Device for production of hydrogen peroxide with jet reactor and method of use thereof

Abstract

A device (10) for producing hydrogen peroxide (H2O2), includes a reservoir (11) for containing an initial volume of water (70), a compressor (26) for conveying liquid from the reservoir under pressure through a tube (13), and an elongated non-ionizing electrode (15) inside the tube (13) and protruding from its end (14). An ionizing electrode (17) in spaced relationship with the non-ionizing electrode forms an air gap (18) in which a positive polarity corona discharge zone is formed whereby water passing through the corona discharge zone is converted to hydrogen peroxide. The compressor conveys liquid through the tube at sufficient pressure to create a high-pressure jet that emerges from the end of the tube and passes through the corona discharge zone without fouling the air gap regardless of an angular displacement of the tube from an initial orientation within a prescribed limit.

Description

[0001] Device for Production of Hydrogen Peroxide with Jet Reactor and Method of Use Thereof

[0002] FIELD OF THE INVENTION

[0003] The invention relates to methods and devices for the production of hydrogen peroxide (H2O2).

[0004] BACKGROUND OF THE INVENTION

[0005] Methods and devices are known for the generation of hydrogen peroxide operating on the principle of conveying air-liquid or vapor flow through a corona discharge zone in air. One such example is disclosed in WO 2016 / 103246. In some devices operating on this principle, water is passed through a reactor having a nonionizing electrode located within the liquid, and an ionizing electrode located above the surface of the water so as to create a small air gap between the ionizing electrode and the water surface. High voltage DC is applied to these electrodes to initiate a corona discharge in the air gap owing to the conductivity of the water, which acts as an extension of the non-ionizing electrode.

[0006] CN 108128755A discloses a roller type water mist hydrogen peroxide preparation device in which water is conveyed linearly through a corona discharge zone.

[0007] U.S. Pat. No. 11,254,569 discloses a device for generating hydrogen peroxide wherein liquid water is conveyed on to a surface of a rotating first electrode facing a second static electrode close to an axis of rotation of the first electrode. In this device, a corona discharge zone is formed between the two electrodes towards a periphery of the first electrode. Rotation of the first electrode induces rotation of a compressor having an impeller that generates centrifugal force causing the water to flow under pressure through the corona discharge zone. These devices required that an air gap, typically between 1 to 3 mm, be maintained between the liquid-gas interface and the ionizing electrode in order to form the corona discharge zone. If a closed reactor is tilted relative to the horizontal by even as little 30° during operation, the force of gravity acting on the water surface, causes the water to fill the air gap, which prevents maintenance of the corona discharge and renders the device inoperable. Therefore, such devices cannot be used where the reactor is subject to tilting, for example, in applications such as air conditioners and refrigerators in vehicles or airplanes.

[0008] Other drawbacks of known devices relate to design complexity, as well as bulk dictated by the provision of separate chambers for water and hydrogen peroxide.

[0009] SUMMARY OF THE INVENTION

[0010] The present invention addresses some of the drawbacks of known devices by conveying water through a narrow tube at sufficient pressure to create a high-pressure jet that emerges from the end of the tube and retains its form regardless of an angular displacement of the tube from an initial orientation within a prescribed limit. The high- pressure jet is conveyed through an air gap in which there is created a positive polarity corona discharge zone so as to generate hydrogen peroxide (H2O2).

[0011] To this end, there is provided in accordance with the invention a method and device for producing hydrogen peroxide (H2O2) having the features of the respective independent claims.

[0012] A method according to the invention comprises disposing an elongated nonionizing electrode inside a tube such that a length of the non-ionizing electrode protrudes from an end of the tube; disposing an ionizing electrode in spaced relationship with the non-ionizing electrode so as to form an air gap between the ionizing electrode and the length of the non-ionizing electrode protruding from the end of the tube; applying high voltage DC across the ionizing electrode and the non-ionizing electrode so as to create a positive polarity corona discharge zone in said air gap; and conveying water through the tube at sufficient pressure to create a high-pressure jet that emerges from the end of the tube and passes through the corona discharge zone without fouling the air gap regardless of an angular displacement of the tube from an initial orientation within a prescribed limit. The minimum pressure required to form a jet may be established experimentally, taking into account the diameter of the tube, its length, the diameter and length of the non-ionizing electrode protruding from the end of the tube and the maximum allowable angular displacement.

