REGENERATIVE BURNER

Description

Regenerative burner *** DESCRIPTION Field of invention 5 The present invention relates to the field of heating furnaces (“heating furnace”) at high temperatures. In particular, the present invention concerns a regenerative burner that can be used, for example, for a steelworks furnace - forging, rolling, annealing or for heating - or for a waste incinerator furnace. 10 State of the art As is known, various types of furnaces are used in the steel industry. heating at high temperatures (henceforth simply “ovens”); for example, forging furnaces, rolling furnaces, annealing furnaces and reheating furnaces. In order to bring the products (sheets, metal pipes, 15 billets etc.) at the desired temperature, the ovens can be equipped with regenerative burners. According to the most common embodiment, regenerative burners they are arranged in series along the product handling plane in the oven, that is, the long mobile floor of the oven. The floor can also be 20 stationary. Regenerative burners have a structure that is symmetrical with respect to to a plane of symmetry orthogonal to the movement plane of the furnace; in In practice each regenerative burner can be divided into two parts: the first part, for example placed to the left of the symmetry plane, and a second 25 part, for example placed to the right of the symmetry plane. ‐ 2 ‐ The regenerative burner has a symmetrical structure because the second part is essentially the mirror copy of the first part (and vice versa). Figure 1 shows a schematic representation of a regenerative burner 100. according to the known technique and the symmetry plane α of the burner is also shown 5 regenerative 100. The moving floor of the furnace is also shown schematically 101 and the related furnace 102. The regenerative burner 100 has a first part 103, shown at left of the symmetry plane α, and a second part 104, shown to the right of the symmetry plane α: the first part 103 and the second part 104 are among themselves 10 mirror images with respect to the symmetry plane α. With reference to the first part 103 it is possible to observe that the burner regenerative 100 features a 105 line for the supply of combustion air, which for ease will be identified only as “air”, a corresponding valve 106 to open or close the air passage in line 105, a burner 107, a 15 line 108 for the exhaust of the fumes and a corresponding valve 109 to open or close the passage of fumes through line 108. As is known, in corresponding to the burner 107 there is an element made of ceramic material, and for this reason identified in the sector as a ceramic element or as a ceramic mass. In figure 1, the ceramic element is 20 identified with the reference 110. The ceramic element 110 can be positioned in a collector duct upstream of burner 107. For example, the ceramic element 110 can be made in one of the following materials: mullite, alumina, cordierite, high-strength refractories to thermal shocks and alloyed with elements with high thermal conductivity. 25 The second part 104 has the same components as the first part - 3 - 103; in particular it includes: a line 111 for the supply of air, a corresponding valve 112, a burner 113, a line 114 for the exhaust of the fumes, a corresponding valve 115 and a ceramic element 116 housed in burner correspondence 113. 5 As is known, the symmetrical structure of the regenerative burner 100 allows burners 107 and 113 to operate alternately: when one one is on, the other is off, and vice versa. In practice, an operating cycle of the regenerative burner comprises a first phase in which the burner 107 is on and burner 113 is off and a second phase in which burner 107 is 10 off and burner 113 is on. These cycles are repeated throughout the service life of the steelworks. Therefore, lines 105 and 111 for air supply and lines 108 and 114 for the flue gas exhausts are opened and closed by the corresponding valves in such a way alternate. 15 For example, figure 1 shows the phase in which burner 107 is lit. and burner 113 is off: the arrows in figure 1 indicate the path of air and fumes. Air enters burner 107 through line 105 (valve 106 is open) and the line 108 for the exhaust of the fumes is closed by the relative valve 109. 20 The air is used in the combustion carried out by the burner 107 and the fumes generated by burner 107 pass through burner 113 (off) and are discharged through flue gas line 114 (valve 115 is open), line 111 for the air supply being closed by the relative valve 112. After this first phase, burner 107 switches off and the 25 burner 113. As a result, line 105 for the air supply is closed ‐ 4 ‐ from the relative valve 106 and instead the line 111 is opened for the supply of air to burner 113. Correspondingly, line 108 for the exhaust of flue gases is opened and the 114 line for the exhaust fumes is closed by the relative valve 115. 5 Once the activity of burner 113 is finished, the cycle is repeated. The 100 regenerative burner allows you to save energy right thanks to the alternating operation of burner 107 and burner 113; in fact, when burner 107 is lit, the fumes produced by this burner pass through the burner 113 and the related ceramic element 116. Since these 10 fumes are hot they heat the ceramic element 116. When burner 107 goes out and burner 113 comes on, the air coming from line 111 to feed burner 113 passes through the ceramic element 116; passing through the ceramic element 116 the air heats up and is therefore used by the pre-heated burner 113. 