Device and method for purifying and recycling methanol-to-aromatic hydrocarbon generated water

Abstract

The invention provides a device and method for purifying and recycling methanol-to-aromatic hydrocarbon generated water, and relates to the technical field of methanol-to-aromatic hydrocarbon generated water treatment.The method comprises the steps that the generated water is subjected to steam stripping separation through a steam stripping tower, and oxygen-containing compounds in liquid-phase components enter a concentrated water recycling system; purified water at the bottom of the tower enters an electric flocculation reactor after being subjected to temperature regulation through a heat exchanger and an air cooler, and dissolved pollutants are converted into flocculated particles; then deeply separating by a radial micro-channel separator and entering reverse osmosis equipment to remove residual COD (Chemical Oxygen Demand), recycling reverse osmosis produced water to the quench tower / water scrubber, and recycling concentrated water to a concentrated water recycling system. The device comprises a stripping tower, a first delivery pump, an air cooler, a heat exchanger, an electric flocculation reactor, a radial microchannel separator, a second delivery pump and reverse osmosis equipment, through step-by-step load reduction cooperative treatment of electric flocculation-radial microchannel-reverse osmosis, membrane pollution is inhibited, water resource recycling is achieved, and the water resource utilization rate is increased.

Description

Technical Field

[0001] This invention relates to the technical field of water treatment generated from methanol-to-aromatics production, and particularly to an apparatus and method for purifying and reusing water generated from methanol-to-aromatics production. Background Technology

[0002] Methanol-to-aromatics (MTO) technology is a chemical process that uses methanol as a raw material (produced via coal-based or natural gas-based routes) to synthesize aromatic products such as benzene, toluene, and xylene (BTX) through a series of catalytic reactions including dehydration, carbon chain growth, cyclization, and dehydrogenation, under the action of an acidic molecular sieve catalyst (such as modified ZSM-5). The reaction water produced by this process has a complex composition of pollutants, mainly including oxygen-containing organic matter (such as methanol and formaldehyde), colloidal substances, suspended solids, and recalcitrant organic components. Direct discharge or reuse without proper treatment will not only lead to serious water waste and environmental pollution but may also affect the stable operation of subsequent process units and product quality. Currently, industrial applications primarily employ deep purification processes that combine physical oil removal (such as air flotation-ceramic membrane co-processing), chemical oxidation (ozone catalysis), and biological filters (BAF) coupled with reverse osmosis. However, these processes still face several technical bottlenecks: separation difficulties due to oil-phase emulsification, equipment blockage caused by the condensation of aldehydes and ketones, water quality fluctuations (sulfide fixation effect and catalyst fine powder impact), difficulty in meeting COD and sulfide standards in purified water, corrosion risks in reclaimed water, and the economic viability of high-cost deep treatment processes. To address these challenges, there is an urgent need to develop efficient water treatment technologies to simultaneously remove particulate matter, dissolved organic matter, and non-dissolved organic components from water.

[0003] Chinese patent publication number CN103755087A discloses a system and method for treating methanol aromatization process wastewater. It uses a combination of high-temperature stripping device, carbon medium absorption device, and anion exchange system to treat methanol aromatization process wastewater, which can remove organic acids from the wastewater. However, the treated wastewater is difficult to meet the reuse standards.

[0004] Chinese patent publication number CN104150673A discloses a system and method for treating and reusing methanol aromatization wastewater. The wastewater is first separated by a gas-liquid-solid three-phase separator, and then sequentially passes through a particle removal device, a stripping device, an oil removal device, and an air flotation device. Finally, it is treated in conjunction with a biochemical system. The final discharged wastewater can meet the reuse standards, and some of the wastewater can be reused as cooling water. However, the system is complex to control, has high energy consumption, and high equipment costs. Although it achieves partial wastewater reuse, the treatment process is complex and costly.

[0005] Chinese patent publication number CN106517642A discloses a method for zero-discharge treatment of wastewater in a methanol-to-aromatics plant. The method first pre-treats the production wastewater, emergency pool water, and domestic sewage in the plant area through neutralization, oil separation, and adjustment. Then, it removes suspended solids and organic matter through processes such as air flotation, anaerobic, aerobic, and MBR. Finally, it disinfects and discharges the wastewater to achieve zero discharge. However, the treatment process is not precise enough for the treatment of specific pollutants in the generated water.

