Polymer solution separation system

Abstract

The invention provides a polymer solution separation system which comprises a flash tank, a settling tank, a first separation tower, an MG refining tower, a methanol separation tower and a second separation tower, the flash tank, the settling tank and the first separation tower are sequentially connected, the MG refining tower and the methanol separation tower are communicated with the first separation tower, so that MG extracted from a side line of the first separation tower enters the MG refining tower, and the MG extracted from a side line of the methanol separation tower enters the second separation tower. A part of components discharged from the top of the first separation tower enter the methanol separation tower, and the second separation tower is connected with the methanol separation tower, so that a part of components discharged from the top of the second separation tower enter the second separation tower. MG extracted from the side line of the first separation tower can accurately enter the MG refining tower for purification, light components discharged from the top can be guided into the methanol separation tower for further treatment, and deep separation is performed through the second separation tower, so that directional shunting and efficient separation of multiple components in a polymer solution are realized, and the recovery pertinence of each component and the operation smoothness of the system are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of coal chemical industry, and particularly relates to a polymer solution separation system. BACKGROUND

[0002] Polyglycolic acid (PGA) is a coal-based biodegradable material produced from coal resources. Due to its high biocompatibility, high mechanical properties and high barrier properties, PGA has wide application potential in food packaging, biomedical, agricultural construction and other fields.

[0003] However, the production cost of PGA is currently high, and it lacks market competitiveness compared with traditional plastics. In the production process of PGA, the polymer mixed solution, as an intermediate product, contains oligomers, methyl glycolate (MG), methanol, formic acid and other components. The existing technology fails to achieve the expected separation effect when separating and recycling these components. In particular, the presence of solid oligomers seriously affects the stability of equipment operation. Solid oligomers can block filters, pipelines and other key equipment, resulting in reduced production efficiency and increased maintenance costs. In addition, due to the poor separation of components, the material recycling rate is low, which further limits the production efficiency and economic benefits. Therefore, it is of great significance to optimize and improve the existing separation and recovery technology to improve the recovery rate and purity of each component for the improvement of PGA production process. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is to provide a polymer solution separation system which can improve the separation and recovery effect of intermediate products.

[0005] In order to solve the above problems, the present application provides a polymer solution separation system, which comprises a flash tank, a settling tank, a first separation tower, an MG refining tower, a methanol separation tower and a second separation tower. The flash tank, the settling tank and the first separation tower are connected in sequence. The MG refining tower and the methanol separation tower are respectively connected with the first separation tower, so that the MG collected from the side line of the first separation tower enters the MG refining tower, and part of the components discharged from the top of the first separation tower enters the methanol separation tower. The second separation tower is connected with the methanol separation tower, so that part of the components discharged from the top of the second separation tower enters the second separation tower.

[0006] Optionally, a wiped film evaporator and a heavy liquid tank are sequentially arranged in the flow path between the settling tank and the first separation column, the discharge end of the settling tank is in communication with the entering end of the wiped film evaporator, so that the mixed liquid overflowing from the settling tank enters the wiped film evaporator through a delivery pump and a basket filter, the entering end of the heavy liquid tank is in communication with the lower discharge end of the wiped film evaporator, and the lower discharge end of the heavy liquid tank is in communication with the settling tank. The upper discharge end of the wiped film evaporator and the upper discharge end of the heavy liquid tank are both in communication with a wiped film evaporation condenser, the first discharge end of the wiped film evaporation condenser is in communication with the first separation column, and a wiped film vacuum pump is arranged in the flow path therebetween; the second discharge end of the wiped film evaporation condenser is in communication with the first separation column, and a wiped film clear liquid tank and a wiped film clear liquid pump are sequentially arranged in the flow path therebetween.

[0007] Optionally, the upper discharge end of the first separation column is in communication with a first column condenser, so that the light components in the first separation column enter the first column condenser, the condensed gas discharge end of the first column condenser is sequentially in communication with a first column reflux tank and a first column reflux pump, the discharge end of the first column reflux pump is respectively in communication with the first separation column and the methanol separation column; the non-condensed gas discharge end of the first column condenser is in communication with a waste gas system, and a first column vacuum pump is arranged in the flow path therebetween. The first side line discharge end of the first separation column is in communication with the MG refining column, and a first column side line discharge pump is arranged in the flow path between the first side line discharge end and the MG refining column.

[0008] Optionally, a first column circulating loop is arranged at the lower part of the first separation column, and a first column reboiler and a first column kettle forced circulation pump are arranged in the first column circulating loop. The bottom discharge end of the first separation column is in communication with a depolymerization system, and a first column kettle discharge pump and a first column kettle discharge heater are arranged in the flow path therebetween.

[0009] Optionally, the upper discharge end of the MG refining column is in communication with a refining column condenser, so that the light components in the MG refining column enter the refining column condenser, the condensed gas discharge end of the refining column condenser is sequentially in communication with a refining column reflux tank and a refining column reflux pump, the discharge end of the refining column reflux pump is respectively in communication with the MG refining column and the methanol separation column; the non-condensed gas discharge end of the refining column condenser is in communication with a waste gas system, and a refining column vacuum pump is arranged in the flow path therebetween.

[0010] Optionally, one lateral discharge end of the MG refining column is in communication with a heavy polyol tank, and a refining column reboiler is arranged in the flow path therebetween; the bottom discharge end of the MG refining column is in communication with the heavy polyol tank, and a refining column kettle pump is arranged in the flow path therebetween.

