CN115343391A - System and method for chromatographic analysis of isotopic gas components - Google Patents
System and method for chromatographic analysis of isotopic gas components Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/60—Construction of the column
- G01N30/6034—Construction of the column joining multiple columns
- G01N30/6039—Construction of the column joining multiple columns in series
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/86—Signal analysis
- G01N30/8675—Evaluation, i.e. decoding of the signal into analytical information
Abstract
The embodiment of the invention discloses a chromatographic analysis system for isotopic gas components. The system comprises: the sample injection assembly is used for receiving quantitative sample gas, and the sample gas comprises sample components and impurity components; the pre-separation column is used for receiving the sample gas carried by the first carrier gas in the sample feeding assembly and separating the sample component from the impurity component in the sample gas; a separation column for receiving the sample components separated by the pre-separation column, the separation column being disposed in a liquid nitrogen storage container, the separation column being configured to separate each isotope component in the sample components at a temperature of the liquid nitrogen; a chromatographic detector connected to the separation column for detecting and analyzing the gas components entering therein; and the switching device is respectively connected with the sample injection assembly, the pre-separation column and the separation column and is used for switching the gas circuit connection so as to control the communication and the cut-off among the sample injection assembly, the pre-separation column and the separation column. In addition, the invention also provides a chromatographic analysis method of the isotope gas components.
Description
Technical Field
The embodiment of the invention relates to the technical field of chromatographic analysis, in particular to a chromatographic analysis system and method for isotopic gas components.
Background
At present, tritium online measurement methods comprise an ionization chamber, raman spectroscopy, mass spectrometry and the like, but the analysis effects of the methods are not ideal. Helium isotope detection generally employs mass spectrometry, which mainly uses the difference in charge-to-mass ratio of molecules or atoms for separation. However, helium-3 is produced by hydrogen isotopes, and hydrogen isotopes, particularly HT molecules and free T atoms, affect the measurement results of helium-4 and helium-3, respectively, during mass spectrometry.
In contrast, chromatography can effectively and accurately distinguish between a hydrogen isotope component and a helium isotope component, but the existing chromatographic analysis system has low detection accuracy due to the impurity components contained in the sample.
Disclosure of Invention
According to one aspect of the present invention, a system for chromatographic analysis of isotopic gas components is provided. It includes: a sample introduction assembly configured to receive a quantitative sample gas, the sample gas comprising a sample component and an impurity component; a pre-separation column for receiving the sample gas carried by the first carrier gas in the sample introduction assembly and separating a sample component from an impurity component in the sample gas; a separation column for receiving the sample components separated by the pre-separation column, the separation column being disposed in a liquid nitrogen storage container, the separation column being configured to separate each isotope component in the sample components at a liquid nitrogen temperature; a chromatographic detector connected to the separation column for detecting the gas component entering it for analysis; and the switching device is respectively connected with the sample injection assembly, the pre-separation column and the separation column, and is used for switching gas circuit connection so as to control the communication and the cut-off among the sample injection assembly, the pre-separation column and the separation column.
According to another aspect of the present invention, a method of chromatographic analysis of isotopic gas components is provided. The method is implemented using a chromatographic analysis system of isotopic gas components according to the embodiments described above. The method comprises the following steps: quantitatively feeding a sample gas into a pre-separation column, wherein the pre-separation column separates and separates sample components and impurity components in the sample gas; conveying the sample component flowing out of the pre-separation column into a separation column, and separating the sample component by the separation column to obtain each isotope component; conveying each separated isotope component to a detector, and detecting by the detector to obtain a characteristic peak of each isotope component; determining the abundance of each isotopic component in the sample gas according to the intensity of each characteristic peak.
Drawings
Other objects and advantages of the present invention will become apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, which are set forth to provide a thorough understanding of the present invention.
FIG. 1 is a schematic diagram of a chromatography system according to an embodiment of the invention in a first operating state.
FIG. 2 is a schematic diagram of a chromatography system according to an embodiment of the invention in a second operating state.
Fig. 3 to 7 are views showing D in hydrogen isotope gas according to an embodiment of the present invention 2 、H 2 HT, DT and T 2 The standard condition partial pressure of the components is linearly fitted to the peak height.
Fig. 8 is a chromatogram of a hydrogen isotope sample gas according to an embodiment of the present invention.
Fig. 9 is a linear plot of characteristic peak area versus feed pressure for He-3 components in a mixed gas of He-3 at different concentrations according to one embodiment of the present invention.
