A photoionization sensor for differentiating gas types

Abstract

The present application discloses a photoionization sensor for differentiating gas types, which is used to improve the classification ability of the photoionization sensor when detecting gases with different ionization energies. The present application includes: an ultraviolet lamp module, a sensor body, an ion current receiving electrode pair, an amplifier circuit, and an output module; a gas flow area and an information processing area are provided on the sensor body; at least two ultraviolet light windows are provided on the ultraviolet lamp module, and the ultraviolet light spectral components emitted by each of the ultraviolet light windows are different. The ultraviolet lamp module is arranged in the gas flow area, and the ultraviolet light windows are used to emit ultraviolet light after the ultraviolet lamp module generates an ultraviolet light source; at least two ion current receiving electrode pairs are installed in the gas flow area; at least two amplifier circuits are installed in the information processing area, and the ion current receiving electrode pair is connected to the amplifier circuit; the output module is arranged in the information processing area, and the output module is connected to the amplifier circuit.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of detection, and in particular to a photoionization sensor for distinguishing gas types. Background Art

[0002] The photoionization sensor is an important sensor for detecting gaseous substances at present. Its working principle is as follows: The gas to be detected absorbs photons emitted by an ultraviolet lamp and is ionized into positive ions and electrons. For a gas molecule to be successfully ionized, the energy of the ultraviolet light photon (calculated according to E = hν) needs to be greater than the ionization energy of the gas molecule. Under the action of an external electrode, the ions move in space to form a weak current, which is collected. This weak current is the photoionization current. The generated ionization current is generally converted into a voltage value convenient for measurement through an amplifier circuit with a large resistance of the order of 10 9 Ω, and finally, through a logic analysis and calculation by an output module, data on whether the gas to be detected is ionized is obtained.

[0003] However, during the gas detection process, the gas to be detected may not be a single gas, but can be a mixture of multiple gases. During the detection process, since there is only one ultraviolet light source and one ultraviolet light window in the ultraviolet lamp module of the traditional photoionization sensor, and there is only one amplifier circuit and one output module on the photoionization sensor, the ionization energy of the ultraviolet light emitted from each ultraviolet light window is fixed, and only the gas to be detected with an ionization energy less than the ultraviolet light ionization energy can be ionized, while the gas to be detected with an ionization energy greater than the ultraviolet light ionization energy cannot be ionized. That is, only the analysis data indicating the presence of a gas type with an ionization energy less than this ultraviolet light ionization energy in the gas to be detected can be obtained, and further analysis of the gas types in the gas to be detected cannot be continued to obtain more analysis data on the gas types.

[0004] Currently, by adding another ultraviolet lamp module capable of emitting ultraviolet light with different energies and adding a new amplifier circuit, the photoionization sensor can continue to perform further analysis on the gas types of the gas to be detected and obtain more analysis data on the gas types.

[0005] However, in the method of adding an ultraviolet lamp module, the gas to be detected is respectively affected by the two ultraviolet lamp modules, that is, the gas to be detected does not share the same ultraviolet light source. There are uncontrollable differences in various aspects such as the gas concentration and purity of these ultraviolet light sources, and the attenuation rate of the light intensity may also be different during long-term use. During the use process, the accuracy of the analysis data for different gas types will be reduced, resulting in a decrease in the classification ability of the traditional photoionization sensor when detecting gases with different ionization energies. Summary of the Invention

[0006] An embodiment of the present application provides a photoionization sensor for distinguishing gas types, which is characterized by including:

[0007] An ultraviolet lamp module, a sensor main body, an ion current receiving electrode pair, an amplifying circuit, and an output module;

[0008] A gas flow area and an information processing area are provided on the sensor main body;

[0009] At least two ultraviolet light windows are provided on the ultraviolet lamp module, and the ultraviolet light spectral components emitted by each ultraviolet light window are different. The ultraviolet lamp module is arranged in the gas flow area, and the ultraviolet light window is used to emit ultraviolet light after the ultraviolet lamp module generates an ultraviolet light source;

[0010] At least two of the ion current receiving electrode pairs are installed in the gas flow area. The ion current receiving electrode pair is placed in front of the ultraviolet light window, and the ion current receiving electrode pair is used to receive the signal generated when the gas to be measured is ionized;

[0011] At least two of the amplifying circuits are installed in the information processing area. The ion current receiving electrode pair is connected to the amplifying circuit, and the amplifying circuit is used to process the signal collected by the ion current receiving electrode pair;

[0012] The output module is arranged in the information processing area. The output module is connected to the amplifying circuit, and the output module is used to receive and generate analysis data for distinguishing the gas to be measured based on the ionization energy threshold according to the signal processed by the amplifying circuit.

[0013] Optionally, the ultraviolet lamp module includes an AC voltage module, an ultraviolet light window, an ultraviolet excitation electrode pair, an ultraviolet lamp body, and a working gas;

[0014] The ultraviolet lamp body contains the working gas and emits ultraviolet light under the excitation of the ultraviolet excitation electrode pair;

[0015] At least two ultraviolet light windows are provided on the ultraviolet lamp body. After the emitted ultraviolet light generated by the working substance passes through the ultraviolet light window, the spectral components emitted by each ultraviolet light window are different;

[0016] The ultraviolet excitation electrode pair is installed on the ultraviolet lamp body, and the ultraviolet excitation electrode pair is used to excite the working gas to generate an ultraviolet light source;

[0017] The AC voltage module is connected to the ultraviolet excitation electrode pair, and the AC voltage module is used to provide a high-voltage AC voltage to the ultraviolet excitation electrode pair.

