Low energy consumption acetic acid production system

Abstract

The utility model provides a kind of low energy consumption acetic acid production system, and the system includes: reaction unit and product rectification unit;Reaction unit includes raw material methanol delivery pipeline, carbon monoxide pipeline and reactor;Carbon monoxide pipeline is connected reactor;Part of crude product in reactor side line export is reflowed to reactor top after being absorbed waste heat via waste heat boiler, and another part is exported via product pipeline after being handled via product rectification unit;Steam pipeline of waste heat boiler provides heat source for reboiler in product rectification unit after being exchanged heat with crude product of reactor;Raw material methanol delivery pipeline is thermally coupled with product pipeline by methanol feed heat exchanger, and methanol in raw material methanol delivery pipeline is input reactor after being exchanged heat with product in product pipeline.The system is helpful to realize low energy consumption acetic acid production.

Description

Technical Field

[0001] This utility model relates to the field of acetic acid preparation technology, and more specifically, to a low-energy acetic acid production 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 a low-energy acetic acid production system. This system utilizes a waste heat boiler to recover waste heat from the reaction section and uses the recovered waste heat as the heat source for each reboiler in the product distillation unit. This helps to improve energy utilization, realize the reuse of waste heat in the product distillation process, and reduce the amount of external energy input, thereby reducing costs.

[0006] In order to achieve the above-mentioned objectives of this utility model, the following technical solution is adopted: This utility model provides a low-energy acetic acid production system, including: a reaction unit and a product distillation unit; the reaction unit includes a raw material methanol conveying pipeline, a carbon monoxide pipeline and a reactor; the carbon monoxide pipeline is connected to the reactor; A portion of the crude product collected from the side outlet of the reactor is returned to the top of the reactor after absorbing waste heat in the waste heat boiler, while the other portion is processed by the product distillation unit and output through the product pipeline; the steam pipeline of the waste heat boiler provides a heat source for the reboiler in the product distillation unit after exchanging heat with the crude product of the reactor. The raw material methanol delivery pipeline is thermally coupled to the product pipeline through a methanol feed heat exchanger. The methanol in the raw material methanol delivery pipeline exchanges heat with the product in the product pipeline before being fed into the reactor.

[0007] In the above technical solution, by coordinating the design of the waste heat boiler, reactor, and reboiler in the product distillation unit, the waste heat of the crude product in the reactor can be reused during the product distillation process. This not only achieves closed-loop recovery of waste heat and improves energy utilization, but also reduces energy loss, reduces the amount of external steam introduced for heating, and lowers production costs. In addition, the cooled and refluxed crude product can exchange heat with the top tail gas as it falls from the top, causing the 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. This helps to improve the conversion rate of the reaction feedstock.

[0008] Preferably, the product distillation unit includes a product column; the side outlet of the product column is connected to the product pipeline; the reboiler in the product distillation unit includes a product reboiler; the inlet of the product reboiler is connected to the bottom of the product column, and the outlet is connected to the side wall of the product column; the steam pipeline of the waste heat boiler is connected to the product reboiler as a reboiling heat source.

[0009] In the above scheme, the reboiler at the bottom of the finished product column (i.e., the finished product reboiler) can provide heat for the distillation of the material in the finished product column. This scheme utilizes the waste heat recovered from the waste heat boiler as the reboiling heat source for the finished product reboiler, which can achieve closed-loop waste heat recovery, further improve energy utilization, and at the same time reduce the amount of external steam supply, thereby reducing production costs.

[0010] Preferably, the product distillation unit further includes an evaporator, a light-light product removal tower, and a dehydration tower connected in sequence. The crude product collected from the reactor side stream is processed sequentially through the evaporator, the light-light product removal tower, the dehydration tower, and the product tower before being output through the product pipeline. The reboiler in the product distillation unit further includes an evaporation reboiler, a light-weight reboiler, and a dehydration reboiler; the evaporation reboiler is located in the bottom of the evaporator; the inlet of the light-weight reboiler is connected to the bottom of the light-weight removal column, and the outlet is connected to the side wall of the light-weight removal column; the inlet of the dehydration reboiler is connected to the bottom of the dehydration column, and the outlet is connected to the side wall of the dehydration column; the steam pipeline of the waste heat boiler is connected to the evaporation reboiler, the light-weight reboiler, and the dehydration reboiler respectively to serve as a reboiling heat source.

