Liquefied petroleum gas sampling and sample processing method and device

Abstract

The invention discloses a liquefied petroleum gas sampling and sample processing method and device, and the method comprises the following steps: sampling: collecting a preset sampling amount of liquid-phase liquefied petroleum gas from a sample source into a sample cavity, and controlling the pressure of the sample cavity to be consistent with the pressure of the sample source in the sampling process; gasification treatment: treating the liquid-phase liquefied petroleum gas into gas-phase liquefied petroleum gas through volume expansion gasification treatment in the sample cavity. According to the invention, after the liquid-phase liquefied petroleum gas flows into the sample cavity from the sample source, the pressure does not change, so that constant-pressure sampling is realized, and the liquid-phase liquefied petroleum gas is prevented from being partially gasified due to the change of the pressure, so that the representativeness of a sample in the sample cavity can be ensured; furthermore, the liquid-phase liquefied petroleum gas is directly treated into gas-phase liquefied petroleum gas through volume expansion gasification treatment in the sample cavity, so that the component content of the liquefied petroleum gas in the sample cavity is kept unchanged, and the accuracy of an analysis result is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of gas sampling, and in particular to a method and a device for liquefied petroleum gas sampling and sample processing. Background Art

[0002] This section is intended to provide a background or context to the embodiments of the invention recited in the claims. No description herein is admitted to be prior art by inclusion in this section.

[0003] Liquefied petroleum gas (LPG) is a basic energy source for industrial production and residents' lives, and occupies a very important position in the energy structure. LPG is a low-carbon hydrocarbon mixture, the main components of which are C3-C5 hydrocarbons. The main components of LPG obtained from refinery gas include propane, propylene, butane, butene, and also contain a small amount of pentane, pentene and trace sulfur-containing compound impurities. According to the requirements of liquefied petroleum gas, the sum of C3 and C4 hydrocarbon components in LPG should account for more than 95% of the total volume fraction, and the sum of C5 and above hydrocarbon components should be less than 3% of the total component volume fraction. When the content of heavy hydrocarbon components exceeds the standard, it will not only cause incomplete combustion, but also produce a large amount of residual liquid. These residual liquids are difficult to gasify in the cylinder, and they are very easy to volatilize in the atmosphere when poured out, which is easy to cause safety hazards.

[0004] The accuracy of the analysis results directly affects the production quality of LPG and the quantity and quality judgment of LPG delivery in LPG trade. The representativeness of the sample directly affects the accuracy of the composition analysis results, so it is extremely important to obtain representative samples.

[0005] In the prior art, a single-valve or multi-valve sampler is used to sample LPG, and the general steps include:

[0006] (1) First open the inlet valve and outlet valve at both ends of the sampler, then slowly open the sample source valve connected to the sample source to allow the sample to flush the sampler. Determine the flushing time based on the capacity of the sampler. The flushing time is generally 0.5 min to 1.5 min. After the flushing time meets the requirements, close the inlet valve of the sampler and turn the outlet valve downward to drain the flushed sample in the sampler. Repeat this operation three times, then turn the outlet valve upward and close it to prepare for sampling.

[0007] (2) First open the inlet valve of the sampler. When the sampler has been partially filled with liquid sample, slowly open the outlet valve of the sampler to facilitate the discharge of the vaporized sample. When liquid sample appears at the outlet valve, close the outlet valve first, and then close the inlet valve and sample source valve of the sampler in turn. Loosen the sampling pipeline interface slightly, and after the pressure in the sampling pipeline is released, remove the sampler and pipeline.

[0008] (3) Open the valve at one end of the sampler, release about 20% of the sample, then close the valve and tighten the valves at both ends again to prevent leakage.

[0009] During the LPG sampling process, due to changes in temperature and pressure, the sample obtained may be partially vaporized, causing the sample to lose its representativeness.

[0010] In addition, after LPG sampling, the sample needs to be gasified before sampling and analysis. The gasification process is generally handled by a constant temperature water bath. The method and principle are that the liquid LPG sample enters the coil of the gasifier, and then is heated by the hot water outside the coil to force gasification. After gasification, the gasified gas is output downstream. During the gasification process, since the light components will be gasified first and the heavy components will be gasified later, there will be differences between the gas components entering the gas chromatograph and the liquid LPG sample source, causing distortion of the analysis results. Summary of the invention

[0011] The object of the present invention is to provide a method and device for sampling and processing liquefied petroleum gas, so as to solve the technical problems that part of the sample obtained from the liquid phase LPG sample is vaporized due to changes in temperature and pressure during the sampling process, resulting in the sample losing its representativeness, and the light component of the liquid phase LPG sample is vaporized first and the heavy component is vaporized later during the gasification treatment process, resulting in errors in the analysis results.

[0012] The above-mentioned purpose of the present invention can be achieved by adopting the following technical solutions:

[0013] The present invention provides a method for sampling and processing liquefied petroleum gas, comprising the following steps: sampling: collecting a preset sampling amount of liquid-phase liquefied petroleum gas from a sample source into a sample cavity, and controlling the pressure of the sample cavity to be consistent with the pressure of the sample source during the sampling process; gasification processing: in the sample cavity, processing the liquid-phase liquefied petroleum gas into gas-phase liquefied petroleum gas through volume expansion gasification processing.

