CN115808480A - Method for detecting methane and non-methane total hydrocarbons in gas - Google Patents
Method for detecting methane and non-methane total hydrocarbons in gas Download PDFInfo
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 422
- 229930195733 hydrocarbon Natural products 0.000 title claims abstract description 87
- 150000002430 hydrocarbons Chemical class 0.000 title claims abstract description 87
- 238000000034 method Methods 0.000 title claims abstract description 58
- 238000004458 analytical method Methods 0.000 claims abstract description 90
- 238000010828 elution Methods 0.000 claims abstract description 64
- 238000005070 sampling Methods 0.000 claims abstract description 36
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 claims abstract description 28
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000000945 filler Substances 0.000 claims abstract description 20
- 206010057175 Mass conditions Diseases 0.000 claims abstract description 12
- 239000007789 gas Substances 0.000 claims description 33
- 239000012159 carrier gas Substances 0.000 claims description 23
- 238000012856 packing Methods 0.000 claims description 21
- 238000004445 quantitative analysis Methods 0.000 claims description 19
- 238000010438 heat treatment Methods 0.000 claims description 13
- 239000000463 material Substances 0.000 claims description 6
- 238000005259 measurement Methods 0.000 abstract description 15
- 238000001514 detection method Methods 0.000 abstract description 11
- 229910052799 carbon Inorganic materials 0.000 abstract description 7
- 238000000926 separation method Methods 0.000 abstract description 7
- 238000003795 desorption Methods 0.000 abstract description 6
- 239000004215 Carbon black (E152) Substances 0.000 description 11
- 239000000243 solution Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 4
- 239000012080 ambient air Substances 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 102100037114 Elongin-C Human genes 0.000 description 2
- 101001011859 Homo sapiens Elongin-A Proteins 0.000 description 2
- 101001011846 Homo sapiens Elongin-B Proteins 0.000 description 2
- 101000881731 Homo sapiens Elongin-C Proteins 0.000 description 2
- 101000836005 Homo sapiens S-phase kinase-associated protein 1 Proteins 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000010926 purge Methods 0.000 description 2
- 150000001335 aliphatic alkanes Chemical class 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000012855 volatile organic compound Substances 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02C20/00—Capture or disposal of greenhouse gases
- Y02C20/20—Capture or disposal of greenhouse gases of methane
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Abstract
The invention provides a method for detecting methane and non-methane total hydrocarbons in gas, and relates to the technical field of gas component detection and analysis. The detection method comprises the steps of firstly, enriching a sample gas to be detected by using an enrichment pipe, then sequentially carrying out first analysis and second analysis, respectively analyzing and separating methane and non-methane total hydrocarbons from the enrichment pipe, and then respectively detecting to obtain the contents of the methane and the non-methane total hydrocarbons; and the elution volume of the first analysis is larger than the elution volume of methane under the same analysis temperature and filler mass condition, and is smaller than the elution volume of ethane under the same analysis temperature and filler mass condition. According to the method, the measurement of the methane and the non-methane total hydrocarbons can be realized by one sampling circulation under the condition that only one enrichment pipe is adopted through a secondary desorption mode, and compared with the existing method for measuring the methane and the non-methane total hydrocarbons by utilizing a PQ column and a methane quantitative ring, the loss of low carbon such as ethane in the separation process is effectively avoided.
Description
Technical Field
The invention relates to the technical field of gas component detection and analysis, in particular to a method for detecting methane and non-methane total hydrocarbons in gas.
Background
The methane gas is one of gases contributing to the greenhouse effect of the atmosphere, and the NMHC is a generic term for all hydrocarbons except methane, and mainly comprises components such as alkane, alkene, aromatic hydrocarbon and oxygenated hydrocarbon. The non-methane total hydrocarbons can simply and visually represent the pollution state of the VOCs to a certain extent.
At present, two main scenes, namely a fixed pollution source and ambient air, are mainly used for detecting methane and non-methane total hydrocarbons. For monitoring the emission of non-methane total hydrocarbons in a fixed pollution source and ambient air, a gas chromatography-hydrogen flame ionization detector is mainly used for detection and analysis. The main detection methods at present comprise an indirect method and a direct method.
