Method and device for on-line scale prevention of 1, 4-butylene glycol vacuum system

Abstract

The invention provides an online scale prevention method and device for a 1, 4-butenediol vacuum system, and the method comprises the following steps: inputting a 1, 4-butenediol crude product solution into a decolorizing tower filled with an adsorbent for decolorizing treatment, inputting the 1, 4-butenediol crude product solution into a desolventizing tower for removing a solvent, and extracting first tail gas; inputting into a light component removal tower to remove light components and extracting second tail gas; a high-purity 1, 4-butylene glycol product is extracted from the top of the product tower, and third tail gas is extracted; inputting the first tail gas, the second tail gas and the third tail gas into an absorption tower to contact with a lean absorbent in the absorption tower, and inputting tower top tail gas of the absorption tower into a vacuum system; a rich absorbent extracted from a tower kettle of the absorption tower is input into an absorbent regeneration tower, and a lean solvent obtained after regeneration is circulated back to the absorption tower. According to the refining method disclosed by the invention, a 1, 4-butylene glycol product with high purity and low chroma can be obtained, abnormal conditions such as blockage of a vacuum pump and a pipeline are avoided after continuous operation for 200h, and stable and continuous operation is promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical synthesis, in particular to a method and device for online scale prevention of a 1,4-butene diol vacuum system. BACKGROUND

[0002] 1,4-butene diol (abbreviated as BED) is also called 2-butene-1,4-diol, which has a wide application in the chemical industry. It is a monomer for synthesizing polyesters, polyethers and other polymers, and is also a crosslinking agent or modifier for some coatings, high polymer materials, textiles and the like. It can also be used to synthesize fine chemicals such as vitamin B6, endosulfan (herbicide), 2,5-dihydrofuran (drug intermediate). The preparation methods of butene diol mainly include 1,4-butynediol method, butadiene acetoxylation method, and 1,4-dichloro-2-butene method according to raw materials.

[0003] 1,4-butynediol semi-hydrogenation to prepare 1,4-butene diol has the advantages of easy availability of raw materials and low production cost, and is the most commonly used method for producing 1,4-butene diol. The crude product solution of 1,4-butene diol prepared by this method is usually yellow, and needs to be decolorized. Otherwise, the pigment will enter the 1,4-butene diol product in the subsequent rectification process, reducing the product quality and having adverse effects on the process of synthesizing other products using 1,4-butene diol as raw material, such as shortening the service life of the catalyst, increasing the side reactions, etc. In addition, it should be noted that 1,4-butene diol will produce polymers during long-term (150-200h) rectification (refining, purification) process, which will block the vacuum pump or gas inlet pipeline, etc., and the machine must be stopped for maintenance.

[0004] Patent CN118666645A discloses a 1,4-butene diol purification and refining method and system, which adopts a system combined with four towers (water recovery tower, dehydration tower, light component removal tower and product tower) through heat coupling. The heat recovery is realized by sending the water recovery tower kettle material to the light component removal tower and the product tower top condenser respectively through heat coupling. The first tower kettle temperature is adjusted by adjusting the heat load of the water recovery tower to match the third tower and the fourth tower top temperature, realize heat coupling and recover heat, greatly reduce the steam consumption of the water recovery tower kettle, and save energy. The overall process has no waste liquid discharge, and the separated water and light and heavy components can be recycled. However, it does not consider the technical problems of isomerization, condensation and polymerization of 1,4-butene diol at high temperature, which leads to problems such as vacuum pump blockage after long-term operation of the system.

[0005] Patent CN106397129A discloses a kind of 1,4-butynediol hydrogenation continuous production 1,4-butene glycol coproduction 1,4-butanediol system and process, system includes the decolorization reaction system, semi-hydrogenation reaction system, butene glycol rectification system, full hydrogenation reaction system, butanediol rectification system connected in turn.Butynediol raw material tank is connected with decolorization reaction system by butynediol raw material delivery pump, the decolorization reaction system is connected with semi-hydrogenation reaction system by reaction liquid metering pump, the semi-hydrogenation reaction system is connected with butene glycol rectification system by second crude butene glycol metering pump, the butene glycol rectification system is connected with full hydrogenation reaction system by butanediol full hydrogenation metering pump, the full hydrogenation reaction system is connected with butanediol rectification system by crude butanediol metering pump.This technical solution still exists 1,4-butene glycol rectification kettle temperature is too high, the problems such as the polymerization of uncondensed 1,4-butene glycol, the system still can be blocked for a long time vacuum pump. SUMMARY

[0006] In view of the deficiencies in the prior art, the present application discloses a method and device for online scale prevention of a 1,4-butene glycol vacuum system, which can fully recover 1,4-butene glycol in tail gas of a 1,4-butene glycol refining process, thereby effectively preventing the vacuum pump from being blocked.

[0007] To achieve the above technical purposes, in one aspect, the present application provides a method for online scale prevention of a 1,4-butene glycol vacuum system, which comprises the following steps:

[0008] (1) A 1,4-butene glycol crude product solution is input into a decolorization tower filled with adsorbent, and a first material is obtained by decolorization treatment;

[0009] (2) The first material is input into a desolventizing tower to remove solvent, and a second material is collected from the tower kettle of the desolventizing tower; the overhead product of the desolventizing tower is condensed to obtain a liquid-phase solvent, and a first tail gas is collected;

[0010] (3) The second material is input into a light component removal tower, and a third material is collected from the tower kettle of the light component removal tower; the overhead product of the light component removal tower is condensed to obtain a liquid-phase light component material, and a second tail gas is collected;

[0011] (4) The third material is input into a product tower, and the overhead product of the product tower is condensed to output a liquid-phase high-purity 1,4-butene glycol product, and a third tail gas is collected;

[0012] (5) The first tail gas, the second tail gas and the third tail gas are input into an absorption tower to contact with lean absorbent in the absorption tower, and the overhead tail gas of the absorption tower is input into a vacuum system; the rich absorbent collected from the tower kettle of the absorption tower is input into an absorbent regeneration tower, and lean solvent is obtained after regeneration and recycled to the absorption tower.

[0013] In 2024, Rongze et al. found that 4-hydroxybutyraldehyde was generated as a byproduct in the process of generating 1,4-butanediol, and the mechanism of generation may be that 1,4-butanediol undergoes double bond migration and isomerization reaction under the action of the catalyst (Fine Chemicals, 2024, Vol. 41, No. 2). Reaction formula 1 is as follows:

[0014]

[0015] 4-hydroxybutyraldehyde undergoes oxidation, condensation and other reactions to generate red substances; 4-hydroxybutyraldehyde may also dehydrate to generate butenal, and butenal polymerizes to generate dimers, as shown in reaction formula 2:

[0016]

[0017] 4-hydroxybutyraldehyde is also prone to intramolecular cyclization to generate 2-hydroxytetrahydrofuran, which dehydrates under high vacuum to generate 2,3-dihydrofuran, which then undergoes a polymerization reaction, as shown in reaction formula 3:

[0018]

[0019] 1,4-butanediol is prone to dehydration and cyclization to generate 2,5-dihydrofuran under high temperature and high vacuum conditions, and 2,5-dihydrofuran polymerizes to generate a high molecular compound, as shown in reaction formula 4:

[0020]

[0021] 1,4-butanediol also undergoes a free radical reaction during the reaction and rectification process to generate a chain polymer, as shown in reaction formula 5:

[0022]

[0023] During the refining process of the crude 1,4-butanediol solution, these high molecular compounds are separated by a rectification column, removed from the system as still bottoms, and the overhead product is condensed to obtain high-purity 1,4-butanediol in liquid phase, and the condensed tail gas (containing 1,4-butanediol, 4-hydroxybutyraldehyde, 1,4-butanediol, hydrogenation solvent, etc.) is input into a vacuum system. The inventors have found through a large number of experiments that the tail gas input into the vacuum system (including the vacuum pump) may generate high molecular compounds of the above reaction formulas 3, 4 and 5, which accumulate in the pipeline of the vacuum pump in the form of tar or powder, causing the vacuum pump to be blocked.

