A process and system for recycling purified water in a methanol-to-olefins process

Abstract

The present invention relates to a reuse process and a reuse system for the purified water in the methanol-to-olefins process, belonging to the technical field of water treatment. The specific process is as follows: The purified water in the methanol-to-olefins process enters a KMPR filter. The KMPR filter includes a membrane box and a membrane module disposed in the membrane box. The membrane module in the KMPR filter intercepts the suspended solid particles and oil substances in the purified water of the methanol-to-olefins process. The water produced by the KMPR filter is the final filtrate and can be reused. The concentrated liquid of the KMPR filter is collected for separate treatment. The present invention treats the purified water in the methanol-to-olefins process through the membrane module, and uses the membrane module to remove the suspended solid particles and oil substances, and can intercept most of its suspended solid particles and oil substances, so that the final filtrate can be reused, and the concentrated liquid concentrated by the membrane module is discharged to the sewage treatment plant for treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and in particular relates to a process and system for recycling purified water in a methanol-to-olefins process. Background Art

[0002] MTO (Methanol to Olefins) is short for the methanol-to-olefins process, which refers to the process of preparing light olefins (ethylene and propylene) from methanol through catalytic reactions. The methanol-to-olefins reaction generally uses a fluidized bed reactor. The product gas produced contains various impurities. The product gas (ethylene and propylene) is cleaned and preliminarily cooled through a quench tower and a water wash tower. The water wash water after washing contains a small amount of catalyst and oil substances (such as by-products like mixed alkanes, aromatic hydrocarbons, and coke). Part of the water wash water enters a stripping tower for stripping and purification. The syngas at the top of the stripping tower is sent to an olefin synthesis unit after purification, and the organic substances recovered at the top of the tower (including methanol, dimethyl ether, aldehydes, ketones, etc.) are sent back to the fluidized bed reactor for recycling; the water at the bottom of the tower is the purified water in the methanol-to-olefins process. Currently, the purified water in most methanol-to-olefins processes is discharged to a sewage treatment plant for treatment through a purified water pump. The process flow of the purified water system in the methanol-to-olefins process is shown in Figure 1 as follows.

[0003] Since side reactions occur during the MTO reaction process, a small amount of macromolecular organic substances are generated. Such macromolecular organic substances are prone to condensation at lower temperatures and accumulate in the water wash tower and quench tower to form oil substances. After mixing with catalyst fines, they deposit in the water system, causing blockage of the stripping tower trays and a decrease in the heat exchange efficiency of heat exchange equipment, affecting the long-term operation of the device. To extend the continuous operation cycle of the device and improve the possible adverse effects of oil substances on the entire reaction system, many MTO devices supplement turbine condensate in the stripping tower feed to improve water quality, but at the same time, it brings problems such as a large consumption of steam condensate and an increase in sewage discharge. In the process of methanol-to-olefins, other process steps also require the supplementation of steam condensate, which also causes the consumption of steam condensate.

[0004] Patent CN107382654A discloses a method and device for separating quench water in a methanol-to-olefins process by a boiling fluidized bed. Patent CN205031975U discloses a device for purifying quench water and water wash water using a metal sintered filter element. The above patents all have disadvantages such as low filtration accuracy, inability to remove oil substances (the main cause of fouling), and poor quality of the recycled water. At the same time, they cannot replace the operation mode of supplementing condensate to improve water quality adopted by most current similar MTO devices, and both the operation consumption and the sewage discharge are relatively high. Summary of the Invention

[0005] The purified water in the methanol-to-olefins process mainly contains suspended solids and oil substances. The suspended solids are mainly the catalysts used in the methanol-to-olefins process, and the oil substances have a relatively high viscosity. When coexisting with the fine catalyst powder, they are extremely likely to form fouling and blockage in the system. Therefore, at present, most of the purified water in the methanol-to-olefins process is sent to the sewage treatment plant for treatment. In view of this technical status, the present invention provides a reuse process and a reuse system for the purified water in the methanol-to-olefins process.

[0006] The present invention treats the purified water in the methanol-to-olefins process through a membrane module. By using the membrane module to remove suspended solid particles and oil substances, most of its suspended solid particles and oil substances can be intercepted, so that the final filtrate (i.e., the produced water) can be reused. The produced water can be reused in the stripping tower system or the olefin separation system, or can also be reused in other systems, while the concentrated liquid concentrated by the membrane module is discharged to the sewage treatment plant for treatment.

