EP3236710A1 - Method and device for thermal processing of solids - Google Patents

Abstract

The invention relates to an apparatus and a method for the thermal treatment of solids. The device (100) comprises a binary electrode arrangement (20), which can be arranged on a surface (A) of a solid (10) and in each case has at least two electrodes (22, 24) which are electrically insulated from one another. The electrode structure (20) is electrically conductively connected to a high-frequency voltage source (30) which is designed to apply to the electrode arrangement (20) a high-frequency voltage with a frequency between 100 kHz and 50 MHz. The device (100) comprises a holding device (42), which is designed to allow a translatory movement of the electrode assembly (20) along the surface (A) of a solid (10). The method is characterized in that by applying a high-frequency voltage to the electrodes (22, 24) of the electrode assembly (20) an alternating electric field in the solid (10) is generated and by this alternating field heating of the solid (10).

Description

The invention relates to a method and a device for the thermal treatment of solids. In particular, the present invention relates to a method and apparatus for efficient, direct volume and temperature distribution controlled thermal treatment of solids by means of radio frequency energy. This can u. a. for a chemical-free wood protection, the drying or the decontamination of solids are used.

Technological background of the invention

The course of many technical processes can be significantly influenced by the temperature, since a variety of physical and chemical parameters are more or less temperature dependent. In the context of construction and renovation, this includes the drainage of buildings, the discharge of chemicals from building materials or the thermal control of wood pests. In the latter case, reaching a lethal temperature of about 55 ° C is an alternative to the use of toxic chemicals as wood preservatives [ C. Hoyer et al., Chem. Ing. Technique 86 (2014) 1187 ]. In living and utility rooms, the quality of the indoor air is given increasing importance. Here the use of chemicals is often to be seen critically, whereby thermal treatment methods gain in importance.

From the variety of problems in the construction industry, in building renovation and in other applications, the application potential of the invention focuses on the treatment of more or less extensive sheet materials from solids that are accessible only on one side or would be accessible on both sides only with great effort. Particular preference is given to material thicknesses of up to 10 cm. Examples include parquet and other wooden floors, wall paneling and other wall coverings or screed floors. Often a need for remediation can be limited to these building structures, so that there is a need for adequate methods for the treatment of relatively thin, extensively extended solid structures that make it possible, for example, wood pests thermally combat or remove water and chemicals from these materials. For an efficient and gentle treatment it is necessary on the one hand to achieve as fast as possible homogeneous temperature distributions and on the other hand to control the heating precisely in order to avoid material damage by local overheating. For sensitive surface coatings such as paints or veneers, it is often desirable to keep the surface temperature low, possibly even lower than the bulk temperature in the solid matrix. The present invention aims to provide a corresponding method based on direct dielectric heating using high frequency energy. The device allows a non-invasive treatment, which also allows deployment options in the field of monument protection and the use of art objects.

In the prior art, there are a number of methods that allow heating of the volume of material by heat conduction from the surface. Mentioned here are the hot air process in which the surface is heated by a sweeping air stream, the use of hot plates or electric blankets or the infrared process, in which the primary energy absorption is practically also limited to the surface. The heat conduction into the structure to be treated is determined by the parameter specific thermal conductivity, which is often low, especially for dry materials, which leads to long heating times. Basically, the heat flow is stronger, the higher the temperature gradient, d. H. the temperature change per distance, and hence the higher the surface temperature set by the above methods. Overheating on the surface, however, are limited by material reasons, especially since thermal damage to these visible surfaces would be particularly critical. For extensive areas such as parquet floors in prestigious rooms, a gradual treatment is necessary for most treatment methods. This means that treatment equipment such as hotplates or IR emitters must be moved according to specific time regimes to cover the entire area. A hot air treatment of the entire surface and the rooms, however, has the disadvantage that high temperatures are often harmful for often existing there other objects (eg paintings).

In order to avoid the disadvantages of an inhomogeneous temperature distribution, overheating of the surface and a slow passive heating of the interior via the thermal conductivity, direct heating methods such as the use of microwaves (MW) have recently been introduced. EP 1 374 676 B1 ] or radio waves (RW) [ DE 20 2010 001 410 U1 ], for which a heat generation in the volume of the solid is characteristic. The warming is based on the interaction of the electromagnetic waves used with frequencies usually in GHz (for MW) and MHz range (for RW) with polar structures in the solid. For microwave heating, the reorientation of the water molecule, which is an electric dipole, is the dominant mode of action in most applications. The interaction of the reoriented water molecule with its environment, which can be described as internal friction, creates heat. For this reason, moist materials can generally be heated well by MW. For dry materials, however, the method is often less suitable. The temperature profiles are usually very inhomogeneous for MW heating, causing local overheating to occur. This is due on the one hand to the low penetration depths of the MW and on the other hand to interference phenomena or the radiation characteristics of the horn antennas used. As a result, overheating at different surface positions, which is lower but nevertheless significant and often critical, is noticeable in comparison to conventional methods. Although the RW method according to the described prior art leads to much more homogeneous temperature profiles, the two-sided arrangement of electrodes with respect to the material to be heated, however, leads to limitations in the applicability of the method, especially in only one-sided accessible structures, as described above , Further advantages of the use of RW over MW in the context described are the higher flexibility with regard to the materials to be heated and their moisture contents and the higher energy efficiency through the use of an electronic matching network. These aspects predestine the RW method for use on flat, not too thick structures for the purpose of chemical-free wood protection, drying or decontamination, if it is possible to realize the energy input into the corresponding materials with one-sided accessibility.

