A five-tower thermally coupled refining device for crude methanol

Abstract

This application provides a five-tower thermally coupled refining apparatus for crude methanol, comprising a pre-distillation tower, an atmospheric distillation tower, a medium-pressure distillation tower, a pressure distillation tower I, and a pressure distillation tower II connected in sequence. The top of the pre-distillation tower is connected to the reboiler of the atmospheric distillation tower I, the top of the medium-pressure distillation tower is connected to the reboiler of the pre-distillation tower, the top of the pressure distillation tower I is connected to the reboilers of the medium-pressure distillation tower and the reboiler of the pressure distillation tower II, and the top of the pressure distillation tower II is connected to the reboiler of the atmospheric distillation tower II through a top outlet pipeline of the pressure distillation tower II. In this application, the top steam of the pressurized distillation column one provides heat to the medium-pressure distillation column and the pressurized distillation column two. The top steam of the medium-pressure distillation column provides heat to the pre-distillation column. The top steam of the pre-distillation column and the pressurized distillation column two provide heat to the atmospheric distillation column, thus making full use of the heat at the top of each distillation column. Through this application, the unit consumption of the methanol distillation process can be reduced from 1.2t steam / t refined methanol to 0.50-0.60t steam / t refined methanol, achieving a significant reduction in energy consumption.

Description

Technical Field

[0001] The present application relates to the field of chemical technology, and in particular to a five-tower thermally coupled refining device for crude methanol. Background Art

[0002] Methanol is a widely used basic chemical raw material, which is applied to fine chemicals, polymers, pesticides, medicines, energy, fuel cells and many other fields. It plays an extremely important role in the international chemical market. Crude methanol usually contains light impurities such as dimethyl ether and heavy impurities such as ethanol and water. It is necessary to remove various impurities through the distillation process to obtain refined methanol products that meet the quality requirements. Therefore, in the production process of methanol, distillation is a key separation operation. The traditional methanol distillation process usually adopts a three-tower process of pre-tower, pressurized tower and atmospheric tower, and uses the steam from the top of the pressurized tower to heat the atmospheric tower to achieve the purpose of energy saving. However, the atmospheric tower and the top of the pre-tower use circulating water for cooling, which leads to a large amount of heat being wasted, making the steam unit consumption of the entire system high, about 1.2t steam / t refined alcohol. A new technology is needed to recover the heat in the original system to achieve the goal of energy saving and emission reduction.

[0003] The emergence of heat pump technology and thermal coupling technology has brought great improvement prospects for energy conservation and emission reduction in the methanol industry. For example, it has been gradually replaced by the three-tower double-effect distillation and four-tower double-effect distillation processes (three towers plus recovery tower) developed by Lurgi, Germany. At present, the domestic methanol distillation units that have been recently put into production and are under construction mostly adopt three-tower double-effect or four-tower double-effect distillation processes. However, with the background of increasingly stringent carbon emission indicators, new technologies are bound to replace existing technologies to achieve the demand for lower steam unit consumption of refined methanol products, among which multi-effect distillation technology and heat pump technology have significant advantages; multi-effect distillation technology refers to dividing the entire distillation process into multiple towers with different energy levels, using the top steam of the tower with a higher temperature to heat the reboiler of the tower with a lower temperature, and condensing the steam at the same time. In this way, in the multi-effect distillation, the methanol vapor generated at the top of the tower with a higher temperature is used to exchange heat for the reboilers of other towers, realizing the condensation of methanol vapor, and meeting the reboiler heat demand of the thermal coupling tower kettle, which can greatly reduce steam consumption and achieve significant energy saving effects.

[0004] For example, a five-tower four-effect crude methanol refining device with application number CN202321881315.2 in the prior art discloses a technical solution, including a pre-distillation tower, a negative pressure distillation tower, a pressurized distillation tower, a normal pressure distillation tower, and a recovery tower. It adopts two forms of thermal coupling. For the existing market, it can achieve the purpose of expanding the capacity of the traditional three-tower methanol distillation process by more than 30%, while reducing steam consumption by 45%-50%; for the new market, it has small investment and strong operability, and adopts energy-saving measures such as heat exchange network optimization and heat recovery, which greatly reduces steam consumption. Consumption, the steam consumption per ton of methanol can be reduced to less than 0.62 tons of steam; however, in the scheme in the application, there are mainly two forms, one is that the pre-tower reboiler 1, the pressurized distillation tower reboiler, and the recovery tower reboiler are respectively connected to the steam pipeline, and the steam is used for heating; the other is that the pre-tower reboiler 2, the pressurized distillation tower reboiler, and the recovery tower reboiler are respectively connected to the steam pipeline, and the steam is used for heating; that is, in this scheme, at least three distillation tower reboilers need to be heated by external steam, and the heat at the top of each tower is not fully utilized. Therefore, the energy-saving effect is relatively poor.

[0005] In a five-tower, five-effect crude methanol refining device with application number 2024206756986, the heat at the top of each tower is fully utilized. However, the utilization of heat in this application requires a vacuum pump, and the safety is relatively poor.

