CN216756389U

CN216756389U - System for use maleic anhydride as raw materials preparation NMP

Info

Publication number: CN216756389U
Application number: CN202220196931.3U
Authority: CN
Inventors: 王春生; 王微; 司涛; 李竞周; 荆荣鹤; 李彬秾
Original assignee: Tianjin Haicheng Chemical Technology Co ltd
Current assignee: Tianjin Haicheng Chemical Technology Co ltd
Priority date: 2022-01-24
Filing date: 2022-01-24
Publication date: 2022-06-17
Anticipated expiration: 2032-01-24

Abstract

The utility model provides a system for preparing NMP (N-methyl pyrrolidone) by taking maleic anhydride as a raw material, which comprises a hydrogenation reactor, a hydrogenation separation device, an amination reactor and an amination separation device, wherein the hydrogenation reactor is used for carrying out hydrogenation reaction on the maleic anhydride to obtain a hydrogenation reaction mixture, the hydrogenation separation device is used for separating the hydrogenation reaction mixture to obtain gamma-butyrolactone, the amination reactor is used for carrying out amination reaction on the gamma-butyrolactone to obtain an amination reaction mixture, and the amination separation device is used for separating the amination reaction mixture to obtain the NMP. The system for preparing NMP by taking maleic anhydride as the raw material realizes the continuous production process of GBL through one-step hydrogenation of maleic anhydride and the continuous production process of GBL through one-step hydrogenation of maleic anhydride, refining GBL and amination of the refined GBL and a methylamine aqueous solution to synthesize NMP.

Description

System for use maleic anhydride as raw materials preparation NMP

Technical Field

The utility model belongs to the field of chemical synthesis, and particularly relates to a system for preparing NMP (N-methyl pyrrolidone) by using maleic anhydride as a raw material.

Background

With the explosion of new energy automobile industry in China and the updating frequency and speed of mobile phones and notebook computers, the lithium ion battery industry has a steady growth trend, the industry has developed into the industry with the highest industrialization degree in China in the emerging industry of China, N-methylpyrrolidone (NMP) is used as an indispensable material for lithium ion battery production, accounts for about 3-6% of the production cost of the lithium ion battery, and the market demand is continuously expanded.

The method for synthesizing NMP by methylating gamma-butyrolactone (GBL) is the most applied and mature process route at present, and a 40% methylamine water process is mostly adopted in industrial production.

In the GBL synthesis process, the 1, 4-Butanediol (BDO) gas phase dehydrogenation method has better economic benefit due to the advantages of mature technology, simple flow, good product quality, safety, energy conservation and the like, and about 75 percent of enterprises in the field adopt the method to dominate.

Because BDO is used for producing polyester engineering plastics such as PBAT and the like, polyurethane, Tetrahydrofuran (THF) and the like in large quantity at present, BDO is short in supply and demand and the price is continuously increased dramatically especially for the rapid development of degradable plastics industries such as PBAT and the like. The BDO capacity is mainly based on a calcium carbide route acetylene aldehyde method, in the past, the calcium carbide supply in China is sufficient, the calcium carbide method is a production mode with lower cost, and with the coming of the relevant policies of 'carbon peak reaching', 'carbon neutralization' in China, the calcium carbide is used as the industry with high energy consumption and high carbon emission, the admission threshold is further improved, the newly increased capacity is extremely difficult, and part of the low-efficiency stock capacity is expected to be eliminated gradually. The price of the calcium carbide breaks through the new and high price of the calcium carbide in recent ten years, the cost of producing BDO by a calcium carbide method is greatly increased, and the cost of synthesizing GBL from BDO is greatly increased.

Along with the breakthrough of the process for preparing maleic anhydride by oxidizing n-butane and industrial large-scale production, the production cost of maleic anhydride is greatly reduced, and the technology has more and more competitiveness and good development and application prospects. However, the hydrogenation of maleic anhydride via intermediate GBL produces BDO, so the production process for preparing GBL by using BDO for reverse dehydrogenation is slightly unreasonable.

