CN114053758B

CN114053758B - Liquid separation device and method for polyester purification

Info

Publication number: CN114053758B
Application number: CN202111181112.8A
Authority: CN
Inventors: 于崆峒; 蒋朝军
Original assignee: Zhejiang Sundoc Pharmaceutical Science And Tech Co ltd
Current assignee: Zhejiang Sundoc Pharmaceutical Science And Tech Co ltd
Priority date: 2021-10-11
Filing date: 2021-10-11
Publication date: 2023-03-31
Anticipated expiration: 2041-10-11
Also published as: CN114053758A

Abstract

The invention discloses a liquid separating device and method for purifying polyester, wherein the device comprises: the liquid separation device comprises a first liquid separation tank, a second liquid separation tank, a flow guide structure, overflow pipes and a pressurizing device, wherein the flow guide structure comprises a plurality of first flow guide pipes and at least one second flow guide pipe, one end of each first flow guide pipe is communicated with the side wall of the first liquid separation tank, the height difference exists between any two first flow guide pipes in the axis direction of the liquid separation tank, the other end of each first flow guide pipe is communicated with the second liquid separation tank through the second flow guide pipe, a first valve is arranged on each first flow guide pipe, a second valve is arranged on each second flow guide pipe, a first-stage clear liquid outlet is arranged on each second flow guide pipe and is positioned between the first valve and the second valve, and a third valve is arranged on the first-stage clear liquid outlet; one end of the overflow pipe extends into the bottom of the second liquid separation tank, and the other end of the overflow pipe is communicated with the first liquid separation tank; the pressurizing device is communicated with the second liquid separation tank; the bottom of the second liquid separation tank is provided with a second-stage clear liquid outlet, and a fourth valve is arranged at the second-stage clear liquid outlet.

Description

Liquid separation device and method for polyester purification

Technical Field

The application relates to the technical field of liquid separation, in particular to a liquid separation device and method for polyester purification.

Background

Biodegradable polyesters have long been widely used for controlled drug delivery, and the polyesters are synthesized by the polycondensation of lactic acid, or lactic acid and glycolic acid, or by the ring-opening polymerization of lactide, or lactide and glycolide. In any synthesis route, by-products such as unconverted monomers and oligomers must be present.

The presence of monomers and oligomers in polyesters is a serious problem, monomers are extremely unstable and rapidly decompose into equivalent acids in high humidity environments, which in turn catalyze the degradation of polyester products, which in turn affects the processing and storage stability of the polyester products. Therefore, the crude polyester needs to be purified. The method commonly used is to dissolve the crude polyester with a good solvent and to remove unreacted monomers and oligomers by adding an excessive amount of a poor solvent to cause precipitation of the polyester.

In the process of implementing the invention, the inventor finds that at least the following problems exist in the prior art:

need separate heavy phase (polyester product) and light phase (solvent mixture) after the polyester purification, workshop splitter divides the liquid mouth of pipe to have fixed, only guarantee to divide the liquid layer to be located accurately and divide the liquid mouth and just can accomplish meticulous separation, but each batch of material output all has the change in actual production, lead to its to divide the liquid layer to change great, can not guarantee to divide the liquid layer just to be in fixed minute mouth department under most circumstances, when dividing the liquid layer to be located between two liquid pipes, lead to heavy phase (polyester product) to store up light phase (solvent mixture), exist oligomer and monomer in the light phase, influence polyester product quality and stability.

If the heavy phase is directly transferred, the high material viscosity of the polyester layer can cause material loss, the liquid surface area of the liquid separating tank is larger, the occupation ratio of the polyester layer is small, the density of the heavy phase and the light phase is close, the disturbance of a liquid separating interface can be easily caused in the liquid level descending process, the heavy phase is doped with the light phase and is discharged together, the product and impurities are not completely separated, and the quality of the polyester product is reduced; if part of the heavy phase layer is discarded, the polyester recovery rate is low, the production cost is increased, and the production benefit is seriously influenced.

Disclosure of Invention

The embodiment of the application aims to provide a liquid separating device and method for purifying polyester, so as to solve the technical problem that products and impurities are not completely separated in the related technology.

According to a first aspect of the embodiments of the present application, there is provided a liquid separation device for purifying polyester, comprising:

a first liquid separation tank and a second liquid separation tank;

the liquid separation device comprises a liquid separation tank, a flow guide structure and a liquid separation tank, wherein the flow guide structure comprises a plurality of first flow guide pipes and at least one second flow guide pipe, one end of each first flow guide pipe is communicated with the side wall of the first liquid separation tank, the height difference exists between any two first flow guide pipes in the axis direction of the liquid separation tank, the other end of each first flow guide pipe is communicated with the second liquid separation tank through the second flow guide pipe, a first valve is arranged on each first flow guide pipe, a second valve is arranged on each second flow guide pipe, a primary clear liquid outlet is formed in each second flow guide pipe and is positioned between the first valve and the second valve, and a third valve is arranged on the primary clear liquid outlet;

one end of the overflow pipe extends into the bottom of the second liquid separation tank, and the other end of the overflow pipe is communicated with the first liquid separation tank; and

the pressurizing device is communicated with the second liquid separation tank;

and a second-stage clear liquid outlet is formed in the bottom of the second liquid separation tank, and a fourth valve is arranged at the second-stage clear liquid outlet.

Furthermore, a stirring paddle is arranged in the first liquid separation tank.

Further, a first spraying ball is arranged in the first liquid separation tank.

Further, a second spraying ball is arranged in the second liquid separation tank.

Further, a first sight glass is arranged on the side wall of the first liquid separation tank.

Further, a second sight glass is arranged on the side wall of the second liquid separation tank.

Further, a fifth valve is arranged on the overflow pipe.

Further, a third sight glass is arranged on the overflow pipe.

Furthermore, the flow guide structure is arranged at 1/10-1/3 of the position below the tank body of the first liquid separation tank.

Further, the distance between the lower end of the overflow pipe and the bottom of the second liquid separation tank is 1-5 mm.

Further, the aspect ratio of the second branch tank is 10.

Further, the tank body of the second liquid separation tank is a pressure-tight tank body, and the pressure resistance value of the second liquid separation tank is more than or equal to 2kg/cm ² 。

Furthermore, the inner diameter of the pipeline of the overflow pipe is 3-5 mm.

Further, the height difference between the bottom of the first liquid separation tank and the bottom of the second liquid separation tank is 300-500 mm.

According to a second aspect of embodiments of the present application, there is provided a liquid separation method for purifying polyester, the method being applied to the apparatus of the first aspect, the method including:

adding the polyester crude product, the organic solvent and the water for injection into the first liquid separation tank, stirring until a polyester layer is precipitated, and standing to enable the polyester phase and the organic solvent/water mixed solvent phase to be layered;

opening a first valve nearest to the upper part of a liquid separation interface of the polyester phase and the organic solvent/water mixed solvent phase, opening a third valve, closing a second valve at the same time, and discharging the organic solvent/water mixed solvent phase in the first liquid separation tank from a primary clear liquid outlet;

after all the organic solvent/water mixed solvent phase which can be discharged through the nearest first flow guide pipe above the liquid separation interface is discharged, closing the nearest first valve and the nearest third valve above the liquid separation interface, simultaneously opening the second valve and the nearest first valve below the liquid separation interface, and allowing the mixed phase consisting of the residual organic solvent/water mixed solvent phase and part of the polyester phase in the first liquid separation tank to enter the second liquid separation tank through the first flow guide pipe and the second flow guide pipe;

after the mixed phase is completely transferred, closing a first valve nearest below the liquid separation interface, and standing the mixed phase in a second liquid separation tank for a period of time until the polyester phase and the organic solvent/water mixed solvent phase are layered again;

pressurizing the second liquid separation tank by a pressurizing device, and returning the polyester phase in the second liquid separation tank to the first liquid separation tank through an overflow pipe;

and discharging the residual organic solvent/water mixed solvent phase in the second separating tank from a secondary clear liquid outlet.

The technical scheme provided by the embodiment of the application can have the following beneficial effects:

according to the embodiment, the liquid separation device is provided with the first liquid separation tank and the second liquid separation tank, so that the light phase and the heavy phase can be accurately separated through two-step liquid separation operation, and all the heavy phase is recovered; a diversion structure is arranged between the first liquid separation tank and the second liquid separation tank, any two of a plurality of first diversion pipes in the diversion structure have height difference in the axis direction of the liquid separation tank, so that a light phase (mixed solvent) can be discharged through a certain first diversion pipe, and the discharged light phase (mixed solvent) and a small amount of mixed heavy phase (polyester product) reach the second liquid separation tank through the second diversion pipe; the pressurizing device pressurizes the second liquid separation tank, and the heavy phase (polyester product) returns to the first liquid separation tank through the overflow pipe, so that the complete separation of the heavy phase (polyester product) and the light phase (mixed solvent) is achieved.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application.

Fig. 1 is a schematic diagram illustrating a structure of a liquid separation device for purifying polyester according to an exemplary embodiment.

The reference numerals in the figures are:

100. a first liquid separation tank; 101. a stirring paddle; 102. a first spray ball; 103. a first sight glass; 104. a feeding port; 105. a liquid discharge port; 106. a return port;

200. a second liquid separation tank; 201. a secondary clear liquid outlet; 202. a fourth valve; 203. a second spray ball; 204. a second sight glass;

300. a flow guide structure; 301. a first draft tube; 302. a second draft tube; 303. a first valve; 304. a second valve; 305. a first-stage clear liquid outlet; 306. a third valve;

400. an overflow pipe; 401. a fifth valve; 402. a third sight glass;

500. a pressurizing device; 502. and a sixth valve.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

It is to be understood that although the terms first, second, third, etc. may be used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present application. The word "if" as used herein may be interpreted as "at" \8230; "or" when 8230; \8230; "or" in response to a determination ", depending on the context.

Fig. 1 is a schematic structural diagram of a liquid separating apparatus for polyester purification according to an exemplary embodiment, as shown in fig. 1, the apparatus may include a first liquid separating tank 100, a second liquid separating tank 200, a flow guiding structure 300, an overflow pipe 400 and a pressurizing device 500, the flow guiding structure 300 includes a plurality of first flow guiding pipes 301 and at least one second flow guiding pipe 302, one end of each first flow guiding pipe 301 is communicated with a side wall of the first liquid separating tank 100, any two first flow guiding pipes 301 have a height difference in an axial direction of the liquid separating tank, the other end of each first flow guiding pipe 301 is communicated with the second liquid separating tank 200 through the second flow guiding pipe 302, a first valve 303 is disposed on each first flow guiding pipe 301, a second valve 304 is disposed on each second flow guiding pipe 302, a first clear liquid outlet 302 is disposed on each second flow guiding pipe 302, the first clear liquid outlet 305 is disposed between the first valve 303 and the second valve 304, and a third valve 306 is disposed on the first clear liquid outlet 305; one end of the overflow pipe 400 extends into the bottom of the second liquid separation tank 200, and the other end is communicated with the first liquid separation tank 100; the pressurizing device 500 is communicated with the second liquid separation tank 200; the bottom of the second separation tank 200 is provided with a secondary clear liquid outlet 201, and a fourth valve 202 is arranged at the secondary clear liquid outlet 201.

From the above embodiments, the present application is provided with the first liquid separation tank 100 and the second liquid separation tank 200, and the light phase and the heavy phase can be separated accurately through two-step liquid separation operation, and all the heavy phase is recovered; a diversion structure 300 is arranged between the first liquid separation tank 100 and the second liquid separation tank 200, any two of a plurality of first diversion pipes 301 in the diversion structure 300 have a height difference in the axis direction of the liquid separation tank, so that a light phase (mixed solvent) can be discharged through a certain first diversion pipe 301, and the discharged light phase (mixed solvent) and a small amount of mixed heavy phase (polyester product) reach the second liquid separation tank 200 through a second diversion pipe 302; the pressurizing device 500 pressurizes the second separation tank 200, and the heavy phase (polyester product) returns to the first separation tank 100 through the overflow pipe 400, so that the heavy phase (polyester product) and the light phase (mixed solvent) are completely separated.

Specifically, the first branch tank 100 generally further comprises a feeding port 104 and a liquid discharging port 105, wherein the feeding port 104 is generally arranged at the top of the first branch tank 100 and is used for feeding materials into the first branch tank 100; the drain port 105 is generally provided at the bottom of the first partial tank 100 for draining the heavy phase (polyester product) in the first partial tank 100.

In an embodiment, the first flow guide pipes 301 are horizontal flow guide pipes which are distributed horizontally at equal intervals in the axial direction of the liquid separation tank.

In an embodiment, the diversion structure 300 includes a plurality of first diversion pipes 301 and a second diversion pipe 302, the other ends of the first diversion pipes 301 are respectively communicated with the second diversion pipe 302, the connection ports of any two first diversion pipes 301 on the second diversion pipe 302 have a height difference, when the heavy phase (polyester product) and the light phase (mixed solvent) in the first liquid separation tank 100 are layered, the light phase is discharged from the primary clear liquid outlet 305 through the first diversion pipe 301 and the second diversion pipe 302 which are nearest above the interface; after the discharge operation of the light phase is completed, the mixed phase of the heavy phase and the light phase is transferred to the second separation tank 200 through the first diversion pipe 301 and the second diversion pipe 302 which are nearest below the divided interface;

in another embodiment, the diversion structure 300 comprises a plurality of first diversion pipes 301 and a plurality of second diversion pipes 302 corresponding to the first diversion pipes 301 one by one, each of the second diversion pipes 302 is provided with a primary clear liquid outlet 305, and when the heavy phase (polyester product) and the light phase (mixed solvent) in the first liquid separation tank 100 are layered, the light phase is discharged from the primary clear liquid outlet 305 through the first diversion pipe 301 and the second diversion pipe 302 which are nearest above the interface; after the discharge operation of the light phase is completed, the mixed phase of the heavy phase and the light phase is transferred to the second separation tank 200 through the first guide pipe 301 and the second guide pipe 302 which are nearest below the dividing surface; most of the supernatant in the first separation tank 100 is removed by a two-step operation, and the heavy phase and the light phase which are not completely separated are introduced into the second separation tank 200, and in both embodiments, the process can be realized by the combination of the first flow guide pipe 301 and the second flow guide pipe 302.

Specifically, the overflow pipe 400 communicates with the first liquid-separation tank 100 through a return port 106 provided in a side wall of the first liquid-separation tank 100.

In an embodiment, the pressurizing device 500 is communicated with the second separation tank 200 through the second flow guiding pipe 302, in this case, a sixth valve 502 can be disposed between the pressurizing device 500 and the first valve 303, and the pressurizing device 500 performs a pressurizing operation on the second separation tank 200, so that the heavy phase (polyester product) returns to the first separation tank 100 through the flow guiding pipe 400;

in another embodiment, the pressurizing device 500 is directly communicated with the second branch tank 200, and the pressurizing device 500 performs pressurizing operation on the second branch tank 200, so that the heavy phase (polyester product) returns to the first branch tank 100 through the overflow pipe 400;

in both of the above embodiments, the heavy phase (polyester product) can be returned to the first branch tank 100 through the overflow pipe 400 by the pressurizing device 500, and the pressurizing device 500 is located upstream of the second branch tank 200, and the location is not particularly limited.

In an embodiment, a stirring paddle 101 is disposed inside the first separation tank 100, and the stirring paddle 101 can be used for stirring the liquid in the first separation tank 100, so that the polyester synthesis is complete.

In an embodiment, a first spraying ball 102 is disposed inside the first liquid separation tank 100, and the first spraying ball 102 can satisfy the functions of online cleaning and online sterilization. The second spraying ball 203 is arranged in the second liquid separation tank 200, and the second spraying ball 203 can meet the functions of online cleaning and online sterilization.

In an embodiment, a first sight glass 103 is disposed on a side wall of the first liquid separation tank 100, the first sight glass 103 can be used for observing the condition inside the first liquid separation tank 100 and distinguishing a liquid separation limit according to a scale on the first sight glass 103 so as to open a corresponding first valve 303, and when the side wall of the first liquid separation tank 100 is transparent, the first sight glass 103 may not be disposed on the side wall of the first liquid separation tank 100.

In an embodiment, a second viewing mirror 204 is disposed on a sidewall of the second separation tank 200, the second viewing mirror 204 can be used for observing the inside condition of the second separation tank 200, and when the sidewall of the second separation tank 200 is transparent, the second viewing mirror 204 may not be disposed on the sidewall of the second separation tank 200.

In one embodiment, a fifth valve 401 is provided on the overflow tube 400. The fifth valve 401 is used for isolating the first liquid separation tank 100 from the second liquid separation tank 200, preventing the materials in the polyester purification stage from being introduced into the second-stage liquid separation tank and the accessory devices, and opening after the second-stage liquid separation is finished, so as to reintroduce the polyester phase into the first liquid separation tank 100.

In an embodiment, a third viewing mirror 402 is disposed on the overflow pipe 400, the third viewing mirror 402 is disposed on the overflow pipe 400 near the first liquid separation tank 100, and can be used to observe whether the heavy phase is completely transferred during the second liquid separation process, and when the overflow pipe 400 is transparent, the first viewing mirror 103 may not be disposed on the overflow pipe 400.

In one embodiment, the diversion structure 300 is disposed 1/10 to 1/3 of the bottom of the first liquid separation tank 100. When the mixed solvent is adopted for polyester purification, usually the water phase is a large-volume phase, the organic solvent is a small-volume phase, most of the organic solvent is extracted by water after the polyester is purified, kept stand and separated, so that the volume ratio of the polyester phase is low, and the first guide pipe 301 is positioned at 1/10-1/3 of the lower part of the tank body so as to realize effective separation.

In one embodiment, the distance between the lower end of the overflow pipe 400 and the bottom of the second separation tank 200 is 1-5 mm; specifically, the distance between the lower end of the overflow pipe 400 and the bottom of the tank not only affects the heavy phase transfer residue, but also affects the disturbance states of the heavy phase and the light phase when the interface sinks, so that the distance is reduced, the material liquid residue can be reduced, and the interface clarity is increased, preferably 1-5 mm, and more preferably 2mm.

In one embodiment, the height-diameter ratio of the second liquid separation tank 200 is 10; specifically, the design can reduce the two-phase contact area of the feed liquid with the same volume, thereby increasing the separation effect, and the increase of the height-diameter ratio of the second liquid separation tank 200 is the same as the ratio, so that the total length of the overflow pipe 400 is also increased, and in order to achieve the ideal liquid separation effect and simultaneously reduce the pipeline loss of the overflow pipe 400 as much as possible, the ratio is more preferably 8.

In one embodiment, the tank body of the second branch tank 200 is a pressure-tight tank body, and the pressure resistance value of the second branch tank 200 is not less than 2kg/cm ² So that the second separation tank 200 can bear the pressure of the pressurizing device 500, so that the mixed phase in the second separation tank 200 can be separated, and the heavy phase can return to the first separation tank 100 through the overflow pipe 400, thereby completing the secondary separation.

In one embodiment, the overflow tube 400 has a tube inner diameter of 3 to 5mm; specifically, the inner diameter of the overflow pipe 400 influences the stable transportation of the heavy-phase polyester residue and the feed liquid, and after exploration, when the inner diameter is less than 5mm, the extremely low heavy-phase residue can be realized, the light-phase heavy phase slowly descends, and the interface is always kept clear; when the inner diameter is less than 3mm, the feed liquid transfer resistance is increased, and thus the inner diameter of the overflow pipe 400 is preferably 3 to 5mm, more preferably 4mm.

