Device and method for heating a slab

Abstract

The invention relates to a heating device (1) and to a method for heating a slab (2) made of a steel material. The heating device (1) has at least a first, a second, and a third heating unit (11, 12, 13) which are arranged one behind the other in a passage direction R, and a transport device (14) having transport portions (14-1, ..., 14-6), the latter for transporting the slab from outside the heating device (1) into one of the heating units (11, 12, 13), between the heating units (11, 12, 13), and from the third heating unit (13) to a forming device (30). In order to make the heating process of a slab to a forming temperature necessary for its deformation more energy-efficient and flexible, the heating unit selected as the first to which the slab (2) is supplied from outside the heating device (1) is the one among the first, second, or third heating units (11, 12, 13) having an input temperature range that includes the actual temperature of the slab to be heated, as determined by the temperature-determining device (4).

Description

[0001] Device and method for heating a slab

[0002] Field of the invention

[0003] The invention relates to a device and a method for heating a slab made of a steel material. Furthermore, the invention also relates to a plant with such a heating device.

[0004] State of the art

[0005] Cold slabs are traditionally heated in various furnaces to the rolling temperature before the first pass. The heating process before the first pass in a rolling stand accounts for approximately 80% of the total energy consumption for producing a hot strip. This energy is currently largely provided by fossil fuels.

[0006] WO 2020 / 115 781 A1 describes a process in which different slab dimensions can be formed into a hot strip in a common rolling mill. A continuous caster is directly connected to the rolling mill line and provides hot slabs from the rolling mill's casting process. Using a diverter and additional furnaces, other slab dimensions can be fed into the line as cold slabs.

[0007] EP 0 610 028 A2 shows a method for producing hot strip using a continuous casting and rolling mill, wherein hot slabs can be temporarily stored in an insulated storage unit. The insulated storage unit is arranged parallel to the preheating furnaces of the rolling mill and can exchange slabs laterally to the direction of movement of the slabs in the rolling mill. WO 2023 / 052 500 A1 discloses a method for producing flat rolled products from thick steel or non-ferrous metal slabs. In the method, various electrical heating devices are used to heat the edges and surfaces of the slabs. In the method, it is possible to operate the heating of the slabs by means of at least one inductive heater in an energy-optimized manner by means of a control system. Fixed locations of origin for the slabs are assigned to individual heating devices. In particular, the application at least implicitly discloses the features of the preamble of claim 1.

[0008] The aforementioned and well-known fixed assignment of the place of origin of the slabs, for example storage or casting plant, to a specific heating facility is disadvantageous, in particular inflexible.

[0009] The invention is based on the object of developing a known heating device and a known method for heating slabs, as well as a known plant, in such a way that the heating of a slab to a forming temperature required for forming is made more energy-efficient and more flexible.

[0010] This object is achieved with regard to the heating device by the subject matter of claim 1.

[0011] The term slab is representative of a pre-product made of steel.

[0012] The term casting plant includes a cross-cutting device which serves to separate an initially endless cast strand into individual slabs, i.e. to separate the individual slabs from the cast strand.

[0013] The term "forming device" refers in particular to a rolling stand, a rolling mill, and / or an edger. The term "forming temperature" refers to the temperature the slab must have when it undergoes a first forming step within the forming device. The third target temperature, to which the slab is heated within the third heating device, must be dimensioned such that this forming temperature of the slab is reached in the forming device; any temperature losses during transport between the outlet of the third heating device and the forming device must be taken into account. For the sake of simplicity, however, these losses are neglected in this description and instead the target temperature of the third heating device is equated with the forming temperature.

[0014] By selecting the heating device to which the slab to be heated is to be fed first from outside the heating device, not only is this one selected heating device, but also all subsequent heating devices and thus an entire heating sequence or heating route for the slab until the required forming temperature is reached, are individually selected and defined. This allows the best heating sequence to be selected for each slab depending on its current temperature; in this respect, the claimed selection is flexible. Furthermore, not every slab always needs to pass through all the heating devices; this is energy-efficient. Passing through one or more of the different heating devices can take place without changing the furnace curves.

