Installation and process for producing a metal strip in continuous mode or in batch mode

Abstract

The present invention is in the field of combined casting and rolling processes, which can be carried out both in a continuous mode and in a batch mode. The object of the present invention is to provide a compact metal-strip producing installation which can be operated both in continuous mode and in a batch mode. The object is firstly achieved by an installation which has a first inductive heating furnace (25) between the last strand guiding roller and the first separating device (3). At least one slab manipulation device (25a) for feeding and discharging cut slabs is downstream of the first separating device (3). A second continuous casting installation (2) with a second separating device (4) for separating a strand into second slabs (42) is parallel to a first casting installation (1). A second inductive heating furnace (28) is upstream of the second separating device (4), and a transport device (18) is downstream of the second separating device (4).

Description

[0001] 202400302

[0002] 1

[0003] Description

[0004] Title of the invention

[0005] Plant and process for producing a metal strip in continuous or batch operation

[0006] field of technology

[0007] The present invention relates to combined casting and rolling processes, which can be operated in both continuous and batch operation.

[0008] On the one hand, the invention relates to a system for producing a metal strip, comprising the following system components

[0009] - a first continuous casting plant, wherein the end of the casting plant is determined by a strand guide roller arranged as the last,

[0010] - one of the first casting plants, a first separating device for separating a strand into first slabs,

[0011] - a rolling mill downstream of the first cutting device, wherein a beginning of the rolling mill is determined by a rolling stand arranged as a first,

[0012] - a shear downstream of the rolling mill

[0013] - a reeling device downstream of the scissors,

[0014] - an automation device that can control the system in such a way that it can be operated in continuous or batch mode.

[0015] On the other hand, the invention relates to a method for producing a metal strip using the system.

[0016] State of the art

[0017] Combined casting and rolling processes are currently replacing the conventional methods of thick slab casting and hot strip milling.

[0018] The most important advantages of combining casting and rolling processes in continuous operation: Minimal energy consumption

[0019] - Reduced or no CO2 emissions

[0020] - Production of ultra-thin tapes

[0021] - Highest consistent quality in continuous operation

[0022] - Lower investment costs 202400302

[0023] 2

[0024] - Lower operating costs

[0025] Since the mass flow through the entire system is essentially constant in continuous operation and no phased acceleration to bridge longer distances is possible, many advantages of continuous operation are linked to the short overall length of the system.

[0026] However, in many cases a single-strand casting and rolling mill is insufficient to completely replace an existing hot strip mill and all its products due to the mass flow limitations of today's casting process.

[0027] The maximum mass flow rate that a continuous casting plant can currently deliver is in the range of 7 to 8 tons per minute. This results in a maximum annual production of approximately 3 million tons per year. High-performance hot rolling mills, on the other hand, have a production volume between 4 and 6 million tons per year (Mt / J), which can easily be double that of a continuous casting plant.

[0028] Therefore, steel producers try to combine two continuous casting plants with one rolling mill to achieve the same capacity, e.g.: 2.5 Mt / J with casting plant 1 + 2.5 Mt / J with casting plant 2 = 5 Mt / J for one rolling mill

[0029] By definition, this means that continuous operation is not possible when producing two casting strands.

[0030] Since many demanding grades (ultra-thin and high-quality) can only be produced in continuous operation, steel manufacturers want a plant that meets both requirements:

[0031] - Continuous line for the production of ultra-thin, high-quality grades

[0032] - High-capacity plant for combining two casting plants with a rolling mill

[0033] A system should meet the following requirements:

[0034] - Flat sheet metal production in the dimension range of:

[0035] Thickness 0.6 to 32 mm, preferably: 0.8 to 25.4 mm

[0036] Width 600 to 2600 mm, preferably 900 to 2134 mm

[0037] - All steel grades with a carbon content of 0.001% to 1%, preferably 0.005% to 0.5%

[0038] - Standard grades requiring high productivity, produced using rapid casting

[0039] - Special grades that require slow solidification, achieved through slow pouring.

