A split injection system for a gas chromatograph and its working method

Abstract

The present invention relates to a split injection system for a gas chromatograph and its working method. The system includes an injector and a control component. The injector includes an injection outer shell, a support frame, a clamp, a temperature sensor, a heating tube, a liner tube, and a sample filling tube, which are sequentially arranged from outside to inside. A heat preservation and isolation structure is provided between the support frame and the injection outer shell. The temperature sensor and the heating tube are respectively connected to the control component. A first through groove is provided in the liner tube. By setting the injector and the control component, the injector includes an injection outer shell, a support frame, a clamp, a temperature sensor, a heating tube, a liner tube, and a sample filling tube, which are sequentially arranged from outside to inside. And a heat preservation and isolation structure is provided between the support frame and the injection outer shell. The liner tube is fully sealed, and the components will not contaminate the heating tube, realizing automatic temperature control. By setting the heat preservation and insulation structure, the degree of temperature attenuation is reduced.

Description

Technical Field

[0001] The present invention relates to a gas chromatograph, and more specifically to a split injection system of a gas chromatograph and its working method. Background Art

[0002] In gas chromatograph analysis, due to differences in sample properties, sample content, sample composition, sample state, analysis purposes, and analysis requirements, different requirements are imposed on the injection system. Common injection systems include split injection systems, splitless injection systems, programmed temperature vaporization injection systems, etc., which greatly improve the quantitative accuracy of different sample analyses. Split injection is to first inject a larger volume of sample into the vaporization chamber of a gas capillary column chromatograph. After the sample is vaporized by programmed temperature, it is uniformly mixed with the carrier gas. Through a splitter, the sample is proportionally split into two parts with a large difference in flow rates. The part with a smaller flow rate enters the capillary column, and the part with a larger flow rate is emptied and discharged.

[0003] However, the heating and splitting part of the current injection system is separated and exposed, without a temperature sensor, belonging to semi-automatic or open-loop temperature control, and unable to achieve full-automatic temperature control. In addition, the injection system is not provided with a heat insulation device, and it is not convenient to clean the liner. The injector is far from the GC chromatograph, and the temperature decay is very fast.

[0004] Therefore, it is necessary to design a new system to achieve full-automatic temperature control, set up a heat insulation structure, and reduce the degree of temperature decay. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a split injection system of a gas chromatograph and its working method.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions: A split injection system of a gas chromatograph includes an injector and a control component. The injector includes an injection outer shell, a support frame, a clamp, a temperature sensor, a heating tube, a liner, and a sample filling tube sequentially arranged from outside to inside. A heat insulation structure is provided between the support frame and the injection outer shell. The temperature sensor and the heating tube are respectively connected to the control component. A first through groove is provided in the liner.

[0007] Its further technical solution is: The heat insulation structure includes asbestos.

[0008] Its further technical solution is as follows: An upper sample injection component is further connected to the sample injection outer shell. The upper sample injection component includes a carrier gas pipe, a carrier gas valve, and a carrier gas screw. A carrier gas through groove is provided in the carrier gas screw. A second through groove is provided in the carrier gas pipe. The second through groove is communicated with the carrier gas through groove. The carrier gas valve is connected to the carrier gas pipe, and the carrier gas valve is connected to the control component. The carrier gas pipe is connected to the sample injection outer shell, and the first through groove is communicated with the second through groove.

[0009] Its further technical solution is as follows: A sample injection part is further connected to the upper end of the carrier gas screw. A sample injection port is provided in the sample injection part. A sample injection isolation pad is provided between the sample injection part and the carrier gas screw.

[0010] Its further technical solution is as follows: A sample injection sealing top cover is connected to the outer end of the sample injection part. A snap ring is provided at the upper end of the sample injection sealing top cover. The upper end of the sample injection part extends upward above the sample injection sealing top cover, and the snap ring is connected to the upper end of the sample injection part.

[0011] Its further technical solution is as follows: A conical through groove is further provided in the liner tube. The conical through groove is located below the first through groove, and the first through groove is communicated with the conical through groove. A lower sample injection component is connected to the lower end of the sample injection outer shell. The lower sample injection component includes a lower sample injection tube, a shunt tube, and a shunt valve. A lower sample injection through groove is provided in the lower sample injection tube. A third through groove is provided in the shunt tube. The lower sample injection through groove is communicated with the conical through groove and the third through groove respectively. The shunt valve is connected to the shunt tube.

[0012] Its further technical solution is as follows: A sample injection needle is further connected to the lower part of the lower sample injection tube. A fourth through groove is provided in the sample injection needle. The fourth through groove is communicated with the lower sample injection through groove.

[0013] Its further technical solution is as follows: A sealing lower cover is connected to the outside of the lower sample injection tube. The sealing lower cover is connected to the lower end of the sample injection outer shell. A sample injection needle sealing cover is connected to the outside of the sample injection needle. A sample injection needle support column is connected to the outside of the sample injection needle sealing cover.

[0014] Its further technical solution is as follows: The control component includes a control box, a temperature controller, a circuit board, a power supply, a first solenoid valve switch, and a second solenoid valve switch. The first solenoid valve switch is connected to the carrier gas valve, and the second solenoid valve switch is connected to the shunt valve. The first solenoid valve switch, the second solenoid valve switch, and the temperature controller are respectively connected to the circuit board, and the power supply is connected to the circuit board. The first solenoid valve switch, the second solenoid valve switch, the temperature controller, the circuit board, and the power supply are respectively placed in the control box. The circuit board includes an MCU and a power heating drive circuit. The temperature sensor, the power heating drive circuit, the heating tube, and the temperature controller are respectively connected to the MCU.

[0015] The present invention also provides a working method for a split injection system of a gas chromatograph, including:

[0016] The control component controls the heating time and temperature of the heating tube according to the preset temperature control curve PID parameters. The temperature detected by the temperature sensor is transmitted to the control component in real time, and the control component adjusts the heating time and temperature of the heating tube. The control component realizes split injection control by setting the split ratio or non-split and the opening and closing times of the first solenoid valve switch and the second solenoid valve switch through a program.

[0017] The beneficial effects of the present invention compared with the prior art are as follows: By setting an injector and a control component, the injector includes an injection outer shell, a support frame, a temperature sensor, a heating tube, and a liner arranged in sequence from outside to inside. A heat preservation and isolation structure is provided between the support frame and the injection outer shell, and the liner is fully sealed, so that the components will not contaminate the heating tube, realizing fully automatic temperature control. By setting a heat preservation and insulation structure, the degree of temperature attenuation is reduced.

[0018] The following further describes the present invention with reference to the drawings and specific embodiments. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is a three-dimensional structure diagram of the injector provided by a specific embodiment of the present invention;

[0021] Figure 2 It is a three-dimensional structure diagram of the injector provided by a specific embodiment of the present invention (removing the bracket);

[0022] Figure 3Explosion structure schematic diagram of the sampler provided by the specific embodiment of the present invention;

[0023] Figure 4 Sectional structure schematic diagram of the sampler provided by the specific embodiment of the present invention;

[0024] Figure 5 Three-dimensional structure schematic diagram of the control component provided by the specific embodiment of the present invention. Detailed implementation manners

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0028] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0029] In the present invention, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the contact between the first and second features through additional features therebetween rather than direct contact. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0031] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0032] As Figures 1 to 5 shown in the specific embodiment, a split injection system of a gas chromatograph provided in this embodiment can be used in the analysis process of a gas chromatograph, and is applicable to the automatic programmed temperature vaporization at the front end of a gas chromatograph, i.e., a capillary chromatographic column. The thermal desorption and split injection device can realize the controllability of the split / non-split program. Meeting the detection requirements of phthalate in the RoHS2.0 standard, in addition to detecting phthalate, a split injection system of a gas chromatograph can also detect red phosphorus flame retardants, organic solvent residues, polymer materials, volatile organic compounds in materials, etc. The sample analysis time is short, and the sample analysis time of 20 minutes / sample fully meets the rapid screening requirements of enterprise users; direct injection is adopted, and the operation is simple. It can directly inject solid or liquid samples, and the result can be obtained through five-step operation. Even production line workers can operate it.

