Measuring device and method for measuring at least two different components of a fluid

Abstract

The present invention relates to a measuring device and a method for measuring at least two different components of a fluid (3), in which the fluid (3) is conveyed to a first measuring unit and a second measuring unit (46), wherein in the first measuring unit (2) a first component of the fluid (3) is excited by means of a first excitation (6), and thereby a first light emission line (15, 45) is triggered, and wherein in the second measuring unit (46) at least one second component of the fluid (3) is excited by means of a second excitation (47) different from the first excitation (6), and thereby a second light emission line (48) is triggered, and wherein the first light emission line (15, 45) and the second light emission line (48) are received by means of an optical device (12, 33) and guided in the direction of a detector device (29, 43), and wherein the detector device (29, 43) measures the first light emission line (15, 45) and the second light emission line (48).

Description

Field of the Invention

[0001] The present invention relates to a method and a measuring device for measuring at least two different components of a fluid. In particular, the present invention relates to an automatic measuring device and method for measuring gases, especially gases in the exhaust gases of stationary and mobile sources. Background Art

[0002] For example, the minimum requirements and test procedures for automatic measuring devices for monitoring emissions from stationary sources are described in the standard DIN EN 15267-3. For this purpose, it is necessary to measure nitrogen oxides (NO x x). Here, it is the sum of the gas components NO and NO2. In addition, despite the progress of the decarbonization of the global economy, the measurement of nitrogen oxides still plays an important role. For example, when burning hydrogen in a gas turbine (in support of the future of renewable sources and the generation of electricity for hydrogen aircraft and sea vessels), NO x emissions are still expected.

[0003] Measurement methods for measuring NO or NO2 for certified measuring systems are known from the prior art. Of course, the disadvantage of these methods is that they can always only measure one component of the gas.

[0004] Therefore, there is a great need for a method and a measuring device for measuring at least two different gas components. Summary of the Invention

[0005] Therefore, an object of the present invention may be to meet the above-mentioned needs.

[0006] According to the present invention, the above object is achieved by a method for measuring at least two different components of a fluid by preferably simultaneously feeding the fluid to a first and a second measuring unit, wherein in the first measuring unit at least one first component of the fluid is excited by means of a first excitation, and thereby a first light emission line is triggered, and wherein in the second measuring unit at least one second component of the fluid is excited by means of a second excitation different from the first excitation, and thereby a second light emission line is triggered, and wherein the first light emission line and the second light emission line are received by means of an optical device and directed in the direction of a detector device, and wherein the detector device measures the first light emission line and the second light emission line.

[0007] The use of two different excitations, for example two different types of excitations, in two different measuring units enables the simultaneous and independent measurement of two different components, for example the concentrations of nitric oxide and nitrogen dioxide.

[0008] In one embodiment, it can be proposed that the second measuring unit is constructed structurally separately from the first measuring unit.

[0009] In one embodiment, it can be proposed that the detector device comprises two detector means which are structurally separated from one another, such as detectors, in particular photomultipliers.

[0010] In one embodiment, it can be proposed that the optical device comprises two optical means which are structurally separated from one another.

[0011] In one embodiment, it can be proposed that the detector means are respectively assigned to the optical means.

[0012] In one embodiment, it can be proposed that the first excitation is laser excitation.

[0013] In one embodiment, it can be proposed that the first component is nitrogen dioxide.

[0014] In one embodiment, it can be proposed that a laser light source having a wavelength adapted to the electronic transition in nitrogen dioxide molecules is used for laser excitation.

[0015] In one embodiment, it can be proposed that the laser emitted by the laser light source has a wavelength of approximately 405 nm ± 10 nm.

[0016] In one embodiment, it can be proposed that the first optical emission line is Raman radiation.

[0017] In one embodiment, it can be proposed that the second excitation is effected by metering reactants which cause chemiluminescence with the second component of the fluid.

[0018] In one embodiment, it can be proposed that the reactants comprise ozone, preferably and / or the second component is nitric oxide.

[0019] In one embodiment, it can be proposed that the first optical emission line and the second optical emission line are measured simultaneously.

[0020] In one embodiment, it can be proposed that a first bandpass filter (for example having a central wavelength of approximately 477 nm and a full width at half maximum of approximately 10 nm) is used for measuring the first optical emission line and / or a second bandpass filter (for example having a central wavelength of approximately 650 nm and a full width at half maximum of approximately 100 nm) is used for measuring the second optical emission line.

[0021] The bandpass filter can, for example, be arranged in the optical device in a replaceable manner.

[0022] In one embodiment, it can be proposed that the first and second bandpass filters are used alternately or simultaneously.