[0013] In some embodiments, the water is stored in a reservoir and the hydrogen peroxide is recycled to the same reservoir so as to constantly increase concentration of hydrogen peroxide in the reservoir. When a sufficient concentration of hydrogen peroxide is formed, it may be syphoned off either manually or automatically, thus obviating the need for a separate chamber to store hydrogen peroxide.

[0014] Prolonged application of corona discharge in the air gap through which the jet is conveyed, heats the liquid hydrogen peroxide, which transfer the heat through the device during successive recycling of the hydrogen peroxide. At high temperature, the hydrogen peroxide decomposes to form water and oxygen and resulting reduction in the surface tension of the liquid impacts negatively on the formation and maintenance of the jet.

[0015] Therefore, in accordance with some embodiments, one or more cooling elements is provided for removing heat from at least one of the liquid channels.

[0016] Other features and advantages will become apparent from the detailed description.

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0019] Fig. 1 shows schematically a device for producing hydrogen peroxide according to an embodiment of the invention;

[0020] Fig. 2 is an enlarged detail of the electrode configuration shown in Fig. 1;

[0021] Figs. 3a and 3b are elevation and cross-sectional views of an alternative electrode configuration; and

[0022] Fig. 4 is a flow diagram showing principal operations of a controller for controlling the device. DETAILED DESCRIPTION OF EMBODIMENTS

[0023] In the following description of some embodiments, identical components that appear in more than one figure or that share similar functionality will be referenced by identical reference symbols.

[0024] Fig. 1 shows schematically a device 10 comprising a reservoir 11 for containing an initial volume of water that is conveyed under pressure through a tube 13 having an open end 14. An elongated non-ionizing electrode 15 is disposed inside the tube 13 such that a length 16 of the non-ionizing electrode 15 protrudes from the end 14 of the tube. An ionizing electrode 17 is disposed in spaced relationship with the non-ionizing electrode 15 so as to form an air gap 18 between the ionizing electrode and the length 16 of the non-ionizing electrode protruding from the end 14 of the tube. The tube 13, the non-ionizing electrode 15 and the ionizing electrode 17 together form a reactor 20 shown in dashed line, in which liquid is converted to hydrogen peroxide. Electrical contacts 21, 2T coupled to the non-ionizing electrode 15 and the ionizing electrode 17 serve to connect across the electrodes a source 23 of high voltage DC. The high voltage DC source has terminals 24, 24' for connecting to a source of electrical power such as an AC mains power supply (not shown) and is of sufficient magnitude (typically in the range of 3kV to lOkV) to create a positive polarity corona discharge zone 25 in the air gap 18, whereby water passing through the corona discharge zone is converted to hydrogen peroxide. A liquid pump compressor 26 having electrical contacts 27, 27' for connecting to a source of electrical power such as an AC mains power supply (not shown) conveys liquid from the reservoir 11 under pressure through the tube 13 to create a high-pressure jet 28 that emerges from the end 14 of the tube 13 and passes through the corona discharge zone 25. Dimensions of the tube 13, the non-ionizing electrode 15, the air gap 18 and the pressure are selected so as to maintain the form of the jet without fouling the air gap regardless of an angular displacement of the tube from an initial orientation within a prescribed limit. In a prototype of the device constructed by the inventor, the internal diameter of the tube was 2.5mm, the diameter of the non-ionizing electrode 15 was 1mm, and the width of the air gap was 2mm. A commonly available miniature 12V DC brushless liquid pump having a nominal power rating of 4.8W and a flow rate of 240 liter / hour produced sufficient pressure to displace the device through an angle of 45° without the liquid jet fouling the air gap and shorting the non-ionizing electrode 15. In practice, the liquid pressure may be adjusted by varying the angular speed of the pump’s impeller, which may be achieved by varying the voltage. However, if required according to where the device is intended for use, the air gap and / or pressure may be increased to allow the device to be displaced through 90°, while maintaining the desired design criteria.

[0025] It is emphasized that these parameters are provided by way of non-limiting example. In practice, the minimum pressure required to form a jet may be established experimentally, taking into account the diameter of the tube, its length, the diameter and length of the non-ionizing electrode protruding from the end of the tube and the maximum allowable angular displacement. The tube diameter affects pressure because the electrode reduces the effective cross-sectional area of the jet, such that the larger the diameter of the electrode for a tube of given cross-section, the higher will be the pressure. Length is important because the length the portion of the non-ionizing electrode protruding from the end of the tube impacts the length of the reactor 20. The pressure must be sufficient to maintain the initial orientation of the jet along the entire length of the reactor 20, including the length of the tube for forming the liquid jet and the length of the nonionizing electrode protruding from the tube, when the ionizing electrode is made in accordance with Figs. 1 and 2.

[0026] In a prototype of the device, the reservoir 11 has an inlet 30 for adding water and an outlet 31 for discharging water or hydrogen peroxide solution through a first channel 32 to which the compressor 26 is fluidly coupled, the compressor outlet being fluidly coupled to a second channel 33. A controllable fluid diverter 35 has an inlet 36 that is coupled to a distal end of the second channel 33 and is selectably couplable to either a circulation port 37 or to a release outlet 38. The circulation port 37 is fluidly coupled to the tube 13 via a third channel 40. In normal operation, the fluid diverter 35 is configured such that the inlet 36 is fluidly coupled to the circulation port 37, whereby liquid is pumped under pressure by the compressor 26 from the reservoir 11 through the third channel 40 from which it is forced as the high-pressure jet 28 through the tube 13. The high-pressure jet 28 emerges from the tube 13 into the air gap 18, causing it to enter the corona discharge zone 25, which converts it to hydrogen peroxide. The end 14 of the tube 13 is located in spaced relationship with the reservoir 11 such that the hydrogen peroxide is recycled into the reservoir through an opening 41 so as to constantly increase concentration of hydrogen peroxide in the reservoir. A controller 45 has a pair of power terminals 46, 46' for coupling to a source of power (not shown) and is responsive to a sensor signal 47 indicative of corona discharge current and to a control signal 48 for controlling operation of the device. To this end, a first output 50 of the controller 45 is fed to the compressor 26 for adjusting pressure, and a second output 51 of the controller 45 is fed to the fluid diverter 35. This allows the controller to actuate the fluid diverter 35 automatically for initially coupling the inlet 36 to the circulation port 37 and subsequently to the release outlet 38, whereby under the action of the compressor 26, hydrogen peroxide solution in the reservoir 11 is discharged for collection. Alternatively, the controller may be omitted in which case the fluid diverter 35 needs to be adjusted manually. In either case, the fluid diverter can be a simple tap or valve fluid coupled to the reservoir either directly or via the compressor.

[0027] In some embodiments, the controller 45 measures elapsed time after applying a first control signal to the fluid diverter 35, consequent to which the inlet 30 thereof is fluidly connected to the circulation outlet 37. After a predetermined elapsed time corresponding to a sufficient number of cycles producing a required concentration of hydrogen peroxide, the controller 45 applies a second control signal to the fluid diverter 35 for fluidly connecting the inlet 36 to the release outlet 38. The compressor 26 now pumps hydrogen peroxide solution from the reservoir 11 through the release outlet 38 for periodically siphoning off when the hydrogen peroxide solution reaches a sufficient concentration. The reservoir 11 is filled with fresh water via the inlet 30 after draining the accumulated hydrogen peroxide solution. The inlet 30 may be filled manually or via an electrically operated valve (not shown) under control of the controller 45. Alternatively, the concentration of the hydrogen peroxide solution may be monitored and the controller 45 can then be programmed to change the connections of the fluid diverter 35 when the concentration reaches a predetermined level.

[0028] In order to obtain the sensor signal 47 indicative of corona discharge current, a resistor 53 having a first end 54 coupled to the negative output of the high voltage DC power supply and a second end 55 commonly coupled to the non-ionizing electrode 15 and GND whereby corona discharge current flows through the resistor 53. The sensor signal 47 indicative of corona discharge current is measured as a function of the voltage across the resistor 53. The controller 45 is responsive to excessive or insufficient current for producing a fault signal, which may then activate an alarm. Alternatively, the input or output current of the high-voltage source can be used to indicate a fault in the operation of the main components of the device, such as the high- voltage source, compressor, or liquid flow switch. Indeed, the absence of liquid in the reactor or a decrease in the high-voltage value leads to a decrease in the input or output current of the high-voltage source. To this end, the sensor signal 47 indicative of excess current may be measured as a function of the current flowing through a resistor 56 connected to the HV terminal 21. The controller 45 is responsive to excessive or insufficient current for producing a fault signal, which may then activate an alarm.

