Treatment device for wet oxidation produced water of caprolactam wastewater

Abstract

The utility model relates to a treatment device for wet oxidation produced water of caprolactam wastewater. The treatment device comprises a produced water collection tank, a membrane filtration device, an electrolysis device, a macroporous adsorption resin column and a chelating adsorption resin column, a water outlet of the produced water collecting tank is connected with a water inlet of the membrane filtering device; a concentrated water outlet of the membrane filtration device is connected with a water inlet of the electrolysis device; a water outlet of the electrolysis device is connected with a lower water inlet of the macroporous resin column; the upper water outlet of the macroporous resin column is connected with the lower water inlet of the chelating resin column. The device disclosed by the utility model is simple in structure, large in treatment capacity, high in removal rate of COD (Chemical Oxygen Demand), environment-friendly, safe, reliable, low in cost and suitable for industrial production, and catalyst metal ions and ammonium sulfate are recycled, and no additional by-products and three wastes are generated.

Description

Technical Field

[0001] The utility model relates to a device for treating water produced by wet oxidation, in particular to a device for treating water produced by wet oxidation of caprolactam wastewater. Background Art

[0002] At present, the mainstream process for caprolactam production is the cyclohexanone liquid phase ammonia oximation method, which first generates cyclohexanone oxime from cyclohexanone, ammonia and hydrogen peroxide under the action of titanium silicon molecular sieve, and then the cyclohexanone oxime undergoes Beckmann rearrangement under the action of fuming sulfuric acid to generate caprolactam sulfate, which is neutralized with ammonia water to obtain a crude caprolactam aqueous solution, and finally the crude caprolactam aqueous solution is subjected to extraction, stripping, ion exchange, hydrogenation, evaporation, distillation and other steps to obtain refined caprolactam. In a series of complex production processes, cyclohexanone, cyclohexanone oxime and other difficult-to-degrade byproducts are produced. Therefore, caprolactam wastewater has the characteristics of high oxygen consumption and high toxicity. The discharge of untreated high-concentration caprolactam wastewater into nature will cause irreversible damage to the sustainable development of the ecosystem and even threaten human life and health. Therefore, exploring an economical and efficient method to treat caprolactam wastewater is the current primary goal.

[0003] Catalytic wet oxidation (CWAO) technology is a representative of wastewater thermal treatment technology. It uses oxidants, copper, iron, manganese, nickel or cobalt catalysts under high temperature and high pressure to catalytically oxidize organic matter in wastewater into CO2 and water, thereby achieving the purpose of removing pollutants. However, caprolactam production wastewater generally has the characteristics of high COD content, high salt content, and complex composition. Although catalytic wet oxidation can make the COD removal rate reach more than 98%, the removal rate of ammonia nitrogen is low, and all total nitrogen is converted into ammonia nitrogen. It is also impossible to remove inorganic salts (mainly ammonium sulfate) in the solution. The treated wastewater contains a large amount of ammonium sulfate and has poor biodegradability. In addition, there is still a small amount of COD in the produced water that is difficult to remove and cannot be directly discharged, so further treatment is required.

[0004] In summary, it is urgent to find a treatment device for wet oxidation water production of caprolactam wastewater with a simple structure, large processing capacity, high COD removal rate, recovery of catalyst metal ions and ammonium sulfate, no additional by-products and three wastes, green and environmentally friendly, safe and reliable, low cost, and suitable for industrial production. Utility Model Content

[0005] The technical problem to be solved by the utility model is to overcome the above-mentioned defects of the prior art and provide a treatment device for wet oxidation water production of caprolactam wastewater with a simple structure, large processing capacity, high COD removal rate, recovery of catalyst metal ions and ammonium sulfate, no additional by-products and three wastes, green and environmentally friendly, safe and reliable, low cost, and suitable for industrial production.

[0006] The technical solution adopted by the utility model to solve its technical problems is as follows: a treatment device for wet oxidation water production of caprolactam wastewater, comprising a water production collection tank, a membrane filtration device, an electrolysis device, a macroporous adsorption resin column and a chelating adsorption resin column; the water outlet of the water production collection tank is connected to the water inlet of the membrane filtration device; the concentrated water outlet of the membrane filtration device is connected to the water inlet of the electrolysis device; the water outlet of the electrolysis device is connected to the lower water inlet of the macroporous resin column; the upper water outlet of the macroporous resin column is connected to the lower water inlet of the chelating resin column.

