Device for heating steel products

Abstract

A device (10) for heating a steel product (200), in particular a blank, comprises a heating chamber (13), a plane of travel (P) defined inside the heating chamber (13), and feeding and extraction means (18, 20) for the steel product.

Description

Technical Field

[0001] The embodiments described herein relate to an apparatus for heating steel products (e.g., metal or non-metal products, such as those made of alloys).

[0002] This utility model specifically relates to semi-finished steel products, such as billets or steel ingots, that are subsequently sent for rolling. Background Technology

[0003] A furnace is known for heating steel products (such as billets or slabs) to raise the temperature of semi-finished metal to a value suitable for rolling.

[0004] Traditional heating furnaces are equipped with water-based cooling systems for structural components subjected to high heating stress. They typically have heating chambers in which steel products move continuously or intermittently between the inlet and outlet. Corresponding to the inlet and outlet are corresponding roller conveyors for inserting and extracting products, as well as possible loaders and unloaders.

[0005] The heating chamber has a travel plane, which can be constructed in different ways depending on the circumstances. In a furnace with movable longitudinal members (more commonly referred to as a walking beam heating furnace), the travel plane is alternately defined by fixed beams and movable beams arranged parallel to the length of the travel plane.

[0006] There are also furnaces without water-based cooling systems, where the processed material forms pipes, so the product is much lighter than a billet or slab, and heating and heat treatment are performed at much lower temperatures.

[0007] In these furnaces used for pipes, if the heating requirements are low, the burners are placed only above the so-called “rolling line” because the pipes are light and have a hollow circular cross-section, and are designed to rotate as they move forward, in such a way that heating (at not particularly high temperatures) occurs uniformly over their entire surface.

[0008] Conversely, given that billets or steel billets are heavier products with square / rectangular / polygonal / circular cross sections, it is impossible to rotate them during movement, so the heating and heat treatment temperatures must be much higher.

[0009] Examples of such furnaces, primarily used for pipelines, are described in documents GB1473645, DE3339585, and WO2012 / 052960.

[0010] Specifically, document GB1473645 describes a furnace for tempering steel pipes, having movable longitudinal members shaped to accommodate the pipes, which, as described above, rotate as they advance. Burners are present only on one upper wall of the furnace.

[0011] Document DE3339585 also relates to furnaces for heating pipes, special profiles, etc., wherein burners are installed on the upper wall of the furnace in a heating chamber in which only pipes exist, while other burners are installed in a separate lateral chamber that is different from the heating chamber.

[0012] Document WO2012 / 052960 describes a conveyor with a movable longitudinal member, and a furnace including said conveyor for heat treatment of metallurgical products. This document does not consider or solve the problem of heating these products, but only addresses the problem of moving them.

[0013] In the processing of the pipe, the heating process occurs in a controlled manner because the heating serves to achieve a change in the crystal structure, which determines the mechanical properties of the pipe itself.

[0014] Conversely, in the heating of billets and steel billets, the purpose is not to change the crystal structure, but simply to heat the metal products so that they reach a temperature suitable for subsequent processing.

[0015] In a known furnace, metal products are arranged to rest on beams, extending laterally to their longitudinal direction.

[0016] Fixed beams are associated with fixed support frames, while movable beams are associated with one or more movable support frames to ensure proper product feeding.

[0017] The supporting frame (especially the beams and the elements that support them) and the sections of the roller conveyor (because they are located inside the heating chamber) are subjected to severe thermal and mechanical stresses due to the heating parameters required for the handling of billets and steel billets.

[0018] Typically, considering the high temperatures reached inside the furnace (which can vary between approximately 600 and 1250°C) and the relatively large weight of the metal products being processed, conventional heating furnaces used for steel billets and slabs require ensuring that the components inside the furnace maintain appropriate mechanical properties and that the water-based cooling system does not deform or deteriorate.

[0019] Given the high mechanical loads that the support components must withstand, and considering the weight of the billet and billet, which is much greater than that of the pipe, such deformation and deterioration are particularly dangerous and harmful.

[0020] On the other hand, the cooling of these components increases the removal of heat from the chamber, requiring the burner to have a larger thermal input to reach the desired temperature. This increased thermal input directly correlates with higher fuel consumption, higher operating costs, and higher emissions of gases such as CO2 and NO. X And other higher emissions into the atmosphere.

[0021] Document EP2678458 describes an alloy particularly suitable for use in furnace constructions, especially in furnaces where there is no actual movement of the product and the heating process occurs in a discontinuous manner. In such furnaces, there are no structural mechanical stresses caused by the combination of product weight and movement, as well as high temperatures. Therefore, this material is unsuitable for use in walking beam furnaces for heating steel products (such as billets or slabs) that move within the furnace.

