TR2023005762U5 - OPTICAL GAS SENSOR DESIGNED WITH CONVERGENT NOZZLES - Google Patents

Abstract

This invention relates to gas concentration measurement with non-dispersive infrared. More specifically, it concerns an optical gas sensor designed with converging nozzles that detects gas concentration by monitoring the absorption of radiation emitted by a source emitting electromagnetic radiation in the infrared spectrum by a gas sample as it travels through a chamber containing a gas sample.

Description

DESCRIPTION OPTICAL GAS SENSOR DESIGNED WITH CONVERGENT NOZZLES TECHNICAL FIELD This invention relates to gas concentration measurement by non-dispersive infrared. More specifically, it concerns an optical gas sensor designed with converging nozzles that detects gas concentration by monitoring the absorption of radiation emitted by a source emitting electromagnetic radiation in the infrared spectrum by a gas sample as it travels through a chamber containing a gas sample. BACKGROUND ART Today, there are many optical gas sensors designed to detect a particular gas and measure the gas concentration by using infrared radiation. These gas sensors are divided into two according to their purpose: dispersive infrared (DlR) gas detection and non-dispersive infrared (NDlR) gas detection. The aim of dispersive infrared gas detection systems is to determine the identity of a gas. Radiation emitted from a source with an infrared spectrum is first passed through the gas sample and this radiation is distributed into the spectrum with the help of a prism or filter. It then reaches a sensor. This method is generally used in gas spectrometers. In non-dispersive infrared (NDlR) gas detection systems, the purpose is to measure the concentration of a gas whose identity is known. This system generally consists of an infrared radiation source, an infrared sensor, and a gas sample chamber. NDlR gas sensors detect the attenuation of radiation based on the principle that the target gas absorbs infrared (IR) radiation. The degree of attenuation is a function of the absorption coefficient of the target gas, the optical path length of the IR radiation between the optical source and the detector, the concentration of the target gas present along that optical path, and the wavelength of the electromagnetic radiation. The relationship between these parameters is explained by the 8eer-Lambert law. The gas sample chamber is the part where the gas sample is located, and it is also called the optical path since it is the part where the rays scattered from the IR radiation source travel. When the optical path length is increased, the length at which the rays scattered from the IR radiation source can interact with the gas before reaching the detector can be increased. Thus, the sensitivity of the measurement increases. To increase sensitivity, some designs to create a long optical path are designed as a tube in US sensors. The infrared radiation source and infrared sensors are placed at the ends of the tube. However, one of the disadvantages of these sensors is that they are quite large and take up a lot of space. In order to reduce sensor sizes, optical chambers with different designs embedded in a cylindrical capsule were developed in subsequent studies. Some technical solutions to make the sensor more compact and reduce its size: The rays scattered from the US infrared radiation source are directed onto the sensor with the help of mirrors. In these designs, linearly emitting infrared radiation sources should be preferred to increase the light intensity reaching the sensor. When radiation sources that emit 360°, such as an lR incandescent lamp, are used, beam control may become difficult because lR beams traveling outside the expected path will lose more energy as a result of random reflections. In addition, mirrors used in designs to focus the rays increase the cost of the sensor. Similarly, other studies conducted to extend the optical path included optical path designs embedded in a US 9,297,758 capsule. In these patents, more complex designs were made in order to extend the optical path and direct the rays scattered from the infrared radiation source to the detector. Optical path designs designed in this way increase sensor sensitivity as they extend the optical path. The optical path designs in the cylindrical capsule in these designs may cause difficulties in production. Since the complex design and the small size of the capsule increase the need for very precise production, it also increases the production cost. In addition, the reflectivity of the surface is very important in NDlR sensor capsule designs. Therefore, after the capsule production is carried out, depending on the capsule material, polishing, coating, etc. procedures need to be implemented. Especially in designs that require coating, when the optical path is designed to be embedded in a cylindrical capsule, problems