[0007] The object of the present invention can be achieved through the following technical solutions:

[0008] The present invention first provides a reuse process for the purified water in the methanol-to-olefins process, including the following steps:

[0009] The purified water in the methanol-to-olefins process enters the KMPR filter. The KMPR filter includes a membrane box and a membrane module disposed in the membrane box.

[0010] The membrane module in the KMPR filter intercepts the suspended solid particles and oil substances in the purified water in the methanol-to-olefins process.

[0011] The produced water of the KMPR filter is the final filtrate, and the produced water can be reused. The produced water can be reused in the stripping tower system or the olefin separation system, or can also be reused in other systems. The concentrated liquid of the KMPR filter is collected for separate treatment.

[0012] In an embodiment of the reuse process for the purified water in the methanol-to-olefins process of the present invention, an aeration device is provided at the bottom of the KMPR filter. By distributing the gas into the aeration device at the bottom of the KMPR filter, the aeration device evenly aerates to achieve the flushing and shaking of the membrane module, prevent the solid particles from blocking the membrane pores, prevent the oil substances from adhering to the membrane surface, and at the same time can ensure that the liquid in the membrane box is more evenly mixed.

[0013] In an embodiment of the reuse process for the purified water in the methanol-to-olefins process of the present invention, the gas introduced into the aeration device can be compressed air or other gases, preferably nitrogen or other inert gases.

[0014] In an embodiment of the reuse process for the purified water in the methanol-to-olefins process of the present invention, after the purified water in the methanol-to-olefins process is mixed with the gas, it enters the membrane box of the KMPR filter through a microbubble generator.

[0015] When setting up the microbubble generator, the purified water from the methanol-to-olefins process enters the membrane box. Preferably, after being mixed with gas, it enters the membrane box through the microbubble generator. Under the action of the tiny bubbles generated by the microbubble generator, oil and light suspended solids float to the water surface, reducing the pollution of substances such as oil and suspended solids to the membrane module. Equipment such as pumps, mixers, and ejectors that can generate microbubbles ranging from micrometers to nanometers through gas-liquid mixing can all be classified as a type of microbubble generator.

[0016] The microbubble generator can be selected from ejectors, dissolved air pumps, or other devices where gas and liquid can be mixed.

[0017] In one embodiment of the reuse process of the purified water from the methanol-to-olefins process of the present invention, the concentrated liquid collected for separate treatment can be discharged to a sewage treatment plant for treatment.

[0018] In one embodiment of the reuse process of the purified water from the methanol-to-olefins process of the present invention, the water produced by the KMPR filter also goes to the backwash water tank. The water in the backwash water tank periodically backwashes the membrane module in the KMPR filter. The backwash water does not need to be discharged and can continue to be filtered after backwashing.

[0019] In one embodiment of the reuse process of the purified water from the methanol-to-olefins process of the present invention, the purified water from the methanol-to-olefins process refers to the wastewater at the bottom of the stripping tower in the methanol-to-olefins process. The purified water from the methanol-to-olefins process is a water body containing suspended solids and oil substances. The suspended solids are mainly the catalysts used in the methanol-to-olefins process. The solid content in the purified water from the methanol-to-olefins process is 10 - 30 mg / L, and the oil substance content in the purified water from the methanol-to-olefins process is 0.1 - 10 mg / L.

[0020] In one embodiment of the reuse process of the purified water from the methanol-to-olefins process of the present invention, the water temperature of the purified water from the methanol-to-olefins process is < 50 °C.

[0021] In one embodiment of the reuse process of the purified water from the methanol-to-olefins process of the present invention, the precision of the membrane module is 1 - 100 nm, and the filtration temperature of the membrane module is 5 - 50 °C, more preferably 30 - 45 °C.

[0022] The water production pressure of the KMPR filter is 0.01 - 0.1 MPa, preferably 0.01 - 0.06 MPa.

[0023] The backwash pressure of the KMPR filter is preferably 0.01 - 0.1 MPa, more preferably 0.03 - 0.08 MPa.

[0024] The backwash cycle of the KMPR filter is preferably 100 - 240 min, more preferably 120 - 150 min.

[0025] The backwashing time of the KMPR filter is preferably 50 - 100 s, more preferably 40 - 60 s.

[0026] By adopting the process method of the present invention, the water production recovery rate of using the KMPR filter is ≥90%, the system concentration multiple is ≥10 times. The turbidity is ≤1 NTU, and the removal rate of oil substances is ≥95%.

[0027] The present invention also provides a reuse system for the purified water in the methanol - to - olefins process, including a KMPR filter and a backwashing water tank. The KMPR filter includes a membrane box, a membrane module arranged in the membrane box, a water production pipeline led out from the membrane box, and a concentrated liquid pipeline led out from the membrane box. The water production pipeline leads to the reuse unit and is also shunted and introduced into the backwashing water tank. A backwashing pipeline is connected between the backwashing water tank and the membrane module in the KMPR filter.

[0028] In an embodiment of the reuse system for the purified water in the methanol - to - olefins process of the present invention, one group or multiple groups of membrane modules are arranged in the membrane box, and one or more membrane boxes can also be provided.

[0029] In an embodiment of the reuse system for the purified water in the methanol - to - olefins process of the present invention, an aeration device is arranged at the bottom of the membrane box.

[0030] In an embodiment of the reuse system for the purified water in the methanol - to - olefins process of the present invention, a micro - bubble generator is also provided. The micro - bubble generator is connected to the membrane box through a pipeline for the purified water in the methanol - to - olefins process to enter. After the purified water in the methanol - to - olefins process is mixed with gas, it enters the membrane box of the KMPR filter through the micro - bubble generator.

[0031] In an embodiment of the reuse system for the purified water in the methanol - to - olefins process of the present invention, a water production pump is arranged on the water production pipeline. Clean water production is sucked out through the water production pump. The water production can be returned to the stripping tower or the olefin separation process, or can also be reused in other production processes, and at the same time, a pipeline is provided to go to the backwashing water tank.

[0032] In an embodiment of the reuse system for the purified water in the methanol - to - olefins process of the present invention, a backwashing pump is arranged on the backwashing pipeline. The KMPR filter controls the backwashing pump to conduct backwashing regularly through a program. The backwashing water does not need to be discharged and can continue to operate after backwashing. After the backwashing pressure reaches a certain value, the operation is stopped for chemical cleaning, and it can continue to operate after the chemical cleaning is completed.

[0033] In an embodiment of the reuse system for the purified water in the methanol - to - olefins process of the present invention, a concentrated liquid pump is arranged on the concentrated liquid pipeline. The concentrated liquid in the membrane box is transported through the concentrated liquid pump or directly discharged by gravity to the sewage system.

[0034] In an embodiment of the reuse system of the purified water in the methanol-to-olefins process of the present invention, the KMPR filter is an atmospheric pressure device, and the bottom is a flat bottom or a conical bottom.

[0035] In an embodiment of the reuse system of the purified water in the methanol-to-olefins process of the present invention, the microbubble generator can be an ejector, a dissolved air pump, or other devices in which gas and liquid can be mixed.

[0036] In an embodiment of the reuse system of the purified water in the methanol-to-olefins process of the present invention, the membrane module is selected from organic or inorganic membrane materials with good hydrophilicity, oil resistance, and organic solvent resistance, and more preferably materials such as PTFE, PP, ceramics, stainless steel, graphene, etc. The form of the membrane module is selected from forms such as hollow fiber, flat plate, or tubular.

[0037] In the present invention, one KMPR filter device simultaneously has two major functions of turbidity removal and oil removal, and has a high interception rate for oil substances and suspended solids.

[0038] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0039] (1) By adopting the process or system of the present invention, the water recovery rate is high (>90%), and the load of the subsequent sewage treatment plant is greatly reduced;

[0040] (2) The KMPR filter simultaneously has two major functions of turbidity removal and oil removal, has a high removal rate for suspended solids and oil, and the concentrations of oil and suspended solids in the produced water are lower than the detection limit;

[0041] (3) The process flow is simple and reasonable, and the investment and operation costs are low;

[0042] (4) The operation is simple, the stability is good, the automation degree is high, and the operation cycle is long;

[0043] (5) The filtration accuracy is high, and the quality of the recycled water is high;

[0044] (6) It can replace the use of steam condensate in the process, and greatly reduces the operation cost of the MTO device. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is the process flow chart of the purified water system in the prior art;

[0046] Figure 2 is the reuse process flow of the purified water in the methanol-to-olefins process Figure 1 ;

[0047] Figure 3 is the reuse process flow of the purified water in the methanol-to-olefins process Figure 2 . DETAILED DESCRIPTION OF THE INVENTION

[0048] refer to Figure 2 The present invention provides a reuse system for purified water in a methanol to olefins process, comprising a KMPR filter 2 and a backwash water tank 8. The KMPR filter 2 comprises a membrane box 4, a membrane assembly 3 arranged in the membrane box 4, a production water pipeline led out of the membrane box 4, and a concentrated liquid pipeline led out of the membrane box 4. The production water pipeline is led to a reuse unit and is also diverted to the backwash water tank 8. A backwash pipeline is connected between the backwash water tank 8 and the membrane assembly 3 in the KMPR filter 2.

