A device for measuring the photochemical production rate of reactive atmospheric gases in the environment

Abstract

The application discloses a device for measuring photochemical production rate of active gas in ambient atmosphere, and relates to the fields of atmospheric environment monitoring and automatic control. The device is composed of an air inlet module, a photochemical reaction device, a wideband high-precision cavity measurement system and a control system. The air inlet module injects pure ambient atmosphere or mixed atmosphere with added reaction gas into the photochemical reaction device; the photochemical reaction device is a place where the ambient atmosphere or the mixed atmosphere performs photochemical reaction to produce active gas; the wideband high-precision cavity measurement system samples the mixed atmosphere containing active gas and measures absorption photoelectric signals; and the control system receives the absorption photoelectric signals and performs calculation and processing to obtain the production rate of the active gas. The application has the advantages of automatically and quickly switching to measure the production rate of active gas under photochemical and non-photochemical conditions, and can accurately measure the production rate of active gas outdoors or in a laboratory.

Description

Technical Field

[0001] This invention relates to the fields of atmospheric environment monitoring and automation control, and in particular to a device for measuring the photochemical generation rate of reactive gases in the ambient atmosphere. Background Technology

[0002] Atmospheric reactive gases are important indicators for characterizing local atmospheric photochemical reactions. Accurately measuring the generation rate of reactive gases not only helps analyze whether air pollution is caused by local photochemical generation or external transport, but also helps explore the quantitative relationship with precursors. Therefore, accurately measuring the photochemical generation rate of ambient atmospheric reactive gases is particularly important. Measuring the photochemical generation rate of ambient atmospheric reactive gases requires passing ambient air into a slow-moving, uniformly flowing coarse-flow tube and irradiating the gas inside the tube. To uniformly mix the reactant gas and ambient gas, both gases must be simultaneously passed into a narrow pipe. Because turbulence and uneven flow occur when the airflow flows from the narrow pipe into the coarse pipe, reactive gases are easily lost due to collisions with the walls of the reaction device under turbulent conditions. Furthermore, the uneven flow leads to uneven concentration distribution of photochemical reaction products during both the photochemical reaction and sampling. This results in the measured concentration of reactive gases in the photochemical reaction tube being either too high or too low compared to the actual atmospheric concentration, and the generated reactive gas concentration is very low, making it difficult to measure. Traditional multi-reflection optical cavities are difficult to integrate due to the large size of the adjustment knob and the need for reserved operating space, resulting in a significant lateral length. Therefore, there is currently no suitable flow tube or corresponding active gas measurement device to simulate the photochemical reactions that produce reactive gases in the actual atmosphere, and measurements can only be conducted outdoors on sunny days. Furthermore, previously, to investigate the effect of ultraviolet radiation on the production of reactive gases in photochemical reactions, a UV-blocking film had to be manually applied to the photochemical reaction tube. However, when conducting experiments outdoors, the reaction tube is often installed on rooftops or towers without any obstruction of sunlight, which hinders the manual application or removal of the UV-blocking film. Moreover, the efficiency of manually applying or removing the film is low, making it impossible to achieve the requirement of rapid switching of irradiation wavelengths for measurement. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, this invention provides a device for measuring the photochemical generation rate of reactive gases in ambient air. The device aims to ensure that the gas flow injected into the narrow channel (gas mixing pipe) diffuses evenly and stably into the wider channel (photochemical reaction tube), allowing the ambient air or atmospheric mixture within the photochemical reaction tube to stably and uniformly generate reactive gases under natural or artificial light irradiation. It also enables automatic covering or removal of the ultraviolet cutoff film on the photochemical reaction tube, thereby achieving rapid switching measurement under different wavelengths of natural or artificial light. Finally, a small-volume, high-sensitivity measurement method is employed to accurately measure the generation rate of reactive gases produced in the photochemical reaction tube.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A device for measuring the photochemical generation rate of reactive gases in the ambient atmosphere includes: an air intake module, a photochemical reaction device (1), a broadband high-precision cavity measurement system, and a control system;

[0006] The air intake module is used to inject pure ambient air or an air mixture with added reactive gas into the photochemical reaction device (1);

[0007] The photochemical reaction device (1) is connected to the air intake module and is the site for photochemical reaction of atmospheric mixture. It can also automatically filter out ultraviolet light in the irradiation light.

[0008] The broadband high-precision cavity measurement system is connected to the photochemical reaction device (1) and is used to measure the concentration of active gas generated by the photochemical reaction.

[0009] The control system is used to monitor and control the working status of the air intake module, the photochemical reaction device (1) and the broadband high-precision cavity measurement system. At the same time, it calculates and processes the absorption photoelectric signal output by the broadband high-precision cavity measurement system to finally obtain real-time data on the photochemical generation rate of reactive gases in the ambient atmosphere.

[0010] Furthermore, the air intake module includes: a three-way solenoid valve (2) for controlling whether the reaction gas is introduced, a filter membrane (3) for filtering out particulate matter in the ambient atmosphere, and an air intake flow meter (4) for controlling the flow rate of the reaction gas.

[0011] The ambient air is injected into the photochemical reaction device (1) after passing through the filter membrane (3). The injection of the reaction gas and its mixing with the ambient air are controlled by the three-way solenoid valve (2) and the air inlet flow meter (4).

[0012] Further, the photochemical reaction device (1) includes: a photochemical reaction tube (104) that uniformly diffuses the atmospheric mixture and causes a photochemical reaction; an air inlet wall-penetrating connector (102) connecting the air inlet module and the photochemical reaction tube (104); an upper support (106) for pressing the photochemical reaction tube (104) and supporting the ultraviolet cutoff membrane (107); a lower support (105) for supporting the photochemical reaction tube (104); a xenon lamp tube assembly (101) that provides artificial illumination; an automatic cover film system for automatically switching the irradiation light band; and a reaction device base (103) that carries the above components.

[0013] There are two upper supports (106) for the reaction tube, each in a semi-circular shape with five circular through holes around its perimeter. There are two lower supports (105) for the reaction tube, each in a square shape with the semi-circle removed, and each with a through hole in its lower right part. The photochemical reaction tube (104) is installed between the two upper supports (106) and the two lower supports (105), and its front part is connected to the air intake module through an air intake through-wall connector (102). The xenon lamp assembly (101) consists of a rectangular shell, multiple cylindrical xenon lamps, and four cylindrical support legs. The lower surface of the rectangular shell is coated with a reflective coating, and the axial direction of the cylindrical xenon lamps is aligned with the axial direction of the photochemical reaction tube (104). The reaction device base (103) has a U-shaped guide rail (112), a central gear rotating shaft (111), and a right gear rotating shaft (114) on each of its inner sides. The outer diameter of the U-shaped guide rail (112) is slightly larger than the outer diameter of the upper support (106) of the reaction tube. The center of the central gear rotating shaft (111) has a circular through hole for installing the air inlet wall connector (102). The upper part of the reaction device base (103) has four cylindrical holes. The photochemical reaction tube (104), the upper support (106) of the reaction tube, and the lower support (105) of the reaction tube are installed inside the reaction device base (103). The xenon lamp assembly (101) is installed on the upper part of the photochemical reaction tube (104). The four cylindrical support legs of the xenon lamp assembly (101) are inserted into the four cylindrical holes of the reaction device base (103).

[0014] Furthermore, the photochemical reaction tube (104) includes: a steady-state flow tube (104-1) in which the photochemical reaction occurs; a first-stage diverter (104-2), a second-stage diverter (104-3), and a third-stage diverter (104-4) that uniformly diffuse the atmospheric mixture and generate a plug flow; a three-lobe connecting plate (104-7) for connecting and fixing the three diverter diffusers; an outlet cover plate (104-6) and an outlet pressure plate (104-5) for sealing the photochemical reaction tube (104).