15 In this way the burner 113 has to use less energy to heat the product present in the furnace 102. When the burner 113 is turned on, the fumes cause the ceramic element 110 to heat up which will give off heat to the air supplied by line 105 when burner 107 is turned on. 20 Generally each burner 107, 113 remains lit for an interval of time between 20 seconds and 100 seconds, which corresponds to the time necessary to heat the ceramic element of the switched off burner. As is known, if on the one hand the ceramic elements 110, 116 allow for reduce the energy used by burners 107, 113, the very presence of the 25 ceramic elements 110, 116 represents a criticality for the functioning and ‐ 5 ‐ maintenance of regenerative burners. This is also officially recognized in the document “Best Available Techniques (BAT) Reference Document for the Ferrous Metals Processing Industry” (Industrial Emissions Directive 2010 / 75 / EU (Integrated 5 Pollution Prevention and Control) - Aries, E., Gómez Benavides, J., Mavromatis, S., Klein, G., Chronopoulos, G., Roudier, S - 2022 https: / / eippcb.jrc.ec.europa.eu / reference / ferrous-metals-processing-industry) . In fact the fumes that pass through the ceramic elements 110, 116 are charged of waste generated by combustion carried out by burners 107, 113: these 10 scores are deposited in the ceramic elements 110, 116 and over time they block them. Furthermore, the fumes contain acidic substances that cause corrosion of the ceramic elements 110, 116 and which damage the valves that regulate the supply of air or the release of fumes or other components. 15 Due to these aspects, the ability of the ceramic elements 110, 116 to ensuring adequate heat exchange deteriorates rapidly. It is noted hence the need to replace these ceramic elements frequently. It is clear that this leads to an increase in costs and makes it less efficient. the system given the need to intervene periodically to replace the 20 ceramic elements or other regenerative burner components The above problems are also found in other types of burners regenerative ones, such as rotary ones comprising a plurality of burners, those in radiant tube and in general also to the regenerative burners used in the ovens of the waste incinerators. 25 Summary of the invention ‐ 6 ‐ The purpose of the present invention is to provide a burner regenerative that is easy and economical to implement and that allows us to solve at least one of the drawbacks of the prior art solutions. Another object of the present invention is to provide a 5 regenerative burner which allows to reduce the frequency with which the ceramic elements must be replaced, which allows for lower costs maintenance of the regenerative burner and which allows to increase its efficiency. A first aspect of the present invention therefore concerns a 10 regenerative burner according to claim 1. The regenerative burner according to claim 1 is arranged for be used in a heating furnace at high temperatures temperatures, for example in a furnace of a steel plant (smelting furnace) forging, rolling, annealing, heating etc.) or in a furnace of a 15 incinerator. It is therefore clear that for "high-energy heating furnace “temperature” means any oven used to heat at high temperatures temperature a product regardless of the particular heat treatment that occurs in it. In practice the present invention is directed to a burner regenerative for a high-temperature heating furnace. A high-temperature heating furnace 20 high temperature heating (henceforth simply “oven”) presents a furnace and regenerative burner according to the present invention can be used to heat the relevant furnace and one or more possible products present in it. As is known, the oven can have a top, which can be mobile or stationary, on which the products to be heated are placed 25 (sheets, metal pipes, billets, waste etc.) and which can be heated for ‐ 7 ‐ by means of one or more regenerative burners according to the present invention. The regenerative burner can be realized in its general aspects according to the known art. In particular, the regenerative burner comprises at least a first burner and a second burner which are capable of generating 5 a flame to heat the products in the oven's furnace. In other words the regenerative burner may comprise two or more burners. The first burner and the second burner are configurable alternatively in a switched-on configuration, which corresponds to the first burner or second burner that generates a flame, or heat, and in a 10 off configuration, which corresponds to the first or second burner burner that does not generate a flame, or heat. In practice when the first burner is on the second burner is off and when the first burner is off the second burner is on. The regenerative burner preferably comprises a line of 15 air supply to the first burner which can also be set up for the exhaust of the fumes generated by the second burner and another supply line of air to the second burner which can also be set up for the exhaust of the fumes generated by the first burner. In the context of this invention, fumes are understood to mean a product of 20 combustion of the first burner or the second burner. The fumes produced by the first and second burners contain combustion waste, or simply “waste”, of different sizes. As known, the regenerative burner comprises a first element ceramic, or a first ceramic mass, and a second ceramic element, or a 25 second ceramic mass. ‐ 8 ‐ Preferably the first ceramic element is located in correspondence with the first burner while the second ceramic element is located in correspondence of the second burner. The first ceramic element and the second element ceramic can be housed in a collector duct positioned upstream of the 5 corresponding burner. As is known, their function is, in a first phase, to accumulate the heat, or energy, of the fumes and, in a second phase, to release such heat, or energy, to the supplied air. In practice when the first burner is lit, the fumes pass through the 10 second ceramic element that absorbs their heat, or energy, heating up. When the first burner goes out and the second burner comes on, the air passes