EP0503011A1 - Procede pour la determination de la concentration de substances, dispositif pour la mise en uvre de ce procede, application dudit procede pour faire varier la concentration d'une substance contenue dans un fluide et appareillage y relatif - Google Patents

Procede pour la determination de la concentration de substances, dispositif pour la mise en uvre de ce procede, application dudit procede pour faire varier la concentration d'une substance contenue dans un fluide et appareillage y relatif

Info

Publication number
EP0503011A1
EP0503011A1 EP19910914541 EP91914541A EP0503011A1 EP 0503011 A1 EP0503011 A1 EP 0503011A1 EP 19910914541 EP19910914541 EP 19910914541 EP 91914541 A EP91914541 A EP 91914541A EP 0503011 A1 EP0503011 A1 EP 0503011A1
Authority
EP
European Patent Office
Prior art keywords
concentration
radiation
frequency
substance
substances
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19910914541
Other languages
German (de)
English (en)
Inventor
Heinz Jürgen KAIBLINGER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chlean Plants and Engineering Ets
Original Assignee
Chlean Plants and Engineering Ets
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Chlean Plants and Engineering Ets filed Critical Chlean Plants and Engineering Ets
Publication of EP0503011A1 publication Critical patent/EP0503011A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/54—Nitrogen compounds
    • B01D53/56—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2882—Catalytic reactors combined or associated with other devices, e.g. exhaust silencers or other exhaust purification devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47—Scattering, i.e. diffuse reflection
    • G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
    • G01N21/53—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2250/00—Combinations of different methods of purification
    • F01N2250/02—Combinations of different methods of purification filtering and catalytic conversion
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J2001/4238—Pulsed light
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J2001/4242—Modulated light, e.g. for synchronizing source and detector circuit
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47—Scattering, i.e. diffuse reflection
    • G01N2021/4704—Angular selective
    • G01N2021/4709—Backscatter
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47—Scattering, i.e. diffuse reflection
    • G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
    • G01N21/53—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke
    • G01N21/534—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke by measuring transmission alone, i.e. determining opacity

