System for drying of dielectric products

Abstract

System (1) for drying of dielectric products (99) comprising: a first array (10) of first electrodes (100), wherein the first array (10) is arranged along a first plane (P1), which extends along a first direction (L1) and a second direction (L2), a second array (20) of second electrodes (200), wherein the second array (20) is arranged along a second plane (P2), which extends along the first direction (L1) and the second direction (L2), and wherein the first plane (P1) is spaced apart from the second plane (P2) along a third direction (L3), and wherein each of the first electrodes (100) is spaced apart from its corresponding second electrode (200) along the third direction (L3), forming a plurality of pairs (300) of the first electrode (100) and the second electrode (200). The system (1) further comprises a plurality of radio-frequency generators (30) adapted to produce radio frequency signals of specific and adjustable amplitude and preselected frequency, wherein each of the plurality of radio-frequency generators (30) is electrically coupled to one pair (300) of the first electrode (100) and the second electrode (200).

Description

[0001] P2023,1498 WO N / P230150WO01 October 29, 2024 - 1 - Description SYSTEM FOR DRYING OF DIELECTRIC PRODUCTS The present disclosure relates to a system for drying dielectric products. Radio Frequency (RF) heating and drying systems utilize electromagnetic energy to rapidly heat and dry many types of bulk materials, such as dielectric materials, as well as finished products, with excellent speed and efficiency. They require only a fraction of the floorspace of conventional heating technologies, produce no greenhouse gasses, do not require high process temperatures, and provide excellent control of final moisture content and uniformity. High- frequency electric fields can create standing waves in electrodes, resulting in high potentials at certain points and zero potential at some other points. As a result, the electric field strength between electrodes will be different across the electrodes extension, leading to spatially non- uniform heat generation in the object being heated. This can create hotspots in the dielectric product during production. US 2003 / 205571 A1 discloses how a food product is heated by maintaining the food product in an AC electrical field generated by an RF signal. As the heating takes place, maximum energy is delivered to the food product using automatic impedance matching to adjust the rate of the process. WO 2023 / 229195 A1 describes a dielectric heating device comprising at least one power source; a load circuit including a plurality of electrodes and at least one P2023,1498 WO N / P230150WO01 October 29, 2024 - 2 - inductor; and at least one driving circuit configured to output alternating-current power to the load circuit by using power provided from the at least one power source. The plurality of electrodes may include a plurality of top electrodes arranged in substantially the same plane, and one or more bottom electrode arranged in a plane parallel to the plane formed by the plurality of top electrodes. US 4104 804 A describes a method to dry explosive materials such as gun powder and rocket propellants by supplying the material in particulate form to a drying zone, passing the particulate material through the drying zone while agitating the material to cause the particles to move in random fashion, subjecting the particulate material to electromagnetic radiation to heat the moisture contained within the particles, maintaining a relatively cool gaseous atmosphere in the drying zone, and recovering the particulate material from the drying zone with the particles having a reduced moisture content and a temperature which is low as compared to the ignition temperature of the particles. AU 2022229 770 A1 discloses a dielectrically heated aerosol- generating system comprising an aerosol-forming substrate, a plurality of pairs of electrodes, and an aerosol-generating device. Each pair of electrodes comprises a first electrode spaced apart from a second electrode. The aerosol-generating device comprises a controller configured to connect to each pair of electrodes. Each pair of electrodes forms a capacitor with a portion of the aerosol-forming substrate. The controller is configured to supply an alternating voltage to the plurality of pairs of electrodes for dielectrically heating the aerosol-forming substrate. P2023,1498 WO N / P230150WO01 October 29, 2024 - 3 - It is an object to provide a system for drying dielectric products of any size, while increasing the uniformity of the spatial distribution of heat generation and maintaining an efficient heating rate. This object is solved by the features of the independent claims. Advantageous embodiments are indicated in the dependent claims. Embodiments of the disclosure, for instance as claimed in the independent claim, address the above shortcomings in the art in whole or in part. Further embodiments of the system for drying of dielectric products are subject matter of the further claims. There is provided a system for drying of dielectric products comprising, a first array of first electrodes, wherein