[0006] Existing processes are not ideal for treating oxygen-containing compounds (such as alcohols and aldehydes), macromolecular organic matter, colloidal particles, and suspended solids. The water generated from methanol-to-aromatics production is not effectively utilized, which not only causes serious waste of water resources but also has adverse effects on the ecological environment. At the same time, with increasingly stringent environmental standards and the aggravation of water shortage problems, how to achieve the purification and reuse of this type of generated water at low cost has become a technical problem that the industry urgently needs to solve. Therefore, it is necessary to provide a method and apparatus for purifying and reusing water generated from methanol-to-aromatics production to solve the above-mentioned technical problems. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the present invention provides an apparatus and method for purifying and reusing water generated from methanol-to-aromatics production.

[0008] The present invention provides a device for purifying and reusing water generated from methanol-to-aromatics production, comprising a stripping tower, a first transfer pump, a heat exchanger, an air cooler, an electrocoagulation reactor, a radial microchannel separator, a second transfer pump, and a reverse osmosis device connected in sequence by pipelines; wherein the electrocoagulation reactor, the radial microchannel separator, and the reverse osmosis device constitute a synergistic treatment unit with progressively reduced load, used to reduce the risk of membrane fouling and stabilize the quality of the reclaimed water.

[0009] The bottom outlet of the stripping tower is connected to the inlet of the first transfer pump, the outlet of the second transfer pump is connected to the inlet of the reverse osmosis equipment, and the top outlet of the reverse osmosis equipment is connected to the inlet of the external quench tower and water washing tower. The top outlet of the stripping tower and the bottom outlet of the reverse osmosis equipment are connected to an external concentrated water recovery system, and the reverse osmosis permeate is reused in the quench tower and the water washing tower.

[0010] Furthermore, a sedimentation tank connected to its outlet is installed at the bottom of the electrocoagulation reactor, and the outlet of the sedimentation tank is connected to the inlet of the radial microchannel separator.

[0011] Furthermore, the anode of the electrocoagulation reactor is made of stainless steel, and the cathode is made of carbon plate.

[0012] Furthermore, a three-phase cyclone separator is mounted on top of the radial microchannel separator.

[0013] Furthermore, the radial microchannel separator is equipped with a multi-stage separation module and a self-cleaning backwashing device.

[0014] Furthermore, the multi-stage separation module adopts a three-stage separation module, wherein the first-stage separation module adopts a honeycomb microchannel array, the second-stage separation module adopts a ceramic filter element, and the third-stage separation module adopts an ultrafiltration membrane assembly.

[0015] Furthermore, the reverse osmosis membrane active separation layer in the reverse osmosis equipment contains a cross-linked network structure, and the reverse osmosis equipment adopts a branched flow membrane stack structure.

[0016] Based on the above solution, the present invention also provides a method for purifying and reusing water generated from methanol-to-aromatics production, comprising the following steps: S1: The water generated from methanol-to-aromatics production is transported to a stripping tower for cooling, so that the oxygen-containing compounds in the liquid phase of the generated water are separated to the concentrated water recovery system. The purified water discharged from the bottom outlet of the stripping tower enters the heat exchanger and air cooler in sequence for heat exchange and temperature regulation. S2: The purified water discharged from the heat exchanger enters the electrocoagulation reactor for oxidation-reduction treatment, and the colloidal pollutants in the purified water are precipitated and separated. S3: The purified water discharged from the electrocoagulation reactor enters the radial microchannel separator to perform deep separation of suspended particles, so as to obtain purified water with low suspended solids load. S4: The purified water discharged from the radial microchannel separator enters the reverse osmosis equipment to remove COD. The reverse osmosis permeate is reused in the quench tower and water washing tower, and the concentrate enters the concentrate recovery system.

[0017] Furthermore, the oil content of the purified water treated in step S4 is reduced to 0.2 mg / L, and the turbidity is reduced to 1 NTU.

[0018] Furthermore, the pH value in the electrocoagulation reactor is 7-8, and the current intensity is 15-35 mA / cm²; the operating pressure of the radial microchannel separator is 0.1-0.3 MPa, and the flow rate is 0.8-1.5 m / s; the operating pressure of the reverse osmosis equipment is 1.5-4.0 MPa.

