A plasticizer wastewater treatment device and a wastewater treatment method thereof

Abstract

The application relates to a plasticizer wastewater treatment device and a wastewater treatment method thereof. The device comprises a wastewater conveying pipe, a rectifying tower communicated with the wastewater conveying pipe, a reboiling circulation pipe arranged on the rectifying tower, a first stop valve, a first booster pump, a reboiler and a first online chromatograph arranged on the reboiling circulation pipe, a first buffer tank communicated with the reboiling circulation pipe, an acidification reaction kettle, a first centrifuge, the first centrifuge, a first concentration reaction kettle and a second buffer tank, the second buffer tank and the first concentration reaction kettle being connected through a first concentrated liquid conveying pipe, a second concentrated liquid conveying pipe arranged on the first concentrated liquid conveying pipe, a third buffer tank communicated with the second concentrated liquid conveying pipe, the third buffer tank being communicated with the acidification reaction kettle, and an electrolytic tank, a second concentration reaction kettle, a crystallization tank and a second centrifuge being sequentially communicated with the second buffer tank. Organic acid and sodium sulfate are separated from the wastewater, the application is convenient to use, and has a wide market prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of plasticizer wastewater treatment, in particular to a plasticizer wastewater treatment device and a wastewater treatment method thereof. BACKGROUND

[0002] Plasticizer, also known as plasticizer, is a high polymer material additive widely used in industrial production. The addition of plasticizer to polymer materials can improve the performance of high polymer materials, reduce production cost and improve production efficiency. It is an important chemical product, which is widely used as an additive in plastic products, even in cosmetics and cleaning agents, especially in polyvinyl chloride plastic products. In order to increase the plasticity of plastic and improve the strength of plastic, phthalate needs to be added. The commonly used plasticizers include phthalate plasticizers, citric acid plasticizers, p-benzenes plasticizers and cyclohexane dicarboxylic acid ester plasticizers.

[0003] In the production process of the above-mentioned plasticizers, organic anhydride or organic acid is reacted with alcohol under the catalysis of sulfuric acid, and then sodium hydroxide solution is used for neutralization. Therefore, a large amount of wastewater containing salt and organic matter is generated in the production process. After neutralization, most enterprises recover part of the alcohol by simple distillation, and then use three-effect evaporation or steam mechanical recompression technology (MVR) to concentrate the wastewater to obtain high-concentration waste liquid or further dry the solid waste. These waste liquids contain high-concentration organic matter mainly composed of organic anhydride and high-concentration inorganic matter mainly composed of sodium sulfate. Taking the most common phthalate plasticizer as an example, phthalic anhydride is a low-toxicity hazardous product, which has irritant effect on skin and mucous membrane, and has the risk of causing combustion when it meets high heat, open flame or oxidizing agent. The waste salt containing a large amount of organic anhydride obtained by conventional method is a toxic hazardous product, which cannot be directly discharged according to the safety production regulations of enterprises, and also has the risk of spontaneous combustion when stored in open air in summer, causing unstable dangerous source. Furthermore, as one of the important raw materials for synthesizing plasticizers, organic anhydride has not been maximally and rationally utilized, which will increase the production cost of enterprises. Therefore, the conventional plasticizer wastewater treatment device and wastewater treatment method have defects, and cannot be reasonably popularized and applied. SUMMARY

[0004] In view of the defects of the prior art, the present application provides a plasticizer wastewater treatment device and a wastewater treatment method thereof, which can separate organic acid and sodium sulfate from plasticizer wastewater, facilitate further treatment of wastewater residue by using existing wastewater treatment devices, improve the step-by-step recovery of organic acid and sodium sulfate, and reduce the production cost of enterprises, so as to overcome the defects in the prior art.

[0005] The technical scheme adopted by the present application is as follows: a plasticizer wastewater treatment device, comprising a wastewater conveying pipe, a rectifying tower being communicated with the outlet end of the wastewater conveying pipe, a reboiling circulation pipe being arranged on the rectifying tower, a first stop valve, a first booster pump, a reboiler and a first on-line densimeter being sequentially arranged on the reboiling circulation pipe along the direction from the inlet end of the reboiling circulation pipe to the outlet end of the reboiling circulation pipe, the reboiling circulation pipe between the first booster pump and the reboiler being communicated with the inlet end of a first buffer tank, the outlet end of the first buffer tank being communicated with an acidification reaction kettle, the lower portion of the acidification reaction kettle being communicated with the inlet end of a first centrifuge, the liquid phase outlet end of the first centrifuge being communicated with a first concentration reaction kettle, the outlet end of the first concentration reaction kettle being communicated with a second buffer tank, the second buffer tank and the first concentration reaction kettle being communicated through a first concentrated liquid conveying pipe, the first concentrated liquid conveying pipe being provided with a second concentrated liquid conveying pipe, the outlet end of the second concentrated liquid conveying pipe being communicated with a third buffer tank, the third buffer tank and the acidification reaction kettle being communicated, the outlet end of the second buffer tank being sequentially communicated with an electrolytic cell, a second concentration reaction kettle, a crystallization tank and a second centrifuge.

[0006] Preferably, the rectifying tower is provided with a first liquefied water conveying pipe, the first liquefied water conveying pipe is provided with a heat source channel of a second heat exchanger, the outlet end of the first liquefied water conveying pipe is provided with a lye preparation tank, the first liquefied water conveying pipe between the lye preparation tank and the second heat exchanger is provided with a second liquefied water conveying pipe, the first liquefied water conveying pipe between the second liquefied water conveying pipe and the lye preparation tank and the second liquefied water conveying pipe are respectively provided with first adjusting valves, the lye preparation tank is provided with a stirring device, and the lye preparation tank, the acidification reaction kettle and the first concentration reaction kettle are respectively provided with acidity meters.

[0007] Preferably, the rectifying tower comprises a tower body, the tower body is sequentially provided with a first filler layer and a second filler layer from top to bottom, the tower body between the first filler layer and the second filler layer is communicated with the wastewater conveying pipe, the wastewater conveying pipe is provided with a cold source channel of a first heat exchanger, the inlet end of the cold source channel of the first heat exchanger is communicated with the top end of the tower body, the outlet end of the cold source channel of the first heat exchanger is communicated with a gas-liquid separation tank, the liquid phase outlet end of the gas-liquid separation tank is communicated with the tower body above the first filler layer through a crude alcohol reflux pipe, the crude alcohol reflux pipe is provided with a second adjusting valve, the crude alcohol reflux pipe between the second adjusting valve and the gas-liquid separation tank is provided with a crude alcohol conveying pipe, and the crude alcohol conveying pipe is provided with a third adjusting valve.

[0008] Preferably, the first concentrated liquid delivery pipe is sequentially provided with a second booster pump, a fourth regulating valve and a first check valve in the direction from the first concentration reactor to the second buffer tank, the electrolytic cell and the second buffer tank are connected through a third concentrated liquid delivery pipe, the third concentrated liquid delivery pipe is sequentially provided with a third booster pump and a fifth regulating valve in the direction from the second buffer tank to the electrolytic cell, the third concentrated liquid delivery pipe between the third booster pump and the fourth regulating valve is connected with the first concentrated liquid delivery pipe between the first check valve and the second buffer tank through a concentrated liquid circulation pipe, the concentrated liquid circulation pipe is sequentially provided with a second stop valve and a second check valve in the direction from the third concentrated liquid delivery pipe to the first concentrated liquid delivery pipe, the first concentrated liquid delivery pipe between the second booster pump and the fourth regulating valve is connected with the inlet end of the second concentrated liquid delivery pipe, and the second concentrated liquid delivery pipe is provided with a sixth regulating valve.

