DE102019125125A1 - Reactor module and oxidation reactor - Google Patents

Abstract

The present invention relates to a photocatalytic oxidation reactor (1) for the oxidation of fluids polluted with organic pollutants, with a mixing element (150) formed by a mesh (300) which has titanium dioxide in the rutile modification.

Description

The present application relates to a reactor module for a photocatalytic oxidation reactor and photocatalytic oxidation reactors for the oxidation of fluids contaminated with pollutants, in particular waste water, which have such a reactor module. The present invention also relates to a method for the oxidation of waste water polluted with pollutants.

The germicidal, disinfecting effect of UV light is known and is often used in water treatment. For example, UV lamps have been used for many years for the disinfection of drinking water and waste water, for the disinfection of work areas in biological laboratories and in air conditioning systems. In contrast to chemical water disinfection processes, UV disinfection is based on a physical process. By absorbing the radiation from the nucleic acids in the cell nucleus of microorganisms, the nucleic acid structure is changed in such a way that replication becomes impossible. The microorganisms, such as bacteria or viruses, lose their ability to infect. With the appropriate dose and wavelength, more than 99.9% of all pathogens can be rendered harmless within fractions of a second.

The high-energy, short-wave UV radiation mainly has a wavelength of up to 280 nm and falls into the so-called short-wave UVC range.

Pure UV disinfection processes are not suitable for the degradation of waste water contaminated with pollutants, for example in the form of organic micropollutants and / or anthropogenic trace substances. Instead, photocatalytic oxidation reactors are required for this.

Such a photocatalytic oxidation reactor is described, for example, by DE 10 2014 009 527 A1 . This consists of a housing body with an inlet and an outlet through which the polluted wastewater flows and inside has a light source in the form of a UV lamp. Such oxidation reactors are specifically manufactured according to customer specifications and are therefore only designed for specified volume flows.

Oxidation reactors are also known which have spherical bodies for thorough mixing of the fluid. Although the concept described brings about an improvement, the result is still not satisfactory. In particular, the manufacture of the spherical bodies is relatively expensive.

The object of the present invention is therefore to provide a concept of a photocatalytic oxidation reactor which is improved compared to the prior art. A further object of the present invention is to provide a photocatalytic oxidation reactor which, with the lowest possible production and operating costs, has an efficiency that is improved compared to the prior art.

• - eine erste Gehäusewand und eine zweite Gehäusewand, die miteinander verbunden und voneinander beabstandet angeordnet sind und einen durchströmbaren Reaktionsraum zwischen sich ausbilden,
• - mindestens ein innerhalb des Reaktionsraums angeordnetes Mischelement,

wobei dieses Mischelement durch ein Geflecht gebildet ist, welches Titandioxid in einer Anatas-Modifikation aufweist.These tasks are solved by having a reactor module

• - A first housing wall and a second housing wall, which are connected to one another and arranged at a distance from one another and form a flow-through reaction space between them,
• - At least one mixing element arranged within the reaction chamber,

this mixing element being formed by a mesh which has titanium dioxide in an anatase modification.

Furthermore, the objects are achieved by oxidation reactors with the features of patent claims 8 and 12 and a method with the features of patent claim 15.

Advantageous embodiments and variants of the invention emerge from the dependent claims and the following description. Thus, the features listed individually in the claims can be combined with one another in any technically meaningful manner as well as with the features explained in more detail in the following description and represent other advantageous embodiments of the invention.

The reactor module according to the invention for use in a photocatalytic oxidation reactor has a mesh as a mixing element for the fluid which flows through the reaction space. The mesh preferably occupies a volume fraction in the reaction space of at least 20%, preferably from 20 to 80%, more preferably from 20 to 60% of the reaction space. The term braid is understood to mean an interwoven network of lines, strands or the like.

According to the invention, the braid can have a core made of metal or glass fiber in cross section. According to the invention, the braid has a layer of titanium dioxide in an anatase modification (hereinafter anatase).

