Low-boiling-point polymer solution sampling system and method

Abstract

The invention provides a low-boiling-point polymer solution sampling system. The low-boiling-point polymer solution sampling system comprises a sampling unit and a replacement unit connected with the sampling unit, the sampling unit comprises a sampling pipeline and a sampler; the replacement unit comprises a solvent replacement pipeline and a gas replacement pipeline; an outlet of the gas replacement pipeline is connected with the sampler and is used for enabling gas in the gas replacement pipeline to carry out gas replacement and pressurization on the sampler; an outlet of the solvent replacement pipeline is connected with the sampling pipeline and is used for carrying out solvent replacement and pressurization on the sampling pipeline by a solvent capable of dissolving the polymer in the solvent replacement pipeline; the sampler is used for receiving the low-boiling-point polymer solution or solvent from the sampling pipeline; the invention also provides a method for sampling by adopting the sampling system. By adopting the method provided by the invention for sampling, the problems that the sampling pipeline is blocked by solvent gasification and polymer precipitation and solidification and the safety problem is easily caused by solvent gasification can be effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of polymer solution sampling technology, and specifically relates to a low-boiling-point polymer solution sampling system and method. Background Technology

[0002] High-value-added polymers are often produced using solution polymerization or homogeneous bulk polymerization processes, such as POE, polybutene-1, ethylene propylene rubber, polytetramethyl-1-pentene, and SEBS. Sampling and analysis are important means of understanding the physical properties of polymer products at each stage of production, such as the melt index, polymerization composition, and catalytic activity of polymers in each reactor. Analyzing these physical properties can provide a reference for process adjustment and equipment optimization.

[0003] Solution polymerization and homogeneous bulk polymerization processes are generally characterized by high pressure, high temperature, and the frequent use of low-boiling-point solvents. For example, in homogeneous bulk polymerization, the poly-1-butene unit uses the monomer 1-butene as a solvent to dissolve the polymerized poly-1-butene resin. The pressure in the operating units (reaction units, monomer removal units) involving the 1-butene / poly-1-butene solution can reach 1-5 MPa, and the temperature can reach 50-300°C. Similarly, POE and ethylene propylene rubber often use low-boiling-point hexane as a solvent. In some operating units involving polymer solutions, the pressure can reach 3 MPa, and the temperature can reach 130°C. Under these high-temperature and high-pressure production conditions, sampling of low-boiling-point polymer solutions can easily lead to polymer precipitation, solidification, and blockage of the pipelines, ultimately resulting in sampling failure and posing safety risks.

[0004] Therefore, developing a novel sampling facility and method for low-boiling-point polymer solutions has industrial value. Summary of the Invention

[0005] To address the problems in existing technologies where sampling low-boiling-point polymer solutions is prone to polymer precipitation and solidification that can clog sampling pipelines, as well as the safety risks posed by solvent vaporization, this invention provides a low-boiling-point polymer solution sampling system and method. This system aims to prevent or minimize polymer precipitation within the pipeline during the sampling process, thereby reducing pipeline blockage and safety risks, and achieving reliable real-time online sampling.

[0006] The objective of this invention is mainly achieved through the following technical solutions.

[0007] In a first aspect, the present invention provides a low-boiling-point polymer solution sampling system, the system comprising a sampling line, a sampler, a solvent replacement line, and a gas replacement line.

[0008] The outlet end of the sampling pipeline is connected to the sampler, and the inlet end is configured to be connected to a container storing a low-boiling-point polymer solution, for conveying the low-boiling-point polymer solution to the sampler.

[0009] The outlet end of the gas replacement pipeline is connected to the sampler, and the inlet end is configured to be connected to a gas source for gas replacement and pressurization of the sampler.

[0010] The outlet end of the solvent replacement pipeline is connected to the sampling pipeline, and the inlet end is configured to be connected to the solvent source for solvent replacement and pressurization of the sampling pipeline.

[0011] Valves are provided on the sampling line, the solvent replacement line, and the gas replacement line.

[0012] Preferably, the valves on the sampling pipeline include a first valve at the inlet and a second valve at the outlet, and the outlet of the solvent displacement pipeline is connected to the sampling pipeline between the first valve and the second valve.

[0013] And / or, the valves on the solvent replacement line include a third valve located at the outlet; the valves on the gas replacement line include a fourth valve.

[0014] Preferably, the system further includes a discharge pipeline, a fifth valve is provided on the discharge pipeline, and one end of the discharge pipeline is connected to the sampler for discharging the gas phase in the sampler.

[0015] Preferably, one end of the discharge line is connected to the gas replacement line and the connection is located between the fourth valve and the sampler.

[0016] Preferably, the outlet end of the gas displacement pipeline is connected to the top of the sampler, and the outlet end of the sampling pipeline is connected to the upper middle part of the sampler.

[0017] Preferably, the system is designed with a pressure and temperature higher than that of the container storing the low-boiling-point polymer solution.

[0018] Preferably, the solvent replacement line is provided with a heat tracing line for heating the replacement solvent in the solvent replacement line.

[0019] Secondly, the present invention provides a method for sampling a low-boiling-point polymer solution, the method comprising the following steps:

[0020] Step (1): The replacement gas is sent into the sampler through the gas replacement pipeline to replace and pressurize the sampler.

[0021] Step (2): The replacement solvent is sent into the sampling line through the solvent replacement line to replace and pressurize the sampling line.

[0022] Step (3) involves introducing a low-boiling-point polymer solution into the sampler via the sampling line, during which the sampling line is filled with liquid.

[0023] Step (4): The sampling line is substituted again with a replacement solvent through the solvent replacement line.

[0024] Step (5): Remove the polymer from the sampler.

[0025] Preferably, step (1) includes: closing the second valve and opening the fourth valve, sending replacement gas into the sampler through the gas replacement pipeline, performing gas replacement and pressurization on the sampler, and then closing the fourth valve.

[0026] Preferably, the pressure of the sampler after pressurization is higher than the saturated vapor pressure of the replacement solvent.

[0027] Preferably, step (2) includes: closing the first valve and the second valve, opening the third valve, sending the replacement solvent into the sampling line through the solvent replacement pipeline to replace and pressurize the sampling line, and then closing the third valve.

[0028] Preferably, the pressure of the sampling line after pressurization is higher than the saturated vapor pressure of the replacement solvent.

[0029] Preferably, step (3) includes: opening the first valve and the second valve to allow the low-boiling-point polymer solution to enter the sampler via the sampling line, and closing the second valve.

[0030] Preferably, step (4) includes: opening the first valve and the third valve, using the replacement solvent to replace the sampling line with solvent in the direction of the first valve through the solvent replacement pipeline, and closing the first valve after replacement; opening the second valve, using the replacement solvent to replace the sampling line with solvent in the direction of the sampler through the solvent replacement pipeline, and closing the second valve and the third valve after replacement.

[0031] Preferably, the method further includes step (3-1) between step (3) and step (4), wherein after step (3) is completed, the fifth valve is opened to discharge the gas phase in the sampler, and then the fifth valve is closed.

[0032] Preferably, the method further includes step (4-1) between step (4) and step (5): opening the fifth valve to discharge the gas phase in the sampler; then closing the fifth valve, opening the fourth valve, allowing the gas in the gas replacement pipeline to enter the sampler for pressurization, closing the fourth valve, opening the fifth valve, discharging the gas phase in the sampler, and completing the gas replacement.

[0033] Preferably, the pressure of the sampling pipeline after pressurization is 0-5 MPa higher than the saturated vapor pressure of the replacement solvent, and more preferably 0.2-1 MPa.

[0034] Preferably, the pressure of the sampler after pressurization is 0-5 MPa higher than the saturated vapor pressure of the replacement solvent, and more preferably 0.2-1 MPa.

[0035] Preferably, the temperature of the replacement solvent in the solvent replacement pipeline is higher than the crystallization temperature of the polymer in the polymer solution and lower than the bubble point temperature of the replacement solvent; preferably, the temperature of the replacement solvent is more than 10°C lower than the bubble point temperature.

[0036] Preferably, the liquid level of the polymer solution in the sampler is lower than the connection point between the sampling line and the sampler.

[0037] The low-boiling-point polymer solution sampling system and method disclosed in this invention have the following advantages:

[0038] (1) The polymerization reaction can be sampled online in real time without stopping the polymerization reaction, and the polymerization reaction process can be monitored in real time.

[0039] (2) During the sampling process, reduce or avoid solvent vaporization in the sampling pipeline, and ensure that no polymer is released or only a very small amount of polymer is released in the sampling pipeline (release amount < 0.01 g / m³). 3 (Low-boiling-point polymer solution), the vaporized solvent in the system is discharged into the tail gas treatment system, which is safe and environmentally friendly. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a low-boiling-point polymer solution sampling system and method according to the present invention;

[0041] Figure 2 This is a schematic diagram of the low-boiling-point polymer solution sampling system of Comparative Example 1 of the present invention. Detailed Implementation

[0042] The preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings, which form part of the invention and, together with the embodiments thereof, serve to illustrate the principles of the invention.

[0043] In a first aspect, the present invention provides a sampling system for low-boiling-point polymer solutions. For example... Figure 1 As shown, the system of the present invention includes a sampling line 1, a sampler 2, a solvent replacement line 3, and a gas replacement line 4.

[0044] The outlet end of the sampling line 1 is connected to the sampler 2, and the inlet end is configured to be connected to a container storing a low-boiling-point polymer solution, for conveying the low-boiling-point polymer solution to the sampler 2.

[0045] The outlet end of the gas replacement pipeline 4 is connected to the sampler 2, and the inlet end is configured to be connected to a gas source for gas replacement and pressurization of the sampler 2.

[0046] The outlet end of the solvent replacement line 3 is connected to the sampling line 1, and the inlet end is configured to be connected to the solvent source for solvent replacement and pressurization of the sampling line 1.

[0047] Valves are installed on the sampling line 1, the solvent replacement line 3, and the gas replacement line 4.

[0048] In this invention, after solvent replacement of the sampling line 1, a certain pressure needs to be maintained in the sampling line 1 to reduce or avoid the vaporization of the solvent. In a preferred embodiment, the valves on the sampling line 1 include a first valve 5 disposed at the inlet end and a second valve 6 disposed at the outlet end, for maintaining the pressure in the sampling line 1; the first valve 5 and the second valve 6 can also be used to adjust the flow rate of the low-boiling-point polymer solution in the sampling line 1.

[0049] In this invention, the outlet end of the solvent replacement line 3 is connected to the sampling line 1 between the first valve 5 and the second valve 6.

[0050] In a preferred embodiment of the present invention, the valve on the solvent replacement line 3 includes a third valve 7 disposed at the outlet end, and the valve on the gas replacement line 4 includes a fourth valve 8, which are used to regulate the flow rates of the replacement solvent and gas in the solvent replacement line 3 and the gas replacement line 4, respectively, and to regulate the pressure in the sampling line 1 and the sampler 2.

[0051] In a preferred embodiment of the present invention, the system further includes a discharge line 9, on which a fifth valve 10 is provided, and one end of the discharge line 9 is connected to the sampler 2 for discharging the gas phase in the sampler 2. In this embodiment, one end of the gas replacement line 4 and one end of the discharge line 9 are independently connected to the top of the sampler 2, or one end of the discharge line 9 is connected to the gas replacement line 4 with the connection point located between the fourth valve 8 and the sampler 2.

[0052] The present invention does not have any special requirements for the above two connection methods of the discharge pipeline 9, and the above two connection methods do not affect the technical effect of the present invention.

[0053] In a preferred embodiment of the present invention, the outlet end of the gas replacement pipeline 4 is connected to the top of the sampler 2, and the outlet end of the solvent sampling pipeline 1 is connected to the upper middle part of the sampler 2. With this preferred embodiment, the replacement gas in the gas replacement pipeline 4 will not enter the low-boiling-point polymer solution in the sampler 2 during the process of entering the sampler 2, thus avoiding foaming and boiling. Furthermore, the gas phase in the sampler 2 can be discharged from the top of the sampler 2 through the discharge pipeline 9 due to the pressure and then enter the tail gas treatment system.

[0054] In a preferred embodiment of the present invention, the design pressure and design temperature of the system are higher than the design pressure and design temperature of the container storing the low-boiling-point polymer solution.

[0055] This invention does not impose any particular limitation on the container used to store the low-boiling-point polymer solution; any container conventionally used in the art can be used, such as a polymer reactor, flash tank, or storage tank. The design pressure of the container storing the low-boiling-point polymer solution is higher than the saturated vapor pressure of the displacing solvent at the design temperature at which the container displaces the low-boiling-point polymer solution. Furthermore, the design pressure and temperature of the system are higher than those of the container storing the low-boiling-point polymer solution. This ensures that the working pressure and temperature of the sampling system will not exceed its design temperature and pressure during the sampling operation, guaranteeing that the polymer in the polymer solution does not precipitate or precipitates in very small amounts during the sampling process, and ensuring the safe operation of the sampling process.

[0056] In a preferred embodiment of the present invention, the solvent replacement line 3 is provided with a heating line 11 for heating the replacement solvent in the solvent replacement line 3; after the replacement solvent is heated, it is maintained at a relatively high temperature before entering the sampling line 1, which can prevent the line from losing temperature or prevent the low-boiling-point polymer solution from precipitating polymer due to excessive temperature drop.

[0057] Secondly, the present invention provides a method for sampling a low-boiling-point polymer solution, the method comprising the following steps:

[0058] Step (1): The replacement gas is sent into the sampler 2 through the gas replacement pipeline 4 to perform gas replacement and pressurization on the sampler 2.

[0059] Step (2): The replacement solvent is sent into the sampling line 1 through the solvent replacement line 3 to replace and pressurize the sampling line 1.

[0060] Step (3) involves introducing the low-boiling-point polymer solution into the sampler 2 via the sampling line 1. During the flow of the low-boiling-point polymer solution through the sampling line 1, the sampling line 1 is in a full liquid state.

[0061] Step (4): The sampling line 1 is substituted again with a replacement solvent through the solvent replacement line 3.

[0062] Step (5): Remove the polymer from the sampler 2.

[0063] The inventors of this invention have discovered through research that operating in the order of steps (1) to (5) can effectively prevent the vaporization of the solvent in sampling line 1 and the precipitation and solidification of the polymer in the low-boiling-point polymer solution. In particular, after using a replacement solvent to replace and pressurize sampling line 1 in step (2), sampling line 1 is filled with replacement solvent. At this time, the low-boiling-point polymer solution in step (3) is in a high-pressure environment from the moment it enters sampling line 1, avoiding the evaporation of the solvent in the low-boiling-point polymer solution and thus preventing the precipitation of the polymer. At the same time, it can effectively avoid the safety problems that may occur due to the vaporization of the solvent during the sampling process. Moreover, after the sampling is completed, there is no residue of the low-boiling-point polymer solution in sampling line 1 and sampler 2, and there will be no blockage of sampling line 1. The method of this invention is particularly suitable for low-boiling-point polymer solutions, and the replacement solvent in the solvent replacement line 1 is the same as the solvent in the low-boiling-point polymer solution. For safety reasons, the replacement gas in the gas replacement pipeline 4 of the present invention is preferably an inert gas, preferably nitrogen, argon, helium, or neon, and more preferably nitrogen.

[0064] Based on the above research, in this invention, the replacement solvent in the solvent replacement pipeline 1 is the same as the solvent in the low-boiling-point polymer solution.

[0065] In a preferred embodiment of the present invention, step (1) includes closing the second valve 6 and opening the fourth valve 8, sending the replacement gas into the sampler 2 through the gas replacement pipeline 4, performing gas replacement and pressurization on the sampler 2, and then closing the fourth valve 8.

[0066] In a more preferred embodiment of the present invention, step (1) includes: closing the second valve 6 and the fifth valve 10, opening the fourth valve 8, sending replacement gas into the sampler 2 through the gas replacement pipeline 4 to pressurize the sampler 2, then closing the fourth valve 8, opening the fifth valve 10 to discharge the gas phase in the sampler 2, closing the fifth valve 10, opening the fourth valve 8, pressurizing the sampler 2 to complete the gas replacement and pressurization, and closing the fourth valve 8. By employing this preferred embodiment to complete the gas replacement and pressurization of the sampler 2, the sampler 2 maintains a high-pressure state, thereby ensuring that during step (3), the sampling pipeline 1 maintains a high-pressure state higher than the saturated vapor pressure of the replacement solvent, avoiding polymer precipitation due to solvent evaporation. In addition, by closing the second valve 6 and the fifth valve 10 and opening the fourth valve 8, the sampler 2 is connected to the outside through only one channel, which can efficiently complete the pressurization operation of the sampler 2. Then, the fourth valve 8 is closed and the fifth valve 10 is opened. After stopping the air intake into the sampler 2, the gas phase in the sampler 2 is discharged from the discharge pipeline 9 through the fifth valve 10 due to the pressure inside the sampler 2.

[0067] The present invention does not impose any particular limitation on the number of times gas replacement and pressurization are performed in step (1), as long as the gaseous solvent in the sampler 2 can be completely replaced and filled with replacement gas. In a preferred embodiment of the present invention, the gas replacement and pressurization in step (1) are repeated 1-10 times, preferably 3-6 times.

[0068] In a preferred embodiment of the present invention, the pressure of the sampler 2 after pressurization is higher than the saturated vapor pressure of the displacement solvent; by adopting this preferred embodiment, the vaporization of the displacement solvent in the sampling pipeline 1 can be avoided during the sampling process.

[0069] In a preferred embodiment of the present invention, step (2) includes closing the first valve 5 and the second valve 6, opening the third valve 7, sending the replacement solvent into the sampling line 1 through the solvent replacement line 3 to perform solvent replacement and pressurization on the sampling line 1, and then closing the third valve 7.

[0070] In a preferred embodiment of the present invention, the pressure of the sampling line 1 after pressurization is higher than the saturated vapor pressure of the displacement solvent.

[0071] In a preferred embodiment of the present invention, step (3) includes opening the first valve 5 and the second valve 6 to allow the low-boiling-point polymer solution to enter the sampler 2 via the sampling line 1, and then closing the second valve 6. During the flow of the low-boiling-point polymer solution through the sampling line 1, the sampling line 1 remains pressurized to prevent solvent evaporation and polymer precipitation that could clog the line. In the present invention, it is understood that in step (3), after opening the first valve 5 and the second valve 6, the pressure in the sampling line 1 will fluctuate the instant the low-boiling-point polymer solution in the container begins to enter the sampling line 1. Then, under the pressure of the container storing the low-boiling-point polymer solution, the pressure in the sampling line 1 will gradually increase amidst these fluctuations. If the pressure in the sampling line 1 after replacement and pressurization is too low, the pressure in the sampling line 1 may be lower than the saturated vapor pressure of the replacement solvent at the instant the low-boiling-point polymer solution enters the sampling line 1, due to pressure fluctuations, causing some solvent to vaporize and precipitate as polymer.

[0072] In a preferred embodiment of the present invention, step (4) includes: opening the first valve 5 and the third valve 7; using the replacement solvent through the solvent replacement pipeline 3 to replace the sampling pipeline 1 towards the first valve 5; and closing the first valve 5 after replacement. Then, opening the second valve 6; using the replacement solvent through the solvent replacement pipeline 3 to replace the sampling pipeline 1 towards the sampler 2; and closing the second valve 6 and the third valve 7 after replacement. This preferred embodiment ensures that no low-boiling-point polymer solution residue remains in the sampling pipeline 1, avoiding polymer precipitation, solidification, and pipeline blockage, as well as safety issues related to solvent vaporization.

[0073] In a preferred embodiment of the present invention, the method further includes step (3-1) performed between step (3) and step (4): after step (3) is completed, the fifth valve 10 is opened to discharge the gas phase in the sampler 2, and then the fifth valve 10 is closed. This preferred embodiment allows for timely discharge of the solvent in the sampler 2, reducing the pressure in the sampler 2. This facilitates sufficient displacement of the section of pipeline between the outlet of the solvent displacement pipeline 3 and the connection point of the sampling pipeline 1 to the sampler 2 during solvent displacement in step (4), preventing the low-boiling-point polymer solution from remaining in the sampling pipeline 1. Furthermore, the gas phase discharged from the sampler 2 enters the exhaust gas treatment system, preventing atmospheric pollution or safety issues.

[0074] In a preferred embodiment of the present invention, the method further includes step (4-1) performed between step (4) and step (5): opening the fifth valve 10 to discharge the gas phase in the sampler 2; then closing the fifth valve 10, opening the fourth valve 8, allowing the replacement gas in the gas replacement pipeline 4 to enter the sampler 2 for pressurization, closing the fourth valve 8, opening the fifth valve 10, and discharging the gas phase in the sampler 2 through the discharge pipeline 9, thus completing the gas replacement. Performing step (4-1) before step (5) allows the solvent in the sampler 2 to vaporize and discharge from the sampler 2 under conditions lower than the saturated vapor pressure of the replacement solvent, reducing the residual amount of solvent in the sampler 2.

[0075] The present invention does not impose any particular restrictions on the method of removing the polymer from the sampler 2, because step (4-1) of the present invention leaves only the polymer in the sampler 2, at which point the polymer is in a solid state. Therefore, a preferred embodiment is to design the bottom end of the sampler 2 as a flange seal, so that the solid polymer can be removed from the sampler 2 simply by opening the flange.

[0076] The present invention does not impose any particular limitation on the number of times the gas replacement is performed in step (4-1), as long as the gaseous solvent in the sampler 2 can be completely replaced. In a preferred embodiment of the present invention, the gas replacement in step (4-1) is repeated 1-10 times, preferably 3-6 times.

[0077] In a preferred embodiment of the present invention, the pressure of the sampling pipeline 1 after pressurization is 0-5 MPa higher than the saturated vapor pressure of the replacement solvent, preferably 0.2-1 MPa.

[0078] In a preferred embodiment of the present invention, the pressure of the sampler 2 after pressurization is 0-5 MPa higher than the saturated vapor pressure of the replacement solvent, preferably 0.2-1 MPa.

[0079] In a preferred embodiment of the present invention, the temperature of the solvent in the solvent replacement line 3 is higher than the crystallization temperature of the polymer in the polymer solution, but lower than the bubble point temperature of the replacement solvent; preferably, the temperature of the replacement solvent is more than 10°C lower than the bubble point temperature. The bubble point temperature refers to the bubble point temperature under replacement solvent pressure.

[0080] In a preferred embodiment of the present invention, the liquid level of the polymer solution in the sampler 2 is lower than the connection position between the sampling line 1 and the sampler 2.

[0081] In a preferred embodiment of the present invention, the connection between the gas replacement pipeline 3 and the discharge pipeline 9 is farther away from the sampler 2 than the third valve 7;

[0082] And / or, the gas replacement line 3 is further provided with a fifth valve 10, which is further away from the sampler 2 than the connection between the gas replacement line 3 and the discharge line 9.

[0083] The shape and structure of the sampler 2 are not particularly limited in this invention, as long as it is convenient to hold the low-boiling-point polymer solution and easy to remove the polymer. It can be cylindrical, cubic, spherical, etc., and is preferably cylindrical. The size of the cylindrical sampler 2 is not particularly limited, and the specific size can be determined according to the required sample volume.

[0084] In this invention, there are no particular restrictions on the dimensions of the sampling line 1, solvent replacement line 2, gas replacement line 3, and discharge line 9. Preferably, the volume of the sampling line 1 is less than 5% of the volume of the sampler 2.

[0085] In this invention, there is no particular choice for the selection of the first valve 5, the second valve 6, the third valve 7, the fourth valve 8, and the fifth valve 10. They can be commonly used in the art, such as plunger valves, regulating valves, gate valves, and ball valves. Preferably, the first valve 5, the second valve 6, the third valve 7, the fourth valve 8, and the fifth valve 10 are regulating valves.

[0086] The present invention does not limit the opening degree of the first valve 5, the second valve 6, the third valve 7, the fourth valve 8 and the fifth valve 10, and can adjust them according to the actual situation, as long as the pressure in the sampling pipeline 1 and the sampler 2 is higher than the saturated vapor pressure of the replacement solvent during the replacement and pressing process.

[0087] The following detailed description of preferred embodiments of the present invention illustrates the principles of the invention and is not intended to limit the scope of the invention.

[0088] The following examples show that samples were taken from the first reactor of a thousand-ton-scale industrial demonstration plant for the homogeneous bulk polybutene-1 process using monomer 1-butene as a solvent. The first reactor was operated at a temperature of 80°C and a pressure of 2.5 MPa, and samples were taken at two different time intervals:

[0089] In the first time period, the content of polybutene-1 in the poly-1-butene solution A was 20%. Under the above-mentioned working temperature and pressure, the saturated vapor pressure of 1-butene was 1.1 MPa, and the bubble point temperature was 108℃. The crystallization temperature of polybutene-1 was 70℃.

[0090] In the second time period, the polybutene-1 content in the poly-1-butene solution B was 35%. Under the aforementioned working temperature and pressure, the saturated vapor pressure of 1-butene was 1.1 MPa, and the bubble point temperature was 108°C. The crystallization temperature of polybutene-1 was 70°C.

[0091] The replacement solvent is 1-butene.

[0092] All pipelines in the low-boiling-point polymer solution sampling system are 1 / 2 inch in diameter, designed for a pressure of 10 MPa and a temperature of 250°C; all valves are designed for a pressure of 10 MPa and a temperature of 250°C.

[0093] The gas detector is an INSCO M40PRO.

[0094] Example 1

[0095] This embodiment provides a method for sampling low-boiling-point polymer solutions, referencing... Figure 1 The specific steps are as follows.

[0096] Step (1): Close the second valve 6 and the fifth valve 10, open the fourth valve 8, and use nitrogen gas to pressurize the sampler 2 (which is cylindrical, with an inner diameter of 250 mm, a height of 500 mm, flange connections at the upper and lower ends, a design pressure of 10 MPa, and a design temperature of 250 °C) to 1.7 MPa through the gas replacement pipeline 4. Then close the fourth valve 8, open the fifth valve 10, and discharge the gas phase in the sampler 2 through the discharge pipeline 9. Close the fifth valve 10 to complete one gas replacement and pressurization. Repeat the gas replacement and pressurization three times. After completion, pressurize to 1.7 MPa again and close the fifth valve 10.

[0097] Step (2): Close the first valve 5 and the second valve 6, and open the third valve 7, so that the 1-butene (flow rate is 0.5 m³) can be released. 3 The sampling line 1 is filled with 1-butene at a pressure of 8 MPa per hour through the solvent replacement line 3 (heated line 11 at a temperature of 85 ± 2 °C). After the pressure reaches 1.7 MPa, the third valve 7 is closed.

[0098] Step (3): Open the first valve 5 and the second valve 6 in sequence, so that the low-boiling point poly-1-butene solution A in the first-stage flash tank enters the sampler 2 through the sampling line 1, and then close the second valve 6. During the process of the low-boiling point poly-1-butene solution A flowing through the sampling line 1, the sampling line 1 is full of liquid and the temperature is 85°C; the liquid level in the sampler 2 is lower than the connection between the sampling line 1 and the sampler 2.

[0099] Step (3-1): Open the fifth valve 10, discharge the gas phase in the sampler 2 through the discharge pipeline 9, and then close the fifth valve 10.

[0100] Step (4): Close the second valve 6, open the first valve 5 and the third valve 7, and the 1-butene displaces the sample line 1 through the solvent replacement pipeline 3 towards the first valve 5. After the 1-butene fills the sample line 1, close the first valve 5. Then open the second valve 6, and the 1-butene displaces the sample line 1 through the solvent replacement pipeline 3 towards the sampler 2. After the 1-butene fills the sample line 1, close the second valve 6 and the third valve 7.

[0101] Step (4-1): Open the fifth valve 10 to discharge the gas phase in the sampler 2, and continue to discharge for 60 minutes;

[0102] Then, the fifth valve 10 is closed, the fourth valve 8 is opened, and the nitrogen gas enters the sampler 2 through the gas replacement pipeline 4 and is pressurized to 1 MPa. The fourth valve 8 is closed, the fifth valve 10 is opened, and the gas phase in the sampler 2 is discharged through the discharge pipeline 9. The fifth valve 10 is then closed, completing one gas replacement cycle. The pressurization and discharge are then repeated three times to complete the gas replacement cycle.

[0103] Step (5): Open the flange at the bottom of the sampler 2 and remove poly-1-butene from it.

[0104] Testing revealed no solid precipitation in sampling line 1, and no 1-butene was detected in the atmosphere surrounding the sampling system using a gas detector. No 1-butene residue was found in sampler 2.

[0105] Example 2

[0106] This embodiment provides a method for sampling low-boiling-point polymer solutions, referencing... Figure 1 The specific steps are as follows.

[0107] Step (1): Close the second valve 6 and the fifth valve 10, open the fourth valve 8, and use nitrogen gas to pressurize the sampler 2 (which is cylindrical, with an inner diameter of 250 mm, a height of 500 mm, flange connections at the upper and lower ends, a design pressure of 10 MPa, and a design temperature of 250 °C) to 1.3 MPa through the gas replacement pipeline 4. Then close the fourth valve 8, open the fifth valve 10, and discharge the gas phase in the sampler 2 through the discharge pipeline 9. Close the fifth valve 10 to complete one gas replacement and pressurization. Repeat the gas replacement and pressurization three times. After completion, pressurize to 1.3 MPa again and close the fifth valve 10.

[0108] Step (2): Close the first valve 5 and the second valve 6, and open the third valve 7, so that the 1-butene (flow rate is 0.5 m³) can be released. 3The sampling line 1 is filled with 1-butene at a pressure of 8 MPa and the solvent replacement line 3 (heated line 11 at a temperature of 85 ± 2 °C) is used to replace and pressurize the sampling line 1. After the pressure reaches 1.3 MPa, the third valve 7 is closed.

[0109] Step (3): Sequentially use the first valve 5 and the second valve 6 to allow the low-boiling-point poly-1-butene solution A in the first-stage flash tank to enter the sampler 2 through the sampling line 1. Then close the second valve 6. During the process of the low-boiling-point poly-1-butene solution A flowing through the sampling line 1, the sampling line 1 is in a full liquid state with a temperature of 85°C. The liquid level in the sampler 2 is lower than the connection between the sampling line 1 and the sampler 2.

[0110] Step (3-1): Open the fifth valve 10, discharge the gas phase in the sampler 2 through the discharge pipeline 9, and then close the fifth valve 10.

[0111] Step (4): Close the second valve 6, open the first valve 5 and the third valve 7, and the 1-butene displaces the sample line 1 through the solvent replacement pipeline 3 towards the first valve 5. After the 1-butene fills the sample line 1, close the first valve 5. Then open the second valve 6, and the 1-butene displaces the sample line 1 through the solvent replacement pipeline 3 towards the sampler 2. After the 1-butene fills the sample line 1, close the second valve 6 and the third valve 7.

[0112] Step (4-1): Open the fifth valve 10 to discharge the gas phase in the sampler 2, and continue to discharge for 60 minutes;

[0113] Then, the fifth valve 10 is closed, the fourth valve 8 is opened, and the nitrogen gas enters the sampler 2 through the gas replacement pipeline 4 and is pressurized to 1 MPa. The fourth valve 8 is closed, the fifth valve 10 is opened, and the gas phase in the sampler 2 is discharged through the discharge pipeline 9. The fifth valve 10 is then closed, completing one gas replacement cycle. The pressurization and discharge are then repeated three times to complete the gas replacement cycle.

[0114] Step (5): Open the flange at the bottom of the sampler 2 and remove poly-1-butene from it.

[0115] Testing revealed no solid precipitation in sampling line 1, and no 1-butene was detected in the atmosphere surrounding the sampling system using a gas detector. No 1-butene residue was found in sampler 2.

[0116] Example 3

[0117] This embodiment provides a method for sampling low-boiling-point polymer solutions, referencing... Figure 1 The specific steps are as follows.

[0118] Step (1): Close the second valve 6 and the fifth valve 10, open the fourth valve 8, and pressurize the sampler 2 (cylindrical, with an inner diameter of 250 mm, a height of 500 mm, flange connections at the upper and lower ends, a design pressure of 10 MPa, and a design temperature of 250 °C) to 2.1 MPa using nitrogen gas through the gas replacement pipeline 4. Then close the fourth valve 8, open the fifth valve 10, and discharge the gas phase in the sampler 2 through the discharge pipeline 9. Close the fifth valve 10 to complete one gas replacement and pressurization. Repeat the gas replacement and pressurization three times. After completion, pressurize to 2.1 MPa again and close the fifth valve 10.

[0119] Step (2): Close the first valve 5 and the second valve 6, and open the third valve 7, so that the 1-butene (flow rate is 0.5 m³) can be released. 3 The sampling line 1 is filled with 1-butene at a pressure of 8 MPa and the solvent replacement line 3 (heated line 11 at a temperature of 85 ± 2 °C) is used to replace and pressurize the sampling line 1. After the pressure reaches 2.1 MPa, the third valve 7 is closed.

