Energy-saving and consumption-reducing acetic acid preparation system
Patent Information
- Application Number
- CN202522138116.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-10
- Publication Date
- 2026-10-16
- Estimated Expiration
- 2035-10-10
AI Technical Summary
这些精馏提纯的工序需要消耗大量能量，大大增加了生产成本
1、反应器采出的部分粗产物依次在成品再沸器和废热锅炉中换热，从而依次加热成品塔塔釜物料以及废热锅炉蒸汽管线中的蒸汽，由此，可以实现反应余热的闭环回收，同时可以利用该余热对成品塔塔釜进行加热提高能量利用率；
Smart Images
Figure CN224854216U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of acetic acid preparation technology, and more specifically, to an energy-saving and consumption-reducing acetic acid preparation system. Background Technology
[0002] Acetic acid, also known as acetic acid, is a basic organic chemical raw material. Its derivatives are widely used in key sectors of the national economy, such as pharmaceuticals, pesticides, and food. The methanol carbonylation method, which emerged in the 1960s, revolutionized acetic acid production. This technology uses methanol and carbon monoxide as raw materials and achieves a highly efficient carbonylation reaction through a rhodium-based or iridium-based catalyst system. It boasts significant advantages such as high atom economy, mild reaction conditions, and excellent product purity, and has become the mainstream technology in modern acetic acid production.
[0003] Because the crude product after the acetic acid reaction is quite complex, it typically contains acetic acid, water, iodomethane, and other byproducts. To ensure product purity, the crude product needs to be purified by distillation. These distillation purification processes consume a large amount of energy, significantly increasing production costs.
[0004] In view of the above, this utility model is hereby proposed. Utility Model Content
[0005] The purpose of this invention is to provide an energy-saving and consumption-reducing acetic acid preparation system. This system uses the waste heat of the reactor material as the heat source of the bottom of the finished product tower, and uses the waste heat of the reactor material and the waste heat at the top of the finished product tower as the heat source of the bottom of the light-removal tower. Thus, a closed-loop recovery and utilization of the system's waste heat can be achieved, improving energy utilization efficiency, while reducing the amount of external energy input and lowering production costs.
[0006] In order to achieve the above-mentioned objectives of this utility model, the following technical solution is adopted: This utility model provides an energy-saving and consumption-reducing acetic acid preparation system, comprising: a carbon monoxide pipeline, a raw material methanol pipeline, a reactor, a light-light-removal tower, and a product tower; the carbon monoxide pipeline and the raw material methanol pipeline are both connected to the reactor; the side wall outlet of the light-light-removal tower is connected to the product tower; a product reboiler is provided inside the product tower; A portion of the crude product collected from the material outlet on the side wall of the reactor is fed into the light product removal tower, and the other portion is used as a heat source to exchange heat in the finished product reboiler and the waste heat boiler in sequence before flowing back to the reactor. The light-weight product removal tower is equipped with a light-weight product removal reboiler and a light-weight product removal supplementary reboiler. The material inlet of the light-weight product removal reboiler is connected to the bottom of the light-weight product removal tower, and the material outlet is connected to the side wall of the light-weight product removal tower. The material inlet of the light-weight product removal supplementary reboiler is connected to the bottom of the light-weight product removal tower, and the material outlet is connected to the side wall of the light-weight product removal tower. The top steam discharged from the top outlet of the finished product tower is used as the heat source for the light-weight product removal reboiler. The steam pipeline of the waste heat boiler, after exchanging heat with the material output from the reactor, serves as the heat source for the light-weight product removal supplementary reboiler.
