Device for measuring VOCs (Volatile Organic Compounds) through adsorption-thermal desorption

Abstract

The utility model discloses an adsorption-thermal desorption device for measuring VOCs (volatile organic compounds), which is characterized in that a drying device, an adsorption pipe, a cooling pipe, a sensor array air chamber and an air pump which are sequentially connected are arranged, air enters a pipeline after the air pump is opened, steam in the air is removed by the drying device firstly, and the influence of the steam on detection is removed; then air passes through the adsorption pipe to complete gas enrichment, VOCs gas is heated through the heating belt to be gradually desorbed from the adsorption material, the gas is transmitted through the gas pipe, cooled through the cooling pipe and then introduced into the sensor array gas chamber to be detected, and the specific VOCs gas molecules existing in the air and the corresponding concentration of the VOCs gas molecules are checked through the sensor array. The whole device is low in detection limit and low in measurement cost.

Description

Technical Field

[0001] The utility model belongs to the technical field of VOCs gas monitoring, in particular to an adsorption-thermal analysis device for measuring VOCs. Background Art

[0002] Volatile organic pollutants (VOCs) are a class of highly volatile organic compounds. Excessive VOCs will have a negative impact on air quality and human health. Since 2019, the country has stepped up its efforts to control VOCs. The number of VOCs monitoring sites has increased year by year, and the monitoring methods have gradually changed. The old sampling and analysis technology can no longer meet current needs, and now small portable devices are needed for real-time monitoring.

[0003] VOCs detection device is a device specially designed to detect the concentration of VOCs in the atmosphere. It is divided into portable VOCs detector, fixed VOCs detection system, online VOCs analyzer, remote sensing VOCs detector. Portable VOCs detector has the advantages of portability, fast response, and wide applicability. It has been widely used in many fields. The most common portable VOCs detector is the metal oxide semiconductor VOCs sensor, which has high sensitivity, good stability, small size and low cost.

[0004] Currently, there are two problems with the application of metal oxide semiconductor VOCs sensors, namely poor selectivity and high detection limit. Due to poor selectivity, the sensor responds to multiple gases, which makes it difficult to distinguish which gas has an impact in a complex environment, resulting in inaccurate measurement results. Metal oxide semiconductor VOCs sensors have shown excellent performance in detecting high-concentration VOCs and can accurately measure ppb-level (mg / L) VOCs. However, for the detection of VOCs at the ppm (ug / L) and ppt (ng / L) levels in the air, its sensitivity will be limited, resulting in a higher detection limit, which affects its accuracy and reliability in low-concentration environments. Utility Model Content

[0005] The utility model provides an adsorption-thermal analysis device for determining VOCs, which solves the problem of low detection accuracy of VOCs gas molecules in a low-concentration environment.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] A device for determining VOCs by adsorption-thermal analysis comprises a drying device, an adsorption tube, a cooling tube, a sensor array air chamber and an air pump connected in sequence, wherein the adsorption tube is provided with a heating belt, the sensor array air chamber is provided with a sensor array, and the sensor array is provided with a plurality of metal oxide semiconductor gas sensors for detecting different VOCs molecules.

[0008] Preferably, the drying device, adsorption tube, cooling tube, sensor array air chamber and air pump are connected by a polytetrafluoroethylene air pipe.

[0009] Preferably, the cooling tube is spiral-shaped.

[0010] Preferably, the adsorption tube is filled with VOCs adsorption material.

[0011] Preferably, the heating belt completely wraps the same position of the VOCs adsorption material on the outer surface of the adsorption tube.

[0012] Preferably, a support frame is provided at the bottom of the adsorption tube.

[0013] Preferably, the sensor array air chamber is machined from a solid resin block.

[0014] Preferably, the air pump is driven by a motor.

[0015] Preferably, a circular hole is provided at the bottom of the sensor array air chamber, and the metal oxide semiconductor gas sensor is nested in the hole.

[0016] Preferably, a plurality of the metal oxide semiconductor gas sensors are evenly arranged in the sensor array gas chamber.

[0017] Compared with the prior art, the utility model has the following beneficial effects: the utility model provides an adsorption-thermal analysis device for determining VOCs, which is provided with a drying device, an adsorption tube, a cooling tube, a sensor array air chamber and an air pump connected in sequence. After the air pump is turned on, air enters the pipeline, and the gas first passes through the drying device to remove water vapor in the air to remove the influence of water vapor on detection. Then the air passes through the adsorption tube to complete gas enrichment, and then the VOCs gas is heated by the heating belt to gradually desorb from the adsorption material. The gas is transmitted through the air pipe, first cooled by the cooling tube, and then passed into the sensor array air chamber for detection. The sensor array is used to check what specific VOCs gas molecules exist in the air and their corresponding concentrations. The detection limit of the entire device is low and the measurement cost is low.