[0015] The front section of the steady-state flow tube (104-1) has a cubic curve shape, while the middle and rear sections are cylindrical. It is made of quartz glass, with a black PFA film coated on the front of the inner surface and a transparent PFA film coated on the rear. Inside the front section of the steady-state flow tube (104-1) are three diverter diffusers with cubic curve cross-sections: a first-stage diverter diffuser (104-2), a second-stage diverter diffuser (104-3), and a third-stage diverter diffuser (104-4), from the outside in. The diffusion angle of the front section of the steady-state flow tube (104-1) and the three diverter diffusers decreases sequentially from the inside out. The three diverter diffusers are made of black PTFE (black polytetrafluoroethylene). The three-bladed connecting plate (104-7) consists of three thin blades with an included angle of 120°, also made of black PTFE, which connects and fixes the three diverter diffusers to the front section of the steady-state flow tube (104-1). The tail end of the steady flow tube (104-1) is sealed by an outlet cover plate (104-6) and an outlet pressure plate (104-5) made of black PTFE. A sealing ring is provided between the outlet cover plate (104-6) and the outlet pressure plate (104-5). The tail end of the outlet cover plate (104-6) is a thin hollow cylinder.

[0016] Furthermore, the automatic film covering system includes: a dual-axis stepper motor (118) providing driving force, a driving gear (115) and a driven gear (113) transmitting driving force, an ultraviolet cutoff membrane (107) that can filter out the ultraviolet band of natural light or xenon lamp light, a film pulling rod (108) that pulls the ultraviolet cutoff membrane (107) to move, a U-shaped guide rail (112) that guides the film pulling rod (108) to move along a fixed trajectory, a connecting rod gear (110) and a telescopic sleeve rod (109) that cause the film pulling rod (108) to drive the ultraviolet cutoff membrane (107) to move along the trajectory of the U-shaped guide rail (112), a central gear rotating shaft (111) that mounts the connecting rod driving gear, a right gear rotating shaft (114) that mounts the driven gear (113), a roller (117) and a coil spring (116) for straightening the ultraviolet cutoff membrane (107), and a support rod (119) for supporting the shape of the ultraviolet cutoff membrane (107).

[0017] The two output shafts of the dual-axis stepper motor (118) extend from the through holes opened at the lower right of the two reaction tube support brackets (105). There are two driving gears (115), which are respectively installed at both ends of the dual-axis stepper motor (118); there are two driven gears (113), which are respectively installed on the right gear rotating shafts (114) on both sides of the reaction device base (103); there are two connecting gears (110), which are respectively installed on the middle gear rotating shafts (111) on both sides of the reaction device base (103); the driven gears (113) mesh with the driving gears (115) and the connecting gears (110), the driving gears (115) and the driven gears (113) have the same number of teeth, and the connecting gears (110) have a greater number of teeth than the driving gears (115) and the driven gears (113); the connecting gears (110) are composed of an incomplete gear with a circular through hole in the middle and a telescopic cylinder fixed on the incomplete gear. There are two telescopic sleeves (109), which are composed of a telescopic rod and a sleeve fixed to the end of the telescopic rod. The telescopic sleeve (109) is inserted into the telescopic cylinder of the connecting gear (110), and the film-pulling rod (108) is inserted into the sleeve at the end of the telescopic sleeve (109). One end of the ultraviolet cutoff membrane (107) is fixed to the film-pulling rod (108), and the other end is fixed to the roller (117). Two coil springs (116) are respectively installed at both ends of the roller (117) and fixed to the left side of the reaction device base (103). A limit switch is provided at both ends of the U-shaped guide rail (112). The two ends of the film-pulling rod (108) are respectively inserted into the U-shaped guide rails on both sides of the reaction device base (103). There are five support rods (119), which are respectively installed in the five circular through holes opened around the periphery of the support (106) on the reaction tube.

[0018] Furthermore, the broadband high-precision cavity measurement system includes: a semiconductor light source (16) emitting broadband light in the absorption band of the active gas to be measured; a driving circuit board (17) supplying power to the semiconductor light source (16) and controlling its temperature; a collimating lens (15) that converts the diverging light emitted by the semiconductor light source (16) into parallel light; an aperture (14) that filters out stray light at the edge of the parallel light; a first reflector (13) and a second reflector (12) that deflect the light path by 180°; and a precision optical cavity that causes multiple reflections of the broadband light. (11) A filter (7) for filtering out broadband light and excess wavelength light in ambient light; a focusing lens (18) for focusing broadband light emitted from the precision optical cavity (11); a photomultiplier tube (19) for photoelectric conversion of the focused broadband light; a pressure gauge (10) for real-time monitoring of the internal pressure of the precision optical cavity (11); a gas pump (8) for pumping gas from the photochemical reaction device (1) into the precision optical cavity (11); and a pumping flow meter (9) for controlling the pumping speed of the gas pump (8).

[0019] Following the semiconductor light source (16) in the broadband light propagation direction are: collimating lens (15), aperture (14), first reflector (13), second reflector (12), precision optical cavity (11), filter (7), focusing lens (18), and photomultiplier tube (19). The filter (7) is a narrowband filter, and a light-shielding tube is provided on the outside of the focusing lens (18) and the filter (7).

[0020] Furthermore, the precision optical cavity (11) includes: a high-reflection mirror (1101) that causes broadband light to reflect back and forth multiple times, a high-reflection mirror pressure plate (1102) for pressing the high-reflection mirror (1101), a gas flow optical cavity (1103) for irradiating gas with broadband light, and a threaded adjustment knob (1104) for adjusting the angle of the high-reflection mirror (1101).

[0021] The gas flow optical cavity (1103) is a hollow cylindrical cavity that is thicker at both ends and thinner in the middle. Its upper left and upper right parts are respectively provided with pipes that are perpendicularly connected to it, serving as an inlet pipe and an outlet pipe. The inlet pipe is connected to the thin hollow cylinder at the tail end of the outlet cover plate (104-6). The outlet pipe is connected to the pressure gauge (10) and the pump flow meter (9) connected to the air pump (8) via a tee. Three small through holes of equal arc length are respectively opened on the inner side of both ends of the gas flow optical cavity (1103). There are two high-reflectivity mirrors (1101), symmetrically installed inside both sides of the gas flow optical cavity (1103), with their high-reflectivity mirror surfaces facing each other. A high-elasticity sealing ring is provided between the high-reflectivity mirror (1101) and the gas flow optical cavity (1103) to seal both ends of the gas flow optical cavity (1103) and to provide elastic restoring force to the high-reflectivity mirror (1101). The high-reflectivity mirror pressure plate (1102) is disc-shaped with a through hole in its center. The diameter of the through hole is slightly smaller than the outer diameter of the high-reflectivity mirror (1101). Three fine-threaded holes of equal arc length are formed around the perimeter of the high-reflectivity mirror pressure plate (1102). There are two high-reflectivity mirror pressure plates (1102), symmetrically installed on both sides of the gas flow optical cavity (1103). A cylindrical groove is formed on the inner side of the high-reflectivity mirror pressure plate (1102) to hold the high-reflectivity mirror (1101). The outer diameter of the high-reflectivity mirror pressure plate (1102) is equal to the outer diameter of both ends of the gas flow optical cavity (1103). A cylindrical step is formed on the outer periphery of the high-reflectivity mirror pressure plate (1102). The diameter of the cylindrical step is slightly smaller than the inner diameter of both ends of the gas flow optical cavity (1103). The cylindrical step extends into the interior of both ends of the gas flow optical cavity (1103) by a distance (approximately 5 mm). There are six threaded adjustment knobs (1104), which are located on the inner side of both ends of the gas flow optical cavity (1103). They pass through three small through holes on the inner side of both ends of the gas flow optical cavity (1103) and are screwed onto three fine threaded holes opened around the periphery of the high-reflection mirror pressure plate (1102).

