Chromatographic analysis system for trace amounts of hydrocarbons and carbon content in a gas

Abstract

The utility model discloses a kind of trace hydrocarbon and carbon content chromatographic analysis system in gas, by ten-way valve, six-way valve, four-way valve, first chromatographic column, second chromatographic column, third chromatographic column, FID detector, first resistance valve, second resistance valve, quantitative tube and conversion tube composition;Ten-way valve has 10 interfaces;Six-way valve has 6 interfaces;Four-way valve has 4 interfaces;Sample enters from the interface 9 of ten-way valve, from the interface 10 of ten-way valve exit;The interface 4 of four-way valve is connected with FID detector;Conversion tube one end is connected with the interface 1 of four-way valve and hydrogen inlet, the other end is connected with the interface 2 of four-way valve.Through trace hydrocarbon and carbon content chromatographic analysis system in gas, realize once sampling, required component is separated one-time, trace gas is detected by FID, and content is calculated by external standard method.Trace carbon monoxide, carbon dioxide pass through methane conversion tube, and after being converted into methane, it is detected by FID, and content is calculated by external standard method.

Description

Technical Field

[0001] This utility model relates to the field of chromatographic analysis, and in particular to a chromatographic analysis system for trace hydrocarbons and carbon content in gases. Background Technology

[0002] The determination of trace carbon content in gases includes hydrocarbons, trace carbon monoxide, and carbon dioxide. Trace hydrocarbons can be separated by a single chromatographic column and detected using FID, while trace carbon monoxide and carbon dioxide can be converted from methane and detected using FID.

[0003] In routine analytical control, all hydrocarbon components are measured through conversion tubes, which cause significant contamination and affect the lifespan of these tubes. If Hayesep R or carbon molecular sieve columns are used for separation, the separation of trace amounts of carbon monoxide from oxygen, nitrogen, etc., is poor, affecting the accurate determination of low concentrations of carbon monoxide.

[0004] If a molecular sieve column is used to separate trace amounts of carbon monoxide from oxygen, nitrogen, etc., carbon dioxide will be adsorbed by the molecular sieve, making it impossible to determine the carbon dioxide content. Furthermore, other multicarbon hydrocarbons cannot smoothly elute from the column and be detected. Summary of the Invention

[0005] To address the aforementioned problems, this utility model provides a chromatographic analysis system for trace hydrocarbons and carbon content in gases, comprising a ten-way valve, a six-way valve, a four-way valve, a first chromatographic column, a second chromatographic column, a third chromatographic column, an FID detector, a first resistance valve, a second resistance valve, a quantitative tube, and a conversion tube; the ten-way valve has 10 ports, designated as ports 1-10; the six-way valve has 6 ports, designated as ports 1-6; the four-way valve has 4 ports, designated as ports 1-4; the first and second resistance valves are needle valves, with the first resistance valve connected to port 6 of the ten-way valve, and the two ends of the second resistance valve connected to ports 4 and 5 of the six-way valve; a first carrier gas... A 10-way valve is connected to port 2, and a second carrier gas is connected to port 5. The quantitative tube is positioned between ports 1 and 8 of the 10-way valve. The sample enters through port 9 and exits through port 10. Port 7 of the 10-way valve is connected to port 3 via a first chromatographic column. Port 4 of the 10-way valve is connected to port 6 of a 6-way valve via a second chromatographic column. Port 1 of the 6-way valve is connected to port 2 of the 6-way valve via a third chromatographic column. Port 3 of the 6-way valve is connected to port 3 of a 4-way valve. Port 4 of the 4-way valve is connected to the FID detector. One end of the conversion tube is connected to port 1 of the 4-way valve and the hydrogen inlet, and the other end is connected to port 2 of the 4-way valve. The 10-way valve is silanized and used for gas sample injection and backflushing. The 6-way valve allows the sample gas to selectively enter the 4-way valve via the third chromatographic column or via a bypass. The 4-way valve allows the sample gas to selectively enter the FID detector via the methane conversion tube or via a bypass. The first and second resistance valves provide resistance, with the first valve providing resistance equivalent to the sum of the resistances of the second and third columns, and the second valve providing resistance equivalent to the resistance of the third column. Both the first and second carrier gases are high-purity nitrogen, used at a flow rate of 25–40 mL / min. The chromatographic separation temperature is 50–100 °C, ensuring separation efficiency.

[0006] Furthermore, the first chromatographic column is a Hayesep R stainless steel packed column with a diameter of φ3~4mm*0.5~1.5m, the second chromatographic column is a Hayesep R stainless steel packed column with a diameter of φ3~4mm*1.5~2.5m, and the third chromatographic column is a 5A molecular sieve stainless steel packed column with a diameter of φ3-4mm*4-7m.

[0007] Furthermore, the conversion tube is a methanation conversion tube with a diameter of 3~4mm and a length of 5~10cm filled with nickel.

[0008] The above-mentioned technical solution of this utility model has the following beneficial technical effects: Through a gas trace hydrocarbon and carbon content chromatographic analysis system, the required components are separated in a single injection. Trace amounts of methane, ethane, ethylene, acetylene, propane, etc., are detected by FID, and their content is calculated using the external standard method. Trace amounts of carbon monoxide and carbon dioxide are converted to methane through a methane conversion tube and then detected by FID, with their content calculated using the external standard method. A ten-way valve backflush injection technology is used to achieve the backflush function for heavy components. When the required components enter the separation column, unwanted components in the pre-column are backflushed out of the column to vent, preventing contamination of the column and detector by heavy components. A six-way valve switching system is used to separate carbon monoxide, argon, nitrogen, methane, etc., on a 5A molecular sieve column. Other components harmful to the 5A molecular sieve, such as carbon dioxide and various heavy hydrocarbon components, enter the detector through a bypass, avoiding damage to the 5A molecular sieve column. Trace amounts of carbon monoxide were separated using a 5A molecular sieve column, and trace amounts of carbon dioxide were separated using a Hayesep R column and then entered a methanation conversion tube. After conversion to methane, the methane was detected by a fractional-inductively coupled (FID) detector. A four-way valve was used to switch the flow of carbon monoxide and carbon dioxide into the methanation conversion tube, while other hydrocarbons bypassed the tube to the detector, protecting the tube and extending its lifespan. The detection limit using an FID detector was 0.1 × 10⁻⁶ mol / mol. Attached Figure Description

[0009] Figure 1 This is a gas path diagram for the chromatographic analysis system for trace hydrocarbons and carbon content in gases;

[0010] Figure 2 This is a diagram showing the injection status of a chromatographic analysis system for trace hydrocarbons and carbon content in gases, used to determine the trace carbon dioxide valve.

[0011] Figure 3 This is a diagram showing the hydrocarbon valve for determining the injection status of a chromatographic analysis system for trace hydrocarbons and carbon content in gases.

[0012] Figure 4 This is a backflush status valve diagram for a gas chromatography system for analyzing trace hydrocarbons and carbon content. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this utility model. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of this utility model.

[0014] like Figure 1As shown, a chromatographic analysis system for trace hydrocarbons and carbon content in gases is provided, comprising a ten-way valve V1, a six-way valve V2, a four-way valve V3, chromatographic columns 1, 2, and 3, an FID detector, resistance valve 1, resistance valve 2, a quantitative tube, and a conversion tube. The ten-way valve V1 has 10 ports, designated as ports 1-10; the six-way valve V2 has 6 ports, designated as ports 1-6; and the four-way valve V3 has 4 ports, designated as ports 1-4. Resistance valves 1 and 2 are needle valves; resistance valve 1 is connected to port 6 of the ten-way valve V1, and both ends of resistance valve 2 are connected to ports 4 and 5 of the six-way valve V2. Carrier gas 1 is connected to port 2 of the ten-way valve V1, and carrier gas 2 is connected to... The sample enters through port 5 of the 10-way valve V1; the quantitative tube is positioned between ports 1 and 8 of the 10-way valve V1; the sample enters through port 9 of the 10-way valve V1 and exits through port 10 of the 10-way valve V1; port 7 of the 10-way valve V1 is connected to port 3 of the 10-way valve V1 via column 1; port 4 of the 10-way valve V1 is connected to port 6 of the 6-way valve V2 via column 2; port 1 of the 6-way valve V2 is connected to port 2 of the 6-way valve V2 via column 3; port 3 of the 6-way valve V2 is connected to port 3 of the 4-way valve V3; port 4 of the 4-way valve V3 is connected to the FID detector; one end of the conversion tube is connected to port 1 of the 4-way valve V3 and the hydrogen inlet, and the other end is connected to port 2 of the 4-way valve V3. Ten-way valve V1, silanized, is used for gas sample injection and backflushing. Six-way valve V2 allows sample gas to selectively pass through column 3 or bypass into four-way valve V3. Four-way valve V3 allows sample gas to selectively pass through a methane converter or bypass into the FID detector. Resistance valves 1 and 2 provide resistance; resistance valve 1 provides a resistance equivalent to the sum of the resistances of column 2 and column 3, and resistance valve 2 provides a resistance equivalent to the resistance of column 3. Carrier gas 1 and carrier gas 2 are both high-purity nitrogen, used at a flow rate of 25–40 mL / min. The chromatographic separation temperature is 50–100 °C, ensuring separation efficiency.

[0015] Column 1 is a Hayesep R stainless steel packed column with a diameter of 3-4 mm and a length of 0.5-1.5 m; column 2 is a Hayesep R stainless steel packed column with a diameter of 3-4 mm and a length of 1.5-2.5 m; column 3 is a 5A molecular sieve stainless steel packed column with a diameter of 3-4 mm and a length of 4-7 m. The conversion tube is a nickel-filled methanation conversion tube with a diameter of 3-4 mm and a length of 5-10 cm.

[0016] The separation and analysis process is implemented as follows: After the sample gas fills the quantitative tube, switch to V1 for injection. Argon, nitrogen, methane, and carbon monoxide flow out of column 2 and enter column 3. Then switch to V2 so that carbon dioxide and other gases, after being separated by the first two columns, enter the methane conversion tube through the bypass via resistance valve 2. Then switch to V3 so that ethylene, ethane, acetylene, propane, and other gases separated by the first two columns enter the detector through the bypass.

[0017] Once all the components to be measured have entered column 2, the ten-way valve V1 is used to backflush out the system of the impurities that do not need to be measured in column 1, thus preventing them from entering the system and contaminating the column, methane conversion tube and detector.

[0018] V3 is a selection valve that allows components that need to be methanated before they can be measured to be directly fed into the detector via a bypass, thus improving the service life of the methanation tube.

[0019] Resistance valve 1 provides the sum of the pressures of column 2 and column 3 to prevent the gas path system pressure from dropping after backflushing the valve, which would cause the chromatograph to malfunction. Resistance valve 2 provides the same pressure as column 3 to ensure that the carrier gas flow rate is stable after switching to the bypass.

[0020] During the specific inspection:

[0021] Select 1.0m column 1, 2.0m column 2, and 6.0m column 3, connect the columns, set the carrier gas flow rate to 30mL / min, and the column oven temperature to 105℃. The calibration method yields the following valve switching time schedule:

[0022]

[0023] 1. At 0.01 min, V1 switches to the injection state, and the sample gas enters the chromatographic column 1 and chromatographic column 2 for separation, and then enters the chromatographic column 3.

[0024] 2. At 0.98 min, oxygen, nitrogen, carbon monoxide, and methane flow out of column 2 and into column 3. Carbon dioxide is about to flow out of the column. Switch V2 to bypass so that carbon dioxide enters the methane conversion furnace through the bypass.

[0025] 3. After 2.80 min, carbon dioxide flows out of the methane conversion tube and is detected by the FID detector. Ethane, ethylene, acetylene, and propane are about to flow out of column 2. Switch V3 to bypass so that the above components can directly enter the FID detector for detection.

[0026] 4. After 6.50 min of hydrocarbon detection, switch V2 to series to separate methane and carbon monoxide sealed in column 3.

[0027] 5. At 8:80 min, methane effluents from column 3 and is detected by the FID detector. Carbon monoxide is about to effluent from column 3. Switch V3 to series so that carbon monoxide passes through the methanation conversion tube and is converted into methane, which is then detected by the FID detector. After the analysis is completed, the method operation is finished.

[0028] Figure 2 This is a diagram of the valve for measuring trace amounts of carbon dioxide during sample introduction. Figure 3 This is a diagram showing the hydrocarbon injection state for determination. Figure 4 This is a diagram of the backflush valve.

[0029] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of this utility model and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of this utility model should be included within its protection scope. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A chromatographic analysis system for trace hydrocarbons and carbon content in gases, characterized in that, It consists of a 10-way valve, a 6-way valve, a 4-way valve, a first chromatographic column, a second chromatographic column, a third chromatographic column, an FID detector, a first resistance valve, a second resistance valve, a quantitative tube, and a conversion tube. The 10-way valve has 10 ports, designated as ports 1-10; the 6-way valve has 6 ports, designated as ports 1-6; and the 4-way valve has 4 ports, designated as ports 1-4. The first and second resistance valves are needle valves. The first resistance valve is connected to port 6 of the 10-way valve, and the two ends of the second resistance valve are connected to ports 4 and 5 of the 6-way valve. The first carrier gas is connected to port 2 of the 10-way valve, and the second carrier gas is connected to port 5 of the 10-way valve. The valve has an interface 5; the quantitative tube is positioned between interfaces 1 and 8 of the ten-way valve; the sample enters from interface 9 of the ten-way valve and exits from interface 10 of the ten-way valve; interface 7 of the ten-way valve is connected to interface 3 of the ten-way valve via the first chromatographic column; interface 4 of the ten-way valve is connected to interface 6 of the six-way valve via the second chromatographic column; interface 1 of the six-way valve is connected to interface 2 of the six-way valve via the third chromatographic column; interface 3 of the six-way valve is connected to interface 3 of the four-way valve; interface 4 of the four-way valve is connected to the FID detector; one end of the conversion tube is connected to interface 1 of the four-way valve and the hydrogen inlet, and the other end is connected to interface 2 of the four-way valve.

2. The chromatographic analysis system for trace hydrocarbons and carbon content in gas according to claim 1, characterized in that, The first chromatographic column is a Hayesep R stainless steel packed column with a diameter of φ3~4mm*0.5~1.5m; the second chromatographic column is a Hayesep R stainless steel packed column with a diameter of φ3~4mm*1.5~2.5m; and the third chromatographic column is a 5A molecular sieve stainless steel packed column with a diameter of φ3-4mm*4-7m.

3. The chromatographic analysis system for trace hydrocarbons and carbon content in gas according to claim 1, characterized in that, The conversion tube is a methanation conversion tube with a diameter of 3~4mm and a length of 5~10cm, filled with nickel.

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