Device and method for analyzing total hydrocarbon and subitem hydrocarbon in oxygen

Abstract

The invention discloses an analysis device and an analysis method for total hydrocarbons and subitem hydrocarbons in oxygen. The analysis device comprises a first ten-way valve with ports a-j, a second ten-way valve with ports A-J, a first quantitative tube, a second quantitative tube, a first chromatographic column, a second chromatographic column, a third chromatographic column, a fourth chromatographic column and an FID (Flame Ionization Detector). According to the analysis device and the analysis method for the total hydrocarbon and the subitem hydrocarbon in the oxygen, samples can be simultaneously added into the two quantitative pipes through the same gas path, and the sample adding efficiency is improved. The arrangement of double valves and four columns can simultaneously analyze total hydrocarbons and subitem hydrocarbons, and the operation is simple and easy. Besides, before analysis, oxygen is separated and discharged out of a gas path, so that main peak interference under the oxygen background can be completely removed, the separation effect is good, the peak shape is uniform, and the test requirement is met.

Description

Technical Field

[0001] This invention belongs to the field of analytical testing technology, specifically relating to an analytical apparatus and method for analyzing total hydrocarbons and specific hydrocarbons in oxygen. Background Technology

[0002] Oxygen produced through air separation processes typically has a purity of over 99.5%. Due to its high oxidizing power and role as a combustion-supporting gas, excessively high levels of hydrocarbon impurities in oxygen can pose significant safety risks during the process. For hydrocarbon detection in oxygen, online chromatographic analysis is commonly used in the industry to display impurity values ​​in real time, enabling monitoring of process risks. Current analytical methods using gas chromatography with a FID (Flame Ionization Detector) involve oxygen passing through the column before reaching the detector. The presence of oxygen signals can interfere with peak elution, and oxygen cannot be completely separated from hydrocarbons within the column, causing peak distortion and obscuring of target peaks, leading to inaccurate quantification. Furthermore, the large amount of oxygen entering the FID detector over a long period can affect its sensitivity. Additionally, current analytical methods are complex when simultaneously measuring total hydrocarbons and specific hydrocarbons, and typically only one test or only one type of impurity can be performed, resulting in low efficiency.

[0003] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide an analytical apparatus and method for analyzing total hydrocarbons and individual hydrocarbons in oxygen, which can simultaneously analyze total hydrocarbons and individual hydrocarbons and avoid interference from oxygen.

[0005] To achieve the above objectives, a specific embodiment of the present invention provides an analytical device for total hydrocarbons and specific hydrocarbons in oxygen, which includes a first ten-way valve with port aj, a second ten-way valve with port Aj, a first quantitative tube, a second quantitative tube, a first chromatographic column, a second chromatographic column, a third chromatographic column, a fourth chromatographic column, and an FID detector.

[0006] The b port of the first 10-way valve is connected to the A port of the 20-way valve. The first metering tube is connected to the c and j ports of the first 10-way valve. One end of the first chromatographic column is connected to the i port, and the other end is connected to the f port. One end of the second chromatographic column is connected to the g port, and the other end is connected to the FID detector. The second metering tube is connected to the C and J ports of the 20-way valve. One end of the third chromatographic column is connected to the H port, and the other end is connected to the FID detector. One end of the fourth chromatographic column is connected to the F port, and the other end is connected to the I port.

[0007] The first carrier gas is introduced through port d, the second carrier gas is introduced through port h, the third carrier gas is introduced through port D, the fourth carrier gas is introduced through port G, and the sample gas is introduced through port a.

[0008] The first ten-way valve and the second ten-way valve have OFF and ON states.

[0009] In the OFF state, the first 10-way valve has its port a connected to port j, port c connected to port b, port d connected to port e, port f connected to port g, and port h connected to port i; the second 10-way valve has its port A connected to port J, port C connected to port B, port D connected to port E, port G connected to port F, and port I connected to port H.

[0010] In the ON state, the first ten-way valve has its a port connected to the b port, its d port connected to the c port, its j port connected to the i port, and its f port connected to the e port; the second ten-way valve has its A port connected to the B port, its D port connected to the C port, its J port connected to the I port, its F port connected to the E port, and its G port connected to the H port.