[0007] Preferably, the produced water collection tank is provided with a water inlet and a pH value adjusting device.

[0008] Preferably, the membrane filtration device is provided with a fresh water outlet.

[0009] Preferably, the membrane is a nanofiltration membrane or a reverse osmosis membrane. Further preferably, the membrane is a nanofiltration membrane. The reverse osmosis membrane has a high removal rate for ions and a high removal rate for COD, while the nanofiltration membrane has a better selective separation ability, with a pore size between 0.1 and 2.0 nm. The nanofiltration membrane is between ultrafiltration and reverse osmosis, and can screen out substances with a molecular weight of about 100 to 2000 Daltons through pore size screening and charge action. It can retain most of the ammonium sulfate in concentrated water, but basically does not retain COD, thereby producing low-salinity fresh water, thereby achieving the ideal fresh water filtration and ammonium sulfate recovery effect, and the advantages of the nanofiltration membrane include low operating pressure, low energy consumption, high flux and relatively low investment and maintenance costs.

[0010] Preferably, the pore size of the membrane is 0.1-2.0 nm.

[0011] Preferably, the membrane filtration device is arranged in series in one or two stages.

[0012] Preferably, when the membrane filtration device adopts a two-stage series arrangement, the water outlet of the water production collection tank is connected to the water inlet of the first membrane filtration device; the concentrate water outlet of the first membrane filtration device is connected to the water inlet of the second membrane filtration device; the concentrate water outlet of the second membrane filtration device is connected to the water inlet of the electrolysis device; and a reflux channel is provided between the concentrate water outlet of the second membrane filtration device and the water inlet of the second membrane filtration device.

[0013] Preferably, the electrolysis device is provided with an electrolytic cell, the electrolytic cell is provided with positive and negative electrodes, and the positive and negative electrodes of the power supply can interchange directions.

[0014] Preferably, the electrode distance between the positive and negative electrodes is 5 to 30 mm.

[0015] Preferably, the anode and cathode electrodes are graphite electrodes, metal Pt electrodes or titanium-based DSA electrodes.

[0016] Preferably, the electrolysis device is provided with a fresh water outlet.

[0017] Preferably, the aspect ratio of the resin filler of the macroporous adsorption resin column is 2.5 to 5.0: 1. Further preferably, the height of the resin filler is 0.5 to 50 m.

[0018] Preferably, the macroporous resin type includes one or more of a macroporous polymeric adsorption resin, a macroporous weakly acidic cation exchange resin or a macroporous strongly basic type I anion exchange resin.

[0019] Preferably, the height-to-diameter ratio of the resin filler of the chelating resin column is 2.5 to 5.0: 1. Further preferably, the height of the resin filler is 0.5 to 50 m.

[0020] Preferably, the chelating resin type includes weakly acidic cation exchange resin, etc. Further preferably, the chelating resin includes Tulsimer® CH-90Na, SPC-90, etc.

[0021] Preferably, the chelating resin column is provided with an upper water outlet.

[0022] Preferably, a regulating valve is provided on the connecting pipeline of each component.

[0023] The working process of the utility model device is as follows: firstly, the wet oxidation water produced by the caprolactam wastewater stored in the produced water collection tank is adjusted in pH value by a pH value adjusting device, and then introduced from the water inlet of the membrane filtration device for membrane filtration, and then the concentrated water obtained by the membrane filtration is sent from the concentrated water outlet of the membrane filtration device to the water inlet of the electrolysis device, and the fresh water enters the biochemical system through the fresh water outlet of the membrane filtration device or is used for the cathode electrode regeneration in the electrolysis device; when the membrane filtration device adopts a two-stage series arrangement, the wet oxidation water produced by the caprolactam wastewater is introduced from the water inlet of the first membrane filtration device for membrane filtration, and the concentrated water obtained is sent from the water inlet of the second membrane filtration device for membrane filtration. A part of the obtained concentrated water flows back from the concentrated water outlet of the second membrane filtration device to the water inlet of the second membrane filtration device, and the remaining part is sent to the water inlet of the electrolysis device; in the electrolysis device, most of the catalyst metal ions in the concentrated water are reduced and deposited, and the COD substance is oxidized, and the obtained electrolytic wastewater is sent from the lower water inlet of the macroporous resin column to the macroporous adsorption resin column for resin adsorption to further remove COD, and then the adsorbed wastewater is sent from the lower water inlet of the chelating resin column to the chelating adsorption resin column for deep treatment to further remove the residual catalyst metal ions, and the ammonium sulfate in the obtained ammonium sulfate production water is highly concentrated and sent to the ammonium sulfate recovery system for evaporation and crystallization to obtain ammonium sulfate crystal by-product.

[0024] The beneficial effects of the treatment device of the utility model are as follows: the treatment device of the utility model has a simple structure and a large processing capacity, can remove COD at a high removal rate, recovers catalyst metal ions and ammonium sulfate, produces no additional by-products and three wastes, is green and environmentally friendly, safe and reliable, solves the applicability problem of the equipment through the combination of multiple process equipment, brings into play the best performance of each equipment, has low cost, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of a device for treating water produced by wet oxidation of caprolactam wastewater in Example 1 of the utility model;

[0026] Figure 2 This is a schematic diagram of a treatment device for wet oxidation water production of caprolactam wastewater in Example 2 of the utility model;

[0027] The reference numerals are as follows:

[0028] 1. Produced water collection tank; 1-1. Water outlet of produced water collection tank; 1-2. Water inlet of produced water collection tank; 1-3. pH value adjustment device;

[0029] 2. Membrane filtration device; 2-1. First membrane filtration device; 2-1-1. Water inlet of first membrane filtration device; 2-1-2. Concentrate water outlet of first membrane filtration device; 2-1-3. Fresh water outlet of first membrane filtration device; 2-2. Second membrane filtration device; 2-2-1. Water inlet of second membrane filtration device; 2-2-2. Concentrate water outlet of second membrane filtration device; 2-2-3. Fresh water outlet of second membrane filtration device;

[0030] 3. Electrolysis device; 3-1. Water inlet of electrolysis device; 3-2. Water outlet of electrolysis device; 3-3. Electrolysis cell; 3-4. Cathode and cathode electrodes; 3-5. Power supply; 3-6. Fresh water outlet of electrolysis device;

[0031] 4. Macroporous adsorption resin column; 4-1. Lower water inlet of the macroporous adsorption resin column; 4-2. Upper water outlet of the macroporous adsorption resin column;

[0032] 5. Chelating adsorption resin column; 5-1. Lower water inlet of the chelating adsorption resin column; 5-2. Upper water outlet of the chelating adsorption resin column;

[0033] 6. Regulating valve. DETAILED DESCRIPTION

[0034] The utility model is further described below in conjunction with embodiments and drawings.

[0035] Example 1

[0036] like Figure 1As shown, a device for treating water produced by wet oxidation of caprolactam wastewater comprises a water production collection tank 1, a membrane filter device 2, an electrolysis device 3, a macroporous adsorption resin column 4 and a chelating adsorption resin column 5; the membrane filter device 2 is arranged in two stages in series, the water outlet 1-1 of the water production collection tank 1 is connected to the water inlet 2-1-1 of the first membrane filter device 2-1; the concentrated water outlet 2-1-2 of the first membrane filter device 2-1 is connected to the water inlet 2-2 of the second membrane filter device 2-2 -1 is connected; the concentrated water outlet 2-2-2 of the second membrane filtration device 2-2 is connected to the water inlet 3-1 of the electrolysis device 3; a reflux channel is provided between the concentrated water outlet 2-2-2 of the second membrane filtration device 2-2 and the water inlet 2-2-1 of the second membrane filtration device 2-2; the water outlet 3-2 of the electrolysis device 3 is connected to the lower water inlet 4-1 of the macroporous resin column 4; the upper water outlet 4-2 of the macroporous resin column 4 is connected to the lower water inlet 5-1 of the chelating resin column 5;

