CN110357763B - Method for separating ethylene glycol and 1, 2-butanediol by extractive distillation - Google Patents
Method for separating ethylene glycol and 1, 2-butanediol by extractive distillation Download PDFInfo
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- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 title claims abstract description 341
- 229940083957 1,2-butanediol Drugs 0.000 title claims abstract description 73
- BMRWNKZVCUKKSR-UHFFFAOYSA-N butane-1,2-diol Chemical compound CCC(O)CO BMRWNKZVCUKKSR-UHFFFAOYSA-N 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 33
- 238000000895 extractive distillation Methods 0.000 title claims abstract description 19
- 238000000605 extraction Methods 0.000 claims abstract description 78
- 238000011084 recovery Methods 0.000 claims abstract description 48
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 39
- 239000000203 mixture Substances 0.000 claims abstract description 34
- 239000002994 raw material Substances 0.000 claims abstract description 20
- 238000000926 separation method Methods 0.000 claims abstract description 20
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000007791 liquid phase Substances 0.000 claims abstract description 7
- 238000004064 recycling Methods 0.000 claims abstract description 6
- 239000012071 phase Substances 0.000 claims description 18
- 238000007670 refining Methods 0.000 claims description 13
- 239000000284 extract Substances 0.000 claims description 6
- KJIOQYGWTQBHNH-UHFFFAOYSA-N undecanol Chemical compound CCCCCCCCCCCO KJIOQYGWTQBHNH-UHFFFAOYSA-N 0.000 claims description 6
- ZJCCRDAZUWHFQH-UHFFFAOYSA-N Trimethylolpropane Chemical group CCC(CO)(CO)CO ZJCCRDAZUWHFQH-UHFFFAOYSA-N 0.000 claims description 5
- GOQYKNQRPGWPLP-UHFFFAOYSA-N heptadecan-1-ol Chemical compound CCCCCCCCCCCCCCCCCO GOQYKNQRPGWPLP-UHFFFAOYSA-N 0.000 claims description 4
- REIUXOLGHVXAEO-UHFFFAOYSA-N pentadecan-1-ol Chemical compound CCCCCCCCCCCCCCCO REIUXOLGHVXAEO-UHFFFAOYSA-N 0.000 claims description 4
- HLZKNKRTKFSKGZ-UHFFFAOYSA-N tetradecan-1-ol Chemical compound CCCCCCCCCCCCCCO HLZKNKRTKFSKGZ-UHFFFAOYSA-N 0.000 claims description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 3
- XFRVVPUIAFSTFO-UHFFFAOYSA-N 1-Tridecanol Chemical compound CCCCCCCCCCCCCO XFRVVPUIAFSTFO-UHFFFAOYSA-N 0.000 claims description 2
- 238000005265 energy consumption Methods 0.000 abstract description 10
- 230000000694 effects Effects 0.000 abstract description 6
- 230000008901 benefit Effects 0.000 abstract description 3
- 239000000047 product Substances 0.000 description 31
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 15
- 238000010992 reflux Methods 0.000 description 9
- GTTSNKDQDACYLV-UHFFFAOYSA-N Trihydroxybutane Chemical compound CCCC(O)(O)O GTTSNKDQDACYLV-UHFFFAOYSA-N 0.000 description 4
- DHKHKXVYLBGOIT-UHFFFAOYSA-N acetaldehyde Diethyl Acetal Natural products CCOC(C)OCC DHKHKXVYLBGOIT-UHFFFAOYSA-N 0.000 description 4
- 125000002777 acetyl group Chemical class [H]C([H])([H])C(*)=O 0.000 description 4
- CDQSJQSWAWPGKG-UHFFFAOYSA-N butane-1,1-diol Chemical compound CCCC(O)O CDQSJQSWAWPGKG-UHFFFAOYSA-N 0.000 description 4
- HXJUTPCZVOIRIF-UHFFFAOYSA-N sulfolane Chemical compound O=S1(=O)CCCC1 HXJUTPCZVOIRIF-UHFFFAOYSA-N 0.000 description 4
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 3
- 150000002576 ketones Chemical class 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000002028 Biomass Substances 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 125000000524 functional group Chemical group 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- LCEDQNDDFOCWGG-UHFFFAOYSA-N morpholine-4-carbaldehyde Chemical compound O=CN1CCOCC1 LCEDQNDDFOCWGG-UHFFFAOYSA-N 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 238000005191 phase separation Methods 0.000 description 2
