Rod preheating from heat pool

Abstract

The invention relates to a preheating device for preheating rod-like, metal workpieces, wherein: the preheating device has a preheating chamber with a receiving region for receiving at least one workpiece; the preheating device has a heating fluid line through which a heating fluid can flow; the heating fluid can be heated by waste heat by means of a waste heat coupling unit comprised by the heating fluid line; the preheating device has a heat transfer fluid line through which a heat transfer fluid can flow; the preheating device comprises a heat transfer fluid heater which connects the heat transfer fluid line to the heating fluid line for heat conduction such that the heat transfer fluid can be heated by way of heat transfer from the heating fluid flowing in the heating fluid line; the heat transfer fluid line has a fluid output unit for outputting the heat transfer fluid into the receiving region such that a workpiece arranged in the receiving region is preheated indirectly by the heating fluid via the heat transfer fluid heated in the heat transfer fluid heater; the receiving region comprises a heating section for heating the workpiece; heat is transferred to the workpiece over a length of the heating section which corresponds to at least 0.7 times the workpiece.

Description

[0001] EXT-P-04597-WP2 - 1 - 09 / 18 / 2025

[0002] Rod preheating from heat pool

[0003] The invention relates to a device for preheating rod-shaped, metallic workpieces, in particular aluminum rods, by means of a heated fluid flow, which is heated in particular by waste heat from a manufacturing process and / or a factory facility, wherein the device has a preheating chamber for receiving the workpiece.

[0004] For example, a device for preheating rod-shaped workpieces is known from the prior art, as disclosed in EP 3 857 147 B1. The device disclosed therein uses heat from the exhaust gas of a gas rapid heating furnace to heat a heat transfer fluid and use this fluid to preheat the workpiece.

[0005] US Patent 4,373,706 discloses a device for preheating metallic workpieces, particularly those made of aluminum or magnesium, which has an electrically or fuel-heated preheating section. A disadvantage is stated to be that, in continuous operation with a workpiece being conveyed through the preheating section, the preheating section must be disproportionately long to ensure the desired preheating occurs over a sufficiently long residence time in the preheating section.

[0006] The invention is therefore based on the objective of proposing an improved preheating device which addresses the disadvantages of the prior art and in particular enables a compact design while simultaneously providing effective preheating.

[0007] This task is accomplished by the preheating device and the

[0008] Preheating system solved according to the independent claims. EXT-P-04597-WP2 - 2 - 18.09.2025

[0009] Advantageous embodiments of the preheating device according to the invention are the subject of the following description and description of figures as well as the dependent claims.

[0010] The features described and claimed in relation to the device shall also be deemed to be disclosed and claimable in accordance with the procedure.

[0011] The preheating device for preheating rod-shaped metallic workpieces, in particular aluminum rods, comprises a preheating chamber with a receiving area for at least one workpiece. It further comprises a heating fluid line through which a heating fluid can flow, and wherein the heating fluid can be heated by waste heat, preferably from a manufacturing process and / or factory equipment, by means of a waste heat coupling unit encompassed by the heating fluid line. The preheating device also comprises a heat transfer fluid line through which a heat transfer fluid can flow, and a heat transfer fluid heater, which thermally connects the heat transfer fluid line to the heating fluid line, so that the heat transfer fluid can be heated by heat transfer from the heating fluid flowing in the heating fluid line.The heat transfer fluid line has a fluid dispensing device for dispensing the heat transfer fluid into the receiving area, so that preheating of a workpiece arranged in the receiving area is carried out indirectly by the heating fluid via the heat transfer fluid heated in the heat transfer fluid heater.

[0012] According to the invention, the receiving area comprises a heating section for heating the workpiece, whereby heat transfer to the workpiece takes place over a length of the heating section which corresponds to at least 0.7 times, preferably two to four times, the maximum length of the workpiece, in particular EXT-P-04597-WP2 - 3 - 18.09.2025.

[0013] Preferably, a workpiece is moved through a preheating device according to the invention at a conveying speed that is preferably kept constant and is further advantageously adapted to other processing devices not included in the invention. The maximum length of a workpiece can be defined and / or specified by the entire preheating device and / or by subsequent or preceding processing devices not included in the invention and / or by industry standards. For example, a forming device following the heating of a workpiece can specify a maximum workpiece length. In an exemplary and common implementation of the preheating device, the maximum workpiece length is 1.5 m.

[0014] The present invention has demonstrated that, contrary to the prior art, sufficient preheating of the workpiece is achieved even with a heating section that is relatively short compared to the workpiece's length. A heating section length of just 0.7 times the workpiece's length is sufficient for adequate heating without requiring an excessively low conveying speed. A heating section length of two to four times the workpiece's length is particularly advantageous, as this, in combination with a typical and efficient conveying speed, results in a favorable dwell time in the heating section, leading to optimal workpiece heating.

[0015] Advantageously, the heat transfer fluid is formed from a liquid. This allows the wettability of a liquid, compared to a gas (EXT-P-04597-WP2 - 4 - 18.09.2025), which enables a corresponding residence or contact time of the liquid on the workpiece, to lead to a significant increase in the efficiency of heat transfer, thus allowing for a suitably short heating path.

