206. In certain embodiments, step 1208 includes filtering the recirculating fluid flow using one or more filters upstream of the gas pump. The one or more filters can reduce or remove liquid and / or solid materials in the recirculating fluid flow before the recirculating fluid flow enters the gas pump.

[0240] In some embodiments, step 1208 may include circulating the first fluid flow at a constant flow rate ranging from about 0.5 L / min to about 5.0 L / min, e.g., from about 0.5 L / min to about 1.0 L / min, from about 1.0 L / min to about 1.5 L / min, from about 1.5 L / min to about 2.0 L / min, from about 2.0 L / min to about 2.5 L / min, from about 2.5 L / min to about 3.0 L / min, from about 3.0 L / min to about 3.5 L / min, from about 3.5 L / min to about 4.0 L / min, from about 4.0 L / min to about 4.5 L / min, from about 4.5 L / min to about 5.0 L / min, or a combination thereof.

[0241] In certain embodiments, method 1200 includes step 1210. In certain embodiments, step 1210 includes transmitting a product gas containing NO from the reaction chamber through an outlet circuit. In certain embodiments, the outlet circuit is in fluid communication with a gas volume of the reaction chamber. In certain embodiments, the NO concentration in the product gas transmitted from the reaction chamber can reach a steady state within a ramp period. For example, the ramp period can range from about 2 minutes to about 10 minutes.

[0242] In some embodiments, the method 1200 may include one or more steps selected from steps 1212-1222 below.

[0243] In some embodiments, method 1200 includes step 1212. In some embodiments, step 1212 includes measuring the concentration of NO in the product gas using an NO concentration sensor. In some embodiments, the NO concentration sensor may be disposed in contact with the product gas in the gas region to measure the NO concentration in the gas region. In some embodiments, the NO concentration sensor may be disposed in an outlet circuit of the reaction chamber, near the outlet circuit of the reaction chamber, or downstream of the outlet circuit of the reaction chamber to detect the NO concentration in the product gas away from the reaction chamber. For example, the NO sensor may be disposed at an opening in the outlet circuit, in a conduit in the outlet circuit, or downstream of a filter disposed downstream of the outlet circuit.

[0244] In some embodiments, method 1200 includes step 1214. Step 1214 can reduce or remove dissolved NO in the reaction medium after producing NO within a stage or operating cycle. Step 1214 can include separating at least a portion of the dissolved NO from the reaction medium. Step 1214 can further include treating the separated NO, for example, by use of an exhaust gas treatment device.

[0245] In some embodiments, step 1214 includes circulating a second fluid flow through the reaction chamber using a second circulation circuit. In some embodiments, the second fluid flow in the second circulation circuit includes a liquid flow. In some embodiments, the second fluid flow in the second circulation circuit includes a gas flow. In some embodiments, step 1214 is performed before, during, and / or after generating NO using the reaction medium in step 1202. For example, generating NO within a phase or operating cycle may be followed by increasing the voltage or potential applied to the electrodes. After terminating the flow, step 1214 can be performed. Step 1214 can be performed before initiating application of voltage or current to the electrodes to generate NO for use in the next stage or cycle of operation.

[0246] In certain embodiments, step 1214 includes configuring and / or operating the second circulation circuit to operate in a working mode. In the working mode, the second fluid flow may include a reaction medium flow. In certain embodiments, operating the second circulation circuit in a working mode includes using a pump to circulate the second fluid flow from a first port of the second circulation circuit, through a liquid-gas separator, and out a second port of the second circulation circuit. The first port may be in fluid communication with a liquid region of the reaction chamber, and the second port may be in fluid communication with a gas region of the reaction chamber.

[0247] In the working mode, the second fluid flow can be circulated at any suitable flow rate, for example, flow rates ranging from about 0.1 L / min to about 0.5 L / min, from about 0.5 L / min to about 1.0 L / min, from about 1.0 L / min to about 3.0 L / min, from about 3.0 L / min to about 5.0 L / min, from about 5.0 L / min to about 8.0 L / min, or combinations thereof. The second circulation circuit can operate in the working mode for any suitable time, for example, less than about 0.5 minutes, less than about 1 minute, less than about 2 minutes, less than about 5 minutes, less than about 10 minutes, or less than about 20 minutes.