It is therefore an object of the present invention to provide a method and a device for the efficient, directly volume-related and with regard to their temperature distribution controlled thermal treatment of solids by means of high-frequency energy, which take up the said advantages of the radio-frequency heating and thereby the disadvantages described overcome the prior art and provide a deployable device that allows to use the RW method for the applications mentioned successfully. The still existing technological gap, in particular with regard to an adequately realizable electrode arrangement, should be closed by the present invention. The disadvantages of the prior art are overcome and a deployable device can be provided, which allows to use the RW method for the applications mentioned successfully.

Summary of the invention

These objects are achieved by the independent claims. Preferred embodiments of the invention are contained in the subclaims.

The device according to the invention comprises a binary electrode arrangement that can be arranged on a surface of a solid, each having at least two electrically isolated electrodes (electrode structure), wherein the electrodes are preferably in a planar plane parallel to the surface of the solid to be treated. The electrode structure is electrically conductively connected to a high-frequency voltage source, which is designed to apply to the electrode arrangement a high-frequency voltage with a frequency between 100 kHz and 50 MHz. The device according to the invention is designed such that a high-frequency electric field is established within a structure (solid) arranged under the device. The device according to the invention comprises a holding device, which is designed to allow a translatory movement of the electrode arrangement along the surface of a solid.

Furthermore, it is preferred that the electrodes are formed as intermeshing comb-like structures, wherein each of the structures comprises a plurality of individual electrodes (fingers) which are interconnected via a common web. In this case, it is preferable that the longitudinal axes of the individual electrodes are parallel or substantially parallel to each other. Furthermore, it is preferred that the longitudinal axes of the webs run parallel or substantially parallel to one another.

It is a device for efficient thermal treatment in volume by a arranged on the surface of the structure to be heated binary electrode structure for feeding high-frequency energy in a predominantly flat extended solids, which with a high-frequency power source, the voltages with a frequency in the range generated between 100 kHz and 50 MHz, is electrically connected, and generates a three-dimensional electric field outside the electrode plane in the solid to be treated, which leads to a heating in the volume. Electrodes of one polarity can also be connected in groups, in which case a contacting takes place between the individual electrodes.

Under such a binary electrode arrangement is to be understood a two-part arrangement of individual electrodes to two electrode groups. The electrodes of the individual groups are each electrically conductively connected to each other, but the two electrode groups of the binary electrode arrangement are electrically isolated from each other. Due to the mutual position of the individual electrodes of the electrode arrangement, a common main axis can be defined. This main axis particularly preferably extends along the longest symmetry axis of the electrode arrangement.

In particular, the present invention may include a binary substantially two-dimensionally-configured electrode structure electrically connected to a high-frequency generator providing a high-frequency voltage having a frequency in the range between 100 kHz and 50 MHz. Preference is given to a frequency range of 1 MHz to 30 MHz. Very particular preference is given to frequencies which are released for industrial, scientific and medical applications (ISM frequencies). The electrode structure is designed such that the coupling of the electromagnetic waves into the structure to be treated takes place in such a way that, compared to conventional methods based solely on heat conduction, a more homogeneous dielectric heating can be observed, since the heating takes place directly in the volume. Preferably, the device further includes an electronic matching network connected between the RF generator and the electrode system to minimize or eliminate the RF power reflected from the generator. An electromagnetic shield which significantly reduces the emission of electromagnetic waves from the electrode structure into the room is also part of preferred embodiments of the device according to the invention. In addition to these basic components, preferred implementations of this device advantageously include one or more temperature sensors and / or automatic system control devices via a computer system and / or devices for automatically moving the device over the surface to be treated and / or devices for automatic temperature control of the surface.

The idea of the present invention is to achieve by using the device according to the invention with only one-sided accessibility of the solid to be treated temperature profiles, which are more homogeneous compared to other methods and thus faster to achieve the targets. This usually means that even the primary energy input in most materials has a penetration depth of some Centimeters. It even succeeds in keeping the surface temperature lower than the temperature below the surface in the volume of the solid.

The binary electrode system is advantageously designed so that in one area of the device grounded electrode parts (so-called "cold" electrodes) and live electrode parts (so-called "hot" electrodes) alternate (interdigital structure) and thereby in the underlying material a high-frequency electromagnetic Field is generated. If the distance between the electrodes is of the same order of magnitude as the width of the electrodes, an electromagnetic field is generated whose distribution satisfies the requirements of sufficiently uniform heating particularly well. A particularly preferred and structurally robust design of this binary electrode system is an interlocking comb structure (double comb structure). The electrode arrangement therefore comprises two intermeshing comb structures. In this case, a comb structure is to be understood as meaning a structure in which the individual electrodes of the electrode arrangement are arranged in comb-like fashion as tines or teeth next to one another along an electrically conductive web. In particular, the web can be aligned parallel to the main axis of the electrode assembly. The comb structure can be formed on one or two sides, d. H. along the ridge, the individual electrodes can point along a single ridge either in only one direction or in two independent directions. Preferably, in the two-sided formation of the comb, the two directions are within a common plane. An interlocking comb structure is understood to mean any mutual arrangement of two such comb structures, in which the individual prongs of both combs are interlinked without electrical contact with one another.