Definitions

  • the invention relates to a method for measuring the concentration of substances according to the preamble of claim 1, a device for carrying out the method according to the preamble of claim 9, a system for changing the concentration of at least one substance contained in the fluid according to the preamble of claim 16 and an application the method for changing the concentration of at least one substance contained in the fluid according to the preamble of patent claim 19.
  • the intensity of the transmitted radiation depends on the medium, the substances mixed in with the medium and the frequency of the radiation.
  • An unknown substance in the medium can be identified from these frequency-dependent damping values adorned, or in the case of a known substance whose concentration in the medium can be determined.
  • a generic method for measuring the concentration of substances is known from DE-OS 25 25 375.
  • the light beam of a semiconductor diode with a tunable emission wavelength is sent through a measuring medium and detected.
  • the emission wavelength is periodically switched between the absorption maximum and an adjacent minimum. If the center frequency of the radiation emitted by the diode lies on the flank of the absorption line, an alternating signal is received by the detector, which is given to a phase-sensitive detector, the output signal of which is a direct measure of the concentration of the gas component in the measuring medium.
  • Another generic method for measuring the concentration of substances is known from DE-OS 37 41 026.
  • a laser is switched back and forth between two of its own resonance frequencies, one of the resonance frequencies being in the absorption maximum and the other resonance frequency in the absorption minimum of the gas to be detected.
  • the concentration of the gas to be examined is derived from the ratio of the intensity attenuation of the two resonance frequencies.
  • the value of the transmitted radiation intensity is stored in a sample + hold circuit.
  • the values stored in the sample + hold circuit are processed with a computer circuit every measuring cycle.
  • the present invention describes a new signal processing in which a concentration measurement of a substance contained in a measuring medium is carried out using at least two different radiation frequencies.
  • the methods shown, their use, and the device used to carry out the method are distinguished by a high level of signal interference immunity.
  • the object is further achieved to change the concentration of at least one substance contained in a fluid, i. H. in particular to reduce the pollutant content contained in the fluid. Examples of methods according to the invention, a device according to the invention, their use and a system for changing the concentration of at least one substance contained in a fluid are explained in more detail below with reference to drawings. Show it:
  • FIG. 1 shows a block diagram of a device for carrying out concentration measurements
  • FIG. 2 shows the temporal sequence of the pulsed radiation emitted by the transmitter of the device with the alternating radiation frequencies f 1 and f 2 ,
  • FIG. 3 shows a schematic representation of the temporal sequence of the radiation shown in FIG.
  • FIG. 4 shows a block diagram of the signal conditioning circuit of the device for concentration measurement
  • FIG. 5 shows a variant of the signal conditioning circuit shown in FIG. 4,
  • Fig. 6 shows an idealized representation of the time
  • FIG. 3 shows the pulse sequence shown after passing through a bandpass of the signal processing circuit
  • Fig. 7 shows an idealized representation of the time
  • FIG. 6 shows the pulse sequence shown after passing through an integrator with the discharge time constant of the signal processing circuit
  • FIG. 8 shows a low-frequency section of the frequency spectrum of the pulse sequence
  • FIG. 9 shows a block diagram of a device for reducing the pollutant content in the exhaust gases of a diesel engine.
  • the device for concentration measurement of substances in a measuring medium 1 shown in the block diagram in FIG. 1 has a transmitter 3, a plurality of measuring cuvettes 5a ... 5z, each containing a reference medium with known absorption for the radiation emitted by the transmitter 3 and known concentration a partially transparent mirror 7a ... 7z and each with a radiation detector 9a ... 9z, which converts the radiation falling on it in proportion to the intensity into an electrical signal, a further beam controller 11 which detects the output radiation of the transmitter 3 in the measuring medium 1 and to the measuring cuvettes 5a ...
  • a detector 13 which transmitted the intensity of the measuring medium 1 Converts radiation into an electrical signal and a detector 15, onto which a part of the radiation emitted by the transmitter 3 without having transmitted a reference cuvette 5a ... 5z or the measuring medium 1 falls.
  • Each of the detectors 9a ... 9z, 13 and 15 is connected via an electrical line 17a ... 17z, 19 and 20 to a signal conditioning circuit 21, 22 and 23, respectively.