[0029] When water is conveyed under pressure through an open tube to form a jet, temperature has a significant effect on surface tension, which in turn influences the stability and shape of the jet. At high temperatures, the jet may spread or flare more after exiting the end the tube, and droplets at the end of the jet may form more readily. These effects may be mitigated by providing in association with the first channel 32 and / or the third channel 40 a respective cooling element 60 having electrical contacts 61, 6T for connecting to a source of electrical power such as an AC mains power supply (not shown) for cooling liquid during recycling. This has the effect to reduce surface tension of the jet emerging from the tube thereby maintaining its stability.

[0030] A malfunction may lead either to a change in the corona discharge current or to its disappearance. For example, problems in the operation of the compressor 26, leading to the absence of liquid in the device or a significant decrease in liquid pressure, cause an increase in the air gap between the non-ionizing and ionizing electrodes, and, as a consequence, to a decrease in the corona discharge current. This can be seen from Fig. 1 where the air gap corresponds to the space between the outer surface of the liquid jet 28 and the ionizing electrode 17. However, if owing to malfunction, the liquid jet recedes or its outer diameter reduces, then the air gap will increase. In the event of a complete loss of pressure, the air gap will be maximum corresponding to the space between the two electrodes. Similarly, a malfunction in the high-voltage source 23 itself will be registered by the sensor signal 47, in responsive to which the controller may provide an audible or visual alarm.

[0031] In the arrangement shown in Fig. 1, the ionizing electrode 17 is of generally elongated form that is spaced apart from the non-ionizing electrode 15 and generally parallel thereto, and has an active portion 65 of sawtooth shape, which provides several local ionization teeth 66 disposed normal to the non-ionizing electrode, as shown in enlarged view in Fig. 2. At each tooth 66, localized plasma channels called streamers are formed that rapidly extend from the corona discharge zone into the air gap. The longer the active portion 65, the more teeth can be accommodated, thereby reducing the ionizing current at each tooth, which operates as a micro-electrode.

[0032] Figs. 3a and 3b are elevation and cross-sectional views of an alternative electrode configuration wherein the ionizing electrode 17 is in the form of an electrically conductive ring that surrounds the non-ionizing electrode 15. The plane of the ring is thus normal to the non-ionizing electrode 15. The internal diameter of the ring is larger than the external diameter of the non-ionizing electrode 15, thus creating an annular air gap 18 across which a corona discharge zone is formed.

[0033] Fig. 4 is a flow diagram showing operation of the device. First, the reservoir 11 is filled with water through the inlet 30. The controller 45 sends an actuation signal to the compressor 26 and a first control signal to the fluid diverter 35, whose input 36 is thereby fluidly connected to the circulation outlet 37. The controller 45 likewise actuates the high voltage source 23 thereby forming a corona discharge zone 25 in the air gap 18. The compressor 26 pumps liquid 70 from the reservoir 11 via the channels 32, 33 and 40 through the tube 13 thus forming the high pressure jet 28, which is converted into H2O2 when it passes through the corona discharge zone 25 and then re-enters the reservoir 11 through opening 41, completing the recycling path. During each cycle, the concentration of H2O2 in the reservoir 12 progressively increases according to a linear law. After a given time, the controller 45 sends a second control signal to the liquid distributor 35, whose input 36 is thereby fluidly connected to the release outlet 38 and hydrogen peroxide solution may be drained from the reservoir 11. After a further period of time sufficient for the compressor to remove all the hydrogen peroxide solution from the reservoir 11, the controller 45 switches the fluid diverter 35 back to its operative position.

[0034] In a prototype of the device having the following technical specification, it was found that operation remained unimpaired even upon rotation of the device through as much as 90°, thereby changing the orientation of the non-ionizing electrode 16 from vertical (as shown in Fig. 1) to horizontal.

Claims

CLAIMS:

1. A method for producing hydrogen peroxide (H2O2), the method comprising: disposing an elongated non-ionizing electrode inside a tube such that a length of the non-ionizing electrode protrudes from an end of the tube; disposing an ionizing electrode in spaced relationship with the non-ionizing electrode so as to form an air gap between the ionizing electrode and the length of the non-ionizing electrode protruding from the end of the tube; applying high voltage DC across the ionizing electrode and the non-ionizing electrode so as to create a positive polarity corona discharge zone in said air gap; and conveying water through the tube at sufficient pressure to create a high-pressure jet that emerges from the end of the tube and passes through the corona discharge zone without fouling the air gap regardless of an angular displacement of the tube from an initial orientation within a prescribed limit.