[0014] In an embodiment of the present invention, before the sampling step, it also includes: a piston is sealingly and slidingly arranged in an inner cavity, thereby isolating the sample cavity in the inner cavity; the sampling step includes: connecting the sample cavity with the sample source, so that the liquid phase liquefied petroleum gas slowly flows from the sample source into the sample cavity, and according to the pressure of the sample source, the piston is controlled to slide in the inner cavity, so that the volume of the sample cavity is adaptively increased and the pressure of the sample cavity is consistent with the pressure of the sample source; until the liquid phase liquefied petroleum gas in the sample cavity reaches the preset sampling volume, the sample cavity and the sample source are disconnected.

[0015] In an embodiment of the present invention, before the sampling step, it also includes: dividing the inner cavity into a sample cavity and a pressure-stabilizing cavity by the piston; wherein the pressure-stabilizing cavity and the sample cavity are located on both sides of the piston; connecting the pressure-stabilizing cavity with a pressure-stabilizing gas source so that the pressure-stabilizing gas flows from the pressure-stabilizing gas source into the pressure-stabilizing cavity, thereby pushing the piston to move toward the sample cavity; until the volume of the sample cavity is minimized, disconnecting the pressure-stabilizing cavity from the pressure-stabilizing gas source.

[0016] In an embodiment of the present invention, the sampling step includes: controlling the pressure of the pressure-stabilizing chamber to be equal to the pressure of the sample source; connecting the sample chamber with the sample source so that the liquid phase liquefied petroleum gas slowly flows from the sample source into the sample chamber, and slowly discharging the pressure-stabilizing gas in the pressure-stabilizing chamber, so that the piston is pushed to slowly slide toward one side of the pressure-stabilizing chamber under the action of the pressure difference between the pressure-stabilizing chamber and the sample chamber, and the pressure of the sample chamber is consistent with the pressure of the sample source; until the liquid phase liquefied petroleum gas in the sample chamber reaches the preset sampling volume, the sample chamber and the sample source are disconnected.

[0017] In an embodiment of the present invention, before the sampling step, the steps further include: connecting the sample chamber with a vacuum pumping device; starting the vacuum pumping device to vacuum the sample chamber; and disconnecting the sample chamber from the vacuum pumping device until the sample chamber reaches a preset vacuum degree.

[0018] In an embodiment of the present invention, before the sampling step, the preset sampling volume is determined based on the phase diagram, the maximum volume of the sample chamber and the pressure of the sample source; the gasification processing step includes: completely discharging the pressure-stabilizing gas in the pressure-stabilizing chamber, so that the piston moves toward the pressure-stabilizing chamber to maximize the volume of the sample chamber, and the liquid phase of liquefied petroleum gas is processed into the gas phase of liquefied petroleum gas in the sample chamber.

[0019] In an embodiment of the present invention, the gasification step further includes: gas homogenization treatment: uniformly distributing the gaseous liquefied petroleum gas in the sample cavity to various regions in the sample cavity.

[0020] In an embodiment of the present invention, the gas homogenization step includes: oscillating the sample chamber for a preset time so that the gas phase liquefied petroleum gas inside is evenly distributed in various areas in the sample chamber.

[0021] In an embodiment of the present invention, a device for sampling and processing liquefied petroleum gas includes: a device body having an inner cavity; a piston sealingly and slidably disposed in the inner cavity and separating a sample cavity from the inner cavity; and a sampling valve connected to the sample cavity.

[0022] In an embodiment of the present invention, the piston further separates a pressure-stabilizing chamber from the inner chamber, the pressure-stabilizing chamber and the sample chamber are located on both sides of the piston, and the device further comprises a gas valve, which is connected to the pressure-stabilizing chamber.

[0023] In an embodiment of the present invention, the device further comprises a pressure-stabilizing exhaust valve, and the pressure-stabilizing exhaust valve is connected to the pressure-stabilizing chamber.

[0024] In an embodiment of the present invention, the device further comprises a sample end exhaust valve, and the sample end exhaust valve is communicated with the sample chamber.

[0025] In an embodiment of the present invention, the device body is a transparent visible structure, and a capacity identification structure is provided on the device body.

[0026] The characteristics and advantages of the present invention are:

[0027] The method for sampling and processing liquefied petroleum gas of the present invention controls the pressure of the sample chamber to be consistent with the pressure of the sample source during the sampling process, so that the pressure of the liquid phase liquefied petroleum gas does not change after flowing from the sample source into the sample chamber, thereby realizing constant pressure sampling, avoiding partial gasification of the liquid phase liquefied petroleum gas due to pressure changes, thereby ensuring the representativeness of the sample in the sample chamber, and then directly processing the liquid phase liquefied petroleum gas into gas phase liquefied petroleum gas through volume expansion gasification treatment in the sample chamber. According to the principle of material balance, it can be known that the component content of the gas phase liquefied petroleum gas in the sample chamber and the liquid phase liquefied petroleum gas before the phase change remains unchanged, thereby ensuring the accuracy of the analysis result.

[0028] The device for sampling and processing liquefied petroleum gas of the present invention provides a piston in an inner cavity for sealing and sliding, thereby separating a sample cavity in the inner cavity through the piston, and providing a sampling valve to communicate with the sample cavity, and then sampling is performed by opening the sampling valve to connect the sample cavity with a sample source. As liquid-phase liquefied petroleum gas flows from the sample source into the sample cavity, the size of the sample cavity can be controlled by controlling the sliding of the piston, thereby controlling the pressure of the sample cavity to be consistent with the pressure of the sample source. When the liquid-phase liquefied petroleum gas in the sample cavity reaches a preset sampling amount, the sampling valve can be closed, so that the sample cavity forms a closed cavity, and then the volume expansion and gasification treatment of the liquid-phase liquefied petroleum gas is performed in the sample cavity, thereby ensuring the representativeness of the sample in the sample cavity and facilitating the improvement of the accuracy of the analysis result. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 The figure is a schematic diagram of the process of liquefied petroleum gas sampling and sample processing in the present invention.

[0031] Figure 2 The schematic diagram of the structure of the device for sampling and processing liquefied petroleum gas before sampling in the present invention.

[0032] Figure 3 The schematic diagram is a structural diagram of the device for sampling and processing liquefied petroleum gas after sampling in the present invention.

[0033] In the figure:

[0034] 11. Device body; 12. Piston; 13. Sample chamber; 14. Pressure-stabilizing chamber; 15. Gas valve; 16. Sampling valve; 17. Pressure-stabilizing exhaust valve; 18. Sample end exhaust valve. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Implementation Method 1

[0037] like Figure 1 As shown, the present invention provides a method for liquefied petroleum gas sampling and sample processing, comprising the following steps:

[0038] Step S1, sampling: collecting a preset sampling amount of liquid-phase liquefied petroleum gas from a sample source into a sample chamber 13, and controlling the pressure of the sample chamber 13 to be consistent with the pressure of the sample source during the sampling process;

[0039] Step S2, gasification treatment: in the sample chamber 13, the liquid phase liquefied petroleum gas is processed into gas phase liquefied petroleum gas through volume expansion gasification treatment.

[0040] The method for sampling and processing liquefied petroleum gas of the present invention controls the pressure of the sample chamber 13 to be consistent with the pressure of the sample source during the sampling process, so that the pressure of the liquid phase liquefied petroleum gas does not change after flowing from the sample source into the sample chamber 13, thereby realizing constant pressure sampling, avoiding partial gasification of the liquid phase liquefied petroleum gas due to pressure changes, thereby ensuring the representativeness of the sample in the sample chamber 13, and then directly processing the liquid phase liquefied petroleum gas into gas phase liquefied petroleum gas through volume expansion gasification treatment in the sample chamber 13. According to the principle of material balance, it can be known that the component content of the gas phase liquefied petroleum gas in the sample chamber 13 and the liquid phase liquefied petroleum gas before the phase change remains unchanged, thereby ensuring the accuracy of the analysis result.

[0041] Specifically, the pressure of the liquid phase liquefied petroleum gas after flowing into the sample chamber 13 is related to the size of the sample chamber 13. Therefore, during the sampling process, the size of the sample chamber 13 is adaptively controlled according to the pressure of the sample source, so that the pressure of the sample chamber 13 can be controlled to be equal to the pressure of the sample source.

[0042] Combination Figure 2 and Figure 3 As shown, in some embodiments of the present invention, before the sampling step S1, it also includes: a piston 12 is provided in an inner cavity for sealing and sliding, so as to separate a sample cavity 13 in the inner cavity. When the piston 12 slides toward the side close to the sample cavity 13, the volume of the sample cavity 13 decreases; when the piston 12 slides toward the side away from the sample cavity 13, the volume of the sample cavity 13 increases. Therefore, by controlling the sliding of the piston 12, the size of the sample cavity 13 can be controlled, so that the pressure of the sample cavity 13 can be controlled to be equal to the pressure of the sample source.

[0043] Specifically, the sampling step S1 includes: connecting the sample chamber 13 with the sample source, allowing the liquid phase of liquefied petroleum gas to slowly flow from the sample source into the sample chamber 13, and controlling the piston 12 to slide in the inner chamber according to the pressure of the sample source, so that the volume of the sample chamber 13 is adaptively increased and the pressure of the sample chamber 13 is equal to the pressure of the sample source; until the liquid phase of the liquefied petroleum gas in the sample chamber 13 reaches a preset sampling volume, disconnecting the sample chamber 13 from the sample source.

[0044] Combination Figure 2 and Figure 3As shown, in the embodiment of the present invention, the inner cavity is arranged in a device body 11. The sample cavity 13 is connected with a sampling valve 16. By controlling the opening and closing of the sampling valve 16, the connection and disconnection between the sample cavity 13 and the sample source can be controlled, and by controlling the opening of the sampling valve 16, the speed of the liquid phase liquefied petroleum gas flowing into the sample cavity 13 can be controlled. The device body 11 can be a transparent visual structure, so as to observe the position of the piston 12 in the sample cavity 13. In addition, a capacity identification structure can be arranged on the device body 11 to determine the capacity of the liquefied petroleum gas in the sample cavity 13 according to the capacity identification structure. Specifically, the maximum volume of the sample cavity 13 can be 1L, that is, the volume of the entire sample cavity 13 after sampling and gasification treatment is completed is 1L, and the capacity identification structure includes a plurality of capacity scales that are arranged at intervals and gradually increase from the minimum volume of the sample cavity to the maximum volume of the sample cavity 13, for example: "0.01L", "0.02L", "0.03L", "0.04L", "0.05L", etc.

[0045] Combination Figure 2 and Figure 3 As shown, in some embodiments of the present invention, before the sampling step S1, the method further includes: dividing the inner cavity into a sample cavity 13 and a pressure-stabilizing cavity 14 by a piston 12; wherein the pressure-stabilizing cavity 14 and the sample cavity 13 are located on both sides of the piston 12; connecting the pressure-stabilizing cavity 14 with a pressure-stabilizing gas source, so that the pressure-stabilizing gas flows from the pressure-stabilizing gas source into the pressure-stabilizing cavity 14, thereby pushing the piston 12 to move toward the sample cavity 13; until the volume of the sample cavity 13 is minimized, disconnecting the pressure-stabilizing cavity 14 from the pressure-stabilizing gas source. By injecting the pressure-stabilizing gas into the pressure-stabilizing cavity 14, the pressure-stabilizing gas is used to push the piston 12 to slide toward the side close to the sample cavity 13, thereby discharging the gas in the sample cavity 13 and minimizing the volume of the sample cavity 13, and then controlling the piston 12 to slide toward the side away from the sample cavity 13 during the sampling process, so that the sample cavity 13 contains more liquid-phase liquefied petroleum gas, and at the same time, the pressure of the sample cavity 13 is equal to the pressure of the sample source, and it can prevent the gasified liquefied petroleum gas from introducing other gases to affect the accuracy of the analysis result. The pressure-stabilizing gas is an inert gas, such as nitrogen.

[0046] Specifically, the pressure-stabilizing chamber 14 is connected to a gas valve 15, and the connection and disconnection between the pressure-stabilizing chamber 14 and the pressure-stabilizing gas source can be controlled by controlling the opening and closing of the gas valve 15. The device body 11 includes a shell and a first delivery pipe and a second delivery pipe connected to the shell, the sampling valve 16 is installed on the first delivery pipe, and the gas valve 15 is installed on the second delivery pipe. The shell is generally a columnar shell, such as a cylindrical or multi-prism shell. The shell has a first end and a second end relative to each other in its axial direction, and the piston 12 is sealed and slidably matched with the inner side surface of the shell, and the piston 12 can slide between the inner end surface of the first end of the shell and the inner end surface of the second end of the shell. The sample chamber 13 includes a spacing space between the piston 12 and the inner end surface of the first end of the shell, and the pressure-stabilizing chamber 14 includes a spacing space between the piston 12 and the inner end surface of the second end of the shell.

[0047] Combination Figure 2 and Figure 3 As shown, further, before the sampling step S1, it also includes: connecting the sample chamber 13 with the vacuum pumping device; starting the vacuum pumping device to vacuum the sample chamber 13; until the sample chamber 13 reaches a preset vacuum degree, disconnecting the sample chamber 13 from the vacuum pumping device. The sample chamber 13 is vacuumed by the vacuum pumping device, so that the gas in the sample chamber 13 is discharged, further preventing the gasified liquefied petroleum gas from introducing other gases and affecting the accuracy of the analysis result.

[0048] Specifically, the sample chamber 13 is connected to a sample end exhaust valve 18, and the sample end exhaust valve 18 can be connected to a vacuum pumping device, and then the connection between the vacuum pumping device and the sample chamber 13 can be controlled by controlling the opening and closing of the sample end exhaust valve 18, so as to vacuum the sample chamber 13. After the vacuum pumping device vacuums the sample chamber 13, it can ensure that the piston 12 is in contact with the inner end surface of the first end of the housing and completely extract the residual gas in the first delivery pipe.

[0049] Combination Figure 2 and Figure 3 As shown, in order to achieve more accurate and convenient control of the pressure of the sample chamber 13 during the sampling process and ensure that the pressure of the sample chamber 13 is always consistent with the pressure of the sample source during the sampling process, in an embodiment of the present invention, the sampling step S1 includes: controlling the pressure of the pressure-stabilizing chamber 14 to be equal to the pressure of the sample source; connecting the sample chamber 13 with the sample source, so that the liquid phase of liquefied petroleum gas slowly flows from the sample source into the sample chamber 13, and the pressure-stabilizing gas in the pressure-stabilizing chamber 14 is slowly discharged, so that the piston 12 slowly slides toward one side of the pressure-stabilizing chamber 14 under the action of the pressure difference between the sample chamber 13 and the pressure-stabilizing chamber 14, and the pressure of the sample chamber 13 is consistent with the pressure of the sample source; until the liquid phase of the liquefied petroleum gas in the sample chamber 13 reaches a preset sampling volume, the sample chamber 13 is disconnected from the sample source.

[0050] Before the sample chamber 13 is connected to the sample source, the pressure in the pressure-stabilizing chamber 14 is equal to the pressure in the sample source. After the sample chamber 13 is connected to the sample source, the liquid liquefied petroleum gas flows into the sample chamber 13. Since the pressures on both sides of the piston are equal, the piston cannot move. As a result, the gas in the pressure-stabilizing chamber 14 is slowly discharged, so that the pressure in the pressure-stabilizing chamber 14 is always slightly lower than the pressure in the sample chamber 13, and the pressure in the sample chamber 13 is always consistent with the pressure in the sample source, and the piston 12 slowly moves toward one side of the pressure-stabilizing chamber 14.

[0051] Specifically, the injection amount of the sample chamber 13 is controlled by controlling the opening of the sampling valve 16. The pressure-stabilizing chamber 14 is connected to the pressure-stabilizing exhaust valve 17. By controlling the opening and closing of the pressure-stabilizing exhaust valve 17, the pressure-stabilizing gas in the pressure-stabilizing chamber 14 can be discharged, and by controlling the opening of the pressure-stabilizing exhaust valve 17, the exhaust amount of the pressure-stabilizing chamber 14 can be controlled. By controlling the exhaust amount of the pressure-stabilizing chamber 14 and the injection amount of the sample chamber 13, the pressure of the pressure-stabilizing chamber 14 can be controlled to be always slightly lower than the pressure of the sample chamber 13 during the sampling process, so that the piston 12 slides slowly toward one side of the pressure-stabilizing chamber 14, thereby making the pressure of the sample chamber 13 equal to the pressure of the sample source. Optionally, before the sample chamber 13 is connected to the sample source, the pressure of the pressure-stabilizing chamber 14 may be slightly greater than or slightly lower than the pressure of the sample source, for example, within a preset pressure difference range. Then, after the sample chamber 13 is connected to the sample source, the exhaust volume of the pressure-stabilizing chamber is controlled by controlling the opening of the pressure-stabilizing exhaust valve 17, and the injection volume of the sample chamber 13 is controlled by controlling the sampling valve 16, so that the pressure of the pressure-stabilizing chamber 14 is controlled to be slightly lower than the pressure of the sample chamber 13, and the pressure of the sample chamber 13 is consistent with the pressure of the sample source.

[0052] like Figure 3 As shown, in the embodiment of the present invention, before the sampling step S1, the preset sampling volume is determined according to the phase diagram, the maximum volume of the sample chamber and the pressure of the sample source; the gasification treatment step S2 includes: the pressure-stabilizing gas in the pressure-stabilizing chamber 14 is completely discharged, so that the piston 12 moves toward the pressure-stabilizing chamber 14 to maximize the volume of the sample chamber 13, and the liquid phase liquefied petroleum gas is processed into gas phase liquefied petroleum gas in the sample chamber 13. After the sampling is completed, the pressure of the pressure-stabilizing chamber 14 is released to the atmospheric pressure state by completely discharging the pressure-stabilizing gas in the pressure-stabilizing chamber 14. Since the sample chamber 13 has a high pressure, the piston 12 slides to the maximum volume of the sample chamber 13 under the pressure of the sample chamber 13, that is, the piston 12 fits the inner end surface of the second end of the housing. Among them, the phase diagram is a gas-liquid phase equilibrium phase diagram of liquefied petroleum gas. According to the phase diagram, it is possible to judge whether the liquid phase liquefied petroleum gas in the sample chamber 13 can be gasified due to the change in pressure after the volume of the sample chamber 13 increases from the preset sampling volume to its maximum volume, thereby processing the liquid phase liquefied petroleum gas into gasified liquefied petroleum gas.

[0053] like Figure 1As shown, in an embodiment of the present invention, the gasification treatment step S2 further includes: step S3, gas homogenization treatment: uniformly distributing the gas phase liquefied petroleum gas in the sample chamber 13 in various areas in the sample chamber 13. By subjecting the gas phase liquefied petroleum gas to gas homogenization treatment, it is avoided that the gas components of the gas phase liquefied petroleum gas are unevenly distributed due to different densities. Therefore, when the sampling valve 16 connects the sample chamber 13 with the gas analysis instrument (such as a gas chromatograph), it can ensure that the components of the sample gas entering the gas analysis instrument are consistent with the components of the sample source. Specifically, the gas homogenization treatment step includes: oscillating the sample chamber 13 for a preset time so that the gas phase liquefied petroleum gas inside is evenly distributed in various areas in the sample chamber 13.

[0054] Specifically, the sample end exhaust valve 18 can also be connected to a gas analysis instrument, so that the liquefied petroleum gas after gasification in the sample cavity 13 enters the gas analysis instrument for analysis.

[0055] In addition, flushing is also included before the sampling step S1, in which a certain amount of liquid-phase liquefied petroleum gas is made to flow into the sample chamber 13 in the same manner, and then gasified into gas-phase liquefied petroleum gas and subjected to gas homogenization, and then all the gas-phase liquefied petroleum gas in the sample chamber 13 is discharged, and this is repeated multiple times to achieve flushing of the sample chamber 13, thereby facilitating the improvement of the accuracy of the analysis results. Specifically, the sample end exhaust valve 18 can also be connected to a sample collection device to collect the gas-phase liquefied petroleum gas discharged during the flushing process into the sample collection device.

[0056] Implementation Method 2

[0057] like Figure 2 and Figure 3 As shown, the present invention also provides a device for liquefied petroleum gas sampling and sample processing. Since the principle of solving the problem by the device is similar to the method for liquefied petroleum gas sampling and sample processing in Implementation Method 1, the implementation of the device can refer to the implementation of the method for liquefied petroleum gas sampling and sample processing in Implementation Method 1, and the repeated parts will not be repeated.

[0058] like Figure 2 and Figure 3 As shown, the device for sampling and processing liquefied petroleum gas of the present invention comprises: a device body 11 having an inner cavity; a piston 12 sealingly and slidably disposed in the inner cavity and separating a sample cavity 13 from the inner cavity; and a sampling valve 16 communicating with the sample cavity 13.

[0059] The device for sampling and processing liquefied petroleum gas of the present invention provides a piston 12 in an inner cavity for sealing and sliding, thereby separating a sample cavity 13 in the inner cavity through the piston 12, and providing a sampling valve 16 to communicate with the sample cavity 13, and then the sampling valve 16 is opened to connect the sample cavity 13 with a sample source for sampling. As the liquid phase liquefied petroleum gas flows from the sample source into the sample cavity 13, the size of the sample cavity 13 can be controlled by controlling the sliding of the piston 12, thereby controlling the pressure of the sample cavity 13 to be consistent with the pressure of the sample source. When the liquid phase liquefied petroleum gas in the sample cavity 13 reaches a preset sampling amount, the sampling valve 16 can be closed, so that the sample cavity 13 forms a closed cavity, and then the volume expansion and gasification treatment of the liquid phase liquefied petroleum gas is carried out in the sample cavity 13, thereby ensuring the representativeness of the sample in the sample cavity 13 and facilitating the improvement of the accuracy of the analysis result.

[0060] like Figure 2 and Figure 3 As shown, in the embodiment of the present invention, the piston 12 also separates a pressure stabilizing chamber 14 in the inner cavity, and the pressure stabilizing chamber 14 and the sample chamber 13 are located on both sides of the piston 12. The device also includes a gas valve 15, and the gas valve 15 is connected to the pressure stabilizing chamber 14. Specifically, the device also includes a pressure stabilizing exhaust valve 17, and the pressure stabilizing exhaust valve 17 is connected to the pressure stabilizing chamber 14. In addition, the device also includes a sample end exhaust valve 18, and the sample end exhaust valve 18 is connected to the sample chamber 13. Figure 2 and Figure 3 As shown, in the embodiment of the present invention, the device body 11 is a transparent visible structure, and a capacity identification structure is provided on the device body 11.

[0061] In order to more clearly understand and implement the method and device for liquefied petroleum gas sampling and sample processing of the present invention, some specific embodiments of the present invention and comparative examples of the prior art are provided below for illustration:

[0062] Five experimental samples were obtained and processed by the method of the present invention and five identical devices:

[0063] The pressure-stabilizing gas source is a high-pressure nitrogen cylinder, whose pressure is greater than 4Mpa; the pressure of the liquefied petroleum gas sample source is 4MPa.

[0064] Device: The maximum volume of the sample chamber 13 can be 1L, that is, the volume of the entire sample chamber 13 after sampling and gasification treatment is completed is 1L, and the capacity identification structure includes a plurality of capacity scales that are spaced and gradually increased from the minimum volume of the sample area cavity to the maximum volume of the sample chamber 13, for example: "0.01L", "0.02L", "0.03L", "0.04L", "0.05L", etc.

[0065] The specific operation process is as follows:

[0066] Place the cleaned liquefied petroleum gas sampling and sample processing device stably in the designated position, connect the output end of the high-pressure nitrogen bottle to the gas valve 15, adjust the pressure of the input high-pressure nitrogen to 3.95MPa, push the piston 12 to fit the inner end surface of the first end of the shell (also called Figure 1 The right end of the housing shown in the figure) is used to discharge the gas in the sample chamber 13, the gas valve 15 is closed, and the high-pressure nitrogen bottle is disconnected from the gas valve 15;

[0067] The sampling valve 16 is connected to the sample source, and the sampling valve 16 and the pressure-stabilizing exhaust valve 17 are slightly opened, so that the liquid phase liquefied petroleum gas in the sample source slowly flows into the sample chamber 13, and the gas in the pressure-stabilizing chamber 14 is slowly discharged, so that the pressure of the pressure-stabilizing chamber 14 is always maintained at 3.95MPa, and the pressure of the sample chamber 13 is always maintained at 4MPa. When the right side of the piston 12 coincides with the volume scale of the preset sampling amount, the sampling valve 16 is closed to complete the sampling; wherein, the sampling amounts of the liquid phase liquefied petroleum gas in the five devices are respectively: sample one: 0.05L; sample two: 0.05L; sample three: 0.05L; sample four: 0.03L; sample five: 0.05L;

[0068] The pressure stabilizing exhaust valve 17 is opened to release the high-pressure nitrogen in the pressure stabilizing chamber 14 to the atmospheric pressure state. Due to the pressure difference between the pressure stabilizing chamber 14 and the sample chamber 13, the liquid phase liquefied petroleum gas in the sample chamber 13 pushes the piston 12 to fit with the inner end surface of the second end of the shell (also known as the second end surface of the second end ... Figure 1 The left end of the housing shown in the figure), therefore, the volume of the sample chamber 13 changes from the preset sampling volume to 1L, and the liquid phase of the liquefied petroleum gas changes from the liquid state to the gaseous state, completing the gasification of the liquefied petroleum gas;

[0069] The device after the gasification treatment is left to stand, and a mark is made on the device. Before the gas chromatography analysis is performed, the device is shaken to perform a gas homogenization treatment on the gas phase liquefied petroleum gas in the sample chamber 13 .

[0070] For gas chromatography analysis of liquefied petroleum gas samples:

[0071] Gas chromatography analysis of liquefied petroleum gas is an existing technology, mainly based on the requirements of the national standard NB / SH / T 0230-2019 "Gas chromatography method for determination of liquefied petroleum gas composition". The main steps include analyzing calibration samples (i.e., standard substances) to determine the relative correction factors of each component; blank sample analysis to ensure that there is no residue and contamination in the system; liquefied petroleum gas sample analysis. Among them, the analysis of calibration samples (i.e., standard substances) and blank sample analysis will not be repeated, and the analysis methods are all routinely operated according to standard operations. Therefore, the following is a brief description of the analysis of the hydrocarbon components of the sample.

[0072] Gas analysis instrument: gas chromatograph;

[0073] Gas chromatograph method conditions: Chromatographic column: Al 2 O 3 Chromatographic column; Detector: FID detector; Carrier gas: helium; Inlet temperature: 200℃;

[0074] The sampling valves 16 of the five devices after the gas homogenization treatment are directly connected to the gas chromatograph respectively, and the gas chromatograph is started to perform sample injection analysis.

[0075] After the sample analysis is completed, the peak area of ​​each component in the sample is obtained, and the volume fraction V of each hydrocarbon component in the sample is calculated according to the following formula using the correction normalization method: Ti :

[0076]

[0077] Where: V Ti ——Volume fraction of hydrocarbon component i in the liquefied petroleum gas sample, %; f vi ——Correction factor of hydrocarbon component i in liquefied petroleum gas sample (the correction factor calculated from the calibration sample); A Ti ——Peak area of ​​hydrocarbon component i in liquefied petroleum gas sample; The sum of the products of the correction factors and peak areas of the n hydrocarbon components to be measured.

