A device and method for recovering methanol and ethanol by coupling methanol rectification with ethylene glycol rectification

Abstract

This invention relates to an apparatus and method for recovering methanol and ethanol through methanol distillation coupled with ethylene glycol distillation. The method includes the following steps: collecting fusel oil from the side stream of the atmospheric distillation column, cooling it, and adding alkali to obtain alkali-treated fusel oil; mixing the alkali-treated fusel oil with the feed from the ethylene glycol dehydration column to obtain pretreated fusel oil; the pretreated fusel oil entering the ethylene glycol dehydration column from the middle section, and collecting fuel ethanol from the side stream of the middle section and methanol from the top of the column. This method recovers methanol and ethanol with low modification costs and high recovery rates without excessive site occupation or the need for new construction projects, thus generating economic benefits.

Description

Technical Field

[0001] This invention relates to the field of methanol and ethanol recovery technology, and specifically to an apparatus and method for recovering methanol and ethanol by methanol distillation coupled with ethylene glycol distillation. Background Technology

[0002] The products of coal-to-methanol plants contain ethanol. Early methanol distillation used a three-tower design, but there was no process system for removing ethanol from the distillation products. The crude methanol synthesized from methanol generally contains 500-3000 ppm of ethanol, which accumulates in the system, resulting in a high ethanol content in the methanol product. As quality requirements have increased, the small amount of ethanol in the methanol product has begun to affect the selling price of methanol, especially in the later stages of catalyst production, where the ethanol content seriously affects the quality of the methanol product. Usually, the methanol distillation fusel oil with a high ethanol content is collected from the side stream. Because the ethanol content in the methanol distillation fusel oil is low, recovery is difficult, and most of it is discharged as fusel oil. The fusel oil is difficult to treat as hazardous waste. In the existing 300,000-ton / year three-tower distillation unit, the fusel oil collected from the side stream (containing 50% methanol and 49% water) is generally pumped and sent to the boiler for co-firing. Half of the methanol in the fusel oil is wasted, and it also affects the boiler combustion conditions, reduces boiler thermal efficiency, and exacerbates boiler corrosion.

[0003] Currently, other companies' methanol three-tower distillation units all recover methanol from methanol distillation fusel oils by building new recovery towers. However, the cost of building new methanol recovery tower units is relatively high (investment of about 4 million yuan). In the existing compact plant area, space is tight, and it is difficult to build new tower equipment, resulting in a long construction period. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an apparatus and method for recovering methanol and ethanol through methanol distillation coupled with ethylene glycol distillation. The aim is to recover methanol and ethanol with low modification costs and high recovery rates without occupying excessive space or requiring new construction projects, thereby generating economic benefits from the products.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A method for recovering methanol and ethanol by coupling methanol distillation with ethylene glycol distillation includes a methanol distillation stage and an ethylene glycol distillation stage. The methanol distillation stage includes atmospheric distillation using a methanol distillation column, and the ethylene glycol distillation stage includes distillation using an ethylene glycol dehydration column. The specific coupling steps are as follows:

[0007] Step 1) Side stream extraction: fusel oil is extracted from the side stream of the methanol distillation atmospheric column, cooled, and alkali is added to obtain alkali-added fusel oil;

[0008] The purpose of adding alkali here is to remove acidic substances from crude methanol, so that the acidic substances react with the alkali to form salt, thereby preventing the generation of distillation gas phase and reducing impurities in distillation;

[0009] Step 2) Coupling treatment: The alkali-added fusel oil obtained in step 1) is mixed with the feed from the ethylene glycol dehydration tower to obtain pretreated fusel oil;

[0010] The purpose here is to ensure that the materials processed in the next step are uniform and consistent, so as to avoid adverse effects caused by concentration gradients.

[0011] Step 3) Material recovery: The pretreated fusel oil obtained in step 2) is fed into the ethylene glycol dehydration tower from the middle section of the tower. Fuel ethanol is collected from the side stream in the middle section of the ethylene glycol dehydration tower and methanol is collected from the top of the tower.

[0012] The side stream of the methanol distillation atmospheric column is cooled to below 40°C;

[0013] The fuel ethanol drawn from the middle side stream of the ethylene glycol dehydration tower has a purity of 85%, and the methanol drawn from the top of the tower has a purity of more than 99.5%.

[0014] Furthermore, the methanol distillation atmospheric tower is equipped with a side-stream outlet, which, together with the existing side-stream outlet pipeline, produces fusel oil. Adding a side-stream outlet to the existing side-stream outlet pipeline can improve the separation ratio of ethanol, thereby further enhancing the purity of coal-to-methanol products.

[0015] Furthermore, the pH value of the alkali-added fusel oil is 7-8, and the pH value is used to characterize whether the acid in the alkali-added fusel oil has been completely neutralized.

[0016] Furthermore, the methanol recovered in step three is transported to the methanol intermediate tank of the ethylene glycol production line for use in the ethylene glycol synthesis process and the low-temperature methanol washing process.

[0017] The methanol recovered in step three is transported to the methanol intermediate tank of the ethylene glycol production line for use in the ethylene glycol synthesis process and the low-temperature methanol washing process. The recovered methanol does not reach the purity of the superior grade, but it can be used in the ethylene glycol synthesis process and the low-temperature methanol washing process. Its use does not affect the purity and yield of ethylene glycol, thereby saving the refined methanol originally used in the ethylene glycol synthesis process and the low-temperature methanol washing process. The refined methanol replaced by the recovered methanol has high economic value.

[0018] Existing ethylene glycol production lines are all designed in a modular layout. Before coupling, the methanol recovered by the ethylene glycol dehydration tower was mainly transported to the crude ethylene glycol intermediate storage tank within the same block due to the small recovery flow rate. After being mixed with crude ethylene glycol, it entered the ethylene glycol distillation system as a distillation buffer. During the production process, it would be discharged and consumed due to production testing, maintaining pressure stability, and venting gas. However, impurities in the recovered methanol would accumulate in the ethylene glycol distillation tower, and after accumulating to a certain extent, it would cause the ethylene glycol distillation to fail.

[0019] Many entities in this field possess both coal-to-methanol and ethylene glycol production lines, but none couple methanol distillation with ethylene glycol distillation. Coupling increases the amount of recovered methanol, leading to an increase in the amount of recovered methanol added during ethylene glycol distillation. This results in faster accumulation of impurities in the ethylene glycol distillation column, making it easier for the ethylene glycol distillation to fail.

[0020] The present invention transports the recovered methanol to the methanol intermediate tank located in other ethylene glycol production lines for use in the ethylene glycol synthesis process and the low-temperature methanol washing process. On the one hand, it is used to make up for the consumption of refined methanol, and on the other hand, it allows the recovered methanol to return to the front of the ethylene glycol synthesis process and participate in the intermediate reaction process. This removes impurities from the recovered methanol during the intermediate reaction process, avoids the accumulation of impurities in the distillation column, and makes the ethylene glycol distillation process more stable.

[0021] An apparatus for recovering methanol and ethanol by coupling methanol distillation with ethylene glycol distillation is disclosed. The methanol distillation atmospheric column of the methanol distillation production line is equipped with a methanol distillation side-stream outlet pipeline. This side-stream outlet pipeline is connected to a fusel oil cooler of the methanol distillation production line. The fusel oil cooler is connected to a fusel oil storage tank. The outlet pipe of the fusel oil storage tank and the outlet pipe of the alkali tank of the methanol distillation production line are jointly connected to a mixing pipeline. A first static mixer is installed on the mixing pipeline. The end of the mixing pipeline is connected to an ethylene glycol dehydration tower via a coupling pipeline, which is connected to the conveying pipeline of the ethylene glycol dehydration tower of the ethylene glycol distillation production line. A second static mixer is installed on the coupling pipeline.

[0022] Furthermore, the methanol distillation side-line production pipeline includes a fusel oil production pipeline and an extended production pipeline, wherein the extended production pipeline is located above the fusel oil production pipeline.

[0023] Furthermore, in the methanol distillation atmospheric pressure column, a side outlet is added to every other tray below the feed inlet. Multiple side outlets are connected to a conveying pipeline, and the conveying pipelines connected by multiple side outlets are merged and connected to extend the outlet pipeline.

[0024] Furthermore, the number of the additional side-line sampling outlets is four.

[0025] Furthermore, a first side-line extraction control valve is provided on the fusel oil extraction pipeline, and a second side-line extraction control valve is provided on the extended extraction pipeline. The first side-line extraction control valve and the second side-line extraction control valve are linked together.

