Device and method for recovering acetaldehyde in production process of 1, 3-butanediol

Abstract

The invention discloses a device and a method for recovering acetaldehyde in a 1, 3-butanediol production process, and belongs to the field of fine chemical engineering. The device comprises a raw material pump, a preheater, a rectifying tower, a falling film reboiler, a tower bottom circulating pump, a tower bottom cooler, a tower top primary condenser, a reflux ratio distributor, a tower top secondary condenser, a tower top product tank, a tower top transfer tank, a tower bottom product tank, a tower bottom transfer tank, a vacuum condenser, a vacuum pump inlet liquid separation tank, a high vacuum unit and a vacuum pump outlet liquid separation tank. The horizontal condenser is directly mounted at the top of the rectifying tower, so that the device has the advantages of simple structure, convenience in operation, small pipeline loss, high vacuum degree and the like. The invention also discloses a method for recovering acetaldehyde in the production process of 1, 3-butanediol by adopting the device. Compared with the prior art, the method provided by the invention adopts a method of matching falling film evaporation with reduced-pressure cryogenic treatment, so that thermal decomposition of 3-hydroxybutyraldehyde can be avoided, and low-temperature efficient recovery of acetaldehyde is realized. And continuous production conditions are provided.

Description

Technical Field

[0001] The present application relates to an acetaldehyde recovery device and method in the production process of 1,3-butanediol, belonging to the field of fine chemicals. Background Art

[0002] 1,3-Butylene Glycol (1,3-BDO) is a widely used chemical product with high added value and a gradually expanding market. At present, the mainstream process for producing 1,3-butanediol is to use acetaldehyde as raw material, first using a water-soluble liquid base such as NaOH as a catalyst to generate 3-hydroxybutyraldehyde through a self-condensation reaction in an aqueous solution; then using Raney nickel (RaneyNi) as a catalyst, hydrogenation is performed to generate 1,3-butanediol. In the process of preparing 1,3-butanediol by acetaldehyde condensation hydrogenation, a large amount of acetaldehyde will be left after the first condensation reaction is completed, and the existing technology uses a variety of means to recycle acetaldehyde. For example, CN112390713A reported the recovery of acetaldehyde by nitrogen stripping and pressurized cooling; CN111704532A reported the low-temperature and efficient recovery of acetaldehyde by the cooperation of a bubbling tower and an absorption tower; CN105585448A reported the recovery of acetaldehyde by flash evaporation at a temperature of 80-100°C after the condensation reaction. Summary of the invention

[0003] In view of the common problems of low acetaldehyde recovery rate and high energy consumption in the prior art, the present invention adopts a falling film evaporation method combined with reduced pressure deep cooling, which can efficiently recover acetaldehyde while ensuring the stable existence of 3-hydroxybutyraldehyde, and is suitable for continuous industrial production.

[0004] According to a first aspect of the present application, an acetaldehyde recovery device in a 1,3-butanediol production process is provided.

[0005] An acetaldehyde recovery device in a 1,3-butanediol production process, the device comprising:

[0006] Raw material pump, preheater, distillation tower, falling film reboiler, bottom circulation pump, bottom cooler, top primary condenser, reflux ratio distributor, top secondary condenser, top product tank, top transfer tank, bottom product tank, bottom transfer tank, vacuum condenser, vacuum pump inlet separator tank, high vacuum unit, vacuum pump outlet separator tank.

[0007] Optionally, the feed pump is connected to a preheater, and the preheater is connected to the middle of the distillation tower;

[0008] The falling film reboiler is connected to the lower part of the distillation tower;

[0009] The falling film reboiler is connected to a tower bottom circulation pump;

[0010] The tower bottom circulation pump is connected to the bottom of the distillation tower;

[0011] The tower bottom cooler is connected to the tower bottom circulation pump, the tower bottom product tank is connected to the tower bottom cooler, and the tower bottom transfer tank is connected to the tower bottom product tank;

[0012] The tower top primary condenser is directly installed on the top of the distillation tower;

[0013] The reflux ratio distributor is connected to the upper part of the distillation tower, the tower top secondary condenser is connected to the reflux ratio distributor, the tower top product tank is connected to the tower top secondary condenser, and the tower top transfer tank is connected to the tower top product tank;

[0014] The vacuum condenser is connected to the first-level condenser at the top of the tower, the product tank at the top of the tower, and the product tank at the bottom of the tower. The vacuum pump inlet separator tank is connected to the vacuum condenser. The high vacuum unit is connected to the vacuum pump inlet separator tank. The vacuum pump outlet separator tank is connected to the high vacuum unit.

