JPH0537232Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is aimed at controlling the temperature distribution inside the furnace where the contents are unloaded during the operation of blast furnaces, shaft furnaces, etc. The present invention relates to a technique for detecting the distribution shape of a softened cohesive zone in a range.

[Prior Art] In order to properly control the furnace conditions of blast furnaces, shaft furnaces, etc., it is important to know and analyze the temperature distribution of the contents in the furnace. Generally, the gas flow in the blast furnace is 1400 ~
Since it is affected by the shape of the softened cohesive zone in the 1500°C range, it is necessary to control the shape of the softened cohesive zone in order to control the gas flow in the blast furnace. Aside from the internal shape, the external shape of the softened cohesive zone can be measured using the 1200°C temperature distribution line.

In Japanese Patent Publication No. 57-48621, a measurement probe with a plurality of temperature sensing parts formed along the length of a hard protective tube is placed radially on the surface layer of the raw material input into the blast furnace, and measurements are taken as the material is unloaded. A method has been proposed in which the temperature is measured at the point reached by the temperature sensing section while the probe is lowered, and the situation inside the furnace is grasped based on the obtained measurement value. That is,
A vertical and horizontal measurement probe is used to measure the temperature distribution inside the blast furnace in two dimensions in the vertical and horizontal directions. A thermocouple is attached as the temperature sensing part to measure the temperature.

There are various types of sheathed thermocouples, such as chromel-alumel (CA) and platinum-platinum rhodium (Pt-PtRh), but they are not reusable, so they are less expensive.
A CA sheath thermocouple is used. However, C.A.
Thermocouples can only accurately measure temperatures up to 1200°C, so the temperature distribution shape inside the blast furnace can only be known up to the outside of the softened cohesive zone.

Figure 6 shows the 1400 to 1500
A measuring element that enables measurement of the internal shape of a softened cohesive zone in the °C range, 1a is a temperature measuring element, 2 is a protective sheath, 3 is a metal wire as a thin metal wire, and 3a is a metal as a connection point. Closed circuit tip of thin wire 3, 3b, 3
C is the open end of the thin metal wire 3, and 4 is a filling of electrically insulating and heat resistant powder.

The metal wire 3 is, for example, a pure nickel wire with a melting temperature of 1453°C, and when it is charged into the furnace with the charge while energizing its two reciprocating wires, it will melt as the load is unloaded, and the temperature will be measured by cutting off the current. It can be detected that the position of the element 1a has reached the melting temperature of the wire metal.

[Problems to be Solved] However, the temperature measuring element described above has some problems. That is, (1) the electrical conductivity of the high-temperature molten slag is quite high, and even if the metal wire 3 is fused, the electrical resistance will not be infinite and cannot be determined with a simple device.

(2) The electrical resistance of the wire during conduction changes significantly as the temperature of the element rises, which, combined with the above (1), makes it difficult to determine whether the wire is blown out.

The purpose of the present invention is to obtain a fusing type temperature measuring element that makes it possible to measure the internal shape of a softened cohesive zone in the range of 1400 to 1500°C by examining the material and structure of the metal wire.

[Means for Solving the Problems] The fusing type temperature measuring element of the present invention has two voltage detection wires made of the same material as the thin metal wires in two places near the connection point of the thin metal wires and sandwiching the connection point. It is characterized in that the two voltage detection wires are drawn out of the protective tube.

[Function] In large furnaces such as blast furnaces, the distance from the temperature measuring end inside the furnace to the measuring device outside the furnace is several tens of meters, so the influence of the resistance of the lead part becomes very large when measuring resistance. On the other hand, the electrical conductivity of molten slag is quite high, especially when it contains _TiO2 .
Because its electrical conductivity is close to that of metal, it cannot simply be treated as an insulator.

This idea was created in view of the above circumstances.
In order to significantly reduce the strand resistance when the temperature sensing element is not fused, compared to the slag bridging resistance that appears when the temperature measuring element is fused, the 4-terminal resistance measurement method can be applied. Voltage detection line 2 in place
A book is attached, and its two voltage detection wires are taken out to the outside of the protection tube.

Further, the voltage detection wire is made of the same material as the thin metal wire so that thermal electromotive force will not occur and interfere with the four-terminal resistance measurement.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings. Note that the reference numerals already mentioned indicate the same parts, and the explanation will be omitted.

