Virtual level sensor for mold of continuous casting machine

Abstract

The invention relates to a method for determining a fill level (h1) of a metal melt in a mould (4) of a continuous casting machine by means of a virtual fill level sensor, the metal melt in the mould forming a casting level (5) having the fill level (h1), and a virtual fill level sensor suitable therefor. The aim of the invention is to find a method for determining the fill level in a mold (4) of a continuous casting machine, such that the start and end of casting can be carried out in a fully automated manner without using radiometric sensors. The technical purpose is achieved by the method according to claim 1.

Description

Technical Field

[0001] The invention relates to the technical field of continuous casting. In a continuous casting machine, a metal melt, for example consisting of steel or an aluminum alloy, is continuously or semi-continuously cast into a strand. The metal melt is cast into a mold, in which the mold, which is usually cooled, forms a strand with a thin strand shell, wherein the strand is subsequently released from the mold, for example pulled out. The strand is supported, guided and further cooled in a strand guide downstream of the mold.

[0002] In order to achieve high product quality of the continuously cast strand, an attempt is made to keep the casting liquid level or material level of the metal melt in the mold as constant as possible during continuous casting. It is known that casting liquid level fluctuations lead to expansion of the strand, and severe expansion can lead to strand fracture.

[0003] In particular, the invention relates to a method for determining a filling level of a metal melt, preferably consisting of steel or an aluminum alloy, in a mold of a continuous casting machine by means of a virtual filling level sensor, wherein the metal melt in the mold forms a casting liquid level with a filling level. Background Art

[0004] In order to be able to keep the casting liquid level as constant as possible during continuous casting, it is known in the prior art that the position of the casting liquid level or the fill level of the molten metal in the mold is measured with the aid of a fill level sensor and, for example, the inflow to the molten metal is regulated so that the fill level remains as constant as possible during continuous casting.

[0005] Since the material level is kept constant at approximately ±0.5 mm during continuous casting, it is sufficient to measure the material level during continuous casting by means of a physical sensor, such as an electromagnetic sensor. The signal of this sensor is used to regulate the casting liquid level during the continuous operation of the continuous casting machine. Since the sensor measures the material level accurately at approximately 0.1 mm with high dynamics, the measuring range of the sensor is relatively small, for example a measuring range of 200 mm.

[0006] In a continuous casting machine, the behavior at the so-called start of casting, i.e. at the beginning of casting, and at the so-called end of casting, i.e. at the end of the continuous casting process, is completely different. The phenomenon related to this is explained according to the start of casting: it is known that before the start of casting, a so-called cold casting strand is introduced into the mold, which locks the mold in a fluid-tight manner on the output side. At the beginning of casting, the metal melt is poured into the mold, so that the casting liquid level rises depending on the amount of metal melt input. After the casting liquid level reaches a height of, for example, 400 mm, the cold casting strand begins to be removed from the mold. The casting liquid level is thus lowered, which can be avoided by pouring the metal melt into the mold at the same time. After the start of removal, the casting liquid level typically still rises a little. Because the sensor used to adjust the casting liquid level during continuous continuous casting is highly accurate and highly dynamic, it has a relatively small measuring range, so for certain continuous casting machines, it is not enough to use a sensor at the beginning of casting, for example, for fully automatic adjustment of the casting start.

[0007] In order to solve this problem, two implementation methods are known in the prior art:

[0008] 1) The start and end of casting of the continuous casting machine is carried out manually: This is problematic in that the operator must be on the casting platform or at least near the casting platform in order to be able to properly control the start and end of casting. This is often not desirable or permitted. Furthermore, an experienced operator is required to manually start the casting, which is not always guaranteed.

[0009] 2) In addition to the sensor for adjusting the casting liquid level during continuous casting, an additional physical sensor is used, which has a larger measuring range and can therefore also reflect changes in the casting liquid level during the beginning and end of casting. According to the prior art, this additional sensor usually uses a radiometric radiation source (radiometric level measurement, see e.g. https: / / www.berthold.com / en / processcontrol / knowledge-base / radiometric-mea assurance ). The disadvantages are that the radioactive radiation sources are expensive, additional installation and calibration are required, and the import and export of the sensors often presents problems, for example at customs.

