CN214937125U

CN214937125U - System for producing ethanol by using oxalate

Info

Publication number: CN214937125U
Application number: CN202022464834.1U
Authority: CN
Inventors: 王保明; 王东辉; 李玉江; 徐长青
Original assignee: Wuzheng Engineering Shanghai Co ltd
Current assignee: Wuzheng Engineering Shanghai Co ltd
Priority date: 2020-10-30
Filing date: 2020-10-30
Publication date: 2021-11-30
Anticipated expiration: 2030-10-30

Abstract

The utility model provides a system for oxalic ester production ethanol, include: the hydrogenation reactor is used for carrying out catalytic reaction on hydrogen and oxalate to obtain a crude ethanol mixture; a methanol separation device for separating the crude ethanol mixture to obtain a mixture mainly containing methanol and a mixture containing ethanol and glycol; the methanol separation device is communicated with the hydrogenation reactor; a light component separation tower for separating a mixture containing ethanol and glycol to obtain common ethanol and freezing-grade glycol; the light component separation tower is communicated with a methanol separation device. The utility model has the characteristics of the product distribution is adjusted in a flexible way, one-way conversion rate is high, and reaction heat effectively utilizes the height etc. can adjust the product proportion according to market needs, produces different specification products, shortens production flow, and the production energy consumption reduces by a wide margin, effectively improves device economic benefits and market competition.

Description

System for producing ethanol by using oxalate

Technical Field

The utility model belongs to ester hydrogenation system ethanol field relates to a system of oxalic ester production ethanol.

Background

Ethanol is an important basic chemical raw material, is used for manufacturing acetaldehyde, ethylene, ethylamine, ethyl acetate, acetic acid, chloroethane and the like, derives a plurality of intermediates of products such as medicines, dyes, coatings, spices, synthetic rubber, detergents, pesticides and the like, and produces more than 300 products. Meanwhile, in the application of fuel energy industry, ethanol has the characteristics of low heat value, high vaporization latent heat, good anti-explosion performance, high oxygen content, easy phase separation in the presence of a small amount of water, more complete combustion, low CO emission, similar combustion performance and the like compared with common gasoline, so that the ethanol is called as 'green energy' in the 21 st century. Currently, due to non-renewable petroleum and unstable petroleum producing areas, fuel energy safety issues are drawing more and more attention on the global scale, and the popularization and application of fuel ethanol are actively carried out in all countries of the world, and 60% of ethanol production in the world is used as vehicle fuel. Therefore, the development of energy industries using alcohol as a raw material, such as ethanol and ethanol diesel, has been a major issue in the international fuel energy industry.

At present, grains are mainly used as raw materials for producing fuel ethanol, corn fuel ethanol becomes an important energy supply source in many countries, but due to the rising of the price of grains, the price of ethanol is continuously rising. At present, the price of absolute ethyl alcohol is nearly 8000 yuan/ton, so that a non-food process route is a very intelligent choice.

Patent CN1122567C discloses a method for directly producing ethanol by hydrogen and carbon monoxide synthesis. The method has the advantages of simple process route, high energy efficiency and easy scale production from the technical principle, and is an ideal synthetic route. However, 1 ton of ethanol is produced from 1.4 ton of synthesis gas in the process, the conversion rate of the synthesis gas is only 71%, the byproduct of ethanol production from the synthesis gas is water, and about 1/4 of hydrogen in the synthesis gas is lost. The product components are complex, and the crude product also needs hydrogenation and refining treatment. The development of the catalyst for directly preparing ethanol from the synthesis gas still stays in a small test stage at present, and the catalyst is expensive noble metal (rhodium and the like) catalyst, so that the problems of low reaction rate and the like exist, and the problems are technical bottlenecks which cannot be broken through at present and for a long time in the future.

SUMMERY OF THE UTILITY MODEL

The utility model aims at overcoming the shortcoming of above prior art, providing a system for oxalate production ethanol. The system has the characteristics of flexible product distribution adjustment, high single-pass conversion rate, high effective utilization of reaction heat and the like, can adjust the product proportion according to market needs, produces products with different specifications, shortens the production flow, greatly reduces the production energy consumption, and effectively improves the economic benefit and the market competitiveness of the device.