[0033] A gas chromatography system consists of an adsorbent contained in a liner 63 of an injector, or a stationary phase with a liquid coated on an inert solid, and a mobile phase of a gas continuously passing through the liner 63. After adding the sample to be separated and analyzed from the top of the injector into the liner 63, due to the different adsorption or dissolution abilities of the stationary phase for each component in the sample, that is, the distribution coefficients of each component between the stationary phase and the mobile phase are different. When the components are repeatedly distributed between the two phases many times and move forward with the mobile phase, the moving speeds of each component along the liner 63 are different. The component with a small distribution coefficient is retained by the stationary phase for a short time and can flow out from the end of the chromatographic column more quickly. Plotting the concentration of each component flowing out from the end of the column against the time after injection, the resulting graph is called a chromatogram.

[0034] Please refer to Figures 1 to 4 , the split injection system of a gas chromatograph described above includes an injector and a control component. The injector includes an injection outer shell 50, a support frame 60, a clamp 64, a temperature sensor 62, a heating tube 61, a liner 63, and a sample filling tube 65 arranged in sequence from outside to inside. A thermal insulation structure is provided between the support frame 60 and the injection outer shell 50. The temperature sensor 62 and the heating tube 61 are respectively connected to the control component, and a first through groove is provided in the liner 63.

[0035] In this embodiment, by providing a thermal insulation structure between the injection outer shell 50 and the support frame 60, the objects in the support frame 60 can be thermally insulated, and the temperature decay rate can be slowed down. In addition, a temperature sensor 62 is provided to detect the temperature of the heating tube 61 in real time and feedback it to the control component, and the control component adjusts parameters such as the heating time and temperature of the heating tube 61 in real time, so as to realize the full-automatic control of the temperature of the entire system.

[0036] In addition, the injection outer shell 50 is an aluminum alloy profile cylinder, which plays a role in fixing the top cover 51 and sealing the bottom cover 66, and also plays a role in heat insulation.

[0037] In one embodiment, the above thermal insulation structure includes asbestos, and the space between the injection outer shell 50 and the support frame 60 is filled with asbestos to play a role in heat insulation.

[0038] In one embodiment, please refer to Figures 3 to 4 , a clamp 64 is connected to the outer end of the above temperature sensor 62. The clamp 64 can fix the temperature sensor 62 on the heating tube 61.

[0039] In this embodiment, the temperature sensor 62 is, but not limited to, a K-type thermocouple temperature sensor 62, and the heating tube 61 is, but not limited to, an MCH cermet heating element tube.

[0040] Specifically, the MCH cermet heating element tube can achieve multi-stage temperature control by program control of the control component, and the heating rate, constant temperature time, and number of temperature control segments can all be set. It has a rapid heating rate and fast temperature compensation; when starting with a power of 500W for 20S, the temperature can reach above 600°C; when starting with the rated power for 10S, it can reach above 200°C.

[0041] The K-type thermocouple temperature sensor 62 is a K-type thermocouple with cold junction compensation, which collects the heating temperature of the MCH cermet heating element tube. It has a wide temperature range, can withstand high temperatures of up to thousands of degrees Celsius, has good durability, and does not have self-heating.

[0042] In addition, the temperature sensor 62 and the heating tube 61 are respectively provided with leads, and the leads are led out together from the opening of the top cover 51 of the sampling housing 50. The opening is sealed with high-temperature sealant, and the outside of the leads is provided with high-temperature resistant protective sleeves.

[0043] In this embodiment, a tapered through groove is further provided in the liner 63. The tapered through groove is located below the first through groove and is connected to the first through groove.

[0044] In addition, the material of the liner 63 is quartz glass or stainless steel tube. There is a tapered through groove with a small diameter at the lower end of the liner 63, which serves to support the internal sample filling tube 65 and increase the contact surface with the sample to ensure complete vaporization. The liner 63 is cleaned regularly to prevent contamination, and when cleaning, the liner 63 is taken out from the lower end.

[0045] Preferably, a sample filling tube 65 is further embedded in the liner 63. The sample filling tube 65 is a quartz glass tube with a relatively short length, about 1 / 3 of the liner 63, and is located in the middle of the liner 63 where the temperature is the highest. The sample filling tube 65 is filled with a mixture of samples and inert solids. The samples are generally electronic products containing harmful substances such as lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyls, polybrominated diphenyl ethers, plastics, or foods with pesticide residues.

[0046] In one embodiment, please refer to Figure 3 , the upper end of the above-mentioned sampling housing 50 is provided with a top cover 51. The upper end of the top cover 51 protrudes upward with a first insertion ring, and the outside of the first insertion ring is provided with a thread. The lower end of the sampling housing 50 is provided with a lower cover 52, and the lower cover 52 protrudes downward with a second insertion ring, and the outside of the second insertion ring is provided with a thread.

[0047] In one embodiment, please refer to Figure 4, a sealing upper cover 40 is connected to the outer periphery of the above-mentioned top cover 51. The sealing upper cover 40 is threadedly connected to the top cover 51. In addition, a first circlip 33 is connected between the sealing upper cover 40 and the carrier gas screw 30, and an upper cover metal washer 41 is connected above the first circlip 33. The upper cover metal washer 41 serves to raise the height of the sealing upper cover 40. In addition, an upper cover washer 34 is connected to the outer periphery of the upper end of the liner 63. The upper cover washer 34 includes an upper conical graphite pad and a sealing ring sleeve. The sealing ring sleeve is sleeved on the liner 63 and is close to the upper port of the liner 63. The upper cover washer 34 seals the liner 63 completely, and the components will not contaminate the heating tube 61. A sealing graphite washer 35 is also provided between the top cover 51 and the support frame 60. The sealing graphite washer 35 abuts against the upper end of the heating tube 61. The upper conical graphite pad is made of pure soft graphite, and the sealing ring sleeve is a graphite-containing polyimide composite material such as DuPont Vespel SP-21, which contains 15% graphite and has the advantages of high temperature resistance, excellent elasticity, and high creep resistance impedance.

[0048] In this embodiment, the top cover 51 and the bottom cover 52 are the flanges at both ends of the sampling housing 50.

[0049] In one embodiment, a bottom cover washer is connected to the outer periphery of the lower end of the liner 63. The bottom cover washer includes a conical graphite pad 67 and a lower sealing washer 671. The conical graphite pad 67 is made of pure soft graphite, and the lower sealing washer 671 is a graphite-containing polyimide composite material such as DuPont Vespel SP-21, which contains 15% graphite and has the advantages of high temperature resistance, excellent elasticity, and high creep resistance impedance. The conical graphite pad 67 is sleeved on the liner 63 and is close to the lower port of the liner 63. When the temperature exceeds 400 °C, the upper cover washer 34 and the bottom cover washer are generally made of graphite pads. The bottom cover washer seals the liner 63 completely, and the components will not contaminate the heating tube 61. A sealing graphite washer 69 is also provided between the bottom cover 52 and the support frame 60. The sealing graphite washer 69 abuts against the lower end of the heating tube 61. In addition, a sealing bottom cover 66 is threadedly connected to the bottom cover 52, and a lower metal washer 78 is connected between the sealing bottom cover 66 and the bottom cover. The lower metal washer 78 serves to raise the height of the sealing bottom cover 66.

[0050] Thus, it can be seen that the upper cover washer 34 and the bottom cover washer seal the liner 63 completely, and the components will not contaminate the heating tube 61.

