Abstract
A device for measuring a temperature of a molten metal bath, comprising: an optical cored wire; a tube, wherein the optical cored wire is at least partly arranged in the tube, wherein the tube has an outer diameter in the range of 4 mm to 8 mm, and a wall-thickness in the range of 0.2 mm to 0.5 mm; and a plurality of separating elements comprising more than two separating elements arranged in the tube spaced apart from each other, and forming at least one compartment between two of the more than two separating elements.
The invention also relates to a system and method for measuring a temperature of a molten metal bath.
Claims
1. A device for measuring a temperature of a molten metal bath, comprising: an optical cored wire; a tube, wherein the optical cored wire is at least partly arranged in the tube, wherein the tube has an outer diameter in the range of 4 mm to 8 mm, and a wall-thickness in the range of 0.2 mm to 0.5 mm; and a plurality of separating elements comprising more than two separating elements arranged in the tube spaced apart from each other, and forming at least one compartment between two of the plurality of separating elements.
2. The device of claim 1, wherein the tube comprises a material having a thermal conductivity higher than 30 W/mK at room temperature.
3. The device of claim 2, wherein the product of thermal conductivity and wall-thickness of the tube is greater than 0.015 W/K.
4. The device of claim 1, wherein a space between the optical cored wire and the tube is filled with: a gas or a gas mixture, or a filler material comprising a low density material.
5. The device of claim 3, wherein the filler material comprises cotton, wool, hemp, rice husks and/or flax.
6. The device of claim 1, wherein the tube comprises a material or an alloy of at least one of iron and an alloyed steel grade.
7. The device of claim 1, wherein the separating elements are arranged in the tube spaced apart from each other at a distance which is smaller than the distance from an entry point in the furnace to a height of the molten metal bath.
8. The device of claim 7, wherein the separating elements are arranged to form a ventilation path over the length of the device.
9. The device of claim 1, wherein the separating elements are arranged in the tube spaced apart from each other at a distance which is larger than the distance from an entry point in the furnace to the height of the molten metal bath.
10. The device of claim 9, wherein the separating elements are arranged in the tube in a gas-tight manner to provide a seal between the optical cored wire and the inside of the tube.
11. The device of claim 1, wherein the separating elements are arranged in the tube spaced apart from each other at a distance in the range of 2 meters (m) to 5 m.
12. The device of claim 1, wherein the separating elements comprise a silicone material, a rubber material, a leather material, a cork material, and/or a metal material.
13. The device of claim 1, wherein the device comprises a density in the range of 0.8 g/cm.sup.3 to 4 g/cm.sup.3.
14. A system, comprising: a device according to claim 1; and feeding means for feeding a leading tip of the device in a molten metal bath.
15. A method for measuring the temperature of a molten metal bath, using a device according to claim 1, comprising: feeding the device for measuring the temperature with a leading tip directed towards the molten metal with a feeding rate in the range of 10 g/s to 50 g/s into the molten metal bath; and measuring the temperature of the molten metal.
16. A method for measuring the temperature of a molten metal bath, using a system according to claim 14, comprising: feeding the device for measuring the temperature with a leading tip directed towards the molten metal with a feeding rate in the range of 10 g/s to 50 g/s into the molten metal bath; and measuring the temperature of the molten metal.
17. The device of claim 4, wherein the low density material is an organic material.
18. The device of claim 1, wherein the separating elements are arranged in the tube spaced apart from each other at a distance in the range of 3 m to 4 m.
19. The device of claim 1, wherein the device comprises a density in the range of 1 g/cm.sup.3 to 3 g/cm.sup.3.
Description
[0069] The idea underlying the invention shall subsequently be described in more detail with respect to the embodiments shown in the figures. Herein:
[0070] FIG. 1 shows a schematic view of a system for measuring a temperature of a molten metal bath according to an embodiment of the invention;
[0071] FIG. 2 shows a schematic position-time graph indicating the immersion of a leading tip of the device, before, during and after measuring the temperature of the molten metal;
[0072] FIGS. 3A, 3B show schematic views of devices according to a first embodiment and a second embodiment of the invention;
[0073] FIG. 4 shows a schematic view of a system for verifying the gas-tightness of the compartments according to embodiments of the invention;
[0074] FIGS. 5A-5C show schematic views of immersing a device according to a first embodiment of the invention into a molten metal bath;
[0075] FIGS. 6A-6C show schematic views of different configurations of separating elements according to embodiments of the invention; and
[0076] FIGS. 7A-7C show schematic views of devices according to embodiments of the invention.
[0077] FIG. 1 shows a schematic view of a system for measuring a temperature of a molten metal bath 15 according to an embodiment of the invention.
