Method and device for determining volatile components of flue gas

Abstract

The application discloses a flue gas volatile component determination method and device. The method comprises the following steps: keeping the gas bag containing the flue gas sample in a heat preservation state; driving the flue gas to pass through the adsorption tube at a constant flow rate by using the purge gas to selectively capture the volatile components; removing water in the adsorption tube for the sample with a high water content; transferring the adsorption tube to the thermal desorption module by using the mechanical arm to heat and desorb; condensing and secondarily focusing the desorbed components in the cold trap of the cold sample inlet through the transmission line; and finally, rapidly programming the temperature of the liner tube to inject the volatile components in the form of a narrow band into the analysis instrument for analysis. The device comprises a gas bag unit, a dynamic purge unit, an adsorption unit, a desorption unit, a cold focusing and analysis unit, a mechanical arm and a control unit, and realizes fully automatic operation. The application can completely preserve the gas sample, reduce gas adsorption and condensation, selectively and efficiently capture, effectively remove water interference, and realize fully automatic high-sensitivity narrow-band injection.

Description

Technical Field

[0001] This invention relates to the field of environmental monitoring and analysis technology, and in particular to a method and apparatus for determining volatile components in flue gas. Background Technology

[0002] Currently, the main method for component and concentration detection after gas bag sampling is direct injection. Direct injection does not require pretreatment and is convenient to operate. However, the injection volume is limited. For example, the injection volume in the national ecological and environmental standards HJ38-2017, HJ 604-2017, and HJ1006-2018 is 1 mL. It has no enrichment effect and is mainly suitable for monitoring process gases and exhaust gas emissions at higher concentrations (ppm level). It has a high detection limit and is not suitable for the analysis and detection of low-content components, especially trace components. In addition, the simultaneous injection of a large amount of air (nitrogen, oxygen, water vapor) may interfere with chromatographic separation and mass spectrometry detection.

[0003] Using adsorption tubes to enrich volatile components in gases before desorption analysis is an effective solution for obtaining homogeneous gas phase samples, enhancing detection sensitivity, and improving short-term sample stability. Currently, a common approach is to use gas bags to capture flue gas and other gases, then use an air sampler and syringe pump to sample the gas phase from the gas bag into the adsorption tube at a certain flow rate. The adsorption tube is then placed in a thermal desorption instrument for desorption before sample injection and analysis. However, this technique has the following drawbacks: First, it has a low degree of automation; the adsorption process requires manual operation, and manual sample loading is necessary after adsorption, resulting in low efficiency and susceptibility to human error. Second, the high concentration of flue gas entering the adsorption tube directly may affect its adsorption effect. Third, the gas bag lacks insulation, posing a risk of condensation of analytes onto the bag surface, affecting the accuracy of the results. Fourth, the enriched sample is not specifically treated for dehydration before analysis; high moisture content leads to icing during gas condensation, affecting not only the collection efficiency of desorbed components but also severely interfering with subsequent chromatographic analysis and damaging the instrument. In view of this, we propose a method and apparatus for determining the volatile components of flue gas to overcome the above-mentioned shortcomings. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for determining volatile components in flue gas, which solves the problems existing in the prior art, can completely preserve gas samples, reduce gas adsorption and condensation, selectively and efficiently capture gas, effectively remove water interference, and achieve fully automated high-sensitivity narrow-band sampling.

[0005] To achieve the above objectives, the present invention provides the following solution: This invention provides a method for determining volatile components in flue gas, comprising the following steps: S1: Flue gas sampling and gas bag insulation: The flue gas is collected into a gas bag that has been cleaned with inert gas, and the gas bag is placed in a gas bag insulation cavity with constant temperature function for constant temperature insulation to prevent sample condensation and adsorption loss. S2: Dynamic purging and adsorption: The flue gas sample in the gas bag is purged from the bottom of the adsorption tube with a constant flow rate of purging gas, so that the volatile components in the flue gas are selectively captured in the adsorbent filled in the adsorption tube. The adsorption temperature is adjusted as needed. S3: Adsorption tube dehydration: For samples with high water content, after adsorption is complete, switch the gas path and use a constant flow rate of dehydrating gas to purge from the bottom of the adsorption tube to remove residual moisture in the adsorption tube and reduce interference with subsequent analysis. S4: Desorption and cold focusing: The adsorption tube that has completed the trapping is automatically transferred to the thermal desorption module of the injection port by the robotic arm. Heating desorption is performed at the set temperature. The desorbed components are transferred to the cold injection port through the heat-insulated transmission line. In the cold injection port, the components are trapped in the liner of the cold trap to achieve secondary condensation focusing. S5: Sample introduction and analysis: The liner is rapidly heated, and the focused volatile components are injected into the analytical instrument in a narrow band for analysis and determination.

[0006] In one embodiment, in step S1, the temperature control range of the air bag insulation cavity is 10℃~200℃, and in step S2, the air bag is continuously kept at a constant temperature during the purging process.

[0007] In one embodiment, in step S2, the purge gas is high-purity nitrogen, and its flow rate is precisely controlled by a purge gas flow controller, with a flow rate range of 0.1 mL / min to 100 mL / min.

[0008] In one embodiment, in step S2, the adsorption temperature of the adsorption tube is adjusted and controlled by an adsorption tube temperature controller, and the temperature can be controlled within a range of 20°C to 70°C. The adsorption tube can select different combinations of adsorbents according to the type of target substance (such as VOCs or SVOCs) to achieve selective capture and coverage of substances with a wide boiling range.

[0009] In one embodiment, in step S3, the dehydration gas is high-purity nitrogen gas, and its flow rate is precisely controlled by a dehydration gas flow controller, with a flow rate range of 5 mL / min to 100 mL / min.

[0010] In one embodiment, in step S4, the final desorption temperature of the adsorption tube is 10℃~350℃, and the desorption time is 0.1 min~60 min.

[0011] In one embodiment, in step S4, the cold trap low-temperature focusing temperature of the cold injection port is -150°C to 30°C.

[0012] In one embodiment, in step S5, the programmed heating rate is 0.01℃ / s ~ 12℃ / s, and the maximum temperature is 450℃.

[0013] The present invention also provides an apparatus for implementing the above-described method for determining volatile components in flue gas, comprising: The gas bag unit is used to store and keep the flue gas sample warm, including a gas bag, a fixing bracket, a gas bag insulation cavity with constant temperature function, and an interface connecting the gas bag purge gas outlet and the adsorption tube. The dynamic purging unit includes a purging gas source and a purging gas flow controller, which are used to precisely control the flow rate and drive the gas sample in the gas bag unit to be purged to the adsorption tube; The adsorption unit includes an adsorption tube for selectively capturing volatile components, and an independent gas path and a dewatering gas flow controller connected to the bottom of the adsorption tube for introducing dewatering gas. The desorption unit includes a thermal desorption module for heating the adsorption tube and an insulated transfer line for transferring the desorbed components to the liner tube in the cold injection port. The cold focusing and analysis unit includes a cold injection port with cold trap focusing function and an analytical instrument. The inlet of the cold injection port is connected to the insulated transmission line, and the outlet is connected to the inlet of the chromatographic column of the analytical instrument. Its low temperature can be provided by refrigerants such as liquid nitrogen. A robotic arm is used to automatically grasp the adsorption tube and transfer it between different stations (such as adsorption station, desorption station, and aging station). The control unit is used to coordinate and control the automatic operation of the entire device (including the aforementioned air bag unit, dynamic purging unit, adsorption unit, desorption unit, cold focusing and analysis unit, and robotic arm), including temperature, flow rate, robotic arm movement, timing, etc.

[0014] The present invention achieves the following technical effects compared to the prior art: 1. This invention integrates purging, collection, water removal, desorption, and sample injection into one unit. The entire pretreatment and sample injection analysis process can be completed automatically, enabling the quantification of components in the gas bag, leaving no residue, and efficient enrichment before direct entry into the gas chromatograph-mass spectrometer. This improves analytical efficiency and reproducibility, and has the advantages of high throughput and automation. It effectively solves the shortcomings of traditional gas bag methods, such as low sensitivity and easy sample deterioration.

[0015] 2. This invention uses purge gas to purge the flue gas in the purge bag and then into the desorption tube for enrichment. On the one hand, this reduces the flue gas concentration and increases the collection efficiency. On the other hand, the purge gas, combined with the gas bag insulation device, can reduce the residue of the target analyte on the gas bag and improve the accuracy of the analysis.