[0015] The core of the invention is the definition of an energy-optimized sequence of different heating steps, depending on the actual temperature of the slab.

[0016] According to a first embodiment of the invention, the first heating device is a preheating device assigned to a first inlet temperature range. The first heating device slowly heats the slabs to a maximum of a first target temperature. The first target temperature can correspond to the final temperature of the first inlet temperature range. Slow heating prevents the formation of cracks during the subsequent inductive heating phase. Slow heating is also advantageous compared to holding the slab in the third heating device for a longer period at a temperature close to the forming temperature, as this would result in undesirable structural changes. Finally, preheating also significantly reduces energy consumption in the third heating device, making it more energy-efficient overall.

[0017] In the second heating device, which is operated inductively and has a second input temperature range, the slabs are heated to a second target temperature that is coordinated with the third heating device. Thanks to the easily controllable electrical energy of the slab, which can be provided by renewable energy sources, the second heating step can be precisely adjusted to the input temperature and the specific nature of the material in terms of magnetic properties. Furthermore, the heating steps can be precisely controlled by balancing the core and surface temperatures. This is particularly advantageous when the second furnace is constructed from several inductors arranged in series. This means that heating can be used effectively even when the Curie temperature is exceeded.

[0018] In the third heating device, which is assigned a third inlet temperature range, the slabs are heated to a third target temperature, typically the forming temperature required for forming the slabs, in particular for rolling in the forming device. This heating device is fired with natural or artificial gas, oil, hydrogen, or similar. If a simulation or prediction of the temperature of the slab in the third heating device using a temperature model, or a measurement of this temperature, shows that the required forming temperature has not yet been reached, the slab's residence time in the third heating device is extended until the forming temperature is reached.

[0019] The various heating devices can be used to perform specific heat treatments on the slabs in an energy-optimized manner to specifically create specific microstructures, especially prior to forming. Especially in steel materials, this method can be used to specifically create or suppress precipitation at grain boundaries.

[0020] A cooling device, in particular a cooling device with water, water-air or air as coolant, can preferably be used for the targeted and energy-optimized cooling of a slab made of a special, e.g. micro-alloyed material, before this slab is then later fed back to the first or second heating device.

[0021] A higher-level control, in the form of a pure control or a regulation, controls / regulates the processes in the heating device or the system according to the invention, preferably by means of a process model or a production planning model for carrying out the method according to the invention.

[0022] The latter model, for example, optimizes the production sequence of production orders, in particular the feeding of slabs with their different actual temperatures, using an optimization algorithm and / or self-learning artificial intelligence to minimize the energy consumption of the heating devices in relation to the total energy consumption or the slab-specific energy consumption. The production planning model specifies, for example, a specific time-temperature curve for each individual slab. Finally, the heating device can provide a recuperation system for transferring the waste heat from the third heating device to the first heating device, i.e. from the more energy-intensive heating device with the greatest waste heat to a less energy-intensive heating device. Due to its inductive mode of operation, the second heating device does not require any additional heat supply.

[0023] Furthermore, the above-mentioned object of the invention is achieved by a system according to claim 6 and a method according to claim 7. The advantages of these solutions correspond to the advantages mentioned above with reference to the claimed heating device.

[0024] A particular advantage of the method according to the invention, however, lies in the calculation of a start time for feeding the slab to the selected heating device with the aid of the process model such that the slab is heated to the forming temperature and has reached the forming device by the forming time. This calculation is carried out, for example, with the aid of a product planning, temperature and / or process model of the control system, and is optimized in terms of time and / or energy. Optimized in terms of time means that as little time as possible passes between the start time and reaching a forming time at which the slab enters the forming device at the forming temperature. Energy optimized means that as little energy as possible is consumed during this time, both in terms of the energy consumption of an individual slab and in terms of the overall energy consumption of the plant.Due to its design, the third heating device has the advantage that disruptions in rolling operations can be buffered, so that delays do not directly lead to the unnecessary removal of a slab from the third furnace, which would otherwise result in undesirable cooling effects. Further advantageous embodiments of the heating device, the system, and the method according to the invention are the subject of the dependent claims.

