Falling film devolatilization device

Abstract

The invention provides a falling film type devolatilization device which comprises a vertical container, a melt pressure chamber is arranged on the upper portion of the container, a discharging chamber is arranged at the bottom of the container, the melt pressure chamber is communicated with a material inlet, the discharging chamber is provided with a material outlet, and the vertical container is provided with a heat exchange chamber between the melt pressure chamber and the discharging chamber. The devolatilization device is provided with a plurality of falling film pipes, the inner wall surfaces of the falling film pipes are material falling film flowing contact surfaces, the diameter of the inscribed circle of each falling film pipe is 50-300 mm, and the falling film pipes penetrate through the heat exchange chamber; the lower end of the falling film pipe is communicated with the blanking chamber; a circle of multiple film distribution holes are formed in the inner side of a pipe opening in the upper end of the falling film pipe in the circumferential direction, the diameter of the inscribed circle of each film distribution hole ranges from 2 mm to 15 mm, and the length-diameter ratio L / D of the length L of each film distribution hole to the diameter D of the inscribed circle ranges from 2 to 15. And the melt pressure chamber is communicated with the falling film pipe through the film distribution holes. According to the invention, the film-forming flow uniformity of materials in the equipment is good, the heat and mass transfer efficiency is high, and the internal components are compact in structure and easy to industrially amplify.

Description

Technical Field

[0001] The invention relates to falling film devolatilization equipment 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 existing research on falling film devolatilizers for such high-viscosity materials, in order to make the material continuously and evenly spread along the circumferential direction of the tube wall, the film spreading structure generally adopts an annular seam type. Although the film forming efficiency is high, it is difficult to control the liquid level during actual production. The material flow is controlled by liquid level height adjustment. In production, there are problems such as liquid level fluctuations causing material flow fluctuations, which causes changes in the residence time of the material falling film and brings about unstable quality. In addition, the film spreading effect of the annular seam type film spreading structure is greatly affected by the installation accuracy, and the uniformity of the material spreading along the tube wall is easily affected by the installation error.

[0004] At the same time, production cost is a key factor that must be considered in actual large-scale production. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above prior art and provide a falling film devolatilizer, which can make the material in the equipment have good film flow uniformity, high heat and mass transfer efficiency, compact internal component structure and easy industrial scale-up. To this end, the present invention adopts the following technical solutions: A falling film devolatilizer, comprising a vertical container, the vertical container is provided with an air extraction port and a material inlet, a melt pressure chamber is provided at the upper part of the container, a material discharge chamber is provided at the bottom of the container, the melt pressure chamber is communicated with the material inlet, and the material discharge chamber is provided with a material outlet, characterized in that: the vertical container is provided with a heat exchange chamber between the melt pressure chamber and the material discharge chamber, the devolatilizer is provided with a plurality of falling film tubes, the inner wall surface of the falling film tube is a material falling film contact surface, the diameter of the inscribed circle of the falling film tube is 50-300 mm, and the falling film tube passes through the heat exchange chamber; the lower end of the falling film tube is connected with the material discharge chamber; The bottom plate of the melt pressure chamber is provided with a plurality of connection holes for connecting the upper end of the falling film tube. A circle of a plurality of film-laying holes is arranged circumferentially on the inner side of the tube opening at the upper end of the falling film tube. The diameter of the inscribed circle of the film-laying holes is 2-15 mm. The film-laying holes connect the melt pressure chamber and the falling film tube. 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; the film holes are not connected around the inner wall of the falling film tube, the interval M between adjacent film holes is 1~20mm, and the number of film holes corresponding to each falling film tube is greater than or equal to 10.

[0006] 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, and when it 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. The special-shaped tube is preferably a regular polygonal tube or a multi-petal plum blossom tube.

[0007] The regular polygonal tubes are preferably regular quadrilaterals, regular pentagons, regular hexagons, regular heptagons, regular octagons, regular nonagons, and regular decagons; the multi-petal plum blossom tubes are preferably four-petal plum blossoms, five-petal plum blossoms, six-petal plum blossoms, seven-petal plum blossoms, eight-petal plum blossoms, nine-petal plum blossoms, and ten-petal plum blossoms.