[0040] - Productivity: 3 to 8 Mt / year (preferably 4 to 6 Mt / year) 202400302

[0041] 3

[0042] Due to the demand for continuous production, there have recently been developments to also use continuous operation on combined twin-strand slab casting and rolling mills.

[0043] These solutions are currently characterized by large distances between the casting and rolling sections, which are necessary to link the production of the two strands.

[0044] To overcome heat losses during the transport of the slabs from the casting machines to the rolling mill, tunnel kilns with a length of 150 to 250 m are currently being proposed.

[0045] While these furnaces effectively prevent temperature losses, they are very energy-intensive and require a lot of maintenance. Furthermore, the furnace is always in operation in the line with the rolling mill, even during continuous production.

[0046] However, concepts based on twin-strand casting and rolling concepts have emerged that also offer the possibility of continuous production with a single strand.

[0047] These concepts all feature a long tunnel kiln and a heated ferry in front of the rolling mill, which perform the task of buffering and combining in batch operation.

[0048] Batch operation requires two ovens, each up to 250 m long, to be heated continuously, resulting in high energy consumption.

[0049] A plant with a tunnel kiln and heating conveyor must also be bridged during continuous operation. At a casting speed of 4 m / min and a kiln length of 160 m, this takes approximately 40 minutes. This leads not only to high oxidation but also to significant energy losses during this time. Any advantage gained from utilizing the hot core of the strand coming from the casting machine is thus lost after transport through the tunnel kiln. Overall, this setup is not advantageous for continuous operation, as the distance between the casting machine and the rolling mill must be significantly increased.

[0050] Many advantages typically associated with continuous operation, such as low energy consumption, no CO2 emissions, low yield losses, maximum initial frame reductions and thus minimal thicknesses, cannot be fully achieved with this type of plant design.

[0051] Furthermore, the tunnel kiln requires a lot of maintenance, and during maintenance periods neither the continuous casting plant nor the rolling mill can be operated.

[0052] Document EP0872288 A2 shows a casting plant with a shear, a subsequent heating furnace, and a subsequent rolling mill. Slabs produced by a second casting plant can also be fed into the heating furnace. 202400302

[0053] 4

[0054] Document US 2004 / 025320 A1 also discloses a casting plant with a shear and a subsequent heating furnace, as well as a subsequent rolling mill. Furthermore, a second casting plant is also arranged, and the produced slabs can be fed into the heating furnace.

[0055] Document EP 3606681 B1 shows a continuous casting plant which can be operated in both continuous and batch operation; in addition, slabs can be fed to the rolling mill via a heating furnace.

[0056] Summary of the invention

[0057] The object of the present invention is to create a compact system for producing a metal strip, which can be operated both in continuous operation and in batch operation.

[0058] The task is further solved by a system.

[0059] In the system, a first induction heating furnace is arranged between the last strand guide roller and the first cutting device. Downstream of the first cutting device, at least one slab handling device, preferably two slab handling devices, is arranged for feeding and removing cut slabs. The slab handling device can feed or remove the cut slabs transversely to the casting direction and transport them in the casting direction. Parallel to the first casting system, a second continuous casting system with a second cutting device for separating a strand into two slabs is arranged. Upstream of the second cutting device, a second induction heating furnace is arranged, and downstream of the second cutting device, a transport device is arranged.A slab transport device is arranged in such a way that second slabs can be fed to the slab manipulation device and / or first slabs can be removed from the slab manipulation device.

[0060] This arrangement according to the invention makes it possible to avoid CO2 emissions and achieves a compact design.

[0061] The arrangement of the induction heating furnace immediately after the first and second casting systems and before the respective cutting device has proven particularly advantageous. This arrangement makes it possible, for example, to counteract temperature differences between the top and bottom of the first and second slabs, in order to achieve the most constant possible temperature profile across the entire process.

