JP2010510871A - Apparatus and method for destroying organic compounds in large volumes of exhaust in commercial and industrial applications - Google Patents

Abstract

Nonthermal plasma (NTP) and integrated catalyst system (ICS) are used for neutralization of volatile organic compounds (VOC) and / or halogenated volatile organic compounds (HVOC). Some of these compounds are effluents with odorous and / or fine organic particles (smoke) released into the environment by commercial and / or industrial air flow. This system utilizes a dielectric barrier discharge (DBD) electrode and dielectric design to generate an NTP field, combined with catalytic function, sufficient reactive oxygen species (ROS), hydroxyl species and other highly ionized molecules and Oxidizes VOC and / or HVOC and / or fine organic particulate contaminants in the air stream to generate atomic species and thereby to be broken down into simpler non-pollutant, odorless compounds that can subsequently be released into the environment And / or reduction. The system draws contaminated or uncontaminated atmospheric pressure air and / or gas through an NTP field generated by the DBD device and combines this air with the air and / or gas to be treated. Works by. The DBD device is designed with catalyst material integrated into the DBD cell, and any additional catalyst immediately after the cell, to allow the passage of large air flows inherent in commercial or industrial processing. Designed.
[Selection] Figure 1

Description

  Field: The present invention relates to the field of near atmospheric or atmospheric pressure air and / or gas derived from commercial and industrial operations, where the air and / or gas used in such activities is a contaminant. It is said that. Some of them may or may not be odorous, and removal of the released odors has been a challenge. These pollutants need to be removed and / or converted into non-problematic compounds before they are released into the surrounding atmosphere. This is the field of treatment when volatile organic compounds (VOC) and / or halogen volatile organic compounds (HVOC) and / or hydrocarbon compounds (HC) and / or fine suspended organic particulate matter such as smoke are included. . The field of processing where these contaminant removal systems include non-thermal plasma (NTP) fields with integrated catalyst components and / or NTP fields and / or multiple NTP fields with integrated catalyst components .

Prior art: Airborne volatile organic compounds and / or halogen volatile organic compound contaminants (VOC and HVOC) and / or hydrocarbon compounds and / or fine suspended organic particulates (smoke) have odor Some are odorless. Collectively referred to as airborne pollutants here, they are released from various sources and treatments into the surrounding air and can fill the residential area and surrounding air over several kilometers from the source even in mild weather conditions There is sex. A number of such airborne pollutants are considered pollutants and emission levels are regulated by the US Environmental Protection Agency (EPA). However, if the substance is not regulated but has odor, the odor perception may vary from a somewhat unpleasant level to an unbearable level for residents in the affected area. . This is a common problem in areas close to such sources. Examples of airborne pollution emissions that are considered odor sources include industries that process organic materials such as municipal waste processing, urban composting, bread industry, chocolate processing, fried foods and other related humans. Food processing. Also included are industries that produce animal feed for the production of various types of food consumed by humans, for pets, fish, poultry and pig farming, and for general agriculture. Industries that process other organic materials and release odorous airborne pollutants include those that process livestock products, including meat processing, fertilizers and animal fat refineries. Other sources of odorous airborne pollutants include small-scale composting facilities, sewage treatment centers, garbage dumps, and other industrial organic treatment facilities. In general, in these commercial and industrial activities, gases are emitted from preparation, handling, storage, cooking, grinding, drying, cooling, manufacturing, reduction and other related processes. These exhausts together contain medium to low concentrations of VOCs and HVOCs, and these VOCs and HVOCs contain amines, aldehydes, and fatty acids. These amines, aldehydes, and fatty acids can be completely evaporated and / or formed into aerosols inherent to the material being processed or produced from processing, and their preparation and / or handling activities Either to the exhaust gas stream. Typically, these industries emit large amounts of gas, which can be from 100 to 500,000 cubic feet (ACFM) or more per minute.

Agricultural activities for raising animals for food production, such as pig farms, poultry farms, and dairy farms, also emit strong odors from the compost and barn ventilating odors into the surrounding air. Under certain conditions, it may emit an amount of malodor that fills several square kilometers.

In addition, solvents, cleaning fluids, paint fumes, printed circuit board manufacturing and other VOCs and HVOCs are also sources of environmental air emissions from other general industrial and commercial activities. Some VOCs have little or no odor but are considered air pollutants and / or carcinogens and must be reduced to harmless compounds by treatment before being released into the environment. is there. If the odor of the target air pollutant is extremely strong, even if the concentration is in the range of 1 billion percent, it may become a foul odor or exceed the environmental emission standards. Is done.

To oxidize and / or reduce VOCs and other air pollutants resulting from commercial and / or industrial treatment activities that should be released to the environment so that the emissions of the emitted exhaust gas are within environmental regulatory standards. There are a variety of systems designed. Some of these systems utilize non-thermal plasma (NTP) formed in dielectric barrier discharge (DBD) cells to make active or reactive oxygen species (ROS), hydroxyl compounds at various ionization levels. And a wide range of active species, such as molecules and atoms, are then mixed with the gas to be treated to oxidize and / or reduce VOCs and HVOCs by chemical reactions caused by the active species generated by the NTP field. Of the VOCs and HVOCs released from commercial and industrial processes, some are compounds that humans normally perceive as odors, but many are ultimately reduced to carbon dioxide and water vapor. However, depending on the chemical nature of the contaminant, other products may be generated by high energy ions and active species generated by the non-thermal plasma field created by the DBD cell.

The active species described herein is a chemical compound that provides sufficient electrical energy using a dielectric barrier discharge or the like to set the ground state to the standard state (or at atmospheric pressure and 20 ° C.) of these molecules (or At useful concentrations by changing the molecule of interest from the ground state to the desired excited active state and splitting several molecules into their atomic components (as atmospheric and temperature conditions that can occur in NTP field state locations) The atomic species to be created. The active species is usually indicated by “·” in the literature, and is expressed as O · or the like if it is active oxygen (in this case, atomic oxygen). Activation occurs through a number of mechanisms including direct electron or secondary collisions, light absorption, molecular processes associated with ionization, or internal excitation.

Dielectric barrier discharge (DBD) technology has been used to generate NTPs that generate the active species necessary for the purposes of the present invention. Since such techniques qualitatively limit the eV imparted to the gas through the barrier, this case is mainly concerned with reactivity involving various hydroxy radicals and excited oxygen atoms. Although it is an oxygen species (ROS), other electron activities also assist in this process. For active species generated in the NTP field, ROS species with the highest reduction potential (about 2.4-6.5 eV) have utility in half-concentrations less than about 200 microseconds, as is the case with singlet oxygen. Is the shortest. These react with all the compounds that permeate the NTP field, but if the VOC and / or HVOC to be destroyed is highly ionic, their ROS species are highly reduced to reduce and / or oxidize. A reduction potential oxidant is required, which has the shortest lifetime and is only found in sufficient concentrations in the NTP field. The reaction of these high reduction potential radicals, these particles, and the VOC and / or HVOC molecules that react with them causes these radicals to rapidly decay outside the NTP field to become less active species. Occurs only in the NTP field. These radicals react with odorous molecules by oxidative and reductive transformations, converting VOC molecules into simpler molecular compounds that are no longer perceived as odors and are removed from the category of pollutants. Other activities that occur within NTP are electron impact activity, bombardment, and impurity light emission that affect all molecules in the field, including the compound of interest. The action of this electron also breaks the VOC and / or HVOC compound molecular bonds, as well as the generation of the desired ROS, which promotes the odor and / or the oxidation and / or reduction ROS activity of the VOC compound. . The NTP field also produces various radicals with a lower reduction potential (between about 1.4 and 2.4 eV) in the ROS, which have a half-life of about 100 milliseconds at normal temperature and pressure. Long life with a few minutes. These radicals react with VOC and HVOC compounds that respond to this level of reduction potential and oxidation for degradation. These reactions occur in both the NTP field and the airflow outside the NTP field because the radicals are active for longer periods of time, usually 0.1 to 10.0 seconds or more, and air The stream is carried out of the NTP field via the DBD. These longer-lived radicals also affect their changes to VOC and HVOC compounds due to oxidative and reductive transformations, and the compounds of interest are simpler molecules that are not considered perceptible as pollutants or odors. Is converted to the form of Also, by such transformation, complex organic and hydrocarbon molecules eventually become the simplest oxides such as carbon dioxide, hydrogen peroxide (water-H ₂ O), nitrogen (N ₂ ) and the original Changes to other simplified oxide forms of the elements present in the complex. When a large air flow needs to be processed, usually a portion of the air to be processed is passed through the NTP field and processed to activate excess ROS, hydroxyl, ionized molecules and atoms, These generated species are then mixed with the rest of the air to be treated immediately, completing the treatment of the entire air stream.

The four oxidation states of molecular oxygen are known. That is, [O ₂ ] ⁿ , where n = 0, +1, −1, and −2, and represents diatomic oxygen, diatomic oxygen cation, superoxide anion, and peroxydianion, respectively (formula in ^{_{3 O 2, 3 O 2 +}} , 3 O 2 -, and is represented by ³ O ₂ ^-2). Also, ³ O _2, which is “ordinary” oxygen in the air, is in a “base” (not energetically excited) state. This is a free “diradical” with two unpaired electrons. The two outermost electron pairs of oxygen have parallel spins indicating a “triplet” state (the overwriting “3” on the head is usually omitted for simplicity). Oxygen itself is a common terminal electron acceptor in biochemical processes. This is not particularly reactive and itself does not cause significant oxidative damage to biological systems. However, it is a precursor of other potentially toxic oxygen species such as superoxide anion radical, hydroxy radical, peroxy radical, alkoxy radical, and hydrogen peroxide. Other highly reactive molecules include singlet oxygen ( ¹ O) and ozone (O ₃ ).

