JPH0743117B2 - Boiler combustion condition monitoring device - Google Patents

Description

The present invention relates to an apparatus for monitoring a combustion state of a boiler, and more particularly to a boiler combustion state monitoring apparatus suitable for estimating exhaust gas components discharged from the boiler. .

[Conventional technology]

The conventional device, for example, as described in JP-A-60-228818, measures the flame shape in the vicinity of the burner outlet as a luminance distribution, extracts the oxidizing flame shape from the measured flame, and extracts the burner outlet portion. It is a device to estimate the unburned content in ash based on the information on the position between the oxidative flame and the oxidative flame. However, no consideration is given to the influence of the fuel volume and the combustion flame temperature distribution, which strongly influence the unburned matter in ash.
Further, there is a problem that it cannot be applied to other flames than one in which an oxidizing flame exists one by one with a burner axis as a boundary.

[Problems to be Solved by the Invention]

Since the above-mentioned conventional technique evaluates the combustion state with only one cross-sectional shape of the burner combustion flame, that is, in a plan view, the characteristics of other portions of the combustion flame that do not appear in the cross-sectional shape of this one combustion flame However, it was not possible to accurately evaluate the combustion state of the boiler.

An object of the present invention is to provide a boiler combustion state monitoring device capable of three-dimensionally grasping the characteristic amount of the burner combustion flame relating to the combustion state of the boiler and accurately monitoring the combustion state of the boiler.

[Means for Solving the Problems]

A boiler state monitoring device according to the present invention for achieving the above object is a boiler combustion state monitoring device for monitoring a combustion state of a power generation boiler including a burner, wherein: (a) a direction perpendicular to a central axis of the burner, An image pickup means for picking up an image of the flame shape on the side surface of the entire combustion flame of the burner; and (b) dividing the flame shape picked up by the image pickup means into a plurality of regions for each predetermined temperature range to obtain a temperature distribution of the flame shape. (C) The flame shape is divided into a plurality of sections on a plane orthogonal to the central axis of the burner, and the cross-sectional temperature distribution of the combustion flame on each of the divided planes is defined as the center. A distance from the axis to a boundary line of a temperature region existing in the temperature distribution obtained by the temperature distribution calculating unit, and a cross-section temperature distribution estimating unit estimating based on the predetermined temperature range, (D) Based on a plurality of cross-section temperature distributions estimated by the cross-section temperature distribution estimation means, and a predetermined relational characteristic between the distance in the central axis direction of the burner and the unburned ash content in the combustion flame. And means for estimating the combustion state of the boiler.

[Action]

According to the present invention, the temperature distribution of the combustion flame in the cross section orthogonal to the central axis of the burner is estimated, a plurality of this cross section temperature distribution is detected from the vicinity of the burner outlet to the wake end of the combustion flame, and the plurality of cross sections are detected. Since the combustion state of the boiler is evaluated based on the temperature distribution and the relationship characteristics between the distance in the central axis direction of the burner and the unburned content in the ash in the combustion flame, it can be grasped with one cross-sectional shape of the combustion flame. It was possible to grasp the three-dimensional distribution of the characteristic amount (temperature, brightness, etc.) of the combustion flame related to the boiler combustion state, which was not available, and the fuel ejected from the burner from the burner outlet to the downstream end of the combustion flame. It is possible to accurately estimate the combustion state of, especially unburned ash content in the combustion flame.

〔Example〕

An embodiment of the present invention will be shown below in FIG. In FIG. 1, 1 is a burner, 2 is a flame, 3 is a furnace, 4 is a cooling device,
5 is an image fiber, 6 is a spectroscope, 7 is a half mirror, 8 is an interference filter, 9 is an ITV camera, 10 is an analog / digital conversion device, 11 is a digital image storage device, 12
Is a calculator, 13 is a display device, 14 is a wavelength λ ₂ filter, 15 is the i-th section of the flame temperature distribution round slice, 16 is the flame temperature distribution round slice cross-sectional area, and 17 is a flame temperature distribution evaluation calculation processing conceptual diagram.

As shown in FIG. 1, the combustion flame 2 during the operation of the boiler is measured by using two image fibers 5 for the flame near the burner and the flame in the wake region of the flame, and each of them is measured, for example, at a wavelength of 60 through the spectroscope 6.
The brightness distribution of 0,700 nm is divided and each is photographed by the ITV camera 9. It is also possible to measure the flame with one image fiber by using a wide-angle lens for the image fiber objective lens system. The video signal is converted into digital image data by an analog / digital conversion device 10 and stored in a digital image storage device 11.

