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WO2016112943A1 - Ozoniseur, convertisseur no/no2, procédé de conversion de no en no2 et utilisation associée - Google Patents

Ozoniseur, convertisseur no/no2, procédé de conversion de no en no2 et utilisation associée Download PDF

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Publication number
WO2016112943A1
WO2016112943A1 PCT/EP2015/002536 EP2015002536W WO2016112943A1 WO 2016112943 A1 WO2016112943 A1 WO 2016112943A1 EP 2015002536 W EP2015002536 W EP 2015002536W WO 2016112943 A1 WO2016112943 A1 WO 2016112943A1
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WO
WIPO (PCT)
Prior art keywords
ozone
air
ozone generator
unit
nitrogen
Prior art date
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PCT/EP2015/002536
Other languages
German (de)
English (en)
Inventor
Denis Pöhler
Martin Horbanski
Ulrich Platt
Original Assignee
Universität Heidelberg
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Filing date
Publication date
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Publication of WO2016112943A1 publication Critical patent/WO2016112943A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
    • C01B13/10—Preparation of ozone
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
    • C01B21/36—Nitrogen dioxide (NO2, N2O4)
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0011—Sample conditioning
    • G01N33/0013—Sample conditioning by a chemical reaction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
    • B01D2253/10—Inorganic adsorbents
    • B01D2253/106—Silica or silicates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/54—Nitrogen compounds
    • B01D53/56—Nitrogen oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/54—Nitrogen compounds
    • B01D53/56—Nitrogen oxides
    • B01D53/565—Nitrogen oxides by treating the gases with solids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
    • G01N33/0037—NOx
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Definitions

  • the invention relates to an ozone generator, a NO to N02 converter with the ozone generator, a method for converting NO to NO2 and a use of the ozone generator and the NO to N02 converter.
  • the quality and composition of the air in our atmosphere is of particular importance to humans, as low concentrations of pollutants can already have a significant impact on health and the environment.
  • nitrogen oxides NO x ie NO and / or NO 2.
  • the measurement of NO x also plays an important role in science and is therefore widespread.
  • such measurements are used in the industry in emissions but also in manufacturing processes and have also found wide application in medicine.
  • DOAS differential optical absorption spectroscopy
  • the DOAS is described, for example, in Platt et al .: "Simultaneous measurements of atmospheric CH20, 03 and NO2 by differential optical absorption", J. Geophys. Res., 1979, 84, 6329-6335.
  • the DOAS allows a direct and non-contact measurement of gases, especially NO2, in the atmosphere and is a very established and successful measurement method for atmospheric trace substances, especially in science. DOAS uses the characteristic wavelength-dependent absorption of light by molecules to quantitatively measure their concentration. It is exploited that the absorption spectrum of a substance represents a clear fingerprint.
  • BB-CEAS broadband cavity enhanced absorption spectroscopy
  • NO nitrogen monoxide
  • the ozone production rate or the ozone concentration is too low to cause, on the one hand, rapid and complete conversion of NO to NO 2 and, on the other hand, to minimize the dilution of the measurement air.
  • the O3 mixing ratio in the measuring air is 1 ppm
  • the 03 generator must produce air with more than 10ppm O3 to get by with an air admixture of less than 10%. If a lower ozone concentration were used for the NO measurement, the necessary higher ozone addition would dilute the measuring air more strongly and thus reduce the measuring accuracy.
  • a longer reaction time for the conversion or conversion of NO to NO 2 would be necessary until a maximum conversion occurs, which then turns out to be somewhat lower.
  • a longer reaction time also has the disadvantages of a large reaction volume and a time delay of the measurement. Since commercial ozone generators do not achieve sufficiently high ozone concentrations when operating with ambient air and because they greatly distort the measurement result by the generated nitrogen oxides, they can not readily for NO measurement by conversion with the ozone to NO2 and subsequent measurement by means of DOAS or other methods are used.
  • the invention provides a suitable ozone generator which can be operated with ambient air and generates an ozone-containing air largely free of NOx.
  • the invention provides a NO to N02 converter that allows for indirect measurement of nitrogen monoxide content using a N02 meter, such as a DOAS instrument.
  • the invention provides a related method and a use thereof.
