Control apparatus for a melting furnace and melting furnace

Abstract

The invention relates to a control apparatus for operating a melting furnace, in particular for melting metals and / or metal components, wherein the melting furnace has at least one fuel-operated heating device and at least one electric heating device for heating at least one melting chamber of the melting furnace; and wherein the control apparatus is configured to set a ratio of the energy input of the at least one fuel-operated heating device to the energy input of the at least one electric heating device into the melting chamber.

Description

[0001] BORBET GmbH August 2025

[0002] 220815PC

[0003] Control device for a melting furnace and melting furnace

[0004] The disclosure relates to a control device for a melting furnace and a melting furnace.

[0005] Melting furnaces are used in industrial settings for melting metals such as aluminum, copper, etc. The metal is fed into a heated melting chamber or heating chamber and melted there. This metal can include scrap metal, preferably ingots, shavings, and / or even scrap components like vehicle wheels. It is placed in a defined area within the melting chamber and can then flow into the molten metal after melting.

[0006] Various technologies are currently used to heat the melting chamber. For example, there are melting furnaces that are heated with fossil fuels such as gas, such as natural gas. There are also melting furnaces with electric heating elements for heating the melting chamber. The use of hydrogen as a fuel for melting furnaces is also known.

[0007] Melting furnaces are known, for example, from DE 10 2014 010 820.1.

[0008] The framework for the use of melting furnaces is dynamic due to the increasing focus on energy security and environmental protection. This concerns, on the one hand, changing electricity and fuel prices, and on the other hand, environmental regulations and emission limits for such plants.

[0009] It is therefore the purpose of the present disclosure to provide a control system (or control device) for a melting furnace and a melting furnace with such a control system that enables flexible operation of the energy sources used.

[0010] The problem is solved by the patent claims, with preferred options or further developments described in the dependent patent claims.

[0011] The control device as disclosed is for the operation of a melting furnace BORBET GmbH August 2025

[0012] 220815PC is intended, in particular, for melting metals and / or metallic components. The melting furnace may have at least one fuel heating device and at least one electric heating device for heating at least one melting chamber of the melting furnace. It should be noted here that, in principle, any type of melting furnace or melting furnace design can be included, and that the heating devices are also commonly referred to as "burners" or the heating devices may include such burners. Furthermore, the term "melting furnace" described here can also refer to other furnaces, such as heat treatment furnaces or afterburners.

[0013] The melting furnace is used, for example, to melt metal parts, such as aluminum scrap or other metals like copper. These are fed into the melting chamber and melted there. For example, the metal parts are arranged in a first chamber and from there conveyed through an opening into the melting chamber for melting.

[0014] The melting furnace preferably has at least two different heating devices, most preferably at least one fuel-fired heating device and at least one electric heating device. For the fuel-fired heating device, the fuel can be, for example, natural gas, propane, butane, isobutane, hydrogen, oil, wood, coal, and the like. The electric heating device comprises, for example, electric arcs, induction heating elements, electric resistance heating elements (or heating), and the like for generating heat. These heating devices include or are burners of a type already known, both electrically and fuel-fired.

[0015] To heat the melting chamber, the fuel heating device and the electric heating device can be used to heat parts of the melting chamber directly, as well as to heat gas that is passed through or around the burners, for example air, oxygen, nitrogen, etc., which is then introduced into the melting chamber by the heating device in the heated state.

[0016] The control device can be configured to determine a ratio between the energy input of the at least one fuel-fired heating device and the energy input. BORBET GmbH August 2025

[0017] 220815PC to adjust at least one electric heating device in the melting chamber. For example, given a predetermined target value for total energy input or a predetermined melting capacity of the melting furnace, the energy input of the multiple heating devices can be controlled, adjusted, or regulated in such a way that the sum of the heating devices provides the total energy input to the melting chamber, i.e., that the sum of the respective / individual energy inputs of the heating devices results in the predetermined target value for the total energy input or the melting capacity.

[0018] The ratio of energy inputs from each heating element can be regulated, set, or controlled by the control device. For example, with two heating elements, the control device can set a ratio of 2:1, 0:1, 1:0, 1:2, 1:3, 3:1, etc., between the energy input of a fuel-fired heating element and the energy input of an electric heating element. Alternatively or additionally, the control device can also be configured to set / control (absolute) proportions; for example, 40% energy input from a fuel-fired heating element and 60% energy input from an electric heating element, each relative to a desired total energy input.