[0011] Another specific embodiment of the present invention provides an analytical method for total hydrocarbons and specific hydrocarbons in oxygen, which uses the above-described analytical apparatus. The analytical method includes the following steps.

[0012] Both the first and second ten-way valves are in the OFF state. The sample gas to be tested is sequentially delivered to the first metering tube through port a and port j, filling the first metering tube. Excess sample gas is sequentially delivered from the first metering tube through port c, port b, port A, and port J to the second metering tube, filling the second metering tube. Excess sample gas is discharged from the second ten-way valve.

[0013] Switch the first ten-way valve to the ON state. The first carrier gas is introduced into the first metering tube through the d and c ports in sequence, and the sample gas in the first metering tube is backflushed. Then, the first carrier gas carries the sample gas into the first chromatographic column through the j and i ports in sequence. The first chromatographic column separates the oxygen in the sample gas and discharges it through the f and e ports in sequence. The residual sample gas remains in the first chromatographic column.

[0014] After the first ten-way valve is in the ON state for time t1, it switches to the OFF state. The second carrier gas is introduced sequentially through the h port and the i port, and the residual sample gas in the first chromatographic column is sent sequentially through the f port and the g port into the second chromatographic column. The second chromatographic column separates the residual sample gas and sends it sequentially to the FID detector by the second carrier gas for hydrocarbon analysis.

[0015] After the first ten-way valve is switched to the ON state for time t2, the second ten-way valve is switched to the ON state. The third carrier gas backflushes the sample gas in the second quantitative tube through the D port and the C port in sequence. The sample gas is sent into the fourth chromatographic column by the third carrier gas through the J port and the I port in sequence. The fourth chromatographic column separates the oxygen in the sample gas and discharges it through the F port and the E port in sequence. The residual sample gas remains in the fourth chromatographic column.

[0016] After the 20th valve is in the ON state for time t3, it switches to the OFF state. The fourth carrier gas is introduced sequentially through the G port and the F port, and the residual sample gas in the fourth chromatographic column is sent sequentially through the I port, the H port and the third chromatographic column to the FID detector for total hydrocarbon analysis.

[0017] In one or more embodiments of the present invention, the t1 time is 0.5 min to 1.0 min.

[0018] In one or more embodiments of the present invention, the t2 time is 4.5 min to 5.5 min; and / or, the t3 time is 4.55 min to 5.55 min and the t3 > t2.

[0019] In one or more embodiments of the present invention, the first chromatographic column is a Q column filled with porous polymer microspheres, the porous polymer microspheres having a pore size of 60-80 mesh, and the first chromatographic column is used to separate oxygen and hydrocarbon substances.

[0020] In one or more embodiments of the present invention, the second chromatographic column is an N-column filled with a porous polymer, wherein the pore size of the porous polymer is 60-80 mesh, and the second chromatographic column is used to separate hydrocarbons such as methane, ethylene, acetylene, ethane, propylene, and propane.

[0021] In one or more embodiments of the present invention, the third chromatographic column is a glass microcolumn filled with silanized glass microspheres, the pore size of the silanized glass microspheres being 60-80 mesh, and the third chromatographic column is used for total hydrocarbon analysis by means of the empty column effect.

[0022] In one or more embodiments of the present invention, the fourth chromatographic column is a Q column filled with porous polymer microspheres, the porous polymer microspheres having a pore size of 60-80 mesh, and the fourth chromatographic column is used to separate oxygen and hydrocarbons.

[0023] In one or more embodiments of the present invention, the capacity of the first metering tube is 0.5 ml; and / or, the capacity of the second metering tube is 0.2 ml.

[0024] In one or more embodiments of the present invention, the first carrier gas, the second carrier gas, the third carrier gas and the fourth carrier gas are ultrapure nitrogen with a purity of 6N or higher.

[0025] In one or more embodiments of the present invention, the first carrier gas, the second carrier gas, the third carrier gas and the fourth carrier gas are respectively delivered to the corresponding ports of the first ten-way valve and the second ten-way valve through the same gas delivery pipeline, and the first carrier gas, the second carrier gas, the third carrier gas and the fourth carrier gas are in a continuous supply state.

[0026] In one or more embodiments of the present invention, the method for analyzing total hydrocarbons and specific hydrocarbons in oxygen further includes:

[0027] The total hydrocarbon content in oxygen is calibrated using a first standard gas, which is a standard gas with oxygen as the background gas and containing 5 ppm of methane.

