Carbon hydrocarbon compound detection system

Abstract

The invention discloses a carbon hydrocarbon compound detection system which comprises a sample injection assembly, a damping assembly, a switching assembly, a first quantitative tube, a second quantitative tube, a first chromatographic column, a second chromatographic column and a detector, an inlet of the sample introduction assembly is used for receiving a to-be-detected sample, and an outlet is communicated with a first end of the first quantitative tube; wherein the sample introduction assembly can introduce a fluid used for providing flowing power for a to-be-detected sample; the damping assembly is communicated between the second end of the first quantitative tube and the first end of the second quantitative tube and is used for providing flow resistance for the to-be-detected sample; the second end of the second quantitative tube is communicated with the inlet of the switching assembly; the inlet end of the first chromatographic column is communicated with the first outlet of the switching assembly; the inlet end of the second chromatographic column is communicated with the second outlet of the switching assembly, and the outlet end of the second chromatographic column and the outlet end of the first chromatographic column are communicated with the inlet end of the detector through a loop of the switching assembly; the switching assembly can be switched to the state that the inlet of the switching assembly is communicated with the first outlet and the state that the inlet of the switching assembly is communicated with the second outlet.

Description

Technical Field

[0001] This invention relates to the field of gas chromatography analysis technology, and in particular to a system for detecting carbon hydrocarbon compounds. Background Technology

[0002] Current gas chromatography analysis of total hydrocarbons, CH4, C2H2, C2H4, C2H6 and other carbon hydrocarbon compounds generally uses a dual-channel dual-detector gas chromatograph. This means that the gas chromatograph needs to be equipped with two sets of valve assemblies and detectors, which results in high hardware costs, complex system structure, and the response differences of different detectors can easily lead to deviations in the detection results. Summary of the Invention

[0003] In view of this, the present invention provides a carbon hydrocarbon compound detection system with a simplified system structure, reduced cost, and helps to ensure detection accuracy.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A hydrocarbon compound detection system includes: an injection assembly, a damping assembly, a switching assembly, a first quantitative tube, a second quantitative tube, a first chromatographic column, a second chromatographic column, and a detector;

[0006] The inlet of the injection assembly is used to connect the sample to be tested, and the outlet is connected to the first end of the first quantitative tube; wherein, the injection assembly can introduce fluid to provide flow power for the sample to be tested;

[0007] The damping component is connected between the second end of the first metering tube and the first end of the second metering tube, and is used to provide flow resistance for the sample to be tested;

[0008] The second end of the second quantitative tube is connected to the inlet of the switching component;

[0009] The inlet of the first chromatographic column is connected to the first outlet of the switching assembly;

[0010] The inlet of the second chromatographic column is connected to the second outlet of the switching component. The outlets of the first chromatographic column and the first chromatographic column are both connected to the inlet of the detector through the loop of the switching component. The switching component can be switched to connect its inlet to the first outlet and to connect its inlet to the second outlet.

[0011] Optionally, the injection assembly includes an injection valve.

[0012] Optionally, the injection valve is a six-way injection valve;

[0013] The sixth port of the six-way injection valve is used to connect the sample to be tested, the first port is connected to the first end of the first quantitative tube, the fourth port is connected to the second end of the second quantitative tube, the fifth port is used for sample discharge, the third port is connected to the inlet of the switching component, and the second port is used to introduce carrier gas.

[0014] When the six-way injection valve is switched to the injection state, its sixth port is connected to the first port and its fourth port is connected to the fifth port. When the six-way injection valve is switched to the discharge state, its second port is connected to the first port and its fourth port is connected to the third port.

[0015] Optionally, the switching component includes a switching valve.

[0016] Optionally, the switching valve is a six-way switching valve;

[0017] The sixth port of the six-way switching valve is connected to the outlet of the injection assembly, the first port is connected to the inlet of the first chromatographic column, the second port is connected to the outlet of the first chromatographic column, the fifth port is connected to the inlet of the second chromatographic column, the fourth port is connected to the outlet of the second chromatographic column, and the third port is connected to the inlet of the detector.

[0018] When the six-way switching valve is switched to the first state, its sixth port is connected to the first port, and its second port is connected to the third port; when the six-way switching valve is switched to the second state, its sixth port is connected to the fifth port, and its fourth port is connected to the third port.

[0019] Optionally, the damping component includes a damping tube.

