JP2007501349A - Apparatus for reducing contaminants in a fluid stream with a dielectric barrier discharge excimer lamp - Google Patents

Abstract

  An apparatus for reducing contaminants in a fluid stream. The apparatus includes at least one light source to generate a base energy to generate a group in the fluid stream, the light source being a dielectric barrier discharge excimer lamp.

Description

  The present invention relates to an apparatus for reducing pollutants in a fluid stream, and preferably to an apparatus for reducing pollutants in exhaust gas produced by fuel combustion.

  A lamp conventionally used to provide such a treatment is a low-pressure mercury lamp that emits vacuum ultraviolet radiation at a wavelength of 185 nm, which is the resonance line of mercury. Such constant pressure mercury lamps are described, for example, in US Pat. No. 6,047,543 and International Application No. PCT / US / 96/20581.

  US Pat. No. 6,047,543 discloses an apparatus and method for increasing the chemical reaction rate in a gas stream. The apparatus has at least one heterogeneous catalyst having an upstream end and a downstream end and at least one surface having a plurality of catalytic active sites, wherein the catalyst is such that at least a portion of the gas stream is a catalyst on the surface. Located in contact with at least a portion of the active site. At least one device for generating groups or other active species from at least one water vapor or other gaseous species, such as a corona discharge device or an ultraviolet source, is used to generate groups or other active species. , They are introduced into the gas stream upstream of the downstream end of the catalyst. Groups or other active species are introduced in an amount sufficient to reduce or eliminate catalyst poisoning by catalyst poisons, such as sulfur, sulfur, including compounds, phosphorus, phosphorus, including compounds, and carbon. Is done.

  International Application No. PCT / US96 / 20581 discloses a method and apparatus for reducing pollutants in exhaust gas produced by an internal combustion engine. In one embodiment, ozone generated by ultraviolet radiation having a wavelength of 185 nanometers is introduced into the intake of a combustion engine to provide more complete combustion reduction, increased efficiency, and fewer pollutants. The In other embodiments, ozone is introduced into the mixed gas stream, after which the exhaust gas is processed by a catalytic converter, so that only pollutant is used compared to when only the catalytic converter is used to process the exhaust gas. Further savings are obtained. In a different embodiment, a method for reducing pollutants in exhaust gas generated from combustion of fuel by introducing hydroxyl into the exhaust gas stream upstream of the catalytic converter and treating the exhaust gas with the catalytic converter And an apparatus are provided.

  However, mercury (Hg) low pressure discharge lamps have the disadvantage that their efficiency is highly dependent on high temperature. Furthermore, the problem of the presence of Hg for the environment is well known. These lamps are undesirable for automotive applications because the application of harmful components such as Hg should be avoided. Also, Hg low pressure discharge lamps have a significant risk of exhibiting material fatigue that can lead to Hg release. Hg release can adversely affect the catalytic activity of metal-based catalysts. However, the presence of catalyst poisons that can be absorbed on any catalyst surface of the fuel, oxidant, or reaction product degrades the performance and efficiency of the catalyst process by occupying active sites on the catalyst surface. This, for example, reduces the number of sites available for fuel and oxidant and reduces the reaction rate.

  Accordingly, there is a need for a simple, clean, inexpensive light source that has a long lifetime and maintains the efficiency of the device in order to reduce contaminants in the fluid stream and avoid the above disadvantages.

  Accordingly, it is an object of one embodiment of the present invention to provide an apparatus for reducing contaminants in a fluid stream.

  Another object of the present invention is to provide pollutants in combustion engine exhaust gases, preferably in vehicle exhaust gases such as automobiles or trucks using fuels such as gasoline, methanol and / or diesel. To provide a device for reducing the engine intake valve so as to provide more complete combustion of fuel and increased efficiency without the need for major changes to the internal combustion engine or catalytic converter. Upstream, radiant energy is used to convert oxygen in the air to ozone.