[0024] The above technical solution uses six functional columns to achieve decolorization, purification and deep treatment of the tail gas of the crude 1,4-butanediol solution, to solve the problem of vacuum pump blockage in the existing 1,4-butanediol refining process:

[0025] (1) The existing 1,4-butynediol preparation process usually obtains 1,4-butenediol after decolorizing the 1,4-butynediol solution and then semi-hydrogenation. However, colored impurities are still produced in the hydrogenation process of 1,4-butynediol, so the color of the reaction solution after hydrogenation is deepened. The above technical solution sets a decoloring tower to adsorb and decolorize the 1,4-butenediol crude product solution, which can remove the colored impurities in 1,4-butynediol and the colored impurities produced in the hydrogenation reaction at the same time, and obtain 1,4-butynediol products with lower colority and higher purity.

[0026] (2) The above technical solution gradually removes the solvent, light component impurities (including 1,4-butanediol) and heavy component impurities (high-boiling substances) in the first material through the desolventizing tower, the light component removal tower and the product tower, to obtain high-purity 1,4-butenediol.

[0027] (3) The above technical solution further absorbs and recovers 1,4-butanediol, 1,4-butenediol and the like in the tail gas generated during the operation of the desolventizing tower, the light component removal tower and the product tower through the solvent absorption tower, so that the polymerization and accumulation of 1,4-butenediol and by-products in the vacuum pump pipeline can be effectively reduced, the probability of pipeline blockage can be reduced, the maintenance frequency can be reduced, and the stable and continuous operation of the 1,4-butenediol refining process can be promoted.

[0028] It should be noted that the lean absorbent in the present application refers to the absorbent that has not performed absorption operation or has completed regeneration, and its absorption capacity is strong after releasing solute; the rich absorbent refers to the absorbent that has completed absorption operation, and its absorption capacity is strong after absorbing a large amount of solute or tending to saturation. The tail gas at the top of the absorption tower refers to the gas phase material obtained after condensation and separation of the material taken from the top of the absorption tower.

[0029] Further, the mass concentration of 1,4-butenediol in the rich absorbent is 10% to 40%, preferably 20% to 30%.

[0030] Further, the rich solvent is regenerated by the absorbent regeneration tower to obtain a recovered stream, and the recovered stream is input into the light component removal tower. The part of the circulating material mainly includes 1,4-butenediol, 1,4-butenediol, which is input into the light component removal tower to improve the refining yield of the target product and improve the economic benefit of the process.

[0031] Further, a defoamer is arranged inside the top of the absorption tower to prevent liquid droplets from being entrained into the tail gas at the top of the absorption tower.

[0032] It should be noted that the specific structure of the adsorption tower in the present application is not limited, and a fixed bed adsorption tower can be selected. Those skilled in the art can select appropriate adsorbents according to the working conditions, and the technical solutions formed thereby are within the protection scope of the present application.

[0033] Further, the absorbent is selected from at least one of hydrocarbon, alcohol, ether, nitrile and the like. Still further, the absorbent includes C9-C 20 at least one of paraffin, high-boiling monohydric alcohol, dihydric alcohol or polyhydric alcohol, aryl ether, di- or aryl nitrile. Still further, the absorbent of the present application preferably has a normal boiling point lower than 205℃ to reduce the production cost. The high-boiling monohydric alcohol herein refers to monohydric alcohol having a normal boiling point higher than 150℃.

[0034] wherein, optionally, the hydrocarbon includes nonane, decane, undecane, dodecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, preferably undecane and dodecane; optionally, the alcohol includes high-boiling monohydric alcohol, dihydric alcohol, polyhydric alcohol, further preferably benzyl alcohol, cyclohexanol, n-octanol, iso-octanol, ethylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, glycerol, still further preferably ethylene glycol; and the ether optionally includes phenetole, diphenyl ether, further preferably phenetole; and the nitrile optionally includes succinonitrile, benzonitrile, further preferably benzonitrile.

[0035] It is noted that depending on the boiling point of the absorbent relative to that of 1,4-butanediol, the absorbent regenerator can be configured to withdraw the lean absorbent from the bottom or the top of the column, for example, when the absorbent has a boiling point not higher than that of 1,4-butanediol, the absorbent is withdrawn from the top of the absorbent regenerator and recovered, and the recovered stream containing 1,4-butanediol is withdrawn from the bottom of the column; when the absorbent has a boiling point higher than that of 1,4-butanediol, the absorbent is withdrawn from the bottom of the absorbent regenerator, and the recovered stream containing 1,4-butanediol is withdrawn from the top of the column.

[0036] Further, the 1,4-butanediol crude product solution has a 1,4-butanediol content of 20wt% to 60wt%, preferably 30wt% to 50wt%. Still further, the 1,4-butanediol crude product solution is prepared by 1,4-diacetylene glycol method or butadiene acetoxylation method. The embodiments of the present application show the refining process of the 1,4-butanediol crude product solution prepared by 1,4-diacetylene glycol method or butadiene acetoxylation method.

[0037] Further, the solvent of the 1,4-butanediol crude product solution includes at least one of water, alcohol, ether, amide. Still further, the solvent of the 1,4-butanediol crude product solution includes at least one of water, C1-C5 alcohol, C3-C8 ether, C3-C5 amide.

[0038] Still further, the alcohol includes at least one of methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, n-pentanol, further preferably methanol and ethanol.

[0039] Further, the ether includes at least one of tetrahydrofuran, 1,4-dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and further preferably tetrahydrofuran or 1,4-dioxane.

[0040] Further, the amide includes at least one of N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, and further preferably N,N-dimethylformamide.

[0041] Further, the adsorbent is a macroporous adsorption resin or activated carbon. Further, the activated carbon has a specific surface area of 600-1200 m 2 / g, and preferably 800-1000 m 2 / g; and a bulk density of 0.4-0.7 g / cm 3 , and preferably 0.5-0.6 g / cm 3 . The activated carbon can be selected according to the color of the reaction, and the larger the specific surface area of the activated carbon, the stronger the decolorizing ability. In an alternative embodiment of the present application, the activated carbon has a specific surface area of 800-1000 m 2 / g. In an alternative embodiment of the present application, the activated carbon has a bulk density of 0.5-0.6 g / cm 3 .

[0042] Further, the decolorizing tower has an operating temperature of 60-90°C, an operating pressure of 0.1-0.3 MPaG, and a space velocity of 0.5-2 h -1 . The operating pressure can be selected according to the mass transfer rate and production efficiency, and increasing the operating pressure can help to improve the production efficiency. In an alternative embodiment of the present application, the decolorizing tower has an operating temperature of 70-80°C. In an alternative embodiment of the present application, the decolorizing tower has an operating pressure of 0.2-0.3 MPaG. In an alternative embodiment of the present application, the decolorizing tower has a space velocity of 1-1.5 h -1 .

[0043] Further, the desolventizing tower has a top temperature of 15-40°C, a bottom temperature of 140-160°C, and an operating pressure of 5-20 kPaA, and preferably 5-10 kPaA. Further, the desolventizing tower has a theoretical plate number of 10-15, and preferably 10-12, and a feed position of the 6th-7th plate.

[0044] Further, the overhead temperature of the light-removing column is 70-90℃, the bottom temperature is 130-140℃, and the operating pressure is 0.2-5 kPaA. In an alternative example of the present application, the operating pressure of the light-removing column is 0.5-2 kPaA. Further, the number of theoretical plates of the light-removing column is 20-35, preferably 20-30; and the feed position is the 15th-17th plate.

[0045] Further, the overhead temperature of the product column is 130-135℃, the bottom temperature is 135-150℃, and the operating pressure is 0.2-5 kPaA. In an alternative example of the present application, the operating pressure of the product column is 0.5-2 kPaA. Further, the number of theoretical plates of the product column is 30-40, preferably 30-35; and the feed position is the 20th-22nd plate.

