Wastewater treatment system and method for catalytic wet oxidation

Abstract

The invention discloses a wastewater treatment system and method for catalytic wet oxidation, and the treatment system comprises a vortex bubble generator; the oxidation reactor is positioned at the downstream of the vortex bubble generator; the heater is positioned at the upstream of the vortex bubble generator; and a preheater located upstream of the heater. According to the treatment system disclosed by the invention, the vortex effect of the wastewater is enhanced under the dual effects of the flow guide slit and the flow guide spiral of the vortex bubble generator, and the micro-nano bubble generation efficiency is improved. In the catalytic wet oxidation reaction process, oxygen enters the oxidation reactor in the form of micro-nano bubbles, and compared with millimeter-scale bubbles in a traditional gas distribution mode, the retention time of the oxygen is prolonged, the specific surface area of the bubbles is large, the gas-liquid mass transfer rate is increased, the generation rate of free radicals is increased, and the catalytic wet oxidation reaction efficiency is improved. Meanwhile, oxygen enters the oxidation reactor in the form of micro-nano bubbles, so that the consumption of the oxygen is reduced while the reaction efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of high-salt organic wastewater treatment, specifically relating to a wastewater treatment system and method for catalytic wet oxidation. Background Technology

[0002] High-salinity organic wastewater is commonly found in industries such as chemical, pharmaceutical, dye, and food processing. The total salt content in high-salinity organic wastewater typically ranges from 1% to 30%, or even higher. The chemical oxygen demand (COD) is usually in the thousands to tens of thousands of mg / L, with some industries reaching over 100,000 mg / L. High-salinity organic wastewater contains a wide variety of organic compounds, including alkanes, aromatic compounds, heterocyclic compounds, oils, and surfactants, some of which are recalcitrant or biotoxic. Its high salt content, high COD, and complex composition make traditional treatment methods, such as biological treatment, insufficient.

[0003] Catalytic wet oxidation is one of the best methods for treating wastewater with high salinity, high COD, and complex composition. It utilizes oxygen or air as an oxidant under high temperature (150–320℃) and high pressure (0.5–10 MPa) conditions to initiate a free radical chain reaction, gradually decomposing organic matter into CO2, H2O, and small, harmless molecules. Catalytic wet oxidation can effectively oxidize various high-concentration organic wastewaters (including highly toxic wastewaters that are difficult to degrade using conventional methods) with almost no selectivity, and it does not produce secondary pollution.

[0004] Catalysts used in catalytic wet oxidation can be classified into homogeneous and heterogeneous catalysts based on their state. Heterogeneous catalysts are mainly prepared by supporting noble metals such as Ru, Rh, Pt, Pd, Ir, and Au on a support. They possess excellent catalytic performance and do not require additional catalyst recovery. However, they suffer from drawbacks such as high mass transfer resistance and high cost. Furthermore, during long-term operation, catalyst deactivation may occur due to the dissolution of active components, support sintering, or carbon deposition, necessitating periodic catalyst replacement. Homogeneous catalysts are mainly composed of transition metal salts such as Cu, Fe, and Mn. They are uniformly dispersed in the liquid phase in molecular or ionic form, with uniform active centers that can directly participate in the oxidation reaction. Homogeneous catalytic wet oxidation equipment and processes are simple, but they suffer from drawbacks such as complex catalyst recovery processes, susceptibility to secondary pollution, and low treatment efficiency.

[0005] Micro- and nanobubbles refer to bubbles with a diameter of less than 50 μm. They possess physical and chemical properties not found in conventional bubbles, such as large specific surface area, slow rising speed, self-pressurization and dissolution, surface charging, and generation of a large number of free radicals. Based on these properties, micro- and nanobubbles themselves have a certain ability to decompose pollutants. Micro- and nanobubbles can also be used in conjunction with flotation or ozone to enhance the treatment effect. However, in catalytic wet oxidation, due to the high temperature and high pressure reaction conditions, the application of micro- and nanobubbles is rarely reported. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention utilizes a specific vortex bubble generator structure to introduce oxygen into the catalytic wet oxidation reactor in the form of micro-nano bubbles, thereby significantly improving the treatment efficiency of high-salt organic wastewater.

[0007] This invention provides a wet oxidation wastewater treatment system, which includes a vortex bubble generator;

[0008] An oxidation reactor located downstream of the vortex bubble generator;

[0009] A heater located upstream of the vortex bubble generator;

[0010] and a preheater located upstream of the heater.

[0011] According to an embodiment of the present invention, the vortex bubble generator includes an outer vortex cylinder, a narrowing pipe, a throat pipe, and an expanding pipe connected in sequence. An inner vortex cylinder is provided inside the outer vortex cylinder, and the central axes of the outer vortex cylinder, the inner vortex cylinder, the narrowing pipe, the throat pipe, and the expanding pipe are on a straight line.

[0012] In some embodiments, a liquid inlet is provided on the side wall of the outer rotating cylinder. Preferably, a first liquid inlet and a second liquid inlet are provided opposite to each other on the side wall of the outer rotating cylinder.

[0013] In some embodiments, the end of the inner rotating cylinder coincides with or is closely fitted to the end of the outer rotating cylinder. Preferably, the outer rotating cylinder and the inner rotating cylinder are fixed by concentric discs.

[0014] In some implementations, the end of the inner vortex cylinder is provided with a gas inlet, the inner vortex cylinder is provided with a vortex zone, and the outlet end of the inner vortex cylinder is connected to the reduced diameter pipe.