[0019] Furthermore, it is noteworthy that the control / setting by the control device can be configured according to various possible options. For example, the control device can periodically and / or event-drivenly change the (target) ratio or the (target) proportions of the energy inputs from the various heating devices. Periodic control would mean, for example, that the control device changes / sets the target at certain regular or irregular time intervals, while event-driven control could trigger a change, for example, when a new melting process is started, or when certain framework parameters change, such as the availability or price of electricity or fuel, etc. A suitable control system can, for example, check the target ratio or proportions at intervals of half an hour or a few minutes and adjust / change / reset them as necessary.

[0020] With regard to the energy input, it should be noted that this can be detected or determined in various previously known ways, and each of these possible implementations is intended to be covered by this disclosure. For example, the control device may include a module (hardware and / or software) that BORBET GmbH August 2025

[0021] 220815PC

[0022] Energy input is calculated and / or simulated based on physical relationships. This can be done, for example, by knowing the physical and structural characteristics of the heating device and using a mathematical-physical model to calculate the energy input, where, for example, the fuel input, e.g., in the form of its gas mass flow rate or the like, and / or the gas mass flow rate, e.g., of the combustion air supplied to the heating device, preferably per unit of time, can be used as control variables. Thus, for example, if the required energy input of the fuel-fired heating device is X MW or X MWh – it is noteworthy that the energy input of the heating device into the melting chamber can preferably be a quantity of heat or a (heating) output – the control device or its corresponding module can calculate and / or simulate that a fuel mass or fuel mass flow rate (i.e.,The quantity of fuel (per unit of time) required to be supplied to the fuel heating device from a fuel source applies. The same applies to the electric heating device, except that instead of fuel, electrical current is supplied to provide the required energy input to the melting chamber. Instead of a calculation or simulation, a lookup table, an artificial intelligence (AI) trained with real test operating data, and / or other known implementations of such a control system can be used as an alternative or additional method.

[0023] For example, the control device can regulate / adjust the energy input into the melting chamber of each heating element by controlling the supply (quantity, power) of electrical current and the supply of fuel (quantity or time) to the various heating elements, and thus also control / regulate / adjust the ratio between these elements; specifically, in such a way that the target value for the ratio or proportions is achieved. The achievement of the control targets can be monitored and controlled as known, e.g., with PID control or similar methods. Further control parameters may also be present; for example, the fuel / electricity supply can be used with a fixed gas / air supply, but the gas / air supply can also be adjustable, so that both the fuel / electricity supply and the gas / air supply to the heating elements can be control parameters for controlling the energy input into the melting chamber.

[0024] In other words, the control device can be configured to set the (control target) ratio (or its value(s)) and the (individual) BORBET GmbH August 2025

[0025] 220815PC

[0026] To regulate the energy inputs of the respective heating devices accordingly, i.e., so that the ratio is achieved and maintained.

[0027] The control device, as disclosed, allows for a highly flexible response to external conditions. For example, if more electricity from renewable energy sources is available, the electrical output can be increased and the proportion of fuel, such as natural gas, reduced. This allows the CO2 emissions of the melting furnace to be flexibly reduced while maintaining the same furnace output. This is advantageous with regard to environmental goals and can be helpful in meeting emission targets. A further advantage arises in the dynamic environment of electricity, fossil fuel costs, and hydrogen prices. For instance, if electricity prices rise, the proportion of fossil fuel, such as natural gas, can simply be increased. This enables particularly economical operation of the melting furnace under changing conditions. The same applies to fluctuating electricity and fuel availability.This ensures continuous economical operation of the melting furnace, even if there are bottlenecks regarding the availability of electricity or fuel.

[0028] The control device can also be designed as a software program product or as a hardware and / or software device. As a software program product, the device could be designed as program code or at least contain such code that can be stored in memory and executed by a computer / processor.

[0029] Furthermore, the control device can be configured to control the energy input of the at least one fuel heating device and the at least one electric heating device into the melting chamber in such a way that the sum of the energy inputs by the fuel heating device and the electric heating device corresponds to a (preset) total energy input target value.