Ordinary oxygen does not react well with most molecules, but is “activated” by being given energy (naturally or artificially obtained energy, electrical energy, thermal energy, photochemical energy or nuclear energy). , Converted to reactive oxygen species (ROS). Changing to a highly reactive state by adding one electron to oxygen is called reduction (Formula 1). The donor molecule that has given the electrons is oxidized. Triplet oxygen becomes superoxide, that is, O _2. As a result of this monovalent reduction. This is both a radical (., Point symbol) and an anion (charge: -1). Other reactive oxygen species known to be produced by NTP include the following. (On the Ionization of Air for Removal of Noxious Effluvia [Air Ionization of Indoor Environments for Control of Volatile and Particulate Contaminants with Nonthermal Plasmas Generated by Dielectric-Barrier Discharge] Dr. Stacy L. Daniels, IEEE Transactions on Plasma Science, Vol. 30 , No. 4, August 2002):
O ₂ + e → 0 ₂ · ⁻ (Formula 1)
2O ₂ · ⁻ + 2H + → H ₂ O ₂ + O ₂ · (Formula 2)
O ₂ · ⁻ + H ₂ O ₂ → O ₂ + OH · + OH ⁻ (Formula 3)
O ₂ · ⁻ + 2H ₂ O → O ₂ + H ₂ O ₂ · ⁻ + OH · ⁻ (Formula 4)
^{_{2 O 2 · - + O 2}} + H 2 O → 2 O 2 + OH - + OH · ( Equation 5)

Several reaction schemes for interconversion of other reactive oxygen species (ROS) to other species have been identified or assumed. In any case, the reactive oxygen species described above are more likely to be generated within the NTP and react with odorous molecules to make them not considered pollutants or perceived as odorous. Some may convert it into a simple molecule.

Typically, the amount of air and / or gas to be treated commercially and industrially has contaminants such as cooling water or other vapors and liquids, certain particles, or a mixture of cooling liquid and particles. The problems arising from the use of dielectric barrier discharge (DBD) cells that generate NTP for the treatment of industrial-scale pollutant gas streams are associated with these gases, even when used for a period of time, sometimes even for a few minutes Contaminants that are accumulated in the cell may cause an electrical short from the hot electrode in the cell to the insulator and support frame, ground frame or ground electrode. This interferes with the designed electrical characteristics of the DBD cell. In the event of a continuous arc or a defect in the DBD insulator, any NTP generation capability of the DBD cell is immediately destroyed. In some cases, a rapid flashover arc occurs and disappears. An industrial example of this is the transmission of commercial power, with porcelain insulators on high-voltage lines, or more modern types of insulators made of polymer concrete, with short duration Flash durable. Since the electric arc has a very high temperature and the parts in contact with the arc are usually damaged, if a sustained arc occurs, it is very likely that the DBD cell component has failed, To restore the electrical dielectric integrity of the DBD cell, the DBD cell needs to be cleaned and the damaged parts must be replaced. It is an important and practical consideration to pay due attention to the design of the DBD cell so that the impact of normal operation in an industrial environment on the operation of the DBD cell is minimized.

  According to the present invention, a dielectric barrier discharge (DBD) cell composed of a catalytically active material is used to generate a non-thermal plasma (NTP) field. This cell is particularly useful as part of an apparatus for treating gases containing volatile organic compounds (VOC) and / or halogenated volatile organic compounds (HVOC), some of which are particularly odorous. Some are not. This cell has a limited area where NTP is generated, and the NTP is arranged in the cell so that the frame is not damaged by the NTP and the terminal is not short-circuited so that the NTP is separated from the support frame and the electrode terminal. Electrodes. Furthermore, at least all electrode portions in the cell where the contaminated gas is treated pass through the support frame in a sealed manner. Thus, contaminants in the air stream excited by the NTP field do not interfere with the electrical connection to the electrodes. Furthermore, the gas processing apparatus of the present invention generates an active species by passing a part of air and / or the atmosphere to be processed through NTP for a gas that can be sufficiently processed with active species having relatively low energy, The activated air is then mixed with the gas to be treated so that the longer lasting active species react with the VOC and HVOC molecules in the air and / or gas and all the air and / or gas to be treated May be configured to process. In more difficult gases to process, some or all of the gas to be processed passes through the NTP, where many forms of electronic activity in the NTP field and all of the shorter-lived, higher-energy electron volt active species are Acts on the compound to be treated. A catalytically active material may be present in the DBD in that the electrode may consist of a catalytically active material or may be coated with a catalytically active material, and The dielectric separating the electrodes may be coated with a catalytically active material, and further, to facilitate the desired redox reaction to destroy the compound of interest, the DBD outlet and Other catalytically active materials may be present immediately in the mixing chamber region. In general, when all of the gas to be treated is passed through the cell, a cell with a greater ability to generate NTP is required.

According to the present invention, a processing device for volatile organic compounds (VOC) and / or halogenated volatile organic compounds (HVOC), some of which may or may not be odorous, and A processing apparatus that is organic particulate particulate contaminants in air and / or gas exhaust and includes all of the following: a planar dielectric barrier discharge (DBD) having a gas flow path therethrough Non-thermal plasma (NTP) generating cell assembly, wherein the cell has a plurality of electrical hot and ground electrodes that are alternately positioned opposite to each other, the air flowing through the gas flow path and / or Alternatively, all the electrodes are made of catalytically active material so that gas flows through the air space between these electrodes so that they flow through the air and / or gas flow path. Luke, or it is either being coated with the active material as a catalyst. The dielectric material is separated from the electrode having an AC voltage potential difference during operation, and the electrodes are separated to prevent direct arcing. When sufficient electric power is applied, the AC voltage potential difference is activated and the DBD becomes NTP field. To generate various reactive species in various states of low, medium and high ionization, namely reactive oxygen species (ROS), hydroxyl species, molecular species and atomic species. A dielectric barrier discharge (DBD) type specific thermal plasma generating cell assembly, wherein the dielectric barrier may be coated with a catalytically active material; a gas inlet of the cell through the cell to the gas flow path; and A gas outlet of the cell for discharging the gas that passes through the cell and further passes through (possibly) a mesh that is active as a catalyst for the DBD outlet where the gas needs to pass.

  According to the invention, a VOC and / or HVOC treatment device as described in the preceding paragraph, which may be odorous in the gas exhaust and / or may contain organic fine particulate contaminants, The gas inlet of the DBD assembly is connected to a source of air and / or gas exhaust, and the gas outlet of the DBD assembly is exhausted after being treated with the reactive species generated by the NTP. For this purpose, a processing device for discharging the processed air and / or gas.

  According to the present invention, the VOC and / or HVOC treatment device described in the preceding paragraph may be odorous and / or may contain organic fine particulate contaminants. The air and / or the remainder of the gas to be treated is split from the whole of the air and / or the gas to be treated, passed through the DBD cell and activated by the NTP field And / or further comprising a gas mixing chamber so that it can be mixed with a portion of the gas to be processed, so that a portion of the air and / or gas is processed and within the mixing chamber immediately after the DBD cell Part of the air and / or gas since it contains extra reactive species to be mixed with part of the gas that has not passed through the DBD cell The mixed chamber gas outlet discharges all the mixed and processed air and / or gas that can be treated by the excess of the reactive species produced and discharged through a conduit and through the conduit; Processing equipment.

  According to the present invention, the VOC and / or HVOC treatment device described in the preceding paragraph may be odorous and / or contain organic fine particulate contaminants. Wherein the DBD cell assembly, each cell comprising a plurality of alternating potential electrodes, comprises a catalyst carrier conductor or is separated by a dielectric material that may or may not be coated with the catalyst material. A processing device that is either coated with a non-conductive frame and is held in place and a large number of cells are arranged in parallel for the treatment of a large air flow.

  According to the present invention, the VOC and / or HVOC treatment device described in the preceding paragraph may be odorous and / or contain organic fine particulate contaminants. If excess ozone is present in the exhaust and / or gas to be treated, the exhaust for the production of more gaseous catalytic reduction reactions and possibly for the destruction of excess ozone And / or a treatment device in which the gas may be sent to one additional catalyst carrier or two catalyst carrier systems.

According to the present invention, the VOC and / or HVOC treatment device described in the preceding paragraph may be odorous and / or may contain organic fine particulate contaminants. The assembly holding the electrodes and the dielectric forming the DBD assembly is made of alumina or borosilicate glass as part of the dielectric material, and part of the ceramic material is particularly high A processing apparatus that is polymer concrete designed for voltage insulator applications, wherein a portion of the insulating material is Teflon or other non-metallic insulating material.

