Five-tower five-effect crude methanol rectification equipment

Abstract

The utility model provides five-tower five-effect crude methanol rectification equipment which comprises a pre-rectification tower, a negative pressure rectification tower I, a medium pressure rectification tower, a pressurization rectification tower and a negative pressure rectification tower II, the pre-rectifying tower, the negative pressure rectifying tower I, the medium-pressure rectifying tower, the pressurized rectifying tower and the negative pressure rectifying tower II are respectively provided with a pre-tower reboiler, a negative tower I reboiler, a medium-pressure tower reboiler, a pressurized tower reboiler and a negative tower II reboiler, and tower top steam of the pre-rectifying tower provides heat for the negative tower I reboiler; steam at the top of the medium-pressure rectifying tower provides heat for a pre-tower reboiler and a second negative-tower reboiler, steam at the top of the pressurized rectifying tower provides heat for a medium-pressure tower reboiler, and heat is supplied to the pressurized tower reboiler through steam; the purposes of saving energy and reducing consumption are achieved in a multi-effect thermal coupling mode, only the pressurizing tower reboiler adopts steam heating, other reboilers supply heat through heat of all tower tops, efficient utilization of heat is achieved, then the purposes of saving energy and reducing consumption are achieved, and energy saving is greatly achieved.

Description

Technical Field

[0001] The present application relates to the field of chemical technology, and in particular to a five-tower five-effect crude methanol distillation equipment. Background Art

[0002] Methanol is a widely used basic chemical raw material, which is applied to many fields such as fine chemicals, polymers, pesticides, medicines and energy, and 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 quality requirements. The energy consumption in the methanol distillation process accounts for about 20-30% of the total production energy consumption, which has a great impact on the production cost of the product. The traditional methanol refining process in the chemical industry has the technical characteristics of high output and high energy consumption, and its process flow and heat exchange network have a large room for further improvement. The existing traditional process does not fully utilize the heat of the reboiler and the top condenser of the tower equipment, and basically cools down by direct cooling with circulating water, and the heat is directly lost and exchanged to the atmosphere. The traditional methanol distillation process adopts single-tower distillation or double-tower distillation. Although the equipment investment is relatively low, it has the disadvantages of poor product quality, low methanol recovery rate and huge energy consumption.

[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 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 five-tower five-effect crude methanol distillation equipment, including a pre-distillation tower, which is connected to a negative pressure distillation tower one, a medium-pressure distillation tower, a pressurized distillation tower, and a negative pressure distillation tower two in sequence, and the pre-distillation tower, the negative pressure distillation tower one, the medium-pressure distillation tower, the pressurized distillation tower, and the negative pressure distillation tower two are respectively provided with a pre-tower reboiler, a negative pressure tower one reboiler, a medium-pressure tower reboiler, a pressurized tower reboiler, and a negative pressure tower two reboiler, wherein the top of the pre-distillation tower is connected to the negative pressure tower one reboiler through a pre-tower top extraction pipeline, and the negative pressure tower one reboiler output pipeline is connected to the upper part of the pre-distillation tower through a pre-tower reflux pipeline The top of the medium-pressure distillation tower is connected to the pre-tower reboiler and the negative tower second reboiler respectively through the medium-pressure tower top production pipeline, the pre-tower reboiler output pipeline and the negative tower second reboiler output pipeline are connected to the upper part of the medium-pressure distillation tower through the medium-pressure tower reflux pipeline, and the medium-pressure tower reflux pipeline is connected to the medium-pressure tower refined methanol production pipeline; the top of the pressurized distillation tower is connected to the medium-pressure tower reboiler through the pressurized tower top production pipeline, the medium-pressure tower reboiler output pipeline is connected to the upper part of the pressurized distillation tower through the pressurized tower reflux pipeline, and the pressurized tower reflux pipeline is connected to the pressurized tower refined methanol production pipeline; the pressurized tower reboiler is heated by steam.

[0007] As a preferred solution, a pre-tower reflux device is provided at the top of the pre-distillation tower.

[0008] As a preferred embodiment, the pre-tower reflux device includes a pre-tower reflux tank, the upper part of which is connected to the negative tower-reboiler output pipeline, the lower part of which is connected to the pre-tower reflux tank, and the pre-tower reflux pipeline is connected to the upper part of the pre-distillation tower.

[0009] As a preferred solution, the upper portion of the pre-tower reflux tank is connected to the non-condensable gas treatment device via a pre-tower reflux tank gas phase extraction pipeline.

[0010] As a preferred scheme, the non-condensable gas treatment device includes a gas-liquid separation tank, a pre-tower reflux tank gas phase extraction pipeline is connected to the gas-liquid separation tank, a pre-tower secondary tail gas condenser is arranged on the pre-tower reflux tank gas phase extraction pipeline, a water replenishment port is arranged on one side of the gas-liquid separation tank, a gas phase extraction pipeline is arranged on the top of the gas-liquid separation tank, and the bottom of the gas-liquid separation tank is connected to the pre-tower reflux tank through a liquid phase extraction pipeline.

[0011] As a preferred solution, a negative pressure tower reflux device is provided on the top of the negative pressure distillation tower 1.

[0012] As a preferred embodiment, the negative pressure tower reflux device includes a negative pressure tower reflux tank, the upper part of the negative pressure tower reflux tank is connected to the top of the negative pressure distillation tower 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 tower reflux tank is connected to a negative pressure tower reflux pipeline, the negative pressure tower reflux pipeline is connected to the upper part of the negative pressure distillation tower, and the negative pressure tower reflux pipeline is connected to the refined methanol extraction pipeline.