[0008] 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 maximum inscribed circle diameter of the non-circular hole.

[0009] 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.

[0010] When the film-making hole is a circular hole or a non-circular hole, the shortest distance X from the inner wall of the film-making hole 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 of the film-making hole to have better film-forming performance on the inner wall of the falling film tube, and can be matched with the aperture of the film-making hole so that the entire melt flowing out of the film-making hole can be drawn to the inner wall of the falling film tube to form a continuous and uniform film.

[0011] Using holes to drop the film in the tube can more easily establish a full liquid stable flow, that is, it can ensure that the melt pressure chamber establishes a stable and required melt pressure. The aperture and spacing of the film-laying holes and the diameter (or circumference) of the film-laying tube can be combined to achieve uniformity in the material film-laying and falling film flow process.

[0012] The melt pressure chamber is communicated with the material inlet, and the material inlet may be directly arranged on the outer wall of the melt pressure chamber, or the melt pressure chamber is communicated with the material inlet through a pipeline.

[0013] The present invention may also adopt or combine the following further technical solutions: The length of the falling film tube is 1 to 20 m; further, the length of the falling film tube is preferably 3 to 15 m.

[0014] Each film-making hole has the same size and shape and is evenly arranged along the circumferential direction of the inner wall of the falling film tube.

[0015] The diameter of the inscribed circle of the hole in the cloth film is preferably 2-15 mm, and the aspect ratio L / D of the length L to the inscribed circle diameter D is 2-15.

[0016] Furthermore, the diameter of the inscribed circle of the cloth membrane hole is preferably 3-12 mm, and the aspect ratio is preferably 5-15.

[0017] In the container, a vacuum chamber is arranged above the melt pressure chamber, and the exhaust port is arranged in the vacuum chamber; a gas phase channel tube is arranged at the upper end of the falling film tube, the gas phase channel tube passes through the melt pressure chamber and communicates with the vacuum chamber; a film spreading ring provided with film spreading holes is connected with the gas phase channel tube, and the falling film tube and the film spreading ring are connected.

[0018] An air extraction port is arranged in the container below the heat exchange chamber and at the upper part of the material discharge chamber.

[0019] 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.

[0020] 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.

[0021] In the present invention, the material in the melt pressure chamber is continuously and evenly distributed on the inner wall of the falling film tube under the dual effects of the initial pressure and the film-distributing hole structure, and flows downward along the inner wall of the falling film tube in a film shape driven by gravity, and flows evenly under the constraint of the inner wall of the falling film tube. The volatile matter in the material continuously escapes and is extracted from the devolatilizer by the vacuum system. The material slides into the discharge chamber after falling film flow on the falling film contact surface, and is discharged from the material outlet after being stirred and homogenized.

[0022] Regarding the size design of the falling film tube, when the diameter of the inscribed circle is small, as the arrangement density increases, theoretically the surface area of ​​the tube wall per unit volume in the container is large, but the uniformity of film distribution becomes worse, and there will also be the problem of clogging of the falling film tube; when the diameter of the inscribed circle of the falling film tube is large, although the material film distribution and flow film forming effects are good, the space utilization rate of the equipment decreases and cannot meet the economic requirements of large-scale production.

[0023] The present invention utilizes a combination of a melt pressure chamber, a film spreading structure, and a falling film tube structure to match materials with different flow characteristics, thereby achieving continuous and stable film spreading of the materials on the inner wall of the falling film tube in a non-connected hole-type film spreading device, so that the residence time fluctuation of the material during the falling film flow process is small, which is beneficial to improving the quality stability of the falling film product. At the same time, it ensures the space utilization rate inside the equipment and meets the economic requirements of large-scale production. Compared with previous high-viscosity polymer devolatilizers, the present invention has a large area of ​​the falling film contact surface per unit volume of the material in the devolatilizer, a simple internal component structure, high manufacturing and installation precision, and is easy to industrialize and scale up, and is suitable for large-capacity continuous devolatilization of high-viscosity materials.

[0024] In the industrial large-scale external falling film devolatilization equipment, the volatile gas flow forms different shearing effects on the liquid film surface on different falling film tubes due to the vacuum pipeline design, which will also cause the difference in vacuum around the falling film tubes at different positions to become larger. To this end, the present invention further ensures the gas phase channel volume during the material falling film process through the falling film tube structure and vacuum pipeline design, realizes the efficient removal of a large amount of hot volatile gas during the material falling film process, ensures the high vacuum degree of the material during the whole falling film process, reduces the difference in vacuum degree during the falling film process of the material on different falling film tubes, and improves the material falling film devolatilization efficiency and the quality uniformity of the devolatilization product. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of an embodiment of a 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 film distribution hole and falling film tube combination implementation method is adopted; Figure 7 A schematic diagram of another embodiment of the falling film devolatilizer provided by the present invention; Figure 8 for Figure 7 Part of the falling film devolatilizer ( Figure 7 Center C) Enlarged view; Fig. 9 for Figure 7 N sectional view. DETAILED DESCRIPTION

[0026] 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.

[0027] Example 1, reference Figure 1 , 2 、3.

[0028] This embodiment provides a falling film devolatilizer, such as Figure 1 , 2 As shown, it adopts a vertical container, including a heat exchange chamber 5A, a melt pressure chamber 4A arranged above the heat exchange chamber 5A, a material discharge chamber 10A arranged below, and a vacuum chamber 2A above the melt pressure chamber 4A; a falling film tube 6A is vertically installed in the heat exchange chamber 5A, and a gas phase channel tube 18A is arranged at the upper end of the falling film tube 6A, and the gas phase channel tube 18A vertically passes through the melt pressure chamber 4A and communicates with the vacuum chamber 2A, and the vacuum chamber 2A is provided with a suction port 19A; a film spreading hole 15A is arranged at the intersection of the falling film tube 6A and the gas phase channel tube 18A, and the film spreading hole 15A connects the melt pressure chamber 4A and the falling film tube 6A, and the film spreading holes 15A are evenly arranged along the circumferential direction of the inner wall of the falling film tube. The film spreading ring 16A forming the film spreading hole 15A is connected to the gas phase channel tube 18A, and the falling film tube 6A is connected to the film spreading ring 16A.

[0029] The top plate 17 A of the melt pressure chamber 4 A serves as a partition between the vacuum chamber 2 A and the melt pressure chamber 4 A. The bottom plate 14 A of the melt pressure chamber 4 A 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. A material discharge chamber 10 A is provided at the bottom of the container. The falling film tube fixed bed 9 A serves as its top plate. The material discharge chamber 10 A is provided with a material outlet 11 A. A heat exchange chamber 5 A is provided between the melt pressure chamber 4 A and the material discharge chamber 10 A in the vertical container. The falling film tube 6 A passes through the heat exchange chamber 5 A, and the lower end is connected to the material discharge chamber 10 A.

[0030] 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 via flanges 3A and 8A.

[0031] 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.

[0032] The film-making hole 15 A is a hole formed by the semicircular groove on the film-making 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-making hole length L to the inscribed circle diameter D is 9, the shortest distance X from the inner wall of the film-making hole to the inner wall of the falling film tube is 0 mm, and the film-making holes are evenly arranged along the circumferential direction of the inner wall of the falling film tube, such as Figure 3 shown.

[0033] The devolatilizer is provided with a heat transfer system, including the heat exchange chamber 5 A, the heat medium inlet 7 A, and the heat medium outlet 13 A, so as to ensure the required heat for the material devolatilization process.

[0034] The bottom shell of the devolatilizer is provided with a stirrer 12A for homogenizing the material, and its stirring power is introduced from the bottom.

[0035] The devolatilizer described above is used for falling film melt polymerization to prepare high viscosity polymers. Polyethylene terephthalate (PET) melt with an intrinsic viscosity of 0.64 dL / g is used as a raw material to produce high molecular weight PET. The dynamic viscosity of the material is 320 Pa·s (temperature 280°C). The PET melt polycondensation reaction is carried out using the preferred structural scheme. The melt pressure chamber pressure is 330 kPa, and the PET intrinsic viscosity is 0.98 dL / g.