[0018] Furthermore, the drying device, the adsorption tube, the air pump, the cooling tube, the sensor array air chamber and the air pump are connected by a polytetrafluoroethylene air pipe, and the polytetrafluoroethylene air pipe is resistant to high temperatures.

[0019] Furthermore, the cooling pipe is spiral-shaped, and has a good cooling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a connection diagram of an adsorption-thermal analysis device for determining VOCs in the utility model;

[0021] Figure 2 This is a schematic diagram of the air pump of the utility model;

[0022] Figure 3 This is a schematic diagram of the sensor array of the utility model;

[0023] Figure 4 This is a schematic diagram of the cooling pipe of the utility model;

[0024] Figure 5 This is a schematic diagram of the conversion head of the utility model;

[0025] Figure 6 This is a schematic diagram of the support frame of the utility model;

[0026] Figure 7 This is a schematic diagram of the drying device of the utility model;

[0027] Figure 8 It is a schematic diagram of the solid resin of the utility model;

[0028] Fig. 9 This is a schematic diagram of the gas channel of the gas chamber of the sensor array of the utility model;

[0029] Fig.10 This is a schematic diagram of the layout of the gas sensor of the utility model;

[0030] In the figure: 1. air pump; 2. sensor array air chamber; 3. sensor array; 4. cooling pipe; 5. adsorption tube; 6. heating belt; 7. drying device; 8. air pipe connection port; 9. air pump flow adjustment knob; 10. second air pipe connection port; 11. large-diameter reducer joint; 12. small-diameter reducer joint; 13. support frame; 14. drying device filler; 15. solid resin; 16. sensor array air chamber gas channel; 17. gas sensor. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0034] In the description of the embodiments of the present utility model, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the utility model product is usually placed when in use, it is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0035] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0036] In the description of the embodiments of the present utility model, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0037] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0038] The utility model provides an adsorption-thermal analysis device for determining VOCs, comprising a drying device 7, an adsorption tube 5, a cooling tube 4, a sensor array air chamber 2 and an air pump 1 connected in sequence, wherein the adsorption tube 5 is provided with a heating belt 6, the sensor array air chamber 2 is provided with a sensor array 3, and the sensor array 3 is provided with a plurality of metal oxide semiconductor gas sensors 17 for detecting different VOCs molecules.

[0039] The drying device 7, the adsorption tube 5, the cooling tube 4, the sensor array air chamber 2 and the air pump 1 are connected by a polytetrafluoroethylene air pipe.

[0040] like Figure 2 As shown, the air pump 1 is HilintecD35, and the air pump 1 is driven by a high-efficiency small motor to ensure stable working airflow. The air pipe connection port 8 is designed in a pagoda style for connecting a polytetrafluoroethylene air pipe to ensure the tightness and efficiency of airflow transmission. The air pump flow adjustment knob 9 can easily achieve precise adjustment of the gas flow through a convenient rotary switch to meet the needs of different scenarios.

[0041] like Figure 3 As shown, there are multiple circular holes at the bottom of the sensor array gas chamber, which are designed for nesting sensor probes. This innovative design not only optimizes the use area of ​​the gas chamber, but also significantly reduces the concentration change when the enriched gas enters the gas chamber, thereby greatly improving the accuracy and stability of gas detection.

[0042] The sensor array 3 is provided with a plurality of metal oxide semiconductor VOCs gas sensors, which are arranged in a row and the probes are nested and connected with the bottom of the sensor array gas chamber, so as to accurately detect and respond to changes in gas concentration in the environment. The second gas pipe connection port 10 is used to connect a polytetrafluoroethylene gas pipe.

[0043] like Figure 4 As shown, the cooling tube 4 is designed to be spiral, and the spiral cooling tube can increase the contact area with the air pipe, thereby improving the cooling efficiency. A coolant is installed in the cooling tube to effectively reduce the temperature of the thermal desorption VOCs gas, so that the temperature entering the air chamber is maintained at the optimal temperature, thereby improving the accuracy of the sensor.

[0044] like Figure 5 As shown, the reducer small-diameter joint 12 and the reducer large-diameter joint 11 are used to connect the adsorption tube and the air pipe, thereby sealingly connecting pipes of different diameters.