[0011] This scheme, by setting up an evaporator, a light component removal tower, and a dehydration tower, can gradually separate impurities, recover resources, and enrich the target product, laying the foundation for finally obtaining high-purity acetic acid. By utilizing the waste heat recovered from the waste heat boiler as the heat source for the evaporation reboiler, light component removal reboiler, and dehydration reboiler, closed-loop waste heat recovery can be achieved, reducing energy waste and lowering production costs.

[0012] Preferably, the product distillation unit further includes a stripping column; 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; The reboiler in the product distillation unit also includes a stripping reboiler; 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 of the waste heat boiler is connected to the stripping reboiler.

[0013] The above scheme, by setting up a stripping column, can deeply heat and vaporize the "heavy fraction containing trace amounts of light components" discharged from the bottom of the distillation column, achieving the final separation of light and heavy components. This ensures that the purity of the heavy fraction (or target product) at the bottom of the column meets the standards, while also recovering usable light components, thus avoiding resource waste. By utilizing the waste heat recovered from the waste heat boiler as the heat source for the stripping reboiler, a closed-loop waste heat recovery can be achieved, reducing energy waste and lowering production costs.

[0014] Preferably, the system further includes a recovery unit, wherein the tail gas outlet at the top of the reactor and the tail gas outlet at the top of the light product removal tower are both connected to the recovery unit; the steam pipeline of the waste heat boiler provides a heat source for the reboiler in the recovery unit after exchanging heat with the crude product of the reactor. In the above scheme, the heat source for the reboiler in the recovery unit is mainly provided by the waste heat recovered from the waste heat boiler, which can further improve the waste heat utilization efficiency and reduce production costs.

[0015] Preferably, the recovery unit includes a high-pressure absorption tower and a methanol absorption storage tank; 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 the high-pressure absorption tower, and the bottom outlet of the high-pressure absorption tower is connected to the 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 recovery unit further includes a regeneration tower; the bottom outlet of the methanol absorption storage tank is connected to the regeneration tower, and the bottom outlet of the regeneration tower is connected to a lean methanol tank; the reboiler in the recovery unit includes a regeneration reboiler, the inlet of which is connected to the bottom of the regeneration tower, and the outlet of which 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, closed-loop waste heat recovery can be achieved, reducing energy waste and further lowering production costs.

[0017] Preferably, the recovery unit further includes a low-pressure absorption tower; the top tail gas outlet of the light phase 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 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 exhaust 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. This configuration enables staged condensation and recovery, efficient material circulation, and pretreatment of the exhaust gas to meet emission standards.

[0019] Preferably, the exhaust gas outlet at the top of the dehydration tower is connected to a dehydration cooler, the outlet of the dehydration cooler is connected to a dehydration reflux trough, and the bottom outlet of the dehydration reflux trough is connected to the dehydration tower. This helps improve material separation efficiency and avoids waste.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. By coordinating the design of the waste heat boiler, reactor, and reboiler in the product distillation unit, the waste heat of the crude product in the reactor can be reused in the product distillation process. This not only achieves closed-loop recovery of waste heat and improves energy utilization, but also reduces energy loss, reduces the amount of external steam introduced for heating, and lowers production costs. 2. During the cooling and reflux process, the crude product can exchange heat with the top tail gas as it falls from the top, causing the 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. This helps to improve the conversion rate of the reaction raw materials. Attached Figure Description

[0021] 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 magnified view of part A in the middle; Figure 3 Show Figure 1 A magnified view of part B in the middle section.

[0022] In the diagram: 1. Methanol feed pipeline; 2. Methanol intermediate storage tank; 3. High-pressure methanol delivery pipeline; 4. Low-pressure methanol delivery pipeline; 5. Raw material methanol delivery pipeline; 6. Methanol feed heat exchanger; 7. Product cooler; 8. Product pipeline; 9. Carbon monoxide pipeline; 10. Reactor; 11. Reactor tail gas cooler; 12. High-pressure separator; 13. Waste heat boiler; 14. Evaporator; 15. Evaporator-reboiler; 16. Light weight removal tower; 17. Light weight removal reboiler; 18. Acetic acid collection tank; 19. Light weight removal primary cooler; 20. Separator; 21. Light weight removal final cooler; 22. 23. Dehydration cooler; 24. Dehydration tower; 25. Dehydration reflux tank; 26. Dehydration reboiler; 27. Product tower; 28. Product tail gas cooler; 29. ​​Product reflux tank; 30. Product reboiler; 31. Stripping tower; 32. Stripping reboiler; 33. Make-up steam pipeline; 34. High-pressure absorption tail gas cooler; 35. High-pressure absorption tower; 36. High-pressure methanol absorption cooler; 37. Low-pressure absorption tower; 38. Methanol absorption storage tank; 39. Regeneration tower; 40. Regeneration tail gas cooler; 41. Regeneration reboiler; 42. Lean liquor cooler; 43. Methanol lean liquor tank. Detailed Implementation

