CN215138669U - NMP pervaporation dewatering device - Google Patents
NMP pervaporation dewatering device Download PDFInfo
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- CN215138669U CN215138669U CN202022743396.2U CN202022743396U CN215138669U CN 215138669 U CN215138669 U CN 215138669U CN 202022743396 U CN202022743396 U CN 202022743396U CN 215138669 U CN215138669 U CN 215138669U
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Abstract
The invention provides an NMP pervaporation dehydration device, which comprises a raw material processing unit, a membrane separation unit and a permeate processing unit, wherein: the raw material processing unit comprises first heat exchange equipment, a first storage tank and a second storage tank; wherein the membrane separation unit is provided with a material inlet, a retentate outlet and a permeate outlet; the retentate outlet of the membrane separation unit is connected with a second storage tank; and the permeate outlet of the membrane separation unit is connected with the permeate treatment unit. The device and the method based on the molecular sieve membrane separation technology carry out deep dehydration on the water-containing NMP, and at least two stages of steam permeable membrane devices are adopted to realize the deep dehydration on the NMP; and the intermittent or continuous dehydration operation mode can be flexibly selected according to the different treatment capacity and the water content of the waste NMP solvent, the switching is flexible, and the operation is convenient.
Description
Technical Field
The invention relates to the field of high-purity NMP production, in particular to a NMP pervaporation dehydration device.
Background
NMP is an abbreviation for N-methylpyrrolidone. N-methyl pyrrolidone (NMP) is an organic solvent and has the advantages of low toxicity, high boiling point, difficult volatilization, strong solubility, stable chemical property and the like. The high-purity NMP product is widely used in the industries of lithium batteries, carbon nano tube conductive paste, liquid crystal electronics, semiconductors, insulating materials and the like. With the rising and rapid development of the lithium battery industry, the demand of high-purity NMP in the fields of power batteries, energy storage batteries and the like is increasing day by day. In the production process of lithium batteries, high-purity NMP greatly affects the quality and effect of coating and the improvement of energy density of lithium batteries. In the blending stage, the PVDF solution is used as a PVDF solvent and can keep stable slurry in a certain viscosity range; in the coating stage, the coating material is used as a main liquid carrier of the slurry and has very good wettability and fluidity; in the coating and baking stage, the coating and baking liquid is volatilized from the wet film at a stable speed to form a porous microelectrode structure with uniform pore size and distribution.
The quality of NMP is mainly influenced by key indexes such as purity, moisture and metal ions. Lithium batteries have strict limits on the purity of NMP, especially on the water content, which is required to be less than 0.02% or even lower. At present, the water content of domestic NMP is generally more than 0.03 percent, and the requirements of the lithium battery industry are difficult to meet.
Pervaporation, including vapor permeation, is a novel membrane technology for the separation of gas (liquid) mixtures, where components permeate the membrane layer by diffusion, driven by the pressure difference between the components across the membrane, and vaporize to vapor on the permeate side. The pervaporation membrane has high efficiency, can realize high separation degree in a single stage, has low energy consumption, and can save energy consumption by 1/2-2/3 compared with the rectification process. Meanwhile, the process is simple, excessive matching treatment is not needed, the system is reliable and high in stability, other components are not introduced in the separation process, and the method belongs to an environment-friendly technology.
Disclosure of Invention
The invention aims to provide a set of NMP pervaporation dehydration device and discloses a method for dehydrating and refining NMP based on the NMP pervaporation dehydration device.
In order to achieve the purpose, the invention firstly provides a set of NMP pervaporation dehydration device, which comprises a raw material processing unit, a membrane separation unit and a permeate processing unit, wherein: the raw material processing unit comprises first heat exchange equipment, a first storage tank and a second storage tank; wherein the membrane separation unit is provided with a material inlet, a retentate outlet and a permeate outlet; the retentate outlet of the membrane separation unit is connected with a second storage tank; and the permeate outlet of the membrane separation unit is connected with the permeate treatment unit.
