Particle state pretreatment device and multi-medium VOCs (Volatile Organic Compounds) online monitoring system

Abstract

The utility model belongs to the technical field of VOCs monitoring and detection. The utility model provides a particle state pretreatment device. The particle state pretreatment device comprises an upper part, a lower part, an annular sealing ring, a quartz filter membrane and a stainless steel filter membrane net support, the upper part comprises a first port and a second port; the first port is formed in the center of the top end of the upper part; the second port is formed in the side wall of the upper part and is close to the top end; the lower part comprises a third port and a groove buckle; the third port is formed in the center of the bottom end of the lower part; the groove buckle is arranged on the inner side of the top end of the lower part; the stainless steel filter membrane net support is placed in the groove, the quartz filter membrane is placed on the stainless steel filter membrane net support, and the annular sealing gasket is placed on the quartz filter membrane and used for sealing the connecting position of the upper portion and the lower portion. According to the device provided by the utility model, on the basis of separating a dissolved state from a particle state, the actual concentration of the VOCs in water can be really reflected by monitoring data, and the problem of lack of the particle VOCs in an existing online method is avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of VOCs monitoring and detection. Background Art

[0002] The monitoring of VOCs in water is of great significance for environmental protection, human health and ecological research. However, existing monitoring methods often cannot comprehensively and accurately monitor VOCs in water samples.

[0003] The laboratory method is to separate the particulate matter in the water from the water sample through a filter membrane, dry the filter membrane with a freeze dryer and then weigh it, perform Soxhlet extraction with an organic reagent, concentrate and enrich the liquid with a rotary evaporator, and then use LCMS or GCMS after vaporization for detection; after the water sample is separated, it is subjected to solid phase extraction, organic reagent elution, and rotary evaporation concentration and enrichment, and then also detected by LCMS or GCMS.

[0004] Methods such as online purge and trap + thermal analysis + GC / GCMS are to pass a constant flow rate of inert gas through the sample for a fixed time, purge the VOCs in the sample into the headspace above the sample and transfer it to a trap containing an adsorbent, then heat and back-blow the adsorbent with a carrier gas, and transfer the analyzed sample to the back-end detection equipment for measurement.

[0005] Methods such as membrane separation + SPI mass spectrometer use semi-permeable membranes such as PDMS to separate VOCs from water by virtue of the osmotic pressure difference on both sides of the membrane, and then transmit the VOCs components through carrier gas to an online mass spectrometer such as a SPI mass spectrometer for analysis.

[0006] VOCs in water are usually composed of dissolved and particulate states. In laboratory methods, dissolved and particulate VOCs are extracted by separation and pretreatment, and then introduced into the detection system. However, laboratory methods are basically processed manually, and the operation of the method is cumbersome and complicated, and it is difficult to ensure the consistency and repeatability of different personnel in the experiment. In the past, online methods usually used headspace, adsorption analysis or semi-permeable membrane penetration to extract VOCs from water and send them to the instrument to be tested for analysis. The above methods only extract and detect dissolved VOCs in water, and cannot accurately represent the actual concentration of VOCs in water. Utility Model Content

[0007] In view of this, the utility model provides a particle pretreatment device, including: an upper part, a lower part, an annular sealing ring, a quartz filter membrane and a stainless steel filter membrane net support; the upper part includes a first port and a second port; the first port is arranged at the center position of the top end of the upper part; the second port is arranged on the side wall of the upper part and close to the top end; the lower part includes a third port and a groove buckle; the third port is arranged at the center position of the bottom end of the lower part; the groove buckle is arranged on the inner side of the top end of the lower part; the stainless steel filter membrane net support is placed in the groove, the quartz filter membrane is placed on the stainless steel filter membrane net support, and the annular sealing gasket is placed on the quartz filter membrane and is used for sealing at the connection between the upper and lower parts.

[0008] In a specific embodiment of the present invention, the upper part and the lower part are made of quartz glass or stainless steel, and the outer sides thereof are wrapped with heating wires or heating belts.

