Sewage treatment device for indigo production

Abstract

The application discloses a kind of wastewater treatment devices for indigo production.Wastewater treatment devices for indigo production, including: auxiliary part, the auxiliary part side is connected with the distillation part of heating distillation of aniline in sewage, the distillation part side is connected with evaporation part, the evaporation part is used to remove water in sewage, the evaporation part side is installed crystallization part, the concentration of sewage after evaporation part processing is improved, part of salt is precipitated in crystallization part.The wastewater treatment device for indigo production provided by the application avoids the inhibitory effect of high-salt environment on microorganisms, uses pure physical separation means, first recycles aniline by heating distillation, then concentrates by negative pressure evaporation of water, and finally realizes fractional crystallization separation by using the difference in solubility of NaCl and Na2SO4 in water with temperature change.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a wastewater treatment device for indigo production. Background Technology

[0002] Indigo is a natural pigment extracted from plants of the Isatis tinctoria family. During its production, the wastewater generated contains higher concentrations of chloride ions, sulfate ions, and aniline compared to ordinary sewage, due to the fact that the mainstream modern indigo production process uses the potassium aniline acetate route.

[0003] The existing technology discloses a wastewater treatment device for indigo production, publication number CN213950909U, which includes a purification component comprising a sedimentation tank, an equalization tank, an acid-base neutralization tank, a coagulation sedimentation tank, an anaerobic tank, an aerobic biological treatment tank, a secondary sedimentation tank, a decolorization tank, a clear water tank, and a discharge tank. This invention, through the setup of the anaerobic and aerobic biological treatment tanks, allows for the organic cooperation of microorganisms under two different environmental conditions, achieving the functions of removing organic matter and denitrifying and dephosphorizing. Through a simple process flow design, the hydraulic retention time is not less than that of similar industries. The alternating operation of the anaerobic and aerobic tanks prevents the excessive proliferation of filamentous bacteria and sludge bulking. These features reduce the infrastructure costs of the treatment method, as well as the costs of electricity, operation, and maintenance, making this treatment method more readily available and widely applicable.

[0004] Existing technologies like the one described above are not ideal for treating wastewater from indigo production because the high concentration of ions in the wastewater is unfavorable for the survival of microorganisms.

[0005] Therefore, it is necessary to provide a wastewater treatment device for indigo production to solve the above-mentioned technical problems. Summary of the Invention

[0006] In view of the above situation and to overcome the defects of the prior art, the present invention provides a wastewater treatment device for indigo production that can treat wastewater by distillation and crystallization, and the treated products can be reused.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A wastewater treatment device for indigo production includes: an auxiliary section, a distillation section connected to one side of the auxiliary section for heating and distilling aniline in the wastewater, an evaporation section connected to one side of the distillation section for removing water from the wastewater, and a crystallization section installed on one side of the evaporation section. The concentration of the wastewater is increased after treatment by the evaporation section, and some salts are cooled and precipitated in the crystallization section.

[0009] The auxiliary unit includes a submersible pump, the output end of which is connected to an inlet pipe. Wastewater is drawn in from the input end of the submersible pump and discharged from the inlet pipe. The auxiliary unit also includes a condenser for cooling and liquefying gas, and a gas collecting pipe is installed on the condenser.

[0010] The distillation section includes a distillation chamber, and a gas collecting chamber is fixedly connected to one side of the distillation chamber. Both the distillation chamber and the gas collecting chamber are sealed spaces. The distillation chamber and the gas collecting chamber are connected through exhaust holes fixedly installed on their inner walls. A stirring assembly is installed in the distillation chamber. A gas collecting head with multiple air inlets is fixedly installed at the end of the gas collecting pipe. The gas collecting head is located in the gas collecting chamber.

[0011] The evaporation section includes an evaporation tank, which is under negative pressure. A heat pipe is fixedly installed on the inner wall of the evaporation tank. Hot waste gas is introduced into the heat pipe to heat the sewage in the evaporation tank to boiling point, causing the water in the sewage to evaporate. The evaporated water vapor enters the gas collection chamber and enters the condenser through the gas collection head to liquefy.