[0016] Water has proven to be a particularly advantageous heat transfer fluid, both in terms of process handling and ease of availability. Due to its high specific heat capacity compared to other common liquids, water allows for the transfer of large quantities of heat.

[0017] In a first advantageous embodiment of the preheating device, the heat transfer fluid heater can include a heat exchanger for transferring heat from a first heating fluid, flowing in a first heating fluid line, to the heat transfer fluid. For example, the boiling point of the heat transfer fluid and / or other process-related boundary conditions can limit the operating temperature of the heat transfer fluid to a maximum value. A first heating fluid has a temperature above the operating temperature, so that a heat exchanger achieves advantageously simple heat transfer from the heating fluid to the heat transfer fluid. A first heating fluid can preferably be heated to a temperature above the operating temperature using waste heat from a manufacturing process and / or a factory facility. For example, waste heat from a combustion process, an electric heating process, and / or a metal melting process can be used.Particularly when waste heat from a combustion process is used, combustion exhaust gas can form a first heating fluid.

[0018] In an advantageous embodiment of the preheating device, the heat transfer fluid heater can include a heat pump unit for transferring heat from a second heating fluid, flowing in a second heating fluid line, to the heat transfer fluid. The second heating fluid has a temperature below the operating temperature of the heat transfer fluid, and the heat pump unit enables advantageously energy-efficient heat transfer from the second heating fluid to the heat transfer fluid. In this way, a multiple of the expended mechanical work can be utilized as heat for the heat transfer fluid. The second heating fluid can preferably be heated to a temperature below the operating temperature using waste heat from a manufacturing process and / or factory equipment.For example, waste heat can be used in cooling systems for metallic workpieces, compressed air compressors, hydraulic systems, cooling and / or deep-freeze systems, computer systems, air conditioning systems, foundries, solar thermal systems and / or anodizing systems.

[0019] The selection of a waste heat source should expressly not be limited to a narrow spatial and / or functional environment of the preheating device.

[0020] In an advantageously improved embodiment of the preheating device, the heat pump unit can be designed such that a heat quantity of 13 to 18 kWh, preferably 15 to 16 kWh, per ton of workpiece mass to be heated can be transferred from the second heating fluid to the heat transfer fluid, wherein the heat pump unit preferably has a

[0021] The heat pump control unit is designed to control the heating output of the heat pump system. Advantageously, such a heat pump system achieves a favorable ratio of heat output to input and / or costs for EXT-P-04597-WP2 - 6 - 18.09.2025

[0022] Acquisition and operation are particularly advantageous, achieving an optimum, especially from a business management perspective.

[0023] In a further advantageous embodiment of the preheating device, the fluid dispensing device can be arranged above the receiving area, wherein the fluid dispensing device has a dispensing opening for supplying the upper surface, and preferably the entire surface, of the workpiece with the heat transfer fluid. Particularly good results in heat transfer, combined with particularly economical operation of the preheating device, can be achieved with the heat transfer fluid, preferably water, exiting the fluid dispensing device, since, after the heat transfer fluid exits the fluid dispensing device, a surface of the workpiece is wetted by gravity if the fluid applied to the upper surface of the workpiece can spread over the entire surface of cylindrical workpieces solely by gravity.

[0024] In a further advantageous embodiment of the preheating device, the fluid dispensing device can extend parallel to a longitudinal axis of the receiving area in the preheating chamber, wherein the fluid dispensing device has a series of dispensing openings extending along the longitudinal axis of the receiving area to form a coating, preferably a laminar coating, with the heat transfer fluid on a top surface of the workpiece. This enables a particularly simple design of the preheating device while simultaneously ensuring the largest possible surface area of ​​the workpiece. The series of dispensing openings extending along the longitudinal axis of the receiving area (EXT-P-04597-WP2 - 7 - 18.09.2025) is also advantageous, as it ensures that sufficient heat can be discharged.

[0025] In a further advantageous embodiment of the preheating device, a heater bypass line with a valve assembly can be formed in the heating fluid line, whereby the heating fluid can be routed around the heat transfer fluid heater by means of the heater bypass line, thus reducing the heating of the heat transfer fluid. This advantageously makes it possible to stop, or at least reduce, the supply of heat to the heat transfer fluid heater and thus to the heat transfer fluid. In this way, overheating of the heat transfer fluid above the operating temperature or a predetermined maximum temperature is advantageously prevented.

[0026] Advantageously, the preheating device can include a control unit designed to interact with the valve assembly, allowing variable proportions of the heating fluid to be directed into the heat transfer fluid heater and / or the heater bypass line. This enables the heat transfer fluid to be heated up to a predefined maximum temperature. This allows for precise control of the amount of heat supplied to the heat transfer fluid heater, while minimizing operating effort. The control unit can be connected to a higher-level control unit via a data link, such as a fieldbus system, facilitating easy integration into a larger system.

