Measuring probe for molten metal

Abstract

To provide an improved measuring probe for measuring at least one parameter of molten metal, and in particular, provide an improved measuring probe with a reduced response time.SOLUTION: The present invention relates to a measuring probe for molten metal, comprising a sensor unit adapted to determine at least one parameter of the molten metal, a signal line connected to the sensor unit, and a carrier element. The sensor unit comprises a sensing element and a metal body. The signal line comprises at least two wires, and an inner diameter of a carrier tube is 7 to 20 times an outer diameter of the wires.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a measuring probe for determining at least one parameter of a molten metal. In a further embodiment, the present invention relates to a method for measuring at least one parameter of a molten metal.

[0002] In metal manufacturing processes, particularly those used in the steel industry, several parameters of the molten metal, such as the chemical properties of the bath or the temperature of the molten metal, are crucial for controlling the metallurgical process. The ability to continuously and / or periodically monitor these variables is highly desirable for both economic and quality reasons. Accurate monitoring can significantly reduce energy consumption due to overheating and material consumption due to overprocessing. Other advantages of continuous monitoring include the ability to measure high-temperature phase changes, chemical reactions, and other related phenomena.

[0003] Methods and apparatus for determining these process-related parameters are known in the art and, in most cases, involve the use of disposable probes equipped with at least a sensor. Typically, the probe is placed beneath the surface of the molten material in the form of a drop-in sensor or by a lance assembly. The lance assembly can be operated manually, fully automatically, or semi-automatically. The probe is typically connected to a processing unit for processing the recorded data by wire or cable, although wireless data transfer has also been described. The data is collected and processed in real time or near real time, providing the metallurgical equipment operator with important information about the progress or status of the metal manufacturing process taking place in the vessel.

[0004] In drop-in sensor measurements, a disposable probe is dropped into a container holding the molten material. Suitable probes are disclosed, for example, in European Patent Publication No. 0758445(A1) and European Patent Publication No. 0997716(A1). Such probes include a metal measuring head attached to one end of a carrier tube. The measuring head is typically made of cast iron or steel to provide the mass necessary to penetrate the slag layer deposited on top of molten steel or molten iron. A signal cable connected to the measuring system is wound within the carrier tube and unwinds from the carrier tube when the carrier tube is dropped into the molten metal. A sensor unit, including at least one sensor, e.g., a temperature sensor and / or an electrochemical element for measuring the oxygen activity of the molten metal, is located within the measuring head. Typical response times for commonly used sensors range from 5 to 10 seconds. Since response time is a determinant of the requirements for all other components of the probe, a reduction in response time is desirable.

[0005] Probes applied to BOF vessels (basic oxygen furnaces) typically have a mass of several kilograms and hold up to 30 meters of cable. The cable used is selected and fitted to survive the required travel time and withstand molten metal for at least the required response time of the sensor. Cables used in metallurgical applications can withstand this environment for more than 10 seconds and have an outer diameter of 9-10 mm. The cable consists of 2-3 wires covered with an outer insulating layer of rubber material, electrically insulated from each other, with an insulating layer thickness of 2.5-3 mm. The space required for the cable determines the dimensions of the carrier tube and also the mass of the measuring head. This mass must be sufficient to obtain a speed that is enough to pull the cable out of the tube and move it into the metal bath without increasing the travel time. Overall, such probes have a mass of 6-8 kg, of which the measuring head (the assembly immersed during the measurement sequence) accounts for about 50%. This material requirement increases the material cost associated with these probes, and it is desirable to reduce this cost factor.

[0006] In current practice, the sensor is introduced from a relatively high position above the container holding the molten metal, typically in the range of 10-20 m above the molten metal level. Several probes can be stored in a magazine, and one probe is released from the magazine at a time for each measurement. The probe free-falls, accelerated by gravity, and sinks into the molten metal. Therefore, the final velocity of the probe when it reaches the molten metal surface is determined by the distance between the drop station and the molten metal. To obtain reliable measurement data, the probe needs to have a certain mass so that it sinks deep enough below the molten surface. Further components, such as a balance body to maintain the probe's balance, are necessary to provide reliable data or enable measurement, and these components are not related to the recording of the measurement itself. Therefore, drop-in sensors introduce a relatively large amount of extraneous material into the molten material being measured. Furthermore, the immersion point cannot be reliably controlled.

[0007] Molten metal is typically covered with a slag layer during manufacturing, which exposes any probe or sensor passing through it to harsher conditions, regardless of the specific method used. Therefore, it is desirable to minimize the exposure time as much as possible.

[0008] In particular, in the field of electric arc furnaces (EAFs), there are currently only a limited number of methods available for determining the parameters of the molten metal that can be performed during vessel operation. EAFs produce steel by using an electric arc to melt one or more charges placed inside the furnace, such as scrap metal, molten iron, ferrous materials, or other moltenable materials. A common procedure in EAFs involves the operator manually inserting a lance equipped with appropriate sensors into the furnace through a slag door, a relatively wide opening in the furnace shell wall. Such an insertion process is highly undesirable as it disturbs the environment inside the vessel during the metallurgical process. Furthermore, energy is wasted when the slag door is opened, as cold ambient air is drawn in through it. Due to the design of EAFs, where the electrodes are positioned above the metal bath, standard drop-in probes cannot be applied to these facilities.

[0009] Recent developments have made sensors with shorter response times available, such as needle-shaped oxygen sensors. However, the state-of-the-art designs of drop-in sensors cannot utilize the improvements achieved in probes. Considering conventional technology, an improved measuring probe with a shorter response time is needed. Furthermore, the probe needs to have a simplified design so that it can be manufactured at low cost.

[0010] Therefore, an object of the present invention is to provide an improved measuring probe for measuring at least one parameter of molten metal that solves at least one of the above-mentioned problems. In particular, one object is to provide an improved measuring probe with a reduced response time.

[0011] A further aspect of the object of the present invention is to provide a measuring probe that enables simplification of the hardware required to use the probe.

[0012] A further object of the present invention is to provide a measuring probe that can be accelerated before measurement is performed.

