Methanol energy-saving recovery device for sodium methoxide production

Abstract

The utility model provides a methanol energy-saving recovery device for sodium methoxide production, the methanol energy-saving recovery device comprises a reaction tower, a rectifying tower, a negative pressure tower, a secondary pressurizing tower and a pressurizing tower which are connected in sequence, a part of refined methanol gas phase at the top of the rectifying tower provides heat for a tower kettle of the reaction tower after being compressed, and a part of refined methanol gas phase provides heat for a rectifying tower reboiler after being compressed; a refined methanol gas phase at the top of the secondary pressurizing tower provides heat for a reboiler of the negative pressure tower; a refined methanol gas phase at the top of the pressurizing tower provides heat for a secondary pressurizing tower reboiler; an innovative efficient energy-saving technology is adopted, the recovery efficiency of methanol is remarkably improved, energy consumption is reduced, the overall production process is optimized, the mature reaction tower, rectifying tower, negative pressure tower, secondary pressurizing tower and pressurizing tower are adopted as equipment, the structure is simple, and then the installation, debugging and maintenance difficulty of the equipment is low; mature equipment is not prone to faults, and stability and continuity of production are guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of methanol recovery in the synthesis field of sodium methoxide, and specifically relates to an energy-saving methanol recovery device for sodium methoxide production. Background Art

[0002] Sodium methoxide is an important chemical product, mainly used as an intermediate raw material for the synthesis of pharmaceuticals and pesticides, and can also be used as a catalyst for the production of edible oil and biodiesel and an analytical reagent, with good market prospects; at present, the main production methods of sodium methoxide in China are the alkali method and the metallic sodium method, both of which have achieved large-scale industrialization.

[0003] The metallic sodium method refers to the direct reaction of metallic sodium with alcohol to produce sodium alkoxide and hydrogen. This method has a simple process, but the production process is extremely unsafe, and metallic sodium is expensive; the alkali method uses sodium hydroxide to react with methanol to produce sodium methoxide, and the reaction equation is: CH 3 OH + NaOH → CH 3 ONa + H 2 O; because the metallic sodium method has low safety and high cost, therefore, in large-scale continuous industrial production, the alkali method is mostly used to produce sodium methoxide in a reaction stripping tower, and the cost of the alkali method is relatively low; however, there are some technical and economic challenges in the production of sodium methoxide by the alkali method. For example, the alkalinity of sodium methoxide is stronger than that of sodium hydroxide, and the generated sodium methoxide is extremely easy to regenerate methanol and sodium hydroxide when encountering water. Therefore, for economic factors, resource utilization efficiency, environmental protection requirements, process stability, etc., it is necessary to recover methanol.

[0004] There are mainly the following important reasons for recovering methanol in the synthesis process of sodium methoxide: 1. Economic factors: Methanol is a raw material with a cost. If not recovered, a large amount of new methanol needs to be used each time sodium methoxide is synthesized, which will significantly increase the production cost; by recovering methanol, the cost of purchasing new methanol can be reduced, and the economic benefits of production can be improved; 2. Resource utilization efficiency: Methanol is a limited resource, and recovering methanol helps to improve the resource utilization efficiency, which conforms to the principle of sustainable development; 3. Environmental protection requirements: A large amount of waste methanol discharged into the environment without recovery will cause environmental pollution. Recovering methanol can reduce the environmental pollution pressure and reduce the environmental liability risk of enterprises; in summary, it is very necessary to recover methanol in the synthesis of sodium methoxide, which is of great significance for reducing costs, protecting the environment, improving resource utilization efficiency and ensuring process stability.

[0005] In the solid sodium methoxide production device using a vacuum pump to recover methanol with the application number CN201920407371.X, a technical solution is disclosed, including a sodium methoxide synthesis unit, a rake dryer, and a methanol negative pressure recovery device. In the present utility model, the force exerted by the knocking rod on the second blocking block is perpendicular to the fixing rod, and the rotating shaft connected to the fixing rod is only affected by the torque of the knocking rod, which will not cause the rotating shaft to bend. The knocking rod strikes the second blocking block and then provides vibration to the fixing rod and the rotating shaft, which can remove the material adhesion on the rotating shaft. The diversion sieve plates arranged in a staggered manner from top to bottom in the cooling tower body can effectively utilize the condensed liquid methanol to capture methanol gas, thereby promoting the condensation of methanol gas, effectively recovering the methanol gas volatilized in the rake dryer, and reducing the problem of low methanol recovery rate caused by the external discharge of the methanol gas that is not condensed in time. The multi-stage cooling unit can adjust the number of coolers through which the top steam flows according to different extraction amounts, avoiding insufficient cooling or overcooling of a single cooler; the multi-stage cooling unit provided in this application has three coolers, and the top steam is gradually cooled by one or several of the three coolers and then sent to a temporary storage tank, and then flows back through a pipeline to one or several of the three coolers for circulating cooling, which can ensure the cooling process requirements. Compared with a single cooler, the multi-stage cooling unit can adjust the number of coolers through which the top steam flows according to different extraction amounts, and can also adjust the number of coolers for reflux, avoiding the disadvantages of insufficient cooling or overcooling of a single cooler, ensuring the reasonable consumption of energy, and meeting the requirements for precise control of the operating conditions of the synthesis tower and the rectification tower; however, this application includes multiple components such as a sodium methoxide synthesis unit, a rake dryer, and a methanol negative pressure recovery device, as well as relatively complex structures such as a knocking rod, a blocking block, a rotating shaft, a diversion sieve plate, and a multi-stage cooling unit, which may lead to an increase in the difficulty of equipment installation, debugging, and maintenance; the complex equipment structure may also be more prone to failures, affecting the stability and continuity of production, and although the device mentions that the multi-stage cooling unit can be adjusted according to different extraction amounts to avoid insufficient or excessive cooling, in actual operation, the coordinated operation of multiple devices may consume more energy.

