Multi-effect energy-saving methanol rectification device

Abstract

The utility model provides a multi-effect energy-saving methanol rectification device which can greatly reduce the operation energy consumption. The whole device at least comprises five towers including a light component removal tower (T300), a first rectifying tower (T310), a second rectifying tower (T320), a third rectifying tower (T330) and a fourth rectifying tower (T340) and matched equipment thereof. The method can be used for recovery of various methanol solvents and rectification processes of methanol synthesis devices to produce national standard superior methanol, American standard AA-grade methanol products or methanol products of other specifications. The defects in the prior art are overcome, the unit steam consumption of the refined methanol product can be reduced to below 0.48, and the method has remarkable practicability and economic benefits and wide application prospects.

Description

Technical Field

[0001] This utility model provides a multi-effect energy-saving methanol distillation device, which can be used in the distillation process of various methanol solvent recovery and methanol synthesis devices to produce high-quality methanol products. Background Technology

[0002] Methanol is an important organic chemical raw material and a new type of energy fuel, with wide applications in the chemical, light industry, and clean energy sectors. In the industrial production of synthetic methanol, the energy consumption of the crude methanol refining process is one of the key factors affecting the production cost.

[0003] Figure 1 This is a widely used four-tower (three towers plus one tower) methanol distillation process, employing three towers (pre-tower T101, pressurized tower T102, and first distillation tower T103) plus a recovery tower T104 to produce national standard superior grade or US standard AA grade methanol. Light components are removed from the top of the pre-tower. The pre-crude methanol 10 is then distilled in the pressurized tower and the first distillation tower. Methanol products are obtained from the top discharge 24 of the pressurized tower and the top discharge 14 of the first distillation tower, respectively. Fusel oil 42 is extracted from the side stream of the first distillation tower. The vapor phase 21 from the top of the pressurized tower is used to heat the bottom of the first distillation tower. The fusel oil 42 and the bottom liquid 15 from the first distillation tower are fed into the recovery tower. Recovered methanol product 29 is obtained from the top of the recovery tower. Fusel oil oil 30 is extracted from the side stream of the recovery tower, and wastewater 33 is discharged from the bottom of the recovery tower. Although this method is technically mature, it has high energy consumption, and with the increasing scale of the plant, its equipment is quite large. This is detrimental to the construction and stable economic operation of increasingly large-scale methanol production facilities.

[0004] Chinese patent CN 201420664698.2 discloses a process method for a "flexible methanol distillation device capable of producing both MTO-grade and AA-grade methanol." Its core content is based on the widely used four-tower double-effect distillation process, utilizing the condensate heat of heating steam or heat exchange between hot and cold liquids within the system to achieve energy savings. Clearly, this sensible heat transfer between materials has a very limited effect on reducing the overall operating energy consumption of the distillation system.

[0005] CN 201910655239.5 discloses an "Improved Three-Tower Three-Effect Crude Methanol Refining Process," characterized by: increasing the operating pressure of the first and second distillation columns, enabling the first, second, and pre-distillation columns to operate under a three-effect thermal integration. A portion of the vapor phase from the top of the second distillation column is separated to provide heat to the pre-distillation column. Compared to CN201420664698.2, this process has a higher energy-saving effect. However, since the pre-distillation column does not produce methanol at its top, the energy provided by the second distillation column to the pre-distillation column is a single-effect methanol distillation process. While both the first and second distillation columns produce methanol at their tops, only the energy provided by the first distillation column to the second distillation column is a double-effect methanol distillation process. Therefore, although this process has some improvement in energy saving, the energy-saving effect is not ideal.

[0006] CN201711022448.3 discloses a "Methanol Three-Effect Distillation System and Process," and CN 201811025624.3 discloses a "Vacuum Thermally Coupled Methanol Distillation Method and Apparatus." Both patents employ a three-effect thermally integrated operation for the methanol-producing distillation column within the system, with the lowest operating pressure being a vacuum distillation column. Vacuum distillation columns are advantageous for increasing the relative volatility of the separation system and obtaining higher methanol product purity. However, the pre-distillation columns in both patented processes still use fresh steam heating and are not thermally integrated with the methanol distillation column, thus limiting their energy-saving effects.

[0007] CN200910068170.2 describes a process for methanol distillation using a five-tower thermal integration unit. The crude methanol from the bottom of the pre-distillation tower first enters the atmospheric distillation tower. The bottom material from the atmospheric distillation tower then enters the low-pressure distillation tower, and the bottom material from the low-pressure distillation tower enters the high-pressure distillation tower. Methanol products are collected from the tops of the atmospheric, low-pressure, and high-pressure distillation towers, respectively. The bottom material from the high-pressure distillation tower enters the recovery tower. The atmospheric, low-pressure, and high-pressure distillation towers are integrated with a triple-effect thermal integration, while the pre-distillation and recovery towers are integrated with a double-effect thermal integration. However, the energy consumption of this process is still relatively high, and there is room for optimization and reduction.

[0008] CN202110667709.7 describes a process for methanol distillation using a five-tower double triple-effect thermal integration unit. The light-light removal tower (T210), the first distillation tower (T220), the second distillation tower (T230), the third distillation tower (T240), and the final tower (T250) are operated in a double triple-effect thermal integration manner. Compared with the triple-effect + double-effect process provided by CN200910068170.2, the operating energy consumption of this process is reduced, but there is still room for further reduction in energy consumption.

[0009] CN202321881315.2 discloses "a five-tower four-effect crude methanol refining device", and CN202310877978.5 discloses "a five-tower four-effect crude methanol refining process and device". The methanol refining process is essentially a three-effect thermal integrated distillation process: the main body of the pre-distillation tower (1) is heated by fresh steam, and the sensible heat of the condensate at the top of the pressurized distillation tower (3) is used to heat the pre-distillation tower. The effective heat of this part is relatively small. Therefore, the pressurized distillation tower only provides a small amount of heat to the pre-distillation tower. The pressurized distillation tower (3), the atmospheric distillation tower (4), and the negative pressure distillation tower (2) adopt three-effect thermal integrated operation. The pre-distillation tower and the negative pressure distillation tower adopt double-effect thermal integrated operation. The recovery tower (5) and the pressurized distillation tower (3) are also heated by fresh steam. The energy consumption of this process is relatively high, and the steam consumption of refined methanol product is ~0.62.

[0010] CN202310877976.6 discloses "a five-tower four-effect crude methanol refining process and equipment". The methanol refining process is essentially a three-effect thermal integrated distillation process: the main body of the pre-distillation tower (1) is heated by the pressurized gas phase after being compressed by the heat pump (60) after the gas phase collected from its top is taken out. In addition, the sensible heat of the condensate at the top of the pressurized distillation tower (3) is used to heat the pre-distillation tower. The effective heat of this part is relatively small. Therefore, the pressurized distillation tower only provides a small amount of heat to the pre-distillation tower. The pressurized distillation tower (3), the atmospheric distillation tower (4), and the negative pressure distillation tower (2) adopt a three-effect thermal integrated operation. At the same time, the negative pressure distillation tower is also supplemented with fresh steam heating. The recovery tower (5) and the pressurized distillation tower (3) are also heated with fresh steam. Although the steam consumption of the refined methanol product is ~0.5, the use of heat pump technology greatly increases the power consumption.

[0011] CN202110620943.4 discloses "a multi-effect methanol refining device and its refining process," in which the pressure of the first pressurized distillation column, the second pressurized distillation column, the third pressurized distillation column, and the atmospheric distillation column decreases sequentially, and a four-effect thermal integration operation is adopted. The first pressurized distillation column is heated by fresh steam, and the bottom of the atmospheric distillation column is drained. The pre-distillation column is heated by fresh steam and is a single-effect operation, not participating in the thermal integration operation. The top pressure of the first pressurized distillation column is 25-35 bar, which is a very high operating pressure. The process has high energy consumption, with a single steam consumption of ~0.8 for refined methanol product.

[0012] CN201910748405.6 discloses "a single-tower steam-driven methanol six-tower four-effect distillation method without by-product fusel oil". The methanol refining process is essentially a four-effect + three-effect thermal integrated distillation process: four-effect thermal integration between vacuum tower (7), atmospheric tower (10), medium-pressure tower (12), and high-pressure tower (14); three-effect thermal integration between vacuum tower (7), pre-separation tower (1), and high-pressure tower (14); only fuel alcohol is produced at the top of the recovery tower; the methanol yield is low, the energy saving effect is poor, and there is still a lot of room for optimization. Summary of the Invention

[0013] The purpose of this invention is to provide a multi-effect, energy-saving methanol distillation apparatus. It belongs to the category of five-tower, double-four-effect, thermally integrated distillation process devices, overcoming the shortcomings of existing technologies. The steam consumption per unit volume of refined methanol can be reduced to below 0.48, demonstrating significant practicality and economic benefits, with broad application prospects. It can substantially reduce operating energy consumption. It can be used in the distillation processes of various methanol solvent recovery and methanol synthesis units to produce national standard superior-grade methanol, US standard AA-grade methanol, or other specifications of methanol products.

[0014] The present invention provides a multi-effect energy-saving methanol distillation apparatus, which mainly includes the following steps:

[0015] 1) It includes at least five distillation towers: T300 (light component removal tower), T310 (first distillation tower), T320 (second distillation tower), T330 (third distillation tower), and T340 (fourth distillation tower).

[0016] 2) After preheating, crude methanol enters the light component removal tower T300, and the liquid phase from the bottom of the light component removal tower T300 enters the first distillation tower T310.

[0017] 3) The liquid phase from the bottom of the first distillation column T310 enters the second distillation column T320.

[0018] 4) The liquid phase from the bottom of the second distillation column T320 enters the third distillation column T330.