[0012] The crystallization section includes a crystallization chamber. A partition is horizontally fixed to the side wall of the crystallization chamber, dividing the crystallization chamber into two independent spaces, upper and lower. A filter assembly is installed on the partition. After the temperature of the wastewater in the upper crystallization chamber decreases and NaCl crystallizes, it passes through the filter assembly and enters the lower crystallization chamber to continue. As the temperature further decreases, Na2SO4 crystallizes out of the wastewater.

[0013] Preferably, the stirring assembly includes a first motor fixedly installed on the top of the distillation chamber, the output end of the first motor being fixedly installed on the upper end of a rotating shaft, the rotating shaft passing through the top of the distillation chamber and rotatably connected thereto, the lower end being located in the internal cavity of the distillation chamber, and multiple blades being fixedly installed at equal intervals around the rotating shaft.

[0014] Preferably, a slot for gas flow is provided on the common side wall of the distillation chamber and the gas collecting chamber, and a sealing door is rotatably installed at the slot. The sealing door can swing left and right to open in different directions. The sealing door is closed when the distillation chamber distills aniline, and the sealing door is opened when the evaporation section evaporates water vapor. The water vapor enters the gas collecting chamber through the slot at the sealing door.

[0015] Preferably, the top of the gas collection chamber and the evaporation tank are fixedly connected and sealed with a sealing cover.

[0016] Preferably, the evaporation tank is provided in two sets, and the bottom of the evaporation tank is conical, so that impurities in the sewage settle to the bottom of the evaporation tank.

[0017] Preferably, a debris removal assembly is installed at the upper end of the evaporation tank to remove floating debris and impurities on the surface of the evaporation tank. The debris removal assembly includes a second motor, with a second chain sleeved at the output end of the second motor. Two sets of driven gears are rotatably installed at the upper end of the evaporation tank, and a first chain is sleeved on the two sets of driven gears. The first chain rotates with the rotation of the driven gears. A scraper is fixedly installed on the first chain. When the scraper rotates to the lower spoke of the first chain, it scrapes off the floating debris on the surface of the sewage in the evaporation tank. The scraped debris enters the debris removal chamber.

[0018] Preferably, the impurity removal chamber is located between the evaporation tank and the crystallization chamber. A pipette is installed on the side wall of the impurity removal chamber, which connects the impurity removal chamber to the interior of the evaporation tank. The pipette is located at the upper end of the conical bottom of the evaporation tank. A gate is opened on the other side of the impurity removal chamber, which connects the impurity removal chamber to the crystallization chamber. A handwheel is provided at the upper end of the gate, and rotating the handwheel controls the opening and closing of the gate. A reflux pipe is also fixedly installed on the side wall of the evaporation tank. The water in the reflux pipe is transported to the distillation chamber by a reflux pump installed on it.

[0019] Preferably, the filtration assembly includes a control valve mounted on a partition, the control valve controlling the flow of wastewater from the upper crystallization chamber into the lower crystallization chamber, a filter screen at the lower end of the control valve, the filter screen being fixedly mounted on the lower end of the partition, and an outlet pipe installed on the side wall of the lower crystallization chamber.

[0020] A method for treating wastewater from indigo production, the method comprising:

[0021] S1: Wastewater is pumped into the inlet pipe by a submersible pump and transported to the distillation chamber. In the distillation chamber, the wastewater is heated by a heat pipe fixed inside and stirred by a paddle, causing aniline gas to be released and enter the gas collection chamber through the exhaust port. Then, the aniline gas is absorbed by the gas collection head and enters the gas collection pipe, where it is liquefied and recovered by the condenser.

[0022] S2: Wastewater that has been treated to remove aniline gas is pumped into the evaporation tank. In the evaporation tank, the wastewater is heated under negative pressure to remove most of the water vapor and concentrated. The water vapor enters the gas collection chamber and is liquefied by the condenser. Floating impurities floating on the top of the wastewater are scraped into the impurity removal chamber by the scraper, and settling impurities settle to the bottom of the evaporation tank.

[0023] S3: The concentrated wastewater enters the impurity removal chamber through a pipette, and then enters the upper crystallization chamber through a gate on the other side of the impurity removal chamber;

[0024] S4: As the temperature decreases, NaCl crystals in the wastewater crystallize first;

[0025] S5: Wastewater with NaCl removed enters the lower crystallization chamber through a control valve and filter screen. As the temperature further decreases, Na2SO4 crystals precipitate out of the wastewater.