[0007] In the above technical solution, a portion of the crude product from the reactor undergoes heat exchange in the finished product reboiler and the waste heat boiler, thereby sequentially heating the material in the bottom of the finished product tower and the steam in the steam pipeline of the waste heat boiler. This achieves closed-loop recovery of reaction waste heat, which can also be used to heat the bottom of the finished product tower, improving energy efficiency. Furthermore, the crude product, after heat exchange, flows back from the top of the reactor, exchanging heat with the top tail gas during its descent. This causes methanol in the tail gas to condense back into the liquid phase and return to the reactor with the reflux material to continue participating in the reaction, which helps improve the conversion rate of the reaction feedstock. The waste heat from the top of the finished product tower and the steam in the steam pipeline are thermally coupled to the bottom of the light-light product removal tower through the light-light product removal reboiler and the light-light product removal supplementary reboiler, respectively, further utilizing the reaction waste heat and the waste heat from the top of the finished product tower. In summary, this solution achieves closed-loop recovery and utilization of reaction waste heat and waste heat from the top of the finished product tower, improving energy efficiency while reducing the amount of external steam used for heating, lowering production costs, and achieving energy-saving and consumption-reducing acetic acid production.
[0008] In the above scheme, the crude product first serves as the heat source for the finished product reboiler, exchanging heat with the bottom material of the finished product tower before entering the waste heat boiler and steam in the steam pipeline for further heat exchange. This "cascade heat exchange" setup is a highly efficient energy recovery and process optimization design with multiple core benefits: the crude product first powers the finished product reboiler, meeting the heat requirements of the finished product tower for the vaporization and distillation of the bottom material, replacing the traditional external heat source consumption, while its own temperature is initially reduced to adapt to subsequent processing; after powering the finished product reboiler, the residual heat remaining in the crude product can be further transferred to steam in the waste heat boiler. This heated steam can be recycled as a heat source for other process units such as the light product removal tower supplementary reboiler, realizing the full cascade utilization of the crude product waste heat from high grade to medium grade, avoiding energy waste. In addition, this setup can reduce the problem of excessive local temperature difference caused by single heat exchange by releasing the heat of crude products in stages, reduce equipment thermal shock, extend the life of heat exchangers and waste heat boilers, and at the same time significantly reduce the consumption of external fresh steam, fuel and other energy, reduce the total energy consumption and production cost of the unit, reduce pollutant emissions, and take into account process stability, economy and environmental protection.
[0009] Preferably, the system further includes an evaporator, through which the crude product output from the reactor is processed and fed into the light product removal tower; the evaporator bottom is equipped with an evaporator-reboiler, and the steam pipeline of the waste heat boiler serves as the heat source for the evaporator-reboiler after exchanging heat with the material output from the reactor.
[0010] This scheme processes the crude product from the reactor through a sequentially arranged evaporator, light component removal tower, and product tower. This process can gradually separate impurities, recover resources, and enrich the target product, laying the foundation for obtaining high-purity acetic acid. At the same time, the waste heat recovered from the reactor in the steam pipeline can be used as a heat source for the evaporator-reboiler, further realizing closed-loop waste heat recovery, reducing energy waste, and lowering production costs.
[0011] Preferably, the product tower sidewall outlet is connected to a product pipeline, the raw material methanol pipeline is thermally coupled to the product heat exchanger, and the methanol in the raw material methanol pipeline is fed into the reactor after exchanging heat with the product in the product pipeline.
[0012] In the above scheme, the waste heat of the product is used to preheat the methanol in the raw methanol pipeline. This can not only promote the methanol entering the reactor to reach the reaction temperature quickly, but also reduce the cooling water consumption for product cooling, realizing "two-way utilization of one heat", reducing the total energy consumption and cost of the unit. Moreover, this method can improve process efficiency and reaction stability. The temperature of the preheated methanol is close to the reaction temperature, so it does not need to absorb a large amount of heat to raise the temperature after entering the reactor. This shortens the preheating time to extend the effective reaction time and improve the conversion rate. It can also avoid local temperature fluctuations in the reactor caused by cold methanol feed, reduce side reactions such as dimethyl ether and propionic acid, and reduce the load of subsequent distillation and separation.
[0013] Preferably, the bottom outlet of the product column is connected to the stripping column, and the top outlet of the stripping column is connected to the product column; A stripping reboiler is provided on the outside of the stripping column. The inlet of the stripping reboiler is connected to the bottom of the stripping column, and the outlet is connected to the side wall of the stripping column. The steam pipeline is connected to the stripping reboiler.