the first array is arranged along a first plane, which extends along a first direction and a second direction. Furthermore, the system comprises a second array of second electrodes, wherein the second array is arranged along a second plane, which extends along the first direction and the second direction. The first plane is spaced apart from the second plane along a third direction. Each of the first electrodes is spaced apart from its corresponding second electrode along the third direction, forming a plurality of pairs of the first electrode and the second electrode each. Furthermore, the system comprises a plurality of radio-frequency generators adapted to produce radio frequency signals of specific and adjustable amplitude and preselected frequency, wherein each of the plurality of radio-frequency generators is electrically coupled to one pair of the first electrode and second electrode. P2023,1498 WO N / P230150WO01 October 29, 2024 - 4 - In its basic configuration, the system comprises two or more appropriately shaped first electrodes and two or more appropriately shaped second electrodes, which define a treatment area in which the dielectric product to be heated is positioned or through which it passes. The first array comprises a plurality of first electrodes. The first array is arranged along a first plane, which extends along a first direction and a second direction. The first array is for example arranged in the first plane. The first array comprises at least two first electrodes. The first electrodes are arranged along the first plane and extend substantially in the first plane. The first electrodes comprise each a first main surface extending along the first plane and a second main surface extending along the first plane. The first and second planes can be planar surfaces but are not limited to planar surfaces. The first and second planes can also be curved surfaces along which the arrays are arranged. The first, second and third directions can be straight lines, like in a cartesian coordinate system, but they are not limited to straight lines. The first, second and third directions can also be curved lines. Therefore, the electrodes can be arranged along these curved surfaces, which are formed by the first and second planes. Furthermore, the electrodes can be shaped, such that they extend along curved lines, which are formed by the first and second directions. For example, the electrodes are bend along their lateral extensions. P2023,1498 WO N / P230150WO01 October 29, 2024 - 5 - The second array comprises a plurality of second electrodes. The second array is arranged along a second plane, which extends along a first direction and a second direction. The second array is for example arranged in the second plane. The second array comprises at least two second electrodes. The second electrodes are arranged along the second plane and extend substantially in the second plane. The second electrodes comprise each a third main surface extending along the second plane and a fourth main surface extending along the second plane. The first, second, third and fourth main surfaces each have a greater extension than the side surfaces of the first electrodes and the second electrodes that are aligned transversely to them. The first electrodes and the second electrodes are arranged in such a way, that the second main surfaces face the third main surfaces. The first electrodes are for example arranged side by side in the first plane. The second electrodes are for example arranged side by side in the second plane. The first plane is spaced apart from the second plane along a third direction. The third direction is perpendicular to the first plane defined by the first and second directions. The first plane and the second plane are for example parallel to each other. Alternatively, the distance along the third direction between the first plane and the second plane is variable. In this case, the planes are inclined towards each other. Each of the first electrodes is spaced apart from its corresponding second electrode along the third direction, forming a plurality of pairs of the first electrode and the second electrode each. In this context a corresponding electrode is for example defined by a first electrode, which P2023,1498 WO N / P230150WO01 October 29, 2024 - 6 - is spaced apart from a second electrode by the shortest distance possible along the third direction. The same definition applies for a second electrode, which is spaced apart from a first electrode by the shortest distance possible along the third direction. Each first electrode has a second electrode as a counterpart. For example, when the system comprises three first electrodes, the system comprises also three second electrodes, forming three pairs. One pair consists of one first electrode and one second electrode. Alternatively, or additionally, the distance along the third direction between the first electrodes and the second electrodes is variable across different electrode pairs. Alternatively, or additionally, the distance along the third direction between the first electrode and the second electrode within an electrode pair is variable. In this case, the electrodes can be inclined