[0023] In one embodiment, it can be proposed that the first optical emission line is measured using a first part of the detector device and / or the second optical emission line is measured using a second part of the detector device.

[0024] In one embodiment, it can be proposed that the first and second components of the fluid are excited and / or measured simultaneously (in parallel).

[0025] In one embodiment, it can be proposed that the first light emission line includes the light emission line of the first component and the light emission lines of other components different from the first component.

[0026] In one embodiment, it can be proposed that the light emission lines of the first component and the light emission lines of other components are measured alternately or simultaneously.

[0027] In one embodiment, it can be proposed that different band-pass filters are used to measure the light emission lines of the first component and the light emission lines of other components, for example, they are installed in the optical device.

[0028] Furthermore, the above object is also achieved by a measuring device for measuring at least two different components of a fluid, wherein the measuring device includes: a first measuring unit, an excitation device, an optical device, and a detector device, wherein the first measuring unit is configured such that the fluid can be conveyed to the first measuring unit, wherein the excitation device is assigned to the first measuring unit and is arranged to generate a first excitation for exciting at least a first component of the fluid when the fluid is conveyed to the first measuring unit, wherein the optical device is assigned to the first measuring unit and is arranged to receive a first light emission line that can be triggered by the first excitation and guide it in the direction of the detector device, and wherein the detector device is assigned to the optical device and is arranged to measure the first light emission line.

[0029] Furthermore, according to the present invention, the measuring device has a second measuring unit, wherein the second measuring unit is configured such that the fluid can be conveyed to the second measuring unit, wherein when the fluid is conveyed to the second measuring unit, the second component of the fluid in the second measuring unit can be excited by a second excitation different from the first excitation, wherein the optical device is assigned to the second measuring unit and is arranged to receive a second light emission line that can be triggered by the second excitation and guide it in the direction of the detector device, and the detector device is arranged to measure the second light emission line.

[0030] The measuring device can be constructed to be sufficiently compact. For example, the measuring device is approximately 35 cm × 35 cm, so that the measuring device can be placed in a shoe box. In short, the measuring device is configured such that it can thus measure the gas of a mobile source. In addition, the measuring device requires almost no sample preparation.

[0031] It goes without saying that the fluid flows through the first and second measuring units during the measurement.

[0032] In one embodiment, it can be proposed that the first / second light emission line is specific or characteristic for the first / second component.

[0033] In one embodiment, it can be proposed that the first and second light emission lines are different from each other, for example, their (central) wavelengths are different.

[0034] In one embodiment, it can be proposed that the excitation device is a laser light source and the first excitation is a laser excitation.

[0035] In one embodiment, it can be proposed that the laser light source is configured to emit a laser with a wavelength of approximately 405 nm ± 10 nm.

[0036] In one embodiment, it can be proposed that the first light emission line is Raman radiation.

[0037] In one embodiment, it can be proposed that the second measuring unit is not pressure-resistant.

[0038] In one embodiment, it can be proposed that the measuring device further includes another excitation device assigned to the second measuring unit, and the other excitation device is configured to generate a second excitation in the second measuring unit.

[0039] In one embodiment, it can be proposed that the second excitation is carried out by adding a reactant that can chemically react with the second component and trigger chemiluminescence.

[0040] In one embodiment, it can be proposed that the other excitation device is configured as a reactant generator device, for example, configured as an ozone generator, and the reactant generator device is configured to deliver the reactant to the second measuring unit.

[0041] In one embodiment, it can be proposed that the second light emission line is a chemiluminescence emission line. Thus, the measuring device can be designed to simultaneously measure nitrogen dioxide and nitric oxide. Here, the concentrations of nitrogen dioxide and nitric oxide can be determined simultaneously based on the combined Raman and chemiluminescence measurements.

[0042] In one embodiment, it can be proposed that the second measuring unit has an inlet and an outlet for the fluid and another inlet, wherein the reactant can enter the second measuring unit through the other inlet, and the reactant can chemically react with the second component of the fluid and can generate a chemiluminescence emission line and thus can be the second excitation.

[0043] In one embodiment, it can be proposed that the optical device includes a chamber for accommodating the reactant.

[0044] In one embodiment, it can be proposed that the reactant can be delivered to the chamber via a capillary.

[0045] In one embodiment, it can be proposed that the chamber has a wall shared with the second measuring unit, and the other inlet is arranged at or formed in the wall.

[0046] In one embodiment, it can be proposed that the chamber is separated from the second measuring unit by a slit partition, for example, a common wall is configured as the slit partition.

[0047] In one embodiment, it can be proposed that the opening of the slit partition is arranged in the focus of at least one lens of the optical device.