[0026] Furthermore, the mixing pipeline is equipped with a fusel alcohol pH meter, a fusel alcohol flow meter, and a fusel alcohol flow regulating valve.

[0027] The beneficial effects of the present invention through the above technical solution are as follows:

[0028] This invention recovers methanol and ethanol with low modification costs and high recovery rates without occupying too much space or requiring new construction projects, thereby improving the quality of methanol and ensuring the quality of coal-based methanol products.

[0029] This invention only requires the addition of four side-stream outlets, a pH meter, a fusel oil flow meter, a fusel oil feed regulating valve, a second static mixer, and corresponding conveying pipelines to complete the transfer and processing of fusel oil produced from the side-stream of the coal-to-methanol plant. It does not require new construction projects or complicated approval and construction processes, and can streamline the safety assessment and environmental assessment processes. The fusel oil produced by the coal-to-methanol plant can be processed and recovered efficiently, generating economic benefits.

[0030] This invention couples the fusel oil treatment of coal-to-methanol with the dehydration tower of ethylene glycol. The produced methanol is then applied to the ethylene glycol production line. This transforms the hazardous waste treatment process, which originally required a large investment, into an investment that is negligible, requiring only a small amount of steam. Furthermore, it improves the purity of the coal-to-methanol process and reduces the cost of the ethylene glycol process. By using a simple device to couple the two production lines, the core competitiveness of both products is enhanced.

[0031] This invention improves the purity of coal-based methanol products and reduces the cost of ethylene glycol products during hazardous waste treatment, while also enabling ethylene glycol production lines to save on refined methanol, recover ethanol, and sell it externally, resulting in significant economic benefits. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the present invention.

[0033] The attached diagram is labeled as follows: 1. Methanol distillation atmospheric column; 2. Second side-stream control valve; 3. First side-stream control valve; 4. Fusel cooler; 5. Fusel storage tank; 6. Fusel transfer pump; 7. First static mixer; 8. Fusel pH meter; 9. Fusel flow meter; 10. Fusel flow regulating valve; 11. Alkali tank; 12. Alkali pump; 13. Alkali addition valve; 14. Feed flow meter; 15. Feed regulating valve; 16. Second static mixer; 17. Ethylene glycol dehydration column; 18. Reboiler; 19. Top cooler; 20. Reflux tank; 21. Reflux pump; 22. Ethanol product cooler; 23. Bottom wastewater cooler; 24. Bottom pump. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0035] It should be noted that the directional terms "front", "back", "left", "right", "up", "down", "bottom", and "top" used in the following description refer to the directions shown in the attached diagram, while the terms "inside" and "outside" refer to the directions toward or away from the geometric center of a specific component, respectively.

[0036] As attached Figure 1 As shown, a method for recovering methanol and ethanol by methanol distillation coupled with ethylene glycol distillation includes the following steps:

[0037] Step 1) Side stream extraction: Fusel is extracted from the side stream of the methanol distillation atmospheric column 1 of the methanol production line, cooled to below 40°C by the fusel oil cooler 4 of the methanol distillation production line, and then mixed with alkali to form alkali-added fusel oil.

[0038] Step 2) Coupling process: The alkali-added fusel alcohol is mixed with the feed of the ethylene glycol dehydration tower 17 of the ethylene glycol distillation production line to form a pretreated fusel alcohol;

[0039] Step 3) Material recovery: The pretreated fusel oil enters the ethylene glycol dehydration tower 17 from the middle section, and 85% fuel ethanol is collected from the side stream of the middle section of the ethylene glycol dehydration tower 17, while methanol with a purity greater than 99.5% is collected from the top of the tower.

[0040] The methanol distillation atmospheric tower 1 of the methanol production line is equipped with a side outlet. The fusel oil extracted from this side outlet is transported together with the fusel oil extracted from the original side outlet pipeline through a conveying pipeline for cooling and alkali treatment.

[0041] The pH value of the added alkali fusel oil is 7-8.

