JP2011122886A - Temperature measuring device and temperature measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature measuring device and a temperature measuring method for simply measuring surface temperature distribution in a duct at low costs and always measuring the surface temperature distribution. <P>SOLUTION: The device is provided with a light receiving part 2, a spectroscopic part 3, and an analysis part 4. The light receiving part 2 is attached on one wall surface of a channel where fluid flows. Light emitted from the other wall surface of the channel and passing through the fluid enters the light receiving part 2. The spectroscopic part 3 disperses the light entered into the light receiving part 2. The analysis part 4 obtains from the light dispersed from the spectroscopic part 3 a measured absorption spectrum which is an absorption spectrum on at least gas, compares a theoretical absorption spectrum at a predetermined temperature of gas with the measured absorption spectrum, and determines a predetermined temperature at which an error between the theoretical absorption spectrum and the measured absorption spectrum is smallest. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a temperature measuring device and a temperature measuring method.

  In general, in an exhaust gas treatment apparatus such as a boiler or a desulfurization apparatus in a chemical plant, in order to grasp the efficiency and improve the performance, the surface temperature distribution in the duct through which the exhaust gas flows is measured in order to improve the efficiency.

As a general method for measuring the surface temperature distribution in a duct of a boiler, a chemical plant or the like, a method of measuring a temperature by inserting a thermocouple and changing the insertion position is known.
In addition, as a method for simultaneously measuring the surface distribution of temperature, a method of measuring the surface temperature distribution by arranging a plurality of thermocouples in a grid shape is also known. Furthermore, a method of measuring temperature distribution using light absorption is also known (for example, see Patent Document 1).

JP-A-8-233668

  However, the method for measuring the surface temperature distribution using a thermocouple has a problem that it takes time to measure the surface temperature distribution. Furthermore, there is a problem that it is not suitable for application to a constant monitor device that constantly measures the surface temperature distribution.

  In the method of simultaneously measuring the surface temperature distribution, there is a problem that the grid of the thermocouple disturbs the state of the exhaust gas flow. Furthermore, there is a problem that it is not suitable for application to a constant monitor device that constantly measures the surface temperature distribution.

  In the measurement method of surface temperature distribution using light absorption, CT (computer tomography) is used, so it is necessary to provide many ports (portions where light is input and output) in the duct to be measured. There was a problem that the measurement of the surface temperature distribution was expensive. Further, the port is provided with a window related to input / output of light, and there is a problem that it is necessary to manage the contamination of the window.

  The present invention has been made in order to solve the above-described problem, and is capable of measuring the surface temperature distribution in the duct inexpensively and easily, and a temperature measuring device capable of always measuring the surface temperature distribution and An object is to provide a temperature measurement method.

In order to achieve the above object, the present invention provides the following means.
The temperature measuring device of the present invention is attached to one wall surface of a flow path through which a fluid flows, a light receiving portion that is emitted from the other wall surface of the flow path and is incident on the light receiving portion. A spectroscopic unit that divides the emitted light, and obtains an actual absorption spectrum that is at least an absorption spectrum of the gas from the light split by the spectroscopic unit, and a theoretical absorption spectrum of the gas at a predetermined temperature, and And an analysis unit that compares the measured absorption spectra and obtains the predetermined temperature at which an error between the theoretical absorption spectrum and the measured absorption spectrum is minimized.

  According to the present invention, since the light emitted from the wall surface and passed through the gas is measured, the temperature of the gas can be measured without using a configuration in which the gas is irradiated with the measurement light. Therefore, the number of components in the temperature measuring device can be reduced, and the temperature can be measured at a low cost. Furthermore, when the temperature is measured, it is only necessary to dispose only the light receiving portion in the flow path, the number of components disposed in the flow path can be reduced, and the temperature can be measured easily.

On the other hand, since the temperature of the gas is measured using light that has passed through the gas emitted from the wall surface, the temperature distribution in the gas flowing through the flow path can be measured inexpensively and easily. That is, since light is emitted from all the wall surfaces surrounding the fluid, the temperature distribution of the gas is measured only by changing the direction of measuring the light in the light receiving unit or changing the light receiving unit for measuring the light. be able to.
Furthermore, since the temperature of the gas is measured using light emitted from the wall surface and passing through the gas, the gas temperature can be constantly measured without obstructing the flow of the gas in the flow path.