[0030] In other words, the control device can not only regulate the energy input of the respective heating elements. The control device can also set and regulate the total energy input into the melting chamber or the melting capacity, or implement its fulfillment, for example, by specifying a target total energy input value or a corresponding profile that is maintained over the melting time. BORBET GmbH August 2025

[0031] The 220815PC encompasses different total energy input target values ​​and monitors compliance with these, for example, through PID control or similar methods. The total energy input is the sum of the energy inputs from the (active) heating devices. The total energy input target value(s) can be manually entered by a furnace operator on a control PC or similar device, or they can be programmed into the control device and stored in memory. For example, different values ​​can be stored for different masses of material to be melted and / or its composition and / or other parameters.

[0032] The preferred design allows for comprehensive and also partially or fully automated control / regulation of the entire melting process, also with regard to the boundary conditions already discussed above concerning environmental regulations, availability, etc.

[0033] Furthermore, the control device can be configured to adjust the ratio of the energy inputs from at least one fuel heating device and at least one electric heating device in such a way that the operating costs of the melting furnace are minimized, at least comprehensively, to the sum of the electricity price and the fuel price.

[0034] The control device can include an internet interface, allowing it to retrieve, for example, current daily prices from a power exchange, available electricity or fuel supply capacities, fuel delivery prices, and electricity purchase prices, including those from different suppliers. Fixed prices and suppliers for fuel and electricity can be stored in the control system and updated automatically via internet access or manually by operator input at a control terminal.

[0035] Similarly, legal frameworks, such as purchase obligations, emission limits, and the like, can be stored in the control system and integrated into the control of the melting furnace for the aforementioned purposes. The goal is stable and economical operation of the melting furnace. For example, if instabilities have occurred or are expected in a supplier's power grid that affect the stable operation of the melting furnace and thus negatively impact product quality, this can be reflected in the control system and taken into account in the control of the BORBET GmbH August 2025

[0036] 220815PC

[0037] Melting furnaces, for example, are also taken into account. For instance, a stable fuel supply with gas may be advantageous compared to electricity as an energy carrier, which is more energy-efficient but unstable.

[0038] Alternatively or additionally, the control device can also include a load shedding signal or a corresponding control mechanism. Specifically, the control regarding power consumption, e.g., from the public grid, can be linked to a load shedding signal to prevent exceeding the agreed power consumption per unit of time.

[0039] The control device can be configured to adjust the ratio of the energy inputs of at least one fuel heating device and at least one electric heating device in such a way that a predetermined maximum emission value of the melting furnace is not exceeded or an emission value is minimized, in particular that a predetermined CO2 emission value is not exceeded or a CO2 emission value is minimized.

[0040] For example, a new maximum emission limit prescribed by law may necessitate adjustments to the operation of the melting furnace. This can then be achieved by drawing on empirical data, such as that stored in the control system, and by setting a specific ratio of fuel calorific value supplied per unit of time per unit of electricity supplied, so that the pollutant limit, for example the CO2 emission limit, is met.

[0041] Similarly, a sensor, for example a CO2 sensor, in the exhaust pipe of the melting furnace can determine the emission value and, depending on the determined emission value, for example CO2 output, adjust the ratio of fuel supplied to electricity as needed, for example reducing it if the emission value is exceeded. This adjustment or control process can be continuous or event-driven, for example at specific time intervals.

[0042] The control device may include an artificial intelligence (AI) control module that features a trained artificial intelligence (AI), and the AI ​​control module may be configured to determine the ratio of the individual energy inputs of the least one BORBET GmbH August 2025

[0043] 220815PC

[0044] The control device is designed to select the fuel-fired heating system and at least one electric heating system as the control target. The computer was trained using simulated or real values ​​from comparable or identical systems.

[0045] The control system can access a knowledge base of the control system or retrieve information via an internet interface. For example, the control system can collect information on measured emission values, fuels used, and electricity consumed, correlate this data, and incorporate it into the definition of the control objective. Regarding the electricity used, the control system can build a knowledge base concerning the frequency of fluctuations by an electricity supplier, such as the frequency of voltage fluctuations below a specific voltage value within a given period, and thus define a quality rating for the electricity. This quality rating can then be considered in relation to the control objective, for example, by upgrading or downgrading electricity of a specific origin with regard to the manufacturer or production method when used in the control objective.

[0046] The control device may include a rule-based control module configured to set the ratio of the individual energy inputs of the at least one fuel heating device and the at least one electric heating device as the control target of the control device.

[0047] For example, a knowledge base is stored in the rule-based control module. A rule of the rule-based control module might look like this: if the mains current fluctuations of the used current exceed a specific voltage range within a defined time interval, increase the ratio between the energy input of the fuel heating device and the energy input of the electric heating device into the melting chamber.