[0018] Optionally, the AC voltage module includes a high-voltage power supply module and a high-voltage power conversion module;

[0019] The high-voltage power supply module is connected to the high-voltage power conversion module;

[0020] The high-voltage power conversion module is connected to the ultraviolet excitation electrode pair, and the high-voltage power conversion module is used to supply electrical energy to the ultraviolet excitation electrode pair.

[0021] Optionally, the ultraviolet lamp module further includes a gas adsorbent;

[0022] The gas adsorbent is contained in the ultraviolet lamp module, and the gas adsorbent is used to adsorb impurity gases in the ultraviolet lamp module.

[0023] Optionally, the gas flow region includes an air inlet, an exhaust port, and an ionization region;

[0024] The air inlet is provided on the sensor body, and the gas to be measured enters the ionization region through the air inlet, and the gas to be measured is ionized in the ionization region;

[0025] The exhaust port is provided on the sensor body, and the exhaust port is used to evacuate the gas to be measured from the ionization region.

[0026] Optionally, the gas flow region further includes an air pump for pumping the gas to be measured into the ionization region.

[0027] Optionally, the gas flow region further includes an exhaust pump for discharging the gas to be measured from the ionization region.

[0028] Optionally, the ion current receiving electrode pair is placed parallel to the ultraviolet light window.

[0029] Optionally, the ion current receiving electrode pair is placed perpendicular to the ultraviolet light window.

[0030] Optionally, the output module includes a logic judgment module and an information output module;

[0031] The logic judgment module is connected to the amplifier circuit, and the logic judgment module is used to analyze the signal processed by the amplifier circuit;

[0032] There is a connection between the logic judgment module and the information output module, and the information output module is used to generate analysis data indicating the gas type of the gas to be measured.

[0033] From the above technical solutions, it can be seen that the embodiments of the present application have the following advantages:

[0034] Multiple ultraviolet light windows are simultaneously provided on the same ultraviolet lamp module. Each ultraviolet light window ionizes the gas to be measured by emitting ultraviolet light. Signals generated during the ionization of the gas to be measured are received by multiple ion current receiving electrode pairs. The ion current receiving electrode pairs transmit the signals to an amplification circuit for information processing. The output module receives the information transmitted by multiple amplification circuits for logical analysis and calculation to determine whether the gas to be measured is ionized on the ultraviolet light window, thereby increasing the gas type analysis data. Since the materials used for the ultraviolet light windows are different, the spectral components of the ultraviolet light emitted by the ultraviolet light windows are also different, resulting in differences in the data received by the amplification circuit. The output module will perform logical analysis and calculation on the differences between these data to obtain analysis data for distinguishing the gas to be measured based on the ionization energy threshold. In the embodiment of the present application, multiple ultraviolet light windows with different materials are provided on the same ultraviolet lamp module to share a single ultraviolet light source. The ultraviolet light source, gas concentration, purity, etc. of each ultraviolet light window are almost the same, improving the classification ability of the photoionization sensor when detecting gases with different ionization energies. Description of the Drawings

[0035] Figure 1 Schematic structural diagram of an embodiment of a photoionization sensor for distinguishing gas types;

[0036] Figure 2 Schematic structural diagram of an embodiment of an ultraviolet lamp module;

[0037] Figure 3 Schematic structural diagram of an embodiment of an ultraviolet lamp module;

[0038] Figure 4 Schematic structural diagram of another embodiment of an ultraviolet lamp module;

[0039] Figure 5 Schematic structural diagram of another embodiment of a photoionization sensor for distinguishing gas types;

[0040] Figure 6 Schematic structural diagram of an embodiment of the positional relationship between an ultraviolet lamp and an ion current receiving electrode pair;

[0041] Figure 7 Schematic structural diagram of another embodiment of the positional relationship between an ultraviolet lamp and an ion current receiving electrode pair;

[0042] Figure 8 Response graph of a photoionization sensor with double ultraviolet light windows when measuring IBE gas;

[0043] Figure 9 Response graph of a photoionization sensor with double ultraviolet light windows when measuring ammonia gas;

[0044] Figure 10Response graph of a photoionization sensor with a double-ultraviolet lamp window when measuring a mixture of ammonia and IBE. Detailed implementation mode

[0045] The technical solutions in the present application will be clearly and completely described below in conjunction with the accompanying drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0046] The embodiment of the present application discloses a photoionization sensor for distinguishing gas types, which is used to improve the classification ability of the photoionization sensor when detecting gases with different ionization energies.