[0013] As a preferred solution, a negative pressure distillation tower-reflux pump is provided on the negative pressure tower-reflux pipeline.

[0014] As a preferred solution, the refined methanol production pipeline is connected to the refined methanol storage tank.

[0015] As a preferred solution, the upper part of the negative pressure tower-reflux tank is also connected to a negative pressure tower-vacuum buffer tank, and the upper part of the negative pressure tower-vacuum buffer tank is connected to the non-condensable gas treatment device through the vacuum buffer tank extraction pipeline.

[0016] As a preferred scheme, the pre-tower reboiler output pipeline and the negative tower second reboiler output pipeline are respectively connected to the reflux tank of the medium-pressure distillation tower, the bottom of the reflux tank of the medium-pressure distillation tower is connected to the medium-pressure tower reflux pipeline, the medium-pressure tower reflux pipeline is connected to the upper part of the medium-pressure distillation tower, and the medium-pressure tower reflux pipeline is connected to the medium-pressure tower refined methanol production pipeline.

[0017] As a preferred solution, a medium-pressure distillation tower reflux pump is provided on the medium-pressure tower reflux pipeline.

[0018] As a preferred solution, the refined methanol production pipeline of the medium-pressure tower is connected to the refined methanol production pipeline.

[0019] As a preferred solution, the medium-pressure tower reboiler output pipeline is connected to the pressurized distillation tower reflux tank, the bottom of the pressurized distillation tower reflux tank is connected to the pressurized tower reflux pipeline, the pressurized tower reflux pipeline is connected to the upper part of the pressurized distillation tower, and the pressurized tower reflux pipeline is connected to the pressurized tower refined methanol production pipeline.

[0020] As a preferred solution, a pressurized distillation tower reflux pump is provided on the pressurized tower reflux pipeline. As a preferred solution, the pressurized tower refined methanol production pipeline is connected to the refined methanol production pipeline.

[0021] As a preferred solution, the top of the second negative pressure distillation tower is connected with a second negative pressure tower reflux device.

[0022] As a preferred scheme, the negative pressure tower two reflux device includes a negative pressure tower two reflux tank, which is connected to the top of the negative pressure distillation tower two through a negative pressure tower two top production pipeline, and a negative pressure tower two top condenser is arranged on the negative pressure tower two top production pipeline, and the bottom of the negative pressure distillation tower two reflux tank is connected to the upper part of the negative pressure distillation tower two through the negative pressure tower two reflux pipeline, and the negative pressure tower two reflux pipeline is connected to the negative pressure tower two refined methanol production pipeline.

[0023] As a preferred solution, a second reflux pump of the negative pressure distillation tower is provided on the second reflux pipeline of the negative pressure tower.

[0024] As a preferred solution, the negative pressure tower di-refined methanol production pipeline is connected to the refined methanol production pipeline.

[0025] As a preferred solution, the upper part of the negative pressure tower second reflux tank is also connected to the negative pressure tower second vacuum buffer tank, and the upper part of the negative pressure tower second vacuum buffer tank is connected to the non-condensable gas treatment device through the vacuum buffer tank extraction pipeline 2.

[0026] As a preferred scheme, the non-condensable gas treatment device includes a gas-liquid separation tank, which is connected to a gas-liquid feed pipeline, on which a pre-tower secondary tail gas condenser is arranged, the vacuum buffer tank production pipeline and the vacuum buffer tank production pipeline 2 are respectively connected to the gas-liquid feed pipeline, a water replenishment port is arranged on one side of the gas-liquid separation tank, a gas phase production pipeline is arranged on the top of the gas-liquid separation tank, and the bottom of the gas-liquid separation tank is connected to the pre-tower reflux tank through a liquid phase production pipeline.

[0027] As a preferred scheme, the non-condensable gas treatment device includes a gas-liquid separation tank, which is connected to the vacuum buffer tank production pipeline and the vacuum buffer tank production pipeline 2 respectively. The vacuum buffer tank production pipeline and the vacuum buffer tank production pipeline 2 are both provided with a pre-tower secondary tail gas condenser, a water replenishment port is provided on one side of the gas-liquid separation tank, a gas phase production pipeline is provided on the top of the gas-liquid separation tank, and the bottom of the gas-liquid separation tank is connected to the pre-tower reflux tank through a liquid phase production pipeline.

[0028] As a preferred solution, a negative pressure tower-vacuum pump is provided on the production pipeline of the vacuum buffer tank.

[0029] As a preferred solution, a second vacuum pump of a negative pressure tower is provided on the second production pipeline of the vacuum buffer tank.

[0030] As a preferred solution, a pre-tower reboiler 1 is further provided at the lower portion of the pre-distillation tower, and the pre-tower reboiler 1 is heated by steam to provide the heat required for start-up.