  A further object of one embodiment of the present invention is to provide an apparatus for reducing pollutants in a fluid stream, such as hydrogen, methanol, oxygen, or the like, for fuel cells. It is.

  The object according to the present invention is solved by a device for reducing contaminants in a fluid stream, which device comprises at least one light source for generating radiant energy to generate groups in the fluid stream. The light source is a dielectric barrier discharge excimer lamp.

  The fluid stream may be a gas stream or a liquid stream, preferably the fluid stream is a gas stream.

  The dielectric barrier discharge excimer lamp used according to the present invention is anhydrous silver.

  The use of a dielectric barrier discharge excimer lamp to reduce contaminants in the fluid stream is preferred for the following reasons. That is, the light output is constant between −150 ° C. and + 500 ° C. and / or has a long product life even due to a fast switching cycle and / or rapidly increases to full output power and / or Enables fast switching cycles, reduces warm-up problems, and / or relaxes geometric constraints and allows for better integration into the system.

  A dielectric barrier discharge lamp generates excimer light emission by including a gas for excimer light emission in a discharge vessel made of a dielectric material to cause a dielectric barrier discharge. Such a dielectric barrier discharge lamp may have a hollow cylindrical discharge space made of quartz glass that is at least partially dielectric and filled with a gas for excimer emission.

  Furthermore, the apparatus of the present invention may include a transformer for driving at least one light source and / or a connector for connecting the transformer to the electrical system of the engine.

A dielectric barrier discharge (DBD) lamp source generates UV / VUV output from excimer molecules. If pulsed high voltage AC drive is used, a high electrical efficiency of at least ≧ 20%, preferably ≧ 30%, more preferably ≧ 40% is achieved for the xenon (Xe) excimer discharge. In a dielectric barrier discharge lamp structure, one or both electrodes are separated from the plasma by an insulating dielectric layer, and the discharge is a series of short-lived narrow filamentary paths and / or microdischarges that occur probabilistically in time. Consists of. Although most dielectric barrier discharge lamps are traditionally powered using an alternating voltage waveform, according to the present invention, short pulse excitation can have significant advantages. Specifically, the dielectric barrier discharge lamp efficiency for generating VUV from a Xe ₂ ^* lamp (172 nm) is fast excitation with a duration of ≦ 1 microsecond (μs) following a rest period of about 100 microseconds (μs) Compared to alternating current excitation by using pulses, it can be dramatically increased by a factor of at least 2, preferably 3 or more.

  According to the present invention, the duration of the excitation pulse is ≦ 1000 microseconds and ≧ 100 nanoseconds, preferably ≦ 500 microseconds and ≧ 1 microsecond, more preferably ≦ 100. Microseconds and ≧ 10 microseconds.

  The rest period according to the present invention is ≦ 10000 microseconds and ≧ 1 microsecond, preferably ≦ 1000 microseconds and ≧ 10 microseconds, more preferably ≦ 100 microseconds. And ≧ 10 microseconds.

  The output is generated with short pulses of higher peak power from uniform or micro discharges that appear as conical or fan-shaped structures rather than narrow filaments.

  The emission spectrum and efficiency of the dielectric barrier discharge depends on the filling gas, so that several wavelengths between 126 and 351 nm can be obtained, as displayed in Table 1.

(Table 1)
Peak emission wavelength and efficiency of dielectric barrier discharge lamps for sinus drive as a function of fill gas

  The efficiency of the Xe excimer discharge lamp exceeds ≧ 40% and is therefore particularly suitable.

To optimize the effects within the specific reaction being targeted, the spectrum can be further modified by one or more phosphors applied to the inner surface of the quartz tube, if necessary. For example, for efficient decomposition of benzene, it is widely applied up to 2% by weight as a component in fuel using radiation in the range of 180 nm to 210 nm. This wavelength range can be addressed by Nd ³⁺ active phosphors.

