Water and CO2 removal device and volatile organic compound detection system

Abstract

The utility model discloses a water and CO2 removal device which comprises a CO2 removal mechanism and a water removal mechanism which are sequentially connected through a sample conveying pipeline, the CO2 removal mechanism at least comprises a CO2 adsorption pipe with an inner cavity filled with CO2 adsorbents, and the water removal mechanism at least comprises a Nafion drying pipe. The utility model further discloses a volatile organic compound detection system which comprises an automatic sample injector, a pre-concentration device and a detector, and the water and CO2 removal device is arranged between the sample injector and the pre-concentration device. The device has the advantages that the structure is simple, the moisture and CO2 removal rate is improved, and the detection result of the detector is more accurate and reliable.

Description

Technical Field

[0001] The utility model mainly relates to the technical field of volatile organic compound detection, in particular to a water removal and CO2 removal device and a volatile organic compound detection system. Background Art

[0002] With the rapid development of society, people's living standards are constantly improving, and they are paying more and more attention to environmental pollution. Among them, volatile organic compounds are widely valued for their high toxicity and great harm, and some of them are also carcinogenic, teratogenic, and mutagenic. Therefore, online detection of volatile organic compounds in the environment is very important. Conventional atmospheric VOCs material detection schemes mostly use automatic samplers, pre-concentrators and GCMS detectors. When detecting ultra-low trace levels (2ppt~200ppt) of atmospheric VOCs, especially for the detection of ODS and PFS substances, the presence of water and CO2 will interfere with the detection results. The presence of water will cause retention time drift, and CO2 will cover the target substance on the GCMS detector. Although the existing scheme is equipped with a cold trap for removing moisture and CO2 in the sample in the pre-concentrator, the removal rate of moisture and CO2 cannot meet the detection requirements of ultra-low trace levels (2ppt~200ppt), which will cause large data fluctuations, large linear deviations, and RSD values ​​out of range. Utility Model Content

[0003] In view of the technical problems existing in the prior art, the utility model provides a water removal and CO2 removal device and a volatile organic compound detection system which have a simple structure, improve the water and CO2 removal rate, and ensure that the detection result of the detector is more accurate and reliable.

[0004] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0005] A water removal and CO2 removal device comprises a CO2 removal mechanism and a water removal mechanism which are sequentially connected via a sample delivery pipeline. The CO2 removal mechanism comprises at least one CO2 adsorption tube whose inner cavity is filled with CO2 adsorbent, and the water removal mechanism comprises at least one Nafion drying tube.

[0006] As a further improvement of the utility model: the Nafion drying tube comprises an inner tube and an outer tube, the Nafion drying tube is provided with an inlet and an outlet connected to the inner tube, and a cavity for the flow of drying gas is formed between the inner tube and the outer tube.

[0007] As a further improvement of the utility model: it also includes a dry gas intake assembly and an exhaust assembly communicated with the cavity.

[0008] As a further improvement of the utility model: the dry gas intake assembly comprises an intake pipe, the intake end of the intake pipe is used to connect to an external gas source, and the outlet end of the intake pipe is communicated with the cavity.

[0009] As a further improvement of the utility model: the air inlet pipe is provided with a control valve for controlling the on-off of the dry gas and a flow valve for adjusting the pressure difference between the inner and outer pipes.

[0010] As a further improvement of the present invention: the exhaust assembly includes an exhaust pipe communicated with the cavity.

[0011] As a further improvement of the present invention: the CO2 adsorption tube comprises a tube body for filling the adsorbent, the tube body is arranged in a vertical direction, and straight-through joints are provided at both ends of the tube body, and the straight-through joints are connected to the tube body through locking nuts.

[0012] As a further improvement of the utility model: a heating assembly is provided around the sample delivery pipeline, the Nafion drying tube and the CO2 adsorption tube.

[0013] The utility model also discloses a volatile organic compound detection system, comprising an automatic sample injector, a pre-concentration device and a detector, wherein the water removal and CO2 removal device as described above is arranged between the automatic sample injector and the pre-concentration device.

[0014] As a further improvement of the present invention: the detector is a GCMS detector or a GC-FID detector.

[0015] Compared with the prior art, the advantages of the utility model are:

[0016] 1. The water removal and CO2 removal device of the utility model is provided with a CO2 adsorption tube and a Nafion drying tube. When the sample passes through the CO2 adsorption tube, the CO2 in the sample is removed by chemical reaction with the adsorbent, and the CO2 adsorption tube is arranged at the front end of the Nafion drying tube. The water in the sample will accelerate the reaction efficiency of CO2; then the water in the sample is removed by the membrane selection effect of the Nafion drying tube when passing through the Nafion drying tube. In this process, there is no loss of target detection substances and the introduction of interfering substances, which greatly improves the accuracy and reliability of the detection results of the detector.