[0009] Preferably, the liquid phase outlet end of the second centrifuge is connected with a first centrifugal liquid delivery pipe, the first centrifugal liquid delivery pipe is provided with a fifth buffer tank, the fifth buffer tank and the second concentration reactor are connected through a second centrifugal liquid delivery pipe, the second centrifugal liquid delivery pipe is sequentially provided with a fifth booster pump and a second liquid flow sensor in the direction from the fifth buffer tank to the second concentration reactor, the second centrifugal liquid delivery pipe between the fifth buffer tank and the fifth booster pump is provided with a third centrifugal liquid delivery pipe, the second centrifugal liquid delivery pipe between the third centrifugal liquid delivery pipe and the second liquid flow sensor and the third centrifugal liquid delivery pipe are respectively provided with an eighth regulating valve.

[0010] Preferably, the top of the cleaning tank is connected with the first centrifuge below, the third centrifuge is arranged above the cleaning tank, the inlet end of the third centrifuge and the bottom of the cleaning tank are connected through a cleaning delivery pipe, the cleaning delivery pipe is provided with a third stop valve, a fourth booster pump and a second online densimeter, the solid phase outlet end of the third centrifuge is provided with a first solid material delivery pipe and a second solid material delivery pipe, the third centrifuge and the cleaning tank are connected through the second solid material delivery pipe, the first solid material delivery pipe and the second solid material delivery pipe are respectively provided with a fourth stop valve, the first centrifuge and the first concentration reactor are connected through a fourth centrifugal liquid delivery pipe, the fourth centrifugal liquid delivery pipe is provided with a seventh buffer tank, and the liquid phase outlet end of the third centrifuge is connected with the seventh buffer tank.

[0011] Preferably, the gas phase outlet end of the second concentration reactor is sequentially connected with a third liquefied water delivery pipe and a sixth buffer tank, the third liquefied water delivery pipe is provided with a third heat exchanger, the sixth buffer tank and the cleaning tank are connected through a fourth liquefied water delivery pipe, the fourth liquefied water delivery pipe is provided with a fifth liquefied water delivery pipe, and the fourth liquefied water delivery pipe between the fifth liquefied water delivery pipe and the cleaning tank and the fifth liquefied water delivery pipe are respectively provided with a ninth regulating valve.

[0012] The wastewater treatment method of the plasticizer wastewater treatment device has the characteristics that it comprises the following steps:

[0013] S5: the acidification reactor receives the wastewater delivered by the first buffer tank and reaches a preset liquid level, then a predetermined amount of sulfuric acid is added to the acidification reactor to acidify the wastewater to form a strong acid environment; then continuous stirring is performed, and when stirring reaches a preset time, the wastewater is delivered to the first centrifuge for solid-liquid separation, the liquid phase component is delivered to the first concentration reactor through the liquid phase component outlet of the first centrifuge, and the solid phase component is discharged through the solid phase component outlet of the first centrifuge;

[0014] S6: the liquid entering the first concentration reactor can be started after reaching a preset liquid level, the first concentration reactor concentrates the liquid entering the first concentration reactor once to form an acidic concentrated liquid, and the acidic concentrated liquid is divided into two parts: one part is delivered to the third buffer tank, and the remaining part is delivered to the second buffer tank for temporary storage;

[0015] S7: sodium hydroxide lye is added to the second buffer tank until the value of the acidity meter on the second buffer tank is neutral, to form a neutral concentrated liquid; part of the neutral concentrated liquid is delivered to the electrolytic cell to remove the remaining organic matter contained in the neutral concentrated liquid by electrolysis, to form electrolysis residual liquid;

[0016] S8: the electrolysis residual liquid is delivered to the second concentration reactor for secondary concentration, to form secondary concentrated liquid;

[0017] S9: the secondary concentrated liquid is delivered to one of the crystallization tanks in a state of waiting for the secondary concentrated liquid, after the delivery is completed, crystal seeds are added to the crystallization tank to crystallize sodium sulfate, the crystallization tank is sufficiently placed to complete the crystallization process, to form sodium sulfate crystals and crystallization residual liquid, and then the sodium sulfate crystals are discharged from the solid phase outlet of the second centrifuge, and the crystallization residual liquid is discharged from the liquid phase outlet of the second centrifuge.

[0018] The present application has the following beneficial effects: first, the present application realizes separation and recovery of alcohol contained in the plasticizer wastewater as crude alcohol, effectively recovering alcohol raw materials for plasticizer production;

[0019] In addition, the organic acid contained in the distillation residual liquid is separated as a solid by step-by-step separation, the recovery of the organic acid reduces the material loss of the organic acid and reduces the content of the organic matter contained in the solid after concentration and crystallization, thereby reducing the hazardous waste level of the solid; and after separation of the alcohol phase and the organic acid, a small amount of organic matter is still contained in the residual liquid, the electrolytic cell is used to remove the organic matter contained in the residual liquid by electrolysis, so that the content of the organic matter in the residual liquid delivered to the second concentration reactor for secondary concentration is approximately zero; the content of the organic matter in the residual liquid is greatly reduced, so that the residual liquid is easier to handle.

[0020] Secondly, the present application forms secondary concentrated liquid by secondary concentration in the second concentration reactor and sends it to the crystallization tank to add seed crystals to crystallize sodium sulfate, realizing the recovery of sodium sulfate.

[0021] Finally, the present application forms acid concentrated liquid by primary concentration in the first concentration reactor, and sends part of the formed acid concentrated liquid to the third buffer tank for temporary storage, as one of the sources of acid medium in the acidification reactor, saving the material consumption for treating plasticizer wastewater.

[0022] The present application has the advantages of simple structure, convenient operation, ingenious design, greatly improved work efficiency, good social and economic benefits, and is a product easy to popularize and use. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic diagram of the present application.

[0024] Figure 2 is Figure 1 is a partial enlarged schematic diagram of detail A. DETAILED DESCRIPTION

[0025] Example 1: as Figure 1 , 2As shown, a plasticizer wastewater treatment device comprises a wastewater delivery pipe 1, a rectifying tower is communicated with the outlet end of the wastewater delivery pipe 1, a reboiling circulation pipe 2 is arranged on the rectifying tower, the rectifying tower comprises a tower body 25, a first packing layer 26 and a second packing layer 27 are sequentially arranged in the tower body 25 from top to bottom, the tower body 25 between the first packing layer 26 and the second packing layer 27 is communicated with the wastewater delivery pipe 1, a cold source channel of a first heat exchanger 28 is arranged on the wastewater delivery pipe 1, the inlet end of a heat source channel of the first heat exchanger 28 is communicated with the top end of the tower body 25, the outlet end of the heat source channel of the first heat exchanger 28 is communicated with a gas-liquid separation tank 29, the liquid phase outlet end of the gas-liquid separation tank 29 is communicated with the tower body 25 above the first packing layer 26 through a crude alcohol reflux pipe 30, a second adjusting valve 31 is arranged on the crude alcohol reflux pipe 30, a crude alcohol delivery pipe 32 is arranged on the crude alcohol reflux pipe 30 between the second adjusting valve 31 and the gas-liquid separation tank 29, and a third adjusting valve 33 is arranged on the crude alcohol delivery pipe 32. The inlet end of the reboiling circulation pipe 2 is located at the bottom end of the tower body 25, and the outlet end of the reboiling circulation pipe 2 is located on the tower body 25 between the inlet end of the reboiling circulation pipe 2 and the second packing layer 27; a first stop valve 3, a first booster pump 4, a reboiler 5, a temperature sensor 74 and a first online densimeter 6 are sequentially arranged on the reboiling circulation pipe 2 along the direction from the inlet end of the reboiling circulation pipe 2 to the outlet end of the reboiling circulation pipe 2, the inlet end of a first buffer tank 7 is communicated with the reboiling circulation pipe 2 between the first booster pump 4 and the reboiler 5, the reboiling circulation pipe 2 and the first buffer tank 7 are communicated through a fifth concentrated liquid delivery pipe 76, the tenth adjusting valve 75 is arranged on the reboiling circulation pipe 2 between the fifth concentrated liquid delivery pipe 76 and the reboiler 5 and on the fifth concentrated liquid delivery pipe 76 respectively; the outlet end of the first buffer tank 7 is communicated with an acidification reaction kettle 8, the acidification reaction kettle 8 and the first buffer tank 7 are communicated through a sixth concentrated liquid delivery pipe 77, and a sixth booster pump 78 is arranged on the sixth concentrated liquid delivery pipe 77; the inlet end of a first centrifuge 9 is communicated with the lower part of the acidification reaction kettle 8, the liquid phase outlet end of the first centrifuge 9 is communicated with a first concentration reaction kettle 10, the outlet end of the first concentration reaction kettle 10 is communicated with a second buffer tank 11, the second buffer tank 11 and the first concentration reaction kettle 10 are communicated through a first concentrated liquid delivery pipe 12, a second concentrated liquid delivery pipe 13 is arranged on the first concentrated liquid delivery pipe 12, the outlet end of the second concentrated liquid delivery pipe 13 is communicated with a third buffer tank 14, the third buffer tank 14 and the acidification reaction kettle 8 are communicated, and the outlet end of the second buffer tank 11 is sequentially communicated with an electrolytic cell 15, a second concentration reaction kettle 16, a crystallization tank 17 and a second centrifuge 18.