Radiation with a wavelength of less than 240 nm accessible by Pr ³⁺ phosphorus can cleave NO _x present in the combustion engine exhaust. Efficient UV-C emitting phosphors for Xe excimer discharge lamps are, for example, LaPO ₄ : Pr, YPO ₄ : Nd, YPO ₄ : Pr, LuPO ₄ : Pr, YPO ₄ : Bi.

  The phosphor itself acts as a functional surface component, which is then applied to the inner surface of the converter structure and functions under illumination using the lamp. In other words, the catalyst surface layer is then additionally activated by light from the lamp.

  This type of catalytic converter of the present invention can be used for many purposes. Most preferred is the use in passenger cars with combustion engines, in which case it can greatly enhance efficiency and safety over existing solutions.

By using a dielectric barrier discharge lamp according to the present invention, ionization of groups prior to reaction by ultraviolet light significantly increases these reactions occurring in the converter compared to Hg low pressure discharge lamps. In order to reduce pollutants and foreign substances, hydroxide ions “OH” and other free radicals and oxidants such as O, H, HO and H ₂ O ₂ are generated in the fluid stream. obtain. In addition, oxygen in the fluid stream is converted to ozone by the dielectric barrier discharge lamp, which increases the combustion efficiency of the engine fuel in the fluid stream, thereby allowing hydrocarbons in the fluid stream, such as hydrocarbons and monoliths in the exhaust gas. Reduce the amount of carbon oxide (CO).

For example, these groups can be generated and introduced into the combustion gas stream of a combustion engine to reduce pollutants and foreign objects such as CO and hydrocarbons. OH in the presence of oxygen rapidly reacts with CO, it has been observed to generate CO _2. OH in the presence of oxygen reacts rapidly with hydrocarbons to formaldehyde or other similar intermediate products, which then react with OH to form H ₂ O, CO ₂ and HO. It was observed. Moreover, there is evidence that the series of reactions do not disappear, but rather regenerate OH.

  The OH and other related free radicals and oxidants produced in the reaction can be used as catalysts independently of or in conjunction with the normal catalytic function of noble metal particles such as Pt, Pd, Rh and combinations thereof in catalytic converters. Can work.

Catalyst noble metal particles such as Pt, Pd, Rh, and / or combinations thereof are preferred. However, as the catalyst material, titanium dioxide _(TiO 2), preferably, TiO ₂ porous structure may also be used. The porous structure should be selected to allow fluid flow to pass through.

  According to an embodiment, the apparatus of the invention comprises at least one heterogeneous and / or homogeneous catalyst having an upstream end and a downstream end and at least one surface having a plurality of catalytic active sites, wherein the catalyst comprises a gas At least a portion of the stream is positioned to contact at least a portion of the catalytically active sites on the surface.

  The dielectric barrier discharge excimer lamp used in accordance with the present invention preferably contains a fill gas selected from the group of argon, krypton and / or xenon, preferably xenon. The filling gas may further include a halogen gas such as phosphor (Fluor) and / or chloro (Chlor).

  The filling gas pressure of the dielectric barrier discharge excimer lamp used for the present invention can be between 50 mbar and 600 mbar. This filling gas pressure is measured at room temperature.

The dielectric barrier discharge excimer lamp is based on the total weight of the filling gas in the dielectric barrier discharge excimer lamp, and the total filling does not exceed 100% by weight of the total weight of the filling gas in the dielectric barrier discharge excimer lamp. ,
-0 wt% to 100 wt% argon, preferably 10 wt% to 90 wt% argon, more preferably 20 wt% to 80 wt% argon, and / or
-0 wt% to 100 wt% krypton, preferably 10 wt% to 90 wt% krypton, more preferably 20 wt% to 80 wt% krypton, and / or
-0% to 100% neon, preferably 10% to 90% neon, more preferably 20% to 80% neon, and / or
-0 wt% to 100 wt% xenon, preferably 10 wt% to 90 wt% xenon, more preferably 20 wt% to 80 wt% xenon,
The lamp can also include a mixture of the fillers, wherein the sum of the fillings does not exceed 100% by weight of the total weight of the filling gas in the dielectric barrier discharge excimer lamp. .