[0048] Another rule of the rule-based control module could, for example, look like this: if the CO2 emissions in the exhaust pipe exceed a specific value, a predefined time, or a predefined number of times within a defined time interval, reduce the ratio between the energy input of the fuel heating device and the energy input of the electric heating device into the melting chamber.

[0049] For example, the control device regulates the energy input into the melting chamber. BORBET GmbH August 2025

[0050] 220815PC such that the control device regulates the fuel supply to the fuel-fired heating device and the power supply to the electric heating device. This fundamentally allows the ratio between the fuel supply of the fuel-fired heating device and the power consumption of the electric heating device to be flexibly adjusted and specifically adapted to targets for pollutant emissions, e.g. CO2 emissions, power consumption, and safe operation.

[0051] The control device can be configured to control a supply of reducing gas to the melting chamber, preferably based on measurement results from at least one sensor in the melting chamber for detecting oxidative gas components.

[0052] The reducing gas can decrease the oxidation of the metal being melted in the furnace, thereby improving product quality. Suitable reducing gases include carbon monoxide, hydrogen, natural gas, coke oven gas, and mixtures thereof. Monitoring the oxidizing gas content with a sensor in the melting chamber allows for a controlled and adjusted supply of reducing gas based on the gas composition within the chamber, thus optimizing the gas composition and improving product quality.

[0053] For example, the control device is designed to supply hot gas from the afterburned exhaust gas of the melting chamber to at least one fuel heating device.

[0054] This allows for a reduction in the energy consumption and pollutant emissions of the melting furnace. For example, a valve or flap can be installed in the exhaust pipe, enabling the temporary recirculation of post-combusted exhaust gas to the fuel-heating unit as needed. The control system for this type of exhaust gas recirculation can be coupled with a sensor in the exhaust pipe, for example, for oxygen, carbon monoxide, carbon dioxide, or nitrogen oxides (NOx), to allow for specific combustion control. The temperature of the exhaust gas in the exhaust pipe can also be measured using a sensor. An optional temperature sensor can also be used to control the energy input(s), thus regulating the achievement of desired energy inputs. BORBET GmbH August 2025

[0055] 220815PC

[0056] The control device can be configured to adjust an exhaust gas mass flow from the melting chamber based on the proportion of energy input by the fewest fuel heating devices in relation to the total energy input.

[0057] This allows for particularly efficient control over the amount of pollutant emissions from the melting furnace and its fuel consumption. Furthermore, the exhaust gas mass flow rate can be easily measured by a sensor, for example, on the exhaust pipe.

[0058] According to one aspect of the disclosure, a melting furnace comprises at least one melting chamber, several heating devices for heating the melting chamber, and a control device as described above. The several heating devices include at least one fuel heating device and at least one electrical heating device for heating the melting chamber of the melting furnace.

[0059] It is in line with the present disclosure that the features described in the disclosure with regard to the process can be combined with the features set forth with regard to the melting furnace. The described melting furnace thus enables flexible heating of its melting chamber by means of at least one fuel heating device and at least one electric heating device. Depending on the objectives already discussed in detail above, a desired heating output for the melting chamber can be flexibly achieved from a portion of the heating output of the fuel heating device and a portion of the heating output of the electric heating device.

[0060] The fuel heating system is designed, for example, as a gas burner, specifically for natural gas, hydrogen, propane, butane, isobutane, mixtures of the aforementioned gases, or other gases or gas mixtures. Different fuel heating systems can also be combined, for example, burners for natural gas and hydrogen. The combination of various fuel heating systems allows for particularly flexible use of the melting furnace with regard to fuels. This enables a rapid response to fuel availability and other changing conditions, such as prices or legal regulations. BORBET GmbH August 2025

[0061] 220815PC

[0062] The electric heating device of the melting furnace can be connected to one or more power sources, which may include: the power grid and / or directly connected power generators, including PV systems, wind turbines, hydroelectric power plants and / or biogas power plants.

[0063] The flexible heating output of the melting furnace allows for a highly adaptable response to the characteristics of the available electrical power supply. For example, periods of weak electricity supply from renewable energy sources, such as wind power during periods of low wind, and thus a potentially lower heating output from the electric heating system, can be compensated for by increasing the heating output of the fuel-fired heating system. Furthermore, a fixed-price component can be implemented using direct generators or on-site connected power sources, such as photovoltaic arrays.

