CN106831526B - Device and method for recovering and purifying N-methyl pyrrolidone - Google Patents
Device and method for recovering and purifying N-methyl pyrrolidone Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D207/00—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom
- C07D207/02—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D207/18—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having one double bond between ring members or between a ring member and a non-ring member
- C07D207/22—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having one double bond between ring members or between a ring member and a non-ring member with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D207/24—Oxygen or sulfur atoms
- C07D207/26—2-Pyrrolidones
- C07D207/263—2-Pyrrolidones with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to other ring carbon atoms
- C07D207/267—2-Pyrrolidones with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to other ring carbon atoms with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to the ring nitrogen atom
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Abstract
The application provides a device and a method for recovering and purifying N-methyl pyrrolidone, at least three stages of circulating cooling devices are arranged to obtain absorption liquid containing high-concentration N-methyl pyrrolidone and reach the tail gas emission standard, and a cooler of each stage of circulating cooling device can also control the absorption temperature and increase the absorption effect. The product is directly extracted from the tower kettle to obtain a high-purity N-methyl pyrrolidone product, and the waste water at the tower top is directly and repeatedly absorbed and utilized to increase the yield of the N-methyl pyrrolidone and avoid the treatment cost.
Description
Technical Field
The invention relates to the technical field of chemical industry, in particular to a device and a method for recovering and purifying N-methyl pyrrolidone.
Background
The lithium battery industry is developing at a high rate under the background of a strong demand for clean energy. When the lithium battery is manufactured, a layer of polymer needs to be coated on the positive electrode and the negative electrode of the battery, the polymer needs to be coated on the surface of an electrode plate after being dissolved by an organic solvent, and then the organic solvent is separated from the positive electrode and the negative electrode plate after drying treatment. Because NMP (N-methyl pyrrolidone) has the advantages of high flash point, good thermal stability, good safety, good solubility and the like, NMP is generally used as an organic solvent in the lithium battery manufacturing industry. However, during use, NMP will gasify with the dry tail gas exiting. With the increasing national environmental protection requirements, it is an inevitable trend to effectively recover and recycle NMP in the tail gas.
The traditional method for recovering NMP in tail gas mainly comprises an adsorption method, a multistage condensation method and a spraying method, wherein the adsorption method is used for separating NMP in tail gas through different polarities of an adsorbent and a medium, and has the characteristics of high absorption rate, high recovery rate and the like, but the cost is high due to the quantitative loss of the adsorbent, the multistage condensation method is used for liquefying and separating NMP in tail gas through the change of pressure and temperature, but the limit on the emission concentration of NMP is continuously increased due to the increasingly strict environmental protection requirement, the condensation method cannot achieve the required effect, the spraying method is generally used for spraying and absorbing tail gas by water to obtain the required emission concentration, but the water consumption is high, and the purification and refining cost is high due to the difficulty in obtaining high-concentration NMP recovery liquid (generally only 50% ~ 80%).
In addition, since the NMP recovery liquid contains a certain amount of impurities such as non-volatile substances generated in hot air drying and a part of metal ions dissolved on the equipment pipeline in addition to water, it is imperative to purify the NMP recovery liquid.
Disclosure of Invention
Based on this, it is necessary to provide an apparatus and a method for recovering and purifying N-methylpyrrolidone, which can obtain a high concentration NMP product and meet the exhaust emission index, and also have a higher yield and a lower cost.
A device for recovering and purifying N-methyl pyrrolidone comprises a recovery part and a purification part, wherein the recovery part comprises an absorption tower, a feeding fan communicated with the lower part of the absorption tower and at least three stages of circulating cooling devices arranged outside the absorption tower from top to bottom in sequence, each stage of circulating cooling device comprises a circulating pump and a cooler, and the circulating pump, the cooler and the absorption tower of each stage of circulating cooling device are connected in sequence to form a circulating cooling loop;
the purification part comprises a rectifying tower, a tower top condenser, a reflux tank, a reflux pump, a tower top vacuum pump, a reboiler, a demister, a product liquid separating tank, a product condenser, a product buffer tank, a product pump and a product vacuum pump, wherein one end of the tower top condenser is communicated with the top of the rectifying tower, the other end of the tower top condenser is communicated with the upper part of the rectifying tower sequentially through the reflux tank and the reflux pump, the tower top vacuum pump is communicated with the reflux tank and used for controlling the vacuum degree in the rectifying tower, one end of the product liquid separating tank extends into a tower kettle of the rectifying tower through the demister, the other end of the product liquid separating tank is communicated with the product pump sequentially through the product condenser and the product buffer tank, and the product vacuum pump is communicated with the product buffer tank and used for controlling the vacuum degree in the product buffer;
the middle part of the rectifying tower is communicated with the bottom of the absorption tower through a circulating pump of the last stage of circulating cooling device.