[0014] The stripping column can deeply heat and vaporize the material discharged from the bottom of the rectification column, achieving the final separation of light and heavy components. This ensures that the purity of the heavy components (or target product) at the bottom of the column meets the standards, while also recovering usable light components, thus avoiding resource waste. Simultaneously, by utilizing the waste heat recovered from the reaction in the steam pipeline as a heat source for the stripping reboiler, a closed-loop waste heat recovery can be achieved, reducing energy waste and lowering production costs.
[0015] Preferably, the tail gas outlet at the top of the reactor is connected to a high-pressure separator, the gas phase outlet at the top of the high-pressure separator is connected to a high-pressure absorption tower, and the bottom outlet of the high-pressure absorption tower is connected to a methanol absorption storage tank; the bottom outlet of the methanol absorption storage tank is connected to the reactor; the tail gas outlet at the top of the high-pressure absorption tower is connected to a high-pressure absorption tail gas cooler, and after the tail gas at the top of the high-pressure absorption tower is cooled by the high-pressure absorption tail gas cooler, the gas phase is discharged, and the liquid phase is returned to the high-pressure absorption tower. The high-pressure absorption tower can further absorb the heavy phase in the tail gas, which helps to further improve the raw material utilization rate.
[0016] Preferably, the bottom outlet of the methanol absorption storage tank is connected to a regeneration tower; the bottom outlet of the regeneration tower is connected to a reactor; a regeneration reboiler is installed on the outside of the regeneration tower; the material inlet of the regeneration reboiler is connected to the bottom of the regeneration tower, and the material outlet is connected to the side wall of the regeneration tower. By utilizing the waste heat recovered from the waste heat boiler as the heat source for the regeneration reboiler, the amount of external steam introduced into the regeneration reboiler can be reduced, further reducing production costs.
[0017] Preferably, the top tail gas outlet of the light phase removal tower is connected to a low-pressure absorption tower; the bottom outlet of the low-pressure absorption tower is connected to the methanol absorption storage tank, and the top gas phase outlet of the methanol absorption storage tank is connected to the low-pressure absorption tower. The low-pressure absorption tower can further absorb the heavy phase in the tail gas of the light phase removal tower, avoiding waste.
[0018] Preferably, the top tail gas outlet of the light-duty gas removal tower is connected to a light-duty gas removal primary cooler, the top gas phase outlet of the primary cooler is connected to a light-duty gas removal final cooler, the bottom liquid phase outlet of the primary cooler is connected to a separator, the middle outlet of the separator is connected to the light-duty gas removal tower, and the bottom outlet of the separator is connected to the reactor; the top gas phase outlet of the final cooler is connected to the low-pressure absorption tower, and the bottom liquid phase outlet is connected to the separator. By separately setting up the primary cooler, final cooler, and separator, the tail gas at the top of the light-duty gas removal tower can be staged, condensed, and recovered. This not only helps to improve the utilization rate of raw materials but also helps to promote the compliance of the tail gas at the top of the light-duty gas removal tower with emission standards.
[0019] Preferably, a reaction tail gas cooler is provided between the reactor and the high-pressure separator, and the tail gas outlet at the top of the reactor is connected to the high-pressure separator via the reaction tail gas cooler. By using a reaction tail gas cooler to pre-cool the reaction tail gas, the high-pressure separation efficiency can be improved, while avoiding the high temperature of the tail gas from generating additional load on the high-pressure separator, thus ensuring the service life of the high-pressure separator.
[0020] Preferably, the overhead vapor discharged from the top outlet of the finished product column is input into the heat source inlet of the light-weight component removal reboiler, and the heat source outlet of the light-weight component removal reboiler is connected to the finished product reflux tank. The top outlet of the finished product reflux tank is connected to the low-pressure absorption tower, and the bottom outlet is connected to the finished product column. The overhead vapor from the top of the finished product column flows into the finished product reflux tank after being cooled by heat exchange in the light-weight component removal reboiler. The liquid phase at the bottom of the finished product reflux tank can be returned to the finished product column for further distillation and separation, which can improve product yield and avoid waste.