More preferably, the dielectric barrier discharge excimer lamp comprises a phosphor material, and the phosphor material is YPO ₄ : Nd, YPO ₄ : Bi, YPO ₄ : Pr, LuPO ₄ : Pr, and / or LaPO ₄ : It is preferably selected from the group of Pr, more preferably selected from a mixture thereof.

In order to improve the reduction of pollutants in the fluid flow, dielectric barrier discharge excimer lamps
Between -150 nm and 200 nm, preferably between 160 nm and 190 nm, more preferably between 170 nm and 180 nm, or
Between −160 nm and 230 nm, preferably between 170 nm and 210 nm, more preferably between 175 nm and 190 nm, or
Between −220 nm and 250 nm, preferably between 225 nm and 249 nm, more preferably between 230 nm and 248 nm,
It is desirable to have a maximum emission luminance or maximum peak at a wavelength of.

  These and other objects, advantages and features of the present invention will become apparent from the following drawings which illustrate the invention.

  According to a first embodiment of the present invention, an apparatus for reducing contaminants in a fluid stream comprises a combustion chamber comprising a pre-combustion gas flow to the combustion chamber and a post-combustion exhaust gas flow from the combustion chamber. And at least one dielectric barrier discharge excimer lamp is located in the pre-combustion gas stream.

  According to a second embodiment of the invention, a normal converter is used and then modified to accommodate a dielectric barrier discharge excimer lamp that needs to be placed in front of the converter structure. Exhaust gas flows around a dielectric barrier discharge excimer lamp that emits ultraviolet light, which breaks the binding of the incoming molecules of the fluid stream and releases the fluid stream of ionized material, which reacts in the second zone and produces the desired Become product.

  According to a third embodiment of the invention, the device for reducing contaminants in a fluid stream has at least one sensor. Sensors may be used to control and / or regulate fluid flow rate, fluid contaminant loading, and / or dielectric barrier discharge excimer lamp function. For example, if the first dielectric barrier discharge excimer lamp malfunctions, the second dielectric barrier discharge excimer lamp can be activated. Depending on the contaminant loading of the fluid, it is also possible to activate a number of dielectric barrier discharge excimer lamps, preferably at least two, more preferably at least three dielectric barrier discharge excimer lamps.

According to a fourth embodiment of the present invention, there is provided an apparatus including a dielectric barrier discharge excimer lamp inserted in a container, which is connected to a feed tube. Container further comprises a porous structure of TiO _2. The inner portion of the vessel is formed such that the incoming fluid flow first passes through the portion of the vessel containing the dielectric barrier discharge excimer lamp and then flows through the TiO2 structure. The fluid is broken down into ionic groups, which can further react to harmless groups on the TiO2 surface. The resulting fluid is discharged through the outlet of the container.

  According to another embodiment of the invention, the fluid stream is a liquid stream. An apparatus for reducing contaminants in a liquid stream includes a pre-liquid flow to a contaminant reduction chamber and a post-liquid flow from the contaminant reduction chamber, wherein at least one dielectric barrier discharge excimer lamp is Located in the apparatus, preferably in a pollutant reduction chamber.

  In order to treat the fluid stream to reduce the concentration of at least one pollutant in the fluid, preferably the exhaust gas stream from the combustion of fuel in the engine to reduce the concentration of at least one pollutant in the gas stream. For processing, more preferably, the apparatus according to the invention can be used to reduce the concentration of at least one contaminant of the fuel cell fluid.

  However, the apparatus according to the invention can be used for the purification of industrial exhaust lines, for the production of chemicals or for use as a reformer for generating oxygen on motor vehicles. Is preferred.

  To illustrate the principles of the present invention, FIG. 1 shows a xenon dielectric barrier discharge excimer lamp (2) inserted into a metal case (3) connected to an exhaust pipe system of a combustion engine by an inlet pipe (4). The device (1) is shown including: The container contains porous structure titanium dioxide (5). The interior of the metal enclosure is formed such that ingress gas moves around the lamp and then flows through the porous titanium dioxide structure. The gas is broken down into ionic species, which react on the surface of titanium dioxide and become harmless. The resulting gas is released through the outlet opening (6).

