JPH11248554A - Acoustic type gaseous body temperature measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acoustic type gaseous body temperature measuring device capable of measuring a gaseous body temperature without lowering measuring accuracy without opening a large hole at all the places to be installed of acoustic sensors. SOLUTION: This acoustic type gaseous body temperature measuring device is provided with a first acoustic sensor provided with a horn 20 whose large diameter end is opened in contact with a gaseous body, a sound wave transmitter 3 connected to the small diameter end of the horn 20 for transmitting sound waves to the horn 20, a waveguide 21 inserted to the horn 20 whose one end is opened at the large diameter end of the horn 20 and a sound wave receiver 30 connected to the other end of the waveguide 21 for receiving the sound waves inside the waveguide 21 and a second acoustic sensor provided with the waveguide 21A arranged by opening one end at a position where the sound waves transmitted from the horn 20 to the gaseous body reach through the gaseous body, the sound wave receiver 30 mounted at the other end of the waveguide 21A for receiving the sound waves inside the waveguide 21A and an auxiliary sound wave transmitter 4 mounted at the same other end of the waveguide 21A for transmitting the sound waves to the waveguide 21A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic gas body temperature measuring apparatus, and more particularly to an acoustic gas body temperature measuring apparatus that measures the speed of sound in a high-temperature gas and determines the temperature of the gas body.

[0002]

2. Description of the Related Art As one method of measuring the temperature of a fluid flowing in a duct, there is a method utilizing the fact that the speed of sound in the fluid changes with the temperature of the fluid. Fluid sound speed C (m
/ S) is represented by the following equation, where α is a constant determined by the gas composition, and T is the gas temperature (K).

[0003]

(Equation 1)

FIG. 3 shows a specific apparatus configuration of this method. In general, when measuring the temperature of a fluid, as shown in FIG. 3, a sound wave transmitter 3 and a sound wave receiver 4 are installed with a fluid to be measured interposed therebetween, and a propagation time t therebetween is measured. At this time, the propagation time t can be expressed by the following equation, where L is the distance between the sound wave transmitter and the sound wave sound receiver. L needs to be measured in advance.

[0005]

(Equation 2)

The gas temperature T can be calculated from the propagation time t. By applying this method and arranging a plurality of acoustic sensors (sensors having both functions of a sound wave transmitter and a receiver) around a duct through which a gas flows, as shown in FIG.
The temperature distribution can be measured using the method of (Computed Tomography) (see Japanese Patent Application Laid-Open No. 63-231682).

When such a gas temperature measuring device using sound waves is applied to a large-scale duct through which a high-temperature gas flows, a configuration as shown in FIG. 5 is obtained.

First, in order to make the sound wave reach from the sound wave receiver attached to one side wall of the large-scale duct to the sound wave receiver attached to the other side wall, a sound wave having a large energy is emitted from the sound wave transmitter. There is a need. For this purpose, it is necessary to attach a trumpet-shaped horn 20 as shown in the figure to the side wall 5 such that the large-diameter end is on the gas body side, and attach the sound wave transmitter 3 to the opposite end.

FIG. 6 shows the effect of the trumpet-shaped horn. It can be seen that a loud sound can be transmitted into the duct by increasing the diameter of the horn.

Further, in order to protect the sound wave transmitter and the sound wave receiver from the high-temperature gas flowing in the duct, it is necessary to mount the sound wave transmitter and the sound wave receiver away from the hole formed in the side wall 5. For this purpose, waveguides 21 and 22 are used. Normally, the heat-resistant temperature of the sound wave transmitter and the sound wave receiver is about 60 ° C., and the temperature of the acoustic sensor section is kept at 50 ° C. or less by using cooling air or the like. Therefore, the horn 20 and the waveguide 2
The inside and outside of the sensors 1 and 22 have a temperature gradient of a high temperature (for example, 1000 ° C.) and a normal temperature on the sensor side.

At this time, the time when the sound wave propagates through the horn and the waveguide is a factor of an error on the thermometer side. For example, when the gas temperature in the duct is 1000 ° C., the propagation distance in the duct is 2 m, the average gas temperature in the waveguide is 100 ° C., and the propagation distance in the waveguide is 1 m, the measured value is as low as 355 ° C. Would.