[0015] Optionally, the falling film reboiler is used to supply heat to the bottom of the distillation tower;

[0016] The falling film reboiler adopts a heat-conducting oil furnace for heating, and a bottom circulation pump is used to make the mixed material flow from top to bottom in a thin film state along the inner wall of the falling film tube.

[0017] The bottom of the distillation tower adopts a falling film reboiler for heating, and the falling film reboiler adopts a heat transfer oil furnace for heating. The mixed material flows from top to bottom in a thin film state along the inner wall of the falling film tube through a bottom circulation pump. The heat transfer coefficient is high, the material residence time is short, and the decomposition of 3-hydroxybutyraldehyde is avoided.

[0018] Optionally, the first-stage condenser at the top of the tower is a horizontal condenser, which is directly installed on the top of the distillation tower, and has the characteristics of simple structure, convenient operation, small pipeline loss and high vacuum degree.

[0019] Optionally, the distillation tower is a packed tower with a total packing height of 2.5 to 4 m.

[0020] Optionally, the total height of the packing is 3 m, and the heights of the rectifying section and the stripping section are 1.5 m each.

[0021] Optionally, the packing type is BX500.

[0022] Optionally, the first-stage condenser at the top of the tower and the second-stage condenser at the top of the tower are cooled by a refrigerator.

[0023] Optionally, a reflux ratio distributor is provided at the top of the distillation tower, and the reflux ratio is adjustable from 0 to 99.

[0024] Optionally, the device is equipped with a high vacuum unit with a maximum vacuum degree of less than 50Pa.

[0025] Optionally, the inlet and outlet liquid separation tanks of the high vacuum unit in the device are cooled by a refrigerator jacket to protect the vacuum pump.

[0026] According to a second aspect of the present application, a method for recovering acetaldehyde in a 1,3-butanediol production process is provided.

[0027] A method for recovering acetaldehyde in a 1,3-butanediol production process, using the above-mentioned acetaldehyde recovery device in a 1,3-butanediol production process for separation, comprising:

[0028] S1. Cooling the mixture containing acetaldehyde and 3-hydroxybutyraldehyde to 5-10° C.;

[0029] S2. Use a raw material pump to transport the mixed material to the preheater. After being preheated in the preheater, the mixed material enters the middle of the distillation tower. The temperature of the preheater is controlled at 15-25°C.

[0030] S3, control the bottom temperature of the distillation tower to 40-70°C, the frequency conversion output of the bottom circulation pump to 60-80, the top temperature to 30-60°C, and the top pressure to 10-40KPa;

[0031] S4, control the outlet temperature of the first-stage condenser at the top of the tower to -30~-10℃, the reflux ratio to 10~40, and the temperature of the second-stage condenser at the top of the tower to -25℃~-15℃. At this time, the top product tank collects acetaldehyde, which is transferred through the top transfer tank, and the bottom product tank collects 3-hydroxybutyraldehyde, which is transferred through the bottom product tank.

[0032] The beneficial effects of this application include:

[0033] The acetaldehyde recovery device and method in the 1,3-butanediol production process provided by the present application can avoid the thermal decomposition of 3-hydroxybutyraldehyde and realize the low-temperature and efficient recovery of acetaldehyde. The acetaldehyde recovery rate is higher than 90%, and the 3-hydroxybutyraldehyde retention rate is higher than 97%. The product quality meets industrial requirements and has the conditions for continuous production. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a flow chart of an acetaldehyde recovery device in a 1,3-butanediol production process in one embodiment of the present application.

[0035] Description of reference numerals:

[0036] 1-Raw material pump 2-Preheater 3-Distillation tower

[0037] 4- Falling film reboiler 5- Bottom circulation pump 6- Bottom cooler

[0038] 7-First-stage condenser at the top of the tower 8-Reflux ratio distributor 9-Second-stage condenser at the top of the tower

[0039] 10-Tower top product tank 11-Tower top transfer tank

[0040] 12-tower bottom product tank 13-tower bottom transfer tank

[0041] 14- Vacuum condenser 15- Vacuum pump inlet separator

[0042] 16- High vacuum unit 17- Vacuum pump outlet liquid separation tank DETAILED DESCRIPTION

[0043] The application is described in detail below in conjunction with the examples, but the application is not limited to these examples. The endpoints and any values ​​of the scope disclosed in this article are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. These numerical ranges should be considered as specifically disclosed in this article.