[0022] Furthermore, the control system includes an industrial computer (6) and a microcontroller (5).

[0023] The industrial control computer (6) directly receives the signal from the pressure gauge (10). The industrial control computer (6) directly controls the air intake flow meter (4), the air extraction flow meter (9), and the drive circuit board (17). The industrial control computer (6) indirectly controls the switch of the air pump (8) through the microcontroller (5). The microcontroller (5) receives the signal from the limit switch installed at both ends of the U-shaped guide rail (112) and controls the forward and reverse rotation of the dual-axis stepper motor (118). The microcontroller (5) controls the opening and closing of the three-way solenoid valve (2). The microcontroller (5) receives the signal from the pressure gauge (10) and the photomultiplier tube (19) and uploads it to the industrial control computer (6).

[0024] In this invention, the narrowband filter is a bandpass filter with a relatively narrow passband (the range of wavelengths that can be passed), generally less than 5% of the center wavelength value.

[0025] The advantages of this invention are:

[0026] (1) The device of the present invention can achieve uniform diversion and stable diffusion of gas injected into the coarse pipe (photochemical reaction tube) through the fine pipe (gas mixing pipe), so that the airflow in the coarse pipe can be pushed forward evenly and stably, thereby reducing the turbulent loss of active gas and making the flow time of atmospheric mixture in the photochemical reaction tube more uniform and stable.

[0027] (2) The device of the present invention can generate stable active gas by irradiating the photochemical reaction tube with sunlight outdoors and measure it, and can also generate stable active gas by irradiating the photochemical reaction tube with xenon lamp in the laboratory and measure it, so that photochemical reaction experiments can be carried out at night or on rainy days.

[0028] (3) The photochemical reaction tube of the device of the present invention is made of quartz glass, and the front part of the inner surface is coated with a black PFA film, and the rear part of the inner surface is coated with a transparent PFA film. The three diverter diffusers and the three-lobe connecting plate located at the front end of the photochemical reaction tube are all made of black PTFE. Such material selection and design can ensure that natural light or xenon lamp light can only irradiate the stable flow zone of the photochemical reaction tube, and can reduce the loss of active gas due to wall friction caused by the material.

[0029] (4) The device of the present invention can realize fully automatic and rapid operation of covering or removing the ultraviolet cut-off membrane, avoiding the inconvenience of manual operation caused by the installation position. It can also realize rapid switching measurement of different irradiation bands in a short period of time. The present invention can obtain two sets of measurement data with different irradiation bands in one day using only one photochemical reaction tube, which is convenient for the analysis and understanding of environmental atmospheric photochemical processes.

[0030] (5) The device of the present invention is based on the principle of long optical path absorption, which can realize the accurate measurement of low concentration of reactive gases. Moreover, the device of the present invention uses a combination of semiconductor light source and narrow band filter as the absorption light source for reactive gases. Compared with traditional lasers, it is low in cost and small in size, so as to facilitate the replacement of light sources or filters of different wavelengths to measure the generation rate of different types of reactive gases.

[0031] (6) The precision optical cavity of the device of the present invention adopts the high-reflection mirror reverse pull adjustment method, and sets the large-volume threaded adjustment knob on the inner side of both ends of the optical cavity. The horizontal length is shortened by utilizing the spare volume on the inner side of both ends of the optical cavity, which has the advantages of small size and simple structure. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the structure of a device for measuring the photochemical generation rate of reactive gases in the ambient atmosphere provided in an embodiment of the present invention;

[0034] Figure 2 This is an isometric view of the photochemical reaction device provided in an embodiment of the present invention;

[0035] Figure 3 This is a front view of the photochemical reaction apparatus provided in an embodiment of the present invention;

[0036] Figure 4 This is an isometric view of the automatic film covering system provided in an embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram of the structure and assembly of the connecting rod gear and telescopic sleeve provided in an embodiment of the present invention;

[0038] Figure 6 This is a front cross-sectional view of the photochemical reaction tube provided in an embodiment of the present invention;

[0039] Figure 7 This is a side cross-sectional view of the photochemical reaction tube provided in an embodiment of the present invention;

[0040] Figure 8 This is an isometric view of the precision optical cavity provided in an embodiment of the present invention;

[0041] Figure 9 This is a front cross-sectional view of the precision optical cavity provided in an embodiment of the present invention;

[0042] The meanings of the reference numerals in the attached figures are as follows:

[0043] 1-Photochemical reaction apparatus, 101-Xenon lamp assembly, 102-Inlet wall-penetrating connector, 103-Reaction apparatus base, 104-Photochemical reaction tube, 104-1-Steady-state flow tube, 104-2-First-stage split diffuser, 104-3-Second-stage split diffuser, 104-4-Third-stage split diffuser, 104-5-Outlet pressure plate, 104-6-Outlet cover plate, 104-7-Three-lobe connecting plate, 105-Lower support for reaction tube, 106-Upper support for reaction tube, 107-UV cutoff membrane, 108-Tightening rod, 109-Telescopic sleeve rod, 110-Connecting rod and gear, 111-Central gear rotating shaft, 112-U-shaped guide rail, 113-Driven gear, 11 4-Right gear rotating shaft, 115-Drive gear, 116-Coil spring, 117-Coil shaft, 118-Dual-axis stepper motor, 119-Support rod, 2-Three-way solenoid valve, 3-Filter membrane, 4-Inlet flow meter, 5-Microcontroller, 6-Industrial control computer, 7-Filter, 8-Air pump, 9-Pump flow meter, 10-Pressure gauge, 11-Precision optical cavity, 1101-High-reflectivity mirror, 1102-High-reflectivity mirror pressure plate, 1103-Gas flow optical cavity, 1104-Threaded adjustment knob, 12-Second reflector, 13-First reflector, 14-Aperture, 15-Collimating lens, 16-Semiconductor light source, 17-Drive circuit board, 18-Focusing lens, 19-Photomultiplier tube. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, similar structures or other embodiments designed by those skilled in the art without creative effort are all within the scope of protection of the present invention.

[0045] Please see Figure 1 , Figure 2 , Figure 4 , Figure 6 , Figure 7 and Figure 8A device for measuring the photochemical generation rate of reactive gases in ambient air includes: an air intake module, a photochemical reaction device 1, a broadband high-precision cavity measurement system, and a control system. The air intake module includes a three-way solenoid valve 2, a filter membrane 3, and an air intake flow meter 4, used to mix ambient air with the reaction gas. The photochemical reaction device 1 includes: a photochemical reaction tube 104, an air intake through-wall connector 102, an upper support 106 for the reaction tube, a lower support 105 for the reaction tube, a xenon lamp assembly 101, an automatic membrane covering system, and a reaction device base 103, which is the site for the photochemical reaction of the atmospheric mixture. The automatic film covering system includes: a dual-axis stepper motor 118, a drive gear 115, a driven gear 113, a right gear rotating shaft 114, an ultraviolet cutoff membrane 107, a film pulling rod 108, a U-shaped guide rail 112, a connecting rod gear 110, a middle gear rotating shaft 111, a telescopic sleeve rod 109, a roller 117, a coil spring 116, and a support rod 119, used for quickly and automatically covering or removing the ultraviolet cutoff membrane 107 from the photochemical reaction tube 104. The broadband high-precision cavity measurement system includes: a semiconductor light source 16, a drive circuit board 17, a collimating lens 15, an aperture 14, a first reflector 13, a second reflector 12, a precision optical cavity 11, a filter 7, a focusing lens 18, a photomultiplier tube 19, a pressure gauge 10, an air pump 8, and a pumping flow meter 9, used for measuring the concentration of reactive gases generated by the photochemical reaction. The precision optical cavity 11 includes: a high-reflection mirror 1101, a high-reflection mirror pressure plate 1102, a gas flow optical cavity 1103, and a threaded adjustment knob 1104, used to cause broadband light to be reflected multiple times, thereby enabling the reactive gas to undergo long-path absorption. The control system includes: an industrial computer 6 and a microcontroller 5, used to monitor and control the working status of the gas inlet module, the photochemical reaction device 1, and the broadband high-precision cavity measurement system, and to perform calculations and processing on the photoelectric signals output by the broadband high-precision cavity measurement system.