It is to be noted that the drawings are not necessarily drawn to scale but are merely shown in a schematic manner which does not detract from the understanding of the reader.
Description of the reference numerals:
11. a sample inlet; 111. a sample injection valve; 12. a quantitative section; 13. a control valve, 14, a permeate; 15. a pressure sensor;
20. pre-separation column; 30. a separation column; 31. a liquid nitrogen storage container; 40. a chromatographic detector; 50. a switching device; 51. a blocking member;
60. a carrier gas control device 61, a first carrier gas path; 611. a carrier gas switching valve; 612. a carrier gas interface; 62. a second carrier gas path; 63. a third carrier gas path; 64. a fourth carrier gas path;
70. a vacuum pump; 71. an air extraction pipeline; 72. a vacuum switching valve; 73. and a vacuum interface.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be described below in detail and completely with reference to the accompanying drawings of the embodiments of the present application. It should be apparent that the described embodiment is one embodiment of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the application without any inventive step, are within the scope of protection of the application.
It is to be noted that, unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by those of ordinary skill in the art to which this application belongs. If the description refers to "first", "second", etc. throughout this document, these descriptions are only used for distinguishing similar objects, and should not be understood as indicating or implying relative importance, order or implied number of indicated technical features, it should be understood that the data described in "first", "second", etc. may be interchanged where appropriate. If "and/or" is presented throughout, it is meant to include three juxtapositions, exemplified by "A and/or B" and including either scheme A, or scheme B, or schemes in which both A and B are satisfied. Furthermore, spatially relative terms, such as "above," "below," "top," "bottom," and the like, may be used herein for ease of description to describe one element or feature's spatial relationship to another element or feature as illustrated in the figures, and should be understood to encompass different orientations in use or operation in addition to the orientation depicted in the figures.
Fig. 1 shows a schematic diagram of a system for chromatographic analysis of isotopic gas compositions according to one embodiment of the present invention. Referring to fig. 1, the system for analyzing isotope gas composition by chromatography includes: a sample feeding assembly, a pre-separation column 20, a separation column 30, a detector 40 and a switching device 50.
The sample injection assembly is configured to receive a quantity of a sample gas including a sample component and an impurity component. In the present embodiment, the sample component is a hydrogen isotope component or a helium isotope component. Wherein the hydrogen isotope component generally comprises a hydrogen-containing compound containing H 2 、D 2 、T 2 HD, HT, DT, the helium isotope component typically contains He-3 and He-4 with a very small amount of a hydrogen isotope component. Impurity component by containing O 2 、N 2 、CH 4 CO, etc.
The pre-separation column 20 receives the sample gas in the sample assembly carried by the first carrier gas and separates the sample component from the contaminant component in the sample gas. In this embodiment, after the sample gas enters the pre-separation column 20, the pre-separation column 20 can adsorb the impurity components, so that the diffusion rates of the sample components and the impurity components in the pre-separation column are different, the sample components can preferentially flow out of the pre-separation column 20, and then the impurity components flow out of the pre-separation column 20, thereby realizing the separation of the sample components and the impurity components. Illustratively, the pre-separation column 20 may be a normal temperature molecular sieve separation column that can adsorb impurity components at normal temperature, but has no adsorption effect on hydrogen isotope components and helium isotope components.
The separation column 30 is used for receiving the sample components separated by the pre-separation column 20 and separating each isotope component in the sample components. As shown in fig. 1, the separation column 30 is disposed in a liquid nitrogen storage container 31 such that the separation column 30 is maintained in a cryogenic environment of liquid nitrogen, so that the separation column 30 can separate each isotope component in the sample component at the temperature of the liquid nitrogen.
In this embodiment, the separation column 30 may be a low temperature separation column using modified alumina as a filler. Under the low-temperature environment of liquid nitrogen, the adsorption capacity of the separation column 30 to each isotope component is different, so that the diffusion rates of each isotope component in the separation column 30 are different, and each isotope component can flow out of the separation column 30 in sequence, thereby realizing the separation of each isotope component.