  The temperature measurement method of the present invention includes an acquisition step of measuring light emitted from a wall surface of a flow path through which gas flows and passing through the gas, and acquiring an actually measured absorption spectrum that is an absorption spectrum related to the gas; A calculation step of comparing the theoretical absorption spectrum at a predetermined temperature and the measured absorption spectrum to obtain the predetermined temperature at which an error between the theoretical absorption spectrum and the measured absorption spectrum is minimized. It is characterized by that.

  According to the present invention, since the light emitted from the wall surface and passed through the gas is measured, the temperature of the gas can be measured without using a configuration in which the gas is irradiated with the measurement light. Therefore, the number of components used for temperature measurement can be reduced, and temperature measurement can be performed at low cost. Furthermore, when measuring temperature, it is only necessary to arrange components for measuring light in the flow path, the number of components arranged in the flow path can be reduced, and temperature can be measured easily.

  Specifically, the temperature of the gas can be measured by using the temperature dependence in the absorption spectrum, which is the light absorption characteristic of the gas. Therefore, if the absorption spectrum is known in at least one of a plurality of types of gases flowing in the flow path, the temperature of the gas can be obtained. That is, the measured absorption spectrum for the gas is compared with the theoretical absorption spectrum at a plurality of predetermined temperatures, and the predetermined temperature for the theoretical absorption spectrum with the smallest error is the temperature closest to the temperature of the gas. It becomes.

On the other hand, since the temperature of the gas is measured using light that has passed through the gas emitted from the wall surface, the temperature distribution in the gas flowing through the flow path can be measured inexpensively and easily. In other words, since light is emitted from all the wall surfaces surrounding the fluid, the temperature of the gas can be changed only by changing the direction of measuring light in the component that measures light, or changing the component that measures light. Distribution can be measured.
Furthermore, since the temperature of the gas is measured using light emitted from the wall surface and passing through the gas, the gas temperature can be constantly measured without obstructing the flow of the gas in the flow path.

  In the above invention, in the obtaining step, a measured emission spectrum including the measured absorption spectrum is obtained, which is a spectrum related to the intensity of light that has passed through the gas. In the calculating step, light emitted from the wall surface is obtained. The theoretical emission spectrum is calculated based on the approximate spectrum that approximates the emission spectrum relating to the intensity of light and the theoretical absorption spectrum, and the error between the theoretical emission spectrum and the actually measured emission spectrum is minimized. It is desirable to obtain the predetermined temperature.

  According to the present invention, the temperature of the gas can be determined more accurately as compared with the method of measuring the temperature of the gas based on the absorption spectrum. For example, not only by comparing the wavelength at the peak of the absorption spectrum, but also by comparing the magnitude of the absorption spectrum, that is, the rate of decrease in intensity from the emission spectrum related to the intensity of light emitted from the wall surface, etc. The temperature of the gas can be determined.

In the above invention, the absorption spectrum is preferably an absorption spectrum related to water vapor (H ₂ O).
In the above invention, the absorption spectrum is more preferably an absorption spectrum related to water vapor (H ₂ O) in a wavelength range of 750 nm to 850 nm.

  According to the present invention, it is possible to easily and reliably measure the temperature of a gas flowing through a flow path, for example, exhaust gas. That is, since it is normal that water vapor is contained in the exhaust gas, temperature measurement can be performed regardless of the type of the exhaust gas by using the water vapor absorption spectrum. In particular, the absorption spectrum of water vapor in the wavelength range of 750 nm to 850 nm has a small light absorption coefficient and is difficult to saturate the amount of absorption. However, a suitable absorption spectrum can be measured and the temperature can be measured. Furthermore, since the absorption spectrum in the range has temperature dependence, the temperature of the exhaust gas can be measured using this.

  According to the temperature measuring device and the temperature measuring method of the present invention, the light emitted from the wall surface and passed through the gas is measured, and the temperature dependence in the absorption spectrum is utilized to make the temperature distribution in the duct inexpensive and simple. Thus, the temperature distribution can be constantly measured.