[0046] Further, the overhead temperature of the absorption column is 0-5℃, the bottom temperature is 25-40℃, and the operating pressure is 0.2-5 kPaA. In an alternative example of the present application, the operating pressure of the absorption column is 0.5-2 kPaA. Further, the number of theoretical plates of the absorption column is 10-15, preferably 10-12; and the feed position is the bottom.

[0047] Further, when the boiling point of the absorbent is lower than that of 1,4-butenediol, the overhead temperature of the absorbent regenerator is 12-40℃, and the bottom temperature is 114-132℃; when the boiling point of the absorbent is higher than that of 1,4-butenediol, the overhead temperature of the absorbent regenerator is 135-140℃, and the bottom temperature is 160-175℃. In an alternative example of the present application, the operating pressure of the absorbent regenerator is 0.5-2 kPaA. Further, when the boiling point of the absorbent is lower than that of 1,4-butenediol, the number of theoretical plates of the absorbent regenerator is 20-25, preferably 20-22; and the feed position is the 15th-16th plate; when the boiling point of the absorbent is higher than that of 1,4-butenediol, the number of theoretical plates of the absorbent regenerator is 20-25, preferably 20-22; and the feed position is the 5th-6th plate.

[0048] 1,4-Butenediol has carbon-carbon double bond, hydroxyl group and adjacent carbon-carbon double bond and hydroxyl group, and the double bond migrates at high temperature, and the isomerization reaction rate is fast, and the content of byproduct 4-hydroxybutyraldehyde increases significantly. In order to reduce the generation of 4-hydroxybutyraldehyde and ensure certain operation flexibility, the present application controls the bottom temperature of the desolventizing column, the light-removing column, the product column, the absorption column and the absorbent regenerator to be 110-180℃, so as to reduce the generation of byproducts in the refining process.

[0049] Further, the first material is coupled with the third tail gas in a heat exchange manner, and the heat in the third tail gas is recovered by heat exchange for heating the first material, so as to reduce the process energy consumption.

[0050] Further, the rich absorbent is heat-coupled with the second tail gas in a heat exchange manner, heat in the second tail gas is input into the rich absorbent through heat exchange, which can reduce the energy consumption of the absorbent regeneration tower and improve the overall process energy utilization efficiency.

[0051] Further, the vacuum system comprises a vacuum pump, and the overhead tail gas of the absorption tower is input into the vacuum pump after deep cooling treatment, so as to further recover 1,4-butenediol in the overhead tail gas of the absorption tower, reduce the polymerization of 1,4-butenediol in the pipeline of the vacuum pump, and prevent the vacuum pump from being blocked.

[0052] In another aspect, the present application provides an on-line scale prevention device for a 1,4-butenediol vacuum system, comprising a decoloring tower, a desolventizing tower, a light component removing tower, a product tower, an absorption tower, an absorbent regeneration tower and a vacuum system; wherein:

[0053] The feed inlet of the decoloring tower is used for inputting a 1,4-butenediol crude product solution to be refined, and the tower kettle of the decoloring tower is connected with the feed inlet of the desolventizing tower;

[0054] The overhead of the desolventizing tower is connected with a first condenser, the liquid phase outlet of the first condenser is used for outputting a solvent; and the tower kettle of the desolventizing tower is connected with the feed inlet of the light component removing tower;

[0055] The overhead of the light component removing tower is connected with a second condenser, the liquid phase outlet of the second condenser is used for outputting a light component material; and the tower kettle of the light component removing tower is connected with the feed inlet of the product tower;

[0056] The overhead of the product tower is connected with a third condenser, the liquid phase outlet of the third condenser is used for outputting a high-purity 1,4-butenediol product;

[0057] The gas phase outlet of the first condenser, the gas phase outlet of the second condenser and the gas phase outlet of the third condenser are connected with the first feed inlet of the absorption tower; the overhead of the absorption tower is connected with a fourth condenser, the gas phase outlet of the fourth condenser is connected with the vacuum system; and the tower kettle of the absorption tower is connected with the feed inlet of the absorbent regeneration tower;

[0058] The overhead or the tower kettle of the absorbent regeneration tower is used for outputting a lean absorbent.

[0059] Based on the above technical scheme, the overhead or the tower kettle of the absorbent regeneration tower used for outputting a lean absorbent is connected with the second feed inlet of the absorption tower; and the tower kettle or the overhead of the absorbent regeneration tower used for outputting a recovered stream is connected with the feed inlet of the light component removing tower.

[0060] Based on the above technical scheme, the tower kettle of the decoloring tower is connected with the desolventizing tower through the first fluid channel of the first heat exchanger, and the gas phase outlet of the third condenser is connected with the first feeding port of the absorption tower through the second fluid channel of the first heat exchanger.

[0061] Based on the above technical scheme, the tower kettle of the decoloring tower is connected with the desolventizing tower through the first fluid channel of the first heat exchanger, and the gas phase outlet of the third condenser is connected with the first feeding port of the absorption tower through the second fluid channel of the first heat exchanger.

[0062] Based on the above technical scheme, the tower kettle of the decoloring tower is connected with the desolventizing tower through the first fluid channel of the first heat exchanger, and the gas phase outlet of the third condenser is connected with the first feeding port of the absorption tower through the second fluid channel of the first heat exchanger.

[0063] Based on the above technical scheme, the tower kettle of the decoloring tower is connected with the desolventizing tower through the first fluid channel of the first heat exchanger, and the gas phase outlet of the third condenser is connected with the first feeding port of the absorption tower through the second fluid channel of the first heat exchanger.

[0064] Based on the above technical scheme, the vacuum system comprises a cryogenic refrigerator and a vacuum pump; the gas phase outlet of the fourth condenser is connected with the cryogenic refrigerator, and the gas phase outlet of the cryogenic refrigerator is connected with the vacuum pump.

[0065] Compared with the prior art, the beneficial effects of the present application are as follows: the crude 1,4-butene diol solution is subjected to adsorption and decoloring treatment by the decoloring tower, so that the chroma of the 1,4-butene diol product is reduced and the purity is improved; the solvent, light component impurities and heavy component impurities in the first material are gradually removed by the desolventizing tower, the light component tower and the product tower, so that high-purity 1,4-butene diol is obtained; in addition, the 1,4-butene diol in the tail gas generated during the operation of the desolventizing tower, the light component tower and the product tower is further absorbed and recovered by the solvent absorption tower, so that the polymerization and accumulation of 1,4-butene diol and by-products in the vacuum pump pipeline can be effectively reduced, the probability of pipeline blockage is reduced, the maintenance frequency is reduced, and the process stability and continuous operation are promoted. The implementation examples prove that the method and device for online scale prevention of the 1,4-butene diol vacuum system can obtain 1,4-butene diol products with a purity of ≥98% at a high yield, and can be continuously operated for ≥200h without abnormal working conditions such as vacuum pump and pipeline blockage. BRIEF DESCRIPTION OF DRAWINGS

[0066] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the present application, and together with the description of the exemplary embodiments of the present application, explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0067] Figure 1 Fig. 1 shows a structure diagram of a device for online scale prevention of a 1,4-butene diol vacuum system according to the present application.

[0068] In the above drawings, the following reference signs are used:

[0069] 1 - decoloring column, 21 - desolventizing column, 22 - light ends column, 23 - product column, 31 - absorber column, 32 - absorbent regenerator column, 4 - vacuum system, 41 - vacuum pump, 51 - first condenser, 52 - second condenser, 53 - third condenser, 54 - fourth condenser, 55 - fifth condenser, 56 - cryogenic vessel, 61 - buffer tank, 62 - solvent receiving tank, 63 - light ends receiving tank, 64 - product tank, 65 - absorbent receiving tank, 66 - cryogenic liquid storage tank. DETAILED DESCRIPTION

[0070] For the purpose of promoting an understanding of the principles of the application, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will, nevertheless, be understood that no limitation of the scope of the application is intended by this specific disclosure, and that the application is to be given full scope only by the appended claims.

