Device for measuring total hydrocarbon, non-methane total hydrocarbon and benzene series in gas

Abstract

The application discloses a device for measuring total hydrocarbon, non-methane total hydrocarbon and benzene series in gas, which comprises a total hydrocarbon separation column, a methane benzene series separation column, a gas chromatography sampling port, an FID hydrogen flame ionization detector, a six-way valve, a sample gas gas path, a hydrocarbon-removing air gas path, a to-be-measured sample gas source, an air source and a carrier gas source; the total hydrocarbon separation column and the methane benzene series separation column are respectively connected with the gas chromatography sampling port and the FID hydrogen flame ionization detector sampling port at two ends. The sample gas gas path is connected with the to-be-measured sample gas source and the six-way valve No. 3. The device can replace the complex multi-valve low-temperature enrichment configuration in the prior art, greatly simplifies the instrument structure, reduces the hardware cost and the maintenance complexity, and can realize upgrading on a conventional gas chromatography platform, so that the detection threshold and cost are greatly reduced.

Description

Technical Field

[0001] This application relates to the field of gas detection technology, and in particular to an apparatus for determining total hydrocarbons, non-methane hydrocarbons, and benzene compounds in a gas. Background Technology

[0002] Non-methane hydrocarbons refer to all volatile hydrocarbons other than methane. Benzene compounds refer to benzene, toluene, ethylbenzene, and three types of xylene. As environmental pollutants, non-methane hydrocarbons and benzene compounds have significant impacts on the environment and human health.

[0003] Currently, the determination of methane and non-methane total hydrocarbons in stationary pollution sources is usually carried out according to HJ38-2017 "Determination of Total Hydrocarbons, Methane and Non-methane Total Hydrocarbons in Exhaust Gas from Stationary Pollution Sources by Gas Chromatography", while the determination of benzene series compounds is usually carried out according to HJ1261-2022 "Determination of Benzene Series Compounds in Exhaust Gas from Stationary Pollution Sources by Gas Bag Sampling / Direct Injection-Gas Chromatography".

[0004] Existing equipment for determining methane and non-methane total hydrocarbon pollutants integrates analytical modules for non-methane total hydrocarbons and benzene series compounds. It achieves continuous, automated analysis within a single instrument through methods such as 10-way or 12-way valve shut-off or cryogenic enrichment. While this method improves analytical efficiency to some extent, it still relies on complex flow path design and numerous high-precision valves to control the feed and discharge of materials at each detection stage. This results in a complex overall structure and high cost.

[0005] Moreover, the standard configuration of existing gas chromatographs cannot meet the requirement of a single device simultaneously detecting methane and non-methane total hydrocarbon pollutants.

[0006] The information disclosed in the background section is intended only to enhance the understanding of the overall background of this utility model and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Utility Model Content

[0007] This application addresses the aforementioned technical problems by providing an apparatus for determining total hydrocarbons, non-methane hydrocarbons, and benzene compounds in gases. This apparatus is simple in structure, low in cost, and capable of simultaneous analysis of methane, non-methane hydrocarbons, and benzene compounds. Based on a conventional gas chromatography platform, only a single six-way valve is required, eliminating the need for complex multi-valve switching and flow path reconfiguration. This allows for rapid separation and accurate determination of the three target compounds under a single injection condition, effectively solving the problems of high equipment investment, cumbersome operation, and difficulty in upgrading conventional laboratory instruments in existing methods.

[0008] This application provides an apparatus for determining total hydrocarbons, non-methane hydrocarbons, and benzene series compounds in a gas, comprising: a total hydrocarbon separation column, a methane-benzene series compound separation column, a gas chromatograph inlet, a FID flame ionization detector, a six-way valve, a sample gas path, a hydrocarbon-removing air path, a sample gas source, an air source, and a carrier gas source. The two ends of the total hydrocarbon separation column and the methane benzene series separation column are respectively connected to the gas chromatograph outlet and the FID flame ionization detector inlet; The sample gas path is connected to the sample gas source and position 3 of the six-way valve; The hydrocarbon removal air path connects to the air source and position 3 of the six-way valve; The carrier gas source is connected to the pipeline at position 1 of the six-way valve; position 6 of the six-way valve is connected to the pipeline at the gas chromatograph inlet; position 4 of the six-way valve is connected to the pipeline at the gas vent outlet. The two ends of the metering loop are connected to position 2 and position 5 of the six-way valve, respectively; In the "sample replacement" state, positions 2 and 3 of the six-way valve are connected; positions 5 and 4 of the six-way valve are connected. When in the "sample injection" state, positions 2 and 3 of the six-way valve are connected; positions 5 and 6 of the six-way valve are connected.

[0009] Preferably, it includes: a first straight-through valve and a second T-shaped tee; the first straight-through valve and the second T-shaped tee are spaced apart on the sample gas line; The third port of the second T-shaped tee is connected to the vent pipe.

[0010] Preferably, it includes: a hydrocarbon removal device, a second straight-through valve, and a first T-shaped tee; the hydrocarbon removal device, the second straight-through valve, and the first T-shaped tee are spaced apart on the hydrocarbon removal air path; The third port of the first T-shaped tee is connected to the vent pipe.

[0011] Preferably, the hydrocarbon removal device includes: a tank, an activated carbon adsorption material layer, and baffles; baffles are installed at both ends of the tank; and an activated carbon adsorption material layer is filled between the baffles.

[0012] Preferably, it includes: a first EPC controller; the first EPC controller is installed on the pipeline connecting the carrier gas source and position 1 of the six-way valve.

[0013] Preferably, it includes: a second EPC controller; the air source is connected to the air inlet pipe of the FID hydrogen flame ionization detector, and the second EPC controller is installed on the connecting pipe.

[0014] Preferably, it includes: a nitrogen source and a third EPC controller; the third EPC controller is installed on the pipeline connecting the nitrogen source and the nitrogen inlet of the FID flame ionization detector.

[0015] Preferably, it includes: a Y-shaped tee; The second port of the Y-shaped tee is connected to the pipeline at position 3 of the six-way valve; The first port of the Y-shaped tee is connected to the hydrocarbon removal air passage; The second port of the Y-shaped tee is connected to the sample gas path.

[0016] Preferably, it includes: a two-hole graphite pad; a two-hole graphite pad is provided on the sample outlet of the gas chromatograph; a two-hole graphite pad is provided on the sample inlet of the FID flame ionization detector; One end of the total hydrocarbon separation column is inserted into a two-hole graphite pad at the outlet of the gas chromatograph, and the other end is inserted into a two-hole graphite pad at the inlet of the FID flame ionization detector. One end of the methane-benzene separation column is inserted into a two-hole graphite pad at the outlet of the gas chromatograph, and the other end is inserted into a two-hole graphite pad at the inlet of the FID flame ionization detector.

[0017] Preferably, the methane-benzene separation column has a length of 30 m, an inner diameter of 0.32 mm, and a membrane thickness of 1 μm.

[0018] The beneficial effects that this application can produce include: 1) The apparatus provided in this application for determining total hydrocarbons, non-methane hydrocarbons and benzene series compounds in gases effectively reduces hardware costs and maintenance complexity, and can be upgraded on a conventional gas chromatography platform, significantly reducing the detection threshold and cost.