[0006] Therefore, a new technical solution is needed to solve the above technical problems. Summary of the Utility Model

[0007] The present application provides a methanol energy-saving recovery device for sodium methoxide production, which includes a reaction tower, a rectification tower, a vacuum tower, a secondary pressurization tower, and a pressurization tower connected in sequence. A reaction tower reboiler is arranged in the bottom of the reaction tower. Reboilers for the rectification tower, the vacuum tower, the secondary pressurization tower, and the pressurization tower are respectively arranged at the lower parts of the rectification tower, the vacuum tower, the secondary pressurization tower, and the pressurization tower. Part of the refined methanol gas phase at the top of the rectification tower provides heat for the bottom of the reaction tower after being compressed, and part of the refined methanol gas phase provides heat for the rectification tower reboiler after being compressed; the refined methanol gas phase at the top of the secondary pressurization tower provides heat for the vacuum tower reboiler; the refined methanol gas phase at the top of the pressurization tower provides heat for the secondary pressurization tower reboiler.

[0008] As a preferred solution, the top of the rectification tower is connected to the bottom of the reaction tower through a first rectification tower gas pipeline. A first compressor is arranged on the first rectification tower gas pipeline. The first rectification tower gas pipeline is connected to a second rectification tower gas pipeline, and the second rectification tower gas pipeline is connected to the rectification tower reboiler. A second compressor is arranged on the second rectification tower gas pipeline.

[0009] As a preferred solution, the output end of the rectification tower reboiler is connected to the upper part of the rectification tower through a rectification tower reboiler output pipeline. A rectification tower cooler, a rectification tower reflux tank, and a reflux pump are sequentially arranged on the rectification tower reboiler output pipeline between the rectification tower reboiler and the rectification tower.

[0010] As a preferred solution, the top of the secondary pressurization tower is connected to the input end of the vacuum tower reboiler through a secondary pressurization tower top extraction pipeline.

[0011] As a preferred solution, the output end of the vacuum tower reboiler is connected to a secondary pressurization tower reflux device.

[0012] As a preferred solution, the secondary pressurization tower reflux device includes a secondary pressurization tower reflux tank. The bottom of the secondary pressurization tower reflux tank is connected to the secondary pressurization tower through a secondary pressurization tower reflux pipeline. The secondary pressurization tower reflux pipeline is connected to a secondary pressurization tower refined methanol extraction pipeline, and the secondary pressurization tower refined methanol extraction pipeline is connected to a methanol storage device.

[0013] As a preferred solution, the top of the pressurization tower is connected to the secondary pressurization tower reboiler through a pressurization tower top extraction pipeline.

[0014] As a preferred solution, the output end of the secondary pressurization tower reboiler is connected to a pressurization tower reflux device.

[0015] As a preferred solution, the pressurization tower reflux device includes a pressurization tower reflux tank. The bottom of the pressurization tower reflux tank is connected to the upper part of the pressurization tower through a pressurization tower reflux pipeline. The bottom of the pressurization tower reflux tank is also connected to a methanol storage device through a pressurization tower refined methanol extraction pipeline.

[0016] As a preferred solution, the bottom of the vacuum tower is connected to the secondary pressurizing tower through a vacuum tower bottom product pipeline, and a secondary pressurizing tower preheater is arranged on the vacuum tower bottom product pipeline; the refined methanol product pipeline of the pressurizing tower is connected to the input end and the output end of the secondary pressurizing tower preheater.

[0017] As a preferred solution, the top of the vacuum tower is connected to the vacuum tower reflux tank through a vacuum tower top product pipeline, a vacuum tower condenser is arranged on the vacuum tower top product pipeline, the bottom of the vacuum tower reflux tank is connected to the upper part of the vacuum tower through a vacuum tower reflux pipeline, the vacuum tower reflux pipeline is connected to the vacuum tower refined methanol product pipeline, and the vacuum tower refined methanol product pipeline is connected to the methanol storage device; a vacuum tower reflux tank gas pipeline is arranged at the top of the vacuum tower reflux tank, and a vacuum tower reflux tank gas phase condenser and a vacuum pump are arranged on the vacuum tower reflux tank gas pipeline.

[0018] As a preferred solution, the methanol storage device is connected to the distillation column through a reflux pipeline.