[0026] S6: Finally, the wastewater is discharged from the outlet pipe near the bottom of the crystallization chamber.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) This invention avoids the inhibitory effect of high-salt environment on microorganisms and adopts a purely physical separation method. First, aniline is heated and distilled to recover it. Then, the water is evaporated and concentrated under negative pressure. Finally, the difference in the solubility of NaCl and Na2SO4 in water with temperature is used to achieve fractional crystallization separation.

[0029] (2) The heat pipe of the present invention is simultaneously installed in the distillation chamber and the evaporation tank. The hot waste gas generated during the factory production process is passed into the heat pipe and directly exchanged with the sewage through the pipe wall, without the need for an additional steam boiler.

[0030] (3) The present invention extracts the raw materials from the waste liquid after use and reuses them. On the one hand, it reduces the pollution of the environment by the wastewater, and on the other hand, it recovers the raw materials to reduce the industrial production cost. For example, aniline can be recovered and reused in the indigo synthesis section. Attached Figure Description

[0031] Figure 1 A schematic diagram of the wastewater treatment device for indigo production provided by the present invention;

[0032] Figure 2 A front view of the wastewater treatment apparatus for indigo production provided by the present invention;

[0033] Figure 3 A top view of the wastewater treatment apparatus for indigo production provided by the present invention;

[0034] Figure 4 A side view of the wastewater treatment apparatus for indigo production provided by the present invention;

[0035] Figure 5 for Figure 4 Sectional view at point AA;

[0036] Figure 6 for Figure 5 Enlarged view of point A in the middle;

[0037] Figure 7 for Figure 3 A magnified view of a portion of the image.

[0038] The corresponding names of the reference numerals in the attached drawings are as follows: 10, Auxiliary part; 11, Submersible pump; 111, Liquid inlet pipe; 12, Condenser; 13, Gas collecting pipe; 131, Gas collecting head; 14, Reflux pump; 141, Reflux pipe; 15, Drain valve; 20, Distillation part; 21, Distillation chamber; 211, Exhaust port; 212, First motor; 213, Rotating shaft; 214, Impeller; 22, Gas collecting chamber; 221, Sealing door; 23. Sealing cap; 30. Evaporation section; 31. Evaporation tank; 32. Heat pipe; 33. Second motor; 321. Second chain; 34. First chain; 341. Scraper; 342. Driven gear; 40. Crystallization section; 41. Impurity removal chamber; 411. Pipette; 412. Gate; 413. Handwheel; 42. Crystallization chamber; 421. Partition; 422. Control valve; 43. Filter screen; 44. Discharge pipe. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments.

[0040] Example 1:

[0041] like Figure 1 As shown, the wastewater treatment device for indigo production provided by the present invention includes: an auxiliary unit 10, a distillation unit 20 connected to one side of the auxiliary unit 10, the distillation unit 20 being used to heat and distill aniline in the wastewater, an evaporation unit 30 connected to the other side of the distillation unit 20, the evaporation unit 30 heating to remove part of the water from the wastewater, thereby concentrating the wastewater, and a crystallization unit 40 installed on one side of the evaporation unit 30, where some salt is cooled and precipitated.

[0042] Specifically, such as Figure 1-5 As shown, the auxiliary unit 10 includes a submersible pump 11. The output end of the submersible pump 11 is connected to an inlet pipe 111. Wastewater is drawn in from the input end of the submersible pump 11, pressurized by the submersible pump 11, discharged from the inlet pipe 111, and transported to the distillation unit 20.

[0043] The condenser 12 of the auxiliary section 10 is a gas cooling and liquefaction device. Its inlet end is connected to the gas collecting pipe 13 and is used to cool and liquefy the received gas. One end of the gas collecting pipe 13 is connected to the condenser 12, and the other end extends into the gas collecting chamber 22 of the distillation section 20.

[0044] The distillation section 20 includes two parts: a distillation chamber 21 and a gas collecting chamber 22. The two parts are parallel and fixedly connected. Both the distillation chamber 21 and the gas collecting chamber 22 are sealed spaces and are connected by an exhaust port 211 fixedly installed on their common inner wall. A stirring assembly is installed in the distillation chamber 21 to stir the wastewater, so that the wastewater is heated evenly and the precipitation of aniline gas is accelerated. A gas collecting head 131 is fixedly installed at the end of the gas collecting pipe 13. The gas collecting head 131 has multiple air inlets and is located inside the gas collecting chamber 22 to collect the gas in the gas collecting chamber 22.

[0045] The stirring assembly includes a first motor 212, a rotating shaft 213, and impellers 214. The first motor 212 is fixedly installed on the top of the distillation chamber 21. The upper end of the rotating shaft 213 is fixedly connected to the output end of the first motor 212. The lower end of the rotating shaft 213 passes through the top wall of the distillation chamber 21 and extends into the internal cavity of the distillation chamber 21. The rotating shaft 213 and the top wall of the distillation chamber 21 are rotatably connected by bearings. A seal is provided at the connection. Multiple inclined blade impellers 214 are fixedly installed at equal intervals around the rotating shaft 213.

[0046] The evaporation section 30 includes an evaporation tank 31, which is a closed container with a negative pressure inside, thereby lowering the boiling point of the water in the wastewater and allowing the water to boil and evaporate at a lower temperature. A heat pipe 32 is fixedly installed on the inner wall of the evaporation tank 31. The heat pipe 32 is filled with hot waste gas generated during the factory production process. When the hot waste gas flows in the heat pipe 32, it exchanges heat with the wastewater in the evaporation tank 31 through the pipe wall and heats the wastewater to boiling, causing the water in the wastewater to evaporate and form water vapor. The water vapor generated by evaporation enters the gas collection chamber 22 through the pipe, and then enters the gas collection pipe 13 through the gas collection head 131, and is finally sent to the condenser 12 for liquefaction to obtain reusable condensate.

[0047] like Figure 5 and Figure 7 As shown, the crystallization section 40 includes a crystallization chamber 42 and a partition 421. The partition 421 is horizontally fixed on the side wall of the crystallization chamber 42, dividing the crystallization chamber 42 into two independent spaces, upper and lower. A filter assembly is installed on the partition 421. After the temperature of the wastewater in the upper crystallization chamber 42 naturally decreases, the NaCl in the wastewater first reaches saturation and crystallizes out. After being filtered by the filter assembly, the filtrate enters the lower crystallization chamber 42. As the temperature further decreases, the Na2SO4 in the wastewater reaches saturation and crystallizes out, realizing the graded recovery of the two salts.

[0048] Example 2:

[0049] like Figure 5As shown, a slot for gas flow is provided on the common side wall of the distillation chamber 21 and the gas collecting chamber 22. A sealing door 221 is rotatably installed at the slot. The sealing door 221 adopts a hinged rotatable installation structure, and one side of it is hinged to the common side wall. The sealing door 221 has two working states. First, in the distillation state, when the distillation chamber 21 is distilling aniline, the sealing door 221 is in the closed state, sealing the slot. At this time, the distillation chamber 21 and the gas collecting chamber 22 are connected only through the small hole of the exhaust port 211. First, aniline gas slowly enters the gas collecting chamber 22 from the space above the distillation chamber 21 through the exhaust port 211. Second, in the evaporation state, when the evaporation section 30 evaporates water vapor, the sealing door 221 is driven by an external motor to swing open towards the gas collecting chamber 22, increasing the opening area of ​​the slot. At this time, a large amount of water vapor generated in the evaporation tank 31 enters the gas collecting chamber 22 through the pipe and quickly enters the interior of the gas collecting chamber 22 through the slot with a larger opening, and is then absorbed by the gas collecting head 131 equipped with an air pump.

[0050] In addition, such as Figure 5 As shown, the top of the gas collecting chamber 22 and the evaporation tank 31 are fixedly connected and sealed with a sealing cover 23. A sealing gasket is provided between the sealing cover 23 and the gas collecting chamber 22 and the evaporation tank 31 to ensure the airtightness of the entire gas flow path and maintain the negative pressure state of the evaporation tank 31.

[0051] Example 3:

[0052] Please see Figure 3 , Figure 5 As shown, there are two sets of evaporation tanks 31, which are arranged side by side and independent of each other. The bottom of each set of evaporation tanks 31 is a conical structure. The sedimentation impurities in the sewage settle to the conical bottom of the evaporation tank 31 under the action of gravity, which is convenient to be discharged from the slag discharge port at the bottom.

[0053] Heat pipe 32 is installed on the inner wall of evaporation tank 31. The air inlet end of heat pipe 32 extends out of the side wall of evaporation tank 31 and is connected to the main hot exhaust gas pipe of the factory. The air outlet end extends out of the side wall of evaporation tank 31 and is connected to the exhaust gas treatment system. When hot exhaust gas flows through heat pipe 32, it transfers heat to the sewage in evaporation tank 31 through the pipe wall, causing the sewage temperature to rise to a boiling state. Since the evaporation tank 31 is under negative pressure, the water in the sewage can boil and evaporate at about 60-80℃.

[0054] like Figure 2-7As shown, a cleaning assembly is installed at the upper end of the evaporation tank 31. The cleaning assembly includes a second motor 33, which is fixedly installed on one side of the upper end of the evaporation tank 31. A drive sprocket is sleeved on the output end of the second motor 33. Two sets of driven gears 342 are rotatably installed at the upper end of the evaporation tank 31. The two sets of driven gears 342 are located on opposite sides of the evaporation tank 31. A first chain 34 is sleeved on both sets of driven gears 342. The first chain 34 rotates with the rotation of the driven gears 342. The output end of the second motor 33 is connected to the shaft of one of the driven gears 342 through the second chain 321.

[0055] A scraper 341 is fixedly installed on the first chain 34 along the width of the evaporation tank 31. The lower end of the scraper 341 is in contact with the liquid surface of the sewage in the evaporation tank 31. When the second motor 33 starts, the power is transmitted to the driven gear 342 through the second chain 321. The driven gear 342 drives the first chain 34 to rotate cyclically. When the scraper 341 rotates to the side of the first chain 34 that is close to the liquid surface, the scraper 341 moves in the horizontal direction to scrape off the floating impurities on the surface of the sewage in the evaporation tank 31, pushes the floating impurities to one side of the evaporation tank 31 and scrapes them into the impurity removal chamber 41.

[0056] Example 4:

[0057] like Figure 5 As shown, the impurity removal chamber 41 is located between the evaporation tank 31 and the crystallization chamber 42. A pipette 411 is installed on the side wall of the impurity removal chamber 41, which connects the impurity removal chamber 41 to the interior of the evaporation tank 31. The inlet end of the pipette 411 is located at a certain distance above the conical bottom of the evaporation tank 31. After the wastewater has been evaporated and concentrated, the sedimentary impurities in it have been deposited at the conical bottom of the evaporation tank 31. The pipette 411 draws the upper clear liquid from the top of the conical bottom. A valve is installed on the pipette 411 to control the flow of the concentrated wastewater from the evaporation tank 31 into the impurity removal chamber 41.

[0058] A gate 412 is provided on the other side of the impurity removal chamber 41. When the gate 412 is opened, it connects the impurity removal chamber 41 with the upper space of the crystallization chamber 42. A handwheel 413 is provided at the upper end of the gate 412. Rotating the handwheel 413 can control the opening and closing of the gate 412 and the degree of opening. This part is prior art, and its specific structure will not be described in detail here. When the gate 412 is opened, the sewage that has settled in the impurity removal chamber 41 enters the upper crystallization chamber 42 through the gate 412.

[0059] A reflux pipe 141 is also fixedly installed on the side wall of the evaporation tank 31. One end of the reflux pipe 141 extends into the evaporation tank 31 and the other end extends into the distillation chamber 21. A reflux pump 14 is installed on the reflux pipe 141. If the aniline content in the wastewater in the evaporation tank 31 still exceeds the standard after a period of evaporation, the wastewater can be pumped back to the distillation chamber 21 through the reflux pipe 141 for secondary distillation treatment to ensure that the aniline is fully removed.