[0047] Please refer to Figure 1 , the embodiment of the present application provides a photoionization sensor for distinguishing gas types, including:

[0048] An ultraviolet lamp module 1, a sensor body 2, an ion current receiving electrode pair 3, an amplification circuit 4 and an output module 5;

[0049] A gas flow area and an information processing area are provided on the sensor body 2;

[0050] At least two ultraviolet light windows are provided on the ultraviolet lamp module 1, and the ultraviolet light spectral components emitted by each ultraviolet light window are different. The ultraviolet lamp module 1 is arranged in the gas flow area, and the ultraviolet light window is used to emit ultraviolet light after the ultraviolet lamp module generates an ultraviolet light source;

[0051] At least two of the ion current receiving electrode pairs 3 are installed in the gas flow area, and the ion current receiving electrode pair 3 is placed in front of the ultraviolet light window. The ion current receiving electrode pair 3 is used to receive the signal generated when the gas to be measured is ionized;

[0052] At least two of the amplification circuits 4 are installed in the information processing area. The ion current receiving electrode pair 3 is connected to the amplification circuit 4, and the amplification circuit 4 is used to process the signal collected by the ion current receiving electrode pair 3;

[0053] The output module 5 is arranged in the information processing area. The output module 5 is connected to the amplification circuit 4, and the output module 5 is used to receive and generate analysis data for distinguishing the gas to be measured based on the ionization energy threshold according to the signal processed by the amplification circuit 4.

[0054] Figure 1Taking the photoionization sensor with two ultraviolet light windows as an example, the structure of the photoionization sensor with two ultraviolet light windows and the functions of its structure will be described first below.

[0055] The photoionization sensor with two ultraviolet light windows has a sensor body 2. The sensor body 2 is a sensor housing, which is used to install other detection components and provide a detection space for the gas to be measured. The sensor body 2 can be divided into two areas: a gas flow area and an information processing area. The devices in the gas flow area include an ultraviolet lamp module 1 and an ion current receiving electrode pair 3, and the devices in the information processing area include an amplifier circuit 4 and an output module 5.

[0056] In practical applications, the gas to be measured needs to be introduced into the gas flow area, and the gas to be measured is ionized by the ultraviolet lamp module 1. The information processing area is used to process and output the information data detected in the gas flow area.

[0057] The ultraviolet lamp module 1 is a device that emits ultraviolet light. On the photoionization sensor with two ultraviolet light windows, the ultraviolet lamp module 1 is provided with two ultraviolet light windows 7. The materials of these two ultraviolet light windows are different, and the wavelengths and energies of the ultraviolet light that can pass through are also different, resulting in different ultraviolet spectral components of the emitted light. Since the ultraviolet lamp module 1 only generates one ultraviolet light source, these two ultraviolet light windows 7 share the same ultraviolet light source. Sharing the same ultraviolet light source by the two ultraviolet light windows 7 can reduce the differences in ultraviolet light sources, gas concentrations, purities, etc. Compared with the photoionization sensor using multiple ultraviolet lamp modules, the photoionization sensor with two ultraviolet light windows uses only one ultraviolet light source, and the data collected has smaller errors.

[0058] The ion current receiving electrode pair 3 is composed of two electrode plates. In the photoionization sensor with two ultraviolet light windows, two sets of ion current receiving electrode pairs 3 are provided to collect the gas ions ionized by the two ultraviolet light windows 7 respectively, and then form a weak current signal. The ion current receiving electrode pair 3 will transmit the collected weak current signal to the amplifier circuit 4.

[0059] In the photoionization sensor with two ultraviolet light windows, two amplifier circuits 4 are provided. The two amplifier circuits 4 are respectively connected to the two ion current receiving electrode pairs 3. The two amplifier circuits 4 are used to respectively receive the weak current signals formed by the two ion current receiving electrode pairs 3, and amplify the weak current signals into an analog output of a low-resistance voltage signal. This analog output is finally transmitted by the amplifier circuit 4 to the output circuit 5.

[0060] In a photoionization sensor with a dual-ultraviolet light window, an output module 5 is provided. The output module 5 is used to receive the analog outputs transmitted by two amplification circuits 4, perform logical analysis and calculation, and generate analysis data for distinguishing the gas to be measured based on the ionization energy threshold.

[0061] The method for the ultraviolet lamp module to generate ultraviolet light is achieved by exciting rare gases to produce plasma emission, and its emission spectrum contains ultraviolet spectra of specific wavelengths. The plasma emission wavelength of a specific atom depends on its internal shell electron structure. Although there are many emission wavelengths, each emission wavelength is basically a fixed value and is difficult to change after selecting the encapsulated working substance. Another method is to use materials with different transmittances for ultraviolet light of different wavelengths to make the ultraviolet light window 7, so as to achieve the selection of ultraviolet wavelengths. For example: for the common working substance Kr gas, the stronger ultraviolet wavelengths in its spectral lines are 116.5nm and 123.6nm, corresponding to photon energies of 10.6eV and 10.0eV. Therefore, by using appropriate ultraviolet window materials, the above wavelengths can be selected not to pass through, or one or both can pass through.

[0062] In this embodiment, according to the above method for generating the ultraviolet light source, two ultraviolet light windows 7 made of different materials are installed on the same ultraviolet lamp module, so that the two ultraviolet light windows 7 have different transmittances for ultraviolet light of different wavelengths, resulting in differences in the gases that can be ionized by the two ultraviolet light windows 7, and realizing the detection of different gas types.