[0027] In a further advantageous embodiment of the preheating device, the heat transfer fluid heater and the preheating chamber can be arranged in a heat transfer fluid circuit with a circulation pump device, wherein between the heat transfer fluid heater and the EXT-P-04597-WP2 - 8 - 18.09.2025

[0028] The preheating chamber contains a heat transfer fluid line, and a return line connects the preheating chamber to the heat transfer fluid heater. By using the heat transfer fluid in a closed loop, the costs for procuring the fluid can be significantly reduced through multiple heating cycles. For example, when using water as the heat transfer fluid, it is sufficient to compensate for water loss, particularly through evaporation. Even with the low cost of water, this results in a considerable cost advantage compared to the continuous use of fresh water. The use of a closed-loop heat transfer fluid system is also advantageous from an environmental perspective.

[0029] In a further advantageous embodiment of the preheating device, the heat transfer fluid circuit can include a treatment unit for the chemical treatment of the heat transfer fluid. This unit is designed to maintain a state of the heat transfer fluid in which the formation of deposits in the heat transfer fluid circuit is reduced, preferably prevented. Accompanying substances and / or impurities in the heat transfer fluid can accumulate in the heat transfer fluid circuit. Such deposits are known, for example, as so-called boiler scale when water is used as the heat transfer fluid. Furthermore, biological contamination is also possible, particularly in areas of the heat transfer fluid circuit with lower temperatures. Such deposits disrupt the operation of the preheating device and / or increase maintenance requirements, as they can impair the function of components of the heat transfer fluid circuit and / or damage them.This applies, for example, to valves, filters, nozzles, and / or pumps. Furthermore, deposits can block flow and increase resistance in pipes. The treatment unit EXT-P-04597-WP2 - 9 - 18.09.2025 can advantageously prevent maintenance costs for the preheating device by reducing such deposits. For example, the treatment unit can include a demineralization system.

[0030] In a further advantageous embodiment of the preheating device, a bypass line can be arranged parallel to the preheating chamber between the heat transfer fluid line and the return line. The bypass line and a supply line section connecting the heat transfer fluid line to the preheating chamber are each equipped with a shut-off valve. Advantageously, the bypass line makes it possible to heat at least a portion of the heat transfer fluid circulating through the bypass line and the heat transfer fluid heater, independent of whether a workpiece is supplied with the heat transfer fluid in the preheating chamber. Only after the heat transfer fluid has reached a defined target temperature can the workpiece in the preheating chamber be supplied with the heat transfer fluid by appropriately adjusting the shut-off valves.

[0031] In a further advantageous embodiment of the preheating device, a heat transfer fluid tank can be arranged between the preheating chamber and the return line, such that the heat transfer fluid discharged from the fluid dispensing device into the receiving area of ​​the preheating chamber flows from the preheating chamber into the heat transfer fluid tank and from the heat transfer fluid tank into the heat transfer fluid heater. The heat transfer fluid tank advantageously ensures continuous operation of the preheating device, in particular a continuous circulation of the heat transfer fluid within the preheating device. For example, the heat transfer fluid tank can compensate for fluctuating flow times of the heat transfer fluid through the preheating chamber EXT-P-04597-WP2 - 10 - 18.09.2025, which result from different workpiece shapes and / or from the advantageously pressureless and / or gravity-driven application of the heat transfer fluid to the workpiece.

[0032] In a further advantageous embodiment of the preheating device, the heat transfer fluid circuit can include a cleaning device, in particular a high-pressure cleaning device, wherein the cleaning device includes at least one additional fluid dispensing device for applying heat transfer fluid exiting from the additional fluid dispensing device to a surface of the workpiece.This embodiment advantageously enables the heat transfer fluid circuit and the heat transfer fluid contained therein to be used not only for preheating the workpiece but also for cleaning or pre-cleaning the workpiece, whereby, particularly advantageously, only a single or common heat transfer fluid circuit is required, and thus, the appropriately heated or preheated heat transfer fluid can also be used for cleaning or pre-cleaning the workpiece, thereby increasing the cleaning performance and further increasing, or at least preventing, the preheating of the workpiece.The contaminants to be removed can include, for example, dust, sand, grease, oils, but also more aggressive contaminants such as animal excrement, which are present on the surface of the workpiece due to manufacturing, storage and / or transport.

[0033] In a further advantageous embodiment of the preheating device, the heat transfer fluid circuit in the heat transfer fluid line EXT-P-04597-WP2 - 11 - 18.09.2025 can have a branch between the heat transfer fluid heater and the preheating chamber, whereby the heat transfer fluid is supplied to the cleaning device via this branch. This allows for particularly simple integration of the cleaning device into the preheating device. Preferably, the branch is designed as a valve device so that the branch is switchable and / or adjustable.

[0034] In a further advantageous embodiment of the preheating device, the cleaning unit can include a high-pressure pump configured to deliver the heat transfer fluid supplied to the cleaning unit to the additional fluid dispensing unit under increased pressure. The increased pressure of the high-pressure pump allows for a particularly intensive cleaning effect. High-pressure cleaning is especially advantageous because it eliminates the need for cleaning agents, such as surfactants. This significantly simplifies the treatment and disposal of the heat transfer fluid.

