Infrared gas analyzer and method for analyzing gas

Abstract

The invention relates to a gas analyzer module (1) for analyzing a measurement gas (7), comprising:-a light-pneumatic detection system (11) designed to detect infrared radiation (2) radiated through the measurement gas (7), the light-pneumatic detection system (11) comprising a pressure or flow-sensitive sensor (14), and the light-pneumatic detection system (11) being designed to generate a measurement signal, the measurement signal being detected by the light-pneumatic detection system (11); -a compensation system (6, 13a, 13b) designed to generate a compensation signal in order to compensate for disturbance effects, the compensation system comprising further pressure or flow-sensitive sensors,-an analysis system (20) designed to generate a measurement result as a function of a difference between the measurement signal and the compensation signal, and-a reflection system (15, 16) designed to reflect the measurement result on the basis of the difference between the measurement signal and the compensation signal. The reflector is designed to reflect back the infrared radiation (2) that has passed through the optical-pneumatic detection system (11) to the optical-pneumatic detection system (11). The module (1) is characterized in that the reflection system (15, 16) comprises:-a reflection plate (17) comprising a rough surface designed to diffuse back the infrared radiation (2) radiated onto the reflection plate (17) to the light-pneumatic detection system (11), and-one or more spacers (18a, 18b, 18c, 18d, 18e, 18f) designed to provide a specific distance (19) between the reflection plate (17) and the light-pneumatic detection system (11), to determine the amount of infrared radiation (2) diffusely reflected back to the opto-pneumatic detection system (11).

Description

Technical Field

[0001] This disclosure relates to a gas analyzer module for analyzing and measuring gases according to claim 1. Furthermore, this disclosure also relates to a method for analyzing and measuring gases according to claim 11. Background Technology

[0002] DE 10 2012 212 978 B3 discloses an infrared gas analyzer module in which modulated infrared radiation is radiated onto a photo-pneumatic detection system.

[0003] WO 2021 / 160379 A1 discloses an infrared gas analyzer that employs modulated infrared radiation.

[0004] As disclosed at https: / / mall.industry.siemens.com / mall / de / WW / Catalog / Products / 10140311#Technische%20Daten, the Siemens Ultramat 7 is a gas analyzer module that uses modulated infrared radiation to analyze the measurement gas. The relevant physical principle is referred to in scientific literature as NDIR (Non-Dispersive Infrared spectroscopy). The Ultramat 7 discloses a decoupler that reflects a portion of the infrared radiation radiated through the measurement gas back to the measurement gas to reduce cross-interference effects from other gases. The decoupler includes a conical mirror that reflects the infrared radiation in a directional manner. The Ultramat 7's decoupler is quite sensitive to mechanical tolerances, resulting in a higher risk of quality problems. Furthermore, due to the use of moving parts in the Ultramat 7's decoupler, time stability issues may also arise.

[0005] WO 2009 / 153099 A1 discloses a microflow sensor for measuring the flow rate of a flowing medium.

[0006] EP 0 022 246 A1 discloses a non-dispersive IR gas analyzer conforming to the principle of dual-beam chopper light, which has a radiation source, a measuring cell, a reference cell, a rotating aperture, a gas-filled detector chamber, and a device for converting the pressure difference between its volumes into an electrical signal. Summary of the Invention

[0007] The purpose of this invention is to improve the rigidity, stability, and measurement accuracy of a gas analyzer module.

[0008] This problem is solved by a gas analyzer module for analyzing and measuring gases, which includes: - An optical-pneumatic detection system designed to detect infrared radiation passing through a measurement gas, wherein the optical-pneumatic detection system includes a pressure or flow-sensitive sensor, and wherein the optical-pneumatic detection system is designed to generate a measurement signal. - A compensation system, designed to generate a compensation signal to compensate for interference effects, includes other pressure or flow-sensitive sensors. - The analysis system is designed to generate measurement results based on the difference between the measured signal and the compensation signal, and - The reflection system is designed to reflect infrared radiation that has passed through the photo-pneumatic detection system back to the photo-pneumatic detection system.

[0009] The module is characterized in that the reflection system includes: - A reflector, including a roughened surface designed to diffusely reflect infrared radiation radiated onto the reflector back to the photo-pneumatic detection system, and - One or more spacers are designed to provide a specific distance between the reflector and the photo-pneumatic detection system to determine the amount of infrared radiation diffusely reflected back to the photo-pneumatic detection system.

[0010] Typically, infrared radiation is reflected back to the photo-pneumatic detection system to compensate for gas cross-interference within the system. One or more spacers, combined with a reflector, provide an adjustable amount of diffusely reflected infrared radiation back to the photo-pneumatic detection system. As the distance between the reflector and the system increases, the amount of infrared radiation reflected back decreases, and vice versa.

[0011] The number of different components used in the gas analyzer module of the present invention (each used in the decoupler of the present invention) is relatively small. Furthermore, the complexity of the components used is low, thereby reducing the risk of quality problems. In addition, there are no moving mechanical parts, thus giving the gas analyzer module of the present invention high robustness.

[0012] One or more spacers may include an absorbing surface designed to absorb a portion of the infrared radiation diffusely reflected back to the photo-pneumatic detection system.

[0013] As an alternative, one or more spacers can be transparent to infrared radiation, allowing a portion of the infrared radiation diffusely reflected back to the photo-pneumatic detection system to be transmitted through the gas analyzer. Therefore, one or more spacers must be opaque to external radiation (such as sunlight).

[0014] By employing the two optional improvements described above, a portion of the infrared radiation diffusely reflected by the reflector can be prevented from radiating into the photo-pneumatic detection system. Consequently, the amount of infrared radiation entering the photo-pneumatic detection system can be determined.

[0015] In a further improvement to the invention, the number of spacers is adjustable to limit the amount of diffusely reflected infrared radiation returned to the photo-pneumatic detection system. Thus, the spacers can be connected to each other and to the reflector and the photo-pneumatic detection system, particularly via screw connections.

[0016] By combining a specific number of spacers, the amount of infrared radiation reflected back to the photo-pneumatic detection system can be easily set. This allows the gas analyzer module to flexibly adapt to different measurement needs (such as different measurement gases or different environmental conditions).

[0017] The spacer can be made of aluminum, wherein at least the portion of the spacer that can be irradiated by diffusely reflected infrared radiation has been anodized to absorb diffusely reflected infrared radiation radiated thereon. Anodized aluminum is mechanically stable and its shape can be flexibly manufactured.

[0018] Preferably, the thickness of the spacer is in the range of 100 micrometers to 5 millimeters, more preferably in the range of 300 micrometers to 1 millimeter. The thickness is a linear extension of the spacer along the direction from the reflector toward the photo-pneumatic detection system.

[0019] The surface of the reflector irradiated by infrared radiation can be made of aluminum. Aluminum is mechanically stable and its shape can be flexibly manufactured. The grain size of aluminum can range from 50 micrometers to 500 micrometers, preferably from 150 micrometers to 350 micrometers. Therefore, the surface of the reflector irradiated by infrared radiation can be sandblasted.

[0020] The problem described above is also solved by a method for analyzing and measuring gases using a gas analyzer module as described above. Attached Figure Description

[0021] The features of the embodiments of this disclosure will become clear from the following detailed description of the accompanying drawings. For the sake of brevity, reference numerals or features having previously described functions may be described or not described in conjunction with other illustrations in which these reference numerals or features appear.

[0022] Figure 1 The general structure of the gas analyzer module is shown; Figure 2 The general structure of the reflection system of the gas analyzer module is shown; Figures 3a-c show a specific structural example of the reflection system; and Figure 4 The dependence of gas cross-interference on the height of the spacer in the reflective system is shown. Detailed Implementation

[0023] Figure 1 The gas analyzer module 1 is shown. In the gas analyzer module 1, the infrared radiation 2 generated by the infrared radiation source 3 is split into a measurement optical path passing through the measurement cell 5 and a comparison optical path passing through the reference cell 6 by means of the beam splitter 4.

[0024] The measuring gas 7, whose concentration is to be determined, flows in through inlet 8, passes through measuring cuvette 5, and flows out through outlet 9. The reference cell 6 is filled with a reference gas, such as nitrogen.

[0025] With the aid of a modulation device 10 positioned between the beam splitter 4 and the cuvettes 5 and 6, such as a rotating aperture wheel or impeller, radiation 3 is alternately released and blocked at the measuring cell 5 and the reference cell 6, thus causing the two cells 5 and 6 to be alternately irradiated and blocked. Infrared radiation 2 alternately emitted from the measuring cuvette 5 and the reference cuvette 6 is radiated into a photo-pneumatic detection system 11, which consists of two radiation-permeable chambers 12a and 12b filled with the measuring gas 7 to be measured. Chambers 12a and 12b are connected to a pressure-sensitive or flow-sensitive sensor 14, such as a micro-flow sensor. The measurement signal, based on the difference in absorption between the measuring cuvette 5 and the reference cuvette 6, has a modulation frequency f. Furthermore, the measurement signal includes an interference signal component, which is the sum of the absorptions in the cuvettes 5 and 6, and has a frequency twice the modulation frequency 2f.

[0026] The photo-pneumatic detection system 11 includes two additional gas chambers 13a and 13b, which are filled with the same measuring gas as chambers 12a and 12b.

[0027] The measurement signal and the compensation signal are processed in the analysis system 20 to obtain the measurement result with the aid of the compensation signal, which is the concentration of the gas of interest, wherein the interference of external influences on the measurement result is reduced.

[0028] To reduce or avoid cross-interference of gases, the infrared radiation 2 radiated through chambers 12a, 12b, 13a, and 13b is reflected back by reflection systems 15 and 16, respectively. The structure of these reflection systems 15 and 16 is described below.

[0029] Figure 2 It shows Figure 1The gas analyzer module 1 shown has a reflective system 15 on its left side. A reflective system 16 has a similar structure. The reflective system 15 includes a reflector 17 and six spacers 18a, 18b, 18c, 18d, 18e, and 18f. The reflector 17 includes a rough surface designed to diffusely reflect infrared radiation 2 radiated onto the reflector 17 back to the photo-pneumatic detection system 11.

[0030] The surface of the reflector 17, which is irradiated by infrared radiation 2, is made of aluminum. The grain size of this aluminum is in the range of 50 micrometers to 500 micrometers, and the surface of the reflector 17 irradiated by infrared radiation 2 has been sandblasted. As a result, the infrared radiation 2 irradiated onto the surface of the reflector 17 is diffusely reflected. A possible specific structure of the reflector 17 is shown in Figure 3a.

[0031] Spacers 18a, 18b, 18c, 18d, 18e, and 18f are also made of aluminum. Each spacer includes an absorbing surface designed to absorb a portion of the diffusely reflected infrared radiation 2 back to the photo-pneumatic detection system 11. One possible specific structure for spacers 18a, 18b, 18c, 18d, 18e, and 18f is shown in Figure 3b. In this case, spacers 18a, 18b, 18c, 18d, 18e, and 18f are made of an absorbent material (PLA plastic) for infrared radiation.

[0032] The number of spacers 18a, 18b, 18c, 18d, 18e, and 18f is adjustable to limit the amount of infrared radiation 2 diffusely reflected back to the photo-pneumatic detection system 11. To achieve this functionality, the spacers 18a, 18b, 18c, 18d, 18e, and 18f, the reflector 3a, and the photo-pneumatic detection system 11 can be connected to each other by screws.

[0033] The closer the reflector 17 is to the photo-pneumatic detection system 11, the greater the amount of infrared radiation 2 reflected back to the photo-pneumatic detection system 11. Consequently, the smaller the portion of reflected infrared radiation 2 absorbed by the spacers 18a, 18b, 18c, 18d, 18e, and 18f, the greater the total thickness 19 of the spacers 18a, 18b, 18c, 18d, 18e, and 18f.

[0034] Figure 4 The dependence of gas cross-interference on the total thickness 19 of spacers 18a, 18b, 18c, 18d, 18e, and 18f is shown. The X-axis represents the total thickness 19 of spacers 18a, 18b, 18c, 18d, 18e, and 18f (in mm), and the Y-axis represents the gas cross-interference value (ranging from -7.000 to 8.000 in any unit).

[0035] Figure 4An optimal total thickness of approximately 4.5 mm is shown. This dependence depends on the gas being analyzed. Tests indicate that a thickness of 300 micrometers to 1 millimeter is sufficient for spacers 18a, 18b, 18c, 18d, 18e, and 18f.

[0036] The gas analyzer module 1 of the present invention, featuring the newly proposed reflection system 15, significantly reduces gas cross-interference. Furthermore, the proposed reflection system 15 has a rigid structure and allows only minimal mechanical tolerances that could lead to optical instability. Overall, the gas analyzer module 1 described above is significantly more efficient than the gas analyzer module 1 described in the prior art.

[0037] Although several embodiments have been described in detail, it should be understood that the disclosed embodiments can be modified. Therefore, the above description should be considered non-limiting.

Claims

1. A gas analyzer module (1) for analyzing and measuring gas (7), comprising: - An optical-pneumatic detection system (11) is designed to detect infrared radiation (2) passing through the measuring gas (7), wherein the optical-pneumatic detection system (2) includes a pressure or flow-sensitive sensor (14), and wherein the optical-pneumatic detection system (11) is designed to generate a measurement signal. - Compensation systems (11, 12b, 13b) are designed to generate compensation signals to compensate for interference effects; these systems include other pressure or flow-sensitive sensors. - The analysis system (20) is designed to generate measurement results based on the difference between the measured signal and the compensation signal, and - The reflection system (15, 16) is designed to reflect the infrared radiation (2) that has passed through the photo-aerodynamic detection system (11) back to the photo-aerodynamic detection system (11). Its features are, The reflection system (15, 16) includes: - A reflector (17) includes a rough surface designed to diffusely reflect the infrared radiation (2) radiated onto the reflector (17) back to the photo-aerodynamic detection system (11), and One or more spacers (18a, 18b, 18c, 18d, 18e, 18f) are designed to provide a specific distance (19) between the reflector (17) and the photo-pneumatic detection system (11) to determine the amount of infrared radiation (2) diffusely reflected back to the photo-pneumatic detection system (11).

2. The gas analyzer module (1) according to claim 1, wherein, The one or more spacers (18a, 18b, 18c, 18d, 18e, 18f) include an absorbing surface designed to absorb a portion of the infrared radiation (2) diffusely reflected back to the photo-pneumatic detection system (11).

3. The gas analyzer module (1) according to claim 1, wherein, The one or more spacers (18a, 18b, 18c, 18d, 18e, 18f) are transparent to the infrared radiation (2) diffusely reflected back to the photo-aerodynamic detection system (11).

4. The gas analyzer module (1) according to any one of the preceding claims, wherein, The number of the spacers (18a, 18b, 18c, 18d, 18e, 18f) is adjustable to limit the amount of infrared radiation (2) diffusely reflected back to the optical-pneumatic detection system (11).

5. The gas analyzer module (1) according to claim 4, wherein, The spacers (18a, 18b, 18c, 18d, 18e, 18f) can be connected to each other and to the reflector (17) and the photo-pneumatic detection system (11), particularly via screw connections.

6. The gas analyzer module (1) according to any one of the preceding claims, wherein, The spacers (18a, 18b, 18c, 18d, 18e, 18f) are made of aluminum, wherein at least the portion of the spacers (18a, 18b, 18c, 18d, 18e, 18f) that is radiated by diffuse infrared radiation (2) has been anodized to absorb diffuse infrared radiation (2) radiated onto the spacers.

7. The gas analyzer module (1) according to any one of the preceding claims, wherein, The thickness of the spacers (18a, 18b, 18c, 18d, 18e, 18f) is in the range of 100 micrometers to 5 millimeters, preferably in the range of 300 micrometers to 1 millimeter.

8. The gas analyzer module (1) according to any one of the preceding claims, wherein, The surface of the reflector (17) irradiated by the infrared radiation (2) is made of aluminum.

9. The gas analyzer module (1) according to claim 8, wherein, The grain size of the aluminum is in the range of 50 micrometers to 500 micrometers, preferably in the range of 150 micrometers to 350 micrometers.

10. The gas analyzer module (1) according to claim 8 or 9, wherein, The surface of the reflector (17) irradiated by the infrared radiation (2) has been sandblasted.

11. A method for analyzing and measuring gases using a gas analyzer module (1) according to any one of the preceding claims.

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