[0022] Another problem associated with water-based cooling of these components is that water causes black lines on the lower outer surface of the billet and slab, corresponding to the cooled beams, known as "slip marks." To reduce this phenomenon, conventional walking beam furnaces use a device called a "rider," which reduces the problem but does not eliminate it, and this becomes particularly critical for subsequent rolling operations.

[0023] One of the advantages of traditional walking beam furnaces is their limited length, due to the fact that much higher temperatures can be reached inside, resulting in a shorter residence time for the billet. However, the high temperatures lead to the formation of a large amount of oxide scale on the surface of the billet itself. The oxide scale formed results in scrap when removed, leading to material loss, which in turn leads to a reduction in the weight of the semi-finished product and consequently, poor performance in terms of the yield of the operation used for converting or processing steel.

[0024] Therefore, there is a need to improve a device for heating steel products that can overcome at least one of the shortcomings of the prior art. Utility Model Content

[0025] In particular, one object of this invention is to provide a heating device that does not suffer from the disadvantages of using a liquid-based cooling system.

[0026] Another objective of this invention is to provide a heating device with reduced environmental impact, particularly related to the emission of gases into the atmosphere.

[0027] Another objective of this invention is to provide a heating device with lower management and maintenance costs than conventional devices.

[0028] Another object of this invention is to provide a device having a particularly compact vertical extension to simplify construction work during initial installation.

[0029] Another objective of this invention is to obtain a heating product with a uniform thermal gradient and no cold spots or cold zones.

[0030] The applicant has designed, tested and implemented this utility model to overcome the shortcomings of the prior art and to obtain these and other objectives and advantages.

[0031] The independent claims set forth and demonstrate the features of this invention. The dependent claims describe other features of this invention or variations of the main inventive concept.

[0032] In accordance with the above objectives, this utility model relates to a device for heating steel products (such as steel billets or billets), which overcomes the limitations and eliminates the defects of the prior art, comprising:

[0033] - A heating chamber extending between an inlet and an outlet, wherein at least one inlet region, an intermediate region, and an outlet region are sequentially defined within the chamber.

[0034] - A travel plane, which is alternately defined inside the heating chamber by fixed support elements and movable support elements, the fixed support elements and the movable support elements being arranged parallel to the length of the device and supported by a plurality of fixed support elements and movable support elements respectively.

[0035] - A device for feeding and extracting metal products, which is provided with corresponding feed rollers and extraction rollers respectively associated with the inlet end and the outlet end.

[0036] - Heating and / or combustion components, such as burners, are arranged above and below the plane of travel.

[0037] According to the first aspect, the fixed and movable support elements, the fixed and movable bearing elements, and the feed and extraction rollers are made of a metal superalloy comprising a combined percentage of at least about 30% to about 60% nickel and cobalt and about 24% to about 35% chromium.

[0038] Because of the specific metal superalloys used to manufacture fixed and movable support elements, as well as feed and extraction rollers, liquid-based cooling is not necessary, which is always required in conventional furnaces used to heat billets or slabs.

[0039] Therefore, the device according to this invention does not have a liquid-based, especially water-based, cooling system inside the heating chamber.

[0040] In another preferred embodiment, the metal superalloy comprises between about 40% and about 50% nickel, between about 25% and about 35% chromium and cobalt, combined with up to 10% of one or more other elements, wherein the superalloy also contains a combination of other components between 5% and 50%.

[0041] On the other hand, the fixed and movable support elements, the fixed and movable bearing elements, and the feed and extraction rollers are each made of different metal superalloys, depending on the region of the heating chamber they are located in and the different operating temperatures present there. In this case, the different metal superalloys used have at least an increasing nickel and chromium content from the inlet region to the outlet region.

[0042] According to another aspect, at least the fixed and movable support elements, the fixed and movable bearing elements, and the feed rollers present in the inlet area are made of a first metal superalloy.

[0043] The fixed and movable support elements and the fixed and movable bearing elements existing in the intermediate region are made of a second metal superalloy, which is different from the first metal superalloy.

[0044] The fixed and movable support elements, fixed and movable bearing elements, and extraction rollers present in the export area are made of a third metal superalloy, which is different from the first and second metal superalloys.

[0045] All three metal superalloys (the first, the second, and the third) are characterized by including certain amounts of nickel and chromium, comprising at least 50% and up to 90% of their composition.

[0046] The total nickel and chromium content of the first metal superalloy is lower than that of the second metal superalloy.