[0035] In a further advantageous embodiment of the preheating device, the cleaning device can include a collection device that collects the heat transfer fluid applied to the workpiece by the cleaning device and conveys it to the heat transfer fluid heater via the return line. This particularly advantageously allows the heat transfer fluid to be returned to the heat transfer fluid circuit after it has been applied to the surface of the workpiece as cleaning fluid. This enables the heat transfer fluid circuit to be operated as a closed loop without significant consumption; in particular, only a minimal amount of heat transfer fluid is removed from the heat transfer fluid circuit by using the cleaning device. EXT-P-04597-WP2 - 12 - 18.09.2025

[0036] The collection device is particularly advantageous when designed as a common collection device for the cleaning unit and the fluid dispensing unit and / or the preheating chamber. This simplifies the design of the heat transfer fluid circuit. In particular, the common collection device then ensures the return or transfer of the heat transfer fluid to a return line. In other words, the common collection device for the cleaning unit and the fluid dispensing unit or preheating chamber facilitates the return or merging of the different fluid paths of the heat transfer fluid circuit.

[0037] In a further advantageous embodiment of the preheating device, the heat transfer fluid line and / or return line can include filter media for filtering contaminants from the heat transfer fluid circuit.

[0038] This ensures that dirt or contaminant particles removed from the workpiece surface during pre-cleaning or cleaning with the cleaning device do not enter or remain in the heat transfer fluid circuit, nor do they cause wear or contamination of the components involved. Instead, such particles are filtered out of the heat transfer fluid circuit.

[0039] In a further advantageous embodiment of the preheating device, the preheating chamber can be tubular and designed as a continuous flow chamber with an inlet seal formed on a first end face and an outlet seal formed on an opposite end face. As a continuous flow chamber, the preheating device enables continuous operation, with workpieces being conveyed through the preheating device. This makes the preheating device particularly easy and functionally advantageous to integrate into a complete system. The seals, i.e., the inlet and outlet seals, can be designed as sliding seals, the opening of which is adapted to the respective cross-section, in particular diameter, of the workpiece, so that the seal, and especially the opening, rubs against the workpiece.

[0040] The invention further relates to a preheating system for preheating rod-shaped metallic workpieces, in particular aluminum rods, by means of a heated heat transfer fluid. The preheating system comprises at least one preheating device according to the invention, as described above, a waste heat source, and a rod-shaped metallic workpiece, in particular an aluminum rod.

[0041] In an advantageous embodiment of the preheating system, a first heating fluid line can be thermally connected to a first waste heat coupling unit, such that a first heating fluid flowing in the first heating fluid line can be heated to a first heating fluid temperature above the operating temperature of the heat transfer fluid by means of the first waste heat coupling unit using waste heat from a first waste heat source. Any manufacturing process and / or any factory equipment with a waste heat temperature above the operating temperature can be considered a first waste heat source. In other words, a coolant of any system and / or device that has a temperature level above the operating temperature can be used as the first heating fluid. A primary cooling circuit of an EXT-P-04597-WP2 - 14 - 18.09.2025

[0042] The system and / or device with a waste heat temperature above the operating temperature must be connected to the first heating fluid line, such that a primary coolant corresponds to the first heating fluid, or the primary cooling circuit can be thermally connected to the first heating fluid line. The first waste heat source can be, for example, a gas furnace, which is also intended for further heating of the workpieces after preheating. The exhaust gas from such a gas furnace typically has a temperature significantly above the operating temperature of the heat transfer fluid, enabling effective heating of the heat transfer fluid via a heat exchanger. A heat exchanger device can be provided for heat transfer directly from the exhaust gas to the heat transfer fluid, so that the exhaust gas can be considered the first heating fluid.This embodiment is particularly advantageous when the preheating device is in close proximity to the heat exchanger and the exhaust gas outlet of the gas furnace as a waste heat source.

[0043] When the preheating device and a waste heat source are located further away, the use of a dedicated heating fluid, especially a liquid, is advantageous because it simplifies pipe routing. Exhaust pipes, in particular, are very large in volume, making long pipe lengths disadvantageous. It is obvious that, in addition to a gas furnace, other waste heat sources can be used; for example, the coolant from an induction furnace and / or a metal melting furnace and / or a heat treatment plant can have a sufficiently high temperature. Technical and economic limitations are imposed, in particular, by heat loss along a heating fluid line and by its cost and / or complexity. EXT-P-04597-WP2 - 15 - 18.09.2025

[0044] In a further advantageous embodiment of the preheating system, a second heating fluid line can be thermally connected to a second waste heat coupling unit, such that a second heating fluid flowing in the second heating fluid line can be heated to a second heating fluid temperature below the operating temperature of the heat transfer fluid by means of the second waste heat coupling unit using waste heat from a second waste heat source. Any manufacturing process and / or any factory equipment with a waste heat temperature below the operating temperature can be considered the second waste heat source. In other words, a coolant from any system and / or device that has a temperature level below the operating temperature can be used as the second heating fluid.In this process, a primary cooling circuit of a system and / or device with a waste heat temperature below the operating temperature can be connected to the second heating fluid line, so that a primary coolant corresponds to the second heating fluid, or the primary cooling circuit can be thermally connected to the second heating fluid line. The waste heat from such sources can be used to heat the heat transfer fluid by means of a heat pump. A large number of machines and systems in a typical industrial plant generate waste heat at a temperature level below the operating temperature.