[0011] Optionally, the upper discharge end of the methanol separation tower is communicated with a methanol separation condenser, so that the light components in the methanol separation tower enter the methanol separation condenser, the condensed gas discharge end of the methanol separation condenser is sequentially communicated with a methanol separation reflux tank and a methanol separation reflux pump, the discharge end of the methanol separation reflux pump is respectively communicated with the methanol separation tower and the second separation tower; the non-condensed gas discharge end of the methanol separation condenser is communicated with a waste gas system.

[0012] Optionally, the lower part of the methanol separation tower is provided with a methanol separation circulating loop, and a methanol separation reboiler is arranged on the methanol separation circulating loop. The bottom discharge end of the methanol separation tower is communicated to a mixed alcohol tank, and a methanol separation tower kettle pump and a methanol separation tower kettle cooler are arranged on the flow path therebetween.

[0013] Optionally, the upper discharge end of the second separation tower is communicated with a separation two-tower condenser, so that the light components in the second separation tower enter the separation two-tower condenser, the condensed gas discharge end of the separation two-tower condenser is sequentially communicated with a separation two-tower reflux tank and a separation two-tower reflux pump, the discharge end of the separation two-tower reflux pump is respectively communicated with the second separation tower and the mixed alcohol tank; the non-condensed gas discharge end of the separation two-tower condenser is communicated with a waste gas system, and a separation two-tower vacuum pump is arranged on the flow path therebetween.

[0014] Optionally, the lower part of the second separation tower is provided with a separation two-tower circulating loop, and a separation two-tower reboiler is arranged on the separation two-tower circulating loop. The bottom discharge end of the second separation tower is communicated to a methanol buffer tank and a ring unit buffer tank, and a separation two-tower kettle discharge pump and a separation two-tower kettle cooler are arranged on the flow path therebetween.

[0015] The polymer solution separation system provided in the embodiment of the present application, by sequentially constructing a flash tank, a settling tank, a first separation tower, an MG refining tower, a methanol separation tower and a second separation tower into a complete separation system, clearly defining the communication relationship of each core equipment, so that the MG collected from the side line of the first separation tower can be accurately introduced into the MG refining tower for purification, the light components discharged from the top can be introduced into the methanol separation tower for further treatment, and finally the deep separation through the second separation tower, realizing the directional diversion and efficient separation of multiple components in the polymer solution, greatly improving the recovery specificity of each component and the smoothness of system operation. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The system principle diagram of the polymer solution separation system of the embodiment of the present application.

[0017] The reference signs are represented as: 1. Flash tank; 2. Settling tank; 3. Transfer pump; 4. Basket filter; 5. Scraped film evaporator; 6. Heavy liquid tank; 7. Heavy liquid transfer pump; 8. Scraped film evaporator condenser; 9. Scraped film vacuum pump; 10. Scraped film clear liquid tank; 11. Scraped film clear liquid pump; 12. First separation tower; 13. Separation tower condenser; 14. Separation tower vacuum pump; 15. Separation tower reflux tank; 16. Separation tower reflux pump; 17. Separation tower bottom discharge pump; 18. Separation tower bottom discharge heater; 19. Separation tower side discharge pump; 20. MG refining tower; 21. MG refining tower side discharge pump; 22. Refining tower bottom pump; 23. Refining tower condenser; 2 4. Refining tower vacuum pump; 25. Refining tower reflux tank; 26. Refining tower reflux pump; 27. Methanol separation tower; 28. Methanol separation tower bottom pump; 29. ​​Methanol separation tower bottom cooler; 30. Methanol separation condenser; 31. Methanol separation reflux tank; 32. Methanol separation reflux pump; 33. Second separation tower; 34. Second separation tower bottom discharge pump; 35. Second separation tower bottom cooler; 36. Second separation tower condenser; 37. Second separation tower reflux tank; 38. Second separation tower reflux pump; 39. First separation tower reboiler; 40. First separation tower bottom forced circulation pump; 41. Refining tower reboiler; 42. Methanol separation reboiler; 43. Second separation tower reboiler. Detailed Implementation

[0018] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0020] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0021] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0022] See also Figure 1 As shown in the embodiments of this application, a polymer solution separation system is provided, including a flash tank 1, a settling tank 2, a first separation tower 12, an MG purification tower 20, a methanol separation tower 27, and a second separation tower 33. The flash tank 1, the settling tank 2, and the first separation tower 12 are connected in sequence. The MG purification tower 20 and the methanol separation tower 27 are respectively connected to the first separation tower 12, so that the MG sampled from the side stream of the first separation tower 12 enters the MG purification tower 20, and a portion of the components discharged from the top of the first separation tower 12 enters the methanol separation tower 27. The second separation tower 33 is connected to the methanol separation tower 27, so that a portion of the components discharged from the top of the second separation tower 33 enters the second separation tower 33.

[0023] By sequentially constructing a complete separation system from flash tank 1, settling tank 2, first separation tower 12, MG refining tower 20, methanol separation tower 27, and second separation tower 33, and clarifying the connection relationship of each core device, the MG collected from the side stream of the first separation tower 12 can be accurately introduced into the MG refining tower 20 for purification, and the light components discharged from the top can be introduced into the methanol separation tower 27 for further processing. Finally, they are deeply separated by the second separation tower 33, realizing the directional diversion and efficient separation of multiple components in the polymer solution, which greatly improves the specificity of the recovery of each component and the smoothness of system operation.