[0047] The total nickel and chromium content of the second metal superalloy is lower than that of the third metal superalloy.

[0048] As described above, this solution allows for the complete elimination of traditional water-based cooling because the metal superalloy used allows the structural components inside the heating chamber to withstand temperatures without the need for a liquid-based cooling system, while ensuring the required structural resistance.

[0049] In this way, the overall efficiency of the device is improved, and the corresponding emissions into the atmosphere are reduced. The quality and uniformity of the heated product are also better because the contact with the support element does not cause marks or residues due to temperature differences between the reciprocating surfaces.

[0050] Differentiating materials according to different zones of the heating chamber allows for optimization of component performance under load, thereby finding a trade-off between investment costs and required heat resistance. In fact, different zones have corresponding operating temperatures, which, combined with the weight of the metal product, necessitate defined thermo-mechanical sealing characteristics for all supporting and moving elements.

[0051] In another embodiment, the movable support element is manufactured through the bottom wall of the heating chamber and fixed to a single support frame, which is arranged below the bottom wall and associated with the moving device. Advantageously, the presence of the single support frame restricts the space required for its movement, thereby allowing for a more compact device.

[0052] According to another aspect, the device includes a lateral inlet and a lateral outlet, both of which are associated with a corresponding closing unit. The closing unit is provided with a door and a corresponding moving mechanism, preferably a pantograph-type moving mechanism.

[0053] According to another aspect, the aforementioned closed unit includes multiple inert gas delivery devices associated with the inlet and outlet ports to create a gas barrier that prevents the atmosphere of the heating chamber from being contaminated by external air, thereby limiting the entry of oxygen from the outside and thus limiting the generation of flakes, and also preventing harmful gases (such as CO and NOx) from escaping from the furnace.

[0054] In another embodiment, the feed and extract rollers are arranged inside the heating chamber, passing through and suspended from the respective front and rear end walls of the heating chamber. The feed and extract device includes a plurality of additional inert gas delivery devices configured to create a vented seal for the feed and extract rollers. By restricting oxygen entry into the furnace, these precautions allow for a reduction in flake formation and the escape of harmful gases from the furnace.

[0055] According to one aspect, the device includes loading and unloading devices corresponding to the inlet and outlet respectively inside the chamber to position the steel product from the feed roller on the travel plane and from the travel plane on the extraction roller. Attached Figure Description

[0056] Referring to the accompanying drawings, these and other aspects, features, and advantages of the present invention will become clear from the following description of some embodiments given as non-limiting examples, in which:

[0057] Figure 1 This is a schematic side view of an apparatus for heating steel products according to some embodiments described herein;

[0058] - Figure 2 It is along Figure 1 The cross section of line II-II;

[0059] - Figure 3 It is along Figure 1 The cross section of line III-III;

[0060] - Figure 4 This is the front view of a closed unit;

[0061] - Figure 5 yes Figure 4 Side view;

[0062] - Figure 6 This is a schematic diagram of the feeding or extraction device;

[0063] - Figures 7-9 It includes Figures 1-6 A schematic side view of a heating device used in the production of steel products;

[0064] - Figure 10 These are variations of the apparatus for heating steel products according to some embodiments described herein;

[0065] - Figure 11 It is along Figure 10 A cross-sectional view of line XI-XI.

[0066] For ease of understanding, the same reference numerals are used to identify the same common elements in the figures where possible. It should be understood that elements and features of one embodiment can be readily combined or incorporated into other embodiments without further explanation. Detailed Implementation

[0067] Reference will now be made in detail to feasible embodiments of the present invention, examples of one or more of which are illustrated in the accompanying drawings by way of non-limiting illustration. The wording and terminology used herein are also for the purpose of providing non-limiting examples.

[0068] Figure 1 An apparatus 10 for heating a steel product 200 is shown. The steel product may be a cast semi-finished product, typically a steel billet or billet.

[0069] The steel product 200 under discussion has a solid cross-section and is square, rectangular, polygonal, or circular in shape. Furthermore, each steel product 200 may have a weight between about 0.5 tons and about 5 tons, preferably between about 0.5 tons and about 2.5 tons.

[0070] In the following text, for the sake of simplicity, we will only refer to billet 200 by way of example.

[0071] Device 10 is a furnace with fixed and movable rods (or longitudinal members), also known as a walking beam furnace.

[0072] exist Figure 1 In this furnace 10, a heating chamber 13 extends between an inlet 11 and an outlet 12. Within the heating chamber 13, an inlet or recovery zone A, an intermediate or preheating zone B, and an outlet or heating and balancing zone C are defined in sequence, each characterized by a different operating temperature.

