A system and method for rectification purification of 1,4-butanediol

Abstract

The application discloses a system and method for 1,4-butanediol rectification purification, which comprises the following steps: 1,4-butanediol crude material enters a tar column to be subjected to rectification separation to obtain first gas phase material containing light components and 1,4-butanediol and first liquid phase material containing heavy components and 1,4-butanediol; the first gas phase material from the tar column enters a light component removal column to be subjected to rectification to remove TBA and low-boiling impurities in the 1,4-butanediol of the first gas phase material, so as to obtain light component gas phase and second liquid phase material containing 1,4-butanediol after light component removal; the first liquid phase material from the tar column and the second liquid phase material from the light component removal column enter a heavy component removal column to be subjected to rectification to remove high-boiling impurities in the 1,4-butanediol of the first liquid phase material and the second liquid phase material, so as to obtain light component gas phase, third liquid phase material and refined 1,4-butanediol product. The application can reduce operation energy consumption and improve the upper limit of operation of each rectification column by simultaneously removing salt and heavy components.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and specifically to a system and method for the distillation and purification of 1,4-butanediol. Background Technology

[0002] In the process of producing 1,4-butanediol (BDO) via the acetylacetonate method, butynediol is hydrogenated to BDO under the action of a catalyst, while byproducts include butanol, propanol, methanol, γ-hydroxybutyric acid, butenediol, 2(4-hydroxybutoxy)tetrahydrofuran (TBA), high-boiling substances, and salts. In the BDO concentration process, lighter components such as butanol, propanol, methanol, and water are removed to obtain a crude BDO solution with a BDO content of approximately 95 wt%. The crude BDO solution is then sent to the BDO purification system for separation and purification to obtain purified BDO with a content of 99.7 wt%. This process is the main energy consumption in the operation of the BDO unit. Traditional distillation processes have problems such as high operating load and high energy consumption of each distillation column. Under high-load operating conditions, abnormal operating conditions such as high pressure drop and flooding of the distillation columns are prone to occur.

[0003] Patent CN114669073A discloses a 1,4-butanediol multi-effect distillation system and a multi-effect distillation process. This system includes dehydration, desalting, residue removal, product purification, and heat optimization systems. Through multi-effect distillation and heat optimization within the system, it achieves low-carbon and low-energy consumption optimization of the distillation process. This system has high heat integration and low unit energy consumption; however, double-effect distillation requires a high-pressure distillation column, which operates at high temperatures, easily causing BDO polymerization and impurities, leading to substandard product quality.

[0004] Patent CN1114853573A provides a system and method for separating and purifying 1,4-butanediol. By using a composite extractant to increase the relative volatility of 1,4-butanediol and 2-(4-hydroxybutoxy)tetrahydrofuran, BDO with a purity of over 99.99% can be obtained, reducing BDO loss, achieving high separation efficiency and high product purity. However, introducing a new extractant requires additional equipment and may result in extractant impurities entering the BDO product.

[0005] Patent CN107778141A discloses a purification method for 1,4-butanediol. This method includes contacting crude 1,4-butanediol containing aldehyde and / or acetal impurities with a silver-supported resin catalyst under hydrogen-exposed conditions to obtain purified 1,4-butanediol with a color intensity less than 10 APHA. While this method can purify crude 1,4-butanediol containing aldehyde and / or acetal impurities and reduce its color intensity, it only applies to aldehyde-containing systems and cannot separate and purify impurities within the BDO system itself.

[0006] Currently, most BDO refining processes employ a process of first desalting and then removing impurities, which leads to multiple vaporizations of heavy component impurities in the distillation system, increasing energy consumption and causing excessive operating loads on each column, making it impossible to achieve stable operation under high load conditions. Summary of the Invention

[0007] In view of this, the main objective of the present invention is to provide a system and method for the distillation purification of 1,4-butanediol, which can reduce operating energy consumption and increase the operating limit of each distillation column by simultaneously desalting and removing heavy components.

[0008] To achieve the above-mentioned objective, the first aspect of the present invention provides a system for the distillation and purification of 1,4-butanediol, comprising:

[0009] A tar tower is used to receive crude 1,4-butanediol and to distill and separate its light and heavy components to obtain a first gaseous material containing light components and 1,4-butanediol and a first liquid material containing heavy components and 1,4-butanediol.

[0010] The light component removal tower is used to receive the first gaseous material from the tar tower and to distill off TBA and low-boiling impurities in 1,4-butanediol, to obtain a light component gaseous material and a second liquid phase material containing the light component removed 1,4-butanediol.

[0011] The heavy phase removal tower is used to receive the first liquid phase material from the tar tower and the second liquid phase material from the light phase removal tower, and to distill and remove high-boiling impurities from 1,4-butanediol to obtain light component gas phase, third liquid phase material and refined 1,4-butanediol product.

[0012] Furthermore, the system of the present invention also includes a heat exchanger connected to the de-heavy tower for receiving the third liquid phase material from the de-heavy tower and separating it into a gas phase rich in 1,4-butanediol and a liquid phase containing heavy components and salt impurities.

[0013] Furthermore, the tar tower, the light oil removal tower, and the heavy oil removal tower all include a feed inlet, a gas phase outlet at the top of the tower, and a liquid phase outlet at the bottom of the tower. Preferably, they also include a gas phase condensation and reflux device at the top of the tower, and the gas phase outlet at the top of the tower is connected to the gas phase condensation and reflux device at the top of the tower.

[0014] Furthermore, the feed inlet of the tar tower is connected to the feed pipeline carrying crude 1,4-butanediol, the bottom liquid outlet of the tar tower is connected to the feed inlet of the heavy phase removal tower, and the top vapor phase condensation reflux device of the tar tower is connected to the feed inlet of the light phase removal tower.

[0015] Furthermore, the liquid phase outlet at the bottom of the light component removal tower is connected to the feed inlet of the heavy component removal tower, and the gas phase condensation and reflux device at the top of the light component removal tower is connected to the light component pipeline.

[0016] Furthermore, the heat exchanger includes a feed inlet, a gas phase outlet, and a liquid phase outlet; the bottom liquid phase outlet of the deweight removal tower is connected to the feed inlet of the evaporator, the gas phase outlet of the heat exchanger is connected to the feed inlet of the deweight removal tower, and the liquid phase outlet of the heat exchanger is connected to the heavy weight distribution pipeline.

[0017] Furthermore, a deweighting tower pump is installed on the recombination pipeline.

[0018] Furthermore, the deweighting tower also includes a side outlet for obtaining purified 1,4-butanediol product.

[0019] Furthermore, each of the above-top gas phase condensation and reflux devices includes a condenser, a reflux tank, and a reflux pump; the above-top gas phase outlet is connected to the condenser and the reflux tank, and then refluxes back to the tar tower, light oil removal tower, or heavy oil removal tower via the reflux pump.

[0020] A second aspect of the present invention provides a method for the distillation purification of 1,4-butanediol, comprising the following steps:

[0021] The crude 1,4-butanediol feedstock is fed into the tar tower for distillation and separation to obtain a first gaseous material containing light components and 1,4-butanediol, and a first liquid material containing heavy components and 1,4-butanediol.

[0022] The first gaseous material from the tar tower enters the light phase removal tower for distillation to remove TBA and low-boiling impurities from the 1,4-butanediol in the first gaseous material, resulting in a light component gaseous material and a second liquid phase material containing the light-removed 1,4-butanediol.

[0023] The first liquid phase material from the tar tower and the second liquid phase material from the light phase removal tower enter the heavy phase removal tower for distillation to remove high-boiling impurities from the 1,4-butanediol in the first and second liquid phase materials, yielding a light component gas phase, a third liquid phase material, and a refined 1,4-butanediol product.

[0024] Furthermore, the method of the present invention further includes: the third liquid phase material from the deweighting tower enters the heat exchanger for separation to obtain a gas phase rich in 1,4-butanediol and a liquid phase containing heavy components and salt impurities.

[0025] Furthermore, the gas phase obtained from the heat exchanger then enters the deweighting tower.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The tar tower of this invention is used for the preliminary separation of light and heavy components from crude 1,4-butanediol (BDO). The first gaseous material, containing light components and a small amount of BDO, obtained through distillation, enters a light component removal tower. The first liquid phase, containing heavy components and most of the BDO, enters a heavy component removal tower. The first gaseous material from the tar tower enters the light component removal tower for distillation to remove TBA and low-boiling impurities from the 1,4-butanediol, yielding a light component gaseous phase and a second liquid phase containing the light-removed 1,4-butanediol. The first liquid phase from the tar tower and the second liquid phase from the light component removal tower enter the heavy component removal tower for distillation to remove high-boiling impurities from the 1,4-butanediol, yielding a light component gaseous phase, a third liquid phase, and a purified 1,4-butanediol product. The advantages of the above process of this invention compared to existing purification processes are:

[0028] (1) Through this invention, the tar tower can initially enrich heavy components and salts in the tower bottom, reduce the multiple vaporization of heavy component impurities, and save energy consumption.