In order to solve this problem, a method has been devised in which a waveguide for a microphone is inserted inside the horn, and the time of propagation through the horn and the waveguide section is directly measured and corrected. (See JP-A-07-325745) In the case of FIG. 5, the sound wave transmitted from the sound wave
-1, is delivered into the duct through the horn 20-1,
The light propagates through the gas in the duct, travels through the waveguide 21-2, and is received by the sound wave receiver 4-2. From this transmission signal, a propagation time t12 between the sound wave transmitter 3-1 and the sound wave receiver 4-2 is obtained.
Is found. The sound wave transmitted from the sound wave transmitter 3-1 is transmitted from the horn 20-1 into the duct, and at the same time, transmitted through the waveguide 21-1 and received by the sound wave receiver 4-1.
By processing this signal, the propagation time tm1 between the sound wave transmitter 3-1 and the sound wave receiver 4-1 can be measured.

Similarly, if a sound wave is transmitted from the sound wave transmitter 3-2 and received by the sound wave receiver 4-1 and the sound wave receiver 4-2 to measure the propagation times t21 and tm2, the following equation is obtained. Thus, the time t for propagating only in the duct can be obtained.

[0014]

(Equation 3)

[0015]

In the above-mentioned acoustic thermometer, a large-diameter (diameter of 2) is provided at all positions where acoustic sensors are installed.
(About 00 mm). Since the boiler furnace and the bank are made of water walls, it is necessary to bend several water walls in order to make the above holes.
As an example, FIG. 7A shows a state of a water pipe when a hole having a diameter of 200 mm is made in a water wall. For this reason, there is a problem that the cost for installing the sensor is high and the construction period is long. In addition, there is a problem that an acoustic sensor cannot be installed in an existing boiler because the water pipe needs to be bent.

Further, there may be a case where a large hole cannot be formed due to the structure of the measuring point. In addition, if a small-diameter hole is drilled without bending the water pipe, and a waveguide and a sound wave receiver are installed, the time for sound waves to propagate through the waveguide cannot be corrected, and the measurement accuracy decreases. Occurs.

An object of the present invention is to provide a water pipe without bending it.
Further, even when a large hole cannot be formed due to its structure, an acoustic gas temperature measuring device can be provided in which an acoustic sensor can be installed without lowering measurement accuracy, and mounting cost can be significantly reduced. It is in.

[0018]

A first means of the present invention for solving the above-mentioned problem is to measure a propagation time of a sound wave passing through a gas body, and to measure a temperature of the gas body based on the propagation time. In the acoustic gas body temperature measuring device to be calculated, a horn having a large diameter end opened in contact with the gas body, a sound wave transmitter coupled to the small diameter end of the horn and transmitting a sound wave to the horn,
A first waveguide inserted into the horn, one end of which is opened at the large-diameter end of the horn; and a sound wave coupled to the other end of the first waveguide, the sound wave in the first waveguide being transmitted. A first acoustic sensor configured to include a sound wave receiver for receiving, and a sound wave sent from the horn to the gas body is disposed with one end opened at a position where the sound wave reaches via the gas body. A second waveguide, a sound wave receiver mounted on the other end of the second waveguide for receiving sound waves in the second waveguide, and a sound wave receiver mounted on the same other end of the second waveguide And a second acoustic sensor configured to include an auxiliary sound wave transmitter for transmitting sound waves to the second waveguide.

According to a second aspect of the present invention for solving the above-mentioned problems, in the first aspect, the first acoustic sensor is mounted on the other end of the first waveguide. And an auxiliary sound wave transmitter for transmitting a sound wave to the waveguide.

The output sound pressure of the auxiliary sound wave transmitter is desirably set to a value not exceeding 1/20 of the output sound pressure of the sound wave transmitter.

By using a waveguide with an auxiliary sound wave transmitter and a sound wave receiver as an acoustic sensor exclusively for reception, an acoustic sensor which can be installed only by providing a small opening in the wall surrounding the gas body can be obtained. . If you only want to receive the sound inside the duct, it is sufficient if there is an opening area that can receive the sound according to the sensitivity of the receiver, in the case of a commonly used electromagnetic microphone,
The opening surface may have a diameter of 10 mm or more. As an example, FIG. 7B shows a case where a hole having a diameter of 10 mm is formed in the water wall. As shown, there is no need to bend the water pipe, and the sensor can be mounted simply and at low cost. In addition, by installing the auxiliary sound wave transmitter in the waveguide for reception, it is possible to measure an accurate time for the sound wave to pass through the waveguide, so that the measurement accuracy does not decrease.

Furthermore, by attaching an auxiliary sound wave transmitter to a waveguide with a sound wave receiver installed in an acoustic sensor with a horn, the propagation time of the horn can be corrected.

