Comprehensive recovery device and comprehensive recovery method for meta-aramid polymerization byproducts

Abstract

The invention relates to a comprehensive recovery device and a comprehensive recovery method for meta-aramid polymerization byproducts, in particular to the technical field of high-performance fibers, and the comprehensive recovery device comprises drying equipment, gas-solid separation equipment, condensing equipment, a solvent recovery tank, a vacuum buffer tank and a solvent conveying pump set; a gas phase outlet of the drying equipment is connected with the condensing equipment through the gas-solid separation equipment; a gas phase outlet of the condensing equipment is connected with the vacuum buffer tank; the condensing equipment or the vacuum buffer tank is connected with a vacuum pump set; a liquid phase outlet of the condensing equipment is connected with the solvent recovery tank; a solid phase outlet of the drying equipment is sequentially connected with mixing equipment, solid-liquid separation equipment, concentration equipment, crystallization equipment and dehydration equipment. The device provided by the invention realizes efficient recovery of ammonium salt and solvent DMAC in the meta-aramid polymerization by-product, and is beneficial to resource utilization of the meta-aramid polymerization by-product, so that the utilization rate of related materials is increased, and green sustainable development of meta-aramid is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of high-performance fibers, and in particular to a comprehensive recovery device and method for meta-aramid polymerization byproducts, and in particular to an environmentally friendly and energy-saving drying system and process method for meta-aramid polymerization byproducts. Background Art

[0002] At present, HCl is produced during the polymerization of meta-aramid, and ammonia is required for neutralization reaction to generate NH4Cl. In order to ensure a salt-free polymerization system, it needs to be filtered out. However, the filtered NH4Cl contains DMAC solvent and a trace amount of oligomers. In order to achieve the goal of recovering DMAC solvent to reduce costs and comprehensively utilize NH4Cl, it needs to be treated to recover the DMAC solvent and completely separate NH4Cl for by-products.

[0003] CN113355764A discloses a one-step method for preparing colored meta-aramid fiber, which belongs to the technical field of aramid fiber preparation and includes the synthesis and spinning of colored meta-aramid polymer. The synthesis of colored meta-aramid polymer includes the following steps: dissolving meta-phenylenediamine in an amide polar organic solvent; controlling the reaction temperature to -10-0°C, adding a corresponding amount of 90-95wt% of isophthaloyl chloride to carry out a low-temperature polycondensation reaction; then adding a colored pigment, adding the remaining corresponding amount of 5-10wt% of isophthaloyl chloride to continue the low-temperature polycondensation reaction; and neutralizing the by-product hydrogen chloride with an alkaline earth metal oxide, hydroxide or ammonia, and controlling the temperature of the neutralization reaction to be lower than 30°C.

[0004] At present, rotary drum dryers are mostly used for drying NH4Cl. The rotary drum dryers have the following problems:

[0005] (1) The degree of automation control is low and the operation intensity of personnel is high;

[0006] (2) Using steam as a heat medium to heat and evaporate the DMAC solvent in the NH4Cl filter material for recovery, thus consuming a large amount of steam;

[0007] (3) When NH4Cl is heated to 100°C, it begins to decompose into NH3 and HCl. HCl is highly corrosive to the equipment. Under this condition, the service life of the equipment is short, resulting in a huge waste of investment.

[0008] (4) NH4Cl is evaporated to remove the solvent and becomes powder. In addition, the poor sealing of the dryer can easily lead to a deterioration of the working environment, thus affecting the occupational health of employees.

[0009] (5) The recovery rate of solvent DMAC is low.

[0010] In summary, the existing recovery process for meta-aramid polymerization by-products still has the defects of high energy consumption, severe equipment corrosion, poor working environment and poor recovery effect. Summary of the invention

[0011] In view of the problems existing in the prior art, the purpose of the present invention is to provide a comprehensive recovery device and a comprehensive recovery method for meta-aramid polymerization by-products, so as to solve the defects of the existing recovery process for meta-aramid polymerization by-products, such as high energy consumption, severe equipment corrosion, poor working environment and poor recovery effect.

[0012] To achieve this object, the present invention adopts the following technical solutions:

[0013] In a first aspect, the present invention provides a comprehensive recovery device for meta-aramid polymerization byproducts, the comprehensive recovery device comprising:

[0014] Drying equipment, gas-solid separation equipment, condensation equipment, solvent recovery tank, vacuum buffer tank, solvent delivery pump set;

[0015] The gas phase outlet of the drying device is connected to the condensing device through the gas-solid separation device;

[0016] The gas phase outlet of the condensing device is connected to the vacuum buffer tank;

[0017] The condensing device or the vacuum buffer tank is connected to a vacuum pump group;

[0018] The liquid phase outlet of the condensing device is connected to the solvent recovery tank;

[0019] The solvent recovery tank is connected to the solvent secondary utilization end through a solvent delivery pump group;

[0020] The solid phase outlet of the drying device is sequentially connected with a mixing device, a solid-liquid separation device, a concentration device, a crystallization device and a dehydration device.

[0021] The comprehensive recovery device provided by the present invention realizes the efficient recovery of ammonium salt and solvent DMAC in meta-aramid polymerization by-products, is beneficial to the resource utilization of meta-aramid polymerization by-products, thereby improving the utilization rate of related materials, and is beneficial to the green and sustainable development of meta-aramid.

[0022] As a preferred technical solution of the present invention, the drying equipment includes a heating jacket and / or a hollow heating rake.

[0023] Preferably, the hollow heating rake is provided with a transmission device.

[0024] As a preferred technical solution of the present invention, the solvent recovery tank is connected to an emptying receiving tank.

[0025] As a preferred technical solution of the present invention, the heat medium outlet of the drying device is connected to the heat medium inlet of the dehydration device;

[0026] Preferably, the crystallization device comprises at least 2 stages of crystallization devices;

[0027] Preferably, the gas phase condensate outlet of the concentration device is connected to the liquid inlet of the mixing device;

[0028] Preferably, the heat medium outlet of the dehydration device is connected to the heat medium inlet of the concentration device.

[0029] In a second aspect, the present invention provides a comprehensive recovery method for meta-aramid polymerization byproducts, the comprehensive recovery method comprising:

[0030] feeding the meta-aramid polymerization byproduct into a drying device for drying to obtain crude ammonium chloride and gas;

[0031] The crude ammonium chloride is mixed, solid-liquid separated, concentrated and crystallized to obtain purified ammonium chloride;

[0032] The gas is vacuum filtered and condensed to obtain the recovered DMAC solvent.

[0033] As a preferred technical solution of the present invention, the drying method includes heating drying and / or heat exchange drying.

[0034] As a preferred technical solution of the present invention, the drying operating temperature is 90-95°C.

[0035] Preferably, the drying time is 3-4 hours.

[0036] As a preferred technical solution of the present invention, the mass concentration of ammonium chloride in the mixed solution is 35-36%.

[0037] Preferably, the precision of the solid-liquid separation is 5-50 μm.

[0038] Preferably, the mass concentration of ammonium chloride in the concentrated solution obtained by the concentration is 37-38%.

[0039] As a preferred technical solution of the present invention, the crystallization includes at least two levels of crystallization.

[0040] Preferably, the crystallization temperature is 5-10°C.

[0041] Preferably, the cooling rate of the crystallization is 0.1-0.3°C / min.

[0042] Preferably, the pH value of the crystallization is 6-7.

[0043] As a preferred technical solution of the present invention, the absolute vacuum degree in the vacuum filtration is 90-99 kPa.

[0044] Preferably, the condensation temperature is 20-35°C.

[0045] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0046] (1) The device provided by the present invention has the advantages of high degree of automation control, low labor intensity, low energy consumption, low equipment corrosion, long service life, environmental protection and good working environment.

[0047] (2) When the device provided by the present invention is used to recycle meta-aramid polymerization by-products, the recovery rate of the solvent DMAC is ≥99%, and the recovered ammonium chloride can meet the quality standard of industrial ammonium chloride in "Ammonium Chloride" (GB / T2946-2018). BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of a comprehensive recovery device for meta-aramid polymerization by-products provided by the present invention.

