JPH0815040A - Temperature measuring device with optical fiber for high temperature liquid - Google Patents

Abstract

PURPOSE:To prevent the choke of nozzle tip by sending an end of a metal claded optical fiber through a temperature measuring nozzle into high temperature liquid, measuring the liquid temperature with a radiation thermometer at the other end, and supplying gas in the space between the nozzle and the fiber. CONSTITUTION:An optical fiber 11 wound on an optical fiber drum 16 is sent out with a motor 12 driven with a sending controller 14 and its tip is inserted in melt liquid in a furnace 40 so that continuous measurement is made possible by always sending out for the melted loss length. In a temperature measuring nozzle 20, the fiber 11 is inserted from the optical fiber guide 21 side and nozzle choke prevention gas is blown in the space between the nozzle 20 inner wall and outside the fiber 11 through the guide 21. A supply gas controller 33 controls an adjuster 31 so as to fulfill an equation. (Q and M: flowrate and molecular weight of blow gas, Tm and Tl: melt liquid temperature and solidification temperature, Tg and Cp: temperature and specific heat of blow gas) The spectrum light of the melt liquid put in the tip of the fiber 11 is measured with the radiation thermometer 17 at the other end and the temperature signal is output.

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 a temperature of a high temperature liquid, for example, a molten metal temperature in a furnace by using an optical fiber, and more particularly to a temperature measuring apparatus capable of continuous temperature measurement.

[0002]

2. Description of the Related Art Conventionally, as a method of measuring the temperature of molten metal in a furnace, for example, in a converter for decarburizing molten pig iron, which is a steel refining furnace, a sublance method or a thermocouple measurement method by human power is used. There is. In the sublance method,
Temperature measurement is performed from a raw material input port of a furnace (container) by a temperature measuring element attached to the tip of the lance of the lance-shaped movable body.

Therefore, the sublance method has the following disadvantages. First, the temperature measuring device grows in size in proportion to the size of the furnace (container). Further, since the temperature sensing element is a disposable item that can be used only once, it is necessary to replace the temperature sensing element each time the temperature is measured, and the replacement device is additionally required. In addition, since the consumable thermocouple must be replaced every time the temperature is measured, the melting temperature must be measured intermittently during the operation process, and the temperature sensor is frequently used for economical reasons. I can't measure temperature. Therefore, the actual temperature at the processing end point and the target temperature do not always match, causing an energy loss,
Increased production costs, hindered productivity, etc.

Next, as a known document for a method for continuously measuring the temperature in the furnace, there is, for example, one disclosed in Japanese Patent Laid-Open No. 61-91529. The temperature measurement method proposed in this document uses an optical fiber to measure the temperature in the furnace, but since the optical fiber tip is fixed to the tip of the temperature measurement nozzle, Since the temperature is measured through the blowing gas layer, there is a big problem in measurement accuracy. Further, the tip of the optical fiber is exposed to a high temperature for a long time, which causes a problem due to aging.

Further, in Japanese Patent Laid-Open No. 63-203716, the temperature of molten steel is continuously measured so that the temperatures at the end of blowing and at the end point become the target values, and from the rate of change of the temperature rising rate at the end point. In the method for controlling the refining of molten steel to estimate the amount of the component, "the optical fiber is immersed in the molten steel from the bottom, side wall, or upper part of the reactor such as a converter, and the molten steel temperature is continuously measured by a radiation thermometer connected to the optical fiber. However, there is no specific description and the technical content is unknown.

The applicant of the present application filed Japanese Patent Application No. 4-7
In 8736 (Japanese Patent Laid-Open No. 5-78736),
Insert the tip of the metal tube coated optical fiber into a high temperature liquid as a temperature measuring element, and use the measurement principle that the black body radiation condition is satisfied at the tip of this optical fiber, and connect the radiation thermometer to the other end of the optical fiber to measure the temperature. By providing a device for measuring and an optical fiber conveying means for sending out and rewinding the metal tube coated optical fiber, the tip of the metal tube coated optical fiber is inserted into the high temperature liquid for a short time only for the time to measure the temperature of the high temperature liquid. We proposed a temperature measuring device that pulls up the tip immediately after completion, cuts the tip used as this temperature measuring element, and measures with the new tip during the next measurement.