[0023] 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.

[0024] 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.

[0025] 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.

[0026] To more clearly illustrate the technical solution of this utility model, the following description is provided in the form of specific embodiments.

[0027] Example 1 See also Figure 1-3 This embodiment provides a low-energy acetic acid production system, including a reaction unit and a product distillation unit. The reaction unit includes a raw material methanol conveying pipeline 5, a carbon monoxide pipeline 9, and a reactor 10. The carbon monoxide pipeline 9 is connected to the reactor 10. A portion of the crude product collected from the side outlet of the reactor 10 is recycled back to the top of the reactor 10 after absorbing waste heat in a waste heat boiler 13, and the other portion is processed by the product distillation unit and output through the product pipeline 8. The steam pipeline of the waste heat boiler 13 provides a heat source for the reboiler in the product distillation unit after exchanging heat with the crude product of the reactor 10. The raw material methanol conveying pipeline 5 is thermally coupled to the product pipeline 8 through a methanol feed heat exchanger 6. The methanol in the raw material methanol conveying pipeline 5 exchanges heat with the product in the product pipeline 8 before being input into the reactor 10. The product in the product pipeline 8 is output after being cooled by a product cooler 7 after exchanging heat in the methanol feed heat exchanger 6. Carbon monoxide and methanol react in reactor 10. Part of the crude methanol product is refluxed after heat exchange with the steam pipeline in waste heat boiler 13, while the other part enters the product distillation unit for distillation.

[0028] 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.

[0029] To facilitate the addition of catalyst, a catalyst pipeline can also be installed. This pipeline can be directly connected to reactor 10 or indirectly connected to reactor 10 through other pipelines, which will not be elaborated here.

[0030] In this embodiment, the product distillation unit includes a product column 26; the side outlet of the product column 26 is connected to the product pipeline 8; the reboiler in the product distillation unit includes a product reboiler 29; the inlet of the product reboiler 29 is connected to the bottom of the product column 26, and the outlet is connected to the side wall of the product column 26; the steam pipeline of the waste heat boiler 13 is connected to the product reboiler 29 as a reboiling heat source. The material at the bottom of the product column 26 is heated by the product reboiler 29 and then refluxed.

[0031] To prevent residual trace acidic impurities (especially halide impurities) in the tower from corroding equipment, contaminating products, or affecting subsequent processes, the side wall of the finished product tower 26 can also be connected to a potassium hydroxide pipeline for inputting potassium hydroxide, which will not be elaborated here.

[0032] Continue reading Figure 1 The product distillation unit also includes an evaporator 14, a light-light product removal tower 16, and a dehydration tower 23 connected in sequence. The crude product collected from the side stream of the reactor 10 is processed sequentially through the evaporator 14, the light-light product removal tower 16, the dehydration tower 23, and the product tower 26 before being output through the product pipeline 8. An acetic acid collection tank 18 is provided between the light-light product removal tower 16 and the dehydration tower 23. The outlet of the side wall of the light-light product removal tower 16 is connected to the top inlet of the acetic acid collection tank 18, and the bottom outlet of the acetic acid collection tank 18 is connected to the dehydration tower 23. The reboilers in the product distillation unit also include an evaporation reboiler 15, a light-weight reboiler 17, and a dehydration reboiler 25. The evaporation reboiler 15 is located in the bottom of the evaporator 14. The inlet of the light-weight reboiler 17 is connected to the bottom of the light-weight removal tower 16, and the outlet is connected to the side wall of the light-weight removal tower 16. The inlet of the dehydration reboiler 25 is connected to the bottom of the dehydration tower 23, and the outlet is connected to the side wall of the dehydration tower 23. The steam pipeline of the waste heat boiler 13 is connected to the evaporation reboiler 15, the light-weight reboiler 17, and the dehydration reboiler 25 respectively to serve as a reboiling heat source.