The timing for converting the video signal to be input to the digital image storage device 11 into analog / digital is analog / digital.
The timing signal 18 for executing the digital conversion is used. In this embodiment, the timing signal 18 for executing the analog / digital conversion is supplied from the computer 12, but the effect does not change even if it is supplied by the manual operation.

Burner neighborhood image stored in the digital image storage device 11
A temperature distribution is calculated by a computer using the brightness information of wavelengths of 600 and 700 nm, respectively, in each image of the wake region in the flame. The method of calculating the temperature at each coordinate point of the flame digital image is shown below. It should be noted that the same effect can be obtained by selecting two arbitrary wavelengths at the time of measurement.

Using Wein's equation, the relationship between the brightness and the temperature at each coordinate point at wavelengths of 600 and 700 nm is expressed by equations (1) and (2).

Where R ₁ (i, j): luminance at wavelength 700nm in (i, j) coordinates R ₂ (i, j): luminance at wavelength 600nm in (i, j) coordinates ε ₁ : effective emissivity at wavelength 700nm ε ₂ : Effective emissivity at wavelength 600 nm λ ₁ : Wavelength 700 nm λ ₂ : Wavelength 600 nm T (i, j): Temperature at (i, j) coordinates c ₁ : First radiation constant (3.7403 × 10 ^-5 erg · cm) ² / s) c ₂ : Second radiation constant (1.4387cm / K °) Take the luminance ratio of wavelength (700,600nm) of (i, j) coordinate of formulas (1) and (2), and calculate (i, j) coordinate. When the temperature T is solved, the equation (3) is obtained.

The temperature at each coordinate can be obtained by performing the calculation shown in the formula (3) for all the coordinate points with a computer.

The method of obtaining the flame temperature distribution by applying the two-color pyrometer method using the luminance distribution of two wavelengths measured from the flame has been described above, but the temperature distribution is also obtained from the luminance distribution of one wavelength from the flame. The method is shown below.

The relationship between flame wavelength, brightness (radiation intensity), and temperature can be expressed by Planck's equation (4).

Where λ: wavelength (μm) T: absolute temperature K ° R: temperature of wavelength λ c1: first radiation constant (3.7403 × 10 ^-5 erg · cm ² / s) c2: second radiation constant (1.4387 cm · K) °) If the equation (4) is applied and the flame image temperature information is applied to all points in the equation (5), the flame temperature distribution can be obtained.

As described above, in order to realize the expression (5), either one of the two measurement wavelengths in FIG. 1 may be used. It can also be realized by the system configuration shown in FIG.

Hereinafter, the flame temperature volumetric evaluation is performed according to the flow chart shown in FIG. 2 by using the calculated temperature distribution of the flame near the burner and the wake region in the flame.

1.100: Connect the flame temperature distribution near the burner and the wake region temperature distribution in the flame.

The flame temperature distribution near the burner and the wake region temperature distribution in the flame are connected so as to form one flame temperature distribution.

2.110: Divide the flame temperature distribution into multiple areas for each set temperature range.

Assuming that the flame shown in FIG. 4 (a) has a temperature distribution in the temperature range of 1000 ° K to 1800 ° K, if an isothermal line is drawn every 200 ° K for example, it is shown in FIG. 4 (b). Thus, the temperature range is divided into a plurality of regions. By such a method, a certain setting range is divided into a plurality of areas. The set temperature range for dividing the region may be determined in consideration of the minimum temperature value and the maximum temperature value of the flame temperature distribution.

Hereinafter, description will be given using the flame having the temperature distribution shown in FIG.

3.120: Obtain an average temperature of each region decomposed into a plurality of i-th intervals.

As shown in FIG. 5 (a), when only the i-th section is extracted from the flame temperature distribution, FIG. 5 (b) is obtained, and the average temperature is obtained for each temperature region in the i-th section. In FIG. 5 (b),
The average temperature is obtained for each of the three regions.
(Here, the i-th section represents the i-th section from the burner outlet of the section by dividing the flame image of the burner combustion flame from the vicinity of the burner outlet to the downstream end of the combustion flame into a plurality of sections.) Taking the region 19 of flame temperature 1000 to 1199 ° K as an example to find the temperature, the flame temperature 1000 to 1199 ° K region
To obtain the average temperature of 19, use equation (6).