To achieve the above and other related objects, the present invention provides a system for producing ethanol from oxalate, comprising:

the hydrogenation reactor is used for carrying out catalytic reaction on hydrogen and oxalate to obtain a crude ethanol mixture;

a methanol separation device for separating the crude ethanol mixture to obtain a mixture mainly containing methanol and a mixture containing ethanol and glycol; the methanol separation device is communicated with the hydrogenation reactor;

a light component separation tower for separating a mixture containing ethanol and glycol to obtain common ethanol and freezing-grade glycol; the light component separation tower is communicated with the methanol separation device.

The utility model discloses at least one in following effect has:

1) the utility model has the characteristics of the product distribution is adjusted in a flexible way, one-way conversion rate is high, and reaction heat effectively utilizes the height etc. can adjust the product proportion according to market needs, produces different specification products, shortens production flow, and the production energy consumption reduces by a wide margin, effectively improves device economic benefits and market competition.

2) Through the utility model discloses system for oxalic ester production ethanol can obtain methyl alcohol, can be used for the outer upper reaches device raw materials of boundary area, methyl alcohol used repeatedly's process.

3) The utility model realizes the combination of catalytic reaction and special combination separation mode, realizes multi-product distribution, saves equipment investment and separation energy consumption, simplifies the flow, effectively utilizes reaction heat, uses conventional non-noble metal catalyst as the catalyst in the hydrogenation reactor, has mild reaction conditions, little corrosivity of reaction materials, less equipment investment, novel process mode and high production efficiency; the investment is low, the energy consumption is low, the catalyst is a conventional copper-based composite catalyst, and the cost is low. Meanwhile, the corrosion of the raw materials and the products is weak, so that the carbon steel can be adopted, and the investment amount is greatly reduced. The system has low operation cost, and particularly, the catalysts involved in the system are common non-noble metal catalysts, so the system has obvious advantages compared with other systems which commonly use noble metal catalysts. According to estimation, the investment of the system equipment is only 1/2 or even lower when acetic acid is directly hydrogenated to prepare ethanol, the production cost is lower than that of the conventional technology for preparing ethanol by a biological fermentation method, and the system is the most possible industrialized process route at present. The method has important significance for solving the problems that the dimethyl ether productivity is seriously excessive and the production and sale prices are seriously hung upside down at present.

4) The utility model discloses fully consider exothermic unit and with the coupling of hot unit, but greatly reduced synthesizes the energy consumption, equipment investment is few, and environment friendly, the system is simple, and economical and practical can realize the multi-product production in same system.

Drawings

Fig. 1 is a first diagram of a system for producing ethanol from oxalate according to the present invention.

Fig. 2 is a second diagram of the system for producing ethanol from oxalate according to the present invention.

Fig. 3 is a third diagram of the system for producing ethanol from oxalate according to the present invention.

Fig. 4 is a diagram of a system for producing ethanol from oxalate according to the present invention.

Reference numerals

1 hydrogenation reactor

2 methanol separation device

21 first gas-liquid separator

22 second gas-liquid separator

23 methanol recovery tower

24 flash tank

241 non-condensable gas discharging pipeline

3 light component separation tower

4 compressor

5 first heat exchanger

6 hydrogen raw material pipeline

7 oxalate raw material pipeline

8 second heat exchanger

9 Heater

10 ethylene glycol separation device

11 three-phase azeotropic rectifying tower

111 rectifying column body

1111 entrainer inlet

1112 Tower top outlet

1113 bottom outlet of tower

112 overhead condenser

113 tower kettle reboiler

114 multiphase separator

1141 light phase outlet

1142 heavy phase outlet

12 waste water tower

Detailed Description

The following description is provided for illustrative purposes, and other advantages and features of the present invention will become apparent to those skilled in the art from the following detailed description.

It should be understood that the structure, ratio, size and the like shown in the drawings attached to the present specification are only used for matching with the content disclosed in the specification, so as to be known and read by those skilled in the art, and are not used for limiting the limit conditions that the present invention can be implemented, so that the present invention has no technical essential meaning, and any structure modification, ratio relationship change or size adjustment should still fall within the scope that the technical content disclosed in the present invention can cover without affecting the function that the present invention can produce and the purpose that the present invention can achieve. Meanwhile, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for convenience of description, and are not intended to limit the scope of the present invention, and changes or adjustments of the relative relationship thereof may be made without substantial technical changes, and the present invention is also regarded as the scope of the present invention.

A system for producing ethanol from oxalate, as shown in fig. 1, comprising:

a hydrogenation reactor 1 for carrying out catalytic reaction on hydrogen and oxalate to obtain a crude ethanol mixture;

a methanol separation device 2 for separating the crude ethanol mixture to obtain a mixture mainly containing methanol and a mixture containing ethanol and glycol; the methanol separation device 2 is communicated with the hydrogenation reactor 1;

a light component separation column 3 for separating a mixture containing ethanol and ethylene glycol to obtain normal ethanol and freezing-grade ethylene glycol; the light component separation tower 3 is communicated with the methanol separation device 2.

Carrying out oxalate hydrogenation reaction in a hydrogenation reactor 1: oxalate such as dimethyl oxalate from the tower bottom of a dimethyl oxalate rectifying tower is mixed with hydrogen such as industrial hydrogen pressurized by a hydrogenation circulating compressor and then enters a hydrogenation reactor 1, and in the presence of a hydrogenation catalyst, hydrogenation reaction is carried out to generate methanol, glycol and the like, namely a crude ethanol mixture. The oxalate is dimethyl oxalate, but is not limited to dimethyl oxalate.

The methanol refining process is performed in the methanol separation device 2: the crude ethanol mixture from the hydrogenation reactor enters a methanol separation device 2, and a refined methanol material is extracted from the top of the tower and can be recycled to a carbonylation device to be used as a raw material; purge gas at the tower top can be discharged into a flash tank 24 for dealcoholization and then recycled; the bottom of the column obtained a mixture comprising ethanol and ethylene glycol.

Preparing common ethanol and freezing-grade ethylene glycol: the mixture containing ethanol and glycol from the methanol separation device enters a light component separation tower 3, and is extracted as a product at the tower top to obtain common ethanol; and extracting the tower kettle as a product to obtain the freezing-grade glycol. The concentration of the common ethanol is lower than that of the absolute ethanol, the concentration is less than 99.5 wt%, for example, the concentration is 95 wt% -98 wt%; the concentration of the refrigeration grade glycol is lower than that of the polyester grade glycol, such as 40 wt% to 60 wt%.

The hydrogenation reactor 1 may be a fixed bed reactor or a fluidized bed reactor, and more preferably a fixed bed reactor.

The hydrogenation reactor 1 can be a plate reactor, a tubular reactor or a tubular/plate composite reactor, and particularly preferably is a plate-type fixed bed reactor. When the hydrogenation reactor is a plate-type fixed bed reactor, a plate group fixing cavity is arranged at the center of the hydrogenation reactor 1, and a plate group is arranged in the plate group fixing cavity; a catalyst bed layer is arranged between the outer wall of the plate group fixing cavity and the inner wall of the hydrogenation reactor 1; the catalyst bed layer is filled with hydrogenation reaction catalyst. After the hydrogenation reaction raw material reaches the inlet temperature of the catalyst bed, the hydrogenation reaction raw material enters the catalyst bed from the top of the hydrogenation reactor 1 to carry out hydrogenation reaction; a refrigerant introduced from the outside enters the plate group fixing cavity from the bottom of the hydrogenation reactor 1 and is led out from the top of the hydrogenation reactor 1, and the reaction heat of the hydrogenation reaction is taken away by heat exchange in a counter-current process; the hydrogenation product from the bottom of the catalyst bed is led out from the bottom of the hydrogenation plate reactor 1.

The light component separation column 3 may be a packed column, a plate column, or a bubble column. When the light component separation tower 3 is a packed tower, the packing filled in the packed tower is random packing or high-efficiency regular packing. The random packing is in the shape of saddle, Raschig ring, pall ring, wheel, intalox saddle ring, sphere or column. The efficient structured packing is corrugated packing, grid packing or pulse packing.

The temperature of the hydrogenation reaction is 170-350 ℃, the reaction pressure is 1-10 MP, and the liquid hourly space velocity is 1-3 Kg/Kg.

In a preferred embodiment, the temperature of the hydrogenation reaction is 195-260 ℃.

In a preferred embodiment, the reaction pressure in the hydrogenation reactor is 5 to 8 MPa.

In a preferred embodiment, the mixing molar ratio of hydrogen to oxalate such as dimethyl oxalate is 30 to 300: 1, more preferably 60 to 250: 1.

in a preferred embodiment, the hydrogenation catalyst is selected from the group consisting of those commercially available from Shanghai Peng engineering technologies, Inc. under the trade designation MEG-803T.

In a preferred embodiment, the number of theoretical plates of the light component separation tower is 10-30, the tower top temperature is 58-90 ℃, the tower kettle temperature is 70-160 ℃, and the absolute pressure of the tower top is 5-50 KPa.

In a preferred embodiment, the overhead light component reflux ratio of the light component separation column is 0.1 to 10.

In a preferred embodiment, the overhead light component reflux ratio of the light component rectifying tower is 1-10.

In a preferred embodiment, as shown in fig. 1, the methanol separation device 2 includes:

a first gas-liquid separator 21 for subjecting the crude ethanol mixture to first gas-liquid separation; the first gas-liquid separator 21 is communicated with the hydrogenation reactor 1;

a second gas-liquid separator 22 for subjecting a part of the first gas phase obtained by the first gas-liquid separation to a second gas-liquid separation; the second gas-liquid separator 22 communicates with the first gas-liquid separator 21;

a methanol recovery column 23 for recovering methanol from the first liquid phase obtained by the first gas-liquid separation and the second liquid phase obtained by the second gas-liquid separation to obtain a mixture mainly containing methanol and a mixture containing ethanol and ethylene glycol; the methanol recovery tower 23 communicates with the first gas-liquid separator 21 and the second gas-liquid separator 22.

The gas phase part separated by the first gas-liquid separator 21 enters a second gas-liquid separator 22; the liquid phase separated by the first gas-liquid separator 21 and the liquid phase separated by the second gas-liquid separator 22 enter the methanol recovery tower 23. The mixture which is recovered from the top of the methanol recovery tower 23 and mainly comprises methanol can partially enter an outside-battery-limit oxalate device to be directly used as an outside-battery-limit esterification raw material.

The methanol recovery column 23 may be a packed column, a plate column, or a bubble column. When the methanol recovery tower 23 is a packed tower, the packing filled in the packed tower is random packing or high-efficiency regular packing. The random packing is in the shape of saddle, Raschig ring, pall ring, wheel, intalox saddle ring, sphere or column. The efficient structured packing is corrugated packing, grid packing or pulse packing.

In a preferred embodiment, 0.1 to 30% v of the gas phase separated by the first gas-liquid separator 21 is introduced into the second gas-liquid separator 22, and more preferably 0.1 to 10% v of the separated gas phase is introduced into the second gas-liquid separator 22.

In a preferred embodiment, the number of theoretical plates of the methanol recovery column 23 is 5 to 100, the top temperature is 5 to 150 ℃, the bottom temperature is 30 to 180 ℃, and the top pressure is 0.01 to 2.0 MPa.

In a preferred embodiment, the number of theoretical plates of the methanol recovery tower 23 is 10 to 40, the tower top temperature is 40 to 70 ℃, the tower bottom temperature is 80 to 180 ℃, and the operation is carried out under normal pressure or reduced pressure.

In a preferred embodiment, the reflux ratio of light components at the top of the methanol recovery column 23 is 0.1 to 10.

In a preferred embodiment, the reflux ratio of light components at the top of the methanol recovery column 23 is 0.5 to 3.

In a preferred embodiment, the methanol separation unit 2 further comprises a flash drum 24;

the flash tank 24 is communicated with the second gas-liquid separator 22, and is used for flashing a second gas phase obtained by second gas-liquid separation;

the methanol recovery tower 23 is communicated with the flash tank 24 and is used for carrying out flash evaporation on the non-condensable gas obtained by methanol recovery;

the flash tank 24 is communicated with the methanol recovery tower 23, and is used for recovering methanol from the liquid phase obtained by flash evaporation.