[0021] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. A portion of the crude product collected from the reactor is sequentially heat-exchanged in the finished product reboiler and the waste heat boiler, thereby sequentially heating the material in the bottom of the finished product tower and the steam in the steam pipeline of the waste heat boiler. This enables closed-loop recovery of the reaction waste heat, and the waste heat can be used to heat the bottom of the finished product tower to improve energy utilization. 2. The crude product after heat exchange is refluxed from the top of the reactor. During the fall, it can exchange heat with the tail gas at the top, causing the methanol in the tail gas to condense back into the liquid phase and return to the reactor with the refluxed material to continue participating in the reaction. This helps to improve the conversion rate of the reaction raw materials. 3. The waste heat at the top of the finished product tower and the steam in the steam pipeline are thermally coupled to the bottom of the light-weight removal tower through the light-weight removal reboiler and the light-weight removal supplementary reboiler, respectively, so as to further utilize the waste heat of the reaction and the waste heat at the top of the finished product tower. 4. This scheme can realize closed-loop recovery and utilization of reaction waste heat and waste heat at the top of the finished product tower, improve energy utilization efficiency, and at the same time reduce the amount of external steam introduced for heating, thereby reducing production costs. Attached Figure Description
[0022] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A schematic diagram of the system according to Embodiment 1 of this utility model is shown; Figure 2 Show Figure 1 A partial schematic diagram of part A in the middle; Figure 3 Show Figure 1 A partial schematic diagram of part B.
[0023] In the diagram: 1. Carbon monoxide pipeline; 2. Reactor; 3. Reactor tail gas cooler; 4. Waste heat boiler; 5. High-pressure separator; 6. Steam pipeline; 7. Evaporator; 8. Evaporator-reboiler; 9. Raw material methanol pipeline; 10. Product heat exchanger; 11. Product cooler; 12. Product pipeline; 13. Light weight removal tower; 14. Light weight removal supplementary reboiler; 15. Light weight removal reboiler; 16. Acetic acid collection tank; 17. Light weight removal primary cooler; 18. Separator; 19. Light weight removal final cooler; 20. Finished product. Reflux tank; 21. Finished product tail gas cooler; 22. Finished product tower; 23. Finished product reboiler; 24. Stripping tower; 25. Stripping reboiler; 26. First low-temperature methanol pipeline; 27. High-pressure absorption tail gas cooler; 28. High-pressure absorption tower; 29. Low-pressure absorption tower; 30. Methanol cooler; 31. Methanol absorption storage tank; 32. Regeneration tower; 33. Regeneration tail gas cooler; 34. Regeneration reboiler; 35. Lean liquor cooler; 36. Methanol lean liquor tank; 37. Second low-temperature methanol pipeline. Detailed Implementation
[0024] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some embodiments of this utility model, not all embodiments, and are only used to illustrate this utility model, and should not be regarded as limiting the scope of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.
[0025] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0026] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0027] To more clearly illustrate the technical solution of this utility model, the following description is provided in the form of specific embodiments.
[0028] Example 1 See also Figure 1-3 This embodiment provides an energy-saving and consumption-reducing acetic acid preparation system, which includes: a carbon monoxide pipeline 1, a raw material methanol pipeline 9, a reactor 2, a light-light-removal tower 13, and a finished product tower 22; both the carbon monoxide pipeline 1 and the raw material methanol pipeline 9 are connected to the reactor 2; the side wall outlet of the light-light-removal tower 13 is connected to the finished product tower 22; a finished product reboiler 23 is installed inside the finished product tower 22. In this embodiment, an acetic acid collection tank 16 is provided between the light-light-removal tower 13 and the finished product tower 22, the side wall outlet of the light-light-removal tower 13 is connected to the top inlet of the acetic acid collection tank 16, and the bottom outlet of the acetic acid collection tank 16 is connected to the finished product tower 22.