The field strength maxima at the edges of the electrodes can be reduced by using bevelled or rounded electrodes. This change significantly reduces overheating at the edges of the electrodes without significantly limiting the effect of coupling into the material. To achieve the desired change already bending radii or bevels of a few millimeters are sufficient. On the other hand, half-round electrodes or electrode parts formed opposite the surface are less suitable since the energy injection would be concentrated too much on the center of the electrode (along the contact line). Preferably, therefore, the electrode assembly comprises a surface which is arrangeable on the surface of the solid, wherein the edges of the surface facing the surface of the solid are rounded or bevelled. In particular, said surface may be about the surface act, which can be arranged on the surface of the solid so that a maximum large surface of the solid is covered by the electrode assembly. This surface has edges with respect to adjacent surfaces of the electrode assembly, which may be rounded or bevelled. When a high-frequency voltage is applied to the electrode arrangement, an alternating electromagnetic field is generated whose field lines usually end perpendicular to the individual surfaces of the contacts. At tips, a concentration of field lines usually occurs. By rounding off or chamfering the edges, a more homogeneous distribution of the field lines in the solid can be achieved, since in this way the field strength maxima at the edges of the electrodes can be reduced and at the same time an improved and more homogeneous penetration of the area between the contacts can be achieved. It is furthermore preferred that all edges of the electrodes facing the surface to be treated are rounded off or bevelled.

The electrodes may be perforated in order to ensure unhindered removal for the cases of drying or chemical discharge from the heated structure and thus to prevent reconstitution. Preferably, the electrode assembly is thus perforated at least in some areas. In this case, individual electrodes of the electrode arrangement can be completely or partially perforated. The perforation may preferably be circular, square, rectangular or hexagonal. Also possible are mixed forms thereof as well as a number of different sized perforation passages. In regions of high field line density, an increase in the transportability in favor of a more homogeneous field line distribution can be achieved by varying the perforation density and / or type. If necessary, a suitable adsorbent can be located directly at the electrodes, which can bind water or pollutants and thus support the discharge. For organic pollutants it is possible with preference to use activated charcoal beds or activated carbon fleeces, which in an advantageous embodiment are connected directly to the electrodes.

The electrode arrangement according to the invention can be applied to the surface of a solid for carrying out the method according to the invention and can be moved in translation along the surface of the solid to be treated. This application can be done as a direct contact between the respective opposing surfaces. Also possible is a small distance between the respective surfaces; preferably smaller than 1 mm, smaller than 2 mm, smaller than 5 mm or smaller than 10 mm. In order to protect the contacts and the surface of the material to be treated against soiling and / or damage during a translatory movement of the electrode arrangement, at least in particular claimed areas a protective layer, for example, from a plastic polymer such as PTFE or PE or from a textile layer such as felt, be applied. Preferably, therefore, the electrode assembly comprises a surface which can be arranged on the surface of the solid, wherein the surface is at least partially protected by a protective layer. It is furthermore preferred that the surfaces of the electrodes facing the surface to be treated are coated in such a way that damage to the surface during the movement during the treatment is prevented or substantially reduced.

In order to ensure the electromagnetic compatibility of the arrangement, the binary electrode system may preferably be completely or partially enclosed by an electromagnetic shield above the surface to be treated. As shielding materials, for example, solid metal sheets, gauzes or metal-coated plastic films are suitable. Preferably, the electrode assembly is at least partially surrounded by an electrically conductive shield. It is furthermore preferred that the electrodes are surrounded by a shield consisting of an electrically conductive material such as, for example, solid sheet metal, gauze or metal-coated foil, so that an electromagnetic radiation into the space is significantly reduced or eliminated.

In addition to the spatial expression of the electromagnetic field in the material to be heated from a procedural point of view is a continuous or quasi-continuous translational movement of the electrode assembly a way to homogenize the heating profiles. This can be done for example by a corresponding manual movement of the device along the surface of the solid. Preferably, however, the device comprises a means for automated translational movement of the electrode assembly. This means can be provided for example by a correspondingly mounted actuator platform. By a corresponding activation or pre-programming of the movement of at least the electrode arrangement, a homogeneous heating of the solid can be achieved. Preferably, the device has a means for translational movement of the electrode assembly with the periphery such as shielding over the treated surface.

Since the highest field strengths and thus the highest heating rates occur at the edges of the binary electrode structure, it is advantageous to align the structure of the electrodes so that, in the continuous movement for the heating of a larger area as far as possible no longer positioning of an edge at one point of the to be treated substrate occurs. This procedure is intended to better illustrate a parquet floor be explained in a rectangular space. To treat the entire surface, it makes sense to move a rectangularly designed treatment device parallel to two opposing walls. If the electrode structure is surrounded by a parallelepiped shield, which is moved parallel to the wall, it would be advantageous to arrange the binary electrode structure at an angle of 45 ° to the boundaries of the shield and thus to the direction of movement. Preferably, the electrodes are therefore arranged neither parallel nor perpendicular in relation to the preferred direction of movement, with an arrangement of the electrodes at an angle of 45 ° is preferred.