  • the signal conditioning circuits 21, 22 and 23 are connected to an evaluation circuit 25 which determines the value of the concentration of the substance contained in the measuring medium 1.
  • the signal lines are shown in Figure 1 with solid lines and the paths of the rays with dashed lines.
  • the evaluation device 25 is connected to a power amplifier 26 with which data and setting values can be transmitted in order to reduce the pollutant content in the exhaust gases of an internal combustion engine, in particular a diesel engine 51, as described below in an example and in the block diagram in FIG .
  • Internal combustion engines are understood to mean motors which convert chemically bound energy into mechanically usable energy by means of combustion.
  • Known embodiments include diesel and gasoline engines, jet engines, gas turbines, etc.
  • the transmitter 3 is connected to a control device 27, which contains a power supply 29 and a driver 30.
  • the driver 30 is a time device which controls the energy supply 29 in such a way that the transmitter sends 3 pulses of different radiations with the frequencies f 1 and f 2 , with the same repetition frequency 1 / T N and constant pulse spacing T T to one another.
  • the pulse interval T T is understood as the time interval from the start of a pulse to the start of the following other pulse with the other radiation with the other radiation frequency.
  • the driver 30 is connected to the evaluation circuit 25 for the synchronization of the measured value processing.
  • the transmitter 3 transmits, as in Fi Shown gur 2, pulsed radiation with a pulse duration d with the radiation frequencies f 1 and f 2 .
  • the pulse spacing of pulses of the same radiation frequency f 1 or f 2 is T N.
  • the pulse interval T T of successive pulses has been chosen to be the same size and is half the pulse interval T N.
  • the switching frequency of all pulses is twice as high as the switching frequency of the pulses with a radiation frequency f 1 or f 2 .
  • Each pulse with the radiation frequency f 1 lies in the middle between two pulses with the radiation frequency f 2 . The same applies to the pulses of the radiation frequency f 2 .
  • the transmitter 3 emits a pulse with the pulse width d with radiation of the radiation frequency f 1 , which is in the range of the absorption maximum of the known substance.
  • the radiation f 1 hits the beam splitter 11 and is split here. Part of the radiation f 1 transmits the measuring medium 1, its intensity is measured with the detector 13 and the electrical measuring signal is passed on to the signal conditioning circuit 22. The other part of the radiation f 1 strikes the semitransparent mirror 7a, the other semitransparent mirrors ... 7z have been folded away and are split again here.
  • Part of the radiation f 1 radiates through the reference cuvette 5a.
  • the transmitted intensity is measured by the detector 9a and the electrical measurement signal is forwarded to the signal processing circuit 21.
  • the rest of the radiation f 1 strikes the detector 15 and is passed on to the signal conditioning circuit 23.
  • the transmitter 3 is switched and a pulse with the pulse width d with radiation of the beam tion frequency f 2 , which is not only weakly absorbed by the known material, is emitted analogously to the above method for the frequency f 1 .
  • the entire above process is repeated.
  • the transmitter 3 emits pulses with a constant and the same pulse repetition frequency 1 / T T and constant pulse height, alternating between a pulse with the radiation frequency f 1 and the following pulse with the radiation frequency f 2 .
  • the intensity of the pulses with the radiation frequency f 1 is weakened by the substance in the measuring medium 1 or in the reference cuvette 5a and the one with the radiation frequency f 2 is received by the detector 13 or 9a almost without attenuation.
  • the pulse train after leaving the transmitter 3, measured with the detector 15, is shown in FIG. 2.
  • the pulse train after passing through the measuring medium 1, measured with the detector 13, is shown in FIG.
  • the pulse trains transmitting the reference cuvette 5a and the measuring medium 1 are similar to one another.
  • FIG. 3 shows a typical, schematically illustrated pulse train, measured with the detector 13.
  • the pulse trains differ only in the absolute and relative values of the pulse heights.
  • the different pulse heights are a measure of the concentration of the substance you are looking for.
  • the signals received by the detectors 9a, 13 and 15 are passed into the signal conditioning circuits 21, 22 and 23, respectively. If more than one reference cuvette 5a ... 5z is used, as described below, a switch (not shown) is to be provided in front of the signal conditioning circuit 21, which selector selects the signal from the detectors 9a ... 9z of the reference cuvette 5a ... 5z just used.
  • the signal conditioning circuits 21, 22 and 23 have connected in series, as shown in FIG. 4, for the electrical signal coming from the detector 9a, 13 and 15, respectively Preamplifier 33, a filter 35, a time and frequency selective gate circuit 37 and 39 and a demodulator 41.
  • the time selective gate circuit 37 is controlled by the driver 30 such that it only allows signals to pass that appear at the time when the transmitter 3 Pulse were transmitted and the same pulse shape as the transmitted pulses had.
  • the filter 35 is designed as a bandpass filter with a center frequency which corresponds to the reciprocal value 1 / T T of the pulse spacing T T of the pulses of the radiation f 1 and f 2 . That is, the center frequency of the bandpass 35 is twice the frequency of the pulse repetition frequency of the pulses with the radiation frequency f 1 or f 2 .
  • the output signal is supplied to the demodulator 41 for amplitude modulated signals.
  • the frequency-selective gate circuit as a bandpass filter 39 has a center frequency which corresponds to the reciprocal value 1 / T N of the pulse spacing T N of the pulses of the radiation f 1 or f 2 .
  • the output signal of the bandpass 39 is fed to the evaluation circuit 25.
  • the bandwidth of the bandpass 35 is set so that the carrier signal with the frequency 1 / T T can pass unhindered together with the useful signal with the frequency 1 / T N.
  • the bandwidth of the bandpass filter 39 with the center frequency 1 / T N is set so that, on the one hand, changes in the signal can occur unhindered by changes in concentration, signal falsifications by, for. B. the thermal noise in the measuring medium 1, due to brief interruptions due to dust within the rays or variations in the measuring signal due to the radiation-deflecting temperature gradient in the measuring medium 1 can have no influence on the measuring signal.
  • the signal picked up by the detector 9a is processed analogously to what has been said above and is also sent from its demodulator (designed analogously to the demodulator 41) to the evaluation circuit 25.
  • the difference between the signals coming via the lines is weighted with the known concentration in the reference cell 5a and gives the desired concentration in the measuring medium 1.
  • the electrical signal which goes directly to the detector 15, is processed analogously.
  • the signal demodulated with the demodulator (designed analogously to the demodulator 41) is ideally a DC voltage signal of the same level.
  • the signal from the detector 15 also serves to monitor the output power of the transmitter 3.
  • a switching frequency 1 / T T appears in addition to a series of high frequencies, caused by the pulse shape, which corresponds to the reciprocal value of the time interval T T of successive pulses of the first and second radiation f 1 and f 2 and to the left and right of this switching frequency value 1 / T ⁇ , as shown in Figure 8, two further frequency values, which are the sum or the difference of the switching frequency value 1 / T ⁇ and a frequency value that is the reciprocal of the time interval T N of the successive pulses corresponds to the radiation f 1 or f 2 .
  • the amplitude of the frequency values changes in accordance with the instantaneous concentration 1 / T T + 1 / T N and 1 / T T - 1 / T N. If the pulses are now emitted by the transmitter 3, as described above, in such a way that the pulses are equidistant from one another, the frequency value 1 / T T - 1 / T N is half as large as the frequency value 1 / T T , ie it is 1 / T N.
  • the determined concentration values are stored in the evaluation circuit 25 over an adjustable time range, in order to be able to transmit values to a control device 71 described below, provided that the measurement signal, as already described above, fails for a short time.
  • a unit consisting of the cuvettes 5a ... 5z and the detectors 9a ... 9z, 13 and 15 can be constructed from discrete components or cast as a block.
  • the partially transparent mirrors 7a ... 7z can also be integrated into the structural unit, in particular if the radiation is conducted in front of and behind the cuvettes 5a ... 5z by means of light guides.
  • the time sequence of the emission of the radiation pulses can be variable, it only has to be known to the evaluation circuit (25).
  • the operating states of a system described below such as B. engine temperature, fuel injection quantity, etc. are also stored with the measured concentration values in order to carry out an extrapolated calculation of future measured values to be expected.
  • the pulse width d is compared to the pulse repetition frequency 1 / T T greatly shortened, the center frequency of the bandpass 35 is set to an integer multiple of the repetition frequency 1 / T T.
  • the bandpass filter 35 can be omitted and a pulse amplitude demodulator can be used as the demodulator 41.
  • the gate circuit 37 can discriminate regarding the curve shape of the pulse to be received, which is caused by the absorption in the measuring medium 1 or in the reference cuvette 5a is not changed.
  • the signal detected by the detector 13 can be very noisy.
  • the duration of the pulses is adapted as far as possible to the duration of the pauses between the pulses for optimal signal evaluation.
  • the signal from the detectors 9a (... 9z) and 13 is fed to a switching network 44 after processing by means of amplifier 33 and filter 35, which forwards the signals according to the control information of driver 30 to four downstream integrators 47a to 47d.