[0071] Unless otherwise defined, all technical terms used in the examples below have the same meaning as commonly understood by one of ordinary skill in the art to which the application pertains. The test reagents used in the examples below are routinely available biochemical reagents unless otherwise specified. The experimental methods used in the examples below are routinely available unless otherwise specified.

[0072] In addition, it should also be stated that, in the description of the present application, although the steps of the preparation method of the present application are described in a specific order in this application, these orders are not limiting, and those skilled in the art can perform the steps in different orders without deviating from the basic principles of the present application.

[0073] In addition, the terms "first", "second", "third", etc. are only for descriptive purposes and should not be construed as indicating or implying relative importance or implying the number of the indicated technical features. Therefore, the features defined with "first", "second", "third", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" "at least one" is two or more.

[0074] All numerical designations, including groupings of multiple numbers, are approximations. It should be understood that all numerical designations are approximations. It should be understood, although the term "about" is not always expressly stated before each numerical designation, that the term "about" is inapplicable only where expressly indicated or otherwise evident from the context. It should also be understood that the reagents described herein are merely examples and equivalents are known in the art.

[0075] When equivalent, concentration, or other value or parameter is expressed in a range, a preferred range, or a series of upper preferred values and lower preferred values, it is to be understood that all ranges formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, even if the range is not explicitly disclosed, are to be specifically disclosed. For example, if a range "1-5" is disclosed, then the range "1-4", "1-3", "1-2", "1-2 and 4-5", "1-3 and 5", etc. are to be specifically disclosed. When numerical ranges are disclosed herein, unless otherwise stated, the range is intended to include all integers and fractions within the range.

[0076] The determination method of the chroma in the embodiments of the present application refers to GB / T605-2006, and the measurement method of the chroma is as follows: an appropriate amount of sample solution is subjected to chroma determination at a wavelength of 430 nm by using a spectrophotometer, and compared with a platinum-cobalt standard solution, and the chroma of the sample is calculated. The Hazen unit is as follows: the chroma of a platinum-cobalt solution containing 1 mg of platinum in the form of potassium chloroplatinate (H2PtCl6) and 2 mg of cobalt chloride hexahydrate (CoCl2·6H2O) per liter.

[0077] The compositions of the 1,4-butene diol crude product solutions to be refined in Examples 1-7 are shown in Table 1, wherein the solvent comprises at least one of water, alcohol, ether, and amide. The composition of the 1,4-butene diol crude product solution to be refined in Example 8 is shown in Table 2.

[0078] Table 1

[0079]

[0080] Table 2

[0081]

[0082] Figure 1 A structural diagram of an apparatus for online scale prevention of a 1,4-butene diol vacuum system according to the present application is shown, which comprises a decoloring tower 1, a desolventizing tower 21, a light-removing tower 22, a product tower 23, an absorption tower 31, an absorbent regeneration tower 32, and a vacuum pump 41; wherein:

[0083] The feed inlet of the decoloring tower 1 is used for inputting a 1,4-butene diol crude product solution to be refined, and the tower kettle of the decoloring tower 1 is connected with the feed inlet of the desolventizing tower 21;

[0084] The top of the desolventizing tower is connected with a first condenser 51, and the liquid phase outlet of the first condenser 51 is used for collecting the solvent; the tower kettle of the desolventizing tower 21 is connected with the feed inlet of the light-removing tower 22;

[0085] The overhead of the light-removing column 22 is connected to a second condenser 52, and the liquid phase outlet of the second condenser 52 is used to extract the light component material; the column bottom of the light-removing column 22 is connected to the feed inlet of the product column 23.

[0086] The overhead of the product column 23 is connected to a third condenser 53, and the liquid phase outlet of the third condenser 53 is used to extract the high-purity 1,4-butanediol product.

[0087] The gas phase outlet of the first condenser 51, the gas phase outlet of the second condenser 52, and the gas phase outlet of the third condenser 53 are connected to the first feed inlet of the absorption column 31; the overhead of the absorption column 31 is connected to a fourth condenser 54, the gas phase outlet of the fourth condenser 54 is connected to a deep cooling device 56, and the gas phase outlet of the deep cooling device is connected to a vacuum system 4; the column bottom of the absorption column 31 is connected to the feed inlet of the absorbent regenerating column 32.

[0088] The overhead or the column bottom of the absorbent regenerating column 32 is used to extract the lean absorbent.

[0089] The device is suitable for the condition that the boiling point of the absorbent is not higher than the boiling point of 1,4-butanediol, the solvent is distilled from the overhead of the absorbent regenerating column 32 and recovered, and the recovery stream is extracted from the column bottom. When the boiling point of the absorbent is higher than the boiling point of 1,4-butanediol, the lean absorbent is extracted from the column bottom of the absorbent regenerating column 32, and the recovery stream is extracted from the overhead.

[0090] Optionally, the overhead or the column bottom outlet of the absorbent regenerating column 32 for outputting the lean absorbent is connected to the second feed inlet of the absorption column 31; and the column bottom or the overhead outlet of the absorbent regenerating column 32 for outputting the recovery stream is connected to the feed inlet of the light-removing column 22.

[0091] Optionally, the column bottom of the decoloring column 1 is connected to the desolventizing column 21 through the first fluid passage of a first heat exchanger (not shown in the figure for simplicity), and the gas phase outlet of the third condenser 53 is connected to the first feed inlet of the absorption column 31 through the second fluid passage of the first heat exchanger.

[0092] Optionally, the column bottom of the decoloring column 1 is connected to the desolventizing column 21 through the refrigerant passage of the third condenser 53 (not shown in the figure for simplicity).

[0093] Optionally, the column bottom of the absorption column 31 is connected to the absorbent regenerating column 32 through the first fluid passage of a second heat exchanger (not shown in the figure for simplicity), and the gas phase outlet of the second condenser 52 is connected to the first feed inlet of the absorption column 31 through the second fluid passage of the second heat exchanger.

[0094] Optionally, the column bottom of the absorption column 31 is connected to the absorbent regenerating column 32 through the refrigerant passage of the second condenser 52 (not shown in the figure for simplicity).

[0095] Optionally, the vacuum system 4 comprises a deep cooler 56 and a vacuum pump 41; the gas phase outlet of the fourth condenser 54 is connected to the deep cooler 56, and the gas phase outlet of the deep cooler 56 is connected to the vacuum pump 41. Further optionally, the liquid phase outlet and the gas phase outlet of the deep cooler 56 are connected to a deep cooling liquid storage tank 66, and the deep cooling liquid storage tank 66 is connected to the vacuum pump 41.

[0096] Optionally,

[0097] It is noted that the person skilled in the art can optionally set a buffer tank 61 on the pipeline connecting the decoloring tower 1 and the desolventizing tower 21 to improve the process operation stability; can optionally set a solvent receiving tank 62 for collecting solvent; can optionally set a light component receiving tank 63 for collecting light components; can optionally set a product tank 64 for collecting products; can optionally set an absorbent receiving tank 65 for collecting lean absorbent, and further optionally, the regenerated absorbent is condensed by the fifth condenser 55 and then input into the absorbent receiving tank 65. In addition, in order to improve the flow rate of the streams in the process, the person skilled in the art can optionally set a fan or a circulating pump and the like at a suitable position of the 1,4-butanediol vacuum system online anti-fouling device, and the technical solution thus formed is within the protection scope of the present application. In addition, the person skilled in the art can optionally set a reboiler at a suitable position of the tower kettle of the tower equipment.

[0098] Example 1

[0099] A method for 1,4-butanediol vacuum system online anti-fouling, comprising the following steps:

[0100] (1) The methanol (boiling point 65℃ / 0.1MPaA, 75℃ / 0.15MPaA, 80℃ / 0.2MPaA) solution of 1,4-butanediol after selective hydrogenation of 1,4-butynediol is input into a decoloring tower 1, which is filled with activated carbon as adsorbent, and the specific surface area of the activated carbon is 900m 2 / g, and the bulk density is 0.5g / cm 3 ; the operating temperature of the decoloring tower 1 is 75℃, the operating pressure is 0.2MPaG, the bed pressure drop is 40kPa, and the first material is output.