[0063] Without increasing the ultraviolet lamp module, the ultraviolet lamp window can obtain ultraviolet light that can transmit different energies, and the ultraviolet light sources, gas concentrations, purities, etc. of each ultraviolet light window are almost the same, which not only realizes the detection of different gas types, but also improves the classification ability of the photoionization sensor when detecting gases with different ionization energies.

[0064] Secondly, during the detection process, there is no need to consider many initial matching problems, calibration problems, and additional maintenance problems when multiple are used in combination. Since this embodiment uses the same ultraviolet lamp module and there is only one ultraviolet light source, the cost and the volume of the photoionization sensor are reduced.

[0065] Please refer to Figure 2 , this application embodiment provides one kind, including:

[0066] Optionally, the ultraviolet lamp module 1 includes an AC voltage module 6, an ultraviolet light window 7, an ultraviolet excitation electrode pair 8, an ultraviolet lamp body 9, and a working gas 10;

[0067] At least two ultraviolet light windows are provided on the ultraviolet lamp body 9, and the ultraviolet light spectral components emitted by each ultraviolet light window 7 are different;

[0068] The ultraviolet lamp body 9 contains the working gas and emits ultraviolet light under the excitation of the ultraviolet excitation electrode pair 8;

[0069] The ultraviolet excitation electrode pair 8 is installed on the ultraviolet lamp body 9, and the ultraviolet excitation electrode pair 8 is used to excite the working gas 10 to generate an ultraviolet light source;

[0070] The AC voltage module 6 is connected to the ultraviolet excitation electrode pair 8, and the AC voltage module 6 is used to provide a high-voltage AC voltage to the ultraviolet excitation electrode pair 8.

[0071] In this embodiment, taking the ultraviolet lamp module with double ultraviolet light windows as an example, the structure of the ultraviolet lamp module 1 will be described.

[0072] The ultraviolet lamp body 9 is the framework of the ultraviolet lamp module 1. In this embodiment, the ultraviolet lamp body 9 of the ultraviolet lamp module with double ultraviolet light windows is cylindrical. There are two ultraviolet lamp mounting ports on the ultraviolet lamp body 9, and the ultraviolet lamp mounting ports are used to mount the ultraviolet light window 7.

[0073] In this embodiment, the production material of the ultraviolet light window 7 can be MgF 2 , CaF 2 , LiF, etc., which are not limited here. However, the materials of the multiple ultraviolet light windows 7 on the same ultraviolet lamp module 1 are different from each other, so that the ultraviolet light windows 7 emit ultraviolet light with different energies.

[0074] An ultraviolet light source needs to be introduced into the ultraviolet lamp body 9. In the embodiment of the present application, the working gas 10 is injected into the ultraviolet lamp body 9. The working gas 10 is a gaseous substance that can be excited under certain conditions to generate an ultraviolet light source. The working gas used in this embodiment is the noble gas Kr. In theory, there are other noble gases that can be used as the working gas, which are not limited here. Since the plasma state of the working gas 10 is easily quenched by other impurity gases, the ultraviolet lamp module 1 is made into a low-pressure sealed state.

[0075] The ultraviolet excitation electrode pair 8 is also provided on the ultraviolet lamp module with double ultraviolet light windows. Each ultraviolet excitation electrode pair 8 has two electrodes. The ultraviolet excitation electrode pair 8 is used to excite the working gas 10 so that the working gas 10 is excited to generate an ultraviolet light source. The ultraviolet excitation electrode pair 8 is connected to the AC voltage module 6, and the AC voltage module 6 connects a high-voltage AC voltage to the ultraviolet excitation electrode pair 8 to generate an alternating electric field environment. Under such an electric field environment, the working gas 10 will be excited to generate an ultraviolet light source, and the ultraviolet light source is emitted through the two ultraviolet light windows 7.

[0076] In this embodiment, the material of the ultraviolet excitation electrode pair 8 can be a metal such as Cu or Au or other materials with a conductive coating, which are not limited here.

[0077] In the embodiment of the present application, taking the ultraviolet lamp module with double ultraviolet light windows as an example, the manufacturing process of the ultraviolet lamp module 1 will be described.

[0078] In the ultraviolet lamp module with double ultraviolet light windows, the ultraviolet lamp body 9 is a cylindrical glass tube. One ultraviolet lamp mounting port of the cylindrical glass tube is first bonded to the ultraviolet light window 7 with substances such as low-temperature glass powder at high temperature to achieve a semi-open and semi-closed structure. The material of the ultraviolet light window 7 here is magnesium fluoride. Subsequently, substances such as low-temperature glass powder are added to the other ultraviolet lamp mounting port of the cylindrical glass tube, and the above device is sealed in a low-pressure environment filled with working gas 10. The working gas 10 here is Kr gas, and the pressure is about 300 Pa. Then it is heated to the working temperature of the low-temperature glass powder and pasted to achieve the sealing of the working gas 10 and the bonding of the ultraviolet light window. Then it is cooled and connected to the atmosphere. After installing the ultraviolet excitation electrode pair 8, the manufacturing of the ultraviolet lamp module 1 with a vacuum and double windows is completed.