  • a first independent aspect for achieving the object relates to an ozone generator for generating ozone from ambient air, comprising:
  • an ozone generating unit for generating ozone from the ambient air
  • an oxidation unit for oxidizing nitrogen monoxide produced in the ozone generating unit to higher nitrogen oxides
  • a post-filtering unit for at least partially or almost completely filtering out the higher nitrogen oxides produced in the oxidation unit.
  • the ozone generator may further include a pump for sucking the ambient air.
  • the ozone generating unit can then generate ozone from the intake ambient air.
  • the ozone generating unit can, for example, by means of photolysis, convert at least some of the oxygen contained in the ambient air into ozone.
  • the ozone generating unit may have, for example, a mercury vapor lamp.
  • the oxidation unit may comprise a reaction zone or a reaction volume.
  • the NO produced in the ozone generating unit in particular by a reaction of excited oxygen with nitrous oxide, can successively react with the ozone to produce higher nitrogen oxides such as NO 2, NO 3 and / or N 2 O 5.
  • the ozone-containing air generated by the ozone generator is advantageously substantially free of nitrogen oxides, ie not contaminated with nitrogen oxides, although the ozone generator is operated only with ambient air.
  • the contamination of NO (and other NOx) can thus be significantly reduced. Consequently, the ozone generator according to the invention, in comparison to conventional ozone generators operated with ambient air, is suitable for an indirect measurement of the NO content with the aid of an NO 2 measuring device.
  • the post-filtration unit comprises a post-filter or a post-filter cartridge or a reaction volume with silica gel.
  • Silica gel filters out or absorbs the higher nitrogen oxides such as NO2, NO3 and N2O5. Although the silica gel also absorbs ozone, but achieves saturation after a few hours. After that, ozone can pass the silica gel without any losses.
  • the postfiltering unit may preferably comprise an aerosol postfilter. This advantageously prevents particles from escaping from the silica gel.
  • the ozone generator furthermore has a prefiltration unit for removing reactive compounds or substances from the ambient air, in particular from the intake ambient air.
  • the prefiltration unit advantageously ensures that the introduction of nitrogen oxides into the ozone generator is avoided. Thereby, the generation of undesirable substances such as NO2 in the ozone generator or the ozone generating unit of the ozone generator can be reduced by the Prefilter unit removes reactive substances or compounds from the air.
  • the prefiltration unit at least partially filters out nitrogen dioxide from the ambient air and / or prevents the penetration of particles.
  • the prefilter unit comprises a filter with activated carbon. This can be used to remove numerous reactive substances.
  • the prefilter unit comprises a filter with silica gel.
  • the silica gel filter is used to filter NO2, NO3 and N2O5.
  • the silica gel filter also dries the air.
  • the prefilter unit comprises an aerosol filter, i. a membrane filter or a depth filter.
  • the aerosol filter prevents the penetration of particles into the ozone generator or into the ozone generating unit of the ozone generator.
  • the aerosol filter may e.g. Teflon or partially or completely formed of Teflon.
  • the pore size of the aerosol filter is less than or equal to 5 ⁇ to filter out even correspondingly small aerosols.
  • a filter can generally comprise or be a filter cartridge and / or a reaction volume.
  • the ozone generating unit comprises an airtight container with an air inlet to the inlet of air, in particular from the Vorfilterungsaku, and an air outlet to the outlet of ozone-enriched air, wherein in the airtight container, a UV lamp for emitting of UV radiation for a photolysis of oxygen molecules is arranged such that the UV lamp is flowed around by the air entering the container, in particular in direct or direct contact.
  • the airtight container of the ozone generating unit is preferably an airtight tube.
  • the length of the container or tube is preferably in the range of 5 to 30 mm and the diameter of the container or tube is preferably in the range of 15 to 25 mm.
  • the UV lamp is preferably a luminous tube, which is arranged along a longitudinal axis of the container or tube, in particular collinear to the tube, so that the air entering or entering the container is guided around the UV lamp close and completely enclosing.
  • the ultraviolet lamp can emit ultraviolet (UV) radiation, ie, short wavelength radiation, which is capable of causing photolysis of oxygen molecules analogously to ozone generation in the stratosphere.
  • the UV lamp may have, for example, a wavelength range of about 180 to 242 nm.
  • the UV lamp is a mercury vapor lamp (Hg lamp).
  • Hg lamp the 184.9 nm emission line can be used to photolyze oxygen, ie the conversion of oxygen to ozone by shortwave UV light.
