CN-121994981-A - Trace gas inlet device and method suitable for front end of gas chromatograph

CN121994981ACN 121994981 ACN121994981 ACN 121994981ACN-121994981-A

Abstract

The invention relates to the technical field of gas analysis, in particular to a trace gas inlet device and a trace gas inlet method suitable for the front end of a gas chromatograph, wherein the device comprises a sample tank assembly, a vacuum system, a cryogenic unit, a pulse flushing system, a flow path control assembly and a residual sample storage assembly; the sample tank component is used for fixing a copper pipe for containing trace gas through the copper pipe fixer, the vacuum system is used for vacuumizing and eliminating interference, the cryogenic unit is used for realizing complete release of gas through low-temperature enrichment, the pulse flushing system is used for cleaning a pipeline, the flow path control component is used for accurately distributing the gas flow direction through the three-way flow dividing valve, and the residual sample storage component is used for transferring residual gas to the external gas storage tank through the micro sucking pump. The device realizes high-efficiency nondestructive sample injection of a trace amount of closed gas sample, improves analysis precision and reliability, supports multiple rechecks of the sample, can be used for seamlessly connecting the conventional gas chromatograph, and has important practical value for strategic gas resource exploration and analysis of helium, natural hydrogen and the like.

Inventors

SHEN BIN
HU CAIZHI
FANG XINXIN
YANG JIAJIA
YUAN KUN
XU XUEMIN
ZHANG XIAOTAO
FANG PENG
Zhai jia
XU ZHICHAO
QIN JING

Assignees

国家地质实验测试中心

Dates

Publication Date: 20260508
Application Date: 20260203

Claims (10)

1. A micro gas inlet device suitable for a front end of a gas chromatograph, comprising: the sample tank assembly comprises a sample tank cavity, a sealing cover for sealing the sample tank cavity and a copper pipe fixer arranged in the sample tank cavity, wherein the copper pipe fixer is used for fixing a copper pipe for containing trace gas; the vacuum system is communicated with the sample tank cavity and is used for vacuumizing the sample tank cavity and related pipelines; A cryogenic unit comprising a cold trap for receiving the sample tank assembly and cooling the sample tank cavity and a temperature controller for controlling a cooling temperature; the pulse flushing system is communicated with the air outlet of the sample tank cavity and is used for introducing pulse air flow into a pipeline connected with the gas chromatograph for flushing; The flow path control assembly comprises a three-way diverter valve, a first port of the three-way diverter valve is connected to an air outlet of the sample tank cavity, a second port of the three-way diverter valve is connected to a sample inlet of the gas chromatograph through a sample injection connecting pipe, and a third port of the three-way diverter valve is connected to a residual sample sampling interface; and the residual sample storage assembly comprises a miniature air pump, wherein the miniature air pump is connected to the residual sample sampling interface and is used for transferring residual gas to an external air storage tank.
2. The micro gas inlet device for the front end of the gas chromatograph according to claim 1, wherein the vacuum system comprises a high vacuum molecular pump, a vacuum valve and a pressure sensor, and the pressure sensor is used for monitoring the pressure in the sample tank cavity in real time.
3. The trace gas inlet device suitable for the front end of the gas chromatograph, which is disclosed in claim 1, is characterized in that the cryogenic unit is a liquid nitrogen cold trap, the temperature control precision of the temperature controller is +/-0.5 ℃, and an embedded temperature sensor is arranged on the inner wall of the liquid nitrogen cold trap.
4. The micro gas inlet device for the front end of the gas chromatograph according to claim 1, wherein the pulse flushing system comprises a programmable pulser, a gas source and a pressure regulating valve, wherein the programmable pulser is used for controlling the gas source to intermittently introduce gas into the pipeline at a set pulse frequency, pulse pressure and pulse duration.
5. The micro-gas inlet device suitable for the front end of the gas chromatograph according to claim 1, wherein the pulse frequency of the pulse flushing system is set to be 1-5Hz, the pulse pressure is controlled to be 0.2-0.8MPa, and the single pulse duration is 5-15s.
6. The micro gas inlet device for the front end of the gas chromatograph according to claim 1, wherein the side wall of the sample tank assembly is provided with a screw-in tube breaking device, and the tube breaking device comprises a hard alloy spike for piercing the tube wall of the copper tube fixed on the copper tube holder.
7. The micro gas inlet device suitable for the front end of the gas chromatograph according to claim 1, further comprising a PLC control system, wherein the PLC control system is in signal connection with the vacuum system, the cryogenic unit, the pulse flushing system, the flow path control assembly and the residual sample storage assembly, and is used for realizing semiautomatic linkage control.
8. A micro-gas inlet method using the device according to any one of claims 1 to 7, comprising the steps of: S1, fixing a copper pipe filled with trace gas on the copper pipe fixer and placing the copper pipe into a sample tank cavity, and starting a vacuum system to vacuumize the sample tank cavity to a preset vacuum degree after sealing; s2, operating a pipe breaking device to pierce the copper pipe, placing the sample tank assembly in the cold trap and connecting the sample tank assembly in a sealing way, starting the cryogenic unit to cool the sample tank cavity to a target temperature, liquefying matrix components in a gas sample, and enriching trace components; S3, switching the flow path control assembly to enable the sample tank cavity to be communicated with a gas chromatograph sample inlet, starting the pulse flushing system to perform pulse flushing on a sample inlet pipeline, and introducing a gas sample into the gas chromatograph for analysis after flushing is completed; and S4, after analysis is completed, switching the flow path control assembly to enable the sample tank cavity to be communicated with the residual sample sampling interface, and starting the residual sample storage assembly to transfer residual gas in the sample tank cavity to an external gas storage tank for storage.
9. The method according to claim 8, wherein the predetermined vacuum degree is 10 -2 Pa or less, and the precession rate of the pipe breaking device is not more than 1mm/S in step S2.
10. The method according to claim 8, wherein in step S3, the pulse flushing cycle is 3-8 times and the pulse interval is 5 seconds, and in step S4, before the residual gas is transferred, the sample tank cavity is heated to room temperature to completely gasify the liquefied gas.

Description

Trace gas inlet device and method suitable for front end of gas chromatograph Technical Field The invention relates to the technical field of gas analysis, in particular to a trace gas inlet device and a trace gas inlet method suitable for the front end of a gas chromatograph. Background The gas chromatography technology is the most common and widely accepted gas component analysis method at present, and plays a key role in various fields such as environmental monitoring, petrochemical industry, biological medicine, food safety and the like. The conventional sample injection mode of the gas chromatograph, such as manual sample injection or valve sample injection, can better cope with the sample injection requirement of the gas sample in the container such as the air bag, the steel bottle or the brine bottle, but the sample volume is usually required to be not less than 20mL so as to ensure the accuracy and the repeatability of analysis. In recent years, with the remarkable increase of the requirements of exploration of new strategic energy resources such as helium, natural hydrogen and the like, the efficient analysis of the gas components with low molecular weight, easy volatilization, trace existence and extremely small sampling volume is presented with new challenges. In order to ensure the tightness and the component stability of the gas in the sampling and conveying process, copper pipes with low adsorptivity, good sealing performance and easy transportation are often adopted as sampling and temporary storage containers. However, the existing gas chromatography sample injection system is not adapted to the micro-scale and closed sample containers, so that sample injection operation cannot be directly carried out, and high-precision analysis capability of micro-scale gas components in the related field is severely limited. Therefore, development of a front-end device and a front-end method which can be in seamless connection with the existing gas chromatography system and are suitable for micro-closed gas sample injection is needed, so that urgent requirements for high-precision gas component analysis in the process of exploration and evaluation of emerging energy resources such as helium, natural hydrogen and the like can be met, long-term problems that the micro-gas samples are difficult to store and transport can be effectively solved, and important practical significance is provided for improving analysis efficiency, data reliability and resource evaluation accuracy. Disclosure of Invention The invention aims to provide a trace gas inlet device and a trace gas inlet method suitable for the front end of a gas chromatograph, which can solve the technical problems. The invention provides a trace gas inlet device suitable for the front end of a gas chromatograph, which comprises: the sample tank assembly comprises a sample tank cavity, a sealing cover for sealing the sample tank cavity and a copper pipe fixer arranged in the sample tank cavity, wherein the copper pipe fixer is used for fixing a copper pipe for containing trace gas; the vacuum system is communicated with the sample tank cavity and is used for vacuumizing the sample tank cavity and related pipelines; A cryogenic unit comprising a cold trap for receiving the sample tank assembly and cooling the sample tank cavity and a temperature controller for controlling a cooling temperature; the pulse flushing system is communicated with the air outlet of the sample tank cavity and is used for introducing pulse air flow into a pipeline connected with the gas chromatograph for flushing; The flow path control assembly comprises a three-way diverter valve, a first port of the three-way diverter valve is connected to an air outlet of the sample tank cavity, a second port of the three-way diverter valve is connected to a sample inlet of the gas chromatograph through a sample injection connecting pipe, and a third port of the three-way diverter valve is connected to a residual sample sampling interface; and the residual sample storage assembly comprises a miniature air pump, wherein the miniature air pump is connected to the residual sample sampling interface and is used for transferring residual gas to an external air storage tank. Preferably, the vacuum system comprises a high-vacuum molecular pump, a vacuum valve and a pressure sensor, wherein the pressure sensor is used for monitoring the pressure in the sample tank cavity in real time, and a thermometer is arranged on the sample tank cavity. Preferably, the cryogenic unit is a liquid nitrogen cold trap, the temperature control precision of the temperature controller is +/-0.5 ℃, and an embedded temperature sensor is arranged on the inner wall of the liquid nitrogen cold trap. Preferably, the pulse flushing system comprises a programmable pulser, a gas source and a pressure regulating valve, wherein the programmable pulser is used for controlling the gas source to intermittently feed gas into the pipeli