System and method for rectifying and purifying 1, 4-butanediol

Abstract

The invention discloses a system and a method for rectification and purification of 1, 4-butanediol, and the method comprises the following steps: 1, 4-butanediol coarse material enters a tar tower 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 method comprises the following steps: feeding a first gas-phase material from a tar tower into a light component removal tower, and rectifying to remove TBA and low-boiling-point substance impurities in 1, 4-butanediol of the first gas-phase material so as to obtain a light component gas phase and a second liquid-phase material containing 1, 4-butanediol subjected to light component removal; the first liquid phase material from the tar tower and the second liquid phase material from the light component removal tower enter a heavy component removal tower, and rectification is performed to remove high-boiling residue impurities in 1, 4-butanediol of the first liquid phase material and the second liquid phase material, so that a light component gas phase, a third liquid phase material and a refined 1, 4-butanediol product are obtained. Through simultaneous desalination and heavy component removal, the operation energy consumption can be reduced, and the operation upper limit of each rectifying tower is improved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a system and method for distillation and purification of 1,4-butanediol. Background Art

[0002] In the process of producing 1,4-butanediol (BDO) by the acetylene aldehyde process, butynediol is hydrogenated under the action of a catalyst to generate BDO, while butanol, propanol, methanol, γ-hydroxybutyric acid, butenediol, 2(4-hydroxybutoxy)tetrahydrofuran (TBA), high boiling points and salts are produced as by-products; 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 about 95wt%, and the crude BDO solution is then sent to a BDO refining system for separation and purification to obtain 99.7wt% refined BDO. This process is the main energy consumption in the operation of the BDO device. The traditional distillation process has the problems of high operating load and high energy consumption of each distillation tower. Under high load operation conditions, abnormal operation of the distillation tower with high pressure drop and flooding is prone to occur.

[0003] Patent CN114669073A discloses a 1,4-butanediol multi-effect distillation device system and a multi-effect distillation process. The device system includes a dehydration, desalination, residue removal, product purification and heat optimization system, and realizes low-carbon and low-energy optimization of the distillation process through multi-effect distillation and optimization of the heat in the system. This system has high heat integration and low unit energy consumption, but the double-effect distillation requires a high-pressure distillation tower, which has a high operating temperature and is prone to cause BDO polymerization to produce impurities, resulting in unqualified product quality.

[0004] Patent CN1114853573A provides a system and method for separating and purifying 1,4-butanediol. The relative volatility of 1,4-butanediol and 2-(4-hydroxybutoxy)tetrahydrofuran is increased by a composite extractant to obtain BDO with a purity of more than 99.99%, reduce BDO loss, have high separation efficiency, and high product purity. However, the introduction of a new extractant requires additional equipment and may cause extractant impurities to enter the BDO product.

[0005] Patent CN107778141A discloses a method for purifying 1,4-butanediol, which comprises: contacting crude 1,4-butanediol containing aldehyde compounds and / or acetal compounds as impurities with a silver-loaded resin catalyst under hydrogen conditions to obtain purified 1,4-butanediol with a chromaticity less than 10 APHA. The method of the present invention can purify crude 1,4-butanediol containing aldehyde compounds and / or acetal compounds as impurities and reduce the chromaticity of crude 1,4-butanediol, but this method is only for purification of aldehyde-containing systems and cannot achieve separation and purification of impurities in the BDO system itself.

[0006] At present, most BDO refining processes adopt the process of removing salt first and then removing impurities, which leads to multiple vaporization of heavy component impurities in the distillation system, increased energy consumption, and excessive operating load of each tower, making it impossible to achieve stable operation under high load conditions. Summary of the invention

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

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

[0009] A tar tower is used to receive the 1,4-butanediol crude material and perform distillation separation on the light component and the heavy component therein to obtain a first gas phase material containing the light component and 1,4-butanediol and a first liquid phase material containing the heavy component and 1,4-butanediol;

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

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

[0012] Furthermore, the system of the present invention also includes a heat exchanger connected to the deweighting tower, which is used to receive the third liquid phase material from the deweighting tower and separate 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, light-removal tower and heavy-removal tower all include a feed inlet, a top gas phase outlet and a bottom liquid phase outlet, and preferably, also include a top gas phase condensation reflux device, and the top gas phase outlet is connected to the top gas phase condensation reflux device.

[0014] Furthermore, the feed port of the tar tower is connected to the incoming pipeline carrying 1,4-butanediol crude material, the bottom liquid phase outlet of the tar tower is connected to the feed port of the de-weighting tower, and the top gas phase condensation reflux device of the tar tower is connected to the feed port of the de-weighting tower.

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

[0016] Furthermore, the heat exchanger includes a feed port, a gas phase outlet and a liquid phase outlet; the liquid phase outlet at the bottom of the deweighting tower is connected to the feed port of the evaporator, the gas phase outlet of the heat exchanger is connected to the feed port of the deweighting tower, and the liquid phase outlet of the heat exchanger is connected to the heavy component pipeline.

[0017] Furthermore, a deweighting tower kettle pump is provided on the recombinant pipeline.

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

[0019] Furthermore, the tower top gas phase condensation reflux device includes a condenser, a reflux tank and a reflux pump; the tower top gas phase outlet is connected to the condenser and the reflux tank, and then refluxes to the tar tower, the light removal tower or the heavy removal tower through the reflux pump.

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

[0021] The crude 1,4-butanediol material enters a tar tower and is distilled 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;

[0022] The first gas phase material from the tar tower enters the light-removing tower, and is distilled to remove TBA and low-boiling impurities in 1,4-butanediol of the first gas phase material, thereby obtaining a light component gas phase and a second liquid phase material containing 1,4-butanediol after light removal;

[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 in 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.

[0024] Furthermore, the method of the present invention further comprises: the third liquid phase material from the deweighting tower enters a 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 by the heat exchanger enters into a deweighting tower.

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

[0027] The tar tower of the present invention is used to perform preliminary separation of light and heavy components of crude 1,4-butanediol (BDO). The first gaseous material containing light components and a small amount of BDO obtained by distillation separation enters the light-removing tower, and the first liquid-phase material containing heavy components and most of BDO enters the de-weighting tower; the first gaseous material from the tar tower enters the light-removing tower, and is distilled to remove TBA and low-boiling impurities in the 1,4-butanediol of the first gaseous material to obtain a light component gas phase and a second liquid-phase material containing 1,4-butanediol after light removal; the first liquid-phase material from the tar tower and the second liquid-phase material from the light-removing tower enter the de-weighting tower, and are distilled to remove high-boiling impurities in 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 above process of the present invention has the advantages over the purification process of the prior art in that:

[0028] (1) Through the present invention, the tar tower preliminarily enriches the heavy components and salts in the tower bottom, reducing the multiple vaporization of the heavy component impurities and saving energy consumption.

[0029] (2) The present invention can reduce the operating load of the lightness removal tower, facilitate stable operation under high load conditions, and improve the operating margin of the lightness removal tower.

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

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

[0032] Therefore, the present invention combines the impurity composition of the BDO system and adopts a three-tower distillation process design of a tar tower, a light removal tower and a heavy removal tower to effectively increase the processing capacity of the distillation tower and reduce the energy consumption of the system. Using the method of the present invention, under the condition of BDO purity of 99.7wt%, the energy consumption is 2800KW lower than that of the traditional process. The system of the present invention can be widely used in the BDO refining process, can save energy consumption without increasing equipment investment, and has obvious economic benefits.