  • the air inlet and the vent outlet of the container are preferably offset from one another on opposite sides of the container and along a longitudinal direction of the container or a longitudinal direction of the UV lamp.
  • the air inlet at a first axial end of the container or the UV lamp and the air outlet at a second axial end of the container or the UV lamp is arranged.
  • the UV lamp is disposed between the air inlet and the air outlet. This ensures that the ambient air passing through the container is irradiated as effectively as possible by the UV lamp.
  • the air inlet and / or the air outlet may comprise a controllable valve with which the air flow flowing into the ozone generating unit and / or the air flow flowing out of the ozone generating unit can be regulated.
  • the air outlet Through the air outlet, the ozone-enriched air can flow out of the ozone generating unit and enter or flow into the oxidation unit.
  • the arrangement of the UV lamp in the interior of the container, ie in direct or direct contact with the air flowing into the container, the ozone generator according to the invention or the ozone generating unit advantageously has a compared to conventional ozone generators, for example compared to Ozone generators with an arranged next to or outside of quartz glass tubes mercury vapor lamp, higher ozone production or ozone production rate.
  • the above-described ozone generating unit regardless of the oxidation unit and / or the Nachfilterungsussi, compared to conventional ozone generators or ozone generating units advantageous properties. Therefore, the ozone generating unit may also constitute an independent aspect of this description.
  • an inner wall of the container comprises a material or an inner wall of the container is formed partially or completely of a material which has a reflectivity for the ultraviolet radiation emitted by the UV lamp and suitable for photolysis of at least 0, 1 has.
  • the UV radiation reflective material on the inner wall of the container may also have a reflectivity of at least 0.2, preferably at least 0.4, more preferably at least 0.5, and most preferably of at least 0.75.
  • an inner surface i. a surface or surface facing the interior of the container.
  • the inner wall or inner surface of the container faces the UV lamp arranged in the container.
  • UV radiation is a radiation having a wavelength which is suitable to split oxygen molecules and thus leads to the formation of ozone upon irradiation of oxygen-enriched air.
  • light with a wavelength of less than 242 nm is suitable for the photolysis of oxygen molecules.
  • the light of a mercury vapor lamp having a wavelength of 184.9 nm is suitable for photolysis.
  • the ozone generator according to the invention advantageously a much higher efficiency of ozone generation compared to conventional ozone generators, for example ozone generators with a mercury vapor lamp, which is arranged next to or outside of quartz glass tubes .
  • ozone generators with a mercury vapor lamp which is arranged next to or outside of quartz glass tubes .
  • quartz glass tubes In the usual quartz glass tubes, only a very small part of the emitted mercury vapor lamp light is used to illuminate the oxygen-containing air in the quartz glass tube. This results in a much lower efficiency.
  • even small UV lamps e.g. Hg lamps with a length of 9 cm, to a saturation ozone concentration of over 350ppm with an air flow of less than 0.1 l / min.
  • the UV lamp is a mercury vapor lamp.
  • the 184.9 nm emission line of the mercury vapor lamp can be used for the photolysis of oxygen molecules and thus for ozone generation.
  • the airtight container or the airtight tube on the inner wall of the container aluminum is formed of aluminum.
  • the reflectance of aluminum is particularly high for UV radiation.
  • the reflectivity of pure aluminum for the 184.9 nm emission line is about 0.8. Due to the additional reflections generated in the ozone generating unit, the efficiency of the ozone generator can be increased.
  • the ozone generator according to the invention further comprises a flow controller for setting or controlling the air flow through the ozone generating unit.
  • the flow regulator is preferably a controllable valve with a flow meter.
  • the flow regulator is arranged between the prefiltration unit and the ozone generating unit of the ozone generator. With the air flow also the residence time of the air in the ozone generator or in the ozone generating unit is adjusted.
  • the flow controller is configured such that the residence time of the air in the ozone generating unit is less than a photolysis equilibrium time.
  • the flow regulator is configured or the air flow adjusted so that the residence time of the air in the ozone generating unit is less than 99% of the photolysis equilibrium time.
  • the photolysis equilibration time is understood to be the time from which the ozone production rate and the ozone destruction rate for the air contained in the ozone generating unit are substantially equal. From the photolysis equilibration time, the ozone concentration no longer increases, i. the system is in photolytic equilibrium. In other words, the photolysis equilibration time is that time necessary to reach the maximum possible ozone concentration. It is a characteristic of the ozone generator and can e.g. be determined experimentally.