[0049] In one embodiment of the methanol to olefins process purified water reuse system of the present invention, the membrane modules 3 in the membrane box 4 are arranged in one or more groups, and the membrane box 4 can also be arranged in one or more groups.

[0050] In one embodiment of the system for reusing purified water in a methanol-to-olefins process of the present invention, an aeration device 9 is provided at the bottom of the membrane box 4 .

[0051] In one embodiment of the methanol to olefins process purified water recycling system of the present invention, the produced water pipeline is provided with a produced water pump 5. The produced water pump 5 pumps clean produced water, which can be returned to the stripping tower or the olefin separation process, and is also provided to go to the backwash water tank.

[0052] In one embodiment of the methanol to olefins process purified water reuse system of the present invention, a backwash pump 6 is provided on the backwash pipeline, and the KMPR filter 2 performs backwashing at regular intervals by program-controlled backwash pump 6, and the backwash water does not need to be discharged and can continue to be filtered after backwashing.

[0053] In one embodiment of the methanol to olefins process purified water reuse system of the present invention, the concentrate pipeline is provided with a concentrate pump 7. The concentrate in the membrane box is transported by the concentrate pump or directly discharged to the sewage system by gravity.

[0054] In one embodiment of the methanol to olefins process purified water reuse system of the present invention, the membrane assembly 3 is selected from organic or inorganic membrane materials with good hydrophilicity, oil resistance, and organic solvent resistance, and more preferably PTFE, PP, ceramic, stainless steel, graphene, etc. The form of the membrane assembly 3 is selected from hollow fiber, flat plate, or tubular forms.

[0055] refer to Figure 3 ,and Figure 2 The difference is that the reuse system of the methanol to olefins process purified water is also provided with a microbubble generator 1, and the microbubble generator 1 is connected to the membrane box 4 through the methanol to olefins process purified water inlet pipeline. After the methanol to olefins process purified water is mixed with the gas, it enters the membrane box 4 of the KMPR filter 2 through the microbubble generator 1.

[0056] The microbubble generator 1 can be a jet injector, a dissolved air pump, or other devices where gas and liquid can be mixed.

[0057] A KMPR filter 2 device has two major functions of turbidity removal and oil removal, and has a relatively high interception rate for oil substances and suspended solids.

[0058] Reference Figure 2 , the present invention also provides a reuse process for the purified water in the methanol-to-olefins process, including the following steps:

[0059] The purified water in the methanol-to-olefins process enters the KMPR filter 2, and the KMPR filter 2 includes a membrane box 4 and a membrane module 3 disposed in the membrane box 4.

[0060] The membrane module 3 in the KMPR filter 2 intercepts the suspended solid particles and oil substances in the purified water of the methanol-to-olefins process.

[0061] The produced water of the KMPR filter 2 is the final filtrate, and the produced water can be reused.

[0062] The concentrated liquid of the KMPR filter 2 is collected for separate treatment.

[0063] In an embodiment of the reuse process for the purified water in the methanol-to-olefins process of the present invention, an aeration device 9 is provided at the bottom of the KMPR filter 2. By distributing gas to the aeration device at the bottom of the KMPR filter, the aeration device 9 evenly aerates to achieve scouring and jittering of the membrane module 3, prevent solid particles from blocking the membrane pores, prevent oil substances from adhering to the membrane surface, and at the same time ensure that the liquid in the membrane box is more evenly mixed.

[0064] In an embodiment of the reuse process for the purified water in the methanol-to-olefins process of the present invention, the gas introduced into the aeration device 9 can be compressed air or other gases, preferably nitrogen or other inert gases.

[0065] In an embodiment of the reuse process for the purified water in the methanol-to-olefins process of the present invention, the separate treatment of the collected concentrated liquid can be discharging it to a sewage treatment plant for treatment.

[0066] In an embodiment of the reuse process for the purified water in the methanol-to-olefins process of the present invention, the produced water of the KMPR filter 2 also goes to the backwash water tank 8. The water in the backwash water tank 8 periodically backwashes the membrane module 3 in the KMPR filter 2. The backwash water does not need to be discharged and can continue to operate after backwashing. After the backwash pressure reaches a certain value, the operation is stopped for chemical cleaning, and it can continue to operate after the chemical cleaning is completed.

[0067] In an embodiment of the reuse process of the purified water in the methanol - to - olefins process of the present invention, the purified water in the methanol - to - olefins process refers to the wastewater at the bottom of the stripping column in the methanol - to - olefins process. The purified water in the methanol - to - olefins process is a water body containing suspended solids and oil substances. The solid content in the purified water in the methanol - to - olefins process is 10 - 30 mg / L, and the oil substance content in the purified water in the methanol - to - olefins process is 0.1 - 10 mg / L.

[0068] In an embodiment of the reuse process of the purified water in the methanol - to - olefins process of the present invention, the water temperature of the purified water in the methanol - to - olefins process is < 50 °C.

[0069] In an embodiment of the reuse process of the purified water in the methanol - to - olefins process of the present invention, the precision of the membrane module 3 is 1 - 100 nm, and the filtration temperature of the membrane module 3 is 5 - 50 °C, more preferably 30 - 45 °C.

[0070] The water production pressure of the KMPR filter 2 is 0.01 - 0.1 MPa, preferably 0.01 - 0.06 MPa.

[0071] The backwashing pressure of the KMPR filter 2 is preferably 0.01 - 0.1 MPa, more preferably 0.03 - 0.08 MPa.

[0072] The backwashing cycle of the KMPR filter 2 is preferably 100 - 240 min, more preferably 120 - 150 min.

[0073] The backwashing time of the KMPR filter 2 is preferably 50 - 100 s, more preferably 40 - 60 s.

[0074] Reference Figure 3 , in an embodiment of the reuse process of the purified water in the methanol - to - olefins process of the present invention, after the purified water in the methanol - to - olefins process is mixed with gas, it enters the membrane box 4 of the KMPR filter 2 through the micro - bubble generator 1. When the micro - bubble generator 1 is set, the purified water in the methanol - to - olefins process enters the membrane box 4, preferably after being mixed with gas and then entering the membrane box 4 through the micro - bubble generator 1. Oil and light suspended solids float to the water surface under the action of the tiny bubbles generated by the micro - bubble generator 1, reducing the pollution of substances such as oil and suspended solids to the membrane module 3.

[0075] Adopting the process method of the present invention, the water production recovery rate of the KMPR filter 2 is ≥ 90%, and the system concentration multiple is ≥ 10 times. The turbidity of the final filtrate is ≤ 1 NTU, and the removal rate of oil substances is ≥ 95%.

[0076] The following specifically describes the present invention with reference to specific embodiments.

[0077] Example 1

[0078] The process water of the methanol-to-olefins process is treated using the process flow shown as follows. The temperature of the process water of the methanol-to-olefins process is 40 °C, the solid content is 18 mg / L, and the oil content is 3 mg / L. Driven by a microbubble generator, it is fully mixed with nitrogen to form tiny bubbles, which enter the KMPR filter. Through the suction of the product water pump, clean product water is produced, and part of the product water is transported to the backwash water tank. The KMPR filter is an atmospheric pressure vessel. After mixing with the feed, the tiny bubbles carry oil droplets and gradually float to the surface layer of the membrane filter, gradually forming an oil film. The surface oil film discharges oil substances out of the system through regular scraper slag discharge or overflow to the sewage treatment plant. The concentrated liquid contains a large amount of concentrated suspended solids and oil substances, and the bottom aeration device is used to keep the mixture in the filter evenly suspended. Figure 3 It is concentrated 20 times. The concentrated liquid and oil slag enter the sewage treatment plant, and the filtrate is directly returned to the stripping tower system. The product water pump of the membrane filter system runs for 9 minutes and stops for 1 minute, with continuous feeding, continuous aeration, and continuous discharge of the concentrated liquid. Backwashing is carried out for 60 seconds every 2 hours, and chemical cleaning is carried out once a month.

[0079] In this embodiment, the quality of the filtrate and the water recovery rate are shown in Table 1:

[0080] In this embodiment, the quality of the filtrate and the water recovery rate are shown in Table 1:

[0081] Table 1

[0082] Turbidity of filtrate NTU 0.5 Oil content of filtrate mg / L Not detected Recovery rate ％ 95

[0083] Example 2

[0084] The process water of the methanol-to-olefins process is treated using the process flow shown as follows. The temperature of the process water of the methanol-to-olefins process is 37 °C, the solid content is 10 mg / L, and the oil content is 1 mg / L. The process water enters the KMPR filter, and water is produced through the suction of the product water pump. Part of the product water is transported to the backwash water tank. After the backwash water tank reaches the high liquid level, the product water is discharged to the olefin separation system for reuse. The concentrated liquid contains a large amount of concentrated suspended solids and oil substances, and the bottom aeration device is used to keep the concentrated liquid in the filter evenly mixed. It is concentrated 10 times, and the concentrated liquid and oil slag enter the sewage treatment plant. The product water pump of the membrane filter system runs for 60 minutes and stops for 1 minute, with continuous feeding, continuous aeration, and continuous discharge of the concentrated liquid. Backwashing is carried out for 100 seconds every 150 minutes, and chemical cleaning is carried out regularly. Figure 2 The quality of the filtrate and the water recovery rate are shown in Table 2:

[0085] The quality of the filtrate and the water recovery rate are shown in Table 2:

[0086] Table 2

[0087] Turbidity of filtrate NTU 0.3 Oil content of filtrate mg / L Not detected Recovery rate ％ 90

[0088] Example 3

[0089] The process water of the methanol-to-olefins process is treated using the process flow shown as follows. Figure 2The process flow shown is used to treat the purified water from the methanol-to-olefins process. The water temperature of the purified water from the methanol-to-olefins process is 40°C, the solid content is 30 mg / L, and the oil content is 5 mg / L. The purified water and compressed air enter the KMPR filter through a microbubble generator, and clean water is produced under the suction of the water production pump. Part of the produced water is transported to the backwash water tank, and when the water production tank reaches the high liquid level, the produced water is reused. The concentrated liquid contains a large amount of concentrated suspended solids and oil substances, and the concentrated liquid in the filter is kept in a suspended state by mixing evenly through the bottom aeration device. It is concentrated 10 times, and the concentrated liquid and oil slag enter the sewage treatment plant. The water production pump of the membrane filter system runs for 60 minutes and stops for 1 minute, with continuous feeding, continuous aeration, and continuous discharge of the concentrated liquid. Backwashing is carried out for 50 seconds every 100 minutes, and chemical cleaning is carried out once a month.

[0090] The quality of the filtrate and the water recovery rate are shown in Table 3 as follows:

[0091] Table 3

[0092] Turbidity of filtrate NTU 0.8 Oil content of filtrate mg / L Not detected Recovery rate ％ 90

[0093] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention as disclosed should be within the protection scope of the present invention.

Claims

1. A process for recycling the purified water in a methanol-to-olefins process, characterized in that, The method includes the following steps: The purified water from the methanol-to-olefins process enters the KMPR filter (2). The KMPR filter (2) includes a membrane box (4) and a membrane module (3) disposed in the membrane box (4). The membrane module (3) in the KMPR filter (2) intercepts suspended solid particles and oil substances in the purified water from the methanol-to-olefins process. The water produced by the KMPR filter (2) is the final filtrate and is recycled to the production process. The concentrated liquid of the KMPR filter (2) is collected for separate treatment. After being mixed with gas, the purified water from the methanol-to-olefins process enters the membrane box (4) of the KMPR filter (2) through a microbubble generator (1). The purified water from the methanol-to-olefins process is a water body containing suspended solids and oil substances. The suspended solids are the catalysts used in the methanol-to-olefins process. The solid content in the purified water from the methanol-to-olefins process is 10 - 30 mg / L, and the oil substance content in the purified water from the methanol-to-olefins process is 0.1 - 10 mg / L. The precision of the membrane module (3) is 1 - 100 nm, and the filtration temperature of the membrane module (3) is 5 - 50 °C. The water production pressure of the KMPR filter (2) is selected to be 0.01 - 0.1 MPa.

2. The reuse process of the purified water in the methanol-to-olefins process according to claim 1, wherein, An aeration device (9) is arranged at the bottom of the KMPR filter (2). The uniform aeration of the aeration device (9) realizes the flushing and shaking of the membrane module (3) and the mixing of the liquid in the membrane box.

3. The reuse process of the purified water in the methanol-to-olefins process according to claim 1, characterized in that, The water produced by the KMPR filter (2) also goes to the backwash water tank (8). The water in the backwash water tank (8) periodically backwashes the membrane module (3) in the KMPR filter (2).

4. The reuse process of the purified water in the methanol-to-olefins process according to claim 1, characterized in that, The backwash pressure of the KMPR filter (2) is selected to be 0.01 - 0.1 MPa. The backwash cycle of the KMPR filter (2) is selected to be 100 - 240 min. The backwash time of the KMPR filter (2) is selected to be 50 - 100 s.

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