In some embodiments, light of the isotopic components is preferentially extracted over heavy components, where the heavy components are the relatively heavier relative molecular mass component of the isotope and the light components are the relatively lighter relative molecular mass component of the isotope. Illustratively, the hydrogen isotopes are each hydrogen isotopes in the order of hydrogen evolution 2 、HD、HT、D 2 DT and T 2 。
A chromatographic detector 40 is connected to the separation column 30 for detecting and analyzing each isotopic component flowing out of the separation column 30. In the present embodiment, each isotope component sequentially flows out of the separation column 30 and enters the chromatographic detector 40, and the chromatographic detector 40 sequentially performs detection analysis on each isotope component to obtain a characteristic peak of each isotope component. According to the characteristic peak of each isotope component, the abundance of each isotope component can be analyzed and determined. The chromatographic Detector 40 may be a Thermal Conductivity Detector (TCD), among others.
The switching device 50 is respectively connected with the sample feeding assembly, the pre-separation column 20 and the separation column 30, the switching device 50 is used for switching connection of gas circuits to control connection and disconnection among the sample feeding assembly, the pre-separation column 20 and the separation column 30, so that the sample gas is controlled to quantitatively enter the pre-separation column 20 in the sample feeding assembly and the gas outflow time in the pre-separation column 20 is controlled, the separated sample components flow out to be conveyed to the separation column 30, and the impurity components are reserved in the pre-separation column 20 to remove the impurity components.
The chromatographic analysis system in the embodiment of the invention adopts the quantitative part to sample, realizes the quantification of the sample gas and reduces the loss of the sample gas. In the embodiment, the pre-separation column is adopted to remove impurity components in the sample gas in advance, so that the service life of the low-temperature separation column is prolonged. And the separation column adopts the modified alumina as the filler, so that the separation of isotope components is realized, the separation effect is improved, the detector can quickly and accurately analyze each isotope component on line, and the precision of a chromatographic analysis system is improved.
In some embodiments, the switching device 50 is configured to have a first operating state and a second operating state. When the switching device 50 is switched to the first working state, the gas path between the sample feeding assembly and the pre-separation column 20 is cut off, and the gas path between the pre-separation column 20 and the separation column 30 is cut off; when the switching device 50 is switched to the second working state, the sample injection assembly is communicated with the pre-separation column 20, and the pre-separation column 20 is communicated with the separation column 30.
In this embodiment, the switching device 50 is controlled to switch to different working states to control the gas path communication state between the sample injection assembly and the pre-separation column 20 and the separation column 30, so as to control the sample gas to be injected into the sample injection assembly for quantification in the first working state, and then switch to the second working state to control the quantitative sample gas to be conveyed to the pre-separation column 20.
As shown in fig. 1, in some embodiments, the chromatography system further includes a secondary carrier gas circuit 62 for providing a secondary carrier gas. The switching means 50 is arranged to switch from the second to the first operating state after the sample components have flowed out of the pre-separation column 20 and all have flowed into the switching means 50. When the switching device 50 is switched to the first operating state, the separation column 30 is communicated with the second carrier gas passage 62 through the switching device 50, so that the second carrier gas is introduced to carry the sample components into the separation column 30 by the second carrier gas.
Further, the chromatography system further comprises a third carrier gas circuit 63 for supplying a third carrier gas. The switching device 50 is configured such that when switching to the first operating state, the pre-separation column 20 is in communication with the third carrier gas passage 63, so that the third carrier gas is introduced to carry the impurity components remaining in the pre-separation column 20 out of the entire system by the third carrier gas passage 63.
In the embodiment, the connection of the gas circuit is switched by arranging the switching device, and the appropriate impurity cutting time is controlled, so that the gas circuit is switched from the second working state to the first working state, the sample component flows into the switching device 50 and the gas circuit between the switching device 50 and the separation column, and the impurity component is retained in the pre-separation column 20, so that the transportation of the sample component to the separation column 30 can be controlled in the first working state, and the impurity component is not allowed to flow to the separation column 30.
In some embodiments, the switching device 50 is provided with a plurality of ports, and the switching of the operating state is realized by controlling the conduction between the ports. Specifically, the switching device 50 may be a ten-way valve that includes ten ports. As shown in fig. 1, the first port 1 is communicated with the third carrier gas path, the second port 2 is communicated with an exhaust line, the third port 3 and the fourth port are both sealed by the sealing member 51, the fifth port 5 is communicated with the quantitative portion 12 of the sample injection assembly, the sixth port 6 and the tenth port 0 are respectively communicated with two ends of the pre-separation column 20, the seventh port 7 is communicated with another exhaust line, the eighth port 8 is communicated with the second carrier gas path, and the ninth port 9 is communicated with the separation column 30.
