• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
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  • 优先权
    • 专利摘要:
    For an apparatus for determining a particle concentration of a sample gas loaded with particles, with which a comprehensive measurement of a particle concentration as well as a time-resolved measurement should be possible in a very simple way in a very large possible measuring range, it is provided that in the measuring instrument ( 1) a Schwärzungszahl- measuring device (12) is arranged for integral measurement and in a measuring volume (8) of a measuring chamber (2), which is arranged upstream of the filter paper (7) of the Schwzahlungzahl-meter (12), in addition a scattered light meter 13 for time resolved measurement is arranged.
    公开号:AT515495A2
    申请号:T50256/2015
    申请日:2015-03-31
    公开日:2015-09-15
    发明作者:Erich Dr Schiefer；Wolfgang Dipl Ing Singer；Wolfgang Dr Schindler
    申请人:Avl List Gmbh；
    IPC主号:
    专利说明:

    Method and device for determining a particle concentration of a sample gas charged with particles
    The subject invention relates to a measuring device for determining a particle concentration in a sample gas loaded with particles, with a measuring chamber into which a supply line for supplying sample gas and a discharge line for discharging the sample gas opens and in the measuring chamber a filter paper is arranged, through which the sample gas flows through in a flow direction and thereby deposit particles on the filter paper. The invention likewise relates to a method for determining a particle concentration of a sample gas charged with particles.
    In order to be able to record the environmental impact of particles contained in the air, a wide variety of measuring instruments are used. The environmental impact can be measured as emissions or immissions. For emission measurement, for example, the exhaust gas of an internal combustion engine, e.g. a motor vehicle, examined according to various criteria. For the measurement of ambient air pollution, locally distributed measuring stations are installed, which also examine the air according to various criteria. A major difference in emission measurement and immission measurement is the respective required measurement range, which may differ by a few orders of magnitude. For immission measurements, the resolution of the instrument must be significantly greater, typically for particle concentrations in the range of mg / m3 to pg / m3, or even ng / m3, than in emission measurements, where resolutions in the range of mg / m3 to g / m3 may suffice ,
    From the prior art a variety of measuring devices are known, which are basically suitable for emission measurement and / or immission measurement. Examples include so-called black smoke meters, scattered light meters or opacimeters, each meter has advantages and disadvantages.
    A blackening number meter is known to measure the deposition of the black portion (carbon content) of a sample gas on a filter paper, e.g. the soot build-up of the soot contained in an exhaust gas. In this case, the filter paper is exposed to exhaust gas (undiluted or diluted) for a while and then the so-called blackening number FSN, which is a measure of the carbon black concentration in weight / volume, e.g. represents mg / m3. With a blackening number meter, however, only an integral measurement is possible in which a measured value is present only after a certain (long) period of time. The better the resolution should be, the bigger the time span will be. A typical value of today's blackening meter has a resolution of approximately 1000pg / m3 / suction time (in seconds). With a required resolution or precision of concentrations of 1 pg / m3, a measured value would therefore only be available every 1000 seconds. A temporal resolution of the measurement, ie a time course of the measured concentration, is not possible here.
    An opacimeter measures the attenuation of light caused by particles in a measuring gas. For this purpose, the measurement gas is irradiated with light and the transmitted light on the opposite side, which is a measure of the particle concentration measured. With an opacimeter, temporally resolved measurements can be performed, but only with low resolution, in the range of 0.1% in opacity (equivalent to about 500 pg / m3).
    A scattered light meter detects the light scattered on particles in a sample gas. For this purpose, the measuring gas is illuminated with light, usually laser light, and the scattered light deflected by the particles is detected by means of detectors. Depending on the number and arrangement of the detectors, it is not only possible to make a statement about a particle concentration in the measurement gas, but under certain circumstances also a statement about the particle size distribution and also about the composition of the particles. Time-resolved measurements in the range of 1 s to about 0.1 ms and also high measured value resolutions in the range of a few 100 mg / m 3 to less than 0.001 pg / m 3 are possible with a scattered light measuring device for the subject application. It should be noted, however, that temporal resolutions up to and including the 1 ns range are generally possible with stray-light gauges of today's technology, but this is not necessary for the objective desired particle analysis in measuring gases. Likewise, with today's scattered-light measuring devices, measured-value resolutions of less than 0.001 pg / m3 can be achieved. Measured value resolutions into the picogram or even the femtogram range are possible here, but this is also unnecessary for the objective desired particle analysis in sample gases, at least from today's perspective. One difficulty of a scattered light meter, however, is the poor calibratability to allow reliably reproducible measurements. In particular, there is still no standard that would ensure reliable calibration.
    It has already been recognized in AT 002 225 U2 that the advantages of the various measuring devices can be combined if at least one scattered light measuring device is combined with a blackening number measuring device or an opacimeter for the measurement. In this case, the disadvantage of poor calibrability of the scattered light measuring device is eliminated by calibrating the highly dynamic scattered light measured values to the integral measured values obtained according to the other measuring method.
    It is now an object of the present invention to provide a device with which a very large possible measuring range in a simple manner, both an integral measurement of a particle concentration, as well as a temporally resolved measurement is possible.
    This object is achieved according to the invention by an apparatus in which the filter paper divides the measuring chamber into a first measuring volume arranged upstream of the filter paper and into a second measuring volume arranged downstream of the filter paper, and a first light source and a number of scattered light detectors are provided on the measuring device. wherein the first light source irradiates a light beam in the first measurement volume, and detect the number of scattered light detectors scattered light scattered on the particles. Likewise, the object is achieved by a method in which a measuring chamber is divided by a filter paper into an upstream first measuring volume and into a downstream second measuring volume and the first and second measuring volumes are flowed through by the measuring gas, a first light beam is radiated into the first measuring volume and the scattered light scattered on the particles is detected by means of a number of scattered light detectors with a first temporal resolution and particles of the measurement gas are deposited on the filter paper as it flows through the filter paper and the deposited particles are detected at a second temporal resolution, wherein the first temporal resolution is greater is considered the second temporal resolution.
    Such a measuring device, or such a method, is characterized in that the same measuring chamber can be used for all measuring methods implemented therein, resulting in a simple and compact structural design. In addition, only one single sampling point for the sample gas is needed for all measurements. This is made possible in particular because the blackening number meter is combined with a measuring method, here a scattered light meter, which does not influence the measurement by the blackening meter. By this combination, furthermore, the temporal resolution of the integral measurement of the blackening number measuring device is possible in a simple manner, since the scattered light measuring device delivers measured values with a higher temporal resolution than the blackening number measuring device. After the blackening number meter and the scattered light meter together cover a very large measuring range, the meter can record a very wide range of particle concentrations, making the meter equally suitable for both emission and immission measurements. Last but not least, the scattered light meter can also be easily calibrated by means of the integral readings of the blackening meter, which is advantageous for accurate and repeatable measurements.
    If another light detector is arranged in the beam path of the light beam, a further particle concentration measurement signal can also be obtained, either for temporal resolution of the integral measurement of the blackening number meter or for calibration of the measurement results of one of the other measurement methods or simply for verification or improvement the other measurements can be used. It is also possible to use different measuring methods for different measuring gases if the measuring methods are suitable for different measuring gases.
    If a second light source, which illuminates the downstream rear side of the filter paper and a reflection light detector which detects the light of the second light source reflected at the back of the filter paper, is provided on the measuring device in the region of the second measuring volume, can also provide another measuring signal for the second light source Particle concentration can also be obtained, which can also be used either for temporal resolution of the integral measurement of the blackening number meter or to calibrate the measurement results of one of the other measurement methods or just to verify or improve the other measurements. It is also possible to use different measuring methods for different measuring gases if the measuring methods are suitable for different measuring gases.
    The temporal resolution of the integral measured value of the blackening number measuring device is also advantageously achieved with a pressure sensor which detects the negative pressure in the second measuring volume. This additional measurement can also be used to verify or improve the other measurements.
    The subject invention will be explained in more detail below with reference to Figures 1 to 3, which show by way of example, schematically and not by way of limitation advantageous embodiments of the invention. It shows
    1 is a schematic representation of the measuring device according to the invention,
    2 shows a cross section A-A through the measuring device according to the invention and
    3 shows a cross section B-B through the measuring device according to the invention.
    The measuring device 1 according to the invention according to FIG. 1 consists of a closed measuring chamber 2, into which a feed line 3 and a discharge line 4 opens. Via the supply line 3, the measuring device 1, or the measuring chamber 2, is supplied with measuring gas, which was taken at any measuring point 6, and discharged via the discharge line 4 (indicated by the arrows in FIG. 1). Thus, the measuring chamber 2 is flowed through by the supply line 3 to the discharge line 4. For this purpose, in the discharge line 4, a conveyor 5 for the sample gas, e.g. a mammalian pump, arranged to convey the measuring gas in the flow direction through the measuring chamber 2. The conveyor 5 could also be arranged in the supply line 3. The measuring point 6 is e.g. an exhaust pipe of an internal combustion engine is taken from the exhaust gas as the measuring gas for an emission measurement by means of a well-known exhaust gas probe. The exhaust gas can be taken undiluted ent, but can also diluted in front of the meter 1 in a well-known manner and / or otherwise processed (for example, by removal in the sample gas contained volatiles). However, the measuring point 6 can also be the environment of the measuring device 1 if the ambient air is used as the measuring gas for an immission measurement.
    The measuring device 1 also comprises an evaluation unit 20, in which the various measuring signals for determining a particle concentration K are evaluated, as will be described in more detail below.
    In the measuring chamber 2 of the measuring device 1, a filter paper 7 is arranged for the measurement of the blackening number FSN. The filter paper 7 divides the closed interior of the measuring chamber 2 into a first closed measuring volume 8 upstream of the filter paper 7 and into a second closed measuring volume 9 downstream of the filter paper 7. In order to determine the desired flow direction, the feed line 3 opens into the first measuring volume 8 and the discharge line 4 in the second measuring volume 9. The measuring gas supplied to the measuring device 1 is carried out through the filter paper 7, which are deposited in the sample gas particles (eg soot particles) deposited on the filter paper 7. After a certain, predetermined period of time, a feed unit 10 is actuated, with which the particle-loaded section of the endless filter paper 7 is conveyed out of the measuring chamber 2 and at the same time a new unloaded section of the filter paper 7 is conveyed into the measuring chamber 2. Outside the measuring chamber 2, a Schwartzungszahlmesskopf 11 is arranged, with which the density number FSN can be determined as a measure of the particle concentration in the sample gas. For this purpose, it can also be provided that the measurement signal M1 delivered by the blackening number measuring head 11 is forwarded to the evaluation unit 20 in order to determine a particle concentration K. Measuring chamber 2, filter paper 7, feed device 10 and Schwzahlzungszahlmesskopf 11, optionally together with the evaluation unit 20, thereby form a well-known Schwzungungszahl meter 12 from.
    The blackening number meter 12 enables an integral measurement of the particle concentration at which, after a certain loading period, for example every 100 seconds, a measured value for the particle concentration K, e.g. in the form of the density number FSN (which corresponds to an optical absorption coefficient) or as a measured value with the unit weight unit A / unit of volume, e.g. mg / m3 (which in calibrated form corresponds to a mass absorption coefficient).
    In the measuring chamber 2, a scattered light measuring device 13 is additionally arranged in the first measuring volume 8, which is described with reference to FIGS. 1 and 2 (section A-A). This is on
    Measuring device 1, a first light source 14, preferably a laser, arranged, with which a light beam 17 is irradiated into the first measuring volume 8. The first light source 14 may be arranged on the wall of the measuring chamber 2, optionally behind an optical window. On the opposite side a beam sink 15 is preferably arranged in order to prevent any disturbing reflections of the light beam 17 on the wall of the measuring chamber 2. In the first measuring volume 8, preferably on the wall of the measuring chamber 2, optionally behind optical windows, a number of scattered light detectors 16a, 16b, preferably two or more, arranged spatially distributed. The light beam 17 is deflected at particles P contained in the measuring gas 8 flowing through the measuring volume 8, and the scattered light 18 produced thereby is detected by the scattered light detectors 16a, 16b. The scattered light 18 is a measure of the particle concentration in the measurement gas. The measurement signal Ma, Mb detected by the scattered light detectors 16a, 16b is forwarded to the evaluation unit 20 in order to determine therefrom a particle concentration Kzu. By measuring and comparing the measurement signals Ma, Mb at at least two different angles, the mean particle size and the particle size distribution can also be assessed in the evaluation unit 20 in a manner known per se. The scattered light measurement does not affect the measurement gas and the particles P therein, which is why the scattered light meter 13 can be arranged upstream of the blackening number meter 12.
    Instead of the beam sink 15, another light detector 16c could also be provided for a transmissivity measurement, e.g. Also, the opacity O, as another measure of the particle concentration in the sample gas to capture. The measurement signal Mc detected by the further light detector 16c is forwarded to the evaluation unit 20 in order to determine a particle concentration K therefrom. If required, the measurement signal of the light detector 16c can also be used to correct the measurement signals Ma, Mb if the scattered light is attenuated by very high concentrations of particles in the measurement volume itself. The extent of the attenuation detected by the light detector 16c can then be used to correct the measurement signals Ma, Mb, since it can be assumed that the scattered light is also attenuated with the same degree. Accordingly, an opacimeter 26 is formed with the light detector 16c and the light source 14.
    If data about the size and shape of the particles P are required, a polarizer 19 can also be provided in the scattered light measuring device 13 (FIG. 2) or a first light source 14 can be used which can change the polarization of the emitted light beam 17. Due to the polarization direction relative to the arrangement of the scattered light detectors 16a, 16b, the type and shape of the particles can also be discriminated, since e.g. the scattered light intensities when using linearly polarized (or circularly polarized) light in the three spatial directions for approximately spherical (droplets, aerosols) and fractal particles (such as black carbon) are different in the different spatial directions. The polarization can be adjusted or changed as needed by the evaluation unit 20, as indicated in Figure 2.
    The scattered light meter 13 enables high-resolution measurements with a high measured value resolution. With scattered light measuring devices 13 with today's technologies temporal resolutions with more than 100 to 1000 measured values per second are possible and sufficient. Theoretically, much larger temporal resolutions would be possible with a scattered light meter 13, here already measurements with a temporal resolution of 1 ps were known, such high resolutions are not required in the present application. Measured value resolutions of greater than 100 mg / m3 to 0.01 pg / m3 can be achieved. Today's opacimeters typically have time resolutions up to the 100 Hz range (100 readings / s) at readings of 0.01 to 100% opacity (equivalent to particle concentrations of 100pg / m3 to greater than 10000 mg / m3).
    With a measurement signal Ma, Mb of the scattered light meter 13 or the measurement signal Mc of the opacimeter 26, the very precise integral particle concentration measured with the blackening number meter 12 can be resolved in terms of time. For this purpose, the measurement signal Ma, Mb of the scattered light meter 13 or the measurement signal Mc of the opacimeter 26 with a first temporal resolution (number of measurements per second) is detected and the measurement signal M1 of the blackening number meter 12 with a second temporal resolution (number of measurements per second ), wherein the first temporal resolution is greater than the second temporal resolution. After each measuring method has to supply the same particle concentration K for a certain period of time, for example the second temporal resolution, the measuring signals can be related to each other in time, the measuring signal M1 of the blackening number measuring device 12 can be timed by the measuring signals Ma, Mb, Mc of the Scattered light meter 13 or opacimeter 26 are resolved ..