[0045] Heat transfer fluids. This waste heat can be used in the preheating system by means of the heat pump system.

[0046] A first heating fluid line and / or a second heating fluid line can each absorb waste heat from several waste heat sources and transfer it to the heat transfer fluid in the heat transfer fluid heater. A waste heat network can be configured. EXT-P-04597-WP2 - 16 - 18.09.2025

[0047] Further advantages, features and details of the invention are described below by way of example with reference to the schematic drawings. These show:

[0048] Figure 1: a schematic representation of a device according to the invention

[0049] Preheating device

[0050] Figure 2: a schematic and cut-out representation of a preheating system according to the invention.

[0051] Fig. 1 shows a preheating device 1 with a preheating chamber 2, which is designed as a continuous flow chamber. A workpiece 50, in this example an aluminum bar, is held in a receiving area 3 of the preheating chamber 2. The workpiece 50 rests on a conveyor 8, which conveys the workpiece 50 along a longitudinal axis L of the receiving area 3 through the preheating chamber 2. A heating section with length E is thus formed in the preheating chamber 2. In this example, the length E of the heating section corresponds to three times the length W of the workpiece 50.

[0052] Above workpiece 50, a line runs parallel to the longitudinal axis L.

[0053] Fluid dispensing device 5 with a plurality of dispensing openings 6, which are arranged along the longitudinal axis L on the fluid dispensing device 5. A heat transfer fluid 12 emerges from the dispensing openings 6, which in this exemplary embodiment is water. The dispensing of the heat transfer fluid 12 is shown by way of example at individual dispensing openings 6 in Fig. 1. The heat transfer fluid 12 comes into contact with a top surface 51 of the workpiece 50 and subsequently wets the surface of the workpiece 50. EXT-P-04597-WP2 - 17 - 18.09.2025

[0054] The fluid dispensing device 5 is thermally connected to a heat transfer fluid line 11, whereby the heat transfer fluid 12 is conveyed via the heat transfer fluid line 11 from a heat transfer fluid heater 13, in which it is heated to a working temperature, to the preheating chamber 2. The heat transfer fluid heater 13 thermally connects the heat transfer fluid line 11 to a heating fluid line in which a heating fluid flows. The heating fluid is heated by waste heat via a waste heat coupling unit. In the illustrated example, the heat transfer fluid heater 13 thermally connects a first heating fluid line 40a and a second heating fluid line 40b to the heat transfer fluid line 11.

[0055] In the illustrated embodiment, a first heating fluid flowing in a first heating fluid line 40a is heated to a temperature above the operating temperature by means of a first waste heat coupling unit 44a. A second heating fluid flowing in a second heating fluid line 40b is heated to a temperature below the operating temperature by means of a second waste heat coupling unit 44b.

[0056] The heat transfer fluid heater 13 includes a

[0057] Heat exchanger unit 14 and a heat pump unit 15.

[0058] The heat exchanger 14 is thermally connected to the first heating fluid line 40a, so that the heat transfer fluid 12 can be heated by the first heating fluid via the heat exchanger 14. The first heating fluid is heated by waste heat via the first waste heat coupling unit 44a. For the first heating fluid to reach a temperature above the operating temperature of the heat transfer fluid 12, the waste heat must be generated at a temperature level above the operating temperature of the heat transfer fluid 12. EXT-P-04597-WP2 - 18 - 18.09.2025

[0059] The heat pump unit 15 is thermally connected to a second heating fluid line 40b, so that the heat transfer fluid 12 can be heated by the second heating fluid via the heat pump unit 15. The second heating fluid is heated by waste heat via the second waste heat coupling unit 44b. The heat pump unit 15 makes it possible to use waste heat, which is generated at a temperature level below the operating temperature of the heat transfer fluid 12, to heat the heat transfer fluid 12. A heat pump controller 16 is provided for controlling the heat pump unit 15.

[0060] The invention is expressly not limited to a specific number of waste heat coupling units 44a, 44b; a plurality of waste heat coupling units 44a, 44b can be provided, such that a waste heat network is formed. This can be specifically adapted to an individual application, whereby a wide variety of waste heat sources can be used. A heating fluid line 40a, 40b can be designed as a circuit, so that the heating fluid circulates in the heating fluid line 40a, 40b. Alternatively, a

[0061] Heating fluid lines 40a and 40b should be designed as open lines, allowing the heating fluid to flow freely through the heat transfer fluid heater. This design is particularly advantageous when using exhaust gas as a heating fluid.

[0062] In the preheating chamber 2, a collection device 28 is arranged below the conveying device 8. This device collects the heat transfer fluid 12, discharges it from the preheating chamber 2, and returns it to the heat transfer fluid heater 13 via a return line 18. In this way, a heat transfer fluid circuit 10 is formed. EXT-P-04597-WP2 - 19 - 18.09.2025

[0063] The preheating chamber 2 has an inlet seal 33 on one inlet side, through which a workpiece 50 is introduced into the preheating chamber 2.