[0013] Furthermore, an object of the present invention is to provide a measuring probe that can be introduced to a measurement point, in particular, through an available inlet point of a metallurgical vessel in an electric arc furnace (EAF).

[0014] Another aspect of the present invention provides a method for measuring at least one parameter of molten metal or slag using the measuring probe of the present invention, which allows for parameter determination while reducing labor and costs with respect to equipment, control techniques, and organization, and at the same time improving the reliability and quality of the obtained measurements.

[0015] These objectives are achieved by the subject matter as defined in the independent claims.

[0016] The present invention is a measuring probe for molten metal, - A sensor unit adapted to determine at least one parameter of molten metal, Sensing elements and, A sensor unit including a metal body that at least partially surrounds the sensing element, - A signal line including at least two individual wires connected to the sensor unit, - Career elements, The present invention provides a measuring probe characterized in that the inner diameter of the carrier tube is 7 to 20 times the outer diameter of the individual wires.

[0017] Surprisingly, in a measuring probe with individual wires and an optimized ratio of wire diameter to carrier dimensions, it was found that signal wire rewinding was improved when measurements were taken. Furthermore, the probe was particularly well-suited for acceleration and exhibited stable flight characteristics. Surprisingly, it was observed that both factors resulted in a more reliable measuring probe. Moreover, the individual wires allow for a minimal sensor unit design, and the sensor unit can be accelerated and / or immersed without applying excessive force to the signal wire.

[0018] The measuring probe of the present invention is not intended to be used in combination with a lance, i.e., it should be understood that the probe should not be immersed below the surface of the molten metal by auxiliary articles. The measuring probe of the present invention is particularly suitable for being provided at the inlet point of a metallurgical vessel, from which the part or parts that need to be immersed in the molten metal to obtain measurement values, particularly the sensor unit, fall towards the molten metal or are actively accelerated.

[0019] The measuring probe can be used in almost all metallurgical vessels. Particularly in an EAF, when the size is small, the available inlet points can be used, and there is an additional advantage that it is not necessary to open the slag door to obtain measurement values. Furthermore, it is possible to minimize the interruption of the metallurgical equipment to obtain the required parameters, and particularly this method is applicable during continuous operation. Thereby, the total operating cost, particularly the required energy input, is minimized, and the throughput of the metallurgical equipment and the quality of the products produced are improved.

[0020] The present invention relates to a measuring probe for molten metal. The molten metal typically has a temperature exceeding 600 °C, particularly exceeding 800 °C, preferably exceeding 1000 °C. The temperature of the molten metal can be, for example, in the range of 600 to 1800 °C, more preferably in the range of 800 to 1700 °C.

[0021] Preferably, the molten metal is molten steel. The terms "melt" or "molten metal" do not exclude the presence of any solid or gaseous parts, such as the non-molten parts of the respective metals. The temperatures of metal melts are different and are usually determined according to the composition of the metal and the stage of the melting process.

[0022] The molten metal may be covered with a slag layer. The term "slag" refers to a non-steel by-product that is often produced in steelmaking furnaces and typically exists as molten material floating on top of the molten metal. Slag may include metal oxides, metal sulfides, calcium oxide, magnesium oxide, magnesite, dolomite, iron oxide, aluminum oxide, manganese oxide, silica, sulfur, phosphorus, or combinations thereof. To obtain reliable measurements, the sensor introduced into the molten metal must pass through the slag layer as quickly as possible before reaching the final measurement point in the molten metal, minimizing the effects of heat and corrosion and the solidification of the slag material on the cold sensor unit. Such a solidified layer must melt by the time the sensor finally reaches the molten metal before reliable measurements can be taken, thus increasing the time the sensor needs to withstand the decomposition environment of the molten metal.

[0023] This invention relates to a measuring probe. The measuring probe should be understood as a device equipped with a sensor unit that can be at least partially immersed in a liquid whose parameters are to be determined, and in relation to this invention, the liquid in question is molten metal, i.e., a high-temperature liquid. Before measurement, the sensor unit of the measuring probe must be placed below the surface of the molten metal. The method of immersing the sensor unit in the molten metal is not further limited; for example, the sensor unit may be dropped from a stationary point on the molten metal, or accelerated by appropriate means in addition to gravity. The compact design of the measuring probe of this invention allows for adaptation to various methods and enables diverse applications of the measuring probe. Preferably, the sensor unit is accelerated not only by gravity but also by, for example, a pneumatic accelerator.

[0024] A measurement sequence using the measurement probe of the present invention typically involves separating the sensor unit from the carrier element, and then immersing the sensor unit in the molten metal of interest.

[0025] The measuring probe includes a sensor unit adapted to determine at least one parameter of the molten metal. The sensor unit is, in principle, configured as a disposable component that dissolves or decomposes in the molten metal after the parameter of interest has been determined. Components of the sensor unit may already be dissolved before or during the determination of the parameter.

[0026] The parameters may be physical, chemical, or metallurgical parameters, such as temperature, the presence, activity, and / or concentration of the compound, particularly oxygen activity, carbon content, aluminum content, or chemical composition.

[0027] In this specification, "determining a parameter" may be used as a synonym for "measuring a parameter." A parameter may be determined from a single-point measurement or from multiple-point measurements. This determination may include determining a single parameter or determining a combination of multiple parameters. For example, this determination may include measuring the oxygen activity or temperature of a molten metal. This determination may also include measuring both oxygen activity and temperature.

[0028] The sensor unit includes a sensing element. It should be understood that the sensing element is adapted to determine at least one parameter of the molten metal. The sensing element may be at least one selected from the group consisting of, for example, electrochemical sensors, electromagnetic sensors, optical sensors, thermoelectric sensors, sensors for detecting voltage, sensors for detecting current, or sensors for detecting electrical resistance. The sensor unit may also include multiple sensing elements, preferably any combination of any of the specified sensing elements, thereby enabling the measurement of several parameters in combination. Therefore, “sensing element” should be understood in this application as “at least one sensing element.”