[0060] In addition, such as Figure 2 As shown, drain valves 15 are installed on the side walls near the bottom of the distillation chamber 21, evaporation tank 31, impurity removal chamber 41, and crystallization chamber 42 to facilitate cleaning and drainage.

[0061] Example 5:

[0062] like Figure 5 As shown, the crystallization chamber 42 is rectangular, and its interior is divided into two independent crystallization chambers 42, upper and lower, by a partition 421. The partition 421 is horizontally fixed on the inner wall of the crystallization chamber 42, and the partition 421 is sealed to the side wall of the crystallization chamber 42.

[0063] The filter assembly includes a control valve 422 and a filter screen 43. The control valve 422 is mounted on a partition 421. The inlet end of the control valve 422 is connected to the interior of the upper crystallization chamber 42, and the outlet end is connected to the interior of the lower crystallization chamber 42, which is equivalent to the function of a valve. When the control valve 422 is opened, the liquid in the upper crystallization chamber 42 flows into the lower crystallization chamber 42 through the control valve 422.

[0064] The filter screen 43 is fixedly installed at the lower end of the partition plate 421, located below the outlet end of the control valve 422. The mesh size of the filter screen 43 can be determined according to the particle size of the NaCl crystals. When the liquid in the upper crystallization chamber 42 flows out through the control valve 422, the filter screen 43 traps the NaCl crystals suspended in the liquid in the upper crystallization chamber 42, while the filtrate rich in Na2SO4 enters the lower crystallization chamber 42 through the filter screen 43.

[0065] A liquid outlet pipe 44 is installed on the side wall of the lower crystallization chamber 42. The inlet end of the liquid outlet pipe 44 is located near the bottom of the crystallization chamber 42 and is used to discharge the tail liquid after final treatment. A valve can be installed on the liquid outlet pipe 44 to control the discharge of the tail liquid.

[0066] After being evaporated and concentrated, the wastewater enters the upper crystallization chamber 42. As the temperature gradually decreases from 60-80℃ during evaporation to room temperature, the solubility of NaCl in the wastewater decreases with decreasing temperature. When the NaCl concentration exceeds its solubility at that temperature, it first precipitates in crystal form. Since the density of NaCl crystals is greater than that of water, the precipitated NaCl crystals settle to the upper surface of the partition 421. The control valve 422 is opened, and the liquid enters the lower crystallization chamber 42 through the control valve 422 and the filter screen 43. The NaCl crystals are trapped by the filter screen 43, collected, and reused.

[0067] The filtrate entering the lower crystallization chamber 42 continues to cool down. As the solubility of Na2SO4 decreases significantly at low temperatures, Na2SO4 crystallizes out and settles to the bottom of the lower crystallization chamber 42. After collection, it can be used as a chemical raw material. Finally, the remaining small amount of tail liquid is discharged through the outlet pipe 44.

[0068] During operation, the submersible pump 11 is first started to draw wastewater from the equalization tank and transport it to the distillation chamber 21 through the inlet pipe 111. The first motor 212 is started to drive the rotating shaft 213 and the impeller 214 to rotate and stir. At the same time, steam or hot waste gas is introduced into the distillation chamber 21 through the heat pipe 32 to heat the wastewater to the boiling point of aniline. After the aniline is vaporized, it enters the gas collecting chamber 22 through the exhaust port 211, and is then absorbed by the gas collecting head 131 and sent to the condenser 12 through the gas collecting pipe 13 to be liquefied into liquid aniline for recovery. During this process, the sealing door 221 remains closed to maintain distillation. The temperature is stable; then the wastewater after aniline removal is pumped into the evaporation tank 31. The evaporation tank 31 is drawn to a negative pressure state by a vacuum pump. At the same time, hot waste gas is introduced through the heat pipe 32 to make the wastewater boil and evaporate. The generated water vapor enters the gas collection chamber 22 and is liquefied by the condenser 12 to obtain recycled water. The second motor 33 is started to drive the driven gear 342 and the first chain 34 to rotate in a cycle through the second chain 321. The scraper 341 drives the floating impurities on the surface of the wastewater to be scraped into the impurity removal chamber 41, while the settling impurities are precipitated to the conical bottom of the evaporation tank 31 and discharged.