[0064] A cleaning unit 24 is connected to the preheating chamber 2. This cleaning unit incorporates a second fluid dispensing unit 25, through which the heat transfer fluid 12 is dispensed under increased pressure, thus cleaning the workpiece 50 by means of high pressure. For this purpose, a high-pressure pump 27 is connected to the heat transfer fluid line 11 via a branch line 26. The collection device 28 is designed to collect the heat transfer fluid 12 dispensed in the cleaning unit 24 and feed it into the return line 18. The workpiece 50 is discharged from the cleaning unit 24 through an outlet seal 34 and out of the preheating unit 1, making it ready for further processing.

[0065] A circulation pump unit 21 enables continuous circulation of the heat transfer fluid 12 in the heat transfer fluid circuit 10. A heat transfer fluid tank 20 provides a sufficiently large volume of the heat transfer fluid 12 to compensate for fluctuations in the flow rate in the heat transfer fluid line 11 and in the return line 18. A filter medium 23 removes impurities and particles, particularly those that enter the heat transfer fluid 12 in the cleaning unit 34. This protects other components of the heat transfer fluid circuit 10, such as the circulation pump unit 21, from the harmful effects of impurities and particles in the heat transfer fluid 12. EXT-P-04597-WP2 - 20 - 18.09.2025

[0066] Furthermore, the heat transfer fluid circuit 10 includes a treatment unit 19. In an alternative embodiment, a fresh water inlet can include the treatment unit. The treatment unit 19 treats the heat transfer fluid 12 in such a way as to prevent deposits from forming in the heat transfer fluid circuit 10. This applies, for example, to limescale deposits and / or so-called "boiler scale," which could impair or destroy the components of the heat transfer fluid circuit 10. The treatment can, for example, involve a chemical treatment to soften the heat transfer fluid 12.

[0067] A chamber bypass line 29 runs parallel to the preheating chamber 2, bypassing it. Shut-off valve devices 31, 32 in the chamber bypass line 29 and in a supply line section 30 of the heat transfer fluid line 11 determine the flow path of the heat transfer fluid 12.

[0068] The chamber bypass line 29 allows the heat transfer fluid 12 to circulate without flowing through the preheating chamber 2. This prevents the heat transfer fluid 12 from being discharged when no workpiece 50 is in the receiving area 3, and also allows for faster heating of the heat transfer fluid 12 when using the chamber bypass line 29.

[0069] To limit the heating of the heat transfer fluid 12, and in particular to prevent overheating of the heat transfer fluid 12 in the heat transfer fluid heater 13, heating fluid can be directed into heater bypass lines 42 by means of valve devices 43. Such overheating could occur, in particular, when more waste heat is transferred to the heat transfer fluid 12 via the heating fluid from a waste heat coupling unit 44a, 44b than from the EXT-P-04597-WP2 - 21 - 18.09.2025

[0070] Heat transfer fluid is delivered to a workpiece 50. The valve devices 43 are connected to a control unit 7 for control purposes.

[0071] Fig. 2 shows a schematic and cut-out representation of a preheating system 60 according to the invention with several waste heat sources 61a, 61b.

[0072] Three second waste heat coupling units 44b are formed as part of the preheating system 60 by means of a second heating fluid line 40b. These second waste heat coupling units 44b transfer waste heat Qb from second waste heat sources 61b to the heating fluid flowing in the second heating fluid line 40b. The waste heat Qb has a temperature level below the operating temperature of the heat transfer fluid 12 of the preheating device 1. This waste heat can, for example, originate from an air conditioning system, a refrigeration unit, a compressed air compressor, or a hydraulic system. The preheating system according to the invention is not limited to a specific type of waste heat source 61b.

[0073] By means of first heating fluid lines 40a, two first waste heat coupling units 44a are formed as part of the preheating system 60. These first waste heat coupling units 44a transfer waste heat Qa from first waste heat sources 61a to the heating fluid flowing in the first heating fluid line 40a. The waste heat Qa has a temperature level above the operating temperature of the heat transfer fluid 12 of the preheating device 1. For example, waste heat from a metal melting furnace can be transferred to the first heating fluid by means of a first waste heat coupling unit 44a and thus supplied to the preheating device 1. It is also possible, in a known manner, to use an exhaust gas stream from a gas furnace, EXT-P-04597-WP2 - 22 - 18.09.2025, in particular from a gas furnace, as the first heating fluid for further heating of the workpiece 50 after preheating. In this case, a first heating fluid line 40a is designed as the exhaust gas line of the gas furnace.

[0074] For operating conditions of the preheating system 60 in which the heat transfer fluid 12 has reached a maximum temperature such that no further waste heat Qa, Qb can be absorbed by the heat transfer fluid 12, a waste heat source 61a, 61b can be connected to an additional, conventional cooling system. This ensures that a waste heat source 61a, 61b is adequately cooled at all times and that the heat transfer fluid 12 and / or a heating fluid does not overheat. In a configuration with a gas furnace and direct heat transfer from an exhaust gas stream to the heat transfer fluid 12, an additional exhaust gas line can be provided, which discharges the exhaust gas without heating the heat transfer fluid 12.