It is a block diagram explaining the structure of the temperature measurement apparatus which concerns on one Embodiment of this invention. It is a schematic diagram explaining the structure of the light-receiving part of FIG. It is a schematic diagram explaining a mode that the light emitted from the wall surface of the duct injects into a light-receiving part. It is a graph which shows the actually measured emission spectrum acquired by the analysis part. It is a graph explaining the state which the amount of light absorption was saturated. It is a graph explaining the absorption band of the water vapor | steam which exists in 800 nm to 1000 nm. It is a graph explaining the temperature dependence of the absorption spectrum of water vapor | steam in the 800 nm vicinity. It is a graph explaining the temperature dependence of the absorption spectrum of water vapor | steam in the 800 nm vicinity. It is a graph explaining the temperature dependence of the absorption spectrum of water vapor | steam in the 800 nm vicinity. It is a schematic diagram explaining another Example of the light-receiving part of FIG. It is a schematic diagram explaining another Example of the light-receiving part of FIG.

A temperature measuring apparatus according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram illustrating the configuration of the temperature measurement device according to the present embodiment. FIG. 2 is a schematic diagram illustrating the configuration of the light receiving unit in FIG. 1.
In the present embodiment, the present invention will be described by applying the present invention to a temperature measuring device 1 that measures the temperature distribution of exhaust gas flowing through a duct (flow channel) 10 in a boiler or chemical plant.
As shown in FIGS. 1 and 2, the temperature measuring device 1 mainly includes a light receiving unit 2, a spectroscopic unit 3, and an analysis unit 4.

The light receiving unit 2 is disposed outside the wall surface 11 in the duct 10, and receives light emitted from the wall surface 11. That is, an incident window (not shown) through which light enters is provided on the surface of the light receiving unit 2 that faces the wall surface 11.
Furthermore, when the duct 10 is formed in the shape of a square cylinder composed of four wall surfaces 11 as shown in FIG. 2, the light receiving portions 2 are arranged on the respective wall surfaces 11 adjacent to each other.

The light splitting unit 3 splits light emitted from the wall surface 11 and guides the light after the splitting to the analysis unit 4.
In addition, a well-known thing can be used as the spectroscopy part 3, and it does not specifically limit.

On the other hand, an optical fiber A that guides the light incident on the light receiving unit 2 to the spectroscopic unit 3 is provided between the light receiving unit 2 and the spectroscopic unit 3, and between the spectroscopic unit 3 and the analysis unit 4, An optical fiber B that guides the split light to the analysis unit is provided.
In addition, as optical fiber A and B, a well-known optical fiber can be used and it does not specifically limit.

  The analysis unit 4 detects the light split by the spectroscopic unit 3 and calculates the temperature of the exhaust gas flowing through the duct 10. A specific calculation method of the exhaust gas temperature performed in the analysis unit 4 will be described later.

Next, an exhaust gas temperature measuring method in the temperature measuring apparatus 1 having the above-described configuration will be described.
In this embodiment, since the light emission distribution (wavelength dependence) of the light emitted from the wall surface 11 of the duct 10 is unknown, the light emission distribution is approximated using a polynomial (for example, a quadratic expression to a ninth order expression). Yes. That is, the error between the approximate light emission distribution and the theoretical absorption band (with temperature dependence) of the gas flowing in the duct 10 and the actually measured light emission distribution is minimized. The temperature of the exhaust gas flowing in the duct 10 is determined by obtaining the temperature of

FIG. 3 is a schematic diagram illustrating a state in which light emitted from the wall surface of the duct enters the light receiving unit.
Generally, light is emitted from the wall surface 11 of the duct 10, and the light enters the light receiving unit 2 as shown in FIG. 3. FIG. 3 shows a case where light emitted from a part of the wall surface 11 facing the wall surface 11 on which the light receiving unit 2 is disposed and a part of the adjacent wall surface 11 is incident on the light receiving unit 2. In FIG. 3, i = 1, 2, 3,..., N indicates the number of the measurement line, and j = 1, 2, 3,..., N indicates the number of the measurement point. It is. A measurement point is a point where two measurement lines intersect.

Here, the light emitted from the wall surface 11 passes through the exhaust gas flowing inside the duct 10 and enters the light receiving unit 2. Therefore, a part of the light incident on the light receiving unit 2 is absorbed by a component contained in the exhaust gas, for example, water vapor.
In addition, in order to specify the temperature measurement location on the wall surface 11, confirmation light such as laser light may be incident on the optical fiber A, and there is no particular limitation.

FIG. 4 is a graph showing an actually measured emission spectrum acquired by the analysis unit.
The light related to one measurement line incident on the light receiving unit 2 enters the spectroscopic unit 3 through the optical fiber A, and is split in the spectroscopic unit 3. The split light related to one measurement line enters the analysis unit 4 via the optical fiber B, and the analysis unit 4 measures the actually measured emission spectrum RS as shown in FIG. The function Fi (X) is acquired (acquisition step).