[0026] The acidification reaction kettle 8, the first concentration reaction kettle 10 and the second concentration reaction kettle 16 are respectively provided with a pressure sensor 72, a temperature sensor 74 and a liquid level sensor 73. The acidification reaction kettle 8, the first concentration reaction kettle 10 and the second buffer tank 11 are respectively provided with an acidity meter 24.

[0027] The number of acidification reactors 8, second concentration reactors 16 and crystallization tanks 17 is several, and the several acidification reactors 8 are connected in parallel, the several second concentration reactors 16 are connected in parallel, and the several crystallization tanks 17 are connected in parallel.

[0028] Before the formal driving operation stage, a pre-operation process is needed, which is divided into two stages in the case, namely the first pre-operation process stage and the second pre-operation process stage. The first pre-operation process stage includes the following steps: S1: the wastewater generated in the plasticizer production system is transported from the wastewater conveying pipe 1 to the inner cavity of the tower body 25 between the first filler layer 26 and the second filler layer 27 through the cold source channel of the first heat exchanger 28, and flows to the bottom of the tower body 25 through the second filler layer 27 due to gravity.

[0029] S2: the medium at the bottom of the tower body 25 enters the inlet end of the reboiling circulation pipe 2, is pressurized by the first booster pump 4, and then enters the wastewater in the reboiling circulation pipe 2, which moves along the direction from the inlet end of the reboiling circulation pipe 2 to the outlet end of the reboiling circulation pipe 2, during which it is heated by the reboiler 5 and then fed back to the bottom of the tower body 25 to form a heat source after the mixed liquid density and temperature sensor 74 feeds back the temperature. A large amount of alcohol components and water components form a gas phase part flowing along the second filler layer 27 to the top of the tower body 25, during which the rising steam and the wastewater in the inner cavity of the tower body 25 between the first filler layer 26 and the second filler layer 27 perform countercurrent heat exchange. The rising steam part is cooled and flows back to the wastewater at the bottom, and the alcohol component part contained in the wastewater is evaporated and flows with the rising steam through the first filler layer 26 to the tower body 25; the steam is a gaseous mixture of alcohol and water.

[0030] S3: The steam enters the first heat exchanger 28 through the tower body 25 and exchanges heat with the wastewater transported by the wastewater transport pipe 1 entering the cold source channel of the first heat exchanger 28. The steam passing through the hot source channel of the first heat exchanger 28 is cooled, the alcohol phase and the water phase are liquefied, and a small amount of non-condensable gas is cooled; the wastewater transported by the wastewater transport pipe 1 passing through the cold source channel of the first heat exchanger 28 is heated and then transported into the inner cavity of the tower body 25. The gaseous phase components after being liquefied enter the gas-liquid separation tank 29, the non-condensable gas is discharged through the top of the gas-liquid separation tank 29 and sent to the industrial flare for combustion treatment, the liquid phase components are liquid mixtures of alcohol and water, and the crude alcohol is enriched at the bottom of the gas-liquid separation tank 29; a part of the crude alcohol flows back to the inner cavity of the tower body 25 above the first filler layer 26 as another cold source and continuously descends under the action of gravity and countercurrently exchanges heat with the steam continuously rising through the first filler layer 26, the water phase components in the steam are liquefied and then descend to the bottom of the tower body 25, the alcohol phase in the liquid crude alcohol is continuously evaporated and rises, and the water phase continuously descends along the first filler layer 26 to the bottom of the tower body 25. Another part of the crude alcohol is transported to the crude alcohol rectification section through the crude alcohol transport pipe 32 for rectification of the crude alcohol, and then the alcohol phase is recovered to save costs. When the value fed back by the first online densimeter 6 is continuously stable in the preset range, the first pre-operation process stage ends.

[0031] The purpose of the first pre-running process is to form a liquid residue with low alcohol content at the bottom of the column body 25. On the basis of the first stage pre-running process, the second stage pre-running process is carried out. The second pre-running process stage includes the S1 step to the S3 step of the first pre-running process stage, but the S2 step of the second pre-running process stage is different from the S2 step of the first pre-running process stage. The wastewater entering the reboiling circulation pipe 2 no longer moves along the direction from the inlet end of the reboiling circulation pipe 2 to the outlet end of the reboiling circulation pipe 2. Instead, part of the wastewater entering the reboiling circulation pipe 2 moves along the direction from the inlet end of the reboiling circulation pipe 2 to the outlet end of the reboiling circulation pipe 2. This part of the wastewater is heated by the reboiler 5, fed back to the bottom of the column body 25 after being fed back to the column body 25, and forms a heat source. The other part of the wastewater is transported to the first buffer tank 7 through the fifth concentrated liquid delivery pipe 76. The distribution ratio of the part of the wastewater fed back to the column body 25 and the part of the wastewater transported to the first buffer tank 7 is comprehensively adjusted by adjusting the opening degree of the tenth adjusting valve 75 installed on the reboiling circulation pipe 2 between the fifth concentrated liquid delivery pipe 76 and the reboiler 5 and the opening degree of the tenth adjusting valve 75 installed on the fifth concentrated liquid delivery pipe 76. Since the liquid residue with low alcohol content is formed at the bottom of the column body 25 in the first pre-running process, the alcohol phase contained in the wastewater continuously transported to the inner cavity of the column body 25 through the wastewater delivery pipe 1 is largely evaporated in the second filler layer 27 during the countercurrent heat exchange with the steam generated from the bottom of the column body 25, and falls to the residue at the bottom of the column body 25 and the liquid fed back to the bottom of the column body 25 to form the wastewater entering the reboiling circulation pipe 2. The alcohol phase content of this part of the wastewater is low.

[0032] On the basis of the first stage pre-running process, the second stage pre-running process adds the following steps after the S3 step. S4: The fifth concentrated liquid delivery pipe 76 continuously enters the first buffer tank 7 for temporary storage. The first buffer tank 7 is transported to the acidification reactor 8 according to the demand of the corresponding acidification reactor 8, and is transported to the acidification reactor 8 under the pressure of the sixth booster pump 78 through the sixth concentrated liquid delivery pipe 77 to the preset liquid level of the acidification reactor 8.

