Body method PVC seed sampling device and PVC seed conversion rate measuring method

Abstract

The invention discloses a bulk method PVC seed sampling device and a PVC seed conversion rate measuring method.The bulk method PVC seed sampling device comprises a sampling tank, a water inlet main pipe and a water outlet main pipe, a sampling pipe used for being communicated with a prepolymerization kettle is arranged at the top of the sampling tank, a plunger valve is arranged at the position, close to the prepolymerization kettle, of the sampling pipe, and a sampling feeding valve is arranged at the position, close to the sampling tank, of the sampling pipe; the top of the sampling tank is provided with a vacuumizing valve and a pressure gauge used for detecting the internal pressure of the sampling tank, the sampling pipe is further communicated with a replacement pipeline and a degassing pipeline, the replacement pipeline is provided with an inflation valve, the degassing pipeline is provided with a degassing valve, an interlayer is arranged outside the sampling tank, and one end of the water inlet main pipe and one end of the water outlet main pipe are both communicated with the interlayer. A first valve and a second valve are respectively arranged on the water inlet main pipe and the water outlet main pipe. The seed sampling device is additionally arranged on an existing vinyl chloride prepolymerization kettle, conversion rate analysis and measurement are carried out on seeds, and then correction of a heat exchange value is guided.

Description

Technical Field

[0001] The invention relates to the technical field of polyethylene production, in particular to a bulk method PVC seed sampling device and a PVC seed conversion rate measuring method. Background Art

[0002] The conversion rate control of the bulk polymerization "seed" of vinyl chloride is extremely important. If the conversion rate is too low, the aggregation morphology of PVC particles is still unstable, the particle structure strength is not enough, and it is easy to be impacted by the pipe elbow and other places during the transfer process, and it will be broken and crushed, which will affect the particle characteristics of the final PVC resin obtained by post-polymerization; if the conversion rate is too high, the viscous PVC particles swollen by VCM will collide with the blades, the wall of the kettle and the baffle under the stirring action, and it is easy to adhere and adsorb to the wall of the kettle, the stirring blades and the baffles to form a sticky kettle center, which aggravates the sticky kettle of the pre-polymerization. In order to make the PVC "seed" particles have a certain cohesive force, the pre-polymerization conversion rate is generally controlled to 8% to 12%.

[0003] The existing device uses heat exchange value to control the seed conversion rate. Due to the influence of heat transfer, flow rate, temperature and other factors, the error is large and the true seed conversion rate cannot be determined. The existing device is not designed with a seed sampling device, so it is impossible to analyze the seed sampling and guide the correction of the heat exchange value. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a bulk PVC seed sampling device, which is added to the existing vinyl chloride prepolymerization reactor to analyze and measure the conversion rate of the seeds, thereby guiding the correction of the heat exchange value.

[0005] The technical solution of the present invention for solving the above technical problems is as follows: a bulk method PVC seed sampling device, comprising a sampling tank, a water inlet main pipe and a water outlet main pipe, the top of the sampling tank is provided with a sampling tube for communicating with a prepolymerization kettle, the sampling tube is provided with a plunger valve near the prepolymerization kettle, the sampling tube is provided with a sampling feed valve near the sampling tank, the top of the sampling tank is provided with a vacuum valve and a pressure gauge for detecting the internal pressure of the sampling tank, the sampling tube is also connected with a replacement pipeline and a degassing pipeline, the replacement pipeline is provided with an inflation valve, the degassing pipeline is provided with a degassing valve, the outside of the sampling tank is provided with an interlayer, one end of the water inlet main pipe and the water outlet main pipe are both connected with the interlayer, and the water inlet main pipe and the water outlet main pipe are respectively provided with a first valve and a second valve.

[0006] The beneficial effects of adopting the above technical solution are:

[0007] A seed sampling device is added to the existing vinyl chloride prepolymerization reactor to analyze and measure the conversion rate of the seeds, thereby guiding the correction of the heat exchange value.

[0008] Based on the above technical solution, the present invention can also be improved as follows.

[0009] Furthermore, an opening is provided at the top of the sampling tank, a top cover for sealing the opening is provided at the opening, the sampling tube is connected to the top cover, and the vacuum valve and the pressure gauge are connected to the top cover via a pipeline.

[0010] The beneficial effect of adopting the above further solution is that it is easy to install and disassemble the components and also easy to clean the sampling tank.

[0011] Furthermore, the top cover is connected to the opening via a flange.

[0012] The beneficial effect of adopting the above further solution is good fixing effect and easy assembly and disassembly.

[0013] Furthermore, the sampling tank is provided with a manhole.

[0014] The beneficial effect of adopting the above further solution is that it is convenient for personnel to repair equipment in a timely manner.

[0015] Furthermore, a plurality of legs are fixedly connected to the bottom of the sampling tank.

[0016] The beneficial effect of adopting the above further solution is to improve the stability of the tank body.

[0017] Furthermore, the bottom of the sampling tank is configured to be in an arc shape.

[0018] The beneficial effect of adopting the above further solution is that it is not easy to injure the human body during the movement of personnel.

[0019] Furthermore, the sampling tube is a flexible tube.

[0020] The beneficial effect of adopting the above further solution is that it is light in weight and easy for people to move.

[0021] Furthermore, it also includes a low-temperature water inlet branch pipe and a high-temperature water inlet branch pipe, one end of which is connected to the other end of the water inlet main pipe, and a third valve and a fourth valve are respectively provided on the low-temperature water inlet branch pipe and the high-temperature water inlet branch pipe.

[0022] The beneficial effect of adopting the above further solution is that the low-temperature and high-temperature water can be controlled to enter the sampling tank separately, which is convenient for operation.

[0023] Furthermore, it also includes a low-temperature water outlet branch pipe and a high-temperature water outlet branch pipe, one end of the low-temperature water outlet branch pipe and the high-temperature water outlet branch pipe are connected to the other end of the water outlet main pipe, and the low-temperature water outlet branch pipe and the high-temperature water outlet branch pipe are respectively provided with a fifth valve and a sixth valve.

[0024] The beneficial effect of adopting the above further solution is that the low-temperature and high-temperature water can be controlled to be discharged from the sampling tank separately, which is convenient for operation.

[0025] The second object of the present invention is to provide a method for measuring the conversion rate of PVC seeds, using the bulk method PVC seed sampling device, comprising the following steps:

[0026] S1: Before sampling, add hydroquinone with a mass of M0 into the sampling tank and weigh it, and mark the mass as M1. Open the first valve and the second valve and pass low-temperature cold water. Close the plunger valve, the charging valve, and the degassing valve. Open the vacuum valve, the sampling feed valve, and the pressure gauge. Vacuum the sampling tank and the sampling tube until the pressure in the sampling tank is ≤-0.086Mpa, and then close the vacuum valve.

[0027] S2: Open the plunger valve, observe the pressure in the sampling tank until it is equal to the pressure of the prepolymerization kettle, delay 10S to close the plunger valve, then close the sampling feed valve, open the degassing valve, recover the vinyl chloride in the sampling tube, then close the degassing valve, open the charging valve, replace the vinyl chloride in the sampling tube, and then close the charging valve 4, alternately recovering vinyl chloride and replacing vinyl chloride for multiple cycles. When the pressure in the sampling tank is ≤0.3Mpa, close the first valve and the second valve, remove the sampling tank, drain the water in the interlayer and weigh it, and mark the mass as M2 g;

[0028] S3: Reinstall the sampling tank, then open the degassing valve, and then slowly open the sampling feed valve. When the pressure in the sampling tank drops to ≤0.1MPa, open the first valve and the second valve and pass high-temperature hot water, close the degassing valve, and then open the vacuum valve. When the sampling tank is vacuumed to -0.086Mpa, close the degassing valve, open the inflation valve until the pressure in the sampling tank reaches 0.1MPa, close the inflation valve, open and close the degassing valve and the inflation valve alternately, cycle several times, close the first valve and the second valve, remove the sampling tank and take out the PVC seeds inside, dry and weigh them, and mark the quality as M3;

[0029] S4: Seed conversion rate C = [(M3-M0) / (M2-M1)]*100%.

[0030] Beneficial effects:

[0031] The operation steps are simple, the running cost is low, and the conversion rate of PVC seeds can be accurately measured, which is convenient for guiding the correction of heat exchange value. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of the present invention;

[0033] Figure 2 It is a working state diagram of the present invention.

[0034] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0035] 1. Vacuum valve; 2. Sampling and feeding valve; 3. Pressure gauge; 4. Inflating valve; 5. Degassing valve; 6. First valve; 7. Second valve; 8. Third valve; 9. Fourth valve; 10. Fifth valve; 11. Sixth valve; 12. Sampling tank; 13. Sampling tube; 14. Replacement pipeline; 15. Degassing pipeline; 16. Water inlet pipe; 17. Water outlet pipe. DETAILED DESCRIPTION

[0036] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0037] Embodiment 1:

[0038] like Figure 1-2 As shown, in this embodiment, a bulk method PVC seed sampling device includes a sampling tank 12, a water inlet main pipe 16 and a water outlet main pipe 17. The top of the sampling tank 12 is provided with a sampling pipe 13 for communicating with a prepolymerization kettle, the sampling pipe 13 is provided with a plunger valve near the prepolymerization kettle, the sampling pipe 13 is provided with a sampling feed valve 2 near the sampling tank 12, the top of the sampling tank 12 is provided with a vacuum valve 1 and a pressure gauge 3 for detecting the internal pressure of the sampling tank 12, the sampling pipe 13 is also connected with a displacement pipeline 14 and a degassing pipeline 15, the displacement pipeline 14 is provided with an inflation valve 4, the degassing pipeline 15 is provided with a degassing valve 5, the outside of the sampling tank 12 is provided with an interlayer, one end of the water inlet main pipe 16 and the water outlet main pipe 17 are both connected to the interlayer, and the water inlet main pipe 16 and the water outlet main pipe 17 are respectively provided with a first valve 6 and a second valve 7.

[0039] The beneficial effect of this embodiment is that a seed sampling device is added to the existing vinyl chloride prepolymerization reactor to perform seed conversion analysis and measurement, thereby guiding the correction of the heat exchange value.

[0040] When this device is used, a certain amount of hydroquinone or sodium nonylphenol or other non-volatile terminator is added and weighed before sampling, and the mass is marked as M1. g, open the first valve 6 and the second valve 7 and pass low-temperature cold water, close the plunger valve, the charging valve 4, the degassing valve 5, open the vacuum valve 1, the sampling and feeding valve 2 and the pressure gauge 3, evacuate the sampling tank 12 and the sampling tube 13 until the pressure in the sampling tank 12 is ≤-0.086Mpa, and then close the vacuum valve 1; open the plunger valve, and when the pressure in the sampling tank 12 is observed to be equal to the pressure of the prepolymerization kettle, delay 10S to close the plunger valve, and then close the sampling and feeding valve 2, open the degassing valve 5, recover the vinyl chloride in the sampling tube 13, and then close the degassing valve 5, and then open the charging valve 4 to replace the vinyl chloride in the sampling tube 13, and then close the charging valve 4 and open the degassing valve 5. Repeat this replacement cycle 3 times. When the pressure in the sampling tank 12 is ≤0.3Mpa, close the first valve 6 and the second valve 7, remove the sampling tank 12, drain the water in the interlayer and weigh it. The mass mark is M2 g; after weighing, reinstall all components, then open the degassing valve 5, and then slowly open the sampling feed valve 2. When the pressure in the sampling tank 12 drops to ≤0.1MPa, open the first valve 6 and the second valve 7 and pass high-temperature hot water, close the degassing valve 5, and then open the vacuum valve 1. When the sampling tank 12 is evacuated to -0.086Mpa, close the degassing valve 5, open the charging valve 4 until the pressure in the sampling tank 12 reaches 0.1MPa, close the charging valve 4, and then open the degassing valve 5 to evacuate the sampling tank 12. Repeat this cycle 3 times, close the first valve 6 and the second valve 7, disassemble the sampling tank 12 and take out the PVC seeds inside it, dry and weigh them, and mark the mass as M3 g; that is, the seed conversion rate C = [(M3-10) / (M2-M1)]*100%.

[0041] Among them, Figure 1 The invention discloses a pre-polymerization reactor of vinyl chloride, in which a plunger sampling valve is installed at a reserved opening in the middle of the reactor body; a nitrogen replacement pipeline 14, a degassing pipeline 15 and a valve are added to facilitate replacement before and after sampling; the water inlet pipe 16 and the water outlet pipe 17 and valves are added and connected to the sampling tank 12, and the seeds are cooled in time to terminate the reaction during the sampling stage; the sampling tank 12 is heated in the sampling stage to accelerate the removal of residual monomers; the sampling tank 12 can withstand a pressure of 2.5MPa, and the tank body volume is 500ml; the interlayer, during sampling, low-temperature water is introduced to cool the seeds and terminate the reaction in time; during the sampling stage, high-temperature hot water is introduced to volatilize the vinyl chloride monomer; the sampling port is used for seed sampling during the sampling stage and for degassing and recovering the vinyl chloride monomer during the sampling stage; the vacuum port, during the sampling stage - the sampling tank 12 and the connecting pipeline are vacuumed and then sampled; during the sampling stage - the residual monomers are vacuumed and removed; the pressure gauge 3 is used to detect the vacuum pressure and the pressure after sampling; each pipe mouth is equipped with a manual valve for easy disassembly.

[0042] Example 2

[0043] Preferably, on the basis of Example 1, the top of the sampling tank 12 is provided with an opening, and a top cover for sealing the opening is provided at the opening, the sampling tube 13 is connected to the top cover, and the vacuum valve 1 and the pressure gauge 3 are connected to the top cover through a pipeline.

[0044] The beneficial effects of this embodiment are: it is convenient to install and disassemble the components, and it is also convenient to clean the sampling tank 12.

[0045] Example 3

[0046] Preferably, based on Embodiment 2, the top cover is connected to the opening via a flange.

[0047] The beneficial effect of this embodiment is that the flange connection method has a good fixing effect and is easy to assemble and disassemble.

[0048] An alternative to Embodiment 3 is that the top cover is connected to the opening by threads or by snap-fitting to ensure a sealing effect and facilitate opening and closing of the top cover.

[0049] Example 4

[0050] Preferably, based on embodiments 1-3, a manhole is provided on the sampling tank 12.

[0051] The beneficial effect of this embodiment is that it is convenient for personnel to repair equipment in a timely manner.

[0052] Example 5

[0053] Preferably, based on embodiments 1-4, a plurality of legs are fixedly connected to the bottom of the sampling tank 12 .

[0054] The beneficial effect of this embodiment is to improve the stability of the tank body.

[0055] There are two supporting legs, which are symmetrically arranged on the bottom of the sampling tank 12 .

[0056] Example 6

[0057] Preferably, based on embodiments 1-5, the bottom of the sampling tank 12 is configured to be in an arc shape.

[0058] The beneficial effect of this embodiment is that the human body is not easily injured during the movement of personnel.

[0059] Furthermore, the bottom of the sampling tank 12 may be in a downwardly convex curved shape or a hemispherical shape.

[0060] Furthermore, the sampling tank 12 includes a top cover, a cylinder body and a lower head. The cylinder body is cylindrical and the lower head is hemispherical, which is convenient for containing materials and has good sealing performance.

[0061] Example 7

[0062] Preferably, based on Embodiments 1-6, the sampling tube 13 is a flexible tube.

[0063] The beneficial effects of this embodiment are: light weight and easy for people to move.

[0064] Furthermore, the sampling tube 13 can be made of plastic or flexible metal.

[0065] Example 8

[0066] Preferably, on the basis of Examples 1-7, a low-temperature water inlet branch pipe and a high-temperature water inlet branch pipe are further included, one end of the low-temperature water inlet branch pipe and the high-temperature water inlet branch pipe are connected to the other end of the water inlet main pipe 16, and a third valve 8 and a fourth valve 9 are respectively provided on the low-temperature water inlet branch pipe and the high-temperature water inlet branch pipe.

[0067] The beneficial effect of this embodiment is that low-temperature water and high-temperature water can be controlled to enter the sampling tank separately, and the operation is convenient.

[0068] Example 9

[0069] Preferably, on the basis of Examples 1-8, a low-temperature water outlet branch pipe and a high-temperature water outlet branch pipe are further included, one end of the low-temperature water outlet branch pipe and the high-temperature water outlet branch pipe are connected to the other end of the water outlet main pipe 17, and a fifth valve 10 and a sixth valve 11 are respectively provided on the low-temperature water outlet branch pipe and the high-temperature water outlet branch pipe.

[0070] The beneficial effect of this embodiment is that the low-temperature and high-temperature water can be controlled to be discharged from the sampling tank separately, and the operation is convenient.