FIG. 1 is a longitudinal cross-sectional view of a fusing type temperature measuring element as an example, in which 1 is a fusing type temperature measuring element, 5 is a voltage detection line which is a metal wire made of the same material as the metal wire 3, and 5
Reference numerals a and 5b are attachment points at which the voltage detection line 5 is attached to the metal wire 3, and the positions of 5a and 5b are set close to the closed circuit tip 3a.

Reference numerals 5c and 5d designate lead-out leads on the open-circuit tips 3b and 3c of the voltage detection wire 5 attached to the attachment points 5a and 5b.

FIGS. 2a and 2b are cross-sectional views of the fusing type temperature measuring element 1 shown in FIG. 1, and FIG.
Section A' shows the section B--B' in FIG.

FIG. 3 is a circuit diagram showing a signal detection circuit of the fusing type temperature measuring element 1 of the same embodiment, where 6 is a direct current or alternating current source, and 7 is a voltmeter.

The fusion type temperature measuring element of this embodiment is constructed as described above and operates as follows.

A metal wire 3 and a voltage detection wire 5 are placed inside a metal protective sheath 2 with a heat-resistant and insulating filling 4 made of MgO, Al ₂ O ₃ , etc.
They are packed together and shaped into one piece using wire drawing, etc.

The metal wire 3 is buried in the filling 4 in the protective sheath 2 in a folded manner at its tip, and becomes a closed circuit tip 3a at a fusing detection point.

At 5a and 5b closest to the closed circuit tip 3a, each end of the folded thin metal wire 3 has two terminals, a total of four terminals, and the other end has current terminals 3b and 3c for conducting electricity.
The opening base end 2b is made up of voltage terminals 5c and 5d for blowout detection.

The metal wire 3 is a high melting point metal wire whose melting temperature is known and whose electrical resistance is small in temperature dependence.
For example, for iron-making blast furnaces, chromel wire with a melting temperature of 1427°C or Kanthal wire with a melting temperature of 1510°C is used. The wire diameter may be about 0.3 to 2 mm.

Detection of fusing in the fusing type temperature measuring element 1 is performed by the circuit shown in FIG. This circuit is a blowout detection circuit based on the four-terminal resistance measurement method, and when a constant current is passed through the metal wire 3, a voltage proportional to the resistance between the attachment points 5a and 5b is obtained on the voltage detection wire 5. . Since the current flowing into the voltmeter 7 is small, even if there is some resistance in the voltage detection line 5, the voltage between the intake points 5a and 5b can be detected with almost no error.

In the conventional detection method, between 3b-5a, 3c-5b
The resistance is measured by adding the resistance between
The effect of resistance change in part a was weakened and the fusing detection accuracy was lowered, but in this example, 5a
Since it is possible to extract only the change in the -3a-5b section, by designing the resistance value of the metal wire 3 between 5a-3a-5b to be small, that is, by shortening the distance, contact of the high-temperature slag can be prevented. It is also possible to increase the resistance change ratio when fused and not fused.

In the present invention, the time when this resistance increases is defined as the time of fusing, and it is determined that the atmospheric temperature at the location in the furnace where the fusing type temperature measuring element 1 is located has reached the melting temperature of the metal wire 3.

Figure 4a shows the output voltage of the fusing type temperature measuring element 1 when it is inserted into the furnace. show. In addition, Figure b shows the detection output of the conventional temperature measuring element 1a, which shows that the wire resistance increases as the temperature rises, and at the time of fusing, it is not much different from the slag bridging resistance, making it difficult to determine the fusing point. In this example element 1, since the detected resistance value when not blown is small, the resistance change ratio when fused is large.
A sharp voltage change is observed. In addition, when using chromel wire, the temperature coefficient of electrical resistance of the chromel alloy is small, so when it is not fused (temperature rise period)
There is almost no change in the output, and a highly accurate device that is easy to adjust when designing a blowout determination circuit can be obtained.

When measuring the temperature of the internal charge of a blast furnace using this fusing type temperature measuring element 1, as shown in FIG. type temperature measuring element) is accommodated in the steel pipe 8, and detection holes (for example, 9a to 9d) are provided at predetermined horizontal measurement positions in the length direction of the steel pipe 8, and each detection hole 9a to 9d is
The closed circuit tip 10 of each metal wire 3 (the closed circuit tip 3a of each of the first to fourth fusing type temperature measuring elements is 1
0a to 10d) are exposed to form the measurement probe 11.

The measurement probe 11 shown in FIG. 5 is placed on the upper surface of the mortar-shaped furnace contents at the top of the blast furnace.
For example, use the insertion device shown in Japanese Utility Model Publication No. 56-28678, and place it in a radial position with the tip at the center of the furnace and the base end near the furnace wall refractories. The reactor is placed in a buried state by charging the charge, and descends as the charge is unloaded into the reactor during operation, making it possible to detect in the vertical direction.

