WO1998040673A1

WO1998040673A1 - Method and device for analyzing combustion and for monitoring flames in a combustion chamber

Info

Publication number: WO1998040673A1
Application number: PCT/DE1998/000690
Authority: WO
Inventors: Thomas Merklein
Original assignee: Siemens Aktiengesellschaft
Priority date: 1997-03-12
Filing date: 1998-03-09
Publication date: 1998-09-17
Also published as: DE19710206A1

Abstract

In order to enable particularly prompt detection of temperature distribution and concentration distribution of reaction products occurring during the combustion process as well as flame parameters (F), the invention provides for an image (B1, B3, B4, B5, B6) of a flame to be picked up, whereby a physical distribution of a combustion-process characteristic parameter for at least one predefined spectral range (203, 204, 205, 206) is determined on the basis of local resolution intensity of said image (B1, B3, B4, B5, B6).

Description

description

Method and device for combustion analysis and flame monitoring in a combustion chamber

The invention relates to a method for combustion analysis in a combustion chamber, in which the temperature and the concentration of at least one reaction product formed in the combustion process are determined. It also relates to a device for carrying out the method and a device for flame analysis and flame monitoring of a burner.

When burning a fossil fuel in a combustion chamber, the constant improvement of the combustion process is the focus of the efforts. In order to achieve a particularly good combustion process with the lowest possible emission of pollutants, in particular CO and NO _x , and a particularly high degree of efficiency with a low flue gas volume flow at the same time, the firing must be optimized by means of a suitable firing control. When fossil fuel or waste is burned, fluctuations in the calorific value of the fuel or the fuel mixture occur due to the different origin of the fuel or due to the heterogeneous composition of the waste. These fluctuations have a negative impact on pollutant emissions. These disadvantages also exist in industrial waste incineration, where usually solid and liquid as well as gaseous fuels are burned at the same time. Knowing the temperature distribution and the concentration profile of the reaction products arising in the combustion process can improve the combustion control and thus improve the combustion process. In the older German application 195 09 412-3 "Method and device for controlling the firing of a steam generator system", a firing control based on knowledge of the temperature distribution and the concentration profile of reaction products formed in the combustion process was proposed. The temperature and the concentration of reaction products are detected by means of at least two optical sensors. However, it is disadvantageous that only one line of the combustion area is detected with these optical sensors or cameras. A multi-dimensional distribution of the combustion characteristics can only be determined by combining several cameras and with considerable computing effort. As a result, the temperature distribution and the concentration distribution, for example of CO and NO _x , are only recorded globally for the entire combustion chamber. The burning behavior of a single burner is not taken into account. In the case of the aforementioned registration, the focus is on the actual value and setpoint formation for the firing control.

DE 38 23 494 A1 also discloses a method for obtaining parameters correlated with target variables of a furnace, in which a beam splitter optical system is arranged between a recording camera and the output end of an endoscope, which generates two beams directed at the camera target. The images taken at different light wavelengths are compared or combined with one another. The aim is not to record measured values that correspond to certain physical quantities. Rather, target parameters are approximately determined using a multidimensional regression analysis. As a result, instead of measuring technical quantities, such as pollutant emissions, these are only estimated. In order to enable fast control of individual burners as well as homogeneous combustion and consequently a reduction in To achieve the formation of pollutants, it is necessary to be able to record the temperature distribution of individual flames and the concentration distribution of reaction products arising in the combustion process in individual flames. In addition, it is necessary for safety requirements to be able to identify and record a flame cut off of individual burners - the flame has extinguished - as quickly as possible, so that the fuel supply for the disturbed burner can be shut off and consequently a safe state of the system can be ensured.

The invention is therefore based on the object of specifying a method for combustion analysis in a combustion chamber, with which at least one parameter characterizing the combustion process, in particular the temperature distribution and the concentration distribution of reaction products formed in the combustion process and parameters of the flame, are recorded particularly quickly. This is to be achieved in a device with particularly simple means.