[0069] Next, the upper concentrated liquid after the sedimentation of impurities in the evaporation tank 31 is sent to the impurity removal chamber 41 through the pipette 411. Then, the gate 412 is opened to allow it to enter the upper crystallization chamber 42. The concentrated liquid is naturally cooled in the upper crystallization chamber 42 so that NaCl first reaches saturation and crystallizes out onto the upper surface of the partition 421. The control valve 422 is opened to allow the upper liquid to flow into the lower crystallization chamber 42. The suspended NaCl crystals are intercepted by the filter screen 43. The filtrate continues to cool so that Na2SO4 crystallizes out to the bottom of the lower crystallization chamber 42. Finally, the remaining tail liquid after treatment is discharged from the outlet pipe 44 near the bottom of the crystallization chamber 42.

[0070] The above embodiments are merely one of the preferred embodiments of the present invention and should not be used to limit the scope of protection of the present invention. Any modifications or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but solve the same technical problem as the present invention, should be included within the scope of protection of the present invention.

Claims

1. A wastewater treatment device for indigo production, characterized in that, include: An auxiliary section (10) is connected to a distillation section (20) for heating and distilling aniline in wastewater. An evaporation section (30) is connected to one side of the distillation section (20). The evaporation section (30) is used to remove water from the wastewater. A crystallization section (40) is installed on one side of the evaporation section (30). The concentration of wastewater is increased after being treated by the evaporation section (30), and some salt is cooled and precipitated in the crystallization section (40). The auxiliary unit (10) includes a submersible pump (11), the output end of which is connected to an inlet pipe (111). Wastewater is drawn in from the input end of the submersible pump (11) and discharged from the inlet pipe (111). The auxiliary unit (10) also includes a condenser (12) for cooling and liquefying gas, and a gas collecting pipe (13) is installed on the condenser (12). The distillation section (20) includes a distillation chamber (21), and a gas collecting chamber (22) is fixedly connected to one side of the distillation chamber (21). Both the distillation chamber (21) and the gas collecting chamber (22) are closed spaces. The distillation chamber (21) and the gas collecting chamber (22) are connected by an exhaust hole (211) fixedly installed on their inner walls. A stirring assembly is installed in the distillation chamber (21). A gas collecting head (131) with multiple air inlets is fixedly installed at the end of the gas collecting pipe (13). The gas collecting head (131) is located in the gas collecting chamber (22). The evaporation section (30) includes an evaporation tank (31), which is under negative pressure. A heat pipe (32) is fixedly installed on the inner wall of the evaporation tank (31). Hot waste gas is introduced into the heat pipe (32) to heat the sewage in the evaporation tank (31) to boiling so that the water in the sewage evaporates. The evaporated water vapor enters the gas collection chamber (22) and enters the condenser (12) through the gas collection head (131) to liquefy. The crystallization section (40) includes a crystallization chamber (42). A partition (421) is horizontally fixed on the side wall of the crystallization chamber (42). The partition (421) divides the crystallization chamber (42) into two independent spaces, upper and lower. A filter assembly is installed on the partition (421). After the temperature of the wastewater in the upper crystallization chamber (42) decreases and NaCl crystallizes, it passes through the filter assembly and enters the lower crystallization chamber (42) to continue. As the temperature further decreases, Na2SO4 crystallizes out of the wastewater.

2. The wastewater treatment device for indigo production according to claim 1, characterized in that, The stirring assembly includes a first motor (212) fixedly installed on the top of the distillation chamber (21). The output end of the first motor (212) is fixedly installed on the upper end of a rotating shaft (213). The rotating shaft (213) passes through the top of the distillation chamber (21) and is rotatably connected to it. The lower end is located in the cavity inside the distillation chamber (21). Multiple blades (214) are fixedly installed at equal intervals around the rotating shaft (213).

3. The wastewater treatment device for indigo production according to claim 2, characterized in that, The distillation chamber (21) and the gas collection chamber (22) share a common side wall with a slot for gas flow. A sealing door (221) is rotatably installed at the slot. The sealing door (221) can swing left and right to open in different directions. When the distillation chamber (21) distills aniline, the sealing door (221) is closed. When the evaporation section (30) evaporates water vapor, the sealing door (221) is opened. Water vapor enters the gas collection chamber (22) through the slot at the sealing door (221).