[0025] The description is accompanied by Figure 1, which illustrates the system according to the invention with the heating device according to the invention and the method according to the invention.

[0026] The invention is described in detail below with reference to the figure in the form of exemplary embodiments.

[0027] Fig. 1 shows the plant 100 according to the invention, for example a steelworks. It has a first storage area 21, in particular an open-air storage area without a (heat) insulation hood, in which the slabs are stored, for example, at an actual temperature equal to the ambient temperature or at an actual temperature of, for example, up to 400°C. Alternatively or additionally, the plant 100 can have a second storage area 2T covered by a (heat) insulation hood, for storing slabs with an actual temperature of, for example, up to 900°C. The storage areas can also be slab pits. Furthermore, the plant 100 can have a casting plant 22 for producing slabs 2 with an actual temperature of, for example, >900°C at the outlet of the casting plant.

[0028] Furthermore, the system 100 comprises a heating device 1 according to the invention with a first, second, and third heating device 11, 12, 13. The first and third heating devices 11 are each designed as a heating device operated with a fuel, in particular with natural gas, hydrogen, and / or petroleum. The second heating device 12 is operated inductively, ie, with electrical current.

[0029] In addition to the heating devices, the heating device 1 and thus also the plant 100 has a transport device 14 with transport sections 14-1 to 14-6, e.g. in the form of driven roller tables, which are also designed, among other things, to transport the slabs 2 from outside the heating device 1, ie from one of the stores 21, 21' or from the output of a

[0030] Slab treatment device 23 or the casting plant 22, in the latter case utilizing the casting heat, to a selected heating device of the heating device 1. For this purpose, at least some of the transport sections are suitably controlled by the control system.

[0031] At least some of the transport sections, in particular the intermediate transport sections 14-2, 14-3 between each two of the

[0032] Heating devices may have an insulation hood for forming thermally insulated areas 141 and / or thermally insulated storage locations 142 for the slabs 2.

[0033] Each of the heating devices 11, 12, 13 has its own internal transport devices, e.g. in the form of driven roller conveyors for feeding, passing through and discharging the slabs.

[0034] A temperature determination device 4 of the heating device 1 and thus also of the system 100 serves to determine the current actual temperature of the slab or to predict or recalculate its temperature. The temperature can be determined by measurement, in particular at locations in the system that are easily accessible, e.g., the storage area 21, 2T or a slab treatment device 23, the casting system 22, at the inlets or outlets of the heating devices 11, 12, 13 or the forming device 30, or on the transport sections. Alternatively, the temperature of the slab can also be determined by simulation using a temperature model, which can be assigned to the control system or the temperature determination device, typically in locations that are difficult to access, such as inside the heating devices or inside the forming device.A higher-level control system 3 of the heating device 1 and thus also of the plant 100 is designed to control or regulate the heating devices 11, 12, 13 and the transport device 14 for the slabs 2 for carrying out the method according to the invention, preferably also taking into account the temperatures determined by the temperature determination device.

[0035] The heating device 1 and thus also the system 100 can also be provided with a recuperation system 6 which is connected to the first and the third heating device 11, 13 for transferring the waste heat of the third heating device 11 to the first heating device 13 in order to save energy and costs in this way.

[0036] Finally, the plant 100 also includes a forming device 30, in particular a rolling mill and / or an edger device, connected downstream of the heating device 1 and in particular its third heating device 13, for forming the slabs 2 heated to the forming temperature in the third heating device 13.