[0029] (2) Through this invention, the operating load of the light tower can be reduced, which is conducive to stable operation under high load conditions and increases the operating margin of the light tower.

[0030] (3) If the content of light and heavy components of the raw material changes, the product quality can be qualified by modifying the top and bottom extraction ratio of the tar tower without adding new equipment.

[0031] (4) Without increasing energy consumption, the present invention can further improve the purity of the product.

[0032] Therefore, this invention, considering the impurity composition of the BDO system, employs a three-tower distillation process design consisting of a tar tower, a light oil removal tower, and a heavy oil removal tower. This effectively increases the processing capacity of the distillation towers and reduces system energy consumption. Using the method of this invention, under the condition of BDO purity of 99.7wt%, energy consumption is 2800KW lower than that of the traditional process. The system of this invention can be widely applied in BDO refining processes, saving energy without increasing equipment investment, resulting in significant economic benefits.

[0033] Other features and advantages of the present invention will be described in detail through the following specific embodiments. Attached Figure Description

[0034] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0035] Figure 1 This is a schematic diagram of the 1,4-butanediol distillation and purification system provided in Example 1 of this application.

[0036] Figure 2 A schematic diagram of the 1,4-butanediol distillation and purification system provided for Comparative Example 1.

[0037] Figure 3 A schematic diagram of the 1,4-butanediol distillation and purification system provided for Comparative Example 2.

[0038] Figure 4 A schematic diagram of the 1,4-butanediol distillation and purification system provided for Comparative Example 3.

[0039] Figure 5 A schematic diagram of the 1,4-butanediol distillation and purification system provided for Comparative Example 4.

[0040] Figure 6 A schematic diagram of the 1,4-butanediol distillation and purification system provided for Comparative Example 5.

[0041] Labeling explanation: T1 for tar tower, T2 for light oil removal tower, T3 for heavy oil removal tower, E1, E2, E3 for condensers, and E4 for scraped film evaporator. Detailed Implementation

[0042] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0043] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0044] Unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and connections within two components or interactions between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0045] This invention provides a system for the distillation and purification of 1,4-butanediol, comprising:

[0046] A tar tower is used to receive crude 1,4-butanediol and to distill and separate its light and heavy components to obtain a first gaseous material containing light components and 1,4-butanediol and a first liquid material containing heavy components and 1,4-butanediol.

[0047] The light component removal tower is used to receive the first gaseous material from the tar tower and to distill off TBA and low-boiling impurities in 1,4-butanediol, to obtain a light component gaseous material and a second liquid phase material containing the light component removed 1,4-butanediol.

[0048] The heavy phase removal tower is used to receive the first liquid phase material from the tar tower and the second liquid phase material from the light phase removal tower, and to distill and remove high-boiling impurities from 1,4-butanediol to obtain light component gas phase, third liquid phase material and refined 1,4-butanediol product.

[0049] In this invention, 1,4-butanediol crude is a crude product containing 1,4-butanediol obtained by hydrogenation and dehydration of 1,4-butynediol. For ease of description, it is referred to as BDO crude. The crude product is separated using a tar tower, which is connected to both a light component removal tower and a heavy component removal tower. In some examples, after preliminary separation in the tar tower, the BDO crude product is collected at the top of the tower, containing water, TBA, other light components, and a small amount of BDO, i.e., the liquid phase after condensation of the first gaseous phase; and at the bottom of the tower, BDO and heavy components, i.e., the first liquid phase.

[0050] In this invention, a light component removal tower receives and separates the liquid phase after condensation of the first gaseous material. In some examples, the bottom of the light component removal tower is connected to a heavy component removal tower. The top of the tower collects a mixture of light components containing BDO, TBA, and water, i.e., the liquid phase after condensation of the light component gaseous phase; the bottom of the tower collects a BDO solution with high purity (99.5 wt%) containing TBA and heavy component impurities, i.e., the second liquid phase, to recover the BDO after light component removal.

[0051] In this invention, the heavy component removal tower receives and separates the first liquid phase material from the tar tower and the second liquid phase material from the light component removal tower. In some examples, the top of the heavy component removal tower yields a mixture of light components containing BDO, TBA, and water, i.e., the liquid phase after the light component gas phase is condensed; the side stream yields a high-purity (99.7 wt%) BDO product; and the bottom of the tower yields a BDO solution with a high content of heavy components, i.e., the third liquid phase material.

[0052] The system of the present invention also includes a heat exchanger connected to the de-heavy column for receiving the third liquid phase material from the de-heavy column and separating it into a gas phase rich in 1,4-butanediol and a liquid phase containing heavy components and salt impurities. In some examples, the heat exchanger is a scraped film evaporator (which receives the third liquid phase material from the de-heavy column), and after separation, the gas phase is extracted as BDO rich in heavy components; the liquid phase is extracted as heavy components and salt impurities with low BDO content.

