JP2001201406A - Measurement method for refracory furnace temperature and device thereof using optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an effective refractory temperature measurement device by using a Raman scattering type temperature meter, which utilizes an optical fiber as a temperature sensor for constituting a temperature measurement device of a refractory furnace and reducing the distance resolution to be less than ±50 cm. SOLUTION: In a device for measuring temperature distribution in the refractory furnace at each position of fiber 1 extension, by analyzing a time from incidence of laser pulse into the fiber 1 to returning as back scattering light 3 in a state such that the fiber 1 is wound around the furnace wall, wavelength and light intensity, positional accuracy of each measuring point 1A is compensated, based on the emission time of the scattered light at a fixed point by thermally contacting a fixed low-temperature point 1A consisting of a water tube and the like 11 on the way of the fiber 1. The optical fiber, wound around the furnace wall, may be a plural number and the fixed low-temperature point 1A may have a known distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for measuring the temperature of a refractory furnace using an optical fiber temperature sensor, and more particularly to a method and an apparatus for measuring the temperature of an ash melting furnace or a refuse incinerator.

[0002]

2. Description of the Related Art Conventionally, a temperature measuring device using an optical fiber itself as a temperature sensor is known, and is generally called a Raman scattering thermometer. The principle diagram will be described with reference to FIG. 5. When laser pulse light is incident on the optical fiber 1, the light generates scattered light at each passing position of the optical fiber 1. As shown in FIG. 6, the scattered light includes Rayleigh scattered light having the same wavelength as the incident light and Raman scattered light different from the incident light. It is divided into Stokes light. It has been confirmed that the intensity ratio between the Stokes light and the anti-Stokes light has a certain relationship with the temperature of the optical fiber 1 where the scattered light is generated.

On the other hand, a part of the scattered light generated in each part of the optical fiber 1 returns to the incident position again as the back scattered light 3. Therefore, the position where the scattered light is generated can be determined by measuring the time when the light is returned as the backscattered light 3 after the incidence of the incident pulse light. Next, as shown in FIG. 6, by analyzing the wavelength and light intensity of the backscattered light 3 returning to the incident position one after another, each position (measurement distance: maximum 30 km to minimum: usually 1)
m, measurement accuracy: a temperature of up to ± 0.5 ° C.).

[0004]

On the other hand, when measuring the temperature in a refractory of an ash melting furnace or a refuse incinerator, a thermocouple with a sheath is conventionally embedded, but the temperature of each position in the incinerator is measured. Many thermocouples are required to measure the temperature of ash melting furnaces and incinerators to which these sensors are exposed. Depending on the type of gas, the service life was only several weeks in the ash melting furnace and about one year in the refuse incinerator.

Accordingly, by using a Raman scattering thermometer using the optical fiber 1 itself as a temperature sensor in such a refractory furnace such as an incinerator, the sensor is exposed to a corrosive gas since the fiber 1 is made of quartz. Also does not corrode. By winding the optical fiber 1 inside the furnace wall, the temperature distribution of the furnace inner wall at all positions on the fiber 1 can be measured with one fiber 1, so that a large number of thermocouples like a conventional thermocouple are used. It is inferred that a number of sensors are not required and it is very useful in industry.

However, many Raman scattering thermometers have been reported for industrial equipment having relatively long measuring distances, such as transmission lines, tunnels, dams, and oceans, but the measuring distances are 1 m. When used in refractory furnaces such as incinerators within the range, there are few examples because the distance accuracy (position accuracy) is not sufficient. Further, in order to increase the position accuracy, a technique of forming the optical fiber 1 in a loop shape to increase the position accuracy is disclosed, but the distance resolution is ± 50.
cm, and a resolution lower than that cannot be obtained.

According to the present invention, a temperature measuring device for a refractory furnace is constructed by using a Raman scattering thermometer using such an optical fiber itself as a temperature sensor. The invention is to provide an effective invention.