[0064] The electric heating device can have heating channels for passing gas or air, in which at least one ceramic tube is provided on the outside with induction coils, by means of which high-temperature resistant, oxidation-resistant ceramic or metal elements arranged inside the tube, between which the gas to be heated can flow, can be inductively heated.

[0065] This type of electric heating device offers the advantages of high operational reliability, rapid heating, and high energy efficiency. Furthermore, it can be implemented in a space-saving manner, even in small installation areas.

[0066] The melting furnace can further comprise at least one recirculation line for releasing gas from the melting chamber and recirculating the released gas to the multiple heating devices, wherein the recirculation line preferably comprises a supply line for fresh gas, for example ambient air, nitrogen, reducing gas, or the like, and / or a supply line for post-combustion gas. Fresh gas can also be introduced via the fresh gas supply to start the melting process when the melting furnace is being started up.

[0067] By recirculating the gas, the heating equipment can be heated with the recirculated warm gas from the melting chamber. For example, gas supplied to the fuel heating system is heated with the recirculated gas. BORBET GmbH August 2025

[0068] The 220815PC can improve the energy efficiency of the melting furnace.

[0069] For example, the melting furnace further comprises an exhaust gas device for venting gas from the melting chamber, preferably comprising an afterburner whose outlet may be connected to the recirculation line and / or a CO2 sensor for detecting the CO2 content in the exhaust gas, and / or at least one sensor for detecting the gas composition in the melting chamber, wherein a signal line is provided between sensors and control device, via which sensor readings are transmitted to the control device.

[0070] By using the afterburner and feeding its fuel gas into the recirculation line, emissions from the fuel heating system and thus from the melting furnace as a whole can be reduced. Furthermore, this improves the energy efficiency of the melting furnace. The sensor for measuring the gas composition in the melting chamber allows the control system to adapt to the current operating state of the melting furnace, resulting in optimized operation with reduced emissions and lower energy consumption.

[0071] The revelation is described below using an example with reference to the attached schematic drawing. It shows:

[0072] Fig. 1 shows the melting furnace according to a first embodiment in a schematic representation.

[0073] The following section describes an example in detail with reference to the figure. However, this is not intended to limit the description to the example described; rather, the described object can also include combinations of features from the embodiments described above.

[0074] Fig. 1 shows a schematic representation of the melting furnace 1 according to a first embodiment as disclosed in the disclosure. In this embodiment, the melting furnace 1 has a melting chamber 7, a fuel heating device 3, and an electric heating device 5 for heating the melting chamber 7 of the melting furnace 1. BORBET GmbH August 2025

[0075] 220815PC

[0076] An electrical power source E is represented as a black dot with a thick, dashed arrow connected to the electric heating device 5, thus schematically illustrating the power supply. It should be noted that this representation can also encompass multiple sources, such as a connection to the power grid and / or other power sources, like direct generators. Similarly, a fuel source B is represented as a black dot with a dashed arrow connected to the fuel heating device 3. Again, this schematic representation can depict one or more fuel sources.

[0077] The melting material SG is schematically represented as a pentagon in the lower right of melting chamber 7. Arrows indicate the energy input QB from the fuel heating unit 3 into the melting material SG and the energy input QE from the electric heating unit 5 into the melting material SG. The number of arrows and their further representation do not necessarily imply any conclusions about quantity, direction of input, or the like. In an example with two heating units / burners, the total energy input could be QB + QE.

[0078] In a further option, a sensor 9 can be provided in the melting chamber 7 to detect the oxidative gas content of the melting chamber "air" (the gas composition in the melting chamber). Additionally or alternatively, a sensor 9 can be provided to detect other values, for example, the CO, CO2, or NOx levels. Additionally or alternatively, in this embodiment, a CO2 sensor 11 is provided to detect the CO2 content in the exhaust gas. The sensor 11 can also be configured to detect other values, for example, the CO, CO2, or NOx levels.

[0079] According to a preferred modification of the embodiment, a recirculation line 13 is provided for releasing gas from the melting chamber 7 and recirculating the released gas to the several heating devices 3, 5. The recirculation line 13 can also have a supply line for fresh gas, for example, ambient air, nitrogen, reducing gas, or the like. In this embodiment, the recirculation line 13 is equipped with a compressor V for compressing the gases transported by the recirculation line 13.

