Glycolide separation and purification system

Abstract

The utility model provides a glycolide separation and purification system, which comprises a solid-liquid separation all-in-one machine, a mother liquor collecting tank, N-1 or N washing liquor collecting tanks and a drying device, a washing area and a drying area in the solid-liquid separation all-in-one machine are arranged between a filtering area and a discharging area, the filtering area is provided with a slurry feeding port, the discharging area is provided with a solid discharging port, and the washing area and the drying area are communicated with each other. The washing area is provided with a washing solvent inlet; the mother liquor collecting tank is connected with a liquid discharging pipe of the filtering area; one washing liquid collecting tank is connected with a liquid discharging pipe of one washing area, the liquid discharging pipe of the first-stage washing area is connected with the mother liquid collecting tank or the first washing liquid collecting tank, the liquid discharging pipe of the nth-stage washing area is connected with the nth washing liquid collecting tank, and the nth washing liquid collecting tank is connected with a washing solvent inlet of the (n-1) th-stage washing area through a circulating pump; the drying device is connected with the drying area. According to the utility model, the solid-liquid separation all-in-one machine is adopted to carry out multi-stage serial washing on the wet filter cake, a good washing effect is achieved through a small amount of washing solvent, and meanwhile, crystal loss is reduced.

Description

Technical Field

[0001] The utility model relates to the field of chemical purification devices, in particular to a glycolide separation and purification system. Background Art

[0002] In the prior art, cyclic esters (such as lactide, glycolide, etc.) can be used as monomers for preparing degradable materials (such as polylactide, polyglycolide, etc.), and the preparation process of cyclic esters has received more and more attention.

[0003] Typically, in the process steps for preparing cyclic esters, it is necessary to separate and purify the crude cyclic esters (e.g., crude glycolide, crude lactide, etc.) to remove impurities therein before using them in the subsequent ring-opening polymerization process. Currently, the separation and purification of cyclic esters generally requires steps such as washing, filtering, and drying to remove impurities therein. To achieve these steps, it is generally necessary to use a process unit that combines multiple equipment such as a washing kettle / washing tank, a vacuum centrifuge, and a dryer / drying kettle, which occupies a large area. Washing the wet filter cake requires the use of a large amount of washing solvent.

[0004] In view of this, the inventors of the present application designed a glycolide separation and purification system in order to overcome the above technical problems. Utility Model Content

[0005] The technical problem to be solved by the utility model is to overcome the defects of large amount of washing solvent used and large equipment footprint in the prior art for separating and purifying glycolide, and to provide a glycolide separation and purification system.

[0006] The utility model solves the above technical problems through the following technical solutions:

[0007] A glycolide separation and purification system is characterized in that the glycolide separation and purification system comprises:

[0008] An integrated solid-liquid separator, comprising a filtration zone, N-stage washing zones, at least one drying zone, and a discharge zone, wherein the washing zone and the drying zone are arranged between the filtration zone and the discharge zone, the filtration zone is provided with a slurry feed port, the discharge zone is provided with a solid discharge port, and each stage of the washing zone is provided with a washing solvent inlet, wherein N is greater than or equal to 2;

[0009] a mother liquor collection tank connected to a drain pipe of the filtration zone;

[0010] N-1 or N washing liquid collection tanks, one of the washing liquid collection tanks is connected to the drain pipe of one of the washing zones, wherein the drain pipe of the first-stage washing zone is connected to the mother liquor collection tank or the first washing liquid collection tank, the drain pipe of the n-stage washing zone is connected to the n-th washing liquid collection tank, and the n-th washing liquid collection tank is further connected to the washing solvent inlet of the n-1-stage washing zone via a circulation pump, wherein the value of n ranges from 2 to N;

[0011] A drying device is connected to the drying zone and is used to dry the wet filter cake entering the drying zone.

[0012] According to one embodiment of the present invention, a plurality of drying zones are provided, and at least one drying zone is provided after the N washing zones;

[0013] The drain pipe of the drying zone is connected to a collection tank connected to the filtering zone or washing zone provided before the drying zone, and the collection tank is a gas-liquid separation tank;

[0014] Alternatively, the glycolide separation and purification system further comprises at least one independently provided gas-liquid separation tank, and the gas-liquid separation tank is connected to a drain pipe of the drying zone.

[0015] According to one embodiment of the present utility model, the drying device is a nitrogen circulation drying device, the gas outlet of the nitrogen circulation drying device is connected to the gas inlet of the drying zone, and after the gas-liquid mixture generated in the drying zone enters the gas-liquid separation tank, the low-pressure nitrogen discharged from the gas-liquid separation tank flows back into the gas supply pipeline of the nitrogen circulation drying device through the booster and the circulation pipeline.

[0016] According to one embodiment of the present invention, the glycolide separation and purification system further includes a pre-dehumidification device, which is connected to the washing zone and is used to pre-dehumidify the wet filter cake entering the washing zone.

[0017] According to one embodiment of the present invention, the glycolide separation and purification system also includes a filter cloth cleaning device, the solid-liquid separation integrated machine is provided with a cleaning liquid inlet after the solid discharge port of the discharge area, the filter cloth cleaning device is connected to the cleaning liquid inlet, and the discharge pipe of the discharge area is connected to the mother liquor collection tank or the washing liquid collection tank.

[0018] According to one embodiment of the present invention, the glycolide separation and purification system also includes a glycolide slurry storage tank, one pipeline of the glycolide slurry storage tank's outlet is connected to the slurry feed port of the solid-liquid separation integrated machine through a delivery pump, and the other pipeline is used for self-regulation.

[0019] According to one embodiment of the present invention, the solid-liquid separation integrated machine includes:

[0020] A housing and a drum, wherein the drum is rotatably arranged in the housing around the axis of the housing, a surface of the drum is provided with a plurality of compartments, and a filter unit is installed in each of the compartments;

[0021] a distribution head, the distribution head being arranged outside the rotary drum, the rotary drum rotating relative to the housing and the distribution head, the distribution head being provided with liquid collection areas corresponding to the filtration area, the washing area, the drying area, and the discharge area, respectively, and the distribution head being provided with drainage pipes corresponding one to one to the liquid collection areas;

[0022] The solid-liquid separation integrated machine is connected to the mother liquid collection tank and the washing liquid collection tank through different drainage pipes.

[0023] According to one embodiment of the present invention, the filter unit includes a filter plate, a flexible mesh isolation pad and a filter cloth, the flexible mesh isolation pad is arranged on the filter plate, and the filter cloth is arranged on the flexible mesh isolation pad.

[0024] According to one embodiment of the present invention, an adjusting gasket is provided at the bottom of the filter plate, and the depth of the filter plate in the compartment is adjusted by adjusting the number and / or thickness of the adjusting gasket.

[0025] According to one embodiment of the present invention, the angle between the compartment and the axis of the shell is 0° to 5°.

[0026] The positive progress effect of this utility model is:

[0027] The glycolide separation and purification system of the utility model adopts a solid-liquid separation integrated machine to perform multi-stage series washing on the wet filter cake. The equipment occupies a small area, and the washing liquid discharged from the latter washing area is returned to the previous washing area for use as a washing solvent. A good washing effect can be achieved with a small amount of washing solvent, while reducing crystal loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which the same reference numerals represent the same features throughout, wherein:

[0029] Figure 1 This is a structural diagram of the glycolide separation and purification system of the utility model.

[0030] Figure 2 This is a structural diagram of the solid-liquid separation integrated machine in the glycolide separation and purification system of the present invention.

[0031] Figure 3 This is a schematic diagram of the angle between the axis of the compartment chamber and the shell of the solid-liquid separation integrated machine in the glycolide separation and purification system of the present invention. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0033] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Reference will now be made in detail to preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to represent the same or similar parts.

[0034] In addition, although the terms used in the present invention are selected from well-known and commonly used terms, some terms mentioned in the specification of the present invention may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article.

[0035] Furthermore, it is required that the present invention be understood not only by the actual terms used but also by the meanings connoted by each term.

[0036] like Figure 1 As shown, the present invention discloses a glycolide separation and purification system, which includes a solid-liquid separation integrated machine 10, a mother liquor collection tank 20, and N-1 or N washing liquid collection tanks 30 (N is greater than or equal to 2). Among them, the solid-liquid separation integrated machine 10 includes a filtration zone, N-stage washing zones, at least one drying zone, and a discharge zone. The washing zone and the drying zone are arranged between the filtration zone and the discharge zone, and at least one drying zone is arranged after the N washing zones, that is, the material must be dried at least once after being washed N times before being discharged. When multiple drying zones are provided, the position of the drying zone can be arranged in a variety of ways, for example: arranged between two adjacent washing zones, or arranged after all washing zones, or arranged after the filtration zone and before the washing zone; as long as at least one drying zone is arranged after the N washing zones and before the discharge zone. Therefore, the arrangement of multiple drying zones can be adjusted according to actual needs, all within the scope of protection of this application, and will not be described in detail here.

[0037] In the integrated solid-liquid separator 10, the filtration zone is provided with a slurry feed port, the discharge zone is provided with a solid discharge port, and each washing zone is provided with a washing solvent inlet. The mother liquor collection tank 20 is connected to the drainage pipe of the filtration zone and is used to store the mother liquor obtained from the glycolide slurry through the filtration zone. The drainage pipe of the first-stage washing zone can be connected to the mother liquor collection tank 20 or the first washing liquid collection tank 30. The washing liquid produced by the first washing enters the mother liquor collection tank 20 or the first washing liquid collection tank 30 from the first-stage washing zone. Starting from the second-stage washing zone, the drainage pipe of each washing zone is connected to the washing liquid collection tank 30. The washing liquid produced by the n-th washing enters the n-th washing liquid collection tank 30 from the n-th washing zone. The washing liquid in the n-th washing liquid collection tank 30 also flows into the washing solvent inlet of the n-1-stage washing zone through a circulation pump and is used as the washing solvent of the n-1-stage washing zone in the subsequent separation and purification process, where n is 2 to N.

[0038] The drain pipe of the drying zone is connected to the collecting tank connected to the filtering zone or washing zone arranged before the drying zone, so that the gas-liquid mixture generated in the drying zone enters the collecting tank connected to the filtering zone or washing zone arranged before the drying zone. The collecting tank is a gas-liquid separation tank, which can play a role in gas-liquid separation of the gas-liquid mixture generated in the drying zone.

[0039] Specifically, when the drying zone is arranged after the filtering zone, the drain pipe of the drying zone is connected to the mother liquor collection tank 20 connected to the filtering zone, and the gas-liquid mixture generated in the drying zone enters the mother liquor collection tank 20 from the drying zone, and the mother liquor collection tank is a gas-liquid separation tank; when the drying zone is arranged after the first-level washing zone, the drain pipe of the drying zone is connected to the mother liquor collection tank 20 connected to the first-level washing zone (N-1 washing liquid collection tanks are arranged at this time) or the first washing liquid collection tank 30 (N washing liquid collection tanks are arranged at this time); when the drying zone is arranged after the n-th washing zone, the drain pipe of the drying zone is connected to the n-th washing liquid collection tank 30, and the mother liquor collection tank 10 or the washing liquid collection tank connected to the drying zone is a gas-liquid separation tank.

[0040] For example, Figure 1 In the illustrated embodiment, the arrangement within the integrated solid-liquid separator 10 is a first-stage washing zone - a second-stage washing zone - a drying zone. The washing liquid produced in the first-stage washing zone enters a first washing liquid collection tank 30, and the washing liquid produced in the second-stage washing zone enters a second washing liquid collection tank 30. After the second washing, the gas-liquid mixture produced by drying the wet filter cake in the drying zone also enters the second washing liquid collection tank 30, which serves as a gas-liquid separation tank.

