Chromatographic detection method

Abstract

The invention relates to the technical field of chromatographic analysis, and particularly provides a chromatographic detection method. The chromatographic detection method comprises the following steps: (1) sample introduction: respectively introducing samples at different detection points into a sample introduction part with a switching valve through a plurality of sample introduction channels, and switching the sample introduction of each sample through the switching valve; (2) distribution: distributing the samples to different detection branches through a switching valve according to the types of the samples from the sample introduction part; (3) pretreatment: carrying out different pretreatments on the sample in different detection branches; and (4) detection: detecting the pretreated sample. The chromatographic detection method provided by the invention is used for sampling, analyzing and detecting a plurality of sampling point positions and samples with different phase states in the same process place.

Description

Technical Field

[0001] The present disclosure relates to the technical field of chromatography analysis, and in particular to a chromatography detection method. Background Art

[0002] In industrial production process control, in order to timely grasp the process status of the production equipment, sampling ports are set on the process pipelines and equipment to analyze the phase composition in the detection system. The entire process of process detection has the problem of multiple analysis points and different sample phases.

[0003] At present, sampling is generally done manually, such as using high-pressure gas cylinders to take gaseous and volatile media, and using ordinary glass or plastic containers to take liquid media. This method is time-consuming and labor-intensive, with low detection efficiency, and is time-delayed for the application of data to guide process production. Alternatively, analysis cabins are built at different locations, and different sampling, processing systems and detection equipment are used according to the status of different materials. This requires more public works and materials, and is costly. Summary of the invention

[0004] The present disclosure is proposed in view of the above problems. The present disclosure provides a chromatographic detection method, which can perform sampling analysis and detection on multiple sampling points and samples of different phases in the same process site.

[0005] According to one aspect of the present disclosure, a chromatographic detection method is provided, comprising the following steps:

[0006] (1) Injection: Samples at different detection points are introduced into an injection section having a switching valve through a plurality of injection channels, and the injection of each sample is switched by the switching valve;

[0007] (2) Allocation: Allocation of the sample to different detection branches by switching valves according to the type of the sample from the sample injection section;

[0008] (3) Pretreatment: performing different pretreatments on the sample in different detection branches;

[0009] (4) Detection: Detecting the sample after the pretreatment.

[0010] Compared with the prior art, the chromatographic detection method provided by the present invention has the following advantages:

[0011] In the chromatographic detection method provided by the embodiment of the present invention, first, the target sampling point to be detected can be connected with the corresponding sample sampling port of the sampling valve, and the target sampling point to be detected can be sampled by using the sampling valve, and the samples at different detection points are respectively introduced into the sampling part with the switching valve through multiple injection channels, and the injection of each sample is switched by the switching valve. Sampling of multiple sampling points in the same process site is achieved. Secondly, according to the type of sample from the injection part, the sample is distributed to different detection branches by the switching valve. For example: if the target sample to be detected is a gas medium, the switching valve can be connected to the first branch to transport the target sample to be detected to the first branch; if the target sample to be detected is a volatile medium, the switching valve can be connected to the second branch to transport the target sample to be detected to the second branch. If the target sample to be detected is a liquid medium, the switching valve is connected to the third branch to transport the target sample to be detected to the third branch. Then, the sample is pretreated differently in different detection branches. Finally, the pretreated sample is detected. The target sample to be detected after pretreatment by the first branch or the second branch is transported to the first detection device for detection, and the target sample to be detected after pretreatment by the third branch is transported to the second detection device for detection. Therefore, sampling, analysis and detection of multiple sampling points and samples of different phases are realized in the same process site. The same integrated system can simultaneously meet the needs of gas, volatile liquid and liquid sampling and analysis, saving space layout and investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other purposes, features and advantages of the present disclosure will become more apparent by describing the embodiments of the present disclosure in more detail in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the present disclosure and do not constitute a limitation of the present disclosure. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0013] Figure 1 is a flow chart of the chromatographic detection method of an embodiment of the present disclosure;

[0014] Figure 2 is a process flow chart of a chromatographic detection system provided by an embodiment of the present disclosure;

[0015] Figure 3 is a schematic diagram of the structure of a sampling valve provided in an embodiment of the present disclosure;

[0016] Figure 4 is a schematic diagram of a switching valve according to an embodiment of the present disclosure;

[0017] Figure 5 It is a schematic diagram of the structure of the flash tank of an embodiment of the present disclosure.