    In the second measuring volume 9 in the measuring chamber 2, a second light source 21, preferably a high-efficiency LED, can be arranged, as shown in FIGS. 1 and 3 (section B-B). The second light source 21 may be arranged in the wall of the measuring chamber 2, optionally behind an optical window. Equivalently, in the wall of the measuring chamber 2, an optical lens 24 may be arranged, which cooperates with a spaced therefrom light source 21 (indicated in Figure 3). The second light source 21 irradiates, possibly via the optical lens 24, the non-particle side of the filter paper 7, ie the clean, downstream rear side of the filter paper 7. The stronger the filter paper 7 fouls during the integral measurement of the blackening meter 12, the more less light from the second light source 21, which illuminates and transmits the filter paper 7, is reflected on and in the filter paper 7. The reflected light is detected with a reflection light detector arranged in the reflection region 22 at certain time intervals and the detected measurement signal M2 is evaluated in the evaluation unit 20. The reflected light can also be collected by a converging lens 25 in the wall of the measuring chamber 2 and forwarded to the reflection light detector 22, as indicated in Figure 3. This also allows a temporal resolution of the intrinsically integral measurement of the blackening number meter 12, since from the time change of the measured value of the reflection light detector 22 (measuring signal M2) on the admission of the filter paper 7 with particles P in the respective time interval can be concluded.
    If the particles P deposit on and also in the filter paper 7, steadily less reflected light will reach the reflection light detector 22. The detected in the reflection light detector 22 measurement signal M2 is temporally resolvable in the given configuration. The time integral of this measurement in the reflection light detector 22 must, however, by definition coincide with the time integral of the measurement with the blackening number meter 12, so that a correspondingly more precise calibration is possible since the measured value of the blackening number meter 12 can be verified. The disadvantage, however, is that the measured value resolution with the reflection light detector 22 moves only in the range of the opacity measurement. In contrast to the scattered light measurement with the scattered light meter 13, therefore, with the reflected light detector 22, no very large measured value resolution can be achieved. For high particle concentrations, which may well occur in emission measurements, the measurement resolution in the range of more than about 10 mg / m3 may well be sufficient, but the time dynamics of this measurement signal in the range of scattered light measurements of about 100 Hz remains. At particle concentration readings of greater than 100 mg / m3, this measurement method again has advantages over the scattered light measurement, or supplements this since optical self-absorption effects can thus be avoided.
    It should be noted here that the combination of the blackening number measuring device 12 with the second light source 21 for the time resolution of the integral measured value of the blackening number measuring device 12 can also be regarded as inventive in its own right. For the determination of a particle concentration K from the blackening number FSN, the integral suction volume, that is to say the volume of sample gas which flows through the measuring chamber 2 for an integral measured value of the blackening number measuring device 12, is also necessary. The suction volume can be calculated, for example, based on the measured under the filter paper 7 negative pressure. For this, the absolute pressure, the suppression on / after the filter paper 7, the differential pressure caused by the gas flow at a metering orifice and the temperature at the metering or filter paper 7 are required. From this, the integral suction volume can be calculated according to a known formulaic relationship.
    A general and known formula for calculating a volume flow V is shown below:
    With the mass flow M in kg / s and the density p of the medium in kg / m3. The mass flow M results from
    With the differential pressure Δρ at the metering orifice, the absolute pressure p in front of the metering orifice, the absolute temperature T at the metering orifice and a calibration factor k.
    The suction volume in m3 is then given by the integral (or the sum) of the individual temporally resolved measured volume flows V ,, of course for the correct measurement, the time resolution of the individual volume flows V also in the range of the temporal resolution of the determination of the particle concentration K, e.g. in the range of about 100 Hz, must be.