[0028] The content of each hydrocarbon component in oxygen is calibrated using a second standard gas. The second standard gas uses oxygen as the background gas and is prepared with 1 ppm methane, 1 ppm ethylene, 1 ppm acetylene, 1 ppm propylene, and 1 ppm propane as standard gases.

[0029] In one or more embodiments of the present invention, the sample gas is introduced for 0.2 min to 0.5 min.

[0030] Compared with existing technologies, the analytical apparatus and method for analyzing total hydrocarbons and individual hydrocarbons in oxygen of the present invention can simultaneously operate and add samples to two quantitative tubes in the same gas path, improving the efficiency of sample addition. The dual-valve, four-column setup allows for simultaneous analysis of total hydrocarbons and individual hydrocarbons, and is simple and easy to operate. Furthermore, before analysis, the method separates and discharges oxygen outside the gas path, thereby completely removing interference from the main peak against the oxygen background, resulting in good separation, uniform peak shape, and meeting testing requirements. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram showing the first and second 10-way valves in the OFF state in one embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram showing the first and second 10-way valves in the ON state in one embodiment of the present invention.

[0034] Explanation of key figure labels:

[0035] 1-First ten-way valve, 2-Second ten-way valve, 3-First quantitative tube, 4-Second quantitative tube, 5-First chromatographic column, 6-Second chromatographic column, 7-Third chromatographic column, 8-Fourth chromatographic column, 9-FID detector. Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0037] like Figures 1-2 As shown, an analytical device for total hydrocarbons and specific hydrocarbons in oxygen according to one embodiment of the present invention has a dual-valve, four-column structure. The analytical device includes a first ten-way valve 1 with port A1, a second ten-way valve 2 with port A1, a first quantitative tube 3, a second quantitative tube 4, a first chromatographic column 5, a second chromatographic column 6, a third chromatographic column 7, a fourth chromatographic column 8, and an FID detector 9.

[0038] The b port of the first ten-way valve 1 is connected to the A port of the second ten-way valve 2, thus connecting the two ten-way valves. The first metering tube 3 is connected to the c and j ports of the first ten-way valve 1. One end of the second chromatographic column 6 is connected to the g port, and the other end is connected to the FID detector 9. One end of the first chromatographic column 5 is connected to the i port, and the other end is connected to the f port. The second metering tube 4 is connected to the C and J ports of the second ten-way valve 2. One end of the third chromatographic column 7 is connected to the H port, and the other end is connected to the FID detector 9. One end of the fourth chromatographic column 8 is connected to the 6 port, and the other end is connected to the I port.

[0039] The first carrier gas is introduced through port d; the second carrier gas is introduced through port h. The third carrier gas is introduced through port D, and the fourth carrier gas is introduced through port G. The sample gas is introduced through port a.

[0040] It is understandable that both the first ten-way valve 1 and the second ten-way valve 2 have ten ports, which are a type of multi-way valve. The ports of each ten-way valve can be connected or blocked according to the usage. The control method for connecting or blocking the ports is a conventional technical means in this field, and will not be described in detail here.

[0041] The first ten-way valve 1 and the second ten-way valve 2 have OFF and ON states.

[0042] In the OFF state, the first 10-way valve 1 has its port a connected to port j, port c connected to port b, port d connected to port e, port f connected to port g, and port h connected to port i. The second 10-way valve 2 has its port A connected to port J, port C connected to port B, port D connected to port E, port G connected to port F, and port I connected to port H.

[0043] In the ON state, the first 10-way valve 1 has its port a connected to port b, port d connected to port c, port j connected to port i, and port f connected to port e. The second 10-way valve 2 has its port A connected to port B, port D connected to port C, port J connected to port I, port F connected to port E, and port G connected to port H.

[0044] Another embodiment of the present invention provides a method for analyzing total hydrocarbons and specific hydrocarbons in oxygen, the method comprising steps S1-S5.

[0045] Step S1: With both the first 10-way valve 1 and the second 10-way valve 2 in the OFF state, the sample gas to be tested is sequentially delivered to the first quantitative tube 3 through port a and port j, filling the first quantitative tube 3 completely. Excess sample gas is sequentially delivered from the first quantitative tube 3 through port c and port b, and port A and port J to the second quantitative tube 4, filling the second quantitative tube 4 completely. Excess sample gas is discharged from the second 10-way valve 2.