towards each other. This facilitates generating varying degrees of heat between the electrodes. The system is not limited to one, two or three pairs of first electrode and second electrode. The system comprises a plurality of pairs, for example four pairs, five pairs, ten pairs or twenty pairs or more, depending on the size of the dielectric product to be dried. Furthermore, the system comprises a plurality of radio- frequency generators. Each of the plurality of radio- frequency generators is electrically coupled to one pair of the first electrode and second electrode. Therefore, for each pair of electrodes, there is provided one radio-frequency generator. The radio-frequency generator is adapted to produce radio frequency signals of specific and adjustable amplitude and predefined frequency. The frequency of the signal remains the same during operation of the system. P2023,1498 WO N / P230150WO01 October 29, 2024 - 7 - When high frequency electrical excitations are used, they create an electric field between the electrodes, resulting in heat generation in the dielectric product therein. The structure of the polar water molecule H2O is the basis for the thermal response of water when subjected to an RF electric field. In a radio frequency heating system, the radio-frequency generator creates an alternating electric field between the first electrode and the second electrode. This causes the water molecules to rotate. The constant rotation causes friction and heat to rapidly develop. The wave nature of electric field becomes significant when electrode sizes are comparable to the wavelength, resulting in spatially nonuniform electric field. Using an array of a plurality of electrodes on the same plane mitigates this effect and leads to a more uniform electric field even for larger dielectric products to be dried. Thus, the dimensions of the dried dielectric product are not limited by the used excitation frequency. For a dielectric product with a large extension, more electrodes are used to cover the whole area of the dielectric product. The generated heat is distributed more uniformly, which leads to an improved drying process. According to a further embodiment, the first electrode and the second electrode of each pair are arranged parallel to each other. Each of the first electrode and second electrode pairs basically form a plate capacitor. Between the electrodes the electric field is generated. According to a further embodiment the plurality of radio- frequency generators is interconnected by a phase harmonizing P2023,1498 WO N / P230150WO01 October 29, 2024 - 8 - system to ensure the plurality of radio-frequency generators operates in phase harmony. One important aspect is to ensure a uniform electric field to obtain a uniform heat distribution in the dielectric product. For this purpose, all the radio-frequency generators produce each a radio frequency signal with the same frequency. The same frequency includes frequencies, which are substantially the same within tolerances. The phase harmonizing system enables coupling of a plurality of radio-frequency generators in such a way that harmonization of the frequencies for each radio-frequency generator is improved. According to a further embodiment the value range of the frequency of the produced radio frequency signal is in the range from 1 MHz to 100 MHz. The radio frequency signal has a frequency in the value range between 1 MHz and 100 MHz. According to a further embodiment the greatest dimension of the first electrodes in the first plane and the greatest dimension of the second electrodes in the second plane are each smaller than 30% of the wavelength of the specific radio frequency signal. The greatest dimension of one electrode is for example the diagonal in case of a square or rectangular shape or the diameter in case of circular electrodes. By limiting the size of the electrode along the first plane, a more uniform electric field is generated between the electrodes. P2023,1498 WO N / P230150WO01 October 29, 2024 - 9 - For example, using a 27.12 MHz excitation, the associated wavelength is approximately 11 meters in vacuum or air. This means that high and zero electric fields are physically separated by 2.75 meters. Hence, if the dimensions of each electrode are 3.3 m times 3.3 m, the electric field will be reasonably uniform. In this context a reasonably uniform electric field is an electric field, whose field strength is at a maximum at the center of the electrodes and the field strength at the periphery of the electrodes is at least 90% of the maximum electric field strength. According to a further embodiment directly adjacent first electrodes of the first array are spaced apart in the first plane by at least a first distance and directly adjacent second electrodes of the second array are spaced apart in the second plane by at least a second distance. The first distance and the second distance have approximately the same size, but they can also differ from each other. Each of the first electrodes are spaced apart by at least the first distance and each of the second electrodes are spaced apart by at least the second distance and the second distance, thus the electrodes are far enough spaced apart to avoid short-circuits or electric sparks to pass between the first electrodes and between the second electrodes, respectively. The first electrodes are for example spaced apart by the first distance along the first direction and spaced apart along the second direction by a distance greater than the first distance. The different distances between the first electrodes along the first plane facilitate a flexible arrangement of the electrodes and mitigate for example tolerances of the electrode areas. The second electrodes are for example spaced apart by the second distance along the P2023,1498 WO N / P230150WO01 October 29, 2024 - 10 - first direction and spaced apart along the second direction by a distance greater than the second distance. The different distances between the second electrodes along the second plane, facilitate a flexible arrangement of the electrodes and mitigate for example tolerances of the electrode areas. According to a further embodiment the space between adjacent first electrodes in the first plane and the space between adjacent second electrodes in the second plane are filled with an insulating material. The insulating material further improves avoiding electric sparks to pass between the first electrodes and between the second electrodes. According to a further embodiment the electrodes have a square shape, which extends along the first direction and the second direction. The electrodes are not limited to square shapes. The electrodes can have also circular shapes or polygonal shapes, like rectangular, triangular, trapezoidal or others. Preferably symmetric shapes are used for producing more uniform electric fields. Alternatively, or additionally the electrodes are arranged in the arrays along a curved first and / or second plane. The combination of differently shaped electrodes can be used to cover the surface of the dielectric product, which can have any shape with non-uniform thickness along the first, second and / or third direction. Thus, the system is adapted to dry dielectric products with curved surfaces and / or products with varying thickness along the first, second and / or third direction. P2023,1498 WO N / P230150WO01 October 29, 2024 - 11 - According to a further embodiment the electrodes are arranged in a N-by-M grid, which extends along the first direction and the second direction. N and M are natural numbers, wherein N starts from 1 and M starts from 2. N and M must not be different and can have the same numerical value. For example, for drying a 2 m times 3 m dielectric product, like a pressboard, extending along the first direction and the second direction, a plurality of electrodes is used to cover the entire area of the dielectric product. This results in spatial uniformity in the electric field, resulting in highly uniform heat generation in the dielectric product, like a cellulose block. In this example 7 pairs of square shaped electrodes, 0.3 m times 0.3 m large, are used, which are arranged along the first direction and 10 pairs of square shaped electrodes, 0.3 m times 0.3 m large, are used, which are arranged along the second direction. With this 7 by 10 grid the 2 m times 3 m large area of the dielectric product is covered by 70 electrodes on each side. Hence, it is possible to dry dielectric products which extend along the first direction and / or the second direction beyond the boundaries of the electrodes. In this manner a dielectric product can be dried, whose surface area is larger than the surface area of a single electrode. According to a further embodiment the first electrodes and the second electrodes comprise recesses for releasing moisture from the dielectric product. P2023,1498 WO N / P230150WO01 October 29, 2024 - 12 - According to a further embodiment the greatest dimension of the recesses is smaller than 1% of the wavelength of the specific radio frequency signal. The recesses improve the drying capabilities of the system. The recesses can be of circular shape, square shape, or any other polygonal shape. The greatest dimension of a recess is for example the diameter in case of circular recesses or the diagonal in case of a square or rectangular shape. To avoid disturbances of the electrical field, which would lead to a more non-uniform electrical field and thus to a more non-uniform heat generation, the dimensions of the recesses should not excess an upper threshold with respect to the wavelength. Furthermore, the recesses should be sufficiently large to enable water vapor or moisture to pass through. Furthermore, sharp edges at the periphery of the electrodes should be avoided. The edges at the periphery of the electrodes are therefore rounded. Alternatively, or additionally the edges of the recesses are rounded. According to a further embodiment the system comprises an additional prevention layer for preventing short-circuits, wherein the additional prevention layer is arranged between the first electrodes and the dielectric product and / or between the second electrodes and the dielectric product along the third direction. The system comprises for example a plurality of prevention layers, which are arranged at each individual first electrode and / or each individual second electrode. For example, the P2023,1498 WO N / P230150WO01 October 29, 2024 - 13 - prevention layer is divided into individual segments, which are assigned to each electrode. The individual segments of the prevention layer can also be assigned to specific electrodes. For example, the individual segments are attached to the electrodes located in the center area of the array, leaving out the electrodes, which are located at the peripheral area of the array. Alternatively, or additionally the individual segments are attached to only some of the electrodes, like only to every second or third or fourth electrode. Alternatively, the prevention layer may be a continuous layer extending across all the first electrodes and / or the second electrodes. Therefore, only one prevention layer is used for the first array of first electrodes and / or one prevention layer is used for the second array of second electrodes. The additional prevention layer separates the first electrode and / or the second electrode physically from the dielectric product. The separation improves the electrical insulation between the electrodes and the dielectric product. Additionally, or alternatively, the prevention layer comprises for example some moisture absorbing material to improve the drainage of the liquid inside the dielectric product. Furthermore, the prevention layer may help to protect the surfaces of the electrodes from irregularities of the dielectric product. While the disclosure is amenable to various modifications and alternative forms, specifics thereof are shown by way of example in the figures and will be described in detail. It should be understood, however, that the intention is not to P2023,1498 WO N / P230150WO01 October 29, 2024 - 14 - limit the disclosure to the particular described embodiments and examples. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure defined by the appended claims. The accompanying figures are included to provide a further understanding. In the figures, elements of the same structure and / or functionality may be referenced by the same reference signs. It is to be understood that the embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale. Figure 1 is a perspective view of a system for drying dielectric products according to an embodiment, Figure 2 is a perspective view of a system for drying dielectric products according to a further embodiment, Figure 3 is a perspective view of a system for drying dielectric products according to a further embodiment, Figure 4 is a top view of a system for drying dielectric products according to an embodiment. Figure 1 shows a system 1 for drying of dielectric products 99 comprising. The system 1 comprises a first array 10 of first electrodes 100. The first array 10 is arranged along a first plane P1, which extends along a first direction L1 and a second direction L2. The system 1 further comprises a second array 20 of second electrodes 200. The second array 20 is arranged along a second plane P2, which extends along the first direction L1 and the second direction L2. The first plane P1 is spaced apart from the second plane P2 along a third direction L3. The third direction L3 is perpendicular to the first plane P1 and the second plane P2 defined by the P2023,1498 WO N / P230150WO01 October 29, 2024 - 15 - first L1 and second directions L2. Each of the first electrodes 100 is spaced apart from its corresponding second electrode 200 along the third direction L3, forming a plurality of pairs 300 of the first electrode 100 and the second electrode 200. In Figure 1 two first electrodes 100 and two second electrodes 200 are shown. The electrodes 100, 200 form two pairs 300 in this case. Directly adjacent first electrodes 100 are spaced apart in the first plane P1 by a first distance d1 and directly adjacent second electrodes 200 of are spaced apart in the second plane P2 by a second distance d2. The first electrodes 100 are for arranged side by side in the first plane P1 and the second electrodes 200 are arranged side by side in the second plane. The first distance d1 and the second distance d2 have approximately the same size, but they can also differ from each other. Each of the first electrodes 100 and each of the second electrodes 200 is far enough spaced apart from the adjacent electrode 100, 200 to avoid short-circuits or electric sparks to pass between the first electrodes 100 and between the second electrodes 200. The space between two first electrodes 100 along the first plane P1 and the space between two second electrodes 200 along the second plane P2 is filled with an insulating material 50 to further improve avoiding electric sparks to pass between the first electrodes 100 and between the second electrodes 200. The insulating material 50 can optionally be left out, if the first distance d1 and the second distance d2 are large enough to prevent electric sparks to pass between the first electrodes 100 or between the second electrodes 200. Alternatively, or additionally, the first electrodes 100 are for example spaced apart by the first distance d1 along the first direction L1 and spaced apart along the second P2023,1498 WO N / P230150WO01 October 29, 2024 - 16 - direction L2 by a distance greater