[0049] In the figure: 1-drying equipment, 2-gas-solid separation equipment, 3-condensing equipment, 4-solvent recovery tank, 5-solvent delivery pump group, 6-vacuum buffer tank, 7-vacuum pump group, 8-emptying receiving tank, 9-mixing equipment, 10-solid-liquid separation equipment, 11-concentration equipment, 12-crystallization equipment, 13-dehydration equipment;

[0050] I-meta-aramid polymerization by-product, II-purge gas, III-cooling circulating water, IV-tail gas elution end, V-solvent secondary utilization end, VI-drying inlet heat medium, VII-drying outlet heat medium, VIII-purified ammonium chloride.

[0051] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0052] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0053] This embodiment provides a comprehensive recovery device for meta-aramid polymerization by-products, such as Figure 1 As shown, the comprehensive recovery device comprises:

[0054] Drying equipment 1, gas-solid separation equipment 2, condensation equipment 3, solvent recovery tank 4, vacuum buffer tank 6, solvent delivery pump group 5;

[0055] The gas phase outlet of the drying device 1 is connected to the condensation device 3 through the gas-solid separation device 2;

[0056] The gas phase outlet of the condensing device 3 is connected to the vacuum buffer tank 6;

[0057] The condensing device 3 or the vacuum buffer tank 6 is connected to a vacuum pump group 7;

[0058] The liquid phase outlet of the condensing device 3 is connected to the solvent recovery tank 4;

[0059] The solvent recovery tank 4 is connected to the solvent secondary utilization end through the solvent delivery pump group 5;

[0060] The solid phase outlet of the drying device 1 is sequentially connected to a mixing device 9, a solid-liquid separation device 10, a concentration device 11, a crystallization device 12 and a dehydration device 13.

[0061] In the present invention, the meta-aramid polymerization byproducts include, by weight percentage, 60-70% ammonium chloride, 20-30% DMAC solvent, and 1-3% oligomer.

[0062] Specifically, the drying device 1 comprises a heating jacket and / or a hollow heating rake.

[0063] Specifically, the hollow heating rake is equipped with a transmission device.

[0064] In the present invention, the drying device 1 of the present invention is used to indirectly heat the meta-aramid polymerization byproduct I through the heat medium in its jacket and hollow shaft rake teeth (drying inlet heat medium VI, drying outlet heat medium VII), the ammonium chloride mixture in the meta-aramid polymerization byproduct I is evaporated by conduction, the agitator with a scraper continuously removes the material on the hot surface, and pushes in the container to form a circulating flow, wherein the DMAC solvent is extracted by a vacuum pump after evaporation; the dried ammonium chloride mixture is added from the feed port above the cylinder, and under the stirring of the continuously rotating rake teeth, when the material contacts the inner wall of the cylinder, the surface is continuously renewed, and the dried material is indirectly heated by hot water, so that the solvent component in the material is vaporized, and the vaporized DMAC solvent component is promptly extracted by the vacuum pump group 7, because the operating vacuum degree is high, it is beneficial to the discharge of the internal moisture and surface moisture of the dried material, and it is beneficial to the movement of wet molecules of the dried material, so as to achieve the purpose of drying.

[0065] In the present invention, the drying device 1 is exemplarily provided with a cylinder, an inlet and outlet, a hot water inlet and outlet, a transmission system, a worm gear quick-release discharge valve, etc.; it is further explained that the interior of the stirring shaft is a hollow structure, and hot water can be introduced to increase the heat transfer area, thereby improving the drying and separation effect of wet material ammonium chloride; it is further explained that the motor auxiliary device is a variable frequency type, and the wet material ammonium chloride and the heating surface can be continuously updated by adjusting the speed, thereby improving the drying and separation effect of ammonium chloride. The vacuum dryer has a compact structure, a small footprint, good sealing effect, and a large vacuum degree.

[0066] In the present invention, the gas-solid separation device 2 can be preferably arranged on the top of the drying device 1 to filter out large particles of the intercepted suction material, and the type can be selected to be a filter bag.

