JPH07243912A - Molten metal temperature measuring device - Google Patents

Abstract

PURPOSE:To provide a device for continuously measuring the temperature of the jet of a molten metal such as molten pig iron and improving the environment and safety of the measuring work. CONSTITUTION:This molten metal temperature measuring device is provided with a radiation thermometer 10, an optical fiber 20 connected to the radiation thermometer 10 and covered with a metal tube, a delivering mechanism 30 delivering the optical fiber 20 at a prescribed speed, a guide section 40 guiding the delivered optical fiber and delivering it into a molten metal 1, a driving device 50 fitted to the guide section 40 and moving the tip section 41 of the guide section 40 to a prescribed position, and a drive control device 80 controlling the driving device 50. When the drive control device 80 receives the signal reporting the approach of another object to the measurement position of the molten metal temperature, it controls the driving device 50 to retreat the guide section 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the temperature of molten metal such as hot metal in a blast furnace.

[0002]

2. Description of the Related Art In blast furnace operation, iron ore, coke, and other limestone auxiliary materials are charged into the furnace, and hot air is blown from the bottom of the furnace to burn the coke, and the heat and reducing gas generated generate iron ore. Is reduced to obtain hot metal. This hot metal is taken out together with the slag from the tap hole provided at the bottom of the furnace, and this operation is usually called tap metal. As the coke burns, the filling in the furnace drops, so raw materials are charged from the top of the furnace to maintain an appropriate filling level.

In blast furnace operation, it is important to carry out steady operation while maintaining various balances such as mass balance and heat balance. In particular, the heat level in the furnace of the blast furnace reflects the situation in the furnace such as the reaction situation in the furnace and affects the consumption of coke and the like. Therefore, accurately grasping the heat level of the blast furnace is very important from the viewpoint of early detection of changes in the furnace conditions and reduction of raw material costs.

Since the heat level of the blast furnace remarkably appears in the temperature of the hot metal produced, it is desired to accurately measure the hot metal temperature. For measuring the hot metal temperature in the blast furnace, there are the following devices and methods as conventional techniques.

(1) Immersion type thermocouple: The hot metal discharged from the tap hole enters the slag removing device called skinma through the hot metal gutter,
Float the slag over the hot metal and remove. The temperature of the hot metal accumulated in this skinma is measured with a disposable immersion thermocouple. (2) Thermocouple with protective tube: The temperature of the hot metal accumulated in the skinma is measured with a thermocouple set in a protective tube made of refractory as in the above.

(3) Radiation thermometer with protective tube: JP-A-4-3
According to the technique disclosed in Japanese Patent No. 48236, a protection tube made of a refractory material having a small hole at its tip is immersed in a molten metal while purging the inside with an inert gas. For the temperature measurement, the radiation temperature of the hot metal seen in the small holes is measured with a radiation thermometer.
In this way, the temperature inside the molten metal is measured
This is because the surface layer of the molten metal has a temperature different from that of the inside of the molten metal due to the variation of the emissivity due to the heat-dissipating foreign matter to the atmosphere and the unevenness of the surface oxidation state.

(4) Optical fiber thermometer: JP-A-4-32
According to the technology described in Japanese Patent No. 9323, a radiation thermometer in which an optical fiber having a durability higher than that of a thermocouple is immersed in a high-temperature melt such as hot metal and the light entering the optical fiber is attached to the other end. To measure.

[0008]

All of the prior arts are devices for measuring the temperature of hot metal such as skinma where hot metal is accumulated. However, hot metal in skinma is
It takes dozens of minutes after starting hot metal tapping until the temperature stabilizes. This is because a large amount of heat is taken from the hot metal until the hot metal gutter and skinma reach a steady state. Therefore,
In any of the conventional techniques, there is a problem that the hot metal temperature during this period becomes considerably low.

To solve this, the temperature of the hot metal spouting from the tap hole may be measured. However, the amount of hot metal ejected from the tap hole is 5 to 10 T / min, and the flow velocity is about 7 to 14 m / sec. When the conventional technique is applied to the temperature measurement of the hot metal ejected at such a high speed, there are the following problems.

(1) Immersion type thermocouple: In this technique, the hot junction of the thermocouple is immersed in the hot metal for a short time (several seconds).
It is impossible to measure the temperature continuously because it melts. Also, when the temperature is measured intermittently, it is necessary to replace the thermocouple each time, and workability is poor.

(2) Thermocouple with protective tube: This technique allows continuous temperature measurement while the protective tube is immersed in the hot metal, but the durability of the refractory material is a problem and the thermocouple is immersed in the hot metal. Repeatedly causes cracks. In particular, when the protective tube is inserted into a jet stream of molten metal such as hot metal, the protective tube is severely worn and easily broken, and the thermocouple is damaged. If the wall thickness of the protective tube is increased to increase the mechanical strength, a temperature difference occurs between the inside and the outside of the protective tube, making it impossible to measure the temperature of the hot metal.

(3) Radiation thermometer with protective tube: This technology
It is difficult to adjust the gas pressure of the purging gas inside the refractory protection tube. When the gas pressure drops a little, hot metal enters through the small hole at the tip of the protective tube, and when it rises a little, the amount of gas blown out increases and the surface of the hot metal near the small hole cools, and the surface temperature is Will be lower. Inside the jet of molten metal such as hot metal, the flow velocity of the molten metal constantly fluctuates greatly, so the pressure in the small hole at the tip of the protective tube also fluctuates greatly. Therefore, it is difficult to make the pressure of the purge gas in the protective tube follow the pressure fluctuation of the molten metal, and gas blowout and hot metal invasion are unavoidable.

(4) Optical fiber thermometer: This technique is a technique for inserting an optical fiber into a hot metal that moves slowly, and cannot be applied to a jet of molten metal such as hot metal.
Even if an optical fiber is inserted into a jet of molten metal such as hot metal, it is ejected and cannot be inserted. Therefore,
If a silica glass rod having a diameter larger than that of the optical fiber is used, the rod can be inserted into the jet stream, but this time the problem arises that it breaks due to the dynamic pressure of the jet stream.

As described above, according to the prior art, it is difficult to insert a temperature sensor into a jet of molten metal that is jetted at a high speed and in large amounts, such as hot metal, and it is necessary to measure the temperature inside the jet of molten metal. I can't. In addition, harmful gases, fumes, and the like are often attached to the periphery of the molten metal, and temperature measurement in the vicinity is a problem in terms of working environment and safety in addition to high heat environment. The present invention provides an apparatus for continuously measuring the temperature of a jet stream of molten metal such as hot metal and improving the environment and safety of measurement work.

[0015]

A first invention is a radiation thermometer, an optical fiber connected to the radiation thermometer and covered with a metal tube, and a feeding mechanism for feeding the optical fiber at a predetermined speed. A molten metal temperature measuring device comprising a guide part for guiding the sent out optical fiber and sending it into the molten metal, and a drive device attached to the guide part and moving a tip end part of the guide part to a predetermined position.

A second invention further comprises a drive control device for controlling the drive device, and the drive control device receives the signal indicating the approach of another object to the measurement position of the molten metal temperature. The molten metal temperature measuring device is characterized in that the driving device is controlled to retract the guide portion.

[0017]

The radiation thermometer used in the ordinary optical fiber thermometer is used to measure the temperature from the distribution of the energy and wavelength of the light transmitted by the optical fiber. The optical fiber used in the present invention is coated with a metal tube and is sent out at a predetermined speed by a sending mechanism.

The optical fiber sent from the sending mechanism is guided to the object to be measured by the guide section. This guide portion is necessary to isolate the radiation thermometer and the delivery mechanism from the temperature measurement target and to protect the radiation metal from heat radiation and fumes. A drive unit is attached to the guide unit, and at the time of temperature measurement, its tip is moved to a position close to the jet of molten metal or the like.

The optical fiber delivered from the tip of the guide has rigidity because it is coated with metal, and is inserted into the molten metal without being ejected from the jet flow. When the optical fiber is inserted in the molten metal to some extent, the metal coating of the optical fiber is melted. When the metal coating melts, the jet of molten metal breaks the strands of the optical fiber (quartz glass or the like), and this portion becomes the end of the optical fiber. The light of thermal radiation from the molten metal around this end enters the optical fiber from this end and is guided to the radiation thermometer for temperature measurement.

The delivery mechanism must be capable of setting the delivery speed to a predetermined value or higher. As a result, the metal tube coating of the optical fiber is not melted outside the molten metal or on the surface layer, and the optical fiber is inserted into the molten metal, so that the temperature inside the molten metal can be measured.

According to the second aspect of the invention, when the drive control means receives the signal informing that another object approaches the temperature measurement position, it outputs a control signal for controlling the drive device. The drive device operates according to the control signal to retract the guide portion from the temperature measurement position. As a result, a collision between the guide portion and another object is prevented.

[0022]

FIG. 1 is a diagram showing an embodiment of the invention. In the figure, 1 is a jet of molten metal, 10 is a radiation thermometer, 20 is an optical fiber coated with a metal tube, 25 is a rotating drum, 30
Is a feed mechanism, 31 is a pinch roll, 32 is a motor,
40 is a guide portion, 41 is a tip portion of the guide portion, 45 is a guide pipe, 47 is a support frame, 50 is a drive device, 60 is a delivery speed control device, 70 is a delivery speed detector, 80 is a drive control device, and 90 is The object detection devices are respectively shown.

The optical fiber coated with a metal tube is wound around the rotary drum 25 like an ordinary optical fiber. The winding start portion of the optical fiber 20 is optically connected to the fixed-side optical fiber by a rotary optical connector.
The temperature can be measured even while the is rotating. The strands of the optical fiber 20 are made of quartz glass and have a diameter of 50 μm. The cladding tube is made of stainless steel and has an outer diameter of 3.2 mm and a wall thickness of 0.2 mm.
Is. Here, the wire diameter is not particularly limited. If the diameter of the cladding tube is too large, it will be difficult for the cladding tube to pass through the inside of the guide pipe 45, and if it is too thin, it will easily buckle, which will hinder the delivery.

The delivery mechanism 30 comprises a pinch roll 31,
The metal tube-coated optical fiber 20 is sandwiched by 31, and the pinch roll is rotated by a motor 32 at a predetermined delivery speed to deliver the metal tube-coated optical fiber 20. The delivery speed is variable in the range of 0 to 600 mm / sec in this embodiment. In this embodiment, the delivery mechanism 30 includes a delivery speed speed control device 60 and a delivery speed detector 7.
0 is provided and the delivery speed is kept constant. The detector 70 and the speed control device 60 may be omitted when an appropriate delivery speed is obtained.

The guide section 40 comprises a guide pipe 45 for passing the optical fiber 20 coated with a metal tube and a support frame 47, and the support frame 47 reinforces the mechanical strength of the guide pipe 45. In this embodiment, the guide pipe 45 is made of stainless steel and has an inner diameter of 5 mm.

A gas for purging flows inside the guide pipe 45 also for cooling. Some kind of seal may be provided at the inlet of the guide pipe to reduce the leakage of the purging gas. However, if completely sealed with an O-ring or the like, the resistance of the optical fiber is sent out. Therefore, the sealing means is determined in consideration of the supply amount of the purging gas. Usually, it is practically sufficient though there is some leakage by narrowing the inner diameter of the guide pipe or the guide pipe having a hole through which the optical fiber 20 coated with a metal tube can pass without resistance.

The tip portion 41 of the guide portion 40 is protected by a coating of refractory material in order to prevent melting of the guide pipe 45 due to splashes of molten metal or the like. As the refractory material, a magnesia-based refractory material was used in this embodiment. Tip part 41 of the guide part
The smaller the inner diameter, the smaller the amount of purge gas required, and the lower the temperature of the molten metal around the inner diameter, which is desirable from the viewpoint of temperature measurement accuracy.

Drive device 5 attached to guide section 40
In this embodiment, 0 is an electric cylinder attached to the support frame 47 of the guide portion 40. As the power of the drive device 50, any other power such as hydraulic pressure and motor may be used as long as it can generate power. In addition, in this embodiment, the entire guide portion 40 tilts around the horizontal axis.
It goes without saying that the vertical and horizontal movements may be appropriately combined depending on the purpose. In the embodiment, another working machine (mud gun) comes to the position where the hot metal temperature is measured to open and close the tap hole, so the upper position is set as the retracted position in order to avoid collision with this working machine.