[0101] (2) The first material is input into a third condenser 53 to exchange heat with the overhead material of a product tower 23, and then is input into a desolventizing tower 21 to desolventize and obtain a second material, and the kettle temperature is 150-160℃, and the operating pressure is 5-10kPaA; the solvent of the liquid phase is recovered after condensation of the overhead material, and the first tail gas is discharged, and the second material is recovered from the kettle.

[0102] (3) The second material is input into the light component removal column 22 to distill out light components, the column bottom temperature is 125-135°C, the operating pressure is 0.5-2 kPaA; the liquid phase light components (residual solvent, 4-hydroxybutyraldehyde, 1,4-butanediol, tail gas absorbent, etc.) are obtained after condensation and the second tail gas is discharged, and the third material is obtained at the column bottom.

[0103] (4) The third material is input into the product column 23, the column bottom temperature is 140-150°C, the operating pressure is 0.5-2 kPaA; the 1,4-butanediol product is obtained after condensation of the column top material and the third tail gas is discharged, and the column bottom liquid is input into the waste liquid incinerator.

[0104] (5) The first tail gas, the second tail gas and the third tail gas are input from the first feeding port at the bottom of the absorption column 31 to absorb the uncondensed 1,4-butanediol contained therein to form the rich solvent of the absorption column 31; the absorbent is ethylene glycol (boiling point 197°C / 0.1 MPaA, 44°C / 0.2 kPaA), the column bottom temperature is 20-30°C, and the operating pressure is 0.5-2 kPaA; when the content of 1,4-butanediol in the solution of the absorption column 31 reaches 20%, the rich absorbent of the absorption column 31 is input into the second condenser 52 to exchange heat with the material at the top of the light component removal column 22, and then is input into the absorbent regeneration column 32, while the regenerated absorbent is supplemented into the absorption column 31; the top and the bottom of the regeneration column are two-way discharged, the column bottom temperature is 120-130°C, and the operating pressure is 0.5-2 kPaA; the absorbent is recovered at the top and is input into the second feeding port of the absorption column 31 for recycling; the 1,4-butanediol is recovered at the column bottom and is input into the light component removal column 22. The results of this embodiment are shown in Table 11.

[0105] To further verify the superiority of the process conditions of the present application, the research and development team used Aspen Plus software to simulate the operation of the desolventizing column 21, the light component removal column 22, the product column 23, the absorption column 31 and the absorbent regeneration column 32 of this embodiment. The simulation results are shown in Table 3.

[0106] Table 3

[0107]

[0108] Example 2

[0109] A method for online scale prevention of a 1,4-butanediol vacuum system, comprising the following steps:

[0110] (1) The 1,4-dioxane (boiling point 101°C / 0.1 MPaA, 59°C / 20 kPaA) solution of 1,4-butanediol after selective hydrogenation of 1,4-butynediol is input into the decoloring column 1, the decoloring column 1 is filled with activated carbon as the adsorbent, the specific surface area of the activated carbon is 1200 m 2 / g, and the bulk density is 0.4 g / cm3 ; the operating temperature of the decoloring tower 1 is 75°C, the operating pressure is 0.3 MPaG, and the bed pressure drop is 50 kPa; and the output is the first material.

[0111] (2) The first material is input into the third condenser 53 to exchange heat with the overhead material of the product tower 23, and then is input into the desolventizing tower 21 to remove the solvent and obtain the second material. The second material is subjected to vacuum distillation, the column bottom temperature is 150-160°C, and the operating pressure is 5-10 kPaA; the solvent is recovered at the top and the first tail gas is discharged, and the second material is collected at the column bottom.

[0112] (3) The second material is input into the light component removal tower 22 to distill off the light components, the column bottom temperature is 130-140°C, and the operating pressure is 0.5-2 kPaA; the overhead material is condensed to obtain the liquid phase light components (residual solvent, 4-hydroxybutyraldehyde, 1,4-butanediol, tail gas absorbent, etc.) and the second tail gas is discharged, and the third material is obtained at the column bottom.

[0113] (4) The third material is input into the product tower 23, the column bottom temperature is 140-150°C, and the operating pressure is 0.5-2 kPaA; the overhead material is condensed to obtain the liquid phase 1,4-butanediol product and the third tail gas is discharged, and the high-boiling substances are collected at the column bottom, and the column bottom liquid is input into the waste liquid incinerator.

[0114] (5) The first tail gas, the second tail gas and the third tail gas are input from the first feed port at the bottom of the absorption tower 31 to absorb the uncondensed 1,4-butanediol contained therein to form the rich solution of the absorption tower 31; the absorbent is 1,3-propanediol (boiling point 188°C / 0.1 MPaA, 63°C / 0.2 kPaA), the column bottom temperature is 20-30°C, and the operating pressure is 0.5-2 kPaA. When the content of 1,4-butanediol in the solution of the absorption tower 31 reaches 20%, the rich absorbent is input into the second condenser 52 to exchange heat with the overhead material of the light component removal tower 22, and then is input into the absorbent regenerating tower 32, and the regenerated absorbent is supplemented into the absorption tower 31, and the material is discharged from the top and the column bottom of the regenerating tower, the column bottom temperature is 120-130°C, and the operating pressure is 0.5-2 kPaA; the absorbent is recovered at the top and is input into the second feed port of the absorption tower 31 for recycling; the 1,4-butanediol is recovered at the column bottom and is transported to the light component removal tower 22. The results of this embodiment are shown in Table 11.

[0115] To further verify the superiority of the process conditions of the present application, the research and development team used Aspen Plus software to simulate the operation of the desolventizing tower 21, the light component removal tower 22, the product tower 23, the absorption tower 31 and the absorbent regenerating tower 32 of this embodiment. The simulation results are shown in Table 4.

[0116] Table 4

[0117]

[0118]

[0119] Example 3

[0120] A method for on-line scale prevention of 1,4-butanediol vacuum system, comprising the following steps:

[0121] (1) The ethylene glycol monomethyl ether (boiling point 124℃ / 0.1MPaA, 67℃ / 10kPaA) solution of 1,4-butanediol after selective hydrogenation of 1,4-butynediol is input into the decoloring tower 1, which is filled with activated carbon as adsorbent, and the specific surface area of the activated carbon is 600m 2 / g, the bulk density is 0.7g / cm 3 ; the operating temperature of the decoloring tower 1 is 90℃, the operating pressure is 0.1MPaG, and the bed pressure drop is 30kPa; the first material is output.

[0122] (2) The first material is input into the third condenser 53 to exchange heat with the overhead material of the product tower 23, and then is input into the desolventizing tower 21 to remove the solvent and obtain the second material, the column bottom temperature is 140-150℃, and the operating pressure is 5-10kPaA; the solvent is recovered at the top and the first tail gas is discharged, and the second material is collected at the column bottom.

[0123] (3) The second material is input into the light component distillation tower 22 to distill the light components, the column bottom temperature is 130-140℃, and the operating pressure is 0.5-2kPaA; the light components (residual solvent, 4-hydroxybutyraldehyde, 1,4-butanediol, etc.) are removed at the top and the second tail gas is discharged, and the third material is obtained at the column bottom.

[0124] (4) The third material is input into the product tower 23, the column bottom temperature is 135-145℃, and the operating pressure is 0.5-2kPaA; the 1,4-butanediol product in liquid phase is obtained at the top after condensation and the third tail gas is discharged, and the column bottom is high boiling point material, which is input into the waste liquid incinerator.