[0053] It is understood that the tar tower, light oil removal tower, and heavy oil removal tower all include a feed inlet, a top vapor phase outlet, and a bottom liquid phase outlet. Preferably, they also have a top vapor phase condensation and reflux device, such as... Figure 1 The device shown in E1, E2 or E3 has a gas phase outlet at the top of the tower connected to the gas phase condensation and reflux device at the top of the tower. After the gas phase enters the condenser, part of it is extracted and part of it is refluxed.

[0054] In some examples, the deweighting tower also includes a side feed outlet for obtaining purified 1,4-butanediol product.

[0055] In some examples, the top vapor phase condensation and reflux device includes a condenser, a reflux tank, and a reflux pump; the top vapor phase outlet is connected to the condenser and the reflux tank, and then refluxes back to the tar tower, light oil removal tower, or heavy oil removal tower via the reflux pump.

[0056] Preferably, the reflux trough includes a noncondenser gas outlet.

[0057] Preferably, the system further includes a water seal tank and a non-condensable gas pipeline, with all non-condensable gas outlets connected to the water seal tank via the non-condensable gas pipeline.

[0058] It is understood that the system of the present invention also includes pipelines for containing and transporting the various components, exemplarily including inlet pipelines, light component pipelines, heavy component pipelines, BDO product pipelines, etc.

[0059] In some examples, the feed inlet of the tar tower is connected to the feed pipeline carrying crude 1,4-butanediol, the bottom liquid outlet of the tar tower is connected to the feed inlet of the heavy phase removal tower, and the top vapor phase condenser reflux device of the tar tower is connected to the feed inlet of the light phase removal tower.

[0060] In some examples, the bottom liquid outlet of the light component removal tower is connected to the feed inlet of the heavy component removal tower, and the top vapor condensation reflux device of the light component removal tower is connected to the light component pipeline.

[0061] In some examples, the vapor phase at the top of the tar tower is partially refluxed after condensation and partially sent to the light oil removal tower; the vapor phase at the top of the heavy oil removal tower is completely refluxed after condensation.

[0062] It is understood that the heat exchanger includes a feed inlet, a gas phase outlet, and a liquid phase outlet; the bottom liquid phase outlet of the deweight removal tower is connected to the feed inlet of the heat exchanger, the gas phase outlet of the heat exchanger is connected to the feed inlet of the deweight removal tower, and the liquid phase outlet of the heat exchanger is connected to the heavy weight distribution pipeline.

[0063] Preferably, a deweighting tower pump is installed on the recombination pipeline.

[0064] A second aspect of the present invention provides a method for the distillation purification of 1,4-butanediol, comprising the following steps:

[0065] The crude 1,4-butanediol feedstock is fed into the tar tower for distillation and separation to obtain a first gaseous material containing light components and 1,4-butanediol, and a first liquid material containing heavy components and 1,4-butanediol.

[0066] The first gaseous material from the tar tower enters the light phase removal tower for distillation to remove TBA and low-boiling impurities from the 1,4-butanediol in the first gaseous material, resulting in a light component gaseous material and a second liquid phase material containing the light-removed 1,4-butanediol.

[0067] The first liquid phase material from the tar tower and the second liquid phase material from the light phase removal tower enter the heavy phase removal tower for distillation to remove high-boiling impurities from the 1,4-butanediol in the first and second liquid phase materials, yielding a light component gas phase, a third liquid phase material, and a refined 1,4-butanediol product.

[0068] Furthermore, the process also includes the following steps: the third liquid phase material from the de-heavy tower enters a heat exchanger for separation, resulting in a gas phase rich in 1,4-butanediol and a liquid phase containing heavy components and salt impurities.

[0069] Furthermore, the gas phase obtained from the heat exchanger enters the de-weighting tower, and the liquid phase obtained enters the re-weighting pipeline.

[0070] The present invention will be further described below with reference to the embodiments:

[0071] Example 1

[0072] like Figure 1 As shown, the system for the distillation purification of 1,4-butanediol includes a tar tower, a light oil removal tower, a heavy oil removal tower, and a scraped film evaporator.

[0073] BDO crude material undergoes initial separation in the tar tower. The composition of the crude BDO is: 94 wt% 1,4-butanediol, 0.2 wt% TBA, 5.3 wt% light components, and 0.5 wt% remaining heavy components. The top of the tar tower yields water, TBA, other light components (those with lower boiling points than BDO, excluding water and TBA), and a small amount of BDO. The bottom of the tar tower yields BDO and other heavy components (those with higher boiling points than BDO). The tar tower packing height is 23 theoretical plates, the operating pressure is 5 kPa, the reflux ratio is 0.58, the top temperature is 133℃, and the bottom temperature is 157℃. The heavy component content in the top sample of the tar tower is less than 0.3 wt%, and the light component content in the bottom sample is less than 0.1 wt%.

[0074] The tar from the top of the tar tower, after condensation and partial reflux, enters the light component removal tower for separation. The top of the light component removal tower yields BDO-rich waste liquid, while the bottom yields a BDO solution with a purity of 99.5 wt%. The light component removal tower has a packing height of 30 theoretical plates, an operating pressure of 5.1 kPa, a reflux ratio of 21.7, a top temperature of 142°C, and a bottom temperature of 160°C.

[0075] The bottom products from the tar tower and the light component removal tower are fed into the heavy component removal tower for separation. A small amount of BDO waste liquid containing light components is collected from the top of the heavy component removal tower, while a side stream of BDO product with a purity of 99.7 wt% is collected. A BDO solution with a high heavy component content is collected from the bottom of the heavy component removal tower. The packing height of the heavy component removal tower is 43 theoretical plates, the operating pressure is 6.2 kPa, the reflux ratio is 5630, the top temperature is 152℃, and the bottom temperature is 169℃.

[0076] The bottom product from the deweighting tower enters the scraped-film evaporator for separation. The vapor phase from the scraped-film evaporator, containing a higher concentration of BDO, returns to the bottom of the deweighting tower, while the liquid phase from the scraped-film evaporator consists of heavier components with lower BDO content and salt impurities. The scraped-film evaporator operates at a pressure of 13 kPa and a temperature of 170 °C.

[0077] Comparative Example 1

[0078] like Figure 2 As shown, the system for the distillation purification of 1,4-butanediol includes a tar tower, a light oil removal tower, a heavy oil removal tower, and a scraped film evaporator.

[0079] BDO crude feedstock underwent initial separation in the tar tower. The composition of the BDO crude feedstock was: 94 wt% 1,4-butanediol, 0.2 wt% TBA, 5.3 wt% light components, and 0.5 wt% remaining heavy components. The top of the tower yielded water, TBA, other light components, and most of the BDO; the bottom of the tower yielded BDO and other heavy components. The tar tower packing height was 23 theoretical plates, the operating pressure was 5 kPa, the reflux ratio was 0.16, the top temperature was 144℃, and the bottom temperature was 168℃. The heavy component content in the top sample was less than 0.3 wt%, and the light component content in the bottom sample was less than 0.1 wt%.

[0080] The tar from the top of the tar tower, after condensation and partial reflux, enters the light component removal tower for separation. The top of the tower yields BDO waste liquid rich in light components, while the bottom yields a BDO solution with a purity of 99.5 wt%. The light component removal tower has a packing height of 30 theoretical plates, an operating pressure of 5.1 kPa, a reflux ratio of 31, a top temperature of 140°C, and a bottom temperature of 158°C.

[0081] The bottom product from the light component removal tower enters the heavy component removal tower for further separation. A small amount of BDO waste liquid containing light components is collected from the top of the tower, while a side stream yields BDO product with a purity of 99.7 wt%. A BDO solution with a high heavy component content is collected from the bottom of the tower. The heavy component removal tower has a packing height of 43 theoretical plates, an operating pressure of 6.2 kPa, a reflux ratio of 5630, a top temperature of 152°C, and a bottom temperature of 169°C.

[0082] The bottom product from the deweighting tower enters the tar tower, and the bottom product from the tar tower enters the scraped film evaporator. The vapor phase from the scraped film evaporator, containing a relatively high amount of BDO, enters the deweighting tower, while the liquid phase from the scraped film evaporator consists of heavy components with lower BDO content and salt impurities. The scraped film evaporator operates at a pressure of 13 kPa and a temperature of 170 °C.

[0083] Comparative Example 2

[0084] like Figure 3 As shown, the system for the distillation purification of 1,4-butanediol includes a tar tower, a light oil removal tower, a heavy oil removal tower, and a scraped film evaporator.

[0085] BDO crude feedstock underwent initial separation in the tar tower. The composition of the BDO crude feedstock was: 94 wt% 1,4-butanediol, 0.2 wt% TBA, 5.3 wt% light components, and 0.5 wt% remaining heavy components. The top of the tower yielded water, TBA, other light components, and most of the BDO; the bottom of the tower yielded BDO and other heavy components. The tar tower packing height was 23 theoretical plates, the operating pressure was 5 kPa, the reflux ratio was 0.16, the top temperature was 144℃, and the bottom temperature was 168℃. The heavy component content in the top sample was less than 0.3 wt%, and the light component content in the bottom sample was less than 0.1 wt%.

[0086] The tar from the top of the tar tower, after condensation and partial reflux, enters the light component removal tower for separation. The top of the tower yields BDO waste liquid rich in light components, while the bottom yields a BDO solution with a purity of 99.5 wt%. The light component removal tower has a packing height of 30 theoretical plates, an operating pressure of 5.1 kPa, a reflux ratio of 31, a top temperature of 140°C, and a bottom temperature of 158°C.

[0087] The bottom product from the light component removal tower enters the heavy component removal tower for further separation. A small amount of BDO waste liquid containing light components is collected from the top of the tower, while a side stream yields BDO product with a purity of 99.7 wt%. A BDO solution with a high heavy component content is collected from the bottom of the tower. The heavy component removal tower has a packing height of 43 theoretical plates, an operating pressure of 6.2 kPa, a reflux ratio of 5630, a top temperature of 152°C, and a bottom temperature of 169°C.

[0088] The bottom product from the deweighting tower enters the tar tower, and the bottom product from the tar tower enters the scraped film evaporator. The vapor phase from the scraped film evaporator, containing a relatively high amount of BDO, enters the deweighting tower, while the liquid phase from the scraped film evaporator consists of heavy components with lower BDO content and salt impurities. The scraped film evaporator operates at a pressure of 13 kPa and a temperature of 170 °C.

[0089] Comparative Example 3

[0090] like Figure 4 As shown, the system for the distillation purification of 1,4-butanediol includes a light-removal column, a heavy-removal column, and a scraped-film evaporator.

[0091] BDO crude feedstock underwent initial separation in the light component removal tower. The composition of the BDO crude feedstock was: 94 wt% 1,4-butanediol, 0.2 wt% TBA, 5.3 wt% light components, and 0.5 wt% remaining heavy components. The top product contained water, TBA, other light components, and a small amount of BDO; the bottom product contained BDO and other heavy components. The light component removal tower had a packing height of 30 theoretical plates, an operating pressure of 5.1 kPa, a reflux ratio of 35, a top temperature of 135°C, and a bottom temperature of 158°C. The heavy component content in the top sample was less than 0.3 wt%, and the light component content in the bottom sample was less than 0.1 wt%.

[0092] The bottom product from the light component removal tower enters the heavy component removal tower for further separation. A small amount of BDO waste liquid containing light components is collected from the top of the tower, while a side stream yields BDO product with a purity of 99.7 wt%. A BDO solution with a high heavy component content is collected from the bottom of the tower. The heavy component removal tower has a packing height of 43 theoretical plates, an operating pressure of 6.2 kPa, a reflux ratio of 5630, a top temperature of 152°C, and a bottom temperature of 169°C.

[0093] The bottom product from the deweighting tower enters the scraped-film evaporator for separation. The vapor phase from the scraped-film evaporator, containing a higher concentration of BDO, returns to the bottom of the deweighting tower, while the liquid phase from the scraped-film evaporator consists of heavier components with lower BDO content and salt impurities. The scraped-film evaporator operates at a pressure of 13 kPa and a temperature of 170 °C.

[0094] Comparative Example 4

[0095] like Figure 5 As shown, the system for the distillation purification of 1,4-butanediol includes a tar tower, a light oil removal tower, a heavy oil removal tower, and a scraped film evaporator.

[0096] BDO crude feedstock underwent initial separation in the light component removal tower. The composition of the BDO crude feedstock was: 94 wt% 1,4-butanediol, 0.2 wt% TBA, 5.3 wt% light components, and 0.5 wt% remaining heavy components. The top product contained water, TBA, other light components, and a small amount of BDO; the bottom product contained BDO and other heavy components. The light component removal tower had a packing height of 30 theoretical plates, an operating pressure of 5.1 kPa, a reflux ratio of 35, a top temperature of 135°C, and a bottom temperature of 158°C. The heavy component content in the top sample was less than 0.3 wt%, and the light component content in the bottom sample was less than 0.1 wt%.

[0097] The bottom of the light component removal tower is collected and fed into the heavy component removal tower for further separation. A small amount of BDO waste liquid containing light components is collected from the top of the tower, a side stream of BDO with a slightly higher content of heavy components is collected, and a BDO solution with a high content of heavy components is collected from the bottom of the tower. The heavy component removal tower has a packing height of 43 theoretical plates, an operating pressure of 6.2 kPa, a reflux ratio of 5630, a top temperature of 152°C, and a bottom temperature of 169°C.

[0098] The BDO product collected from the side of the deweighting tower is fed into the tar tower for separation and purification. The top of the tar tower yields a BDO product with a purity of 99.7 wt%, while the bottom of the tar tower yields a BDO solution with a slightly higher heavy component, which is then fed into the deweighting tower. The tar tower has a packing height of 23 theoretical plates, an operating pressure of 5 kPa, a reflux ratio of 500, a top temperature of 162℃, and a bottom temperature of 168℃.

[0099] The liquid phase collected from the bottom of the deweighting tower enters the scraped film evaporator for separation. The vapor phase from the scraped film evaporator, containing a higher concentration of BDO, returns to the bottom of the deweighting tower. The liquid phase collected from the scraped film evaporator consists of heavy components with lower BDO content and salt impurities. The scraped film evaporator operates at a pressure of 13 kPa and a temperature of 170 °C.

[0100] Comparative Example 5

[0101] like Figure 6 As shown, the system for the distillation purification of 1,4-butanediol includes a tar tower, a light oil removal tower, a heavy oil removal tower, and a scraped film evaporator.

[0102] BDO crude feedstock underwent initial separation in the light component removal tower. The composition of the BDO crude feedstock was: 94 wt% 1,4-butanediol, 0.2 wt% TBA, 5.3 wt% light components, and 0.5 wt% remaining heavy components. The top product contained water, TBA, other light components, and a small amount of BDO; the bottom product contained BDO and other heavy components. The light component removal tower had a packing height of 30 theoretical plates, an operating pressure of 5.1 kPa, a reflux ratio of 35, a top temperature of 135°C, and a bottom temperature of 158°C. The heavy component content in the top sample was less than 0.3 wt%, and the light component content in the bottom sample was less than 0.1 wt%.

[0103] A portion of the BDO from the bottom of the light component removal tower enters the heavy component removal tower for further separation. A small amount of BDO waste liquid containing light components is collected from the top of the tower, a side stream of 99.7 wt% BDO product is collected, and a BDO solution with a high heavy component content is collected from the bottom. The heavy component removal tower has a packing height of 43 theoretical plates, an operating pressure of 6.2 kPa, a reflux ratio of 5630, a top temperature of 152°C, and a bottom temperature of 169°C.

[0104] Another portion is collected from the bottom of the light component removal tower and enters the tar tower for separation. A small amount of BDO waste liquid containing light components is collected from the top of the tower, a side stream of BDO product with a purity of 99.7 wt% is collected, and the BDO solution with a high content of heavy components is collected from the bottom of the tower and enters the heavy component removal tower. The tar tower packing height is 23 theoretical plates, the operating pressure is 5 kPa, the reflux ratio is 5000, the top temperature is 152℃, and the bottom temperature is 169℃.

[0105] The liquid phase collected from the bottom of the deweighting tower enters the scraped film evaporator for separation. The vapor phase from the scraped film evaporator, containing a higher concentration of BDO, returns to the bottom of the deweighting tower. The liquid phase collected from the scraped film evaporator consists of heavy components with lower BDO content and salt impurities. The scraped film evaporator operates at a pressure of 13 kPa and a temperature of 170 °C.

[0106] Different distillation processes were used in Example 1 and Comparative Examples 1-5 of this invention, and the specific separation effects are shown in Table 1.

[0107] Table 1

[0108]

[0109]

[0110] Referring to Table 1, under the condition of constant product yield and quality, comparing Example 1 with Comparative Examples 1-5, Example 1 reduces the repeated gasification of most heavy components in the light component removal tower, resulting in lower overall process energy consumption and lower operating load on the light component removal tower and tar tower. The differences and shortcomings between Comparative Examples 1-5 and Example 1 are as follows:

[0111] Compared with Comparative Example 1, most of the heavy components in Comparative Example 1 are repeatedly gasified in the light component removal tower, resulting in higher overall process energy consumption, greater operating load on the light component removal tower and tar tower, and the BDO-containing gas phase heavy components in the scraped film evaporator are only enriched once in the tar tower, resulting in higher energy consumption in the tar tower.

[0112] Compared with Example 1, Example 2 shows that most of the heavy components in Example 2 are also repeatedly gasified in the light component removal tower, resulting in higher overall energy consumption and greater operating load for the light component removal tower and tar tower.

[0113] Compared with Comparative Example 1, Comparative Example 3 shows that the dual-tower distillation of light and heavy fractions in Comparative Example 3 requires a higher reflux ratio, and the operating load of each tower is relatively large, reaching flooding conditions and making normal operation impossible.

[0114] Compared with Comparative Example 1, in Comparative Example 4, both light and heavy components were enriched in the de-heavy component tower at the same time, resulting in a larger reflux ratio in the de-heavy component tower, which reached the flooding condition and could not operate normally.

[0115] Compared with Example 1, Comparative Example 5 shows that both the light and heavy removal towers in Comparative Example 5 require high reflux ratios to achieve the product purity requirements, and each tower produces its own product, which cannot guarantee stable product quality.

[0116] Therefore, in summary, Example 1 can achieve low-energy operation, and each distillation column is still within its operating capacity, which has certain economic benefits and feasibility.

[0117] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are within the spirit and scope of the present invention.

Claims

1. A system for rectification purification of 1,4-butanediol, characterized by, The system comprises: a tar column for receiving 1,4-butanediol crude material and rectifying and separating light components and heavy components in the 1,4-butanediol crude material to obtain a first gas phase material containing light components and 1,4-butanediol and a first liquid phase material containing heavy components and 1,4-butanediol; a light component removal column for receiving the first gas phase material from the tar column and rectifying and removing TBA and low-boiling impurities in the 1,4-butanediol to obtain a light component gas phase and a second liquid phase material containing 1,4-butanediol after removal of light components; a heavy component removal column for receiving the first liquid phase material from the tar column and the second liquid phase material from the light component removal column and rectifying and removing high-boiling impurities in the 1,4-butanediol to obtain a light component gas phase, a third liquid phase material, and a refined 1,4-butanediol product; The system further comprises a heat exchanger in communication with the heavy component removal column for receiving the third liquid phase material from the heavy component removal column and separating to obtain a gas phase rich in 1,4-butanediol and a liquid phase containing heavy components and salt impurities. The heat exchanger comprises a feed inlet, a gas phase outlet, and a liquid phase outlet; the liquid phase outlet at the bottom of the heavy component removal column is in communication with the feed inlet of the heat exchanger, the gas phase outlet of the heat exchanger is in communication with the feed inlet of the heavy component removal column, and the liquid phase outlet of the heat exchanger is connected to a heavy component pipeline.

2. The system for rectification and purification of 1,4-butanediol according to claim 1, characterized by the fact that, The tar column, the light component removal column, and the heavy component removal column each comprise a feed inlet, a gas phase outlet at the top, and a liquid phase outlet at the bottom, and further comprise a gas phase condensation reflux device at the top; the gas phase outlet at the top is in communication with the gas phase condensation reflux device at the top.

3. The system for rectifying and purifying 1,4-butanediol according to claim 2, wherein The feed inlet of the tar column is in communication with a 1,4-butanediol crude material pipeline, the liquid phase outlet at the bottom of the tar column is in communication with the feed inlet of the heavy component removal column, and the gas phase condensation reflux device at the top of the tar column is in communication with the feed inlet of the light component removal column.

4. The system for rectifying and purifying 1,4-butanediol according to claim 2, wherein The liquid phase outlet at the bottom of the light component removal column is in communication with the feed inlet of the heavy component removal column, and the gas phase condensation reflux device at the top of the light component removal column is connected to a light component pipeline.

5. The system for rectifying and purifying 1,4-butanediol according to claim 2, wherein The gas phase condensation reflux device at the top comprises a condenser, a reflux tank, and a reflux pump; the gas phase outlet at the top is in communication with the condenser and the reflux tank, and then flows back to the tar column, the light component removal column, or the heavy component removal column through the reflux pump.

6. A method for the rectification purification of 1,4-butanediol, using the system according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: 1,4-butanediol crude material is fed into the tar column for rectification and separation to obtain a first gas phase material containing light components and 1,4-butanediol and a first liquid phase material containing heavy components and 1,4-butanediol; The first gas phase material from the tar column is fed into the light component removal column for rectification and removal of TBA and low-boiling impurities in the 1,4-butanediol of the first gas phase material to obtain a light component gas phase and a second liquid phase material containing 1,4-butanediol after removal of light components; The first liquid phase material from the tar column and the second liquid phase material from the light component removal column are fed into the heavy component removal column for rectification and removal of high-boiling impurities in the 1,4-butanediol of the first liquid phase material and the second liquid phase material to obtain a light component gas phase, a third liquid phase material, and a refined 1,4-butanediol product; The method further comprises: the third liquid phase material from the heavy component removal column is fed into the heat exchanger for separation to obtain a gas phase rich in 1,4-butanediol and a liquid phase containing heavy components and salt impurities. The heat exchanger obtains the gas phase into the heavy component removal tower again.

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