In one embodiment, the height difference between the bottom of the first branch tank 100 and the bottom of the second branch tank 200 is 300-500 mm. The height difference can realize the slow transfer of the mixed phase of the heavy phase and the light phase from the first liquid separation tank 100 to the second liquid separation tank 200, when the height difference is higher than the height difference, the heavy phase and the light phase can be seriously disturbed, the secondary liquid separation time is prolonged, and when the height difference is lower than the height difference, the transfer is difficult.

In an embodiment, the liquid separation device provided in this embodiment is suitable for a case where a target phase to be obtained is a heavy phase, especially for a case where density of the heavy phase and density of the light phase are not much different, and it is specifically required that a density ratio of the separated heavy phase and density of the separated light phase is greater than or equal to 1.05. The conventional liquid separation is that the heavy phase is directly discharged from a lower discharge port, and especially when the density ratio of the heavy phase to the light phase is close, the liquid and the liquid are not completely separated easily, and the heavy phase and the light phase can be accurately separated even if the density ratio of the heavy phase to the light phase is as low as 1.05.

The application also provides a liquid separation method for purifying polyester, which can be applied to any device in the text description and comprises the following steps:

step S11: adding the polyester crude product, the organic solvent and the water for injection into the first liquid separation tank 100, stirring until a polyester layer is precipitated, and standing to separate the polyester phase from the organic solvent/water mixed solvent phase;

specifically, the organic solvent is a hydrophilic organic solvent, in this embodiment, acetone, and 5kg of crude polyester is added into the first liquid separation tank 100 from the feeding port 104, and then 40L of acetone is added, and stirred by the stirring paddle 101 until the crude polyester is completely dissolved; continuously stirring, slowly adding 30L of water for injection from a feeding port 104 into the first liquid separation tank 100 until a polyester layer is precipitated; standing for 30min to allow the polyester phase and the acetone/water mixed solvent phase to separate.

Step S12: opening a first valve 303 nearest to the liquid separation interface of the polyester phase and the organic solvent/water mixed solvent phase, opening a third valve 306, closing a second valve 304 at the same time, and discharging the organic solvent/water mixed solvent phase in the first liquid separation tank 100 from a primary clear liquid outlet 305;

specifically, the position of the liquid separation interface of the polyester phase and the acetone/water mixed solvent phase is obtained through the scale of the first sight glass 103, the first valve 303 nearest above the liquid separation interface of the polyester phase and the acetone/water mixed solvent phase is opened, the second valve 304 is opened, and the third valve 306 is closed, so that most of the acetone/water mixed solvent phase in the first liquid separation tank 100 can be discharged from the primary clear liquid outlet 305 through the first flow guide pipe 301 and the second flow guide pipe 302 nearest above the liquid separation interface.

Step S13: after all the organic solvent/water mixed solvent phase which can be discharged through the first diversion pipe 301 nearest to the upper part of the liquid separation interface is discharged, the first valve 303 and the third valve 306 nearest to the upper part of the liquid separation interface are closed, the second valve 304 and the first valve 303 nearest to the lower part of the liquid separation interface are opened at the same time, and the mixed phase consisting of the residual organic solvent/water mixed solvent phase and part of polyester phase in the first liquid separation tank 100 enters the second liquid separation tank 200 through the first diversion pipe 301 and the second diversion pipe 302;

specifically, after all of the acetone/water mixed solvent phase discharged through the first flow guide 301 nearest to the liquid separation interface is discharged, the polyester phase and a small amount of the acetone/water mixed solvent phase are present in the first liquid separation tank 100, and the mixed phase of the acetone/water mixed solvent phase and a small amount of the polyester phase in the first liquid separation tank 100 is transferred to the second liquid separation tank 200 through the first flow guide 301 and the second flow guide 302 nearest to the liquid separation interface.

Step S14: after the mixed phase is completely transferred, closing the nearest first valve 303 below the liquid separation interface, and standing the mixed phase in the second liquid separation tank 200 for a period of time until the polyester phase and the organic solvent/water mixed solvent phase are layered again;

specifically, after the mixed phase is completely transferred to the second liquid separation tank 200, the mixed phase is allowed to stand to cause the polyester phase and the acetone/water mixed solvent phase to be separated again for the second liquid separation operation.