[0062] 5. To ensure the temperature of the entire length of the first slab when it arrives at the rolling mill. These temperature differences arise, for example, because the slab head, due to the existing casting velocity, remains in the area after the separating device for a longer period before it reaches the subsequent rolling mill. The slab is usually accelerated after being cut by the separating device – that is, transported to the subsequent rolling mill at a higher speed than the casting velocity. In the area before the separating device, the speed of a strand is lower, as the transport speed is only increased after the strand has been separated into the first and second slabs. Thus, due to the longer residence time in the induction heating furnace, less power is required for heating, and the furnace can therefore be smaller, since the mass flow is even lower than after the separating device.By pre-calculating the heating power of the induction heating furnace, taking into account the casting speed and the transport speed after cutting, a homogeneous temperature can be achieved along the entire length of the slabs for an optimal subsequent rolling process. However, the exact temperature profile depends on the subsequent rolling process. The slab head area usually requires a higher heating power than the area around the slab foot, as the slab head remains in the area after the cutting device for a longer time. Without additional heating power from the induction heating furnace, the area around the slab head would typically have a temperature that is too low compared to the slab foot due to the longer residence time.Another advantage is that the core of the strand is still hot immediately after casting and before cutting, and the heating of the strand can be limited to the outer layer of the slab to a depth of 30-45 mm from the surface. The penetration depth for inductive heating can be calculated using the following formula:

[0063] 8... Penetration depth f... Operating frequency of inductive heating furnace p... Permeability

[0064] K... electrical conductivity

[0065] By appropriately selecting the operating frequency, the penetration depth can be limited to the required area, ensuring effective heating with minimal power consumption. In the context of this invention, a second casting system is understood to mean that a second casting strand is produced. It is therefore also conceivable that a first casting system could produce a first casting strand and simultaneously produce a second casting strand. The second casting strand would then be the one produced by the second casting system in this invention. 202400302

[0066] 6

[0067] A preferred embodiment provides for a buffer storage tank – with an enclosure featuring thermal insulation, a heat-reflecting surface, and / or a heating element – ​​to be arranged between the slab handling device and the rolling mill. This arrangement allows sufficient time for the heat introduced into the surface of the slabs to penetrate and ensure thorough heating. The enclosure effectively encloses the respective plant section, and the slabs must be fed in through openings, which may also be closable. The enclosure is designed to minimize heat loss. When heat is supplied, the enclosure ensures that it is used as completely as possible to heat the slab and is not lost to the environment. The heat-reflecting surface radiates the heat back onto the slab.

[0068] An advantageous embodiment provides that the transport device, the slab manipulation device and / or the slab transport device has an enclosure with thermal insulation, an enclosure with a heat-reflecting surface and / or an enclosure with a heating device.

[0069] This ensures that the heat loss from the slabs is kept as low as possible for the subsequent rolling process.

[0070] A suitable design provides that the transport device is downstream of at least a buffer storage tank with an enclosure with thermal insulation, an enclosure with a heat-reflecting surface and / or an enclosure with a heating device.

[0071] Another advantageous embodiment provides that at least two buffer storage tanks with an insulated enclosure, an enclosure with a heat-reflecting surface, and / or an enclosure with a heating device are arranged downstream of the transport device, with a slab ferry for transverse transport being arranged between two buffer storage tanks. In the event of an upcoming roll change in the rolling mill or another problem in the plant, the slabs can be kept at the desired temperature or the temperature loss can be minimized.

[0072] Another advantageous embodiment provides that the distance between the end of the first casting plant and the beginning of the rolling mill is less than 150 m, preferably less than 130 m, and particularly preferably less than 110 m. 202400302

[0073] 7

[0074] A preferred embodiment provides that the automation device can control the slab manipulation device in such a way that a first slab cut at the first cutting device can be transported to the rolling mill at a transport speed where the transport speed is greater than a casting speed of the first casting plant.

[0075] A suitable embodiment provides that the first casting plant produces first slabs with a thickness of 100 to 200 mm, preferably 120 to 160 mm.

[0076] An advantageous embodiment provides that the second continuous casting plant produces second slabs with a thickness range that essentially corresponds to that of the first slab, or produces second slabs with a maximum thickness of 250 mm; preferably, these can be reduced in thickness by means of a pre-frame.