The GBL process route prepared by maleic anhydride hydrogenation is a new synthesis route with the greatest development prospect at present, and has wide research and industrialization realization due to the advantages of raw material sources, technical economy, product composition, process flow and the like. Since the hydrogenation of maleic anhydride is a complex reaction, a series of byproducts are generated in addition to the main product, and the process of product separation is particularly critical for obtaining a high-purity target product.

At present, few reports are provided for a production process for preparing GBL by direct hydrogenation of maleic anhydride and a continuous production process for preparing GBL by hydrogenation of maleic anhydride and synthesizing NMP by re-methylation of GBL into methylamine, the industrialized GBL has complex production and separation process and high energy consumption, maleic anhydride is difficult to completely convert in the hydrogenation reaction process, the boiling point of the maleic anhydride is only 2 ℃ different from that of the GBL, and incomplete reaction brings difficulty to subsequent separation operation and influences the purity of the GBL. Therefore, the development of a continuous process production technology which has the advantages of simple process, complete reaction, energy saving, consumption reduction, cost saving and environmental protection is urgently needed.

SUMMERY OF THE UTILITY MODEL

In view of the above, the utility model aims to provide a system for preparing NMP from maleic anhydride as a raw material, which has the advantages of simple flow, complete reaction, good product quality, high yield, environmental friendliness, energy conservation, continuity and stability, so as to effectively solve the problems of long process route, incomplete reaction, high production cost, high energy consumption, high investment, high difficulty in treating three wastes and the like in the existing industry, and improve the comprehensive economic benefits of GBL and NMP production.

In order to achieve the purpose, the technical scheme of the utility model is realized as follows:

a system for preparing NMP by taking maleic anhydride as a raw material comprises a hydrogenation reactor, a hydrogenation separation device, an amination reactor and an amination separation device, wherein the hydrogenation reactor is used for enabling maleic anhydride to be subjected to hydrogenation reaction to obtain a hydrogenation reaction mixture containing gamma-butyrolactone and hydrogenation byproducts, the hydrogenation separation device is used for separating the hydrogenation reaction mixture and removing the hydrogenation byproducts to obtain high-purity gamma-butyrolactone, the amination reactor is used for enabling the gamma-butyrolactone and a methylamine water solution to be subjected to amination reaction to obtain an amination reaction mixture containing NMP and the amination byproducts, and the amination separation device is used for separating the amination reaction mixture and removing the amination byproducts to obtain high-purity NMP.

Further, the hydrogenation separation device comprises a gas-liquid separation tank, a crude separation tower, a THF tower and a GBL separation tower system,

the feed inlet of the gas-liquid separation tank is communicated with the discharge outlet of the hydrogenation reactor, the liquid phase discharge outlet is communicated with the feed inlet at the side of the rough separation tower, the gas phase discharge outlet is communicated with the feed inlet of the hydrogenation reactor,

the top discharge hole of the rough separation tower is communicated with the feed inlet of a THF tower, the bottom discharge hole is communicated with the side feed inlet of a GBL separation tower system, the top discharge hole of the THF tower is communicated with the feed inlet at the upper end of the rough separation tower,

and a discharge port in the middle of the GBL separation tower system is communicated with a feed port at the bottom of the amination reactor.

Further, a catalyst bed layer is arranged in the coarse component tower, a lower end feeding hole for a third reactant to enter is formed in the side wall of the coarse component tower below the catalyst bed layer, and the third reactant comprises methanol, ethanol, propanol and any substance or substances which can react with maleic anhydride and convert into easily separated heavy components without affecting the quality of the gamma-butyrolactone product.

Furthermore, the hydrogenation separation device also comprises an oil-water separation device and a drying and recycling device,

the middle discharge port of the rough separation tower is communicated with the top feed port of the oil-water separation device, the middle azeotrope discharge port of the oil-water separation device is communicated with the middle feed port of the rough separation tower, and the organic phase discharge port is communicated with the middle feed port of the drying recovery device.

Furthermore, the hydro-separation device also comprises a heat exchanger, the heat exchanger comprises a heat source pipeline and a cold source pipeline, two ends of the heat source pipeline are respectively communicated with a discharge port at the top of the THF tower and a feed inlet at the upper end of the rough separation tower, and two ends of the cold source pipeline are respectively communicated with a cold material discharge port and a cold material return port at the lower part of the oil-water separation device.