  • the residence time greater than or equal to the photolysis equilibrium time.
  • some undesirable substances especially N 2 O (nitrous oxide)
  • N 2 O nitrogen oxide
  • the N 2 O content in the air is about 317 ppm.
  • N2O in the ozone generator is converted to NO via excited oxygen and then successively into NO2, NO3 and N2O5. This can lead to a disturbing N02 contamination of the measuring air and thus to measurement errors.
  • a typical Admixture of 1% - 0% of ozonated air to the measurement air may result in more than 10ppb of NC contamination.
  • the residence time of the air in the ozone generating unit is less than the photolysis equilibration time, the N2O conversion in relation to the O3 production can be kept as low as possible.
  • the undesired formation of NO, and successive NO 2, in the ozone generator can be kept as low as possible or reduced in this way. If the air remained in the ozone generating unit for as long or longer than the photolysis equilibrium time, the N2O conversion would continue while the O3 concentration did not increase further.
  • a further independent aspect for achieving the object relates to a nitrogen monoxide-to-nitrogen dioxide converter (NO-to-N02 converter) for the indirect measurement of the nitrogen monoxide content of measuring air with the aid of a nitrogen dioxide measuring device, in particular with the aid of a DOAS or CE-DOAS -Instrumentes.
  • the NO-to-NO 2 converter comprises an ozone generator according to the invention for generating ozone and a reaction unit for converting at least part of the nitrogen monoxide contained in the measurement air into nitrogen dioxide by means of the ozone generated by the ozone generator.
  • the reaction unit is preferably a reaction volume in which the measurement air is combined or mixed with the ozone generated by the ozone generator.
  • the nitrogen monoxide contained in the measuring air reacts in this reaction unit with the ozone to form nitrogen dioxide and oxygen:
  • the NO2 mixing ratio of the measurement air is then composed of the atmospheric NO 2 concentration and the concentration of the converted NO:
  • the atmospheric N0 2 content can be determined by a measurement without O3 addition.
  • the NO 2 content can be measured with Cb addition.
  • the reaction unit comprises a container through which the measurement air can flow, the volume of the container having a size such that the measurement air and the ozone generated by the ozone generator remain there for so long until the conversion of nitrogen monoxide contained in the measuring air to nitrogen dioxide has taken place substantially completely
  • the container is preferably inert, i. it is designed so that it does not participate in certain chemical processes, in particular reactions with NO2.
  • the container may consist entirely or partially of glass or Teflon.
  • the container may e.g. be a hose.
  • the volume of the tube and thus the duration of the measurement air in the tube can be set or determined.
  • substantially complete it is meant in the sense of this specification that the conversion of the nitrogen monoxide contained in the measurement air to nitrogen dioxide has occurred at least 50%, preferably at least 90% and most preferably at least 95%.
  • too long a residence time is also undesirable since NO2 can then oxidize to higher oxides.
  • the optimal volume of the container or the optimal residence time of the measuring air in the container depends on the respective concentrations.
  • the volume of the container is such that the residence time of the measurement air in the container or in the reaction unit is about 5 to 15 seconds.
  • Another independent aspect for achieving the object relates to a method for converting nitrogen monoxide contained in measuring air to nitrogen dioxide for indirect measurement of the nitrogen monoxide content of the measuring air with the aid of a NO2 measuring instrument, in particular with the aid of a DOAS or CE-DOAS instrument.
  • the method comprises the steps:
  • the measurement air and the ozone are left in the reaction unit until the conversion of the nitrogen monoxide contained in the measurement air into nitrogen dioxide has essentially taken place completely.
  • the production of ozone by means of the ozone generator comprises adjusting the air flow through the ozone generator, in particular by means of a flow regulator, so that the residence time of the air in the ozone generator or in the ozone generating unit is less than a photolysis equilibrium time.
  • the method may further comprise one or more of the following steps:
  • Determining or determining or calculating the nitrogen monoxide content of the measurement air by comparing the measured nitrogen dioxide content of the converted measurement air with a reference measured value.
  • the reference measurement results from a reference measurement, wherein the reference measurement is a measurement of the nitrogen dioxide content of the pure measurement air, ie the measurement air without adding ozone.
