Crude methanol refining device

Abstract

The utility model provides a crude methanol refining device which comprises a pre-rectifying tower, the pre-rectifying tower is respectively connected with a side line tower and a pressurizing tower, the pressurizing tower is connected with an atmospheric tower, and a pre-tower reboiler, a side line tower reboiler, a pressurizing tower reboiler and an atmospheric tower reboiler are respectively arranged on the pre-rectifying tower, the side line tower, the pressurizing tower and the atmospheric tower. The gas phase extracted from the top of the atmospheric tower exchanges heat with the pre-tower reboiler and the side tower reboiler; gas extracted from the top of the pressurizing tower exchanges heat with a reboiler of the atmospheric tower; the thermal coupling technology of the pre-rectifying tower, the side tower, the pressurizing tower and the atmospheric tower is adopted, a heat exchange network is optimized, the energy-saving space is improved, methanol with the concentration larger than 99.99% can be extracted, and the content of ethanol is 10-200 ppm; according to the method, the original devices such as a pre-rectifying tower, a pressurizing tower and an atmospheric tower are improved, the improvement cost is low, and compared with the traditional methanol process, the unit consumption of steam can be reduced to 0.7-0.8 t steam / t refined alcohol, so that the energy consumption is greatly reduced.

Description

Technical Field

[0001] This application relates to the field of chemical technology, specifically to a crude methanol refining apparatus. Background Technology

[0002] Methanol is an important chemical raw material, widely used in chemical, energy and fuel cell fields. In the production of methanol, distillation is a key separation operation used to purify methanol products. Traditional methanol distillation usually uses the thermal coupling technology of pressurized column and atmospheric column to achieve energy saving of the distillation system. However, the atmospheric column in the system still wastes a lot of heat, and the system energy consumption is still relatively high.

[0003] For example, traditional methanol distillation processes typically employ a three-tower system consisting of a pre-tower, a pressurized tower, and an atmospheric tower. The overhead steam from the pressurized tower is used to heat the atmospheric tower, achieving energy savings. However, a significant amount of heat remains after the atmospheric tower provides heat to the pre-tower, resulting in substantial heat waste and high steam consumption per ton of the entire system, approximately 1.2 t of steam per t of distilled methanol. Given the increasingly stringent national requirements for carbon emission standards, a new technology is needed to fully recover the heat from the atmospheric tower in the existing system to achieve energy conservation and emission reduction goals.

[0004] The applicant intends to achieve further energy conservation and emission reduction by setting up side-line towers and adjusting the heat utilization between each tower. However, no relevant patent applications were found through a search.

[0005] In summary, a new technical solution is needed to address the aforementioned technical problems. Utility Model Content

[0006] This application provides a crude methanol refining apparatus, including a pre-distillation column, which is connected to a side-stream column and a pressurized column, and the pressurized column is connected to an atmospheric column. The pre-distillation column, side-stream column, pressurized column, and atmospheric column are respectively equipped with a pre-column reboiler, a side-stream column reboiler, a pressurized column reboiler, and an atmospheric column reboiler. The gas drawn from the top of the atmospheric column exchanges heat with the pre-column reboiler and the side-stream column reboiler; the gas drawn from the top of the pressurized column exchanges heat with the atmospheric column reboiler.

[0007] As a preferred embodiment, the top of the atmospheric pressure tower is connected to the side-stream tower reboiler and the pre-tower reboiler via the atmospheric pressure tower outlet pipeline and the atmospheric pressure tower outlet pipeline, respectively.

[0008] As a preferred embodiment, the top of the pressurized tower is connected to the reboiler of the atmospheric tower via a top outlet pipeline.

[0009] As a preferred embodiment, the top of the pre-distillation column is provided with a pre-column top collection device.

[0010] As a preferred embodiment, the pre-distillation column top collection device includes a pre-distillation column top reflux tank connected to the top of the pre-distillation column. The bottom of the pre-distillation column top reflux tank is connected to the pre-distillation column via a pre-distillation column reflux line. The upper part of the pre-distillation column top reflux tank is connected to an extraction tank via a collection line. A condenser is installed on the collection line. A venting gas line is installed on the upper part of the extraction tank. An extraction water line is installed on one side of the extraction tank. The bottom of the extraction tank is connected to the pre-distillation column top reflux tank via an extraction tank collection line.

