Falling film devolatilizer

Abstract

The present invention provides a falling film devolatilizer comprising a vertical container, a melt pressure chamber disposed at the upper portion of the container, and a discharge chamber disposed at the bottom of the container. The melt pressure chamber is connected to the material inlet, and the discharge chamber is provided with a material outlet. A heat exchange chamber is provided between the melt pressure chamber and the discharge chamber. The devolatilizer is provided with multiple falling film tubes, the inner wall of each tube forming the contact surface for the falling film flow of the material. The tubes have an inscribed circle diameter of 50 to 300 mm, and the tubes pass through the heat exchange chamber. The lower ends of the tubes are connected to the discharge chamber. A plurality of film distribution holes are arranged circumferentially inside the upper end openings of the tubes. The inscribed circle diameter of the holes is 2 to 15 mm, and the aspect ratio (L / D) of the hole length L to the inscribed circle diameter D is 2 to 15. The film distribution holes connect the melt pressure chamber and the falling film tubes. The present invention improves the uniformity of the material film flow within the device, enhances heat and mass transfer efficiency, and provides a compact internal component structure, making it easy to scale up industrially.

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] During the melt polymerization process, polymers such as polyethylene terephthalate (PET), polyamide 6 (PA6), polybutylene succinate (PBS), polyamide 66 (PA66), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polycarbonate (PC), and polylactic acid (PLA) inevitably produce residual small-molecule monomers or byproducts, such as ethylene glycol and water in PET and caprolactam in PA6. The solution spinning process of polyacrylonitrile and polyimide requires the removal of air bubbles from the spinning solution to ensure smooth spinning. Devolatilization is essential during the preparation of these polymer materials to remove small molecules or bubbles. This process creates extremely high dynamic viscosity, sometimes varying by orders of magnitude during the process. This makes material flow and mixing difficult and reduces heat and mass transfer efficiency.

[0003] In existing research on falling film devolatilizers for such highly viscous materials, in order to ensure continuous and uniform film distribution of the material along the circumferential direction of the tube wall, the film distribution 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. During production, liquid level fluctuations cause material flow fluctuations, which causes changes in the residence time of the falling film and brings about the problem of unstable quality. In addition, the film distribution effect of the annular seam film distribution structure is greatly affected by the installation accuracy, and the uniformity of the material distribution along the tube wall is easily affected by installation errors.

[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 present invention aims to overcome the shortcomings of the prior art by providing a falling film devolatilizer that achieves uniform film flow, high heat and mass transfer efficiency, compact internal components, and ease of industrial scale-up. To this end, the present invention employs the following technical solutions:

[0006] A falling film devolatilizer, comprising a vertical container, the vertical container being provided with an exhaust port and a material inlet, a melt pressure chamber being provided at the upper portion of the container, and a material discharge chamber being provided at the bottom portion of the container, the melt pressure chamber being connected to the material inlet, and the material discharge chamber being provided with a material outlet. The vertical container is characterized in that a heat exchange chamber is provided between the melt pressure chamber and the material discharge chamber, the devolatilizer is provided with a plurality of falling film tubes, the inner wall surfaces of the falling film tubes being contact surfaces for the falling film of the material, the inscribed circles of the falling film tubes having a diameter of 50 to 300 mm, the falling film tubes passing through the heat exchange chamber, and the lower ends of the falling film tubes being connected to the material discharge chamber.

[0007] The bottom plate of the melt pressure chamber is provided with a plurality of connection holes for connecting to the upper end of the falling film tube. A plurality of film distribution holes are arranged circumferentially inside the upper end of the falling film tube. The diameter of the inscribed circle of the film distribution holes is 2 to 15 mm. The film distribution holes connect the melt pressure chamber and the falling film tube.

[0008] When the dynamic viscosity of the material is 0.1~10Pa·s, the inscribed circle diameter of the falling film tube is 50~100mm; or, when the dynamic viscosity of the material is 10~100Pa·s, the inscribed circle diameter of the falling film tube is 60~180mm; or, when the dynamic viscosity of the material is 100~1000Pa·s, the inscribed circle diameter of the falling film tube is 80~250mm; or, when the dynamic viscosity of the material is 1000~10000Pa·s, the inscribed circle diameter 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.

[0009] 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. The special-shaped tube is preferably a regular polygonal tube or a multi-petal plum blossom tube.

[0010] 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.

[0011] The film-making hole is a circular hole or a non-circular hole or a hole formed by the groove and the inner wall of the falling film tube; when the film-making hole is a circular hole, the diameter of the inscribed circle of the film-making hole is the diameter of the circular hole; when the film-making hole is a non-circular hole, the diameter of the inscribed circle of the film-making hole is the maximum inscribed circle diameter of the non-circular hole.

[0012] 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.

[0013] When the film-forming hole is a circular hole or a non-circular hole, the shortest distance X from the inner wall of the film-forming 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-forming 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-forming hole so that the entire melt flowing out of the film-forming hole can be drawn to the inner wall of the falling film tube to form a continuous and uniform film.

[0014] Using holes to drop the film in the tube can more easily establish a full and stable flow, that is, it can ensure that the melt pressure chamber establishes a stable and required melt pressure. It can combine the aperture and spacing of the film holes and the diameter (or circumference) of the falling film tube to achieve uniformity in the material film distribution and falling film flow process.

[0015] 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.

[0016] The present invention may also adopt or combine the following further technical solutions:

[0017] 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.

[0018] Each film-making hole is of the same size and shape and is evenly distributed along the circumference of the inner wall of the falling film tube.

[0019] The diameter of the inscribed circle of the cloth membrane hole is preferably 2-15 mm, and the aspect ratio L / D of the length L to the inscribed circle diameter D is 2-15.

[0020] Furthermore, the diameter of the inscribed circle of the membrane hole is preferably 3-12 mm, and the aspect ratio is preferably 5-15.

[0021] 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 provided 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 ring with film spreading holes is connected to the gas phase channel tube, and the falling film tube and the film spreading ring are connected.

[0022] An air extraction port is provided in the container below the heat exchange chamber and at the upper part of the discharge chamber.

[0023] The heat exchange chamber is the shell side between the melt pressure chamber and the material discharge chamber, and is provided with a heat medium inlet and a heat medium outlet.

[0024] A stirrer is provided in the bottom shell of the falling film devolatilizer, that is, in the discharge chamber, for homogenizing the material after falling film devolatilization.

[0025] 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 the form of a film driven by gravity. It flows evenly under the constraint of the inner wall of the falling film tube, and 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.

[0026] Regarding the size design of the falling film tube, when the inscribed circle diameter 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 film distribution uniformity becomes worse, and the problem of falling film tube blockage will also occur; when the inscribed circle diameter 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, which cannot meet the economic requirements of large-scale production.

[0027] The present invention utilizes a combination of a melt pressure chamber, a film distribution structure, and a falling film tube structure to match materials with different flow characteristics, thereby achieving continuous and stable film distribution of the materials on the inner wall of the falling film tube in a non-connected hole-type film distribution 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 processing of high-viscosity materials.

[0028] In large-scale industrial off-tube falling film devolatilization equipment, the design of the vacuum piping causes the flow of volatile gases to exert different shearing effects on the liquid film surface on different falling film tubes, which can also cause large differences in vacuum levels around the falling film tubes at different locations. To address this issue, the present invention further ensures the volume of the gas phase channel during the falling film process, effectively removing large amounts of hot volatile gases during the falling film process, ensuring a high vacuum level throughout the entire falling film process, reducing the difference in vacuum levels between different falling film tubes, and improving the falling film devolatilization efficiency and the quality uniformity of the devolatilization products. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of an embodiment of a falling film devolatilizer provided by the present invention;

[0030] Figure 2 for Figure 1 Part of the falling film devolatilizer ( Figure 1 Center C) Enlarged image;

[0031] Figure 3 for Figure 1NN cross-sectional view of the falling film devolatilizer using the first embodiment of the combination of film holes and falling film tubes;

[0032] Figure 4 for Figure 1 NN cross-sectional view of the falling film devolatilizer using the second embodiment of the combination of film holes and falling film tubes;

[0033] Figure 5 for Figure 1 NN cross-sectional view of the falling film devolatilizer using the third combination of film holes and falling film tubes;

[0034] Figure 6 for Figure 1 NN cross-sectional view of the falling film devolatilizer using the fourth embodiment of the combination of film holes and falling film tubes;

[0035] Figure 7 This is a schematic diagram of another embodiment of the falling film devolatilizer provided by the present invention;

[0036] Figure 8 for Figure 7 Part of the falling film devolatilizer ( Figure 7 Center C) Enlarged image;

[0037] Figure 9 for Figure 7 N sectional view.