[0018] Reference numerals:

[0019] 100-sampling valve, 110-sample sampling inlet, 120-sample outlet, 200-switching valve, 210-first outlet of the switching valve, 220-second outlet of the switching valve, 230-third outlet of the switching valve, 300-first branch, 310-first flow pressure reducing valve, 400-second branch, 410-second flow pressure reducing valve, 420-flash tank, 430-first three-way valve, 430a-first inlet of the first three-way valve, 430b-second inlet of the first three-way valve, 440-second three-way valve, 440a-first outlet of the second three-way valve, 440b-second outlet of the second three-way valve, 450-gas injection Quantitative valve, 451-first carrier gas inlet, 460-insulated two-way, 500-third branch, 510-flow regulating valve, 520-trace liquid injection valve, 521-liquid vent outlet, 522-second carrier gas inlet, 530-third one-way valve, 600-first detection device, 700-second detection device; 800-first gas vent flow path, 810-flow meter, 820-first back pressure valve, 830-first one-way valve, 900-second gas vent flow path, 910-second back pressure valve, 920-second one-way valve, 1000-inert gas purge unit, 1100-filter, 1200-equipment root valve. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present disclosure more obvious, the exemplary embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments of the present disclosure, and it should be understood that the present disclosure is not limited to the exemplary embodiments described here.

[0021] In industrial production process control, in order to timely grasp the process status of the production equipment, sampling ports will be set on the process pipelines and equipment to analyze the phase composition in the detection system. The entire process of process detection has many analysis points and different sample states. For example, in the production process of synthesizing liquefied natural gas from coke oven gas, it is necessary to timely understand the composition of methane, carbon monoxide, carbon dioxide, hydrogen, and nitrogen in the raw gas and production process gas, and it is also necessary to test the composition of liquefied natural gas and liquid refrigerant composition changes. In the production process of methanol to olefins, it is necessary to detect the composition of materials in different phases such as raw methanol and product olefins.

[0022] Gas chromatography is often used for material composition analysis in the above-mentioned production process. Gas chromatography separation and detection technology for various materials is relatively mature. At present, the main links that affect the efficiency and accuracy of material analysis and detection are sampling and pre-treatment processes. Generally, sampling is done manually, such as using high-pressure gas cylinders to take gaseous media and volatile media, and using ordinary glass or plastic containers to hold liquid media. This method is time-consuming and labor-intensive, with low detection efficiency, and time lags for the application of data to guide process production. Alternatively, analysis cabins can be built in different locations, and different sampling, processing systems and detection equipment can be adopted according to the status of different materials. This requires more public works and materials, and the cost is relatively high.

[0023] In view of the above problems, the embodiments of the present disclosure provide a chromatographic detection method, which can perform sampling, analysis and detection on multiple sampling points and samples of different phases in the same process site. The problems of time-consuming and labor-intensive manual sampling and low efficiency, large space occupation and high cost when establishing chromatographic analysis systems at different sampling points in the prior art are solved.

[0024] Figure 1 The flowchart of the chromatographic detection method of the embodiment of the present disclosure is shown, which is applied to the chromatographic detection system of the embodiment of the present disclosure. Figure 1 As shown, the chromatographic detection method of the embodiment of the present disclosure includes:

[0025] Step 100: Injection: Samples at different detection points are introduced into an injection part having a switching valve through a plurality of injection channels, and the injection of each sample is switched by the switching valve.

[0026] For example, first, the target sampling point to be detected can be connected to the corresponding sample sampling inlet of the sampling valve, and the sampling valve can be used to sample the target sampling point to be detected, and the samples at different detection points can be introduced into the sampling part with the switching valve through multiple injection channels, and the injection of each sample can be switched through the switching valve. Sampling at multiple sampling points in the same process site is achieved.

[0027] Step 200: Distribution: Distribute the sample to different detection branches through a switching valve according to the type of the sample from the sample injection part.

[0028] In one achievable manner, the types of samples in the embodiments of the present disclosure include: gas medium, volatile medium, and liquid medium.

[0029] It should be noted that the gas medium described in the present disclosure refers to a sample in which all components are in a gaseous state at the process or experimental temperature and pressure, for example, nitrogen, carbon monoxide, carbon dioxide, and a methane mixture, but not limited thereto. The volatile medium described in the present disclosure refers to a sample in which the components are a liquid mixture at the process or experimental temperature and pressure, and a gas-liquid mixture at normal temperature and pressure, and a sample with a wide boiling range distribution, for example, liquefied petroleum gas, hydrocarbons with a carbon number of less than 8, and mixtures thereof, but not limited thereto. The liquid medium described in the present disclosure refers to a sample in which the components have a relatively high boiling point and are all liquid at normal temperature and pressure, for example, alcohols such as methanol and ethanol, gasoline, and diesel, but not limited thereto. In addition, although the above definitions of the three types of samples are given in this application, the classification of the relevant samples can be adjusted as needed. For example, a mixture of methane and alcohols can be divided into different types according to the methane content. Specifically, if the methane content is high and the sample is in a gaseous state as a whole, the sample type can be classified as a gas medium. If the methane and alcohol contents are equivalent, the sample type can be classified as a volatile medium. If the alcohol content is high and the sample is in a liquid state as a whole, the sample type can be classified as a liquid medium.