[0041] Alternatively, the glycolide separation and purification system may further include at least one independently arranged gas-liquid separation tank, wherein a gas-liquid separation tank is connected to a drying zone, and the gas-liquid mixture generated in the drying zone enters the gas-liquid separation tank connected thereto. It should be noted that the number of independently arranged gas-liquid separation tanks and the number of drying zones do not necessarily correspond.

[0042] For example, the layout within the integrated solid-liquid separator 10 is a 1-stage washing zone - drying zone - 2-stage washing zone - drying zone. The washing liquid produced in the 1-stage washing zone enters the first washing liquid collection tank 30. After the first washing, the gas-liquid mixture produced by drying the wet filter cake in the drying zone also enters the first washing liquid collection tank, which serves as a gas-liquid separation tank. The washing liquid produced in the 2-stage washing zone enters the 2-stage washing liquid collection tank. After the second washing, the gas-liquid mixture produced by drying the wet filter cake in the drying zone enters a separately provided gas-liquid separation tank.

[0043] Furthermore, the glycolide separation and purification system also includes a drying device, which is connected to the drying zone and is used to dry the wet filter cake entering the drying zone. The drying method can be airflow drying or vacuum drying. When airflow drying is adopted, drying gas (for example, nitrogen or inert gas) is injected into the drying zone at a certain pressure (for example, 0.2-0.5MPa) through the gas inlet of the drying zone to dry the wet filter cake in the drying zone. The drying gas squeezes the filter cake while a small part passes through the wet filter cake and takes out the moisture in the wet filter cake. The resulting gas-liquid mixture enters the corresponding gas-liquid separation tank; when vacuum drying is adopted, the gas-liquid separation tank connected to the drying zone is connected to an external vacuum pump through a pipeline and a condenser. The vacuum pump evacuates the drying zone to vacuum dry the wet filter cake in the drying zone, and the resulting gas-liquid mixture enters the corresponding gas-liquid separation tank.

[0044] As a preferred solution, the drying device is a nitrogen circulation drying device, the gas outlet of the nitrogen circulation drying device is connected to the gas inlet of the drying zone, the gas-liquid mixture generated in the drying zone enters the gas-liquid separation tank for gas-liquid separation, and the low-pressure nitrogen discharged from the gas-liquid separation tank is refluxed to the gas supply pipeline of the nitrogen circulation drying device through the booster 31 and the circulation pipeline to reduce the loss of nitrogen and washing solvent.

[0045] Furthermore, the glycolide separation and purification system may further include a pre-dehumidification device connected to the scrubbing zone for pre-dehumidifying the wet filter cake entering the scrubbing zone. Similarly, the pre-dehumidification method may be nitrogen drying or vacuum drying. Preferably, the pre-dehumidification device is a nitrogen drying device, with the gas outlet of the nitrogen drying device connected to the gas inlet of the scrubbing zone.

[0046] The glycolide separation and purification system further includes a discharge device, which is connected to or disposed in correspondence with the discharge area of ​​the solid-liquid separator 10. The discharge device may include a discharge backflush device and / or a scraper discharge device (not shown). For example, the discharge device includes a discharge backflush device, the backflush gas outlet of which is in communication with the interior of the discharge area. By backflush gas (e.g., nitrogen) into the discharge area, the dried filter cake is discharged from the discharge area and flows out of the solid discharge port.

[0047] As a preferred solution, the glycolide separation and purification system further includes a filter cloth cleaning device. The solid-liquid separator is provided with a cleaning liquid inlet after the solid discharge port in the discharge zone. The filter cloth cleaning device is connected to the cleaning liquid inlet. The discharge pipe in the discharge zone is connected to the mother liquor collection tank 20 or any washing liquid collection tank 30. The filter cloth cleaning liquid flowing out of the discharge zone can enter the mother liquor collection tank 20 or any washing liquid collection tank 30. The filter cloth cleaning device may include a cleaning liquid storage tank and a delivery pump.