In another aspect, the present invention provides a method for pervaporation dehydration of NMP using the above apparatus for pervaporation dehydration of NMP, comprising: preheating a water-containing NMP raw material at a mass flow rate of 1200 +/-100 kg/batch, then feeding the preheated water-containing NMP raw material into a first storage tank, feeding the buffered raw material into a membrane separation unit for primary dehydration, and feeding a permeate into a permeate treatment unit; and (3) enabling the retentate obtained by the primary dehydration to enter a second storage tank, continuously and circularly conveying the retentate to a membrane separation unit for secondary dehydration, enabling the retentate obtained by the secondary dehydration to enter a first storage tank, and extracting an NMP product when the water content of the retentate is detected to meet the product requirement.
The invention adopts a device and a method based on molecular sieve membrane separation technology to carry out deep dehydration on the water-containing NMP, and adopts at least two stages of steam permeable membrane devices to realize the deep dehydration on the NMP; and the intermittent or continuous dehydration operation mode can be flexibly selected according to the different treatment capacity and the water content of the waste NMP solvent, the switching is flexible, and the operation is convenient.
Drawings
FIG. 1 is a diagram of an apparatus for pervaporation dehydration of NMP according to the present invention, wherein:
1. a first heat exchange device; 2. a first storage tank; 3. a second storage tank; 4. a first fluid delivery device; 5. a second heat exchange device; 6. a first membrane separation module; 7. a second membrane separation module; 8. a permeate processing apparatus; 9. a third storage tank; 10. a second fluid delivery device.
Detailed Description
The following detailed description of the invention refers to the accompanying drawings.
The NMP pervaporation dehydration device comprises a raw material processing unit, a membrane separation unit and a permeate processing unit, wherein a water-containing NMP raw material to be processed enters the membrane separation unit through the raw material processing unit for dehydration, and water molecules penetrate through a molecular sieve membrane to form a permeate which enters the permeate processing unit. NMP with larger molecular size is intercepted by the molecular sieve membrane to form NMP product with ultra-low water content.
In a specific embodiment, the method comprises a raw material processing unit, a membrane separation unit and a permeate processing unit, wherein: the raw material processing unit comprises a first heat exchange device 1, a first storage tank 2 and a second storage tank 3; the membrane separation unit comprises a first membrane separation assembly 6 and a second membrane separation assembly 7; a first fluid conveying device 4 and a second heat exchange device 5 are also arranged between the raw material processing unit and the membrane separation unit; the permeate processing unit comprises a permeate processing device 8, a third storage tank 9 and a second fluid conveying device 10; wherein the membrane separation unit is provided with a material inlet, a retentate outlet and a permeate outlet; the retentate outlet of the membrane separation unit is connected with a second storage tank 3; the permeate outlet of the membrane separation unit is connected with the permeate treatment unit; the material outlet of the second storage tank 3 is connected with a first fluid conveying device 4.
In the above NMP pervaporation dehydration apparatus of the present invention:
the first heat exchange device 1 provides a site for preheating the feedstock. According to the process requirements, the first heat exchange device 1 can be selected from, but not limited to, a fixed tube-plate type tube-and-tube heat exchanger, a floating head type tube-and-tube heat exchanger, a U-shaped tube-and-tube heat exchanger, a spiral plate type heat exchanger, a spiral tube wound heat exchanger and a plate type heat exchanger.
The first storage tank 2 is used for buffer storage of the water-containing NMP raw material.
The second reservoir 3 is used for buffer storage of the retentate.
The first fluid transfer means 4 is adapted to transfer the aqueous feed to a membrane separation unit, which may be selected from, but is not limited to, a centrifugal pump, a positive displacement pump.
The second heat exchange means 5 is adapted to receive and heat exchange the aqueous NMP feedstock from the feedstock treatment unit. The second heat exchanger 5 can be selected from, but not limited to, a fixed tube-plate type tube-and-tube heat exchanger, a floating head type tube-and-tube heat exchanger, a U-shaped tube-and-tube heat exchanger, a spiral plate type heat exchanger, a spiral tube wound heat exchanger, and a plate type heat exchanger.
The membrane separation unit is used for realizing efficient separation of NMP and water. For realizing the purpose, the membrane separation unit is preferably an inorganic molecular sieve membrane separation unit and consists of n (n is a positive integer) molecular sieve membrane assemblies. The membrane assembly can be a single tube pass or a plurality of tube passes, and the area of the single membrane assembly can be controlled between 5 square meters and 300 square meters. The number n of membrane modules arranged in each set is determined according to the separation purpose; when n is greater than 1, the membrane modules can be connected in series or in parallel according to the material condition, the separation target and the like. On the other hand, from the component structure, the present invention can adopt, but is not limited to, specific forms such as a thermostatic membrane component or a baffle-type membrane component. In the embodiment of the present invention, the molecular sieve membrane module may be specifically exemplified by, but not limited to, a plate-type, tubular-type, hollow fiber-type or spiral plate-type molecular sieve membrane module, preferably a tubular-type molecular sieve membrane module. Suitable types of molecular sieves include LTA, SOD, FAU, MOR, FER, MFI, PHI, BEA, CHA, ERI, and mixed crystal molecular sieve membranes thereof, preferably type A molecular sieve membranes.
The permeate processing means 8 is arranged to receive the permeate from the membrane separation unit and to further process it. The permeate processing equipment 8 can be selected from, but is not limited to, a vacuum unit with steam condensation recovery.
The third storage tank 9 is a permeate buffer tank, and is output by the second fluid conveying device 10 after being buffered. The second fluid transfer device 10 may be exemplified by, but not limited to, a centrifugal pump, a positive displacement pump.
In the structural description of the above-mentioned device, the components that can be determined by those skilled in the art through the prior art in this field are not described, and these components can be exemplified but not limited to: the pipeline is used for connecting each device, and the valve is used for controlling the material to enter and exit. In addition, in combination with the above description, those skilled in the art can determine the most appropriate device selection and type according to the design requirements and requirements under the guidance of the prior art, and it is needless to describe this.
In another aspect, the present invention provides a method for dehydrating NMP by pervaporation, the method using the above apparatus of the present invention, comprising the steps of:
(1) an NMP raw material with the water content of 1-20% is preheated to 120 +/-10 ℃ through a first heat exchange device 1 at the mass flow rate of 1200 +/-100 kg/batch, enters a first storage tank 2 for buffering, is conveyed to a first membrane separation assembly 6 and a second membrane separation assembly 7 through a first fluid conveying device 4 and a second heat exchange device 5 at the temperature of 120 +/-2 ℃ for primary dehydration, and enters a third storage tank 9 after passing through a permeate treatment device 8, and is discharged out of the system through the second fluid conveying device 10;
(2) conveying the retentate after primary dehydration to a second storage tank 3, and continuously circularly conveying the retentate to a membrane separation unit by a first fluid conveying device 4 for secondary dehydration; transferring the retentate after the secondary dehydration to a first storage tank 2, and circulating the steps; the cumulative mass flow rate of permeate was 180 ± 15 kg/batch with a total water content of greater than 99.5%; and when the water content of the retentate meets the product requirement, collecting the retentate to be an NMP product.
The contents and effects of the present invention will be further described with reference to the following examples, but the present invention should not be construed as being limited to the contents in any form. In this example, the method described herein uses an NMP pervaporation dehydration apparatus as illustrated in fig. 1, and the selection of the equipment in the apparatus is as follows:
the first heat exchange device 1 is a fixed tube-plate type tubular heat exchanger.
The first storage tank 2 is a first buffer tank.
The second storage tank 3 is a second buffer tank.
The first fluid conveying device 4 is a centrifugal pump.
The second heat exchange device 5 is a fixed tube-plate type tubular heat exchanger.
The first membrane separation component 6 is a tubular molecular sieve membrane component; the molecular sieve membrane is an A-type molecular sieve membrane.
The second membrane separation component 7 is a tubular molecular sieve membrane component; the molecular sieve membrane is an A-type molecular sieve membrane.
And the permeate buffer tank 8 adopts a vacuum unit with steam condensation and recovery.
The third storage tank 9 is a permeate buffer tank.
The second fluid transfer device 10 is a centrifugal pump.