    It can be measured in the measuring device 1 but also the suppression downstream of the filter paper 7, ie in the second measuring volume 9, with a pressure sensor 23. It has been found that the suppression changes with the retention of the suction volume with the deposition of particles P on the filter paper 7. With increasing deposition or longer loading time of the filter paper 7 and the negative pressure increases. Thus, the time profile of the negative pressure (measurement signal M3) can be used to time-dissolve the intrinsically integral measurement of the blackening number meter 12. This evaluation method is equivalent to the method with the reflected light on the filter paper 7 of the second light source 21 and the reflection light detector 22, with the difference that here not the change of the diffusely reflected light but the change in the differential pressure before and after the filter paper 7, caused by the particle deposits , currently resolved measurement of the amount of deposited particles can be used. The resolution of this method is about the same as with the optical reflection method with the second light source 21 and the reflection light detector 22.
    It should be noted here that the combination of the blackening number measuring device 12 with the detection of the negative pressure for the time resolution of the integral measured value of the blackening number measuring device 12 can also be regarded as inventive in its own right.
    An emission or immission measurement can now proceed in such a way that an integral measurement of the particle concentration K is carried out with the blackening number meter 12. The scattered light meter 13 can be used to measure very low particle concentrations (in mg / m3 down to the low μg / m3 and ng / m3 range), but can also be used to time the integral measurement of the blackening meter 12 dissolve. The readings of the scattered light meter 13 may also be calibrated to the integral measurement of the blackening meter 12, e.g. as described in AT 002 225 U2. For low particle concentrations K, the measured values of the scattered light measuring device 13 can also be used directly in order to avoid necessary long loading times in the blackening number measuring device 12. However, it is also possible to use a second light source 21 and the evaluation of the reflection at the rear side of the filter paper 7 and / or the measurement of the negative pressure in the measuring volume 9 in order to temporally resolve the integral measurement of the blackening number measuring device 12. Using multiple temporal resolution methods of the integral measurement of the blackening meter 12, the accuracy of the temporal resolution can be determined by statistical methods, such as e.g. Averaging, can be improved or a possible susceptibility of a particular method to external influences or on the nature of the particle or particle composition can be compensated. In order to obtain with the measuring device 1 at a certain time interval with the Schwzungzungszahl meter 12 a very accurate integral measurement of the particle concentration K, which can also be temporally resolved (particle concentration K (t)) using the methods described above. For this purpose, very low particle concentrations K can also be measured with the scattered light measuring device 13.
    In addition, the integral measurement can also be used to calibrate the time resolved measurements. For this purpose, a defined calibration gas could be supplied to the measuring device 1 and one or more integral measurements (blackening number measuring device 12) could be carried out, to which the other measuring methods are calibrated. This is possible because the different measurement methods must provide the same measurement results for a specific time range. As the calibration gas, e.g. a gas generated by a particle generator and containing a known particle concentration.
    However, in order to enable the described mutual calibration in the measuring device 1, it is necessary to calibrate at least the blackening number measuring device 12 or opacimeter 26 or scattered light measuring device 13 contained in the measuring device 1. Various calibration methods are conceivable here.
    For example, it would be possible to calibrate for the optical absorption of the particles to be measured. For this purpose, the optical absorption of a defined calibration gas can be measured for calibration. The optical absorption is known to follow the Lambert-Beer law in the form I (L) = I0 -e μί. Here l0 is the emitted light intensity and μ is the absorption coefficient of the medium (in this case the calibration gas). The distance L is a given device parameter. If a defined calibration gas is supplied to the measuring device 1 and measured with the opacimeter 26 and / or scattered light measuring device 13, the respective measured measurement signal Ma, Mb, Mc can be calibrated by the Lambert-Beer law. For a real measurement on a measuring gas, only the changed absorption coefficient μ of the measuring gas is to be converted in the measuring device 1. For this purpose, the absorption coefficient μ of the measuring gas can be adjustable on the measuring device, e.g. via an appropriate input option on the evaluation unit 20. To support in the measuring device 1 also references known absorption coefficient μ different measuring gases or Meßgaszusammensetzungen (type, size, distribution of the particles contained) be deposited. Optionally, the absorption coefficient μ of the measuring gas can also be otherwise, outside the measuring device 1, e.g. in a corresponding laboratory.
