An energy-saving three-tower distillation unit for crude methanol
By employing a thermal coupling process involving pre-distillation column, negative pressure distillation column, and pressurized distillation column, and optimizing the heat exchange network, the problem of heat waste in traditional methanol distillation is solved, achieving efficient methanol purification and reduced energy consumption, making it suitable for methanol production in the chemical industry.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- TIANJIN CARBON IND TECH CO LTD
- Filing Date
- 2025-06-12
- Publication Date
- 2026-07-17
AI Technical Summary
In traditional methanol distillation processes, the use of circulating water for cooling at the top of the atmospheric distillation tower and the pre-distillation tower leads to heat waste and high steam consumption. Furthermore, in existing three-tower processes, the heat at the top of the pre-distillation tower is not fully utilized, and the number of heat pumps is limited by safety and fire protection requirements, which cannot meet the requirements of new construction or renovation projects.
The process employs a thermal coupling of a pre-distillation column, a negative pressure distillation column, and a pressurized distillation column. The pressurized distillation column achieves a first effect, while the negative pressure distillation column achieves a second effect through its own heat pump. The heat is matched using methanol vapor at the top of the column, and the compressor is used to increase the pressure and temperature, thereby optimizing the heat exchange network and making full use of the heat.
It reduces steam consumption per ton of methanol to 0.32-0.42 tons and heat pump power consumption to 28-35 kWh, saving more than 40% energy compared to traditional processes, significantly reducing carbon emissions and operating costs.
Smart Images
Figure CN224506295U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of chemical equipment technology, specifically to an energy-saving three-tower distillation device for crude methanol. Background Technology
[0002] Methanol is an important chemical raw material, widely used in chemical, energy and fuel cell industries. In the production of methanol, distillation is a key separation operation used to purify methanol products. Traditional methanol distillation usually adopts a three-tower process: a pre-tower, a pressurized tower and an atmospheric tower. The steam from the top of the pressurized tower is used to heat the atmospheric tower to achieve energy saving. However, the atmospheric tower and the top of the pre-tower are cooled by circulating water, which leads to a large amount of heat being wasted, resulting in a high steam consumption of the entire system, approximately 1.2t steam / t refined methanol.
[0003] With the development of technology, in order to reduce energy consumption, most processes use four-tower, five-tower, or six-tower equipment configurations, which involve a large number of towers and occupy a large area. At the same time, in process scenarios using heat pumps, the large number of heat pumps can also be limited by safety and fire protection conditions, making it impossible to meet the requirements of actual new construction or technical renovation projects. There is still room for improvement in specific application scenarios.
[0004] However, in new projects, due to site constraints and investment limitations, a process route with fewer tower units is often preferred. After searching, the applicant has found the closest existing technology as follows:
[0005] Application number 202321742454.7 discloses a crude methanol three-tower triple-effect heat pump refining process device, which was also developed by our company. This patent discloses a technical solution comprising a pre-distillation tower, a negative pressure distillation tower, and a pressurized distillation tower connected in sequence. The lower parts of each tower are respectively connected to a pre-distillation tower reboiler, a negative pressure distillation tower reboiler, and a pressurized distillation tower reboiler. The vapor phase at the top of the pressurized distillation tower is used to heat the pre-distillation tower reboiler. The vapor phase at the top of the negative pressure distillation column is used to heat the reboiler of the negative pressure distillation column; refined methanol is collected from the top of the negative pressure distillation column and the pressurized distillation column; this application adopts a three-tower three-effect process, including three main equipment towers: a pre-distillation column, a negative pressure distillation column, and a pressurized distillation column. The third effect is achieved by the pressurized distillation column itself, the second effect is achieved by the methanol vapor at the top of the column being thermally coupled with the reboiler of the pre-distillation column, and the third effect is achieved by the heat matching of the negative pressure distillation column itself through its heat pump; this can transform traditional processes and achieve a significant reduction in energy consumption.