[0048] In one embodiment, it can be proposed that the size of the opening of the slit partition corresponds to the size of the photocathode of the detector device, preferably being approximately the same size as the photocathode.

[0049] In one embodiment, it can be proposed that the first measuring unit is pressure-resistant.

[0050] In one embodiment, it can be proposed that the first measuring unit has at least one pressure-resistant window, wherein each pressure-resistant window is configured as an incident optical device of the optical device.

[0051] In one embodiment, it can be proposed that the optical device includes a first receiving optical device and a second receiving optical device.

[0052] In one embodiment, it can be proposed that the first receiving optical device is structurally separated from the second receiving optical device.

[0053] In one embodiment, it can be proposed that the first receiving optical device includes the second measuring unit and / or the chamber.

[0054] In one embodiment, it can be proposed that the first excitation excites at least one other component in the fluid that is different from the first component in the first measuring unit, such that the first light emission line includes the light emission line of the first component and the light emission lines of the other components.

[0055] In one embodiment, it can be proposed that the second receiving optical device is assigned to the first measuring unit and is configured to select the light emission lines of the other components and direct them towards the detector device, and the detector device is assigned to the second receiving optical device and is configured to measure the light emission lines of the other components.

[0056] In one embodiment, it can be proposed that the other component is different from the first component and the second component, for example, it is oxygen. For example, oxygen is specified as a measuring component in NOx emission measurement.

[0057] In one embodiment, it can be proposed that the first receiving optical device and the second receiving optical device are configured to select the light emission lines of the first component. This can be achieved, for example, by using the same bandpass filter in the first receiving optical device and the second receiving optical device.

[0058] In one embodiment, it can be proposed that the other light emission lines are specific / characteristic for the other components.

[0059] In one embodiment, it can be proposed that the optical device comprises at least one bandpass filter device, wherein the bandpass filter device is configured to select the light emission lines specific to the fluid components.

[0060] In one embodiment, it can be proposed that at least one bandpass filter device has two or more bandpass filters.

[0061] In one embodiment, it can be proposed that one or more of the bandpass filters have one or more interference filters.

[0062] In one embodiment, it can be proposed that the different bandpass filters have different center wavelengths and full widths at half maximum.

[0063] In one embodiment, it can be proposed that the respective center wavelengths and full widths at half maximum are selected to adapt to the detection of the respective light emission lines.

[0064] In one embodiment, it can be proposed that the bandpass filter device comprises a filter wheel arranged at a first receiving optical device and other bandpass filters arranged at a second receiving optical device.

[0065] In one embodiment, it can be proposed that the optical device has at least one first section and at least one second section, wherein at least one first section is provided for spatially filtering the light emission lines that can be triggered in a first measuring unit, and at least one second section is provided for imaging and preferably for selecting the spatially filtered light emission lines that can be triggered in the first measuring unit onto a detector device.

[0066] In one embodiment, it can be proposed that the exit optical device of the first section encloses a chamber at the side opposite to the wall (shared with a second measuring unit), for example opposite to a slit separator, wherein the exit optical device can for example be configured as a focusing lens.

[0067] In one embodiment, it can be proposed that the entrance optical device of the second section closes the second measuring unit on the detector device side - i.e. at the side opposite to the wall (shared with a second measuring unit), wherein the entrance optical device can for example be configured as a collimating lens. Description of the Drawings

[0068] Other features, characteristics and advantages of the present invention result from the following description with reference to the drawings. Which are schematically shown:

[0069] Figure 1 A schematic illustration showing a perspective view of a Raman photometer,

[0070] Figure 2 Showing Figure 1The first cross-sectional view of a Raman photometer,

[0071] Figure 3 shows Figure 1 the second cross-sectional view of a Raman photometer,

[0072] Figures 4 to 6 showing different Raman measurements.

[0073] In the embodiments and the drawings, elements that are the same or perform the same function may be provided with the same reference numerals, respectively. Detailed description of the embodiments

[0074] Figure 1 shows a Raman photometer or a Raman scattered light photometer 1, which may correspond to the measuring device according to the invention. The Raman photometer 1 has a first measuring unit 2, which is preferably pressure-resistant (e.g., 10 bar), for example, cubic in shape, and can be absolutely penetrated by a fluid 3 (e.g., a gas, especially the exhaust gas from combustion) at a regulated pressure of up to 10 bar. The fluid 3 can enter the first measuring unit 2 via the inlet 4 of the inlet chamber and leave at two exhaust ports 5, where the exhaust ports 5 are preferably arranged at right angles to the first measuring unit 2 and lead out of the first measuring unit 2 upward and downward in the figure.