- 239000003495 polar organic solvent Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- WFSMVVDJSNMRAR-UHFFFAOYSA-N 2-[2-(2-ethoxyethoxy)ethoxy]ethanol Chemical compound CCOCCOCCOCCO WFSMVVDJSNMRAR-UHFFFAOYSA-N 0.000 description 1
- UWHCKJMYHZGTIT-UHFFFAOYSA-N Tetraethylene glycol, Natural products OCCOCCOCCOCCO UWHCKJMYHZGTIT-UHFFFAOYSA-N 0.000 description 1
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 208000012839 conversion disease Diseases 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- LVTYICIALWPMFW-UHFFFAOYSA-N diisopropanolamine Chemical compound CC(O)CNCC(C)O LVTYICIALWPMFW-UHFFFAOYSA-N 0.000 description 1
- 229940043276 diisopropanolamine Drugs 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- NWVVVBRKAWDGAB-UHFFFAOYSA-N p-methoxyphenol Chemical compound COC1=CC=C(O)C=C1 NWVVVBRKAWDGAB-UHFFFAOYSA-N 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- ZIBGPFATKBEMQZ-UHFFFAOYSA-N triethylene glycol Chemical compound OCCOCCOCCO ZIBGPFATKBEMQZ-UHFFFAOYSA-N 0.000 description 1
- JLGLQAWTXXGVEM-UHFFFAOYSA-N triethylene glycol monomethyl ether Chemical compound COCCOCCOCCO JLGLQAWTXXGVEM-UHFFFAOYSA-N 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
- C07C29/84—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation by extractive distillation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
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- Chemical & Material Sciences (AREA)
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to a method for separating ethylene glycol and 1, 2-butanediol by extractive distillation, which comprises the following process flows: feeding a mixture of raw materials of ethylene glycol and 1, 2-butanediol with any composition at a certain position of an extraction and rectification tower, simultaneously feeding an extracting agent at the upper part of the extraction and rectification tower, extracting the 1, 2-butanediol from the top of the tower in the extraction and rectification tower, and feeding the ethylene glycol and the extracting agent into an extracting agent recovery tower after the ethylene glycol and the extracting agent are extracted from a tower kettle; in an extractant recovery tower, glycol products are extracted from the top of the tower, the extractant is extracted from the bottom of the tower, then exchanges heat with the raw materials through a heat exchanger, and then returns to a feed inlet at the upper part of an extraction rectifying tower through a cooler for recycling, and meanwhile, the extractant lost from the tops of the two rectifying towers is supplemented at the feed inlet at the upper part of the extraction rectifying tower; the extraction rectifying tower and the extractant recovery tower are both operated under negative pressure, and the pressure at the top of the tower is below 10 kPa. The method separates the system by using a liquid-phase high-boiling-point extractant to obtain a 1, 2-butanediol product and an ethylene glycol product with the mole fraction of 99.9 percent, and has the advantages of simple process, low equipment investment, low energy consumption and good separation effect.
Description
Technical Field
The invention belongs to the technical field of separation of ethylene glycol and 1, 2-butanediol, and relates to a method for separating ethylene glycol and 1, 2-butanediol by extractive distillation.
Background
In the process of preparing ethylene glycol from coal and preparing ethylene glycol from biomass, byproducts are generated, in order to ensure the indexes of ethylene glycol products, a byproduct stream containing ethylene glycol is extracted in the separation and purification process, and the stream contains products such as ethylene glycol, propylene glycol, butanediol and the like. Among these products, ethylene glycol and 1, 2-butanediol have azeotropic points, which leads to the 1, 2-butanediol in the raw material and ethylene glycol forming an azeotrope being distilled out from the top of the column, resulting in a decrease in the yield of ethylene glycol. Therefore, how to separate 1, 2-butanediol from ethylene glycol products with high efficiency and energy conservation is one of the technical problems to be solved in the preparation of ethylene glycol from coal and the preparation of ethylene glycol from biomass.
Patent CN 102372598A proposes an adsorption method, in which at least one of non-functional resin or molecular sieve is used as adsorbent, butanediol is adsorbed, and the raffinate is 99.99% or 100% (mass fraction) of ethylene glycol. However, this method has a limitation on the content of butanediol in the raw material to be treated, and the content of butanediol is required to be not higher than 3%.
Patent CN 105622338A proposes a separation method, process and apparatus for reversible reaction conversion, in which ethylene glycol and 1, 2-butanediol react through acetal or ketal to form a corresponding acetal/ketone product liquid mixture, the liquid mixture is separated through a series of rectification towers, then acetal/ketone products are hydrolyzed respectively to obtain ethylene glycol and 1, 2-butanediol primary products, and finally rectification and purification are performed respectively to obtain ethylene glycol of more than 99.9% and 1, 2-butanediol products of more than 98.5%. The method changes the difficult problem of separating the ethylene glycol and the 1, 2-butanediol into the problem of separating an acetal/ketone product which is easy to separate, but the separation process is too complex, and the ethylene glycol and the 1, 2-butanediol product can be obtained only by reacting, rectifying, re-reacting and re-rectifying the raw materials.
Disclosure of Invention
The method for separating the ethylene glycol and the 1, 2-butanediol by extractive distillation is provided aiming at the problems that the common distillation needs high energy consumption and high equipment investment, the separation effect is not good and the recovery rate of the ethylene glycol is low because the ethylene glycol and the 1, 2-butanediol have the lowest azeotrope in the current industrial production separation of the ethylene glycol and the 1, 2-butanediol. The method separates the system by using a liquid-phase high-boiling point extracting agent to obtain a 1, 2-butanediol product and an ethylene glycol product with the mole fraction of 99.9 percent. The method has the advantages of simple process, low equipment investment, low energy consumption and good separation effect.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the first scheme is as follows: a method for separating ethylene glycol and 1, 2-butanediol by extractive distillation comprises the following process flows: feeding a mixture of raw materials of ethylene glycol and 1, 2-butanediol with any composition at a certain position of an extraction and rectification tower, simultaneously feeding an extracting agent at the upper part of the extraction and rectification tower, extracting the 1, 2-butanediol from the top of the tower in the extraction and rectification tower, and feeding the ethylene glycol and the extracting agent into an extracting agent recovery tower after the ethylene glycol and the extracting agent are extracted from a tower kettle; in an extractant recovery tower, glycol products are extracted from the top of the tower, the extractant is extracted from a tower bottom and then exchanges heat with the raw materials through a heat exchanger, and then returns to a feed inlet at the upper part of an extraction rectifying tower through a cooler for recycling, and meanwhile, the extractant lost from the tops of the two rectifying towers is supplemented at the feed inlet at the upper part of the extraction rectifying tower, so that the separation of azeotrope system glycol and 1, 2-butanediol is finally realized;
the extractant is one or more high-boiling-point liquid phase extractants in a polar organic solvent containing more than two hydroxyl groups or an organic solvent containing more polar functional groups;
