DE10236717B4 - Apparatus for carrying out photoreactive processes in a fluid - Google Patents

Abstract

contraption to carry out of photoreactive processes in a fluid that is along predeterminable flow paths traverses at least one reaction chamber (10), which can be evacuated and / or is provided with a reactive gas and the at least an energy entry means (14) whose field is a discharge generated, the emitted radiation, the fluid at least over a Part of its way in the reaction chamber (10) influenced, wherein the energy input means (14) at least two electrodes (16, 18) wherein the reaction chamber (10) at least partially from a cylindrical electrode (16) and at least a counter electrode (18) disposed within the reaction chamber (10) and is electrically isolated from the cylindrical electrode (16), characterized in that the fluid within the reaction chamber (10) is guided in tubes (32) made of radiation-permeable material.

Description

The The invention relates to a device for carrying out photoreactive processes in a fluid having the features of the preamble of claim 1.

The The invention thus relates to a device for carrying out photoreactive processes in a fluid, resulting in a photochemical induced degradation of particular organic compounds, particles and microorganisms. Upon photochemical excitation, molecules become one through light absorption defined amount of energy supplied directly. In fluids, such as solutions and gas mixtures may be a compound dissolved in low concentration in the presence of a large surplus non-absorbent solvents or carrier gas and also in the presence of other non-absorbing compounds in the excitation energy be stimulated. Photochemical reactions therefore often have the Advantage of high selectivity.

The Generation of ultraviolet rays is by means of thermal radiators, Gas discharge lamps, arc lamps and lasers possible for different purposes Applications are also used. Commercially available equipment for the Photochemistry is mainly offered with gas discharge lamps. For high Quantum yields are dependent on the type of gas, doping and modify gas pressure in their radiation yield and thus for certain adjust photochemical effects. The photochemical effect of Ultraviolet radiation is well studied and in the literature relevant documented. A comprehensive overview offers Jürgen among others Kiefer in his standard work "Ultraviolet Rays "(de Gruyter, Berlin 1977 ISBN 3-11-001641-9) and a detailed spectra collection is published in UV Atlas by Butterworth Verlag Chemie.

Known Reactor constructions as freely available on the market, point frequently Small-lumen radiation sources, usually in the form of individual gas discharge lamps on, which then emanating from the very small thread or even punctiform sources radiation fluxes on big exchange surfaces have to be distributed such as. in a trickle-film reactor, still considered one of the cheaper ones geometric constellations for the energy transfer can be considered. Another disadvantage of the small-lumen lamps is the very limited lifetime due to their high energy densities. The enlargement of the Energy transition surfaces is technically through whole bundles (arrays) of radiation sources replaced (see, for example, US Patent 5,601,184 and PCT WO 95/28181).

Photochemical Degradation reactions (photo-degradation) are often not single-stage and can already This makes it irreversible that subsequent reactions of the primary products occur. The latter can be achieved by an appropriate spectral composition the UV radiation favors even further become. additionally are degradation processes of organic substances in the presence of oxygen and oxygen-releasing compounds very much accelerated. Except hydrogen peroxide and ozone are a whole range of reactive oxygenated Radical and metastable oxygen compounds described and their effect on processes used (see Photochemical Processes for Water Treatment, O. Legrine et al. Chem. Rev 1993 93, 671-698).

• 1. hohe Quantenausbeuten der Strahlung,
• 2. durch geeignete Reaktorgeometrie die Energie-Übergangsfläche zu erhöhen,
• 3. durch die Prozeßführung mit Reaktanden die Rückreaktion zu beeinträchtigen,
• 4. durch Katalysatoren die Reaktionsgeschwindigkeiten zu erhöhen und
• 5. durch Synergie-Effekte von UV- und NIR-Strahlung bei Sterilisationsprozessen mikrobielle Reparaturvorgänge zu beeinträchtigen.

For reasons of economy, therefore, the aim in all known methods and devices is:

• 1. high quantum yields of the radiation,
• 2. increase the energy transfer surface by suitable reactor geometry,
• 3. interfere with the reaction by reacting with reactants,
• 4. by catalysts to increase the reaction rates and
• 5. Affects microbial repair processes through synergy effects of UV and NIR radiation during sterilization processes.