[0044] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0045] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0046] As a specific implementation method, an acetaldehyde recovery device in a 1,3-butanediol production process includes: a raw material pump, a preheater, a distillation tower, a falling film reboiler, a bottom circulation pump, a bottom cooler, a top primary condenser, a reflux ratio distributor, a top secondary condenser, a top product tank, a top transfer tank, a bottom product tank, a bottom transfer tank, a vacuum condenser, a vacuum pump inlet separator tank, a high vacuum unit, and a vacuum pump outlet separator tank.

[0047] Further, the raw material pump is connected to the preheater, and the preheater is connected to the middle part of the distillation tower; the falling film reboiler is connected to the lower part of the distillation tower; the falling film reboiler is connected to the bottom circulation pump; the bottom circulation pump is connected to the bottom of the distillation tower; the bottom cooler is connected to the bottom circulation pump, the bottom product tank is connected to the bottom cooler, and the bottom transfer tank is connected to the bottom product tank; the top primary condenser is directly installed on the top of the distillation tower; the reflux ratio distributor is connected to the upper part of the distillation tower, the top secondary condenser is connected to the reflux ratio distributor, the top product tank is connected to the top secondary condenser, and the top transfer tank is connected to the top product tank; the vacuum condenser is connected to the top primary condenser, the top product tank, and the bottom product tank, the vacuum pump inlet separator is connected to the vacuum condenser, the high vacuum unit is connected to the vacuum pump inlet separator, and the vacuum pump outlet separator is connected to the high vacuum unit.

[0048] Furthermore, the distillation tower is a packed tower, the packing type is BX500, the total packing height is 3m, and the heights of the distillation section and the stripping section are 1.5m respectively.

[0049] Furthermore, the bottom of the distillation tower adopts a falling film reboiler for heating, and the falling film reboiler adopts a heat transfer oil furnace for heating. The mixed material is made to flow from top to bottom in a thin film state along the inner wall of the falling film tube through a bottom circulation pump. The heat transfer coefficient is high, the material residence time is short, and the decomposition of 3-hydroxybutyraldehyde is avoided.

[0050] Furthermore, the first-stage condenser at the top of the tower is a horizontal condenser, which is directly installed at the top of the distillation tower and has the characteristics of simple structure, convenient operation, small pipeline loss and high vacuum degree.

[0051] Furthermore, a reflux ratio distributor is arranged at the top of the distillation tower, and the reflux ratio is adjustable from 0 to 99.

[0052] As a specific implementation method, a method for recovering acetaldehyde in a 1,3-butanediol production process uses the above-mentioned acetaldehyde recovery device in a 1,3-butanediol production process for separation, specifically as follows:

[0053] (1) cooling the mixture mainly containing acetaldehyde and 3-hydroxybutyraldehyde to 5-10° C.;

[0054] (2) Use a raw material pump to transport the mixed material to the preheater, and after being preheated in the preheater, it enters the middle of the distillation tower, and the preheater temperature is controlled at 15-25°C;

[0055] (3) The bottom temperature of the distillation tower is controlled at 40-70°C, the frequency conversion output of the circulation pump is controlled at 60-80, the top temperature is controlled at 30-60°C, and the top pressure is controlled at 10-40KPa;

[0056] (4) The outlet temperature of the first-stage condenser at the top of the tower is controlled at -30 to -10°C, the reflux ratio is 10 to 40, and the temperature of the second-stage condenser at the top of the tower is controlled at -25°C to -15°C. At this time, the top product tank collects acetaldehyde, which is transferred through the top transfer tank, and the bottom product tank collects 3-hydroxybutyraldehyde, which is transferred through the bottom product tank.

[0057] The mixed material containing acetaldehyde and 3-hydroxybutyraldehyde is the product of condensation reaction, with the concentration of acetaldehyde being 5-80%, 3-hydroxybutyraldehyde being 15-60%, and the content of other substances being 3-40%.

[0058] The analysis method in the examples of this application is as follows:

[0059] The water content and acid content in the recovered acetaldehyde can be quantitatively analyzed by gas chromatography, and the concentrations of acetaldehyde and 3-hydroxybutyraldehyde in the material can be measured by the standard curve method.

[0060] The acetaldehyde recovery rate is (acetaldehyde in the top product of the distillation tower / acetaldehyde in the mixed material)×100%, and the retention rate of 3-hydroxybutyraldehyde is (3-hydroxybutyraldehyde in the bottom product of the distillation tower / 3-hydroxybutyraldehyde in the mixed material).

[0061] Example 1

[0062] like Figure 1 As shown, it is a flow chart of the acetaldehyde recovery device in the production process of 1,3-butanediol, and the device includes: a raw material pump 1, a preheater 2, a distillation tower 3, a falling film reboiler 4, a bottom circulation pump 5, a bottom cooler 6, a top primary condenser 7, a reflux ratio distributor 8, a top secondary condenser 9, a top product tank 10, a top transfer tank 11, a bottom product tank 12, a bottom transfer tank 13, a vacuum condenser 14, a vacuum pump inlet separator 15, a high vacuum unit 16, and a vacuum pump outlet separator 17.

[0063] The raw material pump 1 is connected to the preheater 2, the preheater 2 is connected to the middle part of the distillation tower 3, the falling film reboiler 4 and the bottom circulation pump 5 are connected to the lower part of the distillation tower 3, the bottom cooler 6 is connected to the bottom circulation pump 5, the bottom product tank 12 is connected to the bottom cooler 6, the bottom transfer tank 13 is connected to the bottom product tank 12, the top primary condenser 7 is directly installed on the top of the distillation tower 3, the reflux ratio distributor 8 is connected to the upper part of the tower, the top secondary condenser 9 is connected to the reflux ratio distributor 8, and the top product tank 12 is connected to the top secondary condenser 9. The tower top transfer tank 11 is connected to the tower top product tank 10, the vacuum condenser 14 is connected to the tower top primary condenser 9, the tower top product tank 10, and the tower bottom product tank 12, the vacuum pump inlet separator tank 15 is connected to the vacuum condenser 14, the high vacuum unit 16 is connected to the vacuum pump inlet separator tank 15, and the vacuum pump outlet separator tank 17 is connected to the high vacuum unit 16.

[0064] The distillation tower 3 is a packed tower, the packing type is BX500, the total packing height is 3m, and the height of the distillation section and the stripping section are 1.5m respectively.

[0065] The first-stage condenser 7 at the top of the tower is a horizontal condenser, which is directly installed at the top of the distillation tower and has the characteristics of simple structure, convenient operation, small pipeline loss and high vacuum degree.

[0066] The tower top primary condenser 7 and the tower top secondary condenser 9 are cooled by a refrigerator.

[0067] The bottom of the distillation tower 3 is heated by a falling film reboiler 4, which is heated by a heat transfer oil furnace. The bottom circulation pump 5 allows the mixed material to flow from top to bottom along the inner wall of the falling film tube in a thin film state, with a high heat transfer coefficient and a short material residence time, thereby avoiding the decomposition of 3-hydroxybutyraldehyde.

[0068] The device is equipped with a high vacuum unit 16, and the ultimate vacuum degree is less than 50Pa.

[0069] The inlet and outlet liquid separation tanks (vacuum pump inlet liquid separation tank 15 and vacuum pump outlet liquid separation tank 17) of the high vacuum unit 16 are cooled by refrigerator jackets to protect the vacuum pump.

[0070] A reflux ratio distributor 8 is arranged at the top of the distillation tower 3, and the reflux ratio is adjustable from 0 to 99.

[0071] Example 2

[0072] A method for recovering acetaldehyde in a 1,3-butanediol production process, using the acetaldehyde recovery device in a 1,3-butanediol production process described in Example 1 for separation, specifically as follows:

[0073] (1) The mixed material contains 45% acetaldehyde, 50% 3-hydroxybutyraldehyde and 5% other substances. The mixed material is cooled to 10°C and transported to the preheater 2 by the raw material pump 1. After the preheater 2 is heated to 20°C, it enters the middle of the distillation tower 3. The feed rate of the mixed material is 5 kg / h.

[0074] (2) The tower bottom circulation pump 5 is put into use, and the frequency conversion setting is 70%. The tower top primary condenser 7 is put into use, and the temperature is set to -30°C. The tower top secondary condenser 9 is put into use, and the temperature is set to -25°C. The high vacuum unit 16 is started, and the pressure of the distillation tower 3 is controlled to 30 kPa. The reflux ratio is controlled to 30 by the reflux ratio distributor 8.

[0075] (3) The heat transfer oil unit was put into use to control the bottom temperature of distillation tower 3 to 60°C.

[0076] (4) The top temperature of distillation tower 3 is controlled to be 43°C.

[0077] (5) A large amount of acetaldehyde gas evaporates from the mixed material at the bottom of the distillation tower 3, and contacts the reflux liquid phase from bottom to top in countercurrent, and the gas-liquid two phases continuously transfer mass and heat, and finally reach equilibrium.

[0078] (6) The water content and acid content in the recovered acetaldehyde are quantitatively analyzed by gas chromatography, and the concentrations of acetaldehyde and 3-hydroxybutyraldehyde in the material can be measured by the standard curve method. The purity of the recovered acetaldehyde is ≥99%. The amount of cyclic acetaldehyde is 2kg / h, and the acetaldehyde recovery rate is 90%. The amount of 3-hydroxybutyraldehyde at the bottom of the tower is 2.4kg / h, and the retention rate of 3-hydroxybutyraldehyde is ≥97%.

[0079] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An acetaldehyde recovery device in the production process of 1,3-butanediol, characterized in that: The device comprises: Raw material pump, preheater, distillation tower, falling film reboiler, bottom circulation pump, bottom cooler, top primary condenser, reflux ratio distributor, top secondary condenser, top product tank, top transfer tank, bottom product tank, bottom transfer tank, vacuum condenser, vacuum pump inlet separator tank, high vacuum unit, vacuum pump outlet separator tank.

2. The device according to claim 1, characterized in that The raw material pump is connected to a preheater, and the preheater is connected to the middle part of the distillation tower; The falling film reboiler is connected to the lower part of the distillation tower; The falling film reboiler is connected to a tower bottom circulation pump; The tower bottom circulation pump is connected to the bottom of the distillation tower; The tower bottom cooler is connected to the tower bottom circulation pump, the tower bottom product tank is connected to the tower bottom cooler, and the tower bottom transfer tank is connected to the tower bottom product tank; The tower top primary condenser is directly installed on the top of the distillation tower; The reflux ratio distributor is connected to the upper part of the distillation tower, the tower top secondary condenser is connected to the reflux ratio distributor, the tower top product tank is connected to the tower top secondary condenser, and the tower top transfer tank is connected to the tower top product tank; The vacuum condenser is connected to the first-level condenser at the top of the tower, the product tank at the top of the tower, and the product tank at the bottom of the tower. The vacuum pump inlet separator tank is connected to the vacuum condenser. The high vacuum unit is connected to the vacuum pump inlet separator tank. The vacuum pump outlet separator tank is connected to the high vacuum unit.

3. The device according to claim 2, characterized in that The falling film reboiler is used to supply heat to the bottom of the distillation tower; The falling film reboiler adopts a heat-conducting oil furnace for heating, and a bottom circulation pump is used to make the mixed material flow from top to bottom in a thin film state along the inner wall of the falling film tube.

4. The device according to claim 2, characterized in that The first-stage condenser at the top of the tower is a horizontal condenser, which is directly installed on the top of the distillation tower.

5. The device according to claim 2, characterized in that The distillation tower is a packed tower, and the total height of the packing is 2.5 to 4 meters; Preferably, the total height of the packing is 3m, and the height of the rectifying section and the stripping section are 1.5m each; Preferably, the filler type is BX500.

6. The device according to claim 2, characterized in that The first-stage condenser at the top of the tower and the second-stage condenser at the top of the tower are cooled by a refrigerator.

7. The device according to claim 2, characterized in that A reflux ratio distributor is arranged on the top of the distillation tower, and the reflux ratio is adjustable from 0 to 99.

8. The device according to claim 2, characterized in that The device is equipped with a high vacuum unit with an ultimate vacuum degree of less than 50Pa.

9. The device according to claim 2, characterized in that The inlet and outlet liquid separation tanks of the high vacuum unit in the device are cooled by refrigerator jackets to protect the vacuum pump.

10. A method for recovering acetaldehyde in a 1,3-butanediol production process, characterized in that: The acetaldehyde recovery device in the 1,3-butanediol production process according to any one of claims 1 to 9 is used for separation, comprising: S1. Cooling the mixture containing acetaldehyde and 3-hydroxybutyraldehyde to 5-10° C.; S2. Use a raw material pump to transport the mixed material to the preheater. After being preheated in the preheater, the mixed material enters the middle of the distillation tower. The temperature of the preheater is controlled at 15-25°C. S3, control the bottom temperature of the distillation tower to 40-70°C, the frequency conversion output of the bottom circulation pump to 60-80, the top temperature to 30-60°C, and the top pressure to 10-40KPa; S4, control the outlet temperature of the first-stage condenser at the top of the tower to -30~-10℃, the reflux ratio to 10~40, and the temperature of the second-stage condenser at the top of the tower to -25℃~-15℃. At this time, the top product tank collects acetaldehyde, which is transferred through the top transfer tank, and the bottom product tank collects 3-hydroxybutyraldehyde, which is transferred through the bottom product tank.

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