CN114394894A - Method and device for extracting high-purity heptanoic acid from side line by vacuum batch rectification - Google Patents
Method and device for extracting high-purity heptanoic acid from side line by vacuum batch rectification Download PDFInfo
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- MNWFXJYAOYHMED-UHFFFAOYSA-N heptanoic acid Chemical compound CCCCCCC(O)=O MNWFXJYAOYHMED-UHFFFAOYSA-N 0.000 title claims abstract description 119
- 238000000034 method Methods 0.000 title claims abstract description 32
- 238000010992 reflux Methods 0.000 claims abstract description 41
- 239000002994 raw material Substances 0.000 claims abstract description 19
- 230000007704 transition Effects 0.000 claims abstract description 14
- 238000001816 cooling Methods 0.000 claims abstract description 9
- WWZKQHOCKIZLMA-UHFFFAOYSA-N octanoic acid Chemical compound CCCCCCCC(O)=O WWZKQHOCKIZLMA-UHFFFAOYSA-N 0.000 claims description 40
- 238000000998 batch distillation Methods 0.000 claims description 30
- 238000000605 extraction Methods 0.000 claims description 26
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 18
- FUZZWVXGSFPDMH-UHFFFAOYSA-N hexanoic acid Chemical compound CCCCCC(O)=O FUZZWVXGSFPDMH-UHFFFAOYSA-N 0.000 claims description 14
- NQPDZGIKBAWPEJ-UHFFFAOYSA-N valeric acid Chemical compound CCCCC(O)=O NQPDZGIKBAWPEJ-UHFFFAOYSA-N 0.000 claims description 14
- OBETXYAYXDNJHR-UHFFFAOYSA-N alpha-ethylcaproic acid Natural products CCCCC(CC)C(O)=O OBETXYAYXDNJHR-UHFFFAOYSA-N 0.000 claims description 13
- FERIUCNNQQJTOY-UHFFFAOYSA-N Butyric acid Chemical compound CCCC(O)=O FERIUCNNQQJTOY-UHFFFAOYSA-N 0.000 claims description 12
- 229940005605 valeric acid Drugs 0.000 claims description 7
- 239000003507 refrigerant Substances 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 238000004821 distillation Methods 0.000 claims 2
- 239000000047 product Substances 0.000 description 40
- 229960002446 octanoic acid Drugs 0.000 description 18
- 239000012535 impurity Substances 0.000 description 9
- 230000008569 process Effects 0.000 description 9
- 239000007788 liquid Substances 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- AWQSAIIDOMEEOD-UHFFFAOYSA-N 5,5-Dimethyl-4-(3-oxobutyl)dihydro-2(3H)-furanone Chemical compound CC(=O)CCC1CC(=O)OC1(C)C AWQSAIIDOMEEOD-UHFFFAOYSA-N 0.000 description 6
- 239000004229 Alkannin Substances 0.000 description 6
- 239000005635 Caprylic acid (CAS 124-07-2) Substances 0.000 description 6
- 238000012856 packing Methods 0.000 description 6
- 238000011084 recovery Methods 0.000 description 5
- 238000000926 separation method Methods 0.000 description 5
- 238000012546 transfer Methods 0.000 description 5
- 239000003054 catalyst Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- FXHGMKSSBGDXIY-UHFFFAOYSA-N heptanal Chemical compound CCCCCCC=O FXHGMKSSBGDXIY-UHFFFAOYSA-N 0.000 description 4
- 239000012808 vapor phase Substances 0.000 description 4
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 3
- 150000001299 aldehydes Chemical class 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 239000000945 filler Substances 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- 239000004149 tartrazine Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 2
- GONOPSZTUGRENK-UHFFFAOYSA-N benzyl(trichloro)silane Chemical compound Cl[Si](Cl)(Cl)CC1=CC=CC=C1 GONOPSZTUGRENK-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
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- 239000000126 substance Substances 0.000 description 2
- GWHCXVQVJPWHRF-KTKRTIGZSA-N (15Z)-tetracosenoic acid Chemical compound CCCCCCCC\C=C/CCCCCCCCCCCCCC(O)=O GWHCXVQVJPWHRF-KTKRTIGZSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- XJXROGWVRIJYMO-SJDLZYGOSA-N Nervonic acid Natural products O=C(O)[C@@H](/C=C/CCCCCCCC)CCCCCCCCCCCC XJXROGWVRIJYMO-SJDLZYGOSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
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- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000006315 carbonylation Effects 0.000 description 1
- 238000005810 carbonylation reaction Methods 0.000 description 1
- 239000004359 castor oil Substances 0.000 description 1
- 235000019438 castor oil Nutrition 0.000 description 1
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- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000004587 chromatography analysis Methods 0.000 description 1
- GWHCXVQVJPWHRF-UHFFFAOYSA-N cis-tetracosenoic acid Natural products CCCCCCCCC=CCCCCCCCCCCCCCC(O)=O GWHCXVQVJPWHRF-UHFFFAOYSA-N 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
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- 239000003814 drug Substances 0.000 description 1
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- 239000012530 fluid Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- ZEMPKEQAKRGZGQ-XOQCFJPHSA-N glycerol triricinoleate Natural products CCCCCC[C@@H](O)CC=CCCCCCCCC(=O)OC[C@@H](COC(=O)CCCCCCCC=CC[C@@H](O)CCCCCC)OC(=O)CCCCCCCC=CC[C@H](O)CCCCCC ZEMPKEQAKRGZGQ-XOQCFJPHSA-N 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