[0046] Specifically, in step S1, initially, both the first ten-way valve 1 and the second ten-way valve 2 are in the OFF state. When the first ten-way valve 1 is in the OFF state, the connection method of its ports and the movement path of each gas are as follows:

[0047] Port a is connected to port j, and port j is connected to one end of the first quantitative tube 3. Sample gas enters through port a, exits through port j, and enters the first quantitative tube 3, filling the first quantitative tube 3.

[0048] Port c is connected to port b, and the other end of the first quantitative tube 3 is connected to port c. Port b is connected to port A of the 20th valve 2. After the sample gas fills the first quantitative tube 3, it is sequentially introduced into the 20th valve 2 through port c, port b, and port A.

[0049] Port d is connected to port e. The first carrier gas enters from port d and exits from port e. At this time, the first carrier gas only purges the area between ports d and e and has no other function.

[0050] The h port is connected to the i port, and the i port is connected to one end of the first chromatographic column 5.

[0051] Port f is connected to port g, and port f is also connected to the other end of the first chromatographic column 5. Port g is connected to one end of the second chromatographic column 6, and the other end of the second chromatographic column 6 is connected to the FID detector 9. At this time, the second carrier gas is input from port h, and passes sequentially through port i, the first chromatographic column 5, port f, port g, the second chromatographic column 6, and the FID detector. The second carrier gas only purges the aforementioned positions and has no other effect.

[0052] When the 20th valve 2 is in the OFF state, the connection method of each port and the movement path of each gas are as follows:

[0053] Port A is connected to port J, and port J is connected to one end of the second quantitative tube 4. The sample gas enters the second quantitative tube 4 from the first ten-way valve 1 through port A and port J in sequence, filling the second quantitative tube 4.

[0054] Port C is connected to port B, and port C is also connected to the other end of the second quantitative tube 4. After the sample gas fills the second quantitative tube 4, it is discharged from the second quantitative tube 4 sequentially through port C and port B.

[0055] Port D is connected to port E. The third carrier gas enters through port D and exits through port E. At this time, the third carrier gas only purges the area between ports D and E and has no other function.

[0056] Port G is connected to port F, and port F is connected to one end of the fourth chromatographic column 8.

[0057] Port I is connected to Port H, and Port I is also connected to the other end of the fourth chromatographic column 8. Port H is connected to one end of the third chromatographic column 7, and the other end of the third chromatographic column 7 is connected to the FID detector 9. At this time, the fourth carrier gas is input from Port G, and passes sequentially through Port F, the fourth chromatographic column 8, Port I, Port H, the third chromatographic column 7, and the FID detector 9. At this time, the fourth carrier gas only purges the aforementioned positions and has no other effect.

[0058] Therefore, in step S1, the sample gas is sequentially introduced through port a, port j, the first quantitative tube 3, port A, port J, the second quantitative tube 4, port C, and port B, filling the first and second quantitative tubes 3 and 4 completely, and then discharged through port B. The sample gas is introduced for 0.2-0.5 minutes to ensure that the first and second quantitative tubes 3 and 4 are fully filled and that all existing gas in each port is discharged, avoiding interference with subsequent analysis. This piping configuration allows for simultaneous operation and sample addition to both quantitative tubes using the same gas path, improving sample addition efficiency.

[0059] In one embodiment, the first quantitative tube 3 has a capacity of 0.5 ml, and the second quantitative tube 4 has a capacity of 0.2 ml. This configuration ensures that the amount of sample gas is the same for each analysis, reducing errors from repeated experiments.

[0060] Step S2: Switch the first ten-way valve 1 to the ON state. The first carrier gas is introduced into the first quantitative tube 3 through the d and c ports in sequence, and the sample gas in the first quantitative tube 3 is backflushed. Then, the first carrier gas carries the sample gas into the first chromatographic column 5 through the j and i ports in sequence. The first chromatographic column 5 separates the oxygen in the sample gas and discharges it through the f and e ports in sequence. The residual sample gas remains in the first chromatographic column 5.

