JPH0582893B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a particle temperature distribution measuring method applied to combustion monitoring of a pulverized coal-fired boiler furnace. [Prior Art] Fig. 3 shows a particle temperature distribution measurement method that has been conventionally used for the purpose of monitoring combustion in pulverized coal-fired boiler furnaces. The light emitted from the pulverized coal particles 3 in the pulverized coal combustion flame 2 located on the central axis of the cylindrical furnace 1 is transmitted through a lens 4.
is transmitted and divided into two systems by a half mirror 5. After the light reflected by the half mirror 5 passes through the lens 4, it is converted to a wavelength λ ₁ by a monochromator 6 with a wavelength λ _1.
Only the monochromatic light of is extracted, and the detector 7 and the electrometer 8
The light intensity of wavelength λ ₁ emitted by pulverized coal particles 3 is
I〓 ₁ is detected. On the other hand, the light transmitted through the half mirror 5 passes through the lens 4 and enters the monochromator 9 with a wavelength λ ₂ close to the wavelength λ ₁ , where only the monochromatic light with the wavelength λ ₂ is extracted, and the detector 7 and the electrometer 8 The light intensity I〓 ₂ of wavelength λ ₂ emitted by the pulverized coal particles 3 is detected. The radiation intensity I〓 at the wavelength λ emitted from the pulverized coal particles 3 is given by the emissivity at the wavelength λ being ε〓, and the temperature of the particle being T _p
Then, according to Planek's formula, I〓=ε〓・C ₁ /λ ⁵・1/e ^C2/ 〓 ^TP p−1 ……(1) Here, C ₁ and C ₂ are constants, and C ₁ = 3.2179 ×10 ³ (Kcalμm ⁴ /m ² h), C ₂ = 1.43388×10 ⁴ (μm ⁶ K),
e ^C2/ 〓 ^Tp is on the order of 10 ³ or more. Therefore, equation (1) is transformed as follows. I〓＝ε〓・C ₁ /λ ⁵・e ^C2/ 〓 ^Tp ...(2) Therefore, if the emissivity at wavelengths λ ₁ and λ ₂ are ε〓 ₁ and ε〓 ₂ , then I〓 ₁ / I〓 ₂ = [ε〓 ₁・λ ₁ ^-5 / (ε〓 ₂・λ ₂ ^-5 )]・e−C ₂ /TP・λ ₂ −λ ₁ /λ ₁ λ ₂ ...(3) Therefore , 2 wavelengths λ ₁ in the range that can be considered as ε〓 ₁ = ε〓 ₂ ,
At λ ₂ , ln(I〓 ₁ /I〓 ₂ ) = −5ln(λ ₁ /λ ₂ )−C ₂ /T _p・λ ₂ −λ ₁ /λ ₁ λ ₂ ...(
4) Therefore, by calculating ln (I〓 ₁ /I〓 ₂ ) using the amplifier 10, the particle temperature T _p in the pulverized coal combustion flame 2 can be found. [Problem to be solved by the invention] When the concentration distribution and particle temperature distribution in the pulverized coal combustion flame are uneven, in the conventional measurement method, the light intensity from the particles detected by the detector is on the optical path. It is the sum of the amount of radiation that has reached the detector from all the particles that are present, and even if you focus on the particle you are trying to find with a lens, other particles that exist between that particle and the detector will interfere with the radiation. It is impossible to know the particle temperature at any position on the optical path unless a measurement method that takes particle concentration into account is considered because the true light intensity from the particle cannot be detected. The present invention has been made to solve these problems, and its purpose is to be able to measure the concentration distribution of particles floating in a non-uniform distribution field and the particle temperature distribution, and to measure the particle temperature distribution. The purpose of this study is to provide a particle temperature distribution measurement method that is effective for high-efficiency operation and optimal design of furnaces through combustion analysis. [Means for Solving the Problems] In order to achieve the above object, in the particle temperature distribution measuring method of the present invention, in addition to information on the light intensity of two wavelengths emitted from particles, laser light is Information on the intensity of light that irradiates the floating field and passes through the floating field is taken in. Furthermore, these three pieces of information are obtained in multiple directions, and these data are
Tomography) calculation processing. [Function] Therefore, according to the measurement method of the present invention, a laser beam is irradiated onto a floating field of particles, and information on the overall particle concentration on the optical path can be obtained from data on the transmission attenuation characteristics of the laser beam in the floating field. Select two wavelengths of the emitted light from the floating field, take in the two pieces of information on the entire particle temperature on the optical path in multiple directions, and calculate the particle temperature at any position by performing CT calculation processing on them. It will be done. [Example] An example of the method of the present invention will be described based on FIGS. 1 and 2. The air-borne pulverized coal is blown from the burner 21 into the cylindrical furnace 22, where it forms a combustion flame. From the Ar laser beam oscillator 24 located at an arbitrary point outside the furnace in the cross section 23 (- cross section) perpendicular to the central axis of the cylindrical furnace 22, toward the furnace center in the same cross section, that is, in the θ ₀ direction, the cylindrical Injected through the hole 25 provided in the furnace wall of the furnace 22
The Ar laser beam 27 is obstructed by particles 28 on the way and its light intensity is attenuated, and then exits from the furnace through a hole 26 provided in the furnace wall at a position opposite to the hole 25 . Ar that went out of the reactor
A part of the laser beam 27 is reflected by the laser beam selection half mirror 29, passes through the lens 30, and has a wavelength λ _a
(=4880Å) monochromator 31, detector 32,
The light intensity _I〓a is detected by the electrometer 33.
The following relationship exists between this light intensity _I〓a and the light intensity _I′〓a generated by the Ar laser beam oscillator 24. I〓 _a ＝I′〓 _a・e−(∫ ^L ₀ kπ／4dp ² Ndl) ……(5) Here, K is the attenuation coefficient, dp is the diameter of the particle, and N
is the particle concentration and L is the optical path length. Here, since I′〓 _a is known, the intensity attenuation rate F _j is calculated using the following formula,
It is stored in the memory of the computer 37. F _j = −ln {(I〓 _a /I′〓 _a ) _j } =∫ ^L _O kπ/4dp ² Ndl =∫ ^L _O f _l dl= Σ ⁱ fi・Δli ...(6) Next, Ar laser The optical oscillator 24 and the Ar laser beam selection half mirror 29 are translated in the γ direction by Δγ, the transmitted intensity I〓 _a of the Ar laser beam 27 is measured in the same manner as above, and F _j is calculated using equation (6). and stores it in the memory of the computer 37. By repeating this operation, the F _j distribution in the θ ₀ direction is determined. When the F _j distribution in the θ ₀ direction is determined, the pair of Ar laser beam oscillators 24 and the Ar laser beam selection half mirror 29
Rotate by Δθ in the θ direction, obtain the F _j distribution in the (θ ₀ + Δθ) direction in the same way as above, and repeat these operations up to the (θ ₀ + 360° − Δθ) direction to obtain the F _j distribution in all directions. demand. Since Δl _i in equation (6) is known from the size of the mesh, the light absorption coefficient f _i distribution within the above-mentioned cross section is determined by CT calculation processing by the computer 37. Here, when storing the value of F _j in the computer 37, the radiation light from all the particles existing on the same optical path is further reflected and transmitted by a half mirror 34 that is different from the laser beam selection half mirror 29. The reflected light passes through the lens 30 and has a wavelength of λ ₁ (5890 Å, which is the extremely strong wavelength range of the radiant light from the combustion flame).
A monochromator 35, a detector 32, and an electrometer 33 detect the light intensity I〓 ₁ with a wavelength λ ₁ (wavelengths in the yellow to red range excluding the front and rear), and a half mirror 34
The transmitted light passes through a lens 30, and a monochromator 36 with a wavelength λ ₂ close to λ ₁ , a detector 32, and an electrometer 3
3, the light intensity I〓 ₂ of wavelength λ ₂ is detected. Now, when the radiant energy I'〓 from a particle at a distance l from the furnace wall 26 reaches the detector due to attenuation by other particles along the optical path, the energy I〓 is I〓=I′〓・e−(∫ ^L _l kπ/4dp ² Ndl) = I′λ・e−(∫ ^L ₀ f _l dl ……(7) Therefore, by integrating over the entire optical path length, (I〓 ₁ ) _j , (I〓 ₂ ) _j is as follows.