[0073] The inlet region A is characterized by a maximum temperature of approximately 1000°C, the intermediate region B is characterized by a maximum temperature of approximately 1100°C, and the outlet region C is characterized by a maximum temperature of approximately 1150°C.

[0074] See details Figures 2-3 Inside the heating chamber 13, there is a travel plane P that is alternately defined by fixed support elements 14 and movable support elements 15, all of which are arranged to extend parallel to the length of the furnace 10.

[0075] Support elements 14 and 15 support the blanks 200 while allowing them to advance gradually between the inlet 11 and the outlet 12.

[0076] The fixed support element 14 and the movable support element 15 are supported by the fixed support element 16 and the movable support element 17, respectively.

[0077] By way of example only, the fixed support element 14 and the movable support element 15 can be made of beams or longitudinal members, configured as "I", while the fixed support element 16 and the movable support element 17 can be made of pipes with circular cross sections.

[0078] The fixed support element 14 and the movable support element 15 have corresponding resting surfaces for the blank 200, which are substantially flat and do not have any shaped parts whose shape matches the cross-section of the blank 200.

[0079] However, in the case of steel products with, for example, a circular cross-section, it is not ruled out that the surface can have a recessed solution.

[0080] The furnace 10 includes a feeding device 18 and an extraction device 20. The feeding device is associated with an inlet 11 and equipped with a feeding roller 19, and the extraction device is associated with an outlet 12 and equipped with an extraction roller 21, so as to move each billet 200 inside and outside the heating chamber 13, respectively.

[0081] According to one aspect, the fixed and movable support elements 14, 15, the fixed and movable support elements 16, 17, and the feed and extraction rollers 19, 21 are made of a metal superalloy comprising a combination of at least about 30% to about 60% nickel and cobalt and about 24% to about 35% chromium.

[0082] Superalloys also contain between about 5% and about 50% of other chemical components or combinations of elements.

[0083] The combination of other chemical components can advantageously vary depending on the arrangement of the fixed and movable support elements 14, 15, fixed and movable support elements 16, 17, and the feed and extraction rollers 19, 21 within the furnace 10. In another preferred embodiment, the metal superalloy comprises between about 40% and about 50% nickel, between about 25% and about 35% chromium, and cobalt, combined with a maximum of 10% of one or more other elements. In this case, the superalloy comprises a combination of other components between 5% and 35%.

[0084] In another improvement of this invention, the fixed and movable support elements 14, 15, the fixed and movable support elements 16, 17, and the feed and extraction rollers 19, 21 are made of different metal superalloys depending on their location in the device 10. In this case, the metal superalloy has an increasing content of at least nickel and chromium from the inlet region A to the outlet region C.

[0085] According to one embodiment, the fixed and movable support elements 14, 15, fixed and movable support elements 16, 17, and feed roller 19 present in the inlet region A are made of a first metal superalloy M1.

[0086] The fixed and movable support elements 14, 15, 16, and 17 existing in the intermediate region B are made of the second metal superalloy M2.

[0087] The fixed and movable support elements 14, 15, fixed and movable support elements 16, 17, and extraction roller 21 present in the exit area C are made of a third metal superalloy M3.

[0088] Metallic superalloys M1, M2, and M3 include nickel and chromium as major components, comprising at least 70% and up to 90% of their composition. In this case, the superalloy includes a combination of other components between 10% and 30%.

[0089] Other chemical components that complete the chemical composition of the superalloy may include aluminum, iron, tantalum, zirconium, vanadium, magnesium, calcium, carbon, boron, phosphorus, molybdenum, and tungsten. Other components may include, but are not limited to, titanium, silicon, niobium, manganese, and cobalt.

[0090] The total nickel and chromium content of the first metal superalloy M1 is lower than that of the second metal superalloy M2, and the total nickel and chromium content of the second metal superalloy M2 is lower than that of the third metal superalloy M3.

[0091] Manufacturing components within the heating chamber using metal superalloys M1, M2, and M3 allows for a significant simplification of the furnace 10 layout, as a liquid-based cooling system for these components is not necessary. Furthermore, the absence of cooling prevents the maintenance of a more uniform temperature within the chamber, directly impacting the quality of the heated product, fuel consumption, and gas emissions into the atmosphere.

[0092] Furthermore, the lack of liquid-based cooling eliminates the problem of slip marks because, in each case, the area where the billet 200 rests is at the same temperature as the latter.