FIG. 2 is a schematic diagram illustrating an example of an ultraviolet assisted catalytic converter with a dielectric barrier discharge excimer lamp that does not have phosphor and suprasil. It is a graph which shows the emission spectrum of a UV assisted catalytic converter and a suprasil provided with the dielectric barrier discharge excimer lamp (it does not have a phosphor). (No phosphor) dielectric barrier discharge Xe ₂ ^* excimer lamp is a graph showing the emission spectrum of Supurashiru. 6 is a graph showing an emission spectrum of a dielectric barrier discharge Xe ₂ ^* excimer lamp with YPO ₄ : 1 wt% Nd. 6 is a graph showing an emission spectrum of a dielectric barrier discharge Xe ₂ ^* excimer lamp with LaPO ₄ : 1 wt% Pr. 6 is a graph showing an emission spectrum of a dielectric barrier discharge Xe ₂ ^* excimer lamp, Suprasil comprising YPO ₄ : 1 wt% Pr. 6 is a graph showing an emission spectrum of a dielectric barrier discharge Xe ₂ ^* excimer lamp, Suprasil comprising YPO ₄ : 1 wt% Bi.

Claims (10)

  An apparatus for reducing contaminants in a fluid stream, having at least one light source for generating radiant energy to generate groups in the fluid stream, the light source being a dielectric barrier discharge excimer lamp.   Having at least one heterogeneous and / or uniform medium (5) having an upstream end and a downstream end and at least one surface having a plurality of catalytically active sites, wherein the medium is at least part of the fluid stream The apparatus of claim 1, wherein the apparatus is positioned to contact the catalytically active sites on the surface.   The apparatus according to claim 1 or 2, wherein the dielectric barrier discharge excimer lamp has a filling gas with a noble gas selected from the group of argon, krypton and / or xenon, preferably xenon.   The apparatus according to claim 1, wherein the dielectric barrier discharge excimer lamp has a filling gas of 50 mbar to 600 mbar.   The dielectric barrier discharge excimer lamp is based on 0 wt% to 100 wt% argon and / or 0 wt% to 100 wt% krypton and / or 0 wt% based on the total weight of the filling gas therein. 5. A device according to claims 1 to 4, comprising from wt% to 100wt% xenon. The dielectric barrier discharge excimer lamp comprises a phosphor material, which is preferably YPO ₄ : Nd, YPO ₄ : Bi, YPO ₄ : Pr, LuPO ₄ : Pr, and / or LaPO _4. 6. The device according to claims 1 to 5, which is selected from: Pr, more preferably a mixture thereof.   The dielectric barrier discharge excimer lamp is 150 nm to 200 nm, preferably 160 nm to 190 nm, more preferably 170 nm to 180 nm, 160 nm to 230 nm, preferably 170 nm to 210 nm, more preferably 175 nm to 190 nm, or 220 nm. Device according to claims 1 to 6, having a maximum emission luminance at a wavelength between ˜250 nm, preferably 225 nm to 249 nm, more preferably 230 nm to 248 nm.   8. An apparatus according to any preceding claim, wherein the dielectric barrier discharge excimer lamp is pulsed.   9. An apparatus according to claim 1 having a combustion chamber, the combustion chamber having a pre-combustion gas flow to the combustion chamber and a post-combustion gas flow of exhaust from the combustion chamber, An apparatus in which one dielectric barrier discharge excimer lamp is located in the pre-combustion gas stream.   For treating the fluid to reduce the concentration of at least one contaminant in the fluid, preferably to reduce the concentration of at least one contaminant in the gas stream, more preferably at least one of the fluids of the fuel cell. Use of the device according to claims 1 to 9 for treating the exhaust gas stream from the combustion of the engine so as to reduce the concentration of one pollutant.

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