In a particularly preferred embodiment, the braid initially has a first layer of titanium dioxide in a rutile modification on (hereinafter rutile), which is followed by the second layer of titanium dioxide in the anatase modification. The braid can even consist entirely of rutile. Rutile has the advantage that it is extremely hard and wear-resistant.

Anatase has a higher photocatalytic efficiency than rutile, but is less hard. In this respect, although the anatase layer wears out faster in the course of operation, the rutile layer, which is also effective, is preferably located underneath. If the efficiency of the oxidation reactor falls below an acceptable value, it is possible to coat the mesh again with anatase.

The wavelength of the light must be adapted to the selected material composition or the particular photocatalytically active material used.

The mesh can be produced using suitable methods, for example, according to the invention, it can also be a printout from a 3D printer that either already consists of the desired material or desired material composition or is then coated accordingly.

A particular advantage of the battle is that it does not necessarily have to be designed and / or arranged in a planar manner; rather, the braid can also be bent or shaped differently. In particular, it is also suitable for use in a cylindrical oxidation reactor in which it is likewise shaped in a cylindrical shape. Alternatively, it can be designed as a flat surface which is used in a planar reactor, that is to say in connection with plate elements which then form the housing walls.

The mesh can also be designed, for example, folded in a zigzag shape in cross section, so that it has a total height that extends from the first housing wall to the second housing wall. The zigzag shape further improves the mixing of the fluid in the reaction space. In addition, the mesh is held securely between the two housing walls and does not move at all or only minimally during operation.

The braid preferably extends in its longitudinal and transverse orientation over the entire reaction space.

In a special embodiment variant, two braids arranged one above the other can also be provided. Since the light required for the reaction is radiated into the surface of the braid, it is particularly advantageous if the two braids are arranged slightly offset from one another so that the openings and the strands of the braid are not completely congruent. Otherwise, the light entering from the side will not optimally reach the second braid arranged behind the first braid in the direction of radiation, since the strands of the second braid would be in the shadow of the strands of the first braid. If the braids are slightly misaligned, this problem is reduced.

Alternatively, it is also possible to use two or more braids of different mesh sizes. This results in openings of different sizes in the respective braids, so that the incoming light first shines through the braid with the largest openings before it hits the strands of the braid with smaller openings. Depending on the design variant, further braids with even smaller openings can follow in the direction of radiation.

In a particularly advantageous embodiment variant, in addition to the braid or braids, further photocatalytically active mixing elements can also be provided, preferably spherical bodies or balls have proven to be particularly suitable. The spherical bodies can be arranged, for example, between the folds of a folded braid or between two unfolded braids.

The spherical bodies preferably consist of a material selected from the group comprising plastic, glass or metal, in particular stainless steel. A particularly preferred metal is titanium. It has been shown that the spherical bodies preferably consist of the same material or should have the same material structure as the braid or braids.

The spherical bodies can preferably have a diameter of 0.2 to 30 mm, more preferably 3 to 10 mm. They can have the same or different diameters. For example, spherical bodies with a diameter of 4.5 and 6 mm can be arranged in a common arrangement in a ratio of 1: 1 within the flow-through reaction space.

According to the invention, the spherical bodies can be arranged differently. An arrangement in which the spherical bodies are arranged linearly with respect to one another is preferred. In the linear arrangement, the spherical bodies are arranged in a common line both along the width and along the length of the reaction space, both lines enclosing an angle of 90 °. An arrangement in which the spherical bodies are particularly preferred are offset from one another and arranged in a tightest packing.

Furthermore, it is preferably provided that the spherical bodies are arranged in a single-layer arrangement within the reaction space between a housing wall and a braid or between two braids. Furthermore, it has proven to be particularly advantageous if the spherical bodies are fixed in place within the flow-through reaction space, for example by being braced in one of the above-mentioned arrangements by the respective surfaces surrounding them.

