Treatment device and treatment method for PBT (polybutylene terephthalate) waste liquid

Abstract

The invention relates to a PBT waste liquid treatment device. The device comprises a PBT waste liquid input system; the normal-pressure rectification system comprises a normal-pressure tower, and the PBT waste liquid input system is communicated with the middle part of the normal-pressure tower; the high-pressure rectification system comprises a high-pressure tower, the tower top of the atmospheric tower is communicated with the middle part of the high-pressure tower, and the tower top of the high-pressure tower is communicated with the middle part of the atmospheric tower; the wastewater treatment system comprises a wastewater tower, and a tower kettle of the atmospheric tower is communicated with the middle part of the wastewater tower. The problem that the COD value of wastewater generated in the process of purifying THF from the PBT waste liquid is difficult to reduce is solved.

Description

Technical Field

[0001] The present application relates to the field of chemical industry, and in particular to the treatment of PBT waste liquid. Background Art

[0002] At present, almost all newly built polybutylene terephthalate (PBT) projects in China adopt the process of direct esterification of purified terephthalic acid (PTA) and 1,4-butanediol (BDO). The direct esterification method for producing PBT will produce a waste liquid containing tetrahydrofuran (THF) as a by-product (referred to as: PBT waste liquid in this application). The main components of PBT waste liquid are THF and water. At the same time, the waste liquid also contains a small amount of organic impurities such as BDO, PBT and dibasic acids. Recovering THF from PBT waste liquid can turn waste into treasure and increase the company's profits. At present, the main methods for recovering THF from PBT waste liquid include pressure swing distillation, distillation-membrane coupling method, etc. Wastewater will be generated in the process of recovering THF. Since the boiling point of impurities in PBT waste liquid is almost higher than the boiling point of water, impurities will be enriched in water, resulting in a high COD of wastewater (COD of about 25-40g / L).

[0003] In the prior art, when recovering THF from PBT waste liquid, there are few reports on the treatment of high COD wastewater. The following two methods are commonly used for industrial wastewater treatment: one method is to add a regulating tank, mix the low COD wastewater from various regions (such as circulating water sewage, laboratory wastewater, flushing water, initial rainwater, etc.) with high COD wastewater, reduce the COD of the wastewater to meet the requirements of the sewage treatment plant, and then discharge it to the sewage treatment plant; the other method is to design a sewage treatment system, which generally includes a hydrolysis acidification process, an anaerobic process, and an aerobic process, which can treat wastewater with a COD of 5g / L to below 0.3g / L, and then discharge it to the sewage treatment plant. However, the limitation of this method is that the COD of the wastewater entering the sewage treatment system is required to be approximately less than 10g / L.

[0004] However, the COD of the wastewater generated in the process of recovering THF from PBT waste liquid is relatively high (COD is about 25-40g / L), which shows that the wastewater cannot be directly treated by the sewage treatment system. On the other hand, due to the high COD of the wastewater, if the COD of the wastewater is adjusted to meet the requirements of the sewage treatment plant by using the regulating tank method, according to preliminary calculations, the flow rate of circulating water to discharge sewage is about 7.0 times the flow rate of the wastewater, that is, the total wastewater discharge has increased by 7.0 times, which not only requires a larger regulating tank space, but also increases the load of biochemical treatment.

[0005] Therefore, how to effectively reduce the COD of wastewater has always been a difficult problem to solve in this field. Summary of the invention

[0006] The embodiments of the present application provide a device and method for treating PBT waste liquid to solve the technical problem that the COD value of waste water generated during the process of recovering THF from PBT waste liquid is difficult to reduce.

[0007] In a first aspect, an embodiment of the present application provides a PBT waste liquid treatment device, the PBT waste liquid treatment device comprising:

[0008] PBT waste liquid input system;

[0009] An atmospheric distillation system, wherein the atmospheric distillation system comprises an atmospheric tower, and the PBT waste liquid input system is connected to the middle part of the atmospheric tower;

[0010] A high-pressure distillation system, the high-pressure distillation system comprising a high-pressure tower, the top of the atmospheric pressure tower being connected to the middle of the high-pressure tower, and the top of the high-pressure tower being connected to the middle of the atmospheric pressure tower;

[0011] A wastewater treatment system comprises a wastewater tower, wherein the bottom of the atmospheric pressure tower is connected to the middle of the wastewater tower.

[0012] In some embodiments of the present application, the atmospheric distillation system further comprises an atmospheric tower condenser, an atmospheric tower reflux tank, and an atmospheric tower reflux pump connected in sequence, wherein the atmospheric tower condenser is connected to the top of the atmospheric tower, and the atmospheric tower reflux pump is connected to the upper part of the atmospheric tower; and / or,

[0013] The atmospheric distillation system further comprises an atmospheric tower reboiler, one end of the atmospheric tower reboiler is connected to the bottom of the atmospheric tower, and the other end is connected to the lower part of the atmospheric tower.

[0014] The atmospheric distillation system further comprises an atmospheric tower kettle pump, one end of which is connected to the bottom of the atmospheric tower, and the other end of which is connected to the middle of the wastewater tower.

[0015] In some embodiments of the present application, the high-pressure distillation system further comprises a high-pressure tower heat exchanger, a high-pressure tower reflux tank, and a high-pressure tower reflux pump connected in sequence, wherein the high-pressure tower heat exchanger is connected to the top of the high-pressure tower, and the high-pressure tower reflux pump is connected to the upper part of the high-pressure tower; and / or,

[0016] The high-pressure distillation system further comprises a high-pressure tower reboiler, one end of the high-pressure tower reboiler is connected to the bottom of the high-pressure tower, and the other end of the high-pressure tower reboiler is connected to the lower part of the high-pressure tower.

[0017] In some embodiments of the present application, the PBT waste liquid input system is connected to the middle part of the atmospheric pressure tower through the high-pressure tower heat exchanger.

[0018] In some embodiments of the present application, the wastewater treatment system further comprises a wastewater tower condenser, a wastewater tower reflux tank, and a wastewater tower reflux pump which are connected in sequence, wherein the wastewater tower condenser is connected to the top of the wastewater tower, and the wastewater tower reflux pump is connected to the upper part of the wastewater tower; and / or,

[0019] The wastewater distillation system further comprises a wastewater tower reboiler, one end of the wastewater tower reboiler is connected to the bottom of the wastewater tower, and the other end is connected to the lower part of the wastewater tower.

[0020] In some embodiments of the present application, the wastewater treatment system also includes a wastewater tower heat exchanger, which is connected in parallel to both ends of the wastewater tower condenser, and the top of the atmospheric pressure tower is connected to the middle of the high-pressure tower through the wastewater tower heat exchanger.

[0021] In a second aspect, an embodiment of the present application provides a method for treating PBT waste liquid, the method being implemented by the PBT waste liquid treatment device described in any embodiment of the first aspect, the method comprising the following steps:

[0022] Inputting PBT waste liquid into the middle of the atmospheric pressure tower through the PBT waste liquid input system for atmospheric distillation;

[0023] The low-boiling products of THF and water extracted from the top of the atmospheric tower are input into the middle of the high-pressure tower for high-pressure distillation, and the primary wastewater extracted from the bottom of the atmospheric tower is input into the middle of the wastewater tower;

[0024] The high boiling products of THF and water taken out from the top of the high pressure tower are circulated back to the middle part of the atmospheric pressure tower, and the THF product in the kettle of the high pressure tower is taken out and collected;

[0025] The secondary wastewater from the top of the wastewater tower is extracted, and the concentrated liquid from the bottom of the wastewater tower is extracted.

[0026] In some embodiments of the present application, the operating pressure of the atmospheric pressure tower is 60-180 kPaA, the reflux ratio is 0.5-3, the temperature of the tower top is 45-90°C, and the temperature of the tower bottom is 80-120°C.

[0027] In some embodiments of the present application, the operating pressure of the high-pressure tower is 200-950 kPaA, the reflux ratio is 0.5-5, the temperature of the tower top is 90-150°C, and the temperature of the tower bottom is 120-160°C.

[0028] In some embodiments of the present application, the operating pressure of the wastewater tower is 200-850 kPaA, the reflux ratio is 0.1-3, the temperature of the tower top is 100-170°C, and the temperature of the tower bottom is 110-190°C.

[0029] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0030] The treatment device and method for PBT waste liquid provided in the embodiment of the present application, by inputting the primary waste water extracted from the bottom of the atmospheric tower into the waste water tower for distillation separation, after treating the primary waste water with a COD of 25 to 40 g / L, extracting the secondary waste water with a COD of 0.7 to 2 g / L from the top of the waste water tower, and extracting the concentrated liquid containing high concentrations of PBT and adipic acid from the bottom of the waste water tower, the secondary waste water can be directly subjected to sewage treatment, and the concentrated liquid can be further treated, thereby solving the problem that the COD value of the waste water generated in the process of recovering THF from PBT waste liquid is difficult to reduce. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0033] Figure 1 A schematic diagram of the structure of a PBT waste liquid treatment device provided in an embodiment of the present application.

[0034] The numbers in the drawings of the present application are: 1-atmospheric pressure tower, 2-atmospheric pressure tower condenser, 3-atmospheric pressure tower reflux tank, 4-atmospheric pressure tower reflux pump, 5-atmospheric pressure tower reboiler, 6-atmospheric pressure tower kettle pump, 7-high-pressure tower, 8-high-pressure tower heat exchanger, 9-high-pressure tower reflux tank, 10-high-pressure tower reflux pump, 11-high-pressure tower reboiler, 12-wastewater tower, 13-wastewater tower heat exchanger, 14-wastewater tower condenser, 15-wastewater tower reflux tank, 16-wastewater tower reflux pump, 17-wastewater tower reboiler. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0036] Unless otherwise specified, the terms used herein should be understood as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. In the event of a conflict, this specification takes precedence.

[0037] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0038] There is a technical problem that the COD value of the wastewater generated in the process of recovering THF from PBT waste liquid is difficult to reduce.

[0039] The technical solution provided by the embodiments of the present application is to solve the above technical problems, and the overall idea is as follows:

[0040] In the first aspect, the present application embodiment provides a PBT waste liquid treatment device, please refer to Figure 1 , the PBT waste liquid treatment device comprises:

[0041] PBT waste liquid input system;

[0042] An atmospheric distillation system, wherein the atmospheric distillation system comprises an atmospheric tower 1, and the PBT waste liquid input system is connected to the middle part of the atmospheric tower 1;

[0043] A high-pressure distillation system, wherein the high-pressure distillation system comprises a high-pressure tower 7, the top of the atmospheric pressure tower 1 is connected to the middle of the high-pressure tower 7, and the top of the high-pressure tower 7 is connected to the middle of the atmospheric pressure tower 1;

[0044] The wastewater treatment system comprises a wastewater tower 12 , and the bottom of the atmospheric pressure tower 1 is connected to the middle of the wastewater tower 12 .

[0045] Those skilled in the art can understand that the PBT waste liquid input system at least includes a pipeline for inputting the PBT waste liquid; it can also include instruments such as a pressure gauge and a thermometer.

[0046] The function of the atmospheric distillation system is to evaporate the low-boiling substances of THF and water, and the evaporated low-boiling substances enter the high-pressure distillation system.

[0047] The function of the high-pressure distillation system is to evaporate the high-boiling products of THF and water. The high-boiling products of THF and water extracted from the top of the high-pressure tower 7 are circulated back to the atmospheric pressure tower 1.

[0048] The function of the wastewater treatment system is to distill and separate the wastewater. The primary wastewater extracted from the bottom of the atmospheric tower 1 is input into the wastewater tower 12 for distillation, the secondary wastewater is extracted from the top of the wastewater tower 12, and the concentrated liquid is extracted from the bottom of the tower. The COD of the primary wastewater is generally 25-40g / L, and the COD of the secondary wastewater can be reduced to 0.7-2g / L. The concentrated liquid contains high concentrations of PBT, adipic acid and other substances, which can be sent to qualified units for further incineration treatment, and no longer imposes a burden on sewage treatment.

[0049] In some embodiments of the present application, in order to simplify the connecting pipelines, a feed port connected to the PBT waste liquid input system is provided in the middle of the atmospheric pressure tower 1, and the top of the high-pressure tower 7 is connected to the feed port together with the waste liquid input system.

[0050] In the present application, the primary wastewater extracted from the bottom of the atmospheric tower 1 is input into the wastewater tower 12 for distillation separation. After the primary wastewater with a COD of 25 to 40 g / L is treated, secondary wastewater with a COD of 0.7 to 2 g / L is extracted from the top of the wastewater tower 12, and a concentrated liquid containing high-concentration PBT and adipic acid is extracted from the bottom of the wastewater tower 12. The secondary wastewater can be directly treated as sewage, and the concentrated liquid can be further treated, thereby solving the problem that the COD value of the wastewater generated in the process of recovering THF from the PBT waste liquid is difficult to reduce.

[0051] This application can also be supplied in a skid mode, which has the advantages of high integration and few on-site modifications.

[0052] In some embodiments of the present application, the atmospheric distillation system further includes an atmospheric tower condenser 2, an atmospheric tower reflux tank 3, and an atmospheric tower reflux pump 4 connected in sequence, wherein the atmospheric tower condenser 2 is connected to the top of the atmospheric tower 1, and the atmospheric tower reflux pump 4 is connected to the upper part of the atmospheric tower 1; and / or,

[0053] The atmospheric distillation system further comprises an atmospheric tower reboiler 5, one end of the atmospheric tower reboiler 5 is connected to the bottom of the atmospheric tower, and the other end is connected to the lower part of the atmospheric tower.

[0054] The atmospheric distillation system further comprises an atmospheric tower kettle pump 6, one end of which is connected to the bottom of the atmospheric tower, and the other end of which is connected to the middle of the wastewater tower.

[0055] Those skilled in the art can understand that the functions of the atmospheric tower condenser 2, atmospheric tower reflux tank 3, and atmospheric tower reflux pump 4 are to reflux a portion of the low-boiling substances at the top of the atmospheric tower 1. The function of the atmospheric tower reboiler 5 is to reboil a portion of the primary wastewater in the tower bottom of the atmospheric tower 1. The function of the atmospheric tower bottom pump 6 is to input the primary wastewater extracted from the tower bottom of the atmospheric tower 1 into the wastewater tower 12.

[0056] In some embodiments of the present application, the high-pressure distillation system further includes a high-pressure tower heat exchanger 8, a high-pressure tower reflux tank 9, and a high-pressure tower reflux pump 10 connected in sequence, wherein the high-pressure tower heat exchanger 8 is connected to the top of the high-pressure tower 7, and the high-pressure tower reflux pump 10 is connected to the upper part of the high-pressure tower 7; and / or,

[0057] The high-pressure distillation system further includes a high-pressure tower reboiler 11 , one end of which is connected to the bottom of the high-pressure tower, and the other end of which is connected to the lower part of the high-pressure tower.

[0058] Those skilled in the art can understand that the functions of the high-pressure tower heat exchanger 8, the high-pressure tower reflux tank 9, and the high-pressure tower reflux pump 10 are to reflux a portion of the high-boiling products at the top of the high-pressure tower 7. The function of the high-pressure tower reboiler 11 is to reboil a portion of the THF product in the bottom of the high-pressure tower 7. The high-pressure tower heat exchanger 8 can achieve the purpose of condensation by heat exchange.

[0059] In some embodiments of the present application, the PBT waste liquid input system is connected to the middle part of the atmospheric pressure tower 1 through the high-pressure tower heat exchanger 8 .

[0060] Those skilled in the art will appreciate that the heat exchange between the PBT waste liquid and the high-boiling products at the top of the high-pressure tower 7 in the high-pressure tower heat exchanger 8 can achieve preheating of the PBT waste liquid and condensation of the high-boiling products, thereby reducing the energy consumption of the device.

[0061] In some embodiments of the present application, after the high-boiling products at the top of the high-pressure tower 7 pass through the high-pressure tower heat exchanger 8, the high-pressure tower reflux tank 9, and the high-pressure tower reflux pump 10, a portion of the high-boiling products reflux to the high-pressure tower 7, and the other portion of the high-boiling products is input into the atmospheric distillation tower system together with the PBT waste liquid, thereby achieving communication with the middle part of the atmospheric pressure tower 1.

[0062] In some embodiments of the present application, the wastewater treatment system further includes a wastewater tower condenser 14, a wastewater tower reflux tank 15, and a wastewater tower reflux pump 16 which are connected in sequence, wherein the wastewater tower condenser 14 is connected to the top of the wastewater tower 12, and the wastewater tower reflux pump 16 is connected to the upper part of the wastewater tower 12; and / or,

[0063] The wastewater distillation system further includes a wastewater tower reboiler 17 , one end of which is connected to the bottom of the wastewater tower, and the other end of which is connected to the lower part of the wastewater tower.

[0064] Those skilled in the art can understand that the wastewater tower condenser 14, the wastewater tower reflux tank 15, and the wastewater tower reflux pump 16 are used to reflux a portion of the secondary wastewater at the top of the wastewater tower 12. The wastewater tower reboiler 17 is used to reboil a portion of the concentrated liquid in the bottom of the wastewater tower 12.

[0065] In some embodiments of the present application, the wastewater treatment system also includes a wastewater tower heat exchanger 13, which is connected in parallel to both ends of the wastewater tower condenser 14, and the top of the atmospheric pressure tower 1 is connected to the middle of the high-pressure tower 7 through the wastewater tower heat exchanger 13.

[0066] Those skilled in the art can understand that the low-boiling substances of THF and water extracted from the top of the atmospheric tower 1 are heat exchanged with the secondary wastewater in the wastewater tower heat exchanger 13, so as to achieve preheating of the low-boiling substances and condensation of the secondary wastewater. The secondary wastewater condensed in the wastewater tower heat exchanger 13 is combined with the secondary wastewater condensed in the wastewater tower condenser 14 and enters the wastewater tower reflux tank 15.

[0067] In some embodiments of the present application, the bottom extraction of the atmospheric pressure tower 1 is connected to the middle part of the wastewater tower 12 through the atmospheric pressure tower bottom pump 6 .

[0068] In a second aspect, an embodiment of the present application provides a method for treating PBT waste liquid, the method being implemented by the PBT waste liquid treatment device described in any embodiment of the first aspect, the method comprising the following steps:

[0069] S1: Inputting PBT waste liquid into the middle of the atmospheric pressure tower 1 through the PBT waste liquid input system for atmospheric distillation;

[0070] S2: The low-boiling products of THF and water extracted from the top of the atmospheric tower 1 are input into the middle of the high-pressure tower 7 for high-pressure distillation, and the primary wastewater extracted from the bottom of the atmospheric tower 1 is input into the middle of the wastewater tower 12;

[0071] S3: circulating the high boiling products of THF and water taken out from the top of the high pressure tower 7 back to the middle of the atmospheric pressure tower 1, and collecting the THF product in the bottom of the high pressure tower 7;

[0072] S4: The secondary wastewater from the top of the wastewater tower 12 is extracted, and the concentrated liquid from the bottom of the wastewater tower 12 is extracted.

[0073] Those skilled in the art can understand that there is no order of precedence between step S3 and step S4, and they are generally performed simultaneously.

[0074] In some embodiments of the present application, the operating pressure of the atmospheric pressure tower 1 is 60-180 kPaA, the reflux ratio is 0.5-3, the temperature of the tower top is 45-90°C, and the temperature of the tower bottom is 80-120°C.

[0075] In some embodiments of the present application, the operating pressure of the high-pressure tower 7 is 200-950 kPaA, the reflux ratio is 0.5-5, the temperature of the tower top is 90-150°C, and the temperature of the tower bottom is 120-160°C.

[0076] In some embodiments of the present application, the operating pressure of the wastewater tower 12 is 200-850 kPaA, the reflux ratio is 0.1-3, the temperature of the tower top is 100-170°C, and the temperature of the tower bottom is 110-190°C.

[0077] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0078] Example

[0079] PBT waste liquid from a PBT production device is provided, wherein various parameters of the PBT waste liquid are: temperature 30° C., pressure 200 kPaA, flow rate 300 kg / h, THF content 34.4 wt %, water content 64.4 wt %, PBT content 0.6 wt %, and adipic acid content 0.6 wt % in the waste liquid.

[0080] The PBT waste liquid is first heated by the high-pressure tower heat exchanger 8 and then enters the atmospheric pressure tower 1 for distillation, wherein the atmospheric pressure tower 1 has an operating pressure of 108 kPaA, 20 theoretical plates, a mass reflux ratio of 2.0, a tower top temperature of 65.2°C, and a tower bottom temperature of 99.2°C.

[0081] After condensation, the low-boiling substances in the gas phase at the top of the atmospheric tower 1 enter the atmospheric tower reflux tank 3. After the condensate in the atmospheric tower reflux tank 3 is pressurized by the atmospheric tower reflux pump 4, one stream is used as the reflux of the atmospheric tower 1, and the other stream enters the high-pressure tower 7 after being heated by the wastewater tower heat exchanger 13. The operating pressure of the high-pressure tower 7 is 800 kPaA, the number of theoretical plates is 20, the mass reflux ratio is 2.5, the tower top temperature is 134.2°C, and the tower bottom temperature is 146.7°C.

[0082] The COD of the primary wastewater from the bottom of the atmospheric tower 1 was tested to be about 31.6 g / L. The primary wastewater was pressurized by the atmospheric tower bottom pump 6 and then entered the wastewater tower 12. The operating pressure of the wastewater tower 12 was 600 kPaA, the number of theoretical plates was 20, the mass reflux ratio was 0.3, the tower top temperature was 150.4°C, and the bottom temperature was 175.5°C.

[0083] The high-boiling gas phase at the top of the high-pressure tower 7 is condensed by the high-pressure tower heat exchanger 8 and enters the high-pressure tower reflux tank 9. The condensate in the high-pressure tower reflux tank 9 is pressurized by the high-pressure tower reflux pump 10, one part is used as the reflux of the high-pressure tower 7, and the other part is mixed with the PBT waste liquid from the PBT production device and enters the high-pressure tower heat exchanger 8. The qualified THF product with a flow rate of 102.3 kg / h, a mass fraction of 99.89 wt%, and a yield of 99.0% can be obtained at the bottom of the high-pressure tower 7.

[0084] The gas phase at the top of the wastewater tower 12 is divided into two parts: one part of the gas phase is condensed and enters the wastewater tower reflux tank 15 after preheating the feed of the high-pressure tower 7 through the wastewater tower heat exchanger 13. The other part of the gas phase is condensed in the wastewater tower condenser 14 and then condensed and enters the wastewater tower reflux tank 15. The condensate in the wastewater tower reflux tank 15, i.e., the secondary wastewater, is pressurized by the wastewater tower reflux pump 16, one part is used as the reflux of the wastewater tower 12, and the other part is sent to the sewage treatment plant for treatment after meeting the sewage discharge requirements, wherein the COD of the wastewater is about 0.9g / L; a small amount of concentrated liquid extracted from the bottom of the wastewater tower 12 is sent to a qualified unit for incineration treatment, and the PBT content, adipic acid content, and water content in the concentrated liquid are about 37.8wt%, about 37.8wt%, and about 24.4wt%.

[0085] According to calculations, if the wastewater is not distilled and separated through the wastewater treatment system, in order to reduce the COD of the primary wastewater to meet the takeover requirements of the sewage treatment plant, the flow rate of circulating water to discharge sewage is about 7.0 times the flow rate of wastewater produced from the kettle of atmospheric pressure tower 1, that is, the total wastewater discharge is increased by 7.0 times, which not only requires a larger regulating tank space, but also increases the load of biochemical treatment.

[0086] This embodiment controls the COD of secondary wastewater to 0.9 g / L while ensuring the yield of qualified THF products is 99.0%, greatly reducing the difficulty and load of biochemical treatment. In addition, the design of the high-pressure tower heat exchanger 8 and the wastewater tower heat exchanger 13 saves about 25% of steam consumption.

[0087] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0088] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "include", "comprise", etc. refer to "including but not limited to". Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "include..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. For the association relationship of more than three associated objects described by "and / or", it means that any one of these three associated objects can exist alone, or any at least two of them exist at the same time. For example, for A, and / or B, and / or C, it can be represented that any one of A, B, and C exists alone, or any two of them exist at the same time, or three of them exist at the same time. In this article, "at least one" refers to one or more, and "multiple" refers to two or more. "At least one", "the following at least one (individual)" or similar expressions refer to any combination of these items, including any combination of single items (individual) or plural items (individual). For example, "at least one (individual) of a, b or c", or "at least one (individual) of a, b and c", can all represent: a, b, c, ab (i.e. a and b), ac, bc or abc, wherein a, b, c can be single or multiple, respectively.

[0089] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A PBT waste liquid treatment device, characterized in that: The processing device of the PBT waste liquid comprises: PBT waste liquid input system; An atmospheric distillation system, wherein the atmospheric distillation system comprises an atmospheric tower, and the PBT waste liquid input system is connected to the middle part of the atmospheric tower; A high-pressure distillation system, the high-pressure distillation system comprising a high-pressure tower, the top of the atmospheric pressure tower being connected to the middle of the high-pressure tower, and the top of the high-pressure tower being connected to the middle of the atmospheric pressure tower; A wastewater treatment system comprises a wastewater tower, wherein the bottom of the atmospheric pressure tower is connected to the middle of the wastewater tower.