[0009] The utility model also provides a multi-media VOCs online monitoring system, including: a first injection pump, a second injection pump, a first particle state pretreatment device, a second particle state pretreatment device, a dissolved state pretreatment device, a first electromagnetic three-way valve, a second electromagnetic three-way valve, a third electromagnetic three-way valve, a fourth electromagnetic three-way valve, a fifth electromagnetic three-way valve, an electromagnetic four-way valve, and a detection system; the first injection pump is connected to the first port of the first particle state pretreatment device; the second injection pump is connected to the first port of the second particle state pretreatment device; the second port of the first particle state pretreatment device is connected to the second port of the fourth electromagnetic three-way valve; the third port of the first particle state pretreatment device is connected to the first port of the first electromagnetic three-way valve; the second port of the second particle state pretreatment device is connected to the third port of the fourth electromagnetic three-way valve; the third port of the second particle state pretreatment device is connected to the first port of the first electromagnetic three-way valve; It is connected with the first port of the second electromagnetic three-way valve; the second port of the first electromagnetic three-way valve is connected with the third port of the third electromagnetic three-way valve, and the third port of the first electromagnetic three-way valve is connected with the second port of the electromagnetic four-way valve; the second port of the second electromagnetic three-way valve is connected with the first port of the third electromagnetic three-way valve, and the third port of the second electromagnetic three-way valve is connected with the fourth port of the electromagnetic four-way valve; the first port of the third electromagnetic three-way valve is connected with the second port of the dissolved state pre-treatment device; the first port of the fourth electromagnetic three-way valve is connected with the third port of the fifth electromagnetic three-way valve; the first port of the fifth electromagnetic three-way valve is connected with the detection system, and the second port of the fifth electromagnetic three-way valve is connected with the first port of the dissolved state pre-treatment device; the first port of the electromagnetic four-way valve is connected with high-purity nitrogen, and the third port of the electromagnetic four-way valve is used for emptying.

[0010] In a specific embodiment of the present invention, the detection system is PTR-TOF MS.

[0011] In the utility model, on the basis of separating the dissolved and particulate states, the extracted VOCs are introduced into the PTR-TOF MS for detection through online pretreatment. On the one hand, it avoids the time-consuming and labor-intensive laboratory method and the problem of poor consistency. On the other hand, it also realizes the online monitoring of dissolved and particulate VOCs by the same system, ensuring that the monitoring data can truly reflect the actual concentration of VOCs in water and avoiding the problem of missing particulate VOCs in existing online methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of the system for detecting VOCs components in samples using PTR-TOF.

[0013] Figure 2 This is a system flow chart for monitoring dissolved VOCs in water samples (channel 1).

[0014] Figure 3 This is a system flow chart for monitoring particulate VOCs in water samples (channel 2).

[0015] Figure 4 This is a system flow chart for monitoring dissolved VOCs in water samples (channel 2).

[0016] Figure 5 This is a system flow chart for monitoring particulate VOCs in water samples (channel 1).

[0017] Figure 6 It is a schematic diagram of the structure of a particle pretreatment device.

[0018] Among them, 1 is the first port, 2 is the second port, 3 is the third port, 4 is the stainless steel membrane net support, 5 is the quartz filter membrane, 6 is the annular sealing gasket, 7 is the upper part, and 8 is the lower part. DETAILED DESCRIPTION

[0019] VOCs: Volatile Organic Compounds

[0020] PTR-TOF MS: Proton Transfer Reaction Time-of-Flight Mass Spectrometry

[0021] Example

[0022] In view of the above situation, in the utility model, on the basis of separating the dissolved and particulate states, the extracted VOCs are introduced into the PTR-TOF MS for detection through online pretreatment. On the one hand, it avoids the time-consuming, labor-intensive and poor consistency problems of laboratory methods. On the other hand, it also realizes the online monitoring of dissolved and particulate VOCs by the same system, ensuring that the monitoring data can truly reflect the actual concentration of VOCs in water and avoiding the problem of missing particulate VOCs in existing online methods.