[0033] Other features and advantages of the present invention will be described in detail through the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

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

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

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

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

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

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

[0041] Marking instructions: tar tower T1, light removal tower T2, heavy removal tower T3, condensers E1, E2, E3, wiped film evaporator E4. DETAILED DESCRIPTION

[0042] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0043] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0044] Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

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

[0046] A tar tower is used to receive the 1,4-butanediol crude material and perform distillation separation on the light component and the heavy component therein to obtain a first gas phase material containing the light component and 1,4-butanediol and a first liquid phase material containing the heavy component and 1,4-butanediol;

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

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

[0049] In the present invention, the crude 1,4-butanediol material is a crude material containing 1,4-butanediol after hydrogenation and dehydration of 1,4-butynediol. For the convenience of description, it is referred to as BDO crude material herein. The crude material is separated by a tar tower, and the tar tower is connected to a light removal tower and a heavy removal tower, respectively. In some examples, after the BDO crude material is initially separated in the tar tower, water, TBA, other light components and a small amount of BDO are produced at the top of the tower, that is, the liquid phase after the first gas phase material is condensed; BDO ​​and heavy components are produced at the bottom of the tower, that is, the first liquid phase material.

[0050] In the present invention, the light-removing tower receives the liquid phase after the first gas phase material is condensed and separates it. In some examples, the bottom of the light-removing tower is connected to the heavy-removing tower. A light component mixture containing BDO, TBA and water, i.e., the liquid phase after the light component gas phase is condensed, is produced from the top of the tower; a BDO solution containing TBA and heavy component impurities with a high BDO purity (99.5wt%), i.e., the second liquid phase material, is produced from the bottom of the tower to recover the BDO after light-removal.

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

[0052] The system of the present invention also includes a heat exchanger connected to the deweighting tower, which is used to receive the third liquid phase material from the deweighting tower and separate 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 wiped film evaporator, which receives the third liquid phase material from the deweighting tower), and after separation, the gas phase is produced as BDO rich in heavy components; the liquid phase is produced as heavy components and salt impurities with low BDO content.

[0053] It is understood that the tar tower, light-removal tower and heavy-removal tower all include a feed inlet, a tower top gas phase outlet and a tower bottom liquid phase outlet, and preferably, also have a tower top gas phase condensation reflux device, such as Figure 1 In the device shown in E1, E2 or E3, the top gas phase outlet is connected to the top gas phase condensation reflux device, and the gas phase enters the condenser and is partially extracted and partially refluxed.

[0054] In some examples, the deweighting column further includes a side outlet for obtaining a refined 1,4-butanediol product.

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

[0056] Preferably, the reflux tank includes a non-condenser gas outlet.

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

[0058] It is understandable that the system of the present invention also includes some pipelines for containing and transmitting various components, illustratively including incoming material pipelines, light component pipelines, heavy component pipelines, BDO product pipelines, etc.

[0059] In some examples, the feed port of the tar tower is connected to the incoming pipeline carrying 1,4-butanediol crude material, the bottom liquid phase outlet of the tar tower is connected to the feed port of the de-weighting tower, and the top gas phase condensation reflux device of the tar tower is connected to the feed port of the de-weighting tower.

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

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

[0062] It can be understood that the heat exchanger includes a feed inlet, a gas phase outlet and a liquid phase outlet; the liquid phase outlet at the bottom of the deweighting 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 deweighting tower, and the liquid phase outlet of the heat exchanger is connected to the heavy component pipeline.

[0063] Preferably, a deweighting tower kettle pump is provided on the recombinant fraction pipeline.

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

[0065] The crude 1,4-butanediol material enters a tar tower and is distilled 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;

[0066] The first gas phase material from the tar tower enters the light-removing tower, and is distilled to remove TBA and low-boiling impurities in 1,4-butanediol of the first gas phase material, thereby obtaining a light component gas phase and a second liquid phase material containing 1,4-butanediol after light removal;

[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 in 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.

[0068] Furthermore, the method further comprises the following steps: the third liquid phase material of the deweighting tower enters a heat exchanger for separation to obtain a gas phase rich in 1,4-butanediol and a liquid phase containing heavy components and salt impurities.

[0069] Furthermore, the gas phase obtained by the heat exchanger enters the deweighting tower again, and the liquid phase obtained enters the heavy component pipeline.