Preferably, the electrodes of the electrode arrangement are arranged perpendicular to the main axis, wherein the length of the electrodes varies along the electrode arrangement. It is particularly preferred that the length of the electrodes varies linearly along the electrode arrangement. In particular, a device is preferred that has a maximum electrode length in the center of the electrode assembly and in which the length of the electrodes adjacent thereto on either side decreases linearly towards the outer ends of the electrode assembly. Furthermore, it is preferred that the shield of the electrode assembly has a square base, in which the aforementioned embodiment can be arranged with both sides sloping electrode length such that the main axis of the enclosed electrode structure extends through two opposite corner points. Such a device is preferably moved along the sides of the square shield, so that in this case an arrangement is at an angle of 45 ° to the edges of the shield.

Such a design results in that, with a continuous movement of the arrangement parallel to the wall, each position on the surface to be treated is swept over by an edge only for a short time. This would not be the case with a parallel or rectangular arrangement of a comb structure relative to the direction of movement and to the frame. Of course, other geometries of the arrangement according to the invention are possible taking into account the mentioned boundary conditions. All of these arrangements have in common that a three-dimensional electric field is established in the structure to be treated by means of a substantially two-dimensional, planar electrode arrangement, which enables dielectric heating in the volume as a result of the energy absorption. The movement of the electrode assembly and the immanent heat conduction in the solid contribute to a homogenization of the temperature profile, which should be taken into account when choosing the treatment time and treatment intensity (power input density). Also a pulsed energy input with the utilization of the heat conduction in the phases without Radio wave application is a procedural option for homogenizing the temperature distributions in the solid.

For an automated and time-efficient treatment process, continuous measurement of heating is an advantage. Since in the context of application, the introduction of sensors in the structure to be treated itself is usually not possible, the non-contact measurement of the surface temperature between the electrodes should be used by means of optical sensors for control. For this purpose, preferably pyrometric sensors can be integrated into the device. Particularly preferred is the additional integration of a computer system that regulates the RF power and / or the speed of movement of the device over the structure to be treated on the basis of the measured temperature or several measured temperatures to avoid overheating of the surface and at the same time by ensuring a minimum temperature to ensure the success of the treatment.

However, although the device of the present invention allows heating of the volume, the penetration depth of the heating can also be controlled by the design of the electrode structure. This is a great advantage for cases in which the substrate under the wood structure to be treated is unknown and heating of this part of the building structure is to be minimized.

Preferably, the device according to the invention comprises a control device for controlling the surface temperature of the solid. The regulating device may comprise a means for determining the surface temperature of the solid. This may be at least one, preferably electronic or optical, sensor that detects the surface temperature. The regulating device may comprise a means for determining the surface temperature of the solid. The regulating device may comprise a means for determining the electric field strength. This may be at least one sensor that detects the electric field strength. The regulating device may comprise a means for evaluation and control. This may be, for example, a computer system which is designed to evaluate the measurement signals of the individual means for determining and controlling the entire apparatus. In particular, the means for determining the surface temperature and / or the means or means for determining the electric field strength can be connected to the means for evaluation and control for evaluation. Furthermore, the means for translatory movement and / or the high-frequency voltage source can be connected to the means for evaluation and control for control. By the means for evaluation and control Thus, depending on certain variables, the RF power applied to the arrangement and / or the translational motion profile can be adapted such that a substantially homogeneous processing of the solid is made possible. In this respect, the means for evaluation and control in combination with sensors can provide control and regulation of the thermal treatment of solids. In particular, the RF power applied to the electrodes can be regulated as a function of the measured surface temperature.

It is further preferred that the device comprises at least one means for cooling the surface of the solid, which allows cooling of the surface of the dielectrically heated solid. This means for cooling the surface of the solid may also be regulated by the means for evaluation and control. Preferably, the means for cooling the surface may be a device for air guidance. The device for air guidance may, for example, be an active system in which air is supplied to individual subregions of the electrode arrangement. The supplied air can be generated locally as a flow of air from a plurality of fans or supplied by a corresponding air flow control the individual sections. The airflow may preferably be generated via a single main fan. The supplied air can be additionally cooled by a cooling device. For the guidance of the air flow for cooling, a perforation in the electrode structure can also be used.

Preferably, an electronic matching network is connected in the electrically conductive connection between the electrode arrangement and the high-frequency voltage source for reducing the high-frequency power reflected back from the electrode arrangement to the high-frequency voltage source. In particular, an electronic matching network, a so-called matchbox, may be connected between the RF voltage source and the electrode arrangement in such a way that the RF power reflected from the generator is reduced or eliminated.

The method of the invention is based on the application of the device described above and exploits the resulting advantages in the thermal treatment of solids. In particular, the presented method for the thermal treatment of solids as method steps comprises providing a binary electrode arrangement with at least two electrically isolated electrodes, wherein the electrode assembly is disposed on a surface of a solid, and applying a high frequency voltage to the electrode assembly, wherein an electric Alternating field is generated in a solid and by this alternating field heating of the solid in volume he follows. In an advantageous embodiment of the method, a heating in the volume is achieved without an overheating of the surface takes place. The method according to the invention is suitable for allowing a controlled and direct heating of the structure to be treated and reliably precluding unwanted overheating on parts of the surface and the volume.

