Six-tower thermal coupling refining device for crude methanol

Abstract

The utility model provides a six-tower thermal coupling refining device for crude methanol, which comprises a pre-rectifying tower, a normal-pressure rectifying tower, a negative-pressure rectifying tower, a medium-pressure rectifying tower, a pressurized rectifying tower I and a pressurized rectifying tower II, the tower top of the pre-rectifying tower is connected with a normal-pressure tower reboiler I, and the tower top of the normal-pressure rectifying tower is connected with a negative-pressure tower reboiler; the top of the medium-pressure rectifying tower is connected with a pre-tower reboiler, the top of the pressurized rectifying tower I is respectively connected with a medium-pressure tower reboiler and a pressurized tower II reboiler, and the top of the pressurized rectifying tower II is connected with an atmospheric tower reboiler II; in the application, methanol steam at the top of a pressurized rectifying tower I provides heat for a medium-pressure rectifying tower and a pressurized rectifying tower II; methanol steam at the top of the medium-pressure rectifying tower provides heat for the pre-rectifying tower; top steam of the pre-rectifying tower and top methanol steam of the pressurized rectifying tower II provide heat for the normal-pressure rectifying tower; the tower top steam of the normal-pressure rectifying tower provides heat for the negative-pressure rectifying tower; the steam at each tower top is utilized, and the unit consumption of the methanol rectification process is 0.36-0.50 t steam / t refined alcohol.

Description

Technical Field

[0001] The present application relates to the field of chemical technology, and in particular to a six-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 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 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 consumption of the whole system high, about 1.2t steam / t refined alcohol. In the context of the country's increasingly stringent requirements on carbon emission indicators, 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, the six-tower reverse four-effect methanol distillation method with a pre-distillation tower as a heat source in the prior art with application number CN202110950292.5 discloses a technical solution, wherein the bottom of the pre-distillation tower is connected to the middle and lower part of the vacuum tower through a pipeline; the bottom of the vacuum tower is connected to the middle and lower part of the atmospheric tower through a pipeline; the bottom of the atmospheric tower is connected to the middle and lower part of the medium-pressure tower through a pipeline; the bottom of the medium-pressure tower is connected to the middle and lower part of the high-pressure tower through a pipeline; the side line extraction of the high-pressure tower is connected to the middle and lower part of the recovery tower through a pipeline. The core step is to use the pre-distillation tower as one of the heat sources, and use the top material steam of the pre-distillation tower and the top material steam of the atmospheric tower to supply heat to the vacuum tower until it is completely condensed; the top material steam of the medium-pressure tower supplies heat to the atmospheric tower until it is completely condensed; the top material steam of the high-pressure tower supplies heat to the medium-pressure tower until it is completely condensed; this application achieves a significant energy-saving effect in the methanol distillation process. At the same time, the present application also proposes an improved six-tower reverse four-effect methanol distillation process with a pre-distillation tower as a heat source, providing a new energy-saving option for methanol distillation; the application discloses the idea of ​​six towers, but the methanol distillation process unit consumption of the application is 0.6-0.7 steam / t of refined alcohol, which is lower than the traditional process, but the remaining schemes can still achieve a lower methanol distillation process unit consumption, and the tower configuration and heat supply method in the application are different from the idea of ​​the present application.

[0005] In summary, it is necessary to provide a new technical solution to solve the above technical problems. Utility Model Content

[0006] The present application provides a six-tower thermal coupling refining device for crude methanol, including a pre-distillation tower, wherein the pre-distillation tower is connected to an atmospheric distillation tower and a negative pressure distillation tower respectively, wherein the atmospheric distillation tower and the negative pressure distillation tower are connected to a medium pressure distillation tower respectively, wherein a pressure distillation tower 1 and a pressure distillation tower 2 are sequentially arranged at the rear of the medium pressure distillation tower, wherein a pre-tower reboiler, a negative pressure tower reboiler, a medium pressure tower reboiler, a pressure tower 1 reboiler and a pressure tower 2 reboiler are respectively arranged at the lower parts of the pre-distillation tower, the negative pressure distillation tower, the medium pressure distillation tower, the pressure distillation tower 1 and the pressure distillation tower 2, wherein a reboiler of a pre-tower, a negative pressure tower reboiler, a medium pressure tower reboiler, a pressure tower 1 reboiler and a pressure tower 2 reboiler are arranged at the lower part of the atmospheric pressure distillation tower 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 atmospheric distillation tower is connected to the negative pressure tower reboiler through the atmospheric pressure 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.

[0007] 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.

[0008] As a preferred solution, the atmospheric tower reboiler is connected to the pre-tower reflux device.

[0009] 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.

[0010] As a preferred solution, the negative pressure tower reboiler is connected to the atmospheric pressure tower reflux device.

[0011] As a preferred embodiment, the atmospheric tower reflux device includes an atmospheric tower reflux tank, the bottom of which is connected to the upper part of the atmospheric distillation tower through an atmospheric tower reflux pipeline, and the atmospheric tower reflux pipeline is connected to an atmospheric tower refined methanol extraction pipeline.

[0012] As a preferred solution, the refined methanol production pipeline of the atmospheric tower is connected to the refined methanol tank.

[0013] As a preferred solution, the atmospheric distillation tower is connected to the atmospheric tower reflux tank via an atmospheric tower top extraction pipeline 1, and an atmospheric tower top condenser is provided on the atmospheric tower top extraction pipeline 1.

[0014] As a preferred solution, the pre-tower reboiler is connected to the medium-pressure tower reflux device.

[0015] 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.

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

[0017] 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.

[0018] 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.

[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 solution, the atmospheric tower reboiler 2 is connected to the pressure tower 2 reflux device.

[0021] 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.

[0022] As a preferred solution, the refined methanol production pipeline of the pressure tower is connected to the refined methanol tank.

[0023] 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.

[0024] As a preferred solution, a negative pressure tower reflux device is provided on the top of the negative pressure distillation tower.

[0025] As a preferred embodiment, the negative pressure tower reflux device includes a negative pressure tower reflux tank, the top of the negative pressure distillation tower is connected to the negative pressure tower reflux tank through a negative pressure tower top extraction pipeline, a negative pressure tower top condenser is arranged on the negative pressure tower top extraction pipeline, the bottom of the negative pressure distillation tower is connected to the negative pressure distillation tower through a negative pressure tower reflux pipeline, and a negative pressure tower refined methanol extraction pipeline is connected to the negative pressure tower reflux pipeline.