[0010] It is not known from the prior art how the casting level can be measured in a continuous casting machine so that the start and end of casting can be carried out fully automatically and without the use of radioactive measuring sensors. Preferably, no additional physical sensor for determining the filling level of the continuous casting machine is required for the fully automatic control of the start or end of casting. Summary of the invention

[0011] The object of the invention is to find a method for determining the filling level in a mold of a continuous casting machine, which allows the start and end of casting to be carried out fully automatically and without the use of additional filling level sensors, such as radioactive measuring sensors. In addition, the entire filling level measurement should be more suitable than similar solutions with radioactive measuring sensors and the outlay for installation and calibration should be lower.

[0012] On the one hand, this object is achieved by a method according to claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0013] Specifically, the solution is achieved by a method for determining the filling level of a metal melt, preferably consisting of steel or an aluminum alloy, in a mold of a continuous casting machine by means of a virtual filling level sensor, wherein the metal melt in the mold forms a casting liquid level with a filling level, the method comprising the following method steps:

[0014] -Estimation of the volume flow rate Q of the metal melt flowing into the mold through the first state observer 输入 , considering

[0015] an opening of a valve for setting the flow rate of the molten metal from the casting vessel, for example a casting distributor, into the casting tube, the valve being preferably a barrier or a slide, wherein the opening of the valve is determined in real time during the continuous casting,

[0016] --valve geometry, and

[0017] - the geometry of the casting tube,

[0018] - Estimate the volume flow rate Q of the metal melt flowing out of the mold through the second state observer 输出 , considering

[0019] --The geometry of the mold,

[0020] a plurality of, preferably at least three, temperature values, wherein a plurality of temperature sensors determine the temperature value in the mold in real time during the continuous casting, wherein the plurality of temperature values ​​are assigned to different filling level heights, and

[0021] - Casting speed v of the at least partially solidified strand, preferably with a plate or slab cross-section C , wherein the strand is at least temporarily released from the mold during continuous casting and the casting speed v is determined in real time C ,

[0022] - According to the inflow volume flow Q 输入 and the outflow volume flow Q 输入 Calculate the material level h1 accurately, especially through the condition and

[0023] According to the present invention, the material level h1 of the metal melt in the mold of the continuous casting machine is determined by the following steps:

[0024] The first state observer estimates the volume flow rate Q of the molten metal flowing into the mold 输入 , considering

[0025] - opening of the valve for setting the flow rate of the molten metal from the casting vessel into the casting tube 阀 The valve is preferably a stopper or a slider, wherein the opening s of the valve is determined in real time during continuous casting. 阀 ,

[0026] -Valve geometry A 阀 ,and

[0027] - Geometry of the casting tube A SEN .

[0028] The first state observer operates time-continuously or preferably time-discretely and "observes" the volume flow Q into the mold 输入 Of course, it is possible for the state observer to use other input variables to determine the volume flow Q 输入 .

[0029] The second state observer estimates the volume flow rate Q of the metal melt flowing out of the mold 输出 The conditions considered are

[0030] -Mold geometry A 横截面 ,

[0031] a plurality of, preferably at least three, temperature values, wherein a plurality of temperature sensors determine the temperature value in the mold in real time during the continuous casting, wherein the plurality of temperature values ​​are assigned to different filling level heights, and

[0032] - Casting speed v of the ingot C , where the casting speed v is determined in real time during continuous casting C .

[0033] The second state observer can also operate in a time-continuous manner or preferably in a time-discrete manner. The second state observer "observes" the volume flow Q out of the mold. 输出 Of course, it is also possible here for the state observer to use other input variables to determine the volume flow Q 输出 .

[0034] In determining Q 输入 and Q 输出 Afterwards, the virtual level sensor depends on the inflowing volume flow Q 输入 and the outflow volume flow Q 输入For example, the material level h1 is calculated using the following equation:

[0035]

[0036]

[0037] Of course, it is also possible that the observer does not determine the inflow and outflow volume flow Q 输入 , Q 输出 , but the mass flow rate m 输入 =ρ·Q 输入 and the outflow mass flow rate m 输出 =ρ·Q 输出 .

[0038] In particular, in the case of so-called funnel molds, it is possible for the cross section A of the mold to be 横截面 The material level height h1 is not constant, but A 横截面 Depends on material level h1 or A 横截面 It is a function of the material level height, that is, A 横截面 =f(h1).