[0019] 5) The liquid phase from the bottom of the third distillation column T330 enters the fourth distillation column T340.

[0020] 6) The five distillation columns are integrated using a double quadruple-effect heat exchanger. The vapor phase from the top of the fourth distillation column T340 serves as the heat source for the bottom of the third distillation column T330, providing the required heat for the third distillation column T330. The vapor phase from the top of the third distillation column T330 serves as the heat source for the bottom of the light component removal column T300 and the second distillation column T320, providing the required heat for the light component removal column T300 and the second distillation column T320. The vapor phase from the top of the light component removal column T300 serves as the heat source for the feed preheater of the first distillation column T310, providing part of the required heat for the first distillation column T310. The vapor phase from the top of the second distillation column T320 serves as the heat source for the bottom of the first distillation column T310, providing the remaining required heat for the first distillation column T310.

[0021] 7) Refined methanol products were collected from the tops of the four distillation columns: the first distillation column T310, the second distillation column T320, the third distillation column T330, and the fourth distillation column T340.

[0022] The device provided by this utility model comprises the following steps:

[0023] The crude methanol feedstock 1 is divided into two streams. One stream, feedstock 2, is preheated by the feed wastewater preheater E3404, and feedstock 4 is preheated by the feed methanol preheater E3403. The two streams are then mixed to form the preheated feedstock 6, which enters the light component removal tower T300.

[0024] The light component removal tower T300 and the first distillation tower T310 are thermally integrated. The gas phase 7 at the top of the light component removal tower T300 enters the feed preheater E3101 of the first distillation tower for condensation. The condensate 9 is directly returned to the top of the light component removal tower T300, and the non-condensable gas 8 is discharged. The material 10 at the bottom of the light component removal tower T300, after being preheated by the feed preheater E3101 of the first distillation tower, enters the first distillation tower T310.

[0025] The vapor phase 11 at the top of the first distillation column T310 is condensed by the first distillation column condenser E3103, and the condensate 12 is divided into two streams. One stream is returned directly to the top of the first distillation column T310 as the reflux liquid 13, and the other stream of condensate 14 is collected as the refined methanol product. The bottom material 15 of the first distillation column T310 enters the second distillation column T320.

[0026] The second distillation column T320 and the first distillation column T310 are thermally integrated. The vapor phase 16 at the top of the second distillation column T320 enters the shell side of the reboiler E3102 of the first distillation column. The condensed liquid 17 is divided into two streams. One stream is returned directly to the top of the second distillation column T320 as the reflux liquid 18, and the other stream of condensate 19 is collected as the refined methanol product. The bottom material 20 of the second distillation column T320 enters the third distillation column T330.

[0027] The third distillation column T330 is thermally integrated with the light component removal column T300 and the second distillation column T320. The vapor phase 21 at the top of the third distillation column T330 is divided into two streams. The first stream 21-1 enters the shell side of the reboiler E-3001 of the light component removal column, and the condensate after condensation is 22-1. The other stream 21-2 enters the shell side of the reboiler E3201 of the second distillation column, and the condensate after condensation is 22-2. The condensate 22 after the two streams are mixed is then divided into two streams. One stream is used as the reflux liquid 23 of the third distillation column and is directly returned to the top of the third distillation column T330. The other condensate 24 is collected as refined methanol product. The bottom material 25 of the third distillation column T330 enters the methanol stripping side L340 of the fourth distillation column T340.

[0028] The fourth distillation column T340 and the third distillation column T330 are thermally integrated. The vapor phase 26 from the top of the fourth distillation column T340 enters the shell side of the reboiler E3301 of the third distillation column. The condensed liquid 27 is divided into two streams. One stream is returned directly to the top of the fourth distillation column T340 as the reflux liquid 28, and the other stream 29 is collected as refined methanol product. The side stream near the feed inlet of L340 on the methanol stripping side of the fourth distillation column T340 is collected as fusel oil 33 with very low methanol and ethanol content. The bottom material 35 of L340 on the methanol stripping side of the fourth distillation column T340 is collected as wastewater. The bottom material 40 of R340 on the ethanol stripping side of the fourth distillation column T340 is collected as recovered ethanol product.

[0029] The refined methanol product 30, obtained by mixing the top products 14 of the first distillation column T310, 19 of the second distillation column T320, 24 of the third distillation column T330, and 29 of the fourth distillation column T340, is cooled by the feed methanol preheater E3403. The cooled material 31 is then cooled by the methanol product cooler E3405 to obtain refined methanol product 32, which is then sent out of the unit.

[0030] Wastewater 35 collected from the bottom of L340 on the methanol stripping side of the fourth distillation column T340 is first cooled by the feed wastewater preheater E3404. The cooled material 36 is then cooled by the wastewater cooler E3406, and the resulting wastewater 37 is divided into two streams. One stream is sent out of the device as wastewater 38, and the other stream is returned to the top of the light component removal column T300 as extract water 39.

[0031] The fusel oil 33 extracted from the methanol stripping side L340 of the fourth distillation column T340 is cooled by the fusel oil cooler E3407 to obtain fusel oil product 34, which is then sent out of the unit.

[0032] The recovered ethanol 40 collected from the bottom of the fourth distillation column T340 ethanol distillation side R340 is cooled by the ethanol cooler E3408 to obtain recovered ethanol product 41, which is then sent out of the unit.

[0033] According to the multi-effect energy-saving methanol distillation apparatus provided by this utility model, if the requirement for reducing energy consumption is high, the five columns can adopt a five-effect heat integration. The top vapor phase of the fourth distillation column T340 serves as the heat source for heating the bottom of the third distillation column T330, providing the required heat for the third distillation column T330; the top vapor phase of the third distillation column T330 serves as the heat source for heating the bottom of the light component removal column T300, providing the required heat for the light component removal column T300; the top vapor phase of the light component removal column T300 serves as the heat source for heating the bottom of the second distillation column T320, providing the required heat for the second distillation column T320; and the top vapor phase of the second distillation column T320 serves as the heat source for heating the bottom of the first distillation column T310, providing the required heat for the first distillation column T310.

[0034] According to the above-mentioned multi-effect energy-saving methanol distillation apparatus, the following five-tower, five-effect modified process can be adopted in the five-tower configuration:

[0035] 1) The light component removal column T300 is moved between the fourth distillation column T340 and the third distillation column T330: the vapor phase from the top of the fourth distillation column T340 serves as the heat source for heating the bottom of the light component removal column T300, providing the required heat for the light component removal column T300; the vapor phase from the top of the light component removal column T300 serves as the heat source for heating the bottom of the third distillation column T330, providing the required heat for the third distillation column T330; the vapor phase from the top of the third distillation column T330 serves as the heat source for heating the bottom of the second distillation column T320, providing the required heat for the second distillation column T320; the vapor phase from the top of the second distillation column T320 serves as the heat source for heating the bottom of the first distillation column T310, providing the remaining required heat for the first distillation column T310.

[0036] 2) The light component removal column T300 is moved between the second distillation column T320 and the first distillation column T310: the vapor phase from the top of the fourth distillation column T340 serves as the heat source for heating the bottom of the third distillation column T330, providing the required heat for the third distillation column T330; the vapor phase from the top of the third distillation column T330 serves as the heat source for heating the bottom of the second distillation column T320, providing the required heat for the second distillation column T320; the vapor phase from the top of the second distillation column T320 serves as the heat source for heating the bottom of the light component removal column T300, providing the required heat for the light component removal column T300; the vapor phase from the top of the light component removal column T300 serves as the heat source for heating the bottom of the first distillation column T310, providing the required heat for the first distillation column T310.

[0037] 3) After the light component removal column T300 is moved to the first distillation column T310: the vapor phase from the top of the fourth distillation column T340 serves as the heat source for heating the bottom of the third distillation column T330, providing the required heat for the third distillation column T330; the vapor phase from the top of the third distillation column T330 serves as the heat source for heating the bottom of the second distillation column T320, providing the required heat for the second distillation column T320; the vapor phase from the top of the second distillation column T320 serves as the heat source for heating the bottom of the first distillation column T310, providing the required heat for the first distillation column T310; the vapor phase from the top of the first distillation column T310 serves as the heat source for heating the bottom of the light component removal column T300, providing the required heat for the light component removal column T300.

[0038] According to the above-mentioned multi-effect energy-saving methanol distillation apparatus, in the five towers, generally when the light component removal tower T300 does not require as much heat in the process as the above-mentioned multi-effect energy-saving methanol distillation apparatus, the following modified process of five-effect plus four-effect can be adopted to reduce the supply of heat integrated energy of the light component removal tower T300, thereby reducing the equipment specifications of the light component removal tower T300 and reducing investment.

[0039] 1) The vapor phase from the top of the fourth distillation column T340 is divided into two streams. One stream serves as the heat source for heating the reboiler of the third distillation column T330, providing a portion of the required heat for T330. The other stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300. The vapor phase from the top of the light component removal column T300 also serves as the heat source for heating the reboiler of the third distillation column T330, providing the remaining required heat for T330. T340, T300, T330, T320, and T310 constitute a five-effect thermal integration, and T340, T330, T320, and T310 constitute a four-effect thermal integration. The entire unit constitutes a five-column, five-effect plus four-effect distillation process.

[0040] 2) The vapor phase at the top of the third distillation column T330 is divided into two streams. One stream serves as the heat source for heating the reboiler of the second distillation column T320, providing a portion of the required heat for T320. The other stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300. The vapor phase at the top of the light component removal column T300 also serves as the heat source for heating the reboiler of the second distillation column T320, providing the remaining required heat for T320. T340, T330, T300, T320, and T310 constitute a five-effect thermal integration, and T340, T330, T320, and T310 constitute a four-effect thermal integration. The entire unit constitutes a five-column, five-effect plus four-effect distillation process.