An indirect method: the contents of total hydrocarbon and methane (calculated by carbon) are respectively measured by two chromatographic columns, and the difference between the contents is the content of non-methane total hydrocarbon (indirect method). The direct method comprises the following steps: separating methane from total hydrocarbon by means of chromatographic column separation, valve switching, back flushing and other measures to make non-methane total hydrocarbon produce peak separately and directly measure concentration. At present, the detection of waste gas of a fixed pollution source is mainly based on an indirect method, and the monitoring of ambient air is mainly based on a direct method.
However, in the existing process for determining non-methane total hydrocarbons by using a direct method, due to the problem of the filler property of the enrichment pipe, methane can be retained to a certain extent, and the measurement deviation of the non-methane total hydrocarbons can be caused by the part of methane. A pre-column is often required to be added behind the enrichment pipe, and methane and non-methane total hydrocarbons are separated in a gradient heating mode, so that the analysis period is prolonged, and rapid analysis cannot be realized. And the requirements on the instrument are high.
In addition, because of the methane retention effect of the enrichment pipe, the enrichment pipe cannot be connected with a methane quantitative loop in series for methane quantitative analysis. Usually, a separate methane quantitative ring and a PQ column are required to be introduced to realize the measurement of methane, two times of sample injection is required, the flow path is complicated, and the analysis period is long.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a method for detecting methane and non-methane total hydrocarbons in gas, which can realize the measurement of the methane and the non-methane total hydrocarbons by one sampling circulation in a secondary desorption mode under the condition of only adopting one enrichment pipe. Compared with the existing method for measuring the total hydrocarbons of methane and non-methane by utilizing a PQ column and a methane quantitative ring, the method has the advantages that the analysis flow path is simpler, the loss of low carbon such as ethane and the like in the separation process is effectively avoided, and the measurement result is more accurate.
The invention provides a method for detecting methane and non-methane total hydrocarbons in gas, which comprises the following steps:
enriching a sample gas to be detected by using an enrichment pipe, sequentially carrying out first analysis and second analysis, respectively analyzing and separating methane and non-methane total hydrocarbons from the enrichment pipe, and then respectively detecting to obtain the contents of the methane and the non-methane total hydrocarbons;
and the elution volume of the first analysis is larger than the elution volume of methane under the same analysis temperature and packing mass condition, and is smaller than the elution volume of ethane under the same analysis temperature and packing mass condition.
Further, the elution volume curve of methane is as follows:
Q1＝(-0.01068+0.15092×0.98002 T ) X m, wherein: q1 is the elution volume L of methane, T is the elution temperature, and m is the mass g of the filler.
Further, the elution volume curve of ethane is:
Q2＝(0.06362+1.92566×0.97546 T ) X m, wherein: q2 is the elution volume L of ethane, T is the elution temperature, and m is the mass g of the packing.
Further, the packing material of the enrichment pipe is Carbosieve SIVE SIII.
Furthermore, the temperature of the enrichment pipe for enriching the sample gas to be detected is-10 ℃ to 40 ℃.
Further, the temperature of the first analysis is 0-60 ℃;
further, the temperature of the second analysis is 150-300 ℃;
further, the detection is that a flame ionization detector is used for carrying out quantitative analysis on the total hydrocarbons of the methane or the non-methane which are swept out.
Further, the detection method comprises the following steps:
(a) Introducing sample gas to be detected into the enrichment tube for sampling, wherein the temperature of the enrichment tube in the sampling process is-10-40 ℃;
(b) Heating the enrichment pipe after sampling to 0-60 ℃ for first analysis, separating methane from the enrichment pipe under the action of carrier gas, then feeding the methane to a flame ionization detector for quantitative analysis of the swept methane, and measuring to obtain the methane content;
the elution volume of the first analysis is larger than the elution volume of methane under the conditions of the temperature and the mass of the packing of the first analysis and is smaller than the elution volume of ethane under the conditions of the temperature and the mass of the packing of the first analysis;
(c) Heating the enrichment pipe subjected to the first analysis to 150-300 ℃ for second analysis, separating non-methane total hydrocarbons from the enrichment pipe under the action of carrier gas, then feeding the enrichment pipe into a flame ionization detector for carrying out quantitative analysis on the scavenged methane, and measuring to obtain the content of the non-methane total hydrocarbons.