The drive control device 80 is a microcomputer that controls the drive device 50 of the guide portion 40 to move the tip end portion 41 of the guide portion to near the object to be measured. Further, when a signal for starting work is output from the operation panel of the mud gun or a signal indicating that a work machine such as a mud gun is approaching is output from the object detection device 90, the drive device 50 is moved to retract the guide portion 40. Control.

In this embodiment, when the working machine is approaching, the drive control unit 80 operates in the direction to extend the rod of the electric cylinder. This operation is programmed so that the movement of the electric cylinder becomes small in the initial and final stages of driving in order to avoid sudden start and sudden stop of the guide unit 40. In addition,
In the embodiment, the limit switch is used for detecting the position of the guide portion 40 for the sake of simplicity. However, if an encoder or the like is used, finer control can be realized. The drive control means 8
It goes without saying that 0 can also be used for positioning the insertion position of the optical fiber into the jet of molten metal.

FIG. 2 is a diagram showing the results of measuring the temperature of the hot metal at various feed rates of the optical fiber using the apparatus of the embodiment of FIG. The vertical axis of the figure is the temperature measurement value,
The horizontal axis indicates the measurement time. The measured value was constant when the delivery speed was 400 mm / sec. Therefore, the delivery speed is 4
The measured value at 00 mm / sec is considered to indicate the temperature of the hot metal. If it is slower than that, the measured value will be slightly lower, and at 300 mm / sec, the measured value will be 1 to 2 ° C lower, 1
At 00 mm / sec, the measured value is lower by 3 to 4 ° C.

From this, when the hot metal temperature is obtained with an accuracy of ± 2 ° C. in the analysis of chemical reactions, the delivery speed is 300 m.
It may be m / sec or more. Also, in order to control the normal blast furnace operation, the hot metal temperature is calculated with an accuracy of ± 5 ° C, so 1
It can be seen that it may be set to about 00 mm / sec. The management of the blast furnace operation means, for example, maintaining a good desulfurization process, and preventing a phenomenon or an accident such as a decrease in the temperature in the furnace, which may bring the blast furnace operation into an unsteady state.

FIG. 3 is a diagram showing the results of comparing the temperature measurement results when the apparatus of the present invention is applied to the temperature measurement of hot metal with the prior art. The measurement conditions are the same as in Fig. 2,
The delivery speed was set to 400 mm / sec, and nitrogen gas was supplied as a purge gas at a flow rate of 2 Nm ³ / h into the guide pipe of the guide portion for measurement. The prior art is the above-mentioned (1) immersion thermocouple, and is the result of measuring the temperature of the hot metal accumulated in the skinma using a consumable thermocouple.

In the prior art, in the early stage of tapping, heat is taken by the gutter that guides the hot metal from the taphole to the skinma, so that the hot metal temperature is considerably lower than that at the end of tapping. Looking at the figure,
Even after 25 minutes have passed since the start of tapping, the temperature was 20 ° C. lower and it took 40 minutes to reach 10 ° C. and 1 hour to reach 5 ° C. Using the device of the invention, the temperature of the hot metal is measured in the jet flow, so a constant value is obtained regardless of the time from the start of tapping, indicating that the hot metal temperature can be measured at any time and accurately. ing.

[0035]

According to the present invention, the temperature inside the jet of molten metal can be continuously measured. Since the temperature measurement of the molten metal is automated, the safety of the measurement work is improved and labor can be saved.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the invention.

FIG. 2 is a diagram showing a relationship between an optical fiber feeding speed and a temperature measurement result.

FIG. 3 is a view showing a result of comparison of a hot metal temperature measurement result by an apparatus of the present invention with a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Radiation thermometer 20 Optical fiber coated with a metal tube 30 Sending mechanism 40 Guide part 41 Tip part of guide part 50 Drive device 80 Drive control device

Claims (2)

[Claims] 1. A radiation thermometer, an optical fiber connected to the radiation thermometer and covered with a metal tube, a feeding mechanism for feeding the optical fiber at a predetermined speed, and guiding and melting the fed optical fiber. A molten metal temperature measuring device comprising: a guide part that is fed into the metal; and a drive device that is attached to the guide part and that moves the tip end part of the guide part to a predetermined position. 2. A drive control device for controlling the drive device is provided, and the drive control device controls the drive device when receiving a signal indicating the approach of another object to the position where the molten metal temperature is measured. The molten metal temperature measuring device according to claim 1, wherein the guide portion is retracted.