In this context, it has proven to be particularly advantageous if the fluid flows through the reaction space from top to bottom, in the so-called falling film process. This has the effect that the balls remain in their position due to the force of gravity and are not whirled up by the fluid flowing through them.

Regardless of the design as a cylindrical oxidation reactor or as a planar reactor, the efficiency of the oxidation reactor can be increased in that the mesh is electrically contacted and is thus able to generate the radicals necessary for the oxidation. In particular with photocatalytically active mixing elements, preferably spherical bodies, additionally arranged in the reaction space, a double-acting system is formed by this combination.

The housing walls delimiting the reaction space can have a structure to improve the mixing. To form the structures, different geometric shapes can be formed in a linear or offset arrangement with respect to one another, with the aim of enlarging the surface area of the housing wall. Preferred shapes are, for example, knob bodies or pyramid bodies. Elongated shapes, such as tears, have also proven to be advantageous.

The housing walls particularly preferably have convex structures which are arranged over the entire surface of the housing walls in an arrangement that is offset and spaced from one another. Due to the spaced-apart arrangement, the housing wall has both planar and curved surface portions. In order to generate the largest possible surface area, the convex structures are almost hemispherical.

In the variant as a cylindrical oxidation reactor, the first housing wall is designed as a translucent inner tube and the second housing wall as an opaque outer tube, the outer tube surrounding the inner tube so that an annular space is formed as a reaction space between the inner tube and the outer tube. A light module is arranged inside the inner tube. The inner tube is thus designed as a light-permeable housing wall so that the UV radiation can get into the reaction space. The outer tube, on the other hand, is not designed to be translucent in order to prevent the light from escaping from the reaction space outside. The outer tube preferably has a mirror coating on the inside in order to reflect the light back into the reaction space.

In the design as a planar reactor, the housing walls are designed as planar plate elements that are connected to one another in a material and / or form-fitting manner. Two light modules are preferably provided which radiate into the reaction space from the outside through the plate elements. The plate elements are designed as translucent housing walls. In the case of plate elements, too, it is advantageous if a mirror coating is applied on the inside in order to reflect the light back into the reaction space.

Both in the case of the embodiment as a cylindrical oxidation reactor or also as a planar reactor, it is advantageous that the light module or modules are arranged outside the reactor module. As a result, the heat generated by the light modules as a result of the electrical power loss is minimized in the reactor and does not radiate into the fluid.

The light modules are preferably arranged in the oxidation reactor in such a way that the entire reaction space is illuminated without shadows.

• - eine wählbare Wellenlänge ohne störende Nebenpeaks
• - eine schonende Verfahrensweise
• - kein Wärmeeintrag in das zu behandelnde Medium
• - selektive Umsetzung und daher keine störenden Nebenreaktionen
• - gefahrlose Niederspannungstechnik
• - lange Lebensdauer und einfache Entsorgung der lichtemittierenden-Dioden
• - Schadstoffabbau weitestgehend ohne Zusatz von aggressiven Chemikalien

A conventional UV lamp is particularly suitable as the light module in the case of a cylindrical oxidation reactor, but the use of one or more LED light modules is also particularly advantageous. The photochemical process with LED technology offers considerable advantages, especially compared to conventional mercury lamp technology. The advantages are in particular:

• - a selectable wavelength without disturbing secondary peaks
• - a gentle procedure
• - no heat input into the medium to be treated
• - Selective implementation and therefore no disruptive side reactions
• - Safe low voltage technology
• - Long service life and easy disposal of the light-emitting diodes
• - Degradation of pollutants as far as possible without the addition of aggressive chemicals

An LED light module to be used according to the invention comprises a cooling element, which is preferably designed in the form of a flat support element, and a plurality of light-emitting diodes arranged on the cooling element, the light-emitting diodes being arranged on one or both sides of the cooling element. The cooling element preferably consists of a material comprising aluminum, stainless steel, graphite, copper, magnesium, brass, silver, tungsten, zinc and / or mixtures thereof.

