A self-cleaning PID gas sensor

Abstract

The utility model provides a kind of self-cleaning PID gas sensor, including cavity and the ultraviolet light source being arranged in cavity, a high frequency electric field generator, an electronic collection electrode, current voltage conversion circuit and control device, the electronic collection electrode includes polytetrafluoroethylene shell and inserts in the metal electrode piece of polytetrafluoroethylene shell inner cavity surface;The polytetrafluoroethylene shell is further provided with carbon nanotube film, and the carbon nanotube film is further provided with electric connection point, and the control device is connected by electric connection point, to be energized to generate heat under the control of the control device;Further, the surface of the electronic collection electrode is provided with piezoelectric ceramic, and the piezoelectric ceramic is vibrated under the control of the control device.In this way, PID gas sensor not only improves the accuracy of detection, but also enhances the reliability and durability of the equipment.

Description

Technical Field

[0001] This utility model relates to the field of gas sensors, specifically to a self-cleaning PID gas sensor. Background Technology

[0002] PID (Photoionization Detector) gas sensors are widely used in environmental monitoring, petrochemical process control, industrial emission detection, and indoor air quality monitoring due to their high sensitivity and fast response. Currently, commonly used PID sensors in industrial settings are small in size, with an ultraviolet light source bulb positioned at the center of the sensor, above which is a tiny chamber. Gas diffuses freely into the chamber and undergoes ionization. The ionized charged ions are driven to move by the electric field generated by the upper and lower electrodes (gates) of the tiny chamber, forming a current signal. This current intensity is proportional to the gas concentration and can be used for VOCs monitoring.

[0003] However, in complex environments such as high humidity, high concentration, or long-term continuous VOCs, existing PID sensors have the following significant problems:

[0004] (1) Gate corrosion: The upper and lower plates (gates) inside the cavity are gradually corroded by VOCs after long-term use, resulting in a decrease in sensor sensitivity.

[0005] (2) Ultraviolet light source pollution: The light-emitting window of the ultraviolet light source bulb is easily polluted by VOCs in the industrial site, which reduces the ultraviolet light transmittance and thus affects the detection accuracy.

[0006] (3) Humidity effects and false alarms: In high humidity environments, water vapor enters the tiny cavity of the sensor and, due to the extremely small gap between the electrodes, easily condenses into droplets, leading to false short circuits. In particular, when the grid is corroded, its surface is more likely to adsorb water droplets, further increasing the risk of short circuits.

[0007] Traditional solutions include adding pre-filters, heating elements, mechanical fans, or other purging devices. While pre-filters can address some moisture issues, they may affect the sampling efficiency of PID gas sensors and have limited desorption capabilities for VOCs. Adding heating elements can partially mitigate the effects of moisture, but it presents challenges such as high energy consumption and safety hazards. Adding mechanical fans or other purging devices can reduce residual gas, but it may affect measurement stability and increase equipment size and complexity. Furthermore, the sensitivity of PID gas sensors may decrease after prolonged use, further impacting monitoring reliability. To address this issue, an ideal solution has been sought.

[0008] In order to solve the above problems, people have been seeking an ideal technological solution. Utility Model Content

[0009] The purpose of this invention is to address the shortcomings of existing technologies by providing a self-cleaning PID gas sensor to solve the problems of high energy consumption, reduced gas sampling efficiency and measurement stability, and large and complex size associated with traditional cleaning methods.

[0010] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0011] A self-cleaning PID gas sensor is provided, comprising a cavity and an ultraviolet light source, a high-frequency electric field generator, an electron collecting electrode, a current-to-voltage conversion circuit, and a control device disposed within the cavity; wherein the electron collecting electrode comprises a polytetrafluoroethylene (PTFE) housing and a metal electrode sheet embedded in the inner surface of the PTFE housing; a carbon nanotube film is further disposed within the PTFE housing, and an electrical connection point is disposed on the carbon nanotube film, which is connected to the control device for generating heat under the control of the control device.

[0012] Furthermore, the surface of the electron collecting electrode is provided with piezoelectric ceramic, which is electrically connected to the control device for vibration under the control of the control device.