[0033] S5: the acidification reactor 8 receives the wastewater from the first buffer tank 7 and reaches a preset liquid level, and then a predetermined amount of sulfuric acid is added to the acidification reactor 8 to acidify the wastewater to form a strong acid environment, and the PH value is not greater than 2; then continuous stirring is carried out, in the process, after the acidification of the wastewater, the organic acid component in the wastewater continuously precipitates to form a suspension liquid, and when the stirring reaches a preset time, it is transported to the first centrifugal machine 9 for solid-liquid separation, the liquid phase component is transported to the first concentration reactor 10 through the liquid phase component outlet of the first centrifugal machine 9, and the solid phase component is discharged through the solid phase component outlet of the first centrifugal machine 9; in this step, the organic acid component forms a solid phase which is separated and discharged through the solid phase component outlet of the first centrifugal machine 9 and then recycled.

[0034] S6: the liquid entering the first concentration reactor 10 reaches a preset liquid level and can be started, the first concentration reactor 10 concentrates the liquid entering the first concentration reactor 10 once to form an acidic concentrated liquid, and the acidic concentrated liquid is divided into two parts: one part is transported to the third buffer tank 14, and the remaining part is transported to the second buffer tank 11 for temporary storage.

[0035] S7: sodium hydroxide lye is added to the second buffer tank 11 until the value of the acidity meter 24 on the second buffer tank 11 is neutral, forming a neutral concentrated liquid; part of the neutral concentrated liquid is transported to the electrolytic cell 15 for electrolysis to remove the remaining organic matter contained therein, forming an electrolysis residual liquid.

[0036] S8: the electrolysis residual liquid is transported to the second concentration reactor 16 for secondary concentration to form a secondary concentrated liquid.

[0037] S9: the secondary concentrated liquid is transported to one of the crystallization tanks 17 which is in a standby state for receiving the secondary concentrated liquid, after the transportation is completed, crystal seeds are added to the crystallization tank 17 for sodium sulfate crystallization, and the crystallization process is completed after sufficient standing, forming sodium sulfate crystals and a crystallization residual liquid, which is then sent to the second centrifugal machine 18 for solid-liquid separation, the sodium sulfate crystals are discharged from the solid phase outlet of the second centrifugal machine 18, and the crystallization residual liquid is discharged from the liquid phase outlet of the second centrifugal machine 18.

[0038] After the above steps are completed and the third buffer tank 14 reaches a preset liquid level, the second pre-operation process stage is completed, and the production steps of the formal start-up operation stage include steps S1 to S9 of the second pre-operation stage, but the step S5 of the formal start-up operation stage is different from the step S5 of the second pre-operation stage, the difference lies in that in the step S5 of the formal start-up operation stage, the acidic medium in the acidification reactor 8 is partly derived from externally added sulfuric acid and partly derived from the concentrated acidic concentrated liquid stored in the third buffer tank 14.

[0039] Example 1 demonstrates the successful separation and recovery of the alcohol phase from plasticizer wastewater as crude alcohol, effectively recovering the alcohol raw material used in plasticizer production. Furthermore, through stepwise separation, organic acids as solids are separated from the distillation residue. This recovery reduces material loss of organic acids and lowers the hazardous waste level of the solids after concentration and crystallization. Even after separating the alcohol phase and organic acids, the residue still contains a small amount of organic matter. This residual organic matter is removed by electrolysis in electrolytic cell 15 before being fed into the second concentration reactor. The organic matter content in the residual liquid after secondary concentration in reactor 16 is approximately zero, which greatly reduces the organic matter content in the residual liquid and makes it easier to treat. Then, after secondary concentration in the second concentration reactor 16, a crystallized residual liquid is formed and transported to the crystallization tank 17 to add seed crystals for sodium sulfate crystallization, thus realizing the recovery of sodium sulfate. Finally, the liquid is concentrated once in the first concentration reactor 10 to form an acidic concentrate, and a portion of the formed acidic concentrate is transported to the third buffer tank 14 for temporary storage, serving as one of the sources of acidic medium in the acidification reactor 8, thus saving material consumption in the treatment of plasticizer wastewater.

[0040] Example 2, as Figure 1 and Figure 2 As shown, unlike Example 1, Example 2, based on Example 1, includes a first liquefied water delivery pipe 19 on the distillation column. The first liquefied water delivery pipe 19 has a heat source channel for a second heat exchanger 20. An alkali preparation tank 21 is located at the outlet end of the first liquefied water delivery pipe 19. A second liquefied water delivery pipe 22 is connected between the alkali preparation tank 21 and the second heat exchanger 20. First regulating valves 23 are installed on both the first liquefied water delivery pipe 19 and the second liquefied water delivery pipe 22. The bottom of the alkali preparation tank 21 is connected to the top of the second buffer tank 11. A first regulating valve 23 is also installed on the connecting pipe between the alkali preparation tank 21 and the second buffer tank 11. The alkali preparation tank 21 is equipped with a stirring device and a pH meter 24.

[0041] The high concentration water vapor produced in the process of rectifying the wastewater produced in the plasticizer production system in steps S1 to S3 in Example 1 is sent out through the first liquefied water delivery pipe 19, and is exchanged with the cold source continuously sent through the heat source channel of the second heat exchanger 20 and the cold source channel of the second heat exchanger 20 in Example 2. The water vapor is liquefied through the heat source channel of the second heat exchanger 20 to form liquefied water, which is discharged from the outlet end of the heat source channel of the second heat exchanger 20 and continuously moves along the first liquefied water delivery pipe 19 towards the alkali preparation tank 21. Part of the liquefied water enters the alkali preparation tank 21, and the other part of the liquefied water is delivered to the biochemical treatment device through the second liquefied water delivery pipe 22 for treatment.

[0042] The liquefied water entering the alkali preparation tank 21 is used as a solvent for preparing alkali. A predetermined amount of sodium hydroxide is added according to the liquid level feedback of the alkali preparation tank 21 to form a sodium hydroxide solution with a predetermined concentration. The acidity value of the sodium hydroxide solution is fed back by the acidity meter 24 installed on the alkali preparation tank 21, which serves as the source of the sodium hydroxide alkali required by the second buffer tank 11 in step S7 in Example 1.

[0043] By comparing Example 2 with Example 1, the liquefied water formed by liquefying the water vapor discharged from the rectifying tower in Example 2 is used as the source of the sodium hydroxide alkali required by the second buffer tank 11 in step S7 in Example 1. The liquefied water formed by liquefying the water vapor discharged from the rectifying tower still contains a small amount of alcohol phase components, which are used as the source of the sodium hydroxide alkali required by the second buffer tank 11. The sodium hydroxide alkali provided by the second buffer tank 11 is neutral, and after forming a neutral concentrated solution, it is delivered to the electrolytic cell 15 for electrolysis. The additional alcohol phase components carried by the solvent will decompose into inorganic components after the electrolysis process in the electrolytic cell 15. Although part of the electricity is consumed, the addition of external liquid phase medium in the wastewater treatment process is reduced, and the total amount of wastewater treated is reduced.

[0044] Example 3, as shown in Figure 1 and Figure 2 The difference between Example 4 and Example 1 is that the fourth concentrated solution delivery pipe 44 is connected between the third buffer tank 14 and the acidification reaction kettle 8 in Example 4 based on Example 1. The sulfuric acid storage tank 45 is connected above the acidification reaction kettle 8. The sulfuric acid storage tank 45 and the acidification reaction kettle 8 are connected through the sulfuric acid delivery pipe 46. The first liquid flow sensor 47 and the seventh adjusting valve 48 are respectively arranged on the sulfuric acid delivery pipe 46 and the fourth concentrated solution delivery pipe 44.