[0041] 3) The vapor phase at the top of the second distillation column T320 is divided into two streams. One stream serves as the heat source for heating the reboiler of the first distillation column T310, providing a portion of the required heat for T310. The other stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300. The vapor phase at the top of the light component removal column T300 also serves as the heat source for heating the reboiler of the first distillation column T310, providing the remaining required heat for T310. T340, T330, T320, T300, and T310 constitute a five-effect thermal integration, and T340, T330, T320, and T310 constitute a four-effect thermal integration. The entire unit constitutes a five-column, five-effect plus four-effect distillation process.

[0042] According to the process method provided by the device of this utility model, when the energy consumption requirement of the device is not high, the following modified process of five towers with double four effects can be adopted to reduce the operating pressure of some equipment, thereby reducing the pressure level of some equipment and reducing investment.

[0043] 1) The vapor phase from the top of the fourth distillation column T340 is divided into two streams. One stream serves as the heat source for heating the reboiler of the third distillation column T330, providing the required heat for T330. The other stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300. The vapor phases from the top of the third distillation column T330 and the light component removal column T300 serve as the heat sources for heating the reboiler of the second distillation column T320, providing the required heat for T320. T340, T300, T320, and T310 constitute a four-effect thermal integration system, and the entire unit constitutes a five-column double four-effect distillation process.

[0044] 2) The reboils of the fourth distillation column T340 and the light component removal column T300 are both heated by external heat sources. The overhead vapor phases of the fourth distillation column T340 and the light component removal column T300 are used as heat sources to heat the reboiler of the third distillation column T330, providing the required heat for the third distillation column T330. T300, T330, T320, and T310 constitute a four-effect heat integration, and T340, T330, T320, and T310 also constitute a four-effect heat integration. The entire unit constitutes a five-column double four-effect distillation process.

[0045] 3) The vapor phase at the top of the second distillation column T320 is divided into two streams. One stream serves as the heat source for heating the bottom of the first distillation column T310, providing the necessary heat for T310. The other stream serves as the heat source for heating the bottom of the light component removal column T300, providing the necessary heat for T300. T340, T330, T320, and T300 constitute a four-effect thermal integration, and the entire unit constitutes a five-column double four-effect distillation process.

[0046] According to the multi-effect energy-saving methanol distillation apparatus provided by this utility model, the lower part of the fourth distillation column T340 adopts a partition column structure, and the partition S340 divides the lower part of the fourth distillation column T340 into a methanol stripping side L340 and an ethanol distillation side R340; wastewater 35 is discharged from the bottom of the methanol stripping side L340 of the fourth distillation column T340; fusel oil 33 with very low methanol and ethanol content is collected from the side stream below the feed inlet of the methanol stripping side L340 of the fourth distillation column T340; and recovered ethanol product 40 is collected from the bottom of the ethanol distillation side R340 of the fourth distillation column T340.

[0047] The multi-effect energy-saving methanol distillation apparatus provided by this utility model can also be modified into other integrated thermal processes for methanol production:

[0048] 1) The fourth distillation column T340 does not use a partition structure, but adopts a conventional partitionless structure. The recovered ethanol 40 is collected above the feed inlet of the fourth distillation column T340, and fusel oil 33 is collected below the feed inlet. The bottom material of the fourth distillation column T340 is collected as wastewater 35.

[0049] 2) Add a stripping tower T340S. The fourth distillation tower T340 does not use a partition structure, but adopts a conventional partitionless structure. The side stream liquid material 42 of the fourth distillation tower T340 enters the top of the stripping tower T340S. The top gaseous material 43 of the stripping tower T340S returns to the fourth distillation tower T340. The bottom of the stripping tower T340S is used to recover ethanol 40.

[0050] 3) Add a recovery tower T350. The fourth distillation tower T340 does not use a partition structure, but adopts a conventional partitionless structure. The recovery tower T350 can use the top gas phase of the first distillation tower T310, the second distillation tower T320, or the fourth distillation tower T340 as a heat source, or use an external heat source.

[0051] According to the multi-effect energy-saving methanol distillation apparatus provided by this utility model, when the energy consumption requirements of the apparatus are very high, the following process of optimizing and modifying the periphery of the light component removal tower T300 to form a five-tower five-effect or six-tower double five-effect can be adopted to reduce operating energy consumption.

[0052] 1) Add a light component removal distillation column T300D to the light component removal column T300. It shares the reboiler and reboiler E3001 with the light component removal column T300. The overhead vapor phases of both the light component removal column T300 and the light component removal distillation column T300D are used as the heat source for heating the reboiler of the third distillation column T330, providing the required heat for the third distillation column T330. The top of the light component removal distillation column T300D produces refined methanol.

[0053] 2) A fifth distillation column T360 is connected in parallel with the light component removal column T300. The overhead vapor from the fourth distillation column T340 is split into two streams: one stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300; the other stream serves as the heat source for heating the reboiler of the fifth distillation column T360, providing the required heat for T360. The overhead vapor from both the light component removal column T300 and the fifth distillation column T360 serves as the heat source for heating the reboiler of the third distillation column T330, providing the required heat for T330. Refined methanol is collected from the top of the fifth distillation column T360.

[0054] 3) The upper part of the light component removal tower T300 adopts a partition tower structure. Partition two (S300) divides the upper part of the light component removal tower T300 into a pre-distillation side R300 and a methanol distillation side L300. The vapor phases at the top of the pre-distillation side R300 and the methanol distillation side L300 are used as the heat source for heating the bottom of the third distillation tower T330, providing the required heat for the third distillation tower T330. The methanol product is collected from the top of the methanol distillation side L300. The lower part and bottom of the light component removal tower T300 are conventional partitionless structures.

[0055] The energy-saving method selected from the multi-effect energy-saving methanol distillation apparatus provided by this utility model is as follows:

[0056] 1) The crude methanol feedstock can exchange heat with the wastewater discharged from the bottom of the L340 column on the methanol stripping side of the fourth distillation column T340, the crude methanol feedstock can also exchange heat with the refined methanol product, and the crude methanol feedstock can also exchange heat with the gas phase at the top of the first distillation column T310.

[0057] 2) Heat exchange between the feed and heating steam condensate of each distillation column, such as the first distillation column T310, the second distillation column T320, the third distillation column T330, the fourth distillation column T340, or the light component removal column T300.

[0058] Typical implementation methods for heat exchange between this steam condensate and the feed to each tower include:

[0059] 1) The steam condensate first exchanges heat with the feed of the fourth distillation column T340 to preheat the feed of the fourth distillation column T340;

[0060] 2) The steam condensate after heat exchange with the feed of the fourth distillation column T340 is then heat exchanged with the feed of the third distillation column T330 to preheat the feed of the third distillation column T330.

[0061] 3) The steam condensate after heat exchange with the feed of the third distillation column T330 is then heat exchanged with the feed of the light component removal column T300 and the second distillation column T320 respectively to preheat the feed of the light component removal column T300 and the second distillation column T320 respectively.

[0062] 4) The steam condensate after heat exchange with the feed of the light component removal tower T300 and the second distillation tower T320 is then heat exchanged with the feed of the first distillation tower T310 to preheat the feed of the first distillation tower T310.

[0063] The condensate vapor can be used to preheat the feed to the light component removal tower, or to the first distillation tower, or to the second distillation tower, or to the third distillation tower, or to the fourth distillation tower. The condensate vapor can also be used to preheat any tower or combination thereof within the system. The above heat exchange methods are only a supplement to the energy-saving multi-effect methanol distillation device for methanol distillation provided by this utility model, and are not any limitation on the spirit of this utility model. Those skilled in the art can arrange and combine the above heat exchange processes according to common sense, and all the resulting evolutionary process flows should be considered within the spirit, scope and content of this utility model.

[0064] According to the multi-effect energy-saving methanol distillation apparatus provided by this utility model, the top product 14 of the first distillation column T310, the top product 19 of the second distillation column T320, the top product 24 of the third distillation column T330, and the top product 29 of the fourth distillation column T340 can also be extracted from the upper side stream of each column.

[0065] According to the multi-effect energy-saving methanol distillation apparatus provided by this utility model, the heat source used for the methanol stripping side reboiler E3401 and the ethanol distillation side reboiler E3402 of the fourth distillation column can be fresh steam, heat transfer oil, or material steam generated inside the system.

[0066] According to the multi-effect energy-saving methanol distillation apparatus provided by this utility model, the light component removal column T300, the first distillation column T310, the second distillation column T320, the third distillation column T330, and the fourth distillation column T340, while employing integrated heating, can also utilize external heating sources to provide heat to the column core or reboiler. These external heating sources can be fresh steam, hot water, heat transfer oil, or other low-grade heat sources within the system. Each column can simultaneously or separately utilize the aforementioned other low-grade heat sources to heat the column core or reboiler.

[0067] According to the multi-effect energy-saving methanol distillation apparatus provided by this utility model, the first distillation column condenser E3103, methanol product cooler E3405, wastewater cooler E3406, fusel oil cooler E3407, and ethanol cooler E3408 can be air coolers or water coolers; the cooling medium used can be circulating water, low-temperature water, chilled water, or other cooling media such as low-temperature materials inside the system.

[0068] According to the multi-effect energy-saving methanol distillation apparatus provided by this utility model, the bottom discharge of the light component removal tower T300 first enters the first distillation tower T310, or first enters the second distillation tower T320, or first enters the third distillation tower T330; or enters the first distillation tower T310 and the second distillation tower T320 respectively; or enters the first distillation tower T310 and the third distillation tower T330 respectively; or enters the second distillation tower T320 and the third distillation tower T330 respectively; or enters the first distillation tower T310, the second distillation tower T320 and the third distillation tower T330 respectively.

[0069] The multi-effect methanol distillation device (five-tower double four-effect thermal integration, or five-tower five-effect thermal integration, or six-tower five-effect thermal integration, or five-tower five-effect plus four-effect thermal integration, or six-tower five-effect plus four-effect thermal integration, or six-tower double four-effect thermal integration) provided by this utility model is an energy-saving device for methanol distillation and can be used to produce national standard superior grade methanol, US standard AA grade methanol products, or other specifications of methanol products.

[0070] The typical operating conditions for each column in the multi-effect energy-saving methanol distillation system provided by this utility model are as follows:

[0071] The operating pressure range at the top of the T300 light component removal tower is 60–300 kPa.

[0072] The operating pressure range of the top of the first distillation column T310 is 25–150 kPa;

[0073] The operating pressure range of the top of the second distillation column T320 is 60–300 kPa;

[0074] The operating pressure range of the top of the third distillation column T330 is 100–600 kPa;

[0075] The operating pressure range of the top of the fourth distillation column T340 is 250–1300 kPa.

[0076] The preferred operating conditions for each tower are as follows:

[0077] The operating pressure at the top of the T300 light component removal tower is 82–160 kPa, the operating temperature at the top is 59–76 °C, and the operating temperature at the bottom is 65–85 °C.

[0078] The first distillation column T310 has an operating pressure of 44–69 kPa at the top, an operating temperature of 45–55 °C at the top, and an operating temperature of 50–65 °C at the bottom.

[0079] The operating pressure at the top of the second distillation column T320 is 82–160 kPa, the operating temperature at the top is 59–76 °C, and the operating temperature at the bottom is 68–85 °C.

[0080] The operating pressure at the top of the third distillation column T330 is 176–391 kPa, the operating temperature at the top is 79–103 °C, and the operating temperature at the bottom is 90–116 °C.

[0081] The operating pressure at the top of the fourth distillation column T340 is 356–869 kPa, and the operating temperature at the top is 100–131 °C. The operating temperature at the bottom of the methanol stripping column L340 is 142–173 °C, and the operating temperature at the bottom of the ethanol distillation column R340 is 110–150 °C.

[0082] The multi-effect energy-saving methanol distillation apparatus provided by this utility model mainly includes five distillation towers: a light component removal tower T300, a first distillation tower T310, a second distillation tower T320, a third distillation tower T330, and a fourth distillation tower T340, as well as connecting pipelines.

[0083] The raw material crude methanol feed pipeline is connected to the cold side inlet of the feed methanol preheater E3403 and the feed wastewater preheater E3404, respectively.

[0084] The cold-side outlets of the methanol feed preheater E3403 and the wastewater feed preheater E3404 are connected to the middle of the light component removal tower T300; the top of the light component removal tower T300 is connected to the hot-side inlet of the first distillation tower feed preheater E3101, the hot-side condensate outlet of the first distillation tower feed preheater E3101 is connected to the top of the light component removal tower T300, and the hot-side non-condensable gas outlet of the first distillation tower feed preheater E3101 is connected to the non-condensable gas discharge pipeline; the bottom of the light component removal tower T300 is connected to the tube-side inlet of the light component removal tower reboiler E3001 and the cold-side inlet of the first distillation tower feed preheater E3101, respectively; the tube-side outlet of the light component removal tower reboiler E3001 is connected to the bottom of the light component removal tower T300; and the cold-side outlet of the first distillation tower feed preheater E3101 is connected to the feed inlet in the middle of the first distillation tower T310.

[0085] The top of the first distillation column T310 is connected to the first distillation column condenser E3103. The condensate outlet of the first distillation column condenser E3103 is connected to the top of the first distillation column T310 and the hot-side inlet of the feed methanol preheater E3403, respectively. The middle feed inlet of the first distillation column T310 is connected to the cold-side outlet of the feed preheater E3101. The bottom of the first distillation column T310 is connected to the tube-side inlet of the first distillation column reboiler E3102 and the second distillation column T320. The tube-side outlet of the first distillation column reboiler E3102 is connected to the bottom of the first distillation column T310.

[0086] The top of the second distillation column T320 is connected to the shell side of the reboiler E3102 of the first distillation column. The condensate outlet of the shell side of the reboiler E3102 of the first distillation column is connected to the top of the second distillation column T320 and the hot side inlet of the feed methanol preheater E3403, respectively. The bottom of the second distillation column T320 is connected to the tube side inlet of the reboiler E3201 of the second distillation column and the third distillation column T330, respectively. The tube side outlet of the reboiler E3201 of the second distillation column is connected to the bottom of the second distillation column T320.

[0087] The top of the third distillation column T330 is connected to the shell side of the reboiler E3001 of the light component removal column and the shell side of the reboiler E3201 of the second distillation column. The condensate outlet of the shell side of the reboiler E3001 of the light component removal column and the condensate outlet of the shell side of the reboiler E3201 of the second distillation column are connected to the top of the third distillation column T330 and the hot-side inlet of the methanol feed preheater E3403, respectively. The bottom of the third distillation column T330 is connected to the tube side inlet of the reboiler E3301 of the third distillation column and the fourth distillation column T340.

[0088] The top of the fourth distillation column T340 is connected to the shell side of the reboiler E3301 of the third distillation column. The condensate outlet of the shell side of the reboiler E3301 is connected to the top of the fourth distillation column T340 and the hot-side inlet of the feed methanol preheater E3403, respectively. The bottom of the methanol stripping side L340 of the fourth distillation column T340 is connected to the tube side inlet of the methanol stripping side reboiler E3401 and the hot-side inlet of the feed wastewater preheater E3404, respectively. The tube side outlet of the methanol stripping side reboiler E3401 is connected to the fourth distillation column T340. The methanol stripping side L340 of the fourth distillation column T340 has a bottom; the side feed line near the feed of the methanol stripping side L340 of the fourth distillation column T340 is connected to the hot side inlet of the fusel oil cooler E3407; the bottom of the ethanol distillation side R340 of the fourth distillation column T340 is connected to the tube side inlet of the ethanol distillation side reboiler E3402 and the hot side inlet of the ethanol cooler E3408, respectively; the tube side outlet of the ethanol distillation side reboiler E3402 of the fourth distillation column T340 is connected to the bottom of the ethanol distillation side R340 of the fourth distillation column T340.

[0089] The hot-side outlet of the methanol preheater E3403 is connected to the hot-side inlet of the methanol product cooler E3405, and the hot-side outlet of the methanol product cooler E3405 is connected to the methanol product outlet pipeline.

[0090] The hot-side outlet of the feed wastewater preheater E3404 is connected to the hot-side inlet of the wastewater cooler E3406. The hot-side outlet of the wastewater cooler E3406 is connected to the top of the light component removal tower T300 and the wastewater discharge pipeline, respectively. The hot-side outlet of the fusel oil cooler E3407 is connected to the fusel oil product collection pipeline. The hot-side outlet of the ethanol cooler E3408 is connected to the ethanol product collection pipeline.

[0091] If the wastewater 38 contains many impurities, which is not conducive to the extraction and phase separation of the light component removal tower, the extraction water of the light component removal tower can also be other process water such as demineralized water; the extraction water of the light component removal tower can be added to the top of the tower, or to the reflux tank of the light component removal tower, or to the condensate tank of the tail cooler of the light component removal tower; these are all conventional process methods in this professional field and do not constitute any limitation on this utility model.

[0092] To highlight the multi-effect energy-saving methanol distillation apparatus provided by this utility model, some heat exchangers in the process flow are omitted. Those skilled in the art can implement suitable internal heat exchange methods for the system's fluids based on the specific apparatus conditions provided by this utility model, and all resulting evolutionary process flows should be considered within the spirit, scope, and content of this utility model. The heat exchangers in the simplified flow diagram are merely illustrative, and their specific structural forms do not constitute any limitation on this utility model.

[0093] The multi-effect energy-saving methanol distillation apparatus provided by this invention can significantly reduce operating energy consumption. It can be used in the distillation process of various methanol solvent recovery and methanol synthesis units to produce national standard superior grade methanol, US standard AA grade methanol, or other specifications of methanol products. It overcomes the shortcomings of existing technologies, reducing the steam consumption per unit of refined methanol to below 0.48, demonstrating significant practicality and economic benefits, and showing broad application prospects. Attached Figure Description

[0094] Figure 1 This is a flowchart of the four-tower (three towers plus one tower) methanol distillation process used in existing technologies.

[0095] Figure 2 This utility model provides a typical multi-effect energy-saving methanol distillation device (five-tower double four-effect thermal integrated device) process flow diagram for methanol distillation.

[0096] Figure 3 yes Figure 2 One type of evolutionary process, namely, modified process method one, is relatively... Figure 2 The provided process involves a five-effect thermal integration among the five distillation columns. The top vapor phase of the fourth distillation column T340 serves as the heat source for the bottom of the third distillation column T330, providing the required heat for T330. The top vapor phase of the third distillation column T330 serves as the heat source for the bottom of the light component removal column T300, providing the required heat for T300. The top vapor phase of the light component removal column T300 serves as the heat source for the bottom of the second distillation column T320, providing the required heat for T320. The top vapor phase of the second distillation column T320 serves as the heat source for the bottom of the first distillation column T310, providing the required heat for T310.

[0097] Figure 4 yes Figure 3 One type of evolutionary process, namely, modified process method two, is relatively... Figure 3 The provided process involves moving the light component removal column T300 between the fourth distillation column T340 and the third distillation column T330: the overhead vapor phase of the fourth distillation column T340 serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300; the overhead vapor phase of the light component removal column T300 serves as the heat source for heating the reboiler of the third distillation column T330, providing the required heat for T330; the overhead vapor phase of the third distillation column T330 serves as the heat source for heating the reboiler of the second distillation column T320, providing the required heat for T320; and the overhead vapor phase of the second distillation column T320 serves as the heat source for heating the reboiler of the first distillation column T310, providing the remaining required heat for T310.