The second gas phase separated by the second gas-liquid separator 22 and the noncondensable gas from the top of the methanol recovery column 23 are introduced into the flash drum 24.

In a preferred embodiment, the system further comprises a compressor 4 and a first heat exchanger 5;

the first gas-liquid separator 21 is communicated with the hydrogenation reactor 1 through the compressor 4 and the first heat exchanger 5 in sequence, and is used for circulating a part of first gas phase obtained by separating the first gas-liquid to the hydrogenation reactor 1 as a catalytic reaction raw material after compression and heat exchange in sequence;

the flash tank 24 is communicated with the hydrogenation reactor 1 through the compressor 4 and the first heat exchanger 5 in sequence, and is used for circulating a part of flash vapor phase obtained by flash evaporation to the hydrogenation reactor 1 as a catalytic reaction raw material after compression and heat exchange in sequence.

The first gas phase obtained from the first gas-liquid separator 21 and the flash gas part obtained from the flash tank 24 are pressurized by the compressor 4, and then are subjected to heat exchange by the first heat exchanger 5 to be used as a catalytic reaction raw material to be circulated to the hydrogenation reactor 1.

In a preferred embodiment, the flash tank 24 is provided with a non-condensable gas discharge conduit 241 for discharging non-condensable gas.

In a preferred embodiment, the system further comprises a hydrogen feed line 6 and an oxalate feed line 7;

the hydrogen raw material pipeline 6 is communicated with the hydrogenation reactor 1 through the compressor 4 and the first heat exchanger 5 in sequence, and is used for introducing a hydrogen raw material into the hydrogenation reactor 1 after compression and heat exchange in sequence;

the oxalate raw material pipeline 7 is communicated with the hydrogenation reactor 1 through the first heat exchanger 5, and is used for introducing an oxalate raw material into the hydrogenation reactor 1 after heat exchange.

The oxalate raw material such as oxalate from a device for preparing oxalate from synthetic gas outside a battery compartment, hydrogen raw material such as industrial hydrogen from a pressurized circulating compressor and circulating gas are subjected to heat exchange by a first heat exchanger 5 before entering a hydrogenation reactor to reach the inlet temperature of a catalyst bed layer of the hydrogenation reactor, and then enter the hydrogenation reactor for hydrogenation reaction.

In a preferred embodiment, the system further comprises a second heat exchanger 8;

the hydrogenation reactor 1 is communicated with the first gas-liquid separator 21 through the first heat exchanger 5 and the second heat exchanger 8 in sequence, and is used for performing first gas-liquid separation on a crude ethanol mixture obtained by catalytic reaction after first heat exchange and second heat exchange in sequence.

The crude ethanol mixture obtained from the hydrogenation reactor 1 is subjected to heat exchange by a first heat exchanger 5, enters a second heat exchanger 8 such as a water cooler and is further cooled to 30-50 ℃, and then enters a first gas-liquid separator 21 for first gas-liquid separation.

In a preferred embodiment, the system further comprises a heater 9;

the first heat exchanger 5 is communicated with the hydrogenation reactor 1 through the heater 9, and is used for heating the material obtained by the first heat exchange and then carrying out catalytic reaction.

Before entering a hydrogenation reactor, a hydrogenation reaction raw material gas passes through a first heat exchanger 5 and a heater 9 to reach the inlet temperature of a catalyst bed layer of the hydrogenation reactor, and then enters the hydrogenation reactor for hydrogenation reaction. In the initial stage of start-up, the temperature cannot meet the reaction requirement, the hydrogenation reaction raw material enters a heater 9 for preheating, and enters a catalyst bed layer for hydrogenation reaction after the preheating reaches the inlet temperature of the catalyst bed layer; in the initial start-up stage, the heater 9 provides a unique heat source for the hydrogenation reaction in the hydrogenation reactor; the heat source of the heater 9 may be low pressure steam.

In a preferred embodiment, as shown in fig. 2, the system further comprises an ethylene glycol separation unit 10;

the light component separation tower 3 is communicated with the ethylene glycol separation device 10 and is used for separating freezing-grade ethylene glycol, obtaining light components from the top of the tower, obtaining polyester-grade ethylene glycol from the lateral line of the tower body and obtaining heavy components from the bottom of the tower. The polyester grade glycol is present in a higher concentration than the refrigeration grade glycol, e.g., in a concentration of 99.99 wt.%.