[0045] In addition, the difference between the embodiment 1 and the embodiment 2 is that, in the formal operation stage, the acid medium in the acidification reactor 8 is provided by the sulfuric acid storage tank 45 and is transported through the sulfuric acid delivery pipe 46, and the volume of the sulfuric acid transported to the acidification reactor 8 through the sulfuric acid delivery pipe 46 is fed back by the first liquid flow sensor 47 installed on the sulfuric acid delivery pipe 46; the acid concentrated solution from the third buffer tank 14 and transported to the acidification reactor 8 is transported through the fourth concentrated solution delivery pipe 44, and the volume of the acid concentrated solution transported to the acidification reactor 8 through the fourth concentrated solution delivery pipe 44 is fed back by the first liquid flow sensor 47 installed on the fourth concentrated solution delivery pipe 44.

[0046] By comparing the embodiment 3 with the embodiment 1, the embodiment 3 is provided with the sulfuric acid storage tank 45, the sulfuric acid delivery pipe 46 and the first liquid flow sensor 47 installed on the sulfuric acid delivery pipe 46 to facilitate the feedback of the volume of the sulfuric acid transported to the acidification reactor 8 by the sulfuric acid storage tank 45; the fourth concentrated solution delivery pipe 44 and the first liquid flow sensor 47 installed on the fourth concentrated solution delivery pipe 44 to facilitate the feedback of the volume of the acid concentrated solution transported to the acidification reactor 8 by the third buffer tank 14.

[0047] The embodiment 4, as shown in Figure 1 and Figure 2 The difference between the embodiment 3 and the embodiment 4 is that, in the embodiment 4, the second booster pump 34, the fourth regulating valve 35 and the first one-way valve 36 are sequentially arranged along the first concentrated solution delivery pipe 12 from the first concentrated solution reactor 10 to the second buffer tank 11, the electrolytic tank 15 and the second buffer tank 11 are connected through the third concentrated solution delivery pipe 37, the third booster pump 38 and the fifth regulating valve 39 are sequentially arranged along the third concentrated solution delivery pipe 37 from the second buffer tank 11 to the electrolytic tank 15, the third concentrated solution delivery pipe 37 between the third booster pump 38 and the fourth regulating valve 35 and the first concentrated solution delivery pipe 12 between the first one-way valve 36 and the second buffer tank 11 are connected through the concentrated solution circulation pipe 40, the second stop valve 41 and the second one-way valve 42 are sequentially arranged along the concentrated solution circulation pipe 40 from the third concentrated solution delivery pipe 37 to the first concentrated solution delivery pipe 12, the first concentrated solution delivery pipe 12 between the second booster pump 34 and the fourth regulating valve 35 is connected to the inlet end of the second concentrated solution delivery pipe 13, and the sixth regulating valve 43 is arranged on the second concentrated solution delivery pipe 13.

[0048] The difference between the embodiment 3 and the embodiment 4 is that the step S6: the first concentration reactor 10 concentrates the liquid entering into the first concentration reactor 10 once to form the acidic concentrated liquid, and the acidic concentrated liquid is divided into two parts: one part is delivered to the third buffer tank 14, and the part of the acidic concentrated liquid delivered to the third buffer tank 14 is delivered through the first concentrated liquid delivery pipe 12 and the second concentrated liquid delivery pipe 13, and is pressurized by the second booster pump 34 on the first concentrated liquid delivery pipe 12; the remaining part is delivered to the second buffer tank 11 for temporary storage, and the part delivered to the second buffer tank 11 is pressurized by the second booster pump 34 and then delivered through the first concentrated liquid delivery pipe 12; the ratio between the acidic concentrated liquid delivered to the second buffer tank 11 and the acidic concentrated liquid delivered to the third buffer tank 14 is comprehensively adjusted by adjusting the opening of the fourth adjusting valve 35 installed on the first concentrated liquid delivery pipe 12 and adjusting the opening of the sixth adjusting valve 43 installed on the second concentrated liquid delivery pipe 13. It is worth mentioning that the liquid phase component delivered to the first concentration reactor 10 from the first centrifuge 9 in the step S5 of the embodiment 3 still contains part of the organic acid, and part of the organic acid will precipitate to form solid precipitate during the concentration of the liquid phase component in the first concentration reactor 10, that is, the acidic concentrated liquid delivered to the third buffer tank 14 and the second buffer tank 11 by the first concentration reactor 10 is a suspension liquid; the organic acid precipitated in the acidic concentrated liquid delivered to the third buffer tank 14 and the acidification reactor 8 is collected again during the acidification process, thereby improving the recovery rate of the organic acid. Further, the inlet end of the third concentrated liquid delivery pipe 37 is located above the bottom end of the second buffer tank 11, and a blowdown pipe is arranged at the bottom end of the second buffer tank 11, and a blowdown stop valve is arranged on the blowdown pipe. The solid form organic acid contained in the acidic concentrated liquid delivered to the second buffer tank 11 is enriched at the bottom of the inner cavity of the second buffer tank 11, and the blowdown stop valve is opened regularly to discharge part of the acidic concentrated liquid containing the organic acid from the second buffer tank 11 by the blowdown pipe, so as to separate the organic acid precipitate and maximize the recovery of the organic acid, and reduce the amount of organic matter decomposed by the electrolytic cell 15.

[0049] In addition, different from the embodiment 3, in the step S7, the sodium hydroxide lye is added into the second buffer tank 11 until the acidity meter 24 on the second buffer tank 11 feeds back a neutral value, and in the process of forming the neutral concentrated solution, the third booster pump 38 and the second stop valve 41 are opened and the fifth regulating valve 39 is closed during the process of the second buffer tank 11 receiving the sodium hydroxide lye, and the third booster pump 38 boosts the acidic concentrated solution entering into the concentrated solution circulation pipe 40 through the third concentrated solution delivery pipe 37, so that the acidic concentrated solution temporarily stored in the second buffer tank 11 sequentially passes through the third concentrated solution delivery pipe 37 and the concentrated solution circulation pipe 40, and finally returns to the second buffer tank 11 to form a circulation.

[0050] By comparing the embodiment 4 with the embodiment 3, in the embodiment 3, the first concentrated solution delivery pipe 12 and the second concentrated solution delivery pipe 13 are arranged, the fourth regulating valve 35 is arranged on the first concentrated solution delivery pipe 12, and the sixth regulating valve 43 is arranged on the second concentrated solution delivery pipe 13, so as to facilitate the adjustment of the proportion of the acidic concentrated solution delivered to the second buffer tank 11 and the third buffer tank 14; in addition, the concentrated solution circulation pipe 40 and the third concentrated solution delivery pipe 37 are arranged, and the third booster pump 38 is arranged on the third concentrated solution delivery pipe 37, and the flow direction function is provided by the first one-way valve 36 arranged on the first concentrated solution delivery pipe 12 and the second one-way valve 42 arranged on the concentrated solution circulation pipe 40. During the process of the second buffer tank 11 receiving the sodium hydroxide lye, the acidic concentrated solution in the second buffer tank 11 returns to the second buffer tank 11 through the concentrated solution circulation pipe 40 to form a circulation after the third booster pump 38 is driven, so as to promote the quick mixing of the acidic concentrated solution in the second buffer tank 11 and the sodium hydroxide lye entering into the second buffer tank 11, thereby reducing the technical problem of the sodium hydroxide lye addition excess.

[0051] As shown in the embodiment 5, Figure 1 and Figure 2 different from the embodiment 1, the embodiment 5 is based on the embodiment 1, and the first centrifugal liquid delivery pipe 49 is communicated with the liquid phase outlet end of the second centrifugal machine 18, the fifth buffer tank 50 is arranged on the first centrifugal liquid delivery pipe 49, the second centrifugal liquid delivery pipe 51 is communicated with the fifth buffer tank 50 and the second concentrated reaction kettle 16, the fifth booster pump 52 and the second liquid flow sensor 53 are sequentially arranged on the second centrifugal liquid delivery pipe 51 along the direction from the fifth buffer tank 50 to the second concentrated reaction kettle 16, the third centrifugal liquid delivery pipe 54 is arranged on the second centrifugal liquid delivery pipe 51 between the fifth buffer tank 50 and the fifth booster pump 52, and the eighth regulating valve 55 is arranged on the second centrifugal liquid delivery pipe 51 between the third centrifugal liquid delivery pipe 54 and the second liquid flow sensor 53 and on the third centrifugal liquid delivery pipe 54 respectively.

[0052] In addition, the difference between the embodiment 1 and the embodiment 2 is that the post-crystallization residual liquid is discharged from the liquid phase outlet of the second centrifugal machine 18, and then is sent to the fifth buffer tank 50 for temporary storage; a part of the post-crystallization residual liquid in the fifth buffer tank 50 is discharged to the drying furnace through the third centrifugal liquid conveying pipe 54 for drying and collecting residual inorganic solid, and another part is sent to the second concentration reaction kettle 16 through the second centrifugal liquid conveying pipe 51 to mix with the post-electrolysis residual liquid in the second concentration reaction kettle 16, for secondary concentration to form secondary concentrated liquid. In step S9, the secondary concentrated liquid is sent to the crystallization tank 17 to add crystal seeds for crystallization.

[0053] By comparing the embodiment 5 with the embodiment 1, the embodiment 5 re-sends a part of the post-crystallization residual liquid to the second concentration reaction kettle 16, and mixes with the post-electrolysis residual liquid in the second concentration reaction kettle 16 for secondary concentration to form secondary concentrated liquid, and then sends the secondary concentrated liquid to the crystallization tank 17 to add crystal seeds for crystallization. Since the post-crystallization residual liquid discharged from the liquid phase outlet of the second centrifugal machine 18 contains high-concentration sodium sulfate solute, the above operation method improves the recovery rate of sodium sulfate.

[0054] The embodiment 6, as shown in Figure 1 and Figure 2 The difference between the embodiment 1 and the embodiment 6 is that the embodiment 6 is based on the embodiment 1, and the top of the cleaning tank 59 is communicated with the bottom of the first centrifugal machine 9, the cleaning tank 59 is provided with a stirring device, the top of the cleaning tank 59 is provided with the third centrifugal machine 60, the inlet end of the third centrifugal machine 60 is communicated with the bottom of the cleaning tank 59 through the cleaning conveying pipe 61, the cleaning conveying pipe 61 is provided with the third stop valve 62, the fourth booster pump 63 and the second online density meter 64, the solid phase outlet end of the third centrifugal machine 60 is provided with the first solid conveying pipe 65 and the second solid conveying pipe 66, the third centrifugal machine 60 and the cleaning tank 59 are communicated through the second solid conveying pipe 66, the first solid conveying pipe 65 and the second solid conveying pipe 66 are respectively provided with the fourth stop valve 67, the first centrifugal machine 9 and the first concentration reaction kettle 10 are communicated through the fourth centrifugal liquid conveying pipe 79, the fourth centrifugal liquid conveying pipe 79 is provided with the seventh buffer tank 71, the liquid phase outlet end of the third centrifugal machine 60 is communicated with the seventh buffer tank 71. The gas phase outlet end of the second concentration reaction kettle 16 is sequentially communicated with the third liquefied water conveying pipe 56 and the sixth buffer tank 57, the third liquefied water conveying pipe 56 is provided with the third heat exchanger 58, the sixth buffer tank 57 and the cleaning tank 59 are communicated through the fourth liquefied water conveying pipe 68, the fourth liquefied water conveying pipe 68 is provided with the fifth liquefied water conveying pipe 69, the fourth liquefied water conveying pipe 68 and the fifth liquefied water conveying pipe 69 between the fifth liquefied water conveying pipe 69 and the cleaning tank 59 are respectively provided with the ninth regulating valve 70.

[0055] The solid phase component in step S5 is discharged from the solid phase component outlet of the first centrifuge 9, and is mainly composed of organic acid in solid form, with a small amount of impurities. The solid phase component is then transported to the cleaning tank 59 for temporary storage.

[0056] In addition, the steam generated in the second concentration reaction kettle 16 in step S8 is fed into the second concentration reaction kettle 16 for secondary concentration. The electrolyte after the secondary concentration is free of organic matter, and the steam generated in the secondary concentration is mainly pure water vapor. The steam is liquefied by heat exchange with the continuous cold source in the heat source channel of the third heat exchanger 58 and the cold source channel of the third heat exchanger 58, and forms liquefied water. The liquefied water is then transported to the sixth buffer tank 57 for temporary storage. The liquefied water in the sixth buffer tank 57 is mixed with the solid organic acid in the cleaning tank 59 under the driving of the stirring device installed in the cleaning tank 59, to replace the impurities on the surface of the solid organic acid. Then, the suspension is transported to the third centrifuge 60 for solid-liquid separation, and the liquid phase component is transported to the seventh buffer tank 71. The solid phase component is transported back to the cleaning tank 59 through the second solid material conveying pipe 66, and is cleaned again with the liquefied water in the sixth buffer tank 57. The above process is repeated multiple times until the value of the second on-line density meter 64 on the cleaning conveying pipe 61 reaches the preset range, and then the solid-liquid separation is performed for the last time in the third centrifuge 60. The liquid phase component is transported to the seventh buffer tank 71, and the solid phase component after cleaning is discharged through the first solid material conveying pipe 65 for collection.

[0057] By comparing example 6 with example 1, the solid organic acid separated in example 6 is repeatedly cleaned with the relatively pure water vapor generated in the wastewater treatment process by setting the cleaning tank 59, the third centrifuge 60, the sixth buffer tank 57, the third liquefied water conveying pipe 56, the fourth liquefied water conveying pipe 68, and the fifth liquefied water conveying pipe 69. The liquid after repeated cleaning contains part of the organic matter, which is then decomposed in the electrolytic tank 15. No additional wastewater is generated in the cleaning process, which needs to be treated by other systems. In addition, when the water level in the sixth buffer tank 57 exceeds the warning level, the liquefied water can be directly discharged through the fifth liquefied water conveying pipe 69, and the amount of discharge is controlled by the ninth adjusting valve 70 installed on the fifth liquefied water conveying pipe 69.

[0058] Example 7: As Figure 1 and Figure 2The difference between the embodiment 1 is that: the embodiment is with the phthalic acid di-octyl ester wastewater as an example, the anhydride is phthalic anhydride, in the embodiment, the wastewater is added into the acidification reactor 8 to form the phthalic acid; the solubility of the phthalic acid is 7g / L at 25℃, in the S5 step of the formal operation stage, the amount of the acid medium of the sulfuric acid and the acid concentrated solution in the acidification reactor 8 is not the more the better. The following formula one should be satisfied:

[0059] That is:

[0060] Wherein, A1 is the parameter of the wastewater containing organic acid which is not acidified in the acidification reactor 8 and is fed back by the acidity meter 24 installed on the acidification reactor 8;10 -A2 is the concentration of H+ when the concentrated sulfuric acid stored in the sulfuric acid storage tank 45 is completely hydrolyzed;10 -A3 is the concentration of H+ when the acid liquid concentrated by the first concentration reactor 10 and stored in the third buffer tank 14 is completely hydrolyzed; A4 is the parameter of the wastewater acidified in the acidification reactor 8 and fed back by the acidity meter 24 installed on the acidification reactor 8; is the concentration of phthalic anhydride in the wastewater containing organic acid which is not acidified in the acidification reactor 8; λ is the coefficient; V1 is the volume of the wastewater containing organic acid which is not acidified in the acidification reactor 8 and delivered to the acidification reactor 8 through the first buffer tank 7; V2 is the volume of the concentrated sulfuric acid delivered to the acidification reactor 8 through the sulfuric acid storage tank 45; V3 is the volume of the acid liquid concentrated and delivered to the acidification reactor 8 through the third buffer tank 14.

