A method for sampling polyester solid phase polymerization

Abstract

The present invention relates to the technical field of polyester solid phase synthesis, and discloses a polyester solid phase polymerization sampling device and a sampling method. The polyester solid phase polymerization sampling device is installed at the opening at the bottom of a reactor, and includes a driving mechanism, a material taking mechanism and a material discharging mechanism; the material taking mechanism includes a material taking pipe inserted into the opening, the upper end of the material taking pipe is provided with a valve core arranged inside the reactor, and the side wall of the material taking pipe is provided with a material taking port and a material discharging port; the material discharging mechanism includes a connecting pipe, a first valve, a vacuum pipe and a third valve connected in sequence, the vacuum pipe is connected to a vacuum pump, and the other end of the connecting pipe is connected to the opening; the driving mechanism is used to drive the material taking pipe to move, so as to realize the valve core closing or opening the opening. The present invention realizes sampling while maintaining a high vacuum and high temperature state in the reactor by balancing the internal and external pressure difference of the reactor, avoiding the air outside the reactor from entering the reactor during sampling, and ensuring the performance of the material in the reactor.

Description

Technical Field

[0001] The invention relates to the technical field of polyester solid phase synthesis, in particular to a polyester solid phase polymerization sampling method. Background Art

[0002] Polyester with high intrinsic viscosity can be used to process and shape products with high heat resistance and high mechanical strength. In order to obtain polyester with high intrinsic viscosity in polyester production, it is usually necessary to further solid phase polymerization of polyester. In order to more accurately control the reaction rate of solid phase polymerization, it is necessary to take samples of the product in the kettle at regular intervals during the reaction process to detect changes in viscosity.

[0003] Conventional solid-phase polymerization equipment is equipped with a sampling valve at the bottom of the kettle. Since solid-phase polymerization is carried out under high temperature and high vacuum conditions, the fluidity of the material is poor when sampling because the material is a solid particle and the vacuum degree in the kettle is high. At the same time, due to the high temperature in the kettle, the sampling port in the kettle may also be blocked due to the adhesion between particles during the solid-phase polymerization process. If the sampling valve is opened, it is easy to cause the material in the kettle to not flow smoothly to the sampling port, and the sample cannot be taken out. More seriously, the air outside the kettle will rapidly enter the kettle in a high vacuum state, causing the vacuum state in the kettle to be destroyed. At the same time, due to the high temperature in the kettle, the material in the kettle will immediately change color when it encounters air, causing the material to turn yellow or even burn.

[0004] Therefore, the sampling device and sampling method of the existing solid phase polymerization equipment under high vacuum state are improved to achieve a simple, easy and efficient production process for sampling in the production process. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a polyester solid phase polymerization sampling method, which avoids blockage during sampling, facilitates sampling, avoids air outside the kettle from entering the kettle during sampling, and ensures the performance of the material in the kettle.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A polyester solid phase polymerization sampling device is installed at the opening at the bottom of the reactor, and includes a driving mechanism, a material taking mechanism and a material discharging mechanism;

[0008] The material taking mechanism comprises a material taking pipe inserted into the opening, the upper end of the material taking pipe is provided with a valve core arranged inside the reactor, and the side wall of the material taking pipe is provided with a material taking port and a material discharge port;

[0009] The discharge mechanism comprises a connecting pipe, a first valve, a vacuum pipe and a third valve connected in sequence, the vacuum pipe is connected to a vacuum pump, and the other end of the connecting pipe is connected to the opening;

[0010] The driving mechanism is used to drive the material taking pipe to move, so that the valve core closes or opens the opening.

[0011] Preferably, the driving mechanism comprises a sleeve fixed on the connecting pipe and a driving rod inserted into the sleeve and threadedly connected to the sleeve, and the upper end of the driving rod is connected to the material taking pipe.

[0012] Preferably, a rotating wheel is provided at the lower end of the driving rod.

[0013] Preferably, a second valve is provided between the vacuum tube and the third valve, a cooling pipe is provided between the second valve and the third valve, and a tail pipe is provided at one end of the third valve away from the cooling pipe.

[0014] Preferably, a water inlet and a water outlet are provided on the cooling pipe, and both the water inlet and the water outlet are provided with a second control valve.

