Hydrogen flame ionization detection device

Abstract

The utility model discloses a hydrogen flame ionization detection device which comprises a top seat, an FID cavity and a base which are sequentially connected from top to bottom, the top seat, the FID cavity and the base are sequentially enclosed to form a combustion cavity which is located in the FID cavity and can be used for combustion, a collecting pipe is arranged in the combustion cavity, the peripheral wall of the collecting pipe is sleeved with an insulating sleeve, and the insulating sleeve is connected with the top seat. A circular-ring-shaped collecting plate is arranged on the peripheral wall of the collecting pipe, insulating gaskets are arranged at the upper end and the lower end of the circular-ring-shaped collecting plate, a horn-shaped opening is formed in the lower end of the collecting pipe, a nozzle is arranged on the base, and the horn-shaped opening of the collecting pipe is arranged around an outlet of the nozzle. The device has the advantages of small detection result error, high sensitivity, high stability and the like.

Description

Technical Field

[0001] The utility model mainly relates to the technical field of FID detectors of gas chromatographs, in particular to a hydrogen flame ionization detection device. Background Technique

[0002] In gas chromatograph detectors, the hydrogen flame ionization detector (FID) is one of the most commonly used general chromatographic detectors, and has a wide range of applications in industries such as petrochemical and food safety detection. It is the best means for gas chromatograph detectors to detect hydrocarbons (such as butane and hexane), and is widely used for the detection of volatile hydrocarbons and many carbon-containing compounds. Its main features are that it responds to almost all volatile organic compounds, the relative response values to all hydrocarbon compounds (carbon number ≥ 3) are almost equal, and the relative response values to homologues (carbon number ≥ 3) in hydrocarbon organic compounds containing heteroatoms are also almost equal, which brings great convenience to the quantification of compounds. Moreover, it has the advantages of high sensitivity, low base current, wide linear range, small dead volume, fast response, can be directly connected with capillary columns, and is insensitive to changes in gas flow rate, pressure and temperature.

[0003] The working principle of FID is to detect the ion current intensity chemically ionized by organic matter under a hydrogen flame. It usually uses hydrogen as the combustion gas, nitrogen as the carrier gas, and air as the combustion-supporting gas. The gas burns at the nozzle inside the cylindrical electrode and generates a voltage. When the carbon-containing solute burns inside the electrode, the generated electrons / ions are collected by the electrode and generate a signal current, and this signal current is collected and transmitted to the A / D conversion module of the computer data acquisition system. In order to achieve the purpose of accurate analysis, FID must have requirements such as high sensitivity, high response, and low error.

[0004] In the existing hydrogen flame ion detectors, the electrodes are arranged up and down relative to the flame, the detection result error is large, and the ion current collection efficiency is low. This structural layout cannot avoid the influence of factors such as working vibration and installation height on the detection result. How to further improve the sensitivity and stability of the detector is a technical problem that needs to be solved urgently by those skilled in the art. Content of the Utility Model

[0005] Aiming at the technical problems existing in the prior art, the utility model provides a hydrogen flame ionization detection device with small detection result error, high sensitivity and high stability.

[0006] To solve the above technical problems, the utility model adopts the following technical solutions:

[0007] A hydrogen flame ionization detection device includes a top seat, an FID cavity, and a base connected in sequence from top to bottom. The top seat, FID cavity, and base enclose a combustion chamber inside the FID cavity for combustion. A collection tube is provided in the combustion chamber. An insulating sleeve is sleeved on the peripheral wall of the collection tube. An annular collection plate is provided on the outer peripheral wall of the collection tube. Insulating gaskets are provided at both the upper and lower ends of the annular collection plate. A flared opening is provided at the lower end of the collection tube. A nozzle is provided on the base, and the flared opening of the collection tube surrounds the outlet of the nozzle.

[0008] As a further improvement of the present utility model: The central axes of the nozzle and the collection tube coincide.

[0009] As a further improvement of the present utility model: The base is provided with a sample gas inlet channel, an air inlet channel, a hydrogen inlet channel, and a tail gas purge inlet channel that communicate with the nozzle.

[0010] As a further improvement of the present utility model: The hydrogen inlet channel and the tail gas purge inlet channel are arranged oppositely on the base.

[0011] As a further improvement of the present utility model: The sample gas inlet channel is arranged above the hydrogen inlet channel and the tail gas purge inlet channel.

[0012] As a further improvement of the present utility model: It further includes a temperature detection mechanism that passes through the base and inserts into the combustion chamber for detecting the temperature inside the combustion chamber.

[0013] As a further improvement of the present utility model: It further includes a heating mechanism that passes through the base and inserts into the combustion chamber.

[0014] As a further improvement of the present utility model: A signal connector is further provided on the FID cavity, and the signal connector is electrically connected to the annular collection plate.

[0015] As a further improvement of the present utility model: The collection tube is cylindrical.

[0016] As a further improvement of the present utility model: The top seat includes a cylindrical hollow tube and a connecting plate. The connecting plate is connected to the FID cavity, and the hollow tube communicates with the combustion chamber for discharging combustion gas and water vapor.

[0017] As a further improvement of the present utility model: A base connecting plate is further provided below the base, and the base connecting plate is used to physically isolate the detector from the instrument housing.

[0018] Compared with the prior art, the advantages of the present utility model are:

[0019] The hydrogen flame ionization detection device of the present utility model is provided with a collection tube in the combustion chamber. An insulating sleeve is sleeved outside the peripheral wall of the collection tube. An annular collection plate is provided at the upper end of the collection tube, and insulating gaskets are provided at both the upper and lower ends of the collection plate. The use of the annular collection plate can effectively increase the area for collecting polarized ions. A flared opening is provided at the lower end of the collection tube, and the flared opening of the collection tube is arranged around the outlet of the nozzle. Since the lower edge of the collection tube is slightly lower than the top end of the nozzle, it can effectively avoid the influence of factors such as working vibration and installation height on the detection result, and can greatly improve the sensitivity and stability of the detection device. Brief Description of the Drawings

[0020] Figure 1 is the explosion view of the present utility model in a specific embodiment.

[0021] Figure 2 is the cross-sectional view of the present utility model in a specific embodiment.

[0022] Figure 3 is the side view of the present utility model in a specific embodiment.

[0023] Figure 4 is the top view of the present utility model in a specific embodiment.

[0024] Figure 5 is the three-dimensional view of the collection tube of the present utility model.

[0025] Legend Explanation:

[0026] 1. Top seat; 101. Hollow tube; 102. Connecting plate; 2. FID cavity; 3. Base; 4. Combustion chamber; 5. Collection tube; 6. Insulating sleeve; 61. Insulating gasket; 7. Annular collection plate; 8. Nozzle; 81. Sample gas inlet channel; 82. Air inlet channel; 83. Hydrogen inlet channel; 84. Tail gas purge inlet channel; 9. Temperature detection mechanism; 10. Heating mechanism; 11. Signal connector; 12. Base connecting plate; 13. Ignition wire base. Detailed Embodiment

[0027] The following will further describe the present utility model in detail with reference to the drawings in the specification and specific embodiments.

[0028] As Figures 1 to 5As shown in the figure, this embodiment discloses a hydrogen flame ionization detection device, which includes a top seat 1, an FID cavity 2, and a base 3 that are connected in sequence from top to bottom. The top seat 1, the FID cavity 2, and the base 3 enclose a combustion chamber 4 inside the FID cavity 2 for combustion. A collection tube 5 is provided in the combustion chamber 4. An insulating sleeve 6 is sleeved outside the peripheral wall of the collection tube 5. An annular collection plate 7 is provided on the outer peripheral wall of the collection tube 5. Insulating gaskets 61 are provided at both the upper and lower ends of the annular collection plate 7. The lower end of the collection tube 5 is provided with a flared opening. A nozzle 8 is provided on the base 3. The flared opening of the collection tube 5 is arranged around the outlet of the nozzle 8.

[0029] In the hydrogen flame ionization detection device of this embodiment, a collection tube 5 is provided in the combustion chamber 4. An insulating sleeve 6 is sleeved outside the peripheral wall of the collection tube 5. An annular collection plate 7 is provided at the upper end of the collection tube 5. Insulating gaskets 61 are provided at both the upper and lower ends of the annular collection plate 7. The use of the annular collection plate 7 can effectively increase the area for collecting polarized ions. The lower end of the collection tube 5 is provided with a flared opening, and the flared opening of the collection tube 5 is arranged around the outlet of the nozzle 8. Since the lower edge of the collection tube 5 is slightly lower than the top end of the nozzle 8, it can effectively avoid the influence of factors such as working vibration and installation height on the detection result, and can greatly improve the sensitivity and stability of the detection device.

[0030] In this embodiment, the central axes of the nozzle 8 and the collection tube 5 coincide. By coordinating an appropriate gas flow ratio, the flame can just be in the combustion chamber 4, and the annular collection plate 7 can better collect the ion current.

[0031] In this embodiment, a sample gas inlet channel 81, an air inlet channel 82, a hydrogen inlet channel 83, and a tail gas purge inlet channel 84 that communicate with the nozzle 8 are provided on the base 3. Further, in a preferred embodiment, the hydrogen inlet channel 83 and the tail gas purge inlet channel 84 are arranged opposite to each other on the base 3, and the sample gas inlet channel 81 is arranged above the hydrogen inlet channel 83 and the tail gas purge inlet channel 84. The hydrogen inlet channel 83 and the tail gas purge inlet channel 84 on the base 3 adopt a relative arrangement design. The sample gas channel 81 after flowing through the chromatographic column is arranged above the confluence of hydrogen and tail gas purge, which can avoid the sample gas being diluted and resulting in residual tailing, and can effectively improve the response sensitivity of the FID detector. By adjusting the column flow rate, the FID detector can quickly detect it. The air inlet channel 82 can ensure that air is evenly distributed around the nozzle 8, and moreover, the combustion air flow can only pass through the collector and discharge the combustion products; by controlling the gas ratio in the four independent inlet channels, the combustion effect of the flame can be conveniently adjusted, and the response sensitivity of the detection device can be improved.

[0032] In this embodiment, the top seat 1 includes a cylindrical hollow tube 101 and a connecting plate 102. The connecting plate 102 is connected to the FID cavity 2, and the hollow tube 101 communicates with the combustion chamber 4 for discharging combustion gas and water vapor. The top seat 1 is designed as a long chimney-type structure with a large inner hole, which can facilitate the discharge of combustion gas and water vapor outside the detection device, avoiding the retention of water vapor inside and affecting the detection result.

[0033] In this embodiment, a temperature detection mechanism 9 (such as a thermocouple) is further included. The temperature detection mechanism 9 passes through the base 3 and inserts into the combustion chamber 4 for detecting the temperature inside the combustion chamber 4.

[0034] In this embodiment, a heating mechanism 10 is further included. The heating mechanism 10 passes through the base 3 and inserts into the combustion chamber 4. The heating mechanism 10 uses a heating rod. The detection device is heated by the heating rod and the temperature is accurately controlled in real time through the thermocouple, ensuring that the temperature of the detection device is set higher than the column temperature, preventing water condensation and pollution of the detection device by combustion products, avoiding an increase in noise, and effectively improving the sensitivity of the detection device.

[0035] In this embodiment, a signal connector 11 is further provided on the FID cavity 2. The signal connector 11 is electrically connected to the annular collecting plate 7. Further, the annular collecting plate 7 is connected to the signal connector 11 by crimping a metal wire.

[0036] In this embodiment, a base connecting plate 12 is further provided below the base 3. The base connecting plate 12 is used to physically isolate the detection device from the instrument housing. Further, in a preferred embodiment, the base connecting plate 12 uses a non-metallic plate with a heat insulation effect, isolating the detection device from the instrument housing. At the same time, a heat insulation cover is further provided outside the detection device to reduce the interference of the outside world on the detector and reduce noise.