According to the invention, the first-mentioned object is achieved by a method in which a radiation spectrum of a flame is recorded in the combustion chamber, a plurality of spectral ranges being coupled out by beam splitting of the radiation spectrum, with a respective image for a number of parameters characterizing the combustion process by means of the extracted spectral ranges of the flame is generated, and a spatial distribution of the corresponding parameter is represented in the respective images by means of spatially resolved intensities.

The invention is based on the consideration that the parameters describing the combustion, for example reaction products of the combustion (combustion radicals) or the temperature, can be detected in the emission spectrum of a flame. nen. The combustion radicals, for example NO, CO, C ₂ , CN or CH, each have associated intensity ranges in the associated radiation ranges or spectral ranges with a bandwidth of approximately 5 to 20 n. Analogously to this, the Planck radiation, in particular the particle radiation, which also occurs in the combustion process is used to determine the temperature distribution.

The individual spectral ranges of the respective combustion radicals or the temperature can be separated from one another by filtering out the corresponding spectral ranges of the combustion radicals to be examined or the temperature from the emission or radiation spectrum. On the basis of the spectral ranges separated from one another, individual images of the

Flame for the respective spectral ranges, i.e. for the combustion radicals to be investigated or for the temperature. This means that the concentration profile or the concentration distribution of one or more combustion radicals and the temperature distribution of one or more flames can be recorded quickly and reliably.

By separating at least one specifiable spectral range from the radiation spectrum of the flame, in particular a spatial distribution of individual parameters characterizing the combustion process is determined. For example, by coupling out several spectral ranges, several spatial distributions, e.g. the temperature distribution and the respective concentration distribution of several combustion radicals can be recorded simultaneously.

In order to record in particular the band radiation characteristic of the respective parameter, ie the emission line the corresponding spectral range is coupled out with a bandwidth of approx. 5 to 20 nm.

For the or each combustion radical, a respective narrow-band spectral range with a frequency band of approximately 5 to 20 nm is expediently coupled out of the radiation spectrum. This frequency band corresponds exactly to the specific band on which the combustion radical to be examined or the gas radiates and absorbs. For example, some emission lines of the combustion radicals CO and CH to be investigated for the combustion analysis lie in a band from 445 to 455 nm and from 430 to 440 nm. By means of this emission line lying in the narrow-band spectral range and their intensity, one expediently uses the recorded image of the flame to determine one spatial concentration distribution of the combustion radical to be examined reconstructed by computer tomography. The intensity distribution of the radiation is recorded directly by means of a camera, in particular a CCD camera.

By means of image processing methods, in which, for example, the image field is scanned line by line or point by point, the radiation intensity is electronically amplified and converted into contrasts depending on the intensity, the concentration distribution or the temperature distribution is made recognizable. In addition, geometrical sizes of the flame, e.g. the length of the flame or the speed of its change.

Two narrowband bands are preferred for the temperature

Spectral ranges with a frequency band of approx. 10 nm each are coupled out of the radiation spectrum. These frequency bands lie in particular between two frequency bands of the combustion radicals, in the so-called band-free areas. According to the Planck 'see radiation law lies in the band-free areas only planck radiation, the temperature being determined by forming the ratio of the intentivity values of these areas. By means of the Planck radiation lying in the second spectral range and its intensity, the spatial temperature distribution in the flame is advantageously reconstructed using computer tomography.

In order to be able to guarantee flame monitoring in addition to combustion and flame analysis, a pulsating parameter of the

Flame is monitored and a pulsation parameter is determined. For example, the intensity of the radiation in this third spectral range is detected as a pulsating parameter and the pulsation frequency as a pulsation parameter by means of a measuring module. The fuel supply to the corresponding burner is controlled as a function of the detected and determined pulsation frequency and its change. For example, a low pulsation frequency represents a flame cut, i.e. the flame of the burner to be examined is out. A detected flame arrest then leads to a safe one

Switching command for the non-existent flame of the burner - to shut off the fuel supply of the disturbed burner.