[0036] 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.

[0037] The film holes 15 A 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.

[0038] The devolatilizer described above is used for falling film melt devolatilization to prepare high-purity and high-viscosity polymers. A polyamide 6 (PA6) melt with a relative viscosity of 2.26 and a hot water extractable content of 9.20% is used as a raw material to produce PA6 with a low hot water extractable content. The dynamic viscosity of the material is 85 Pa·s (temperature 260°C). The preferred structural scheme is used for PA6 melt devolatilization, and the melt pressure chamber pressure is 150 kPa, and the PA6 relative viscosity is 2.68 and the hot water extractable content is 0.64%.

[0039] 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.

[0040] The film holes 15 A are circular holes on the film ring, with a diameter of 5 mm, a length-to-diameter ratio of the film hole length L to the inscribed circle diameter D of 10, a shortest distance X from the inner wall of the film hole to the inner wall of the falling film tube of 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.

[0041] The devolatilizer described above was used for falling film devolatilization to prepare a polymer spinning solution with low bubble content. A degassing experiment before spinning was carried out with a polyacrylonitrile (PAN)-based carbon fiber spinning solution with a viscosity-average molecular weight of 120,000. The dynamic viscosity of the material was 115 Pa·s (temperature 70°C). The optimal structural scheme was used to degas the PAN spinning solution. The pressure in the melt pressure chamber was 100 kPa. The PAN spinning solution after falling film degassing could be used for spinning experiments smoothly.

[0042] 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.

[0043] The film holes 15 A 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.

[0044] The devolatilizer described above is used for falling film melt devolatilization to prepare high-purity and high-viscosity polymers. A polyamide 6 (PA6) melt with a relative viscosity of 2.26 and a hot water extractable content of 9.20% is used as a raw material to produce PA6 with a low hot water extractable content. The dynamic viscosity of the material is 85 Pa·s (temperature 260°C). The preferred structural scheme is used for PA6 melt devolatilization. The melt pressure chamber pressure is 240 kPa, and the PA6 relative viscosity is 2.62 and the hot water extractable content is 0.94%.

[0045] 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.

[0046] The film holes 15 A 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.

[0047] The devolatilizer described above is used for preparing high-viscosity polymer by falling film melt polymerization reaction. High molecular weight PET is produced by using polyethylene terephthalate (PET) melt with an intrinsic viscosity of 0.64 dL / g as raw material. The dynamic viscosity of the material is 320 Pa·s (temperature 280°C). The PET melt polycondensation reaction is carried out by adopting the preferred structural scheme. The pressure of the melt pressure chamber is 280 kPa, and the intrinsic viscosity of PET is 1.03 dL / g.

[0048] Example 6, reference Figure 7 , 8, 9 This embodiment provides a falling film devolatilizer, such as Figure 7 ,as well as Figure 8 As shown, it adopts a vertical container, including a heat exchange chamber 5B in the middle, a melt pressure chamber 4B at the upper end of the heat exchange chamber 5B and a material discharge chamber 10B at the lower end; a falling film tube 6B is vertically installed in the heat exchange chamber 5B, and a vacuum exhaust port 19B is arranged below the heat exchange chamber 5B and located at the upper part of the material discharge chamber 10B; a film spreading hole 15B is arranged at the intersection of the falling film tube 6B and the melt pressure chamber 4B, and the film spreading hole 15B connects the melt pressure chamber 4B and the falling film tube 5B, and the film spreading holes 15B are evenly arranged along the circumferential direction of the inner wall of the falling film tube 6B. The film spreading ring 16B forming the film spreading hole 15B is connected to the falling film tube 6B, and the falling film tube 6B is connected to the bottom plate 14B of the pressure chamber.

[0049] The bottom plate 14B of the melt pressure chamber 4B is provided with a connecting hole for connecting the upper end of the falling film tube. The lower part of the falling film tube 6B is fixed on the falling film tube fixed bed 9B. A material discharge chamber 10B is provided at the bottom of the container, and the falling film tube fixed bed 9B serves as its top plate. The material discharge chamber 10B is provided with a material outlet 11B. The vertical container is provided with a heat exchange chamber 5B between the melt pressure chamber 4B and the material discharge chamber 10B. The falling film tube 6B passes through the heat exchange chamber 5B, and the lower end is connected to the material discharge chamber 10B.

[0050] 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 via a flange 8B.

[0051] 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.

[0052] The film holes 15B are circular holes on the film ring 16B, 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 Fig. 9 shown.

[0053] The devolatilizer described above is used for falling film melt devolatilization to prepare high-purity and high-viscosity polymers. A polyamide 6 (PA6) melt with a relative viscosity of 2.26 and a hot water extractable content of 9.20% is used as a raw material to produce PA6 with a low hot water extractable content. The dynamic viscosity of the material is 85 Pa·s (temperature 260°C). The PA6 melt devolatilization is carried out using the preferred structural scheme, and the melt pressure chamber pressure is 150 kPa, and the PA6 relative viscosity is 2.56 and the hot water extractable content is 1.26%.

[0054] 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 falling film devolatilizer, comprising a vertical container, wherein the container is provided with a gas extraction port and a material inlet, a melt pressure chamber is provided at the upper part of the container, a material discharge chamber is provided at the bottom of the container, the melt pressure chamber is communicated with the material inlet, and the material discharge chamber is provided with a material outlet, characterized in that: The vertical container is provided with a heat exchange chamber between the melt pressure chamber and the material discharge chamber, the devolatilizer is provided with a plurality of falling film tubes, the inner wall surface of the falling film tube is the material falling film flow contact surface, the diameter of the inscribed circle of the falling film tube is 50-300 mm, and the falling film tube passes through the heat exchange chamber; the lower end of the falling film tube is connected with the material discharge chamber; The bottom plate of the melt pressure chamber is provided with a plurality of connection holes for connecting the upper end of the falling film tube. A circle of a plurality of film-making holes is arranged circumferentially on the inner side of the tube opening at the upper end of the falling film tube. The diameter of the inscribed circle of the film-making hole is 2-15 mm, and the aspect ratio L / D of the length L of the film-making hole to the diameter D of the inscribed circle is 2-15. The film-making holes connect the melt pressure chamber and the falling film tube. 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; the film holes are not connected to each other around the inner wall of the falling film tube, the interval M between adjacent film holes is 1~20mm, and the number of film holes corresponding to each falling film tube is greater than or equal to 10.

2. The falling film devolatilizer according to claim 1, characterized in that: The falling film tube is a round tube or a special-shaped tube. When it is a round tube, the inscribed circle diameter of the falling film tube is the inner diameter of the round tube. When it 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.

3. The falling film devolatilizer according to claim 1, characterized in that: 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; the shortest distance X from the inner wall of the film hole to the inner wall of the falling film tube is less than or equal to 20 mm. 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; when the film hole is a non-circular hole, the diameter of the inscribed circle of the film hole is the maximum inscribed circle diameter of the non-circular hole.

4. The falling film devolatilizer according to claim 1, characterized in that: The falling film tube has a length of 1 to 20 m.

5. The falling film devolatilizer according to claim 1, characterized in that: Each film-making hole has the same size and shape and is evenly arranged along the circumferential direction of the inner wall of the falling film tube.

6. The falling film devolatilizer according to claim 1, characterized in that: The melt pressure of the melt pressure chamber is 10~1000kPa.

7. The falling film devolatilizer according to claim 1, characterized in that: 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.

8. The falling film devolatilizer according to claim 1, characterized in that: In the container, a vacuum chamber is arranged above the melt pressure chamber, and the exhaust port is arranged in the vacuum chamber; a gas phase channel tube is arranged at the upper end of the falling film tube, the gas phase channel tube passes through the melt pressure chamber and communicates with the vacuum chamber; a film spreading ring with film spreading holes is connected with the gas phase channel tube.

9. The falling film devolatilizer according to claim 1, characterized in that: In the vertical container, an air extraction port is arranged below the heat exchange chamber and located at the upper part of the material discharge chamber.

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