[0030] For example, if the target sample to be detected is a gas medium, the switching valve can be connected to the first branch to deliver the target sample to be detected to the first branch; if the target sample to be detected is a volatile medium, the switching valve can be connected to the second branch to deliver the target sample to be detected to the second branch. If the target sample to be detected is a liquid medium, the switching valve can be connected to the third branch to deliver the target sample to be detected to the third branch.

[0031] Step 300: Preprocessing: performing different preprocessing on the sample in different detection branches.

[0032] Exemplarily, if the target sample to be detected is a gas medium, the target sample to be detected entering the first branch can be pre-treated. If the target sample to be detected is a volatile medium, the target sample to be detected entering the second branch can be pre-treated. If the target sample to be detected is a volatile liquid medium, the target sample to be detected entering the third branch can be pre-treated.

[0033] Step 400: Detection: Detecting the pre-treated sample.

[0034] Exemplarily, the target sample to be detected after pre-processing by the first branch or the second branch is transported to the first detection device for detection, and the target sample to be detected after pre-processing by the third branch is transported to the second detection device for detection.

[0035] Therefore, it is possible to perform sampling analysis and testing on multiple sampling points and samples of different phases in the same process site. The same integrated system can simultaneously meet the needs of gas, volatile liquid and liquid sampling analysis, saving space layout and investment.

[0036] In an optional manner, the above-mentioned different pretreatments of the sample in different detection branches specifically include: when the type of the sample is a gas medium, the sample is introduced into a first detection branch having a pressure reducing valve, and the pretreatment includes decompressing the sample. When the type of the sample is a volatile medium, the sample is introduced into a second detection branch having a pressure reducing valve and a flash tank, and the pretreatment includes decompressing the sample and flashing the sample. When the type of the sample is a liquid medium, the sample is introduced into a third detection branch having a flow regulating valve and a micro-liquid injection valve, and the pretreatment includes flow regulating the sample and micro-injection of the sample.

[0037] Exemplarily, when the type of the sample is a gas medium, the sample is introduced into a first detection branch having a pressure reducing valve, and the pretreatment includes decompressing the sample. Specifically, the gas medium is decompressed using a first flow pressure reducing valve. The target gas medium to be detected after the decompression treatment is sequentially delivered to the first three-way valve, the second three-way valve and the gas sampling quantitative valve for quantitative sampling, and then the gas in the sampling valve is delivered to the first detection device.

[0038] Exemplarily, when the type of the sample is a volatile medium, the sample is introduced into a second detection branch having a pressure reducing valve and a flash tank, and the pretreatment includes performing a pressure reducing treatment on the sample and performing a flash evaporation treatment on the sample. Specifically, it includes: performing a pressure reducing treatment on the volatile medium using a second flow pressure reducing valve, and delivering the volatile medium after the pressure reducing treatment to a flash tank for flash evaporation treatment. The volatile medium after the flash evaporation treatment is sequentially delivered to the first three-way valve, the second three-way valve and the gas sampling quantitative valve for quantitative injection, and then the gas in the injection valve is delivered to the first detection device.

[0039] Exemplarily, when the sample type is a liquid medium, the sample is introduced into a third detection branch having a flow control valve and a micro-liquid injection valve, and the pretreatment includes flow control treatment of the sample and micro-injection treatment of the sample. Specifically, it includes: using the flow control valve to control the flow of the liquid medium, then delivering the flow-regulated liquid medium to the micro-liquid injection valve for quantitative injection, and then delivering the quantitative liquid medium to the second detection device.

[0040] In one achievable manner, the chromatographic detection method of the embodiment of the present disclosure further includes: when the type of the sample is a gas medium, after the sample is subjected to a decompression treatment, the pretreatment further includes replacing the sample using a first vent branch.

[0041] Exemplarily, the above-mentioned sample replacement using the first venting branch specifically includes: if the target sample to be detected is a gas medium, before detecting the target sample to be detected, connecting the second three-way valve and the first gas venting flow path to vent the gas medium.

[0042] For example, if the target sample to be detected is a gas medium, before detecting the target sample to be detected, the second three-way valve, the flow meter, the first back pressure valve and the first one-way valve are connected to discharge the gas medium.

[0043] In one achievable manner, the chromatographic detection method of the embodiment of the present disclosure further includes: when the type of the sample is a volatile medium, after the sample is subjected to a decompression treatment and a flash evaporation treatment, the pretreatment further includes performing sample replacement on the sample using a first vent branch.

[0044] Exemplarily, the above-mentioned sample replacement using the first venting branch specifically includes: if the target sample to be detected is a volatile medium, before detecting the target sample to be detected, connecting the second three-way valve and the first gas venting flow path to vent the volatile medium.

[0045] For example, if the target sample to be detected is a volatile medium, before detecting the target sample to be detected, the second three-way valve, the flow meter, the first back pressure valve and the first check valve are connected to discharge the volatile medium.