Further, the amination separation device comprises a methylamine removing tower, an NMP dehydrating tower and an NMP rectifying tower,

the feed inlet of the de-methylamine tower is communicated with the discharge outlet at the top of the amination reactor, the discharge outlet at the top is communicated with the feed inlet at the bottom of the amination reactor, the discharge outlet at the bottom is communicated with the feed inlet at the middle part of the NMP dehydration tower,

and a discharge hole at the bottom of the NMP dehydration tower is communicated with a feed inlet at the middle part of the NMP rectifying tower.

Further, a discharge hole at the top of the de-methanamine tower is communicated with a tail gas treatment device.

Further, a discharge hole in the top of the NMP dehydration tower is communicated with a wastewater treatment device.

Furthermore, a discharge hole at the top of the NMP rectifying tower is communicated with an NMP refining device, and a discharge hole at the bottom of the NMP rectifying tower is communicated with a tar recovery device.

The working principle of the system for preparing NMP by taking maleic anhydride as a raw material is as follows:

raw materials of maleic anhydride, hydrogen and a solvent pass through a hydrogenation reactor under certain operation conditions, GBL and hydrogenation by-products of Tetrahydrofuran (THF), water, GBL light components, intermediate components, heavy components and the like are generated under the action of a catalyst, reaction products enter a gas-liquid separation tank, noncondensable gas such as hydrogen and the like is separated from the top of the tank and circulated to the inlet of the hydrogenation reactor, and a liquid-phase product at the bottom of the tank enters a rough separation tower from the upper part of a catalyst bed layer of the rough separation tower for separation;

the third reactant enters the rough separation tower from the lower part of a catalyst bed layer of the rough separation tower under certain conditions, and further reacts with unconverted maleic anhydride in the hydrogenation process to generate easily separated heavy components, wherein the maleic anhydride is completely converted, and the easily separated heavy components are extracted from the bottom of the rough separation tower;

THF, water azeotrope and the like are arranged at the top of the rough separation tower and enter a THF tower, the azeotrope at the top of the THF tower returns to the rough separation tower, and a THF product is extracted from the bottom of the THF tower;

extracting an oil-water azeotrope from the middle part of the rough separation tower, feeding the oil-water azeotrope into an oil-water separation device, separating waste water containing trace organic matters, returning a secondary oil-water azeotrope generated by the oil-water separation device to the rough separation tower, feeding high-concentration organic matters containing trace water generated by the oil-water separation device into a drying and recovering device, and recovering the organic matters in the high-concentration organic matters after one or more dehydration modes such as molecular sieve adsorption, inorganic membrane dehydration, rectification separation and the like are carried out;

the bottom of the coarse separation tower is a mixture of GBL, GBL light components, intermediate components, heavy components and the like, the mixture is extracted and sent to a GBL separation tower system, the GBL separation tower system comprises a plurality of separation towers, high-purity GBL products and solvents are obtained through separation, the high-purity GBL products can be used as target products, and also can be used as intermediate products for producing NMP products, and the solvents are returned to the hydrogenation reactor for recycling.

High-purity GBL and methylamine water solution enter an amination reactor under certain operation conditions, NMP and amination by-products, such as water, tar heavy matters and the like, are synthesized without catalysis, an amination product enters a de-methylamine tower, a certain concentration methylamine water solution is extracted from the top of the de-methylamine tower and returns to an inlet of the amination reactor for cyclic utilization, a small amount of non-condensable gas is extracted from the top of the de-methylamine tower and enters a tail gas treatment device, and the non-condensable gas is discharged after reaching the standard after treatment;

NMP, water, tar heavy matters and the like are arranged at the bottom of the de-methylamine tower, and are extracted and sent to an NMP dehydration tower; wastewater extracted from the top of the NMP dehydrating tower enters a wastewater treatment device, is discharged or utilized after reaching the standard after being treated, and is extracted and sent to an NMP rectifying tower, wherein NMP, tar heavy matters and the like exist at the bottom of the NMP dehydrating tower; the bottom of the NMP rectifying tower is provided with heavy tar and the like, and the heavy tar and the like enter a tar recovery device to be treated so as to recover a small amount of NMP, tar and the like; NMP is arranged at the top of the NMP rectifying tower, and selectively enters an NMP refining device according to the index requirements of downstream NMP products to produce reagent-grade, electronic-grade, industrial-grade or common-grade NMP products.