1, 2-butanediol product with the mole fraction of 99.9 percent is extracted from the top of the extraction rectifying tower, ethylene glycol product with the mole fraction of 99.9 percent is extracted from the top of the extractant recovery tower, and extractant with the mole fraction of 99.99 percent is extracted from the bottom of the tower;
the second scheme is as follows: a method for separating ethylene glycol and 1, 2-butanediol by extractive distillation comprises the following process flows: feeding a mixture of raw materials of ethylene glycol and 1, 2-butanediol with any composition at a certain position of an extraction and rectification tower, simultaneously feeding an extracting agent at the upper part of the extraction and rectification tower, extracting the ethylene glycol and part of the extracting agent from the top of the extraction and rectification tower, then feeding the mixture into a phase splitter for phase splitting, wherein the light phase contains more extracting agent, and returning the light phase to the top of the extraction and rectification tower; the heavy phase contains much glycol and enters an ethylene glycol refining tower, the ethylene glycol product is extracted from the tower bottom, the mixture of the ethylene glycol and the extractant is taken from the tower top, and the mixture returns to the same phase separator after being cooled by a cooler;
1, 2-butanediol and an extractant are extracted from a tower kettle of an extraction rectifying tower and then enter an extractant recovery tower, in the extractant recovery tower, a 1, 2-butanediol product is extracted from the tower top, the extractant is extracted from the tower kettle and then exchanges heat with a raw material through a heat exchanger, and then returns to a feed inlet at the upper part of the extraction rectifying tower for recycling through a cooler, and meanwhile, the extractant lost from two rectifying towers (the tower kettle of an ethylene glycol refining tower and the tower top of the extractant recovery tower) is supplemented at the feed inlet at the upper part of the extraction rectifying tower, so that the separation of an azeotrope system, namely ethylene glycol and 1, 2-butanediol is finally realized;
the extractant is high-boiling-point liquid-phase long-chain alcohol;
the ethylene glycol product with the mole fraction of 99.9 percent is extracted from the tower bottom of the ethylene glycol refining tower, the 1, 2-butanediol product with the mole fraction of 99.9 percent is extracted from the tower top of the extractant recovery tower, and the extractant with the mole fraction of 99.99 percent is extracted from the tower bottom;
compared with the prior art, the invention has the beneficial effects that:
1) the product purity of the ethylene glycol and the 1, 2-butanediol obtained by the method is high and can reach 99.9 percent (mole fraction), and the yield of the ethylene glycol and the 1, 2-butanediol is high and can reach 99 percent.
2) The extractant used in the application is a high-boiling-point liquid phase extractant which is not easy to volatilize, and the extractant is extracted from a tower kettle. Compared with the common rectification separation, the two separation schemes improve the separation effect and reduce the energy consumption. In the second scheme, a continuous extraction and rectification mode is adopted for the long-chain alcohol extractant, so that the requirements of high purity and high recovery rate are met. The first scheme realizes the requirements of high purity and high recovery rate, and has remarkable energy-saving effect, the treatment capacity in example 2 is 10kmol/h, and when the feeding mole fractions are 90% of 1, 2-butanediol and 10% of ethylene glycol, the energy consumption can be reduced to 259.94kW, and the energy-saving effect and the economic benefit are remarkable.
3) The extractant is extracted from the tower kettle and then exchanges heat with the raw material through the heat exchanger, and then returns to the feed inlet at the upper part of the extraction rectifying tower through the cooler, so that the heat exchange between the circulating extractant and the raw material is correspondingly considered in energy consumption, and the energy consumption is further reduced.
Drawings
FIG. 1 is a process flow diagram of a first embodiment of the process for the extractive distillation separation of ethylene glycol and 1, 2-butanediol according to the invention, examples 1 to 3.
FIG. 2 is a flow chart of a second embodiment of the method for separating ethylene glycol and 1, 2-butanediol by extractive distillation, which is a process flow chart of example 4.
Detailed Description
The present invention is further explained with reference to the following examples and drawings, but the scope of the present invention is not limited thereto.
