N-methyl pyrrolidone recovery device
By utilizing the overhead gas from the NMP product tower as a heating source, the steam consumption of the dehydration and distillation towers is reduced, and the overhead condenser is eliminated, thus solving the problem of high energy consumption in the N-methylpyrrolidone recovery process and achieving energy saving and consumption reduction.
Patent Information
- Application Number
- CN202423165865.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-22
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2034-12-22
AI Technical Summary
The current N-methylpyrrolidone recovery process has high energy consumption, mainly due to the large amount of steam used in the bottom of the column and the large amount of cooling water used in the top of the column.
The overhead gas from the NMP product column is used as the heat source for heating the dehydration and distillation columns. By utilizing the heat from the overhead gas of the product column, the amount of steam used in the bottom of the dehydration and distillation columns is reduced, and the condensed gas liquid is directly returned to the top reflux tank, eliminating the need for a top condenser.
It significantly reduced the amount of steam used in the bottom of the dehydration tower and distillation tower, thus lowering energy consumption and achieving economic and energy-saving effects.
Smart Images
Figure CN223760435U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to an N-methylpyrrolidone (NMP) recovery device. Background Technology
[0002] N-Methylpyrrolidone (NMP) is a nitrogen-containing heterocyclic compound, a colorless to pale yellow transparent polar oily liquid with a slight ammonia odor. It is characterized by a high boiling point, low viscosity, good stability, non-corrosiveness, low toxicity, and strong dissolving power. With the national promotion of clean energy utilization and green, low-carbon development, NMP is widely used in industries such as petrochemicals, pharmaceuticals, pesticides, coatings, and lithium-ion batteries. In recent years, with the widespread adoption and promotion of mobile phones and new energy vehicles, the lithium battery industry has experienced rapid development, and the use of NMP, as an important auxiliary coating material for the positive electrode of lithium batteries, has increased significantly. Because NMP is relatively expensive and harmful to human health, its recycling is of great significance for reducing pollution, protecting the environment, and lowering the production cost of lithium batteries.
[0003] The main process for recovering NMP from waste organic solvents via distillation is three-tower distillation. The main flow of the three-tower distillation process is as follows: In the first distillation column, most of the water in the NMP-containing waste organic solvent is removed; the remaining water in the concentrated solution is removed in the second distillation column; and the NMP semi-finished product after two stages of dehydration is refined in the third distillation column to obtain high-purity NMP. Because conventional NMP recovery processes use steam heating in all three distillation columns, and the overhead gas is condensed using circulating cooling water, the equipment consumes a lot of energy and has high production costs. Summary of the Invention
[0004] The technical problem to be solved by this utility model is to provide an N-methylpyrrolidone recovery device, which can reduce the amount of steam in the bottom of the column and cooling water in the top of the column during the N-methylpyrrolidone recovery process, and reduce the energy consumption required in the recovery process.
[0005] This utility model provides an N-methylpyrrolidone recovery device, including a dehydration tower, a distillation tower, a product tower, a dehydration tower reboiler disposed at the bottom of the dehydration tower, a distillation tower reboiler disposed at the bottom of the distillation tower, and a product tower top reflux tank disposed at the top of the product tower; the liquid phase outlet of the bottom of the dehydration tower is connected to the feed inlet of the distillation tower, and the liquid phase outlet of the bottom of the distillation tower is connected to the feed inlet of the product tower; the characteristic of this device is that it further includes a dehydration tower. The reboiler and the distillation column reboiler are located at the bottom of the dehydration column and the distillation column reboiler, respectively. The hot-side inlet of the dehydration column reboiler and the hot-side inlet of the distillation column reboiler are connected to the vapor phase outlet at the top of the product column. The hot-side outlet of the dehydration column reboiler and the hot-side outlet of the distillation column reboiler are connected to the inlet of the reflux tank at the top of the product column. The liquid phase outlet of the reflux tank at the top of the product column is divided into two paths: one path is connected to the reflux port at the top of the product column, and the other path is used for discharging the product.
[0006] This utility model has at least the following advantages and features:
[0007] 1. In this embodiment of the utility model, the top gas outlet of the product column is connected to the hot side inlet of the reboiler of the dehydration column and the hot side inlet of the reboiler of the distillation column, respectively. The dehydration column and the distillation column in the top gas feeding device of the NMP product column are used as heating heat sources, which can significantly reduce the amount of bottom steam used in the dehydration column and the distillation column. At the same time, the condensed product column top gas condensate is directly returned to the product column top reflux tank, which can eliminate the need for the top condenser of the product column, reduce the amount of cooling water used at the top of the column, and achieve the effect of economic and energy saving.
[0008] 2. In this embodiment of the invention, the overhead gas of the product column is used as a heat source for heating the bottom liquid of both the dehydration column and the distillation column. The condensate from the overhead gas of the product column output from the reboiler of the dehydration column and the reboiler of the distillation column is directly returned to the reflux tank at the top of the product column. This maximizes the utilization of the heat from the overhead gas of the product column and avoids the situation where the heat from the overhead gas of the product column is not fully utilized and needs to be condensed, making it more energy-efficient and effective. Attached Figure Description
[0009] Figure 1 A schematic diagram of an N-methylpyrrolidone recovery device according to an embodiment of the present invention is shown. Detailed Implementation
[0010] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0011] Please refer to Figure 1An N-methylpyrrolidone recovery device according to an embodiment of the present invention includes a dehydration tower T1, a distillation tower T2, a product tower T3, a dehydration tower reboiler 11, a dehydration tower reboiler 12, a distillation tower reboiler 13, a distillation tower reboiler 14, a product tower reboiler 15, a dehydration tower top condenser 21, a dehydration tower top reflux tank 22, a distillation tower top condenser 23, a distillation tower top reflux tank 24, and a product tower top reflux tank 26.
[0012] The liquid outlet of the bottom of the dehydration tower T1 is connected to the feed inlet located in the middle of the distillation tower T2, and the liquid outlet of the bottom of the distillation tower T2 is connected to the feed inlet located in the middle of the product tower T3.
[0013] The dehydration tower reboiler 11 and the dehydration tower reboiler 12 are respectively installed in the bottom of the dehydration tower. The cold side inlet and cold side outlet of the dehydration tower reboiler 11 are respectively connected to the first sampling outlet and the first reflux port installed in the bottom of the dehydration tower. The cold side inlet and cold side outlet of the dehydration tower reboiler 12 are respectively connected to the second sampling outlet and the second reflux port installed in the bottom of the dehydration tower.
[0014] The distillation column reboiler 13 and the distillation column reboiler 14 are respectively installed in the distillation column bottom. The cold side inlet and cold side outlet of the distillation column reboiler 13 are respectively connected to the third sampling outlet and the third reflux port installed in the distillation column bottom. The cold side inlet and cold side outlet of the distillation column reboiler 14 are respectively connected to the fourth sampling outlet and the fourth reflux port installed in the distillation column bottom.
[0015] The product column reboiler 15 is located in the bottom of the product column. The cold side inlet and cold side outlet of the product column reboiler 15 are connected to the fifth sampling outlet and the fifth reflux outlet located in the bottom of the product column, respectively. The dehydration column reboiler 11, the distillation column reboiler 13, and the product column reboiler 15 all use external heating steam as a heat source.
[0016] The hot-side inlet of the dehydration tower reboiler 12 and the hot-side inlet of the distillation tower reboiler 14 are respectively connected to the vapor phase outlet at the top of the product tower T3. The hot-side outlet of the dehydration tower reboiler 12 and the hot-side outlet of the distillation tower reboiler 14 are respectively connected to the inlet of the product tower top reflux tank 26 located at the top of the product tower. The liquid phase outlet of the product tower top reflux tank 26 is divided into two paths: one path is connected to the top reflux port of the product tower T3, and the other path is used for NMP product discharge.
[0017] The dehydration tower top condenser 21 and the dehydration tower top reflux tank 22 are respectively installed at the top of the dehydration tower. The gas phase outlet at the top of the dehydration tower T1 is connected to the hot side inlet of the dehydration tower top condenser 21, and the hot side outlet of the dehydration tower top condenser 21 is connected to the inlet of the dehydration tower top reflux tank 22. The liquid phase outlet of the dehydration tower top reflux tank 22 is divided into two paths: one path is connected to the top reflux port of the dehydration tower T1, and the other path is used to discharge wastewater.
[0018] The distillation column top condenser 23 and the distillation column top reflux tank 24 are respectively located at the top of the distillation column. The vapor phase outlet at the top of distillation column T2 is connected to the hot-side inlet of the distillation column top condenser 23, and the hot-side outlet of the distillation column top condenser 23 is connected to the inlet of the distillation column top reflux tank 24. The liquid phase outlet of the distillation column top reflux tank 24 is divided into two paths: one path is connected to the top reflux port of distillation column T2, and the other path is used to discharge wastewater. Both the dehydration column top condenser 21 and the distillation column top condenser 23 use external cooling water as their cold source.
[0019] The working process of an N-methylpyrrolidone recovery device according to an embodiment of the present invention is described below.
[0020] Waste liquid S1 containing NMP enters dehydration tower T1. The operating pressure of dehydration tower T1 is 0-30 kPaA, the top temperature is 40-80℃, and the bottom temperature is 100-180℃. The overhead gas from dehydration tower T1 is condensed by the top condenser 21 and then enters the top reflux tank 22. Part of the condensate from the overhead gas is refluxed, and part is discharged as wastewater S5. Of the two reboilers in dehydration tower T1, the heat source for reboiler 12 is the overhead gas from product tower T3, while the steam reboiler 11 is heated by steam.