[0078] As shown in FIG. 1, the system comprises a device 1 which is located at least partly on a coil 9 and is at least in part unwound from the coil 9 for conducting a measurement. A first end of the device 1 is connected to a pyrometer 11 which in turn could be connected to a computer system (not shown) to process the data obtained with the device 1. As shown in FIG. 1, the device 1 is fed by means of a feeder 13 through a guide tube 17 in a vessel having an entry point 19 and containing the molten metal bath 15. The temperature of a part of the device 1 extending from the coil 9 to the entry point 19 can be considered to be low, which could be a temperature ranging from room-temperature up to 100° C. Once passing the entry point 19 in the direction of the molten metal bath 15, a hot atmosphere of up to 1700° C. or even higher is first encountered, followed by a slag layer 16 which is in turn followed by the molten metal bath 15. The entry point 19 to the vessel could be equipped with a blowing lance (not shown in FIG. 1) to prevent metal and slag-penetration into the device 1. The leading tip of the device 1 submerged into the molten metal bath 15 will melt and during this melting stage the temperature measurement can be obtained. The distance covered by the leading tip of the device 1 inside the molten metal 15 is indicated by L.sub.MM. After the measurement is taken, the part of the device 1 located in the hot atmosphere and extending through the slag layer 16 can be fed back into the direction of the coil 9 and can be reused for the next measurement. The distance covered by the leading tip of the device 1 inside the vessel is indicated by L.sub.MEAS in FIG. 1. Also shown in FIG. 1 are the Slag Layer—Atmosphere Interface, SAI, and the Molten Metal—Slag Layer Interface, MSI.
[0079] FIG. 2 shows a schematic of a position-time graph indicating the immersion of the leading tip of the device, before, during and after measuring the temperature of the molten metal. For the sake of the present explanation, the position-time graph of FIG. 2 shows a simplified case, where it is assumed that the leading tip of the device is not melting during the measurement. The entry point which is shown in FIG. 1 is considered to be the entry point of the vessel and a point of reference for the measurement. The distance covered inside the vessel L.sub.MEAS is shown in FIG. 2 as well as the distance covered by the leading tip inside the molten metal L.sub.MM and the length of the device that is typically consumed for taking one temperature measurement L.sub.C. The sequence will end with a new leading tip of the device positioned at the entry point of the vessel. The length of the device L.sub.MM immersed in the molten metal bath 15 and the feedforward distance is reduced with the length in the molten metal bath to obtain the return distance.
[0080] FIGS. 3A and 3B show schematic views of devices 1, 1′ according to a first embodiment and a second embodiment of the invention during a measurement sequence. FIGS. 3A and 3B show a part of the device that is fed from the entry point 19 in the molten metal bath 15.
[0081] In both embodiments the devices 1, 1′ comprise more than two separating elements 7a, 7a′, 7b, 7b′, 7n′ arranged in the tube 5, 5′ which form at least one compartment between two of the separating elements 7a, 7a′, 7b, 7b′, 7n′.
[0082] FIG. 3A shows a device 1 according to a first embodiment having a configuration with large compartments. For the configuration according to the first embodiment, the separating elements 7a, 7b are arranged in the tube 5 around the optical cored wire 3 spaced from each other at a distance which is larger than the distance from the entry point 19 to the Molten Metal—Slag Layer Interface, MSI. In the shown configuration, the length of the compartment is chosen in such a way that no closed compartment is positioned in the vessel over its entire length. In case the entry point 19 is equipped with a blowing lance (not shown), a small part inside the vessel can be considered as cold. As shown in FIG. 3A the compartment is formed between two separating elements 7a, 7b with a first separating element 7a in a cold area, and an opposite second separating element 7b in a hot area.
[0083] FIG. 3B shows a device 1′ according to a second embodiment having a configuration with small compartments. Here, the separating elements 7a′, 7b′, 7n′ are arranged in the tube 5′ spaced from each other at a distance 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 that is shown in FIG. 3B the separating elements 7a′, 7b′, 7n′ are at least partly gas permeable for forming a ventilation path from the immersion end into the direction of the coil (not shown in FIG. 3B).
[0084] FIG. 4 shows a schematic view of a system for verifying the gas-tightness of the compartments formed by the separating elements 7a, 7b, 7a′, 7n′ arranged in the tubes 5, 5′, of the devices 1, 1′ shown in FIGS. 3A and 3B.
[0085] The shown system for verifying the gas-tightness comprises a pressure regulator 21, a flowmeter 23, a valve 25 and a pressure meter 27. For testing, either one of the shown devices 1, 1′ can be connected to the system. However, the skilled person would know that there are also alternative means available for verifying the gas-tightness of the compartments.
[0086] To obtain accurate measurements at least the compartments of the device 1 having the configuration with large compartments should be gastight. The “gas-tightness” of the compartments can be tested by testing the gas-tightness of the individual separating elements 7a, 7a′, 7n′ to show a counter-pressure of at 0.8 bar. As a rule of thumb, it can be said that the longer the length of the compartment, the higher this pressure should be. It has been shown that chamber lengths up to the double length of the length in the hot zone show favorable results with a counter-pressure above 0.9 bar. Separating elements with organic compounds may cause gas formation in the hot zone. These separating elements may burn during the measurement sequence and create a ventilation path. Device 1′ which is shown in FIG. 4 as connected to the system, may show a counter-pressure of 0.2 to 0.8 bar based on testing a device 1′ comprising 20 separating elements. Device 1 which is shown in FIG. 4 next to device 1′, may show a counter pressure of >0.9 bar based on a test with a device 1 comprising a single separating element.