As shown in figure 1, a mixture (with any ratio) of raw materials of ethylene glycol and 1, 2-butanediol is fed at a certain position of an extraction and rectification tower, an extracting agent is fed at the upper part of the extraction and rectification tower, 1, 2-butanediol is extracted from the top of the extraction and rectification tower, the ethylene glycol and the extracting agent are extracted from a tower bottom and then enter an extracting agent recovery tower, an ethylene glycol product is extracted from the top of the extracting agent recovery tower, the extracting agent exchanges heat with the raw materials through a heat exchanger after being extracted from the tower bottom, and then the heat exchange liquid returns to a feed inlet at the upper part of the extraction and rectification tower through a cooler for recycling, and the extracting agent is supplemented at the upper part of the extraction and rectification tower properly, so that the separation of an azeotrope system of ethylene glycol and 1, 2-butanediol is finally realized. The extraction rectification tower extracts a 1, 2-butanediol product with the mole fraction of 99.9% from the top of the extraction rectification tower, extracts an ethylene glycol product with the mole fraction of 99.9% from the top of the extractant recovery tower, and extracts an extractant with the mole fraction of 99.99% from the bottom of the extraction rectification tower. The extractant only needs to be supplemented with the extractant lost from the tops of the two rectifying towers.
As shown in fig. 2, a mixture (in any ratio) of raw materials of ethylene glycol and 1, 2-butanediol is fed at a certain position of an extraction and rectification tower, meanwhile, an extracting agent is fed at the upper part of the extraction and rectification tower, in the extraction and rectification tower, the ethylene glycol and part of the extracting agent are extracted from the top of the tower, and then enter a phase separator for phase separation, and a light phase contains more extracting agent and returns to the top of the extraction and rectification tower; the heavy phase contains much glycol and enters an ethylene glycol refining tower, the ethylene glycol product is extracted from the tower bottom, the mixture of the ethylene glycol and the extractant is taken from the tower top, and the mixture returns to the same phase separator after being cooled by a cooler; 1, 2-butanediol and an extracting agent are extracted from the bottom of an extraction rectifying tower and then enter an extracting agent recovery tower, in the extracting agent recovery tower, a 1, 2-butanediol product is extracted from the top of the tower, the extracting agent is extracted from the bottom of the tower, then exchanges heat with raw materials through a heat exchanger, and then returns to a feed inlet at the upper part of the extraction rectifying tower for cyclic utilization after passing through a cooler, and finally separation of an azeotrope system ethylene glycol and the 1, 2-butanediol is realized. The ethylene glycol product with the mole fraction of 99.9 percent is extracted from the tower bottom of the ethylene glycol refining tower, the 1, 2-butanediol product with the mole fraction of 99.9 percent is extracted from the tower top of the extractant recovery tower, and the extractant with the mole fraction of 99.99 percent is extracted from the tower bottom. The extractant only needs to supplement the extractant lost from the two rectifying towers (the tower bottom of the ethylene glycol refining tower and the tower top of the extractant recovery tower).
All the rectifying towers (the extraction rectifying tower, the extractant recovery tower and the ethylene glycol refining tower) are operated under negative pressure, and the tower top pressure is below 10 kPa.
The extraction agent is a high-boiling point and low-volatility liquid phase extraction agent, and when the extraction agent is one or more of polar organic solvents with more (more than two) hydroxyl groups or organic solvents with more polar functional groups, such as glycerol, butanetriol, triethylene glycol, tetraethylene glycol, trimethylolpropane, sulfolane, triethanolamine, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, diisopropanolamine, p-hydroxyanisole, N-formylmorpholine and the like, the process flow is shown in figure 1; when the extractant is one or more of long-chain alcohols such as undecanol, tridecanol, tetradecanol, pentadecanol, and heptadecanol, the process flow is shown in FIG. 2.
