Thermal cracking sample injector with sample recycling and reinjection and pollution isolation functions

Abstract

The utility model provides a thermal cracking sample injector with sample recycling and reinjection and pollution isolation functions, which is characterized in that one end of a thermal cracking carrier gas circuit is connected with an external gas source, and the other end of the thermal cracking carrier gas circuit is sequentially connected with a thermal cracking carrier gas electromagnetic valve and a thermal cracking carrier gas pressure controller, is finally connected to a thermal cracking sample injector main body and is communicated with an upper opening of a thermal cracking cavity; a lower opening of the thermal cracking cavity is communicated with a first interface of the three-way interface; a second interface of the three-way interface is connected with a thermal cracking shunting gas circuit, the thermal cracking shunting gas circuit is further bypassed with a recovery pipeline, the thermal cracking shunting gas circuit is used for emptying, and the recovery pipeline is used for recovering and sampling; a third interface of the three-way interface is connected with a thermal cracking sample injection needle, and the thermal cracking sample injection needle is inserted into a gas chromatographic sample injection port provided with a gas chromatographic column; and the gas chromatography sample inlet is also communicated with a gas chromatography carrier gas path and a gas chromatography split-flow gas path.

Description

Technical Field

[0001] This utility model relates to an injector used in gas chromatography and mass spectrometry and related fields, and particularly to a thermal pyrolysis injector. Background Technology

[0002] Pyrolysis is a sample introduction device used in gas chromatography and mass spectrometry. Its main function is to decompose solid samples into vaporized small molecule compounds through instantaneous high temperature, and then introduce them into downstream analytical equipment such as gas chromatography or mass spectrometry. Pyrolysis sample introducers have wide applications in polymer materials, environmental monitoring, biomedicine, catalysis, and petrochemicals.

[0003] Pyrolysis samplers primarily test the composition and additive components of solid samples. Since the concentration of substances in solid samples is the highest among the gas, liquid, and solid states, to avoid contamination and signal overload of downstream analytical equipment due to high concentrations of products generated during solid sample pyrolysis, small sample volumes are generally used for analysis, such as milligrams or even lower micrograms. However, at such milligram / microgram sample volumes, the concentrations of additive components in the gaseous products of pyrolysis, as well as the pyrolysis products of some main components, are extremely low, making them undetectable by downstream analytical equipment. Therefore, it is difficult to achieve a balance between sample matrix contamination and the detection of low-content target analytes. Currently available pyrolysis equipment cannot resolve this contradiction. Furthermore, because pyrolysis is a destructive sampling method, some scarce samples, such as those for legal testing, are consumed after a single run, and since no further samples can be obtained, retesting for confirmation is impossible.

[0004] As described in patent CN210711399U, this method employs a traditional pyrolysis injection method, utilizing gas chromatography carrier gas and split control to achieve both injection and split functions. During injection, a portion of the pyrolysis products are introduced into analytical equipment such as gas chromatography-mass spectrometry, while the remainder is vented through the split port of the gas chromatograph. This traditional pyrolysis injection method fails to provide a suitable solution for low-concentration pyrolysis product analysis sensitivity and sample re-analysis confirmation. Meanwhile, as described in patent CN214252163U, the split injection system features a split pipeline for two-stage splitting, reducing injection volume and system contamination. However, its split section lacks a heating and insulation device, making it prone to sample condensation and blockage. Furthermore, its pyrolysis temperature range is narrow, reaching only 450℃, enabling only thermal desorption and failing to meet the high temperatures required for pyrolysis. It cannot handle solid samples or samples requiring high-temperature pyrolysis for analysis, and it lacks a rapid cooling module, requiring prolonged natural cooling during analysis intervals.

[0005] This utility model relates to a vertical pyrolysis system, which is typically mounted above the gas chromatograph (GC) inlet. The pyrolysis products are directly introduced into the GC or mass spectrometer for analysis via a syringe. After sample introduction or long-term sample processing, the pyrolysis system generally requires high-temperature cleaning to remove residual contaminants from the pyrolysis chamber. During high-temperature cleaning of the pyrolysis system, because it utilizes the carrier gas path of the GC inlet and is mounted above it, residual contaminants discharged at high temperature can also directly enter downstream analytical equipment such as the GC via the pyrolysis syringe, causing further contamination. This is a common situation during high-temperature cleaning of existing vertical pyrolysis syringes. Utility Model Content

[0006] The main purpose of this invention is to solve the sensitivity problem of thermal pyrolysis in the analysis of low-concentration samples, increase the functions of sample recovery, preservation and re-injection analysis, and isolate the thermal pyrolysis injector and the back-end analysis equipment from contamination during high-temperature cleaning.

[0007] The technical means adopted in this utility model are as follows:

[0008] A pyrolysis injector with sample recovery and re-injection and contamination isolation functions, characterized in that it comprises:

[0009] One end of the pyrolysis carrier gas path is connected to an external gas source, and the other end is connected in sequence to the pyrolysis carrier gas solenoid valve and the pyrolysis carrier gas pressure controller, and finally connected to the pyrolysis injector body and connected to the upper opening of the pyrolysis chamber.

[0010] The lower opening of the pyrolysis chamber is connected to the first interface of the tee connector;

[0011] The second port of the three-way interface is connected to the pyrolysis diversion gas path, which is also connected to a recovery pipeline. The pyrolysis diversion gas path is equipped with a pyrolysis vent filter, a pyrolysis vent solenoid valve and a pyrolysis vent flow controller in sequence. The recovery pipeline is equipped with a pyrolysis recovery solenoid valve, a pyrolysis recovery sampling pipe, a pyrolysis recovery flow controller and a recovery sampling pump in sequence.

[0012] The third port of the three-way connector is connected to the pyrolysis injection needle, which is inserted into the gas chromatography injection port containing the gas chromatography column; the gas chromatography injection port is also connected to the gas chromatography carrier gas path and the gas chromatography split gas path.

[0013] The pyrolysis injector with sample recovery and re-injection and contamination isolation functions is provided in the pyrolysis chamber inside the main body of the pyrolysis injector, and a pyrolysis heating module, a pyrolysis cooling module and a pyrolysis heat preservation module are arranged outside the pyrolysis chamber.

[0014] The pyrolysis sampler with sample recovery and re-injection and contamination isolation functions is described above, wherein the pyrolysis chamber is adaptable to the metal sample cup and the pyrolysis recovery sampling tube.

[0015] The pyrolysis injector with sample recovery and re-injection and contamination isolation functions is described above, wherein the three-way interface is equipped with a heating module.

[0016] Technical effects of this utility model:

[0017] 1. The quartz pyrolysis chamber of this invention has a larger capacity than sample injectors on the market, and the pyrolysis temperature can reach 1100℃. It can not only rapidly pyrolyze samples, but also pyrolyze and inject large-volume samples.

[0018] 2. This utility model has a sample recovery function. Through the recovery of thermal pyrolysis and the setting of the venting air path, the products of thermal pyrolysis are recovered and enriched in the thermal pyrolysis recovery sampling tube with packing material, thereby improving the analytical sensitivity of low concentration target substances in the pyrolysis products, and realizing the recovery, preservation and secondary analysis of the sample.

[0019] 3. The three-way interface of this utility model has a thermal decomposition three-way interface heating module, which can ensure that the sample will not condense during the recovery, venting and sample injection process.

[0020] 4. This utility model is equipped with a switch solenoid valve on the recovery pipeline, which can be used to select whether or not to recover the sample.

[0021] 5. The pyrolysis recovery sampling tube of this utility model is a standard thermal desorption sampling tube made of metal or glass with an outer diameter of 1 / 4 inch and a length of 3.5 inches, which can be adapted to the pyrolysis chamber.

[0022] 6. This utility model is equipped with a recovery flow controller on the recovery pipeline, which can quantitatively recover the volume of gas to achieve the purpose of quantitative analysis.

[0023] 7. The quartz pyrolysis chamber of this utility model is adapted to the pyrolysis sample cup and the pyrolysis recovery sampling tube, which can realize the use of a set of pyrolysis injectors to complete the pyrolysis injection and the thermal desorption injection of the recovered sampling tube.

[0024] 8. The pyrolysis venting path is designed to effectively reduce the amount of pyrolysis products entering the pyrolysis injection needle, thereby reducing the risk of clogging of the pyrolysis injection needle.

[0025] 9. This utility model has a filter in the pyrolysis venting air path, which can effectively prevent the sample gas from contaminating the air.

[0026] 10. This invention offers a wider sample loading range. Through pyrolysis recovery and venting pathways, as well as gas chromatography splitting, it achieves greater sample splitting and venting control, thereby accommodating larger injection volumes and reducing system contamination.

[0027] 11. After thermal pyrolysis, the sample of this utility model is directly introduced into the gas chromatograph through the thermal pyrolysis injection needle, without intermediate sample transfer lines, reducing the sample transfer process and effectively solving the problem of contamination residues during sample gas transfer.

[0028] 12. This utility model can effectively prevent contaminants from entering the downstream analysis equipment during the high-temperature cleaning of pyrolysis by simply adjusting the pressure of the pyrolysis carrier gas path and the pressure of the gas chromatography carrier gas.

[0029] 13. This utility model is equipped with a pyrolysis cooling module, which has a rapid cooling function. It can quickly adjust from a high temperature state to a medium or low temperature state, improving work efficiency without waiting for natural cooling. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the thermal decomposition structure of this utility model;

[0031] Figure 2 When no contamination isolation is required, the contaminants generated during the high-temperature cleaning process of pyrolysis enter the spectrum of the analytical equipment;

[0032] Figure 3 This is to ensure that contaminants generated during the high-temperature cleaning process of pyrolysis do not enter the spectrum of the analytical equipment after isolation by carrier gas pressure through pyrolysis and gas chromatography.

[0033] Explanation of reference numerals in the attached figures: 1-Pyrolysis injector body; 11-Pyrolysis chamber; 12-Pyrolysis heating module; 13-Pyrolysis cooling module; 14-Pyrolysis insulation module; 15-Metal sample cup; 2-Pyrolysis carrier gas path; 21-Pyrolysis carrier gas solenoid valve; 22-Pyrolysis carrier gas pressure controller; 3-T-way interface; 31-Pyrolysis T-way interface heating module; 4-Pyrolysis split gas path; 41-Pyrolysis vent filter; 42-Pyrolysis vent solenoid valve; 43-Pyrolysis vent flow controller; 44-Pyrolysis recovery solenoid valve; 45-Pyrolysis recovery sampling tube; 46-Pyrolysis recovery flow controller; 47-Recovery sampling pump; 5-Pyrolysis injection needle; 6-Gas chromatography injection port; 61-Gas chromatography carrier gas path; 62-Gas chromatography split gas path; 7-Gas chromatography column. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0035] like Figure 1 The image shows a preferred embodiment of a pyrolysis injector with sample recovery and re-injection and contamination isolation functions provided by this utility model, wherein:

[0036] One end of the pyrolysis carrier gas path 2 is connected to an external gas source via a gas pipeline, and the other end of the pipeline is connected in sequence to the pyrolysis carrier gas solenoid valve 21 and the pyrolysis carrier gas pressure controller 22, and finally connected to the pyrolysis injector body 1; the pyrolysis injector body 1 is provided with a pyrolysis chamber 11 inside, and a pyrolysis heating module 12, a pyrolysis cooling module 13 and a pyrolysis heat preservation module 14 are arranged on the outside of the pyrolysis chamber 11; the pyrolysis chamber 11 can provide a high-temperature environment with a maximum temperature of 1100℃ for sample pyrolysis;

[0037] The other end of the pyrolysis carrier gas path 2 is connected to the upper opening of the pyrolysis chamber 11. The pyrolysis chamber 11 can be adapted to a conventional metal sample cup 15 and the pyrolysis recovery sampling tube 45 described below. The lower opening of the pyrolysis chamber 11 is connected to the first interface of the three-way interface 3. The three-way interface 3 is equipped with a heating module 31.

