CN115814449A

CN115814449A - Method and system for rectifying 1, 4-butanediol and byproduct n-butanol

Info

Publication number: CN115814449A
Application number: CN202211624003.3A
Authority: CN
Inventors: 林发现; 刘新波; 李浩楠; 孙凯; 周鹏飞; 郭欣; 王垚
Original assignee: Wuheng Chemical Co ltd
Current assignee: Wuheng Chemical Co ltd
Priority date: 2022-12-16
Filing date: 2022-12-16
Publication date: 2023-03-21

Abstract

The invention discloses a method and a system for rectifying 1, 4-butanediol and a byproduct n-butyl alcohol. The method and the system comprise a residue removing unit, a BDO rectifying unit and an n-butyl alcohol purifying unit, wherein related equipment comprises a residue removing tower, a BDO pretreatment tower, a BDO finished product tower, an n-butyl alcohol pretreatment tower, an n-butyl alcohol finished product tower, a tower top reflux pump, a tower bottom circulating pump, a heat exchanger, a tower top condenser, a tower bottom reboiler, a chromatograph feeding condenser, a chromatograph and the like. The invention has simple flow and convenient operation, adopts the thermal coupling process, ensures the purity of the product to reach the standard, and reduces the consumption of public works such as steam, cooling water and the like.

Description

Method and system for rectifying 1, 4-butanediol and byproduct n-butanol

Technical Field

The invention belongs to the technical field of rectification, and particularly relates to a method and a system for rectifying 1, 4-butanediol and a byproduct n-butanol.

Background

1, 4-Butanediol (BDO) is used as an important organic chemical raw material, and has wide application and high added value. The downstream products of the method are widely applied to various fields of solvents, medicines, fibers, cosmetics, pesticides and the like. In recent years, n-butanol has attracted much attention worldwide as a new type of automobile fuel additive and substitute, and has a higher mixing ratio, a higher energy density, and a lower heat of vaporization than ethanol. At present, the global BDO production process routes are totally 5, which are respectively as follows: acetylenic aldehyde process, butadiene acetyloxidation process, dichlorobutene hydrolysis process, allylol hydroformylation process, and maleic anhydride hydrogenation process. At present, the production route of BDO in China is mainly an acetylenic aldehyde method and a maleic anhydride hydrogenation method, but the maleic anhydride hydrogenation method is only suitable for areas with low butane price, so that the route has limited applicability, and the BDO production method in China is mainly the acetylenic aldehyde method.

Chinese patent CN209940868U proposes a rectifying device in the process of producing high-purity 1, 4-butanediol, the utility model discloses a concentration tower, salt tower, low boiling tower, high boiling tower that connect gradually, this utility model patent equipment is few, reasonable in design, easy operation, move equipment few, wearing and tearing are few, have reduced investment cost to a certain extent. However, the concentration tower, the salt tower, the low-boiling tower and the high-boiling tower involved in the rectification process designed in the patent are respectively connected with corresponding tower kettle reboilers, the tower top is connected with a tower top cooler, heat required by the tower kettle is provided by steam, and cold required by the tower top is provided by cooling water, so that the consumption of public works in the whole rectification process is increased undoubtedly.

Chinese patent CN107129424A discloses a purification system of 1, 4-butanediol and n-butanol, and the system provided by the invention comprises a pre-desilication aluminum system, a dehydration system, a butanediol system and a n-butanol system which are sequentially communicated. In the system proposed in this patent, the raw material is treated by a pre-desilication aluminum system to facilitate stable operation of a subsequent dehydration system. In addition, the system realizes the deep recovery of 1, 4-butanediol in light and heavy components and n-butanol in fusel in the process, the maximum utilization of resources is achieved, and the heavy component organic waste liquid in the system is sent to waste acid for incineration, so that fuel is saved and the dangerous organic waste liquid is treated. However, the butanediol and n-butanol purification system has a too long flow, needs more dynamic equipment and static equipment such as a rectifying tower, a flash tank, a heat exchanger, a storage tank, a pump and the like, has higher investment cost, and brings certain difficulty to workers in actual production operation.

Disclosure of Invention

The invention aims to solve the defects in the patents and designs a rectification method and a rectification system for preparing 1, 4-butanediol and a byproduct n-butanol. The invention realizes the purpose of rectifying and purifying 1, 4-butanediol and n-butanol by the following operations.

