CN112557481A - VOCs gas detection system and method based on ultraviolet light assistance - Google Patents

Abstract

The invention discloses a VOCs gas detection system and a VOCs gas detection method based on ultraviolet light assistance, wherein the VOCs gas detection system comprises a gas detection device, a mass flow controller, a vacuum pump, a digital source meter, a computer, a plurality of gas pipes and a plurality of leads; the gas detection device comprises an LED ultraviolet light source, a sensor and a quartz sealed cavity, wherein a gas channel allowing target gas to pass through is arranged at the edge of the quartz sealed cavity, and the gas channel comprises at least one inlet and at least one outlet; the mass flow controller is used for controlling the target gas to enter the gas detection device at a specified flow rate; the vacuum pump is used for accelerating gas exchange in the gas detection device; the digital source meter is used for measuring the current of the sensitive element; the computer is used for controlling the mass flow controller and the digital source meter.

Description

VOCs gas detection system and method based on ultraviolet light assistance

Technical Field

The invention relates to the technical field of gas sensors, in particular to a VOCs gas detection system and method based on ultraviolet light driving.

Background

In China, VOCs refer to organic compounds with saturated vapor pressure of more than 70 Pa at normal temperature and boiling point of below 260 ℃ at normal pressure, or all organic compounds with vapor pressure more than or equal to 10 Pa and volatility and VOCs participate in the formation of ozone and secondary aerosol in atmospheric environment at the temperature of 20 ℃, it has important influence on regional atmospheric ozone pollution and PM2.5 pollution, most VOCs have special unpleasant odor and have toxicity, irritation, teratogenicity and carcinogenic effect, in addition, VOCs are important precursors for causing urban haze and photochemical smog and mainly come from the processes of coal chemical industry, petrochemical industry, fuel coating manufacturing, solvent manufacturing and using and the like, so that the real-time monitoring of the concentration of the VOCs is a very important and urgent task.

The gas sensor is a basic component of an environment monitoring system and also an important technical basis for realizing automatic test control, in an industrial area and a living area, the portable and high-sensitivity gas sensor can greatly improve the environment monitoring capability, at present, although many technical means can realize detection on VOCs gas with sub-ppm level concentration, such as spectrophotometry, electrochemical detection method, gas chromatography, liquid chromatography and the like, the methods still have great challenges in cost, operability and portability, and in order to deeply and quantitatively measure gas pollutants, especially the exhaust gas rich in VOCs, the flammable and explosive characteristics of VOCs are considered, and the research and development of a gas detection method with excellent performance at normal temperature is urgently needed.

The invention provides a VOCs gas detection system and method based on ultraviolet light drive, which adopt ultraviolet light assistance to replace traditional heating assistance, can reduce the working temperature of a gas sensor in the system to room temperature, and realize accurate detection of VOCs gas.

Disclosure of Invention

In view of this, the present invention provides a system and a method for detecting VOCs based on ultraviolet light assistance, which are used for detecting VOCs in a room temperature environment.

The embodiment of the invention provides a VOCs gas detection system and a VOCs gas detection method based on ultraviolet light assistance, wherein the VOCs gas detection system comprises a gas detection device, a mass flow controller, a vacuum pump, a digital source meter, a computer, a plurality of gas pipes and a plurality of leads; the gas detection device is used as a gas reaction environment of the sensor, and a gas channel allowing the target gas to pass through is arranged at the edge of the gas detection device and comprises at least one inlet and at least one outlet; the mass flow controller is used for controlling the target gas to enter the gas detection device at a specified flow rate; the vacuum pump is used for accelerating gas exchange in the gas detection device; the sensitive element comprises a quartz substrate, an interdigital electrode and a zinc oxide film coated on the interdigital electrode, the interdigital electrode and the zinc oxide film form a sensitive layer, and the quartz substrate is fixedly adhered in the gas detection device; the LED uv light source is set to 365nm uv light and is used to emit uv light towards the sensitive layer, such that the sensitive layer is in a uv light environment; the digital source meter is used for measuring the current of the sensitive element; the computer is used for controlling the mass flow controller and the digital source meter.

Further, the distance between the LED ultraviolet light source arranged in the gas detection device and the sensitive layer is 5 cm.

Further, the LED ultraviolet light source is movably arranged in the gas detection device.

Further, the LED ultraviolet light source and the sensitive layer are both positioned in the center of the plane of the sensing element.

Further, the light spot size of the LED ultraviolet light source is larger than the size of the sensitive layer.

Further, the mass flow controller is arranged outside the gas detection device and used for controlling the target gas and the clean air to enter the gas channel inlet arranged at the edge of the gas detection device at a specified flow rate.

