Device and method for separating and refining 1, 3-butanediol

Abstract

The invention discloses a device and a method for separating and refining 1, 3-butanediol, and belongs to the field of chemical engineering. The device comprises an acetaldehyde reactor, a 3-hydroxybutyraldehyde rectifying tower, a hydrogenation reactor, a flash tank, a light component removal tower, a 1, 3-butanediol extraction tower, a 1, 3-butanediol product tank and a heavy component removal tower. By arranging the acetaldehyde rectifying tower and the dehydration unit, process water and acetaldehyde are recycled respectively, the utilization rate of reaction raw materials is increased, and the reaction cost is reduced; the separation and purification mode does not need to introduce make-up water into the 1, 3-butanediol product to separate the 1, 3-butanediol product, so that the step of distilling to remove water is omitted, and all the component materials only need to be heated and distilled once, so that the energy consumption is reduced; without using excessive acid and alkali materials in the whole process, equipment is not corroded, and the service life of the equipment is prolonged.

Description

Technical Field

[0001] The present application relates to an apparatus and method for separating and purifying 1,3 - butanediol, belonging to the field of chemical engineering. Background Art

[0002] 1,3 - Butanediol (1,3 - BDO) has characteristics such as good hygroscopicity, odorless, low toxicity, and good water solubility. It has the reactivity of dihydric alcohol and is used in the production of plasticizers, unsaturated polyester resins, industrial dehydrating agents, etc.; it can also be used as a humectant and softening agent for textiles, tobacco, and paper, an antibacterial agent for cheese or meat, etc.; it can also be used as a moisturizer in cosmetics and can be used in products such as lotion, cream, emulsion, gel, toothpaste, etc. The common industrial routes for producing 1,3 - butanediol mainly include: 1) acetaldehyde condensation and hydrogenation; 2) acrolein method; 3) biological fermentation method, etc. Each of these methods has its own advantages and disadvantages. The acetaldehyde condensation and hydrogenation method is currently the main technical route for producing 1,3 - butanediol. The yield of 1,3 - butanediol produced from acetaldehyde is relatively high, occupying the main market. The main reason for the lack of mature production technology in China at present is the limitation of the technology and process for separating and purifying 1,3 - butanediol.

[0003] The production of 1,3 - butanediol by acetaldehyde condensation and hydrogenation is divided into two steps. In the first step, acetaldehyde self - condenses to form 3 - hydroxybutyraldehyde; in the second step, 3 - hydroxybutyraldehyde is hydrogenated to form 1,3 - butanediol. 3 - Hydroxybutyraldehyde is unstable and is prone to dehydration to form crotonaldehyde under the conditions of acid, base, or heating. Crotonaldehyde contains both a carbonyl group and a C = C double bond, and under the conditions of the acetaldehyde condensation reaction, it can further condense with other aldehydes to form complex polymers. The existence of these by - products not only greatly reduces the product yield of 1,3 - butanediol but also seriously affects the quality indexes such as product purity, odor, and chromaticity.

[0004] Over the years, research teams at home and abroad led by DAICEL CHEMICAL INDUSTRIES have conducted a large amount of research on the separation and purification of 1,3 - butanediol. The main reports include adding an alkali metal salt to crude 1,3 - butanediol in EP1046628B1, heating and distilling, first separating the 1,3 - butanediol fraction, and the remaining alkali metal salt and high - boiling substances are used as residues. Then, low - boiling substances are distilled off from the 1,3 - butanediol fraction, and the content of high - boiling impurities in the obtained 1,3 - butanediol is below 0.5%; CN206396078U discloses a 1,3 - butanediol separation and purification device, which includes a rectifying column, a condenser, a separator, and a liquid pump, forming a circulating loop among them, and an evaporation device is provided in the rectifying column. Through multiple evaporation cycle treatments, 1,3 - butanediol with higher purity can be purified. Although these methods can all separate 1,3 - butanediol, the materials are repeatedly heated, resulting in high separation energy consumption, or serious equipment corrosion, or low economic benefits, greatly limiting the industrialization of the process flow. Summary of the Invention

[0005] In view of the technical status quo that when using an aqueous acetaldehyde solution as a raw material for catalytic condensation to prepare 1,3 - butanediol, the quality indicators such as product purity, color, and odor are not high, the intermediate products are unstable during the rectification separation process, and the separation energy consumption is too large, a device and method for separating and purifying 1,3 - butanediol with an aqueous acetaldehyde solution as the feed are proposed.