    Although Lambert-Beer's law does not apply to the blackening meter 12, it does have a similar relationship. In particular, there is also a parameter which depends on the respective medium. For calibrating the blackening number measuring device 12, the statements made above on the opacimeter 26 and the scattered light measuring device 13 are therefore essentially analogous.
    Alternatively or additionally, the calibration can also be carried out on the particle mass concentration. For this purpose, a defined calibration standard, such as a CAST (Combustion Aerosol Standard), with a defined particle mass concentration can be used. The measurements with the blackening number meter 12 or opacimeter 26 or scattered light meter 13 can then be referenced to the calibration standard and thus calibrated.
    Here it is also possible to calibrate to the sample gas. For this purpose, the measurement gas outside of the measuring device 1 must be examined in order to determine a particle mass concentration of the measuring gas. For this purpose, the sample gas can be filtered and the filtered material can be examined. This can be done, for example, by gravimetric measurement of the filtered material, if the type of particle is known, e.g. Soot in an exhaust. But it is also a detailed chemical analysis of the filtered material (for example, to determine the composition of the particles, the proportions of graphitic and non-graphitic or amorphous carbon and the proportions of various hydrocarbon substances and subsequently also their compositions) possible.
    The absorption coefficient μ can also be represented by the formula μ = Q * p, with the absorption cross-section Q [m2 / g] of the substance to be measured and p its density [g / m3].
    A measuring device may now be tested for a calibration concentration of a known particle concentration K and the absorption cross-section Q for that calibration gas, which may be known or determined (measured or calculated) from physical or chemical analysis. be calibrated mg / m3.
    The particle concentration K of a substance to be measured thus results from the above relationship for the absorption coefficient μ
    with a calibration factor F or also a calibration function FK (both dimensionless). The absorption cross section Q is thus considered as part of the calibration function FK or the calibration factor F and is constant at the predetermined calibration points. This is correct for gases, solids, liquids such as propane, quartz or water (under otherwise constant conditions of especially temperature T and absolute pressure Pa and partial pressure Pp), as long as this substance is not chemically reacted, adsorbed, dissociated, dissolved, etc. Usually, the remaining dependence of the calibration function (in particular of temperature T, absolute pressure Pa and partial pressure Pp) in a linearization curve of the various particle analyzers (density meter 12, opacimeter 26, scattered light meter 13) will be taken into account in the meter 1, so that only the calibration of the zero point and another calibration point is required. Cross sensitivities of foreign substances are almost completely avoided by the choice of measuring ranges. However, for measurements of carbon black particles from carbon black emissions, the above assumption is not valid because the absorption cross section Q of the carbon or carbonaceous particles is variable. In the actual chemical sense, such carbon or carbonaceous particles are not a homogeneous chemical substance, such as e.g. Water, but are composed of a more or less variable conglomerate of substances, the majority of which are aggregate forms of more or less black carbon. Typically, the absorption cross-section Q may vary in the visible range of eye sensitivity in the range of <2 to> 16, with diamond as the extreme form of the carbons having an absorption cross-section Q of about 0, while the absorption cross-section Q of pure amorphous carbon is typically in the range of approx. 8 m2 / g. Composite particles of amorphous carbon with attached transparent components (typically in the range of more than 80% of the mass) may also have absorption cross-sections Q of> 16, since here the light is focused by optical effects on the black carbon core and thus the absorption becomes higher can, as without transparent components.
    In normal usage, however, the term "black carbon" is understood to mean only particles which have an absorption cross-section Q of at least more than 4 m 2 / q, in real terms
    Measurements could be found, however, that quite often values of less than 4 m2 / g have occurred.
    The absorption cross section Q of the calibration gas used (particle-laden gas of known composition and concentration) can be stored in the measuring device 1 as an additional calibration parameter Qk together with the calibration factor Fk (or the calibration function F).