[0008]

According to the present invention, in order to solve the above-mentioned problems, a laser is applied to the optical fiber 1 while the optical fiber 1 is wound along a furnace wall, extended by means of bending or other means. In the method for measuring the refractory furnace temperature distribution at each position where the fiber 1 is extended by analyzing the time from when the pulsed light is incident to when it returns as the backscattered light 3 and the wavelength and the light intensity, the fiber 1 A method for measuring the temperature distribution of a refractory furnace is proposed, wherein the method is brought into thermal contact with a low-temperature fixed point 1A on the way to compensate the positional accuracy of each measurement point 1A based on the emission time of scattered light at the fixed point 1A. When the winding position of the optical fiber 1 is inside the furnace wall along the water pipe 11 for cooling the furnace wall, it is preferable to use, for example, the water pipe 11 as the low-temperature fixed point 1A for bringing the optical fiber 1 into thermal contact. , But is not limited to this. Further, the contact position with the low-temperature fixed point 1A in the middle of the fiber 1 may be a known distance, and as described in claim 4,
Each of the plurality of optical fibers 1 wound multiple times along the furnace wall is brought into thermal contact with a low-temperature fixed point 1A at an intermediate position of a known distance, and based on the average value of the return time of the scattered light of each fiber 1 at the fixed point 1A. Thus, the position accuracy of each measurement point 1A may be compensated.

A fifth aspect of the present invention relates to an apparatus for effectively implementing the first aspect of the present invention, wherein the optical fiber 1 is extended along a furnace wall by winding, surrounding, or other means.
And an incident pulse oscillating means 2 for injecting a laser pulse light into the optical fiber 1, and an analyzing means for analyzing a time until the laser pulse returns as backscattered light 3, and a wavelength and light intensity. In the refractory furnace temperature distribution measuring device at each position where the fiber 1 is extended, a low temperature fixed point 1A which is brought into thermal contact at an intermediate position of the fiber 1 is provided, and each measurement is performed in the analysis means based on the emission time of the scattered light at the fixed point 1A. It is characterized in that a compensating means for compensating the positional accuracy of the point 1A is provided.

According to a sixth aspect of the present invention, the optical fiber 1
Is located inside the furnace wall along the water pipe for cooling the furnace wall, and the low-temperature fixed point 1A at which the optical fiber 1 is brought into thermal contact is the water pipe.

The invention according to claim 7 is that the thermal contact position in the middle of the fiber 1 is a known distance, and the invention according to claim 8 is that the optical fiber 1 is a plurality of optical fibers 1, The plurality of optical fibers 1 are wound multiple times along the furnace wall, and each of the optical fibers 1 is brought into thermal contact with a low-temperature fixed point 1A at an intermediate position of a known distance to obtain a known distance or an average calculated ground value of the thermal contact position. The position compensation is performed as a reference distance.

According to this invention, when the laser pulse light is input to the optical fiber 1, it is backscattered inside, and the position can be obtained from the time until the backscattered light 3 returns to the incident end. When the distance from the incident end to the low-temperature fixed point 1A is a known distance, the difference (N-n) between the known distance N and the calculated distance n obtained from the return time of the backscattered light 3 is divided by the known distance. Is the correction coefficient α: ((N−n) / N), and the calculated distance of each position set based on the return time of the scattered light returning to the incident position one after another is compensated based on the correction coefficient. And the position accuracy can be improved.

Further, the optical fiber 1 is wound in multiple windings, and correction factors α1, α based on the low-temperature fixed point 1A are provided for each fiber 1.
2, α3... Are calculated, and the average value is αv ((α1 + α2 + α
3) / 3) By compensating the positional accuracy, it is possible to improve the positional accuracy with higher accuracy.

Further, the optical fiber 1 is wound in a multiplex manner, and correction factors α1, α based on the low-temperature fixed point 1A are provided for each fiber 1.
2, α3... Are calculated, and the average value is αv ((α1 + α2 + α
3) / 3) By compensating the positional accuracy, it is possible to improve the positional accuracy with higher accuracy. In the case of the multi-turn optical fiber 1, the average value (n1...) Of the calculated distances at the same fixed point 1A position of each fiber 1 can be compensated as the correction coefficient, and the position accuracy can be improved even in this case.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. However, unless otherwise specified, dimensions, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the invention, but are merely illustrative examples. 1 to 3 show a temperature distribution measuring device according to a first embodiment of the present invention.
FIG. 1 is a basic configuration diagram, FIG. 2 is a graph showing a relationship between temperature and one fiber distance showing an operation for compensating positional accuracy, and FIG.
FIG. 3 is a cross-sectional view, a cross-sectional view along line AA, and a cross-sectional view along line BB showing a state where the temperature distribution measuring device is attached to an ash melting furnace.
1 and 2, three optical fibers 1a, 1b,
1c is spirally wound inside the furnace wall 12 along the water pipe 11 for cooling the furnace wall 12, so that the temperature distribution of the entire melting furnace 10 can be obtained. On the incident end side of the three optical fibers 1, an incident pulse oscillating means 2 for injecting laser pulse light into the optical fiber 1, respectively, a time until the laser pulse returns as backscattered light 3, And a temperature analyzer 20 for analyzing the wavelength and the light intensity.
The temperature distribution in the ash melting furnace 10 at each position where the fiber 1 is extended is measured by analyzing the time until returning, and the wavelength and light intensity.

