Thermal coupling energy-saving tower of NMP four-tower rectification system
By using a four-tower thermal coupling design and efficient structured packing, the problem of ineffective utilization of waste heat in the NMP four-tower distillation system was solved, realizing energy cascade utilization and efficient heat distribution, and improving the energy utilization efficiency and mass transfer effect of the NMP distillation process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- MAIQI CHEM CO LTD
- Filing Date
- 2025-05-28
- Publication Date
- 2026-05-12
AI Technical Summary
In the existing NMP four-tower distillation system, the waste heat of the high-temperature tower is not effectively recovered and utilized. The condenser and reboiler use traditional shell-and-tube heat exchangers, which have low heat transfer efficiency. The internal components of the tower mostly use random packing or ordinary trays, resulting in large pressure drop and unsatisfactory mass transfer effect.
It adopts a four-tower thermal coupling design, uses high-efficiency structured packing made of ceramic material, optimizes heat transfer with plate heat exchangers, sets up an energy-saving device to recover waste heat, and achieves energy cascade utilization and efficient heat distribution through a heat medium circulation system.
It significantly improves the energy utilization efficiency of the NMP distillation process, reduces energy consumption, and improves mass transfer efficiency and heat transfer efficiency, while maintaining a stable and compact overall structure.
Smart Images
Figure CN224220764U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of four-tower distillation technology, and in particular to a thermally coupled energy-saving tower for an NMP four-tower distillation system. Background Technology
[0002] N-Methylpyrrolidone (NMP), as an important polar aprotic solvent, is widely used in lithium batteries, electronic chemicals, pharmaceuticals, and coatings due to its excellent solubility and chemical stability. Distillation purification is a key process step in the production of NMP.
[0003] Currently, multi-tower continuous distillation is mainly used in industry for the separation and purification of NMP. However, due to the high boiling point and poor thermal stability of NMP, traditional distillation processes face technical challenges such as high energy consumption and low separation efficiency.
[0004] Existing NMP four-tower distillation systems generally suffer from low thermal energy utilization, mainly due to the independent operation of each distillation tower, the failure to effectively recover and utilize the waste heat of the high-temperature tower, the use of traditional shell-and-tube heat exchangers in the condenser and reboiler resulting in low heat transfer efficiency, and the use of random packing or ordinary trays for the tower internals, leading to large pressure drop and unsatisfactory mass transfer. To address these issues, we have introduced a heat-coupled energy-saving tower for NMP four-tower distillation systems. Utility Model Content
[0005] This utility model discloses a heat-coupled energy-saving tower for an NMP four-tower distillation system, aiming to solve the technical problems of ineffective recovery and utilization of waste heat in high-temperature towers, the use of traditional shell-and-tube heat exchangers in condensers and reboilers with low heat transfer efficiency, and the use of random packing or ordinary trays for tower internals, resulting in large pressure drop and unsatisfactory mass transfer effect.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A thermally coupled energy-saving column for an NMP four-column distillation system includes a first distillation column, a second distillation column, a third distillation column, and a fourth distillation column connected in series. The first distillation column has a first condenser at its top, and its bottom is thermally coupled to the middle of the second distillation column via a first reboiler. The second distillation column has a second condenser at its top, and its bottom is thermally coupled to the middle of the third distillation column via a second reboiler. The third distillation column has a third condenser at its top, and its bottom is thermally coupled to the middle of the fourth distillation column via a third reboiler. The fourth distillation column has a fourth condenser at its top, and its bottom is connected to a product outlet.
[0008] The four-tower thermal coupling design enables cascaded energy utilization, ceramic packing improves separation efficiency, plate heat exchangers optimize heat transfer, and waste heat recovery system reduces energy consumption. The overall structure is compact and stable, significantly improving the energy utilization efficiency of the NMP distillation process.
[0009] In a preferred embodiment, the first, second, third, and fourth distillation columns are all equipped with highly efficient structured packing, which is made of ceramic material with a specific geometric structure.
[0010] Highly efficient structured packings made of ceramic materials have a larger specific surface area and better corrosion resistance, which can significantly improve gas-liquid mass transfer efficiency and reduce pressure drop in the column. At the same time, the high temperature resistance of ceramic materials is particularly suitable for the high-boiling-point distillation process of NMP.
[0011] In a preferred embodiment, plate heat exchangers are provided on the outer sides of the first reboiler, the second reboiler, and the third reboiler, and the plate heat exchangers are composed of multiple parallel heat exchange plates.
[0012] The structure of multiple parallel heat exchange plates significantly increases the heat exchange area, improves heat transfer efficiency, and makes heat transfer between towers more thorough and uniform.
[0013] In a preferred embodiment, the bottom of the fourth distillation column is equipped with an energy-saving device that recovers waste heat from the distillation process.
[0014] The energy-saving device installed at the bottom of the fourth distillation column can effectively recover the waste heat in the distillation process and use it to preheat the raw material liquid, further reducing the system's energy consumption requirements and maximizing energy utilization.
[0015] In a preferred embodiment, the outer walls of the first, second, third, and fourth distillation columns are all covered with an insulation layer, which is made of a high-temperature resistant heat-insulating material.
[0016] The insulation layer covering the outer wall of each column is made of high-temperature resistant heat insulation material, which effectively reduces heat loss during the distillation process, maintains the stability of the temperature inside the column, and improves the thermal energy utilization efficiency of the entire system.
[0017] In a preferred embodiment, a heat medium circulation system is fixedly connected to the top of the first distillation column, and the first condenser, second condenser, third condenser and fourth condenser are all connected to the heat medium circulation system.
[0018] The heat medium circulation system connecting each condenser enables the recycling of the heat medium and allows for precise control of the temperature and flow rate of the heat medium according to process requirements, ensuring efficient distribution and stable transfer of heat energy.
[0019] The thermally coupled energy-saving tower of the NMP four-tower distillation system provided by this utility model has the following advantages:
[0020] Firstly, the four-tower thermal coupling design enables cascaded energy utilization, ceramic packing improves separation efficiency, plate heat exchangers optimize heat transfer, and waste heat recovery systems reduce energy consumption. The overall structure is compact and stable, significantly improving the energy utilization efficiency of the NMP distillation process.
[0021] Secondly, the energy-saving device installed at the bottom of the fourth distillation column can effectively recover waste heat from the distillation process and use it to preheat the feed liquid, further reducing the system's energy consumption and maximizing energy utilization. The insulation layer covering the outer wall of each column is made of high-temperature resistant insulation material, which effectively reduces heat loss during the distillation process, maintains the stability of the temperature inside the column, and improves the overall system's thermal efficiency. The heat medium circulation system connecting each condenser realizes the recycling of the heat medium and can precisely control the temperature and flow rate of the heat medium according to process requirements, ensuring efficient distribution and stable transfer of heat energy. Attached Figure Description
[0022] Figure 1 This is a three-dimensional schematic diagram of a thermally coupled energy-saving tower for an NMP four-tower distillation system proposed in this utility model.
[0023] Figure 2 This is a three-dimensional bottom view of the thermally coupled energy-saving tower of an NMP four-tower distillation system proposed in this utility model.
[0024] Figure 3 This is a front view schematic diagram of the thermally coupled energy-saving tower of an NMP four-tower distillation system proposed in this utility model.
[0025] Figure 4 This is a top view sectional view of the heat-coupled energy-saving tower of an NMP four-tower distillation system proposed in this utility model.
[0026] Figure 5 This invention proposes a thermally coupled energy-saving tower for an NMP four-tower distillation system. Figure 2 A magnified diagram of point A.
[0027] In the attached diagram: 1. First distillation column; 2. First condenser; 3. Second distillation column; 4. Second condenser; 5. Third distillation column; 6. Third condenser; 7. Fourth distillation column; 8. Fourth condenser; 9. First reboiler; 10. Second reboiler; 11. Third reboiler; 12. Energy saver; 13. Product outlet; 14. High-efficiency structured packing; 15. Insulation layer; 16. Heat medium circulation system; 17. Plate heat exchanger. Detailed Implementation
[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and marked in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0029] The thermally coupled energy-saving tower of the NMP four-tower distillation system disclosed in this utility model is mainly used in four-tower distillation scenarios.
[0030] Reference Figures 1-5 A thermally coupled energy-saving column of an NMP four-column distillation system includes a first distillation column 1, a second distillation column 3, a third distillation column 5, and a fourth distillation column 7 connected in series. The first distillation column 1 has a first condenser 2 at its top, and its bottom is thermally coupled to the middle of the second distillation column 3 via a first reboiler 9. The second distillation column 3 has a second condenser 4 at its top, and its bottom is thermally coupled to the middle of the third distillation column 5 via a second reboiler 10. The third distillation column 5 has a third condenser 6 at its top, and its bottom is thermally coupled to the middle of the fourth distillation column 7 via a third reboiler 11. The fourth distillation column 7 has a fourth condenser 8 at its top, and its bottom is connected to a product outlet 13. Each of the first distillation column 1, second distillation column 3, third distillation column 5, and fourth distillation column 7 is equipped with high-efficiency structured packing 14, which is made of ceramic material with a specific geometric structure. Plate heat exchangers 17 are provided on the outer side of the first reboiler 9, the second reboiler 10 and the third reboiler 11. The plate heat exchangers 17 are composed of multiple parallel heat exchange plates.
[0031] In this embodiment: the raw material first enters the first distillation column 1 for preliminary separation. The vapor at the top of the column is partially refluxed after being condensed by the first condenser 2, and the remainder enters the next distillation column. The liquid at the bottom of the first distillation column 1 provides a heat source for the second distillation column 3 through the first reboiler 9, and so on to achieve cascade utilization of heat. The heat medium circulation system 16 recovers and redistributes the heat from each condenser. The energy saver 12 recovers the waste heat from the fourth distillation column 7 for preheating the feed. The high-efficiency structured packing 14 improves the mass transfer efficiency. The four-column thermal coupling design achieves cascade utilization of energy. The ceramic packing improves the separation efficiency. The plate heat exchanger 17 optimizes heat transfer. The waste heat recovery system reduces energy consumption. The overall structure is compact and stable, significantly improving the energy utilization efficiency of the NMP distillation process.
