JPS6145942A - Measuring method of ultrasonic temperature distribution and waveguide device for method - Google Patents

Abstract

PURPOSE:To measure a spatial temperature distribution by dividing a temperature measured area into (n) areas, coupling (n) kinds of materials which differ in rate of temperature variation in acoustic velocity directly with the respective areas, and arranging them in parallel and measuring the time of ultrasonic wave propagation between both waveguide ends. CONSTITUTION:A troidal core 21 is fed with electricity to generate plasma in a vacuum container 22, that is controlled stably, and its characteristics are analyzed by an experimental device 20. In this device, (n) waveguides W1-Wn having (n) kinds of metal arrayed in a matrix are stuck on the periphery of the coil 21. Ultrasonic waves are transmitted from transmitters X at one-terminal sidces of the respective waveguides W1-Wn and intervals of time up to reception by receivers R are measured by a time difference measuring instrument 10; and time differences are computed by a temperature distributin arithmetic unit 11 to display temperatures of the respective areas. Consequently, the temperature distribution of an area where there is disturbance of an electric or magnetic field is measured accurately.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention utilizes the phenomenon that the speed of sound in a substance changes depending on temperature to detect changes in the speed of ultrasonic waves traveling through a waveguide! FI, relates to an ultrasonic temperature distribution measuring device capable of accurately measuring spatial temperature distribution, and relates to a device suitable for measuring spatial temperature distribution in, for example, blast furnaces, fusion reactors, nuclear reactors, etc. [Background of the Invention] ] Until now, the method of measuring the temperature of a substance from changes in the speed of sound in the substance has been applied to measuring the temperature of liquids, water, etc.

In particular, when measuring the temperature of a chemically active substance that is too low or too high to be contacted by an ultrasonic transmitter or receiver, a waveguide that can withstand contact with the substance is required, as shown in Figure 2. The tube 1 is inserted into the temperature measurement region 5 where the substance is present, an ultrasonic transmitter 3 and a receiver 4 are attached to both outer ends of the tube, and the sound speed of the ultrasonic wave therein is measured using the waveguide 1 as a medium. By doing so, the temperature of the temperature measurement area 5 was determined.

In this case, if the temperature is spatially uniform within the region 5 where the waveguide 1 is arranged, the temperature can be accurately determined. However, when the temperature changes spatially, the sound speed of the ultrasonic wave passing through the waveguide changes at various points in the waveguide, but as a result, the average sound speed changes throughout the waveguide, and therefore , only the spatially integrated average temperature can be determined.

Spatial temperature distribution can be measured by methods such as installing thermocouples distributed in many locations, but this is not only complicated and cumbersome as it requires wiring to multiple locations, but also difficult to measure in areas where there are disturbances in electric or magnetic fields. , I hate being overshadowed by it.

[Purpose of the invention]

The purpose of the present invention is to provide a method and method that enables the measurement of spatial temperature distribution using an ultrasonic waveguide even in high temperature or low temperature regions or chemically active regions without being affected by disturbances of electric or magnetic fields. We are in the process of providing equipment.

[Summary of the Invention] It is well known that the speed of sound in a substance changes depending on temperature. In general, as the temperature of a liquid increases, the speed of sound increases. In the case of water, an increase of 100°C increases approximately 80 mis. In the case of metal, as shown in FIG. 3, the speed of sound tends to decrease as the temperature increases. In any case, the rate of change in the speed of sound with temperature is a unique value for each substance. The present invention is based on the following principle that utilizes this property.

In Figure 1, there is an ultrasonic transmitter X and a receiver R on both ends.
Waveguides w, , w2. w3. Each of w4 is a material M4. of equal length (length t). M2. M3. M4
Consists of serially connected. These waveguides are placed parallel to the temperature measurement area and close to each other. Each partial area A1 of the temperature measurement area corresponding to each length t. A2.
A3. Name it A4. Each waveguide w4. lol...
, w, , w4 is the substance M4. M2. M3. M4 are configured to be different from each other (in other words, they form a matrix arrangement) 0 Temperature change in the speed of sound in each material M1 ' M2 ``3 '' 4 Heavy metals cl, c2 . c3. Let it be c4. Also, partial area A4. A2. A3. The temperature of all A4 sheets is T. When , the ultrasonic wave emitted from one oscillator X passes through the waveguide w,
, w2. w3. Propagates through w4 to each receiver RI
C Time until reception 'It. shall be. Temperature T. Substance M4. M2. M3. Let the sound speed in M4 be V1'(To), V2(To), V, (T
o), V4(To), the following relationship holds true.

t 'o v, (r,) + Yz light ten V3 (To) + v4
(To) ... (1) Now, partial area A1 "2
' A, ' 4 temperatures are respectively T1. T2. T
3. When T4, the ultrasonic propagation time t in the waveguide W is expressed as follows.