[0029] A portion of the crude product collected from the material outlet on the side wall of reactor 2 is fed into the light product removal tower 13, while the other portion, as a heat source, is exchanged in the finished product reboiler 23 and the waste heat boiler 4 before flowing back to reactor 2.
[0030] A light-weight removal reboiler 15 and a light-weight removal supplementary reboiler 14 are installed outside the light-weight removal tower 13. The material inlet of the light-weight removal reboiler 15 is connected to the bottom of the light-weight removal tower 13, and the material outlet is connected to the side wall of the light-weight removal tower 13. The material inlet of the light-weight removal supplementary reboiler 14 is connected to the bottom of the light-weight removal tower 13, and the material outlet is connected to the side wall of the light-weight removal tower 13. The top steam discharged from the top outlet of the finished product tower 22 is used as the heat source for the light-weight removal reboiler 15. Specifically, the top steam discharged from the top outlet of the finished product tower 22 is input into the heat source inlet of the light-weight removal reboiler 15, and the heat source outlet of the light-weight removal reboiler 15 is connected to the finished product reflux tank 20. The bottom outlet of the finished product reflux tank 20 is connected to the finished product tower 22, and the top outlet is connected to the low-pressure absorption tower 29. The top gas phase of the finished product reflux tank 20 is cooled by the finished product tail gas cooler 21 and then sent to the low-pressure absorption tower 29. The steam pipeline 6 of the waste heat boiler 4 is used as the heat source for the light-weight removal supplementary reboiler 14 after exchanging heat with the material output from the reactor 2.
[0031] It is understandable that pumps and valves can be installed on pipelines as needed to facilitate material flow and control, which will not be elaborated upon here.
[0032] To facilitate the addition of catalyst, a catalyst pipeline can be installed. This pipeline can be directly connected to reactor 2 or indirectly connected to reactor 2 through other pipelines, which will not be elaborated here.
[0033] In this embodiment, the sidewall of the finished product tower 22 can also be connected to a potassium hydroxide pipeline for inputting potassium hydroxide to avoid residual trace acidic impurities (especially halide impurities) in the tower from corroding the equipment, contaminating the product, or affecting subsequent processes. This will not be elaborated further.
[0034] See also Figure 1 , 2 The system also includes an evaporator 7. The crude product output from reactor 2 is processed by the evaporator 7 and then fed into the light product removal tower 13. The bottom of the evaporator 7 is equipped with an evaporator-reboiler 8. The steam pipeline 6 of the waste heat boiler 4, after exchanging heat with the material output from reactor 2, serves as the heat source for the evaporator-reboiler 8. The crude product enters the evaporator 7, is heated by the evaporator-reboiler 8, and the top gas phase enters the light product removal tower 13, while the bottom liquid phase is refluxed back to reactor 2.
[0035] like Figure 3 As shown, the product tower 22 has a product pipeline 12 connected to its side wall outlet. The raw material methanol pipeline 9 is thermally coupled to the product pipeline 12 via the product heat exchanger 10. The methanol in the raw material methanol pipeline 9 exchanges heat with the product in the product pipeline 12 before being fed into the reactor 2. Specifically, the product in the product pipeline 12 is cooled by the product cooler 11 after passing through the product heat exchanger 10 before being output.
[0036] Continue reading Figure 3 The bottom outlet of the product column 22 is connected to the stripping column 24, and the top outlet of the stripping column 24 is connected to the product column 22. A stripping reboiler 25 is provided on the outside of the stripping column 24. The inlet of the stripping reboiler 25 is connected to the bottom of the stripping column 24, and the outlet is connected to the side wall of the stripping column 24. The steam pipeline 6 is connected to the stripping reboiler 25.
[0037] See also Figure 1 , 3 The tail gas outlet at the top of reactor 2 is connected to high-pressure separator 5. A reaction tail gas cooler 3 is installed between reactor 2 and high-pressure separator 5. The tail gas outlet at the top of reactor 2 is connected to high-pressure separator 5 via reaction tail gas cooler 3. The gas phase outlet at the top of high-pressure separator 5 is connected to high-pressure absorption tower 28. The bottom outlet of high-pressure absorption tower 28 is connected to methanol absorption storage tank 31. The bottom outlet of methanol absorption storage tank 31 is connected to reactor 2. The tail gas outlet at the top of high-pressure absorption tower 28 is connected to high-pressure absorption tail gas cooler 27. After being cooled by high-pressure absorption tail gas cooler 27, the gas phase of the tail gas from the top of high-pressure absorption tower 28 is discharged and sent to the flare system for incineration, while the liquid phase is returned to high-pressure absorption tower 28.
[0038] Continue reading Figure 3The bottom outlet of the methanol absorption storage tank 31 is connected to the regeneration tower 32; the bottom outlet of the regeneration tower 32 is connected to the reactor 2; a regeneration reboiler 34 is installed on the outside of the regeneration tower 32; the material inlet of the regeneration reboiler 34 is connected to the bottom of the regeneration tower 32, and the material outlet is connected to the side wall of the regeneration tower 32. The tail gas at the top of the regeneration tower 32 is treated by the regeneration tail gas cooler 33, and the gas phase is sent to the light-duty removal final cooler 19, while part of the liquid phase returns to the regeneration tower 32, and the other part is sent to the reactor 2 to continue participating in the reaction. The material at the bottom of the regeneration tower 32 is cooled by the lean liquid cooler 35 and then sent to the methanol lean liquid tank 36. The methanol in the methanol lean liquid tank 36 can be returned to the reactor 2 to continue participating in the reaction. In this embodiment, part of the material at the bottom of the methanol absorption storage tank 31 is sent to the regeneration tower 32 for treatment, and the other part is sent to the reactor 2 to continue participating in the reaction.
[0039] See also Figure 2 , 3 The tail gas outlet at the top of the light gas removal tower 13 is connected to the low-pressure absorption tower 29; the bottom outlet of the low-pressure absorption tower 29 is connected to the methanol absorption storage tank 31, and the top gas phase outlet of the methanol absorption storage tank 31 is connected to the low-pressure absorption tower 29. The tail gas at the top of the low-pressure absorption tower 29 is sent to the flare system for incineration.
[0040] To facilitate the absorption of methanol in the gas phase by the high-pressure absorption tower 28 and the low-pressure absorption tower 29, in this embodiment, low-temperature methanol can be introduced into the two absorption towers through pipelines. Specifically, low-temperature methanol can be introduced into the high-pressure absorption tower 28 through the first low-temperature methanol pipeline 26, and into the low-pressure absorption tower 29 through the second low-temperature methanol pipeline 37. A high-pressure absorption methanol cooler 30 can be installed on the second low-temperature methanol pipeline 37, which will not be described in detail.
[0041] In this embodiment, the methanol sources of the raw material methanol pipeline 9, the first low-temperature methanol pipeline 26, and the second low-temperature methanol pipeline 37 can be the same or different. For example, the inlets of the three methanol pipelines can be connected to the same methanol storage tank.
[0042] like Figure 2 As shown, the top tail gas outlet of the light-weight gas removal tower 13 is connected to the light-weight gas removal primary cooler 17, the top gas phase outlet of the primary cooler 17 is connected to the light-weight gas removal final cooler 19, and the bottom liquid phase outlet of the primary cooler 17 is connected to the separator 18. The middle outlet of the separator 18 is connected to the light-weight gas removal tower 13, and the bottom outlet is connected to the reactor 2. The top gas phase outlet of the final cooler 19 is connected to the low-pressure absorption tower 29, and the bottom liquid phase outlet is connected to the separator 18. After the tail gas at the top of the light-weight gas removal tower 13 is cooled by the primary cooler 17, the liquid phase enters the separator 18, and the gas phase enters the final cooler 19 for cooling. The gas phase obtained from the final cooler 19 enters the low-pressure absorption tower 29, while the liquid phase enters the separator 18. The material in the middle of the separator 18 enters the light-weight gas removal tower 13, while the heavy phase separated at the bottom flows to the reactor 2 to continue participating in the reaction.