Introducing the refrigeration-grade ethylene glycol obtained from the light component separation tower into an ethylene glycol separation device 10, obtaining light components from the tower top, and enabling the light components to enter an outdoor recovery processing device for further recovery processing; heavy components are obtained from the tower bottom and can enter an outside recovery processing device for subsequent processing; polyester grade ethylene glycol was obtained from the shaft side.

In a preferred embodiment, the number of theoretical plates of the ethylene glycol separation device 10 is 30-100, the temperature at the top of the tower is 100-150 ℃, the temperature at the bottom of the tower is 130-230 ℃, and the absolute pressure at the top of the tower is 5-50 KPa; the reflux ratio of light components at the top of the ethylene glycol separation device 10 is 50-120 or total reflux.

The ethylene glycol separation device 10 may be a packed column, a tray column, or a bubble column. When the ethylene glycol separation device 10 is a packed tower, the packing filled in the packed tower is random packing or high-efficiency regular packing. The random packing is in the shape of saddle, Raschig ring, pall ring, wheel, intalox saddle ring, sphere or column. The efficient structured packing is corrugated packing, grid packing or pulse packing.

In a preferred embodiment, as shown in fig. 3, the system further comprises a three-phase azeotropic distillation column 11;

the light component separation tower 3 is communicated with the three-phase azeotropic distillation tower 11 and is used for carrying out three-phase azeotropic distillation on common ethanol and an entrainer to obtain anhydrous ethanol and light components mainly comprising water. By adopting the technical scheme, the absolute ethyl alcohol and the freezing-grade ethylene glycol or the absolute ethyl alcohol and the polyester-grade ethylene glycol can be obtained. The concentration of the absolute ethyl alcohol is higher than that of the common ethyl alcohol, such as the concentration is more than or equal to 99.5 wt%.

The common ethanol and the entrainer from the light component separation tower 3 enter a three-phase azeotropic rectifying tower 11, an anhydrous ethanol product is extracted from the bottom of the tower after separation, and the light component mainly comprising water is obtained from the top of the tower.

The three-phase azeotropic distillation column 11 may be a packed column, a plate column or a bubble column. When the three-phase azeotropic distillation tower 11 is a packed tower, the packing filled in the packed tower can be random packing or high-efficiency regular packing. The random packing is in a saddle shape, a Raschig ring, a pall ring, a wheel shape, a rectangular saddle ring, a spherical shape or a columnar shape; the efficient structured packing is corrugated packing, grid packing or pulse packing.

In a preferred embodiment, the number of theoretical plates of the three-phase azeotropic distillation tower 11 is 9-50, the pressure at the top of the tower is 0.5-1.8 MPa, and the temperature at the bottom of the tower is 100-300 ℃.

In a preferred embodiment, the light phase reflux ratio of the three-phase azeotropic distillation column 11 is 0.01 to 3.0.

In a preferred embodiment, the heavy phase reflux ratio of the three-phase azeotropic distillation tower 11 is 0.01 to 3.0.

In a preferred embodiment, the complementary entrainer of the three-phase azeotropic distillation column 11 is selected from at least one of cyclohexane and benzene, more preferably cyclohexane.

In a preferred embodiment, the three-phase azeotropic distillation column 11 comprises a distillation column body 111, an overhead condenser 112, a kettle reboiler 113, and a multiphase separator 114;

the rectifying tower body 111 is provided with an entrainer inlet 1111, a tower top outlet 1112 and a tower bottom outlet 1113; the multiphase separator 114 is provided with a light phase outlet 1141 and a heavy phase outlet 1142;

the overhead outlet 1112 is in communication with the multiphase separator 114 via the overhead condenser 112; the light phase outlet 1141 is divided into two paths: one path is refluxed to the rectifying tower body 111, and the other path is communicated with the entrainer inlet 1111; the heavy phase outlet 1142 is divided into two paths: one path is refluxed to the rectifying column body 111, and the other path obtains a light component mainly composed of water.