[0007]

However, the temperature measuring device according to Japanese Patent Application No. 4-78736 (Japanese Patent Application Laid-Open No. 5-78736) is an intermittent temperature measuring device, and the temperature is measured at a constant time or every temperature measurement. It was necessary to cut the tip of the optical fiber used as a heating element. Therefore, this device has a problem that continuous measurement cannot be performed for a long time.

The present invention has been made in order to solve such a problem, and it is possible to continuously measure the temperature of a high-temperature liquid, for example, the temperature of molten metal in a furnace using an optical fiber for a long period of time, and to give a response. The purpose of the present invention is to obtain a temperature measuring device for a high-temperature liquid using an optical fiber, which has a high property and a high measurement accuracy.

[0009]

A temperature measuring device for a high temperature liquid using an optical fiber according to the present invention is made of a metal tube and is disposed so as to penetrate a container for holding the high temperature liquid, and one end of the container is in contact with the high temperature liquid. A temperature measuring nozzle, an optical fiber supply means for inserting one end of the metal tube-coated optical fiber previously wound on the drum from the other end of the temperature measuring nozzle and continuously or intermittently feeding the high temperature liquid in the container, Nozzle clogging prevention gas is fed to the warm nozzle, and the gas clogging prevention gas flow rate is set so as to satisfy the following formula (1), and it is connected to the other end of the metal tube coated optical fiber, And a radiation thermometer for measuring the temperature of the high temperature liquid.

[0010]

[Equation 2]

[0011]

In the present invention, the optical fiber supply means is
A radiation thermometer connected to the other end of the metal tube-coated optical fiber is inserted into the high-temperature liquid in the container by inserting one end of the metal tube-coated optical fiber that has been wound in advance into the high-temperature liquid in the container. Measure the temperature of the hot liquid in the container. A nozzle clogging prevention gas is supplied to the gap formed between the inner wall of the temperature measuring nozzle and the outer peripheral portion of the metal tube-covered optical fiber to prevent the tip side of the temperature measuring nozzle from being blocked.

By the way, for example, a ceramic pipe such as alumina or mag carbon (MgO--
If a refractory such as C) with a through hole is used, the temperature measuring nozzle may be broken during use due to thermal stress, thermal shock, etc. In that case, inside the molten metal temperature measuring nozzle. The temperature measurement nozzle is clogged due to the intrusion into the temperature measurement, making temperature measurement impossible. Therefore, in the present invention, a metal tube such as stainless steel is used for this temperature measuring nozzle. Further, in order to prevent nozzle clogging, an inert gas such as argon or nitrogen is supplied to this metal tube, but when the inert gas is supplied, if the amount is too large,
A mushroom (a sponge-like lump in which molten metal is partially solidified) is formed at the tip of the temperature measuring nozzle, and in this case also, the temperature measuring nozzle is clogged and the metal tube-covered optical fiber cannot be inserted. For the production of mushrooms, it is possible to dissolve the mushrooms and supply the optical fiber by blowing oxygen,
When oxygen is blown, melting of the temperature measuring nozzle becomes a problem.
Further, an oxidation reaction of the metal occurs near the outlet of the temperature measuring nozzle, which deteriorates the measurement accuracy. Therefore, the gas flow rate for preventing nozzle clogging should be as small as possible, but if it is too small, the metal tube of the temperature measuring nozzle will be melted, and the metal tube-coated optical fiber will be melted and the temperature cannot be measured. is there.

The inventors of the present invention have conducted various experiments on melting of the tip of the temperature measuring nozzle when supplying an optical fiber using the temperature measuring nozzle made of a metal tube, and have investigated gas temperature, gas type, flow rate and molten metal temperature, When the relationship between the molten metal component and the nozzle diameter satisfies the condition of the above formula (1),
It has been found that the optical fiber can be stably and continuously supplied without melting at the tip of the temperature measuring nozzle. Therefore, by adjusting the gas flow rate within the range shown in the formula (1), it is possible to stably measure the temperature continuously for a long time while preventing the metal tube (temperature measuring nozzle) from melting.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the structure of a temperature measuring device for a high temperature liquid using an optical fiber according to an embodiment of the present invention. In the figure, 10 is an optical fiber supply device, which comprises a metal tube coated optical fiber 11, a motor 12, a roller 13, a feed controller 14, a feed speed detector 15, an optical fiber drum 16 and a radiation thermometer 17. Reference numeral 20 denotes a temperature measuring nozzle for inserting the metal tube coated optical fiber 11 into the furnace, which is also called a temperature measuring tuyere. Reference numeral 21 is an optical fiber guide that is connected to the temperature measuring nozzle 20, and allows the metal tube coated optical fiber 11 to be inserted therethrough.
Nozzle clogging prevention gas is supplied. A nozzle clogging prevention gas supply device 30 is composed of a pressure / flow rate regulator 31, a supply gas controller 33, a supply gas generation unit 34, and a gas pressure detector 35. Reference numeral 40 is a furnace such as a converter or an electric furnace. In the illustrated example, the temperature measuring nozzle 20 is provided on the side wall of the furnace 40, but the temperature measuring nozzle 20 may be provided at the bottom of the furnace 40.

