JPH0560622A - Acoustic temperature measuring method and its apparatus - Google Patents

Abstract

PURPOSE:To improve the temperature measuring accuracy by storing a reference reflecting wave and a reflecting wave at the measuring time within a sound wave sensor, and detecting the propagating time based on the stored reflecting waves. CONSTITUTION:One or more sound wave sensors are provided at a side wall 29 of a duct wherein a high temperature fluid runs. The propagating time of sound waves from a sound wave transmitter 30 through the fluid to a sound wave receiver 31 is detected at 12, and the propagating time when the sound waves are reflected in the sensors is detected at 52. The temperature of the fluid is calculated at 27 from the relationship of the propagating time and the distance of a propagating route. Before measuring, a reference reflecting waveform in the sensors when the duct is at ordinary temperatures is stored in a reflecting wave memory 26, and the reflecting waves in the sensors at the measuring time are stored in a detecting wave memory 11. A reaching time corrector 51 consequently adjusts the time, and a temperature operator 27 calculates the propagating time within the duct and converts to the temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic temperature measuring method and apparatus, and more particularly to an acoustic temperature measuring method and apparatus for determining a fluid temperature in a duct in a high temperature atmosphere or a corrosive atmosphere by using sound waves.

[0002]

2. Description of the Related Art A conventional acoustic temperature measuring device (Japanese Patent Application Laid-Open No. HEI 2-
(See Japanese Patent No. 112741) is shown in FIG. This acoustic thermometer includes a horn 32 attached to a side wall 29 of a duct, a waveguide 33, a sound wave transmitter 30, a sound wave receiver 31 (hereinafter, these four are collectively called a sound wave sensor), a controller 4, a waveform. Generator 6, transmission amplifier 7, reception amplifier 10, A / D
It comprises a converter 9, a propagation time detector 12, a temperature calculator 27, and a display 28.

The procedure for measuring temperature is shown below. The controller 4 sends a measurement start signal to the waveform generator 6, and the waveform generator 6
To send a transmission signal from. The transmission signal is amplified by the transmission amplifier 7, converted into a sound wave by the sound wave transmitter 30, and transmitted into the duct via the waveguide and the horn. Then, the sound wave that has propagated in the gas in the duct is received by the sound wave receiver 31,
It is amplified by the reception amplifier 10. The propagation time detector 12 obtains the propagation time of the sound wave using this received signal. However, the propagation time of the sound wave that has reached the receiver includes the time for the sound wave to propagate through the waveguide, so it is corrected by the method described below. Then, the temperature calculator 27 converts the propagation time into temperature, and the result is displayed on the display 28.

The above example uses two sets of acoustic sensors, but only one set can be used, and the same principle can be used by measuring the reflected wave from the wall. Also, either one of the horn and the waveguide may be sufficient, or it may be necessary to provide two at the same time. FIG. 4 shows a method of correcting the propagation time of the waveguide section. An outline of the propagation path is shown in FIG. t _AB is the propagation time of the sound wave from the 14 speakers A to the 15 microphone B, and t _BA is the propagation time of the sound waves from the 16 speakers B to the 17 microphone A. t _dA is the propagation time of the reflected wave in the sound wave sensor A, and t _dB is the propagation time of the reflected wave in the sound wave sensor B. FIG. 4B shows a sound wave signal that reaches the microphone B from the speaker A. The horizontal axis represents the time after the sound wave is emitted from the speaker, and the vertical axis represents the output voltage of the microphone amplifier. The propagation time t _AB is obtained from the arrival wave in the sound wave signal. This propagation time t _AB also includes the time during which the sound wave propagates through the waveguide section.
Therefore, the propagation time of the waveguide section is corrected using the reflected wave in the sound wave sensor. FIG. 4C shows a reflected wave in the sound wave sensor A. The waveform immediately after the sound wave is transmitted is the direct wave 18 that directly reaches the microphone A from the speaker A. About 8 from sound wave transmission
The sound wave that arrived after ms is a reflected wave 19 that is reflected back from the tip of the horn. The propagation time t _dA is obtained from this reflected wave. Similarly, t _BA and t _dB are obtained, and the propagation time t which propagates in the duct is calculated by the following equation.