The tower bottom outlet 1113 is divided into two paths: one passage is communicated with the rectifying tower body 111 through the tower kettle reboiler 113, and the other passage obtains the absolute ethyl alcohol. The material obtained from the top outlet 1112 of the rectifying column body 111 is introduced into the multiphase separator 114 through the top condenser 112, a part of the light phase obtained from the light phase outlet 1141 flows back to the rectifying column body 111, a part of the light phase is introduced into the rectifying column body 111 through the entrainer inlet 1111, a part of the heavy phase obtained from the heavy phase outlet 1142 flows back to the rectifying column body 111, and a part of the heavy phase is a light component mainly comprising water.

In a preferred embodiment, as shown in FIG. 4, the system further comprises a wastewater tower 12;

the three-phase azeotropic distillation tower 11 is communicated with the waste water tower 12 and is used for separating light components mainly comprising water, obtaining an alcohol-water mixture from the top of the tower and obtaining treated water from the bottom of the tower.

The light component which is obtained from the three-phase azeotropic rectifying tower 11 and mainly comprises water enters a waste water tower 12, an alcohol-water mixture is obtained from the tower top, the light component at the tower top can be circulated to the three-phase azeotropic rectifying tower 11 to recycle ethanol, and the treated water is obtained from the tower bottom and can be discharged to the outside as greening water.

The wastewater tower can be a packed tower, a plate tower or a bubble cap tower. When the waste water tower is a packed tower, the packed packing is random packing or efficient regular packing. The random packing is in the shape of saddle, Raschig ring, pall ring, wheel, intalox saddle ring, sphere or column. The efficient structured packing is corrugated packing, grid packing or pulse packing.

In a preferred embodiment, the number of theoretical plates of the wastewater tower is 5-30, the temperature at the top of the tower is 58-130 ℃, the temperature at the bottom of the tower is 70-260 ℃, and the absolute pressure at the top of the tower is 50-350 KPa.

In a preferred embodiment, the reflux ratio of the wastewater tower is 1-5.

In a preferred embodiment, the wastewater tower 12 is in communication with the three-phase azeotropic distillation tower 11 for refluxing the alcohol-water mixture to the three-phase azeotropic distillation tower 11 for three-phase azeotropic distillation.

The utility model discloses during the system of oxalate production ethanol used, carry out catalytic reaction with hydrogen and industrial grade oxalate earlier and synthesize crude ethanol mixture in hydrogenation ware 1, crude ethanol mixture separates in methanol separation device 2 and obtains the mixture that uses methanol as the main and the mixture that contains ethanol and ethylene glycol, and the mixture that contains ethanol and ethylene glycol separates in light component knockout tower 3 and obtains ordinary ethanol and freezing grade ethylene glycol. Further, the freezing-grade ethylene glycol is separated in the ethylene glycol separation device 10, light components are obtained from the top of the tower, polyester-grade ethylene glycol is obtained from the side line of the tower body, and heavy components are obtained from the bottom of the tower. Further, the common ethanol and the entrainer are subjected to three-phase azeotropic distillation in a three-phase azeotropic distillation tower 11 to obtain anhydrous ethanol and a light component which mainly comprises water. Still further, the light components mainly consisting of water are separated in the wastewater column 12, and an alcohol-water mixture is obtained from the top of the column and treated water is obtained from the bottom of the column.

Example 1

In this embodiment, each reaction module is arranged in the system for producing ethanol from oxalate shown in fig. 2, and industrial grade ethanol and polyester grade ethylene glycol are produced.

A hydrogenation reactor 1 (a plate type fixed bed hydrogenation reactor, the inner diameter is 325mm, the height is 900mm) is provided with a plate group fixing cavity in the center, three groups of plates are arranged in the plate group fixing cavity, and each group comprises 3 plates; a catalyst bed layer is arranged between the outer wall of the plate group fixing cavity and the inner wall of the hydrogenation reactor, and is filled with a hydrogenation reaction catalyst: the catalyst is sold in Shanghai Peng engineering technology Co., Ltd, and the trade name of the catalyst is MEG-803T).