In one embodiment, the device for recovering and purifying the N-methylpyrrolidone further comprises a feeding heat exchanger, the middle part of the rectifying tower is communicated with the bottom of the absorption tower sequentially through the feeding heat exchanger and a circulating pump of the last stage of circulating cooling device, and the product liquid separation tank is communicated with the product condenser through the feeding heat exchanger.
In one embodiment, the apparatus for recovering and purifying N-methylpyrrolidone further comprises an absorption liquid recycling line, one end of which is communicated with the reflux pump, and the other end of which is communicated with the upper part or the middle upper part of the absorption tower.
In one embodiment, the device for recovering and purifying N-methylpyrrolidone further comprises a waste liquid pump, and the waste liquid pump is communicated with the bottom of the rectifying tower and is used for discharging the waste liquid after pressurization.
In one embodiment, the reboiler is an internal kettle reboiler, an external thermosiphon reboiler, or a falling film reboiler.
In one embodiment, the absorption column is a packed column or a plate column, and the rectification column is a packed column or a plate column.
A method for recovering and purifying N-methyl pyrrolidone comprises the following steps:
pressurizing tail gas containing N-methyl pyrrolidone by a feeding fan, then feeding the tail gas into the lower part of an absorption tower, reversely contacting with a purifying liquid from the upper part of the absorption tower, and performing at least three-stage circulating cooling absorption to obtain the tail gas which reaches the standard and an absorbing liquid containing N-methyl pyrrolidone;
and (2) feeding the absorption liquid containing the N-methyl pyrrolidone into the middle part of a rectifying tower for rectification, gathering light components to the top of the tower through a rectifying section, condensing the light components through a condenser at the top of the tower, then feeding the light components into a reflux tank, boosting the light components by a reflux pump, then feeding the light components into the rectifying tower, gathering the heavy components to the bottom of the tower through a stripping section, removing large liquid drops through a demister, removing small liquid drops through a product liquid separation tank, condensing the product condenser, then feeding the heavy components into a product buffer tank, boosting the product by a product pump, and then extracting to obtain the N-methyl pyrrolidone product.
In one embodiment, the purified liquid comprises purified water and/or recycled absorption liquid, and the recycled recovery liquid is from the reflux pump.
In one embodiment, the method for recovering and purifying N-methylpyrrolidone further comprises the following steps:
and (3) exchanging heat between the absorption liquid containing the N-methyl pyrrolidone and a gas-phase product from the product liquid separation tank, and then sending the absorption liquid containing the N-methyl pyrrolidone and the gas-phase product into the middle part of the rectifying tower.
In one example, the rectification column has an overhead pressure of 5 kPa ~ 20kPa, an overhead temperature of 40 ℃ ~ 100 ℃, a reflux to feed ratio of 2 ~ 6, and a theoretical plate number of 4 ~ 15.
According to the device and the method for recovering and purifying the N-methyl pyrrolidone, at least three stages of circulating cooling devices are arranged to obtain the absorption liquid containing the high-concentration N-methyl pyrrolidone and reach the tail gas emission standard, and the cooler of each stage of circulating cooling device can also control the absorption temperature and increase the absorption effect. The product is directly extracted from the tower kettle to obtain a high-purity N-methyl pyrrolidone product, and the waste water at the tower top is directly and repeatedly absorbed and utilized to increase the yield of the N-methyl pyrrolidone and avoid the treatment cost.
Drawings
Fig. 1 is a schematic structural view of an apparatus for recovering and purifying N-methylpyrrolidone according to an embodiment.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Referring to fig. 1, an apparatus for recovering and purifying N-methylpyrrolidone includes a recovery portion and a purification portion.
Wherein, the recovery part comprises an absorption tower 10, a feeding fan 20 communicated with the lower part of the absorption tower 10 and at least three stages of circulating cooling devices 30 which are arranged outside the absorption tower 10 from top to bottom in sequence.
Each stage of hydronic cooling apparatus 30 includes a circulation pump 32 and a cooler 34. The circulating pump 32, the cooler 34 and the absorption tower 10 of each stage of the circulating cooling device 30 are connected in sequence to form a circulating cooling loop.
It is understood that the portion of the circulating pump of each stage of the circulating cooling device, which communicates with the absorption tower, is lower than the portion of the cooler of the stage of the circulating cooling device, which communicates with the absorption tower.
The recovery part is used for pressurizing tail gas containing the N-methyl pyrrolidone by a feeding fan 20, then sending the tail gas into the lower part of the absorption tower 10, reversely contacting with the purified liquid from the upper part of the absorption tower 10, and obtaining the tail gas which reaches the standard and the absorption liquid containing the N-methyl pyrrolidone by the circulating cooling absorption of at least three stages of circulating cooling devices 30.
In the embodiment, the top of the absorption tower 10 is directly connected with the atmosphere through a pipeline, so that the emission of the tail gas reaching the standard is realized.
Because the tail gas containing the N-methyl pyrrolidone has higher temperature, and the absorption effect of the purifying liquid is gradually reduced along with the increase of the temperature, the absorption temperature is controlled by arranging at least three stages of circulating cooling devices 30, so that the concentration of the N-methyl pyrrolidone in the absorbing liquid reaches more than 85%.
Wherein, the purification part comprises a rectifying tower 40, an overhead condenser 50, a reflux tank 60, a reflux pump 70, an overhead vacuum pump 80, a reboiler 90, a demister 100, a product liquid separating tank 110, a product condenser 120, a product buffer tank 130, a product pump 140 and a product vacuum pump 150.
The rectifying column 40 is a packed column or a plate column.
One end of the tower top condenser 50 is communicated with the top of the rectifying tower 40, and the other end is communicated with the upper part of the rectifying tower 40 through a reflux tank 60 and a reflux pump 70 in sequence.
The top vacuum pump 80 is communicated with the reflux drum 60 and is used for controlling the vacuum degree in the rectifying tower 40.
One end of the product liquid separation tank 110 extends into the tower kettle of the rectifying tower 40 through the demister 100, and the other end is communicated with the product pump 140 through the product condenser 120 and the product buffer tank 130 in sequence, and is used for pressurizing and extracting the N-methyl pyrrolidone product.
A product vacuum pump 150 is in communication with the product surge tank 130 for controlling the vacuum level within the product surge tank 130.
In order to reduce energy consumption, the middle part of the rectifying tower 40 is communicated with the bottom of the absorption tower 10 through the circulation pump 32 of the last stage circulation cooling device 30.
The purification part is used for pressurizing absorption liquid containing N-methyl pyrrolidone by a circulating pump 32 of a last stage circulating cooling device 30 and then sending the absorption liquid into the middle part of a rectifying tower 40 for rectification, light components are gathered to the top of the tower through a rectification section, the light components at the top of the tower are condensed by a tower top condenser 50 and then enter a reflux tank 60, liquid phase in the reflux tank 60 mainly comprises water and a small amount of N-methyl pyrrolidone, and the liquid phase in the reflux tank 60 is pressurized by a reflux pump 70 and then returns to the rectifying tower 40.
In order to increase the yield of the product and to eliminate the cost of wastewater treatment, in this embodiment, the above apparatus for recovering and purifying N-methylpyrrolidone further comprises an absorption liquid recycling line 200. The absorption liquid reuse line 200 has one end communicating with the reflux pump 70 and the other end communicating with the upper or middle upper part of the absorption tower 10. Namely, the liquid phase in the reflux tank 60 is pressurized by the reflux pump 70 and then divided into two paths, one path is used as reflux and returned to the rectifying tower 40, and the other path is used as absorption liquid and returned to the upper part or the middle upper part of the absorption tower 10 for repeated use through the absorption liquid reuse pipeline 200.
The heavy components are gathered to the bottom of the tower through the stripping section, large liquid drops are removed through a demister 100, small liquid drops are removed through a product liquid separating tank 110, the product is condensed through a product condenser 120, and then the product is fed into a product buffer tank 130, and liquid phase in the product buffer tank 130 is pressurized through a product pump 140 and then is directly extracted as a product.
Since the liquid phase of the N-methylpyrrolidone in the bottom of the rectifying column 40 may generate non-volatile matter and dissolve metal ion impurities, the direct extraction from the bottom can be used to avoid the problem and obtain a high-purity N-methylpyrrolidone product.
Wherein, reboiler 90 is built-in cauldron formula reboiler to increase the tower cauldron space and increase the efficiency of taking off the liquid of taking out the product.
It is understood that in other embodiments, an external thermosiphon reboiler or a falling film reboiler may be used as the reboiler.
In order to further reduce energy consumption, the above apparatus for recovering and purifying N-methylpyrrolidone further comprises a feed heat exchanger 160.
Specifically, the middle part of the rectifying tower 40 is communicated with the bottom of the absorption tower 10 sequentially through the feed heat exchanger 160 and the circulating pump 32 of the last stage of the circulating cooling device 30, and the product separation tank 110 is communicated with the product condenser 120 through the feed heat exchanger 160.
The feed heat exchanger 160 is used for feeding the absorption liquid containing the N-methyl pyrrolidone and the gas-phase product from the product liquid separation tank 110 into the rectifying tower 40 for rectification after heat exchange.
In this embodiment, the apparatus for recovering and purifying N-methylpyrrolidone further includes a waste liquid pump 170, and the waste liquid pump 170 is connected to the bottom of the rectifying tower 40, and discharges the waste liquid after pressurizing the waste liquid.
The device for recovering and purifying the N-methyl pyrrolidone adopts a stable, reliable and continuous recovery part and a purification part to meet the requirement of long-period operation of production; arranging at least three stages of circulating cooling devices to obtain absorption liquid containing more than 85% of N-methyl pyrrolidone and reach the tail gas emission standard; the product at the tower bottom of the rectifying tower is directly extracted to obtain a high-purity N-methyl pyrrolidone product; the wastewater at the top of the rectifying tower is directly and repeatedly absorbed and utilized to increase the yield of the N-methyl pyrrolidone and avoid the treatment cost.
The method for recovering and purifying the N-methyl pyrrolidone by using the device comprises the following steps:
s110, pressurizing tail gas containing N-methyl pyrrolidone by a feeding fan, then feeding the tail gas into the lower part of an absorption tower, reversely contacting the tail gas with a purifying liquid from the upper part of the absorption tower, and performing at least three-stage circulating cooling absorption to obtain the tail gas which reaches the standard and is discharged and the absorbing liquid containing the N-methyl pyrrolidone.
Wherein, the purifying liquid is purified water and/or circulating absorption liquid. The circulating absorption liquid comes from a reflux pump.
Specifically, tail gas containing N-methyl pyrrolidone is pressurized by a feeding fan and then sent to the lower part of an absorption tower, purifying liquid is sent to the upper part of the absorption tower, the tail gas containing N-methyl pyrrolidone continuously rises and is circularly absorbed by the purifying liquid to obtain tail gas without N-methyl pyrrolidone (namely tail gas discharged by reaching the standard), the purifying liquid continuously flows to the lower part and is circularly absorbed to continuously increase the concentration of N-methyl pyrrolidone, so that the absorption liquid containing N-methyl pyrrolidone with the concentration of more than 85% is obtained.
Because the tail gas containing the N-methyl pyrrolidone has higher temperature, the absorption effect of the purifying liquid is gradually reduced along with the increase of the temperature, and therefore, the absorption temperature is controlled by at least three stages of circulating cooling absorption, so that the concentration of the N-methyl pyrrolidone in the absorbing liquid reaches more than 85 percent.
S120, feeding the absorption liquid containing the N-methyl pyrrolidone into the middle of a rectifying tower for rectification, gathering light components to the top of the tower through a rectifying section, condensing the light components through a condenser at the top of the tower, then feeding the light components into a reflux tank, boosting the light components by a reflux pump, then feeding the light components into the rectifying tower, gathering the heavy components to the bottom of the tower through a stripping section, removing large liquid drops through a demister, removing small liquid drops through a product liquid separation tank, condensing the product condenser, then feeding the product into a product buffer tank, boosting the product by a product pump, and then extracting the product to obtain the N-methyl pyrrolidone product.
Wherein the top pressure of the rectifying tower is 5 kPa ~ 20kPa, the top temperature is 40 ℃ ~ 100 ℃, the reflux-feed ratio is 2 ~ 6, and the theoretical plate number is 4 ~ 15.
In order to further reduce energy consumption, the absorption liquid containing the N-methyl pyrrolidone and a gas-phase product from a product liquid separation tank are subjected to heat exchange and then sent to the middle part of a rectifying tower for rectification.