Example 1
As shown in the figure 1, the extractive distillation tower has 52 theoretical plates, the reflux ratio is 1.75, the extracting agent is sulfolane, the extractive distillation tower is fed from the 19 th theoretical plate (counted from the top of the tower to the bottom of the tower) and the flow rate is 20.5 kmol/h; a mixture of ethylene glycol and 1, 2-butanediol, with mole fractions of 50% 1, 2-butanediol and 50% ethylene glycol, was fed from the 38 th theoretical plate at a flow rate of 10 kmol/h. The top pressure of the extraction and rectification tower is 10kPa, the temperature of the top of the tower is 132.2 ℃, the temperature of the bottom of the tower is 169.8 ℃, 99.9mol percent of 1, 2-butanediol is extracted from the top of the tower, and the extraction amount is 5 kmol/h; a mixture of ethylene glycol and sulfolane is obtained at the tower bottom and enters an extractant recovery tower from the 8 th theoretical plate, the extractant recovery tower is provided with 15 theoretical plates, the reflux ratio is 0.62, the pressure at the top of the tower is 10kPa, the temperature at the top of the tower is 132.7 ℃, the temperature at the tower bottom is 200.1 ℃, 99.9 mol% of ethylene glycol product is extracted at the top of the tower, and the extraction amount is 5 kmol/h; the sulfolane as extractant is obtained from the bottom of the extractant recovery tower, and the purity can reach 99.99 mol%. The recovery rate of the 1, 2-butanediol product is 99.95 percent, and the recovery rate of the ethylene glycol product is 99.87 percent.
Example 2
As shown in figure 1, the extractive distillation column has 62 theoretical plates, the reflux ratio is 0.43, the extractant is trimethylolpropane, and the 5 th theoretical plate is fed with the flow rate of 11 kmol/h; a mixture of ethylene glycol and 1, 2-butanediol, with molar fractions of 90% 1, 2-butanediol and 10% ethylene glycol, was fed from the 20 th theoretical plate at a flow rate of 10 kmol/h. The top pressure of the extraction and rectification tower is 6kPa, the temperature of the top of the tower is 120.9 ℃, the temperature of the bottom of the tower is 199.5 ℃, the extraction amount at the top of the tower is 9kmol/h, and 99.9mol percent of 1, 2-butanediol is extracted at the top of the tower; a mixture of ethylene glycol and trimethylolpropane is obtained at the tower bottom and enters an extractant recovery tower from the 6 th theoretical plate, the extractant recovery tower is provided with 9 theoretical plates, the reflux ratio is 1.21, the pressure at the top of the tower is 6kPa, the temperature at the top of the tower is 121.3 ℃, the temperature at the tower bottom is 211.9 ℃, the extraction amount at the top of the tower is 1kmol/h, and 99.9 mol% of ethylene glycol is extracted at the top of the tower; the extractant trimethylolpropane is obtained at the bottom of the tower, and the purity can reach 99.99 mol%. The recovery rate of 1, 2-butanediol was 99.99%, and the recovery rate of ethylene glycol was 99.00%.
Example 3
As shown in figure 1, the extractive distillation column has 70 theoretical plates, the reflux ratio is 11.90, the extractant is a mixture of butanetriol and glycerol, wherein the glycerol accounts for 90mol percent, the 5 th theoretical plate is used for feeding, and the flow rate is 28 kmol/h; a mixture of ethylene glycol and 1, 2-butanediol, with mole fractions of 20% 1, 2-butanediol and 80% ethylene glycol, was fed from a 43 th theoretical plate at a flow rate of 10 kmol/h. The top pressure of the extraction and rectification tower is 1kPa, the temperature of the top of the tower is 86.9 ℃, the temperature of the bottom of the tower is 155.3 ℃, the extraction amount at the top of the tower is 2kmol/h, and 99.9mol percent of 1, 2-butanediol is extracted at the top of the tower; the mixture of glycol, glycerol and butanetriol obtained at the tower bottom enters an extractant recovery tower from the 11 th plate, the extractant recovery tower is provided with 20 theoretical plates, the reflux ratio is 0.31, the pressure at the top of the tower is 1kPa, the temperature at the top of the tower is 86.6 ℃, the temperature at the tower bottom is 175.7 ℃, the extraction amount at the top of the tower is 8kmol/h, and 99.9 mol% of glycol is extracted at the top of the tower; the mixture of the extracting agents of the glycerol and the butanetriol is obtained at the bottom of the tower, and the total purity can reach 99.99mol percent. The recovery rate of 1, 2-butanediol was 99.90%, and the recovery rate of ethylene glycol was 99.94%.