Furthermore, after the first analysis in the step (c), the temperature rise rate for raising the temperature of the enrichment tube before the second analysis is 10-70 ℃/s.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a method for detecting methane and non-methane total hydrocarbons in gas, which comprises the steps of firstly enriching a sample gas to be detected by using an enrichment pipe, then sequentially carrying out primary analysis and secondary analysis, respectively analyzing and separating methane and non-methane total hydrocarbons from the enrichment pipe, and then respectively detecting to obtain the contents of methane and non-methane total hydrocarbons; and the elution volume of the first analysis is larger than the elution volume of methane under the same analysis temperature and packing mass condition, and is smaller than the elution volume of ethane under the same analysis temperature and packing mass condition. According to the method, the measurement of methane and non-methane total hydrocarbons can be realized by one sampling cycle in a secondary desorption mode under the condition that only one enrichment pipe is adopted. Compared with the existing method for measuring the total hydrocarbons of methane and non-methane by utilizing a PQ column and a methane quantitative ring, the method has the advantages that the analysis flow path is simpler, the loss of low carbon such as ethane and the like in the separation process is effectively avoided, and the measurement result is more accurate.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a plot of elution volume of methane on Carbosieve S III as provided by the present invention;
fig. 2 is an elution volume curve of ethane on Carbosieve S iii provided by the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
According to one aspect of the invention, a method for detecting methane and non-methane total hydrocarbons in a gas comprises the steps of:
enriching a sample gas to be detected by using an enrichment pipe, sequentially carrying out primary analysis and secondary analysis, respectively analyzing and separating methane and non-methane total hydrocarbons from the enrichment pipe, and then respectively detecting to obtain the contents of methane and non-methane total hydrocarbons;
the elution volume of the first analysis is larger than the elution volume of methane under the same analysis temperature and filler mass condition, and is smaller than the elution volume of ethane under the same analysis temperature and filler mass condition.
The invention provides a method for detecting methane and non-methane total hydrocarbons in gas, which comprises the steps of firstly enriching a sample gas to be detected by using an enrichment pipe, then sequentially carrying out primary analysis and secondary analysis, respectively analyzing and separating methane and non-methane total hydrocarbons from the enrichment pipe, and then respectively detecting to obtain the contents of methane and non-methane total hydrocarbons; and the elution volume of the first analysis is larger than the elution volume of methane under the same analysis temperature and filler mass condition, and is smaller than the elution volume of ethane under the same analysis temperature and filler mass condition. According to the method, the measurement of methane and non-methane total hydrocarbons can be realized by one sampling cycle in a secondary desorption mode under the condition that only one enrichment pipe is adopted. Compared with the existing method for measuring the total hydrocarbons of methane and non-methane by utilizing a PQ column and a methane quantitative ring, the method has the advantages that the analysis flow path is simpler, the loss of low carbon such as ethane and the like in the separation process is effectively avoided, and the measurement result is more accurate.
The concept of the present application for the analytical separation of methane and non-methane total hydrocarbons from the enrichment pipe is as follows:
1. determination of the elution volume curve for methane:
FIG. 1 is a plot of the elution volume of methane on Carbosieve S III.
Respectively detecting the elution volume of methane at 0 ℃, 20 ℃, 40 ℃, 60 ℃, 80 ℃ and 100 ℃, drawing a fitting curve of the elution volume with respect to temperature according to a reference point, and selecting a fitting model with the minimum residual error, wherein the fitting curve is as follows:
the elution volume curve for methane is: q1= (-0.01068 +0.15092 × 0.98002 T )×m；
Wherein T is temperature and m is the mass g of the filler.
2. Determining the elution volume curve of ethane which is the easiest to elute the non-methane total hydrocarbon component:
figure 2 is an elution volume curve of ethane on Carbosieve S iii.
The elution volume curve for ethane is: q2= (0.06362 + 1.92566X 0.97546) T )×m；
Wherein T is the temperature and m is the mass g of the filler.
Thus, as long as it is ensured that the non-methane total hydrocarbon components (ethane) which are most easily eluted are not eluted, it can be considered that no non-methane total hydrocarbons are lost. That is, only the elution volume Q of the enrichment tube needs to be guaranteed: q1 (methane) < Q2 (ethane); and then the elution of methane is completed and the measurement is carried out. And after the methane is measured, carrying out secondary temperature rise desorption on the enrichment pipe, and measuring the non-methane total hydrocarbon.