[0120] Step (3): Open the first valve 5 and the second valve 6 in sequence, so that the low-boiling-point poly-1-butene solution A in the first-stage flash tank enters the sampler 2 through the sampling line 1, and then close the second valve 6. During the process of the low-boiling-point poly-1-butene solution A flowing through the sampling line 1, the sampling line 1 is full of liquid and the temperature is 85°C; the liquid level in the sampler 2 is lower than the connection between the sampling line 1 and the sampler 2.

[0121] Step (3-1): Open the fifth valve 10, discharge the gas phase in the sampler 2 through the discharge pipeline 9, and then close the fifth valve 10.

[0122] Step (4): Close the second valve 6, open the first valve 5 and the third valve 7, and the 1-butene displaces the sample line 1 through the solvent replacement pipeline 3 towards the first valve 5. After the 1-butene fills the sample line 1, close the first valve 5. Then open the second valve 6, and the 1-butene displaces the sample line 1 through the solvent replacement pipeline 3 towards the sampler 2. After the 1-butene fills the sample line 1, close the second valve 6 and the third valve 7.

[0123] Step (4-1): Open the fifth valve 10 to discharge the gas phase in the sampler 2, and continue to discharge for 60 minutes;

[0124] Then, the fifth valve 10 is closed, the fourth valve 8 is opened, and the nitrogen gas enters the sampler 2 through the gas replacement pipeline 4 and is pressurized to 1 MPa. The fourth valve 8 is closed, the fifth valve 10 is opened, and the gas phase in the sampler 2 is discharged through the discharge pipeline 9. The fifth valve 10 is then closed, completing one gas replacement cycle. The pressurization and discharge are then repeated three times to complete the gas replacement cycle.

[0125] Step (5): Open the flange at the bottom of the sampler 2 and remove poly-1-butene from it.

[0126] Upon testing, no solid precipitate was found in sampling line 1. The atmosphere surrounding the sampling system was tested using a gas detector, and no 1-butene was detected. No 1-butene residue was found in sampler 2.

[0127] Example 4

[0128] This embodiment provides a method for sampling low-boiling-point polymer solutions, referencing... Figure 1 The specific steps are as follows.

[0129] Step (1): Close the second valve 6 and the fifth valve 10, open the fourth valve 8, and use nitrogen gas to pressurize the sampler 2 (which is cylindrical, with an inner diameter of 250 mm, a height of 500 mm, flange connections at the upper and lower ends, a design pressure of 10 MPa, and a design temperature of 250 °C) to 1.1 MPa through the gas replacement pipeline 4. Then close the fourth valve 8, open the fifth valve 10, and discharge the gas phase in the sampler 2 through the discharge pipeline 9. Close the fifth valve 10 to complete one gas replacement and pressurization. Repeat the gas replacement and pressurization three times. After completion, pressurize to 1.1 MPa again and close the fifth valve 10.

[0130] Step (2): Close the first valve 5 and the second valve 6, and open the third valve 7, so that the 1-butene (flow rate is 0.5 m³) can be released. 3 The sampling line 1 is filled with 1-butene at a pressure of 8 MPa and the solvent replacement line 3 (heated line 11 at a temperature of 85±2℃) is used to replace and pressurize the sampling line 1. After the pressure reaches 1.1 MPa, the third valve 7 is closed.

[0131] Step (3): Open the first valve 5 and the second valve 6 in sequence, so that the low-boiling-point poly-1-butene solution A in the first-stage flash tank enters the sampler 2 through the sampling line 1, and then close the second valve 6. During the process of the low-boiling-point poly-1-butene solution A flowing through the sampling line 1, the sampling line 1 is full of liquid and the temperature is 85°C; the liquid level in the sampler 2 is lower than the connection between the sampling line 1 and the sampler 2.

[0132] Step (3-1): Open the fifth valve 10, discharge the gas phase in the sampler 2 through the discharge pipeline 9, and then close the fifth valve 10.

[0133] Step (4): Close the second valve 6, open the first valve 5 and the third valve 7, and the 1-butene displaces the sample line 1 through the solvent replacement pipeline 3 towards the first valve 5. After the 1-butene fills the sample line 1, close the first valve 5. Then open the second valve 6, and the 1-butene displaces the sample line 1 through the solvent replacement pipeline 3 towards the sampler 2. After the 1-butene fills the sample line 1, close the second valve 6 and the third valve 7.

[0134] Step (4-1): Open the fifth valve 10 to discharge the gas phase in the sampler 2, and continue to discharge for 60 minutes;

[0135] Then, the fifth valve 10 is closed, the fourth valve 8 is opened, and the nitrogen gas enters the sampler 2 through the gas replacement pipeline 4 and is pressurized to 1 MPa. The fourth valve 8 is closed, the fifth valve 10 is opened, and the gas phase in the sampler 2 is discharged through the discharge pipeline 9. The fifth valve 10 is then closed, completing one gas replacement cycle. The pressurization and discharge are then repeated three times to complete the gas replacement cycle.

[0136] Step (5): Open the flange at the bottom of the sampler 2 and remove poly-1-butene from it.

[0137] Upon testing, 0.005 g / ml of poly-1-butene was found to have precipitated in sampling line 1. However, no 1-butene was detected in the atmosphere surrounding the sampling system using a gas detector, and no 1-butene residue was found in sampler 2.

[0138] Example 5

[0139] This embodiment provides a method for sampling low-boiling-point polymer solutions, referencing... Figure 1 The specific steps are as follows.

[0140] Step (1): Close the second valve 6 and the fifth valve 10, open the fourth valve 8, and use nitrogen gas to pressurize the sampler 2 (cylindrical, with an inner diameter of 250 mm, a height of 500 mm, flange connections at the upper and lower ends, a design pressure of 10 MPa, and a design temperature of 250 °C) to 6.1 MPa through the gas replacement pipeline 4. Then close the fourth valve 8, open the fifth valve 10, and discharge the gas phase in the sampler 2 through the discharge pipeline 9. Close the fifth valve 10 to complete one gas replacement and pressurization. Repeat the gas replacement and pressurization three times. After completion, pressurize to 6.1 MPa again and close the fifth valve 10.

[0141] Step (2): Close the first valve 5 and the second valve 6, and open the third valve 7, so that the 1-butene (flow rate is 0.5 m³) can be released. 3 The sampling line 1 is filled with 1-butene at a pressure of 8 MPa and the solvent replacement line 3 (heated line 11 at a temperature of 85 ± 2 °C) is used to replace and pressurize the sampling line 1. After the pressure reaches 6.1 MPa, the third valve 7 is closed.

[0142] Step (3): Open the first valve 5 and the second valve 6 in sequence, so that the low-boiling point poly-1-butene solution A in the first-stage flash tank enters the sampler 2 through the sampling line 1, and then close the second valve 6. During the process of the low-boiling point poly-1-butene solution A flowing through the sampling line 1, the sampling line 1 is full of liquid and the temperature is 85°C; the liquid level in the sampler 2 is lower than the connection between the sampling line 1 and the sampler 2.

[0143] Step (3-1): Open the fifth valve 10, discharge the gas phase in the sampler 2 through the discharge pipeline 9, and then close the fifth valve 10.

[0144] Step (4): Close the second valve 6, open the first valve 5 and the third valve 7, and the 1-butene displaces the sample line 1 through the solvent replacement pipeline 3 towards the first valve 5. After the 1-butene fills the sample line 1, close the first valve 5. Then open the second valve 6, and the 1-butene displaces the sample line 1 through the solvent replacement pipeline 3 towards the sampler 2. After the 1-butene fills the sample line 1, close the second valve 6 and the third valve 7.

[0145] Step (4-1): Open the fifth valve 10 to discharge the gas phase in the sampler 2, and continue to discharge for 60 minutes;

[0146] Then, the fifth valve 10 is closed, the fourth valve 8 is opened, and the nitrogen gas enters the sampler 2 through the gas replacement pipeline 4 and is pressurized to 1 MPa. The fourth valve 8 is closed, the fifth valve 10 is opened, and the gas phase in the sampler 2 is discharged through the discharge pipeline 9. The fifth valve 10 is then closed, completing one gas replacement cycle. The pressurization and discharge are then repeated three times to complete the gas replacement cycle.

[0147] Step (5): Open the flange at the bottom of the sampler 2 and remove poly-1-butene from it.

[0148] Upon testing, no solid precipitate was found in sampling line 1. No 1-butene was detected in the atmosphere surrounding the sampling system using a gas detection instrument, and no 1-butene residue was found in sampler 2.

[0149] Example 6

[0150] Sampling was performed according to the method in Example 1, except that step (4-1) was not performed.

[0151] Upon disassembly and testing of the pipeline, no solid precipitate was found in sampling pipeline 1. However, 1-butene was detected in the atmosphere surrounding the sampling system using a gas detector, indicating the presence of 1-butene residue within the sampler.

[0152] Example 7

[0153] Sampling was performed according to the method in Example 5, except that step (3-1) was not performed.

[0154] Upon disassembly and testing of the pipeline, 0.01 g / ml of poly-1-butene was found to have precipitated in sampling pipeline 1. However, no 1-butene was detected in the atmosphere surrounding the sampling system using a gas detector, and no 1-butene residue was found in the sampler 2.

[0155] Example 8

[0156] Sampling was performed according to the method of Example 1, except that in step (2), the 1-butene was not filled in the sampling pipeline 1 and the pressure was 0.8 MPa.

[0157] Testing revealed that poly-1-butene precipitated in sampling line 1 at a rate of 0.05 g / ml. Gas detectors were used to analyze the atmosphere surrounding the sampling system, and no 1-butene was detected. No 1-butene residue was found in sampler 2.

[0158] Example 9

[0159] Sampling was performed according to the method in Example 1, except that the poly-1-butene solution A to be sampled was replaced with poly-1-butene solution B.

[0160] Upon testing, poly-1-butene was found to have precipitated in sampling line 1, but no solid precipitate was found. The atmosphere surrounding the sampling system was tested with a gas detector and no 1-butene was detected. No 1-butene residue was found in sampler 2.

[0161] Comparative Example 1

[0162] The sampling method for this comparative example is referenced. Figure 2 As shown,

[0163] Step (1): Open the first valve 5 and the second valve 6 in sequence, so that the low-boiling-point polymer solution A in the first-stage flash tank enters the sampler 2 through the sampling line 1. Then close the second valve 6. During the process of the low-boiling-point polymer solution A flowing through the sampling line 1 (the temperature of the heating line 11 is 85±2℃), the sampling line 1 is full of liquid and the temperature is 85℃. The liquid level in the sampler 2 is lower than the connection between the sampling line 1 and the sampler 2.

[0164] Step (2): Open the fifth valve 10, discharge the gas phase in the sampler 2 through the discharge pipeline 9, and close the fifth valve 10.

[0165] Step (3): Open the flange at the bottom of the sampler 2 and remove poly-1-butene from it.

[0166] Upon testing, poly-1-butene was found to have precipitated in sampling line 1 at a rate of 0.08 g / ml. 1-Butene was also detected in the atmosphere surrounding the sampling system using a gas detector. 1-Butene residue was also found in sampler 2.

[0167] As can be seen from the above embodiments and comparative examples, by using the preferred technical solutions of the present invention in Embodiments 1-3 and Embodiment 9, sampling of low-boiling-point polymer solutions can not only achieve real-time online sampling, but also avoid the blockage of sampling pipelines during the sampling process, as well as avoid problems such as solvent vaporization causing explosions, deflagrations, and atmospheric pollution.

[0168] In Example 4, the pressure after replacing and stamping the sampling pipeline and sampler was not preferred, being 1.1 MPa. After sampling, 0.005 g / ml of solid precipitated in the sampling pipeline. In Example 1, the preferred stamping pressure was 1.7 MPa, and no solid precipitated.

[0169] In Example 5, the pressure after replacing and stamping the sampling pipeline and sampler is not preferred; it is 6.1 MPa. After sampling, no solid precipitates in the sampling pipeline. However, in step (3), backflow occurs between 1-butene in the sampling pipeline and nitrogen in the sampler, which impacts the reactor and can easily damage it. In Example 1, the preferred stamping pressure is 1.7 MPa, and no solid precipitates or backflow occurs.

[0170] In Example 6, step (4-1) was not performed, and no solid precipitated in sampling line 1. However, when sampling in the sampler, 1-butene was detected in the air around the sampler using a gas detection instrument. Analysis showed that because step (4-1) was not performed, 1-butene in sampler 2 was not fully discharged. Then, when sampling in step (5), there was solvent residue in sampler 2, and some of the solvent butene-1 leaked into the surrounding area. In Example 1, the preferred steps were used, and step (4-1) was performed. The solvent in sampler 2 was completely vaporized and discharged into the tail gas treatment system. There was no solvent residue in the sampler, and 1-butene was not detected in the surrounding area.

[0171] In Example 7, step (3-1) was not performed, and 0.01 g / ml of polybutene precipitated in sampling line 1. Analysis revealed that because step (3-1) was not performed, the limited volume of sampler 2 during solvent replacement in step (4) resulted in insufficient replacement of the section of sampling line 1 near sampler 2, leading to polymer solution residue and solid precipitation. In Example 1, the preferred steps were performed, including step (3-1), resulting in complete replacement of sampling line 1 with no residue and no solid precipitation.

[0172] In Example 8, the sampling line 1 was not completely filled with 1-butene, and the pressure in the sampling line 1 was only 0.8 MPa. After sampling, solid precipitated in the sampling line 1, with a precipitation amount of 0.05 g / ml. In Example 1, the preferred procedure was used, and the sampling line 1 was filled with 1-butene at a pressure of 1.7 MPa. After sampling, no solid precipitated.

[0173] Comparative Example 1 did not employ the technical solution of the present invention. Solvent replacement of sampling line 1 and gas replacement of sampler 2 were not performed. Solid precipitated in sampling line 1, with a precipitation amount of 0.08 g / ml. Solvent residue was found in sampler 2, and butene-1 was detected in the surrounding area. Example 1 employed the technical solution of the present invention. Solvent replacement of sampling line 1 and gas replacement of sampler 2 were performed before sampling. No solid precipitated after sampling, and no solvent residue was found in sampler 2.

[0174] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A sampling system for low-boiling-point polymer solutions, characterized in that, The system includes a sampling line (1), a sampler (2), a solvent replacement line (3), and a gas replacement line (4), wherein, The outlet end of the sampling line (1) is connected to the sampler (2), and the inlet end is configured to be connected to a container storing a low-boiling-point polymer solution for conveying the low-boiling-point polymer solution to the sampler (2). The outlet end of the gas replacement pipeline (4) is connected to the sampler (2), and the inlet end is configured to be connected to a gas source for gas replacement and pressurization of the sampler (2). The outlet end of the solvent replacement line (3) is connected to the sampling line (1), and the inlet end is configured to be connected to the solvent source for solvent replacement and pressurization of the sampling line (1). Valves are provided on the sampling line (1), the solvent replacement line (3), and the gas replacement line (4).

2. The system according to claim 1, characterized in that, The valves on the sampling line (1) include a first valve (5) at the inlet and a second valve (6) at the outlet. The outlet of the solvent replacement line (3) is connected to the sampling line (1) between the first valve (5) and the second valve (6). And / or, the valves on the solvent replacement line (3) include a third valve (7) located at the outlet end, and the valves on the gas replacement line (4) include a fourth valve (8).

3. The system according to claim 2, characterized in that, The system also includes a discharge pipeline (9), on which a fifth valve (10) is provided, and one end of the discharge pipeline (9) is connected to the sampler (2) for discharging the gas phase in the sampler (2); Preferably, one end of the discharge line (9) is connected to the gas replacement line (4) and the connection is located between the fourth valve (8) and the sampler (2).

4. The system according to any one of claims 1-3, characterized in that, The outlet end of the gas replacement line (4) is connected to the top of the sampler (2), and the outlet end of the sampling line (1) is connected to the upper middle part of the sampler (2). And / or, the design pressure and design temperature of the system are higher than the design pressure and design temperature of the container storing the low-boiling-point polymer solution; And / or, the solvent replacement line (3) is provided with a heat tracing line (11) for heating the replacement solvent in the solvent replacement line (3).

5. A method for sampling a low-boiling-point polymer solution, characterized in that, The method includes the following steps: Step (1): The replacement gas is sent into the sampler (2) through the gas replacement pipeline (4) to replace and pressurize the sampler (2). Step (2): The replacement solvent is sent into the sampling line (1) through the solvent replacement line (3) to replace and pressurize the sampling line (1); Step (3) involves introducing a low-boiling-point polymer solution into the sampler (2) via the sampling line (1). During the flow of the low-boiling-point polymer solution through the sampling line (1), the sampling line (1) is in a full liquid state. Step (4): The sampling line (1) is substituted again with a replacement solvent through the solvent replacement line (3); Step (5): Remove the polymer from the sampler (2).

6. The method according to claim 5, characterized in that, The step (1) includes: closing the second valve (6) and opening the fourth valve (8), sending the replacement gas into the sampler (2) through the gas replacement pipeline (4) to perform gas replacement and pressurization on the sampler (2), and then closing the fourth valve (8); Preferably, the pressure of the sampler (2) after pressurization is higher than the saturated vapor pressure of the replacement solvent; And / or, step (2) includes: closing the first valve (5) and the second valve (6), opening the third valve (7), sending the replacement solvent into the sampling line (1) through the solvent replacement line (3) to replace and pressurize the sampling line (1), and then closing the third valve (7); Preferably, the pressure of the sampling line (1) after pressurization is higher than the saturated vapor pressure of the replacement solvent.

7. The method according to claim 5 or 6, characterized in that, Step (3) includes: opening the first valve (5) and the second valve (6) to allow the low-boiling-point polymer solution to enter the sampler (2) through the sampling line (1), and closing the second valve (6); And / or, step (4) includes: opening the first valve (5) and the third valve (7), using the solvent replacement line (3) to replace the sampling line (1) with the replacement solvent towards the first valve (5), and closing the first valve (5) after replacement; opening the second valve (6), using the solvent replacement line (3) to replace the sampling line (1) with the replacement solvent towards the sampler (2), and closing the second valve (6) and the third valve (7) after replacement.

8. The method according to any one of claims 5-7, characterized in that, The method further includes step (3-1) between step (3) and step (4): after step (3) is completed, the fifth valve (10) is opened to discharge the gas phase in the sampler (2), and then the fifth valve (10) is closed; And / or, the method further includes performing step (4-1) between step (4) and step (5): opening the fifth valve (10) to discharge the gas phase in the sampler (2); then closing the fifth valve (10), opening the fourth valve (8), allowing the gas in the gas replacement pipeline (4) to enter the sampler (2) for pressurization, closing the fourth valve (8), opening the fifth valve (10), discharging the gas phase in the sampler (2), and completing the gas replacement.

9. The method according to any one of claims 5-8, characterized in that, The pressure of the sampling line (1) after pressurization is 0-5 MPa higher than the saturated vapor pressure of the replacement solvent, preferably 0.2-1 MPa; Preferably, the pressure of the sampler (2) after pressurization is 0-5 MPa higher than the saturated vapor pressure of the replacement solvent, preferably 0.2-1 MPa; And / or, the temperature of the replacement solvent in the solvent replacement line (3) is higher than the crystallization temperature of the polymer in the polymer solution and lower than the bubble point temperature of the replacement solvent; preferably, the temperature of the replacement solvent is more than 10°C lower than the bubble point temperature.

10. The method according to any one of claims 5-9, characterized in that, The liquid level of the polymer solution in the sampler (2) is below the connection point between the sampling line (1) and the sampler (2).

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