2. The PBT waste liquid treatment device according to claim 1, characterized in that: The atmospheric distillation system further comprises an atmospheric tower condenser, an atmospheric tower reflux tank, and an atmospheric tower reflux pump which are connected in sequence, wherein the atmospheric tower condenser is connected to the top of the atmospheric tower, and the atmospheric tower reflux pump is connected to the upper part of the atmospheric tower; and / or, The atmospheric distillation system further comprises an atmospheric tower reboiler, one end of the atmospheric tower reboiler is connected to the bottom of the atmospheric tower, and the other end is connected to the lower part of the atmospheric tower. The atmospheric distillation system further comprises an atmospheric tower kettle pump, one end of which is connected to the bottom of the atmospheric tower, and the other end of which is connected to the middle of the wastewater tower.

3. The PBT waste liquid treatment device according to claim 1, characterized in that: The high-pressure distillation system further comprises a high-pressure tower heat exchanger, a high-pressure tower reflux tank, and a high-pressure tower reflux pump which are connected in sequence, wherein the high-pressure tower heat exchanger is connected to the top of the high-pressure tower, and the high-pressure tower reflux pump is connected to the upper part of the high-pressure tower; and / or, The high-pressure distillation system further comprises a high-pressure tower reboiler, one end of the high-pressure tower reboiler is connected to the bottom of the high-pressure tower, and the other end of the high-pressure tower reboiler is connected to the lower part of the high-pressure tower.

4. The PBT waste liquid treatment device according to claim 3, characterized in that: The PBT waste liquid input system is connected to the middle part of the atmospheric pressure tower through the high-pressure tower heat exchanger.

5. The PBT waste liquid treatment device according to claim 1, characterized in that: The wastewater treatment system further comprises a wastewater tower condenser, a wastewater tower reflux tank, and a wastewater tower reflux pump which are connected in sequence, wherein the wastewater tower condenser is connected to the top of the wastewater tower, and the wastewater tower reflux pump is connected to the upper part of the wastewater tower; and / or, The wastewater distillation system further comprises a wastewater tower reboiler, one end of the wastewater tower reboiler is connected to the bottom of the wastewater tower, and the other end is connected to the lower part of the wastewater tower.

6. The PBT waste liquid treatment device according to claim 5, characterized in that: The wastewater treatment system further comprises a wastewater tower heat exchanger, which is connected in parallel with both ends of the wastewater tower condenser, and the top of the atmospheric pressure tower is connected to the middle of the high pressure tower through the wastewater tower heat exchanger.

7. A method for treating PBT waste liquid, characterized in that: The method is implemented by the PBT waste liquid treatment device according to any one of claims 1 to 6, and the method comprises the following steps: Inputting PBT waste liquid into the middle of the atmospheric pressure tower through the PBT waste liquid input system for atmospheric distillation; The low-boiling products of THF and water extracted from the top of the atmospheric tower are input into the middle of the high-pressure tower for high-pressure distillation, and the primary wastewater extracted from the bottom of the atmospheric tower is input into the middle of the wastewater tower; The high boiling products of THF and water taken out from the top of the high pressure tower are circulated back to the middle part of the atmospheric pressure tower, and the THF product taken out from the bottom of the high pressure tower is collected; The secondary wastewater from the top of the wastewater tower is extracted, and the concentrated liquid from the bottom of the wastewater tower is extracted.

8. The method for treating PBT waste liquid according to claim 7, characterized in that: The operating pressure of the atmospheric pressure tower is 60-180 kPaA, the reflux ratio is 0.5-3, the temperature of the tower top is 45-90°C, and the temperature of the tower bottom is 80-120°C.

9. The method for treating PBT waste liquid according to claim 7, characterized in that: The operating pressure of the high-pressure tower is 200-950 kPaA, the reflux ratio is 0.5-5, the temperature of the tower top is 90-150°C, and the temperature of the tower bottom is 120-160°C.

10. The method for treating PBT waste liquid according to claim 7, characterized in that: The operating pressure of the wastewater tower is 200-850 kPaA, the reflux ratio is 0.1-3, the temperature of the tower top is 100-170°C, and the temperature of the tower bottom is 110-190°C.

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