WO1999037581A2 - Systeme a haut rendement de traitement de gaz par decharge luminescente pour la production de peroxyde d'oxygene et autres traitements chimiques de gaz - Google Patents

Systeme a haut rendement de traitement de gaz par decharge luminescente pour la production de peroxyde d'oxygene et autres traitements chimiques de gaz Download PDF

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WO1999037581A2
WO1999037581A2 PCT/US1999/000911 US9900911W WO9937581A2 WO 1999037581 A2 WO1999037581 A2 WO 1999037581A2 US 9900911 W US9900911 W US 9900911W WO 9937581 A2 WO9937581 A2 WO 9937581A2
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discharge
gas
magnetic
discharge volume
process gas
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PCT/US1999/000911
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WO1999037581A3 (fr
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William M. Moeny
David M. Barrett
Robert W. Bennett
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Moeny William M
Barrett David M
Bennett Robert W
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Priority to AU22309/99A priority Critical patent/AU2230999A/en
Publication of WO1999037581A2 publication Critical patent/WO1999037581A2/fr
Publication of WO1999037581A3 publication Critical patent/WO1999037581A3/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
    • B01J19/122—Incoherent waves
    • B01J19/123—Ultraviolet light
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/087—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J19/088—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
    • B01J19/122—Incoherent waves
    • B01J19/125—X-rays
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
    • C01B13/10—Preparation of ozone
    • C01B13/11—Preparation of ozone by electric discharge
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B15/00—Peroxides; Peroxyhydrates; Peroxyacids or salts thereof; Superoxides; Ozonides
    • C01B15/01—Hydrogen peroxide
    • C01B15/027—Preparation from water
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
    • B01J2219/0809—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes employing two or more electrodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
    • B01J2219/0824—Details relating to the shape of the electrodes
    • B01J2219/0826—Details relating to the shape of the electrodes essentially linear
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
    • B01J2219/0824—Details relating to the shape of the electrodes
    • B01J2219/0826—Details relating to the shape of the electrodes essentially linear
    • B01J2219/083—Details relating to the shape of the electrodes essentially linear cylindrical
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0845—Details relating to the type of discharge
    • B01J2219/0847—Glow discharge
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0873—Materials to be treated
    • B01J2219/0875—Gas
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2201/00—Preparation of ozone by electrical discharge
    • C01B2201/80—Additional processes occurring alongside the electrical discharges, e.g. catalytic processes
    • C01B2201/82—Treatment with ultraviolet light
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2201/00—Preparation of ozone by electrical discharge
    • C01B2201/80—Additional processes occurring alongside the electrical discharges, e.g. catalytic processes
    • C01B2201/84—Treatment with magnetic fields

Definitions

  • the invention relates generally to glow discharge methods and apparatus for processing gases into useful products. More particularly, it relates to a glow discharge apparatus having magnetic switching to provide fast rise-time voltage pulses, and employing radial discharge and high pressure in the production of commercially valuable product gases such as ozone and hydrogen peroxide.
  • Glow discharges provide a convenient means for processing gases or mixtures of gases to produce new compounds.
  • the ability of the glow discharge to initiate specific chemical reactions, due to the control of the electron energy distribution in the weakly ionized plasma, is a major advantage over conventional thermal discharges.
  • a glow discharge chemical processor can achieve many of the effects of thermal processing but does so by heating only the electron swarm and not the complete gas mixture.
  • Glow discharges comprised of weekly ionized plasmas are widely used for pumping pulsed C0 2 lasers and excimer lasers, for example.
  • Glow discharges differ from other types of discharges in that the discharge is diffuse. Namely, the current in the discharge is uniformly distributed throughout a volume of gas to be processed or excited.
  • the discharges are weakly ionized with typical ionization fractions of 0.1 to 1 PPM. Because the gas is very weakly ionized, almost all of the collisions by electrons will be with neutrals. As a result, the characteristics of the electron swarm are dominated by these collisions. Also, the average energy of the electrons is typically quite low, on the order of 1 electron volt.
  • glow discharges typically operate at atmospheric pressure, however, some operate at pressures as low as 0.1 atmospheres and others operate at pressures as high as 5 atmospheres.
  • the free electrons and ions that conduct the current are created from within the discharge, either by an external source or by the discharge itself.
  • the distinction between these two types of discharges, self-sustained and externally sustained, is important to the present invention. An externally-sustained discharge is much easier to operate because it can be kept much more stable.
  • a glow discharge is very complex, with hundreds of plasma chemistry interactions occurring simultaneously.
  • the interactions can be grouped into four types of processes.
  • the first type is electron attachment.
  • an electron can be captured by a constituent of the gas. For example, if there is oxygen in the gas mixture, an oxygen molecule might capture an electron in the reaction 0 2 + e " > 0 2 ' .
  • the rate of attachment is proportional to the number of electrons and is characterized by the term "b," which is the number of attachments per second per electron. As expressed in Equation 1 below, the loss of electrons due to attachment is equal to the electron number density times the number of attachments per electron per second.
  • the second type of process occurring in the gas mixture is recombination, where an electron and an ion recombine.
  • Recombination is characterized by the term "g," which is the number of recombinations that occur per second per electron per ion.
  • g the number of recombinations that occur per second per electron per ion.
  • the ion number density is approximately the same as the electron number density.
  • Equation 3 expresses the ionization phenomena as a function of "a" :
  • the fourth type of process ocurring in the gas mixture is that an electron will collide with a neutral and will give up some energy to the neutral, thereby changing the energy state of the neutral, but neither ionizes the neutral nor is attached to it (recombination only occurs with ions).
  • the electron number density changes with time according to whether the ionization, attachment, or recombination process dominates. This is described by Equation 4 below:
  • Equation 4 can be used to describe two regimes of discharge operation. For most discharges of interest to chemical processing and gaseous lasers, recombination is not a significant process because the attachment rate is very high and dominates the discharge loss processes (for discharges operating near 1 atmosphere). In this case, whether the electron density increases or decreases depends upon whether the ionization coefficient, a, is greater than or less than the attachment coefficient, b.
  • FIG. 1 is a plot of the relative attachment and ionization coefficients for a typical pulsed C0 2 laser mixture. As FIG. 1 shows, at a lower normalized electric field (the electric field normalized to the neutral number density, i.e., essentially the electric field per molecule), the attachment rate is much higher than the ionization rate.
  • discharge collapse is the principle phenomena leading to limitation on the amount of energy that can be put into the gas by the glow discharge. As mentioned, there are two primary regimes of operation of a glow discharge: externally-sustained and self-sustained.
  • the externally-sustained discharge is the electric field regime where the attachment coefficient is larger than the ionization coefficient. As shown from Equation 4, without the external supply, the electron number density will continually decay and eventually, on a time scale set by the difference between the attachment and the ionization coefficients, the discharge will extinguish through lack of electrons. In an externally-sustained discharge, the external sustainer device makes up the electrons lost to attachment.
  • An electron beam gun might be utilized to inject high energy electrons into the discharge region, as shown, for example, in U.S. Patent
  • a self-sustained discharge the electrons are provided by the ionization process in the discharge.
  • the electrons avalanche to a steady-state condition where the ionization and attachment rates are equal.
  • This electric field is commonly called the glow field or glow point.
  • the glow field the electron number density is neither increasing nor decreasing.
  • For a discharge to successfully operate at this point requires an external circuit control of some type, such as a pulse forming network. It is very difficult to operate a glow discharge in the self-sustained mode because the electric fields have to be very uniform and the discharge has to be uniformly initiated for it to operate without collapsing into an arc.
  • the foregoing explains the difference between the externally-sustained discharge and the self-sustained discharge.
  • the externally-sustained discharge is easier to realize in practice because the electron number density is controlled by the external discharge sustainer device, such as an electron beam gun, and thus electron number density can be controlled somewhat independently of the electric field.
  • the electric field can be kept well below the glow point, reducing the chance for discharge collapse due to avalanche runaway.
  • the self-sustained discharge is much more difficult to operate because it is a balancing act; the discharge being balanced very carefully between excessive ionization and excessive attachment. It is especially difficult to do with a highly attaching gas mixture.
  • Externally-sustained and self-sustained discharges have traditionally been utilized for pumping molecular gas lasers such as pulsed electric C0 2 lasers and excimer lasers.
  • the self-sustained devices have all utilized linear electrodes, that is, where the discharge region is formed between two plane parallel, long, narrow electrodes to provide a long gain-path for the laser.
  • the C0 2 laser gas mixture is typically composed of carbon dioxide, nitrogen, and helium. There are no strong attachers in this gas mixture.