Further, a differential pressure rectification method is adopted in the THF refining process, a rough separation tower is used as a low-pressure tower, a THF tower is used as a high-pressure tower, a high-concentration THF and water azeotrope is arranged at the top of the rough separation tower, a low-concentration THF and water azeotrope is arranged at the top of the THF tower, the azeotrope is circularly rectified between the rough separation tower and the THF tower, and a THF product is finally extracted from the bottom of the THF tower.

Furthermore, the oil-water azeotrope is circularly separated between the rough separation tower and the oil-water separation device, and finally water for removing organic matters is extracted from the oil-water separation device, so that the maximum separation of water in reaction products is realized, the maximum removal of the organic matters in the wastewater is realized, and the separated wastewater can be directly discharged without treatment.

Furthermore, the THF tower is operated under high pressure, the temperature of the top of the THF tower is 5-25 ℃ or above higher than the temperature of cold materials of the oil-water separation device, the latent heat of the gas phase at the top of the THF tower is utilized to heat the cold materials of the oil-water separation device, part of steam is replaced, the consumption of cooling media such as circulating water for condensing the gas phase at the top of the THF tower is saved, thermal coupling is carried out through a heat exchanger, the recycling of heat is realized, and the energy consumption is saved.

Furthermore, the solvent separated by the GBL separation tower system is recycled, and the high-concentration organic matters containing trace water generated by the oil-water separation device enter a drying and recycling device, so that the organic matters can be further recycled, the material utilization rate is improved, and the wastewater discharge is reduced.

Further, the top of the amine removing tower contains the non-condensable gas of methylamine, the top of the NMP dehydrating tower is used for treating the top wastewater of the NMP rectifying tower, the bottom of the NMP rectifying tower is used for treating heavy tar substances, and the top NMP of the NMP rectifying tower is respectively treated by a tail gas treatment device, a wastewater treatment device, a tar recovery device and an NMP refining device, so that the three wastes are discharged up to the standard, the NMP and tar recovery is realized, the production of high-index NMP products is realized, the environment is protected, the resources are saved, and the product scheme is flexible.

Compared with the prior art, the system for preparing NMP by using maleic anhydride as a raw material has the following advantages:

(1) the system for preparing NMP by taking maleic anhydride as the raw material realizes the continuous production process of GBL through one-step hydrogenation of maleic anhydride and the continuous production process of synthesizing NMP through amination of GBL refined by one-step hydrogenation of maleic anhydride and methylamine water solution;

(2) the system for preparing NMP by taking maleic anhydride as the raw material realizes the pre-removal of maleic anhydride which is not completely converted in the hydrogenation reaction process, thereby solving the problem that the separation of the GBL of maleic anhydride and the GBL of maleic anhydride with the boiling point difference of only 2 ℃ is difficult in the subsequent product separation process, and improving the purity of the GBL product;

(3) the system for preparing NMP by using maleic anhydride as the raw material realizes effective separation of hydrogenation byproduct organic matters and water azeotrope, has simple separation process and low energy consumption, realizes maximum separation of water in hydrogenation reaction products and maximum removal of organic matters in wastewater, and can directly discharge the separated wastewater without treatment;

(4) the system for preparing NMP by using maleic anhydride as the raw material realizes the circulation of the solvent, realizes the maximum recovery of organic matters, improves the utilization rate of materials and reduces the discharge of waste water;

(5) the tetrahydrofuran refining process in the system for preparing NMP by taking maleic anhydride as the raw material adopts a differential pressure rectification method, a rough separation tower is used as a low-pressure tower, and a THF tower is used as a high-pressure tower, so that a set of low-pressure tower system is saved. The gas phase latent heat at the top of the THF tower is fully and reasonably utilized to be thermally coupled with the cold materials of the oil-water separation device, so that the heat is recycled, the energy consumption is saved, and the production cost is reduced;

(6) according to the system for preparing NMP by using maleic anhydride as the raw material, three wastes are directionally treated in the amination product separation part, so that organic matters are recovered to the maximum extent, the wastes are discharged after reaching standards, and the system is green and environment-friendly;

(7) the system for preparing NMP by using maleic anhydride as the raw material has the advantages of short flow, low energy consumption, continuity and stability, good GBL purity of the intermediate product, high yield, capability of producing various specifications such as reagent grade, electronic grade, industrial grade, common grade and the like according to the specification of the NMP product, and flexible and adjustable product scheme.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the utility model and, together with the description, serve to explain the utility model and not to limit the utility model. In the drawings:

FIG. 1 is a schematic diagram of the connection structure of a system for preparing NMP from maleic anhydride according to an embodiment of the present invention.

Description of reference numerals:

1. a hydrogenation reactor; 2. a gas-liquid separation tank; 3. roughly dividing the tower; 4. a THF column; 5. an oil-water separation device; 6. a drying and recovering device; 7. a GBL separation column system; 8. an amination reactor; 9. a de-methanamine tower; 10. an NMP dehydration tower; 11. an NMP rectification column; 12. a tail gas treatment device; 13. a wastewater treatment device; 14. an NMP refining device; 15. a tar recovery device; 101. a first pipeline; 102. a second pipeline; 103. a third pipeline; 104. a fourth pipeline; 105. a fifth pipeline; 106. a sixth pipeline; 107. a seventh pipeline; 108. an eighth pipeline; 109. a ninth conduit; 110. a tenth pipeline; 111. an eleventh line; 112. a twelfth pipeline; 113. a thirteenth pipeline; 114. a fourteenth pipeline; 115. a fifteenth pipeline; 116. a sixteenth pipeline; 117. a seventeenth pipeline; 118. an eighteenth pipeline; 119. a nineteenth pipeline; 120. a twentieth pipeline; 121. a twenty-first pipeline; 122. a twenty-second conduit; 123. a twenty-third line; 124. a twenty-fourth pipeline; 125. a twenty-fifth pipeline; 126. a twenty-sixth pipeline; 127. a twenty-seventh pipeline; 128. a twenty-eighth pipeline; 129. a twenty-ninth pipeline; 130. thirtieth pipeline.

Detailed Description

Unless defined otherwise, technical terms used in the following examples have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods are conventional methods unless otherwise specified.

The present invention will be described in detail with reference to the following examples and accompanying drawings.

As shown in fig. 1, the present embodiment provides a system for preparing NMP using maleic anhydride as a raw material, which includes a hydrogenation reactor 1, a gas-liquid separation tank 2, a rough separation tower 3, a THF tower 4, an oil-water separation device 5, a drying recovery device 6, a GBL separation tower system 7, an amination reactor 8, a de-amination tower 9, an NMP dehydration tower 10, an NMP rectification tower 11, a tail gas treatment device 12, a wastewater treatment device 13, an NMP refining device 14, and a tar recovery device 15.

Maleic anhydride and a solvent respectively enter a hydrogenation reactor 1 through a first pipeline 101 and a second pipeline 102, make-up hydrogen enters the hydrogenation reactor 1 through a fifth pipeline 105, the bottom of the hydrogenation reactor 1 is connected with an inlet of a gas-liquid separation tank 2 through a third pipeline 103, hydrogenation products enter the hydrogenation reactor from the first pipeline, the top of the gas-liquid separation tank 2 is connected with the inlet of the hydrogenation reactor 1 through a fourth pipeline 104, separated hydrogen and non-condensable gas return to the hydrogenation reactor 1 from the second pipeline, the bottom of the gas-liquid separation tank 2 is connected with a crude separation tower 3 through a sixth pipeline 106, liquid phase products enter the crude separation tower 3 from a position above a catalyst bed through the sixth pipeline 106, a third reactant (such as methanol) enters the crude separation tower 3 from a position below the catalyst bed through a seventh pipeline 107 connected with the side of the crude separation tower 3, and the third reactant further reacts with the maleic anhydride which is not converted by the hydrogenation reaction to generate an easily separated heavy component. The high-concentration THF water azeotrope obtained from the top of the rough separation tower 3 enters a THF tower 4 through an eighth pipeline 108, the THF tower 4 is communicated with the upper part of the rough separation tower 3 through a ninth pipeline 109, the low-concentration THF water azeotrope at the top of the THF tower 4 returns to the rough separation tower 3 through the ninth pipeline 109, and the kettle of the THF tower 4 is communicated with a tenth pipeline 110, so that a THF product is extracted.