With regard to the device for combustion analysis in a combustion chamber, the above object is achieved with an optical system which comprises an objective for recording a radiation spectrum of a flame in the combustion chamber and a plurality of beam splitters connected downstream of the objective for coupling out a plurality of spectral ranges, one of which Number of parameters of the combustion process to be examined, corresponding number of receiving plates, each of which generates a spatially resolved image of the flame for each parameter, is connected downstream of the beam splitters. Due to the use of the device directly on hot system parts, for example on a boiler, a cooling system is expediently provided. The cooling system for the or each mounting plate comprises a cooling element, for example a Peltier element. Using the Peltier effect, the Peltier element cools down to the ambient temperature, while a heat sink connected to the Peltier element heats up. In addition, the other electronic components belonging to the device are cooled with cooling or purging air.

Depending on the number of parameters of the combustion process to be examined, the device preferably comprises a suitable number of beam splitters for coupling out the respective characteristic spectral ranges of the parameters. In other words, for the division of the radiation spectrum of the flame into the spectral ranges to be examined, corresponding beam splitters are provided, which are transmissive for certain wavelengths. For example, beam splitters with filter values of 360 to 370 nm and 430 to 440 nm are used as coarse filters for the parameters to be examined, in particular for the combustion radicals CO and CH.

In an advantageous embodiment, the beam splitter is dichroic. In other words, in order to be able to uniquely couple out corresponding spectral ranges for parameters to be examined, the beam splitter is designed in such a way that the beam splitter reflects its radiation for a spectral range to be examined and / or, on the other hand, is transparent to another spectral range to be examined. The respective spectral range to be examined can be coupled out practically 100% from the radiation spectrum of the flame. In addition, other optical devices, for example filters, in particular so-called fine filters with a certain cut-off wavelength, or prisms or gratings can be used. In order to be able to determine the spatial distribution of several parameters characterizing the combustion process at the same time, a number of spatially separated recording plates corresponding to the number of coupled spectral ranges is provided. In other words: Each mounting plate enables the spatial distribution of a parameter, for example a combustion radical or the temperature, to be determined. In addition, several mounting plates can determine the distribution of a parameter. Such an arrangement then corresponds to a multi-channel arrangement, this being required in particular in the case of high security requirements.

For the spatial resolution of the intensities or concentrations of the parameter to be examined, a “charge-coupled device camera” is expediently provided as the recording plate. This CCD camera, also called an optical image sensor, records the light emitted by the flame or the radiation spectrum of the flame. Due to the beam splitter connected upstream of the CCD camera, only the band radiation of the parameter to be examined ultimately reaches the CCD camera. From the spatially resolved intensities of the image of the CCD camera, the spatial distribution of the parameter, e.g. Concentration distribution of a combustion radical or the spatial distribution of the temperature in the flame can be determined. In addition to the detection of temperature and / or concentration distribution, the geometry of the flame can advantageously also be determined at the same time.

According to an expedient development, the device comprises an evaluation unit which is connected to the or each mounting plate. The evaluation unit, for example a personal computer, uses the spatially resolved intensities of the image of the CCD camera to determine an at least two-dimensional concentration distribution of a combustion radical to be examined or the temperature distribution in the flame. With other In other words, different areas of the mounting plate deliver independent signals and thus characterize different areas of the flame or the combustion chamber.

In addition, the current flow distribution within the flame is recorded on the basis of the flame image and analyzed in the evaluation unit. By evaluating several image sequences, for example, the degree of turbulence and the transport of various chemical substances within the flame are analyzed.

With regard to the device for flame analysis and flame monitoring, the above object is achieved with an optical system that generates a spatially resolved image of a flame on a mounting plate, and with a measuring module for measuring pulsating radiation parameters of the flame, with at least one beam splitter for coupling out at least one for one Examining parameters specific spectral range provided from the radiation spectrum of the flame and the beam splitter upstream of the receiving plate and the measuring module.