[0023]

FIG. 1 shows an embodiment of the present invention. FIG. 1 shows an acoustic gas body temperature measuring apparatus according to an embodiment of the present invention, which is manufactured to measure a furnace outlet gas temperature of a coal-fired boiler having a furnace width of about 20 m according to an embodiment of the present invention. . The illustrated acoustic gas temperature measuring device includes a furnace side wall 5.
The first acoustic sensor with a horn (acoustic sensor 1) attached to the can, the second acoustic sensor only with the receiver attached to the front and rear walls of the can (acoustic sensor 2), and the output signals of the acoustic sensors 1 and 2 A calculation unit (not shown) for performing a required calculation based on the data and outputting a gas body temperature, a control unit (not shown) for driving the acoustic sensors 1 and 2 and controlling the calculation unit, And a display unit (not shown) for displaying an output.

In a commercial boiler, as a method of examining the combustion state of the furnace and the degree of contamination of the furnace wall, it is necessary to measure the furnace outlet gas temperature (FETG). Generally, when measuring FETG, a suction pyrometer in which a thermocouple is covered with a porcelain tube is used. However, due to lack of durability and difficulty in handling, measurement cannot always be performed. On the other hand, the acoustic temperature measuring device is a non-contact type, and is a measurement method capable of constantly measuring.
However, the furnace side wall is covered with a water wall, and FIG.
It is difficult to make a large number of holes having a large diameter such as 200 mm as shown in FIG.

Therefore, in this embodiment, a first acoustic sensor with a horn (hereinafter referred to as acoustic sensor 1) is installed by making holes with an inner diameter of 200 mm in the left and right side walls of the boiler can. A second acoustic sensor having only a receiver (hereinafter, acoustic sensor 2) was installed at each of three locations.

FIG. 1 shows the structure of the acoustic sensor 1 and the structure of the acoustic sensor 2. The acoustic sensor 1 has a trumpet-shaped horn 20 attached to the opening of the side wall 5 with the large-diameter end facing the gas body.
And a sonic wave transmitter 3 that is connected to the small-diameter end of the horn 20 via a waveguide 22 and sends out a sound wave to the gas body through the waveguide 22 and the horn 20; Open at the large diameter end of horn 20 and horn 2
0, a first waveguide 21 having the other end opened outside, a sound wave receiver 30 arranged to be connected to the other end opening of the waveguide 21 and receiving a sound wave in the waveguide 21, An auxiliary sound wave transmitter 4 connected to a position close to the other end of the waveguide 21 via a branch pipe and transmitting a sound wave to the waveguide 21.

The acoustic sensor 2 is located in front of the can where the sound wave transmitted from the horn 20 and propagated via the gas arrives.
A second waveguide 2 disposed between the water pipes on the water wall surface after the can with one end opened toward the inside of the can and the other end positioned outside the can;
1A and a sound wave receiver 30 arranged to be connected to the other end opening of the second waveguide 21A to receive sound waves in the waveguide 21A.
And an auxiliary sound wave transmitter 4 connected to a position close to the other end of the waveguide 21A via a branch tube and transmitting a sound wave to the waveguide 21A.

The acoustic sensor 2 having only the function of the receiver is
A sound wave receiver 30 and an auxiliary sound wave transmitter 4 are installed at an end outside the can of the second waveguide 21A installed in a 15 mm hole opened between water walls.

The procedure for measuring the gas temperature of the present apparatus will be described below.
First, a sound wave is transmitted from the auxiliary sound wave transmitter 4 of the acoustic sensor 2, the sound is received by the sound wave receiver 30 of the acoustic sensor 2, and the propagation time t22 is obtained.

Next, a sound wave is transmitted from the auxiliary sound wave transmitter 4 of the acoustic sensor 1, and the sound is transmitted to the sound wave receiver 3 of the acoustic sensor 1.
0 and the propagation time t11 is obtained.

Next, a sound wave is transmitted from the sound wave transmitter 3 of the acoustic sensor 1, the sound is received by the sound wave receiver 30 of the acoustic sensor 1, and its propagation time t11s is obtained.

Here, t22 / 2 is the time when the sound wave is
Is the time required to travel through the waveguide.

T11s-t11 / 2 is the time required for the sound wave to travel through the horn portion (waveguide 22 and horn 20) of the acoustic sensor 1.