[0098] Figure 5 yes Figure 3 One of the evolutionary process methods, namely the modified process method three, is relatively... Figure 3 The provided process involves moving the light component removal column T300 between the second distillation column T320 and the first distillation column T310: the overhead vapor phase of the fourth distillation column T340 serves as the heat source for heating the reboiler of the third distillation column T330, providing the required heat for the third distillation column T330; the overhead vapor phase of the third distillation column T330 serves as the heat source for heating the reboiler of the second distillation column T320, providing the required heat for the second distillation column T320; the overhead vapor phase of the second distillation column T320 serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for the light component removal column T300; and the overhead vapor phase of the light component removal column T300 serves as the heat source for heating the reboiler of the first distillation column T310, providing the required heat for the first distillation column T310.

[0099] Figure 6 yes Figure 3 One type of evolutionary process, namely, modified process method four, is relatively... Figure 3 The provided process involves the following steps after the light component removal column T300 is moved to the first distillation column T310: the vapor phase from the top of the fourth distillation column T340 serves as the heat source for the reboiler of the third distillation column T330, providing the required heat for T330; the vapor phase from the top of the third distillation column T330 serves as the heat source for the reboiler of the second distillation column T320, providing the required heat for T320; the vapor phase from the top of the second distillation column T320 serves as the heat source for the reboiler of the first distillation column T310, providing the required heat for T310; and the vapor phase from the top of the first distillation column T310 serves as the heat source for the reboiler of the light component removal column T300, providing the required heat for T300.

[0100] Figure 7 yes Figure 4 One of the evolutionary process methods, namely, the fifth modified process method, is relatively... Figure 4The provided process involves the following: the vapor phase from the top of the fourth distillation column T340 is divided into two streams. One stream serves as the heat source for heating the reboiler of the third distillation column T330, providing a portion of the required heat for T330. The other stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300. The vapor phase from the top of the light component removal column T300 also serves as the heat source for heating the reboiler of the third distillation column T330, providing the remaining required heat for T330.

[0101] Figure 8 yes Figure 3 One type of evolutionary process, namely, modified process method six, is relatively... Figure 3 The provided process involves the top vapor phase of the third distillation column T330 being divided into two streams. One stream serves as the heat source for heating the reboiler of the second distillation column T320, providing a portion of the required heat for T320. The other stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300. The top vapor phase of the light component removal column T300 also serves as the heat source for heating the reboiler of the second distillation column T320, providing the remaining required heat for T320.

[0102] Figure 9 yes Figure 5 One of the evolutionary process methods, namely the modified process method seven, is relatively... Figure 5 The provided process involves the following: the vapor phase at the top of the second distillation column T320 is divided into two streams. One stream serves as the heat source for heating the bottom of the first distillation column T310, providing a portion of the required heat for T310. The other stream serves as the heat source for heating the bottom of the light component removal column T300, providing the required heat for T300. The vapor phase at the top of the light component removal column T300 also serves as the heat source for heating the bottom of the first distillation column T310, providing the remaining required heat for T310.

[0103] Figure 10 yes Figure 2 One type of evolutionary process, namely, variation process method eight, relative to Figure 2 The provided process involves the following: the overhead vapor from the fourth distillation column T340 is divided into two streams. One stream serves as the heat source for heating the reboiler of the third distillation column T330, providing the required heat for T330. The other stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300. The overhead vapors from the third distillation column T330 and the light component removal column T300 serve as the heat sources for heating the reboiler of the second distillation column T320, respectively, providing the required heat for T320.

[0104] Figure 11 yes Figure 2 One of the evolutionary process methods, namely, the modified process method nine, is relatively... Figure 2The provided process involves external heat sources heating the reboils of the fourth distillation column T340 and the light component removal column T300; the overhead vapor phases of the fourth distillation column T340 and the light component removal column T300 are used as heat sources to heat the reboiler of the third distillation column T330, providing the required heat for the third distillation column T330.

[0105] Figure 12 yes Figure 2 One type of evolutionary process, namely, the modified process method ten, relative to Figure 2 The provided process involves the top gas phase of the second distillation column T320 being divided into two streams. One stream serves as the heat source for heating the bottom of the first distillation column T310, providing the required heat for the first distillation column T310. The other stream serves as the heat source for heating the bottom of the light component removal column T300, providing the required heat for the light component removal column T300.

[0106] Figure 13 yes Figure 2 One type of evolutionary process, namely, variation process method eleven, is relatively... Figure 2 The provided process indicates that the fourth distillation column T340 does not use a partition structure, but adopts a conventional partitionless structure. The recovered ethanol 40 is collected above the feed inlet of the fourth distillation column T340, and fusel oil 33 is collected below the feed inlet. The bottom material of the fourth distillation column T340 is collected as wastewater 35.

[0107] Figure 14 yes Figure 2 One of the evolutionary process methods, namely the modified process method twelve, is relatively... Figure 2 The provided process involves adding a stripping tower T340S. The fourth distillation tower T340 does not use a partition structure, but adopts a conventional partitionless structure. The side stream liquid material 42 of the fourth distillation tower T340 enters the top of the stripping tower T340S, and the top gaseous material 43 of the stripping tower T340S returns to the fourth distillation tower T340. The bottom of the stripping tower T340S is used to recover ethanol 40.

[0108] Figure 15 yes Figure 2 One of the evolutionary process methods, namely the modified process method thirteen, is relatively... Figure 2 The provided process adds a recovery tower T350, and the fourth distillation tower T340 does not use a partition structure, but adopts a conventional partitionless structure; the recovery tower T350 can use the top gas phase of the first distillation tower T310, the second distillation tower T320, or the fourth distillation tower T340 as a heat source, or use an external heat source.

[0109] Figure 16 yes Figure 4 One type of evolutionary process, namely, the fourteenth variation process, is relatively... Figure 4The provided process involves adding a light component removal distillation column T300D to the light component removal column T300. T300D shares the reboiler and reboiler E3001 with the light component removal column T300. The overhead vapor phases of both the light component removal column T300 and the light component removal distillation column T300D serve as the heat source for heating the reboiler of the third distillation column T330, providing the required heat for the third distillation column T330. Refined methanol is collected from the top of the light component removal column T300D.

[0110] Figure 17 yes Figure 4 One type of evolutionary process, namely, variation process method fifteen, relative to Figure 4 The provided process involves a light component removal column T300 connected in parallel with a fifth distillation column T360. The overhead vapor from the fourth distillation column T340 is split into two streams: one stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the necessary heat; the other stream serves as the heat source for heating the reboiler of the fifth distillation column T360, providing the necessary heat. The overhead vapor from both the light component removal column T300 and the fifth distillation column T360 serves as the heat source for heating the reboiler of the third distillation column T330, providing the necessary heat. Refined methanol is collected from the top of the fifth distillation column T360.

[0111] Figure 18 yes Figure 4 One type of evolutionary process, namely, the sixteenth variation process, is relatively... Figure 4 The provided process involves a partitioned column structure at the top of the light component removal column T300. Partition two (S300) divides the upper part of the light component removal column T300 into a pre-distillation side R300 and a methanol distillation side L300. The vapor phases at the top of both the pre-distillation side R300 and the methanol distillation side L300 serve as the heat source for heating the bottom of the third distillation column T330, providing the required heat for the third distillation column T330. Refined methanol is collected from the top of the methanol distillation side L300. The lower part and bottom of the light component removal column T300 are conventional partitionless structures.

[0112] Figure 19 yes Figure 2 One type of evolutionary process, namely, the seventeenth variation process, is relatively... Figure 2 The provided process allows the light component removal column T300, the first distillation column T310, the second distillation column T320, and the third distillation column T330 to use integrated heating, while also employing external heating sources to provide heat to the column reboilers. These external heating sources can be fresh steam, heat transfer oil, or other low-grade heat sources within the system.

[0113] According to the apparatus of the process method provided by this utility model and the apparatus of the above-mentioned modified process method, those skilled in the relevant professional fields can fully implement appropriate internal material heat exchange methods according to specific apparatus conditions. The apparatus of various evolved process flows formed therefrom should be regarded as being within the spirit, scope and content of this utility model. Detailed Implementation

[0114] The specific implementation scheme of this utility model is described in detail below with reference to the accompanying drawings, but is for illustrative purposes only and not as a limitation thereof. Unless otherwise specified, the composition and structure of the process equipment such as tower components, materials (connecting pipelines, etc., used to connect the various tower components), reagents, etc., not specifically indicated in the embodiments, can all be obtained commercially or by methods known to those skilled in the art. The specific experimental methods and operating conditions involved are generally in accordance with conventional process conditions and the conditions described in the manual, or the conditions recommended by the manufacturer.

[0115] Application Example 1:

[0116] The typical composition of crude methanol feedstock is as follows:

[0117] Component mass percentage (%)

[0118] Carbon monoxide 0.035

[0119] Carbon dioxide 1.065

[0120] Water 4.575

[0121] Methanol 94,000

[0122] 0.048g of dimethyl ether

[0123] Methyl formate 0.040

[0124] 0.004g of acetone

[0125] 0.150g of ethanol

[0126] n-Propanol 0.048

[0127] n-Butanol 0.010

[0128] Isobutanol 0.010

[0129] n-Pentanol 0.012

[0130] 0.003 Methyl ethyl ketone

[0131] Total: 100.00.

[0132] The above-mentioned range of raw material composition does not constitute any limitation on this utility model. This utility model can be used in the distillation process of crude methanol raw materials with various compositions.

[0133] like Figure 2 As shown, crude methanol feedstock 1 is divided into two streams. One stream, feedstock 2, is preheated by feed wastewater preheater E3404, and feedstock 4 is preheated by feed methanol preheater E3403. The two streams are then mixed to form preheated feedstock 6, which enters the light component removal tower T300.

[0134] The light component removal tower T300 and the first distillation tower T310 are thermally integrated. The gas phase 7 at the top of the light component removal tower T300 enters the feed preheater E3101 of the first distillation tower for condensation. The condensate 9 is directly returned to the top of the light component removal tower T300, and the non-condensable gas 8 is discharged. The material 10 at the bottom of the light component removal tower T300, after being preheated by the feed preheater E3101 of the first distillation tower, enters the first distillation tower T310.

[0135] The vapor phase 11 at the top of the first distillation column T310 is condensed by the first distillation column condenser E3103, and the condensate 12 is divided into two streams. One stream is returned directly to the top of the first distillation column T310 as the reflux liquid 13, and the other stream of condensate 14 is collected as the refined methanol product. The bottom material 15 of the first distillation column T310 enters the second distillation column T320.

[0136] The second distillation column T320 and the first distillation column T310 are thermally integrated. The vapor phase 16 at the top of the second distillation column T320 enters the shell side of the reboiler E3102 of the first distillation column. The condensed liquid 17 is divided into two streams. One stream is returned directly to the top of the second distillation column T320 as the reflux liquid 18, and the other stream of condensate 19 is collected as the refined methanol product. The bottom material 20 of the second distillation column T320 enters the third distillation column T330.

[0137] The third distillation column T330 is thermally integrated with the light component removal column T300 and the second distillation column T320. The vapor phase 21 at the top of the third distillation column T330 is divided into two streams. The first stream 21-1 enters the shell side of the reboiler E-3001 of the light component removal column, and the condensate after condensation is 22-1. The other stream 21-2 enters the shell side of the reboiler E3201 of the second distillation column, and the condensate after condensation is 22-2. The condensate 22 after the two streams are mixed is then divided into two streams. One stream is used as the reflux liquid 23 of the third distillation column and is directly returned to the top of the third distillation column T330. The other condensate 24 is collected as refined methanol product. The bottom material 25 of the third distillation column T330 enters the methanol stripping side L340 of the fourth distillation column T340.

[0138] The fourth distillation column T340 and the third distillation column T330 are thermally integrated. The vapor phase 26 from the top of the fourth distillation column T340 enters the shell side of the reboiler E3301 of the third distillation column. The condensed liquid 27 is divided into two streams. One stream is returned directly to the top of the fourth distillation column T340 as the reflux liquid 28, and the other stream 29 is collected as refined methanol product. The side stream near the feed inlet of L340 on the methanol stripping side of the fourth distillation column T340 is collected as fusel oil 33 with very low methanol and ethanol content. The bottom material 35 of L340 on the methanol stripping side of the fourth distillation column T340 is collected as wastewater. The bottom material 40 of R340 on the ethanol stripping side of the fourth distillation column T340 is collected as recovered ethanol product.

[0139] The refined methanol product 30, obtained by mixing the top products 14 of the first distillation column T310, 19 of the second distillation column T320, 24 of the third distillation column T330, and 29 of the fourth distillation column T340, is cooled by the feed methanol preheater E3403. The cooled material 31 is then cooled by the methanol product cooler E3405 to obtain refined methanol product 32, which is then sent out of the unit.

[0140] Wastewater 35 collected from the bottom of L340 on the methanol stripping side of the fourth distillation column T340 is first cooled by the feed wastewater preheater E3404. The cooled material 36 is then cooled by the wastewater cooler E3406, and the resulting wastewater 37 is divided into two streams. One stream is sent out of the device as wastewater 38, and the other stream is returned to the top of the light component removal column T300 as extract water 39.

[0141] The fusel oil 33 extracted from the methanol stripping side L340 of the fourth distillation column T340 is cooled by the fusel oil cooler E3407 to obtain fusel oil product 34, which is then sent out of the unit.

[0142] The recovered ethanol 40 collected from the bottom of the fourth distillation column T340 ethanol distillation side R340 is cooled by the ethanol cooler E3408 to obtain recovered ethanol product 41, which is then sent out of the unit.

[0143] The heat source used for the reboiler E3401 on the methanol stripping side of the fourth distillation column and the reboiler E3402 on the ethanol stripping side of the fourth distillation column can be fresh steam, heat transfer oil, or material steam generated inside the system.

[0144] The condensate from the fresh steam added to the system can be used to preheat the feed to each tower, either individually or sequentially.

[0145] The first distillation column condenser E3103, methanol product cooler E3405, wastewater cooler E3406, fusel oil cooler E3407, and ethanol cooler E3408 can be air coolers or water coolers; the cooling medium used can be circulating water, low-temperature water, chilled water, or other cooling media such as low-temperature materials inside the system.

[0146] The typical operating conditions for each tower in Example 1 are given below:

[0147] The operating pressure range at the top of the T300 light component removal tower is 60–300 kPa.

[0148] The operating pressure range of the top of the first distillation column T310 is 25–150 kPa;

[0149] The operating pressure range of the top of the second distillation column T320 is 60–300 kPa;

[0150] The operating pressure range of the top of the third distillation column T330 is 100–600 kPa;

[0151] The operating pressure range of the top of the fourth distillation column T340 is 250–1300 kPa.

[0152] The preferred operating conditions and operating energy consumption for each tower in Example 1 are given below:

[0153] The operating pressure at the top of the T300 light component removal tower is 82–160 kPa, the operating temperature at the top is 59–76 °C, and the operating temperature at the bottom is 65–85 °C.

[0154] The first distillation column T310 has an operating pressure of 44–69 kPa at the top, an operating temperature of 45–55 °C at the top, and an operating temperature of 50–65 °C at the bottom.

[0155] The operating pressure at the top of the second distillation column T320 is 82–160 kPa, the operating temperature at the top is 59–76 °C, and the operating temperature at the bottom is 68–85 °C.

[0156] The operating pressure at the top of the third distillation column T330 is 176–391 kPa, the operating temperature at the top is 79–103 °C, and the operating temperature at the bottom is 90–116 °C.

[0157] The operating pressure at the top of the fourth distillation column T340 is 356–869 kPa, and the operating temperature at the top is 100–131 °C. The operating temperature at the bottom of the methanol stripping column L340 is 142–173 °C, and the operating temperature at the bottom of the ethanol distillation column R340 is 110–150 °C.

[0158] Only the reboiler E3401 on the methanol stripping side of the fourth distillation column and the reboiler E3402 on the ethanol distillation side of the fourth distillation column require external heating sources. The heat sources required by the other reboilers and preheaters can be obtained from the internal heat sources of the system and steam condensate.

[0159] The external heating source is considered to be medium-pressure steam. The plant scale is based on an annual production of 1 million tons of US standard AA grade methanol (operating hours of 8000 hours / year). According to the currently widely used four-tower methanol distillation process, the steam consumption of methanol distillation is about 1.2 tons of steam / ton of refined methanol product. Using the five-tower thermal integrated device provided by CN200910068170.2 for methanol distillation, the steam consumption of methanol distillation is about 0.75 tons of steam / ton of refined methanol product. Using the multi-effect energy-saving methanol distillation device provided by this utility model, the steam consumption of the device is less than 0.48 tons of steam / ton of refined methanol product.

[0160] This utility model provides a multi-effect energy-saving methanol distillation device, which, compared to the currently widely used four-tower methanol distillation process, achieves the following energy savings:

[0161] (1.2-0.48) / 1.2×100%≈60%

[0162] It can save approximately: steam per year

[0163] (1.2-0.48) tons / ton × 1 million tons / year = 720,000 tons / year.

[0164] Based on a cost of 150 yuan per ton of steam, the annual savings in steam costs are as follows:

[0165] 720,000 tons / year × 150 yuan / ton = 108 million yuan / year.

[0166] This utility model provides a multi-effect energy-saving methanol distillation apparatus, which, compared to the five-tower integrated heat exchanger for methanol distillation provided in CN200910068170.2, achieves the following energy savings:

[0167] (0.75-0.48) / 0.75×100%≈36%

[0168] It can save approximately: steam per year

[0169] (0.75-0.48) tons / ton × 1 million tons / year = 270,000 tons / year.

[0170] Based on a cost of 150 yuan per ton of steam, the annual savings in steam costs are as follows:

[0171] 270,000 tons / year × 150 yuan / ton = 40.5 million yuan / year.

[0172] This invention provides a multi-effect, energy-saving methanol distillation apparatus that can significantly reduce operating energy consumption. It can be used in the distillation processes of various methanol solvent recovery and methanol synthesis units to produce national standard premium-grade methanol, US standard AA-grade methanol, or other specifications of methanol products. It overcomes the shortcomings of existing technologies, reducing the steam consumption per unit volume of refined methanol to below 0.48, demonstrating significant practicality and economic benefits, and showing broad application prospects.

[0173] Application Example 2:

[0174] like Figure 3 As shown, it is Figure 2 An evolved process method, relatively Figure 2 The provided process involves a five-effect thermal integration among the five distillation columns. The top vapor phase of the fourth distillation column T340 serves as the heat source for the bottom of the third distillation column T330, providing the required heat for T330. The top vapor phase of the third distillation column T330 serves as the heat source for the bottom of the light component removal column T300, providing the required heat for T300. The top vapor phase of the light component removal column T300 serves as the heat source for the bottom of the second distillation column T320, providing the required heat for T320. The top vapor phase of the second distillation column T320 serves as the heat source for the bottom of the first distillation column T310, providing the required heat for T310.

[0175] Application Example 3:

[0176] like Figure 4 As shown, it is Figure 3 An evolved process method, relatively Figure 3 The provided process involves moving the light component removal column T300 between the fourth distillation column T340 and the third distillation column T330: the overhead vapor phase of the fourth distillation column T340 serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300; the overhead vapor phase of the light component removal column T300 serves as the heat source for heating the reboiler of the third distillation column T330, providing the required heat for T330; the overhead vapor phase of the third distillation column T330 serves as the heat source for heating the reboiler of the second distillation column T320, providing the required heat for T320; and the overhead vapor phase of the second distillation column T320 serves as the heat source for heating the reboiler of the first distillation column T310, providing the remaining required heat for T310.

[0177] Application Example 4:

[0178] like Figure 5 As shown, it is Figure 3 An evolved process method, relatively Figure 3The provided process involves moving the light component removal column T300 between the second distillation column T320 and the first distillation column T310: the overhead vapor phase of the fourth distillation column T340 serves as the heat source for heating the reboiler of the third distillation column T330, providing the required heat for the third distillation column T330; the overhead vapor phase of the third distillation column T330 serves as the heat source for heating the reboiler of the second distillation column T320, providing the required heat for the second distillation column T320; the overhead vapor phase of the second distillation column T320 serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for the light component removal column T300; and the overhead vapor phase of the light component removal column T300 serves as the heat source for heating the reboiler of the first distillation column T310, providing the required heat for the first distillation column T310.

[0179] Application Example 5:

[0180] like Figure 6 As shown, it is Figure 3 An evolved process method, relatively Figure 3 The provided process involves the following steps after the light component removal column T300 is moved to the first distillation column T310: the vapor phase from the top of the fourth distillation column T340 serves as the heat source for the reboiler of the third distillation column T330, providing the required heat for T330; the vapor phase from the top of the third distillation column T330 serves as the heat source for the reboiler of the second distillation column T320, providing the required heat for T320; the vapor phase from the top of the second distillation column T320 serves as the heat source for the reboiler of the first distillation column T310, providing the required heat for T310; and the vapor phase from the top of the first distillation column T310 serves as the heat source for the reboiler of the light component removal column T300, providing the required heat for T300.

[0181] Application Example 6:

[0182] like Figure 7 As shown, it is Figure 4 An evolved process method, relatively Figure 4 The provided process involves the following: the vapor phase from the top of the fourth distillation column T340 is divided into two streams. One stream serves as the heat source for heating the reboiler of the third distillation column T330, providing a portion of the required heat for T330. The other stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300. The vapor phase from the top of the light component removal column T300 also serves as the heat source for heating the reboiler of the third distillation column T330, providing the remaining required heat for T330.

[0183] Application Example 7:

[0184] like Figure 8 As shown, it is Figure 3 An evolved process method, relatively Figure 3The provided process involves the top vapor phase of the third distillation column T330 being divided into two streams. One stream serves as the heat source for heating the reboiler of the second distillation column T320, providing a portion of the required heat for T320. The other stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300. The top vapor phase of the light component removal column T300 also serves as the heat source for heating the reboiler of the second distillation column T320, providing the remaining required heat for T320.

[0185] Application Example 8:

[0186] like Figure 9 As shown, it is Figure 5 An evolved process method, relatively Figure 5 The provided process involves the following: the vapor phase at the top of the second distillation column T320 is divided into two streams. One stream serves as the heat source for heating the bottom of the first distillation column T310, providing a portion of the required heat for T310. The other stream serves as the heat source for heating the bottom of the light component removal column T300, providing the required heat for T300. The vapor phase at the top of the light component removal column T300 also serves as the heat source for heating the bottom of the first distillation column T310, providing the remaining required heat for T310.

[0187] Application Example 9:

[0188] like Figure 10 As shown, it is Figure 2 An evolved process method, relatively Figure 2 The provided process involves the following: the overhead vapor from the fourth distillation column T340 is divided into two streams. One stream serves as the heat source for heating the reboiler of the third distillation column T330, providing the required heat for T330. The other stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the required heat for T300. The overhead vapors from the third distillation column T330 and the light component removal column T300 serve as the heat sources for heating the reboiler of the second distillation column T320, respectively, providing the required heat for T320.

[0189] Application Example 10:

[0190] like Figure 11 As shown, it is Figure 2 An evolved process method, relatively Figure 2 The provided process involves external heat sources heating the reboils of the fourth distillation column T340 and the light component removal column T300; the overhead vapor phases of the fourth distillation column T340 and the light component removal column T300 are used as heat sources to heat the reboiler of the third distillation column T330, providing the required heat for the third distillation column T330.

[0191] Application Example 11:

[0192] like Figure 12 As shown, it is Figure 2An evolved process method, relatively Figure 2 The provided process involves the top gas phase of the second distillation column T320 being divided into two streams. One stream serves as the heat source for heating the bottom of the first distillation column T310, providing the required heat for the first distillation column T310. The other stream serves as the heat source for heating the bottom of the light component removal column T300, providing the required heat for the light component removal column T300.

[0193] Application Example 12:

[0194] like Figure 13 As shown, it is Figure 2 An evolved process method, relatively Figure 2 The provided process indicates that the fourth distillation column T340 does not use a partition structure, but adopts a conventional partitionless structure. The recovered ethanol 40 is collected above the feed inlet of the fourth distillation column T340, and fusel oil 33 is collected below the feed inlet. The bottom material of the fourth distillation column T340 is collected as wastewater 35.

[0195] Application Example 13:

[0196] like Figure 14 As shown, it is Figure 2 An evolved process method, relatively Figure 2 The provided process involves adding a stripping tower T340S. The fourth distillation tower T340 does not use a partition structure, but adopts a conventional partitionless structure. The side stream liquid material 42 of the fourth distillation tower T340 enters the top of the stripping tower T340S, and the top gaseous material 43 of the stripping tower T340S returns to the fourth distillation tower T340. The bottom of the stripping tower T340S is used to recover ethanol 40.

[0197] Application Example 14:

[0198] like Figure 15 As shown, it is Figure 2 An evolved process method, relatively Figure 2 The provided process adds a recovery tower T350, and the fourth distillation tower T340 does not use a partition structure, but adopts a conventional partitionless structure; the recovery tower T350 can use the top gas phase of the first distillation tower T310, the second distillation tower T320, or the fourth distillation tower T340 as a heat source, or use an external heat source.

[0199] Application Example 15:

[0200] like Figure 16 As shown, it is Figure 4 An evolved process method, relatively Figure 4The provided process involves adding a light component removal distillation column T300D to the light component removal column T300. This column shares the reboiler and reboiler E3001 with the light component removal column T300. The overhead vapors from both columns T300 and T300D serve as the heat source for heating the reboiler of the third distillation column T330, providing the necessary heat. Refined methanol is collected from the top of column T300D. Using this process, processing the same crude alcohol feedstock as in Example 1, and producing the same AA grade methanol, the steam consumption can be lower than 0.398 tons of steam per ton of refined methanol.

[0201] Application Example 16:

[0202] like Figure 17 As shown, it is Figure 4 An evolved process method, relatively Figure 4 The provided process involves a light component removal column T300 connected in parallel with a fifth distillation column T360. The overhead vapor from the fourth distillation column T340 is split into two streams: one stream serves as the heat source for heating the reboiler of the light component removal column T300, providing the necessary heat; the other stream serves as the heat source for heating the reboiler of the fifth distillation column T360, providing the necessary heat. The overhead vapor from both the light component removal column T300 and the fifth distillation column T360 serves as the heat source for heating the reboiler of the third distillation column T330, providing the necessary heat. Refined methanol is collected from the top of the fifth distillation column T360.

[0203] Application Example 17:

[0204] like Figure 18 As shown, it is Figure 4 An evolved process method, relatively Figure 4 The provided process involves a partitioned column structure at the top of the light component removal column T300. Partition two (S300) divides the upper part of the light component removal column T300 into a pre-distillation side R300 and a methanol distillation side L300. The vapor phases at the top of both the pre-distillation side R300 and the methanol distillation side L300 serve as the heat source for heating the bottom of the third distillation column T330, providing the required heat for the third distillation column T330. Refined methanol is collected from the top of the methanol distillation side L300. The lower part and bottom of the light component removal column T300 are conventional partitionless structures.

[0205] Application Example 18:

[0206] like Figure 19 As shown, it is Figure 2 An evolved process method, relatively Figure 2The provided process allows the light component removal column T300, the first distillation column T310, the second distillation column T320, and the third distillation column T330 to utilize integrated heating, while also employing external heating sources to provide heat to the column reboilers. These external heating sources can be fresh steam, hot water, thermal oil, or other low-grade heat sources within the system: T300 is heated via E3003 using other low-grade heat sources (low-pressure steam, hot water, thermal oil, or other low-grade heat sources within the system); T310 is heated via E3105 using other low-grade heat sources (low-pressure steam, hot water, thermal oil, or other low-grade heat sources within the system); T320 is heated via E3203 using other low-grade heat sources (low-pressure steam, hot water, thermal oil, or other low-grade heat sources within the system); and T330 is heated via E3303 using other low-grade heat sources (low-pressure steam, hot water, thermal oil, or other low-grade heat sources within the system). Each column can simultaneously or separately use the aforementioned other low-grade heat sources to heat the column or the column bottom.