  • Self-sustained discharges in these mixtures have proven to be fairly reliable and commercially are used extensively. The introduction of a small amount of oxygen, however, can create significant discharge instability with these devices because of the high attachment rate of oxygen.
  • Excimer lasers that utilize small quantities of halogens such fluorine or chlorine have also been successfully operated using either externally-sustained or self-sustained discharges. These discharges typically operate with very short pulses and the total amount of halogen present is kept very small because the high attachment rate of the halogens tends to cause the discharge to be unstable, just as oxygen does.
  • Ozone is an unstable triatomic compound of oxygen and is used in a number of applications, such as water treatment, industrial effluent treatment, and industrial bleaching operations. Since ozone is an unstable compound, decomposing back to diatomic oxygen after a short while, it is necessary to generate ozone at its point of use. Ozone is formed by using an electrical discharge to dissociate diatomic oxygen molecules into single atoms, which subsequently combine with other diatomic oxygen molecules to form ozone. In most conventional ozone generators, commonly referred to as ozonators, the electrical discharge is developed in a dielectric barrier discharge, also referred to as a silent discharge configuration.
  • a silent discharge can be configured in a coaxial or planar geometry and typically consists of a pair of electrodes that are excited with a relatively high voltage alternating current waveform. One or perhaps both electrodes are covered with a dielectric material such as glass or ceramic. Typically, a sinusoidal or bipolar pulsed high voltage waveform is impressed across the electrode pair to generate an electric field in the discharge gap of the silent discharge configuration. When the breakdown electric field of the gas molecules between the electrodes is reached, the gas becomes partially ionized. Specifically, the ionization of the gas proceeds as a multiplicity of microdischarges are formed between the dielectric barrier and an electrode. As each microdischarge is formed, it conducts electrical charge through the gas volume that accumulates on the surface of the dielectric barrier.
  • the charge As charge continues to be conducted through the gas volume, the charge accumulates on the surface of the dielectric barrier and reduces the local electric field. As a result, the microdischarge is extinguished and another microdischarge is developed at another location. Thus, the multiplicity of microdischarges are semi-uniformly distributed throughout the gas volume.
  • Each microdischarge serves as a source of energetic electrons, which are necessary for the production of ozone. Electrons having sufficient energy ( > 6 eV), collide with diatomic oxygen molecules causing them to dissociate and form singlet oxygen atoms. The singlet atoms subsequently combine with other diatomic oxygen molecules to form ozone.
  • the efficiency at which ozone is produced in practice is limited to approximately 12%. There are a number of factors that contribute to this low efficiency.
  • the discharge in a silent discharge configuration is formed as a group of individual microdischarges that are semi-uniformly distributed throughout the gas volume.
  • the gas volume that is actually exposed to the electrical discharge at any given time is a fraction of the total gas volume that occupies the discharge region. Therefore, the dynamics necessary for the formation of ozone are restricted to a small portion of the total gas volume.
  • silent discharges are typically excited with high voltage waveforms that have a relatively low voltage- rate-of-rise (e.g., ⁇ 100 V/ns). At these values, the ignition voltage of the discharge gap is relatively low, resulting in the production of electrons having an average energy of less than 6 eV. Therefore, the majority of electrons do not attain the energy needed to dissociate diatomic oxygen.
  • the ozone production efficiency of conventional silent discharge configurations is limited by the poor heat transfer characteristics of the geometry. Specifically, the rate at which ozone dissociates is accelerated as the temperature of the process gas is increased.
  • ozone In a conventional silent discharge configuration, the electrodes are typically water-cooled; however, the flow rate of the process gas through the discharge cell is relatively low. Therefore, because the principal heat transfer mechanism between the process gas and the wall-cooled electrode is conduction, a large electrode area is required to provide the required heat transfer. It has been determined that ozone can be generated with efficiencies exceeding 25%. Significantly improved ozone generation efficiencies may be achieved by exciting an electrical discharge with high voltage pulses having a voltage rate-of-rise in excess of 500 V/ns. In addition, using high voltage pulses having such a voltage-rate-of-rise enables ozone to be generated in a bulk glow discharge configuration, which does not require a dielectric barrier.
  • Some high performance pulsed C0 2 laser devices in use employ trace hydrocarbon additives to enhance discharge stability.
  • one of the principle requirements for successful initiation and control of a self-sustained pulsed discharge is uniform initiation of the discharge. This requires the creation of an initial background of electrons uniformly distributed across the discharge region and of a number density well above any non-uniformities caused by stray cosmic rays or other ionizing sources.
  • hydrocarbon photoelectron seedants By putting hydrocarbon photoelectron seedants into the gas mixture, it is possible to create a much higher density of photoelectrons than would be created without seedants. Seedants also can be used to depress the glow electric field by increasing the ionization rate at a specific electric field. The equilibrium point where the ionization rate matches the attachment rate can be reduced, thereby increasing discharge stability.
  • U.S. Patent No. 5,554,345, entitled "Ozone Generation Apparatus and Method" to Kitchenman, O. S. G., discloses a dielectric barrier apparatus for the generation of ozone that is an improvement upon the conventional dielectric barrier ozone generator.
  • Kitchenman's system uses a conventional electrical supply having a frequency of at least 20 kHz.
  • Kitchenman does not teach the use of recirculating the ozone to increase concentration while decreasing temperature rise and does not teach the use of magnetic switching or UV preionization for the bulk discharge for the generation of ozone.
  • Kitchenman does not disclose the use of a bulk glow discharge for ozone generation.
  • This method does not teach the use of magnetic switches for controlling the discharge and does not teach the use of a bulk glow discharge, but rather, teaches the use of a dielectric barrier discharge.
  • Yokomi does not teach the use of recirculating the gas to control temperature nor does it teach the use of magnetic switches for generating the pulse to the electrodes.
  • the glow discharge is externally sustained.
  • the electric field is pulsed on during the electron beam irradiation and thereafter pulsed off to maximize energy deposition by electrons and minimize energy deposition by ions.
  • Douglas-Hamilton does not teach the use of UV preionization or any type of preionization since the electron beam provides all ionization.
  • the present invention does not utilize an E-type pulse forming line for controlling the shape of the output pulse.
  • U.S. Patent No. 3,856,671 entitled “Closed Loop Ozone Generating and Contacting System” by Lee, H., et al., indicates the use of a closed loop system for treating water with ozone and/or oxygen, thus conserving the high oxygen content gas.
  • the system comprises a method of utilizing oxygen-enriched gas contacted with water to be treated.
  • the excess oxygen and/or oxygen and nitrogen forms a recycled gas which is combined with a charge of air and flowed to another apparatus for recirculating the oxygen for subsequent use.
  • the present invention utilizes a recirculation system for controlling the temperature rise in oxygen containing gaseous mixtures or other chemical mixtures that are being processed by a glow discharge.
  • the present invention overcomes the deficiencies associated with the prior art of gaseous chemical processing by providing a novel homogeneous bulk glow discharge apparatus and method.
  • an apparatus for converting a process gas into a product gas includes anode and cathode electrodes that define a discharge volume between the electrodes such that the discharge volume contains at least some of the process gas.
  • a magnetic pulse compression network having at least one magnetic switch, is coupled to the electrodes and provides fast rise-time high voltage pulses to the electrodes and the discharge volume. The fast rise-time high voltage pulses, when impressed across the discharge volume, produce a self-sustaining glow discharge that converts at least some of the process gas into the product gas.
  • the magnetic pulse compression network includes a coupled network of magnetic switches and charge storage elements that are arranged in stages so that the magnetic switches couple between the charge storage elements of the stages.
  • Each of the stages receives a voltage pulse having a first rise-time and produces an output pulse having a second rise-time less than the first rise-time.
  • the magnetic pulse compression network is adapted to impress a series of fast rise-time high voltage pulses across the discharge volume such that each successive pulse from the series of voltage pulses has less energy density than the previous pulse.
  • a pre-ionizer pre-ionizes the process gas.
  • a gas circulation system conveys process gas to the discharge volume and removes product gas from the discharge volume.
  • a heat exchanger is preferably included to remove heat from the process gas and the product gas.
  • a method of converting a process gas into a product gas conveys the process gas into a discharge volume that is defined between a cathode electrode and an anode electrode.
  • the process gas within the discharge volume is pre-ionized.
  • a magnetic modulator network having at least one magnetic switch generates a fast rise-time high voltage pulse and couples it to the electrodes.
  • a self-sustaining glow discharge is produced in the discharge volume and at least some of the process gas is converted into the product gas.
  • the process gas and the product gas are circulated through a heat exchanger.