[0013] Furthermore, the piezoelectric ceramic is surface-mounted on the surface of the electron collecting electrode.

[0014] Furthermore, the vibration frequency of the piezoelectric ceramic is 25-45 kHz.

[0015] This invention possesses significant substantive features and substantial advancements compared to existing technologies. Specifically, it employs a carbon nanotube film, which better conforms to the inner cavity of the electron collecting electrode. In-situ heating ensures uniform heat distribution, preventing localized overheating or dead zone effects. This heating layer not only enhances the PID sensor's resistance to condensation in humid environments but also efficiently and with low power desorbs solid or liquid residues formed by VOCs pollutants inside the PID sensor, thus preventing electrode corrosion and maintaining detection sensitivity.

[0016] Furthermore, piezoelectric ceramics are installed on the surface of each electron collecting electrode. The high-frequency oscillation technology of the piezoelectric ceramics is used to vibrate the droplets on the electrode surface into gas molecules or mist-like microdroplets. Combined with the heating system, the saturated vapor pressure of the droplets is increased, resulting in efficient evaporation and avoiding false alarms due to short circuits. In addition, the high-frequency oscillation generated by the vibration characteristics of the piezoelectric ceramics also promotes the desorption of VOCs from the sensor surface, effectively removing gas residues, thereby improving the sensor's response speed and accuracy and extending its service life.

[0017] Furthermore, through innovative structural design, this utility model solves the application challenges of PID gas sensors in extreme environments, addresses the problems of high power consumption and slow purification of traditional heaters, and is particularly suitable for low temperature, high humidity, and high VOC environments. It improves the stability, accuracy, and long-term durability of PID gas sensors in high humidity and high concentration VOC environments, meeting the high standards required for environmental monitoring and industrial applications. Attached Figure Description

[0018] Figure 1 This is a system block diagram of Embodiment 1 of this utility model.

[0019] Figure 2 This is a structural schematic diagram of Embodiment 1 of the present invention.

[0020] Figure 3 This is a system block diagram of Embodiment 2 of this utility model.

[0021] Figure 4 This is a structural schematic diagram of Embodiment 2 of this utility model.

[0022] Figure 5 This is a flowchart illustrating Embodiment 2 of the present invention.

[0023] Figure 6 This is a system block diagram of Embodiment 3 of this utility model.

[0024] In the figure: 1. Carbon nanotube film; 2. Metal electrode sheet; 3. Piezoelectric ceramic; 4. Polytetrafluoroethylene shell; 5. Ultraviolet light source. Detailed Implementation

[0025] In the application of PID gas sensors, especially under extreme environmental conditions such as high humidity and high concentration of VOCs, existing technologies have significant shortcomings and defects.

[0026] The technical solution of this utility model will be further described in detail below through specific embodiments.

[0027] Example 1

[0028] This embodiment provides a self-cleaning PID gas sensor, such as... Figure 1 and Figure 2 As shown, it includes a cavity and an ultraviolet light source 5, a high-frequency electric field generator, an electron collecting electrode, a current-voltage conversion circuit, and a control device disposed in the cavity. The control device is connected to the ultraviolet light source through the high-frequency electric field generator and is used to drive the ultraviolet light source to generate ultraviolet light, which ionizes the gas entering between the electron collecting electrodes.

[0029] The electron collecting electrode collects electrons generated by ionization;

[0030] The current-to-voltage conversion circuit is connected to the electron collection electrode, and the current-to-voltage conversion circuit is also connected to the control device through a filter circuit module to convert the collected signal into a voltage signal that the control device can recognize.

[0031] Specifically, the electron collecting electrode includes a polytetrafluoroethylene (PTFE) housing 4 and a metal electrode sheet 2 embedded in the inner surface of the PTFE housing 4; a carbon nanotube film 1 is also disposed inside the PTFE housing 4, and an electrical connection point is disposed on the carbon nanotube film 1, which is connected to the control device to generate heat under the control of the control device.