[0067] For example, the filter bag has a length of 0.5-3m, a diameter of 100-300mm, and a filtration accuracy of 5-50μm; the vacuum filter is connected to the purge system, and the purge gas II is used to purge the attachments intercepted and filtered on the surface of the filter bag to increase the service life of the filter bag and ensure the filtration effect; the purge system is equipped with an automatic switch valve for easy operation. The filter bag size, filtration accuracy, and nitrogen purge pressure are not limited to the above data and can be adjusted according to the specific operation of the equipment.

[0068] Specifically, the solvent recovery tank 4 is connected to an emptying receiving tank 8 .

[0069] Furthermore, during the drying process of the meta-aramid polymerization byproduct, the DMAC component is quickly heated and vaporized, filtered by the gas-solid separation device 2, and then led to the condenser through a pipeline, where the DMAC component is condensed and liquefied, and discharged from the bottom of the condenser to the solvent recovery tank for recycling, and the DMAC solvent accumulated in the vacuum buffer tank 6 will also be regularly discharged into the recovery tank. The non-condensable gas discharged from the vacuum dryer is discharged to the factory area through the vacuum buffer tank 6 and the vacuum pump and enters the waste gas treatment system.

[0070] In the present invention, the condensing device 3 used can be selected as a water-cooled condenser, which can be divided into a shell and tube type or a sleeve and tube type. The condenser is provided with a circulating water inlet and outlet for circulating cooling circulating water III.

[0071] In the present invention, the solvent recovery tank 4 is used to receive the DMAC solvent component recovered by condensation, and is located below the condenser. The solvent recovery tank 4 is equipped with auxiliary facilities such as a liquid level gauge, a delivery pump, and an emptying valve. The delivery pump cooperates with the liquid level gauge for control. When the liquid level reaches a high value, the delivery pump automatically starts to deliver to the solvent secondary utilization terminal V. When the low liquid level is reached, the pump automatically stops, and the automatic control facilitates operation.

[0072] In the present invention, the vacuum buffer tank 6 is mainly used for buffering pressure, preventing backflow, gas-liquid separation and stabilizing vacuum degree, and is provided with auxiliary facilities such as a pressure gauge, a safety valve, a liquid level indicator, and a drain valve.

[0073] In the present invention, the vacuum pump group 7 is used for negative pressure suction of evaporated DMAC solvent components, and a tail gas absorption system is provided in conjunction with the tail gas suction of the vacuum pump group 7. The tail gas sucked by the vacuum pump group 7 enters the tail gas washing end IV for further absorption, meeting the requirements of environmental protection standards.

[0074] Specifically, the heat medium outlet of the drying device 1 is connected to the heat medium inlet of the dehydration device 13 .

[0075] Specifically, the crystallization device 12 includes at least two stages of crystallization devices.

[0076] Specifically, the gas phase condensate outlet of the concentration device 11 is connected to the liquid inlet of the mixing device 9 .

[0077] Specifically, the heat medium outlet of the dehydration device 13 is connected to the heat medium inlet of the concentration device 11 .

[0078] In the present invention, the dehydration device and the concentration device may preferably use the hot water return water of the drying device as the heating medium.

[0079] In the present invention, the dried crude ammonium chloride mixture is conveyed into the mixing device 9 via a screw conveyor, and desalted water at 60-90° C. can be selectively introduced into the mixing device 9 for dissolution, and a stirring device is provided in the mixing device 9 to accelerate the dissolution effect. At the same time, the temperature of the desalted water in the mixing device 9 can be adjusted according to the different solubility of ammonium chloride (crude ammonium chloride: ammonium chloride content ≥ 98.5%, other components include trace amounts of DMAC solvent and oligomers).

[0080] In the present invention, the concentration device 11 performs evaporation and concentration to remove the water contained in the material, and the heat medium in its jacket can be heated by hot water return water from the dehydration device 13 to save costs. In order to improve efficiency, the evaporation concentrator is operated under negative pressure, and the condensed water sucked by the concentration device 11 can also be used for mixing in the mixing device 9.

[0081] In the present invention, the saturated ammonium chloride liquid after evaporation and concentration is metered and transported to the crystallization device 12 by a pump. A plurality of crystallization devices 12 can be used in series. The crystallization device 12 is not limited to two. The purpose is to ensure sufficient crystallization and separation of ammonium chloride. In order to improve the crystallization effect and save costs, the next-stage crystallization device 12 can be fed with 5-15°C low-temperature chilled water, and the cold water outlet of the crystallization device 12 can be selected to enter the previous-stage crystallization device 12 for cooling and crystallization recycling.

[0082] In the present invention, the crystallized ammonium chloride needs to be further dehydrated by a dehydration device 13 to remove the water contained therein in order to meet the requirements of downstream customers for water content, and then output the purified ammonium chloride VIII. In order to prevent the decomposition of ammonium chloride and save costs, the operating temperature of the dehydration device 13 is ≤100°C, and the outlet hot water of the drying device can be used to heat it to remove excess water. The dehydration device 13 is operated under negative pressure, and its condensed water can be used to supplement the mixing device 9.

[0083] Furthermore, the present invention provides a comprehensive recovery method for meta-aramid polymerization byproducts, comprising:

[0084] feeding the meta-aramid polymerization byproduct into a drying device for drying to obtain crude ammonium chloride and gas;

[0085] The crude ammonium chloride is mixed, solid-liquid separated, concentrated and crystallized to obtain purified ammonium chloride;

[0086] The gas is vacuum filtered and condensed to obtain the recovered DMAC solvent.

[0087] Wherein, the drying method includes heating drying and / or heat exchange drying.

[0088] Among them, the drying operating temperature is 90-95°C, for example, it can be 90°C, 90.5°C, 91°C, 91.5°C, 92°C, 92.5°C, 93°C, 93.5°C, 94°C, 94.5°C or 95°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0089] In the present invention, when the heat exchange drying method is adopted, hot water is introduced into the jacket and the center of the rotating shaft of the drying equipment to increase the heat transfer area and improve the drying and separation effect of ammonium chloride and the solvent DMAC. After indirect contact heat transfer with ammonium chloride, the return water temperature is 80-85°C, for example, it can be 80°C, 80.5°C, 81°C, 81.5°C, 82°C, 82.5°C, 83°C, 83.5°C, 84°C, 84.5°C or 85°C, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0090] The drying time is 3-4h, for example, 3h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h, 3.6h, 3.7h, 3.8h, 3.9h or 4h, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0091] The mass concentration of ammonium chloride in the mixed solution is 35-36%, for example, 35%, 35.1%, 35.2%, 35.3%, 35.4%, 35.5%, 35.6%, 35.7%, 35.8%, 35.9% or 36%, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0092] Wherein, the precision of solid-liquid separation is 5-50 μm.

[0093] The mass concentration of ammonium chloride in the concentrated solution obtained by the concentration is 37-38%, for example, it can be 37%, 37.1%, 37.2%, 37.3%, 37.4%, 37.5%, 37.6%, 37.7%, 37.8%, 37.9% or 38%, etc., but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0094] Wherein, the crystallization includes at least 2 levels of crystallization.

[0095] Wherein, the crystallization temperature is 5-10°C, for example, it can be 5°C, 5.5°C, 6°C, 6.5°C, 7°C, 7.5°C, 8°C, 8.5°C, 9°C, 9.5°C or 10°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0096] Wherein, the cooling rate of the crystallization is 0.1-0.3°C / min, for example, it can be 0.1°C / min, 0.12°C / min, 0.14°C / min, 0.16°C / min, 0.18°C / min, 0.2°C / min, 0.24°C / min, 0.26°C / min, 0.28°C / min or 0.3°C / min, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0097] The pH value of the crystallization is 6-7, for example, 6, 6.2, 6.4, 6.6, 6.8 or 7, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0098] Among them, the absolute vacuum degree in the vacuum filtration is 90-99kPa, for example, it can be 90kPa, 91kPa, 92kPa, 93kPa, 94kPa, 95kPa, 96kPa, 97kPa, 98kPa or 99kPa, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0099] Wherein, the condensation temperature is 20-35°C, for example, it can be 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C or 35°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0100] In the present invention, the condensation temperature refers to the temperature of the condensation medium such as water used in the condensation process.

[0101] Further, in order to illustrate the good recovery effect that can be achieved by the comprehensive recovery device for meta-aramid polymerization byproducts provided by the present invention, the following actual example is used for illustration, as follows:

[0102] Example 1

[0103] This embodiment provides a specific recovery process of meta-aramid polymerization byproducts, which is as follows:

[0104] feeding the meta-aramid polymerization byproduct into a drying device for drying to obtain crude ammonium chloride and gas;

[0105] The crude ammonium chloride is mixed, solid-liquid separated, concentrated and crystallized to obtain purified ammonium chloride;

[0106] The gas is vacuum filtered and condensed to obtain a recovered DMAC solvent;

[0107] The drying operation temperature is 94°C; the drying time is 3.5 hours;

[0108] The mass concentration of ammonium chloride in the mixed solution is 35.7%; the precision of the solid-liquid separation is 30 μm; the mass concentration of ammonium chloride in the concentrated solution obtained by concentration is 37.3%; the crystallization is a three-stage crystallization; the crystallization temperature is 8°C; the cooling rate of the crystallization is 0.15°C / min; the pH value of the crystallization is 6.8;

[0109] The absolute vacuum degree in the vacuum filtration is 98.8 kPa;

[0110] The condensation temperature was 30°C.

[0111] The indicators of the recovered products are shown in Table 1.

[0112] Example 2

[0113] This embodiment provides a specific recovery process of meta-aramid polymerization byproducts, which is as follows:

[0114] feeding the meta-aramid polymerization byproduct into a drying device for drying to obtain crude ammonium chloride and gas;

[0115] The crude ammonium chloride is mixed, solid-liquid separated, concentrated and crystallized to obtain purified ammonium chloride;

[0116] The gas is vacuum filtered and condensed to obtain a recovered DMAC solvent;

[0117] The drying operation temperature is 92°C; the drying time is 3.8h;

[0118] The mass concentration of ammonium chloride in the mixed solution is 35.5%; the precision of the solid-liquid separation is 20 μm; the mass concentration of ammonium chloride in the concentrated solution obtained by concentration is 37.5%; the crystallization is a second-stage crystallization; the crystallization temperature is 6°C; the cooling rate of the crystallization is 0.2°C / min; the pH value of the crystallization is 6.5;

[0119] The absolute vacuum degree in the vacuum filtration is 98.5 kPa;

[0120] The condensation temperature was 32°C.

[0121] The indicators of the recovered products are shown in Table 1.

[0122] Example 3

[0123] This embodiment provides a specific recovery process of meta-aramid polymerization byproducts, which is as follows:

[0124] feeding the meta-aramid polymerization byproduct into a drying device for drying to obtain crude ammonium chloride and gas;

[0125] The crude ammonium chloride is mixed, solid-liquid separated, concentrated and crystallized to obtain purified ammonium chloride;

[0126] The gas is vacuum filtered and condensed to obtain a recovered DMAC solvent;

[0127] The drying operation temperature is 90°C; the drying time is 4 hours;

[0128] The mass concentration of ammonium chloride in the mixed solution is 35%; the precision of the solid-liquid separation is 50 μm; the mass concentration of ammonium chloride in the concentrated solution obtained by concentration is 38%; the crystallization includes at least 2 stages of crystallization; the crystallization temperature is 5°C; the cooling rate of the crystallization is 0.1°C / min; the pH value of the crystallization is 6; the absolute vacuum degree in the vacuum filtration is 98 kPa;

[0129] The condensation temperature was 35°C.

[0130] The indicators of the recovered products are shown in Table 1.

[0131] Example 4

[0132] This embodiment provides a specific recovery process of meta-aramid polymerization byproducts, which is as follows:

[0133] feeding the meta-aramid polymerization byproduct into a drying device for drying to obtain crude ammonium chloride and gas;

[0134] The crude ammonium chloride is mixed, solid-liquid separated, concentrated and crystallized to obtain purified ammonium chloride;

[0135] The gas is vacuum filtered and condensed to obtain a recovered DMAC solvent;

[0136] The drying operation temperature is 95°C; the drying time is 3h;

[0137] The mass concentration of ammonium chloride in the mixed solution is 36%; the precision of the solid-liquid separation is 10 μm; the mass concentration of ammonium chloride in the concentrated solution obtained by concentration is 37%; the crystallization includes at least 2 stages of crystallization; the crystallization temperature is 10°C; the cooling rate of the crystallization is 0.15°C / min; the pH value of the crystallization is 7; the absolute vacuum degree in the vacuum filtration is 99 kPa;

[0138] The temperature of the condensation was 31°C.

