Optical path system for high-temperature flue probe gun

Abstract

An optical path system for a high-temperature flue probe gun comprises a light source, a photoelectric detector, a first lens, a second lens, a beam expander and a pyramid corner angle. The light source and the photoelectric detector are coaxially arranged in parallel; the first lens, the second lens, the beam expanding lens and the pyramid corner angle are all arranged on an output light path of the light source and are coaxial in center, the first lens emits emitted light of the light source in parallel, the second lens converges and emits parallel emergent light of the first lens, the beam expanding lens is arranged behind a convergent light spot of emergent light of the second lens, and the beam expanding lens and the pyramid corner angle are arranged in parallel. The beam expander expands the emergent light of the second lens and emits the light, and after the corner angle of the pyramid reflects the parallel light band emitted by the beam expander, the emitted parallel light sequentially penetrates through the beam expander, the second lens and the first lens and forms a light spot on the cross section of the optical axis where the photoelectric detector is located. The optical path debugging is simple, and the adverse effects of low measurement signal quality or signal loss and the like caused by factors such as mechanical deformation vibration, high-temperature mechanical deformation and the like in the field application of the high-temperature flue probe gun are solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of laser gas detection, and particularly relates to an optical path system for a high-temperature flue gas detection lance. Background Art

[0002] In recent years, it has become particularly important to detect the emissions of pollutants in high-temperature flue gas.

[0003] Due to the irreversible damage of high-temperature environments to electronic components, the high-temperature flue gas detection lance technology based on the laser infrared principle can continuously and online monitor harmful gases in industrial processes and is widely used in many industrial fields. It realizes gas emission detection and process control, such as coal-fired power plants, aluminum plants, steel plants, smelters, waste power plants, cement plants, chemical plants, glass plants, etc.

[0004] Currently, most of the high-temperature flue gas laser infrared detection lances used in the market adopt a combination of a laser infrared light source, a fiber collimator, and a plane mirror. The light source is collimated by the fiber collimator and then emitted, hitting the plane mirror. The positional relationship among the light source, the detector, and the plane mirror is adjusted so that the reflected laser hits the center of the detector. However, since both the emitted light and the received light are point light sources, the debugging is extremely difficult. Moreover, problems such as mechanical deformation and vibration caused by the excessive length of the mechanical lance and mechanical thermal deformation caused by high temperature will cause the optical axes of the light source, the detector, and the plane mirror to shift and deform, resulting in the offset or loss of the point light source hitting the detector, and causing problems such as low measurement signal quality or signal loss of the detector. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the utility model provides an optical path system for a high-temperature flue gas detection lance, which effectively solves the technical problem of difficult optical path debugging in the production of high-temperature flue gas detection lances by expanding the tolerance range of signal emission and signal reception. At the same time, it also effectively solves the adverse effects such as low measurement signal quality or signal loss caused by mechanical deformation and vibration and high-temperature mechanical deformation during the on-site use of high-temperature flue gas detection lances.

[0006] The technical solution adopted by the utility model is as follows.

[0007] An optical path system for a high-temperature flue gas detection lance, comprising a light source, a photodetector, a first lens, a second lens, a beam expander, and a corner cube prism;

[0008] The light source and the photodetector are arranged in parallel and coaxially. The light source uses a laser light source, and the absorption spectrum of the photodetector matches the emission spectrum of the laser light source;

[0009] The first lens, the second lens, the beam expander, and the corner cube prism are all installed on the output optical path of the light source and are coaxial at the center. The first lens collimates the emitted light of the light source and emits it parallelly, which is emitted along the main detection cavity. The second lens converges and emits the parallel light emitted by the first lens. The beam expander is installed after the converging light spot of the light emitted by the second lens. The beam expander expands and emits the light emitted by the second lens. The corner cube prism reflects the parallel light band emitted by the beam expander. The emitted parallel light sequentially passes through the beam expander, the second lens, and the first lens, and forms a light spot on the cross-section of the optical axis where the photodetector is located.

[0010] The first lens and the second lens are respectively installed on both sides of the main cavity of the flue gas detection.

[0011] Preferably, one of the second lens and the beam expander is installed movably along the optical axis direction.

[0012] Preferably, the light source adopts a laser infrared light source.

[0013] Preferably, the first lens adopts a convex lens, and the second lens adopts a concave lens.