[0037] The produced water collection tank 1 is provided with a water inlet 1-2 and a pH value adjusting device 1-3; the first membrane filtration device 2-1 and the second membrane filtration device 2-2 are both provided with fresh water outlets 2-1-3 and 2-2-3; the membrane is a nanofiltration membrane with a pore size of 0.7nm; the electrolysis device 3 is provided with an electrolytic cell 3-3, and the electrolytic cell 3-3 is provided with a positive and negative electrodes 3-4, and the positive and negative electrodes of the power supply 3-5 can interchange directions; the electrode spacing of the positive and negative electrodes 3-4 is 10mm, wherein the area of ​​the anode electrode is 5.5m 2 ; The anode and cathode electrodes 3-4 are both metal Pt electrodes; the electrolysis device 3 is provided with a fresh water outlet 3-6; the resin filler aspect ratio of the macroporous adsorption resin column 4 is 3:1, the resin filler height is 3m, and the macroporous resin type is a macroporous polymeric adsorption resin; the resin filler aspect ratio of the chelating resin column 5 is 3:1, the resin filler height is 3m, and the chelating resin type is a weakly acidic cation exchange resin Tulsimer® CH-90Na; the chelating resin column 5 is provided with an upper water outlet 5-2; and a regulating valve 6 is provided on the connecting pipelines of each component.

[0038] The working process of the utility model device is as follows: firstly, the pH value of the wet oxidation produced water of the caprolactam wastewater stored in the produced water collection tank 1 is adjusted by the pH value adjusting device 1-3, and then introduced from the water inlet 2-1-1 of the first membrane filtration device 2-1 for membrane filtration, and the obtained concentrated water is sent from the water inlet 2-2-1 of the second membrane filtration device 2-2 for membrane filtration, and a part of the obtained concentrated water is refluxed from the concentrated water outlet 2-2-2 of the second membrane filtration device 2-2 to the water inlet 2-2-1 of the second membrane filtration device 2-2, and the remaining part is sent to the water inlet 3-1 of the electrolysis device 3, and the fresh water passes through the fresh water outlet 2-2-2 of the first membrane filtration device 2-1 and the second membrane filtration device 2-2. The water outlets 2-1-3 and 2-2-3 enter the biochemical system or are used for regeneration of the cathode electrode 3-4 in the electrolysis device 3. In the electrolysis device 3, most of the catalyst metal ions in the concentrated water are reduced and deposited, while the COD substance is oxidized. The obtained electrolytic wastewater is sent to the macroporous adsorption resin column 4 from the lower water inlet 4-1 of the macroporous resin column 4 for resin adsorption to further remove COD. The adsorbed wastewater is then sent to the chelating adsorption resin column 5 from the lower water inlet 5-1 of the chelating resin column 5 for deep treatment to further remove the residual catalyst metal ions. The ammonium sulfate in the obtained ammonium sulfate production water is highly concentrated and sent to the ammonium sulfate recovery system for evaporation and crystallization to obtain ammonium sulfate crystal by-product.

[0039] Example 2

[0040] like Figure 2 As shown, the difference between the wet oxidation water treatment device of caprolactam wastewater in the embodiment of the utility model and the embodiment 1 is that: the membrane filter device 2 is arranged in one section, that is, the first membrane filter device 2-1, the water outlet 1-1 of the water collection tank 1 is connected to the water inlet 2-1-1 of the first membrane filter device 2-1; the concentrated water outlet 2-1-2 of the first membrane filter device 2-1 is connected to the water inlet 3-1 of the electrolysis device 3. The rest is the same as the embodiment 1.

[0041] The working process of the device of the embodiment of the utility model is different from that of the embodiment 1 only in that: the wet oxidation produced water of the caprolactam wastewater stored in the produced water collection tank 1 is first adjusted with the pH value adjusting device 1-3, and then introduced from the water inlet 2-1-1 of the first membrane filtration device 2-1 for membrane filtration, and the obtained concentrated water is sent from the concentrated water outlet 2-1-2 of the first membrane filtration device 2-1 to the water inlet 3-1 of the electrolysis device 3, and the fresh water enters the biochemical system through the fresh water outlet 2-1-3 of the first membrane filtration device 2-1 or is used for the regeneration of the cathode electrode 3-4 in the electrolysis device 3. The rest is the same as the embodiment 1.

