JPH01291134A - Temperature measuring method for high temperature object - Google Patents

Abstract

PURPOSE:To measure an average temperature of a high temperature object with high accuracy by receiving a reflected ultrasonic wave from plural pieces of slits provided at an interval on an ultrasonic coupling rod and the end face of the coupling rod. CONSTITUTION:In case of measuring an ultrasonic wave propagation time in a molten metal 2 by using ultrasonic coupling rods 3, 4 and ultrasonic transmitting/receiving elements 5, 6, the time required for propagation in the ultrasonic coupling rod is measured in a real time, and by inputting it to a computing element 8, an ultrasonic propagation time in the molten metal 2 is derived. Subsequently, by keeping the length L between end faces 3-1, 4-1 of the coupling rods 3, 4 constant, an average sound velocity in the metal 2 existing between these end faces is derived. As a matter of fact, the inter-rod length L is varied due to a thermal expansion and a corrosion of the coupling rods 3, 4, its correction is required at every measurement. The average sound velocity of the greater part of metals 2 has a temperature coefficient of -0.2--0.6m/S. deg.C. It is different in accordance with a kind of the metal 2 and a temperature area, but since a temperature - sound velocity characteristic of the metal 2 being an object is stored in advance, an average temperature of the metal 2 can be measured continuously from the average sound velocity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the temperature of a high-temperature object, such as a molten metal. The present invention relates to a temperature measurement method suitable for measuring .

[Conventional technology]

It is generally known that real-time management and control of the molten steel temperature in the furnace during blowing operations in a converter furnace is an important requirement for consistently controlling the blowing temperature. In addition, in cases where steel is continuously cast, a tundish is used as an intermediate container between the casting pot and the mold, and the casting condition is to accurately control the temperature of the molten steel in this tundish.
It is also generally known that it is an important requirement that determines the casting operation and the properties of the finished slab.
Therefore, various efforts have been made in the past to strictly perform such temperature control.

That is, conventional methods for measuring molten steel temperature include a spot temperature measurement method using a consumable thermocouple or, for example, the method disclosed in Japanese Patent Application Laid-Open No.
As seen in Japanese Patent No. 11329, there is a continuous temperature measurement method in which a thermocouple is built into a protective tube.

The spot temperature measurement method is a commonly used method, but since a consumable thermocouple is immersed in molten steel, the temperature is measured spot-wise, and the temperature measurement depends on the immersion position. The average temperature in molten steel cannot be measured due to large variations in temperature.

Moreover, a consumable thermocouple is consumed for each measurement, increasing running costs.

In addition, in the continuous temperature measurement method in which a thermocouple is built into a protection tube, the thermocouple protection tube is expensive and easily damaged, resulting in a considerable increase in running costs. There is a time lag in measurement. Also, like consumable thermocouples, the average temperature in molten steel cannot be measured.

For this reason, the inventors of the present application previously filed a patent application filed in 1983-
In No. 229186, we proposed a method for measuring the temperature of a high-temperature object using ultrasonic waves. This is done from an ultrasonic transmitting/receiving element installed via an ultrasonic coupling rod between the high temperature object to be measured.
The temperature is measured based on the propagation time of an ultrasonic wave through the high-temperature object to be measured, the length between the ultrasonic coupling rods of the high-temperature object to be measured, and the predetermined temperature-sound velocity characteristics. . According to this method, the average temperature of a high-temperature object can be measured continuously.

However, there is a problem in that the ultrasonic coupling rods undergo thermal expansion and change in length, and the length between the ultrasonic coupling rods that sandwich the high temperature object to be measured changes, reducing measurement accuracy.

[Problem to be solved by the invention]

The present invention solves this problem and provides a method for measuring the average temperature of a hot object, such as a molten metal, with high accuracy.

[Means and Effects for Solving the Problems] The present invention will be described in detail as an example of temperature measurement of molten metal with reference to the drawings.

In FIG. 1, 1 is a container, and 2 is molten metal, such as molten steel, contained in the container 1. Reference numeral 3.4 denotes an ultrasonic coupling rod, which is provided facing each other with the molten metal 2 in the container 1 interposed therebetween. The ultrasonic coupling rod 3゜4 is a heat-resistant material that has resistance to melting and corrosion against molten steel and other molten metals, slag resistance and spalling resistance in cases where slag is present, and at the same time has ultrasonic propagation performance. Or made of refractory material. A portion of the ultrasonic coupling rods 3, 4 is provided with slits 11, 12, such as drill holes, for example.

The ultrasonic coupling rods 3 and 4 are used to enable ultrasonic transmission and reception between the molten metal 2 and the molten metal 2 using ultrasonic transmitting and receiving elements with low heat resistance, and one end is in contact with the molten metal 2 and the other end is Ultrasonic transmitting and receiving elements 5 and 6 are attached to the .

These ultrasonic transceiver elements 5.6 are electrically connected to the ultrasonic transceiver 7, and are capable of both transmitting and receiving ultrasonic waves. For example, when an ultrasonic wave is transmitted from the ultrasonic transmitting/receiving element 5, a part of the ultrasonic wave is reflected by the end face 3-1 of the ultrasonic coupling rod 3 and is received by the ultrasonic transmitting/receiving element 5, and half of the elapsed time during this period is The time required for propagation in the ultrasonic coupling rod 3 is L2. This propagation time L2 is the ultrasonic transceiver 7
This is determined by the timer installed in the.

■ 12=-1,...(1) A part of the ultrasonic wave propagates through the end face 3-1, the molten metal 2, and the other ultrasonic coupling rod 4, and is received by the ultrasonic transmitting/receiving element 6.
The required propagation time t3 during this period is obtained.

Further, when the ultrasonic wave is transmitted from the ultrasonic transmitting/receiving element 6, it is partially reflected by the one end 4-1 of the ultrasonic coupling rod 4 and received by the ultrasonic transmitting/receiving element 6, and half of the elapsed time L4 during this period is The time required for propagation in the ultrasonic coupling rod 4 is t.

j, =-・t4 ・・・・・・(2)
Therefore, the time t required for ultrasonic propagation in molten metal is t =
t-a-tz-ts...
...(3) can be easily obtained. In other words, when measuring the ultrasonic propagation time in the molten metal 2 using the ultrasonic coupling rod 3. The time required for the ultrasonic waves to propagate through the coupling rod is measured in real time as described above, although it changes with temperature changes, and this is input to the calculator 8.

The computing unit 8 is a computing unit that computes equations (1) to (4), stores temperature-sound velocity characteristics as shown in FIG. 4, and outputs the temperature. The arithmetic unit 8 performs the above (1) (
2) (3) The ultrasonic propagation time in the molten metal can be determined by calculation.

Here, if the length between the end surfaces 3-1.4-1 of the ultrasonic coupling rods 3 and 4 is kept constant, the average sound velocity in the molten metal existing between the end surfaces 3-1.4-1 is V =L/l
・・・・・・It is obtained by (4).

Incidentally, in reality, the length between the ultrasonic coupling rods changes due to thermal expansion and erosion of the ultrasonic coupling rods 3 and 4, so it is necessary to make corrections for each measurement. A portion of the ultrasonic waves transmitted from the ultrasonic transmitting/receiving element 5 is also reflected from each slit 11.12 in the ultrasonic coupling rods 3, 4, and can be received by the ultrasonic transmitting/receiving element 5.6. .