The frequency in the flame temperature range of 1000 to 1199 ° K is the number of temperature information in the flame temperature range of 1000 to 1199 ° K.

4.130: The flame is concentric, and the product of the average temperature function and the frequency of each temperature region in the i-th section is calculated.

Assuming that the flames are concentric circles, the i-th section 15 of the flame temperature distribution shown in FIG. 6 (a) (same as the temperature distribution shown in FIG. 4)
The cross section of can be divided into the temperature regions shown in FIG. 6 (b). Similarly, the cross section of the j-th section 23 can be divided into the temperature regions shown in FIG. 6C and the k-th section 24 can be divided into the temperature regions shown in FIG. 6D. A method for obtaining the product T _i of the function of the average temperature and the frequency in each temperature region is shown in the equation (7) using FIG. 7 which is a cross section of the i-th section.

T _i = {x (T _i1 −T ₀ ) ^α・ S _i1 } + y (T _i2 −T ₀ ) ^β・
S _i2 } + {z (T _i3 −T ₀ ) ^γ・ S _i3 }… (7) where T _{i1 is} flame temperature 1000 to 1199 ° K region average temperature T _{i2 is} flame temperature 1200 to 1399 ° K region average temperature T _i3 : Flame temperature 1400 to 1599 ° K region average temperature T ₀ : Ignition temperature S _i1 : π (l ² −m ² ): Flame temperature 1000 to 1199 ° K region S _i2 : π (m ² −n ² ): Flame Temperature 1200 to 1399 ° K region S _i3 : πn ² : Flame temperature 1400 to 1599 ° K region x, y, z: Coefficients (however, x, y, z> 0) α, β, γ: Coefficients (burner structure, charcoal As described above, the product T _i of the function of the average temperature in the i-th section and the frequency was obtained as described above. The same method was used to calculate the product from the burner outlet (first section) to the flame end (first section). The product of the function and the frequency of each average temperature up to n intervals)
Calculate T _{1 to} T _{i to} T _n .

5.140: The unburned ash content estimation index is calculated using the product of the function of the average temperature and the frequency of each section from the 1st section to the nth section.

Hereinafter, a method of obtaining an unburned carbon content estimation index in ash by using the product of the average temperature function and the frequency of each section will be described.

The product T _i of the function of the average temperature in the i-th section and the frequency is considered to be a combustion index representing the combustion state (combustion volume / combustion temperature distribution) in the i-th section. For example, in the case of a pulverized coal combustion flame, if the ignition is not successful in the vicinity of the burner, the volatile component combustion is not promoted by the extraction of the volatile component, so the flame temperature does not rise and the combustion volume is considered to be small, and T _i becomes small. In addition, T _i is considered to be small unless combustion is promoted due to the effects of volatile matter extraction near the burner in the middle flame region and diffusion of pulverized coal with oxygen in the latter stream region of the flame.

Here, Fig. 8 shows how unburned ash content decreases in the combustion process. The unburned content in ash is plotted on the vertical axis and the burner axial distance is plotted on the horizontal axis, and the experimental results in the experimental furnace are plotted. As can be seen from this figure, the unburned content in ash continuously decreases as combustion progresses.

From the above, the product T _i of the function of the average temperature of each section and the frequency is set as the combustion rate in each section, the combustion component of each segment is derived, and the final unburned ash content is estimated. The amount of combustion in each section is defined as in equation (6).

I-th section combustion component = T _i × remaining unburned content immediately before i-th segment (8) The following is an example of pulverized coal combustion of Saxon bale coal.

1st section combustion (combustion immediately after ignition) = T ₁ × (remaining unburned content when combustion is zero: 82%) 2nd section combustion = T ₂ × (82 − 1st section combustion) I-th section combustion = T _i × (remaining unburned content up to i-1 section) n-th section combustion (section immediately before the end of combustion) = T _n × (remaining unburned content up to n-1 section) combustion Remaining unburned content at the end = (remaining unburnt content up to n-1 section)-(nth section combustion content) (9) Thus, the unburnt ash content at the end of combustion is the combustion of each section. Minutes can be obtained and estimated by the equation (9). Here, the reason why the residual unburned content becomes 82% when the combustion content is zero is shown. Unburnt content in ash is defined as in equation (10).