[0017] 2. The volatile organic compound detection system of the utility model is provided with the above-mentioned water removal and CO2 removal device between the automatic sampler and the pre-concentration device. The CO2 in the sample is first removed by a CO2 adsorption tube, and then the water in the sample is removed by a Nafion drying tube. In the process of removing CO2 and water vapor, there is no loss of target substances and no introduction of interfering substances, which can meet the detection requirements of ultra-low trace levels (2ppt~200ppt) of VOCs substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the water removal and CO2 removal device of the utility model in a specific embodiment.

[0019] Figure 2 It is a structural schematic diagram of the CO2 removal mechanism of the utility model in a specific embodiment.

[0020] Figure 3 It is a structural schematic diagram of the volatile organic compound detection system of the utility model.

[0021] Legend:

[0022] 1. Sample delivery pipeline; 2. CO2 removal mechanism; 21. Tube body; 22. Straight connector; 23. Locking nut; 3. Water removal mechanism; 31. Sample inlet; 32. Sample outlet; 4. Air inlet assembly; 41. Air inlet pipe; 42. Control valve; 43. Flow valve; 5. Exhaust assembly; 6. Heating assembly; 100. Automatic sampler; 101. Pre-concentration device; 102. Detector. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0024] Embodiment 1

[0025] like Figure 1 to Figure 2 As shown, this embodiment discloses a water removal and CO2 removal device, including a CO2 removal mechanism 2 and a water removal mechanism 3 connected in sequence through a sample delivery pipeline 1, the CO2 removal mechanism 2 includes at least one CO2 adsorption tube with an inner cavity filled with a CO2 adsorbent, and the water removal mechanism 3 includes at least one Nafion drying tube.

[0026] The water removal and CO2 removal device in this embodiment is provided with a CO2 adsorption tube and a Nafion drying tube. When the sample passes through the CO2 adsorption tube, the CO2 in the sample is removed by chemical reaction with the adsorbent, and the CO2 adsorption tube is arranged at the front end of the Nafion drying tube. The water in the sample will accelerate the reaction efficiency of CO2; then, when the water in the sample passes through the Nafion drying tube, it is removed by the membrane selection effect of the Nafion drying tube. In this process, there is no loss of target detection substances and the introduction of interfering substances, which greatly improves the accuracy and reliability of the detection results of the detector.

[0027] In this embodiment, the Nafion drying tube includes an inner tube and an outer tube, and the Nafion drying tube is provided with an inlet 31 and an outlet 32 ​​connected to the inner tube, and a cavity for the flow of dry gas is formed between the inner tube and the outer tube. By providing a Nafion drying tube that is selective for water molecules, water molecules can pass through the membrane while the VOCs substances to be tested in the sample cannot pass through the pores on the membrane, thereby achieving water separation.

[0028] In this embodiment, a dry gas intake assembly 4 and an exhaust assembly 5 connected to the cavity are also included. Further, in a preferred embodiment, the dry gas intake assembly 4 includes an intake pipe 41, the intake end of the intake pipe 41 is used to connect to an external gas source, the outlet end of the intake pipe 41 is connected to the cavity, and the intake pipe 41 is provided with a control valve 42 for controlling the on and off of the dry gas and a flow valve 43 for adjusting the pressure difference between the inner and outer tubes, and the exhaust assembly 5 includes an exhaust pipe connected to the cavity. Dry gas is introduced into the cavity between the inner tube and the outer tube of the Nafion drying tube through the dry gas intake assembly 4, and the moisture in the cavity can be taken away in time and discharged in time through the exhaust pipe. The pressure difference between the inner and outer tubes can be guaranteed by the flow valve 43, thereby achieving the normal flow of the dry gas.

[0029] In this embodiment, the CO2 adsorption tube includes a tube body 21 for filling the adsorbent, the tube body 21 is arranged in the vertical direction, and straight joints 22 are provided at both ends of the tube body 21, and the straight joints 22 are connected to the tube body 21 through locking nuts 23. The CO2 adsorption tube adopts the method of air intake at the lower end and air outlet at the upper end, which can effectively increase the contact efficiency between the gas and the adsorbent, and the CO2 adsorption tube is arranged at the front end of the Nafion drying tube, using the water vapor in the sample to accelerate the reaction between CO2 and the adsorbent, and at the same time will not produce interfering organic matter.