[0006] The above-mentioned applications can achieve a significant reduction in energy consumption and occupy a small space. However, the heat at the top of the pre-distillation column is not utilized, and the heat at the top of the pressurized distillation column is not fully utilized either. Therefore, a new technical solution is needed to solve the above-mentioned technical problems. Utility Model Content
[0007] This application provides an energy-saving device for three-tower distillation of crude methanol, comprising a pre-distillation tower, a negative pressure distillation tower, and a pressurized distillation tower connected in sequence. The lower part of the pre-distillation tower is equipped with a pre-tower start-up reboiler and a pre-tower reboiler. The lower part of the negative pressure distillation tower is equipped with a first negative pressure reboiler, a second negative pressure reboiler, a third negative pressure reboiler, and a start-up negative pressure reboiler. The lower part of the pressurized distillation tower is equipped with a pressurized reboiler. The top of the pre-distillation tower is connected to the second negative pressure reboiler via a pre-tower top pipeline. The top of the negative pressure distillation tower is connected to the third negative pressure reboiler via a negative pressure tower top pipeline. A compressor is installed on the negative pressure tower top pipeline. The top of the pressurized distillation tower is connected to the pre-tower reboiler and the first negative pressure reboiler via a pressurized tower top pipeline.
[0008] As a preferred embodiment, the output end of the second negative pressure tower reboiler is connected to the light component impurity extraction device via the output pipeline of the second negative pressure tower reboiler.
[0009] As a preferred embodiment, the light component impurity extraction device includes a pre-extraction tank connected to the second output pipeline of the reboiler of the negative pressure tower. A condensation device is installed on the second output pipeline of the reboiler of the negative pressure tower. An extraction water pipeline is connected to one side of the pre-extraction tank. A non-condensable gas pipeline is installed at the top of the pre-extraction tank. The bottom of the pre-extraction tank is connected to a pre-recirculation tank via a bottom pipeline of the pre-extraction tank. The bottom of the pre-recirculation tank is connected to a pre-distillation tower via a pre-circulation pipeline. A pre-circulation pump is installed on the pre-circulation pipeline.
[0010] As a preferred embodiment, the condensation device includes a pre-tower primary condenser and a pre-tower secondary condenser connected in sequence.
[0011] A pre-distillation column feed line is provided on one side of the pre-distillation column, and a crude alcohol feed preheater is provided on the pre-distillation column feed line.
[0012] As a preferred embodiment, the output end of the third reboiler of the negative pressure tower is connected to the methanol extraction device of the negative pressure tower through the output pipeline of the third reboiler of the negative pressure tower; the top of the negative pressure distillation tower is directly connected to the methanol extraction device of the negative pressure tower through the top pipeline of the negative pressure tower.
[0013] As a preferred embodiment, the methanol extraction device for the negative pressure tower includes a negative pressure tower reflux tank connected to the three-output pipeline of the negative pressure tower reboiler. A negative pressure tower top cooler is installed on the three-output pipeline of the negative pressure tower reboiler. A vacuum pump is connected to the top of the negative pressure tower reflux tank, and a negative pressure tower reflux pipeline is connected to the bottom of the negative pressure tower reflux tank. The negative pressure tower reflux pipeline is connected to a negative pressure distillation tower, and the negative pressure tower reflux pipeline is also connected to a methanol extraction pipeline from the negative pressure tower.
[0014] As a preferred embodiment, the methanol extraction pipeline from the negative pressure tower is connected to the methanol tank.
[0015] As a preferred embodiment, the output end of the negative pressure tower reboiler is connected to the pressurized tower refined methanol collection device via the negative pressure tower reboiler output pipeline, and the output end of the pre-tower reboiler is connected to the pressurized tower refined methanol collection device via the pre-tower reboiler output pipeline.
[0016] As a preferred embodiment, the pressurized tower methanol extraction device includes a pressurized tower reflux tank connected to the output pipeline of the negative pressure tower reboiler and the output pipeline of the pre-tower reboiler. The bottom of the pressurized tower reflux tank is connected to the pressurized distillation tower through the pressurized tower reflux pipeline, and the pressurized tower reflux pipeline is connected to the pressurized tower methanol extraction pipeline.