[0078] After analysis and calculation, the analysis results (volume fractions, %) of the five samples obtained by the five sampling devices are shown in the following table:

[0079] Components Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Ethane 0.140 0.151 0.150 0.146 0.144 Propane 41.246 41.607 41.533 41.145 40.973 Propylene 0.015 0.016 0.012 0.013 0.010 Isobutane 29.444 29.619 29.700 29.706 29.779 n-Butane 28.993 28.576 28.473 28.851 28.950 Trans-2-Butene 0.017 0.016 0.016 0.016 0.016 n-Butene 0.004 0.004 0.004 0.004 0.004 Isobutylene 0.095 0.078 0.080 0.084 0.087 Cis-2-Butene 0.012 0.011 0.010 0.010 0.010 Isopentane 0.005 0.004 0.004 0.004 0.004 n-Pentane 0.029 0.019 0.019 0.021 0.022 1,3-Butadiene 0.000 0.000 0.000 0.000 0.000 n-pentene 0.000 0.000 0.000 0.000 0.000 n-Hexane 0.000 0.000 0.000 0.000 0.000 total 100.000 100.100 100.000 100.000 100.000

[0080] The uncertainty of measurement is determined by the range method. It should be noted that among the hydrocarbon components of liquefied petroleum gas, propane, isobutane and n-butane are the most abundant, while the contents of other components are relatively low. If the contents are too low, the uncertainty itself will be high. Therefore, the three components with the largest contents are selected for measurement uncertainty analysis.

[0081] Select the single measured value x of each of the three components of propane, isobutane and n-butane k , and then calculate the experimental standard deviation s(x k ),

[0082] Among them, R is the range and C is the range coefficient.

[0083] Uncertainty

[0084] The range coefficients are shown in the following table:

[0085] n 2 3 4 5 6 7 8 9 C 1.13 1.69 2.06 2.33 2.53 2.70 2.85 2.97

[0086] According to the calculation method of the uncertainty u(x) above, the uncertainty of the gas chromatography analysis result of the method of the present invention is calculated as shown in the following table:

[0087]

[0088] Five comparative samples were obtained and processed by sampling using the prior art:

[0089] The pressure of the sample source of liquefied petroleum gas is also 4MPa.

[0090] The sampling method adopts the existing method of directly injecting the liquid phase liquefied petroleum gas in the sample source into five sampling cylinders, that is, the sampling cylinders have a moving pressure;

[0091] Among them, the five comparison samples collected from five sampling cylinders are comparison sample one: 0.2L; comparison sample two: 0.25L; comparison sample three: 0.2L; comparison sample four: 0.25L, and comparison sample five: 0.2L.

[0092] Connect the liquid phase liquefied petroleum gas sample to be tested to the liquid valve or flash evaporator for sample processing, adjust the flow rate, ensure that the sample reaches a uniform gasification state for about 1 minute, and then start the gas chromatograph for sample analysis.

[0093] After analysis and calculation, the analysis results (volume fractions, %) of the five comparative samples are shown in the following table:

[0094] Components Comparative sample 1 Comparative sample 2 Comparative sample 3 Comparative sample 4 Comparative sample 5 Ethane 0.140 0.151 0.150 0.146 0.144 Propane 39.446 41.907 41.733 41.145 40.673 Propylene 0.015 0.016 0.011 0.013 0.010 Isobutane 30.244 29.419 29.500 29.706 29.879 n-Butane 29.993 28.376 28.473 28.850 29.150 Trans-2-Butene 0.017 0.016 0.016 0.016 0.016 n-Butene 0.004 0.004 0.004 0.004 0.004 Isobutylene 0.095 0.078 0.080 0.084 0.087 Cis-2-Butene 0.012 0.011 0.010 0.010 0.010 Isopentane 0.005 0.004 0.004 0.004 0.004 n-Pentane 0.029 0.019 0.019 0.021 0.022 1,3-Butadiene 0.000 0.000 0.000 0.000 0.000 n-pentene 0.000 0.000 0.000 0.000 0.000 n-Hexane 0.000 0.000 0.000 0.000 0.000 total 100.000 100.000 100.000 100.000 100.000

[0095] According to the calculation method of the uncertainty u(x) mentioned above, the uncertainty of the gas chromatography analysis results of the prior art is calculated as shown in the following table:

[0096]

[0097] The uncertainty comparison of the gas chromatography analysis results obtained by the present invention and the prior art is shown in the following table:

[0098] Components Prior art methods Method of the present invention Improvement (percentage) Propane 0.473％ 0.159％ 66.38％ Isobutane 0.158％ 0.064％ 59.49％ n-Butane 0.310％ 0.100％ 67.74％

[0099] In summary, compared with the prior art, the method and device of the present invention for sampling and gasification of liquefied petroleum gas has a reduction in uncertainty of 59% to 67% in the content results of the main components of the gas phase liquefied petroleum gas obtained after gas chromatography analysis, thereby avoiding distortion of the analysis results, ensuring the representativeness of the sample, and greatly improving the accuracy of gas chromatography analysis of liquefied petroleum gas.

[0100] In the description of this specification, it should be understood that the terms "center", "length", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "inside", "outside", "peripheral", "circumferential" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing this specification and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this specification.

[0101] In the description of this specification, “plurality” means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0102] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0103] The terms used in this specification are those general terms currently widely used in the art in consideration of the functions of the present disclosure, but these terms may vary according to the intention of a person of ordinary skill in the art, precedents, or new technologies in the art. In addition, specific terms may be selected by the applicant, and in this case, their detailed meanings will be described in the detailed description of the present disclosure. Therefore, the terms used in the specification should not be understood as simple names, but rather as an overall description based on the meaning of the terms and the present disclosure.

[0104] Flowcharts or text are used in this specification to illustrate the operation steps performed according to the embodiments of the present application. It should be understood that the operation steps in the embodiments of the present application are not necessarily performed accurately in the order of recording. On the contrary, various steps can be processed in reverse order or simultaneously as needed. At the same time, other operations can also be added to these processes, or one or more operations can be removed from these processes.

[0105] The above are only several embodiments of the present invention. Those skilled in the art may make various changes or modifications to the embodiments of the present invention based on the contents disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. A method for sampling and processing liquefied petroleum gas, It is characterized in that The following steps are involved: Sampling: collecting a preset sampling amount of liquid-phase liquefied petroleum gas from a sample source into a sample chamber, and controlling the pressure of the sample chamber to be consistent with the pressure of the sample source during the sampling process; Gasification treatment: In the sample chamber, the liquid phase liquefied petroleum gas is treated into the gas phase liquefied petroleum gas through volume expansion gasification treatment.

2. The method according to claim 1, It is characterized in that Before the sampling step, the method further includes: sealing and slidingly arranging a piston in an inner cavity, thereby isolating the sample cavity in the inner cavity; The sampling step comprises: The sample cavity is connected with the sample source, so that the liquid phase liquefied petroleum gas slowly flows from the sample source into the sample cavity, and the piston is controlled to slide in the inner cavity according to the pressure of the sample source, so that the volume of the sample cavity is adaptively increased and the pressure of the sample cavity is consistent with the pressure of the sample source; The sample chamber is disconnected from the sample source until the liquid phase liquefied petroleum gas in the sample chamber reaches the preset sampling volume.

3. The method according to claim 2, It is characterized in that Before the sampling step, the method further comprises: The inner cavity is divided into a sample cavity and a pressure stabilizing cavity by the piston; wherein the pressure stabilizing cavity and the sample cavity are located on both sides of the piston; Connecting the pressure-stabilizing chamber with a pressure-stabilizing gas source so that the pressure-stabilizing gas flows from the pressure-stabilizing gas source into the pressure-stabilizing chamber, thereby pushing the piston to move toward the sample chamber; Until the volume of the sample chamber is minimized, the pressure-stabilizing chamber and the pressure-stabilizing gas source are disconnected.

4. The method according to claim 3, It is characterized in that The sampling step comprises: Controlling the pressure of the pressure-stabilizing chamber to be equal to the pressure of the sample source; The sample chamber is connected with the sample source so that the liquefied petroleum gas in the liquid phase slowly flows from the sample source into the sample chamber, and the pressure-stabilizing gas in the pressure-stabilizing chamber is slowly discharged, so that the piston is pushed to slide slowly toward one side of the pressure-stabilizing chamber under the pressure difference between the pressure-stabilizing chamber and the sample chamber, and the pressure of the sample chamber is consistent with the pressure of the sample source; The sample chamber is disconnected from the sample source until the liquid phase liquefied petroleum gas in the sample chamber reaches the preset sampling volume.

5. The method according to claim 3, It is characterized in that Before the sampling step, the method further comprises: connecting the sample chamber with a vacuum pump; Starting the vacuum pumping device to evacuate the sample chamber; Until the sample chamber reaches a preset vacuum degree, the sample chamber and the vacuum pumping device are disconnected.

6. The method according to claim 3, It is characterized in that Before the sampling step, the preset sampling volume is determined according to a phase diagram, a maximum volume of the sample chamber, and a pressure of the sample source; The gasification step includes: discharging all the pressure-stabilizing gas in the pressure-stabilizing chamber, so that the piston moves toward the pressure-stabilizing chamber to maximize the volume of the sample chamber, and the liquid phase liquefied petroleum gas is processed into gas phase liquefied petroleum gas in the sample chamber.

7. The method according to claim 1, It is characterized in that The gasification step further comprises: Gas homogenization treatment: the gas phase liquefied petroleum gas in the sample cavity is evenly distributed in various areas in the sample cavity.

8. The method according to claim 7, It is characterized in that The gas homogenization step includes: oscillating the sample cavity for a preset time so that the gas phase liquefied petroleum gas inside is evenly distributed in various areas of the sample cavity.

9. A device for sampling and processing liquefied petroleum gas, It is characterized in that include: The device body has an inner cavity; A piston is sealingly and slidably disposed in the inner cavity and separates a sample cavity from the inner cavity; A sampling valve is connected to the sample chamber.

10. The device according to claim 9, It is characterized in that The piston also separates a pressure-stabilizing chamber from the inner chamber. The pressure-stabilizing chamber and the sample chamber are located on both sides of the piston. The device also includes a gas valve, which is connected to the pressure-stabilizing chamber.

11. The device according to claim 10, It is characterized in that The device also includes a pressure-stabilizing exhaust valve, which is communicated with the pressure-stabilizing chamber.

12. The device according to claim 9, It is characterized in that The device also includes a sample end exhaust valve, which is communicated with the sample chamber.

13. The device according to claim 9, It is characterized in that The device body is a transparent visible structure, and a capacity identification structure is arranged on the device body.

Images