A VOCs component detection system

Abstract

The application belongs to the technical field of VOCs detection, and particularly relates to a VOCs component detection system. Sample gas enters an enrichment unit from a sample gas port for enrichment; first carrier gas passes through the enrichment unit after a four-way valve, washes out the gas adsorbed in the enrichment unit, flows into a separation assembly for separation, and then enters a PID detector for detection analysis; after analysis, the carrier gas carrying atomized water and dry carrier gas are used for reverse blowing in sequence, and then the next round of test can be performed. The application adopts a low-heat-capacity chromatographic column and a high-sensitivity PID detector, effectively reduces the volume and energy consumption of the device through EPC control, and effectively improves the applicability of using a portable device to detect a wide spectrum of VOCs; humidification reverse blowing and dry sweeping are set, low-boiling-point species, oxygen-containing VOCs and nitrogen-containing VOCs that are difficult to remove in the traditional way can be effectively removed through humidification reverse blowing, background interference is reduced, and the VOCs detection effect is effectively improved.

Description

Technical Field

[0001] This application belongs to the field of VOCs detection technology, and in particular relates to a VOCs component detection system. Background Technology

[0002] Volatile organic compounds (VOCs) are an important trace component of ambient air, encompassing a variety of important air pollutants, involving complex chemical structures, and presenting very low concentrations in the atmosphere. Therefore, accurate detection of VOC components presents significant technical challenges. Furthermore, due to the complex sources of atmospheric VOCs, with substantial differences in concentration, composition, and origin at different locations, traditional large-scale equipment is bulky and often insufficient for comprehensive coverage. Miniaturized VOC component detection technologies are therefore crucial for current air pollution control, environmental quality improvement, and socio-economic development.

[0003] Existing miniaturized VOCs monitoring equipment primarily focuses on monitoring total VOCs, limiting its application in detecting broad-spectrum VOCs. On one hand, miniaturization is constrained by size and weight requirements, necessitating sophisticated structural design and component selection. On the other hand, miniaturized devices often face challenges such as low detection limits, excessive background interference, and insufficient detection accuracy, resulting in a limited range of detectable components (detecting only a few species, difficulty in detecting low concentrations of species, and susceptibility to interference). Common low-boiling-point species, oxygen-containing VOCs, and nitrogen-containing VOCs in ambient air are easily adsorbed and difficult to remove from common stainless steel, PTFE, and PEEK piping equipment, leaving monitoring residues and causing excessive background noise, thus hindering effective identification and analysis of VOC components.

[0004] Photoionization detectors (PIDs) utilize high-energy ultraviolet light to ionize gas molecules and generate current signals. PIDs typically use ultraviolet light sources, which have a much longer lifetime than PIDs with other ionization energy levels, and can identify a wide range of VOC components. They are highly sensitive to various VOC components such as alkenes, benzene compounds, aldehydes, ketones, and long-chain alkanes, making them suitable for portable VOC detection. However, relying solely on PIDs suffers from low selectivity. This application innovatively combines PID with separation technology to achieve effective detection of a broad spectrum of VOCs. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this application provides a VOCs component detection system that can reduce background interference and improve detection results.

[0006] To achieve the above objectives, the technical solution provided in this application is as follows:

[0007] This application provides a VOCs component detection system, including:

[0008] A twelve-way valve, comprising twelve valve ports, namely the first valve port, the second valve port, the third valve port, the fourth valve port, the fifth valve port, the sixth valve port, the seventh valve port, the eighth valve port, the ninth valve port, the tenth valve port, the eleventh valve port, and the twelfth valve port;

[0009] The sample gas inlet is connected to the second valve port of a twelve-way valve via a pipeline, and is used for the entry of sample gas and the discharge of waste gas.

[0010] The enrichment unit is used to adsorb VOCs components in the sample gas. One end of the enrichment unit is connected to the first valve port of the twelve-way valve, and the other end of the enrichment unit is equipped with a three-way valve. One end of the other two ends of the three-way valve is connected to an air pump, and the other end is connected to the fourth valve port of the twelve-way valve through a pipeline.

[0011] The first carrier gas inlet pipeline is used to provide the first carrier gas for analysis and testing, and is connected to the fifth valve port of the twelve-way valve through a four-way valve;

[0012] The separation component is used to separate the VOCs components absorbed by the enrichment unit. The inlet end of the separation component is connected to the twelfth valve port of the twelve-way valve, and the outlet end of the separation component is connected to the eighth valve port of the twelve-way valve.