[0061] Specifically, in step S2, the first chromatographic column 5 is a Q column filled with polymer porous microspheres with a pore size of 60-80 mesh. The first chromatographic column 5 is used to separate oxygen and hydrocarbon substances, so that when the first carrier gas is backflushed, the oxygen in the sample gas can be separated out.

[0062] After the sample gas fills the first quantitative tube 3 and the second quantitative tube 4, switch the first ten-way valve 1 to the OFF state.

[0063] Specifically, in the ON state, the connection method of each port of the tenth-way valve 1 and the movement path of each gas are as follows:

[0064] Port a is connected to port b, and port b is connected to port A of the 20th valve 2; the sample gas enters the 20th valve 2 sequentially from port a, port b and port A.

[0065] Port d is connected to port c. Port c is connected to one end of the first quantitative tube 3, and the other end of the first quantitative tube 3 is connected to port j. Port j is connected to port i. Port i is connected to one end of the first chromatographic column 5, and the other end of the first chromatographic column 5 is connected to port f. Port f is also connected to port e.

[0066] Therefore, after the first ten-way valve 1 is switched to the ON state, the first carrier gas can be introduced from the d port, and sequentially through the c port, the first quantitative tube 3, the j port and the i port to blow the sample gas into the first chromatographic column 5. Then the oxygen in the sample gas is separated in the first chromatographic column 5, and then the first carrier gas carries the separated oxygen out through the f port and the e port, while the remaining hydrocarbons remain in the first chromatographic column 5.

[0067] Step S3: After time t1, the first ten-way valve 1 is switched to the OFF state from the ON state. The second carrier gas is introduced sequentially through the h port and the i port, and the residual sample gas in the first chromatographic column 5 is sent sequentially through the f port and the g port to the second chromatographic column 6. The second chromatographic column 6 separates the residual sample gas and sends it sequentially to the FID detector 9 by the second carrier gas for hydrocarbon analysis.

[0068] Specifically, in step S3, after the first ten-way valve 1 is switched to the ON state and maintained for a period of time, the oxygen in the sample gas is separated in the first four-column chromatographic column. If purging continues, the separated hydrocarbons will be blown out of the first column 5 and discharged, making subsequent analysis impossible. Therefore, it is necessary to switch to the OFF state in a timely manner. In one embodiment, after a time t1, the first ten-way valve 1 is switched to the ON state, it is switched back to the OFF state. Preferably, the time t1 is 0.5 min to 1.0 min.

[0069] At this time, when the first ten-way valve 1 is in the OFF state, the connection method between each port and the movement method of each gas are the same as in the OFF state described above. Therefore, the second carrier gas enters from port h, passes sequentially through port i, the first chromatographic column 5, port f, port g, the second chromatographic column 6, and the FID detector 9, thereby purging the hydrocarbons in the first chromatographic column 5 into the second chromatographic column 6. The second chromatographic column 6 is an N-column filled with a porous polymer. The pore size of the porous polymer is 60-80 mesh, and the second chromatographic column 6 is used to separate hydrocarbons such as methane, ethylene, acetylene, ethane, propylene, and propane.

[0070] Therefore, hydrocarbons are separated sequentially within the second chromatographic column 6 and enter the FID detector 9 sequentially. After a period of analysis, the FID detector 9 completes the analysis, obtaining chromatograms of methane, ethylene, acetylene, ethane, propylene, propane, etc., in the sample gas.

[0071] Step S4: After the first ten-way valve 1 is switched to the ON state for time t2, the second ten-way valve 2 is switched to the ON state. The third carrier gas backflushes the sample gas in the second quantitative tube 4 through ports D and C in sequence. The sample gas is then fed into the fourth chromatographic column 8 by the third carrier gas through ports J and I in sequence. The fourth chromatographic column 8 separates the oxygen in the sample gas and discharges it through ports F and E in sequence, leaving the residual sample gas in the fourth chromatographic column 8.

[0072] Specifically, in step S4, after the first ten-way valve 1 is switched to the ON state for time t2, all hydrocarbon substances in the first chromatographic column 5 have been blown into the second chromatographic column 6 for separation and analysis of individual hydrocarbons. Therefore, the relevant operations for total hydrocarbon analysis can be performed. Preferably, time t2 is 4.5 min to 5.5 min.