In a preferred embodiment of the invention, the packing of the enrichment tube is Carbosieve sciii.
It should be noted that the fillers adopted by the existing non-methane total hydrocarbon enrichment pipe are Tenax GR and Carbosieve SIII type double-filler enrichment pipes, wherein the Carbosieve III type fillers are mainly used for adsorbing low-carbon components and have a certain retention effect on methane. Based on the point, the application designs a new application mode.
In a preferred embodiment of the present invention, the temperature of the enrichment tube for enriching the sample gas to be measured is-10 ℃ to 40 ℃.
As a preferred embodiment, in the sampling mode, the enrichment pipe is kept in a low-temperature state (-10-40 ℃), the sample gas gradually enters the enrichment pipe, and non-methane total hydrocarbons and partial methane in the sample gas are reserved on the enrichment pipe.
In a preferred embodiment of the present invention, the temperature of the first analysis is 0 to 60 ℃;
as a preferred embodiment, the enrichment pipe has a strong retention effect on non-methane total hydrocarbons at the temperature (0-60 ℃) of the first resolution, and the methane can be completely purged at the temperature and the purge volume by controlling the size of the purge volume without loss of the non-methane total hydrocarbons.
In a preferred embodiment of the present invention, the temperature of the second analysis is 150 to 300 ℃;
as a preferable embodiment, under the temperature of the second analysis (150-300 ℃), the residual non-methane total hydrocarbons in the enrichment tube enter a detector for quantitative analysis under the action of a carrier gas, and the measurement of methane and non-methane total hydrocarbons by one-time sampling is realized.
In a preferred embodiment of the invention, the detection is a quantitative analysis of the swept-out methane or non-methane total hydrocarbons using a flame ionization detector.
In a preferred embodiment of the present invention, the detection method comprises the steps of:
(a) Introducing sample gas to be detected into the enrichment tube for sampling, wherein the temperature of the enrichment tube in the sampling process is-10-40 ℃;
(b) Heating the enrichment pipe after sampling to 0-60 ℃ for first analysis, separating methane from the enrichment pipe under the action of carrier gas, then feeding the methane to a flame ionization detector for quantitative analysis of the swept methane, and measuring to obtain the methane content;
the elution volume of the first analysis is larger than the elution volume of methane under the conditions of the temperature and the mass of the packing material of the first analysis and is smaller than the elution volume of ethane under the conditions of the temperature and the mass of the packing material of the first analysis;
(c) Heating the enrichment pipe subjected to the first analysis to 150-300 ℃ for second analysis, separating non-methane total hydrocarbons from the enrichment pipe under the action of carrier gas, then feeding the separated non-methane total hydrocarbons into a flame ionization detector for quantitative analysis of the scavenged methane, and measuring to obtain the content of the non-methane total hydrocarbons.
In the preferred embodiment, the rate of temperature increase in the enrichment tube after the first analysis and before the second analysis in the step (c) is 10 to 70 ℃/s.
In a preferred embodiment, the higher the temperature rise rate of the second analysis, the better the FID detector shows a peak-to-peak shape, and the too low temperature rise rate causes a peak-to-peak tailing. The heating rate is within 10-70 ℃/s, the heating rate is more than 10 ℃/s, and the peak type can meet the detection requirement.
The technical solution of the present invention will be further described with reference to the following examples.
Example 1
A method for detecting methane and non-methane total hydrocarbons, the method comprising the steps of:
(a) Introducing sample gas to be detected into an enrichment tube for sampling, wherein the temperature of the enrichment tube is-10 ℃, the sampling flow is 20ml/min, and the sampling volume is 50ml in the sampling process;
the filler of the enrichment pipe is Carbosieve III, and the mass is 0.05g;
(b) After sampling is finished, the enrichment tube is connected to a carrier gas path, the flow rate of the carrier gas is 20ml/min, the enrichment tube is synchronously heated to the first analysis temperature of 0 ℃, methane in the enrichment tube is desorbed from the enrichment tube under the action of the carrier gas, then the methane is injected into a flame ionization detector to carry out quantitative analysis on the scavenged methane, and the content of the methane is measured;
the elution volume of the first analysis is larger than the elution volume of methane under the conditions of the temperature and the mass of the packing of the first analysis and is smaller than the elution volume of ethane under the conditions of the temperature and the mass of the packing of the first analysis;
(c) And heating the enrichment pipe subjected to the first analysis to 150 ℃ for second analysis, separating non-methane total hydrocarbons from the enrichment pipe under the action of carrier gas, then feeding the separated non-methane total hydrocarbons into a flame ionization detector for carrying out quantitative analysis on the scavenged methane, and measuring to obtain the content of the non-methane total hydrocarbons.