In this embodiment, when measuring the temperature of the high temperature liquid, for example, the temperature of the molten metal in the furnace, the tip of the metal tube coated optical fiber 11 is used together with a nozzle clogging prevention gas (eg nitrogen gas, argon) in the furnace 40. Insert directly into the molten metal or slag inside. At this time, the tip of the metal-tube-coated optical fiber 11 is melted and lost due to high temperature. Therefore, continuous temperature measurement is possible by continuously sending out new optical fiber by the melted amount and continuing the supply.

Here, the structure in which the optical fiber is covered with a metal tube is because the pressure of the nozzle clogging prevention gas is applied to the optical fiber when the optical fiber is fed into the furnace by the optical fiber supply device 10. This is to secure the strength against and protect the internal optical fiber. A stainless steel tube, for example, is used for the metal tube that covers the optical fiber. The melting point of this stainless steel is 1400
Since the temperature is about 1430 ° C, it does not melt immediately when inserted into a high temperature liquid, and protects the optical fiber for several seconds.
Further, in this embodiment, since the optical fiber is also made of silica glass having a softening point of 1600 ° C. or higher, it can maintain its shape without melting for a short time. The outer diameter of the metal tube-coated optical fiber 11 of this embodiment is 1.2.
mm is used.

The temperature measuring nozzle 20 is composed of a single tube made of metal such as stainless steel. This temperature measuring nozzle 20
Has one end that penetrates the side wall of the furnace 40 and is in contact with the high temperature liquid, and the other end that is hermetically coupled to the optical fiber guide 21. The metal tube coated optical fiber 11 is inserted from this optical fiber guide 21 side and inserted into the high temperature liquid. It In addition, the inner wall of the temperature measuring nozzle 20 and the metal tube coated optical fiber 1
A gap is formed between the outer peripheral portion of the nozzle 1 and the outer periphery of the nozzle 1, and the nozzle clogging prevention gas is blown into the gap through the optical fiber guide 21. When the temperature measuring nozzle 20 is composed of a stainless steel (for example, SUS304) single tube nozzle, a nozzle having an inner diameter of 2.0 mm and an outer diameter of about 4.0 mm is used.

The optical fiber guide 21 causes the metal tube-covered optical fiber 11 delivered from the optical fiber supply device 10 and the nozzle blockage prevention gas supplied from the nozzle blockage prevention gas supply device 30 to pass through the temperature measurement hole 41 of the temperature measurement nozzle 20 to the furnace. It has a function of sending out to the molten metal in 40.
One end of the optical fiber guide 21 is hermetically connected to one end of the temperature measuring nozzle 20 that does not come into contact with the high temperature liquid, and the other end can pass the metal tube-coated optical fiber 11, but the nozzle clogging prevention gas is directed to the optical fiber supply device 10 side. In order to prevent leakage, it has a highly airtight structure provided with, for example, a double seal. Further, a pipe from the nozzle clogging prevention gas supply device 30 is connected to the optical fiber guide 21 to supply the above-mentioned gas. Thus, although the optical fiber guide 21 is composed of a member different from the temperature measuring nozzle 20, the function of feeding the optical fiber into the furnace 40 together with the nozzle clogging prevention gas is exactly the same, and in a broad sense, the temperature measuring nozzle is used. It can be regarded as a member forming a part of 20. As described above, the optical fiber guide 21
From the temperature-measuring nozzle 20 which is airtightly connected, the nozzle blockage prevention gas is blown into the molten metal in the furnace 40 together with the delivery of the metal tube-coated optical fiber 11.