[0019] As a preferred solution, a pressurizing tower bottom product pipeline is arranged at the bottom of the pressurizing tower, the bottom of the secondary pressurizing tower is connected to the pressurizing tower through a secondary pressurizing tower bottom product pipeline, a pressurizing tower preheater is arranged on the pressurizing tower bottom product pipeline, and the pressurizing tower bottom product pipeline is connected to the input end and the output end of the pressurizing tower preheater.

[0020] The present application has the following advantages:

[0021] 1. Energy conservation and consumption reduction: The present invention significantly reduces the steam consumption in the rectification section (i.e., the distillation column), without consuming steam, only using electricity, which is suitable for areas where the steam price is high and the electricity price is low; for the recovery section, a three-tower three-effect process is adopted, namely a vacuum tower, a secondary pressurizing tower and a pressurizing tower. The steam at the top of the pressurizing tower heats the reboiler of the secondary pressurizing tower, and the steam at the top of the secondary pressurizing tower provides heat source for the reboiler of the vacuum tower. Only a small amount of steam is used in the pressurizing tower.

[0022] 2. Improving thermal efficiency: The present application effectively applies the methanol steam at the top of the distillation column to the reaction tower and the reboiler of its own distillation column, improving the thermal efficiency of the whole process.

[0023] 3. Optimizing the process flow: The present application realizes the optimization of the process flow by controlling the heat supply of the reaction tower and the distillation column, and the utilization of the methanol steam at the top of the secondary pressurizing tower and the pressurizing tower, reducing unnecessary energy consumption.

[0024] 4. Improving product purity: The purity of the refined methanol obtained at the top of the distillation column is as high as ≥99.99%, ensuring the high quality of the product.

[0025] 5. Reduction of comprehensive energy consumption: Compared with the currently advanced three-tower two-heat pump process, this application significantly reduces the steam specific consumption of the entire process, which is 0.62 tons of steam per ton of sodium methoxide, effectively reducing the overall energy consumption (Note: 1 kWh of electricity is equivalent to 0.123 kg of standard coal or 0.0013 tons of steam).

[0026] 6. Environmental benefits: By reducing steam consumption and optimizing energy utilization, it helps to reduce greenhouse gas emissions and has positive environmental benefits. Brief Description of the Drawings

[0027] Figure 1 is a schematic structural diagram of this application;

[0028] 1. Reaction tower; 2. Rectification tower; 3. Vacuum tower; 4. Secondary pressurization tower; 5. Pressurization tower; 6. Feed pipeline; 7. Feed preheater for reaction tower; 8. Overhead product pipeline of reaction tower; 9. Bottom product pipeline of reaction tower; 10. Flash tank; 11. Sodium methoxide product pipeline; 12. Solid sodium methoxide finished product pump; 13. Gas pipeline of flash tank; 14. Condenser; 15. Bottom product pipeline one of reaction tower; 16. Cooler; 17. Intermediate tank; 18. Methanol product pipeline; 19. Methanol transfer pump; 20. Bottom product pipeline of rectification tower; 21. Reboiler circulation pump; 22. Intermediate tank of rectification tower; 23. Bottom pump of rectification tower; 24. Tail gas pipeline; 25. Bottom product pipeline of vacuum tower; 26. Feed pump for secondary pressurization tower; 27. Preheater for secondary pressurization tower; 28. Bottom product pipeline of secondary pressurization tower; 29. Feed pump for pressurization tower; 30. Preheater for pressurization tower; 31. Bottom product pipeline of pressurization tower; 32. Waste water pump; 33. Waste water cooler; 34. Reboiler of reaction tower; 35. Reboiler of rectification tower; 36. Reboiler of vacuum tower; 37. Reboiler of secondary pressurization tower; 38. Reboiler of pressurization tower; 39. Gas pipeline one of rectification tower; 40. Compressor one; 41. Gas pipeline two of rectification tower; 42. Compressor two; 43. Output pipeline of rectification tower reboiler; 44. Cooler of rectification tower; 45. Reflux drum of rectification tower; 46. Reflux pump; 47. Overhead product pipeline of vacuum tower; 48. Reflux drum of vacuum tower; 49. Condenser of vacuum tower; 50. Reflux pipeline of vacuum tower; 51. Reflux pump of vacuum tower; 52. Refined methanol product pipeline of vacuum tower; 53. Methanol storage device; 54. Gas pipeline of reflux drum of vacuum tower; 55. Gas condenser of reflux drum of vacuum tower; 56. Vacuum pump; 57. Overhead product pipeline of secondary pressurization tower; 58. Output pipeline of vacuum tower reboiler; 59. Reflux drum of secondary pressurization tower; 60. Reflux pipeline of secondary pressurization tower; 61. Reflux pump of secondary pressurization tower; 62. Refined methanol product pipeline of secondary pressurization tower; 63. Cooler of secondary pressurization tower; 64. Overhead product pipeline of pressurization tower; 65. Output pipeline of secondary pressurization tower reboiler; 66. Reflux drum of pressurization tower; 67. Reflux pipeline of pressurization tower; 68. Reflux pump of pressurization tower; 69. Refined methanol product pipeline of pressurization tower; 70. Cooler of pressurization tower; 71. Reflux pipeline; 72. Reflux pump one; 73. Steam reboiler of rectification tower; 74. Steam reboiler of vacuum tower; 75. Steam reboiler of secondary pressurization tower. Detailed implementation manners

[0029] The following combines the appended Figure 1 The detailed implementation manners of the present utility model will be described in detail. It should be noted that the detailed implementation manners described herein are only used to illustrate and explain the present utility model, and are not used to limit the present utility model.

[0030] Example 1:

[0031] This embodiment provides a methanol energy-saving recovery device for sodium methoxide production, which includes a reaction tower 1, a rectification tower 2, a vacuum tower 3, a secondary pressurization tower 4, and a pressurization tower 5 connected in sequence. The temperature at the top of the reaction tower 1 is 85°C, and the pressure is 130 KPa; the temperature at the top of the rectification tower 2 is 65°C, and the pressure is 103 KPa. The mass flow rate of the substance flowing out from the top of the rectification tower per unit time is 32,047 Kg / h; the temperature at the top of the vacuum tower 3 is 54°C, and the pressure is 65 kpa. The temperature at the bottom of the vacuum tower 3 is 63.6°C, and the pressure is 70 kpa; the temperature at the top of the secondary pressurization tower 4 is 77.4°C, and the pressure is 165 kpa. The temperature at the bottom of the secondary pressurization tower 4 is 90.7°C, and the pressure is 169 kpa; One side of the reaction tower 1 is connected to a feed pipeline 6. A reaction tower feed preheater 7 is arranged on the feed pipeline 6. The material at about 40°C is heated to 60°C - 80°C by the reaction tower feed preheater 7 and then enters the reaction tower 1. The reaction tower feed preheater 7 is heated by steam; The top of the reaction tower 1 is connected to the rectification tower 2 through a reaction tower top product pipeline 8. The methanol water vapor extracted from the top of the reaction tower 1 enters the rectification tower 2 for distillation; The bottom of the reaction tower 1 is connected to a reaction tower bottom product pipeline 9. The reaction tower bottom product pipeline 9 is connected to a flash tank 10. The bottom of the flash tank 10 is connected to a sodium methoxide product pipeline 11. A solid sodium methoxide finished product pump 12 is arranged on the sodium methoxide product pipeline 11. A flash tank gas phase pipeline 13 is arranged at the top of the flash tank 10. A condenser 14 is arranged on the flash tank gas phase pipeline 13; The reaction tower bottom product pipeline 9 is connected to a reaction tower bottom product pipeline 15. A cooler 16 is arranged on the reaction tower bottom product pipeline 15. The reaction tower bottom product pipeline 15 is connected to an intermediate tank 17. A methanol extraction pipeline 18 is arranged at the bottom of the intermediate tank 17. A methanol transfer pump 19 is arranged on the methanol extraction pipeline 18; The reaction tower bottom extracts a mixed solution of 30% sodium methoxide and methanol at 105°C, which enters the flash tank 10 through the reaction tower bottom product pipeline 9. The solid sodium methoxide after flashing in the flash tank 10 is transported to the solid workshop through the sodium methoxide product pipeline 11, etc. The flashed methanol vapor is condensed by the condenser 14 and then sent to the alkali preparation tank to recover the methanol therein, realizing the recycling of resources, reducing production costs. In addition, through condensation recovery, the emission of methanol can be reduced, meeting the environmental protection requirements; The reaction tower bottom extracts a mixed solution of 30% sodium methoxide and methanol at 105°C, enters the reaction tower bottom product pipeline 15, is cooled by the cooler 16 and then enters the intermediate tank 17 for buffering. The liquid-phase methanol in the intermediate tank 17 is extracted through the methanol extraction pipeline 18 and sent to the tank area.

[0032] The bottom of the rectification column 2 is connected to the vacuum column 3 through the rectification column bottom product pipeline 20. A reboiler circulation pump 21, a rectification column intermediate tank 22, and a rectification column bottom pump 23 are successively arranged on the rectification column bottom product pipeline 20. The reboiler circulation pump 21 is used to ensure that there is always sufficient fluid flow in the rectification column reboiler 35 to guarantee the normal operation of the rectification column reboiler 35. The rectification column intermediate tank 22 is connected to the tail gas pipeline 24. After the methanol aqueous solution generated by the tail gas and the methanol aqueous solution drawn from the bottom of the rectification column 2 are mixed in the rectification column intermediate tank 22, they enter the vacuum column 3.

[0033] The bottom of the vacuum column 3 is connected to the secondary pressurization column 4 through the vacuum column bottom product pipeline 25. A secondary pressurization column feed pump 26 and a secondary pressurization column preheater 27 are arranged on the vacuum column bottom product pipeline 25. The material drawn from the vacuum column 3 is preheated to about 75 °C by the secondary pressurization column preheater 27 and then enters the secondary pressurization column 4.