  • the discharge volume is pressurized to a pressure greater than atmospheric pressure.
  • FIG. 1 is a graphical representation of the known attachment and ionization rate coefficients divided by the electron drift velocity for a glow discharge in 0 2 ;
  • FIG. 2 is a block diagram of a high efficiency bulk discharge processing system according to one embodiment of the invention.
  • FIG. 3 is a graph depicting the temporal relationships between the preionizer voltage pulse, the main discharge voltage pulse and the electron number density (n e ) of the discharge according to the invention
  • FIG. 4A is a top sectional view of the discharge assembly according to an embodiment of the invention including a plurality of rectangular ceramic blocks to form the dielectric barrier for the preionization subassembly;
  • FIG. 4B is a partial sectional view, taken along line X--X in Fig. 4A, of the embodiment shown in Fig. 4A, with a portion broken away to reveal certain internal components;
  • FIG. 5A is a top sectional view of another embodiment of the invention, showing a discharge assembly incorporating a single piece of ceramic material to form the dielectric barrier for the preionization subassembly;
  • FIG. 5B is a partial sectional view, taken along line Y--Y of Fig. 5A, of the embodiment shown in Fig. 5A;
  • FIG. 6 is a diagram of the inventive apparatus with its accompanying process gas circulation system
  • FIG. 7 is a cross sectional view of an alternative radial discharge embodiment of the invention, showing a concentrically arranged discharge electrode array and preionizers;
  • FIG. 8 is a is an axial sectional diagram of a portion of the embodiment shown in Fig. 7, illustrating the preionizers in a position transverse to the sides of the discharge volume;
  • FIG. 9 is a radial sectional view of the embodiment shown in Fig. 7, illustrating a radially directed gas flow
  • FIG. 10 is diagram of a system, according to the invention, for the production of hydrogen peroxide
  • FIG. 1 1 is a schematic drawing of a multistage magnetic pulse compression network used to supply fast rise-time, short duration, high voltage pulses to the discharge processing apparatus of the invention
  • FIG. 12 is a graphical depiction of the voltage waveforms on each capacitor in the solid state switched magnetic modulator network, as well as the main high voltage pulse which is impressed across the discharge cell according to the present invention
  • FIG. 13 is a block diagram of a timing and triggering circuit according to the invention.
  • the present invention relates to an apparatus and method for efficiently processing a process gas, such as oxygen, into a product gas or compound, for example ozone, by a homogeneous electrical glow discharge.
  • the glow discharge may be operated at about one atmosphere to produce ozone, for example.
  • the present invention also permits the practical implementation of an above- atmospheric pressure glow discharge configuration for the production, from an oxygen/water vapor process gas mixture, of hydrogen peroxide at high efficiencies.
  • This disclosure describes a new approach to glow discharge processing of gases for a multitude of purposes, while at the same time carefully controlling the temperature of the gases in order to control the overall process rates and functions.
  • one embodiment of the invention includes a discharge assembly or cell, principally including a generally planar cathode electrode and a substantially planar anode electrode.
  • a preionization assembly is connected to the discharge cell, and features an auxiliary electrode and a dielectric barrier proximate to the anode electrode of the discharge cell.
  • Preionization is performed by providing ultraviolet (UV) light or radiation into the glow discharge volume.
  • a power source such as a DC source, powers a source of fast rise-time high voltage pulses, the source chiefly including a command resonance charge circuit in communication with a multi-stage magnetic pulse compression network, which in turn is in communication with the anode electrode and the auxiliary electrode.
  • a modular timing and triggering circuit preferably is provided for controlling the voltage pulse source circuitry. Circulatory system components provide for the recirculation of process and product gases through the discharge cell and through a heat exchanger to maintain the gas flow temperature at desirable process temperatures.
  • Another embodiment of the instant invention for chemical processing is a pulsed radial self-sustained glow discharge at or above atmospheric pressure; all other radial discharges have been operated either externally sustained, continuous operation, at much lower pressure, or for pulsed lasers.
  • pulsed C0 2 lasers it is known to operate pulsed C0 2 lasers at higher pressure, but such operations use an externally-sustained discharge.
  • the early Antares program at Los Alamos national Laboratory ran 5 atmosphere pressure pulsed C0 2 lasers.
  • the radial glow discharge embodiment of the invention uses a self-sustained radial glow discharge, previously utilized only for pumping pulsed C0 2 laser plasmas.
  • the anode and cathode discharge electrodes are concentrically mounted cylinders, with the discharge occurring in the annular volume between the cylinders.
  • the combination of uniform UV preionization illuminating the discharge volume, coupled with a fast-rising, high voltage electric field, and a very carefully controlled electric field distribution enables the use of the radial glow discharge for gas processing in highly attaching gases.
  • the discharge may be used to create ozone from oxygen or create hydrogen peroxide from mixtures of water and oxygen, for example. Other chemicals, such as hydrazine, acetylene, and cyanogen, can also be created with this unique discharge configuration.
  • the self-sustained discharge requires that electrons be initially created in the discharge volume (pre-ionization) in sufficient concentration to overcome electron non-uniformities caused by the passage of stray cosmic rays through the gas mixture. This typically requires preionization levels of approximately 10 9 to 10" electrons per cubic centimeter. These electrons are then avalanched by the electric field to approximately 10 12 to 10 13 electrons per cm 3 to form the glow discharge which processes the gas (the neutral atom/molecule number density at atmospheric pressure is 2.55 x 10 19 per cm 3 at 15 degrees Celsius).
  • a self- sustained discharge can use a UV source pre-ionizer such as an array of raised sparks or a dielectric barrier.
  • a self-sustained glow discharge is a discharge wherein the electrons used for conduction are released from neutral and ionized atoms and molecules by the inelastic collision by other electrons, the ionizing electrons originating either from similar inelastic collisions or from electrons resulting from pre-ionization and accelerated by the electric field between the discharge electrodes.
  • An electron gun (e-gun) could also be utilized for preionization of a self- sustained discharge by creating 10 9 to 10 11 secondary electrons per cm 3 in the discharge. It should be recognized that this is two orders of magnitude less power required from the e-gun than if the discharge were externally sustained by the e- gun.
  • UV source can be utilized, called a "flashboard", wherein the sparks that create the ultraviolet light are formed between metal pads deposited on the surface of a dielectric material such as printed circuit boards.
  • flashboard Another type, called a flashlamp, uses a discharge in low pressure gas such as xenon. The discharge occurs inside an envelope transparent to a significant part of the UV spectrum, such as quartz.
  • the lamps can have high efficiencies, but are only suitable for preionizing certain types of gas mixtures that have a photoelectron process that falls within the transmitted spectrum of the contained discharge.
  • the radial glow discharge configuration is central to commercial applications of the invention because the geometry provides a means for processing all the gas that is flowing through the processor. All of the gas that flows through the apparatus must pass through the glow discharge. There are no electrode ends for the gas to flow around. In known linear devices, because the walls of the discharge chamber must be separated from the ends of the electrodes to avoid surface flashover on the walls, there is always space at the ends of the discharge electrodes through which the process gas can flow, impairing efficiency. Thus, for a commercial glow discharge gas processor, the radial glow discharge is advantageous.
  • the gas processing radial glow discharge is very different from a laser discharge because gases typical for industrial applications have very high attachment rates, such as the oxygen utilized for ozone and peroxide production, for example, and thus require different techniques to operate successfully.
  • the preionizer can be placed in one of three locations.
  • the preionizer can be placed behind the outer electrode, thus flooding the inner electrode with UV light. This is an attractive location because it provides plenty of room for the preionizer.
  • the preionizer can also be located behind the inner electrode, flooding the outer electrode with ultraviolet light. This location is the preferred embodiment of this invention because the relative curvature of the two electrodes provides higher stability conditions when the outer electrode is used as a cathode.
  • the UV light must always flood the cathode for highest performance, self-sustained discharge operation.
  • One version of the radial discharge embodiment employs sidelight emission, that is, sources of ultraviolet light, such as sparks between point electrodes, are arrayed on either side of the main discharge electrodes. When fired, the point electrodes flood the interior of the discharge with ultraviolet light and the discharge receives adequate preionization.
  • sidelight emission that is, sources of ultraviolet light, such as sparks between point electrodes, are arrayed on either side of the main discharge electrodes. When fired, the point electrodes flood the interior of the discharge with ultraviolet light and the discharge receives adequate preionization.