  According to the present invention, the VOC and / or HVOC treatment device described in the preceding paragraph may be odorous and / or contain organic fine particulate contaminants. Wherein the electrode of the DBD is either composed of a material that is active as a catalyst or is coated with a coating that is active as a catalyst, and is spaced in the middle of the surface of the electrode Arranged on the plane of alternating hot and ground electrodes separated by dielectric barriers, between the electrodes and the dielectric barrier, between each electrode and the isolation dielectric There is a gap in the range of 25.0 mm, which can be 0.5 mm to 10.0 mm thick, and the hot electrode, the dielectric barrier, the ground electrode, and the dielectric barrier are spaced apart at equal intervals. To have. Therefore, both the hot electrode and the ground electrode are exposed to the air to be treated, and the catalysis of the electrode and, if possible, the dielectric barrier, can have a maximum effect, the electrode A processing apparatus that is in a positional relationship of parallel plate arrangements for creation, so that when electrically excited as necessary, an NTP field is generated between the surfaces of opposing electrodes.

  According to the present invention, the VOC and / or HVOC treatment device described in the preceding paragraph may be odorous and / or may contain organic fine particulate contaminants. Wherein the electrically insulating material carrying the electrode in place is a ceramic material, and the dielectric separating the electrode is also at a location where the electrode is held aligned with the cell assembly. Extending beyond the electrodes to all sides of the plane, so that the distance covered by the electric arc is maximized, and voids are used to complement the insulating properties of the insulating material, and the ends of the electrodes The parts are cut off in an offset shape so that their ends are opposite where they are held in place in the electrode end insulator near the DBD support frame. Therefore, the formation of the NTP field in the vicinity of the end of the electrode whose ends are gripped in place by the rectangular support frame is prevented, so that the NTP field is not in contact with the support frame. A process for maximizing the travel distance of the electric arc between the hot electrode and the ground electrode around the ceramic dielectric barrier separating the surfaces of the opposing electrodes and preventing a short circuit of the electric DBD capacitor assembly circuit; apparatus.

  According to the present invention, the VOC and / or HVOC treatment device described in the preceding paragraph may be odorous and / or may contain organic fine particulate contaminants. When an electric power is applied to the electrodes, an NTP field is generated between the electrodes, and the outer periphery of the hot electrode is substantially equal to the outer periphery of the hot electrode. In which the NTP field is separated from the frame and from the individual electrode support insulators.

  According to the present invention, the VOC and / or HVOC treatment device described in the preceding paragraph may be odorous and / or may contain organic fine particulate contaminants. Then, electric power is applied to the electrodes to generate a “glow discharge” between the electrodes, not an NTP field of “filament discharge”. The power is an AC voltage of about 1000 volts to about 150,000 volts at a frequency of about 30 Hz to about 50 MHz, and alternatively, the applied power may be a bipolar pulse, and its pulse rise time is 10 nanoseconds to 500 microseconds, the pulse duration may be equal to the rise time, or may be as long as 500 microseconds, and the corresponding fall time is the same as the rise time, and then the same as above Rise time is followed by reverse polarity pulses with the same or similar voltage power characteristics, and the off period is such that the repetition rate corresponds to a range of joules per second per square centimeter of 0.01 to 1,000 Alternately, the system produces a visible “glow discharge” NTP field between the electrodes. Therefore, the positive pulse and the combination of the negative going pulses, may be supplied to the direct current bias processor.

  According to the present invention, the VOC and / or HVOC treatment device described in the preceding paragraph may be odorous and / or contain organic fine particulate contaminants. And additionally comprising a dielectric barrier discharge NTP generation cell power control system, and a sensor of ozone in the processed processed gas emanating from the apparatus, wherein the ozone sensor is the processed Display the ozone content of the gas, the ozone content of the processed gas indicates the degree of processing of the gas, and the display of the ozone content of the processed gas is the control scheme To the control system for controlling the power supplied to the cell with a proportional-integral-derivative (PID) type controller for the first part of the Using a restriction on the mouth concentration and the power that can be applied to the DBD, a secondary control scheme is programmed to reduce the ozone below a set value and the plasma power is the design maximum, The air flow through the DBD can be reduced, so that sufficient active species are generated in the air and / or gas to indicate that the target contaminant is completely destroyed, The residual ozone of the air and / or gas passing through the DBD and NTP fields is always controlled, and the control scheme may not require the air to pass through the NTP field and be processed and reduced. Can contain only the first part (plasma field power modulation) that is reliable, or all in any application In situations where it may be necessary to change the air flow through the NTP field to guarantee residual ozone in the obtained case, plasma power modulation in the first part of the control scheme and then the control scheme The processing apparatus may be a split control scheme that includes both air flow modulation in the second part of the.

  According to the present invention, the VOC and / or HVOC treatment device described in the preceding paragraph may be odorous and / or contain organic fine particulate contaminants. A processing apparatus comprising the following in all claims: one or more dielectric barrier discharge (DBD) non-thermal plasma (NTP) generating cells connected in series and / or in parallel and / or in series-parallel A gas flow path therein, the cell having a plurality of electrically hot electrodes and a ground electrode, both electrodes being electrically conductive and made of a catalytically active material, Alternatively, it is coated with a catalytically active material, and each alternating hot and ground electrode is separated by a dielectric barrier, so that when electrically excited, it produces a non-thermal plasma, which The gas flowing in the gas flow path is flowed through the air space between these electrodes to form the NTP field located in the gas flow path, forming between the dielectric barrier and the electrode plate A dielectric barrier discharge (DBD) non-thermal plasma (NTP) generating cell passed through the NTP field; a gas inlet leading to the gas flow path through the DBD cell; and a gas passing through the DBD cell A DBD cell gas outlet for exhausting; a gas mixing chamber having a first section and a second section gas inlet for a gas inlet connected to the DBD cell gas outlet, the mixing chamber comprising first and second A gas mixing chamber that mixes gas entering the chamber from two inlets; and exhausts gas that has passed through the mixing chamber A mixing chamber gas outlet for the cell gas inlet to be contaminated gas source, atmospheric source, or both contaminated gas and atmospheric source to be treated To facilitate the redox reaction of the mixing chamber and then to increase the likelihood of an ozone destruction catalyst further downstream of the air and / or gas stream A mixing chamber gas outlet, which may have additional catalytic material.

  DBD cells that generate NTP fields are planar in design and can utilize active conductive electrodes or other conductors as catalysts that may or may not have active coatings as catalysts. . Further, the thickness of the electrode is in the range of 1 to 10 mm, the height is in the range of 5 mm to 1500 mm or more, the length is in the range of 10 mm to 2500 mm or more, and the surface is 0 in distance. Aligned so as to be evenly spaced by a gap in the range of 1 mm to 50.0 mm. A dielectric barrier may be required if the power source is an alternating current with a frequency lower than 5 MHz and / or the voltage rise time is slow, and if necessary, the dielectric barrier is centered on the gap between the electrodes, The thickness of the dielectric barrier is in the range of 0.5 mm to 10.0 mm so that a gap always remains between both surfaces and the surface of the electrode, and the size is based on the space between the electrodes. In order to prevent an arc air path from electrode to electrode around the dielectric barrier, the length and width dimensions of the dielectric barrier extend beyond the end of the electrode for a sufficient distance. The dielectric barrier may or may not be coated on one or both sides with a catalytically active coating or a material that increases the dielectric properties of the dielectric. If the frequency of the power supply is higher than 5 MHz, or a fast rising pulse with a short power supply duration, the rise time is in nanoseconds and the duration is in nanoseconds, a dielectric barrier may not be necessary, There are only gaps between the electrodes.

1. There are two types of electrodes within a DBD: a “hot” electrode and a “ground” electrode. These are flat parallel mounted plates of conductive material and may be of catalytically active material or coated with such material. Also, the NTP field is exposed where the catalyst material promotes the desired chemical reaction in the gas phase. Where the electrode ends are close to and supported by the electrode support frame, that portion of each electrode has chemical resistance and high thermal resistance characteristics. For example, it is sealed in a high pressure insulator of a ceramic material such as borosilicate glass, alumina ceramic or polymer concrete. The insulators at the ends of the electrodes are sealed to the ends of each electrode to ensure electrical insulation of the electrodes in the electrical insulating material (end insulator), so that there is no gap between the electrodes and the electrode support frame Are electrically insulated. The metal portion of each electrode has a tab that extends through one end insulator and through the support frame for electrical connection to each electrode. The occurrence of the NTP field near the support frame is due to a series of cutout regions of the electrodes in the end insulator, facing the “ground” electrode conductive component in the insulated end connector, among the “hot” electrode conductive components It is prevented by not having. When appropriate power is applied to the electrodes, the NTP is formed in the space between the two electrodes where the “hot” electrode faces and faces the “ground” electrode and may be separated by a dielectric barrier. . The “hot” and “ground” electrodes are alternately arranged and face each other so that there is a “ground” electrode on either side of the “hot” electrode and a “ground” electrode on either side of the “ground” electrode. There are alternating “hot” electrodes, with the “outer” electrodes of each frame being ground electrodes. Thus, when energized, all electrodes generate NTP fields on both sides, except for the outer ground electrode, which faces the inner surface of the DBD assembly and generates an NTP field only on the side with the opposing “hot” electrode. effective. The range of the number of electrodes is one “hot” electrode, one ground electrode on one side, and NTPs formed on both sides of the “hot” electrode. That is, from the example of forming two plasma regions, there are 40 “hot” electrodes or more and 40 “hot” electrodes with one “ground” electrode on each side of each “hot” electrode. In addition, 41 “ground” electrodes are included in one row in which “hot” electrodes and ground electrodes are alternately arranged, and an NTP field is generated on all sides of each “hot” electrode when energized.