[0029] Thermoelectric sensors are preferably provided as thermocouples. As is known to those skilled in the art, a thermocouple comprises two wires of different materials (also called thermocouple legs), which are typically joined at one end, called a thermal junction. Such thermocouples may be housed within a protective element, such as a tube, preferably a quartz glass sheath. Depending on the type of thermocouple, such a quartz glass sheath may be, for example, at least one tubular or U-shaped quartz glass sheath.

[0030] In a preferred embodiment, the thermocouple is a quartz glass-sheathed thermocouple. The quartz glass-sheathed thermocouple may include an outer closed-end tube and an inner open-end tube disposed within the outer closed-end tube, preferably both tubes being quartz glass tubes. The first leg of the thermocouple is located within the inner open-end tube, and the second leg of the thermocouple is located in the hollow space between the inner open-end tube and the outer closed-end tube.

[0031] In an alternative embodiment, the thermocouple is provided without a sheath. In such a case, the thermocouple is preferably coated with a refractory material, at least partially.

[0032] An electrochemical cell typically comprises a solid electrolyte material, a reference material, and an electrode. An electrochemical cell, particularly one for determining oxygen activity, may include a solid electrolyte tube with one end closed, the closed end containing the reference material and the electrode. Such a sensor is disclosed, for example, in U.S. Patent Application Publication No. 2002100686(A1). An electrochemical cell can also be provided as a needle sensor comprising a conductive wire that functions as an electrode having at least a solid electrolyte coating and a reference material coating. Such a sensor is disclosed, for example, in U.S. Patent No. 5332449(A).

[0033] Preferably, the sensor unit includes a thermocouple and / or an electrochemical cell for measuring the temperature of the molten metal, preferably an electrochemical cell for determining the oxygen activity of the molten metal.

[0034] The sensor unit may include a bath contact. The bath contact should be understood as a conductive means that provides an electrical contact between the sensor unit and the molten metal. The bath contact may be made of metal, such as molybdenum (Mo) or steel. The bath contact may be ring-shaped or rod-shaped, and preferably is ring-shaped.

[0035] A preferred sensor unit includes a needle sensor for determining oxygen activity, a thermocouple (preferably a thermocouple enclosed in a quartz glass sheath), and a ring-shaped bath junction surrounding the thermocouple. Such a sensor unit has a compact and robust design, which allows for miniaturization of the measuring probe on which the sensor unit is mounted.

[0036] Another preferred sensor unit includes a needle sensor for determining oxygen activity, a thermocouple having a fire-resistant coating, and a ring-shaped bath junction surrounding the needle sensor and thermocouple. Such a sensor unit has a compact and robust design, which allows for miniaturization of the measuring probe on which the sensor unit is mounted.

[0037] Preferably, the sensor unit is configured to provide at least one signal to a processing unit. Such a processing unit is configured to process at least one signal to determine the parameters of the molten metal.

[0038] Preferably, the response time of the sensing element is less than 5 seconds, more preferably less than 3 seconds. If the sensor unit includes multiple sensing elements, it is particularly preferable that the response time of all sensing elements is less than 5 seconds, and more preferably less than 3 seconds. The response time is the time required from the time the sensing element is introduced into the molten metal whose parameters are to be determined until a constant and stable measurement signal can be obtained. Sensing elements using the latest technology include, for example, thermocouples with a typical response time of 6 to 8 seconds in molten steel, or electrochemical cells that determine oxygen activity with a typical response time of 8 to 10 seconds in molten steel. Therefore, by utilizing sensing elements with faster response times, it becomes possible to utilize components with reduced mass and shielding.

[0039] The response time of a sensing element is primarily determined by the heat capacity of its active region. Sensing elements with a small active region have a smaller heat capacity in that region, resulting in a shorter response time. The active region of a sensing element should be understood as the section of the sensing element where the desired signal is generated. For example, in the case of a thermocouple, the active region is the thermal junction, and in the case of a needle-shaped oxygen sensor, the active region is the tip of the needle. In preferred embodiments, the diameter of the active region of the sensing element is less than 2.5 mm, preferably less than 2 mm. For example, the diameter of the active region of the sensing element may be in the range of 0.3 mm to 2.5 mm, preferably 0.5 mm to 2 mm.

[0040] The sensor unit includes a metal body that at least partially surrounds the sensing element. The metal body is provided by a sheath so that the sensing element remains operational during immersion of the immersion probe and throughout the measurement period. Furthermore, the metal body aligns the sensor unit so that, once immersed, the sensing element has a suitable orientation and measurement position for determining the parameter under consideration. Furthermore, the metal body preferably surrounds the connection between the sensing element and the signal line, further protecting these sensitive and critical components of the sensor unit.

[0041] The metal body has two ends. The end of the metal body where the sensing element is located is called the immersion end, and the opposite end along the longitudinal axis of the metal body is called the rear end. The metal body surrounds the sensing element at least partially. In other words, the sensing element extends partially outward from the immersion end of the metal body.

[0042] Preferably, the metal body is made of a material with high heat capacity. In preferred embodiments, the metal body is made of steel, stainless steel, cast iron, or copper. Before reliable measurements can be taken, the active area of ​​the sensing element must reach thermal equilibrium with the molten metal, and the metal body must be protected for a sufficiently long time until this point can be reached. Most preferably, the metal body is made of copper, at least partially. Because copper has high thermal conductivity, it can reach thermal equilibrium more quickly, which enables high-speed measurements. Copper is not usually considered a suitable material for such a metal body because it can be mixed into the molten material being processed. In the present invention, the metal body can be miniaturized in such a way that the introduced contaminants can be ignored.

[0043] Preferably, the mass of the sensor unit is less than 500g, more preferably less than 400g, even more preferably less than 300g, and most preferably less than 200g. The mass of the sensor unit should be understood as the total mass of the sensing element and the metal body, as well as any further optional components of the sensor unit. In other words, the mass of the sensor unit refers to all components of the sensor unit enclosed by the outer contour of the sensing element and the metal body. For example, the mass of the sensor unit is in the range of 80-500g, more preferably 100-400g, even more preferably 120-300g, and most preferably 140-200g. The mass of the measuring head of currently used drop-in sensors, including the metal body and sensor element, is in the range of 3-4kg. A sensor unit with significantly reduced mass minimizes the amount of material introduced into the molten metal during measurement, and further reduces production costs through material savings. Furthermore, the measurement is minimally affected by the cold mass introduced by the lightweight sensor unit, resulting in more reliable and accurate data.