than the first distance d1. The different distances between the first electrodes 100 along the first plane P1 facilitate a flexible arrangement of the electrodes and mitigate for example tolerances of the electrode areas. The second electrodes 200 are for example spaced apart by the second distance d2 along the first direction L1 and spaced apart along the second direction L2 by a distance greater than the second distance. The different distances between the second electrodes 200 along the second plane P2, facilitate a flexible arrangement of the electrodes and mitigate for example tolerances of the electrode areas. The system 1 comprises for example two or more appropriately shaped first electrodes 100 and two or more appropriately shaped second electrodes 200, which define a treatment area in which the dielectric product 99 to be heated is positioned or through which it passes. The first electrodes 100 are facing the second electrodes 200. The dielectric product 99 is placed between the electrodes 100, 200. The dielectric product 99 is for example a cellulose block, a pressboard, or any other material, which has to be dried. The dielectric product 99 can have any shape, like cuboid, trapezoidal, wedged, cylindrical or parallelepiped shaped. The thickness of the dielectric product 99 can vary across the first direction l1 and / or the second direction L2 and / or across the third direction L3. The system further comprises a plurality of radio-frequency generators 30 adapted to produce radio frequency signals of specific and adjustable amplitude and frequency. Each of the plurality of radio-frequency generators 30 is electrically coupled to one pair 300 of the first electrode 100 and the second electrode 200. In Figure 1 two of radio-frequency P2023,1498 WO N / P230150WO01 October 29, 2024 - 17 - generators 30 are shown corresponding to the number of pairs. The system 1 is not limited to just two pairs 300 of electrodes 100, 200 and can comprise any number of pairs 300. The system 1 comprises for example three, four, five, ten or twenty or more pairs 300, depending on the size of the dielectric product 99 to be dried. Therefore, for each pair 300 of electrodes, there is provided one radio-frequency generator 30 and the system 1 comprises three, four, five, ten or twenty or more radio-frequency generators 30, depending on the number of pairs 300. The radio-frequency generator 30 is adapted to produce radio frequency signals of specific and adjustable amplitude and predefined frequency. The frequency of the produced frequency signal remains the same during operation of the system 1. The radio-frequency generators 30 are interconnected by a phase harmonizing system 35 to ensure the radio-frequency generators 30 operate in harmony. The frequency of the radio-frequency generators 30 is approximately the same for each radio-frequency generator 30. The frequencies can differ from each other by known tolerances. The radio frequency signal has a frequency in the value range between 1 MHz and 100 MHz. Figure 2 shows a perspective view of the system 1 for drying of dielectric products 99. The system 1 is basically the same as shown in Figure 1 with the difference, that the first electrodes 100 and the second electrodes 200 comprise recesses 40 for releasing moisture from the dielectric product 99. The recesses 40 improve the drying capabilities of the system 1. The recesses 40 can be of circular shape, square shape, or any other polygonal shape. The greatest dimension of a recess 40 is for example the diameter in case of circular recesses 40 or the diagonal in case of a square or rectangular shape. The greatest dimension of the recesses P2023,1498 WO N / P230150WO01 October 29, 2024 - 18 - 40 in the first plane P1 or in the second plane P2 is smaller than 1% of the wavelength of the specific radio frequency signal. To avoid disturbances of the electrical field between the electrodes 100, 200, which would lead to a more non- uniform electrical field and thus to a more non-uniform heat generation, the dimensions of the recesses 40 should not excess an upper threshold with respect to the wavelength. Optionally, sharp edges of the recesses 40 should be avoided. Thus, the edges of the recesses 40 should be rounded. Alternatively, or additionally the edges at the periphery of the electrodes 100, 200 are rounded. Furthermore, the recesses 40 should be sufficiently large to enable water vapor or moisture to pass through. Figure 3 shows a perspective view of the system 1 for drying of dielectric products 99. The system 1 is basically the same as shown in Figure 2 with the difference, that the system 1 comprises an additional prevention layer 60 for preventing for example short-circuits. The additional prevention layer 60 is arranged between the first electrodes 100 and the dielectric product 99 and / or between the second electrodes 200 and the dielectric product 99 along the third direction L3. The system 1 comprises for example a plurality of prevention layers 60, which are arranged at each individual first electrode 100 and / or each individual second electrode 200. For example, the prevention layer 60 is divided into individual segments, which are assigned to each electrode 