[0020] Optionally, it also includes an adjustment component;

[0021] The adjustment component is located in the damping tube and is used to adjust the flow resistance of the damping tube.

[0022] Optionally, the first chromatographic column comprises an alumina capillary column.

[0023] Optionally, the second chromatographic column comprises a porous polymer column.

[0024] Optionally, the detector includes a hydrogen flame ionization detector.

[0025] As can be seen from the above technical solution, the hydrocarbon compound detection system provided by the present invention has an injection component, a first quantitative tube, a damping component, a second quantitative tube, and a switching component that can be sequentially connected. Furthermore, the inlets of the first and second chromatographic columns can be connected to the two outlets of the switching component, and the outlets can be connected to the inlet of the detector. Through the flow resistance of the damping component and the switching action of the switching component, the sample to be tested in the first and second quantitative tubes enters the corresponding chromatographic columns with a time difference, avoiding overlap of components in different quantitative tubes. This facilitates the detection of different components in the sample. Moreover, the above components can form a detection path of single injection – two quantitative tubes in series – dual-column switching separation – single detector detection, and only one detector is configured. This simplifies the structure and reduces the cost of the hydrocarbon compound detection system, while also helping to ensure detection accuracy. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the principle of the hydrocarbon compound detection system provided in an embodiment of the present invention.

[0028] In this configuration, 10 is the first quantitative tube, 20 is the second quantitative tube, 30 is the first chromatographic column, 40 is the second chromatographic column, 50 is the detector, 60 is the six-way injection valve, 61 is the first port, 62 is the second port, 63 is the third port, 64 is the fourth port, 65 is the fifth port, 66 is the sixth port, 70 is the six-way switching valve, 71 is the first port, 72 is the second port, 73 is the third port, 74 is the fourth port, 75 is the fifth port, 76 is the sixth port, and 80 is the damping tube. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] The hydrocarbon compound detection system provided in this embodiment of the invention, such as Figure 1 As shown, it includes: an injection assembly, a damping assembly, a switching assembly, a first quantitative tube 10, a second quantitative tube 20, a first chromatographic column 30, a second chromatographic column 40, and a detector 50;

[0031] The inlet of the injection component is used to connect the sample to be tested, and the outlet is connected to the first end of the first quantitative tube 10; wherein, the injection component can be introduced with fluid to provide flow power for the sample to be tested;

[0032] The damping assembly is connected between the second end of the first metering tube 10 and the first end of the second metering tube 20, and is used to provide flow resistance for the sample to be tested.

[0033] The second end of the second quantitative tube 20 is connected to the inlet of the switching component;

[0034] The inlet of the first chromatographic column 30 is connected to the first outlet of the switching component;

[0035] The inlet of the second chromatographic column 40 is connected to the second outlet of the switching component, and the outlets of the first chromatographic column 30 and the first chromatographic column 30 are both connected to the inlet of the detector 50 through the loop of the switching component; wherein, the switching component can be switched to connect its inlet to the first outlet and to connect its inlet to the second outlet.

[0036] It should be noted that the inlet of the injection component can be the same as the injection port, and can be connected to the injection pipeline for connecting the sample to be tested; the outlet of the injection component can be the sample outlet. Of course, the injection component also has a flow inlet for introducing a fluid that provides flow momentum to the sample to drive it forward within the hydrocarbon detection system. A damping component (flow-blocking component) is connected between the second end of the first quantitative tube 10 and the first end of the second quantitative tube 20, providing resistance to the flow of the sample to delay its entry into the second quantitative tube 20. The first quantitative tube 10 and the second quantitative tube 20... The volume of both quantitative tubes 20 can be 1 mL; the stationary phase of the first chromatographic column 30 and the stationary phase of the second chromatographic column 40 are different; the first chromatographic column 30 can be used to separate components such as CH4, C2H2, C2H4, and C2H6 in the sample to be tested, and the second chromatographic column 40 can be used to separate total hydrocarbons in the sample to be tested; the outlet ends of the first chromatographic column 30 and the second chromatographic column 40 can both be connected to the inlet end of the detector 50 through the corresponding circuit of the switching component. Of course, the connection of the above components can be made through pipelines, and all connection interfaces must be sealed and leak-free to ensure the formation of a complete flow path;

[0037] The switching assembly has at least an inlet, a first outlet, a second outlet, a first loop, and a second loop. The outlet of the first chromatographic column 30 can be connected to the inlet of the detector 50 through the first loop of the switching assembly, and the outlet of the second chromatographic column 40 can be connected to the inlet of the detector 50 through the second loop of the switching assembly. The switching assembly can switch its inlet to connect with the first outlet or to connect with the second outlet. When the switching assembly is switched to connect its inlet with the first outlet (which can be the first state), the sample to be tested in the second quantitative tube 20 first enters the first chromatographic column 30 through the first flow path of the switching assembly (i.e., the flow path between the inlet and the first outlet) due to the fluid action. During this process, due to the flow resistance of the damping assembly, the sample to be tested in the first quantitative tube 10 enters the second quantitative tube 20 with a delay, and will not flow into the first chromatographic column 30 synchronously with the sample to be tested in the second quantitative tube 20; that is, there is a time difference in the feeding of the sample to be tested in the first quantitative tube 10 and the second quantitative tube 20. After the sample to be tested in the second quantitative tube 20 enters the first chromatographic column 30, the switching assembly can switch... When the inlet is switched to be connected to the second outlet (which can be the second state), the sample to be tested in the first quantitative tube 10 passes through the second quantitative tube 20 under the action of the fluid, and enters the second chromatographic column 40 through the second flow path of the switching component (i.e., the flow path between the inlet and the second outlet) for related operations. The components of the sample to be tested exiting the second chromatographic column 40 can be sent to the detector 50 for detection through the second loop of the switching component. Then, the switching component is switched to be connected to the first outlet. In this way, the sample to be tested in the first chromatographic column 30 continues to complete the relevant separation under the action of the fluid. The components separated from the sample to be tested exiting the first chromatographic column 30 can be sent to the detector 50 for detection through the first loop of the switching component. Thus, multiple components can be detected with a single injection of the sample to be tested. Moreover, this hydrocarbon compound detection system uses only one detection path and is equipped with only one detector. This simplifies the structure of the hydrocarbon compound detection system, helps to reduce hardware costs, and avoids the problem of deviation in detection results caused by the response differences of different detectors, thus ensuring detection accuracy.

[0038] In addition, the sample introduction and detection process of this hydrocarbon compound detection system can be as follows:

[0039] Sample injection stage: The sample to be tested can enter the injection component through the inlet of the injection component, and continue to flow under the action of fluid and flow into the first quantitative tube 10 and the second quantitative tube 20 in sequence, thus filling the first quantitative tube 10 and the second quantitative tube 20 in sequence, completing the sample injection preparation.

[0040] Separation and Detection Stage: When the switching component is switched to the first state, the sample to be tested in the second quantitative tube 20 will flow into the first chromatographic column 30 through the first flow path of the switching component under the action of the fluid. During this process, the sample to be tested in the first quantitative tube 10 will not flow into the first chromatographic column 30 simultaneously due to the flow resistance of the damping component. Of course, at this time, the sample to be tested remains in the first chromatographic column 30. Then, the switching component is switched to the second state, and the sample to be tested in the first quantitative tube 10 will flow into the second chromatographic column 40 through the second flow path of the switching component under the action of the fluid, and related separation operations can be performed. The separated target components can be sent to the detector for detection through the second loop of the switching component. After that, the switching component is switched back to the first state, and the sample to be tested in the first chromatographic column 30 will continue to complete the separation of target components under the action of the fluid. The separated target components can be sent to the detector for detection through the first loop of the switching component. Of course, the detector responds to each component and records the chromatographic signal. Finally, the signal is processed by the chromatography workstation to obtain the detection results of each target component, thereby realizing the detection of multiple target components with a single feed.

[0041] In other words, the hydrocarbon compound detection system provided by this solution has its injection component, first quantitative tube 10, damping component, second quantitative tube 20, and switching component connected in sequence. The inlet ends of the first chromatographic column 30 and the second chromatographic column 40 can be connected to the two outlets of the switching component, and the outlet ends can be connected to the inlet end of the detector 50 through the corresponding loop of the switching component. Through the flow resistance of the damping component and the switching function of the switching component, the sample to be tested in the first quantitative tube 10 and the second quantitative tube 20 enters the corresponding chromatographic column with a time difference, avoiding the overlap of components in different quantitative tubes, thus facilitating the detection of different components in the sample to be tested. Moreover, through the above components, a detection path (detection flow path) can be formed, which is single injection - two quantitative tubes in series - dual column switching separation - single detector detection. Only one detector is configured, which simplifies the structure of this hydrocarbon compound detection system, reduces costs, and helps to ensure detection accuracy.

[0042] In short, this solution provides a gas chromatography system that simplifies hardware configuration while ensuring detection accuracy. Moreover, this gas chromatography system can achieve "one-time operation, multi-component detection" through optimized flow path design. In other words, this hydrocarbon compound detection system can be a gas chromatography detection system based on single injection and dual quantitative tubes in series, and can be used for the detection of multi-component samples such as total hydrocarbons and non-methane total hydrocarbons.

[0043] Of course, the design of this hydrocarbon compound detection system has the following beneficial effects:

[0044] 1. Simplified hardware configuration: Only one injection component, two serially connected quantitative tubes, one switching component, and one detector are used to form a single detection channel; compared with the traditional dual-channel dual-detector scheme, it can help simplify the system structure, reduce instrument cost and size, and reduce the maintenance requirements of multiple components;

[0045] 2. Improved detection accuracy: Using the same detector to respond to multiple components avoids systematic errors caused by differences in the responses of dual detectors, and significantly improves the repeatability and accuracy of detection results.

[0046] In this scheme, the sample injection assembly includes an injection valve. The injection valve can be a six-way injection valve or a multi-way injection valve, such as a ten-way injection valve. Of course, these injection valves have the function of introducing carrier gas to provide flow power for the sample to be tested, and also facilitate the switching between the injection state and the effluent state, thereby facilitating the injection and effluent of the sample to be tested within the injection assembly, and providing flow power for the sample to be tested.

[0047] Specifically, such as Figure 1 As shown, the injection valve is a six-way injection valve 60;

[0048] The sixth port of the six-way injection valve 60 is used to connect the sample to be tested, the first port is connected to the first end of the first quantitative tube 10, the fourth port is connected to the second end of the second quantitative tube 20, the fifth port is used for sample discharge, the third port is connected to the inlet of the switching component, and the second port is used to introduce carrier gas.

[0049] When the six-way injection valve 60 is switched to the injection state, its sixth port is connected to the first port and its fourth port is connected to the fifth port. When the six-way injection valve 60 is switched to the discharge state, its second port is connected to the first port and its fourth port is connected to the third port.

[0050] It should be noted that the six-way injection valve 60 can be a high-pressure six-way injection valve specifically for gas chromatography, such as... Figure 1As shown, the six ports of the six-way injection valve 60 can be designated as port 61, port 62, port 63, port 64, port 65, and port 66. Port 66 can be the injection port and can be connected to the injection pipeline. Port 62 can be the carrier gas inlet and is used to introduce carrier gas to provide flow momentum for the sample. Specifically, during sample injection, the six-way injection valve 60 can be switched off first. When switched to the sample injection state, the sixth port 66 of the six-way injection valve 60 is connected to the first port 61, and the fourth port 64 is connected to the fifth port 65. This means the sample to be tested flows into the six-way injection valve 60 from the sixth port 66, then flows out of the six-way injection valve 60 through the first port 61, and sequentially flows into the first quantitative tube 10, the damping assembly, and the second quantitative tube 20. It then flows back into the six-way injection valve 60 from the fourth port 64 and flows out through the fifth port 65. In this way, the sample to be tested... The first quantitative tube 10 and the second quantitative tube 20 are filled sequentially to complete the feeding preparation. Then, the six-way injection valve 60 is switched to the sample dispensing state. At this time, the second port 62 of the six-way injection valve 60 is connected to the first port 61, and the fourth port 64 is connected to the third port 63. That is, the carrier gas flows into the six-way injection valve 60 from the second port 62, then flows out of the six-way injection valve 60 through the first port 61 and flows sequentially into the first quantitative tube 10, the damping component, and the second quantitative tube 20. Then it flows into the six-way injection valve 60 from the fourth port 64. Finally, it is ready to flow out of the six-way injection valve 60 from the third port 66 to prepare for sample dispensing. The carrier gas can promote the forward flow of the sample in the two quantitative tubes. Of course, the six-way injection valve 60 is selected as the injection component in this scheme, which not only facilitates the switching between the injection and dispensing states, but also facilitates the introduction of fluid to provide flow power for the sample. In other words, this scheme provides a carbon hydrocarbon compound detection system based on a single six-way injection valve and dual quantitative tubes.