[0061] And the following formula two should be satisfied:

[0062]

[0063] Wherein, is the concentration of phthalic acid; K a1 is the coefficient of the first ionization of phthalic acid; is the concentration of phthalic monohydrogen root, C H + is the concentration of hydrogen ion.

[0064] Meanwhile, phthalic acid also has secondary ionization, but due to the excess of acid in the case, and the final solution is a strong acid medium, the secondary ionization of phthalic acid is extremely small, and can be ignored. When phthalic anhydride is formed, and in a strong acid medium, it can inhibit the hydrolysis degree of the generated phthalic acid, thereby reducing the solubility of phthalic acid in a strong acid medium, thereby obtaining more phthalic acid, but the total amount of concentrated sulfuric acid stored in the sulfuric acid storage tank 45 and the acid liquid stored in the third buffer tank 14 after being concentrated by the first concentration reactor 10 should be controlled within a reasonable range, that is, the following relationship is obtained by combining formula one and formula two:

[0065]

[0066] Wherein: A1 is the parameter fed back by the acidity meter 24 installed on the acidification reactor 8 for the wastewater containing organic acid which has not been acidified in the acidification reactor 8;10 -A2 is the concentration of H+ when H+ in the concentrated sulfuric acid stored in the sulfuric acid storage tank 45 is completely hydrolyzed;10 -A3 is the concentration of H+ when the acid liquid stored in the third buffer tank 14 after being concentrated by the first concentration reactor 10 is completely hydrolyzed; V1 is the volume of the wastewater containing organic acid which has not been acidified in the acidification reactor 8 delivered by the first buffer tank 7 to the acidification reactor 8; V2 is the volume of the concentrated sulfuric acid delivered by the sulfuric acid storage tank 45 to the acidification reactor 8; V3 is the volume of the acid liquid after being concentrated by the third buffer tank 14 delivered to the acidification reactor 8; is the concentration of phthalic acid; K a1 is the coefficient of the first ionization of phthalic acid; is the concentration of phthalic acid monohydrogen; is the concentration of phthalic anhydride in the wastewater containing organic acid which has not been acidified in the acidification reactor 8; λ is the coefficient.

[0067] And in the case, the total amount of concentrated sulfuric acid stored in the sulfuric acid storage tank 45 and the acid liquid stored in the third buffer tank 14 after being concentrated by the first concentration reactor 10 added to the acidification reactor 8 is not the more the better, and should meet a certain range, because when the concentration is lower than the preset concentration, continuing to add concentrated sulfuric acid and / or concentrated acid liquid will increase the total volume of the solution, that is, the phthalic acid that has been precipitated will be redissolved due to the increase in the total volume of the solution.

[0068] The above-described embodiments are only preferred embodiments of the present application and are not intended to limit the scope of the application. Any equivalent changes or modifications made in accordance with the structure, features and principles described in the patent scope of the present application should be included in the patent scope of the present application.

Claims

1. A plasticizer wastewater treatment apparatus characterized by comprising: The application relates to a wastewater treatment device, which comprises a wastewater conveying pipe (1), a rectifying tower communicated with the outlet end of the wastewater conveying pipe (1), a reboiling circulation pipe (2) arranged on the rectifying tower, a first stop valve (3), a first booster pump (4), a reboiler (5) and a first on-line densimeter (6) arranged on the reboiling circulation pipe (2) in sequence from the inlet end of the reboiling circulation pipe (2) to the outlet end of the reboiling circulation pipe (2), a first buffer tank (7) communicated with the reboiling circulation pipe (2) between the first booster pump (4) and the reboiler (5), an acidification reaction kettle (8) communicated with the outlet end of the first buffer tank (7), a first centrifuge (9) communicated with the liquid phase outlet end of the first centrifuge (9), a first concentration reaction kettle (10) communicated with the outlet end of the first concentration reaction kettle (10), a second buffer tank (11) communicated with the outlet end of the first concentration reaction kettle (10), a first concentrated liquid conveying pipe (12) connected between the second buffer tank (11) and the first concentration reaction kettle (10), a second concentrated liquid conveying pipe (13) arranged on the first concentrated liquid conveying pipe (12), a third buffer tank (14) communicated with the outlet end of the second concentrated liquid conveying pipe (13), the third buffer tank (14) and the acidification reaction kettle (8) being communicated, an electrolytic cell (15), a second concentration reaction kettle (16), a crystallization tank (17) and a second centrifuge (18) communicated with the outlet end of the second buffer tank (11) in sequence. The rectifying tower comprises a tower body (25), a first filler layer (26) and a second filler layer (27) arranged in the tower body (25) in sequence from top to bottom, the tower body (25) between the first filler layer (26) and the second filler layer (27) being communicated with the wastewater conveying pipe (1), a cold source channel of a first heat exchanger (28) arranged on the wastewater conveying pipe (1), the inlet end of a heat source channel of the first heat exchanger (28) being communicated with the top end of the tower body (25), the outlet end of the heat source channel of the first heat exchanger (28) being communicated with a gas-liquid separation tank (29), the liquid phase outlet end of the gas-liquid separation tank (29) and the tower body (25) above the first filler layer (26) being communicated through a crude alcohol reflux pipe (30), a second regulating valve (31) arranged on the crude alcohol reflux pipe (30), a crude alcohol conveying pipe (32) arranged on the crude alcohol reflux pipe (30) between the second regulating valve (31) and the gas-liquid separation tank (29), and a third regulating valve (33) arranged on the crude alcohol conveying pipe (32). The reboiling circulation pipe (2) between the first booster pump (4) and the reboiler (5) is communicated with the inlet end of the first buffer tank (7), the reboiling circulation pipe (2) and the first buffer tank (7) are communicated through a fifth concentrated liquid conveying pipe (76), the acidification reaction kettle (8) and the first buffer tank (7) are communicated through a sixth concentrated liquid conveying pipe (77), and a sixth booster pump (78) is arranged on the sixth concentrated liquid conveying pipe (77).

2. The plasticizer wastewater treatment apparatus according to claim 1, characterized by: The rectifying tower is provided with a first liquid water conveying pipe (19), a heat source channel of a second heat exchanger (20) is arranged on the first liquid water conveying pipe (19), an alkali liquor preparation tank (21) is arranged on the outlet end of the first liquid water conveying pipe (19), the first liquid water conveying pipe (19) between the alkali liquor preparation tank (21) and the second heat exchanger (20) is provided with a second liquid water conveying pipe (22), the first liquid water conveying pipe (19) between the second liquid water conveying pipe (22) and the alkali liquor preparation tank (21) and the second liquid water conveying pipe (22) are respectively provided with a first adjusting valve (23), the alkali liquor preparation tank (21) is provided with a stirring device, and the alkali liquor preparation tank (21), the acidification reaction kettle (8) and the first concentration reaction kettle (10) are respectively provided with an acidity meter (24) in correspondence.