In the first working state, as shown in fig. 1, the fifth port 5 is connected to the fourth port 4, but not connected to the sixth port 6, so that the sample gas in the sample injection assembly cannot enter the pre-separation column 20, and the quantification of the sample gas in the sample injection assembly is realized.
In addition, in the first working state, the eighth port 8 and the ninth port 9 are communicated with each other, so that the second carrier gas circuit 62 is communicated with the separation column 30, the separation column 30 and the chromatographic detector 40 can be purged and protected by the second carrier gas before the test, the function of the separation column is prevented from being affected by the impurities, and after the pre-separation column 20 separates the sample gas, the second carrier gas is used for carrying the sample components to enter the separation column 30.
In addition, in the first working state, the first port 1 is communicated with the tenth port 0, and the sixth port 6 is communicated with the seventh port 7, so that the third carrier gas path 63 is communicated with the pre-separation column 20, and meanwhile, the pre-separation column 20 is communicated with the evacuation pipeline, so that the pre-separation column 20 can be subjected to purging protection by using the third carrier gas before testing, impurities are prevented from entering and affecting the function of the pre-separation column, and after the pre-separation column 20 separates the sample gas, the third carrier gas is used for carrying the impurity components retained in the pre-separation column 20 and discharging the impurity components out of the system.
In a second working state, as shown in fig. 2, the fifth port 5 is conducted with the sixth port 6, the seventh port 7 is conducted with the eighth port 8, the ninth port 9 is conducted with the tenth port 0, and the first port 1 is conducted with the second port, so that the sample injection assembly is communicated with the pre-separation column 20, and thus the quantitative sample gas in the sample injection assembly is controlled to be carried into the pre-separation column 20 by using the first carrier gas for impurity removal. The sample component separated by the pre-separation column 20 flows into the switching device 50 and the gas circuit therebehind from the tenth port 0, and then the switching device is switched to the first working state by selecting proper impurity cutting time, so that the impurity component is retained in the pre-separation column 20 and does not flow into the switching device 50 from the tenth port 0, and the separation of the impurity component is realized.
The embodiment is provided with the switching device, so that the connection mode of the gas pipeline in the chromatographic analysis system is changed, the switching of the chromatographic analysis system between two working states is realized, the circulation of gas among all devices is convenient to control, and the arrangement and the connection of the gas pipeline are simplified.
In some embodiments, the sample injection assembly comprises: sample inlet 11, ration portion 12 and first carrier gas circuit 61. Referring to fig. 1, the quantitative section 12 is connected to the sample inlet 11 for receiving the sample gas flowing from the sample inlet 11. The first carrier gas path 61 is connected to an inlet of the quantitative part 12, an outlet of the quantitative part 12 is connected to the switching device 50, and the first carrier gas path 61 is used for providing a first carrier gas to carry the sample gas in the quantitative part 12 to sequentially enter the switching device 50 and the pre-separation column 20. Specifically, the outlet of the dosing section 12 communicates with the fifth port 5 of the switching device 50. The quantitative section 12 may be a quantitative ring of 10. Mu.l.
In some embodiments, a carrier gas interface 612 is disposed on a gas path between the quantitative portion 12 and the sample inlet 11, and the first carrier gas path 61 is connected to the quantitative portion 12 through the carrier gas interface 612. The carrier gas interface 612 may be configured to control on/off of the first carrier gas, and the carrier gas interface 612 is illustratively a valve. In addition, a carrier gas switching valve 611 is further disposed on the first carrier gas path 61, and is used for controlling the opening and closing of the first carrier gas.
Referring to fig. 1 and 2, a penetration member 14 is disposed between the sample inlet 11 and the quantitative section 12, and is configured to control a sample introduction flow rate of the sample gas. In some embodiments, the permeation element 14 is a leak hole, which can control the sample gas micro-injection, so that the pressure application range of the chromatographic analysis system is wider, and the sample gas with different injection pressures can be detected and analyzed.
A control valve 13 is provided between the permeable member 14 and the quantitative section 12, and the control valve 13 is provided to control the sample introduction time of the sample gas, thereby controlling the sample introduction amount of the sample gas. Wherein the control valve 13 may be a solenoid valve.
In addition, a sample injection valve 111 is further disposed between the sample injection port 11 and the permeation element 14, so as to control the sample injection of the sample gas. The injection valve 111 is further connected to a pressure sensor 15 for monitoring the injection pressure of the sample gas, so as to facilitate the subsequent analysis of the content of each isotope component in the sample gas.