  Here, the actually measured emission spectrum RS is a spectrum in which the emission spectrum WS of the light emitted from the wall surface 11 and the absorption spectrum (measured absorption spectrum) relating to the gas flowing in the duct 10 are combined.

On the other hand, the analysis unit 4 approximates the light emission distribution of the light emitted from the wall surface 11 of the duct 10, that is, the light emission spectrum WS, with a signal intensity polynomial Di (X) related to the wavelength X described below.
Di (X) = a ₀ i + a ₁ iX + a ₂ iX ² +... + A ₉ iX ⁹
Here, a ₉ from a ₀ is the coefficient of the polynomial, i is a measurement line number.
The order of the polynomial may be any order from the second order to the ninth order, and is not particularly limited.

Furthermore, the analysis unit 4 obtains a function Yij (X, Tij) of the intensity signal related to the wavelength X of the theoretical absorption spectrum of the gas contained in the exhaust gas flowing through the duct 10, in this embodiment, water vapor.
Here, T is the temperature of water vapor, i is a measurement line number, and j is a measurement point number. Therefore, Yij (X, Tij) is also a function relating to the temperature T and a function at the measurement point j of each measurement line i.

Then, the theoretical emission spectrum (signal intensity related to the wavelength X) in each measurement line i can be expressed by the following function.
Di (X) × ΣYij (X, Tij)
That is, it is represented by the product of the polynomial Di (X) of the signal intensity relating to the wavelength X and the sum of the measurement point number j in the function Yij (X, Tij) of the theoretical absorption spectrum of water vapor (intensity signal relating to the wavelength X). be able to.

The analysis unit 4 uses computer tomography and the method of least squares to determine the temperature Tij that minimizes the error between the theoretical emission spectrum and the actually measured emission spectrum RS in each measurement line i obtained through the above-described process. Is calculated (calculation step).
Σ (Fi (X) −Di (X) × ΣYij (X, T)) ²

  Here, when calculating the temperature Tij, it is also conceivable to use an absorption spectrum of water vapor contained in the exhaust gas (for example, absorption bands of 2700 nm, 1900 nm, and 1330 nm).

FIG. 5 is a graph for explaining a state in which the light absorption amount is saturated.
However, when measuring the temperature of the exhaust gas (water vapor) flowing through the duct 10 of a boiler or chemical plant, there are the following disadvantages. That is, the duct 10 has a diameter of several meters to 10 meters, and when the temperature of the water vapor (exhaust gas) is measured using the above-described wavelength, the light absorption amount is saturated as shown in FIG. It becomes difficult to analyze the temperature of the exhaust gas (water vapor) flowing through the duct 10.

FIG. 6 is a graph illustrating an absorption band of water vapor existing from 800 nm to 1000 nm.
On the other hand, the absorption band (see FIG. 6) in the range of about 800 nm to about 1000 nm in water vapor has a small light absorption coefficient and has absorption bands with different absorption amounts. Even if the temperature, the diameter of the duct 10 or the concentration of water vapor changes, a suitable absorption spectrum can be measured and the temperature can be measured.
As shown in FIGS. 7 to 9, the water vapor absorption spectrum in the wavelength range from about 750 nm to about 850 nm changes with changes in temperature. That is, since it has temperature dependence, the temperature of water vapor (exhaust gas) can be measured using this.

  According to said structure, in order to measure the light emitted from the wall surface 11 and which passed exhaust gas (water vapor), without using the structure which irradiates exhaust gas (water vapor) with measurement light, The temperature can be measured. Therefore, the components in the temperature measuring device 1 can be reduced, and the temperature can be measured at a low cost. Furthermore, when the temperature is measured, it is only necessary to arrange the light receiving unit 2 in the duct 10, the number of components arranged in the duct 10 can be reduced, and the temperature can be easily measured.

  Specifically, the temperature of water vapor can be measured by using the light absorption characteristics of water vapor contained in the exhaust gas, that is, the temperature dependence in the absorption spectrum. Therefore, if the absorption spectrum is known in at least one of a plurality of types of gases (for example, water vapor) flowing through the duct 10, the temperature of the water vapor can be obtained. That is, the measured absorption spectrum for water vapor and the theoretical absorption spectrum at a plurality of predetermined temperatures are compared, and the predetermined temperature for the theoretical absorption spectrum with the smallest error is obtained as the temperature closest to the above-described gas temperature. be able to.