2. Since the atmospheric pressure glow NTP has the largest number of chemically active species to be generated, the nature of the NTP field is preferably an atmospheric pressure glow type field rather than a filamentous glow plasma. The design of the DBD to generate the desired type of NTP field includes the spacing between the electrode plates, the choice of dielectric barrier material, its size and thickness, the electrode plate thickness, the electrode support frame material, the catalyst material used , And how it is incorporated into the DBD assembly, and defined by a number of practical considerations, such as the electrical network and power characteristics applied to the DBD. If the spacing between the electrodes is too wide and / or if the voltage applied to the electrodes is insufficient and / or if the electrical impedance is not matched between the electrode capacitance and the inductance of the power supply and / or the voltage If the rise time is too slow and / or if the electrode power density is insufficient, a streamer discharge NTP is formed instead of an atmospheric pressure glow discharge NTP field. If the power delivered to the DBD is unsuitable for the DBD material used, for example if the dielectric barrier itself or frequency is too low and / or the impedance is not matched, Electrical losses occur, overheating occurs in the DBD itself, causing the component to fail quickly, resulting in waste and a significant percentage of the total power required. The efficiency of reactive species generation is orders of magnitude lower when streamer discharge NTP fields are formed, and the efficiency is affected by operation at lower frequencies, so that the characteristics of glow discharge are maintained so that the characteristics of glow discharge are maintained. It is important that the electrode spacing, the use of the power supply are designed and that all electrical parameters are adjusted. In addition, this system is intended for commercial and industrial use and often has to be operated 24 hours a day, 7 days a week, both in terms of mechanical and electrical integrity in a vibrating industrial environment. Due to the robust structure and less than ideal air conditions and other factors, structural materials and methods that are not fragile are needed for all aspects of the design, especially for ceramics, insulators and electrodes. The physical spacing and size of the air gap also affects the air flow through the DBD and the pressure differential through the DBD. These are additional design considerations in the air handling that should be considered.

[Electric activation of DBD]
Filamentous and / or glow NTPs in the DBD are formed when a high voltage alternating current is applied between the “hot” electrode and the “ground” electrode. This alternating voltage must be between about 1,000 volts and about 150,000 volts or more. The frequency should be between about 30 Hz to about 50 MHz, depending on the application, cell shape, and desired NTP field spacing and type. Alternately, the applied power may be a bipolar pulse, the pulse rise time is any of 10 nanoseconds to 500 microseconds or more, and the pulse duration is the rise time. May be equal to or longer than 900 microseconds, and the corresponding fall time is similar to the rise time, after which the same rise time is the reverse of the same or similar voltage power characteristics. Following the polar pulse, the off period is such that the number of repetitions for the exposed NTP area on the electrode surface ranges from 0.01 to 1,000 joules / second per square centimeter. The system may be supplied with a DC bias by alternating combinations of positive and negative pulses to produce a visible “glow discharge” NTP field between the electrodes.

A DBD assembly comprised of individual electrodes, dielectrics, frame assemblies, insulators and interconnect materials is housed in a fully encapsulated metal housing. The housing is typically stainless steel, but may be other steels that can be locked to prevent unauthorized persons from entering and can be securely grounded. All high voltage components are fully enclosed within this grounded enclosure to meet standard industrial safety regulations. The DBD assemblies may be grouped into any number of sets. If power is supplied from the same power source, monitoring the power delivered to two or more DBD assemblies can usually determine the failure, as long as the power source is a DBD in a common set. Divided into two sets. The DBD power supply accepts a normal industrial three-phase power supply. Its power is driven by a dedicated power supply that translates into the voltage, frequency and waveform necessary to operate the DBD at those designed power levels and generate the NTP fields necessary to process the compound of interest. Supplied.

[Electrical design]
The power required for the DBD to generate NTP can be supplied to the DBD at a variety of different levels. A low frequency power of 30 to 2000 Hz usually requires a higher voltage than a voltage that requires a higher frequency power. The low frequency operation usually results in the streamer discharge occupying the NTP field, which is inefficient in generating the desired reactive species for the desired electrochemical reaction. At the low frequency of 30 Hz to 2 kHz, a matching inductor on the primary side of the transformer may be required to find a resonance or harmonic point of operation, but in practice resonance is not necessary to generate a field. . At the low frequency, plasma generation is significantly inefficient because much charge energy is lost in the DBD due to charge leakage of the capacitance DBD plate. A higher frequency of 10-250 kHz provides a more uniform glow NTP field. Also, at these frequencies, power loss is minimized and an electrical matching network is required to transfer as much power as possible into the NTP field. This operating range is also operated near the electrical resonance point in order to transfer power to the NTP field with the best efficiency. Typically, when the power of the DBD assembly is supplied by a low frequency and medium frequency power system, the voltage waveform at the DBD assembly is close to a sine wave and the power output to the DBD assembly at the end is stored in the DBD assembly. Supplied by one or more step-up transformers installed in the enclosure. If the power supply is a pulsed power system, the final output may or may not be driven by a high voltage transformer, and the actual technology used depends on the demand of the pulse forming network. High frequency or pulse voltage operation results in faster voltage rise and fall times and less charge lost due to charge leakage compared to low frequency operation, and less charge loss, Since the available charge per unit power for generating the desired active species increases, the number of chemically reactive species increases.

  The power supply used, capable of driving the high voltage transformer, if used, the required frequency, waveform, voltage and current are usually placed in a separate control enclosure and the DBD enclosure Wired to a high voltage transformer placed on the body. The voltage and frequency applied to the DBD that controls the power level deployed in the DBD can be varied by a number of possible means. One of them is the control of the pulse width and frequency in a simple IGBT inverter, the phase angle or impact coefficient in the SCR power supply, or the combination of DBD capacitance and high voltage transformer inductance with impedance matching network inductance and / or capacitance. In addition, the frequency change in the case of a swept frequency IGBT power source that seeks resonance or non-resonance, the number of pulse repetitions in the pulse power supply, rapid change of shock coefficient, or other means may be mentioned. This voltage frequency combination is also sent to the primary winding (if introduced) of the high voltage transformer, which in turn is caused by the secondary winding (if inserted) of the high voltage transformer. Is applied to the DBD which has the effect of adjusting the voltage and then adjusting the level of NTP generated in the DBD. If a pulse forming network is used and no high voltage transformer is required, the pulse repetition rate will change the net power delivered to the DBD assembly. Typically, a closed PID control loop that monitors the actual power output of the power supply system is measured and may be cascaded from another control loop from the ozone sensor, or a power level that may be manually entered Controlled by set value.

Systems that use small DBD assemblies designed to handle airflows of 50 actual cubic feet per minute (ACFM) or less to about 2000 ACFM typically derive power from a single phase power supply. Usually these are not limited, but are below 5 kilovolt amperes (kVA), and some systems within this power range can also be supplied with three-phase power. Larger systems incorporating multiple parallel DBD assemblies for airflow processing from 2000 ACFM to 250,000 ACFM and higher may require power of 250 kVA or higher, and usually get power from a three-phase voltage source. Regardless of the air handling capacity, the size of the system used, and the power required for it, the net power of the voltage and joules per square centimeter of electrode surface area are in the same range in the entire system. For larger airflows and / or high power demands, multiple DBD assemblies are placed in parallel, and the airflow is split across all DBD assemblies. Also, the ground electrode of all DBD assemblies is actually connected to an electrical “earth” in order to maintain a consistent voltage profile throughout all DBD assemblies used and make the system as electrically safe as possible. Yes.

In the following accompanying drawings, the best mode presently contemplated for carrying out the invention is shown.

FIG. 1 is a side view of a DBD housing that houses a DBD cell, a high voltage transformer, air and / or gas paths to electrodes and air and / or gas paths to a DBD housing mixing region. FIG. 2 is a cross-sectional view AA of FIG. 1 and shows a plan view of the arrangement of the DBD electrode and the high voltage transformer. FIG. 3 is a DBD electrode, showing the shape of the electrode in the electrode end ceramic insulator. FIG. 4 shows the relative size of the ceramic DBD barrier to the electrode. FIG. 5 is a plan view of the DBD cell assembly, showing the assembly of the electrode, ceramic electrode insulator, ceramic barrier, spacer shim, and electrode frame from top to bottom. FIG. 6 is a side view of two electrodes, showing the shape of the electrode and ceramic end insulator and the non-thermal plasma at the electrode end when they are in the “hot” position and in the “ground” position. The overlapping is shown so that it is not formed near or within the partial insulator or electrode support frame.