[0024] The flash tank 1, settling tank 2, and first separation tower 12 are connected sequentially along the process direction of polymer solution treatment. In terms of the overall process flow, the polymer solution to be separated first enters the flash tank 1 for preliminary treatment. After the preliminary treatment, the solution is transferred to the settling tank 2. After being treated in the settling tank 2, the solution is then transported to the first separation tower 12, forming a pretreatment link that provides a foundation for the precise separation of subsequent components.

[0025] The MG refining tower 20 is connected to the first separation tower 12 via a pipeline. During the distillation process of the first separation tower 12, MG is discharged from the side stream of the tower as an intermediate component. The MG refining tower 20, which is connected to the first separation tower 12, can receive the MG collected from the side stream, thereby further purifying the MG and achieving separate refining of the MG component.

[0026] The methanol separation tower 27 is connected to the first separation tower 12 via a pipeline. During the distillation process in the first separation tower 12, light components such as methanol and formic acid move upward and are discharged from the top of the tower. The methanol separation tower 27, which is connected to the top of the first separation tower 12, can receive the light components discharged from the top of the tower and then perform targeted separation on the light components to avoid mixing with other components and affecting the separation effect, thus creating conditions for the separation of methanol and formic acid.

[0027] The second separation tower 33 is connected to the methanol separation tower 27 via a pipeline. When processing the light components received from the first separation tower 12, the methanol separation tower 27 will perform preliminary separation of methanol and formic acid. Then, the part of the methanol component mainly containing a small amount of impurities discharged from the top of the methanol separation tower 27 will be transported to the second separation tower 33. Through the deep distillation of the second separation tower 33, the impurities will be further removed, and finally high-purity methanol will be obtained, thus completing the separation of the light components.

[0028] A scraped film evaporator 5 and a heavy liquid tank 6 are sequentially arranged in the flow path between the settling tank 2 and the first separation tower 12. The discharge end of the settling tank 2 is connected to the inlet end of the scraped film evaporator 5 so that the mixed liquid overflowing from the settling tank 2 enters the scraped film evaporator 5 after passing through the transfer pump 3 and the basket filter 4. The inlet end of the heavy liquid tank 6 is connected to the lower discharge end of the scraped film evaporator 5, and the lower discharge end of the heavy liquid tank 6 is connected to the settling tank 2.

[0029] The upper discharge end of the scraped film evaporator 5 and the upper discharge end of the heavy liquid tank 6 are both connected to the scraped film evaporator condenser 8; the first discharge end of the scraped film evaporator condenser 8 is connected to the first separation tower 12, and a scraped film vacuum pump 9 is provided in the flow path between them; the second discharge end of the scraped film evaporator condenser 8 is connected to the first separation tower 12, and a scraped film clear liquid tank 10 and a scraped film clear liquid pump 11 are arranged sequentially in the flow path between them.

[0030] By setting up a scraped film evaporator 5 and a heavy liquid tank 6 between the settling tank 2 and the first separation tower 12, and pre-treating the overflow liquid from the settling tank 2 with a transfer pump 3 and a basket filter 4, and then enhancing solid-liquid separation through the scraped film evaporator 5, the solid components can be recycled back to the settling tank 2 at the lower discharge end of the heavy liquid tank 6. The scraped film evaporator condenser 8, together with a vacuum pump, a scraped film clear liquid tank 10 and a clear liquid pump, can efficiently introduce the gas phase and liquid phase components into the first separation tower 12, effectively reducing the interference of solid impurities on the subsequent distillation process, and improving the material pretreatment effect and the stability of the separation system.

[0031] The system incorporates a settling tank 2 and a scraped-film evaporator 5 to separate solid polymers with different particle sizes, effectively reducing the moisture content of the solid phase. The liquid solvent is processed through a series of distillation steps, including a separation tower, an MG purification tower 20, a methanol separation tower 27, and a separation tower 2, to achieve efficient purification of solvents such as MG, heavy polyols, methanol, and formic acid, ensuring that each solvent reaches higher purity standards. This not only improves material recovery rates but also significantly reduces the production cost of coal-based biodegradable materials. The combination of physical separation and distillation technologies solves the problem of incomplete material separation in existing processes, improving resource utilization efficiency and reducing energy consumption and production costs. Specifically, the optimized separation and distillation steps enhance equipment stability, reduce the impact of solid particles on the equipment, avoid clogging, and improve production efficiency and equipment lifespan. Furthermore, by improving the recovery rate and purity of each component, production costs are further reduced, providing solid technical support for the large-scale industrial production of coal-based biodegradable materials.

[0032] In the material flow path between the settling tank 2 and the first separation tower 12, a scraped film evaporator 5 and a heavy liquid tank 6 are sequentially installed. This allows for secondary deep pretreatment of the overflow liquid after the settling tank 2 is treated. The scraped film evaporator 5 enhances the solid-liquid separation effect, while the heavy liquid tank 6 is used to temporarily store the heavy components discharged from the scraped film evaporator 5, forming a pretreatment link and reducing the entry of solid impurities into the first separation tower 12.

[0033] The discharge end of the settling tank 2 is connected to the inlet end of the scraped film evaporator 5 through a pipe. The mixed liquid overflowing from the settling tank 2 will first be pressurized by the transfer pump 3, and then filtered by the basket filter 4 to remove some particulate impurities before entering the scraped film evaporator 5 for evaporation and separation. This can prevent large particulate impurities from clogging the scraped film evaporator 5 and ensure its stable operation.

[0034] The inlet of the heavy liquid tank 6 is connected to the lower outlet of the scraped film evaporator 5 via a pipe. It is used to receive the heavy components containing solid particles that have not been evaporated in the scraped film evaporator 5. The lower outlet of the heavy liquid tank 6 is connected to the settling tank 2 via a pipe, so that the temporarily stored heavy components can be returned to the settling tank 2 for separation again, thereby realizing the recycling of solid components and improving the material utilization rate.

[0035] The lower discharge end of the heavy liquid tank 6 is connected to the settling tank 2 via a pipeline, and a heavy liquid transfer pump 7 is installed on the pipeline.

[0036] In addition to being connected to the scraped film evaporator 5, the discharge end of the basket filter 4 is also connected to the middle inlet of the first separation tower 12 and the top inlet of the heavy liquid tank 6. The separated liquid solvent enters the first separation tower 12 for preliminary distillation.

[0037] Both the upper discharge end of the scraped film evaporator 5 and the upper discharge end of the heavy liquid tank 6 discharge gaseous components. Both the upper discharge ends of the scraped film evaporator 5 and the upper discharge end of the heavy liquid tank 6 are connected to the scraped film evaporator condenser 8 via pipelines. After the gaseous components condense in the condenser, the first discharge end of the scraped film evaporator condenser 8 is connected to the first separation tower 12 via a pipeline equipped with a vacuum pump, allowing incompletely condensed gaseous components to be pumped to the first separation tower 12. The second discharge end of the scraped film evaporator condenser 8 is connected to the first separation tower 12 via a pipeline sequentially equipped with a scraped film clear liquid tank 10 and a scraped film clear liquid pump 11. The condensed liquid components are first temporarily stored in the scraped film clear liquid tank 10, and then pressurized by the clear liquid pump before being transported to the first separation tower 12, achieving separate and efficient transport of gaseous and liquid components.

[0038] The upper discharge end of the flash tank 1 and the upper discharge end of the settling tank 2 can both be connected to the middle inlet end of the first separation tower 12 through pipelines, and control valves are respectively installed on the pipelines.

[0039] The upper discharge end of the first separation tower 12 is connected to the condenser 13 of the first separation tower, so that the light components in the first separation tower 12 enter the condenser 13 of the first separation tower. The condensate discharge end of the condenser 13 of the first separation tower is connected in sequence to the reflux tank 15 of the first separation tower and the reflux pump 16 of the first separation tower. The discharge end of the reflux pump 16 of the first separation tower is connected to the first separation tower 12 and the methanol separation tower 27 respectively. The non-condensable gas discharge end of the condenser 13 of the first separation tower is connected to the waste gas system, and a vacuum pump 14 of the first separation tower is installed in the flow path between them.

[0040] The first side discharge end of the first separation tower 12 is connected to the MG refining tower 20, and a separation tower side discharge pump 19 is provided in the flow path between the first side discharge end and the MG refining tower 20.

[0041] The upper discharge end of the first separation tower 12 is connected to the condenser 13, reflux tank and reflux pump to form a condensation reflux loop, so that the light components are effectively condensed and rationally distributed to the reflux of the first separation tower 12 and the methanol separation tower 27. The non-condensable gas is introduced into the waste gas system by a vacuum pump to avoid pollution. The side stream of the first separation tower 12 is directly connected to the MG refining tower 20 through the discharge pump to ensure rapid and accurate separation of MG components. This not only optimizes the separation efficiency of the first separation tower 12, but also provides a foundation for subsequent MG refining and deep treatment of light components.

[0042] The upper discharge end of the first separation tower 12 is connected to the condenser 13 of the first separation tower via a pipeline. During the distillation process, light components such as methanol and formic acid in the first separation tower 12 will move upward and enter the condenser 13 of the first separation tower from the upper discharge end. After the light components are condensed into liquid phase in the condenser, the condensate discharge end of the condenser 13 of the first separation tower is connected to the reflux tank 15 of the first separation tower and the reflux pump 16 of the first separation tower via pipelines. The discharge end of the reflux pump 16 of the first separation tower is divided into two paths and connected to the first separation tower 12 and the methanol separation tower 27 respectively via pipelines. Part of the condensate is returned to the first separation tower 12 to maintain the distillation balance in the tower, and the other part is sent to the methanol separation tower 27 for deep separation to achieve reasonable distribution of light components.

[0043] The non-condensable gas discharge end of the condenser 13 of the separation tower is connected to the waste gas system through a pipeline, and a vacuum pump 14 of the separation tower is installed on the pipeline. When running, the vacuum pump can pump the non-condensable gas in the condenser to the waste gas system for centralized treatment, so as to avoid the accumulation of non-condensable gas in the system and affect the separation effect, while reducing environmental pollution.

[0044] The first side stream discharge end of the first separation tower 12 is connected to the MG refining tower 20 through a pipeline, and a side stream discharge pump 19 and an activated carbon adsorption device are installed on the pipeline. Since MG is concentrated in the side stream position as an intermediate component in the first separation tower 12, most of the MG can be transported to the MG refining tower 20 for further distillation by the side stream discharge pump 19, ensuring that the MG component can quickly leave the first separation tower 12 and enter the subsequent refining process, thereby improving the separation efficiency.

[0045] The lower part of the first separation tower 12 is provided with a separation tower circulation loop, and the separation tower reboiler 39 and the separation tower bottom forced circulation pump 40 are provided on the separation tower circulation loop.

[0046] The bottom discharge end of the first separation tower 12 is connected to the depolymerization system, and the flow path between them is provided with a separation tower bottom discharge pump 17 and a separation tower bottom discharge heater 18.