[0046] In one achievable manner, the chromatographic detection method of the embodiment of the present disclosure further includes: when the type of the sample is a gas medium or a volatile medium, after the sample is introduced into a second detection branch having a gas injection quantitative valve, the pressure in the gas injection quantitative valve is adjusted using a second vent branch.

[0047] Exemplarily, the above-mentioned use of the second vent branch to regulate the pressure in the gas sampling quantitative valve specifically includes: if the pressure in the gas sampling quantitative valve is high, the pressure in the gas sampling quantitative valve is vented after the gas sampling quantitative valve, the second back pressure valve and the second one-way valve are connected in sequence.

[0048] In one achievable manner, the chromatographic detection method of the embodiment of the present disclosure further includes: when the type of the sample is a liquid medium, after the sample is introduced into the third detection branch, the third vent branch is used to discharge excess sample in the trace liquid injection valve.

[0049] In one achievable manner, the chromatographic detection method of the embodiment of the present disclosure further includes: inert gas purging: before or after injection, the multiple injection channels are purged with an inert gas.

[0050] Exemplarily, the chromatographic detection method of the embodiment of the present disclosure further includes: filtration: filtering the sample through a filter before or after injection.

[0051] Figure 2 The process flow chart of the chromatographic detection system provided by the embodiment of the present disclosure is shown. When applied to a place with multiple sampling points to be detected, it is possible to implement sample sampling and analysis for multiple sampling points in the same process place. Figure 3 FIG. 2 shows a schematic diagram of the structure of a sampling valve provided by an embodiment of the present disclosure. Figure 2 and Figure 3 As shown, the chromatographic detection system of the embodiment of the present disclosure includes: a sampling valve 100, a switching valve 200, a first branch 300, a second branch 400, a third branch 500, a first detection device 600 and a second detection device 700. The sampling valve 100 has multiple injection channels, each of which has a sample sampling inlet 110 and a sample outlet 120. The multiple sample sampling inlets 110 are respectively connected to the corresponding sampling points to be detected, and the sample outlet 120 is connected to the inlet of the switching valve 200. The switching valve 200 includes a first outlet 210, a second outlet 220 and a third outlet 230. The first outlet 210 of the switching valve 200 is connected to the first branch 300, the second outlet 220 of the switching valve 200 is connected to the second branch 400, and the third outlet 230 of the switching valve 200 is connected to the third branch 500. Among them, the outlet of the first branch 300 and the outlet of the second branch 400 are respectively connected to the first detection device 600, and the outlet of the third branch 500 is connected to the second detection device 700.

[0052] It is understandable that the number of the multiple sample inlets 110 of the sampling valve 100 can be 4 to 16, which can be selected according to needs and is not limited here. Therefore, during the analysis process, the multiple sample inlets 110 can be connected to multiple target sampling points to be detected, and the sample of a target sampling point to be detected can be selected manually or program-controlled to enter the sampling system and then enter the chromatogram for analysis.

[0053] The first branch 300 is a gas medium sampling flow path, the second branch 400 is a volatile medium sampling flow path, and the third branch 500 can be a liquid medium sampling flow path. Among them, the volatile liquid refers to a gas-liquid mixture with a wide boiling point range of the main component at normal temperature and pressure, such as liquefied natural gas (-164℃~125℃, methane~octane).

[0054] The first detection device 600 may be a gas chromatograph, and the second detection device 700 may include a gasification device and a gas chromatograph. The liquid coming out of the third flow path 500 may enter the gasification device of the second detection device 700 to be converted into gas, and the gas then enters the gas chromatograph for detection.

[0055] Figure 4 Schematic diagram of a switching valve according to an embodiment of the present disclosure is shown. Figure 4 As shown, the switching valve 200 may be a one-inlet and three-outlet valve, so that the first branch 300 , the second branch 400 , the third branch 500 and the target sample to be detected can be connected through the switching valve 200 .

[0056] In specific implementation, when it is necessary to sample and analyze the target sampling point to be detected, first, the target sampling point to be detected can be connected to the corresponding sample collection port 110 of the sampling valve 100, and the sampling valve 100 can be used to sample the target sampling point to be detected, and the collected target sample to be detected can be delivered to the switching valve 200 through the sample outlet 120 of the sampling valve 100. At this time, if the target sample to be detected is a gas medium, the switching valve 200 can be connected to the first branch 300, and the target sample to be detected can be delivered to the first detection device 600 for detection by using the first branch 300; if the target sample to be detected is a volatile medium, the switching valve 200 can be connected to the second branch 400, and the target sample to be detected can be delivered to the first detection device 600 for detection by using the second branch 400; if the target sample to be detected is a liquid medium, the switching valve 200 can be connected to the third branch 500, and the target sample to be detected can be delivered to the second detection device 700 for detection by using the third branch 500. Therefore, it is possible to perform sampling analysis and testing on multiple sampling points and samples of different phases in the same process site. The same integrated system can simultaneously meet the needs of gas, volatile liquid and liquid sampling analysis, saving space layout and investment.