[0048] As a preferred solution, the glycolide separation and purification system further includes a glycolide slurry storage tank (e.g., a crystallizer, a collection tank, a washing tank, etc.). One pipeline from the glycolide slurry storage tank outlet is normally transported to the slurry feed port of the solid-liquid separation integrated machine via a delivery pump, and another pipeline is used for self-regulation. For example, a self-regulating valve is provided on the pipeline to adjust the load or self-circulate back to the collection tank under abnormal conditions, thereby improving the feasibility of the operation and the ability to resist risks. The glycolide slurry can be a solid-liquid mixture after glycolide crystallization or a solid-liquid mixture after glycolide melt is cooled by a liquid medium.

[0049] like Figure 2 As shown, the above-mentioned solid-liquid separation integrated machine 10 includes: a shell 12, a drum 13 and a manifold 14. The drum 13 is rotatably arranged in the shell 12 around the axis of the shell 12, and an annular chamber is formed between the drum 13 and the shell 12. A plurality of compartments 130 are provided on the surface of the drum 13, each of which is equipped with a filter unit. A filter hole is provided at the bottom of the compartment 130, and the filter hole is connected to a flow pipe. The manifold 14 is fixed in the inner cavity of the drum 13 and rotates together with the drum 13. The manifold 14 is fixedly connected to the discharge end of each flow pipe.

[0050] A distribution head 131 is provided on the outside of the drum 13, and the drum 13 rotates relative to the housing 12 and the distribution head 131. The discharge outlet of the manifold 14 extends into the distribution head 131. The distribution head 131 is provided with liquid collection areas corresponding to the above-mentioned filtration area, washing area, drying area, and discharge area, respectively. The distribution head 131 is also provided with drainage pipes corresponding to the above-mentioned liquid collection areas. The drainage pipes are used to discharge the liquid from the corresponding liquid collection areas and to connect the corresponding liquid collection areas to the outside (for example, to an external vacuum pump connection pipe). The solid-liquid separation integrated machine 10 is connected to the mother liquor collection tank 20 and the washing liquid collection tank 30 via different drainage pipes.

[0051] Furthermore, the solid-liquid separation integrated machine 10 also includes a plurality of first seals and a plurality of second seals (not shown in the figure). The first seal is arranged between the shell 12 and the drum 13, and is used to divide the annular chamber into the above-mentioned filtration area, N washing areas, at least one drying area and a discharge area. The second seal is arranged between the collecting pipe 14 and the distribution head 131, and is used to separate the distribution head 131 into liquid collection areas corresponding to the above-mentioned filtration area, washing area, drying area, and discharge area. It can be understood that when the drain pipes of adjacent liquid collection areas are connected to the same collection tank, the second seal in the distribution head can be cancelled. Therefore, the number of second seals does not have to correspond to the first seals. For example, Figure 1 In the embodiment shown, the washing liquid produced by the second-stage washing and the gas-liquid mixture produced in the drying zone enter the same separation tank, and the liquid collecting areas corresponding to the second-stage washing zone and the drying zone can be connected.

[0052] Specifically, the filter unit includes a filter plate, a flexible mesh isolation pad, and a filter cloth. The flexible mesh isolation pad is disposed on the filter plate, and the filter cloth is disposed on the flexible mesh isolation pad. The filter plate is a perforated steel plate. The flexible mesh isolation pad can reduce damage to the filter plate, thereby extending the service life of the filter plate.

[0053] Preferably, the filter unit is removably mounted within the compartment 130. Adjustable shims are provided at the bottom of the filter plate. By adjusting the number and / or thickness of the shims, the depth of the filter plate within the compartment 130, and therefore the thickness of the filter cake layer, can be adjusted to accommodate changes in production. For example, the thickness of each shim can be 2 mm. By increasing or decreasing the number of shims, the height of the filter layer and the depth of the filter plate cavity can be adjusted.

[0054] Preferably, if Figure 3 As shown, the angle between compartment 130 and the axis of housing 12 is 0° to 5°, meaning compartment 130 is tilted 0° to 5° horizontally. The axis of housing 12 is preferably horizontal. This structural arrangement effectively reduces wear on the device and multiple first seals caused by pressure fluctuations, extending service life.

[0055] As described above, the purification method using the glycolide separation and purification system of the present invention includes the following steps:

[0056] First, glycolide slurry from the glycolide slurry storage tank is pumped into the solid-liquid separator via a transfer pump. It is then injected into the filtration zone's cavity through the slurry inlet at a constant pressure (e.g., 0.1-0.6 MPa), filling each compartment within the cavity. Under this pressure differential, the liquid in the solid-liquid mixture passes through the filter unit, passing through the filter holes, flow tubes, and manifolds into the corresponding liquid collection area within the distribution head. It is then discharged through a drain pipe to a mother liquor collection tank, where the solid components of the solid-liquid mixture remain as a filter cake on the filter unit.

[0057] As the drum rotates, the compartment chamber loaded with filter cake enters the next treatment zone from the filtration zone, passes through N (N is greater than or equal to 2) washing zones and at least one drying zone, and finally enters the discharge zone and is discharged from the solid discharge port of the discharge zone.

[0058] When a compartment loaded with filter cake is in the washing zone, a washing solvent is injected into the chamber through the liquid inlet at a certain pressure (e.g., 0.05-0.5 MPa). This wash solvent cleans the filter cake on the filter elements within the compartment. The impurity-laden washing liquid flows through the filter holes, flow tubes, and manifolds into the corresponding liquid collection area within the distribution head, where it is discharged through the drain pipe. The washing liquid generated in the n-stage washing zone is discharged into the n-stage washing liquid collection tank. A liquid distributor (e.g., a perforated plate liquid distributor) is provided at the washing solvent inlet to ensure uniform distribution of the liquid over the filter cake. In particular, the filter cake can be pre-dehumidified.

[0059] When the filter cake-laden compartment is in the drying zone, the gas-liquid mixture produced in the drying zone flows through the filter holes, flow tubes, and manifolds into the corresponding liquid collection area within the distribution head. The mixture is then discharged through the drain pipe into the wash liquid collection tank, where the wash liquid from the most recent wash cycle is discharged. Specifically, multiple drying zones can be arranged adjacent to each other, forming a multi-stage drying system.

[0060] When the compartment chamber loaded with filter cake is in the unloading area, the filter cake is discharged by backblowing (backblowing air pressure 0.01-0.15MPa) and equipped with a movable scraper when necessary. After the filter cake is discharged, the filter cloth is flushed (flushing pressure 0.05-0.6MPa), and the filter cloth cleaning liquid is discharged to the mother liquor collection tank or any level washing liquid collection tank.

[0061] After being washed by the filter cloth, the compartment chamber rotates back to the cavity area of ​​the filtration zone to separate and purify the next batch of glycolide solid-liquid mixture. The washing liquid in the nth level washing liquid collection tank is used as the washing solvent for the (n-1)th washing zone after passing through the circulation pump.

[0062] Based on the structural description of the glycolide separation and purification system and the description of the purification method, the following is further explained through a specific example:

[0063] The feed consists of a solid-liquid mixture of glycolide crystallized from ethyl acetate. The mass fraction of solid glycolide in the crystallized liquid is 15%. The feed temperature is 5°C. The glycolide slurry is conveyed to the filtration zone of the solid-liquid separator at a pressure of 0.3 MPa. The separator has 12 compartments, each with a 10mm filter layer height and a rotational speed of 20 rpm. The processing capacity of the glycolide slurry is 1.44 t / h.