[0013] The PID detector is used to analyze the concentration of VOCs components in the air. The inlet of the PID detector is connected to the ninth valve port of the twelve-way valve.

[0014] The humidifying backflush unit is used to provide the backflush with atomized water carrier gas and dry carrier gas and to control the switching of the backflush carrier gas between the atomized water carrier gas and the dry carrier gas. The humidifying backflush unit is connected to the seventh valve port of the twelve-way valve and is connected to the third valve port of the twelve-way valve through the four-way valve.

[0015] The sixth port of the twelve-way valve is connected to the tenth port of the twelve-way valve via a pipeline, and the eleventh port of the twelve-way valve is connected to a waste gas discharge pipeline.

[0016] Optionally, the humidification backflushing unit includes a second carrier gas inlet pipe and an atomizing water pipe. The second carrier gas inlet pipe and the atomizing water pipe are mixed in a certain proportion through a second flow control valve and then connected to the seventh valve port of the twelve-way valve and the four-way valve.

[0017] Optionally, the second flow control valve employs EPC flow control.

[0018] Optionally, a first flow control valve is provided between the seventh port of the four-way valve and the twelve-way valve.

[0019] Optionally, the separation component includes a low-heat-capacity chromatographic column.

[0020] Optionally, the enrichment unit includes an enrichment tube filled with carbon black and carbon molecular sieve.

[0021] Optionally, when in the injection state, the first valve port of the twelve-way valve is connected to the second valve port, the third valve port is connected to the fourth valve port, the fifth valve port is connected to the sixth valve port, the seventh valve port is connected to the eighth valve port, the ninth valve port is connected to the tenth valve port, and the eleventh valve port is connected to the twelfth valve port.

[0022] When in analysis mode, the first valve port of the twelve-way valve is connected to the twelfth valve port, the second valve port is connected to the third valve port, the fourth valve port is connected to the fifth valve port, the sixth valve port is connected to the seventh valve port, the eighth valve port is connected to the ninth valve port, and the tenth valve port is connected to the eleventh valve port.

[0023] Optionally, the carrier gas in the first carrier gas inlet pipeline and the second carrier gas inlet pipeline includes one or more of nitrogen and helium.

[0024] Compared with the prior art, this application has at least the following beneficial effects:

[0025] This application employs a humidified backflushing and a dry sweep-flushing method. Humidified backflushing effectively removes low-boiling-point species, oxygen-containing VOCs, and nitrogen-containing VOCs that are traditionally difficult to remove, reducing background interference. Subsequent dry carrier gas backflushing removes moisture, preventing humidity from affecting the detection results. This effectively improves VOCs detection performance, enhances the accuracy and identification range of VOCs detection, and enables precise monitoring of a broad spectrum of VOCs components.

[0026] Employing a low-heat-capacity chromatographic column and a high-sensitivity PID detector, and using EPC control, the device's size (the entire unit weighs no more than 15 kg) and energy consumption are effectively reduced, significantly improving the applicability of portable devices for detecting broad-spectrum VOCs. Through EPC flow control, the pressure in the fluid system is controlled by the intensity of the electrical signal, enabling precise flow control and improving the repeatability and accuracy of qualitative and quantitative measurements. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a system state diagram of a VOCs component detection system in the sample injection state according to an embodiment of this application;

[0029] Figure 2 This is a system state diagram of a VOCs component detection system in the analysis state according to an embodiment of this application;

[0030] Figure 3 This is a system state diagram of a VOCs component detection system in the backflushing state according to an embodiment of this application;

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. First valve port; 2. Second valve port; 3. Third valve port; 4. Fourth valve port; 5. Fifth valve port; 6. Sixth valve port; 7. Seventh valve port; 8. Eighth valve port; 9. Ninth valve port; 10. Tenth valve port; 11. Eleventh valve port; 12. Twelfth valve port; 20. Twelfth-way valve; 21. Sample gas port; 22. Enrichment tube; 23. Three-way valve; 24. Gas pump; 25. First carrier gas inlet line; 26. Four-way valve; 27. Low heat capacity chromatographic column; 28. PID detector; 29. ​​Second carrier gas inlet line; 30. Nebulized water line; 31. Second flow control valve; 32. Exhaust gas discharge line; 33. First flow control valve. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use.

[0034] Example 1

[0035] like Figure 1 As shown, a VOCs component detection system includes:

[0036] The twelve-way valve 20 includes twelve valve ports, namely, first valve port 1, second valve port 2, third valve port 3, fourth valve port 4, fifth valve port 5, sixth valve port 6, seventh valve port 7, eighth valve port 8, ninth valve port 9, tenth valve port 10, eleventh valve port 11, and twelfth valve port 12.

