WO2007043913A1

WO2007043913A1 - Optoelectronic spectral gas analyser

Info

Publication number: WO2007043913A1
Application number: PCT/RU2006/000456
Authority: WO
Inventors: Nikolay Nikitich Konkov; Georgiy Urevich Ratis
Original assignee: Obshestvo S Ogranicennoi Otvetstvennostyu 'finstroi'
Priority date: 2005-10-11
Filing date: 2006-08-29
Publication date: 2007-04-19
Also published as: RU2299424C1

Abstract

The inventive optoelectronic spectral gas analyser relates to gas analysis engineering and can be used for determining qualitative and quantitative compositions of gas mixtures produced by the life activity of organisms or released by the operation of different devices and internal combustion engines and also for the quality inspection of perfumery products. Said optoelectronic spectral gas analyser makes it possible to produce and analyse emission spectra and comprises a power supply unit, lightening element, optical cell, input beam fast shutter, output beam fast shutter, element for spectrally decomposing an analysable signal, sensor unit, multi-channel amplifier, analog-to-digital converter, control unit, digital-to-analog converter, light detector and an optical system. The lightening element, input beam fast shutter and the optical cell are position on one optical axis, whereas the optical cell, output beam fast shutter, element for spectrally decomposing an analysable signal and the sensor unit are positioned on another optical axis.

Description

OPTICAL ELECTRONIC SPECTRAL GAS ANALYZER

Technical field

Optoelectronic spectral gas analyzer refers to the technique of gas analysis and can be used to determine the qualitative and quantitative composition of gas mixtures formed as a result of the life of organisms or released during the operation of various devices, internal combustion engines, as well as for quality control of perfumes.

BACKGROUND OF THE INVENTION A technical solution is known according to the patent RU 2091764, IPC 6 G Ol

N 21/61 of 08.16.94, published 09.27.97, Bulletin JVk 27, “Optical Focal Point Analyzer)) (1). The invention relates to techniques for analytical and measuring instrumentation for the detection and determination of gas concentrations and can be used in coal, chemical, oil refining, gas and other industries. The device comprises sequentially mounted and optically coupled emitters, an input optical fiber, a multi-pass cell consisting of three spherical mirrors, an output optical fiber, an information recording and processing unit. A spectral integral demultiplexer is installed between the output optical fiber and the recording unit, and on the continuation of the collective mirror sphere in the immediate vicinity of its edge, the ends of the input and output optical fibers are installed on one side, both lens mirrors are mounted with the possibility of joint rotation relative to the center of curvature of the mirror collective in the common meridional plane of all mirrors.

The technical solution is also known according to patent RU 2083959, IPC 6G01 J 3/42, dated March 21, 1995, published July 10, 1997, bulletin JVb 19, “METHOD FOR MEASURING KOHT IEHTPA-CIIGAZOBMETODOMKOPPF WITHOUT HUMIDIFIER-KGJ £ KTPCCKO

The invention relates to methods for measuring gas concentrations in gaseous media by absorption spectroscopy, in particular, to methods for measuring gaseous impurities in the atmosphere and controlling environmental pollution. The method of correlation Fourier spectroscopy involves measuring the intensities of a specific set of Fourier spectrum components

SUBSTITUTE SHEET (RULE 26) received radiation, and the values of the Fourier variables of the measured Fourier components correlate with the positions of the maxima and minima in the Fourier spectrum of the absorption spectrum of the measured gas, and the received radiation is analyzed only in the wave number range, where the measured gas has absorption lines.

With this method, for noticeable absorption of radiation, it is necessary that the concentration of the desired substance be sufficiently high (at least 0.001%), which determines the relatively low sensitivity of the devices. The closest is the technical solution for the patent copyright certificate SU 1672814, IPC 6 G 01 N 21/31, dated 10/06/89, published on 05/20/96, Bulletin Na 14, "GAZOAHALIZATOP". (3)

The invention relates to techniques for gas analysis and can be used to determine the quantitative and qualitative composition of gas mixtures formed as a result of the activity of organisms or released during the operation of various devices, such as internal combustion engines.

This technical solution is aimed at expanding the functionality of the gas analyzer, by determining the qualitative composition of the gas mixture, and increasing the accuracy and sensitivity. In a gas analyzer containing a radiating diode, the pn junctions of which are identical in the same crystal, the focusing optical system with at least one element made in the form of a concave reflector with a photodetector in its focus, and an electronic circuit for extracting useful a signal connected to a photodetector, a diffraction grating is deposited on the surface of at least one of the reflectors, and / or the gas analyzer comprises a diffraction grating, in the meridional plane of which in the directions The main diffraction maxima are a diode and a photodetector. The diode is made in the form of a linear matrix with the number of elements N, determined by the condition with at least one element made in the form of a concave reflector with a photodetector in focus, and an electronic circuit for extracting a useful signal connected to the photodetector to the surface of at least one of reflectors, a diffraction grating is applied, and if the gas analyzer contains a diffraction grating, in the meridional plane of which, in the directions of the main diffraction maxima, there is a diode and a photodetector: Daod

SUBSTITUTE SHEET (RULE 26) made in the form of a linear matrix with the number of elements N, determined by the condition

and the light-emitting region of each element has a transverse dimension h, which for non-overlapping absorption bands of gases satisfies the condition

and in other cases it is determined from the condition

dх where IΛ is the dispersion of the lattice or system;

ΔA is the resolution of the grating or system;

Δλ, is the smallest of the half-widths of the characteristic absorption bands of the proposed gases;

^D Λ, is the half-width of the electroluminescence spectrum of the emitting diode; H is the distance between the centers of the matrix elements.

But this device does not allow real-time determination of the presence of the desired substance, if it is present in the gas, if its concentration is so low that it does not cause noticeable absorption of electromagnetic radiation of the returned wavelength, i.e. lies below the sensitivity threshold of the device

Disclosure of invention

The objective of the proposed technical solution is to create an oshiko-electronic spectral gas analyzer with advanced functionality and high resolution.

The problem is solved due to the fact that the optical-electronic spectral gas analyzer containing a lighting element,

SUBSTITUTE SHEET (RULE 26) connected to the output of the power supply unit, an optical cuvette, an element for forming a spectral decomposition of the analyzed signal, a photodetector and a control unit configured to process and output information, characterized in that a fast input beam photo-shutter, a fast output beam photo-shutter, an optical system are introduced into it, containing spectral windows for transmitting the analyzed signal to a photodetector made in the form of a block of detectors, a multi-channel amplifier, analog-digital and digital-to-analog conversion The shutters, while the shutters, the detector unit, and the multi-channel amplifier are connected to the output of the power supply, to the input of which the control unit is connected via the digital-to-analog converter, and the fast output beam photo-shutter, an element for generating the spectral decomposition of the analyzed signal, the optical system, the unit are connected to the optical cuvette detectors, multi-channel amplifier, analog-to-digital converter and control unit, lighting element, fast input beam photo-shutter and wholesale Ceska cell disposed on the same optical axis and the optical cell, the output beam fast shutter element to form the spectral decomposition of the analyzed signal, the optical system and the sensor unit are arranged on different optical axes.

Brief Description of the Drawings

The proposed block diagram of an optoelectronic spectral gas analyzer in which an element for forming the spectral decomposition of the analyzed signal is sequentially coupled is a fast output-beam shutter, an optical system containing spectral windows from 1 to ... p for transmitting the analyzed signal to a photodetector made in the form of a detector block output optical signal, containing from 1 to ... n detectors, which allows individually registering and converting the emitted optical signal into each Ohm, a predetermined spectral range, a multi-channel amplifier of electrical signals from a photodetector, an analog-to-digital converter (ADC), a control unit, for example, a computer, whose software includes a database of spectral characteristics of the analyzed substances and a pattern recognition program, and also a gas analyzer control program, allows you to create and

SUBSTITUTE SHEET (RULE 26) analyze emission spectra rather than absorption, as in existing analogs and prototypes.

Since the spectral lines of each substance have a certain width, it is impossible to simulate the wavelength and line width at the same time, unambiguous identification of substances is carried out with a very high degree of probability.

The ability to analyze the emission spectra recorded by the proposed device, rather than the absorption spectra, make it possible to detect the desired substances even in the case of negligible concentrations, when their number is measured in thousands of molecules, since modern PMTs can detect literally individual photons.

Using a computer with special software in the device allows analyzing the composition of the gas mixture in several seconds for several substances and the analysis can be carried out in real time.