[ka]

[C] Therefore, when finding F _j using the Ar laser light oscillator 24 and the Ar laser light detector, (I〓 ₁ ) _j ,
(I〓 ₂ ) _j is also found, and (I〓 ₁ ) _j ,
(I〓 ₂ ) Find the distribution of _j . Δl _i in equations (8) and (9) is the size of the mesh, and if f _i is calculated by CT calculation processing regarding F _j beforehand, then

〔Effect of the invention〕

With the present invention, it is possible to measure particle concentration distribution and particle temperature distribution with non-uniform distribution, which could not be determined using conventional measurement methods, and to achieve high efficiency operation of furnaces through combustion analysis of pulverized coal combustion fields. This can have a great effect on optimal design and the like.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a cylindrical furnace section showing an embodiment of the method of the present invention, Fig. 2 is a cross-sectional view along the - line in Fig. 1 and an outline of the entire process, and Fig. 3 is FIG. 2 is a schematic explanatory diagram illustrating a conventional method. 22...Cylindrical furnace, 24...Ar laser oscillator,
27...Ar laser beam, 28...Particle, 31,3
5, 36... Monochromator, 33... Electrometer,
37...Calculator.

Claims (1)

[Claims] 1 A laser beam is irradiated from multiple directions across a floating field where particles are suspended, and based on the laser beam intensity attenuation rate data obtained at this time,
CT calculation processing is performed to calculate the light absorption coefficients at the positions where the laser beams intersect, and the beam axis is extended by the intensity of the radiant light of two or more wavelengths of the radiant light emitted from the particles on the laser beam path. Particle temperature distribution measurement characterized in that temperature distribution data of the floating field is obtained by detecting each on the line and performing CT calculation processing based on the detected radiation light intensity data and the light absorption coefficient data. Method.