[0015] In some embodiments, the throat tube is a straight tube, and the ratio of the diameter of the throat tube to the diameter of the inlet end of the reduced-bore tube is 0.16-0.24, for example, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23 or 0.24.

[0016] In some implementations, the inlet end of the expansion tube is connected to the other end of the throat tube, and the outlet end of the expansion tube is provided with a discharge port for gas and liquid to exit simultaneously.

[0017] In some embodiments, the ratio of the diameter of the throat tube to the diameter of the outlet end of the expansion tube is 0.16-0.24, for example, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23 or 0.24.

[0018] In some implementations, an air distribution pipe is provided inside the inner swirl cylinder, and the air distribution pipe is arranged coaxially with the inner swirl cylinder.

[0019] In some embodiments, the air distribution pipe has micron-sized sieve pores. Preferably, the pore size of the micron-sized sieve pores is 0.5μm-2μm, for example, 0.5μm, 0.6μm, 0.8μm, 1.0μm, 1.2μm, 1.5μm, or 2μm.

[0020] In some embodiments, the ratio of the diameter of the air distribution pipe to the diameter of the straight section of the inner vortex cylinder is 0.15-0.35, for example, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.25, 0.28, 0.30 or 0.35.

[0021] In some embodiments, a guide spiral is provided axially inside the inner swirl cylinder. Preferably, the guide spiral is connected to the inner wall of the inner swirl cylinder. Further, the ratio of the width of the guide spiral to the inner diameter of the inner swirl cylinder is 0.1-0.2, for example, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, or 0.2.

[0022] In some embodiments, the inner swirling barrel is assembled from four arc-shaped plates, with gaps between adjacent arc-shaped plates forming guide slits. Preferably, the width of the guide slits is 3mm-10mm, for example, 3mm, 5mm, 8mm, or 10mm.

[0023] The liquid enters the outer vortex cylinder and then enters the inner vortex cylinder through the guide slit formed by the gap between two adjacent arc-shaped plates. The gas enters the inner vortex cylinder through the gas inlet and is then diverted by the gas distribution pipe. The gas-liquid mixture flows through the guide spiral and forms a strong vortex gas flow in the inner vortex cylinder.

[0024] In some embodiments, the guide spiral and the air distribution pipe are at a certain distance. Preferably, the ratio of the maximum distance between the guide spiral and the air distribution pipe to the diameter of the inner vortex cylinder is 0.125-0.325, for example, 0.125, 0.2, 0.25, 0.3 or 0.325.

[0025] According to an embodiment of the present invention, the oxidation reactor further includes components required for the catalytic wet oxidation reaction. These components include, but are not limited to, one or more selected from an inlet unit, an outlet unit, a feed unit, a discharge unit, and an instrumentation unit. Those skilled in the art will understand that when the reactor is equipped with the aforementioned components, these components should not affect the airtightness of the reactor. For this purpose, the components can be connected to the reactor by welding, flanges, and / or piping. It should be understood that the structure and function of these components are known in the art. For example, the inlet and outlet units can be used to introduce oxygen and / or air to enable the catalytic wet oxidation reaction. The feed unit can be used to introduce wastewater requiring treatment, and the discharge unit can be used to discharge reaction products or undesirable residues. The instrumentation unit can be used to display or monitor the process parameters of the reactor.

[0026] In some implementations, the feeding unit is connected to the outlet end of the expansion tube of the vortex bubble generator.

[0027] In some implementations, the instrumentation unit includes a temperature sensor, a pressure sensor, an online TOC analyzer, an online pH meter, an online copper ion detector, and a level sensor. Preferably, the temperature sensor, pressure sensor, and level sensor are interlocked.

[0028] According to an embodiment of the invention, the processing system further includes a high-pressure pump located upstream of the preheater.

[0029] According to an embodiment of the present invention, the treatment system further includes a wastewater storage unit located upstream of the high-pressure pump. For example, the wastewater storage unit is a wastewater tank.

[0030] According to an embodiment of the present invention, the processing system further includes a pressure-reducing tank located downstream of the preheater, the pressure-reducing tank being connected to the preheater.

[0031] According to an embodiment of the present invention, the processing system further includes a catalyst recovery unit located downstream of the pressure reducing tank, the catalyst recovery unit being connected to the liquid phase outlet of the pressure reducing tank. For example, the catalyst recovery unit is selected from a membrane filter assembly in a membrane filtration catalyst recovery device for a wet oxidation process disclosed in CN219441259U.

[0032] In some embodiments, the processing system further includes a brine buffer unit located downstream of the catalyst recovery unit, the brine buffer unit being connected to the liquid phase outlet of the catalyst recovery unit. For example, the brine buffer unit is a brine buffer tank.

[0033] In some embodiments, the processing system further includes a catalyst regeneration unit located downstream of the catalyst recovery unit, the catalyst regeneration unit being connected to the solid phase outlet of the catalyst recovery unit.

[0034] The present invention also provides a wastewater treatment method, comprising, in the above-mentioned treatment system, causing wastewater to react with oxygen in a vortex bubble generator to form wastewater containing oxygen micro-nano bubbles, and then entering an oxidation reactor for catalytic wet oxidation reaction to achieve wastewater purification.

[0035] According to an embodiment of the present invention, the median particle size D of the oxygen-containing micro / nano bubbles 50 It is 20–40 μm, for example, 31 μm.