  • the reference measurement is one Measurement of the measuring air without using the NO-to-N02 converter or ozone generator.
  • the mixing ratio of the converted nitrogen monoxide can be determined. This mixing ratio essentially corresponds to the mixing ratio of nitrogen monoxide in the measuring air, ie the nitrogen monoxide content of the measuring air, divided by the conversion factor typical for the measuring instrument. Since the conversion factor is ideally close to 1, it can be neglected.
  • the NO content of the measurement air can also be measured indirectly by means of an NO 2 measuring device, in particular by means of DOAS or CE-DOAS.
  • a further independent aspect for achieving the object relates to a use of the ozone generator according to the invention for the indirect measurement of the nitrogen monoxide content of measuring air with the aid of a nitrogen dioxide measuring device, in particular with the aid of a DOAS or CE-DOAS or with the aid of a DOAS or CE-DOAS measuring device ,
  • a further independent aspect for achieving the object relates to a use of the nitrogen monoxide to nitrogen dioxide converter according to the invention for the indirect measurement of the nitrogen monoxide content of measuring air with the aid of a nitrogen dioxide measuring device, in particular with the aid of a DOAS or CE-DOAS or with the aid of a DOAS or CE-DOAS measuring device.
  • Figure 1 shows a schematic drawing of an ozone generator according to a preferred embodiment
  • Figure 2 shows a schematic drawing of an ozone generating unit of the ozone generator according to the invention according to a preferred embodiment
  • FIG. 3 shows a schematic representation of the conversion of N 2 O in a photolytic ozone generator
  • Figure 4 shows a schematic flow diagram for an ozone generator according to a preferred embodiment
  • Figure 5 shows a schematic drawing of a NO to N02 converter according to a preferred embodiment with a downstream DOAS or BB-CEAS measurement;
  • FIG. 6 shows a simulated time profile of the ratio of
  • NO 2 to NO x (NO + NO 2 ) in an NO to NO 2 converter according to the invention with an admixed ozone concentration of 1.5 ppm at the beginning of the NO to NO 2 core version (t 0) for different NO starting concentrations NO initial concentration also corresponds to the initial concentration of NO2.
  • location. B. top, bottom, side, etc. are each related to the immediately described and illustrated figure and are mutatis mutandis to transfer to a new position to the new situation.
  • FIG. 1 shows a schematic drawing of an ozone generator 100 according to a preferred embodiment.
  • the ozone generator 100 includes a pump 3 for sucking in ambient air 1, a pre-filtering unit 10 for pre-filtering the ambient air, a flow controller 13 for adjusting the air flow, an ozone generating unit 15 for generating ozone-containing air 50, an oxidation unit 30, and a post-filtering unit 40.
  • the individual components are each connected to each other by means of a supply line or gas line 6.
  • the ozone generator. 100 the prefilter system 0 from an activated carbon filter 5, a silica gel filter 7 and a particulate filter 9, which removes reactive compounds from the air.
  • the activated carbon filter 5 removes many reactive substances.
  • Silica gel filter 7 filters out nitrogen oxides such as NO2, NO3 and N2O5.
  • the Aeorosol filter 9 acts as a membrane filter or depth filter the penetration of particles into the ozone generator 100 or in the ozone generating unit 15 or prevents penetration of particles into the ozone generator 100 and in the ozone generating unit 15th
  • the flow regulator 13 comprises a controllable valve 11 and a flow meter 12. Based on the flow of the air measured by the flow meter 12, the valve 11 can be opened or closed further to adjust the air flow to a predetermined value.
  • the ozone generating unit 15 comprises an airtight container or an airtight tube 17, wherein the container or the tube 17 is preferably formed wholly or partly of aluminum.
  • a UV lamp 25 preferably a mercury vapor lamp is arranged, which is fastened by means of a lamp holder 27 on the container 17.
  • An opening of the container or tube 17 is mounted, i. in operational or operational condition, with a cap 19 hermetically sealed or sealed.
  • the closure cap 19 must be sufficiently inert and is thus preferably made of Teflon. It is understood that a construction without cap 19 is possible.
  • an aluminum rod in which a cavity is drilled or rotated from one side or an aluminum-coated glass body may be used.
