CN113828114A - Method and device for recycling dry spinning medium and spinning method and device - Google Patents

Method and device for recycling dry spinning medium and spinning method and device Download PDF

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Publication number
CN113828114A
CN113828114A CN202010591666.4A CN202010591666A CN113828114A CN 113828114 A CN113828114 A CN 113828114A CN 202010591666 A CN202010591666 A CN 202010591666A CN 113828114 A CN113828114 A CN 113828114A
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gas
organic solvent
absorbent
dry spinning
purified gas
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CN113828114B (en
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秦磊
陈亮
陈志坚
蔡立鑫
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1406—Multiple stage absorption
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D45/00—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces
    • B01D45/12—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces by centrifugal forces
    • B01D45/16—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces by centrifugal forces generated by the winding course of the gas stream, the centrifugal forces being generated solely or partly by mechanical means, e.g. fixed swirl vanes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1418—Recovery of products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1425—Regeneration of liquid absorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1487—Removing organic compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1493—Selection of liquid materials for use as absorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/18—Absorbing units; Liquid distributors therefor
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/04—Dry spinning methods
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F13/00—Recovery of starting material, waste material or solvents during the manufacture of artificial filaments or the like
    • 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)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Textile Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Gas Separation By Absorption (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The invention relates to the field of recovery of mixed gas in dry spinning, and discloses a method and a device for recovering and circulating a dry spinning medium, as well as a spinning method and a device, wherein the method comprises the steps of cooling and separating mixed gas containing an organic solvent generated in a spinning channel to obtain an organic solvent crude product A and primarily purified gas; under the absorption condition of an organic solvent, contacting the primarily purified gas with an absorbent to obtain secondary purified gas and the absorbent containing the organic solvent; carrying out regeneration treatment on an absorbent containing an organic solvent to obtain an organic solvent crude product B and a regenerated absorbent, and introducing the regenerated absorbent into a passage contacted with the primarily purified gas for recycling; and (3) contacting the secondary purified gas with water for tertiary purification, filtering and drying the tertiary purified gas, and introducing the filtered tertiary purified gas into a dry spinning channel for recycling. The method can realize deep separation of the organic solvent, and the separated gas and the organic solvent are respectively recycled, so that closed-loop recycling is realized.

Description

Method and device for recycling dry spinning medium and spinning method and device
Technical Field
The invention relates to the technical field of dry spinning, in particular to a method and a device for recovering and circulating a dry spinning medium and a spinning method and a device comprising the method and the device for recovering and circulating the dry spinning medium.
Background
The chemical fiber is a fiber with textile performance prepared by taking a natural polymer compound or an artificially synthesized polymer compound as a raw material through the processes of preparing a spinning solution, spinning, post-treating and the like, and is widely applied to the aspects of people's life at present. The existing solution spinning technology is mainly divided into wet spinning, dry spinning and dry-wet spinning. The dry spinning is a common spinning mode, and the spinning solution is sprayed out from a spinning nozzle, while spinning, the organic solvent in the spinning is vaporized and removed by using high-temperature gas, the filaments are gradually solidified, and then the filaments are formed after stretching, washing and drying. Dry spinning is widely used in the spinning process of polyvinyl chloride fiber, polyvinyl alcohol fiber, acrylic fiber, spandex and other products.
The solvent used for dry spinning is often an organic solvent with a low boiling point and good solubility for high molecular polymers, wherein N-methylpyrrolidone, dimethyl sulfoxide, N-dimethylformamide and N, N-dimethylacetamide are some common spinning solvents. In dry spinning, the organic solvent is quickly vaporized by the high-temperature gas flowing rapidly and then discharged from the spinning shaft. If a large amount of mixed gas carrying organic solvent is directly discharged into the atmosphere without being treated, waste of solvent resources and serious environmental pollution are caused.
For this reason, some researchers have studied on the recovery of the solvent in the mixed gas generated by dry spinning, and proposed several solutions: firstly, the direct condensation method, i.e. condensing the organic solvent in the mixed gas by cooling or heat exchange to separate the mixed gas, for example, patent document CN103668489A, has the advantages of simple process, but the disadvantages of incomplete removal of the organic solvent, still carrying out a certain amount of the organic solvent by the gas, easy inactivation of the adsorption material, causing a certain environmental pollution in the spinning industry area, and low purity of the obtained organic solvent, which cannot directly satisfy the requirement for the application of the spinning organic solvent. Secondly, the temperature reduction + membrane separation method, namely firstly, the mixed gas is reduced to a certain temperature, then the separation between the gas and the organic solvent is carried out through the gas separation membrane, wherein the organic solvent is intercepted and sent to the storage tank, corresponding patents such as CN203639619U, the scheme is characterized in that the mixed gas is not required to be cooled excessively, the consumption of heat energy is reduced, but the price of the separation membrane is relatively expensive, and some acidic or corrosive liquid in the mixed gas can damage the separation membrane, and then the service life of the separation membrane is reduced, so that the treatment cost is high.
Therefore, how to develop a new method for recovering the solvent in the mixed gas is a new target for processing the mixed gas by dry spinning, on one hand, the quality of the recovered solvent is improved, so that the recovered solvent can be directly used for spinning, and on the other hand, the pollution of the gas to the environment is reduced.
Disclosure of Invention
The invention aims to provide a method and a device for recycling a dry spinning medium, a spinning method and a device, wherein the method and the corresponding device can effectively and deeply separate gas and organic solvent in mixed gas containing the organic solvent generated in a dry spinning channel, and respectively recycle the separated gas and the separated organic solvent, so that the closed-loop recycling of the mixed gas for the dry spinning is realized, the pollution of gas emission to the environment is reduced, and the utilization rate of the organic solvent can be improved, so that the waste of the organic solvent is reduced.
In order to achieve the above object, the present invention provides, in one aspect, a method for recycling a dry spinning medium, comprising the steps of:
(a) cooling the mixed gas containing the organic solvent generated in the dry spinning channel, and then carrying out gas-liquid separation to obtain an organic solvent crude product A and a primary purified gas;
(b) under the absorption condition of an organic solvent, contacting the primarily purified gas with an absorbent to obtain secondary purified gas and the absorbent containing the organic solvent;
(c) carrying out regeneration treatment on an absorbent containing an organic solvent to obtain an organic solvent crude product B and a regenerated absorbent, and introducing the regenerated absorbent into a passage contacted with the primarily purified gas for recycling;
(d) and (3) contacting the secondary purified gas with water for tertiary purification, filtering and drying the tertiary purified gas, and introducing the filtered tertiary purified gas into a dry spinning channel for recycling.
In another aspect, the present invention provides a dry spinning method, which uses the above-mentioned dry spinning medium recycling method to purify and recycle the gas in the mixed gas in the dry spinning shaft or further regenerate the organic solvent in the mixed gas in the dry spinning shaft, and uses the regenerated organic solvent as the spinning solvent for recycling.
In another aspect, the present invention provides a dry spinning medium recycling apparatus, comprising:
the gas-liquid separator is used for carrying out gas-liquid separation on the cooled mixed gas containing the organic solvent to obtain an organic solvent crude product A and a primary purified gas;
the absorber is used for contacting the primarily purified gas with the absorbent to obtain secondary purified gas and the absorbent containing the organic solvent;
the absorbent regeneration tower is used for carrying out regeneration treatment on an absorbent containing an organic solvent to obtain an organic solvent crude product B and a regenerated absorbent, wherein a tower top gas outlet of the absorbent regeneration tower is communicated with the absorber;
the washing tank is used for washing the secondary purified gas to obtain a tertiary purified gas; and
and the filtering dryer is used for filtering and drying the outlet gas of the washing tank and then introducing the filtered gas into the dry spinning channel for recycling.
In a further aspect, the invention provides a dry spinning device, which comprises the dry spinning medium recycling device.
In the technical scheme, the gas which is primarily purified after gas-liquid separation can be purified again after absorbing residual organic solvent by the absorbent, the absorbent in the gas is removed by contacting with water, and the obtained gas can be dried and then can be recycled to the dry spinning channel; on the other hand, the absorbent can be recycled after being regenerated and contacted with the primarily purified gas; on the other hand, the organic solvent is recovered in the gas-liquid separation and absorbent regeneration treatment stages, and the recovery rate of the organic solvent is high. Therefore, the method and the corresponding device can effectively and deeply separate the gas and the organic solvent in the mixed gas containing the organic solvent generated in the dry spinning channel, the recovery rate of the organic solvent is high, the separated gas and the organic solvent are respectively recycled, the closed-loop recycling of the mixed gas of the dry spinning is realized, the pollution to the environment caused by gas emission is reduced, the utilization rate of the organic solvent can be improved, and the waste of the organic solvent is reduced.
Drawings
FIG. 1 is a schematic view of a dry spinning medium recovery cycle in one embodiment of the present invention;
FIG. 2 is a schematic view showing the construction of a cyclone-type demister in a preferred embodiment of the present invention.
Description of the reference numerals
1 gas-liquid separator 2 absorber
3 absorbent regeneration tower 4 washing tank
5 filtering drier 6 refining tower
7 heat exchanger 8 condenser
9 compressor 10 heater
11 cylindrical part 12 conical part
13 weir plate 14 draft tube
15 screen 16 condensation jacket
17 gas outlet of cyclone demister 18 liquid outlet of cyclone demister
21 mixed gas containing organic solvent 22 crude organic solvent A
23 primary purified gas 24 secondary purified gas
25 absorbent containing organic solvent 26 crude organic solvent B
27 regenerating the absorbent 28 three times to purify the gas
29 crude organic solvent 30 regenerated organic solvent
31 heavy fraction
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The invention provides a method for recycling a dry spinning medium, which comprises the following steps: (a) cooling the mixed gas containing the organic solvent generated in the dry spinning channel, and then carrying out gas-liquid separation to obtain an organic solvent crude product A and a primary purified gas; (b) under the absorption condition of an organic solvent, contacting the primarily purified gas with an absorbent to obtain secondary purified gas and the absorbent containing the organic solvent; (c) carrying out regeneration treatment on an absorbent containing an organic solvent to obtain an organic solvent crude product B and a regenerated absorbent, and introducing the regenerated absorbent into a passage contacted with the primarily purified gas for recycling; (d) and (3) contacting the secondary purified gas with water for tertiary purification, filtering and drying the tertiary purified gas, and introducing the filtered tertiary purified gas into a dry spinning channel for recycling.
In the above technical solution, the organic solvent contained in the mixed gas is an organic solvent used in conventional dry spinning, for example, decalin, N-methylpyrrolidone, dimethylsulfoxide, N-dimethylformamide, N-dimethylacetamide, and the like, and among them, four solvents of N-methylpyrrolidone, dimethylsulfoxide, N-dimethylformamide, and N, N-dimethylacetamide have high solubility in the polymer and are stable in properties, and are considered as the four most commonly used solvents in dry spinning. Preferably, the organic solvent contained in the mixed gas is at least one of N-methylpyrrolidone, dimethyl sulfoxide, N-dimethylformamide and N, N-dimethylacetamide.
Air, nitrogen and the like are generally used as media of hot air flow in dry spinning, and inert gas may be used as the media of the hot air flow for some special fibers. Preferably, the gas in the mixed gas is at least one of air, nitrogen, helium and argon. Further preferably, the oxygen content in the mixed gas is not higher than 11 vol%. The concentration of the organic solvent in the mixed gas containing the organic solvent generated in the dry spinning channel is influenced by the flow velocity of the medium of the hot airflow, so that the concentration of the organic solvent in the mixed gas containing the organic solvent has a wide range, and the volume fraction of the organic solvent in the mixed gas containing the organic solvent is 0.5-15 percent generally; according to the technical scheme of the invention, the gas in the mixed gas containing the organic solvent generated in the dry spinning channel can be effectively and deeply separated from the organic solvent.
In a preferred embodiment of the present invention, in order to improve the recovery rate of the organic solvent and further reduce the energy consumption for gas purification, the temperature of the mixed gas after temperature reduction in step (a) is preferably 25 ℃ to 80 ℃; therefore, most of the organic solvent can be condensed at the temperature, and the separation efficiency of the organic solvent in the mixed gas can be improved.
In order to further reduce energy consumption and improve heat utilization efficiency, preferably, the cooling in step (a) includes exchanging heat between the mixed gas containing the organic solvent and the filtered and dried tertiary purified gas generated in the dry spinning shaft, so that the temperature of the filtered and dried tertiary purified gas is increased and then the tertiary purified gas is introduced into the dry spinning shaft for recycling; and then the mixed gas containing the organic solvent after heat exchange is condensed, so that the mixed gas containing the organic solvent is cooled, and the heat in the mixed gas containing the organic solvent can be transferred to the third purified gas, thereby providing heat for the high-temperature gas required by the dry spinning channel. Further preferably, the gas-liquid separation is performed under a condition that the boiling point of the organic solvent is at least 30 ℃ lower than that of the organic solvent, so that the organic solvent enters a liquid phase after the gas-liquid separation as much as possible, thereby improving the separation efficiency and reducing the energy consumption.
For the absorbent, water is generally selected in the conventional knowledge, that is, the mixed gas containing the organic solvent generated in the dry spinning shaft is cooled and then subjected to gas-liquid separation to obtain crude organic solvent a and primarily purified gas, the primarily purified gas is contacted with water to obtain secondary purified gas and water containing the organic solvent, and subsequently, the water containing the organic solvent needs to be separated and regenerated again (for example, a regeneration tower and a refining tower) to obtain purified water and recover the organic solvent therein. The inventors of the present invention have studied and found that the content of the organic solvent in the initially purified gas is already low after the gas-liquid separation, and if water is used as the absorbent, the content of the organic solvent absorbed in the water is not high even after the initially purified gas is brought into contact with the water, and the organic solvent is difficult to separate from the water, and the energy consumption is high, which makes the regeneration of the water containing the organic solvent difficult, and the recovery rate of the organic solvent is low. The inventor of the invention is proved through research and verification that under the condition that the absorbent is selected to be low-chain alcohol, the recovery rate of the organic solvent and the purification rate of the organic solvent in secondary purified gas can be ensured, and further, the energy consumption can be reduced in the subsequent regeneration process of the absorbent. Furthermore, the absorbent in the secondary purified gas can be removed by a simple method in combination with the subsequent tertiary purification by contacting the secondary purified gas with water. Namely, the low-chain alcohol is adopted as the absorbent, so that the recovery rate of the organic solvent and the purification effect on gas can be ensured, and the energy consumption can be reduced. In a preferred embodiment of the present invention, the absorbent in step (b) is low-chain alcohol, which is a green solvent, and has good absorption capacity for organic solvents such as decalin, N-methylpyrrolidone, dimethyl sulfoxide, N-dimethylformamide, and N, N-dimethylacetamide. Meanwhile, compared with water, the low-chain alcohol has smaller vaporization enthalpy, and the energy consumption required by the regeneration of the subsequent absorbent and the purification of the organic solvent is also lower. Preferably, the absorbent in step (b) is a monohydric or polyhydric alcohol containing from 1 to 6 carbon atoms; preferably at least one of methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol and tert-butanol. By adopting the preferable absorbent, the absorbent and the organic solvent can be conveniently separated, the purity of the recovered organic solvent is improved, and the aim of recycling is better fulfilled.
In a preferred embodiment of the present invention, step (b) further comprises the step of compressing the primary purified gas before contacting the primary purified gas with the absorbent; preferably, the compression conditions are such that the primary purified gas is contacted with the absorbent at a pressure of from 0.15 to 1 MPa; preferably, the absorption conditions of the organic solvent in step (b) include: the pressure is 0.15-1 MPa; the volume ratio of the gas primarily purified in the step (b) to the absorbent is 5-30: 1. the main purpose of pressurizing the gas is to increase the kinetic difference of the gas in the absorber, so as to achieve better mixing and absorption.
In the present invention, the pressure is absolute pressure unless otherwise specified.
The regeneration process of the absorbent can be carried out under negative pressure or normal pressure, and the preferred regeneration mode is rectification, the pressure is 20kPa-100kPa, the reflux ratio is 0.2-2, and the temperature is 102-204 ℃. Under the condition, the absorbent can be effectively distilled off from the top of the absorbent regeneration tower, and the organic solvent is ensured to be left at the bottom of the tower kettle, so that the absorbent is separated from the organic solvent, the absorbent is regenerated and recycled, and the organic solvent is recovered at the stage, thereby improving the recovery rate of the organic solvent.
The contacting of the secondary purge gas with water in step (d) may also be referred to as a water wash of the secondary purge gas. In a preferred embodiment of the invention, the ratio of the volumetric flow rate of the secondary purge gas to the volumetric flow rate of water in step (d) is 30 to 100: 1. thus, the absorbent and trace organic solvent entrained in the secondary purified gas can be removed after contacting with water.
Preferably, the filtration drying mode comprises cyclone defoaming dehydration and then adsorption dehydration by contacting with a molecular sieve adsorbent. Therefore, liquid particles carried in the gas can be removed, and the purification quality of the gas is improved, so that the subsequent gas recycling is facilitated.
In the invention, in order to improve the utilization rate of the organic solvent, the solvent is preferably refined again to reach the recycling standard, and the method preferably further comprises the step (e) of rectifying the crude organic solvent A and the crude organic solvent B to obtain the regenerated organic solvent. Further preferably, the purity of the regenerated organic solvent is not lower than 99%, and the method further comprises the step of conveying the regenerated organic solvent into a dry spinning shaft for recycling, so that the method further realizes the closed circulation of the organic solvent. The rectification may be carried out under negative or normal pressure, preferably, the conditions of the rectification in step (e) include: the reflux ratio is 0.5-4, the temperature is 100-202 ℃, and the pressure is 20-100 kPa. Under the condition, the high-purity regenerated organic solvent can be obtained at the tower top, and the solvent indiscriminate application requirement of dry spinning is met.
In another aspect, the present invention provides a dry spinning method, which uses the above-mentioned dry spinning medium recycling method to purify and recycle the gas in the mixed gas in the dry spinning shaft or further regenerate the organic solvent in the mixed gas in the dry spinning shaft, and uses the regenerated organic solvent as the spinning solvent for recycling.
Further operations of dry spinning can be carried out with reference to the prior art.
In still another aspect, the present invention provides a dry spinning medium recycling apparatus, as shown in fig. 1, including: the gas-liquid separator 1 is used for performing gas-liquid separation on the cooled mixed gas 21 containing the organic solvent to obtain crude organic solvent A22 and primarily purified gas 23; an absorber 2 for contacting the primary purified gas 23 with an absorbent to obtain a secondary purified gas 24 and an absorbent 25 containing an organic solvent; the absorbent regeneration tower 3 is used for carrying out regeneration treatment on the absorbent 25 containing the organic solvent to obtain an organic solvent crude product B26 and a regenerated absorbent 27, wherein the tower top gas outlet of the absorbent regeneration tower 3 is communicated with the absorber 2; a washing tank 4 for washing the secondary purified gas 24 to obtain a tertiary purified gas 28; and the filtering dryer 5 is used for filtering and drying the gas at the outlet of the washing tank 4 so as to meet the requirement of introducing the dry spinning channel for recycling.
The gas-liquid separator 1 may employ a conventional gas-liquid separator in the art, such as a gravity settling type gas-liquid separator, a baffling separation type gas-liquid separator, a baffle separation type gas-liquid separator, a centrifugal separation type gas-liquid separator, a packing separation type gas-liquid separator, a wire mesh separation type gas-liquid separator, a microfiltration separation type gas-liquid separator, and the present invention may be implemented. In the examples hereinafter, a centrifugal separation type gas-liquid separator is employed.
The absorber 2 can adopt traditional absorption tower, for example packed tower, turbulent ball tower, plate tower etc. also can adopt the hypergravity absorption tower, and preferably, the absorber 2 is the hypergravity absorption tower, and the hypergravity absorption tower has occupation of land small in size, and gas-liquid contact is effectual, and contact time advantage such as short compares in traditional absorption tower, has efficiently, is fit for applying to the absorption of a small amount of organic solvent in the gas more and gets rid of. In the examples hereinafter, the absorber 2 employed is a conventional tray column.
The absorbent regeneration tower 3 may be a conventional tower, such as a bare tower, a packed tower, a turbulent ball tower, a tray tower, etc., and the present invention may be implemented. In the examples which follow, a conventional tray column is employed.
The washing tank 4 may be a general tank, and the present invention can be implemented as long as the gas is directly contacted with water in the gas passage. Preferably, the gas inlet end extends deep into the bottom of the tank and the gas outlet end is above the top of the tank. The purpose of the washing tank 4 is mainly to absorb trace amounts of organic solvents and absorbents in the gas.
In a preferred embodiment of the invention, the apparatus further comprises a refining tower 6, and the feed inlets of the refining tower 6 are respectively communicated with the discharge outlet of the gas-liquid separator 1 and the discharge outlet of the absorbent regeneration tower 3, and are used for rectifying the crude organic solvent A22 and the crude organic solvent B26 to obtain the regenerated organic solvent 30. The refining column 6 may employ a conventional rectification column such as a packed column, a tray column.
In order to further improve the utilization rate of heat and further reduce the energy consumption, the device preferably further comprises a heat exchanger 7, wherein a hot fluid inlet of the heat exchanger 7 is communicated with a gas outlet of the dry spinning shaft, and a cold fluid inlet of the heat exchanger 7 is communicated with a gas outlet of the filtering and drying device. Thus, the mixed gas 21 containing the organic solvent and generated in the dry spinning shaft can exchange heat with the filtered and dried tertiary purified gas 28, so that the temperature of the filtered and dried tertiary purified gas 28 is increased and then the tertiary purified gas is introduced into the dry spinning shaft for recycling. The heat exchanger 7 is a conventional heat exchanger in chemical engineering, such as a dividing wall type heat exchanger or a jacketed type heat exchanger.
Preferably, the device further comprises a heater 10 arranged between the heat exchanger 7 and the air inlet of the dry spinning shaft, and the heater is used for heating the tertiary purified gas 28 after heat exchange so as to further increase the temperature of the tertiary purified gas 28 and enable the tertiary purified gas to meet the air inlet requirement of entering the dry spinning shaft. The tertiary purified gas 28 is heated to 160-250 ℃ by the heat exchanger 7 and the heater 10, the tertiary purified gas 28 can directly enter the spinning shaft, the temperature of the tertiary purified gas 28 is higher than the boiling point of the organic solvent, the organic solvent sprayed in the spinning process can be vaporized, and the organic solvent can be effectively vaporized into gas in the temperature range to form the mixed gas 21 containing the organic solvent.
In a preferred embodiment of the present invention, the apparatus further comprises a condenser 8, and the condenser 8 is disposed between the heat exchanger 7 and the gas-liquid separator 1 to further cool the mixed gas 21 containing the organic solvent after heat exchange, so as to meet the requirement of gas-liquid separation. The condenser 8 can be a conventional condenser in the field, for example, a shell and tube condenser with mixed gas in the tube and condensing agent on the tube, wherein the condensing agent can be at least one of water, brine and methanol; a double pipe condenser may also be used.
Preferably, the apparatus further comprises a compressor 9, said compressor 9 being arranged between the gas-liquid separator 1 and the absorber 2 to pressurize the primary purified gas 23. The compressor 9 may be of a type conventional in the art, such as reciprocating, rotary, centrifugal, etc., and may implement the present invention.
The filter-dryer 5 can be a conventional demister and/or dryer for removing liquid entrained by the gas. The filter-dryer 5 may be disposed at a gas outlet of the washing tank 4, or may be disposed outside the washing tank 4, wherein the filter-dryer 5 includes a demister and a dryer. The demister can be a baffle plate type, a ball type, a wire mesh, a centrifugal demister and the like. Preferably, the filter dryer 5 includes a cyclone skimmer that is effective to reduce the water content of the tertiary purge gas 28 and also to reduce the entrainment of absorbent in the tertiary purge gas 28 and absorbent loss.
In a preferred embodiment of the present invention, as shown in fig. 2, the upper part of the cyclone demister is a cylindrical part 11, the lower part is a conical part 12, and the side wall of the cylindrical part 11 is provided with a gas outlet; a liquid outlet is also arranged on the side wall of the cylindrical part 11 and below the conical part 12; a weir 13 is provided between the conical part 12 and the cylindrical part 11 and/or at the gas outlet for preventing liquid from being carried by the gas.
Preferably, the cyclone-type demister further comprises a guide pipe 14, one end of the guide pipe 14 is communicated with the gas outlet of the washing tank 4, the other end of the guide pipe can extend into the upper part of the conical part 12, and the outlet end of the guide pipe 14 is in a tangential relation with the inner wall of the conical part 12, so that the gas is attached to the wall and swirled after entering the conical part 12, and the separation of gas and liquid is realized in a swirling state.
It is further preferred that the inner wall of the conical part 12, at least one side of the weir plate 13 and the gas outlet are provided with a wire mesh 15 for removing liquid particles from the gas.
Still further preferably, the outer wall of the conical part 12 is provided with a condensing jacket 16, so that the water and the absorbent in the gas are further cooled down in a swirling state, and the content of the water and the absorbent in the tertiary purified gas 28 is reduced.
In a preferred embodiment of the invention, the filter-dryer 5 further comprises a dewatering tank communicating with the gas outlet of the cyclone demister; preferably, the gas passage in the dewatering tank is filled with molecular sieve; further preferably, the dehydration tank is a chromatographic column filled with molecular sieves; still further preferably, the molecular sieve is a type a commercially available molecular sieve. Preferably, the type a commercial molecular sieves are type 3A, type 4A and type 5A molecular sieves to further enhance the water removal effect on the gas.
The regeneration method of the molecular sieve can adopt a conventional regeneration method, such as heating, and further preferably, the regeneration method of the molecular sieve is to inject heat conducting oil heated to 300-.
According to a preferred embodiment of the present invention, as shown in fig. 1, the method of dry spinning medium recovery cycle comprises the steps of:
(a) exchanging heat of mixed gas 21 containing organic solvent generated in a dry spinning channel by a heat exchanger 7, condensing and cooling to 25-80 ℃ by a condenser 8, and then carrying out gas-liquid separation in a gas-liquid separator 1 to obtain crude product A22 of organic solvent and primary purified gas 23;
(b) pressurizing the primarily purified gas 23 to 0.15-1MPa by a compressor 9, and then introducing the primarily purified gas into an absorber 2, wherein the ratio of the volume flow rate of the primarily purified gas to the volume flow rate of an absorbent is 5-30: 1, contacting the gas 23 subjected to primary purification with an absorbent in an absorber 2 to obtain secondary purified gas 24 and an absorbent 25 containing an organic solvent;
(c) rectifying an absorbent 25 containing an organic solvent in an absorbent regeneration tower 3 at a reflux ratio of 0.2-2, a temperature of 102-204 ℃ and a pressure of 20-100 kPa to obtain an organic solvent crude product B26 and a regenerated absorbent 27, and introducing the regenerated absorbent 27 into a passage contacted with the primarily purified gas 23 for recycling;
(d) the secondary purified gas 24 is contacted with water in a washing tank 4 for tertiary purification (the volume flow rate ratio of the secondary purified gas to the water is 30-100: 1, the tertiary purified gas 28 is defoamed and filtered by a cyclone type demister shown in figure 2, then is introduced into a dehydration tank of an A-type molecular sieve chromatographic column for drying, then is subjected to heat exchange in a heat exchanger 7, is further heated to 160-250 ℃ by a heater 10, and is introduced into a dry spinning channel for recycling;
(e) recovering the crude organic solvent A22 and the crude organic solvent B26 to obtain crude organic solvents, rectifying the crude organic solvent 29 in a refining tower 6 (the reflux ratio is 0.5-4, the temperature is 100-202 ℃, and the pressure is 20kPa-100kPa) to obtain a regenerated organic solvent 30, wherein the heavy component 31 is arranged at the bottom of the tower;
(f) the regenerated organic solvent 30 is sent to a dry spinning shaft for cyclic utilization.
In a further aspect, the invention provides a dry spinning device, which comprises the dry spinning medium recycling device.
The dry spinning device can refer to the prior art, and is not described in detail herein.
The above preferred conditions can be arbitrarily combined to obtain preferred embodiments of the present invention without departing from the common general knowledge in the art.
The positive progress effects of the invention are as follows: the method can effectively deeply separate the gas and the organic solvent in the mixed gas, and the gas and the organic solvent can be respectively recycled, thereby realizing the closed-loop recycling of the mixed gas for dry spinning and reducing the pollution to the environment and the waste of resources.
The present invention will be described in detail below by way of examples. In the following examples, the content of the organic solvent in the mixed gas, the content of the organic solvent in the third purified gas, the content of the absorbent, and the purities of the absorbent and the organic solvent were all obtained by HPLC detection, and the water content was measured by a moisture meter; the% of the purity obtained means mass%.
The recovery rate of the organic solvent is a ratio of the total amount of the regenerated organic solvent to the total amount of the organic solvent contained in the mixed gas in percentage.
The following examples were carried out in the apparatus shown in FIG. 1, unless otherwise stated.
Example 1
With the apparatus shown in FIG. 1:
(a) 750Nm3The mixed gas (the oxygen concentration is 10 volume percent, the volume fraction of the organic solvent is 4.7 percent) containing the organic solvent, air and nitrogen generated in the dry spinning channel is subjected to heat exchange by a heat exchanger 7, condensed by a condenser 8 and cooled to 60 ℃, and then subjected to gas-liquid separation in a gas-liquid separator 1 to obtain crude organic solvent A and primarily purified gas;
(b) the gas to be purified is pressurized to 0.5MPa by a compressor 9 and then introduced into an absorber 2, wherein the ratio of the volume flow rate of the gas to the volume flow rate of an absorbent (ethanol, with an original purity of 99.58%) is 10: 1, contacting the primary purified gas with an absorbent in an absorber 2 (the number of tower plates is 10) to obtain secondary purified gas and the absorbent containing an organic solvent;
(c) rectifying an absorbent containing an organic solvent in an absorbent regeneration tower 3 (with the number of plates being 10), wherein the reflux ratio is 1, the temperature is 204 ℃, the pressure is 100kPa to obtain an organic solvent crude product B and a regenerated absorbent (with the purity being 99.52%), and introducing the regenerated absorbent into a passage contacted with the primarily purified gas for recycling;
(d) the secondary purified gas is contacted with water in a washing tank 4 to carry out tertiary purification (the volume ratio of the secondary purified gas to the water is 50: 1), the tertiary purified gas is defoamed and filtered by a cyclone type demister shown in figure 2, then is dried by a dehydration tank of a 3A type molecular sieve chromatographic column, is subjected to heat exchange in a heat exchanger 7, is further heated to 250 ℃ by a heater 10, and is then introduced into a dry spinning channel for recycling;
the content of organic solvent in the three purified gases after filtration and drying is less than 1mgNm3(i.e., below the limit of detection by HPLC), the absorbent content is 10mg/Nm3The content of water is 20mg/Nm3；
(e) Recovering the crude organic solvent A and the crude organic solvent B to obtain crude organic solvents, and rectifying the crude organic solvents in a refining tower 6 (the reflux ratio is 2, the temperature is 202 ℃, and the pressure is 100kPa) to obtain regenerated organic solvents, wherein the purity of the regenerated organic solvents is 99.72%, and the recovery rate of the organic solvents is 98.35%;
(f) feeding the regenerated organic solvent into a dry spinning channel for cyclic utilization;
wherein the organic solvent is N-methyl pyrrolidone, and the absorbent is ethanol. The results of this example are shown in Table 1.
In this embodiment, as shown in fig. 2, the upper part of the used cyclone demister is a cylindrical part 11, the lower part is a conical part 12, the sidewall of the cylindrical part 11 is provided with a gas outlet 17, and the gas outlet 17 is communicated with the gas inlet of the dewatering tank of the 3A type molecular sieve chromatographic column; a liquid outlet 18 is also arranged on the side wall of the cylindrical part 11 and below the conical part 12, and the liquid outlet 18 is communicated with a liquid inlet of the washing tank 4; weir plates 13 are arranged between the conical part 12 and the cylindrical part 11 and at the gas outlet; the cyclone demister further comprises a flow guide pipe 14, one end of the flow guide pipe 14 is communicated with a gas outlet of the washing tank 4, the other end of the flow guide pipe 14 can extend into the upper part of the conical part 12, and the outlet end of the flow guide pipe 14 is in a tangential relation with the inner wall of the conical part 12, so that the tertiary purified gas 28 passing through the washing tank 4 enters the conical part 12 from the upper part and then flows back to the wall; silk screens 15 are arranged on the inner wall of the conical part 12, two sides of the weir plate 13 and the gas outlet; a condensation jacket 16 is arranged on the outer wall of the conical part 12, and a refrigerant (brine) is filled in the condensation jacket 16.
Example 2
With the apparatus shown in FIG. 1:
(a) at least 800Nm3Mixed gas (oxygen concentration is 8.5 volume percent, volume fraction of organic solvent is 2.5 percent) containing organic solvent, air and nitrogen generated in a dry spinning channelExchanging heat by a heat exchanger 7, condensing and cooling to 80 ℃ by a condenser 8, and then carrying out gas-liquid separation in a gas-liquid separator 1 to obtain an organic solvent crude product A and a primary purified gas;
(b) the gas to be purified is pressurized to 1MPa by a compressor 9 and then introduced into an absorber 2, wherein the ratio of the volume flow rate of the gas to the volume flow rate of an absorbent (propanol, with an original purity of 99.54%) is 30: 1, contacting the primary purified gas with an absorbent in an absorber 2 (the number of tower plates is 15) to obtain secondary purified gas and the absorbent containing an organic solvent;
(c) rectifying an absorbent containing an organic solvent in an absorbent regeneration tower 3 (with the number of trays being 25), wherein the reflux ratio is 2, the temperature is 149 ℃, the pressure is 60kPa, so as to obtain an organic solvent crude product B and a regenerated absorbent (with the purity being 99.51%), and introducing the regenerated absorbent into a passage contacted with the primarily purified gas for recycling;
(d) the secondary purified gas is contacted with water in a washing tank 4 to carry out tertiary purification (the volume ratio of the secondary purified gas to the water is 100: 1), the tertiary purified gas is defoamed and filtered by a cyclone type demister shown in figure 2, then is dried by a dehydration tank of a 5A type molecular sieve chromatographic column, is subjected to heat exchange in a heat exchanger 7, is further heated to 250 ℃ by a heater 10, and is then introduced into a dry spinning channel for recycling;
the content of organic solvent in the purified gas after filtering and drying is less than 1mg/Nm3The content of the absorbent is less than 2mg/Nm3(i.e., below the limit of detection by HPLC), the water content is 30mg/Nm3；
(e) Recovering the organic solvent crude product A and the organic solvent crude product B to obtain an organic solvent crude product, and rectifying the organic solvent crude product in a refining tower 6 (the reflux ratio is 4, the tower top temperature is 147 ℃, and the pressure is 60kPa) to obtain a regenerated organic solvent, wherein the purity of the regenerated organic solvent is 99.81%, and the recovery rate of the organic solvent is 98.31%;
(f) feeding the regenerated organic solvent into a dry spinning channel for cyclic utilization;
wherein the organic solvent is N, N-dimethylacetamide, and the absorbent is propanol. The cyclone demister in this embodiment is the same as that in embodiment 1. The results of this example are shown in Table 1.
Example 3
With the apparatus shown in FIG. 1:
(a) 1000Nm3The mixed gas (the oxygen concentration is 7 volume percent, the volume fraction of the organic solvent is 1.2 percent) containing the organic solvent, air and nitrogen generated in the dry spinning channel is subjected to heat exchange by a heat exchanger 7, is condensed by a condenser 8 and cooled to 25 ℃, and then is subjected to gas-liquid separation in a gas-liquid separator 1, wherein the gas-liquid separation temperature is 25 ℃, so that crude organic solvent A and primarily purified gas are obtained;
(b) pressurizing the primarily purified gas to 0.15MPa by a compressor 9, and introducing the primarily purified gas into an absorber 2, wherein the volume ratio of the primarily purified gas to an absorbent (n-butanol, the purity is 99.52%) is 5: 1, contacting the primary purified gas with an absorbent in an absorber 2 (the number of tower plates is 12) to obtain secondary purified gas and the absorbent containing an organic solvent;
(c) rectifying the absorbent containing the organic solvent in an absorbent regeneration tower 3 (with the number of tower plates being 18) at a reflux ratio of 0.2, a temperature of 139 ℃ and a pressure of 20kPa to obtain an organic solvent crude product B and a regenerated absorbent (with a purity of 99.51%), and introducing the regenerated absorbent into a passage in contact with the primarily purified gas for recycling;
(d) the secondary purified gas is contacted with water in a washing tank 4 to carry out tertiary purification (the volume ratio of the secondary purified gas to the water is 30: 1), the tertiary purified gas is defoamed and filtered by a cyclone type demister shown in figure 2, then is dried by a dehydration tank of a 3A type molecular sieve chromatographic column, is subjected to heat exchange in a heat exchanger 7, is further heated to 200 ℃ by a heater 10, and is then introduced into a dry spinning channel for recycling;
the content of organic solvent in the purified gas after filtering and drying is less than 1mg/Nm3The content of the absorbent is 14mg/Nm3The water content is 12mg/Nm3；
(e) Recovering the crude organic solvent A and the crude organic solvent B to obtain crude organic solvents, and rectifying the crude organic solvents in a refining tower 6 (the reflux ratio is 0.5, the temperature at the top of the tower is 137 ℃, and the pressure is 20kPa) to obtain regenerated organic solvents, wherein the purity of the regenerated organic solvents is 99.64%, and the recovery rate of the organic solvents is 98.72%;
(f) feeding the regenerated organic solvent into a dry spinning channel for cyclic utilization;
wherein the organic solvent is dimethyl sulfoxide, and the absorbent is n-butanol (purity of 99.52%). The cyclone demister in this embodiment is the same as that in embodiment 1. The results of this example are shown in Table 1.
Example 4
A dry spinning medium recovery cycle was performed as in example 1, except that the absorbent ethanol was changed to water.
The results of this example are shown in Table 1.
Example 5
A dry spinning medium recovery cycle was performed as in example 1 except that the cyclone skimmer of example 1 was not used and the tertiary purge gas was passed directly to the dewatering tank of a type 3A molecular sieve chromatography column.
The content of the organic solvent in the filtered and dried three purified gases obtained in the step (d) is less than 1mg/Nm3The content of the absorbent is 15mg/Nm3The water content is 35mg/Nm3。
The results of this example are shown in Table 1.
Example 6
The dry spinning medium recovery cycle was performed as in example 1, except that the cyclone skimmer of example 1 was used to remove the weir plate, i.e., a cyclone skimmer without a weir plate.
The content of the organic solvent in the filtered and dried three purified gases obtained in the step (d) is less than 1mg/Nm3The content of the absorbent is 13mg/Nm3The water content was 22mg/Nm3。
The results of this example are shown in Table 1.
Example 7
The dry spinning medium recovery cycle was performed in the same manner as in example 1, except that the cyclone type demister in example 1 was used without a weir plate and a wire mesh and without adding a refrigerant to a condensation jacket, that is, a cyclone type demister which is not provided with a weir plate, a wire mesh and a non-condensation was used.
The content of the organic solvent in the filtered and dried three purified gases obtained in the step (d) is less than 1mg/Nm3The content of the absorbent is 15mg/Nm3The water content is 32mg/Nm3。
The results of this example are shown in Table 1.
Example 8
A dry spinning medium recovery cycle was performed in the same manner as in example 1, except that the cyclone demister in example 1 was used to remove the wire mesh and no refrigerant was added to the condensation jacket, i.e., a cyclone demister without a wire mesh and which is not condensed was used.
The content of the organic solvent in the filtered and dried three purified gases obtained in the step (d) is less than 1mg/Nm3The content of the absorbent is 12mg/Nm3The water content is 25mg/Nm3。
The results of this example are shown in Table 1.
Example 9
The dry spinning medium recovery cycle was performed as in example 1, except that no refrigerant was added to the condensing jacket of the cyclone demister in example 1, i.e., a cyclone demister having no condensing function was used.
The content of the organic solvent in the filtered and dried three purified gases obtained in the step (d) is less than 1mg/Nm3The content of the absorbent is 11mg/Nm3The content of water is 20mg/Nm3。
The results of this example are shown in Table 1.
TABLE 1
Figure BDA0002555780110000191
Application example
Performing dry spinning medium recovery circulation according to the methods of examples 1 to 9, and continuously mechanically applying for 120h to obtain three purified gases, wherein the purified gases comprise the content of an organic solvent, the content of an absorbent and the content of water; purity of the regenerated absorbent; the purity of the regenerated organic solvent and the recovery rate of the organic solvent are shown in Table 2.
TABLE 2
Figure BDA0002555780110000201
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims (15)

1. A method for recycling a dry spinning medium, which is characterized by comprising the following steps:
(a) cooling the mixed gas containing the organic solvent generated in the dry spinning channel, and then carrying out gas-liquid separation to obtain an organic solvent crude product A and a primary purified gas;
(b) under the absorption condition of an organic solvent, contacting the primarily purified gas with an absorbent to obtain secondary purified gas and the absorbent containing the organic solvent;
(c) carrying out regeneration treatment on an absorbent containing an organic solvent to obtain an organic solvent crude product B and a regenerated absorbent, and introducing the regenerated absorbent into a passage contacted with the primarily purified gas for recycling;
(d) and (3) contacting the secondary purified gas with water for tertiary purification, filtering and drying the tertiary purified gas, and introducing the filtered tertiary purified gas into a dry spinning channel for recycling.
2. The method according to claim 1, wherein the mixed gas contains an organic solvent of at least one of N-methylpyrrolidone, dimethylsulfoxide, N-dimethylformamide and N, N-dimethylacetamide;
the gas in the mixed gas is at least one of air, nitrogen, helium and argon; preferably, the oxygen content in the mixed gas is not higher than 11 vol%.
3. The method according to claim 1 or 2, wherein the temperature of the mixed gas after temperature reduction in step (a) is 25-80 ℃;
the temperature reduction in the step (a) comprises the steps of firstly exchanging heat between mixed gas containing an organic solvent and the filtered and dried tertiary purified gas generated in the dry spinning channel, raising the temperature of the filtered and dried tertiary purified gas, and then introducing the gas into the dry spinning channel for recycling; then condensing the mixed gas containing the organic solvent after heat exchange;
preferably, the gas-liquid separation is performed under a condition that is at least 30 ℃ lower than the boiling point of the organic solvent.
4. A process according to claim 1 or 2 or 3, wherein the absorbent in step (b) is a mono-or polyol containing 1 to 6 carbon atoms; preferably at least one of methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol and tert-butanol;
preferably, step (b) further comprises the step of compressing the primary purified gas prior to contacting the primary purified gas with the absorbent; preferably, the compression conditions are such that the primary purified gas is contacted with the absorbent at a pressure of from 0.15 to 1 MPa;
further preferably, the absorption conditions of the organic solvent in step (b) include: the pressure is 0.15-1 MPa; the ratio of the volume flow rate of the gas primarily purified in the step (b) to the volume flow rate of the absorbent is 5-30: 1.
5. the process as claimed in any one of claims 1 to 4, wherein the regeneration treatment in step (c) is carried out by rectification, preferably at a reflux ratio of from 0.2 to 2 and at a temperature of from 102 ℃ to 204 ℃.
6. The method of any one of claims 1-5, wherein the ratio of the volumetric flow rate of the secondary purge gas to the volumetric flow rate of water in step (d) is 30-100: 1;
the filtering and drying mode comprises the steps of cyclone defoaming and dehydration, and then the cyclone defoaming and dehydration is carried out by contacting with a molecular sieve adsorbent to carry out adsorption dehydration.
7. The method of claim 6, wherein the cyclonic defoaming dewatering is performed in a cyclonic demister;
preferably, the upper part of the cyclone demister is a cylindrical part (11), the lower part of the cyclone demister is a conical part (12), and a gas outlet is arranged on the side wall of the cylindrical part (11); liquid outlets are also formed in the side wall of the cylindrical part (11) and below the conical part (12); a weir plate (13) is arranged between the conical part (12) and the cylindrical part (11) and/or at the gas outlet and is used for preventing liquid from being carried by gas;
preferably, the cyclone demister further comprises a flow guide pipe (14), one end of the flow guide pipe (14) is communicated with the secondary purified gas outlet, the other end of the flow guide pipe can extend into the upper part of the conical part (12), and the outlet end of the flow guide pipe (14) is in tangential relation with the inner wall of the conical part (12);
further preferably, the inner wall of the conical part (12), at least one side of the weir plate (13) and the gas outlet are provided with a wire mesh (15) for removing liquid particles in the gas;
still further preferably, a condensing jacket (16) is provided on the outer wall of the conical portion (12).
8. The method according to any one of claims 1 to 7, wherein the method further comprises the steps of (e) rectifying the crude organic solvent A and the crude organic solvent B to obtain a regenerated organic solvent;
the purity of the regenerated organic solvent is not lower than 99 percent, and the method also comprises the step of conveying the regenerated organic solvent into a dry spinning shaft for cyclic utilization;
preferably, the conditions for rectification in step (e) include: the reflux ratio is 0.5-4, and the temperature is 100-202 ℃.
9. A dry spinning method, characterized in that the method purifies and recycles the gas in the mixed gas in the dry spinning channel by the method of recovering and recycling the dry spinning medium according to any one of claims 1 to 8, or further regenerates the organic solvent in the mixed gas in the dry spinning channel, and recycles the regenerated organic solvent as the spinning solvent.
10. A dry spinning medium recycling device is characterized by comprising:
the gas-liquid separator (1) is used for carrying out gas-liquid separation on the cooled mixed gas containing the organic solvent to obtain an organic solvent crude product A and a primary purified gas;
the absorber (2) is used for contacting the primarily purified gas with an absorbent to obtain a secondary purified gas and the absorbent containing the organic solvent;
the absorbent regeneration tower (3) is used for carrying out regeneration treatment on an absorbent containing an organic solvent to obtain an organic solvent crude product B and a regenerated absorbent, wherein the tower top gas outlet of the absorbent regeneration tower (3) is communicated with the absorber (2);
a washing tank (4) for washing the secondary purified gas to obtain a tertiary purified gas; and
and the filtering dryer (5) is used for filtering and drying the gas at the outlet of the washing tank (4) so as to meet the requirement of introducing into a dry spinning channel for recycling.
11. The dry spinning medium recycling device according to claim 10, further comprising a refining tower (6), wherein the feed inlet of the refining tower (6) is respectively communicated with the discharge outlet of the gas-liquid separator (1) and the discharge outlet of the absorbent regeneration tower (3) for rectifying the crude organic solvent A and the crude organic solvent B to obtain a regenerated organic solvent;
and/or the device also comprises a heat exchanger (7), wherein a hot fluid inlet of the heat exchanger (7) is communicated with a gas outlet of the dry spinning shaft, and a cold fluid inlet of the heat exchanger (7) is communicated with a gas outlet for filtering and drying;
preferably, the device also comprises a heater (10) arranged between the heat exchanger (7) and the air inlet of the dry spinning shaft, and the heater is used for heating the tertiary purified gas after heat exchange.
12. The dry spinning medium recycling device according to claim 10 or 11, further comprising a condenser (8), wherein the condenser (8) is arranged between the heat exchanger (7) and the gas-liquid separator (1) to cool the mixed gas containing the organic solvent after heat exchange;
preferably, the apparatus further comprises a compressor (9), the compressor (9) being arranged between the gas-liquid separator (1) and the absorber (2) to pressurize the primarily purified gas.
13. The dry spinning media recovery cycle of any one of claims 10 to 12, wherein the filter dryer (5) comprises a cyclone demister;
preferably, the upper part of the cyclone demister is a cylindrical part (11), the lower part of the cyclone demister is a conical part (12), and a gas outlet is arranged on the side wall of the cylindrical part (11); liquid outlets are also formed in the side wall of the cylindrical part (11) and below the conical part (12); a weir plate (13) is arranged between the conical part (12) and the cylindrical part (11) and/or at the gas outlet and is used for preventing liquid from being carried by gas;
preferably, the cyclone-type demister further comprises a guide pipe (14), one end of the guide pipe (14) is communicated with the gas outlet of the washing tank (4), the other end of the guide pipe can extend into the upper part of the conical part (12), and the outlet end of the guide pipe (14) is in tangential relation with the inner wall of the conical part (12);
further preferably, the inner wall of the conical part (12), at least one side of the weir plate (13) and the gas outlet are provided with a wire mesh (15) for removing liquid particles in the gas;
still further preferably, a condensing jacket (16) is provided on the outer wall of the conical portion (12).
14. The dry spinning media recovery cycle of claim 13, wherein said filter-dryer (5) further comprises a dewatering tank in communication with a gas outlet of said cyclone-type demister;
preferably, the gas passage in the dewatering tank is filled with molecular sieve;
further preferably, the dehydration tank is a chromatographic column filled with molecular sieves;
still further preferably, the molecular sieve is a type a commercially available molecular sieve.
15. A dry spinning apparatus comprising the dry spinning medium recycling apparatus of any one of claims 10 to 14.
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