[0075] Figure 2 shows that the preheating system 60 according to the invention is not limited to connecting several waste heat coupling units 44a, 44b via a common first heating fluid line 40a and a common second heating fluid line 40b. A plurality of heating fluid lines 40a, 40b can be formed, in which different fluids can also flow.

[0076] The preheating system 60 preferably forms a waste heat network, wherein waste heat Qa, Qb from various waste heat sources 61a, 61b is supplied to the preheating device 1 via the heating fluid lines 40a, 40b. There is no limitation to waste heat sources 61a, 61b in the immediate vicinity of the preheating device 1. The preheating system 60 can be flexibly adapted to a specific application and the waste heat sources 61a, 61b available therein. EXT-P-04597-WP2 - 23 - 18.09.2025

[0077] Reference sign

[0078] 1 Preheating device

[0079] 2 Preheating chamber

[0080] 3 Recording area

[0081] 5 Fluid dispensing device

[0082] 6. Output opening

[0083] 7 Control unit

[0084] 8 Support facility

[0085] 10 Heat transfer fluid circuit

[0086] 11 Heat transfer fluid line

[0087] 12 Heat transfer fluid

[0088] 13 heat transfer fluid heaters

[0089] 14 Heat exchanger unit

[0090] 15 Heat pump system

[0091] 16 Heat pump control unit

[0092] 18 Return line

[0093] 19 treatment facility

[0094] 20 Heat transfer fluid tank

[0095] 21 Circulation pump system

[0096] 23 filter media

[0097] 24 cleaning equipment

[0098] 25 Additional fluid dispensing device

[0099] 26 Junction

[0100] 27 High-pressure pump

[0101] 28 Containment device

[0102] 29 Chamber bypass line

[0103] 30 Supply line section

[0104] 31 Shut-off valve assembly

[0105] 32 Shut-off valve assembly EXT-P-04597-WP2 - 24 - 18.09.2025

[0106] 33 Entrance seal

[0107] 34 Outlet seal

[0108] 40 Heating fluid line a. First heating fluid line b. Second heating fluid line

[0109] 42 Heater bypass line

[0110] 43 Valve assembly

[0111] 44 Waste heat coupling unit a. First waste heat coupling unit b. Second waste heat coupling unit

[0112] 50 workpieces

[0113] 51 Top

[0114] 60 Preheating system

[0115] 61 Waste heat source a. First waste heat source b. Second waste heat source

[0116] L Longitudinal axis of the recording area

[0117] E Length of the heating section

[0118] W Length of the workpiece

[0119] Qa waste heat

[0120] Qb Waste heat

Claims

EXT-P-04597-WP2 18.09.2025 Patent claims 1. Preheating device (1) for preheating rod-shaped metallic workpieces (50), in particular aluminum rods, wherein the preheating device (1) has a preheating chamber (2) with a receiving area (3) for receiving at least one workpiece (50), wherein the preheating device (1) has a heating fluid line (40a, 40b) through which a heating fluid can flow, wherein the heating fluid is supplied by means of a Heating fluid line (40a, 40b) comprising waste heat coupling unit (44a, 44b) which can be heated by waste heat (Qa, Qb), preferably from a manufacturing process and / or a factory facility, wherein the preheating device (1) is a heat transfer fluid line (11) has a heat transfer fluid (12) through which a heat transfer fluid can flow, wherein the preheating device (1) has a heat transfer fluid heater (13) includes the Heat transfer fluid line (11) thermally conductive with the connects the heating fluid line (40a, 40b) so that the Heat transfer fluid (12) by heat transfer from the in the heating fluid line (40a, 40b) can be heated by flowing heating fluid, wherein the heat transfer fluid line (11) is a Fluid dispensing device (5) for dispensing the heat transfer fluid (12) into the receiving area (3), such that a workpiece (50) arranged in the receiving area (3) is preheated indirectly by the heating fluid via the heat transfer fluid heater (13). Heat transfer fluid (12) is applied, characterized by this, EXT-P-04597-WP2 18.09.2025 that the receiving area (3) comprises a heating section for heating the workpiece (50), wherein heat transfer to the workpiece (50) takes place over a length (E) of the heating section, which corresponds to at least 0.7 times, preferably two to four times, the length (W), in particular a maximum length (Wmax), of the workpiece (50).

2. Preheating device (1) according to claim 1, characterized in that the heat transfer fluid heater (13) comprises a heat exchanger device (14) for transferring heat from a first heating fluid to the heat transfer fluid (12).

3. Preheating device (1) according to claim 1 or 2, characterized in that the heat transfer fluid heater (13) comprises a heat pump device (15) for transferring heat from a second heating fluid to the heat transfer fluid (12).

4. Preheating device (1 ) according to one of claims 1 to 3, characterized in that the fluid dispensing device (5) is arranged above the receiving area (3), wherein the fluid dispensing device (5) has a dispensing opening (6) for supplying a top surface (52) and preferably for wetting the entire surface of the workpiece (50) with the heat transfer fluid (12).