However, μ: unburned rate A: ash content ratio of raw coal The raw coal ratio of Saxon Bale coal is 18%, and when the burned content is zero, the unburned rate is 100 [%]. The value obtained by substituting these numerical values is 82%.

Although the method of estimating the unburnt content in ash using temperature has been described above, the unburned content in ash can be estimated by a similar method using the flame intensity distribution.

6,150: Display the result of estimation of unburned ash content on the display.

The ash unburnt content estimation result obtained above is displayed on the CRT.
The flame state of any part of the flame can be known by coloring the flame temperature distribution shown in FIG. 5 (a) for each set temperature region and displaying the combustion rate of the selected part. .

As above, the method of estimating the unburned ash content for one combustion flame has been shown, but the actual can is composed of multiple burners (m stages x n
Row) The combustion state of each stage is different. Therefore, in order to estimate the unburned ash content of the entire can, it is necessary to measure the combustion flame at least for each stage to estimate the unburned ash content.

〔The invention's effect〕

As described above, according to the present invention, since the three-dimensional distribution of the characteristic amount of the combustion flame related to the boiler combustion state can be extracted, the characteristic amount can be grasped over the entire combustion flame, and the boiler combustion state can be accurately generated. Can be monitored.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a schematic process flow chart of a computer, FIG. 3 is a block diagram when measuring a flame with a single wavelength, and FIG. 4 is a flame temperature region. Conceptual diagram of division,
FIG. 5 (a) is a conceptual diagram of the flame temperature distribution on the image memory, FIG. 5 (b) is an explanatory diagram of section i, FIG. 6 (a) is the flame temperature distribution, and FIG. 6 (b) is i. FIG. 6 (c) is a sectional view when the section is concentric, and FIG. 6 (d) is a sectional view when the section k is concentric. The figure shows a sectional view when the i-th section is a concentric circle.
The figure is a characteristic diagram showing a decrease in the unburned ash content with respect to the burner axial distance. 1 ... Burner, 2 ... Flame, 3 ... Furnace, 4 ... Cooling device, 5 ... Image fiber, 6 ... Spectroscope, 7 ...
Half mirror, 8 ... Wavelength λ ₁ filter, 9 ... ITV camera, 10 ... Analog / digital conversion device, 11 ... Digital image storage device, 12 ... Computer, 13 ... Display device, 14
...... Wavelength λ ₂ filter, 15 …… Flame temperature distribution rounded i
Section, 16 …… Flame temperature distribution cross section, 17 …… Conceptual diagram of computer processing, 18 …… Analog / digital conversion timing signal, 19 …… Flame temperature 1000 to 1199 ° K region, 20 …… Flame temperature 1200 to 1399 ° K area, 21 ... Flame temperature 1400 to 1599 ° K area, 22 ... Flame temperature 1600 to 1800 ° K area, 23 ... Image memory J coordinate, 24 ... Image memory I coordinate, 25 ... i Luminance information , 26 …… section j, 27 …… section k.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenjiro Takahashi, No. 17 Hosoda, Hosoda, Yoshidahama, Shichigahama-cho, Miyagi-gun, Miyagi Prefecture (56) References JP-A-60-244821 (JP, A) JP-A-61 -93311 (JP, A)

Claims (1)

[Claims] 1. A boiler combustion state monitoring device for monitoring a combustion state of a power generation boiler equipped with a burner, comprising: (a) determining a flame shape of a side surface of an entire combustion flame of the burner from a direction substantially perpendicular to a central axis of the burner. Image capturing means for capturing an image; (b) temperature distribution calculation means for dividing the flame shape captured by the image capturing means into a plurality of regions for each predetermined temperature range to obtain a temperature distribution of the flame shape; The flame shape is divided into a plurality of sections on a plane orthogonal to the central axis of the burner, and the cross-sectional temperature distribution of the combustion flame on each of the divided surfaces is obtained from the central axis by the temperature distribution calculating means. Section temperature distribution estimating means for estimating based on the distance to the boundary line of the temperature region existing in the temperature distribution and the predetermined temperature range; and (d) estimation by the section temperature distribution estimating means. Means for estimating the combustion state of the boiler based on a plurality of cross-sectional temperature distributions, a predetermined distance between the burner in the direction of the central axis of the burner, and a relationship characteristic between the unburned content in ash in the combustion flame. A boiler combustion state monitoring device comprising: