Separation and decolorization system and separation and decolorization method for regenerated DMT

Abstract

The invention discloses a separating and decolorizing system for regenerated DMT, which comprises a plurality of separating and decolorizing units and a melting storage unit, the plurality of separating and decolorizing units are sequentially connected in series through pipelines, the melting storage unit is connected in series to the rear channel of the last separating and decolorizing unit through a pipeline, and each separating and decolorizing unit comprises a centrifugal separator, a DMT dilution tank and a condensation treatment device. The centrifugal separator is provided with a material input port, a liquid phase outlet, a solid phase outlet and a gas phase outlet, the liquid phase outlet is connected with a separated liquid output pipeline, the solid phase outlet is connected with a DMT dilution tank pipeline, the gas phase outlet is connected with a condensation treatment device pipeline, the condensation treatment device is provided with a backflow pipeline, and the backflow pipeline is connected with the liquid phase outlet of the centrifugal separator. According to the invention, three stages of separation and decoloration units connected in series are designed, the decoloration and purification effects on the DMT coarse material product are realized through three times of separation and dilution operations, the pipeline blockage fault problem in the system operation can be effectively solved, and the stable, continuous and efficient operation of the system is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of regenerated DMT production, and more particularly to a regenerated DMT separation and decolorization system and a separation and decolorization method thereof. Background Art

[0002] The chemical recycling method is a technical means of recycling waste textiles (mainly composed of polyester fiber materials, about 90% or more) to recycle waste textiles. The chemical recycling method requires a series of processes such as textile sorting, crushing, depolymerization, concentration, and ester exchange. After the ester exchange process, a crude material containing DMT can be obtained. However, due to the complex sources of waste textiles, the DMT crude material obtained from them will contain various impurities such as dyes and oils. The presence of impurities makes the DMT crude material product have poor hue, and due to the low purity of DMT, it cannot be directly used for development and utilization. Therefore, DMT is not suitable for recycling. Decolorization and purification of MT crude material is a necessary step for the industrial application of recycled DMT. The use of centrifugal equipment to decolorize and purify DMT crude material products is the current method. How to layout the centrifugal equipment to obtain better decolorization and purification quality is a difficulty in technical research. In addition, a large amount of separation impurities will be produced during the centrifugal operation. These separation impurities will accumulate in the system pipeline and cause pipe blockage. Pipe blockage will lead to production stagnation and affect product quality. Therefore, in the technical improvement of the existing centrifugal equipment system, the timely discovery and elimination of pipe blockage is also a research focus and difficulty. Enterprises need to improve and design a separation and decolorization equipment system for recycled DMT that can operate stably and efficiently to meet production needs. Summary of the Invention

[0003] The present invention aims to address the needs of the prior art by providing a separation and decolorization system for regenerated DMT and a separation and decolorization method thereof. The present invention is designed with three-stage separation and decolorization units connected in series, and achieves the decolorization and purification effect of the DMT crude product through three separation and dilution operations. The present invention is designed with an anti-clogging structure on the key equipment, which can promptly detect and effectively resolve pipeline blockage problems during system operation, ensuring the stable, continuous and efficient operation of the regenerated DMT separation and decolorization system.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A separation and decolorization system for regenerating DMT comprises several separation and decolorization units and a melting storage unit, wherein the several separation and decolorization units are sequentially connected in series with pipelines, and the pipeline of the melting storage unit is connected in series after the last separation and decolorization unit. The separation and decolorization units comprise a centrifuge, a DMT dilution tank and a condensation processing device, wherein the centrifuge is provided with a material input port, a liquid phase outlet, a solid phase outlet and a gas phase outlet, the liquid phase outlet is connected to a separation liquid output pipeline, the solid phase outlet is connected to a DMT dilution tank pipeline, the gas phase outlet is connected to a condensation processing device pipeline, the condensation processing device is provided with a reflux pipeline, the reflux pipeline is connected to the liquid phase outlet of the centrifuge, the DMT dilution tank outlet pipeline of the preceding separation and decolorization unit is connected to the material input port of the centrifuge of the following separation and decolorization unit, and the DMT dilution tank outlet pipeline of the last separation and decolorization unit is connected to the melting storage unit.

[0006] Furthermore, the number of separation and decolorization units is three, the liquid phase outlet of the centrifuge is in an inverted cone shape, the separated liquid output pipeline includes a drain pipe and a first liquid outlet pump, the upper end of the drain pipe is uprightly inserted into the liquid phase outlet, the lower end of the drain pipe is connected to the inlet of the first liquid outlet pump, the top opening of the drain pipe forms a height difference with the bottom of the cone tip of the liquid phase outlet, and the centrifuge is installed with a cleaning pipeline.

[0007] Furthermore, a first partition is fixedly installed in the liquid phase outlet, and a first liquid level detection cavity is formed in the liquid phase outlet by the first partition. A first liquid level gauge is installed in the first liquid level detection cavity. The first liquid level gauge adopts a float type liquid level gauge. The first liquid level detection cavity is connected with the inner cavity of the liquid phase outlet at the lower end.

[0008] Furthermore, a first valve and a first backflush line are installed on the connecting pipeline between the discharge pipe and the first liquid outlet pump. The first valve is installed close to the inlet of the first liquid outlet pump, and the first backflush line and the first valve are opened and closed using interlocking control.

[0009] Furthermore, a methanol input pipeline is connected to the side of the DMT dilution tank, a spray mechanism is installed in the DMT dilution tank, the methanol input pipeline is connected to the spray mechanism, and the outlet of the DMT dilution tank is located at the bottom of the DMT dilution tank.

[0010] Furthermore, the condensation treatment device includes a condenser, which is provided with a gas phase inlet and a first condensate outlet. The gas phase outlet pipeline of the centrifuge is connected to the gas phase inlet of the condenser, one end of the reflux pipeline is connected to the first condensate outlet of the condenser, and the other end of the reflux pipeline is connected to the liquid phase outlet of the centrifuge.

[0011] Furthermore, a U-shaped bend is provided on the reflux pipeline, and a replenishing liquid pipeline is provided on the U-shaped bend. The inlet end and the outlet end of the U-shaped bend are provided according to the flow direction of the condensate in the U-shaped bend. A second valve is installed at the inlet end of the U-shaped bend, and a second backflush pipeline is connected to the outlet end of the U-shaped bend. A third valve is installed on the connecting pipeline between the outlet end of the U-shaped bend and the liquid phase outlet of the centrifuge. The second backflush pipeline, the second valve and the third valve are opened and closed by interlocking control.

[0012] Furthermore, the first condensate outlet of the condenser is connected to a recoil auxiliary box, which includes a box body, a second partition and a third partition. The top of the box body is connected to the first condensate outlet, the box body is provided with a second condensate outlet, the second condensate outlet is staggered with the first condensate outlet, the inlet end pipeline of the U-shaped bend is connected to the second condensate outlet, the second condensate outlet is provided with a filter in the box body, the second partition is installed in the box body, a second liquid level detection cavity is formed in the box body through the second partition, the bottom of the second liquid level detection cavity is connected to the inner cavity of the box body, a second liquid level gauge is installed in the second liquid level detection cavity, the third partition is fixedly installed in the box body, and only the bottom edge of the third partition does not contact the inner wall of the box body. A diffuser cone is fixedly installed in the box body, the diffuser cone is installed with the cone tip facing downward, the diffuser cone is arranged directly above the second condensate outlet, the third partition is arranged on the side of the diffuser cone, and the recoil auxiliary box is provided with cleaning ports on the side and bottom surfaces.

[0013] Furthermore, the molten storage unit includes a heater and a heat preservation storage tank connected in series, the heater inlet pipeline is connected to the DMT dilution tank outlet, and the heater outlet is connected to the heat preservation storage tank pipeline.

[0014] A method for separating and decolorizing regenerated DMT is implemented using a system for separating and decolorizing regenerated DMT, comprising the following steps:

[0015] (a) The crude DMT produced by the transesterification reaction is transported to the first separation and decolorization unit through a pipeline. The crude DMT is transported to a centrifuge through a pipeline. After centrifugal separation, the liquid material is discharged from the separation liquid output pipeline through the liquid phase outlet, and the solid material is output to the DMT dilution tank through the solid phase outlet. The solid material is washed and diluted in the DMT dilution tank to form a first diluted DMT solution. The gaseous material is output to a condensation treatment device through the gas phase outlet. The condensate is refluxed to the liquid phase outlet through the reflux pipeline and then merged and output from the separation liquid output pipeline;

[0016] (b) The diluted DMT solution in the DMT dilution tank of the first separation and decolorization unit is transported to the centrifuge of the second separation and decolorization unit through a series pipeline, and step (a) is repeated to form a further diluted DMT solution in the DMT dilution tank of the second separation and decolorization unit;

[0017] (c) The diluted DMT solution in the DMT dilution tank of the second separation and decolorization unit is transported to the centrifuge of the third separation and decolorization unit through a series pipeline, and step (a) is repeated to form a third diluted DMT solution in the DMT dilution tank of the third separation and decolorization unit;

[0018] (d) The diluted DMT solution in the DMT dilution tank of the second separation and decolorization unit is transported to the molten storage unit through a series pipeline. The DMT solution is first heated by a heater to form a molten state, and then the molten DMT solution is transported to the insulated storage tank for insulated storage.

[0019] The beneficial effects of the present invention are:

[0020] 1. The present invention is designed with three-stage separation and decolorization units connected in series. Through three separation and dilution operations, the decolorization and purification effect of the DMT crude product is achieved (methanol dilution can clean DMT crystals, and the separation operation can rely on methanol liquid to remove impurities). The present invention has the advantages of good decolorization and purification effect and stable quality.

[0021] 2. The present invention is designed with an anti-blocking structure on key equipment, which can timely discover and effectively solve the pipeline blockage problem during system operation, ensuring that the regenerated DMT separation and decolorization system can operate stably, continuously and efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the overall structure of a separation and decolorization system for regenerating DMT in this embodiment;

[0023] Figure 2 Schematic diagram of the structure of the separation and decolorization unit in this embodiment;

[0024] Figure 3 1 is a front view of the internal structure of the liquid phase outlet of the centrifuge in this embodiment;

[0025] Figure 4 1 is a side view of the internal structure of the liquid phase outlet of the centrifuge in this embodiment;

[0026] Figure 5 : is a structural principle diagram of the condensation processing device in this embodiment;

[0027] Figure 6 Schematic diagram of the internal structure of the recoil assist box in this embodiment.

[0028] Reference numerals: separation and decolorization unit 100, melt storage unit 200, heater 201, heat preservation storage tank 202, centrifuge 1, material input port 11, liquid phase outlet 12, first partition plate 121, first liquid level detection chamber 122, first liquid level gauge 123, solid phase outlet 13, gas phase outlet 14, cleaning pipeline 15, separation liquid output pipeline 2, drain pipe 21, first liquid outlet pump 22, first valve 23, first backflush pipeline 24, DMT dilution tank 3, methanol input pipeline 31, spray Shower mechanism 32, condensation processing device 4, condenser 41, gas phase inlet 411, first condensate outlet 412, reflux pipeline 42, U-shaped bend 421, replenishing liquid pipeline 422, second valve 423, second backflush pipeline 424, third valve 425, backflush auxiliary box 43, box body 431, second condensate outlet 432, filter 433, second partition 434, second liquid level detection chamber 435, second liquid level gauge 436, third partition 437, diffuser cone 438, cleaning port 439. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] like Figures 1-6The separation and decolorization system for regenerating DMT shown in the figure includes several separation and decolorization units 100 and a melt storage unit 200. The several separation and decolorization units 100 are connected in series in a pipeline. The separation and decolorization units 100 achieve decolorization and purification of the DMT crude material through solid-liquid separation operation. This is because the main components of the DMT crude material are methanol liquid, DMT crystals and impurities. Most of the impurities are soluble in the methanol liquid. The solid-liquid separation operation of the methanol liquid and the DMT crystals can remove a large amount of impurities (impurities are removed by the methanol liquid). After a large amount of impurities are separated and removed, the color quality and purity of the remaining DMT product will be greatly improved. In order to ensure the decolorization and purification effect and control the production cost of the product, the number of separation and decolorization units 100 actually used is three. The three separation and decolorization units 100 are connected in series. After the DMT crude material undergoes three consecutive repeated separation and decolorization operations, its color quality and purity meet the production design requirements (DMT crude material product The product turns black. After passing through the three separation and decolorization units 100, the obtained DMT product is light gray, which indicates that the decolorization and purification are obvious and can meet the needs of subsequent distillation operations. The molten storage unit 200 pipeline is connected in series to the downstream of the last separation and decolorization unit 100. The molten storage unit 200 includes a heater 201 and an insulation storage tank 202 connected in series. The inlet pipeline of the heater 201 is connected to the last separation and decolorization unit 100, and the outlet of the heater 201 is connected to the insulation storage tank 202 pipeline. The DMT product after three decolorization and purification is first input into the heater 201 for heating, so that the DMT crystals are heated to a molten state. The molten DMT is dissolved in fresh methanol to form a solution, and then output to the insulation storage tank 202 for storage. The outer wall of the insulation storage tank 202 is provided with an insulation layer to ensure that the DMT remains in a molten state. The downstream of the insulation storage tank 202 is connected to the distillation operation equipment, and the DMT product can be output to the distillation operation equipment for the next processing as needed. Figure 2As shown, in the present invention, the separation and decolorization unit 100 includes a centrifuge 1, a DMT dilution tank 3 and a condensation treatment device 4. The centrifuge 1 used in the present invention is a commercially available drum centrifugal separation equipment, which is a prior art and has a structural principle that will not be introduced in detail. The centrifuge 1 is provided with a material input port 11, a liquid phase outlet 12, a solid phase outlet 13 and a gas phase outlet 14. The material enters the centrifuge 1 from the material input port 11. When the drum rotates at high speed, the liquid is thrown out from the drum and collected at the liquid phase outlet 12 for output, while the separated solid is pushed to the solid phase outlet 13 for output by the screw conveying mechanism. Volatile gas will also be generated during the centrifugal separation process, and the gas will be output from the gas phase outlet 14. The liquid separated by centrifugation is mainly The component is methanol and is entrained with impurities. These methanol liquids need to be centrally reused. Therefore, the liquid phase outlet 12 is connected to the separation liquid output pipeline 2, and the separated methanol liquid is output through the separation liquid output pipeline 2. The solid separated by centrifugation is DMT crystals. The color and purity of these DMT crystals are not ideal. Therefore, the present invention connects the solid phase outlet 13 to the DMT dilution tank 3 pipeline, and the DMT crystals are directly discharged into the DMT dilution tank 3. The side of the DMT dilution tank 3 is connected to the methanol input pipeline 31. The methanol input pipeline 31 can replenish the DMT dilution tank 3 with fresh high-purity methanol liquid. The DMT dilution tank 3 is equipped with a spraying mechanism 32. The methanol input pipeline 31 is connected to the spraying mechanism 32. By giving the DMT crystals with unsatisfactory color and purity Spraying fresh methanol liquid on the MT crystals can achieve the dilution and cleaning effect on the DMT crystals. During the dilution and cleaning process, impurities on the DMT crystals will be taken out, and the color quality and purity of the DMT crystals will be significantly improved. In the present invention, the structures of the three separation and decolorization units 100 are the same and are connected in series. The centrifuge 1 of the first separation and decolorization unit 100 receives the initial input DMT crude material. The present invention connects the DMT dilution tank 3 outlet pipeline of the previous separation and decolorization unit 100 to the material input port 11 of the centrifuge 1 of the next separation and decolorization unit 100. In this way, the DMT crude material forms an operation mode of separation, cleaning, re-separation, re-cleaning, third separation, and final dilution within the present invention. Each separation Cleaning will remove a large amount of impurities. After the continuous operation of the three separation and decolorization units 100, the hue quality and purity of the obtained DMT product can be greatly improved. The outlet of the DMT dilution tank 3 is located at the bottom of the DMT dilution tank 3. The hue quality and purity of the DMT in the DMT dilution tank 3 of the last separation and decolorization unit 100 have met the requirements. Therefore, the outlet pipeline of the DMT dilution tank 3 is connected to the molten storage unit 200, and the DMT after three decolorization and purification is transported to the molten storage unit 200 for storage. The volatile gas in the operation of the centrifuge 1 is mainly methanol. The gas phase outlet 14 of the centrifuge 1 is connected to the condensation treatment device 4 pipeline. The condensation treatment device 4 is provided with a reflux pipeline 42. Since the volatile methanol gas also carries impurities,Therefore, the condensed methanol liquid is not clean and has the same properties as the methanol separated liquid output from the liquid phase outlet 12. In the present invention, the reflux line 42 is connected in parallel to the liquid phase outlet 12 of the centrifuge 1 to mix with the separated liquid and discharge it.

[0031] Both the liquid phase separation liquid and the gas phase condensate contain impurities. The accumulation of impurities will cause pipe blockage and affect the stable operation of the regeneration DMT separation and decolorization system. Therefore, reducing pipe blockage problems and promptly eliminating pipe blockage failures have become the design focus of the regeneration DMT separation and decolorization system, which is related to the stable and efficient operation of the system.

[0032] like Figure 3 and Figure 4As shown, the liquid phase outlet 12 of the centrifuge 1 is in an inverted cone shape, and the liquid phase outlet 12 is installed with the cone tip facing down. The separated liquid output pipeline 2 includes a discharge pipe 21 and a first liquid outlet pump 22. The first liquid outlet pump 22 is responsible for pumping the separated liquid. The upper end of the discharge pipe 21 is vertically inserted into the liquid phase outlet 12, and the lower end of the discharge pipe 21 is connected to the inlet of the first liquid outlet pump 22. The discharge pipe 21 is used to drain the separated liquid output of the liquid phase outlet 12. The present invention designs the discharge pipe 21 to be inserted deeper, so that the top opening of the discharge pipe 21 forms a height difference with the bottom of the cone tip of the liquid phase outlet 12. Under this design, the top opening of the discharge pipe 21 The impurity precipitation effect is formed in the area below the opening. During the separation operation, the liquid level of the separated liquid gradually rises, and some impurities are precipitated below the opening of the discharge pipe 21. In this way, the impurity content of the separated liquid discharged from the discharge pipe 21 can be reduced. The purpose of this design is to reduce the probability of blockage failure of the separated liquid output pipeline 2. After the separation liquid output pipeline 2 is blocked, if it is not discovered in time, the separated liquid will have the risk of going to the solid phase outlet 13, which will contaminate the DMT dilution tank 3 and cause a production accident. Therefore, it is also very important to detect the blockage failure of the separation liquid output pipeline 2 in time. For this reason, the present invention is fixedly installed with a first partition in the liquid phase outlet 12. 121, a first liquid level detection chamber 122 is formed in the liquid phase outlet 12 by the first partition 121, and a first liquid level gauge 123 is installed in the first liquid level detection chamber 122. The first liquid level gauge 123 adopts a float type liquid level gauge. The first liquid level detection chamber 122 is connected to the inner cavity of the liquid phase outlet 12 at the lower end (the first partition 121 is not closed at the bottom). In this way, the liquid in the first liquid level detection chamber 122 overflows from the inner cavity of the liquid phase outlet 12. The liquid level of the first liquid level detection chamber 122 is the inner cavity liquid level of the liquid phase outlet 12. The present invention sets the control liquid level of the first liquid level gauge 123 to be higher than the liquid level of the discharge pipe 21. The top is open but lower than the highest point of the liquid phase outlet 12, which means that normal drainage will not trigger the first liquid level gauge 123. After the separation liquid output pipeline 2 is blocked, the inner cavity liquid level of the liquid phase outlet 12 will increase significantly until the first liquid level gauge 123 is triggered to form a pipe blockage alarm. The first partition 121 can also form an anti-disturbance interference function in the liquid phase outlet 12. When a large amount of separation liquid enters the liquid phase outlet 12, waves will be generated. The first partition 121 blocks the liquid waves and forms a stable liquid surface in the first liquid level detection cavity 122 to ensure that the first liquid level gauge 123 will not be triggered by mistake. Troubleshooting is required after the pipe blockage alarm, such as Figure 2As shown, the present invention is provided with a first valve 23 and a first backflush line 24 on the connecting pipeline between the discharge pipe 21 and the first liquid outlet pump 22. The first valve 23 is installed near the inlet of the first liquid outlet pump 22. When the first valve 23 is opened, the separation liquid output pipeline 2 is in a non-cut-off state. The first backflush line 24 and the first valve 23 are interlocked to control opening and closing. The interlocking rule is that the first backflush line 24 and the first valve 23 are not opened at the same time. The closing of the first valve 23 can cut off the separation liquid output pipeline 2, and then the first backflush line 24 can be opened to introduce 6 kg pressure of nitrogen into the separation liquid output pipeline 2 for backflush cleaning. Generally, the first valve 23 and the first backflush line 24 are alternately opened and closed 3-4 times to meet the pipe cleaning requirements. After the separation liquid output pipeline 2 is dredged, the liquid level in the liquid phase outlet 12 drops, and the pipe blocking alarm is lifted. If the pipe blocking alarm is not lifted, the liquid phase outlet 12 needs to be disassembled for cleaning.

[0033] like Figure 5 As shown, the condensation treatment device 4 includes a condenser 41, which is provided with a gas phase inlet 411 and a first condensate outlet 412. The gas phase outlet 14 of the centrifuge 1 is connected to the gas phase inlet 411 of the condenser 41 through a pipeline. The volatile gas of the centrifuge 1 is input into the condenser 41 through the pipeline for condensation. One end of the reflux line 42 is connected to the first condensate outlet 412 of the condenser 41, and the other end of the reflux line 42 is connected to the liquid phase outlet 12 of the centrifuge 1. The reflux line 42 serves as a reflux of the condensate. Since the reflux line 42 is also connected to the centrifuge 1, it is possible that the volatile gas of the centrifuge 1 is directly input into the first condensate outlet 412 of the condenser 41 from the reflux line 42. If the volatile gas enters from the first condensate outlet 412, the volatile gas will not be condensed, and the exhaust gas from the gas phase outlet of the condenser 41 is the untreated volatile gas. The U-bend 421 can prevent the volatile gas from being output through the reflux pipeline 42, but it will also cause the pipe to be blocked (the impurities in the condensate are easily precipitated when the U-bend 421 is opened). For this reason, the present invention also designs a backwash structure to solve the pipe blocking problem. Figure 5The arrow direction shown is the flow direction of the condensate in the U-shaped bend 421. According to the flow direction of the condensate in the U-shaped bend 421, an inlet end and an outlet end of the U-shaped bend 421 are provided. A second valve 423 is installed at the inlet end of the U-shaped bend 421. The outlet end of the U-shaped bend 421 is connected to the second backflush pipeline 424. A third valve 425 is installed on the connecting pipeline between the outlet end of the U-shaped bend 421 and the liquid phase outlet 12 of the centrifuge 1. The second backflush pipeline 424, the second valve 423 and the third valve 425 are opened and closed by interlocking control. The interlocking rule is that when the second backflush pipeline 424 is opened, one of the second valve 423 and the third valve 425 is opened. When the second valve 423 and the third valve 425 are opened at the same time, the second backflush pipeline 424 is opened. The pipeline 424 is closed, and the second backflush pipeline 424 is opened to provide 6 kg of nitrogen pressure into the pipeline. At this time, the second valve 423 and the third valve 425 are opened alternately. If the second valve 423 is opened in cooperation, the U-shaped bend 421 can be backwashed, and if the third valve 425 is opened in cooperation, the pipeline on the left side of the third valve 425 can be backwashed. The U-shaped bend 421 is most likely to be blocked, so the number of times the backflush U-shaped bend 421 is set should be relatively large. When backflushing the U-shaped bend 421, there is a risk of flushing pipe-blocking impurities into the interior of the condenser 41, which will cause damage to the condenser 41 and affect its use effect and service life. For this reason, the present invention connects the first condensate outlet 412 of the condenser 41 with the backflush auxiliary box 43 to solve the above problem. Figure 6As shown, the backwash auxiliary box 43 includes a box body 431, a second partition 434 and a third partition 437. The top of the box body 431 is connected to the first condensate outlet 412, that is, the backwash auxiliary box 43 is directly connected to the condenser 41. The box body 431 is provided with a second condensate outlet 432 at the bottom. The second condensate outlet 432 is staggered with the first condensate outlet 412. The inlet end pipeline of the U-shaped bend 421 is connected to the second condensate outlet 432. The condensate first enters the backwash auxiliary box 43 and then enters the U-shaped bend 421 through the second condensate outlet 432. The second condensate outlet 432 is installed with a filter 433 in the box body 431. The filter 433 can form a certain impurity filtering efficiency for the condensate to reduce the impurities entering the U-shaped bend 421. The probability of pipe blockage, of course, there will be a dirt layer on the mesh surface of the filter 433, and there will also be a risk of blockage. The second partition 434 is installed in the box body 431, and a second liquid level detection chamber 435 is formed in the box body 431 through the second partition 434. The bottom of the second liquid level detection chamber 435 is connected with the inner cavity of the box body 431. The liquid level in the second liquid level detection chamber 435 is the liquid level in the inner cavity of the box body 431. After the U-shaped bend 421 or the filter 433 is blocked, the liquid level in the inner cavity of the box body 431 rises, driving the liquid level in the second liquid level detection chamber 435 to rise. A second liquid level gauge 436 is installed in the second liquid level detection chamber 435. The second liquid level gauge 436 can detect pipe blockage faults by detecting the liquid level to send out an alarm signal. The function of the second partition 43 is similar to that of the first partition 121. , which has the effect of preventing turbulent flow interference. After the pipe blockage fault alarm signal is issued, the second backflush line 424 is controlled to perform backflush operation. During the backflush operation, dirt and impurities must be prevented from directly entering the condenser 41. Therefore, the present invention first staggers the second condensate outlet 432 and the first condensate outlet 412 to reduce the risk of impurities entering the condenser 41 through the first condensate outlet 412. The present invention also fixes a third partition 437 in the box 431. Only the bottom edge of the third partition 437 does not contact the inner wall of the box 431. That is to say, the existence of the third partition 437 does not affect the flow of condensate at the bottom of the box 431. The present invention also designs and fixes a diffuser cone 438 in the box 431. The diffuser cone 438 is installed with the cone tip facing downward. The diffuser cone 438 is arranged just above the second condensate outlet 432. When the pipeline is backflushed, impurities and dirt gush upward from the second condensate outlet 432. When encountering the diffuser cone 438, they can form an umbrella-shaped scattering effect to the surroundings. The third partition plate 437 is installed in conjunction with the diffuser cone 438. The third partition plate 437 is arranged on the side of the diffuser cone 438. The diffuser cone 438 is located between the third partition plate 437 and the inner wall of the box body 431. The umbrella-shaped scattering is blocked by the third partition plate 437 to form a natural fall. Due to the blocking effect of the third partition plate 437, the risk of impurities entering the condenser 41 through the first condensate outlet 412 is completely solved. In this way, the operation of the backflushing pipeline will not bring negative problems. The present invention is provided with cleaning ports 439 on the side and bottom of the backflushing auxiliary box 43.The cleaning port 439 is sealed and closed parallel to the box. It needs to be opened after each shift to clean the box.

[0034] like Figure 2 As shown, the centrifuge 1 is equipped with a cleaning pipeline 15. The cleaning pipeline 15 is designed with two parts: air replacement and methanol cleaning. The centrifuge 1 needs to be cleaned before and after work. First, fresh methanol liquid is introduced to spray and clean the drum components, and then 0.1 kg pressure nitrogen is introduced to replace the air in the equipment. The 0.1 kg pressure nitrogen needs to be continuously introduced during the operation of the centrifuge 1 to ensure the stability of the internal environment. Figure 6 As shown, the recoil auxiliary box 43 is also designed with an air replacement pipeline. Before the recoil auxiliary box 43 is opened, nitrogen with a pressure of 0.1 kg needs to be introduced to replace the air in the box.

[0035] A method for separating and decolorizing regenerated DMT is implemented using a system for separating and decolorizing regenerated DMT, comprising the following steps:

[0036] (a) The crude DMT produced by the transesterification reaction is conveyed to the first separation and decolorization unit 100 via a pipeline. The crude DMT is conveyed to the centrifuge 1 via a pipeline. After centrifugal separation, the liquid material is discharged from the separation liquid output pipeline 2 through the liquid phase outlet 12 to achieve initial impurity separation. The solid material is discharged to the DMT dilution tank 3 through the solid phase outlet 13. The solid material is cleaned and diluted in the DMT dilution tank 3 to form a primarily diluted DMT solution. The gaseous material is discharged to the condensation treatment device 4 through the gas phase outlet 14. The condensate is refluxed to the liquid phase outlet 12 through the reflux line 42 and then discharged from the separation liquid output pipeline 2.

[0037] (b) The diluted DMT solution in the DMT dilution tank 3 of the first separation and decolorization unit 100 is transported to the centrifuge 1 of the second separation and decolorization unit 100 through a series pipeline, and step a is repeated to form a further diluted DMT solution in the DMT dilution tank 3 of the second separation and decolorization unit 100;

[0038] (c) The diluted DMT solution in the DMT dilution tank 3 of the second separation and decolorization unit 100 is transported to the centrifuge 1 of the third separation and decolorization unit 100 through the series pipeline, and step a is repeated to form a third diluted DMT solution in the DMT dilution tank 3 of the third separation and decolorization unit 100;

[0039] (d) The diluted DMT solution in the DMT dilution tank 3 of the second separation and decolorization unit 100 is transported to the molten storage unit 200 via a series pipeline. The DMT solution is first heated in the heater 201 to form a molten DMT. The molten DMT solution is then transported to the heat-insulating storage tank 202 for heat preservation and storage.

[0040] After the three-stage decolorization and purification of the present invention, the crude DMT material can be transformed into a DMT product with good hue quality (changing from black to light gray, where the color change indicates fewer impurities and higher purity). The separation and decolorization system of the present invention is designed with a series of fault handling mechanisms to ensure stable and efficient operation.

[0041] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A separation and decolorization system for regenerating DMT, characterized in that: The invention comprises a plurality of separation and decolorization units (100) and a melt storage unit (200), wherein the plurality of separation and decolorization units (100) are sequentially connected in series through pipelines, and the melt storage unit (200) is connected in series to the rear of the last separation and decolorization unit (100). The separation and decolorization unit (100) comprises a centrifuge (1), a DMT dilution tank (3) and a condensation treatment device (4), wherein the centrifuge (1) is provided with a material input port (11), a liquid phase outlet (12), a solid phase outlet (13) and a gas phase outlet (14), wherein the liquid phase outlet (12) is connected to a separation liquid output pipeline (2), and the solid phase outlet (13) is connected to a gas phase outlet (14). The phase outlet (13) is connected to the DMT dilution tank (3) pipeline, the gas phase outlet (14) is connected to the condensation treatment device (4) pipeline, the condensation treatment device (4) is provided with a reflux pipeline (42), the reflux pipeline (42) is connected to the liquid phase outlet (12) of the centrifuge (1), the DMT dilution tank (3) outlet pipeline of the previous separation and decolorization unit (100) is connected to the material input port (11) of the centrifuge (1) of the next separation and decolorization unit (100), and the DMT dilution tank (3) outlet pipeline of the last separation and decolorization unit (100) is connected to the melt storage unit (200).

2. A separation and decolorization system for regenerating DMT according to claim 1, characterized in that: The number of separation and decolorization units (100) is three. The liquid phase outlet (12) of the centrifuge (1) is in an inverted cone shape. The separated liquid output pipeline (2) comprises a discharge pipe (21) and a first liquid outlet pump (22). The upper end of the discharge pipe (21) is vertically inserted into the liquid phase outlet (12). The lower end of the discharge pipe (21) is connected to the inlet of the first liquid outlet pump (22). The top of the discharge pipe (21) is open and forms a height difference with the bottom of the cone tip of the liquid phase outlet (12). The centrifuge (1) is equipped with a cleaning pipeline (15).

3. A separation and decolorization system for regenerating DMT according to claim 1, characterized in that: A first partition (121) is fixedly installed in the liquid phase outlet (12), and a first liquid level detection cavity 122 is formed by dividing the liquid phase outlet (12) through the first partition (121). A first liquid level gauge (123) is installed in the first liquid level detection cavity 122. The first liquid level gauge (123) is a float type liquid level gauge. The first liquid level detection cavity 122 is connected to the inner cavity of the liquid phase outlet (12) at the lower end.

4. A separation and decolorization system for regenerating DMT according to claim 2, characterized in that: A first valve (23) and a first backflushing pipeline (24) are installed on the connecting pipeline between the discharge pipe (21) and the first liquid discharge pump (22). The first valve (23) is installed close to the inlet of the first liquid discharge pump (22). The first backflushing pipeline (24) and the first valve (23) are opened and closed by interlocking control.

5. A separation and decolorization system for regenerating DMT according to claim 1, characterized in that: A methanol input pipeline (31) is connected to the side of the DMT dilution tank (3), a spray mechanism (32) is installed in the DMT dilution tank (3), the methanol input pipeline (31) is connected to the spray mechanism (32), and the outlet of the DMT dilution tank (3) is arranged at the bottom of the DMT dilution tank (3).

6. A separation and decolorization system for regenerating DMT according to claim 1, characterized in that: The condensation treatment device (4) comprises a condenser (41), the condenser (41) being provided with a gas phase inlet (411) and a first condensate outlet (412), the gas phase outlet (14) pipeline of the centrifuge (1) being connected to the gas phase inlet (411) of the condenser (41), one end of the reflux line (42) being connected to the first condensate outlet (412) of the condenser (41), and the other end of the reflux line (42) being connected to the liquid phase outlet (12) of the centrifuge (1).

7. A separation and decolorization system for regenerating DMT according to claim 6, characterized in that: The reflux pipeline (42) is provided with a U-shaped bend (421), and the U-shaped bend (421) is provided with a replenishing liquid pipeline (422). The inlet end and the outlet end of the U-shaped bend (421) are provided according to the flow direction of the condensate in the U-shaped bend (421). A second valve (423) is installed at the inlet end of the U-shaped bend (421), and a second backwash pipeline (424) is connected to the outlet end of the U-shaped bend (421). A third valve (425) is installed on the connecting pipeline between the outlet end of the U-shaped bend (421) and the liquid phase outlet (12) of the centrifugal separator (1). The second backwash pipeline (424), the second valve (423) and the third valve (425) are opened and closed by interlocking control.

8. A separation and decolorization system for regenerating DMT according to claim 6, characterized in that: The first condensate outlet (412) of the condenser (41) is connected to a backwash auxiliary box (43), and the backwash auxiliary box (43) comprises a box body (431), a second partition (434), and a third partition (437). The top of the box body (431) is connected to the first condensate outlet (412). The box body (431) is provided with a second condensate outlet (432), and the second condensate outlet (432) is staggered with the first condensate outlet (412). The inlet end pipeline of the U-shaped bend (421) is connected to the second condensate outlet (432). The second condensate outlet (432) is provided with a filter (433) in the box body (431). The second partition (434) is installed in the box body (431). ) A second liquid level detection chamber (435) is formed in the box body (431), the bottom of the second liquid level detection chamber (435) is communicated with the inner chamber of the box body (431), a second liquid level gauge (436) is installed in the second liquid level detection chamber (435), the third partition (437) is fixedly installed in the box body (431), only the bottom edge of the third partition (437) does not contact the inner wall of the box body (431), a diffuser cone (438) is fixedly installed in the box body (431), the diffuser cone (438) is installed with the cone tip facing downward, the diffuser cone (438) is arranged directly above the second condensate outlet (432), the third partition (437) is arranged on the side of the diffuser cone (438), and the backflushing auxiliary box (43) is provided with a cleaning port (439) on both the side and bottom surfaces.

9. A separation and decolorization system for regenerating DMT according to claim 1, characterized in that: The molten storage unit (200) comprises a heater (201) and a heat preservation storage tank (202) connected in series, wherein the inlet pipeline of the heater (201) is connected to the outlet of the DMT dilution tank (3), and the outlet of the heater (201) is connected to the pipeline of the heat preservation storage tank (202).

10. A method for separating and decolorizing regenerated DMT, which is achieved by using a system for separating and decolorizing regenerated DMT according to any one of claims 1 to 9, characterized in that: The steps include: (a) The crude DMT produced by the transesterification reaction is transported to the first separation and decolorization unit (100) through a pipeline. The crude DMT is transported to the centrifuge (1) through a pipeline. After centrifugal separation, the liquid substance is output from the separation liquid output pipeline (2) through the liquid phase outlet (12). The solid substance is output to the DMT dilution tank (3) through the solid phase outlet (13). The solid substance is washed and diluted in the DMT dilution tank (3) to form a first diluted DMT solution. The gaseous substance is output to the condensation treatment device (4) through the gas phase outlet (14). The condensate is refluxed to the liquid phase outlet (12) through the reflux pipeline (42) and then converged and output from the separation liquid output pipeline (2). (b) The diluted DMT solution in the DMT dilution tank (3) of the first separation and decolorization unit (100) is transported to the centrifuge (1) of the second separation and decolorization unit (100) through a series pipeline, and step (a) is repeated to form a further diluted DMT solution in the DMT dilution tank (3) of the second separation and decolorization unit (100); (c) The diluted DMT solution in the DMT dilution tank (3) of the second separation and decolorization unit (100) is transported to the centrifuge (1) of the third separation and decolorization unit (100) through a series pipeline, and step (a) is repeated to form a third diluted DMT solution in the DMT dilution tank (3) of the third separation and decolorization unit (100); (d) The diluted DMT solution in the DMT dilution tank (3) of the second separation and decolorization unit (100) is transported to the molten storage unit (200) through a series pipeline. The DMT solution is first heated by a heater (201) to form a molten state. The molten DMT solution is then transported to the heat preservation storage tank (202) for heat preservation and storage.

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