A rectification system for 1, 4-butanediol and byproduct n-butanol is characterized by comprising a residue removal tower, a BDO pretreatment tower and a BDO finished product tower which are sequentially connected. The top of the residue removing tower is sequentially connected with a first inter-stream heat exchanger, an auxiliary condenser at the top of the residue removing tower, a reflux pump at the top of the residue removing tower and a BDO pretreatment tower. The top of the BDO pretreatment tower is connected with a primary condenser, a secondary condenser and a BDO pretreatment tower top reflux pump, and the bottom of the BDO pretreatment tower is sequentially connected with a BDO pretreatment tower kettle circulating pump, a BDO pretreatment tower kettle reboiler and a BDO finished product tower. And the top of the BDO finished product tower is sequentially connected with a second inter-stream heat exchanger, a BDO finished product tower top auxiliary condenser and a BDO finished product tower top reflux pump.

Further, the system also comprises an n-butanol pretreatment tower, a layer analyzer and an n-butanol finished product tower which are connected in sequence. A side extraction outlet of the n-butanol pretreatment tower is sequentially connected with a feeding condenser of a chromatographic apparatus and the chromatographic apparatus; the upper part of the layer analyzer is connected with an organic phase feeding pump and is connected to a n-butanol finished product tower, and the lower part of the layer analyzer is connected with a water phase feeding pump and is connected to a n-butanol pretreatment tower. And the top of the n-butanol finished product tower is connected to a feeding condenser of the chromatographic apparatus.

Furthermore, the rectifying section of the residue removing tower adopts a tower plate, and the stripping section is a packed tower. The residue removing tower has top temperature of 130-150 deg.C, pressure of 0.001-0.01MPa, bottom temperature of 155-175 deg.C, and bottom pressure of 0.1-0.4MPa. The BDO pretreatment tower and the BDO finished product tower are packed towers.

Further, the top of the BDO pretreatment tower adopts two-stage condensation.

Further, the n-butanol pretreatment tower is a plate tower; the n-butanol finished product tower is a packed tower.

The invention has the beneficial effects that: the system has simple process flow and convenient operation, adopts a thermal coupling process, and reduces the consumption of public works such as steam, cooling water and the like while ensuring the product purity to reach the standard.

Drawings

FIG. 1 is a schematic diagram of a method and a system for rectifying 1, 4-butanediol and n-butanol as a byproduct according to the present invention.

The system comprises a residue removing tower, a 2.BDO pretreatment tower, a 3.BDO finished product tower, a 4. N-butyl alcohol pretreatment tower, a 5. N-butyl alcohol finished product tower, a 6. Stream-to-stream heat exchanger I, a 7. Stream-to-stream heat exchanger II, an 8. N-butyl alcohol pretreatment tower kettle auxiliary reboiler, a 9. Residue removing tower top auxiliary condenser, a 10. N-butyl alcohol finished product tower kettle auxiliary reboiler, a 11.BDO finished product tower top auxiliary condenser, a 12. Chromatograph feeding condenser, a 13. Chromatographic separator, a 14. N-butyl alcohol pretreatment tower top condenser, a 15. N-butyl alcohol pretreatment tower top reflux pump, a 16. N-butyl alcohol pretreatment tower kettle circulating pump, a 17. Water phase feeding pump, an 18. Organic phase feeding pump, a 19. N-butyl alcohol finished product tower kettle circulating pump, a 20. Residue removing tower kettle circulating pump, a 21. Residue removing tower kettle reboiler, a 22. Residue removing tower top reflux pump, a 23.BDO pretreatment tower top circulating pump, a 24.BDO pretreatment tower kettle reboiler, a 25. First-stage condenser, a 26. Second-stage condenser, a 27.BDO finished product tower top reflux pump, a 28.BDO finished product tower reflux pump, a 29.BDO finished product tower top reflux tower reboiler, a 30.BDO finished product tower reboiler; s1, BDO solution to be purified, and S2, n-butyl alcohol solution to be purified.

Detailed Description

The following detailed description of the preferred embodiment of the present invention, taken in conjunction with the accompanying fig. 1, enables those skilled in the art to better understand the advantages and features of the present invention, and thereby define the scope of the invention more clearly.

