Evaporator for continuous melt polymer heating falling film light component removal

Abstract

The invention provides a heating falling film light component removal evaporator for a continuous melt polymer. The heating falling film light component removal evaporator comprises a plurality of light component removal evaporators which are connected in sequence, the light component removal evaporator comprises a heater and a devolatilization device body; the bottom of the heater is communicated with the upper part of the devolatilization device body, and the upper part of the devolatilization device body is connected with the vacuum system; a grid plate internal part assembly is arranged in the devolatilization device body; a polymer passes through the heater, the polymer is molten to form a brace and enters the devolatilization device body, light components are collected through the emptying pipe at the top of the kettle and enter a vacuum system, and the polymer subjected to light component removal is obtained at the bottom of the devolatilization device body. The devolatilization device has the beneficial effects that the retention time of materials in the devolatilization device is uniformly distributed; materials enter the grid plate structure under the action of gravity, are uniformly distributed to form a film and flow into the layer-by-layer grid plates from top to bottom, and a film-forming original part is a grid plate composed of parallel angle shafts; the material has a large mass transfer specific surface area and good interface updating performance in the grid plate internal part.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer chemical equipment, and in particular relates to a continuous melt polymer heating falling film de-lighting evaporator. Background Art

[0002] In the polymer production process, removing small molecule light components such as unreacted monomers and residual solvents from the system is an essential stage of the polymerization process, and this process is called polymer de-lighting.

[0003] Existing continuous feeding polymer de-lighting systems have the following problems: low monomer removal efficiency, high proportion of reactor energy consumption, and it is easy to block pipelines or affect pumps and heat exchangers in subsequent production processes. At the same time, due to the presence of monomers, the internal cross-linking of the polymer network is insufficient, and the yield of high-quality products is reduced.

[0004] In the mass transfer process of high-viscosity material systems, special separation equipment is required, and the material is easy to block pipelines or adhere to the system.

[0005] Existing devolatilizers may form dead corners in the system, and part of the material is blocked in the pipeline, affecting the devolatilization efficiency. Summary of the Invention

[0006] In view of this, the present invention aims to provide a continuous melt polymer heating falling film de-lighting evaporator to solve at least one technical problem in the background art.

[0007] To achieve the above object, the technical solution of the present invention is realized as follows:

[0008] A continuous melt polymer heating falling film de-lighting evaporator includes a plurality of de-lighting evaporators connected in sequence;

[0009] The de-lighting evaporator includes a heater and a devolatilizer body;

[0010] The bottom of the heater is communicated with the upper part of the devolatilizer body, and the upper part of the devolatilizer body is connected to the vacuum system; a grid inner component assembly is provided inside the devolatilizer body;

[0011] The polymer passes through the heater, the polymer melts to form strips and enters the devolatilizer body, the light components are collected through the top discharge pipe of the kettle and enter the vacuum system, and the de-lighted polymer is obtained at the bottom of the devolatilizer body.

[0012] Further, a plurality of grid inner component assemblies are arranged in parallel inside the devolatilizer body, and the bottom of the devolatilizer body is communicated with the polymer outlet pipe;

[0013] A gap is left between two adjacent grid inner component assemblies up and down;

[0014] A channel is provided in the central area of the grid inner component assembly;

[0015] From top to bottom, the area of the central region channel of the grid inner component assembly decreases successively.

[0016] Furthermore, the grid inner component assembly includes a plurality of grids; the plurality of grids are sequentially connected and distributed in a polygon, and the edges of the plurality of grids enclose a polygon channel; a plurality of through holes are provided on the grids.

[0017] Preferably, each grid inner component assembly includes four sequentially connected grids; the edges of the four grids enclose a rectangular channel.

[0018] Furthermore, from top to bottom, the distribution density of the through holes on the grid inner component assembly decreases successively.

[0019] Preferably, from top to bottom, the area of the polygon region enclosed by the edges of the grids in the grid inner component assembly gradually decreases.

[0020] Preferably, in two adjacent grid inner component assemblies, the vertical projection of the edge of the grid located above is located on the corresponding grid below.

[0021] Furthermore, the grid inner component assembly is inclined, and the inclination direction is towards the central region of the grid inner component assembly.

[0022] Furthermore, the distance between adjacent grid inner component assemblies is 40 mm to 60 mm.

[0023] Preferably, the distance between the through holes of the grids of a plurality of grid inner component assemblies is 90 mm to 110 mm.

[0024] Furthermore, a polymer inlet is provided at the upper part of the devolatilizer body.

[0025] A devolatilizer jacket is sleeved on the devolatilizer body. A jacket heat transfer oil outlet is provided at the upper part of the devolatilizer jacket, and a jacket heat transfer oil inlet is provided at the lower part of the devolatilizer jacket.

[0026] Furthermore, the heater is a shell-and-tube type.

[0027] And / or, the tube arrangement mode is 58° - 62°.

[0028] And / or, the diameter of the heat exchange tubes of the heater is 18 mm to 20 mm.

[0029] The tube pitch is 24 mm to 26 mm.

[0030] And / or, baffles are provided in the shell side of the heat exchange tubes; the baffles are single-segment segmental type.

[0031] And / or the baffle spacing is 190 - 210 mm.

[0032] Preferably, a heat transfer oil outlet is provided at the upper part of the heater, and a heat transfer oil inlet is provided at the lower part of the heater.

[0033] Further, a plurality of light component discharge pipes are provided along the circumference at the upper part of the devolatilizer body, and the devolatilizer body is connected to the vacuum system through the light component discharge pipes.

[0034] Further, a distributor is arranged at the position corresponding to the polymer inlet in the devolatilizer body for distributing the polymer onto the grid plate inner component assembly located at the uppermost part;

[0035] Preferably, the split view mirror is arranged on the devolatilizer body and above the devolatilized polymer outlet.

[0036] Compared with the prior art, the continuous melt polymer heating falling film de-lighting evaporator of the present invention has the following advantages:

[0037] The residence time distribution of the material in the devolatilizer body is relatively uniform; the material enters the grid structure by gravity, is evenly distributed to form a film, and flows downward into the layers of grid plates. The film-forming element is a grid plate composed of parallel angle bars; the material has a large mass transfer specific surface area and good interface renewal performance in the grid plate inner component. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0039] Figure 1 is a schematic cross-sectional view of a continuous melt polymer heating falling film de-lighting evaporator according to an embodiment of the present invention;

[0040] Figure 2 is a cross-section of a continuous melt polymer heating falling film de-lighting evaporator according to an embodiment of the present invention.

[0041] Description of the reference numerals:

[0042] 1. Polymer inlet; 2. Heater jacket; 3. Heat transfer oil outlet; 4. Heater; 5. Heat exchange tube; 6. Devolatilizer jacket; 7. Devolatilizer body; 8. Split view mirror; 9. Grid plate inner component; 10. Polymer outlet pipe; 11. Heat transfer oil inlet; 12. Jacket heat transfer oil inlet; 13. Jacket heat transfer oil outlet; 14. Light component discharge pipe; 15. Grid plate inner component assembly. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0044] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0045] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", "connected to" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0046] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0047] Embodiment 1

[0048] A continuous melt polymer heating falling film de-lighting evaporator includes a plurality of de-lighting evaporators connected in sequence; the de-lighting evaporator includes a heater and a devolatilizer body; the bottom of the heater is communicated with the upper part of the devolatilizer body, and the upper part of the devolatilizer body is connected to a vacuum system; a grid inner component assembly is arranged inside the devolatilizer body; the polymer passes through the heater, the polymer melts to form strips and enters the devolatilizer body, the light components are collected through the top discharge pipe of the kettle and enter the vacuum system, and the polymer after de-lighting is obtained at the bottom of the devolatilizer body.

[0049] A plurality of grid inner component assemblies are arranged in parallel inside the devolatilizer body, and the bottom of the devolatilizer body is communicated with a polymer outlet pipe; there is a gap between two adjacent grid inner component assemblies up and down; a channel is arranged in the central area of the grid inner component assembly; from top to bottom, the area of the channel in the central area of the grid inner component assembly decreases in sequence.

[0050] The grid plate internals assembly includes a number of grid plates; the number of grid plates are sequentially connected and distributed in a polygon, and the edges of the number of grid plates enclose a polygon channel; a number of through holes are provided on the grid plates; each grid plate internals assembly includes four sequentially connected grid plates; the edges of the four grid plates enclose a rectangular channel.

[0051] From top to bottom, the distribution density of the through holes on the grid plate internals assembly decreases in sequence; from top to bottom, the area of the polygon region enclosed by the edges of the grid plates within the grid plate internals assembly gradually decreases; in two adjacent grid plate internals assemblies, the vertical projection of the edge of the grid plate located above is located on the corresponding grid plate below, and the grid plate internals assembly is inclined, with the inclination direction towards the central region of the grid plate internals assembly.

[0052] The distance between adjacent grid plate internals assemblies is 40 mm to 60 mm, and the spacing of the through holes of the grid plates of the number of grid plate internals assemblies is 90 mm to 110 mm. A polymer inlet is provided at the upper part of the devolatilizer body, a devolatilizer jacket is sleeved on the devolatilizer body, a jacket heat transfer oil outlet is provided at the upper part of the devolatilizer jacket, and a jacket heat transfer oil inlet is provided at the lower part of the devolatilizer jacket.

[0053] The heater is a shell-and-tube type, and the tube arrangement mode is 60°;

[0054] The diameter of the heat exchange tubes of the heater is 20 mm;

[0055] The tube pitch is 25 mm, and baffle plates are provided in the shell side of the heat exchange tubes; the baffle plates are single-segment segmental type;

[0056] The baffle plate spacing is 190 - 210 mm; a heat transfer oil outlet is provided at the upper part of the heater, and a heat transfer oil inlet is provided at the lower part of the heater.

[0057] A number of light component discharge pipes are provided along the circumference at the upper part of the devolatilizer body. The devolatilizer body is connected to the vacuum system through the light component discharge pipes. A distributor is provided at the position corresponding to the polymer inlet within the devolatilizer body for distributing the polymer onto the grid plate internals assembly located at the topmost. An access manhole is provided on the devolatilizer body and is provided above the devolatilized polymer outlet..

[0058] The materials extruded from the polymerization reactor usually contain residual small molecular weight volatile substances, such as unreacted monomers, oligomers formed after polymerization, by-products of the reaction or solvents, etc. These components will affect the quality of the final product.

[0059] The light component removal evaporator of this embodiment is used for light component removal of polylactic acid. The polylactic acid obtained from the reaction enters the heater inlet through the polymer inlet, and after heat exchange with the heat transfer oil, the polymer melt is extruded through the heat exchange tubes. Under the action of gravity, it forms a strip-shaped fluid, which gradually becomes thinner during the flow and falls onto the grid inner parts of the lower devolatilizer, forming a falling film flow. The polylactic acid stays on the grid, and the light components are removed in a vacuum environment. The material after devolatilization is collected through the bottom discharging pipe and sent to the next process, ensuring that the overall residence time of the material in the devolatilizer body is maintained at 5 minutes. The heat of the entire system is provided by a dedicated heat transfer oil mold temperature machine; the vacuum of the entire system is provided by a dedicated vacuum pump, and the light component removal effect of polylactic acid is 95%.

[0060] Example 2

[0061] This embodiment provides a continuous melt polymer heating falling film light component removal evaporator. The difference from Example 1 is that two successively connected light component removal evaporators are provided and used for light component removal in the process of polylactic acid preparation, and the light component removal effect is 99%.

[0062] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A continuous melt polymer heating falling film de-lighting evaporator, characterized in that: It includes a number of de-lighting evaporators connected in sequence; The de-lighting evaporator includes a heater and a devolatilizer body; The bottom of the heater communicates with the upper part of the devolatilizer body, and the upper part of the devolatilizer body is connected to the vacuum system; a grid plate inner component assembly is arranged inside the devolatilizer body; The polymer passes through the heater, the polymer melts to form strips and enters the devolatilizer body, the light components are collected through the top discharge pipe of the kettle and enter the vacuum system, and the polymer after de-lighting is obtained at the bottom of the devolatilizer body.

2. A continuous melt polymer heating falling film de-lighting evaporator according to claim 1, characterized in that: A number of grid plate inner component assemblies are arranged in parallel inside the devolatilizer body, and the bottom of the devolatilizer body communicates with the polymer outlet pipe; There is a gap between two adjacent grid plate inner component assemblies up and down; A channel is arranged in the central area of the grid plate inner component assembly; From top to bottom, the area of the channel in the central area of the grid plate inner component assembly decreases in sequence.

3. A continuous melt polymer heating falling film de-lighting evaporator according to claim 2, characterized in that: The grid plate inner component assembly includes a number of grid plates; a number of grid plates are connected in sequence and distributed in a polygon, and the edges of a number of grid plates enclose a polygon channel; a number of through holes are arranged on the grid plates; Preferably, each grid plate inner component assembly includes four grid plates connected in sequence; the edges of the four grid plates enclose a rectangular channel.

4. A continuous melt polymer heating falling film de-lighting evaporator according to claim 3, characterized in that: From top to bottom, the distribution density of the through holes on the grid plate inner component assembly decreases in sequence; Preferably, from top to bottom, the area of the polygon area enclosed by the edges of the grid plates in the grid plate inner component assembly gradually decreases; Preferably, in two adjacent grid plate inner component assemblies, the vertical projection of the edge of the grid plate located above is located on the corresponding grid plate below.

5. A continuous melt polymer heating falling film de-lighting evaporator according to claim 2, characterized in that: The grid plate inner component assembly is inclined, and the inclination direction is towards the central area of the grid plate inner component assembly.

6. A continuous melt polymer heating falling film de-lighting evaporator according to claim 2, characterized in that: The distance between adjacent grid plate inner component assemblies is 40mm - 60mm; Preferably, the pitch of the through holes of the grid plates of a number of grid plate inner component assemblies is 90mm - 110mm.

7. A continuous melt polymer heating falling film de-lighting evaporator according to claim 1, characterized in that: The upper part of the devolatilizer body is provided with a polymer inlet; A devolatilizer jacket is sleeved on the devolatilizer body, the upper part of the devolatilizer jacket is provided with a jacket heat transfer oil outlet, and the lower part of the devolatilizer jacket is provided with a jacket heat transfer oil inlet.

8. A continuous melt polymer heating falling film de-lighting evaporator according to claim 1, characterized in that: The heater is a shell-and-tube type; And / or, the tube arrangement method is 58° - 62°; And / or, the diameter of the heat exchange tubes of the heater is 18mm - 20mm; The tube pitch is 24mm - 26mm; And / or, baffle plates are arranged in the shell side of the heat exchange tubes; the baffle plates are single-segment segmental type; And / or the baffle plate pitch is 190 - 210mm; Preferably, the upper part of the heater is provided with a heat transfer oil outlet, and the lower part of the heater is provided with a heat transfer oil inlet.

9. A continuous melt polymer heating falling film de-lighting evaporator according to claim 1, characterized in that: A number of light component discharge pipes are arranged along the circumference on the upper part of the devolatilizer body, and the devolatilizer body is connected to the vacuum system through the light component discharge pipes.

10. A continuous melt polymer heating falling film de-lighting evaporator according to claim 7, characterized in that: A distributor is arranged at the position corresponding to the polymer inlet inside the devolatilizer body for distributing the polymer onto the grid plate inner component assembly located at the top; Preferably, an access hatch is arranged on the devolatilizer body and is arranged above the devolatilized polymer outlet.

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