In the above-described embodiment, the low-temperature fixed point 1 which is brought into thermal contact with the fiber 1 at a known distance in the middle of the fiber 1 is provided.
A, and a compensating means 21 for compensating the positional accuracy of each measurement point 1A based on the emission time of the scattered light at the fixed point 1A in the analyzer 20 is provided in the temperature analyzer 20.
When the optical fiber 1 is wound along a water-cooled tube 11, a low-temperature fixed point 1 for bringing the optical fiber 1 into thermal contact is provided.
For example, the water pipe 11 is used as A.

A state in which such a temperature distribution measuring device is attached to an ash melting furnace is specifically shown based on FIG. FIG. 3 shows a cylindrical ash melting furnace 10 in which a cooling water pipe 11 is spirally wound inside a furnace wall 12. And the furnace 10 and the water pipe 1
1. A plurality of optical fibers 1 in which a plurality of optical fibers 1 are spirally multiplex-wound concentrically with the furnace wall in the furnace wall between the two.
Each of them is brought into contact with the water pipe peripheral surface 11 as a low temperature fixed point 1A at an intermediate position of a known distance. In this embodiment, the low-temperature fixed point 1A is provided at three places per one round, specifically, 120 °.
The contact is made at the division position, but is not limited to this. Since it is difficult to bury the fibers 1a, 1b, and 1c directly in the fire-resistant wall, it is preferable to insert and wind the fibers in a stainless steel protection tube 13 of about 2φ.

According to this embodiment, the optical fiber 1
When a laser pulse light having a pulse width of 10 μm or less is input to each of the fibers 1a, 1b, and 1c, the light is backscattered inside the fibers 1a, 1b, and 1c, and the time required for the backscattered light 3 to return to the incident end is determined by the temperature The temperature detection position can be obtained by detecting with an analyzer (detection sensitivity: 50 MHz or more). As shown in FIGS. 1 and 2, as shown in FIGS. Is known, the difference (N−n) between the known distance N and the calculated distance n calculated from the return time of the backscattered light 3 is divided by the known distance to obtain the correction coefficient α: ((N −n) / N), and the position compensation means 21 compensates the calculated distance of each measurement position set based on the return time of the scattered light that returns to the incident position one after another based on the correction coefficient. And the position accuracy can be improved.

Further, as shown in FIG.
a, 1b, and 1c, and each fiber 1a, 1b,
Correction coefficients α1, α2, α based on low-temperature fixed point 1A for each 1c
3 are calculated and the average value αv ((α1 + α2 + α3) / 3)
By compensating for the positional accuracy, the positional accuracy can be further improved.

According to this embodiment, the water-cooled fixed point 1A is provided every several meters instead of the distance resolution of the position accuracy of 1 m, and a set of three turns is used.
m or less.

The optical fiber 1 is a multi-turn optical fiber 1a, 1
In the case of b and 1c, the average value (n1...) of the calculated distances at the same fixed point 1A position of each of the fibers 1a, 1b and 1c can be compensated as the correction coefficient, and the position accuracy can be improved even in this case. FIG. 4 shows an example in which the correction is made by the average value using the apparatus of FIG. 3, and the optical fibers 1a, 1b,
In the case where 1c is a multi-wound optical fiber 1, when the fixed point A is the origin as shown in the figure, b and b 'at the next fixed point B, c and c' at the next fixed point C, and a single-wound portion. Each fixed point 1 in double winding
The calculation position (time) of A is measured differently. In this case, at the fixed point B, the respective average values are {(ab) + (ab ')} / 2, and at the fixed point C, {(ac) + (ac')} / 2. And the temperature distribution is corrected. The same applies to triple winding.