+ 6' q 790% + v4 (T4) '' (2) Here, the speed of sound v, ('rj) in the material M at temperature Tj is based on the speed of sound vi (To) at temperature T. It is expressed as the following formula.

V, (Tj) = V, (To) + C, - (T, -TO)
-(3) Therefore, equation (2) can be rewritten as follows.

+□ ...(4) v4(TO)+c4(T4-To) Here, for simplicity, it is expressed as ΔT, =T, -To, and both sides of equation (4) are subtracted from both sides of equation (1) 4. and obtain the following equation.

By the way, since vs (To) > c and ΔTi in general, each term on the right side of equation (5) can be approximated as follows.

Therefore, equation (5) can be approximated as shown below.

When to tI is expressed as Δt, equation (7) can be written as.

Similarly, regarding the waveguide W2, is established, Regarding waveguide W3 is established, Regarding waveguide W4 holds true.

Equation (8) In the minor α9, zc, 7V, ('ro)
2 is called the rate of temperature increase during propagation time and is expressed by Di, the following equations α and α are obtained.

Δt1=D, ΔT1+D2ΔT2+r)3ΔT, +D4
ΔT4...-(c) Δt2=D4ΔT, +D1ΔT
2+D2ΔT5+D, ΔT4...0]Δt 5
” D 5ΔT1+D4ΔT2+D, ΔT3+D2ΔT
4...α◆Δt4=D2ΔT1+D3ΔT2+D
4∆T3+D, ∆T4...(G) When formula (2) and αυ are combined into a matrix, the following formula is obtained.

According to the relationship expressed by Equation 06, the reference temperature T of each partial region A is determined from the propagation time shift Δti measured in each waveguide W using the following equation αη. It is possible to calculate the temperature difference ΔTj from .

As described above, for example, as shown in FIG. 1, four waveguides are used, and the ultrasonic propagation time and reference temperature T of each waveguide are determined. By measuring the difference between that in the equation α′? ) to create four partial areas A4. A2. A3. The temperature of A4 can be uniquely determined. Each material M of each waveguide Wi is arranged only in different lengths, so the temperature of the entire area is the reference temperature T. When determining the reference value of propagation time using K, the propagation time of all waveguides is t. Therefore, temperature calibration can be performed simultaneously for each waveguide.

Although the above explanation has been given by way of example in which the area is divided into four partial areas, the present invention is also generally applicable to the case where the area is divided into a plurality of partial areas. That is, the temperature measurement area of the mackerel is divided into n partial areas A1. A2. ...Divided into An, n is 2
(integer greater than or equal to)) Using n waveguides, each consisting of a series connection of n types of materials having different rates of temperature change in the speed of sound corresponding to these partial regions, any one of the above n partial regions exists in A1. The above n types of substances are arranged so that they are different from each other.
Two waveguides are arranged in parallel and close to each other, and the ultrasonic propagation time t1 of each waveguide and all subregions are set to a known reference temperature ToV.
C when there is t. By measuring the difference Δtt f and solving the n-row matrix according to the formula (1), each partial area A
1. A2. ... Reference temperature T of An. The respective temperature differences Δt1. Δt2. ...Δtnwo can be calculated.

[Embodiments of the invention]

FIG. 4 shows an example in which the temperature distribution of a toroidal coil of a plasma experimental device was measured. The plasma experimental device 20 is a device that applies current to a toroidal coil 21 to generate plasma in a vacuum vessel 22, stably controls it, and experimentally analyzes the characteristics of the plasma. Due to the nature of the device, strong electric fields,
Because magnetic fields are generated and change over time to control plasma, for example, thermocouples, which are widely used for temperature measurements, are affected by electric and magnetic fields and cannot be used for accurate measurements. Therefore, we created four
Four waveguides W1°W2. in which seed metals are arranged. W3.
W4 is pasted around the circumference of the toroidal coil 21, a transmitter X and a receiver R are respectively attached to both ends of the toroidal coil 21, and each of these waveguides W, , W2. A) At one end of W3 and W4, the transmitter X emits an ultrasonic wave, and the time interval until it is received by the receiver R is measured by the time difference measuring device 10. The temperature distribution calculator 11 performs arithmetic processing on the measured time difference indicated by 20η, thereby displaying the temperature of each area.

An example of the arrangement of each waveguide is shown in FIG. Each waveguide W1. W
2. W3. W4 is made of iron 101, aluminum 102, Inconel 103, and stainless steel 104 (the temperature coefficient of the sound velocity during the bending is -0.6 m/s/l, -1.5 m/l I/
℃.

-1,2 m/s/℃, -0,4 m/s/'C) are connected in series, and each of these four metal rods has the same length. , partial areas A1., which are divided into four in the circumferential direction of the plasma experimental apparatus 20. A2. A3. Measure the temperature of A4. As shown in the figure, each of these partial areas A+, A2 + 15
+ The four types of metal rods of each waveguide in A4 are arranged so as to be of different types.

The circuit configuration of the time difference measuring device 10 shown in FIG. 4 is shown in FIG.

The transmitter 200 sends a message at fixed time intervals. output the signal and the outgoing trigger that preceded it. The outgoing trigger is
It is counted sequentially by a counter 202, and in the case of FIG. 6, it is counted in quartal notation. Therefore, the quaternary count value of the counter 202 is used as a value representing the transmission order. multiplexer 2
01.degree. 201' are respectively switched according to the above-mentioned transmission order. The multiplexer 201 selects one of the four oscillators X and supplies it with an oscillation pulse;
Ultrasonic waves are transmitted from the transmitter into the waveguide. Similarly, the multiplexer 201' selects one of the four receivers R and inputs the received pulse to the time measuring device 203. Multiplexers 201, 201 illustrated in FIG.
'The switching state of the four waveguides W1 + W2
This corresponds to measuring the ultrasonic propagation time in the first waveguide among r W3+W4. A time measuring device 203 measures the time from the sending pulse output time to the receiving pulse input time, and the subtractor 203 uses the result as the receiving time.
Enter 05. On the other hand, in the reference time memory 204, each waveguide is stored in all partial areas A1. A2. A.

Uniform known reference temperature T at A4. The ultrasonic reception time (reference time) when 'C is present is memorized.

A subtracter 205 outputs a time difference obtained by subtracting the reference time from the reception time. As described above, the time difference measuring device 10 outputs the transmission order indicating the number of each waveguide and the time difference indicating the change in the ultrasonic propagation time of the waveguide.

FIG. 7 is a diagram showing the configuration of the temperature distribution calculator 11 of FIG. 4, which receives the transmission order and time difference and displays the temperature distribution. According to the transmission order, the input time differences are sequentially passed through the selector 206 to the buffer memo IJ.
207. On the other hand, the known reference temperature T. + D2 r
03+04 (temperature increase rate of propagation time) is memory 208
is inputted to the matrix calculator 209 from . memory 20
8. Using the above data from the buffer memory 207,
According to the calculation shown in 20η, the reference temperature T is determined by the matrix calculator 209. Partial area A4. A2 r 15 r
Each temperature difference ΔT1 of A4. ΔT2. ΔT3. ΔT4 is calculated and the known reference temperature T. For To+ΔT4.
To+ΔT2. To+ΔT3°To+ΔT4 is output to the decoder 210. The decoder 210 converts the input value to display it on the display 211, and converts the input value to the display 211.
Output to 11. As a result, partial area AI “2”3
1 The temperature of each A4 is displayed on the display 211.

In this example, in a plasma experimental apparatus where disturbances caused by a magnetic field are large, the temperature distribution of the coil part and outer wall part, where the temperature becomes high due to the current flowing through the magnet part, can be measured with an accuracy of 1° C. or less. From the measured temperature distribution, it is possible to identify areas where the temperature rises abnormally, and it is possible to determine whether there is a current leak or an abnormality in the power supply unit used for the magnet unit.

Although the embodiment using a waveguide using a metal rod has been described above, a waveguide using a liquid can also be used. FIG. 8 shows an example of a structure of a waveguide using a liquid. 30 in the diagram
0 is a metal tube, and the inside of the tube is divided into, for example, three partial regions by a diaphragm 301.

Water is placed in the partial area 302, methyl alcohol is placed in the partial area 303, and glycerin is placed in the partial area 304. This waveguide takes advantage of the fact that the rate of change of the sound velocity in these three types of liquids is different with temperature, and the three waveguides have different placements of the liquid injected in a matrix. Can measure temperature.

If the diaphragm 301 is added and divided into four partial areas and four types of liquids are added thereto, the temperatures at four locations can be measured in the same way.

FIG. 9 shows the structure of a freely bendable waveguide.

The pipe 305 is a flexible pipe made of vinyl chloride, rubber, or the like. The inside of the tube 305 is divided into partial areas by the diaphragm 301, and liquids of the same number of types as the number of partial areas are injected into each partial area, and these liquids have different rates of temperature change in the speed of sound. If the same number of waveguides as the above-mentioned number of partial regions are used in different matrix shapes, the temperature of each partial region can be similarly measured.