[0093] Metallic superalloys M1, M2, and M3 are particularly resistant to loads applied at high temperatures. This is especially important in the field of heating billets 200, which are particularly heavy and require high heating temperatures and / or long residence times inside the heating chamber 13 due to their structure.

[0094] According to some embodiments, the first metallic superalloy M1 comprises 30-40% Ni+Co, 24-30% Cr, 1-5% W+Nb+Ti, and 1-4% C+Si+Mn. In this case, the superalloy includes a combination of other components between 21% and 44%.

[0095] The second metallic superalloy M2 comprises 40-50% Ni, 25-35% Cr, up to 10% W+Co, up to 1% C, up to 3% Si+Al, and up to 3% Mn. In this case, the superalloy includes a combination of other components up to 35%.

[0096] The third metallic superalloy M3 comprises 45-60% Ni+Co, 25-35% Cr, 8-16% W, and 1-4% C+Si+Al. In this case, the superalloy includes a combination of other components up to 21%.

[0097] This difference in superalloy composition allows the thermo-mechanical properties of the material to be adapted according to the temperatures present in different regions of the heating chamber 13, while also taking into account economic factors. In fact, considering the increased cost of superalloys due to their increased thermal resistance characteristics, and the tooling and maintenance costs, the solution of this invention optimizes the trade-off between the thermal resistance and efficiency of the material used. This defined material also supports heavy blanks 200, which becomes even more important if applied to support components at high temperatures.

[0098] According to some embodiments, the feed path for the billet 200 is defined inside the chamber 13, which extends linearly on the travel plane P between the inlet 11 and the outlet 12, with the billet 200 corresponding to the path entering and exiting the furnace 10 respectively.

[0099] The heating chamber 13 is defined by an upper wall 22 and an opposite bottom wall 23, a first end wall 24 and a second end wall 25, and two side walls 26 and 27 that are substantially parallel to each other.

[0100] Figure 1 In the middle, the wall as described above can be covered with a refractory plate 28 in order to limit heat loss to the outside.

[0101] The travel plane P is horizontal and located at an intermediate height between the upper wall 22 and the bottom wall 23. The travel plane P is substantially parallel to the bottom wall 23 and has a slightly smaller extension than the bottom wall.

[0102] According to some embodiments, regions A, B, and C may be defined by the geometry between the upper wall 22 and the bottom wall 23. In particular, the upper wall 22 may have segments with a larger or smaller distance from the bottom wall 23, thereby defining regions with larger or smaller cross-sections for air passage.

[0103] The fixed support elements 16 are orthogonally fixed to the bottom wall 23 and aligned longitudinally in groups to support the corresponding fixed support elements 14.

[0104] Movable support elements 17 extend through the bottom wall 23, are grouped and longitudinally aligned to support corresponding movable support elements 15, and are fixed to a single support frame 29 disposed below the bottom wall 23 and associated with the moving device 30. The presence of the single support frame 29 allows for limiting the volume of the technical chamber below the furnace 10, thus simplifying and limiting the cost of the construction work required to build / install the furnace 10.

[0105] However, it cannot be ruled out that the support frame 29 can be divided into two or more independent structures.

[0106] For each movable support element 17, the bottom wall 23 has a hole 38 having a longitudinal extension coherent with the applied forward-retracting step. Each hole 38 can be sealed by means of a through-sealing element 39 that cooperates with the inner surface and the opposite outer surface of the bottom wall 23.

[0107] The moving device 30 is configured to allow combined forward-lifting and lowering-retracting movements of the support frame 29.

[0108] See especially Figures 1-3 The moving device 30 includes two groups or rows, each group or row including four aligned moving units 31, the moving units 31 being arranged to rest on the mounting plane of the furnace 10 and below the support frame 29, on which the support frame rests.

[0109] Each movable unit 31 may include a connecting rod 32, which can be selectively driven to move the support frame 29.

[0110] The moving unit 31 can be driven independently, or, as described herein, one moving unit 31 in each group can be driven and synchronously guide the movement of all other moving units.

[0111] Therefore, some moving units 31 are associated with corresponding electromechanical devices to move the connecting rod 32, which is driven by a hydraulic cylinder or an electric cylinder.

[0112] The furnace 10 includes an inlet hole 33 and an outlet hole 34. The inlet hole 33 is arranged to correspond to the inlet end 11, more preferably to the side wall 26 or 27, and the outlet hole 34 is arranged to correspond to the outlet end 12, more preferably to the side wall 26 or 27.

[0113] The corresponding closing unit 35 is associated with the inlet hole 33 and the outlet hole 34.

[0114] Each closing unit 35 includes a door 36 and a pantograph mechanism 37 for moving the door 36.