[0037] Sample gas port 21 is connected to the second valve port 2 of the twelve-way valve 20 via a pipeline, and is used for the entry of sample gas and the discharge of waste gas.

[0038] The enrichment unit is used to adsorb VOCs components in the sample gas. One end of the enrichment unit is connected to the first valve port 1 of the twelve-way valve 20, and the other end of the enrichment unit is provided with a three-way valve 23. One end of the other two ends of the three-way valve 23 is connected to a gas pump 24, and the other end is connected to the fourth valve port 4 of the twelve-way valve 20 through a pipeline.

[0039] The first carrier gas inlet pipeline 25 is used to provide the first carrier gas for analysis and testing. In this embodiment, the first carrier gas is nitrogen, but it can also be other inert gases such as helium. It is connected to the fifth valve port 5 of the twelve-way valve 20 through the four-way valve 26.

[0040] The separation component is used to separate the VOCs components absorbed by the enrichment unit. The inlet end of the separation component is connected to the twelfth valve port 12 of the twelve-way valve 20, and the outlet end of the separation component is connected to the eighth valve port 8 of the twelve-way valve 20.

[0041] The PID detector 28 is used to analyze the concentration of VOCs components in the air. The inlet of the PID detector 28 is connected to the ninth valve port 9 of the twelve-way valve 20.

[0042] The humidifying backflush unit is used to provide the backflush with atomized water-carrying carrier gas and the dry carrier gas, and to control the switching of the backflush carrier gas between the atomized water-carrying carrier gas and the dry carrier gas. The humidifying backflush unit is connected to the seventh valve port 7 of the twelve-way valve 20, and is connected to the third valve port 3 of the twelve-way valve 20 through the four-way valve 26.

[0043] Humidified backflushing effectively removes low-boiling-point species, oxygen-containing VOCs, and nitrogen-containing VOCs that are traditionally difficult to remove, reducing background interference. Subsequent backflushing with a dry carrier gas removes moisture, preventing humidity from affecting the detection results. This effectively improves VOCs detection performance, enhances the accuracy and identification range of VOCs detection, and enables precise monitoring of a broad spectrum of VOCs components.

[0044] Example 2

[0045] The difference between this embodiment and Embodiment 1 is that the humidification backflushing unit includes a second carrier gas inlet pipe 29 and an atomizing water pipe 30. The second carrier gas inlet pipe 29 and the atomizing water pipe 30 are mixed in a certain proportion through a second flow control valve 31 and then connected to the seventh valve port 7 of the twelve-way valve 20 and the four-way valve 26. The second carrier gas is generally nitrogen or argon. The mixing ratio of the second carrier gas inlet pipe 29 and the atomizing water pipe 30 can be controlled by the second flow control valve 31. When the flow rate of the atomizing water pipe 30 is controlled to be 0, a dry carrier gas can be provided. In this embodiment, the atomizing water pipe 30 is supplied with atomized water vapor by an atomizing humidifier.

[0046] The sixth valve port 6 of the twelve-way valve 20 is connected to the tenth valve port 10 of the twelve-way valve 20 through a pipeline, and the eleventh valve port 11 of the twelve-way valve 20 is connected to the exhaust gas discharge pipeline 32.

[0047] When in the injection state, the first valve port 1 of the twelve-way valve 20 is connected to the second valve port 2, the third valve port 3 is connected to the fourth valve port 4, the fifth valve port 5 is connected to the sixth valve port 6, the seventh valve port 7 is connected to the eighth valve port 8, the ninth valve port 9 is connected to the tenth valve port 10, and the eleventh valve port 11 is connected to the twelfth valve port 12.

[0048] When in analysis mode, the first valve port 1 of the twelve-way valve 20 is connected to the twelfth valve port 12, the second valve port 2 is connected to the third valve port 3, the fourth valve port 4 is connected to the fifth valve port 5, the sixth valve port 6 is connected to the seventh valve port 7, the eighth valve port 8 is connected to the ninth valve port 9, and the tenth valve port 10 is connected to the eleventh valve port 11.

[0049] In this embodiment, a first flow control valve 33 is provided between the four-way valve 26 and the seventh valve port 7 of the twelve-way valve 20. The flow rate of the carrier gas can be adjusted by the first flow control valve 33.

[0050] In this embodiment, both the first flow control valve and the second flow control valve adopt EPC flow control.