[0051] Furthermore, the switching assembly includes a switching valve. This switching valve may have two flow paths and two loops, allowing for switching between the two flow paths. The inlet of the first chromatographic column 30 can be connected to the first flow path, and the outlet can be connected to the first loop. Similarly, the second chromatographic column 40 can be connected to the second flow path, and the outlet can be connected to the second loop, thus enabling the switching separation of the first and second chromatographic columns 30. Of course, this design uses a switching valve as the switching assembly to facilitate switching between the different flow paths.

[0052] To go a step further, such as Figure 1 As shown, the switching valve is a six-way switching valve 70;

[0053] The sixth port of the six-way switching valve 70 is connected to the outlet of the injection assembly, the first port is connected to the inlet of the first chromatographic column 30, the second port is connected to the outlet of the first chromatographic column 30, the fifth port is connected to the inlet of the second chromatographic column 40, the fourth port is connected to the outlet of the second chromatographic column 40, and the third port is connected to the inlet of the detector 50.

[0054] When the six-way switching valve 70 is switched to the first state, its sixth port is connected to the first port and its second port is connected to the third port; when the six-way switching valve 70 is switched to the second state, its sixth port is connected to the fifth port and its fourth port is connected to the third port.

[0055] It should be noted that, as Figure 1As shown, the six ports of the six-way switching valve 70 can be designated as port 71, port 72, port 73, port 74, port 75, and port 76. Port 76 can be the injection port and is connected to port 63 of the six-way injection valve 60. A first chromatographic column 30 is connected between ports 71 and 72 of the six-way switching valve 70. A second chromatographic column 40 is connected between ports 75 and 74 of the six-way switching valve 70. Port 73 can be the outlet port and is connected to detector 5. The inlet of 0 is connected; specifically, when the six-way switching valve 70 is switched to the first state, its sixth port 76 is connected to the first port 71 (the two ports form the first flow path), and the second port 72 is connected to the third port 73 (the two ports form the first loop). At this time, the sample to be tested in the second quantitative tube 20 will flow out of the six-way injection valve 60 due to the action of the carrier gas, and flow into the six-way switching valve 70 through the sixth port 76, and then flow out of the six-way switching valve 70 from the first port 71 and into the first chromatographic column 30; of course, due to the flow resistance of the damping component, the first quantitative tube 10 The sample to be tested will not flow into the first chromatographic column 30 simultaneously; when the six-way switching valve 70 is switched to the second state, its sixth port 76 is connected to the fifth port 75 (the two ports form a second flow path), and its fourth port 74 is connected to the third port 73 (the two ports form a second loop). At this time, the sample to be tested in the first quantitative tube 10 will flow out of the six-way injection valve 60 due to the action of the carrier gas, and flow into the six-way switching valve 70 through the sixth port 76, and then flow out of the six-way switching valve 70 from the fifth port 75 and into the second chromatographic column 40; of course, the sample to be tested in the second chromatographic column 40... The target component separated in column 0 can flow into the six-way switching valve 70 through the fourth port 74 and into the detector 50 through the third port 73; similarly, the target component separated from the sample in the first chromatographic column 30 can flow into the six-way switching valve 70 through the second port 72 and into the detector 50 through the third port 73; that is to say, this scheme uses the six-way switching valve 70 as the switching component, which not only facilitates the switching of the two flow paths, but also facilitates the connection of the two chromatographic columns to the two ports of the corresponding flow paths, thereby facilitating the switching and separation of the two chromatographic columns.

[0056] In this plan, such as Figure 1As shown, the damping assembly includes a damping tube 80. That is, the damping tube 80 is connected in series between the first quantitative tube 10 and the second quantitative tube 20. This facilitates flow resistance to the sample flowing into the second quantitative tube 20, delaying the sample's flow into the second quantitative tube 20, thus providing a time difference for sample introduction into the first quantitative tube 10 and the second quantitative tube 20. The damping tube 80 can be a stainless steel damping tube with a length of 0.4m to achieve flow resistance of approximately 30 seconds, and an inner diameter of 0.3mm.