[0042] An apparatus for recovering methanol and ethanol by coupled methanol distillation and ethylene glycol distillation is disclosed. The methanol distillation atmospheric column 1 of the methanol distillation production line is equipped with a methanol distillation side-stream outlet pipeline. This side-stream outlet pipeline connects to a fusel oil cooler 4 of the methanol distillation production line. The fusel oil cooler 4 connects to a fusel oil storage tank 5. The outlet pipe of the fusel oil storage tank 5 and the outlet pipe of the alkali tank 11 of the methanol distillation production line are connected to a mixing pipeline. A fusel oil transfer pump 6 is installed on the outlet pipe of the fusel oil storage tank 5, and an alkali pump 12 and an alkali addition and adjustment valve 13 are installed on the outlet pipe of the alkali tank 11. A first static mixer 7 is provided on the mixing pipeline. The end of the mixing pipeline is connected to the conveying pipeline of the ethylene glycol dehydration tower of the ethylene glycol distillation production line via a coupling pipeline to the ethylene glycol dehydration tower 17. The conveying pipeline of the ethylene glycol dehydration tower is provided with a feed flow meter 14 and a feed regulating valve 15. The coupling pipeline is provided with a second static mixer 16. The ethylene glycol dehydration tower 17 is provided with auxiliary mechanisms such as a reboiler 18, a tower top cooler 19, a reflux tank 20, a reflux pump 21, an ethanol collection cooler 22, a tower bottom wastewater cooler 23, and a tower bottom pump 24.

[0043] This invention only requires the addition of a pH meter, a fusel oil flow meter, a fusel oil feed regulating valve, a second static mixer 16, and corresponding conveying pipelines to complete the transfer processing of fusel oil extracted from the side line of the coal-to-methanol plant. It can not only recover methanol and ethanol from the fusel oil, thereby improving the purity of the methanol product from the coal-to-methanol plant and thus increasing the selling price, but also does not require new construction projects, does not occupy too much space, and the fusel oil produced by the coal-to-methanol plant can be processed and recovered efficiently, generating economic benefits.

[0044] The methanol distillation side-line production pipeline includes the original fusel oil production pipeline and a newly added extended production pipeline, with the extended production pipeline located above the fusel oil production pipeline.

[0045] The methanol distillation atmospheric tower 1 adds a side outlet every other tray below the feed inlet, for a total of 4 side outlets. Each of the 4 side outlets is connected to a conveying pipeline. The conveying pipelines connected by the 4 side outlets are merged and connected to the extended outlet pipeline. After adding multiple side outlets, the separation ratio of ethanol is improved, the purity of the coal-to-methanol product is further improved, and the competitiveness of the product is enhanced.

[0046] The fusel oil extraction pipeline is equipped with a first side-line extraction control valve 3, and the extended extraction pipeline is equipped with a second side-line extraction control valve 2. The first side-line extraction control valve 3 and the second side-line extraction control valve 2 are linked to adjust the proportion of side-line extracted gas from the methanol distillation atmospheric tower, so that as much ethanol as possible is extracted, while not affecting the normal operation of the ethylene glycol dehydration tower.

[0047] The mixing pipeline is equipped with a fusel oil pH meter 8, a fusel oil flow meter 9, and a fusel oil flow regulating valve 10, which are used to monitor the flow rate and pH value of the material delivered to the ethylene glycol dehydration tower, and to ensure the normal operation of the ethylene glycol dehydration tower.

[0048]

[0049]

[0050] The table above shows the operating parameters of the ethylene glycol dehydration tower before and after coupling.

[0051]

[0052] The table above shows the feed composition of the ethylene glycol dehydration tower before and after coupling.

[0053] As shown in the two tables above, the operating status of the ethylene glycol dehydration tower changes as follows: the load of the ethylene glycol dehydration tower increases from 40% to 106% (below 120% is the normal operating state), the tower pressure increases from 5 kPa to 8 kPa, the reflux rate increases from 6 cubic meters per hour to 10 cubic meters per hour, and the reflux ratio decreases from 10.01 to 6.18. It can be seen that all operating parameters are within the normal operating range of the ethylene glycol dehydration tower, and the coupling does not exceed the normal operating range of the ethylene glycol dehydration tower.

