CN114853626A - Method for recovering DMAC (dimethylacetamide) in aramid fiber production byproducts - Google Patents
Method for recovering DMAC (dimethylacetamide) in aramid fiber production byproducts Download PDFInfo
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- CN114853626A CN114853626A CN202210587155.4A CN202210587155A CN114853626A CN 114853626 A CN114853626 A CN 114853626A CN 202210587155 A CN202210587155 A CN 202210587155A CN 114853626 A CN114853626 A CN 114853626A
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- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 title claims abstract description 108
- 238000000034 method Methods 0.000 title claims abstract description 35
- 239000006227 byproduct Substances 0.000 title claims abstract description 17
- 229920006231 aramid fiber Polymers 0.000 title claims abstract description 14
- 238000007380 fibre production Methods 0.000 title claims abstract description 13
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims abstract description 92
- 239000007788 liquid Substances 0.000 claims abstract description 71
- 235000019270 ammonium chloride Nutrition 0.000 claims abstract description 46
- 239000013078 crystal Substances 0.000 claims abstract description 45
- 238000003860 storage Methods 0.000 claims abstract description 38
- 238000000746 purification Methods 0.000 claims abstract description 34
- 238000001914 filtration Methods 0.000 claims abstract description 22
- 238000001704 evaporation Methods 0.000 claims abstract description 15
- 238000009833 condensation Methods 0.000 claims abstract description 11
- 230000005494 condensation Effects 0.000 claims abstract description 11
- 230000008020 evaporation Effects 0.000 claims abstract description 10
- 238000003756 stirring Methods 0.000 claims description 21
- 239000012535 impurity Substances 0.000 claims description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 15
- 238000001514 detection method Methods 0.000 claims description 14
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 239000000047 product Substances 0.000 claims description 7
- 229910052799 carbon Inorganic materials 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 5
- 238000009826 distribution Methods 0.000 claims description 4
- 230000000694 effects Effects 0.000 claims description 3
- 238000001228 spectrum Methods 0.000 claims description 3
- 239000004760 aramid Substances 0.000 claims 6
- 229920003235 aromatic polyamide Polymers 0.000 claims 6
- 238000011084 recovery Methods 0.000 abstract description 7
- 239000002699 waste material Substances 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 41
- OHLUUHNLEMFGTQ-UHFFFAOYSA-N N-methylacetamide Chemical compound CNC(C)=O OHLUUHNLEMFGTQ-UHFFFAOYSA-N 0.000 description 13
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 230000036760 body temperature Effects 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000002798 polar solvent Substances 0.000 description 2
- 238000013094 purity test Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229920002994 synthetic fiber Polymers 0.000 description 2
- 239000012209 synthetic fiber Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- HIXDQWDOVZUNNA-UHFFFAOYSA-N 2-(3,4-dimethoxyphenyl)-5-hydroxy-7-methoxychromen-4-one Chemical compound C=1C(OC)=CC(O)=C(C(C=2)=O)C=1OC=2C1=CC=C(OC)C(OC)=C1 HIXDQWDOVZUNNA-UHFFFAOYSA-N 0.000 description 1
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000001491 aromatic compounds Chemical class 0.000 description 1
- 229960001701 chloroform Drugs 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000005662 electromechanics Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- RTZKZFJDLAIYFH-UHFFFAOYSA-N ether Substances CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000199 molecular distillation Methods 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000003440 toxic substance Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C231/00—Preparation of carboxylic acid amides
- C07C231/22—Separation; Purification; Stabilisation; Use of additives
- C07C231/24—Separation; Purification
-
- 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
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
- Y02P70/62—Manufacturing or production processes characterised by the final manufactured product related technologies for production or treatment of textile or flexible materials or products thereof, including footwear
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a method for recovering DMAC (dimethylacetamide) in aramid fiber production byproducts, which particularly relates to the technical field of aramid fiber production and specifically comprises the following steps: filtering the ammonium chloride crystals, and carrying out the second step: and (5) reduced pressure evaporation, step three: and (5) filtering, and step four: condensation, step five: storage, step six: and (5) purifying. According to the invention, through reduced pressure evaporation, the dimethylacetamide liquid is separated from the ammonium chloride crystal, and the separated dimethylacetamide gas is subjected to operations such as filtration and condensation, so that gaseous dimethylacetamide is condensed into liquid again, and meanwhile, the purity of the dimethylacetamide liquid is improved through a circulating purification mode of a rectifying tower, so that the high-purity recovery of the dimethylacetamide liquid is achieved, and the waste of dimethylacetamide liquid in the ammonium chloride crystal is reduced.
Description
Technical Field
The invention relates to the technical field of aramid fiber production, in particular to a method for recovering DMAC (dimethylacetamide) in aramid fiber production byproducts.
Background
Aramid fiber is a material made of novel high-tech synthetic fiber, has excellent performances of ultrahigh strength, high modulus, high temperature resistance, acid and alkali resistance, light weight and the like, and is widely applied to various aspects of national economy such as aerospace, electromechanics, buildings, automobiles, sports goods and the like;
dimethylacetamide is a colorless transparent liquid which is commonly used as an aprotic polar solvent, is flammable, can be randomly mixed with organic solvents such as water, alcohol, ether, ester, benzene, trichloromethane, aromatic compounds and the like, and is commonly used as a raw material for synthetic fibers and an excellent polar solvent for organic synthesis;
ammonium chloride is an inorganic substance, is a byproduct in the alkali manufacturing industry, contains 24-26% of nitrogen, is white or slightly yellowish square or octahedral small crystal, has powder and granular formulations, and is difficult to absorb moisture and easy to store.
In the aramid fiber production process, dimethylacetamide is often used as a solvent, ammonium chloride crystals are generated during a neutralization reaction, part of dimethylacetamide remains in ammonium chloride (the humidity is about 30% -45%) during filtration, and in order to avoid dimethylacetamide waste or cause environmental pollution due to emission, dimethylacetamide-containing liquid in the ammonium chloride crystals needs to be recovered to achieve the purpose of reuse, the invention provides a DMAC (dimethylacetamide) recovery method in aramid fiber production byproducts, which can separate dimethylacetamide in the ammonium chloride crystals and improve the recovery concentration of dimethylacetamide;
at present, no relevant technology and method are disclosed for recovering dimethylacetamide liquid in the interior of ammonium chloride crystals.
Disclosure of Invention
In order to overcome the above defects in the prior art, embodiments of the present invention provide a method for recovering DMAC from an aramid fiber production byproduct, wherein the method comprises performing reduced pressure evaporation separation on methylacetamide and ammonium chloride crystals, re-condensing the separated gas into a liquid by filtration, condensation, and the like, and finally achieving high purity recovery of dimethylacetamide liquid by a cyclic rectification purification method, so as to solve the above problems in the background art.
In order to achieve the purpose, the invention provides the following technical scheme: a method for recovering DMAC (dimethylacetamide) in aramid fiber production byproducts specifically comprises the following steps:
the method comprises the following steps: filtering the ammonium chloride crystal to remove solid impurities in the ammonium chloride crystal and improve the original purity of the ammonium chloride crystal;
step two: filtering ammonium chloride crystal, and evaporating 600kg of ammonium chloride crystal containing dimethylacetamide liquid in a stirring tank under reduced pressure, wherein the pressure is controlled to be-90 kpa-70 kpa, and the steam pressure is 0.3kpa-0.4 kpa;
step three: in the second step, after the ammonium chloride crystal containing the dimethylacetamide liquid in the stirring tank is subjected to reduced pressure evaporation, dimethylacetamide and the ammonium chloride crystal are separated, so that the evaporated dimethylacetamide gas enters the filter through the gas phase pipe to be filtered;
step four: filtering the mixed gas and impurities in the dimethylacetamide gas through a filter, conveying the filtered mixed gas and impurities into a condenser through a gas phase pipe, and performing condensation liquefaction treatment to re-condense the dimethylacetamide gas into a liquid state;
step five: conveying the liquefied dimethylacetamide to the interior of a storage tank for storage, wherein the storage environment is vacuum storage;
step six: the dimethylacetamide liquid inside the storage tank is conveyed to the interior of the rectifying tower through the vacuum pump for purification treatment, the dimethylacetamide liquid enters the rectifying tower and is distributed through the distribution disc after flowing down along the tower wall, a material film is formed through a film scraper, in the downward flowing process, light component gas is evaporated, and is filtered and liquefied through a gas phase tube and enters a filter and a condenser again, and enters the interior secondary purification of the rectifying tower again, heavy component liquid enters the storage tank for storage, and the storage tank is filled with finished products with high purity.
In a preferred embodiment, in the fourth step, the bottom of the inner cavity of the condenser contains activated carbon, the condensed dimethylacetamide slowly drops on the surface of the activated carbon, and the condensed liquid is filtered and purified by the activated carbon.
In a preferred embodiment, the condenser temperature after the first condensation in step four is from-180 ℃ to-200 ℃, and the condenser temperature after the second condensation in step six is from-195 ℃ to 220 ℃.
In a preferred embodiment, in the sixth step, in the first purification process of the rectifying tower, the temperature of the rectifying tower body is 115-130 ℃, and the vacuum degree is 50-80 mmHg, and in the second purification process of the rectifying tower, the temperature of the rectifying tower body is 130-150 ℃, and the vacuum degree is 4-6 kpa.
In a preferred embodiment, in the second step, the stirring tank is a jacketed stirring tank, the temperature of the stirring tank is in the range of 160 ℃ and 175 ℃, and the stirring speed is 80 rpm.
In a preferred embodiment, in the sixth step, the dimethylacetamide liquid after the primary purification and the multiple purifications is mixed and subjected to purity detection, and if the purity is not up to the standard, the dimethylacetamide liquid is repeatedly purified again through the rectifying tower.
In a preferred embodiment, the purity detection mode is one activity of instrumental detection and color spectrum detection, and the detection purity is greater than or equal to 95%.
The invention has the technical effects and advantages that:
1. the method comprises the steps of filtering ammonium chloride crystals to remove solid impurities in the ammonium chloride crystals, improving the purity of original ammonium chloride crystals, placing the ammonium chloride crystals containing dimethylacetamide liquid in a stirring tank for reduced pressure evaporation, evaporating the ammonium chloride crystals and dimethylacetamide under low pressure to enable dimethylacethyl to generate steam and conveying the steam to a filter for filtration, simultaneously, feeding filtered dimethylacethyl gas into a condenser for condensation operation to enable the dimethylacethyl gas to be condensed into liquid again, recovering the dimethylacethyl in the ammonium chloride crystals, and finally purifying the extracted dimethylacethyl liquid through a rectifying tower;
2. through a circulating rectification purification mode, firstly, the dimethylacetamide liquid entering the rectification tower for the first time is purified, so that the light component gas is discharged from the tower top, the heavy component gas is discharged from the tower bottom and is stored through a storage tank, the light component gas discharged from the tower top is filtered and condensed again to enter the rectification tower for purification again, the circulating flow of the dimethylacetamide liquid is realized, the dimethylacetamide liquid purity is further improved, the liquid after multiple purifications is mixed and then is subjected to purity detection, the purity of the extracted dimethylacetamide liquid can reach the qualified standard, the generation of dimethylacetamide liquid with low purity is reduced, and when the dimethylacetamide gas is condensed, a small amount of toxic substances and impurities contained in the gas are filtered by using activated carbon, and the steps of circulating purification are reduced, the recovery efficiency of the dimethylacetamide liquid is improved.
Drawings
FIG. 1 is a flow chart of the method of example 1 of the present invention.
FIG. 2 is a flowchart of a method of embodiment 2 of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
Embodiment 1, a method for recovering DMAC from aramid fiber production byproducts, specifically comprising the following steps:
the method comprises the following steps: filtering the ammonium chloride crystal to remove solid impurities in the ammonium chloride crystal and improve the original purity of the ammonium chloride crystal;
step two: after filtering the ammonium chloride crystal, placing 600kg of the ammonium chloride crystal containing the dimethylacetamide liquid in a stirring tank with a jacket for reduced pressure evaporation, wherein the pressure is controlled at-85 kpa, the steam pressure is 0.35kpa, the temperature of the stirring tank is within 165 ℃, and the stirring speed is 80 revolutions per minute;
step three: in the second step, after the ammonium chloride crystal containing the dimethylacetamide liquid in the stirring tank is subjected to reduced pressure evaporation, dimethylacetamide and the ammonium chloride crystal are separated, so that the evaporated dimethylacetamide gas enters the filter through the gas phase pipe to be filtered;
step four: filtering mixed gas and impurities in the dimethylacetamide gas through a filter, conveying the filtered mixed gas and impurities into a condenser at the temperature of-185 ℃ through a gas phase pipe, condensing and liquefying the mixed gas and the impurities to re-condense the dimethylacetamide gas into liquid, and slowly dripping the liquefied dimethylacetamide on the surface of activated carbon to perform filtration and purification;
step five: conveying the liquefied dimethylacetamide to the interior of a storage tank for storage, wherein the storage environment is vacuum storage, and the dimethylacetamide liquid in the storage tank is not high in purity;
step six: the method comprises the following steps of conveying dimethylacetamide liquid with low purity in a storage tank to the interior of a rectifying tower with the tower body temperature of 120 ℃ and the vacuum temperature of 60mmHg through a vacuum pump for purification treatment, distributing the dimethylacetamide liquid through a distribution disc after entering the rectifying tower, flowing down along the tower wall, forming a material film through a film scraper, evaporating light component gas in the downward flowing process, re-entering a filter through a gas phase pipe, entering heavy component liquid into the storage tank for storage, and performing primary purification on the dimethylacetamide liquid in the storage tank;
the primarily purified light component gas enters the filter again through the gas phase pipe to be filtered, then is conveyed to a condenser containing active carbon to be condensed and filtered, and enters the rectifying tower again to be secondarily rectified and purified, wherein the temperature of the condenser is-200 ℃, the temperature of the rectifying tower body is 140 ℃, the vacuum degree is 4.5kpa, and the secondary purification is carried out;
and mixing the dimethylacetamide liquid after the first purification and the dimethylacetamide liquid after the second purification, and performing purity test, wherein the test standard is that the purity is not less than 95%, and once the purity does not reach the standard, repeatedly purifying by passing through a rectifying tower again.
In this embodiment, firstly, the ammonium chloride crystal containing the methylacetamide liquid is evaporated under reduced pressure, the methylacetamide liquid and the ammonium chloride crystal are separated, and the gaseous methylacetamide is filtered and condensed, so that the gaseous methylacetamide is liquefied again after being filtered, at this time, the methylacetamide liquid with low purity is obtained, the liquid with low purity is purified by a rectifying tower, in the purification process, the light component enters a filter and a condenser again for filtering and condensing, the heavy component enters a storage tank for storage, the methylacetamide liquid purified for the first time is obtained, the light component methylacetamide filtered and condensed again enters the rectifying tower again for purification, the methylacetamide liquid purified for the second time is obtained, the methylacetamide liquids purified for the first time and the second time are mixed, and then the instrument is used for detection and the hue spectrum detection are performed, and detecting the purity of the product until the purity reaches not less than 95 percent to obtain a qualified product, and if the product does not reach the standard, repeatedly purifying the product by using a rectifying tower, wherein the purity reaches 98 percent after detection, and the product is colorless and transparent.
Embodiment 2, a method for recovering DMAC from aramid fiber production byproducts, specifically comprising the following steps:
the method comprises the following steps: filtering the ammonium chloride crystal to remove solid impurities in the ammonium chloride crystal and improve the original purity of the ammonium chloride crystal;
step two: filtering ammonium chloride crystals, and placing 600kg of ammonium chloride crystals containing dimethylacetamide liquid in a jacketed stirring tank for reduced pressure evaporation, wherein the pressure is controlled at-80 kpa, the steam pressure is 0.35kpa, the temperature of the stirring tank is within the range of 170 ℃, and the stirring speed is 80 revolutions per minute;
step three: in the second step, after the ammonium chloride crystal containing the dimethylacetamide liquid in the stirring tank is subjected to reduced pressure evaporation, dimethylacetamide and the ammonium chloride crystal are separated, so that the evaporated dimethylacetamide gas enters the filter through the gas phase pipe to be filtered;
step four: filtering mixed gas and impurities in the dimethylacetamide gas through a filter, conveying the mixed gas and the impurities into a condenser at the temperature of-190 ℃ through a gas phase pipe, condensing and liquefying the mixed gas and the impurities to enable the dimethylacetamide gas to be condensed into liquid again, slowly dropping the liquefied dimethylacetamide on the surface of active carbon to perform filtration and purification, and removing the impurities in the liquefied dimethylacetamide;
step five: conveying the liquefied dimethylacetamide into a storage tank for storage, wherein the storage environment is vacuum storage, and the dimethylacetamide liquid in the storage tank has low purity;
step six: the method comprises the following steps of conveying dimethylacetamide liquid with low purity in a storage tank to the interior of a rectifying tower with the tower body temperature of 125 ℃ and the vacuum temperature of 75mmHg through a vacuum pump for purification treatment, distributing the dimethylacetamide liquid through a distribution disc after entering the rectifying tower, flowing down along the tower wall, forming a material film through a film scraper, evaporating light component gas in the downward flowing process, re-entering a condenser through a gas phase pipe, entering heavy component liquid into the storage tank for storage, and performing primary purification on the dimethylacetamide liquid in the storage tank;
the primarily purified light component gas enters the condenser again through the gas phase pipe to be condensed, and enters the rectifying tower again to be rectified and purified for the second time, wherein the temperature of the condenser is-215 ℃, the temperature of the rectifying tower body is 145 ℃, the vacuum degree is 5kpa, and the purification for the second time is carried out;
and mixing the dimethylacetamide liquid after the first purification and the dimethylacetamide liquid after the second purification, and carrying out purity test on the dimethylacetamide liquid, wherein the test standard is that the purity is not less than or equal to 95%, and once the purity does not reach the standard, repeatedly purifying the dimethylacetamide liquid by passing through a high-molecular distillation column again.
In example 2, different from example 1, after the primary purification of the methylacetamide liquid, the light component substances purified by the rectifying tower directly enter the condenser for condensation, and are not filtered by the filter, so that the recovery step of the methylacetamide liquid is simplified on the basis of not changing the purification mode of example 1, the recovery efficiency is improved, the purity of the methylacetamide liquid can reach 96.78%, and the recovered liquid is colorless and transparent.
Secondly, the method comprises the following steps: in the drawings of the disclosed embodiments of the invention, only the structures related to the disclosed embodiments are referred to, other structures can refer to common designs, and the same embodiment and different embodiments of the invention can be combined with each other without conflict;
and finally: the above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that are within the spirit and principle of the present invention are intended to be included in the scope of the present invention.
Claims (7)
1. A method for recovering DMAC (dimethylacetamide) in aramid fiber production byproducts is characterized by comprising the following steps of: the method specifically comprises the following steps:
the method comprises the following steps: filtering the ammonium chloride crystal to remove solid impurities in the ammonium chloride crystal and improve the original purity of the ammonium chloride crystal;
step two: filtering ammonium chloride crystal, and evaporating 600kg of ammonium chloride crystal containing dimethylacetamide liquid in a stirring tank under reduced pressure, wherein the pressure is controlled to be-90 kpa-70 kpa, and the steam pressure is 0.3kpa-0.4 kpa;
step three: in the second step, after the ammonium chloride crystal containing the dimethylacetamide liquid in the stirring tank is subjected to reduced pressure evaporation, dimethylacetamide and the ammonium chloride crystal are separated, so that the evaporated dimethylacetamide gas enters the filter through the gas phase pipe to be filtered;
step four: filtering the mixed gas and impurities in the dimethylacetamide gas through a filter, conveying the filtered mixed gas and impurities into a condenser through a gas phase pipe, and performing condensation liquefaction treatment to re-condense the dimethylacetamide gas into a liquid state;
step five: conveying the liquefied dimethylacetamide to the interior of a storage tank for storage, wherein the storage environment is vacuum storage;
step six: the dimethylacetamide liquid inside the storage tank is conveyed to the interior of the rectifying tower through the vacuum pump for purification treatment, the dimethylacetamide liquid enters the rectifying tower and is distributed through the distribution disc after flowing down along the tower wall, a material film is formed through a film scraper, in the downward flowing process, light component gas is evaporated, and is filtered and liquefied through a gas phase tube and enters a filter and a condenser again, and enters the interior secondary purification of the rectifying tower again, heavy component liquid enters the storage tank for storage, and the storage tank is filled with finished products with high purity.
2. The method for recovering DMAC (dimethylacetamide) in the aramid production byproduct according to claim 1, characterized by comprising the following steps: in the fourth step, the bottom of the inner cavity of the condenser contains active carbon, the condensed dimethylacetamide slowly drops on the surface of the active carbon, and the condensed liquid is filtered and purified through the active carbon.
3. The method for recovering DMAC (dimethylacetamide) in the aramid production byproduct according to claim 1, characterized by comprising the following steps: in the fourth step, the temperature of the condenser after the first condensation is-180 ℃ to-200 ℃, and in the sixth step, the temperature of the condenser after the second condensation is-195 ℃ to 220 ℃.
4. The method for recovering DMAC (dimethylacetamide) in the aramid production byproduct according to claim 1, characterized by comprising the following steps: in the sixth step, the temperature of the rectifying tower body is 115-130 ℃ and the vacuum degree is 50-80 mmHg in the first-step purification process of the rectifying tower, and the temperature of the rectifying tower body is 130-150 ℃ and the vacuum degree is 4-6kpa in the second-step purification process of the rectifying tower.
5. The method for recovering DMAC (dimethylacetamide) in the aramid production byproduct according to claim 1, characterized by comprising the following steps: in the second step, the stirring tank is a jacketed stirring tank, the temperature of the stirring tank is in the range of 160-175 ℃, and the stirring speed is 80 rpm.
6. The method for recovering DMAC (dimethylacetamide) in the aramid production byproduct according to claim 1, characterized by comprising the following steps: and in the sixth step, the dimethylacetamide liquid after the primary purification and the repeated purification is mixed and then subjected to purity detection, and if the purity does not reach the standard, the dimethylacetamide liquid is repeatedly purified again through the rectifying tower.
7. The method for recovering DMAC (dimethylacetamide) in the aramid production byproduct according to claim 6, characterized by comprising the following steps: the purity detection mode is one activity of instrument detection and color spectrum detection, and the detection purity is equal to or larger than 95%.
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| CN106564913A (en) * | 2016-11-04 | 2017-04-19 | 烟台泰和新材料股份有限公司 | Method for producing high-purity ammonium chloride from meta-position aramid by-products |
| CN206304382U (en) * | 2016-12-21 | 2017-07-07 | 四川辉腾科技股份有限公司 | A kind of solvent DMAC vacuum recovering apparatus of aramid fiber production |
| CN107829328A (en) * | 2017-10-25 | 2018-03-23 | 超美斯新材料（淮安）有限公司 | A kind of preparation method of compound type insulating meta-position aramid fiber paper |
| CN110563669A (en) * | 2019-10-09 | 2019-12-13 | 四川鸿鹏新材料有限公司 | Method and device for improving morpholine purity |
| CN111333530A (en) * | 2020-03-11 | 2020-06-26 | 浙江省天正设计工程有限公司 | Heat pump rectification process for recycling DMAC (dimethylacetamide) or DMF (dimethyl formamide) waste liquid |
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