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    • 专利摘要:
    The invention relates to a method and a device for determining the CO 2 content (CCO 2) in a liquid to be tested, in particular in a beverage, wherein the measurement of the absorption of the liquid to be measured at at least one wavelength (ACO 2) is within a first wavelength range between 4200 and 4300 nm is carried out and a first absorption value (ACO2) is measured by means of the attenuated total reflection (ATR) method, - wherein the measurement of the absorption of the liquid to be measured at at least one second wavelength (Aref) within a second wavelength range between 3950 and 4050 nm is performed and a second absorption value (Aref) by means of the method of attenuated total reflection (ATR) is measured. According to the invention, it is provided that measurement of the absorption of the liquid to be measured is additionally carried out at at least one third wavelength (An) within a third wavelength range between 3300 and 3900 nm, and a third absorption value (An) by means of the attenuated total reflection method (ATR ) - that a given model function (M) is used for determining the CO 2 content (CCO 2) on the basis of the first, second and third absorption values, and - that the model function (M) is based on the determined first, second and third absorption values (ACO2, Aref, An) is applied and the result of the evaluation as C02 content (CCO2) of the liquid to be tested is available.
    公开号:AT512291A4
    申请号:T2112012
    申请日:2012-02-20
    公开日:2013-07-15
    发明作者:
    申请人:Anton Paar Gmbh；
    IPC主号:
    专利说明:

    1 * · «« t * · ·
    The invention relates to a method for determining the content of C02 in a liquid to be tested according to the preamble of independent claim 1. Furthermore, the invention relates to a device for determining the C02 content in a liquid to be tested according to the preamble of independent claim 7. Advantageously According to the invention, methods and devices for determining the CO 2 content in the quality control of beverages are used.
    However, the scope of the invention is not limited to the quality control of beverages. The exact knowledge of the dissolved components or components of a liquid to be tested and their respective content in the respective liquid is required in many production areas such as biotechnology, in the examination of blood and urine, etc. Interfering components are, for example, carbon dioxide, methanol, ethanol, methane and other chemical substances contained in the liquid, for example in an aqueous solution. An essential requirement of quality control is, above all, that the processes should be controllable in real time. The measurements for this purpose should therefore be close to production, preferably inline, and be feasible even in harsh environments.
    From the prior art, a variety of methods for determining the concentration of ingredients in liquids are known, which are presented in part in the following.
    Chemically reactive substances are often detected by secondary effects such as reaction with acids or luminescence quenching. Such methods are not available for chemically inactive substances such as CO 2. One way to determine the content of chemically inactive gases is the separation of the dissolved gas to be measured by outgassing in a separated by a permeable membrane measuring space and subsequent infrared measurement of the gas, as disclosed for example in the patent EP 1 630 543. However, such variants are only conditionally suitable for a real-time application, the use in an inline measuring method can thus be realized only with great effort.
    In addition, various physical detection methods are common for the determination of the C02 content, for example, manometric methods. Especially in the brewing industry, the volume expansion method is used, which involves the simultaneous measurement of several different dissolved gases on the basis of the measured 2 * * ···································································.
    Pressure and temperature values possible. This process is explained in detail in the patent AT 409 673.
    Another method is based on the evaluation of absorption or
    Transmission spectra in which the excitation of characteristic
    Molecular vibrations, these are rotation and / or vibration, in which liquid leads to an energy absorption and thus a change of intensity in the exciting spectrum. With this method ingredients of low and lowest concentration can be determined, from the absorption of infrared radiation, the respective concentration of the ingredient in solid, liquid or gaseous media is determined. Depending on the measuring task, different wavelength ranges of the spectrum are used for structure elucidation; the measuring range extends from UV / VIS to the infrared range. From the absorption of radiation of certain energy can be deduced the excited molecular or lattice vibrations and thus the components of the material under investigation. For the measuring radiation sufficiently permeable substances can be measured in transmission, for opaque solids and for strongly colored solutions, the investigation of the reflection is known as for example with the method of attenuated total reflection (ATR). In process analysis, the applicability of transmission measurements is often limited by the strong absorption by water molecules in the infrared range, so that reflection measurements such as the ATR method are advantageously used. The spectroscopic determination also shows the advantage that the measurement results are independent of the pressure of the liquid under investigation as well as their components.
    The investigated infrared spectra can thus be used for structure elucidation. If the composition of the liquid under investigation is known, the concentration of the components investigated in the liquid can also be determined. If the fluids under investigation have too high absorption values in order to obtain a usable signal, the principle of attenuated total reflection (ATR) is frequently used. In the infrared range, there are several candidate absorption bands that can be assigned to the C02 vibrations. For example, dissolved CO 2 has a characteristic absorption band in the range around 4.3 μm, which is largely independent of the components occurring in commonly examined beverage samples.
    The technique of ATR, also known as multiple internal reflection, has been used for many years for analysis purposes. In the ATR-3 »*« * · ··
    Spectroscopy exploits the effect of totally reflecting a light beam at the interface between an optically denser medium of refractive index m and an optically thinner medium of refractive index n2 (ni> n2) when the angle of incidence of the light beam toward the interface is the critical angle Θ exceeds total reflection. For the critical angle Θ the following applies: sin (B) = At the interface, the light beam exits into the optically thinner medium and interacts with it. Behind the reflecting surface, the so-called evanescent wave forms with a penetration depth dp in the region of the wavelength λ. The penetration depth dp depends on the two refractive indices ^ and n2, the wavelength λ used and the angle of incidence Θ. λ v 2 π ^ jn · sin2 (β) - n
    If the optically thinner medium absorbs the penetrating radiation, the totally reflected beam is weakened. The absorption is therefore dependent on the wavelength λ and the spectrum of the totally reflected radiation can be used analogously to the transmission measurement for the spectroscopic evaluation. From the transmission or extinction spectrum can be concluded that the composition of the optically thinner medium.
    It is generally known to use absorption spectra for the purpose of detecting ingredients in liquids as well as for the characterization of liquid mixtures, wherein ingredients are detectable and quantifiable even at very low concentrations. In this case, use is made of the fact that molecules are set in vibration by infrared radiation of selected wavelength; dissolved CO 2, for example, has a characteristic absorption band in the region around 4.3 μm. Lambert-Beer's law allows absorption to be translated into precise concentration measurements. It describes
    where Ελ corresponds to the extinction, I the intensity of the transmitted light, l0 the intensity of the incident light, sxthe extinction coefficient, c concentration of the dissolved CO 2 and d the layer thickness of the irradiated body / fluid medium.
    The heart of the ATR sensor is an ATR reflection element that is transparent to the measuring radiation in the region of interest and has a high refractive index. Known materials for ATR reflection elements are, for example, sapphire, ZnSe, Ge, Sl, thallium bromide, YAG (yttrium aluminum garnet Y3AI5012), spinel (MgAl204), etc. Frequently, these reflection elements are designed so that at the interface with the liquid increases the interaction length by multiple reflections becomes. Further elements are one or more radiation sources of suitable frequency (ranges), optionally with means for frequency selection, and one or more detectors, these too may be frequency-selective.