[0079] Please refer to Figure 3 and Figure 4 , it should be noted that in addition to the photoionization sensor with double ultraviolet light windows, theoretically, the manufacturing of photoionization sensors with more ultraviolet light windows can also be achieved. Figure 3 is the structural diagram of the ultraviolet lamp module with triple ultraviolet light windows. Figure 4 is the structural diagram of the ultraviolet lamp module with quadruple ultraviolet light windows. Theoretically, by manufacturing the ultraviolet lamp module with multiple ultraviolet light windows, the corresponding photoionization sensor can be made, and the detection fineness of the photoionization sensor when increasing the analysis data of gas types can be improved.

[0080] Please refer to Figure 5 , the structure of the photoionization sensor will be described in detail below:

[0081] Optionally, the AC voltage module 6 includes a high-voltage power supply module 11 and a high-voltage power supply conversion module 12;

[0082] The high-voltage power supply module 11 is connected to the high-voltage power supply conversion module 12;

[0083] The high-voltage power supply conversion module 12 is connected to the ultraviolet excitation electrode pair 8, and the high-voltage power supply conversion module 12 is used to supply electrical energy to the ultraviolet excitation electrode pair 8.

[0084] In this embodiment, the AC voltage module 6 is divided into two parts. One is the high-voltage power supply module 11, which provides high-voltage electrical energy during operation. The other is the high-voltage power supply conversion module 12, which converts the high-voltage power supplied by the high-voltage power supply module 11 into a high-voltage AC voltage, so that the ultraviolet excitation electrode pair 8 obtains the high-voltage AC voltage.

[0085] Optionally, the ultraviolet lamp module 1 further includes a gas adsorbent;

[0086] The gas adsorbent is included in the ultraviolet lamp module, and the gas adsorbent is used to adsorb impurity gases in the ultraviolet lamp module.

[0087] In this embodiment, the gas adsorbent may be an alloy material of Zr, Al, and V, which is not limited herein. During the manufacturing process or use of the ultraviolet lamp module 1, impurity gases may penetrate into the working gas, and the gas adsorbent will adsorb the impurity gases inside the ultraviolet lamp module 1.

[0088] Optionally, the gas flow region includes an air inlet 13, an exhaust port 14, and an ionization region 15;

[0089] The air inlet 13 is provided on the sensor body 1, and the gas to be measured enters the ionization region through the air inlet 13, and the gas to be measured is ionized in the ionization region 15;

[0090] The exhaust port 14 is provided on the sensor body 1, and the exhaust port 14 is used to extract the gas to be measured from the ionization region 15.

[0091] An air inlet 13 and an exhaust port 14 are provided in the gas flow region, and the gas to be detected is introduced into the ionization region 15 through the air inlet 13 and the exhaust port 14. Among them, the method of introducing the gas to be detected into the ionization region 15 is mainly two types: the active pump suction method or the passive diffusion method. The passive diffusion method is to change the concentration gradient difference on both sides of the air inlet 13, so that the gas to be detected spreads to the ionization region 15 through the air inlet 13. When the detection is completed, by changing the concentration gradient difference on both sides of the exhaust port 14, the gas to be detected spreads from the ionization region 15 to the outside through the exhaust port 14. The active pump suction method is to install an air pump on the exhaust port 14 or the air inlet 13, and the gas to be detected is introduced into the ionization region 15 and discharged from the ionization region 15 through the air pump. For the diffusion detection or pump suction detection, the flow rate is 50 - 1000 mL / min, preferably in the range of 100 - 400 mL / min.

[0092] The following is an explanation of the active pump suction method:

[0093] Optionally, the gas flow region further includes a suction pump 16 for pumping the gas to be measured into the ionization region 15.

[0094] Optionally, the gas flow region further includes an exhaust pump 17 for discharging the gas to be measured from the ionization region 15.

[0095] In this embodiment, the air pump can be divided into an air extraction pump 16 and an air exhaust pump 17 according to the installation position. The air extraction pump 16 is used to pump the gas to be measured into the ionization region 15, and the air exhaust pump 17 is used to discharge the gas to be measured from the ionization region 15. On the same photoionization sensor, only one of the air extraction pump 16 and the air exhaust pump 17 needs to be set to achieve the purpose of the active pumping method, or the air extraction pump 16 and the air exhaust pump 17 can be installed at the same time, which is not limited here.

[0096] Optionally, the output module 5 includes a logic judgment module 18 and an information output module 19;

[0097] The logic judgment module 18 is connected to the amplifier circuit 4, and the logic judgment module 18 is used to analyze the signal processed by the amplifier circuit 4;

[0098] The logic judgment module 18 is connected to the information output module 19, and the information output module 19 is used to generate gas type analysis data indicating the gas to be measured.

[0099] In this embodiment, the logic judgment module 18 and the information output module 19 are mainly used to perform logical judgment on the electrical signals sent by the amplifier circuit 4.

[0100] Please refer to Figure 6 and Figure 7 , and the placement positions of the ion current receiving electrode pair 3 and the ultraviolet light window 7 will be described below:

[0101] Optionally, the ion current receiving electrode pair 3 is placed parallel to the ultraviolet light window 7.

[0102] Optionally, the ion current receiving electrode pair 3 is placed perpendicular to the ultraviolet light window 7.