[0051] In one embodiment, please refer to Figures 2 to 4, an upper sample injection component is further connected to the upper surface of the above-mentioned sample injection housing 50. The upper sample injection component includes a carrier gas pipe 31, a carrier gas valve, and a carrier gas screw 30. A carrier gas through groove is provided in the carrier gas screw 30, and a second through groove is provided in the carrier gas pipe 31. The second through groove communicates with the carrier gas through groove. The carrier gas valve is connected to the carrier gas pipe 31 and is connected to the control component. The carrier gas pipe 31 is connected to the sample injection housing 50, and the first through groove communicates with the second through groove.

[0052] The lower end of the carrier gas screw 30 is embedded in the first insertion ring, and a hexagonal nut is installed on the outer side of the carrier gas screw 30. The hexagonal nut is in threaded fit with the first insertion ring to achieve a detachable connection between the carrier gas screw 30 and the sample injection housing 50.

[0053] The carrier gas screw 30 and the carrier gas pipe 31 are welded together by vacuum, and the inner cavities of the carrier gas pipe 31 and the carrier gas screw 30 communicate. The carrier gas pipe 31 is provided with a carrier gas valve joint nut 32, and the carrier gas valve joint nut 32 is used to connect with the carrier gas valve. The carrier gas valve is located in the control box 80. The carrier gas valve includes a pressure stabilizing valve 86, a fine adjustment valve, and an electromagnetic valve switch. The carrier gas is generally helium or hydrogen.

[0054] In one embodiment, please refer to Figures 2 to 4 , the above-mentioned sealing upper cover 40 is arranged on the outer periphery of the carrier gas screw 30, and a first snap ring 33 is connected to the outer periphery of the carrier gas screw 30. The sealing upper cover 40 is used to fix and press the carrier gas screw 30, so that the carrier gas screw 30 and the following conical graphite gasket and sealing ring 68 are tightly pressed together to prevent gas leakage. The first snap ring 33 is to prevent the sealing upper cover 40 from falling off.

[0055] In one embodiment, please refer to Figures 2 to 4 , the upper end of the above-mentioned carrier gas screw 30 is further connected with a sample injection part 21. An injection port is provided in the sample injection part 21, and an injection isolation pad 22 is arranged between the sample injection part 21 and the carrier gas screw 30.

[0056] Preferably, the outer end of the above-mentioned sample injection part 21 is connected with a sample injection sealing top cover 23. A snap ring 20 is arranged at the upper end of the sample injection sealing top cover 23. The upper end of the sample injection part 21 extends upward above the sample injection sealing top cover 23, and the snap ring is connected to the upper end of the sample injection part 21.

[0057] The injection seal top cover 23 is provided with an injection part 21, and a small pinhole and an inverted cone needle tube guide hole are provided in the injection part 21. The inverted cone needle tube guide hole and the small pinhole can be used for manual injection or liquid injection. During manual injection, the injection needle pierces the injection isolation pad 22 below. The outside of the injection part 21 is a retaining spring 20. Before injection, the injection seal top cover 23 is opened, the solid sample is placed in the middle of the quartz tube, and the two ends are fixed with quartz wool. The prepared sample tube is clamped with tweezers or hooked with a hook and placed in the liner 63 of the injector, and then the injection seal top cover 23 is tightened until it is tightened. At this time, the injection part 21 and the injection isolation pad 22 below will not rotate with the injection seal top cover 23, so as to avoid the wear of the injection isolation pad 22.

[0058] Specifically, the above-mentioned sample injection isolation pad 22 is but not limited to a graphite pad, a sealing pad with a high temperature resistant silicone rubber pad with a polytetrafluoroethylene film, or a graphite-containing polyimide composite material such as DuPont Vespel SP-21, which has 15% graphite added and has the advantages of high temperature resistance, excellent elasticity, and high creep resistance. During operation, keep the temperature as low as possible or keep away from heating elements to prevent contamination of the sample to be analyzed.