[0031] The present application adopts a five-tower process of a pre-distillation tower, a negative pressure distillation tower one, a medium-pressure distillation tower, a pressurized distillation tower, and a negative pressure distillation tower two. Compared with the traditional three-tower process, one medium-pressure distillation tower and two negative pressure distillation towers are added, wherein one negative pressure distillation tower replaces the atmospheric pressure distillation tower in the old process flow, thereby dividing the entire distillation process into multiple towers with different energy levels, which is more convenient to achieve multi-effect thermal coupling to achieve the purpose of energy saving and consumption reduction; the present embodiment achieves the purpose of energy saving and consumption reduction through a multi-effect thermal coupling method, that is, after stable start-up, only the reboiler of the pressurized tower is heated by steam, the top steam of the pressurized distillation tower provides heat for the reboiler of the medium-pressure tower, the top steam of the medium-pressure distillation tower provides heat for the pre-tower reboiler and the negative pressure tower two reboiler, and the top steam of the pre-distillation tower provides heat for the negative tower one reboiler, thereby achieving efficient use of heat, thereby achieving the purpose of energy saving and consumption reduction, and greatly achieving energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of this application;

[0033] 1. Pre-distillation tower; 2. Negative pressure distillation tower 1; 3. Medium pressure distillation tower; 4. Pressurized distillation tower; 5. Negative pressure distillation tower 2; 6. Feed pipeline; 7. Crude methanol feed preheater; 8. Pre-tower kettle extraction pipeline; 9. Negative pressure tower 1 kettle extraction pipeline; 10. Negative pressure tower 1 kettle liquid pump; 11. Medium pressure tower kettle extraction pipeline; 12. Medium pressure tower kettle liquid pump; 13. Pressurized tower kettle extraction pipeline; 14. Negative pressure tower 2 side extraction of fusel alcohol tank; 15. Fusel alcohol extraction pipeline 1; 16. Negative pressure tower 2 fusel alcohol side extraction condenser; 17. Fusel alcohol extraction pipeline 2; 18. Fusel alcohol extraction pump; 19. Wastewater extraction pipeline; 20. Negative pressure tower 2 kettle liquid pump; 21. Pre-tower reboiler; 22. Negative tower 1 reboiler; 23. Medium-pressure tower reboiler; 24. Pressure tower reboiler; 25. Negative tower 2 reboiler; 26. Pre-tower reboiler 1; 27. Steam pipeline; 28. Steam condensate extraction pipeline; 29. ​​Pre-tower top extraction pipeline; 30. Negative tower 1 reboiler output pipeline; 31. Pre-tower reflux pipeline; 32. Pre-tower reflux pump; 33. Medium-pressure tower top extraction pipeline; 34. Pre-tower reboiler output pipeline; 35. Medium-pressure tower reflux pipeline; 36. Medium-pressure tower refined methanol extraction pipeline; 37. Negative tower 2 reboiler output pipeline; 38. Pressure tower top extraction pipeline; 39. Medium-pressure tower reboiler Output pipeline; 40, pressure tower reflux pipeline; 41, pressure tower refined methanol extraction pipeline; 42, pre-tower reflux tank; 43, negative pressure tower one reflux tank; 44, negative pressure tower one tower top extraction pipeline; 45, negative pressure tower one tower top condenser; 46, negative pressure tower one reflux pipeline; 47, negative pressure distillation tower one reflux pump; 48, refined methanol extraction pipeline; 49, refined methanol storage tank; 50, medium pressure distillation tower reflux tank; 51, medium pressure distillation tower reflux pump; 52, pressure distillation tower reflux tank; 53, pressure distillation tower reflux pump; 54, negative pressure tower two reflux tank; 55, negative pressure tower two top extraction pipeline; 56, negative pressure tower two tower top condenser; 57, Reflux pipeline of negative pressure tower two; 58, reflux pump of negative pressure distillation tower two; 59, methanol production pipeline of negative pressure tower two; 60, vacuum buffer tank of negative pressure tower one; 61, production pipeline of vacuum buffer tank; 62, gas-liquid separation tank; 63, gas-liquid feed pipeline; 64, water replenishment port; 65, gas phase production pipeline; 66, liquid phase production pipeline; 67, vacuum pump of negative pressure tower one; 68, secondary tail gas condenser of pre-tower; 69, reflux pipeline of buffer tank; 70, vacuum buffer tank of negative pressure tower two; 71, production pipeline of vacuum buffer tank two; 72, reflux pipeline of vacuum buffer tank two; 73, vacuum pump of negative pressure tower two; 74, gas phase production pipeline of pre-tower reflux tank. DETAILED DESCRIPTION

[0034] 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.

[0035] Embodiment 1:

[0036] The present embodiment provides a five-tower five-effect crude methanol distillation equipment, comprising a pre-distillation tower 1, a negative pressure distillation tower 2, a medium pressure distillation tower 3, a pressurized distillation tower 4, and a negative pressure distillation tower 2 5 which are connected in sequence. More specifically, 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 for preheating the material entering the pre-distillation tower 1 to improve the stability of distillation. A pre-tower kettle extraction pipeline 8 at the bottom of the pre-distillation tower 1 is connected to the negative pressure distillation tower 2, a negative tower kettle extraction pipeline 9 of the negative pressure distillation tower 2 is connected to the medium pressure distillation tower 3, a negative tower kettle extraction pipeline 9 is provided with a negative tower kettle liquid pump 10, a medium pressure tower kettle extraction pipeline 11 at the bottom of the medium pressure distillation tower 3 is connected to the pressurized distillation tower 4, and a medium pressure tower kettle extraction pipeline 11 is provided with a medium pressure The tower reactor liquid pump 12, the pressure tower reactor extraction pipeline 13 at the bottom of the pressure distillation tower 4 is connected to the negative pressure distillation tower 2 5, and a fusel alcohol extraction device is arranged on one side of the negative pressure distillation tower 2 5, and the fusel alcohol extraction device includes a fusel alcohol extraction tank 14 on the second side of the negative pressure tower, and the fusel alcohol extraction tank 14 on the second side of the negative pressure tower is connected to one side of the negative pressure distillation tower 2 5 through a fusel alcohol extraction pipeline 15, and a fusel alcohol extraction pipeline 15 is arranged on a negative pressure A condenser 16 is provided on the side of the second fusel alcohol extraction tank 14 of the second negative pressure tower, and a fusel alcohol extraction pipeline 17 is connected to the bottom of the second fusel alcohol extraction tank 14, and a fusel alcohol extraction pump 18 is arranged on the second fusel alcohol extraction pipeline 17; a wastewater extraction pipeline 19 is provided at the bottom of the second negative pressure distillation tower 5, and a second negative pressure tower bottom liquid pump 20 is arranged on the wastewater extraction pipeline 19, and the wastewater extraction pipeline 19 is used to extract the bottom waste water in the second negative pressure distillation tower 5.