[0248] In certain embodiments, operating the second circuit in a working mode includes separating NO from the reaction medium while the second fluid flow is passing through the liquid-gas separator. In certain embodiments, operating the second circuit in a working mode includes passing a sweep gas through the liquid-gas separator to entrain the NO separated from the second fluid flow as a mixed gas from the liquid-gas separator. In certain embodiments, operating the second circuit in a working mode includes conveying the mixed gas to a waste gas treatment device before releasing the mixed gas to the environment.

[0249] In some embodiments, step 1214 includes configuring and / or operating the second circulation circuit in a cleaning mode. The cleaning mode can be activated after the working mode. In the cleaning mode, the second fluid flow can include a gas flow. In some embodiments, operating the second circulation circuit in the cleaning mode includes using a pump to circulate the second fluid flow from a second port of the second circulation circuit, through the liquid-gas separation device, and out a first port of the second circulation circuit. In some embodiments, operating the second circulation circuit in the cleaning mode includes pumping the remaining reaction medium in the liquid-gas separation device back into the reaction chamber. The cleaning mode can prepare the liquid-gas separation device for a next working mode, for example, by drying the separation membrane of the liquid-gas separation device.

[0250] In the cleaning mode, the second fluid flow can be circulated at any suitable flow rate, for example, from about 0.25 L / min to about 0.5 L / min, from about 0.5 L / min to about 1.0 L / min, from about 1.0 L / min to about 3.0 L / min, from about 3.0 L / min to about 5.0 L / min, or combinations thereof. The second circulation circuit can operate in the cleaning mode for any suitable time, for example, less than about 0.5 minutes, less than about 1 minute, less than about 2 minutes, or less than about 5 minutes.

[0251] In some embodiments, step 1214 may include placing a selector valve in a first position to allow the second circulation circuit to operate in a working mode, and the step may include placing the selector valve in a second position to allow the second circulation circuit to operate in a cleaning mode.

[0252] In certain embodiments, step 1214 includes purging the reaction chamber (e.g., a gas volume of the reaction chamber) using a carrier gas. The carrier gas can accumulate in the gas volume of the reaction chamber, and the carrier gas can be circulated in a second circulation circuit in a cleaning mode.

[0253] In some embodiments, method 1200 includes step 1216. In some embodiments, step 1216 includes transmitting the product gas from the reaction chamber through a filtration system. Step 1216 may include reducing or removing one or more impurities in the product gas, such as solid matter (e.g., salt aerosols) and moisture, with the filtration system. The filtration system may include one or more filtration devices or filters.

[0254] In some embodiments, method 1200 includes step 1218. In some embodiments, step 1218 includes transmitting the product gas to a pressure vessel. In some embodiments, step 1218 includes receiving and storing the product gas in the pressure vessel for a pressure hold period. At the end of the pressure hold period, the pressure and / or NO concentration in the pressure vessel can increase to a preset level or a preset range. In some embodiments, the pressure vessel includes a first region and a second region. Step 1218 may include receiving the product gas through an inlet fluidly connected to the first region of the pressure vessel. Step 1218 may include storing the product gas in the first region of the pressure vessel. Step 1218 may include releasing the product gas from the pressure vessel, for example, through an outlet fluidly connected to the first region. The concentration of NO in the product gas released from the pressure vessel can reach a steady state within a ramp period. A ramp period may refer to a transient period during which the NO concentration in the product gas can change from an initial concentration to a preset steady-state concentration. In some embodiments, step 1218 may include measuring and / or adjusting the flow rate of the product gas released from the pressure vessel using a flow controller, which may adjust the flow rate of the product gas based on commands received from the controller.