[0059] In one embodiment, see Figures 2 to 4 The lower end of the above-mentioned injection housing 50 is connected to a lower injection assembly, which includes a lower injection tube 70, a diverter tube 77 and a diverter valve. The lower injection tube 70 is provided with a lower injection groove, and the diverter tube 77 is provided with a third groove. The lower injection groove is connected to the conical groove and the third groove respectively, and the diverter valve is connected to the diverter tube 77. The diverter tube 77 is at the lower end, and the liner 63 is completely sealed, so that the components will not contaminate the heating tube 61, and the temperature control cracking and diverting integrated control can be realized.

[0060] The lower sample injection tube 70 is welded with the diverter tube 77. The diverter tube 77 is provided with a diverter valve joint nut 71. The diverter valve is located in the control box 80. The diverter valve includes a three-way switching valve, a solenoid valve switch, and a needle valve.

[0061] In one embodiment, see Figures 2 to 4 The lower portion of the lower injection tube 70 is also connected to an injection needle 75, and a fourth through groove is provided in the injection needle 75, and the fourth through groove is connected to the lower injection through groove.

[0062] In this example, see Figure 2 , Figure 3 , Figure 4, a sample injection needle gasket 74 is provided at the upper end of the sample injection needle 75. The sample injection needle gasket 74 is a conical sealing gasket that wraps the sample injection needle 75 and is made of the same material as the sealing washer. The shunted gas enters the GC gas chromatograph inlet through the sample injection needle 75. The carrier gas and the sample gas components are shunted into two parts with a large difference in flow rate in proportion. The part with a smaller flow rate enters the capillary column of the gas chromatograph through the sample injection needle 75, and the part with a larger flow rate is discharged from the shunt tube 77. A sample injection sealing gasket 76 is provided at the lower end of the above-mentioned sample injection needle gasket 74. In this embodiment, the sample injection sealing gasket 76 is a washer, and the material of the sample injection sealing gasket 7 is the same as that of the sealing ring gasket.

[0063] In addition, a conical graphite gasket 67 is provided between the lower end of the lower sample injection tube 70 and the lower end of the liner 63. A lower sealing gasket 671 is provided at the lower end of the conical graphite gasket 67. A sealing graphite gasket 69 is provided between the lower end of the heating tube 61 and the lower cover 52 of the sample injection housing 50. The material is pure soft graphite. There is one piece of sealing graphite gasket 69 on each of the upper and lower sides, which is closely attached to the upper and lower ends of the heating tube 61 to prevent air leakage and contamination of the heating tube 61 wall. The conical graphite gasket 67 is closely attached to the liner 63, and try to keep the temperature low or away from the heating element during operation. Generally, graphite gaskets are used when the temperature exceeds 400°C. The lower sealing gasket 671 can be a polytetrafluoroethylene high-temperature resistant silicone rubber gasket, a graphite-containing polyimide resin composite material such as DuPont Vespel SP-21, which contains 15% graphite and has the advantages of high temperature resistance, excellent elasticity, and high creep resistance.

[0064] In one embodiment, please refer to Figures 2 to 4 , the above-mentioned lower sample injection tube 70 is externally connected to the above-mentioned sealed lower cover 66. The sealed lower cover 66 is connected to the lower end of the sample injection housing 50. The outside of the sample injection needle 75 is connected to a sample injection needle sealing cover 72, and the outside of the sample injection needle sealing cover 72 is connected to a sample injection needle support column 73.

[0065] Preferably, a bracket 10 is provided on the outside of the above-mentioned sample injection housing 50 for fixing the bracket 10 such as the metal outer cover to the sample injection housing 50, which plays a role in supporting and protecting the sample injection needle 75.