[0037] The pre-distillation tower 1, negative pressure distillation tower 2, medium pressure distillation tower 3, pressurized distillation tower 4 and negative pressure distillation tower 2 are respectively provided with a pre-tower reboiler 21, negative pressure tower 1 reboiler 22, medium pressure tower reboiler 23, pressurized tower reboiler 24 and negative pressure tower 2 reboiler 25. In order to provide the heat required for startup, the lower part of the pre-distillation tower 1 is also provided with a pre-tower reboiler 26. The input end of the pre-tower reboiler 26 is connected to the steam pipeline 27, and the output end of the pre-tower reboiler 26 is connected to the steam condensate extraction pipeline 28. The steam is used to provide the pre-distillation tower 1 with the heat required for startup. , after the start-up is stable, turn off the steam heating; wherein, the top of the pre-distillation tower 1 is connected to the negative tower-reboiler 22 through the pre-tower top extraction pipeline 29, and the negative tower-reboiler output pipeline 30 of the negative tower-reboiler 22 is connected to the upper part of the pre-distillation tower 1 through the pre-tower reflux pipeline 31, and the pre-tower reflux pipeline 31 is provided with a pre-tower reflux pump 32, and the material extracted from the top of the pre-distillation tower 1 is heat-exchanged with the negative tower-reboiler 22, 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 negative tower-reboiler 22, thereby improving the utilization rate of heat;

[0038] The top of the medium-pressure distillation tower 3 is connected to the pre-tower reboiler 21 and the negative tower second reboiler 25 respectively through the medium-pressure tower top extraction pipeline 33, the pre-tower reboiler output pipeline 34 of the pre-tower reboiler 21 and the negative tower second reboiler output pipeline 37 of the negative tower second reboiler 25 are connected to the upper part of the medium-pressure distillation tower 3 through the medium-pressure tower reflux pipeline 35, and the medium-pressure tower reflux pipeline 35 is connected to the medium-pressure tower refined methanol extraction pipeline 36; the top of the medium-pressure distillation tower 3 is extracted The material exchanges heat with the pre-tower reboiler 21, and part of the material after heat exchange flows back to the medium-pressure distillation tower 3, and part of it is extracted as refined methanol. The material extracted from the top of the medium-pressure distillation tower 3 exchanges heat with the negative tower second reboiler 25, and part of the material after heat exchange flows back to the medium-pressure distillation tower 3, and part of it is extracted as refined methanol. The heat at the top of the medium-pressure distillation tower 3 is used to heat the pre-tower reboiler 21 and the negative tower second reboiler 25, thereby improving the utilization rate of heat;

[0039] The top of the pressurized distillation tower 4 is connected to the medium-pressure tower reboiler 23 through the pressurized tower top extraction pipeline 38, and the medium-pressure tower reboiler output pipeline 39 of the medium-pressure tower reboiler 23 is connected to the upper part of the pressurized distillation tower 4 through the pressurized tower reflux pipeline 40, and the pressurized tower reflux pipeline 40 is connected to the pressurized tower refined methanol extraction pipeline 41; the material extracted from the top of the pressurized distillation tower 4 is heat-exchanged with the medium-pressure tower reboiler 23, and part of the heat-exchanged material is refluxed to the pressurized distillation tower 4, and part of it is extracted as refined methanol, and the heat from the top of the pressurized distillation tower 4 is used to heat the medium-pressure tower reboiler 23, thereby improving the utilization rate of heat;

[0040] The input end of the pressure tower reboiler 24 is connected to the steam pipeline 27, and the output end of the pressure tower reboiler 24 is connected to the steam condensate extraction pipeline 28. The pressure tower reboiler 24 is heated by external steam to provide the required heat for the pressure tower reboiler 24.

[0041] In the present embodiment, a five-tower process of a pre-distillation tower 1, a negative pressure distillation tower 2, a medium pressure distillation tower 3, a pressurized distillation tower 4, and a negative pressure distillation tower 2 5 is adopted. Compared with the traditional three-tower process, one medium pressure distillation tower and two negative pressure distillation towers are added, wherein one negative pressure distillation tower replaces the atmospheric distillation tower in the old process flow, thereby dividing the entire distillation process into a plurality of towers with different energy levels, making it easier to achieve heat multi-effect coupling to achieve energy saving and consumption reduction; the present embodiment achieves the purpose of energy saving and consumption reduction through a multi-effect heat coupling mode, that is, after stable start-up, only the pressurized tower reboiler 24 is heated by steam, the top steam of the pressurized distillation tower 4 provides heat for the medium pressure tower reboiler 23, the top steam of the medium pressure distillation tower 3 provides heat for the pre-tower reboiler 21 and the negative pressure tower 2 reboiler 25, and the top steam of the pre-distillation tower 1 provides heat for the negative tower 1 reboiler 22, thereby achieving efficient use of heat, thereby achieving the purpose of energy saving and consumption reduction, and greatly achieving energy saving.

