阅读说明：本技术 用于测量熔融金属的温度的装置和方法 (Device and method for measuring the temperature of molten metal ) 是由 G·内延斯 C·拉德勒特 M·因德赫伯格 F·史蒂文斯 于 2021-06-21 设计创作，主要内容包括：本发明涉及一种用于测量熔融金属浴温度的装置,包括：光学芯线；管套,其中所述光学芯线至少部分地布置在所述管套中,所述管套具有在4mm至8mm的范围内的外径和在0.2mm至0.5mm的范围内的壁厚；和多个分隔元件,其包括多于两个分隔元件,所述分隔元件彼此间隔开地布置在管套中,并且在所述多于两个分隔元件的两者之间形成至少一个隔室。本发明还涉及一种用于测量熔融金属浴温度的系统和方法。(The invention relates to a device for measuring the temperature of a bath of molten metal, comprising: an optical core; a jacket tube, wherein the optical core wire is at least partially arranged in the jacket tube, the jacket tube having an outer diameter in the range of 4mm to 8mm and a wall thickness in the range of 0.2mm to 0.5 mm; and a plurality of separation elements comprising more than two separation elements, which are arranged spaced apart from each other in the tube sleeve and form at least one compartment between two of the more than two separation elements. The invention also relates to a system and a method for measuring the temperature of a bath of molten metal.)

1. An apparatus for measuring the temperature of a molten metal bath, comprising:

an optical core;

a jacket tube, wherein the optical core wire is at least partially arranged in the jacket tube, the jacket tube having an outer diameter in the range of 4mm to 8mm and a wall thickness in the range of 0.2mm to 0.5 mm; and

a plurality of separation elements comprising more than two separation elements arranged spaced apart from each other in the tube sleeve and forming at least one compartment between two separation elements of the more than two separation elements.

2. The device of claim 1, wherein the shroud comprises a material having a thermal conductivity greater than 30W/mK at room temperature RT.

3. The apparatus of claim 2, wherein the product of the thermal conductivity of the shroud and the wall thickness is greater than 0.015W/K.

4. The device according to any of the preceding claims, characterized in that the space between the optical core and the jacket is filled with:

a gas, a gas mixture, or

-a filler material comprising a low density material, in particular comprising a low density organic material.

5. The apparatus of claim 4, wherein the filler material comprises cotton, wool, hemp, rice hulls, and/or flax.

6. The apparatus of any one of the preceding claims, wherein the shroud comprises a material or alloy selected from at least one of the following group of materials, the group of materials comprising: iron and/or alloyed steel grade materials.

7. The device according to any one of the preceding claims, characterized in that the separating elements are arranged in the pipe sleeve at a distance from each other which is smaller than the distance from the entry point in the furnace to the height of the molten metal bath.

8. The device of claim 7, wherein the separation element is arranged to form a vent path across a length of the device.

9. The apparatus according to any one of claims 1 to 6, characterized in that the separating elements are arranged in the pipe sleeve at a distance from each other which is greater than the distance from the entry point in the furnace to the level of the molten metal bath.

10. The apparatus of claim 9, wherein the spacer element is arranged in the jacket in a gas-tight manner to provide a seal between the optical core and the interior of the jacket.

11. Device as claimed in any of the claims 1-6, characterized in that the separating elements are arranged in the pipe sleeve at a distance in the range of 2-5 m, preferably at a distance of 3-4 m from each other.

12. Device according to any one of the preceding claims, characterized in that the separation element comprises a silicone, preferably a two-component silicone material, or a rubber material, a leather material, a cork material and/or a metal material.

13. Device according to any one of the preceding claims, characterized in that it comprises at least one sensor at 0.8g/cm³To 4g/cm³A density in the range of (1), especially in the range of 1g/cm³To 3g/cm³A density within the range of (1).

14. A system, comprising:

the device of any one of claims 1 to 13; and

a delivery mechanism for delivering the forward tip of the device into a molten metal bath.

15. A method of measuring the temperature of a molten metal bath using the apparatus of any one of claims 1 to 13 or using the system of claim 14, the method comprising:

conveying the means for measuring temperature, wherein the forward tip is conveyed into the molten metal bath at a conveying speed in the range of 10g/s to 50g/s, in the direction of the molten metal; and

the temperature of the molten metal is measured.

Technical Field

The invention relates to a device for measuring the temperature of a molten metal bath, comprising an optical core and a pipe sleeve. The invention also relates to a system and a method for measuring the temperature of a molten metal bath using a corresponding device.

Background

In metal making processes, there are several methods available for measuring the temperature of a molten metal bath in a metallurgical vessel. One of these methods for measuring the temperature of a molten metal bath, particularly iron or steel in the molten environment of an Electric Arc Furnace (EAF), involves immersing an optical fiber surrounded by a metal jacket in the molten metal. An optical fiber surrounded by a metal jacket is also commonly referred to as an optical core. The optical fiber may receive thermal radiation and may transmit the thermal radiation from the molten metal to a detector, such as a pyrometer. Suitable instruments may be associated with the detector for determining the temperature of the molten metal bath.

To measure the temperature of the molten metal bath, the optical core may be fed into the molten metal bath where the optical core is consumed at a substantially constant rate for continuous temperature measurement over a predetermined period of time. The front tip of the optical core is immersed in a metallurgical vessel, first encountering a hot atmosphere, followed by a slag/slag layer, and then a molten metal bath, as it progresses towards the molten metal bath. Once the temperature measurement is finished, the tip of the optical core wire may be partially retracted from the molten metal bath. Then, the tip of the retracted optical core becomes a new front tip for the next temperature measurement.

EP1857792a1 describes, by way of example, a method and a device for measuring the temperature of a bath of molten metal using an optical core.

Many devices known in the art are typically constructed using optical fibers positioned in a ferrule. The gap between the optical wire and the metal pipe sleeve is typically filled with a filler material to protect the optical wire from the heat of the molten metal bath during immersion. The optical core and the jacket tube may be conveyed into the molten metal bath at the same or different rates and to the same location in the molten metal bath.

However, such a configuration does not always enable reliable measurements over the entire range of applications. Here, the term "application range" may be used to refer to a temperature range in which the temperature measurement of the molten metal bath is performed. In particular, temperature measurements made in the low temperature range combined with high slag temperatures can lead to large differences in output data. For example, common steel grade materials range in temperature from 1520 ℃ to 1700 ℃. However, most of the corresponding measured temperatures are typically between 1550 ℃ and 1620 ℃.

Therefore, there is a need for an apparatus and method by which more accurate temperature measurements can be obtained throughout the range of applications while minimizing the consumption of the apparatus in the molten metal.

Disclosure of Invention

The present invention provides an apparatus for measuring the temperature of a molten metal bath, comprising:

an optical core;

a pipe sleeve, wherein the optical core is at least partially disposed in the pipe sleeve, wherein the pipe sleeve has an outer diameter in a range of 4mm to 8mm and a wall thickness in a range of 0.2mm to 0.5 mm; and

a plurality of separating elements comprising more than two separating elements arranged spaced apart from each other in the tube sleeve and forming at least one compartment/section between two of the more than two separating elements.

Here, the term "optical core" may be used to refer to an optical fiber which may be contained in a housing, in particular a metal jacket. The housing may completely surround the optical fiber or may be at least partially open such that the housing does not completely surround the optical fiber. Furthermore, the housing may be at least partially filled with an agent for application in the molten metal. Furthermore, the optical fiber can be used without a housing.

The jacket of the device may be a metal jacket with the optical core extending along its length. For example, the optical core may be arranged in the center of the metal pipe sleeve and may extend in the direction of the metal pipe sleeve.

According to the invention, the pipe sleeve has:

an outer diameter in the range of 4mm to 8mm, and

a wall thickness in the range of 0.2mm to 0.5 mm.

The wall thickness of the pipe sleeve is preferably in the range of 0.3mm to 0.4 mm. Furthermore, tests in the molten metal bath have shown that the accuracy of the temperature measurement is related to the quality of the cold material entering the molten metal bath during the temperature measurement. The mass per unit time depends on the feed rate and the geometry of the apparatus.