[0255] In some embodiments, step 1218 includes receiving and storing the product gas in a second region in fluid communication with the first region. Step 1218 may include storing the product gas in the second region at a pressure less than or equal to a preset threshold. Step 1218 may include releasing the product gas stored in the second region from the second region to the first region, and may further include releasing the product gas from the first region out of the pressure vessel. In some embodiments, step 1218 includes releasing gas from the pressure vessel (e.g., from a second region of the pressure vessel) via a pressure relief valve when pressure in one or more regions of the pressure vessel exceeds a preset threshold. In some embodiments, step 1218 includes treating the gas released by the pressure relief valve, for example, with a waste gas treatment device.

[0256] In some embodiments, method 1200 includes step 1220. In some embodiments, step 1220 may include conveying the product gas through a gas converter to reduce or remove one or more toxic nitrogen oxides, e.g., NO, in the product gas. In some embodiments, step 1220 includes absorbing or converting some or all of the toxic nitrogen oxides, e.g., NO, as the product gas passes through the gas converter. The toxic nitrogen oxides can be converted to NO. Step 1220 may include conveying the product gas from an inlet through a tortuous flow path to an outlet of the gas converter, and may include conveying the product gas through a filtration material in the tortuous flow path. Step 1220 may include absorbing some or all of the toxic nitrogen oxides in the product gas using the filtration material. Additionally or alternatively, step 1220 may include converting some or all of the toxic nitrogen oxides in the product gas to NO using the filtration material.

[0257] In some embodiments, method 1200 includes step 1222. In some embodiments, step 1222 includes delivering NO or a gas mixture containing NO to the patient using a ventilation circuit. The gas mixture may include one or more gas components, such as air, oxygen gas, and moisture. In some embodiments, step 1222 includes delivering NO or the gas mixture to the patient via an inspiratory circuit of the ventilation circuit. In some embodiments, step 1222 includes receiving exhaled gas from the patient via an expiratory circuit of the ventilation circuit.

[0258] In some embodiments, step 1222 includes delivering the NO with a gas flow (e.g., air flow or oxygen gas flow) provided by a breathing apparatus (e.g., a ventilator) connected to the ventilation circuit. For example, step 1222 may include combining the gas flow (e.g., air flow or oxygen gas flow) provided by the breathing apparatus (e.g., a ventilator) with a product gas flow received from the NO system to generate a gas mixture. In some embodiments, step 1222 includes humidifying the gas mixture before delivering the gas mixture to the patient.

[0259] In some embodiments, step 1222 includes measuring a flow rate of a gas flow (e.g., air flow or oxygen gas flow) delivered from a breathing device (e.g., a ventilator) using a flow sensor. The flow sensor may communicate with a controller via a wired or wireless connection. Step 1222 may further include transmitting a sensed signal or reading from the flow sensor to the controller.

[0260] In some embodiments, step 1222 includes measuring the concentration of one or more components of the gas mixture to be delivered to the patient with one or more gas sensors or a gas monitor including one or more gas sensors. For example, step 1222 may include obtaining a sample gas flow of the gas mixture to be delivered to the patient and measuring the concentration of one or more components of the sample gas flow. The one or more gas sensors or gas monitor may communicate with the controller via a wired or wireless connection. Step 1222 may include transmitting a detection signal or reading from the one or more gas sensors or gas monitor to the controller. In some embodiments, step 1222 includes providing an alarm when one or more readings of the one or more gas sensors are higher or lower than a threshold value. The alarm may be in any suitable form, such as an audible or visual alarm, and may be of any suitable duration.

[0261] In some embodiments, step 1222 includes controlling the flow rate of the product gas to mix or combine with a gas flow (e.g., air flow or oxygen gas flow) provided by a breathing apparatus (e.g., a ventilator). For example, the controller can be in communication with a flow controller configured to control the flow rate of the product gas from the NO system. The controller can send instructions to the flow controller to adjust the flow rate of the product gas. The controller can generate the instructions based on one or more sensed signals or readings of one or more flow sensors and / or one or more gas sensors.

[0262] In some embodiments, step 1222 includes controlling the rate of air flow or oxygen gas flow provided by the ventilator. For example, the controller may be in wired or wireless communication with the ventilator. The controller may command the ventilator. A command can be sent to adjust the flow rate of air or oxygen gas.