[0064] The glycolide slurry is filtered, washed, washed, and dried in the solid-liquid separator before being discharged. The washing solvent is injected into the washing solvent inlet of the washing zone at a pressure of 0.3 MPa. The washing solvent in the first and second washing zones is initially pure ethyl acetate. The amount of washing solvent used at each stage is 1 times the mass of the filter cake to be washed. The resulting washing liquid flows into the first and second washing liquid collection tanks respectively.

[0065] In the drying area, nitrogen at 40°C is injected as drying gas at a pressure of 0.3 MPa, and the resulting gas-liquid mixture flows into the second washing liquid collection tank, which is a gas-liquid separation tank.

[0066] In the discharge area, nitrogen is back-flushed from the corresponding liquid collection area in the distribution head to the discharge area at a pressure of 0.02MPa for unloading. Then, filter cloth cleaning liquid (ethyl acetate is also used) is injected at a pressure of 0.2MPa, and the resulting filter cloth washing liquid flows into the second washing liquid collection tank.

[0067] This cycle was repeated. When the liquid level in the second washing liquid collection tank reached above 50%, the washing liquid in the second washing liquid collection tank was pumped to the washing solvent inlet of the first washing zone via a circulation pump and used as the washing solvent in the first washing zone. After reaching stable production, the glycolide output rate was 224 kg / h. The final glycolide filter cake had a moisture content of 9% and an acidity of ≤60 ppm.

[0068] The glycolide separation and purification system of the present invention adopts a solid-liquid separation integrated machine to perform multi-stage series washing on the wet filter cake. The equipment occupies a small area and collects the washing liquid discharged from each washing area respectively. The washing liquid discharged from the latter washing area is returned to the previous washing area for use as a washing solvent, which reduces the use of solvent and reduces crystal loss.

[0069] In addition, the glycolide separation and purification system of the present invention has the following advantages:

[0070] 1. Nitrogen drying can be done in one or more stages. The gas-liquid mixture produced in the drying area enters the gas-liquid separation tank. After gas-liquid separation, the low-pressure nitrogen enters the booster (screw compressor or liquid ring compressor can be used) and is reused after boosting and heat exchange, thereby reducing the loss of nitrogen and washing solvent.

[0071] 2. The feed slurry distribution pipes are evenly distributed, which can effectively avoid dead zones and reduce blockages. Equal distribution pipes and large radius elbows are set according to the properties of the materials.

[0072] 3. Each compartment is tilted horizontally by 0 to 5 degrees to reduce the wear of the equipment and multiple first seals caused by pressure fluctuations and extend the service life.

[0073] 4. The purification system has stepless speed regulation, and the areas occupied by each treatment zone can be inconsistent.

[0074] For those skilled in the art, the above disclosure is intended to be illustrative only and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and amendments to this application. Such modifications, improvements, and amendments are suggested in this application and remain within the spirit and scope of the exemplary embodiments of this application.

[0075] At the same time, this application uses specific terms to describe the embodiments of this application. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "one embodiment," "an embodiment," or "an alternative embodiment" mentioned twice or multiple times in different locations in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application may be appropriately combined.

[0076] Similarly, it should be noted that, in order to simplify the description of the present disclosure and thus facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of the present disclosure sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not mean that the subject matter of the present disclosure requires more features than those recited in the claims. In fact, the features of an embodiment may be fewer than the total features of a single embodiment disclosed above.

[0077] Although specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative and that the scope of protection of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications shall fall within the scope of protection of the present invention.