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- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
- C07C51/44—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
- B01D3/322—Reboiler specifications
-
- 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
- Y02P20/10—Process efficiency
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Crystallography & Structural Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to a method and a device for extracting high-purity heptanoic acid from a side line of a vacuum batch rectification, wherein a crude heptanoic acid raw material is fed into a tower kettle of a batch rectification tower, a primary total reflux operation is firstly carried out, then a part of light components and transition fractions are extracted by adopting a variable reflux ratio, and the rest part of light components and transition fractions are refluxed into the tower, then a secondary total reflux operation is continuously carried out, then a stream is extracted from the side line of the batch rectification tower, and a recooler is used for cooling, so that a high-purity heptanoic acid product is obtained. Compared with the prior art, the method can obtain the high-purity heptanoic acid product with the mass fraction of more than 99.4 percent on the basis of reaching the industrial productivity and having a large operation one-way range.
Description
Technical Field
The invention belongs to the technical field of high-purity heptanoic acid rectification separation, and relates to a method and a device for extracting high-purity heptanoic acid from a vacuum batch rectification side line.
Background
Heptanoic acid, also known as nervonic acid, has a boiling point of 223 ℃ at normal pressure and a melting point of-10.5 ℃, is a colorless oily liquid, has a fatty odor and is an important organic synthetic intermediate with malodor when impure, is used as a synthetic raw material for perfumes, medicines, lubricants and plasticizers, is slightly soluble in water, and is soluble in ethanol and diethyl ether. During the synthesis process, heptylene-1 and synthetic gas are first carbonylated to produce heptylaldehyde, and the heptylic acid is then air oxidized to produce heptanoic acid. Firstly, feeding 1-heptylene synthesis gas (carbon monoxide and hydrogen), circulating gas and catalyst solution into a carbonylation reactor, controlling the temperature to be 94-150 ℃ and the pressure to be 1.30 MPa; the aldehyde is separated from the reaction product by decompression flash evaporation, and the catalyst and heavy components can be recycled. The aldehydes are then fed to a reactor for chemical book oxidation and oxidized in air at a pressure of less than 0.69MPa in a mixed transition metal catalyst system. Wherein the aldehyde is converted almost completely and, therefore, no separation and recycling is required. Removing trace catalyst from the product, sending into a double-tower rectification system, removing heavy components (as fuel) in the first tower, and sending the tower top material into the second tower to obtain the finished product branched acid. Or the high temperature cracking of castor oil or the derivative can generate heptaldehyde, and then the heptaldehyde can be oxidized to obtain the heptanoic acid.
During the synthesis reaction, some by-product impurities are produced, such as impurities of caproic acid, caprylic acid and the like. At present, the purity of the heptanoic acid in domestic markets is about 98 percent generally, and the purity of the heptanoic acid in domestic markets can reach 99 percent in a few cases, but the quality of the product is unstable. In some high-end downstream applications, the purity requirement on the heptanoic acid is high, the purity of the heptanoic acid must reach more than 99%, and the higher the content is, the more expensive the price is, the export standard can be reached. In a system for generating the heptanoic acid mixture through the reaction, due to the existence of byproduct impurities such as light components, heavy components and the like, certain difficulty is brought to the purification of the heptanoic acid, and particularly, in the separation process, the octanoic acid is always extracted along with a product at the top of the tower, so that substances such as the octanoic acid and the like exist in the process of extracting the heptanoic acid at the top of the tower, and the purity of the heptanoic acid is influenced. Most of the existing purification processes adopted by the heptanoic acid are common vacuum batch rectification, the purity of the heptanoic acid is not high enough, the yield of the heptanoic acid is reduced, and some of the heptanoic acid with high purity contains octanoic acid and other products with high heavy components, and the products need to be returned to a tower for secondary rectification, so that the energy consumption and the operation time are greatly increased.