Example 2
A method for detecting methane and non-methane total hydrocarbons, the method comprising the steps of:
(a) Introducing sample gas to be detected into an enrichment tube for sampling, wherein the temperature of the enrichment tube is 40 ℃, the sampling flow is 20ml/min, and the sampling volume is 50ml in the sampling process;
the filler of the enrichment pipe is Carbosieve III, and the mass is 0.05g;
(b) After sampling is finished, the enrichment tube is connected to a carrier gas path, the carrier gas flow rate is 20ml/min, the enrichment tube is synchronously heated to the first analysis temperature of 60 ℃, methane in the enrichment tube is desorbed from the enrichment tube under the action of the carrier gas, and then the methane is injected into a flame ionization detector to carry out quantitative analysis on the scavenged methane, and the methane content is obtained through measurement;
the elution volume of the first analysis is larger than the elution volume of methane under the conditions of the temperature and the mass of the packing of the first analysis and is smaller than the elution volume of ethane under the conditions of the temperature and the mass of the packing of the first analysis;
(c) Heating the enrichment tube after the first analysis to 300 ℃ for second analysis, separating non-methane total hydrocarbon from the enrichment tube under the action of carrier gas, then feeding the enrichment tube into a flame ionization detector for carrying out quantitative analysis on the swept methane, and measuring to obtain the content of the non-methane total hydrocarbon.
Example 3
A method for detecting methane and non-methane total hydrocarbons, the method comprising the steps of:
(a) Introducing sample gas to be detected into an enrichment tube for sampling, wherein the temperature of the enrichment tube in the sampling process is-20 ℃, the sampling flow is 20ml/min, and the sampling volume is 50ml;
the filler of the enrichment pipe is Carbosieve S III, and the mass is 0.03g;
(b) After sampling is finished, the enrichment tube is connected to a carrier gas circuit, the flow rate of the carrier gas is 20ml/min, the enrichment tube is synchronously heated to the first analysis temperature of 20 ℃, the elution volume is 20ml, methane in the enrichment tube is desorbed from the enrichment tube under the action of the carrier gas, then the methane is injected into a flame ionization detector to carry out quantitative analysis on the scavenged methane, and the methane content is obtained through measurement;
note: the elution volume of methane at this time was: q1=2.7ml and the elution volume of ethane Q2=37ml, therefore, the purpose of eluting and separating methane and non-methane total hydrocarbons can be realized by determining the elution volume within 2.7-37 ml.
(c) And heating the enrichment pipe subjected to the first analysis to 160 ℃ for second analysis, separating non-methane total hydrocarbons from the enrichment pipe under the action of carrier gas, then feeding the separated non-methane total hydrocarbons into a flame ionization detector for carrying out quantitative analysis on the scavenged methane, and measuring to obtain the content of the non-methane total hydrocarbons.
Example 4
A method for detecting methane and non-methane total hydrocarbons, the method comprising the steps of:
(a) Introducing sample gas to be detected into an enrichment tube for sampling, wherein the temperature of the enrichment tube in the sampling process is-20 ℃, the sampling flow is 20ml/min, and the sampling volume is 50ml;
the filler of the enrichment pipe is Carbosieve III, and the mass is 0.05g;
(b) After sampling is finished, the enrichment tube is connected to a carrier gas path, the flow rate of the carrier gas is 20ml/min, the enrichment tube is synchronously heated to the first analysis temperature of 40 ℃, methane in the enrichment tube is desorbed from the enrichment tube under the action of the carrier gas, then the methane is injected into a flame ionization detector to carry out quantitative analysis on the scavenged methane, and the content of the methane is measured;
note: the elution volume of methane at this time was: q1=2.8ml and the elution volume of ethane Q2=39ml, therefore, the purpose of eluting and separating methane and non-methane total hydrocarbons can be realized by determining the elution volume within 2.8-39 ml.