[0046] See Figure 1The filter membrane 3 and the air inlet flow meter 4 are located at the front end of the device of the present invention, the photochemical reaction device 1 is located in the middle of the device of the present invention, and the precision optical cavity 11 is located at the rear end of the device of the present invention. The filter membrane 3 and the inlet flow meter 4 are connected to the inlet end of the steady-state flow tube 104-1 in the photochemical reaction device 1 after the gas path is combined through the three-way solenoid valve 2. The inlet pipe of the precision optical cavity 11 is connected to the hollow cylinder at the tail end of the outlet cover plate 104-6 in the photochemical reaction device 1. The semiconductor light source 16 is placed parallel to the precision optical cavity 11. The broadband light emitted by the semiconductor light source 16 passes through the collimating lens 15, the aperture 14, the first reflector 13, and the second reflector 12 in sequence and enters from one end of the precision optical cavity 11. The broadband light exits from the other end of the precision optical cavity 11 and is focused onto the photomultiplier tube 19 by the filter 7 and the focusing lens 18. The outlet pipe of the precision optical cavity 11 is connected to one end of the pump flow meter 9 and the pressure gauge 10. The other end of the pump flow meter 9 is connected to the air pump 8. The industrial control computer 6 is connected to the air intake flow meter 4, the microcontroller 5, the air extraction flow meter 9, the pressure gauge 10 and the drive circuit board 17 via signal lines. The microcontroller 5 is connected to the three-way solenoid valve 2, the air pump 8, the photomultiplier tube 19, the limit switches at both ends of the U-shaped guide rail 112 in the photochemical reaction device 1 and the dual-axis stepper motor 118 via signal lines. The drive circuit board 17 is connected to the semiconductor light source 16 via power lines.

[0047] The air intake module includes: a three-way solenoid valve 2 for controlling whether the reaction gas is introduced, a filter membrane 3 for filtering out particulate matter in the ambient air, and an air intake flow meter 4 for controlling the flow rate of the reaction gas. Specifically, the ambient air is injected into the photochemical reaction device 1 after passing through the filter membrane 3, and the injection of the reaction gas and its mixing with the ambient air are controlled by the three-way solenoid valve 2 and the air intake flow meter 4.

[0048] See Figure 2 , Figure 3 and Figure 4 The photochemical reaction device 1 includes: a photochemical reaction tube 104 that uniformly diffuses the atmospheric mixture and causes a photochemical reaction; an air inlet wall-penetrating connector 102 that connects the air inlet module to the photochemical reaction tube 104; an upper support 106 that presses the photochemical reaction tube 104 and supports the ultraviolet cutoff membrane 107; a lower support 105 that supports the photochemical reaction tube 104; a xenon lamp tube assembly 101 that provides artificial light; an automatic membrane covering system; and a reaction device base 103.

[0049] Specifically, the upper support 106 of the reaction tube is semi-circular in shape, with five circular through holes around its perimeter. The lower support 105 of the reaction tube is square in shape with the semi-circle removed, and has a through hole in its lower right part. The xenon lamp assembly 101 consists of a rectangular shell, multiple cylindrical xenon lamps, and four cylindrical support legs. The lower surface of the rectangular shell is coated with reflective paint, and the axis of the cylindrical xenon lamps is aligned with the axis of the photochemical reaction tube 104. The reaction device base 103 has a U-shaped guide rail 112, a central gear rotating shaft 111, and a right gear rotating shaft 114 on each of its inner ends. The outer diameter of the U-shaped guide rail 112 is slightly larger than the outer diameter of the upper support 106 of the reaction tube. The center of the central gear rotating shaft 111 has a circular through hole for installing the air inlet wall-penetrating connector 102. The upper part of the reaction device base 103 has four cylindrical holes. The photochemical reaction tube 104, the upper support 106 and the lower support 105 are installed inside the reaction device base 103. The xenon lamp assembly 101 is installed on the upper part of the photochemical reaction tube 104. The four cylindrical support legs of the xenon lamp assembly 101 are inserted into the four cylindrical holes of the reaction device base 103.

[0050] Furthermore, there are two upper support 106 and two lower support 105 for the reaction tube. The upper support 106 and the lower support 105 on the left side are aligned and clamp the photochemical reaction tube 104. Figure 4 To the left and right of the dashed line, the upper support 106 and lower support 105 of the reaction tube are aligned and clamp the photochemical reaction tube 104. Figure 4 The left side of the central air pressure plate 104-5. The photochemical reaction tube 104 is installed between the upper support 106 and the lower support 105 of the two reaction tubes, and its front part is connected to the air intake module through the air intake through-wall connector 102.

[0051] See Figure 6 and Figure 7 The photochemical reaction tube 104 includes: a steady-state flow tube 104-1 in which a photochemical reaction occurs; a first-stage diverter diffuser 104-2, a second-stage diverter diffuser 104-3, and a third-stage diverter diffuser 104-4 that uniformly diffuse the atmospheric mixture and generate a plug flow; a three-lobe connecting plate 104-7 for connecting and fixing the three diverter diffusers; an outlet cover plate 104-6 and an outlet pressure plate 104-5 that seal the photochemical reaction tube 104.

[0052] Specifically, see Figure 6The steady-state flow tube 104-1 has a cubic curve cross-section on the left side of the dotted line and a cylindrical cross-section on the right side. It is made of quartz glass, with a black PFA layer coated on the inner surface on the left side and a transparent PFA layer coated on the inner surface on the right side. Inside the steady-state flow tube 104-1 on the left side of the dotted line are three flow divider diffusers with cubic curve cross-sections: a first-stage flow divider diffuser 104-2, a second-stage flow divider diffuser 104-3, and a third-stage flow divider diffuser 104-4, from the outside in. The three flow divider diffusers are made of black PTFE. The diffusion angle of the steady-state flow tube 104-1 and the three flow divider diffusers decreases sequentially from the inside out. The right sides of the three flow divider diffusers are aligned with the dotted line. The tail end of the steady flow tube 104-1 is sealed by an outlet cover plate 104-6 and an outlet pressure plate 104-5 made of black PTFE. A sealing ring is provided between the outlet cover plate 104-6 and the outlet pressure plate 104-5. The tail end of the outlet cover plate 104-6 is a thin hollow cylinder.

[0053] Further, see Figure 7 The three-bladed connecting plate 104-7 consists of three thin blades with an included angle of 120°, and is made of black PTFE. It connects and fixes the three flow diffusers to the steady flow tube 104-1.

[0054] See Figure 4 and Figure 5 The automatic film covering system includes: a dual-axis stepper motor 118 providing driving force, a driving gear 115 and a driven gear 113 transmitting driving force, an ultraviolet cutoff membrane 107 that can filter out the ultraviolet band of natural light or xenon lamp light, a film pulling rod 108 that pulls the ultraviolet cutoff membrane 107, a U-shaped guide rail 112 that guides the film pulling rod 108 to move along a fixed trajectory, a connecting rod gear 110 and a telescopic sleeve rod 109 that cause the film pulling rod 108 to drive the ultraviolet cutoff membrane 107 to move along the trajectory of the U-shaped guide rail 112, a central gear rotating shaft 111 for mounting the connecting rod driving gear 110, a right gear rotating shaft 114 for mounting the driven gear 113, a roller 117 and a coil spring 116 for straightening the ultraviolet cutoff membrane 107, and a support rod 119 for supporting the shape of the ultraviolet cutoff membrane 107.