[0026] As a preferred solution, the refined methanol extraction pipeline of the negative pressure tower is connected to the refined methanol tank.

[0027] As a preferred solution, the top of the negative pressure tower reflux tank is connected to the absorption tower through an absorption tower connecting pipeline, the top of the absorption tower is provided with an absorption tower top extraction pipeline, and the absorption tower top extraction pipeline is provided with a vacuum pump; the bottom of the absorption tower is connected to the negative pressure distillation tower through an absorption tower reflux pipeline.

[0028] The present application adopts a six-tower equipment, including a pre-distillation tower, an atmospheric distillation tower, a negative pressure distillation tower, a medium-pressure distillation tower, a pressurized distillation tower one and a pressurized distillation tower two, wherein the methanol vapor at the top of the pressurized distillation tower one provides heat for the medium-pressure distillation tower and the pressurized distillation tower two, thereby realizing thermal coupling; the methanol vapor at the top of the medium-pressure distillation tower provides heat for the pre-distillation tower, thereby realizing thermal coupling; the vapor at the top of the pre-distillation tower and the methanol vapor at the top of the pressurized distillation tower two provide heat for the atmospheric distillation tower, thereby realizing thermal coupling; the vapor at the top of the atmospheric distillation tower provides heat for the negative pressure distillation tower, thereby realizing thermal coupling; through the thermal coupling of the present application, the steam at the top of each tower is fully utilized, and the unit consumption of the methanol distillation process can be reduced from 1.2t steam / t refined alcohol to 0.36-0.50t steam / t refined alcohol, which can save more than half of the energy compared with the traditional double-tower thermal coupling process, thereby greatly reducing the operating cost for the enterprise and improving the competitiveness of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of this application;

[0030] 1. Pre-distillation tower; 2. Atmospheric distillation tower; 3. Negative pressure distillation tower; 4. Medium pressure distillation tower; 5. Pressure distillation tower 1; 6. Pressure distillation tower 2; 7. Feed pipeline; 8. Crude methanol feed preheater; 9. Pre-tower kettle extraction pipeline; 10. Divider; 11. Pre-tower kettle extraction pipeline 1; 12. Pre-tower kettle extraction pipeline 2; 13. Atmospheric pressure tower kettle extraction pipeline; 1 4. Negative pressure tower kettle extraction pipeline; 15. Mixer; 16. Medium pressure tower connecting pipeline; 17. Negative pressure tower kettle pump; 18. Kettle pump; 19. Medium pressure tower kettle extraction pipeline; 20. Medium pressure tower kettle pump; 21. Pressure tower kettle extraction pipeline for pressure tower 1; 22. Pressure tower kettle extraction pipeline for pressure tower 2; 23. Pressure tower kettle pump for pressure tower 2; 24. Pressure tower side extraction pipeline; 25. Condenser; 26, buffer tank; 27, side production pump; 28, pre-tower reboiler; 29, negative pressure tower reboiler; 30, medium pressure tower reboiler; 31, pressure tower one reboiler; 32, pressure tower two reboiler; 33, atmospheric tower reboiler one; 34, atmospheric tower reboiler two; 35, pre-tower top production pipeline; 36, atmospheric tower top production pipeline; 37, medium pressure tower top production pipeline; 38, pressure tower one top production pipeline one; 39, pressure tower one top production pipeline two; 40, pressure tower two top production pipeline; 41, steam pipeline; 42, steam condensate production pipeline; 43, pre-tower reboiler one; 44, pre-tower top reflux tank; 45, atmospheric tower reboiler one output pipeline; 46, pre-tower reflux pipeline; 47, pre-tower reflux pump; 48 , pipeline one; 49, extraction tank; 50, extraction water pipeline; 51, purge gas pipeline; 52, pipeline two; 53, reflux tank condenser at the top of pre-tower; 54, reflux tank of medium-pressure tower; 55, output pipeline of reboiler of pre-tower; 56, reflux pipeline of medium-pressure tower; 57, extraction pump of medium-pressure tower; 58, extraction pipeline of refined methanol of medium-pressure tower; 59, refined methanol tank; 60, extraction pipeline one at the top of medium-pressure tower; 61, condenser of medium-pressure tower; 62, reflux tank of atmospheric tower; 63, output pipeline of reboiler of negative pressure tower; 64, reflux pipeline of atmospheric tower; 65, extraction pump of atmospheric tower; 66, extraction pipeline of refined methanol of atmospheric tower; 67, extraction pipeline one at the top of atmospheric tower; 68, condenser of atmospheric tower; 69, reflux tank of pressure tower one; 70, output pipeline of reboiler of medium-pressure tower; 7 1. Pressure tower 2 reboiler output pipeline; 72. Pressure tower 1 reflux pipeline; 73. Pressure tower 1 reflux pump; 74. Pressure tower 1 refined methanol extraction pipeline; 75. Pressure tower 1 top extraction pipeline 1; 76. Pressure tower 1 condenser; 77. Pressure tower 2 reflux tank; 78. Atmospheric tower reboiler 2 output pipeline; 79. Pressure tower 2 reflux pipeline; 80. Pressure tower 2 extraction pump; 81. Pressure tower 2 refined methanol extraction pipeline; 82. Pressure tower 2 top extraction pipeline 1; 83. Pressure tower 2 top condenser; 84. Negative pressure tower reflux tank; 85. Negative pressure tower top extraction pipeline; 86. Negative pressure tower top condenser; 87. Negative pressure tower reflux pipeline; 88. Negative pressure tower extraction pump; 89. Negative pressure tower refined methanol extraction pipeline; 90. Refined methanol extraction pipeline;91. Absorption tower connecting pipeline; 92. Absorption tower; 93. Absorption tower top extraction pipeline; 94. Vacuum pump; 95. Absorption tower reflux pipeline; 96. Water inlet pipeline. ; DETAILED DESCRIPTION

[0031] 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.