[0051] In this embodiment, the separation component includes a low heat capacity chromatographic column 27. After separation by the low heat capacity chromatographic column 27, the components are then detected by the PID detector 28, which can simultaneously identify multiple VOCs components and avoid the drawback of poor selectivity of the PID detector 28 alone.

[0052] The enrichment unit includes an enrichment tube 22, which is filled with carbon black and carbon molecular sieves, and absorbs VOC components through the carbon black and carbon molecular sieves.

[0053] The use of a low-heat-capacity chromatographic column 27 in conjunction with a PID detector 28 improves detection accuracy. This application also incorporates humidified backflushing and dry sweep-flushing. Humidified backflushing effectively removes traditionally difficult-to-remove low-boiling-point species, oxygen-containing VOCs, and nitrogen-containing VOCs, reducing background interference. Subsequent dry carrier gas backflushing removes moisture, preventing humidity from affecting the detection results. This effectively improves VOCs detection performance, enhances the accuracy and identification range of VOCs detection, and enables precise monitoring of a broad spectrum of VOCs components.

[0054] A method for detecting VOCs components, based on the VOCs component detection system described in Example 1, includes:

[0055] S1: Injection

[0056] Switch the 12-way valve 20 to the sample injection state, that is, the first valve port 1 of the 12-way valve 20 is connected to the 12th valve port 12, the second valve port 2 is connected to the third valve port 3, the fourth valve port 4 is connected to the fifth valve port 5, the sixth valve port 6 is connected to the seventh valve port 7, the eighth valve port 8 is connected to the ninth valve port 9, and the tenth valve port 10 is connected to the eleventh valve port 11; switch the 3-way valve 23 to connect the enrichment tube 22 to the gas pump 24;

[0057] The sample gas is drawn by the air pump 24 and enters through the sample gas port 21. Then it passes through the second valve port 2 and the first valve port 1 of the twelve-way valve 20 in sequence before entering the enrichment unit for enrichment.

[0058] At the same time, the four-way valve 26 is switched to connect the first carrier gas inlet pipeline 25 with the fifth valve port 5 of the twelve-way valve 20; the first carrier gas passes through the four-way valve 26 and then through the fifth valve port 5, the sixth valve port 6, the tenth valve port 10 and the ninth valve port 9 of the twelve-way valve 20 before entering the PID detector 28, thereby stabilizing the intake of the PID detector 28 when entering S2. Figure 1 This is a system state diagram during sample introduction.

[0059] S2: Analysis

[0060] Switch the 12-way valve 20 to the analysis state, that is, the first valve port 1 of the 12-way valve 20 is connected to the 12th valve port 12, the second valve port 2 is connected to the third valve port 3, the fourth valve port 4 is connected to the fifth valve port 5, the sixth valve port 6 is connected to the seventh valve port 7, the eighth valve port 8 is connected to the ninth valve port 9, and the tenth valve port 10 is connected to the eleventh valve port 11; switch the 3-way valve 23 to the enrichment pipe 22 and connect it to the fourth valve port 4 of the 12-way valve 20, and switch the 4-way valve 26 to the first carrier gas inlet pipe 25 and connect it to the fifth valve port 5 of the 12-way valve 20;

[0061] Nitrogen gas enters through the first carrier gas inlet pipe 25 and the four-way valve 26, and then passes through the fifth valve port 5, the fourth valve port 4 and the three-way valve 23 of the twelve-way valve 20 in sequence before passing through the enrichment unit to elute the gas adsorbed in the enrichment tube 22. After that, the gas flows into the low heat capacity chromatographic column 27 through the first valve port 1 and the twelfth valve port 12 of the twelve-way valve 20 for separation. The separated components flow out through the eighth valve port 8 and the ninth valve port 9 of the twelve-way valve 20 and enter the PID detector 28 for detection and analysis, and qualitative and quantitative detection of the sample. Figure 2 This is a system state diagram for analysis.

[0062] S3: Backflush

[0063] Switch the 12-way valve 20 to the sample injection state, switch the 3-way valve 23 to connect the enrichment tube 22 to the fourth valve port 4 of the 12-way valve 20, and switch the 4-way valve 26 to connect the humidification backflush unit to the third valve port 3 of the 12-way valve 20.