[0014] The corner cube prism reflects the incident light in parallel at multiple angles. Through the combined action of the beam expander and the corner cube prism, the reflected light of the corner cube prism is columnar parallel light along the optical axis direction, and a light circle is formed on the cross-section perpendicular to the optical axis. The reflected light of the corner cube prism then passes through the beam expander, the second lens, and the first lens, and forms a light spot on the cross-section of the optical axis where the light source and the photodetector are located. The light source and the photodetector are arranged parallel and coaxial, which means that the emission angle of the light source and the incident angle of the photodetector are parallel and coaxial, ensuring that the reflected light can be received by the photodetector. The reflection mode of the corner cube prism is parallel symmetric reflection, which enables the optical path to return to the coaxial photodetector, increasing the tolerance range of light signal emission and signal reception. As long as the above light spot is irradiated onto the photodetector, that is, the photodetector outputs a detection signal, the debugging is completed. Compared with the dot light that the photodetector in the existing optical path system needs to receive, the debugging is much simpler. Therefore, the present application effectively solves the technical problem of difficult optical path debugging in the production of high-temperature flue gas detection guns by expanding the tolerance range of signal emission and reception. During debugging, by adjusting the front and back positions of the converging light spot, i.e., the focal point, of the light emitted by the second lens, the size of the light circle diverging on the beam expander can be adjusted; or by adjusting the position of the beam expander, the size of the light circle transmitted by the beam expander and diverged by the light emitted by the second lens can be made appropriate.

[0015] Moreover, since the light spot is easier to detect than the light point, even if there are problems such as mechanical deformation tremors caused by the excessive length of the high-temperature flue detection gun or mechanical thermal deformation caused by the high temperature of the flue, the optical signal received by the photodetector is not easily offset or lost. This effectively solves the adverse effects such as low measurement signal quality or signal loss caused by mechanical deformation tremors and high-temperature mechanical deformation during the on-site use of the high-temperature flue detection gun, and improves the stability of signal measurement in the application of the flue detection gun.

[0016] The utility model simplifies the debugging of the optical path, expands the tolerance range of signal transmission and signal reception, solves the adverse effects such as low measurement signal quality or signal loss caused by mechanical deformation tremors and high-temperature mechanical deformation during the on-site application of the high-temperature flue detection gun, and improves the stability of signal measurement. Brief Description of the Drawings

[0017] Figure 1 is the schematic diagram of the optical path of the utility model;

[0018] Figure 2 is the schematic diagram of the working principle of the pyramid corner of the utility model. Detailed Embodiment

[0019] Figure 1 In [the detailed embodiment], 1 is a light source, 2 is a photodetector, 3 is a first lens, 4 is a main detection cavity, 5 is a second lens, 6 is a converging light point, 7 is a beam expander, and 8 is a pyramid corner.

[0020] As Figure 1 shown, an optical path system for a high-temperature flue detection gun of the utility model includes a light source 1, a photodetector 2, a first lens 3, a second lens 5, a beam expander 7, and a pyramid corner 8;

[0021] The light source 1 and the photodetector 2 are arranged in parallel and coaxially. The light source 1 uses a laser light source, and the absorption spectrum of the photodetector 2 matches the emission spectrum of the laser light source;

[0022] The first lens 3, the second lens 5, the beam expander 7, and the pyramid corner 8 are all installed on the output optical path of the light source 1 and are coaxially centered. The first lens 3 emits the light emitted by the light source 1 in parallel and emits it along the main detection cavity 4. The second lens 5 converges and emits the parallel light emitted by the first lens 3. The beam expander 7 is installed after the converging light point 6 of the light emitted by the second lens 5. The beam expander 7 expands and emits the light emitted by the second lens 5. After the pyramid corner 8 reflects the parallel light beam emitted by the beam expander 7, it emits the light in parallel and sequentially passes through the beam expander 7, the second lens 5, and the first lens 3 to form a light spot on the cross-section of the optical axis where the light source 1 and the photodetector 2 are located.

[0023] The first lens 3 and the second lens 5 are respectively installed on both sides of the main cavity for flue gas detection.

[0024] Preferably, one of the second lens 5 and the beam expander 7 is movably installed along the optical axis direction.

[0025] Preferably, the light source 1 uses a laser infrared light source.

[0026] Preferably, the first lens 3 is a convex lens and the second lens is a concave lens.

[0027] In this application, the pyramid edge 8 reflects the incident light in multiple angles in parallel. After the combined action of the beam expander 7 and the pyramid edge 8, the reflected light of the pyramid edge 8 is columnar parallel light along the optical axis direction, and a light circle is formed on the cross-section perpendicular to the optical axis. The reflected light of the pyramid edge 8 then passes through the beam expander 7, the second lens 5, and the first lens 3, and a light spot is formed on the cross-section of the optical axis where the light source 1 and the photodetector 2 are located. The reflection mode of the pyramid prism 8 is parallel symmetric reflection, which enables the optical path to return to the coaxial photodetector 2, increasing the tolerance range of optical signal emission and signal reception. As long as the above light spot is irradiated onto the photodetector 2, that is, the photodetector 2 outputs a detection signal, the debugging is completed. Compared with the dot light that the photodetector 2 in the existing optical path system needs to receive, the debugging is much simpler. Therefore, this application effectively solves the technical problem of difficult optical path debugging in the production of high-temperature flue gas detection guns by expanding the tolerance range of signal emission and reception. During debugging, by adjusting the front and back positions of the converging light point 6, i.e., the focal point, of the light emitted by the second lens 5, the size of the light circle diverging on the beam expander 7 can be adjusted; or by adjusting the position of the beam expander 7, the size of the light circle transmitted by the beam expander 7 and diverged by the light emitted by the second lens 5 can be made appropriate.

[0028] Moreover, since the light spot is easier to detect than the light point, even if there are problems such as mechanical deformation tremors caused by the excessive length of the high-temperature flue gas detection gun or mechanical thermal deformation caused by the high temperature of the flue, the optical signal received by the photodetector 2 is not easily offset or lost, effectively solving the adverse effects such as low measurement signal quality or signal loss caused by mechanical deformation tremors and high-temperature mechanical deformation during the on-site use of the high-temperature flue gas detection gun, and improving the stability of signal measurement in the application of the flue gas detection gun.

[0029] In this embodiment, the first lens 3 and the second lens 5 can also be compound lenses, as long as the second lens 5 can converge parallel light and the first lens 3 can turn the incident light into parallel light. There is no limitation here.

[0030] In this utility model, due to the selected infrared light source, the sizes of the light circle and the light spot are actually not visible, but only for the convenience of description.

[0031] In this embodiment, the specific structure of the high-temperature flue gas detection gun is not given. The optical axis of this utility model is consistent with the direction of the detection gun, which is well-known technology to those skilled in the art.

[0032] As is well known, when applying laser technology to detect gas concentration, the Lambert-Beer law is followed. By applying wavelength modulation technology, only the second harmonic curve of the gas to be measured needs to be measured to measure the concentration of the target gas. The gas concentration is independent of the light intensity. Therefore, even if the photodetector cannot detect the complete reflected light spot, that is, the light spot deviates from the center position of the detector, the detection result is not affected as long as enough light beams pass through for detection.

[0033] Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all embodiments. Any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention all belong to the protection scope of the technical solution of the present invention.

Claims

1. An optical light path system for a high-temperature flue probe gun, characterized in that: It comprises a light source (1), a photodetector (2), a first lens (3), a second lens (5), a beam expander (7) and a pyramid corner (8); The light source (1) and the photodetector (2) are arranged to be parallel and coaxial, the light source (1) is a laser light source, and the absorption spectrum of the photodetector (2) matches the emission spectrum of the laser light source; The first lens (3), the second lens (5), the beam expander (7) and the pyramid edge (8) are all installed on the output light path of the light source (1) and their centers are coaxial. The first lens (3) emits the emitted light of the light source (1) in parallel and emits it along the detection main cavity. The second lens (5) converges and emits the parallel emitted light of the first lens (3). The beam expander (7) is installed behind the convergent light point (6) of the emitted light of the second lens (5). The beam expander (7) expands and emits the emitted light of the second lens (5). After the pyramid edge (8) reflects the parallel light band emitted by the beam expander (7), the emitted parallel light passes through the beam expander (7), the second lens (5) and the first lens (3) in sequence, forming a light spot in the cross section of the optical axis where the light source (1) and the photoelectric detector (2) are located.

2. The optical light path system for a high-temperature flue probe gun according to claim 1, characterized in that: The first lens (3) and the second lens (5) are respectively mounted on two sides of the smoke detection main cavity.

3. The optical light path system for a high-temperature flue probe gun according to claim 1 or 2, characterized in that: One of the second lens (5) and the beam expander (7) is movably mounted along the optical axis.

4. The optical light path system for a high-temperature flue probe gun according to claim 3, characterized in that: The first lens (3) is a convex lens, and the second lens is a concave lens.

Images