[0057] In one achievable manner, the first branch 300 of the embodiment of the present disclosure includes a first flow pressure reducing valve 310 , and the first outlet 210 of the switching valve 200 is in communication with an inlet of the first flow pressure reducing valve 310 .

[0058] In specific implementation, if the target sample to be detected is a gas medium, the switching valve 200 is connected to the first flow pressure reducing valve 310, and the first flow pressure reducing valve 310 is used to transport the target sample to be detected to the first detection device 600 for detection.

[0059] Exemplarily, the second branch 400 of the embodiment of the present disclosure includes a second flow pressure reducing valve 410, a flash tank 420 and a first three-way valve 430, a second three-way valve 440 and a gas sampling quantitative valve 450, the second outlet 220 of the switching valve 200 is connected to the inlet of the second flow pressure reducing valve 410, the outlet of the second flow pressure reducing valve 410 is connected to the inlet of the flash tank 420, the outlet of the flash tank 420 is connected to the first inlet 430a of the first three-way valve 430, the outlet of the first three-way valve 430 is connected to the second three-way valve 440, the first outlet 440a of the second three-way valve 440 is connected to the inlet of the gas sampling quantitative valve 450, and the first outlet of the gas sampling quantitative valve 450 is connected to the first detection device 600.

[0060] It should be understood that the gas sampling quantitative valve 450 can be a six-way sampling valve, which is provided with a quantitative loop for quantitatively introducing gas into the chromatogram, and the quantitative loop volume is the sample volume entering the chromatogram injection port. The quantitative loop volume is preferably 50ul to 5000ul, and more preferably 50ul to 2000ul.

[0061] In a specific implementation, after sampling the target sample to be detected, if the target sample to be detected is a volatile medium, first, the switching valve 200 is connected to the second flow pressure reducing valve 410, and the target volatile medium is transported to the flash tank 420 by using the second flow pressure reducing valve 410; then, the flash tank 420 is used to flash evaporate the target sample to be detected, so that the target sample to be detected is converted into gas; then, the gas is sequentially transported to the first three-way valve 430, the second three-way valve 440 and the gas sampling quantitative valve 450 for sampling and quantitative injection; finally, the quantified gas is transported to the first detection device 600 for detection.

[0062] In an optional manner, the outlet of the first flow pressure reducing valve 310 of the embodiment of the present disclosure is communicated with the second inlet 430 b of the first three-way valve 430 .

[0063] In a specific implementation, the first flow pressure reducing valve 310 can be used to sequentially deliver the target sample to be detected to the first three-way valve 430 , the second three-way valve 440 and the gas sampling quantitative valve 450 for sampling and quantitative measurement.

[0064] In one example, Figure 5 The schematic diagram of the structure of the flash tank of the embodiment of the present disclosure is shown as follows: Figure 5 As shown, both ends of the flash tank 420 of the embodiment of the present disclosure are conical, and the cone angle α of the cone is less than 60°, which can reduce the problems of long replacement time and inaccurate analysis caused by sample residue during sample replacement.

[0065] Exemplarily, the volume of the flash tank 420 of the embodiment of the present disclosure is 10 ml to 50 ml, and more preferably 20 ml, so as to ensure sufficient vaporization space and heat capacity, avoid excessive increase in replacement time, and improve analysis efficiency.

[0066] In an optional manner, a heat-insulating double-pass 460 is further provided between the second flow pressure reducing valve 410 and the flash tank 420 of the embodiment of the present disclosure. The heat-insulating double-pass 460 is made of a heat-insulating material (such as PEEK or PTFE), thereby preventing the sample from being unevenly vaporized due to heat conduction before entering the flash tank 420.

[0067] Illustratively, the chromatographic detection system of the embodiment of the present disclosure further includes a first gas venting flow path 800 , and the second outlet 440 b of the second three-way valve 440 is connected to the inlet of the first gas venting flow path 800 .

[0068] In specific implementation, if the target sample to be detected is a gas medium or a volatile medium, before detecting the target sample to be detected, the second three-way valve 440 and the first gas venting flow path 800 are connected to vent and replace the gas medium or volatile medium. Thus, the impurity gas and air in the first branch or the second branch can be emptied, so that the data obtained by analysis and the gas composition or liquid composition can be found more accurately.

[0069] In one example, the first gas venting flow path 800 of the embodiment of the present disclosure includes a flow meter 810, a first back pressure valve 820 and a first check valve 830, the second outlet 440b of the second three-way valve 440 is connected to the inlet of the flow meter 810, the outlet of the flow meter 810 is connected to the inlet of the first back pressure valve 820, the inlet of the first back pressure valve 820 is connected to the inlet of the first check valve 830, and the outlet of the first check valve 830 is connected to the external space.