Furthermore, the device comprises a plurality of separation elements comprising more than two separation elements arranged in the tube sleeve and forming at least one compartment between two separation elements of said more than two separation elements.

Here, the term "compartment" relates to the volume/space between the different separating elements in the pipe sleeve.

Here, the term "separating element" relates to a component arranged within the jacket for dividing the volume within the jacket.

The separation element may be realized as a disc-shaped element arranged within the jacket comprising an opening through which the optical core extends and which opening may at least partly support the optical core. The opening is preferably located in the middle of the element to support the optical core in the center of the tube sleeve. However, in an example, the separating element may also have a different shape. For example, the separating element may have a cubic, cylindrical, conical, triangular, spherical, pyramidal, trapezoidal and/or polygonal shape. In one example, the device includes a plurality of spacer elements including at least five spacer elements disposed in the tube sleeve.

The spacer elements may be connected to either the optical core or the jacket tube and may advantageously minimize friction between the jacket tube and the optical core as they are arranged between the optical core and the jacket tube, thereby avoiding stress/pressure. Further, the optical core and the jacket tube may move together when the device is fed into the molten metal. Thus, relative movement of the optical core and the jacket tube can be minimized or even avoided when fed into the molten metal bath.

The speed and position of the optical core and the jacket can be substantially the same.

Advantageously, by using a separation element to create a compartment between at least any two separation elements, penetration of molten metal into the pipe sleeve can be effectively prevented.

Advantageously, by using the device as described above, the pipe sleeve melts from the immersion end in a controlled manner, which results in a more accurate temperature measurement. The actual temperature measurement can be made when the pipe sleeve is melted in the molten metal bath.

By using the apparatus as described above, the pipe sleeve advantageously does not melt before entering the molten metal bath. Furthermore, the pipe sleeve does not melt from the side, which minimizes the penetration of molten metal into the pipe sleeve, which can adversely affect temperature measurements.

For example, when the device is inserted into a molten metal bath, the gas contained in the compartment may expand due to the temperature increase. In one example, the pressure required to increase to prevent steel ingress may be calculated by simply calculating the ferrostatic pressure in the molten metal bath at the target immersion depth.

However, a sudden increase in the temperature of the molten metal bath may produce a pressure build-up of about 6bar in these compartments. This pressure may cause cracks on the side walls of the pipe sleeve before the melting process begins.

Furthermore, it has been shown that minimizing the mass per unit length by reducing the diameter and wall thickness of the sleeve, as described above, helps to obtain more accurate temperature measurements. Furthermore, a minimum diameter is advantageous in order to enter the molten metal bath without bending and floating.

In one example, the shroud comprises a material having a thermal conductivity greater than 30W/mK at Room Temperature (RT).

Here, the term room temperature RT may be used to refer to a temperature of about 20 ℃, in particular a temperature in the range of 16 ℃ to 25 ℃.

In one example, the space between the optical core and the jacket is filled with:

a gas, a gas mixture, or

-a filler material comprising a low density material, in particular comprising a low density organic material.

The space may be filled with air or an inert gas, for example. In order to minimize the entry of molten metal into the pipe sleeve, which would lead to low output values, the filling material can advantageously be arranged at least partially in the space between the optical core and the pipe sleeve.

Here, the term "low density" may be used to refer to a material having a density of less than 2g/cm³Preferably less than 1g/cm³。

In one example, the filler material includes cotton, wool, hemp, rice hulls, and/or flax. Other low density filler materials having an ash content of less than 10% are also suitable.

The ash content may represent the non-combustible components remaining after complete combustion of the material.

In one example, the pipe sleeve comprises a material or alloy selected from at least one of the following group of materials, the group of materials comprising: iron and/or alloyed steel grade materials.

Advantageously, the above materials have a thermal conductivity higher than 30W/mK at room temperature.

In one example, the product of the thermal conductivity and the wall thickness of the shroud is greater than 0.015W/K.

High thermal conductivity in combination with thin walls may be advantageous. The product of wall thickness in mm and thermal conductivity may advantageously be higher than 0.015W/K. In one example, an outer wall having a thickness of 0.3mm requires a material having a thermal conductivity greater than 50W/mK.