  • the ozone generating unit 15 or the container 17 also has an air inlet or an air inlet opening 21 for receiving the pre-filtered by the Vorfilterungsaku 10 ambient air 1 and an air outlet or an air outlet opening 23 to the outlet of the ozone-enriched air 50.
  • a compression fitting 26, 28 may be provided, which seals against the lamp holder 27.
  • the ozone generator 100 is operated with ambient air 1 and therefore does not require any consumption gases, ie there is no need for an oxygen gas cylinder, which must be connected to the ozone generator. This means a large cost saving and at the same time is an important advantage for the operation since the use of oxygen cylinders is often due to safety regulations is critical.
  • the ozone generator 100 is based, analogous to 0 3 generation in the stratosphere, on the photolysis of oxygen molecules by short-wave UV radiation.
  • the 184.9 nm emission line of a mercury vapor lamp 25 is used for this purpose.
  • the mercury vapor lamp 25 is for this purpose in an air-tight aluminum tube 17, which has a defined air inlet 21 and a defined air outlet 23 installed.
  • a high efficiency ie a high ozone generation rate or a high ozone concentration, it has been found that the material of the container or tube 17 is crucial.
  • the container in particular the inner wall of the container, a material with a high reflectivity with respect to that of the UV lamp 25 to Having photolysis emitted radiation.
  • aluminum is the material for the container 17.
  • the container or the tube 17 may be made entirely of aluminum or only partially.
  • only the inner wall of the container or tube 17 may be completely or partially coated with aluminum.
  • the UV or Hg lamp 25 is arranged in the container 17 such that the air is passed around the mercury vapor lamp 25 closely and completely enclosing. In combination with the additional reflections on the aluminum, a significantly higher efficiency of ozone production compared to comparable ozone generators is achieved with a mercury vapor lamp.
  • the ozone production in the ozone generator 100 is limited by the photolysis of 0 3 .
  • the main contributor to this is the emission line of the Hg lamp at 253.6 nm, which accounts for almost 100% of the lamp intensity. If air enters the ozone generator, then initially the ozone production rate is greater than the rate of ozone depletion and the ozone concentration increases. However, as the ozone concentration increases, the ozone depletion rate increases until it is as high as the ozone production rate. From this equilibrium time, the so-called photolysis equilibrium time t gg , increases Ozone concentration is no longer on, the system is from this point in the photolytic equilibrium.
  • the equilibrium concentration of ozone for a typical Pen-Ray mercury vapor lamp (with an intensity ratio of 184.9 nm and 253.6 nm emission lines of about 300ppm.
  • a maximum ozone yield it makes sense in principle to set the residence time of the prefiltered ambient air 1 in the ozone generating unit 15 to at least the equilibrium time t gg , ie the time until the maximum possible ozone concentration is reached.
  • the equilibrium time t gg can be determined by characterizing the ozone generator 100 by measuring the ozone concentration obtained as a function of the air flow. If the plateau of the maximum achievable ozone concentration of about 300ppm to 370ppm is reached with a reduction of the flow, the equilibrium time t gg is reached.
  • the equilibrium time t gg can also be increased by a smaller mercury vapor lamp or a lower lamp voltage.
  • FIG. 2 shows a schematic drawing of an ozone generating unit 15 of the ozone generator 100 according to the invention according to a preferred embodiment.
  • the air-tight container 17, the UV lamp 25 connected to an electrical cable 29, the lamp holder 27 and the closure cap 19 are also shown in FIG.
  • the air inlet 21 and the air outlet 23 are located on opposite sides of the container 17 and are also offset from one another in an axial direction of the container 17.
  • the air inlet 21 is at a first axial end 17a of the container 17 or the UV lamp 25, while the air outlet 23 is arranged at a second axial end 17b of the container 17 or the UV lamp 25.
  • the UV lamp 25 is thus arranged between the air inlet 21 and the air outlet 23.
  • a flange 26 and a seal or a clamping ring 28, which is preferably formed of Teflon, for fastening and sealing of the UV lamp 25 inserted into the container 17 are also shown in FIG.
  • the flange 26 and clamping ring 28 in particular form a compression fitting.
  • the UV lamp 25 is designed as a light tube and arranged in the container or tube 17 such that a longitudinal axis of the arc tube is aligned parallel to a longitudinal axis of the container or tube 17.