[0055] Specifically, the two output shafts of the dual-axis stepper motor 118 extend from the through holes opened at the lower right of the two reaction tube support brackets 105. There are two driving gears 115, respectively mounted at both ends of the dual-axis stepper motor 118; two driven gears 113, respectively mounted on the right gear rotating shafts 114 on both sides of the reaction device base 103; and two connecting rod gears 110, respectively mounted on the middle gear rotating shafts 111 on both sides of the reaction device base 103. The driven gears 113 mesh with the driving gears 115 and the connecting rod gears 110. The driving gears 115 and 113 have the same number of teeth, while the connecting rod gear 110 has a greater number of teeth than both the driving gears 115 and 113. The connecting rod gear 110 consists of an incomplete gear with a circular through hole in the middle and a telescopic cylinder fixed to the incomplete gear. There are two telescopic sleeves 109, each consisting of a telescopic rod and a sleeve fixed to the end of the telescopic rod. The telescopic sleeve 109 is inserted into the telescopic cylinder of the connecting rod gear 110, and the film-pulling rod 108 is inserted into the sleeve at the end of the telescopic sleeve 109. One end of the ultraviolet cutoff membrane 107 is fixed to the film-pulling rod 108, and the other end is fixed to the roller 117. Two coil springs 116, fixed to the left side of the reaction device base 103, are respectively installed at both ends of the roller 117. A limit switch is provided at both ends of the track of the U-shaped guide rail 112. The two ends of the film-pulling rod 108 are respectively inserted into the U-shaped guide rails 111 on both sides of the reaction device base 103. There are five support rods 119, which are respectively installed in the five circular through holes opened around the periphery of the support 106 on the reaction tube.

[0056] Further, see Figure 3 The drive gear 115, driven gear 113, connecting rod gear 110, telescopic sleeve 109, U-shaped guide rail 112, and coil spring 116 each have two components, and are arranged in a specific order. Figure 3 Using the dotted line as a reference, the installation is symmetrical, meaning the installation angles are consistent, so that the film-pulling rod 108, inserted into the sleeve at the end of the telescopic sleeve 109, always moves along the U-shaped guide rail 112 parallel to the central axis of the photochemical reaction tube 104.

[0057] See Figure 1The broadband high-precision cavity measurement system includes: a semiconductor light source 16 that emits broadband light in the absorption band of the active gas to be measured; a drive circuit board 17 that powers the semiconductor light source 16 and generates a modulation signal; a collimating lens 15 that converts the divergent light emitted by the semiconductor light source 16 into parallel light; an aperture 14 that filters out stray light at the edge of the parallel light; a first reflector 13 and a second reflector 12 that deflect the light path by 180°; a precision optical cavity 11 that causes multiple reflections of the broadband light; a filter 7 that filters out broadband light and excess wavelength light in the ambient light; a focusing lens 18 that focuses the broadband light emitted from the precision optical cavity 11; a photomultiplier tube 19 that performs photoelectric conversion on the focused broadband light; a pressure gauge 10 that monitors the internal pressure of the precision optical cavity 11 in real time; a gas pump 8 that draws gas from the photochemical reaction device 1 into the precision optical cavity 11; and a pumping flow meter 9 that controls the pumping speed of the gas pump 8.

[0058] Specifically, following the semiconductor light source 16, in the order of broadband light propagation direction, are: collimating lens 15, aperture 14, first reflector 13, second reflector 12, precision optical cavity 11, filter 7, focusing lens 18, and photomultiplier tube 19. Filter 7 is a narrowband filter, and a light-shielding tube is provided on the outside of focusing lens 18 and filter 7.

[0059] See Figure 8 and Figure 9 The precision optical cavity 11 includes: a high-reflection mirror 1101 that causes broadband light to reflect back and forth multiple times, a high-reflection mirror pressure plate 1102 for pressing the high-reflection mirror 1101, a gas flow optical cavity 1103 for irradiating gas with broadband light, and a threaded adjustment knob 1104 for adjusting the angle of the high-reflection mirror 1101.

[0060] Specifically, the gas flow optical cavity 1103 is a hollow cylindrical cavity that is thicker at both ends and thinner in the middle. Its upper left and upper right parts each have a vertically connected pipe, serving as an inlet pipe and an outlet pipe, respectively. The inlet pipe is connected to the thin hollow cylinder at the tail end of the outlet cover plate 104-6. The outlet pipe is connected to the pressure gauge 10 and the air flow meter 9 connected to the air pump 8 via a tee. Three small through holes of equal arc length are formed on the inner sides of both ends of the gas flow optical cavity 1103. There are two high-reflectivity mirrors 1101, symmetrically installed inside both sides of the gas flow optical cavity 1103, with their high-reflectivity mirror surfaces facing each other. A high-elasticity sealing ring is provided between the high-reflectivity mirrors 1101 and the gas flow optical cavity 1103 to seal both ends of the gas flow optical cavity 1103 and provide elastic restoring force to the high-reflectivity mirrors 1101. The high-reflectivity mirror pressure plate 1102 is disc-shaped with a through hole in its center. The diameter of the through hole is slightly smaller than the outer diameter of the high-reflectivity mirror 1101. The high-reflection mirror pressure plate 1102 has three fine-threaded holes of equal arc length around its circumference. There are two high-reflection mirror pressure plates 1102, symmetrically installed on both sides of the gas flow optical cavity 1103. A cylindrical groove is formed on the inner side of the high-reflection mirror pressure plate 1102 to hold the high-reflection mirror 1101 in place. The outer diameter of the high-reflection mirror pressure plate 1102 is equal to the outer diameter of both ends of the gas flow optical cavity 1103. A cylindrical step is formed on the outer periphery of the high-reflection mirror pressure plate 1102. The diameter of the cylindrical step is slightly smaller than the inner diameter of both ends of the gas flow optical cavity 1103, and the cylindrical step extends approximately 5mm into the interior of both ends of the gas flow optical cavity 1103, serving a dustproof function. Six threaded adjustment knobs 1104 are located on the inner side of both ends of the gas flow optical cavity 1103, passing through three small through holes on the inner side of both ends of the gas flow optical cavity 1103 and screwed onto the three fine-threaded holes around the circumference of the high-reflection mirror pressure plate 1102.

[0061] See Figure 1 The control system includes an industrial computer (6) and a microcontroller (5).

[0062] Specifically, the industrial control computer 6 directly receives the signal from the pressure gauge 10, directly controls the air intake flow meter 4, the air extraction flow meter 9, and the drive circuit board 17, indirectly controls the switch of the air pump 8 through the microcontroller 5, receives the signal from the limit switches installed at both ends of the U-shaped guide rail 112 and controls the forward and reverse rotation of the dual-axis stepper motor 118, controls the opening and closing of the three-way solenoid valve 2, and receives the signal from the pressure gauge 10 and the photomultiplier tube 19 and uploads it to the industrial control computer 6.