[0023] The PTR-TOF used in the utility model can quickly monitor atmospheric samples, and the ion source of the PTR-TOF ionizes the wet air through glow discharge to generate H3O + 、O2 + 、NO + Chemical reagent ions such as ions have a good analytical effect on common VOCs in water. Although the water in the gaseous VOCs sample converted during the pretreatment process will produce some multi-hydrated proton clusters after dilution with dry high-purity nitrogen, it will not have much impact on the detection performance and instrument life of PTR-TOF, and will be discharged under the action of the vacuum pump. With the help of the extremely high sensitivity of PTR-TOF, the detection effect of VOCs in water after pretreatment extraction is guaranteed.

[0024] In this utility model, PTR-TOF is used to detect VOCs components in samples. The system principle is as follows Figure 1 The multi-media VOCs online monitoring system provided by the utility model includes: a first injection pump, a second injection pump, a first particle state pretreatment device, a second particle state pretreatment device, a dissolved state pretreatment device, a first electromagnetic three-way valve, a second electromagnetic three-way valve, a third electromagnetic three-way valve, a fourth electromagnetic three-way valve, a fifth electromagnetic three-way valve, an electromagnetic four-way valve, and a detection system.

[0025] The detection system is preferably PTR-TOF MS.

[0026] The first injection pump and the second injection pump are used for collecting and inputting water samples; the first injection pump is connected to the first port of the first particle state pretreatment device; the second injection pump is connected to the first port of the second particle state pretreatment device.

[0027] The schematic diagram of the particle pre-treatment device is as follows: Figure 6As shown, the main body consists of two parts, the upper part and the lower part, with an internal diameter of 5cm, a wall thickness of 2mm, and a length of 4cm for both the upper and lower parts. It is made of stainless steel or quartz glass. The contact surfaces of the upper and lower parts have a threaded structure for easy disassembly and tightening. The stainless steel filter membrane net holder is placed in the groove on the inner side of the top of the lower part, on which a quartz filter membrane can be placed to filter the particles in the sample. An annular sealing gasket (composed of high-temperature resistant rubber with an outer membrane of aluminum foil material) is placed on the quartz filter membrane. When the upper and lower parts of the main body are tightened, the sealing gasket is pressed to deform it, thereby achieving a sealing effect at the connection between the upper and lower parts. The first port is located at the center of the top of the upper part, the second port is located on the side wall of the upper part and close to the top, and the third port is located at the center of the bottom of the lower part. The port size is set according to actual needs, and is generally matched with the commonly used pipeline size (such as an outer diameter of 6mm, etc.). After the particulate matter pretreatment device is installed, the outer sides of the upper and lower parts are wrapped with heating wires or heating belts to heat them at high temperatures to release the VOCs components in the particle state.

[0028] The first particle state pretreatment device and the second particle state pretreatment device are used to filter the collected water samples, separate the particle state and dissolved VOCs, and have the function of extracting particle state VOCs. The second port of the first particle state pretreatment device is connected to the second port of the fourth electromagnetic three-way valve; the third port of the first particle state pretreatment device is connected to the first port of the first electromagnetic three-way valve. The second port of the second particle state pretreatment device is connected to the third port of the fourth electromagnetic three-way valve; the third port of the second particle state pretreatment device is connected to the first port of the second electromagnetic three-way valve. The particle state pretreatment device is used to filter the particle components in the water sample, and can ensure that after the particle components are filtered, the VOCs in the particle components are released through thermal analysis and introduced into the detection system by high-purity nitrogen.

[0029] The first port of the first electromagnetic three-way valve is connected to the third port of the first particle pretreatment device, the second port of the first electromagnetic three-way valve is connected to the third port of the third electromagnetic three-way valve, and the third port of the first electromagnetic three-way valve is connected to the second port of the electromagnetic four-way valve.

[0030] The first port of the second electromagnetic three-way valve is connected to the third port of the second particle pretreatment device, the second port of the second electromagnetic three-way valve is connected to the second port of the third electromagnetic three-way valve, and the third port of the second electromagnetic three-way valve is connected to the fourth port of the electromagnetic four-way valve.