[0066] In one embodiment, please refer to Figure 5, the above control components include a control box 80, a temperature controller, a circuit board, a power supply, a first solenoid valve switch, and a second solenoid valve switch. The first solenoid valve switch is connected to the carrier gas valve, and the second solenoid valve switch is connected to the split valve. The first solenoid valve switch, the second solenoid valve switch, and the temperature controller are respectively connected to the circuit board, and the power supply is connected to the circuit board. The first solenoid valve switch, the second solenoid valve switch, the temperature controller, the circuit board, and the power supply are respectively placed in the control box 80. In addition, the carrier gas valve and the split valve are also connected to the control box 80. The temperature controller can be used to set the temperature control curve program for temperature rise through a computer, with a temperature control range of 50 - 450°C, and generally applied below 400°C. The pyrolysis program has a temperature rise from 200°C to 450°C, and the micro-pyrolysis time is 2 minutes. The carrier gas valve includes a solenoid valve, a pressure regulator valve 86, and a fine adjustment valve.

[0067] The above circuit board includes an MCU, a power heating drive circuit, a temperature sensor 62, a power heating drive circuit, a carrier gas valve, a heating tube 61, and a temperature controller are respectively connected to the MCU. The power supply is a power switch power supply but not limited to this.

[0068] In addition, several gas path adapters 84, 5PIN aviation connectors 83, a power socket 82, and a USB socket 81 are also provided on the above control box 80.

[0069] Specifically, the above split valve includes a solenoid valve, a three-way valve, and a needle valve 87. A fine adjustment valve 85 is also provided on the control box 80.

[0070] This system sets the split ratio or non-split and valve opening and closing time through a program. Place the chromatographic column pre-pressure regulating valve on the split gas path, which can change the pre-column pressure under the condition of constant total flow. The higher the pre-column pressure, the greater the column flow rate and the faster the analysis speed. To change the split ratio under the condition of constant pre-column pressure, that is, constant column flow rate, then adjust the total flow. The greater the total flow, the greater the split ratio. For example, when the split flow is 100 mL / min and the column internal flow is 1 mL / min, the split ratio is 100:1 at this time.

[0071] The temperature control process of the entire system uses the proportional, integral, and differential PID temperature control algorithm. The program realizes automatic temperature control by presetting the PID parameters of the temperature control curve. The temperature sensor 62 uses a K-type thermocouple, and through the cold junction compensation thermocouple digital converter dedicated IC to the MCU. This IC integrates a local temperature sensor, a precision amplifier, an ADC, and a voltage reference, and can digitize the thermocouple signal. The heating tube 61 is driven by the PWM signal output by the MCU to control the heating power NMOS tube to control the heating time and current magnitude. Typical temperature control process: The temperature of the o-xylene analysis program rises to 50°C and holds for 1 minute, rises to 450°C at a rate of 20°C per minute and holds for 4 minutes, and the GC gas chromatograph workstation automatically draws the peak spectrum. The entire system has a high degree of automation, good analysis spectrum effect, fast speed, simple structure, convenient operation, and high cost performance.

[0072] The above-mentioned split injection system for a gas chromatograph, by setting an injector and a control component, the injector includes an injection outer shell 50, a support frame 60, a clamp 64, a temperature sensor 62, a heating tube 61, a liner 63 and a sample filling tube 65 arranged in sequence from outside to inside, and a heat preservation and isolation structure is provided inside the support frame 60 and the injection outer shell 50. The liner 63 is fully sealed, and the components will not contaminate the heating tube 61, realizing fully automatic temperature control, setting a heat preservation and insulation structure, and reducing the degree of temperature attenuation.

[0073] In one embodiment, a working method of a split injection system for a gas chromatograph is also provided, including:

[0074] The control component controls the heating time and temperature of the heating tube 61 according to the preset temperature control curve PID parameters, and the temperature detected by the temperature sensor 62 is transmitted to the control component in real time, and the control component adjusts the heating time and temperature of the heating tube 61. The control component realizes split injection control by setting the split ratio or non-split and the opening and closing times of the first solenoid valve switch and the second solenoid valve switch through a program.

[0075] It should be noted that those skilled in the art can clearly understand that the specific implementation process of the above-mentioned working method of a split injection system for a gas chromatograph can refer to the corresponding description in the foregoing embodiment of a split injection system for a gas chromatograph. For the convenience and brevity of description, it will not be repeated here.