By the DE 195 00 802 A1 is an irradiation device in the form of a tubular reactor for generating photochemical reactions in media known, in particular in aqueous or aqueous fluids, with at least one, an electrical gas discharge in a reaction chamber generating photochemical radiation source whose radiation passing in at least one tube liquid in the range of action of the irradiation source interspersed and to increase the efficiency of the radiation utilization in the known device, it is proposed that the tube each leading the liquid is disposed within the reaction chamber or the discharge space of the photochemical radiation source.

Although it has been proposed in the known solution to improve the performance within the reaction chamber to provide additional electrodes for uniform distribution and / or stabilization of the gas discharge, the results obtained in this way are not satisfactory, so that the known solution can be used only for certain applications For example, a possible effective use of the radiation generated by the electric gas discharge, in particular double band at 185 nm, to he witness.

By the DE 195 07 189 C2 The known solution relates to a method for medium processing with at least one excimer emitter emitting UV light, through which the medium to be treated is passed, wherein the medium to be reprocessed in a loop reactor at least once is guided through the excimer radiator, wherein further within the loop reactor at least one biological, mechanical, physical or chemical cleaning stage is present, through which the medium to be reprocessed is also performed at least once, which is the excimer radiator upstream or downstream. The medium to be treated, usually in the form of water, is passed through the entire reactor as a common propulsion jet, this propulsion jet, for example driven by a centrifugal pump, traversing an open reactor space in free fall. The flow or fall rate of the medium to be treated through the biological, mechanical, physical or chemical purification stage is defined in the order of about 0.3 m / sec in order not to rinse off the immobilized biomass from the vegetation carrier or growth substrate.

by virtue of the gravity-related case of the medium to be treated (water) through the loop reactor as an open system can its residence time do not set exactly, in particular specify undefined. Further are the possibilities of influence on the medium to be processed due to the gravitational Drop distance reduced in the open reactor system.

outgoing From this prior art, the invention is based on the object to further improve the known technologies that yourself the desired ones Spectral yields by change the plasma parameter (gas type, pressure, power and frequency of the high voltage) can be adjusted in a wide range that the generation of the Radiation by plasma discharge occurs in a large lumen, and that the Device long lasting and thus trouble-free, as well as inexpensive to operate is. This task solves a device having the features of claim 1 in his Entirety.

Thereby, that according to the characterizing Part of claim 1, the fluid within the reaction chamber in tubes of radiolucent Material led is achieved, is a self-contained reaction system, and the generation of radiation by plasma discharge can be large-scale in the device done. The said energy input means in the form the cylindrical electrode and at least one Gegenelek electrode is used the electromagnetic radio frequency entry into the reaction chamber, wherein in the device according to the invention the plasma parameters such as gas type, pressure, power and frequency easy to set the high voltage in a wide range, and with the device according to the invention it is possible the fluid to be treated directly through one of large area electrodes generated radiation field within the reaction chamber via the fluid-carrying To guide pipes, so that in a very large volume nevertheless high energy flows can be generated are and on big surfaces can be distributed.

Consequently It can not come as with the known solutions to that with increasing distance between radiation source and target (fluid) a strong weakening The radiation occurs, which is ultimately associated with a high electrode wear. In particular, the electrode wear is due to the uniform energy output over the huge surfaces the cylindrical electrode and the adjusting itself Volumes avoided, so that the inventive solution reliable and cost-effective is working. The latter also applies if the energy input by plasma excitation by means of microwave, wherein the pertinent microwave input on the cylindrical Electrode, for example via a side opening the same takes place in the reaction chamber.

There the fluid within the reaction chamber is guided in tubes of radiation-permeable material, is the medium or fluid no longer forced to As shown in the generic state of the art, a free Traps fall due to gravity caused in no time, but Rather, by a cleverly chosen pipe guide the residence time within the irradiation device defined defined in a wide range become. Also can different media in separate tubes within the Reaction chamber to be treated. Furthermore, an influence the reaction over Catalysts in the individual tubes possible, as well as over externally Radiation-permeable metal coatings applied to the tubes.