With the integration of the measuring module, in particular a flame sensor or detector in the optical system, flame monitoring is guaranteed at the same time as the combustion and flame analysis. Such a construction of the optical system - optical camera and flame monitor - is also particularly cost-effective and space-saving, since on the one hand only a suitable opening has to be provided in the wall of the combustion chamber. On the other hand, it is sufficient to use only one cooling system for cooling the cameras and one rinsing system for cleaning the surfaces of the optical arrangement, in particular the lens, per optical system. The advantages achieved by the invention consist in particular in that by recording the emission spectrum from a combustion process, in particular by recording emission spectra of individual flames, a spatial temperature distribution and / or spatial concentration profiles of reaction products in individual flames and in the entire combustion chamber are reconstructed by computer tomography and are displayed in the form of measuring fields. These measurement or data fields are particularly well suited for quick and reliable combustion analysis. In particular, by means of the special features which can be derived or derived from the measuring fields, such as, for example, the position of maxima or the shape of the distribution and their spatial change, setpoints for the fuel or air supply to individual burners can be determined. Such a control intervention directly at the place where pollutants are generated results in a particularly low pollutant emission.

In addition, due to the high local resolution and the simultaneous acquisition of the entire flame image, the combustion process is quantitatively recorded within a few milliseconds. Such a particularly rapid quantitative detection of the combustion process thus also enables particularly precise firing control of fast processes.

Embodiments of the invention are explained in more detail with reference to a drawing.

In it show:

1 shows a schematic representation of a device for combustion analysis in a combustion chamber,

2 shows a detail II from FIG. 1 on a larger scale with an optical system of the device, 3 shows a screen control field, the screen control field comprising an exemplary compilation of flame images of a flame image-parameter assignment consisting of four parameters,

4 shows a further screen control field, the evaluation of individual flame images for an overall flame image for the combustion chamber being shown as an example, and

5 shows a schematic representation of a device for flame analysis and flame monitoring in a combustion chamber.

Corresponding parts are provided with the same reference symbols in all figures.

FIG. 1 schematically shows a device 2 for combustion analysis in a combustion chamber 1.

In the fire or combustion chamber 1 of a steam generator system, not shown, e.g. a fossil-fired steam generator of a power plant or a waste incineration plant, the combustion process takes place. The device 2 comprises an optical system 10 and a data processing system 12 connected to the optical system 10. The optical system 10 captures radiation data D in the form of images via an opening 11 in the wall 13 of the combustion chamber 1 and guides this to the data - Processing system 12 too.

The optical system 10 is positioned on the wall 13 in this way by means of fastening means (not shown in detail), so that the largest possible field of vision, ie a large viewing angle α, results in at least one flame F arising in combustion chamber 1.

The optical system 10 comprises a lens 14 as an objective, with the lens 14 being followed by a number of beam splitters T1 to T3. The optical system 10 can also include a plurality of lenses 14 as an objective. The radiation emanating from the flame F of a burner 16 passes through the lens 14 in an imaging beam path, so that bundle beams 18 fall onto the beam splitter T1. The bundle beams 18 have the emission lines or band radiation of the reaction products formed during the combustion.

The beam splitter Tl and the beam splitters T2 and T3 connected downstream divide the beam 18 or the beam spectrum of the flame F into a number of spectral ranges 20 by physical beam splitting. The beam cross section remains unchanged, ie the beam beams 18 are divided evenly over the beam entire cross section of the beam splitters Tl, T2, T3 according to their chosen reflectance and transmittance. The beam splitters T1, T2, T3, also called line or narrow-band filters, thus enable a wavelength-dependent physical division of the bundle beams 18 into a number of spectral ranges 20. A further comparison is achieved by a number of correction filters 22, which are arranged directly in front of receiving plates 24 .

Each spectral range 20 filtered out of the radiation spectrum of the flame F is in each case imaged on an associated receiving plate 24. CCD image sensors with a spectral sensitivity of approx. 300 nm to approx. 1,000 n are used in particular as mounting plates 24, so that the entire visible radiation spectrum of the flame F can be detected without problems. Construction and working principle of such a CCD Image sensors are from the publication "Semiconductor Optoelectronics" by Maximilian Bleicher, 1986, Dr. A. Hüthig Verlag, Heidelberg, known. In the exemplary embodiment, three parameters (the concentrations of NO _x , CO and the temperature) are to be analyzed. Correspondingly, four mounting plates 24 are provided, each of which has a two-dimensional image of the combustion chamber 1 with the flame F. Correspondingly, four sets of radiation data D are read out from the sensors by the data processing system 12 and each processed into a computer tomographic reconstruction of the distribution of the temperature and of the reaction products arising during the combustion, which are used for a screen display and / or further processing to actual values for the control of the system suitable is.