The optical fiber supply device 10 has a function of continuously or intermittently feeding the metal tube-coated optical fiber 11 into the furnace 40 via the optical fiber guide 21 and the temperature measuring nozzle 20. Therefore, the feed controller 14
Drives the motor 12 to send out the metal-tube-coated optical fiber 11 which is preliminarily wound in the optical fiber drum 16. In this case, the sending speed of the optical fiber is detected by the sending speed detector 15, and the detected value is used. The control is performed so that the feed rate becomes a predetermined value. The optical fiber supply device 10 also has a function of giving vibration to the optical fiber when stopped. In this embodiment, the continuous feeding speed of the optical fiber is 5 mm / sec, the intermittent feeding speed is 10 mm / sec, the feeding is performed for 10 seconds, and then the operation of stopping for 20 seconds is repeated.

When the optical fiber is sent out, the tip portion of the metal tube-coated optical fiber 11 which is inserted into the furnace 40 together with the nozzle clogging preventing gas is melted and lost with the passage of time. (Only the amount consumed)
Conducted to constantly supply new optical fiber. The continuous supply of this new optical fiber enables continuous temperature measurement.

The feed rate detector 15 can obtain the feed rate from the rotation angle of the sensor roller within a unit time, for example, and this detection signal is used as a feed gas controller in the feed controller 14 and the nozzle clogging prevention gas supply device 30. 33. Then, depending on whether or not the detection value of the feed speed detector 15 is within the normal range, it is possible to determine the difficulty state of the optical fiber delivery.
For example, if the tip of the temperature measuring nozzle 20 becomes clogged, the feed rate will decrease. The feed controller 14 stops driving the motor 12 when the feed speed falls below the normal range,
Prevents equipment failure.

In the present invention, the measurement principle that the absolute temperature can be calculated from the radiation spectrum distribution if the blackbody radiation condition is satisfied is utilized. Therefore, the spectrum light emitted from the molten metal is input from the tip of the metal tube-coated optical fiber 11 inserted in the furnace 40, and this spectrum light propagates in the optical fiber and is input to the radiation thermometer 17. The radiation thermometer 17 includes, for example, a two-color thermometer that determines the temperature by comparing the luminance outputs of two wavelengths and an infrared radiation thermometer that directly determines the temperature from the luminance output of the radiated light. The temperature is calculated in accordance with the measuring method described above, and the calculated temperature signal is output as an electric signal and supplied to, for example, a recording instrument (not shown).

As the gas supplied from the nozzle clogging prevention gas supply device 30 to the optical fiber guide 21, an inert gas (argon in this embodiment) is used. The supply gas controller 33 in the nozzle clogging prevention gas supply device 30 inputs the detection signal of the gas pressure detector 35 and the detection signal of the feed speed detector 15 in the optical fiber supply device 10, and outputs the values of these two detection signals. Accordingly, the pressure / flow rate regulator 31 is supplied. The pressure / flow rate regulator 31 includes a pressure regulator, a flow rate regulator, a control valve, etc., and supplies the input argon to the supply gas generation unit 34 as a pressure and a flow rate according to a control signal. In the supply gas generator 34, argon is generated at a predetermined pressure and is supplied to the optical fiber guide 21 from here.

The gas pressure detector 35 includes the supply gas generator 3
4 detects the gas pressure supplied to the optical fiber guide 21, and supplies this detected value to the supply gas controller 33. This is because when the tip of the temperature measuring nozzle 20 is clogged, the amount of gas supplied is reduced and the detected value of gas pressure rises. Therefore, it is necessary to measure whether the detected value is within the normal range or not. This is because the clogging state of the tip of the warm nozzle 20 can be determined. The supply gas controller 33 determines the clogging state of the tip of the temperature measuring nozzle 20 based on the detection value of the supply gas pressure and the detection value of the optical fiber feeding speed, and adjusts the gas flow rate. In that case, a control signal is sent to the pressure / flow rate regulator 31 so as to satisfy the above expression (1).