through the second ceramic element and heats up. Therefore the second ceramic element releases heat to the air and the second burner uses less energy energy for its operation, i.e. it consumes less fuel (such as 15 example methane gas). The first ceramic element works in a mirror-like way to the first: it heats up when the second burner is on and subsequently gives off heat to the air supplied to the first burner. Advantageously, the regenerative burner includes at least one filter 20 refractory i.e. a filter made of refractory material. For the purposes of this invention, a refractory filter is understood to mean a filter made of a refractory material, i.e. capable of resisting high temperatures (for example up to 1650°C) without undergoing significant alterations. Such at least one refractory filter is positioned between the first burner and the 25 first ceramic element or between the second burner and the second element ‐ 9 ‐ ceramic. In practice at least one refractory filter can be found in correspondence of the first burner or in correspondence with the second burner. The at least one refractory filter is positioned in correspondence with the first burner or the second burner in the sense that it can be positioned upstream (or downstream) 5 depending on the direction considered) of one of them. For example, at least one filter refractory can be placed in a collector duct together with the first ceramic element or the second ceramic element. Regardless of how the regenerative burner is made, at least one refractory filter has the function of filtering the fumes coming from the second burner 10 and directed towards the first ceramic element or to filter the fumes coming from the first burner and directed towards the second ceramic element. Therefore, in light of the regenerative burner operation, at least one refractory filter is functionally arranged between the first ceramic element and the second burner or between the second ceramic element and the first burner. 15 In practice at least one refractory filter is configured to intercept the fumes generated by the second burner or the first burner in the on configuration and directed, respectively, to the first ceramic element or to the second element ceramic. The presence of at least one refractory filter allows the fumes to be filtered before 20 whether they are intercepted by the first ceramic element or by the second ceramic element; in practice the at least one refractory filter ensures that on the first ceramic element or on the second ceramic element a quantity is not deposited of flue gas waste such as to compromise the functionality of the regenerative burner and require frequent and expensive maintenance. 25 At least one refractory filter allows you to obtain these advantages - 10 - mainly in two ways. First of all, at least one refractory filter acts as a real filter in able to physically block the flue gas waste, or a part of it, preventing whether they reach the first ceramic element or the second ceramic element. 5 Furthermore, the at least one refractory filter causes the size to decrease of the waste that manages to pass through it. This may be due to the turbulent motions and collisions that occur during the crossing of the refractory filter. Therefore, even if part of the waste reaches the first ceramic element or second ceramic element, their size is 10 contained and does not cause the problems described above in reference to the burners regenerative according to the known technique, i.e. without at least one refractory filter. At least one refractory filter allows to block the flue gas waste in a regenerative burner district where the expulsion of waste is facilitated they are inside the furnace, where it is easier to intervene to eliminate them. 15 This helps to limit the number of interventions required for the cleaning and replacement of the various components of the regenerative burner. Furthermore, at least one refractory filter blocks, at least in part, the components acids present in the fumes so that the regenerative burner components result damaged to a lesser extent. 20 These advantages allow to reduce the maintenance costs of the regenerative burner and increase its efficiency because the first element ceramic or the second ceramic element remains less occluded by slag present in the fumes compared to what happens in regenerative burners without a refractory filter. 25 Preferably the at least one refractory filter comprises a plurality of - 11 - through holes. Preferably such through holes extend along a first direction corresponding, in use, to the direction that the fumes have when they pass through the at least one refractory filter towards the first ceramic element or the 5 second ceramic element. Preferably the through holes have a diameter between 15.0 mm and 60.0 mm. Preferably, said through holes have a circular cross-section. Preferably at least one refractory filter has an average of 30-70 2 2 2 holes / m, preferably 54-60 holes / m, even more preferably 57 holes / m 10 (obviously considered with respect to the two opposite faces in which they are obtained the through holes). At least one refractory filter is made of low / medium concrete cement content or any other material, or combination of materials, thermal shock resistant, high density and alloyed with high-performance elements 15 thermal conductivity The first ceramic element and the second ceramic element can be made of one or more of the following materials: mullite, alumina, cordierite or in any other material, or combination of materials, refractory with high resistance to thermal shock and alloyed with high conductivity elements 20 thermal. Preferably the first ceramic element and the second element ceramic include a multiplicity of through holes that extend along a second direction corresponding, in use, to the direction