[0006] In summary, it is necessary to provide a new technical solution to solve the above technical problems. Utility Model Content

[0007] The present application provides a crude methanol five-tower thermal coupling refining device, comprising a pre-distillation tower, an atmospheric distillation tower, and a pressure distillation tower 1, wherein a medium-pressure distillation tower is arranged between the atmospheric distillation tower and the pressure distillation tower 1, a pressure distillation tower 2 is arranged at the rear of the pressure distillation tower 1, and a pre-tower reboiler, a medium-pressure tower reboiler, a pressure tower 1 reboiler, and a pressure tower 2 reboiler are arranged at the lower parts of the pre-distillation tower, the medium-pressure distillation tower, the pressure distillation tower 1, and the pressure distillation tower 2, respectively, and the lower part of the atmospheric distillation tower is provided with a Atmospheric pressure tower reboiler one, atmospheric pressure tower reboiler two; the top of the pre-distillation tower is connected to the atmospheric pressure tower reboiler one through the pre-tower top extraction pipeline, the top of the medium-pressure distillation tower is connected to the pre-tower reboiler through the medium-pressure tower top extraction pipeline, the top of the pressurized distillation tower one is connected to the medium-pressure tower reboiler and the pressurized tower two reboiler through the pressurized tower one top extraction pipeline one and the pressurized tower one top extraction pipeline two respectively, and the top of the pressurized distillation tower two is connected to the atmospheric pressure tower reboiler two through the pressurized tower two top extraction pipeline.

[0008] As a preferred solution, a pre-tower reboiler 1 is provided at the lower part of the pre-distillation tower, the input end of the pre-tower reboiler 1 is connected to the steam pipeline, and the output end of the pre-tower reboiler 1 is connected to the steam condensate extraction pipeline.

[0009] As a preferred solution, the atmospheric tower reboiler is connected to the pre-tower reflux device.

[0010] As a preferred embodiment, the pre-tower reflux device includes a pre-tower top reflux tank, the bottom of which is connected to the upper part of the pre-distillation tower through a pre-tower reflux pipeline, the pre-tower top reflux tank is connected to the bottom of the extraction tank through pipeline one, an extraction water pipeline is provided on one side of the extraction tank, and a purge gas pipeline is provided on the top of the extraction tank; the pre-tower top reflux tank is also connected to the upper part of the extraction tank through pipeline two, and a pre-tower top reflux tank condenser is provided on pipeline two.

[0011] As a preferred solution, the pre-tower reboiler is connected to the medium-pressure tower reflux device.

[0012] As a preferred embodiment, the medium-pressure tower reflux device includes a medium-pressure tower reflux tank, the bottom of the medium-pressure tower reflux tank is connected to the upper part of the medium-pressure distillation tower through a medium-pressure tower reflux pipeline, and the medium-pressure tower reflux pipeline is connected to a medium-pressure tower refined methanol production pipeline.

[0013] As a preferred solution, the refined methanol production pipeline of the medium-pressure tower is connected to the refined methanol tank.

[0014] As a preferred solution, the medium-pressure tower reboiler and the pressure tower second reboiler are respectively connected to the pressure tower first reflux device.

[0015] As a preferred embodiment, the pressure tower reflux device includes a pressure tower reflux tank, the bottom of the pressure tower reflux tank is connected to the upper part of the pressure distillation tower through a pressure tower reflux pipeline, and the pressure tower reflux pipeline is connected to a pressure tower refined methanol extraction pipeline.

[0016] As a preferred solution, the refined methanol production pipeline of the pressure tower is connected to the refined methanol tank.

[0017] As a preferred solution, the atmospheric tower reboiler 2 is connected to the pressure tower 2 reflux device.

[0018] As a preferred embodiment, the pressure tower two reflux device includes a pressure tower two reflux tank, the bottom of the pressure tower two reflux tank is connected to the upper part of the pressure distillation tower two through a pressure tower two reflux pipeline, and the pressure tower two reflux pipeline is connected to the pressure tower two refined methanol extraction pipeline.

[0019] As a preferred solution, the refined methanol production pipeline of the pressure tower is connected to the refined methanol tank.

[0020] As a preferred embodiment, the pressurized distillation tower 2 is connected to the pressurized tower 2 reflux tank through the pressurized tower 2 top production pipeline 1, the pressurized tower 2 top production pipeline 1 is connected to the pressurized tower 2 top production pipeline, and the pressurized tower 2 top condenser is arranged on the pressurized tower 2 top production pipeline 1.

[0021] As a preferred solution, an atmospheric distillation tower reflux device is provided at the top of the atmospheric distillation tower.

[0022] As a preferred embodiment, the atmospheric tower reflux device includes an atmospheric tower reflux tank, the top of the atmospheric distillation tower is connected to the atmospheric tower reflux tank through an atmospheric tower top extraction pipeline, an atmospheric tower top condenser is arranged on the atmospheric tower top extraction pipeline, the bottom of the atmospheric tower reflux tank is connected to the upper part of the atmospheric distillation tower through an atmospheric tower reflux pipeline, an atmospheric tower extraction pump is arranged on the atmospheric tower reflux pipeline, and the atmospheric tower refined methanol extraction pipeline is connected to the atmospheric tower reflux pipeline.

[0023] The present application adopts a five-tower device including a pre-distillation tower, an atmospheric distillation tower, a medium-pressure distillation tower, a pressurized distillation tower 1, and a pressurized distillation tower 2. Compared with the traditional three-tower device, a medium-pressure distillation tower and a pressurized distillation tower 2 are added, and a five-tower thermal coupling device is adopted to optimize the heat exchange network and improve energy saving space; the top steam of the original pressurized distillation tower 1 is used to provide heat for the newly added medium-pressure distillation tower and the pressurized distillation tower 2, and at the same time, the top steam of the newly added medium-pressure distillation tower provides heat for the pre-distillation tower, and the top steam of the pre-distillation tower and the newly added pressurized distillation tower 2 provides heat for the atmospheric distillation tower, so that the heat at the top of each distillation tower is fully utilized; through the present application, the traditional device can be transformed, and the unit consumption of the methanol distillation process can be reduced from 1.2t steam / t refined alcohol to 0.50-0.60t steam / t refined alcohol, achieving a significant reduction in energy consumption, greatly reducing the operating cost for the enterprise and improving the competitiveness of the enterprise; and the use of heat in the application does not require a vacuum pump, and has good safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of this application;

[0025] 1. Pre-distillation tower; 2. Atmospheric distillation tower; 3. Medium-pressure distillation tower; 4. Pressure distillation tower 1; 5. Pressure distillation tower 2; 6. Feed pipeline; 7. Crude methanol feed preheater; 8. Pre-tower kettle extraction pipeline; 9. Atmospheric tower kettle extraction pipeline; 10. Atmospheric tower kettle pump; 11. Medium-pressure tower kettle extraction pipeline; 12. Medium-pressure tower kettle pump; 13. Pressure tower 1 kettle extraction pipeline; 14. Pressure tower 2 kettle extraction pipeline; 15. Pressure tower 2 kettle pump; 16. Pressure tower 2 side extraction pipeline; 17. Condenser; 18. Buffer tank; 19. Side extraction pump; 20. Pre-tower reboiler; 21, medium-pressure tower reboiler; 22, pressure tower one reboiler; 23, pressure tower two reboiler; 24, atmospheric tower reboiler one; 25, atmospheric tower reboiler two; 26, pre-tower top extraction pipeline; 27, medium-pressure tower top extraction pipeline; 28, pressure tower one top extraction pipeline one; 29, pressure tower one top extraction pipeline two; 30, steam pipeline; 31, steam condensate extraction pipeline; 32, pre-tower reboiler one; 33, pre-tower top reflux tank; 34, atmospheric tower reboiler one output pipeline; 35, pre-tower reflux pipeline; 36, pre-tower reflux pump; 3 7. Pipeline 1; 38. Extraction tank; 39. Extraction water pipeline; 40. Purge gas pipeline; 41. Pipeline 2; 42. Reflux tank condenser at top of pre-tower; 43. Reflux tank of medium-pressure tower; 44. Pre-tower reboiler output pipeline; 45. Reflux pipeline of medium-pressure tower; 46. Extraction pump of medium-pressure tower; 47. Extraction pipeline of refined methanol of medium-pressure tower; 48. Refined methanol tank; 49. Reflux tank of pressure tower 1; 50. Reboiler output pipeline of medium-pressure tower; 51. Reboiler output pipeline of pressure tower 2; 52. Reflux pipeline of pressure tower 1; 53. Reflux pump of pressure tower 1; 54. Refined methanol of pressure tower 1 Production pipeline; 55, reflux tank of pressure tower two; 56, reflux pipeline of pressure tower two; 57, circulation pump of pressure tower two; 58, refined methanol production pipeline of pressure tower two; 59, production pipeline one at the top of pressure tower two; 60, condenser at the top of pressure tower two; 61, reflux tank of atmospheric tower; 62, output pipeline of reboiler two of atmospheric tower; 63, production pipeline at the top of atmospheric tower; 64, condenser at the top of atmospheric tower; 65, reflux pipeline of atmospheric tower; 66, production pump of atmospheric tower; 67, refined methanol production pipeline of atmospheric tower; 68, refined methanol production pipeline; 69, production pipeline at the top of pressure tower two. DETAILED DESCRIPTION

[0026] The following is combined with Figure 1 The specific implementation of the utility model is described in detail. It should be noted that the specific implementation described here is only used to illustrate and explain the utility model, and is not used to limit the utility model.

[0027] Embodiment 1:

[0028] The present application provides a five-tower thermally coupled crude methanol refining device, comprising a pre-distillation tower 1, an atmospheric distillation tower 2, a medium-pressure distillation tower 3, a pressure distillation tower 1 4, and a pressure distillation tower 2 5 connected in sequence;

[0029] Preferably, the top pressure of the pre-distillation tower 1 is 150-180 kPa, the top pressure of the atmospheric distillation tower 2 is 100-120 kPa, the top pressure of the medium-pressure distillation tower 3 is 250-350 kPa, the top pressure of the pressure distillation tower 1 4 is 700-800 kPa, and the top pressure of the pressure distillation tower 2 5 is 150-200 kPa;

[0030] A feed pipeline 6 is provided on one side of the pre-distillation tower 1, and a crude methanol feed preheater 7 is provided on the feed pipeline 6, which is used to preheat the crude methanol material entering the pre-distillation tower 1 to improve the stability of distillation; the bottom of the pre-distillation tower 1 is connected to the atmospheric distillation tower 2 through a pre-tower kettle extraction pipeline 8, and the bottom of the atmospheric distillation tower 2 is connected to the medium-pressure distillation tower 3 through an atmospheric pressure tower kettle extraction pipeline 9, and an atmospheric pressure tower kettle pump 10 is provided on the atmospheric pressure tower kettle extraction pipeline 9; the bottom of the medium-pressure distillation tower 3 is connected to the pressurized distillation tower 4 through a medium-pressure tower kettle extraction pipeline 11, and the medium-pressure tower kettle extraction pipeline 11 is connected to the pressurized distillation tower 4 through a medium-pressure tower kettle extraction pipeline 11. A medium-pressure tower kettle pump 12 is provided; the bottom of the pressurized distillation tower 1 4 is connected to the pressurized distillation tower 2 5 through the pressurized tower 1 kettle extraction pipeline 13, and the bottom of the pressurized distillation tower 2 5 is provided with a pressurized tower 2 kettle extraction pipeline 14 for extracting waste water, and a pressurized tower 2 kettle pump 15 is provided on the pressurized tower 2 kettle extraction pipeline 14; a pressurized tower 2 side extraction pipeline 16 is provided on one side of the pressurized distillation tower 2 5, and the pressurized tower 2 side extraction pipeline 16 is used to extract fusel alcohol, and a condenser 17 is provided on the pressurized tower 2 side extraction pipeline 16, and a buffer tank 18 and a side extraction pump 19 are sequentially provided at the rear of the condenser 17;