[0019] Compared with related technologies, the apparatus and method for purifying and reusing water generated from methanol-to-aromatics production provided by the present invention have the following beneficial effects: 1. This invention utilizes stripping pre-separation to centrally introduce low-molecular-weight oxygenated compounds (such as methanol, formaldehyde, aldehydes, and ketones) from the top of the stripping tower into the concentrated water recovery system, reducing the load on subsequent treatments and avoiding interference with the electrochemical and membrane separation units. Simultaneously, the temperature of the purified water at the bottom of the tower is controlled via heat exchangers and air coolers, allowing the electrocoagulation reactor to undergo redox reactions under suitable conditions. The electrocoagulation reactor converts dissolved organic matter and colloidal pollutants into flocculated particles and achieves co-precipitation separation. The radial microchannel separator deeply intercepts flocculated particles and fine suspended solids, forming a synergistic treatment unit with the reverse osmosis equipment to progressively reduce the load on suspended solids / colloids and the tendency for fouling in the water entering the reverse osmosis equipment, inhibiting membrane fouling at the source and stabilizing the quality of reclaimed water. Furthermore, this synergistic unit reduces the fouling load upstream, bringing the feed water to the reverse osmosis equipment closer to stable operating conditions, thereby lowering the probability of triggering the membrane fouling threshold.

[0020] 2. The multi-stage separation module of the radial microchannel separator achieves gradient interception. The self-cleaning backwashing device automatically removes trapped pollutants through air-water mixing backwashing. Combined with the rotating turbulent flow field formed by the top three-phase hydrocyclone, it realizes the regeneration of the separation medium and bed reconstruction, reducing clogging and pressure drop accumulation, providing stable feed water for the reverse osmosis equipment and reducing the fluctuation of the fouling index. The active separation layer of the reverse osmosis membrane contains a cross-linked network structure and is combined with a branched flow membrane stack structure, which can delay flux decay, reduce cleaning frequency and improve long-term operational stability.

[0021] 3. The purified water treated by the reverse osmosis equipment is reused in the quench tower and water washing tower, and the concentrated water is returned to the concentrated water recovery system, forming a closed loop of treatment, reuse, concentration and recovery, which greatly improves the utilization rate of water resources, reduces the amount of fresh water taken from industry and the amount of sewage discharged. Oxygen-containing compounds and concentrated water are uniformly entered into the concentrated water recovery system to achieve centralized treatment of pollutants, reduce the cost of decentralized treatment, and meet the requirements of clean production and environmental protection. Attached Figure Description

[0022] Figure 1 A schematic diagram of the connection structure of the methanol-to-aromatics water purification and reuse device provided by the present invention. Figure 2 This is a schematic diagram of the process flow for purifying and reusing water generated from methanol-to-aromatics production in this invention. Figure 3 This is a schematic diagram of the self-cleaning backwashing device connected to the radial microchannel separator in this invention; Figure 4 This is a schematic diagram of the internal structure of the radial microchannel separator in this invention.