In a preferred embodiment of the device according to the invention, the reaction chamber is bounded on the end by two end caps, to which the electrode voltage can be applied, wherein the one end cap is conductively connected to the cylindrical electrode and the other end cap with the respective counter electrode. Preferably, it is further provided that the cylindrical electrode is made of a UV-radiopaque material, for example, non-sputtering material such as aluminum or the like.

at a further particularly preferred embodiment of the device according to the invention the cylindrical electrode is from the termination lid to the respective one Counterelectrode over an insulating device electrically isolated. depending on how the Insulating is procured, for example, in which they have a defined distance, between the free end of the cylindrical Electrode and the cover with the counter electrode can be affect the plasma field in the reaction chamber obvious. Preferably can be provided, the counter electrode in the manner of a center electrode form along the longitudinal axis of the device within the cylindrical electrode extends. Furthermore, the insulating device Made of a Duranglas material that is well-permeable to visible light but not for UV light, so that one can watch the plasma well, but on the other hand from the harmful ones In any case, UV rays are protected is.

at a further particularly preferred embodiment of the device according to the invention is the fluid within the reaction chamber in quartz glass tubes guided. Preferably, it is further provided that the fluid-carrying Tubes traverse the reaction chamber and with their free ends in the two end caps lead and / or several times in the reaction chamber and exit and / or in shape at least one helix are arranged in the reaction chamber. Dependent on of the fluid to be treated, so that also sterilize and / or can be sterilized, can be its length of stay over the flow paths and their length safely adjust and master.

at a further preferred embodiment the device according to the invention are in the fluid-carrying Pipes fillings out radiolucent Material introduced. In this way, the specific can be on the photoreaction Increase radiation transition area. Of others can on the packing suitable catalysts for heterogeneous Catalysts are fixed. So can Including degradation reactions oxidative degradation reactions can be accelerated by catalysts. Particularly suitable for this are Catalyst materials such as platinum, palladium, titanium dioxide and metal phthalocyanines of vanadium or elements of the iron group.

at a further particularly preferred embodiment of the device according to the invention are the fluid-carrying Tubes with a partially radiation-permeable metal casing, preferably provided in the form of a braid as respective counter electrode. To the braid is then formed in the operation of the device so-called Glimmsaum from which the maximum UV radiation emission throughout the plasma.

such to reach an extremely high radiation energy density in the fluid-carrying Tubes, preferably in the form of quartz tubes.

at a further preferred embodiment the device according to the invention are more reaction chambers connected in parallel or in series and thus form an overall device. In this way let yourself from individual building components to reaction chambers in dependence from the task for the fluid to be treated a modular building block principle realize, with the reaction chambers provided inexpensively and at Wear without further ado can be exchanged.

With the device according to the invention let yourself also another method of energy input in addition to perform the electrode assembly, namely the plasma stimulation by microwave. It can be with commercial 2.45 GHz magnetrons generated and by a waveguide with rectangular Cross section are fed in the area of the cylindrical Electrode associated end plate the cylindrical electrode passes through. By means of the magnetron can be thus ignite the plasma with and operate so that the gas discharge is obtained.

in the The following will be the device according to the invention closer to the drawings explained. there show in a schematic and not to scale representation of the

1 in longitudinal section a first embodiment of the device according to the invention, using a cylindrical electrode and a center electrode;

2 a longitudinal section through a second embodiment of the device according to the invention with a cylindrical electrode and the medium-conducting quartz tubes having a metallic braid as a counter electrode.

The in the 1 shown first embodiment of a device is used to carry out photoreactive processes on a fluid (gel, paste, liquids, solutions, gases, etc.), along predetermined flow paths, a reaction chamber 10 crosses. The device is in particular a photochemically induced degradation of orga nical compounds, particles and microorganisms in the fluids possible. Furthermore, a sterilization and / or sterilization of the respective fluid can be achieved in this way. The inner 12 the reaction chamber 10 can be evacuated, which will be explained in more detail below. It is also possible to provide the reaction chamber with a reactive gas. Furthermore, the device as a whole with 14 designated energy-entry means on whose field generates a discharge, the emitted radiation (UV radiation), the fluid through its path in the reaction chamber 10 affected.