[0047] By setting a circulation loop at the bottom of the first separation tower 12, and installing a reboiler 39 and a forced circulation pump in the reboiler of the first separation tower on the circulation loop, the heating uniformity and separation effect of the material in the tower can be enhanced. The bottom discharge end is directly connected to the depolymerization system through the reboiler discharge pump and heater, so that the heavy components in the reboiler can be quickly returned to the production process for recycling, reducing material waste, improving resource utilization, and ensuring the continuous and stable operation of the first separation tower 12.

[0048] The first separation tower 12 is equipped with a circulation loop at its lower part, which includes a reboiler 39 and a forced circulation pump 40. During operation, the forced circulation pump 40 transports the liquid from the bottom of the first separation tower 12 to the reboiler 39. After being heated and partially vaporized in the reboiler, the liquid returns to the first separation tower 12. This circulation enhances the heat and mass transfer of the material within the tower, ensuring more thorough distillation and separation.

[0049] The bottom discharge end of the first separation tower 12 is connected to the depolymerization system through a pipeline. A separation tower bottom discharge pump 17 and a separation tower bottom discharge heater 18 are installed sequentially on the pipeline. The heavy components containing incompletely separated polymer components in the tower bottom are transported to the separation tower bottom discharge heater 18 by the action of the separation tower bottom discharge pump 17. After being heated, they are sent back to the depolymerization system to participate in the reaction again, realizing the recycling of heavy components and reducing material waste.

[0050] The upper discharge end of the MG refining tower 20 is connected to the refining tower condenser 23 so that the light components in the MG refining tower 20 enter the refining tower condenser 23. The condensate discharge end of the refining tower condenser 23 is connected in sequence to the refining tower reflux tank 25 and the refining tower reflux pump 26. The discharge end of the refining tower reflux pump 26 is connected to the MG refining tower 20 and the methanol separation tower 27 respectively. The non-condensable gas discharge end of the refining tower condenser 23 is connected to the waste gas system, and a refining tower vacuum pump 24 is installed in the flow path between them.

[0051] By setting a condenser 23, a reflux tank, and a reflux pump at the top of the MG refining tower 20 to form a high-efficiency condensation and reflux system, the light components can be condensed and refluxed back to the MG refining tower 20 or introduced into the methanol separation tower 27 for further purification. The non-condensable gas is introduced into the waste gas system through a vacuum pump, which avoids the impact of impurity accumulation on the purity of MG, significantly improves the accuracy of the MG refining process and the purity of the product, and ensures the stability and efficiency of the refining process.

[0052] The upper discharge end of the MG refining tower 20 is connected to the refining tower condenser 23 via a pipeline. During the MG refining process, light components such as a small amount of methanol and formic acid move upward and enter the refining tower condenser 23 from the upper discharge end. After the light components condense into liquid phase, the condensate discharge end of the refining tower condenser 23 is connected to the refining tower reflux tank 25 and the refining tower reflux pump 26 in sequence via pipelines. The discharge end of the refining tower reflux pump 26 is divided into two paths and connected to the MG refining tower 20 and the methanol separation tower 27 respectively via pipelines. Part of the condensate is returned to the MG refining tower 20 to maintain the distillation conditions in the tower, and the other part is sent to the methanol separation tower 27 for further separation to avoid the light components affecting the purity of MG.

[0053] The non-condensable gas discharge end of the refining tower condenser 23 is connected to the waste gas system via a pipeline, and a refining tower vacuum pump 24 is installed on this pipeline. During operation, the refining tower vacuum pump 24 can pump the non-condensable gas in the condenser to the waste gas system for treatment, preventing the non-condensable gas from accumulating in the MG refining tower 20, and ensuring the stability of the MG refining process and the purity of the MG product.

[0054] One side discharge end of the MG refining column 20 is connected to the heavy polyol tank, and a reboiler 41 is installed in the flow path between them. The bottom discharge end of the MG refining column 20 is connected to the heavy polyol tank, and a refining column bottom pump 22 is installed in the flow path between them.

[0055] The side discharge end of the MG refining tower 20 is connected to the heavy polyol tank through the reboiler 41 of the refining tower, and the bottom discharge end is also connected to the heavy polyol tank through the reboiler pump 22 of the refining tower. The heavy components in the tower can be efficiently collected to the target storage tank through different paths, realizing the directional recovery of heavy polyols, avoiding the accumulation of heavy components in the tower, optimizing the material flow efficiency of the MG refining tower 20, and improving the recovery rate of heavy polyols.

[0056] The other side discharge end of the MG refining tower 20 is connected to the process system via a pipeline, allowing the MG discharged laterally to return to the process system. An MG refining tower side discharge pump 21 is installed on this pipeline.

[0057] The side discharge end of the MG refining tower 20 is connected to the heavy polyol tank through a pipeline, and a reboiler 41 for the refining tower is installed on the pipeline. The heavy polyol in the MG refining tower 20 will be enriched at the side position. With the heating assistance of the reboiler 41, the heavy polyol can be efficiently transported to the heavy polyol tank for collection, thereby realizing the separation of heavy polyol from MG.

[0058] The bottom discharge end of the MG refining tower 20 is connected to the heavy polyol tank via a pipeline, and a refining tower bottom pump 22 is installed on the pipeline. The heavy polyol remaining in the bottom of the tower is transported to the heavy polyol tank by the action of the refining tower bottom pump 22, and merges with the heavy polyol discharged from the side, ensuring that the heavy components in the MG refining tower 20 are fully recovered and avoiding residues that may affect subsequent operation.