[0075] A laser device having a laser light source 7 is assigned to the first measuring unit 2 and is preferably arranged relative to the inlet chamber and preferably fixed to the first measuring unit 2.

[0076] From Figure 1 it can be seen that the measuring device 1 has optical devices 12, 33. The optical devices 12, 33 are also assigned to the first measuring unit 2 and are designed to receive in the first measuring unit 2 the light emission lines 15, 45 triggered by the laser excitation 6 provided by means of the laser light source 7 (see Figure 2 and Figure 3 ) and image them onto the detector devices 29, 43.

[0077] The optical device may have a first receiving optical device 12 and / or a second receiving optical device 33.

[0078] Furthermore, from Figure 1 it can be seen that the first receiving optical device 12 has a filter wheel 21, which has a plurality of band-pass filters 20 (see Figure 2 and Figure 3 ) 22, 23, 24, 25, 26 for selectively filtering the radiation of the emitted lines in a fluid-component-specific manner.

[0079] Figure 2 shows a cross-sectional view of the Raman photometer 1.

[0080] The light beam 6 of the laser light source 7 falls into the measuring unit 2, for example, through the partition 8, via the focusing lens 9 and the interference filter 10, and transmits through the measuring unit in the direction of the intake port 4, where the light beam is received, for example, in the light trap 11 without backscattering. The linearly-segmented (beam waist) portion of the light beam 6 (Gaussian beam) focused by the lens 9 can be positioned at the center of the first measuring unit 2 so as to generate, for example, the maximum light output there in the case of exciting the corresponding fluid components. In addition, the center of the first measuring unit can be arranged in the foci of the incident lenses 16, 36 of the first or second receiving optical devices 12, 33.

[0081] The beam quality and line width of the laser beam 6 can be improved by the partition 8 and, for example, the narrow-band interference filter 10, such that the background signal in the first measuring unit 2 can be placed at a low level. In addition, the background signal can be strongly reduced by the arrangement and design of the exhaust port 5 and the light trap 11.

[0082] Figure 3 Another sectional view of the Raman photometer 1 is shown.

[0083] The first receiving optical device 12 and the second receiving optical device 33 for Raman photons 15, 45 scattered at the molecules of the fluid 3 can be arranged at right angles to the laser beam 6 and preferably attached to the first measuring unit 2. Preferably, the second receiving optical device 33 is arranged opposite to the first receiving optical device 12.

[0084] It should be noted in this regard that the use of the two receiving optical devices 12, 33 is optional.

[0085] One or more components of the fluid 3 can be excited by the laser 7. Thus, a plurality of wavelength-specific light emission lines 15, 45 can be formed in the first measuring unit 2, and the light emission lines are triggered by the laser excitation 6 of different components of the fluid 3.

[0086] In one embodiment, the different fluid components that can be excited by the laser excitation 6 can be detected by using only the first receiving optical device 12 in the following manner: namely, by alternately using different band-pass filters 20, 22, 23, 24, 25, 26.

[0087] In order to simultaneously detect different light emission lines 15, 45 from the first measuring unit 2, it is advantageous to use the second receiving optical device 33. In this case, different band-pass filters 20, 40 can be used in the first and second receiving optical devices 12, 33, and the band-pass filters are selected to be adapted to the corresponding light emission lines 15, 45.

[0088] The selection of the adapted bandpass filters 20, 22, 23, 24, 25, 26, 40 for detecting the corresponding Raman radiations 15, 45 can be summarized in tabular form as follows.

[0089] Table 1: Selection of the center wavelengths of the bandpass filters for different gas components in the case of a laser with a wavelength of 402 nm.

[0090]

[0091]

[0092] Here, RRS stands for resonance Raman scattering.

[0093] It can be seen from Table 1 that the measurement of oxygen at 429 nm using a bandpass filter with a full width at half maximum (FWHM) of 10 nm will be interfered by CO2 (the measurement gas 3 contains up to 15% by volume). If the bandpass filter for O2 cannot be selected correspondingly narrowly, additionally, for example, a bandpass filter for CO2 can be used in the filter wheel 21, and a two-component determination can be performed via series measurements (according to the MLR calibration method, matrix inversion according to the multiple linear regression method). The best wavelength for detecting NO2 is 477 nm, where the possible cross-sensitivity of hydrogen and water can be excluded by the FWHM of the 10 nm bandpass filter.