  • the UV lamp 25 extends substantially through the entire container or through the entire tube 17th
  • ozone generator 100 of the present invention With the ozone generator 100 of the present invention and the ozone generating unit 15, it is possible to increase the ozone production rate by more than a factor of ten as compared with conventional ozone generators using Hg lamps.
  • N 2 O (laughing gas) in an ozone generator or an ozone generating unit via excited oxygen, ie 0 ( 1 D) from the 03 photolysis at 253.5 nm, in NO and then successively converted into NO2, NO3 and N2O5.
  • excited oxygen ie 0 ( 1 D) from the 03 photolysis at 253.5 nm
  • NO2, NO3 and N2O5 For a typical admixture of 1% to 10% of ozonized air to the ambient air or measurement air, such reactions may result in an N02 contamination of more than 0ppb. Since such an impurity can lead to a considerable measurement error in an indirect NO measurement, the ozone generator 100 still has an oxidation unit or a reaction volume 30 and a post-filtering unit 40 (see FIG. 1).
  • the NO produced from excited oxygen and nitrous oxide in the ozone generating unit 15 can thus be minimized.
  • the oxidation unit 30 at least part of the nitrogen monoxide produced by excited oxygen and nitrous oxide in the ozone generating unit 15 is oxidized to higher oxides such as NO 2, NO 3, N 2 O 5 (NO reacts very rapidly with the ozone, ie successively in less than about 2 seconds) higher oxides like
  • the post-filtering unit 40 has a filter 42 with silica gel.
  • the silica gel absorbs NO2 as well as NO3 and N2O5, but ozone can pass well. Although the silica gel also absorbs ozone, but reaches saturation after a few hours, i. E. it is in ozone saturation. In this saturated state of the silica gel, ozone can pass the silica gel without loss. In addition to or instead of silica gel, other NOx filters can be used.
  • the post-filtering unit 40 also has an aerosol filter 44. The aerosol filter 44 reduces or prevents the escape of particles from the silica gel.
  • the contamination of the ozone-containing air generated by the ozone generating unit 15 can be significantly reduced with NO and NO x, respectively, so that by means of the ozone generator 100 according to the invention an indirect NO measurement, e.g. with the help of a DOAS measuring device.
  • the NO of the measuring air with the ozone to NO2 must be converted with the aid of a NO-to-N02 converter (see FIG. 5).
  • the residence time of the air in the ozone generator 100 or in the ozone generating unit 15 falls below the equilibrium time t gg .
  • a corresponding adaptation can take place on the one hand by the adaptation of the power of the ozone generator 100 or of the ozone generating unit 15 and on the other hand by the variation of the air flow. For longer residence times, the N2O conversion will continue while the 03 concentration does not increase further.
  • the undesired formation of NO, and successive NO 2 in the ozone generator 100 or in the ozone generating unit 15 can be reduced to such an extent that the NO produced by the ozone generator 100 has a concentration which is below the measurement accuracy for NO of the DOAS measuring device lies.
  • the nitrogen oxide entry from the ozone generator 100 is ⁇ 10 Oppt below the detection limit.
  • FIG. 4 shows a schematic flow diagram for an ozone generator 100 according to a preferred embodiment. As illustrated in the diagram of FIG. 4, the following processes or method steps take place in the ozone generator 100 for producing ozone:
  • Membrane filter or depth filter 9 for reducing or preventing the ingress of particles, in particular in the ozone generating unit 30 of the ozone generator 100;
  • FIG. 5 shows a schematic drawing of a NO-to-NO 2 converter 200 according to a preferred embodiment with a downstream DOAS or BB-CEAS measurement.
  • the NO-to-NO 2 converter 200 comprises an ozone generator 100 according to the invention which is capable of producing a sufficiently high ozone concentration with a negligible NO x impurity, and a reaction unit 130 in which the air to be measured, i. the measurement air whose NO content is to be measured, and the ozone-containing air of the ozone generator 100 are merged or mixed or mixed.
  • this may e.g. be realized in a simple manner by means of supply lines 110 which are connected via a coupling element 115.
  • ⁇ 03 denotes the flow of the ozone or the ozone-containing air generated by the ozone generator 100, ⁇ the flow of the measurement air, and ⁇ the flow through an N02 or DOAS measuring device 150.
  • the reaction unit 130 comprises a reaction volume.