A rectification system for 1, 4-butanediol and by-product n-butanol is characterized in that: comprises a residue removing tower 1, a BDO pretreatment tower 2 and a BDO finished product tower 3 which are connected in sequence. The top of the residue removing tower 1 is sequentially connected with a first inter-stream heat exchanger 6, an auxiliary condenser 9 at the top of the residue removing tower, a reflux pump 22 at the top of the residue removing tower and a BDO pretreatment tower 2. The top of the BDO pretreatment tower 2 is connected with a first-stage condenser 25, a second-stage condenser 26 and a BDO pretreatment tower top reflux pump 27, and the bottom of the BDO pretreatment tower kettle circulating pump 23, a BDO pretreatment tower kettle reboiler 24 and a BDO finished product tower 3 are sequentially connected. And the top of the BDO finished product tower 3 is sequentially connected with a second inter-stream heat exchanger 7, a BDO finished product tower top auxiliary condenser 11 and a BDO finished product tower top reflux pump 30.

Preferably, the system also comprises an n-butanol pretreatment tower 4, a chromatograph 13 and an n-butanol finished product tower 5 which are connected in sequence. And a side extraction outlet of the n-butanol pretreatment tower 4 is sequentially connected with a chromatograph feeding condenser 12 and a chromatograph 13. The upper part of the layer analyzer 13 is connected with an organic phase feeding pump 18 and is connected to the n-butanol finished product tower 5, and the lower part is connected with a water phase feeding pump 17 and is connected to the n-butanol pretreatment tower 4. The top of the n-butanol finished product tower 5 is connected to a feeding condenser 12 of the chromatographic device.

Preferably, the rectifying section of the residue removing tower 1 is a plate type, and the stripping section is a packed tower. The temperature of the top of the residue removing tower 1 is 130-150 ℃, the pressure is 0.001-0.01Mpa, the temperature of the bottom of the tower is 155-175 ℃, and the pressure of the bottom of the tower is 0.1-0.4Mpa. The BDO pretreatment tower 2 and the BDO finished product tower 3 are packed towers.

Preferably, the top of the BDO pretreatment tower 2 adopts two-stage condensation.

Preferably, the n-butanol pretreatment tower 4 is a plate tower, and the n-butanol finished product tower 5 is a packed tower.

The following is a preferred embodiment of the present invention.

The BDO solution S1 to be purified from the previous unit comprises 95 mass percent of BDO content, 3 mass percent of heavy component organic waste liquid and trace water, n-butyl alcohol, gamma-butyrolactone and other components, enters a residue removing tower, heavy component residues are removed from the bottom of the tower, BDO and other substances are evaporated from the top of the tower, a steam stream at the top of the residue removing tower exchanges heat with a stream at the bottom of the n-butyl alcohol pretreatment tower, a part of materials flow back to the residue removing tower from the top of the tower, a part of materials are used as a feed of the BDO pretreatment tower, the temperature at the top of the residue removing tower is 143 ℃, the pressure is-0.095 MpaG, the temperature at the bottom of the tower is 169 ℃, and the pressure is 0.3MpaG.

The BDO content of the material from the top of the residue removing tower is about 96.5 percent, the material enters a BDO pretreatment tower, after rectification treatment, the material condensed by a first-level condenser at the top of the tower is used as a reflux material of the tower, the gas not condensed by the first-level condenser enters a second-level condenser for secondary condensation treatment, and the material condensed by the second-level condenser mainly comprises light components such as 2-methyl 2, 4-pentanediol, gamma-butyrolactone and the like, and is discharged into a light component storage tank. And separating a material with the BDO content of about 98 percent from the bottom of the BDO pretreatment tower to be used as a feed of a BDO finished product tower. After the material at the bottom of the tower enters a BDO finished product tower, heavy components which are not completely separated in a residue removing unit are separated from the bottom of the BDO finished product tower through rectification treatment, and a BDO product with the mass concentration of 99.7 percent and meeting the national standard requirement is obtained at the top of the tower. Wherein the tower top steam of the BDO finished product tower exchanges heat with the tower bottom material of the n-butanol finished product tower, so that the tower top steam of the BDO finished product tower is condensed, one part of the steam flows back, and the other part of the steam is taken as a BDO product to be extracted. The top temperature of the BDO pretreatment tower is 138 ℃, the pressure is-0.095 MpaG, the bottom temperature is 155 ℃, and the pressure is 0.001MpaG. The tower top temperature of the BDO finished product tower is 144 ℃, the pressure is-0.097 MpaG, the tower bottom temperature is 158 ℃, and the pressure is 0.002MpaG.

The solution S2 to be purified of the n-butanol from the previous unit comprises 96.5% of water by mass and 2.5% of n-butanol by mass, and also comprises trace methanol, propanol, tetrahydrofuran and other components, and is used as a feed of a butanol purification unit. After layering, the content of the n-butyl alcohol in the organic phase is about 73 percent, the content of the water is about 22 percent, the content of the propanol is 2 percent, and the organic phase also contains a trace of light components such as methanol, tetrahydrofuran and the like, and is used as a feed of a finished product tower of the n-butyl alcohol, the content of the n-butyl alcohol in the water phase is about 7.5 percent, the content of the water is 89 percent, the content of the methanol is about 2 percent, and a trace of light components, the organic phase returns to the n-butyl alcohol pretreatment tower again to recover the n-butyl alcohol in the water phase, and an n-butyl alcohol product is distilled from the bottom of the finished product tower. The temperature of the top of the n-butanol pretreatment tower is 89 ℃, the pressure is 0.002MpaG, the temperature of the bottom of the tower is 104 ℃, the pressure is 0.015MpaG, the temperature of the top of the n-butanol finished product tower is 102 ℃, the pressure is 0.005MpaG, the temperature of the bottom of the tower is 119 ℃, and the pressure is 0.007MpaG.

The above description is only an embodiment of the present invention, and is not intended to limit the scope of the present invention, and all equivalent flow transformations made by the present specification and the attached drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A method and a system for rectifying 1, 4-butanediol and a byproduct n-butanol are characterized in that: the device comprises a residue removing tower (1), a BDO pretreatment tower (2) and a BDO finished product tower (3) which are sequentially connected, wherein the top of the residue removing tower (1) is sequentially connected with a first inter-stream heat exchanger (6), a residue removing tower top auxiliary condenser (9), a residue removing tower top reflux pump (22) and the BDO pretreatment tower (2), the top of the BDO pretreatment tower (2) is connected with a first-stage condenser (25), a second-stage condenser (26) and a BDO pretreatment tower top reflux pump (27), the bottom of the BDO pretreatment tower top reflux pump is sequentially connected with a BDO pretreatment tower kettle circulating pump (23), a BDO pretreatment tower kettle reboiler (24) and the BDO finished product tower (3), and the top of the BDO finished product tower (3) is sequentially connected with a second inter-stream heat exchanger (7), a BDO finished product tower top auxiliary condenser (11) and a BDO finished product tower top reflux pump (30).

2. The method and system for rectifying 1, 4-butanediol and n-butanol as a byproduct according to claim 1, wherein: the system also comprises an n-butanol pretreatment tower (4), a chromatograph (13) and an n-butanol finished product tower (5) which are sequentially connected, wherein a side extraction port of the n-butanol pretreatment tower (4) is sequentially connected with a chromatograph feeding condenser (12) and a chromatograph (13), the upper part of the chromatograph (13) is connected with an organic phase feeding pump (18) and connected to the n-butanol finished product tower (5), the lower part of the chromatograph (13) is connected with a water phase feeding pump (17) and connected to the n-butanol pretreatment tower (4), and the top of the n-butanol finished product tower (5) is connected to the chromatograph feeding condenser (12).

3. The method and system for rectifying 1, 4-butanediol and n-butanol as a byproduct according to claim 1, wherein: the distillation section of the residue removing tower (1) is a plate type, the stripping section is a packed tower, the temperature of the top of the residue removing tower (1) is 130-150 ℃, the pressure is 0.001-0.01Mpa, the temperature of the bottom of the tower is 155-175 ℃, the pressure of the bottom of the tower is 0.1-0.4Mpa, and the BDO pretreatment tower (2) and the BDO finished product tower (3) are packed towers.

4. The method and system for rectifying 1, 4-butanediol and n-butanol as a byproduct according to claim 1, wherein: and the top of the BDO pretreatment tower (2) adopts two-stage condensation.

5. The method and system for rectifying 1, 4-butanediol and n-butanol as a byproduct according to claim 2, wherein: the n-butanol pretreatment tower (4) is a plate tower, and the n-butanol finished product tower (5) is a packed tower.