[0038] The second port of the three-way interface 3 is connected to the pyrolysis diversion gas path 4. The pyrolysis diversion gas path 4 is also connected to a recovery pipeline. The pyrolysis venting filter 41, the pyrolysis venting solenoid valve 42 and the pyrolysis venting flow controller 43 are sequentially provided on the pyrolysis diversion gas path 4. The pyrolysis recovery solenoid valve 44, the pyrolysis recovery sampling pipe 45, the pyrolysis recovery flow controller 46 and the recovery sampling pump 47 are sequentially provided on the recovery pipeline.

[0039] The third port of the three-way interface 3 is connected to the pyrolysis injection needle 5. The pyrolysis injection needle 5 is inserted into the gas chromatography injection port 6 containing the gas chromatography column 7, thereby realizing the pyrolysis injection to downstream analytical equipment such as gas chromatography-mass spectrometry.

[0040] The gas chromatograph inlet 6 is also connected to the gas chromatograph carrier gas path 61 and the gas chromatograph split gas path 62.

[0041] The following describes its working process:

[0042] 1. During sample testing:

[0043] The pyrolysis carrier gas solenoid valve 21 is opened, and the pressure of the carrier gas is controlled by the pyrolysis carrier gas pressure controller 22. This pressure is adjusted to be higher than the pressure of the gas chromatography carrier gas path 61, such as 60 kPa and above.

[0044] The thermal decomposition carrier gas enters the thermal decomposition chamber 11 at a set high temperature. The sample placed in the metal sample cup 15 undergoes a decomposition reaction and generates vaporized decomposition products. The thermal decomposition carrier gas carries the decomposition products out of the thermal decomposition chamber 11 and into the three-way interface 3.

[0045] In the three-way interface 3 with heating module 31, the pyrolysis carrier gas and pyrolysis products are divided into three parts:

[0046] The first part of the gas is controlled by the pyrolysis venting solenoid valve 42 and the pyrolysis venting flow controller 43. The flow rate ranges from 0 ml / min to 1000 ml / min and is eventually vented. In order to avoid the harmful substances in the pyrolysis products from polluting the environment, the gas will first pass through the pyrolysis venting filter 41 to adsorb and remove the pyrolysis products before entering the pyrolysis venting solenoid valve 42.

[0047] The second part of the gas is controlled by the thermal decomposition recovery solenoid valve 44 to determine whether it is to be recovered. If recovery is required, it passes through the thermal decomposition recovery solenoid valve 44, the thermal decomposition recovery sampling tube 45, the thermal decomposition recovery flow controller 46 and the sampling pump 47 in sequence to quantitatively recover and enrich the gas in the thermal decomposition recovery sampling tube 45.

[0048] The final portion of the pyrolysis carrier gas and pyrolysis products enters the pyrolysis injection needle 5 through the gas path three-way interface 3 and is introduced into the gas chromatography injection port 6. In the gas chromatography injection port 6, the carrier gas in the gas chromatography carrier gas path 61 introduces the pyrolysis carrier gas and pyrolysis products into the gas chromatography split gas path 62 and the gas chromatography column 7, respectively, to complete the pyrolysis injection analysis.

[0049] During this test, the pyrolysis recovery solenoid valve 44 and the pyrolysis recovery flow controller 46 are adjusted to quantitatively recover and enrich the pyrolysis product gas. The recovered sampling tube 45 can then be used with this pyrolysis sampler for secondary desorption injection. Because sample enrichment occurs during the recovery process, high-sensitivity detection of low-concentration target analytes in the pyrolysis products can be achieved. The pyrolysis recovery sampling tube 45 also recovers and preserves the pyrolysis products of the sample, allowing for secondary analysis and result confirmation.

[0050] During this test, the pyrolysis split gas path 4 independently vented the pyrolysis product gas through the pyrolysis vent solenoid valve 42 and the pyrolysis vent flow controller 43. Combined with the downstream gas chromatography split gas path 62, it achieved a wider range of split control, thereby adapting to a wider range of sample loading and reducing system contamination.

[0051] 2. High-temperature cleaning via pyrolysis:

[0052] The pyrolysis carrier gas solenoid valve 21 is opened, and the pressure of the carrier gas is controlled by the pyrolysis carrier gas pressure controller 22. This pressure is adjusted to be higher than the pressure of the gas chromatography carrier gas path 61, such as 40-50 kPa.