A preferred apparatus of the present invention includes a housing through which at least one gas flow passes, and at least four dielectric barrier discharge NTP generation cells (DBDs) through which at least a portion of the gas flow passes. This device allows all contaminated gas to be processed to flow through the two DBD assemblies, only a portion of the contaminated gas to be processed flows through the four DBD assemblies, or No contaminated gas to be treated flows directly through the DBD assembly, but the atmosphere flows through the DBD assembly as well as the gas and is then mixed with the contaminated gas to be treated to process that gas. Can be configured. When the gas passing through the DBD cell is activated and the activated gas from the DBD cell is mixed with the gas not passing through the DBD, the gas not passing through the DBD is treated with sufficient reactivity. Contains ionized species. If the amount of contaminated gas to be processed flowing through the DBD is less than the total amount, a mixing chamber is included in the apparatus that mixes the gas flowing through the DBD with the contaminated gas not flowing through the DBD. Yes. 1-2 show a preferred apparatus, where all of the contaminated gas to be treated, only a portion of the contaminated gas to be treated, or the atmosphere passes through the DBD, but passes through the DBD. If the amount of gas to be done is less than the total amount, the gas passing through the DBD is then mixed with the contaminated gas to be treated that has not passed through the DBD to process the gas. As specifically shown in FIGS. 1-2, the atmosphere and / or a portion of the air and / or the gas to be treated (1) by the source of air sent to the fan (2) mounted on the top ) Is pushed by the air around the L-shaped blade (3), passed through a set of rectifying plates (5) via the adjustment damper (4), and pushed into the DBD cell (6). Such treated atmosphere and / or air to be treated (1) then enters the treated air and / or the mixing chamber (7) and the gas to be treated (8) leaving the mixing section. Are mixed and processed as an air and / or gas stream (9). An amount of ozone exceeding the permissible emission level is generated at the outlet of the mixing chamber and needs to destroy such excess ozone, and the NTP field needs to be excited to that extent in order to destroy VOC and / or HVOC. In some cases, an optional ozone depleting catalyst (35) is introduced into the outlet of the mixing chamber. The advantage of treating either the atmosphere or only a portion of the polluted gas in the DBD is that it is treated directly in the DBD because a small gas stream flows through the DBD, which is a large DBD. This means that the volume of air and the volume of air flow need not be as great as when the total amount of gas to be treated flows directly through the DBD. This is the usual structure when contaminants are of low concentration in a large gas stream, so the size of the system components should be handled not by the total gas flow involved. Determined by the amount and type of contaminants. If the pollutant concentration is higher, or if higher eV energy is required to oxidize and / or reduce the components of interest, or if the volume is low enough, the entire gas will pass through the NTP field. All gas may be passed through the NTP field to take advantage of the higher electrical efficiency achieved when passing.

As shown in FIGS. 1-2, the apparatus includes a main flue 7, which is the inlet end to a source of air and / or gas to be treated, such as odorous air emanating from a sewage treatment facility. 11 is connected. The flue 7 forms a mixing chamber for mixing the air and / or gas passing through the DBD with the gas to be processed flowing through it. A completely sealed housing 11 supports and fully stores high voltage components such as the high voltage transformer (10) and DBD component (6) of the device. The low-voltage electrical components and control unit, including the low-voltage part of the DBD power supply, are generally housed in another standard electrical enclosure not shown, except for the measurement instrument that should be in the DBD enclosure (11). Yes. The atmosphere or all or part of the air and / or the gas to be treated enters the device via the inlet fan 2 and flows from the regulating damper 4 through the filter 14 as indicated by the arrow 1 in FIG. Rectified by the rectifying plate 5 and passed through the DBD (6) to be excited by the NTP field where the DBD is generated. Immediately after passing the DBD (6), the air passes through the DBD insulating slide gate (15) and flows into the mixing chamber (7) where it is represented by air and / or as indicated by the arrow (8) in FIG. Mixed with the gas to be treated flowing through the chamber. The air from the mixing chamber (7) was connected to the outlet end (13) of the flue 7 for discharge into the atmosphere, as indicated by the air flow arrows (9) in FIGS. Passes to a flue (not shown). Gas mixing continues during passage through the flue. In general, a fan is provided either in the flue for extracting gas or in the supply port for pushing air and / or gas to be processed through the mixing chamber, and the device ensures that the air flow is DBD. A dedicated fan (2) for flowing into the The illustrated device includes four DBDs (6) mounted in parallel to handle the air flow through the device (FIG. 5). The partition wall (16) forms a separate inlet for each DBD, and with a separate DBD insulation slide gate (15), if one or more DBDs become non-operational, the air flow will flow to the other DBD. Can be directed to pass. The wall (17) is provided with an opening and a slide gate (18) so that the DBD (6) can be slid and moved to a predetermined position, or can be removed for maintenance (see FIG. 1). The front of the cover (19) of FIG. 1 can be removed, and as shown in FIG. 1, the power supply can be disabled in conjunction with each other, the transformer can be accessed, and the DBD parts can be removed. Like that. DBD (6a) is DBD (6) being removed.

  The housing or housing (11) and housing door (19) and mixing chamber (7) may be made of a variety of materials that are durable to process gases. Preferably, it is made of a conductive material such as stainless steel or other steel that can be reliably grounded. All high voltage components are completely sealed and locked in this grounded enclosure and are subjected to a safe grounding method that meets industry safety regulations. The DBD cell (6) rests on a ceramic platform (23) so that all electrical pathways to the enclosure at electrical ground potential are interrupted by some kind of ceramic material. .

The air flow through the inlet fan (2) and through the DBD (6) is controlled either by changing the fan speed and / or by the inlet flow damper (4) (FIG. 1). Air and / or gas entering through the inlet fan (2) is separate from the air supply in this part of the housing or housing, and is cooled by another cooling fan (21) to vent the vent (22). Will not enter the area of the high voltage transformer (10).

  In order to ensure that the air flow through each DBD is substantially equal, a rectifying plate (5) is provided that can be adjusted so that the air entering the DBD can be adjusted. In order to ensure that the air exiting the DBD mixes well with the contaminated gas to be treated, the mixing chamber (7) is actually an internal baffle that rotates the air and causes turbulence in the mixing chamber ( 20) is a large round duct. This rotation is required because the active species exiting the DBD have a short half-life concentration, and many of the faster species collapse in half within 12 inches (30.48 centimeters) of movement. In order to maximize the dispersion of the reactive species from all four DBDs in the configuration described herein, the rotation of air in the mixing chamber is similar to that in the baffle plate (20). All air is rotated so that all air is rotated to a predetermined position and is immediately in close contact with the air exiting each DBD cell assembly. While describing the air rotation scheme here, to ensure that laminar flow does not occur and to ensure that all air in the mixing chamber and duct is in rapid contact with air coming from the DBD cell assembly, It is possible to design another scheme.

  Rather than sending the atmosphere into the fan (1) and passing it through the DBD (6), the apparatus shown in FIGS. It is simple to direct a portion of the contaminated gas to be treated to the inlet fan (1). Such gas to be treated is passed directly through the DBD and then mixed with the remainder of the gas to be treated in the mixing chamber.

  It is also possible to block the inlet (8) of the flue (7) and direct the entire amount of contaminated gas to be treated to the inlet fan (2). Thus, since the total amount of gas to be treated is routed into the inlet fan (2) and passed through the DBD "hot" and "ground" electrodes, substantially all such gas is stored in the DBD. Direct exposure to NTP generated by The flue (7) does not operate as a mixing chamber in this configuration as in the previous configuration. The gas passing through the DBD performs an important function of cooling the DBD electrode. Therefore, when the gas to be treated passes directly through the DBD, care must be taken to ensure that the necessary cooling is performed on the parts that require cooling. In places where the contaminated exhaust gas to be treated is hot, it may be necessary to provide quench air to the air to be treated in order to sufficiently cool and prevent damage to the DBD components.

In general, the configuration in which the total amount of gas to be processed passes through the DBD is a VOC that can be released into the environment because the electronic activity in the NTP field helps break the molecular bonds of the compound of interest by direct electron impact and ionization. More efficient in terms of energy required to break down compounds into harmless compounds, extremely short lifetimes, higher energy radicals and atomic species, singlet oxygen and other half-lives of 200 nanoseconds or less Can be used as having an effect on the oxidation and reduction of VOC compounds and molecules. In bypass mode or partial bypass mode, direct ionization of the gas to be treated does not occur, and the most chemically active short-lived radicals have significantly decayed and have a significant number of long lifetimes. Although radicals and active species are still present, they do not aid in the oxidation and reduction of VOC compounds in the mixing chamber. If the gas to be treated requires unusually high energy to oxidize and / or reduce, such as exhaust gas, that must be incinerated to treat the gas by a method other than decomposition, The entire amount of gas must pass directly through the NTP. This is because direct ionization occurs and reactive species with the highest ionization energy level are generated, so that these compounds can be oxidized and reduced only within NTP, and their oxidation and / or reduction. This is because these states are required to break bonds that require higher energy levels.

  The actual treatment of the gas to be treated may be more efficient in terms of the energy required to neutralize the VOC compounds in the gas, if all the gas passes through the DBD, but the treated In order to supply the capacity necessary to pass the entire amount of gas to be passed through the DBD, a large amount of gas requires a large number of DBDs. Thus, in such cases, and for effective processing, where the total amount of gas to be processed does not necessarily have to pass through the NTP field, a smaller amount of air, or less gas to be processed. Can be passed through a smaller number of DBDs, and such gases are used in the treatment of residual gas by being mixed as described below.