[0094] The receiving optical devices 12, 33 can each have two segments 13, 14 and 34, 35, wherein in each first segment 13, 34, the scattered lights 15, 45 are focused onto a rectangular partition 18 by means of one or more lenses 16, 17. For example, the partition 18 can form a slit aperture. For example, the opening 52 can have dimensions of approximately 1×4 mm.

[0095] Spatial filtering of the scattered lights 15, 45 can be achieved through the first segments 13, 34, such that only the photons that have scattered from the limited volume of the focused line segment that annularly surrounds the laser beam 6 reach the corresponding second segments 14, 35. The incident lenses 16, 36 of the corresponding first segments 13, 34 can be used as pressure-resistant closures or pressure-resistant windows of the first measurement unit 2.

[0096] In the respective second sections 14, 35, the scattered light 15, 45 collimated by means of the lenses 19, 39 passes through the respective bandpass filters 20, 40. Each of the bandpass filters 20, 22, 23, 24, 25, 26, 40 discussed within the scope of the present disclosure can be formed in the form of an interference filter with a narrow band (full width at half maximum (FWHM) = 5 - 10 nm for Raman photons) or, if necessary, two successively arranged interference filters. The photons selected in a gas-component-specific manner by the respective bandpass filters 20, 40 can be imaged, by means of additional lenses 21, 41, onto a photoelectric cathode 28, 42, for example rectangular (e.g., approximately 1 × 4 mm in size), of the respective photomultiplier 29, 43, and the photons can be detected individually by means of the photomultiplier. Each photomultiplier 29, 43 generates an output signal (e.g., a Raman signal when photons are detected from the first measuring unit 2) 30, 44, which is proportional to the number of photons absorbed by the photoelectric cathodes 28, 42 per unit time, and is fed to an evaluation device (processor) 31 for evaluating and determining and outputting 32 the concentration of the measured fluid component.

[0097] The respective photomultipliers 29, 43 serve to convert the Raman photons, which are produced in very small amounts especially also due to the low laser power, into an output signal 30, 44 that is strong enough. In addition, the measurement can be carried out, for example, at an absolute pressure of 5 bar in the case of a pressure increase in the first measuring unit 2, since the number of Raman photons generated and thus the Raman signals 29, 43 increase proportionally to the measurement gas pressure. For this purpose, a pressure regulator (not shown) can be provided, if necessary, at the converging exhaust port 5.

[0098] In one embodiment, a laser light source 7 with a wavelength adapted to the electronic transition in the NO2 molecule can be used in order to enable a sensitive detection (detection limit below 0.5 ppm (parts per million)) of NO2. For example, the wavelength of a laser diode of approximately 400 nm, for example 402 nm, in particular 405 nm, can be suitable for this. In the case of measuring O2 and other components (CO2 and N2) in the measuring gas 3, the above short wavelength can also provide a good Raman photon yield (proportional to ), and does not cause any fluorescence. Here, in the case of Raman scattering of NO2, it is advantageous that the principle of resonance Raman scattering (RRS) can be utilized by stimulated emission of the electronic energy levels. This can lead to an amplification of the output signals 30, 44 by approximately 100 times, and thus improve the detection limit.

[0099] In one embodiment, the bandpass filters 20, 40 can be selected such that, for example, nitrogen dioxide and oxygen are measured simultaneously according to the above Raman measurement method.

[0100] In addition, the laser power can be limited to below 35 mW to meet explosion protection requirements, where a detection limit of <1 ppm for nitrogen dioxide can be achieved during a measurement duration of 1 second.

[0101] In addition, the Raman photometer 1 is provided with a second measurement unit 46. The second measurement unit 46 is not pressure-resistant, for example.

[0102] The second measurement unit 46 is configured such that the measurement gas 3 can be fed thereto, and when the measurement gas 3 is fed into the second measurement unit 46, at least a second component of the measurement gas 3 can be excited in the second measurement unit 46 by a second excitation 47 different from the first excitation 6.

[0103] The second measurement unit 46 can be implemented as a chemiluminescence measurement unit. The second component of the measurement gas 3 is, for example, nitric oxide, which is converted to an excited state by feeding a reactant, such as ozone 47, and emits light due to de-excitation - i.e., chemiluminescence 48.

[0104] The chemiluminescence 48 of the reaction of nitric oxide (NO) with ozone 47 occurs in the range between approximately 600 nm and 3000 nm (for example, see: http: / / teaching.shu.ac.uk / hwb / chemistry / tutorials / molspec / lumin1.htm , retrieved on December 17, 2020). The photomultiplier tubes 29, 43 are preferably sensitive up to approximately 700 nm. Therefore, it is suitable to use a band-pass filter 22 with a FWHM of approximately 100 nm at 650 nm to measure the chemiluminescence photons.