Disclosure of Invention
The invention aims to provide a method and a device for extracting high-purity heptanoic acid from a side line by vacuum batch rectification, which can further improve the purity of the heptanoic acid and reduce the content of octanoic acid impurities and the like.
The purpose of the invention can be realized by the following technical scheme:
one of the technical schemes of the invention provides a method for extracting high-purity heptanoic acid from a side line of vacuum batch rectification, which comprises the steps of feeding a crude heptanoic acid raw material into a tower kettle of a batch rectification tower, carrying out primary total reflux operation, extracting part of light components and transition fractions by adopting a variable reflux ratio, refluxing the rest of the light components and the transition fractions into the tower, continuing secondary total reflux operation, extracting a stream from the side line of the batch rectification tower, and cooling by a recooler to obtain a high-purity heptanoic acid product.
Further, the operation pressure of the top of the batch distillation tower is controlled to be 2-10kPa.A, preferably 2-5 kPa.A, and the heating temperature of the tower kettle is controlled to be 100-200 ℃, preferably 140-165 ℃.
Further, the tower top temperature in the first total reflux operation is maintained at 50-150 ℃, preferably 76.6-138 ℃, and the time of the first total reflux is 1 hr.
Furthermore, the change reflux ratio is changed within the range of 1: 1-25: 1, preferably 2: 1-15: 1.
Furthermore, the extraction ratio of the light components to the transition fraction is 40-46%.
Furthermore, the number of theoretical plates extracted from the side of the batch distillation column is 5-35 from top to bottom, and preferably 5-15.
Further, the tower top temperature in the second total reflux operation is 129-131 ℃ for 1 hr.
Further, during side extraction, the top temperature of the batch distillation tower is maintained at 130-140 ℃, preferably 138-140 ℃, and the temperature of the side extraction position is maintained at 135-145 ℃, preferably 140-142 ℃.
Furthermore, the temperature of the refrigerant of the recooler is-10 to 0 ℃, and preferably-5 to 0 ℃.
Further, the crude heptanoic acid raw material comprises butyric acid, acetonitrile, valeric acid, caproic acid, heptanoic acid and caprylic acid.
Furthermore, the intermittent rectifying tower is internally provided with efficient separation packing and a distributor, the efficient separation packing comprises plate corrugations, mesh grid packing, pulse packing, a plate net, silk screen regular packing or efficient regular packing, and the distributor comprises a tubular distributor, a trough tray distributor and the like.
Further, a conventional reboiler is adopted by the batch distillation tower reboiler to provide steam; the condenser at the top of the intermittent rectifying tower adopts a normal-temperature water cooling mode, and the recooler adopts a low-temperature water or low-temperature glycol cooling mode.
Furthermore, the pipeline for conveying the fluid adopts a winding high-temperature heat tracing band, heat preservation cotton or jacket steam for heat preservation.
The second technical scheme of the invention provides a device for vacuum batch distillation side-draw high-purity heptanoic acid, which is used for implementing the method, and comprises a batch distillation tower, a raw material tank, a reboiler, a circulating pump, a condenser, a recooler and a plurality of product tanks, wherein the raw material tank is connected with a batch distillation tower kettle through a feed pump, the reboiler is connected with the circulating pump in series and connected with the batch distillation tower kettle to form circulation, a gas phase outlet at the top of the batch distillation tower is connected with the condenser, two branches are led out from a condensate outlet of the condenser, one branch is connected with at least one product tank, the other branch is returned to the top of the batch distillation tower, and a side-draw branch is further arranged on the batch distillation tower and is sequentially connected with the recooler and the rest product tanks.
Compared with the prior art, the invention can obtain the high-purity heptanoic acid product with the mass fraction of more than 99.4 percent by the method through the side line extraction and product re-cooling device of the vacuum batch distillation tower on the basis of reaching the industrial capacity and having a large operation single-file range. Compared with the traditional process for producing the heptanoic acid, the purity of the product is improved by 0.5-1.5%, the content of the octanoic acid impurity in the product is reduced by 90-95%, the product can be sold as a high-end export product, the recovery rate of the product is improved by 10-15%, and the product has extremely high economic value. The process and the device have the advantages of stable process operation, stable product quality and high recovery rate.
Drawings
FIG. 1 is a process flow diagram of the present invention for purifying heptanoic acid;
FIG. 2 is a flow chart showing the process for purifying heptanoic acid by batch distillation in comparative example 1;
the notation in the figure is:
v101-stock tank; v102-product tank one; v103-product tank II; v104-product tank three; p101-charge pump; p102-circulating pump; t101-batch rectifying tower; e101-a reboiler; e102-a condenser; e103-recooler.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
In the following examples, the batch fractionating tower is filled with efficient separating filler and distributor, wherein the efficient separating filler is silk screen structured filler, and the distributor is common trough tray distributor. Otherwise, unless otherwise specified, all the conventional commercial raw materials or conventional processing techniques are used in the art.
Example 1
The flow chart of the method of the invention is shown in figure 1, and the crude heptanoic acid raw material comprises 0.62 wt% of butyric acid, 1.2 wt% of acetonitrile, 0.2 wt% of valeric acid, 18 wt% of caproic acid, 76.1 wt% of heptanoic acid and 3.88 wt% of caprylic acid. Raw materials are conveyed to a tower bottom of a batch rectification tower T101 from a raw material tank V101 at one time through a feed pump P101P101, cooling water passes through a condenser E102, a refrigerant of 8 ℃ below zero is introduced into a recooler E103, the pressure of the top of the batch rectification tower T101 is 2.25kPa.A, tower bottom raw material liquid circulates in the batch rectification tower T101 through a circulating pump P102, the tower bottom raw material liquid is heated through a reboiler E101 at 155 ℃, the circulating material is partially vaporized and ascended to the top of the tower, heat and mass transfer are carried out between the inside of the whole reflux tower and the ascended vapor phase after being condensed through the condenser E102, namely, the whole reflux is carried out at the beginning of operation, the temperature of the top of the tower is stabilized at 75-75.5 ℃ during the whole reflux, the whole reflux is partially extracted after 1hr, the reflux ratio of a light component extraction stage and a transition fraction extraction stage is set to be 10:1, and 42 percent of the light component and the transition fraction are extracted and enter a product tank V102. And then, carrying out secondary total reflux, wherein the tower top temperature is stabilized at 130-131 ℃ during the total reflux, finally carrying out side line extraction, wherein the side line extraction position is 10 theoretical plates (from top to bottom), the extraction temperature is maintained at 136-142 ℃, the tower top temperature is controlled at 132-134 ℃, and then crystallizing easily-crystallized heavy components such as caprylic acid and the like in the side line extraction position through a secondary cooler E103 to obtain high-purity heptanoic acid, and sending the high-purity heptanoic acid into a product tank II V103 and a product tank III V104. After side line extraction and re-cooling by a re-cooler E103, the purity of the product heptanoic acid is more than 99.47%, the recovery rate of qualified products is 43%, the content of octanoic acid impurities is less than 0.001% (no peak is detected by a chromatogram), and the single-kettle operation time is 98 hr.
Table 1 shows the results of the chromatographic analyses of the products of example 1
TABLE 1
| Serial number | Name (R) | Content/wt% |
| 1 | Paracetone | 0.0332 |
| 2 | Valeric acid | 0.3134 |
| 3 | Hexanoic acid | 0.1834 |
| 4 | Heptanoic acid | 99.47 |
Example 2
Referring to the flow chart of the method of the invention also in figure 1, the crude heptanoic acid raw material comprises 0.22 wt% of butyric acid, 1.4 wt% of acetonitrile, 0.1 wt% of valeric acid, 16 wt% of hexanoic acid, 78.1 wt% of heptanoic acid and 3.98 wt% of octanoic acid. Introducing a refrigerant into a recooler E103, leading the pressure at the top of an intermittent rectifying tower T101 to be 3.325kPa.A, heating the material to be 165 ℃, leading the circulating material to be partially vaporized and risen to the top of the tower, condensing the circulating material by a condenser E102, and then carrying out heat transfer and mass transfer with the rising vapor phase in all reflux towers, namely carrying out total reflux when the operation is started, stabilizing the temperature at the top of the tower at 76-76.8 ℃ when the total reflux is carried out, carrying out the total reflux for 1hr, then carrying out partial extraction, setting the reflux ratio of light components and a transitional fraction extraction stage to be 8:1, extracting 45% of light components and transitional fraction to enter a product tank with a voltage of V102, then carrying out secondary total reflux, stabilizing the temperature at the top of the tower at 129.8-131 ℃ when the total reflux is carried out, and finally extracting the side line, wherein the side line extraction position is 12 theoretical plates (from top to bottom), extracting the side line, the side line extraction temperature is maintained at 138-145 ℃, the temperature at the top of the tower is controlled at 136-140 ℃, then, the heavy components which are easy to crystallize, such as octanoic acid, in the product are crystallized by a recooler E103, and high-purity heptanoic acid is obtained. After side line extraction and re-cooling by a re-cooler E103, the purity of the product heptanoic acid is more than 99.4%, the recovery rate of qualified products is 41%, the content of octanoic acid impurities is 0.05%, and the single-kettle operation time is 95 hr.
Example 3:
the flow chart of the method of the invention is shown in figure 1, and the crude heptanoic acid raw material comprises 0.32 wt% of butyric acid, 1.4 wt% of acetonitrile, 0.1 wt% of valeric acid, 15 wt% of caproic acid, 79.1 wt% of heptanoic acid and 3.88 wt% of caprylic acid. Introducing a refrigerant into the recooler at-4 ℃, the top pressure of the batch distillation tower at 3kPa.A, the heating temperature at 163 ℃, the circulating material partially vaporized and ascended to the top of the tower, condensing the circulating material by a condenser, and then carrying out heat transfer and mass transfer with the ascending vapor phase in the total reflux tower, namely carrying out total reflux when the operation is started, wherein the temperature of the top of the tower is stabilized at 76.9-77.8 ℃ during the total reflux, then carrying out partial extraction after the total reflux is carried out for 1hr, the reflux ratio of the light components and the transition fraction extraction stage is set to be 9:1, extracting 43 percent of the light components and the transition fraction into a product tank 1, then carrying out secondary total reflux, wherein the temperature of the top of the tower is stabilized at 129-, and then crystallizing easily crystallized heavy components such as caprylic acid and the like in the solution by a recooler to obtain high-purity heptanoic acid. After side line extraction and re-cooling by a re-cooler, the product heptanoic acid has purity of above 99.43%, the qualified product recovery rate is 45%, the octanoic acid impurity content is 0.04%, and the single-kettle operation time is 93 hr.
Comparative example 1
Comparative example process flow diagram referring to fig. 2, the starting material composition is 0.4 wt% butyric acid, 1.1 wt% acetonitrile, 0.3 wt% valeric acid, 14 wt% caproic acid, 79.22 wt% heptanoic acid, and 4.98 wt% octanoic acid, and the optimum operating conditions are as follows: the raw materials are pumped into a tower kettle of an intermittent rectifying tower T101 at one time through a feed pump P101, a circulating pump P102 of the tower kettle circulates feed liquid, the feed liquid is vaporized after being heated, a vapor phase is extracted from the top of the tower and condensed, a part of condensed liquid flows back, a part of condensed liquid is extracted, all products are extracted from the top of the tower, and the products are not extracted from the tower kettle. The batch rectification process is set to 3 stages, namely a light component stage, a transition fraction stage and a product stage. The operating parameters are respectively light component stage: the pressure at the top of the tower is 3kPa.A, the reflux ratio is 3, and the number of theoretical plates is 60; a transition fraction stage: the pressure at the top of the tower is 3kPa.A, the reflux ratio is 10, and the number of theoretical plates is 60; and (3) a product stage: the overhead pressure was 5kPa.A, the reflux ratio was 4, and the number of theoretical plates was 60. After the batch rectification operation, the purity of the product heptanoic acid is 98.5%, the recovery rate of qualified products is 30%, the content of octanoic acid impurities is 0.5%, and the single-kettle operation time is 130 hr.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.
Claims (10)
1. A method for extracting high-purity heptanoic acid from a side line of a vacuum batch rectification is characterized in that a crude heptanoic acid raw material is fed into a tower kettle of a batch rectification tower, first total reflux operation is carried out, then a part of light components and transition fractions are extracted by adopting a variable reflux ratio, the rest of light components and transition fractions are refluxed into the tower, then secondary total reflux operation is continuously carried out, then a stream is extracted from the side line of the batch rectification tower, and a recooler is used for cooling, so that a high-purity heptanoic acid product is obtained.