Each DBD (6) includes a rectangular frame (24) made of a non-combustible material such as polymer concrete or a ceramic material (FIGS. 5-6). This frame accommodates and supports a plurality of alternating electrodes (25), and the electrodes with conductive tabs (26) placed on one side are placed so that they function as "hot" electrodes. When installed on the opposite side with its conductive tab, it functions as a “ground” electrode (FIGS. 5-6). Generally, the “hot” electrode is either positive or negative with respect to the “ground” electrode when energized, but the “ground” electrode is always connected to electrical ground. Electrode (25) has an end plate ceramic insulator, end type with connection tab (27) and another type of end of electrode without connection tab (28), silicone or similar It is sealed on the electrode. Since the electrode has a unique shape at the insulated end, the conductive part of the electrode does not face another electrode even at this position, even through the end insulator, and thus partially NTP field formation is prevented. The objective is to form an NTP field only where there is air and / or gas flow through the DBD, thus keeping all NTP forming components air cooled. The electrode itself is a material active as a catalyst. For example, it consists of 16 gauge thick ASTM grade 1 or grade 2 titanium, so that it retains its flat shape, but it may be another active catalyst material such as palladium or cadmium, or active as a catalyst. The material may be a stainless steel with a certain coating and the material may be selected according to the VOC to be treated or any other type of catalytically active material. The dielectric barrier plate (29) is also a ceramic of either borosilicate glass or high-purity alumina dielectric, and is disposed on both sides of the electrode with voids (30) surrounding all exposed portions of the electrode. (FIG. 5). The DBD barrier (29) is such that, at high humidity, the length and height dimensions are twice the operating voltage arc distance over which the electrodes are extended, thus providing sufficient electrical arc distance between the electrodes. Is. The DBD barrier may be coated with a catalytically active coating such as titanium dioxide to aid in the oxidation of the VOC. A Teflon spacer (31) is used to allow frame adjustment, allow thermal expansion, and compensate for some tolerance variations in the ceramic component.

  The electrical connection tab (26) is extended from the electrode through the DBD support frame so that all electrical connections are outside the region where air and / or gas passes through the DBD barrier. The electrode extending closest to the outer frame on the end side D (FIGS. 1 and 5) is the “ground” electrode, and the electrode located inside the DBD frame is the “hot” electrode.

  It has been found that when a catalytically active material is exposed in the NTP field, the VOC destruction capability of the NTP field is significantly increased. Also, because cooling both the electrode and the dielectric is important for long-term operation, the dielectric barrier and all sides of the electrode are exposed to air and / or gas flowing through the DBD barrier assembly. For maximum effect from NTP and potential catalyst, catalytically active material may be contained on the electrode itself, coated on a dielectric barrier, and ASTM grade 1 or grade 2 titanium wire Screens on DBD outlets made of catalytically active material, such as mesh (32) (FIG. 6), were also found to enhance the VOC fracture characteristics of the DBD assembly.

  The ceramic insulator at the end of the electrode is sealed to the metal part of the electrode with a sealant such as silicone to prevent the formation of water flow as a result of condensation of moisture in the air and / or gas passing through the DBD cell Has been.

The physical matching of the electrodes is such that the NTP field formed between the electrodes is limited to the region where the electrodes are directly facing through the dielectric. This shape serves to control the NTP and dissociate it from the support frame so that the frame is not damaged by the NTP field. The NTP generation region is only the region surrounded by the lines (33) and (34) in FIG. 6, that is, the region within the outer periphery of the electrode.

  The excitation of the electrodes that form the NTP field in the DBD assembly varies depending on the application. The “hot” and “ground” electrodes have opposite polarities so that the NTP is formed in the directly opposite region between the electrodes. The electrode is a sine wave, with the “hot” electrode being either positive or negative with respect to the “ground” electrode at any moment of the AC cycle, even if the ground electrode is always connected to electrical “earth” ground. It can be excited by an alternating current of either a square wave or any other waveform that would be effective. The peak voltage between the electrodes is at least about 2,000 volts, and usually ranges from about 2,000 volts to about 150,000 volts, which is determined by the actual cell shape required for any application. The The frequency is about 30 Hz up to about 50 MHz, and may be higher in some cases. Where higher frequencies are used or where the rise time pulse is fast, the rise time is about 30 nanoseconds and a short duration pulse with alternating polarity is given, after which the dielectric barrier is removed and the barrier It is possible to realize an NTP field without any.

Where all DBD power supplies are supplied by the same power supply and the current flow of each DBD assembly is monitored, any DBD assembly may use a change in current flow to represent a DBD anomaly. We found it useful to divide the DBD into four groups. In the embodiment shown in FIGS. 5 and 6, there are two “hot” electrodes, each of the four DBDs has three “ground” electrodes, and all the DBDs are powered from one transformer. However, it is routed through separate disconnects, which may be powered from an inverter that is powered by three-phase power. When these electrodes are energized, an NTP field is formed in a region directly opposed between the electrodes, that is, a region surrounded by lines (33) and (34) in FIG. The NTP field occurs at a number of possible voltages and frequencies that are higher than the voltage required to create the NTP field. For example, a 5 kHz sine wave with an effective voltage of 6 kV creates an NTP field, as does a 60 Hz sine wave with an effective voltage of 14 kV in the same DBD assembly. The density of the NTP field is an important issue for the VOC destruction efficiency, and the general literature includes two main types of filaments: a thin NTP field filament and an atmospheric pressure glow discharge with a higher NTP density. The type is listed. The highest VOC destruction efficiency is achieved when the NTP field is an atmospheric pressure glow discharge, and this state is achieved by a number of means. This includes increasing power density in the DBD electrode region, DBD capacitance and power supply and frequency, voltage and waveform electrical impedance matching. The pulse power is the best method for operating the DBD because it has the effect of increasing the number of various reactive species compared to that produced with simple sinusoidal power. In general, in order to generate the desired reactive species to the maximum from the NTP field, it is desirable that the rise time of the voltage be fast in order to generate “avalanche” of the movement of electrons across the airspace in the DBD. A sinusoidal power lower than (approximately) 10 kHz has a relatively slow rise time. When the rise time is delayed, charge “leakage” occurs across the DBD barrier and does not contribute to the formation of reactive species. At frequencies below 10 kHz, the loss is very important in that only a portion of the power delivered by the inverter to the high voltage transformer and DBD combination actually generates the necessary reactive species. In low power systems up to 5 kW, even if power consumption is lost by 50%, in terms of what actually generates reactive species, it is not so important in terms of surplus heat, efficiency loss and parts cost Not to mention, this design includes device designs ranging from 5 kW to up to 100 kW or more for one system, including the possibility of multiple 100 kW systems used in large scale applications. Yes. Above 50 kW to 100 kW, some of the component costs of the power supply transformer and support system for power delivery and component cooling are less than the system combined with correct impedance matching, as well as the waste heat loss in the DBD barrier itself. It must be designed at a more efficient operating point where high frequency operation and low loss dielectrics are utilized. Paying attention to such details can significantly reduce losses, thus greatly reducing capital and operating costs and achieving the same electrochemical efficiency.

  A good power supply includes a single transformer 10 for all DBDs, which derives power from a frequency inverter that can drive the load. The impedance matching network, which may or may not include additional inductive and / or capacitance in either the transformer primary or secondary circuit, is such that the total inductive reactance of the transformer and the additional inductor is DBD “ The system will operate at “approximate” electrical resonance to approximate maximum “capacitance” capacitance, and therefore to deliver maximum power to the NTP. The term "energized" capacitance, like the "hot" and "grounded" electrode capacitances, is assembled in their frame and measured when the system is not powered. Is required because it is different from the case of measuring during operation. This is because the NTP changes the capacitance of the operating DBD. Thus, to achieve the desired NTP level, the capacitance must be matched by the operating inductance and frequency.

The inverter that powers the transformer is usually controlled by a programmable logic controller (PLC) system that monitors all current in the DBD ground line, selects the maximum current, and modulates the signal to the inverter. The power supplied by the inverter is controlled to the input set value. Variations in gas during processing such as temperature, humidity, and effects of heating parts (transformers and inductors) can cause variations in generated NTP and power consumption, which is calculated by PLC Is stabilized by a modified PED control algorithm. To further control the plasma, current monitoring in each DBD assembly grounds the current server and indicates if any of the DBDs fail. All operate at similar power and the difference should be only a few percent. If even one of the DBDs suddenly has different power, this is a sign of a DBD failure, and the system must be shut down to warn necessary maintenance personnel to avoid excessive damage to the DBD parts. Can do. In another configuration, the three-phase output is used to drive three individual transformers with the primary side of the transformer connected in a triangle to the secondary connection of each transformer on a single DBD assembly. If one of the DBDs fails, it can be detected by monitoring each output phase of the inverter and then using a contactor in series with the primary side of each transformer to activate the failure phase stop. Displayed by phase imbalance.