such as the coating not being equal on all surfaces and some surfaces being rough may be encountered. Another point ignored in these designs mentioned above, called the optical path or gas chamber made for the existing NDlR gas sensor, is the effects of the geometric shape, size and number of gas inlet-outlet holes on the gas flow. As the total surface area of the gas entry-exit holes increases, the amount of IR heat escaping outside the capsule also increases. However, the small total hole surface area causes the target gas to diffuse more slowly into the sensor capsule. These two situations are factors that affect the sensitivity in measurement, measurement speed and light intensity reaching the sensor. DESCRIPTION OF THE INVENTION The present invention creates a stable, compact and long optical path for NDlR gas detection. This invention provides a long optical path and a very simple structure for production. An optical path with aspherical edges and reflective surfaces was designed to direct the rays scattered from the infrared radiation source and focus them on the detector. Mirrors were not used in the invention in order not to increase the cost. However, gold plating was preferred to increase reflectivity. Parabolic reflective/focusing walls have been appropriately added to the design to direct the rays scattered from the infrared radiation source and focus them on the detector without using a mirror. Since the sensor capsule will be subjected to the coating process after production, it is designed in two parts: the optical path body and the sensor capsule cover, in order to facilitate the coating process. The fact that the optical path is not embedded in a cylindrical capsule simplifies the coating process and increases the even coating ability of the surfaces. In this way, reflectivity will be approximately equal on every surface. Another issue that affects measurement in NDlR gas sensors is gas movement. In these gas measurement systems, the gas must be filled into the capsule by diffusion and its concentration must be determined in this way. Fast diffusion is also an important point for accurate and fast concentration measurement. When the diffusion rate increases, the gas concentration in the external environment and the capsule will quickly equalize and reach equilibrium. In order for diffusion to occur, there must be gas inlet and outlet holes on the sensor capsule. In previous designs, cylindrical holes were mostly preferred. However, the size of the hole surface areas also changes the amount of photons escaping outside the capsule. As the hole surface areas are enlarged, the diffusion rate increases and photon loss also increases. This causes the light intensity reaching the sensor to decrease and, accordingly, the measurement sensitivity to decrease. In the present invention, the gas inlet and outlet holes are designed as a convergent nozzle type in order to easily increase the diffusion rate and minimize the amount of photon loss. Convergent nozzles, thanks to their geometric structure (narrowing from outside to inside), increase the diffusion rate of the gas by keeping the pressure difference between the inside of the capsule and the outside environment high. Thus, the gas concentration in the external environment and the capsule will equalize faster, and the correct concentration measurement time of the sensor will be shortened. At the same time, the amount of light escaping outside the sensor capsule can be kept to a minimum. Thus, the light intensity reaching the infrared sensor will increase. In the design, the optical path body and the sensor capsule cover have a junction point in order to fix the optical path geometry and the positions of the gas entry-exit points. The optical sensor capsule has a gas inlet-outlet hole set with proximal nozzle geometry to increase the gas diffusion rate while keeping energy loss to a minimum. With the sensor capsule subjected to gold plating in order to increase reflectivity, the rays scattered from the IR radiation source suffer less energy loss while reflecting in the optical chamber. Thus, while a long optical path is provided, the light intensity reaching the sensor is kept at a sufficient level for the sensor to take accurate and sensitive measurements. Parabolic reflecting/focusing walls were used to direct the rays scattered from the infrared radiation source and focus them on the sensor. Thus, there is no need to use mirrors in the design and a more economical design is achieved. Since the position of the sensor and infrared radiation source on the electronic card is important, there are two electronic card fixing feet on the optical path base in order to keep their positions constant and to facilitate the assembly of the electronic card and sensor capsule. In order to facilitate its adaptability to many gas measurement systems, 7 pins indicating the infrared radiation source and infrared sensor outputs are placed on the electronic card. In the invention subject to the application, gold plating was applied to the sensor capsule to obtain surfaces with high reflection rates. The same reflectivity rate can also be achieved with more economical materials or coating types. Explanation of Figures Figure 1. Schematic view of the designed optical gas sensor showing its internal details Figure 2. Top view of the optical gas sensor with its top cover removed Figure 3. Side section view Figure 4. Disassembled view of the optical gas sensor Figure 5. Perspective view of the optical gas sensor with its top cover removed Figure 6. Perspective view of the optical gas sensor with its top cover and electronic board removed Figure 7. Disassembled view of the optical gas sensor with its electronic board removed Figure 8. Mounted perspective view of the optical gas sensor Figure 9. Bottom view of the electronic board of the optical gas sensor Reference List 1 Sensor capsule cover 3 Infrared sensor 3a Infrared sensor reference channel 3b Infrared sensor measurement (active) channel 4 Peripheral path 6 Optical path body 7 Small parabolic reflecting/focusing wall 8 Large parabolic reflecting/focusing wall 9 Parabolic reflecting/focusing wall Optical path 10a Main peripheral optics path 1% Radial optical path 11 Electronic card fixing feet 12 Infrared sensor slot 13 Capsule cover fixing slot 14 Optical path body fixing protrusion Electronic card pins 16 Infrared radiation source slot 17 Infrared sensor fixing wall 18 Infrared sensor ports 19 Electronic board Inner peripheral wall 21 Electronic card fixing slot 22 Optical bus body/electronic card fixing holes 23 Infrared radiation source connection points DETAILED DESCRIPTION OF THE INVENTION In this detailed description, the preferred alternatives of the optical gas sensor designed with converging nozzles, which are the subject of the invention, are presented only for a better understanding of the subject and without any It is explained in a way that does not create a limiting effect. Thermophile sensor and IR incandescent lamp are used in the design of the invention subject to the application. Response time, sensitivity, etc. Different radiation sources and sensors can be used to further improve performance criteria. Sensor capsule cover; It surrounds the optical path and the electronic card, and with its reflective walls, allows the rays to progress in the direction of the sensor through reflections. Infrared radiation source; It emits radiation at the wavelength required for measurement in the infrared band. Infrared sensor; It produces electrical output depending on the radiation intensity falling on it. Infrared sensor reference channel; It is a sensor element that is not sensitive to the measured gas. Infrared sensor measurement (active) channel; It is a sensor element that takes measurements sensitively to the measured gas. Peripheral road; It is the environmental path along which the rays scattered from the infrared radiation source travel and contains a gas sample. Gas inlet-outlet hole set; It is a hole set designed to ensure rapid gas diffusion by utilizing the convergent nozzle geometry, while keeping the energy loss resulting from the rays escaping outside the capsule to a minimum. Optical path body; It is the inner cylindrical wall that encloses the infrared sensor and fixes its position. Small parabolic reflecting/focusing wall; A wall designed to direct the rays falling on it to the sensor or to the parabolic focuser opposite it, depending on the angle of incidence. Large parabolic reflecting/focusing wall; Parabolic focusing wall designed to focus incoming rays onto sensor channels. Parabolic reflecting/focusing wall; Parabolic wall designed to reflect the rays scattered from the radiation source to the opposite side to the main road. Optical path; It is a long optical path designed to allow the rays scattered from the radiation source to reach the sensor. Main peripheral optical path; It is the optical path part designed to ensure that the rays scattered from the radiation source reach the parabolic focuser. Radial optical path; It is the optical path part designed to ensure that the rays reaching the parabolic focuser are reflected and reach the sensor. Electronic card fixing feet; It is the pair of feet that allows the optical path and the PCB board to be combined and fixed together. Infrared sensor slot; It is an inner chamber designed to allow the sensor to be placed easily and PCB connections to be made. Capsule cover fixing slot; It is the junction point designed to ensure that the optical path and the capsule cover easily meet in the correct position, ensuring that the optical path geometry remains constant. Optical path body fixing protrusion; A protrusion designed to easily fit into the recess in the optical path in order to ensure that the two parts come together in the correct position to keep the capsule cover and optical path geometry constant. Electronic card pins; These are the connection pins used to connect the sensor to the reading circuit. Infrared radiation source housing; The slot centered on the focal point of the parabolic reflector/focus wall behind it, indicating the position of the source and allowing it to be placed in the optical capsule. Infrared sensor fixing wall; The slot that allows the sensor to be placed in the optical capsule and positioned in the correct position relative to the parabolic focuser. Infrared sensor ports; These are electronic card ports positioned according to the position of the sensor. Electronic card; It is a PCB card designed to suit the sensor and radiation source positions. Inner perimeter wall; It is a wall designed to separate optical reflections and the infrared sensor from the environmental path. Electronic card fixing slot; It is the slot that allows the electronic card and the infrared radiation source and infrared sensor to be fixed to the optical path body in the correct position. Optical path body fixing holes; It is the pair of holes on the electronic card that allows the electronic card and the optical path body to be fixed together. Infrared radiation source ports; These are electronic card ports positioned according to the position of the infrared radiation source. The invention is an NDlR gas sensor with fixed geometry; It consists of infrared sensor (3), infrared radiation source (2), electronic card (19), optical path body (6) and sensor capsule cover (1). On the electronic card (19); There are connections between the infrared radiation source (2) and the infrared sensor (3). Infrared sensor ports (18) are positioned in accordance with the infrared sensor slot (12) on the electronic card (19), and infrared radiation source ports (23) are positioned in accordance with the infrared radiation source slot (16). In addition, there are 7 electronic card pins (15) on the electronic card (19), where the infrared radiation source (2) and infrared sensor (3) outputs are defined, so that the sensor can be easily operated by connecting it to an electronic reading circuit. The positions of the infrared radiation source (2) and the infrared sensor (3) are fixed on the optical path body (6). The position of the infrared radiation source (2) is fixed within the optical path body (6) by the infrared radiation source slot (16), and the position of the infrared sensor (3) is fixed within the optical path body (6) by the infrared sensor slot (12). The infrared sensor (3) is separated from the environmental path (4) by the inner environmental wall (20). There is also an infrared sensor fixing wall (17) in the infrared sensor housing (12). The front face of the infrared sensor (3) is placed on the infrared sensor fixing wall (17), ensuring the correct positioning of the infrared sensor (3). At the same time, the inner peripheral wall (20) also serves as a reflecting wall for the rays scattered from the infrared radiation source (2). There are 2 electronic card fixing feet (11) at the bottom of the optical path body (6) to fix the electronic card (19) and the optical path body (6) to each other. The electronic card fixing feet (11) are placed into the optical path body fixing holes (22) on the electronic card (19) and ensure that the two parts are fixed to each other. The sensor capsule cover (1) has a structure that surrounds the optical path body (6) and the electronic card (19). There is a gas inlet-outlet hole set (5) on the sensor capsule cover (1) designed to allow gas entry and exit into the sensor capsule. The gas inlet-outlet hole set (5) has a convergent nozzle (narrowing from outside to inside) geometry. Thanks to this geometric structure, the gas diffusion rate is increased while the amount of heat escaping outside the capsule is kept at a minimum level. In order to fix the position of the optical path body (6) within the sensor capsule cover (1) according to the positions of the gas inlet-outlet hole set (5), an optical path body fixing protrusion (14) has been added to the interior of the sensor capsule cover. Likewise, the sensor capsule cover fixing slot (13) where this protrusion will be located is located on the optical path body (6). There is also an electronic card fixing slot (21) on the electronic card (19). Thanks to the electronic card fixing slot (21), it ensures that the electronic card (19) is placed on the optical path body (6) in the correct position, by fixing the positions of the infrared sensor (3) and the infrared radiation source (2). Inside the mounted sensor capsule, the infrared radiation source (2) is a radiation source capable of 3600 radiation. Therefore, a parabolic reflector/focusing wall (9) is placed behind the infrared radiation source housing (16) in order to prevent random scattering and to increase the rate of radiation transmitted to the infrared sensor (3). The infrared radiation source slot (16) is centered at the focal point of the parabolic reflecting/focusing wall (9). Thus, the center of the infrared radiation source (2) is fixed at the same point. The rays scattered from the infrared radiation source (2) follow the optical path (10) and initially proceed along the general optical path (10a). There is a large parabolic reflecting/focusing wall (8) at the end of the general optical path (10a). The large parabolic reflector/focusing wall (8) acts as a parabolic focuser. The majority of the rays reaching the large parabolic reflector/focus wall (8) are reflected from this surface, travel along the radial optical path (1%) and focus on the infrared sensor channels (3a, 3b). Some of the rays scattered from the infrared radiation source (2) are reflected from the large parabolic reflector/focus wall (8) and directed onto the small parabolic reflector/focus wall (7). The small parabolic reflecting/focusing wall (7) ensures that these rays are directed onto the infrared sensor (3). The infrared sensor (3) has two channels: reference channel (3a) and measurement channel (3b). The reference channel (3a) is the infrared sensor (3a) channel, which is not sensitive to the measured gas. The reference channel (3a) takes simultaneous measurements with the measurement channel (3b), preventing incorrect measurements due to environmental factors. The measurement channel (3b) is the infrared sensor channel that is sensitive to the measured gas. The rays scattered from the infrared radiation source (2) interact with the gas molecules and are absorbed if there is a target gas in the environmental path (4). As a result of this event, a change occurs in the radiation intensity reaching the measurement channel (3b) of the infrared sensor (3). According to this change in radiation intensity depending on the presence of the target gas, the infrared sensor (3) produces an electrical signal. Thus, the concentration of the target gas in the environment is measured.TR TR

Claims (1)

1. The invention is an optical gas sensor designed with converging nozzles that detects the gas concentration by monitoring the absorption of infrared radiation of a certain wavelength by the gas sample, and its feature is; The sensor capsule cover (1), which surrounds the optical path and the electronic card and enables the rays to move towards the sensor by reflections thanks to its reflective walls, the infrared radiation source (2), which provides radiation emission at the wavelength required for measurement in the infrared band, the path of the rays scattered from the infrared radiation source (2). Circumferential path (4), which receives and contains a gas sample, gas inlet-outlet hole set (5), designed to ensure rapid gas diffusion by taking advantage of the convergent nozzle geometry and at the same time keeping the amount of heat escaping out of the capsule to a minimum level, and an internal system that contains the infrared sensor and fixes its position. The optical path body (6), which is a cylindrical wall, the small parabolic reflector/focus wall (7), which allows the rays falling on it to be directed to the sensor or onto the parabolic reflector/focus wall opposite it, depending on the angle of incidence, and the large parabolic reflector, which allows to focus the incoming rays on the sensor channels. /focusing wall (8), parabolic reflecting/focusing wall (9), which allows the rays scattered from the radiation source to the opposite side to be reflected to the main path, optical path (10), which allows the rays scattered from the radiation source to reach the sensor, and the optical path (10) and the PCB board are combined and fixed together. electronic card fixing feet (11), infrared sensor slot (12), which allows the sensor to be easily placed and PCB connections to be made, capsule cover fixing slot (13), which ensures that the optical path geometry remains stable and the optical path (10) and the capsule cover are easily combined, the capsule Optical path body fixing protrusion (14), which keeps the optical path geometry constant with its cover and allows it to be easily placed in the recess in the optical path, infrared radiation source slot (15), which is centered on the focal point of the parabolic reflector and indicates the position of the source, allowing placement in the optical capsule, for optical reflections. and it contains an internal peripheral wall (20), preferably of a cylindrical structure, that allows separating the infrared sensor from the environmental path. . The invention is according to Claim 1 and its feature is; It contains the main peripheral optical path (10a), which allows the rays scattered from the radiation source to reach the parabolic focuser, and the radial optical path (1%), which allows the rays reaching the parabolic focuser to be reflected and reach the sensor.