Advantageously, the higher the thermal conductivity of the jacket material selected, the more uniform the temperature distribution during heating of the jacket. In contrast, uneven temperature distribution may result in uncontrolled bursting of the shroud sidewalls, resulting in undesirable ingress of molten metal.

In a typical furnace, the distance between the entry point and the molten metal bath is in the range of 1 to 2 m.

In one example, the separating elements are arranged in the pipe sleeve at a distance from each other which is smaller than the distance from the entry point in the furnace to the level of the molten metal bath. In this example, the separation element may be arranged to form a vent path spanning the length of the device.

In one example, the separating element comprises a silicone (preferably a two-component silicone material), a rubber material, a leather material, a cork material and/or a metal material.

In order to overcome the adverse effect of the sudden pressure increase, small compartments may be selected, which means that at least one compartment is transported into the furnace during the measurement. Due to thermal expansion, the gas in this compartment will expand and the pressure will increase. Advantageously, the aeration path prevents the ingress of steel and slag from the side walls of the shroud. During immersion of the device, the inflation gas may be evacuated through the immersed end portion of the device.

In another example, the separating elements are arranged in the pipe sleeve at a distance from each other which is greater than the distance from the entry point in the furnace to the level of the molten metal bath.

In this case the next/adjacent compartment is arranged partly inside the furnace and partly outside the furnace. Advantageously, this may prevent the gas from being heated over the entire compartment length and thus reduce the maximum pressure obtained in the compartment to overcome the adverse effect of the sudden increase in pressure. Furthermore, in the aforementioned example, the separating element may be arranged in a gas-tight manner in the jacket tube to provide a seal between the optical core and the inside of the jacket tube.

In another example, the separating elements are arranged in the pipe sleeve at a distance from each other in the range of 2m to 5m, preferably 3m to 4 m.

In most metallurgical processes, the molten metal bath is covered by a layer of slag having a lower density than the molten metal bath. For example, in a steelmaking process, the molten steel has a density of about 7g/cm³The density of the slag covering is about 2g/cm³. In the processing stages of converters, electric arc furnaces and ladle furnaces, the result is CO (carbon monoxide)/CO₂The (carbon dioxide) bubbles cause slag foaming and this density is further reduced. If the device is denser than the metal bath it will tend to sink to the bottom, whereas at lower densities it will tend to float.

In one example, the device is included at 0.8g/cm³To 4g/cm³In the range, especially in the range of 1g/cm³To 3g/cm³Density within the range.

To prevent the risk of floating during immersion of the device, at 0.8g/cm³To 4g/cm³In the range, especially in the range of 1g/cm³To 3g/cm³A material density in the range is advantageous.

The electric arc furnace process can have a very wide range of slag densities. The estimated slag thickness in the collapse phase is about 30cm, which can rise to the roof of the furnace during foaming. Therefore, the devices used in this process need to be adapted to this range to obtain accurate temperature measurements.

The invention also relates to a system comprising a device as described herein and a delivery device for delivering the forward tip of the device into a molten metal bath. The system may further include a furnace having an entry point for the apparatus and containing a molten metal bath and a slag cover.

The invention also relates to a method of measuring the temperature of a molten metal bath using the apparatus or system described herein, comprising:

conveying the means for measuring temperature, wherein the forward tip is conveyed into the molten metal bath at a conveying speed in the range of 10g/s to 50g/s, in the direction of the molten metal; and

the temperature of the molten metal is measured.

The transport speed of 50g/s can be considered as the maximum value. In high temperature applications, this velocity needs to be applied to achieve sufficient depth in the molten metal bath. In low temperature applications, this value may be lower. In all steel making applications, a minimum of 10g/s is required to achieve a minimum immersion depth.

For example, the most accurate measurements can be obtained at a delivery rate of about 30g/s in an electric arc furnace application, about 20g/s in a ladle furnace application, and about 16g/s in a ladle application.

As previously mentioned, it can be seen that the accuracy of the temperature measurement is related to the quality of the cold material entering the molten metal bath during the temperature measurement. The mass per unit time depends on the feed rate and the geometry of the apparatus.