[0057] Specifically, the hydrocarbon compound detection system provided in this embodiment of the invention further includes an adjustment component, which is disposed in the damping tube 80 and used to adjust the flow resistance of the damping tube 80. The adjustment component can be a needle valve and is disposed in the middle part of the damping tube 80. That is, the needle valve can be a section of the middle part of the damping tube 80, so that the flow resistance of the damping tube 80 can be adjusted by the needle valve. In this way, if the sample emission (injection) time difference (time interval) of the first quantitative tube 10 and the second quantitative tube 20 is insufficient, the flow resistance inside the damping tube 80 can be adjusted by the needle valve to make the sample emission time difference of the first quantitative tube 10 and the second quantitative tube 20 adjustable, thereby ultimately ensuring that the sample injection time difference of the two quantitative tubes is stable at 0.5-1.0 minutes, avoiding the overlap of components from different quantitative tubes.

[0058] Furthermore, the first chromatographic column 30 includes an alumina capillary column. The alumina capillary column can be used to separate components such as CH4, C2H2, C2H4, and C2H6 in the sample to be tested.

[0059] Furthermore, the second chromatographic column 40 includes a porous polymer column. This porous polymer column can be used to separate total hydrocarbons from the sample to be analyzed.

[0060] Specifically, detector 50 includes a hydrogen flame ionization detector.

[0061] Of course, this solution provides a sample introduction method, and through a specific analysis system, it can achieve the analysis of total hydrocarbons, CH4, C2H2, C2H4, C2H6 and other multi-component carbon hydrocarbon compounds in the raw materials of the air separation unit, liquid oxygen and ambient air in a single sample introduction.

[0062] In addition, the sample introduction and detection process of this hydrocarbon compound detection system is as follows:

[0063] Sample introduction stage: The sample to be tested enters the flow path through the six-way injection valve and fills the first and second quantitative tubes in sequence;

[0064] Separation and Detection Stage: The six-way injection valve is switched to the injection state. After the sample from the second quantitative tube enters the first chromatographic column, the six-way valve is switched again, allowing the sample from the first quantitative tube to enter the second chromatographic column. After the sample from the second quantitative tube flows into the first chromatographic column, the six-way valve is switched to the second state. Due to the flow resistance of the damping tube, the sample from the first quantitative tube can flow into the second chromatographic column, achieving the injection time difference between the second and first quantitative tubes (the time difference can be adjusted by the needle valve and material of the damping tube, with the core being a 0.4m length ensuring basic flow resistance). The two chromatographic columns separate different target components in the sample (such as total hydrocarbons, CH4, C2H2, C2H4, and C2H6). The separated components sequentially enter the same detector, which responds to each component and records the chromatographic signal. Finally, the signal is processed by the chromatography workstation to obtain the detection results for each target component.

[0065] Furthermore, this solution can achieve the detection of multi-component carbon hydrocarbon compounds through a step-by-step implementation process of "hardware assembly - flow path debugging - parameter calibration - sample detection" combined with specific application scenarios. The following is a detailed description of the implementation method, taking the detection of total hydrocarbons, CH4, C2H2, C2H4, and C2H6 in the feed gas of an air separation unit as an example:

[0066] 1. Hardware selection and assembly

[0067] Core component selection: A high-pressure six-way injection valve and a six-way switching valve specifically for gas chromatography are selected, matched with two chromatographic columns with different stationary phases (the first chromatographic column is an alumina capillary column for separating CH4, C2H2, C2H4, C2H6, etc.; the second chromatographic column is a porous polymer column for separating total hydrocarbons), and two quantitative tubes (each with a volume of 1 mL), a 0.4 m long stainless steel damping tube (0.3 mm inner diameter), and a flame ionization detector (FID) is selected.

[0068] Flow path connection implementation: As required by the technical solution, connect the corresponding port of the six-way injection valve to one end of the first quantitative tube. Connect the other end of the first quantitative tube to one end of the second quantitative tube through a damping tube. Connect the other end of the second quantitative tube to the corresponding port of the six-way injection valve. Connect the outlet (third port) of the six-way injection valve to the inlet (sixth port) of the six-way switching valve. Connect the first chromatographic column between the two points (first port and second port) of the six-way switching valve, and connect the second chromatographic column between the other two points (fifth port and fourth port). The outlets of the two chromatographic columns can be connected to the inlet of the FID detector. Ensure that all connection interfaces are sealed and leak-free to form a complete flow path.