[0031] The first port of the third electromagnetic three-way valve is connected to the second port of the dissolved state pretreatment device, the second port of the third electromagnetic three-way valve is connected to the first port of the second electromagnetic three-way valve, and the third port of the third electromagnetic three-way valve is connected to the first port of the second electromagnetic three-way valve.

[0032] The first port of the fourth electromagnetic three-way valve is connected to the third port of the fifth electromagnetic three-way valve, the second port of the fourth electromagnetic three-way valve is connected to the second port of the first particle state pretreatment device, and the third port of the fourth electromagnetic three-way valve is connected to the second port of the second particle state pretreatment device.

[0033] The first port of the fifth electromagnetic three-way valve is connected to the detection system, the second port of the fifth electromagnetic three-way valve is connected to the first port of the dissolved state pre-treatment device, and the third port of the fifth electromagnetic three-way valve is connected to the first port of the fourth electromagnetic three-way valve. The detection system is preferably PTR-TOF MS.

[0034] The electromagnetic four-way valve is used to achieve switching of different flow paths and detection of VOCs by switching the electromagnetic valve combination; the first port of the electromagnetic four-way valve is connected to high-purity nitrogen, the second port of the electromagnetic four-way valve is connected to the third port of the first electromagnetic three-way valve, the third port of the electromagnetic four-way valve is used for emptying, and the fourth port of the electromagnetic four-way valve is connected to the third port of the second electromagnetic three-way valve.

[0035] The dissolved state pretreatment device is used to extract the VOCs dissolved in the water sample; the first port of the dissolved state pretreatment device is connected to the second port of the fifth electromagnetic three-way valve, and the second port of the dissolved state pretreatment device is connected to the first port of the third electromagnetic three-way valve. The dissolved state pretreatment device is subjected to thermal analysis after atomization to be transformed into a gaseous state, and the gaseous components are introduced into the PTR-TOF MS for detection due to the negative pressure of the PTR-TOF MS.

[0036] The high-purity nitrogen is used to introduce particulate VOCs into PTR-TOF MS for detection, and the high-purity nitrogen is connected to the first port of the electromagnetic four-way valve.

[0037] The detection system is preferably a PTR-TOF MS, which is a highly sensitive VOCs detection instrument used for the detection performance of dissolved and particulate VOCs; the PTR-TOF MS is connected to the first port of the fifth electromagnetic three-way valve.

[0038] The monitoring method of the multi-media VOCs online monitoring system is divided into four steps and repeated in a cycle to achieve online monitoring of dissolved and particulate VOCs in water samples.

[0039] Step 1: Monitoring of first dissolved VOCs in water samples (channel 1)

[0040] The system flow diagram of step one is as follows Figure 2 As shown, this step is the monitoring of dissolved VOCs in the water sample (channel 1), specifically: the first port and the second port of the first solenoid three-way valve are connected, the first port and the third port of the third solenoid three-way valve are connected, the first port and the second port of the fifth solenoid three-way valve are connected, the first port and the third port of the second solenoid three-way valve are connected, the third port and the fourth port of the solenoid four-way valve are connected, and the first port and the second port are connected; the first port and the second port of the fourth solenoid three-way valve are connected.

[0041] The first injection pump is activated to pass the quantitative water sample into the first particle pretreatment device for filtration. The filtered water sample enters the dissolved state pretreatment device through the first electromagnetic three-way valve and the third electromagnetic three-way valve, and enters the detection system PTR-TOF MS through the fifth electromagnetic three-way valve after vaporization; the second particle pretreatment device is in an emptying state, which can ensure that the residual water on the filter membrane and in the pipeline after filtration can be discharged to the outside, reducing the high-purity nitrogen gas from back-flushing the residual water into the detection system after thermal analysis in the subsequent steps.