  • the integrals do not have to be determined at the same time, but only all must be available at a predetermined point in time at the end of the measurement period, the integrals can be determined either via a single integrator with a subsequent event switch or via the four integrators 47a to 47d.
  • an integral I 1 or I 2 is formed for the time range during which a pulse with the radiation f 1 or f 2 is emitted.
  • Further integrals I 3 and I 4 are formed in the pulse-free time between the pulses with the radiation f 1 and f 2 and the pulses with the radiation f 2 and f 1 .
  • the evaluation circuit 25 is subtracted from the value of the integral I 1, the value of the integral I 3 and the electrical signal obtained in this way is set to zero with the radiation f 2 before the pulse is emitted.
  • the value of the integral I 4 is subtracted from the value of the integral I 2 and the electrical signal is also set to zero before the pulse is emitted with the radiation f 1 .
  • Such an evaluated pulse train is shown as an abscissa in FIG. 8 over time t.
  • the searched concentration results from the difference values of the difference A of the maximum integral values for the signal of the detector 13 to the signal of the detector 9a. Measurement disturbances which occur in the period in which there should be no signal appear, as shown in FIG. 7, as a negative peak B or as a positive step (not shown).
  • the integral is formed over each pulse and discharged in the subsequent pauses with a discharge time constant which is set such that it just discharges an integrated pulse with the radiation f 1 through the reference cuvette 5a back to zero, the electrical values result before the zeroing a measure of concentration.
  • the reference cuvette 5a with a known concentration of a known substance is used.
  • z cuvettes with other substances of known concentration can also be used.
  • the partial beam of the transmitter 3 is passed through the relevant partially transparent mirror 7z through the relevant cuvette ... 5z.
  • the at least two narrow-band radiations with a repetition frequency in the kilohertzbe emits rich, suitable lasers such as diode lasers, dye lasers, CO 2 lasers, two spectral lamps, which are alternately covered by a rotating impeller, etc.
  • the lasers can be tuned to the two different frequencies by their excitation z. B. is pulsed by electric current, and between the pulses z. B. a grating or a resonator mirror is adjusted so that the laser vibrates at the desired resonance frequency.
  • Lamps can also be used in front of which an impeller rotates with filters which are separated from one another by non-transmitting areas.
  • the transmission curves of the filters are selected so that they meet the above conditions.
  • the number of revolutions of the filter wheel and the number of filter segments is selected such that the resulting switching frequency corresponds to the center frequency of the bandpass filter 35.
  • the absorption wavelengths of the substances whose concentration is to be determined in the measuring medium 1 are often close to one another, and the absorption bandwidths are often very narrow.
  • a precise setting of the radiation f 1 and f 2 can be achieved in that the radiation of the transmitter 3 is sent through the corresponding reference cuvette filled with the substance in question and the frequency f 1 and f 2 of the transmitter 3 is changed until the radiation is within or outside the bandwidth of the absorption.
  • An automatic monitoring of the frequencies f 1 and f 2 to be set can also be arranged in this way.
  • the beam splitter mirror 11 can be dispensed with and instead the one laser beam that emerges at a resonator mirror into the measuring medium 1 and the other laser beam that at other resonator mirror emerges to the Reference cuvettes 5 are sent.
  • the detector 13 is arranged next to the transmitter 3 and the detectors 9a ... 9z are arranged in front of the reference cuvettes 5a ... 5z in order to measure the intensity of the radiation scattered back from the measuring medium or the relevant reference cuvette.
  • the pulse shape of the backscattered pulses suffers from "smearing" compared to the emitted pulse shape, which, however, need not be taken into account in the measurement method described above, provided the pulse transit time through the measuring medium 1 and the reference cuvette 5a ... 5z is short in relation to the pulse width d of the emitted Is pulses.
  • the particle concentration in a flowing medium can also be determined by evaluating the backscattered radiation.
  • the amount of the substance or the amount of the reagents can also be adjusted so that after passing through the reaction zone there is so much of the substance or the reagents that further processes with or without concentration measurement are carried out in further reaction zones can be.
  • These processes are not only suitable for the removal of environmentally harmful substances, but can also be used in the chemical industry to produce highly sensitive products and to carry out chemical processes in which precisely metered quantities of substances and reagents have to be used.