An oil-water azeotrope produced at the tower side of the rough separation tower 3 enters the oil-water separation device 5 through an eleventh pipeline 111, a secondary oil-water azeotrope produced by the oil-water separation device 5 returns to the rough separation tower 3 through a twelfth pipeline 112, the oil-water separation device 5 produces waste water for removing organic matters through a thirteenth pipeline 113, high-concentration organic matters containing trace water produced by the oil-water separation device 5 enter the drying and recovery device 6 through a fourteenth pipeline 114, and are treated through one or more dehydration modes such as molecular sieve adsorption, inorganic membrane dehydration, rectification separation and the like, the organic matters in the waste water are recovered, and the organic matters are extracted through a fifteenth pipeline 115.

GBL, GBL light components, intermediate components, heavy components and the like are arranged in the tower bottom of the rough separation tower 3 and enter a GBL separation tower system 7 through a sixteenth pipeline 116, the GBL separation tower system 7 is connected with a seventeenth pipeline 117, an eighteenth pipeline 118, a nineteenth pipeline 119, a twentieth pipeline 120 and a twenty first pipeline 121, the GBL light components, the solvent, the intermediate components, the refined GBL and the heavy components are sequentially extracted, the GBL separation tower system can be further connected with more pipelines, and the extraction sequence can be adjusted and optimized according to the hydrogenation reaction condition. Refined GBL may be withdrawn via twentieth line 120 and may also be introduced into amination reactor 8 via twentieth line 120.

The methylamine aqueous solution enters the amination reactor 8 through a twenty-second pipeline 122, the outlet of the amination reactor 8 is connected with the tower side of the de-methylamine tower 9 through a twenty-third pipeline 123, the amination reaction product enters from the outlet, the tower top of the de-methylamine tower 9 is connected with the inlet of the amination reactor 8 through a twenty-fourth pipeline 124, the tower top of the de-methylamine tower 9 is connected with the tail gas treatment device 12 through a twenty-fifth pipeline 125, the methylamine aqueous solution at the tower top of the de-methylamine tower 9 returns to the amination reactor 8 through the twenty-fourth pipeline 124, the non-condensable gas at the tower top of the de-methylamine tower 9 enters the tail gas treatment device 12 through the twenty-fifth pipeline 125, and the tail gas is discharged after reaching the standard after treatment;

NMP, water, tar heavy substances and the like are filled in the tower bottom of the methylamine removing tower 9 and enter the NMP dehydrating tower 10 through a twenty-sixth pipeline 126, the tower top of the NMP dehydrating tower 10 is connected with the wastewater treatment device 13 through a twenty-seventh pipeline 127, and wastewater at the tower top enters from the tower top and is recycled after reaching the standard;

NMP, tar heavy matter and the like are arranged at the tower bottom of the NMP dehydrating tower 10 and enter the NMP rectifying tower 11 through a twenty-eighth pipeline 128, the tar heavy matter and the like are arranged at the tower bottom of the NMP rectifying tower 11 and are extracted through a thirtieth pipeline 130 and enter the tar recovery device 15, a small amount of NMP and tar heavy matter can be recovered after treatment, a twenty-ninth pipeline 129 is connected to the tower top of the NMP rectifying tower 11, NMP is extracted from the NMP and enters the NMP refining device 14, and NMP products such as reagent grade, electronic grade, industrial grade or common grade and the like are produced according to the index requirements of downstream products.