of the flow of fumes or air passing through the first ceramic element or the second element 25 ceramic. - 12 - Preferably the holes of the first ceramic element and / or the second ceramic elements have a circular, or honeycomb, or square or rectangular. Preferably the first ceramic element and / or the second element ceramic have an average of 1-10 holes / cm. 5 An additional advantage of having at least one refractory filter is that behave, in addition to the ceramic elements, as a component capable of absorb heat from the fumes of the first burner or the second burner and release them to the air supplied to the second burner or to the first burner. In the preferred embodiment the regenerative burner comprises 10 two refractory filters: a first refractory filter and a second refractory filter. The first refractory filter is positioned between the first ceramic element and the first burner, in such a way as to intercept the fumes generated by the second burner turned on and that are directed to the first ceramic element; the second refractory filter is positioned between the second ceramic element and the second burner, so as to 15 intercept the fumes generated by the first burner lit and which are directed to the second ceramic element. In this way it is possible to preserve the functionality of both ceramic elements and to maximize the benefits obtainable with this solution, even in terms of heat exchange. 20 According to a preferred embodiment, the regenerative burner It includes a pair of burners. In particular, the first burner and the second burner are arranged on opposite sides with respect to a plane of symmetry of the regenerative burner and are therefore spaced apart from each other. In practice the regenerative burner can present a plane of symmetry 25 which divides the regenerative burner into two parts and, precisely, the first burner - 13 - and the second burner are positioned in a mirror image to each other with respect to this plane of symmetry. When the regenerative burner is part of a heating furnace high temperatures equipped with a furnace and a mobile or stationary plate on the 5 where the products to be heated are placed, the first burner and the second burners are positioned on opposite sides of the furnace or moving floor. In particular, preferably the symmetry plane of the regenerative burner is orthogonal to the oven plane. The first burner and the second burner are facing each other. 10 In other words the first burner and the second burner are set up for generate a flame, or heat, one in the direction of the other, that is, in the direction of the symmetry plane. The regenerative burner includes a first air supply line prepared for the supply of air to the first burner in the on configuration 15 and a second air supply line set up for the supply of air to the second burner in on configuration. In practice the first line of air supply and the second line of air supply, when open, allows the air to be brought in, respectively, to the first burner and to the second burner. Obviously for the purposes of this 20 invention by air means combustion air necessary for the operation of the first burner and second burner. Preferably the first line of air supply is connected, or connected, to the first burner and the second line of air supply is connected, or connected, to the second burner. The first air supply line and the second air supply line 25 preferably have one or more respective valves arranged to open or - 14 - close the air passage in the respective first air supply line or second air supply line to the corresponding burner. The regenerative burner also includes a first exhaust line of the fumes and a second flue gas exhaust line. 5 The first flue gas exhaust line is positioned in correspondence with the first burner, that is, it is connected, or linked, to the first burner while the second flue gas exhaust line is positioned in correspondence with the second burner, that is, it is connected, or linked, to the second burner. The first flue gas exhaust line is designed to discharge the fumes 10 generated by the second burner when it is in the on configuration while the second flue gas exhaust line is designed to discharge the generated fumes from the first burner when it is in the on configuration. In practice, when the first burner is lit the air is brought to the first burner by means of the first air and flue gas supply line, passing 15 through the second switched off burner, are taken out of the system by the second flue gas exhaust line; when the second burner is on the air it is brought to the second burner by means of the second supply line of air and the fumes, passing through the first switched off burner, are discharged from the first flue gas exhaust line. 20 Alternatively the regenerative burner can be a burner rotary regenerative which comprises a plurality of burners and which is of the type shown in figure 2.21 on page 55 of the above mentioned document “Best Available Techniques (BAT) Reference Document for the Ferrous Metals Processing Industry” (year 2022). Or it could be a regenerative burner in a tube 25 radiant of the type shown on page 581 “Best Available Techniques (BAT) - 15 - Reference Document for the Ferrous Metals Processing Industry” (year 2022) comprising a first burner and a second burner and a single line associated with each of the first burner and the second burner. This line It works alternatively as an air supply line or a flue gas exhaust line. 5 In a second aspect, the present invention relates to a furnace high-temperature heating comprising one or more burners regenerative. The high-temperature heating furnace can be a furnace steelworks (such as a forging, rolling, annealing furnace, (heating) or an incinerator furnace. 