  • the radial glow discharge embodiment of the invention can utilize two types of gas flow. One is axial gas flow, as shown in Fig. 7, where the gas flows between the electrodes parallel to the axis of the cylindrical electrodes. The second is for the gas to flow radially, either out from the inner electrode to the outer electrode or out of the outer electrode to the inner electrode (Fig. 9). This embodiment provides the capability of operating the discharge at high pulse repetition rates.
  • Control of the voltage in time across the electrodes is very important to successful operation of the self-sustained glow discharge for chemical processing.
  • the various embodiments of the present invention may use either magnetic switches, solid-state, or gaseous switches. Magnetic switches are the preferred embodiment. Solid state switches, as well as gaseous switches such as spark gaps, thyratrons, pseudospark switches and other gas switches may also be utilized. Liquid switches, such as water and oil switches are also potential candidates for operating the pulsed self-sustained radial glow discharge for gaseous processing. A key characteristic of all of these switches is that they must produce a rapid electric field rise time to achieve a successful stable operation of the glow discharge for gas processing.
  • the high efficiency system of the invention includes a containment vessel 1 1 , which houses the discharge assembly or cell (16-20), as well as the gas circulation loop 13, a magnetic modulator network 22, including a command resonant charge circuit 23 and a magnetic pulse compression network 21 , provides fast rise-time high voltage pulses to the discharge assembly.
  • a DC power supply 24 provides a constant voltage to the input of the modulator network 22, and a modulator timing and triggering circuit 25 controls the operation of the modulator network 22.
  • a feedstock process gas stream 10 enters the containment vessel 1 1 of the processor.
  • a fan 12 circulates the gas along a looped path 13 preferably including ducts for directing it through the discharge volume 14 into the heat exchanger 15 and returns it to the inlet side of the fan 12.
  • the discharge volume 14 is defined between the anode 18 and the cathode 20.
  • the gas within the discharge volume 14 between the electrodes is preionized by homogeneously illuminating the discharge volume with ultra-violet radiation.
  • the ultra-violet radiation for the preionization is provided by an electrical discharge 16 that occurs between a surface of a dielectric barrier 17 and the anode screen 18.
  • the anode screen 18 is a portion of the anode that is permeable or transparent to ultraviolet light.
  • the ultra-violet radiation produced by the discharge 16 penetrates or passes through the anode screen 18 and into the discharge volume 14.
  • the preionization process is initiated by the application of a high voltage pulse between the anode screen 18 and an auxiliary electrode 19 disposed in contact with the back of the dielectric barrier 17.
  • the discharge volume 14 is excited by the application of the main high voltage pulse, which is impressed across the anode 18 and the cathode 20 electrodes.
  • a homogeneous and stable electrical discharge subsequently ensues in the discharge volume 14 and continues until the main high voltage pulse is terminated.
  • the discharge preionization and excitation process is further illustrated in
  • FIG. 3 where the electron number density 40 of the discharge volume, the preionization voltage pulse 41 , and the main discharge voltage pulse 42 are graphed as a function of time.
  • the electron number density is very low ( “ 10 3 -10 4 electrons/cm 3 ).
  • the preionization voltage pulse 41 is applied to the electrode 19 disposed on the back of the dielectric barrier 17. This causes the volume between the front surface of the dielectric barrier and the anode screen 18 to become partially ionized, thereby producing a significant amount of ultra-violet radiation that penetrates the anode screen 18 and enters and permeates the gas volume 14 between the principal electrodes 18, 20.
  • the UV radiation causes electrons to be freed from the gas molecules within the discharge volume 14 such that the electron number density 40 of the gas volume 14 increases to the order of 10 9 electrons/cm 3 , as shown in FIG. 3.
  • the main high voltage pulse 42 is then impressed across the principal electrodes 18, 20, to act through the discharge volume 14.
  • the high voltage pulses are applied at a voltage rate-of-rise in excess of 500 V/ns.
  • the rapid rise pulses cause a homogeneous electrical discharge to form between the anode 18 and cathode 20 electrodes, which in turn results in a further increase of the electron number density 40 within the discharge volume 14.
  • the electron number density remains at the elevated level until the main voltage pulse 42 is terminated.
  • FIGS. 4A and 4B illustrate a configuration which uses a plurality of ceramic blocks 50 as the dielectric barrier (analogous to barrier 17 in Fig. 2) for the preionization assembly.
  • the cathode 51 and anode 52 electrodes are fabricated from an ozone resistant or other chemical resistant alloy, such as stainless steel or the like.
  • the shapes of the cathode 51 and anode 52 are configured to maintain an uniform electric field within the discharge volume 14.
  • Both the cathode 51 and anode 52 are mounted in respective ones of a pair of electrically non-conductive structures 53, which are used to rigidly support the electrodes 51 , 52 as well as to direct the gas flow through the discharge volume 14 in an efficient manner (i.e., serving as flow transition structures to match a flow cross-section of the discharge volume 14 to a flow cross-section in the ducts).
  • the anode and auxiliary electrode assemblies are secured together with electrically non-conductive standoffs 54, which are used to maintain the precise spacing between the anode 52 and cathode 51 electrodes without interfering significantly with the process gas flow through the volume 14.
  • the anode electrode assembly includes the anode body 52 and the anode screen 18.
  • the anode screen 18, preferably, is a relatively thin piece of perforated stainless steel or other conductive material attached to the anode body 52.
  • the dielectric blocks 50 which serve as the dielectric barrier (generally analogous to barrier 17 in Fig. 2).
  • the dielectric barrier features a plurality of preferably rectangular dielectric blocks 50 mounted end-to-end in order to span the length of the anode electrode assembly.
  • each dielectric block 50 is fashioned from a material such as, but not limited to, ceramic or polymer, having a dielectric constant greater than that of air.
  • each dielectric block 50 is preferably coated with a high-voltage insulating material 58 to prevent electrical breakdown across the surface of the dielectric blocks 50.
  • the face 57 of each dielectric block 50 is appropriately spaced from the anode screen 18 by electrically non-conductive spacers 59 as shown in FIG. 4A.
  • FIGS. 5A and 5B An alternative embodiment of the preionization and electrode assemblies is illustrated in FIGS. 5A and 5B.
  • the anode and cathode structures are similar to those shown in FIGS. 4A and 4B; however, in this configuration, the dielectric barrier is formed with a single piece of machinable dielectric such as, but not limited to, ceramic material 70 which spans the length of the anode electrode assembly.
  • the ceramic (for example) dielectric material 70 is machined into a U-shape as indicated by FIGS. 5A and 5B.
  • An electrically conducting film (not shown) is deposited on the bottom of the ceramic well 71 to which the high voltage preionization pulse is applied.
  • the preionization electrode 72 may be formed by placing an electrically conducting plate on the bottom of the ceramic well 71 and securing it in place with a backfill of epoxy material 73.
  • the face 74 of the ceramic material 70 is appropriately spaced from the anode screen 18 by electrically non-conductive spacers 75 which span the length of the preionizer assembly.
  • a high voltage pulse is applied to the input connections 77 of the preionizer assembly, most of the voltage appears across the gap 76 between the face 74 of the ceramic material 70 and the anode screen 18.
  • the gas in gap 76 is partially ionized and a significant amount of ultra-violet radiation 62 is produced.
  • the ultra-violet radiation penetrates the anode screen 18 as shown in FIG. 5A and impinges upon the gas molecules within the discharge volume 14.
  • the main discharge is subsequently formed when a high voltage pulse is impressed across the anode 52 and cathode 51 electrodes.
  • FIG. 6 A detailed schematic view of the gas circulation system and discharge assembly is shown in FIG. 6.
  • the gas circulation system and the discharge assembly are both housed within the containment vessel 1 1 .
  • An average flow of process gas 85 is passed through the containment vessel 1 1 and exhausted from the exit port 80. As a result, the gas pressure within the containment vessel 1 1 is maintained at a constant value.
  • a cross-flow fan 81 is used to circulate the process gas around the flow loop defined by the flow ducting 82 and the discharge assembly 83, which is generally comprised of the anode and cathode assemblies substantially as described.
  • the gas As a gas volume enters the discharge volume 14, the gas is preionized with ultra-violet radiation generated by the preionization assembly 88, and is subsequently ionized by the application of the main discharge voltage pulse across the anode 52 and cathode 51 electrode assemblies.
  • the electrical discharge that develops within the discharge volume 14 serves as a homogeneous source of energetic electrons.
  • the energetic electrons collide, for example, with diatomic oxygen molecules, a portion of which dissociate to form single oxygen atoms that subsequently recombine with other diatomic oxygen molecules to form ozone.
  • the average ozone concentration of the process gas 85 within the containment vessel 1 1 increases.