[0016] 3. This invention has a wide range of applications. It can be used for the analysis of the entire flue gas composition, avoiding the loss of some volatile components due to adsorption or penetration when Cambridge filters capture particulate matter. The fully automated analysis reduces secondary losses in the pretreatment process and can more accurately reflect the composition of the entire flue gas. It can also be used to analyze human exhaled gases and other environmental gases, among other fields.

[0017] 4. The entire process of this invention is a solvent-free technology, which reduces secondary pollution and has the advantage of being environmentally friendly.

[0018] 5. This invention combines the ultra-low temperature enrichment of the trap with the programmed temperature rise of the cold injection port, which can effectively separate and analyze trace components. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the flue gas volatile component measuring device of the present invention; Figure 2 This is a gas chromatography-mass spectrometry (GC-MS) chromatogram of cigarette smoke detected in Example 1. Figure 3 The gas chromatography-mass spectrometry (GC-MS) chromatogram of cigarette smoke detected in Comparative Example 1 is shown. Figure 4 The gas chromatography-mass spectrometry (GC-MS) chromatogram of cigarette smoke in Comparative Example 2 is shown. Figure 5 This is a gas chromatography-mass spectrometry (GC-MS) chromatogram of the exhaled smoke detected in Example 2.

[0021] In the diagram: 1-Gas bag, 2-Gas bag insulation cavity, 3-Adsorption tube, 4-Adsorption tube temperature controller, 5-Purge gas flow controller, 6-Water removal gas flow controller, 7-Robotic arm, 8-Thermal desorption module, 9-Refrigerant, 10-Insulated transmission line, 11-Liner, 12-Cold injection port, 13-Analytical instrument. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: The method of the present invention is used to determine the volatile and semi-volatile components in the smoke exhaled after smoking cigarettes. Using... Figure 1 The apparatus shown is used.

[0024] 1. Sample preparation and analysis apparatus Collect 50 mL of the exhaled smoke after inhalation into a 0.5 L Teflon gas bag 1 that has been thoroughly cleaned with high-purity nitrogen (purity >99.999%). Install the gas bag interface onto the gas bag fixing bracket of the device described in this invention and place it into the gas bag insulation cavity 2.

[0025] The device is configured as follows: the temperature of the gas bag insulation chamber 2 is set to 60℃; both the purge gas and the dehydration gas are high-purity nitrogen; the adsorption tube 3 is a Tenax TA packing adsorption tube, suitable for volatile and semi-volatile organic compounds; the thermal desorption module 8 is connected to the cold injection port 12 via an insulated transmission line 10; and the analytical instrument 13 is an Agilent 7890-5977B gas chromatograph-mass spectrometer (GC-MS).

[0026] 2. Measurement Procedure S1. Gas bag insulation: The gas bag 1 containing the flue gas sample is placed in the gas bag insulation chamber 2 at a constant temperature of 60℃ for insulation, so that the sample is uniform and adsorption and condensation are avoided.

[0027] S2. Dynamic Purging and Adsorption: The purging gas path is activated, and the purging gas flow rate is precisely controlled at 100 mL / min using the purging gas flow controller 5 (mass flow controller), and purging continues for 20 minutes. During this process, the flue gas sample passes through the adsorption tube 3 at a constant flow rate and a temperature of 20°C, where volatile components are selectively adsorbed and captured in the adsorbent filled within the adsorption tube 3. The temperature of the adsorption tube 3 is regulated and controlled by the adsorption tube temperature controller 4.

[0028] S3. Adsorption Tube Dehydration: Due to the high moisture content of exhaled smoke, the system switches to the dehydration gas path after adsorption is complete. The temperature of adsorption tube 3 is 40℃. High-purity nitrogen gas is blown from the bottom of adsorption tube 3 at a constant flow rate of 50 mL / min for 5 minutes to effectively remove residual moisture from the adsorbent. The flow rate of the high-purity nitrogen gas is precisely controlled by the dehydration gas flow controller 6.

[0029] S4. Desorption and Cold Focusing: The robotic arm 7 automatically grasps the adsorption tube 3 after dehydration and transfers it to the thermal desorption module 8. The temperature is rapidly increased to the final desorption temperature of 280℃ at a rate of 60℃ / min and held for 5 minutes. The desorbed components are then transported to the cold inlet 12 via the insulated transfer line 10. In the cold inlet 12, the components are trapped in the liner 11 of the cold trap, achieving secondary condensation and focusing. The cold trap in the cold inlet 12 uses liquid nitrogen refrigerant 9, which condenses and focuses the desorbed material at -70℃.