    If a measuring gas with an absorption cross-section Qg deviating from the calibration gas is to be analyzed in the measuring device 1, the calibration with the calibration gas is still valid. It is only necessary to communicate the absorption cross section QG of the gas to be analyzed to the measuring device 1, e.g. via a corresponding input possibility on the measuring device 1, and the measured value output of the particle concentration in weight / volume mg / m3 can be determined according to the relationship
    automatically to the sample gas to be adjusted. Thus, the variability in the composition of the particles and thus also of the absorption cross section Q of the different types of particles in the calibration of the measuring device 1, or one of the particle analyzers contained therein, flow.
    权利要求:
    Claims (9)
    [1]
    1. Measuring device for determining a particle concentration (K) in a loaded with particles (P) measuring gas, with a measuring chamber (2) into which a feed line (3) for supplying sample gas and a discharge line (4) for discharging the sample gas opens and in the measuring chamber (2) a filter paper (7) is arranged, through which the sample gas flows in a flow direction and thereby particles (P) on the filter paper (7) deposit, characterized in that the filter paper (7) the measuring chamber (2 ) in a first, upstream of the filter paper (7) arranged measuring volume (8) and in a second, downstream of the filter paper (7) arranged measuring volume (9) divides, and the measuring device (2) a first light source (14) and a number of Scattered light detectors (16a, 16b) are provided, wherein the first light source (14) irradiates a light beam (17) in the first measurement volume (8), and the number of scattered light detectors (16a, 16b) scattered on the particles (P) it detect stray light (18).
    [2]
    2. Measuring device according to claim 1, characterized in that on the measuring device (1) in the beam path of the light beam (17), a further light detector (16c) is arranged.
    [3]
    3. A measuring device according to claim 1, characterized in that on the measuring device (1) in the region of the second measuring volume (9), a second light source (21) is provided which illuminates the downstream rear side of the filter paper (7), and a reflection light detector (22 ) is provided, which detects the light of the second light source (21) reflected at the rear side of the filter paper (7).
    [4]
    4. A meter according to claim 1, characterized in that the measuring device (1) in the region of the second measuring volume (9), a pressure sensor (23) is provided which detects the negative pressure in the second measuring volume (9).
    [5]
    5. A method for determining a particle concentration (K) of a sample gas charged with particles (P), in which a measuring chamber (2) through a filter paper (7) into an upstream first measuring volume (8) and into a downstream second measuring volume (9 ) is divided and the first measurement volume (8) and second measurement volume (9) is flowed through by the measurement gas, a first light beam (17) is irradiated in the first measurement volume (8) and scattered by the particles (P) scattered light (18) by means of a number of scattered-light detectors (16a, 16b) is detected at a first temporal resolution, as particles (P) of the measurement gas flow through the filter paper (7) are deposited on the filter paper (7) and the deposited particles are detected at a second temporal resolution, wherein the first temporal resolution is greater than the second temporal resolution.
    [6]
    6. The method according to claim 5, characterized in that the particle (P) attenuated in the measuring gas light beam (18) with a light detector (16c) is detected.
    [7]
    7. The method according to claim 5, characterized in that with a second light beam, the downstream rear side of the filter paper (7) is illuminated and the light reflected on the filter paper (7) light with a reflection light detector (22) is detected, wherein the temporal resolution of the reflection light detector (22) is greater than the second temporal resolution.
    [8]
    8. The method according to claim 5, characterized in that the negative pressure in the second measuring volume (9) with a temporal resolution which is greater than the second temporal resolution, is detected.
    [9]
    9. The method according to any one of claims 5 to 8, characterized in that the measurement is calibrated with the greater temporal resolution by means of the measurement with the smaller temporal resolution.
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    引用文献:
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    JP5166208B2|2008-10-28|2013-03-21|シスメックス株式会社|Sample analyzer, calibration method for sample analyzer, and computer program|
    法律状态:
    2021-11-15| MM01| Lapse because of not paying annual fees|Effective date: 20210331 |
    优先权:
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    ATA50256/2015A|AT515495B1|2015-03-31|2015-03-31|Method and device for determining a particle concentration of a sample gas charged with particles|ATA50256/2015A| AT515495B1|2015-03-31|2015-03-31|Method and device for determining a particle concentration of a sample gas charged with particles|
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