10 Short list of figures Further features and advantages of the invention will become clearer. highlighted by examining the following detailed description of a form of preferred, but not exclusive, embodiment illustrated for illustrative purposes only and not limitative, with the support of the attached drawings, in which: 15 - Figure 1 is a schematic elevation view of a burner regenerative according to the known technique; - Figure 2 is a schematic elevation view of one form of preferred embodiment of a regenerative burner according to this invention; 20 - Figure 3 is a sectional view considered with respect to a plane orthogonal to the symmetry plane β shown in figure 2 and which concerns the filter refractory 19 and ceramic element 17; - figure 4 is a sectional view considered with respect to a parallel plane to the symmetry plane β shown in figure 2 and which concerns the refractory filter 19 and 25 the ceramic element 17; - 16 - - Figure 5 is a schematic top view of a steelworks furnace comprising a regenerative burner 1 shown in figure 2 and a burner regenerative 1' of the type shown in figure 1; this figure refers to a test experimental; 5 - figure 6 corresponding to the photographs of ceramic elements 11 and 17 of the regenerative burner 1 shown in figure 5, at the end of the test experimental; - figure 7 corresponding to the photographs of the ceramic elements 110 and 116 of the regenerative burner 1' shown in figure 5, at the end of the test 10 experimental; Detailed description of the invention Figure 2 schematically represents a form of preferred embodiment of a regenerative burner according to this invention; the regenerative burner is identified with the reference number 1. 15 The regenerative burner 1 may have the general characteristics of a regenerative burner according to the known technique, as described above with reference to figure 1. Regenerative burner 1 is associated with a furnace of a plant steelworks, for example it can be part of a forging furnace, a smelting furnace 20 rolling, of an annealing furnace or a reheating furnace. For this reason, figure 2 shows the moving floor of oven 2, on which are the heated products are moved in the oven, and the oven 3 where the heating of the products thanks to the regenerative burner 1. The plan where they are positioned products can be stationary. 25 The regenerative burner 1 has a plane of symmetry β, i.e. - 17 - includes a first part 4 (shown on the left) and a second part 5 (shown on the right) mirror each other with respect to the symmetry plane β. Knownly, each between the first part 4 and the second part 5 comprises: a line 6, 12 for the air supply, a corresponding valve 7, 5 13 to open or close the air passage in line 6 or 12, a burner 8, 14, a line 9, 15 for the exhaust of the fumes produced by the respective burner 8, 14 and a respective valve 10, 16 to close or open the passage of the fumes in the line 9, 15. The regenerative burner 1 also includes a ceramic element 10 housed in correspondence with each of the burners 8, 14. In particular, in corresponding to the burner 8 there is a ceramic element 11 and in A ceramic element 17 is housed in correspondence with the burner 14. The operation of the regenerative burner 1 can take place according to the known technique: burners 8 and 14 turn on and off alternately in 15 so as to heat the ceramic element 17 or 11 of the opposite part 5, 4 and preheat the air which will subsequently be supplied from line 12 or 6 of the part 5, 4. The ceramic elements 11, 17 can be made according to the technique note. For example, each ceramic element 11, 17 can be made in a 20 single piece or can be composed of one or more units arranged side by side to the other to constitute a ceramic element. The ceramic elements can be made of a material chosen from: mullite, alumina, cordierite or any other material, or combination thereof materials, refractory with high resistance to thermal shock and alloyed with elements 25 with high thermal conductivity. - 18 - Each of the ceramic elements 11, 17 has a multiplicity of holes passages made along the direction of transit of air or fumes through the regenerative burner 1. These holes can have a circular or honeycomb-shaped cross-section, or 5 square, or rectangular etc. Each hole can have an average size between 2.0 mm and 5.0 mm. Preferably the ceramic elements 11, 17 have an average of 1-10 holes / cm (obviously considered with respect to the two faces in which the holes open). 10 Advantageously, the regenerative burner includes at least one filter made of refractory material, hereinafter referred to as “filter refractory”, in correspondence with one of the two burners 8, 14 and arranged between the ceramic element 11, 17 and the respective burner 8, 14. For example, the regenerative burner 1 may include a filter 15 refractory 18 positioned in correspondence with the burner 8 and arranged between the ceramic element 11 and the burner 8, or a refractory filter 19 positioned in correspondence with the burner 14 and arranged between the ceramic element 17 and the burner 14. Preferably the regenerative burner 1 includes two refractory filters: 20 a first refractory filter 18 positioned in correspondence with the burner 8 and a second refractory filter 19 positioned in correspondence with the burner 14. The refractory filters 18 and 19 are made of refractory material, i.e. in a material capable of resisting high temperatures for long periods remaining chemically inert. 