[0207] This invention provides a multi-effect, energy-saving methanol distillation process apparatus that can significantly reduce operating energy consumption. The entire apparatus includes at least five distillation columns: a light component removal column T300, a first distillation column T310, a second distillation column T320, a third distillation column T330, and a fourth distillation column T340, along with their supporting equipment. It can be used in the distillation processes of various methanol solvent recovery and methanol synthesis units to produce national standard superior-grade methanol, US standard AA-grade methanol, or other specifications of methanol products. It overcomes the shortcomings of existing technologies, reducing the steam consumption per unit volume of refined methanol to below 0.48, demonstrating significant practicality and economic benefits, and showing broad application prospects.

[0208] The embodiments are described in detail below. Those skilled in the art can make appropriate modifications, alterations, and combinations based on the methods provided by this utility model to achieve the same technology. It should be particularly noted that all such modifications, alterations, and recombinations of the process flow provided by this utility model are obvious to those skilled in the art and are considered to be within the spirit, scope, and content of this utility model.

Claims

1. A multi-effect energy-saving methanol distillation apparatus, characterized in that: It mainly includes five distillation columns: a light component removal column (T300), a first distillation column (T310), a second distillation column (T320), a third distillation column (T330), and a fourth distillation column (T340), as well as connecting pipelines; The raw material crude methanol supply pipeline is connected to the cold side inlet of the feed methanol preheater (E3403) and the feed wastewater preheater (E3404), respectively. The cold-side outlets of the methanol feed preheater (E3403) and the wastewater feed preheater (E3404) are connected to the middle of the light component removal tower (T300); the top of the light component removal tower (T300) is connected to the hot-side inlet of the first distillation column feed preheater (E3101), and the hot-side condensate outlet of the first distillation column feed preheater (E3101) is connected to the top of the light component removal tower (T300). The hot-side non-condensable gas of the first distillation column feed preheater (E3101) is... The outlet is connected to the non-condensable gas discharge pipeline; the bottom of the light component removal tower (T300) is connected to the tube-side inlet of the reboiler (E3001) of the light component removal tower and the cold-side inlet of the feed preheater (E3101) of the first distillation tower, respectively; the tube-side outlet of the reboiler (E3001) of the light component removal tower is connected to the bottom of the light component removal tower (T300); and the cold-side outlet of the feed preheater (E3101) of the first distillation tower is connected to the feed inlet in the middle of the first distillation tower (T310). The top of the first distillation column (T310) is connected to the first distillation column condenser (E3103). The condensate outlet of the first distillation column condenser (E3103) is connected to the top of the first distillation column (T310) and the hot-side inlet of the feed methanol preheater (E3403). The middle feed inlet of the first distillation column (T310) is connected to the cold-side outlet of the feed preheater (E3101). The bottom of the first distillation column (T310) is connected to the tube-side inlet of the first distillation column reboiler (E3102) and the second distillation column (T320). The tube-side outlet of the first distillation column reboiler (E3102) is connected to the bottom of the first distillation column (T310). The top of the second distillation column (T320) is connected to the shell side of the reboiler (E3102) of the first distillation column. The condensate outlet of the shell side of the reboiler (E3102) of the first distillation column is connected to the top of the second distillation column (T320) and the hot-side inlet of the feed methanol preheater (E3403). The bottom of the second distillation column (T320) is connected to the tube side inlet of the reboiler (E3201) of the second distillation column and the third distillation column (T330). The tube side outlet of the reboiler (E3201) of the second distillation column is connected to the bottom of the second distillation column (T320). The top of the third distillation column (T330) is connected to the shell side of the reboiler (E3001) of the light component removal column and the shell side of the reboiler (E3201) of the second distillation column. The condensate outlet of the shell side of the reboiler (E3001) of the light component removal column and the condensate outlet of the shell side of the reboiler (E3201) of the second distillation column are connected to the top of the third distillation column (T330) and the hot-side inlet of the methanol feed preheater (E3403), respectively. The bottom of the third distillation column (T330) is connected to the tube side inlet of the reboiler (E3301) of the third distillation column and the fourth distillation column (T340). The top of the fourth distillation column (T340) is connected to the shell side of the reboiler (E3301) of the third distillation column. The condensate outlet of the shell side of the reboiler (E3301) of the third distillation column is connected to the top of the fourth distillation column (T340) and the hot-side inlet of the feed methanol preheater (E3403), respectively. The bottom of the methanol stripping side (L340) of the fourth distillation column (T340) is connected to the tube side inlet of the methanol stripping side reboiler (E3401) of the fourth distillation column and the hot-side inlet of the feed wastewater preheater (E3404), respectively. The tube side outlet of the methanol stripping side reboiler (E3401) of the fourth distillation column is connected to the fourth distillation column. The methanol stripping side (L340) of the fourth distillation column (T340) has a bottom; the side feed line near the feed of the methanol stripping side (L340) of the fourth distillation column (T340) is connected to the hot side inlet of the fusel oil cooler (E3407); the bottom of the ethanol distillation side (R340) of the fourth distillation column (T340) is connected to the tube side inlet of the reboiler (E3402) and the hot side inlet of the ethanol cooler (E3408) of the fourth distillation column (T340); the tube side outlet of the reboiler (E3402) of the ethanol distillation side of the fourth distillation column is connected to the bottom of the ethanol distillation side (R340) of the fourth distillation column (T340); The hot-side outlet of the feed methanol preheater (E3403) is connected to the hot-side inlet of the methanol product cooler (E3405), and the hot-side outlet of the methanol product cooler (E3405) is connected to the methanol product outlet pipeline. The hot-side outlet of the feed wastewater preheater (E3404) is connected to the hot-side inlet of the wastewater cooler (E3406). The hot-side outlet of the wastewater cooler (E3406) is connected to the top of the light component removal tower (T300) and the wastewater discharge pipeline, respectively. The hot-side outlet of the fusel oil cooler (E3407) is connected to the fusel oil product collection pipeline. The hot-side outlet of the ethanol cooler (E3408) is connected to the ethanol product collection pipeline.

2. The apparatus according to claim 1, characterized in that: The lower part of the fourth distillation column (T340) adopts a partition column structure. The partition (S340) divides the lower part of the fourth distillation column (T340) into a methanol stripping side (L340) and an ethanol distillation side (R340) to achieve the following: wastewater (35) is discharged from the bottom of the methanol stripping side (L340) of the fourth distillation column (T340); fusel oil with very low methanol and ethanol content is collected from the feed inlet of the methanol stripping side (L340) of the fourth distillation column (T340) via a side stream (33); and recovered ethanol product (40) is collected from the bottom of the ethanol distillation side (R340) of the fourth distillation column (T340).

3. The apparatus according to claim 1, characterized in that... The fourth distillation column (T340) does not use a partition structure, but adopts a conventional partitionless structure in order to achieve the following: ethanol (40) is collected above the feed inlet of the fourth distillation column (T340), fusel oil (33) is collected below the feed inlet, and the bottom material of the fourth distillation column (T340) is collected as wastewater (35).

4. The apparatus according to claim 1, characterized in that: Add a stripping tower (T340S), and the fourth distillation tower (T340) does not use a partition structure, but adopts a conventional partitionless structure; in order to achieve: the side stream liquid material (42) of the fourth distillation tower (T340) enters the top of the stripping tower (T340S), the top gaseous material (43) of the stripping tower (T340S) returns to the fourth distillation tower (T340), and the bottom of the stripping tower (T340S) is used to recover ethanol (40).

5. The apparatus according to claim 1, characterized in that: Add a recovery tower (T350), and the fourth distillation tower (T340) does not use a partition structure, but adopts a conventional partitionless structure; so that the recovery tower (T350) can use the top gas phase of the second distillation tower (T320), the third distillation tower (T330), or the fourth distillation tower (T340) as a heat source, or use an external heat source.

6. The apparatus according to claim 2, characterized in that... A second light component removal distillation column (T300D) is added around the light component removal column (T300) to share the reboiler and reboiler (E3001) of the light component removal column (T300). The overhead vapor phases of both the light component removal column (T300) and the light component removal distillation column (T300D) are used as the heat source for heating the reboiler of the third distillation column (T330) to provide the required heat. Refined methanol is collected from the top of the light component removal distillation column (T300D).

7. The apparatus according to claim 2, characterized in that: A fifth distillation column (T360) is connected in parallel with a light component removal column (T300) to achieve the following: the vapor phase at the top of the fourth distillation column (T340) is divided into two streams. One stream serves as the heat source for heating the bottom of the light component removal column (T300), providing the required heat for the light component removal column (T300). The other stream serves as the heat source for heating the bottom of the fifth distillation column (T360), providing the required heat for the fifth distillation column (T360). The vapor phases at the top of both the light component removal column (T300) and the fifth distillation column (T360) serve as the heat source for heating the bottom of the third distillation column (T330), providing the required heat for the third distillation column (T330). Refined methanol product is collected from the top of the fifth distillation column (T360).

8. The apparatus according to claim 2, characterized in that: The upper part of the light component removal column (T300) adopts a partitioned column structure. Partition two (S300) divides the upper part of the light component removal column (T300) into a pre-distillation side (R300) and a methanol distillation side (L300). This allows the overhead vapor phases of both the pre-distillation side (R300) and the methanol distillation side (L300) to serve as the heat source for heating the bottom of the third distillation column (T330), providing the required heat for the third distillation column (T330). Refined methanol product is collected from the top of the methanol distillation side (L300). The lower part and bottom of the light component removal column (T300) have a conventional partitionless structure.

9. The apparatus according to claim 1, characterized in that... Typical operating conditions for each tower are as follows: The operating pressure range at the top of the light component removal tower (T300) is 60–300 kPa; The operating pressure range at the top of the first distillation column (T310) is 25–150 kPa; The operating pressure range at the top of the second distillation column (T320) is 60–300 kPa; The operating pressure range at the top of the third distillation column (T330) is 100–600 kPa; The operating pressure range at the top of the fourth distillation column (T340) is 250–1300 kPa.

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