[0043] In this embodiment, the steam line 6 provides heat sources for the evaporator reboiler 8, the light-weight reboiler 15, the stripping reboiler 25, and the regenerator reboiler 34. Specifically, the steam line 6 can be connected to each reboiler through multiple parallel branches, so that each reboiler can be heated separately.
[0044] In this embodiment, methanol, carbon monoxide, and catalyst / co-catalyst are introduced into the reactor (2.8 MPa, 188°C) in a certain proportion for reaction. A portion of the reaction liquid (2.8 MPa, 188°C) is pumped into the inlet of the product reboiler tube side, where it exchanges heat with the circulating liquid in the product tower bottom (0.23 MPa, 163°C). After further heat extraction using a waste heat boiler, it returns to the reactor. The waste heat boiler then produces steam at ~175°C (0.9 MPa) to heat the remaining reboilers (evaporation reboiler, light component removal reboiler, stripping reboiler, and regeneration reboiler). Another portion of the reaction liquid undergoes flash evaporation in the evaporator. The gas phase (acetic acid, water, iodomethane, etc.) enters the light component removal tower (0.1 MPa, 141°C) for light component removal and dehydration, while the liquid phase (acetic acid, water, catalyst, etc.) returns to the reactor to continue participating in the reaction. The upper part of the light component removal tower removes light components such as iodomethane, CO, and water. Crude acetic acid from the side stream enters the product column (0.18 MPa, 154 °C) for further distillation. The bottom of the column (acetic acid, catalyst, etc.) is returned to the reactor via an evaporator. The top vapor (0.18 MPa, 154 °C) from the top of the product column is used to heat the circulating liquid in the bottom of the light-removal column (0.1 MPa, 141 °C). The product acetic acid (>99.9 wt.%) is collected from the column body and used to preheat the raw material methanol. The bottom liquid enters the stripping column (to further separate acetic acid and propionic acid). The high-pressure absorption column and the low-pressure absorption column are used for tail gas absorption and recovery of iodomethane, which is then returned to the reaction system.
[0045] Testing revealed that the system in this embodiment requires 8.74 kcal for heating the bottom of the light product removal column, 8.33 kcal for the bottom of the product column, and 0.01 kcal for the bottom of the stripping column, totaling 17.1 kcal. The crude product in the reactor provides 8.33 kcal through heat exchange in the product reboiler, the waste heat boiler recovers 2.62 kcal, and the top steam from the product column provides 7.95 kcal, for a total of 18.9 kcal. This meets the heat requirements of the entire product rectification stage (i.e., the crude product is processed through the evaporator, light product removal column, product column, and stripping column), and excess heat can be used in the regeneration column, reducing the amount of external steam required for the recovery stage and lowering production costs.
[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.
Claims
1. An energy-saving and consumption-reducing acetic acid preparation system, characterized in that, It includes: a carbon monoxide pipeline, a raw material methanol pipeline, a reactor, a light-light product removal tower, and a finished product tower; the carbon monoxide pipeline and the raw material methanol pipeline are both connected to the reactor; the outlet of the side wall of the light-light product removal tower is connected to the finished product tower; a finished product reboiler is installed inside the finished product tower; A portion of the crude product collected from the material outlet on the side wall of the reactor is fed into the light product removal tower, and the other portion is used as a heat source to exchange heat in the finished product reboiler and the waste heat boiler in sequence before flowing back to the reactor. The light-weight product removal tower is equipped with a light-weight product removal reboiler and a light-weight product removal supplementary reboiler. The material inlet of the light-weight product removal reboiler is connected to the bottom of the light-weight product removal tower, and the material outlet is connected to the side wall of the light-weight product removal tower. The material inlet of the light-weight product removal supplementary reboiler is connected to the bottom of the light-weight product removal tower, and the material outlet is connected to the side wall of the light-weight product removal tower. The top steam discharged from the top outlet of the finished product tower is used as the heat source for the light-weight product removal reboiler. The steam pipeline of the waste heat boiler, after exchanging heat with the material output from the reactor, serves as the heat source for the light-weight product removal supplementary reboiler.