25 For example, refractory filters 18, 19 can be made of concrete - 19 - low / medium cement content or any other material, or combination of materials, resistant to thermal shock, high density and alloyed with elements with high thermal conductivity. The refractory filters 18, 19 have a multiplicity of through holes, 5 arranged to intercept the flow of air or fumes passing alternately in the corresponding burner 8, 14. Preferably these holes have a circular cross-section. Preferably these holes have a diameter between 15.0 mm and 60.0 mm. 10 Preferably these holes are made by arranging a series of pipes wrapped with an insulating material in the regenerative burner 1, or in a portion separable from the regenerative burner 1, and then providing for the creation of a jet in refractory material. Once the refractory material has solidified, it removes the pipes (this operation is made easier by the presence of the material 15 insulating) so as to obtain such refractory filter 18, 19. If the refractory filter 18, 19 had been obtained in a separable portion of the regenerative burner 1, yes obviously provides for associating this portion with the relative refractory filter 18, 19, to the rest of the regenerative burner 1. Preferably the refractory filters 18, 19 have an average of 30-70 holes / m, 2 2 20 preferably 54-60 holes / m, more preferably still 57 holes / m (considered obviously with respect to the two opposite faces in which the holes are made). Regardless of how the regenerative burner 1 is made (i.e. how the components and collectors are arranged among themselves) the refractory filters 18, 19 intercept the fumes directed towards the respective ceramic element 11, 17 and products 25 from burner 14, 8 opposite. - 20 - With reference to the arrows in figure 2 indicating the direction of the air and of the fumes and taking into account the normal functioning of a burner regenerative, it is clear that: when burner 8 is on and burner 14 is off, the air is supplied to burner 8 from line 6, passes through 5 the ceramic element 11 and the refractory filter 18, and is used as an oxidizer from burner 8 which generates the flame that heats furnace 3. The fumes produced by burner 8 are discharged through the second part 5, i.e. through the flue gas exhaust line 16 (as shown in figure 2 from the relevant arrows). 10 Therefore the fumes pass through the ceramic element 17: in the burners regenerate according to the known technique the waste and acid substances present in the fumes they accumulate in the ceramic element 17 and reach up to the line 15, causing the damages set out above in reference to the prior art. The presence of the refractory filter 19 allows to minimize such 15 drawbacks because waste and acidic substances are intercepted by the filter refractory 19 and arrive in lower quantities than the ceramic element 17 and the subsequent components of the regenerative burner 1. When burner 8 goes out and burner 14 comes on, the operation is the opposite: the refractory filter 18 intercepts and blocks, at least in 20 part, the waste and acid substances produced by the burner 14 preventing that they arrive in significant quantities at ceramic element 11 and line 9. In practice, the refractory filters 18, 19 determine the filtering and disintegration of the waste that passes through the filter holes due to the turbulence and the shocks generated during their passage through the holes of the refractory filters 18, 19. 25 At the same time, the refractory filters 18, 19 act as a physical filter for the ‐ 21 ‐ acidic substances present in the fumes which remain blocked, at least in part, in the refractory filters 18, 19 without going any further. For example, in figures 3 and 4 schematic views are shown of sections of the regenerative burner 1 at the refractory filter 19 and 5 of the corresponding ceramic element 17. Figure 3 is a section considered with respect to a plane orthogonal to the plane of symmetry β while figure 4 is a section considered with respect to a plane parallel to the symmetry plane β. The direction of the passage of the fumes is indicated by the arrows in figure 4. 10 Figures 3 and 4 also schematically show the filter holes 22 refractory 19. The Applicant has carried out a qualitative experimental test for evaluate the filtering capacity of refractory filters 18, 19. This experimental test will be described with reference to figures 5-7. 15 Figure 5 schematically represents the 120 oven used from above: it is It is a rolling furnace, comprising a 2' mobile plate for the movement of the billets in the direction indicated by the arrow in figure 5. Of course it is possible to use the regenerative burner 1 in any other high-temperature heating furnace, such as iron and steel furnaces or blast furnaces 20 incinerators. The 120 oven includes various regenerative burners arranged in series on the sides of the 2nd moving plane. Among the various regenerative burners, regenerative burner 1 stands out, highlighted with a circle, and a 1' regenerative burner, highlighted with a 25 square. The regenerative burner 1 is of the type described in figures 2-4: ‐ 22 ‐ comprises two burners 8, 14, two corresponding ceramic elements 11, 17 and refractory filters 18, 19 (not visible in figure 5). The regenerative burner 1' is of the type described in figure 1, i.e. it comprises two burners 107, 113, two corresponding ceramic elements 110, 116 (not shown in figure 5) and is without filters 5 refractory. The 120 oven was operated by alternately turning on the burners of each regenerative burner, as described above. Furthermore, the 120 oven was kept in operation for 12 months and at the end the state of the ceramic elements was visually compared. 