[0073] After the 20th valve 2 is switched to the ON position, the connection method of each port and the movement path of each gas are as follows:

[0074] Port A is connected to port B. The sample gas delivered from port 1 (the tenth valve) is discharged through port A and port B to port 2 (the twentyth valve).

[0075] Port D is connected to port C. Port C is connected to one end of the second quantitative tube 4. The other end of the second quantitative tube 4 is connected to port J. Port J is connected to port I. Port I is connected to one end of the fourth chromatographic column 8. The other end of the fourth chromatographic column 8 is connected to port F. Port F is connected to port E.

[0076] Therefore, the third carrier gas is input through port D, and sequentially passes through port C, the second quantitative tube 4, port J, port I, the fourth chromatographic column 8, port F, and port E to backflush the sample gas in the second quantitative tube 4 into the fourth chromatographic column 8 for separation. The fourth chromatographic column 8 is a Q-column packed with porous polymer microspheres. The pore size of the porous polymer microspheres is 60-80 mesh, allowing the fourth chromatographic column 8 to separate oxygen and hydrocarbons from the sample gas. The separated oxygen is purged by the third carrier gas and discharged through ports F and E, while the remaining hydrocarbons remain in the fourth chromatographic column 8.

[0077] Step S5: The 20th valve 2 is in the ON state for time t3, then switches to the OFF state. The fourth carrier gas is introduced sequentially through port G and port F, and the residual sample gas in the fourth column 8 is sent sequentially through port I, port H and the third column 7 to the FID detector 9 for total hydrocarbon analysis.

[0078] Specifically, in step S5, after time t3 when the 20th valve 2 is in the ON state, the oxygen in the sample gas is separated in the fourth chromatographic column 8. If purging continues, the separated hydrocarbons will be blown out of the fourth chromatographic column 8 and discharged, making subsequent analysis impossible. Therefore, it is necessary to switch to the OFF state in a timely manner. Preferably, time t3 is 4.55 min-5.55 min and t3 > t2, thereby ensuring that oxygen is separated and discharged in a timely manner while hydrocarbons can still be retained in the fourth chromatographic column 8.

[0079] When the 20th valve 2 is switched to the OFF state, its port connection method and the movement path of each gas are consistent with the OFF state of the 20th valve 2 in the above steps. Therefore, after the 20th valve 2 is switched back to the OFF state, the fourth carrier gas can be introduced sequentially through port G and port F, and the hydrocarbons in the fourth chromatographic column 8 can be sent sequentially through port I, port H, and the third chromatographic column 7 to the FID detector 9 for total hydrocarbon analysis. In one embodiment, the third chromatographic column 7 is a glass microcolumn filled with silanized glass microspheres with a pore size of 60-80 mesh. The third chromatographic column 7 is used to improve the efficiency of total hydrocarbon analysis by utilizing the empty column effect, that is, the total hydrocarbons enter the empty column without interacting with the tube wall, and directly respond on the FID detector. After the third chromatographic column 7 separates the hydrocarbons, the hydrocarbons enter the FID detector 9 for total hydrocarbon analysis, thereby obtaining a chromatogram of total hydrocarbons.

[0080] In one embodiment, the first, second, third, and fourth carrier gases are ultra-pure nitrogen gases with a purity of 6N or higher, and are respectively delivered to the corresponding ports of the first ten-way valve 1 and the second ten-way valve 2 via the same gas delivery pipeline. This arrangement avoids the introduction of impurities into the high-purity carrier gases, thus preventing any impact on analytical accuracy. Distributing the gases to their corresponding ports via the same pipeline also avoids analytical errors caused by differences between the carrier gases.

[0081] In addition, the first carrier gas, the second carrier gas, the third carrier gas and the fourth carrier gas are continuously supplied, thereby maintaining purging and preventing the entry of external impurity gases.

[0082] In one embodiment, the method for analyzing total hydrocarbons and individual hydrocarbons in oxygen further includes steps S6 and S7.

[0083] Step S6: Use a first standard gas to calibrate the total hydrocarbon content in oxygen. The first standard gas is a standard gas with oxygen as the background gas and containing 5 ppm of methane.

[0084] Specifically, in step S6, the first standard gas is operated using the method described above for measuring total hydrocarbons to obtain a standard curve for total hydrocarbons. Preferably, obtaining the standard curve for total hydrocarbons requires three consecutive injections, and the RSD (relative standard deviation) of the peak areas for the three injections must be less than 3%.