[0044] Preferably, the length of the metal body is 70 mm or less, more preferably 60 mm or less, and even more preferably 50 mm or less. The length of the metal body may also be in the range of 20 to 70 mm, more preferably 30 to 60 mm. The length of the metal body should be understood as the length along the central longitudinal axis from the immersion end to the rear end.

[0045] Preferably, the diameter of the metal body is 40 mm or less, more preferably 35 mm or less, and even more preferably 30 mm or less. The diameter of the metal body may be in the range of, for example, 10 to 40 mm, more preferably 15 to 35 mm. The diameter of the metal body should be understood as the diameter perpendicular to the central longitudinal axis from the immersion end to the rear end.

[0046] Preferably, the density of the metal body is higher than the density of the molten metal. Typically, the density of molten steel is about 7.0 g / cm³. 3 Preferably, the density of the metal body is 7.2 g / cm³. 3Higher, more preferably 7.6 g / cm 3 Higher. The density of the metal body is, for example, 7.2 to 8.8 g / cm 3 In the range, more preferably 7.6 to 8.6 g / cm 3 It may be in the range.

[0047] Preferably, the ratio of the mass of the sensor unit to the net density of the sensing element and the metal body is 100 cm 3 Or less, more preferably 70 cm 3 Or less, and even more preferably 50 cm 3 Or less. For example, this ratio is 15 to 100 cm 3 In the range, more preferably 20 to 70 cm 3 Or 20 to 50 cm 3 It may be in the range. In a state-of-the-art drop probe with an average mass of 3500 g, this ratio is typically higher than 400 cm 3 It has been found that minimizing the ratio enables a compactly designed sensor unit and improves the overall response time of the sensor unit provided by the sensing element.

[0048] In a preferred embodiment, the density of the immersion end of the metal body is higher than the density of the rear end. Advantageously, the sensing element is oriented in the vertical direction when immersed in the molten metal. The density gradient of the metal body, which decreases towards the rear end, supports such orientation.

[0049] The metal body may be a monolithic component or may include a plurality of components. The modular design of the metal body enables control of the density distribution within the metal body and may facilitate its manufacture.

[0050] The metal body may be a hollow body having a tubular structure, and preferably, the metal body has a cylindrical structure symmetric along a central longitudinal axis extending from the immersion end to the rear end. It should be understood that the metal body includes a central void.

[0051] Preferably, the maximum cross-sectional area of ​​the central void in the metal body is less than 25% of the maximum total cross-sectional area of ​​the metal body, and more preferably less than 20%. The cross-sectional area should be understood as the area of ​​the cross-section perpendicular to the central longitudinal axis from the immersion end to the rear end. Because the area ratio of the void is small, sufficient density of the metal body is ensured.

[0052] The metal body may include multiple cross-sectional areas along its length; for example, the metal body may include shoulders at the immersion end and / or rear end; in other words, the metal body may include recessed sections on the outer circumference of its ends, and therefore the cross-sectional area of ​​these sections or any section thereof is reduced.

[0053] The central void may include a constant cross-sectional area along the length of the metal body, or it may include sections with different cross-sectional areas. For example, the central void may include an annular step. Such a modular or stepped design of the void may be advantageous for assembling the sensor unit, as the sensing element can be fixed within the central void. For example, the metal body may include a plurality of cylinders arranged in a line with each other in the axial direction, each having an internal bore that decreases in diameter towards the rear of the metal body.

[0054] The sensor unit may include a housing that encloses a sensing element or a plurality of sensing elements. Preferably, the housing encloses the connection between the sensing element and the signal line. Such a housing can reinforce the connection and further facilitate the assembly of the sensor unit. The housing may include a body of fire-resistant material such as fire-resistant cement, adhesive filler, and / or a metal support.

[0055] In a preferred embodiment, the sensing element, preferably at least one sensing element enclosed in a housing, fills the void in the metal body; in other words, the sensing element or the housing surrounding at least one sensing element is at least partially molded to fit into the central void of the metal body. This further enhances the compact design of the sensor unit and avoids low-density voids. Furthermore, no additional filling elements are required as a solution to increase the total density of the drop-in probe, as disclosed, for example, in European Patent Publication No. 0758445(A1).

[0056] Preferably, the combined net density of all components enclosed by the outer contour of the sensing element and the metal body is higher than the density of the molten metal. The combined net density of all components enclosed by the outer contour of the sensing element and the metal body should be understood as the combined density of these components, i.e., the density of the entire construction block, which may also include voids or further elements (e.g., electrical contact elements or housings of the sensing element) enclosed by the metal body. Hereinafter, for brevity, this parameter will be referred to as the combined net density of the sensing element and the metal body. In a preferred embodiment, the combined net density of the sensing element and the metal body is at least 5% higher, more preferably at least 8% higher, and even more preferably more than 10% higher than the density of the molten metal. The combined net density of the sensor unit and the metal body is 7.2 g / cm³ 3 Higher, and more preferably, 7.5 g / cm³ 3 A higher, and more preferably 7.8 g / cm³ 3 It may be higher. The net density of the metal body combination is, for example, 7.2 to 8.6 g / cm³. 3 The range, more preferably 7.6 to 8.4 g / cm³ 3 It may be within the range of . In a preferred embodiment, the combined net density of the sensing element and the metal body is at least 80%, more preferably at least 90%, of the density of the metal body.

[0057] In a preferred embodiment, the proportion of the void surrounded by the sensing element and the metal body is less than 20%, more preferably less than 15%, and most preferably less than 10% of the net external volume of the sensing element and the metal body. The void surrounded by the sensor unit is a cavity having a density of less than 20% of the combined net density of the sensing element and the metal body. The net external volume of the sensing element and the metal body should be understood as the volume surrounded by the outer contours of the sensing element and the metal body.