[0039] In general, the first and second state observers are universal observers, i.e. observers known from the literature, such as the Romberg observer or the Kalman filter. In an advantageous embodiment, the first and / or the second state observer is an incomplete state observer. An incomplete state observer can be a simplified observer, wherein all process variables that can be measured here are derived from the measured values. Another possibility of an incomplete state observer can be a normal observer without measured values, but the model must be accurate enough to be able to calculate the process variables accurately enough without these measured values.

[0040] The geometry of the valve can be, for example, the diameter or area of ​​the opening on the so-called bottom of the casting container. The geometry of the casting tube can be, for example, the inner diameter of the casting tube or the cross-sectional area through which the flow passes. The geometry of the mold can be described, for example, by the cross-sectional area of ​​the mold cavity.

[0041] In order to increase the accuracy of the first state observer, it is advantageous to also include the mass m of the casting container or the casting distributor 分配器 The filling level in the casting container can be determined in a simple manner from the mass of the casting container, possibly in combination with its geometry, wherein a higher filling level is associated with a higher inflowing volume flow Q. 输入 .

[0042] It is also advantageous if a plurality of temperature values ​​are assigned to the first plate, preferably the narrow side plate, of the mold. This allows a rise in the casting liquid level or the filling level to be reliably detected during the start or end of casting. It is also advantageous if a plurality of temperature sensors are arranged at the filling level so that possible measurement errors can be corrected.

[0043] To increase the accuracy, it is advantageous if the second state observer uses, in addition to the temperature values ​​of the first plate of the mold, a plurality of temperature values ​​of the second plate of the mold, wherein the second plate is preferably arranged opposite the first plate in the width or thickness direction. This measure also makes it possible to detect inaccuracies of the sensor or so-called outliers, which increases the accuracy of the virtual sensor.

[0044] In order to be able to measure multiple temperature values, for example, along a straight or curved line, it is advantageous to use an optical fiber temperature sensor. However, the invention is not limited to optical fiber temperature sensors, but any temperature sensor can be used, for example also so-called K-type thermocouples.

[0045] Since the accuracy and dynamic behavior of virtual level sensors are always worse than those of physical level sensors, it is advantageous but not mandatory that the mold has, in addition to a virtual level sensor for observing the level height h1 in a first measuring range, a physical level sensor for measuring the level height h2 of the fluid metal in a second measuring range, wherein the second measuring range is smaller than the first range, in particular the first measuring range is at least twice, preferably four times, larger than the second measuring range.

[0046] By means of this embodiment, during the continuous operation of the continuous casting machine, the casting liquid level is regulated using a physical (e.g. electromagnetic) level sensor. The physical level sensor measures the level height of the liquid metal in the mold relatively accurately in the second measuring range. In contrast, the virtual level sensor measures the level height of the liquid metal in the mold in the first measuring range, wherein, for example, the first measuring range is at least twice, preferably four times, larger than the second measuring range.

[0047] Because the physical level sensor only accurately measures the material level height of the fluid metal in the second measuring range, - if the material level height of the molten metal in the mold is within the second measuring range - the signal of the physical level sensor is used as the material level height, otherwise, that is, when the material level height of the molten metal in the mold is outside the second measuring range, the signal of the virtual level sensor is used as the material level height.

[0048] On the other hand, the object according to the invention is also achieved by a virtual filling level sensor according to claim 10. Advantageous embodiments are the subject matter of the dependent claims.

[0049] Specifically, the solution is implemented by a virtual filling level sensor for determining a filling level h1 of a metal melt, preferably consisting of steel or an aluminum alloy, in a mold of a continuous casting machine, wherein the metal melt in the mold forms a casting liquid surface with a filling level h1, with:

[0050] - Used to observe the volume flow Q into the mold 输入 The first state observer is connected in a signal-transmitting manner to a position sensor of a valve for setting the flow rate of the molten metal from the casting container into the casting pipe, the valve being preferably a barrier or a slide, and the position sensor being able to determine the opening s of the valve in real time during continuous casting. 阀 ,

[0051] - Used to observe the volume flow Q out of the mold 输出 The second state observer is connected to the

[0052] a plurality of, preferably at least three, temperature sensors, wherein the temperature sensors are able to determine temperature values ​​(T1 . . . T3) assigned to different filling level heights in real time during continuous casting, and

[0053] --Casting speed sensor, wherein the casting speed sensor can determine the casting speed v of the billet in real time C ,

[0054] - for the volume flow Q according to the inflow 输入 and the outflow volume flow Q 输入 A calculation unit for accurately calculating the material level height h1.