  • a system in which the above-described devices for measuring the concentration of at least one substance contained in a fluid can be integrated is described below using the example of exhaust gases to be denitrified from a diesel engine 51 as an internal combustion engine.
  • nitrogen oxide NO and nitrogen dioxide NO 2 are reduced as pollutants in the exhaust gases of the diesel engine 51.
  • the system is shown in the block diagram in FIG poses. After leaving the engine 51, the exhaust gases flow through a (not absolutely necessary) particle filter 53. They then flow past sensors 57 of an engine control circuit 59 which are arranged in an exhaust pipe 55 and serve, among other things, to determine the pressure in the exhaust pipe 55 or, depending on the measured pressure to control a turbocharger.
  • a reaction region 61 follows in terms of flow behind the sensors 57, which is shown with a broken line in FIG. 9.
  • a feed device 63 for fresh air and a feed device 65 for ammonia open into the reaction area 61.
  • a catalytic converter 67 is connected downstream of the reaction area 61, followed by a concentration measuring point 69.
  • the catalytic converter can also be omitted in engines with exhaust gas temperatures above 1000 ° C.
  • the concentration measuring point 69 and the feed units 63 and 65 for fresh air and ammonia as well as the motor control circuit 59 are connected to a control device 71.
  • the control device 71 is assigned a value memory 73, already mentioned above, in which data for setting the feed units 63 and 65 depending on the engine data such as temperature, number of revolutions, amount of fresh air drawn in, measured with a fresh air amount measurement 75, which is connected to the engine control circuit 59, and injected amount of fuel, which is controlled by the engine control 59 via the injection nozzles 77, are stored.
  • the control device 71 is connected to the power amplifier 26.
  • the values to be measured in the concentration measuring point 69 are also stored in the value memory 73 in association with one or some of the motor data.
  • nitrogen oxide NO and nitrogen dioxide NO 2 contained in the exhaust gases are converted into water H 2 O and nitrogen N 2 in the catalyst 67.
  • the measuring point 69 continuously measures, ie with a measuring frequency of about 500 Hz, the ammonia content in the exhaust gases behind the catalytic converter 67.
  • the data already stored in the memory 73 are overwritten so that, on the one hand, virtually no ammonia is present in the exhaust gases the environment is released and on the other hand the NO and NO 2 content is kept as low as possible.
  • the dioxin emissions in internal combustion engines are significantly reduced.
  • the storage of the data in the memory 73 can serve, as already mentioned above, to carry out a measurement value extrapolation in the case of measurement values which fail for a short time.
  • the rapid measurement according to the invention which takes place in the sub-second time range, results in a significant reduction in the pollutant content even with rapid load changes on the diesel engine.
  • the NO and NO 2 content or both or the content of other substances can also be measured depending on the radiation frequencies used.
  • the sulfur dioxide content in exhaust gases and the content of other undesirable pollutants can be determined analogously.
  • the concentration of these substances in the measuring medium 1 can be determined, even if the absorption lines of individual substances partially overlap. In this case, the concentration is determined by forming the difference between the measured concentrations at different frequencies.
  • some of the reference cuvettes 9a to 9z can also be filled with the same substances but with different concentrations. This method is indicated if measurements are to be carried out over large concentration ranges. In accordance with the measured concentration values, the admixed quantity of reagents and the process parameters - temperature, pressure, flow rate, ... - can be changed in such a way that the pollutant concentration is minimal.
  • the method according to the invention can be carried out not only with gases, but also with liquids.
  • the NO x content in the combustion gases changes with the combustion temperature.
  • the diesel engine z. B. increases the combustion temperature with increasing output and thus also the NO x content in the exhaust gases.
  • the control device 71 In order to be able to work with the control device 71 with largely eliminating a dead time which is due to the setting time of the reagent inflow through the supply units 63 and 65 for fresh air and ammonia and the time which elapses until both reagents are in the reaction area 61, the measured values are measured and the concentration measurement values stored in the memory 73 are extrapolated in time, taking into account the above dead time, and from this using the operating data of the diesel engine 51 set by the engine controller 59, the inflow rate of regents is calculated, which is based on the dead time is to be fed into the reaction area 61 through the feed units 63 and 65.