[0077] One advantageous embodiment provides that the first induction heating furnace and / or the second induction heating furnace can be controlled by the automation device using a process model and / or regulated by a temperature measurement so that a first slab and / or second slab to be produced has a predetermined temperature profile along its length when it arrives at the rolling mill.

[0078] A process model integrated into the automation system can, for example, calculate the temperature profile of the first and / or second slab during its passage through the system at any time. Such a process model can also determine a desired temperature profile for the first and / or second slab in a rolling mill, leading to the desired result of a produced metal strip. This temperature profile can then be adjusted accordingly. A predefined temperature profile could, for example, show an increased temperature at the slab's base with a monotonically decreasing temperature towards the slab's head, depending on whether or not acceleration occurs in the rolling mill.If no acceleration takes place, the slab foot, for example, can have a significantly higher temperature than if acceleration takes place in the rolling mill, because the slab head is exposed to cooling in the air for a longer period of time without acceleration.

[0079] One advantageous embodiment provides that the first induction heating furnace and / or the second induction heating furnace is controlled by the automation device 202400302

[0080] 8 can be controlled using a process model in such a way that a metal strip to be produced from a first slab and / or second slab has a substantially constant final rolling temperature over its length when leaving the last rolling mill.

[0081] A process model included in the automation system allows the first and / or second heating furnace to be controlled in such a way that a metal strip to be produced has a constant final rolling temperature at the end of the last rolling mill.

[0082] The problem is further solved by a method for producing a metal strip using a previously described system. Depending on a final thickness, a desired CO2 footprint, a predetermined low energy consumption, a predetermined casting speed, and / or a mechanical property of the metal strip to be produced, the system is operated by an automation device in continuous or batch mode.

[0083] The system is operated continuously for grades with a final thickness of less than 1.5 mm. For grades from 1.5 to 2.5 mm, the system is operated continuously or in batch mode, depending on the desired mechanical properties, such as strength.

[0084] If low CO2 emissions and / or low energy consumption are required, the system is operated in continuous operation whenever possible.

[0085] If a quality of metal strip is to be produced which requires slow casting by the casting plant, the plant is operated in batch mode.

[0086] Brief description of the drawings

[0087] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of an exemplary embodiment, which is explained in more detail in conjunction with the drawings. These drawings show:

[0088] Fig. 1-3 shows a schematic representation of a first casting plant with a subsequent rolling mill and a parallel second casting plant with an induction heating furnace.

[0089] Description of embodiments 202400302

[0090] 9

[0091] Figure 1 shows a system with a first induction heating furnace 25 upstream of the first cutting device 3. In this embodiment, a first strand 1a, produced by the first casting plant 1, is heated in the first induction heating furnace 25. Downstream of the first induction heating furnace 25, a first cutting device 3 is arranged, which separates a first slab 40 from the heated strand 1a. A slab handling device 25a for feeding and unloading slabs is arranged downstream of the first cutting device 3. Slabs are transported either to or away from the slab handling device 25a – for example, to a slab storage area 50 – by a slab transport device 16.The slab transport device 16 can, for example, be guided via rails mounted on the ground and a cable, chain, or wheel drive as a slab ferry, or on rails located at a certain height – overhead – as a slab manipulator or crane. Cold slabs 43 stored in the slab storage area 50 can be heated with a third induction heating furnace 27 and then fed to the rolling mill 8 via the slab transport device 16.