    In the simplest form, an ATR sensor includes an ATR reflection element that allows for internal reflections, a radiation source, and a detection unit. The ATR reflection element projects into a liquid to be examined, either directly into the process stream or into the substance to be investigated in a container. Frequently, a second frequency is examined to refer to the absorption of the solvent. This occurs either by suitable means for frequency selection (eg variable filters) or divided filter areas at the detector or by a second arrangement of source and detector on the same ATR reflection element. The reflection element is pressed tightly against the housing and hermetically sealed, with different sealing materials depending on the required chemical resistance and compressive strength find use.
    It is known from the prior art that such optical measuring systems for process monitoring are respectively adapted to the liquids to be examined. The actual absorption values determined on the ATR sensor are converted into concentrations by selecting a calibration model adapted to the respective liquid, a large number of known variables influencing the measurement being taken into account during the calibration. On the basis of calibration curves measured on known compositions, the measured absorption values are converted into actual concentration values according to the laws described above.
    According to Lambert-Beer's law, the actual absorbed intensity depends on the wavelength-dependent extinction coefficient as well as on the concentration c of the absorbing component and the layer thickness d of the irradiated body. In ATR geometry, however, the layer thickness of the investigated solution is determined by the penetration depth dp of the evanescent wave. How deeply this penetrates into the optically thinner medium depends, in accordance with the laws for total reflection, on the refractive index of the reflection element and on the respective liquid.
    The refractive index of the solution thus plays a role in the determination of CO 2 in beverages insofar as the penetration depth of the ATR beam and thus also the absorption of the beam depends substantially on the ratio of the refractive indices of the ATR reflection element and the liquid to be tested. This refractive index of the liquid to be tested is for the most part predominantly determined by the sugar, extract and / or alcohol content of the liquid, so that the type of liquid itself has a significant influence on the absorption of the ATR jet.
    Due to the different refractive index of liquids to be examined and the resulting absorption there is thus the problem that in each case different calibration models must be found for each different liquid in order to enable a determination of the CCV content. For each fluid, a calibration model must be found separately.
    If, for example, a bottling plant is used for a large number of different liquids, there is the problem that, when changing the liquid to be filled, in each case a calibration has to be carried out or at least the respective calibration model has to be changed by hand. This can lead to problems, in particular in the rapid change between individual liquids or in the case of very large plants with many liquids filled at the same time, especially if the respective liquid is selected incorrectly.
    The object of the invention is thus to overcome the above-mentioned problems and to determine the CO 2 concentration independently of a preset calibration model specially matched to the respective fluid and thus to avoid an error-prone preselection of the respective fluid. The measurement and evaluation of the measured values should thus be carried out independently of a possible preselection of the liquid, error influences due to incorrect model selection and / or changing product compositions should be avoided.
    The invention solves this problem in a method of the type mentioned above with the characterizing features of claim 1. 6 6 ·· ···· · «· · · ·« ··· ···· m ··· »· · · ··· »·« II «♦ · f I» · · · · · · II ·· IM ·· IM I · *
    According to the invention, in a method for determining the CO 2 content in a liquid to be tested, in particular in a beverage, the measurement of the absorption of the liquid to be measured is carried out at at least one wavelength within a first wavelength range between 4200 and 4300 nm and a first absorption value is measured by the method of attenuated total reflection, wherein the measurement of the absorption of the liquid to be measured at least a second wavelength within a second wavelength range between 3950 and 4050 nm is performed and a second absorption value is measured by means of the attenuated total reflection method, provided that the measurement of the absorption of the liquid to be measured is additionally carried out at at least one third wavelength within a third wavelength range between 3300 and 3900 nm, and a third absorption value by means of the method of attenuated total reflection is measured, that a given model function is used for determining the CO 2 content on the basis of the first, second and third absorption value, and that the model function is applied to the ascertained first, second and third absorption value and the result of the evaluation as CO 2 Content of the liquid to be tested is available. As a result of this procedure, it is no longer necessary to carry out a separate calibration for each liquid to be tested, and it is no longer necessary to make any changes to the calibration model between the change of the type of liquid to be tested or to change the calibration model.
    For the numerically stable determination of the CO 2 content and for the simple determination of the respective absorption, it can be provided that the measurement of the first absorption value is carried out by determining the absorbed intensity in a first measuring range which is defined by a first center wavelength in the first wavelength range and a first range width 2MCo2, the first measuring range being in the range of AS> C02 ± Δλ0ω2, and / or the second absorption value being measured by determining the absorbed intensity in a second measuring range which is defined by a second centroid wavelength in the second wavelength range and second range width 2AAref is set, wherein the second measurement range is in the range of ASiref ± ΔΑ, βΐ, and / or that the measurement of the third absorbance value is made by determining the absorbed intensity in a third measurement range determined by e in the third wavelength range lying third center of gravity wavelength and a third range width 2Δλ "is set, wherein the third measuring range in the range of As> n 7 7 ·· · ♦ · ·· ♦ ·· * * · ··· ···· + · • · * Α · · · Α Α Α Α Α Α Α Α Α Α Α Α Α Α Α Α Α Α Α Α / or second and / or third region width in each case in a range between 20 nm and 200 nm, in particular at 100 nm.
    Alternatively it can be provided for the same purpose that the first absorption value, preferably exclusively, at a predetermined in the first wavelength range lying first wavelength, preferably 4260 nm, is determined, and / or that the second absorption value, preferably exclusively, at a predetermined in the second Wavelength range lying second wavelength, preferably of 4020 nm, is determined, and / or that the third absorption value, preferably exclusively, at a predetermined lying in the third wavelength range third wavelength, preferably 3800 nm, is determined.
    In order to better take into account the influences of the temperature on the absorption, it can be provided that, in addition to the determination of the first, second and third absorption value, the temperature of the liquid to be tested is determined that the model function for determining the CO 2 content next to the first , second and third absorption value and the temperature of the liquid to be tested, and that the model function is applied to the determined first, second and third absorption value and the determined temperature and the result of the evaluation as C02 content of the liquid to be tested available becomes.
    For calibration and for determining an advantageous model function, provision can be made for a model function to be created and made available for the determination of the CO 2 content by determining a plurality of reference measurements of the first, second and third absorption values for the CO 2 content different reference liquids with known CO 2 content with different, optionally known refractive index, carried out by means of a fitting method, the model function of the form M = M (Aco2, Af, f ","-ι, ..., Bn) created is adjusted, wherein previously unknown model parameters to the respective predetermined C02 content and the determined first, second and third absorption values, so that when applying the model function on the first, second and third absorption values, respectively, at least approximately, the known C02 Geha! t receives.
    In order to be able to take into account the influences of the temperature, it can be provided that, in the case of the multiplicity of reference measurements, in each case, next to the first, second, and * * * · ♦ ····················································. And the third absorption value, the temperature of the respective reference liquid is also determined, by means of a fitting method the model function of the form M = M (Aco2, A, ef, At, T, Ci, Cn) is created, whereby previously unknown model parameters are adapted to the respective predetermined C02 content, the determined first, second and third absorption values and the respective temperature, so that when applying the model function on the first, second and third absorption values and the temperature in each case, at least approximately, receives the known CO 2 content.
