A coarse glycolide recrystallization drying system

Abstract

The utility model discloses a kind of coarse glycolide recrystallization drying systems, it includes recrystallization unit, drying unit, packing machine.Occupation: when drying unit fails, glycolide can be sent into packing system vacuum packing into bag and is refrigerated storage, prevent metamorphic;When drying unit is re-used, refrigerated glycolide can be handled through recrystallization unit or drying unit and reused, reduce the waste of material.And, drying unit and its related pipeline can be cleaned by solvent, solve residual glycolide metamorphic, and then save the replacement problem of unqualified glycolide before drying unit re-start, shorten qualified product output time, reduce unnecessary energy consumption, improve product yield.

Description

Technical Field

[0001] This utility model relates to the field of crude glycolide refining technology, and in particular to a crude glycolide recrystallization and drying system. Background Technology

[0002] The crude lactide refining system is mainly used to purify crude lactide. The system primarily includes the following units: a pretreatment unit, which dissolves solid crude lactide in a specific solvent (such as ethyl acetate or acetone) by heating; a decolorization and purification unit, which adds adsorbents such as activated carbon to the solution and removes colored impurities and some residual metal catalysts through stirring and filtration; a recrystallization unit, which utilizes the difference in solubility between lactide and impurities in a specific solvent to allow high-purity lactide to crystallize from the solution through cooling and solvent evaporation, while most impurities remain in the mother liquor; a separation unit, which separates the precipitated pure lactide crystals from the mother liquor containing impurities using a centrifuge; a drying unit, which dries the separated lactide crystals to remove the solvent; and a solvent recovery unit, which recovers and recycles the solvent, reducing production costs and environmental impact. The above system has the following problems: the drying unit has a high failure rate. When the drying unit fails, it is necessary to disconnect the pipelines between the drying unit and the recrystallization unit and the subsequent system, and to clear the blockage and discharge the material locally. This results in the deterioration of a large amount of glycolide discharged from the front-end recrystallization unit and a large amount of qualified glycolide discharged from the drying unit (glycolide exposed to air for a long time will react with water in the air, and the self-polymerization reaction is faster when the temperature is above 0°C), which is a waste. In addition, glycolide will remain in the equipment and pipelines of the drying unit. During maintenance, it will deteriorate into unqualified glycolide upon contact with air. In the early stage of restarting, a large amount of qualified glycolide is needed to replace the remaining unqualified glycolide, which consumes a large amount of qualified glycolide and leads to a long start-up time, which prolongs the production time of qualified products. Utility Model Content

[0003] The purpose of this invention is to provide a crude glycolide recrystallization and drying system to solve the problems existing in the prior art.

[0004] This utility model is implemented by the following technical solution: a crude lactide recrystallization and drying system, comprising a recrystallization unit and a drying unit, wherein the outlet of the recrystallization unit is connected to the inlet of the drying unit via a connecting pipe, and the outlet of the drying unit is connected to a refined lactide discharge pipe; the system also includes a packaging machine, wherein a first control valve is installed on the refined lactide discharge pipe, and the side of the connecting pipe is connected to the inlet of the packaging machine via a first branch pipe; the refined lactide discharge pipe on the inlet side of the first control valve is connected to the first branch pipe on the inlet side of the packaging machine via a second branch pipe; a second control valve is installed on the first branch pipe; a third control valve is installed on the connecting pipe between the second control valve and the inlet of the drying unit; and a fourth control valve is installed on the second branch pipe.

[0005] Furthermore, it also includes a hot melt agent storage tank and a collection tank. The outlet of the hot melt agent storage tank is connected to the discharge port of the recrystallization unit through a connecting pipe between the hot melt pipe and the second control valve. A sixth control valve is installed on the hot melt pipe. A fifth control valve is installed on the first branch pipe between the second branch pipe and the inlet of the packaging machine. The first branch pipe between the fifth control valve and the second branch pipe is connected to the inlet of the collection tank through a collection pipe. A seventh control valve is installed on the collection pipe.

[0006] Furthermore, the collection tank is connected to the inlet of the solvent recovery unit, and the outlet of the solvent recovery unit is connected to the inlet of the hot melt storage tank.

[0007] The advantages of this invention are as follows: When the drying unit malfunctions, the glycolide can be vacuum-packed into bags and refrigerated to prevent spoilage. When the drying unit is put back into use, the refrigerated glycolide can be recycled through the recrystallization or drying unit, reducing material waste. Furthermore, the drying unit and its related pipelines can be cleaned with solvents to prevent residual glycolide from spoiling, thus eliminating the need to replace substandard glycolide before restarting the drying unit, shortening the time to produce qualified products, reducing unnecessary energy consumption, and improving product yield. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the overall structure of this embodiment.

[0009] In the picture: 1. Recrystallization unit; 2. Drying unit; 3. Packaging machine; 4. Hot melt agent storage tank; 5. Collection tank; 6. Connecting pipe; 7. Refined lactide discharge pipe; 8. First control valve; 9. First branch pipe; 10. Second branch pipe; 11. Second control valve; 12. Third control valve; 13. Fourth control valve; 14. Hot melt pipe; 15. Sixth control valve; 16. Fifth control valve; 17. Collection pipe; 18. Seventh control valve; 19. Solvent recovery unit. Detailed Implementation

[0010] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0011] like Figure 1 As shown, a crude glycolide recrystallization and drying system includes a recrystallization unit 1, a drying unit 2, a packaging machine 3, a hot melt agent storage tank 4, and a collection tank 5. The recrystallization unit 1 and the drying unit 2 are based on the recrystallization and drying methods in the crude glycolide refining system in the prior art, and this utility model is merely an application of them.