[0005]

[Equation 1]

Using this propagation time, the fluid temperature T (K) is determined by the following equation.

[0007]

[Equation 2]

Here, L is the propagation distance in the duct, and α is a gas constant determined by the gas composition.

[0009]

In the above prior art, the following problems occur when the distance between the tip of the horn and the microphone is short, or when the connecting portion between the horn and the waveguide has steps or corners. FIG. 5A shows an example in which the distance between the tip of the horn and the microphone is short. The distance L ₁ between the microphone and the tip of the horn is shown in FIG.
Shows a waveform 36 received when is set to 200 mm. As shown in FIG. 5C, since the direct wave 34 and the reflected wave 35 from the tip of the horn overlap this received waveform, the propagation time t _d of the reflected wave from the tip of the horn cannot be obtained.

FIG. 6A shows an example in which a step or a corner is provided at the connecting portion between the horn and the waveguide. FIG. 3B shows the received waveform when the distance L ₂ between the connecting portion 37 and the tip of the horn is 200 mm. As shown in FIG. 7C, the reflected wave 19 is a superposed wave of the reflected wave 38 generated by the step or corner of the connecting portion and the reflected wave 35 of the tip of the horn. Therefore, t _d of the reflected wave 35 from the tip of the horn cannot be accurately obtained.

The following is the result of trial calculation of the magnitude of the error when the propagation time cannot be corrected as described above. When the temperature in the duct is 1200 ° C., the propagation distance in the duct is 2 m, and the average temperature of the waveguide is 200 ° C., the propagation time of L ₁ and L ₂ = 200 mm cannot be corrected as described above,
The measurement temperature is 885 ° C, which is 315 ° C lower.

An object of the present invention is to detect a reflected wave from the horn tip from the overlapped waveform when the reflected wave from the horn tip overlaps with a direct wave or a reflected wave of other portions, and uses this to detect an accurate wave. An object of the present invention is to provide an acoustic temperature measuring method and device that improve measurement accuracy by obtaining the propagation time t _d .

[0013]

In order to achieve the above object, the first invention of the present application comprises a waveguide and / or a horn, a sound wave transmitter and a receiver on a side wall surrounding a fluid to be measured. One or more sound wave sensors are installed, the total propagation time of the sound waves that reach the receiver from the transmitter via the fluid to be measured is measured, and the propagation time of the sound waves reflected in the sound wave sensor is calculated. In the acoustic temperature measuring method for calculating the temperature of the fluid to be measured from the relationship between the distance of the propagation path and the distance of the propagation path, the reference reflection waveform in the sound wave sensor at the time of reference and the reflection waveform in the sound wave sensor at the time of measurement are stored, The difference between the two waveforms is obtained by matching the initial time of the reference reflection waveform with the initial time of the measurement reflection waveform, thereby obtaining the correct propagation time in the sound wave sensor, and the measured time based on this propagation time and the total propagation time. Calculate fluid temperature On Acoustic temperature measuring method comprising and.

According to a second aspect of the present invention, one or more acoustic wave sensors, which are provided on a side wall surrounding a fluid to be measured and are composed of a waveguide and / or a horn, an acoustic wave transmitter and a receiver, and a transmitter. A total propagation time detector that measures the propagation time of a sound wave that has reached the receiver via a fluid to be measured, a sound wave sensor propagation time detector that finds the propagation time of a sound wave reflected in the sound wave sensor, and these times In the acoustic temperature measuring device including a temperature calculator for calculating the temperature of the fluid to be measured from the relationship between the distance of the propagation path and the distance of the propagation path, a reflection wave memory for storing the reference reflection waveform in the sound wave sensor, and The present invention relates to an acoustic temperature measuring device, which is provided with a reception wave memory for storing reflected waves in the sound wave sensor and a means for detecting a correct propagation time in the sound wave sensor based on the reflected waves in both memories.