[0042] (2) Step 2: Monitoring of first particle-phase VOCs in water samples (Channel 2)

[0043] The system flow diagram of step 2 is as follows Figure 3 As shown, this step is the monitoring of particulate VOCs in the water sample (channel 2), specifically: the first port and the third port of the first solenoid three-way valve are connected, the first port and the third port of the second solenoid three-way valve are connected, the second port and the third port of the solenoid four-way valve are connected, the first port and the fourth port are connected, the first port and the third port of the fourth solenoid three-way valve are connected, the first port and the third port of the fifth solenoid three-way valve are connected; the first port and the third port of the third solenoid three-way valve are connected.

[0044] The first injection pump stops, and the residual water in the first particle pretreatment and in the pipeline is drained through the first electromagnetic three-way valve and the four-way electromagnetic valve. The second particle pretreatment device performs thermal analysis, and high-purity nitrogen passes through the four-way solenoid valve, the second electromagnetic three-way valve and the second particle pretreatment device in sequence. The analyzed VOCs are introduced into the PTR-TOF MS through the fourth electromagnetic three-way valve and the fifth electromagnetic three-way valve for detection.

[0045] (3) Step 3: Monitoring of the second dissolved VOCs in water samples (Channel 2)

[0046] The system flow diagram of step three is shown in Figure 4. This step is for monitoring dissolved VOCs in water samples (channel 2), specifically: the first port and the third port of the first solenoid three-way valve are connected, the first port and the second port of the second solenoid three-way valve are connected, the first port and the second port of the third solenoid three-way valve are connected, the first port and the third port of the fourth solenoid three-way valve are connected, the first port and the second port of the fifth solenoid three-way valve are connected, the second port and the third port of the solenoid four-way valve are connected, and the first port and the fourth port are connected.

[0047] The second injection pump is activated, and the water sample is collected by the second injection pump and filtered through the second particulate matter pretreatment device. The filtered water sample passes through the first electromagnetic three-way valve and the third electromagnetic three-way valve, enters the dissolved state pretreatment device and is converted into a gaseous state, and then passes through the fifth electromagnetic three-way valve and enters the PTR-TOF MS for detection; the residual water in the first particulate matter pretreatment device and in the pipeline is discharged through the first electromagnetic three-way valve and the electromagnetic four-way valve.

[0048] (4) Step 4: Monitoring of second particle-state VOCs in water samples (channel 1)

[0049] The system flow diagram of step four is shown in Figure 5. This step is for monitoring particulate VOCs in water samples (channel 1), specifically: the first port and the third port of the first solenoid three-way valve are connected, the first port and the third port of the second solenoid three-way valve are connected, the first port and the second port of the third solenoid three-way valve are connected, the first port and the second port of the fourth solenoid three-way valve are connected, the first port and the third port of the fifth solenoid three-way valve are connected, the first port and the second port of the solenoid four-way valve are connected, and the third port and the fourth port are connected.

[0050] The second injection pump stops, and the residual water in the second particle pretreatment device and in the pipeline is drained through the second electromagnetic three-way valve and the electromagnetic four-way valve. The first particle pretreatment device performs thermal analysis, and high-purity nitrogen passes through the electromagnetic four-way valve, the first electromagnetic three-way valve, and the first particle pretreatment device in sequence. The analyzed VOCs are introduced into the PTR-TOF MS through the fourth electromagnetic three-way valve and the fifth electromagnetic three-way valve for detection.

[0051] After step 4 is completed, switch to step 1 again, so as to realize the cycle of the whole system and complete the online monitoring of dissolved and particulate VOCs in water samples.

[0052] The whole system provided by the utility model adopts two identical injection pumps and particle pretreatment systems, which are used crosswise in operation in a dual-channel sampling manner to ensure that functions such as filtration, emptying, and thermal analysis can be realized cyclically, and that dissolved and particle VOCs enter the PTR-TOF MS for detection in sequence without mutual interference, and also ensure that excess water remaining in the system can be emptied after filtration. On the one hand, it is easier to heat up and thermally analyze the particle VOCs, and on the other hand, it reduces the water molecule content in the sample after analysis, avoiding the generation of liquid water and water clusters during the transmission and detection process, which affects the detection performance of the system.

