Vacuum devolatilization device

Abstract

The invention provides a vacuum devolatilization device which comprises a vertical container, the container is provided with an extraction opening and a material inlet, the upper part of the container is provided with a melt pressure chamber, and the melt pressure chamber is communicated with the material inlet; the devolatilization device is provided with at least one falling film pipe, the inner wall surface of the falling film pipe is a material falling film flowing contact surface, a vacuum chamber is arranged above the melt pressure chamber in the container, and the extraction opening is formed in the vacuum chamber; and a gas phase channel pipe is arranged at the upper end of the falling film pipe, penetrates through the melt pressure chamber and is communicated with the vacuum chamber. The vacuum-pumping effect can be improved, interference of volatile component gas on material falling film flowing is reduced, and meanwhile the inner component is compact in structure and easy to industrially amplify.

Description

Technical Field

[0001] The invention relates to a vacuum devolatilization device used in the fields of polymer devolatilization, polymer melt reaction preparation, spinning solution degassing and solution concentration, and belongs to the field of chemical production equipment. Background Art

[0002] Polyethylene terephthalate (PET), polyamide 6 (PA6), polybutylene succinate (PBS), polyamide 66 (PA66), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polycarbonate (PC), polylactic acid (PLA) and other polymers will inevitably have residual small molecular monomers or produce small molecular by-products during the melt polymerization preparation process, such as ethylene glycol and water in PET, and caprolactam in PA6. In the solution spinning process of polyacrylonitrile, polyimide, etc., it is necessary to remove the air bubbles in the spinning solution to ensure the smooth spinning. In the preparation process of such polymer materials, it is necessary to carry out the devolatilization operation to remove small molecular substances or bubbles. The dynamic viscosity of the material in this operation process is extremely high, and sometimes the dynamic viscosity of the material will change by an order of magnitude during the implementation process. The material flow and mixing are very difficult, and the heat and mass transfer efficiency is low.

[0003] In the past, for falling film devolatilization equipment, the vertical container was an extra-large space for setting up multiple falling film tubes, and a vacuum port was set on one side of the container shell for vacuuming. For falling film outside the tube, this vacuuming method will cause the following problems: the shear force formed on the liquid film surface on different falling film tubes during the flow of volatile gas is different, affecting the stability of the falling film flow of the material; and the difference in vacuum degree of falling film tubes at different positions becomes larger, affecting the quality uniformity of the falling film devolatilization product. For falling film inside the tube, during the falling film falling process from top to bottom on the falling film tube, the viscosity of the material gradually increases and the concentration of volatiles gradually decreases, making it difficult to remove the residual volatiles, and the removal efficiency of the residual volatiles will be further inhibited during the movement of a large amount of volatiles from top to bottom; and the difference in vacuum degree of falling film tubes at different positions becomes larger, affecting the quality uniformity of the falling film devolatilization product. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above prior art and provide a vacuum devolatilizer that can improve the vacuuming effect and reduce the interference of volatile gases on the falling film flow of materials. At the same time, the internal components are compact and easy to scale up industrially. To this end, the present invention adopts the following technical solutions: A vacuum devolatilizer comprises a vertical container, wherein the vertical container is provided with an exhaust port and a material inlet, a melt pressure chamber is provided at the upper part of the container, and the melt pressure chamber is communicated with the material inlet; the characteristic is that the devolatilizer is provided with at least one falling film tube, the inner wall surface of the falling film tube is the material falling film contact surface, a vacuum chamber is provided above the melt pressure chamber in the container, and the exhaust port is provided in the vacuum chamber; a gas phase channel tube is provided at the upper end of the falling film tube, the gas phase channel tube passes through the melt pressure chamber and is communicated with the vacuum chamber.

[0005] On the basis of adopting the above technical solutions, the present invention may also adopt the following further technical solutions, or use these further technical solutions in combination: The bottom plate of the melt pressure chamber is provided with a connecting hole for connecting the upper end of the falling film tube. A circle of multiple film-making holes is arranged circumferentially on the inner side of the tube mouth at the upper end of the falling film tube. The film-making holes connect the melt pressure chamber and the falling film tube. The film-making ring formed by the film-making holes is connected to the gas phase channel tube, and the falling film tube is connected to the film-making ring.

[0006] A material discharge chamber is arranged at the bottom of the container, and a material outlet is arranged in the material discharge chamber; a heat exchange chamber is arranged between the melt pressure chamber and the material discharge chamber in the vertical container, and the falling film tube passes through the heat exchange chamber, and the lower end is connected with the material discharge chamber.

[0007] The inscribed circle diameter of the falling film tube is 50-300 mm. When the falling film tube is a round tube, the inscribed circle diameter of the falling film tube is the inner diameter of the round tube. When the falling film tube is a special-shaped tube, the inscribed circle diameter of the falling film tube is the inscribed circle diameter of the inner wall of the special-shaped tube.

[0008] The special-shaped tube is preferably a regular polygonal tube or a multi-petal plum blossom tube. The regular polygonal tube is preferably a regular quadrilateral, a regular pentagon, a regular hexagon, a regular heptagon, a regular octagon, a regular nonagon, and a regular decagon. The multi-petal plum blossom tube is preferably a four-petal plum blossom, a five-petal plum blossom, a six-petal plum blossom, a seven-petal plum blossom, an eight-petal plum blossom, a nine-petal plum blossom, and a ten-petal plum blossom.

[0009] When the dynamic viscosity of the material is 0.1~10Pa·s, the diameter of the inscribed circle of the falling film tube is 50~100mm; or, when the dynamic viscosity of the material is 10~100Pa·s, the diameter of the inscribed circle of the falling film tube is 60~180mm; or, when the dynamic viscosity of the material is 100~1000Pa·s, the diameter of the inscribed circle of the falling film tube is 80~250mm; or, when the dynamic viscosity of the material is 1000~10000Pa·s, the diameter of the inscribed circle of the falling film tube is 120~300mm.

[0010] The film distribution holes are evenly arranged around the circumferential direction of the inner wall of the falling film tube, each film distribution hole is not connected to each other, the interval M between adjacent film distribution holes is 1-20mm, and the number of film distribution holes corresponding to each falling film tube is greater than or equal to 10.

[0011] The falling film tube has a length of 1 to 20 m. Further, the falling film tube has a length of preferably 3 to 12 m.

[0012] The diameter of the inscribed circle of the film hole is 2-15 mm, and the aspect ratio L / D of the length L of the film hole to the inscribed circle diameter D is 2-15. Furthermore, the diameter of the inscribed circle of the film hole is preferably 3-12 mm, and the aspect ratio is preferably 5-15; each film hole is of the same size and shape.

[0013] The film hole is a circular hole or a non-circular hole or a hole formed by a groove and the inner wall of the falling film tube; when the film hole is a circular hole, the diameter of the inscribed circle of the film hole is the diameter of the circular hole, and when the film hole is a non-circular hole, the diameter of the inscribed circle of the film hole is the diameter of the maximum inscribed circle of the non-circular hole.

[0014] The melt pressure in the melt pressure chamber is 10-1000 kPa; further, the melt pressure in the melt pressure chamber is preferably 50-600 kPa.

[0015] When the film-making holes are circular holes or non-circular holes, the shortest distance X from the inner wall of the film-making holes to the inner wall of the falling film tube is less than or equal to 20 mm, which can be matched with the hole spacing and the aspect ratio of the film-making holes so that the entire material flowing out of the film-making holes can be drawn to the inner wall of the falling film tube to form a film continuously and evenly.

[0016] The heat exchange chamber is a shell between the melt pressure chamber and the material discharge chamber, and is provided with a heat medium inlet and a heat medium outlet.

[0017] A stirrer is arranged in the bottom shell of the falling film devolatilizer, that is, in the material discharge chamber, for homogenizing the material after the falling film devolatilization.

[0018] For falling film in tube, it has its unique advantages. By designing the parameters of the film-making hole structure and the parameters of the falling film tube, it can realize the continuous and stable film-making of the flow of different flow characteristics on the inner wall of the falling film tube in the non-connected hole-type film-making device under the condition of high volume utilization (the surface area of ​​the falling film tube per unit volume), so that the residence time fluctuation of the flow of the falling film is small, which is conducive to improving the quality stability of the falling film product. It can reduce production costs and facilitate industrial scale-up.

[0019] The present invention provides a vacuuming scheme for a devolatilizer using an in-tube falling film, which can improve the vacuuming effect and reduce the interference of volatile gases on the falling film flow of materials. At the same time, the internal component structure is compact and easy to industrially scale up. The present invention ensures the volume of the gas phase channel during the falling film process of the material, realizes the efficient removal of a large amount of hot volatile gases from bottom to top during the falling film process of the material, ensures the vacuum degree of the material during the falling film process, improves the falling film devolatilization efficiency, and is suitable for large-capacity continuous devolatilization processing of high-viscosity materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the falling film devolatilizer provided by the present invention; Figure 2 for Figure 1 Part of the falling film devolatilizer ( Figure 1 Center C) Enlarged view; Figure 3 for Figure 1 NN cross-sectional view of the falling film devolatilizer when the first film distribution hole and falling film tube combination implementation method is adopted; Figure 4 for Figure 1 NN cross-sectional view of the falling film devolatilizer when the second film distribution hole and falling film tube combination implementation method is adopted; Figure 5 for Figure 1 NN cross-sectional view of the falling film devolatilizer when the third film distribution hole and falling film tube combination implementation method is adopted; Figure 6 for Figure 1 NN cross-sectional view of the falling film devolatilizer when the fourth combination of film holes and falling film tubes is adopted. DETAILED DESCRIPTION