[0034] The bottom of the secondary pressurization column 4 is connected to the pressurization column 5 through the secondary pressurization column bottom product pipeline 28. A pressurization column feed pump 29 and a pressurization column preheater 30 are arranged on the secondary pressurization column bottom product pipeline 28. The material about 90.7 °C drawn from the bottom of the secondary pressurization column 4 is preheated to about 115 °C by the secondary pressurization column preheater 27 and then enters the pressurization column 5.

[0035] A pressurization column bottom product pipeline 31 is arranged at the bottom of the pressurization column 5. The pressurization column bottom product pipeline 31 is used to draw out wastewater. A wastewater pump 32 and a wastewater cooler 33 are arranged on the pressurization column bottom product pipeline 31. The temperature of the bottom of the pressurization column 5 is 143 °C, and the mass flow rate of the substance flowing out of the bottom of the pressurization column 5 per unit time is 298 Kg / h. The pressurization column bottom product pipeline 31 passes through the pressurization column preheater 30, that is, the pressurization column bottom product pipeline 31 is connected to the input end and the output end of the pressurization column preheater 30. The material drawn from the bottom of the pressurization column 5 is heated and cooled to 99 °C by the pressurization column preheater 30, and then cooled to 45 °C by the wastewater cooler 33 and discharged. Using the heat of the wastewater at the bottom of the pressurization column 5 to supply heat to the pressurization column preheater 30 improves the utilization rate of heat and reduces the consumption of steam.

[0036] A reaction column reboiler 34 is arranged in the bottom of the reaction column 1. The reaction column reboiler 34 preferably adopts a coil reboiler. When the reaction heat of the reaction column 1 is insufficient, heat is supplemented by steam. By precisely controlling the coil reboiler at the bottom of the reaction column 1, the effective supplement of the reaction heat of the reaction column 1 is realized, and the steam consumption is reduced. The lower parts of the rectification column 2, the vacuum column 3, the secondary pressurization column 4, and the pressurization column 5 are respectively provided with a rectification column reboiler 35, a vacuum column reboiler 36, a secondary pressurization column reboiler 37, and a pressurization column reboiler 38. Among them, the rectification column reboiler 35 preferably adopts a falling film reboiler. The pressurization column reboiler 38 uses steam for heating, and the pressure of the steam is preferably 5 bar.

[0037] The top of the rectification column 2 is connected to the bottom of the reaction column 1 through the first rectification column gas pipeline 39, and a first compressor 40 is provided on the first rectification column gas pipeline 39; a part of the refined methanol gas phase at the top of the rectification column 2 provides heat for the bottom of the reaction column 1 after being compressed and heated by the first compressor 40. That is, the heat of the reaction column 1 mainly comes from the steam of methanol at the top of the rectification column 2. This steam is pressurized to 153 kPa by the first compressor 40 and heated to 90 - 105 °C. The mass flow rate of the refined methanol flowing out of the first rectification column gas pipeline 39 per unit time is 14,567 kg / h, and the purity of the refined methanol is 99.99%. It serves as both a heat source and promotes the reaction of methanol and alkali in the direction of forming sodium methoxide; the first rectification column gas pipeline 39 is connected to a second rectification column gas pipeline 41, the second rectification column gas pipeline 41 is connected to the rectification column reboiler 35, a second compressor 42 is provided on the second rectification column gas pipeline 41, the output end of the rectification column reboiler 35 is connected to the upper part of the rectification column 2 through the rectification column reboiler output pipeline 43, and a rectification column cooler 44, a rectification column reflux drum 45, and a reflux pump 46 are sequentially arranged on the rectification column reboiler output pipeline 43 between the rectification column reboiler 35 and the rectification column 2; a part of the refined methanol gas phase at the top of the rectification column 2 is pressurized to 203 kPa by the second compressor 42 and heated to 128 °C. The mass flow rate of the refined methanol flowing out of the second rectification column gas pipeline 41 per unit time is 17,480 kg / h, and the purity of the refined methanol is 99.99%. After being compressed and heated, it provides heat for the rectification column reboiler 35 to meet the heat demand of the rectification column reboiler 35. The steam that is heat-exchanged and condensed by the rectification column reboiler 35 has a temperature of 46 °C and a pressure of 403 kPa in the rectification column reboiler output pipeline 43 after passing through the rectification column cooler 44, the rectification column reflux drum 45, and the reflux pump 46. The mass flow rate of the refined methanol flowing out of the rectification column reboiler output pipeline 43 is 17,480 kg / h, and the purity of the refined methanol is 99.99%; the refined methanol in the rectification column reboiler output pipeline 43 flows back to the top of the rectification column 2, so that the purity of the refined alcohol obtained at the top of the rectification column 2 reaches ≥99.99%, while the bottom of the rectification column 2 produces an aqueous methanol solution, which is sent to the negative pressure column 3 for methanol recovery.