[0055] Preferably, a level measurement system is used, which has a virtual level sensor for determining a level height h1 of the metal melt in a first measuring range according to claim 10, and a physical level sensor for measuring a level height h2 of the metal melt in a second measuring range, wherein the second measuring range is smaller than the first measuring range, in particular the first measuring range is at least twice, preferably four times, larger than the second measuring range.

[0056] Furthermore, it is advantageous to use a multiplexer for converting the signals for the fill level from the virtual and physical fill level sensors, wherein the multiplexer uses

[0057] - the material level h1 of the molten metal from the virtual material level sensor, and

[0058] - The material level h2 of the molten metal from the physical material level sensor is used as the output variable and input variable of the multiplexer,

[0059] - if the filling level h1 of the virtual filling level sensor is within the second measuring range, the multiplexer uses the filling level h2 of the metal melt from the physical filling level sensor,

[0060] If the filling level height h1 of the virtual filling level sensor is outside the second measuring range, the multiplexer uses the filling level height h1 of the metal melt from the virtual filling level sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The above-mentioned characteristics, features and advantages of the present invention and the manner and method of implementation are clearly and understandably explained in conjunction with the following detailed description of the embodiments in connection with the accompanying drawings. It is shown here:

[0062] Figure 1 is a first overview diagram,

[0063] Figure 2 It is a schematic diagram of the flow lines of the molten metal from the casting liquid distributor through the valve into the casting tube and from the inside of the casting tube through the openings (ports) into the mold cavity of the mold,

[0064] Figure 3 is a diagrammatic representation of the measuring points in the mold and the fill level of the molten metal determined at the start of casting in a continuous casting machine,

[0065] Figure 4 is a second overview diagram with physical and virtual level sensors. DETAILED DESCRIPTION

[0066] Figure 1 An overview schematic diagram for explaining the present invention is shown. During continuous casting, a metal melt, for example consisting of steel or an aluminum alloy, is filled into a casting container 1, here a casting distributor 1a. A casting liquid level indicated by a triangle is formed in the casting distributor 1. The metal melt flows from the casting distributor 1a into the casting tube 3 (submerged entry nozzle, abbreviated SEN). The flow of the metal melt into the casting tube 3 is arranged through a valve 2, here a plug. For this purpose, the plug can be raised or lowered from the bottom of the casting distributor 1a by an embossing drive, not shown here, so that the plug has a distance S from the bottom of the casting distributor 1a. 阀 The bottom of the casting liquid distributor 1a has a diameter d 阀of openings, which are closed by plugs before the start of casting. After the molten metal enters the casting tube 3 and flows through the casting tube 3, the molten metal flows out through the typical multiple openings (English ports) in the lower area of ​​the casting tube 3 and forms a casting liquid level 5 in the mold 4. Whether the opening of the casting tube is arranged below or above the casting liquid level 5 as shown is not important for the present invention. Before the start of casting in the continuous casting machine, the valve 2 is closed so that the molten metal cannot flow into the mold 4. The lower side of the mold 4 is locked by a so-called cold casting billet, so that the mold cavity of the mold is sealed in the direction of the casting liquid. At the beginning of casting, the valve 2 is first opened a little, so that the molten metal can flow from the casting liquid distributor 1a through the casting tube 3 into the mold cavity of the mold 4. At the beginning, the cold casting billet remains stationary in the mold, so that the volume flow Q flowing into the mold 输入 The casting liquid level 5 in the mold 4 reaches a certain height, and the cold casting billet is removed from the mold, so that the hot casting billet (hereinafter referred to as the casting billet) after the cold casting billet is also removed from the mold 4. At the beginning of casting, the hot casting billet is connected to the cold casting billet so that the casting speed of the casting billet corresponds to the removal speed of the cold casting billet. The removal of the casting billet is carried out at the casting speed v C The start of casting is controlled by a virtual level sensor, which determines the level h1 of the molten metal in the mold 4 in an expanded measuring range 7.