[0019] 2) The apparatus provided in this application for determining total hydrocarbons, non-methane hydrocarbons, and benzene compounds in gases can achieve automated continuous analysis of all target compounds, including methane, non-methane hydrocarbons, and benzene compounds, in a single injection. This eliminates the need for separate injections and measurements, simplifying operation, reducing time consumption, improving analytical efficiency, and alleviating the workload of operators. The apparatus has a wide range of applications and is beneficial for enhancing environmental monitoring capabilities in large-scale industrial production. Attached Figure Description

[0020] Fig. 1 A schematic diagram of an apparatus for determining total hydrocarbons (non-methane hydrocarbons) and benzene compounds in a gas according to at least one embodiment provided in this application; Fig. 2 A schematic diagram of a dual-hole graphite pad in at least one embodiment provided in this application; a is a top view; b is a front view; Legend: Six-way valve No. 1, No. 2, No. 3, No. 4, No. 5, No. 6; Total hydrocarbon separation column; Methane-benzene series separation column; Gas chromatograph injection port; FID flame ionization detector; Quantitative loop; First straight-through valve; Second straight-through valve; First EPC controller; Second EPC controller; Third EPC controller; Hydrocarbon removal device; Six-way valve; Y-shaped tee; First T-shaped tee; Second T-shaped tee; First damping tube; Second damping tube; First double-hole graphite pad; Second double-hole graphite pad; First gas vent 111, second gas vent 112, third gas vent 113, plug 114, through hole 115, tank 121, activated carbon adsorption material layer 122, baffle plate 123. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] Technical means not detailed in this application and not used to solve the technical problems of this application are all set according to common knowledge in the art, and multiple common knowledge setting methods can be used to achieve this. The gas chromatograph, FID flame ionization detector and related detection devices used in this application, the sample gas source and air source are set according to commonly used devices in the art, and will not be repeated here. The sample gas source, air source, nitrogen source and argon source can be gas storage tanks. The six-way valve 18 used can connect / disconnect any two adjacent ports.

[0024] See Figs. 1-2The apparatus provided in this application for determining total hydrocarbons, non-methane hydrocarbons, and benzene series compounds in a gas includes: a six-way valve at position 1, a six-way valve at position 2, a six-way valve at position 3, a six-way valve at position 4, a six-way valve at position 5, a six-way valve at position 6, a total hydrocarbon separation column, a methane-benzene series compound separation column, a gas chromatograph injection port, a FID flame ionization detector, a quantitative loop, a first straight-through valve, a second straight-through valve, a first EPC, a second EPC, a third EPC, a hydrocarbon removal device, a six-way valve, a Y-shaped tee, a first T-shaped tee, a second T-shaped tee, a first damping tube, a second damping tube, a first double-hole graphite pad, and a second double-hole graphite pad. The first position of the six-way valve is connected to the argon gas source pipeline, and the first EPC flow controller 14 is installed on the connecting pipeline; the sixth position of the six-way valve is connected to the gas chromatograph inlet 9 pipeline; the two ends of the quantitative loop 11 are connected to the second position of the six-way valve and the fifth position of the six-way valve, respectively; the third position of the six-way valve is connected to the sample gas pipeline and the hydrocarbon removal air pipeline, respectively; the fourth position of the six-way valve is connected to the first gas vent 111 pipeline.

[0025] The sample gas path and the hydrocarbon-removing air path include: an air source, a sample gas inlet, and a Y-shaped tee 19; the sample gas inlet is connected to the first port of the Y-shaped tee 19, and a first straight-through valve 12 and a second T-shaped tee 21 are installed on the connecting pipe; the third port of the second T-shaped tee 21 is connected to the third gas vent 113, and a second damping pipe 23 is installed on the connecting pipe. The second port of the second T-shaped tee 21 is connected to the first port of the Y-shaped tee 19; the second port of the Y-shaped tee 19 is connected to the 3rd position of the 6-way valve. The third port of the Y-shaped tee 19 is connected to the air source pipeline. A hydrocarbon removal device 17, a second straight valve 13, and a first T-shaped tee 20 are installed on the connecting pipeline. The third port of the first T-shaped tee 20 is connected to the second air venting port 112 pipeline. A first damping pipe 22 is installed on the connecting pipeline.