100, 200. The individual segments of the prevention layer 60 can also be assigned to specific electrodes 100, 200. For example, the individual segments are attached to the electrodes 100, 200 located in the center area of the first and / or second array 10, 20, leaving out the electrodes 100, 200, which are located at the peripheral area of the first P2023,1498 WO N / P230150WO01 October 29, 2024 - 19 - and / or second array 10, 20. Alternatively, or additionally the individual segments are attached to only some of the electrodes 100, 200, like only to every second or third or fourth electrode 100, 200. Alternatively, or additionally, the prevention layer 60 may be a continuous layer extending across all the first electrodes 100 and / or the second electrodes 200. Therefore, only one prevention layer 60 is used for the first array 10 of first electrodes 100 and / or one prevention layer 60 is used for the second array 20 of second electrodes 200. The additional prevention layer 60 separates the first electrode 100 and / or the second electrode 200 physically from the dielectric product 99. The separation improves the electrical insulation between the electrodes 100, 200 and the dielectric product 99. Additionally, or alternatively, the prevention layer 60 comprises for example some moisture absorbing material to improve the drainage of the liquid inside the dielectric product 99. Furthermore, the prevention layer 60 may help to protect the main surfaces of the electrodes 100, 200 from irregularities of the dielectric product 99. Optionally, the recesses 40 are left out and only the prevention layer 60 is used in a further example. Figure 4 shows the system 1 from a top view when viewed along the third direction L3. Figure 4 shows the system 1 with the first array 10 comprising four first electrodes 100, which are arranged in a two-by-two grid in the first plane P1. Two first electrodes 100 are arranged side by side along the first direction L1 and two first electrodes 100 are arranged side by side along the second direction L2. The first electrodes 100 arranged along the first direction L1 are P2023,1498 WO N / P230150WO01 October 29, 2024 - 20 - spaced apart by the first distance d1. The first electrodes 100 arranged along the second direction L2 are spaced apart by the first distance d1. Alternatively, only the first electrodes 100 arranged along the first direction L1 are spaced apart by the distance d1 and the first electrodes arranged along the second direction L2 are spaced apart by a different distance greater than the first distance d1. In this case the different distances can compensate for tolerances in the dielectric material 50, which is located between two directly adjacent electrodes 100. The arrangement of the first electrodes 100 is not limited to a two-by-two grid. The electrodes 100 are arranged in a N-by- M grid, which extends along the first direction L1 and the second direction L2. N and M are natural numbers, wherein N starts from 1 and M starts from 2. N and M must not be different and can have the same numerical value. For example (not shown), for drying a dielectric product 99, like a pressboard, which is 2 m times 3 m large and extends along the first direction L1 and the second direction L2, a plurality of electrodes 100 is used to cover the entire area of the dielectric product 99. This results in spatial uniformity in the electric field, resulting in highly uniform heat generation in the dielectric product 99, like a cellulose block. In this theoretical example 7 pairs of square shaped electrodes, 0.3 m times 0.3 m large, are used, which are arranged along the first direction and 10 pairs of square shaped electrodes, 0.3 m times 0.3 m large, are used, which are arranged along the second direction. With this 7 by 10 grid the area of the dielectric product 99 is covered by 70 electrodes 100. Hence, it is possible to dry dielectric products 99, which extend along the first direction L1 and / or P2023,1498 WO N / P230150WO01 October 29, 2024 - 21 - the second direction L2 beyond the boundaries of the electrodes 100. In this manner a dielectric product 99 can be dried, whose surface area is larger than the surface area of a single electrode 100. In Figure 4 the electrodes 100 are square shaped. The electrodes 100 are not limited to square shapes. The electrodes 100 can have also circular shapes or polygonal shapes, like rectangular, triangular, trapezoidal or others. Preferably symmetric shapes are used for producing more uniform electric fields. The first electrodes 100 comprise recesses 40. Alternatively, the recesses 40 are left out and the first electrodes 100 do not comprise any recesses 40. The same reasoning also applies to the second array 20 with the second electrodes, which are not shown in Figure 4. The embodiments shown in the Figures 1 to 4 as stated represent exemplary embodiments of the System 1 for drying dielectric products 99. Therefore, they do not constitute a complete list of all embodiments according to the improved arrangement for the System 1 for drying dielectric products 99. Actual arrangements of the System 1 for drying dielectric products 99 may vary from the exemplary embodiments described above.

