A separation and decoloring system for regenerating DMT and a separation and decoloring method thereof

Abstract

The application discloses a kind of separation decoloring systems of regenerating DMT, including several separation decoloring units and a molten storage unit, several separation decoloring units are sequentially piped in series, molten storage unit piped in series is in the last separation decoloring unit after track, separation decoloring unit includes centrifugal separator, DMT dilution tank and condensation treatment device, centrifugal separator is equipped with material input, liquid phase outlet, solid phase outlet and gas phase outlet, liquid phase outlet is connected with separation liquid output pipeline, solid phase outlet is connected with DMT dilution tank pipeline, gas phase outlet is connected with condensation treatment device pipeline, condensation treatment device is equipped with reflux pipeline, reflux pipeline connects the liquid phase outlet of centrifugal separator, the application is designed with three-stage separation decoloring unit in series, and the decoloring purification effect of DMT crude material product is realized by three times separation dilution operation, the application can effectively solve the pipeline blockage fault problem in system operation, ensure that system can be stably, continuously and efficiently operated.

Description

TECHNICAL FIELD

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

[0002] The chemical method is used to circularly produce regenerated DMT (dimethyl terephthalate), which is a technical means for recycling and regenerating waste textiles (polyester fiber material accounts for more than 90%) as raw materials. The chemical method circularly produces regenerated DMT, which needs to go through a system process of textile sorting, crushing, depolymerization, concentration, and ester exchange. After the ester exchange process, crude material containing DMT components can be obtained. However, due to the complex source of waste textiles, there are many impurity components such as dyes and oil agents in the DMT crude material. The existence of impurities makes the color of the DMT crude material product unsatisfactory. Moreover, due to the low purity of DMT, it cannot be directly used for development and utilization. Therefore, the decolorization and purification operation of the DMT crude material is a necessary step for the industrialization application of regenerated DMT. The use of centrifugal equipment for decolorization and purification of DMT crude material product is the existing way. How to layout the centrifugal equipment to obtain better decolorization and purification quality is the difficulty of technical research. Moreover, a large amount of separated impurities will be produced in the centrifugal operation. The accumulation of these separated impurities in the system pipeline will cause pipe blockage failure, which will lead to production stagnation and affect product quality. Therefore, in the technical improvement of the existing centrifugal equipment system, the timely discovery and timely removal of pipe blockage failure are also the focus and difficulty of research. Enterprises need to improve the design of a stable and efficient separation and decolorization equipment system for regenerated DMT to meet the production. SUMMARY

[0003] The present application aims to solve the above-mentioned needs of the prior art, and provides a separation and decolorization system for regenerated DMT and a separation and decolorization method thereof. The present application is designed with three-stage separation and decolorization units in series, which realizes the decolorization and purification effect of DMT crude material product through three separation and dilution operations. The present application is designed with an anti-blocking structure on the key equipment, which can timely discover and effectively solve the pipe blockage failure problem in the system operation, and ensure the stable and continuous efficient operation of the regenerated DMT separation and decolorization system.

[0004] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0005] The application discloses a separation and decoloring system for regenerating DMT, which comprises a plurality of separation and decoloring units and a molten storage unit, the separation and decoloring units are connected in series, the molten storage unit is connected behind the last separation and decoloring unit, the separation and decoloring 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 separation liquid output pipeline, the solid phase outlet is connected with the DMT dilution tank, the gas phase outlet is connected with the condensation treatment device, the condensation treatment device is provided with a reflux pipeline, one end of the reflux pipeline is connected with the liquid phase outlet of the centrifugal separator, the DMT dilution tank of the previous separation and decoloring unit is connected with the material input port of the centrifugal separator of the next separation and decoloring unit, and the DMT dilution tank of the last separation and decoloring unit is connected with the molten storage unit.

[0006] Further, the separation and decoloring unit is provided in three, the liquid phase outlet of the centrifugal separator is inverted conical, the separation liquid output pipeline comprises a liquid discharge pipe and a first liquid outlet pump, the upper end of the liquid discharge pipe is vertically inserted into the liquid phase outlet, the lower end of the liquid discharge pipe is connected with the inlet of the first liquid outlet pump, the top of the liquid discharge pipe is open and is connected with the bottom of the inverted conical liquid phase outlet, and the centrifugal separator is provided with a cleaning pipeline.

[0007] Further, the liquid phase outlet is fixedly provided with a first partition plate, a first liquid level detection cavity is formed in the liquid phase outlet through the first partition plate, a first liquid level meter is arranged in the first liquid level detection cavity, the first liquid level meter is a float ball type liquid level meter, and the first liquid level detection cavity is connected with the inner cavity of the liquid phase outlet at the lower end.

[0008] Further, the first valve and a first backflush pipeline are arranged on the connecting pipeline between the liquid discharge pipe and the first liquid outlet pump, the first valve is arranged close to the inlet of the first liquid outlet pump, and the first backflush pipeline is connected with the first valve and is controlled to be opened and closed in interlocking mode.

[0009] Further, a methanol input pipeline is arranged on the side of the DMT dilution tank, a spraying mechanism is arranged in the DMT dilution tank, the methanol input pipeline is connected with the spraying mechanism, and the outlet of the DMT dilution tank is arranged at the bottom of the DMT dilution tank.

[0010] Further, the condensation treatment device comprises a condenser, the condenser is provided with a gas phase inlet and a first condensate outlet, the gas phase outlet of the centrifugal separator is connected with the gas phase inlet of the condenser, one end of the reflux pipeline is connected with the first condensate outlet of the condenser, and the other end of the reflux pipeline is connected with the liquid phase outlet of the centrifugal separator.

[0011] Further, the reflux pipeline is provided with a U-shaped bend, the U-shaped bend is provided with a supplementary liquid pipeline, 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, a second backflushing 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 centrifugal separator, and the second backflushing pipeline, the second valve and the third valve are opened and closed through interlocking control.

[0012] Further, the first condensate outlet of the condenser is connected to install a backflushing auxiliary tank, the backflushing auxiliary tank comprises a tank body, a second partition plate and a third partition plate, the top of the tank body is connected in communication with the first condensate outlet, the tank body is provided with a second condensate outlet, the second condensate outlet is arranged in a staggered manner with the first condensate outlet, the inlet end pipeline of the U-shaped bend is connected to the second condensate outlet, a filter is installed in the second condensate outlet in the tank body, the second partition plate is installed in the tank body, a second liquid level detection cavity is formed in the tank body through the second partition plate, the bottom of the second liquid level detection cavity is connected in communication with the inner cavity of the tank body, a second liquid level meter is installed in the second liquid level detection cavity, the third partition plate is fixedly installed in the tank body, only the bottom edge of the third partition plate does not contact the inner wall of the tank body, a flow dispersing cone is fixedly installed in the tank body, the flow dispersing cone is installed with the cone tip downward, the flow dispersing cone is arranged directly above the second condensate outlet, the third partition plate is arranged at the side of the flow dispersing cone, and the backflushing auxiliary tank is provided with cleaning openings on the side surface and the bottom surface.

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

[0014] A separation and decolorization method of regenerated DMT is realized by using a separation and decolorization system of regenerated DMT, comprising the following steps:

[0015] (a) The DMT crude material produced by the ester exchange reaction is transported to the first separation and decolorization unit through a pipeline, the DMT crude material is transported into a centrifugal separator through a pipeline, after the centrifugal separation operation, the liquid material is output from the separation liquid output pipeline through the liquid phase outlet, the solid material is output to the DMT dilution tank through the solid phase outlet, the solid material completes the cleaning and dilution operation in the DMT dilution tank to form the first diluted DMT solution, the gaseous material is output to the condensation treatment device through the gas phase outlet, and the condensate is returned to the liquid phase outlet through the reflux pipeline and is output from the separation liquid output pipeline in a converged manner;

[0016] (b) the DMT solution diluted in the DMT dilution tank of the first separation and decolorization unit is transported to the centrifugal separator of the second separation and decolorization unit through the serial pipeline, the step (a) is repeated, and the DMT solution diluted again is formed in the DMT dilution tank of the second separation and decolorization unit;

[0017] (c) the DMT solution diluted in the DMT dilution tank of the second separation and decolorization unit is transported to the centrifugal separator of the third separation and decolorization unit through the serial pipeline, the step (a) is repeated, and the DMT solution diluted for the third time is formed in the DMT dilution tank of the third separation and decolorization unit;

[0018] (d) the DMT solution diluted in the DMT dilution tank of the second separation and decolorization unit is transported to the melting storage unit through the serial pipeline, the DMT solution is heated by the heater first, the DMT is formed into the molten state, and then the molten DMT solution is transported to the heat preservation storage tank for heat preservation storage.

[0019] The beneficial effects of the present application are as follows:

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

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

[0022] Figure 1 It is a whole structure principle diagram of a regenerated DMT separation and decolorization system in the embodiment;

[0023] Figure 2 It is a structure principle diagram of a separation and decolorization unit in the embodiment;

[0024] Figure 3 It is an internal structure front view of a liquid phase outlet of a centrifugal separator in the embodiment;

[0025] Figure 4 It is an internal structure side view of a liquid phase outlet of a centrifugal separator in the embodiment;

[0026] Figure 5 It is a structure principle diagram of a condensation treatment device in the embodiment;

[0027] Figure 6 It is an internal structure diagram of a backflushing auxiliary tank in the embodiment.

[0028] Separation and decolorization unit 100, melting storage unit 200, heater 201, heat preservation storage tank 202, centrifugal separator 1, material input port 11, liquid phase outlet 12, first partition plate 121, first liquid level detection cavity 122, first liquid level meter 123, solid phase outlet 13, gas phase outlet 14, cleaning pipeline 15, separation liquid output pipeline 2, liquid discharge pipeline 21, first liquid outlet pump 22, first valve 23, first backflush pipeline 24, DMT dilution tank 3, methanol input pipeline 31, spraying mechanism 32, condensation treatment device 4, condenser 41, gas phase inlet 411, first condensate outlet 412, reflux pipeline 42, U-shaped bend 421, supplementary liquid pipeline 422, second valve 423, second backflush pipeline 424, third valve 425, backflush auxiliary tank 43, tank body 431, second condensate outlet 432, filter 433, second partition plate 434, second liquid level detection cavity 435, second liquid level meter 436, third partition plate 437, flow dispersing cone 438, cleaning port 439. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0030] As Figures 1-6The illustrated regenerated DMT separation decolorization system includes a plurality of separation decolorization units 100 and a molten storage unit 200. The plurality of separation decolorization units 100 are sequentially connected in series by pipelines. The separation decolorization unit 100 realizes decolorization and purification of the DMT crude material through solid-liquid separation operation. The main components of the DMT crude material are methanol liquid, DMT crystalline and impurities. Most of the impurities are dissolved in the methanol liquid. Through the solid-liquid separation operation of the methanol liquid and the DMT crystalline, a large amount of impurities can be removed (the impurities are removed by the methanol liquid). After a large amount of impurities are removed, the remaining DMT product has greatly improved color quality and purity. In order to ensure the decolorization and purification effect and control the production cost, the actual number of separation decolorization units 100 is three. The three separation decolorization units 100 are sequentially connected in series. After the DMT crude material continuously undergoes three repeated separation decolorization operations, the color quality and purity of the DMT crude material meet the production design requirements (the DMT crude material product is black, and after the DMT product obtained after the three separation decolorization units 100 is light gray, which represents that the decolorization and purification is obvious and can meet the needs of subsequent rectification work). The molten storage unit 200 is connected in series after the last separation decolorization unit 100. The molten storage unit 200 includes a heater 201 and a heat preservation storage tank 202 connected in series. The inlet pipeline of the heater 201 is connected to the last separation decolorization unit 100. The outlet of the heater 201 is connected to the pipeline of the heat preservation storage tank 202. The DMT product after three decolorization and purification operations is first input into the heater 201 for heating, so that the DMT crystalline is heated to become a molten state. The molten DMT is dissolved in fresh methanol to form a solution, which is then output to the heat preservation storage tank 202 for storage. The heat preservation storage tank 202 is provided with a heat preservation layer to ensure that the DMT remains in a molten state. The heat preservation storage tank 202 is connected to a rectification work device. The DMT product can be output to the rectification work device for further processing as needed, such as Figure 2As shown, in the present application, the separation and decolorization unit 100 comprises a centrifugal separator 1, a DMT dilution tank 3 and a condensation treatment device 4, the centrifugal separator 1 used in the present application is a drum-type centrifugal separation device purchased on the market, which is a prior art, and the structural principle is not introduced much, the centrifugal separator 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 centrifugal separator 1 from the material input port 11, under the condition that the drum rotates at a high speed, the liquid is thrown out from the drum and is collected to the liquid phase outlet 12 for output, and the separated solid is pushed to the solid phase outlet 13 for output by the screw conveying mechanism, and volatile gas is also generated in the centrifugal separation process, and the gas is output from the gas phase outlet 14, the main component of the liquid separated by the centrifugal separator is methanol, and the liquid is also mixed with impurities, so the liquid phase outlet 12 is connected with a separated liquid output pipeline 2, and the separated methanol liquid is output through the separated liquid output pipeline 2, the solid separated by the centrifugal separator is DMT crystal, and the color and purity of the DMT crystal are not ideal, so the solid phase outlet 13 is connected with the DMT dilution tank 3 pipeline, and the DMT crystal is directly discharged into the DMT dilution tank 3, a methanol input pipeline 31 is connected and installed on the side of the DMT dilution tank 3, the methanol input pipeline 31 can supplement fresh high-purity methanol liquid to the DMT dilution tank 3, a spraying mechanism 32 is installed in the DMT dilution tank 3, the methanol input pipeline 31 is communicated with the spraying mechanism 32, and the spraying of fresh methanol liquid on the DMT crystal with non-ideal color and purity can achieve the dilution and cleaning effect of the DMT crystal, in the dilution and cleaning process, the impurities on the DMT crystal are taken out, and the color and purity of the DMT crystal are significantly improved, in the present application, the structures of the three separation and decolorization units 100 are the same, and are sequentially connected in series, the centrifugal separator 1 of the first separation and decolorization unit 100 receives the initially input DMT crude material, the outlet pipeline of the DMT dilution tank 3 of the previous separation and decolorization unit 100 is connected to the material input port 11 of the centrifugal separator 1 of the subsequent separation and decolorization unit 100, so that the DMT crude material forms a separation, cleaning, re-separation, re-cleaning, third separation and final dilution operation mode in the present application, a large amount of impurities are removed each time, and the color and purity of the DMT product obtained through the continuous operation of the three separation and decolorization units 100 can be greatly improved, the outlet of the DMT dilution tank 3 is arranged at the bottom of the DMT dilution tank 3, the DMT in the DMT dilution tank 3 of the last separation and decolorization unit 100 has color and purity meeting the requirements, so the outlet pipeline of the DMT dilution tank 3 is connected to a melting storage unit 200, and the DMT after three times of decolorization and purification is transported to the melting storage unit 200 for storage, the volatile gas in the operation of the centrifugal separator 1 is mainly composed of methanol, the gas phase outlet 14 of the centrifugal separator 1 is connected with a condensation treatment device 4 pipeline, and 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 property as the methanol separation liquid output from the liquid phase outlet 12. The present application connects the reflux pipeline 42 to the liquid phase outlet 12 of the centrifugal separator 1 in parallel, and discharges the mixture with the separation liquid.

[0031] No matter the liquid phase separation liquid or the gas phase condensed liquid, the impurities contained therein will cause pipe blockage failure and affect the stable operation of the regenerated DMT separation and decoloring system. Therefore, reducing the pipe blockage problem and timely eliminating the pipe blockage failure become the design focus of the regenerated DMT separation and decoloring system, which is related to the stable and efficient operation of the system.

[0032] As Figure 3 and Figure 4As shown, the liquid phase outlet 12 of the centrifugal separator 1 is inverted conical, the liquid phase outlet 12 is installed with the cone tip downward, the separated liquid output pipeline 2 comprises a liquid discharge pipe 21 and a first liquid outlet pump 22, the first liquid outlet pump 22 is responsible for pumping the separated liquid output, the upper end of the liquid discharge pipe 21 is vertically inserted into the liquid phase outlet 12, the lower end of the liquid discharge pipe 21 is connected to the inlet of the first liquid outlet pump 22, and the liquid discharge pipe 21 is used to guide the separated liquid output of the liquid phase outlet 12, the liquid discharge pipe 21 is designed to be inserted deep, so that the top opening of the liquid discharge pipe 21 forms a height difference with the bottom of the cone tip of the liquid phase outlet 12, under this design, the area below the top opening of the liquid discharge pipe 21 forms a sedimentation effect of impurities, during the separation operation, the liquid level of the separated liquid gradually rises, and part of the impurities are deposited below the opening of the liquid discharge pipe 21, so that the impurity content of the separated liquid discharged into the liquid discharge pipe 21 can be reduced, the purpose of this design is to reduce the probability of pipe blockage failure of the separated liquid output pipeline 2, after the separated liquid output pipeline 2 is blocked, if it is not discovered in time, there is a risk that the separated liquid will flow out of the solid phase outlet 13, which will pollute the DMT dilution tank 3 and cause production accidents, therefore, it is also very important to discover the pipe blockage failure of the separated liquid output pipeline 2 in time, for this purpose, the first baffle 121 is fixedly installed in the liquid phase outlet 12, the first baffle 121 divides the liquid phase outlet 12 to form a first liquid level detection cavity 122, the first liquid level detection cavity 122 is installed with a first liquid level meter 123, the first liquid level meter 123 is a float ball type liquid level meter, the first liquid level detection cavity 122 is connected with the inner cavity of the liquid phase outlet 12 at the lower end (the first baffle 121 does not fall to the bottom to be closed), so that the liquid in the first liquid level detection cavity 122 is overflowed from the inner cavity of the liquid phase outlet 12, the liquid level of the first liquid level detection cavity 122 is the liquid level of the inner cavity of the liquid phase outlet 12, the control liquid level of the first liquid level meter 123 is set to be higher than the top opening of the liquid discharge pipe 21 but lower than the highest point of the liquid phase outlet 12, that is to say, normal liquid discharge will not trigger the first liquid level meter 123, after the separated liquid output pipeline 2 is blocked, the liquid level of the inner cavity of the liquid phase outlet 12 will be significantly increased until the first liquid level meter 123 is triggered to form a pipe blockage alarm, the first baffle 121 can also form an anti-turbulence interference effect in the liquid phase outlet 12, when a large amount of separated liquid enters the liquid phase outlet 12, wave conditions will be generated, the first baffle 121 blocks the liquid wave to form a stable liquid surface in the first liquid level detection cavity 122, so as to ensure that the first liquid level meter 123 will not be triggered by mistake, after the pipe blockage alarm, troubleshooting needs to be carried out, such as Figure 2As shown, the present invention has a first valve 23 and a first backflushing line 24 installed on the connecting pipeline between the drain pipe 21 and the first outlet pump 22. The first valve 23 is installed near the inlet of the first outlet pump 22. When the first valve 23 is open, the separated liquid output pipeline 2 is in a non-cut-off state. The first backflushing line 24 and the first valve 23 are interlocked to control their opening and closing. The interlocking rule is that the first backflushing line 24 and the first valve 23 cannot be opened at the same time. Closing the first valve 23 can cut off the separated liquid output pipeline 2. Then, opening the first backflushing line 24 can introduce nitrogen gas at a pressure of 6 kg to the separated liquid output pipeline 2 for backflushing and cleaning. Generally, the first valve 23 and the first backflushing line 24 are alternately opened and closed 3-4 times to meet the pipeline clearing requirements. After the separated liquid output pipeline 2 is cleared, the liquid level in the liquid outlet 12 drops and the blockage alarm is released. If the blockage alarm is not released, the liquid outlet 12 needs to be disassembled for cleaning.

[0033] like Figure 5 As shown, the condensation treatment device 4 includes a condenser 41, which has 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. The volatile gas from the centrifuge 1 is input into the condenser 41 for condensation. One end of the return line 42 is connected to the first condensate outlet 412 of the condenser 41, and the other end is connected to the liquid phase outlet 12 of the centrifuge 1. The return line 42 serves as a return flow for the condensate. Since the return line 42 is also connected to the centrifuge 1, the volatile gas from the centrifuge 1 may be directly input into the first condensate outlet 412 of the condenser 41 from the return line 42. If the volatile gas enters from the first condensate outlet 412, it will not be condensed, and the exhaust gas from the gas phase outlet of the condenser 41 will be the untreated volatile gas. This would cause the condenser 41 to fail, and allowing volatile gas to flow through the return line 42 is unacceptable. Therefore, this invention includes a U-bend 421 on the return line 42, with a replenishing liquid line 422 on the U-bend 421. The replenishing liquid line 422 replenishes the U-bend 421 with fresh methanol liquid. The presence of liquid in the U-bend 421 creates a liquid seal, preventing volatile gas from flowing through the return line 42. The U-bend 421 only needs replenishment during the initial startup phase, as the lack of condensate formation during startup prevents the liquid seal from forming. After the condenser 41 is operating normally, the continuous inflow of condensate into the U-bend 421 eliminates the need to open the replenishing liquid line 422. While the U-bend 421 prevents volatile gas from flowing through the return line 42, it can also cause blockage (the U-bend 421 is prone to precipitating impurities in the condensate). Therefore, this invention also incorporates a backflushing structure to address this blockage issue. Figure 5The arrow direction shown is the flow direction of the condensed liquid in the U-shaped bend 421, the inlet end and the outlet end of the U-shaped bend 421 are arranged according to the flow direction of the condensed liquid in the U-shaped bend 421, the second valve 423 is installed at the inlet end of the U-shaped bend 421, the second backflushing pipeline 424 is connected at the outlet end of the U-shaped bend 421, the 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 backflushing 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 backflushing 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 backflushing pipeline 424 is closed, the second backflushing pipeline 424 is opened to provide a nitrogen gas inlet pipeline with a pressure of 6 kg, at this time, one of the second valve 423 and the third valve 425 is alternately opened, when the second valve 423 is opened, the U-shaped bend 421 can be backflushed, when the third valve 425 is opened, the pipeline on the left side of the third valve 425 can be backflushed, the U-shaped bend 421 is most prone to being blocked, therefore, the U-shaped bend 421 should be backflushed more frequently, when the U-shaped bend 421 is backflushed, there is a risk that the blocked pipeline impurities will be flushed into the inside of the condenser 41, which will cause damage to the condenser 41, affect the use effect and service life, therefore, the backflushing auxiliary box 43 is connected and installed at the first condensed liquid outlet 412 of the condenser 41 to solve the above problems, as shown in Figure 6As shown, the backflush auxiliary tank 43 includes a tank body 431, a second partition plate 434 and a third partition plate 437, the tank body 431 is communicated with the first condensate outlet 412 at the top, that is, the backflush auxiliary tank 43 is directly connected with the condenser 41, the tank body 431 is provided with a second condensate outlet 432 below, the second condensate outlet 432 is arranged in a staggered manner with the first condensate outlet 412, the inlet end of the U-shaped bend 421 is connected with the second condensate outlet 432, the condensate first enters the backflush auxiliary tank 43, and then enters the U-shaped bend 421 through the second condensate outlet 432, the filter 433 is installed in the tank body 431 at the second condensate outlet 432, the filter 433 can form a certain impurity filtering efficiency for the condensate, so as to reduce the probability of pipe blockage of the U-shaped bend 421, of course, the filter 433 also has a risk of being blocked due to the dirt layer on the screen surface, the second partition plate 434 is installed in the tank body 431, a second liquid level detection cavity 435 is formed in the tank body 431 through the second partition plate 434, the bottom of the second liquid level detection cavity 435 is communicated with the inner cavity of the tank body 431, the liquid level in the second liquid level detection cavity 435 is the liquid level in the inner cavity of the tank body 431, after the U-shaped bend 421 or the filter 433 is blocked, the liquid level in the inner cavity of the tank body 431 rises, driving the liquid level in the second liquid level detection cavity 435 to rise, the second liquid level gauge 436 is installed in the second liquid level detection cavity 435, the second liquid level gauge 436 can find the pipe blockage fault by detecting the liquid level, so as to send an alarm signal, the second partition plate 43 has a similar effect with the first partition plate 121, and has an anti-interference effect, after the pipe blockage fault alarm signal is sent, the second backflush pipe line 424 is controlled to operate the backflush pipeline, in the backflush operation, it is necessary to prevent the dirt and impurities from directly entering the condenser 41, therefore, the second condensate outlet 432 is arranged in a staggered manner with the first condensate outlet 412, so as to reduce the risk of impurities entering the condenser 41 through the first condensate outlet 412, the third partition plate 437 is fixedly installed in the tank body 431, the third partition plate 437 only has a bottom edge which does not contact with the inner wall of the tank body 431, that is, the existence of the third partition plate 437 does not affect the flow of the condensate at the bottom of the tank body 431, the tank body 431 is designed to be fixedly installed with a flow dispersing cone 438, the flow dispersing cone 438 is installed with the tapered tip downward, the flow dispersing cone 438 is arranged directly above the second condensate outlet 432, when the backflush pipe line is in operation, the dirt and impurities are sprayed upward from the second condensate outlet 432, and meet the flow dispersing cone 438 to form an umbrella-shaped scattering effect, the third partition plate 437 is arranged on the side of the flow dispersing cone 438, and the flow dispersing cone 438 is located between the third partition plate 437 and the inner wall of the tank body 431, the umbrella-shaped scattering is blocked by the third partition plate 437 to form natural falling, 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, so that the operation of the backflush pipe line will not cause negative problems, the backflush auxiliary tank 43 is provided with a cleaning port 439 on the side surface and the bottom surface,The cleaning port 439 is parallel to the sealing closing, and needs to be opened after each shift to clean the box.

[0034] As shown in Figure 2 The centrifugal separator 1 is provided with a cleaning pipeline 15, which is designed with air replacement and methanol cleaning parts. The centrifugal separator 1 needs to be cleaned before and after work. First, fresh methanol liquid is sprayed to clean the drum part, 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 work of the centrifugal separator 1 to ensure the stability of the internal environment, as shown in Figure 6 The backflush auxiliary box 43 is also designed with an air replacement pipeline. Before the backflush auxiliary box 43 is opened, 0.1 kg pressure nitrogen needs to be introduced to replace the air in the box.

[0035] A separation and decolorization method for regenerating DMT, which is realized by using a separation and decolorization system for regenerating DMT, comprising the following steps:

[0036] (a) The DMT crude material produced by the ester exchange reaction is transported to the first separation and decolorization unit 100 through a pipeline. The DMT crude material is transported into the centrifugal separator 1 through the pipeline. After the centrifugal separation operation, the liquid material is output from the separation liquid output pipeline 2 through the liquid phase outlet 12, realizing the first impurity separation. The solid material is output to the DMT dilution tank 3 through the solid phase outlet 13. The solid material completes the cleaning and dilution operation in the DMT dilution tank 3, forming the first diluted DMT solution. The gaseous material is output to the condensation treatment device 4 through the gas phase outlet 14. The condensed liquid is returned to the liquid phase outlet 12 through the reflux pipeline 42 and is output from the separation liquid output pipeline 2;

[0037] (b) The DMT solution diluted in the DMT dilution tank 3 of the first separation and decolorization unit 100 is transported into the centrifugal separator 1 of the second separation and decolorization unit 100 through a serial pipeline, repeating step a. The second diluted DMT solution is formed in the DMT dilution tank 3 of the second separation and decolorization unit 100;

[0038] (c) The DMT solution diluted in the DMT dilution tank 3 of the second separation and decolorization unit 100 is transported into the centrifugal separator 1 of the third separation and decolorization unit 100 through a serial pipeline, repeating step a. The third diluted DMT solution is formed in the DMT dilution tank 3 of the third separation and decolorization unit 100;

[0039] (d) The DMT solution diluted in the DMT dilution tank 3 of the second separation and decolorization unit 100 is transported to the melting storage unit 200 through a serial pipeline, and the DMT solution is heated by the heater 201 to form a molten state, and then the molten DMT solution is transported to the heat preservation storage tank 202 for heat preservation storage.

[0040] The DMT crude material can form a DMT product with good color quality (from black to light gray, the change of color represents less impurities and higher purity) and higher purity after three times of decolorization and purification by the present application. The separation and decolorization system of the present application is designed with a series of fault handling mechanisms to ensure stable and efficient operation.

[0041] The above only describes the preferred embodiments of the present application, and the protection scope of the present application is not limited to the above-mentioned embodiments. Any technical solutions falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present application shall also be considered as falling within the protection scope of the present application.

Claims

1. A system for separating and decolorizing regenerated DMT, characterized by, The application relates to a kind of melt storage units (200) and several separate decoloring units (100), several separate decoloring units (100) are sequentially connected in pipeline, melt storage unit (200) is connected in pipeline after last separate decoloring unit (100), and separate decoloring unit (100) includes centrifugal separator (1), DMT dilution tank (3) and condensation treatment device (4), centrifugal separator (1) is provided with material input port (11), liquid phase outlet (12), solid phase outlet (13) and gas phase outlet (14), the liquid phase outlet (12) is connected with separation liquid output pipeline (2), the solid phase outlet (13) is connected with DMT dilution tank (3) in pipeline, the gas phase outlet (14) is connected with condensation treatment device (4) in pipeline, the condensation treatment device (4) is provided with reflux pipeline (42), the reflux pipeline (42) is connected with the liquid phase outlet (12) of centrifugal separator (1), the outlet pipeline of DMT dilution tank (3) of previous separate decoloring unit (100) is connected to the material input port (11) of centrifugal separator (1) of rear separate decoloring unit (100), the outlet pipeline of DMT dilution tank (3) of last separate decoloring unit (100) is connected to melt storage unit (200), and the condensation treatment device (4) includes condenser (41), the condenser (41) is provided with gas phase inlet (411) and first condensed liquid outlet (412), the gas phase outlet (14) of centrifugal separator (1) is connected with the gas phase inlet (411) of condenser (41) in pipeline, one end of the reflux pipeline (42) is connected with the first condensed liquid outlet (412) of condenser (41), the other end of the reflux pipeline (42) is communicated with the liquid phase outlet (12) of centrifugal separator (1), the reflux pipeline (42) is provided with U-shaped bend (421), the first condensed liquid outlet (412) of condenser (41) is connected with installation backflush auxiliary box (43), the backflush auxiliary box (43) includes box (431), second partition (434) and third partition (437), the top of the box (431) is communicated with the first condensed liquid outlet (412), the box (431) is provided with second condensed liquid outlet (432), the second condensed liquid outlet (432) is disposed in position with the first condensed liquid outlet (412), the inlet end pipeline of the U-shaped bend (421) is connected with the second condensed liquid outlet (432), the second condensed liquid outlet (432) is installed with filter (433) in the box (431), the second partition (434) is installed in the box (431), and second liquid level detection cavity (435) is formed in the box (431) by the second partition (434), the bottom of the second liquid level detection cavity (435) is communicated with the inner chamber of the box (431), the second liquid level detection cavity (435) is installed with second liquid level meter (436), and the third partition (437) is fixedly installed in the box (431),The third partition plate (437) only has a bottom edge not in contact with the inner wall of the box (431), the box (431) is fixedly provided with a flow dispersing cone (438), the flow dispersing cone (438) is installed with the cone tip downward, the flow dispersing cone (438) is arranged directly above the second condensate outlet (432), the third partition plate (437) is arranged on the side of the flow dispersing cone (438), and the backflushing auxiliary box (43) is provided with a cleaning port (439) on the side surface and the bottom surface.

2. The system for separating and decolorizing regenerated DMT according to claim 1, wherein, The number of the separation and decolorization units (100) is three, the liquid phase outlet (12) of the centrifugal separator (1) is inverted conical, the separation liquid output pipeline (2) comprises a liquid discharge pipe (21) and a first liquid outlet pump (22), the upper end of the liquid discharge pipe (21) is vertically inserted into the liquid phase outlet (12), the lower end of the liquid discharge pipe (21) is connected to the inlet of the first liquid outlet pump (22), the top of the liquid discharge pipe (21) is open and forms a height difference with the bottom of the conical tip of the liquid phase outlet (12), and the centrifugal separator (1) is provided with a cleaning pipeline (15).

3. The system for separating and decolorizing regenerated DMT according to claim 1, wherein, A first baffle (121) is fixedly installed in the liquid phase outlet (12), the first baffle (121) divides the liquid phase outlet (12) to form a first liquid level detection cavity (122), a first liquid level meter (123) is installed in the first liquid level detection cavity (122), the first liquid level meter (123) is a floating ball type liquid level meter, and the first liquid level detection cavity (122) is connected with the inner cavity of the liquid phase outlet (12) at the lower end.

4. The system for separating and decolorizing regenerated DMT according to claim 2, wherein, A first valve (23) and a first back flushing pipeline (24) are installed on the connecting pipeline of the liquid discharge pipe (21) and the first liquid outlet pump (22), the first valve (23) is installed close to the inlet of the first liquid outlet pump (22), and the first back flushing pipeline (24) and the first valve (23) are opened and closed in interlocking control.

5. The system for separating and decolorizing regenerated DMT according to claim 1, wherein, A methanol input pipeline (31) is connected to the side of the DMT dilution tank (3), a spraying mechanism (32) is installed in the DMT dilution tank (3), the methanol input pipeline (31) is connected to the spraying mechanism (32), and the outlet of the DMT dilution tank (3) is arranged at the bottom of the DMT dilution tank (3).

6. The system for separating and decolorizing regenerated DMT according to claim 1, wherein, The U-shaped bend (421) is provided with a supplementary liquid pipeline (422), the inlet end and the outlet end of the U-shaped bend (421) are arranged according to the flow direction of the condensed liquid in the U-shaped bend (421), a second valve (423) is installed at the inlet end of the U-shaped bend (421), a second back flushing 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), and the second back flushing pipeline (424), the second valve (423) and the third valve (425) are opened and closed in interlocking control.

7. The system for separating and decolorizing regenerated DMT according to claim 1, wherein, The melting storage unit (200) comprises a heater (201) and a heat preservation storage tank (202) connected in sequence, 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 with the pipeline of the heat preservation storage tank (202).

8. A method for separating and decolorizing regenerated DMT, which is implemented by using the regenerated DMT separating and decolorizing system according to any one of claims 1-7, characterized in that, The method comprises the following steps: (a), the DMT crude material produced by the ester exchange reaction is transported by pipeline to the first separation and decolorization unit (100), the DMT crude material is transported into the centrifugal separator (1) through the pipeline, after the centrifugal separation operation, the liquid material is output from the separation liquid output pipeline (2) through the liquid phase outlet (12), the solid material is output to the DMT dilution tank (3) through the solid phase outlet (13), the solid material completes the cleaning and dilution operation in the DMT dilution tank (3), forming the first diluted DMT solution, the gaseous material is output to the condensation treatment device (4) through the gas phase outlet (14), the condensed liquid is returned to the liquid phase outlet (12) through the reflux pipeline (42), and is output from the separation liquid output pipeline (2); (b), the DMT solution diluted in the DMT dilution tank (3) of the first separation and decolorization unit (100) is transported into the centrifugal separator (1) of the second separation and decolorization unit (100) through the series pipeline, and the step (a) is repeated, forming the second diluted DMT solution in the DMT dilution tank (3) of the second separation and decolorization unit (100); (c), the DMT solution diluted in the DMT dilution tank (3) of the second separation and decolorization unit (100) is transported into the centrifugal separator (1) of the third separation and decolorization unit (100) through the series pipeline, and the step (a) is repeated, forming the third diluted DMT solution in the DMT dilution tank (3) of the third separation and decolorization unit (100); (d), the DMT solution diluted in the DMT dilution tank (3) of the second separation and decolorization unit (100) is transported into the melting storage unit (200) through the series pipeline, the DMT solution is heated by the heater (201) first, so that the DMT forms a molten state, and then the molten DMT solution is transported into the heat preservation storage tank (202) for heat preservation storage.

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