The method for the pervaporation dehydration of NMP, which is implemented by combining the device, comprises the following steps:
(1) the waste solvent NMP raw material from the coating section of a lithium battery production workshop, which contains 15% of water and a small amount of alkanone high-boiling point impurities, is preheated to 120 ℃ through a fixed tube plate type tube and tube heat exchanger 1 at a mass flow rate of 1200 kg/batch, enters a first buffer tank 2 for buffering, is conveyed to enter a tubular molecular sieve membrane assembly 6 and a tubular molecular sieve membrane assembly 7 through a centrifugal pump 4 and a fixed tube plate type tube and tube heat exchanger 5 at a temperature of 120 ℃ (the total membrane area of selected molecular sieve membranes is 72m2) Performing primary dehydration, treating the permeate by a vacuum unit 8 with steam condensation recovery, then entering a permeate buffer tank 9, and discharging the permeate from the system by a centrifugal pump 10;
(2) conveying the retentate after primary dehydration to a second buffer tank 3, continuously and circularly conveying the retentate to a membrane separation unit by a centrifugal pump 4 for secondary dehydration, and conveying the retentate after secondary dehydration into a first buffer tank 2 for circulating the steps; the cumulative mass flow rate of permeate was 180 kg/batch with a total water content of greater than 99.5%; when the water content of the retentate is detected to be less than 180ppm, an NMP product is extracted;
through the treatment of the device, the NMP mass concentration in the obtained permeate is less than 1%, and the NMP recovery rate in the whole process is more than 99%. At the same time, the steam consumption per ton of NMP product was about 0.15 ton.
Claims (6)
1. The NMP pervaporation dehydration device is characterized by comprising a raw material processing unit, a membrane separation unit and a permeate processing unit, wherein: the raw material processing unit comprises a first heat exchange device (1), a first storage tank (2) and a second storage tank (3);
wherein the membrane separation unit is provided with a material inlet, a retentate outlet and a permeate outlet; the retentate outlet of the membrane separation unit is connected with a second storage tank (3);
and the permeate outlet of the membrane separation unit is connected with the permeate treatment unit.
2. A pervaporation dewatering apparatus for NMP according to claim 1 characterised in that a first fluid transfer means (4) and a second heat exchange means (5) are provided between said feed treatment unit and said membrane separation unit.
3. A pervaporation dewatering device for NMP according to claim 1, characterised in that said membrane separation unit comprises a first membrane separation module (6) and a second membrane separation module (7).
4. A pervaporation dewatering arrangement according to claim 1, characterised in that said permeate handling unit comprises permeate handling means (8), third reservoir (9) and second fluid transfer means (10).
5. A NMP pervaporation dewatering device according to claim 1, characterised in that the material outlet of the second reservoir (3) is connected to the first fluid transfer means (4).
6. A pervaporation dehydration apparatus for NMP according to claim 1, comprising a raw material processing unit, a membrane separation unit and a permeate processing unit, wherein: the raw material processing unit comprises a first heat exchange device (1), a first storage tank (2) and a second storage tank (3); the membrane separation unit comprises a first membrane separation assembly (6) and a second membrane separation assembly (7); a first fluid conveying device (4) and a second heat exchange device (5) are arranged between the raw material processing unit and the membrane separation unit; the permeate treatment unit comprises a permeate treatment device (8), a third storage tank (9) and a second fluid conveying device (10);
wherein the membrane separation unit is provided with a material inlet, a retentate outlet and a permeate outlet; the retentate outlet of the membrane separation unit is connected with a second storage tank (3); the permeate outlet of the membrane separation unit is connected with the permeate treatment unit;
the material outlet of the second storage tank (3) is connected with a first fluid conveying device (4).
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| Application Number | Priority Date | Filing Date | Title |
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| CN202022743396.2U CN215138669U (en) | 2020-11-24 | 2020-11-24 | NMP pervaporation dewatering device |
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| CN202022743396.2U CN215138669U (en) | 2020-11-24 | 2020-11-24 | NMP pervaporation dewatering device |
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| CN215138669U true CN215138669U (en) | 2021-12-14 |
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