[0115] The closure unit 35 may include multiple devices 42 for supplying inert gases (e.g., nitrogen). The devices 42 are arranged around the periphery of the openings 34, 35 and configured to create a gas barrier that prevents hot air from escaping with gases (e.g., CO) towards the outside of the furnace 10 and prevents air from entering from the outside. In this way, the risk of operator infection and environmental contamination is limited, and the formation of oxide scale is also reduced.

[0116] According to some embodiments, the feed roller 19 and the extraction roller 21 are located inside the heating chamber 13 and are arranged to pass through and be suspended from the front end wall 24 and the rear end wall 25, respectively, wherein the respective axes of rotation are parallel to the direction of advance of the billet 200 inside the furnace 10.

[0117] Rollers 19 and 20 define the corresponding roller conveyors arranged across the holes 33 and 34 of the furnace 10.

[0118] Rollers 19 and 20 are supported by a rotating shaft 41, which is driven individually or in groups by one or more drive devices 40.

[0119] The portion of each rotating shaft 41 outside the heating chamber 13 is protected by a metal box 42, which extends to flanges for connection with the walls 24, 25 of the furnace 10.

[0120] The feeding device 18 and the extraction device 20 include a plurality of additional devices 44 for delivering an inert gas (e.g., nitrogen), which are configured to deliver the gas inside the metal box 42 to create a barrier that prevents hot air from escaping toward the outside of the furnace 10 and prevents air from entering from the outside, which would contaminate the atmosphere of the heating chamber 13 and increase the amount of oxide scale formed on the surface of the billet.

[0121] The specific combination of materials was selected to manufacture the internal components of the furnace and the aforementioned nitrogen seals, which allows for a significant reduction in the consumption of furnace 10 and polluting gases (such as CO2 and NO). x The study also determined the increase in its efficiency, considering emissions and operating costs.

[0122] According to a feasible embodiment, the furnace 10 may include corresponding loading and unloading devices inside the chamber 13 corresponding to the inlet 11 and the outlet 12, so as to position the billet 200 from the feed roller 19 on the travel plane P, and to position the billet that will later self-enter the plane P on the extraction roller 21.

[0123] In particular, the loading device is configured to remove the billet 200 from the internal feed roller 19, thereby storing the billet on the first support elements 14, 15, while the unloading device is configured to remove the billet 200 from the last position in the furnace 10, thereby storing the billet on the internal extraction roller 21.

[0124] For loading and unloading equipment, there may be associated corresponding inert gas delivery equipment to form a vent seal corresponding to a slit provided on the wall of furnace 10, the slit being used for clamping and entry of moving elements of such equipment.

[0125] Within the heating chamber 13, the furnace 10 includes multiple heating and / or combustion components, or burners 43, distributed among different zones. The burners 43 are connected to a fuel source (e.g., methane) and a combustion-supporting source (e.g., air), preferably containing oxygen, via suitable fuel supply devices and combustion-supporting device (e.g., pipes).

[0126] According to some embodiments, the supply of combustion-supporting material and fuel within chamber 13 can be controlled and regulated in such a way that the combustion-supporting material is in a substoichiometric or stoichiometric ratio relative to the fuel, as described in the applicant's Italian patent application 102020000013285.

[0127] The burners 43 are organized into groups, each group comprising multiple burners 43 that are laterally aligned relative to the longitudinal extension of the furnace 10.

[0128] The burner 43 is associated with the upper wall 22, the rear end wall 25, and possibly the bottom wall 23.

[0129] The burner 43 is arranged above and below the traveling plane P. This arrangement of the burner 43 allows for limiting the length of the furnace 10 and obtaining uniform heating of the billet 200, which, as mentioned above, does not rotate about its own axis during movement due to its weight.

[0130] However, other configurations are also feasible.

[0131] See especially Figures 1-3 The first set of burners 43 is associated with the bottom wall 23 of the intermediate region B, the second set of burners 43 is associated with the upper wall 22, also in the intermediate region B, and two additional sets are arranged on the rear end wall 25, parallel to and across the travel plane P in the outlet region C.

[0132] Therefore, the furnace 10 of this invention has free sidewalls 26 and 27, that is, it is not equipped with a burner 43.

[0133] According to some embodiments, such as Figures 7-9 As shown, the furnace 10 is inserted into the apparatus 100 used for producing steel products.

[0134] The apparatus 100 may be configured differently depending on requirements, the type of energy available (gas, electricity) and / or where it is more convenient in the country of installation.