[0037] The heating device 1 serves to heat the slab 2 made of a steel material. Its three heating devices 11, 12, 13 are arranged one behind the other in a flow direction R. Its transport device 14 with the transport sections 14-1 ... 14-6 serves not only to transport the slab from outside the heating device 1 to the selected heating device, but also to transport the slab in the flow direction R between the heating devices 11, 12, 13 and to transport the slab from the third heating device 13 to the forming device 30. All of this, as well as the interaction with the temperature determination device 4, is coordinated, in particular controlled or regulated, by the higher-level controller 3. In particular, all transport sections 14-1 ... 6 are suitably controlled, as required, to carry out the (working) steps of the method according to the invention.The first heating device 11 with an associated first input temperature range for the slabs to be heated of, for example, up to 400°C is set up and designed to heat the slab to a first target temperature, for example <450°C or <400°C.

[0038] The second heating device 12 is designed as an inductive heating device with an associated second input temperature range for the slab to be heated of, for example, 400°C to 900°C and is arranged and designed to heat the slab to a second target temperature of, for example, <950°C or <900°C.

[0039] The third, conventional heating device 13 with an associated third input temperature range for the slab to be heated of, for example, > 900°C is set up and designed to heat the slab 2 to a third target temperature, typically a material-specific forming temperature Tu, for example from a range of 1230°C to 1250°C, in particular a rolling temperature.

[0040] The target temperatures preferably correspond to the maximum temperature of the respective input temperature range.

[0041] The three inlet temperature ranges are preferably adjacent to one another. This has the advantage that each slab with an actual temperature up to the level that defines the end of the third inlet temperature range, e.g., the third target temperature, can be clearly assigned to exactly one of the three heating devices through which the slab should pass first.

[0042] The higher-level controller 3 is designed to carry out the method according to the invention. This includes selecting the first, second, or third heating device 11, 12, 13 within whose input temperature range the actual temperature of the slab to be heated, determined by the temperature determination device 4, falls; see the dashed selection area in Fig. 1. The slab to be heated is first fed from outside the heating device 1 to precisely this selected heating device. For this purpose, the transport sections of the transport device are controlled accordingly, as previously described.

[0043] Thus, according to the method according to the invention, a slab with an actual temperature of, for example, <400°C, in particular with the ambient temperature as the actual temperature, is first introduced into the first heating device 11 in the form of a preheating device, before subsequently passing through the second and third heating devices 12, 13. This means that, in a cold feed, all heating devices 11, 12, 13 are passed through in sequence. Slabs with such comparatively low actual temperatures typically come from the (slab) storage area or from the (slab) pit without an insulation hood.

[0044] According to the method according to the invention, a slab with an actual temperature between, for example, 400°C and 900°C is first introduced into the second heating device 12 in the form of an induction heating device before subsequently passing through the third heating device 13. Such slabs are preheated accordingly and can, for example, come from the slab storage area or the slab pit with an insulation hood.

[0045] Finally, a slab with an actual temperature of, for example, > 900°C is first or directly fed into the third heating device 13, where it is further heated to the forming temperature required for subsequent forming in the forming device 30. Slabs with such a high actual temperature typically come directly from a casting plant. The remaining casting heat in the slab 2 is optimally utilized; this saves energy costs for subsequent reheating, which would be necessary if the slab 2 were to cool down in the meantime.

[0046] In this way, slabs - regardless of their origin - can be fed into the forming device at any actual temperature in an energy-efficient manner using the method according to the invention. This procedure is energy-efficient and flexible because not all slabs are treated the same and do not always have to pass through all heating devices. As a result, i.e. the targeted, selective first feeding of the slabs to an individually and specifically selected heating device according to the invention, it is advantageously achieved that energy can be saved in the first heating device, for example, approx. 80%, in the second heating device, for example, approx. 60%, and in the third heating device, for example, approx. 55%. This applies in comparison to a situation where all slabs are always passed through all heating devices.