[0032] In the above technical solution, considering that the waste heat of the high-temperature tower cannot be effectively recovered and utilized, the condenser and reboiler use traditional shell-and-tube heat exchangers with low heat transfer efficiency, and the tower internals mostly use random packing or ordinary trays, resulting in large pressure drop and unsatisfactory mass transfer effect. In order to solve these problems, the specific operation is as follows:
[0033] Reference Figures 1-5 In a preferred embodiment, an energy-saving device 12 is installed at the bottom of the fourth distillation column 7, which recovers waste heat from the distillation process. The outer walls of the first distillation column 1, the second distillation column 3, the third distillation column 5, and the fourth distillation column 7 are all covered with an insulation layer 15, which is made of high-temperature resistant heat-insulating material. A heat transfer medium circulation system 16 is fixedly connected to the top of the first distillation column 1, and the first condenser 2, the second condenser 4, the third condenser 6, and the fourth condenser 8 are all connected to the heat transfer medium circulation system 16.
[0034] In this embodiment, the energy-saving device 12 installed at the bottom of the fourth distillation column 7 can effectively recover the waste heat during the distillation process and use it to preheat the raw material liquid, further reducing the system's energy consumption requirements and maximizing energy utilization. The insulation layer 15 covering the outer wall of each column is made of high-temperature resistant insulation material, which effectively reduces heat loss during the distillation process, maintains the stability of the temperature inside the column, and improves the overall system's thermal energy utilization efficiency. The heat medium circulation system 16 connecting each condenser realizes the recycling of the heat medium and can precisely control the temperature and flow rate of the heat medium according to process requirements, ensuring efficient distribution and stable transfer of heat energy.
[0035] Working Principle: During operation, the raw material first enters the first distillation column 1 for preliminary separation. The vapor at the top of the column is partially refluxed after condensation by the first condenser 2, while the remainder enters the next distillation column. The liquid at the bottom of the first distillation column 1 provides a heat source for the second distillation column 3 through the first reboiler 9, and so on, achieving cascaded heat utilization. The heat transfer medium circulation system 16 recovers and redistributes the heat from each condenser, and the energy-saving device 12 recovers the waste heat from the fourth distillation column 7 for preheating the feed. The high-efficiency structured packing 14 improves mass transfer efficiency, the plate heat exchanger 17 optimizes heat transfer, and the insulation layer 15 reduces heat loss. The entire system achieves efficient energy utilization and efficient NMP separation. The final product is discharged from the product outlet 13 at the bottom of the fourth distillation column 7.
[0036] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. The substitutions may be replacements of some structures, devices, or method steps, or they may be complete technical solutions. Equivalent substitutions or modifications made based on the technical solution and inventive concept of this utility model should all be covered within the protection scope of this utility model.
Claims
1. A thermally coupled energy-saving column for an NMP four-column distillation system, comprising a first distillation column (1), a second distillation column (3), a third distillation column (5), and a fourth distillation column (7) connected in series, characterized in that: The first distillation column (1) is provided with a first condenser (2) at the top, and its bottom is thermally coupled to the middle of the second distillation column (3) through a first reboiler (9). The second distillation column (3) is provided with a second condenser (4) at the top, and its bottom is thermally coupled to the middle of the third distillation column (5) through a second reboiler (10). The third distillation column (5) is provided with a third condenser (6) at the top, and its bottom is thermally coupled to the middle of the fourth distillation column (7) through a third reboiler (11). The fourth distillation column (7) is provided with a fourth condenser (8) at the top, and its bottom is connected to a product outlet (13).
2. The heat-coupled energy-saving tower of the NMP four-tower distillation system according to claim 1, characterized in that: The first distillation column (1), the second distillation column (3), the third distillation column (5) and the fourth distillation column (7) are all equipped with highly efficient structured packing (14).
3. The heat-coupled energy-saving tower of the NMP four-tower distillation system according to claim 1, characterized in that: The first reboiler (9), the second reboiler (10) and the third reboiler (11) are all provided with plate heat exchangers (17) on their outer sides. The plate heat exchangers (17) are composed of multiple parallel heat exchange plates.
4. The heat-coupled energy-saving tower of the NMP four-tower distillation system according to claim 1, characterized in that: The fourth distillation column (7) is equipped with an energy-saving device (12) at the bottom, which recovers the waste heat in the distillation process.
5. The thermally coupled energy-saving tower of the NMP four-tower distillation system according to claim 1, characterized in that: The outer walls of the first distillation column (1), the second distillation column (3), the third distillation column (5) and the fourth distillation column (7) are all covered with a heat insulation layer (15), which is made of high temperature resistant heat insulation material.
6. The thermally coupled energy-saving tower of the NMP four-tower distillation system according to claim 1, characterized in that: The top of the first distillation column (1) is fixedly connected to a heat medium circulation system (16), and the first condenser (2), the second condenser (4), the third condenser (6) and the fourth condenser (8) are all connected to the heat medium circulation system (16).