  • the temperature of the process gas is desirable to maintain the temperature of the process gas at near room temperature, so that the rate of thermal decomposition of the product gas, such as ozone, is significantly reduced.
  • the product gas may need to be maintained at some other selected temperature. This is accomplished in the present invention by passing the flow of gas 85 that exits the discharge volume 14 through a gas-to-liquid heat exchanger 86.
  • the heat exchanger 86 is designed to remove heat from the process gas resulting from the electrical discharge.
  • the exchanger 86 may be a tube-and-fin type exchanger, or a surface conduction exchanger.
  • the heat energy is transferred to a liquid cooling medium such as water, chilled water, or propylene glycol and water, or other suitable heat transfer fluid within the exchanger 86.
  • a liquid cooling medium such as water, chilled water, or propylene glycol and water, or other suitable heat transfer fluid within the exchanger 86.
  • the fan 81 preferably is a cross-flow fan, so that the fan assembly 81 allows an uniform flow to be developed along the length of the discharge assembly 83.
  • the motor which powers the fan 81 , is easily mounted on the exterior of the containment vessel 1 1 , thereby eliminating the need to protect the motor from the effects of the ozone.
  • a magnetic coupler, or other means of transmission transmits power from the exteriorly mounted motor to the internally disposed cross-flow fan 81.
  • a group of axial fans can be used to circulate the process gas 85; however, the motors which power the axial fans disposed within the containment vessel 1 1 preferably are of the sealed type to protect them from the generated ozone or other produced gas.
  • Hydrogen peroxide is one example of how a well-controlled electrical discharge with average electron energy at high levels can induce chemical changes in a gas by pumping the associating molecules and atoms to excited metastable states. With other chemical processes, the same issues of uniform excitation and processing of the gas for high efficiency and control of the temperature are important, as for ozone.
  • hydrogen peroxide and ozone are used as primary examples of chemical processing of gases by the use of over-voltage, uniform bulk glow discharges.
  • the invention includes bulk glow discharge, and such discharge in conjunction with multiprocess cooling systems to maintain a low gas temperature to avoid causing degradation of the product or stimulating their reaction to go in a direction not desired.
  • a radial glow discharge with an externally sustained discharge provides a means of improving the discharge stability.
  • an alternative embodiment of the inventive apparatus for use in chemical gas processing, provides a pulsed radial self-sustained glow discharge operated at near atmospheric pressure. All other radial discharges have been operated either externally sustained, continuously (non-pulsed), at much lower pressure, or in lasers.
  • the invention includes the operation of a glow discharge in a non-planer radial electrode assembly 160.
  • two concentric, generally cylindrical electrodes 162, 166 define therein the glow discharge volume 164, as shown in Fig. 7.
  • the electrodes 162, 166 are cylinders, but feature curved contours at the corners where the cylinder wall meets the cylinder base, as shown by Fig. 8
  • the glow discharge operates in the discharge volume 164 between the inner electrode 162 (preferably the anode) and the outer electrode 166 (preferably the cathode).
  • the discharge is "radial" because the electron motion is radial from one electrode (e.g., 166) to another (e.g., 162).
  • the process gas mixture is preionized by a preionizer 168 located radially outward from, and behind, the cathode electrode 166 in relation to the discharge volume 164.
  • the preionizer 168 may be disposed in one of three alternative locations. As shown in Fig. 7, the preionizer 168 may be placed radially outward behind the outer electrode 166, thus flooding the inner electrode 162 with UV light upon actuation. This is an attractive location because it allows ample room for the preionizer 168. Preferably, however, the preionizer 168 is located radially inward from the inner electrode 162, thereby flooding the outer electrode 166 with ultraviolet light.
  • Locating the preionizer 168 centrally within the inner electrode 162 is preferred because the relative curvature of the two electrodes 162, 166 provides greater discharge stability when the outer electrode 166 is used as a cathode, and the UV light floods the cathode 166.
  • the preionizer may involve sidelight emission, that is, sources of ultraviolet light, such as sparks between point electrodes, arrayed transversely on either or both sides of the main discharge electrodes 162, 166.
  • FIG. 8 which is a sectional diagram of the discharge volume 164 and electrodes 162, 166 of the radial glow discharge, illustrates this alternative embodiment.
  • the cathode 166 and anode 162 are shown with the discharge volume 164 between them.
  • the preionizers 168, 168' are separate sources of UV light, such as spark electrodes, and are shown located to one, preferably both, sides of the electrodes 162, 166.
  • the point electrodes 168, 168' flood the discharge volume 164 transversely, rather than radially, with ultraviolet light to preionize the discharge.
  • An aspect of the invention for achieving high performance self-sustained discharges is to control the distribution of the photoelectrons while simultaneously controlling the distribution of the electric field. Locating the UV source either radially inward behind the inner electrode 162 or radially outward behind the outer electrode 166 is the preferred embodiment for initiating the self-sustained discharge operation and contributes to higher performance operation with greater reliability.
  • the radial discharge can be preionized by UV flashlamps, for gas mixtures that have a photoelectron process that falls within the transmitted spectrum of the flashlamp envelope.
  • the radial glow discharge embodiment may utilize either of two types of gas flow.
  • Axial gas flow involves gas flow between the electrodes 162, 166 generally parallel to their common axis.
  • the gas may flow radially, either radially outward from the inner electrode 162 through the outer electrode 166 or radially inward from the outer electrode 166 through the inner electrode 162.
  • the gas 137 preferably flows radially out from near the preionizer 1 68, through the inner electrode 162 provided with openings (not shown) to facilitate the gas flow, through the discharge volume 164, and out through the outer electrode 166, which also has openings to facilitate the gas flow.
  • This embodiment offers the capability of operating at high pulse repetition rates. By keeping the gas flow path short, the gas heated by the discharge can be quickly removed in preparation for the next shot.
  • the foregoing radial glow discharge embodiment 160 is particularly advantageous for commercial applications because the geometry provides a means for discharge processing all the gas that is flowing through the apparatus. All of the gas that flows through the radial glow discharge apparatus must pass through the discharge volume 164. Thus, radial glow discharge processing offers advantageous economy and efficiency in commercial applications.
  • the gas processing radial glow discharge embodiment 160 of the invention is distinguishable from a laser discharge because gases typical for an industrial chemical processing applications have very high attachment rates such as the oxygen utilized for ozone and peroxide production, and requires processes distinct from a laser discharge to operate successfully.
  • the first type utilizes an arc between small diameter electrodes 1 68, 168' elevated away from the discharge electrodes 1 62, 1 66, as shown in FIG. 8. This type of preionizer 168 can also be located behind either of the electrodes 1 62, 166.
  • the second type utilizes a dielectric barrier similar to that illustrated in FIG. 4A.
  • a third type is a flashboard UV source, wherein the sparks that create the ultraviolet light are formed between metal pads deposited on the surface of a dielectric material, such as printed circuit board material.
  • the radial discharge can be preionized by preionizers other than UV sources, including x-ray preionizers. These preionizers emit x-rays that penetrate and ionize the process gas or gas mixture. They typically have low conversion efficiency, but are useful in some applications. They have the advantage of being able to penetrate a discharge electrode and thus do not require a thin foil window (as in e-beam preionizer), or a screen window (as in a UV preionizer).
  • the radial discharge can also be preionized by an electron beam. In this embodiment, the e- beam operates at perhaps 1 -2 orders of magnitude in power density less than required to sustain the discharge. Either the x-ray or e-beam preionizers can be located centrally inside the inner electrode 1 62, outside the outer electrode 166, or axially offset from the side of the electrodes (Fig. 8).
  • FIG. 10 illustrates additional aspects of the invention for self-sustained pulsed glow discharge used to produce hydrogen peroxide.
  • the closed cycle hydrogen peroxide generator system 170 operates at elevated pressure.
  • the system is closed, with suitable conduits, piping, and the like for providing recirculation of gases.
  • the system 170 preferably operates at between about 3 and about 10 atmospheres to promote high hydrogen peroxide conversion efficiency. It has been determined that operating the discharge at elevated pressure provides substantially increased yields of hydrogen peroxide.
  • a process gas mixture of water vapor, oxygen, and ozone flows through a conduit into the glow discharge processing container 172.
  • the process gas mixture is processed in the container 172 by the glow discharge, which is powered by the electrical pulsed power supply 178, to produce a product gas stream mixture hydrogen peroxide, water vapor, oxygen and ozone.
  • the glow discharge in the processing container 172 may be generated by linear electrodes; preferably, however, the processing container surrounds a radial discharge electrode assembly such as the electrode assembly 160 depicted in FIG. 7, or alternatively the electrode assembly shown in FIGS. 8 or 9.