[0036] According to an embodiment of the present invention, the method includes pressurizing the wastewater in the wastewater storage unit by a high-pressure pump and then transporting it to a preheater for preheating, then heating it in a heater, then entering a vortex bubble generator to react with oxygen to form wastewater containing oxygen micro-nano bubbles, and then carrying out a catalytic wet oxidation reaction in an oxidation reactor to achieve wastewater purification.

[0037] According to an embodiment of the present invention, the ratio of the oxygen flow rate entering the gas distribution pipe through the gas inlet to the oxygen flow rate entering the oxidation reactor through the gas inlet unit is 1:2 to 7, for example, 1:2, 1:2.5, 1:3, 1:4, 1:5, 1:6 or 1:7.

[0038] According to an embodiment of the present invention, the operating temperature of the reactor is between 150-280°C, for example 150°C, 180°C, 200°C, 220°C, 240°C, 270°C or 280°C, and the pressure of the reactor is between 4-7 MPa, for example 5 MPa.

[0039] According to an embodiment of the present invention, during the catalytic wet oxidation reaction, the pH value of the wastewater is between 0.8 and 1.4, for example 0.8, 0.9, 1.0, 1.1, 1.2, 1.3 or 1.4.

[0040] According to an embodiment of the present invention, the catalyst used in the catalytic wet oxidation reaction can be any catalyst known in the art for use in catalytic wet oxidation methods, preferably a copper-containing catalyst. For example, the copper ion content is between 1000-3000 ppm.

[0041] According to an embodiment of the present invention, the wastewater treatment method includes the following steps:

[0042] High-salt organic wastewater is pumped into a preheater to exchange heat with the brine discharged from the oxidation reactor. It then enters a heater for further heating. The high-salt organic wastewater enters a vortex bubble generator through a liquid inlet located on the outer vortex cylinder. Oxygen is divided into two streams: one stream enters the vortex bubble generator through a gas inlet located at the end of the inner vortex cylinder, forming micro-nano bubbles. The wastewater containing these oxygen micro-nano bubbles enters the oxidation reactor. The other stream enters the oxidation reactor through an air intake unit (e.g., a gas distribution plate) at the bottom of the reactor, where it undergoes a catalytic wet oxidation reaction to decompose organic matter. After the reaction is complete, the wastewater enters the preheater to exchange heat with the high-salt organic wastewater.

[0043] In some embodiments, the treatment method further includes depressurizing the wastewater generated by the oxidation reactor by introducing it into a pressure reducing tank to obtain oxidized brine.

[0044] In some embodiments, the treatment method further includes adjusting the pH of the oxidized brine to alkaline, causing the catalyst to form a flocculent precipitate, and recovering the catalyst using a membrane filter to obtain refined brine.

[0045] The beneficial effects of this invention:

[0046] (1) In the treatment system of the present invention, the wastewater is enhanced by the dual action of the guide slit and the guide spiral of the vortex bubble generator, which improves the efficiency of micro-nano bubble generation.

[0047] (2) In this invention, oxygen enters the bubble generator through the gas distribution pipe. The gas distribution pipe has micron-sized sieve holes to cut the gas, thereby further improving the generation rate of micro and nano bubbles.

[0048] (3) In this invention, the wastewater undergoes a first cavitation in the vortex zone formed by the inner vortex tube to generate micro-nano bubbles, and a second cavitation occurs in the expanded diameter pipe section to further generate micro-nano bubbles, thereby increasing the generation rate of micro-nano bubbles.

[0049] (4) The vortex bubble generator of the present invention does not require external electric field, sound field and other energy, and has low operating cost.

[0050] (5) In the catalytic wet oxidation process of the present invention, oxygen enters the oxidation reactor in the form of micro-nano bubbles. Compared with the millimeter-sized bubbles of the traditional gas distribution method, the residence time of oxygen is extended, the specific surface area of ​​the bubbles is larger, the gas-liquid mass transfer rate is increased, the free radical generation rate is increased, and the efficiency of catalytic wet oxidation reaction is improved.

[0051] (6) In this invention, oxygen enters the oxidation reactor in the form of micro-nano bubbles, which improves the reaction efficiency while reducing the consumption of oxygen.

[0052] (7) The catalytic wet oxidation reaction conditions of the present invention require a high reaction pressure, and a higher pressure is beneficial to obtaining micro-nano bubbles with smaller particle size. Attached Figure Description

[0053] Figure 1 This is a wastewater treatment process flow chart;

[0054] Figure 2 This is a front view of the vortex bubble generator;

[0055] Figure 3 This is a cross-sectional view of a vortex bubble generator;

[0056] Figure 4 This is a longitudinal section view of the vortex bubble generator;

[0057] 1-Wastewater tank; 2-High-pressure pump; 3-Preheater; 4-Heater; 5-Vortex bubble generator; 6-Oxidation reactor; 7-Gas distribution plate; 8-Pressure reducing tank; 9-Filter membrane module; 10-Catalyst dissolution tank; 11-Refined brine buffer tank;

[0058] 501-First liquid inlet; 502-Second liquid inlet; 503-Gas inlet; 504-Guide spiral; 505-Gas distribution pipe; 506-Reducing diameter pipe; 507-Throat pipe; 508-Expanding diameter pipe; 509-Guide slit; 510-Outer swirl cylinder; 511-Inner swirl cylinder. Detailed Implementation

[0059] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0060] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0061] Example 1

[0062] A wet oxidation wastewater treatment system includes a vortex bubble generator 5;

[0063] Oxidation reactor 6 is located downstream of vortex bubble generator 5;

[0064] Heater 4 is located upstream of vortex bubble generator 5;

[0065] and a preheater located upstream of heater 4.

[0066] The vortex bubble generator 5 includes an outer vortex cylinder 510, a narrowing pipe 506, a throat pipe 507, and an expanding pipe 508 connected in sequence. An inner vortex cylinder 511 is provided inside the outer vortex cylinder 510. The central axes of the outer vortex cylinder 510, the inner vortex cylinder 511, the narrowing pipe 506, the throat pipe 507, and the expanding pipe 508 are on a straight line.

[0067] The outer rotating cylinder 510 has a first liquid inlet 501 and a second liquid inlet 502 on its side wall.

[0068] The outer rotating cylinder 510 and the inner rotating cylinder 511 are fixed by concentric discs, so that the end of the inner rotating cylinder 511 coincides with or is closely attached to the end of the outer rotating cylinder 510.

[0069] The inner swirl cylinder 511 has a gas inlet 503 at its end, a vortex zone inside the inner swirl cylinder 511, and its outlet end is connected to the reduced diameter pipe 506.

[0070] The throat tube 507 is a straight tube, and the ratio of the diameter of the throat tube 507 to the diameter of the inlet end of the reduced diameter tube 506 is 0.16-0.24, for example, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23 or 0.24.

[0071] The inlet end of the expansion pipe 508 is connected to the other end of the throat pipe 507, and the outlet end of the expansion pipe 508 is provided with a discharge port for gas and liquid to exit simultaneously.

[0072] The ratio of the diameter of the throat tube 507 to the diameter of the outlet end of the expansion tube 508 is 0.16-0.24, for example, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23 or 0.24.

[0073] An air distribution pipe 505 is provided inside the inner swirl cylinder 511, and the air distribution pipe 505 is arranged coaxially with the inner swirl cylinder 511.

[0074] The air distribution pipe 505 has micron-sized sieve holes. Preferably, the pore size of the micron-sized sieve holes is 0.5μm-2μm, for example, 0.5μm, 0.6μm, 0.8μm, 1.0μm, 1.2μm, 1.5μm, or 2μm.

[0075] The ratio of the diameter of the air distribution pipe 505 to the diameter of the straight section of the inner swirl cylinder 511 is 0.15-0.35, for example, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.25, 0.28, 0.30 or 0.35.

[0076] A flow-guiding spiral 504 is provided axially inside the inner swirl cylinder 511. Preferably, the flow-guiding spiral 504 is connected to the inner wall of the inner swirl cylinder 511. Further, the ratio of the width of the flow-guiding spiral 504 to the inner diameter of the inner swirl cylinder 511 is 0.1-0.2.

[0077] The inner swirl barrel 511 is assembled from four arc-shaped plates, and there is a gap between two adjacent arc-shaped plates to form a guide slit 509. Preferably, the width of the guide slit 509 is 3mm-10mm, for example, 3mm, 5mm, 8mm, or 10mm.

[0078] The liquid enters the outer swirl cylinder 510, passes through the guide slit 509 and enters the inner swirl cylinder 511. The gas enters the gas distribution pipe 505 through the gas inlet 503 and then enters the inner swirl cylinder 511. The gas-liquid mixture flows through the guide spiral 504 and forms a strong vortex gas flow in the inner swirl cylinder 511.

[0079] There is a certain distance between the guide spiral 504 and the air distribution pipe 505. Preferably, the ratio of the maximum distance between the guide spiral 504 and the air distribution pipe 505 to the diameter of the inner swirl cylinder 511 is 0.125-0.325, for example, 0.125, 0.2, 0.25, 0.3 or 0.325.

[0080] The oxidation reactor 6 also includes components required for the catalytic wet oxidation reaction. These components include, but are not limited to, one or more selected from the following: an inlet unit, an outlet unit, a feed unit, a discharge unit, and an instrumentation unit. Those skilled in the art will understand that when the reactor is equipped with the aforementioned components, the components should not affect the reactor's airtightness. For this purpose, the components can be connected to the reactor by welding, flanges, and / or piping. It should be understood that the structure and function of the components are known in the art. For example, the inlet and outlet units can be used to introduce oxygen and / or air to enable the catalytic wet oxidation reaction. The feed unit can be used to introduce wastewater requiring treatment, and the discharge unit can be used to discharge reaction products or undesirable residues. The instrumentation unit can be used to display or monitor the reactor's process parameters.

[0081] The feeding unit is connected to the outlet end of the expansion tube 508 of the vortex bubble generator 5.

[0082] The instrument unit includes a temperature sensor, a pressure sensor, an online TOC analyzer, an online pH meter, an online copper ion detector, and a liquid level sensor. Preferably, the temperature sensor, pressure sensor, and liquid level sensor are interlocked.

[0083] The processing system also includes a high-pressure pump 2 located upstream of the preheater.

[0084] The treatment system also includes a wastewater storage unit located upstream of the high-pressure pump 2. For example, the wastewater storage unit is a wastewater tank 1.

[0085] The processing system also includes a pressure-reducing tank 8 located downstream of the preheater 3, which is connected to the preheater 3.

[0086] The processing system also includes a catalyst recovery unit located downstream of the pressure reducing tank 8, which is connected to the liquid phase outlet of the pressure reducing tank 8. For example, the catalyst recovery unit is selected from the membrane assembly 9 in a membrane filtration catalyst recovery device for a wet oxidation process disclosed in CN219441259U.

[0087] The processing system also includes a brine buffer unit located downstream of the catalyst recovery unit, which is connected to the liquid phase outlet of the catalyst recovery unit. For example, the brine buffer unit is a brine buffer tank 11.

[0088] The processing system also includes a catalyst regeneration unit located downstream of the catalyst recovery unit, which is connected to the solid phase outlet of the catalyst recovery unit.

[0089] Example 2

[0090] In the treatment system of Example 1 (wherein: throat pipe 507 is a straight tube, the ratio of the diameter of throat pipe 507 to the diameter of the inlet end of the narrowing pipe 506 is 0.2; the ratio of the diameter of throat pipe 507 to the diameter of the outlet end of the expanding pipe 508 is 0.2; micron-sized sieve holes are opened on the gas distribution pipe 505, the pore size of the micron-sized sieve holes is 1μm; the ratio of the diameter of the gas distribution pipe 505 to the diameter of the straight section of the inner swirl cylinder 511 is 0.2; the width of the guide slit 509 is 5mm; the ratio of the width of the guide spiral 504 to the inner diameter of the inner swirl cylinder 511 is 0.2, and there is a certain distance between the guide spiral 504 and the gas distribution pipe 505, the maximum distance between the guide spiral 504 and the gas distribution pipe 505 is 0.2 to the diameter of the inner swirl cylinder 511), the wastewater from the production of epichlorohydrin (with a sodium chloride content of 21wt% and a TOC concentration of...) is treated. A copper chloride solution was added to the wastewater as a catalyst to reduce the copper ion concentration in the wastewater to 1500 mg / L (presumably 2800 mg / L). Concentrated hydrochloric acid was added to adjust the pH of the wastewater to 1. The wastewater then entered a preheater and exchanged heat with the oxidized brine discharged from the catalytic wet oxidation reactor 6 (the temperature of the wastewater after heat exchange reached 200℃). The wastewater then entered a heater to be heated to 240℃. The wastewater and the first stream of oxygen simultaneously entered the vortex bubble generator 5 through gas inlet 503, generating micro-nano bubbles at a flow rate of 2 g / L. This oxygen then entered the catalytic wet oxidation reactor 6. Another stream of oxygen entered the oxidation reactor 6 through the aeration disc at the bottom in the form of millimeter-sized bubbles (2-5 mm) at a flow rate of 5 g / L. The oxidation reaction proceeded at a maximum temperature of 260℃, a residence time of 2 hours, and a reaction pressure of 4.9 MPa. Catalytic wet oxidation brine was obtained.

[0091] A 20% sodium hydroxide solution was added to the catalytic wet oxidation brine to adjust the pH of the brine to 11, causing the copper ion catalyst to form a flocculent copper hydroxide precipitate. The catalyst precipitate was recovered using the filter membrane assembly 9 (the filter membrane used was an ePTFE membrane with a pore size of 0.2 μm). After being dissolved in hydrochloric acid, the precipitate was returned to the reactor for reuse, resulting in catalytic wet oxidation refined brine (TOC concentration of 7.7 mg / L).

[0092] The working principle of the vortex bubble generator 5 is as follows:

[0093] Liquid enters the inlet area through the first liquid inlet 501 and the second liquid inlet 502. It forms a vortex through the guide slit 509 and enters the vortex area. The vortex effect is further enhanced by the guide spiral 504. Gas enters through the gas inlet 503. After being cut by the sieve holes on the gas distribution pipe 505, it forms small bubbles that mix with the liquid. The gas-liquid mixture passes through the narrowing pipe 506 section, which increases the pressure and flow rate at the throat pipe 507 section. It is fully mixed at the throat pipe 507 section and then enters the expanding pipe 508 section for discharge, forming a large number of micron-sized small bubbles.

[0094] Example 3

[0095] In the treatment system of Example 1 (wherein: throat pipe 507 is a straight tube, the ratio of the diameter of throat pipe 507 to the diameter of the inlet end of the narrowing pipe 506 is 0.16; the ratio of the diameter of throat pipe 507 to the diameter of the outlet end of the expanding pipe 508 is 0.16; micron-sized sieve holes are opened on the gas distribution pipe 505, the pore size of the micron-sized sieve holes is 0.5μm; the ratio of the diameter of the gas distribution pipe 505 to the diameter of the straight section of the inner swirl cylinder 511 is 0.3; the width of the guide slit 509 is 3mm; the ratio of the width of the guide spiral 504 to the inner diameter of the inner swirl cylinder 511 is 0.2, there is a certain distance between the guide spiral 504 and the gas distribution pipe 505, and the ratio of the maximum distance between the guide spiral 504 and the gas distribution pipe 505 to the diameter of the inner swirl cylinder 511 is 0.15), the wastewater from the production of epichlorohydrin (with a sodium chloride content of 21wt%, TOC) is treated. A copper chloride solution (with a concentration of 2800 mg / L) is added to the wastewater as a catalyst to achieve a copper ion concentration of 1500 mg / L. Concentrated hydrochloric acid is added to adjust the pH of the wastewater to 1. The wastewater then enters a preheater and exchanges heat with the brine discharged from the catalytic wet oxidation reactor 6 (the temperature of the wastewater after heat exchange reaches 200℃). It then enters a heater to be heated to 240℃. The wastewater and the first stream of oxygen simultaneously enter the vortex bubble generator 5 through gas inlet 503, generating micro-nano bubbles at a flow rate of 2 g / L. This oxygen then enters the catalytic wet oxidation reactor 6. Another stream of oxygen enters the reactor 6 through the bottom aeration disc as millimeter-sized bubbles (2-5 mm) at a flow rate of 5 g / L. The oxidation reaction takes place at a maximum temperature of 260℃, a residence time of 2 hours, and a reaction pressure of 4.9 MPa. Catalytic wet oxidation brine is obtained.