Advantageously, by conveying the device as described above at a conveying speed defined in the method, a more accurate temperature measurement can be obtained.

In one example, the optical core and the jacket tube are fed together into a molten metal bath at the same speed.

Two advantageous examples are described below:

in the first example, the feed rate required to obtain accurate temperature measurements was verified. An optical fiber comprises an optical core and a core having an outer diameter of 6mm, a wall thickness of 0.3mm, and a density of about 1.6g/cm³The mild steel pipe sleeve of (1) can be fed into the molten metal bath at a speed of 800mm/s to a depth of 300 mm. About 1.6g/cm³The density of (A) corresponds to a mass of 44.1 g/m. At this speed, the measurement will be accurate over the entire range of applications. Advantageously, the selected structure will remain in the molten metal and will float towards the molten metal-slag interface.

With respect to the first example, the following example parameters are obtained:

time 300mm/800mm/s 0.375s

Mass 44.1g/m 0.3m 13.2g

Mass/time 13.2g/0.375s 35.2g/s

In a second example, the maximum transport speed at which accurate temperature measurements are obtained is determined. The density of the low carbon steel pipe sleeve with the outer diameter of 7mm and the wall thickness of 0.4mm is about 2.2g/cm³(equivalent to 68.6g/m) and can be fed into the molten metal bath at a maximum speed of 728mm/s to a depth of 400 mm. At this speed, the measurement is reliable over the entire range of applications. The selected structure will remain in the molten metal and will float towards the molten metal-slag interface.

With respect to the second example, the following example parameters are obtained:

mass 68.6g/m 0.4m 27.4g

Time 27.4g/50g/s 0.54s

The speed is 400mm/0.54s 728 mm/s.

Drawings

The basic idea of the invention will be described in more detail below with reference to an embodiment shown in the drawings. Here:

FIG. 1 shows a schematic diagram of a system for measuring the temperature of a molten metal bath according to an embodiment of the present invention;

FIG. 2 shows a schematic position-time curve depicting the immersion state of the front tip of the device before, during and after the measurement of the molten metal temperature;

FIGS. 3A, 3B show schematic views of devices according to a first and a second embodiment of the invention;

FIG. 4 shows a schematic view of a system for verifying the hermeticity of a compartment according to an embodiment of the present invention;

figures 5A to 5C show a schematic view of an apparatus according to a first embodiment of the invention immersed in a bath of molten metal;

figures 6A to 6C show schematic views of different configurations of a separating element according to an embodiment of the invention; and

fig. 7A to 7C show schematic views of an apparatus according to an embodiment of the invention.

Detailed Description

Fig. 1 shows a schematic diagram of a system for measuring the temperature of a molten metal bath 15 according to an embodiment of the invention.

As shown in fig. 1, the system comprises a device 1, which device 1 is at least partly located on a coil 9 and at least partly deployed from the coil 9 for taking measurements. The first end of the apparatus 1 is connected to a pyrometer 11, which pyrometer 11 may in turn be connected to a computer system (not shown) for processing data obtained with the apparatus 1. As shown in fig. 1, the apparatus 1 is transported by the transport device 13 through the guide tube sleeve 17 into a vessel which has an entry point 19 and contains the molten metal bath 15. The temperature of the part of the device 1 extending from the coil 9 to the entry point 19 can be considered low, which may be in the temperature range from room temperature up to 100 ℃. Once passing through the entry point 19 in the direction of the molten metal bath 15, it first encounters a hot atmosphere that can reach 1700 ℃ or even higher, followed by a layer of slag 16 followed by the molten metal bath 15. The entry point 19 of the vessel may be provided with a lance (not shown in figure 1) to prevent metal and furnace contaminationSlag is drilled into the apparatus 1. The forward tip of the apparatus 1 immersed in the molten metal bath 15 will melt and temperature measurements can be obtained during this melting phase. The front tip of the device 1, inside the molten metal 15, comprises a length L_MMAnd (4) showing. After the measurement has been carried out, the part of the device 1 which is located in the hot atmosphere and extends through the slag layer 16 can be conveyed back in the direction of the coil 9 and can be reused for the next measurement. The front tip of the device 1 comprises a length in the interior of the container denoted L in fig. 1_MEASAnd (4) showing. Also shown in FIG. 1 are the slag layer-atmosphere interface, SAI, and the molten metal-slag layer interface, MSI.