Preferably, during a process of using the device of the invention along the surface of the solid, the electrode assembly becomes generally translational, i. in any direction along said surface, moving. More preferably, however, a translatory movement takes place exclusively in directions which do not run parallel to edges of the electrode arrangement. A translatory movement can preferably be carried out manually by a user of the device or by means of a corresponding means for translational movement of the electrode arrangement.

In the method according to the invention can be controlled by a control device, the surface temperature of the solid and adjusted as needed. Preferably, an at least partial cooling of the surface of the solid can take place by the control device. Preferably, the electrode assembly is moved along the surface of the solid manually or automatically translationally. In a preferred embodiment of the method, the cooling of the surface is realized via an air flow, which is guided via perforations in the electrode system. In a further preferred embodiment of the method, water and / or pollutants are bound in a prepared substance that is suitable for receiving these substances. Preferred embodiments of the process are drying agents and / or hydrophobic adsorbents such as activated carbon, for example in granular or nonwoven form.

Brief description of the figures

Figur 1

eine schematische Darstellung einer erfindungsgemäßen Vorrichtung zur thermischen Behandlung von flächig ausgedehnten Feststoffen;

Figur 2

eine schematische Darstellung einer bevorzugten erfindungsgemäßen Elektrodenanordnung nach Fig. 1;

Figur 3

schematische Darstellungen einer weiteren bevorzugten erfindungsgemäßen Vorrichtung zur thermischen Behandlung von flächig ausgedehnten Feststoffen in Aufsicht und in Seitenansicht;

Figur 4

schematische Darstellungen von unterschiedlichen Ausgestaltungen des Querschnitts der Elektroden;

Figuren 5a, 5b

schematische Darstellungen einer Anwendung der erfindungsgemäßen Vorrichtung;

Figur 6

Temperaturprofile für vier unterschiedliche Behandlungsregimes am Beispiel des Feststoffs Holz;

Figur 7

ein Temperaturtiefenprofil für die vier Behandlungsregimes nach Figur 6 mit Angabe der Reichweite für das Erreichen einer Letaltemperatur von 60 °C;

Figur 8

schematische Darstellung einer weiteren erfindungsgemäßen Elektrodenanordnung mit Angabe der Positionen der faseroptischen Temperatursensoren; und

Figur 9

den zeitlichen Verlauf der Temperaturen in 10 mm Tiefe sowie die zeitlichen Verläufe von HF-Leistung und HF-Spannung bei Verwendung der in Figur 8 gezeigten erfindungsgemäßen Vorrichtung.

The invention will be explained below in embodiments with reference to the accompanying drawings. Show it:

FIG. 1

a schematic representation of a device according to the invention for the thermal treatment of extensively extended solids;

FIG. 2

a schematic representation of a preferred inventive electrode arrangement according to Fig. 1 ;

FIG. 3

schematic representations of another preferred device according to the invention for the thermal treatment of extensively extended solids in plan and in side view;

FIG. 4

schematic representations of different configurations of the cross section of the electrodes;

FIGS. 5a, 5b

schematic representations of an application of the device according to the invention;

FIG. 6

Temperature profiles for four different treatment regimes using the example of the solid wood;

FIG. 7

a temperature depth profile for the four treatment regimes FIG. 6 indicating the range for reaching a lethal temperature of 60 ° C;

FIG. 8

schematic representation of another electrode arrangement according to the invention with indication of the positions of the fiber optic temperature sensors; and

FIG. 9

the time course of the temperatures in 10 mm depth as well as the temporal curves of RF power and HF voltage when using the in FIG. 8 shown device according to the invention.

Detailed description of the invention

FIG. 1 shows a schematic representation of a device 100 according to the invention for the thermal treatment of solids 10. The device 100 is shown lying on the surface A of the solid 10, wherein the lateral extent is usually much greater than in the Fig. 1 specified. In particular, in this case a part of the illustrated surface A of the solid 10 is in direct contact with the underside surface B of the electrode assembly 20. However, such a direct contact between the electrode assembly 20 and the surface A of the solid 10 is not mandatory, according to the invention it is sufficient when the field line pattern emanating from the electrode arrangement 20 leads to a corresponding penetration of the solid 10.