The light-emitting diodes of the LED-based light module preferably emit light in the wavelength range of 200-1000 nm, more preferably in the wavelength range of 315-400 nm, with a main wave of 365 nm.

The suitable wavelength depends on the type of photocatalytic agent. In the case of titanium dioxide or molybdenum disulfide, a wavelength in the UVA range is required to initiate the chemical decomposition reaction of the organic pollutants, which occurs, for example, via the formation of OH radicals.

The housing walls of the oxidation reactors are preferably made of a material selected from the group comprising light-stable plastics, stainless steel or titanium.

The transparent housing walls preferably consist of a material selected from the group containing natural or synthetic quartz glass, borosilicate glass and / or a transparent plastic, in particular polymethyl methacrylate (PMMA) or polyethylene terephthalate (PET).

In a further advantageous development it is provided that the transparent housing walls are also coated on the inside with the photocatalytic agent. The coating is selected such that the transparent housing walls coated with the photocatalytic agent have a degree of transmission for light, in particular for UV light, in the range from 0.5 to 0.9, more preferably 0.7 to 0.8, so that In addition to sufficient catalytic activity, sufficient irradiance can also be guaranteed.

Due to a combination of housing walls coated with the photocatalytic agent and the braid and possibly the spherical bodies, the reactor module preferably has a surface that is at least 5 times larger than a smooth surface coated on one side with a photocatalytic agent.

In a further particularly preferred embodiment, the surface of the mesh and / or the surface of the housing walls in the reaction space has an average roughness R _a in the range from 20 to 50 μm. Due to the rough surface, through the formation of microturbulences, an improved mixing of the fluid within the reaction space is achieved and the photocatalytic surface is enlarged, so that the efficiency is increased again.

If structured plate bodies are used as the mixing element, it has also proven to be particularly advantageous if the reactor module is designed in such a way that the distance between the mesh and possibly the spherical bodies and the translucent plate element is as small as possible. The distance is preferably less than 3 mm, more preferably less than 1 mm. The distance is particularly preferably 0.1 to 0.5 mm.

The concept according to the invention described here in various design variants can also be used in a modified embodiment for photolysis. For example, a reactor module for a photolysis reactor would differ in that no photocatalytic agent is provided within the reaction space. The mixing element arranged within the reaction space would preferably have a reflective surface which is matched to the corresponding wavelength of the light. Furthermore, in an advantageous variant, some of the inside surfaces could have a reflective coating. The mixing element arranged within the reaction space could be expanded to include a dynamic mixing element. Depending on the photochemical reaction that should be able to be implemented with such a photolysis reactor, the LED-based light module could continue to emit light in the wavelength range from 200 nm (UV) to 1000 nm (IR).

The present invention is explained in more detail below on the basis of exemplary embodiments. These exemplary embodiments are to be understood as exemplary and not restrictive and are intended to enable the person skilled in the art to carry out the invention. In particular, these are schematic representations that are not true to scale.

• 1: eine schematische Prinzipdarstellung einer ersten Ausführungsvariante eines erfindungsgemäßen photokatalytischen Oxidationsreaktors als Planarreaktor im Längsschnitt,
• 2: eine schematische Prinzipdarstellung einer zweiten Ausführungsvariante des erfindungsgemäßen photokatalytischen Oxidationsreaktors in zylinderförmiger Ausführung,
• 3: eine schematische Darstellung eines Geflechts in Zickzack-Form,
• 4: eine schematische Prinzipdarstellung einer dritten Ausführungsvariante eines erfindungsgemäßen photokatalytischen Oxidationsreaktors als Planarreaktor mit Kugelkörpern im Längsschnitt,
• 5: eine schematische Prinzipdarstellung zweier Geflechte mit unterschiedlicher Maschenweite,

Show it:

• 1 : a schematic representation of the principle of a first embodiment of a photocatalytic oxidation reactor according to the invention as a planar reactor in longitudinal section,
• 2 : a schematic representation of the principle of a second embodiment variant of the photocatalytic oxidation reactor according to the invention in a cylindrical design,
• 3 : a schematic representation of a mesh in zigzag form,
• 4th : a schematic representation of the principle of a third embodiment of a photocatalytic oxidation reactor according to the invention as a planar reactor with spherical bodies in longitudinal section,
• 5 : a schematic representation of the principle of two braids with different mesh sizes,

1 shows a schematic representation of a first embodiment of the photocatalytic oxidation reactor according to the invention 1 in longitudinal section. This is designed as a planar reactor. Since this is a schematic representation, purely structural parts that are not essential to the invention, such as a housing, holders, seals, electrical lines, an LED transformer, etc., are in some cases not shown.

The oxidation reactor 1 has a reactor module 100 as well as two LED-based light modules 200 that emit light in the wavelength range from 315 - 400 nm and into a flow-through reaction chamber 140 irradiate.

The reactor module 100 comprises two rectangular translucent plate elements 110 , 111 , which are connected to one another by means of spacer elements (not shown). Both plate elements 110 , 111 consist in the present case of a borosilicate glass.

The two plate elements face on the inside 110 , 111 a photocatalytic titanium dioxide-based coating extending over its entire surface 120 , wherein the titanium dioxide is in the anatase modification. The thickness of the photocatalytic coating 120 is designed in such a way that each of the two translucent plate elements 110 , 111 has a transmittance for UV light in the range of 0.7-0.8.

Inside the flow-through reaction space 140 is as a static mixing element 150 A braid 300 is arranged in a stationary manner. An undetectable fluid flows through the reaction space 140 from an inlet 141 to an outlet 142 and is irradiated in this with UV light. The direction of flow is indicated by the arrows.

The entire surface of the mesh 300 has a photocatalytic titanium dioxide-based coating 120 on, wherein the titanium dioxide is in the anatase modification.

Outside the flow-through reaction chamber 140 is on rectangular translucent plate elements 110 , 111 one LED-based light module each 200 arranged, which emits UVA light with a main wave of 365 nm and the reaction space 140 Illuminates without shadows. The LED-based light module 200 consists of a rod-shaped cooling element 210 made of aluminum, on which a plurality of light-emitting diodes 220 are arranged on one side.

2 shows a schematic representation of the principle of a second embodiment variant of the photocatalytic oxidation reactor according to the invention 1 . The structure of a cylindrical oxidation reactor is shown 1 in a perspective schematic representation, the essential elements being shown pulled apart along their longitudinal axis for a better view.

A translucent inner tube can be seen 320 and an opaque outer tube 330 , between which the reaction space 140 in the form of an annulus 340 trains. Inside the annulus 140 the braid 300 is arranged. The LED light module 200 runs inside the inner tube.

3 shows a preferred embodiment of the braid 300. This was brought into a zigzag shape, which further promotes mixing of the fluid flowing through it. The braid 300 is in 3 shown flat, but it can also be brought into a cylindrical shape, so that also in the variant according to FIG 2 the zigzag-shaped braid can be used.

4th illustrates an example of a variant in which additional mixing elements 150 in the form of spherical bodies 156 are provided. Spherical bodies with slightly different diameters can be seen, of course only spherical bodies of the same diameter can be used according to the invention. The spherical bodies 156 are arranged between fold lines of the mesh 300 and held there. The spherical bodies 156 are preferably each arranged in rows, so that in an oxidation reactor 1 several rows of spherical bodies 156 are arranged. The rows of spherical bodies 156 can be aligned either in the direction of flow, obliquely or transversely to the direction of flow of the fluid.

5 shows that when using several braids 300 in a single reaction space 140 different mesh sizes of the braids 300 are advantageous. It is essential that the rear mesh 300 in the direction of illumination should be shaded as little as possible by the mesh 300 arranged in front of it. Knows that in On the other hand, with regard to the light propagation, the front first mesh 300-1 has larger mesh sizes, the light radiates through the meshes and strikes the mesh 300-2 arranged behind it with a smaller mesh size.