Fig. 2 shows a schematic of a position-time curve showing the state of immersion of the front tip of the device before, during and after the measurement of the temperature of the molten metal. For illustrative purposes, the position-time diagram of fig. 2 shows a simplified case in which it is assumed that the front tip of the device is not melted during the measurement. The entry points shown in fig. 1 are considered as entry points and measured reference points for the container. Fig. 2 shows the length L comprised by the front tip inside the container_MEASAnd a length L included in the molten metal_MMAnd the length L of the apparatus normally consumed in order to perform a measurement_C. This procedure/sequence/process ends with the new front tip of the device positioned at the container entry point. A length L of the device_MMImmersed in the molten metal bath 15, the distance of forward feed minus the length in the molten metal bath to obtain the return distance.

Fig. 3A and 3B show schematic views of a device 1, 1' according to a first and a second embodiment of the invention during a measurement procedure. Fig. 3A and 3B show a portion of the apparatus being transported into the molten metal bath 15 from an entry point 19.

In both embodiments, the device 1,1 'comprises more than two separating elements 7a, 7 a', 7b ', 7 n' arranged in the pipe sleeve 5,5 ', which form at least one compartment/section between the two separating elements 7a, 7 a', 7b ', 7 n'.

Fig. 3A shows a device 1 according to a first embodiment, comprising a configuration with large compartments. With the configuration according to the first embodiment, the separating elements 7a, 7b are arranged in the jacket tube 5 around the optical core 3 at a distance from one another which is greater than the distance from the entry point 19 to the molten metal-slag layer interface MSI. In the illustrated construction, the length of the compartment is selected such that no closed compartment is located in the container over its entire length. In case the entry point 19 is equipped with a blow pipe (not shown) a small part of the interior of the vessel can be considered cold. As shown in fig. 3A, a compartment is formed between two separating elements 7a, 7b, wherein a first separating element 7a is in the cold region and an opposite second separating element 7b is in the hot region.

Fig. 3B shows a device 1' according to a second embodiment, comprising a configuration with small compartments. The separating elements 7a ', 7 b', 7n 'are arranged in the pipe sleeve 5' at a distance from one another which is smaller than the distance from the entry point 19 in the furnace to the molten metal-slag layer interface MSI. In the embodiment shown in fig. 3B, the separating elements 7a ', 7B ', 7n ' are at least partially permeable to gas to form a venting path (not shown in fig. 3B) from the immersed end towards the coil.

Fig. 4 shows a schematic view of a system for verifying the airtightness of the compartments formed by the separating elements 7a, 7B, 7a ', 7 n' arranged in the sleeves 5,5 'of the devices 1, 1' shown in fig. 3A and 3B.

The system shown for verifying the gas tightness comprises a pressure regulator 21, a flow meter 23, a valve 25 and a pressure gauge 27. For testing, either of the devices 1, 1' shown can be connected to the system. However, the skilled person knows that there are also alternative means available for verifying the airtightness of the compartment.

In order to obtain accurate measurements, at least the compartments of the device 1 having a large compartment structure should be airtight. The "tightness" of the compartments can be tested by testing the tightness of the individual separation elements 7a, 7a ', 7 n' to show a counter/back pressure of 0.8 bar. From experience it can be said that the longer the length of the compartment, the higher this pressure should be. It has been shown that at a counter pressure higher than 0.9bar, a chamber length of up to twice the length of the hot zone shows advantageous results. Separating the elements with organic compounds may form a gas in the hot zone. These separation elements may burn and form a venting path during the measurement process. According to tests on a device 1 'comprising 20 separating elements, the device 1' shown connected to the system in fig. 4 may show a counter pressure of 0.2 to 0.8 bar. The device 1 shown next to the device 1' in fig. 4 may show a counter pressure of more than 0.9bar, which is based on tests performed with a device 1 comprising a single separation element.