    The invention solves this problem in a method of the type mentioned above with the characterizing features of claim 7.
    According to the invention, in a device for determining the CO 2 content in a liquid to be tested, comprising a first ATR measuring unit for determining a first absorption value at at least one first wavelength within a first wavelength range between 4200 and 4300 nm, a second ATR measuring unit for determining a second absorption value at at least one second wavelength within a second wavelength range between 3950 and 4050 nm, provided: a third ATR measuring unit for determining a third absorption value at an at least third wavelength within a third wavelength range between 3300 and 3900 nm, and an evaluation unit downstream of the ATR measuring units and to which the results of the ATR measuring units are fed, wherein the evaluation unit applies a model function to the first, second and third absorption values and the result of the evaluation at its output as CO 2 content the fluid to be tested is available.
    For the numerically stable determination of the CO 2 content, it may be provided that the ATR measuring units are sensitive in a first, second and third measuring range for determining the absorbed intensity, wherein the first measuring range is defined by a first centroid wavelength lying in the first wavelength range and a first range width 2AAC02, and the first measuring range is set in the range of As, co2 ± Δλςο2, and / or wherein the second measuring range is defined by a second centroid wavelength in the second wavelength range and a second range width 2AAref, and the second measuring range is in the range of ΔFiref + AAref, and / or wherein the third measuring range is defined by a third centroid wavelength lying in the third wavelength range and a third
    9 · · · »»
    Range width 2Δλη is fixed, and the third measuring range is set in the range of λ5, η ± Δλη, wherein the first and / or second and / or third range width is in each case in a range between 20 nm and 200 nm, in particular at 100 nm.
    In order better to be able to take into account the influences of the temperature on the absorption and thus on the determined CO 2 content, a temperature sensor upstream of the evaluation unit can be provided for determining the temperature of the liquid to be tested, wherein the evaluation unit has a model function on the first, second and third Absorption value as well as applied to the temperature detected by the temperature sensor and keeps the result of the evaluation at its output as CO ^ content of the liquid to be tested available.
    For advantageous storage or forwarding of the liquid to be tested during the quality inspection, a container for storage or passage of the liquid to be tested, be provided, wherein the sensitive surface parts of the ATR measuring units and optionally also of the temperature sensor when filling or flowing through the container with the to be tested Liquid contact with this and are arranged in particular in the interior of the vessel.
    In order to be able to retrieve the calibration model quickly and to be able to apply it to the determined measured values, it can be provided that memories are provided for given coefficients in the evaluation unit, and that the evaluation unit has an arithmetic unit which stores the stored coefficients as well as the first, second and third absorption values, and possibly also the determined temperature, are supplied and based on the values supplied to it, the model function evaluates and keeps available at the output of the evaluation unit.
    Advantageous space-saving developments of the invention provide that each ATR measuring unit each comprise an ATR reflection element, an ATR infrared source, and an ATR infrared sensor, or that the ATR measuring units have a common ATR reflection element and a common in the first, second and have an active ATR infrared source and have a common, in the first, second and third wavelength range active ATR infrared sensor, wherein in the beam path between the ATR infrared source and the ATR infrared sensor, an adjustable filter, in particular a filter wheel or a Fabry-Perot Interferometer, is provided, which is permeable depending on its setting in each case only for radiation in the first, second or third wavelength range, or that the ATR measuring units a 10 φφ · «· φ φ φφφφ φ Φ · ΦΦΦ ·« * Φ φφ • φ φ φ φ φφφφ · φφφ φφφ φ φ φφφφ φφφ φ φ φφ φφ · # φφ φφφ φφ common ATR reflection element and a common active in the first, second and third wavelength range ATR infrared source and for the first, second and third wavelength range each separate, located at the end of the respective beam path ATR infrared sensors are provided, or that the ATR measuring units a common ATR reflection element and a common sensitive to all wavelength ranges ATR infrared sensor, and for the first, second and third wavelength ranges each separate, ATR infrared sources are provided.
    A space-optimized embodiment of the invention with a single Reflextionselement provides that the ATR measuring units have at least two separate ATR infrared sources and associated ATR infrared sensors, each having mutually independent beam paths and are different sensitively for each two measuring ranges, each one measuring unit of the first infrared sensor and in each case one measuring unit of the second infrared sensor are sensitive to the same wavelength range and a referencing unit is provided which multiplies the measured value of the third measuring unit by the ratio of the measured values of the two measuring units sensitive to the same wavelength range and keeps it at its output.
    The invention will be explained with reference to a concrete embodiment with the aid of the following drawing figures. Fig. 1 shows an embodiment of a device according to the invention. Fig. 2 shows the structure of an ATR sensor in detail. Fig. 3 shows a preferred ATR sensor in an oblique view. Fig. 4 shows the ATR sensor shown in Fig. 3 in front view. Fig. 5 shows the spectrum of a liquid to be tested. 6 shows schematically spectra of liquids to be tested, each with different CO 2 content and different refractive index referenced to the solvent.
    In the present embodiment shown in Fig. 1 of the invention, the liquid to be tested is passed through a container 6 in the form of a pipeline. At the inner surface of the pipeline, three separate ATR measuring units 1, 2, 3 and a temperature sensor 5 are arranged. The sensitive surface parts 14 (see FIG. 2) of the ATR measuring units 1, 2, 3 are in contact with the liquid conducted through the pipeline. The temperature sensor 5 is located inside the pipeline or at the boundary wall in contact with the liquid of the first of the first half of the seventeenth century.
    Temperature sensor 5 and the ATR measuring units 1, 2, 3 are fed to an evaluation unit 4.
    FIG. 2 shows an ATR measuring unit 1, 2, 3 in detail. The core of the ATR measuring unit 1, 2, 3 is a reflection element 11, which is transparent in the wavelength range of interest for radiation and has a high refractive index.
    These elements may be, for example, a prism, a special ATR crystal, an optical fiber, etc. Known materials for such optical elements are, for example, sapphire, ZnSe, Ge, Sl, thallium bromide, YAG and spinel, etc. Frequently, the reflection elements 11 are designed such that the intensity yield is increased in their interior via multiple reflections. Furthermore, the ATR measuring unit 1, 2, 3 comprises a radiation source 12 in the respective frequency range and a detector 13. At the output of the detector 13 is in each case a measurement signal, which corresponds to the intensity determined by the detector 13. Any frequency-selective means in the beam path between the source and the detector determine the measuring wavelength λ or the measuring range As ± ΔΑ around the center of gravity wavelength As of the ATR measuring unit.
    Each of the ATR measuring units 1, 2, 3 is surrounded in the present embodiment by a housing 16 which defines a housing interior 15 in which the reflection element 11, the radiation source 12 and the detector 13 are arranged. The sensitive surface part 14 of the reflection element 11 continues the outer wall of the housing 16 with respect to the liquid to be tested and is in contact with the liquid to be tested. The reflection element 11 is pressed tight against the housing 16 or connected to this pressure and gas-tight, for example via an O-ring or by means of soldered joints or by inelastic seals, such as PEEK or TEFLON.
    Alternatively, the individual ATR measuring units 1, 2, 3 may be integrated in a common housing 16 and have a common reflection element 11 and in particular also a common radiation source 12 or a common detector 13. Here, the embodiments shown below have proven to be expedient:
    In a first alternative, the ATR measuring units 1,2,3 have a common ATR reflection element 11 and a common in the first, second and third
    Wavelength range active ATR infrared source 12 on. Furthermore, the ATR measuring units 1, 2, 3 also have a common ATR infrared sensor active in the first, second and third wavelength ranges. In the beam path between the infrared source 11 and the infrared sensor 12, an adjustable filter with adjustable filter characteristic is arranged. Such a filter is advantageously designed in the form of a filter wheel having filters with different filter characteristics at different circumferential areas. The filter wheel is rotated by a motor, so that depending on the setting of the filter wheel predetermined circumferential region with its respective filter characteristic is in the beam path. Each peripheral region has a filter, which is permeable only in the first, second or third wavelength range, so that, depending on the setting of the filter, the ATR measuring unit 1, 2, 3 respectively takes measurements of the absorption in the first, second or third wavelength range. Such a filter may also be designed in the manner of a Fabry-Perot interferometer,
    In a second alternative, the ATR measuring units 1, 2, 3 have a common reflection element 11 and a common infrared source 12 active in the first, second and third wavelength ranges. Separate infrared sensors 13 located at the end of the respective beam path are provided for each of the first, second and third wavelength ranges.
    In a third alternative, the ATR measuring units 1, 2, 3 have a common reflection element 11 and a common infrared sensor 13 which is sensitive to all wavelength ranges, separate infrared sources 12 being provided for each of the first, second and third wavelength ranges.
    A further alternative is combinations of the abovementioned structures. For example, an ATR reflection element can be equipped with two detectors and sources in two different wavelength ranges, each of which uses a split filter for additional measurement of another frequency, for example a reference frequency. In this way, different intensities can be normalized to one another even with fluctuations in the source.
    The respective measurement signals of the ATR measurement units 1, 2, 3 and the temperature value T applied to the output of the temperature measurement unit 5 are supplied to evaluation unit 4, which, as described below, determines a value for the CO 2 concentration and at its output for further use available. This value for the CO 2 concentration can be used to adjust the desired concentration by adjusting the CQ 2 feed into the process. Likewise, the value of the CO 2 concentration can be used to redirect and reject parts of the liquid with too high or too low a CO 2 concentration or return them to the production process.
    FIG. 3 shows a preferred embodiment of an ATR sensor with four measuring units 1, 2a, 2b, 3, with which three absorption values ACoz. Aref, to be determined. In this particular embodiment, a single reflection element 11 is provided, wherein two infrared sources 12 are provided, of which the first infrared source 12a emits infrared light in the first and second wavelength range and the second infrared source 12a emits infrared light in the second and third wavelength range. Furthermore, two infrared sensors 13 are provided, of which the first infrared sensor 13a is sensitive in the region of the first and in the region of the second wavelength range and respectively supplies a first absorption value Aco2 in the first and a second absorption value A ^ in the second wavelength range. The second infrared sensor 13b is sensitive in the range of the second and the third wavelength range and provides a second absorption value Aref in the second wavelength range and a third absorption value A "in the third wavelength range. The first infrared sensor 13a and the first infrared source 12a are arranged such that the light of the first infrared source 12a is irradiated to the first infrared sensor 13a. The second infrared sensor 13b and the second infrared source 12b are arranged such that the light of the second infrared source 12b is irradiated to the second infrared sensor 13b. The beam paths of the light beams emitted by the infrared sensors 12a, 12b are normal to each other in the present embodiment, as shown in FIG. Preferably, the measuring ranges of the two filters 17a and 17b are divided. Both enable the determination of two absorption values from A "Aref ACo2 in the respective measuring ranges A s, ref ± A aref, A s, co 2 A AACo 2 and A s, n Α ΔΑ,
    In the present exemplary embodiment, both infrared sensors 13a, 13b each determine a second absorption value Aref. In order to compensate for fluctuations in the brightness of the infrared sources 12a, 12b relative to one another, the ratio between the second absorption value determined by the first infrared sensor 13a and the second absorption value determined by the second infrared sensor 13b is determined. If the second absorption value determined by the second infrared sensor 13b is multiplied by the determined ratio, the second absorption value determined by the first infrared sensor 13a is obtained. So that different illuminance levels by the two infrared sources 12a, 12b have no influence on the ratio of the individual absorption values to one another, the third absorption value determined by the second infrared sensor 13b is multiplied by the determined ratio, and used as the basis for the further calculations.
    FIG. 5 shows a typical spectrum of the absorption coefficient of saturated aqueous CO 2 solution. It can be clearly seen that the absorption in the range of about 4260 nm increases significantly, while CO 2 -free water in this wavelength range does not have an increase in the absorption.
    Fig. 6 shows schematically absorption spectra of four different liquids. Briefly, the individual influences of CO 2 and a substance which raises the refractive index and is dissolved in the respective liquid with a concentration of C 1+, in the present case of sugar, are shown on the absorption spectrum of an ATR measurement. Absorption spectra of the following liquids are shown. C02 [g / l] ^ extract [BRIX] S, 0 0 s2 5 0 s3 5 10 s4 0 10
    Table 1. CO 2 concentration and BRIX of the liquids whose absorption spectra are shown in FIG.
    The absorption spectrum St of a first liquid has a BRIX value of 0 and is free of CO 2, is approximately constant in the wavelength range between 3000 nm and 4500 nm and has referenced to the water background in particular no significant slopes, maxima, minima, etc.
    A second absorption spectrum S2 was prepared for a second liquid which contains no sugar and has a BRIX value of 0 and a content of 5 g / l CO 2. The absorption spectrum S2 of the second liquid has a clear maximum at a wavelength ACo2 of about 4260 nm. Below a wavelength of about 4050 nm, the absorption spectrum S2 of the second liquid corresponds to the absorption spectrum Si of the first liquid.
    A third absorption spectrum S3 was prepared for a third liquid containing sugar and having a BRIX value of 10 and also having a content of 5 g / l of CO 2. In the wavelength range above a wavelength Aret of about 4050 nm, the third absorption spectrum S3 has a similar course to the second absorption spectrum S2, wherein the maximum is likewise in the range of a wavelength Aco2 of about 4260 nm, but more pronounced than in the second absorption spectrum S2, d. H. the absorption is stronger than in the second absorption spectrum S2. Below a wavelength Aref of about 4050 nm, the absorption increases with respect to the first two absorption spectra Si, S2 with decreasing wavelength. At a wavelength A "of about 3800 nm, there is already a clear deviation between the absorption coefficient of the second and the third liquid due to the absorption of the extract.
    The fourth absorption spectrum S4 was prepared for a fourth liquid containing sugar and having a BRIX value of 10, but unlike the third liquid, contains no CO 2. In the range above a wavelength of Aref of about 4050 nm to a wavelength range of about 5000 nm, the absorption spectrum S4 has an approximately parabolic course. In the range below a wavelength of from about 4050 nm to a wavelength range of about 3000 nm, the absorption spectrum S4 of the fourth liquid approximately corresponds to the absorption spectrum S3 of the third liquid.
    It can be seen from the illustrated absorption spectra St, S2l S3, S4 that both the change in the refractive index of the respective liquid and a change in the CO 2 content of the respective liquid have effects on the respective absorption spectrum St, S2, S3, S4 and one measurement alone At the wavelength of the maximum absorption Aco2 and at the wavelength of Are (do not allow a clear determination of the C02 content, since the influence of the refractive index on the respective absorption spectrum leads to falsifications of the result.) From the absorption spectra S3, S4 of the third and fourth liquid however, it can be understood that a correction of the influence of the respective refractive index can be corrected by determining an additional absorption value at a wavelength An in the range of 3300 to 3900 nm.
    Preferably, a measurement of the absorption value is made with the sharpest possible wavelength limitation. The first absorption value Aco2 is determined at a predetermined first wavelength Aco2 (preferably at 4260 nm) lying in the first wavelength range. The second absorption value Aref is determined at a predetermined second wavelength Aref (preferably at 4020 nm) lying in the second wavelength range. The third absorption value A "is determined at a predetermined third wavelength range An (preferably at 3800 nm) lying in the third wavelength range.
    The wavelength-selective means used in the ATR sensors have real finite half-widths. A spectral resolution such as in spectrometers is thus not achievable. The absorbance values measured at the detector therefore always correspond to the integrated intensity over a wavelength range which is characterized by the characteristic of the sensor. The absorption is therefore determined with a specific spectral width ± Δλ about the centroid wavelength λ of the sensor.
    In order to perform an advantageous correction, it is not necessary to determine the absorption at specific fixed wavelengths, but it is sufficient if the focus wavelength of the respective sensor in the respective wavelength ranges, i. the first centroid wavelength ACoz lies in the wavelength range between 4200 and 4300 nm, the second centroid wavelength Arei is in the wavelength range between 3950 nm to 4050 nm and the third centroid wavelength An is in the wavelength range between 3300 and 3900 nm, the respective absorption values Aco2. Aref and An are determined by measuring the integral absorbed intensity in the wavelength range ± Δλ around the respective ones
    Center of gravity wavelengths ACo2. Aref, An measured. Preferably, the spectral width Δλ will be less than ± 50 nm about the centroid length λ.
    Preferably, the individual wavelengths are selected within the predetermined first, second and third wavelength range so that a sufficient signal-to-noise ratio is to be expected for each of the residual substances to be measured in the solution.
    In the following, four exemplary embodiments will be described, how a value cC02 for the CCV concentration is determined from the measured values for the first, second and third absorption values Acc », A ^ f, An and for the temperature T. In the evaluation unit 4, the individual absorption values Aco2, Α, βί, A "and a value for the temperature T are supplied, the value Ccoz for the CO 2 concentration is determined by using a model function M.
    In all embodiments, a formulation is used in which the three absorption values Aco2. A ^ f, A "are each replaced by the following two difference values ADn, ADcoz. The second absorption value A, * becomes at the second wavelength
    Iff are used as the reference value, only the differences from this reference value are used for the further calculations: ADn = A "- Α, βί, ADC02 - Aco2 - A, ef.
    In general, a model function M is defined, which defines the CCV concentration as a function of the two difference values and of the temperature T: cCo2 = M (ADco2, ADn, T).
    Alternative to the two difference values ADco2. ADn also the actual absorption values A, ef, An, Aco2 can be used. The model function then has the following form CC02 = M (Ac02, An, Aref, T).
    Depending on the desired accuracy class, more or less terms may be considered in the respective approximation, the model function being determined in each case by a number of calibration constants. Different model functions, such as a Taylor series development, can be used here to model the relationships and dependencies.
    Based on the considerations of FIG. 6, the effects of different influences on the measured absorption value Aco2 and on the first difference value ADCo2 are shown: The measured absorption value Ac02 depends on the temperature T, on the CO 2 content cC02 and on the refractive index. In the individual exemplary embodiments, the following basic assumptions are made in order to take these dependencies into account mathematically. A modeling of this relationship can be generally made as follows: ADC02~T: For the relationship between the measured absorption value C02 and the temperature T, a linear approach is used. ADCo2 ~ cC02: Different assumptions can be made for the relationship between the first difference value ADC02 and the C02 content; in particular, a linear, polynomial or exponential approach can be used. ADC02~n, ADn, An: In order to take into account the influence of the refractive index n or the third absorption value An or the second difference value AD "on the first absorption value ADC02, a polynomial approach is preferably adopted.
    In the first exemplary embodiment, the temperature T of the liquid is additionally taken into account, since the determined absorption values depend not only on the refractive index but also on the temperature T of the liquid and the temperature T due to their effect on the density of the liquid and on the measuring arrangement itself, for example as a result of the change the beam intensity of the source, effects on the determined absorption values zeitigt. The effects of the temperature T on the differential value ADCo2 are considered linearly in a first approximation. It is assumed that the difference value ADCoz is dependent on the sum of two terms fT {T), fco2 (cco2) which are independent of each other. ADc02 = ZrCO fc02 ^ CC02) = ^ 0 ^ T_ 1 '^ & C02_l * CC02
    Here, some model parameters k0, kT1, kC02j are predefined, which make it possible to adapt the modular function M to the actual measured values. By forming results for the CO 2 concentration cC02 under measurement of temperature T and the first difference value ADC02 cC02, uncorr
    ADco2 ~ kp ~ kr_l 'T kco2jL
    This result does not take into account the influences of the refractive index n on the first difference value ADCo2 and on the first absorption value ACo2. To take account, the uncorrected CC> 2 concentration cCo2, uncorr can be multiplied by a correction term fn (ADn, T) which depends on the second difference value ADn polynomial and on the temperature linearly: fn (ADn, T) = Α * + B '* T + C' * ADn + D '- ADn2 + E' * ADn3 By substituting the correction term fkorr (ADn, T) into
    Cco2 = M (ADco2i ADn, T) = Cc02.unkoir * fn (ADn, T) gives the following relationship: M (ADC02, ADnT) - ccozkorr - = cC02, uncorr (Λ '+ B' T + C 'ADn + D 'AD "+ Ε' · Αθξ + ·)
    In a polynomial development of the correction term with a degree of three, the model has a total of eight model parameters, in the present exemplary embodiment these are A B ', C', D ', E' and k0, kTJ, kC02_i ·
    To determine the model parameters, a number of m measurements of the temperature T and the absorption values A, ef, An, Aco2 of different known
    Liquids with known CO 2 concentrations, each with different extract concentrations or refractive indices each carried out at different temperatures. With a fitting method, model parameters are determined on the basis of the measured values T, Arefs An, Aco2, for which the model function, when applied to the measured values determined, matches the known C02 concentrations as well as possible.
    As an alternative to a fitting method, it goes without saying that the individual model parameters can be determined on the basis of the individual measured values and the known CO 2 concentrations cC02, i, 0002,2. · CCo2im be solved analytically. M (Ti, Afef, · !, An, i, Aco2, I) = CC02.1 M (T2, Afef1, An, 2, Aco2, 2) = CC02.2 M (Tm, Are ^ m, An > m, Aco2, m) - Cc02.m
    A second embodiment of the invention takes into account the changing penetration depth dp of the measuring beam into the liquid to be tested, which results from the different refractive index of the liquid to be tested. These influences are now taken into account by introducing the second difference value ADn = A "- A, ef. If one considers the principal relationships between concentration c, penetration depth dp or examined layer thickness of the evanescent field and the first difference value ADco2 given for the CO 2 measurement, then approximately ADco2-ε 'CC02' dp »where ε is the permeability of the respective liquid for radiation corresponds to the measuring wavelength ACo2. For the individual measurement with the reflection element 11 and the defined beam geometry at a certain wavelength λ, a simple relationship between the refractive index and the penetration depth dp thus results.
    In the third wavelength range λη between 3300 nm to 3900 nm, the absorption ranges of ethanol (alcohol) and different sugars overlap in aqueous solution. These influences are taken into account by measuring the third absorption value An at λη and determining a second difference value ADn between the third and second absorption values: AD "= An-A, ef. 9 /) * * * · · ····· «· f * -V · ·» · · · · · · « «F · * · * ** · * · ** · ♦ * ··« For the second difference value ADn, the following assumption is approximately made, taking also into account the temperature dependence of the measurement signal, resulting in the following relationship: - / r (^) + fex (c extract) - 'Jo + Jt 1' T + Jn 1 'cExtract where Cextrakt indicates the concentration of any dissolved in the liquid extracts such as sugars or alcohols, which contribute to a change in the refractive index of the liquid to be tested , In addition, model parameters j0, j'tj and jnj are also predefined, which make it possible to adapt the respective functions f to the actual measured values. If one converts this relation to c ^ act, one obtains the following connection. ^ Extract ~
    ADn ~ Jo h_ 1 'T
    Jn 1
    The extract concentration CExuaw thus determined is a direct measure of the refractive index of the solution and thus of the penetration depth of the measuring beam into the solution. The extract concentration CextraM is thus available as a correction factor for the determination of CO 2 concentration. The extract concentration CExtract, however, can no longer be considered strictly linear according to the Lambert-Beer law, since this relationship applies only approximately to the absorption by only a single constituent component in the extract. However, since in reality there is a mixture or composition of several extract components and / or alcohol, the mixture is thus no longer a ternary substance mixture, the physical conditions can thus be only approximated.
    The refractive index is defined as the ratio of the propagation speed of the light in the vacuum c to the speed of light in the liquid v and depends directly on the extract concentration of the liquid to be examined, this behavior is also used for example for determining the sugar concentration in solutions by means of refractometers. In addition, due to the further dependencies (molecular weight, polarizability), the refractive index of the substance mixture is not available analytically from the mere measurement of a wavelength. However, the absorbance values measured at a position in the first wavelength range between 3300 nm to 3900 nm are representative of the respective extract and alcohol concentration.
    The penetration depth dp is subsequently modeled in such a way that, depending on the desired accuracy for further consideration, the penetration depth dp or the refractive index n 2f.. · · ······························································································································ For this correction one can now choose, for example, a multi-membered polynomial approach or an exponential approach which corrects the measured CO 2 concentration with the measured extract absorbance.
    For example, using a polynomial approach to the penetration depth dp, dp = A + B 'T + C * ADn + D * AD ^ + E * AD £ + **
    Thus, for the dependence of the measured absorption ADcco of any C02 concentration on the penetration depth dp ADC02 = ε cC02 - dp = ε cCQ2 · (A + B-T + C × ADn + D × AD * + E × AD% +)
    If one transforms this equation to Cco2, one obtains. , AOqq2 CC02 - M (ADC0 2, ADn, T) - € (A + b.t + c, ADn + D, ADz + E, AD3 + ... ^
    A third exemplary embodiment of a model function M takes account of measuring methods in which the first absorption value ADco2 has not been determined at a specific wavelength but as an integrally measured absorption value over a specific wavelength range of about 50 nm to 100 nm. If one chooses to increase the intensities, at the same time using the most favorable components, filters with a larger spectral width, the linear relationship between concentration and intensity of CO 2 absorption, which is basically represented by the Lambert-Beer law no longer applies. Rather, this relationship can be better approximated by an exponential dependency when the transmissivity of the filters used, and hence the integrally measured absorption over a particular wavelength range of about 50 nm to 100 nm, is measured instead of the absorption intensity at a single wavelength masked out of the spectrum. Thus, at about 40 nm half-width of the CO 2 absorption peak, the transmissive spectral wavelength range of the filter is greater than or equal to the actual width of the CO 2 absorption peak.
    «· · · · · · · · · · Tt · ψ 9 • · • ·· ♦♦♦ ψ 9
    or, taking into account the temperature ADc02 - fr (J ") f (.cC02) - ^ 0 ^ Tji '^ ^ C02_l' exP (^ C02_2 * CC02)
    1 cC02, uncorr ~ cC02 ~ j. * KC02_2 If one carries out the refractive index correction analogous to the second embodiment of the invention, one obtains M (ADC0Z, ADnT) = cc02korr = = cC02Ainkorr 04 " + B " T + C " - ADn + D " ADl + E " · AD * + -)
    A fourth embodiment of a model function M takes into account that the individual equations for refractive index, temperature and measured intensities in CO 2 absorption can not be considered independently of one another. The refractive index shows a dispersion behavior dependent on the respective liquid to be examined, likewise the extinction coefficient in the equation varies with the wavelength and temperature T. In order to avoid having to carry out the complex analytical evaluation of the individual equations, the following approach can be simplified:
    On the basis of an empirical curve fit for the CO 2 concentration, the temperature T and the refractive index or thus the penetration depth of the measuring beam are taken into account as a model by varying the constants according to the model. For the exponential approach this means
    Now the dependence on the temperature T and the refractive index in the individual terms Y0l A, and t! are taken into account in each case by a linear approach for the temperature T and a polynomial approach for the refractive index or for the measured absorption as follows: ## EQU3 ## · «· • · · · · · · ♦
    Y0 = Anyo + B71VO * AD "+ C" K0 * AD "+ Aj-y-o + Bj-yo T = Ay0 + Bnyo AD" + Cnro · AD "+ Bjy0 · T Ai = Α, ^ ι + B ^ i · ADn + C ^! · AD ^ + Αι - ^ + Βττ, ι-Τ = A ^ j + Bnj1I · ADn + · AD ^ + By ^ j.T
    tj - Antl + Bntl * ADn + Cnti * AD "+ Aytl + Byti * T = Ati + B ^ y * AD" + Cnti AD "+ Byji * T
    Forming the above equation, the following expression is obtained as model function M. M {ADcm, ADnX) = 'CO 2 = -tylnf4 "™ 2 7 °)
    Ai
    By using a linear approach for the temperature T and a polynomial approach for the refractive index or for the measured absorption results for the model function M, the following relationship
    CC02 - (Ati + Bnti 'ADn + Qntl ADn + Bra T) ln (
    Af> CQ2 ~ (Aro ^ Bnyt) ADli + CnY0ADl * Βτγρ-Τ) ^ Ajd + Bndi'ADn + CiuirADji + BTAiT ', where the following quantities AY0, AAi, At1, BnY0, BnAi, Bnti, CnY0, CnAi, Crti , B ™, BTAi, BTti occur as model parameters.
    The determination of the model parameters takes place, as in the other exemplary embodiments of the invention, by calibration on the basis of known measured values. A number of m measurements of the temperature T and of the absorption values A.sub.f, An, A.sub.co2 of different known liquids with known CO.sub.2 concentrations, each with different extract concentrations or refractive indices, in each case at different temperatures, are determined. Using a fitting method, the measured values T, Aref, An, Aco2 are used to determine model parameters for which the model function, when applied to the measured values obtained, corresponds as well as possible to the known CO 2 concentrations. A system of equations is created which has one equation for each separate measurement. M (Ti, Aref'1, ηη, ι, AcO 2, l) CCCC02.1 M {T2, A | -ef <2, Ani2, AcO 2, 2) = CcO 2, 2 M (Tm, Ayef An, mi AcO 2 , m) = CcQ2, m 24 »« * · · «· t * Μ ··· · # ··· · * ·
    This equation system is approximately solved. In particular, a more accurate result can be achieved by increasing the number of measurements. In the present case, 12 model parameters have to be determined so that at least 12 equations are to be used. In the present case, 18 measurements are made, wherein in each case the temperature T, the refractive index and the previously known COr content are listed in Table 2. T [eC] cco2 [g / i] C Extra kt [BRIX] 0 * 5 1 + 2 0 0 + 5 5.5 * 6.5 0 0 + 5 10 + 11 0 20 * 25 1 +2 0 20 * 25 5.5 * 6.5 0 20 + 25 10 + 11 0 0 + 5 1 * 2 6 + 7 0 + 5 5.5 * 6.5 6 * 7 0 + 5 10 + 11 6 + 7 20 + 25 1 + 2 6 + 7 20 * 25 5.5 * 6.5 6 + 7 20 + 25 10 + 11 6 + 7 0 + 5 1 + 2 14 + 15 0 + 5 5.5 + 6.5 14 * 15 0 + 5 10 + 11 14 * 15 20 + 25 1 + 2 14 * 15 20 * 25 5 + 6 14 + 15 20 * 25 9 * 10 14 * 15
    Table 2 shows an implementation example for the measurement of the constants with a prototype of the sensor head. The following states must be set during the measurement:
    During the calibration, therefore, at least 3 different CO 2 concentrations are measured at at least 2 different temperatures and in each case at least 3 different sugar concentrations (and thus refractive indices n). This results in the 12 model parameters for the chosen analytical approach.
    This evaluation of the calibration measurements made for the known CO 2 concentrations gives the following constants:
    Ayo = -0.01983, Bnyo = -6.4902, Cny0 = -28.04101, Bryo = -0.00245 Aa1 = 0.09595, = 4.72755, C "ai = 20.50155, BTA1 = 0.00224
    Am = 14.83044, Bn, i = 26.58616, Cnt1 = 679.05946, BTli = -0.30869
    The actual calculation of the concentration then takes place from the difference values ADn and ADCo2 and the temperature T; using the given model parameters, the CO 2 values measured with the embodiment according to the invention are in excellent agreement with comparative measurements.
    In all model functions, the dependence on temperature can be neglected by setting a predetermined temperature, which the respective liquid typically has when measuring the absorption values. In such a case, the determination of the model parameters can also take place when liquids of a single temperature, which preferably corresponds to the predetermined temperature, are used. These liquids need only differ in the C02 content and in the extract content CExtrakt.
    权利要求:
    Claims (13)
    [1]
    26 * · · # * * 26 * · # # *

    1. A method for the determination of the CO 2 content (cCo 2) in a liquid to be tested, in particular in a beverage, wherein the measurement of the absorption of the liquid to be measured in at least a wavelength (A ") is measured within a first wavelength range between 4200 and 4300 nm and a first absorption value (Aco 2) is measured by the attenuated total reflection (ATR) method, wherein the measurement of the absorption of the liquid to be measured is at least one second wavelength (λ, *) is carried out within a second wavelength range between 3950 and 4050 nm and a second absorption value {A, ef) is measured by means of the attenuated total reflection (ATR) method, characterized in that - the measurement of the absorption of the measuring liquid additionally at at least a third wavelength (λη) within a third wavelength b a third absorption value (An) is measured by means of the attenuated total reflection (ATR) method, - a given model function (M) for determining the CO 2 content (ccoz) is determined on the basis of the first, and that the model function (M) is applied to the determined first, second and third absorption value (AcO 2, A, efl A ") and the result of the evaluation as CO 2 content (cCO 2) of the test to be tested Liquid is kept available.
    [2]
    2. The method according to claim 1, characterized in that - the measurement of the first absorption value (Aco2) is performed by determining the absorbed intensity in a first measuring range determined by a first wavelength range lying in the first focal wavelength (ASjCo2) and a first range width 2MC02 is, wherein the first measuring range in the range of Äs, co2 ± AAC02, and / or - that the measurement of the second absorption value (A ^) is made by determining the absorbed intensity in a second measuring range, by a lying in the second wavelength range second Focus wavelength (As, fef) and a second range width 2AArcf, wherein the second measurement range is in the range of As, ref ± AAref, and / or - that the measurement of the third absorbance value (A ") is determined by determining the absorbed intensity in a third Measuring range is made by a lie in the third wavelength range third third centroid wavelength (As, n) and a third range width 2Δλη is set, wherein the third measuring range in the range of As, n ± Δλη, wherein the first and / or second and / or third region width (2AACo2, 2AAref, 2Δλ ") is in each case in a range between 20 nm and 200 nm, in particular at 100 nm.
    [3]
    3. The method according to claim 1, characterized in that - the first absorption value (Aco2). Preferably exclusively, at a predetermined in the first wavelength range lying first wavelength (λακ) · of preferably 4260 nm, is determined, and / or - that the second absorption value (A, ef), preferably exclusively, at a predetermined lying in the second wavelength range second wavelength (λ "*), preferably 4020 nm, is determined, and / or - that the third absorption value (An), preferably exclusively, at a predetermined lying in the third wavelength range third wavelength (A"), preferably 3800 nm, is determined ,
    [4]
    4. The method according to any one of the preceding claims, characterized in that in addition to the determination of the first, second and third absorption value (Aco2> Aref, An) and the temperature (T) of the liquid to be tested is determined, - that the model function (M) for determining the CO 2 content (cCo 2) in addition to the first, second and third absorption value (Aco 2, AJ also takes into account the temperature (T) of the liquid to be tested, and - that the model function (M) on the determined first, second and third absorption value (Aco2. Λ, *, A ") and the determined temperature (T) is applied and the result of the evaluation as C02 content (CC02) of the liquid to be tested is available.
    [5]
    5. The method according to any one of the preceding claims, characterized in that before the determination of the CO 2 content (CC02) a model function (M) is created and for the determination of the CO 2 content (cco2) is available by - a variety of Reference measurements of the first, second and third absorption values for (Aco2, Aref, An) respectively different reference liquids with known CO2 content (cC02) with different, optionally known refractive index, are carried out, - the model function (M) of the mold by means of a fitting method M = M (AcO 2> Afefr An ..... B- |, ..., Bfj) 28. is created, wherein previously unknown model parameters (Bi, .... BN) to the respective predetermined C02 content (ccoj) and the determined first, second and third absorption values (Aco2, A ^ f, A ") are adjusted so that one obtained by applying the model function (M) on the first, second and third absorption values (Aco2t Afef, respectively, at least approximately, the known C02 content (ccoi).
    [6]
    6. The method according to claim 5, characterized in that in the plurality of reference measurements in each case in addition to the first, second and third absorption value (Aco2, Aref, An) and the temperature (T) of the respective reference liquid is determined - by means of a fitting method the model function (M) of the form M = M (Ac02, Aref, An, T, Cf ..... Cn) is created, whereby previously unknown model parameters (Ci, .... CN) at the respectively given C02 content (cCo2), the determined first, second and third absorption values (Aco2, A ^ f, A ") as well as the respective temperature (T) are adjusted, so that when applying the model function (M) to the first, second and third absorption values ( Aco2> A ^ f, A ") and the temperature (T) in each case, at least approximately, the known C02 content (cC02) receives.
    [7]
    7. A device for determining the content of C02 (cccw) in a liquid to be tested, comprising - a first ATR measuring unit (1) for determining a first absorption value (Aco2) at at least a first wavelength (ACo2) within a first wavelength range between 4200 and 4300 nm, - a second ATR measuring unit (2) for determining a second absorption value (Aref) at at least one second wavelength (Aref) within a second wavelength range between 3950 and 4050 nm, characterized by - a third ATR measuring unit (3) for determining a third absorption value (A ") at an at least third wavelength within a third wavelength range (A") between 3300 and 3900 nm, and - an evaluation unit (4) which is connected downstream of the ATR measuring units (1, 2, 3) and to which the results of the ATR measuring units (1, 2, 3) are fed, wherein the evaluation unit (4) has a model function (M) on the first, second and third para application value (Aco2, Aref, An) and the result of the evaluation at its output as C02 content (Ccck) of the liquid to be tested available. 29 ft. Ft. Ft. Ft. Ft. ·· ftftft
    [8]
    8. The device according to claim 7, characterized in that the ATR measuring units (1, 2, 3) for the determination of the absorbed intensity in a first, second and third measuring range are sensitive, - wherein the first measuring range by lying in the first wavelength range first center wavelength (As, co2) and a first region width 2AAC02, and the first measurement region is set in the range of As, co2 ± AAC02, and / or wherein the second measurement region is defined by a second center wavelength in the second wavelength range (As, ref ) and the second measuring range is set in the range of Asiref i AAref, and / or - wherein the third measuring range is defined by a third centroid wavelength (As, n) lying in the third wavelength range and a third range width 2Δλη and the third measuring range is set in the range of As &gt; n ± Δλ &min;, where first and / or second and / or third region width (2Δλ0ο2, 2ΔλΓβί, 2ΔΑη) each in a range between 20 nm and 200 nm, in particular at 100 nm.
    [9]
    9. Device according to one of claims 7 or 8, characterized by one of the evaluation unit (4) upstream temperature sensor (5) for determining the temperature (T) of the liquid to be tested, wherein the evaluation unit (4) a model function (M) on the first , second and third absorption value (Aco * Α, 0ί, A ") and to the temperature (T) determined by the temperature sensor (5) and the result of the evaluation at its output as CO content (cco2) of the liquid to be tested holds.
    [10]
    10. Device according to one of claims 7 to 9, characterized by a container {6} for storage or passage of the liquid to be tested, wherein the sensitive surface parts of the ATR measuring units (1, 2, 3) and optionally also the temperature sensor (5) when filling or flowing through the container (6) come into contact with the liquid to be tested with this and in particular in the interior of the vessel (6) are arranged.
    [11]
    11. Device according to one of claims 7 to 10, characterized in that - in the evaluation unit (4) memory for predetermined coefficients (Bi, B2, ...) are provided, and - that the evaluation unit (4) has a computing unit, the stored coefficients (Bi, B2, ...) as well as the first, second and third absorption value (Aco2, ί, βί, An), and optionally also the determined temperature (T), are supplied and the

    Basis of the values supplied to it, the model function (M) evaluates and keeps available at the output of the evaluation unit (4).
    [12]
    12. Device according to one of claims 7 to 11, characterized in that - each ATR measuring unit (1, 2, 3) each comprise an ATR reflection element, an ATR infrared source, and an ATR infrared sensor, or - that the ATR Measuring units (1, 2, 3) have a common ATR reflection element and a common in the first, second and third wavelength range active ATR infrared source and have a common, active in the first, second and third wavelength range ATR infrared sensor, wherein in the beam path between the ATR Infrarotquefle and the ATR infrared sensor, an adjustable filter, in particular a filter wheel or a Fabry-Perot interferometer, is provided, which is depending on its setting only for radiation in the first, second or third wavelength range is permeable, or - that the ATR measuring units (1, 2, 3) a common ATR reflection element and a common active in the first, second and third wavelength range ATR-I have infrared source and are provided for the first, second and third wavelength ranges each separate, located at the end of the respective beam path ATR infrared sensors, or - that the ATR measuring units (1, 2, 3) a common ATR reflection element and a common for all Have wavelength ranges sensitive ATR infrared sensor, and for the first, second and third wavelength range each separate, ATR infrared wavelengths are provided.
    [13]
    13. Device according to one of claims 7 to 12, characterized in that the ATR measuring units (1, 2a, 2b, 3) at least two separate ATR infrared sources (12a, 12b) and associated ATR infrared sensors (13a, 13b) have , each of which has mutually independent beam paths and are different sensitively for every two measuring ranges, wherein in each case one measuring unit (2a) of the first infrared sensor (13a) and one measuring unit (2b) of the second infrared sensor (13b) are respectively sensitive to the same wavelength range and one Referencing unit is provided, which multiplies the measured value of the third measuring unit (3) with the ratio of the measured values of the two measuring units (2a, 2b) sensitive to the same wavelength range and makes them available at their output. Vienna, on February 20, 2012
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    同族专利:
    公开号 | 公开日
    US20130275052A1|2013-10-17|
    EP2629093A1|2013-08-21|
    AT512291B1|2013-07-15|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    AT2112012A|AT512291B1|2012-02-20|2012-02-20|METHOD AND DEVICE FOR DETERMINING THE CO2 LEVEL IN A LIQUID|AT2112012A| AT512291B1|2012-02-20|2012-02-20|METHOD AND DEVICE FOR DETERMINING THE CO2 LEVEL IN A LIQUID|
    EP13455002.9A| EP2629093A1|2012-02-20|2013-02-15|Method and device for determining the CO2 content of a fluid|
    US13/771,543| US20130275052A1|2012-02-20|2013-02-20|Method and device of determining a co2 content in a liquid|
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