As shown in fig. 1, the chromatography system further comprises a suction line 71 and a vacuum pump 70. Wherein, one end of the air extraction pipeline 71 is connected between the control valve 13 and the quantitative part 12, the other end is connected with the vacuum pump 70, the vacuum pump 70 is used for carrying out air extraction and cleaning on the quantitative part 12 before sample injection, so as to remove impurities in the quantitative part 12 and the gas pipeline and the residual sample of the last detection and analysis, and avoid the influence on the analysis result.
In some embodiments, a vacuum port 73 is provided on the gas path between the control valve 13 and the carrier gas port 612, the suction line 71 is connected to the vacuum port 73, and the vacuum port 73 can control the on/off of the suction line 71. Illustratively, the vacuum port 73 may be a valve. In addition, a vacuum switch valve 72 is provided on the suction line 71 for controlling the on/off of the vacuum pump 70.
As shown in fig. 1, the chromatography system further includes a fourth carrier gas circuit 64. A fourth carrier gas circuit 64 is connected to the chromatography detector 40 for providing a fourth carrier gas to the chromatography detector 40 as a reference gas.
In a preferred embodiment, the chromatography system further comprises a carrier gas control device 60. The carrier gas control device 60 includes a carrier gas inlet, a plurality of carrier gas outlets, and a flow rate control member (not shown in the drawings). The carrier gas inlet is used for being connected with the carrier gas storage container to receive the carrier gas. The carrier gas outlets are respectively connected to the first carrier gas path 61, the second carrier gas path 62, the third carrier gas path 63, and the fourth carrier gas path 64, so as to provide carrier gas to the first carrier gas path 61, the second carrier gas path 62, the third carrier gas path 63, and the fourth carrier gas path 64. The flow rate control part is arranged between each carrier gas outlet and the carrier gas inlet and is used for controlling the flow rate of the carrier gas flowing out of each carrier gas outlet so as to provide carrier gases with different flow rates for different carrier gas circuits.
Specifically, the flow rate control member may be an air resistor capable of adjusting the flow rate of the incoming carrier gas and outputting the same to each carrier gas circuit. And compressed gas can be provided for the first carrier gas circuit as the first carrier gas through the adjustment of the first flow rate control part. In addition, a suitable pressure of the second carrier gas may be selected, and the carrier gas is adjusted to a suitable pressure by the second flow rate control member and then output to the second carrier gas path, so as to provide the carrier gas with a suitable pressure for the separation column 30 to separate the isotope components.
In this embodiment, the carrier gas may be neon, which may provide protection for the pre-separation column as well as the separation column, yet does not affect the detection and analysis of the isotopic composition by the chromatographic detector 40.
The embodiment of the invention also provides a chromatographic analysis method of the isotope gas components. The chromatographic analysis method in this embodiment can be implemented by using the chromatographic analysis system of the isotopic gas component in the above embodiment.
The chromatographic analysis method in the present example specifically includes the following steps.
And 2, conveying the sample components flowing out of the pre-separation column 20 to a separation column 30, and separating the sample components by the separation column 30 to obtain the isotope components.
And 3, conveying each separated isotope component to a detector, and detecting by the detector to obtain a characteristic peak of each isotope component.
And 4, determining the abundance of each isotope component in the sample gas according to the intensity of each characteristic peak.
Specifically, in step 1, at the start of the test, the switching device 50 is switched to the first operating state, and the gas path between the quantifying unit 12 and the pre-separation column 20 is cut off. In some embodiments, the switching device 50 is in the first operating state when the chromatography system is in the standby state, and the sample injection can be started without switching the operating state. Then, the sample gas is introduced into the quantitative section 12 to quantify the sample gas. Then, the switching device 50 is switched to the second operation state, the quantitative section 12 is switched to be communicated with the pre-separation column 20, and the sample gas in the quantitative section 12 is transported to the pre-separation column 20 by the first carrier gas.
When the sample is injected into the quantitative portion 12, the sample injection flow rate and the sample injection time of the sample gas can be controlled to control the sample injection amount of the sample gas in the quantitative portion 12, thereby realizing the quantitative determination of the sample gas.