[0058] Preferably, the sensor unit does not include any additional mass components or buoyancy components. Low-mass sensor units are particularly well-suited for acceleration and therefore reach high speeds before being immersed in the molten metal bath, eliminating the need for such further balancing. Thus, the design of the sensor unit can be simplified and miniaturized. This miniaturization further makes it possible to introduce the sensor unit into the metallurgical vessel through available entry points (whereas conventional drop-in sensors or lance systems are too large).

[0059] The sensor unit may include an electrical contact element, which is adapted to connect the sensor unit to a suitable means for transferring measured data, typically a signal line. Such a contact component facilitates the installation of the sensor unit, ensures stable contact to the signal line, and reduces the force on the sensing element. Preferably, the bath contact and the sensing element are electrically connected to the electrical contact element.

[0060] Advantageously, the electrical contact elements are placed entirely within the metal body, particularly within the central void of the metal body.

[0061] The measuring probe includes a signal line connected to the sensor unit. The signal line is adapted to transfer the signal acquired by the sensor unit, particularly the sensing element, to a suitable processing unit, or a transfer means adapted to transfer the signal to such a processing unit. In other words, the signal line preferably provides a connection between the sensor unit and the processing unit.

[0062] Preferably, the signal line is connected to the rear end of the sensor unit, preferably by an electrical contact element. The rear end of the sensor unit should be understood as the end where the rear end of the metal body is located. The signal line extends from the connection section, which is the part connected to the signal unit, to the rear section, which is the opposite side.

[0063] The signal line comprises at least two individual wires, or in other words, the signal line comprises at least two single wires not enclosed in a common cable sheath. In relation to the present invention, the wires should typically be understood as conductive cores made of a metallic material, such as rubber or silicone material, embedded in an insulating sheath. The conductive cores may comprise a plurality of single fibers or filaments. The cable should be understood as a plurality of wires enclosed in a common cable sheath. Surprisingly, it has been found that using individual wires improves the unwinding behavior of the signal line from the carrier element, and further improves the free-flight phase of the sensor unit when the sensor unit is directed towards molten metal. Furthermore, a single wire has less mass, and therefore can reduce the mass of the sensor unit that needs to pull the signal line during free-flight.

[0064] The signal line must meet several requirements. It must withstand the measurement environment for a sufficiently long time until the sensor unit reaches the measurement point and the required data is obtained. Furthermore, the signal line must be compatible with the method of immersion of the sensor unit, for example, to allow for acceleration of the sensor unit. Especially in methods involving a free-flight phase of the probe, the signal line must support control of this phase without interference. Therefore, the flexibility and material of the signal line must be selected accordingly.

[0065] The metallic material can be selected from the group including copper (Cu), copper-nickel (CuNi), Chromel (a nickel (Ni) alloy containing chromium (Cr)), and Alumel (a nickel (Ni) alloy containing aluminum (Al), manganese (Mn), and silicon (Si)). In a preferred embodiment, the wire includes a copper (Cu) or copper-nickel (CuNi) conductive core. The cross-sectional area of ​​the conductive core is 0.05 to 3 mm². 2 Preferably 0.1 to 2.5 mm 2 It may also be within that range.

[0066] Suitable materials include, for example, rubber, preferably silicone rubber or EPDM (ethylene propylene diene monomer) rubber. Preferably, the insulating sheath material does not completely melt when in contact with the molten material, but preferably decomposes at least partially into inorganic material. Such decomposition behavior allows for longer protection of the conductive core of the wire, and therefore extends the lifespan of the signal line before failure. Preferably, the insulating material is silicone rubber.

[0067] Preferably, the outer diameter of the individual wires is less than 3 mm, more preferably less than 2 mm, and even more preferably less than 1 mm. For example, the outer diameter of the individual wires is in the range of 0.2 to 3 mm, more preferably 0.4 to 2 mm, and even more preferably 0.3 to 1 mm. The outer diameter of the wire refers to the cross-sectional area perpendicular to the longitudinal length of the wire passing through the conductive core and insulating sheath. Wires commonly used in state-of-the-art sensor units typically have a diameter greater than 4 mm, which results in relatively high rigidity. Wires that can be used in the sensor unit according to the present invention can have a smaller diameter, resulting in greater flexibility. Such flexibility has been shown to be advantageous for the stability of the connection between the signal line and the sensor unit. Furthermore, it allows for a more compact design of the entire measuring probe, particularly the carrier element.

[0068] In a preferred embodiment, the ratio of the diameter of the active region of the sensing element to the diameter of the individual wires is in the range of 1-1 to 1-4, preferably in the range of 1-2 to 1-3. This region ratio ensures that the individual wires are matched to the response time of the sensing element.

[0069] Preferably, the density of the signal wire is lower than the density of the molten metal. In such a configuration, the signal wire generates buoyancy when the sensor unit is immersed in the molten metal, supporting the vertical alignment of the sensor unit during measurement. Preferably, the density of the signal wire is within the range of the density of the slag layer covering the molten metal, typically about 1.8 g / cm³ on average. 3 This configuration generates buoyancy in the portion of the signal wire immersed in the molten metal, while gravity acts in the opposite direction on the portion located in the slag layer. Preferably, the density of the signal wire is 5 g / cm³. 3 Less than 4 g / cm³, more preferably 4 g / cm³ 3 It is less than . The density of the signal lines is, for example, 1-5 g / cm³. 3 In the range of 2-4 g / cm³, more preferably 2-4 g / cm³. 3 It may also be within that range.

[0070] In a preferred embodiment, the signal line density is lower than the combined net density of the sensing element and the metal body. The signal line density has been found to advantageously correspond to the combined net density of the sensing element and the metal body. The balance between the densities of these components improves the sinking and rising behavior when the sensor unit is immersed in molten metal for measurement, and further supports the vertical alignment of the sensor unit during measurement. Preferably, the signal line density is 50% or less, more preferably 40% or less, and even more preferably 30% or less of the combined net density of the sensing element and the metal body.

[0071] A signal line may consist of a single section or multiple sections connected to one another. The sections should be understood as containing the same material.

[0072] It should be understood that the length of the signal line is selected to be long enough to bridge the distance from the measurement point of the sensor unit to the processing unit, or at least to the connection means that transmits the signal from the sensor unit.