3. The plasticizer wastewater treatment apparatus according to claim 1, characterized by: The first concentrated liquid conveying pipe (12) is sequentially provided with a second booster pump (34), a fourth adjusting valve (35) and a first one-way valve (36) in the direction from the first concentration reaction kettle (10) to the second buffer tank (11), the electrolytic cell (15) and the second buffer tank (11) are connected through a third concentrated liquid conveying pipe (37), the third concentrated liquid conveying pipe (37) is sequentially provided with a third booster pump (38) and a fifth adjusting valve (39) in the direction from the second buffer tank (11) to the electrolytic cell (15), the third concentrated liquid conveying pipe (37) between the third booster pump (38) and the fourth adjusting valve (35) and the first concentrated liquid conveying pipe (12) between the first one-way valve (36) and the second buffer tank (11) are connected through a concentrated liquid circulating pipe (40), the concentrated liquid circulating pipe (40) is sequentially provided with a second stop valve (41) and a second one-way valve (42) in the direction from the third concentrated liquid conveying pipe (37) to the first concentrated liquid conveying pipe (12), the first concentrated liquid conveying pipe (12) between the second booster pump (34) and the fourth adjusting valve (35) is connected with the inlet end of the second concentrated liquid conveying pipe (13), and the second concentrated liquid conveying pipe (13) is provided with a sixth adjusting valve (43).

4. The plasticizer wastewater treatment apparatus according to claim 1, characterized by: The liquid phase outlet end of the second centrifugal machine (18) is connected with a first centrifugal liquid conveying pipe (49), the first centrifugal liquid conveying pipe (49) is provided with a fifth buffer tank (50), the fifth buffer tank (50) and the second concentration reaction kettle (16) are connected through a second centrifugal liquid conveying pipe (51), the second centrifugal liquid conveying pipe (51) is sequentially provided with a fifth booster pump (52) and a second liquid flow sensor (53) in the direction from the fifth buffer tank (50) to the second concentration reaction kettle (16), the second centrifugal liquid conveying pipe (51) between the fifth buffer tank (50) and the fifth booster pump (52) is provided with a third centrifugal liquid conveying pipe (54), the second centrifugal liquid conveying pipe (51) between the third centrifugal liquid conveying pipe (54) and the second liquid flow sensor (53) and the third centrifugal liquid conveying pipe (54) are respectively provided with an eighth adjusting valve (55).

5. The plasticizer wastewater treatment apparatus according to claim 1, characterized by: The top of the cleaning tank (59) is communicated with the first centrifuge (9), the third centrifuge (60) is arranged above the cleaning tank (59), the inlet end of the third centrifuge (60) is communicated with the bottom of the cleaning tank (59) through the cleaning conveying pipe (61), the third cut-off valve (62), the fourth booster pump (63) and the second online density meter (64) are arranged on the cleaning conveying pipe (61), the solid phase outlet end of the third centrifuge (60) is provided with the first solid material conveying pipe (65) and the second solid material conveying pipe (66), the third centrifuge (60) and the cleaning tank (59) are communicated through the second solid material conveying pipe (66), the fourth cut-off valve (67) is arranged on the first solid material conveying pipe (65) and the second solid material conveying pipe (66) respectively, the first centrifuge (9) and the first concentration reaction kettle (10) are communicated through the fourth centrifugal liquid conveying pipe (79), the seventh buffer tank (71) is arranged on the fourth centrifugal liquid conveying pipe (79), and the liquid phase outlet end of the third centrifuge (60) is communicated with the seventh buffer tank (71).

6. The plasticizer wastewater treatment apparatus according to claim 5, characterized by: The gas phase outlet end of the second concentration reaction kettle (16) is sequentially communicated with the third liquefied water conveying pipe (56) and the sixth buffer tank (57), the third heat exchanger (58) is arranged on the third liquefied water conveying pipe (56), the sixth buffer tank (57) and the cleaning tank (59) are communicated through the fourth liquefied water conveying pipe (68), the fifth liquefied water conveying pipe (69) is arranged on the fourth liquefied water conveying pipe (68), and the fourth liquefied water conveying pipe (68) and the fifth liquefied water conveying pipe (69) between the fifth liquefied water conveying pipe (69) and the cleaning tank (59) are respectively provided with the ninth adjusting valve (70).

7. The plasticizer wastewater treatment method of the plasticizer wastewater treatment apparatus according to claim 1, characterized by, The method comprises the following steps: S1: the wastewater generated in the plasticizer production system is conveyed from the wastewater conveying pipe (1) to the cavity of the tower body (25) between the first packing layer (26) and the second packing layer (27) through the cold source channel of the first heat exchanger (28); S2: the medium at the bottom of the tower body (25) enters the inlet end of the reboiling circulation pipe (2) and is pressurized by the first booster pump (4), then the wastewater in the reboiling circulation pipe (2) moves from the inlet end to the outlet end of the reboiling circulation pipe (2), a large amount of alcohol components and water components form a gas phase part and flow along the second packing layer (27) to the top of the tower body (25), during which the rising steam and the wastewater in the cavity of the tower body (25) between the first packing layer (26) and the second packing layer (27) perform countercurrent heat exchange; S3: The steam enters the first heat exchanger (28) through the tower body (25) and exchanges heat with the wastewater transported by the wastewater transport pipe (1) entering the cold source channel of the first heat exchanger (28). The steam passing through the heat source channel of the first heat exchanger (28) is cooled, and the alcohol phase and water phase are liquefied. A small amount of non-condensable gas is cooled. The liquefied gas phase components enter the gas-liquid separation tank (29). The non-condensable gas is discharged through the top of the gas-liquid separation tank (29) and sent to the industrial flare for combustion treatment. The liquid phase components are a mixture of alcohol and water, and the crude alcohol is enriched at the bottom of the gas-liquid separation tank (29). Part of the crude alcohol is returned to the inner cavity of the tower body (25) above the first packing layer (26) as another cold source through the crude alcohol reflux pipe (30) and continuously descends under the action of gravity and exchanges heat with the steam continuously rising through the first packing layer (26) in countercurrent; S4: The fifth concentrated liquid transport pipe (76) continuously enters the first buffer tank (7) for temporary storage. The first buffer tank (7) transports the wastewater to the acidification reactor (8) through the sixth concentrated liquid transport pipe (77) under the pressure of the sixth booster pump (78) according to the requirements of the corresponding acidification reactor (8) to the preset liquid level of the acidification reactor (8); S5: The acidification reactor (8) receives the wastewater transported from the first buffer tank (7) and reaches the preset liquid level. Then, a predetermined amount of sulfuric acid is added to the acidification reactor (8) to acidify the wastewater and form a strong acid environment. Then, continuous stirring is performed. When the stirring reaches the preset time, it is transported to the first centrifuge (9) for solid-liquid separation. The liquid phase components are transported to the first concentration reactor (10) through the liquid phase component outlet of the first centrifuge (9), and the solid phase components are discharged through the solid phase component outlet of the first centrifuge (9); S6: The liquid entering the first concentration reactor (10) reaches the preset liquid level and can be started. The first concentration reactor (10) concentrates the liquid entering the first concentration reactor (10) once to form an acidic concentrated liquid. This part of the acidic concentrated liquid is divided into two parts: one part is transported to the third buffer tank (14), and the remaining part is transported to the second buffer tank (11) for temporary storage; S7: Sodium hydroxide lye is added to the second buffer tank (11) until the value of the pH meter (24) on the second buffer tank (11) is neutral, forming a neutral concentrated liquid. Part of the neutral concentrated liquid is transported to the electrolytic cell (15) for electrolysis to remove the remaining organic matter, forming an electrolysis residual liquid; S8: The electrolysis residual liquid is transported to the second concentration reactor (16) for secondary concentration, forming a secondary concentrated liquid; S9: The secondary concentrated liquid is transported to one of the crystallization tanks (17) waiting for the secondary concentrated liquid. After the transportation is completed, crystal seeds are added to the crystallization tank (17) to crystallize sodium sulfate. After sufficient standing, the crystallization process is completed, forming sodium sulfate crystals and a crystallization residual liquid. Then, it is sent to the second centrifuge (18) for solid-liquid separation. The sodium sulfate crystals are discharged from the solid phase outlet of the second centrifuge (18), and the crystallization residual liquid is discharged from the liquid phase outlet of the second centrifuge (18).

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