[0038] In the accompanying drawings, wherein:

[0039] 1A, material inlet; 2A, vacuum chamber; 3A, flange; 4A, melt pressure chamber; 5A, heat exchange chamber; 6A, falling film tube; 7A, heat medium inlet; 8A, flange; 9A, falling film tube fixed bed; 10A, unloading chamber; 11A, material outlet; 12A, agitator; 13A, heat medium outlet; 14A, bottom plate; 15A, film spreading hole; 16A, film spreading ring; 17A, top plate; 18A, gas phase channel tube; 19A, vacuum exhaust port;

[0040] 1B, material inlet; 4B, melt pressure chamber; 5B, heat exchange chamber; 6B, falling film tube; 7B, heat medium inlet; 8B, flange; 9B, falling film tube fixed bed; 10B, unloading chamber; 11B, material outlet; 12B, agitator; 13B, heat medium outlet; 14B, bottom plate; 15B, film distribution hole; 16B, film distribution ring; 19B, vacuum exhaust port. DETAILED DESCRIPTION

[0041] In order to deepen the understanding of the present invention, the present invention will be further described in detail with reference to the following examples. The examples are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0042] Example 1, with reference to Figure 1 、 2 、3.

[0043] This embodiment provides a falling film devolatilizer, such as Figure 1 、 2 As shown, it utilizes a vertical container comprising a heat exchange chamber 5A, a melt pressure chamber 4A above the heat exchange chamber 5A, a material discharge chamber 10A below the heat exchange chamber 5A, and a vacuum chamber 2A above the melt pressure chamber 4A. A falling film tube 6A is vertically mounted within the heat exchange chamber 5A. A gas phase passage 18A is provided at the upper end of the falling film tube 6A, vertically passing through the melt pressure chamber 4A and communicating with the vacuum chamber 2A. The vacuum chamber 2A is also provided with a gas extraction port 19A. Film distribution holes 15A are provided at the intersection of the falling film tube 6A and the gas phase passage 18A. These holes connect the melt pressure chamber 4A and the falling film tube 6A and are evenly distributed along the inner wall of the falling film tube. A film distribution ring 16A, which forms the film distribution holes 15A, is connected to the gas phase passage 18A. The falling film tube 6A and the film distribution ring 16A are connected.

[0044] 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 connection 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 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 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 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 discharge chamber 10 A.

[0045] The shell of the vertical container consists of a cylindrical main tank body, a tank top and a roughly conical tank bottom, wherein the tank top and the tank bottom are connected to the main tank body through flanges 3A and 8A.

[0046] Multiple falling film tubes are vertically installed in the devolatilizer. The falling film tubes are round tubes with an inner tangential circle diameter of 250 mm.

[0047] 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. The film-making holes are evenly arranged along the circumferential direction of the inner wall of the falling film tube, as shown in FIG. Figure 3 shown.

[0048] 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, to ensure the required heat for the material devolatilization process.

[0049] 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.

[0050] The devolatilizer described above was used to prepare a high-viscosity polymer by falling-film melt polymerization. High-molecular-weight polyethylene terephthalate (PET) melt with an intrinsic viscosity of 0.64 dL / g was used as the raw material to produce high-molecular-weight PET. The material had a dynamic viscosity of 320 Pa·s (at 280°C). Using the preferred structural scheme for PET melt polycondensation, the melt pressure chamber pressure was 330 kPa, resulting in a PET intrinsic viscosity of 0.98 dL / g.

[0051] Example 2, reference Figure 1 、 2 , 4

[0052] In this embodiment, the film-laying holes are circular holes, the falling film tubes are circular tubes, and the diameter of the inscribed circle of the falling film tubes is 150 mm.

[0053] The film holes 15A are circular holes on the film ring with a diameter of 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. The film holes are evenly arranged along the circumferential direction of the inner wall of the falling film tube, as shown in the figure. Figure 4 As shown, the rest is the same as Example 1.

[0054] The devolatilizer described above was used for falling-film melt devolatilization to prepare a high-purity, high-viscosity polymer. A polyamide 6 (PA6) melt with a relative viscosity of 2.26 and a hot-water extractable content of 9.20% was used as the raw material to produce PA6 with a low hot-water extractable content. The dynamic viscosity of the material was 85 Pa·s (at 260°C). Using the optimal structural scheme for PA6 melt devolatilization with a melt pressure chamber pressure of 150 kPa, a PA6 with a relative viscosity of 2.68 and a hot-water extractable content of 0.64% was obtained.

[0055] Example 3, reference Figure 1 、 2 , 4

[0056] In this embodiment, the film-laying holes are circular holes, the falling film tubes are circular tubes, and the diameter of the inscribed circle of the falling film tubes is 110 mm.

[0057] The film holes 15A are circular holes on the film ring with a diameter of 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. The film holes are evenly arranged along the circumference of the inner wall of the falling film tube, as shown in the figure. Figure 4 As shown, the rest is the same as Example 1.

[0058] The devolatilizer described above was used for falling film devolatilization to prepare a polymer spinning solution with a low bubble content. Pre-spinning degassing experiments were carried out using 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 for degassing the PAN spinning solution. The melt pressure chamber pressure was 100 kPa. After falling film degassing, the PAN spinning solution could be successfully used for spinning experiments.

[0059] Example 4, with reference to Figure 1 、 2 , 5

[0060] In this embodiment, the film-laying 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.

[0061] The film holes 15A are circular holes on the film ring, with a diameter of 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. The film holes are evenly arranged along the circumference of the inner wall of the falling film tube, as shown in the figure. Figure 5 As shown, the rest is the same as Example 1.

[0062] The devolatilizer described above was used to prepare a high-purity, high-viscosity polymer by falling-film melt devolatilization. A polyamide 6 (PA6) melt with a relative viscosity of 2.26 and a hot-water extractable content of 9.20% was used as the raw material to produce PA6 with a low hot-water extractable content. The dynamic viscosity of the material was 85 Pa·s (at 260°C). Using the optimal structural scheme for PA6 melt devolatilization with a melt pressure chamber pressure of 240 kPa, a PA6 with a relative viscosity of 2.62 and a hot-water extractable content of 0.94% was obtained.

[0063] Example 5, with reference to Figure 1 、 2 , 6

[0064] In this embodiment, the film-laying holes are circular holes, the falling film tubes are six-petal plum blossom tubes, and the diameter of the inscribed circle of the falling film tubes is 230 mm.

[0065] The film holes 15A 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. The film holes are evenly arranged along the circumferential direction of the inner wall of the falling film tube. Figure 6 As shown, the rest is the same as Example 1.

[0066] The devolatilizer described above was used to prepare a high-viscosity polymer by falling-film melt polymerization. High-molecular-weight polyethylene terephthalate (PET) melt with an intrinsic viscosity of 0.64 dL / g was used as the raw material to produce high-molecular-weight PET. The material had a dynamic viscosity of 320 Pa·s (at 280°C). Using the preferred structural scheme for PET melt polycondensation, the melt pressure chamber pressure was 280 kPa, resulting in a PET intrinsic viscosity of 1.03 dL / g.

[0067] Example 6, reference Figure 7 , 8, 9

[0068] This embodiment provides a falling film devolatilizer, such as Figure 7 ,as well as Figure 8 As shown, it uses 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 discharge chamber 10B at the lower end. A falling film tube 6B is vertically installed in the heat exchange chamber 5B. Below the heat exchange chamber 5B, located above the discharge chamber 10B, a vacuum exhaust port 19B is provided. Film distribution holes 15B are provided at the intersection of the falling film tube 6B and the melt pressure chamber 4B. The film distribution holes 15B connect the melt pressure chamber 4B and the falling film tube 5B and are evenly arranged along the circumference of the inner wall of the falling film tube 6B. A film distribution ring 16B forming the film distribution holes 15B is connected to the falling film tube 6B, which is then connected to the pressure chamber bottom plate 14B.

[0069] 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 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 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 discharge chamber 10. The falling film tube 6B passes through the heat exchange chamber 5B, and the lower end is connected to the discharge chamber 10B.

[0070] 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.

[0071] In this embodiment, the film-laying holes are circular holes, the falling film tubes are circular tubes, and the diameter of the inscribed circle of the falling film tubes is 150 mm.

[0072] The film holes 15B are circular holes on the film ring 16B, with a diameter of 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. The film holes are evenly arranged along the circumference of the inner wall of the falling film tube, as shown in FIG. Figure 9 shown.

[0073] The devolatilizer described above was used for falling-film melt devolatilization to prepare a high-purity, high-viscosity polymer. A polyamide 6 (PA6) melt with a relative viscosity of 2.26 and a hot-water extractable content of 9.20% was used as the raw material to produce PA6 with a low hot-water extractable content. The dynamic viscosity of the material was 85 Pa·s (at 260°C). Using the optimal structural scheme for PA6 melt devolatilization with a melt pressure chamber pressure of 150 kPa, a PA6 with a relative viscosity of 2.56 and a hot-water extractable content of 1.26% was obtained.

[0074] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. It should be noted that a person skilled in the art can make various modifications and variations without departing from the principles of the present invention, and such modifications and variations should also be considered within the scope of protection of the present invention.

Claims

1. A falling film devolatilizer comprising a vertical container, wherein the container is provided with an air extraction port and a material inlet, a melt pressure chamber is provided at the upper portion of the container, and a material discharge chamber is provided at the bottom of the container, wherein the melt pressure chamber is connected to 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 discharge chamber. The devolatilizer is provided with a plurality of falling film tubes. The inner wall surface of the falling film tube is the contact surface for the falling film flow of the material. The diameter of the inscribed circle of the falling film tube is 50-300 mm. The falling film tube passes through the heat exchange chamber. The lower end of the falling film tube is connected to the discharge chamber. The bottom plate of the melt pressure chamber is provided with a plurality of connection holes for connecting to the upper end of the falling film tube. A plurality of film distribution holes are arranged circumferentially inside the upper end of the falling film tube. The inscribed circle diameter of the film distribution holes is 2 to 15 mm, and the aspect ratio (L / D) of the length L of the film distribution holes to the inscribed circle diameter D is 2 to 15. The film distribution holes connect the melt pressure chamber and the falling film tube. When the dynamic viscosity of the material is 0.1~10Pa·s, the inscribed circle diameter of the falling film tube is 50~100mm; or, when the dynamic viscosity of the material is 10~100Pa·s, the inscribed circle diameter of the falling film tube is 60~180mm; or, when the dynamic viscosity of the material is 100~1000Pa·s, the inscribed circle diameter of the falling film tube is 80~250mm; or, when the dynamic viscosity of the material is 1000~10000Pa·s, the inscribed circle diameter 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, wherein 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, wherein The film-making 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-making hole to the inner wall of the falling film tube is less than or equal to 20 mm. When the film-making hole is a circular hole, the diameter of the inscribed circle of the film-making hole is the diameter of the circular hole; when the film-making hole is a non-circular hole, the diameter of the inscribed circle of the film-making hole is the maximum inscribed circle diameter of the non-circular hole.

4. The falling film devolatilizer according to claim 1, wherein The falling film tube has a length of 1 to 20 m.

5. The falling film devolatilizer according to claim 1, wherein Each film-making hole is of the same size and shape and is evenly distributed along the circumference of the inner wall of the falling film tube.

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

7. The falling film devolatilizer according to claim 1, wherein The heat exchange chamber is the shell side 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, wherein 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 provided 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 ring with film spreading holes is provided and the gas phase channel tube is connected together.

9. The falling film devolatilizer according to claim 1, wherein An air extraction port is provided in the vertical container below the heat exchange chamber and at the upper part of the discharge chamber.

Images