[0073] The sensor unit may include a steering element. The steering element adjusts the balance of the sensor unit during the free flight phase while immersed, thereby improving the behavior of these components during this movement phase. Furthermore, the steering element can provide additional support to the signal lines, ensuring that the signal lines are neatly rewound during the movement phase of the sensor unit in the measurement sequence.

[0074] The steering element is preferably located on or at the rear end of the metal body of the sensor unit.

[0075] The steering element may be an elongated component, such as a wire-shaped element. The steering element may be made of metal, such as copper, steel, or stainless steel. In a preferred embodiment, the steering element is a steel wire. The diameter of the steel wire may be in the range of 0.3 to 3 mm, preferably in the range of 0.8 to 2.5 mm.

[0076] The length of the steering element may be in the range of 5 to 25 cm, preferably in the range of 10 to 20 cm.

[0077] In a preferred embodiment, the first section of the signal line is laid in at least one loop along the steering element. Such loop-shaped guidance of the signal line provides a certain amount of extra length that moves with the signal unit as soon as the signal unit moves, ensuring a stable connection between the signal line and the sensor unit. Preferably, the length of the first section of the signal line is no more than five times, preferably no more than three times, the length of the steering element.

[0078] The signal wire loop may be secured to the steering element by appropriate fastening means, such as clips or paper tape. Preferably, only one leg of the loop of the first section of the signal wire is secured to the steering element. Such single-leg securing allows for more balanced movement of the sensor unit with the steering element during use.

[0079] Another aspect of the present invention is a sensor assembly comprising a sensor unit having a steering element and a signal line connected to the sensing element of the sensor unit.

[0080] The embodiments of the present invention that relate to the sensor unit, steering element, and signal line of the measurement probe described above are also preferred embodiments of the sensor assembly of the present invention.

[0081] The measuring probe includes a carrier element. The carrier element is preferably a hollow body, such as a tube, preferably a cardboard tube, and is configured to hold and / or house the other components of the measuring probe. Such a carrier element protects and holds the other components of the measuring probe before use.

[0082] The signal wire may be wound within the carrier element. For example, the signal wire may pass inside the carrier tube and be wound in at least one layer around its longitudinal axis inside the carrier tube. Preferably, the signal wire is wound in a loop having a diameter in the range of 7 to 20 times, preferably 8 to 15 times, the outer diameter of the individual wire. The loop diameter refers to the outer diameter of the loop. If the signal wire is wound in multiple layers, the diameter refers to the outer diameter of the inner layer. The inner layer should be understood as the layer having the greatest distance from the inner surface of the carrier element.

[0083] The inner diameter of the carrier element is 7 to 20 times the outer diameter of the individual wires of the signal line, preferably 8 to 15 times the outer diameter of the individual wires. Surprisingly, it has been shown to be advantageous, especially when the carrier element is a tube, when the outer diameter of the individual wires of the signal line corresponds to the inner diameter of the carrier element. Such a ratio ensures sufficient fixation of the signal line within the carrier element, while still allowing unraveling control without requiring additional tensile force.

[0084] Preferably, the outer diameter of each individual signal wire is less than 3 mm, and the inner diameter of the carrier element is 7 to 20 times the outer diameter of the individual wires. Such a correlation has been found to be advantageous for the compact design of the measuring probe while still ensuring sufficient stability of the signal wire configuration within the carrier element.

[0085] Preferably, the inner diameter of the hollow body of the carrier element is in the range of 20 to 60 mm, more preferably in the range of 25 to 50 mm.

[0086] The sensor unit is preferably separable from the carrier element. In other words, the sensor unit may be mounted in or on the carrier element in a removable manner. When in use, the signal line can be routed from behind the carrier element and the sensor unit can be released from the carrier element and immersed in the molten metal. It should be understood that the signal line is not released from the sensor unit and remains connected at least until the measurement sequence is complete.

[0087] For example, the measuring probe may include a first coupling component configured to releasably engage with a second coupling component located on or within the sensor unit. The measuring probe may also include a catch element that releases the sensor unit when a certain force is applied.

[0088] The sensor unit may be placed at least partially within the carrier element. The end of the carrier element in which the sensor unit is placed is called the front end of the carrier element, and the opposite end is called the rear end of the carrier element.

[0089] The measuring probe may include a retaining element that enables a mechanism to release the sensor unit from the carrier element. The retaining element may be fixed to the carrier element or configured to engage releasably with one end of the sensor unit. The retaining element may include at least one opening for signal lines.

[0090] The measuring probe may include a fixed element positioned within the carrier element. The fixed element is configured to properly secure and organize the signal wire within the carrier element. Depending on the length of the signal wire, it may be necessary to adjust the deceleration of the signal wire. This can be achieved by increasing the tensile force required to detach the last portion of the rear section of the signal wire from one or more windings. The fixed element further relieves the tensile force from the signal wire to the sensor unit and connecting elements during probe immersion.

[0091] Preferably, the anchoring element is located at the rear end of the carrier element. In a preferred embodiment, the anchoring element is located on the signal line, in other words, the signal line extends at least partially between the interior of the carrier element and the anchoring element. The anchoring element may include an opening configured to allow the signal line to pass freely. Such an opening allows the signal line to slide freely as the winding is unwound by free fall.

[0092] The fixing element may be provided, for example, as a ring having an opening through which a signal wire can pass.

[0093] The measuring probe may include a probe contact element adapted to connect to the rear section of the signal line. Such an electrical connection element may preferably be adapted to be located within a carrier element, for example, a plug-type element.

[0094] Preferably, the probe contact element is adapted to transfer the signal line to the processing unit, for example, by wired or wireless transmission.

[0095] The measuring probe may include protective elements. Such protective elements protect the sensor unit from damage caused by impacts to the molten metal surface during handling. Preferably, the measuring probe may include a protective cap formed from a material that melts or dissolves in the molten metal, at least surrounding the sensor unit. The protective elements may be made of, for example, aluminum or copper, preferably copper.

[0096] The protective element is preferably located on the immersion side of the sensor unit or on the immersion side, preferably on the immersion end of the metal body of the sensor unit. Therefore, the protective element is the first part of the sensor unit that comes into contact with the molten metal when the sensor unit is immersed.