What is not shown is that the braid 300 can also be electrically contacted in order to thus bring about the formation of free radicals.

A major advantage of the invention is that OH radicals can be generated without the addition of further chemical agents, which leads to more environmentally friendly oxidation.

List of reference symbols

1

Oxidation reactor

100

Reactor module

110

Plate element

111

Plate element

120

photocatalytic coating

121

photocatalytic coating

140

Reaction space

141

inlet

142

Outlet

150

Mixing element

156

Spherical body

200

LED-based light module

220

light emitting diodes

320

Inner tube

330

Outer tube

340

Annulus

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102014009527 A1 [0005]

Claims (16)

Reactor module (100) for use in a photocatalytic oxidation reactor (1) having: - a first housing wall (110) and a second housing wall (111), which are connected to one another and are arranged at a distance from one another and form a flow-through reaction space (140) between them, at least one mixing element (150) arranged within the reaction space (140), characterized in that this mixing element (150) is formed by a mesh (300) which has titanium dioxide in an anatase modification. Reactor module (100) after Claim 1 , characterized in that the braid (300) is coated with titanium dioxide in a rutile modification, which is followed by a layer of titanium dioxide in an anatase modification. Reactor module (100) after Claim 1 or 2 , characterized in that the braid (300) is made of metal. Reactor module (100) after Claim 1 or 2 , characterized in that the braid (300) is formed from glass fiber. Reactor module (100) according to one of the Claims 1 to 4th , characterized in that spherical bodies (156) with a photocatalytically active surface are also arranged within the reaction space (140). Reactor module (100) according to one of the Claims 1 to 5 , characterized in that the mesh (150) is folded in a zigzag shape in cross section. Reactor module (100) according to one of the Claims 1 to 6th , characterized in that the fluid flows through the reactor module from top to bottom in the falling film process. Oxidation reactor (1) with a reactor module (100) according to one of the Claims 1 to 7th , characterized by a design as a cylindrical oxidation reactor (1), characterized in that - the first housing wall (110) is designed as a translucent inner tube (320) and the second housing wall (111) as an opaque outer tube (330), the outer tube (330 ) surrounds the inner tube (320) so that an annular space (340) is formed as a reaction space (140) between the inner tube (320) and the outer tube (330), a light module (200) is arranged within the inner tube (320). Oxidation reactor (1) after Claim 8 , characterized in that the wall of the inner tube (320) facing the annular space (340) is mirror-coated. Oxidation reactor (1) after Claim 8 or Claim 9 , characterized in that the wall of the outer tube (330) facing the annular space (340) is mirror-coated. Oxidation reactor (1) according to one of the Claims 8 to 10 , characterized in that the walls of the inner tube (320) and the outer tube (330) facing the annular space (340) are coated with a photocatalytic agent and have a transmittance for UV light in the range from 0.5 to 0.9 Oxidation reactor (1) with a reactor module (100) according to one of the Claims 1 to 7th , having at least two transparent plate elements (110, 111) connected by means of at least one spacer element (130, 131), between which the flow-through reaction space (140) is formed, Oxidation reactor (1) after Claim 12 , characterized in that the plate elements (110, 111) are coated on the inside with the photocatalytic agent and have a degree of transmission for UV light in the range from 0.5 to 0.9 Oxidation reactor (1) according to one of the Claims 8 to 13th , characterized in that the light module is designed as an LED-based light module (200). A method for the oxidation of fluids polluted with organic pollutants comprising the steps: - Providing a photocatalytic oxidation reactor (1) according to one of the Claims 7 to 13th - introducing a fluid contaminated with organic pollutants, and - oxidizing the fluid polluted with organic pollutants, so that a pollutant-free fluid is obtained. Procedure according to Claim 14 , the introduction of the fluid contaminated with organic pollutants taking place in such a way that the fluid passes through the oxidation reactor from top to bottom.

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