  The power supplied to the primary side of the transformer by the inverter varies depending on either the operating frequency of the inverter or the width of the pulse sent from the inverter to the transformer. Via an algorithm, this then adjusts the voltage output of the transformer to a “hot” electrode and a “ground” electrode that adjusts the level of NTP produced. Such control is typically very non-linear, but in a resonant mode where the system typically has a higher current flow than the inverter that powers the system at the DBD capacitance and inductance of the system. This is because it works. Typically, a closed PID control loop where the actual power output of the inverter is monitored is measured and controlled to a power level setpoint that can be cascaded from another control loop from the ozone sensor, or the setpoint is entered manually I can do it. Other system status relative to input power to the inverter, such as contactor status, inverter output current and / or other DBD ground current is also monitored and displayed by the PLC system. An important interlock monitored by the PLC is the DBD pressure differential, which represents the air and / or gas flow flowing through the DBD. Typically, two hot electrodes with three ground electrodes in each of the four DBD assemblies, in this particular embodiment, at least 70 ° F. (about 21.11 ° C.) for each DBD assembly. 1000 ACFM of gas is required, for a total of 4,000 ACFM. In this embodiment, this creates a pressure difference of 0.8 inches of water at 4000 ACFM. The gas must be filtered to such an extent that coarse particles and debris that may not pass between the gas flow spaces separating the “hot” and “ground” electrodes are removed. If there is insufficient air and / or gas passing through the DBD due to filter clogging, system fan failure, or any other reason, this is represented by a drop in pressure differential, which is detected by the PLC. , Stop power to this unit, display this and issue a warning. This is necessary or else the DBD is overheated to separate the electrodes, and the dielectric breaks, which can destroy the dielectric integrity, leading to malfunctions.

  The rated power of this embodiment described is 15 kilowatts, measured as a power input to an inverter that is not necessarily dissipated in the DBD. The loss can be reduced considerably, so that the financial and operating costs can be greatly reduced and the same electrochemical efficiency can be obtained.

  Other embodiments are possible by changing the size of the DBD, the number of DBD electrodes in the DBD assembly, airflow, power density, and power rating. For example, using power from 5 watts to about 3000 watts, single phase units for small airflows are possible. In systems that require more power, power is usually supplied with three-phase power. Some have power electronics of the type, have SCR control and another IGBT configuration, and are available with higher frequency power supplies.

  There is a need to reduce VOCs that may or may not have odorous components. It is important to consider the following when choosing power and gas flow designs for implementation in a particular application:

  X The wide range of properties of various VOCs, their odor intensity, perceived odor characteristics, and the specifics required for the oxidation and / or reduction of any mixture of VOC complex organic molecules and / or HVOC Due to the scientific uncertainty of determining composition, effectiveness, and energy, the size of the system when applied to an unknown VOC is to run a pilot scale system in the odor field. Decide on.

  X The pilot scale system is operated with a conventional VOC-carrying air stream that is the same in all flow paths as the full scale system and is reduced in scale. With an emitted, odorless or non-odorous air flow, the system responds to adjustable power and frequency levels to optimize the operating mode, residence time and joules / liter required for gas processing. To determine the density, it is operated with various forms of air flow.

  X The proper mixing and flow of VOC-air and / or non-VOC contaminated air into a pilot scale system is determined by the nature of the VOC and may be determined by the intensity and character of the odor. Odorous air if the VOC is highly concentrated and possibly cannot be processed by any other means except incineration, or if the entire volume of air flow contaminated with VOC can pass through the DBD cell Is best designed to pass through the DBD assembly because it has the highest energy and efficiency effects.

  In applications where the X VOC is diluted and does not need to be neutralized directly through the DBD and / or where the airflow is high, the system will remove some of the contaminated air and / or airflow. It may be best to pass the DBD through the desired mixing ratio and inject the active species formed by the DBD assembly from this air into the odorous air stream for treatment.

  X In applications where extremely high concentrations of VOCs, or VOCs that are difficult to oxidize and / or reduce, need to be processed, only the most active species active only in the NTP field are such difficult VOCs. In order to neutralize, the entire amount of VOC must be passed through the DBD assembly and must be processed directly by the NTP field. In such applications, low-level VOCs should be treated to some extent from other airflows, such as ambient air in the factory, because even a small amount of reactive species may remain in the air excited by the DBD. Are useful and they are put into the odor removal system through the DBD bypass input. In this configuration, a pilot-scale and full-scale odor removal system processes both odor sources simultaneously.

  X It is also possible to have multiple DBD assemblies operating in series. That is, the air flow is routed through one DBD assembly and passed through the NTP field, then (if possible) after being passed over the catalyst mesh under the first DBD assembly and then another. Is passed through the second DBD assembly and (if possible) through the second catalyst mesh, etc., from the second NTP field to provide multiple NTP catalyst treatments for a particular air flow. Once an energy level of an air flow rate is established for each system input for a particular odor source or combination of sources, the size of the full scale system can be determined.

  The system illustrated in FIGS. 1-2 is in a bypass system configuration and uses either 4000 real cubic feet per minute (ACFM) of air or contaminated air through the DBD. This is activated by NTP to generate reactive species that mix with the gas to be treated. The volume of gas being processed will be between 1000 ACFM to 50,000 ACFM per assembly, depending on the concentration of VOC that needs to be processed (multiple assemblies may be used in large scale applications). Even in this same configuration, a portion of the gas to be treated flows through the NTP field, allowing the gas in the mixture to pass. In this configuration, the gas passing through the NTP field is not only processed to remove the contaminants of interest, but is also activated to process other air.

  A further feature of the present invention is that for some VOCs, the efficiency of VOC destruction removal can be directly monitored and automatically controlled using an ozone monitor. Ozone is one of the long-lived reactive oxygen species formed to treat odorous gases, and is odorous when enough species are created to neutralize VOC levels. In cases where VOCs, which may or may not be, can be treated with long-lived species, usually a small amount of ozone remains in the treated gas stream. The power given to the DBD controls the amount of active species produced (within the limits of the DBD power rating), so the power is automatically modulated to meet Environmental Protection Agency (EPA) or local government guidelines. A low level of residual ozone can be maintained. By adjusting the power to the DBD, the NTP level is controlled, thus adjusting the amount of active species produced and thus the level of active species required to handle the combined gas flow and contaminant levels Thus, the VOC contained in the gas stream is completely oxidized and / or reduced, and sufficient active species are produced so that a small amount of ozone remains in the effluent. If a small amount of residual ozone falls, it means that the VOC to be processed is increasing, so the automatic control loop increases the NTP field by increasing the power to the DBD, In response, more active species can be generated to meet processing requirements. When the residual ozone increases, the VOC load decreases, so the power to maintain a small amount of residual ozone set by automatic control is reduced to stay within the authority's ozone emission limits. If all of the gas to be processed must pass through the NTP field for effective processing, the VOC that requires processing requires high energy, so the gas being processed consumes low-energy ROS species. However, because ozone is a member of it, it may not be possible to close the control loop using ozone as a working variable. In such cases, a manual operation level is required to set.

  The aforementioned programmable logic controller (PLC), which interlocks all safety devices and controls the on / off and adjustment functions of the devices, also incorporates system interlocks according to factory demand. In other words, the controller automatically shuts down when the factory stops production and / or the system fails, isolates the fault and issues an alarm message.

  The system of the present invention may be added to an existing factory or may be incorporated as part of a new plant design. Changes in equipment due to the introduction of this technology into the factory are minimal, and the only goods consumed for operation are electricity and occasional filter replacement. The catalyst component is not consumed in this system. In addition, this technology is the largest release of odorous or non-odorous tens of thousands of ACFM containing VOC pollutant air into the environment from small home sized devices for odors from point sources such as several ACFM. It can be scaled to any size up to the factory. If large amounts of air and / or extremely high VOC loads must be processed in combination with large amounts of air, multiple units can be combined in parallel to handle the air.

Although the present invention has been described as an apparatus for the treatment of volatile organic compound contaminants in gas exhausts, the present invention can also be used to oxidize and / or reduce a single target compound or a plurality of target compounds. It can be used for various purposes. One such application is to reduce the hydrocarbon content in air exhaust applications to an acceptable level before being released into the atmosphere. Combustion and other gas fumes, smoke from oil wells or other operations, and fine particulate emissions such as H ₂ S are, in other methods, burned or flared before being discharged into the atmosphere. Although necessary, it can be oxidized and reduced using this technique. If the concentration of combustibles in the gas to be released is below the ignition point, additional fuel such as propane is often required to keep the flare burning. With this technique, the ignition concentration is not required to completely oxidize and reduce the gas, and the gas to be treated by the NTP can be completely oxidized and reduced regardless of the hydrocarbon level. Other hydrocarbon compounds, such as those containing chlorine and fluorine, can also be treated according to the present invention.

  In the present specification, the present invention is illustrated and described with reference to an embodiment which is considered to be the best mode of carrying out the present invention in actual practice at present. However, in adapting the present invention to another embodiment, The possibility of using improved materials (e.g., power supplies or ceramics) is subject to various modifications without departing from the superordinate inventive concept disclosed herein and understood by the following claims. It goes without saying.