[0032] Carbon nanotube films (CNTFs) exhibit significant application potential in the field of electronic device heating due to their excellent electrothermal conversion efficiency and high-temperature stability. The carbon nanotube films are stable up to 650°C in air, which is crucial for high-temperature heating applications. Furthermore, their thickness of less than 20 μm, along with their thin and flexible properties, allows for tight bonding with the electrode cavity. In this embodiment, the carbon nanotube film 1 is encased in a polytetrafluoroethylene shell to provide insulation and prevent environmental interference. Moreover, the carbon nanotube film 1 can provide in-situ heating, ensuring even heat distribution and avoiding localized overheating or dead zone effects, while maintaining the flexibility and portability of the PID gas sensor.

[0033] During use, the temperature of the PID sensor cavity is controlled by switching the carbon nanotube film 1 on and off and adjusting its power to prevent water vapor condensation. In high humidity environments, the high temperature promotes an increase in the saturated vapor pressure of droplets and VOCs gas residues on the electron collection electrode inside the PID sensor, thereby promoting gas desorption and making them easier to remove, reducing drift false alarms.

[0034] Example 2

[0035] The difference between this embodiment and Embodiment 1 is that: Figures 3-4 As shown, each electron collecting electrode is further provided with a piezoelectric ceramic 3 on its surface, which is electrically connected to the control device to vibrate under the control of the control device.

[0036] Piezoelectric ceramics, as a multifunctional ceramic material with excellent piezoelectric effect, are highly favored for their high-frequency oscillation characteristics, good thermal stability, moderate cost, high frequency stability, and durability in ultrasonic cleaning of electronic devices. They can rapidly convert electrical energy into high-frequency oscillations, generating powerful impact forces that penetrate deep into the tiny gaps and pores of electronic devices.

[0037] In this specific embodiment, the piezoelectric ceramic 3 and the electron collecting electrode are mounted in a surface-mount manner, forming a local resonant structure. High-frequency micro-vibration is used to vibrate the droplets on the electrode surface into gaseous molecules or mist-like droplets. Combined with the heating system, this increases the saturated vapor pressure of the droplets, enabling efficient evaporation and preventing false short-circuit alarms. Furthermore, the vibration can disrupt the VOCs molecular adsorption layer on the electrode surface, inhibiting deposition and improving long-term stability. This synergistic structure maximizes the use of oscillation and thermodynamic effects, solving the problems of high power consumption and slow removal in traditional heaters, and is particularly suitable for low-temperature, high-humidity, and high-VOC environments.

[0038] Furthermore, in actual use, the vibration frequency of the piezoelectric ceramic 3 is controlled to be 25kHz - 45kHz, and the frequency and intensity can be dynamically adjusted by the control device to adapt to different humidity and gas load conditions without damaging other electronic components.

[0039] It is understandable that this embodiment is the first to couple and solve the problems of water vapor-induced electrode short circuit and VOCs-induced corrosion in an integrated manner. Specifically, the high-frequency oscillation of the piezoelectric ceramic 3 can prevent water droplets from staying for a long time and avoid the formation of conductive paths. The carbon nanotube film 1 increases the local temperature, causing the saturated vapor of the droplets to rise, ensuring that water molecules or VOCs molecules remain in a gaseous state and do not condense. At the same time, it continuously removes VOCs adsorption residues, solving the problem of false alarms due to abnormal baseline drift from the source.

[0040] like Figure 5 The image shows one possible method of using the PID gas sensor, with the following specific steps:

[0041] After power-on, the system first determines whether an active cleaning command has been received. If an active cleaning command has been received, the system controls the carbon nanotube film 1 and the piezoelectric ceramic 3 to work together. After a period of time, the system checks whether a gas signal is present. If it is present, the system starts the normal detection process and outputs the detection result. If it is not present, the system returns to determine whether an active cleaning command has been received again.

[0042] If no active cleaning command is received, it is determined whether the sensor baseline is abnormal. If it is abnormal, the carbon nanotube film 1 and the piezoelectric ceramic 3 are controlled to work together. After a period of time, it is detected whether there is a gas signal. If there is, the normal detection process is started and the detection result is output. If there is no gas signal, it returns to determine whether an active cleaning command has been received again.