In the embodiment of the 1 consists of the energy-entry means 14 from two electrodes 16 . 18 that have an insulating device (insulator) 20 are electrically isolated from each other. One of the electrodes is formed as an anode and the other electrode (counter electrode) as a cathode. The reaction chamber 10 itself is from the outer electrode 16 includes, as well as from the insulation device 20 where both electrode 16 as well as insulation device 20 forming a cylindrical shell and the insulating device 20 engages with its one free end in the inner circumference of the cylindrical electrode 16 one. Furthermore, the reaction chamber 10 end of each one end cap 22 . 24 completed. In the embodiment of the 1 points in the direction of the 1 seen left cover 22 interchanges 26 for that into the reaction chamber 10 fluid to be introduced and delivered, wherein the arrow representation reflects the fluid flow direction. Furthermore, pointing in the direction of the 1 seen right end cover 24 an intake point 28 for gas, preferably in the form of a noble gas such as xenon or argon. In the area of the middle of the left cover 22 this in turn has an outlet point 30 for connecting a vacuum pump, with which the inside 12 the reaction chamber 10 provided with a predetermined negative pressure. The fluid is within the reaction chamber 10 in single tubes 32 made of radiation-permeable material, in particular quartz glass. In the 1 are as media-carrying quartz tubes 32 presented in terms of a simplified illustration only two pieces; in reality, here can be a very large number of fluid-carrying pipes 32 the reaction chamber 10 traversing in the longitudinal direction, preferably in a parallel arrangement to the cylindrical electrode 16 ,

Preferably, the end covers 22 . 24 from low-sputtering metals, such as aluminum, aluminum alloys, silicon or cast resin. About the cylindrical electrode 16 and the cylindrical insulating device 20 are the end caps 22 . 24 separated from each other. The material flows to be supplied to the photoreaction are thus replaced by those in the cylindrical reaction chamber 10 located bundles of individual tubes 32 made of radiation-permeable material, in particular quartz glass. The pipes 32 of the tube bundle are thereby vacuum-tight through the end cap 22 . 24 led the reactor. Thus, the fluid to be treated in easy to be operated pipe flow can be passed through a strong and optimized in terms of its task radiation field. By choosing suitable plasma process parameters, such as gas composition, pressure, RF power and frequency, the desired photochemical reactions can be freely adjusted and specified in a wide field. Are a variety of pipes 32 in the reaction chamber 10 arranged finds the deflection and the transfer of the fluid from one to the other tube in the respective end caps 22 . 24 instead of (not shown), which are disc-shaped in the manner of modules for this purpose, and the middle module or the middle disc optionally has, with the extremely arranged module or disc, the respective deflection point for the fluid.

If in the fluid-carrying pipes 32 Even packing made of radiation-permeable material are introduced, can be fixed, for example by the choice of suitable catalyst materials as filler, these for heterogeneous catalysis. The pertinent packing may also be itself a carrier of catalysts, for example by the catalyst material penetrates into the filler material or sintered directly. The fillers are preferably in the tubes 32 used, since here the fluid to be treated is brought into contact with them directly. The fillers are radiation conducting to increase the radiation transfer area to the fluid. In addition, if they form a catalyst property, they allow the acceleration of the desired photoreaction to take place.

In the embodiment of the 1 is in the gas intake point 28 of the end cover 24 a hollow cylindrical counter or center electrode 18 used, which extends along the longitudinal axis of the device and over wide areas in the outer electrode 16 intervenes. If the going there electrode 18 has passage points along its front end and / or along its outer circumference, it is possible via their hollow cylindrical cross section the desired gas entry into the reaction chamber 10 to induce.

The overall device can be modular; In particular, predeterminable lengths and cross sections of cylindrical electrodes can be used in the manner of a construction kit 16 , Isolatoreinrichtungen 20 and end caps 22 . 24 be available.

In the embodiment of the 2 this is only explained in so far as they differ significantly from the embodiment of the 1 different. The same components are in 2 numbered with the same reference numerals as in the 1 if they correspond to each other. In the embodiment of the 2 was dispensed with the center electrode and the counter electrode 18 is now formed over metal wires, preferably in the form of a braid, which the quartz tubes 32 Surrounded along its outer periphery. To the pertinent braiding 34 then forms the so-called Glimmsaum, which forms the maximum UV radiation emission in the entire plasma. In this way you can get an extremely high radiation energy density in the quartz tubes 32 reach for yourself. In non-illustrated embodiments of the device according to the invention can individual quartz tubes 32 , which may also be combined into bundles, be surrounded by another filament of a quartz tube. In this way, a longer path for the fluid to be flowed through the device is created and the increase in the residence time allows an improved effect of the plasma field on that in the tubes 32 guided fluid.