Here, a method of correcting the length L between the ultrasonic coupling rods will be explained. For example, as shown in FIG. 3(a), two slits l
1 and 12 are provided on the ultrasonic coupling rod 4. In Fig. 3, if the required propagation time of the ultrasonic wave from the ultrasonic transmitting/receiving element 6 to the ultrasonic wave 11 is tll, then t-+=t sho
--(5) Similarly, slit 12
Up to f-st, 1, □・-ri,.
(6) Similarly, if tIl is reached up to the end 4-1, then j, = -t.
......(7). One end of the ultrasonic bonding rods 3 and 4 is kept at a high temperature in molten steel, for example, and the other end is kept at approximately room temperature by water cooling or the like, so that a temperature gradient occurs within the ultrasonic bonding rod. For this reason, the distance between the two slits 11 and 12 is set so small that the influence of thermal expansion is equal, and it is sufficiently close to the high-temperature part.
The distance between the end faces 3-1 and 4-1 of 4 is such that there is no difference in ultrasonic propagation velocity due to temperature gradient. Therefore, Figure 3(b)
When the ultrasonic coupling rod 4 undergoes thermal expansion as shown in , the distance 11 a (T
') can be considered constant even after thermal expansion occurs, so 41! a
(T) = βa (T'), and the required propagation time Δt during that time is Δt=t,z ts+, so V (T') = e a (T')/Δt
By finding (8), V (T') can be found as the velocity between the slit 12 and the end face 4-1 based on the previous assumption. Therefore, the distance j between the slit 12 and the end 4-1
2b(r') is Q b(T')□V(T')X (t * t
−2) −−(9). This ff1b (
By determining the difference between T') and A and (T) determined in advance, the tip length change Δβ due to thermal expansion or erosion of the ultrasonic coupling rod 4 can be determined.

Δ e = 1 (r') −1(T)
...0 ports) Therefore, the corrected length L' of the length between the ultrasonic coupling rods is given by the tip length change Δf3 in the ultrasonic coupling rod 3 + the tip length change 24 in the ultrasonic coupling rod 4. L'=L-(Δ23+Δp4)
...(II), and by substituting L' in place of equation (4) again, the accurate sound velocity in the molten metal (2) can be determined.

V=L'/l ・・・・・・
(12) However, the average sound speed of most of the molten metal 2 is -0,
It has a temperature coefficient of 2 to -0.6 m/s/'C. This varies depending on the type and temperature range of the molten metal 2, but since the temperature-sound velocity characteristics of the target molten metal 2 are memorized in advance, the average temperature of the molten metal 2 can be calculated from the balance beam speed in the θ equation. Can be measured continuously.

In addition, in terms of measurement response, extremely fast measurements are possible because only the sound waves are propagated through the substance to be measured.

Note that 9.10 is a water-cooled box for preventing heat from being transmitted to the ultrasonic transmitting/receiving element 5.6 through the ultrasonic coupling rods 3 and 4.

The molten metal 2 whose temperature is measured may be not only molten steel but also other molten metals, and can be similarly employed for molten liquid high temperature slabs and the like.

Further, the ultrasonic coupling rods 3 and 4 can also be installed facing each other in the vertical direction as shown in FIG.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to continuously measure the average temperature of a high-temperature object with high accuracy, and the effect thereof is extremely large from an industrial perspective.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing one embodiment of the present invention, Fig. 2 is an explanatory diagram showing an example of processing of an ultrasonic bonding rod, and Fig. 3 is an explanatory diagram showing an example of processing of an ultrasonic bonding rod. Fig. 3 is an explanatory diagram showing an example of processing of an ultrasonic bonding rod. A diagram for explaining the method, Figure 4 is a diagram showing an example of the temperature-sound velocity characteristic of a high temperature object to be measured, which is stored in advance in the computing unit, and Figure 5 is a diagram showing the arrangement of other ultrasonic coupling rods. .

Claims (1)

[Claims] 1. Ultrasonic waves are emitted from the ultrasonic transmitting and receiving elements installed between the high temperature object to be measured via an ultrasonic coupling rod, and the propagation time in the high temperature object to be measured is measured, and this time and the temperature to be measured are Ultrasonic bonding of a high temperature object In a method of measuring the average temperature of a high temperature object from the length between the rods and a pre-stored temperature-sound velocity characteristic, the ultrasonic bonding rod is coupled with a plurality of slits provided at intervals. Receives the reflected ultrasound from the end face of the rod, calculates the change in the length of the ultrasonic coupling rod from the difference in reception time, corrects the length between the ultrasonic coupling rods of the high temperature object to be measured, and measures the average temperature. A method for measuring the temperature of a high-temperature object, characterized by: