CN101255122A - Method for purifying dimethylacetamide from spinning wastewater - Google Patents
Method for purifying dimethylacetamide from spinning wastewater Download PDFInfo
- Publication number
- CN101255122A CN101255122A CNA2007100377972A CN200710037797A CN101255122A CN 101255122 A CN101255122 A CN 101255122A CN A2007100377972 A CNA2007100377972 A CN A2007100377972A CN 200710037797 A CN200710037797 A CN 200710037797A CN 101255122 A CN101255122 A CN 101255122A
- Authority
- CN
- China
- Prior art keywords
- extraction
- dimethylacetamide
- tower
- purifying
- extraction agent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Extraction Or Liquid Replacement (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to a process for purifying dimethylacetamide from spinning waste water in the production processe of aromatic polyamide fibrous. The process comprises extraction and rectification, wherein the extraction process comprises forming an extract phase composed of extractive agent and dimethylacetamide and a surplus phase composed of salts, water, and the residual extractive agent, by performing mixture, extraction and split phase of extractive agent and spinning waste water in the extraction equipment; and the rectification process comprises introducing the extract phase into rectification equipment, distilling off steam of the extractive agent form the top of a rectification column for recycling as the extractive agent after cooled, and holding dimethylacetamide at the bottom of the rectification column as polymerization raw material after discharged. The process for purifying dimethylacetamide in the spinning waste water greatly reduces the energy consumption of the whole purifying process, and raises the purity of dimethylacetamide obtained by separating.
Description
Technical field
The present invention relates to a kind of production process of aromatic polyamide fibre, particularly a kind of in the production process of aromatic polyamide fibre from filature wastewater the method for purifying dimethylacetamide (DMAc).
Background technology
Prepare in the production process of aromatic polyamide fibre at the solution polymerization wet-spinning that with DMAc is solvent, filature wastewater mainly is made up of water, DMAc, salt three components, and wherein DMAc concentration is 5～30%, and salt concn is 0.5～5%.If not treated direct discharging, contaminate environment not only, and make DMAc can not get reclaiming and wasted resource.
The method of purification DMAc component generally adopts evaporation rectifying separation method from filature wastewater at present: by evaporation the water in the filature wastewater, DMAc are separated with salt.Adopt the high temperature rectification method that the phlegma of water with the DMAc mixed vapour separated then, in rectifying, water vapor steams from cat head, and DMAc stays at the bottom of the tower, the DMAc product after the discharging can be again as the solvent reclaiming of aromatic polyamide fibre solution polymerization.The shortcoming of this method is that twice evaporation has taken place in whole sepn process, and evaporation of water latent heat is higher, and it is huge to consume energy.Salt accumulates on the vaporizer easily in addition, has influenced the heat exchange effect.
Summary of the invention
For addressing the above problem, the invention provides a kind of method that in the aromatic polyamide fibre production process, adopts DMAc in the extraction fractional distillation purification filature wastewater, whole extraction process mixes phase-splitting at normal temperatures, filature wastewater is after extraction, sepn process is separated by twice high temperature of water, salt and DMAc three components of prior art and has become extraction agent and separate with the high temperature of DMAc, thereby avoided the twice evaporation of water, extraction agent only evaporates once in rectifying, reduces the energy input of whole purification process.
For achieving the above object, of the present invention from filature wastewater the method for purifying dimethylacetamide, its technological process comprises extraction and rectifying.
Described extraction process process is: extraction agent and filature wastewater carry out the hybrid extraction phase-splitting in extraction equipment, extraction agent extracts DMAc in the filature wastewater, has formed extraction phase; All the other component water and salt are insoluble with extraction phase, have formed extracting phase.
Described rectification process process is: extraction phase enters rectifying device, and the low boiling component extraction agent steams from liquid phase, and extraction agent steam recycles as extraction agent after cat head discharging condensation; And high boiling component DMAc stays at the bottom of the rectifying tower, can use as the solvent of aromatic polyamide fibre solution polymerization after the discharging.
Of the present invention from filature wastewater the method for purifying dimethylacetamide, its technological process also comprises stripping, described stripping process process is: the extracting phase that contains a small amount of extraction agent enters stripping apparatus, is steam stripping agent with the superheated vapour, stripping goes out extraction agent wherein.Extraction agent steam recycles as extraction agent after discharging condensation from cat head; And brine waste directly discharges at the bottom of the tower.
In extraction process, extraction agent and filature wastewater are according to certain volume flow ratio, enter hybrid extraction in the extraction equipment with reflux type, and both volume flow ratios are 2～10: 3.The extraction equipment of selecting for use is the disclosed multistage tower settler of Chinese patent CN2832260Y.Under this processing requirement, the progression of mixer-settler is 5～20 grades.Filature wastewater from next stage mixer-settler gently mutually inlet enter, extraction agent enters from the heavy liquid inlet of upper level mixer-settler.In the mixing zone, under the stirring action of whipping appts, two solution generation thorough mixing, because the difference of different components solubleness in extraction agent in the filature wastewater, the DMAc component constantly circulates in the extraction agent.Enter settling section through mixture export, mixed solution is divided into two-phase, i.e. extraction phase and extracting phase.Behind counter-current extraction step by step, DMAc enters in the extraction phase substantially, and last extraction phase is discharged by the heavy out of next stage, and extracting phase is discharged by the light phase export of upper level.Extraction phase is made up of extraction agent and DMAc, and wherein DMAc content accounts for 5～20%.Salt and water are insoluble to extraction agent, have formed extracting phase, wherein residual a spot of extraction agent, and DMAc concentration is lower than 300ppm.
In rectifying, the high efficiency separation of extraction agent and DMAc two components realizes by rectifying separation in the extraction phase, adopts material filling type rectifying tower equipment.Rectifying tower is operated under certain negative pressure, the constant arbitrary pressure between 0～50kPa of absolute pressure in the tower.The type of heating of rectifying tower bottoms material is to feed the superheated vapour heat exchange in reboiler, and column bottom temperature remains between 100～150 ℃.The low boiling component extraction agent evaporates in the extraction phase, after extraction agent steam steams condensation from cat head, does not contain DMAc in the phlegma.Partial condensation liquid is back in the rectifying tower, and control of reflux ratio is in 0.01～0.5 scope; All the other recycle as the extraction agent raw material.High boiling component DMAc then stays at the bottom of the rectifying tower, and the DMAc product purity of discharging at the bottom of the tower is very high, and water ratio is lower than 200ppm, and the solvent that can be used as the aromatic polyamide solution polymerization uses.
The extracting phase that contains a small amount of extraction agent component is difficult to direct discharging, adopts vaporizing extract process to handle, and selects material filling type stripping tower equipment for use, is steam stripping agent with the superheated vapo(u)r, recycles after the overhead vapours condensation.Stripping cat head homo(io)thermism is between 85～115 ℃.The concentration of extraction agent is lower than 0.8ppm in the hot wastewater of discharging at the bottom of the stripping tower.The deposition of salt on equipment avoided in the direct discharging of brine waste.
The present invention selects 1 for use, and organic solvents such as 2-ethylene dichloride, trichloromethane are as extraction agent.According to the similar principle that mixes, these selection of Extractant are good, with water, salt indissoluble, and dissolve each other fully with DMAc, and the partition ratio that obtains through single-stage extraction is between 0.3～1.5.Because the effect of single-stage extraction is limited, adopt multi-stage counter current extraction, extraction progression is 5～20 grades, these extraction agents can extract DMAc component in the filature wastewater fully.
The present invention greatly reduces the energy input of whole purification process.Because whole extraction process mixes phase-splitting at normal temperatures, filature wastewater is after extraction, sepn process is separated by twice high temperature of water, salt and DMAc three components of present technology and has become extraction agent and separate with the high temperature of DMAc, thereby avoided the twice evaporation of water, extraction agent only evaporates once in rectifying, and the vaporization heat of part extraction agent is 250kcal/kg, and far below evaporation of water latent heat 2256kcal/kg, whole purification process power consumption is low.
The present invention has improved the purity of separating the DMAc product that obtains, and the boiling point difference of the boiling point of extraction agent and DMAc is big, and the boiling point of these extraction agents is lower than 90 ℃, far below 160 ℃ of the boiling points of DMAc, helps two components and separates more thoroughly in rectifying.
In the method for extraction fractional distillation purification DMAc of the present invention, the extraction agent in extraction phase and the extracting phase all recycles, and effect of extracting is constant, and whole purification process does not almost have consumption.
Embodiment
The part and the percentage ratio that relate in the following example except that specified otherwise is arranged, are weight part.
Embodiment 1:
With the trichloromethane is extraction agent, and 1 part of filature wastewater and 1 part of extraction agent that contains 5%DMAc is quantitatively sent into multistage tower clarifying tank simultaneously, and the extraction of 15 stage countercurrents takes place under stirring action mixing solutions.Extraction agent extracts the whole DMAc in the filature wastewater, and the extraction phase of formation is made up of trichloromethane and DMAc; Extracting phase mainly is made up of salt and water, contains a spot of trichloromethane.Extraction phase enters rectifying tower after discharging from tower clarifying tank bottom, and absolute pressure is constant in 50kPa in the rectifying tower, and column bottom temperature is constant in 150 ℃, and the control of reflux ratio of overhead condensation liquid is 0.5, and trichloromethane with DMAc takes place accurate the separation.The DMAc product that obtains through rectifying separation at the bottom of the tower, water ratio is lower than 200ppm, recycles as extraction agent behind the cat head trichloromethane vapour condensation.After extracting phase is discharged from tower clarifying tank top, enter stripping tower, feed the superheated vapour stripping and go out a spot of trichloromethane in the extracting phase, recycle as extraction agent behind the trichloromethane vapour condensation, the concentration of trichloromethane is lower than 0.8ppm in the waste water of discharging at the bottom of the stripping tower.In the whole recovery process, the rate of recovery of DMAc is high in the filature wastewater, reaches 99.1%.The DMAc based on very high purity of discharging at the bottom of the tower can be used for the solution polymerization wet-spinning of aromatic polyamide fibre.
Embodiment 2:
With the trichloromethane is extraction agent, and 1 part of filature wastewater and 1.5 parts of extraction agent that contain 15%DMAc is quantitatively sent into multistage tower clarifying tank simultaneously, and the extraction of 20 stage countercurrents takes place under stirring action mixing solutions.Extraction agent extracts the whole DMAc in the filature wastewater, and the extraction phase of formation is made up of trichloromethane and DMAc; Extracting phase mainly is made up of salt and water, contains a spot of trichloromethane.Extraction phase enters rectifying tower after discharging from multistage tower clarifying tank bottom, and absolute pressure is constant in 20kPa in the rectifying tower, and column bottom temperature is constant in 120 ℃, and the control of reflux ratio of overhead condensation liquid is 0.2, and trichloromethane with DMAc takes place accurate the separation.The DMAc water ratio that obtains through rectifying separation at the bottom of the tower is lower than 200ppm, recycles as extraction agent behind the cat head trichloromethane vapour condensation.After extracting phase is discharged from multistage tower clarifying tank top, enter stripping tower, feed the superheated vapour stripping and go out a spot of trichloromethane in the extracting phase, recycle as extraction agent behind the trichloromethane vapour condensation, the concentration of trichloromethane is lower than 0.8ppm in the waste water of discharging at the bottom of the stripping tower.In the whole recovery process, the rate of recovery of DMAc is high in the filature wastewater, reaches 99.2%.The DMAc based on very high purity of discharging at the bottom of the tower can be used for the solution polymerization wet-spinning of aromatic polyamide fibre.
Embodiment 3:
With the trichloromethane is extraction agent, and 1 part of filature wastewater and 2.5 parts of extraction agent that contain 15%DMAc is quantitatively sent into multistage tower clarifying tank simultaneously, and the extraction of 10 stage countercurrents takes place under stirring action mixing solutions.Extraction agent extracts the whole DMAc in the filature wastewater, and the extraction phase of formation is made up of trichloromethane and DMAc; Extracting phase mainly is made up of salt and water, contains a spot of trichloromethane.Extraction phase enters rectifying tower after discharging from multistage tower clarifying tank bottom, and absolute pressure is constant in 20kPa in the rectifying tower, and column bottom temperature is constant in 120 ℃, and the control of reflux ratio of overhead condensation liquid is 0.2, and trichloromethane with DMAc takes place accurate the separation.The DMAc water ratio that obtains through rectifying separation at the bottom of the tower is lower than 200ppm, recycles as extraction agent behind the cat head trichloromethane vapour condensation.After extracting phase is discharged from multistage tower clarifying tank top, enter stripping tower, feed the superheated vapour stripping and go out a spot of trichloromethane in the extracting phase, recycle as extraction agent behind the trichloromethane vapour condensation, the concentration of trichloromethane is lower than 0.8ppm in the waste water of discharging at the bottom of the stripping tower.In the whole recovery process, the rate of recovery of DMAc is high in the filature wastewater, reaches 99.2%.The DMAc based on very high purity of discharging at the bottom of the tower can be used for the solution polymerization wet-spinning of aromatic polyamide fibre.
Embodiment 4:
With the trichloromethane is extraction agent, and 1 part of filature wastewater and 2.5 parts of extraction agent that contain 30%DMAc is quantitatively sent into multistage tower clarifying tank simultaneously, and the extraction of 15 stage countercurrents takes place under stirring action mixing solutions.Extraction agent extracts the whole DMAc in the filature wastewater, and the extraction phase of formation is made up of trichloromethane and DMAc; Extracting phase mainly is made up of salt and water, contains a spot of trichloromethane.Extraction phase enters rectifying tower after discharging from multistage tower clarifying tank bottom, and absolute pressure is constant in 10kPa in the rectifying tower, and column bottom temperature is constant in 100 ℃, and the control of reflux ratio of overhead condensation liquid is 0.2, and trichloromethane with DMAc takes place accurate the separation.The DMAc water ratio that obtains through rectifying separation at the bottom of the tower is lower than 200ppm, recycles as extraction agent behind the cat head trichloromethane vapour condensation.After extracting phase is discharged from multistage tower clarifying tank top, enter stripping tower, feed the superheated vapour stripping and go out a spot of trichloromethane in the extracting phase, recycle as extraction agent behind the trichloromethane vapour condensation, the concentration of trichloromethane is lower than 0.8ppm in the waste water of discharging at the bottom of the stripping tower.In the whole recovery process, the rate of recovery of DMAc is high in the filature wastewater, reaches 99.6%.The DMAc based on very high purity of discharging at the bottom of the tower can be used for the solution polymerization wet-spinning of aromatic polyamide fibre.
Embodiment 5:
With 1, the 2-ethylene dichloride is an extraction agent, and 1 part of filature wastewater and 3 parts of extraction agent that contain 5%DMAc is quantitatively sent into multistage tower clarifying tank simultaneously, and the extraction of 15 stage countercurrents takes place under stirring action mixing solutions.Extraction agent extracts the whole DMAc in the filature wastewater, and the extraction phase of formation is by 1, and 2-ethylene dichloride and DMAc form; Extracting phase mainly is made up of salt and water, contain a spot of 1, the 2-ethylene dichloride.Extraction phase enters rectifying tower after discharging from multistage tower clarifying tank bottom, and absolute pressure is constant in 10kPa in the rectifying tower, and column bottom temperature is constant in 100 ℃, and the control of reflux ratio of overhead condensation liquid is 0.01,1, and the 2-ethylene dichloride with DMAc takes place accurate the separation.The DMAc water ratio that obtains through rectifying separation at the bottom of the tower is lower than 200ppm, and cat head 1 recycles as extraction agent behind the 2-ethylene dichloride vapour condensation.After extracting phase is discharged from multistage tower clarifying tank top, enter stripping tower, feed the superheated vapour stripping and go out in the extracting phase a spot of 1, the 2-ethylene dichloride, 1, recycle as extraction agent behind the 2-ethylene dichloride vapour condensation, in the waste water of discharging at the bottom of the stripping tower 1, the concentration of 2-ethylene dichloride is lower than 0.8ppm.In the whole recovery process, the rate of recovery of DMAc is high in the filature wastewater, reaches 97%.The DMAc based on very high purity of discharging at the bottom of the tower can be used for the solution polymerization wet-spinning of aromatic polyamide fibre.
Comparative example: adopt the evaporation rectifying separation method of prior art, filature wastewater is at evaporating kettle internal heating to 180 ℃, and DMAC/ water evaporates together, and salt has been stayed at the bottom of the evaporating kettle.Condensed DMAC and water mixed solution enter rectifying tower, and under 120 ℃ high temperature, water with DMAc takes place accurate the separation at the bottom of the rectifying tower.The DMAc purity height of discharging at the bottom of the tower can be used for the solution polymerization wet-spinning of aromatic polyamide fibre.
To in that aromatic polyamide fibre production process two kinds of methods of purification DMAc component from filature wastewater---the purification result of the evaporation rectifying separation method of extraction fractional distillation of the present invention and prior art compares, and is as shown in the table:
| Thermal load (Mkcal/hr) | Reclaim yield (%) | Water ratio (ppm) | |
| Embodiment 1 | 0.61 | 99.1 | 180 |
| Embodiment 2 | 0.88 | 99.2 | 121 |
| Embodiment 3 | 1.50 | 99.2 | 57 |
| Embodiment 4 | 1.48 | 99.6 | 46 |
| Embodiment 5 | 3.70 | 97 | 185 |
| Comparative example | 5.72 | 76 | 400 |
From above table data as can be seen, the application of extraction agent of the present invention makes whole purification process energy consumption descend a lot, reclaiming yield has increased about 20%, has saved raw materials cost, and the water ratio of DMAc product has obtained reducing further.
Claims (7)
1. the method for a purifying dimethylacetamide from filature wastewater is characterized in that, its technological process comprises extraction and rectifying,
Described extraction process process is: extraction agent and filature wastewater carry out the hybrid extraction phase-splitting in extraction equipment, have formed extraction phase of being made up of extraction agent and N,N-DIMETHYLACETAMIDE and the extracting phase of being made up of salt, water and residual extraction agent;
Described rectification process process is: described extraction phase enters rectifying device, and extraction agent steam steams from cat head, recycle as extraction agent after the condensation, and N,N-DIMETHYLACETAMIDE is stayed at the bottom of the rectifying tower, after the discharging as the polymer raw reuse.
2. as claimed in claim 1 from filature wastewater the method for purifying dimethylacetamide, it is characterized in that its technological process also comprises stripping, described stripping process process is: the extracting phase that contains a small amount of extraction agent enters stripping apparatus, with the superheated vapour is steam stripping agent, and stripping goes out extraction agent wherein.
3. as claimed in claim 1 from filature wastewater the method for purifying dimethylacetamide, it is characterized in that described extraction agent is trichloromethane or 1, the 2-ethylene dichloride.
4. as claimed in claim 1 from filature wastewater the method for purifying dimethylacetamide, it is characterized in that described extraction equipment is multistage tower settler.
5. as claimed in claim 1 from filature wastewater the method for purifying dimethylacetamide, it is characterized in that, described extraction agent and filature wastewater are according to (2～10): 3 volume flow ratio, enter hybrid extraction in the extraction equipment with reflux type, extraction progression is 5～20 grades.
6. as claimed in claim 1 from filature wastewater the method for purifying dimethylacetamide, it is characterized in that, described rectifying device is the material filling type rectifying tower, absolute pressure is constant between 0～50kPa in the tower, column bottom temperature remains between 100～150 ℃, and control of reflux ratio is in 0.01～0.5 scope.
7. as claimed in claim 2 from filature wastewater the method for purifying dimethylacetamide, it is characterized in that described stripping apparatus is the material filling type stripping tower, tower top temperature is constant between 85～115 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007100377972A CN101255122A (en) | 2007-03-02 | 2007-03-02 | Method for purifying dimethylacetamide from spinning wastewater |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007100377972A CN101255122A (en) | 2007-03-02 | 2007-03-02 | Method for purifying dimethylacetamide from spinning wastewater |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101255122A true CN101255122A (en) | 2008-09-03 |
Family
ID=39890287
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2007100377972A Pending CN101255122A (en) | 2007-03-02 | 2007-03-02 | Method for purifying dimethylacetamide from spinning wastewater |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101255122A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102659613A (en) * | 2012-04-18 | 2012-09-12 | 中国天辰工程有限公司 | Method for recovering dimethyl formamide (DMF) cleaning agent for styrene-acrylonitrile (SAN) copolymer production device |
| CN102993039A (en) * | 2012-12-18 | 2013-03-27 | 常州大学 | Method for recovering dimethyl acetamide in polyether sulfone spinning wastewater |
| CN107089764A (en) * | 2017-04-25 | 2017-08-25 | 湖北绿色家园材料技术股份有限公司 | A kind of water reuse method in polyamide production |
| CN110078285A (en) * | 2019-05-08 | 2019-08-02 | 徐州工程学院 | A kind of Urethane Elastic Fibre Industrial Wastewater efficient treatment process |
| CN112574060A (en) * | 2019-09-29 | 2021-03-30 | 中国石油化工股份有限公司 | Method for recovering N, N-dimethylacetamide |
-
2007
- 2007-03-02 CN CNA2007100377972A patent/CN101255122A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102659613A (en) * | 2012-04-18 | 2012-09-12 | 中国天辰工程有限公司 | Method for recovering dimethyl formamide (DMF) cleaning agent for styrene-acrylonitrile (SAN) copolymer production device |
| CN102993039A (en) * | 2012-12-18 | 2013-03-27 | 常州大学 | Method for recovering dimethyl acetamide in polyether sulfone spinning wastewater |
| CN107089764A (en) * | 2017-04-25 | 2017-08-25 | 湖北绿色家园材料技术股份有限公司 | A kind of water reuse method in polyamide production |
| CN107089764B (en) * | 2017-04-25 | 2021-04-30 | 湖北绿色家园材料技术股份有限公司 | Method for utilizing waste water in polyamide production |
| CN110078285A (en) * | 2019-05-08 | 2019-08-02 | 徐州工程学院 | A kind of Urethane Elastic Fibre Industrial Wastewater efficient treatment process |
| CN112574060A (en) * | 2019-09-29 | 2021-03-30 | 中国石油化工股份有限公司 | Method for recovering N, N-dimethylacetamide |
| CN112574060B (en) * | 2019-09-29 | 2022-10-11 | 中国石油化工股份有限公司 | Recovery method of N, N-dimethylacetamide |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| RU2396242C2 (en) | Method of methanol recuperation | |
| AU601419B2 (en) | Process for the separation of hydrocarbons from a mixed feedstock | |
| CN210085330U (en) | Separation device for recovering dimethyl sulfoxide | |
| CN104817470B (en) | A kind of five tower three-effect rectification system and the recovery methods thereof of DMAC or DMF waste liquid | |
| CN101255122A (en) | Method for purifying dimethylacetamide from spinning wastewater | |
| TWI794391B (en) | Purification of Solvent Used in Extractive Distillation Separation of Styrene and Styrene Separation Method | |
| CN109336803A (en) | A kind of method and its system of NMP devil liquor recovery production super-clean high-purity solvent | |
| CN108658051B (en) | Method and device for recovering nitration waste acid and sulfuric acid recovered by method and device | |
| CN100384818C (en) | Process for refining high purifity hexanpropylamide | |
| CN106045872A (en) | System for recovering DMF (dimethylformamid) waste liquor with pervaporation method and method | |
| CN103896840B (en) | The method and apparatus of continuous production epsilon-caprolactams | |
| CN107032555A (en) | A kind of method for handling oil-containing coal gasification waste water | |
| CN110862330A (en) | Efficient energy-saving rectification process for recycling DMAC waste liquid | |
| CN108779194B (en) | Process for extracting polyolefins | |
| CN111514602B (en) | Method and device for removing dichloromethane in high-boiling-point thermosensitive material | |
| CN109423318A (en) | After Atmospheric vacuum plus alkali directly produces the coal tar deep processing technique of crude naphthalene | |
| KR102520447B1 (en) | Solvent recovery method and solvent recovery apparatus | |
| CN116947728A (en) | Novel method and device for energy-saving recovery of NMP (N-methyl pyrrolidone) by single tower | |
| CN107459472A (en) | The process for purification of dimethyl sulfoxide solvent in carbon fibre precursor production process | |
| CN216106701U (en) | Device for separating cyclohexene | |
| RU2531993C1 (en) | Method for reclamation of isobutyl alcohol in production of high-strength aramid fibres | |
| CN109679679A (en) | A kind of heavy aromatics industrial process | |
| CN109134390B (en) | Continuous purification method of fluoroalkyl tetraconazole | |
| CN115215894B (en) | Preparation method of low-acid-value tetramethyl dihydro disiloxane | |
| CN115068966B (en) | Continuous desolventizing and refining method for hydrogenated petroleum resin |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Open date: 20080903 |