Portable dimethyl ether chromatographic analyzer

Abstract

The utility model relates to a portable dimethyl ether chromatographic analyzer which comprises a ballast gas supply unit, a detection gas sampling unit, a six-way valve, a chromatographic column, a PID (Proportion Integration Differentiation) detector, an exhaust unit and a quantitative tube, the ballast air supply unit is in an embedded type and comprises a high-pressure air pump, a one-way valve, a first filter, an air storage chamber, a pressure sensor and a first electronic pressure flow controller, the high-pressure air pump provides air with high enough pressure, and the first filter is used for primarily purifying the air flowing through the high-pressure air pump; dust and water vapor in the air are removed; the gas pressure in the gas storage chamber is maintained within a certain pressure range, a carrier gas source with constant pressure is provided for a gas chromatographic gas circuit, and normal operation of the portable chromatographic instrument can be realized without external gas supply, so that the requirement that a traditional portable chromatographic instrument needs an external carrier gas bottle or other carrier gas sources to provide carrier gas is met.

Description

Technical Field

[0001] The utility model relates to the field of gas detection, in particular to a portable dimethyl ether chromatographic analyzer. Background Art

[0002] Dimethyl ether is a flammable and explosive gas that is highly corrosive to rubber, easily causing the rubber seals of liquefied petroleum gas (LPG) cylinders to fail and leading to LPG leaks. The addition of dimethyl ether to LPG poses a significant safety risk. The GB 11174-2011 "Liquefied Petroleum Gas" standard stipulates that the main component must be present at least 95% of the gas and explicitly prohibits the addition of non-hydrocarbon components other than odorants. Dimethyl ether is a non-hydrocarbon component in this context. In August 2023, the State Council's Work Safety Committee issued the "Special Plan for Gas Management Departments to Conduct National Urban Gas Safety Special Rectification." This plan calls for strengthened management and increased penalties for issues such as substandard pipeline gas odorization (tetrahydrothiophene) and the illegal addition of dimethyl ether to liquefied gas.

[0003] GB 11174-2011 specifies gas chromatography as the standard method for detecting dimethyl ether in liquefied petroleum gas. The greatest advantages of portable gas chromatographs over traditional gas chromatographs lie in their portability and flexibility. Traditional gas chromatographs are bulky and complex to operate, typically requiring fixed laboratory use. Gas chromatographs, however, are compact and can be easily transported to external locations for analysis, even for real-time field monitoring. Therefore, portable gas chromatographs are widely used for industrial field testing. Existing portable gas chromatographs typically use an external carrier gas cylinder and pressure control valve to provide carrier gas, often using high-purity inert gases such as nitrogen and argon. This technical solution has several drawbacks: high operating costs; a split design, large size, and inconvenient portability; and, as the carrier gas depletes, regular on-site replacement is required.

[0004] In order to solve the above problems, people have been seeking an ideal technical solution. Summary of the Invention

[0005] The purpose of the utility model is to provide a portable dimethyl ether chromatographic analyzer in view of the deficiencies in the prior art.

[0006] In order to achieve the above-mentioned object, the technical solution adopted by the utility model is: a portable dimethyl ether chromatograph analyzer, comprising a pressurized gas supply unit, a detection gas sampling unit, a six-way valve, a chromatographic column, a PID detector, an exhaust unit and a quantitative tube;

[0007] The pressurized carrier gas supply unit is connected to the first port of the six-way valve;

[0008] The detection gas sampling unit is connected to the third port of the six-way valve;

[0009] The exhaust unit is connected to the fourth port of the six-way valve;

[0010] The chromatographic column is connected to the sixth port of the six-way valve;

[0011] The quantitative tube is connected in series between the second port and the fifth port of the six-way valve;

[0012] The PID detector is in communication with the chromatographic column box;

[0013] The pressurized gas supply unit includes a high-pressure air pump, a one-way valve, a first filter, an air storage chamber, a pressure sensor and a first electronic pressure flow controller; the high-pressure air pump is connected to the air inlet of the first filter through the one-way valve, and the air outlet of the first filter is connected to the air inlet of the air storage chamber, and the pressure sensor is arranged in the air storage chamber; the air outlet of the air storage chamber is connected to the first port of the six-way valve through the first electronic pressure flow controller.

[0014] Furthermore, the pressurized gas supply unit also includes a base, and the top surface of the base is provided with two through holes, wherein the air storage chamber is installed in one of the through holes, and the first filter is installed in the other through hole; a base air inlet and a base air outlet are provided on the side of the base, the air inlet of the first filter is connected to the base air inlet through an air guide channel, the air outlet of the first filter is connected to the air inlet of the air storage chamber through the air guide channel, and the air outlet of the air storage chamber is connected to the base air outlet.

[0015] Furthermore, the chromatographic column box includes a chromatographic column box shell and a second cover plate detachably connected to the chromatographic column box shell, the chromatographic column box shell is provided with a chromatographic column box air inlet and a chromatographic column box air outlet, the PID detector is installed on the second cover plate, the chromatographic column box shell is provided with an insulation layer and a chromatographic column cavity, the chromatographic column cavity is provided with a chromatographic column, one end of the chromatographic column is connected to the air inlet of the PID detector, and the other end is connected to the air inlet of the chromatographic column box; the air outlet of the PID detector is connected to the air outlet of the chromatographic column box.

[0016] The present invention has substantial features and progress compared with the prior art. Specifically, the present invention has an embedded pressurized carrier gas supply unit, which includes a high-pressure air pump, a one-way valve, a first filter, an air storage chamber, a pressure sensor and a first electronic pressure flow controller. The high-pressure air pump provides air with a sufficiently high pressure. The first filter preliminarily purifies the air flowing through the high-pressure air pump to remove dust and water vapor in the air; the gas pressure in the air storage chamber is maintained within a certain pressure range, providing a carrier gas source with constant pressure for the gas chromatography gas circuit, and the normal operation of the portable chromatograph can be achieved without external gas supply, thereby solving the need for traditional portable chromatographs to provide carrier gas with an external carrier gas bottle or other carrier gas source, making the device smaller and more portable; no nitrogen and argon are required, and air can be used, which is low cost; and as the carrier gas is gradually consumed, it can be automatically replenished, and there is no need for people to replace the carrier gas bottle regularly.

[0017] In addition, in the present invention, the first filter and the gas storage chamber are modularly designed, and the chromatographic column and the PID detector are also modularly designed. The modular design further reduces the volume of the portable dimethyl ether chromatograph. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural diagram of the utility model;

[0019] Figure 2 for Figure 1 Schematic diagram of the structure after structure switching;

[0020] Figure 3 It is a schematic diagram of the overall structure of the pressurized gas supply unit;

[0021] Figure 4 Schematic diagram of the overall structure of the chromatographic column and PID detector.

[0022] In the figure: 1. High-pressure air pump; 2. One-way valve; 3. First filter; 4. Air storage chamber; 5. Pressure sensor; 6. First electronic pressure flow controller; 7. Six-way valve; 8. Second filter; 9. Second electronic pressure flow controller; 10. Chromatographic column; 11. PID detector; 12. Exhaust unit; 13. Quantitative tube; 14. Base; 15. Base air inlet; 16. Base air outlet; 17. First cover; 18. Filter body; 19. Chromatographic column box housing; 20. Insulation layer; 21. Second cover; 22. Chromatographic column box air inlet; 23. Chromatographic column box air outlet; 24. PID detector air inlet; 25. Chromatographic column cavity. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for the purpose of explaining the present invention and are not intended to limit the present invention. That is, the embodiments described herein are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein can be arranged and designed in a variety of different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0025] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0026] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0027] Example 1

[0028] This embodiment provides a portable dimethyl ether chromatographic analyzer, such as Figure 1-2 As shown, it includes a pressurized carrier gas supply unit, a detection gas sampling unit, a six-way valve 7, a chromatographic column 10, a PID detector 11, an exhaust unit 12 and a quantitative tube 13;

[0029] The pressurized carrier gas supply unit is connected to the first port of the six-way valve 7;

[0030] The detection gas sampling unit is connected to the third port of the six-way valve 7;

[0031] The exhaust unit 12 is connected to the fourth port of the six-way valve 7;

[0032] The chromatographic column 10 is connected to the sixth port of the six-way valve 7;

[0033] The quantitative pipe 13 is connected in series between the second port and the fifth port of the six-way valve 7;

[0034] The PID detector 11 is in communication with the chromatographic column 10;

[0035] The pressurized gas supply unit includes a high-pressure air pump 1, a one-way valve 2, an air storage chamber 4, a pressure sensor 5 and a first electronic pressure flow controller 6; the high-pressure air pump 1 is connected to the air inlet of the air storage chamber 4 through the one-way valve 2, and the pressure sensor 5 is arranged in the air storage chamber 4; the air outlet of the air storage chamber 4 is connected to the first port of the six-way valve 7 through the first electronic pressure flow controller 6.

[0036] Preferably, the detection gas sampling unit includes a second filter 8 and a second electronic pressure flow controller 9, which are connected in sequence. The second filter 8 can filter out moisture and dust from the sample gas to be detected, thereby extending the service life of the dimethyl ether chromatograph and improving detection accuracy. The second electronic pressure flow controller 9 is used to stabilize the pressure and flow of the sample gas to be detected. Preferably, the second filter 8 is a polytetrafluoroethylene filter element.

[0037] It can be understood that the portable dimethyl ether chromatograph is also provided with a control system, which is connected to the one-way valve 2, the pressure sensor 5, the high-pressure air pump 1, the six-way valve 7, the PID detector 11 and the second electronic pressure flow controller 9.

[0038] Before use, the control system controls the high-pressure air pump 1 to pump air into the air storage chamber 4 through the one-way valve 2. The pressure sensor 5 is used to detect the pressure of the gas in the air storage chamber 4. When the pressure of the gas in the air storage chamber 4 is lower than a first preset value, the control system controls the high-pressure air pump 1 to start working. When the pressure of the gas in the air storage chamber 4 is higher than a second preset value, the control system controls the high-pressure air pump 1 to stop working.

[0039] In the initial state, if Figure 1 As shown, the first port of the six-way valve 7 is connected to the sixth port, the second port is connected to the third port, and the fourth port is connected to the fifth port, that is, the quantitative tube 13 is connected to the detection gas sampling unit and the exhaust unit 12; when sampling is required, the control system controls the second electronic pressure flow controller 9 to open, and the sample gas to be tested is stabilized by the second electronic pressure flow controller 9 to form an airflow with stable pressure and flow, which enters the quantitative tube 13 for quantitative sampling, and the excess gas is discharged from the emptying unit.

[0040] When sampling is completed and analysis is required, the control system turns off the second electronic pressure flow controller 9. When the flow of the second electronic pressure flow controller 9 drops to 0, the control system controls the six-way valve 7 to switch the state, such as Figure 2 As shown, at this time, the first port of the six-way valve 7 is connected to the second port, the third port is connected to the fourth port, and the fifth port is connected to the sixth port, that is, the quantitative tube 13 is connected to the pressurized gas supply unit and the chromatographic column 10.

[0041] The control system also controls the first electronic pressure flow controller 6 to open, and the carrier gas carries the sample gas quantitatively sampled in the quantitative tube 13 into the chromatographic column 10 for component separation. After flowing out of the chromatographic column 10, it enters the PID detector 11 for detection, thereby obtaining the gas concentration of the sample gas to be tested.

[0042] In particular, conventional chromatographs use nitrogen, argon, etc. as carrier gases, which need to be stored in cylinders, are expensive and heavy, and are very inconvenient for portable products. Moreover, when traditional chromatographs detect the gas source, they worry about the oxidation effect of oxygen on the components, as well as the oxidation effect in the detector. The present application is used to detect liquefied petroleum gas. Since the gas components in the air have very low interference with the liquefied petroleum gas and will not affect the analysis of the liquefied petroleum gas components, air is used as the carrier gas, which is low in cost and can be generated at any time, so it does not need to be replaced regularly or carried in large quantities. The detector uses a PID photoionization detector, and after voltage and flow stabilization, it can provide the instrument with a gas source, which can be applied in a variety of complex scenarios.

[0043] Compared with the method of directly using an air pump to extract air to provide carrier gas for chromatographic analysis, the utility model is provided with an air storage chamber 4 and a pressure sensor 5, and the pressure sensor 5 is used to maintain the gas pressure in the air storage chamber 4 within a certain pressure range. Only when the pressure in the air storage chamber 4 is not within the certain pressure range, the high-pressure air pump 1 is controlled to work, thereby realizing intermittent operation of the high-pressure air pump 1 and extending its service life.

[0044] In addition, the present invention is further provided with a one-way valve 2, which can control the one-way flow of air to prevent air from escaping from the end of the high-pressure air pump 1 due to the high-pressure air pump 1 stopping operation.

[0045] Further, such as Figure 3As shown, the pressurized gas supply unit also includes a base 14, and the top surface of the base 14 is provided with two through holes, one of which is equipped with the air storage chamber 4, and the other is equipped with the first filter 3; a base air inlet 15 and a base air outlet 16 are provided on the side of the base 14, the air inlet of the first filter 3 is connected to the base air inlet 15 through an air guide channel, the air outlet of the first filter 3 is connected to the air inlet of the air storage chamber 4 through the air guide channel, and the air outlet of the air storage chamber 4 is connected to the base air outlet 16.

[0046] It is understandable that the first filter 3 is provided in front of the air storage chamber 4 so as to purify the air flowing through the high-pressure air pump 1 to ensure that the air in the air storage chamber 4 is clean air.

[0047] It should be noted that the first filter 3 includes a filter body 18 of a specific filter cavity and a first cover plate 17 detachably connected to the filter body 18. A filter element is installed in the filter cavity. Preferably, the filter element includes a polytetrafluoroethylene filter element, a molecular sieve filter element, an activated carbon filter element and / or a color-changing silica gel filter element to purify organic matter, sulfide, water vapor and other components in the air.

[0048] During use, the filter element installed in the first filter 3 can be adjusted accordingly based on the chromatographic analysis target. Different filter elements provide clean air as carrier gas for subsequent chromatographic analysis, eliminating detection errors caused by impurities in the carrier gas. Specifically, when the filter element needs to be adjusted, the first cover 17 can be opened to conveniently and quickly replace the filter element.

[0049] Of course, as the filter element is used for a long time, the aging of the filter material will affect the purification effect, and even reverse leakage will occur, which will increase the harmful substances in the air. Therefore, it is also necessary to regularly open the first cover 17 to replace the filter element.

[0050] It can be seen that in this embodiment, the first filter 3 and the air storage chamber 4 are integrated together through the base 14 to form a modular design with a small size. When the first filter 3 or the air storage chamber 4 fails, only the corresponding module needs to be replaced, which is convenient and quick.

[0051] Furthermore, the chromatographic column 10 and the PID detector 11 also adopt a modular design. In one embodiment, the chromatographic column 10 is arranged in a chromatographic column box, and the PID detector 11 is arranged on the chromatographic column box and is connected to the chromatographic column 10.

[0052] Specifically, such as Figure 4As shown, the chromatographic column box includes a chromatographic column box shell 19 and a second cover plate 21 detachably connected to the chromatographic column box shell 19, the chromatographic column box shell 19 is provided with a chromatographic column box air inlet 22 and a chromatographic column box air outlet 23, the PID detector 11 is installed on the second cover plate 21, and the air outlet of the PID detector 11 is connected to the chromatographic column box air outlet 23; the chromatographic column box shell 19 is provided with an insulation layer 20 and a chromatographic column cavity 25, and the chromatographic column cavity 25 is provided with a chromatographic column 10, one end of the chromatographic column 10 is connected to the air inlet 24 of the PID detector, and the other end is connected to the chromatographic column box air inlet 22.

[0053] Similarly, the chromatographic column 10 can be adjusted based on testing requirements. For example, if sulfide detection is required, a sulfur analysis column module can be installed to achieve precise separation, analysis, and detection of sulfides such as ethyl mercaptan, CS2, and tetrahydrothiophene. For the addition and detection of emerging sulfur-free odorants (methyl acrylate and ethyl acrylate) in natural gas, a dedicated acrylic acid analysis column module can be installed to accurately analyze and detect these sulfur-free odorants. Adjustments to the chromatographic column 10 can be made by opening the second cover 21.

[0054] It is understandable that a heating device and a temperature control device are further provided on the outside of the chromatographic column 10. The heating device is used to heat the chromatographic column 10. Preferably, the temperature control device includes a platinum resistance temperature sensor for controlling the temperature of the chromatographic column 10 according to the real-time detected temperature.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model and not to limit it; although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the utility model can still be modified or some technical features can be replaced by equivalents; without departing from the spirit of the technical solution of the utility model, they should all be included in the scope of the technical solution for which protection is requested in the utility model.

Claims

1. A portable dimethyl ether chromatograph, characterized in that: It includes a pressurized carrier gas supply unit, a detection gas injection unit, a six-way valve, a chromatographic column, a PID detector, an exhaust unit and a quantitative tube; The pressurized carrier gas supply unit is connected to the first port of the six-way valve; The detection gas sampling unit is connected to the third port of the six-way valve; The exhaust unit is connected to the fourth port of the six-way valve; The chromatographic column is connected to the sixth port of the six-way valve; The quantitative tube is connected in series between the second port and the fifth port of the six-way valve; The PID detector is in communication with the chromatographic column box; The pressurized gas supply unit includes a high-pressure air pump, a one-way valve, a first filter, an air storage chamber, a pressure sensor and a first electronic pressure flow controller; the high-pressure air pump is connected to the air inlet of the first filter through the one-way valve, and the air outlet of the first filter is connected to the air inlet of the air storage chamber, and the pressure sensor is arranged in the air storage chamber; the air outlet of the air storage chamber is connected to the first port of the six-way valve through the first electronic pressure flow controller.

2. A portable dimethyl ether chromatograph according to claim 1, characterized in that: The pressurized gas supply unit also includes a base, and the top surface of the base is provided with two through holes, one of which is equipped with the air storage chamber, and the other is equipped with the first filter; a base air inlet and a base air outlet are provided on the side of the base, the air inlet of the first filter is connected to the base air inlet through an air guide channel, the air outlet of the first filter is connected to the air inlet of the air storage chamber through an air guide channel, and the air outlet of the air storage chamber is connected to the base air outlet.

3. A portable dimethyl ether chromatograph according to claim 1 or 2, characterized in that: The first filter comprises a filter body with a specific filter cavity and a first cover plate detachably connected to the filter body, and a filter element is installed in the filter cavity.

4. The portable dimethyl ether chromatograph according to claim 1, characterized in that: The chromatographic column box includes a chromatographic column box shell and a second cover plate detachably connected to the chromatographic column box shell, the chromatographic column box shell is provided with a chromatographic column box air inlet and a chromatographic column box air outlet, the PID detector is installed on the second cover plate, the chromatographic column box shell is provided with an insulation layer and a chromatographic column cavity, the chromatographic column is provided in the chromatographic column cavity, one end of the chromatographic column is connected to the air inlet of the PID detector, and the other end is connected to the air inlet of the chromatographic column box; the air outlet of the PID detector is connected to the air outlet of the chromatographic column box.

5. The portable dimethyl ether chromatograph according to claim 1, characterized in that: The detection gas sampling unit includes a second filter and a second electronic pressure flow controller which are connected in sequence.

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