[0021] The bottom product from dehydration column T1 enters distillation column T2. Distillation column T2 operates at a pressure of 0-30 kPaA, with a top temperature of 40-80℃ and a bottom temperature of 100-180℃. The overhead gas from the distillation column is condensed in the overhead condenser 23 and then enters the overhead reflux tank 24. Part of the condensate is refluxed, and part is discharged as wastewater S10. Of the two reboilers in distillation column T2, the heat source for reboiler 14 is the overhead gas from product column T3, while the steam reboiler 13 is heated by steam.
[0022] The bottom product of distillation column T2 enters product column T3. Product column T3 operates at a pressure of 0-30 kPaA, with a top temperature of 80-170℃ and a bottom temperature of 100-180℃. The top gas from the product column is heated in the reboiler 12 of the dehydration column and the reboiler 14 of the distillation column. After heating, the top gas condenses and enters the top reflux tank 26 of the product column. Part of the condensate from the top gas is collected as NMP recovery product S15, and part is returned to the top of the column as reflux. The bottom liquid is discharged as recovery residue S17 through the waste liquid outlet located at the bottom of the product column.
[0023] The waste organic solvent containing NMP loses most of its water in the dehydration tower T1. The concentrated liquid after dehydration loses the remaining water in the distillation tower. The NMP semi-finished product after two stages of dehydration is refined in the product tower to obtain a high-purity NMP product.
[0024] This embodiment of the invention uses the dehydration tower and distillation tower in the overhead gas feeding device of the NMP product tower as the heating heat source. The insufficient heat is supplemented by heating steam, which can significantly reduce the amount of steam used in the bottom of the dehydration tower and distillation tower. At the same time, the condensed product tower overhead gas condensate is directly returned to the product tower overhead reflux tank, which can eliminate the need for the product tower overhead condenser, reduce the amount of cooling water used at the top of the tower, and achieve the effect of economic and energy saving.
Claims
1. An N-methylpyrrolidone recovery apparatus comprising a dehydration column, a rectification column, a product column, a dehydration column steam reboiler provided in a column bottom of the dehydration column, a rectification column steam reboiler provided in a column bottom of the rectification column, and a product column overhead reflux drum provided in an overhead of the product column; a column bottom liquid phase outlet of the dehydration column is communicated with a feed inlet of the rectification column, a column bottom liquid phase outlet of the rectification column is communicated with a feed inlet of the product column; characterized in that, The N-methylpyrrolidone recovery device further comprises a dehydration column reboiler and a rectification column reboiler, the dehydration column reboiler is arranged at the column bottom of the dehydration column, and the rectification column reboiler is arranged at the column bottom of the rectification column. The hot side inlet of the dehydration column reboiler and the hot side inlet of the rectification column reboiler are respectively communicated with the overhead gas phase outlet of the product column, the hot side outlet of the dehydration column reboiler and the hot side outlet of the rectification column reboiler are respectively communicated with the inlet of the overhead reflux tank of the product column, and the liquid phase outlet of the overhead reflux tank of the product column is divided into two paths: one path is communicated with the overhead reflux inlet of the product column, and the other path is used for discharging.
2. The N-methylpyrrolidone recovery apparatus of claim 1, wherein, The N-methylpyrrolidone recovery device comprises a dehydration column overhead condenser and a dehydration column overhead reflux tank, the overhead gas phase outlet of the dehydration column is communicated with the hot side inlet of the dehydration column overhead condenser, the hot side outlet of the dehydration column overhead condenser is communicated with the inlet of the dehydration column overhead reflux tank, and the liquid phase outlet of the dehydration column overhead reflux tank is divided into two paths: one path is communicated with the overhead reflux inlet of the dehydration column, and the other path is used for discharging waste water.
3. The N-methylpyrrolidone recovery apparatus of claim 1, wherein, The N-methylpyrrolidone recovery device comprises a rectification column overhead condenser and a rectification column overhead reflux tank, the overhead gas phase outlet of the rectification column is communicated with the hot side inlet of the rectification column overhead condenser, the hot side outlet of the rectification column overhead condenser is communicated with the inlet of the rectification column overhead reflux tank, and the liquid phase outlet of the rectification column overhead reflux tank is divided into two paths: one path is communicated with the overhead reflux inlet of the rectification column, and the other path is used for discharging waste water.
4. The N-methylpyrrolidone recovery apparatus of claim 1, wherein, The N-methylpyrrolidone recovery device comprises a product column steam reboiler, and the product column steam reboiler is arranged at the column bottom of the product column.
5. The N-methylpyrrolidone recovery apparatus of claim 1, wherein, The column bottom of the product column is provided with a waste liquid outlet.