[0103] Currently, in the photoionization sensor, the ion current receiving electrode pair 3 and the ultraviolet light window 7 have different position installation methods. Figure 6 shows the design where the positive and negative electrodes are parallel to the ultraviolet light emission direction, Figure 7 shows the design where the positive and negative electrodes are perpendicular to the ultraviolet light emission direction. When adopting Figure 7 's design method, there should be a light passing hole on the electrode close to the ultraviolet light window 7 so that the ultraviolet light passes through the electrode to reach between the two electrodes. In Figure 6 and Figure 7 , the ultraviolet light source is sent through the ultraviolet light window 7, and the emitted ultraviolet light direction is parallel upward. The ultraviolet light source of the common photoionization sensor is realized by the plasma luminescence of rare gases, and these ultraviolet lights are emitted through the transparent layer of the ultraviolet light source. The light source of the common photoionization sensor is cylindrical at the ultraviolet transparent layer end. The use of the external light source is to ionize the gas molecules to be measured between the ionization regions 15. InFigure 6 and Figure 7 In Figure 7 , the ion current receiving electrode pair 3 has a positive and a negative electrode, which are used to generate an electric field to collect the ionized gas molecule ions to be measured. In Figure 6 In Figure 6 , the gas flow direction in the ionization region 15 can be perpendicular to the paper surface, and can enter the ionization region 15 through the micropores on the ion current receiving electrode pair 3, perpendicular to the positive and negative electrodes of the ion current receiving electrode pair 3, or flow from top to bottom or from bottom to top parallel to the ultraviolet light direction. Figure 7 In Figure 7 , the ionization region 15 can flow perpendicular to the paper surface or within the paper surface parallel to the positive and negative electrodes of the ion current receiving electrode pair 3, or flow parallel to the ultraviolet light direction perpendicular to the positive and negative electrode plates of the ion current receiving electrode pair 3.

[0104] In this embodiment, when it is measured that there is a gas to be measured whose ionization energy is less than the energy of the ultraviolet light emitted from a certain ultraviolet light window 7, the gas concentration of this type of gas to be measured can also be calculated. The implementation steps are described below:

[0105] When the high-voltage power supply module 11 inputs a voltage V to the high-voltage power supply conversion module 12, an alternating current signal is generated by the oscillation circuit in the high-voltage power supply conversion module 12, and this signal is amplified hundreds of times by the boost circuit in the high-voltage power supply conversion module 12. This high-frequency alternating voltage can excite the ultraviolet lamp module 1 filled with rare gas to emit ultraviolet light of a certain intensity. The ultraviolet light passes through the ultraviolet light windows 7 made of different materials, and emits ultraviolet light of different energies. The ultraviolet light of different energies ionizes some nearby organic and inorganic gas molecules, generating ions. These ions are collected by the positive and negative electrode plates of the ion current receiving electrode pair 3 near the light source, generating a weak current. This current is amplified by the amplifier circuit 4, and finally an analog output of a low-resistance voltage signal is generated. The output module 5 analyzes, calculates and outputs the analog output of this low-resistance voltage signal, thereby completing the detection of gas molecules. The gas molecule ions generated by ultraviolet light excitation are approximately proportional to the concentration of gas molecules. Because when the gas type is known, the concentration of gas molecules can be determined. From the above steps, it can be seen that in addition to detecting the type of gas in the gas to be measured, this photoionization sensor can also calculate the concentration of the gas to be measured to a certain extent.

[0106] The following will describe the specific usage steps of the photoionization sensor in detail. For the purpose of example, a photoionization sensor with a double ultraviolet light window is used as an example.

[0107] Please refer to Figures 8 to 10 , when using the photoionization sensor with a double ultraviolet light window, the ultraviolet light windows made of CaF 2 material and MgF 2 are used respectively. CaF 2The ultraviolet light window of the material and MgF 2 both generate an output voltage, corresponding to V c and V m respectively. Due to the different spectral components of the ultraviolet light on both sides (different wavelengths and intensities, and even for the same wavelength, the transmittance of the ultraviolet light is also different). Photoionization sensors generally use isobutene (IBE) to calibrate the relationship between its output voltage and gas concentration. For other gases, the calibration factor (CF) value is used for conversion. For the same gas, the CF value is different when it is excited at different ultraviolet light wavelengths. The specific conversion method is as follows:

[0108] C 被测气体 = CF 被测气体 × C IBE等效浓度 Formula 1

[0109] For a certain gas to be detected, the IBE equivalent concentration on the CaF 2 window side, that is, the IBE equivalent gas concentration (C c ) with an ionization energy (IP) not exceeding 10.0 eV and the output voltage (V c ) has the following calibration relationship:

[0110] C c = f c (V c ) Formula 2

[0111] For a certain gas to be detected, the IBE equivalent concentration on the MgF 2 window side, that is, the IBE equivalent gas concentration (C m ) with an IP not exceeding 10.6 eV and the calibration of the output voltage (V m ) has the following relationship:

[0112] C m = f m (V m ) Formula 3

[0113] If there are multiple gases in the gas to be detected, then on the CaF 2 side, the CF of the gas with an IP greater than 10.0 eV is 0, and the relationship between the concentration of the gas with an IP less than or equal to 10.0 eV and C c in Formula 2 is as follows:

[0114]