[0054] The recovery of various products is as follows: Before and after coupling, the methanol yield in the feed increased by 2 percentage points, the ethanol yield remained unchanged, the methanol yield from the top of the column increased by 217.3%, and the ethanol yield from the side stream increased by 14.3%. It can be seen that the recovery of various products was significantly improved after coupling. The crude methanol synthesized from methanol generally contains 500-3000 ppm of ethanol. Even if the cumulative maximum concentration is calculated at 3000 ppm, the concentration of ethanol is only 0.3% of the fusel oil. Such a low concentration is very difficult to separate by distillation. In the existing technology, even newly built recovery equipment can only recover a portion of methanol from fusel oil, while the rest is treated as hazardous waste. However, this invention couples it to the ethylene glycol dehydration tower, which increases the ethanol concentration before distillation, making it easier to separate and purify. This allows this portion of ethanol to be successfully recovered, avoiding waste. This is also the reason for the increase in the ethanol flow rate from the side stream in the table above.

[0055] The energy consumption changes before and after coupling are as follows: steam consumption increased from 3.2 tons per hour to 5.8 tons per hour, electricity consumption remained unchanged at 56.8 kWh, and circulating water consumption increased from 200 tons per hour to 350 tons per hour. That is, after coupling, the energy consumption of the ethylene glycol dehydration tower only increased the steam consumption and circulating water consumption, while the electricity consumption remained unchanged. The input of circulating water and steam is negligible compared to the recovered products, but the recovered methanol and ethanol have high economic benefits.

[0056] Based on a coal-to-methanol production line with an annual capacity of 300,000 tons, producing 2 tons of fusel oil per hour, with an ethanol concentration of 1200 ppm in the fusel oil and 200 ppm of ethanol in the refined methanol after distillation, 7961.15 tons of methanol and 188.24 tons of ethanol are recovered annually, which has significant economic benefits. In particular, the coupled treatment does not increase power consumption, but only increases the circulating water flow and steam consumption. Considering the economic benefits generated by the recovery, the energy consumption increase from the coupled treatment is negligible.

[0057] Ethylene glycol yield before coupling 98.50％ Ethylene glycol yield after coupling 98.50％ Ethylene glycol purity before coupling Premium Ethylene glycol purity after coupling Premium

[0058] The table above compares the yield and purity of ethylene glycol before and after coupling.

[0059] project Consumption Before coupling, 1 ton of ethylene glycol consumed refined methanol 30kg / t ethylene glycol Pre-coupling ethylene glycol production with added refined methanol 18t / day Low-temperature methanol wash before coupling, plus refined methanol 3t / day Methanol recovery from the dehydration tower after coupling 24t / day Methanol surplus recovered from the dehydration tower after coupling 3t / day

[0060] When operating at full capacity, the ethylene glycol production rate is 600 tons per day. The table above shows the methanol usage in the ethylene glycol production line before and after coupling.

[0061] As can be seen from the table above, before coupling, 18 tons of refined methanol needed to be added to the ethylene glycol production line and 3 tons of refined methanol needed to be added to the low-temperature methanol washing unit of coal-to-methanol production every day. After coupling, the methanol recovered from the fusel oil of coal-to-methanol production not only completely made up for the shortage of the ethylene glycol production line, but also had a surplus, which could be sold as low-quality methanol. The refined methanol saved due to coupling was sold as high-quality methanol products.

[0062] This invention relates to a method for recovering methanol and ethanol by coupling methanol distillation with ethylene glycol distillation. This method couples byproduct fusel oils from coal-to-methanol production to an ethylene glycol production line for processing. It achieves the recovery and processing steps that would otherwise require millions of dollars in other technologies, without adding new construction projects or complex approval and construction processes. Since it only involves changes to existing equipment and pipeline connections, it also simplifies safety and environmental assessments. While processing fusel oils, it not only further improves the purity of coal-to-methanol, increasing its selling price, but also provides economic benefits from the recovered ethanol. Furthermore, the recovered methanol also... This method can replace refined methanol in ethylene glycol production. As shown in the comparison table of ethylene glycol yield and purity before and after coupling, replacing refined methanol with lower-purity recovered methanol as the treatment agent in the ethylene glycol production process does not affect the purity and yield of ethylene glycol. This is unexpected by those skilled in the art. The amount of refined methanol replaced is as high as 7,600 tons per year. At the same time, using the recovered methanol in ethylene glycol production is basically free of cost, which can reduce the cost of ethylene glycol. From another perspective, the method of methanol distillation coupled with ethylene glycol distillation to recover methanol and ethanol also improves the competitiveness of ethylene glycol products.

[0063] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various modifications can be made to the technical solutions of the present invention without departing from the spirit of the present invention or the scope of disclosure.