FIG. 2 is a diagram showing an example of the temperature measurement results using an optical fiber under the following measurement conditions in a converter. (1) Temperature measurement nozzle, model: Metal single tube nozzle Inner diameter / outer diameter: 2.0 mm / 4.0 mm Material: SUS304 (2) Optical fiber, structure: Stainless steel tube outer diameter: 1.2 mm (3) Gas Blow, type: Argon Temperature: Normal temperature Blow rate: 0.5-5.0 Nm ³ / Hr (4) Optical fiber feed rate: 5 mm / sec (continuous) or 10 mm / sec (intermittent) (5) Molten metal, [ C]: 4.2% to 0.02% Temperature: 1250 to 1650 ° C

In FIG. 2, the waveform that fluctuates up and down is the temperature measured by the optical fiber, and the sublance measurement for confirming the accuracy is performed intermittently. The temperature measured by the thermocouple at this time is shown by a black circle. The difference between the peak value measured by the optical fiber and the value measured by the thermocouple is 4 ° C on average.
Met. Here, the error 4 for the measurement temperature of 1600 ° C
The measurement accuracy of 0.25% was 0.25%, which was a fairly good accuracy. In addition, the feeding speed of the optical fiber is 5 mm continuously.
The same measurement results were obtained in the case of / sec and in the case of intermittent delivery of 10 mm / sec for 10 seconds and then stopping for 20 seconds.

FIG. 3 is a diagram showing a comparison between the thermocouple indicated value (Ts) and the optical fiber thermometer indicated value (Tf), where Ts is shown on the horizontal axis and Tf is shown on the vertical axis. It shows with. The □ marks in FIG. 3 are distributed almost on the straight line of Ts = Tf, indicating that the measurement results are good.

FIG. 4 shows when the above-described embodiment is carried out, that is, when the gas flow rate is maintained in the equation (1) and in other cases.
It is the figure which compared and showed the time which could be measured continuously until it became impossible to supply an optical fiber due to nozzle clogging. From the figure, it can be seen that the present invention enables stable long-term measurement.

[0029]

As described above, according to the present invention, the tip portion of the metal tube-covered optical fiber together with the nozzle clogging prevention gas,
The temperature of the high-temperature liquid is measured continuously or intermittently by inserting it directly into the high-temperature liquid through a temperature-measuring nozzle consisting of a metal tube, and sending out new optical fiber as much as the tip of the optical fiber is melted by the high temperature and continuing the supply. And, since the flow rate of the nozzle clogging prevention gas is adjusted appropriately, it is possible to prevent melting of the tip of the temperature measuring nozzle, and therefore, continuous measurement for a long period of time and quick response, It is possible to measure the temperature of a high temperature liquid with an optical fiber that also has good measurement accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a temperature measuring device for a high temperature liquid using an optical fiber according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a temperature measurement result in the embodiment of FIG.

FIG. 3 is a diagram showing a comparison between a thermocouple command value and an optical fiber thermometer command value in the embodiment of FIG.

FIG. 4 is a diagram showing a nozzle clogging prevention effect according to the embodiment of FIG.

[Explanation of symbols]

 10 Optical Fiber Supply Device 11 Metal Tube Coated Optical Fiber 12 Motor 13 Rotor 14 Feed Controller 15 Feed Speed Detector 16 Optical Fiber Drum 17 Radiation Thermometer 20 Temperature Measuring Nozzle 21 Optical Fiber Guide 30 Nozzle Clogging Prevention Gas Supply Device 31 Pressure / Flow Rate Regulator 33 Supply Gas controller 35 Gas pressure detector 37 Pressure / flow rate regulator 40 Furnace

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichiro Kikuchi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Inventor Yoshimi Komatsu 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Main Steel Pipe Co., Ltd.

Claims (1)

[Claims] 1. A temperature-measuring nozzle, which is made of a metal tube and penetrates through a container that holds a high-temperature liquid, and one end of which is in contact with the high-temperature liquid, and one end of a metal-tube-coated optical fiber that is wound in advance on a drum. An optical fiber supply means for continuously or intermittently feeding into the high temperature liquid in the container by inserting it from the other end of the temperature measuring nozzle, and feeding a nozzle clogging prevention gas to the temperature measuring nozzle,
A gas supply means having a nozzle clogging prevention gas flow rate set to satisfy the following equation: A temperature measuring device for a high-temperature liquid using an optical fiber, comprising: a radiation thermometer connected to the other end of the metal tube-covered optical fiber to measure the temperature of the high-temperature liquid.