2. The method according to claim 1, wherein the pressure at which the water is conveyed through the tube is sufficient to maintain a unform cross-section of the jet when the tube is tilted from an initial position through at least 45°.

3. The method according to claim 1 or 2, including determining the pressure experimentally in accordance with a selected diameter and length of the tube, diameter of the non-ionizing electrode, the length of the non-ionizing electrode protruding from the end of the tube, and a selected maximum allowable angular displacement.

4. The method according to any one of the preceding claims, including conveying water through the tube from a reservoir and recycling hydrogen peroxide to the reservoir so as to constantly increase concentration of hydrogen peroxide in the reservoir.

5. The method according to claim 4, including cooling the water during recycling to reduce surface tension of the water jet and maintain its stability.

6. The method according to any one of the preceding claims, including monitoring corona discharge current to indicate faults.

7. The method according to any one of the preceding claims, including monitoring input or output HV current to indicate faults.

8. A device (10) for producing hydrogen peroxide (H2O2), the device comprising: a reservoir (11) for containing an initial volume of water (70), a compressor (26) for conveying liquid from the reservoir under pressure through a tube (13), an elongated non-ionizing electrode (15) disposed inside the tube (13) such that a length (16) of the non-ionizing electrode protrudes from an end (14) of the tube, an ionizing electrode (17) in spaced relationship with the non-ionizing electrode so as to form an air gap (18) between the ionizing electrode and the length (16) of the non-ionizing electrode protruding from the end of the tube, and a pair of contacts (21, 21') for connecting across the ionizing electrode and the non-ionizing electrode a source of high voltage DC (23) of sufficient magnitude to create a positive polarity corona discharge zone in the air gap whereby water passing through the corona discharge zone is converted to hydrogen peroxide; the compressor being configured to convey liquid through the tube at sufficient pressure to create a high-pressure jet that emerges from the end of the tube and passes through the corona discharge zone without fouling the air gap regardless of an angular displacement of the tube from an initial orientation within a prescribed limit.

9. The device according to claim 8, wherein the compressor is configured to convey liquid through the tube at sufficient pressure to maintain a unform cross-section of the jet when the tube is tilted from an initial position through at least 45°.

10. The device according to claim 8 or 8, including at least one cooling element (60) for cooling liquid during recycling to reduce surface tension of the jet emerging from the tube and maintain its stability.

11. The device according to any one of claims 8 to 10, including a controller (45) for controlling operation of the device.

12. The device according to claim 11, including a sensor (53) for monitoring corona discharge current and being responsive to excessive or insufficient current for producing a fault signal.

13. The device according to claim 12, wherein the sensor includes a current collecting resistor (53) connected at a first end to the non-ionizing electrode and ground and connected at a second end to the low-voltage terminal of the high-voltage DC source.

14. The device according to any one of claims 11 to 13, including a sensor (56) for monitoring current flow to or from the source of high voltage DC (23) and being responsive to excessive or insufficient current for producing a fault signal.

15. The device according to any one of claims 12 to 14, wherein the controller is responsive to the fault signal for actuating an alarm.

16. The device according to any one of claims 11 to 15, wherein: the end (14) of the tube is located in spaced relationship with the reservoir (11) such that hydrogen peroxide is recycled into the reservoir so as to constantly increase concentration of hydrogen peroxide in the reservoir, and a fluid diverter (35) is fluidly coupled to the reservoir and is operable for draining hydrogen peroxide accumulated in the reservoir through a release outlet (38).

17. The device according to claim 16, wherein the fluid diverter is operatively coupled to the controller and responsive to a control signal for either circulating pressurized liquid from the compressor (26) through the tube (13) or for draining hydrogen peroxide through the release outlet (38).

18. The device according to any one of claims 8 to 17, where the ionizing electrode (17) is of generally elongated form that is spaced apart from the non-ionizing electrode (15) and generally parallel thereto, and has an active portion (65) supporting multiple teeth (66) that are disposed normal to the non-ionizing electrode.

19. The device according to any one of claims 8 to 17, wherein: the ionizing electrode (17) is in the form of an electrically conductive ring that surrounds the non-ionizing electrode (15), such that a plane of the ring is normal to the non-ionizing electrode (15); and an internal diameter of the ring is larger than an external diameter of the nonionizing electrode (15), thus creating an annular air gap (18).

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