Further, a vacuum pump is used to accelerate gas exchange within the gas detection apparatus.

Further, the digital source meter is connected to two ends of the electrode of the gas sensor and is used for measuring the current change of the gas sensor in the target gas after voltage is applied.

Further, the computer is used for controlling the mass flow controller and the digital source meter, and further processing and analyzing the measurement result of the digital source meter.

By the system and the method for detecting the VOCs gas based on the ultraviolet light assistance, which are disclosed by the embodiment of the invention, the interference of factors such as an external light source and dust on the sensor can be effectively prevented, the accuracy and the sensitivity of detecting and identifying the VOCs gas are improved, the VOCs gas can be detected at sub-ppm at room temperature under an ultraviolet light optical field of 365nm, the sensitivity is good, and the potential safety hazard caused by a common high-temperature working environment can be avoided.

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible and comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly described below.

Fig. 1 shows a schematic structural diagram of a system and method for detecting VOCs based on uv-assisted detection according to an exemplary embodiment of the present invention.

Fig. 2 shows a schematic structural diagram of a gas detection device according to an exemplary embodiment of the present invention.

Fig. 3 shows a schematic structural diagram of a sensing element according to an exemplary embodiment of the present invention.

Detailed Description

The embodiments of the present invention will be described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout, and which are described below with reference to the accompanying drawings, are exemplary only, and are not to be construed as limiting the invention.

With reference to fig. 1, 2, and 3, according to the gas detection system of the zinc oxide-based sensor in the ultraviolet light assisted mode according to the exemplary embodiment of the present invention, interference of external light sources, dust, and other factors on the sensor can be effectively blocked, accuracy and sensitivity of detecting and identifying the VOCs gas can be improved, sub-ppm detection can be achieved on the VOCs gas at room temperature under 365nm ultraviolet light, and the system has good sensitivity, so that potential safety hazards caused by a common high-temperature working environment can be avoided.

In conjunction with the embodiment shown in fig. 1, the present invention provides a system and a method for detecting VOCs based on uv-assisted detection, which includes a gas detection device 10, a mass flow controller 20, a vacuum pump 30, a digital source meter 40, a computer 50, and a plurality of gas pipes 60 and wires 70, wherein the mass flow controller 20 and the digital source meter 40 are controlled by the computer 50, wherein the mass flow controller 20 is used for controlling a target gas to enter the gas detection device 10 at a specified flow rate, the digital source meter 40 is connected across electrodes of the gas detection device 10 for measuring current changes of a gas sensor in the target gas after applying a voltage, and the vacuum pump 30 is used for accelerating gas exchange in the gas detection device 10.

Referring to fig. 1, the gas detection device 10 is used as a gas reaction environment of a sensor, and a gas channel allowing a target gas to pass through is arranged at the edge of the gas detection device 10, and the gas channel comprises at least one inlet and at least one outlet, in an alternative embodiment, the inlet and the outlet are designed in a manner that a gas pipe 80 is communicated, the gas flow at the inlet is controlled by a mass flow controller 20, and the outlet is communicated with a vacuum pump 30 to accelerate the gas exchange in the gas detection device 10.

Referring to fig. 1, the digital source meter 40 is connected to both ends of the electrode of the gas detecting device 10 to form a measuring circuit for measuring a current change of the gas detecting device 10 after contacting the target gas after applying a voltage, and the mass flow controller 20 is configured to control the target gas and the clean air to enter the gas channel inlet provided at the edge of the gas detecting device 10 at a predetermined flow rate.

In addition, the digital source meter 40 and the mass flow controller 20 are connected to the computer 50 by a plurality of leads 90 in a corresponding manner, so that the computer 50 can control the gas flow rate output by the mass flow controller 20, adjust the measurement accuracy and mode of the digital source meter 40, and read and store experimental data acquired by the digital source meter 40.

Referring to fig. 2, the gas detecting device 10 includes a sensing element 11, an LED ultraviolet light source 12 and a quartz casing 13, the quartz casing 13 of the gas detecting device 10 is made of high-purity quartz crystal, so that the gas detecting device 10 is used as a working environment of the sensing element 70 arranged in the device casing, and can ensure that the sensor is effectively prevented from being interfered by external light sources, dust and other factors, the sensing element 11 is used for detecting whether the gas entering the gas detecting device 10 contains VOCs and content, the LED ultraviolet light source 12 is movably arranged in the gas detecting device 10, the wavelength of the ultraviolet light can be set and fixed to 365nm, the distance between the LED ultraviolet light source 12 and the sensing element 40 is 5cm, and certainly, when different light intensities are required according to experimental requirements, the distance between the LED ultraviolet light source 12 and the sensing layer of the sensing element 11 can be adjusted by moving up and down, the light spot size of the LED ultraviolet light source 12 is larger than the size of the sensitive layer of the sensitive element 11, and the LED ultraviolet light source and the sensitive layer are both located at the center of the plane of the sensitive element 11, so that the LED ultraviolet light source arranged outside the gas detection device 10 can effectively reduce the working temperature required by the sensitive element arranged in the cavity to room temperature.