FIG. 2 shows the basic structure of the optical system 10. The optical system 10 comprises a housing 26 with a cylindrical attachment 27 and with four mounting plates 24 ₃ , 24 ₄ , 24 ₅ , 24 ₆ arranged spatially separated from one another therein. To supply power to the mounting plates 24 ₃ to 24 _6, the optical system 10 comprises a power supply 29.

A correction filter 22 ₃ to 22 _{6 is} arranged in front of each mounting plate 24 ₃ to 24 ₆ . Depending on the spectral ranges 20 ₃ to 20 _{6 to be} coupled out from the radiation spectrum of the flame F, further correction filters 22 can be provided. The beam splitters Ti to T _{3 are connected} upstream of the correction filters 22 ₃ to 22 ₆ , the beam splitters T1 to T3 being inclined such that the mounting plates 24 ₃ to 24 ₆ are arranged at an angle of 90 ° to one another.

Due to the use of the optical system 10 directly on the combustion chamber 1, the optical system 10 comprises a cooling system 28. For each mounting plate 24 ₃ to 24 ₆ comprises the cooling system 28 has a cooling element 30, for example a Peltier element with a heat sink. In addition, the cooling system 28 comprises an insulation 32, in particular insulation wool, arranged on the inner wall of the housing 26.

To protect against contamination, the mounting plates 24 ₃ to 24 ₆ and the optical components, in particular the beam splitters T1 to T3, the correction filters 22 ₃ to 22 ₆ and the lens 14, and the cooling elements 30 are surrounded by a chamber 34 or capsule. For example, the chamber 34 is designed in the form of a sheet metal box with a cylindrical connection piece 35 arranged on one side surface. The housing 26 is essentially adapted to the shape of the chamber 34, the cap 27 of the housing 26 being inserted into the opening 11 of the wall 13 of the combustion chamber 1.

When operating the optical system 10, the parameters characteristic of the combustion, such as the reaction products of the combustion CO, CN and NO _x, as well as the temperature, are preprocessed. The flame F of the burner 16 is detected by means of the optical system 10. Depending on the positioning and viewing angle α of the optical system 10, this can also detect several flames F of several burners 16 simultaneously. In other words: When the optical system 10 is positioned at an angle of 90 ° to burners 16 arranged one above the other in a line, the optical system 10 can display one or more flames F-resolved in an image with a very large viewing window α.

The bundle beams 18 of the flame F are radiated onto the beam splitter T1 via the lens 14. The beam splitter T1, in particular a yellow filter, transmits a first spectral range 20ι greater than 545 nm (yellow light) and reflects a second spectral range 20 ₂ less than 500 nm (blue light). Then using the beam splitter T2, in particular a red filter, which splits the spectral range 20ι impinging on it into two further spectral ranges 20 ₃ and 20 ₄ , the spectral range 20 ₃ reflecting less than 630 nm (orange light) and the spectral range 20 transmitting greater than 630 nm (red light) becomes. In the two spectral ranges 20 ₃ and 20 ₄ is the so-called black or Gray body radiation according to the Planck 'provide law that serves to determine the temperature distribution of the flame F.

The beam splitter T3 divides the spectral range 20 ₂ coupled out by the beam splitter T1 with a bandwidth of less than 500 nm into a further spectral range 20 ₅ with a bandwidth of less than 400 nm (violet light) and a spectral range 20 ₆ with a

Bandwidth from 400 nm to 500 nm (green light). The emission line of the reaction product of the combustion CN is in the spectral range 20 ₅ and the emission line of the reaction product CO is in the spectral range 20 ₆ .