[0015] Preferably, the vacuum tube is provided with an air extraction port and an air supply port, the air extraction port is connected to a vacuum pump, and the air extraction port and the air supply port are both provided with a first control valve.

[0016] A polyester solid phase polymerization sampling method comprises the following steps:

[0017] Vacuuming: Stop the rotation of the reactor, open the first valve and the second valve, close the third valve, open the first control valve on the air extraction port, and vacuum the discharge mechanism. When the pressure in the discharge mechanism is 15-25Pa less than that of the reactor, close the second valve, and then close the air extraction port;

[0018] Feeding: Push the feeding pipe to open the valve core at the top of the feeding pipe, and ensure that the feeding port is deep into the reactor to a certain position; after rotating the reactor for 3-5 times, close the rotation of the reactor when the discharge port of the feeding pipe is directly below the bottom of the reactor;

[0019] Dropping: Open the second valve to allow part of the material in the discharge mechanism to drop into the cooling pipe, and then close the first valve;

[0020] Clean the valve core: Repeat the inching operation to start and stop the reactor several times until the particles in the connecting pipe and the particles near the valve core fall completely;

[0021] Close the valve: Turn the rotary wheel to drive the material taking pipe until the valve core completely closes the opening;

[0022] Cooling: Allow tap water to cool the cooling pipe. After cooling, close the second control valves at the water inlet and outlet at the same time.

[0023] Discharging: Open the third valve, discharge the sample particles, and test the color value change of the sample.

[0024] Preferably, cleaning the valve core comprises the following steps:

[0025] Start the reactor by jogging and make it rotate slowly, so that when the reactor stops, the discharge port of the feeding pipe is located above the opening of the reactor;

[0026] Inching the reactor forward until the discharge port of the feeding pipe is located directly above the opening of the reactor;

[0027] Inchingly reverse the reactor until the material taking pipe is level;

[0028] Repeat the above operation 3 times each, and stop when the discharge port of the feeding pipe is located above the opening of the reactor.

[0029] Preferably, the rotation of the reactor should be started before cooling, and after the reactor rotates for 3-5 cycles, the rotation of the reactor is turned off, and it is ensured that when the reactor finally stops, the discharge port of the material taking pipe is located directly below the bottom of the reactor.

[0030] Preferably, the pressure of the cooling pipe is controlled at 0.2-0.4Mpa during cooling, and the cooling time is 8-10 minutes.

[0031] The polyester solid phase polymerization sampling method of the embodiment of the present invention has the following beneficial effects compared with the prior art: by arranging a vacuum tube to connect the vacuum pump in the discharge mechanism, when sampling is required, the first valve is opened first, the third valve is closed, and the discharge mechanism is evacuated to make its pressure less than the pressure inside the reactor, and then the valve core is opened and the material taking port is connected to the inside of the reactor, and the material inside the reactor enters the discharge mechanism under the action of the pressure difference between the inside and outside of the reactor. Since the pressure difference between the inside and outside of the reactor is balanced, sampling can be achieved while maintaining the high vacuum and high temperature state in the reactor, overcoming the shortcomings of polyester particles and poor fluidity, avoiding blockage during sampling, and facilitating sampling. After the sample enters the discharge mechanism, the first valve is closed, the third valve is opened, and the valve core is closed, and then the sample in the discharge mechanism can be taken out for testing. In this process, since the opening of the reactor and the first valve are closed, the air outside the reactor is avoided from entering the reactor during sampling, thereby ensuring the performance of the material in the reactor. The present invention has a simple structure, good use effect, and is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of the polyester solid phase polymerization sampling device of the present invention.

[0033] Figure 2 This is a schematic diagram of the case where the discharge port of the feed pipe is located directly below the bottom of the reactor.

[0034] Figure 3 This is a schematic diagram of a case where the discharge port of the feed pipe is located above the bottom of the reactor.

[0035] Figure 4 This is a schematic diagram of the case where the discharge port of the feed pipe is located directly above the bottom of the reactor.

[0036] Figure 5 This is a schematic diagram of the state when the material taking pipe is horizontal.

[0037] Wherein: 1-reactor, 11-opening, 2-driving mechanism, 21-sleeve, 22-driving rod, 23-rotating wheel, 3-feeding mechanism, 31-feeding pipe, 32-valve core, 33-feeding port, 34-discharging port, 4-discharging mechanism, 42-connecting pipe, 43-first valve, 44-vacuum tube, 441-exhaust port, 442-air supply port, 45-second valve, 46-cooling pipe, 461-water outlet, 462-water inlet, 47-third valve, 48-tail pipe. DETAILED DESCRIPTION

[0038] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0039] like Figure 1 As shown, a polyester solid phase polymerization sampling device according to a preferred embodiment of the present invention is installed at an opening 11 at the bottom of a reactor 1, wherein the reactor 1 is a rotary reactor. It includes a driving mechanism 2, a material taking mechanism 3 and a material discharging mechanism 4;

[0040] The feeding mechanism 3 comprises a feeding pipe 31 inserted into the opening 11, the upper end of the feeding pipe 31 is provided with a valve core 32 arranged inside the reactor 1, and the side wall of the feeding pipe 31 is provided with a feeding port 33 and a discharge port 34, and the feeding port 33 is used to feed the reactor 1;

[0041] The discharge mechanism 4 includes a connecting pipe 42, a first valve 43, a vacuum tube 44 and a third valve 47 connected in sequence, the vacuum tube 44 is connected to a vacuum pump, and the other end of the connecting pipe 42 is connected to the opening 11; an air suction port and an air supply port are provided on the vacuum tube, the air suction port is connected to the vacuum pump, and the air suction port and the air supply port are both provided with a first control valve.

[0042] The driving mechanism 2 is used to drive the material taking pipe 31 to move, so that the valve core 32 closes or opens the opening 11 .

[0043] The polyester solid phase polymerization sampling device based on the above technical features is provided with a vacuum tube 44 connected to a vacuum pump in the discharge mechanism 4. When sampling is required, the first valve 43 is opened first, the third valve 47 is closed, and the discharge mechanism 4 is evacuated to make its pressure less than the pressure inside the reactor 1. Then the valve core 32 is opened to open the opening 11, and the material taking port 33 is connected to the inside of the reactor 1. Under the action of the pressure difference between the inside and outside of the reactor 1, the material inside the reactor 1 enters the discharge mechanism 4. Since the pressure difference between the inside and outside of the reactor 1 is balanced, sampling can be achieved while maintaining a high vacuum and high temperature state in the reactor 1, overcoming the disadvantages of polyester particles and poor fluidity, avoiding blockage during sampling, and facilitating sampling. After the sample enters the discharge mechanism 4, the first valve 43 is closed, the third valve 47 is opened, and the valve core 32 is closed to close the opening 11, and then the sample in the discharge mechanism 4 can be taken out for testing. In this process, since the opening 11 and the first valve 43 of the reactor 1 are both closed, the air outside the reactor is prevented from entering the reactor during sampling, thereby ensuring the performance of the material in the reactor. The invention has a simple structure, good use effect and is easy to promote and use.

[0044] In this embodiment, the driving mechanism 2 includes a sleeve 21 fixed on the connecting tube 42 and a driving rod 22 inserted in the sleeve 21 and threadedly connected to the sleeve 21, and the upper end of the driving rod 22 is connected to the material taking tube 31. At the same time, for easy operation, a rotating wheel 23 is provided at the lower end of the driving rod 22. When it is necessary to drive the valve core 32 to open or close the opening 11, it is only necessary to rotate the rotating wheel 23, and the rotating wheel 23 drives the driving rod 22 to rotate, so as to achieve movement along the center line direction of the sleeve 21, so that the valve core 32 is close to or away from the opening 11, and the opening 11 is opened or closed, and the operation is simple and convenient.

[0045] In this embodiment, in order to ensure a better sampling effect, a second valve 45 is provided between the vacuum tube 44 and the third valve 47, and a cooling pipe 46 is provided between the second valve 45 and the third valve 47. The cooling pipe 46 is a hollow sandwich double-layer cooling pipe, and the cooling medium is tap water. The cooling pipe 46 is provided with a water inlet 462 and a water outlet 461, and the water inlet 462 and the water outlet 461 are both provided with a second control valve. A tail pipe 48 is provided at one end of the third valve 47 away from the cooling pipe 46 for easy sampling. The first valve 43, the second valve 45 and the three valves 47 are preferably ball valves.

[0046] The vacuum tube 44 is provided with an air suction port 441 and an air replenishment port 442 . The air suction port 441 is connected to a vacuum pump. Both the air suction port 441 and the air replenishment port 442 are provided with a first control valve, so as to facilitate the inflation and replenishment of the vacuum tube 44 .

[0047] In order to solve the above technical problems, the present invention also provides a polyester solid phase polymerization sampling method. First, we need to understand that when the particles of the amorphous state of bottle-grade polyester are crystallized and solid-phase polymerized in a solid phase polymerization reactor, the two processes are carried out in sequence, and the specific operation steps are as follows: the initial intrinsic viscosity is 0.5-0.7dL / g, the final intrinsic viscosity is 1.0-1.2dL / g, crystallization is carried out at 140°C, solid phase polymerization is carried out at 230°C, and after crystallization for 2h, solid phase polymerization for 10h, and solid phase polymerization for 20h, the particles in the reactor are sampled and checked for color changes.

[0048] The sampling method of the present invention adopts the above-mentioned polyester solid phase polymerization sampling device to perform sampling, and comprises the following steps:

[0049] Vacuuming: Stop the rotation of the reactor 1, open the first valve 43 and the second valve 45, close the third valve 47, open the first control valve on the air pumping port 441, and vacuum the discharge mechanism 4. When the pressure in the discharge mechanism 4 is less than 15-25Pa (preferably 20Pa) of the reactor, close the second valve 45, and then close the first control valve on the air pumping port 441;

[0050] Taking out the material: The driving rod 22 is controlled by the rotating wheel 23 to push the taking out tube 31, so that the valve core 32 at the top of the taking out tube 31 is opened, and the taking out port 33 is ensured to extend into a certain position in the reactor; after rotating the reactor for 3-5 times, the discharge port 34 of the taking out tube 31 is located directly below the bottom of the reactor (such as Figure 2 ) turning off the rotation of the reaction kettle 1;

[0051] Dropping: Open the second valve 45 to allow part of the material in the discharge mechanism 4 to drop into the cooling pipe 46, and then close the first valve 43;

[0052] Clean the valve core: Repeat the step of starting and stopping the reactor 1 several times until the particles in the connecting pipe 42 and the particles near the valve core 32 completely fall down, so as to prevent the residual particles from causing the valve core 32 to not close tightly. It specifically includes the following steps:

[0053] The reactor 1 is started by jogging and rotated slowly, so that when the reactor 1 stops, the discharge port 34 of the feeding pipe 31 is located above the opening 11 of the reactor 1 (such as Figure 3 );

[0054] Then, the reactor 1 is rotated forward until the discharge port 34 of the feeding pipe 31 is located directly above the opening 11 of the reactor 1 (eg Figure 4 );

[0055] Instantly reverse the reactor 1 until the feed pipe 31 is level (such as Figure 5 );

[0056] Repeat the above operation 3 times each, and finally make the discharge port 34 of the material taking pipe 31 located above the opening 11 of the reactor 1 (such as Figure 3 )stop.

[0057] Valve closing: Turn the rotating wheel 23 to drive the material taking pipe 31 until the valve core 32 completely closes the opening 11;

[0058] Cooling: Tap water is introduced into the cooling pipe 46 for cooling. After cooling, the second control valves of the water inlet 462 and the water outlet 461 are closed simultaneously.

[0059] Before cooling, the reaction kettle 1 needs to be turned on and rotated for 3-5 cycles, then the reaction kettle 1 is turned off and the discharge port 34 of the feeding pipe 31 is located directly below the bottom of the reaction kettle 1 when the reaction kettle 1 finally stops (e.g. Figure 2 ).

[0060] The pressure of the cooling pipe is controlled at 0.2-0.4Mpa during cooling, and the cooling time is 8-10 minutes.

[0061] Discharging: Open the third valve 47, discharge the sample particles, and test the color value change of the sample.

[0062] Evaluation test: The color value of the sample was tested using an X-Rite Ci7600 spectrophotometer according to the standard, as shown in the following table.

[0063] Data description:

[0064]

[0065] From the above data, it can be seen that the color data of the samples tested can truly reflect the color change state of polyester during the viscosity increase process.

[0066] In the present invention, by balancing the pressure difference between the inside and outside of the reactor 1, sampling can be achieved while maintaining a high vacuum and high temperature state in the reactor 1, thereby avoiding the change in the color of the polyester caused by the air outside the reactor 1 entering the high vacuum reactor 1.

[0067] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A method for sampling polyester solid phase polymerization, Features: The polyester solid phase polymerization sampling device is used for sampling. The polyester solid phase polymerization sampling device is installed at the opening at the bottom of the reactor and includes a driving mechanism, a material taking mechanism and a material discharging mechanism. The material taking mechanism comprises a material taking pipe inserted into the opening, the upper end of the material taking pipe is provided with a valve core arranged inside the reactor, and the side wall of the material taking pipe is provided with a material taking port and a material discharge port; The discharge mechanism comprises a connecting pipe, a first valve, a vacuum pipe and a third valve connected in sequence, the vacuum pipe is connected to a vacuum pump, and the other end of the connecting pipe is connected to the opening; The driving mechanism is used to drive the material taking pipe to move, so that the valve core closes or opens the opening; A second valve is provided between the vacuum tube and the third valve, a cooling pipe is provided between the second valve and the third valve, and a tail pipe is provided at one end of the third valve away from the cooling pipe; The vacuum tube is provided with an air extraction port and an air supply port, the air extraction port is connected to a vacuum pump, and the air extraction port and the air supply port are both provided with a first control valve; The sampling method includes the following steps: Vacuuming: Stop the rotation of the reactor, open the first valve and the second valve, close the third valve, open the first control valve on the air extraction port, and vacuum the discharge mechanism. When the pressure in the discharge mechanism is 15-25Pa less than that of the reactor, close the second valve, and then close the air extraction port; Feeding: Push the feeding pipe to open the valve core at the top of the feeding pipe, and ensure that the feeding port is deep into the reactor to a certain position; after rotating the reactor for 3-5 times, close the rotation of the reactor when the discharge port of the feeding pipe is directly below the bottom of the reactor; Dropping: Open the second valve to allow part of the material in the discharge mechanism to drop into the cooling pipe, and then close the first valve; Clean the valve core: Repeat the inching operation to start and stop the reactor several times until the particles in the connecting pipe and the particles near the valve core fall completely; Close the valve: Turn the rotary wheel to drive the material taking pipe until the valve core completely closes the opening; Cooling: Let tap water flow into the cooling pipe for cooling. After cooling, close the second control valves at the water inlet and outlet at the same time; Discharging: Open the third valve, discharge the sample particles, and test the color value change of the sample.

2. The polyester solid phase polymerization sampling method according to claim 1, Features: Cleaning the valve core involves the following steps: Start the reactor by jogging and make it rotate slowly, so that when the reactor stops, the discharge port of the feeding pipe is located above the opening of the reactor; Inching the reactor forward until the discharge port of the feeding pipe is located directly above the opening of the reactor; Inchingly reverse the reactor until the material taking pipe is level; Repeat the above operation 3 times each, and stop when the discharge port of the feeding pipe is located above the opening of the reactor.

3. The polyester solid phase polymerization sampling method according to claim 1, Features: Before cooling, the rotation of the reactor must be turned on. After the reactor rotates for 3-5 cycles, the rotation of the reactor must be turned off, and it must be ensured that when the reactor finally stops, the discharge port of the feed pipe is located directly below the bottom of the reactor.

4. The polyester solid phase polymerization sampling method according to claim 1, Features: The pressure of the cooling pipe is controlled at 0.2-0.4Mpa during cooling, and the cooling time is 8-10 minutes.

5. The polyester solid phase polymerization sampling method according to claim 1, Features: The driving mechanism comprises a sleeve fixed on the connecting pipe and a driving rod inserted in the sleeve and threadedly connected to the sleeve, and the upper end of the driving rod is connected to the material taking pipe.

6. The polyester solid phase polymerization sampling method according to claim 5, Features: A rotating wheel is arranged at the lower end of the driving rod.

7. The polyester solid phase polymerization sampling method according to claim 1, Features: The cooling pipe is provided with a water inlet and a water outlet, and the water inlet and the water outlet are both provided with a second control valve.

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