As an example, a method of verifying hermeticity using the system shown in fig. 4 is described below with subsequent steps:

1. with the valve 25 closed, the pressure regulator 21 is set to 1bar overpressure;

2. the valve 25 is opened and the flow meter 23 is set to 5l/m (liter/min);

3. connecting the samples 1, 1' to the system; and

4. the pressure on the pressure gauge 27 is measured.

Fig. 5A-5C show schematic views of a device 1 according to a first embodiment. In particular, fig. 5A-5C illustrate a portion of the apparatus 1 being transported into the molten metal bath 15 from an entry point 19. The figure shows exemplarily three stages of immersion of the device 1 in the bath 15 of molten metal from the left-hand side to the right-hand side.

In fig. 5A, the partition element 7b is shown in a hot atmosphere. The penetration of metal and slag into the front tip of the device 1 can be prevented by means of the spacer element 7 b. Since the front tip can be aerated into the molten metal bath 15 and the next/adjacent compartment is arranged partly in the cold region, high pressures in the pipe sleeve 5 can be prevented. After the measuring procedure, the core wire portion in the molten metal bath 15 will melt and with the next measuring procedure the new front tip of the device 1 will be positioned as shown in fig. 5B. Likewise, the partition element 7b avoids the penetration of metal and slag and, since the compartment is partially arranged in the cold zone, reduces the overpressure in the next compartment. After the procedure shown in fig. 5B is finished, the new front tip will be positioned as shown in fig. 5C. During this measuring procedure, the separating element 7b will enter the molten metal bath 15 and the pipe sleeve 5 will melt before the internal pressure in the compartment becomes too high. After the procedure shown in fig. 5C is finished, the next measurement will again be similar to the procedure shown in fig. 5A.

Fig. 6A-6C show schematic views of different configurations of the separating element 7, 7', 7 "according to embodiments of the invention. Those skilled in the art will appreciate that in the examples described herein, different configurations may be used together/jointly inside the sleeve.

In fig. 6A, a gas-permeable separating element 7 is shown, which separating element 7 has a vent path 8 (not shown in fig. 6A) arranged around the central opening of the optical core. The illustrated construction allows the optical core to move relative to one another during the bending and straightening of the device during the delivery procedure.

In fig. 6B, a gas-permeable separating element 7 'is shown, which separating element 7' has a venting path 8 'arranged in the surface of the separating element 7', wherein the separating element 7 'is in contact with the sleeve of the device when the separating element 7' is mounted in the sleeve.

In fig. 6C, a gas-permeable separating element 7 "is shown, wherein the venting path 8" is formed by selecting a gas-permeable material.

Fig. 7A-7C show schematic views of a device 1, 1', 1 "according to an embodiment of the invention. The arrows in each figure indicate the direction of immersion of the device 1, 1', 1 "into the molten metal bath (not shown in figures 7A to 7C).

Fig. 7A shows a device 1, which device 1 has a filling material 4 arranged in the space between the jacket 5 and the optical core 3. The filler material 4 may be a low density material such as cotton.

Fig. 7B shows the device 1 ' whereby the vent path 8 ' is formed by a hole arranged in the outer circumference of the optical core 3 '.

Fig. 7c shows a device 1 ", which device 1" has separating elements 7a ", 7 b" which are able to provide a gas-tight seal, and additional separating elements 7c ", 7 d" which are arranged between the separating elements 7a ", 7 b" and which are not in direct contact with the pipe sleeve 5 ".

Reference numerals

1, 1' device

3, 3' optical core

4 filling material

5, 5' pipe sleeve

7-7 ', 7a-7 n' separating element

8, 8' ventilation path

9 coil

11 pyrometer

13 conveying mechanism

15, 15' molten metal bath

16, 16' slag layer

17 guide tube sleeve

19 entry point

21 pressure regulator

23 flow meter

25 valve

27 pressure gauge

SAI slag layer-atmosphere interface

MSI molten metal-slag layer interface

L_MEASMeasuring length

L_MMLength in molten metal

L_CLength of apparatus consumed in molten metal