[0067] Set the opening of valve 2 to 阀 and geometry and geometry A of the casting tube 3 SEN is provided to the first state observer BEO1. For this purpose, the valve opening s is determined discretely in time, for example with a sampling time of 50 ms. 阀 and is provided to a first state observer BEO1. The observer contains a dynamic model of the metal melt flowing from the casting distributor 1a through the valve 2, from the valve into the casting tube 3, and out of the casting tube 3 into the mold cavity of the mold 4. The structure of the first observer, which can be configured as a so-called Romberg observer or a so-called Kalman filter, is known to the person skilled in the art, so that it is not necessary to study its details. The first state observer BEO1 determines the volume flow Q flowing into the mold 4 输入 .

[0068] Furthermore, according to the present invention, there is a second state observer BEO2, which is based on the temperature values ​​T1, T2, T3 of a plurality of temperature sensors in the mold 4, the casting speed v C and the geometry A used for the mold 横截面 The volume flow Q flowing out of the mold 4 is determined by the parameters 输出 On the other hand, preferably, the temperature values ​​T1, T2, T3 and the casting speed v C It is determined in a time-discrete manner, for example with a sampling time of 50 ms, and is made available to the second state observer BEO2.

[0069] From the inflow volume flow Q 输入 , outflow volume flow Q 输出 and the geometry of the die A 横截面 The time derivative of the material level is calculated by from The material level height h1 is calculated from the integral of

[0070] For example, equations are given which can be introduced into the dynamic model for the first state observer BEO1. Figure 2 A flow line with five points 1 ... 5 is shown. Point 1 is located on the casting surface of the metal melt in the casting distributor 1a. Point 2 is located just before the flow through the valve 2. Point 3 is located after the flow through the valve 2. Point 4 is located just before the flow through the central area of ​​the casting tube 3 and before the so-called opening, and point 5 is located after the flow through the opening of the casting tube 3.

[0071] The pressure p2 at point 2 is Including A 阀 =d 阀 *s 阀 , where p1 is the pressure at point 1 (mostly assuming p1 = 0), ρ Fe is the density of the metal melt, Δh1 is the height difference between the first and second points 1, 2, and Q is the flow rate. The pressure p3 at point 3 is p3 = p2 - R 阀 Q, where R 阀 is the (linearized) hydraulic fluid resistance of valve 2. The pressure p4 at point 4 is Where Δh2 is the height difference between the third and fourth points 3, 4, and L SEN is the hydraulic inductance of the casting tube 3. The pressure p5 at point 5 is p5 = p4 - R 开口 Q, where R 开口 is the (linearized) hydraulic fluid resistance of the openings (ports) of the casting tube 3.

[0072] Figure 3The left side shows a plurality of measuring points 10 of the wide side plate 8 and the narrow side plate 9 of the mold. For example, the measuring points 10 of the wide side plate can be determined by three optical fiber temperature sensors each having 8 measuring points, the measuring points being located in three horizontal holes. It is also possible to use eight optical fiber temperature sensors each having 3 measuring points. The five measuring points 10 of the narrow side plate can be determined, for example, by an optical fiber temperature sensor having 5 measuring points. The temperature values ​​at the measuring points 10 shown can be determined optionally using optical fibers or using conventional temperature sensors, such as K-type thermocouples. The second wide side plate, not shown, is implemented identically to the wide side plate 8 shown; similarly, the second narrow side plate, not shown, is implemented identically to the narrow side plate 9 shown. All the measuring points 10 shown are used for Figure 1 The input variables of the second observer BEO2 are shown, and the associated measurement signals are sampled in real time with a sampling time of 0.5 or 1 s. The measuring ranges 7 and 6 of the virtual and physical fill level sensors are also shown. As mentioned at the beginning, at the start of casting, the mold is closed on the outlet side by the cold strand and then a valve, such as a stopcock, is opened between the casting container or the casting distributor and the casting tube. Figure 3 The lower left shows the valve opening svalve with respect to time. The casting liquid level rises slowly by opening the valve - see the determined material level height h1 of the virtual material level sensor. In addition, it should be recognized that the physical material level sensor sends an incorrect material level h2 because the casting liquid level is outside the measurement range. Only after the material level of the metal melt is within the measurement range 6 of the physical material level sensor, the physical material level sensor gives the correct material level height. The casting speed vC rises from 0 to about 1.4m / min in less than about 30s after the start. Subsequently, the casting speed continues to rise slowly and continuously. In the wide side plate 8, 8 measuring points 10 of the temperature sensor are arranged on 4 planes respectively. In the narrow side plate 9, 1 measuring point 10 of the temperature sensor is arranged on 5 planes respectively. Of course, it is possible to arrange more or fewer planes and / or more or fewer measuring points per plane. It can be well recognized on the right side of the figure that the material level height h1 of the virtual sensor determined according to the present invention rises slowly and continuously from a time point of about 8s. It can also be seen that the fill level derived solely from the thermocouples (shown at the bottom) increases suddenly in contrast thereto.