[0070] In specific implementation, if the target sample to be detected is a gas medium or a volatile medium, before detecting the target sample to be detected, the second three-way valve 440, the flow meter 810, the first back pressure valve 820 and the first check valve 830 are connected in sequence to vent the gas medium or the volatile medium. In this way, the impurity gas and air in the first branch or the second branch can be emptied, so that the data obtained by analysis and the gas composition or liquid composition can be found more accurately. It should be understood that the first check valve 830 can prevent the abnormal pressure of the venting pipeline from causing backflow.

[0071] It is understandable that the pressure value of the first back pressure valve 820 is 100 kPa to 300 kPa. Setting the pressure within this range can avoid the size of the first back pressure valve 820 affecting the pressure in the flash tank 420 to a certain extent.

[0072] Illustratively, the chromatographic detection system of the embodiment of the present disclosure further includes a second gas venting flow path 900 , the gas sampling quantitative valve 450 has a first carrier gas inlet 451 , and the second outlet of the gas sampling quantitative valve 450 is connected to the second gas venting flow path 900 .

[0073] In specific implementation, if the pressure in the gas sampling quantitative valve 450 is greater than or less than the pressure in the first carrier gas inlet 451, the gas sampling quantitative valve 450 is connected to the second gas venting flow path 900. Therefore, the pressure in the gas sampling quantitative valve 450 and the pressure in the first carrier gas inlet 451 can be set to the same value, so that the pressure value in the quantitative loop is constant, thereby achieving constant mass, ensuring the repeatability of chromatographic injection, and minimizing the system pressure fluctuation during the switching process of the second three-way valve 440.

[0074] In an optional manner, the second gas venting flow path 900 of the embodiment of the present disclosure includes a second back pressure valve 910 and a second one-way valve 920, the second outlet of the gas sampling quantitative valve 450 is connected to the inlet of the second back pressure valve 910, the outlet of the second back pressure valve 910 is connected to the inlet of the second one-way valve 920, and the outlet of the second one-way valve 920 is connected to the external space.

[0075] In specific implementation, if the pressure in the gas sampling quantitative valve 450 is greater than or less than the pressure in the first carrier gas inlet 451, the gas sampling quantitative valve 450, the second back pressure valve 910 and the second check valve 920 are sequentially connected. Thus, the excess pressure in the gas sampling quantitative valve 450 can be released, and the pressure in the gas sampling quantitative valve 450 and the second three-way valve 440 is kept the same, thereby reducing the system pressure fluctuation during the switching process of the second three-way valve 440.

[0076] In an optional manner, the third branch 500 of the embodiment of the present disclosure includes a flow regulating valve 510 and a micro-liquid injection valve 520, the third outlet 230 of the switching valve 200 is connected to the inlet of the flow regulating valve 510, the outlet of the flow regulating valve 510 is connected to the inlet of the micro-liquid injection valve 520, and the first outlet of the micro-liquid injection valve 520 is connected to the second detection device 700. The micro-liquid injection valve 520 is used for injection analysis of liquid media.

[0077] In specific implementation, if the target sample to be detected is a liquid medium, the switching valve 200 is connected to the flow regulating valve 510 and the micro-liquid injection valve 520 in sequence for quantitative injection, and the quantitative liquid medium is transported to the second detection device 700 for detection.

[0078] Exemplarily, the micro-liquid injection valve 520 of the disclosed embodiment further has a liquid vent outlet 521 and a second carrier gas inlet 522, and the liquid vent outlet 521 is also connected to the outside through a third one-way valve 530. The third one-way valve 530 can prevent abnormal pressure in the vent pipe from causing backflow.

[0079] In a specific implementation, when the pressure of the trace liquid injection valve 520 is greater than the second carrier gas inlet 522 , the sample in the trace liquid injection valve 520 is emptied by using the liquid venting outlet 521 .

[0080] Exemplarily, the pressures of the first carrier gas inlet 451 and the second carrier gas inlet 522 may be set to the same pressure, thereby further reducing fluctuations during the switching process of the second three-way valve 440 .

[0081] In one example, the chromatographic detection system of the embodiment of the present disclosure further includes an inert gas purge unit 1000, which is connected to the sampling valve 100. Before each sampling, the sampling valve 100 can be purged and replaced by the inert gas purge unit 1000 to reduce the cross contamination of samples between two analyses. Among them, the inert gas can be selected from nitrogen, helium, argon or other inert gases, which are not limited here.

[0082] Exemplarily, the chromatographic detection system of the embodiment of the present disclosure further includes a filter 1100, the inlet of the filter 1100 is connected to the sampling point to be detected, the outlet of the filter 1100 is connected to the inlet of the sampling valve 100, and the filter 1100 includes a primary filter unit and a secondary filter unit, the filter pore size of the primary filter unit is 8μm to 10μm, and the filter pore size of the secondary filter unit is 1μm to 2μm. The setting of the filter 1100 can effectively prevent the subsequent sample pipeline from being blocked and prevent the wear of the valve parts.