[0125] (5) The first tail gas, the second tail gas, and the third tail gas are fed into the first feed port at the bottom of the absorption tower 31 to absorb the uncondensed 1,4-butenediol contained therein, forming a rich solution in the absorption tower 31; the absorbent is glycerol (boiling point 290℃ / 0.1MPaA, 144℃ / 1kPaA), the tower bottom temperature is 20~30℃, and the operating pressure is 0.5~2kPaA; when the 1,4-butenediol content in the solution of the absorption tower 31 reaches 30%, the solution of the absorption tower 31 is fed into the second condenser 52 to exchange heat with the top material of the light removal tower 22, and then fed into the absorbent regeneration tower 32. At the same time, the regenerated absorbent is added to the absorption tower 31. The regeneration tower has two discharges: the top and the bottom. The bottom temperature is 170~180℃, and the operating pressure is 0.5~2kPaA; the 1,4-butenediol is recovered at the top of the tower and fed into the light removal tower 22; the absorbent is recovered at the bottom of the tower and transported to the absorption tower 31 for recycling. The results of this embodiment are shown in Table 11.

[0126] To further verify the superiority of the process conditions of this invention, the R&D team used Aspen Plus software to simulate the operation of the solvent removal tower 21, light component removal tower 22, product tower 23, absorption tower 31, and absorbent regeneration tower 32 in this embodiment. The simulation results are shown in Table 5.

[0127] Table 5

[0128]

[0129]

[0130] Example 4

[0131] A method for online scale prevention in a 1,4-butenediol vacuum system includes the following steps:

[0132] (1) An ethanol solution (boiling point 78℃ / 0.1MPaA) of 1,4-butynediol after selective hydrogenation is fed into decolorization tower 1. Decolorization tower 1 is filled with activated carbon as an adsorbent, and the specific surface area of ​​the activated carbon is 800 m². 2 / g, bulk density 0.52g / cm³ 3 The decolorization tower 1 operates at a temperature of 75℃, an operating pressure of 0.2 MPaG, and a bed pressure drop of 40 kPa. The output is the first material.

[0133] (2) The first material is fed into the first-stage condenser of product tower 23 to exchange heat with the material at the top of product tower 23, and then fed into the solvent removal tower 21 to remove solvent and obtain the second material. The temperature of the tower bottom is 150-160℃, and the distillation is carried out under normal pressure. The solvent is recovered at the top of the tower and the first tail gas is discharged. The second material is collected from the bottom of the tower.

[0134] (3) The second material is fed into the light component removal tower 22 to distill off the light components. The tower bottom temperature is 130-140℃ and the operating pressure is 0.5-2kPaA. The light components (residual solvent, 4-hydroxybutyraldehyde, 1,4-butanediol, tail gas absorbent, etc.) are removed from the top of the tower and the second tail gas is discharged. The third material is obtained from the tower bottom.

[0135] (4) The third material is fed into product tower 23, with a tower bottom temperature of 135-145℃ and an operating pressure of 0.5-2kPaA. After condensation at the top of the tower, liquid 1,4-butenediol product is obtained and the third tail gas is discharged. The tower bottom is a high-boiling material, and the tower bottom liquid is fed into the waste liquid incinerator.

[0136] (5) The first, second, and third tail gases are fed into the first feed port at the bottom of the absorption tower 31 to absorb the uncondensed 1,4-butenediol contained therein, forming a rich solution absorbent in the absorption tower 31. The absorbent is undecane (boiling point 196℃ / 0.1MPaA, 44℃ / 0.2kPaA), with a tower bottom temperature of 20-30℃ and an operating pressure of 0.5-2kPaA. When the 1,4-butenediol content in the solution of the absorption tower 31 reaches 20%, the solution of the absorption tower 31 is fed into the second condenser 52 to exchange heat with the top material of the light precipitator 22, and then fed into the absorbent regeneration tower 32. At the same time, regenerated absorbent is added to the absorption tower 31, with a tower bottom temperature of 120-130℃ and an operating pressure of 0.5-2kPaA. The absorbent recovered at the top of the tower is fed into the absorption tower 31 for recycling. The 1,4-butenediol recovered at the tower bottom is transported to the light precipitator 22. The results of this embodiment are shown in Table 11.

[0137] To further verify the superiority of the process conditions of this invention, the R&D team used Aspen Plus software to simulate the operation of the solvent removal tower 21, light component removal tower 22, product tower 23, absorption tower 31, and absorbent regeneration tower 32 in this embodiment. The simulation results are shown in Table 6.

[0138] Table 6

[0139]

[0140] Example 5

[0141] A method for online scale prevention in a 1,4-butenediol vacuum system includes the following steps:

[0142] (1) A solution of 1,4-butenediol (boiling point 100℃ / 0.1MPaA, 60℃ / 20kPaA) obtained by selective hydrogenation of 1,4-butynediol was fed into decolorization tower 1. Decolorization tower 1 was filled with activated carbon as an adsorbent, and the specific surface area of ​​the activated carbon was 700 m². 2 / g, bulk density 0.55g / cm³ 3The decolorization tower 1 operates at a temperature of 60℃, an operating pressure of 0.2 MPaG, and a bed pressure drop of 40 kPa. The output is the first material.

[0143] (2) The first material is fed into the first-stage condenser of product tower 23 to exchange heat with the material at the top of product tower 23, and then fed into the solvent removal tower 21 to remove solvent and obtain the second material. The temperature of the tower bottom is 140-150℃ and the operating pressure is 5-10kPaA. The solvent is recovered at the top of the tower and the first tail gas is discharged. The second material is collected from the bottom of the tower.

[0144] (3) The second material is fed into the light component removal tower 22 to distill off the light components. The tower bottom temperature is 130-140℃ and the operating pressure is 0.5-2kPaA. The light components (residual solvent, 4-hydroxybutyraldehyde, 1,4-butanediol, tail gas absorbent, etc.) are removed from the top of the tower and the second tail gas is discharged. The third material is obtained from the tower bottom.

[0145] (4) The third material is fed into product tower 23, with a tower bottom temperature of 130-140℃ and an operating pressure of 0.5-2kPaA. After condensation at the top of the tower, liquid 1,4-butenediol product is obtained and the third tail gas is discharged. The tower bottom is a high-boiling material, and the tower bottom liquid is fed into the waste liquid incinerator.

[0146] (5) The first, second, and third tail gases are fed into the first feed port at the bottom of the absorption tower 31 to absorb the uncondensed 1,4-butenediol contained therein, forming a rich solution in the absorption tower 31; the absorbent is diphenyl ether (boiling point 259℃ / 0.1MPaA, 89℃ / 2kPaA), the tower bottom temperature is 20-30℃, and the operating pressure is 0.5-1.5kPaA; when the 1,4-butenediol content in the solution of the absorption tower 31 reaches 20%, the solution of the absorption tower 31 is fed into the second condenser 52 to exchange heat with the top material of the light-light removal tower 22, and then fed into the absorbent regeneration tower 32, while the regenerated absorbent is replenished into the absorption tower 31; the tower bottom temperature is 130-140℃, and the operating pressure is 0.5-2kPaA; the absorbent recovered at the top of the tower is fed into the absorption tower 31 for recycling; the 1,4-butenediol recovered at the bottom of the tower is transported to the light-light removal tower 22. The results of this embodiment are shown in Table 11.

[0147] To further verify the superiority of the process conditions of this invention, the research and development team used Aspen Plus software to simulate the operation of the solvent removal tower 21, light component removal tower 22, product tower 23, absorption tower 31, and absorbent regeneration tower 32 in this embodiment. The simulation results are shown in Figure 7.

[0148] Table 7

[0149]

[0150] Example 6

[0151] A method for online scale prevention in a 1,4-butenediol vacuum system includes the following steps:

[0152] (1) A methanol solution (boiling point 65℃ / 0.1MPaA, 75℃ / 0.15MPaA, 80℃ / 0.2MPaA) of 1,4-butynediol selectively hydrogenated to 1,4-butenediol is fed into decolorization tower 1. Decolorization tower 1 is filled with activated carbon as an adsorbent, and the specific surface area of ​​the activated carbon is 900 m². 2 / g, bulk density 0.5g / cm³ 3 The decolorization tower 1 operates at a temperature of 75℃, an operating pressure of 0.2 MPaG, and a bed pressure drop of 40 kPa. The output is the first material.