[0069] 2. System debugging and parameter setting

[0070] Flow path airtightness check: Introduce high-purity nitrogen (purity ≥99.999%) into the system, maintain the system pressure at 0.3MPa, hold the pressure for 30 minutes, and confirm that there are no leaks at each interface using the soap film leak detection method to ensure the airtightness of the flow path;

[0071] Injection time difference calibration: Start the six-way injection valve and introduce the standard sample (a mixed gas containing each target component). Observe the sample elution time through the chromatography workstation. If the sample elution interval between the first and second quantitative tubes is insufficient, the damping tube length (±0.05m) or inner diameter can be finely adjusted to ensure that the sample injection time difference between the two quantitative tubes is stable at 0.5-1.0 minutes, thus avoiding the overlap of components in different quantitative tubes.

[0072] Chromatographic and detector parameter settings: Set the column oven temperature program (initial temperature 40℃, hold for 3 minutes, increase to 120℃ at 10℃ / min, hold for 2 minutes); carrier gas (nitrogen) flow rate 30mL / min, hydrogen flow rate 40mL / min, air flow rate 400mL / min; FID detector temperature 200℃. After ensuring that all parameters are stable, put the system into standby mode.

[0073] 3. Standard curve plotting and calibration

[0074] Standard sample preparation: Prepare 5 sets of standard mixed samples with different concentration gradients, covering the expected concentration of the sample to be tested (e.g., total hydrocarbons: 0.1-10 μmol / mol, monomeric hydrocarbons such as CH4 and C2H2: 0.05-5 μmol / mol).

[0075] Standard curve plotting: Inject standard samples sequentially through a six-way injection valve, detect them according to the set parameters, and record the chromatographic peak area of ​​each component; plot the standard curve by linear regression analysis with component concentration as the x-axis and peak area as the y-axis, and calculate the regression equation (R²≥0.995) as the basis for quantitative analysis;

[0076] 4. Actual sample testing and result output

[0077] Sample injection: Collect the raw gas sample from the air separation unit, connect it to the six-way injection valve through the injection pipeline, start the injection program, and the sample will fill the first and second quantitative tubes in sequence to complete the injection preparation;

[0078] Separation and Detection: The six-way injection valve is switched to analytical mode (i.e., feed mode). The sample in the second quantitative tube first enters the first chromatographic column (CH4, C2H2, C2H4, C2H6). Then, the six-way switching valve is switched, and the sample in the second quantitative tube remains in the first chromatographic column. The sample in the first quantitative tube, after being delayed by the damping tube, enters the second chromatographic column, where total hydrocarbons are separated. Then, the sample enters the FID detector, which responds and records the total hydrocarbon signal. Next, the six-way switching valve is switched back to its original position, and the components in the first chromatographic column are separated under the carrier gas (CH4, C2H2, C2H4, C2H6). The separated components sequentially enter the FID detector, which responds and records the chromatographic signal. The final peak order is: total hydrocarbons, CH4, C2H2, C2H4, C2H6, etc.

[0079] Results calculation: The chromatography workstation calls the preset standard curve, performs quantitative calculation on the peak area of ​​each component, and automatically outputs the concentration values ​​of total hydrocarbons, CH4, C2H2, C2H4, and C2H6, completing the simultaneous detection of multiple components in one injection;

[0080] Through the above specific implementation steps, efficient and accurate detection of multi-component carbon hydrocarbon compounds in samples such as raw materials, liquid oxygen, and ambient air of the air separation unit can be achieved, fully realizing the core objectives of this solution: "simplified structure, convenient operation, and accurate detection".

[0081] Of course, this hydrocarbon compound detection system has the following characteristics compared to existing gas chromatography detection systems:

[0082] 1. Simplified device structure: Existing traditional dual-valve dual-detector chromatographic analysis devices have complex structures. This solution adopts a one-valve-one-detector configuration, which can reduce hardware components, make the device more compact, reduce the size and cost of the instrument, and also facilitate the maintenance and upkeep of the instrument.

[0083] 2. Improve detection accuracy: Different detectors may have different responses, which can affect the accuracy of the detection results. This solution uses a single detector for detection in a one-valve-one-detector system, avoiding the result deviation caused by the difference in response of two detectors, thereby improving the accuracy and reliability of the detection results.