[0053] The solution provided by the utility model uses solenoid valves, pipes, pretreatment systems and online monitoring equipment, and through program control, ensures that the entire system cyclically monitors dissolved and particulate VOCs in water, realizes online monitoring of VOCs in multiple media, avoids the time and labor-intensive problems in laboratory methods, and the entire system has program control, which can accurately control the time, flow, temperature, etc. in sample collection, pretreatment and detection, ensures the repeatability and stability of the system, avoids the dependence on experimenters in laboratory methods, and improves the accuracy and stability of detection data.

[0054] The utility model realizes online monitoring of dissolved and particulate VOCs in water through system design, and can accurately reflect the actual VOCs content in water samples, avoiding the omissions caused by only monitoring dissolved VOCs in previous online methods, as well as data distortion caused by the mutual conversion between particulate VOCs and dissolved VOCs.

Claims

1. A particle pre-treatment device, characterized in that: include: The upper part, the lower part, the annular sealing ring, the quartz filter membrane and the stainless steel filter membrane net holder; The upper portion includes a first port and a second port; The first port is arranged at the center of the top end of the upper portion; The second port is arranged on the upper side wall and close to the top end; The lower part includes a third port and a groove buckle; the third port is arranged at the center of the bottom end of the lower part; the groove buckle is arranged at the inner side of the top end of the lower part; The stainless steel filter membrane net holder is placed in the groove, the quartz filter membrane is placed on the stainless steel filter membrane net holder, and the annular sealing ring is placed on the quartz filter membrane and is used for sealing at the connection between the upper part and the lower part.

2. The particle pretreatment device according to claim 1, characterized in that: The upper part and the lower part are made of quartz glass or stainless steel, and the outer sides thereof are wound with heating wires or heating belts.

3. Multi-media VOCs online monitoring system, characterized in that: include: A first injection pump, a second injection pump, a particle pretreatment device as described in any one of claims 1 to 2, a particle pretreatment device as described in any one of claims 1 to 2, a dissolved pretreatment device, a first electromagnetic three-way valve, a second electromagnetic three-way valve, a third electromagnetic three-way valve, a fourth electromagnetic three-way valve, a fifth electromagnetic three-way valve, an electromagnetic four-way valve, and a detection system; The first injection pump is connected to the first port of the particle pretreatment device according to any one of claims 1 to 2; The second injection pump is connected to the first port of the particle pretreatment device according to any one of claims 1 to 2; The second port of the particle pretreatment device described in any one of the first claims 1 to 2 is connected to the second port of the fourth electromagnetic three-way valve; the third port of the particle pretreatment device described in any one of the first claims 1 to 2 is connected to the first port of the first electromagnetic three-way valve; The second port of the particle pretreatment device described in any one of the second claims 1 to 2 is connected to the third port of the fourth electromagnetic three-way valve; the third port of the particle pretreatment device described in any one of the second claims 1 to 2 is connected to the first port of the second electromagnetic three-way valve; The second port of the first electromagnetic three-way valve is connected to the third port of the third electromagnetic three-way valve, and the third port of the first electromagnetic three-way valve is connected to the second port of the electromagnetic four-way valve; The second port of the second electromagnetic three-way valve is connected to the first port of the third electromagnetic three-way valve, and the third port of the second electromagnetic three-way valve is connected to the fourth port of the electromagnetic four-way valve; The first port of the third electromagnetic three-way valve is connected to the second port of the dissolved state pre-treatment device; The first port of the fourth electromagnetic three-way valve is connected to the third port of the fifth electromagnetic three-way valve; The first port of the fifth electromagnetic three-way valve is connected to the detection system, and the second port of the fifth electromagnetic three-way valve is connected to the first port of the dissolved state pre-treatment device; The first port of the electromagnetic four-way valve is connected to high-purity nitrogen, and the third port of the electromagnetic four-way valve is used for exhaust.

4. The multi-media VOCs online monitoring system according to claim 3, characterized in that: The detection system is PTR-TOF MS.

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