[0105] The corresponding photomultiplier tubes 29, 43 are also used to convert the chemiluminescence photons 48 into an output signal (chemiluminescence signal) 30.

[0106] Therefore, the output signal can be, for example, a Raman or chemiluminescence signal.

[0107] Based on the output signals 30, 44, the concentration 32 of the first and / or second component (such as nitrogen dioxide and nitric oxide) can be determined.

[0108] From Figure 3 it can be seen that ozone 47 can be generated in an ozone generator 49. For example, ozone 47 can be generated from dry air 50 in a dielectric barrier gas discharge or by means of an ultraviolet lamp (for example, with a maximum intensity <220 nm). The advantage of the ultraviolet lamp is that nitrogen in the air does not produce nitrogen oxides here.

[0109] Ozone 47 can be fed to the second measurement unit 46 via a capillary (not shown), for example.

[0110] In one embodiment, the second measuring unit 46 can be configured as part of the optical devices 12, 33. In particular, the second measuring unit 46 can be implemented as an integrated component of the first receiving optical device 12( Figure 3 ) or the second receiving optical device 33 (not shown).

[0111] As can be seen from Figure 3 , the second measuring unit 46 can be formed by the space between the slit partition 18 arranged between the first and second sections 13, 14 of the first receiving optical device 12 and the (incident) lens 19 of the second section 14 of the first receiving optical device 12.

[0112] The exit lens 17 of the first section 13 can be implemented as a focusing lens, for example. The incident lens 19 of the second section can be implemented as a collimating lens, for example.

[0113] It should be noted in this regard that, as can be derived from Figures 1 to 3 , the first and second receiving optical devices 12, 33 and especially the sections 13, 14, 34, 35 have a substantially hollow cylindrical shape, wherein the optically active elements (lenses, partitions, bandpass filters) are accommodated in the receiving optical devices 12, 33 and especially in the sections 13, 14, 34, 35. The corresponding sections 13 and 14 or 34 and 35 can be screwed together. The receiving optical devices 12, 33 can also be screwed to the first measuring unit 2.

[0114] Furthermore, as can be seen from Figure 3 , the reactant 47 can be fed to the second measuring unit 46 via the chamber 51. The chamber 51 can be constructed in the first section 13 of the first receiving optical device 12. For example, the chamber 51 can be formed by the space between the exit lens 17 and the slit partition 18.

[0115] It would be useful if the reactant 47 (such as ozone) were fed to the chamber 51 via a capillary.

[0116] During the measurement of at least the second component of the measuring fluid 3 (such as nitric oxide), the measuring gas 3 flows through the second measuring unit 46 - through the inlet and outlet not shown here. At the same time, the reactant 47 can be fed to the first chamber 51 so that the reactant passes through the opening 52 of the slit partition 18 and reaches the second measuring unit 46. In this case, the mixing of the reactant 47 with the fluid 3 that causes chemiluminescence 48 takes place in the region of the opening 52 of the slit partition 18.

[0117] It is expedient to select the openings 52 of the (multiple) slit partitions 18, 38 to be the same size as the (multiple) cathodes 28, 42.

[0118] In one embodiment, the opening 52 of the slit separator 18 may be arranged in the common focus of the exit lens 17 of the first section 13 and the entrance lens 19 of the second section 14. In this way, the photons 48 formed by chemiluminescence can be received particularly simply and imaged onto the cathode 28 of the photomultiplier 29. As described above, here, a bandpass filter 22 with a 650 nm center wavelength and an FWHM of approximately 100 nm can be inserted into the second section 14 with the aid of the filter wheel 21 in order to selectively detect the chemiluminescence photons 48.

[0119] Figures 1 to 3 The measuring device 1 of achieves the simultaneous measurement of nitrogen dioxide (the first component of the fluid 3) and nitric oxide (the second component of the fluid 3). Here, the ozone metering does not have to be interrupted during the NO2 Raman measurement, as is the case when the fluid 3 is excited by the laser 6 and by the ozone 47 in the first measuring unit 2. In the case of such simultaneous excitation in the same measuring unit, the NO2 reaction products in the Raman signal are also measured jointly during the chemiluminescence measurement. In addition, other nitrogen oxides (N2O5, NO3) are formed in the reaction of NO with excess ozone, and these other nitrogen oxides are not detected in the Raman signal of NO2, such that it is necessary to measure NO and NO2 separately via two measuring methods in order to infer the NO x concentration 32.

[0120] The measuring method described in the present disclosure can be simply calibrated using a series of calibration gases. The measurement can be carried out at a continuous gas flow, where the results are available every second.