[0006] The present invention uses an aqueous acetaldehyde solution as a raw material and provides a device and method for separation and purification to obtain colorless, odorless, and high - purity 1,3 - butanediol, including 2 reactors, 5 rectification towers, and a dehydration unit. The 2 reactors are an acetaldehyde reactor and a hydrogenation reactor respectively. The 5 rectification towers are an acetaldehyde rectification tower, a 3 - hydroxybutyraldehyde rectification tower, a light - ends tower, a heavy - ends tower, and a 1,3 - butanediol extraction tower respectively. The dehydration unit is membrane dehydration, adsorption dehydration, or molecular sieve dehydration. The extractant is one or several of aliphatic hydrocarbon organic solvents such as cyclohexane, n - hexane, and petroleum ether.

[0007] According to the first aspect of the present application, a device for separating and purifying 1,3 - butanediol is provided.

[0008] A device for separating and purifying 1,3 - butanediol, the device includes: an acetaldehyde reactor, a 3 - hydroxybutyraldehyde rectification tower, a hydrogenation reactor, a flash tank, a light - ends tower, a 1,3 - butanediol extraction tower, a 1,3 - butanediol product tank, and a heavy - ends tower;

[0009] The outlet of the acetaldehyde reactor is connected to the inlet of the 3 - hydroxybutyraldehyde rectification tower;

[0010] The bottom outlet of the 3 - hydroxybutyraldehyde rectification tower is connected to the inlet of the hydrogenation reactor;

[0011] The outlet of the hydrogenation reactor is connected to the inlet of the flash tank;

[0012] The outlet of the flash tank is connected to the inlet of the light - ends tower;

[0013] The bottom outlet of the light - ends tower is connected to the side - line inlet of the 1,3 - butanediol extraction tower;

[0014] The top outlet of the 1,3 - butanediol extraction tower is connected to the inlet of the heavy - ends tower;

[0015] The bottom outlet of the 1,3 - butanediol extraction tower is connected to the 1,3 - butanediol product tank.

[0016] Optionally, the device further includes an acetaldehyde rectification tower;

[0017] The top outlet of the 3 - hydroxybutyraldehyde rectification tower is connected to the inlet of the acetaldehyde rectification tower;

[0018] The top outlet of the acetaldehyde rectification column is connected to the feed inlet of the acetaldehyde reactor.

[0019] Optionally, the device further includes a dehydration unit;

[0020] The bottom outlet of the acetaldehyde rectification column is connected to the dehydration unit.

[0021] Optionally, the dehydration unit is at least one of membrane dehydration, adsorption dehydration, and molecular sieve dehydration.

[0022] Optionally, the top outlet of the heavy component removal column is connected to the top feed inlet of the 1,3 - butanediol extraction column;

[0023] The bottom outlet of the heavy component removal column is connected to the solvent recovery tank.

[0024] As a preferred embodiment, a device for separating and purifying 1,3 - butanediol with an aqueous acetaldehyde solution as the feed includes 2 reactors, 5 rectification columns, and one dehydration unit. The outlet of the acetaldehyde reactor is connected to the feed inlet of the 3 - hydroxybutyraldehyde rectification column through a pipeline. The top outlet of the 3 - hydroxybutyraldehyde rectification column is connected to the feed inlet of the acetaldehyde rectification column, and the bottom outlet is connected to the feed inlet of the hydrogenation reactor. The outlet of the hydrogenation reactor is connected to the flash tank, and the outlet of the flash tank is connected to the feed inlet of the light component removal column through a pipeline. The bottom outlet of the light component removal column is connected to the side - line feed inlet of the 1,3 - butanediol extraction column. The top feed inlet of the 1,3 - butanediol extraction column is connected to the extractant circulation tank, and the bottom outlet is connected to the 1,3 - butanediol product tank. The top outlet of the 1,3 - butanediol extraction column is connected to the feed inlet of the heavy component removal column through a pipeline. The top outlet of the heavy component removal column is connected to the top feed inlet of the 1,3 - butanediol extraction column, and the bottom outlet is connected to the solvent recovery tank.

[0025] According to the second aspect of the present application, a method for separating and purifying 1,3 - butanediol is provided.

[0026] A method for separating and purifying 1,3 - butanediol, the method uses the device described above;

[0027] An aqueous acetaldehyde solution enters from the feed inlet of the acetaldehyde reactor, and the mixed solution of 3 - hydroxybutyraldehyde formed by acetaldehyde condensation enters the 3 - hydroxybutyraldehyde rectification column;

[0028] The 3 - hydroxybutyraldehyde taken out from the bottom of the 3 - hydroxybutyraldehyde rectification column enters the hydrogenation reactor for hydrogenation;

[0029] After all components in the hydrogenation reactor enter the flash tank to separate hydrogen, the liquid - phase component containing the 1,3 - butanediol mixed solution is transported to the light component removal column;

[0030] The light components including water, ethanol, and butanol are taken out from the top of the light component removal column, and the 1,3 - butanediol mixed solution taken out from the bottom enters the 1,3 - butanediol extraction column;

[0031] The extractant is fed into the top feed port of the 1,3 - butanediol extraction column. The 1,3 - butanediol product is withdrawn from the bottom of the 1,3 - butanediol extraction column and enters the 1,3 - butanediol product tank. The components including crotonaldehyde are withdrawn from the top of the column and enter the heavy - component removal column.

[0032] Optionally, the unreacted acetaldehyde and water withdrawn from the top of the 3 - hydroxybutyraldehyde column enter the acetaldehyde rectification column. Acetaldehyde is withdrawn from the top of the acetaldehyde rectification column and recycled back to the acetaldehyde reactor for use.

[0033] Optionally, the water withdrawn from the bottom of the acetaldehyde rectification column enters the dehydration unit for recycling.

[0034] Optionally, the extractant withdrawn from the top of the heavy - component removal column enters the 1,3 - butanediol extraction column for recycling;

[0035] Other heavy components are withdrawn from the bottom of the heavy - component removal column.

[0036] Optionally, the mass fraction of acetaldehyde in the fed aqueous acetaldehyde solution is 40 - 90%.

[0037] Optionally, the acetaldehyde reactor is equipped with a disk - shaped condensate water pipe.

[0038] Optionally, the reaction temperature of the acetaldehyde reactor is controlled at 20 - 35 °C.

[0039] Optionally, the operating conditions of the 3 - hydroxybutyraldehyde rectification column are: operating pressure 0.1 - 1 bar, top - column temperature 30 - 40 °C, bottom - column temperature 57 - 72 °C.

[0040] Optionally, the operating conditions of the hydrogenation reactor are: reaction pressure 20 - 60 bar, reaction temperature 55 - 80 °C.

[0041] Optionally, in the hydrogenation reactor, a fixed - bed continuous hydrogenation method is adopted. The solid catalyst is filled in the tubes, and the reaction materials flow from top to bottom. The reaction temperature is controlled by the circulating chilled water in the shell - side of the reactor.

[0042] Optionally, the operating conditions of the light - component removal column are: operating pressure 0.1 - 1 bar, top - column temperature 35 - 50 °C, bottom - column temperature 110 - 143 °C.

[0043] Optionally, the operating conditions of the 1,3 - butanediol extraction column are: operating pressure 0.1 - 1 bar, top - column temperature 20 - 30 °C, bottom - column temperature 120 - 155 °C.

[0044] Optionally, the operating conditions of the heavy - component removal column are: operating pressure 0.1 - 2 bar, top - column temperature 50 - 100 °C, bottom - column temperature 100 - 130 °C.

[0045] Optionally, the mass fraction of acetaldehyde in the aqueous acetaldehyde solution is 40-90%.

[0046] Optionally, the flow rate of the aqueous acetaldehyde solution is 15-50 kg / h.

[0047] Optionally, the extractant is one or more of aliphatic hydrocarbon organic solvents.

[0048] Optionally, the extractant is one or more of cyclohexane, n-hexane, and petroleum ether.

[0049] As a preferred embodiment, a method for separating and purifying 1,3-butanediol with an aqueous acetaldehyde solution as the feed is as follows: The aqueous acetaldehyde solution enters from the feed port of the acetaldehyde reactor, and the mixed solution of 3-hydroxybutyraldehyde formed by the condensation of acetaldehyde enters the 3-hydroxybutyraldehyde rectification column. The unreacted acetaldehyde and water are taken out from the top of the 3-hydroxybutyraldehyde rectification column and enter the acetaldehyde rectification column. The 3-hydroxybutyraldehyde taken out from the bottom of the column enters the hydrogenation reactor for hydrogenation. After all components in the hydrogenation reactor enter the flash tank to separate hydrogen, the liquid-phase component containing the 1,3-butanediol mixed solution is transported to the light component removal tower. The light components such as water, ethanol, and butanol are taken out from the top of the light component removal tower, and the 1,3-butanediol mixed solution is taken out from the bottom of the column. The 1,3-butanediol mixed solution taken out from the bottom of the column enters the 1,3-butanediol extraction column, and the extractant is added from the top feed port of the 1,3-butanediol extraction column. The 1,3-butanediol product taken out from the bottom of the 1,3-butanediol extraction column enters the product tank, and the components such as crotonaldehyde are taken out from the top of the column and enter the heavy component removal tower. The extractant taken out from the top of the heavy component removal tower enters the 1,3-butanediol extraction column to realize the recycling of the extractant, and other heavy components are taken out from the bottom of the heavy component removal tower.

[0050] The beneficial effects that can be produced by this application include:

[0051] The device and method for separating and purifying 1,3-butanediol provided by this application, by setting an acetaldehyde rectification column and a dehydration unit, realize the separate recycling of process water and acetaldehyde, improve the utilization rate of reaction raw materials, and reduce the reaction cost; the separation and purification method does not require adding supplementary water to the 1,3-butanediol product to make it phase-separate, saves the step of distilling and removing water, and each component material only needs to be heated and distilled once, saving energy consumption; no peracid or peralkali materials are used throughout the process, the equipment is not corroded, and the service life of the equipment is improved. Description of the Drawings

[0052] Figure 1 It is a schematic diagram of the device for separating and purifying 1,3-butanediol.

[0053] Among them, the reference numerals are as follows:

[0054] A Acetaldehyde reactor B 3-Hydroxybutyraldehyde rectification column

[0055] C Acetaldehyde rectification column D Dehydration unit

[0056] E Hydrogenation Reactor, F Flash Tank

[0057] G Light Component Removal Tower, H 1,3-Butanediol Extraction Tower

[0058] K Heavy Component Removal Tower

[0059] Material 1-1 is aqueous acetaldehyde solution, 1-2 is the mixed solution of 3-hydroxybutyraldehyde formed by acetaldehyde condensation reaction, 1-3 is the mixed solution of acetaldehyde, ethanol and water, 1-4 is the material without light components such as acetaldehyde, ethanol and water, 1-5 is the material of water and crotonaldehyde, 1-6 is the material of 1,3-butanediol to be refined, 1-7 is the material of 1,3-butanediol to be refined without hydrogen, 1-8 is the material without light components such as ethanol, butanol and water, 1-9 is the material of extractant and unreacted crotonaldehyde, 1-10 is other heavy components. Specific Embodiments

[0060] The present application will be described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0061] Unless otherwise specified, the raw materials in the embodiments of the present application are all purchased through commercial channels.

[0062] Unless otherwise specified, the test methods are all conventional methods, and the instrument settings are all the settings recommended by the manufacturer.

[0063] Example 1

[0064] As Figure 1 shown, it is a schematic diagram of the device for separating and refining 1,3-butanediol. A is an acetaldehyde reactor, B is a 3-hydroxybutyraldehyde rectification tower, C is an acetaldehyde rectification tower, D is a dehydration unit, E is a hydrogenation reactor, F is a flash tank, G is a light component removal tower, H is a 1,3-butanediol extraction tower, and K is a heavy component removal tower.

[0065] The outlet of the acetaldehyde reactor A is connected to the inlet of the 3-hydroxybutyraldehyde distillation column B through a pipeline. The top outlet of the 3-hydroxybutyraldehyde distillation column B is connected to the inlet of the acetaldehyde distillation column C. The bottom outlet of the 3-hydroxybutyraldehyde distillation column B is connected to the inlet of the hydrogenation reactor E. The outlet of the hydrogenation reactor E is connected to the inlet of the flash tank F through a pipeline. The outlet of the flash tank F is connected to the inlet of the light component removal tower G. The bottom outlet of the light component removal tower G is connected to the inlet of the 1,3-butanediol extraction tower H. The top outlet of the 1,3-butanediol extraction tower H is connected to the inlet of the heavy component removal tower K. The bottom outlet of the 1,3-butanediol extraction tower H is connected to the 1,3-butanediol product tank. The top outlet of the heavy component removal tower K is connected to the inlet of the 1,3-butanediol extraction tower H through a pipeline. The bottom outlet of the heavy component removal tower K is connected to the solvent recovery tank. The bottom outlet of the acetaldehyde distillation column C is connected to the dehydration unit D. Among them, a disk-shaped condensate water pipe is provided in the acetaldehyde reactor A. In the hydrogenation reactor E, a fixed-bed continuous hydrogenation method is adopted, and the solid catalyst is filled in the tubes, and the reaction materials flow from top to bottom, and the reaction temperature is controlled by the circulating chilled water in the shell side of the reactor.

[0066] The extractant can enter the 1,3-butanediol extraction tower H through the top outlet of the heavy component removal tower K, or can be added separately from the top inlet of the 1,3-butanediol extraction tower H.

[0067] Material 1-1 is an aqueous acetaldehyde solution, 1-2 is a mixed solution of 3-hydroxybutyraldehyde formed by acetaldehyde condensation reaction, 1-3 is a mixed solution of acetaldehyde, ethanol and water, 1-4 is a material without light components such as acetaldehyde, ethanol and water, 1-5 is a material of water and crotonaldehyde, 1-6 is a 1,3-butanediol material to be refined, 1-7 is a 1,3-butanediol material to be refined without hydrogen, 1-8 is a material without light components such as ethanol, butanol and water, 1-9 is a material of extractant and unreacted crotonaldehyde, 1-10 is other heavy components.

[0068] Material 1-1 enters the acetaldehyde reactor A. After the reaction, the material 1-2 enters the 3-hydroxybutyraldehyde distillation column B. The 1-3 material is taken out from the top of the distillation column B and enters the distillation column C. The 1-4 material is taken out from the bottom of the distillation column B and enters the hydrogenation reactor E. The outlet 1-6 of the hydrogenation reactor E enters the flash tank F. The outlet of the flash tank enters the light component removal tower G. The 1-8 material is taken out from the bottom of the light component removal tower G and enters the 1,3-butanediol extraction tower H. The 1-9 material is taken out from the top of the 1,3-butanediol extraction tower H and enters the heavy component removal tower K. The 1,3-butanediol product is taken out from the bottom of the 1,3-butanediol extraction tower H. Among them, the extractant taken out from the top of the heavy component removal tower K enters the 1,3-butanediol extraction tower H for recycling. Acetaldehyde is taken out from the top of the distillation column C and recovered and returned to the acetaldehyde reactor A for use. Water taken out from the bottom of the acetaldehyde distillation column C enters the dehydration unit D for recycling. The dehydration unit D is specifically membrane dehydration.

[0069] Using this method for separation, material 1-1 is an aqueous solution with 80% acetaldehyde content, the raw material flow rate is 35 kg / h, and the reaction temperature of acetaldehyde reactor A is 25°C. The operating pressure of light component removal tower G is 0.2 bar, the top temperature is 40°C, and the bottom temperature is 117°C; the operating pressure of 3-hydroxybutyraldehyde distillation tower B is 0.1 bar, the top temperature is 34°C, and the bottom temperature is 62°C; the reaction pressure of hydrogenation reactor E is 40 bar, and the reaction temperature is 70°C; the operating pressure of 1,3-butanediol extraction tower H is 0.1 bar, the top temperature is 22°C, and the bottom temperature is 125°C; the operating pressure of heavy component removal tower K is 0.2 bar, the top temperature is 80°C, and the bottom temperature is 113°C. The extractant is n-hexane and petroleum ether, and the mass ratio is 5:1.

[0070] The separated 1,3-butanediol is colorless and odorless, and the purity by gas chromatography is 99.8%.

[0071] Example 2

[0072] In this example, the separation device and method are the same as those in Example 1. Material 1-1 is an aqueous solution with 60% acetaldehyde, the raw material flow rate is 40 kg / h, and the reaction temperature of acetaldehyde reactor A is 28°C. The operating pressure of light component removal tower G is 0.2 bar, the top temperature is 38°C, and the bottom temperature is 123°C; the operating pressure of 3-hydroxybutyraldehyde distillation tower B is 0.1 bar, the top temperature is 37°C, and the bottom temperature is 66°C; the reaction pressure of hydrogenation reactor E is 50 bar, and the reaction temperature is 70°C; the operating pressure of 1,3-butanediol extraction tower H is 0.1 bar, the top temperature is 25°C, and the bottom temperature is 120°C; the operating pressure of heavy component removal tower K is 0.2 bar, the top temperature is 75°C, and the bottom temperature is 120°C. The extractant is cyclohexane.

[0073] The separated 1,3-butanediol is colorless and odorless, and the purity by gas chromatography is 99.6%.

[0074] The above are only several embodiments of the present application, and do not impose any form of limitation on the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the relevant art can make some changes or modifications within the scope of the technical solution of the present application by using the disclosed technical content, which are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A device for separating and refining 1,3-butanediol, characterized in that: The device comprises: an acetaldehyde reactor, a 3-hydroxybutyraldehyde distillation tower, a hydrogenation reactor, a flash tank, a light removal tower, a 1,3-butanediol extraction tower, a 1,3-butanediol product tank, and a heavy removal tower; The discharge port of the acetaldehyde reactor is connected to the feed port of the 3-hydroxybutyraldehyde distillation tower; The tower bottom discharge port of the 3-hydroxybutyraldehyde rectification tower is connected to the feed port of the hydrogenation reactor; The discharge port of the hydrogenation reactor is connected to the feed port of the flash tank; The discharge port of the flash tank is connected to the feed port of the light removal tower; The tower bottom discharge port of the lightness removal tower is connected to the side line feed port of the 1,3-butanediol extraction tower; The top discharge port of the 1,3-butanediol extraction tower is connected to the feed port of the deweighting tower; The tower bottom discharge port of the 1,3-butanediol extraction tower is connected to the 1,3-butanediol product tank.

2. The device according to claim 1, characterized in that The device also includes an acetaldehyde distillation tower; The top discharge port of the 3-hydroxybutyraldehyde distillation tower is connected to the feed port of the acetaldehyde distillation tower; The top discharge port of the acetaldehyde distillation tower is connected to the feed port of the acetaldehyde reactor.

3. The device according to claim 2, characterized in that The device also includes a dehydration unit; The tower bottom discharge port of the acetaldehyde distillation tower is connected to the dehydration unit.

4. The device according to claim 1, characterized in that The top discharge port of the deweighting tower is connected to the top feed port of the 1,3-butanediol extraction tower; The tower bottom discharge port of the deweighting tower is connected to the solvent recovery tank.

5. A method for separating and refining 1,3-butanediol, characterized in that: The method adopts the device according to any one of claims 1 to 4; The acetaldehyde aqueous solution enters from the feed port of the acetaldehyde reactor, and the 3-hydroxybutyraldehyde mixed solution generated by acetaldehyde condensation enters the 3-hydroxybutyraldehyde distillation tower; The 3-hydroxybutyraldehyde extracted from the bottom of the 3-hydroxybutyraldehyde distillation tower enters the hydrogenation reactor for hydrogenation; After all components in the hydrogenation reactor enter the flash tank to separate hydrogen, the liquid phase components containing the 1,3-butanediol mixed liquid are transported to the light removal tower; The light components including water, ethanol and butanol are extracted from the top of the light removal tower, and the 1,3-butanediol mixed liquid extracted from the bottom of the tower enters the 1,3-butanediol extraction tower; The extractant is added from the feed port at the top of the 1,3-butanediol extraction tower, the 1,3-butanediol product is extracted from the bottom of the 1,3-butanediol extraction tower and enters the 1,3-butanediol product tank, and the components including crotonaldehyde are extracted from the top of the tower and enter the deweighting tower.

6. The method according to claim 5, characterized in that The unreacted acetaldehyde and water are taken out from the top of the 3-hydroxybutyraldehyde tower and enter into the acetaldehyde distillation tower. The acetaldehyde taken out from the top of the acetaldehyde distillation tower is recovered and returned to the acetaldehyde reactor for use.

7. The method according to claim 6, characterized in that The water produced from the bottom of the acetaldehyde distillation tower enters the dehydration unit for recycling.

8. The method according to claim 5, characterized in that The extractant taken out from the top of the deweighting tower is recycled into the 1,3-butanediol extraction tower; Other heavy components are taken out from the bottom of the deweighting tower.

9. The method according to claim 5, characterized in that The reaction temperature of the acetaldehyde reactor is controlled at 20-35°C; The operating conditions of the 3-hydroxybutyraldehyde distillation tower are: operating pressure 0.1-1 bar, tower top temperature 30-40°C, tower bottom temperature 57-72°C; The operating conditions of the hydrogenation reactor are: reaction pressure 20-60 bar, reaction temperature 55-80°C; The operating conditions of the light removal tower are: operating pressure 0.1-1 bar, tower top temperature 35-50°C, tower bottom temperature 110-143°C; The operating conditions of the 1,3-butanediol extraction tower are: operating pressure 0.1-1 bar, tower top temperature 20-30°C, tower bottom temperature 120-155°C; The operating conditions of the deweighting tower are: operating pressure 0.1-2 bar, tower top temperature 50-100°C, tower bottom temperature 100-130°C.

10. The method according to claim 5, characterized in that The mass fraction of acetaldehyde in the acetaldehyde aqueous solution is 40-90%; The flow rate of the acetaldehyde aqueous solution is 15-50 kg / h.

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