[0070] The present invention is further described below in conjunction with embodiments:

[0071] Example 1

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

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

[0074] The top of the tar tower is condensed and partially refluxed before entering the light-removal tower for separation. The top of the light-removal tower produces BDO waste liquid rich in light components, and the bottom of the tower produces a solution with a BDO purity of 99.5wt%. The packing height of the light-removal tower is 30 theoretical plates, the operating pressure is 5.1kpa, the reflux ratio is 21.7, the top temperature is 142℃, and the bottom temperature is 160℃.

[0075] The bottom of the tar tower and the bottom of the light removal tower are separated in the de-heavy tower. A small amount of BDO waste liquid containing light components is extracted from the top of the de-heavy tower, and a BDO product with a purity of 99.7wt% is extracted from the side line. The BDO solution with a high content of heavy components is extracted from the bottom of the de-heavy tower. The packing height of the de-heavy tower is 43 theoretical plates, the operating pressure is 6.2kpa, the reflux ratio is 5630, the top temperature is 152℃, and the bottom temperature is 169℃.

[0076] The bottom of the de-weighting tower is taken out and separated in the scraped film evaporator. The gas phase outlet of the scraped film evaporator with more BDO enters the bottom of the de-weighting tower, and the liquid phase of the scraped film evaporator is heavy components and salt impurities with low BDO content. The operating pressure of the scraped film evaporator is 13kpa and the temperature is 170℃.

[0077] Comparative Example 1

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

[0079] The BDO crude material is initially separated in the tar tower, and the BDO crude material composition is: 94wt% 1,4-butanediol, 0.2wt% TBA, 5.3wt% light components, and 0.5wt% other heavy components; water, TBA, other light components and most of BDO are produced at the top of the tower; BDO ​​and other heavy components are produced at the bottom of the tower. The packing height of the tar tower is 23 theoretical plates, the operating pressure is 5kpa, the reflux ratio is 0.16, the top temperature is 144℃, the bottom temperature is 168℃, the heavy component content in the top sample is less than 0.3wt%, and the light component content in the bottom sample is less than 0.1wt%.

[0080] The top of the tar tower is condensed and partially refluxed before entering the light-removal tower for separation. BDO waste liquid rich in light components is extracted from the top of the tower, and a solution with a BDO purity of 99.5wt% is extracted from the bottom of the tower. The packing height of the light-removal tower is 30 theoretical plates, the operating pressure is 5.1kpa, the reflux ratio is 31, the top temperature is 140℃, and the bottom temperature is 158℃.

[0081] The bottom of the light removal tower is taken out and sent to the heavy removal tower for separation. A small amount of BDO waste liquid containing light components is taken out from the top of the tower, and a BDO product with a purity of 99.7wt% is taken out from the side line. The BDO solution with a high content of heavy components is taken out from the bottom of the tower. The packing height of the heavy removal tower is 43 theoretical plates, the operating pressure is 6.2kpa, the reflux ratio is 5630, the top temperature is 152℃, and the bottom temperature is 169℃.

[0082] The bottom of the de-weighting tower is taken out and enters the tar tower, and the bottom of the tar tower is taken out and enters the scraped film evaporator. The gas phase outlet of the scraped film evaporator containing more BDO enters the de-weighting tower, and the liquid phase of the scraped film evaporator is the heavy components and salt impurities with low BDO content. The operating pressure of the scraped film evaporator is 13kpa and the temperature is 170℃.

[0083] Comparative Example 2

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

[0085] The BDO crude material is initially separated in the tar tower, and the BDO crude material composition is: 94wt% 1,4-butanediol, 0.2wt% TBA, 5.3wt% light components, and 0.5wt% other heavy components; water, TBA, other light components and most of BDO are produced at the top of the tower; BDO ​​and other heavy components are produced at the bottom of the tower. The packing height of the tar tower is 23 theoretical plates, the operating pressure is 5kpa, the reflux ratio is 0.16, the top temperature is 144℃, the bottom temperature is 168℃, the heavy component content in the top sample is less than 0.3wt%, and the light component content in the bottom sample is less than 0.1wt%.

[0086] The top of the tar tower is condensed and partially refluxed before entering the light-removal tower for separation. BDO waste liquid rich in light components is extracted from the top of the tower, and a solution with a BDO purity of 99.5wt% is extracted from the bottom of the tower. The packing height of the light-removal tower is 30 theoretical plates, the operating pressure is 5.1kpa, the reflux ratio is 31, the top temperature is 140℃, and the bottom temperature is 158℃.

[0087] The bottom of the light removal tower is taken out and sent to the heavy removal tower for separation. A small amount of BDO waste liquid containing light components is taken out from the top of the tower, and a BDO product with a purity of 99.7wt% is taken out from the side line. The BDO solution with a high content of heavy components is taken out from the bottom of the tower. The packing height of the heavy removal tower is 43 theoretical plates, the operating pressure is 6.2kpa, the reflux ratio is 5630, the top temperature is 152℃, and the bottom temperature is 169℃.

[0088] The bottom of the de-weighting tower is taken out and enters the tar tower, and the bottom of the tar tower is taken out and enters the scraped film evaporator. The gas phase outlet of the scraped film evaporator containing more BDO enters the de-weighting tower, and the liquid phase of the scraped film evaporator is the heavy components and salt impurities with low BDO content. The operating pressure of the scraped film evaporator is 13kpa and the temperature is 170℃.

[0089] Comparative Example 3

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

[0091] The BDO crude material is initially separated in the light-removing tower. The BDO crude material composition is: 94wt% 1,4-butanediol, 0.2wt% TBA, 5.3wt% light components, and 0.5wt% other heavy components. Water, TBA, other light components and a small amount of BDO are produced at the top of the tower. BDO and other heavy components are produced at the bottom of the tower. The packing height of the light-removing tower is 30 theoretical plates, the operating pressure is 5.1kpa, the reflux ratio is 35, the top temperature is 135℃, the bottom temperature is 158℃, the heavy component content in the top sample is less than 0.3wt%, and the light component content in the bottom sample is less than 0.1wt%.

[0092] The bottom of the light removal tower is taken out and sent to the heavy removal tower for separation. A small amount of BDO waste liquid containing light components is taken out from the top of the tower, and a BDO product with a purity of 99.7wt% is taken out from the side line. The BDO solution with a high content of heavy components is taken out from the bottom of the tower. The packing height of the heavy removal tower is 43 theoretical plates, the operating pressure is 6.2kpa, the reflux ratio is 5630, the top temperature is 152℃, and the bottom temperature is 169℃.

[0093] The bottom of the de-weighting tower is taken out and enters the scraped film evaporator for separation. The gas phase outlet of the scraped film evaporator containing more BDO enters the bottom of the de-weighting tower, and the liquid phase of the scraped film evaporator is heavy components and salt impurities with low BDO content. The operating pressure of the scraped film evaporator is 13kpa and the temperature is 170℃.

[0094] Comparative Example 4

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

[0096] The BDO crude material is initially separated in the light-removing tower. The BDO crude material composition is: 94wt% 1,4-butanediol, 0.2wt% TBA, 5.3wt% light components, and 0.5wt% other heavy components. Water, TBA, other light components and a small amount of BDO are produced at the top of the tower. BDO and other heavy components are produced at the bottom of the tower. The packing height of the light-removing tower is 30 theoretical plates, the operating pressure is 5.1kpa, the reflux ratio is 35, the top temperature is 135℃, the bottom temperature is 158℃, the heavy component content in the top sample is less than 0.3wt%, and the light component content in the bottom sample is less than 0.1wt%.

[0097] The bottom of the light removal tower is taken out and sent to the heavy removal tower for separation. A small amount of BDO waste liquid containing light components is taken out from the top of the tower, BDO with a slightly higher content of heavy components is taken out from the side line, and BDO solution with a higher content of heavy components is taken out from the bottom of the tower. The packing height of the heavy removal tower is 43 theoretical plates, the operating pressure is 6.2kpa, the reflux ratio is 5630, the top temperature is 152℃, and the bottom temperature is 169℃.

[0098] The side of the de-weighting tower is taken into the tar tower for separation and purification. The BDO product with a purity of 99.7wt% is taken from the top of the tower, and the BDO solution with a slightly higher heavy component is taken from the bottom of the tower and enters the de-weighting tower. The packing height of the tar tower is 23 theoretical plates, the operating pressure is 5kpa, the reflux ratio is 500, the top temperature is 162℃, and the bottom temperature is 168℃.

[0099] The bottom of the de-weighting tower is extracted and sent to the scraped film evaporator for separation. The gas phase outlet of the scraped film evaporator containing more BDO enters the bottom of the de-weighting tower. The liquid phase extracted from the scraped film evaporator is heavy components and salt impurities with low BDO content. The operating pressure of the scraped film evaporator is 13kpa and the temperature is 170℃.

[0100] Comparative Example 5

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

[0102] The BDO crude material is initially separated in the light-removing tower. The BDO crude material composition is: 94wt% 1,4-butanediol, 0.2wt% TBA, 5.3wt% light components, and 0.5wt% other heavy components. Water, TBA, other light components and a small amount of BDO are produced at the top of the tower. BDO and other heavy components are produced at the bottom of the tower. The packing height of the light-removing tower is 30 theoretical plates, the operating pressure is 5.1kpa, the reflux ratio is 35, the top temperature is 135℃, the bottom temperature is 158℃, the heavy component content in the top sample is less than 0.3wt%, and the light component content in the bottom sample is less than 0.1wt%.

[0103] A portion of the light-removing tower bottom is taken out and sent to the heavy-removing tower for separation. A small amount of BDO waste liquid containing light components is taken out from the top of the tower, a BDO product with a purity of 99.7wt% is taken out from the side line, and a BDO solution with a high content of heavy components is taken out from the bottom of the tower. The packing height of the heavy-removing tower is 43 theoretical plates, the operating pressure is 6.2kpa, the reflux ratio is 5630, the top temperature is 152℃, and the bottom temperature is 169℃.

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

[0105] The bottom of the de-weighting tower is extracted and sent to the scraped film evaporator for separation. The gas phase outlet of the scraped film evaporator containing more BDO enters the bottom of the de-weighting tower. The liquid phase extracted from the scraped film evaporator is heavy components and salt impurities with low BDO content. The operating pressure of the scraped film evaporator is 13kpa and the temperature is 170℃.

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

[0107] Table 1

[0108]

[0109]

[0110] Combined with Table 1, under certain conditions of product output and quality, compared with Example 1 and Comparative Examples 1-5, Example 1 reduces the repeated gasification of most heavy components in the light-removing tower, the overall energy consumption of the process is lower, and the operating load of the light-removing tower and the tar tower is smaller; the differences and defects of Comparative Examples 1-5 and Example 1 are as follows:

[0111] Comparing Example 1 with Comparative Example 1, most of the heavy components in Comparative Example 1 are repeatedly gasified in the light removal tower, the overall energy consumption of the process is higher, the light removal tower and the tar tower have a greater operating load, and the gas phase heavy components containing BDO in the wiped film evaporator are only enriched once in the tar tower, resulting in higher energy consumption in the tar tower;

[0112] Comparing Example 1 with Comparative Example 2, most of the heavy components in Comparative Example 2 are also repeatedly gasified in the light-removing tower, the overall energy consumption of the process is higher, and the operating load of the light-removing tower and the tar tower is greater;

[0113] Comparing Example 1 with Comparative Example 3, the double-tower distillation light and heavy component towers of Comparative Example 3 both need to increase the reflux ratio, and the operating load of each tower is large, reaching the flooding condition, and normal operation cannot be achieved;

[0114] Comparing Example 1 with Comparative Example 4, in Comparative Example 4, light and heavy components are simultaneously enriched in the de-weighting tower, resulting in a larger reflux ratio of the de-weighting tower, reaching the flooding condition, and being unable to operate normally;

[0115] Comparing Example 1 with Comparative Example 5, both the light removal tower and the heavy removal tower of Comparative Example 5 require a high reflux ratio to achieve the product purity requirement, and the two towers produce their own products, which cannot ensure stable product quality.

[0116] Therefore, comprehensive comparison shows that Example 1 can achieve low energy consumption operation, and each distillation tower is still within the operating capacity, which has certain economic benefits and feasibility.

[0117] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are within the spirit scope of the present invention.

Claims

1. A system for distillation and purification of 1,4-butanediol, characterized in that: include: A tar tower is used to receive the 1,4-butanediol crude material and perform distillation separation on the light component and the heavy component therein to obtain a first gas phase material containing the light component and 1,4-butanediol and a first liquid phase material containing the heavy component and 1,4-butanediol; The light-removal tower is used to receive the first gaseous phase material from the tar tower and distill and remove TBA and low-boiling impurities in the 1,4-butanediol therein to obtain a light component gas phase and a second liquid phase material containing the 1,4-butanediol after light removal; The de-heavy tower is used to receive the first liquid phase material from the tar tower and the second liquid phase material from the light tower and to distill and remove high-boiling impurities in the 1,4-butanediol therein to obtain a light component gas phase, a third liquid phase material and a refined 1,4-butanediol product.

2. The system for distillation and purification of 1,4-butanediol according to claim 1, characterized in that: The system further comprises a heat exchanger communicated with the de-weighting tower, for receiving the third liquid phase material from the de-weighting tower and separating the third liquid phase material into a gas phase rich in 1,4-butanediol and a liquid phase containing heavy components and salt impurities.

3. The system for distillation and purification of 1,4-butanediol according to claim 1, characterized in that: The tar tower, light-removal tower and heavy-removal tower all include a feed inlet, a tower top gas phase outlet and a tower bottom liquid phase outlet, and preferably, also include a tower top gas phase condensation reflux device, and the tower top gas phase outlet is connected to the tower top gas phase condensation reflux device.

4. The system for distillation and purification of 1,4-butanediol according to claim 3, characterized in that: The feed port of the tar tower is connected to the feed pipeline carrying 1,4-butanediol crude material, the bottom liquid phase outlet of the tar tower is connected to the feed port of the de-weighting tower, and the top gas phase condensation reflux device of the tar tower is connected to the feed port of the de-weighting tower.

5. The system for distillation and purification of 1,4-butanediol according to claim 3, characterized in that: The bottom liquid phase outlet of the light-removing tower is communicated with the feed inlet of the heavy-removing tower, and the top gas-phase condensing reflux device of the light-removing tower is connected to the light component pipeline.

6. The system for distillation and purification of 1,4-butanediol according to claim 3, characterized in that: The heat exchanger includes a feed port, a gas phase outlet and a liquid phase outlet; the liquid phase outlet at the bottom of the deweighting tower is connected to the feed port of the heat exchanger, the gas phase outlet of the heat exchanger is connected to the feed port of the deweighting tower, and the liquid phase outlet of the heat exchanger is connected to the heavy component pipeline.

7. The system for distillation and purification of 1,4-butanediol according to claim 1, characterized in that: The tower top gas phase condensation reflux device comprises a condenser, a reflux tank and a reflux pump; the tower top gas phase outlet is connected with the condenser and the reflux tank, and then refluxes to the tar tower, the light removal tower or the heavy removal tower through the reflux pump.

8. A method for the rectification and purification of 1,4-butanediol, characterized in that: The steps include: The crude 1,4-butanediol material enters a tar tower and is distilled and separated 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 tower enters the light-removing tower, and is distilled to remove TBA and low-boiling impurities in 1,4-butanediol of the first gas phase material, thereby obtaining a light component gas phase and a second liquid phase material containing 1,4-butanediol after light removal; 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 in 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.

9. The method for rectification and purification of 1,4-butanediol according to claim 8, characterized in that: The method further comprises: the third liquid phase material from the deweighting tower enters a heat exchanger for separation to obtain a gas phase rich in 1,4-butanediol and a liquid phase containing heavy components and salt impurities.

10. The method for purifying 1,4-butanediol by distillation according to claim 9, characterized in that: The gas phase obtained by the heat exchanger enters the deweighting tower again.

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