[0026] By employing the aforementioned sample gas path and hydrocarbon removal air path, dead volume contamination of the sample in the pipeline is avoided during sample replacement. A hydrocarbon removal device 17 is connected to the air pipeline to remove organic hydrocarbon components from the air. When sample analysis is required, the first straight-through valve 12 is opened to connect the sample source to the six-way valve 18, and the second straight-through valve 13 is closed to shut down the hydrocarbon removal air pipeline. When blank determination is required, the first straight-through valve 12 in the sample gas path is closed, and the second straight-through valve 13 in the hydrocarbon removal air pipeline is opened, achieving independent control and interference-free switching between the two airflow paths.

[0027] One end of the methane-benzene series separation column 8 is connected to the outlet pipeline of the gas chromatograph injection port 9, and the other end is connected to the inlet pipeline of the FID flame ionization detector 10; One end of the total hydrocarbon separation column 7 is connected to the outlet pipeline of the gas chromatograph injection port 9, and the other end is connected to the inlet pipeline of the FID flame ionization detector 10.

[0028] The hydrogen inlet of the FID hydrogen flame ionization detector 10 is connected to a hydrogen source pipeline, and a third EPC flow controller 16 is installed on the connecting pipeline; the air inlet of the FID hydrogen flame ionization detector 10 is connected to an air source pipeline, and a second EPC flow controller 15 is installed on the connecting pipeline. The second EPC controller 15 and the third EPC controller 16 are used to provide stable combustion-supporting gas and combustion-supporting gas to the FID hydrogen flame ionization detector 10, respectively.

[0029] In one specific embodiment, it includes: a first dual-pore graphite pad 24; the first dual-pore graphite pad 24 is disposed on the outlet of the gas chromatograph inlet 9 so that the outlet of the gas chromatograph inlet 9 is simultaneously connected to the methane benzene series separation column 8 and the total hydrocarbon separation column 7; In one specific embodiment, it includes: a second double-hole graphite pad 25; the second double-hole graphite pad 25 is disposed on the inlet of the FID flame ionization detector 10, and is used to enable the inlet of the FID flame ionization detector 10 to be simultaneously connected to the methane benzene series separation column 8 and the total hydrocarbon separation column 7.

[0030] In one specific embodiment, the first double-hole graphite pad 24 and the second double-hole graphite pad 25 have the same structure, including: a plug body 114 and a through hole 115; the through holes 115 are symmetrically opened on the plug body.

[0031] In one specific embodiment, the specifications of the methane-benzene series separation column 8 are: length 30 m, inner diameter 0.32 mm, membrane thickness 1 μm, and stationary liquid 100% dimethylpolysiloxane.

[0032] In one specific embodiment, the total hydrocarbon separation column 7 is an empty chromatography column with a length of 5 m and a diameter of 0.32 mm.

[0033] Preferably, the metering ring 11 is in 2ml specification.

[0034] Preferably, both the first straight-through valve 12 and the second straight-through valve 13 are two-way valves with a 1 / 16-inch interface.

[0035] Preferably, the hydrocarbon removal device 17 includes: a tank 121, an activated carbon adsorbent layer 122, and baffles 123; baffles 123 are respectively provided at both ends of the tank 121, and activated carbon adsorbent is filled between the baffles 123 to form an activated carbon adsorbent layer 122. The particle size of the activated carbon adsorbent is larger than the vent holes opened on the baffles 123, so that after the gas enters the tank, the hydrocarbons in the gas are removed through the activated carbon adsorbent layer 122; the tank 121 is made entirely of stainless steel and has a size of Ø3 cm × 20 cm; the activated carbon adsorbent layer 122 is a layer formed by filling activated carbon adsorbent.

[0036] Preferably, the diameter of the through hole 115 opened on the plug body 114 of the first double-hole graphite pad 24 and the second double-hole graphite pad 25 is 0.32mm.

[0037] Unless otherwise specified, all materials and instruments used in the following embodiments were obtained through commercial channels; and all detection methods used are existing methods unless otherwise specified.