[0047] To carry out the described selection procedure, the actual temperature of the slab to be heated is determined at the beginning using the temperature determination device 4.

[0048] According to one embodiment, the starting time at which the slab to be heated is fed to the selected heating device can be determined by performing the following steps:

[0049] - Determining a forming time t u to which the slab 2 is to be fed to the forming device 30;

[0050] - Calculating the duration of the individual heating steps with the aid of a process model 31, which is preferably assigned to the higher-level control system 3, depending in particular on the actual temperature of the slab 2 before it enters the selected heating device and the target temperature at the end of each heating step; and

[0051] - Calculating the starting time for feeding the slab 2 to the selected heating device 11, 12, 13 with the aid of the process model so that the slab is heated to the forming temperature Tu at the forming time tu and has reached the forming device 3.

[0052] The calculation of the starting time is based on the forming time t u taking into account the duration of the required heating steps and the duration of the transport times of the slab from outside the heating device 1 into the selected heating device. In each case, the duration of the transport time from the third heating device 13 to the forming device 30 is always taken into account. If necessary, ie, if the material is not fed directly into the third heating device, the duration of the transport times between individual heating devices 11, 12, 13 is also taken into account.

[0053] The process model 31 or a production planning model can optimize the starting time for feeding the slab 2 to the selected heating device 11, 12, 13 by means of an included optimization algorithm or by means of self-learning artificial intelligence in such a way that the amount of energy required to heat the slab 2 to the forming temperature Tu and / or the processing time, e.g. the number of necessary heating steps, is minimized.

[0054] The third heating device 13 can be used as a time buffer in the event of a scheduled and / or unscheduled interruption of one of the heating steps, by temporarily storing the slab therein until the forming device is available for its forming. Alternatively or simultaneously, the third heating device 13 can also be used to equalize the temperature of the slab located therein.

[0055] List of reference symbols

[0056] 1 heating device

[0057] 2 slabs

[0058] 3 (higher-level) control

[0059] 31 Process model

[0060] 4 Temperature determination device

[0061] 6 Recuperation system

[0062] 11 first heating device

[0063] 12 second heating device

[0064] 13 third heating device

[0065] 14 Transport device

[0066] 14-1 ... -6 first to sixth transport section

[0067] 21 warehouses, especially open-air warehouses

[0068] 21 ' bearings, especially with heat insulation hood

[0069] 22 Casting plant

[0070] 23 Slab treatment plant

[0071] 30 forming device

[0072] 31 Process model

[0073] R Flow direction

[0074] Tu forming temperature tu forming time

[0075] REVISED SHEET (RULE 91) ISA / EP

Claims

Patent claims 1. Heating device (1) for heating a slab (2) made of a steel material, comprising at least a first, a second and a third heating device (11, 12, 13) which are arranged one behind the other in a direction of travel (R), a transport device (14) with transport sections (14-1 ... 14-6) for transporting the slab from outside the heating device (1), in particular from a casting plant (22) or from a storage area (21, 21'), into one of the heating devices (11, 12, 13), for transporting the slab between the heating devices (11, 12, 13) in the direction of travel (R) and for transporting the slab from the third heating device (13) to a forming device (30); and a higher-level control (3) for controlling or regulating the heating devices (11, 12, 13) and the transport device (14);characterized in that a temperature determination device (4) is provided for determining the actual temperature of the slab (2) to be heated, at least before the slab (2) is fed to one of the heating devices (11, 12, 13); the first heating device (11) is set up with an associated first input temperature range for the slabs to be heated and is designed to heat the slab to a first target temperature; the second heating device (12) is set up as an inductive heating device with an associated second input temperature range for the slab to be heated and is designed to heat the slab to a second target temperature; and the third heating device (13) is set up with an associated third input temperature range for the slab to be heated and is designed to heat the slab (2) to a third target temperature, in particular a material-specific forming temperature (Tu) for the; Slab; and the higher-level control (3) is designed to select that of the first, second or third heating devices (11, 12, 13) in whose input temperature range the actual temperature of the slab to be heated, determined by the temperature determination device (4), falls, as the heating device to which the slab to be heated is to be fed first from outside the heating device (1), and to control the transport sections of the transport device such that the slab (2) to be heated is fed to the selected heating device.