[0030] S5. Rapid injection and GC-MS analysis: The cold trap was rapidly heated to 285°C at a rate of 10°C / s and held for 3 minutes. The focused fraction was then instantaneously injected into the GC-MS system in a narrow band. GC was performed using a DB-5MS column (60 m × 0.25 mm × 0.25 μm), splitless injection mode, and a programmed temperature ramp: initial temperature of 40°C for 5 minutes, ramped to 170°C at 2°C / min, then ramped to 300°C at 10°C / min and held for 5 minutes. Mass spectrometry was performed using an electron impact (EI) ion source in full scan mode (Scan, m / z 35-550).

[0031] 3. Results and Effects This embodiment successfully detected 264 target compounds in the smoke exhaled after cigarette smoking. The gas chromatography-mass spectrometry (GC-MS) chromatograms are attached. Figure 2 Table 1 lists only the major substances with a relative content higher than 0.1%, including ketones (24 types), heterocyclic compounds (20 types), alkenes (28 types), alkanes (13 types), monocyclic aromatic hydrocarbons (13 types of benzene series), polycyclic aromatic hydrocarbons (15 types), esters (9 types), alcohols (8 types), phenols (8 types), aldehydes (4 types), acids (2 types), nitriles (2 types), alkynes (2 types), and sugars (1 type). The detectable substances cover different functional group types, polarities, and boiling points, making it widely applicable. The pretreatment and sample injection processes are fully automated, reducing errors from manual processing. The relative standard deviation of three parallel determinations is less than 10%, demonstrating good precision and repeatability of the method. Compared with traditional direct thermal desorption injection, this method significantly reduces the interference of water peaks on the chromatogram through the water removal step, and improves the detection sensitivity of early eluting volatile components. At the same time, cold focusing injection makes the chromatographic peaks of semi-volatile components sharper and more symmetrical, realizing comprehensive and highly sensitive analysis of the complex matrix of cigarette smoke.

[0032] Table 1. List of major compounds detected (relative content higher than 0.1%)

[0033] Comparative Example 1: After sampling with a gas bag, the volatile and semi-volatile components in the exhaled smoke after smoking cigarettes were determined directly.

[0034] 1. Sample preparation and analysis apparatus The air bag sampling procedure and analysis instruments are the same as in Example 1.

[0035] 2. Measurement Procedure S1. Gas bag insulation: The gas bag 1 containing the flue gas sample is placed in the gas bag insulation cavity 2 at a constant temperature of 60℃ for insulation.

[0036] S2. Direct Flue Gas Sampling and Cold Focusing: Using a headspace sampling needle, 2.0 mL of flue gas sample is directly extracted from gas bag 1 and rapidly injected into the cold injection port. The cold trap in the cold injection port is cooled with liquid nitrogen, and the injected flue gas sample is condensed and focused at -70℃.

[0037] S3. Rapid sample introduction and GC-MS analysis: The cold trap temperature program and GC-MS analysis conditions are the same as in Example 1.

[0038] 3. Results and Effects Using this comparative method, a total of 57 target compounds were detected in the flue gas. The gas chromatography-mass spectrometry (GC-MS) chromatograms are attached. Figure 3 Compared to Example 1, this method significantly reduces the number of detected substances and lowers the chromatographic peak response values. Direct gas injection, with a small injection volume of only 2.0 mL, resulted in peak response values ​​for each component being far lower than in Example 1, a significant decrease in signal-to-noise ratio, and low sensitivity. The average relative standard deviation (RSD) of three parallel determinations was 15%, with some low-content components showing RSDs exceeding 20%, indicating generally poor repeatability. Early elution regions in the chromatogram showed interference from carbon dioxide peaks, masking some low-boiling-point volatile components and making qualitative and quantitative analysis difficult. The method lacks a dehydration function, allowing a large amount of moisture in the flue gas to enter the cold trap system. This not only reduces condensation efficiency and affects detection sensitivity but also leads to incomplete volatilization of high-boiling-point substances in the cold trap, significantly reducing the number of detected peaks for high-boiling-point substances; no chromatographic peaks were detected after 42 minutes. This indicates that the direct injection method after gas bag sampling, lacking sample purging, enrichment, and dehydration steps, is poorly adaptable to exhaled flue gas matrices with high water content and complex composition, exhibiting problems such as low sensitivity, poor selectivity, and poor repeatability.