5. Preheating device (1) according to one of claims 1 to 4, characterized in that, EXT-P-04597-WP2 - 3 - 18.09.2025 that the fluid dispensing device (5) extends parallel to a longitudinal axis (L) of the receiving area (3) in the preheating chamber (2), wherein the fluid dispensing device (5) has a series of dispensing openings (6) extending along the longitudinal axis (L) of the receiving area (3) for forming a wetting, preferably a laminar wetting, with the heat transfer fluid (12) on a top surface (52) of the workpiece (50).

6. Preheating device (1) according to one of claims 1 to 5, characterized in that a heating fluid line (40a, 40b) is provided in the heating fluid line. The heater bypass line (42) is equipped with a valve device (43), wherein heating fluid can be routed past the heat transfer fluid heater (13) by means of the heater bypass line (42), so that a reduced heating of the heat transfer fluid (12) takes place.

7. Preheating device (1) according to claim 6, characterized in that the preheating device (1) comprises a control device (7) which is configured for control-related interaction with the valve device (43) so that the heating fluid can be directed to the heat transfer fluid heater (13) and / or to the heater bypass line (42) in variable proportions, so that the heating of the heat transfer fluid (12) takes place up to a predefined maximum temperature.

8. Preheating device (1) according to one of claims 1 to 7, characterized in that, EXT-P-04597-WP2 - 4 - 18.09.2025 that the heat transfer fluid heater (13) and the preheating chamber (2) are arranged in a heat transfer fluid circuit (10) with a circulation pump device (21), wherein the heat transfer fluid line (11) is formed between the heat transfer fluid heater (13) and the preheating chamber (2), and a return line (18) is formed between the preheating chamber (2) and the heat transfer fluid heater (13).

9. Preheating device (1) according to claim 8, characterized in that the heat transfer fluid circuit (10) comprises a treatment device (19) for the chemical treatment of the heat transfer fluid (12), which is designed to maintain a state of the heat transfer fluid (12) in which the formation of deposits in the heat transfer fluid circuit (10) is reduced, preferably prevented.

10. Preheating device (1 ) according to claim 8 or 9, characterized in that a chamber bypass line (29) is arranged parallel to the preheating chamber (2) between the heat transfer fluid line (11 ) and the return line (18), wherein the chamber bypass line (29) and a supply line section (30) connecting the heat transfer fluid line (11 ) to the preheating chamber (2) are each provided with a shut-off valve device (31 , 32).

11. Preheating device (1) according to one of claims 8 to 10, characterized in that a heat transfer fluid tank (20) is arranged between the preheating chamber (2) and the return line (18), such that the EXT-P-04597-WP2 - 5 - 18.09.2025 from the fluid dispensing device (5) into the receiving area (3) of the preheating chamber (2) heat transfer fluid (12) from the preheating chamber (2) into the heat transfer fluid tank (20) and from the heat transfer fluid tank (20) into the heat transfer fluid heater (13).

12. Preheating device (1) according to one of claims 8 to 11, characterized in that the heat transfer fluid circuit (10) comprises a cleaning device (24), in particular a high-pressure cleaning device, wherein the cleaning device (24) comprises at least one additional fluid dispensing device (25) for applying heat transfer fluid (12) exiting from the additional fluid dispensing device (25) to a surface (52) of the workpiece (50).

13. Preheating device (1) according to claim 12, characterized in that the heat transfer fluid circuit (10) in the heat transfer fluid line (11) between the heat transfer fluid heater (13) and the preheating chamber (2) has a branch (26), wherein the heat transfer fluid (12) is supplied to the cleaning device (24) by means of the branch (26).

14. Preheating device (1 ) according to claim 12 or 13, characterized in that the cleaning device (24) comprises a high-pressure pump (27) which is configured to pump the heat transfer fluid (12) supplied to the cleaning device (24) under increased pressure to the additional fluid dispensing device (25). EXT-P-04597-WP2 - 6 - 09 / 18 / 2025 15. Preheating device (1) according to one of claims 12 to 14, characterized in that the cleaning device (24) comprises a collecting device (28) which collects the heat transfer fluid (12) applied to the workpiece (50) by the cleaning device (24) and directs it to the heat transfer fluid heater (13) by means of the return line (18).

16. Preheating device (1) according to one of claims 8 to 15, characterized in that the heat transfer fluid line (11 ) and / or return line (18) comprises filter media (23) for filtering contaminants from the heat transfer fluid circuit (10).

17. Preheating device (1 ) according to one of claims 1 to 16, characterized in that the preheating chamber (2) is tubular and designed as a flow chamber with an inlet seal (33) formed on a first end face and an outlet seal (34) formed on an opposite end face.

18. Preheating system (60) for preheating rod-shaped metallic workpieces, in particular aluminium rods, by means of a heated heat transfer fluid (12), at least comprising a preheating device (1 ) according to one of claims 1 to 17, a waste heat source (61 ) and a rod-shaped metallic workpiece (50), in particular an aluminium rod (51 ).

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