The presence of an element for the formation of the spectral decomposition of the analyzed signal allows you to decompose the light pulse into the spectrum simultaneously with the focusing of the signal, which can significantly increase the resolution of the device. The gas analyzer of the described type has not too large dimensions and mass, and can be performed both in stationary and in portable form.

The drawing shows a block diagram of an optical-electronic spectral gas analyzer, where the power supply unit 1, the lighting element 2, the fast photo-shutter of the input beam 3, the optical cuvette 4, the device for purging the optical cuvette with cleaning gas 5, the device for letting the analyzed gas mixture into the optical cuvette 6, fast output beam photo-shutter 7, element for the formation of spectral decomposition of the analyzed signal 8, optical system 9, detector block Schmogokanapan-amplifier 11, analog-to-digital converter (ADC) 12, block control нш (БУ) 13, ishfpoanshorovzhpeob The best in the variant of the implementation of the invention

Olshko-elektronnaya spectral gas analyzer is made as follows. The output of the power supply 1 is connected: a lighting element 2, a fast photo-shutter of the input beam 3, a device for purging an optical cell with a cleaning gas 5, a device for analyzing the inlet

SUBSTITUTE SHEET (RULE 26) gas mixture into an optical cuvette 6, an element for forming the spectral decomposition of the analyzed signal 8, a detector unit 10, a multi-channel amplifier 11, and a control unit 13 is connected to the input through a digital-to-analog converter (DAC) 14. Lighting element 2, a fast photo-gate of the input beam 3, the cuvette 4 are located on one optical axis along which the incoming beam passes, and cuvette 4, a fast photo-shutter of the output beam 7, an element for forming the spectral decomposition of the analyzed signal 8, the optical system 9, block det The vectors 10 are located on another optical axis along which the outgoing beam propagates.

A fast photo-shutter of the output beam 7, an element for forming the spectral decomposition of the analyzed signal 8, an optical system 9, for transmitting the analyzed signal to the block of detectors 10 of the output optical signal (from 1 to ... p), allowing individually recording the emitted optical signal in each predetermined spectral range, a multi-channel amplifier 11, electrical signals from block 10, an analog-to-digital converter (ADC) 12, a control unit 13, for example p computer, which includes a database of spectral characteristics of the analyzed substances and a pattern recognition program, as well as a gas analyzer control program, a digital-to-analog converter (DAC) 14.

Optoelectronic spectral gas analyzer operates as follows. The operation of this device is based on the use of the duality principle (Yu.L. Ratis, 1984) for the numerical Fourier transform (see [4] - [6]). According to the duality principle, in the numerical or hardware integration of functions having sharp peaks (for example, spectral lines or bands in the radiation or absorption spectrum), it is necessary to consider the problem of recognizing the image (signal) both for the function itself and for its Fourier image since the delta -the peak in the coordinate space turns into a substrate function in the Fourier-conjugate space and vice versa, insofar as the simultaneous numerical or hardware analysis of both the function itself and its Fourier image allows is to minimize the error probability of identifying a substance for

SUBSTITUTE SHEET (RULE 26) by determining the qualitative composition of the gas mixture from the emission spectra, as well as increasing its accuracy and sensitivity.

The control unit 13 through the DAC 14 provides a control signal to the power supply 1 to turn on the device purge the optical cell 4 cleaning gas.

After the optical cuvette 4 has been set for purging time, the control unit 11 gives out control signals through the DAC 14 to the power supply unit 1, for switching on the analyzer gas inlet device 6 into the optical cuvette 4, for short-term switching on of a powerful illuminator 2 and a fast input shutter 3 lighting system.

As a result of pulsed illumination, some of the atoms and molecules that make up the analyzed gas mixture go into an excited state.

Upon deexcitation, these atoms and molecules emit electromagnetic radiation in the infrared, visible and, in some cases, in the ultraviolet range.

Simultaneously with closing the fast input shutter 3, the control unit 13 through the DAC 14, using the power supply 1, opens the fast output shutter 7. The element for generating the spectral decomposition of the analyzed signal 8 decomposes the light pulse formed in the optical cuvette 4 into a spectrum.

After that, through the optical system 9, light pulses in each spectral window enter the block of detectors 10. After the optoelectric conversion using the block of detectors 10, the electric signals from each channel (spectral range) are sent to the multi-channel amplifier 11, from which the signal through the ADC 12 enters to the control unit 13 for digital information processing.

The control unit 13 processes the input signal using an algorithm that uses the principle of duality, and sees information about the chemical composition of the gas mixture from each spectral window

The system of spectral windows is built taking into account the fact that many molecular compounds have sufficiently long-lived levels precisely in the optical and infrared ranges. For each spectral range

SUBSTITUTE SHEET (RULE 26) CO. ≤ GO ≤ CO. + ΔCO. the output signal is regastered by the detector, where CO is the cyclic frequency of the electromagic radiation emitted by the atoms and molecules of the substance located in the optical cell 4, CO. - the smallest cyclic frequency for the i-th

channel (spectral range), ΔCO. - width of the spectral window

- As a rule, they use a CCD line 9.

Let P be the number of speckle windows that coincides with the number of detectors. At the output of the block of detectors 10 we get a system of response functions (by the number of detectors n):

G) ₁ + A (D ₁

F ₁ (t, ω _t <oo <G) ₁ + AcO ₁ ) = J f _x (t, ω) dω ω,

ω _n + Δω _n u F _n (t, co _n <ω <ω _n + Δω _n ) = J f _n (t, ω) dω

(i)

Where

P is the number of spectral windows

^ i-sigalot of the i-th detector (1 ≤ 1 ≤ П) t-time.

15 By the type of functions ^ i (.Ц CO _j ≤ СО ≤ СО. + ΔCO _j ), the substances contained in the cell can be identified.

substance. Measured average lifetime ^ i "gpocc-level":

F _; (t, ω. <ω <ω. + Δω _i ) "C _i

(2)

^ v In this case, the device detects the presence of the desired substance, and estimates its concentration with sufficient accuracy for practical purposes.

SUBSTITUTE SHEET (RULE 26) BIBLIOGRAPHY

1. RU 2091764, IPC 6 G 01 N 21/61 of 08.16.94, publ. 09/27/97, bull. Ja 27, “Optical-optical analyzer)).

2. RU 2083959, IPC 6 G 01 J 3/42, dated 21.03.95, publ. 07/10/97, bull. JNe 19, “METHOD FOR MEASURING GAS CONCENTRATION BY METHOD

CORRELATION FURIE-SPECKTPOCKOPII "(2)

3. SU 1672814, IPC 6 G 01 N 21/31, dated 06.10.89, publ. 05/20/96, bull. Na 14, "GASOAHALIZATOP".

4. Yu.L. Ratis, M.L. Kalyaev Collective phenomena in heat-resistant coatings during thermal shock, Dep. VINITI, JN ° 6594-84, 10/08/1984,

5. Yu.L. Ratis, V.V. Joiner, Kalecki's generalized model for describing the economy of large cities, Market economy. State, problems, prospects, Department of Economics, Russian Academy of Sciences, MIR, Samara, 1998, 6 pp.

6. YuX. Ratis, G.I. Leopovish, A. Yu. Melpikov, Light fluff difrrástiop оf fibеr - ortisal apd ortisal eloptropis trapsducers оf mekhapisal displacempt, Рroseyepgs оf

SPIE, Volumé 3348, Computer Apd HoloGarhis Ortis Ap Imagé Process, 1997, p.336-343

SUBSTITUTE SHEET (RULE 26)

Claims

FORMULA

An optical-electronic spectral gas analyzer containing a lighting element connected to the output of the power supply unit, an optical cuvette, an element for forming a spectral decomposition of the analyzed signal, a photodetector and a control unit configured to process and output information, characterized in that a fast input photo-gate is introduced into it beam, fast shutter of the output beam, an optical system containing spectral windows for transmitting the analyzed signal to a photodetector made in the form of a block detectors, a multi-channel amplifier, analog-to-digital and digital-to-analog converters, with photo-gates, a detector block and a multi-channel amplifier connected to the output of the power supply, to the input of which a control unit is connected via a digital-to-analog converter, and a fast output beam photo-shutter, an element, are connected in series for the formation of the spectral decomposition of the analyzed signal, an optical system, a block of detectors, a multi-channel amplifier, analog-to-digital converter The control unit, the illumination element, the fast input beam shutter and the optical cell are located on the same optical axis, and the optical cell, the fast output beam shutter, the element for the spectral decomposition of the analyzed signal, the optical system and the detector block are located on the other optical axis.

SUBSTITUTE SHEET (RULE 26)