The electrode assembly 20 is surrounded upwardly and toward the sides by a shield 40. This serves to focus the field line course on the volume of the solid 10 and to reduce the parasitic radiation into the environment, i. outside the solid 10, significantly reduce. Above the shield 40, a holding device 42 is shown by way of example. In the present case, this serves to facilitate a manual operation of the device 100 for a user of the device 100. The holding device 42 may be designed, for example, as a clamp holder, Umgriffhalterung or screw or plug holder for attaching a telescopic rod head. The holding device 42 may also have a possibility for fixing the electrode arrangement 20 to a means for translational movement of the electrode arrangement 20. By means of a corresponding holding device 42, the electrode arrangement can be moved translationally along the surface A of the solid 10. In particular, according to the invention as complete as possible a successive covering of a continuous surface A of the solid 10 is particularly preferred. In this case, the corresponding movement profile can be chosen freely, however, in particular in the case of manual movement, a zig-zag profile completely covering the surface A of the solid 10 is particularly preferred in the case of the translatory movement. According to the invention, a high-frequency electromagnetic alternating field is coupled into the volume of the solid 10. This RF field is preferably generated by a high-frequency voltage source 30. This can be connected to the electrode arrangement 20 via an electrically conductive connection. Preferably, an electronic matching network 50 for reducing the high-frequency power reflected back from the electrode arrangement 20 to the high-frequency voltage source 30 is connected in the electrically conductive connection between the electrode arrangement 20 and the high-frequency voltage source 30. The illustrated electrode assembly 20 is two interdigitated comb structures. The teeth of the comb and the connecting crosspiece form the individual electrodes. The first web 26 and the second web 28 thereby also constitute conductive electrical connections between the individual teeth of a comb. The high-frequency voltage generated by the high-frequency voltage source 30 is applied to the webs 26, 28 and is therefore also connected to the individual electrodes of the respective Comb connected. According to the invention, a strong electromagnetic alternating field thus forms between the double combs, the field line profile generated in this case preferably penetrating deeply into the volume of the solid 10 and leading to a heating of the material.

FIG. 2 shows a schematic representation of an exemplary inventive electrode assembly 20 according to Fig. 1 , Here, in particular, the interlinked comb-like arrangement of the first electrode 22 and the second electrode 24 as an interdigital structure clearly. The first comb belonging to the electrodes 22a - 22f are electrically connected to each other via the first web 26, wherein the web also acts as an electrode. The electrodes 24a - 24f belonging to the second comb are connected to one another in an electrically conductive manner via the second web 28. This also acts as an electrode. Both combs are electrically completely isolated from each other and have no electrically conductive connection with each other. An indirect connection is made only in the operation of the device 100 by the connection of both combs to the high-frequency power source. The individual electrodes 22, 24 extend along a common main axis X of the electrode assembly 20, wherein in the illustration shown, the first web 26 and the second web 28 also extend parallel to the main axis X of the electrode assembly 20. However, the webs 26, 28 can also be oriented in any other way to the main axis X of the electrode arrangement 20; in particular, the electrodes 22, 24 can also be electrically connected to one another without a fixed web structure. For example, a connection of the respective associated electrodes can also be made by means of individual cable connection or soldering. In the case illustrated by way of example, the webs 26 and 28 lie in a plane with the electrodes 22a-22f and 24a-24f. However, it is also possible that these webs are located substantially above the plane of the electrodes 22a-22f and 24a-24f. In this case, the webs practically do not themselves act as RF electrodes with respect to the material 10 to be treated.

An essential feature of the present invention is the provision of a device for the most homogeneous possible thermal treatment of solids. Therefore, a corresponding degree of homogeneity and uniformity is also particularly preferred when designing an electrode arrangement 20 according to the invention. In particular, the respective geometrical distances, dimensions and angles between the individual electrodes 22, 24 should be uniform. In the presentation of the Fig. 2 This is clear from the fact that here two identical comb structures engage in such a way that the electrode webs are each arranged at the same distance parallel to each other. In particular, the left-side and right-side distances of each individual electrode 22, 24 to their two nearest neighbors are each the same size. The duty cycle between the width of the electrodes 22, 24 and the distance of the individual electrodes 22, 24 can be chosen freely. However, in this case too, a duty cycle which, depending on the high-frequency voltage applied to the electrode arrangement 20 and the respective electrode shape, ensures the best possible implementation of the inventive idea of the method.

FIG. 3 shows a schematic representation of the essential components of another device 100 according to the invention for the thermal treatment of solids 10 in plan view (top) and in side view (bottom). Shown is an electrode assembly 20 having two intermeshing comb structures, which are two-sided executed comb structures, in which the electrodes 22, 24 are located on both sides (in the figure, above and below) of the respective webs 26, 28. As shown, the electrodes 22, 24 extend along a common main axis X, wherein, in this embodiment as well, the webs 26, 28 each extend parallel to the main axis X. The electrodes 22, 24 of the electrode structure 20 are arranged perpendicular to the main axis X, the length of the electrodes varying along the electrode structure. It should be emphasized that in the arrangement after Fig. 3 the webs are arranged above the electrode structure and not in a plane therewith. In this case, they practically do not act as electrodes with respect to the structure 10 to be heated. The length of the electrodes 22, 24 along the electrode structure 20 varies linearly. In particular, the electrode arrangement 20 has a maximum electrode length in the middle of the electrode structure 20. The length of the electrodes 22, 24 adjacent thereto on both sides decreases linearly towards the outer end of the electrode structure 20. It can be seen from the plan view that the shield 40 has a square cross-section with respect to the plan view in the exemplary embodiment shown. The electrode assembly 20 is enclosed diagonally in the base of this square. As a rule, the square follows the position of the shield 40. A translatory movement according to the invention of the electrode arrangement 20 shown is preferably along the sides of the square shield 40, therefore in the embodiment shown in the arrangement shown, an angle of 45 ° to the edges of the shield 40 before.