Abstract

Le procédé de mesure de la concentration de substances, basé sur le fait qu'un rayonnement est absorbé dans le domaine d'absorption du rayonnement de la substance et qu'un autre n'est pas absorbé, fonctionne avec des impulsions de même fréquence de répétition d'impulsion et avec de mêmes intervalles d'impulsion. Le signal électrique détecté, dont la fréquence moyenne correspond à la valeur inverse de l'intervalle d'impulsion, est filtré à sa sortie au moyen d'un filtre. La concentration de la substance absorbante est déterminée à partir des variations d'amplitude du signal filtré à la sortie. Dans un dispositif pour la mise en oeuvre du procédé précité, on utilise des filtres dont les bandes passantes sont adaptées respectivement aux fréquences de répétition d'impulsion existantes. Du fait de l'interprétation du signal de mesure sous forme de signal modulé, une fiabilité élevée vis-à-vis de signaux parasites est obtenue. Lorsque le dispositif est monté dans un appareillage comportant des moyens d'amenée permettant l'addition d'un réactif transformant la substance précitée par réaction chimique, la concentration de la substance dans un fluide peut varier, et notamment, diminuer, suivant les valeurs de concentration mesurées dans un intervalle de temps inférieur à la seconde. L'appareillage convient notamment pour l'élimination de l'azote dans les gaz d'échappement des moteurs à combustion interne.
EP19910914541 1990-09-07 1991-08-26 Procede pour la determination de la concentration de substances, dispositif pour la mise en uvre de ce procede, application dudit procede pour faire varier la concentration d'une substance contenue dans un fluide et appareillage y relatif Withdrawn EP0503011A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
CH291390 1990-09-07
CH2913/90 1990-09-07
CH663/91 1991-03-05
CH66391 1991-03-05

Publications (1)

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EP0503011A1 true EP0503011A1 (fr) 1992-09-16

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EP (1) EP0503011A1 (fr)
JP (1) JPH05503359A (fr)
AU (1) AU8324291A (fr)
MX (1) MX9100960A (fr)
PT (1) PT98848A (fr)
WO (1) WO1992004614A1 (fr)

Families Citing this family (3)

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Publication number Priority date Publication date Assignee Title
DE4342246C2 (de) * 1993-12-10 1997-03-20 Karl Stefan Riener Charakteristische Absorption
EP0657731B1 (fr) * 1993-12-10 1999-04-14 Karl Stefan Riener Procédé et appareil pour déterminer une absorption caractéristique d'une substance
AU2003228181A1 (en) * 2002-05-27 2003-12-12 Sensortec Limited Improved detection system and method of detection

Family Cites Families (7)

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Publication number Priority date Publication date Assignee Title
US3804535A (en) * 1972-10-13 1974-04-16 Baxter Laboratories Inc Dual wavelength photometer response circuit
DE2635171C3 (de) * 1976-08-05 1980-06-19 6000 Frankfurt Gerät zur Bestimmung der Konzentration eines Bestandteils einer Gasprobe
DE3137658C2 (de) * 1981-09-22 1985-06-05 H. Maihak Ag, 2000 Hamburg Vorrichtung zur Messung der Konzentration eines IR-, NIR-, VIS- oder UV-Strahlung absorbierenden Gases in einer Gasmatrix
DE3615260C2 (de) * 1986-05-06 1994-09-01 Krieg Gunther Verfahren und System zur Detektion von optisch absorbierenden Verbindungen in einem Medium durch optische Transmissionsmessung
DE3741026A1 (de) * 1987-12-03 1989-06-15 Muetek Laser Und Opto Elektron Verfahren und system zur (spuren-) gasanalyse
DE3819531A1 (de) * 1988-06-08 1989-12-14 Reiner Dipl Phys Szepan Signalprozess- und betriebstechnik zur laserspektroskopischen mengenbestimmung von ammoniak in gasgemischen
DE3825206A1 (de) * 1988-07-25 1990-02-01 Degussa Verfahren zur katalytischen entstickung von abgasen mittels eines reduktionsmittels

Non-Patent Citations (1)

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Title
See references of WO9204614A1 *

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PT98848A (pt) 1993-11-30
JPH05503359A (ja) 1993-06-03
AU8324291A (en) 1992-03-30
MX9100960A (es) 1992-05-04
WO1992004614A1 (fr) 1992-03-19

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