4. The wastewater treatment device for indigo production according to claim 3, characterized in that, The top of the gas collection chamber (22) and the evaporation tank (31) are fixedly connected and sealed with a sealing cover (23).

5. The wastewater treatment device for indigo production according to claim 4, characterized in that, The evaporation tank (31) is provided in two sets. The bottom of the evaporation tank (31) is conical, and impurities in the sewage settle to the bottom of the evaporation tank (31).

6. The wastewater treatment device for indigo production according to claim 5, characterized in that, To address the floating impurities on the surface of the evaporation tank (31), a cleaning component is installed at the upper end of the evaporation tank (31). The cleaning component includes a second motor (33), and a second chain (321) is fitted onto the output end of the second motor (33). Two sets of driven gears (342) are rotatably installed at the upper end of the evaporation tank (31). A first chain (34) is fitted onto the two sets of driven gears (342). The first chain (34) rotates with the rotation of the driven gears (342). A scraper (341) is fixedly installed on the first chain (34). When the scraper (341) rotates to the lower spoke of the first chain (34), it scrapes off the floating impurities on the surface of the sewage in the evaporation tank (31). The scraped impurities enter the cleaning chamber (41).

7. The wastewater treatment device for indigo production according to claim 6, characterized in that, The impurity removal chamber (41) is located between the evaporation tank (31) and the crystallization chamber (42). A pipette (411) is installed on the side wall of the impurity removal chamber (41). The pipette (411) connects the impurity removal chamber (41) with the interior of the evaporation tank (31). The pipette (411) is located at the upper end of the conical bottom of the evaporation tank (31). A gate (412) is opened on the other side of the impurity removal chamber (41). The gate (412) connects the impurity removal chamber (41) with the crystallization chamber (42). A handwheel (413) is provided at the upper end of the gate (412). Turning the handwheel (413) controls the opening and closing of the gate (412). A reflux pipe (141) is also fixedly installed on the side wall of the evaporation tank (31). The water in the reflux pipe (141) is transported to the distillation chamber (21) by a reflux pump (14) installed on it.

8. The wastewater treatment device for indigo production according to claim 7, characterized in that, The filtration assembly includes a control valve (422) mounted on a partition (421), which controls the sewage in the upper crystallization chamber (42) to enter the lower crystallization chamber (42). A filter screen (43) is provided at the lower end of the control valve (422), and the filter screen (43) is fixedly mounted at the lower end of the partition (421). An outlet pipe (44) is installed on the side wall of the lower crystallization chamber (42).

9. A method for treating wastewater from indigo production, used in the wastewater treatment apparatus for indigo production as described in any one of claims 1-8, characterized in that, The method includes: S1: Wastewater is pumped into the inlet pipe (111) by the submersible pump (11) and transported to the distillation chamber (21). In the distillation chamber (21), the wastewater is heated by the heat pipe (32) fixedly installed inside and stirred by the blade (214) to release aniline gas and pass through the exhaust port (211) to the gas collection chamber (22). Then, the aniline gas is absorbed by the gas collecting head (131) and enters the gas collecting pipe (13) and is liquefied and recovered by the condenser (12). S2: The wastewater after removing aniline gas is pumped into the evaporation tank (31). The wastewater is heated under negative pressure in the evaporation tank (31) to remove most of the water vapor and concentrate it. The water vapor enters the gas collection chamber (22) and is liquefied by the condenser (12). The floating impurities floating on the top of the wastewater are scraped into the impurity removal chamber (41) by the scraper (341), and the settling impurities settle to the bottom of the evaporation tank (31). S3: The concentrated wastewater enters the impurity removal chamber (41) through the pipette (411), and then enters the upper crystallization chamber (42) through the gate (412) on the other side of the impurity removal chamber (41). S4: As the temperature decreases, NaCl crystals in the wastewater crystallize first; S5: The wastewater after removing NaCl enters the lower crystallization chamber (42) through the control valve (422) and the filter screen (43). As the temperature further decreases, Na2SO4 crystals out of the wastewater. S6: Finally, the wastewater is discharged from the outlet pipe (44) near the bottom of the crystallization chamber (42).

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