10 Figures 6 and 7 are photographs, respectively, of the elements ceramics 11, 17 of the regenerative burner 1 and of the ceramic elements 110, 116 of the regenerative burner 1'. It is evident that the ceramic elements of burner 1' have a level higher than the slag deposited on their surface; in fact the ceramic elements of the 15 regenerative burner 1 are practically slag-free. In practice, from the comparison between figures 6 and 7 it is clear that the refractory filters 18, 19 preserve the ceramic elements 11, 17 from the accumulation of slag present in the fumes generated by the burners, ensuring longer-lasting effectiveness, a longer duration and allowing to contain the costs for the 20 maintenance / replacements for regenerative burners. Refractory filters 18, 19 are less expensive than ceramic elements; therefore, Replacing the refractory filters 18, 19 has a lower cost than having to replace the ceramic elements. Furthermore, the presence of refractory filters 18, 19, allows the accumulation of waste in regenerative burner districts where it is more 25 easy for them to be expelled into the furnace when the relevant line for ‐ 23 ‐ the air supply is opened. This further allows for a reduction in costs and interventions. system maintenance and replacements. The test showed that the slag present on the ceramic elements 11, 17 5 are smaller in size than those that normally accumulate on the ceramic elements of regenerative burners without refractory filters; evidently the refractory filters, in addition to acting as a filter for larger sized waste, determine a reduction in the waste that manages to pass through the filter, causing a decrease in their harmfulness to ceramic elements. 10 The use of refractory filters 18, 19 did not cause any pressure drops or during the flue gas calibration phase or during the air supply calibration phase. Finally, it was noted that the presence of refractory filters 18, 19 allows for obtain an increase in the capacity of the regenerative burner 1 to save energy by extracting heat from the fumes and releasing heat into the supplied air. 15 In a test conducted in situations similar to the previous one, they were place two thermocouples TC1, TC2 upstream and downstream of the refractory filter 19, in the position shown in figure 4. Two similar thermocouples were placed in the same positions in a regenerative burner without refractory filters. 20 The tables below show, for each regenerative burner, the data relating to the operation of the regenerative burner for 5 consecutive hours; in In particular, the minimum difference for each hour of operation is indicated and the maximum difference between the temperature T2 detected with the thermocouple TC2 and the temperature T1 detected with the thermocouple TC1, and the average of the differences. 25 Table 1 corresponds to the data collected for the regenerative burner 1' without ‐ 24 ‐ of refractory filters: Without filter T2-T1 [°C] refractory min max average I now 0.5 20.9 9.3 2nd hour 5.9 24.8 13.7 3rd hour 5.6 21.7 12.6 4th hour 5.6 20.8 12.6 V hour 2.5 23.0 9.5 Table 1 Table 2 corresponds to the data collected for regenerative burner 1 equipped with refractory filters 5 With filter T2-T1 [°C] refractory min max average I now 18.1 57.4 45.3 II hour 15.7 68.0 60.7 3rd hour 8.4 54.1 48.6 4th hour 10.0 67.0 58.2 V hour 18.0 64.3 55.1 Table 2 It is evident that the presence of refractory filters determines a difference between the T2 temperature and the more marked T1 temperature. This is proof that the heat exchange is more accentuated if a regenerative burner is used 1 10 equipped with refractory filters. These data demonstrate that using a regenerative burner 1 is - 25 - it is possible to obtain a greater efficiency in heat exchange and therefore, also a further reduction in the costs required to operate the plant. It is likely that this advantage is achieved, first of all, by the fact 5 same that refractory filters are provided which allow to increase the useful surface for heat exchange and, secondly, due to the fact that the filters refractory materials allow to limit the quantity of slag that settles on the elements ceramics and the size of the slag itself; therefore the refractory filters, in addition to increase the useful life of the ceramic elements, allowing to maintain high 10 time the efficiency of ceramic elements in heat exchange. To the present invention, in the embodiments illustrated and described, in order to satisfy contingent and specific needs, a technician in the field will be able to make numerous changes and modifications, all of which are included within the scope of protection of the invention as defined by the following 15 claims. ‐ 26 ‐

Claims

1. A regenerative burner (1) comprising: at least a first burner (8) and a second burner (14) alternatively configurable in an on-state configuration and in an off-state configuration, and at least a first ceramic element (11) and a second ceramic element (17), said first ceramic element (11) and said second ceramic element (17) being able to accumulate the heat of the fumes generated, respectively, by the second burner (14) and by the first burner (8) in the on-state configuration, and to transfer said accumulated heat to the air supplied, respectively, to the first burner (8) and to the second burner (14) in the on-state configuration, characterised by the fact that it comprises at least one refractory filter (18, 19) positioned: between said first burner (8) and said first ceramic element (11), or between said second burner (14) and said second ceramic element (17), and by the fact that said at least one refractory filter (18, 19) is positioned: between said first burner (8) and said first ceramic element (11), or between said second burner (14) and said second ceramic element (17), and by the fact that said at least one refractory filter (18, 19) is positioned:19) is configured to intercept the fumes generated by the second burner (14) in the on configuration and directed to the first ceramic element (11) or to intercept the fumes generated by the first burner (8) in the on configuration and directed to the second ceramic element (17)., 2. Regenerative burner (1) according to claim 1, wherein said at least one refractory filter (18, 19) comprises a plurality of through holes -27GFEL005BIT GF-ELTI Srl Biesse Srl (22) obtained in opposite surfaces of said at least one refractory filter (18, 19).