When the number of partial areas increases, it may not be possible to prepare the type of liquid to be injected into each partial area.

In such cases, a liquid with a different mixing ratio of organic solvent and water, such as glycerin, is used. A mixed solution of glycerin and water has properties intermediate between those of glycerin and water depending on the mixing ratio. For this reason, if you make a liquid with the mixing ratio changed every 10 times (for example, every 10 times, 10%,...90%
, 100%, the temperature change rate of X sound velocity is different1
One type of liquid can be secured. Similarly, He, N2.
A waveguide in which a gas such as O□, H2, or a mixture of these gases is injected into a tube in divided regions can also be used.

A flexible waveguide as shown in FIG. 9 can be installed in a complicated path to measure temperature distribution, and can also be inserted into a narrow space to measure temperature.

〔Effect of the invention〕

(1) It is possible to accurately measure the temperature distribution in areas where there is disturbance in the electric field or magnetic field where thermocouples cannot be used.

(2) By using high melting point metal scraps, highly heat resistant substances, or chemical action resistant substances in the waveguide, high temperature regions such as temperature distribution in molten metal or temperature in chemically active substances can be achieved. Distribution can be measured.

(3) By using a flexible waveguide, it can be installed in a complicated path or in a narrow area, and the temperature distribution in a portion like the left can be measured.

(4) Since temperatures at multiple locations are calculated in parallel from multiple pieces of data by matrix calculation, the accuracy of calculating the temperature at each location can be improved. At this time, since the error is the square root of the plurality of waveguides, the measurement error is small even if the accuracy of any one of the waveguides is slightly degraded.

(5) The ends of all the waveguides are located at the same location, and the application of the transmitted ultrasonic waves and the signal extraction of the received ultrasonic waves can be performed at the same location, making the arrangement of the measurement system very simple.

(6) By increasing the number of divisions (number of partial regions) of the temperature measurement region, it is possible to increase the fineness with which the spatial temperature distribution is measured.

Therefore, the present invention can accurately measure the temperature distribution in areas where the electric field and magnetic field fluctuate greatly, such as in glasma experimental devices and nuclear fusion devices, so it can be used to stabilize the temperature of these devices and, in turn, to improve the reliability of the device operation. In addition, since it is possible to measure the temperature distribution in a blast furnace, it can be used in various applications such as identifying areas with insufficient melting that can cause defects in steel manufacturing, etc., and preventing the production of defective steel. Dechiru.

[Brief explanation of drawings]

Fig. 1 shows a waveguide device for explaining the present invention in detail, Fig. 2 shows temperature measurement using a conventional waveguide, and Fig. 3 shows the temperature change rate of sound velocity in metal. Figure shown, 4th
The figure shows the present invention implemented to measure the temperature of the magnet part of a GLAZMA experimental device, FIG. 5 shows the arrangement of the waveguides in FIG. 4, and FIG. 6 shows the configuration of an example of the time difference measuring device. Figure 7 is a diagram showing the configuration of an example of a temperature distribution calculator,
FIG. 8 is a diagram illustrating the structure of a waveguide based on the present invention using a liquid, and FIG. 9 is a diagram illustrating the structure of a flexible waveguide based on the present invention. A1. A2. A, l A4... partial area M1.
M2+ M5 r M4...Different substance w1. w2
．． w, , w4... Waveguide X... Ultrasonic transmitter R... Ultrasonic receiver Figure 1 Figure 2 Figure 3 Figure 5 Garden (°C) Figure 4 No. 51. , :4 Bruises

Claims (1)

[Scope of Claims] 1. The temperature measurement area is divided into n partial areas (n is an integer of 2 or more), and each partial area is formed by serially connecting n types of substances with different rates of temperature change in the speed of sound. Let n waveguides be any one
The two subareas are placed in close proximity and parallel to each other in the temperature measurement area so that different materials are located in each subarea, and the time it takes for the ultrasound to propagate between the two ends of each waveguide is measured. An ultrasonic temperature distribution measuring method characterized by calculating the temperature of each partial region based on the ultrasonic propagation time of a waveguide. 2. N types with different temperature change rates of sound speed (n is an integer of 2 or more)
It consists of n waveguides each made of serially connected materials, and an ultrasonic transmitter and an ultrasonic receiver attached to their ends, respectively, and these n waveguides are close to each other in parallel. What is claimed is: 1. A waveguide device for ultrasonic temperature distribution measurement, characterized in that the waveguides are arranged so that different substances are present at the same position in each waveguide.