[0063] In this invention, the principle of using an ambient atmospheric reactive gas photochemical generation rate measuring device to induce a photochemical reaction in ambient atmosphere or atmospheric mixtures to produce reactive gases, and measuring the generation rate of the reactive gases, is as follows:

[0064] (1) When only the generation rate of reactive gases produced by ambient air under illumination is measured, the industrial control computer 6 controls the operation of the air pump flow meter 9 and sets a suitable flow rate. The industrial control computer 6 controls the operation of the air pump 8 through the microcontroller 5 and controls the reaction gas path of the three-way solenoid valve 2 to close. The ambient air is filtered through the filter membrane 3 and then introduced into the photochemical reaction tube 104 through the inlet wall connector 102. When it is necessary to measure the effect of a certain gas on the generation rate of reactive gases produced by ambient air under illumination, the industrial control computer 6 controls the operation of the air pump flow meter 4 and sets a suitable flow rate. The industrial control computer 6 controls the reaction gas path of the three-way solenoid valve 2 to open through the microcontroller 5. The mixture of ambient air and reaction gas is introduced into the photochemical reaction tube 104 through the inlet wall connector 102. Since there are solid particles such as dust and PM2.5 in the ambient atmosphere, these solid particles will adhere to the inner surface of the photochemical reaction tube 104 of the present invention and the reflective surface of the high-reflection mirror 1101 in the precision optical cavity 11. This will cause the light transmittance of the photochemical reaction tube 104 and the reflectance of the high-reflection mirror 1101 to gradually decrease. Therefore, by setting a filter membrane 3 at the sampling port of the ambient atmosphere, the occurrence of such situations can be greatly reduced.

[0065] (2) After the ambient air or atmospheric mixture is introduced into the photochemical reaction tube 104, the airflow diffuses after entering the inlet end of the steady-state flow tube 104-1, with the velocity at the center being greater than that at the periphery. After diffusing a certain distance, the airflow encounters the first-stage split diffuser 104-2, where it is divided into two parts: the fast airflow at the center enters the space inside the first-stage split diffuser 104-2, while the slow airflow at the periphery enters the space inside the steady-state flow tube 104-1 and outside the first-stage split diffuser 104-2. The slow airflow at the periphery is pulled into a plug flow that is nearly parallel to the axis of the photochemical reaction tube 104 after passing through the space with a cubic curve at the edge. The fast airflow at the center is pulled into a plug flow that is nearly parallel to the axis of the photochemical reaction tube 104 after passing through the second-stage split diffuser 104-3 and the third-stage split diffuser 104-4, according to the above principle. Because the diffusion angles of the front part of the steady-state flow tube 104-1 and the three diverter diffusers decrease sequentially from the inside to the outside, the diffusion angle of the innermost third-stage diverter diffuser 104-4 is close to the natural diffusion angle of the airflow. Therefore, the fast airflow in the center will diffuse naturally in the third-stage diverter diffuser 104-4. However, influenced by the airflows flowing out of the second-stage diverter 104-3 and the third-stage diverter diffuser 104-4, the airflow flowing out of the third-stage diverter diffuser 104-4 will also flow forward almost parallel to the axis of the photochemical reaction tube 104. Because the inlet of the steady-state flow tube 104-1 and the three diverter diffusers decrease sequentially from the inside to the outside, the airflow velocities flowing out of the four partitioned spaces are basically equal. Finally, through the design of the air inlet of the photochemical reaction tube 104 of this invention, smooth diffusion and uniform propulsion from the thin pipe to the thick pipe can be achieved, and the turbulence loss of the active gas is also reduced.

[0066] (3) When a photochemical generation rate measurement experiment is required using natural light, remove the xenon lamp assembly 101 from the reaction device base 103 and place the photochemical reaction device 1 outdoors without sunlight obstruction, allowing natural light to illuminate the surface of the photochemical reaction tube 104. When a photochemical generation rate measurement experiment needs to be conducted indoors due to poor natural light conditions or other factors, install the xenon lamp assembly 101 onto the reaction device base 103 and place the photochemical reaction device 1 indoors in darkness, turn on the xenon lamp assembly 101, and allow the xenon light to illuminate the surface of the photochemical reaction tube 104. Place the photochemical reaction device 1 outdoors or in a laboratory and turn on the xenon lamp assembly 101 to irradiate the atmospheric mixture inside the photochemical reaction tube 104. The atmospheric mixture will generate a certain concentration of active gas under illumination. Since the steady-state flow tube 104-1 is made of quartz glass with a black PFA layer coated on the front and a transparent PFA layer coated on the back of the inner surface, and the material of the three diverter diffusers is black PTFE, and the right side of the three diverter diffusers is aligned with the gas flow smooth diffusion line ( Figure 5Alignment with the dashed lines shown allows for stable diffusion flow only within the photochemical reaction tube 104. Figure 5 The area to the right of the dotted line shown is illuminated. Since the surfaces in contact with the active gas and the photochemical reaction tube 104 are all made of PFA or PTFE, the wall loss of the active gas due to the material is very small.

[0067] (4) When it is necessary to study the effect of ultraviolet light on the photochemical generation rate of reactive gases, the microcontroller 5 controls the dual-axis stepper motor 118 to rotate forward. The dual-axis stepper motor 118 drives the two active gears 115 to rotate synchronously. The two active gears 115 drive the two connecting rod gears 110 to rotate through the two driven gears 113. At this time, the telescopic sleeve 109 installed in the connecting rod gear 110 will drive the film-pulling rod 108 to move along the trajectory of the U-shaped guide rail 112. Since there are two of each of the active gear 115, driven gear 113, connecting rod gear 110, telescopic sleeve 109, and U-shaped guide rail 112, and... Figure 3Using the dotted lines as a reference, the components are symmetrically arranged, ensuring that the film-pulling rod 108 remains parallel to the central axis of the photochemical reaction tube 104 during movement. Since one end of the UV-blocking membrane 107 is fixed to the film-pulling rod 108 and the other end to a roller 117 with coil springs 116 at both ends, when the dual-axis stepper motor 118 rotates forward, it pulls the roller 117, which is wound with the UV-blocking membrane 107, to rotate. This causes the UV-blocking membrane 107 to gradually cover the periphery of the five support rods 119 mounted on the reaction support. When the film-pulling rod 108 reaches the end of the U-shaped guide rail 112 and touches the limit switch, the microcontroller 5 receives the signal from the limit switch and shuts off the dual-axis stepper motor 118. At this point, the UV-blocking membrane 107 covers the outer surface of the photochemical reaction tube 104, filtering out the UV wavelengths from natural light or xenon lamp light. In this design, the incomplete gear on the connecting rod 110 has only a few teeth removed, and its number of teeth is greater than that of the driving gear 115. Therefore, during the transmission process from the dual-axis stepper motor 118 to the connecting rod 110, a speed reduction effect is achieved while ensuring that the film-pulling rod 108 can reach the end of the stroke of the U-shaped guide rail 112. When it is necessary to remove the UV cutoff film 107, the microcontroller 5 only needs to control the dual-axis stepper motor 118 to reverse. Due to the elastic restoring force of the coil spring 116, the UV cutoff film 107 will gradually be wound onto the roller 117. Based on the above principle, the rapid and automatic covering and removing of the UV cutoff film 107 can be achieved, and the entire process can be completed in just a few seconds. When the covering-removal frequency of the ultraviolet cutoff membrane 107 is equal to the gas exchange rate of the photochemical reaction tube 104, rapid switching measurement of different wavelengths of the photochemical generation rate of reactive gases in the ambient atmosphere can be achieved. This allows for rapid verification of the influence of ultraviolet light on the photochemical generation rate of reactive gases in the ambient atmosphere. By extracting the full-band irradiation measurement data and the measurement data after deducting the ultraviolet band within a day, the present invention can obtain two sets of measurement data with different irradiation wavelengths within a day using only one photochemical reaction tube 104, which facilitates the analysis and understanding of the photochemical process in the ambient atmosphere.