[0038] Application examples: 1. Blank determination: Set the six-way valve 18 to the "sample replacement" state, close the first straight-through valve 12 in the sample gas line, and open the second straight-through valve 13 in the hydrocarbon removal air line. Allow the pure air purified by the hydrocarbon removal device 17 to enter from position 3 of the six-way valve at a flow rate of approximately 50 mL / min, flow through position 2, quantitative loop 11, position 5, and finally be purged from position 4 to remove residual sample components in the pipeline and quantitative loop 11. After purging for 1 minute, switch the six-way valve 18 to the "sample injection" state. At this time, the carrier gas argon enters the six-way valve 18 through position 1, flows through position 2 into the quantitative loop 11, and then flows out from position 5. Connect the six-way valves position 5 and 6 to push the gas remaining in the quantitative loop 11 from position 6 to the gas chromatograph injection port 9. Then, the sample enters the total hydrocarbon separation column 7 and the methane benzene series separation column 8, respectively. Since the total hydrocarbon separation column 7 has no retention capacity, it initially generates an air blank peak on the FID flame ionization detector 10. The methane-benzene series separation column 8 is used to determine the hydrocarbon background value in the chromatographic column system. This blank value will be automatically recorded by the data processing software and used to correct subsequent sample determination results. This enables the simultaneous detection of multiple components.

[0039] 2. Sample Analysis: Switch the six-way valve 18 back to the "sample replacement" state. Close the second straight-through valve 13 of the hydrocarbon removal air path and open the first straight-through valve 12 of the sample gas path. The sample gas flows sequentially from position 3 of the six-way valve, through positions 2 and 5, and is purged from position 4 to remove any remaining sample and fill the quantitative loop 11, ready for the subsequent carrier to carry the sample gas into the subsequent detection. Continue purging for more than 1 minute to ensure that the gas in the quantitative loop 11 is completely replaced by the sample.

[0040] Then, the six-way valve 18 is quickly switched to the "injection" state. At this time, the carrier gas argon enters from position 1 of the six-way valve, passes through position 2 and enters the quantitative loop 11, which drives the sample gas in the quantitative loop 11 to exit from position 5, and then exits through position 6 connected to position 5, and enters the injection port 9. In the injection port 9, the sample gas is split into two parts. One part enters the total hydrocarbon separation column 7 and the other part enters the methane benzene series separation column 8. After the components are separated in the chromatographic column, they enter the FID flame ionization detector 10 to obtain the detection results and record them, thus completing the detection.

[0041] Following the above usage method, the standard gases purchased for each substance shown in Table 1 were tested using this device, and the resulting calibration curves are shown in Table 1. Based on the standard calibration curves, the same samples were subjected to precision tests, and the results are listed in Table 2.

[0042] Table 1. Results of the standard calibration curve Table 2 Precision Test Results As can be seen from Tables 1 and 2, the precision of the results obtained using the device provided in this application for the standard samples: total hydrocarbons, methane, benzene, toluene, ethylbenzene, p-xylene, m-xylene, and o-xylene is good, indicating that the device can effectively detect the above gases.

[0043] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An apparatus for determining total hydrocarbons (excluding methane) and benzene compounds in a gas, characterized in that, include: Total hydrocarbon separation column (7), methane benzene series separation column (8), gas chromatograph injection port (9), FID flame ionization detector (10), six-way valve (18), sample gas path, hydrocarbon removal air path, sample gas source, air source, carrier gas source; The two ends of the total hydrocarbon separation column (7) and the methane benzene series separation column (8) are respectively connected to the gas chromatograph outlet and the FID flame ionization detector (10) inlet; The sample gas path is connected to the sample gas source and position 3 of the six-way valve (3); The hydrocarbon removal air path is connected to the air source and the 3rd position of the six-way valve (3); The carrier gas source is connected to the pipeline at position 1 (1) of the six-way valve; the pipeline at position 6 (6) of the six-way valve is connected to the pipeline at the gas chromatograph injection port (9); the pipeline at position 4 (4) of the six-way valve is connected to the pipeline at the gas vent. The two ends of the metering ring (11) are connected to position 2 (2) of the six-way valve and position 5 (5) of the six-way valve, respectively; In the "sample replacement" state, position 2 (2) of the six-way valve and position 3 (3) of the six-way valve are connected; position 5 (5) of the six-way valve and position 4 (4) of the six-way valve are connected. When in the "sample injection" state, position 2 (2) of the six-way valve and position 3 (3) of the six-way valve are connected; position 5 (5) of the six-way valve and position 6 (6) of the six-way valve are connected.