[0153] (2) The first material is fed into the first-stage condenser of product tower 23 to exchange heat with the material at the top of product tower 23, and then fed into the solvent removal tower 21 to remove solvent and obtain the second material. The temperature of the tower bottom is 150-160℃ and 5-10kPaA. The solvent is recovered at the top of the tower and the first tail gas is discharged. The second material is collected from the bottom of the tower.

[0154] (3) The second material is fed into the light component removal tower 22 to distill off the light components. The tower bottom temperature is 130-140℃ and the operating pressure is 0.5-2kPaA. The light components (residual solvent, 4-hydroxybutyraldehyde, 1,4-butanediol, tail gas absorbent, etc.) are removed from the top of the tower and the second tail gas is discharged. The third material is obtained from the tower bottom.

[0155] (4) The third material is fed into product tower 23, with a tower bottom temperature of 135-145℃ and an operating pressure of 0.5-2kPaA. After condensation at the top of the tower, liquid 1,4-butenediol product is obtained and the third tail gas is discharged. The tower bottom is a high-boiling material, and the tower bottom liquid is fed into the waste liquid incinerator.

[0156] (5) The first, second, and third tail gases are fed into the first feed port at the bottom of the absorption tower 31 to absorb the uncondensed 1,4-butenediol contained therein, forming a rich solution in the absorption tower 31. The absorbent is benzonitrile (boiling point 191℃ / 0.1MPaA, 50℃ / 0.2kPaA), the tower bottom temperature is 30-40℃, and the operating pressure is 0.5-2kPaA. When the 1,4-butenediol content in the solution of the absorption tower 31 reaches 30%, the solution of the absorption tower 31 is fed into the second condenser 52 to exchange heat with the top material of the light precipitator 22, and then fed into the absorbent regeneration tower 32, while the regenerated absorbent is replenished into the absorption tower 31. The tower bottom temperature is 110-120℃, and the operating pressure is 0.5-2kPaA. The absorbent recovered at the top of the tower is fed into the absorption tower 31 for recycling. The 1,4-butenediol recovered at the bottom of the tower is transported to the light precipitator 22. The results of this embodiment are shown in Table 11.

[0157] To further verify the superiority of the process conditions of this invention, the R&D team used Aspen Plus software to simulate the operation of the solvent removal tower 21, light component removal tower 22, product tower 23, absorption tower 31, and absorbent regeneration tower 32 in this embodiment. The simulation results are shown in Table 8.

[0158] Table 8

[0159]

[0160]

[0161] Example 7

[0162] A method for online anti-scaling of a 1,4-butenediol vacuum system is disclosed. The process steps and parameter control in this embodiment are the same as in Example 5, except that the crude 1,4-butenediol product solution to be purified is prepared by butadiene acetoxylation. The results of this embodiment are shown in Table 11.

[0163] To further verify the superiority of the process conditions of this invention, the R&D team used Aspen Plus software to simulate the operation of the solvent removal tower 21, light component removal tower 22, product tower 23, absorption tower 31, and absorbent regeneration tower 32 in this embodiment. The simulation results are shown in Table 9.

[0164] Table 9

[0165]

[0166] Example 8

[0167] A method for online scale prevention in a 1,4-butenediol vacuum system is disclosed. The process steps and parameter control in this embodiment are the same as in Embodiment 4, except that the adsorbent packed in the absorption tower 31 is a macroporous resin, and the composition of the crude 1,4-butenediol product solution to be purified is shown in Table 2. The results of this embodiment are shown in Table 11.

[0168] To further verify the superiority of the process conditions of this invention, the R&D team used Aspen Plus software to simulate the operation of the solvent removal tower 21, light component removal tower 22, product tower 23, absorption tower 31, and absorbent regeneration tower 32 in this embodiment. The simulation results are shown in Table 10.

[0169] Table 10

[0170]

[0171]

[0172] Example 9

[0173] A method for purifying 1,4-butenediol is presented in this embodiment. The process steps and parameter control are the same as in Example 4, except that when the 1,4-butenediol content in absorber 31 reaches 40%, it is then fed into absorbent regeneration tower 32 to regenerate the absorbent. In this example, after 150 hours of operation, the pressure increased by 200-300 Pa, and the vacuum pump 41 remained unblocked after 200 hours of stable operation. During the 150-200 hours, the temperature at the bottom and top of absorbent regeneration tower 32 increased by 4-6°C, resulting in a 0.8% decrease in the purity of 1,4-butenediol.

[0174] Example 10

[0175] A method for refining 1,4-butenediol is disclosed in this embodiment. The process steps and parameter control are the same as in Example 4. The difference lies in that when the 1,4-butenediol content in absorber 31 reaches 10%, it is fed into absorbent regeneration tower 32 to regenerate the absorbent. In this embodiment, the 1,4-butenediol content in absorber 31 is lower, which has little impact on the purity and color of 1,4-butenediol. The main difference is that the vacuum pump oil is lighter in color, resulting in a more significant anti-clogging effect, but the overall operating cost increases.

[0176] Comparative Example 1

[0177] A method for purifying 1,4-butenediol. The process steps and parameter control in this embodiment are the same as in Example 4, except that a decolorization tower 1 is not set up.

[0178] Comparative Example 2

[0179] A method for purifying 1,4-butenediol is described in this embodiment. The process steps and parameter control are the same as in Example 4, except that tail gas absorption is not performed. During the operation of this example, butenediol polymerizes in vacuum pump 41, generating a viscous substance that clogs vacuum pump 41. After 150 hours of operation, the vacuum level drops significantly, making it impossible to continue operation.

[0180] Comparative Example 3

[0181] A method for purifying 1,4-butenediol. The process steps and parameter control in this embodiment are the same as in Example 5. The difference is that the crude 1,4-butenediol product solution to be purified is prepared by the 1,4-dichloro-2-butene method, which requires hydrolysis under alkaline conditions and generates a large amount of waste salt.

[0182] The present invention statistically analyzed the process operation data of Examples 1-10 and Comparative Examples 1-3, and the results are shown in Table 11.

[0183] Table 11

[0184] Serial number Product purity / % Colour / Hazen Running time / h Example 1 ≥98.6 29-31 ≥240 Example 2 ≥98.9 28-30 ≥220 Example 3 ≥98.3 30-33 ≥220 Example 4 ≥99.2 29-31 ≥230 Example 5 ≥98.9 29-31 ≥210 Example 6 ≥99.0 30-32 ≥240 Example 7 ≥98.9 34-36 ≥200 Example 8 ≥99.9 31-33 ≥200 Example 9 ≥97.8 32-34 ≥200 Example 10 ≥97.9 28-30 ≥220 Comparative Example 1 ≥97.7 168-170 ≥200 Comparative Example 2 95.2 30-32 150 Comparative Example 3 ≥97.5 32-34 ≥200

[0185] As shown in Table 11, the online anti-scaling method for the 1,4-butenediol vacuum system of the present invention can obtain high-purity, low-color 1,4-butenediol products, meeting the needs of subsequent preparation of other products using 1,4-butenediol as a raw material. Combined with Example 4 and Comparative Example 2, it can be verified that the present invention can effectively prevent the vacuum pump 41 from clogging, promote stable and continuous operation of 1,4-butenediol refining, and has significant economic benefits. Furthermore, the purity of the 1,4-butenediol products obtained by Aspen Plus software in each embodiment of the present invention is consistent with the actual measurement results of the corresponding Example 1, confirming the reliability and reproducibility of the process conditions described in the present invention, and demonstrating that the online anti-scaling method and apparatus for the 1,4-butenediol vacuum system of the present invention have important industrial application value.

[0186] It should be noted that the above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention and should not be construed as limiting the specific implementation of the invention to these descriptions. For those skilled in the art, several simple modifications can be made without departing from the concept of the present invention, and all such modifications should be considered within the scope of protection of the present invention.

Claims

1. A method for online scale prevention in a 1,4-butenediol vacuum system, characterized in that, Includes the following steps: (1) The crude product solution of 1,4-butenediol is fed into a decolorization tower filled with adsorbent and decolorized to obtain the first material. (2) The first material is fed into the solvent removal tower to remove the solvent, and the second material is taken out from the bottom of the solvent removal tower; The product collected from the top of the solvent removal tower is condensed to obtain a liquid solvent, and the first tail gas is also collected. (3) The second material is fed into the light component removal tower, and the third material is collected from the bottom of the light component removal tower; the top product of the light component removal tower is condensed to obtain a liquid light component material, and the second tail gas is collected. (4) The third material is fed into the product tower, and the top product of the product tower is condensed and output as a high-purity 1,4-butenediol product in liquid phase, and the third tail gas is also output. (5) The first tail gas, the second tail gas and the third tail gas are fed into the absorption tower and come into contact with the lean absorbent in the absorption tower. The tail gas at the top of the absorption tower is fed into the vacuum system. The rich absorbent collected from the bottom of the absorption tower is fed into the absorbent regeneration tower and, after regeneration, the lean solvent is recycled back to the absorption tower.

2. The method for online scale prevention in a 1,4-butenediol vacuum system according to claim 1, characterized in that, The mass concentration of 1,4-butenediol in the rich absorbent is 10% to 40%, preferably 20% to 30%. And / or, the rich solvent is regenerated in the absorbent regeneration tower to obtain a recovered stream, which is then fed into the light-duty removal tower.

3. The method for online anti-scaling of a 1,4-butenediol vacuum system according to claim 1 or 2, characterized in that, The absorbent includes at least one solvent selected from hydrocarbons, alcohols, ethers, nitrile, etc. Preferably, the hydrocarbon includes nonane, decane, undecane, dodecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, and eicosane, with undecane and dodecane being more preferred; Preferably, the alcohol includes high-boiling-point monohydric alcohols, dihydric alcohols, and polyhydric alcohols; more preferably, benzyl alcohol, cyclohexanol, n-octanol, isooctanol, ethylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, and glycerol; and even more preferably, ethylene glycol. Preferably, the ether includes phenethyl ether and diphenyl ether, and more preferably phenethyl ether; Preferably, the nitrile includes butadionitrile and benzonitrile, and more preferably benzonitrile.

4. The method for online scale prevention in a 1,4-butenediol vacuum system according to claim 1, characterized in that, The crude 1,4-butenediol product solution contains 20 wt% to 60 wt% 1,4-butenediol, preferably 30 wt% to 50 wt% 1,4-butenediol. Preferably, the crude 1,4-butenediol product solution is prepared by the 1,4-butynediol method or the butadiene acetoxylation method. And / or, the solvent of the crude 1,4-butenediol product solution includes at least one of water, alcohol, ether, and amide; preferably, the alcohol includes at least one of methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, and n-pentanol, and more preferably methanol and ethanol; Preferably, the ether comprises at least one of tetrahydrofuran, 1,4-dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether, and more preferably tetrahydrofuran or 1,4-dioxane. Preferably, the amide includes at least one of N,N-dimethylformamide, N,N-diethylformamide, and N,N-dimethylacetamide, and more preferably N,N-dimethylformamide.

5. The method for online scale prevention in a 1,4-butenediol vacuum system according to claim 1, characterized in that, The adsorbent is a macroporous adsorption resin or activated carbon. Preferably, the specific surface area of ​​the activated carbon is 600–1200 m². 2 / g, preferably 800-1000m 2 / g; bulk density is 0.4~0.7g / cm³ 3 Preferably 0.5~0.6g / cm 3 ; And / or, the operating temperature of the decolorization tower is 60–90°C, preferably 70–80°C; the operating pressure is 0.1–0.3 MPaG, preferably 0.2–0.3 MPaG; and the volumetric hourly space velocity is 0.5–2 h⁻¹. -1 Preferably 1 to 1.5 hours -1 .

6. The method for online scale prevention in a 1,4-butenediol vacuum system according to claim 1, characterized in that, The temperature at the top of the solvent removal column is 15–40°C, the temperature at the bottom of the column is 140–160°C, and the operating pressure is 5–20 kPaA, preferably 5–10 kPaA. And / or, the top temperature of the light-weight removal tower is 70-90°C, the bottom temperature is 130-140°C, and the operating pressure is 0.2-5 kPaA, preferably 0.5-2 kPaA; And / or, the top temperature of the product column is 130-135°C, the bottom temperature is 135-150°C, and the operating pressure is 0.2-5 kPaA, preferably 0.5-2 kPaA; And / or, the top temperature of the absorption tower is 0-5°C, the bottom temperature is 25-40°C, and the operating pressure is 0.2-5 kPaA, preferably 0.5-2 kPaA; And / or, when the boiling point of the absorbent is lower than that of 1,4-butenediol, the top temperature of the absorbent regeneration tower is 12–40°C and the bottom temperature is 114–132°C; when the boiling point of the absorbent is higher than that of 1,4-butenediol, the top temperature of the absorbent regeneration tower is 135–140°C and the bottom temperature is 160–175°C; the operating pressure of the absorbent regeneration tower is 0.2–5 kPaA, preferably 0.5–2 kPaA.

7. The method for online scale prevention in a 1,4-butenediol vacuum system according to claim 1, characterized in that, The first material is coupled to the third exhaust gas via heat exchange. And / or, the rich absorbent is thermally coupled to the second exhaust gas via heat exchange; And / or, the vacuum system includes a vacuum pump, and the exhaust gas from the top of the absorption tower is cryogenically treated before being fed into the vacuum pump.

8. A device for online anti-scaling of a 1,4-butenediol vacuum system, characterized in that, It includes a decolorization tower, a solvent removal tower, a light component removal tower, a product tower, an absorption tower, an absorbent regeneration tower, and a vacuum system; among which: The feed inlet of the decolorization tower is used to input the crude 1,4-butenediol product solution to be purified, and the bottom of the decolorization tower is connected to the feed inlet of the desolventizing tower. The top of the solvent removal column is connected to a first condenser, and the solvent is collected from the liquid phase outlet of the first condenser; the bottom of the solvent removal column is connected to the feed inlet of the light component removal column. The top of the light component removal tower is connected to a second condenser, and the liquid phase outlet of the second condenser collects the light component material; the bottom of the light component removal tower is connected to the feed inlet of the product tower. The top of the product tower is connected to a third condenser, and the liquid phase outlet of the third condenser produces a high-purity 1,4-butenediol product. The gas phase outlets of the first condenser, the second condenser, and the third condenser are connected to the first feed inlet of the absorption tower; the top of the absorption tower is connected to a fourth condenser, and the gas phase outlet of the fourth condenser is connected to the vacuum system; the bottom of the absorption tower is connected to the feed inlet of the absorbent regeneration tower. The absorbent is removed from the top or bottom of the absorbent regeneration tower.

9. The online anti-scaling device for the 1,4-butenediol vacuum system according to claim 8, characterized in that, The absorbent regeneration tower is used to connect the top or bottom outlet of the absorbent regeneration tower to the second inlet of the absorbent tower; the bottom or top outlet of the absorbent regeneration tower is used to connect the recycled stream to the inlet of the light-weight removal tower. And / or, the bottom of the decolorization tower is connected to the solvent removal tower via the first fluid channel of the first heat exchanger, and the gas phase outlet of the third condenser is connected to the first feed inlet of the absorption tower via the second fluid channel of the first heat exchanger; And / or, the bottom of the decolorization tower is connected to the solvent removal tower via the refrigerant channel of the third condenser; And / or, the bottom of the absorption tower is connected to the absorbent regeneration tower via the first fluid channel of the second heat exchanger, and the gas phase of the second condenser is connected to the first feed inlet of the absorption tower via the second fluid channel of the second heat exchanger; and / or, the bottom of the absorption tower is connected to the absorbent regeneration tower via the refrigerant channel of the second condenser.

10. The device for online anti-scaling of a 1,4-butenediol vacuum system according to claim 8 or 9, characterized in that, The vacuum system includes a cryostat and a vacuum pump; the gas phase outlet of the fourth condenser is connected to the cryostat, and the gas phase outlet of the cryostat is connected to the vacuum pump.

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