2. The method for extracting high-purity heptanoic acid from side line of vacuum batch distillation as claimed in claim 1, wherein the operation pressure at the top of the batch distillation column is controlled to be 2-10kPa.A, and the heating temperature at the bottom of the column is controlled to be 100-200 ℃.
3. The method for extracting high-purity heptanoic acid from the side of vacuum batch rectification according to claim 1, wherein the overhead temperature during the first total reflux operation is maintained at 50-150 ℃ and the time of the first total reflux is 1 hr.
4. The method for high-purity heptanoic acid by side line extraction through vacuum batch rectification as claimed in claim 1, wherein the variation range of the conversion reflux ratio is 1: 1-25: 1;
the extraction ratio of the light components to the transition fraction is 40-46%.
5. The method for high-purity heptanoic acid by side line extraction through vacuum batch distillation as claimed in claim 1, wherein the number of side line extraction theoretical plates of the batch distillation column is 5-35 from top to bottom.
6. The method for high-purity heptanoic acid by side line distillation in vacuum batch distillation as claimed in claim 1, wherein the overhead temperature of the secondary total reflux operation is 129-131 ℃ for 1 hr.
7. The method for high-purity heptanoic acid by side line extraction through vacuum batch distillation as claimed in claim 1, wherein the top temperature of the batch distillation column is maintained at 130-140 ℃ and the temperature of the side line extraction position is maintained at 135-145 ℃.
8. The method for high-purity heptanoic acid by side line distillation in vacuum batch distillation as claimed in claim 1, wherein the refrigerant temperature of the recooler is-10 to 0 ℃.
9. The method for high-purity heptanoic acid by vacuum batch distillation side line extraction is characterized in that the crude heptanoic acid raw material comprises butyric acid, acetonitrile, valeric acid, caproic acid, heptanoic acid and octanoic acid.
10. A device for side-drawing high-purity heptanoic acid by vacuum batch distillation, which is used for implementing the method as claimed in any one of claims 1 to 9, and is characterized by comprising a batch distillation tower, a raw material tank, a reboiler, a circulating pump, a condenser, a recooler and a plurality of product tanks, wherein the raw material tank is connected with a batch distillation tower kettle through a feed pump, the reboiler is connected with the circulating pump in series and connected with the batch distillation tower kettle to form a cycle, a gas phase outlet at the top of the batch distillation tower is connected with the condenser, a condensate outlet of the condenser leads out two branches, one branch is connected with at least one product tank, the other branch is connected with the top of the batch distillation tower in a returning way, and a side-drawing branch is further arranged on the batch distillation tower and is sequentially connected with the recooler and the rest product tanks.
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| CN202210100163.1A CN114394894B (en) | 2022-01-27 | 2022-01-27 | Method and device for extracting Gao Chungeng acid from side line of vacuum batch distillation |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102329186A (en) * | 2011-07-25 | 2012-01-25 | 天津市泰旭物流有限公司 | Method for preparing high-purity 1,2-butadiene by batch rectification method of ice water condensation |
| CN105418430A (en) * | 2015-12-16 | 2016-03-23 | 东营市海科新源化工有限责任公司 | Device and method for preparing high-purity dimethyl carbonate through batch rectification |
| CN110642708A (en) * | 2019-10-31 | 2020-01-03 | 中国农业科学院农业环境与可持续发展研究所 | Method for separating and extracting caproic acid, heptanoic acid and octanoic acid from livestock and poultry manure anaerobic acidification liquid |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102329186A (en) * | 2011-07-25 | 2012-01-25 | 天津市泰旭物流有限公司 | Method for preparing high-purity 1,2-butadiene by batch rectification method of ice water condensation |
| CN105418430A (en) * | 2015-12-16 | 2016-03-23 | 东营市海科新源化工有限责任公司 | Device and method for preparing high-purity dimethyl carbonate through batch rectification |
| CN110642708A (en) * | 2019-10-31 | 2020-01-03 | 中国农业科学院农业环境与可持续发展研究所 | Method for separating and extracting caproic acid, heptanoic acid and octanoic acid from livestock and poultry manure anaerobic acidification liquid |
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