Specifically, the absorption liquid containing the N-methyl pyrrolidone is pressurized by a circulating pump of a last stage of circulating cooling device, and is subjected to heat exchange with a gas-phase product from a product liquid separating tank through a feeding heat exchanger, then the gas-phase product is fed into a rectifying tower, light components are gathered to the top of the tower through a rectifying section, the light components at the top of the tower are condensed by a tower top condenser and then are fed into a reflux tank, the liquid phase in the reflux tank is mainly water and also contains a small amount of N-methyl pyrrolidone, the liquid phase in the reflux tank is pressurized by the reflux pump and then is divided into two paths, one path is used as reflux and returns to the rectifying tower, and the other path is used as absorption. The heavy components are gathered to the bottom of the tower through a stripping section, large liquid drops are removed through a demister, small liquid drops are removed through a product liquid separating tank, heat exchange is carried out through a feeding heat exchanger, a product condenser is condensed, and then the product buffer tank is filled with the heavy components, and liquid phase in the product buffer tank is pressurized through a product pump and then directly extracted as a product.
The method for recovering and purifying the N-methyl pyrrolidone uses a stable, reliable and continuous recovery and purification process to meet the requirement of long-period operation of production; obtaining absorption liquid containing more than 85% of N-methyl pyrrolidone by at least three stages of circulating cooling and reaching the tail gas emission standard; the product at the tower bottom of the rectifying tower is directly extracted to obtain a high-purity N-methyl pyrrolidone product; the wastewater at the top of the rectifying tower is directly and repeatedly absorbed and utilized to increase the yield of the N-methyl pyrrolidone and avoid the treatment cost.
The following are specific examples.
Example 1
Tail gas (8000 Nm) containing N-methyl pyrrolidone3And/h, NMP400 kg/h) is pressurized by a feeding fan and then is fed into the lower part of the absorption tower, purified liquid (2500 kg/h of purified water, 50kg/h of circulating absorption liquid and NMP5 kg/h) is fed into the upper part of the absorption tower, tail gas containing N-methyl pyrrolidone which continuously rises is in reverse contact with the purified liquid which continuously flows to the lower part, and the tail gas which reaches the standard and is discharged (the concentration of NMP is less than 10 ppm) and the absorption liquid containing 90% of N-methyl pyrrolidone are obtained through three-stage circulating cooling absorption.
And (3) exchanging heat between the absorption liquid containing the N-methyl pyrrolidone with the concentration of 90% and a gas-phase product through a feeding heat exchanger to 120 ℃, and then rectifying the absorption liquid in a rectifying tower, wherein the rectifying tower adopts a packed tower, the pressure at the top of the tower is 10kPa, the temperature at the top of the tower is 50 ℃, the reflux-feeding ratio is 3, and the number of theoretical plates is 6. Light components are gathered to the top of the tower through a rectifying section, the light components at the top of the tower are condensed by a condenser at the top of the tower and then enter a reflux tank, liquid phase in the reflux tank is mainly water and also contains a small amount of NMP (about 10%), the liquid phase in the reflux tank is pressurized by a reflux pump and then divided into two paths, one path is used as reflux and returned to the rectifying tower (1500 kg/h), and the other path (50 kg/h) is used as absorption liquid and returned to the upper part of the absorption tower. The heavy components are gathered to the bottom of the tower through a stripping section, large liquid drops are removed through a demister, small liquid drops are removed through a product liquid separating tank, heat exchange is carried out through a feeding heat exchanger, a product condenser is condensed and then enters a product buffer tank, liquid phase in the product buffer tank is directly extracted as a product after being pressurized through a product pump, and an NMP product (400 kg/h) with the purity of 99.9% is obtained.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (7)
1. The method for recovering and purifying the N-methyl pyrrolidone comprises a recovery part and a purification part, and is characterized in that the recovery part comprises an absorption tower, a feeding fan communicated with the lower part of the absorption tower and at least three stages of circulating cooling devices arranged outside the absorption tower from top to bottom in sequence, each stage of circulating cooling device comprises a circulating pump and a cooler, and the circulating pump, the cooler and the absorption tower of each stage of circulating cooling device are connected in sequence to form a circulating cooling loop;