[0080] An exhaust gas aftertreatment device 12 enables the aftertreatment of the combustion gases that can be released from the melting furnace 7, whereby they are cleaned by mechanical, catalytic, or chemical means. BORBET GmbH August 2025

[0081] 220815PC

[0082] Afterburning can be carried out here, so that this gas can then be fed back into the gas circuit via the cross-connection line shown in the figure, to the recirculation line 13. One of the sensors, as described above, can also be installed here to, for example, detect the gas composition or individual components of the exhaust gas.

[0083] On the left of the image is a control device 10, which, at least schematically, comprises one or more processors 10a and one or more memory units 10b. The memory unit 10b can comprise software and / or hardware modules whose computer program code the processor 10a can execute.

[0084] For example, the configuration is used to perform the required control / regulation / settings of the melting furnace components. The control device 10 can be part of the melting furnace or be arranged remotely and connected to it via internet or other data network connections.

[0085] The preferred, claimed control module(s) and the like may also be stored in data centers or cloud storage, which the processor 10a accesses. The dashed lines, which are not further marked with reference symbols and are not partially withdrawn to the control device 10 for the sake of clarity (i.e., they are broken off), indicate the control-related connection of the control unit 10 to the fuel heating device 3, the electric heating device 5, the sensor 9 on the melting chamber, the sensor 11 on the exhaust pipe, and the compressor V, as well as other possible devices to be controlled. These connections may be physical or wireless / radio-based.

[0086] Furthermore, the control device 10 is connected to control valves Kl to K7 via control lines that open or close gas passages in order to actuate them or monitor their position, which is also shown with dashed lines. The control valves Kl to K7 can also be other actuators or control elements with which a gas flow can be controlled. BORBET GmbH August 2025

[0087] 220815PC

[0088] Specifically, it should be mentioned that the K6 and K7 are intended to control the gas flow from a gas supply line into the heating devices 3 and 5, so that the energy input of the heating devices 3, 5 into the melting chamber 11 can be controlled via these and / or the fuel / electricity supply, including their ratio, etc.

[0089] The flap K5 can also introduce fresh gas, such as ambient air or other gases, so that the gas composition flowing to the heating devices 3,5 can be controlled via the control device 10 and preferably based on measured values ​​from the sensors described above, e.g. to reduce the proportion of oxidizing gases in the gas moved via the recirculation line 13 when easily oxidizing metals are melted.

[0090] Furthermore, device K4 serves to control the mass flow of recirculated gas from melting chamber 11 back to heating devices 3 and 5. This "recirculation" has the advantage that, through multiple recirculation loops, the gas is continuously heated until it reaches the temperature required for melting. This recirculation process is particularly energy-efficient.

[0091] Furthermore, the K1 and K2 are preferably provided so that the exhaust gas mass flow from the melting chamber 11 to the environment can be controlled, whereby the flap K3 can also be provided here, which can allow parts of post-treated exhaust gas, e.g. post-burned gas, into the recirculation line 13, also to increase efficiency and / or to adjust reducing gas proportions.

[0092] As mentioned, the control lines of these parts are shown interrupted for clarity, but they are connected to the control device 10, as are the schematically drawn sensors for transmitting measured values ​​or the like.

[0093] The control system and melting furnace shown schematically here achieve the aforementioned technical advantages, and it should also be noted that modifications, variations, additions, and combinations of aspects are likewise covered by this disclosure, insofar as they are readily apparent to a person skilled in the art. BORBET GmbH August 2025 220815PC

[0094] Reference symbol list

[0095] I Melting furnace

[0096] 3 Fuel heating system

[0097] 5 electric heating device

[0098] QB Energy input Fuel heating system

[0099] QE Energy input electric heating device

[0100] 7 Melting chamber

[0101] 9 Sensor Melting Chamber

[0102] II Sensor Exhaust pipe

[0103] 12 Exhaust aftertreatment system

[0104] 13 Recirculation line

[0105] V compressor

[0106] E One or more electrical power sources

[0107] B One or more fuel sources

[0108] SG Schmelzgut

[0109] Class 7 control valves

[0110] 10 Control device

[0111] 10a processor

[0112] 10b memory

Claims

BORBET GmbH August 2025 220815PC REQUIREMENTS 1. Control device (10) for operating a melting furnace (1), in particular for melting metals and / or metallic components, wherein the melting furnace (1) has at least one fuel heating device (3) and at least one electric heating device (5) for heating at least one melting chamber (7) of the melting furnace (1); and wherein the control device (10) is configured, - to establish a ratio between the energy input (QB) of the at least one fuel heating device (3) and the energy input (QE) of the at least one electric heating device (5) into the melting chamber (7).