[0085] Step S7: Use a second standard gas to calibrate the content of each hydrocarbon component in oxygen. The second standard gas uses oxygen as the background gas and prepares standard gases of 1 ppm methane, 1 ppm ethylene, 1 ppm acetylene, 1 ppm propylene, and 1 ppm propane.

[0086] Specifically, in step 7, the second standard gas is operated using the method described above for measuring individual hydrocarbons to obtain a standard curve for the individual hydrocarbons. Preferably, obtaining the standard curve for the individual hydrocarbons requires three consecutive injections, and the RSD (relative standard deviation) of the peak areas for the three injections must be <3%.

[0087] The component content in the sample is calculated according to the following formula (1):

[0088] Φ i =( A i / A s )* Φ s -----------(1)

[0089] In the formula:

[0090] Φ i --The content of component i in the sample gas, in ppm.

[0091] Φ s—The content of component i in the standard gas, in ppm.

[0092] A i -- The peak area (pA.s) of component i in the sample gas corresponding to the spectrum.

[0093] A s --Peak area size (pA.s) of component i in the standard gas spectrum.

[0094] The arithmetic mean of two parallel measurements of the sample is taken as the final analytical result, and the relative deviation between the two measurements should not exceed ±10%. It should be noted that the total hydrocarbon (THC) content calculated should specify that the total hydrocarbons (THC) are calculated based on methane.

[0095] In summary, the analytical apparatus and method for analyzing total hydrocarbons and individual hydrocarbons in oxygen of the present invention can simultaneously operate and add samples to two quantitative tubes using the same gas path, improving sample addition efficiency. The dual-valve, four-column setup allows for simultaneous analysis of total hydrocarbons and individual hydrocarbons, and is simple and easy to operate. Furthermore, before analysis, the method separates and discharges oxygen outside the gas path, thus completely removing interference from the main peak against the oxygen background, resulting in good separation, uniform peak shape, and meeting testing requirements.

[0096] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0097] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An apparatus for analyzing total hydrocarbons and individual hydrocarbons in oxygen, characterized by, The first tenth valve with ports a-j, the second tenth valve with ports A-J, the first constant flow tube, the second constant flow tube, the first chromatographic column, the second chromatographic column, the third chromatographic column, the fourth chromatographic column and the FID detector; The b port of the first tenth valve is in communication with the A port of the second tenth valve; the first constant flow tube is in communication with the c port and the j port of the first tenth valve; one end of the first chromatographic column is in communication with the i port and the other end is in communication with the f port; one end of the second chromatographic column is in communication with the g port and the other end is in communication with the FID detector; the second constant flow tube is in communication with the C port and the J port of the second tenth valve, one end of the third chromatographic column is in communication with the H port and the other end is in communication with the FID detector; one end of the fourth chromatographic column is in communication with the F port and the other end is in communication with the I port; The first carrier gas is introduced from the d port, the second carrier gas is introduced from the h port, the third carrier gas is introduced from the D port, the fourth carrier gas is introduced from the G port, and the sample gas is introduced from the a port; The first tenth valve and the second tenth valve have OFF state and ON state; In the OFF state, the a port of the first tenth valve is in communication with the j port, the c port is in communication with the b port, the d port and the e port are in communication, the f port and the g port are in communication, and the h port and the i port are in communication; the A port of the second tenth valve is in communication with the J port, the C port is in communication with the B port, the D port is in communication with the E port, the G port is in communication with the F port, and the I port is in communication with the H port; In the ON state, the a port of the first tenth valve is in communication with the b port, the d port is in communication with the c port, the j port is in communication with the i port, and the f port is in communication with the e port; the A port of the second tenth valve is in communication with the B port, the D port is in communication with the C port, the J port is in communication with the I port, the F port is in communication with the E port, and the G port is in communication with the H port.

