Method for operating optical gas measurement system, optical gas measurement system and computer program product

Abstract

A method of operating an optical gas measurement system, an optical gas measurement system and a computer program product. The invention relates to a method for operating an optical gas measuring system for determining the concentration of a measurement gas having a line spectrum, to a corresponding optical gas measuring system and to a corresponding computer program product. With the subject matter of the present invention, an estimated ambient pressure can be determined.

Description

Technical Field

[0001] The invention relates to a method for operating an optical gas measuring system for concentration determination of a measurement gas having a line spectrum, a corresponding optical gas measuring system and a corresponding computer program product. Background Art

[0002] Optical gas measuring systems and methods for operating optical gas measuring systems are known. An optical gas measuring system has a sample space which can be filled with a measuring gas to be measured (also called target gas) or with a sample gas comprising a measuring gas. Certain properties of the measuring gas or the sample gas, in particular its absorption properties, can be measured by a suitable detector, whereby it is possible to determine the concentration of the measuring gas in the sample space.

[0003] Such optical gas measuring systems (hereinafter also referred to simply as gas measuring systems) are known, for example, from DE 197 13 928 C1, DE 196 11 290 A1 and EP 3 504 535 B 1.

[0004] The concentration determination is usually based on the signals generated by at least one measuring detector and at least one reference detector. A quotient is usually formed from the signals of these detectors in order to compensate for errors acting on both detectors simultaneously. However, some influences acting on both detectors simultaneously cannot be compensated in this way.

[0005] It is thus known that, according to the ideal gas law, the density of the measurement gas or sample gas in the sample space is influenced by the ambient pressure. At low ambient pressures, the density is low, i.e. fewer gas molecules are located in the sample space, so that there are also fewer molecules of the measurement gas, even if the concentration of the measurement gas in the sample space does not change. However, due to the reduced number of gas molecules in the sample space, the absorption properties of the gas in the sample space change, so that the correspondingly calculated concentration of the measurement gas erroneously results in a lower concentration than the actual concentration. At high ambient pressures, the density of the measurement gas or sample gas is higher, and the correspondingly calculated concentration of the measurement gas erroneously results in a higher concentration than it actually is. In the case of an increase in the ambient pressure from, for example, 1000 mbar to, for example, 1200 mbar, the concentration calculated without compensation for pressure influences (pressure compensation) is, for example, 20% higher than the actual concentration.

[0006] In order to at least partially compensate for distortions of the calculated concentration of the measurement gas, it is therefore known to provide a pressure sensor which generates a corresponding pressure signal and to use the pressure signal to correct the calculated concentration of the measurement gas, for example taking into account the Lambert-Beer law.

[0007] A gas measuring device with pressure compensation is known, for example, from EP 3 370 057 A1.

[0008] However, this known solution requires the provision of a pressure sensor, which increases the costs for the production of the gas measuring device. In the case of corrosive measuring gases, the problem also arises that corrosion and thus failures of the pressure sensor may occur. Selecting a corrosion-resistant pressure sensor further increases the costs of the gas measuring device. Summary of the invention

[0009] The object of the present invention is therefore to provide a method for operating an optical gas measuring system for concentration determination of a measurement gas having a line spectrum, a corresponding optical gas measuring system and a corresponding computer program product which enable an estimation of the ambient pressure without having to provide a pressure sensor.

[0010] This object and other objects are achieved by the subject matter of the independent claims and by the dependent claims.

[0011] The dependent claims, the description and the drawings provide further features and advantageous embodiments of the invention.

[0012] According to the present invention, a method is provided for operating an optical gas measuring system for concentration determination of a measurement gas by absorption of radiation, wherein the measurement gas has a line spectrum.

[0013] The method has the following steps: a) receiving a first measurement signal, which indicates a first radiation intensity at a first measuring wavelength or at a first measuring wavelength range, b) receiving a second measurement signal, which indicates a second radiation intensity at a second measuring wavelength or at a second measuring wavelength range, wherein the first measuring wavelength or the first measuring wavelength range is different from the second measuring wavelength or the second measuring wavelength range, c) calculating a determination value, which indicates a quotient of the received first measurement signal and the received second measurement signal, d) receiving comparison information, which indicates a plurality of possible quotients of the first measurement signal and the second measurement signal for corresponding plurality of possible ambient pressures, e) comparing the determination value with the comparison information in order to determine a quotient of the plurality of possible quotients that has the highest consistency with the determination value, f) determining to which of the possible ambient pressures a quotient of the plurality of possible quotients corresponds in order to obtain an estimated ambient pressure, and g) providing the estimated ambient pressure.

[0014] In the context of the present invention it has been recognized that the so-called effect of pressure broadening of a measurement gas having a line spectrum can be used to determine and provide information about the ambient pressure acting on the measurement gas.

[0015] Measuring gases with line spectra are, for example, methane and carbon dioxide. When the pressure changes, in the case of measuring gases with line spectra, in addition to the effect of the density change described at the beginning, there is also a change in the line spectrum, that is, it becomes wider when the pressure increases and narrower when the pressure decreases and increases. This effect is collectively referred to as pressure broadening. The idea on which the present invention is based is to use the pressure-related changes of the line spectrum in order to infer the ambient pressure. This is achieved by receiving corresponding measurement signals of two different measurement wavelengths or measurement wavelength ranges, that is, obtaining information at two different points of the spectrum. The two measurement signals are correlated with each other and thus constitute a characteristic value, namely a quotient, which is therefore related to the currently existing ambient pressure. By comparing the quotient with the corresponding predetermined comparison information, it can then be determined which of the possible ambient pressures the quotient corresponds to, and thus the estimated ambient pressure can be determined and provided.

[0016] In the simplest embodiment of the invention, only the estimated ambient pressure is provided and can be used in various ways. For example, it is possible to output the estimated ambient pressure to a user of the gas measuring system for information purposes. It is also possible that, when a pressure sensor is provided for determining the ambient pressure, the estimated ambient pressure can be determined in a redundant manner for the determination of the ambient pressure, whereby the error tolerance of the determination of the ambient pressure can be improved. It is also possible to use the information about the estimated ambient pressure for at least partial pressure compensation. Other uses of the estimated ambient pressure are possible.

[0017] In the context of the present invention, a measuring gas is understood to be a gas or a gas mixture whose concentration in the gas or gas mixture to be examined (sample gas) can be determined by means of absorption spectroscopy and which furthermore has a line spectrum.

[0018] A measurement signal is understood to be a signal which indicates the radiation intensity at a measurement wavelength or at a measurement wavelength range. The measurement signal can be obtained by a radiation detector.

[0019] Measuring wavelength ranges that differ from one another are understood to be measuring wavelength ranges that differ from one another at least in one wavelength. For example, the measuring wavelength ranges differ from one another if their center wavelengths differ.

[0020] The determined value is understood to be a value indicating the quotient of the first received measurement signal and the second received measurement signal. In one example, the determined value is derived by directly forming the quotient of the first received measurement signal and the second received measurement signal. In another example, the determined value is derived by forming the quotient of concentration signals of two gas measuring devices that are not structurally identical, wherein the respective concentration signal indicates the quotient of the measurement signal and a reference signal.

[0021] The comparison information is understood to be information indicating a plurality of possible quotients of the first measurement signal and the second measurement signal for a corresponding plurality of possible ambient pressures. The comparison information may exist in a substantially arbitrary manner and may be provided, for example, as a lookup table. In yet another example, the comparison information may be obtainable by executing a predetermined calculation rule. The comparison information may be related to other parameters.

[0022] Preferably, step c) is performed at a first determined time point in order to obtain a first determined value, and step c) is performed (again) at a later second determined time point in order to obtain a second determined value, wherein the method additionally comprises the step: d1) determining the difference between the second determined value and the first determined value, and wherein if the difference between the second determined value and the first determined value exceeds a predetermined threshold value, step e) of the method is performed.

[0023] In this way, the robustness of the method can be increased by the fact that the estimated ambient pressure is only determined if there is a change in the determined value which exceeds a predetermined threshold value.

[0024] Preferably, step c) is repeatedly performed continuously so that the first determined value and the second determined value are obtained continuously.

[0025] Preferably, the method further comprises the step of: b1) receiving a reference signal indicating a third radiation intensity at a reference wavelength or at a reference wavelength range, wherein the reference wavelength is different from the first measuring wavelength and / or the second measuring wavelength, or wherein the reference wavelength range is different from the first measuring wavelength range and / or the second measuring wavelength range.

[0026] By shifting the reference wavelength or the reference wavelength range into a range that is different from at least one measuring wavelength or at least one measuring wavelength range, preferably different from two measuring wavelengths or two measuring wavelength ranges, the influence of pressure broadening on the measured gas concentration in the range of lower measured gas concentration can be advantageously reduced.

[0027] Preferably, the method further comprises the following steps: b2) determining the concentration of the measurement gas from the first measurement signal and / or from the second measurement signal and from the reference signal, h) at least partially correcting the determined concentration based on the estimated ambient pressure in order to obtain a corrected concentration of the measurement gas, and i) providing the corrected concentration of the measurement gas.

[0028] In this way, the determined concentration of the measurement gas can be at least partially corrected by taking into account the estimated ambient pressure.

[0029] The concentration of the measurement gas can be determined in a known manner from the one or more measurement signals and the reference signal.

[0030] The measurement gas preferably comprises methane and / or carbon dioxide.

[0031] In this way, it is possible to implement the invention in known gas measuring devices by merely adding a further suitable measurement signal to the two measurement signals or reference signals which are usually already present.

[0032] In the case of carbon dioxide, there is also the advantage that carbon dioxide is present in almost every environment on Earth, so that in this case a gas measuring device can be provided to provide an estimated ambient pressure, wherein every other radiation detector is free to measure other gases. This is better with methane, but methane is not present in almost every environment.

[0033] According to the invention, an optical gas measuring system is furthermore provided for determining the concentration of a measurement gas having a line spectrum by means of radiation absorption.

[0034] The optical gas measuring system comprises: a first radiation detector, which is set up to indicate a first radiation intensity at a first measuring wavelength or at a first measuring wavelength range; a second radiation detector, which is set up to indicate a second radiation intensity at a second measuring wavelength or at a second measuring wavelength range; and an evaluation unit, which is set up to perform some or all steps of the above-mentioned method.

[0035] A radiation detector is understood to be a device that is designed to measure electromagnetic radiation, i.e. light. A radiation detector can be designed, for example, as a photoresistor, a photodiode, a phototransistor, a bolometer, a pyroelectric detector, a pyroelectric detector and / or a thermal detector. Other examples of suitable designs of radiation detectors are detector arrays, line detectors, CCD sensors and CMOS sensors.

[0036] Each embodiment of the radiation detector may have one or more optical filters. Each embodiment of the radiation detector may additionally or alternatively have one or more digital filters. With the aid of optical filters and / or digital filters (hereinafter also referred to as filters in a general sense), the corresponding radiation detector can be set up to indicate the corresponding radiation intensity.

[0037] An optical filter is understood to be a component of a gas measuring system which selects the incident radiation according to a predetermined criterion. Such a filter can be designed, for example, as a bandpass filter or a double bandpass filter and selects the radiation according to one wavelength or according to one or more wavelength ranges. An optical filter can be designed, for example, as an optical filter or a tunable filter.

[0038] Each radiation detector, i.e. the first radiation detector and / or the second radiation detector and / or each other radiation detector, can be designed as an independent component or as part of a multiple detector, for example as part of a double detector or as part of a quadruple detector. The radiation detectors can be designed to be of the same or different types.

[0039] It is possible that the plurality of radiation detectors are neither independent nor part of a multi-detector, but are provided by a common radiation detector, which provides a corresponding number of signals by switching between a plurality of filters and thereby provides a plurality of radiation detectors in the sense of the invention simultaneously. For example, the common radiation detector can provide a first measurement signal and a second measurement signal by switching between a first filter and a second filter. The same applies to each other measurement signal and reference signal, which can likewise be provided by one radiation detector or another common radiation detector by means of suitable filters.

[0040] Each of the first, second and further filters may exist as a physical component and may be arranged in the optical path upstream of the common radiation detector and / or upstream of the further common radiation detectors, or may be designed as a digital filter.

[0041] In a non-limiting example, the first radiation detector and the second radiation detector may be designed as devices of a common component, such as a component of a double detector or a quadruple detector.In addition to the first radiation detector and the second radiation detector, there may also be other radiation detectors, such as a third and a fourth radiation detector.

[0042] If the method comprises step b1), it is preferred that the gas measuring system has a third radiation detector which is designed to indicate a third radiation intensity at a reference wavelength or at a reference wavelength range.

[0043] Generally speaking, it is preferred that the gas measurement system further comprises a fourth radiation detector which is configured to indicate a fourth radiation intensity at a further reference wavelength or at a further reference wavelength range. The reference wavelength and the further reference wavelength or the reference wavelength range and the further reference wavelength range may be identical or different from one another.

[0044] Preferably, the first and third radiation detectors are provided in the first gas measuring device and the second and fourth radiation detectors are provided in the second gas measuring device.This may be done by providing one or more radiation detectors and / or by providing one or more common radiation detectors.

[0045] The gas measuring system according to the invention may have further elements, such as a sample space for accommodating a sample gas, one or more devices for influencing the propagation of radiation (mirrors, reflectors, lenses, etc.), one or more radiation sources, a control unit which may be set up to form an evaluation unit and / or one or more energy accumulators for providing energy for operating the gas measuring system.

[0046] One or more radiation sources can be set up to emit light including ultraviolet radiation and / or infrared radiation. Ultraviolet radiation is understood in this context as electromagnetic radiation with a wavelength of 10 nm to 400 nm, preferably 100 nm to 380 nm. Infrared radiation is understood in this context as electromagnetic radiation with a wavelength of 0.750 μm to 1000 μm. The one or more radiation sources can emit light in a broadband manner and / or in a narrowband manner. For example, the one or more radiation sources can be designed as one or more LEDs and / or one or more incandescent lamps.

[0047] The evaluation unit can be designed as a hardware and / or software component for carrying out the method according to the invention and preferably also for controlling the components of the gas measuring system. For example, the evaluation unit can be designed as a software module of a computer or a hardware and / or software module of a gas measuring device, which can be part of the gas measuring system and can be, for example, a processor or a microcontroller.

[0048] The energy store or stores may be designed, for example, as accumulators and / or batteries.

[0049] The gas measurement system may consist of a portable, mobile or fixed gas measurement device with an open or closed sample cell, or may be designed as a distributed system which may include one or more gas measurement devices.

[0050] The gas measurement system can be constructed in an open path configuration, wherein one system component can have one or more radiation sources and another system component can have a first and a second radiation detector. In another variant, another system component has a first radiation detector and another system component has a second radiation detector.

[0051] The optical gas measurement system preferably has a sample cell defining an absorption path, wherein the length of the absorption path is at least 10 cm, preferably at least 80 cm.

[0052] The provision of such an absorption path has proven to be particularly advantageous in view of the measuring properties of gas measuring systems.

[0053] According to the invention, a computer program product is furthermore provided, which comprises instructions which cause the aforementioned optical gas measuring system to perform some or all of the aforementioned method steps.

[0054] Every disclosure concerning the method is also considered to be disclosed in conjunction with the gas measurement system, and vice versa. Every disclosure concerning the gas measurement system is also considered to be disclosed in conjunction with the computer program, and vice versa. Every disclosure concerning the method is also considered to be disclosed in conjunction with the computer program, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] These and other features, effects and advantageous embodiments of the present invention can also be seen from the following description of the drawings.

[0056] Figure 1 An embodiment of the method according to the invention is shown,

[0057] Figure 2 Schematic diagram showing the pressure broadening effect in a pressure-concentration diagram,

[0058] Figure 3 Schematic diagram showing possible quotients of the measurement signal as a function of concentration and pressure,

[0059] Figure 4 An embodiment of a gas measurement system according to the present invention is shown, and

[0060] Figure 5 Another embodiment of a gas measuring system according to the invention is shown. DETAILED DESCRIPTION

[0061] According to the present invention, a method 100 is provided for operating an optical gas measuring system 200 for concentration determination of a measurement gas by radiation absorption, wherein the measurement gas has a line spectrum. Figure 1 An embodiment of such a method 100 is shown in FIG. Figure 1 The embodiment of the invention furthermore has optional steps indicated by dashed lines.

[0062] The method 100 comprises at least steps a), b), c), d), e), f) and g).

[0063] Step a) is receiving a first measurement signal M1 which is indicative of a first radiation intensity at a first measuring wavelength or at a first measuring wavelength range.

[0064] Step b) is receiving a second measurement signal M2 which is indicative of a second radiation intensity at a second measuring wavelength or at a second measuring wavelength range.

[0065] The first measuring wavelength or the first measuring wavelength range is different from the second measuring wavelength or the second measuring wavelength range.

[0066] Step c) is to calculate a determined value B, B1, B2 which indicates the quotient Q of the first received measurement signal M1 and the second received measurement signal M2.

[0067] Step d) is receiving comparison information I, I0, I1, I2, I3 indicating a plurality of possible quotients of the first measurement signal M1 and the second measurement signal M2 for a corresponding plurality of possible ambient pressures p0, p1.

[0068] Step e) is to compare the determined value B, B1, B2 with the comparison information I, I1, I2, I3 in order to determine the quotient I1 among the multiple possible quotients I, I0, I1, I2, I3 that has the highest consistency with the determined value B, B1, B2.

[0069] Step f) is to determine which ambient pressure p of the possible ambient pressures p0 and p1 corresponds to the quotient I1 among the multiple possible quotients I, I0, I1, I2, and I3, so as to obtain the estimated ambient pressure p _ est.

[0070] Step g) is to provide the estimated ambient pressure p _ est.

[0071] As explained at the outset, the invention is based on the idea of ​​using the pressure-dependent changes in the line spectrum to infer the ambient pressure. In the case of non-pressure-compensated gas measuring devices, the effect of pressure broadening is Figure 2 This is schematically shown in a pressure-concentration diagram in which the ambient pressure p is plotted against the concentration k of the measured gas. The gas measuring device displays the concentration K0 as the concentration at the calibration pressure p0 (applicable) when the concentration k of the measured gas increases without a pressure change. However, if there are pressures different from the calibration pressure p0, the effect of the pressure broadening causes the specific concentration K to deviate from the actually present concentration K*. However, by knowing the ambient pressure p1, at least partial compensation of the specific concentration K* is possible.

[0072] Combination Figure 3 The mode of action of steps c), d), e) and f) according to the invention is explained in more detail.

[0073] exist Figure 3In the method, the possible quotients I0, I1, I2, I3 of the measurement signals M1, M2 as a function of the concentration k are schematically plotted as a family of curves for the corresponding ambient pressures p0, p1, p2, p3, which are known by means of the comparison information. In step c) of the method, a determined value B is calculated, which indicates the quotient Q of the first measurement signal M1 received and the second measurement signal M2 received as a function of the concentration k of the measured gas, for example at the currently existing concentration K. In step e), the determined value B is compared, for example, with the family of curves of the possible quotients I0, I1, I2, I3 in order to determine the quotient I1 which has the highest consistency with the determined value B. It is known from the comparison information to which pressure p1 the quotient I1 determined in this way corresponds, so that by means of this assignment it can be determined which is the estimated ambient pressure p1. _ est.

[0074] It is also possible to determine the corresponding estimated ambient pressure p by interpolating between two curves of the curve family, in this example between I1 and I2. _ est, the ambient pressure taking into account the deviation (if any) from one of the existing curves.

[0075] In a variant not shown, the comparison information is not formed by a predetermined set of curves, but is obtained by executing a calculation criterion, for example an empirically determined function which assigns a certain value to the corresponding estimated ambient pressure.

[0076] like Figure 1 As shown in , method 100 may further optionally include: performing step c) at a first determined time point to obtain a first determined value B1, and performing step c) at a later second determined time point to obtain a second determined value B2, wherein method 100 may additionally include the step: d1) determining the difference between the second determined value B2 and the first determined value B1, wherein if the difference between the second determined value B2 and the first determined value B1 exceeds a predetermined threshold value, then performing step e) in this case.

[0077] Step c) may optionally be performed repeatedly continuously, so that the first determined value B1 and the second determined value B2 are obtained continuously.

[0078] like Figure 1 As shown in , the method 100 may further optionally include a step b1).

[0079] Step b1) is receiving a reference signal R which indicates a third radiation intensity at a reference wavelength or in a reference wavelength range, wherein the reference wavelength is different from the first measuring wavelength and / or different from the second measuring wavelength or wherein the reference wavelength range is different from the first measuring wavelength range and / or different from the second measuring wavelength range.

[0080] like Figure 1 As shown in , method 100 may further optionally include steps b2), h) and i).

[0081] Step b2) is to determine the concentration K of the measurement gas from the first measurement signal M1 and / or from the second measurement signal M2 and from the reference signal R.

[0082] Step h) is based on the estimated ambient pressure p _ est at least partially corrects the determined concentration K in order to obtain a corrected concentration K* of the measurement gas.

[0083] Step i) is to provide a corrected concentration K* of the measurement gas.

[0084] The measured gas may include methane and / or carbon dioxide.

[0085] According to the invention, a gas measuring system 200 is also provided for determining the concentration of a measurement gas having a line spectrum by means of radiation absorption. Figure 4 and Figure 5 An embodiment of a gas measurement system 200 according to the present invention is shown in FIG.

[0086] Each gas measurement system 200 according to the present invention comprises: a first radiation detector 30, which is configured to indicate a first radiation intensity at a first measuring wavelength or in a first measuring wavelength range, and a first filter 31 is preferably assigned to the first radiation detector; a second radiation detector 40, which is configured to indicate a second radiation intensity at a second measuring wavelength or in a second measuring wavelength range, and a second filter 41 is preferably assigned to the second radiation detector; and an evaluation unit 10, which is configured to perform some or all steps a), b),... of method 100.

[0087] The gas measuring system 200 may also have further components, such as a storage unit 11 which may be designed as part of the evaluation unit 10, a housing 50 for accommodating some or all components of the gas measuring system 200, a reflector 70 and a display device for providing and / or outputting information, such as an estimated ambient pressure p _ est and / or the determined concentration K and / or the corrected concentration K*.

[0088] The gas measurement system 200 may have other and / or Figure 4 and Figure 5 The different components shown in .

[0089] exist Figure 4In the embodiment of the present invention, the gas measuring system 200 is designed as a gas measuring device, which has a reflector 70 arranged outside the housing 50, which reflects radiation (schematically shown as a beam S) from the radiation source 20 and deflects the radiation toward the first radiation detector 30 and the second radiation detector 40. In this case, the radiation passes through a sample space formed by a sample cell 80 between the housing 50 and the reflector 70 and is (partially) absorbed by the measurement gas that is possibly present.

[0090] However, the gas measurement system 200 can also be designed as a distributed system, in which the radiation source 20 and the radiation detectors 30, 40 are arranged spatially separated from each other in different components of the system and aligned with each other, i.e. in an open path structure, which does not require a reflector 70. In this case, the sample cell is an open sample cell, i.e. not a structural component.

[0091] according to Figure 5 The gas measurement system 200 is designed as a variant of a distributed system, which includes two Figure 4 The gas measuring device and the data processing unit 10 constituting the evaluation unit 10. However, unlike the Figure 4 The gas measuring device of the gas measuring system 200 has a first radiation detector 30 and a third radiation detector 32, the third radiation detector indicating a third radiation intensity at a reference wavelength or in a reference wavelength range, and a second gas measuring device has a second radiation detector 40 and a fourth radiation detector 42, the fourth radiation detector indicating a fourth radiation intensity at a second reference wavelength or in a second reference wavelength range. The gas measuring devices of the gas measuring system 200 are configured to provide the concentrations K1, K2 of the measured gas calculated from the corresponding signals to an evaluation unit 10 via a corresponding data interface 60, the evaluation unit being configured according to the invention to determine an estimated ambient pressure p _ est. Therefore, according to Figure 4 Unlike the gas measuring devices of , the gas measuring devices of gas measuring system 200 do not respectively have an evaluation unit 10 , but instead respectively have a control unit 12 which is designed to control the respective gas measuring device.

[0092] Not shown is a computer program product according to the invention, which is likewise provided and comprises instructions which cause the above-described optical gas measurement system 200 to perform some or all of the above-described steps a), b), . . . of the method 100 .

[0093] Reference numerals list

[0094] 10 Evaluation Units

[0095] 11 Storage Unit

[0096] 12 Control Unit

[0097] 20 Radiation Source

[0098] 30 First Radiation Detector

[0099] 31 First filter

[0100] 32. Third radiation detector

[0101] 33 Third filter

[0102] 40 Second radiation detector

[0103] 41 Second filter

[0104] 42. Fourth radiation detector

[0105] 43 Fourth filter

[0106] 50 Shell

[0107] 60 Interface

[0108] 70 Reflector

[0109] 80 Sample pool

[0110] 100 Methods

[0111] 200 Gas measurement systems, optical gas measurement systems

[0112] a), b), ... Method steps

[0113] B Determine the value

[0114] B1 First determined value

[0115] B2 Second determination value

[0116] k, K, K0, ... measure the concentration of gas

[0117] K* Corrected concentration of the measured gas

[0118] I, I0, I1... Comparison information

[0119] M1 First measurement signal

[0120] M2 Second measurement signal

[0121] p, p0, p1 ambient pressure

[0122] p_est Estimated environmental pressure

[0123] Q Quotient

[0124] R Reference signal

[0125] S-ray.

Claims

1. A method (100) for operating an optical gas measuring system (200) for determining the concentration of a measurement gas having a line spectrum by radiation absorption, the method comprising the following steps: a) receiving a first measurement signal (M1) which is indicative of a first radiation intensity at a first measuring wavelength or at a first measuring wavelength range, b) receiving a second measurement signal (M2) which is indicative of a second radiation intensity at a second measuring wavelength or at a second measuring wavelength range, wherein the first measurement wavelength or the first measurement wavelength range is different from the second measurement wavelength or the second measurement wavelength range, c) calculating a determined value (B, B1, B2) which indicates a quotient (Q) of the first received measurement signal (M1) and the second received measurement signal (M2), d) receiving comparison information (I, I0, I1, I2, I3) indicating a plurality of possible quotients of the first measurement signal (M1) and the second measurement signal (M2) for a corresponding plurality of possible ambient pressures (p, p0, p1), e) comparing the determined value (B, B1, B2) with the comparison information (I, I1, I2, I3) in order to determine the quotient (I1) of a plurality of possible quotients (I, I0, I1, I2, I3) which has the highest consistency with the determined value (B, B1, B2), f) determining to which ambient pressure (p) of the possible ambient pressures (p0, p1) a quotient (11) of a plurality of possible quotients (I, I0, I1, I2, I3) corresponds, in order to obtain an estimated ambient pressure (p _ est), and g) Provides estimated ambient pressure (p _ est).

2. The method (100) according to claim 1, wherein step c) is performed at a first determined time point to obtain a first determined value (B1), and wherein step c) is performed at a later second determined time point in order to obtain a second determined value (B2), The method (100) further comprises the steps of: d1) determining a difference between the second determined value (B2) and the first determined value (B1), and If the difference between the second determination value (B2) and the first determination value (B1) exceeds a predetermined threshold, step e) is performed.

3. The method (100) according to claim 2, Step c) is repeatedly performed continuously, so that the first determined value (B1) and the second determined value (B2) are obtained continuously.

4. The method (100) according to any one of the preceding claims, Also included are the steps: b1) receiving a reference signal (R) which is indicative of a third radiation intensity at a reference wavelength or at a reference wavelength range, Wherein the reference wavelength is different from the first measuring wavelength and / or the second measuring wavelength, or wherein the reference wavelength range is different from the first measuring wavelength range and / or the second measuring wavelength range.

5. The method (100) according to claim 4, The following steps are also included: b2) determining the concentration (K) of the measurement gas from the first measurement signal (M1) and / or from the second measurement signal (M2) and from the reference signal (R), h) Based on the estimated environmental pressure (p _ est) at least partially correcting the determined concentration (K) in order to obtain a corrected concentration (K*) of the measurement gas, and i) Provides the corrected concentration (K*) of the measurement gas.

6. The method (100) according to any one of the preceding claims, The measured gas comprises methane and / or carbon dioxide.

7. An optical gas measurement system (200) for determining the concentration of a measurement gas having a line spectrum by radiation absorption, comprising: a first radiation detector (30) which is designed to indicate a first radiation intensity at a first measuring wavelength or at a first measuring wavelength range, a second radiation detector (40) which is designed to indicate a second radiation intensity at a second measuring wavelength or at a second measuring wavelength range, An evaluation unit (10) which is designed to carry out the steps of the method (a), b), . . . ) according to any one of claims 1 to 6.

8. The optical gas measurement system (200) according to claim 7, The optical gas measurement system (200) has a sample cell (80) defining an absorption path, The length of the absorption path is at least 10 cm, preferably at least 80 cm.

9. A computer program product comprising instructions causing an optical gas measurement system (200) according to any one of claims 7 to 8 to perform the method steps according to any one of claims 1 to 6.

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