[0071] It should be noted that the low-temperature cold water temperature of the low-temperature water outlet branch is 0-10°C, preferably 5°C, and the high-temperature hot water temperature of the high-temperature water outlet branch is 70-90°C, preferably 80°C.

[0072] Example 10

[0073] Preferably, based on Examples 1-9, a method for measuring PVC seed conversion rate, using the bulk method PVC seed sampling device, comprises the following steps:

[0074] S1: Before sampling, add hydroquinone with a mass of M0 into the sampling tank 12 and weigh it, and mark the mass as M1. Open the first valve 6 and the second valve 7 and pass low-temperature cold water. Close the plunger valve, the charging valve 4, and the degassing valve 5. Open the vacuum valve 1, the sampling feed valve 2 and the pressure gauge 3. Vacuum the sampling tank 12 and the sampling tube 13 until the pressure in the sampling tank 12 is ≤-0.086Mpa, and then close the vacuum valve 1;

[0075] S2: Open the plunger valve, observe the pressure in the sampling tank 12 until it is equal to the pressure of the prepolymerization kettle, delay 10S to close the plunger valve, then close the sampling feed valve 2, open the degassing valve 5, recover the vinyl chloride in the sampling tube 13, then close the degassing valve 5, open the charging valve 4, replace the vinyl chloride in the sampling tube 13, then close the charging valve 4, alternately recover the vinyl chloride and replace the vinyl chloride for multiple cycles, when the pressure in the sampling tank 12 is ≤0.3Mpa, close the first valve 6 and the second valve 7, remove the sampling tank 12, drain the water in the interlayer and weigh it, the mass is marked as M2;

[0076] S3: Reinstall the sampling tank 12, then open the degassing valve 5, and then slowly open the sampling feed valve 2. When the pressure in the sampling tank 12 drops to ≤0.1MPa, open the first valve 6 and the second valve 7 and pass high-temperature hot water, close the degassing valve 5, and then open the vacuum valve 1. When the sampling tank 12 is evacuated to -0.086Mpa, close the degassing valve 5, open the inflation valve 4 until the pressure in the sampling tank 12 reaches 0.1MPa, close the inflation valve 4, alternately open and close the degassing valve 5 and the inflation valve 4, repeat the cycle several times, close the first valve 6 and the second valve 7, remove the sampling tank 12 and take out the PVC seeds inside it, dry and weigh them, and mark the quality as M3;

[0077] S4: Seed conversion rate C = [(M3-M0) / (M2-M1)]*100%.

[0078] The beneficial effects of this embodiment are: simple operation steps, low operating cost, and the ability to accurately measure the conversion rate of PVC seeds, which is convenient for guiding the correction of heat exchange values.

[0079] Furthermore, the value of M0 can be 10±0.01g.

[0080] It should be noted that M1 weighs the sampling tank 12 plus the hydroquinone in MO, M2 weighs the sampling tank 12 plus the hydroquinone in MO and liquid vinyl chloride and solid PVC; M3 weighs the hydroquinone in MO plus solid PVC;

[0081] The number of cycles in steps S2 and S3 is performed according to a pre-set number, generally 2-4 times, preferably 3 times.

[0082] The beneficial effects of the present invention are:

[0083] A seed sampling device is added to the existing vinyl chloride prepolymerization reactor to analyze and measure the conversion rate of the seeds, thereby guiding production (correction of heat exchange value).

[0084] In the description of the present invention, it is necessary to understand that the terms "center", "length", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "inside", "outside", "peripheral", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred system or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0085] In the description of the present invention, “plurality” means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0086] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0087] 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 invention. 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.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A bulk PVC seed sampling device, characterized in that: The invention comprises a sampling tank (12), a water inlet pipe (16) and a water outlet pipe (17), wherein the top of the sampling tank (12) is provided with a sampling pipe (13) for communicating with a prepolymerization kettle, the sampling pipe (13) is provided with a plunger valve near the prepolymerization kettle, the sampling pipe (13) is provided with a sampling feed valve (2) near the sampling tank (12), the top of the sampling tank (12) is provided with a vacuum valve (1) and a pressure gauge (3) for detecting the internal pressure of the sampling tank (12), and the The sampling tube (13) is also connected to a replacement pipeline (14) and a degassing pipeline (15); the replacement pipeline (14) is provided with a gas charging valve (4); the degassing pipeline (15) is provided with a degassing valve (5); an interlayer is provided on the outside of the sampling tank (12); one end of the water inlet pipe (16) and the water outlet pipe (17) are both connected to the interlayer; the water inlet pipe (16) and the water outlet pipe (17) are respectively provided with a first valve (6) and a second valve (7).

2. The bulk PVC seed sampling device according to claim 1, characterized in that: The top of the sampling tank (12) is provided with an opening, and a top cover for sealing the opening is provided at the opening, the sampling tube (13) is connected to the top cover, and the vacuum valve (1) and the pressure gauge (3) are connected to the top cover via a pipeline.

3. A bulk PVC seed sampling device according to claim 2, characterized in that: The top cover is connected to the opening via a flange.

4. The bulk PVC seed sampling device according to claim 1, characterized in that: The sampling tank (12) is provided with a manhole.

5. The bulk PVC seed sampling device according to claim 1, characterized in that: A plurality of legs are fixedly connected to the bottom of the sampling tank (12).

6. The bulk PVC seed sampling device according to claim 1, characterized in that: The bottom of the sampling tank (12) is configured to be in an arc shape.

7. A bulk PVC seed sampling device according to any one of claims 1 to 6, characterized in that: The sampling tube (13) is a flexible tube.

8. A bulk PVC seed sampling device according to any one of claims 1 to 6, characterized in that: It also includes a low-temperature water inlet branch pipe and a high-temperature water inlet branch pipe, one end of each of which is connected to the other end of the water inlet main pipe (16), and a third valve (8) and a fourth valve (9) are provided on the low-temperature water inlet branch pipe and the high-temperature water inlet branch pipe, respectively.

9. A bulk PVC seed sampling device according to any one of claims 1 to 6, characterized in that: It also includes a low-temperature water outlet branch pipe and a high-temperature water outlet branch pipe, one end of each of the low-temperature water outlet branch pipe and the high-temperature water outlet branch pipe is connected to the other end of the water outlet main pipe (17), and a fifth valve (10) and a sixth valve (11) are respectively provided on the low-temperature water outlet branch pipe and the high-temperature water outlet branch pipe.

10. A method for measuring PVC seed conversion rate, characterized in that: The bulk method PVC seed sampling device according to any one of claims 1 to 9 comprises the following steps: S1: Before sampling, add hydroquinone with a mass of M0 into the sampling tank (12) and weigh it, and mark the mass as M1. Open the first valve (6) and the second valve (7) and introduce low-temperature cold water. Close the plunger valve, the charging valve (4), and the degassing valve (5). Open the vacuum valve (1), the sampling feed valve (2), and the pressure gauge (3). Vacuum the sampling tank (12) and the sampling tube (13) until the pressure in the sampling tank (12) is ≤-0.086Mpa, and then close the vacuum valve (1); S2: Open the plunger valve, observe the pressure in the sampling tank (12) until it is equal to the pressure of the prepolymerization kettle, delay 10S to close the plunger valve, then close the sampling feed valve (2), open the degassing valve (5), recover the vinyl chloride in the sampling tube (13), then close the degassing valve (5), open the charging valve (4), replace the vinyl chloride in the sampling tube (13), then close the charging valve (4), and alternately recover and replace the vinyl chloride for multiple cycles. When the pressure in the sampling tank (12) is ≤0.3Mpa, close the first valve (6) and the second valve (7), remove the sampling tank (12), drain the water in the interlayer and weigh it, and mark the mass as M2; S3: Reinstall the sampling tank (12), then open the degassing valve (5), and then slowly open the sampling feed valve (2). When the pressure in the sampling tank (12) drops to ≤0.1MPa, open the first valve (6) and the second valve (7) and introduce high-temperature hot water, close the degassing valve (5), and then open the vacuum valve (1). When the sampling tank (12) is evacuated to -0.086Mpa, close the degassing valve (5), open the inflation valve (4) until the pressure in the sampling tank (12) reaches 0.1MPa, close the inflation valve (4), alternately open and close the degassing valve (5) and the inflation valve (4), repeat the cycle several times, close the first valve (6) and the second valve (7), remove the sampling tank (12) and take out the PVC seeds inside, dry them and weigh them, and mark the mass as M3; S4: Seed conversion rate C = [(M3-M0) / (M2-M1)]*100%.

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