[0030] In this embodiment, a heating assembly 6 is provided around the sample delivery pipeline 1, the Nafion drying tube and the CO2 adsorption tube. The heating assembly 6 can effectively reduce the adsorption and residue of the target substance in the pipeline, thereby reducing the impact on the detection accuracy.

[0031] Embodiment 2

[0032] like Figure 3 As shown, this embodiment discloses a volatile organic compound detection system, including an automatic sample injector 100, a pre-concentration device 101 and a detector 102, and a water removal and CO2 removal device as described in Example 1 is arranged between the automatic sample injector 100 and the pre-concentration device 101. The automatic sample injector 100 is connected to the sample inlet of the CO2 adsorption tube through a sample delivery pipeline 1, and the pre-concentration device 101 is connected to the sample outlet 32 ​​of the Nafion drying tube through the sample delivery pipeline 1, and a heating component 6 is arranged on the periphery of the sample delivery pipeline 1.

[0033] In this embodiment, the detector 102 is a GCMS detector; in other embodiments, the detector 102 may be a GC-FID detector.

[0034] Working process: The sample passes through the automatic sampler 100 in sequence through the CO2 adsorption tube, the Nafion drying tube, and is concentrated by the pre-concentration device 101 before entering the detector 102 for detection. When the sample passes through the CO2 adsorption tube, the CO2 in the gas sample is removed by chemical reaction with the adsorbent, and the water vapor in the sample accelerates the reaction between CO2 and the adsorbent. When passing through the Nafion drying tube, the moisture in the gas sample is removed by the membrane selection effect of the Nafion drying tube. In this process, there is no loss of target substances and introduction of interfering substances, which can meet the detection requirements of ultra-low trace levels (2ppt~200ppt) of VOCs substances.

[0035] The above are only preferred implementations of the utility model. The protection scope of the utility model is not limited to the above embodiments. All technical solutions under the idea of ​​the utility model belong to the protection scope of the utility model. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the utility model should be regarded as the protection scope of the utility model.

Claims

1. A water removal and CO2 removal device, characterized in that: The invention comprises a CO2 removal mechanism (2) and a water removal mechanism (3) which are connected in sequence via a sample delivery pipeline (1); the CO2 removal mechanism (2) comprises at least one CO2 adsorption tube whose inner cavity is filled with a CO2 adsorbent; and the water removal mechanism (3) comprises at least one Nafion drying tube.

2. The water removal and CO2 removal device according to claim 1, characterized in that: The Nafion drying tube comprises an inner tube and an outer tube. The Nafion drying tube is provided with an inlet (31) and an outlet (32) connected to the inner tube. A cavity for the flow of drying gas is formed between the inner tube and the outer tube.

3. The water removal and CO2 removal device according to claim 2, characterized in that: It also includes a dry gas intake assembly (4) and an exhaust assembly (5) which are in communication with the cavity.

4. The water removal and CO2 removal device according to claim 3, characterized in that: The dry gas intake assembly (4) comprises an intake pipe (41), the intake end of the intake pipe (41) is used to connect to an external gas source, and the outlet end of the intake pipe (41) is in communication with the cavity.

5. The water removal and CO2 removal device according to claim 3, characterized in that: The air inlet pipe (41) is provided with a control valve (42) for controlling the on-off of the drying gas and a flow valve (43) for adjusting the pressure difference between the inner and outer pipes.

6. The water removal and CO2 removal device according to claim 3, characterized in that: The exhaust assembly (5) comprises an exhaust pipe communicated with the cavity.

7. The water removal and CO2 removal device according to any one of claims 1 to 6, characterized in that: The CO2 adsorption tube comprises a tube body (21) for filling an adsorbent, the tube body (21) being arranged in a vertical direction, and straight-through joints (22) being provided at both ends of the tube body (21), the straight-through joints (22) being connected to the tube body (21) via locking nuts (23).

8. The water removal and CO2 removal device according to any one of claims 1 to 6, characterized in that: A heating component (6) is provided around the sample delivery pipeline (1), the Nafion drying tube, and the CO2 adsorption tube.

9. A volatile organic compound detection system, characterized in that: It comprises an automatic sample injector (100), a pre-concentration device (101) and a detector (102), wherein a water removal and CO2 removal device as claimed in any one of claims 1 to 8 is arranged between the automatic sample injector (100) and the pre-concentration device (101).

10. The volatile organic compound detection system according to claim 9, characterized in that: The detector (102) is a GCMS detector or a GC-FID detector.

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