[0263] In some embodiments, step 1222 includes operating the gas monitor in one or more operational steps to measure the concentration of one or more components of the gas mixture to be delivered to the patient. For example, step 1222 may include performing one or more of an initialization step, a cleaning step, a sampling step, and a calibration step.

[0264] The foregoing descriptions are presented for illustrative purposes. They are not exhaustive and are not limited to the precise forms or examples disclosed. Modifications and adaptations of the embodiments will be apparent from consideration of the specification and practice of the disclosed embodiments. For example, while the described embodiments include hardware, systems and methods consistent with the present disclosure can be implemented in both hardware and software. Also, while certain components are described as already connected to each other, these components may be integrated together or distributed in any suitable manner.

[0265] Additionally, although this document has previously described illustrative examples, the scope includes any and all examples having equivalent elements, modifications, omissions, combinations (e.g., combinations across aspects of various embodiments), adaptations, and / or substitutions based on this disclosure. Additionally, the steps of the disclosed methods can be modified in any manner, including rearranging steps, inserting steps, or deleting steps.

[0266] The features and advantages of the present disclosure will be apparent from the detailed description, and because numerous modifications and variations will occur upon study of the subject matter of this disclosure, it is not desired to limit the subject matter of this disclosure to the exact construction and operation shown and described, and therefore, all suitable modifications and equivalents may be employed that fall within the scope of the present disclosure.

[0267] It should be understood that the above embodiments can be implemented by hardware, software (program code), or a combination of hardware and software. If implemented by software, it may be stored in the computer-readable medium. When executed by a processor, the software can perform at least some steps of the disclosed method.

[0268] In the foregoing specification, examples are described with reference to many specific details, which may vary from embodiment to embodiment. Certain adaptations and modifications can be made to the above examples. Other examples will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. The specification and examples are intended to be considered merely exemplary, with the true scope and spirit of the present disclosure being indicated by the appended claims. The order of steps shown is also for illustrative purposes only and does not imply that all steps must be performed for any given method of operation, nor that all steps are limited to any particular order of steps. Thus, those skilled in the art will recognize that steps may be performed in different orders to implement the same method. Additionally, the illustrated equipment is illustrative only, and a given equipment or system may include different combinations of components or modules of these equipment.

Claims

1. a reaction chamber having a liquid region configured to contain a reaction medium and a gas region configured to contain a product gas comprising NO; a plurality of electrodes disposed in the reaction medium, the plurality of electrodes including a cathode; an energy source electrically connected to the plurality of electrodes and configured to apply a predetermined voltage or a predetermined current to the cathode to generate NO; a sparger disposed within the reaction medium; an inlet circuit in fluid communication with the sparger and configured to deliver a carrier gas to the sparger; an outlet circuit in fluid communication with a gaseous region of the reaction chamber and configured to transmit the product gas from the reaction chamber; a recirculation circuit including a circulation inlet in fluid communication with the gas region of the reaction chamber and configured to receive a product gas flow from the gas region, a circulation outlet in fluid communication with the sparger, and a pump configured to generate a fluid flow of product gas from the circulation inlet through the circulation outlet to the sparger; Equipment for producing nitric oxide (NO).

2. 10. The apparatus of claim 1, further comprising a pressure vessel in fluid communication with the outlet circuit and configured to receive product gas from the outlet circuit, store the received product gas at a predetermined pressure or at a pressure lower than the predetermined pressure, and release the received product gas.

3. The facility of claim 1 , wherein the fluid flow comprises a product gas flow.

4. 2. The apparatus of claim 1, wherein the sparger is disposed adjacent to the cathode and configured to emit gas bubbles within the reaction medium so as to propagate along a surface of the cathode.

5. 10. The apparatus of claim 1, wherein the reaction chamber includes a first side and a second side opposite the first side, and the cathode includes an electrode plate positioned approximately perpendicular to the second side of the reaction chamber.

6. 6. The apparatus of claim 5, wherein the electrode plate includes a surface, a first edge extending along a first side of the reaction chamber, and a second edge opposite the first edge and extending along a second side of the reaction chamber.