[0043] If no active cleaning command is received and the sensor baseline is normal, it is determined that the cumulative time meets the cleaning cycle triggering condition, and the carbon nanotube film 1 and the piezoelectric ceramic 2 are controlled to work together. After a period of time, it is detected whether there is a gas signal. If there is, the normal detection process is started and the detection result is output. If there is no gas signal, it is returned to determine whether an active cleaning command has been received.

[0044] Furthermore, controlling the coordinated operation of the carbon nanotube film 1 and the piezoelectric ceramic 3 can be achieved by controlling the simultaneous operation of the carbon nanotube film 1 and the piezoelectric ceramic 3 in real time, that is, controlling the carbon nanotube film 1 to be energized and heated while simultaneously controlling the piezoelectric ceramic to start oscillation; or the operation of the carbon nanotube film 1 and the piezoelectric ceramic 3 can be controlled in stages.

[0045] Specifically, the phased operation includes the following three stages: the first stage is the preheating stage, during which only the carbon nanotube film 1 is controlled to heat the electron collecting electrode; the second stage is the coordinated oscillation stage, during which the piezoelectric ceramic 3 is activated to resonate and clean the electron collecting electrode; and the third stage is the evaporation stage, during which the temperature rise is maintained and all surface residues are removed.

[0046] Example 3

[0047] The difference between this embodiment and Embodiment 1 is that: Figure 6 As shown, a temperature and humidity sensor is also provided on the outside of the cavity, which is used to collect ambient temperature.

[0048] The control device is connected to the temperature and humidity sensor and controls the operation of the flexible heating device and the piezoelectric ceramic according to the ambient temperature and humidity data.

[0049] In low-temperature environments, when the gas monitored by traditional PID sensors comes into contact with the sensor, condensation is likely to occur, especially at the electron collection electrode. The droplets generated by condensation can affect the transmission of current, and prolonged contact can also lead to corrosion of the electron collection electrode.

[0050] In this embodiment, the PID gas sensor automatically activates the carbon nanotube film 1 in low-temperature environments, maintaining the electron collecting electrode at a certain high temperature to prevent gas condensation. If droplets adhere to the electron collecting electrode, the surface vapor pressure of the droplets increases under high temperature, and the vibration caused by the activation of the piezoelectric ceramic 3 further promotes the evaporation of the droplets, thus achieving a self-cleaning effect. In this way, the PID gas sensor not only improves the accuracy of detection but also enhances the reliability and durability of the equipment.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it; although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this utility model or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the technical solution claimed by this utility model.

Claims

1. A self-cleaning PID gas sensor, comprising a cavity and an ultraviolet light source, a high-frequency electric field generator, an electron collecting electrode, a current-to-voltage conversion circuit, and a control device disposed within the cavity, characterized in that, The electron collecting electrode includes a polytetrafluoroethylene (PTFE) shell and a metal electrode sheet embedded in the inner surface of the PTFE shell. A carbon nanotube film is also disposed inside the PTFE shell, and an electrical connection point is disposed on the carbon nanotube film. The control device is connected through the electrical connection point to generate heat under the control of the control device.

2. The self-cleaning PID gas sensor according to claim 1, characterized in that: The surface of the electron collecting electrode is provided with piezoelectric ceramic, which is electrically connected to the control device to vibrate under the control of the control device.

3. The self-cleaning PID gas sensor according to claim 2, characterized in that: The piezoelectric ceramic is surface-mounted on the surface of the electron collecting electrode.

4. A self-cleaning PID gas sensor according to claim 2 or 3, characterized in that: A temperature and humidity sensor is also provided on the outside of the cavity, and the temperature and humidity sensor is used to collect the ambient temperature. The control device is connected to the temperature and humidity sensor and controls the flexible heating device and / or the piezoelectric ceramic to work based on the ambient temperature and humidity data.

5. A self-cleaning PID gas sensor according to claim 4, characterized in that: The vibration frequency of the piezoelectric ceramic is 25-45 kHz.

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