Example 4
Referring to FIG. 2, the extractive distillation column has 102 theoretical plates, the reflux ratio is 3, the extractant is undecanol, the 2 nd theoretical plate is fed with the flow rate of 21.5 kmol/h; a mixture of ethylene glycol and 1, 2-butanediol, with mole fractions of 50% 1, 2-butanediol and 50% ethylene glycol, was fed from the 67 th theoretical plate at a flow rate of 10 kmol/h. The pressure of the top of the extraction rectifying tower is 10kPa, the temperature of the top of the extraction rectifying tower is 130.6 ℃, the temperature of the bottom of the extraction rectifying tower is 202.9 ℃, the mixture of ethylene glycol and undecanol is extracted from the top of the extraction rectifying tower, the light phase after phase separation returns to the extraction rectifying tower, the heavy phase enters the ethylene glycol refining tower from the 4 th theoretical plate, the ethylene glycol refining tower has 14 theoretical plates, the reflux ratio is 0.22, the pressure of the top of the extraction rectifying tower is 10kPa, the temperature of the top of the extraction rectifying tower is 130.6 ℃, the temperature of the bottom of the extraction rectifying tower is 146.6 ℃, and 99.9mol percent of ethylene glycol is extracted from the bottom of the extraction rectifying tower. A mixture of ethylene glycol and undecanol is obtained at the bottom of the extractive distillation tower, and enters an extractant recovery tower from the 40 th plate, the extractant recovery tower is provided with 44 theoretical plates, the reflux ratio is 3.62, the pressure at the top of the tower is 10kPa, the temperature at the top of the tower is 132.3 ℃, the temperature at the bottom of the tower is 207.6 ℃, the extraction amount at the top of the tower is 5kmol/h, and 99.9 mol% of 1, 2-butanediol is extracted at the top of the tower; the extractant undecanol is obtained at the bottom of the column, and the purity is 99.99 mol%. The recovery rate of 1, 2-butanediol was 99.86%, and the recovery rate of ethylene glycol was 99.94%.
Table 1 total reboiler energy consumption for the overall process for each example
| Examples | 1 | 2 | 3 | 4 |
| Energy consumption (kW) | 371.41 | 259.94 | 636.55 | 1132.91 |
The method has no requirement on the feeding composition of the raw materials, the purity and the recovery rate of the obtained ethylene glycol and 1, 2-butanediol are high, and the scheme in the embodiment 4 has higher energy consumption compared with the embodiment 1-3, but can realize that the ethylene glycol is obtained from the top of an extractive distillation tower and then refined to obtain an ethylene glycol product (different from the embodiment 1-3, the ethylene glycol is obtained from the bottom of the extractive distillation tower), and has lower cost compared with the existing rectification separation method.
Nothing in this specification is said to apply to the prior art.