[0087] As an example, a method for verifying the gas-tightness using the system shown in FIG. 4 is described below with the subsequent steps: [0088] 1. Set pressure regulator 21 to 1 bar overpressure with valve 25 closed; [0089] 2. Open valve 25 and set flow meter 23 to 5 l/min; [0090] 3. Connect specimen 1, 1′ to the system; and [0091] 4. Measure pressure on the pressure meter 27.
[0092] FIGS. 5A-5C show schematic views of a device 1 according to the first embodiment. In particular, FIGS. 5A-5C show a part of the device 1 that is fed from the entry point 19 in the molten metal bath 15. From the left hand side to the right hand side three stages of immersing the device 1 into the molten metal bath 15 are exemplarily shown in the figures.
[0093] In FIG. 5A it is shown that a separating element 7b is positioned in the hot atmosphere. Metal and slag penetration into the leading tip of the device 1 can be prevented by means of the separating element 7b. High pressure in the tube 5 can be prevented, because the leading tip can ventilate into the molten metal bath 15 and the next compartment is arranged partly in the cold zone. After the measurement sequence the part of the cored wire in the molten metal bath 15 will be molten and with the next measuring sequence the new leading tip of the device 1 will be positioned as shown in FIG. 5B. Again, metal and slag penetration are avoided by the separating element 7b and overpressure in the next compartment is reduced since the compartment is partly arranged in the cold area. After the sequence shown in FIG. 5B is concluded, the new leading tip will be positioned as shown in FIG. 5C. During this measurement sequence the separating element 7b will enter the molten metal bath 15 and the tube 5 will melt before the internal pressure in the compartment will become too high. After the sequence shown in FIG. 5C is concluded, the next measurement will again resemble the sequence shown in FIG. 5A.
[0094] FIGS. 6A-6C show schematic views of different configurations of separating elements 7, 7′, 7″ according to embodiments of the invention. The skilled person would know that in examples described herein, different configurations can be used together inside a tube.
[0095] In FIG. 6A a separating element 7 is shown which is gas permeable and which has a ventilation path 8 arranged around a central opening for the optical cored wire (not shown in FIG. 6A). The shown configuration allows relative movement of the optical cored wire during the bending and straightening of the device during the feeding sequence.
[0096] In FIG. 6B a separating element 7′ is shown which is gas permeable and which has a ventilation path 8′ arranged in the surface of the separating element 7′, where the separating element 7′ is in contact with the tube of the device when installed inside the tube.
[0097] In FIG. 6C a separating element 7″ is shown which is gas-permeable, wherein the ventilation path 8″ is created by choosing a material being gas permeable.
[0098] FIGS. 7A-7C show schematic views of devices 1, 1′, 1″ according to embodiments of the invention. An arrow in each one of the figures indicates the immersion direction of the devices 1, 1′, 1″ into the molten metal bath (not shown in FIGS. 7A-7C).
[0099] FIG. 7A shows a device 1 having a filler material 4 arranged in the space between the tube 5 and the optical cored wire 3. The filler material 4 could be a material having a low density such as cotton.
[0100] FIG. 7B shows a device 1′, whereby the ventilation path 8′ is created by means of apertures arranged in the outer diameter of the optical cored wire 3′.
[0101] FIG. 7C shows a device 1″ having separating elements 7a″, 7b″ that can provide a gas-tight seal and additional separating elements 7c″, 7d″ arranged between separating elements 7a″, 7b″ that are not in direct contact with the tube 5″.
LIST OF REFERENCE NUMERALS
[0102] 1, 1′, 1″ Device
[0103] 3, 3′, 3″ Optical Cored Wire
[0104] 4 Filler Material
[0105] 5, 5′, 5″ Tube
[0106] 7-7″, 7a-7n″ Separating Elements
[0107] 8, 8′, 8″ Ventilation Path
[0108] 9 Coil
[0109] 11 Pyrometer
[0110] 13 Feeder
[0111] 15, 15′ Molten Metal Bath
[0112] 16, 16′ Slag Layer
[0113] 17 Guide Tube
[0114] 19 Entry Point
[0115] 21 Pressure Regulator
[0116] 23 Flow meter
[0117] 25 Valve
[0118] 27 Pressure Meter
[0119] SAI Slag Layer—Atmosphere Interface
[0120] MSI Molten Metal—Slag Layer Interface
[0121] L.sub.MEAS Measurement Distance
[0122] L.sub.MM Distance in Molten Metal
[0123] L.sub.C Length of Device Consumed in Molten Metal