Claims (12)

  A processing device for volatile organic compounds (VOC) and / or halogenated volatile organic compounds (HVOC), some of which may or may not be odorous and / or air and / or Or a processing apparatus comprising organic fine particulate contaminants in a gas exhaust and comprising: a planar dielectric barrier discharge (DBD) non-thermal plasma (NTP) generating cell having a gas flow path therethrough An assembly, wherein the cell has a plurality of electrical hot and ground electrodes that are alternately positioned opposite one another, and the air and / or gas flowing in the gas flow path is between these electrodes. Located in the air and / or gas flow path so that it flows through the airspace, all electrodes are made of a catalytically active material or active as a catalyst The dielectric material is either coated with a material, and the dielectric material separates the electrodes to prevent direct arcing between the electrodes with an alternating voltage potential difference during operation and sufficient power is applied. The AC voltage potential difference is activated to cause the DBD to generate an NTP field, and various reactive species in various states of low, medium and high ionization, namely reactive oxygen species (ROS), hydroxyl species, molecular species and A dielectric barrier discharge (DBD) specific thermal plasma generating cell assembly that generates atomic species and wherein the dielectric barrier may be coated with a catalytically active material; of the cell leading to the gas flow path through the cell; A gas inlet; and through the cell and further through a mesh having activity as a catalyst for the DBD outlet where the gas needs to pass (possibly Of some), the gas outlet of the cell for discharging the gas.   A portion of the gas exhaust may be odorous and / or contain VOC and / or HVOC that may contain organic fine particulate contaminants, the gas injection of the DBD assembly. The inlet is connected to a source of air and / or gas exhaust, and the gas outlet of the DBD assembly is treated for exhaust after being treated with the reactive species generated by the NTP The processing apparatus of Claim 1 which discharges air and / or gas.   A VOC and / or HVOC treatment device that may be odorous and / or contain organic fine particulate contaminants in the gas exhaust, said air and / or treatment The remainder of the gas to be processed is divided from the whole of the air and / or the gas to be processed, passed through the DBD cell and activated by the NTP field of the air and / or the gas to be processed. A portion of the gas that includes a gas mixing chamber that can be mixed with a portion, so that a portion of the air and / or gas is treated and not passed through the DBD cell in the mixing chamber immediately after the DBD cell Because some of the air and / or gas is partly due to the extra reactive species being produced. Is also processed, the mixing chamber gas outlet, the processing apparatus according to claim 2 for discharging all the air and / or gas mixture and treated for can discharge through conduit is passed through the device.   VOC and / or HVOC treatment equipment that may be odorous and / or contain organic fine particulate contaminants in a portion of the gas exhaust, each cell having multiple alternating currents The DBD cell assembly comprised of potential electrodes is either comprised of a catalyst carrier conductor or is coated with a catalyst material separated by a dielectric that may or may not be coated with a catalyst material. The processing apparatus according to claim 3, wherein the processing apparatus is held in place by a non-conductive frame, and a large number of cells are arranged in parallel for processing a large amount of air flow.   A VOC and / or HVOC treatment device that may be odorous and / or contain organic fine particulate contaminants in a portion of the gas exhaust, wherein excess ozone is present in the exhaust and If present in the gas to be treated, the exhaust and / or gas is an additional catalyst for the production of more gaseous catalytic reduction reactions and possibly for the destruction of excess ozone. The processing apparatus according to claim 4, which may be sent to a support or to a two catalyst support system.   A VOC and / or HVOC processing apparatus, wherein a portion of the gas exhaust may be odorous and / or may contain organic fine particulate contaminants, the electrode and the DBD assembly The assembly that grips the dielectric forming the substrate uses alumina or borosilicate glass as part of the dielectric material, and part of the ceramic material is polymer concrete specifically designed for high voltage insulator applications The processing apparatus according to claim 5, wherein a part of the insulating material is Teflon or another non-metallic insulating material.   A VOC and / or HVOC treatment device that may be partly odorous and / or contain organic fine particulate contaminants in the gas exhaust, wherein the electrode of the DBD is Alternating hot electrodes, either composed of a catalytically active material, or coated with a catalytically active coating, separated by a dielectric barrier spaced in the middle of the surface of said electrode And between the electrode and the dielectric barrier, there is a gap in the range of 0.1 mm to 25.0 mm between the electrode and the isolation dielectric, This can be between 0.5 mm and 10.0 mm thick, and the hot electrode, the dielectric barrier, the ground electrode, and the dielectric barrier are spaced apart at equal intervals. Both ground electrodes are exposed to the air to be treated so that catalysis of the electrode and, if possible, the dielectric barrier can have a maximum effect, the electrode creating a capacitor 7. The processing apparatus according to claim 6, wherein the NTP field is generated between the surfaces of the opposing electrodes when electrically excited as necessary because of the positional relationship of parallel plate arrangement.   A VOC and / or HVOC processing device that may be odorous and / or contain organic fine particulate contaminants in a portion of the gas exhaust, wherein the electrode is in place The electrically insulating material to be carried is a ceramic material, and the dielectric separating the electrodes is located on the entire plane beyond the electrodes even when the electrodes are gripped in alignment with the cell assembly. Extended to the side, so that the distance covered by the electric arc is maximized, the air gap is used to complement the insulating properties of the insulating material, the end of the electrode is cut into an offset mold, Their ends do not oppose where they are held in place in the electrode end insulator near the DBD support frame, so that the ends are Formation of the NTP field in the vicinity of the end of the electrode held in place by the support frame is prevented, and the NTP field does not contact the support frame and separates the surfaces of the opposing electrodes. 8. The processing apparatus of claim 7, wherein the electric arc travel distance between the hot electrode and ground electrode around a ceramic dielectric barrier is maximized to prevent a short circuit of the electric DBD capacitor assembly circuit.   VOC and / or HVOC treatment equipment that may be odorous and / or contain organic fine particulate contaminants in the gas exhaust, where power is applied to the electrodes Then, an NTP field is generated between the electrodes, and an outer periphery of the hot electrode is substantially equal to the outer periphery of the hot electrode, and defines an outer periphery of the NTP field generated between the electrodes. The processing apparatus according to claim 8, wherein the processing apparatus is separated from the frame and from the individual electrode support insulators.   A VOC and / or HVOC treatment device that may be odorous and / or contain organic fine particulate contaminants in a portion of the gas exhaust, providing power to the electrodes To generate a “glow discharge” rather than an “NTP filament” of the “filament discharge” between the electrodes, and the power is an AC voltage of about 1000 volts to about 150,000 volts at a frequency of about 30 Hz to about 50 MHz. Alternately, the applied power may be a bipolar pulse, the pulse rise time may be anywhere from 10 nanoseconds to 500 microseconds, and the pulse duration may be equal to the rise time, Alternatively, it may be as long as 500 microseconds, and the corresponding fall time is the same as the rise time, and then the same fall time as above. Rise time is followed by reverse polarity pulses with the same or similar voltage power characteristics, and the off period is such that the repetition rate corresponds to a range of 0.01 to 1,000 joules / second per square centimeter 10. Alternately, the system may be supplied with a DC bias by a combination of positive and negative pulses to produce a visible "glow discharge" NTP field between the electrodes. The processing apparatus as described.   A VOC and / or HVOC processing apparatus, which may be odorous and / or may contain organic fine particulate contaminants, in addition to the dielectric A barrier discharge NTP generation cell power control system, and a sensor of ozone in the treated gas emitted from the apparatus, the ozone sensor displaying an indication of the ozone content of the treated gas. And the ozone content of the treated gas indicates the degree of treatment of the gas, and the indication of the ozone content of the treated gas is proportional to the first part of the control scheme. Sent to the control system to control the power supplied to the cell with a differential (PID) type controller and supplied to the ozone outlet concentration and the DBD. Using a restriction on the power that can be done, a secondary control scheme is programmed to reduce the ozone below a set value and pass the DBD if the plasma power is at the design maximum Passing through the DBD and NTP fields, which can reduce the air flow and indicate that enough active species have been generated in the air and / or gas to completely destroy the target pollutant The residual ozone of the air and / or gas is always controlled, and the control scheme ensures that the air never passes through the NTP field and needs to be reduced. (Plasma field power modulation) can only be included or residual ozone in all possible cases of any application In situations where it may be necessary to change the air flow through the NTP field to ensure, plasma power modulation in the first part of the control scheme and then in the second part of the control scheme The processing apparatus of claim 10, which may be a split control scheme that includes both airflow modulation.   A VOC and / or HVOC treatment apparatus that may be odorous and / or may contain organic fine particulate contaminants in a gas exhaust, comprising: Apparatus: One or more dielectric barrier discharge (DBD) non-thermal plasma (NTP) generating cells connected in series and / or in parallel and / or in series-parallel, having a gas flow path therein, It has a plurality of electrically hot electrodes and a ground electrode, both of which are electrically conductive and are made of a catalytically active material or are coated with a catalytically active material, each alternating Since the hot electrode and the ground electrode are separated by a dielectric barrier, a non-thermal plasma is generated when electrically excited, and the electrode is located in the gas flow path. A gas that flows in the gas flow path to create a field flows through the airspace between the electrodes and passes through the NTP field formed between the dielectric barrier and the electrode plate. Discharge (DBD) non-thermal plasma (NTP) generating cell; gas inlet through the DBD cell to the gas flow path; DBD cell gas outlet for discharging gas that has passed through the DBD cell; DBD cell gas exhaust A gas mixing chamber having a first section and a second section gas inlet for a gas inlet connected to an outlet, wherein the mixing chamber mixes gases entering the chamber from first and second inlets A gas mixing chamber; and a mixing chamber gas outlet for discharging the gas that has passed through the mixing chamber, The mouth is arranged such that the cell gas inlet is selectively connected to a source of contaminated gas to be treated, an air source, or both a contaminated gas and air source Mixing, which may have additional catalytic material to facilitate the redox reaction of the mixing chamber and then increase the likelihood of an ozone destruction catalyst further downstream of the air and / or gas stream Chamber gas outlet.

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