[0053] The pyrolysis carrier gas enters the pyrolysis chamber 11 at a set high temperature. The high temperature causes the contaminants in the pyrolysis chamber 11 to vaporize. The pyrolysis carrier gas carries the vaporized contaminants out into the three-way port 3. Under the pressure balance damping of the gas chromatography carrier gas path 61, the pyrolysis carrier gas and vaporized contaminants cannot enter the gas chromatography inlet 6. They can only pass through the pyrolysis vent filter 41 of the pyrolysis split gas path 4 and flow out from the pyrolysis vent solenoid valve 42 and the pyrolysis vent flow controller 43, which are in the open state, and then vent.

[0054] During this cleaning process, the contaminants generated by the high-temperature cleaning and baking of pyrolysis are directly discharged from the outlet of the pyrolysis split gas path 4, avoiding contamination of downstream analytical equipment such as the gas chromatograph inlet 6.

[0055] like Figure 2 and Figure 3 The images show the spectra of pollutants generated by high-temperature cleaning through pyrolysis entering the gas chromatography-mass spectrometry (GC-MS) spectrum without being isolated, and the spectra of pollutants generated by high-temperature cleaning not entering the GC-MS spectrum after isolation through pressure balancing of pyrolysis and GC. The results show that pressure balancing through pyrolysis and GC has a significant pollution isolation effect.

[0056] During testing or cleaning, the thermal pyrolysis heating module 12 and / or thermal pyrolysis cooling module 13 can be controlled to quickly switch between different operating temperatures of the thermal pyrolysis chamber 11, with a temperature switching range from 25°C to 1100°C. Therefore, it is not necessary to wait for natural cooling at high temperatures before conducting sample testing at the next temperature.

[0057] Rapid cooling – When the thermal pyrolysis or thermal desorption work is completed, and it is necessary to carry out the next stage of thermal pyrolysis or thermal desorption work at a lower temperature than the previous stage as soon as possible, this thermal pyrolysis injector will automatically start the thermal pyrolysis cooling module 13 to perform rapid cooling operation, thereby improving the efficiency of switching between different temperatures.

[0058] Rapid heating – When high-temperature pyrolysis is required, the thermal pyrolysis heating module 12 can be controlled to quickly reach a high-temperature working state.

Claims

1. A pyrolysis sampler with sample recovery and re-injection functions and contamination isolation functions, characterized in that, include: One end of the pyrolysis carrier gas path is connected to an external gas source, and the other end is connected in sequence to the pyrolysis carrier gas solenoid valve and the pyrolysis carrier gas pressure controller, and finally connected to the pyrolysis injector body and connected to the upper opening of the pyrolysis chamber. The lower opening of the pyrolysis chamber is connected to the first interface of the tee connector; The second port of the three-way interface is connected to the pyrolysis diversion gas path, which is also connected to a recovery pipeline. The pyrolysis diversion gas path is equipped with a pyrolysis vent filter, a pyrolysis vent solenoid valve and a pyrolysis vent flow controller in sequence. The recovery pipeline is equipped with a pyrolysis recovery solenoid valve, a pyrolysis recovery sampling pipe, a pyrolysis recovery flow controller and a recovery sampling pump in sequence. The third port of the three-way connector is connected to the pyrolysis injection needle, which is inserted into the gas chromatography injection port containing the gas chromatography column; the gas chromatography injection port is also connected to the gas chromatography carrier gas path and the gas chromatography split gas path.

2. The pyrolysis sampler with sample recovery and re-injection and contamination isolation functions according to claim 1, characterized in that, The pyrolysis injector body has a pyrolysis chamber inside, and a pyrolysis heating module, a pyrolysis cooling module, and a pyrolysis heat preservation module are arranged outside the pyrolysis chamber.

3. The pyrolysis sampler with sample recovery and re-injection and contamination isolation functions according to claim 1, characterized in that, The pyrolysis chamber is compatible with metal sample cups and the pyrolysis recovery sampling tube.

4. The pyrolysis sampler with sample recovery and re-injection and contamination isolation functions according to claim 1, characterized in that, The three-way connector is equipped with a heating module.

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