[0011] As a preferred embodiment, a feed line is provided on one side of the pre-distillation column, and a pre-column feed preheater is provided on the feed line.

[0012] As a preferred embodiment, the top of the side-stream tower is connected to the side-stream tower top reflux tank via a side-stream tower top outflow pipeline. A side-stream tower condenser is installed on the side-stream tower top outflow pipeline. The bottom of the side-stream tower top reflux tank is connected to the side-stream tower via a side-stream tower reflux pipeline. A side-stream tower reflux pump is installed on the side-stream tower reflux pipeline. The side-stream tower reflux pipeline is connected to the side-stream tower refined methanol outflow pipeline.

[0013] As a preferred embodiment, the methanol extraction pipeline from the side-stream tower is connected to the methanol tank.

[0014] As a preferred embodiment, the top of the pressurized tower is connected to the pressurized tower reflux tank via a first pressurized tower top outlet pipeline and a second pressurized tower top outlet pipeline. A pressurized tower condenser is installed on the second pressurized tower top outlet pipeline. The bottom of the pressurized tower reflux tank is connected to the pressurized tower via a pressurized tower reflux pipeline. A pressurized tower reflux pump is installed on the pressurized tower reflux pipeline. The pressurized tower reflux pipeline is connected to the pressurized tower refined methanol outlet pipeline.

[0015] As a preferred embodiment, the pressurized tower methanol extraction pipeline is connected to the methanol tank.

[0016] As a preferred embodiment, the atmospheric reboiler is connected to the pressurized tower reflux tank via the atmospheric reboiler output pipeline.

[0017] As a preferred embodiment, the top of the atmospheric pressure tower is connected to the atmospheric pressure tower reflux tank via an atmospheric pressure tower outlet pipeline and an atmospheric pressure tower outlet pipeline II. An atmospheric pressure tower condenser is installed on the atmospheric pressure tower outlet pipeline II. The bottom of the atmospheric pressure tower reflux tank is connected to the atmospheric pressure tower via an atmospheric pressure tower reflux pipeline. An atmospheric pressure tower reflux pump is installed on the atmospheric pressure tower reflux pipeline. The atmospheric pressure tower reflux pipeline is connected to the atmospheric pressure tower refined methanol outlet pipeline.

[0018] As a preferred embodiment, the methanol extraction pipeline from the atmospheric pressure tower is connected to the methanol tank.

[0019] As a preferred embodiment, the side-stream reboiler is connected to the atmospheric reflux tank via the side-stream reboiler output pipeline; the pre-stream reboiler is connected to the atmospheric reflux tank via the pre-stream reboiler output pipeline.

[0020] As a preferred embodiment, one side of the atmospheric pressure tower is connected to a fusel oil extraction pipeline, and a fusel oil condenser, a gas-liquid collection tank, and a fusel oil extraction pump are sequentially installed on the fusel oil extraction pipeline.

[0021] As a preferred embodiment, a wastewater extraction pipeline is installed at the bottom of the atmospheric pressure tower, and a wastewater extraction pump is installed on the wastewater extraction pipeline.

[0022] As a preferred embodiment, the input end of the pressurized reboiler is connected to the steam pipeline, and the output end of the pressurized reboiler is connected to the steam condensate collection pipeline.

[0023] As a preferred embodiment, the bottom of the pre-distillation column is also connected to a pre-column reboiler, the output end of which is connected to a steam pipeline and the output end of which is connected to a steam condensate collection pipeline.

[0024] This application employs a thermally coupled process involving a pre-distillation tower, a side-stream tower, a pressurized tower, and an atmospheric tower, optimizing the heat exchange network and increasing energy efficiency. It can produce methanol with a concentration >99.99% and an ethanol content of 10-200ppm. The process can be simplified by modifying existing pre-distillation tower, pressurized tower, and atmospheric tower equipment, resulting in low modification costs. Compared to traditional methanol processes, it can reduce steam consumption to 0.7-0.8t steam / t refined alcohol, achieving a significant reduction in energy consumption. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of this application;