2. The system according to claim 1, characterized in that, It also includes an evaporator, through which the crude product output from the reactor is processed and fed into the light product removal tower; the bottom of the evaporator tower is equipped with an evaporator-reboiler, and the steam pipeline of the waste heat boiler serves as the heat source for the evaporator-reboiler after exchanging heat with the material output from the reactor.
3. The system according to claim 1, characterized in that, The product tower sidewall outlet is connected to a product pipeline. The raw material methanol pipeline is thermally coupled with the product heat exchanger. After heat exchange between the methanol in the raw material methanol pipeline and the product in the product pipeline, it is fed into the reactor.
4. The system according to claim 1, characterized in that, The bottom outlet of the finished product tower is connected to the stripping tower, and the top outlet of the stripping tower is connected to the finished product tower. A stripping reboiler is provided on the outside of the stripping column. The inlet of the stripping reboiler is connected to the bottom of the stripping column, and the outlet is connected to the side wall of the stripping column. The steam pipeline is connected to the stripping reboiler.
5. The system according to claim 1, characterized in that, The tail gas outlet at the top of the reactor is connected to a high-pressure separator, the gas phase outlet at the top of the high-pressure separator is connected to a high-pressure absorption tower, and the bottom outlet of the high-pressure absorption tower is connected to an absorption methanol storage tank. The bottom outlet of the absorption methanol storage tank is connected to the reactor. The tail gas outlet at the top of the high-pressure absorption tower is connected to a high-pressure absorption tail gas cooler. After the tail gas at the top of the high-pressure absorption tower is cooled by the high-pressure absorption tail gas cooler, the gas phase is discharged and the liquid phase is returned to the high-pressure absorption tower.
6. The system according to claim 5, characterized in that, The bottom outlet of the methanol absorption storage tank is connected to the regeneration tower; the bottom outlet of the regeneration tower is connected to the reactor; a regeneration reboiler is provided on the outside of the regeneration tower; the material inlet of the regeneration reboiler is connected to the bottom of the regeneration tower, and the material outlet is connected to the side wall of the regeneration tower.
7. The system according to claim 5, characterized in that, The tail gas outlet at the top of the light gas removal tower is connected to the low-pressure absorption tower; the bottom outlet of the low-pressure absorption tower is connected to the methanol absorption storage tank, and the gas phase outlet at the top of the methanol absorption storage tank is connected to the low-pressure absorption tower.
8. The system according to claim 7, characterized in that, The tail gas outlet at the top of the light-duty gas removal tower is connected to the light-duty gas removal primary cooler; the gas phase outlet at the top of the light-duty gas removal primary cooler is connected to the light-duty gas removal final cooler; the liquid phase outlet at the bottom of the light-duty gas removal primary cooler is connected to the separator; the middle outlet of the separator is connected to the light-duty gas removal tower; and the bottom outlet of the separator is connected to the reactor. The gas phase outlet at the top of the light-duty gas removal final cooler is connected to the low-pressure absorption tower; and the liquid phase outlet at the bottom is connected to the separator.
9. The system according to claim 5, characterized in that, A reaction tail gas cooler is provided between the reactor and the high-pressure separator, and the tail gas outlet at the top of the reactor is connected to the high-pressure separator via the reaction tail gas cooler.
10. The system according to claim 7, characterized in that, The top steam discharged from the top outlet of the finished product tower is input into the heat source inlet of the light-weight reboiler, and the heat source outlet of the light-weight reboiler is connected to the finished product reflux tank; the top outlet of the finished product reflux tank is connected to the low-pressure absorption tower, and the bottom outlet is connected to the finished product tower.