In the embodiment, the latent heat of the high-temperature position at the top of the high-pressure THF tower 4 is transferred to the cold material of the low-pressure oil-water separation device 5 through the heat exchanger, the gas phase at the top of the high-pressure tower is condensed while the cold material of the low-pressure system is heated, and finally the condensed heat is circulated back to the high-pressure tower system, so that the latent heat of the gas phase at the top of the high-pressure tower is fully utilized for thermal coupling, the heat is recycled, the consumption of steam and cooling media is saved, the energy consumption is reduced, and the heat exchanger is used as a condenser and a heater, so that one heat exchanger is saved. In other embodiments, the tetrahydrofuran differential pressure rectification process uses the rough separation tower 3 as a low-pressure tower, and the THF differential pressure rectification can be realized only by using one high-pressure THF tower 4, so that a set of tower system is saved. Therefore, in actual production, the investment of the device and the operation cost can be reduced to different degrees.

In this embodiment, the third reactant is selectively added according to the maleic anhydride conversion degree of the hydrogenation reaction, and the catalyst bed is selectively disposed in the rough separation tower 3, so as to ensure complete conversion of maleic anhydride, and thus the separation purity of the GBL product is not affected.

In this embodiment, the oil-water separation device 5 and the drying recovery device 6 may be operated intermittently or continuously depending on the hydrogenation conditions, the wastewater treatment measures, and the like.

Taking a 5 ten thousand tons/year N-methyl pyrrolidone (8000 hours per year of operation) device as an example, NMP which is a main product produced by the system in the embodiment can meet the requirement of electronic grade, the purity of GBL which is an intermediate product is more than or equal to 99.7 wt%, THF which is a byproduct is more than or equal to 99.95 wt%, the yield is more than or equal to 98.0%, and the concentration of organic matters in the waste water treated by the separation part of the hydrogenation product is less than or equal to 500 ppm.

The latent heat of the gas phase at the top of the THF tower 4 is fully utilized, steam can be saved by 0.8-2.8 tons/hour, circulating water can be saved by 50-180 tons/hour, and annual carbon emission reduction is 450-1500 tons.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the utility model, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A system for preparing NMP by taking maleic anhydride as a raw material is characterized in that: the hydrogenation reactor is used for carrying out hydrogenation reaction on maleic anhydride to obtain a hydrogenation reaction mixture, the hydrogenation separation device is used for separating the hydrogenation reaction mixture to obtain gamma-butyrolactone, the amination reactor is used for carrying out amination reaction on the gamma-butyrolactone to obtain an amination reaction mixture, and the amination separation device is used for separating the amination reaction mixture to obtain NMP.

2. The system of claim 1, wherein: the hydrogenation separation device comprises a gas-liquid separation tank, a rough separation tower, a THF tower and a GBL separation tower system,

3. The system of claim 2, wherein: and a catalyst bed layer is arranged in the rough separation tower, and a lower end feeding hole for a third reactant to enter is formed in the side wall of the rough separation tower below the catalyst bed layer.

4. The system of claim 2, wherein: the hydrogenation separation device also comprises an oil-water separation device and a drying recovery device,

5. The system of claim 4, wherein: the hydro-separation device further comprises a heat exchanger, the heat exchanger comprises a heat source pipeline and a cold source pipeline, two ends of the heat source pipeline are respectively communicated with a discharge port at the top of the THF tower and a feed inlet at the upper end of the rough separation tower, and two ends of the cold source pipeline are respectively communicated with a discharge port of a cold material at the lower part of the oil-water separation device and a return port of the cold material.

6. The system of claim 1, wherein: the amination separation device comprises a methylamine removing tower, an NMP dehydrating tower and an NMP rectifying tower,

7. The system of claim 6, wherein: and a discharge hole at the top of the de-methylamine tower is communicated with a tail gas treatment device.

8. The system of claim 6, wherein: and a discharge hole at the top of the NMP dehydration tower is communicated with a wastewater treatment device.

9. The system of claim 6, wherein: the NMP rectifying tower is characterized in that a discharge port at the top of the NMP rectifying tower is communicated with an NMP refining device, and a discharge port at the bottom of the NMP rectifying tower is communicated with a tar recovery device.