[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 1 reflux device at the top of the negative pressure distillation tower 2, the medium pressure tower reflux at the top of the medium pressure distillation tower 3, the pressure tower reflux at the top of the pressure distillation tower 4, and the negative pressure tower 2 reflux device at the top of the negative pressure distillation tower 2 5 are described, specifically:

[0044] The pre-tower reflux device comprises a pre-tower reflux tank 42, the upper part of which is connected to the negative tower-reboiler output pipeline 30, the lower part of which is connected to the pre-tower reflux pipeline 31, and the pre-tower reflux pipeline 31 is connected to the upper part of the pre-distillation tower 1; preferably, the upper part of the pre-tower reflux tank is connected to the non-condensable gas treatment device through the pre-tower reflux tank gas phase extraction pipeline 74; the non-condensable gas treatment device comprises a gas-liquid separation tank 62, the pre-tower reflux tank gas phase extraction pipeline 74 is connected to the gas-liquid separation tank 62, a pre-tower secondary tail gas condenser 68 is arranged on the pre-tower reflux tank gas phase extraction pipeline 74, and a water supply is arranged on one side of the gas-liquid separation tank 62. Port 64, a gas phase extraction pipeline 65 is arranged on the top of the gas-liquid separation tank 62, and the bottom of the gas-liquid separation tank 62 is connected to the pre-tower reflux tank 42 through a liquid phase extraction pipeline 66; the material extracted from the top of the pre-distillation tower 1 is heat-exchanged with the negative tower-reboiler 22 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 reflux tank 42, and the non-condensable gas phase in the pre-tower reflux tank 42 is extracted through the pre-tower reflux tank gas phase extraction pipeline 74, and enters the gas-liquid separation tank 62 after being cooled by the pre-tower secondary tail gas condenser 68, and the liquid phase in the gas-liquid separation tank 62 flows into the pre-tower reflux tank 42, and the non-condensable gas is extracted through the gas phase extraction pipeline 65.

[0045] A negative pressure tower-reflux device is arranged at the top of the negative pressure distillation tower-2, and the negative pressure tower-reflux device comprises a negative pressure tower-reflux tank 43, the upper part of the negative pressure tower-reflux tank 43 is connected to the top of the negative pressure distillation tower-2 through a negative pressure tower-top extraction pipeline 44, a negative pressure tower-top condenser 45 is arranged on the negative pressure tower-top extraction pipeline 44, a negative pressure tower-reflux tank 43 is connected to the bottom of the negative pressure tower-reflux tank 43, a negative pressure tower-reflux pipeline 46 is arranged on the negative pressure tower-reflux pipeline 46, a negative pressure distillation tower-reflux pump 47 is arranged on the negative pressure tower-reflux pipeline 46, and a negative pressure tower-reflux pipeline 46 is connected to the negative pressure tower-reflux pipeline 46. It is connected to the refined methanol extraction pipeline 48. Preferably, the refined methanol extraction pipeline 48 is connected to the refined methanol storage tank 49, which is used to store the refined methanol extracted from the top of the negative pressure distillation tower-2; the material extracted from the top of the negative pressure distillation tower-2 is condensed by the negative pressure tower-top condenser 45 and then enters the negative pressure tower-reflux tank 43, the gas phase in the negative pressure tower-reflux tank 43 is extracted, a part of the liquid phase in the negative pressure tower-reflux tank 43 flows back to the negative pressure distillation tower-2, and a part is extracted as refined methanol through the refined methanol extraction pipeline 48, preferably, directly extracted into the refined methanol storage tank 49 for storage.

[0046] The pre-tower reboiler output pipeline 34 and the negative tower second reboiler output pipeline 37 are respectively connected to the medium-pressure distillation tower reflux tank 50, and the bottom of the medium-pressure distillation tower reflux tank 50 is connected to the medium-pressure tower reflux pipeline 35, and the medium-pressure tower reflux pipeline 35 is connected to the upper part of the medium-pressure distillation tower 3; the medium-pressure tower reflux pump 51 is arranged on the medium-pressure distillation tower reflux pipeline 35, and the medium-pressure tower reflux pipeline 35 is connected to the medium-pressure tower refined methanol extraction pipeline 36, preferably, the medium-pressure tower refined methanol extraction pipeline 36 is connected to the refined methanol extraction pipeline 48; the medium-pressure distillation tower The material taken out from the top of the medium-pressure distillation tower 3 is heat-exchanged with the pre-tower reboiler 21 and the second negative tower reboiler 25, so as to make full use of the heat at the top of the medium-pressure distillation tower 3. The materials after heat exchange in the two reboilers all enter the reflux tank 50 of the medium-pressure distillation tower. A part of the liquid phase in the reflux tank 50 of the medium-pressure distillation tower is refluxed to the medium-pressure distillation tower 3, and a part of the liquid phase is taken out as refined methanol through the refined methanol extraction pipeline 36 of the medium-pressure tower. The refined methanol can be mixed with the refined methanol in the refined methanol extraction pipeline 48 and then extracted, or it can be extracted separately. The technicians can make a choice according to the specific situation, and there is no specific limitation.

[0047] The medium-pressure tower reboiler output pipeline 39 is connected to the pressurized distillation tower reflux tank 52, the bottom of the pressurized distillation tower reflux tank 52 is connected to the pressurized tower reflux pipeline 40, the pressurized tower reflux pipeline 40 is connected to the upper part of the pressurized distillation tower 4, and the pressurized tower reflux pump 53 is arranged on the pressurized tower reflux pipeline 40; the pressurized tower reflux pipeline 40 is connected to the pressurized tower refined methanol extraction pipeline 41; preferably, the pressurized tower refined methanol extraction pipeline 41 is connected to the refined methanol extraction pipeline 48; the pressurized distillation tower 4 The material taken out from the top of the tower is heat exchanged with the reboiler 23 of the medium-pressure tower to make full use of the heat at the top of the pressurized distillation tower 4. The material after heat exchange enters the reflux tank 52 of the pressurized distillation tower. Part of the liquid phase in the reflux tank 52 of the pressurized distillation tower is refluxed to the pressurized distillation tower 4, and part of it is taken out as refined methanol through the refined methanol production pipeline 41 of the pressurized tower; the refined methanol can be mixed with the refined methanol in the refined methanol production pipeline 48 and then taken out, or it can be taken out separately. The technicians can make a choice according to the specific situation, and there is no specific limitation.

[0048] The top of the negative pressure distillation tower 2 5 is connected with a negative pressure tower 2 reflux device, and the negative pressure tower 2 reflux device includes a negative pressure tower 2 reflux tank 54, and the negative pressure tower 2 reflux tank 54 is connected to the top of the negative pressure distillation tower 2 5 through a negative pressure tower 2 top extraction pipeline 55, and a negative pressure tower 2 top condenser 56 is arranged on the negative pressure tower 2 top extraction pipeline 55, and the bottom of the negative pressure tower 2 reflux tank 54 is connected to the upper part of the negative pressure distillation tower 2 5 through a negative pressure tower 2 reflux pipeline 57, and a negative pressure tower 2 reflux pump 58 is arranged on the negative pressure tower 2 reflux pipeline 57, and the negative pressure tower 2 reflux pump 58 is connected to the negative pressure tower 2 methanol extraction pipeline 57. Pipeline 59; preferably, the negative pressure tower two refined methanol extraction pipeline 59 is connected to the refined methanol extraction pipeline 48; the material extracted from the top of the negative pressure distillation tower two 5 is condensed by the negative pressure tower two top condenser 56 and then enters the negative pressure tower two reflux tank 54, the gas phase in the negative pressure tower two reflux tank 54 is extracted, a part of the liquid phase in the negative pressure tower two reflux tank 54 is refluxed to the negative pressure distillation tower two 5, and a part of it is extracted as refined methanol through the negative pressure tower two refined methanol extraction pipeline 59. The refined methanol can be mixed with the refined methanol in the refined methanol extraction pipeline 48 and then extracted, or it can be extracted separately. The technicians can make a choice according to the specific situation, and there is no specific limitation.

[0049] Embodiment three:

[0050] In this embodiment, the gas phase extracted from the negative pressure tower 1 reflux tank 43 and the negative pressure tower 2 reflux tank 54 is further processed to recover methanol in the tail gas, specifically:

[0051] The upper part of the negative pressure tower-reflow tank 43 is also connected to a negative pressure tower-vacuum buffer tank 60, and the upper part of the negative pressure tower-vacuum buffer tank 60 is connected to the non-condensable gas treatment device through a vacuum buffer tank extraction pipeline 61. The non-condensable gas treatment device includes a gas-liquid separation tank 62, and the vacuum buffer tank extraction pipeline 61 is connected to the gas-liquid separation tank 62. A water replenishment port 64 is provided on one side of the gas-liquid separation tank 62, and a gas phase extraction pipeline 65 is provided on the top of the gas-liquid separation tank 62. The bottom of the gas-liquid separation tank 62 is connected to the pre-tower reflux tank 42 through a liquid phase extraction pipeline 66. Then, the vacuum buffer tank production pipeline 61 is sequentially provided with a negative pressure tower vacuum pump 67 and a pre-tower secondary tail gas condenser 68; the gas phase in the negative pressure tower reflux tank 43 enters the negative pressure tower vacuum buffer tank 60 for buffering, and the liquid phase flows back to the negative pressure tower reflux tank 43 through the vacuum buffer tank reflux pipeline 69, and a part of the gas-liquid mixed phase is condensed through the pre-tower secondary tail gas condenser 68 on the gas-liquid feed pipeline 63 and then enters the gas-liquid separation tank 62; the liquid phase in the gas-liquid separation tank 62 flows into the pre-tower reflux tank 42, and the gas phase is produced through the gas phase production pipeline 65.

[0052] Similarly, the upper part of the negative pressure tower second reflux tank 54 is also connected to the negative pressure tower second vacuum buffer tank 70, and the upper part of the negative pressure tower second vacuum buffer tank 70 is connected to the non-condensable gas treatment device through the vacuum buffer tank extraction pipeline 2 71. The non-condensable gas treatment device is the same as above and will not be described in detail here. Specifically, the vacuum buffer tank extraction pipeline 2 71 is connected to the gas-liquid separation tank 62; the vacuum buffer tank extraction pipeline 2 71 is sequentially provided with a negative pressure tower second vacuum pump 73 and a pre-tower secondary tail gas condenser 68; the gas phase in the negative pressure tower second reflux tank 54 enters the negative pressure tower second vacuum buffer tank 70 for buffering, and the liquid phase flows back to the negative pressure tower second reflux tank 54 through the vacuum buffer tank second reflux pipeline 72, and the gas-liquid mixed phase enters the gas-liquid separation tank 62 after being condensed by the pre-tower secondary tail gas condenser 68; the liquid phase in the gas-liquid separation tank 62 flows into the pre-tower reflux tank 43, and the gas phase is extracted through the gas phase extraction pipeline 65.

[0053] In addition, in the present embodiment, the gas-liquid separation tank 62 can also be connected to the gas-liquid feed pipeline 63, and a pre-tower secondary tail gas condenser 68 is arranged on the gas-liquid feed pipeline 63. The vacuum buffer tank production pipeline 61, the vacuum buffer tank production pipeline 2 71, and the pre-tower reflux tank gas phase production pipeline 74 are respectively connected to the gas-liquid feed pipeline 63, and a water replenishment port 64 is arranged on one side of the gas-liquid separation tank 62. A gas phase production pipeline 65 is arranged on the top of the gas-liquid separation tank 62, and the bottom of the gas-liquid separation tank 62 is connected to the pre-tower reflux tank 42 through a liquid phase production pipeline 66. A negative pressure tower one vacuum pump 67 is arranged on the vacuum buffer tank production pipeline 61, and a negative pressure tower two vacuum pump 73 is arranged on the vacuum buffer tank production pipeline 2 71.

[0054] That is, in this embodiment, the non-condensable gas phase of the vacuum buffer tank production pipeline 61, the vacuum buffer tank production pipeline 2 71, and the pre-tower reflux tank gas phase production pipeline 74 can be condensed through the pre-tower secondary tail gas condenser 68 and then enter the gas-liquid separation tank 62, or the non-condensable gas phase of the vacuum buffer tank production pipeline 61, the vacuum buffer tank production pipeline 2 71, and the pre-tower reflux tank gas phase production pipeline 74 can first be mixed through the gas-liquid feed pipeline 63, and then condensed through the pre-tower secondary tail gas condenser 68 and enter the gas-liquid separation tank 62 together. The technicians can make corresponding choices according to the specific situation, and this embodiment does not make any specific limitations.

[0055] After experiments, it was found that when the device of the present application is used in a process with an annual output of 300,000 tons of refined methanol, when the ethanol content of the refined methanol product is ≤10ppm, considering energy saving and consumption reduction, the steam unit consumption can reach 0.53t / t of refined methanol; when the ethanol content of the refined methanol product is ≤50ppm, considering energy saving and consumption reduction, the steam unit consumption can reach 0.49t / t of refined methanol. The steam unit consumption of this process is approximately 0.49-0.53t / t of refined methanol, which has lower steam unit consumption than a five-tower four-effect crude methanol refining device in the prior art.

[0056] The working principle of the present application is as follows: the raw material crude methanol is preheated and enters the pre-distillation tower 1, after the light components are removed by the pre-distillation tower 1, it enters the negative pressure distillation tower 2, part of the refined methanol product is extracted from the top of the negative pressure distillation tower 2, the bottom liquid is sent to the medium pressure distillation tower 3 for further distillation, part of the refined methanol product is extracted from the top of the medium pressure distillation tower 3, the bottom liquid is sent to the pressure distillation tower 4 for further distillation, part of the refined methanol product is extracted from the top of the pressure distillation tower 4, the bottom liquid is sent to the negative pressure distillation tower 2 5 for further distillation, refined methanol is extracted from the top of the negative pressure distillation tower 2 5, higher carbon fusel alcohols with higher boiling points are extracted through side extraction, and the bottom waste water is sent to wastewater treatment.

[0057] In summary, due to the adoption of the above technical scheme, compared with the traditional three-tower two-effect process, the present application cancels the atmospheric distillation tower, adds two negative pressure distillation towers and one medium-pressure distillation tower, and has a more significant energy-saving effect. The traditional three-tower two-effect process has a steam unit consumption of about 1.2t / t of refined methanol, and the steam unit consumption of this process is about 0.49-0.53t / t of refined methanol; the present application adopts a multi-effect thermal coupling method to achieve the purpose of energy saving and consumption reduction. Compared with a five-tower four-effect crude methanol refining device in the prior art, it only needs to heat the pressure tower reboiler with steam, and the top steam of the pressure distillation tower provides heat for the medium-pressure tower reboiler, the top steam of the medium-pressure distillation tower provides heat for the pre-tower reboiler and the negative tower two reboiler, and the top steam of the pre-distillation tower provides heat for the negative tower one reboiler, thereby achieving the purpose of energy saving and consumption reduction, and reducing the steam unit consumption from 0.62t / t of refined methanol to 0.49-0.53t / t of refined methanol, with better energy-saving effect.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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 five-effect crude methanol distillation device, comprising a pre-distillation tower (1), characterized in that: The pre-distillation tower (1) is connected to the negative pressure distillation tower (2), the medium pressure distillation tower (3), the pressure distillation tower (4), and the negative pressure distillation tower (5) in sequence. The pre-distillation tower (1), the negative pressure distillation tower (2), the medium pressure distillation tower (3), the pressure distillation tower (4), and the negative pressure distillation tower (5) are respectively provided with a pre-tower reboiler (21), a negative pressure tower reboiler (22), a medium pressure tower reboiler (23), a pressure tower reboiler (24), and a negative pressure tower reboiler (25). The top of the pre-distillation tower (1) is connected to the negative pressure tower reboiler (22) via a pre-tower top extraction pipeline (29), and the negative pressure tower reboiler output pipeline (30) is connected to the upper part of the pre-distillation tower (1) via a pre-tower reflux pipeline (31); the top of the medium pressure distillation tower (3 ... The top extraction pipeline (33) of the medium-pressure tower is connected to the pre-tower reboiler (21) and the negative tower second reboiler (25) respectively; the pre-tower reboiler output pipeline (34) and the negative tower second reboiler output pipeline (37) are connected to the upper part of the medium-pressure distillation tower (3) through the medium-pressure tower reflux pipeline (35); the medium-pressure tower reflux pipeline (35) is connected to the medium-pressure tower refined methanol extraction pipeline (36); the top of the pressurized distillation tower (4) is connected to the medium-pressure tower reboiler (23) through the pressurized tower top extraction pipeline (38); the medium-pressure tower reboiler output pipeline (39) is connected to the upper part of the pressurized distillation tower (4) through the pressurized tower reflux pipeline (40); the pressurized tower reflux pipeline (40) is connected to the pressurized tower refined methanol extraction pipeline (41); the pressurized tower reboiler (24) is heated by steam.

2. A five-tower five-effect crude methanol distillation equipment according to claim 1, characterized in that: A pre-tower reflux device is provided at the top of the pre-distillation tower (1).

3. A five-tower five-effect crude methanol distillation equipment according to claim 1, characterized in that: The top of the negative pressure distillation tower 1 (2) is provided with a negative pressure tower 1 reflux device, and the top of the negative pressure distillation tower 2 (5) is connected with a negative pressure tower 2 reflux device.

4. A five-tower five-effect crude methanol distillation equipment according to claim 3, characterized in that: The negative pressure tower reflux device comprises a negative pressure tower reflux tank (43), the upper part of the negative pressure tower reflux tank (43) is connected to the top of the negative pressure distillation tower (2) through a negative pressure tower top extraction pipeline (44), a negative pressure tower top condenser (45) is arranged on the negative pressure tower top extraction pipeline (44), the bottom of the negative pressure tower reflux tank (43) is connected to a negative pressure tower reflux pipeline (46), the negative pressure tower reflux pipeline (46) is connected to the upper part of the negative pressure distillation tower (2), and the negative pressure tower reflux pipeline (46) is connected to a refined methanol extraction pipeline (48).

5. A five-tower five-effect crude methanol distillation equipment according to claim 4, characterized in that: The upper part of the negative pressure tower-reflow trough (43) is also connected to a negative pressure tower-vacuum buffer tank (60), and the upper part of the negative pressure tower-vacuum buffer tank (60) is connected to the pre-tower reflux trough (42) through a vacuum buffer tank extraction pipeline (61), and the vacuum buffer tank extraction pipeline (61) is also connected to a non-condensable gas treatment device.

6. A five-tower five-effect crude methanol distillation equipment according to claim 3, characterized in that: The negative pressure tower 2 reflux device comprises a negative pressure tower 2 reflux tank (54), the negative pressure tower 2 reflux tank (54) is connected to the top of the negative pressure distillation tower 2 (5) through a negative pressure tower 2 top extraction pipeline (55), a negative pressure tower 2 top condenser (56) is arranged on the negative pressure tower 2 top extraction pipeline (55), and the bottom of the negative pressure distillation tower 2 reflux tank (54) is connected to the upper part of the negative pressure distillation tower 2 (5) through a negative pressure tower 2 reflux pipeline (57).

7. A five-tower five-effect crude methanol distillation equipment according to claim 6, characterized in that: The upper part of the negative pressure tower second reflux tank (54) is also connected to the negative pressure tower second vacuum buffer tank (70), and the upper part of the negative pressure tower second vacuum buffer tank (70) is connected to the non-condensable gas treatment device through the vacuum buffer tank extraction pipeline (71).

8. A five-tower five-effect crude methanol distillation equipment according to claim 5 or 7, characterized in that: The non-condensable gas treatment device comprises a gas-liquid separation tank (62), the gas-liquid separation tank (62) is connected to a gas-liquid feed pipeline (63), a pre-tower secondary tail gas condenser (68) is arranged on the gas-liquid feed pipeline (63), the vacuum buffer tank production pipeline (61) and the vacuum buffer tank production pipeline 2 (71) are respectively connected to the gas-liquid feed pipeline (63), a water replenishment port (64) is arranged on one side of the gas-liquid separation tank (62), a gas phase production pipeline (65) is arranged on the top of the gas-liquid separation tank (62), and the bottom of the gas-liquid separation tank (62) is connected to the pre-tower reflux tank (42) through a liquid phase production pipeline (66).

9. A five-tower five-effect crude methanol distillation equipment according to claim 5 or 7, characterized in that: The non-condensable gas treatment device comprises a gas-liquid separation tank (62), the gas-liquid separation tank (62) is connected to a vacuum buffer tank production pipeline (61) and a vacuum buffer tank production pipeline 2 (71) respectively, the vacuum buffer tank production pipeline (61) and the vacuum buffer tank production pipeline 2 (71) are both provided with a pre-tower secondary tail gas condenser (68), a water replenishment port (64) is provided on one side of the gas-liquid separation tank, a gas phase production pipeline (65) is provided on the top of the gas-liquid separation tank (62), and the bottom of the gas-liquid separation tank (62) is connected to the pre-tower reflux tank (42) via a liquid phase production pipeline (66).

10. The five-tower five-effect crude methanol distillation equipment according to claim 1, characterized in that: The pre-tower reboiler output pipeline (34) and the negative tower second reboiler output pipeline (37) are respectively connected to the medium-pressure distillation tower reflux tank (50), and the bottom of the medium-pressure distillation tower reflux tank (50) is connected to the medium-pressure tower reflux pipeline (35), and the medium-pressure tower reflux pipeline (35) is connected to the upper part of the medium-pressure distillation tower (3).

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