[0015]

The operation of the present invention will be described with reference to FIG. The waveform shown here is a waveform in which the reflected wave generated at the connection portion between the horn and the waveguide and the reflected wave from the tip of the horn overlap. Figure 2
In (a), the reflected wave when the temperature inside the horn is 10 ° C is indicated by a solid line,
The reflected wave at 00 ° C. is shown by a broken line. Since the temperature of the waveguide portion at the time of measurement is different between the two, the arrival time of the reflected wave from each connection portion, that is, the arrival time of the reflected wave is deviated.
So that the arrival times of the reflected waves of both are the same,
The arrival time of each reflected wave is detected, and the waveform at 10 ° C. is displayed while being shifted to the left on the time axis according to the arrival time of the waveform at 100 ° C. Since the temperature of the horn portion at the time of measurement is different, the time difference τ between the reflected wave from the connection portion and the reflected wave from the tip of the horn changes, and a difference occurs between the two waveforms. The result of obtaining the difference between the two is shown in FIG. The portion where the difference is generated corresponds to the reflected wave from the tip of the horn at 100 ° C., so the time t _d obtained from the waveform of this difference is obtained.
Is the propagation time of the reflected wave from the tip of the horn at 100 ° C. That is, the waveforms 23 and 22 in FIG.
Is a composite wave composed of the reflected waves 38 and 35, and is a composite wave when the horn internal temperature is 100 ° C. and 10 ° C.

The initial time of the waveform at 10 ° C. is 10
Since it is displayed according to that of the waveform at 0 ° C., when the difference between both waveforms 23 and 22 is obtained, the portion of the waveform 38 is erased, and the difference between the waveform 35 at the temperature of 100 ° C. and 10 ° C. Is generated as 24. Time t obtained from this waveform 24
_This corresponds to the propagation time of the reflected wave from the horn tip when _d is 100 ° C.

That is, the propagation time of the reflected wave from the tip of the horn can be detected by storing the reflected wave at room temperature in the memory in advance and obtaining the difference from the reflected wave at the time of measurement.

[0018]

FIG. 1 shows an embodiment of the present invention. 120 inside
The acoustic wave transmitter 3 is provided on the duct side wall 29 through which the high temperature fluid of 0 ° C. flows.
A pair of sound wave transmitters / receivers consisting of 0 and a sound wave receiver 31 were attached. The processing unit for obtaining the propagation time from the received signal is provided with the reflected wave memory 26, the arrival time corrector 51, and the acoustic wave sensor propagation time detector 52 according to the present invention. Prior to the measurement, when the inside of the duct was at room temperature, a sound wave was emitted from each sound wave transmitter, and the waveform received by the microphone at the same position was recorded in the reflected wave memory 26.

The procedure for measuring temperature is shown below. First, based on the signal from the controller 4, the waveform generator 6 and one of the sound wave transmitters 30 are connected. Next, the controller 4 sends a measurement start signal to the waveform generator 6, and the waveform generator 6 sends a pulse signal. This pulse signal is converted into a sound wave by the speaker 30 of the sound wave transmitter, transmitted through the waveguide, and emitted into the duct. At this time, the measurement start signals are simultaneously A / D
The signal is also transmitted to the converter 9, and the A / D converter starts digitizing the signal from the sound wave receiver and recording it in the reception waveform memory 11. The propagation time detector 12 uses the signal from the receiver on the opposite side of the transmitter that emitted the sound wave to measure the propagation time t _AB.
Ask for. The arrival time corrector 51 first detects the arrival time of the reflected wave using the waveform (the reflected wave in the sound wave sensor) received by the receiver located at the same position as the transmitter that emitted the sound wave. Next, the arrival time corrector 51 compares the arrival time of the reflected wave of the same route at room temperature recorded in advance, and corrects the waveform at normal temperature so that the arrival times of both reflected waves become the same ( After adjusting the time, the difference between the two waveforms is obtained and stored in the received wave memory 11. The propagation time detector 52 in the sound wave sensor obtains the propagation time t _dA from the tip of the horn from the waveform after the above processing.