Claims

1. A method for recovering methanol and ethanol by coupled methanol distillation and ethylene glycol distillation, comprising a methanol distillation stage and an ethylene glycol distillation stage, characterized in that, The methanol distillation stage includes atmospheric distillation using a methanol distillation atmospheric column (1), and the ethylene glycol distillation stage includes distillation using an ethylene glycol dehydration column (17). The specific coupling steps are as follows: Step 1) Side stream extraction: fusel oil is extracted from the side stream of the methanol distillation atmospheric column (1), cooled, and alkali is added to obtain alkali-added fusel oil; Step 2) Coupling treatment: The alkali-added fusel alcohol obtained in step 1) is mixed with the feed of the ethylene glycol dehydration tower (17) to obtain pretreated fusel alcohol; Step 3) Material recovery: The pretreated fusel oil obtained in step 2) enters the ethylene glycol dehydration tower (17) from the middle section of the ethylene glycol dehydration tower (17), and fuel ethanol is collected from the side stream in the middle section of the ethylene glycol dehydration tower (17) and methanol is collected from the top of the tower.

2. The method for recovering methanol and ethanol by methanol distillation coupled with ethylene glycol distillation according to claim 1, characterized in that, The methanol distillation atmospheric column (1) is equipped with a side-stream outlet, which together with the existing side-stream outlet pipeline produces fusel oil.

3. The method for recovering methanol and ethanol by methanol distillation coupled with ethylene glycol distillation according to claim 1, characterized in that, The methanol recovered in step 3) is transported to the methanol intermediate tank of the ethylene glycol production line for use in the ethylene glycol synthesis process and the low-temperature methanol washing process.

4. An apparatus for recovering methanol and ethanol by methanol distillation coupled with ethylene glycol distillation, using the method for recovering methanol and ethanol by methanol distillation coupled with ethylene glycol distillation as described in claim 1, comprising a methanol distillation production line and an ethylene glycol distillation production line, characterized in that, The methanol distillation atmospheric tower (1) of the methanol distillation production line is equipped with a methanol distillation side line outlet pipeline. The methanol distillation side line outlet pipeline is connected to the fusel oil cooler (4) of the methanol distillation production line. The fusel oil cooler (4) is connected to the fusel oil storage tank (5). The outlet pipe of the fusel oil storage tank (5) and the outlet pipe of the alkali tank (11) of the methanol distillation production line are connected to a mixing pipeline. A first static mixer (7) is provided on the mixing pipeline. The end of the mixing pipeline is connected to the ethylene glycol dehydration tower (17) of the ethylene glycol distillation production line through a coupling pipeline. A second static mixer (16) is provided on the coupling pipeline.

5. The apparatus for recovering methanol and ethanol by methanol distillation coupled with ethylene glycol distillation as described in claim 4, characterized in that, The methanol distillation side-line production pipeline includes a fusel oil production pipeline and an extended production pipeline, with the extended production pipeline located above the fusel oil production pipeline.

6. The apparatus for recovering methanol and ethanol by methanol distillation coupled with ethylene glycol distillation as described in claim 5, characterized in that, The methanol distillation atmospheric column (1) has an additional side outlet on every other tray below the feed inlet. All side outlets are higher than the fusel oil outlet pipeline. Each side outlet is connected to a conveying pipeline. The conveying pipelines connected by the multiple side outlets are merged and connected to extend the outlet pipeline.

7. The apparatus for recovering methanol and ethanol by methanol distillation coupled with ethylene glycol distillation as described in claim 6, characterized in that, The number of the additional side-line sampling outlets is 4.

8. The apparatus for recovering methanol and ethanol by methanol distillation coupled with ethylene glycol distillation as described in claim 5, characterized in that, The fusel oil extraction pipeline is equipped with a first side-line extraction control valve (3), and the extended extraction pipeline is equipped with a second side-line extraction control valve (2). The first side-line extraction control valve (3) and the second side-line extraction control valve (2) are linked together.

9. The apparatus for recovering methanol and ethanol by methanol distillation coupled with ethylene glycol distillation as described in claim 4, characterized in that, The mixing pipeline is equipped with a fusel alcohol pH meter (8), a fusel alcohol flow meter (9), and a fusel alcohol flow regulating valve (10).

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