[0033] See also Figure 1 , 3 The top tail gas outlet of the finished product column 26 is connected to the finished product tail gas cooler 27. The outlet of the finished product tail gas cooler 27 is connected to the finished product reflux trough 28. The bottom outlet of the finished product reflux trough 28 is connected to both the finished product column 26 and the dehydration column 23. The tail gas from the top of the finished product column 26 is cooled by the finished product tail gas cooler 27 and then enters the finished product reflux trough. Part of the material in the finished product reflux trough enters the finished product column 26 for further distillation, while the other part enters the dehydration column 23 for further processing.

[0034] like Figure 3 As shown, the product distillation unit also includes a stripping column 30; the bottom outlet of the product column 26 is connected to the stripping column 30, the top outlet of the stripping column 30 is connected to the product column 26, and the bottom outlet discharges acetic acid; the reboiler in the product distillation unit also includes a stripping reboiler 31; the inlet of the stripping reboiler 31 is connected to the bottom of the stripping column 30, and the outlet is connected to the side wall of the stripping column 30; the steam pipeline of the waste heat boiler 13 is connected to the stripping reboiler 31.

[0035] In this embodiment, the stripping reboiler 31 may be connected to a supplementary steam line 32 to meet the working requirements of the stripping reboiler 31.

[0036] See also Figure 1 , 3The system also includes a recovery unit, with the top tail gas outlet of reactor 10 and the top tail gas outlet of light product removal tower 16 both connected to the recovery unit; the steam pipeline of waste heat boiler 13 provides a heat source for the reboiler in the recovery unit after exchanging heat with the crude product of reactor 10.

[0037] In this embodiment, the recovery unit includes a high-pressure absorption tower 34 and a methanol absorption storage tank 37; the tail gas outlet at the top of the reactor 10 is connected to a high-pressure separator 12. Specifically, the tail gas at the top of the reactor 10 is cooled by the reaction tail gas cooler 11 and then enters the high-pressure separator 12 for separation. The gas phase outlet at the top of the high-pressure separator 12 is connected to the high-pressure absorption tower 34, and the bottom outlet of the high-pressure absorption tower 34 is connected to the methanol absorption storage tank 37; the bottom outlet of the methanol absorption storage tank 37 is connected to the reactor 10; the tail gas outlet at the top of the high-pressure absorption tower 34 is connected to a high-pressure absorption tail gas cooler 33. After being cooled by the high-pressure absorption tail gas cooler 33, the gas phase of the tail gas at the top of the high-pressure absorption tower 34 is discharged, and the liquid phase is returned to the high-pressure absorption tower 34. A high-pressure methanol delivery pipeline 3 is connected to the side wall of the high-pressure absorption tower 34, which is used to introduce low-temperature methanol into the high-pressure absorption tower 34. After being cooled by the high-pressure absorption tail gas cooler 33, the liquid phase of the tail gas at the top of the high-pressure absorption tower 34 is returned, and the gas phase is sent to the flare system for incineration.

[0038] The recovery unit also includes a regeneration tower 38; the bottom outlet of the methanol absorption storage tank 37 is connected to the regeneration tower 38, and the bottom outlet of the regeneration tower 38 is connected to the methanol lean liquor tank 42; the reboiler in the recovery unit includes a regeneration reboiler 40, the inlet of which is connected to the bottom of the regeneration tower 38, and the outlet of which is connected to the side wall of the regeneration tower 38. The tail gas from the top of the regeneration tower 38 is treated by the regeneration tail gas cooler 39, and the gas phase is sent to the light-duty removal final cooler 21, while part of the liquid phase is returned to the regeneration tower 38, and the other part is sent to the reactor 10 to continue participating in the reaction. The material at the bottom of the regeneration tower 38 is cooled by the lean liquor cooler 41 and then sent to the methanol lean liquor tank 42. The methanol in the methanol lean liquor tank 42 can be recycled back to the reactor 10 to continue participating in the reaction.

[0039] The recovery unit also includes a low-pressure absorption tower 36; the top tail gas outlet of the light-duty removal tower 16 is connected to the low-pressure absorption tower 36; the bottom outlet of the low-pressure absorption tower 36 is connected to the methanol absorption storage tank 37, and the top gas phase outlet of the methanol absorption storage tank 37 is connected to the low-pressure absorption tower 36. A low-pressure methanol conveying pipeline 4 is connected to the side wall of the low-pressure absorption tower 36, and a high-pressure methanol absorption cooler 35 is installed on the low-pressure methanol conveying pipeline 4. The low-pressure methanol conveying pipeline 4 is used to introduce low-temperature methanol into the low-pressure absorption tower 36. The tail gas at the top of the low-pressure absorption tower 36 is sent to the flare system for incineration. Part of the material at the bottom of the methanol absorption storage tank 37 is sent to the regeneration tower 38 for treatment, and the other part is sent to the reactor 10 to continue participating in the reaction.

[0040] In this embodiment, the inlets of the raw material methanol conveying pipeline 5, the high-pressure methanol conveying pipeline 3, and the low-pressure methanol conveying pipeline 4 are all connected to the intermediate methanol storage tank 2, and the top inlet of the intermediate methanol storage tank 2 is connected to the methanol feed pipeline 1.

[0041] In this embodiment, the top tail gas outlet of the light-duty carbon removal tower 16 is connected to the light-duty carbon removal pre-cooler 19, the top gas phase outlet of the light-duty carbon removal pre-cooler 19 is connected to the light-duty carbon removal final cooler 21, the bottom liquid phase outlet of the light-duty carbon removal pre-cooler 19 is connected to the separator 20, the middle outlet of the separator 20 is connected to the light-duty carbon removal tower 16, and the bottom outlet is connected to the reactor 10; the top gas phase outlet of the light-duty carbon removal final cooler 21 is connected to the low-pressure absorption tower 36, and the bottom liquid phase outlet is connected to the separator 20. The top tail gas outlet of the dehydration tower 23 is connected to the dehydration cooler 22, the outlet of the dehydration cooler 22 is connected to the dehydration reflux tank 24, and the bottom outlet of the dehydration reflux tank 24 is connected to the dehydration tower 23. The side wall of the separator 20 can also be connected to a demineralized water supply pipeline for replenishing demineralized water into the separator 20, which will not be described in detail.

[0042] The tail gas from the top of the light-weight gas removal tower 16 is cooled by the primary cooler 19. The liquid phase enters the separator 20, a portion of the gas phase enters the final cooler 21 for cooling, and the remaining portion enters the dehydration cooler 22. The gas phase obtained from the final cooler 21 enters the low-pressure absorption tower 36, while the liquid phase enters the separator 20. The material in the middle of the separator 20 enters the light-weight gas removal tower 16, while the heavy phase separated at the bottom flows to the reactor 10 to continue participating in the reaction. The tail gas from the top of the dehydration tower 23 is cooled by the dehydration cooler 22 and enters the dehydration reflux tank 24. The material at the bottom of the dehydration reflux tank 24 is returned to the dehydration tower 23.

[0043] 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; the reaction liquid is flash-evaporated through an evaporator, and the gas phase (acetic acid, water, iodomethane, etc.) enters the light component removal tower (0.1 MPa, 138 °C) for further separation, while the liquid phase (acetic acid, water, catalyst, etc.) is returned to the reactor to continue participating in the reaction; the upper part of the light component removal tower removes light components such as iodomethane and CO, and the side stream of the tower yields crude acetic acid (…). Acetic acid and water enter the dehydration tower (0.2 MPa, 157 °C), and the bottom of the tower (acetic acid, catalyst, etc.) is returned to the reactor through the evaporator. Acetic acid and water are separated from the upper part of the dehydration tower (which can be returned to the reactor through pipelines), while the acetic acid (containing trace impurities such as propionic acid) in the lower part enters the product tower (0.12 MPa, 146 °C) for further removal. Acetic acid (containing trace light components) collected from the upper part of the product tower is returned to the dehydration tower for separation, and the product acetic acid (>99.9 wt.%) is collected from the tower body and used to preheat the raw material methanol. The bottom liquid of the tower enters the stripping tower (to further separate acetic acid and propionic acid). The high-pressure absorption tower and the low-pressure absorption tower are used for tail gas absorption and recovery of iodomethane, which is returned to the reaction system.