  • the reaction volume is an inert container or simply a long tube, which ensures that the air mass is in the reaction unit 130 long enough before being fed into the DOAS measuring system 150, so that the necessary reaction NO + O 3 -> NO 2 as completely as possible.
  • the residence time of the measurement air or the ozone-containing air in the reaction unit 130 can be easily varied and adjusted by the length of the tube.
  • the reaction unit 130 or the reaction volume is adapted to the air flow and to the volume of the DOAS measuring cell.
  • the reaction volume VR is as follows:
  • VDOAS is the volume of the DOAS measuring cell and F is the volume flow of the air.
  • the optimum reaction time To P t: No-> N02 is calculated so that the maximum conversion in the middle of the measuring cell is achieved. This ensures that only minimal losses occur in the measuring cell. If the reaction volume is, for example, a tube with an inside diameter of 4 mm, the reaction volume calculated above corresponds to a length of the tube of 2 m.
  • N0 2 + 0 3 - »N0 3 + 0 2 N0 2 + N0 3 + M -> N 2 0 5 + M is relatively low and, depending on the NO and NO 2 concentration, a conversion of at least 90% up to 98% can be achieved.
  • M represents another collision partner which is necessary for reasons of energy conservation.
  • Figure 6 shows a simulated time course of the ratio of NO 2 to NO x (i.e., NO and NO 2) in an NO to NO 2 converter according to the present invention.
  • curves for different NO initial concentrations [NO] are plotted, the NO initial concentration also corresponding to the initial concentration of NO 2. It can be seen that NO is rapidly converted to NO 2 by the high ozone concentration for all curves shown.
  • the time with the highest degree of conversion varies only very slightly from the NO initial concentration.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
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  • Life Sciences & Earth Sciences (AREA)
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  • Food Science & Technology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Investigating Or Analysing Materials By The Use Of Chemical Reactions (AREA)
  • Oxygen, Ozone, And Oxides In General (AREA)
  • Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)

Abstract

L'invention concerne un ozoniseur (100) servant à produire de l'ozone à partir de l'air ambiant (1), un convertisseur NO/NO2 (200) comprenant cet ozoniseur (100), un procédé de conversion de NO en NO2 et l'utilisation de cet ozoniseur (100) et de ce convertisseur NO/NO2 (200). L'ozoniseur (100) présente : une unité de génération d'ozone (15) servant à produire de l'ozone à partir de l'air ambiant ; une unité d'oxydation (30) servant à oxyder le monoxyde d'azote formé dans l'unité de génération d'ozone (15) en oxydes d'azote supérieurs ; et une unité de filtration secondaire (40) servant à filtrer au moins partiellement les oxydes d'azote supérieurs produits dans l'unité d'oxydation (30).
PCT/EP2015/002536 2015-01-14 2015-12-16 Ozoniseur, convertisseur no/no2, procédé de conversion de no en no2 et utilisation associée WO2016112943A1 (fr)

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DE102015000423.9A DE102015000423A1 (de) 2015-01-14 2015-01-14 Ozongenerator, NO-zu-NO₂-Konverter, Verfahren zum Konvertieren von NO zu NO₂ und Verwendung

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CN106693692A (zh) * 2016-12-16 2017-05-24 余姚保世洁环保设备有限公司 一种工业废气光氧催化装置
CN109748244A (zh) * 2019-02-01 2019-05-14 北京雪迪龙科技股份有限公司 一种低浓度臭氧发生装置及制备低浓度臭氧的方法
EP3553499A1 (fr) 2018-04-13 2019-10-16 Siemens Aktiengesellschaft Analyseur de gaz et procédé de mesure des oxydes d'azote dans un gaz d'échappement

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CN106693692A (zh) * 2016-12-16 2017-05-24 余姚保世洁环保设备有限公司 一种工业废气光氧催化装置
CN106693692B (zh) * 2016-12-16 2019-03-12 余姚保世洁环保设备有限公司 一种工业废气光氧催化装置
EP3553499A1 (fr) 2018-04-13 2019-10-16 Siemens Aktiengesellschaft Analyseur de gaz et procédé de mesure des oxydes d'azote dans un gaz d'échappement
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CN109748244A (zh) * 2019-02-01 2019-05-14 北京雪迪龙科技股份有限公司 一种低浓度臭氧发生装置及制备低浓度臭氧的方法

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