(c) And heating the enrichment pipe subjected to the first analysis to 300 ℃ for second analysis, separating non-methane total hydrocarbons from the enrichment pipe under the action of carrier gas, then feeding the separated non-methane total hydrocarbons into a flame ionization detector for carrying out quantitative analysis on the scavenged methane, and measuring to obtain the content of the non-methane total hydrocarbons.
In summary, according to the method for detecting methane and non-methane total hydrocarbons in gas provided by the invention, by means of secondary desorption, the measurement of methane and non-methane total hydrocarbons can be realized by one sampling cycle under the condition of only adopting one enrichment pipe. Compared with the existing method for measuring the total hydrocarbons of methane and non-methane by utilizing a PQ column and a methane quantitative ring, the method has the advantages that the analysis flow path is simpler, the loss of low carbon such as ethane and the like in the separation process is effectively avoided, and the measurement result is more accurate.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A method for detecting methane and non-methane total hydrocarbons in a gas, the method comprising the steps of:
enriching a sample gas to be detected by using an enrichment pipe, sequentially carrying out first analysis and second analysis, respectively analyzing and separating methane and non-methane total hydrocarbons from the enrichment pipe, and then respectively detecting to obtain the contents of the methane and the non-methane total hydrocarbons;
the elution volume of the first analysis is larger than the elution volume of methane under the same analysis temperature and filler mass condition, and is smaller than the elution volume of ethane under the same analysis temperature and filler mass condition.
2. The method of claim 1, wherein the elution volume curve for methane is:
Q1＝(-0.01068+0.15092×0.98002 T ) X m, formulaThe method comprises the following steps: q1 is the elution volume L of methane, T is the elution temperature, and m is the mass g of the filler.
3. The method of claim 1, wherein the elution volume curve for ethane is:
Q2＝(0.06362+1.92566×0.97546 T ) X m, wherein: q2 is the elution volume L of ethane, T is the elution temperature, and m is the mass g of the packing.
4. The method for detecting methane and non-methane total hydrocarbons in a gas according to claim 1, wherein the packing material of the enrichment tube is a Carbosieve type packing material;
preferably, the packing material of the enrichment tube is Carbosieve sciii.
5. The method for detecting methane and non-methane total hydrocarbons in a gas according to claim 1, wherein the enriching tube enriches the sample gas to be detected at a temperature of-10 ℃ to 40 ℃.
6. The method according to claim 1, wherein the temperature for the first analysis is 0 to 60 ℃.
7. The method according to claim 1, wherein the temperature for the second analysis is 150 to 300 ℃.
8. The method of claim 1, wherein the detecting is a quantitative analysis of the methane or non-methane total hydrocarbons swept out by a flame ionization detector.
9. A method for detecting methane and non-methane total hydrocarbons in a gas according to claim 1, characterized in that it comprises the following steps:
(a) Introducing sample gas to be detected into an enrichment pipe for sampling, wherein the temperature of the enrichment pipe in the sampling process is-10-40 ℃;
(b) Heating the enrichment tube after sampling to 0-60 ℃ for first analysis, separating methane from the enrichment tube under the action of carrier gas, then feeding the methane into a flame ionization detector for quantitative analysis of the swept methane, and measuring to obtain the methane content;
the elution volume of the first analysis is larger than the elution volume of methane under the conditions of the temperature and the mass of the packing of the first analysis and is smaller than the elution volume of ethane under the conditions of the temperature and the mass of the packing of the first analysis;
(c) Heating the enrichment pipe subjected to the first analysis to 150-300 ℃ for second analysis, separating non-methane total hydrocarbons from the enrichment pipe under the action of carrier gas, then feeding the separated non-methane total hydrocarbons into a flame ionization detector for quantitative analysis of the scavenged methane, and measuring to obtain the content of the non-methane total hydrocarbons.
10. The method of claim 9, wherein the temperature increase rate for increasing the temperature of the enrichment tube after the first analysis and before the second analysis in step (c) is 10-70 ℃/s.
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