[0017] As a preferred embodiment, a pressurized methanol cooler is installed on the pressurized methanol collection pipeline.
[0018] As a preferred embodiment, the pressurized tower methanol extraction pipeline is connected to the methanol tank.
[0019] As a preferred embodiment, the bottom of the negative pressure distillation column is connected to the pressurized distillation column via a negative pressure column bottom pipeline, and a pressurized column feed preheater is installed on the negative pressure column bottom pipeline.
[0020] As a preferred embodiment, a fusel oil collection pipeline is provided on one side of the pressurized distillation column, and a wastewater collection pipeline is provided in the bottom of the pressurized distillation column. A wastewater collection pump and a wastewater cooler are provided on the wastewater collection pipeline.
[0021] As a preferred embodiment, the wastewater extraction pipeline is connected to the input and output ends of the pressurized tower feed preheater.
[0022] In this application, the top steam of the pressurized distillation column heats the pre-distillation column reboiler and the first negative pressure column reboiler; the methanol steam at the top of the pre-distillation column heats the second negative pressure column reboiler; and the top steam of the negative pressure column, after being pressurized and heated by a compressor, heats the third negative pressure column reboiler. Through this application, the unit consumption of the methanol distillation process can be reduced from 1.2t steam / t refined methanol to 0.32-0.42t steam / t refined methanol, and the heat pump power consumption per ton of methanol is reduced to 28-35kw.h. Compared with the traditional dual-tower thermal coupling process, it can save more than 40% of energy, significantly reducing the operating costs of enterprises, significantly reducing carbon emissions, and improving enterprise competitiveness. Attached Figure Description
[0023] Figure 1 This is a connection diagram of this application;
[0024] Figure Labels
[0025] 1. Pre-distillation column; 2. Negative pressure distillation column; 3. Pressurized distillation column; 4. Pre-column feed line; 5. Crude alcohol feed preheater; 6. Pre-column reboiler line; 7. Pre-column reboiler pump; 8. Negative pressure column reboiler line; 9. Negative pressure column reboiler pump; 10. Pressurized column feed preheater; 11. Fusel alcohol collection line; 12. Wastewater collection line; 13. Wastewater collection pump; 14. Wastewater cooler; 15. Pre-column start-up reboiler; 16. Pre- 17. Reboiler for the negative pressure tower; 18. Reboiler for the negative pressure tower; 19. Reboiler for the negative pressure tower; 20. Reboiler for the negative pressure tower start-up; 21. Reboiler for the pressurized tower; 22. Pre-tower top pipeline; 23. Reboiler for the negative pressure tower; 24. Compressor; 25. Top pipeline of the pressurized tower; 26. Steam pipeline; 27. Steam condensate pipeline; 28. Output pipeline of reboiler for the negative pressure tower; 29. Pre-tower extraction tank; 30. 31. Pre-tower primary condenser; 32. Pre-tower secondary condenser; 33. Extraction water pipeline; 34. Non-condensable gas pipeline; 35. Bottom pipeline of pre-tower extraction tank; 36. Pre-tower reflux tank; 37. Pre-tower circulation pipeline; 38. Pre-tower circulation pump; 39. Three-output pipeline of negative pressure tower reboiler; 40. Negative pressure tower reflux tank; 41. Negative pressure tower top condenser; 42. Negative pressure tower top cooler; 43. Vacuum pump equipment; 44. Negative pressure tower return... 44. Reflux pump of negative pressure tower; 45. Refined methanol collection pipeline of negative pressure tower; 46. Refined methanol cooler of negative pressure tower; 47. Refined methanol tank; 48. Output pipeline of reboiler of negative pressure tower; 49. Output pipeline of reboiler of pre-tower; 50. Reflux tank of pressurized tower; 51. Reflux pipeline of pressurized tower; 52. Reflux pump of pressurized tower; 53. Refined methanol collection pipeline of pressurized tower; 54. Refined methanol cooler of pressurized tower; 55. Fusel cooler. Detailed Implementation
[0026] The following is in conjunction with the appendix Figure 1 The specific embodiments of this utility model will be described in detail below. It should be noted that the specific embodiments described herein are only for illustration and explanation of this utility model and are not intended to limit this utility model.
[0027] Example 1:
[0028] This embodiment provides an energy-saving three-tower distillation device for crude methanol, comprising a pre-distillation tower 1, a negative pressure distillation tower 2, and a pressurized distillation tower 3 connected in sequence. A pre-distillation tower 1 has a pre-tower feed line 4 on one side, and a crude methanol feed preheater 5 is installed on the pre-tower feed line 4. The bottom of the pre-distillation tower 1 is connected to the negative pressure distillation tower 2 via a pre-tower reboiler line 6, and a pre-tower reboiler pump 7 is installed on the pre-tower reboiler line 6. The reboiler of the negative pressure distillation tower 2 is connected to the pressurized distillation tower 3 via a negative pressure reboiler line 8, and a negative pressure reboiler pump 9 and a pressurized distillation tower feed line 3 are installed sequentially on the negative pressure reboiler line 8. The pressurized distillation column 3 includes a feed preheater 10; a fusel oil collection pipeline 11 is provided on one side of the pressurized distillation column 3 for collecting fusel oil, and a fusel oil cooler 55 is provided on the fusel oil collection pipeline 11; a wastewater collection pipeline 12 is provided in the bottom of the pressurized distillation column 3 for collecting wastewater, and a wastewater collection pump 13 and a wastewater cooler 14 are provided on the wastewater collection pipeline 12; preferably, the wastewater collection pipeline 12 is connected to the input and output ends of the pressurized column feed preheater 10, that is, the wastewater collection pipeline 12 passes through the pressurized column feed preheater 10, and the heat of the wastewater provides heat to the pressurized column feed preheater 10.
[0029] The lower part of the pre-distillation column 1 is equipped with a pre-column start-up reboiler 15 and a pre-column reboiler 16. The lower part of the negative pressure distillation column 2 is equipped with a negative pressure column reboiler one 17, a negative pressure column reboiler two 18, a negative pressure column reboiler three 19, and a negative pressure column start-up reboiler 20. The lower part of the pressurized distillation column 3 is equipped with a pressurized column reboiler 21. The top of the pre-distillation column 1 is connected to the negative pressure column reboiler two 18 via a pre-column top pipeline 22, meaning that the gas phase collected from the top of the pre-distillation column 1 is used to heat the negative pressure column reboiler two 18. The top of the negative pressure distillation column 2 is connected to the negative pressure column reboiler three 19 via a negative pressure column top pipeline 23. A compressor 24 is installed on the negative pressure column top pipeline 23, and the gas phase collected from the top of the negative pressure distillation column 2 is compressed to heat the negative pressure column reboiler three 19. The top of column 3 is connected to the pre-column reboiler 16 and the negative pressure column reboiler 17 via the pressurized column top pipeline 25. The gas phase collected from the top of the pressurized distillation column 3 is used to heat the pre-column reboiler 16 and the negative pressure column reboiler 17. The input ends of the pressurized column reboiler 21, the pre-column start-up reboiler 15, and the negative pressure column start-up reboiler 20 are respectively connected to the steam pipeline 26, through which 0.5 MPa A steam is introduced to heat the pressurized column reboiler 21, the pre-column start-up reboiler 15, and the negative pressure column start-up reboiler 20. The output ends of the pressurized column reboiler 21, the pre-column start-up reboiler 15, and the negative pressure column start-up reboiler 20 are respectively connected to the steam condensate pipeline 27. Preferably, the steam condensate pipeline 27 passes through the crude alcohol feed preheater 5 to provide heat to the crude alcohol feed preheater 5. Alternatively, the pressurized tower reboiler 21, the pre-tower start-up reboiler 15, and the negative pressure tower start-up reboiler 20 can also be heated by heat sources from other distillation systems to achieve thermal coupling.
[0030] As a preferred embodiment, the top pressure of the pre-distillation column 1 is 120-180 kPa, the top pressure of the negative pressure distillation column 2 is 35-70 kPa, and the top pressure of the pressurized distillation column 3 is 280-480 kPa.
[0031] Example 2:
[0032] This embodiment describes the device for removing light component impurities at the top of the pre-distillation column 1, specifically:
[0033] The output end of the second reboiler 18 of the negative pressure tower is connected to the light component impurity collection device through the output pipeline 28 of the second reboiler 18 of the negative pressure tower. The light component impurity collection device includes a pre-tower extraction tank 29 connected to the output pipeline 28 of the second reboiler 18 of the negative pressure tower. A condensation device is provided on the output pipeline 28 of the second reboiler 18 of the negative pressure tower. Preferably, the condensation device adopts a first-stage condenser 30 and a second-stage condenser 31 of the pre-tower connected in sequence. An extraction water pipeline 32 is connected to one side of the pre-tower extraction tank 29. Extraction water is introduced into the pre-tower extraction tank 29 through the extraction water pipeline 32. A non-condensable gas pipeline 33 is provided at the top of the pre-tower extraction tank 29. As is well known, a regulating valve is provided on the non-condensable gas pipeline 33 to control the stability of the pressure of the pre-distillation tower 1.
[0034] The bottom of the pre-extraction tank 29 is connected to the pre-recirculation tank 35 via the bottom pipeline 34 of the pre-extraction tank. The bottom of the pre-recirculation tank 35 is connected to the pre-distillation column 1 via the pre-recirculation pipeline 36. A pre-recirculation pump 37 is installed on the pre-recirculation pipeline 36. The light component impurity collection device collects the light phase component and refluxes part of the liquid through the pre-extraction tank 29 and the pre-recirculation tank 35 to further recover the methanol entrained in the light phase and improve the methanol recovery rate of the system.
[0035] Example 3:
[0036] The top of the negative pressure distillation column 2 yields refined methanol, which will be described in detail in this embodiment:
[0037] The output end of the reboiler 319 in the negative pressure column is connected to the methanol collection device of the negative pressure column via the reboiler 319 output pipeline 38. The methanol collection device of the negative pressure column includes a reflux tank 39 connected to the reboiler 319 output pipeline 38. The top of the negative pressure distillation column 2 is connected to the reflux tank 39 via a top pipeline 23. A top condenser 40 is installed on the top pipeline 23. A top cooler 41 is installed on the reboiler 31 output pipeline 38. The top of the reflux tank 39... The unit is connected to a vacuum pump device 42. The bottom of the negative pressure tower reflux tank 39 is connected to a negative pressure tower reflux pipeline 43. A negative pressure tower reflux pump 44 is installed on the negative pressure tower reflux pipeline 43. The negative pressure tower reflux pipeline 43 is connected to the negative pressure distillation column 2. The negative pressure tower reflux pipeline 43 is also connected to a negative pressure tower refined methanol collection pipeline 45. A negative pressure tower refined methanol cooler 46 is installed on the negative pressure tower refined methanol collection pipeline 45. Preferably, the negative pressure tower refined methanol collection pipeline 45 is connected to a refined methanol tank 47, which stores refined methanol.
[0038] The feed from the bottom of the pre-distillation column 1 is pumped by the pre-distillation column bottom pump 7 to the negative pressure distillation column 2 for methanol distillation. The refined methanol vapor collected from the top of the negative pressure distillation column 2 is compressed by the compressor 24 and then sent to the negative pressure column reboiler 18 for heat exchange and condensation before being collected to the negative pressure column reflux tank 39. Part of the liquid phase in the negative pressure column reflux tank 39 is returned to the negative pressure distillation column 2 through the negative pressure column reflux pump 44 and the negative pressure column reflux pipeline 43, and part is sent to the refined methanol tank 47. The feed from the bottom of the negative pressure distillation column 2 is preheated by the pressurized column feed preheater 10 and then sent to the pressurized distillation column 3.
[0039] Example 4:
[0040] The top of pressurized distillation column 3 yields refined methanol, which will be described in detail in this embodiment:
[0041] The output end of the reboiler 17 of the negative pressure tower is connected to the methanol extraction device of the pressurized tower via the reboiler output pipeline 48 of the negative pressure tower. The output end of the pre-reboiler 16 is connected to the methanol extraction device of the pressurized tower via the pre-reboiler output pipeline 49. The methanol extraction device of the pressurized tower includes a pressurized tower reflux tank 50 connected to the reboiler output pipeline 48 and the pre-reboiler output pipeline 49 of the negative pressure tower. The bottom of the pressurized tower reflux tank 50 is connected to the pressurized distillation tower 3 via the pressurized tower reflux pipeline 51. A pressurized tower reflux pump 52 is installed on the pressurized tower reflux pipeline 51. The pressurized tower reflux pipeline 51 is connected to the methanol extraction pipeline 53 of the pressurized tower. A methanol cooler 54 of the pressurized tower is installed on the methanol extraction pipeline 53 of the pressurized tower. Preferably, the methanol extraction pipeline 53 of the pressurized tower is connected to a methanol tank 47, which stores methanol.
[0042] The refined methanol collected from the top of the pressurized distillation column 3 is transported to the pre-column reboiler 16 and the negative pressure column reboiler 17 for heat exchange. The material after heat exchange is transported to the pressurized column reflux tank 50. The refined methanol in the pressurized column reflux tank 50 is partially returned to the pressurized distillation column 3 through the pressurized column reflux pipeline 51 via the pressurized column reflux pump 52, and part of it is transported to the refined methanol tank 47 for refined methanol recovery.
[0043] Example 5:
[0044] This embodiment provides a specific application scenario:
[0045] This application provides a specific application scenario, specifically:
[0046] At a methanol plant, a new crude methanol refining and recovery unit with an annual output of 500,000 tons was installed. The feed rate was 74,696.1 kg / h. When the process parameters were optimized to the best, the steam energy consumption for refined methanol was about 0.4 tons of steam / refined methanol, with the methanol purity reaching over 99.99% and the ethanol content less than 100 ppm.
[0047] In this embodiment, the methanol content is 96%, the water content is 3%, and the ethanol content is approximately 500 ppm. The crude methanol is preheated to 70°C by the crude alcohol feed preheater 5 before entering the pre-distillation column 1. The operating parameters of each column are shown in the table below:
[0048]
[0049]
[0050] The process flow of this embodiment is as follows:
[0051] The crude methanol from the synthesis section first exchanges heat with the low-pressure saturated steam condensate, and then enters the pre-distillation column 1. The top steam of the pre-distillation column 1 goes to the reboiler 2 18 of the negative pressure column for heat exchange, and then goes to the first-stage condenser 30 of the pre-distillation column. Most of the steam is condensed, and the condensed liquid phase enters the pre-distillation column reflux tank 35, while the gas phase enters the second-stage condenser 31 of the pre-distillation column. The condensed liquid phase enters the pre-distillation column extraction tank 29, and extraction water is simultaneously introduced into the pre-distillation column extraction tank 29. The liquid phase of the pre-distillation column extraction tank 29 returns to the pre-distillation column reflux tank 35, and the non-condensable vapor goes to the tail gas emission system. The pre-distillation column start-up reboiler 15 uses steam as a heat source.
[0052] The material from the bottom of the pre-distillation column 1 is fed into the lower part of the negative pressure distillation column 2 by the pre-distillation column bottom pump 7. The methanol vapor at the top of the negative pressure distillation column 2 is split into two streams. One part of the methanol vapor is sent to the compressor 24, where it is compressed and heated before entering the negative pressure column reboiler 19 for heat exchange. The condensed methanol vapor then passes through the negative pressure column top cooler 41 and returns to the negative pressure column reflux tank 39. The other part of the methanol vapor directly enters the negative pressure column top condenser 40 for condensation and then returns to the negative pressure column reflux tank 39. Part of the refined methanol in the negative pressure column reflux tank 39 is returned to the negative pressure distillation column 2, and part is collected as refined methanol. The collected stream enters the negative pressure column refined methanol cooler 46, and the cooled refined methanol is sent to the boundary area to the refined methanol tank 47 for storage. The negative pressure column start-up reboiler 20 uses steam as a heat source.
[0053] The bottom liquid of negative pressure distillation column 2, after being preheated by the pressurized column feed preheater 10, is sent to the lower part of pressurized distillation column 3 by negative pressure column bottom pump 9. Methanol vapor from the top of pressurized distillation column 3 is split into two streams: one is sent to the pre-column reboiler 16, and the other to the negative pressure column reboiler 17. The condensed methanol after heat exchange enters the pressurized column reflux tank 50. A portion of the liquid phase in the reflux tank 50 is returned to the pressurized column reboiler 21, while a portion is collected and sent to the pressurized column refined methanol cooler. Cooler 54 cools the refined methanol and sends it to the refined methanol tank 47 for storage. The fusel oil is collected from the fusel oil collection pipeline 11 of the pressurized distillation column 3. After being cooled by fusel oil cooler 55, the fusel oil enters the fusel oil intermediate tank. The wastewater collected from the bottom of the pressurized distillation column 3 is first preheated for the feed of the pressurized distillation column, and then cooled by wastewater cooler 14 before being sent to the wastewater treatment device. The reboiler 21 of the pressurized column uses low-pressure saturated steam as a heat source.
[0054] In this embodiment, the pressurized reboiler 21 uses a steam heat source. The methanol vapor at the top of the pressurized distillation column 3 provides heat to the negative pressure column reboiler 17 and the pre-coiler 16. The vapor at the top of the negative pressure distillation column 2 provides heat to its own negative pressure column reboiler 19 through the compressor 24. The methanol vapor at the top of the pre-coilation column 1 provides heat to the negative pressure column reboiler 18. The energy consumption for each ton of refined methanol is about 0.4t of steam.
[0055] Through the above solutions, steam consumption in this case is reduced by 50%-70%. For the transformation of traditional three-tower markets, the investment is small and the operation is highly feasible. By adopting energy-saving measures such as heat exchange network optimization, heat recovery, and thermal distillation, steam consumption is greatly reduced, and the consumption per ton of methanol can be reduced to 0.4 tons of steam / ton of refined methanol.
[0056] In summary, by adopting the above technical solutions, this embodiment employs a thermal coupling process of a pre-distillation tower, a negative pressure distillation tower, and a pressurized distillation tower, along with a heat pump process for the negative pressure tower itself. This optimizes the heat exchange network, enhances energy-saving potential, and enables the extraction of methanol with a concentration >99.99% and an ethanol content ≤100ppm. Furthermore, compared to traditional methanol processes, it can reduce steam consumption to 0.4t steam / t refined alcohol, achieving a significant reduction in energy consumption.
[0057] The preferred embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.
[0058] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, the various possible combinations in this application will not be described separately.
[0059] Furthermore, various different implementations of this application can be combined in any way, as long as they do not violate the spirit of this application, and such combinations should also be regarded as the content disclosed in this application.
Claims
1. A crude methanol three-column energy-saving rectification device, comprising a pre-rectification column (1), a negative pressure rectification column (2), and a pressurized rectification column (3) connected in sequence, characterized in that, The lower part of the pre-distillation column (1) is provided with a pre-column start-up reboiler (15) and a pre-column reboiler (16). The lower part of the negative pressure distillation column (2) is provided with a negative pressure column reboiler one (17), a negative pressure column reboiler two (18), a negative pressure column reboiler three (19), and a negative pressure column start-up reboiler (20). The lower part of the pressurized distillation column (3) is provided with a pressurized column reboiler (21). The top of the pre-distillation column (1) The top of the pre-column top pipeline (22) is connected to the second reboiler of the negative pressure column (18). The top of the negative pressure distillation column (2) is connected to the third reboiler of the negative pressure column (19) via the top pipeline (23). A compressor (24) is installed on the top pipeline (23). The top of the pressurized distillation column (3) is connected to the pre-column reboiler (16) and the first reboiler of the negative pressure column (17) via the top pipeline (25).
2. The energy saving apparatus for crude methanol three-column rectification according to claim 1, characterized in that, The output end of the negative pressure tower reboiler two (18) is connected to the light component impurity extraction device through the negative pressure tower reboiler two output pipeline (28).
3. The energy-saving device for three-tower distillation of crude methanol according to claim 1, characterized in that, A pre-distillation column (1) is provided with a pre-column feed line (4) on one side, and a crude alcohol feed preheater (5) is provided on the pre-column feed line (4).
4. The energy saving device for crude methanol three-column rectification according to claim 1, characterized in that, The output end of the reboiler three (19) of the negative pressure tower is connected to the methanol extraction device of the negative pressure tower through the output pipeline (38) of the reboiler three of the negative pressure tower; the top of the negative pressure distillation tower (2) is directly connected to the methanol extraction device of the negative pressure tower through the tower top pipeline (23).
5. The energy saving device for crude methanol three-column rectification according to claim 4, characterized in that, The negative pressure tower methanol extraction device includes a negative pressure tower reflux tank (39) connected to the three output lines (38) of the negative pressure tower reboiler. A negative pressure tower top cooler (41) is installed on the three output lines (38) of the negative pressure tower reboiler. A vacuum pump device (42) is connected to the top of the negative pressure tower reflux tank (39). A negative pressure tower reflux line (43) is connected to the bottom of the negative pressure tower reflux tank (39). The negative pressure tower reflux line (43) is connected to the negative pressure distillation tower (2). The negative pressure tower reflux line (43) is also connected to a negative pressure tower methanol extraction line (45).
6. The energy saving device for crude methanol three-column rectification according to claim 1, characterized in that, The output end of the negative pressure tower reboiler (17) is connected to the pressurized tower refined methanol extraction device through the negative pressure tower reboiler output pipeline (48), and the output end of the pre-tower reboiler (16) is connected to the pressurized tower refined methanol extraction device through the pre-tower reboiler output pipeline (49).
7. The energy-saving device for three-tower distillation of crude methanol according to claim 6, characterized in that, The pressurized tower methanol extraction device includes a pressurized tower reflux tank (50) connected to the output pipeline (48) of the negative pressure tower reboiler and the output pipeline (49) of the pre-tower reboiler. The bottom of the pressurized tower reflux tank (50) is connected to the pressurized distillation tower (3) through the pressurized tower reflux pipeline (51), and the pressurized tower reflux pipeline (51) is connected to the pressurized tower methanol extraction pipeline (53).
8. The energy saving device for crude methanol three-column rectification according to claim 1, characterized in that, The bottom of the negative pressure distillation column (2) is connected to the pressurized distillation column (3) through the negative pressure column bottom pipeline (8), and the pressurized column feed preheater (10) is installed on the negative pressure column bottom pipeline (8).
9. The energy saving device for crude methanol three-column rectification according to claim 8, characterized in that, A fusel oil collection pipeline (11) is provided on one side of the pressurized distillation column (3), and a wastewater collection pipeline (12) is provided in the bottom of the pressurized distillation column (3). A wastewater collection pump (13) and a wastewater cooler (14) are provided on the wastewater collection pipeline (12).
10. The energy saving device for crude methanol three-column rectification according to claim 9, characterized in that, The wastewater extraction pipeline (12) is connected to the input and output ends of the pressurized tower feed preheater (10).