[0076] The above only uses embodiments to further illustrate the technical content of the present invention, so as to make it easier for readers to understand, but it does not mean that the implementation manners of the present invention are limited to this. Any technical extension or re-creation made according to the present invention is protected by the present invention. The protection scope of the present invention is subject to the claims.

Claims

1. A split injection system for a gas chromatograph, characterized in that, it includes an injector and a control component. The injector includes an injection outer shell, a support frame, a clamp, a temperature sensor, a heating tube, a liner tube, and a sample filling tube arranged in sequence from outside to inside. A heat insulation and isolation structure is provided between the support frame and the injection outer shell. The temperature sensor and the heating tube are respectively connected to the control component. A first through groove is provided in the liner tube; a tapered through groove is also provided in the liner tube. The tapered through groove is located below the first through groove and is communicated with the first through groove. The lower end of the injection outer shell is connected with a lower injection component. The lower injection component includes a lower injection tube, a split tube, and a split valve. A lower injection through groove is provided in the lower injection tube, and a third through groove is provided in the split tube. The lower injection through groove is communicated with the tapered through groove and the third through groove respectively. A split valve is connected to the split tube; an upper injection component is also connected to the upper part of the injection outer shell. The upper injection component includes a carrier gas tube, a carrier gas valve, and a carrier gas screw. A carrier gas through groove is provided in the carrier gas screw, and a second through groove is provided in the carrier gas tube. The second through groove is communicated with the carrier gas through groove. The carrier gas valve is connected to the carrier gas tube and is connected to the control component. The carrier gas tube is connected to the injection outer shell, and the first through groove is communicated with the second through groove; the control component includes a control box, a temperature controller, a circuit board, a power supply, a first solenoid valve switch, and a second solenoid valve switch. The first solenoid valve switch is connected to the carrier gas valve, and the second solenoid valve switch is connected to the split valve. The first solenoid valve switch, the second solenoid valve switch, and the temperature controller are respectively connected to the circuit board. The power supply is connected to the circuit board. The first solenoid valve switch, the second solenoid valve switch, the temperature controller, the circuit board, and the power supply are respectively placed in the control box. The circuit board includes an MCU and a power heating drive circuit. The temperature sensor, the power heating drive circuit, the heating tube, and the temperature controller are respectively connected to the MCU.

2. The split injection system for a gas chromatograph according to claim 1, characterized in that, an injection needle is further connected to the lower part of the lower injection tube. A fourth through groove is provided in the injection needle, and the fourth through groove is communicated with the lower injection through groove; a sealing lower cover is connected to the outside of the lower injection tube, and the sealing lower cover is connected to the lower end of the injection outer shell. An injection needle sealing cover is connected to the outside of the injection needle, and an injection needle support column is connected to the outside of the injection needle sealing cover.

3. The split injection system for a gas chromatograph according to claim 1, characterized in that, the heat insulation and isolation structure includes asbestos.

4. The split injection system for a gas chromatograph according to claim 3, characterized in that, an injection part is further connected to the upper end of the carrier gas screw. An injection port is provided in the injection part, and an injection isolation pad is provided between the injection part and the carrier gas screw.

5. The split injection system for a gas chromatograph according to claim 4, characterized in that, an injection sealing top cover is connected to the outer end of the injection part. A snap spring is provided at the upper end of the injection sealing top cover. The upper end of the injection part extends upward above the injection sealing top cover, and the snap spring is connected to the upper end of the injection part.

6. A working method performed by the split injection system for a gas chromatograph according to any one of claims 1 to 5, Characterized in that, including: The control component controls the heating time and temperature of the heating tube according to the preset temperature control curve PID parameters, and the temperature detected is transmitted to the control component in real time by the temperature sensor. The control component adjusts the heating time and temperature of the heating tube. The control component realizes the split injection control by setting the split ratio or non-split and the opening and closing times of the first solenoid valve switch and the second solenoid valve switch through the program.

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