  • the product gas mixture is transported via another closed conduit from the processing container 172 to a tank 180 containing liquid water at elevated temperature.
  • the tank 180 for holding water acts as a hydrogen peroxide condenser.
  • the conduit which transports product gas from the container 172 to the tank 172 is provided, upon entry into the container, with any suitable means known for bubbling the product gas into the water.
  • the temperature of the water held in the condenser tank 180 is preferably between about 40°C and about 80 C C, as the water temperature should be cool enough to promote condensation of the hydrogen peroxide constituent of the incoming product gas stream, and warm enough to produce the desired fraction of water vapor in the gas mixture exiting the tank 180 for recirculation as process gas to the discharge container 172.
  • the water in tank 180 is maintained at approximately 75°C.
  • the water in the tank 180 is maintained at the similar elevated pressure as the pressure in discharge processing container 172.
  • the "exit gases" remaining after the extraction of hydrogen peroxide include a mixture of oxygen, ozone, and water vapor gas. Additional oxygen from oxygen source 183 and water from an external water source 182 are injected, by suitable conduit means, into the water tank 180 to compensate for the peroxide condensed out of the product gas stream and extracted from the water bath.
  • the exit gases are vented from the tank 180 and then recirculated, again via any suitable conduit means in the art, to the glow discharge processing container 172.
  • the peroxide and liquid water mixture is continuously removed from the water tank 180 through a pressure regulating valve 186 to maintain the high pressure in the system 170.
  • the concentration, by weight, of the hydrogen peroxide in the water is a function of the amount of water injected relative to water extracted.
  • the peroxide concentration can be controlled from about 1 % up to the safe handling limit of about 70% hydrogen peroxide in water.
  • Other known and suitable means such as mechanical or pressure gas pumps, may be provided as means for transporting the product gas to the tank 180, and for recirculating gases from the tank 180 through the conduit leading back to the discharge processing container 172.
  • the only additional basic equipment, besides that previously discussed, required for commercial production of hydrogen peroxide is a system for packaging the peroxide.
  • There are no carbon-containing fluids in the system so there will be no hydrocarbons to remove.
  • a process gas mixture containing 39% oxygen, 58.5% nitrogen, and 2.5% water vapor was processed by a pair of linear electrodes spaced 5 mm apart and defining a discharge volume of 0.1 liter.
  • the electrodes were specially shaped and contoured, as is commonly known in the art, to eliminate field enhancement and prevent discharge collapse.
  • Fast rise-time high voltage pulses having a peak voltage of approximately 25 kV, a rate of rise in excess of 500 V/nsec, and a pulse width of less than 100 nsec were applied to the electrodes.
  • the product gas was condensed, producing concentrations of 30 mg of hydrogen peroxide per liter of water extracted.
  • the present invention provides an improved self-sustained glow discharge stability in gas mixtures suitable for gas chemical processing through the use of various additives to the process gas mixture.
  • hydrocarbon additives are not appropriate because the presence of high concentrations of oxygen makes the use of hydrocarbon seedants impractical.
  • Certain monatomic and polyatomic additives are stable in the presence of oxygen, and yet provide increased photoelectron yield and reduced glow voltage. These additives are typically, but not necessarily, noble gases, and include nitrogen, helium, argon, neon, krypton, and xenon.
  • Other monatomics and polyatomics are also suitable for photoelectron seedants and ionization rate enhancers. For example, in glow discharge measurements to create hydrogen peroxide from mixtures of water and oxygen, nitrogen proved to be a valuable seedant for enhancing UV photoionization processes and improving discharge stability.
  • the precise control of the voltage in time across the electrodes 1 62, 1 66 is key to successful operation of the self-sustained glow discharge for chemical processing.
  • the radial glow discharge gas processor can utilize magnetic switches, solid-state, or gaseous switches. Magnetic switches, as described herein above, are the preferred embodiment. Magnetic switches are typically custom designed for each application using commercially available materials that may be obtained from Ceramic Magnetics, Inc., for example. In general, the design of magnetic switches is commonly known, and is discussed in detail, for example, in "Magnetic Switches and Circuits" by W. C. Nunnally, Pulsed Power Lecture Series Number 25, Plasma Switching Laboratory, Texas 79409, September 1981 , which is incorporated herein by reference in its entirety.
  • the rate of rise of input voltage to the magnetic switch determines the material and dimensions for the core.
  • the core material and dimensions are selected so that the switch core is saturated (i.e., the relative permeability has been reduced to near 1 ) by leakage current when the input voltage is substantially equal to its peak value. Aligning the peak input voltage with the saturation point of the magnetic switch results in a rapid transfer of energy through the switch because the impedance of the saturated switch is substantially near zero.
  • Solid state switches can also be used for switching the gas mixture such as GTOs and SCRs.
  • the third category includes gaseous switches such as spark gaps, thyratrons, pseudospark switches (for example as disclosed in co-pending Application Serial No. 08/890,485) and other gas switches.
  • Liquid switches, such as water and oil switches are also potential candidates for operating the pulsed self-sustained radial glow discharge for gaseous processing. A key characteristic of all the aforementioned switches is that they must produce a rapid rise time in the electric field to achieve a successful stable operation of the glow discharge for gas chemical processing.
  • FIGS. 2, 6, and 7. It is highly preferable to provide fast rise-time high-voltage pulses to the preionization assemblies 88, 168 and main discharge assemblies 83, 160. Specifically, it is preferable to excite the main discharge with high voltage pulses having rate-of-voltage-rises in excess of
  • Such a pulse is provided to the discharge assembly 83, 160 by a solid state modulator 22 featuring a switched magnetic pulse compression network 21 .
  • the modulator 22 processes direct current (DC) power, provided by the power supply 24, into a continuous train of fast-rise-time high-voltage pulses of relatively short duration.
  • the modulator 22 principally consists of two circuits, for example, a command resonant charge circuit 23, and a multi-stage magnetic pulse compression network 21.
  • a detailed schematic of an example magnetic modulator circuit 22 is shown in FIG. 1 1.
  • the transfer of energy from the filter capacitor 101 to the first capacitor 108 in the magnetic pulse compression network 21 is controlled by a solid state switch, such as an insulating gate bipolar transistor (IGBT) 102 which, when turned on, enables energy to be transferred from the filter capacitor 101 to capacitor 108 in the magnetic pulse compression network.
  • Charging inductor 105 determines the rate at which energy is transferred to first capacitor 108. The precise amount of energy which is transferred to first capacitor 108 is determined by the conduction period of IGBT 102.
  • the voltage to which first capacitor 108 is charged is controlled by a feedback circuit 150B in the modulator timing and triggering circuit 25, which controls the conduction time of the IGBT 102.
  • the feedback circuit 150B uses voltage signals derived from current monitor 106 and voltage divider 107 to determine the conduction time of the IGBT 102.
  • the charging sequence for first capacitor 108 begins with a trigger pulse which turns on the IGBT 102, which in turn causes current to begin to flow from filter capacitor 101 , though the charging inductor 105, and into first capacitor 108.
  • the feedback control circuit terminates the IGBT drive pulse and the IGBT 102 is turned off.
  • the energy stored in charging inductor 105 is transferred to capacitor 108 by f ree- wheeling diode 104.
  • free-wheeling current continues to flow until the energy which is stored in the charging inductor 105 has been transferred to first capacitor 108.
  • silicon controlled rectifier (SCR) 109 is triggered and the energy stored in capacitor 108 is transferred to second capacitor 1 1 1 over a period determined by the values of capacitors 108, 1 1 1 and the saturated inductance of magnetic anode assist 1 10.
  • SCR silicon controlled rectifier
  • an IGBT device may be used in place of SCR 109.
  • the magnetic anode assist 1 10 provides a time delay (several hundreds of ns) for the onset of current flow, so that SCR 109 is in full conduction before it conducts heavily.
  • Saturable inductor 1 17 incorporates a secondary winding which is used to excite the preionization assembly 122.
  • Capacitor 1 19 is placed between the secondary winding 1 18 and the preionization assembly 122 and is used to control the amount of current which is sourced to the preionization assembly 88.
  • the voltage pulse is applied to the preionization assembly before the main high voltage pulse is applied across the anode 124 or 162 and cathode 125 or 166 electrodes.
  • saturable inductor 1 17 saturates and the energy stored in capacitor 1 16 is discharged into the primary of step-up transformer 120.
  • the value of the peaking capacitor 121 is tuned so that the appropriate voltage rise-time and amplitude is developed across the electrodes 124, 162 or 125, 166 so as to maintain a uniform and stable discharge between the electrodes of the discharge cell.