2. A method for analyzing total hydrocarbons and individual hydrocarbons in oxygen, characterized by, The analysis method using the analysis device of claim 1, comprising the following steps: Both the first tenth valve and the second tenth valve are in the OFF state, and the sample gas to be measured is sequentially conveyed through the a port and the j port to the first constant flow tube and fills the first constant flow tube; the excess sample gas is sequentially conveyed from the first constant flow tube through the c port, the b port, and the A port and the J port to the second constant flow tube and fills the second constant flow tube, and the excess sample gas is discharged from the second tenth valve; The first tenth valve is switched to the ON state, the first carrier gas is sequentially introduced from the d port and the c port into the first constant flow tube and back-flushed to the sample gas in the first constant flow tube, and then the first carrier gas carries the sample gas to sequentially enter the first chromatographic column from the j port and the i port; the first chromatographic column separates the oxygen in the sample gas and sequentially discharges from the f port and the e port, and the residual sample gas remains in the first chromatographic column; The first tenth valve is switched to the OFF state after t1 time in the ON state, the second carrier gas is sequentially introduced through the h port and the i port and the residual sample gas in the first chromatographic column is sequentially sent to the second chromatographic column through the f port and the g port; the second chromatographic column separates the residual sample gas and sequentially sends it to the FID detector for individual hydrocarbon analysis; The analysis method using the analysis device of claim 1, comprising the following steps: After the first tenth valve is switched to ON state for t2 time, the second tenth valve is switched to ON state, and the third carrier gas sequentially reversely blows the sample gas in the second constant-volume tube through D and C ports, and the sample gas is sequentially sent into the fourth chromatographic column from J and I ports by the third carrier gas; the fourth chromatographic column separates oxygen in the sample gas and sequentially discharges from F and E ports, and residual sample gas remains in the fourth chromatographic column; After the second tenth valve is switched to OFF state for t3 time, the fourth carrier gas is sequentially introduced through G and F ports, and the residual sample gas in the fourth chromatographic column is sequentially sent into the FID detector through I, H and third chromatographic column for total hydrocarbon analysis.

3. The method of analysis of total and speciated hydrocarbons in oxygen according to claim 2, wherein, The t1 time is 0.5 min-1.0 min.

4. The method of claim 2, wherein the total hydrocarbons in the oxygen gas are analyzed by the following steps of: The t2 time is 4.5 min-5.5 min, the t3 time is 4.55 min-5.55 min, and t3>t2.

5. The method of claim 1, wherein, The first chromatographic column is a Q column filled with high-porosity microspheres, the pore size of the high-porosity microspheres is 60-80 mesh, and the first chromatographic column is used for separating oxygen and hydrocarbon substances; The second chromatographic column is an N column filled with porous polymers, the pore size of the porous polymers is 60-80 mesh, and the second chromatographic column is used for separating methane, ethylene, acetylene, ethane, propylene, propane and other hydrocarbon substances; The third chromatographic column is a glass microcolumn filled with silanized glass microspheres, the pore size of the silanized glass microspheres is 60-80 mesh, and the third chromatographic column is used for total hydrocarbon analysis by empty column effect; The fourth chromatographic column is a Q column filled with high-porosity microspheres, the pore size of the high-porosity microspheres is 60-80 mesh, and the fourth chromatographic column is used for separating oxygen and hydrocarbon substances.

6. The method of analysis of total and speciated hydrocarbons in oxygen according to claim 1, wherein, The capacity of the first constant-volume tube is 0.5 ml, and the capacity of the second constant-volume tube is 0.2 ml.

7. The method of claim 1, wherein, The first carrier gas, the second carrier gas, the third carrier gas and the fourth carrier gas are ultra-pure nitrogen with a purity of 6N or above.

8. The method of claim 1, wherein, The first carrier gas, the second carrier gas, the third carrier gas and the fourth carrier gas are respectively delivered to the corresponding ports of the first tenth valve and the second tenth valve through the same gas delivery pipeline, and the first carrier gas, the second carrier gas, the third carrier gas and the fourth carrier gas are in a continuous introduction state.

9. The method of claim 1, wherein, Further comprising: A first standard gas is used to calibrate the total hydrocarbon content in oxygen, and the first standard gas is a standard gas with oxygen as a background gas and containing 5 ppm of methane component; A second standard gas is used to calibrate the content of each item hydrocarbon in oxygen, and the second standard gas is a standard gas with oxygen as a background gas and containing 1 ppm of methane, 1 ppm of ethylene, 1 ppm of acetylene, 1 ppm of propylene and 1 ppm of propane.

10. The method of claim 1, wherein, The introduction time of the sample gas is 0.2 min-0.5 min.

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