[0023] Labels in the diagram: 1. Stripping tower; 2. First transfer pump; 3. Heat exchanger; 4. Air cooler; 5. Electrocoagulation reactor; 6. Radial microchannel separator; 7. Second transfer pump; 8. Reverse osmosis equipment; 9. Three-phase hydrocyclone; 10. Backwash inlet; 11. Backwash outlet; 12. Exhaust port; 13. Return water port; 14. Air pump; 15. Centrifugal pump; 16. Clear water tank. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Example 1: Please refer to the following: Figure 1 , Figure 3 as well as Figure 4 As shown, this invention discloses a device for purifying and reusing water generated from methanol-to-aromatics production, comprising a stripping tower 1, a first transfer pump 2, a heat exchanger 3, an air cooler 4, an electrocoagulation reactor 5, a radial microchannel separator 6, a second transfer pump 7, and a reverse osmosis unit 8. The top outlet of the stripping tower 1 is connected to the inlet of an external concentrated water recovery system via a pipeline, the bottom outlet of the stripping tower 1 is connected to the inlet of the first transfer pump 2 via a pipeline, the outlet of the first transfer pump 2 is connected to the inlet of the heat exchanger 3 via a pipeline, and the outlet of the heat exchanger 3 is connected to the air cooler via a pipeline. The inlet of air cooler 4 is connected to the outlet of air cooler 4 via a pipe. The outlet of air cooler 4 is connected to the inlet of electrocoagulation reactor 5 via a pipe. The outlet of electrocoagulation reactor 5 is connected to the inlet of radial microchannel separator 6 via a pipe. The outlet of radial microchannel separator 6 is connected to the inlet of second transfer pump 7 via a pipe. The outlet of second transfer pump 7 is connected to the inlet of reverse osmosis equipment 8. The top outlet of reverse osmosis equipment 8 is connected to the inlet of external quench tower and water washing tower via a pipe. The bottom outlet of reverse osmosis equipment 8 is connected to external concentrated water recovery system via a pipe. The stripping tower 1 is used to remove oxygenated compounds from the water produced by methanol-to-aromatics production. The oxygenated compounds in the water produced by methanol-to-aromatics production enter the concentrated water recovery system from the top outlet of the stripping tower 1. The purified water discharged from the bottom outlet of the stripping tower 1 enters the electrocoagulation reactor 5 after heat exchange. The electrocoagulation reactor 5 is used to remove colloidal particles, macromolecular organic matter, and some suspended solids. The radial microchannel separator 6 is used to achieve submicron-level particle separation and partial desalination for deep treatment. The reverse osmosis equipment 8 is used to deeply remove residual organic pollutants. Part of the treated purified water enters the quench tower and water washing tower for reuse. In this embodiment, a sedimentation tank connected to the outlet of the electrocoagulation reactor 5 is installed at the bottom of the reactor. The outlet of the sedimentation tank is connected to the inlet of the radial microchannel separator 6. The sedimentation tank can initially settle the flocculated material in the purified water after passing through the electrocoagulation reactor 5, pre-separate larger flocculated material, reduce the load on the radial microchannel separator 6, and avoid clogging of the separated coal in the radial microchannel separator 6. At the same time, through preliminary sedimentation and deep separation, the overall suspended solids removal efficiency is improved, ensuring the water quality of the inlet water of the subsequent reverse osmosis equipment 8. Preferably, the anode of the electrocoagulation reactor 5 is made of 316L stainless steel, and the cathode is made of carbon steel. The 316L stainless steel anode has excellent corrosion resistance and is suitable for highly polluted water environments. The effective volume of the reaction tank in the electrocoagulation reactor 5 is 60m³, the number of electrode plates is 10-20 pairs, the electrode plate spacing is 30-50mm, the current density is 10-20mA / cm², and the electrode plate life is not less than 5000 hours. A large number of three-dimensional particle electrodes are filled at the electrode plate spacing. The three-dimensional particle electrodes increase the reaction area and enhance the electrocatalytic effect. A scraper is installed at the top of the reaction tank to ensure timely removal of floating flocs. The scraper and sedimentation tank can prevent secondary suspension of flocs, improve solid-liquid separation efficiency, and ensure the quality of the effluent. Specifically, a chain and sprocket mechanism is installed at the top of the reaction tank, and a scraper is installed on the chain. A collection tank installed on the reaction tank is set at one end of the chain and sprocket mechanism. Driven by the chain, the scraper will pass through the edge of the collection tank and scrape the flocculent on the scraper into the collection tank.

[0026] In this embodiment, a three-phase cyclone separator 9 is installed on the top of the radial microchannel separator 6; the rotating turbulent field formed in the three-phase cyclone separator 9 can enhance the regeneration effect of the separated coal in the radial microchannel separator 6, and at the same time realize the in-situ recovery of coal particles and bed reconstruction. Preferably, the radial microchannel separator 6 is equipped with a multi-stage separation module, and the radial microchannel separator 6 is also connected to a self-cleaning backwashing device; the self-cleaning backwashing device automatically removes trapped pollutants through reverse pulse flushing, maintaining the high efficiency of coal separation and reducing manual intervention; in this embodiment, the multi-stage separation module adopts a three-stage separation module, wherein the first-stage separation module adopts a honeycomb microchannel array to remove particles larger than 10μm, the second-stage separation module adopts a ceramic filter element to remove particles larger than 5μm, and the third-stage separation module adopts an ultrafiltration membrane module to remove particles larger than 1μm. The pressure drop of each stage is 0.03MPa, and the separation media of multiple particle size ranges realize the interception of particles of various gradients in the purified water; moreover, the combined design of coal separation and three-phase hydrocyclone 9 realizes the integrated function of high-efficiency separation and coal regeneration; Specifically, such as Figure 3 and Figure 4As shown, a multi-stage separation module is located in the middle of the radial microchannel separator 6; a backwash inlet 10 is installed at the bottom of the radial microchannel separator 6, and the outlet is installed on the side of the radial microchannel separator 6. A backwash outlet 11 connected to the outside is connected to the three-phase hydrocyclone 9, and an exhaust port 12 and a return water port 13 are opened at the top of the three-phase hydrocyclone 9; an air pump 14 and a centrifugal pump 15 are installed outside the radial microchannel separator 6. The centrifugal pump 15 is connected to a clean water tank 16, the air pump 14 is connected to a buffer tank, and the outlet of the pressure stabilizing tank is connected to an air pump. The centrifugal pump 15 has an outlet connected to an inlet pipe. An air pipe and the inlet pipe converge and connect to the backwash inlet 10. A return water pipe connected to the inlet pipe is located at the return water outlet 13. When backwashing is required, the centrifugal pump 15 and the air pump 14 are turned on, allowing clean water and compressed air to mix and enter the radial microchannel separator 6 from the backwash inlet 10. Air is released from the exhaust port 12, and clean wastewater is discharged from the backwash outlet 11. The return water from the return water outlet 13 circulates with the clean water back to the backwash inlet 10 and enters the radial microchannel separator 6. Control valves are installed on the inlet pipe, air pipe, and return water pipe.

[0027] In this embodiment, the reverse osmosis membrane active separation layer in the reverse osmosis equipment 8 contains a cross-linked network structure to achieve the interception and removal of pollutants. The reverse osmosis equipment 8 adopts a branch flow membrane stack structure. The membrane stack is designed through branch flow theory, which reduces the risk of membrane fouling by eliminating backflow shutdown, improves the stability of long-term operation of the equipment, and reduces maintenance frequency and operating costs. Its high-efficiency interception capacity can reduce pollutants such as oil and suspended solids to extremely low levels, so that the purified water meets the industrial reuse standards and meets the water requirements of quench towers and water washing towers.

[0028] The working principle of this device is as follows: The water produced from the production of aromatics from alcohols first enters stripping tower 1 for stripping treatment. Utilizing the stripping principle, low-molecular-weight oxygen-containing compounds (alcohols, aldehydes, etc.) in the liquid phase of the produced water are separated from the top outlet of stripping tower 1 and sent to the concentrated water recovery system, achieving centralized removal and recovery of oxygen-containing compounds and reducing the organic load on subsequent electrochemical and membrane separation units. The pre-purified water obtained from the bottom of stripping tower 1 is pressurized by the first transfer pump 2 and sequentially enters heat exchanger 3 and air cooler 4 for heat exchange and air cooling regulation, controlling the water temperature within the suitable process window for the electrocoagulation reaction, and then enters electrocoagulation reactor 5. In electrocoagulation reactor 5, the redox synergy mechanism of stainless steel anode and carbon plate cathode is used to electrochemically convert dissolved organic matter and flocculate colloidal pollutants into flocculent particles. An internal sedimentation tank pre-sedimentes larger flocs, and an upper scraper promptly removes floating flocs to avoid secondary suspension, thereby reducing the transient floc load entering the radial microchannel separator 6. The purified water then enters the radial microchannel separator 6. Inside the separator, multi-stage separation modules perform gradient interception of flocculated particles and fine suspended solids within different particle size ranges. The rotating turbulent flow field formed by the top three-phase hydrocyclone 9 enhances the regeneration of the separation medium and achieves bed reconstruction. The self-cleaning backwashing device automatically removes trapped contaminants through air-water mixed backwashing, jointly maintaining separation efficiency and pressure drop stability, resulting in stable effluent with low turbidity and low colloidal load. This provides low-contamination-risk feed water conditions for the reverse osmosis equipment. During the radial microchannel separation stage, an operating pressure of 0.1-0.3 MPa and a flow rate of 0.8-1.5 m / s can be used to balance separation efficiency and pressure drop stability. The purified water treated by the radial microchannel separator 6 is pressurized and transported to the reverse osmosis unit 8 by the second transfer pump 7. The active separation layer of the reverse osmosis membrane contains a cross-linked network structure and adopts a branched flow membrane stack structure to deeply remove residual organic pollutants (COD) and trace amounts of oil, delay membrane flux decay and reduce the frequency of chemical cleaning. The treated purified water is transported from the top outlet of the reverse osmosis unit 8 to the external quench tower and water washing tower for reuse, while the concentrate at the bottom outlet is returned to the concentrate recovery system, realizing a closed-loop operation of treatment-reuse-concentration recovery.

[0029] Example 2: See Figure 2 Based on the technical solution of Embodiment 1, the present invention also provides a method for purifying and reusing water generated from methanol-to-aromatics production, comprising the following steps: S1: The water generated from methanol to aromatics is transported to stripping tower 1 for stripping treatment, so that the oxygen-containing compounds in the liquid phase component of the generated water are separated to the concentrated water recovery system. The purified water discharged from the bottom outlet of the stripping tower 1 enters heat exchanger 3 and air cooler 4 in sequence for heat exchange and air cooling to regulate the temperature. S2: The purified water discharged from the air cooler 4 enters the electrocoagulation reactor 5 for oxidation-reduction treatment, and the colloidal pollutants in the purified water are precipitated and separated. S3: The purified water discharged from the electrocoagulation reactor 5 enters the radial microchannel separator 6 for deep separation of suspended particles; S4: The purified water discharged through the radial microchannel separator 6 enters the reverse osmosis equipment 8 to remove COD, the product water is reused, and the concentrate is recovered.

[0030] In the above method, the stripping tower 1 separates oxygenated compounds, alcohols, and aldehydes from the methanol-to-aromatics product water from the top outlet to the concentrated water recovery system through the stripping principle, achieving preliminary separation of pollutants and reducing the load on subsequent treatment. The heat exchanger 3 and air cooler 4 regulate the temperature of the purified water, creating suitable reaction conditions for the electrocoagulation reactor 5 and improving the efficiency of subsequent treatment. This staged reduction can reduce the probability of colloids and fine particles entering the reverse osmosis equipment and delay the flux decline.

[0031] In step S1 of this embodiment, the separation function of stripping tower 1 can avoid interference from oxygen-containing compounds such as methanol and formaldehyde to subsequent processing processes, while concentrating and recycling pollutants to improve resource utilization and reduce pollutant emissions. In step S2 of this embodiment, heat exchange is performed through heat exchanger 3 and air cooler 4. After air cooling, the purified water is treated by electrocoagulation, and the organic matter, mainly alcohols and aldehydes, is significantly reduced. Heat exchanger 3 and air cooler 4 adjust the water temperature to the optimal range for electrocoagulation reaction through heat exchange, ensuring that the electrode plate undergoes oxidation-reduction reaction under suitable conditions, maximizing the degradation of organic matter such as alcohols and aldehydes, and improving the water purification effect.

[0032] In step S3 of this embodiment, after deep processing by the radial microchannel separator 6, the suspended matter is effectively removed.

[0033] In the above-mentioned radial microchannel separator 6, the three-stage separation module and self-cleaning backwashing device can continuously and efficiently remove suspended solids of different particle sizes. At the same time, the rotating turbulent flow field of the top three-phase hydrocyclone 9 realizes the regeneration of the separation medium and the reconstruction of the bed, extending the equipment operation cycle and reducing maintenance costs.

[0034] In this embodiment, the oil content of the purified water treated in step S4 is reduced to 0.2 mg / L and the turbidity is reduced to 1 NTU, so that the purified water meets the industrial reuse standard and meets the water requirements of the quench tower and the water washing tower. In this embodiment, the pH value of the electrocoagulation reactor 5 is 7-8, and the current intensity is 15-35 mA / cm²; the operating pressure of the radial microchannel separator 6 is 0.1-0.3 MPa, and the flow rate is 0.8-1.5 m / s; the operating pressure of the reverse osmosis equipment is 1.5-4.0 MPa. The pH and current intensity parameters of the electrocoagulation reactor 5 are optimized to ensure the stability of the electrochemical performance of the electrode plates and promote the efficient flocculation reaction; the pressure and flow rate parameters of the radial microchannel separator 6 balance the separation efficiency and energy consumption; the operating pressure of the reverse osmosis equipment 8 is adapted to the membrane element performance, ensuring the pollutant rejection rate while reducing membrane module wear.

[0035] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A device for purifying and reusing water generated from methanol-to-aromatics production, characterized in that: It includes a stripping tower (1), a first transfer pump (2), a heat exchanger (3), an air cooler (4), an electrocoagulation reactor (5), a radial microchannel separator (6), a second transfer pump (7), and a reverse osmosis device (8), with each component connected in sequence by pipelines; The bottom outlet of the stripping tower (1) is connected to the inlet of the first transfer pump (2), the outlet of the second transfer pump (7) is connected to the inlet of the reverse osmosis equipment (8), and the top outlet of the reverse osmosis equipment (8) is connected to the inlet of the external quench tower and / or water washing tower. The top outlet of the stripping tower (1) and the bottom outlet of the reverse osmosis equipment (8) are connected to the external concentrated water recovery system; wherein, the electrocoagulation reactor (5), the radial microchannel separator (6) and the reverse osmosis equipment (8) constitute a graded load reduction and synergistic treatment unit to suppress reverse osmosis membrane fouling and improve the stability of reclaimed water quality.

2. The apparatus for purifying and reusing water generated from methanol-to-aromatics production according to claim 1, characterized in that: The bottom of the electrocoagulation reactor (5) is equipped with a sedimentation tank connected to its outlet. The outlet of the sedimentation tank is connected to the inlet of the radial microchannel separator (6). The sedimentation tank is used to pre-sediment the flocculated particles to reduce the transient floc load.

3. The apparatus for purifying and reusing water generated from methanol-to-aromatics production according to claim 1 or 2, characterized in that: The anode of the electrocoagulation reactor (5) is made of stainless steel plate, and the cathode is made of carbon plate.

4. The apparatus for purifying and reusing water generated from methanol-to-aromatics production according to claim 1, characterized in that: A three-phase cyclone separator (9) is mounted on top of the radial microchannel separator (6); the three-phase cyclone separator (9) is used to form a rotating turbulent flow field to promote the regeneration of the separated medium.

5. The apparatus for purifying and reusing water generated from methanol-to-aromatics production according to claim 1 or 4, characterized in that: The radial microchannel separator (6) is equipped with a multi-stage separation module and a self-cleaning backwashing device; the self-cleaning backwashing device is used to backwash and remove trapped pollutants.

6. The apparatus for purifying and reusing water generated from methanol-to-aromatics production according to claim 5, characterized in that: The multi-stage separation module adopts a three-stage separation module, wherein the first-stage separation module adopts a honeycomb microchannel array, the second-stage separation module adopts a ceramic filter element, and the third-stage separation module adopts an ultrafiltration membrane assembly, which is used to perform gradient interception of flocculated particles of different particle size ranges generated by the electrocoagulation reactor (5).

7. The apparatus for purifying and reusing water generated from methanol-to-aromatics production according to claim 1, characterized in that: The reverse osmosis membrane active separation layer in the reverse osmosis equipment (8) contains a cross-linked network structure, and the reverse osmosis equipment (8) adopts a branched flow membrane stack structure.

8. A method for purifying and reusing water generated from methanol-to-aromatics production, characterized in that, An apparatus for purifying and reusing water generated from methanol-to-aromatics production, as described in any one of claims 1 to 7, wherein the method of reuse includes the following steps: S1: The water generated from methanol to aromatics is transported to the stripping tower (1) for cooling, so that the oxygen-containing compounds in the liquid phase component of the generated water are separated to the concentrated water recovery system. The purified water discharged from the bottom outlet of the stripping tower (1) enters the heat exchanger (3) and the air cooler (4) in sequence for heat exchange and air cooling to regulate the temperature. S2: The purified water after temperature adjustment enters the electrocoagulation reactor (5) for oxidation-reduction treatment, so that dissolved pollutants are converted into flocculated particles and colloidal pollutants are separated by precipitation; S3: The effluent from the electrocoagulation reaction enters the radial microchannel separator (6) to perform deep separation of flocculated particles, resulting in purified water with low suspended solids load; S4: The purified water separated by the radial microchannel separator (6) is pressurized by the second transfer pump (7) and enters the reverse osmosis equipment (8). The residual organic pollutants are removed by the selective permeability of the reverse osmosis membrane to reduce COD. The top outlet of the reverse osmosis equipment (8) outputs recycled purified water and reuses it in the quench tower and / or water washing tower. The bottom outlet outputs concentrated water and enters the concentrated water recovery system. Steps S2-S4 are load reduction processes.

9. The method according to claim 8, characterized in that: The oil content of the purified water treated in step S4 is reduced to 0.2 mg / L, and the turbidity is reduced to 1 NTU.

10. The method according to claim 8 or 9, characterized in that: The pH value of the electrocoagulation reactor (5) is 7-8, and the current intensity is 15-35mA / cm²; the operating pressure of the radial microchannel separator (6) is 0.1-0.3MPa, and the flow rate is 0.8-1.5m / s; the operating pressure of the reverse osmosis equipment (8) is 1.5-4.0MPa.

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