7. 7. The apparatus of claim 6, wherein the sparger is disposed between the second side of the reaction chamber and the second edge of the electrode plate and is configured to emit gas bubbles along a gas bubble path extending from the second edge to the first edge of the electrode plate.

8. 10. The facility of claim 1, wherein the reaction medium comprises a buffer solution, a source of nitrite ions, and a catalyst.

9. The apparatus of claim 1 , wherein the preset current is between 0 mA and 600 mA.

10. The pressure vessel comprises: a body defining an internal cavity including a first region and a second region in fluid communication with and downstream of the first region; a gas inlet and a gas outlet in fluid communication with the first region; a plurality of baffles defining a tortuous flow path through the first region and the second region; 3. The apparatus of claim 2, further comprising: a pressure relief valve disposed in the body and in fluid communication with the second region.

11. 2. The installation of claim 1, further comprising a filtration device disposed in the recirculation circuit downstream of the circulation inlet and upstream of the pump, the filtration device configured to reduce or remove one or more types of liquid and / or solid impurities in the fluid flow.

12. 2. The apparatus of claim 1, further comprising a carrier gas source disposed upstream of and in fluid communication with the inlet circuit and configured to generate the carrier gas or supply the carrier gas to the inlet circuit.

13. 3. The equipment of claim 2, further comprising a ventilation circuit configured to connect to a breathing apparatus, the ventilation circuit including an inhalation circuit downstream of and in fluid communication with the breathing apparatus and the pressure vessel.

14. The intake circuit includes: an inlet configured to receive a flow of air or oxygen gas from the breathing apparatus; a port downstream of the inlet configured to receive product gas from the pressure vessel; a flow sensor disposed downstream of the inlet and configured to measure a flow rate of the air flow or the oxygen gas flow; an outlet configured to transport a gas mixture comprising product gas from the pressure vessel and air or oxygen gas from the breathing apparatus.

15. 15. The arrangement of claim 14, wherein the inlet circuit further comprises a sampling port disposed upstream of the outlet and configured to output a sample gas flow of the gas mixture.

16. receiving the sample gas flow; ２ , NO and O ２ 16. The facility of claim 15, further comprising a gas monitor including one or more gas sensors configured to measure the concentration of one or more of:

17. a flow control device configured to control the flow rate of product gas from the pressure vessel into the inlet circuit; in communication with the flow sensor, the flow controller, and the gas monitor; 17. The installation of claim 16, further comprising: a controller configured to receive one or more sensing signals or readings from the gas monitor and / or the flow sensor, generate instructions based on the one or more sensing signals or readings, and send the instructions to the flow controller to adjust the flow rate of product gas entering the intake circuit.

18. applying a preset voltage or a preset current by an energy source to one or more of a plurality of electrodes to produce NO, the plurality of electrodes being disposed in a reaction medium contained within a reaction chamber and including a cathode, the reaction chamber including a gas region configured to contain a product gas including NO and a liquid region configured to contain the reaction medium; receiving a carrier gas via an inlet circuit in fluid communication with a sparger disposed within the reaction medium; bubbling the carrier gas through the reaction medium with the sparger to graze the surface of one or more of the electrodes; transmitting the product gas from the reaction chamber through an outlet circuit in fluid communication with a gas region of the reaction chamber; at least a portion of the product gas is circulated in a recirculation circuit back to the sparger in the reaction chamber; A method for producing nitric oxide (NO).

19. 20. The method of claim 18, wherein the product gas is further transmitted through a pressure vessel in fluid communication with an outlet circuit.

20. 20. The method of claim 18, further comprising circulating a portion of the product gas from the gas region of the reaction chamber to the sparger through a pump in a recirculation circuit.

21. 21. The method of claim 20, further comprising combining the carrier gas with a circulating product gas upstream of the sparger.

22. 20. The method of claim 18, further comprising applying an excitation voltage or current to at least one electrode of the plurality of electrodes within an excitation period prior to applying the preset voltage or the preset current.

Images