[0064] After the flow rate of the atomized water pipeline 30 and the second carrier gas inlet pipeline 29 is regulated by the second flow control valve 31, a carrier gas carrying atomized water is obtained. The carrier gas carrying atomized water passes through the three-way valve 23 and then sequentially through the fourth valve port 4, the third valve port 3, the three-way valve 23, the enrichment unit, and the first valve port 1 and the second valve port 2 of the twelve-way valve 20 before being discharged through the sample gas port 21. On the other hand, the carrier gas carrying atomized water passes through the seventh valve port 7 and the eighth valve port 8 of the twelve-way valve 20 and then enters the separation unit. After passing through the twelfth valve port 12 and the eleventh valve port 11 of the twelve-way valve 20, it is discharged through the waste gas discharge pipeline 32.

[0065] Then, control the second flow control valve 31 to switch the carrier gas to dry carrier gas and perform drying backflushing. Figure 3 This is a system state diagram during the backflush process.

[0066] This application effectively removes low-boiling-point species, oxygen-containing VOCs, and nitrogen-containing VOCs that are traditionally difficult to remove by humidification backflushing, reducing background interference and lowering the minimum detection limit; further backflushing with a dry carrier gas removes moisture, avoiding the influence of humidity on the detection results and effectively improving the VOCs detection effect.

[0067] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0068] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A VOCs component detection system, characterized in that, include: A twelve-way valve, comprising twelve valve ports, namely the first valve port, the second valve port, the third valve port, the fourth valve port, the fifth valve port, the sixth valve port, the seventh valve port, the eighth valve port, the ninth valve port, the tenth valve port, the eleventh valve port, and the twelfth valve port; The sample gas inlet is connected to the second valve port of a twelve-way valve via a pipeline, and is used for the entry of sample gas and the discharge of waste gas. The enrichment unit is used to adsorb VOCs components in the sample gas. One end of the enrichment unit is connected to the first valve port of the twelve-way valve, and the other end of the enrichment unit is equipped with a three-way valve. One end of the other two ends of the three-way valve is connected to an air pump, and the other end is connected to the fourth valve port of the twelve-way valve through a pipeline. The first carrier gas inlet pipeline is used to provide the first carrier gas for analysis and testing, and is connected to the fifth valve port of the twelve-way valve through a four-way valve; The separation component is used to separate the VOCs components absorbed by the enrichment unit. The inlet end of the separation component is connected to the twelfth valve port of the twelve-way valve, and the outlet end of the separation component is connected to the eighth valve port of the twelve-way valve. The PID detector is used to analyze the concentration of VOCs components in the air. The inlet of the PID detector is connected to the ninth valve port of the twelve-way valve. The humidifying backflush unit is used to provide the backflush with atomized water carrier gas and dry carrier gas and to control the switching of the backflush carrier gas between the atomized water carrier gas and the dry carrier gas. The humidifying backflush unit is connected to the seventh valve port of the twelve-way valve and is connected to the third valve port of the twelve-way valve through the four-way valve. The sixth port of the twelve-way valve is connected to the tenth port of the twelve-way valve via a pipeline, and the eleventh port of the twelve-way valve is connected to a waste gas discharge pipeline.

2. The VOCs component detection system according to claim 1, characterized in that, The humidification backflushing unit includes a second carrier gas inlet pipe and an atomizing water pipe. The second carrier gas inlet pipe and the atomizing water pipe are mixed in a certain proportion through a second flow control valve and then connected to the seventh valve port of the twelve-way valve and the four-way valve.

3. The VOCs component detection system according to claim 2, characterized in that, The second flow control valve uses EPC flow control.

4. The VOCs component detection system according to claim 1, characterized in that, A first flow control valve is provided between the seventh port of the four-way valve and the twelve-way valve.

5. The VOCs component detection system according to claim 1, characterized in that, The separation component includes a low-heat-capacity chromatographic column.

6. The VOCs component detection system according to claim 1, characterized in that, The enrichment unit includes an enrichment tube filled with carbon black and carbon molecular sieve.

7. The VOCs component detection system according to claim 1, characterized in that, When in the sample injection state, the first valve port of the twelve-way valve is connected to the second valve port, the third valve port is connected to the fourth valve port, the fifth valve port is connected to the sixth valve port, the seventh valve port is connected to the eighth valve port, the ninth valve port is connected to the tenth valve port, and the eleventh valve port is connected to the twelfth valve port. When in analysis mode, the first valve port of the twelve-way valve is connected to the twelfth valve port, the second valve port is connected to the third valve port, the fourth valve port is connected to the fifth valve port, the sixth valve port is connected to the seventh valve port, the eighth valve port is connected to the ninth valve port, and the tenth valve port is connected to the eleventh valve port.

8. The VOCs component detection system according to claim 1, characterized in that, The carrier gas in the first carrier gas inlet pipeline and the second carrier gas inlet pipeline includes one or more of nitrogen and helium.

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