[0068] (5) The atmospheric mixture containing active gases flowing out of the photochemical reaction device 1 is drawn into the precision optical cavity 11. During system operation, the pressure gauge 10 detects the pressure inside the precision optical cavity 11 in real time and adjusts the pumping speed of the air pump 8 in real time through the pumping mass flow meter 9 to maintain the pressure inside the precision optical cavity 11 at a stable value. The drive circuit board 17 controls the semiconductor light source 16 to emit divergent broadband light. The broadband light becomes parallel light after passing through the collimating lens 15, and then the stray light at the edge is filtered out by the aperture 14. After being deflected by 180° by the reflector 13 and the reflector 12, it enters the precision optical cavity 11. The two reflectors play a role in eliminating the misalignment problem between the semiconductor light source 16 and the precision optical cavity 11, and at the same time, they can reduce the overall axial dimension. Broadband light is reflected back and forth between two high-reflectivity mirrors 1101 within the precision optical cavity 11 and absorbed multiple times by the reactive gas in the atmospheric mixture. Since the number of reflections is as high as dozens, the angle of the two high-reflectivity mirrors 1101 needs to be precisely adjusted. By rotating the six-screw adjustment knob 1104, the two high-reflectivity mirrors 1101 can be deflected at a small angle, ultimately ensuring that the center of the broadband light after multiple reflections is coaxial with the precision optical cavity 11. In this design, the relatively large screw adjustment knob 1104 is located on the inner side of both ends of the gas flow optical cavity 1103, utilizing the spare volume on the inner side of both ends of the gas flow optical cavity 1103 to shorten the lateral length. The broadband light emitted from the precision optical cavity 11 is filtered by the filter 7 to remove excess wavelengths and then focused onto the photomultiplier tube 19 by the focusing lens 18. The photomultiplier tube 19 collects the transmitted light intensity after multiple reflections by the two high-reflectivity mirrors 1101 inside the high-precision cavity 11. This intensity is then transmitted via a microcontroller 5 to an industrial control computer 6, where it is fitted to obtain the ring-down time τ, based on the formula:

[0069]

[0070] The concentration of the active gas [C] can be calculated, where L is the ratio of the cavity length to the single absorption optical path length of the gas in the cavity, c is the speed of light, σ is the absorption cross section of the active gas to be tested, τ is the ringing time when the active gas to be tested is in the high-precision cavity 11, and τ0 is the background ringing time when there is no active gas to be tested in the high-precision cavity 11.

[0071] Record the photochemical reaction tube 104 in Figure 5 The length after the dashed line is l, and the gas flow velocity of the atmospheric mixture in the photochemical reaction tube 104 is v. The generation rate P of the reactive gas can then be calculated as: P = [C]·v / l. Since different gases have different absorption bands, different semiconductor light sources 16 of different bands can be used to measure the generation rate of different reactive gases.

[0072] The parts of this invention not described in detail are well-known to those skilled in the art. The embodiments described above are merely preferred embodiments of the invention, and do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Various modifications and improvements to the technical solutions of this invention made by those skilled in the art without departing from the spirit of the invention should fall within the protection scope defined by the claims of this invention.

Claims

1. A device for measuring the photochemical generation rate of reactive gases in the ambient atmosphere, characterized in that, The device includes: an air intake module, a photochemical reaction device (1), a broadband high-precision cavity measurement system, and a control system; The air intake module is used to inject pure ambient air or an air mixture with added reactive gas into the photochemical reaction device (1); The photochemical reaction device (1) is connected to the air intake module and is the site for photochemical reaction of atmospheric mixture. It can also automatically filter out ultraviolet light in the irradiation light. The broadband high-precision cavity measurement system is connected to the photochemical reaction device (1) and is used to measure the concentration of active gas generated by the photochemical reaction; The control system is used to monitor and control the working status of the air intake module, the photochemical reaction device (1) and the broadband high-precision cavity measurement system. At the same time, it calculates and processes the absorption photoelectric signal output by the broadband high-precision cavity measurement system to finally obtain real-time data on the photochemical generation rate of reactive gases in the ambient atmosphere. The photochemical reaction device (1) includes: a photochemical reaction tube (104) that allows the atmospheric mixture to diffuse uniformly and undergo photochemical reaction; an air inlet wall-penetrating connector (102) that connects the air inlet module to the photochemical reaction tube (104); an upper support (106) that presses the photochemical reaction tube (104) and supports the ultraviolet cutoff membrane (107); a lower support (105) that supports the photochemical reaction tube (104); a xenon lamp tube assembly (101) that provides artificial light; an automatic cover film system for automatically switching the irradiation light band; and a reaction device base (103). There are two upper supports (106) for the reaction tube, each in a semi-circular shape with five circular through holes around its perimeter; there are two lower supports (105) for the reaction tube, each in a square shape with the semi-circle removed, with a through hole at its lower right; the photochemical reaction tube (104) is installed between the two upper supports (106) and the two lower supports (105), and its front is connected to the air intake module via an air intake through-wall connector (102); the xenon lamp assembly (101) consists of a rectangular shell, multiple cylindrical xenon lamps, and four cylindrical support legs, with a reflective coating on the lower surface of the rectangular shell, and the axial direction of the cylindrical xenon lamps being aligned with the axial direction of the photochemical reaction tube (104); a U-shaped guide rail (112) is provided on the inner side of each end of the reaction device base (103). The device includes a central gear rotating shaft (111) and a right gear rotating shaft (114). The outer diameter of the U-shaped guide rail (112) is larger than the outer diameter of the upper support (106) of the reaction tube. The central gear rotating shaft (111) has a circular through hole for installing the air inlet wall connector (102). The upper part of the reaction device base (103) has four cylindrical holes. The photochemical reaction tube (104), the upper support (106) of the reaction tube, and the lower support (105) of the reaction tube are installed in the reaction device base (103). The xenon lamp tube assembly (101) is installed on the upper part of the photochemical reaction tube (104). The four cylindrical support legs of the xenon lamp tube assembly (101) are inserted into the four cylindrical holes of the reaction device base (103).

2. The device for measuring the photochemical generation rate of reactive gases in the ambient atmosphere according to claim 1, characterized in that, The air intake module includes: a three-way solenoid valve (2) for controlling whether the reaction gas is introduced, a filter membrane (3) for filtering out particulate matter in the ambient atmosphere, and an air intake flow meter (4) for controlling the flow rate of the reaction gas. The ambient air is injected into the photochemical reaction device (1) after passing through the filter membrane (3). The injection of the reaction gas and its mixing with the ambient air are controlled by the three-way solenoid valve (2) and the air inlet flow meter (4).

3. The device for measuring the photochemical generation rate of reactive gases in the ambient atmosphere according to claim 1, characterized in that, The photochemical reaction tube (104) includes: a steady-state flow tube (104-1) in which a photochemical reaction occurs; a first-stage split diffuser (104-2), a second-stage split diffuser (104-3), and a third-stage split diffuser (104-4) that uniformly diffuse the atmospheric mixture and generate a plug flow; a three-lobe connecting plate (104-7) for connecting and fixing the three split diffusers; an outlet cover plate (104-6) and an outlet pressure plate (104-5) for sealing the photochemical reaction tube (104). The steady-state flow tube (104-1) has a cubic cross-sectional shape at the front and a cylindrical shape at the middle and rear. It is made of quartz glass, with a black soluble polytetrafluoroethylene (PTFE) film coated on the front of its inner surface and a transparent soluble PTFE film coated on the rear. The front of the steady-state flow tube (104-1) contains three cubic cross-sectional diffusers: a first-stage diffuser (104-2), a second-stage diffuser (104-3), and a third-stage diffuser (104-4), from the outside to the inside. The diffusion angle of the front of the steady-state flow tube (104-1) and the three diffusers varies from the inside to the outside. The material of the three diverter diffusers is black polytetrafluoroethylene (PTFE). The three-bladed connecting plate (104-7) consists of three blades with an included angle of 120°, also made of black PTFE, which connect and fix the three diverter diffusers to the front of the steady-state flow tube (104-1). The tail of the steady-state flow tube (104-1) is sealed by an outlet cover plate (104-6) and an outlet pressure plate (104-5) made of black PTFE. A sealing ring is provided between the outlet cover plate (104-6) and the outlet pressure plate (104-5). The tail end of the outlet cover plate (104-6) is a hollow cylinder.

