Method for recovering methanol and acetone in oxide waste liquid and separation system

Abstract

The invention relates to a method for recovering methanol and acetone in an oxide waste liquid, a separation system and a methanol-to-olefin waste liquid treatment method, and the method comprises the following steps: sending the oxide-containing waste liquid to a light component removal tower, obtaining an acetaldehyde material at the tower top, sending a tower bottom discharge material into a methanol-acetone azeotrope tower, obtaining a methanol-acetone azeotrope at the tower top, sending a tower bottom discharge material into an oxide separation tower, an oxide-water mixture is obtained at the tower top, and water is discharged from the tower bottom; feeding the methanol-acetone azeotrope into an extractive distillation tower, and performing extraction separation by taking water as an extracting agent to obtain an acetone product at the tower top and a methanol-water mixture at the tower bottom; performing pervaporation dehydration refining on the methanol-water mixture to obtain a methanol product; the oxide-water mixture is subjected to pervaporation, dehydration and concentration, and the oxide mixture fuel is obtained. The content of oxides in the wastewater treated by the method provided by the invention can be reduced to below 1wt%, various organic matter products can be obtained while the oxide waste liquid is effectively treated, and the economic benefit is good.

Description

Technical Field

[0001] The invention relates to a method for recovering and treating high-concentration oxide waste liquid from methanol to olefins, and belongs to the fields of environmental protection and chemical industry. Background Art

[0002] For methanol to olefins technology, methanol, in addition to producing ethylene and propylene, also produces a small amount of alcohol, aldehyde, ketone and other oxides in the reaction process. After these oxides enter the water scrubber and stripping tower along with the process gas, part of them enter the water to form oxide waste liquid, which is usually used as fuel for combustion treatment. However, since the water content of this part of oxide waste liquid is very high (about 60-80w%) and the output is large, it is difficult to burn and difficult to handle. The oxygen-containing organic matter in the oxide waste liquid, materials such as alcohol, aldehyde, ketone, can be used as industrial solvents and organic raw materials in industries such as chemical and pharmaceutical industries. If they are separated and recovered, the cost of coal liquefaction to olefins can be further reduced and its biodegradability can be improved.

[0003] The oxides contained in the oxide waste liquid of methanol to olefins are mainly acetaldehyde (boiling point 20.99°C), methanol (boiling point 64.53°C), acetone (boiling point 56.14°C), and also contain small amounts of ethanol, n-propanol, isopropanol, butanol, butanone, pentanone, hexanone, pentenone, etc. Except for acetaldehyde, these oxides can form a variety of azeotropes with each other, which are difficult to separate.

[0004] CN102040303A discloses a method for recovering organic matter in wastewater from a methanol-to-olefins process. The method uses a pervaporation membrane or a steam permeation membrane that preferentially permeates organic matter to separate organic matter from water in the wastewater, and then the organic matter containing methanol is subjected to steam stripping treatment. The stripping product is then dehydrated through a pervaporation membrane or a steam permeation membrane that preferentially permeates water to obtain methanol and derivative products. The recovery method ultimately obtains a mixture of multiple aldehydes, ketones, and alcohols, and does not perform deep separation of the mixture to obtain a high-purity single-component organic product.

[0005] CN103044217A discloses a method for treating non-acidic oxygen-containing organic matter. The invention first uses distillation to extract all the light components of non-acidic organic matter such as acetaldehyde, ethanol, propionaldehyde, acetone, and n-propanol in wastewater, and then cuts, separates, and refines them in sequence. The process is complicated. In addition, to extract all the organic matter together, the tower bottom needs to be heated to a higher temperature first. This temperature is higher than the tower bottom temperature of most subsequent product refining towers, and it needs to be repeatedly heated and cooled, which consumes a lot of energy.

[0006] CN111499495A discloses a method for recovering various alcohols from troxtrostatic synthesis wastewater. In the invention, the recovered alcohols are dehydrated and refined by distillation to obtain high-purity products. The heating temperature is high and the energy consumption is large. In addition, the invention does not involve the recovery of ketone substances.

[0007] CN103467257A and CN103483148A disclose methods for recovering aldehydes, ketones and alcohols in trotropsch synthesis water using multiple distillation units. The invention ultimately obtains a mixed alcohol product that can only be burned as fuel without deep separation of the mixture. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a recovery and treatment method and a separation system for high-concentration oxide waste liquid.

[0009] In a first aspect, the present invention provides a method for recovering methanol and acetone in oxide waste liquid, wherein the oxide waste liquid is sent to a light-removing tower, acetaldehyde material is obtained at the top of the tower, the bottom of the tower is discharged into a methanol-acetone azeotrope tower, methanol-acetone azeotrope is obtained at the top of the tower, the bottom of the tower is discharged into an oxide separation tower, an oxide-water mixture is obtained at the top of the tower, and the bottom of the tower is water; the methanol-acetone azeotrope is sent to an extractive distillation tower, water is used as an extractant for extraction and separation, an acetone product is obtained at the top of the tower, and a methanol-water mixture is obtained at the bottom of the tower; the methanol-water mixture is subjected to pervaporation dehydration and refining to obtain a methanol product; the oxide-water mixture is subjected to pervaporation dehydration and concentration to obtain an oxide mixture fuel.

[0010] In a second aspect, the present invention provides a separation system for recovering methanol and acetone in oxide waste liquid, which is used in the above-mentioned method for recovering methanol and acetone in oxide waste liquid, comprising a light removal tower, a methanol-acetone azeotrope tower, an oxide separation tower, an extractive distillation tower, a first membrane separator and a second membrane separator connected in sequence, wherein the light removal tower is used to separate low-boiling organic oxygenates, and the bottom discharge of the tower is connected to the raw material inlet of the methanol-acetone azeotrope tower;

[0011] The methanol-acetone azeotrope tower is used to separate the methanol-acetone azeotrope, the bottom discharge of the tower is connected to the raw material inlet of the oxide separation tower, and the top discharge of the methanol-acetone azeotrope tower is connected to the raw material inlet of the extraction distillation tower;

[0012] The oxide separation tower is used to separate the remaining oxide mixture in the wastewater, the top discharge of the tower is connected to the first membrane separator, and the bottom discharge of the tower is discharged externally;

[0013] The extractive distillation tower is used to separate methanol and acetone, the material discharged from the top of the tower is discharged externally, and the material discharged from the bottom of the tower is connected to the second membrane separator.

[0014] In a third aspect, the present invention provides a method for treating waste liquid from methanol to ethylene, wherein the reaction product of the methanol to olefin process enters a water washing tower, and the obtained waste water containing organic oxides is sent to a stripping tower, and the gas phase after stripping is cooled by heat exchange at the top of the tower to obtain an oxide-containing waste liquid; the above-mentioned method for recovering methanol and acetone in the oxide waste liquid is used to treat the oxide-containing waste liquid to obtain an acetone product and a methanol product.

[0015] Compared with the prior art, the method and separation system for recovering methanol and acetone from oxide waste liquid provided by the present invention have the following beneficial effects:

[0016] Compared with the prior art, the method provided by the present invention extracts methanol and acetone from the oxide waste liquid in the form of an azeotrope, and can treat the oxide waste liquid at a lower temperature to reduce the content of oxides therein. The methanol-acetone azeotrope is further separated to obtain high-purity methanol and acetone products, creating new revenue for the enterprise.

[0017] The method provided by the present invention recovers the oxides in the waste liquid of methanol to olefin oxide in order from low to high boiling points by distillation according to the difference in boiling points of the oxides, without repeated heating, thereby reducing energy consumption. The recovered oxides are refined or dehydrated and concentrated by pervaporation membrane separation, and the steps are simple. The oxide content in the final waste liquid can be reduced to below 1wt%, and it can meet the discharge standards. While effectively treating the oxide waste liquid, high-purity acetaldehyde, methanol, and acetone products are also obtained, and the recovery rate of methanol and acetone is improved. The concentrated oxide mixture containing a small amount of water can be used as fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a schematic flow diagram of the method for recovering methanol and acetone from oxide waste liquid.

[0019] in:

[0020] 1- Light removal tower 2- Methanol-acetone azeotrope tower 3- Extraction distillation tower

[0021] 4-Oxide separation tower 5-First membrane separator 6-Second membrane separator

[0022] 7-Oxygenated waste liquid 8-Acetaldehyde product 9-Light removal tower kettle discharge

[0023] 10-methanol-acetone azeotrope 11-azeotrope tower bottom discharge 12-acetone product

[0024] 13- Extraction distillation tower bottom discharge 14- Oxide-water mixture 16- Methanol product

[0025] 17- Concentrated oxide-water mixture 19- Extractant water

[0026] 15, 18, 20, 21-Pipeline DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are described in detail below:

[0028] In this application, the pressures referred to are apparent pressures.