[0026] 1. Pre-distillation column; 2. Side-stream column; 3. Pressurized column; 4. Atmospheric column; 5. Pre-column side-stream; 6. Pre-column reboiler outlet line; 7. Pre-column outlet pump; 8. Side-stream column side-stream; 9. Pressurized column reboiler outlet line; 10. Fusel alcohol outlet line; 11. Fusel alcohol condenser; 12. Gas-liquid collection tank; 13. Fusel alcohol outlet pump; 14. Wastewater outlet line; 15. Wastewater outlet pump; 16. Feed line; 17. Feed preheater; 18. 19. Pre-boiler; 20. Side-stream reboiler; 21. Pressurized tower reboiler; 22. Atmospheric tower reboiler; 23. Steam pipeline; 24. Steam condensate collection pipeline; 25. Atmospheric tower collection pipeline; 26. First collection pipeline of atmospheric tower; 27. First collection pipeline of pressurized tower top; 28. Pre-boiler reboiler; 29. ​​Pre-boiler reflux tank; 30. Pre-boiler reflux pump; 31. Collection pipeline; 32. Extraction... 33. Extraction tank; 34. Condenser; 35. Venting gas pipeline; 36. Extraction water pipeline; 37. Extraction tank outlet pipeline; 38. Side stream top outlet pipeline; 39. Side stream top reflux tank; 40. Side stream condenser; 41. Side stream reflux pipeline; 42. Side stream refined methanol outlet pipeline; 43. Refined methanol tank; 44. Pressurized tower reflux tank; 45. Pressurized tower condenser; 46. Pressurized tower top outlet pipeline Pipeline 2; 47. Pressurized Tower Reflux Pipeline; 48. Pressurized Tower Reflux Pump; 49. Pressurized Tower Refined Methanol Outlet Pipeline; 50. Atmospheric Tower Reboiler Outlet Pipeline; 51. Atmospheric Tower Outlet Pipeline 2; 52. Atmospheric Tower Reflux Tank; 53. Atmospheric Tower Condenser; 54. Atmospheric Tower Reflux Pipeline; 55. Atmospheric Tower Reflux Pump; 56. Atmospheric Tower Refined Methanol Outlet Pipeline; 57. Side Stream Tower Reboiler Outlet Pipeline; 58. Pre-Tower Reboiler Outlet Pipeline. Detailed Implementation

[0027] 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 for illustration and explanation only and are not intended to limit the scope of this utility model.

[0028] Example 1:

[0029] This embodiment provides a crude methanol refining apparatus, including a pre-distillation column 1, which is connected to a side-stream column 2 and a pressurized column 3. The pressurized column 3 is connected to an atmospheric column 4. The top pressure of the pre-distillation column 1 is 100-180 kPa, the top pressure of the side-stream column 2 is 50-95 kPa, the top pressure of the pressurized column 3 is 700-800 kPa, and the top pressure of the atmospheric column 4 is 150-200 kPa. More specifically, one side of the pre-distillation column 1 is connected to the side-stream column 2 via a pre-column side-stream 5, and the bottom of the pre-distillation column 1 is connected to the pressurized column 3 via a pre-column bottom-out pipeline 6. A pre-column bottom-out pump 7 is installed on the pre-column bottom-out pipeline 6. One side of column 2 is connected to column 1 via side line 8. Setting up side line column 2 on one side of column 1 can reduce energy consumption, improve product quality, and reduce investment costs. The bottom of column 3 is connected to column 4 via bottom outlet pipeline 9. One side of column 4 is connected to fusel oil outlet pipeline 10. Fusel oil outlet pipeline 10 is sequentially equipped with fusel oil condenser 11, gas-liquid collection tank 12, and fusel oil outlet pump 13. The bottom of column 4 is equipped with wastewater outlet pipeline 14, and wastewater outlet pump 15 is installed on wastewater outlet pipeline 14. One side of column 1 is connected to feed pipeline 16, and feed preheater 17 is installed on feed pipeline 16.