[0115] Similarly, on the MgF 2 side, the relationship between the concentration of each gas with an IP not greater than 10.6 eV and C m is as follows:

[0116]

[0117] When V c and V m When the maximum output voltage is not exceeded, the concentration of substances with IP not higher than 10.0eV is calculated as Vc using Formula 2:

[0118] If the detected gas is known to be one type, the CF value CF can be used c1 C c Correction calculation of the concentration of the substance being measured (C Target ), the specific formula is:

[0119] C Target =C c ·CF c1 Formula 6

[0120] Combining Formula 2 and Formula 7, the calculation formula for the gas concentration with IP not higher than 10.0eV is:

[0121] C Target =F c (V c )·CF c1 Formula 7

[0122] The concentration of substances with IP between 10.0 and 10.6 eV is expressed as V c With V m Calculate together, when the gas with IP higher than 10.0eV but not higher than 10.6eV is one and the concentration of the gas with IP not higher than 10.0eV is also one, according to the above formula, the calculation formula is:

[0123] C Target =(F m (V m )-F c (V c )·CF c1 / CF m1 )·CF m2 Formula 8

[0124] Since MgF 2 The side contains 10.0eV and 10.6eV of ultraviolet light, so V m The value should be greater than or equal to V c When the voltage output value on one side is saturated, it should be V m Saturation value V c The value is not saturated. At this time, the concentration of substances with IP not higher than 10.0eV is still V c Calculation, while MgF 2 The side saturation indicates that the concentration of IP in the range of 10.0 to 10.6 eV exceeds that of MgF 2 The maximum detectable equivalent IBE concentration and the corresponding CaF2 Measure the difference of the gas after conversion. When the output values of both bilateral voltages are saturated, it indicates that the concentration of substances with IP not higher than 10.0 eV exceeds CaF 2 The maximum detectable equivalent IBE concentration on one side, and at this time, the concentration of substances with IP in the range of 10.0 - 10.6 eV cannot be calculated.

[0125] Please refer to Figure 8 , the double - ultraviolet - light - window photoionization sensor detects IBE. The IP value of isobutene is 9.43 eV, so CaF 2 and MgF 2 windows can both generate ions for IBE. Figure 8 shows the response of the double - ultraviolet - light - window photoionization sensor to 25 ppm of IBE (with nitrogen as the balance gas). Since the ultraviolet light transmission on the MgF 2 side is larger and the energy is stronger, for the same IBE concentration, the ion current generated on the MgF 2 side is larger and the signal is stronger. The ratio of the signal intensities on both sides for the same concentration of IBE is about 4.5 times.

[0126] Please refer to Figure 9 , the double - ultraviolet - light - window photoionization sensor detects ammonia. The IP value of ammonia is 10.18 V, so only the MgF 2 window can generate ions for ammonia, while the CaF 2 window cannot effectively generate ions. Figure 9 shows the response of the double - window PID device to 20 ppm of ammonia (with nitrogen as the balance gas). Since the ultraviolet light on the MgF 2 side contains ultraviolet light of 10.6 eV, so there is an obvious response signal on the MgF 2 side, while no signal is generated on the CaF 2 side. Thus, it is determined that the measured gas does not contain gases with IP values lower than 10.0 eV, but contains gases with ionization energies exceeding 10.0 eV and not exceeding 10.6 eV.

[0127] Please refer to Figure 10 , the double - ultraviolet - light - window photoionization sensor detects a mixed gas of ammonia and isobutene (IBE). The IP value of isobutene is 9.43 eV, and the IP value of ammonia is 10.18 V. So only the MgF 2 window can generate ions for ammonia and IBE, while the CaF 2 window can only effectively generate ions for IBE. Figure 10 shows the response of the double - window PID device to a mixed gas of 20 ppm of ammonia and 25 ppm of IBE (with nitrogen as the balance gas). Since the ultraviolet light on the MgF 2 side contains ultraviolet light of 10.6 eV, so MgF2 A distinct response signal was generated on one side, while for CaF 2 on the other side, it was only the signal of IBE. It can be observed that the signal ratio of the two sides was 6.2, exceeding the ratio when only IBE was present (according to the reference Figure 8 which was 4.5). Thus, it was determined that the mixed gas contained a gas with an IP value exceeding 10.0 eV. Thus, it was determined that the gas to be measured contained a gas with an IP value lower than 10.0 eV (isobutene), and also contained a gas with an ionization energy exceeding 10.0 eV and not exceeding 10.6 eV (ammonia).

[0128] From the above examples, it can be seen that in a photoionization sensor with a dual ultraviolet light window, multiple gases in the gas to be measured can be detected, increasing the classification information of the gas to be measured based on ionization energy. Moreover, by sharing a single ultraviolet light source, the ultraviolet light sources, gas concentrations, purities, etc. of each ultraviolet light window are almost the same, not only enabling the detection of different gas types but also improving the classification ability of the photoionization sensor when detecting gases with different ionization energies.

[0129] In this application, the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the drawings, and is only used to illustrate the relative positional relationship between each component or constituent part, without particularly limiting the specific installation orientation of each component or constituent part.

[0130] Moreover, in addition to being able to represent an orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to the specific circumstances.