[0121] Figures 4 to 6 shows exemplary measurement results for the simultaneous determination of the NO2 and O2 concentrations with the aid of Figures 1 to 3 the measuring device 1.

[0122] The Raman photons 15, 45 from the electronically excited NO2 molecules are counted by the first receiving optical device 12 equipped with a bandpass filter 20 having a center wavelength (CWL) of 486 nm (or CWL 477 nm) using a photomultiplier 29.

[0123] The O2 measurement is carried out using the bandpass filter device 40. The bandpass filter device 40 includes a bandpass filter with a CWL of 430 nm. However, this bandpass filter also allows the Raman photons of NO2 and CO2 (carbon dioxide) to pass through. Therefore, in order to compensate for the O2 measurement, an additional bandpass filter with a CWL of 420 nm is provided in the bandpass filter device 40 in order to compensate for interfering components, for example by means of MLR calibration (matrix inversion according to the method of multiple linear regression) of CO2 and NO2.

[0124] In the filter wheel 21, for example, the following bandpass filters (BPF) can be used:

[0125] I. Semrock CWL 420nm FWHM 5nm

[0126] II. Edmund Optics CWL 430nm FWHM 10nm

[0127] III. Edmund Optics CWL 486nm FWHM 10nm

[0128] A test gas with a concentration of 960 mg / m 3 NO2 (relative measurement uncertainty < 2%) flows through the first measurement unit 2 (1 l / min). The test gas also contains 19.9% by volume of O2 to stabilize NO2, and the remainder of the test gas is N2. Based on the noise band and the Raman signals 30, 44 recorded per second, the minimum detectable concentration of 3 mg / m 3 is obtained (corresponding to approximately 1.5 ppm). In this measurement, the detection limit of O2 is 0.13% by volume, and the detection limit of CO2 is 0.22% by volume.

[0129] Figure 4 Shows the Raman measurement of 960 mg / m 3 NO2 with 19.9% by volume of O2. The signal is 240 seconds long, using BPF I., then using BPF II., and from 480 seconds onwards, using BPF III. The Raman signal is represented by signal pulses per second.

[0130] Figure 5 Shows the Raman measurement of synthetic air (80% by volume of N2 and 20% by volume of O2). The signal is 310 seconds long. Using BPF (band - pass filter) I., then using BPF II. The measurement using BPF III. is not shown because there is almost only the background signal of BPFIII. (about 470 cps (counts per second)).

[0131] Figure 4 and Figure 5 The measurement results in

[0132] Figure 6Additionally shown is the Raman measurement of 100 vol% CO2. The signal is 240 seconds long. In the case of logarithmic signal scaling, BPF I. is utilized, then BPF II., and from 480 s onwards BPF III.

[0133] In a practical exhaust application, it would be useful for the O2 signal (in the case of the main BPF II.) to be compensated by the CO2 signal, regardless of whether the CO2 concentration is above 15 vol%.

[0134] The measurement method described within the scope of the present disclosure for the combination of NO x and O2 can be calibrated using a series of test gases (NO, NO2, O2, CO2, the remainder being N2). By measuring the specific Raman photons of CO2 and H2O, the influence of CO2 and H2O on NO chemiluminescence through fluorescence quenching can be reduced. The measurement can be carried out continuously at the extracted gas flow, and due to the clock pulses of the filter wheel, the concentrations of the individual components can be provided at the latest with a minute clock pulse. If the measurement is not carried out with oxygen, the NO x measurement can also be carried out simultaneously using two receiving optical devices. A smaller detection limit can be achieved by increasing the laser power and by averaging the measured values.

[0135] The reference signs in the claims are only used to better understand the invention and do not in any way limit the invention.

[0136] Although the invention has been illustrated and described in more detail by way of examples, the invention is not limited by the disclosed examples. Those skilled in the art can derive variants thereof without departing from the scope of protection of the invention defined by the appended claims. In particular, the disclosed features of the measurement device described herein can meaningfully be used to improve the method described herein, and vice versa.