  Further, by measuring the temperature of the exhaust gas (water vapor) based on the measured emission spectrum RS including the measured absorption spectrum and the theoretical emission spectrum, the temperature of the exhaust gas (water vapor) based only on the absorption spectrum. Compared with the method of measuring the temperature, the temperature of the exhaust gas (water vapor) can be determined more accurately. For example, not only by comparing the wavelength at the peak of the absorption spectrum, but also by comparing the magnitude of the absorption spectrum, that is, the rate of decrease in intensity from the emission spectrum related to the intensity of light emitted from the wall surface 11, etc. In addition, the temperature of the exhaust gas (water vapor) can be obtained.

On the other hand, since the temperature of the exhaust gas is measured using light that has passed through the exhaust gas (water vapor) emitted from the wall surface 11, the temperature distribution in the exhaust gas flowing through the duct 10 can be measured inexpensively and easily. That is, since light is emitted from all of the wall surface 11 surrounding the exhaust gas, the exhaust gas (only by changing the light measuring direction in the light receiving unit 2 or changing the light receiving unit 2 for measuring light). The temperature distribution of water vapor) can be measured.
Furthermore, since the temperature of the exhaust gas (water vapor) is measured using the light emitted from the wall surface 11 and passed through the exhaust gas (water vapor), the flow of the exhaust gas in the duct 10 is not obstructed, and the exhaust gas is constantly The temperature can be measured.

FIG. 10 is a schematic diagram for explaining another embodiment of the light receiving unit in FIG.
As shown in FIGS. 2 and 3, the light receiving unit 2 has a temperature distribution of exhaust gas 2 on a plane orthogonal to the direction in which the duct 10 extends (on the paper surface of FIGS. 2 and 3). As shown in FIG. 10, the temperature distribution of the exhaust gas flowing in the duct 10 including the direction in which the duct 10 extends can be measured three-dimensionally. Well, not particularly limited.

FIG. 11 is a schematic view for explaining still another embodiment of the light receiving unit in FIG.
Furthermore, as shown in FIG. 11, the condensing optical system 21 is disposed in the light receiving unit 2, and the optical fiber A is a bundle fiber that is a set of single fibers A <b> 1, and the single wire A <b> 1 is directed toward the condensing optical system 21. It may be arranged so as to spread, and is not particularly limited.

DESCRIPTION OF SYMBOLS 1 Temperature measuring device 2 Light-receiving part 3 Spectrometer part 4 Analysis part 10 Duct (flow path)
11 Wall surface

Claims (5)

A light receiving unit that is attached to one wall surface of the flow path through which the fluid flows, is emitted from the other wall surface of the flow path, and receives light that has passed through the fluid;
A spectroscopic unit that splits light incident on the light receiving unit;
While obtaining at least an actually measured absorption spectrum that is an absorption spectrum related to the gas from the light split by the spectroscopic unit,
Comparing the theoretical absorption spectrum of the gas at a given temperature and the measured absorption spectrum;
An analysis unit for obtaining the predetermined temperature at which an error between the theoretical absorption spectrum and the actually measured absorption spectrum is minimized;
A temperature measuring device is provided. An acquisition step of measuring the light emitted from the wall surface of the flow path through which the gas flows and passing through the gas, and obtaining an actual absorption spectrum that is an absorption spectrum for the gas;
Comparing the theoretical absorption spectrum of the gas at a given temperature and the measured absorption spectrum;
A calculation step for obtaining the predetermined temperature at which an error between the theoretical absorption spectrum and the actually measured absorption spectrum is minimized;
A temperature measuring method characterized by comprising: In the acquisition step, a spectrum relating to the intensity of light that has passed through the gas, wherein a measured emission spectrum including the measured absorption spectrum is acquired,
In the calculation step, an approximate spectrum that approximates an emission spectrum relating to the intensity of light emitted from the wall surface, and a theoretical emission spectrum is calculated based on the theoretical absorption spectrum,
3. The temperature measuring method according to claim 2, wherein the predetermined temperature at which an error between the theoretical emission spectrum and the actually measured emission spectrum is minimized is obtained. The temperature measurement method according to claim 2, wherein the absorption spectrum is an absorption spectrum related to water vapor (H ₂ O). The temperature measurement method according to claim 2, wherein the absorption spectrum is an absorption spectrum related to water vapor (H ₂ O) in a wavelength range of 750 nm to 850 nm.

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