Claims

1. A device for treating water produced by wet oxidation of caprolactam wastewater, characterized in that: It includes a produced water collection tank, a membrane filtration device, an electrolysis device, a macroporous adsorption resin column and a chelating adsorption resin column; the water outlet of the produced water collection tank is connected to the water inlet of the membrane filtration device; the concentrated water outlet of the membrane filtration device is connected to the water inlet of the electrolysis device; the water outlet of the electrolysis device is connected to the lower water inlet of the macroporous resin column; the upper water outlet of the macroporous resin column is connected to the lower water inlet of the chelating resin column.

2. The device for treating water produced by wet oxidation of caprolactam wastewater according to claim 1, characterized in that: The produced water collection tank is provided with a water inlet and a pH value adjusting device; the membrane filtration device is provided with a fresh water outlet; the membrane is a nanofiltration membrane or a reverse osmosis membrane; the pore size of the membrane is 0.1-2.0 nm.

3. The device for treating water produced by wet oxidation of caprolactam wastewater according to claim 1 or 2, characterized in that: The membrane filtration device is arranged in series in one or two stages; when the membrane filtration device is arranged in series in two stages, the outlet of the produced water collection tank is connected to the water inlet of the first membrane filtration device; the concentrate water outlet of the first membrane filtration device is connected to the water inlet of the second membrane filtration device; the concentrate water outlet of the second membrane filtration device is connected to the water inlet of the electrolysis device; a reflux channel is provided between the concentrate water outlet of the second membrane filtration device and the water inlet of the second membrane filtration device.

4. The device for treating water produced by wet oxidation of caprolactam wastewater according to claim 1 or 2, characterized in that: The electrolysis device is provided with an electrolytic cell, in which positive and negative electrodes are provided, and the positive and negative electrodes of the power supply can interchange directions; the electrode spacing between the positive and negative electrodes is 5 to 30 mm; the positive and negative electrodes are graphite electrodes, metal Pt electrodes or titanium-based DSA electrodes; and the electrolysis device is provided with a fresh water outlet.

5. The device for treating water produced by wet oxidation of caprolactam wastewater according to claim 3, characterized in that: The electrolysis device is provided with an electrolytic cell, in which positive and negative electrodes are provided, and the positive and negative electrodes of the power supply can interchange directions; the electrode spacing between the positive and negative electrodes is 5 to 30 mm; the positive and negative electrodes are graphite electrodes, metal Pt electrodes or titanium-based DSA electrodes; and the electrolysis device is provided with a fresh water outlet.

6. The device for treating water produced by wet oxidation of caprolactam wastewater according to claim 1 or 2, characterized in that: The height-to-diameter ratio of the resin filler of the macroporous adsorption resin column is 2.5-5.0:1; the macroporous resin type includes one or more of macroporous polymeric adsorption resin, macroporous weakly acidic cation exchange resin or macroporous strongly basic type I anion exchange resin; the height-to-diameter ratio of the resin filler of the chelating resin column is 2.5-5.0:1; the chelating resin type includes weakly acidic cation exchange resin; the chelating resin column is provided with an upper water outlet; and a regulating valve is provided on the connecting pipelines of each component.

7. The device for treating water produced by wet oxidation of caprolactam wastewater according to claim 3, characterized in that: The height-to-diameter ratio of the resin filler of the macroporous adsorption resin column is 2.5-5.0:1; the macroporous resin type includes one or more of macroporous polymeric adsorption resin, macroporous weakly acidic cation exchange resin or macroporous strongly basic type I anion exchange resin; the height-to-diameter ratio of the resin filler of the chelating resin column is 2.5-5.0:1; the chelating resin type includes weakly acidic cation exchange resin; the chelating resin column is provided with an upper water outlet; and a regulating valve is provided on the connecting pipelines of each component.

8. The device for treating water produced by wet oxidation of caprolactam wastewater according to claim 4, characterized in that: The height-to-diameter ratio of the resin filler of the macroporous adsorption resin column is 2.5-5.0:1; the macroporous resin type includes one or more of macroporous polymeric adsorption resin, macroporous weakly acidic cation exchange resin or macroporous strongly basic type I anion exchange resin; the height-to-diameter ratio of the resin filler of the chelating resin column is 2.5-5.0:1; the chelating resin type includes weakly acidic cation exchange resin; the chelating resin column is provided with an upper water outlet; and a regulating valve is provided on the connecting pipelines of each component.

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