2. Heating device (1) according to claim 1, characterized in that the first heating device (11) is designed as a heating device operated with a fuel, in particular with natural gas, hydrogen and / or petroleum.

3. Heating device (1) according to claim 1 or 2, characterized in that the third heating device (13) is designed as a heating device operated with a fuel, in particular with natural gas, hydrogen and / or petroleum.

4. Heating device (1) according to one of the preceding claims, characterized in that the at least one of the transport sections of the transport device (14), in particular the intermediate transport sections (14-2, 14-3), have an insulation hood for forming thermally insulated areas (141) and / or thermally insulated storage locations (142) for the slab (2).

5. Heating device (1) according to one of the preceding claims, characterized in that a recuperation system (6) is provided which is connected to the first and the third heating device (11, 13) for transferring the waste heat of the third heating device (11) to the first heating device (13).

6. Plant (100), in particular a steelworks, comprising: at least one storage area (21, 21'), with or without a (heat) insulation hood, for storing slabs (2), for example with an actual temperature at ambient temperature or in a preheated state, alternatively or in addition to the storage area: a casting plant (22) for producing slabs (2), in particular with an actual temperature of >900°C; a heating device (1) with three heating devices (11, 12, 13), a transport device, a temperature determination device and a higher-level control system according to one of the preceding claims, wherein the transport device (14) is also designed to feed the slabs (2) from the storage area (21) or from the outlet of the casting plant (22), in the latter case utilizing the casting heat, to the selected heating device of the heating device (1);wherein the higher-level control system (3) is designed to control or regulate the heating device (1), in particular with the heating devices (11, 12, 13) and the transport device (14), for carrying out the method according to the invention; and a forming device (30) connected downstream of the third heating device (13) of the heating device (1) for forming the slabs heated to the forming temperature (TU) in the third heating device (13); 7. A method for heating a slab (2) made of a steel material with a heating device (1) according to one of the preceding claims, wherein at least the following working steps take place: - Determination of a material-specific forming temperature (T u ), in particular a rolling temperature for the slab (2) provided from outside the heating device; - Determining the actual temperature of the slab (2); - selecting the heating device(s) (1, 2, 3) to which the slab (2) to be heated is to be fed first as the heating device in whose inlet temperature range the actual temperature of the slab to be heated, determined by the temperature determining device (4), falls; - feeding the slab (2) to the selected heating device (11, 12, 13) via a transport section (14-1 14-6) of the transport device and passing through this selected heating device first; - subsequently: transporting the slab (2) through the heating devices possibly following in the direction of passage (R), wherein the slab (2) is heated in the heating devices passed through to its respective target temperature, wherein the heating of the slab (2) in each heating device passed through represents a separate heating step, and wherein the slab is heated in the third heating device (13) passed through in each case to the forming temperature (Tu) as the third target temperature; and - After the slab (2) has run out of the third heating device at the forming temperature: transport the slab (2) to the forming device.

8. Method according to claim 7, characterized by - conducting the waste heat, preferably the exhaust gas, of the third heating device (13) into the first heating device (11) in order to heat the slab (2).