2. The apparatus for determining total hydrocarbons, non-methane hydrocarbons, and benzene series compounds in a gas according to claim 1, characterized in that, include: First straight valve (12), second T-shaped tee (21); the first straight valve (12) and the second T-shaped tee (21) are spaced apart on the sample gas line. The third port of the second T-shaped tee (21) is connected to the vent pipe.

3. The apparatus for determining total hydrocarbons, non-methane hydrocarbons, and benzene series compounds in a gas according to claim 1, characterized in that, include: Hydrocarbon removal device (17), second straight-through valve (13), first T-shaped tee (20); the hydrocarbon removal device (17), second straight-through valve (13), and first T-shaped tee (20) are installed at intervals on the hydrocarbon removal air path; The third port of the first T-shaped tee (20) is connected to the vent pipe.

4. The apparatus for determining total hydrocarbons, non-methane hydrocarbons, and benzene series compounds in a gas according to claim 3, characterized in that, The hydrocarbon removal device (17) includes: a tank (121), an activated carbon adsorption material layer (122), and baffles (123); baffles (123) are installed at both ends of the tank (121); and activated carbon adsorption material layer (122) is filled between the baffles (123).

5. The apparatus for determining total hydrocarbons, non-methane hydrocarbons, and benzene series compounds in a gas according to claim 1, characterized in that, include: First EPC controller (14); The first EPC controller (14) is installed on the pipeline connecting the carrier gas source and the six-way valve position 1 (1).

6. The apparatus for determining total hydrocarbons, non-methane hydrocarbons, and benzene series compounds in a gas according to claim 1, characterized in that, include: Second EPC controller (15); the air source is connected to the air inlet pipe of the FID hydrogen flame ionization detector (10), and the second EPC controller (15) is installed on the connecting pipe.

7. The apparatus for determining total hydrocarbons, non-methane hydrocarbons, and benzene series compounds in a gas according to claim 1, characterized in that, include: Nitrogen source, third EPC controller (16); The third EPC controller (16) is installed on the pipeline connecting the nitrogen source and the nitrogen inlet of the FID hydrogen flame ionization detector (10).

8. The apparatus for determining total hydrocarbons, non-methane hydrocarbons, and benzene series compounds in a gas according to claim 1, characterized in that, include: Y-shaped tee (19); The second port of the Y-shaped tee (19) is connected to the pipeline of position 3 (3) of the six-way valve; The first port of the Y-shaped tee (19) is connected to the hydrocarbon removal air passage; The second port of the Y-shaped tee (19) is connected to the sample gas path.

9. The apparatus for determining total hydrocarbons, non-methane hydrocarbons, and benzene series compounds in a gas according to claim 1, characterized in that, include: Two-hole graphite pad; a two-hole graphite pad is installed at the sample outlet of the gas chromatograph; The inlet of the FID flame ionization detector (10) is equipped with a dual-hole graphite pad; One end of the total hydrocarbon separation column (7) is inserted into the double-hole graphite pad at the outlet of the gas chromatograph, and the other end is inserted into the double-hole graphite pad at the inlet of the FID flame ionization detector (10). One end of the methane-benzene separation column (8) is inserted into a two-hole graphite pad on the outlet of the gas chromatograph, and the other end is inserted into a two-hole graphite pad on the inlet of the FID flame ionization detector (10).

10. The apparatus for determining total hydrocarbons, non-methane hydrocarbons, and benzene series compounds in a gas according to claim 9, characterized in that, The methane-benzene separation column (8) is 30 m long, 0.32 mm in inner diameter, and 1 μm thick.

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