All light-deflecting or dividing optical components can be used as beam splitters Tl to T3, e.g. Color filters, prisms or mirrors. The beam splitters T1 to T3 used in the optical system 10 are so-called dichroic additive and subtractive color filters, which reflect the spectral range for a predeterminable bandwidth and also transmit the spectral range for a second bandwidth. The division and filtering of the spectral ranges can also be carried out by aperture division and appropriate filtering.

The spectral ranges 20 ₃ and 20 ₄ or 20 ₅ and 20 ₆ filtered out by the beam splitters T2 and T3 are limited to a bandwidth of approximately 10 nm by means of the correction filters 22 ₃ and 22 ₄ or 22 ₅ and 22 ₆ . That is, the correction filter 22 ₃ and 22 ₄ transmit a bandwidth from 545 to 555 nm or from 645 nm to 655 nm from the spectral ranges 20 ₃ and 20 _4. Analogously, the correction filters 22 ₅ and 22 ₆ transmit a bandwidth from the spectral ranges 20 ₅ and 20 ₆ 375 to 385 nm or from 445 to 455 nm. In particular, interference filters with a bandwidth of 10 nm +/- 2 nm are used as correction filters 22 ₃ to 22 ₆ .

The intensities or the light of the spectral ranges 20 ₃ to 20 ₆ filtered out in each case are recorded by the corresponding receiving plates 24 ₃ to 24 ₆ . The spatial distribution of the respective parameter, for example the temperature, the concentration of CO and CN, is then determined in the data processing system 12 by means of the voltage values or radiation data D of the receiving plates 24 ₃ to 24 ₆ resulting from the spatially resolved intensities of the images.

In order to prevent noise in the image picked up by the mounting plate 24 ₃ to 24 ₆ , the operating temperature of the mounting plate 24 ₃ to 24 _{6 must be kept} below an operating temperature of approximately 40.degree. For this purpose, the optical system 10 comprises a temperature sensor 36, for example a thermistor or a thermal switch, the measured value of which is fed to a fan 38. The supply of cooling air KL is controlled via the fan 38. A filter 39 for cleaning the cooling air KL is connected upstream of the fan 38.

The number of mounting plates 24 arranged in the optical system 10 is adapted to the number of parameters to be examined for the combustion process. It is usually sufficient to record the concentration distribution of the reaction products CO, NO as well as the temperature distribution and the geometry of the flame. (For example, an analysis of the oxygen concentration can also be revealing his) . Only in special cases are more than four mounting plates 24 required.

A screen control field 40 is shown as an example in FIG. This screen control field 40 comprises six output fields F1 to F6, a message window Ml and a number of input elements El to En. In the message window Ml, for example, status messages can be read from each burner 16 using color codes. By clicking on the letter "U", the operating personnel receive further information about a lower (corresponds to "U") burner 16, this burner 16 being arranged in the lower region of the combustion chamber 1.

The geometry of the flame, in particular its brightness, of a burner 16 is shown in the form of an image B1 in the output field F1. Analogous to the output field F1 in the output fields F3, F4, F5 and F6 in the associated pictures B3, B4, B5 and B6 are the distribution of the temperature, the distribution of the concentration of CO, the distribution of the concentration of NO _x and the Distribution of the concentration of CN shown in the flame. The normalized and numerical values of brightness, temperature and the respective concentration are realized by suitable color signaling in the images B1, B3, B4, B5, B6.

Depending on the intensities of the respective parameters recorded by the receiving plates 24, the corresponding flame image B1, B3, B4, B5 and B6 changes the color in the representation. A scale S1, S3, S4, S5, S6 is assigned to each image B1, B3, B4, B5, B6. The respective numerical value of the brightness, the concentration or the temperature of the parameter to be examined can be determined on the scale S1, S3, S4, S5 or S6 on the basis of the color signaling. The output field F2 shows numerical values of further process parameters that are important for the combustion process, for example the process parameter performance. Of course, other exemplary embodiments of the screen control panel 40 according to the prior art are also possible. Depending on the number of parameters of the combustion process to be examined, fewer or more output fields F1 to F6 are possible.

On the basis of the flame images F1 to F6, it is possible for the operating personnel to recognize and identify, in addition to the geometry of the flame, quantitative statements about pollutant formation in the flame. In addition, owing to the short measuring times of the mounting plates 24 of approximately 5 s, the optical system 10 allows spatially differentiated, multidimensional ones

To make flame images Fl, F3, F4, F5, F6 available very quickly, the measurement signals on which these flame images Fl, F3, F4, F5, F6 are based also a fuzzy or neuro-fuzzy logic for determining setpoints for a furnace regulation can be supplied. Particularly through the quantitative determination of the concentration distribution of reaction products of the combustion as well as the temperature distribution and their use in a combustion control system, a particularly low pollutant emission of the combustion process is guaranteed.

A further screen control field 42 is shown in FIG. The image of a total flame in a combustion chamber 1 is shown in the display control field 42 as an example in the output field F8. The temperature distribution in the combustion chamber 1 can be determined on the basis of the color signaling of the scale S7. In the message windows M2 to M6 arranged next to the flame image F8, there are numerical values for the parameters that arise during combustion, such as, for example maximum temperature or the average emission of CO and NO _x , readable.

In addition, four control panels K1 to K4 are arranged around the output field F8. Each control panel K1 to K4 characterizes control elements for controlling six burners 16. That is, these control panels K1 to K4 enable the operating personnel to switch each individual burner 16 of the combustion chamber 1 on and off, as well as the fuel supply for each individual burner 16 to control. In each case three burners 16 are supplied with fuel by a coal mill (not shown).

In addition, the screen control field 42, like the screen control field 40, comprises further input fields El to En. With the input fields El to En it is possible for the operating personnel to call up or carry out further process information and process controls.

FIG. 5 schematically shows a device 2 'for flame analysis and flame monitoring, comprising an optical system 10' and a data processing system 12 '. In this case, instead of a receiving plate 24 ₂ of FIG. 1 used in the optical system 10, a measuring module 44, in particular a flame detector or detector, is arranged. Analogous to the optical system 10 in FIG. 1, the optical system 10 'comprises as a lens a lens 14' and a number of beam splitters T1 'to T3' which are connected downstream of the lens 14 '. The spectral ranges 20 ₃ ', 20 ₅ ', 20 ₆ 'filtered out from the radiation spectrum of the flame F and their intensities are recorded by the corresponding recording plates 24 ₃ ' 24 ₅ 'and 24 ₆ ', the spatially resolved intensities of the images of the recording plates 24 ₃ ', 24 ₅ ' and 24 ₆ 'the spatial distribution of the parameters to be examined is determined in the data processing system 12'. The spectral range 20 ₄ ′, for example a broadband remainder of the radiation spectrum of the flame F, is recorded by the measuring module 44. The measuring module 44 converts pulsating radiation parameters of the spectral range 20 ₄ 'of the flame F into an electrical signal S. The measuring module 44 comprises three independent channels K1, K2 and K3 for simultaneous detection of the pulsation frequency of the flame F of the burner 16 lying in the spectral range 20'.

The data processing system 12 'independently evaluates the signals S of the channels K1 to K3. If, for example, two channels K1 and K2 supply the signal S = "flame off", the safety shutdown of the burner 16 is triggered.

The multi-channel design of the measuring module 44 and the three mounting plates 24 ₃ ', 24 ₅ ', 24 ₆ 'ensure both a high level of security when monitoring the flame F of an individual burner 16 and an analysis of the flame F with respect to temperature and concentration distributions within the flame F. Furthermore, due to the integrated arrangement of the measuring module 44 and the mounting plates 24 ₃ ', 24 ₅ ', 24 ₆ 'in an individual optical system 10', an opening 11 in the wall 13 of the combustion chamber 1 is sufficient. so that assembly and system costs in relation to the introduction of suitable openings 11 into the wall 13 and in relation to suitable holders or in relation to the necessary number of cooling systems are reduced.

Due to the simple structure of the optical system 10, 10 'and the passive optical detection of the combustion parameters, ie no additional light sources are required, this optical system 10, 10' is particularly suitable for use in power plants. In particular, the optical system 10, 10 'is suitable due to the very fast determination of measured values in the combustion resulting reaction products for combustion analysis and combustion control. The possibility of recording individual flame images also allows control technology to intervene in the combustion process directly at the location where pollutants are generated.

Claims

claims

1. Method for combustion analysis in a combustion chamber (1), in which a radiation spectrum of a flame (F) is recorded in the combustion chamber (1), a plurality of spectral ranges (20 to 20 ₆ ) being coupled out by beam splitting of the radiation spectrum, with the aid of decoupled spectral ranges (20 ₃ , 20 ₄ , 20 ₅ , 20 ₆ ) for a number of parameters characterizing the combustion process, a corresponding image (B1, B3, B4, B5, B6) of the flame (F) is generated, and wherein the respective images (B1, B3, B4, B5, B6) each show a spatial distribution of the corresponding parameter by means of spatially resolved intensities.

2. The method according to claim 1, wherein the or each spectral range (20 ₃ , 20 ₄ , 20 ₅ , 20 ₆ ) is coupled out with a bandwidth of approximately 5 to 20 nm.

3. The method according to claim 1 or 2, wherein by means of an emission line lying in a first spectral range (20 ₅ , 20 ₆ ) and its intensity, the spatial concentration distribution of a combustion radical in the flame (F) is reconstructed by computer tomography.

4. The method according to any one of claims 1 to 3, wherein the spatial temperature distribution in the flame (F) is reconstructed by computer tomography by means of the Planck radiation lying in a second spectral range (20 ₃ , 20 ₄ ) and its intensity.

5. The method according to any one of claims 1 to 4, wherein a pulsating parameter of the flame (F) is monitored and a pulsation parameter is determined by means of a third spectral range (20 ₄ ').

6. Device for combustion analysis in a combustion chamber (1) with an optical system (10), which has an objective for recording a radiation spectrum of a flame (F) in the combustion chamber (1) and a plurality of beam splitters (Tl to T3) connected downstream of the objective ) for coupling out a plurality of spectral ranges (20ι to 20 ₆ ), a number of recording plates (24) corresponding to a number of parameters of the combustion process to be examined, each of which has a spatially resolved image (B1, B3, B4, B5, B6) generate the flame (F), the beam splitters (Tl to T3) are connected downstream.

7. The device according to claim 6, wherein a cooling system (28) for cooling the optical system (10) is provided.

8. The device according to claim 6 or 7, wherein the cooling system (28) for the or each receiving plate (24) each comprises a cooling element (30).

9. Device according to one of claims 6 to 8, wherein the or each beam splitter (Tl to T3) is dichroic.

10. Device according to one of claims 6 to 9, in which a number of spatially separated recording plates (24 ₃ to 24 ₆ ) corresponding to the number of coupled spectral ranges (20 ₃ to 20 ₆ ) are provided.

11. The device according to one of claims 6 to 10, wherein a charge-coupled device camera is used as the receiving plate (24).

12. The device according to one of claims 6 to 11, wherein the or each receiving plate (24) is preceded by a filter (22).

13. Device according to one of claims 6 to 12, wherein the or each mounting plate (24) is connected to an evaluation unit (12).

14. Device for flame analysis and flame monitoring of a burner (16) in a combustion chamber (1) with an optical system (10) which on a mounting plate (24 ₃ ', 24 ₅ ', 24 ₆ ') has a spatially resolved image (Bl , B3, B4, B5, B6) of a flame (F), and with a measuring module (44) for measuring pulsating radiation parameters of the flame (F), at least one beam splitter (Tl 'to T3') for coupling out at least one for one Parameters to be examined of specific spectral range (20 ₃ 'to 20 ₆ ') from the radiation spectrum of the flame (F) are provided, the beam splitter (Tl 'to T3') of the mounting plate (24 ₃ ', 24 ₅ ', 24 ₆ ') and upstream of the measuring module (44).