[0097] The protective element may have a conical or frustoconical shape. The conical or frustoconical shape improves the flight behavior of the immersion probe and reduces the frictional force when the probe is immersed in the molten metal.

[0098] The protective element may include openings, such as circular, elliptical, or slit-shaped openings. Such openings enhance the melting behavior of the protective element, particularly in the case of a protective element provided as a metal cap.

[0099] In another aspect, the present invention relates to a method for measuring at least one parameter of molten metal or slag using the measuring probe of the present invention. i) A step of providing a measuring probe, ii) A step of separating the sensor unit from the carrier element, iii) The step of immersing the sensor unit in molten metal, iv) The step of measuring at least one parameter of the molten metal may be included.

[0100] The steps in this method are performed in a given sequential order.

[0101] The embodiments of the present invention relating to the measurement probe described above are also preferred embodiments of the method of the present invention.

[0102] The measuring probe of the present invention has been found to be particularly suitable for further acceleration. Surprisingly, accelerating the sensor unit not solely by gravity offers several advantages. The mass, dimensions, and number of components of the probe housing the sensor unit can be reduced. Reduced material demand leads to lower costs, and the amount of impurities introduced into the molten metal is also reduced. This miniaturization of the sensor and measuring probe makes it possible to introduce the sensor unit through a reduced-size opening that was previously unusable for probe introduction using state-of-the-art methods.

[0103] The method according to the present invention includes separating the sensor unit from the carrier element. In other words, the sensor unit is released from the carrier element of the measuring probe before immersion of the sensor unit. This separation can be achieved, for example, by a release mechanism provided on the measuring probe and / or by corresponding release means provided by an external device.

[0104] The method according to the present invention involves immersing a sensor unit in molten metal, in other words, the sensor unit enters the molten metal from the surface of the molten metal. If a slag layer is present in the molten metal, the sensor unit passes through this slag layer before entering the molten metal.

[0105] This method involves measuring at least one parameter of the molten metal. It should be understood that the measurement is performed when the sensor unit is immersed beneath the surface of the molten metal. In this specification, "measuring" is used to describe the step of obtaining determination of at least one parameter. This step may include measuring a single data point, or it may include measuring multiple data points, i.e., a series of data points. Measuring may include additional steps, such as transmitting the data to a processing unit and / or processing the data.

[0106] This method may include further steps. For example, this method may include the step of accelerating the sensor unit toward molten metal by a suitable accelerating means, such as a pneumatic accelerator.

[0107] After measuring the parameters, further steps may follow, such as releasing or disconnecting components of the measurement probe or cutting any remaining cables.

[0108] The following schematic diagrams illustrate aspects of the invention to further understand the invention in relation to some illustrative figures. However, it should be understood that the invention is not limited to the exact arrangements and means shown. The elements in the drawings are not necessarily to scale with respect to one another. Similar reference numbers indicate corresponding similar parts. [Brief explanation of the drawing]

[0109] [Figure 1] This is a schematic cross-sectional view of the measuring probe. [Figure 2] The sensor unit is shown in more detail. [Figure 3] This shows an example setup for measurement using a measuring probe. [Figure 4] This shows a sensor assembly having a sensor unit that includes a steering element.

[0110] Figure 1 shows a cross-sectional view of the measuring probe 1. The probe 1 includes a cardboard tube as a carrier element 2 on which the signal wire 3 is wound. The sensor unit 4 is at least partially mounted at one end inside the carrier tube 2 and held by a release mechanism 5. Inside the sensor unit 4, the sensing element 6 is embedded in a copper body 7. To protect the sensing element 6 during handling of the measuring probe 1, a protective cap 8 made of a material that melts or molten in molten metal surrounds the sensing element 6. The protective cap 8 may be made of copper, for example. The signal wire 3 is wound onto a winding 9 along the inside of the carrier tube 2. One end of the signal wire 3 is connected to the sensor unit 4, and the other end of the signal wire 3 is connected to a probe contact element 10 at the rear end of the carrier tube 2. The probe contact element 10 can provide a suitable connection point to an extension cable or to means for wirelessly transmitting the signal acquired by the sensor unit 4 to a processing unit.

[0111] Figure 2 shows a more detailed cross-sectional view of the sensor unit 4. The sensor unit 4 includes a needle-shaped oxygen measuring cell 21 and a thermocouple 22 as sensing elements. Therefore, when the sensor unit 4 comes into contact with a molten metal, it can measure the oxygen activity and temperature of the molten metal. The needle cell 21 is, for example, a molybdenum (Mo) pin, which is coated with a layer of a chromium-chromium dioxide mixture (Cr-Cr2O3) as a reference material under a layer of stabilized zirconium oxide (stabilized zirconia) as a solid electrolyte. The diameter of the tip of the oxygen sensor is in the range of 0.5 to 2 mm. Suitable thermocouples are, for example, type B, type D, type G, or type C thermocouples, of which type C thermocouple (W / Re) alloy (95 wt% W / 5 wt% Re to 74 wt% W / 26 wt% Re) containing tungsten-rhenium legs is preferred. The diameter of the thermocouple's thermal junction is 2 mm or less to ensure a fast response time. Both sensing elements (21, 22) are enclosed in a ring-shaped bath contact 23. The sensing elements (21, 22) are connected to an electrical connector 24, to which a signal line 3 is also connected. The connection between the sensing elements (21, 22) and the electrical connector 24 can be secured by a housing 25 made of refractory cement, any other suitable refractory material, or partially by a suitable adhesive. The housing 25 of the sensing elements (21, 22) is substantially cylindrical in shape and sized to fit snugly within a bore 26 of the metal body 7. The central longitudinal bore 26 penetrates the body 7 and extends from the immersion end 27 to the rear end 28, and can be drilled, for example, in a cast solid metal body. The mass of the complete assembly is 8 g / cm³. 3 Its density is approximately 180g, of which 150g is related to the metal body.

[0112] During the measurement sequence, the measurement probe is placed over the molten metal bath. Once positioned, the sensor unit can be released and separated from the carrier by appropriate means. The sensor unit is then accelerated towards the molten metal, either by gravity alone or by an additional external acceleration mechanism.

[0113] Figure 3 shows an exemplary measurement setup in which the measurement probe 1 of the present invention may be advantageously used. Accelerators (accelerators, 31) are incorporated into the sidewall of a metallurgical vessel 30, such as an electric arc furnace (EAF). An EAF used in steelmaking typically includes a vessel 32 that holds a molten metal bath 33 and a removable lid 35 into which one or more electrodes 36 can enter the furnace. A slag layer 34 covers the molten metal 33. The electrodes 36 used to heat the metal are positioned above the vessel 32. Typically, the inside of the metallurgical vessel 30 is heated to a temperature of about 600 to 2000°C or higher during processing.

[0114] When performing measurements with the equipment shown in Figure 3, the first step is to mount the measurement probe 1 on the accelerator 31 (configuration shown). The extension cable 39 connects the sensor unit of the measurement probe 1 to a processing unit 40, which may be located away from the container 30.

[0115] Inside the accelerator 31, the sensor unit is separated from the carrier component of the probe 1. This separation can be achieved, for example, by a suitable device inside the accelerator 31, such as a shoulder or barrel-shaped cone, against which the retaining means of the probe 1 is pressed, releasing the sensor unit. It should be emphasized that no connection between the sensor unit and the signal lines or suitable connectors is disconnected and that all connections remain in place at least until the measurement sequence is complete.

[0116] Subsequently, the sensor unit is accelerated, for example, by compressed air and ejected from the accelerator 31 into the interior of the container 30 toward the molten metal bath 33 with high initial velocity and momentum. The sensor unit flies in a straight line toward the molten metal 33 and penetrates the surface 38. The signal lines connected to the sensor unit are drawn out from the carrier element behind the sensor unit and are also selected to survive in the harsh environment inside the container for a sufficiently long time to ensure that measurements can be taken.

[0117] Due to the individual wires, associated minimized size and mass, and optimized dimensional ratio, the measurement probe according to the present invention is particularly suitable for measurement sequences involving active acceleration.

[0118] When the sensor unit is immersed below the surface of the molten metal bath, the desired parameters can be measured, and each signal is transmitted to the appropriate processing unit 40. After recording the necessary data, the accelerator 31 can be removed from the probe 1 by releasing, for example, the elements of the probe 1 that have not been injected into the molten metal into the molten metal bath 33.

[0119] Figure 4 shows a sensor assembly 50 having a sensor unit 4 including a steering element 51. The steering element 51 supports a first section of a signal line 3 connected to a sensing element in a metal body 6 (connection not shown). The steering element 51 is wire-shaped, and may be, for example, a steel wire, with its first end attached to the metal body 7 of the sensor unit 4. In the illustrated embodiment, the signal line 3 includes three individual wires. The wires are routed along the steering element 51 in a single elongated loop and are partially secured to the steering element 51. The securing means may be, for example, paper tape 52, which burns away easily as soon as the sensor unit 4 enters the molten metal. The sensor assembly 50 includes a cup-shaped protective element 8 having an elongated lateral slit 53. Such an opening accelerates the melting of the protective element 8 in the molten metal. The cap may include a plurality of lateral openings.

[0120] Those skilled in the art will understand that modifications or changes can be made to the above embodiments without departing from the broader inventive concept of the present invention. Therefore, it should be understood that the present invention is not limited to the specific embodiments disclosed, but is intended to encompass all embodiments within the scope of the appended claims. [Explanation of Symbols]

[0121] 1. Measuring probe 2. Career elements 3 signal lines 4 Sensor Units 5 Release mechanism 6 Sensing Elements 7 Metal body 8. Protective cap 9. Winding of signal wires 10 Probe contact elements 21 Oxygen Measurement Cell 22 Thermocouples 23 Bath contact point 24 Electrical Connectors 25 Sensing element housing 26 Bore of the metal body 27 Immersion end of metal body 28 Rear end of the metal body 30 Metallurgical vessels 31 Accelerator 32 Container 33. Molten metal bath 34 Slag Layer 35 Removable lid 36 EAF electrodes 37 Entrance Point 38 Surface of the molten metal bath 39 Extension Cable 40 Processing Unit 50 Sensor Assembly 51 Steering Elements 52 paper tapes 53 Openings of protective elements

Claims

1. A measuring probe for molten metal, A sensor unit adapted to determine at least one parameter of the molten metal, Sensing elements and, A sensor unit including a metal body that at least partially surrounds the sensing element, A signal line including at least two individual wires connected to the sensor unit, Career elements, The signal line is wound within the carrier element, A measuring probe characterized in that the inner diameter of the carrier element is 7 to 20 times the outer diameter of the individual wires.

2. The measuring probe according to claim 1, wherein each of the wires has an outer diameter in the range of 0.2 to 3 mm.

3. The measuring probe according to claim 1, wherein the mass of the sensor unit is in the range of 80 to 500 g.

4. The measurement probe according to claim 1, wherein the sensor unit includes a plurality of sensing elements.

5. The measurement probe according to claim 1, wherein the sensor unit includes a thermocouple and / or an electrochemical cell.

6. The measuring probe according to claim 1, wherein the active region of the sensing element has a diameter of less than 2.5 mm.

7. The measuring probe according to claim 1, wherein the ratio of the diameter of the active region of the sensing element to the diameter of the individual wires is in the range of 1-1 to 1-4.

8. The measuring probe according to claim 1, wherein the response time of at least one sensing element is less than 5 seconds.

9. The measuring probe according to claim 1, wherein the net density of the combination of the sensing element and the metal body is at least 80% of the density of the metal body.

10. The measuring probe according to claim 1, wherein the maximum cross-sectional area of ​​the central void of the metal body is less than 25% of the maximum total cross-sectional area of ​​the metal body.

11. The measuring probe according to claim 1, wherein the density of the signal lines is 50% or less of the net density of the combined sensing element and the metal body.

12. The measurement probe according to claim 1, wherein the sensor unit includes a steering element.

13. A method for measuring at least one parameter of molten metal or slag using the measuring probe described in claim 1.

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