Next, the relay is switched, and a sound wave is emitted from the other sound wave transmitter to obtain propagation times t _BA and t _dB . Then, the temperature calculator 27 calculates the propagation time t in the duct using the equation (1) and converts it into the temperature using the equation (2). The result is displayed on the display 28. The acoustic thermometer described with reference to FIG. 1 shows a preferred specific example of the present invention, but various modifications can be made without departing from the overall scope of the present invention.

[0021]

According to the present invention, the propagation time of the reflected wave from the horn tip can be detected even if the reflected wave from the horn tip overlaps with the direct wave or the reflected wave from the connection part, so that the accuracy of temperature measurement can be improved. Can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is a diagram illustrating the principle of the present invention.

[Fig. 3]

FIG. 3 and FIG. 4 are explanatory views of a conventional technique.

[FIG. 5]

FIG. 5 and FIG. 6 are explanatory diagrams of problems in the conventional technique.

[Explanation of symbols]

4 ... Controller, 5 ... Relay, 6 ... Waveform generator, 9 ... A / D
Converter, 10 ... Receiving amplifier, 11 ... Receiving wave memory, 1
2 ... Propagation time detector, 13 ... Reference waveform memory, 14 ...
Speaker (for transmission) A, 15 ... Microphone (for reception) B, 1
6 ... Speaker B, 17 ... Microphone A, 18 ... Direct wave, 19
... Reflected wave, 20 ... Arrival wave, 22 ... Reflected wave at 10 ° C, 23
... reflected wave at 100 ° C, 24 ... difference, 26 ... reflected wave memory,
27 ... Temperature calculator, 28 ... Indicator, 29 ... Side wall, 30 ...
Sound wave transmitter, 31 ... Sound wave receiver, 32 ... Horn, 33 ...
Waveguide, 51 ... Arrival time corrector, 52 ... Sound wave sensor internal transit time detector.

Claims (2)

[Claims] 1. A side wall surrounding a fluid to be measured is provided with one or more acoustic wave sensors composed of a waveguide and / or a horn, a transmitter of acoustic waves and a receiver, and the fluid to be measured is sent from the transmitter. The total propagation time of the sound waves that have reached the receiver via is measured, and the propagation time of the sound waves reflected in the sound wave sensor is obtained.
In the acoustic temperature measuring method for calculating the temperature of the fluid to be measured from the relationship between the time and the distance of the propagation path, the reference reflection waveform in the sound wave sensor at the time of reference and the reflection waveform in the sound wave sensor at the time of measurement are calculated. Stored, the initial time of the reference reflection waveform is found to match the initial time of the measurement-time reflection waveform to obtain the difference between the two waveforms, thereby obtaining the correct propagation time in the sound wave sensor,
An acoustic temperature measuring method, wherein the temperature of the fluid to be measured is calculated based on this propagation time and the total propagation time. 2. One or more acoustic wave sensors provided on a side wall surrounding the fluid to be measured, the waveguide and / or the horn, a transmitter of acoustic waves and a receiver, and the fluid to be measured from the transmitter. Total propagation time detector that measures the propagation time of the sound wave that has reached the receiver via the, propagation time detector in the sound wave sensor that obtains the propagation time of the sound wave reflected in the sound wave sensor, and these times and propagation paths In an acoustic temperature measuring device equipped with a temperature calculator for calculating the temperature of a fluid to be measured from the relationship with the distance, the reflected wave memory for storing the reference reflected waveform in the sound wave sensor and the sound wave sensor in the sound wave sensor at the time of measurement. An acoustic temperature measuring device, comprising: a received wave memory for storing the reflected waves of the above, and means for detecting a correct propagation time in the sound wave sensor based on the reflected waves in both memories.