[0012] The discharge port of recrystallization unit 1 is connected to the inlet of drying unit 2 through connecting pipe 6. The discharge port of drying unit 2 is connected to refined glycolide discharge pipe 7. A first control valve 8 is installed on refined glycolide discharge pipe 7. The side of connecting pipe 6 is connected to the inlet of packaging machine 3 through first branch pipe 9. The refined glycolide discharge pipe 7 on the inlet side of the first control valve 8 is connected to the first branch pipe 9 on the inlet side of packaging machine through second branch pipe. A second control valve 11 is installed on the first branch pipe 9, and a third control valve 12 is installed on the connecting pipe 6 between the second control valve 11 and the inlet of the drying unit 2; a fourth control valve 13 is installed on the second branch pipe 10.

[0013] The outlet of the hot melt agent storage tank 4 is connected to the discharge port of the recrystallization unit 1 via the hot melt pipe 14 and the second control valve 11 through the connecting pipe 6. A sixth control valve 15 is installed on the hot melt pipe 14. A fifth control valve 16 is installed on the first branch pipe 9 between the second branch pipe 10 and the inlet of the packaging machine 3. The first branch pipe 9 between the fifth control valve 16 and the second branch pipe 10 is connected to the inlet of the collection tank 5 via the collection pipe 17. A seventh control valve 18 is installed on the collection pipe 17.

[0014] The collection tank 5 is connected to the inlet of the solvent recovery unit 19, and the outlet of the solvent recovery unit 19 is connected to the inlet of the hot melt storage tank 4. The solvent recovery unit 19 is based on the solvent recovery method in the crude glycolide refining system in the prior art. This utility model is just an application of it.

[0015] Work process description: When the drying unit is operating normally, the second control valve 11, the sixth control valve 15, the fourth control valve 13, the fifth control valve 16, and the seventh control valve 18 are kept closed, while the third control valve 12 and the first control valve 8 are opened. The glycolide processed by the recrystallization unit 1 enters the drying unit 2 through the connecting pipe for drying. The refined glycolide obtained after drying is discharged to the subsequent equipment through the refined glycolide discharge pipe 7.

[0016] When the drying unit malfunctions, the first control valve 8 and the third control valve 12 are closed, and the second control valve 11, the fifth control valve 16, and the fourth control valve 13 are opened. The glycolide discharged from the recrystallization unit 1 and the glycolide remaining in the drying unit 2 are discharged into the packaging system through the first branch pipe 9 and the second branch pipe 10, respectively, and vacuum-packed into bags. Then, they are stored under refrigeration conditions. When the drying unit 2 is repaired, the refrigerated glycolide can be put into the inlet of the recrystallization unit or the drying unit for recrystallization or drying to achieve the reuse of glycolide. After the glycolide packaging is completed, first close the fourth control valve 13 and the fifth control valve 16, and open the sixth control valve 15 and the seventh control valve 18. The solvent stored in the hot melt agent storage tank 4 flows through the connecting pipe, the first branch pipe 9, and the collection pipe 17 into the collection tank 5. Then, close the second control valve 11 and open the third control valve 12 and the fourth control valve 13. The solvent stored in the hot melt agent storage tank 4 flows through the connecting pipe 6, the drying unit 2, the refined glycolide discharge pipe 7, and the second branch pipe 10, and then enters the collection tank 5 through the collection pipe 17 for storage. Through the above operations, the drying unit 2 and its related pipelines can be cleaned with solvent to ensure that all glycolide is discharged, thereby saving the problem of replacing unqualified glycolide before restarting the drying unit, shortening the production time of qualified products, reducing unnecessary energy consumption, and improving product yield. The material collected in the collection tank 5 is sent to the solvent recovery unit 19 for solvent recovery. The recovered solvent can be sent back to the hot melt agent storage tank 4 for storage, realizing the recycling of solvent.

[0017] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "front", "rear", "top", "bottom", "left", "right", "vertical", "horizontal", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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 utility model.

Claims

1. A crude glycolide recrystallization and drying system, comprising a recrystallization unit and a drying unit, wherein the outlet of the recrystallization unit is connected to the inlet of the drying unit via a connecting pipe, and the outlet of the drying unit is connected to a refined glycolide discharge pipe, characterized in that, It also includes a packaging machine, on which a first control valve is installed; the side of the connecting pipe is connected to the inlet of the packaging machine via a first branch pipe; the lactide discharge pipe on the inlet side of the first control valve is connected to the first branch pipe on the inlet side of the packaging machine via a second branch pipe; a second control valve is installed on the first branch pipe; a third control valve is installed on the connecting pipe between the second control valve and the inlet of the drying unit; and a fourth control valve is installed on the second branch pipe.

2. The crude glycolide recrystallization and drying system according to claim 1, characterized in that, It also includes a hot melt agent storage tank and a collection tank. The outlet of the hot melt agent storage tank is connected to the discharge port of the recrystallization unit through a connecting pipe between the hot melt pipe and the second control valve. A sixth control valve is installed on the hot melt pipe. A fifth control valve is installed on the first branch pipe between the second branch pipe and the inlet of the packaging machine. The first branch pipe between the fifth control valve and the second branch pipe is connected to the inlet of the collection tank through a collection pipe. A seventh control valve is installed on the collection pipe.

3. The crude glycolide recrystallization and drying system according to claim 2, characterized in that, The collection tank is connected to the inlet of the solvent recovery unit, and the outlet of the solvent recovery unit is connected to the inlet of the hot melt storage tank.

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