In step 1, after the sample component completely flows out from the pre-separation column 20, the switching device 50 is switched to the first working state to disconnect the pre-separation column 20 and the separation column 30, so as to prevent the impurity component from flowing into the separation column 30. Then, step 2 is performed, the sample component is carried by the second carrier gas to enter the separation column 30 and the chromatographic detector 40 in sequence, and the impurity component in the pre-separation column 20 is carried by the third carrier gas to flow out.
Specifically, when the pre-separation column 20 separates the sample gas, the sample component flows out of the pre-separation column 20 preferentially to the impurity component due to the difference in diffusion rates of the sample component and the impurity component in the pre-separation column 20, and the flowing sample component may enter the switching device 50 from the tenth port 0 and flow out to the separation column 30 from the ninth port 9. Therefore, the switching device 50 is switched from the second operation state to the first operation state by controlling an appropriate cut-off time so that the sample component entirely flows into the switching device 50 without allowing the impurity component to flow into the switching device 50 from the tenth port 0. Furthermore, the third carrier gas may be used to reversely blow out the impurity components in the gas path and the pre-separation column 20 out of the whole system, and simultaneously, the second carrier gas is used to carry all the pure sample components in the switching device 50 and the gas path to the separation column 30 for separation, and then the second carrier gas carries each separated isotope component to the chromatographic detector 40 in sequence for detection and analysis.
In the preferred embodiment, before measuring the sample gas, the quantitative portion 12, the pre-separation column 20, the separation column 30 and the chromatographic detector 40 are purged and cleaned by using the carrier gas to purge and protect them, so as to prevent the entrance of the impurity gas from affecting the detection and analysis.
Before the test, the chromatographic analysis system is in a standby state, and purging and cleaning are carried out by using a carrier gas (for example, high-purity neon), and the switching device is in a first working state, namely, a gas path among the quantifying part 12, the pre-separation column 20 and the separation column 30 is cut off. The quantitative section 12 is then purged with the first carrier gas, while the pre-separation column 20 is purged with the second carrier gas, and the separation column 30 and the chromatography detector 40 are purged with the third carrier gas, to purge and protect these devices, respectively.
In addition, when the chromatographic analysis system is in a standby state, that is, when the switching device 50 is in the first operating state, the carrier gas can be continuously used to purge and protect the pre-separation column 20 and the separation column 30, so as to prevent the entry of impurity gas from affecting the functions of the pre-separation column and the separation column.
During test and analysis, the quantitative part 12 can be firstly purged and cleaned, the first carrier gas is conveyed into the quantitative part 12, and meanwhile, the quantitative part 12 is vacuumized by the vacuum pump 70 and continuously circulated for a period of time, so that impurities and samples remained in the quantitative part 12 in the last test are carried out, and the influence of the impurities and the samples on the detection and analysis of the sample gas at this time is avoided.
In step 4, the standard isotope gas mixture may be used to calibrate the chromatographic characteristic peak height or the linear relationship between the peak area and the sample injection amount (or the partial pressure of sample injection) of each isotope component in advance. When the abundance of each isotope component in the sample gas is analyzed, the sample injection amount (or the sample injection pressure) of each isotope component in the sample gas is determined according to the chromatographic characteristic peak height or peak area of each isotope component in the sample gas and the calibrated linear relation.
Further, determining the abundance of each isotope component according to the sample introduction amount of each isotope component and the total sample introduction amount of the sample gas; or determining the abundance of each isotope component according to the partial injection pressure of each isotope component and the total injection pressure of the sample gas, thereby realizing the on-line analysis of the abundance of each isotope component in the sample gas and improving the analysis precision.
The chromatographic analysis method of the present invention is further illustrated below by specific examples.
Example 1: calibration and on-line analysis of hydrogen isotope composition
When the system is in a standby state, the switching device 50 is in a first working state, and the pre-separation column 20 and the low-temperature separation column 30 are purged and protected by the high-purity Ne gas, so that the function of the columns is prevented from being influenced by the entry of miscellaneous gas.
During analysis, when the switching device is in the first working state, the gas pipeline behind the injection valve 111 and the quantitative part 12 are purged and cleaned by the cooperation of the first carrier gas (namely, ne compressed gas) and the vacuum pump. Then, the sample gas is injected into the quantitative section 12 through the micro leak hole, and the injection time can be controlled by the control valve 13. After the sample introduction is finished, the switching device 50 is switched to the second working state, the gas in the quantitative part 12 enters the pre-separation column 20 at normal temperature, the proper impurity cutting time is selected, and the first working state is switched to enable the gas to be separatedO of (A) to (B) 2 、N 2 And removing impurity gases. Then, the impurity gas in the pre-separation column 20 at normal temperature is blown out of the pre-separation column 20 in a reverse direction by the third carrier gas, the second carrier gas sends the pure hydrogen isotope gas to the low-temperature separation column 30 to complete the hydrogen isotope separation, and the characteristic peaks of the components are detected by the TCD.