[0038] In order to improve the precision of methanol, the top of the vacuum tower 3 is connected to the vacuum tower reflux drum 48 through the vacuum tower top draw pipeline 47. A vacuum tower condenser 49 is provided on the vacuum tower top draw pipeline 47. The bottom of the vacuum tower reflux drum 48 is connected to the upper part of the vacuum tower 3 through the vacuum tower reflux pipeline 50. A vacuum tower reflux pump 51 is provided on the vacuum tower reflux pipeline 50. The vacuum tower reflux pipeline 50 is connected to the vacuum tower refined methanol draw pipeline 52, and the vacuum tower refined methanol draw pipeline 52 is connected to the methanol storage device 53. A vacuum tower reflux drum gas pipeline 54 is provided at the top of the vacuum tower reflux drum 48. A vacuum tower reflux drum gas phase condenser 55 and a vacuum pump 56 are provided on the vacuum tower reflux drum gas pipeline 54. The reflux liquid in the vacuum tower 3 flows downward from the tower top and exchanges heat and mass with the rising steam, thereby further separating different components in the rising steam. By adjusting the reflux ratio, the separation effect of the vacuum tower 3 can be controlled to make the methanol product reach the required purity. In this embodiment, the temperature of the methanol solution in the vacuum tower reflux pipeline 50 is 49°C, and the reflux ratio is 1.

[0039] The top of the secondary pressurizing tower 4 is connected to the input end of the vacuum tower reboiler 36 through the secondary pressurizing tower top draw pipeline 57. The output end of the vacuum tower reboiler 36 is connected to the secondary pressurizing tower reflux device through the vacuum tower reboiler output pipeline 58. The secondary pressurizing tower reflux device includes a secondary pressurizing tower reflux drum 59, and the secondary pressurizing tower reflux drum 59 is connected to the vacuum tower reboiler output pipeline 58. The bottom of the secondary pressurizing tower reflux drum 59 is connected to the secondary pressurizing tower 4 through the secondary pressurizing tower reflux pipeline 60. A secondary pressurizing tower reflux pump 61 is provided on the secondary pressurizing tower reflux pipeline 60. The temperature of the refined methanol in the secondary pressurizing tower reflux pipeline 60 is 77.4°C. The reflux ratio at the top of the secondary pressurizing tower 4 is 1.15. The secondary pressurizing tower reflux pipeline 60 is connected to the secondary pressurizing tower refined methanol draw pipeline 62. The temperature of the methanol in the secondary pressurizing tower refined methanol draw pipeline 62 is 77.4°C. The mass flow rate of the refined methanol flowing out of the secondary pressurizing tower refined methanol draw pipeline 62 per unit time is 297 kg / h. A secondary pressurizing tower cooler 63 is provided on the secondary pressurizing tower refined methanol draw pipeline 62. The secondary pressurizing tower refined methanol draw pipeline 62 is connected to the methanol storage device 53. The refined methanol gas phase at the top of the secondary pressurizing tower 4 provides heat for the vacuum tower reboiler 36 to achieve efficient recovery and utilization of heat energy. The refined methanol gas phase after heat exchange and cooling flows back to the secondary pressurizing tower reflux drum 59. Part of the refined methanol in the secondary pressurizing tower reflux drum 59 flows back to the secondary pressurizing tower 4, and part is cooled to 50°C and then taken out as refined methanol.

[0040] The top of the pressurized tower 5 is connected to the reboiler 37 of the secondary pressurized tower through the overhead product pipeline 64 of the pressurized tower. The output end of the reboiler 37 of the secondary pressurized tower is connected to the reflux device of the pressurized tower through the output pipeline 65 of the reboiler of the secondary pressurized tower. The reflux device of the pressurized tower includes a reflux drum 66 of the pressurized tower connected to the output pipeline 65 of the reboiler of the secondary pressurized tower. The bottom of the reflux drum 66 of the pressurized tower is connected to the upper part of the pressurized tower 5 through the reflux pipeline 67 of the pressurized tower. The temperature of the refined methanol in the reflux pipeline 67 of the pressurized tower is 103 °C, and the reflux ratio at the top of the pressurized tower 5 is 1.6. A reflux pump 68 of the pressurized tower is provided on the reflux pipeline 67 of the pressurized tower. The bottom of the reflux drum 66 of the pressurized tower is also connected to the methanol storage device 53 through the refined methanol extraction pipeline 69 of the pressurized tower. The temperature of the methanol in the refined methanol extraction pipeline 69 of the pressurized tower is 103 °C, and the mass flow rate of the refined methanol flowing out of the refined methanol extraction pipeline 69 of the pressurized tower per unit time is 280 kg / h. A cooler 70 of the pressurized tower is provided on the refined methanol extraction pipeline 69 of the pressurized tower. The refined methanol gas phase at the top of the pressurized tower 5 provides heat for the reboiler 37 of the secondary pressurized tower, realizing the efficient recovery and utilization of thermal energy. After heat exchange and cooling, the refined methanol gas phase returns to the reflux drum 66 of the pressurized tower. Part of the refined methanol in the reflux drum 66 of the pressurized tower returns to the pressurized tower 5, and part of it is cooled to 50 °C and then taken out as refined methanol.

[0041] Preferably, in this embodiment, the extracted refined methanol can also be directly utilized to promote the reaction in the rectification tower 2. The methanol storage device 53 is connected to the rectification tower 2 through a reflux pipeline 71, and a first reflux pump 72 is provided on the reflux pipeline 71. The temperature in the reflux pipeline 71 is 50 °C, the mass flow rate of the refined methanol flowing out of the reflux pipeline 71 is 902 kg / h, and the purity of the methanol solution is 99.99%. The above-mentioned negative pressure tower refined methanol extraction pipeline 52, the secondary pressurized tower refined methanol extraction pipeline 62, and the pressurized tower refined methanol extraction pipeline 69 can be respectively connected to the methanol storage device 53, or they can be mixed first and then connected to the methanol storage device 53. For example, the secondary pressurized tower refined methanol extraction pipeline 62 and the pressurized tower refined methanol extraction pipeline 69 are not directly connected to the methanol storage device 53, but are connected to the negative pressure tower refined methanol extraction pipeline 52.

[0042] Preferably, a rectification column steam reboiler 73 is provided at the lower part of the rectification column 2, and the rectification column steam reboiler 73 is heated by steam; a vacuum column steam reboiler 74 is provided at the lower part of the vacuum column 3, and the vacuum column steam reboiler 74 is heated by steam; a secondary pressurization column steam reboiler 75 is provided at the lower part of the secondary pressurization column 4, and the secondary pressurization column steam reboiler 75 is heated by steam; the rectification column steam reboiler 73, the vacuum column steam reboiler 74, and the secondary pressurization column steam reboiler 75 are only used during the start-up phase or when the equipment is unstable. After start-up, the steam at the top of the rectification column 2 is pressurized and heated by the first compressor 40 and the second compressor 42, and respectively provides heat for the bottom of the reaction column 1 and the rectification column reboiler 35. The refined methanol steam at the top of the secondary pressurization column 4 provides heat for the vacuum column reboiler 36, and the refined methanol steam at the top of the pressurization column 5 provides heat for the secondary pressurization column reboiler 37. Only the pressurization column reboiler 38 requires steam heating, and the rest do not require additional steam supply, achieving self-sufficiency in the vast majority of heat.

[0043] In this embodiment, a coupling mode of the vacuum column 3, the secondary pressurization column 4, and the pressurization column 5 is adopted. The refined methanol steam at the top of the secondary pressurization column 4 provides heat for the vacuum column reboiler 36, and the refined methanol steam at the top of the pressurization column 5 provides heat for the secondary pressurization column reboiler 37; by recycling the methanol steam between the columns, the steam consumption is significantly reduced; in this mode, the steam consumption per ton of refined alcohol in the vacuum column 3, the secondary pressurization column 4, and the pressurization column 5 is only 0.33 tons.

[0044] This application has the following advantages:

[0045] 1. Energy conservation and consumption reduction: The present invention significantly reduces the steam consumption in the rectification section, without consuming steam and only using electricity, which is suitable for areas where the steam price is high and the electricity price is low; for the recovery section, a three-column and three-effect process is adopted, namely, a vacuum column, a secondary pressurization column, and a pressurization column. The steam at the top of the pressurization column heats the secondary pressurization column reboiler, and the steam at the top of the secondary pressurization column provides heat for the vacuum column reboiler. Only a small amount of steam is used in the pressurization column;

[0046] 2. Improving thermal efficiency: This application effectively applies the methanol steam at the top of the rectification column to the reaction column and its own rectification column reboiler, improving the thermal efficiency of the entire process;

[0047] 3. Optimizing the process flow: This application realizes the optimization of the process flow by controlling the heat supply of the reaction column and the rectification column, as well as the utilization of the methanol steam at the tops of the secondary pressurization column and the pressurization column, reducing unnecessary energy consumption;

[0048] 4. Improving product purity: The purity of the refined alcohol obtained at the top of the rectification column is as high as ≥99.99%, ensuring the high quality of the product;

[0049] 5. Reduction of comprehensive energy consumption: Compared with the currently more advanced three-column two-heat pump process, the present application significantly reduces the steam specific consumption of the whole process, which is 0.62 tons of steam per ton of sodium methoxide, effectively reducing the overall energy consumption (Note: 1 kWh of electricity is equivalent to 0.123 kg of standard coal or 0.0013 tons of steam).

[0050] 6. Environmental protection benefits: By reducing steam consumption and optimizing energy utilization, it helps to reduce greenhouse gas emissions and has positive environmental protection benefits.

[0051] 7. The equipment adopts mature reaction towers, distillation towers, vacuum towers, secondary pressurization towers, and pressurization towers with simple structures, thereby making the installation, commissioning, and maintenance of the equipment less difficult; mature equipment is not prone to failures, ensuring the stability and continuity of production.

[0052] The preferred embodiments of the present application have been 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 scope of the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, and these simple modifications all fall within the protection scope of the present application.

[0053] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any suitable manner. To avoid unnecessary repetition, various possible combination methods of the present application will not be described separately.

[0054] Furthermore, any combination can be made between various different embodiments of the present application as long as it does not violate the idea of the present application, and it should also be regarded as the content disclosed in the present application.

Claims

1. A methanol energy-saving recovery device for sodium methoxide production, characterized in that: The invention comprises a reaction tower (1), a distillation tower (2), a negative pressure tower (3), a secondary pressure tower (4), and a pressure tower (5) which are connected in sequence, wherein a reaction tower reboiler (34) is arranged in the tower kettle of the reaction tower (1), and a distillation tower reboiler (35), a negative pressure tower reboiler (36), a secondary pressure tower reboiler (37), and a pressure tower reboiler (38) are arranged at the lower parts of the distillation tower (2), the negative pressure tower (3), the secondary pressure tower (4), and the pressure tower (5), respectively, wherein part of the refined methanol gas phase at the top of the distillation tower (2) is compressed to provide heat for the tower kettle of the reaction tower (1), and part of the refined methanol gas phase is compressed to provide heat for the distillation tower reboiler (35); and the refined methanol gas phase at the top of the secondary pressure tower (4) provides heat for the negative pressure tower reboiler (36); The refined methanol gas phase at the top of the pressure tower (5) provides heat for the reboiler (37) of the secondary pressure tower.

2. A methanol energy-saving recovery device for sodium methoxide production according to claim 1, characterized in that: The top of the distillation tower (2) is connected to the bottom of the reaction tower (1) via a distillation tower gas phase pipeline 1 (39); a compressor 1 (40) is provided on the distillation tower gas phase pipeline 1 (39); the distillation tower gas phase pipeline 1 (39) is connected to a distillation tower gas phase pipeline 2 (41); the distillation tower gas phase pipeline 2 (41) is connected to a distillation tower reboiler (35); and a compressor 2 (42) is provided on the distillation tower gas phase pipeline 2 (41).

3. A methanol energy-saving recovery device for sodium methoxide production according to claim 2, characterized in that: The output end of the distillation tower reboiler (35) is connected to the upper part of the distillation tower (2) through the distillation tower reboiler output pipeline (43), and a distillation tower cooler (44), a distillation tower reflux tank (45), and a reflux pump (46) are sequentially arranged on the distillation tower reboiler output pipeline (43) between the distillation tower reboiler (35) and the distillation tower (2).

4. A methanol energy-saving recovery device for sodium methoxide production according to claim 1, characterized in that: The top of the secondary pressure tower (4) is connected to the input end of the negative pressure tower reboiler (36) through the secondary pressure tower top extraction pipeline (57), and the output end of the negative pressure tower reboiler (36) is connected to the secondary pressure tower reflux device.

5. A methanol energy-saving recovery device for sodium methoxide production according to claim 4, characterized in that: The secondary pressure tower reflux device comprises a secondary pressure tower reflux tank (59), the bottom of which is connected to the secondary pressure tower (4) via a secondary pressure tower reflux pipeline (60), the secondary pressure tower reflux pipeline (60) is connected to a secondary pressure tower refined methanol extraction pipeline (62), and the secondary pressure tower refined methanol extraction pipeline (62) is connected to a methanol storage device (53).

6. A methanol energy-saving recovery device for sodium methoxide production according to claim 1, characterized in that: The top of the pressure tower (5) is connected to the input end of the secondary pressure tower reboiler (37) through the pressure tower top extraction pipeline (64), and the output end of the secondary pressure tower reboiler (37) is connected to the pressure tower reflux device.

7. A methanol energy-saving recovery device for sodium methoxide production according to claim 6, characterized in that: The pressurized tower reflux device comprises a pressurized tower reflux tank (66), the bottom of which is connected to the upper part of the pressurized tower (5) via a pressurized tower reflux pipeline (67), and the bottom of which is also connected to a methanol storage device (53) via a pressurized tower refined methanol extraction pipeline (69).

8. A methanol energy-saving recovery device for sodium methoxide production according to claim 7, characterized in that: The bottom of the negative pressure tower (3) is connected to the secondary pressure tower (4) via a negative pressure tower kettle extraction pipeline (25), a secondary pressure tower preheater (27) is provided on the negative pressure tower kettle extraction pipeline (25), and the pressure tower refined methanol extraction pipeline (69) is connected to the input end and the output end of the secondary pressure tower preheater (27).

9. A methanol energy-saving recovery device for sodium methoxide production according to claim 1, characterized in that: The top of the negative pressure tower (3) is connected to the negative pressure tower reflux tank (48) through a negative pressure tower top extraction pipeline (47), and a negative pressure tower condenser (49) is arranged on the negative pressure tower top extraction pipeline (47). The bottom of the negative pressure tower reflux tank (48) is connected to the upper part of the negative pressure tower (3) through a negative pressure tower reflux pipeline (50), and the negative pressure tower reflux pipeline (50) is connected to a negative pressure tower refined methanol extraction pipeline (52), and the negative pressure tower refined methanol extraction pipeline (52) is connected to a methanol storage device (53); a negative pressure tower reflux tank gas phase pipeline (54) is arranged on the top of the negative pressure tower reflux tank (48), and a negative pressure tower reflux tank gas phase condenser (55) and a vacuum pump (56) are arranged on the negative pressure tower reflux tank gas phase pipeline (54).

10. A methanol energy-saving recovery device for sodium methoxide production according to any one of claims 5, 7 and 9, characterized in that: The methanol storage device (53) is connected to the distillation tower (2) via a reflux line (71).

Images