[0092] The slab handling device 25a is followed by a buffer storage unit 26, a first intensive heating device 6, and a first descaling device and / or intensive cooling device 7. A rolling mill 8 is arranged downstream. The beginning of the rolling mill 8 is defined by a first rolling stand 8a. The distance L between the end of the casting plant 1 and the beginning of the rolling mill 8 should be as small as possible to minimize potential heat losses from the cast first strand 1a and thus enable continuous operation. The distance L should be less than 150 m, preferably less than 130 m, and particularly preferably less than 110 m. Downstream of the rolling mill 8, a third cutting device 9, a second intensive heating device 10, and a second descaling device and / or an intensive cooling device 11 can be arranged. A further rolling mill 12 can then be arranged.Following this are a cooling device 13, a shear 14, and a reeling device 15 for winding a rolled metal strip. The system includes an automation unit 45, which controls all system components so that the system can be operated either in batch or continuous mode. The automation unit 45 can also include a process model 46 with which the first heating furnace 25 and / or the second heating furnace 28 can be controlled in such a way that a desired temperature profile can be set along the length of the first slab 40 and / or the second slab 42 before the rolling mill 8. Through the automation unit 45 and the process model 46, the first heating furnace 25 and / or the second heating furnace 28 can be controlled so that a metal strip 44 produced at the end of the rolling mill 12 has a constant final rolling temperature.A desired temperature profile could be, for example, that at the base of the slab 40b a 202400302.

[0093] The temperature is 10 times higher than at the slab head 40a, and the temperature from slab foot 40b to slab head 40a decreases monotonically. Such process models are known to those skilled in the art from the prior art, for example in EP2431104A1.

[0094] In Fig. 2, compared to Fig. 1, another slab manipulation device 25a is arranged between the slab manipulation device 25a and a buffer storage tank 26.

[0095] In Fig. 3, a pre-frame 20 is provided upstream of the second induction heating furnace 28 to reduce the thickness of the second strand 2a. The transport device 18 is provided with thermal insulation 18a, followed by buffer storage tanks 26 and a slab ferry 19. The slab ferry 19 is then connected to further buffer storage tanks 26. After the buffer storage tanks 26, the slabs are fed to the slab handling devices 25a by means of the slab transport device 16.

[0096] Although the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived by the person skilled in the art without leaving the scope of protection of the invention.