The characteristic peak height and the sample injection amount (or partial pressure) of the corresponding component have a linear relation, and a corresponding linear calibration formula P is obtained through calibration Is divided into = aA + b, where a is slope, b is intercept, and a is peak height. Wherein D is shown in FIGS. 3 to 7 2 、H 2 HT, DT and T 2 The standard condition partial pressure and the peak height are linearly fitted. And then combining the test temperature T and the total injection pressure P to calculate the corresponding component concentration of C = (aA + b)/(P x 273/(T + 273)).
In this embodiment, the linear calibration formulas of the components are respectively:
according to the calibration result, the on-line analysis of the content of the six components of the hydrogen isotope can be realized, and the precision can be controlled to be 0.01 percent. Fig. 8 shows the results of analysis of the contents of the components in one hydrogen isotope sample gas using the above calibration results.
Example 2: calibration and on-line analysis of helium isotope composition
He-3 mixed gases with different concentrations are obtained through gas distribution, the He-3 mixed gases with different concentrations are respectively injected into a chromatographic analysis system for analysis by adopting the same method and steps as those in the embodiment 1, the characteristic peak of the He-3 component is detected through TCD, and a linear relation curve of the characteristic peak area and the injection amount (or partial pressure) of the corresponding component is obtained through fitting calculation, as shown in figure 9. Wherein, the peak area A of the characteristic peak is proportional to the sample amount of He-3, namely:
A＝γ·n·C (1)
in the formula, n is total sample amount, C is abundance of He-3, and gamma is a proportionality coefficient. The total sample count n can be expressed as:
wherein δ is a scaling factor with dimension. Combining equations (1) and (2), one can obtain:
thus, the corrected formula for the abundance of He-3 is:
wherein T is temperature; both alpha and delta are coefficients, which can be calculated from the above-mentioned calibrated linear relationship. Through calculation, the correction formula of the abundance ratio of the He-3 component in the embodiment is as follows:
according to the calibration result, the content of the helium isotope component can be analyzed on line.
It should also be noted that, in the case of the embodiments of the present invention, features of the embodiments and examples may be combined with each other to obtain a new embodiment without conflict.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and the scope of the present invention is subject to the scope of the claims.
Claims (19)
1. A system for chromatographic analysis of isotopic gas compositions, comprising:
a sample introduction assembly configured to receive a quantity of a sample gas, the sample gas including a sample component and an impurity component;
a pre-separation column for receiving the sample gas carried by the first carrier gas in the sample introduction assembly and separating a sample component from an impurity component in the sample gas;
a separation column for receiving the sample components separated by the pre-separation column, the separation column being disposed in a liquid nitrogen storage container, the separation column being configured to separate each isotope component in the sample components at a temperature of the liquid nitrogen;
a chromatographic detector connected to the separation column for detecting the gas component entering it for analysis;
and the switching device is respectively connected with the sample injection assembly, the pre-separation column and the separation column, and is used for switching gas circuit connection so as to control the communication and the cut-off among the sample injection assembly, the pre-separation column and the separation column.
2. The system of claim 1, wherein the switching device is configured to have a first operating state and a second operating state; wherein the content of the first and second substances,
when the switching device is switched to a first working state, the gas circuit between the sample feeding assembly and the pre-separation column is cut off, and the gas circuit between the pre-separation column and the separation column is cut off;
when the switching device is switched to a second working state, the sample feeding assembly is communicated with the pre-separation column, and the pre-separation column is communicated with the separation columns.
3. The system of claim 2, further comprising: the second carrier gas circuit is used for providing a second carrier gas;
the switching device is used for switching to the first working state after the sample component flows out of the pre-separation column and all flows into the switching device;
when the switching device is switched to the first working state, the separation column is communicated with the second carrier gas path through the switching device, so that the sample components are carried by the second carrier gas to enter the separation column.
4. The system of claim 3, further comprising: the third carrier gas circuit is used for providing third carrier gas;
the switching device is configured to: when the first working state is switched, the pre-separation column is communicated with the third gas-carrying gas circuit, so that the impurity components in the pre-separation column carried by the third gas-carrying gas circuit flow out.