[0031] The lower parts of the pre-distillation tower 1, the medium-pressure distillation tower 3, the pressure distillation tower 1 4, and the pressure distillation tower 2 5 are respectively provided with a pre-tower reboiler 20, a medium-pressure tower reboiler 21, a pressure tower 1 reboiler 22, and a pressure tower 2 reboiler 23; the lower part of the atmospheric distillation tower 2 is provided with an atmospheric tower reboiler 1 24 and an atmospheric tower reboiler 25; the top of the pre-distillation tower 1 is connected to the atmospheric tower reboiler 1 24 through a pre-tower top extraction pipeline 26, and the material extracted from the top of the pre-distillation tower 1 is heat exchanged with the atmospheric tower reboiler 1 24. After the heat exchange, The material is refluxed to the pre-distillation tower 1, and the heat from the top of the pre-distillation tower 1 is used to heat the atmospheric tower reboiler 24, thereby improving the utilization rate of heat; the top of the medium-pressure distillation tower 3 is connected to the pre-tower reboiler 20 through the medium-pressure tower top extraction pipeline 27, and the material extracted from the top of the medium-pressure distillation tower 3 is heat-exchanged with the pre-tower reboiler 20, and the material after heat exchange is refluxed to the medium-pressure distillation tower 3, and the heat from the top of the medium-pressure distillation tower 3 is used to heat the pre-tower reboiler 20, thereby improving the utilization rate of heat; the top of the pressurized distillation tower 4 is connected to the pre-tower reboiler 20 through the medium-pressure tower top extraction pipeline 27, and the material extracted from the top of the medium-pressure distillation tower 3 is heat-exchanged with the pre-tower reboiler 20, thereby improving the utilization rate of heat The extraction pipeline 1 28 of the top of the pressure tower 1 and the extraction pipeline 2 29 of the top of the pressure tower 1 are connected to the reboiler 21 of the medium-pressure tower and the reboiler 23 of the pressure tower 2 respectively. The materials extracted from the top of the pressure distillation tower 1 4 are heat-exchanged with the reboiler 21 of the medium-pressure tower and the reboiler 23 of the pressure tower 2 respectively. The materials after heat exchange are refluxed to the pressure distillation tower 1 4. The heat of the top of the pressure distillation tower 1 4 is used to heat the reboiler 21 of the medium-pressure tower and the reboiler 23 of the pressure tower 2 respectively, so as to improve the utilization rate of heat. The top of the pressure distillation tower 2 5 is connected to the reboiler 21 of the medium-pressure tower and the reboiler 23 of the pressure tower 2 through the top of the pressure tower 2. The extraction pipeline 69 is connected to the atmospheric tower reboiler 25; the material extracted from the top of the pressurized distillation tower 25 is heat-exchanged with the atmospheric tower reboiler 25, and the heat-exchanged material is refluxed to the pressurized distillation tower 25, and the heat from the top of the pressurized distillation tower 25 is used to heat the atmospheric tower reboiler 25, thereby improving the utilization rate of heat; the pressurized tower reboiler 22 is heated by steam, specifically, the input end of the pressurized tower reboiler 22 is connected to the steam pipeline 30, and the output end of the pressurized tower reboiler 22 is connected to the steam condensate extraction pipeline 31;

[0032] In order to provide the heat required for startup, a pre-tower reboiler 32 is further provided at the lower part of the pre-distillation tower 1, the input end of the pre-tower reboiler 32 is connected to the steam pipeline 30, and the output end of the pre-tower reboiler 32 is connected to the steam condensate extraction pipeline 31, so that the heat required for startup is provided to the pre-distillation tower 1 through steam, and after the startup is stable, the steam heating can be turned off;

[0033] In the present embodiment, a five-tower process of a pre-distillation tower 1, an atmospheric distillation tower 2, a medium-pressure distillation tower 3, a pressurized distillation tower 1 4, and a pressurized distillation tower 2 5 is adopted. Compared with the traditional three-tower process, a medium-pressure distillation tower 3 and a pressurized distillation tower 2 5 are added, and a five-tower thermal coupling process is adopted to optimize the heat exchange network and increase the energy-saving space. In the present embodiment, the purpose of energy saving and consumption reduction is achieved through a multi-effect thermal coupling method, that is, after stable start-up, only the reboiler 22 of the pressurized tower 1 is heated by steam, and the top steam of the original pressurized distillation tower 1 4 is used to provide heat for the newly added medium-pressure distillation tower 3 and the pressurized distillation tower 2 5. At the same time, the top steam of the newly added medium-pressure distillation tower 3 provides heat for the pre-distillation tower 1, and the top steam of the pre-distillation tower 1 and the newly added pressurized distillation tower 2 5 provides heat for the atmospheric distillation tower 2. The heat at the top of each distillation tower is fully utilized, thereby achieving the purpose of energy saving and consumption reduction, and greatly realizing energy saving.

[0034] Embodiment 2:

[0035] In this embodiment, the pre-tower reflux device at the top of the pre-distillation tower 1, the atmospheric tower reflux device at the top of the atmospheric distillation tower 2, the medium-pressure tower reflux device at the top of the medium-pressure distillation tower 3, the pressure tower 1 reflux device at the top of the pressure distillation tower 1 4, and the pressure tower 2 reflux device at the top of the pressure distillation tower 2 5 are described, specifically:

[0036] The atmospheric tower reboiler 24 is connected to the pre-tower reflux device; the pre-tower reflux device includes a pre-tower top reflux tank 33, the atmospheric tower reboiler output pipeline 34 at the output end of the atmospheric tower reboiler 24 is connected to the pre-tower top reflux tank 33, the bottom of the pre-tower top reflux tank 33 is connected to the upper part of the pre-distillation tower 1 through a pre-tower reflux pipeline 35 for reflux, and a pre-tower reflux pump 36 is provided on the pre-tower reflux pipeline 35; the pre-tower top reflux tank 33 is connected to the bottom of the extraction tank 38 through a pipeline 37, an extraction water pipeline 39 is provided on one side of the extraction tank 38, and a purge gas pipeline 40 is provided on the top of the extraction tank 38; The pre-tower top reflux tank 33 is also connected to the upper part of the extraction tank 38 through a pipeline 2 41, and a pre-tower top reflux tank condenser 42 is provided on the pipeline 2 41; the material extracted from the top of the pre-distillation tower 1 is heat-exchanged with the atmospheric tower reboiler 24 to realize the utilization of the heat at the top of the pre-distillation tower 1, and the material after heat exchange enters the pre-tower top reflux tank 33, and the liquid phase of the pre-tower top reflux tank 33 refluxes to the pre-distillation tower 1, and the non-condensable gas in the pre-tower top reflux tank 33 is cooled by the pre-tower top reflux tank condenser 42 and then enters the extraction tank 38, and the liquid phase of the extraction tank 38 flows into the pre-tower top reflux tank 33, and the non-condensable gas is extracted through the purge gas pipeline 40.

[0037] The pre-tower reboiler 20 is connected to the medium-pressure tower reflux device, and the medium-pressure tower reflux device includes a medium-pressure tower reflux tank 43. The pre-tower reboiler output pipeline 44 at the output end of the pre-tower reboiler 20 is connected to the medium-pressure tower reflux tank 43. The bottom of the medium-pressure tower reflux tank 43 is connected to the upper part of the medium-pressure distillation tower 3 through a medium-pressure tower reflux pipeline 45, which is used to increase the extraction concentration of refined methanol; a medium-pressure tower extraction pump 46 is provided on the medium-pressure tower reflux pipeline 45, and the medium-pressure tower reflux pipeline 45 is connected to the medium-pressure tower reflux tank 43. A medium-pressure tower refined methanol production pipeline 47 is connected to line 45; further, the medium-pressure tower refined methanol production pipeline 47 is connected to a refined methanol tank 48 for storing refined methanol; the material produced from the top of the medium-pressure distillation tower 3 is heat-exchanged with the pre-tower reboiler 20 to realize the utilization of the heat from the top of the medium-pressure distillation tower 3, and the material after heat exchange enters the medium-pressure tower reflux tank 43, and the liquid phase of the medium-pressure tower reflux tank 43 is partially refluxed to the medium-pressure distillation tower 3, and part is produced as refined methanol.

[0038] The medium-pressure tower reboiler 21 and the pressure tower second reboiler 23 are respectively connected to the pressure tower first reflux device; the pressure tower first reflux device includes a pressure tower first reflux tank 49, and the output ends of the medium-pressure tower reboiler 21 and the pressure tower second reboiler 23 are respectively connected to the pressure tower first reflux tank 49 through the medium-pressure tower reboiler output pipeline 50 and the pressure tower second reboiler output pipeline 51; the bottom of the pressure tower first reflux tank 49 is connected to the upper part of the pressure distillation tower 4 through the pressure tower first reflux pipeline 52, so as to increase the extraction concentration of refined methanol; the pressure tower first reflux pipeline 52 is connected to the pressure tower first reflux tank 49 through the pressure tower first reflux pipeline 52. A pressure tower-1 reflux pump 53 is provided, and a pressure tower-1 refined methanol production pipeline 54 is connected to the pressure tower-1 reflux pipeline 52, and the pressure tower-1 refined methanol production pipeline 54 is connected to the refined methanol tank 48 for storing refined methanol; the material produced from the top of the pressure distillation tower-4 is heat-exchanged with the medium-pressure tower reboiler 21 and the pressure tower-2 reboiler 23 respectively to realize the utilization of the heat from the top of the pressure distillation tower-4, and the material after heat exchange enters the pressure tower-1 reflux tank 49, and the liquid phase part of the pressure tower-1 reflux tank 49 is refluxed to the pressure distillation tower-4, and part is produced as refined methanol.

[0039] The atmospheric tower reboiler 25 is connected to the pressure tower 2 reflux device; the pressure tower 2 reflux device includes a pressure tower 2 reflux tank 55, and the atmospheric tower reboiler 2 output pipeline 62 at the output end of the atmospheric tower reboiler 25 is connected to the pressure tower 2 reflux tank 55; the bottom of the pressure tower 2 reflux tank 55 is connected to the upper part of the pressure distillation tower 2 5 through the pressure tower 2 reflux pipeline 56 to improve the purity of refined methanol; a pressure tower 2 circulation pump 57 is provided on the pressure tower 2 reflux pipeline 56, and a pressure tower 2 refined methanol extraction pipeline 58 is connected to the pressure tower 2 reflux pipeline 56, and the pressure tower 2 refined methanol extraction pipeline 58 is connected to the refined methanol tank 48 for storing refined methanol; preferably, the pressure distillation tower 2 5 is connected to the pressure tower 2 reflux pipeline 56. The extraction pipeline 159 at the top of tower 2 is connected to the reflux tank 55 of pressure tower 2, and the extraction pipeline 159 at the top of pressure tower 2 is connected to the extraction pipeline 69 at the top of pressure tower 2; a condenser 60 at the top of pressure tower 2 is arranged on the extraction pipeline 159 at the top of pressure tower 2; part of the material extracted from the top of pressure distillation tower 25 is heat-exchanged with the reboiler 25 of atmospheric pressure tower to realize the utilization of the heat at the top of pressure distillation tower 25, part of it enters the reflux tank 55 of pressure tower 2 after condensation by the condenser 60 at the top of pressure tower 2, and the material after heat exchange with the reboiler 25 of atmospheric pressure tower passes into the reflux tank 55 of pressure tower 2, and the liquid phase part of the reflux tank 55 of pressure tower 2 is refluxed to pressure distillation tower 25, and part of it is extracted as refined methanol.

[0040] The top of the atmospheric distillation tower 2 is provided with an atmospheric tower reflux device, and the atmospheric tower reflux device includes an atmospheric tower reflux tank 61. The top of the atmospheric distillation tower 2 is connected to the atmospheric tower reflux tank 61 through an atmospheric tower top extraction pipeline 63. The atmospheric tower top extraction pipeline 63 is provided with an atmospheric tower top condenser 64. The bottom of the atmospheric tower reflux tank 61 is connected to the upper part of the atmospheric distillation tower 2 through an atmospheric tower reflux pipeline 65, so as to improve the purity of refined methanol. degree; an atmospheric tower extraction pump 66 is provided on the atmospheric tower reflux line 65, and an atmospheric tower refined methanol extraction line 67 is connected to the atmospheric tower reflux line 65; further, the atmospheric tower refined methanol extraction line 67 is connected to the refined methanol tank 48 for storing refined methanol; the material extracted from the top of the atmospheric distillation tower 2 enters the atmospheric tower reflux tank 61 after condensation, and the liquid phase of the atmospheric tower reflux tank 61 is partially refluxed to the atmospheric distillation tower 2, and part is extracted as refined methanol.

[0041] The refined methanol production pipeline 67 of the atmospheric pressure tower, the refined methanol production pipeline 47 of the medium pressure tower, the refined methanol production pipeline 54 of the pressure tower one, and the refined methanol production pipeline 58 of the pressure tower two can be mixed after entering the refined methanol production pipeline 68 first and then produced to the refined methanol tank 48, that is, the refined methanol production pipeline 68 is connected to the refined methanol tank 48, and the refined methanol production pipeline 67 of the atmospheric pressure tower, the refined methanol production pipeline 47 of the medium pressure tower, the refined methanol production pipeline 54 of the pressure tower one, and the refined methanol production pipeline 58 of the pressure tower two are respectively connected to the refined methanol production pipeline 68; they can also be produced separately and then mixed, and the technical personnel can choose according to the specific situation, and there is no specific limitation.

[0042] Through this embodiment, methanol with a concentration of >99.99% and an ethanol content of 10-100 ppm can be produced.

[0043] Embodiment three:

[0044] This embodiment provides a specific embodiment, specifically:

[0045] The crude methanol enters the crude methanol feed preheater 7 for preheating, and the crude methanol feed preheater 7 preheats the crude methanol to about 100°C. The preheated crude methanol enters the pre-distillation tower 1 for distillation. The top pressure of the pre-distillation tower 1 is 170KPa, the top temperature is 81°C, and the bottom temperature is 83°C; the gas phase extracted from the top of the pre-distillation tower 1 goes to the atmospheric pressure tower reboiler 24 to provide part of the heat required for distillation to the atmospheric pressure distillation tower 2, and the material after heat exchange enters the pre-tower buffer tank and the pre-tower top reflux tank 33. The liquid phase in the pre-tower buffer tank and the pre-tower top reflux tank 33 is pressurized by the pre-tower reflux pump 36 and sent to the top of the pre-distillation tower 1 as reflux feed; the pre-tower buffer tank The gas phase of the pre-tower top reflux tank 33 is cooled by the pre-tower top reflux tank condenser 42 and then enters the extraction tank 38. The non-condensable gas produced after extraction in the extraction tank 38 is discharged, and the liquid phase produced after extraction is refluxed to the pre-tower buffer tank and the pre-tower top reflux tank 33; the pre-distillation tower 1 provides the heat required for distillation of the pre-distillation tower 1 in the form of indirect heating by the pre-tower reboiler 20, and the heat source of the pre-tower reboiler 20 is the gas phase extracted from the top of the medium-pressure distillation tower 3; the pre-tower reboiler 32 is a start-up reboiler, and the heat source is steam. When the pre-distillation tower 1 is started, steam is used to heat the pre-tower reboiler 32, and the steam pressure used by the pre-tower reboiler 32 is 0.7Mpa;

[0046] The liquid phase extracted from the bottom of the pre-distillation tower 1 enters the atmospheric distillation tower 2 for distillation. The top pressure of the atmospheric distillation tower 2 is 105KPa, the top temperature is 65°C, and the bottom temperature is 72°C. The gas phase extracted from the top of the atmospheric distillation tower 2 enters the atmospheric tower reflux tank 61 after condensation by the atmospheric tower top condenser 64. The liquid phase of the atmospheric tower reflux tank 61 is pressurized by the atmospheric tower extraction pump 66 and is divided into two streams, one of which returns to the atmospheric distillation tower 2, that is, refluxes to the top of the atmospheric distillation tower 2 as reflux feed; the other stream extracts refined methanol; the atmospheric distillation tower 2 provides the heat required for distillation of the atmospheric distillation tower 2 in the form of indirect heating by the atmospheric tower reboiler-24 and the atmospheric tower reboiler-25, wherein the heat source of the atmospheric tower reboiler-24 is the gas phase extracted from the top of the pre-distillation tower 1, and the heat source of the atmospheric tower reboiler-25 is the gas phase extracted from the top of the pressurized distillation tower-5;

[0047] The bottom liquid of the atmospheric distillation tower 2 enters the medium-pressure distillation tower 3 through the atmospheric tower bottom pump 10 to continue distillation. The top pressure of the medium-pressure distillation tower 3 is 300KPa, the top temperature is 94°C, and the bottom temperature is 105°C. The gas phase extracted from the top of the medium-pressure distillation tower 3 goes to the pre-tower reboiler 20 to provide the heat required for distillation for the pre-distillation tower 1, and enters the medium-pressure tower reflux tank 43 after heat exchange. The liquid phase in the medium-pressure tower reflux tank 43 is pressurized by the medium-pressure tower extraction pump 46 and is divided into two streams, one of which refluxes to the medium-pressure distillation tower 3, that is, flows into the top of the medium-pressure distillation tower 3 as reflux feed; one extracts refined methanol; the medium-pressure distillation tower 3 provides the heat required for distillation of the medium-pressure distillation tower 3 in the form of indirect heating by the medium-pressure tower reboiler 21, and the heat source of the medium-pressure tower reboiler 21 is the gas phase extracted from the top of the pressurized distillation tower-4;

[0048] The bottom liquid of the medium-pressure distillation tower 3 enters the pressure distillation tower 4 through the medium-pressure tower bottom pump 12 to continue distillation. The top pressure of the pressure distillation tower 4 is 800KPa, the top temperature is 128°C, and the bottom temperature is 142°C. The gas phase extracted from the top of the pressure distillation tower 4 is divided into two streams. One stream goes to the reboiler 23 of the pressure distillation tower 2 to provide the heat required for distillation for the pressure distillation tower 2 5, and enters the reflux tank 49 of the pressure tower 1 after heat exchange; the other stream goes to the reboiler 21 of the medium-pressure tower to provide the heat required for distillation for the medium-pressure distillation tower 3 , after heat exchange, it enters the pressure tower-reflux tank 49; the liquid phase in the pressure tower-reflux tank 49 is pressurized by the pressure tower-reflux pump 53 and is divided into two streams, one stream refluxes to the pressure distillation tower-4, that is, flows into the top of the pressure distillation tower-4 as reflux feed; one stream produces refined methanol; the pressure distillation tower-4 provides the heat required for the distillation pressure distillation tower in the form of indirect heating by the pressure tower-reboiler 22, the heat source of the pressure tower-reboiler 22 is steam, and the steam pressure used by the pressure tower-reboiler 22 is 0.7Mpa;

[0049] The bottom liquid of the pressure distillation tower 1 4 enters the pressure distillation tower 2 5 for further distillation. The top pressure of the pressure distillation tower 2 5 is 175KPa, the top temperature is 79°C, and the bottom temperature is 117°C. The gas phase at the top of the pressure distillation tower 2 5 goes to the atmospheric tower reboiler 2 25 to provide part of the heat required for distillation for the atmospheric distillation tower 2, and then enters the pressure tower 2 reflux tank 55 after heat exchange. The liquid phase in the pressure tower 2 reflux tank 55 passes through the pressure tower 2 After pressurization by the circulating pump 57, it is divided into two streams, one of which refluxes to the pressurized distillation tower 25, that is, enters the upper part of the pressurized distillation tower 25 as reflux feed; the other produces refined methanol; the pressurized distillation tower 25 provides the heat required for distillation of the pressurized distillation tower 25 through indirect heating by the pressurized distillation tower 2 reboiler 23, and the heat source of the pressurized distillation tower 2 reboiler 23 is the gas phase at the top of the pressurized distillation tower 14; the side line of the pressurized distillation tower 25 produces fusel alcohol, and the bottom of the tower produces waste water.

[0050] In this embodiment, the pre-tower reboiler 32 and the pressure tower reboiler 22 use steam heat source, the methanol vapor at the top of the pressure distillation tower 4 provides heat to the medium-pressure tower reboiler 21 and the pressure tower 2 reboiler 23; the methanol vapor at the top of the pressure distillation tower 25 provides heat to the atmospheric pressure tower reboiler 25, and the steam at the top of the pre-distillation tower 1 supplements the remaining heat of the atmospheric pressure tower reboiler 24. The energy consumption per ton of refined methanol is about 0.53t of steam.

[0051] Embodiment 4:

[0052] This embodiment provides a specific application scenario, specifically:

[0053] In a methanol plant, a crude methanol refining and recovery device with an annual output of 300,000 tons is used, with a crude methanol feed rate of 44,000 kg / h, of which the water content is 6.74%, and the ethanol content is about 600 ppm. When the process-related parameters are optimized to the best, through the five-tower thermal coupling process of the present application, the steam energy consumption of refined alcohol is about 0.53 tons of steam / refined methanol, of which the methanol purity can reach more than 99.99%, and the ethanol content is less than 50 ppm.

[0054] The process-related parameters for each tower operation are shown in the following table:

[0055]

[0056] The reboiler load of the pre-distillation tower 1 includes the overall load of the pre-tower reboiler 20 and the pre-tower reboiler 1 32, and the reboiler load of the atmospheric distillation tower 2 includes the overall load of the atmospheric tower reboiler 1 24 and the atmospheric tower reboiler 2 25.

[0057] For traditional double-effect distillation units, the process capacity expansion can reach more than 50%, while reducing steam consumption by 50%-55%; for new markets, the investment is small, the operability is strong, and the use of heat exchange networks to optimize heat recovery and other energy-saving measures greatly reduces steam consumption, so that the consumption per ton of methanol can be reduced to less than 0.60 tons of steam / ton of refined methanol.

[0058] In summary, due to the adoption of the above technical scheme, the present application adopts a five-tower device of a pre-distillation tower, an atmospheric distillation tower, a medium-pressure distillation tower, a pressurized distillation tower 1, and a pressurized distillation tower 2. Compared with the traditional three-tower device, a medium-pressure distillation tower and a pressurized distillation tower 2 are added, and a five-tower thermal coupling device is adopted to optimize the heat exchange network and improve energy saving space; the top steam of the original pressurized distillation tower 1 is used to provide heat for the newly added medium-pressure distillation tower and the pressurized distillation tower 2, and at the same time, the top steam of the newly added medium-pressure distillation tower is used to provide heat for the pre-distillation tower. The top steam of the pre-distillation tower and the newly added pressurized distillation tower 2 provides heat for the atmospheric distillation tower, making full use of the heat at the top of each distillation tower; through this application, the traditional equipment can be transformed, and the unit consumption of the methanol distillation process can be reduced from 1.2t steam / t refined alcohol to 0.50-0.60t steam / t refined alcohol, achieving a significant reduction in energy consumption, greatly reducing operating costs for the enterprise and improving the competitiveness of the enterprise; and the application does not require a vacuum pump for the utilization of heat, and has better safety.

[0059] The above-mentioned devices, connection relationships, etc. that are not specifically described belong to the prior art and will not be described in detail in the present utility model.

[0060] The preferred embodiments of the present application are described in detail above in conjunction with the accompanying drawings; however, the present application is not limited to the specific details in the above embodiments. Within the technical concept of the present application, a variety of simple modifications can be made to the technical solution of the present application, and these simple modifications all fall within the protection scope of the present application.

[0061] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the various possible combinations of this application will not be described separately.

[0062] In addition, the various implementation modes of the present application may be arbitrarily combined, and as long as they do not violate the concept of the present application, they should also be regarded as the contents disclosed in the present application.

Claims

1. A five-tower thermally coupled crude methanol refining device, comprising a pre-distillation tower (1), an atmospheric distillation tower (2), and a pressure distillation tower (4), characterized in that: A medium-pressure distillation tower (3) is arranged between the atmospheric distillation tower (2) and the pressure distillation tower one (4); a pressure distillation tower two (5) is arranged at the rear of the pressure distillation tower one (4); a pre-tower reboiler (20), a medium-pressure tower reboiler (21), a pressure tower one reboiler (22), and a pressure tower two reboiler (23) are arranged at the lower parts of the pre-distillation tower (1), the medium-pressure distillation tower (3), the pressure distillation tower one (4), and the pressure distillation tower two (5), respectively; an atmospheric distillation tower (2) is arranged at the lower part of the atmospheric distillation tower (2) with an atmospheric tower reboiler one (24) and an atmospheric tower reboiler two (25); The top of the distillation tower (1) is connected to the atmospheric pressure tower reboiler 1 (24) through a pre-tower top extraction pipeline (26), the top of the medium-pressure distillation tower (3) is connected to the pre-tower reboiler (20) through a medium-pressure tower top extraction pipeline (27), the top of the pressurized distillation tower 1 (4) is connected to the medium-pressure tower reboiler (21) and the pressurized tower 2 reboiler (23) through a pressurized tower 1 top extraction pipeline 1 (28) and a pressurized tower 1 top extraction pipeline 2 (29), respectively, and the top of the pressurized distillation tower 2 (5) is connected to the atmospheric pressure tower reboiler 2 (25) through a pressurized tower 2 top extraction pipeline (69).

2. A crude methanol five-tower thermally coupled refining device according to claim 1, characterized in that: The atmospheric tower reboiler 1 (24) is connected to the pre-tower reflux device.

3. A crude methanol five-tower thermally coupled refining device according to claim 2, characterized in that: The pre-tower reflux device comprises a pre-tower top reflux tank (33), the bottom of which is connected to the upper part of the pre-distillation tower (1) via a pre-tower reflux pipeline (35), the pre-tower top reflux tank (33) is connected to the bottom of an extraction tank (38) via a pipeline 1 (37), an extraction water pipeline (39) is provided on one side of the extraction tank (38), and a purge gas pipeline (40) is provided on the top of the extraction tank (38); the pre-tower top reflux tank (33) is also connected to the upper part of the extraction tank (38) via a pipeline 2 (41), and a pre-tower top reflux tank condenser (42) is provided on the pipeline 2 (41).

4. A crude methanol five-tower thermally coupled refining device according to claim 1, characterized in that: The pre-tower reboiler (20) is connected to the medium-pressure tower reflux device.

5. A five-tower thermally coupled crude methanol refining device according to claim 4, characterized in that: The medium-pressure tower reflux device comprises a medium-pressure tower reflux tank (43), the bottom of which is connected to the upper part of the medium-pressure distillation tower (3) via a medium-pressure tower reflux pipeline (45), and the medium-pressure tower reflux pipeline (45) is connected to a medium-pressure tower refined methanol extraction pipeline (47).

6. A crude methanol five-tower thermally coupled refining device according to claim 1, characterized in that: The medium-pressure tower reboiler (21) and the pressure tower second reboiler (23) are respectively connected to the pressure tower first reflux device.

7. A five-tower thermally coupled crude methanol refining device according to claim 6, characterized in that: The pressurized tower-reflux device comprises a pressurized tower-reflux tank (49), the bottom of which is connected to the upper part of the pressurized distillation tower-1 (4) via a pressurized tower-reflux pipeline (52), and the pressurized tower-refined methanol extraction pipeline (54) is connected to the pressurized tower-reflux pipeline (52).

8. The crude methanol five-tower thermally coupled refining device according to claim 1, characterized in that: The atmospheric tower reboiler 2 (25) is connected to the pressure tower 2 reflux device.

9. A crude methanol five-tower thermally coupled refining device according to claim 8, characterized in that: The pressure tower 2 reflux device comprises a pressure tower 2 reflux tank (55), the bottom of which is connected to the upper part of the pressure distillation tower 2 (5) via a pressure tower 2 reflux pipeline (56), and the pressure tower 2 reflux pipeline (56) is connected to a pressure tower 2 refined methanol extraction pipeline (58).

10. A crude methanol five-tower thermally coupled refining device according to claim 9, characterized in that: The second pressurized distillation tower (5) is connected to the second pressurized tower reflux tank (55) via the second pressurized tower top extraction pipeline (59), and the second pressurized tower reflux tank (55) is provided with a second pressurized tower top condenser (60).

Images