FIG. 4 shows a schematic representation of different configurations of the cross section of the electrodes 22, 24. The individual electrodes 22, 24 of the electrode assembly 20 have on its underside, ie on the surface A of the solid 10 facing surface B, each having an edge region, which by a Edges K is marked. To influence the field line course during operation of the device 100 according to the invention, the shape of this edge region, in particular that of the edges K, in contrast to a rectangular or angular configuration (left), by rounding (right) or bevel (center) to be modified. To protect at least the surface B of the contacts 22, 24 and / or the surface A of the structure 10 to be treated, the contacts 22, 24 may also be provided with a protective layer 60. The protective layer 60 may, for example, the entire contact 22, 24, only individual contact points or only the surface B of Contacts 22, 24 include. The latter is illustrated for illustrative purposes in the illustrated embodiment of a contact 22, 24 with rounded edges K (right). All of these embodiments may also have a perforation that allows the removal of substances from the solid structure 10 to be treated and / or the ventilation of the surface A of the solid state structure 10.

Embodiment 1 Modeling the spatial distribution of the energy input into the treated structure

Among the many possible variations in the application, an example is illustrated in which parallel electrodes or electrode parts with alternating polarity ("hot", ie live, and "cold", ie grounded, electrodes) are used for heating. Over the electrodes a shield is arranged, which also extends over the adjacent surface. The "cold" electrodes are electrically connected to the grounded shielding and the Matchboxgehäuse, while the "hot" electrodes are electrically connected via a copper tape with the electronic matching network or with the voltage source for contacting. The arrangement for a vertical treatment (for example, a fragment of wall paneling) is shown schematically in FIG Fig. 5 shown.

FIG. 5 shows schematic representations of an application of the device according to the invention with a surface-bound binary electrode arrangement using the example of a wall to be heated. It shows Fig. 5a the shield with underneath, invisible comb structure and Fig. 5b a section through the device according to the invention with visible comb structure.

If one assumes for a simulation that the electrodes have a width of 20 mm and the distance between the electrode centers is 25 mm in each case, the result is a gap width between the electrodes of 5 mm. In the direction of the wall surface, the electrodes were beveled 5 mm at an angle of 45 ° so that there was an effective electrode gap of 15 mm on the surface, which is also decisive for the field distribution in the material. Utilizing realistic assumptions of material thermal propagation, heat transfer between material surface and air, and using the dielectric and physical parameters for the wood material, the temperature distributions for a 50 mm thick wood component were determined after certain periods of dielectric energy input.

Four different scenarios were compared: a conventional heating with a hot plate, a dielectric heating using the device according to the invention by means of radio-wave energy and the use of both methods in pulsed mode (1 min heating, 2 min break). In all cases, a power of 1 kW was used.

FIG. 6 shows temperature profiles for four different treatment regimes using the example of the solid wood. Shown are the four resulting temperature profiles after every 3 min, 6 min, 9 min and 15 min. (A) the temperature profile in continuous conventional RF heating, (c) the temperature profile in radio wave heating in pulsed mode (1 min power turned on, then each 2 min break) and (d) the temperature profile during conventional heating in pulsed mode (times as before).

It becomes clear that in the case of the radio-wave method, the maximum of warming as well as the total energy input are shifted significantly into the volume of the material. For a non-thermally insulated surface, the surface temperature can be lowered from the target volume to be achieved in volume, for example, so as not to damage sensitive coatings. The degree of temperature reduction can be varied by the choice of the insulating surface covering or the adjustment of the heat removal from the surface, for example by a cooling air flow. The conventional heating by means of hotplate (analogous results would be achieved with the hot air and the IR treatment), however, leads to a high surface temperature, to a pronounced decrease in temperature with the depth and to a much lower heating rate in the volume. Reducing the surface temperature to protect sensitive surfaces would further reduce the already slower rate of heating of the volume.

For practical application, the situation usually arises that a certain maximum temperature may not be exceeded, but a minimum temperature (eg the lethal temperature for pest control) must be achieved.

FIG. 7 shows a temperature depth profile for the four treatment regimes Fig. 6 , The four methods already mentioned are compared for a situation in which the maximum temperature is limited to 100 ° C. The time at which the limit temperature of 100 ° C was reached for the first time at one location is shown. Because the In accordance with the target temperature of 60 ° C., the penetration depths up to which this temperature was reached are also marked.

Once again, the clear advantages of the radio wave method using the device according to the invention and the method according to the invention at a power of 1 kW used (continuously or in the pulses in pulsed operation) again show. The penetration depths for the radio wave heating (13 mm or 17 mm, based on reaching the lethal temperature of 60 ° C) were significantly higher than that achieved in a conventional heating by means of hot plate (or analogously with the hot air or infrared method) (5 mm and 8 mm for continuous or pulsed operation). The required treatment times were comparable. This means at the same time that for the same penetration depths significantly longer treatment times would be necessary for the conventional heating, if in a certain volume, the target temperature is to be consistently achieved. It should be noted that in the case described there was no movement of the device over the surface to be treated. For a mobile application, the effective dwell time of the system at the position would need to be considered.

Embodiment 2: Heating a parquet surface with a double comb structure

For demonstration purposes, a wooden plate with a thickness of 20 mm using the in Fig. 8 heated double comb structure shown. For the electrodes 22, 24 and the webs 26, 28, structural elements made of steel were used in these orienting experiments. The distance between the electrodes 22, 24 was between 20 mm and 25 mm.