[0083] In one example, the flash tank 420, the first three-way valve 430, the second three-way valve 440, and the gas injection quantitative valve 450 of the embodiment of the present disclosure are placed in the same heating zone, and the heating zone provides vaporization heat for the flash vaporizer and ensures that the vaporized sample does not condense in the injection system. The temperature of the heating zone can be set according to the actual sample boiling point distribution, preferably 80°C to 200°C, more preferably 80°C to 120°C.

[0084] Illustratively, all valves in the chromatographic detection system of the embodiment of the present disclosure can be manually switched on and off or controlled by a program.

[0085] For example, the chromatographic detection system of the embodiment of the present disclosure further includes a plurality of device root valves 1200 , which are respectively arranged at the sample outlets of each sampling point to be detected, and each device root valve 1200 is respectively connected to the filter 1100 .

[0086] Illustratively, the pipelines, valves, flash tanks, etc. (except the venting pipeline) between the sampling port and the chromatographic injection port of all process equipment or samplers in the embodiments of the present disclosure are made of passivated stainless steel materials, which can prevent samples containing active components such as sulfur, oxygen, and ammonia from being adsorbed during the injection process, thereby reducing the accuracy of the analysis.

[0087] Embodiment 1

[0088] The disclosed embodiment provides a process for volatile sample injection (first branch), such as the detection of the composition of the coke oven gas synthesis natural gas raw material: the main components of the coke oven gas synthesis natural gas raw material gas are hydrogen, carbon monoxide, carbon dioxide, nitrogen, methane, ethane, a small amount of propane and butane, all of which are in gas state at room temperature and normal pressure. The specific operation steps are as follows:

[0089] Set the temperature of the heating zone to 80°C, and wait for the temperature of the heating zone to stabilize. First, adjust the first three-way valve so that its inlet end is connected to the first flow pressure reducing valve and its outlet end is connected to the second three-way valve. Further, adjust the second three-way valve so that its inlet end is connected to the first three-way valve and its outlet end is connected to the flow meter in the first gas venting flow path. Then, set the pressure of the first back pressure valve and the second back pressure valve to be the same as the carrier gas inlet pressure, such as 150kPa. Further, adjust the switching valve to connect with the corresponding (equipment or pipeline or sampling cylinder) gas sampling port, and adjust the switching valve to connect the sampling valve with the first flow pressure reducing valve. At this time, open the root valve of the (equipment or pipeline or sampling cylinder) equipment in turn, adjust the first flow regulating valve, make the flow meter display at 50ml / min, and replace quickly for 1-2min. After the replacement is completed, rotate the second three-way valve so that the sample enters the quantitative ring on the gas sampling quantitative valve (i.e., the six-way injection valve), vents through the second back pressure valve, and replaces the sample in the pipeline and the quantitative ring for 0.5-1min. Rotate the gas injection quantitative valve to the injection position, and the carrier gas brings the sample into the chromatogram for chromatographic analysis.

[0090] After the gas sampling quantitative valve completes the injection, it rotates back to the sampling position and switches the switching valve to allow the purge inert gas to enter the flow path to purge the flow path in preparation for the next injection.

[0091] Embodiment 2

[0092] The disclosed embodiment provides a process for volatile sample injection (second branch). Taking liquefied petroleum gas (LPG) analysis as an example, the main components of LPG are propane and butane, and also contain partially dissolved methane, ethane, carbon 5, carbon 6, and a very small amount of carbon 7 and carbon 8 components. The boiling points of the component compounds range from -164°C (methane) to 125°C (n-octane). The specific operation steps are as follows:

[0093] First, according to the highest boiling point of the sample to be tested, set the temperature of the heating zone to ensure that the volatile liquid is vaporized in the flash evaporator and maintains a gas state. Set the temperature of the heating zone to 120°C, and wait for the temperature of the heating zone to be stable. First, adjust the first three-way valve so that its inlet end is connected to the flash tank and the outlet end is connected to the second three-way valve; further, adjust the second three-way valve so that its inlet end is connected to the first three-way valve and the outlet end is connected to the flowmeter in the first gas venting flow path. Further, adjust the switching valve to connect with the corresponding (equipment or pipeline or sampling cylinder) volatile sample sampling port, and adjust the switching valve to connect the sampling valve with the second flow pressure reducing valve. Set the pressure of the first back pressure valve and the second back pressure valve to 150kpa. Open the sampling valve (equipment or pipeline or sampling cylinder) in turn, adjust the second flow pressure reducing valve, set the output pressure slightly higher than the pressure of the first back pressure valve and the second back pressure valve, for example, 180kPa, and further adjust the flowmeter so that the venting flow is 50ml / min, and replace quickly for 4-5min. After the replacement is completed, rotate the second three-way valve to allow the sample to enter the quantitative ring on the gas sampling quantitative valve (i.e., six-way injection valve), vent through the second back pressure valve, and replace the sample in the pipeline and quantitative ring for 0.5-1min. Rotate the gas sampling quantitative valve to the injection position, and the carrier gas will bring the sample into the chromatogram for chromatographic analysis. After the gas sampling quantitative valve completes the injection, turn it back to the sampling position, switch the switching valve, allow the purge inert gas to enter the flow path, purge the flow path, and prepare for the next injection.