Claims

1. A method for measuring at least two different components of a fluid (3), wherein, The fluid (3) is conveyed to a first measuring unit and a second measuring unit (46), wherein in the first measuring unit (2) a first component of the fluid (3) is excited by means of a first excitation (6), and a first light emission line (15, 45) is triggered by the excitation, wherein in the second measuring unit (46) at least one second component of the fluid (3) is excited by means of a second excitation (47) different from the first excitation (6), and a second light emission line (48) is triggered by the excitation, wherein the first light emission line (15, 45) and the second light emission line (48) are received by means of an optical device (12, 33), and the first light emission line and the second light emission line are guided in the direction of a detector device (29, 43), wherein the detector device (29, 43) measures the first light emission line (15, 45) and the second light emission line (48). wherein the first excitation is a laser excitation (6), the first light emission line (15, 45) is Raman radiation and the second excitation (47) is carried out by metering a reactant which causes chemiluminescence with the second component of the fluid (3). wherein the optical device has at least one first section (13, 34) and at least one second section (14, 35) different from the first section, wherein the at least one first section is arranged for spatially filtering the Raman radiation, and the at least one second section is arranged for imaging the spatially filtered Raman radiation onto the detector device, and for receiving the chemiluminescence and imaging the chemiluminescence onto the detector device. wherein the second measuring unit (46) is arranged between the first measuring unit (2) and the detector device (29, 43), and wherein the detector device is arranged at one end of the second section facing away from the first measuring unit (2), and within the second section, the second measuring unit (46) is implemented at one end of the second section facing the first section.

2. The method according to claim 1, wherein, The first component is nitrogen dioxide.

3. The method according to claim 1 or 2, wherein The reactant includes ozone and / or the second component is nitric oxide.

4. The method according to claim 1 or 2, wherein A first bandpass filter (20, 40) is used for measuring the first light emission line (15, 45) and / or a second bandpass filter (22) is used for measuring the second light emission line (47).

5. The method according to claim 1 or 2, wherein The first light emission line (15, 45) includes a light emission line (15) of the first component and a light emission line (45) of another component different from the first component.

6. A measuring device for measuring at least two different components of a fluid (3), the measuring device comprising: a first measuring unit (2) and a second measuring unit (46), an excitation device (7), an optical device (12, 33), wherein the optical device is assigned to the first measuring unit and the second measuring unit and has at least one first section and at least one second section different from the first section, and a detector device (29, 43), wherein The first measuring unit (2) is configured such that the fluid (3) can be conveyed to the first measuring unit (2), wherein, the excitation device (7) is assigned to the first measuring unit (2) and the excitation device is arranged to generate a first excitation for exciting a first component of the fluid (3) when the fluid (3) is conveyed to the first measuring unit (2), wherein, the first section is arranged to receive a first light emission line (15, 45) that can be triggered by the first excitation for spatially filtering the first light emission line and guiding the first light emission line in the direction of the detector device (29, 43), wherein the first excitation is a laser excitation and the first light emission line is Raman radiation, wherein, the detector device (29, 43) is assigned to the optical device and the detector device is arranged to measure the Raman radiation, wherein, the second measuring unit (46) is configured such that the fluid (3) can be conveyed to the second measuring unit (46), wherein, when the fluid (3) is conveyed to the second measuring unit (46), in the second measuring unit (46), a second component of the fluid (3) can be excited by a second excitation (47) different from the first excitation (6), wherein the second excitation (47) is effected by metering a reactant that causes chemiluminescence of the second component of the fluid (3), wherein, the second section is arranged to image the spatially filtered Raman radiation onto the detector device, receive the chemiluminescence and guide the chemiluminescence in the direction of the detector device (29, 43), the detector device (29, 43) is arranged to measure the chemiluminescence, and wherein the second measuring unit (46) is arranged between the first measuring unit (2) and the detector device (29, 43), and the detector device is arranged at an end of the second section facing away from the first measuring unit (2), and within the second section, the second measuring unit (46) is implemented at an end of the second section facing the first section.

7. The measuring device according to claim 6, wherein, The second measuring unit (46) has an inlet and an outlet for the fluid (3) and another inlet (52), wherein the reactant (47) can enter the second measuring unit (46) through the another inlet.

8. The measuring device according to claim 6 or 7, wherein, The optical device includes a first receiving optical device (12) and a second receiving optical device (33).

9. The measuring device according to claim 8, wherein, The first excitation (6) excites at least one other component of the fluid (3) different from the first component in the first measuring unit (2) such that the first light emission line (15, 45) includes a light emission line (15) of the first component and a light emission line (45) of the other component, and Assign the second receiving optical device (33) to the first measuring unit (2) and the second receiving optical device is arranged to select the light emission line (45) of the other component and direct the light emission line in the direction of the detector device (43), assign the detector device (43) to the second receiving optical device (33) and the detector device is arranged to measure the light emission line (45) of the other component.

10. The measuring device according to claim 6 or 7, wherein, The optical devices (12, 33) include at least one bandpass filter device (21, 40), wherein the bandpass filter device (21, 40) is configured to select light emission lines specific to fluid components.

11. The measuring device according to claim 6 or 7, wherein, The at least one second section is also arranged to select spatially filtered Raman radiation.

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