[0039] In summary, the direct injection method represented by this comparative example has significant limitations in terms of sensitivity, selectivity, repeatability, and applicability to complex wet matrices. This further highlights the necessity and superiority of the combined dynamic purge adsorption, online water removal, thermal desorption, and cold focusing technology used in this invention (Example 1).

[0040] Comparative Example 2: Manual sampling-thermal desorption method was used to determine the volatile and semi-volatile components in the smoke exhaled after smoking cigarettes.

[0041] 1. Sample preparation and analysis apparatus Collect 50 mL of exhaled smoke after inhalation into a 0.5 L Teflon gas bag 1 that has been thoroughly cleaned with high-purity nitrogen (purity >99.999%). Gas bag 1 is connected to a syringe pump via polytetrafluoroethylene tubing. The adsorption tube 3 is the same Tenax TA packed adsorption tube as in Example 1. The analytical instrument 13 is an Agilent 7890-5977B gas chromatograph-mass spectrometer (GC-MS) as in Example 1, with its front end connected to a thermal desorption-cold injection unit.

[0042] 2. Measurement Procedure S1. Manual Sampling and Adsorption: The operator manually installs the adsorption tube 3 into the sampling pipeline, starts the syringe pump, and draws the flue gas captured in the gas bag 1 through the adsorption tube 3 at a constant flow rate of 100 mL / min, so that the flue gas components are adsorbed onto the adsorbent. This process requires manual installation, start-up, and control by the operator.

[0043] S2. Adsorption tube transfer and installation: After sampling, manually disassemble the sampling tubing, remove adsorption tube 3, and transfer it to the desorption position of the thermal desorption instrument.

[0044] S3. Desorption and cold focusing: This process is the same as in Example 1.

[0045] S4. Sample injection and GC-MS analysis: This procedure is the same as in Example 1.

[0046] 3. Results and Effects Using this comparative method, approximately 83 target compounds were detected in the exhaled smoke after cigarette smoking. The detection count was lower than that in Example 1. The gas chromatography-mass spectrometry chromatograms are attached. Figure 4Compared with Example 1, this method has the following limitations. (1) Low degree of automation: Sampling, adsorption tube transfer and installation all rely on manual operation, which is cumbersome and easy to introduce operational errors, resulting in an average relative standard deviation (RSD) of 20% for three parallel determinations, and poor reproducibility of the method. (2) Poor selectivity of adsorption process and high chromatographic background value: High concentration flue gas passes directly through the adsorption tube in a short time, which may cause strong adsorption components (such as some high boiling point substances) to over-occupy adsorption sites, affecting the adsorption balance of volatile components, and easily causing contamination of adsorption tube and chromatographic column; the high chromatographic baseline background affects the qualitative and quantitative analysis of low content components, especially after 80 min, a large amount of high boiling point components flow out, so the number of detected substances is also significantly reduced. (3) Lack of online water removal step: A large amount of water in the flue gas directly enters the adsorption tube and is desorbed together during thermal desorption, condensing in the cold trap, which not only reduces the cooling efficiency, but also interferes with the effective volatilization and focusing of the target, further affecting the sensitivity of detection. (4) Gas bag insulation and purging design: The gas bag is in a room temperature environment, where semi-volatile and high-boiling-point components are easily condensed and adsorbed on the bag wall, and cannot be effectively transferred to the adsorption tube; at the same time, the injection pump sampling is "extraction" type, which cannot achieve the dynamic and constant temperature purging in Example 1, resulting in insufficient sample representativeness and poor selectivity.

[0047] In summary, this manual sampling-thermal desorption method is significantly inferior to the integrated, fully automated, online water removal analysis scheme provided in Example 1 of this invention in terms of operational efficiency, detection sensitivity, reproducibility, and matrix adaptability.

[0048] Example 2: The method of the present invention is used for the determination of trace VOCs and odor components in ambient air (gas in a reagent storage cabinet). Using... Figure 1 The apparatus shown is used.