[0094] Embodiment 3

[0095] The present disclosure provides a process for liquid medium injection (third branch), taking methanol analysis as an example, the specific operation steps are as follows:

[0096] Adjust the switching valve to connect with the corresponding (equipment or pipeline or sampling cylinder) liquid medium sampling port, and adjust the switching valve to make the sampling valve and the flow control valve connected; further, open the (equipment or pipeline or sampling cylinder) sampling valve and flow control valve in sequence, replace the pipeline and the micro liquid injection valve, and the replacement volume is about 20 times the volume of the entire flow path. After the replacement is completed, rotate the micro injection valve, and the sample enters the chromatogram for analysis.

[0097] The basic principles of the present disclosure are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present disclosure are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present disclosure. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, and are not limitations. The above details do not limit the present disclosure to the necessity of adopting the above specific details to be implemented.

[0098] The block diagrams of the devices, apparatuses, equipment, and systems involved in the present disclosure are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The word "such as" used here refers to the phrase "such as but not limited to", and can be used interchangeably with it.

[0099] Additionally, as used herein, "or" used in a list of items beginning with "at least one" indicates a separate list, so that, for example, a list of "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not mean that the example described is preferred or better than other examples.

[0100] It should also be noted that in the system and method of the present disclosure, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present disclosure.

[0101] Various changes, substitutions, and modifications of the techniques described herein may be made without departing from the teachings defined by the appended claims. Furthermore, the scope of the claims of the present disclosure is not limited to the specific aspects of the processes, machines, manufactures, compositions of events, means, methods, and actions described above. Currently existing or later to be developed processes, machines, manufactures, compositions of events, means, methods, or actions that perform substantially the same functions or achieve substantially the same results as the corresponding aspects described herein may be utilized. Thus, the appended claims include such processes, machines, manufactures, compositions of events, means, methods, or actions within their scope.

[0102] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0103] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present disclosure to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A chromatographic detection method, It is characterized in that The following steps are involved: (1) Injection: Samples at different detection points are introduced into an injection section having a switching valve through a plurality of injection channels, and the injection of each sample is switched by the switching valve; (2) Allocation: Allocation of the sample to different detection branches by switching valves according to the type of the sample from the sample injection section; (3) Pretreatment: performing different pretreatments on the sample in different detection branches; (4) Detection: Detecting the sample after the pretreatment.

2. The chromatographic detection method according to claim 1, It is characterized in that The types of the samples include: gas medium, volatile medium, and liquid medium.

3. The chromatographic detection method according to claim 2, It is characterized in that When the type of the sample is a gas medium, the sample is introduced into a first detection branch having a pressure reducing valve, and the pretreatment includes performing a pressure reducing treatment on the sample.

4. The chromatographic detection method according to claim 2, It is characterized in that When the type of the sample is a volatile medium, the sample is introduced into a second detection branch having a pressure reducing valve and a flash tank, and the pretreatment includes performing a pressure reducing treatment on the sample and performing a flash evaporation treatment on the sample.

5. The chromatographic detection method according to claim 2, It is characterized in that When the sample is a liquid medium, the sample is introduced into a third detection branch having a flow regulating valve and a micro-liquid injection valve, and the pretreatment includes flow regulating treatment and micro-injection treatment of the sample.

6. The chromatographic detection method according to claim 3, It is characterized in that When the type of the sample is a gas medium, after the sample is subjected to a decompression treatment, the pretreatment further includes performing sample replacement on the sample using a first venting branch.

7. The chromatographic detection method according to claim 4, It is characterized in that When the type of the sample is a volatile medium, after the sample is subjected to a decompression treatment and a flash evaporation treatment, the pretreatment further includes performing sample replacement on the sample using a first venting branch.

8. The chromatographic detection method according to claim 2, It is characterized in that When the type of the sample is a gas medium or a volatile medium, after the sample is introduced into the second detection branch having a gas sampling quantitative valve, the pressure in the gas sampling quantitative valve is adjusted by using the second venting branch.

9. The chromatographic detection method according to claim 5, It is characterized in that When the type of the sample is a liquid medium, after the sample is introduced into the third detection branch, the third venting branch is used to discharge the excess sample in the micro-liquid injection valve.

10. The chromatographic detection method according to any one of claims 1 to 9, It is characterized in that Also includes: (5) Inert gas purging: Before or after injection, the multiple injection channels are purged with an inert gas.

11. The chromatographic detection method according to any one of claims 1 to 9, It is characterized in that Also includes: (6) Filtration: Before or after injection, the sample is filtered through a filter.

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