Polypropylene carbonate granule conveying device and method
The polypropylene carbonate granule conveying device, designed with a low-temperature air supply unit and precise control valves, solves the problems of adhesion and performance degradation caused by frictional heating during traditional pneumatic conveying, and achieves efficient and stable granule conveying.
Patent Information
- Application Number
- CN202511927132.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-19
- Publication Date
- 2026-02-10
AI Technical Summary
In traditional pneumatic conveying processes, polypropylene carbonate granules tend to adhere to the inner wall of the pipe and agglomerate due to frictional heating, which affects production efficiency and reduces product qualification rate.
It adopts a low-temperature air supply unit and a precise control valve design, combined with an elbow structure, to transport and control the air volume and material volume using low-temperature cold air, avoiding friction heating and particle collision, and improving the conveying effect through mixing, purification and degassing.
It effectively avoids material adhesion and particle damage, maintains stable particle performance, improves conveying efficiency and product qualification rate, and reduces the risk of pipeline blockage.
Smart Images
Figure CN121493330A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of polypropylene carbonate production, and particularly relates to a polypropylene carbonate granular material conveying device and method. BACKGROUND
[0002] Polypropylene carbonate (PPC for short) is an environmentally friendly biodegradable polymer material, and is increasingly widely applied in the fields of packaging, injection molding, etc. In the industrialized production of polypropylene carbonate, the conveying link of granular material is a key process for connecting granulation, storage and processing. At present, the traditional air conveying process is mostly used for conveying granular material in the industry, that is, normal temperature air is used as the conveying medium.
[0003] However, the molecular chain of polypropylene carbonate granular material has strong polarity and poor heat resistance. In the traditional air conveying process, the high-speed friction between the granular material and the inner wall of the pipeline and between the granular materials can generate significant heat, causing the local temperature in the air conveying pipeline to rise to above 40 DEG C, which exceeds the glass transition temperature of polypropylene carbonate, and further causes the surface of the granular material to soften and the adhesion to increase, resulting in problems such as adhesion to the inner wall of the pipeline and agglomeration and adhesion of the granular material, and even causing the pipeline to be blocked and affecting the production efficiency in severe cases. Meanwhile, the frictional heating can also cause the mechanical properties of the polypropylene carbonate granular material to deteriorate, reducing the product pass rate.
[0004] Therefore, it is urgent to solve the problem of conveying polypropylene carbonate granular material. SUMMARY
[0005] The polypropylene carbonate granular material conveying device and method provided by the application uses low-temperature air conveying, which can avoid material adhesion, reduce collision damage and ensure the performance stability of PPC granular material.
[0006] The technical scheme of the application comprises: a polypropylene carbonate granular material conveying device, comprising: a buffer hopper, a first plug valve, a first rotary valve and a first valve are arranged on the discharge pipeline of the buffer hopper; a blending bin, a first inlet of the blending bin is communicated with the discharge pipeline of the buffer hopper through a blending feeding pipeline, a second inlet of the blending bin is connected with an internal circulation pipeline, the internal circulation pipeline is communicated with a discharge pipeline of the blending bin, and the discharge pipeline of the blending bin is provided with a second plug valve and a second rotary valve; an elutriator, an inlet of the elutriator is connected with an elutriation feeding pipeline, and the elutriation feeding pipeline is communicated with the discharge pipeline of the blending bin; a packaging bin, an inlet of the packaging bin is communicated with an outlet of the elutriator through a pipeline; and a low-temperature air supply unit, the low-temperature air supply unit comprises a compressor and a heat exchanger communicated with the compressor, low-temperature cold air is formed after the air conveyed by the compressor is heat-exchanged in the heat exchanger, and the low-temperature cold air is communicated with the blending feeding pipeline, the internal circulation pipeline and the elutriation feeding pipeline.
[0007] Preferably, a bend structure is arranged at the corner of the blending feeding pipeline, the internal circulation pipeline and the elutriation feeding pipeline.
[0008] Preferably, the bend structure comprises straight pipe sections arranged at two ends and a transition section connecting the straight pipe sections at the two ends, the straight pipe sections at the two ends are perpendicular, and the outer wall of the transition section is provided with a bevel.
[0009] Preferably, the two ends of the bevel are connected with the outer wall of the straight pipe section, and the inclination angle of the bevel is 40-50°.
[0010] Preferably, the blending feeding pipeline is provided with a blending feeding shoe, the first interface of the blending feeding shoe is connected with the discharge pipeline of the buffer hopper, the second interface of the blending feeding shoe is connected with the low-temperature cold air, and the third interface of the blending feeding shoe is connected with the blending feeding pipeline.
[0011] Preferably, the internal circulation pipeline is provided with an internal circulation feeding shoe, the first interface of the internal circulation feeding shoe is connected with the discharge pipeline of the blending bin, the second interface of the internal circulation feeding shoe is connected with the low-temperature cold air, and the third interface of the internal circulation feeding shoe is connected with the internal circulation pipeline.
[0012] Preferably, the elutriation feeding pipeline is provided with an elutriation feeding shoe, the first interface of the elutriation feeding shoe is connected with the discharge pipeline of the blending bin, the second interface of the elutriation feeding shoe is connected with the low-temperature cold air, and the third interface of the elutriation feeding shoe is connected with the elutriation feeding pipeline.
[0013] Preferably, the blending feeding pipeline and the elutriation feeding pipeline are provided with a reversing valve, the discharge pipeline of the blending bin comprises a first branch discharge pipeline and a second branch discharge pipeline, the first branch discharge pipeline is connected with the internal circulation pipeline, the second branch discharge pipeline is connected with the elutriation feeding pipeline, and the first branch discharge pipeline and the second branch discharge pipeline are provided with a reversing valve.
[0014] Preferably, the heat exchanger is connected with a low-temperature water inlet pipe and a low-temperature water outlet pipe, and the water temperature in the low-temperature water outlet pipe is not higher than 10℃.
[0015] The application further provides a polypropylene carbonate granular material conveying method comprising the polypropylene carbonate granular material conveying device, and the conveying step of the polypropylene carbonate granular material comprises: synchronously adjusting the first plug valve and the first rotary valve of the buffer hopper discharge pipeline to control the discharge load of the polypropylene carbonate granular material in the buffer hopper; conveying the polypropylene carbonate granular material discharged from the buffer hopper to the blending material bin through the blending feeding pipeline by using the low-temperature cold air formed by the low-temperature air supply unit; synchronously adjusting the second plug valve and the second rotary valve of the blending material bin discharge pipeline to control the discharge load of the polypropylene carbonate granular material in the blending material bin, and conveying the polypropylene carbonate granular material discharged from the blending material bin into the blending material bin through the inner circulation pipeline by using the low-temperature cold air, so that the polypropylene carbonate granular material is self-blended and degassed and purified; synchronously adjusting the second plug valve and the second rotary valve of the blending material bin discharge pipeline to control the discharge load of the polypropylene carbonate granular material in the blending material bin, and conveying the polypropylene carbonate granular material discharged from the blending material bin into the elutriation device through the elutriation feeding pipeline by using the low-temperature cold air, so that the polypropylene carbonate granular material is dust-removing and purified in the elutriation device, and the polypropylene carbonate granular material after dust-removing and purification is discharged from the elutriation device and enters the packaging material bin.
[0016] The application has the following beneficial effects: the low-temperature air supply unit is designed, the heat exchanger is used to cool the air conveyed by the compressor to form low-temperature cold air for conveying the PPC granular material, so that the problem of material adhesion caused by the temperature rise of the PPC granular material conveyed by normal-temperature air can be avoided; meanwhile, the first plug valve, the first rotary valve and the first valve are designed in the discharge pipeline of the buffer hopper, the discharge load of the PPC granular material in the buffer hopper is controlled by using the first plug valve and the first rotary valve, the feeding amount and the air volume of the low-temperature cold air can be coordinated, so that the PPC granular material can be prevented from being damaged due to excessive collision between the PPC granular materials in the cold air feeding, and the problem of performance reduction of the PPC granular material caused by the collision damage of the granular materials can be avoided; meanwhile, the blending material bin and the elutriation device are designed to self-blend, degas and purify and dust-removing and purify the PPC granular material, the inner circulation pipeline is designed in the blending material bin, the elutriation feeding pipeline is designed in the blending material bin and the elutriation device, the inner circulation pipeline and the elutriation feeding pipeline are connected with the low-temperature cold air, and the low-temperature cold air is also used for conveying during the self-blending, degas and purification and dust-removing and purification of the PPC granular material, so that the conveying effect of the conveying device on the PPC granular material can be improved. BRIEF DESCRIPTION OF DRAWINGS
[0017] In order to make the technical scheme of the embodiments of the present application clearer, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some of the embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.
[0018] Figure 1 is a schematic diagram of the embodiment;
[0019] Figure 2 is a schematic diagram of the elbow structure of the embodiment.
[0020] wherein:
[0021] 1, vibrating screen, 2, buffer hopper, 21, first flapper valve, 22, first rotary valve, 23, first valve, 3, blending feeding pipeline, 31, blending feeding shoe, 4, blending material bin, 41, second flapper valve, 42, second rotary valve, 5, internal circulation pipeline, 51, internal circulation feeding shoe, 52, internal circulation valve, 6, elutriation feeding pipeline, 61, elutriation feeding shoe, 62, elutriation valve, 7, elutriator, 71, third rotary valve, 8, packaging material bin, 9, compressor, 10, heat exchanger, 11, low-temperature water inlet pipe, 12, low-temperature water outlet pipe, 20, reversing valve, 30, elbow structure, 301, swash plate. DETAILED DESCRIPTION
[0022] In order to make the technical scheme of the embodiments of the present application clearer, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some of the embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.
[0023] In this document, the terms "upper", "lower", "left", "right", "inner", "outer" and the like are established based on the positional relationship shown in the drawings, and the corresponding positional relationship may also change accordingly according to the different drawings, therefore, they cannot be understood as absolute limitations on the scope of protection; moreover, the relationship terms such as "first" and "second" are only used to distinguish one part from another part with the same name, and do not necessarily require or imply any such actual relationship or order between the parts. In addition, in the embodiments of the present application, "above", "below" and the like include the number.
[0024] The PPC granular material conveying device and method of the embodiment pay attention to the fact that the existing PPC granular material is mostly conveyed at room temperature, but the room temperature conveying is prone to cause the pipe to heat up due to friction heating during the conveying of the PPC granular material, and then cause the problem of adhesion of the PPC granular material due to the heating. In view of this, the embodiment seeks a solution to realize that the PPC granular material will not be adhered during conveying, and avoid the performance reduction of the PPC granular material caused by the adhesion of the material.
[0025] It is also noted that low-temperature pneumatic conveying processes are currently used in the conveying of heat-sensitive granular materials such as ethylene-vinyl acetate copolymer (EVA). However, PPC and EVA have many differences. For example, their molecular structures, heat resistance, and surface properties are significantly different. PPC is more polar and has a lower softening temperature. If the low-temperature pneumatic conveying process for EVA is directly applied, the problems of adhesion and low efficiency in conveying PPC granules will still not be solved.
[0026] Based on the above practical difficulties, this embodiment provides a conveying device and method for PPC granules.
[0027] On the one hand, this embodiment provides a polypropylene carbonate granule conveying device.
[0028] Reference Figure 1 and Figure 2 The polypropylene carbonate granule conveying device of this embodiment includes a buffer hopper 2, a mixing hopper 4, a washing machine 7, a packaging hopper 8, and a low-temperature air supply unit.
[0029] The discharge pipeline of the buffer hopper 2 is equipped with a first gate valve 21, a first rotary valve 22, and a first valve 23. By designing the first gate valve 21 and the first rotary valve 22 in the discharge pipeline of the buffer hopper 2, the discharge load of the PPC granules in the buffer hopper 2 can be precisely controlled by adjusting both synchronously. This facilitates coordination with the low-temperature cold air volume used for conveying the granules, avoiding damage caused by excessive collisions during conveying due to excessive air volume, and also avoiding insufficient conveying power due to insufficient air volume. Specifically, the first gate valve 21, the first rotary valve 22, and the first valve 23 can adopt conventional valve structures. The specific valve structure is not the focus of improvement in this embodiment and will not be elaborated here.
[0030] The first inlet of the blending silo 4 is connected to the discharge pipeline of the buffer hopper 2 via the blending feed pipeline 3, thereby conveying the PPC granules discharged from the buffer hopper 2 to the blending silo 4 through the blending feed pipeline 3. The second inlet of the blending silo 4 is connected to an internal circulation pipeline 5, which is connected to the discharge pipeline of the blending silo 4. That is, the blending silo 4 is also designed with an internal circulation pipeline 5, which allows the PPC granules discharged from the blending silo 4 to re-enter the blending silo 4, thereby achieving self-blending and purification degassing of the PPC granules and improving the uniformity and quality of the PPC granules. The discharge pipeline of the mixing silo 4 is designed with a second gate valve 41 and a second rotary valve 42. The synchronous adjustment of the two can accurately control the discharge load of the PPC granules discharged from the mixing silo 4, so as to improve the coordination with the air volume of the low temperature cold air conveying it, so as to avoid damage caused by excessive collision of PPC granules during conveying due to excessive air volume, and also to avoid insufficient conveying power of PPC granules due to insufficient air volume.
[0031] The inlet of the washing machine 7 is connected to a washing and feeding pipeline 6, which is connected to the outlet pipeline of the mixing silo 4. This allows the PPC granules discharged from the mixing silo 4 to be transported to the washing machine 7 via the washing and feeding pipeline 6. The washing machine 7 performs dust removal and purification on the PPC granules. The inlet of the packaging silo 8 is connected to the outlet of the washing machine 7 via a pipeline, allowing the dust-removed and purified PPC granules to be transported to the packaging silo 8 for storage, awaiting subsequent packaging and storage.
[0032] The low-temperature air supply unit includes a compressor 9 and a heat exchanger 10 connected to the compressor 9. The air supplied by the compressor is heated in the heat exchanger 10 to form low-temperature cold air. This low-temperature cold air is connected to the blending feed line 3, the internal circulation line 5, and the washing feed line 6. This allows for the use of low-temperature cold air to transport PPC granules. Low-temperature cold air is used in multiple transport processes: from the buffer hopper 2 to the blending silo 4, through internal circulation in the blending silo 4 for blending and purification / degassing, and from the blending silo 4 to the washing machine 6. This ensures the performance of the PPC granules during transport and improves transport efficiency.
[0033] The PPC granule conveying device in this embodiment uses low-temperature cold air to convey PPC granules, which can avoid the problem of material sticking caused by friction heating during conveying. Furthermore, the coordinated control of the conveying air volume and the amount of PPC material can avoid particle damage caused by excessive collision of PPC granules during conveying. This can avoid the adverse effects of material sticking and collision damage on the performance of PPC granules, ensuring the material performance of PPC granules in low-temperature pneumatic conveying. Moreover, the use of low-temperature pneumatic conveying at multiple conveying and transfer nodes can improve the overall device's ability to ensure the performance of PPC granules and also improve the feeding efficiency of PPC granules.
[0034] In this specific implementation, elbow structures 30 are provided at the corners of the mixing and feeding pipeline 3, the internal circulation pipeline 5, and the washing and feeding pipeline 6. The elbow structure 30 can reduce the friction coefficient between PPC particles and the pipeline, reduce local frictional heating and particle accumulation, and further reduce the risk of adhesion.
[0035] Specifically, the elbow structure 30 includes straight pipe sections at both ends and a transition section connecting the two straight pipe sections. The straight pipe sections at both ends are perpendicular to each other to achieve a smooth connection at the corner of the pipeline. The outer wall of the transition section is provided with an inclined plate 301, where the outer wall refers to the outward side of the corner. The inclined plate 301 enables tangential conveying of PPC granules when passing through the corner elbow, reducing friction between the material and the pipeline and reducing the generation of stringy material. More specifically, the two ends of the inclined plate 301 are connected to the outer wall of the straight pipe section. The inclination angle of the inclined plate 301 is 40° to 50°, preferably 45°, so as to achieve 90° tangential conveying of the material when passing through the elbow, further improving the effect of reducing friction between the material and the pipeline and reducing the generation of stringy material.
[0036] The mixing and feeding pipeline 3 is equipped with a mixing feed shoe 31. The first interface of the mixing feed shoe 31 is connected to the discharge pipeline of the buffer hopper 2, the second interface of the mixing feed shoe 31 is connected to the low-temperature cold air, and the third interface of the mixing feed shoe 31 is connected to the mixing and feeding pipeline 3. By using the mixing feed shoe 31, the discharge pipeline of the buffer hopper 2, the conveyed low-temperature cold air, and the mixing and feeding pipeline 3 can be connected.
[0037] Similarly, the internal circulation pipeline 5 is equipped with an internal circulation feeding shoe 51. The first interface of the internal circulation feeding shoe 51 is connected to the discharge pipeline of the mixing silo 4, the second interface of the internal circulation feeding shoe 51 is connected to the low-temperature cold air, and the third interface of the internal circulation feeding shoe 51 is connected to the internal circulation pipeline 5. The washing and feeding pipeline 6 is equipped with a washing feeding shoe 61. The first interface of the washing feeding shoe 61 is connected to the discharge pipeline of the mixing silo 4, the second interface of the washing feeding shoe 61 is connected to the low-temperature cold air, and the third interface of the washing feeding shoe 61 is connected to the washing and feeding pipeline 6.
[0038] The blending feed line 3 and the washing feed line 6 are equipped with reversing valves 20 to switch the direction of PPC granular material conveying. The discharge lines of the blending silo 4 include a first branch discharge line and a second branch discharge line. The first branch discharge line is connected to the internal circulation line 5, and the second branch discharge line is connected to the washing feed line 6. Both the first and second branch discharge lines are equipped with reversing valves 20. By designing two branch discharge lines, independent conveying with the internal circulation line 5 and the washing feed line 6 can be achieved, improving the precise control of PPC granular material conveying. Specifically, the discharge lines of the blending silo 4 have a main discharge line connected to its discharge port, which is connected to both the first and second branch discharge lines. A second gate valve 41 and a second rotary valve 42 are installed on the main discharge line. An internal circulation valve 52 is installed on the first branch discharge line, and a washing valve 62 is installed on the second branch discharge line.
[0039] The heat exchanger 10 is connected to a low-temperature water inlet pipe 11 and a low-temperature water outlet pipe 12. The water temperature in the low-temperature water outlet pipe 12 does not exceed 10°C. That is, the low-temperature water in the heat exchanger 10 is used to cool the air in the compressor 9 to about 10°C to achieve a suitable temperature for conveying PPC granules. For example, the low-temperature water in the low-temperature water inlet pipe 11 can be controlled at about 5°C, and the low-temperature water in the low-temperature water outlet pipe 12 can be controlled at about 10°C to keep the low-temperature cold air at about 10°C.
[0040] On the other hand, this embodiment also provides a method for conveying polypropylene carbonate granules, including the above-mentioned polypropylene carbonate granule conveying device, wherein the conveying steps of the polypropylene carbonate granules include:
[0041] The first gate valve 21 and the first rotary valve 22 of the discharge pipeline of the buffer hopper 2 are adjusted synchronously to control the discharge load of polypropylene carbonate granules in the buffer hopper 2.
[0042] The low-temperature cold air generated by the low-temperature air supply unit is used to transport the polypropylene carbonate granules discharged from the buffer hopper 2 to the blending silo 4 through the blending and feeding pipeline 3.
[0043] The second gate valve 41 and the second rotary valve 42 of the discharge pipeline of the blending silo 4 are adjusted synchronously to control the discharge load of polypropylene carbonate granules in the blending silo 4. The polypropylene carbonate granules discharged from the blending silo 4 are re-entered into the blending silo 4 through the internal circulation pipeline 5 using low temperature cold air to perform self-blending and purification degassing of the polypropylene carbonate granules.
[0044] The second gate valve 41 and the second rotary valve 42 of the discharge pipeline of the blending silo 4 are adjusted synchronously to control the discharge load of polypropylene carbonate granules in the blending silo 4. The polypropylene carbonate granules discharged from the blending silo 4 are sent into the washing machine 7 through the washing and feeding pipeline 6 using low-temperature cold air. The polypropylene carbonate granules are then cleaned and dust removed in the washing machine 7. After being cleaned and dust removed, the polypropylene carbonate granules are discharged from the washing machine 7 and enter the packaging silo 8.
[0045] Specifically, the PPC granules in the buffer hopper 2 originate from the vibrating screen 1. After being extruded and pelletized by a twin-screw extruder, the PPC granules are first fed into the vibrating screen 1 for screening. Under the action of the vibrating screen 1, the qualified PPC granules pass smoothly through the screen and fall into the buffer hopper 2. A third rotary valve 71 is designed in the connecting pipeline between the washing machine 7 and the packaging hopper 8 to ensure that the PPC granules are stably transported from the washing machine 7 to the packaging hopper 8, where they await subsequent packaging and storage.
[0046] The polypropylene carbonate (PPC) granule conveying device and method of this embodiment can solve the problem of PPC granule adhesion during conveying. Through the coordinated control of low-temperature medium and gradient airflow, the temperature of the conveying medium can be precisely controlled at ≤20℃, and the flow rate can be matched with 1000-3000 Nm depending on the conveying distance (10-100m). 3 With a gradient airflow rate of / h, the maximum temperature of polypropylene carbonate granules inside the pipeline during pneumatic conveying is ≤30℃, far below its softening temperature. After pneumatic conveying, the granule adhesion rate is ≤1.5%, and the pipeline blockage rate is reduced to below 0.1%, a significant improvement over traditional ambient temperature pneumatic conveying processes (adhesion rate 15-20%). Furthermore, it ensures stable performance of the conveyed PPC granules; there is no significant temperature rise during low-temperature pneumatic conveying, and the retention rate of mechanical properties (tensile strength, elongation at break) is ≥98%, avoiding material deterioration caused by frictional heating in traditional pneumatic conveying. The product qualification rate is increased to over 99.5%. In addition, it boasts high conveying efficiency and wide adaptability, enabling continuous conveying over long distances of 10-100m. A single unit can convey 5-50t per hour, adapting to polypropylene carbonate granules of different particle sizes to meet the conveying needs of large-scale production. Furthermore, the elbow structure reduces the friction coefficient between particles and the pipe. Arc-shaped buffer structures are set at pipe elbows, inlets, and outlets to reduce local frictional heat generation and particle accumulation, further reducing the risk of adhesion.
[0047] Where the embodiments do not contradict each other, at least some of the technical solutions in each embodiment can be recombine to form the essential technical solution of the present invention. Of course, the embodiments can also reference or include each other. Furthermore, it should be noted that adaptive adjustments and modifications made by those skilled in the art when recombinating the technical means described in the embodiments will also fall within the protection scope of the present invention.
[0048] The technical principles of the present invention have been described above in conjunction with specific embodiments. However, it should be noted that these descriptions are merely for explaining the principles of the present invention and should not be construed as limiting the scope of protection of the present invention in any way. Based on this explanation, those skilled in the art can conceive of other specific embodiments or equivalent substitutions of the present invention without creative effort, and all such embodiments will fall within the scope of protection of the present invention.
Claims
1. A polypropylene carbonate granule conveying device, characterized in that, include: The buffer hopper (2) has a discharge pipeline equipped with a first slide gate valve (21), a first rotary valve (22) and a first valve (23); The mixing silo (4) has a first inlet connected to the discharge pipeline of the buffer hopper (2) via a mixing feed pipeline (3), and a second inlet connected to an internal circulation pipeline (5) connected to the discharge pipeline of the mixing silo (4). The discharge pipeline of the mixing silo (4) is equipped with a second gate valve (41) and a second rotary valve (42). Washer (7), the inlet of which is connected to a washing feed line (6), which is connected to the discharge line of the mixing silo (4); Packaging hopper (8), the inlet of which is connected to the outlet of the washing machine (7) via a pipeline; The low-temperature air supply unit includes a compressor (9) and a heat exchanger (10) connected to the compressor (9). The air supplied by the compressor (9) is heated by the heat exchanger (10) to form low-temperature cold air. The low-temperature cold air is connected to the mixing feed line (3), the internal circulation line (5) and the washing feed line (6).
2. The polypropylene carbonate granule conveying device according to claim 1, characterized in that: The corners of the mixing and feeding pipeline (3), the internal circulation pipeline (5) and the washing and feeding pipeline (6) are provided with elbow structures (30).
3. The polypropylene carbonate granule conveying device according to claim 2, characterized in that: The elbow structure (30) includes straight pipe sections at both ends and a transition section connecting the straight pipe sections at both ends. The straight pipe sections at both ends are perpendicular to each other, and the outer wall of the transition section is provided with an inclined plate (301).
4. The polypropylene carbonate granule conveying device according to claim 3, characterized in that: The two ends of the inclined plate (301) are connected to the outer wall of the straight pipe section, and the inclination angle of the inclined plate (301) is 40° to 50°.
5. The polypropylene carbonate granule conveying device according to claim 1, characterized in that: The mixing and feeding pipeline (3) is equipped with a mixing and feeding shoe (31). The first interface of the mixing and feeding shoe (31) is connected to the discharge pipeline of the buffer hopper (2), the second interface of the mixing and feeding shoe (31) is connected to the low temperature cold air, and the third interface of the mixing and feeding shoe (31) is connected to the mixing and feeding pipeline (3).
6. The polypropylene carbonate granule conveying device according to claim 1, characterized in that: The internal circulation pipeline (5) is equipped with an internal circulation feeding shoe (51). The first interface of the internal circulation feeding shoe (51) is connected to the discharge pipeline of the mixing silo (4). The second interface of the internal circulation feeding shoe (51) is connected to the low temperature cold air. The third interface of the internal circulation feeding shoe (51) is connected to the internal circulation pipeline (5).
7. The polypropylene carbonate granule conveying device according to claim 1, characterized in that: The washing and feeding pipeline (6) is equipped with a washing and feeding shoe (61). The first interface of the washing and feeding shoe (61) is connected to the discharge pipeline of the mixing silo (4). The second interface of the washing and feeding shoe (61) is connected to the low temperature cold air. The third interface of the washing and feeding shoe (61) is connected to the washing and feeding pipeline (6).
8. The polypropylene carbonate granule conveying device according to claim 1, characterized in that: The mixing and feeding pipeline (3) and the washing and feeding pipeline (6) are equipped with reversing valves (20). The discharge pipeline of the mixing silo (4) includes a first branch discharge pipeline and a second branch discharge pipeline. The first branch discharge pipeline is connected to the internal circulation pipeline (5), and the second branch discharge pipeline is connected to the washing and feeding pipeline (6). The first branch discharge pipeline and the second branch discharge pipeline are equipped with reversing valves (20).
9. A polypropylene carbonate granule conveying device according to claim 1, characterized in that: The heat exchanger (10) is connected to a low-temperature water inlet pipe (11) and a low-temperature water outlet pipe (12), and the water temperature in the low-temperature water outlet pipe (11) is not higher than 10°C.
10. A method for conveying polypropylene carbonate granules, characterized in that: The polypropylene carbonate granule conveying device according to any one of claims 1-9, wherein the conveying step of the polypropylene carbonate granules includes: The first gate valve (21) and the first rotary valve (22) of the discharge pipeline of the buffer hopper (2) are adjusted synchronously to control the discharge load of the polypropylene carbonate granules in the buffer hopper (2); The low-temperature cold air generated by the low-temperature air supply unit is used to transport the polypropylene carbonate granules discharged from the buffer hopper (2) to the blending silo (4) through the blending and feeding pipeline (3); The second gate valve (41) and the second rotary valve (42) of the discharge pipeline of the blending silo (4) are adjusted synchronously to control the discharge load of the polypropylene carbonate granules in the blending silo (4). The polypropylene carbonate granules discharged from the blending silo (4) are re-entered into the blending silo (4) through the internal circulation pipeline (5) by the low temperature cold air to perform self-blending and purification degassing of the polypropylene carbonate granules. The second gate valve (41) and the second rotary valve (42) of the discharge pipeline of the blending silo (4) are adjusted synchronously to control the discharge load of the polypropylene carbonate granules in the blending silo (4). The polypropylene carbonate granules discharged from the blending silo (4) are sent to the washing and feeding pipeline (6) through the low-temperature cold air to the washing machine (7). The polypropylene carbonate granules are then cleaned and dust removed in the washing machine (7). After being cleaned and dust removed, the polypropylene carbonate granules are discharged from the washing machine (7) and enter the packaging silo (8).