[0097] 202400302

[0098] Reference symbol list

[0099] 1 first casting system

[0100] 1a first strand

[0101] 2 second watering system

[0102] 2a second strand

[0103] 3 first separating device

[0104] 4 second separating device

[0105] 6 Intensive heating device

[0106] 7 Descaling device and / or intensive cooling device

[0107] 8 Rolling mill

[0108] 8a first rolling mill

[0109] 9 third separating device

[0110] 10 second intensive heating device

[0111] 11 Descaling device and / or an intensive cooling device

[0112] 12 more rolling mills

[0113] 13 Cooling device

[0114] 14 Scissors

[0115] 15 Reel device

[0116] 16 Slab transport device

[0117] 18 T transport device

[0118] 18a Thermal insulation

[0119] 19 Brammen ferry

[0120] 20 Scaffolding

[0121] 25 first induction heating oven

[0122] 25a Slab manipulation device

[0123] 26 buffer storage tanks

[0124] 27 third inductive heating oven

[0125] 28 second induction heating oven

[0126] 30 strand guide segment

[0127] 31 Strand guide roller

[0128] 40 first slab

[0129] 40a Brammenkopf

[0130] 40b Slab foot

[0131] 41 slabs

[0132] 42 second slab

[0133] 43 Cold slabs

[0134] 44 Metal band 202400302

[0135] 12

[0136] 45 Automation equipment

[0137] 46 Process model

[0138] 50 slab bearings

[0139] G Casting direction

[0140] L distance

Claims

1. 202400302 13 Claims 1. Plant for the production of a metal strip, comprising the following plant components - a first continuous casting plant (1), wherein the end of the casting plant (1) is defined by a strand guide roller (31) arranged as the last, - a first separating device (3) downstream of the first casting plant (1) for separating a first strand (1a) into first slabs (40), - a rolling mill (8) downstream of the first cutting device (3), wherein a beginning of the rolling mill is defined by a rolling stand (8a) arranged as the first, - one of the roller mill's (8) shears (14) - a reeling device (15) downstream of the scissors (14), - an automation device (45) which can control the system in such a way that it can be operated in continuous or batch operation, - Following the first cutting device (3) at least one slab manipulation device (25a), preferably two slab manipulation devices (25a), is arranged for feeding and removing cut slabs, wherein the slab manipulation device (25a) can feed or remove the cut slabs transversely to the casting direction (G) and can transport them in the casting direction, wherein -parallel to the first casting plant (1) a second continuous casting plant (2) with a second separating device (4) for separating a cast second strand (2a) into second slabs (40) is arranged, wherein a transport device (18) is arranged after the second separating device (4), - a slab transport device (16) is arranged such that second slabs (42) can be fed to the slab manipulation device (25a) and / or first slabs (40) can be removed from the slab manipulation device (25a), characterized in that a first inductive heating furnace (25) is arranged between the last strand guide roller (31) and the first cutting device (3) and wherein a second inductive heating furnace (28) is arranged in front of the second cutting device (4), 2. Plant for producing a metal strip according to claim 1, characterized in that between slab manipulation device (25a) and the 202400302 14 A buffer storage tank (26) is arranged in the rolling mill, which has an enclosure with thermal insulation (18a), an enclosure with a heat-reflecting surface and / or an enclosure with a heating device.

3. Plant for producing a metal strip according to one of claims 1 or 2, characterized in that the transport device (18), the slab manipulation device (25a) and / or the slab transport device (16) have an enclosure with thermal insulation (18a), an enclosure with a heat-reflecting surface and / or an enclosure with a heating device.

4. Plant for producing a metal strip according to one of claims 1 - 3, characterized in that at least one buffer storage unit (26) with an enclosure with thermal insulation, an enclosure with a heat-reflecting surface and / or an enclosure with a heating device is arranged downstream of the transport device (18).

5. Plant for producing a metal strip according to one of claims 1 - 4, characterized in that at least two buffer storage tanks (26) with an enclosure with thermal insulation, an enclosure with a heat-reflecting surface and / or an enclosure with a heating device are arranged downstream of the transport device (18), wherein a slab ferry for transverse transport is arranged between two buffer storage tanks.

6. Plant for producing a metal strip according to one of claims 1 - 5, characterized in that the distance (L) between the end of the first casting plant (1) and the beginning of the rolling mill (8) is less than 150m, preferably less than 130m, particularly preferably less than 110m.

7. Plant for producing a metal strip according to one of claims 1 - 6, characterized in that the automation device (45) can control the slab manipulation device (25a) in such a way that a first slab (40) cut at the first cutting device (3) can be transported to the rolling mill (8) at a transport speed, wherein the transport speed is greater than a casting speed of the first casting plant (1). 202400302 15 8. Plant for producing a metal strip according to claims 1-7, characterized in that the first casting plant (1) can produce first slabs (40) with a thickness of 100 to 200 mm, preferably 120 to 160 mm.

9. Plant for producing a metal strip according to one of claims 1 - 8, characterized in that the second continuous casting plant (2) can produce second slabs with a thickness range which essentially corresponds to that of the first slab (40) or second slabs (42) with a maximum thickness of 250mm, preferably a pre-frame (20) is arranged which can reduce the thickness of second slabs (42).

10. Plant for producing a metal strip according to one of claims 1 - 9, characterized in that the first inductive heating furnace (25) and / or the second inductive heating furnace (28) can be controlled by the automation device (45) using a process model (46) and / or regulated by a temperature measurement so that a first slab and / or second slab (42) to be produced has a predetermined temperature profile over its length when it arrives at the rolling mill.

11. Plant for producing a metal strip according to one of claims 1 - 9, characterized in that the first inductive heating furnace (25) and / or the second inductive heating furnace (28) can be controlled by the automation device (45) using a process model (46) in such a way that a metal strip (46) to be produced from a first slab (40) and / or second slab (42) has a substantially constant final rolling temperature over its length when leaving the last rolling mill (8, 12).

12. Method for producing a metal strip with a system according to one of claims 1-11, characterized in that the system can be operated in continuous or batch operation depending on the thickness, CO2 footprint, casting speed and / or mechanical strength of the metal strip to be produced, using an automation device (45).

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