[0096] A 20% sodium hydroxide solution was added to the catalytic wet oxidation brine to adjust the pH of the brine to 11, causing the copper ion catalyst to form a flocculent copper hydroxide precipitate. The catalyst precipitate was recovered using the filter membrane assembly 9 (the filter membrane used was an ePTFE membrane with a pore size of 0.2 μm). After being dissolved in hydrochloric acid, the precipitate was returned to the reactor for reuse, resulting in catalytic wet oxidation refined brine (TOC concentration of 4.3 mg / L).

[0097] Example 4

[0098] In the treatment system of Example 1 (wherein: throat pipe 507 is a straight tube, the ratio of the diameter of throat pipe 507 to the diameter of the inlet end of the narrowing pipe 506 is 0.24; the ratio of the diameter of throat pipe 507 to the diameter of the outlet end of the expanding pipe 508 is 0.24; micron-sized sieve holes are opened on the gas distribution pipe 505, the pore size of the micron-sized sieve holes is 2μm; the ratio of the diameter of the gas distribution pipe 505 to the diameter of the straight section of the inner swirl cylinder 511 is 0.15; the width of the guide slit 509 is 8mm; the ratio of the width of the guide spiral to the inner diameter of the inner swirl cylinder is 0.125; there is a certain distance between the guide spiral 504 and the gas distribution pipe 505, and the ratio of the maximum distance between the guide spiral 504 and the gas distribution pipe 505 to the diameter of the inner swirl cylinder 511 is 0.3), the wastewater from the production of epichlorohydrin (with a sodium chloride content of 21wt% and a TOC concentration of...) is treated. Copper chloride solution was added to the wastewater as a catalyst to achieve a copper ion concentration of 1500 mg / L. Concentrated hydrochloric acid was added to adjust the pH of the wastewater to 1. The wastewater then entered a preheater and exchanged heat with the brine discharged from the catalytic wet oxidation reactor 6 (the temperature of the wastewater after heat exchange reached 200℃). The wastewater then entered a heater to be heated to 240℃. The wastewater and the first stream of oxygen simultaneously entered the vortex bubble generator 5 through gas inlet 503, generating micro-nano bubbles at a flow rate of 2 g / L. This oxygen then entered the catalytic wet oxidation reactor 6. Another stream of oxygen entered the reactor 6 through the bottom aeration disc in the form of millimeter-sized bubbles (2-5 mm) at a flow rate of 5 g / L. The oxidation reaction proceeded at a maximum temperature of 260℃, a residence time of 2 hours, and a reaction pressure of 4.9 MPa. Catalytic wet oxidation brine was obtained.

[0099] A 20% sodium hydroxide solution was added to the catalytic wet oxidation brine to adjust the pH of the brine to 11, causing the copper ion catalyst to form a flocculent copper hydroxide precipitate. The catalyst precipitate was recovered using the filter membrane assembly 9 (the filter membrane used was an ePTFE membrane with a pore size of 0.2 μm). After being dissolved in hydrochloric acid, the precipitate was returned to the reactor for reuse, resulting in catalytic wet oxidation refined brine (TOC concentration of 9.2 mg / L).

[0100] Comparative Example 1

[0101] In the treatment system of Example 1 (wherein: throat pipe 507 is a straight tube, the ratio of the diameter of throat pipe 507 to the diameter of the inlet end of the narrowing pipe 506 is 0.35; the ratio of the diameter of throat pipe 507 to the diameter of the outlet end of the expanding pipe 508 is 0.35; micron-sized sieve holes are opened on the gas distribution pipe 505, the pore size of the micron-sized sieve holes is 5μm; the ratio of the diameter of the gas distribution pipe 505 to the diameter of the straight section of the inner swirl cylinder 511 is 0.1; the width of the guide slit 509 is 15mm; the ratio of the width of the guide spiral 509 to the inner diameter of the inner swirl cylinder 511 is 0.05; there is a certain distance between the guide spiral 504 and the gas distribution pipe 505, and the maximum distance between the guide spiral 504 and the gas distribution pipe 505 is 0.4 to the diameter of the inner swirl cylinder 511), the wastewater from the production of epichlorohydrin (with a sodium chloride content of 21wt%, TOC) is treated. A copper chloride solution (with a concentration of 2800 mg / L) is added to the wastewater as a catalyst to achieve a copper ion concentration of 1500 mg / L. Concentrated hydrochloric acid is added to adjust the pH of the wastewater to 1. The wastewater then enters a preheater and exchanges heat with the brine discharged from the catalytic wet oxidation reactor 6 (the temperature of the wastewater after heat exchange reaches 200℃). It then enters a heater to be heated to 240℃. The wastewater and the first stream of oxygen simultaneously enter the vortex bubble generator 5 through gas inlet 503, generating micro-nano bubbles at a flow rate of 2 g / L. This oxygen then enters the catalytic wet oxidation reactor 6. Another stream of oxygen enters the reactor 6 through the bottom aeration disc as millimeter-sized bubbles (2-5 mm) at a flow rate of 5 g / L. The oxidation reaction takes place at a maximum temperature of 260℃, a residence time of 2 hours, and a reaction pressure of 4.9 MPa. Catalytic wet oxidation brine is obtained.

[0102] A 20% sodium hydroxide solution was added to the catalytic wet oxidation brine to adjust the pH of the brine to 11, causing the copper ion catalyst to form a flocculent copper hydroxide precipitate. The catalyst precipitate was recovered using the filter membrane assembly 9 (the filter membrane used was an ePTFE membrane with a pore size of 0.2 μm). After being dissolved in hydrochloric acid, the precipitate was returned to the reactor for reuse, resulting in catalytic wet oxidation refined brine (TOC concentration of 16.1 mg / L).

[0103] Comparative Example 2

[0104] In the treatment system of Example 1 (wherein: throat pipe 507 is a straight tube, the ratio of the diameter of throat pipe 507 to the diameter of the inlet end of the narrowing pipe 506 is 0.1; the ratio of the diameter of throat pipe 507 to the diameter of the outlet end of the expanding pipe 508 is 0.1; micron-sized sieve holes are opened on the gas distribution pipe 505, the pore size of the micron-sized sieve holes is 1μm; the ratio of the diameter of the gas distribution pipe 505 to the diameter of the straight section of the inner swirl cylinder 511 is 0.6; the width of the guide slit 509 is 2mm; the ratio of the width of the guide spiral 504 to the inner diameter of the inner swirl cylinder 511 is 0.1, there is a certain distance between the guide spiral 504 and the gas distribution pipe 505, and the maximum distance between the guide spiral 504 and the gas distribution pipe 505 is 0.1 to the diameter of the inner swirl cylinder 511), the wastewater from the production of epichlorohydrin (with a sodium chloride content of 21wt% and a TOC concentration of...) is treated. A copper chloride solution was added to the wastewater as a catalyst to reduce the copper ion concentration in the wastewater to 1500 mg / L (presumably 2800 mg / L). Concentrated hydrochloric acid was added to adjust the pH of the wastewater to 1. The wastewater then entered a preheater and exchanged heat with the oxidized brine discharged from the catalytic wet oxidation reactor 6 (the temperature of the wastewater after heat exchange reached 200℃). The wastewater then entered a heater to be heated to 240℃. The wastewater and the first stream of oxygen simultaneously entered the vortex bubble generator 5 through gas inlet 503, generating micro-nano bubbles at a flow rate of 2 g / L. This oxygen then entered the catalytic wet oxidation reactor 6. Another stream of oxygen entered the oxidation reactor 6 through the aeration disc at the bottom in the form of millimeter-sized bubbles (2-5 mm) at a flow rate of 5 g / L. The oxidation reaction proceeded at a maximum temperature of 260℃, a residence time of 2 hours, and a reaction pressure of 4.9 MPa. Catalytic wet oxidation brine was obtained.

[0105] A 20% sodium hydroxide solution was added to the catalytic wet oxidation brine to adjust the pH of the brine to 11, causing the copper ion catalyst to form a flocculent copper hydroxide precipitate. The catalyst precipitate was recovered using the filter membrane assembly 9 (the filter membrane used was an ePTFE membrane with a pore size of 0.2 μm). After being dissolved in hydrochloric acid, the precipitate was returned to the reactor for reuse, resulting in catalytic wet oxidation refined brine (TOC concentration of 14.7 mg / L).

[0106] Comparative Example 3

[0107] Wastewater from epichlorohydrin production (containing 21 wt% sodium chloride and 2800 mg / L TOC) was treated with copper chloride solution as a catalyst to achieve a copper ion concentration of 1500 mg / L. Concentrated hydrochloric acid was added to adjust the pH to 1. The wastewater then entered a preheater and exchanged heat with the brine discharged from the catalytic wet oxidation reactor 6 (the temperature of the wastewater after heat exchange reached 200°C). It was then heated to 240°C in a heater before entering the catalytic wet oxidation reactor 6. Oxygen was introduced into the reactor 6 at a rate of 13 g / L through an aeration disc at the bottom in the form of millimeter-sized bubbles (2-5 mm). The oxidation reaction was carried out at a maximum temperature of 260°C, a residence time of 4 hours, and a reaction pressure of 4.9 MPa, yielding catalytic wet oxidation brine.

[0108] A 20% sodium hydroxide solution was added to the catalytic wet oxidation brine to adjust the pH to 11, causing the copper ion catalyst to form a flocculent copper hydroxide precipitate. The catalyst precipitate was recovered using filter membrane assembly 9 (using an ePTFE membrane with a pore size of 0.2 μm), dissolved in hydrochloric acid, and returned to the reactor for reuse, yielding catalytic wet oxidation refined brine (TOC concentration of 19.8 mg / L). The results showed that when all oxygen entered the oxidation reactor 6 in the form of millimeter-sized bubbles, not only did the oxygen consumption increase, but even with extended treatment time, the treatment effect was still worse than that after oxygen oxidation using a large number of micron-sized small bubbles generated by the vortex bubble generator 5.

[0109] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wet oxidation method wastewater treatment system characterized by, It comprises a vortex bubble generator; An oxidation reactor located downstream of the vortex bubble generator; A heater located upstream of the vortex bubble generator; And a preheater located upstream of the heater.

2. The processing system of claim 1, wherein, The vortex bubble generator comprises an outer rotating cylinder, a reduced-diameter pipe, a throat pipe and an expanded-diameter pipe connected in sequence, an inner rotating cylinder is arranged in the outer rotating cylinder, and the center axes of the outer rotating cylinder, the inner rotating cylinder, the reduced-diameter pipe, the throat pipe and the expanded-diameter pipe are on a straight line.

3. The processing system of claim 2, wherein, A liquid inlet is arranged on the side wall of the outer rotating cylinder; And / or, the end of the inner rotating cylinder coincides with or closely fits the end of the outer rotating cylinder; And / or, the outer rotating cylinder and the inner rotating cylinder are fixed by concentric discs; And / or, the end of the inner rotating cylinder is provided with a gas inlet, a vortex area is arranged in the inner rotating cylinder, and the outlet end of the inner rotating cylinder is communicated with the reduced-diameter pipe; And / or, the throat pipe is a straight cylinder pipe, and the ratio of the diameter of the throat pipe to the diameter of the inlet end of the reduced-diameter pipe is 0.16-0.24; And / or, the inlet end of the expanded-diameter pipe is connected with the other end of the throat pipe, and the outlet end of the expanded-diameter pipe is provided with a gas-liquid combined outlet; And / or, the ratio of the diameter of the throat pipe to the diameter of the outlet end of the expanded-diameter pipe is 0.16-0.24; And / or, a gas distribution pipe is arranged in the inner rotating cylinder, and the gas distribution pipe is coaxial with the inner rotating cylinder; And / or, micron-level sieve holes are arranged on the gas distribution pipe, and the aperture of the micron-level sieve holes is 0.5-2 μm; And / or, the ratio of the diameter of the gas distribution pipe to the diameter of the straight cylinder segment of the inner rotating cylinder is 0.15-0.35; And / or, a flow guide spiral is arranged on the gas distribution pipe in the axial direction; And / or, the flow guide spiral is connected with the inner wall of the inner rotating cylinder; And / or, the ratio of the width of the flow guide spiral to the inner diameter of the inner rotating cylinder is 0.1-0.2; And / or, the inner rotating cylinder is assembled by four arc-shaped plates, and a flow guide gap is formed between the adjacent two arc-shaped plates; And / or, the width of the flow guide gap is 3-10 mm; And / or, the flow guide spiral has a certain distance from the inner wall of the inner rotating cylinder; And / or, the ratio of the maximum distance between the flow guide spiral and the gas distribution pipe to the diameter of the inner rotating cylinder is 0.125-0.

325.

4. The processing system according to any one of claims 1-3, characterized by The oxidation reactor further comprises elements required for catalytic wet oxidation reaction, which include but are not limited to one or more selected from the group consisting of a gas inlet unit, a gas outlet unit, a feed unit, a discharge unit and an instrument unit; The feed unit is connected with the outlet end of the expanded-diameter pipe of the vortex bubble generator.

5. The processing system according to any one of claims 1-3, characterized by, The treatment system further comprises a high-pressure pump located upstream of the preheater; And / or, the treatment system further comprises a wastewater storage unit located upstream of the high-pressure pump.

6. The processing system according to any one of claims 1-3, wherein, The treatment system further comprises a pressure reduction tank located downstream of the preheater, and the pressure reduction tank is connected with the preheater; And / or, the treatment system further comprises a catalyst recovery unit located downstream of the pressure reduction tank, and the catalyst recovery unit is connected with the liquid phase outlet of the pressure reduction tank.

7. The processing system according to any one of claims 1-3, wherein, The treatment system further comprises a fine brine buffer unit located downstream of the catalyst recovery unit, and the fine brine buffer unit is connected with the liquid phase outlet of the catalyst recovery unit; And / or, the processing system further comprises a catalyst regeneration unit downstream of the catalyst recovery unit, which is connected to the solid phase outlet of the catalyst recovery unit.

8. A method of wastewater treatment, characterized by, The wastewater is made to react with oxygen in the vortex bubble generator to form wastewater containing oxygen micro-nano bubbles, and then enters the oxidation reactor to perform catalytic wet oxidation reaction, thereby achieving wastewater purification.

9. The method of claim 8, wherein, The median particle size D of the micro-nano bubbles containing oxygen 50 is 20-40 μm; And / or, the method comprises pressurizing the wastewater in the wastewater storage unit by a high-pressure pump, preheating the wastewater in the preheater, heating the wastewater in the heater, making the wastewater react with oxygen in the vortex bubble generator to form wastewater containing oxygen micro-nano bubbles, and performing catalytic wet oxidation reaction in the oxidation reactor, thereby achieving wastewater purification.

10. The method according to claim 8 or 9, characterized in that, The flow rate ratio of oxygen entering the gas distribution pipe through the gas inlet to oxygen entering the oxidation reactor through the gas inlet unit is 1:2-7; And / or, the operating temperature of the reactor is 150-280 DEG C, and the pressure of the reactor is 4-7 MPa; And / or, the pH value of the wastewater during the catalytic wet oxidation reaction is 0.8-1.4; And / or, the catalyst used in the catalytic wet oxidation reaction is a copper ion-containing catalyst, and the content of copper ions is 1000-3000 ppm.

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