[0002] P2023,1498 WO N / P230150WO01 October 29, 2024 - 22 - Reference Signs 1 system 10 first array 100 first electrode 20 second array 200 second electrode 300 pair 30 radio-frequency generator 35 phase harmonizing system 40 recess 50 insulating material 60 prevention layer 99 dielectric product d1 first distance d2 second distance L1 first direction L2 second direction L3 third direction P1 first plane P2 second plane

Claims

P2023,1498 WO N / P230150WO01 October 29, 2024 - 23 - Claims 1. System (1) for drying of dielectric products (99) comprising: - a first array (10) of first electrodes (100), wherein − the first array (10) is arranged along a first plane (P1), which extends along a first direction (L1) and a second direction (L2), - a second array (20) of second electrodes (200), wherein − the second array (20) is arranged along a second plane (P2), which extends along the first direction (L1) and the second direction (L2), wherein − the first electrodes (100) and the second electrodes (200) comprise recesses (40) for releasing moisture from the dielectric product (99), and wherein − the first plane (P1) is spaced apart from the second plane (P2) along a third direction (L3), and wherein − each of the first electrodes (100) is spaced apart from its corresponding second electrode (200) along the third direction (L3), forming a plurality of pairs (300) of the first electrode (100) and the second electrode (200), and - a plurality of radio-frequency generators (30) adapted to produce radio frequency signals of specific and adjustable amplitude and preselected frequency, wherein each of the plurality of radio-frequency generators (30) is electrically coupled to one pair (300) of the first electrode (100) and the second electrode (200), wherein - the greatest dimension of the first electrodes (100) in the first plane (P1) and the greatest dimension of the second electrodes (200) in the second plane (P2) are each smaller than 30% of the wavelength of the specific radio frequency signal, and whereinP2023,1498 WO N / P230150WO01 October 29, 2024 - 24 - - the greatest dimension of the recesses (40) is smaller than 1% of the wavelength of the specific radio frequency signal.

2. System (1) according to claim 1, wherein the first electrode (100) and the second electrode (200) of each pair (300) are arranged parallel to each other.

3. System according to claim 1 or 2, wherein the plurality of radio-frequency generators (30) is interconnected by a phase harmonizing system (35) to ensure the plurality of radio- frequency generators (30) operates in phase harmony.

4. System (1) according to any of the preceding claims, wherein the value range of the frequency of the produced radio frequency signal is in the range from 1 MHz to 100 MHz.

5. System (1) according to any of the preceding claims, wherein directly adjacent first electrodes (100) of the first array (10) are spaced apart in the first plane (P1) by at least a first distance (d1) and directly adjacent second electrodes (200) of the second array (20) are spaced apart in the second plane (P2) by at least a second distance (d2).

6. System (1) according to any of the preceding claims, wherein the space between adjacent first electrodes (100) in the first plane (P1) and the space between adjacent second electrodes (200) in the second plane (P2) are filled with an insulating material (50).

7. System (1) according to any of the preceding claims, wherein the electrodes (100, 200) have a polygonal and / orP2023,1498 WO N / P230150WO01 October 29, 2024 - 25 - circular shape, which extends along the first direction (L1) and the second direction (L2).

8. System (1) according to any of the preceding claims, wherein the electrodes (100, 200) have a square and / or a rectangular and / or triangular shape, which extends along the first direction (L1) and the second direction (L2).

9. System (1) according to any of the preceding claims, wherein the electrodes (100, 200) are arranged in a N-by-M grid, which extends along the first direction (L1) and the second direction (L2).

10. System (1) according to any of the preceding claims, comprising an additional prevention layer (60) for preventing short-circuits and / or discharges, wherein the additional prevention layer (60) is arranged between the first electrodes (100) and the dielectric product (99) and / or between the second electrodes (200) and the dielectric product (99) along the third direction (L3).

11. System (1) according to claim 10, wherein the additional prevention layer (60) comprises electrically non-conducting and non-ferromagnetic material.

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