3. Regenerative burner (1) according to claim 2, wherein said through holes (22) extend along a first direction corresponding, in use, to the direction of the flow of fumes directed towards said first ceramic element (11) or towards said second ceramic element (17).

4. Regenerative burner (1) according to claim 2 or claim 3, wherein said through holes (22) have a diameter between 15.0 mm and 60.0 mm.

5. Regenerative burner (1) according to any of claims 2-4, wherein the through holes (22) have a density of 30-70 foh / m2, preferably 54-60 holes / m2, more preferably still 57 holes / m2 6. Regenerative burner (1) according to any of the preceding claims, wherein said at least one refractory filter (18, 19) is made of low / medium cement concrete or any other material, or combination of materials, resistant to thermal shock, of high density and alloyed with elements with high thermal conductivity.

7. Regenerative burner (1) according to any of the preceding claims, wherein said first ceramic element (11) and said second ceramic element (17) are made of one or more of the following materials: mullite, alumina, cordierite or any other material, or combination of materials, refractory with high resistance to thermal shock and alloyed with elements with high thermal conductivity.

8. Regenerative burner (1) according to any of the preceding claims, wherein each of said first ceramic element (11) and second ceramic element (17) comprises a plurality of through holes having -28GFEL005BIT GF-ELTI Srl Biesse Srl a cross-section with a circular or honeycomb shape, or square or rectangular.

9. Regenerative burner (1) according to any of the preceding claims, wherein said at least one refractory filter (18, 19) is adapted to accumulate the heat of the fumes generated by said second burner (14) or by said first burner (8) in the on-state configuration and to release the accumulated heat to the air supplied, respectively, to said first burner (8) or to said second burner (14) in the on-state configuration.

10. A regenerative burner (1) according to any of the preceding claims, comprising a first refractory filter (18) and a second refractory filter (19), and wherein: said first refractory filter (18) is positioned between said first burner (8) and said first ceramic element (11), said first refractory filter (18) being configured to intercept the fumes generated by said second burner (14) in the on-state configuration, and said second refractory filter (19) is positioned between said second burner (14) and said second ceramic element (17), said second refractory filter (19) being configured to intercept the fumes generated by said first burner (8) in the on-state configuration.

11. Regenerative burner (1) according to any of the preceding claims, comprising: a first line (6) for supplying air to said first burner (8) and a second line (12) for supplying air to said second burner (14); a first line (9) for exhausting the fumes generated by said second burner (14), said first fume exhaust line being connected to said first burner (8), and a second line (15) for exhausting the fumes generated by said first burner (8), said second fume exhaust line (15) being connected to said second burner (14), wherein each of said lines (6, 9, 12, 15) is provided with one or more valves (7, 10, 13, 16) configured to open or close the respective line (6, 9, 12, 15),and wherein: said first burner (8) in the on configuration corresponds to said first air supply line (6) open and to said second smoke exhaust line (15) open, said second burner (14) being in the off configuration, said first smoke exhaust line (9) closed and said second air supply line (12) closed, and said second burner (14) in the on configuration corresponds to said second air supply line (12) open and to said first smoke exhaust line (9) open, said first burner (8) being in the off configuration, said second smoke exhaust line (15) closed and said first air supply line (6) closed., 12. A regenerative burner according to any of the preceding claims 1-10, comprising: a first single line connected to said first burner and configured to alternatively supply air to said first burner in the on-state configuration and exhaust fumes generated by said second burner in the on-state configuration, a second single line connected to said second burner and configured to alternatively supply air to said second burner in the on-state configuration and exhaust fumes generated by said first burner in the on-state configuration, -30GFEL005BIT GF-ELTI Srl Biesse Srl said regenerative burner being a rotary regenerative burner comprising a plurality of burners or a radiant tube regenerative burner.

13. A high temperature heating furnace comprising a furnace (3) and one or more regenerative burners (1) according to one or more of the preceding claims 1-12 arranged to heat the products in the furnace (3).

14. Furnace according to claim 14, said furnace being a steel furnace or a furnace of a waste incinerator.