Claims

1. A glycolide separation and purification system, characterized in that: The glycolide separation and purification system comprises: An integrated solid-liquid separator, comprising a filtration zone, N-stage washing zones, at least one drying zone, and a discharge zone, wherein the washing zone and the drying zone are arranged between the filtration zone and the discharge zone, the filtration zone is provided with a slurry feed port, the discharge zone is provided with a solid discharge port, and each stage of the washing zone is provided with a washing solvent inlet, wherein N is greater than or equal to 2; a mother liquor collection tank connected to a drain pipe of the filtration zone; N-1 or N washing liquid collection tanks, one of the washing liquid collection tanks is connected to the drain pipe of one of the washing zones, wherein the drain pipe of the first-stage washing zone is connected to the mother liquor collection tank or the first washing liquid collection tank, the drain pipe of the n-stage washing zone is connected to the n-th washing liquid collection tank, and the n-th washing liquid collection tank is further connected to the washing solvent inlet of the n-1-stage washing zone via a circulation pump, wherein the value of n ranges from 2 to N; A drying device is connected to the drying zone and is used to dry the wet filter cake entering the drying zone.

2. The glycolide separation and purification system according to claim 1, wherein: There are multiple drying zones, and at least one drying zone is arranged after the N washing zones; The drain pipe of the drying zone is connected to a collection tank connected to the filtering zone or washing zone provided before the drying zone, and the collection tank is a gas-liquid separation tank; Alternatively, the glycolide separation and purification system further comprises at least one independently provided gas-liquid separation tank, and the gas-liquid separation tank is connected to a drain pipe of the drying zone.

3. The glycolide separation and purification system according to claim 2, wherein: The drying device is a nitrogen circulation drying device, the gas outlet of the nitrogen circulation drying device is connected to the gas inlet of the drying zone, and after the gas-liquid mixture generated in the drying zone enters the gas-liquid separation tank, the low-pressure nitrogen discharged from the gas-liquid separation tank flows back into the gas supply pipeline of the nitrogen circulation drying device through the booster and the circulation pipeline.

4. The glycolide separation and purification system according to claim 3, wherein: The glycolide separation and purification system further comprises a pre-dehumidification device, which is connected to the washing zone and is used for pre-dehumidifying the wet filter cake entering the washing zone.

5. The glycolide separation and purification system according to claim 1, wherein: The glycolide separation and purification system also includes a filter cloth cleaning device. The solid-liquid separation integrated machine is provided with a cleaning liquid inlet after the solid discharge port of the discharge area. The filter cloth cleaning device is connected to the cleaning liquid inlet, and the discharge pipe of the discharge area is connected to the mother liquor collection tank or the washing liquid collection tank.

6. The glycolide separation and purification system according to claim 1, wherein: The glycolide separation and purification system also includes a glycolide slurry storage tank. One pipeline of the glycolide slurry storage tank's outlet is connected to the slurry feed port of the solid-liquid separation integrated machine through a delivery pump, and the other pipeline is used for self-regulation.

7. The glycolide separation and purification system according to any one of claims 1 to 6, characterized in that: The solid-liquid separation integrated machine comprises: A housing and a drum, wherein the drum is rotatably arranged in the housing around the axis of the housing, a surface of the drum is provided with a plurality of compartments, and a filter unit is installed in each of the compartments; a distribution head, the distribution head being arranged outside the rotary drum, the rotary drum rotating relative to the housing and the distribution head, the distribution head being provided with liquid collection areas corresponding to the filtration area, the washing area, the drying area, and the discharge area, respectively, and the distribution head being provided with drainage pipes corresponding one to one to the liquid collection areas; The solid-liquid separation integrated machine is connected to the mother liquid collection tank and the washing liquid collection tank through different drainage pipes.

8. The glycolide separation and purification system according to claim 7, wherein: The filter unit includes a filter plate, a flexible mesh isolation pad and a filter cloth. The flexible mesh isolation pad is arranged on the filter plate, and the filter cloth is arranged on the flexible mesh isolation pad.

9. The glycolide separation and purification system according to claim 8, characterized in that: An adjusting gasket is provided at the bottom of the filter plate, and the depth of the filter plate in the compartment is adjusted by adjusting the number and / or thickness of the adjusting gasket.

10. The glycolide separation and purification system according to claim 7, characterized in that: The included angle between the compartment and the axis of the shell is 0° to 5°.

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