[0045] like Figure 6As shown, the adsorption tube 5 is a quartz hollow cylindrical tube, the middle part of the adsorption tube 5 is filled with VOCs adsorption material, and the outer surface of the adsorption tube is provided with a fully wrapped heating belt at the same position as the VOCs adsorption material, which is used to perform thermal desorption and desorption of the VOCs adsorption material in the adsorption saturation state. The adsorption tube 5 is supported by an adsorption tube support frame 13 below, and the heating belt is a rectangular sheet-shaped integrated heating belt, which can completely wrap the adsorption tube so that it is heated evenly.

[0046] like Figure 7 As shown, the drying device 7 is filled with a desiccant 14 for removing the influence of water vapor on detection, and an air pipe connection port is provided at the upper end for connecting the air pipe.

[0047] like Figure 8 As shown, the sensor array air chamber is made of a solid resin block 15, which has a gas channel and a sensor hole. The closed embedding ensures the airtightness of the device, and the single gas channel reduces the volume of gas introduced and reduces the dilution degree of the introduced gas.

[0048] Working principle:

[0049] Before use, fill the VOCs adsorption material into the adsorption tube 5 and check the air tightness and structural integrity of the device.

[0050] Turn on the sensor array 3 and turn on the air pump to effectively enrich the target gas. The gas then passes through a special adsorption tube 5, and the adsorption material adsorbs the VOCs in the gas at room temperature. After a preset adsorption cycle, turn on the heating belt 6. As the temperature gradually rises, the VOCs gas originally adsorbed on the material begins to thermally desorb and is transmitted through the air pipe. Before the gas enters the sensor array chamber 2, it first passes through the cooling tube 4 to lower its temperature to ensure that the sensor can perform detection under optimal working conditions.

[0051] The gas sensor 17 in the sensor array air chamber 2 will detect the concentration of VOCs gas in real time. The staff can determine the VOCs gas molecules by observing which sensor has a value change.

[0052] After the equipment is finished working, wait for the heating belt to return to room temperature and store the device.

[0053] This patent is an adsorption-thermal analysis device for determining VOCs, which has a simple overall structure and is easy to process, install and use. When the device is in use, it has a good adsorption effect, high thermal analysis efficiency, and the entire sensor array responds quickly and responds to many VOCs gases, making it suitable for indoor or outdoor low-concentration VOCs detection.

[0054] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments and application fields, and the above-mentioned specific embodiments are merely illustrative and instructive, rather than restrictive. Under the guidance of the specification, a person skilled in the art can make many forms without departing from the scope of protection of the claims of the present invention, all of which belong to the scope of protection of the present invention.

Claims

1. An adsorption-thermal analysis device for determining VOCs, characterized in that: The invention comprises a drying device (7), an adsorption tube (5), a cooling tube (4), a sensor array air chamber (2) and an air pump (1) which are connected in sequence, wherein the adsorption tube (5) is provided with a heating belt (6), the sensor array air chamber (2) is provided with a sensor array (3), and the sensor array (3) is provided with a plurality of metal oxide semiconductor gas sensors (17) for detecting different VOCs molecules.

2. The device for determining VOCs by adsorption-thermal analysis according to claim 1, characterized in that: The drying device (7), the adsorption tube (5), the cooling tube (4), the sensor array air chamber (2) and the air pump (1) are connected by a polytetrafluoroethylene air pipe.

3. The device for determining VOCs by adsorption-thermal analysis according to claim 1, characterized in that: The cooling pipe (4) is spiral-shaped.

4. The device for determining VOCs by adsorption-thermal analysis according to claim 1, characterized in that: The adsorption tube (5) is filled with VOCs adsorption material.

5. The device for determining VOCs by adsorption-thermal analysis according to claim 4, characterized in that: The heating belt (6) completely wraps the same position of the VOCs adsorption material on the outer surface of the adsorption tube (5).

6. The device for determining VOCs by adsorption-thermal analysis according to claim 1, characterized in that: A support frame (13) is provided at the bottom of the adsorption tube (5).

7. The device for determining VOCs by adsorption-thermal analysis according to claim 1, characterized in that: The sensor array air chamber (2) is made of a solid resin block (15).

8. The device for determining VOCs by adsorption-thermal analysis according to claim 1, characterized in that: The air pump (1) is driven by a motor.

9. The device for determining VOCs by adsorption-thermal analysis according to claim 1, characterized in that: A circular small hole is provided at the bottom of the sensor array air chamber (2), and the metal oxide semiconductor gas sensor (17) is nested in the small hole.

10. The device for determining VOCs by adsorption-thermal analysis according to claim 1, characterized in that: The plurality of metal oxide semiconductor gas sensors (17) are evenly arranged in the sensor array gas chamber (2).

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