[0059] The upper discharge end of the methanol separation tower 27 is connected to the methanol separation condenser 30 so that the light components in the methanol separation tower 27 enter the methanol separation condenser 30. The condensate discharge end of the methanol separation condenser 30 is connected in sequence to the methanol separation reflux tank 31 and the methanol separation reflux pump 32. The discharge end of the refining tower reflux pump 26 is connected to the methanol separation tower 27 and the second separation tower 33 respectively. The non-condensable gas discharge end of the methanol separation condenser 30 is connected to the waste gas system.

[0060] The upper part of the methanol separator 27 is connected to the methanol separator condenser 30, reflux tank and reflux pump to form a separation loop. After condensation, the light components can be reasonably distributed to the methanol separator 27 for reflux and the second separator 33 for deep separation. The non-condensable gas is introduced into the exhaust gas system to ensure a clean operating environment, enhance the separation effect of methanol and other components, provide high-quality raw materials for the subsequent purification of high-purity methanol in the second separator 33, and improve the fineness of the separation of light components.

[0061] The upper discharge end of the methanol separation tower 27 is connected to the methanol separation condenser 30 via a pipeline. During distillation, the light components, mainly methanol, in the tower will move upward and enter the methanol separation condenser 30. After condensing into a liquid phase, the condensate discharge end of the methanol separation condenser 30 is connected to the methanol separation reflux tank 31 and the methanol separation reflux pump 32 via pipelines. The discharge end of the methanol separation reflux pump 32 is divided into two paths and connected to the methanol separation tower 27 and the second separation tower 33 via pipelines respectively. Part of the condensate is returned to the methanol separation tower 27 to maintain the distillation balance, and the other part is sent to the second separation tower 33 for deep purification to prepare for obtaining high-purity methanol.

[0062] The non-condensable gas discharge end of the methanol separator condenser 30 is connected to the waste gas system through a pipeline. During operation, the non-condensable gas generated in the methanol separator 27 passes through the methanol separator condenser 30 and then directly enters the waste gas system for treatment, thus avoiding interference from the non-condensable gas with the separation and purification of methanol and ensuring the stable operation of the methanol separator 27.

[0063] A methanol separation circulation loop is provided at the bottom of the methanol separation tower 27, and a methanol separation reboiler 42 is provided on the methanol separation circulation loop. The bottom discharge end of the methanol separation tower 27 is connected to the mixed alcohol tank, and a methanol separation tower bottom pump 28 and a methanol separation tower bottom cooler 29 are provided in the flow path between them.

[0064] By setting up a circulation loop containing a methanol separation reboiler 42 at the bottom of the methanol separation tower 27, the gasification separation effect of the material in the tower can be enhanced. The bottom discharge end is connected to the mixed alcohol tank through the tower bottom pump and cooler, so that the heavy components in the tower bottom can be quickly cooled and collected into the mixed alcohol tank. This achieves efficient recovery of heavy components such as formic acid, avoids equipment corrosion or efficiency reduction caused by component residue, and improves the operational stability and resource recovery efficiency of the methanol separation tower 27.

[0065] The methanol separation tower 27 is equipped with a methanol separation circulation loop at its lower part, which includes pipelines and a methanol separation reboiler 42. During operation, the liquid in the bottom of the methanol separation tower 27 can enter the methanol separation reboiler 42, where it is heated, vaporized, and then returned to the tower. This circulating heating method can enhance the separation effect of methanol and heavy components such as formic acid in the tower, ensuring more thorough separation.

[0066] The bottom discharge end of the methanol separation tower 27 is connected to the mixed alcohol tank via a pipeline. A methanol separation tower bottom pump 28 and a methanol separation tower bottom cooler 29 are installed sequentially on the pipeline. The heavy components, mainly formic acid, in the bottom of the tower are transported to the methanol separation tower bottom cooler 29 by the action of the methanol separation tower bottom pump 28. After being cooled down, they are sent to the mixed alcohol tank for temporary storage, so as to achieve efficient collection of heavy components such as formic acid and avoid their accumulation in the bottom of the tower.

[0067] The upper discharge end of the second separation tower 33 is connected to the second separation tower condenser 36 so that the light components in the second separation tower 33 enter the second separation tower condenser 36. The condensate discharge end of the second separation tower condenser 36 is connected in sequence to the second separation tower reflux tank 37 and the second separation tower reflux pump 38. The discharge end of the second separation tower reflux pump 38 is connected to the second separation tower 33 and the mixed alcohol tank respectively. The non-condensable gas discharge end of the second separation tower condenser 36 is connected to the waste gas system, and a second separation tower vacuum pump is installed in the flow path between them.

[0068] The upper part of the second separation tower 33 forms a condensation recovery system through the second separation tower condenser 36, reflux tank and reflux pump. After condensation, the light components can be returned to the second separation tower 33 or introduced into the mixed alcohol tank. The non-condensable gas is introduced into the heat transfer oil furnace as fuel to achieve energy recovery, which reduces waste gas emissions and improves energy utilization. At the same time, the vacuum pump ensures the separation environment inside the tower, which significantly improves the separation accuracy and recovery efficiency of the second separation tower 33 for components such as methanol.

[0069] The upper discharge end of the second separation tower 33 is connected to the condenser 36 of the second separation tower through a pipeline. During the deep distillation process, the light components in the tower will move upward and enter the condenser 36 of the second separation tower. After condensing into liquid phase, the condensate discharge end of the condenser 36 of the second separation tower is connected to the reflux tank 37 and the reflux pump 38 of the second separation tower in sequence through a pipeline. The discharge end of the reflux pump 38 of the second separation tower is divided into two paths and connected to the second separation tower 33 and the mixed alcohol tank respectively through pipelines. Part of the condensate is returned to the second separation tower 33 to maintain the distillation balance in the tower, and the other part is transported to the mixed alcohol tank to achieve the separation and collection of light component impurities.