In this way, the fusing type temperature measuring element of this example makes it possible to clearly detect the point of fusing of the metal wire, and the melting temperature of the metal wire can be determined from 1400 to 1400.
By accurately knowing the furnace temperature in the 1500℃ range,
It can be used as an effective means of controlling furnace conditions.

Note that the closed circuit tip 3 serves as the connection point of the thin metal wire 3.
A is not limited to a physical connection processing point such as welding, but may be a single thin metal wire folded back into a hairpin shape. Even in that case, it is clear that the function of blowout detection is exactly the same.

In addition, as mentioned above, the material of the wire is preferably one that has little change in electrical resistance due to temperature, which stabilizes the detection output and eliminates load fluctuations in the power supply.
The circuit configuration of the power supply can be simplified.

Further, as described above, the type of metal of the metal wire 3 of the fusing type temperature measuring element of the present invention is changed depending on the temperature range of interest. For example, to understand the softened cohesive zone in a blast furnace, a chromel wire with a melting point of approximately 1427°C or a Kanthal wire with a melting point of approximately 1510°C is suitable. In a reducing atmosphere, the melting point temperature changes due to solid solution of carbon, so as a countermeasure,
It may be used with a sheath or with a radiation injection.

In addition, along with the fusing type temperature measuring element of the present invention, a steel pipe 8
By adding a thermocouple such as a CA thermocouple to the sensor, it is possible to measure temperatures from 0 to 1200°C.

[Effects of the invention] The fusion-type temperature measuring element of the present invention has two voltage detection wires made of the same material as the thin metal wires attached at two locations sandwiching the connection point near the connection point of the thin metal wires. Since the two voltage detection wires are drawn out of the protection tube, (1) The four-terminal method is configured near the tip, so the resistance only at the tip can be accurately measured, and the melting temperature can be sharpened. Can be detected.

(2) Since it is constructed from a pair of metal wires of the same type, no thermal electromotive force is generated between the terminals, making resistance measurement accurate.

Therefore, the internal shape of the softened cohesive zone can be determined from the 1450° C. temperature distribution line, etc., and the overall image of the softened cohesive zone can be accurately grasped. As a result, the shape of the softened cohesive zone can be controlled more easily than before.
The gas flow distribution in the furnace can be controlled accurately.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of a fusing type temperature measuring element of one embodiment, Fig. 2 a and b are cross sectional views of a fusing type temperature measuring element of the same embodiment, and Fig. 3 is a signal detection circuit of the same embodiment. FIG. 4a is a graph showing the output voltage of the fusing type temperature measuring element of the same example, FIG. 4b is a graph showing the detection output of the conventional temperature measuring element, and FIG. 5 is a graph showing the detection output of the conventional temperature measuring element. FIG. 6 is a perspective view of the measuring probe of FIG. 6, and FIG. 6 is a longitudinal sectional view of a conventional measuring element. 1... Fusing type temperature measuring element, 2... Protective sheath, 3
...Metal wire as thin metal wire, 3a... Closed circuit tip as connection point, 3b, 3c... Open circuit tip, 4
...Filling material, 5...Voltage detection wire, 5a, 5b...
Attachment point, 5c, 5d...Voltage detection wire lead, 6...Current source, 7...Voltmeter, 8...Steel pipe, 9a-9d...Detection hole, 10a-10d...
Each closed circuit tip of the first to fourth fusing type temperature measuring elements, 11... measurement probe.

Claims (1)

[Claims for Utility Model Registration] (1) A fusing type measurement method in which two thin metal wires with known melting temperatures are connected at one end and housed in a protective tube, and the temperature is detected by fusing the thin metal wires. In the thermal element, two voltage detection wires made of the same material as the thin metal wire are attached to two places sandwiching the connection point near the mutually connected connection point, and the two voltage detection wires are connected outside the protection tube. A fusing type temperature measuring element characterized by being drawn out. (2) The fusing type temperature measuring element according to claim 1, wherein the material of the thin metal wire and the voltage detection wire is chromel (melting point is approximately 1427°C) or kanthal (melting point is approximately 1510°C). . (3) The fusing type temperature measuring element according to claim 1 or 2, wherein a plurality of the temperature measuring elements are housed in a steel pipe, and each of the connection points is located at a different position in the length direction of the steel pipe.