  • the invention is not limited to this circuit. This circuit is for illustration purposes only. Other equivalent magnetic compression pulse circuits can accomplish a similar function.
  • the magnetic modulator network 21 is designed to deliver high voltage pulses to the electrode assembly 83, 160 (Figs. 6 and 7) which have durations of 100-200 ns.
  • the high voltage pulses In order to achieve the desired ozone, hydrogen peroxide, or other product chemical yield, the high voltage pulses must be applied across the electrodes 51 , 52, 162, 166 at a specific repetition rate. To the first order, the average power delivered to the discharge, and therefore the gas chemical production rate, is directly proportional to the repetition rate at which the high voltage pulses are delivered to the discharge.
  • the modulator timing and triggering circuit 25 includes timing and triggering circuitry 150A and the feedback circuit 150B.
  • the timing and triggering circuitry 150A provides a continuous stream of triggering pulses to the IGBT 102 and the SCR 109 within the magnetic modulator network 22.
  • An external analog signal
  • the feedback circuit 150B controls the conduction time of the IGBT 102 by modulating the timing of a reset pulse 149 that is provided to the timing and triggering circuitry 150A.
  • the conduction time of the IGBT 102 may be varied to increase or decrease the amount of energy that is stored in the first capacitor 108 at the beginning of each pulse compression cycle.
  • the feedback circuit 150B monitors the instantaneous energy that will be stored in the first capacitor 108.
  • This instantaneous energy is compared to a desired energy level input that is represented by an analog voltage (Vref) applied to the feedback circuit 1 50B.
  • Vref analog voltage
  • the feedback circuit 150B sends the reset pulse 149 to the timing and triggering circuit 150A, thereby terminating conduction through the IGBT 102.
  • the reset pulse 149 interval increases, which in turn increases the conduction time for IGBT 102 and the energy transferred to the first capacitor
  • the both the frequency and the energy of the high voltage pulses applied to the discharge volume can be controlled by properly varying the analog input signals Vref and Vin to the timing and triggering circuit 25.
  • analog input signals may be provided by manually adjusted external voltage supplies or signal generators, or by automatically adjusted voltages supplied by a microprocessor, a micro-controller, a computer system, or the like.
  • a voltage-to-frequency convertor 140 is used to generate the master timing signal for the modulator system.
  • the repetition rate of the pulse train which is generated by the voltage-to-frequency convertor 140 is controlled by an analog input signal.
  • the pulse train generated by the voltage- to-frequency converter 140 is then used to trigger the first monostable multivibrator 141 , which upon each trigger input generates a pulse 142 of fixed duration, which in turn is used to drive the pulse amplifier 143 used to provide a high current pulse to the gate of SCR 109 in the magnetic pulse compression network 21.
  • pulse 142 is employed as the input trigger to a second monostable multivibrator 144.
  • the multivibrator 144 Upon each trigger pulse the multivibrator 144 generates pulse 145 which is used to determine the delay between the triggering of SCR 109 and the turn on of IGBT 102 in the command charge circuit 23.
  • Pulse 145 is also used to trigger a third monostable multivibrator, turning on the IGBT 102 by generating pulse 147, used to drive the IGBT gate driver circuit 148. Pulse 147 remains high, and therefore the IGBT 102 remains turned on, until monostable multivibrator 146 is reset by the reset pulse 149 derived from the feedback circuit 150B.
  • the feedback circuit 150B calculates the instantaneous energy stored in the charging inductor 105 and capacitor 108, both of which are located in the magnetic modulator network shown in FIG. 1 1 , and compares it to the energy which is to be stored in capacitor 108 for a given pulse. In this manner, the voltage to which capacitor 108 is charged can be precisely controlled.
  • IGBT 102 in the command charge circuit is turned on to charge the first capacitor 108. This causes a current to flow from the DC power supply 24 through IGBT 102 and charging inductor 105 into capacitor 108 in the magnetic pulse compression network 21 . Turning off IGBT 102 causes the energy which is stored in charge inductor 105 to be transferred to capacitor 108 through the free-wheeling diode 104. Regulation of the voltage on capacitor 108 is achieved by turning off IGBT 102 in the command charge circuit 23 at the instant that the sum of the instantaneous energies stored in charging inductor 105 and capacitor 108 yield the desired final charge voltage upon capacitor 108. This is accomplished by calculating the instantaneous energies stored in charging inductor 105 and capacitor 108, summing them, and comparing that sum to the final energy which is desired to be stored in capacitor 108 of the magnetic pulse compression network 21.
  • the instantaneous energy stored in capacitor 108 is calculated by squaring a voltage signal which is proportional to the instantaneous voltage on capacitor 108 with the analog multiplier circuit 153.
  • the instantaneous energy stored in charging inductor 105 is calculated by squaring a voltage which is proportional to the instantaneous current which is flowing through charging inductor 105 with analog multiplier circuit 155.
  • the squared voltage signal which is proportional to the charging current is then multiplied by a fixed gain by amplifier 154 to account for the specific values of charging inductor 105 as well as capacitor 108.
  • the desired final energy to which capacitor 108 is to be charged is calculated by squaring a reference voltage with analog multiplier circuit 156.
  • the squared voltage signal proportional to the voltage on capacitor 108 and the gain adjusted squared voltage signal which is proportional to the charging current are then summed in summing amplifier 152, the output of which is compared to the squared reference voltage.
  • the output of the voltage comparator 151 When the sum of the squared voltage signal and the gain adjusted charging current signal exceeds the square of the reference voltage, the output of the voltage comparator 151 generates a reset signal which is then used to reset monostable multivibrator 146 which causes the IGBT drive pulse to be disabled.
  • IGBT 102 in the command charge circuit is turned off, preventing additional current from flowing from the filter capacitor to capacitor 108 of the magnetic pulse compression network 21.
  • the magnetic modulator network 22 of the invention enhances the total energy that is loaded into a given volume of gas mixture.
  • One of the mechanisms that leads to discharge instability is the creation of super-elastic electrons.
  • Super-elastic electrons are electrons that collide with excited neutrals and, instead of loosing energy to the neutral, they gain energy. These electrons make the discharge much more susceptible to collapse and formation of an arc, and are one of the factors that contributes to the energy loading arc limit.
  • a multi-pulsing process adds energy to promote the chemistry processes without exceeding the discharge stability limits.
  • a given volume of gas is processed with a glow discharge pulse to below the energy loading arc limit.
  • the voltage is removed from the discharge.
  • the process gas constituents relax to a near-Boltzman distribution of the energy among the energy states of the gas.
  • a second pulse is applied to the same gas that allows more energy to be loaded into the same gas mixture. Again, the voltage is removed prior to initiation of discharge runaway and collapse. Subsequent pulses can be applied until the gas is no longer capable of accepting additional energy.
  • the volume of gas is moved out of the discharge volume and a second bulk volume of gas is moved into the discharge and the process repeated.
  • One notable aspect of the invention is the determination that subsequent pulses must be reduced in energy compared to the first pulse, in order for multi- pulsing to be effective. That is, once the gas volume has been processed by a discharge pulse to a particular energy, the next discharge pulse must typically be of less energy to avoid arcing. Even though the second pulse is of reduced energy, the total amount of energy that can be loaded into the gas before it is moved out of the discharge region can be substantially more than could be imposed with a single pulse.
  • the energy of successive pulses can be controlled (i.e., reduced) by varying the energy stored in the first capacitor 108 of the magnetic modulator network 22 (shown in FIG. 1 1 ).
  • the analog reference voltage (Vref) applied to the feedback circuit 150B may steadily reduced to accomplish a controlled droop of the peak voltage on the first capacitor 108 over successive pulses.
  • the DC power supply 24 may be selected so that it operates in a downward sloping portion of its voltage regulation characteristic, thereby reducing the voltage on filter capacitor 101 over successive pulses.
  • a burst mode pulse forming network could be used to provide a burst of pulses with decreasing voltage.
  • burst mode pulse forming network Use of a burst mode pulse forming network with the present invention would require modifications to the magnetic modulator 22 that could be accomplished by one of ordinary skill in the art.
  • a more detailed discussion of burst mode pulse forming networks can be found in a paper entitled "Conceptual Design of Pulse Generators for Driving Recirculating Induction Accelerators," by W. M. Money, M. G. White, and F. W. White, 1991 IEEE Pulsed Power Conference, pages 943-944, which is hereby incorporated by reference in its entirety.
  • the invention is further illustrated by the following non-limiting examples, where useful product gases are produced according to the apparatus and processes of the invention.