2. Control device according to claim 1, wherein the control device is configured to control the energy input of the at least one fuel heating device (3) and the at least one electric heating device (5) into the melting chamber (7) such that the sum of the energy inputs by fuel heating device (3) and electric heating device (5) corresponds to a preset total energy input target value.

3. Control device according to claim 1 or 2, wherein the control device is configured to adjust the ratio of the energy inputs of the least one fuel heating device (3) and the at least one electric heating device (5) such that the operating costs of the melting furnace (1) are minimized, at least to the extent of the sum of the electricity price and the fuel price.

4. Control device according to at least one of the preceding claims, wherein the control device is configured to adjust the ratio of the energy inputs of the least one fuel heating device (3) and the at least one electric heating device (5) such that a predetermined maximum emission value of the melting furnace (1) is not exceeded or an emission value is minimized, in particular that a predetermined CO2 emission value is not exceeded or a CO2 emission value is minimized. BORBET GmbH August 2025 220815PC 5. Control device according to at least one of the preceding claims, wherein the control device comprises an artificial intelligence (AI) control module having a trained artificial intelligence (AI), and the AI ​​control module is configured to set the ratio of the individual energy inputs of the least one fuel heating device (3) and the at least one electric heating device (5) as a control target of the control device.

6. Control device according to at least one of the preceding claims, wherein the control device comprises a rule-based control module which is configured to set the ratio of the individual energy inputs of the least one fuel heating device (3) and the at least one electric heating device (5) as a control objective of the control device.

7. Control device according to at least one of the preceding claims, wherein the control device controls the energy input into the melting chamber (7) such that the control device controls the fuel supply to the fuel heating device (3) and the current supply to the electric heating device (5).

8. Control device according to at least one of the preceding claims, wherein the control device is configured to control a reduction gas supply to the melting chamber (7), preferably based on measurement results of at least one sensor (9) in the melting chamber (7) for detecting oxidative gas components.

9. Control device according to at least one of the preceding claims, wherein the control device is configured to supply hot gas from afterburned exhaust gas of the melting chamber (7) to at least one fuel heating device (3), and / or to adjust an exhaust gas mass flow from the melting chamber (7) based on the proportion of energy input by at least one fuel heating device (3) to the total energy input. BORBET GmbH August 2025 220815PC 10. Melting furnace (1) with at least one melting chamber (7), several heating devices (3, 5) for heating the melting chamber (7) and a control device according to at least one of the preceding claims, wherein the several heating devices (3, 5) comprise at least one fuel heating device (3) and at least one electric heating device (5) for heating the melting chamber (7) of the melting furnace (1).

12. Melting furnace (1) according to claim 10, wherein at least one fuel heating device (3) is configured as a gas burner, in particular for natural gas, hydrogen, propane or other gas mixtures.

12. Melting furnace (1) according to at least one of claims 10 to 11, wherein the electric heating device (5) is connected to one or more power sources, wherein the power sources include: the power grid and / or directly connected power generators, including PV systems, wind turbines, and / or biogas power generation plants.

13. Melting furnace (1) according to at least one of claims 10 to 12, wherein the electric heating device (5) has heating channels (15) for passing gas or air, in which at least one ceramic tube (17) is provided on the outside with induction coils (19), by means of which high-temperature resistant oxidation-resistant ceramic or metal elements (21) arranged inside the tube, between which the gas to be heated can flow, can be inductively heated.

14. Melting furnace (1) according to at least one of claims 10 to 13, further comprising at least one recirculation line (13) for releasing gas from the melting chamber (7) and recirculating the released gas to the multiple heating devices (3, 5), wherein the recirculation line (13) preferably has a supply line for fresh gas, for example ambient air, nitrogen, reducing gas, or the like, and / or a supply line for afterburned gas.

12. Melting furnace (1) according to at least one of claims 10 to 14, further comprising an exhaust device for releasing gas from the melting chamber (7), preferably comprising an afterburner, the outlet of which is connected to the BORBET GmbH August 2025 220815PC recirculation line (13) may be connected and / or a CO2 sensor (11) for detecting the CO2 content in the exhaust gas, and / or at least one sensor (9) for detecting the gas composition in the melting chamber (7), wherein a signal line is provided between sensors (9, 11) and control device, via which sensor readings are transmitted to the control device.

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