Step S15: pressurizing the second branch tank 200 by a pressurizing device 500, and returning the polyester phase in the second branch tank 200 to the first branch tank 100 through an overflow pipe 400;

specifically, the sixth valve 502 is opened, the second partial tank 200 is pressurized by the pressurizing device 500, the polyester phase in the second partial tank 200 is returned to the first partial tank 100 through the overflow pipe 400 under the pressure, whether the polyester phase in the second partial tank 200 is completely transferred or not is observed by the third sight glass 402, and when the polyester phase is completely transferred, the fifth valve 401 is closed to completely and intensively separate all the polyester phases into the first partial tank 100 and perform the subsequent drying operation.

Step S16: the remaining organic solvent/water mixed solvent phase in the second separation tank 200 is discharged from the secondary clear liquid outlet 201.

Specifically, after the polyester phase in the second separation tank 200 returns to the first separation tank 100 through the overflow pipe 400, only the acetone/water mixed solvent phase in the second separation tank 200 is discharged from the second separation tank 200 through the secondary clear liquid outlet 201.

Example 1:

referring to fig. 1, an embodiment of the present invention provides a liquid separation device for polyester purification, including a first liquid separation tank 100, a feeding port 104 disposed at the top of the tank body, a return port 106 disposed at the side wall of the tank body, a liquid discharge port 105 disposed at the bottom of the tank body, and a stirring paddle 101 disposed in the tank body, wherein a first sight glass 103 is disposed on the side wall of the tank body, a plurality of horizontal first guide pipes 301 are disposed at 1/10-1/3 below the tank body, a plurality of first valves 303 for opening or closing the guide pipes are disposed on the first guide pipes 301, the plurality of first guide pipes 301 are horizontally distributed at equal intervals, the left end surface of the first guide pipe 301 is communicated with the first liquid separation tank 100, the right end surface is communicated with a second guide pipe 302, the second guide pipe 302 is a T-shaped pipeline, the upper end surface thereof is connected with a pressure device, the middle thereof is provided with a sixth valve 502 for opening or closing the pressure device, and the lower end surface thereof is a primary clear liquid outlet 305, the middle of the overflow pipe 400 is provided with a third valve 306 for opening or closing a first-stage clear liquid outlet 305, the right end surface of the overflow pipe is communicated with the upper end of the second liquid separation tank 200, the middle of the overflow pipe 400 is provided with a second valve 304 for opening or closing an inlet of the second liquid separation tank 200, the first guide pipe 301 and the second guide pipe 302 are communicated with the first liquid separation tank 100 and the second liquid separation tank 200 together, the side wall of the second liquid separation tank 200 is provided with a second sight glass 204, the bottom of the second liquid separation tank 200 is provided with a second-stage clear liquid outlet 201, the opening or closing of the second liquid separation tank is controlled by a fourth valve 202, the center of the top of the second liquid separation tank 200 is penetrated by an overflow pipe 400 for communicating the first liquid separation tank 100 and the second liquid separation tank 200, the lower end surface of the overflow pipe 400 is positioned above the bottom of the second liquid separation tank 200, the upper end surface of the overflow pipe 400 is communicated with a return port 106 of the first liquid separation tank 100, and the return pipe 400 is provided with a third sight glass 402 and a fifth valve 401.

Example 2:

the embodiment of the invention provides a liquid separation method for polyester purification, which comprises the following steps:

(1) 5kg of crude polyester is added into a first liquid separation tank 100 from a feeding port 104 at the top of the tank, and then 40L of acetone is added and stirred until the crude polyester is completely dissolved;

(2) Continuing to start stirring, and slowly adding 30L of water for injection from a feeding port 104 at the top of the tank until a polyester layer is precipitated;

(3) Standing for 30min to allow the polyester phase and the acetone/water mixed solvent phase to be layered;

(4) Primary liquid separation: according to the scale on the first sight glass 103, the separating limit is identified, the first valve 303 which is nearest above the polyester layer is opened, the third valve 306 is opened, meanwhile, the second valve 304 and the sixth valve 502 are closed, and the supernatant phase in the first separating tank 100 is discharged from the primary clear liquid outlet 305 under the action of gravity;