[0131] In addition, the terms "install", "set", "provided with", "connect", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there can also be an internal connection between two devices, elements, or constituent parts. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0132] In addition, the structures, proportions, sizes, etc. depicted in the drawings of the present application are only used to cooperate with the content disclosed in the specification for those skilled in the art to understand and read, and are not used to limit the implementation conditions of the present application. Therefore, they do not have technical substantial significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that the present application can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present application.

Claims

1. A photoionization sensor for differentiating gas types, characterized in that, it includes: an ultraviolet lamp module, a sensor body, an ion current receiving electrode pair, an amplification circuit, and an output module; a gas flow region and an information processing region are provided on the sensor body; at least two ultraviolet light windows are provided on the ultraviolet lamp module, and the ultraviolet light spectral components emitted by each ultraviolet light window are different. The ultraviolet lamp module is disposed in the gas flow region, and the ultraviolet light windows are used to emit ultraviolet light after an ultraviolet light source is generated by the ultraviolet lamp module. The materials of the multiple ultraviolet light windows are different; at least two of the ion current receiving electrode pairs are installed in the gas flow region, and the ion current receiving electrode pairs are placed in front of the ultraviolet light windows. The ion current receiving electrode pairs are used to receive signals generated when the gas to be measured is ionized; at least two of the amplification circuits are installed in the information processing region. The ion current receiving electrode pairs are connected to the amplification circuits, and the amplification circuits are used to process the signals collected by the ion current receiving electrode pairs; the output module is disposed in the information processing region, the output module is connected to the amplification circuit, and the output module is used to receive and generate analysis data for differentiating the gas to be measured based on the ionization energy threshold according to the signals processed by the amplification circuit; the ultraviolet lamp module includes an AC voltage module, an ultraviolet light window, an ultraviolet excitation electrode pair, an ultraviolet lamp body, and a working gas; the ultraviolet lamp body contains the working gas and emits ultraviolet light under the excitation of the ultraviolet excitation electrode pair; at least two ultraviolet light windows are provided on the ultraviolet lamp body. After the emitted ultraviolet light generated by the working gas passes through the ultraviolet light windows, the spectral components emitted by each ultraviolet light window are different; the ultraviolet excitation electrode pair is installed on the ultraviolet lamp body, and the ultraviolet excitation electrode pair is used to excite the working gas to generate an ultraviolet light source; the AC voltage module is connected to the ultraviolet excitation electrode pair, and the AC voltage module is used to provide a high-voltage AC voltage to the ultraviolet excitation electrode pair; In the ultraviolet lamp module with double ultraviolet light windows, the ultraviolet lamp body is a cylindrical glass tube. First, one ultraviolet lamp mounting opening of the cylindrical glass tube is bonded with an ultraviolet light window using low-temperature glass powder at high temperature to achieve a semi-open and semi-closed structure. Subsequently, low-temperature glass powder is added to the other ultraviolet lamp mounting opening of the cylindrical glass tube, and the above device is sealed in a low-pressure environment filled with a working gas. Then, it is heated to the working temperature of the low-temperature glass powder and pasted. Subsequently, it is cooled and connected to the atmosphere. After installing the ultraviolet excitation electrode pair, the production of the vacuum ultraviolet lamp module with double windows is completed.

2. The photoionization sensor according to claim 1, characterized in that, the AC voltage module includes a high-voltage power supply module and a high-voltage power supply conversion module; the high-voltage power supply module is connected to the high-voltage power supply conversion module; the high-voltage power supply conversion module is connected to the ultraviolet excitation electrode pair, and the high-voltage power supply conversion module is used to supply electrical energy to the ultraviolet excitation electrode pair.

3. The photoionization sensor according to claim 1, It is characterized in that the ultraviolet lamp module further includes a gas adsorbent; the gas adsorbent is contained in the ultraviolet lamp module, and the gas adsorbent is used to adsorb impurity gases in the ultraviolet lamp module.

4. The photoionization sensor according to any one of claims 1 to 3, It is characterized in that the gas flow region includes an air inlet, an exhaust port, and an ionization region; the air inlet is provided on the sensor body, and the gas to be measured enters the ionization region through the air inlet, and the gas to be measured is ionized in the ionization region; the exhaust port is provided on the sensor body, and the exhaust port is used to extract the gas to be measured from the ionization region.

5. The photoionization sensor according to claim 4, It is characterized in that the gas flow region further includes an air pump for pumping the gas to be measured into the ionization region.

6. The photoionization sensor according to claim 4, It is characterized in that the gas flow region further includes an exhaust pump for discharging the gas to be measured from the ionization region.

7. The photoionization sensor according to any one of claims 1 to 3, It is characterized in that the ion current receiving electrode pair is placed parallel to the ultraviolet light window.

8. The photoionization sensor according to any one of claims 1 to 3, It is characterized in that the ion current receiving electrode pair is placed perpendicular to the ultraviolet light window.

9. The photoionization sensor according to any one of claims 1 to 3, It is characterized in that the output module includes a logic judgment module and an information output module; the logic judgment module is connected to the amplifier circuit, and the logic judgment module is used to analyze the signal processed by the amplifier circuit; the logic judgment module is connected to the information output module, and the information output module is used to output analysis data for distinguishing the gas to be measured based on the ionization energy threshold.

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