5. The system of claim 1, wherein the sample introduction assembly comprises:
a sample inlet is arranged at the bottom of the sample inlet,
the quantitative part is connected with the sample inlet and is used for receiving the sample gas flowing in from the sample inlet;
the first carrier gas circuit is connected with the inlet of the quantitative part, the outlet of the quantitative part is connected with the switching device, and the first carrier gas circuit is used for providing the first carrier gas so as to carry the sample gas in the quantitative part to sequentially enter the switching device and the pre-separation column.
6. The system of claim 5, wherein a permeable member is disposed between the sample inlet and the quantification section, and is configured to control a sample introduction flow rate of the sample gas.
7. The system according to claim 6, wherein a control valve is arranged between the permeation member and the quantitative section, the control valve being arranged to control a sample introduction time of the sample gas.
8. The system of claim 7, further comprising:
an air suction line having one end connected between the control valve and the quantitative part,
the vacuum pump is connected with the other end of the air pumping pipeline and used for pumping air and cleaning the quantitative part before sample injection.
9. The system of claim 1, further comprising: and the fourth carrier gas circuit is connected with the chromatographic detector and is used for providing fourth carrier gas for the chromatographic detector as reference gas.
10. The system of any one of claims 1-9, further comprising a carrier gas control device, the carrier gas control device comprising:
a carrier gas inlet for connection with a carrier gas storage container to receive a carrier gas;
the carrier gas outlets are respectively connected with the first carrier gas circuit, the second carrier gas circuit, the third carrier gas circuit and the fourth carrier gas circuit;
and the flow rate control part is arranged between each carrier gas outlet and the carrier gas inlet and is used for controlling the flow rate of the carrier gas flowing out of each carrier gas outlet.
11. A method for chromatographic analysis of an isotopic gas component, characterized by being carried out using a system for chromatographic analysis of an isotopic gas component according to any one of claims 1 to 10; the method comprises the following steps:
quantitatively feeding a sample gas into a pre-separation column, wherein the pre-separation column separates and separates sample components and impurity components in the sample gas;
conveying the sample components flowing out of the pre-separation column into a separation column, and separating the sample components by the separation column to obtain isotope components;
conveying each separated isotope component to a detector, and detecting by the detector to obtain a characteristic peak of each isotope component;
determining the abundance of each isotopic component in the sample gas based on the intensity of each characteristic peak.
12. The method of claim 11, further comprising:
switching the switching device to a first working state to cut off the gas path between the quantitative part and the pre-separation column;
feeding the sample gas into a quantitative section to quantify the sample gas;
switching the switching device to a second working state to switch the quantitative part to be communicated with the pre-separation column;
transporting the sample gas in the quantifying portion into the pre-separation column.
13. The method according to claim 12, wherein a sample flow rate and a sample timing of the sample gas are controlled to control a sample amount of the sample gas in the quantitative section when the sample is introduced into the quantitative section.
14. The method of claim 12, wherein the switching device is switched to a first operating state after the sample component has completely flowed from the pre-separation column;
the second carrier gas carries the sample components to sequentially enter the separation column and the chromatographic detector;
and the third carrier gas carries the impurity components in the pre-separation column to flow out.
15. The method of claim 11, further comprising: the quantitative section, pre-separation column, separation column and chromatography detector are purged with a carrier gas prior to measuring the sample gas.
16. The method according to claim 15, wherein a gas path between the quantitative section, the pre-separation column and the separation column is cut off,
purging the quantitative section with a first carrier gas;
simultaneously, the pre-separation column is purged with a second carrier gas, and the separation column and the chromatographic detector are purged with a third carrier gas.
17. The method according to claim 15, wherein the purge cleaning of the quantitative section is performed by evacuating the quantitative section by a vacuum pump while feeding a first carrier gas into the quantitative section.
18. The method of claim 11, further comprising:
calibrating the chromatographic characteristic peak height or the linear relation between the peak area and the sample injection amount of each isotope component in advance by using standard isotope mixed gas;
and determining the sample injection amount of each isotope component in the sample gas according to the chromatographic characteristic peak height or peak area of each isotope component in the sample gas and the calibrated linear relation.
19. The method of claim 18, further comprising:
and determining the abundance of each isotope component according to the sample introduction amount of each isotope component and the total sample introduction amount of the sample gas.
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