Claims (3)
1. A method for separating ethylene glycol and 1, 2-butanediol by extractive distillation comprises the following process flows: feeding a mixture of raw materials of ethylene glycol and 1, 2-butanediol with any composition at a certain position of an extraction and rectification tower, simultaneously feeding an extracting agent at the upper part of the extraction and rectification tower, extracting the 1, 2-butanediol from the top of the tower in the extraction and rectification tower, and feeding the ethylene glycol and the extracting agent into an extracting agent recovery tower after the ethylene glycol and the extracting agent are extracted from a tower kettle; in an extractant recovery tower, glycol products are extracted from the top of the tower, the extractant is extracted from a tower bottom and then exchanges heat with the raw materials through a heat exchanger, and then returns to a feed inlet at the upper part of an extraction rectifying tower through a cooler for recycling, and meanwhile, the extractant lost from the tops of the two rectifying towers is supplemented at the feed inlet at the upper part of the extraction rectifying tower, so that the separation of azeotrope system glycol and 1, 2-butanediol is finally realized;
the extraction rectifying tower and the extractant recovery tower are both operated under negative pressure, and the pressure at the top of the tower is below 10 kPa;
the extractant is trimethylolpropane;
the extraction rectification tower extracts a 1, 2-butanediol product with the mole fraction of 99.9% from the top of the extraction rectification tower, extracts an ethylene glycol product with the mole fraction of 99.9% from the top of the extractant recovery tower, and extracts an extractant with the mole fraction of 99.99% from the bottom of the extraction rectification tower.
2. A method for separating ethylene glycol and 1, 2-butanediol by extractive distillation comprises the following process flows: feeding a mixture of raw materials of ethylene glycol and 1, 2-butanediol with any composition at a certain position of an extraction and rectification tower, simultaneously feeding an extracting agent at the upper part of the extraction and rectification tower, extracting the ethylene glycol and part of the extracting agent from the top of the extraction and rectification tower, then feeding the mixture into a phase splitter for phase splitting, wherein the light phase contains more extracting agent, and returning the light phase to the top of the extraction and rectification tower; the heavy phase contains much glycol and enters an ethylene glycol refining tower, the ethylene glycol product is extracted from the tower bottom, the mixture of the ethylene glycol and the extractant is taken from the tower top, and the mixture returns to the same phase separator after being cooled by a cooler;
1, 2-butanediol and an extractant are extracted from a tower bottom of an extraction rectification tower and then enter an extractant recovery tower, in the extractant recovery tower, a 1, 2-butanediol product is extracted from the tower top, the extractant is extracted from the tower bottom and then exchanges heat with a raw material through a heat exchanger, the heat exchanged extractant is returned to a feed inlet at the upper part of the extraction rectification tower through a cooler for recycling, meanwhile, the extractant lost from the tower bottom of an ethylene glycol refining tower and the top of the extractant recovery tower is supplemented at the feed inlet at the upper part of the extraction rectification tower, and finally, the separation of an azeotrope system ethylene glycol and the 1, 2-butanediol is realized;
the extraction rectifying tower, the ethylene glycol refining tower and the extractant recovery tower are all operated under negative pressure, and the pressure at the top of the tower is below 10 kPa;
the extraction agent is high-boiling-point liquid-phase long-chain alcohol, and the extraction agent is one or more of undecanol, tridecanol, tetradecanol, pentadecanol and heptadecanol.
3. The method of claim 2, wherein the ethylene glycol product with the mole fraction of 99.9% is extracted from the bottom of the ethylene glycol refining tower, the 1, 2-butanediol product with the mole fraction of 99.9% is extracted from the top of the extractant recovery tower, and the extractant with the mole fraction of 99.99% is extracted from the bottom of the extraction tower.
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| CN117616005A (en) * | 2021-04-19 | 2024-02-27 | 可口可乐公司 | Recovery of monoethylene glycol |
| CN115304455B (en) * | 2021-05-07 | 2024-07-23 | 中国石油化工股份有限公司 | Purification method and system for recycling glycol in polyester production process |
| CN114591145A (en) * | 2022-03-25 | 2022-06-07 | 广西科技大学 | Method for separating dihydric fusel from ethylene glycol by double-solvent synergistic extraction |
| CN114853573B (en) * | 2022-05-27 | 2023-06-13 | 辽宁石油化工大学 | Separation and purification method and system for 1, 4-butanediol |
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