[0030] The pre-distillation column 1, side-stream column 2, pressurized column 3, and atmospheric column 4 are respectively equipped with a pre-column reboiler 18, a side-stream column reboiler 19, a pressurized column reboiler 20, and an atmospheric column reboiler 21. The gas drawn from the top of the atmospheric column 4 exchanges heat with the pre-column reboiler 18 and the side-stream column reboiler 19; the gas drawn from the top of the pressurized column 3 exchanges heat with the atmospheric column reboiler 21; the pressurized column reboiler 20 is heated by steam. Specifically, the input end of the pressurized column reboiler 20 is connected to the steam pipeline 22, and the output end of the pressurized column reboiler 20 is connected to the steam condensate collection pipeline 23; specifically, the top of the atmospheric column 4 is connected to the atmospheric column collection pipeline 24. The side-stream reboiler 19 is connected to the pre-reboiler 18 via the atmospheric distillation column outlet pipeline 25. The atmospheric distillation column outlet pipeline 24 is connected to the atmospheric distillation column outlet pipeline 25. The gas phase extracted from the top of the atmospheric distillation column 4 exchanges heat with the side-stream reboiler 19 and the pre-reboiler 18, respectively, to provide the heat required for distillation in the side-stream column 2 and the pre-rectification column 1. The top of the pressurized column 3 is connected to the atmospheric distillation column reboiler 21 via the pressurized column top outlet pipeline 26. The gas phase extracted from the top of the pressurized column 3 exchanges heat with the atmospheric distillation column reboiler 21, to provide the heat required for distillation in the atmospheric distillation column 4. In this embodiment, methanol with a concentration >99.99% and an ethanol content of 10-200 ppm can be extracted.

[0031] This embodiment is an improvement on the three-tower thermal coupling of methanol distillation. In addition to the original pre-distillation tower 1, pressurized tower 3, and atmospheric tower 4, a side-stream tower 2 is added. The loads of pre-distillation tower 1 and side-stream tower 2 are increased, while the loads of pressurized tower 3 and atmospheric tower 4 are decreased. The steam from the top of pressurized tower 3 provides heat to atmospheric tower 4, and simultaneously, the steam from the top of atmospheric tower 4 provides heat to pre-distillation tower 1 and side-stream tower 2. Refined methanol is collected from the tops of side-stream tower 2, pressurized tower 3, and atmospheric tower 4. The unit consumption of the methanol distillation process can be reduced from 1.2 t steam / t refined methanol to 0.7–0.8 t steam / t refined methanol. Compared to the traditional two-tower thermal coupling process, this can save more than half the energy, achieving a significant reduction in energy consumption, greatly reducing operating costs for enterprises, and improving their competitiveness. Furthermore, this embodiment can optimize the heat exchange network and further enhance energy-saving potential.

[0032] Preferably, the bottom of the pre-distillation column 1 is also connected to a pre-column reboiler 27, which is heated by steam. Specifically, the input end of the pre-column reboiler 27 is connected to the steam pipeline 22, and the output end of the pre-column reboiler 27 is connected to the steam condensate collection pipeline 23.

[0033] Example 2:

[0034] In this embodiment, the top of the pre-distillation column 1 is equipped with a pre-column top collection device, specifically:

[0035] The pre-distillation column top reflux device includes a pre-distillation column top reflux tank 28 connected to the top of the pre-distillation column 1. The bottom of the pre-distillation column top reflux tank 28 is connected to the pre-distillation column 1 via a pre-distillation column reflux pipeline 29. A pre-distillation column reflux pump 30 is installed on the pre-distillation column reflux pipeline 29. The upper part of the pre-distillation column top reflux tank 28 is connected to an extraction tank 32 via a reflux pipeline 31. A condenser 33 is installed on the reflux pipeline 31. A venting gas pipeline 34 is installed on the upper part of the extraction tank 32. An extraction water pipeline 35 is installed on one side of the extraction tank 32. The bottom of the extraction tank 32 is connected to... The extraction tank outlet pipeline 36 is connected to the pre-distillation column top reflux tank 28; the gas phase extracted from the top of the pre-distillation column 1 enters the pre-distillation column top reflux tank 28, and the gas phase in the pre-distillation column top reflux tank 28 is cooled by the condenser 33 and then enters the extraction tank 32. The non-condensable gas generated after extraction in the extraction tank 32 is discharged, and the liquid phase generated after extraction is refluxed to the pre-distillation column top reflux tank 28. The liquid phase in the pre-distillation column top reflux tank 28 is refluxed to the pre-distillation column 1. More specifically, the liquid phase in the pre-distillation column top reflux tank 28 is pressurized by the pre-distillation column reflux pump 30 and sent to the top of the pre-distillation column 1 as reflux feed.

[0036] The pre-distillation column 1 is provided with the heat required by the pre-distillation column 1 through indirect heating via the pre-column reboiler 18 and the pre-column reboiler 27. The heat source of the pre-column reboiler 18 is the gas phase taken from the top of the atmospheric column 4, and the heat source of the pre-column reboiler 27 is steam.

[0037] Example 3:

[0038] This embodiment provides a detailed description of the side-line tower 2, pressurization tower 3, and atmospheric pressure tower 4. Specifically:

[0039] The top of the side-stream tower 2 is connected to the side-stream tower top reflux tank 38 via a side-stream tower top outflow pipeline 37. A side-stream tower condenser 39 is installed on the side-stream tower top outflow pipeline 37. The bottom of the side-stream tower top reflux tank 38 is connected to the side-stream tower 2 via a side-stream tower reflux pipeline 40. A side-stream tower reflux pump 41 is installed on the side-stream tower reflux pipeline 40. The side-stream tower reflux pipeline 40 is connected to the side-stream tower refined methanol outflow pipeline 42 for outflowing refined methanol from the side-stream tower 2. The side-stream tower refined methanol outflow pipeline 42 is connected to the refined methanol tank 43. A single stream of material is taken from the pre-distillation tower 1. The gas phase from the top of the side-stream column 2 is distilled. After being condensed by the side-stream column condenser 39, the gas phase enters the side-stream column reflux tank 38. The liquid phase in the side-stream column reflux tank 38 is pressurized by the side-stream column reflux pump 41 and divided into two streams. One stream returns to the side-stream column 2, i.e., it is refluxed to the top of the side-stream column 2 as reflux feed. The other stream is used to collect refined methanol, which can be stored in the refined methanol tank 43. The side-stream column 2 is indirectly heated by the side-stream column reboiler 19, and the heat source of the side-stream column reboiler 19 is the gas phase collected from the top of the atmospheric column 4.

[0040] The top of the pressurized tower 3 is connected to the pressurized tower reflux tank 44 via pressurized tower top outlet pipeline 26 and pressurized tower top outlet pipeline 46. A pressurized tower condenser 45 is installed on pressurized tower top outlet pipeline 46. The bottom of the pressurized tower reflux tank 44 is connected to the pressurized tower 3 via pressurized tower reflux pipeline 47, on which a pressurized tower reflux pump 48 is installed. The pressurized tower reflux pipeline 47 is connected to the pressurized tower refined methanol outlet pipeline 49 for extracting refined methanol from the pressurized tower 3. The pressurized tower refined methanol outlet pipeline 49 can be directly connected to the refined methanol tank 43 or to the side-stream refined methanol outlet pipeline 42. The pressurized tower top outlet pipeline 26 is connected to the atmospheric pressure tower reboiler 21, and the atmospheric pressure tower reboiler 21 is connected to the pressurized tower reflux tank 44 via the atmospheric pressure tower reboiler outlet pipeline 50. The liquid phase collected from the bottom of the pre-distillation column 1 enters the pressurized column 3 for distillation. The vapor phase collected from the top of the pressurized column 3 is condensed by the pressurized column condenser 45 and then enters the pressurized column reflux tank 44. The liquid phase in the pressurized column reflux tank 44 is pressurized by the pressurized column reflux pump 48 and divided into two streams. One stream returns to the pressurized column 3, that is, it refluxes to the top of the pressurized column 3 as reflux feed, and the other stream is collected as refined methanol. The other vapor phase collected from the top of the pressurized column 3 exchanges heat with the atmospheric column reboiler 21 to provide heat for the distillation of the atmospheric column 4. The vapor phase after heat exchange with the atmospheric column reboiler 21 enters the pressurized column reflux tank 44. The pressurized column 3 is provided with the heat required for distillation by indirect heating through the pressurized column reboiler 20. The heat source of the pressurized column reboiler 20 is steam, and the steam pressure used by the pressurized column reboiler 20 is 0.7 MPa.

[0041] The top of the atmospheric pressure column 4 is connected to the atmospheric pressure column reflux tank 52 via atmospheric pressure column outlet pipeline 24 and atmospheric pressure column outlet pipeline 51. An atmospheric pressure column condenser 53 is installed on atmospheric pressure column outlet pipeline 51. The bottom of the atmospheric pressure column reflux tank 52 is connected to the atmospheric pressure column 4 via atmospheric pressure column reflux pipeline 54. An atmospheric pressure column reflux pump 55 is installed on atmospheric pressure column reflux pipeline 54. The atmospheric pressure column reflux pipeline 54 is connected to the atmospheric pressure column refined methanol outlet pipeline 56 for extracting refined methanol from the atmospheric pressure column 4. Pipeline 56 can be directly connected to the refined methanol tank 43 or to the refined methanol outflow pipeline 42 of the side-stream tower; the atmospheric tower outflow pipeline 24 is connected to the side-stream tower reboiler 19, and the side-stream tower reboiler 19 is connected to the atmospheric tower reflux tank 52 through the side-stream tower reboiler output pipeline 57; the atmospheric tower outflow pipeline 24 is connected to the atmospheric tower outflow pipeline 25, and the atmospheric tower outflow pipeline 25 is connected to the pre-tower reboiler 18, and the pre-tower reboiler 18 is connected to the atmospheric tower reflux tank 52 through the pre-tower reboiler output pipeline 58.

[0042] The liquid at the bottom of pressurized column 3 enters atmospheric column 4 for further distillation. The vapor phase collected from the top of atmospheric column 4 provides the heat required for distillation to the pre-column reboiler 18 and the side-stream reboiler 19, and then enters the atmospheric column reflux tank 52. The other part of the vapor phase collected from the top of atmospheric column 4 is condensed by atmospheric column condenser 53 and then directly enters the atmospheric column reflux tank 52. The liquid phase in the atmospheric column reflux tank 52 is pressurized by atmospheric column reflux pump 55 and divided into two streams. One stream flows back to atmospheric column 4, that is, it flows into the top of atmospheric column 4 as reflux feed, and the other stream is collected as refined methanol. Atmospheric column 4 is indirectly heated by atmospheric column reboiler 21, which is the heat source of atmospheric column reboiler 21. The heat source of atmospheric column reboiler 21 is the vapor phase collected from the top of pressurized column 3. The side stream of atmospheric column 4 is collected as fusel oil, and the bottom of the column is collected as wastewater.

[0043] Example 4:

[0044] This application provides a specific application scenario, specifically:

[0045] At a methanol plant, a new crude methanol refining and recovery unit with an annual output of 660,000 tons was installed. The feed rate was 96,720 kg / h. When the process parameters were optimized to the best, the steam energy consumption for refined methanol was about 0.7 tons of steam / refined methanol, with the methanol purity reaching over 99.99% and the ethanol content less than 500 ppm.

[0046] In this embodiment, the methanol content is 87.8%, the water content is 9.46%, and the ethanol content is approximately 3096 ppm. The crude methanol is preheated to 60°C by the feed preheater 17 before entering the pre-distillation column 1. The operating parameters of each column are shown in Table 1 below:

[0047]

[0048] Table 1

[0049] The working principle of this embodiment is as follows:

[0050] Crude methanol enters the feed preheater 17 for preheating, which raises the crude methanol to approximately 60°C. The preheated crude methanol then enters the pre-distillation column 1 for distillation. The top pressure of the pre-distillation column 1 is 108 kPa, the top temperature is 40°C, and the bottom temperature is 75°C. The vapor phase collected from the top of the pre-distillation column 1 enters the pre-distillation column top reflux tank 28. After being cooled by the condenser 33, the vapor phase in the pre-distillation column top reflux tank 28 enters the extraction tank 32. The non-condensable gas produced after extraction in the extraction tank 32 is discharged, and the liquid phase produced after extraction is refluxed back to the pre-distillation column top reflux tank 28. 8. Then, the liquid phase in the pre-distillation column reflux tank 28 is refluxed to the pre-distillation column 1. More specifically, the liquid phase in the pre-distillation column reflux tank 28 is pressurized by the pre-distillation column reflux pump 30 and sent to the top of the pre-distillation column 1 as reflux feed. The pre-distillation column 1 is provided with the heat required for distillation by indirect heating through the pre-distillation column reboiler 18 and the pre-distillation column reboiler 27. The heat source of the pre-distillation column reboiler 27 is steam, which heats the pre-distillation column reboiler 27 at a pressure of 0.7 MPa. The heat source of the pre-distillation column reboiler 18 is the gas phase taken from the top of the atmospheric column 4.

[0051] A stream of material is drawn from the pre-distillation column 1 and fed into the side-stream column 2 for distillation. The top pressure of the side-stream column 2 is 59 kPa, the top temperature is 51°C, and the bottom temperature is 56°C. The vapor phase drawn from the top of the side-stream column 2 is condensed by the side-stream column condenser 39 and then enters the side-stream column top reflux tank 38. The liquid phase in the side-stream column top reflux tank 38 is pressurized by the side-stream column reflux pump 41 and divided into two streams. One stream returns to the side-stream column 2, that is, it is refluxed to the top of the side-stream column 2 as reflux feed, and the other stream is collected as refined methanol.

[0052] The liquid phase collected from the bottom of the pre-distillation column 1 enters the pressurized column 3 for distillation via the pre-column outlet pump 7. The pressure at the top of the pressurized column 3 is 718 kPa, the temperature at the top is 124°C, and the temperature at the bottom is 134°C. The vapor phase collected from the top of the pressurized column 3 is condensed by the pressurized column condenser 45 and then enters the pressurized column reflux tank 44. The liquid phase in the pressurized column reflux tank 44 is pressurized by the pressurized column reflux pump 48 and then divided into two streams. One stream returns to the pressurized column 3, i.e., it refluxes to the top of the pressurized column 3 as reflux feed, and the other stream is collected as refined methanol. The pressurized column 3 is indirectly heated by the pressurized column reboiler 20, which provides the heat required for distillation. The heat source for the pressurized column reboiler 20 is steam, and the steam pressure used by the pressurized column reboiler 20 is 0.7 MPa.

[0053] The liquid at the bottom of pressurized column 3 enters atmospheric column 4 for further distillation. The top pressure of atmospheric column 4 is 182 kPa, the top temperature is 80°C, and the bottom temperature is 118°C. The vapor phase collected from the top of atmospheric column 4 provides the heat required for distillation to the pre-column reboiler 18 and the side-stream reboiler 19. Then, it enters the atmospheric column reflux tank 52. The liquid phase in the atmospheric column reflux tank 52 is pressurized by the atmospheric column reflux pump 55 and divided into two streams. One stream flows back to atmospheric column 4, i.e., it flows into the top of atmospheric column 4 as reflux feed, and the other stream is used to collect refined methanol. Atmospheric column 4 is indirectly heated by atmospheric column reboiler 21, which is the heat source of atmospheric column reboiler 21. The heat source of atmospheric column reboiler 21 is the vapor phase collected from the top of pressurized column 3. The side stream of atmospheric column 4 is used to collect fusel oil, and the bottom is used to collect wastewater.

[0054] In this embodiment, the pre-tower reboiler 27 and the pressurized tower reboiler 20 use steam as a heat source. The methanol vapor at the top of the pressurized tower 3 provides heat to the atmospheric tower reboiler 21, and the methanol vapor at the top of the atmospheric tower 4 provides heat to the pre-tower reboiler 18 and the side-stream tower reboiler 19. The energy consumption per ton of refined methanol is about 0.7t of steam.

[0055] Through the above scheme, this application can expand capacity by more than 50% while reducing steam consumption by 50%-55%. For the transformation of the traditional three-tower market, the investment is small and the operation is highly feasible. By adopting energy-saving measures such as optimizing heat recovery through heat exchange networks, steam consumption can be greatly reduced, and the consumption per ton of methanol can be reduced to less than 0.7 tons of steam / ton of refined methanol.

[0056] In summary, by adopting the above-mentioned technical solutions, this application employs a thermal coupling process of a pre-distillation tower, a side-stream tower, a pressurized tower, and an atmospheric tower, optimizing the heat exchange network and increasing energy-saving potential. It can produce methanol with a concentration >99.99% and an ethanol content of 10-200ppm. The process only requires modifications to the existing pre-distillation tower, pressurized tower, and atmospheric tower, resulting in low modification costs. Compared with traditional methanol processes, it can reduce steam consumption to 0.7-0.8t steam / t refined alcohol, achieving a significant reduction in energy consumption.

[0057] The devices and connections not specifically described above are all existing technologies, and will not be described in detail here.

[0058] 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.

[0059] 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.

[0060] 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 refining apparatus, comprising a pre-distillation column (1), characterized in that, The pre-distillation column (1) is connected to the side-stream column (2) and the pressurized column (3) respectively. The pressurized column (3) is connected to the atmospheric column (4). The pre-distillation column (1), the side-stream column (2), the pressurized column (3), and the atmospheric column (4) are respectively equipped with a pre-column reboiler (18), a side-stream column reboiler (19), a pressurized column reboiler (20), and an atmospheric column reboiler (21). The gas drawn from the top of the atmospheric column (4) exchanges heat with the pre-column reboiler (18) and the side-stream column reboiler (19). The gas drawn from the top of the pressurized column (3) exchanges heat with the atmospheric column reboiler (21).

2. The crude methanol refining apparatus according to claim 1, characterized in that, The top of the atmospheric tower (4) is connected to the side tower reboiler (19) and the pre-tower reboiler (18) through the atmospheric tower outlet pipeline (24) and the atmospheric tower outlet pipeline (25), respectively; the top of the pressurized tower (3) is connected to the atmospheric tower reboiler (21) through the pressurized tower top outlet pipeline (26).

3. The crude methanol refining apparatus according to claim 1, characterized in that, The top of the pre-distillation column (1) is equipped with a top pre-column sampling device.

4. The crude methanol refining apparatus according to claim 3, characterized in that, The pre-distillation tower top collection device includes a pre-distillation tower top reflux tank (28) connected to the top of the pre-distillation tower (1). The bottom of the pre-distillation tower top reflux tank (28) is connected to the pre-distillation tower (1) through a pre-distillation tower reflux line (29). The upper part of the pre-distillation tower top reflux tank (28) is connected to the extraction tank (32) through a collection line (31). A condenser (33) is installed on the collection line (31). A venting gas line (34) is installed on the upper part of the extraction tank (32). An extraction water line (35) is installed on one side of the extraction tank (32). The bottom of the extraction tank (32) is connected to the pre-distillation tower top reflux tank (28) through an extraction tank collection line (36).

5. The crude methanol refining apparatus according to claim 1, characterized in that, The top of the side-stream tower (2) is connected to the side-stream tower top reflux tank (38) via the side-stream tower top extraction pipeline (37). A side-stream tower condenser (39) is installed on the side-stream tower top extraction pipeline (37). The bottom of the side-stream tower top reflux tank (38) is connected to the side-stream tower (2) via the side-stream tower reflux pipeline (40). A side-stream tower reflux pump (41) is installed on the side-stream tower reflux pipeline (40). The side-stream tower reflux pipeline (40) is connected to the side-stream tower refined methanol extraction pipeline (42).

6. The crude methanol refining apparatus according to claim 2, characterized in that, The top of the pressurization tower (3) is connected to the pressurization tower reflux tank (44) through pressurization tower top outlet pipeline one (26) and pressurization tower top outlet pipeline two (46). A pressurization tower condenser (45) is installed on the pressurization tower top outlet pipeline two (46). The bottom of the pressurization tower reflux tank (44) is connected to the pressurization tower (3) through pressurization tower reflux pipeline (47). A pressurization tower reflux pump (48) is installed on the pressurization tower reflux pipeline (47). The pressurization tower reflux pipeline (47) is connected to the pressurization tower refined methanol outlet pipeline (49).

7. A crude methanol refining apparatus according to claim 6, characterized in that, The atmospheric pressure tower reboiler (21) is connected to the pressurized tower reflux tank (44) through the atmospheric pressure tower reboiler output pipeline (50).

8. A crude methanol refining apparatus according to claim 2, characterized in that, The top of the atmospheric tower (4) is connected to the atmospheric tower reflux tank (52) through the atmospheric tower outlet pipeline (24) and the second atmospheric tower outlet pipeline (51). An atmospheric tower condenser (53) is installed on the second atmospheric tower outlet pipeline (51). The bottom of the atmospheric tower reflux tank (52) is connected to the atmospheric tower (4) through the atmospheric tower reflux pipeline (54). An atmospheric tower reflux pump (55) is installed on the atmospheric tower reflux pipeline (54). The atmospheric tower reflux pipeline (54) is connected to the atmospheric tower refined methanol outlet pipeline (56).

9. A crude methanol refining apparatus according to claim 8, characterized in that, The side-stream reboiler (19) is connected to the atmospheric pressure tower reflux tank (52) via the side-stream reboiler output line (57); the pre-tower reboiler (18) is connected to the atmospheric pressure tower reflux tank (52) via the pre-tower reboiler output line (58).

10. A crude methanol refining apparatus according to claim 1, characterized in that, The bottom of the pre-distillation column (1) is also connected to a pre-column reboiler (27), the output end of which is connected to the steam pipeline (22), and the output end of the pre-column reboiler (27) is connected to the steam condensate collection pipeline (23).

Images