[0135] exist Figure 7 In the first configuration shown, the apparatus 100 includes a casting line 110, a furnace 10, and a rolling line 111 in the following order. In this case, the furnace 10 receives billets 200 directly from the continuous casting line at a temperature of approximately 850°C, heating them to a temperature of approximately 1050°C, so that they can have an initial rolling temperature of approximately 950°C-1000°C. Considering that the inlet temperature is already high, this allows the size of the furnace 10 to be determined with a limited length, and reduces the number of burners 43, which in this case exist only on the upper wall 22 of the intermediate region B and in the outlet region C.

[0136] This application is an alternative to using an induction furnace, and is used when there is a need for thrust balancing of a billet 200, for example, made of carbon steel, which has a reduced thermal gap between the surface and the core. Furthermore, the furnace 10 allows for buffering in the event of an interruption to the downstream rolling process due to an accident or cylinder change.

[0137] In the second construction, such as Figure 8As shown, apparatus 100 includes a storage area for semi-finished products 112, where billet 200 is at an ambient temperature of approximately 20°C. Downstream from furnace 10 are induction furnace 113 and rolling line 111. In this case, furnace 10 is sized to raise the billet 200 from an inlet temperature of approximately 20°C to an outlet temperature of approximately 850°C-950°C. This significantly reduces the oxide scale that begins to form at approximately 750°C, and also significantly reduces gas consumption and consequently emissions.

[0138] The induction furnace 113 heats the billet 200 to an initial rolling temperature of approximately 1150°C-1250°C. The second-structure furnace 10 of the apparatus 100 is already described in [reference needed]. Figures 1-3 The furnace described.

[0139] In the third construction, such as Figure 9 As shown, apparatus 100 includes a storage area for semi-finished products 112, where billets 200 are at an ambient temperature of approximately 20°C. The downstream furnace 10 is sized to raise the billets 200 from an inlet temperature of approximately 20°C to an outlet temperature of approximately 1050°C, allowing them to have an initial rolling temperature of approximately 950°C–1000°C at the inlet of rolling line 111. The furnace 10 of the third configuration of apparatus 100 has a greater length than the furnace 100 of the previous solution, a more extended heating zone B, and a larger number of burners 43 mounted on the bottom wall 23 and also on the upper wall 22.

[0140] according to Figures 10-11 In one variant shown, within the heating chamber 13, the furnace 10 includes an additional traveling plane P' arranged downstream of the traveling plane P in the direction of advance of the billet 200.

[0141] The other travel plane P' is of the movable sole type, making the furnace 10 a walking beam type in the first section, which includes an inlet region A, an intermediate region B, and an outlet region C, the outlet region in this case becoming an intermediate outlet region; and a walking hearth type in the second section, which defines the final outlet region D. In the second section, a higher heating temperature is allowed compared to the first section.

[0142] The characteristic of these two sections is that there is no system for cooling the components that constitute the corresponding travel planes P and P'.

[0143] Similar to the travel plane P, the other travel plane P' is also alternately defined by other fixed support elements 45 and other movable support elements 46, which are arranged to extend parallel to the length of the furnace 10, see... Figure 11 .

[0144] The other fixed support element 45 and movable support element 46 can be made of corresponding fire-resistant plates, which generally define a basically continuous plane.

[0145] The movable support element 46 is fixed to the same support frame 29 in a known and substantially similar manner to that previously described, such that the movement of the blank 200 occurs in a uniform and coordinated manner between the first and second sections.

[0146] exist Figures 10-11 In one embodiment, the support frame 29 includes a lower frame or lifting frame 29a that allows lifting movement and an upper frame or translation frame 29b that allows translational movement of the movable support elements 15, 46.

[0147] The upper frame 29b is slidably resting on the lower frame 29a.

[0148] The lower frame 29a moves up / down due to the moving device 30, which includes one or more inclined planes 47; one or more rolling elements 48 pivotally connected to the lower frame and sliding on the inclined planes; and one or more plugs 49 fixed to the lower frame 29a and fixed anchor points.

[0149] The rolling elements 48 are arranged in pairs, such that one rolling element slides on the inclined surface while the other rolling element slides to support the upper frame 29b.

[0150] The upper frame 29b slides horizontally on the lower frame 29a due to the moving device 30, which includes one or more additional plugs 51 fixed to the upper frame 29b and fixed anchor points.

[0151] Obviously, modifications and / or additions can be made to the apparatus for heating steel products as described above without departing from the scope and range of the present invention as defined in the claims.

[0152] In the following claims, references in parentheses are for ease of reading only and should not be considered as limiting factors regarding the scope of protection claimed in a particular claim.