[0073] Figure 4 A second schematic diagram with virtual and physical level sensors 11 is shown. The virtual level sensor 11 is Figure 1 Runs as described. Figure 1 The difference is that the mold 4 is implemented as a funnel mold, wherein the cross-sectional area A of the mold cavity of the mold 横截面is not constant, but varies according to the height h. Additionally, a physical level sensor 11 is marked in the figure, which measures the level height h2 in the range above the mold 4. Not only the level height h1 of the virtual level sensor, but also the level height h2 of the physical level sensor are provided to the multiplexer MUX, which depends on whether the level height h1 of the virtual level sensor is within the measuring range of the physical level sensor. Specifically, if the level height h1 of the virtual level sensor is within the measuring range of the physical level sensor, the output variable h of the multiplexer corresponds to the level height h2 of the physical level sensor. Otherwise, if the level height h1 of the virtual level sensor is outside the measuring range of the physical level sensor, the output variable h of the multiplexer corresponds to the level height h1 of the virtual level sensor. The corresponding output variable of the multiplexer is provided to the so-called 2-level controller L2, which is used to adjust the start of casting and the end of casting where possible. Of course, it is also possible that the multiplexer MUX does not exist as a discrete module, but is executed as a software module in the regulator, and the technical effect is the same.

[0074] Although the present invention has been illustrated and described in detail by means of preferred embodiments, the present invention is not limited to the disclosed examples and other variants can be derived by a person skilled in the art without departing from the scope of protection of the present invention.

[0075] Reference numerals list

[0076] 1 Casting container

[0077] 1a Casting liquid distributor

[0078] 2 valves

[0079] 3 Casting tube

[0080] 4. Mould

[0081] 5 Casting liquid level in the mold

[0082] 6 Measurement range of physical level sensor

[0083] 7 Measuring range of virtual level sensor

[0084] 8 wide side panels

[0085] 9 narrow side panels

[0086] 10 Measuring points of temperature sensor

[0087] 11 Physical level sensor

[0088] A 横截面 Mold geometry

[0089] ASEN Casting tube geometry

[0090] BEO1, BEO2 First and second state observers

[0091] d 阀 Valve geometry

[0092] h1 Material level height of virtual material level sensor

[0093] The time derivative of the material level height of the virtual material level sensor

[0094] h2 Material level height of the physical material level sensor

[0095] L Hydraulic inductor

[0096] L2 Level 2 Controller

[0097] MUX Multiplexer

[0098] Q 输入 Inflow volume flow

[0099] Q 输出 Outflow volume flow

[0100] R hydraulic fluid resistance

[0101] s 阀 Valve opening

[0102] T1...T N Temperature value

[0103] v C Casting speed of the ingot.

Claims

1. A method for determining a fill level h1 of a metal melt, preferably consisting of steel or an aluminum alloy, in a mold (4) of a continuous casting machine by means of a virtual fill level sensor, wherein: The metal melt in the mold (4) forms a casting liquid surface (5) having the material level height h1, and the method comprises the following method steps: - Estimating the volume flow rate Q of the metal melt flowing into the mold (4) by a first state observer (BEO1) 输入 , considering - opening s of a valve (2) for setting the flow rate of the molten metal from the casting vessel (1, 1a) into the casting tube (3) 阀 The valve is preferably a barrier or a slider, wherein the opening s of the valve (2) is determined in real time during continuous casting. 阀 , --The geometric shape of the valve (2) 阀 ,and --Geometric shape A of the casting tube (3) SEN , - Estimating the volume flow rate Q of the metal melt flowing out of the mold (4) by a second state observer (BEO2) 输出 , considering --The geometric shape A of the mold (4) 横截面 , a plurality of, preferably at least three, temperature values ​​T1 ... T3, wherein a plurality of temperature sensors determine the temperature values ​​T1 ... T3 in the mold (4) in real time during the continuous casting, wherein a plurality of the temperature values ​​(T1 ... T3) are assigned to different material level heights, and - Casting speed v of the at least partially solidified strand, preferably with a plate or slab cross-section C , wherein the strand is at least temporarily released from the mold (4) during the continuous casting and the casting speed v is determined in real time C , - According to the inflow volume flow Q 输入 and the outflow volume flow Q 输出 Calculate the material level h1, in particular by the condition 2. The method according to claim 1, characterized in that The first state observer BEO1 is an incomplete state observer.