[0029] In this application, the descriptions such as "top", "middle", and "bottom" are all based on the relative position of the container. The "bottom" refers to the position of 0-10% from the bottom to the top of the container, the "middle" refers to the position of 40-60% from the bottom to the top of the container, and the "top" refers to the position of 90-100% from the bottom to the top of the container.

[0030] In a first aspect, the present invention provides a method for recovering methanol and acetone in oxide waste liquid, wherein the oxide waste liquid is sent to a light-removing tower, acetaldehyde material is obtained at the top of the tower, the bottom of the tower is discharged into a methanol-acetone azeotrope tower, methanol-acetone azeotrope is obtained at the top of the tower, the bottom of the tower is discharged into an oxide separation tower, an oxide-water mixture is obtained at the top of the tower, and the bottom of the tower is water; the methanol-acetone azeotrope is sent to an extractive distillation tower, water is used as an extractant for extraction and separation, an acetone product is obtained at the top of the tower, and a methanol-water mixture is obtained at the bottom of the tower; the methanol-water mixture is subjected to pervaporation dehydration and refining to obtain a methanol product; the oxide-water mixture is subjected to pervaporation dehydration and concentration to obtain an oxide mixture fuel.

[0031] In the method provided by the present invention, in the oxide-containing waste liquid, the content of organic oxides is 20wt%-40wt%, the content of water is 60wt%-80wt%, and the organic oxides include at least methanol, acetone and acetaldehyde.

[0032] Optionally, the methanol content in the oxide-containing waste liquid is 7wt%-12wt%, the acetone content is 16wt%-20wt%, the acetaldehyde content is 2wt%-6wt%, and the content of other C1-C6 oxide mixtures is 1wt%-4wt%.

[0033] Optionally, the top discharge of the oxide separation tower is an oxide-water mixture, containing 60wt%-70wt% of the oxide mixture and 30wt%-40wt% of water, and the oxide mixture includes methanol, ethanol, n-propanol, isopropanol, butanol, butanone, pentanone, hexanone and pentenone; the water content in the bottom discharge is >99wt%, and the oxide content is <1wt%.

[0034] In the method provided by the present invention, the operating conditions of the lightness removal tower are: normal pressure operation, reflux ratio of 1-2, tower top temperature of 20-28°C, tower bottom temperature of 50-73°C;

[0035] The operating conditions of the methanol-acetone azeotrope tower are: pressure of 0-0.2 MPa, reflux ratio of 2-6, tower top temperature of 50-90°C, and tower bottom temperature of 70-120°C;

[0036] The operating conditions of the extractive distillation tower are: atmospheric pressure operation, the feed ratio of the extractant to the methanol-acetone azeotrope is 2-5, the reflux ratio is 2-4, the tower top temperature is 55-65°C, and the tower bottom temperature is 60-75°C;

[0037] The operating conditions of the oxide separation tower are: normal pressure operation, reflux ratio of 1-3, tower top temperature of 70-100°C, and tower bottom temperature of 90-130°C.

[0038] Optionally, part of the acetone product obtained from the extractive distillation tower is recycled back to the methanol-acetone azeotrope tower for further treatment; preferably, 25%-50% of the acetone product is returned to the methanol-acetone azeotrope tower.

[0039] In the light removal tower, acetaldehyde product (boiling point at normal pressure is 20.99°C) is obtained at the top of the tower, wherein the acetaldehyde purity is >98%, and it may also contain other organic oxygen-containing compounds with boiling points less than 28°C at normal pressure, such as dimethyl ether. The bottom discharge is sent to a methanol-acetone azeotrope tower for distillation separation, and a methanol-acetone azeotrope is obtained at the top of the tower. The methanol-acetone azeotrope has a boiling point of 55.8°C at normal pressure. The bottom discharge is sent to an oxide separation tower for further separation, and a mixture of oxides and water is obtained at the top of the oxide separation tower. Preferably, the top discharge of the oxide separation tower contains 60wt%-70wt% of an oxide mixture and 30wt%-40wt% of water; the oxide mixture includes methanol, ethanol, n-propanol, isopropanol, butanol, butanone, pentanone, hexanone and pentenone; the bottom discharge is treated wastewater, wherein the water content is >99wt%.

[0040] The methanol-acetone azeotrope is transported to an extractive distillation tower, where they are separated using water as an extractant. An acetone product with a purity of >96% is obtained at the top of the tower, and a methanol-water mixture is obtained at the bottom of the tower.

[0041] Preferably, the acetone product portion at the top of the tower is returned to the methanol-acetone azeotrope tower to recover as much methanol as possible in the oxide liquid.

[0042] In the method provided by the present invention, the methanol-water mixture is subjected to pervaporation dehydration and purification, the pervaporation membrane is an inorganic molecular sieve membrane, and a methanol product is obtained; the operating temperature of the dehydration and concentration is 60-80°C, the permeation side of the inorganic molecular sieve membrane is evacuated to -0.08 to -0.1 MPa, and the water content of the methanol after dehydration is less than 0.5wt%.

[0043] The oxide-water mixture is subjected to pervaporation dehydration and concentration, the pervaporation membrane is an inorganic molecular sieve membrane, and the dehydrated and concentrated oxide-water mixture can be used as fuel; the operating temperature of the dehydration and concentration is 60-80°C, the permeation side of the inorganic molecular sieve membrane is evacuated to -0.08 to -0.1 MPa, and the water content of the dehydrated oxide-water mixture is less than 5wt%;

[0044] In a second aspect, the present invention provides a separation system for recovering methanol and acetone in oxide waste liquid, which is used in the above-mentioned method for recovering methanol and acetone in high-concentration oxide waste liquid, comprising a light removal tower, a methanol-acetone azeotrope tower, an oxide separation tower, an extractive distillation tower, a first membrane separator and a second membrane separator connected in sequence, wherein the light removal tower is used to separate low-boiling organic oxygen-containing substances, and the bottom discharge of the tower is connected to the raw material inlet of the methanol-acetone azeotrope tower;

[0045] The methanol-acetone azeotrope tower is used to separate the methanol-acetone azeotrope, the bottom discharge of the tower is connected to the raw material inlet of the oxide separation tower, and the top discharge of the methanol-acetone azeotrope tower is connected to the raw material inlet of the extraction distillation tower;

[0046] The oxide separation tower is used to separate the remaining oxide mixture in the wastewater, the top discharge of the tower is connected to the first membrane separator, and the bottom discharge of the tower is discharged externally;

[0047] The extractive distillation tower is used to separate methanol and acetone, the material discharged from the top of the tower is discharged externally, and the material discharged from the bottom of the tower is connected to the second membrane separator.

[0048] Optionally, the top discharge of the extractive distillation tower is connected to the raw material inlet of the methanol-acetone azeotrope tower.

[0049] In a third aspect, the present invention provides a method for treating waste liquid from methanol to ethylene, wherein the reaction product of the methanol to olefin process enters a water washing tower, and the obtained waste water containing organic oxides is sent to a stripping tower, and the gas phase after stripping is cooled by heat exchange at the top of the tower to obtain an oxide-containing waste liquid; the above-mentioned method for recovering methanol and acetone in the oxide waste liquid is used to treat the oxide-containing waste liquid to obtain an acetone product and a methanol product.

[0050] The method for recovering methanol and acetone in oxide waste liquid provided by the present invention is to respectively obtain high-purity acetaldehyde and acetone products, as well as methanol-water mixture and oxide-water mixture by setting an acetaldehyde tower, a methanol-acetone azeotrope tower, a methanol-acetone azeotrope extraction distillation tower and an oxide separation tower, and preferably the obtained acetone product is partially recycled back to the methanol-acetone azeotrope tower to increase the amount of methanol recovered from the oxide waste liquid. The methanol-water mixture is dehydrated and refined by pervaporation to obtain a high-purity methanol product, and the oxide-water mixture can be burned as fuel after dehydration and concentration. The oxide content in the final oxide waste liquid can be reduced from 30-40wt% to less than 1wt%, and the discharge is up to standard. While effectively treating the oxide waste liquid, a variety of high-purity organic products are also obtained, creating new income.

[0051] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0052] Attached Figure 1 The schematic diagram of the process of the present invention for recovering methanol and acetone from oxide waste liquid is shown in the attached figure. Figure 1 As shown, the oxygenate-containing waste liquid 7 is transported to the light-removing tower 1, which is fed from the middle part of the light-removing tower 1, and the acetaldehyde product 8 is obtained by discharging from the top of the tower. The discharge material 9 of the bottom of the light-removing tower is the remaining organic oxygenates and water, which is fed from the middle part of the methanol-acetone azeotropic tower and transported to the methanol-acetone azeotropic tower 2, and the methanol-acetone azeotrope 10 is obtained at the top of the methanol-acetone azeotropic tower. The remaining organic oxygenates are used as the bottom discharge material 11 of the azeotropic tower, which is sent from the middle part to the oxide separation tower 4 for fractional distillation and dehydration, and the oxide-water mixture 14 is obtained at the top of the oxide separation tower, and the water produced from the bottom of the tower is discharged through the pipeline 15. The methanol-acetone azeotrope 10 is sent to the extractive distillation tower 3, and the extractant water 19 enters the extractive distillation tower 3 from the middle. After extractive distillation, the acetone product 12 is obtained at the top of the extractive distillation tower 3. A part of the acetone product is recycled back to the methanol-acetone azeotrope tower 2 through the pipeline 18, and the feed is fed from the middle of the methanol-acetone azeotrope tower; the extractive distillation tower 3 is discharged from the bottom of the tower as a methanol-water mixture. The methanol-water mixture enters the first membrane separator 5 through the pipeline 13, and is dehydrated and concentrated by the pervaporation membrane assembly to obtain the methanol product 16, and the removed water is discharged through the pipeline 20. The oxide-water mixture 14 obtained at the top of the oxide separation tower 4 enters the second membrane separator 6 through the pipeline, and is dehydrated and concentrated by the pervaporation membrane assembly to obtain the concentrated oxide-water mixture 17, and the removed water is discharged through the pipeline 20.

[0053] The present invention is further described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0054] The oxide-containing waste liquid used in the embodiment comes from the condensed liquid at the bottom of the high fraction tank at the top of the stripping tower after the methanol to olefins reactor. The composition of the oxide waste liquid is shown in Table 1.

[0055] The pervaporation membrane components used in the examples are molecular sieve membranes, all purchased from Nanjing Jiutian Hi-Tech Co., Ltd.

[0056] Example 1

[0057] The process flow is as follows Figure 1 As shown, the specific operation process is:

[0058] (1) The oxygenated waste liquid is transported to a light-removal tower, and the material is fed from the 8th theoretical plate (counted from bottom to top, the same below). The acetaldehyde product is obtained from the top of the tower, and the remaining organic oxygenated substances and water are discharged from the bottom of the tower.

[0059] (2) In step (1), the bottom stream is fed from the 18th theoretical plate to a methanol-acetone azeotrope, and a methanol-acetone azeotrope is obtained at the top of the tower, and the remaining organic oxygenates are discharged from the bottom of the tower.

[0060] (3) The top discharge of step (2) is sent to extractive distillation tower 3, and is fed from the third theoretical plate. Extractant water is fed from the fifth theoretical plate. The mass ratio of extractant water to feed stream (methanol-acetone azeotrope) is 3. An acetone product is obtained from the top of the extractive distillation tower. 1 / 2 of the acetone product is transported back to the methanol-acetone azeotrope tower and is fed from the 22nd theoretical plate of the methanol-acetone azeotrope tower. The bottom discharge of the extractive distillation tower is a methanol-water mixture.

[0061] (4) In step (2), the bottom stream of the tower is fed from the 13th theoretical plate to the oxide separation tower, and the oxide-water mixture is obtained at the top of the oxide separation tower, and the bottom discharge is water.

[0062] (5) The methanol-water mixture obtained in step (3) enters the first membrane separator, and is dehydrated and concentrated by a pervaporation membrane module to obtain a methanol product and water, wherein the water content of the obtained methanol is 0.48 wt%. The operating temperature of the first membrane separator is 60° C., the membrane permeation side is evacuated to -0.08 MPa, and the membrane permeation flux is 1.5 kg / m 2 / h.

[0063] (6) The oxide-water mixture obtained in step (4) enters the second membrane separator, and is dehydrated and concentrated by a pervaporation membrane assembly to obtain a concentrated oxide-water mixture and water, wherein the water content of the concentrated oxide-water mixture is 4.2w%; the operating temperature of the second membrane separator is 60°C, the membrane permeation side is evacuated to -0.08MPa, and the membrane permeation flux is 2.1kg / m 2 / h.

[0064] The operating conditions of each distillation tower are shown in Table 2, the composition of the tower top and tower bottom logistics are shown in Table 3, and the purity and yield of the product are shown in Table 4.

[0065] in,

[0066]

[0067]

[0068]

[0069] Embodiment 2:

[0070] The process flow and steps are the same as those of Example 1, except that in step (3), the mass ratio of the extractant water to the feed stream (methanol-acetone azeotrope) is 2.

[0071] The operating conditions of each distillation tower are shown in Table 2, the composition of the tower top and tower bottom logistics are shown in Table 3, and the purity and yield of the product are shown in Table 4.

[0072] Example 3

[0073] The process and steps are the same as those in Example 1, except that in step (3), the acetone product obtained from the top of the extraction tower is not recycled back to the methanol-acetone azeotropic tower, and the membrane permeation flux of the pervaporation membrane module 2 in step (6) is 1.4 kg / m 2 / h, the water content of the oxide-water mixture is 3.7w% after dehydration and concentration by pervaporation.

[0074] The operating conditions of each distillation tower are shown in Table 2, the composition of the tower top and tower bottom logistics are shown in Table 3, and the purity and yield of the product are shown in Table 4.

[0075] Table 1 Composition of waste liquid containing oxides

[0076] Components Content wt% Acetaldehyde 5.1 Methanol 8.1 acetone 19.8 Other oxides 4.2 water 62.8

[0077] Table 2 Distillation tower operating conditions

[0078]

[0079]

[0080] Table 3 Composition of distillation tower top and bottom discharge

[0081]

[0082]

[0083] As can be seen from Table 3, the present invention transports part of the acetone at the top of the extractive distillation tower back to the methanol-acetone azeotropic tower, which can reduce the content of methanol and acetone in the bottom flow of the methanol-acetone azeotropic tower, improve the recovery rate of methanol and acetone, and further reduce the concentration of organic matter in the bottom flow of the oxide separation tower, thereby reducing the wastewater discharge rate.

[0084] Table 4 Separation and recovery product effects

[0085]

[0086]

[0087] It can be seen from the data in Table 4 that the method provided by the present invention can recover high-purity acetaldehyde, methanol and acetone products from oxide waste liquid. The purity of the three products is greater than 97%. Among them, when the recovery rate of acetaldehyde and acetone products is greater than 95%, the purity of the recovered products is greater than 98%, which is higher than most invention effects.

Claims

1. A method for recovering methanol and acetone from oxide waste liquid, characterized in that: include: The waste liquid containing oxides is sent to a light-removal tower, acetaldehyde material is obtained at the top of the tower, the bottom material enters a methanol-acetone azeotrope tower, methanol-acetone azeotrope is obtained at the top of the tower, the bottom material enters an oxide separation tower, an oxide-water mixture is obtained at the top of the tower, and the bottom material is water; the methanol-acetone azeotrope is sent to an extractive distillation tower, water is used as an extractant for extraction and separation, acetone product is obtained at the top of the tower, and the bottom material is a methanol-water mixture; the methanol-water mixture is subjected to pervaporation dehydration and refining to obtain a methanol product; the oxide-water mixture is subjected to pervaporation dehydration and concentration to obtain an oxide mixture fuel.

2. The method for recovering methanol and acetone in oxide waste liquid according to claim 1, characterized in that: In the oxide-containing waste liquid, the content of organic oxides is 20wt%-40wt%, the content of water is 60wt%-80wt%, and the organic oxides at least include methanol, acetone and acetaldehyde.

3. The method for recovering methanol and acetone in oxide waste liquid according to claim 2, characterized in that: The methanol content in the oxide-containing waste liquid is 7wt%-12wt%, the acetone content is 16wt%-20wt%, the acetaldehyde content is 2wt%-6wt%, and the content of other C1-C6 oxide mixtures is 1wt%-4wt%.

4. The method for recovering methanol and acetone in oxide waste liquid according to claim 1, characterized in that: The top discharge of the oxide separation tower is an oxide-water mixture, which contains 60-70wt% of the oxide mixture and 30-40wt% of water, wherein the C1-C6 oxide mixture includes methanol, ethanol, n-propanol, isopropanol, butanol, butanone, butanal, pentanone, hexanone and pentenone; the water content in the bottom discharge is >99wt%, and the oxide content is <1wt%.

5. The method for recovering methanol and acetone from oxide waste liquid according to any one of claims 1 to 4, characterized in that: The operating conditions of the lightness removal tower are: normal pressure operation, tower top temperature is below 20-28°C, tower bottom temperature is 50-73°C, and reflux ratio is 1-2; The operating conditions of the methanol-acetone azeotrope tower are: pressure of 0-0.2 MPa, tower top temperature of 55-90°C, tower bottom temperature of 70-120°C, and reflux ratio of 2-6; The operating conditions of the extractive distillation tower are: atmospheric pressure operation, the feed ratio of the extractant to the methanol-acetone azeotrope is 2-5, the reflux ratio is 2-4, the tower top temperature is 55-60°C, and the tower bottom temperature is 60-75°C; The operating conditions of the oxide separation tower are: normal pressure operation, reflux ratio of 1-3, tower top temperature of 70-100°C, and tower bottom temperature of 90-130°C.

6. The method for recovering methanol and acetone in oxide waste liquid according to claim 5, characterized in that: The acetone product obtained from the extractive distillation tower is partially recycled back to the methanol-acetone azeotrope tower for further treatment; Preferably, 25% to 50% of the acetone product is returned to the methanol-acetone azeotrope column.

7. The method for recovering methanol and acetone from oxide waste liquid according to claim 1, wherein the oxide-water mixture is dehydrated and concentrated using an inorganic molecular sieve membrane, the operating temperature is 60-80° C., the permeate side of the inorganic molecular sieve membrane is evacuated to -0.08 to -0.1 MPa, and the water content of the oxide mixture fuel obtained after dehydration is less than 5wt%; The methanol-water mixture is dehydrated and concentrated using an inorganic molecular sieve membrane at an operating temperature of 60-80°C. The permeation side of the inorganic molecular sieve membrane is evacuated to -0.08 to -0.1 MPa. The water content of the methanol product obtained after dehydration is less than 0.5wt%.

8. A separation system for recovering methanol and acetone from oxide waste liquid, used in the method for recovering methanol and acetone from oxide waste liquid according to any one of claims 1 to 7, characterized in that: It comprises a light removal tower, a methanol-acetone azeotrope tower, an oxide separation tower, an extractive distillation tower, a first membrane separator and a second membrane separator which are connected in sequence. The light removal tower is used to separate low-boiling organic oxides, and the bottom discharge of the tower is connected to the raw material inlet of the methanol-acetone azeotrope tower. The methanol-acetone azeotrope tower is used to separate the methanol-acetone azeotrope, the bottom discharge of the tower is connected to the raw material inlet of the oxide separation tower, and the top discharge of the methanol-acetone azeotrope tower is connected to the raw material inlet of the extraction distillation tower; The oxide separation tower is used to separate the remaining oxide mixture in the wastewater, the top discharge of the tower is connected to the first membrane separator, and the bottom discharge of the tower is discharged externally; The extractive distillation tower is used to separate methanol and acetone, the material discharged from the top of the tower is discharged externally, and the material discharged from the bottom of the tower is connected to the second membrane separator.

9. The separation system for recovering methanol and acetone in oxide waste liquid according to claim 8, characterized in that: The top discharge of the extractive distillation tower is communicated with the raw material inlet of the methanol-acetone azeotrope tower.

10. A method for treating waste liquid from methanol to ethylene, characterized in that: The reaction product of the methanol to olefins process enters a water washing tower, and the obtained wastewater containing organic oxides is sent to a stripping tower. The gas phase after stripping is cooled by heat exchange at the top of the tower to obtain an oxide-containing waste liquid; the oxide-containing waste liquid is treated by the method for recovering methanol and acetone in the oxide waste liquid as described in any one of claims 1 to 7 to obtain an acetone product and a methanol product.

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