  • One industrial application of the present invention is to generate ozone for municipal water applications.
  • the generator is constructed so as to produce approximately 10,000 pounds of ozone per day.
  • the produced ozone is then used to treat water in a municipal water supply.
  • Ozone is exceptionally beneficial for treating water because it leaves no residue as does chlorine.
  • hydrocarbon feedstock such as methane from natural gas is fed into the generator along with a mixture of other additive gas for processing into new chemicals.
  • These gases are then processed by the glow discharge system of the invention where new chemical combinations are initiated by the discharge.
  • the resulting new products are then extracted out of the gas stream and sold as new product.
  • large quantities of hydrogen peroxide may be comparatively economically produced for use in other downstream chemical processes, as an oxidizer, or disinfectant, or the like.
  • Ozone is very useful as a cloth-bleaching agent, particularly to produce the "stone washed look" in blue jeans.
  • a medium-sized ozone generator producing approximately 100 pounds per day, creates ozone in a gas mixture that includes oxygen.
  • the streams of the ozone- bearing gas are directed into the spots of cloth that the manufacturer desires to have bleached.
  • the ozone is consumed by the cloth process bleaching and the resulting gas can then be vented to the atmosphere since it contains mostly oxygen with very little ozone.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Oxygen, Ozone, And Oxides In General (AREA)
  • Lasers (AREA)

Abstract

L'invention concerne un système à haut rendement de traitement au plasma, servant à produire des quantités élevées de gaz, notamment de peroxyde d'oxygène ou d'ozone, pour des applications chimiques, commerciales et industrielles, lequel système est basé sur une décharge électroluminescente homogène. Outre cette décharge homogène, le haut rendement de production d'ozone ou d'une autre produit chimique est obtenu par excitation de la décharge au moyen d'impulsions à haute tension dont la vitesse d'accroissement de la tension est de plus de 500 V/ns et par l'utilisation d'un système interne de circulation de gaz qui maintient la température du gaz de traitement à un niveau où la décomposition thermique de l'ozone, par exemple, est sensiblement réduite. Une décharge luminescente atmosphérique, homogène et stable, est développée par pré-ionisation de la zone de décharge au moyen d'un rayonnement ultraviolet, par exemple, immédiatement avant l'application de la principale impulsion à haute tension aux bornes des électrodes de la cellule de décharge.
PCT/US1999/000911 1998-01-22 1999-01-15 Systeme a haut rendement de traitement de gaz par decharge luminescente pour la production de peroxyde d'oxygene et autres traitements chimiques de gaz WO1999037581A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU22309/99A AU2230999A (en) 1998-01-22 1999-01-15 High efficiency glow discharge gaseous processing system for hydrogen peroxide production and other chemical processing of gases

Applications Claiming Priority (4)

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US7221198P 1998-01-22 1998-01-22
US60/072,211 1998-01-22
US5737798A 1998-04-08 1998-04-08
US09/057,377 1998-04-08

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Cited By (16)

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EP1052220A2 (fr) * 1999-05-13 2000-11-15 21 Century Environment Co. Ltd. Dispositif de génération d'un gaz ionisé par décharge haute tension
WO2007040415A1 (fr) * 2005-10-05 2007-04-12 Instytut Wysokich Cisnien Polskiej Akademii Nauk Procede permettant de mener des reactions chimiques et reacteur chimique
WO2008025917A2 (fr) * 2006-08-31 2008-03-06 Arkema France Procede de fabrication du peroxyde d'hydrogene
CN100460315C (zh) * 2003-11-28 2009-02-11 大连理工大学 室温下直接合成过氧化氢的装置和方法
WO2010150096A1 (fr) * 2009-06-25 2010-12-29 Toyota Jidosha Kabushiki Kaisha Générateur d'ozone
ITVR20120123A1 (it) * 2012-06-13 2013-12-14 Renato Consolati Dispositivo per la sollecitazione energetica di una sostanza.
CN104619106A (zh) * 2015-01-15 2015-05-13 合肥工业大学 一种实现大气压下空气中均匀辉光放电的装置
KR101709644B1 (ko) * 2015-12-21 2017-02-23 에스케이건설 주식회사 과산화수소를 생성하는 수처리 장치
US20200343074A1 (en) * 2019-04-05 2020-10-29 Servomex Group Limited Glow plasma stabilization
CN111992161A (zh) * 2020-09-04 2020-11-27 江西科技学院 用于铜矿渣污染物的光催化降解装置及其使用方法
CN112320765A (zh) * 2020-09-29 2021-02-05 欧奏沛尔(江苏)环保技术有限公司 复合高压电极及双电极冷却臭氧发生器
US11459883B2 (en) 2020-08-28 2022-10-04 Halliburton Energy Services, Inc. Plasma chemistry derived formation rock evaluation for pulse power drilling
US11499421B2 (en) 2020-08-28 2022-11-15 Halliburton Energy Services, Inc. Plasma chemistry based analysis and operations for pulse power drilling
US11536136B2 (en) 2020-08-28 2022-12-27 Halliburton Energy Services, Inc. Plasma chemistry based analysis and operations for pulse power drilling
US11585743B2 (en) 2020-08-28 2023-02-21 Halliburton Energy Services, Inc. Determining formation porosity and permeability
US11619129B2 (en) 2020-08-28 2023-04-04 Halliburton Energy Services, Inc. Estimating formation isotopic concentration with pulsed power drilling

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Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1052220A3 (fr) * 1999-05-13 2003-02-05 21 Century Environment Co. Ltd. Dispositif de génération d'un gaz ionisé par décharge haute tension
EP1052220A2 (fr) * 1999-05-13 2000-11-15 21 Century Environment Co. Ltd. Dispositif de génération d'un gaz ionisé par décharge haute tension
CN100460315C (zh) * 2003-11-28 2009-02-11 大连理工大学 室温下直接合成过氧化氢的装置和方法
WO2007040415A1 (fr) * 2005-10-05 2007-04-12 Instytut Wysokich Cisnien Polskiej Akademii Nauk Procede permettant de mener des reactions chimiques et reacteur chimique
WO2008025917A2 (fr) * 2006-08-31 2008-03-06 Arkema France Procede de fabrication du peroxyde d'hydrogene
FR2905370A1 (fr) * 2006-08-31 2008-03-07 Arkema France Procede de fabrication du peroxyde d'hydrogene
WO2008025917A3 (fr) * 2006-08-31 2008-04-17 Arkema France Procede de fabrication du peroxyde d'hydrogene
WO2010150096A1 (fr) * 2009-06-25 2010-12-29 Toyota Jidosha Kabushiki Kaisha Générateur d'ozone
ITVR20120123A1 (it) * 2012-06-13 2013-12-14 Renato Consolati Dispositivo per la sollecitazione energetica di una sostanza.
CN104619106B (zh) * 2015-01-15 2018-04-20 合肥工业大学 一种实现大气压下空气中均匀辉光放电的装置
CN104619106A (zh) * 2015-01-15 2015-05-13 合肥工业大学 一种实现大气压下空气中均匀辉光放电的装置
KR101709644B1 (ko) * 2015-12-21 2017-02-23 에스케이건설 주식회사 과산화수소를 생성하는 수처리 장치
US20200343074A1 (en) * 2019-04-05 2020-10-29 Servomex Group Limited Glow plasma stabilization
EP3719482A3 (fr) * 2019-04-05 2020-12-09 Servomex Group Limited Stabilisation de plasma luminescent
US11459883B2 (en) 2020-08-28 2022-10-04 Halliburton Energy Services, Inc. Plasma chemistry derived formation rock evaluation for pulse power drilling
US11499421B2 (en) 2020-08-28 2022-11-15 Halliburton Energy Services, Inc. Plasma chemistry based analysis and operations for pulse power drilling
US11536136B2 (en) 2020-08-28 2022-12-27 Halliburton Energy Services, Inc. Plasma chemistry based analysis and operations for pulse power drilling
US11585743B2 (en) 2020-08-28 2023-02-21 Halliburton Energy Services, Inc. Determining formation porosity and permeability
US11619129B2 (en) 2020-08-28 2023-04-04 Halliburton Energy Services, Inc. Estimating formation isotopic concentration with pulsed power drilling
CN111992161A (zh) * 2020-09-04 2020-11-27 江西科技学院 用于铜矿渣污染物的光催化降解装置及其使用方法
CN112320765A (zh) * 2020-09-29 2021-02-05 欧奏沛尔(江苏)环保技术有限公司 复合高压电极及双电极冷却臭氧发生器

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