[0021] In order to deepen the understanding of the present invention, the present invention will be further described in detail with reference to the following embodiments. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0022] Example 1, reference Figure 1 , 2 , 3 A vacuum devolatilizer provided in this embodiment, such as Figure 1 , 2 As shown, it adopts a vertical container, including a heat exchange chamber 5, a melt pressure chamber 4 arranged above the heat exchange chamber 5, a material discharge chamber 10 below the heat exchange chamber 5, and a vacuum chamber 2 above the melt pressure chamber 4; a falling film tube 6 is vertically installed in the heat exchange chamber 5, and a gas phase channel tube 18 is provided at the upper end of the falling film tube 6. The gas phase channel tube 18 vertically passes through the melt pressure chamber 4 and communicates with the vacuum chamber 2, and the vacuum chamber 2 is provided with a suction port 19; a film spreading hole 15 is provided at the intersection of the falling film tube 6 and the gas phase channel tube 18, and the film spreading hole 15 connects the melt pressure chamber 4 and the falling film tube 6, and the film spreading holes 15 are evenly arranged along the circumferential direction of the inner wall of the falling film tube. The film spreading ring 16 forming the film spreading hole 15 is connected to the gas phase channel tube 18, and the falling film tube 6 is connected to the film spreading ring 16.

[0023] The top plate 17 of the melt pressure chamber 4 serves as a partition plate between the vacuum chamber 2 and the melt pressure chamber 4. The bottom plate 14 of the melt pressure chamber 4 is provided with a connecting hole for connecting the upper end of the falling film tube. The lower part of the falling film tube is fixed on the falling film tube fixed bed 9. A material discharge chamber 10 is provided at the bottom of the container. The falling film tube fixed bed 9 serves as its top plate. The material discharge chamber 10 is provided with a material outlet 11. The vertical container is provided with a heat exchange chamber 5 between the melt pressure chamber 4 and the material discharge chamber 10. The falling film tube 6 passes through the heat exchange chamber 5, and the lower end is connected to the material discharge chamber 10.

[0024] The shell of the vertical container is composed of a cylindrical main tank body, a tank top and a substantially conical tank bottom, wherein the tank top and the tank bottom are connected to the main tank body through flanges 3 and 8 .

[0025] A plurality of falling film tubes are vertically installed in the devolatilizer. The falling film tubes are round tubes, and the diameter of the inner circle of the falling film tubes is 250 mm.

[0026] The film holes 15 are holes formed by the semicircular groove on the film ring and the inner wall of the falling film tube. The maximum inscribed circle P has a diameter of 6 mm. The aspect ratio of the film hole length L to the inscribed circle diameter D is 9. The shortest distance X from the inner wall of the film hole to the inner wall of the falling film tube is 0 mm. The film holes are evenly arranged along the circumferential direction of the inner wall of the falling film tube. Figure 3 shown.

[0027] The devolatilizer is provided with a heat transfer system, including the heat exchange chamber 5, the heat medium inlet 7, and the heat medium outlet 13, so as to ensure the required heat for the devolatilization process of the material.

[0028] The bottom shell of the devolatilizer is provided with a stirrer 12 for homogenizing the material, and its stirring power is introduced from the bottom. Example 2, reference Figure 1 , 2 , 4 In this embodiment, the film-laying holes are circular holes, the falling film tube is a circular tube, and the diameter of the inscribed circle of the falling film tube is 150 mm.

[0029] The film holes 15 are circular holes on the film ring, the diameter of the circular holes is 5 mm, the aspect ratio of the film hole length L to the inscribed circle diameter D is 12, the shortest distance X from the inner wall of the film hole to the inner wall of the falling film tube is 5 mm, and the film holes are evenly arranged along the circumferential direction of the inner wall of the falling film tube, such as Figure 4 As shown, the rest is the same as Example 1. Example 3, reference Figure 1 , 2 , 4 In this embodiment, the film-making holes are circular holes, the falling film tube is circular tube, and the diameter of the inscribed circle of the falling film tube is 110 mm.

[0030] The film holes 15 are circular holes on the film ring, the diameter of the circular holes is 5 mm, the aspect ratio of the film hole length L to the inscribed circle diameter D is 10, the shortest distance X from the inner wall of the film hole to the inner wall of the falling film tube is 4 mm, and the film holes are evenly arranged along the circumferential direction of the inner wall of the falling film tube, such as Figure 4 As shown, the rest is the same as Example 1. Example 4, reference Figure 1 , 2 , 5 In this embodiment, the film-making holes are circular holes, the falling film tubes are regular hexagonal tubes, and the diameter of the inscribed circle of the falling film tubes is 140 mm.

[0031] The film holes 15 are circular holes on the film ring, the diameter of the circular holes is 6 mm, the aspect ratio of the film hole length L to the inscribed circle diameter D is 10, the shortest distance X from the inner wall of the film hole to the inner wall of the falling film tube is 5 mm, and the film holes are evenly arranged along the circumferential direction of the inner wall of the falling film tube, such as Figure 5 As shown, the rest is the same as Example 1. Example 5, reference Figure 1 , 2 , 6 In this embodiment, the film-laying hole is a circular hole, the falling film tube is a six-petal plum blossom tube, and the diameter of the inscribed circle of the falling film tube is 230 mm.

[0032] The film holes 15 are circular holes on the film ring, the diameter of the inscribed circle of the circular hole is 6 mm, the aspect ratio of the film hole length L to the inscribed circle diameter D is 9, the shortest distance X from the inner wall of the film hole to the inner wall of the falling film tube is 3 mm, and the film holes are evenly arranged along the circumferential direction of the inner wall of the falling film tube, such as Figure 6 As shown, the rest is the same as Example 1.

[0033] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that, for ordinary technicians in this technical field, several modifications and changes can be made without departing from the principle of the present invention, and these modifications and changes should also be regarded as the protection scope of the present invention.

Claims

1. A vacuum devolatilizer, comprising a vertical container, wherein the container is provided with a vacuum port (19) and a material inlet (1), a melt pressure chamber (4) is provided at the upper part of the container, and the melt pressure chamber (4) is connected to the material inlet (1); characterized in that: The devolatilizer is provided with at least one falling film tube (6), the inner wall surface of the falling film tube (6) being the material falling film flow contact surface; in the container, a vacuum chamber (2) is provided above the melt pressure chamber (4); the exhaust port (19) is provided in the vacuum chamber (2); a gas phase channel tube (18) is provided at the upper end of the falling film tube (6), and the gas phase channel tube (18) passes through the melt pressure chamber (4) and communicates with the vacuum chamber (2).

2. The falling film devolatilizer according to claim 1, characterized in that: The bottom plate (14) of the melt pressure chamber (4) is provided with a connecting hole for connecting to the upper end of the falling film tube (6). A plurality of film-making holes (15) are arranged circumferentially on the inner side of the tube mouth of the upper end of the falling film tube (6). The film-making holes (15) connect the melt pressure chamber (4) and the falling film tube (6). The film-making ring (16) of the film-making holes (15) is connected to the gas phase channel tube (18), and the falling film tube (6) and the film-making ring (16) are connected.

3. The falling film devolatilizer according to claim 1, characterized in that: A material discharge chamber (10) is arranged at the bottom of the vertical container, and a material outlet (11) is arranged in the material discharge chamber (10); a heat exchange chamber (5) is arranged between the melt pressure chamber (4) and the material discharge chamber (10) in the vertical container, and the falling film tube (6) passes through the heat exchange chamber (5), and the lower end of the falling film tube (6) is connected to the material discharge chamber (10).

4. The falling film devolatilizer according to claim 1, characterized in that: The falling film tube (6) is a round tube or a special-shaped tube, and the diameter of the inscribed circle of the falling film tube (6) is 50-300 mm.

5. The falling film devolatilizer according to claim 2, characterized in that: The diameter of the inscribed circle of the cloth film hole is 2-15 mm, and the aspect ratio L / D of the length L of the cloth film hole to the diameter D of the inscribed circle is 2-15.

6. The falling film devolatilizer according to claim 2, characterized in that: The film-laying hole (15) is a circular hole or a non-circular hole or a hole formed by a groove and the inner wall of the falling film tube; the shortest distance X from the inner wall of the film-laying hole (15) to the inner wall of the falling film tube is less than or equal to 20 mm.

7. The falling film devolatilizer according to claim 3, characterized in that: The heat exchange chamber (5) is a shell passage between the melt pressure chamber (4) and the material discharge chamber (10), and is provided with a heat medium inlet (7) and a heat medium outlet (13).

8. The falling film devolatilizer according to claim 1, characterized in that: The melt pressure in the melt pressure chamber (4) is 10-1000 kPa.

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