4. The device for measuring the photochemical generation rate of reactive gases in the ambient atmosphere according to claim 2, characterized in that, The automatic film covering system includes: a dual-axis stepper motor (118) that provides driving force, a drive gear (115) and a driven gear (113) that transmit driving force, an ultraviolet cutoff membrane (107) that can filter out the ultraviolet band of natural light or xenon lamp light, a film pulling rod (108) that pulls the ultraviolet cutoff membrane (107) to move, a U-shaped guide rail (112) that guides the film pulling rod (108) to move along a fixed trajectory, a connecting rod gear (110) and a telescopic sleeve rod (109) that cause the film pulling rod (108) to drive the ultraviolet cutoff membrane (107) to move along the trajectory of the U-shaped guide rail (112), a central gear rotating shaft (111) that mounts the connecting rod drive gear, a right gear rotating shaft (114) that mounts the driven gear (113), a roller (117) and a coil spring (116) for straightening the ultraviolet cutoff membrane (107), and a support rod (119) for supporting the shape of the ultraviolet cutoff membrane (107). The two output shafts of the dual-axis stepper motor (118) extend from the through holes opened at the lower right of the two reaction tube support brackets (105); there are two driving gears (115), which are respectively installed at both ends of the dual-axis stepper motor (118); there are two driven gears (113), which are respectively installed on the right gear rotating shafts (114) on both sides of the reaction device base (103); there are two connecting gears (110), which are respectively installed on the middle gear rotating shafts (111) on both sides of the reaction device base (103); the driven gears (113) mesh with the driving gears (115) and the connecting gears (110), the driving gears (115) and the driven gears (113) have the same number of teeth, and the connecting gears (110) have a greater number of teeth than the driving gears (115) and the driven gears (113); the connecting gears (110) consist of an incomplete gear with a circular through hole in the middle and a fixed The incomplete gear is composed of a telescopic cylinder; there are two telescopic sleeves (109), which are composed of a telescopic rod and a sleeve fixed at the end of the telescopic rod; the telescopic sleeve (109) is inserted into the telescopic cylinder of the connecting gear (110), the film pulling rod (108) is inserted into the sleeve at the end of the telescopic sleeve (109), one end of the ultraviolet cutoff membrane (107) is fixed to the film pulling rod (108), and the other end is fixed to the roller (117); two coil springs (116) fixed to the left side of the reaction device base (103) are respectively installed at both ends of the roller (117); a limit switch is provided at both ends of the U-shaped guide rail (112), and the two ends of the film pulling rod (108) are respectively inserted into the U-shaped guide rails on both sides of the reaction device base (103); there are five support rods (119), which are respectively installed in five circular through holes opened around the periphery of the support (106) on the reaction tube.

5. The device for measuring the photochemical generation rate of reactive gases in the ambient atmosphere according to claim 3, characterized in that, The broadband high-precision cavity measurement system includes: a semiconductor light source (16) that emits broadband light in the absorption band of the active gas to be measured; a driving circuit board (17) that powers and controls the temperature of the semiconductor light source (16); a collimating lens (15) that converts the divergent light emitted by the semiconductor light source (16) into parallel light; an aperture (14) that filters out stray light at the edge of the parallel light; a first reflector (13) and a second reflector (12) that deflect the light path by 180°; and a precision optical cavity (11) that causes multiple reflections of the broadband light. ), a filter (7) for filtering out broadband light and excess wavelength light in ambient light, a focusing lens (18) for focusing broadband light emitted from the precision optical cavity (11), a photomultiplier tube (19) for photoelectric conversion of the focused broadband light, a pressure gauge (10) for real-time monitoring of the internal pressure of the precision optical cavity (11), a gas pump (8) for pumping gas from the photochemical reaction device (1) into the precision optical cavity (11), and a pumping flow meter (9) for controlling the pumping speed of the gas pump (8); Following the semiconductor light source (16) in the broadband light propagation direction are: collimating lens (15), aperture (14), first reflector (13), second reflector (12), precision optical cavity (11), filter (7), focusing lens (18) and photomultiplier tube (19). The filter (7) is a narrowband filter. The focusing lens (18) and the filter (7) are provided with light shielding tubes on their outer sides.

6. The device for measuring the photochemical generation rate of reactive gases in the ambient atmosphere according to claim 5, characterized in that, The precision optical cavity (11) includes: a high-reflection mirror (1101) that causes broadband light to reflect back and forth multiple times, a high-reflection mirror pressure plate (1102) for pressing the high-reflection mirror (1101), a gas flow optical cavity (1103) that allows the gas to be irradiated by broadband light, and a threaded adjustment knob (1104) for adjusting the angle of the high-reflection mirror (1101). The gas flow optical cavity (1103) is a hollow cylindrical cavity that is thick at both ends and thin in the middle. The upper left and upper right parts are respectively provided with a pipe that is perpendicular to it, namely an air inlet pipe and an air outlet pipe. The air inlet pipe is connected to the hollow cylinder at the tail end of the air outlet cover plate (104-6). The air outlet pipe is connected to the pressure gauge (10) and the air pump flow meter (9) connected to the air pump (8) through a tee. Three small through holes with equal arc length are opened on the inner side of both ends of the gas flow optical cavity (1103). There are two high-reflectivity mirrors (1101), which are symmetrically installed inside the gas flow optical cavity (1103) on both sides, with their high-reflectivity mirror surfaces facing each other. A highly elastic sealing ring is provided between the high-reflectivity mirror (1101) and the gas flow optical cavity (1103) to seal both ends of the gas flow optical cavity (1103) and to provide elastic restoring force to the high-reflectivity mirror (1101). The high-reflectivity mirror pressure plate (1102) is disc-shaped with a through hole in its center. The diameter of the through hole is smaller than that of the high-reflectivity mirror (1101). The outer diameter of the high-reflectivity mirror pressure plate (1101) is as follows: The high-reflectivity mirror pressure plate (1102) has three threaded holes of equal arc length around its circumference. There are two high-reflectivity mirror pressure plates (1102), symmetrically installed on both sides of the gas flow optical cavity (1103). A cylindrical groove is formed on the inner side of the high-reflectivity mirror pressure plate (1102) to hold the high-reflectivity mirror (1101). The outer diameter of the high-reflectivity mirror pressure plate (1102) is equal to the outer diameter of both ends of the gas flow optical cavity (1103). The outer periphery of the high-reflectivity mirror pressure plate (1102) is... A cylindrical step is provided, the diameter of which is smaller than the inner diameter of both ends of the gas flow optical cavity (1103). The cylindrical step extends into the interior of both ends of the gas flow optical cavity (1103) by about 5 mm. There are six threaded adjustment knobs (1104), which are located on the inner side of both ends of the gas flow optical cavity (1103). They pass through three small through holes on the inner side of both ends of the gas flow optical cavity (1103) and are screwed onto the three threaded holes opened around the periphery of the high-reflection mirror pressure plate (1102).

7. The device for measuring the photochemical generation rate of reactive gases in the ambient atmosphere according to claim 4, characterized in that, The control system includes an industrial computer (6) and a microcontroller (5); The industrial control computer (6) directly receives the signal from the pressure gauge (10). The industrial control computer (6) directly controls the air intake flow meter (4), the air extraction flow meter (9), and the drive circuit board (17). The industrial control computer (6) indirectly controls the switch of the air pump (8) through the microcontroller (5). The microcontroller (5) receives the signal from the limit switches installed at both ends of the U-shaped guide rail (112) and controls the forward and reverse rotation of the dual-axis stepper motor (118). The microcontroller (5) controls the opening and closing of the three-way solenoid valve (2). The microcontroller (5) receives the signal from the pressure gauge (10) and the photomultiplier tube (19) and uploads it to the industrial control computer (6).

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