[0084] 3. Improved ease of operation: Existing dual-valve dual-detector systems typically require two injections to separately determine monomeric hydrocarbons and non-methane total hydrocarbons, which is cumbersome. This solution's single-valve single-detector system, through the switching of the injection valve and a reasonable flow path design, can complete the detection of total hydrocarbons and methane with a single injection, greatly simplifying the operation process and saving time and labor costs.

[0085] In other words, the hydrocarbon compound detection system using this scheme can achieve the following expected results:

[0086] 1. Simplified hardware configuration: Only one six-way injection valve, one six-way switching valve and one detector are used to form a single detection channel; compared with the traditional dual-channel dual-detector solution, the number of core control systems and detectors is reduced by 50%, reducing instrument cost and size, while reducing the maintenance requirements of multiple components;

[0087] 2. Improved detection accuracy: Using the same detector to respond to multiple components avoids systematic errors caused by differences in the responses of dual detectors, and significantly improves the repeatability and accuracy of detection results.

[0088] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0089] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A system for detecting carbon hydrocarbon compounds, characterized in that, include: The sample injection assembly, damping assembly, switching assembly, first quantitative tube (10), second quantitative tube (20), first chromatographic column (30), second chromatographic column (40) and detector (50); The inlet of the injection component is used to receive the sample to be tested, and the outlet is connected to the first end of the first quantitative tube (10); wherein, the injection component can be supplied with fluid to provide flow power for the sample to be tested; The damping component is connected between the second end of the first quantitative tube (10) and the first end of the second quantitative tube (20), and is used to provide flow resistance for the sample to be tested; The second end of the second quantitative tube (20) is connected to the inlet of the switching component; The inlet of the first chromatographic column (30) is connected to the first outlet of the switching component; The inlet of the second chromatographic column (40) is connected to the second outlet of the switching component, and the outlet of the first chromatographic column (30) and the outlet of the first chromatographic column (30) are both connected to the inlet of the detector (50) through the loop of the switching component; wherein, the switching component can switch its inlet to be connected to the first outlet or to be connected to the second outlet.

2. The hydrocarbon compound detection system according to claim 1, characterized in that, The injection assembly includes an injection valve.

3. The hydrocarbon compound detection system according to claim 2, characterized in that, The injection valve is a six-way injection valve (60). The sixth port of the six-way injection valve (60) is used to connect the sample to be tested, the first port is connected to the first end of the first quantitative tube (10), the fourth port is connected to the second end of the second quantitative tube (20), the fifth port is used to discharge the sample, the third port is connected to the inlet of the switching component, and the second port is used to introduce carrier gas. When the six-way injection valve (60) is switched to the injection state, its sixth port is connected to the first port and its fourth port is connected to the fifth port. When the six-way injection valve (60) is switched to the discharge state, its second port is connected to the first port and its fourth port is connected to the third port.

4. The hydrocarbon compound detection system according to claim 1, characterized in that, The switching component includes a switching valve.

5. The hydrocarbon compound detection system according to claim 4, characterized in that, The switching valve is a six-way switching valve (70); The sixth port of the six-way switching valve (70) is connected to the outlet of the injection component, the first port is connected to the inlet of the first chromatographic column (30), the second port is connected to the outlet of the first chromatographic column (30), the fifth port is connected to the inlet of the second chromatographic column (40), the fourth port is connected to the outlet of the second chromatographic column (40), and the third port is connected to the inlet of the detector (50). When the six-way switching valve (70) is switched to the first state, its sixth port is connected to the first port and its second port is connected to the third port; when the six-way switching valve (70) is switched to the second state, its sixth port is connected to the fifth port and its fourth port is connected to the third port.

6. The hydrocarbon compound detection system according to claim 1, characterized in that, The damping assembly includes a damping tube (80).

7. The hydrocarbon compound detection system according to claim 6, characterized in that, It also includes adjustment components; The adjustment component is disposed on the damping tube (80) and is used to adjust the flow resistance of the damping tube (80).

8. The hydrocarbon compound detection system according to claim 1, characterized in that, The first chromatographic column (30) comprises an alumina capillary column.

9. The hydrocarbon compound detection system according to claim 1, characterized in that, The second chromatographic column (40) comprises a porous polymer column.

10. The hydrocarbon compound detection system according to claim 1, characterized in that, The detector (50) includes a hydrogen flame ionization detector.

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