An HF generator (operating frequency 13.56 MHz, maximum power 3 kW) and an electronic matching network (maximum HF voltage 4 kV) were used.

The surface temperature was measured by means of an IR camera. At a depth of 10 mm below the wood surface, fiber optic temperature sensors were positioned to provide continuous temperature sensing during RW treatment. The positions of the sensors relative to the electrode structure (marked with x) are also Fig. 8 refer to.

FIG. 9 shows the time course of the temperatures in 10 mm depth when using the in Fig. 8 shown inventive device and using the inventive method. These are the results of a typical heating experiment using the inventive arrangement. It could be proven that a preselected minimum temperature of 60 ° C at a depth of 10 cm in the wood panel was reached everywhere. A maximum temperature of 100 ° C was not exceeded. The surface temperatures were significantly lower, as shown by IR camera imaging. Here, an average temperature of about 75 ° C at a maximum surface temperature of 82 ° C was observed.

It can be assumed that an even better homogeneity of the temperature distribution can be achieved by optimizing the electrode structure and by means of special experimental regimes (see Example 1).

The special experimental regimes represent the process according to the invention which, by virtue of its flexibility, allows a successful treatment of very different practical situations.

LIST OF REFERENCE NUMBERS

10

solid fuel

20

electrode assembly

22a, 22b,

first electrodes

24a, 24b,

second electrodes

26

first jetty

28

second bridge

30

High-frequency voltage source

40

shielding

42

holder

50

matching

60

protective layer

A

Surface of the solid 10

B

Surfaces of the electrode assembly 20

K

Edges of the electrodes 22, 24

X

Main axis of the electrode assembly 20

Claims (15)

A device (100) for the thermal treatment of solids (10), comprising a binary electrode arrangement (20) which can be arranged on a surface (A) of a solid (10), each having at least two electrodes (22, 24) electrically insulated from one another, wherein the electrode arrangement ( 20) comprises two interdigitated comb structures, and the electrode assembly (20) is electrically conductively connected to a radio frequency voltage source (30) adapted to apply to the electrode assembly (20) a radio frequency voltage having a frequency between 100 kHz and 50 MHz to create,
characterized in that
a holding device (42) is provided, designed to allow a translational movement of the electrode assembly (20) along the surface (A) of a solid (10). The apparatus (100) of claim 1, wherein the apparatus (100) comprises a surface (B) which is locatable on the surface (A) of the solid (10), the edges facing the surface (A) of the solid (10) (K) of the surface (B) are rounded or bevelled and / or the surface (B) is at least partially protected by a protective layer (60). Device (100) according to one of the preceding claims, wherein the electrode assembly (20) is perforated at least in partial areas and / or at least partially surrounded by an electrically conductive shield (26). Apparatus (100) according to any one of the preceding claims, wherein each of the comb structures comprises a web (26, 28) over which the respective electrodes (22, 22a, 22b, 22c, 22d, 22e, 22f, 24, 24a, 24b, 24c , 24d, 24e, 24f) of the electrode assembly (20) are electrically connected to each other, wherein the webs (26, 28) parallel to a major axis (X) of the electrode assembly (20) and wherein the electrodes (22, 22a, 22b, 22c , 22d, 22f, 24, 24a, 24b, 24c, 24d, 24e, 24f) are arranged perpendicular to the major axis (X) and the length of the electrodes (22, 24) varies along the electrode assembly (20). Device (100) according to one of the preceding claims, further comprising a means for translational movement of the electrode assembly (20). Device (100) according to one of the preceding claims, further comprising a regulating device for controlling the surface temperature of the solid (10). Device (100) according to one of the preceding claims, wherein the device (100) comprises an adsorbent for receiving the substances emerging from the solid. The device (100) of claim 7, wherein the adsorbent directly contacts at least one of the electrodes (22, 24). Device (100) according to one of the preceding claims, wherein the electrode assembly (20) has at least one perforation, which is designed to guide an air flow for cooling. Process for the thermal treatment of solids (10), comprising the following process steps: - Providing a device (100) for the thermal treatment of solids (10) according to one of claims 1 to 9, wherein the electrode assembly (20) on a surface (A) of a solid (10) is arranged, and - Applying a high-frequency voltage having a frequency between 100 kHz and 50 MHz to the electrode assembly (20), wherein an alternating electric field in the solid (10) is generated and by this alternating field heating of the solid (10). Method according to claim 10, wherein the surface temperature and / or the volume temperature of the solid (10) are regulated by a regulating device (70). The method of claim 11, wherein by means of the control device (70) by means of at least one means for cooling the surface (A) of the solid (10) at least partially cooling of the surface (A) of the solid (10). Method according to one of the preceding claims 10 to 12, wherein the electrode assembly (20) along the surface (A) of the solid (10) is generally translationally moved or the translational movement is not parallel to edges of the electrode assembly (20). Method according to one of the preceding claims 10 to 13, wherein the emerging from the treated structure of the solid (10) substances are bound to an adsorbent material. Method according to one of the preceding claims 10 to 14, wherein a cooling of the surface of the solid takes place via an air flow, wherein the air flow is preferably guided via perforations in the electrodes (22, 24) of the electrode assembly (20).

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