[0070] The non-condensable gas discharge end of the condenser 36 of the second separation tower is connected to the waste gas system through a pipeline, and a vacuum pump of the second separation tower is installed on the pipeline. When running, the vacuum pump draws the non-condensable gas to the heat transfer oil furnace for combustion, which not only achieves the harmless treatment of non-condensable gas, but also recovers and utilizes its heat energy, thereby improving energy utilization efficiency.

[0071] Non-condensable gas is supplied as fuel to the thermal oil furnace.

[0072] The lower part of the second separation tower 33 is provided with a second separation tower circulation loop, and a second separation tower reboiler 43 is provided on the second separation tower circulation loop. The bottom discharge end of the second separation tower 33 is connected to the methanol buffer tank and the ring forming unit buffer tank, and a second separation tower bottom discharge pump 34 and a second separation tower bottom cooler 35 are provided in the flow path between them.

[0073] By setting up a circulation loop containing a reboiler 43 at the bottom of the second separation tower 33, the separation effect of the materials in the tower can be enhanced. The bottom discharge end is connected to the methanol buffer tank and the ring forming unit buffer tank through the tower bottom discharge pump and cooler, so that high-purity methanol can be directly transported to the subsequent production unit for recycling. This simplifies the material transfer process, improves the recovery rate of methanol and the continuity of the production process, and provides a basis for the recycling of materials after polymer solution separation.

[0074] The second separation tower 33 is equipped with a circulation loop at its lower part. The circulation loop includes pipes and a reboiler 43. During operation, the liquid in the bottom of the second separation tower 33 can enter the reboiler 43. After being heated, the liquid vaporizes and returns to the tower. The circulation heating enhances the separation effect of methanol and impurities in the tower, ensuring that high-purity methanol is finally obtained.

[0075] The bottom discharge end of the second separation tower 33 is connected to the methanol buffer tank and the ring forming unit buffer tank via a pipeline. The pipeline is equipped with a second separation tower bottom discharge pump 34 and a second separation tower bottom cooler 35. The high-purity methanol in the tower bottom is transported to the second separation tower bottom cooler 35 by the action of the second separation tower bottom discharge pump 34. After cooling, it is sent to the methanol buffer tank for temporary storage and the ring forming unit buffer tank for subsequent production, realizing the directional transportation and recycling of high-purity methanol.

[0076] In this embodiment, the separation in settling tank 2 is a physical separation method based on the principle of gravity settling, mainly used to separate suspended solid particles from liquids. Its working principle relies on the density difference between solid particles and liquid. In a static or slowly flowing state, gravity causes the denser solid particles to naturally settle to the bottom of the container, thereby achieving solid-liquid separation.

[0077] The principle of scraped film evaporation is to use a rotating scraper to form a uniform thin liquid film on the heated surface, allowing the material to evaporate rapidly, improving evaporation efficiency and preventing material degradation. As the solvent evaporates, the solution gradually becomes saturated and begins to crystallize. The scraper continuously refreshes the liquid film, promoting uniform crystal growth and ensuring efficient separation and concentration. Finally, the evaporated solvent is condensed and recovered, and the concentrate or crystals are collected from the bottom.

[0078] The principle of a distillation column is to separate components based on their volatility. During operation, heating at the bottom causes partial evaporation of the liquid. The vapor carries the more volatile components upwards, contacting the liquid refluxing from the top of the column on the trays or packing, undergoing multiple vaporization and condensation processes. Each contact further concentrates the low-boiling-point components in the vapor, while the high-boiling-point components remain more concentrated in the liquid phase and flow towards the bottom. Ultimately, a product rich in low-boiling-point components is collected at the top of the column, while a product rich in high-boiling-point components is collected at the bottom. By adjusting parameters such as temperature, pressure, and reflux ratio, the separation effect can be effectively controlled.

[0079] This invention achieves efficient separation, purification, and recovery of different components in a polymer mixture by sequentially using a settling tank 2, a scraped-film evaporator 5, and a high-efficiency multi-stage distillation column. It not only solves the problems of unstable equipment operation and difficulty in achieving long-term continuous production in existing PGA production processes, but also overcomes the problem of low material recovery rates caused by incomplete solvent separation of various components. First, natural settling is achieved in the settling tank 2 to remove most of the solid polymer. Then, the scraped-film evaporator 5 further achieves complete separation of the solid and liquid phases and recovers the solid polymer. The filtered liquid solvent is then sequentially passed through multiple distillation columns to complete the separation and purification of solvents such as MG, heavy polyols, methanol, and formic acid, ultimately ensuring the effective separation and high-purity recovery of different components in the polymer mixture. This significantly improves the stability and efficiency of the production process, while greatly increasing the material recovery rate and reducing production costs, providing a more reliable and cost-effective solution for the industrial production of PGA.

[0080] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0081] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely implementation methods of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A polymer solution separation system characterized by, The system comprises a flash tank (1), a settling tank (2), a first separation column (12), an MG refining column (20), a methanol separation column (27) and a second separation column (33), the flash tank (1), the settling tank (2) and the first separation column (12) are sequentially connected, the MG refining column (20) and the methanol separation column (27) are respectively connected with the first separation column (12) to make the MG taken out from the first separation column (12) side line enter the MG refining column (20), and part of components discharged from the top of the first separation column (12) enter the methanol separation column (27), the second separation column (33) is connected with the methanol separation column (27) to make part of components discharged from the top of the second separation column (33) enter the second separation column (33).