[0049] 1. Sample preparation and analysis apparatus In the reagent and fragrance standard storage cabinet, a sampling pump is used to collect 200 mL of contaminated, odorous ambient air from the storage cabinet into a 1 L inerted aluminum foil gas bag 1. The gas bag interface is then installed on the gas bag fixing bracket of the device described in this invention and placed into the gas bag insulation cavity 2.

[0050] The device configuration is adjusted as follows: the temperature of the air bag insulation chamber 2 is set to the ambient temperature (25°C); the adsorption tube 3 is a Carbopack B, Carbopack X and Carboxen 1000 composite filler adsorption tube, which is specifically designed for the efficient collection of C2-C12 volatile organic compounds; the rest of the device is the same as in Example 1.

[0051] 2. Measurement Procedure S1. Gas bag insulation: Place the gas bag 1 containing the flue gas sample into the gas bag insulation chamber 2 at a constant temperature of 25°C, and proceed directly to the next step without additional balancing.

[0052] S2. Dynamic Purging and Adsorption: Due to the low concentration of the target substance in the ambient air, a low-flow-rate, long-duration purging enrichment method was employed. The purging gas path was opened, and the purging gas flow rate was precisely controlled at 20 mL / min using a mass flow controller, with continuous purging for 50 minutes. During this process, the flue gas sample passed through the adsorption tube 3 at a constant flow rate and a temperature of 30°C, where volatile components were selectively adsorbed and captured in the adsorbent filled within the adsorption tube 3.

[0053] S3. Adsorption tube dehydration: In this embodiment, the ambient air humidity is relatively low, so the dehydration step is skipped according to the preset program.

[0054] S4. Desorption and Cold Focusing: The robotic arm 7 automatically grasps the adsorption tube 3 after adsorption and transfers it to the thermal desorption module 8. The temperature is rapidly increased to the final desorption temperature of 260℃ at a rate of 80℃ / min and held for 3 minutes. The desorbed components are then transported to the cold inlet 12 via the insulated transfer line 10. In the cold inlet 12, the components are captured in the liner 11 of the cold trap, achieving secondary condensation and focusing. The cold trap in the cold inlet 12 uses liquid nitrogen refrigerant 9, which condenses and focuses the desorbed material at -120℃.

[0055] S5. Rapid injection and GC-MS analysis: The cold trap was rapidly heated to 265°C at a rate of 8°C / s and held for 2 minutes. The focused fraction was then instantaneously injected into the GC-MS system in a narrow band. GC was performed using a PLOT-Q column (30m × 0.32 mm × 20 μm), split injection mode, split ratio 5:1, and a programmed temperature increase: initial temperature of 40°C held for 4 minutes, increased to 200°C at 2°C / min, then increased to 270°C at 5°C / min and held for 15 minutes. Mass spectrometry was performed using an electron impact (EI) ion source in full scan mode (Scan, m / z 35-550).

[0056] 3. Results and Effects This embodiment effectively detected multiple types of volatile organic compounds and leaked volatile standards in the ambient air of the reagent storage cabinet. Gas chromatography-mass spectrometry (GC-MS) chromatograms are attached. Figure 5Table 2 lists only the main substances detected, including 16 alkenes, 6 benzene derivatives, 15 alkanes, 12 esters, 5 aldehydes, 2 ketones, 2 alcohols, 2 phenols, 2 terpenes, 1 polycyclic aromatic hydrocarbon, 1 chlorinated hydrocarbon, 1 alkaloid, and 1 amide, totaling 67 characteristic components. The most abundant components are (d)-limonene, dichloromethane, γ-terpinene, β-pinene, and ethyl acetate, which can directly identify the main pollutants and guide the proper and safe storage of reagents. The method is fully automated, requiring no human intervention, and the relative standard deviation (RSD) of repeated samples is less than 10%. Compared with traditional methods of manual sampling followed by laboratory analysis, this invention enables fully automated analysis to be started immediately after on-site sampling, greatly shortening sample turnaround time and avoiding loss and contamination during sample storage and transportation. It is particularly suitable for environmental emergency monitoring and pollution source tracing analysis.

[0057] Table 2 List of major compounds detected

[0058] The above embodiments demonstrate that the method and apparatus provided by the present invention can flexibly, efficiently, and sensitively handle smoke samples from different sources (such as high-humidity, high-concentration cigarette smoke and low-concentration ambient air) and with different properties. Through automated processes and the core design of "dynamic purge adsorption-water removal-cold focusing injection", the accuracy, sensitivity, and throughput of volatile and semi-volatile organic compound analysis are significantly improved.