3. The method according to claim 2, characterized in that The first state observer BEO1 also takes into account the mass and the preferred geometry of the casting container (1, 1a) as input variables.

4. The method according to any one of the preceding claims, characterized in that The second state observer BEO2 is an incomplete state observer.

5. The method according to claim 4, characterized in that A plurality of the temperature values ​​(T1 . . . T3) are assigned to a first plate (8, 9), preferably a narrow side plate (9), of the mold (4).

6. The method according to claim 5, characterized in that In addition to the plurality of temperature values ​​(T1 . . . T3) of the first plate (8, 9) of the mold (4), the second state observer BEO2 also uses a plurality of temperature values ​​(T1 . . . T3) of the second plate (8, 9) of the mold (4). ‘ …T3 ‘ ), wherein the second plate is preferably arranged opposite to the first plate (8, 9) in the width or thickness direction.

7. The method according to any one of the preceding claims, characterized in that The temperature sensor is an optical fiber temperature sensor.

8. The method according to any one of the preceding claims, characterized in that The mold - in addition to the virtual filling level sensor for observing the filling level height h1 in the first measuring range (7), - also having a physical level sensor for measuring a fill level height h2 of the fluid metal in a second measuring range (6), The second measuring range (6) is smaller than the first range, in particular the first measuring range (7) is at least twice, preferably four times, larger than the second measuring range (6).

9. The method according to claim 8, characterized in that The material level height of the molten metal in the mold (4) in the second range corresponds to the material level height h2 of the physical material level sensor, and the material level height outside the second range corresponds to the material level height h1 of the virtual material level sensor.

10. A virtual filling level sensor for determining a filling level h1 of a metal melt, preferably consisting of steel or an aluminum alloy, in a mold (4) of a continuous casting machine, wherein: The molten metal in the mold (4) forms a casting liquid surface (5) having the material level height h1, and the virtual material level sensor has: - for observing the volume flow Q flowing into the mold (4) 输入 The first state observer BEO1 is connected to a position sensor of a valve (2) for setting the flow rate of the molten metal from the casting container (1, 1a) to the casting pipe (3) in a signal-transmitting manner, wherein the valve is preferably a barrier or a slider, and the position sensor is capable of determining the opening s of the valve in real time during continuous casting. 阀 , - for observing the volume flow Q flowing out of the mold (4) 输出 A second state observer BEO2, wherein the second state observer is connected to the a plurality of, preferably at least three, temperature sensors, wherein the temperature sensors are capable of determining temperature values ​​(T1 . . . T3) assigned to different filling level heights in real time during the continuous casting, and -- Casting speed sensor, wherein the casting speed sensor can determine the casting speed v of the casting billet in real time C ,and - for the volume flow Q according to the inflow 输入 and the outflow volume flow Q 输出 A calculation unit for calculating the material level height h1.

11. A material level measurement system having - a virtual filling level sensor for determining a filling level h1 of a metal melt in a first measuring range (7) according to claim 10, and a physical level sensor for measuring the filling level h2 of the molten metal in the second measuring range (6), in, The second measuring range (6) is smaller than the first measuring range (7), in particular the first measuring range (7) is at least twice, preferably four times, larger than the second measuring range (6).

12. The fill level measuring system according to claim 11, comprising a multiplexer, characterized in that The multiplexer uses - the material level height h1 of the metal melt from the virtual material level sensor, and - the material level h2 of the metal melt from the physical material level sensor (11) as the output variable and input variable of the multiplexer, - if the material level height h1 of the virtual material level sensor is within the second measurement range, the multiplexer uses the material level height h2 of the metal melt from the physical material level sensor (11), If the filling level height h1 of the virtual filling level sensor is outside the second measuring range, the multiplexer uses the filling level height h1 of the metal melt from the virtual filling level sensor.

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