Gas sampling replacement device based on negative pressure suction and gas sampling device

Abstract

The invention discloses a gas sampling and replacing device based on negative pressure suction and a gas sampling device. The gas sampling and replacing device based on negative pressure suction comprises a sampling pipeline, a pressure regulating pipeline and a Venturi tube, one end of the sampling pipeline is connected to the throat part of the Venturi tube, and the other end is connected with a gas collecting device; and the pressure regulating pipeline is connected with the inlet section of the Venturi tube and is used for introducing an inert medium, regulating the vacuum degree in the sampling pipeline and driving the sampling pipeline to suck the sample gas. The gas sampling device comprises a gas collecting device and a gas sampling and replacing device based on negative pressure suction. According to the device, unpowered sampling is realized through a Venturi tube negative pressure principle, the structure is simple, and the mounting cost is reduced by 40%; during sampling, pipe fittings do not need to be disassembled, the external gas mixing amount is smaller than or equal to 0.01%, the detection deviation of trace components (larger than or equal to 2 ppm) in sample gas is smaller than or equal to 2%, the problem of sample gas pollution caused by disassembly and assembly in traditional sampling is solved, and the method is particularly suitable for trace component analysis scenes in the petrochemical industry field.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas sampling, in particular to a gas sampling and replacement device based on negative pressure suction. BACKGROUND

[0002] In petrochemical production, gas sampling bags are often used to collect sample gas, and accurate analysis of trace components (such as oxygen, carbon monoxide, carbon dioxide, olefins, and sulfides) in the sample gas is critical for process control. When using a typical double-valve gas sampling bag, the inlet and outlet of the gas sampling bag are connected to the temporary gas sampling port of the gas sampling box through a hose, and then the gas in the gas sampling bag is discharged by squeezing. This process is repeated several times to clean the gas bag and replace the gas in the gas bag. The current double-valve gas sampling bag sampling method has significant defects: When manually squeezing and replacing, the residual gas volume accounts for 3.2%~4.8%, resulting in a 10 mL / m 3 The detection deviation of the following components is 20%~30%; Each sampling requires disassembly and assembly of the pipe at least 3 times, and about 0.5~2 mL of external air is mixed into the sample gas during each disassembly and assembly process, causing the oxygen content and carbon dioxide content to be 0.1%~0.5% higher than the detection value. For steel cylinder sampling, the traditional replacement method takes more than 30 minutes or even longer, and cannot meet the requirements of GB / T 7716-2024, GB / T 3634.2-2011, and GB / T 8979-2008 for trace component analysis (≤5 mL / m 3 ).

[0003] In the prior art, the negative pressure sampling device driven by a mechanical pump can reduce disassembly and assembly, but has problems such as high energy consumption (power ≥ 50W), poor explosion-proof performance, high maintenance cost, and is difficult to promote in the chemical industry. SUMMARY

[0004] Objective: To overcome the deficiencies in the prior art, the present application provides a gas sampling and replacement device based on negative pressure suction, which has a simple structure, high efficiency, and realizes unpowered sampling through the Venturi negative pressure principle, thereby improving sample gas purity and detection accuracy.

[0005] To solve the above technical problems, the technical solution adopted by the present application is:

[0006] In a first aspect, the present application provides a gas sampling and displacement device based on negative pressure suction, comprising: a sampling pipeline, a pressure regulating pipeline and a Venturi tube; one end of the sampling pipeline is sealingly connected to the throat of the Venturi tube, and the other end is connected to a gas collection device; the pressure regulating pipeline is connected to the inlet section of the Venturi tube, used for introducing inert medium, adjusting the vacuum degree in the sampling pipeline, and driving the sampling pipeline to suck sample gas at a flow rate of 0.3-2 L / min.

[0007] The introduction of inert medium reduces the pressure at the throat of the Venturi tube, and the negative pressure is generated by driving through the inert medium by using the throttling effect of the Venturi tube, so that the sample gas is sucked without additional power and the energy consumption is low; the inert medium as the driving medium does not react with the sample gas and the pipeline material, and can displace the residual gas in the sampling pipeline, prevent the sample gas from being contaminated, and improve the accuracy of subsequent analysis results.

[0008] In some embodiments, the pressure regulating pipeline comprises a first check valve, a needle valve and a pressure reducing valve in sequence after the inert medium is introduced; the pressure resistance of the first check valve is ≥1 MPa, used to prevent residual gas in the sampling pipeline and the gas collection device from mixing into the inert medium and causing contamination of the inert medium; the needle valve is used to control the flow rate of the inert medium in the pressure regulating pipeline; the pressure reducing range of the pressure reducing valve is 0.1-1 MPa, used to control the pressure of the inert medium in the pressure regulating pipeline; the needle valve and the pressure reducing valve cooperatively adjust the vacuum degree in the pressure regulating pipeline to -0.02 MPa to -0.08 MPa, and the adjustment response time is ≤3 seconds.

[0009] In some embodiments, the sampling pipeline comprises a ball valve and a second check valve in sequence after the sample gas is collected; the ball valve has a diameter of 6-10 mm, used to control the opening and closing of the sampling pipeline, and the opening and closing time is ≤2 seconds; the second check valve is used to prevent the inert medium from entering the gas collection device and contaminating the sample gas, and the reverse sealing pressure is ≥0.5 MPa.

[0010] In some embodiments, the sampling pipeline further comprises a vacuum gauge installed between the second check valve and the Venturi tube, used to display the vacuum degree value in the sampling pipeline in real time; the measurement range of the vacuum gauge is -0.1-0 MPa, and the accuracy is ±0.01 MPa.

[0011] In some embodiments, the inert medium is process nitrogen, the oxygen content is ≤5 ppm, the dew point is ≤-40℃, and the purity is ≥99.99%.

[0012] In some embodiments, the throat diameter of the Venturi tube is 3-8 mm, and the length of the inlet section of the Venturi tube is 5-8 times the throat diameter.

[0013] In a second aspect, the present application provides a gas sampling device, comprising a gas collection device and the negative pressure suction-based gas sampling displacement device according to the first aspect. Through the one-way valve and the sealed pipeline design, the disassembly of the pipe fittings during the sampling process is avoided, and the mixing of external gas is reduced.

[0014] The pressure regulating pipeline in the gas collection device can regulate the flow and pressure of the inert medium, and further regulate the vacuum degree in the sampling pipeline, so as to adapt to different sampling requirements.

[0015] In some embodiments, the gas collection device is a double-gas-port container with a fixed shape, with a volume of 0.5-10 L, comprising a first gas port and a second gas port; the first gas port is connected to the gas sampling displacement device, and the second gas port is connected to a gas sampling port of the sample gas; the working pressure of the gas sampling is 0.01-0.5 MPa.

[0016] In some embodiments, the first gas port is connected to the gas sampling displacement device through a φ6-10 mm hose, and the second gas port is connected to the gas sampling port of the sample gas through a corrosion-resistant hose.

[0017] In some embodiments, the gas collection device is a gas sampling bag, and the material of the gas sampling bag is polytetrafluoroethylene or aluminum plastic composite film, with a pressure resistance of 0.2-0.6 MPa. In some embodiments, the gas collection device is a gas sampling steel cylinder, and the material of the gas sampling steel cylinder is 316 stainless steel, with an inner wall roughness Ra≤0.8 μm.

[0018] Advantages:

[0019] (1) The negative pressure suction-based gas sampling displacement device provided by the present application can be installed on the site of a chemical device, and is suitable for the collection and analysis of gas samples containing trace components (1 ppm-1%) in the fields of petroleum chemical industry, coal chemical industry, etc.; the inert medium flows through the Venturi tube, the throat flow rate reaches 30-50 m / s, a stable negative pressure is formed, no electrical components are needed, the energy consumption of the suction process is 0, and the explosion-proof requirement is met. (2) The negative pressure suction-based gas sampling displacement device provided by the present application only uses conventional pipe fittings, and the entire device is simple, practical and efficient. (3) During the entire gas displacement and gas sampling process of the gas sampling device provided by the present application, the pipe fittings do not need to be disassembled, which effectively prevents a small amount of external air from entering the gas collection device during the disassembly process, the detection deviation of the trace components (1-100 ppm) in the sample gas is ≤2%, which is reduced by more than 10 times compared with the traditional method. (4) In the negative pressure suction-based gas sampling displacement device provided by the present application, the needle valve and the pressure reducing valve cooperatively regulate the vacuum degree, the control accuracy reaches ±0.02 MPa, and the residual gas is ≤0.05% after 3 displacements. (5) The total time for sampling and replacement by using the gas sampling and replacement device based on negative pressure suction provided by the application is less than or equal to 5 minutes, which is 83% shorter than the time for using the traditional method of steel cylinder. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only represent some of the embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0021] Figure 1 It is a schematic diagram of the overall structure of the gas sampling device based on negative pressure suction in the embodiments of the present application.

[0022] In the figure: 1, sampling pipeline, 11, ball valve, 12, second one-way valve, 13, vacuum gauge; 2, pressure regulating pipeline, 21, first one-way valve, 22, needle valve, 23, pressure reducing valve; 3, Venturi tube; 4, gas sampling bag, 41, gas sampling hose. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments only represent some of the embodiments of the present application, rather than all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use.

[0024] Unless otherwise specifically stated, the relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the various examples disclosed herein are only meant to be illustrative, and not restrictive. It should be understood that the dimensions of the various parts shown in the drawings are not necessarily to scale. Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but should be understood to be part of the specification, where appropriate. In all examples shown and discussed herein, any specific values should be interpreted as merely illustrative, and not as a limitation on the scope of the exemplary embodiments. Thus, other examples of the exemplary embodiments can include different values. It should be noted that like reference numerals and letters refer to like items in the following drawings, and thus, once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0025] In the following examples, the parameters of the components used are shown in Table 1.

[0026] Table 1 Parameters of components used in the embodiments of the present application Assembly Specification parameter Material Venturi tube Inlet diameter 10 mm, throat diameter 5 mm, inlet section length 40 mm 316 stainless steel First one-way valve Model QH21F-16P, pressure resistance 1.6 MPa Stainless steel Needle valve Model J13W-160P, adjustment accuracy ±0.01 L / min Stainless steel Pressure reducing valve Model Y12X-16T, pressure reducing range 0.1~1 MPa Copper alloy Ball valve DN8, opening and closing time ≤2 seconds Stainless steel Second one-way valve Model H12W-16P, reverse sealing pressure ≥0.5 MPa Stainless steel Vacuum gauge Range -0.1~0 MPa, accuracy ±0.01 MPa Stainless steel Inert medium Process nitrogen, pressure 0.4 MPa, flow rate 1.2 m³ / h -

[0027] Embodiment one:

[0028] The embodiment provides a gas sampling and replacement device based on negative pressure suction, which comprises a sampling pipeline 1, a pressure regulating pipeline 2 and a Venturi tube 3. One end of the sampling pipeline 1 is connected to the throat of the Venturi tube 3 through a sealing joint, and the other end is connected with a gas collecting device through a stainless steel sleeve. The pressure regulating pipeline 2 is connected with the inlet section of the Venturi tube 3, is used for introducing inert medium, and is used for regulating the vacuum degree in the sampling pipeline 1 and driving the sampling pipeline 1 to suck sample gas.

[0029] In the embodiment, the inert medium is process nitrogen.

[0030] The pressure regulating pipeline 2 comprises a first one-way valve 21 and a pressure reducing valve 23 which are sequentially passed through after the process nitrogen is introduced. The first one-way valve 21 is used for preventing residual gas in the sampling pipeline 1 and the gas collecting device from mixing into the process nitrogen and polluting the process nitrogen. The pressure reducing valve 23 is used for controlling the pressure of the process nitrogen in the pressure regulating pipeline 2, and the pressure of the process nitrogen is regulated to the minimum through the pressure reducing valve 23, that is, the introduction of the process nitrogen is stopped.

[0031] The sampling pipeline 1 comprises a ball valve 11 and a second one-way valve 12 which are sequentially passed through after sample gas is collected. The ball valve 11 is used for controlling the opening and closing of the sampling pipeline 1, and the second one-way valve 12 is used for preventing the process nitrogen from entering the gas collecting device and polluting the sample gas.

[0032] In use, the first one-way valve 21, the needle valve 22 and the pressure reducing valve 23 are opened, the process nitrogen is introduced, the pressure reducing valve is regulated to 0.4 MPa, the needle valve is regulated to a flow rate of 1.2 m 3 / h, the throat of the Venturi tube forms a negative pressure of -0.05 MPa, and the negative pressure is maintained for 30 seconds, that is, the residual air in the gas collecting device is ≤0.03%. The ball valve 11 and the second one-way valve 12 are opened, the gas pressure in the gas collecting device is greater than the pressure of the throat of the Venturi tube 3, the suction force of the gas based on the negative pressure is generated, the sample gas enters the gas collecting device under the driving of the negative pressure, and 5 L of sample gas can be collected in the gas collecting device in 30 seconds. The vacuum gauge shows that the vacuum is stably kept at -0.04 MPa±0.001 MPa.

[0033] When it is necessary to replace the gas in the gas collecting device, the vacuum degree in the pressure regulating pipeline 2 is cooperatively controlled through the needle valve 22 and the pressure reducing valve 23, the gas in the gas collecting device is discharged through the diffusion section of the Venturi tube 3, that is, the replacement of the gas in the gas collecting device is realized, the replacement is repeated for three times, and the purity of the sample gas in the gas collecting device is ≥99.95%.

[0034] Embodiment two:

[0035] The embodiment is based on the embodiment one, and provides a gas sampling device, and optimizes the structure of the gas sampling replacement device based on negative pressure suction. Figure 1 As shown in the figure, the gas sampling device comprises a gas sampling bag 4 and the gas sampling replacement device based on negative pressure suction as described in the embodiment one.

[0036] The gas sampling bag 4 is a double-gas-port container, comprising a first gas port and a second gas port, the first gas port is connected with the gas sampling replacement device, and the second gas port is connected with a gas sampling port for collecting sample gas through a gas sampling hose 41.

[0037] In the embodiment, the pressure regulating pipeline 2 comprises a first one-way valve 21, a needle valve 22 and a pressure reducing valve 23 in sequence after the process nitrogen gas is introduced, the needle valve 22 is used for controlling the flow of the process nitrogen gas in the pressure regulating pipeline 2, and cooperates with the pressure reducing valve 23 to control the vacuum degree in the pressure regulating pipeline 2.

[0038] Embodiment three:

[0039] The embodiment is based on the embodiment one, and provides a gas sampling device, and optimizes the structure of the gas sampling replacement device based on negative pressure suction. The gas sampling device comprises a gas sampling steel cylinder and the gas sampling replacement device based on negative pressure suction as described in the embodiment one; the gas sampling steel cylinder is a 0.5 L stainless steel gas sampling steel cylinder, the inner wall of which is electrolytic polished, and Ra=0.4 μm.

[0040] In the embodiment, the sampling pipeline 1 comprises a ball valve 11, a second one-way valve 12 and a vacuum gauge 13 in sequence after the sample gas is collected, the vacuum gauge 13 is installed between the second one-way valve 12 and the Venturi tube 3, and is used for displaying the vacuum degree value in the sampling pipeline 1.

[0041] The gas sampling device is used for collecting propylene sample gas (containing 10 ppm propyne), and after three times of replacement, the residual gas in the steel cylinder is less than or equal to 0.06%, the detection deviation of the collected propylene sample gas is 1.8%, and the microanalysis requirement in GB / T 3394-2009 is met.

[0042] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to explain the relative position relationship, movement condition and the like between the components in a certain specific posture. If the specific posture changes, the directional indication also changes accordingly. It is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application.

[0043] In addition, the terms "first", "second", etc. are used only for descriptive purposes and should not be construed as indicating or implying relative importance or an indicated number of technical features. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified and limited, the term "a plurality of" means two or more.

[0044] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0045] The above is only the preferred embodiment of the present application, it should be pointed out that, for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can also be made, these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A gas sampling and displacement device based on negative pressure suction, characterized in that, include: Sampling lines, pressure regulating lines, and venturi tubes; One end of the sampling pipeline is sealed to the throat of the venturi tube, and the other end is connected to the gas collection device. The pressure regulating line is connected to the inlet section of the venturi tube and is used to introduce an inert medium, adjust the vacuum level in the sampling line, and drive the sampling line to draw sample gas at a flow rate of 0.3~2 L / min.

2. The gas sampling and replacement device based on negative pressure suction according to claim 1, characterized in that, The pressure regulating pipeline includes a first check valve, a needle valve, and a pressure reducing valve that the inert medium passes through in sequence after it is introduced. The first check valve has a pressure resistance of ≥1 MPa and is used to prevent residual gas in the sampling pipeline and gas collection device from mixing into the inert medium and contaminating it. The needle valve is used to control the flow rate of the inert medium in the pressure regulating pipeline. The pressure reducing valve has a pressure reduction range of 0.1~1 MPa and is used to control the pressure of the inert medium in the pressure regulating pipeline. The needle valve and the pressure reducing valve work together to adjust the vacuum level in the pressure regulating pipeline to -0.02 MPa ~ -0.08 MPa, with an adjustment response time of ≤3 seconds.

3. The gas sampling and replacement device based on negative pressure suction according to claim 1, characterized in that, The sampling pipeline includes a ball valve and a second check valve that the sample gas passes through sequentially after collection. The ball valve has a diameter of 6~10 mm and is used to control the opening and closing of the sampling pipeline. The opening and closing time is ≤2 seconds. The second check valve is used to prevent inert media from entering the gas collection device and contaminating the sample gas, and the reverse sealing pressure is ≥0.5MPa.

4. The gas sampling and replacement device based on negative pressure suction according to claim 3, characterized in that, The sampling pipeline also includes a vacuum gauge, installed between the second one-way valve and the venturi tube, for real-time display of the vacuum level in the sampling pipeline; the vacuum gauge has a measurement range of -0.1 to 0 MPa and an accuracy of ±0.01 MPa.

5. The gas sampling and replacement device according to claim 1 or 2, characterized in that, The inert medium is process nitrogen, with an oxygen content ≤5 ppm, a dew point ≤-40℃, and a purity ≥99.99%.

6. The gas sampling and replacement device according to claim 1, characterized in that, The diameter of the throat of the Venturi tube is 3-8 mm, and the length of the inlet section of the Venturi tube is 5-8 times the diameter of the throat.

7. A gas sampling device, characterized in that, It includes a gas collection device and a gas sampling and replacement device based on negative pressure suction as described in any one of claims 1-6.

8. The gas sampling device according to claim 7, characterized in that, The gas collection device is a dual-port container with a fixed shape and a volume of 0.5~10 L, including a first port and a second port; the first port is connected to a gas sampling and replacement device, and the second port is connected to the gas sampling port; the working pressure of gas sampling is 0.01~0.5 MPa.

9. The gas sampling device according to claim 8, characterized in that, The first gas port is connected to the gas sampling and replacement device via a φ6~10mm flexible hose, and the second gas port is connected to the gas sampling port via a corrosion-resistant flexible hose.

10. The gas sampling device according to claim 7, characterized in that, The gas collection device includes a gas sampling bag or a gas sampling cylinder; the gas sampling bag is made of polytetrafluoroethylene or aluminum-plastic composite film, with a pressure resistance of 0.2~0.6 MPa; the gas sampling cylinder is made of 316 stainless steel, with an inner wall roughness Ra≤0.8 μm.

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