[0022]

As described above, according to the present invention, a temperature measuring device for a refractory furnace is constructed by using a Raman scattering thermometer using the optical fiber 1 itself as a temperature sensor, but the distance resolution is more than ± 50 cm. It is possible to improve the accuracy of the temperature distribution position by shortening the length, and to provide an invention effective as a refractory temperature measuring device.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of a temperature distribution measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a graph showing a temperature / fiber distance relationship showing an operation for position accuracy compensation based on the basic configuration diagram of FIG. 1;

FIG. 3 is a cross-sectional view, an AA line cross-sectional view, and a BB line cross-sectional view showing a state in which the temperature distribution measuring device manufactured based on the basic configuration diagram of FIG. 1 is attached to an ash melting furnace.

FIG. 4 is a graph showing that an average value (n1...) Of calculated distances at the same fixed point position of each fiber is compensated as the correction coefficient using the apparatus of FIG.

FIG. 5 is a principle diagram of a Raman scattering thermometer using an optical fiber itself as a temperature sensor.

FIG. 6 is a measurement example of Raman scattered light.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber 1a, 1b, 1c Multiple winding optical fiber 1A Low temperature fixed point 2 Incident pulse oscillation means 3 Backscattered light 10 Ash melting furnace 11 Water pipe 12 Furnace wall 20 Temperature analyzer 21 Position compensation means

Continued on the front page (72) Inventor Susumu Nishikawa 1-8-1 Koura, Kanazawa-ku, Yokohama-shi Mitsubishi Heavy Industries, Ltd. Inside Yokohama Research Laboratory (72) Michio Abe 1-8-1, Koura, Kanazawa-ku, Yokohama-shi Mitsubishi Heavy Industries, Ltd. 2F056 CL13 VF02 VF11 VF17 2F103 BA37 BA43 BA47 CA07 EB02 EB16 EB35 EC09 ED01 ED06 ED14 FA02 FA15 3K062 AA24 AB01 AB03 AC01 AC03 BA02 CA01 CB03

Claims (8)

[Claims] 1. The time from when a laser pulse light is incident on the optical fiber to when it is returned as backscattered light while the optical fiber is extended along a furnace wall by winding, surrounding, or other means. In the method of measuring the refractory furnace temperature distribution at each position where the fiber is extended by analyzing the wavelength and the light intensity, and in thermal contact with a low-temperature fixed point in the middle of the fiber,
A method for measuring the temperature distribution of a refractory furnace, wherein the position accuracy of each measurement point is compensated based on the emission time of the scattered light at the fixed point. 2. The method according to claim 1, further comprising: bringing a low-temperature fixed point into thermal contact with a known position in the middle of the fiber to compensate for the positional accuracy of each measurement point based on the emission time of the scattered light at the fixed point. Item 4. The method for measuring a temperature distribution of a refractory furnace according to Item 1. 3. The low-temperature fixed point at which the optical fiber is brought into thermal contact when the winding position of the optical fiber is inside the furnace wall along the water tube for cooling the furnace wall is the water tube. 2. The method for measuring the temperature distribution of a refractory furnace according to 1. 4. Each of a plurality of optical fibers wound multiple times along a furnace wall is brought into thermal contact with a low temperature fixed point at an intermediate position thereof.
2. The method according to claim 1, wherein the positional accuracy of each measurement point is compensated based on an average value of the return time of the scattered light of each fiber at the fixed point. 5. An optical fiber extending along a furnace wall by winding, encircling or other means, an incident pulse oscillating means for injecting a laser pulse light into the optical fiber, and the laser pulse as backscattered light. Time until returning, and analysis means for analyzing the wavelength and light intensity, in a refractory furnace temperature distribution measuring device at each position of the fiber extension, comprising a low-temperature fixed point to make thermal contact at an intermediate position of the fiber, A refractory furnace temperature distribution measuring device, comprising a compensating means for compensating for positional accuracy of each measuring point based on an emission time of scattered light at the fixed point in the analyzing means. 6. The optical fiber according to claim 5, wherein a winding position of the optical fiber is in a furnace wall along a water pipe for cooling the furnace wall, and a low-temperature fixed point for bringing the optical fiber into thermal contact is the water pipe. The refractory furnace temperature distribution measuring device described in the above. 7. The refractory furnace temperature distribution measuring apparatus according to claim 5, wherein a thermal contact position in the middle of the fiber is a known distance. 8. The optical fiber is a plurality of optical fibers, and the plurality of optical fibers are wrapped multiple times along a furnace wall, and each of the optical fibers is brought into thermal contact with a low-temperature fixed point at an intermediate position thereof. The refractory furnace temperature distribution measuring apparatus according to claim 4, wherein the position compensation is performed using a known distance or an average calculated ground value of the contact position as a reference distance.