[0139] The indicators of the recovered products are shown in Table 1.

[0140] Table 1

[0141] Moisture content of crude ammonium chloride / % Solvent recovery rate / % Purified salt purity / % Example 1 1.1 99.7 99.6 Example 2 1.2 99.6 99.5 Example 3 1.5 99.5 99.8 Example 4 0.8 99.8 99.7

[0142] As can be seen from Table 1, the comprehensive recovery device provided by the present invention realizes the efficient recovery of ammonium salt and solvent DMAC in the meta-aramid polymerization by-products, which is beneficial to the resource utilization of the meta-aramid polymerization by-products, thereby improving the utilization rate of related materials, and is beneficial to the green and sustainable development of meta-aramid polymerization.

[0143] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0144] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0145] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A comprehensive recovery device for meta-aramid polymerization by-products, characterized in that: The comprehensive recovery device comprises: Drying equipment, gas-solid separation equipment, condensation equipment, solvent recovery tank, vacuum buffer tank, solvent delivery pump set; The gas phase outlet of the drying device is connected to the condensing device through the gas-solid separation device; The gas phase outlet of the condensing device is connected to the vacuum buffer tank; The condensing device or the vacuum buffer tank is connected to a vacuum pump group; The liquid phase outlet of the condensing device is connected to the solvent recovery tank; The solvent recovery tank is connected to the solvent secondary utilization end through a solvent delivery pump group; The solid phase outlet of the drying device is sequentially connected with a mixing device, a solid-liquid separation device, a concentration device, a crystallization device and a dehydration device.

2. The comprehensive recovery device according to claim 1, characterized in that: The drying equipment includes a heating jacket and / or a hollow heating rake; Preferably, the hollow heating rake is provided with a transmission device.

3. The comprehensive recovery device according to claim 1, characterized in that: The solvent recovery tank is connected to an emptying receiving tank.

4. The comprehensive recovery device according to claim 1, characterized in that: The heat medium outlet of the drying device is connected to the heat medium inlet of the dehydration device; Preferably, the crystallization device comprises at least 2 stages of crystallization devices; Preferably, the gas phase condensate outlet of the concentration device is connected to the liquid inlet of the mixing device; Preferably, the heat medium outlet of the dehydration device is connected to the heat medium inlet of the concentration device.

5. A comprehensive recovery method for meta-aramid polymerization by-products, characterized in that: The comprehensive recovery method comprises: feeding the meta-aramid polymerization byproduct into a drying device for drying to obtain crude ammonium chloride and gas; The crude ammonium chloride is mixed, solid-liquid separated, concentrated and crystallized to obtain purified ammonium chloride; The gas is vacuum filtered and condensed to obtain the recovered DMAC solvent.

6. The comprehensive recovery method according to claim 5, characterized in that: The drying method includes heating drying and / or heat exchange drying.

7. The comprehensive recovery method according to claim 5, characterized in that: The drying operating temperature is 90-95°C; Preferably, the drying time is 3-4 hours.

8. The comprehensive recovery method according to claim 5, characterized in that: The mass concentration of ammonium chloride in the mixed solution is 35-36%; Preferably, the precision of the solid-liquid separation is 5-50 μm; Preferably, the mass concentration of ammonium chloride in the concentrated solution obtained by the concentration is 37-38%.

9. The comprehensive recovery method according to claim 5, characterized in that: The crystallization comprises at least 2 levels of crystallization; Preferably, the crystallization temperature is 5-10°C; Preferably, the cooling rate of the crystallization is 0.1-0.3°C / min; Preferably, the pH value of the crystallization is 6-7.

10. The comprehensive recovery method according to claim 5, characterized in that: The absolute vacuum degree in the vacuum filtration is 90-99 kPa; Preferably, the condensation temperature is 20-35°C.

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