[0037] Working principle: When the instrument is working, hydrogen, nitrogen and the sample gas enter the base 3 through the hydrogen inlet channel 83, the make-up gas inlet channel 84 and the sample gas inlet channel 81 respectively. All three inlet channels are connected to the central hole of the base 3. Air can enter the base 3 through the air inlet channel 82 and flow into the combustion chamber 4 from the periphery of the nozzle 8 as the combustion supporting gas. Hydrogen and nitrogen first meet inside the base 3, then flow upward to the sample gas inlet channel 81 above, mix with the sample gas and continue to flow upward to form a columnar flow at the nozzle 8. Subsequently, the columnar flow enters the combustion chamber 4 along the nozzle 8 for combustion. The mixed gas in the combustion chamber 4 is ignited by adjusting the voltage of the ignition wire on the ignition wire base 13; the nozzle 8 is designed to be grounded, the polarization electrode and the collection electrode are designed as one body, the cylindrical collection tube 5 is above the nozzle 8, and the two are coaxially designed, and a polarization voltage is provided at the same time. The heating rod can heat the detection device and accurately control the temperature in real time through the thermocouple to ensure that the temperature of the detection device is set higher than the column temperature. The mixed gas burns in the combustion chamber 4, and the chemically ionized ion flow generates a directional movement under the action of the polarization voltage to form an ion flow, and the intensity of this ion flow is proportional to the carbon content in the sample gas. During the combustion process, the cylindrical collection tube 5 collects the ion flow. The circular collection plate 7 in the middle of the collection tube 5 is connected to the signal connector 11 through a crimped metal wire, and the signal connector 11 is connected to the external acquisition system. At the same time, the combustion gas and water vapor generated by the combustion of the hydrocarbon gas also pass through the hollow tube 101 of the top seat 1 to discharge from the combustion chamber 4, avoiding the residual water vapor inside the equipment. The ion flow captured by the collection tube 5 generates a signal through the high resistance of the amplifier, and after being amplified, it is sent to the data acquisition system. The ion flow is converted into a digital signal by the electrometer in the acquisition system to achieve A / D conversion, and finally it is output by the current output device.

[0038] The above is only the preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements should be regarded as the protection scope of the present invention.

Claims

1. A hydrogen flame ionization detection device, comprising a top seat (1), a FID cavity (2) and a base (3) connected in sequence from top to bottom, wherein the top seat (1), the FID cavity (2) and the base (3) are sequentially enclosed to form a combustion cavity (4) located inside the FID cavity (2) for combustion, characterized in that: A collecting pipe (5) is provided in the combustion chamber (4), an insulating sleeve (6) is provided on the outer wall of the collecting pipe (5), an annular collecting plate (7) is provided on the outer wall of the collecting pipe (5), an insulating gasket (61) is provided at the upper and lower ends of the annular collecting plate (7), a trumpet-shaped opening is provided at the lower end of the collecting pipe (5), a nozzle (8) is provided on the base (3), and the trumpet-shaped opening of the collecting pipe (5) is arranged around the outlet of the nozzle (8).

2. The hydrogen flame ionization detection device according to claim 1, characterized in that: The central axes of the nozzle (8) and the collecting tube (5) coincide with each other.

3. The hydrogen flame ionization detection device according to claim 2, characterized in that: The base (3) is provided with a sample gas inlet channel (81), an air inlet channel (82), a hydrogen inlet channel (83) and a tail gas inlet channel (84) which are connected to the nozzle (8).

4. The hydrogen flame ionization detection device according to claim 3, characterized in that: The hydrogen gas inlet passage (83) and the tail gas inlet passage (84) are arranged on the base (3) in a manner opposite to each other.

5. The hydrogen flame ionization detection device according to claim 3, characterized in that: The sample gas inlet channel (81) is arranged above the hydrogen inlet channel (83) and the tail gas inlet channel (84).

6. The hydrogen flame ionization detection device according to any one of claims 1 to 5, characterized in that: It also comprises a temperature detection mechanism (9), which passes through the base (3) and is inserted into the combustion chamber (4) to detect the temperature in the combustion chamber (4).

7. The hydrogen flame ionization detection device according to any one of claims 1 to 5, characterized in that: It also comprises a heating mechanism (10), wherein the heating mechanism (10) passes through the base (3) and is inserted into the combustion chamber (4).

8. The hydrogen flame ionization detection device according to any one of claims 1 to 5, characterized in that: A signal connector (11) is also provided on the FID cavity (2), and the signal connector (11) is electrically connected to the annular collecting plate (7).

9. The hydrogen flame ionization detection device according to any one of claims 1 to 5, characterized in that: The collecting tube (5) is cylindrical.

10. The hydrogen flame ionization detection device according to any one of claims 1 to 5, characterized in that: The top seat (1) comprises a cylindrical hollow tube (101) and a connecting plate (102); the connecting plate (102) is connected to the FID chamber (2); and the hollow tube (101) is connected to the combustion chamber (4) for discharging combustion gas and water vapor.

11. The hydrogen flame ionization detection device according to any one of claims 1 to 5, characterized in that: A base connecting plate (12) is also provided below the base (3), and the base connecting plate (12) is used to physically isolate the detector from the instrument casing.

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