[0044] Testing revealed that the system in this embodiment requires 1.7 kcal of heat for heating the reboiler of the light component removal tower, 7.62 kcal for the reboiler of the dehydration tower, 7.38 kcal for the reboiler of the finished product tower, and 0.01 kcal for the reboiler of the stripping tower, totaling 16.7 kcal. The waste heat boiler recovers residual heat to generate steam at ~175℃ (0.9 MPa), yielding 9.98 kcal of heat. Therefore, by utilizing this heat in the various reboilers, this solution can reduce energy loss by approximately 59.72% and save about 60% of the steam consumption of the original equipment, thereby significantly reducing production costs.

[0045] 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. A low-energy acetic acid production system, characterized in that, include: A reaction unit and a product distillation unit; the reaction unit includes a raw material methanol conveying pipeline, a carbon monoxide pipeline, and a reactor; the carbon monoxide pipeline is connected to the reactor; A portion of the crude product collected from the side outlet of the reactor is returned to the top of the reactor after absorbing waste heat in the waste heat boiler, while the other portion is processed by the product distillation unit and output through the product pipeline; the steam pipeline of the waste heat boiler provides a heat source for the reboiler in the product distillation unit after exchanging heat with the crude product of the reactor. The raw material methanol delivery pipeline is thermally coupled to the product pipeline through a methanol feed heat exchanger. The methanol in the raw material methanol delivery pipeline exchanges heat with the product in the product pipeline before being fed into the reactor.

2. The system according to claim 1, characterized in that, The product distillation unit includes a product column; the side outlet of the product column is connected to the product pipeline; the reboiler in the product distillation unit includes a product reboiler; the inlet of the product reboiler is connected to the bottom of the product column, and the outlet is connected to the side wall of the product column; the steam pipeline of the waste heat boiler is connected to the product reboiler as a reboiling heat source.

3. The system according to claim 2, characterized in that, The product distillation unit further includes an evaporator, a light-light product removal tower, and a dehydration tower connected in sequence. The crude product collected from the reactor side stream is processed sequentially through the evaporator, the light-light product removal tower, the dehydration tower, and the product tower before being output through the product pipeline. The reboiler in the product distillation unit further includes an evaporation reboiler, a light-weight reboiler, and a dehydration reboiler; the evaporation reboiler is located in the bottom of the evaporator; the inlet of the light-weight reboiler is connected to the bottom of the light-weight removal column, and the outlet is connected to the side wall of the light-weight removal column; the inlet of the dehydration reboiler is connected to the bottom of the dehydration column, and the outlet is connected to the side wall of the dehydration column; the steam pipeline of the waste heat boiler is connected to the evaporation reboiler, the light-weight reboiler, and the dehydration reboiler respectively to serve as a reboiling heat source.

4. The system according to claim 2, characterized in that, The product distillation unit further includes a stripping column; 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. The reboiler in the product distillation unit also includes a stripping reboiler; 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 of the waste heat boiler is connected to the stripping reboiler.

5. The system according to claim 3, characterized in that, It also includes a recovery unit, wherein the tail gas outlet at the top of the reactor and the tail gas outlet at the top of the light product removal tower are both connected to the recovery unit; the steam pipeline of the waste heat boiler provides a heat source for the reboiler in the recovery unit after exchanging heat with the crude product of the reactor.

6. The system according to claim 5, characterized in that, The recovery unit includes a high-pressure absorption tower and a methanol absorption storage tank; 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 the high-pressure absorption tower, and the bottom outlet of the high-pressure absorption tower is connected to the 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.

7. The system according to claim 6, characterized in that, The recovery unit also includes a regeneration tower; the bottom outlet of the methanol absorption storage tank is connected to the regeneration tower, and the bottom outlet of the regeneration tower is connected to a methanol lean solution tank; The reboiler in the recovery unit includes a regenerating reboiler, the inlet of which is connected to the bottom of the regeneration tower and the outlet of which is connected to the side wall of the regeneration tower.

8. The system according to claim 6, characterized in that, The recovery unit further includes a low-pressure absorption tower; 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.

9. The system according to claim 8, 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.

10. The system according to claim 3, characterized in that, The exhaust gas outlet at the top of the dehydration tower is connected to a dehydration cooler, the outlet of the dehydration cooler is connected to a dehydration reflux trough, and the bottom outlet of the dehydration reflux trough is connected to the dehydration tower.

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