(5) Secondary liquid separation: after all the clear liquid is discharged, closing the nearest first valve 303 above the polyester layer, closing the third valve 306, simultaneously opening the second valve 304, the fifth valve 401 and the nearest first valve 303 below the polyester layer, allowing the polyester phase and the supernatant phase in the first liquid separation tank 100 to enter the second liquid separation tank 200 through the first flow guide pipe 301 and the second flow guide pipe 302, after all the mixed phase is transferred, closing the nearest first valve 303 below the polyester layer, and allowing the mixed phase to stand in the second liquid separation tank 200 for a period of time until the polyester phase and the supernatant phase are layered again. Opening the second valve 304, the fifth valve 401 and the sixth valve 502, keeping the other valves in a closed state, introducing a pressure source from the upper end of the second guide pipe 302, continuously moving down the liquid interface in the second liquid separation tank 200 under the action of the pressure, returning the polyester phase to the return port 106 again through the overflow pipe 400, observing by the third sight glass 402 until the heavy phase is completely transferred, closing the fifth valve 401, and discharging the residual supernatant of the second liquid separation tank 200 through the second-stage clear liquid outlet 201 below the second liquid separation tank.

The rest of the feed liquid in the first liquid separation tank 100 is all polyester phase, 15L of acetone is added from a feeding port 104, the mixture is continuously stirred and dissolved, and then the mixture is transferred to a downstream process through a liquid outlet 105 for granulation and drying. 4.67kg of co-extruded polyester finished product after drying, and the detection results of the monomers and the oligomers in the polyester finished product are as follows:

batch number	Glycolide	Lactide	Lactic acid	Glycolic acid
					S-210502	Not detected out	0.05％	Not detected out	Not detected out

Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.

It will be understood that the present application is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims

1. A liquid separating device for purifying polyester is characterized by comprising:

a first liquid separation tank and a second liquid separation tank;

the pressurizing device is communicated with the second liquid separation tank;

and a second-stage clear liquid outlet is formed in the bottom of the second separation tank, and a fourth valve is arranged at the second-stage clear liquid outlet.

2. The apparatus according to claim 1, wherein a stirring paddle is arranged inside the first liquid separation tank.

3. The apparatus of claim 1, wherein a first spray ball is disposed within the first constituent tank.

4. The device of claim 1, wherein a second spray ball is arranged inside the second separation tank.

5. The apparatus of claim 1, wherein a side wall of the first cut-liquid tank is provided with a first sight glass.

6. The apparatus according to claim 1, characterized in that a second sight glass is provided to a side wall of the second separation tank.

7. The device of claim 1, wherein a fifth valve is disposed on the overflow tube.

8. The device of claim 1, wherein a third sight glass is disposed on the overflow tube.

9. The device according to claim 1, characterized in that the diversion structure is arranged 1/10-1/3 below the tank body of the first liquid separation tank.

10. The apparatus of claim 1, wherein the distance between the lower end of the overflow pipe and the bottom of the second separation tank is 1 to 5mm.

11. The device according to claim 1, wherein the height/diameter ratio of the second branch tank is 10.

12. The device as claimed in claim 1, wherein the tank body of the second branch tank is a pressure-tight tank body, and the pressure resistance value of the second branch tank is more than or equal to 2kg/cm ² 。

13. The device of claim 1, wherein the overflow tube has a tube inner diameter of 3 to 5mm.

14. The apparatus according to claim 1, wherein a height difference between the bottom of the first separation tank and the bottom of the second separation tank is 300 to 500mm.

15. A liquid separation method for polyester purification, wherein the method is applied to the apparatus of any one of claims 1 to 14, and the method comprises:

opening a first valve nearest to the liquid separation interface of the polyester phase and the organic solvent/water mixed solvent phase, opening a third valve, closing the second valve at the same time, and discharging the organic solvent/water mixed solvent phase in the first liquid separation tank from a primary clear liquid outlet;

and discharging the residual organic solvent/water mixed solvent phase in the second separation tank from a secondary clear liquid outlet.