Finally, a sound wave is transmitted from the sound wave transmitter 3 of the acoustic sensor 2, the sound is received by the sound wave receiver of the acoustic sensor 2, and a propagation time t12 is obtained. Then, the time required for the sound wave to propagate only inside the furnace can be obtained by the following equation.

[0035]

(Equation 4)

Actually, as shown in FIG. 2, the acoustic gas temperature measuring apparatus of the present embodiment comprises a total of two acoustic sensors 1 with horns, one on each side wall of the can.
And 3 on each of the can front wall and can rear wall, total 6
The hornless acoustic sensor 2 is provided. Therefore, first, after measuring the propagation time of the waveguide portion of each acoustic sensor, a sound wave is transmitted from the acoustic sensor 1 with the horn, and the other seven acoustic sensors simultaneously receive the sound, and determine the propagation time of each path. It will be.

In the prior art, it was necessary to install horns in all acoustic sensors, and for this purpose, it was necessary to make holes of 200 mm in diameter at all eight locations. This required a great deal of labor and expense due to the need to bend the water pipe. However, by adopting the structure of this embodiment, a hole having a diameter of 200 mm was drilled in only two places, and the same measurement path and measurement accuracy as those of the related art could be obtained.

By converting the propagation times of the multiple paths as described above into temperatures, the gas temperature of the entire measurement section can be known, and the average temperature can be accurately grasped. Further, since the gas temperatures of the left, right, front and rear of the can can be known, the imbalance of combustion or heat transfer can be grasped.

The auxiliary sound wave transmitter is used to prevent the sound wave receiver from being damaged due to excessive sound pressure applied to the sound wave receiver.
The output is set so that the output sound pressure is not more than 1/20 that of the measuring sound wave transmitter.

FIG. 8 shows an example in which an auxiliary sound wave transmitter is attached only to the acoustic sensor 2 without a horn. In this case, the correction formula is as follows.

[0041]

(Equation 5)

However, if the gas temperature in the horn is different from the gas temperature in the waveguide, the measurement accuracy is reduced.

[0043]

According to the present invention, the acoustic sensor can be installed without bending the water pipe and without lowering the measurement accuracy even when a large hole cannot be formed due to the structure, and the mounting cost can be reduced. It can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an arrangement state of the acoustic sensor shown in FIG.

FIG. 3 is a conceptual view showing the principle of acoustic gas body temperature measurement.

FIG. 4 is a perspective view showing an example of a conventional acoustic sensor arrangement.

FIG. 5 is a sectional view showing a conventional technique.

FIG. 6 is a graph showing the effect of a horn.

FIG. 7 is a front view showing a structure of a water wall when a horn and a waveguide are installed.

FIG. 8 is a sectional view showing another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 acoustic sensor with horn 2 acoustic sensor without horn 3,3-1,3-2 sound wave transmitter 4 auxiliary sound wave transmitter 4-1,4-2 sound wave receiver 5,5 'side wall 18 opening for sound sensor Reference Signs List 19 duct 20 horn 21-1, 21-2 waveguide 21, 21A waveguide 22, 22, 22-1, 22-2 waveguide 30 sound wave receiver 20

Claims (3)

[Claims] 1. An acoustic gas temperature measuring device for measuring a propagation time of a sound wave passing through a gas body and calculating a temperature of the gas body based on the propagation time. A horn coupled to a small-diameter end of the horn and transmitting a sound wave to the horn; a first horn inserted into the horn and having one end opened at the large-diameter end of the horn;
A first acoustic sensor comprising: a waveguide, and a sound wave receiver coupled to the other end of the first waveguide to receive a sound wave in the first waveguide; and A second waveguide having one end opened at a position where a sound wave transmitted from the horn to the gas body reaches via the gas body, and mounted on the other end of the second waveguide; A sound wave receiver for receiving sound waves in the second waveguide, and an auxiliary sound wave transmitter mounted on the other end of the second waveguide and transmitting sound waves to the second waveguide. And a second acoustic sensor configured to include the acoustic gas body temperature measuring device. 2. The acoustic gas temperature measuring device according to claim 1, wherein the first acoustic sensor is attached to the other end of the first waveguide, and applies a sound wave to the first waveguide. An acoustic gas body temperature measuring device comprising an auxiliary sound wave transmitter for sending out. 3. The acoustic gas temperature measuring device according to claim 1, wherein the output sound pressure of the auxiliary sound wave transmitter is set to a value not exceeding 1/20 of the output sound pressure of the sound wave transmitter. An acoustic gas body temperature measuring device, comprising: