RU2137047C1 - Flame remote monitoring device - Google Patents

Abstract

FIELD: thermal power stations and boiler units burning gaseous and liquid fuels; environment pollution control. SUBSTANCE: device has projection unit, flame radiation spectral component separation unit, and photodetector unit, as well as conversion and man- computer communication unit. Mounted in flame radiation spectral component separation unit is movable multiple-slot spectral filter whose displacement distance ensures alignment of lower boundary of transparent slot of movable filter on short wavelength side with upper boundary transparent slot of fixed filter as well as alignment of upper boundary of transparent slot of movable filter with lower boundary of transparent slot of fixed filter; in addition, movable filter is coupled with displacement unit which is connected through matching amplifier and digital-to-analog converter to conversion and man-computer communication unit. EFFECT: enlarged functional capabilities and improved reliability of selective flame monitoring. 1 cl, 3 dwg

Description

 The device relates to a power system, and in particular to devices for automatic control of the flame of burners of various heat generating units, and can be used in thermal power plants and boiler plants operating on gaseous and liquid fuels, as well as in the field of environmental monitoring.

 A device [1] for controlling a flame is known, comprising a projection device, a beam splitter separating the radiation beam coming from the flame into two separate beams, and two radiation receivers. The first receiver detects the infrared components of one beam, and the second receiver detects the UV components of another beam. The receivers can transmit an analog signal characterizing the flicker frequency of the IR component and a digital signal characterizing the total energy of the UV component to the processor. The processor decides on the state of the flame.

 The disadvantage of this device is the low reliability of the selective control of the torch of one burner device in case of simultaneous operation of several burners due to the unstable position of the sighting point of the control device, depending on the effect of torches of neighboring burners. In addition, this device cannot be used for simultaneous selective control of the torches of several burners, since the use of two single photodetectors does not provide the separation of information from several burner devices.

 Also known is a method and device for detecting flame control [2]. The method includes recording flame radiation in two fixed ranges and measuring the intensity ratio in these ranges. The device comprises a projection unit, a unit for isolating the spectral components of the flame radiation, a photodetector unit, display and ignition comparison units. The unit for isolating the spectral components of the flame radiation is made in the form of a dichroic beam splitter, and the photodetector unit includes two single photodiodes. In the device under consideration, the ratio of the intensities of the radiation of the wavelength in the range 470 - 530 nm and a wavelength of about 670 nm is measured. The value of this ratio from 0.1 to 1.0 means the presence of flame; if the ratio is outside these limits, there is no flame, and a signal is supplied to the ignition unit.

 The disadvantage of this device is the inability to selectively control several burners at the same time due to the use of single photodetectors, which record the total flame intensity in certain spectral ranges. Against the background of a strong signal from a common flame, selective control of a single torch will be unreliable. In addition, when using single photodetectors, it is not possible to analyze the spatial distribution of flame parameters, which can increase the reliability of the selective control of torch torches. In the considered device, information is recorded only in two spectral ranges, while the spectral composition of flame radiation during the combustion of hydrocarbon fuels has a larger number of characteristic spectral ranges, the simultaneous operation of which also increases the reliability of control.

 The closest to the proposed device for the combination of essential features and the problem to be solved is a flame monitoring device [3], which provides registration of flame radiation in several spectral ranges. The device comprises a projection unit, a unit for extracting spectral components of flame radiation, a photodetector unit, and a computer conversion and communication unit. The unit for isolating the spectral components of flame radiation is made up of a dispersing element sequentially located on the optical axis, a telescopic system with a multi-slot spectral filter and a multi-channel deflecting element, and the photodetector unit contains a linear multi-element photodetector. In the device under consideration, the ratio of the radiation intensities is measured in a number of short-wavelength spectral ranges (400 - 600 nm) and in the red region (about 670 nm). The device provides a selective determination of the operating modes of each burner of the power unit (operation of the ignition device, unsteady combustion, stationary combustion, lack of flame).

 The disadvantage of this device is the insufficiently high reliability of the selective control of burner operating modes and the inability to determine the efficiency of fuel combustion (underburning / burnout), since the radiation intensities in the short-wave spectral ranges are normalized to the radiation intensity in the red region, which in turn is determined not only by the mode combustion, but also by such parameters as the composition of the gas fuel, air humidity and the degree of mixing of the gas-air mixture, while olzovanie as reference radiation intensity values immediately adjacent radicals emission lines can improve reliability selective control modes of operation and implement the burners determining fuel efficiency [4].

 The inventive flame control device provides an extension of the functionality of the device and an increase in the reliability of selective flame control.

 The proposed device comprises a projection unit sequentially located on the optical axis, a unit for isolating the spectral components of the flame radiation and a photodetector unit, as well as a conversion and communication unit with an electronic computer. In the block for isolating the spectral components of the flame radiation, a movable multi-slit spectral filter is installed parallel to the stationary multi-slit spectral filter, and the range of movement of the moving filter ensures that the lower boundary (on the short wavelength side) of the transparent slit of the movable filter is combined with the upper boundary of the transparent slit of the fixed filter and the upper boundary of the transparent slit a movable filter with a lower boundary of the transparent slit of the fixed filter, in addition, the movable filter is connected to a moving unit which is connected via a matching amplifier and a digital to analog converter to convert unit and an electronic computing machine.

 New features are: the introduction of a movable multi-slot spectral filter in parallel with the stationary multi-slit spectral filter in the block for isolating the spectral components of flame radiation, and in addition, the movable filter is connected to a displacement unit, which is connected via a matching amplifier and digital-to-analog converter to the conversion and communication unit with an electronic computer by car.

 In FIG. 1, a, b shows a schematic representation of the proposed device for selective flame control (1, a is a side view, 1, b is a top view; here the displacement unit, matching amplifier, digital-to-analog converter, and computer conversion and communication unit are not shown.

 The proposed device consists of sequentially located on the same optical axis of the projection unit 1, the unit for extracting the spectral components of the radiation of the flame 2, the photodetector unit 3. The conversion and communication unit 4 is connected to the output of the photodetector unit 3. In turn, the unit for isolating the spectral components of the radiation of flame 2 consists of sequentially located on the optical axis of the dispersing element 5 and a telescopic system 6 with a movable 7 and a fixed 8 spectral filters and a multi-channel deflecting element 9 installed in the focus plane of the illuminating beam by the first lens of the telescopic system 6. Moreover, the spectral filters 7 and 8 are made in the form of M slots, the multi-channel deflecting element 9 consists of M sections, respectively, and the mobile spectrum The filter 7 is connected to the displacement assembly 10, which is connected through a matching amplifier 11 and a digital-to-analog converter 12 to the conversion and communication unit 4 of the computer. The photodetector unit 3 includes a linear multi-element photodetector (LMF) 13, the line of photosensitive elements of which is located in the focal plane of the second lens of the telescopic system 6 parallel to the rows of filter slots 7 and 8.

 The proposed device operates as follows. The image of the row N of burners 14 by the projection unit 1 is displayed on the plane of the dispersing element 5 of the unit 2 for separating the spectral components of the flame radiation, at which the light beams are deflected at different angles depending on the radiation wavelength. As the dispersing element 5, for example, a diffraction grating or a prism can be used. The telescopic system 6 projectively conjugates the plane of the dispersing element 5 and the receiving plane of the LMF 13. The first lens of the telescopic system 6 of unit 2 performs the Fourier transform of the input image, so that the light distribution in the focus plane of the illuminating beam by the first lens of the telescopic system 6 is a composition of shifted friend relative to each other (depending on the radiation wavelength) and spatial Fourier spectra located parallel to the series of burners The image torch burners.

 As recent studies have shown [4], it is possible to increase the reliability of the selective control of burner operating modes and determine the efficiency of fuel combustion by using radiation intensities in the spectral regions directly near the radiation bands as reference values. However, this approach requires almost doubling the number of channels, which in turn leads to a loss of spatial resolution. In order to create reference channels without loss of spatial resolution, an additional movable filter is introduced in the proposed device, and the reading is carried out in two cycles: first, the radiation intensity of the radicals is determined, then the movable filter is shifted and the radiation intensities in the spectral bands near the radiation bands of the radicals are determined. This approach additionally provides the possibility of operational coordination of radiation intensities in the spectral bands of the radiation of radicals and the reference spectral bands by changing the range of movement of the moving filter.

To implement this, spectral filters 7 and 8 are made as follows. Fixed 7 and moving 8 spectral filters have M slots, where M is the number of radical emission bands analyzed. The dimensions of the slits d _m ^{st of the} stationary spectral filter 8 are selected from those considerations that they let the spectral band of radiation pass from the radiation border of a specific radical (CH or C ₂ ) with capture of a several times larger range in the opposite direction to the end of the reference radiation band (for example, the long-wavelength boundary of the radiation of the radical towards shorter waves to the short-wavelength boundary of the reference radiation band).

d $\genfrac{}{}{0ex}{}{\text{st}}{\text{m}}$ = D • Δλ _m / (λ _max -λ _min ),
where D is the total filter aperture, m is the number of the spectral band corresponding to the radiation of a specific radical, Δλ _m is the total width of the m-th spectral band of radiation (from the long-wavelength border of the radiation of the radical to the short-wavelength border of the reference radiation band) λ _max and λ _min are the maximum and minimum radiation wavelengths.

The dimensions of the slots d _m ^{0 of the} movable filter are determined by the widths of the spectral bands of the reference signals
d $\genfrac{}{}{0ex}{}{\text{0}}{\text{m}}$ ≥ D • Δλ $\genfrac{}{}{0ex}{}{\text{0}}{\text{m}}$ / (λ _max -λ _min ),
where Δλ $\genfrac{}{}{0ex}{}{\text{0}}{\text{m}}$ - the width of the m-th spectral band of the reference signal. The relative position of the movable 7 and the stationary 8 filters is shown in FIG. 2.

First, from the computer, through a digital-to-analog converter 12, a matching amplifier 11, a control signal is supplied to the displacement unit 10, by which the movable filter is set so that the distance from the lower boundaries of its transparent slots (from the side of short wavelengths) to the upper boundaries of the transparent slots of the stationary the filter was d _m ¹ , where d _m ¹ is determined from the ratio
d $\genfrac{}{}{0ex}{}{\text{1}}{\text{m}}$ = D • Δλ $\genfrac{}{}{0ex}{}{\text{1}}{\text{m}}$ / (λ _max -λ _min ),
and Δλ $\genfrac{}{}{0ex}{}{\text{1}}{\text{m}}$ - the width of the mth selected spectral band of the radical study. The value of d _m ¹ is determined by the digital signal given from the computer through the conversion and communication unit 4 and converted into an analog signal using a digital-to-analog converter 12. The matching amplifier 11 provides the necessary signal level for controlling the displacement unit 10. Changing the value of d _m ¹ leads to a change in the width of the emitted spectral bands of the radiation of radicals, which, in turn, provides operational control of the level of light energy at the output of the spectral filters.

The light beams passing through the slots of the spectral filters 7 and 8 are deflected by the multi-channel deflecting element 9 of block 2 and transmitted to the plane of the LMF 13 of the photodetector block 3 by means of a second lens of the telescopic system 6. The multi-channel deflecting element 9 can be made of a set of successive triangular prisms with different angle at the apex. As the LMF 13, a photodiode array operating in the signal accumulation mode, FUK1L2, can be used [5]. The magnification coefficient k of the telescopic system 6 is determined by
k = L / m • l,
where L is the length of the LMF 13, m is the number of slots of the spectral filters 7 and 8, and l is the image size of the horizontal row of burners 14 in the input plane of the telescopic system 6. The deflection angles of the multichannel deflecting element 9 are selected from such a calculation that in each subsequent image channel the burners in the plane of the LMF 13 in the horizontal direction were shifted by L / M equal to the size of this image. For this, the deviation angle of the mth element is chosen equal to
α = arctan [L (M-2m + 1) / 2 • M • f],
where m = 1,2, ... M.

 In a different coordinate, the image of the burners from the plane of the dispersing element 6 is also transferred by the telescopic system to the plane of the LMF 13 (Fig. 1, b). The LMF 13 integrates the incident light flux in the direction perpendicular to the direction of the row of burners 14, for which a photodetector with elements extended along this direction is used. Additional integration can be performed by using a focon or anamorphic optics as part of the photodetector unit 3, which integrates light beams in the direction perpendicular to the row of burners 14 (by analogy with [3]).

 After registering the light distribution on the LMF 13, it is read. In block 4 of the conversion and communication with the computer, the output signal from the photodetector block 3 is converted from analog to digital and transmitted to the computer.

After the data have been entered and stored in a computer, the movable spectral filter is shifted in the direction perpendicular to the orientation of the slots by d _units , which is determined on the one hand from the condition d _units ≥ d _max ⁰ , where d _max ⁰ is the slot width corresponding to the maximum size of the reference radiation band Δλ $\genfrac{}{}{0ex}{}{\text{0}}{\text{max}}$ (which provides shielding of the spectral bands of the radiation of radicals), and on the other hand, the required value of the reference signal (for complete transmission of the reference spectral bands of the study, this value will be (d _m ^st -d _m ¹ ) _min , and with a further shift, the values of the reference signals decrease). Thus, by changing the magnitude of the shift in one or the other direction, the ratio of the intensities of the spectral bands of radicals and the reference spectral bands is adjusted. With parameter values λ _max = 0.9 μm, λ _min = 0.4 μm, D = 20 mm, Δλ $\genfrac{}{}{0ex}{}{\text{0}}{\text{max}}$ ≅ 50 nm and Δλ _cf ≅ 10 nm (where Δλ _cf is the average width of the radical emission band) the filter shift will be 1 - 2 mm. After registering the light distribution on the LMF 13, it is read and data is input into the computer similarly to the first clock cycle, after which the movable spectral filter 7 returns to its original position and the process is repeated.

 The light distribution read by a linear multi-element photodetector for subsequent data input into a computer is M one-dimensional images of a number of burners in M spectral ranges. After two read cycles, images of a series of burners are recorded in the computer memory in the M spectral ranges corresponding to the radiations of the radicals and in the M spectral ranges adjacent to the ranges of the radiations of the radicals. Further processing of damaged signals can be performed in a computer in various ways.

где i = 1, 2 - номер такта (1 соответствует считыванию излучения радикалов, 2 - считыванию опорных сигналов), n - номер горелки, m - номер спектрального диапазона, J - количество элементов фотоприемника на одну горелку, j - номер элемента фотоприемника внутри каждого спектрального диапазона (j ∈ [I,J]). Далее вычисляются разности суммарных сигналов для излучения каждого радикала и его окрестности для каждой горелки (т.е. определяется непосредственно вклад неравновесного излучения радикалов): a_m ⁿ = I_m ^n,1 - I_m ^n,2. Эта операция может выполняться как по всем спектральным диапазонам, так и по некоторой их выборке. Далее вычисляется отношение полученных разностей к опорным сигналам (интенсивность неравновесного излучения радикалов нормируется на величину фоновых сигналов): b_m ⁿ = a_m ⁿ/I_m ^n,2
и полученные коэффициенты сравниваются с допустимыми значениями (b_m ⁿ _min, b_m ⁿ _max), хранящимися в памяти ЭВМ. В случае, если эти коэффициенты превышают диапазон допустимых значений, горение идет с избытком воздуха и следует указание убавить подачу воздуха. В случае, если эти коэффициенты ниже диапазона допустимых значений, горение идет с недостатком воздуха и следует указание увеличить подачу воздуха.A block diagram of one of the possible algorithms for processing information in a computer is shown in FIG. 3. Within each spectral range, the summation of the signals from the photodetector elements corresponding to one burner is carried out, the total signals are calculated

where i = 1, 2 is the cycle number (1 corresponds to the reading of the radiation of radicals, 2 to the reading of the reference signals), n is the number of the burner, m is the number of the spectral range, J is the number of photodetector elements per burner, j is the number of the photodetector element inside each spectral range (j ∈ [I, J]). Next, the differences of the total signals for the radiation of each radical and its surroundings for each burner are calculated (i.e., the contribution of the nonequilibrium radiation of the radicals is determined directly): a _m ⁿ = I _m ^{n, 1} - I _m ^{n, 2} . This operation can be performed both over all spectral ranges and over some of their samples. Next, the ratio of the differences obtained to the reference signals is calculated (the intensity of the nonequilibrium radiation of the radicals is normalized to the value of the background signals): b _m ⁿ = a _m ⁿ / I _m ^{n, 2}
and the obtained coefficients are compared with acceptable values (b _m ⁿ _min , b _m ⁿ _max ) stored in the computer memory. In the event that these coefficients exceed the range of permissible values, combustion is carried out with excess air and an indication should be given to reduce the air supply. If these coefficients are below the range of acceptable values, the combustion occurs with a lack of air and an indication should be given to increase the air supply.

 The photodetector unit 3 can be performed, for example, by analogy with [3].

 The conversion and communication unit 4 can be implemented as part of one of the standard interfaces that provide programmatic information exchange with computers using standard exchange protocols [6], [7]. An example of the technical implementation of block 4 conversion and communication with a computer is given in [8].

 As a digital-to-analog Converter 11, you can use the chip KM 1118 PA2 [9].

 As a matching amplifier, for example, one can use the amplifier presented in [10].

 As a displacement unit, a direct current solenoid with a retracting armature can be used [11].

Literature
1. UK patent 2188416, G 01 J 5/10, G 08 B 17/12.

 2. French patent 2654509, G 01 J 5/60.

 3. Patent of Russia 2072480, F 23 N 5/08.

 4. Antsygin V.D., Borzov S.M., Potaturkin O.I., Shushkov N.N. Transformation of the spectral properties of a hydrocarbon flame with a change in the combustion mode. // Autometry, 1997, N6, pp. 9-14.

 5. Multi-element photodetector FUK1L2. - Specifications TF3.974.061TU.

 6. Myachev A. A., Stepanov V. N., Scherbo V. K. Interfaces of data processing systems. Directory. - M.: Radio and Communications, 1989, pp. 56-67.

 7. Moricita I. Hardware microcomputers. - M.: Mir, 1988, pp. 172-194.

 8. Dorozhko Yu. A., Shpileva B.N., Schupak O.S., Yakushev A.K. Ten-digit ADC in the standard IBM PC. // Instruments and experimental technique, 1993, 1, p. 241.

 9. Martsinkevičius A.-J. K., Bagdanskis E.-A. K. and others. High-speed integrated circuits DAC and ADC and measurement of their parameters. - M .: Radio and communications, 1988, pp. 37 - 56.

 10. Danilov A. A. Powerful large-scale DC amplifier. // Instruments and experimental technique, 1988.6, p. 105.

 11. Emelyanov B. I., Emelyanov V. A. Executive devices of industrial regulators. - M.: Mechanical Engineering, 1975, pp. 120-129.

Claims (1)

 A remote flame control device comprising a projection unit and a unit for isolating the spectral components of flame radiation with a multi-slot spectral filter sequentially located along the optical axis, connected to a photodetector unit connected via a conversion and communication unit to an electronic computer, characterized in that in the spectral extraction unit of the components of the flame radiation parallel to the stationary multi-slit spectral filter, a movable multi-slit spectral filter is installed a filter, wherein the range of movement of the movable filter ensures that the lower boundary (on the short wavelength side) of the transparent slit of the movable filter is aligned with the upper boundary of the transparent slit of the fixed filter and the upper boundary of the transparent slit of the movable filter with the lower boundary of the transparent slit of the fixed filter, in addition, the movable filter is connected with a displacement unit, which is connected through a matching amplifier and a digital-to-analog converter to a conversion and communication unit with an electronic computer.

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