Referring to fig. 1 and 2, a detailed system and method for detecting VOCs based on uv-assisted detection are described as follows, a computer 50 controls a mass flow controller 20 to make a target gas enter a gas detection device 10 at a specified flow rate, a sensor 11 contacts and reacts with the target gas under the drive of uv light emitted from an LED uv light source 12, at this time, a digital source meter 40 connects two ends of an electrode of the sensor 11, can detect a current change of the sensor 11 in a measurement circuit and transmits the current change to the computer 50 in real time, a vacuum pump 30 is connected to a gas channel outlet arranged at the edge of the gas detection device 10 for accelerating gas exchange in the gas detection device 10, and at this time, when a current signal transmitted to the computer 50 by the digital source meter 40 tends to be stable during the detection of the target gas, the computer 50 controls a mass flow controller 80 to close the inflow of the target gas, and introducing clean air to the gas channel inlet arranged at the edge of the gas detection device 10 until the current signal transmitted to the computer 50 by the digital source meter 40 is stable again, namely completing one experiment.

Referring to fig. 3, the sensing element 11 includes a quartz substrate 111, an interdigital electrode 112, and a zinc oxide thin film 113 coated on the interdigital electrode 112, the interdigital electrode 112 and the zinc oxide thin film 113 form a sensing layer, the quartz substrate 111 is adhesively fixed (for example, glued and fixed) in the gas detection apparatus 10, and the sensing element 11 can achieve the same gas-sensitive effect in a high-temperature environment under the drive of ultraviolet light with a wavelength of 365nm, so that the detection system can achieve the detection of VOCs at normal temperature.

The above embodiments only express the embodiments of the present invention, and the description is more specific and detailed, but not understood as the limitation of the scope of the present invention, it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the concept of the present invention, and these all fall into the protection scope of the present invention.

Claims (9)

1. A VOCs gas detection system and method based on ultraviolet light assistance, comprising a gas detection device, a mass flow controller, a vacuum pump, a digital source meter, a computer, a plurality of gas pipes and a plurality of leads; the gas detection device comprises an LED ultraviolet light source, a sensor and a quartz sealed cavity, wherein a gas channel allowing target gas to pass through is arranged at the edge of the quartz sealed cavity, and the gas channel comprises at least one inlet and at least one outlet; the mass flow controller is used for controlling the target gas to enter the gas detection device at a specified flow rate; the vacuum pump is used for accelerating gas exchange in the gas detection device; the digital source meter is used for measuring the current of the sensitive element; the computer is used for controlling the mass flow controller and the digital source meter.

2. A system and method for uv-assisted based detection of gases in VOCs according to claim 1 wherein the gas detection device includes a sensing element and a LED uv source, the LED uv source being spaced from the sensing element by a distance of 5 cm.

3. The gas detection apparatus of claim 2, wherein the LED uv light source is removably disposed within the gas detection apparatus.

4. A gas detection device as claimed in claim 2 wherein the LED uv light source and the sensing element are both located in the centre of the plane of the sensing element.

5. A gas detection device as claimed in claim 2 wherein the LED uv light source has a spot size greater than the size of the sensing element.

6. A system and method for uv-assisted based detection of gases in VOCs according to claim 1 wherein mass flow controllers are located outside the gas detection assembly for controlling the flow of target gas and clean air into the gas channel inlets located at the edges of the gas detection assembly at specified rates.

7. A system and method for uv-assisted based detection of gases in VOCs according to claim 1 wherein a vacuum pump is used to accelerate gas exchange within the gas detection apparatus.

8. A system and method for uv-assisted based detection of VOCs gas in accordance with claim 1 wherein a digital source meter is connected across the electrodes of the sensing element for measuring the current change in the target gas of the gas sensor after applying a voltage.

9. A system and method for uv-assisted based detection of gases in VOCs according to claim 1, wherein the computer is adapted to control the mass flow controller and the digital source meter and to further process and analyze the measurements taken by the digital source meter.

Images