2. The polymer solution separation system of claim 1, wherein, A wiped film evaporator (5) and a heavy liquid tank (6) are sequentially arranged on the flow path between the settling tank (2) and the first separation column (12), the discharge end of the settling tank (2) is communicated with the entering end of the wiped film evaporator (5) to make the mixed liquid overflowed from the settling tank (2) enter the wiped film evaporator (5) after passing through the delivery pump (3) and the basket filter (4), the entering end of the heavy liquid tank (6) is communicated with the lower discharge end of the wiped film evaporator (5), and the lower discharge end of the heavy liquid tank (6) is communicated to the settling tank (2); The upper discharge end of the wiped film evaporator (5) and the upper discharge end of the heavy liquid tank (6) are both communicated to a wiped film evaporation condenser (8), the first discharge end of the wiped film evaporation condenser (8) is communicated with the first separation column (12), and a wiped film vacuum pump (9) is arranged on the flow path therebetween, the second discharge end of the wiped film evaporation condenser (8) is communicated with the first separation column (12), and a wiped film clear liquid tank (10) and a wiped film clear liquid pump (11) are sequentially arranged on the flow path therebetween.

3. The polymer solution separation system of claim 1, wherein, The upper discharge end of the first separation column (12) is communicated to a first column condenser (13) to make the light components in the first separation column (12) enter the first column condenser (13), the condensate discharge end of the first column condenser (13) is sequentially communicated to a first column reflux tank (15) and a first column reflux pump (16), the discharge end of the first column reflux pump (16) is respectively communicated to the first separation column (12) and the methanol separation column (27), the non-condensate gas discharge end of the first column condenser (13) is communicated to a waste gas system, and a first column vacuum pump (14) is arranged on the flow path therebetween; The first side line discharge end of the first separation column (12) is communicated to the MG refining column (20), and a first column side line discharge pump (19) is arranged on the flow path between the first side line discharge end and the MG refining column (20).

4. The polymer solution separation system of claim 1, wherein, A first column circulating loop is arranged on the lower part of the first separation column (12), and a first column reboiler (39) and a first column kettle forced circulation pump (40) are arranged on the first column circulating loop. The bottom discharge end of the first separation tower (12) is communicated to a depolymerization system, and a separation one tower kettle discharge pump (17) and a separation one tower kettle discharge heater (18) are arranged on the flow path therebetween.

5. The polymer solution separation system of claim 1, wherein, The upper discharge end of the MG refining tower (20) is communicated to a refining tower condenser (23) so that the light components in the MG refining tower (20) enter the refining tower condenser (23), the condensed gas discharge end of the refining tower condenser (23) is sequentially communicated to a refining tank reflux tank (25) and a refining tank reflux pump (26), and the discharge end of the refining tank reflux pump (26) is respectively communicated to the MG refining tower (20) and the methanol separation tower (27); the non-condensed gas discharge end of the refining tower condenser (23) is communicated to a waste gas system, and a refining tower vacuum pump (24) is arranged on the flow path therebetween.

6. The polymer solution separation system of claim 1, wherein, One lateral discharge end of the MG refining tower (20) is communicated to a heavy polyol tank, and a refining tower reboiler (41) is arranged on the flow path therebetween; The bottom discharge end of the MG refining tower (20) is communicated to the heavy polyol tank, and a refining tower kettle pump (22) is arranged on the flow path therebetween.

7. The polymer solution separation system of claim 1, wherein, The upper discharge end of the methanol separation tower (27) is communicated to a methanol separation condenser (30) so that the light components in the methanol separation tower (27) enter the methanol separation condenser (30), the condensed gas discharge end of the methanol separation condenser (30) is sequentially communicated to a methanol separation reflux tank (31) and a methanol separation reflux pump (32), and the discharge end of the refining tank reflux pump (26) is respectively communicated to the methanol separation tower (27) and the second separation tower (33); the non-condensed gas discharge end of the methanol separation condenser (30) is communicated to a waste gas system.

8. The polymer solution separation system of claim 1, wherein A methanol separation circulating loop is arranged on the lower part of the methanol separation tower (27), and a methanol separation reboiler (42) is arranged on the methanol separation circulating loop; The bottom discharge end of the methanol separation tower (27) is communicated to a mixed alcohol tank, and a methanol separation tower kettle pump (28) and a methanol separation tower kettle cooler (29) are arranged on the flow path therebetween.

9. The polymer solution separation system of claim 8, wherein, The upper discharge end of the second separation tower (33) is communicated to a separation two tower condenser (36) so that the light components in the second separation tower (33) enter the separation two tower condenser (36), the condensed gas discharge end of the separation two tower condenser (36) is sequentially communicated to a separation two tank reflux tank (37) and a separation two tank reflux pump (38), and the discharge end of the separation two tank reflux pump (38) is respectively communicated to the second separation tower (33) and the mixed alcohol tank; the non-condensed gas discharge end of the separation two tower condenser (36) is communicated to a waste gas system, and a separation two tower vacuum pump is arranged on the flow path therebetween.

10. The polymer solution separation system of claim 1, wherein, A separation two tower circulating loop is arranged on the lower part of the second separation tower (33), and a separation two tower reboiler (43) is arranged on the separation two tower circulating loop; The bottom discharge end of the second separation tower (33) is communicated to a methanol buffer tank and a ring unit buffer tank, and a separation two tower kettle discharge pump (34) and a separation two tower kettle cooler (35) are arranged on the flow path therebetween.

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