Another method, not shown, of the energy entry via the energy entry means 14 the plasma excitation is not exclusively due to the electrode in 16 . 18 but by a microwave. It is preferably generated with a commercially available 2.45 GHz magnetron (not shown) and fed into a metallic annular waveguide of rectangular cross-section (not shown), preferably on the outer electrode 16 is placed and preferably adjacent to the left cover 22 , From this annular microwave waveguide, the microwave then passes preferably through coaxial slots in the shell of the outer electrode 16 in the reaction chamber 10 , in which case by the local ignition then the gas discharge takes place.

For the ignition of a continuous plasma discharge or the triggering of a pulsed plasma discharge, these can be carried out in parallel to the working electrodes 16 . 18 switched capacitors (not shown) and the triggering discharge optionally with additional electrodes (not shown) can be realized.

Synergy effects of specific UV absorption, e.g. B. at 254 nm wavelength with the triggering of chemical processes and by radiationless transitions achieved by heating, the recombinations / reverse reactions disadvantage, can be used by the pulse-wise energy input described above. As a result, it is possible to generate higher temperatures in the microorganisms at the same mean radiation power; the latter is possible without causing increased wear on the electrode pairs used in each case 16 . 18 would come.

Claims (12)

Device for carrying out photoreactive processes in the case of a fluid which has at least one reaction chamber along predeterminable flow paths ( 10 ), which is evacuable and / or provided with a reactive gas and the at least one energy input means ( 14 ) whose field produces a discharge whose emitted radiation occupies the fluid at least over part of its path in the reaction chamber ( 10 ), wherein the energy input means ( 14 ) at least two electrodes ( 16 . 18 ), wherein the reaction chamber ( 10 ) at least partially from a cylindrical electrode ( 16 ) and wherein at least one counterelectrode ( 18 ) within the reaction chamber ( 10 ) and from the cylindrical electrode ( 16 ) is electrically isolated, characterized in that the fluid within the reaction chamber ( 10 ) in pipes ( 32 ) is guided from radiation-permeable material. Apparatus according to claim 1, characterized in that the reaction chamber ( 10 ) end of two end covers ( 22 . 24 ) is limited, to which the electrode voltage can be applied and that the one end cover ( 22 ) with the cylindrical electrode ( 16 ) is conductively connected and the other end cover ( 24 ) with the respective counterelectrode ( 18 ). Device according to claim 2, characterized in that the cylindrical electrode ( 16 ) from the end cover ( 24 ) with the respective counterelectrode ( 18 ) via an insulating device ( 20 ) is electrically isolated. Device according to one of claims 1 to 3, characterized in that the counter electrode ( 18 ) is a central electrode extending along the longitudinal axis of the device and at least partially within the cylindrical electrode (FIG. 16 ). Device according to claim 4, characterized in that the end caps ( 22 . 24 ) at least connection points for a gas inlet ( 28 ) and a vacuum pump ( 30 ) and / or for the in the reaction chamber ( 10 ) fluid to be delivered and discharged. Device according to one of claims 1 to 5, characterized in that the radiation-permeable material of the tubes ( 32 ) Is quartz glass. Apparatus according to claim 6, characterized ge indicates that the fluid-carrying tubes ( 32 ) the reaction chamber ( 10 ) and with their free ends in the two end covers ( 22 . 24 ) and / or several times into the reaction chamber ( 10 ) and / or in the form of at least one helix in the reaction chamber ( 10 ) are arranged. Device according to one of claims 1 to 7, characterized in that the electrodes ( 16 . 18 ) consist of a non-sputtering material, in particular of aluminum material. Device according to one of claims 1 to 8, characterized in that in the tubes ( 32 ) Packing of radiation-permeable material are introduced, which act in particular as a support material for catalysts. Device according to one of claims 4 to 9, characterized in that via the counter electrode ( 18 ) a reactive gas in the reaction chamber ( 10 ) can be fed. Device according to one of claims 6 to 9, characterized in that the fluid-carrying tubes ( 32 ) with a partially radiation-permeable metal coating, preferably in the form of a braid ( 44 ), as respective counterelectrode ( 18 ) are provided. Device according to one of claims 1 to 11, characterized in that a plurality of reaction chambers ( 10 ) parallel and / or serially connected to form the device.