9. Method according to claim 7 or 8, characterized by Setting a forming time (t u ) to which the slab (2) is to be fed to the forming device (30); Calculating the duration of the individual heating steps with the aid of a process model (31), which is preferably assigned to the higher-level control (3), depending in particular on the actual temperature of the slab (2) before it enters the selected heating device and the target temperature at the end of each heating step; and Calculating a starting time for feeding the slab (2) to the selected heating device (11, 12, 13) with the aid of the process model such that the slab is heated to the forming temperature (Tu) at the forming time (tu) and has reached the forming device (3); wherein the calculation of the starting time is based on the forming time (t u) and taking into account the duration of the required heating steps and the duration of the transport times of the slab from outside the heating device (1) into the selected heating device, if necessary the duration of the transport times between individual heating devices and the duration of the transport time from the third heating device (13) to the forming device (30).

10. The method according to claim 9, characterized in that the process model (31) or a production planning model optimizes the starting time for feeding the slab (2) to the selected heating device (11, 12, 13) or its calculation by means of an included optimization algorithm or by means of self-learning artificial intelligence in such a way that the amount of energy required to heat the slab (2) to the forming temperature (Tu) and / or the number of necessary heating steps are minimized.

11. Method according to one of claims 7 to 10, characterized in that the first heating device (11) is supplied with slabs (2) having an actual temperature < 400°C; and the slabs (2) are heated to a maximum temperature of 400°C with the first heating device (11).

12. Method according to one of claims 7 to 11, characterized in that the second heating device (12), preferably an inductive heating device, is supplied with slabs (2) having an actual temperature between >400°C and 900°C; and the slabs (2) are heated to a maximum of 900°C as the target temperature (T z ) are heated with the second heating device (12).

13. Method according to claims 7 to 12, characterized in that slabs (2) with an actual temperature >900°C are fed to the third heating device (13); and the slabs (2) are heated to the forming temperature (T u) of the material of the slab (2) are heated with the third heating device (13).

14. Method according to claim 7 to 13, characterized in that the heated slabs (2) are temporarily stored in a heat-insulated area (141) and / or heat-insulated storage location (142) of the transport device (14) after heating.

15. Method according to one of claims 7 to 14, characterized in that the third heating device (13) is used as a time buffer, for example in the event of a planned and / or unscheduled interruption of one of the heating steps, by temporarily storing the slab located therein until the forming device (30) is available for its forming; and / or that the third heating device (13) is used to equalize the temperature of the slab located therein.

16. Method according to one of claims 7 to 15, characterized in that the slabs (2) are fed from one of the stores (21), an upstream slab treatment device and / or the casting plant (22) to the selected heating device (11, 12, 13).

17. Method according to one of claims 7 to 16, characterized in that the slabs (2) are rolled and / or upset in the forming device (30).

18. Method according to one of claims 7 to 17, characterized in that slabs (2) made of special materials, such as micro-alloyed steels, with actual temperatures of greater than 900°C are first cooled to a temperature of less than 550°C with the aid of a cooling device using, for example, water and / or air.

19. Method according to claim 18, characterized in that these slabs are then subsequently - depending on their actual temperature the cooling, the first or the second heating device.

20. Method according to one of claims 7 to 19, characterized in that the actual temperature of the slab is determined with the aid of the temperature determination device (4), by measurement or by simulation with the aid of a temperature model which can be assigned to the control and / or the temperature determination device (4). 21 .Method according to claim 20, characterized in that the actual temperature of the slab, in particular in one of the stores (21, 21') or at the exit of the slab treatment device or the casting plant (22), as required for selecting the heating device to be passed through first or for calculating the starting time for feeding the slab to the selected heating device, is measured with the aid of the temperature determination device.

22. Method according to one of claims 9 to 20, characterized in that the temperature of one of the slabs at any desired point in time, in particular at the specified forming time (tu), or at any desired location during its passage through the heating device (1), in particular within one of the heating devices, or behind it, can be calculated in advance or tracked with the aid of the temperature model.

23. Method according to one of claims 9 to 22, characterized in that the process model (31) or the production planning model is contained optimization algorithm' or by means of self-learning artificial intelligence, a specific time-temperature curve is specified for at least one of the slabs (2) to be heated.

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