the purification part comprises a rectifying tower, a tower top condenser, a reflux tank, a reflux pump, a tower top vacuum pump, a reboiler, a demister, a product liquid separating tank, a product condenser, a product buffer tank, a product pump and a product vacuum pump, wherein one end of the tower top condenser is communicated with the top of the rectifying tower, the other end of the tower top condenser is communicated with the upper part of the rectifying tower sequentially through the reflux tank and the reflux pump, the tower top vacuum pump is communicated with the reflux tank and used for controlling the vacuum degree in the rectifying tower, one end of the product liquid separating tank extends into a tower kettle of the rectifying tower through the demister, the other end of the product liquid separating tank is communicated with the product pump sequentially through the product condenser and the product buffer tank, and the product vacuum pump is communicated with the product buffer tank and used for controlling the vacuum degree in the product buffer;
pressurizing tail gas containing N-methyl pyrrolidone by a feeding fan, then feeding the tail gas into the lower part of an absorption tower, reversely contacting with a purifying liquid from the upper part of the absorption tower, and performing at least three-stage circulating cooling absorption to obtain the tail gas which reaches the standard and an absorbing liquid containing N-methyl pyrrolidone;
feeding the absorption liquid containing the N-methyl pyrrolidone into the middle part of a rectifying tower for rectification, gathering light components to the top of the tower through a rectifying section, condensing the light components through a condenser at the top of the tower, then feeding the light components into a reflux tank, boosting the light components by a reflux pump, then feeding the light components into the rectifying tower, gathering the heavy components to the bottom of the tower through a stripping section, removing large liquid drops through a demister, removing small liquid drops through a product liquid separation tank, condensing the product liquid drops through a product condenser, feeding the product liquid drops into a product buffer tank, boosting the product liquid through a product pump, and then extracting to obtain an N-methyl pyrrolidone;
the middle part of the rectifying tower is communicated with the bottom of the absorption tower through a circulating pump of the last stage of circulating cooling device;
the device for recovering and purifying the N-methyl pyrrolidone further comprises a feeding heat exchanger, the middle part of the rectifying tower is communicated with the bottom of the absorption tower through the feeding heat exchanger and a circulating pump of the last stage of circulating cooling device in sequence, and the product liquid separation tank is communicated with the product condenser through the feeding heat exchanger;
the device for recovering and purifying the N-methylpyrrolidone further comprises an absorption liquid recycling pipeline, wherein one end of the absorption liquid recycling pipeline is communicated with the reflux pump of the rectifying tower, and the other end of the absorption liquid recycling pipeline is communicated with the upper part or the middle upper part of the absorption tower.
2. The method for recovering and purifying N-methylpyrrolidone according to claim 1, wherein the apparatus for recovering and purifying N-methylpyrrolidone further comprises a waste liquid pump, and the waste liquid pump is communicated with the bottom of the rectification column and is used for discharging the waste liquid after pressurization.
3. The method of claim 1, wherein the reboiler is an internal kettle reboiler, an external thermosiphon reboiler, or a falling film reboiler.
4. The method for recovering and purifying N-methylpyrrolidone according to claim 1, wherein the absorption column is a packed column or a plate column, and the rectification column is a packed column or a plate column.
5. The method of claim 1, wherein the purge comprises a purge water and/or a recycle absorbent from the reflux pump.
6. The method for recovering and purifying N-methylpyrrolidone according to claim 1, wherein the method for recovering and purifying N-methylpyrrolidone further comprises the following steps:
the absorption liquid containing the N-methyl pyrrolidone and a gas-phase product from a product liquid separation tank are sent into a rectifying tower after heat exchange
And a middle part.
7. The method for recovering and purifying N-methylpyrrolidone according to claim 1, wherein the overhead pressure of the rectifying tower is 5 kPa to 20kPa, the overhead temperature is 40 ℃ to 100 ℃, the reflux-feed ratio is 2 to 6, and the number of theoretical plates is 4 to 15.
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| CN111170919B (en) * | 2019-12-26 | 2021-04-09 | 重庆市中润化学有限公司 | NMP waste liquid recovery process |
| CN111167146A (en) * | 2019-12-26 | 2020-05-19 | 重庆市中润化学有限公司 | NMP waste liquid is retrieved with dehydration tower |
| CN112094217A (en) * | 2020-09-15 | 2020-12-18 | 安徽晟捷新能源科技有限公司 | Efficient and environment-friendly recovery device and method for N-methylpyrrolidone |
| CN115716792B (en) * | 2022-05-17 | 2023-11-07 | 重庆中润新材料股份有限公司 | NMP heavy component recycling method |
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