[0032] Embodiment 1:

[0033] The present application provides a six-tower thermal coupling refining device for crude methanol, comprising a pre-distillation tower 1, the pre-distillation tower 1 is respectively connected to an atmospheric distillation tower 2 and a negative pressure distillation tower 3, the atmospheric distillation tower 2 and the negative pressure distillation tower 3 are respectively connected to a medium pressure distillation tower 4, and a pressure distillation tower 1 5 and a pressure distillation tower 2 6 are sequentially arranged at the rear of the medium pressure distillation tower 4;

[0034] Preferably, the top pressure of the pre-distillation tower 1 is 150-220 kPa, the top pressure of the atmospheric distillation tower 2 is 100-150 kPa, the top pressure of the negative pressure distillation tower 3 connected in parallel with the atmospheric distillation tower 2 is 40-95 kPa, the top pressure of the medium pressure distillation tower 4 is 250-350 kPa, the top pressure of the pressure distillation tower 1 5 is 700-800 kPa, and the top pressure of the pressure distillation tower 2 6 is 150-280 kPa.

[0035] A feed pipeline 7 is provided on one side of the pre-distillation tower 1, and a crude methanol feed preheater 8 is provided on the feed pipeline 7, which is used to preheat the crude methanol material entering the pre-distillation tower 1 to improve the stability of distillation; a pre-tower reactor extraction pipeline 9 is provided at the bottom of the pre-distillation tower 1, and the pre-tower reactor extraction pipeline 9 is respectively connected to a pre-tower reactor extraction pipeline 11 and a pre-tower reactor extraction pipeline 2 12 through a splitter 10, wherein the pre-tower reactor extraction pipeline 1 11 is connected to the atmospheric distillation tower 2, and the pre-tower reactor extraction pipeline 2 12 is connected to the negative pressure distillation tower 3;

[0036] The bottom of the atmospheric distillation tower 2 is provided with an atmospheric tower reactor extraction pipeline 13, and the bottom of the negative pressure distillation tower 3 is provided with a negative pressure tower reactor extraction pipeline 14. The atmospheric tower reactor extraction pipeline 13 and the negative pressure tower reactor extraction pipeline 14 are connected to the medium-pressure tower connecting pipeline 16 through a mixer 15. The medium-pressure tower connecting pipeline 16 is connected to the medium-pressure distillation tower 4. The negative pressure tower reactor extraction pipeline 14 is provided with a negative pressure tower reactor pump 17, and the medium-pressure tower connecting pipeline 16 is provided with a tower reactor pump 18; the bottom of the medium-pressure distillation tower 4 is connected to the pressurized distillation tower 5 through a medium-pressure tower reactor extraction pipeline 19, and the medium-pressure tower reactor extraction pipeline 1 9 is provided with a medium-pressure tower kettle pump 20; the bottom of the pressurized distillation tower 1 5 is connected to the pressurized distillation tower 2 6 through the pressurized tower 1 kettle extraction pipeline 21, the bottom of the pressurized distillation tower 2 6 is provided with a pressurized tower 2 kettle extraction pipeline 22 for extracting waste water, and the pressurized tower 2 kettle extraction pipeline 22 is provided with a pressurized tower 2 kettle pump 23; a pressurized tower 2 side extraction pipeline 24 is provided on one side of the pressurized distillation tower 2 6, and the pressurized tower 2 side extraction pipeline 24 is used to extract fusel alcohol, and a condenser 25 is provided on the pressurized tower 2 side extraction pipeline 24, and a buffer tank 26 and a side extraction pump 27 are sequentially provided at the rear of the condenser 25;

[0037] The lower parts of the pre-distillation tower 1, the negative pressure distillation tower 3, the medium pressure distillation tower 4, the pressure distillation tower 1 5, and the pressure distillation tower 2 6 are respectively provided with a pre-tower reboiler 28, a negative pressure tower reboiler 29, a medium pressure tower reboiler 30, a pressure tower 1 reboiler 31, and a pressure tower 2 reboiler 32, and the lower part of the atmospheric distillation tower 2 is provided with an atmospheric pressure tower reboiler 1 33 and an atmospheric pressure tower reboiler 2 34;

[0038] The top of the pre-distillation tower 1 is connected to the atmospheric tower reboiler 33 through the pre-tower top extraction pipeline 35, the material extracted from the top of the pre-distillation tower 1 is heat-exchanged with the atmospheric tower reboiler 33, and the material after heat exchange 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 33, so as to provide the heat required for distillation for the atmospheric distillation tower 2, thereby improving the utilization rate of heat; the top of the atmospheric distillation tower 2 is connected to the negative pressure tower reboiler 29 through the atmospheric pressure tower top extraction pipeline 36, the material extracted from the top of the atmospheric distillation tower 2 is heat-exchanged with the negative pressure tower reboiler 29, and the material after heat exchange 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 33, thereby providing the heat required for distillation for the atmospheric distillation tower 2, thereby improving the utilization rate of heat; Reflux to the atmospheric distillation tower 2, and use the heat from the top of the atmospheric distillation tower 2 to heat the negative pressure tower reboiler 29, so as to provide the heat required for distillation for the negative pressure distillation tower 3, thereby improving the utilization rate of heat; the top of the medium-pressure distillation tower 4 is connected to the pre-tower reboiler 28 through the medium-pressure tower top extraction pipeline 37, and the material extracted from the top of the medium-pressure distillation tower 4 is heat-exchanged with the pre-tower reboiler 28, and the material after heat exchange refluxes to the medium-pressure distillation tower 4, and uses the heat from the top of the medium-pressure distillation tower 4 to heat the pre-tower reboiler 28, thereby providing the heat required for distillation for the pre-distillation tower 1, thereby improving the utilization rate of heat; the pressurized distillation tower The top of the pressure distillation tower 5 is connected to the medium-pressure tower reboiler 30 and the pressure tower 2 reboiler 32 through the pressure tower 1 top extraction pipeline 1 38 and the pressure tower 1 top extraction pipeline 2 39 respectively. The materials extracted from the top of the pressure distillation tower 5 are heat-exchanged with the medium-pressure tower reboiler 30 and the pressure tower 2 reboiler 32 respectively. The materials after heat exchange are refluxed to the pressure distillation tower 5. The heat from the top of the pressure distillation tower 5 is used to heat the medium-pressure tower reboiler 30 and the pressure tower 2 reboiler 32 respectively, so as to provide the heat required for distillation for the medium-pressure distillation tower 4 and the pressure distillation tower 2 6, thereby improving the utilization rate of heat. The top of the pressure distillation tower 2 6 The pressure tower 2 is connected to the atmospheric tower reboiler 2 34 through the extraction pipeline 40 at the top of the pressure tower 2; the material extracted from the top of the pressure distillation tower 2 6 is heat-exchanged with the atmospheric tower reboiler 2 34, and the heat-exchanged material is refluxed to the pressure distillation tower 2 6, and the heat at the top of the pressure distillation tower 2 6 is used to heat the atmospheric tower reboiler 2 34, so as to provide the atmospheric distillation tower 2 with the heat required for distillation, thereby improving the utilization rate of heat; the pressure tower 1 reboiler 31 is heated by steam, specifically, the input end of the pressure tower 1 reboiler 31 is connected to the steam pipeline 41, and the output end of the pressure tower 1 reboiler 31 is connected to the steam condensate extraction pipeline 42;

[0039] In order to provide the heat required for startup, a pre-tower reboiler 43 is further provided at the lower part of the pre-distillation tower 1, the input end of the pre-tower reboiler 43 is connected to the steam pipeline 41, and the output end of the pre-tower reboiler 43 is connected to the steam condensate extraction pipeline 42, so that the pre-distillation tower 1 is provided with the heat required for startup through steam. After the startup is stable, the steam heating can be turned off;

[0040] Preferably, in order to ensure the safety of the negative pressure distillation tower 3, minimize the methanol loss, and ensure a more stable vacuum degree, the top of the negative pressure tower reflux tank 84 is connected to the absorption tower 92 through an absorption tower connecting pipeline 91, and the top of the absorption tower 92 is provided with an absorption tower top production pipeline 93, and the absorption tower top production pipeline 93 is provided with a vacuum pump 94; the bottom of the absorption tower 92 is connected to the negative pressure distillation tower 3 through an absorption tower reflux pipeline 95; and a water inlet pipeline 96 is provided on one side of the absorption tower 92.

[0041] The present application adopts a six-tower equipment, including a pre-distillation tower 1, an atmospheric distillation tower 2, a negative pressure distillation tower 3, a medium-pressure distillation tower 4, a pressurized distillation tower 1 5 and a pressurized distillation tower 2 6, wherein the methanol vapor at the top of the pressurized distillation tower 1 5 provides heat for the medium-pressure distillation tower 4 and the pressurized distillation tower 2 6 to achieve thermal coupling; the methanol vapor at the top of the medium-pressure distillation tower 4 provides heat for the pre-distillation tower 1 to achieve thermal coupling; the top steam of the pre-distillation tower 1 and the top methanol vapor of the pressurized distillation tower 2 6 provide heat for the atmospheric distillation tower 2 to achieve thermal coupling; the top steam of the atmospheric distillation tower 2 provides heat for the negative pressure distillation tower 3 to achieve thermal coupling; through the thermal coupling of the present application, the steam at the top of each tower is fully utilized, and the unit consumption of the methanol distillation process can be reduced from 1.2t steam / t refined alcohol to 0.36-0.50t steam / t refined alcohol, which can save more than half of the energy compared with the traditional double-tower thermal coupling process, greatly reducing the operating cost for the enterprise and improving the competitiveness of the enterprise.

[0042] Embodiment 2:

[0043] In this embodiment, the pre-tower reflux device at the top of the pre-distillation tower 1, the negative pressure tower reflux device at the top of the negative pressure distillation tower 3, the atmospheric pressure 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 4, the pressure tower 1 reflux device at the top of the pressure distillation tower 5, and the pressure tower 2 reflux device at the top of the pressure distillation tower 2 6 are described, specifically:

[0044] The atmospheric tower reboiler 33 is connected to the pre-tower reflux device; the pre-tower reflux device includes a pre-tower top reflux tank 44, the atmospheric tower reboiler output pipeline 45 at the output end of the atmospheric tower reboiler 33 is connected to the pre-tower top reflux tank 44, the bottom of the pre-tower top reflux tank 44 is connected to the upper part of the pre-distillation tower 1 through a pre-tower reflux pipeline 46 for reflux, and a pre-tower reflux pump 47 is provided on the pre-tower reflux pipeline 46; the pre-tower top reflux tank 44 is connected to the bottom of the extraction tank 49 through a pipeline 48, an extraction water pipeline 50 is provided on one side of the extraction tank 49, and a purge gas pipeline 51 is provided on the top of the extraction tank 49; The pre-tower top reflux tank 44 is also connected to the upper part of the extraction tank 49 through a pipeline 2 52, and a pre-tower top reflux tank condenser 53 is provided on the pipeline 2 52; the material extracted from the top of the pre-distillation tower 1 is heat-exchanged with the atmospheric tower reboiler 1 33 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 44, and the liquid phase of the pre-tower top reflux tank 44 refluxes to the pre-distillation tower 1, and the non-condensable gas in the pre-tower top reflux tank 44 is cooled by the pre-tower top reflux tank condenser 53 and then enters the extraction tank 49, and the liquid phase of the extraction tank 49 flows into the pre-tower top reflux tank 44, and the non-condensable gas is extracted through the purge gas pipeline 51.

[0045] The pre-tower reboiler 28 is connected to the medium-pressure tower reflux device, and the medium-pressure tower reflux device includes a medium-pressure tower reflux tank 54. The pre-tower reboiler output pipeline 55 at the output end of the pre-tower reboiler 28 is connected to the medium-pressure tower reflux tank 54. The bottom of the medium-pressure tower reflux tank 54 is connected to the upper part of the medium-pressure distillation tower 4 through a medium-pressure tower reflux pipeline 56, which is used to increase the extraction concentration of refined methanol; a medium-pressure tower extraction pump 57 is provided on the medium-pressure tower reflux pipeline 56, and a medium-pressure tower refined methanol extraction pipeline 58 is connected to the medium-pressure tower reflux pipeline 56; further, the medium-pressure tower refined methanol extraction pipeline 58 is connected to a refined methanol tank 59 for storing refined methanol; The material taken out from the top of the distillation tower 4 is heat-exchanged with the pre-tower reboiler 28 to realize the utilization of the heat at the top of the medium-pressure distillation tower 4, and the material after heat exchange enters the medium-pressure tower reflux tank 54, and the liquid phase of the medium-pressure tower reflux tank 54 is partially refluxed to the medium-pressure distillation tower 4, and part of it is taken out as refined methanol; preferably, the top of the medium-pressure distillation tower 4 is also connected to the medium-pressure tower reflux tank 54 through a medium-pressure tower top production pipeline 60, and a medium-pressure tower condenser 61 is provided on the medium-pressure tower top production pipeline 60; part of the material at the top of the medium-pressure distillation tower 4 enters the medium-pressure tower reflux tank 54 after condensation, and part of it is heat-exchanged with the pre-tower reboiler 28.

[0046] The negative pressure tower reboiler 29 is connected to the atmospheric pressure tower reflux device; the atmospheric pressure tower reflux device includes an atmospheric pressure tower reflux tank 62, the negative pressure tower reboiler output pipeline 63 of the negative pressure tower reboiler 29 is connected to the atmospheric pressure tower reflux tank 62, the bottom of the atmospheric pressure tower reflux tank 62 is connected to the upper part of the atmospheric pressure distillation tower 2 through the atmospheric pressure tower reflux pipeline 64, which is used to increase the extraction concentration of refined methanol; the atmospheric pressure tower reflux pipeline 64 is provided with an atmospheric pressure tower extraction pump 65, and the atmospheric pressure tower reflux pipeline 64 is connected to the atmospheric pressure tower refined methanol extraction pipeline 66; the atmospheric pressure tower refined methanol extraction pipeline 66 is connected to the refined methanol tank 59 for storing refined methanol; the atmospheric pressure tower reflux pipeline 64 is provided with an atmospheric pressure tower extraction pump 65, and the atmospheric pressure tower reflux pipeline 64 is connected to the atmospheric pressure tower refined methanol extraction pipeline 66; the atmospheric pressure tower refined methanol extraction pipeline 66 is connected to the refined methanol tank 59 for storing refined methanol; The material taken out from the top of the distillation tower 2 is heat exchanged with the negative pressure tower reboiler 29 to realize the utilization of the heat at the top of the atmospheric distillation tower 2. The material after heat exchange enters the atmospheric pressure tower reflux tank 62, and the liquid phase of the atmospheric pressure tower reflux tank 62 is partially refluxed to the atmospheric pressure distillation tower 2, and part of it is taken out as refined methanol; preferably, the top of the atmospheric pressure distillation tower 2 is also connected to the atmospheric pressure tower reflux tank 62 through an atmospheric pressure tower top extraction pipeline 67, and an atmospheric pressure tower condenser 68 is provided on the atmospheric pressure tower top extraction pipeline 67; part of the material at the top of the atmospheric pressure distillation tower 2 enters the atmospheric pressure tower reflux tank 62 after condensation, and part of it is heat exchanged with the negative pressure tower reboiler 29.

[0047] The medium-pressure tower reboiler 30 and the pressure tower second reboiler 32 are respectively connected to the pressure tower one reflux device; the pressure tower one reflux device includes a pressure tower one reflux tank 69, and the output ends of the medium-pressure tower reboiler 30 and the pressure tower two reboiler 32 are respectively connected to the pressure tower one reflux tank 69 through the medium-pressure tower reboiler output pipeline 70 and the pressure tower two reboiler output pipeline 71; the bottom of the pressure tower one reflux tank 69 is connected to the upper part of the pressure distillation tower one 5 through the pressure tower one reflux pipeline 72, so as to improve the extraction concentration of refined methanol; a pressure tower one reflux pump 73 is arranged on the pressure tower one reflux pipeline 72, and a pressure tower one refined methanol extraction pipeline 74 is connected to the pressure tower one reflux pipeline 72, and the pressure tower one refined methanol extraction pipeline 74 is connected to the refined methanol tank 59, so as to improve the extraction concentration of refined methanol; for storing refined methanol; the material taken out from the top of the pressurized distillation tower-5 is respectively heat-exchanged with the medium-pressure tower reboiler 30 and the pressurized tower second reboiler 32 to realize the utilization of the heat from the top of the pressurized distillation tower-5, and the material after heat exchange enters the pressurized tower-one reflux tank 69, and the liquid phase part of the pressurized tower-one reflux tank 69 is refluxed to the pressurized distillation tower-5, and part of it is taken out as refined methanol; preferably, the top of the pressurized distillation tower-5 is also connected to the atmospheric pressure tower reflux tank 62 through the pressurized tower-top extraction pipeline-75, and the pressurized tower-top extraction pipeline-75 is provided with a pressurized tower-condenser 76; part of the material from the top of the pressurized distillation tower-5 enters the pressurized tower-one reflux tank 69 after condensation, and part of it is heat-exchanged with the medium-pressure tower reboiler 30 and the pressurized tower second reboiler 32.

[0048] The atmospheric tower reboiler 2 34 is connected to the pressure tower 2 reflux device; the pressure tower 2 reflux device includes a pressure tower 2 reflux tank 77, and the atmospheric tower reboiler 2 output pipeline 78 at the output end of the atmospheric tower reboiler 2 34 is connected to the pressure tower 2 reflux tank 77; the bottom of the pressure tower 2 reflux tank 77 is connected to the upper part of the pressurized distillation tower 2 6 through the pressurized tower 2 reflux pipeline 79 to improve the purity of refined methanol; a pressurized tower 2 extraction pump 80 is provided on the pressurized tower 2 reflux pipeline 79, and a pressurized tower 2 refined methanol extraction pipeline 81 is connected to the pressurized tower 2 reflux pipeline 79, and the pressurized tower 2 refined methanol extraction pipeline 81 is connected to the refined methanol tank 59 for storing refined methanol; preferably, the pressurized distillation tower 2 6 is connected to the pressurized tower 2 reflux pipeline 79. The extraction pipeline 82 at the top of tower two is connected to the reflux tank 77 of pressure tower two, and the extraction pipeline 82 at the top of pressure tower two is connected to the extraction pipeline 40 at the top of pressure tower two; a condenser 83 at the top of pressure tower two is arranged on the extraction pipeline 82 at the top of pressure tower two; part of the material extracted from the top of pressure distillation tower two 6 is heat-exchanged with the reboiler two 34 of atmospheric pressure tower to realize the utilization of the heat at the top of pressure distillation tower two 6, part of it enters the reflux tank 77 of pressure tower two after condensation by the condenser 83 at the top of pressure tower two, and the material after heat exchange with the reboiler two 34 of atmospheric pressure tower passes into the reflux tank 77 of pressure tower two, and the liquid phase part of the reflux tank 77 of pressure tower two flows back to pressure distillation tower two 6, and part of it is extracted as refined methanol.