Claims

1. A device (10) for heating steel products (200), characterized in that, include: - Heating chamber (13) extends between inlet (11) and outlet (12), and defines inlet region (A), intermediate region (B) and outlet region (C) in sequence inside. -The travel plane (P) in the heating chamber (13) is alternately defined by a fixed support element (14) and a movable support element (15) supported by a fixed support element (16) and a movable support element (17), respectively. - Feeding and extraction devices (18, 20) are provided with corresponding feed rollers (19) and extraction rollers (21) respectively associated with the inlet (11) and the outlet (12). - Heating and / or combustion components (43), which are arranged above and below the traveling plane (P), The fixed support element (14) and movable support element (15), the fixed support element (16) and movable support element (17), and the feed roller (19) present in the inlet region (A) are made of a first metal superalloy (M1); the fixed support element (14) and movable support element (15), the fixed support element (16) and movable support element (17) present in the intermediate region (B) are made of a second metal superalloy (M2); and the fixed support element (14) and movable support element (15), the fixed support element (16) and movable support element (17), and the extraction roller (21) present in the outlet region (C) are made of a third metal superalloy (M3). The first metal superalloy (M1), the second metal superalloy (M2), and the third metal superalloy (M3) comprise a combination of nickel and chromium as at least major components and other components between 10% and 30%, wherein nickel and chromium constitute at least 70% of their composition. Up to 90%, wherein the total nickel and chromium content of the first metal superalloy (M1) is lower than that of the second metal superalloy (M2), and the nickel and chromium content of the second metal superalloy (M2) is lower than that of the third metal superalloy (M3), wherein other chemical components that complete the chemical composition of the first metal superalloy (M1), the second metal superalloy (M2) and the third metal superalloy (M3) include at least one of aluminum, iron, carbon, tungsten, titanium, silicon, niobium, manganese and cobalt, or at least one of zirconium, vanadium, boron, phosphorus and molybdenum, or one of tantalum, magnesium and calcium, wherein the fixed support element (14) and the movable support element (15), the fixed support element (16) and the movable support element (17), and the feed roller (19) and the extraction roller (21) are manufactured using the first metal superalloy (M1), the second metal superalloy (M2) and the third metal superalloy (M3), allowing the absence of a liquid-based cooling system inside the heating chamber (13).

2. The apparatus (10) for heating steel products (200) according to claim 1, characterized in that, The movable support element (17) is manufactured to pass through the bottom wall (23) of the heating chamber (13) and is fixed to a single support frame (29) arranged below the bottom wall (23) and associated with the moving device (30).

3. The apparatus (10) for heating steel products (200) according to claim 2, characterized in that, The moving device (30) includes a plurality of moving units (31) and electromechanical equipment, each moving unit being provided with a connecting rod (32) adapted to allow proper movement of the support frame (29), and the electromechanical equipment being configured to move the connecting rod (32) directly or indirectly.

4. The apparatus (10) for heating steel products (200) according to claim 1, characterized in that, The device includes a lateral inlet (33) and a lateral outlet (34), both of which are associated with a corresponding closing unit (35), which is provided with a door (36) and a pantograph mechanism (37) for moving the door (36).

5. The apparatus (10) for heating steel products (200) according to claim 4, characterized in that, The closed unit (35) includes a plurality of inert gas delivery devices (42) associated with the inlet and outlet orifices (34, 35) and configured to create a gas barrier that prevents the atmosphere of the heating chamber (13) from being contaminated by outside air and prevents harmful gases from escaping from the heating chamber (13) itself.

6. The apparatus (10) for heating steel products (200) according to claim 1, characterized in that, The feed roller (19) and extraction roller (21) are arranged inside the heating chamber (13), passing through and suspended from the respective front and rear end walls (24, 25) of the heating chamber (13), wherein the feed and extraction devices (18, 20) include a plurality of additional inert gas delivery devices (44) configured to generate a vented seal for the feed roller (19) and extraction roller (21).

7. The apparatus (10) for heating steel products (200) according to claim 1, characterized in that, The device includes a loading device and an unloading device inside the chamber (13) corresponding to the inlet (11) and the outlet (12) respectively, to position the steel product (200) from the feed roller (19) on the travel plane (P) and from the travel plane (P) on the extraction roller (21).

8. The apparatus (10) for heating steel products (200) according to claim 1, characterized in that, The device includes an additional travel plane (P') arranged in the heating chamber (13) downstream of the travel plane (P) in the forward direction of the product (200), the additional travel plane (P') being alternately defined by additional fixed support elements (45) and additional movable support elements (46) made of corresponding fire-resistant plates.

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