[0059] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for determining volatile components in flue gas, characterized in that, Includes the following steps: S1: Flue gas sampling and gas bag insulation: The flue gas is collected into a gas bag that has been cleaned with inert gas, and the gas bag is placed in a gas bag insulation cavity with constant temperature function for constant temperature insulation. S2: Dynamic purging and adsorption: The flue gas sample in the gas bag is blown in from the bottom of the adsorption tube with a constant flow rate of purging gas, so that the volatile components in the flue gas are selectively captured in the adsorbent filled in the adsorption tube. S3: Adsorption tube dehydration: For samples with high water content, after adsorption is complete, switch the gas path and use a constant flow rate of dehydrating gas to purge from the bottom of the adsorption tube to remove residual moisture in the adsorption tube and reduce interference with subsequent analysis. S4: Desorption and cold focusing: The adsorption tube that has completed the trapping is automatically transferred to the thermal desorption module of the injection port by the robotic arm. Heating desorption is performed at the set temperature. The desorbed components are transferred to the cold injection port through the heat-insulated transmission line. In the cold injection port, the components are trapped in the liner of the cold trap to achieve secondary condensation focusing. S5: Sample introduction and analysis: The liner is heated by a programmed temperature increase, and the focused volatile components are injected into the analytical instrument in a narrow band for analysis and determination.

2. The method for determining volatile components in flue gas according to claim 1, characterized in that: In step S1, the temperature control range of the air bag insulation cavity is 10℃~200℃. In step S2, the air bag is continuously kept at a constant temperature during the purging process.

3. The method for determining volatile components in flue gas according to claim 1, characterized in that: In step S2, the purge gas is high-purity nitrogen, and its flow rate is precisely controlled by a purge gas flow controller, with a flow rate range of 0.1 mL / min to 100 mL / min.

4. The method for determining volatile components in flue gas according to claim 1, characterized in that: In step S2, the adsorption temperature of the adsorption tube is adjusted and controlled by the adsorption tube temperature controller, and the temperature can be controlled within the range of 20℃~70℃.

5. The method for determining volatile components in flue gas according to claim 1, characterized in that: In step S3, the dewatering gas is high-purity nitrogen gas, and its flow rate is precisely controlled by a dewatering gas flow controller, with a flow rate range of 5 mL / min to 100 mL / min.

6. The method for determining volatile components in flue gas according to claim 1, characterized in that: In step S4, the final desorption temperature of the adsorption tube is 10℃~350℃, and the desorption time is 0.1 min~60 min.

7. The method for determining volatile components in flue gas according to claim 1, characterized in that: In step S4, the cold trap low-temperature focusing temperature of the cold injection port is -150℃ to 30℃.

8. The method for determining volatile components in flue gas according to claim 1, characterized in that: In step S5, the programmed heating rate is 0.01℃ / s ~ 12℃ / s, and the maximum temperature is 450℃.

9. An apparatus for implementing the method for determining volatile components of flue gas according to any one of claims 1-8, characterized in that, include: The gas bag unit is used to store and keep the flue gas sample warm, including a gas bag, a fixing bracket, a gas bag insulation cavity with constant temperature function, and an interface connecting the gas bag purge gas outlet and the adsorption tube. The dynamic purging unit includes a purging gas source and a purging gas flow controller, which are used to precisely control the flow rate and drive the gas sample in the gas bag unit to be purged to the adsorption tube; The adsorption unit includes an adsorption tube for selectively capturing volatile components, and an independent gas path and a dewatering gas flow controller connected to the bottom of the adsorption tube for introducing dewatering gas. The desorption unit includes a thermal desorption module for heating the adsorption tube and an insulated transfer line for transferring the desorbed components to the liner tube in the cold injection port. The cold focusing and analysis unit includes a cold injection port with cold trap focusing function and an analytical instrument. The inlet of the cold injection port is connected to the insulated transmission line, and the outlet is connected to the chromatographic column inlet of the analytical instrument. A robotic arm is used to automatically grasp the adsorption tube and transfer the adsorption tube between different workstations; The control unit is used to coordinate and control the automatic operation of the entire device.

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