[0049] The top of the negative pressure distillation tower 3 is provided with a negative pressure tower reflux device, and the negative pressure tower reflux device includes a negative pressure tower reflux tank 84. The top of the negative pressure distillation tower 3 is connected to the negative pressure tower reflux tank 84 through a negative pressure tower top extraction pipeline 85. A negative pressure tower top condenser 86 is provided on the negative pressure tower top extraction pipeline 85. The bottom of the negative pressure tower reflux tank 84 is connected to the upper part of the negative pressure distillation tower 3 through a negative pressure tower reflux pipeline 87, so as to improve the purity of refined methanol. degree; a negative pressure tower extraction pump 88 is provided on the negative pressure tower reflux pipeline 87, and a negative pressure tower refined methanol extraction pipeline 89 is connected to the negative pressure tower reflux pipeline 87; further, the negative pressure tower refined methanol extraction pipeline 89 is connected to the refined methanol tank 59 for storing refined methanol; the material extracted from the top of the negative pressure distillation tower 3 enters the negative pressure tower reflux tank 84 after condensation, and the liquid phase part of the negative pressure tower reflux tank 84 is refluxed to the negative pressure distillation tower 3, and part is extracted as refined methanol.

[0050] The refined methanol extraction pipeline 66 of the atmospheric pressure tower, the refined methanol extraction pipeline 58 of the medium pressure tower, the refined methanol extraction pipeline 89 of the negative pressure tower, the refined methanol extraction pipeline 74 of the pressure tower one, and the refined methanol extraction pipeline 81 of the pressure tower two can all be mixed after entering the refined methanol extraction pipeline 90 and then extracted to the refined methanol tank 59, that is, the refined methanol extraction pipeline 90 is connected to the refined methanol tank 59, and the refined methanol extraction pipeline 66 of the atmospheric pressure tower, the refined methanol extraction pipeline 58 of the medium pressure tower, the refined methanol extraction pipeline 89 of the negative pressure tower, the refined methanol extraction pipeline 74 of the pressure tower one, and the refined methanol extraction pipeline 81 of the pressure tower two are respectively connected to the refined methanol extraction pipeline 90; they can also be extracted separately and then mixed, and the technical personnel can choose according to the specific situation, and there is no specific limitation.

[0051] Through this embodiment, methanol with a concentration of >99.99% and an ethanol content of 10-100 ppm can be produced.

[0052] Embodiment three:

[0053] This embodiment provides a specific embodiment, specifically:

[0054] The crude methanol enters the crude methanol feed preheater 8 for preheating. The crude methanol feed preheater 8 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.

[0055] The gas phase extracted from the top of the pre-distillation tower 1 goes to the atmospheric tower reboiler 33 to provide the atmospheric distillation tower 2 with the heat required for distillation. The material after heat exchange enters the pre-tower top reflux tank 44. The liquid phase in the pre-tower top reflux tank 44 is pressurized by the pre-tower reflux pump 47 and sent to the top of the pre-distillation tower 1 as reflux feed; the gas phase in the pre-tower top reflux tank 44 is cooled by the pre-tower top reflux tank condenser 53 and then enters the extraction tank 49. The unsaturated gas generated after extraction in the extraction tank 49 The condensed gas is discharged, and the liquid phase produced after extraction is refluxed to the reflux tank 44 at the top of the pre-tower; the pre-distillation tower 1 provides the heat required for distillation of the pre-distillation tower 1 through indirect heating of the pre-tower reboiler 28 and the pre-tower reboiler 43, wherein the heat source of the pre-tower reboiler 43 is steam, and the steam heats the pre-tower reboiler 43; the heat source of the pre-tower reboiler 28 is the gas phase extracted from the top of the medium-pressure distillation tower 4; the steam pressure used by the pre-tower reboiler 43 is 0.7Mpa;

[0056] The liquid phase extracted from the bottom of the pre-distillation tower 1 passes through the splitter 10 and enters the atmospheric distillation tower 2 for distillation, and the other part enters the negative pressure distillation tower 3 for distillation; wherein, 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 62 after condensation, and the other part goes to the negative pressure tower reboiler 29 to provide the negative pressure distillation tower 3 with the heat required for distillation; the material after heat exchange enters the atmospheric tower reflux tank 62, and the liquid phase in the atmospheric tower reflux tank 62 is pressurized by the atmospheric tower extraction pump 65, and the other part is sent to the top of the atmospheric distillation tower 2 as reflux feed, and the other part is extracted as refined methanol; the atmospheric distillation tower 2 passes through the atmospheric tower reboiler 33 The heat required for distillation of the atmospheric distillation tower 2 is provided in the form of indirect heating with the atmospheric tower reboiler 234, wherein the heat source of the atmospheric tower reboiler 33 is the gas phase extracted from the top of the pre-distillation tower 1, and the heat source of the atmospheric tower reboiler 234 is the gas phase extracted from the top of the pressurized distillation tower 26; the top pressure of the negative pressure distillation tower 3 is 60KPa, the top temperature is 51°C, and the bottom temperature is 66°C. After condensation, part of the gas phase at the top of the negative pressure distillation tower 3 is refluxed to the negative pressure distillation tower 3, and part is extracted as refined methanol; the negative pressure distillation tower 3 provides the heat required for distillation of the negative pressure distillation tower 3 in the form of indirect heating by the negative pressure tower reboiler 29, wherein the heat source of the normal negative pressure tower reboiler 29 is the gas phase extracted from the top of the atmospheric distillation tower 2;

[0057] The bottom liquid of the atmospheric distillation tower 2 and the bottom liquid of the negative pressure distillation tower 3 pass through the mixer 15 and enter the medium-pressure distillation tower 4 to continue distillation. The top pressure of the medium-pressure distillation tower 4 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 4 goes to the pre-tower reboiler 28 to provide the heat required for distillation for the pre-distillation tower 1, and then enters the medium-pressure tower reflux tank 54 after heat exchange. The liquid phase in the medium-pressure tower reflux tank 54 is pressurized by the medium-pressure tower extraction pump 57 and is divided into two streams, one of which refluxes to the medium-pressure distillation tower 4, that is, flows into the top of the medium-pressure distillation tower 4 as reflux feed, and the other is used as refined methanol to extract refined methanol; the medium-pressure distillation tower 4 provides the heat required for distillation of the medium-pressure distillation tower 4 in the form of indirect heating by the medium-pressure tower reboiler 30, and the heat source of the medium-pressure tower reboiler 30 is the gas phase extracted from the top of the pressurized distillation tower-5;

[0058] The bottom liquid of the medium-pressure distillation tower 4 enters the pressure distillation tower 5 through the medium-pressure tower bottom pump 20 to continue distillation. The top pressure of the pressure distillation tower 5 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 5 is divided into two streams. One stream goes to the reboiler 32 of the pressure distillation tower 2 to provide the heat required for distillation for the pressure distillation tower 2 6, and enters the reflux tank 69 of the pressure tower 1 after heat exchange; the other stream goes to the reboiler 30 of the medium-pressure tower to provide the heat required for distillation for the medium-pressure distillation tower 4 , after heat exchange, it enters the pressure tower-reflux tank 69; the liquid phase in the pressure tower-reflux tank 69 is pressurized by the pressure tower-reflux pump 73 and is divided into two streams, one stream refluxes to the pressure distillation tower-5, that is, flows into the top of the pressure distillation tower-5 as reflux feed; one stream produces refined methanol; the pressure distillation tower-5 provides the heat required for the distillation pressure distillation tower in the form of indirect heating by the pressure tower-reboiler 31, the heat source of the pressure tower-reboiler 31 is steam, and the steam pressure used by the pressure tower-reboiler 31 is 0.7Mpa;

[0059] The bottom liquid of the pressure distillation tower 1 5 enters the pressure distillation tower 2 6 for further distillation. The top pressure of the pressure distillation tower 2 6 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 6 goes to the atmospheric tower reboiler 2 34 to provide part of the heat required for distillation for the atmospheric distillation tower 2, and then enters the pressure tower 2 reflux tank 77 after heat exchange. The liquid phase in the pressure tower 2 reflux tank 77 passes through the pressure tower 2 The extraction pump 80 is pressurized and divided into two streams, one of which refluxes to the pressurized distillation tower 2 6, that is, enters the upper part of the pressurized distillation tower 2 6 as reflux feed; the other extracts refined methanol; the pressurized distillation tower 2 6 provides the heat required for distillation of the pressurized distillation tower 2 6 through indirect heating of the pressurized distillation tower 2 reboiler 32, and the heat source of the pressurized distillation tower 2 reboiler 32 is the gas phase at the top of the pressurized distillation tower 1 5; the side line of the pressurized distillation tower 2 6 extracts fusel alcohol, and the bottom of the tower extracts waste water.

[0060] In this embodiment, the pre-tower reboiler 43 and the pressure tower reboiler 31 use steam heat source, the methanol vapor at the top of the pressure distillation tower 5 provides heat to the medium-pressure tower reboiler 30 and the pressure tower reboiler 2 32, the methanol vapor at the top of the pressure distillation tower 26 provides heat to the atmospheric pressure tower reboiler 2 34, the methanol vapor at the top of the atmospheric pressure distillation tower 2 provides heat to the negative pressure tower reboiler 29, and the steam at the top of the pre-distillation tower 1 supplements the remaining heat of the atmospheric pressure tower reboiler 33. In this embodiment, the energy consumption per ton of refined methanol is about 0.37 tons of steam.

[0061] Embodiment 4:

[0062] This embodiment provides a specific application scenario, specifically:

[0063] In a methanol plant, the crude methanol refining and recovery device with an annual output of 300,000 tons of crude methanol is used. The crude methanol feed rate is 44,000 kg / h, wherein the water content is 6.74%, and the ethanol content is about 600 ppm. The crude methanol is preheated to 100° C. by the crude methanol feed preheater 8 and then enters the pre-distillation tower 1. The operating parameters of each tower are shown in Table 1 below:

[0064]

[0065]

[0066] The reboiler load of the pre-distillation tower 1 includes the overall load of the pre-tower reboiler 28 and the pre-tower reboiler 43, and the reboiler load of the atmospheric distillation tower 2 includes the overall load of the atmospheric tower reboiler 33 and the atmospheric tower reboiler 34.

[0067] For traditional double-effect distillation units, the process capacity expansion can reach more than 60%, while reducing steam consumption by 60%-75%; 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 0.40 tons of steam / ton of refined methanol.

[0068] Through the six-tower thermal coupling process of the present application, the methanol purity can reach more than 99.99%, and the ethanol content is less than 50 ppm.

[0069] To sum up, due to the adoption of the above-mentioned technical scheme, the present application adopts a six-tower equipment, including a pre-distillation tower, an atmospheric distillation tower, a negative pressure distillation tower, a medium-pressure distillation tower, a pressurized distillation tower one and a pressurized distillation tower two, wherein the methanol vapor at the top of the pressurized distillation tower one provides heat for the medium-pressure distillation tower and the pressurized distillation tower two to achieve thermal coupling; the methanol vapor at the top of the medium-pressure distillation tower provides heat for the pre-distillation tower to achieve thermal coupling; the steam at the top of the pre-distillation tower and the methanol vapor at the top of the pressurized distillation tower two provide heat for the atmospheric distillation tower to achieve thermal coupling; the steam at the top of the atmospheric distillation tower provides heat for the negative pressure distillation tower to achieve thermal coupling; through the thermal coupling of the present application, the steam at the top of each tower is fully utilized, and the unit consumption of the methanol distillation process can be reduced from 1.2t steam / t refined alcohol to 0.36-0.50t steam / t refined alcohol, which can save more than half of the energy compared with the traditional double-tower thermal coupling process, greatly reducing the operating cost for the enterprise and improving the competitiveness of the enterprise.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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 six-tower thermally coupled crude methanol refining device, comprising a pre-distillation tower (1), characterized in that: The pre-distillation tower (1) is connected to the atmospheric distillation tower (2) and the negative pressure distillation tower (3), respectively. The atmospheric distillation tower (2) and the negative pressure distillation tower (3) are connected to the medium pressure distillation tower (4), respectively. The rear of the medium pressure distillation tower (4) is provided with a pressure distillation tower (5) and a pressure distillation tower (6) in sequence. The lower parts of the pre-distillation tower (1), the negative pressure distillation tower (3), the medium pressure distillation tower (4), the pressure distillation tower (5) and the pressure distillation tower (6) are provided with a pre-tower reboiler (28), a negative pressure tower reboiler (29), a medium pressure tower reboiler (30), a pressure tower (1) reboiler (31) and a pressure tower (2) reboiler (32), respectively. The lower part of the atmospheric distillation tower (2) is provided with an atmospheric pressure tower reboiler (33), an atmospheric pressure tower reboiler (34), and a pressure tower (35). The top of the pre-distillation tower (1) is connected to the atmospheric pressure tower reboiler 1 (33) through the pre-distillation tower top extraction pipeline (35), the top of the atmospheric pressure distillation tower (2) is connected to the negative pressure tower reboiler (29) through the atmospheric pressure tower top extraction pipeline (36), the top of the medium pressure distillation tower (4) is connected to the pre-distillation tower reboiler (28) through the medium pressure tower top extraction pipeline (37), the top of the pressurized distillation tower 1 (5) is connected to the medium pressure tower reboiler (30) and the pressurized tower 2 reboiler (32) through the pressurized tower 1 top extraction pipeline 1 (38) and the pressurized tower 1 top extraction pipeline 2 (39) respectively, and the top of the pressurized distillation tower 2 (6) is connected to the atmospheric pressure tower reboiler 2 (34) through the pressurized tower 2 top extraction pipeline (40).

2. A six-tower thermally coupled refining device for crude methanol according to claim 1, characterized in that: A pre-tower reboiler (43) is provided at the lower part of the pre-distillation tower (1), the input end of the pre-tower reboiler (43) is connected to the steam pipeline (41), and the output end of the pre-tower reboiler (43) is connected to the steam condensate extraction pipeline (42).

3. A six-tower thermally coupled refining device for crude methanol according to claim 1, characterized in that: The atmospheric tower reboiler 1 (33) is connected to the pre-tower reflux device; the pre-tower reflux device comprises a pre-tower top reflux tank (44); the bottom of the pre-tower top reflux tank (44) is connected to the upper part of the pre-distillation tower (1) through a pre-tower reflux pipeline (46); the pre-tower top reflux tank (44) is connected to the bottom of an extraction tank (49) through a pipeline 1 (48); an extraction water pipeline (50) is provided on one side of the extraction tank (49); and a purge gas pipeline (51) is provided on the top of the extraction tank (49); the pre-tower top reflux tank (44) is also connected to the upper part of the extraction tank (49) through a pipeline 2 (52); a pre-tower top reflux tank condenser (53) is provided on the pipeline 2 (52).

4. A six-tower thermally coupled refining device for crude methanol according to claim 1, characterized in that: The negative pressure tower reboiler (29) is connected to the atmospheric pressure tower reflux device; the atmospheric pressure tower reflux device comprises an atmospheric pressure tower reflux tank (62), the bottom of the atmospheric pressure tower reflux tank (62) is connected to the upper part of the atmospheric pressure distillation tower (2) through an atmospheric pressure tower reflux pipeline (64), and the atmospheric pressure tower reflux pipeline (64) is connected to an atmospheric pressure tower refined methanol extraction pipeline (66).

5. The six-tower thermally coupled refining device for crude methanol according to claim 1, characterized in that: The pre-tower reboiler (28) is connected to the medium-pressure tower reflux device; the medium-pressure tower reflux device comprises a medium-pressure tower reflux tank (54), the bottom of the medium-pressure tower reflux tank (54) is connected to the upper part of the medium-pressure distillation tower (4) through a medium-pressure tower reflux pipeline (56), and the medium-pressure tower reflux pipeline (56) is connected to a medium-pressure tower refined methanol extraction pipeline (58).

6. A six-tower thermally coupled refining device for crude methanol according to claim 1, characterized in that: The medium-pressure tower reboiler (30) and the pressure tower second reboiler (32) are respectively connected to the pressure tower first reflux device.

7. A six-tower thermally coupled refining device for crude methanol according to claim 6, characterized in that: The pressurized tower-reflux device comprises a pressurized tower-reflux tank (69), the bottom of which is connected to the upper part of the pressurized distillation tower-1 (5) via a pressurized tower-reflux pipeline (72), and the pressurized tower-refined methanol extraction pipeline (74) is connected to the pressurized tower-reflux pipeline (72).

8. The six-tower thermally coupled refining device for crude methanol according to claim 1, characterized in that: The atmospheric tower reboiler 2 (34) is connected to the pressure tower 2 reflux device; the pressure tower 2 reflux device comprises a pressure tower 2 reflux tank (77), the bottom of the pressure tower 2 reflux tank (77) is connected to the upper part of the pressure distillation tower 2 (6) through a pressure tower 2 reflux pipeline (79), and the pressure tower 2 reflux pipeline (79) is connected to a pressure tower 2 refined methanol extraction pipeline (81).

9. The six-tower thermally coupled refining device for crude methanol according to claim 1, characterized in that: A negative pressure tower reflux device is provided at the top of the negative pressure distillation tower (3), and the negative pressure tower reflux device comprises a negative pressure tower reflux tank (84). The top of the negative pressure distillation tower (3) is connected to the negative pressure tower reflux tank (84) via a negative pressure tower top extraction pipeline (85), and a negative pressure tower top condenser (86) is provided on the negative pressure tower top extraction pipeline (85). The bottom of the negative pressure distillation tower (3) is connected to the negative pressure distillation tower (3) via a negative pressure tower reflux pipeline (87), and the negative pressure tower reflux pipeline (87) is connected to a negative pressure tower refined methanol extraction pipeline (89).

10. A six-tower thermally coupled refining device for crude methanol according to claim 9, characterized in that: The top of the negative pressure tower reflux tank (84) is connected to the absorption tower (92) via an absorption tower connecting pipeline (91); the top of the absorption tower (92) is provided with an absorption tower top extraction pipeline (93); and the absorption tower top extraction pipeline (93) is provided with a vacuum pump (94); the bottom of the absorption tower (92) is connected to the negative pressure distillation tower (3) via an absorption tower reflux pipeline (95).

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