Online chromatographic separation and detection system for natural gas components

Abstract

The utility model belongs to the technical field of industrial on-line gas chromatographic analysis and detection, and particularly discloses an on-line chromatographic separation and detection system for natural gas components. The method is used for solving the problems that multiple paths of carrier gas are needed and the analysis scheme is complex when the traditional gas chromatography is used for analyzing the natural gas composition. The system comprises a quantitative loop for quantifying a sample, a ten-way valve and two six-way valves for controlling sample introduction and reverse blowing, four chromatographic columns for separating the sample, two damping tubes for controlling pressure balance, and a thermal conductivity detector for detecting natural gas components. The two communicated valve ports of the ten-way valve and the six-way valve in the switching state are disconnected and then connected to the other adjacent valve port. According to the utility model, only one path of carrier gas is needed, so that the gas source consumption is saved. By adopting three valves, four chromatographic columns and one detector, the system configuration is simple, the analysis of complex samples can be quickly completed, the analysis efficiency is improved, the production process is helped to be optimized, and the yield is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of industrial on-line gas chromatography analysis and detection, and particularly relates to an on-line chromatographic separation and detection system for natural gas components. Background Art

[0002] As an important energy source, the component analysis of natural gas is of great significance for its quality evaluation, storage, transportation and utilization. Traditional methods for natural gas composition analysis include mass spectrometry, infrared spectroscopy, sensor method, gas chromatography, etc. In comparison, mass spectrometry is expensive and requires large equipment investment. It is more suitable for laboratory analysis. In addition, the equipment cost and maintenance cost are high, and professional personnel may be required for operation and maintenance. Infrared spectroscopy may be interfered by other components in the gas, resulting in inaccurate results. Infrared can usually only detect one or a few components, which may not be accurate enough for complex natural gas composition analysis. The sensor method may be affected by environmental factors such as temperature and humidity, resulting in unstable results. In addition, the service life and accuracy of the sensor may be limited, and it needs to be replaced and calibrated regularly.

[0003] Gas chromatography is an efficient and accurate chemical analysis method, especially suitable for the analysis of natural gas components. Through a specific chromatographic column, gas chromatography can efficiently separate the components in natural gas and use a highly sensitive detector for quantitative analysis. This method has excellent separation effect and accuracy, and can provide reliable data support, so it is widely used in the natural gas industry, environmental protection and other fields.

[0004] Traditional gas chromatography often uses multiple detectors or multiple carrier gases to analyze the composition of natural gas, which requires a lot of carrier gases and a complex analysis scheme. The design of multiple detectors and multiple carrier gases is often more troublesome in data processing. Utility Model Content

[0005] The utility model aims to provide an online chromatographic separation and detection system for natural gas components, which effectively solves the problem that the traditional gas chromatography method needs multiple carrier gases and a complex analysis scheme when analyzing the composition of natural gas.

[0006] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0007] An online chromatographic separation and detection system for natural gas components comprises a quantitative loop for sample quantification, a ten-way valve and two six-way valves for controlling injection and back-flushing, four chromatographic columns for sample separation, two damping tubes for controlling pressure balance and a thermal conductivity detector for natural gas component detection.

[0008] The ten-way valve includes five pairs of valve ports connected in pairs, namely, valve port a and valve port j connected, valve port b and valve port c connected, valve port e and valve port d connected, valve port g and valve port f connected, and valve port h and valve port i connected.

[0009] The valve port a of the ten-way valve is adjacent to the valve port b, the valve port c is adjacent to the valve port d, the valve port e is adjacent to the valve port f, the valve port g is adjacent to the valve port h, and the valve port i is adjacent to the valve port j.

[0010] The six-way valve includes three pairs of valve ports connected in pairs, namely valve port A and valve port B connected, valve port E and valve port F connected, and valve port D and valve port C connected.

[0011] The valve port A and the valve port F of the six-way valve are adjacent to each other, the valve port E and the valve port D are adjacent to each other, and the valve port C and the valve port B are adjacent to each other.

[0012] When the ten-way valve and the six-way valve are in an open state, two valve ports that are already connected will be disconnected and connected to another adjacent valve port.

[0013] The valve port i of the ten-way valve is the sample inlet, the valve port j is the sample outlet, the valve port g is the carrier gas inlet, the quantitative loop is connected between the valve ports a and h, the first chromatographic column is connected between the valve ports e and b, and the valve port c is connected to the thermal conductivity detector.

[0014] The second chromatographic column is connected between valve port E and valve port D of the first six-way valve, the first damping tube is connected between valve port A and valve port B, and the third chromatographic column is connected between valve port f of the ten-way valve and valve port F of the first six-way valve.

[0015] The fourth chromatographic column is connected between the valve port E and the valve port D of the second six-way valve, and the second damping tube is connected between the valve port A and the valve port B.

[0016] The valve port d of the ten-way valve is connected to the valve port C of the second six-way valve, and the valve port C of the first six-way valve is connected to the valve port F of the second six-way valve.

[0017] Furthermore, the ten-way valve, the first six-way valve and the second six-way valve are all diaphragm valves.

[0018] Further, the damping of the first damping tube is consistent with the damping of the second chromatographic column, and the damping of the second damping tube is consistent with the damping of the first chromatographic column.

[0019] Furthermore, the first chromatographic column, the second chromatographic column, the third chromatographic column and the fourth chromatographic column are all 1 / 16-inch stainless steel chromatographic columns.

[0020] Compared with the prior art, the beneficial technical effects of the utility model are:

[0021] (1) The utility model only requires one carrier gas and one thermal conductivity detector, which helps to save gas source consumption. Regardless of whether the ten-way valve and the six-way valve are in an open or closed state, the thermal conductivity detector has carrier gas flowing, thereby ensuring the service life of the thermal conductivity detector.

[0022] (2) The utility model adopts three valves, four chromatographic columns and one detector. The system configuration is simple and can quickly complete the analysis of a large number of samples, improve the analysis efficiency, help optimize the production process, and thus improve the yield.

[0023] (3) The utility model ensures the stability of the flow rate in the valve-off state by making the damping of the first damping tube consistent with the damping of the second chromatographic column, and making the damping of the second damping tube consistent with the damping of the first chromatographic column, which is beneficial to ensuring the stability of the baseline during the analysis process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the connection structure of the utility model. DETAILED DESCRIPTION

[0025] An on-line chromatographic separation and detection system for natural gas components, such as Figure 1 As shown, it includes a quantitative loop 1 for sample quantification, a ten-way valve 2 and two six-way valves for controlling injection and backwashing, four chromatographic columns for sample separation, two damping tubes for controlling pressure balance, and a thermal conductivity detector 3 for natural gas component detection. The thermal conductivity detector 3 is used for the detection of hydrogen, helium, oxygen, nitrogen, carbon monoxide, carbon dioxide, components with 1-5 carbon atoms in the molecular formula (C1 to C5), and components with not less than 6 carbon atoms in the molecular formula (C6+).

[0026] The ten-way valve 2 includes five pairs of valve ports connected in pairs, namely, valve port a and valve port j connected, valve port b and valve port c connected, valve port e and valve port d connected, valve port g and valve port f connected, and valve port h and valve port i connected.

[0027] The valve port a of the ten-way valve 2 is adjacent to the valve port b, the valve port c is adjacent to the valve port d, the valve port e is adjacent to the valve port f, the valve port g is adjacent to the valve port h, and the valve port i is adjacent to the valve port j.

[0028] The six-way valve includes three pairs of valve ports connected in pairs, namely valve port A and valve port B connected, valve port E and valve port F connected, and valve port D and valve port C connected.

[0029] The valve port A and the valve port F of the six-way valve are adjacent to each other, the valve port E and the valve port D are adjacent to each other, and the valve port C and the valve port B are adjacent to each other.

[0030] The two valve ports of the ten-way valve 2 and the six-way valve that are already connected in the open state will be disconnected and connected to another adjacent valve port. Taking the ten-way valve 2 as an example, when the valve is closed, valve port b is connected to valve port c, and when the valve is opened, valve port b is connected to valve port a, and valve port c is connected to valve port d.

[0031] The valve port i of the ten-way valve 2 is the sample inlet, the valve port j is the sample outlet, the valve port g is the carrier gas inlet, the quantitative loop 1 is connected between the valve ports a and h, the first chromatographic column 4 is connected between the valve ports e and b, and the valve port c is connected to the thermal conductivity detector 3.

[0032] A second chromatographic column 6 is connected between valve port E and valve port D of the first six-way valve 5 , a first damping tube 7 is connected between valve port A and valve port B, and a third chromatographic column 8 is connected between valve port f of the ten-way valve 2 and valve port F of the first six-way valve 5 .

[0033] A fourth chromatographic column 10 is connected between valve port E and valve port D of the second six-way valve 9 , and a second damping tube 11 is connected between valve port A and valve port B.

[0034] The valve port d of the ten-way valve 2 is connected to the valve port C of the second six-way valve 9 , and the valve port C of the first six-way valve 5 is connected to the valve port F of the second six-way valve.

[0035] In this embodiment, the ten-way valve 2, the first six-way valve 5 and the second six-way valve 9 are all diaphragm valves. Compared with slider valves or rotor valves, diaphragm valves have extremely long service life, very short switching time, extremely small dead volume and ultra-high reliability, easy maintenance and cost saving.

[0036] In this embodiment, the damping of the first damping tube 7 is consistent with the damping of the second chromatographic column 6, and the damping of the second damping tube 11 is consistent with the damping of the first chromatographic column 4, thereby ensuring the stability of the flow in the valve cutting state, thereby ensuring the stability of the baseline during the analysis process.

[0037] Conventional online chromatography generally uses 1 / 8 inch stainless steel chromatographic columns. In this embodiment, the first chromatographic column 4, the second chromatographic column 6, the third chromatographic column 8 and the fourth chromatographic column 10 are all 1 / 16 inch stainless steel chromatographic columns. Compared with 1 / 8 inch stainless steel chromatographic columns, the carrier gas consumption required in this embodiment is lower.

[0038] This embodiment only requires one carrier gas, which helps to save gas consumption. Regardless of whether the ten-way valve 2 and the two six-way valves are in an open or closed state, the thermal conductivity detector 3 has carrier gas flowing, thereby ensuring the service life of the thermal conductivity detector 3.

[0039] In this embodiment, the carrier gas is argon.

[0040] The specific working process of this embodiment is as follows:

[0041] First, the ten-way valve 2, the first six-way valve 5 and the second six-way valve 9 are all in a closed state, the sample enters from the valve port i of the ten-way valve 2, and exits from the valve port j of the ten-way valve 2 after filling the quantitative ring 1, and the carrier gas passes through the third chromatographic column 8, the second chromatographic column 6, the fourth chromatographic column 10 and the first chromatographic column 4 in sequence before entering the thermal conductivity detector 3.

[0042] Open the ten-way valve 2 and the second six-way valve 9, and connect the carrier gas to the quantitative ring 1 through the valve port g of the ten-way valve 2, driving the gas in the quantitative ring 1 to enter the first chromatographic column 4, the third chromatographic column 8 and the second chromatographic column 6 in sequence.

[0043] When lighter components such as hydrogen, helium, oxygen, nitrogen, carbon monoxide, methane, carbon dioxide and ethane come out of the third chromatographic column 8 and enter the second chromatographic column 6, the first six-way valve 5 is opened to seal the above gases in the second chromatographic column 6.

[0044] When all components before C6+ have come out of the first chromatographic column 4, the C6+ component remains in the first chromatographic column 4, and the ten-way valve 2 is closed. The hydrocarbons from C3 to C5 are separated from the third chromatographic column 8 and enter the first chromatographic column 4. At this time, the first chromatographic column 4 is in a backflush state, and the C6+ in the first chromatographic column 4 flows out first and is quantified as an independent peak, followed by the C3-C5 hydrocarbons that flow out separately and are quantified by the thermal conductivity detector 3.

[0045] The first six-way valve 5 and the second six-way valve 9 are closed, and the carrier gas drives the hydrogen, helium, oxygen, nitrogen, carbon monoxide, methane and carbon dioxide gases in the second chromatographic column 6 into the fourth chromatographic column 10 .

[0046] After hydrogen, helium, oxygen, nitrogen, carbon monoxide and methane enter the fourth chromatographic column 10, the second six-way valve 9 is opened, and hydrogen, helium, oxygen, nitrogen, carbon monoxide and methane are sealed in the fourth chromatographic column 10, so that carbon dioxide cannot enter the fourth chromatographic column 10. At this time, carbon dioxide directly enters the thermal conductivity detector 3 for quantification.

[0047] The second six-way valve 9 is closed, and hydrogen, helium, oxygen, nitrogen, carbon monoxide and methane are separated in the fourth chromatographic column 10 and then enter the thermal conductivity detector 3 for quantification.

[0048] Finally, close the ten-way valve 2 and the first six-way valve 5.

[0049] The utility model adopts a three-valve, four-chromatographic column and one-detector method to quickly detect hydrogen, helium, oxygen, nitrogen, carbon monoxide, carbon dioxide, C1 to C5 and C6+ components in the natural gas being tested. The system configuration is simple, and it can quickly complete the analysis of a large number of samples, improve the analysis efficiency, help optimize the production process, and thus increase the yield.

[0050] The utility model can accurately control the production process and avoid unnecessary energy consumption and waste of raw materials. For example, by optimizing the production process parameters, energy consumption and raw material usage can be reduced, and production costs can be reduced. In addition, the utility model can realize automatic sample injection, analysis and data processing, reduce manual operations, and reduce errors.

[0051] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. An online chromatographic separation and detection system for natural gas components, characterized in that: It includes a quantitative loop for sample quantification, a ten-way valve and two six-way valves for controlling injection and back-flushing, four chromatographic columns for sample separation, two damping tubes for controlling pressure balance, and a thermal conductivity detector for natural gas component detection; The ten-way valve includes five pairs of valve ports connected in pairs, namely valve port a and valve port j connected, valve port b and valve port c connected, valve port e and valve port d connected, valve port g and valve port f connected, and valve port h and valve port i connected; The valve port a of the ten-way valve is adjacent to the valve port b, the valve port c is adjacent to the valve port d, the valve port e is adjacent to the valve port f, the valve port g is adjacent to the valve port h, and the valve port i is adjacent to the valve port j; The six-way valve includes three pairs of valve ports connected in pairs, namely valve port A and valve port B connected, valve port E and valve port F connected, and valve port D and valve port C connected; The valve port A and valve port F of the six-way valve are adjacent, the valve port E and valve port D are adjacent, and the valve port C and valve port B are adjacent; The two valve ports of the ten-way valve and the six-way valve that are already connected in the open state will be disconnected and connected to another adjacent valve port; The valve port i of the ten-way valve is the sample inlet, the valve port j is the sample outlet, the valve port g is the carrier gas inlet, the quantitative loop is connected between the valve ports a and h, the first chromatographic column is connected between the valve ports e and b, and the valve port c is connected to the thermal conductivity detector; A second chromatographic column is connected between valve port E and valve port D of the first six-way valve, a first damping tube is connected between valve port A and valve port B, and a third chromatographic column is connected between valve port f of the ten-way valve and valve port F of the first six-way valve; A fourth chromatographic column is connected between valve port E and valve port D of the second six-way valve, and a second damping tube is connected between valve port A and valve port B; The valve port d of the ten-way valve is connected to the valve port C of the second six-way valve, and the valve port C of the first six-way valve is connected to the valve port F of the second six-way valve.

2. The online chromatographic separation and detection system for natural gas components according to claim 1, characterized in that: The ten-way valve, the first six-way valve and the second six-way valve are all diaphragm valves.

3. The on-line chromatographic separation and detection system for natural gas components according to claim 2, characterized in that: The damping of the first damping tube is consistent with the damping of the second chromatographic column, and the damping of the second damping tube is consistent with the damping of the first chromatographic column.

4. The on-line chromatographic separation and detection system for natural gas components according to claim 3, characterized in that: The first chromatographic column, the second chromatographic column, the third chromatographic column and the fourth chromatographic column are all 1 / 16 inch stainless steel chromatographic columns.

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