Technical grade H₂(the purity is 99.9 v%) and recycle gas from the first gas-liquid separator 5 (the composition is that hydrogen is 96 v%, methane is 0.05 v%, nitrogen is 0.02 v%, carbon monoxide is 0.02 v%, methanol is 3 v%, other 0.91 v%) are compressed by the compressor 4, then are converged with dimethyl oxalate (99.9% wt) from a border zone carbonylation device, enter the first heat exchanger 5 to be preheated to 175 ℃, firstly enter from the top of the hydrogenation reactor 1, and then enter the catalyst bed layer in a radial flow mode to carry out hydrogenation reaction (the hotspot temperature of the catalyst bed layer is 190 ℃, the reaction pressure is 3.0MPa, and the liquid hourly space velocity is 2.8 Kg/Kg.h); the hydrogenated product is discharged from the bottom, enters a first heat exchanger 5 and a second heat exchanger 8 for heat exchange to 30-50 ℃, and then enters a first gas-liquid separator 5 for gas-liquid separation.

At the initial stage of start-up, the material passing through the first heat exchanger 5 enters the heater 9 for preheating, and the preheated gas serving as the feed gas enters the catalyst bed layer for hydrogenation after reaching the inlet temperature of the catalyst bed layer.

After the hydrogenation product is separated by the first gas-liquid separator 5, most of the gas phase enters the compressor 4 as the recycle gas, the rest non-condensable gas (gas content: 1.2 v%) enters the second gas-liquid separator 22 after decompression and temperature reduction, and the liquid phase (methanol: 50.1 wt%, ethylene glycol: 48.55 wt%, methyl glycolate: 0.06 wt%, ethanol: 0.39 wt%, BDO:0.12 wt%, and the rest 0.78 wt%) discharged from the first gas-liquid separator 5 enters the methanol recovery tower 23 for separation. The liquid phase separated by the second gas-liquid separator 22 enters a methanol recovery tower 23 for separation, after methanol is further removed from the gas phase by a flash tank 24 (the inner diameter is 160mm, the height is 900mm), most of the gas phase (the components are 97 v% of hydrogen, 0.15 v% of methane, 0.06 v% of nitrogen, 0.27 v% of carbon monoxide and the other 2.52 v%) enters a compressor 4 for recycling through pressurization and temperature reduction, and only a small part of non-condensable gas is discharged outside as purge gas for recycling.

In a methanol recovery tower 23 (the inner diameter is 50mm, the height is 3600mm, the number of theoretical plates is 25, efficient structured packing is filled in the tower, the temperature of the tower top is 50.82 ℃, the temperature of a tower kettle is 171 ℃, and the absolute pressure of the tower top is 90kPa), materials are fed at a 12 th tower plate, non-condensable gas at the tower top enters a flash tank 24 for treatment and then enters a compressor 4, the reflux ratio of the tower top is 1.6, and discharged materials at the tower top (99.9 wt% of methanol and 0.1 wt% of other low boiling point components) are extracted and used as raw materials of a carbonylation device outside a boundary region; heavy components (composition: 96 wt% of ethylene glycol, 0.12 wt% of methyl glycolate, 2.68 wt% of 1.2-BDO, 0.8 wt% of ethanol, 0.4 wt% of other components) in the bottom of the methanol recovery tower 23 enter a light component separation tower 3.

The light component separation tower 3 (the inner diameter: 50mm, the height: 5800mm, the number of theoretical plates: 40, the high-efficiency structured packing filled in, the tower top temperature 83.8 ℃, the tower bottom temperature 146.9 ℃, the absolute pressure at the tower top 16kPa, the reflux ratio at the tower top 50), the heavy components at the tower bottom (97.9 wt% of glycol, 2.1 wt% of 1.2-BDO) enter the glycol separation device 10 for further separation. The common ethanol product (98 wt% ethanol, 2 wt% methyl glycolate) is led out from the tower top and sent to a storage tank for storage.

In an ethylene glycol separation device 10 (the inner diameter is 50mm, the height is 8600mm, the number of theoretical plates of a tower is 60, high-efficiency structured packing is filled in the device, the temperature of the top of the tower is 130 ℃, the temperature of a bottom of the tower is 170.1 ℃, and the absolute pressure of the top of the tower is 5kPa), the reflux ratio of the top of the tower is 98, the components of 1, 2-BDO (19.79 wt percent, 80wt percent of ethylene glycol and 0.21wt percent of the other components) are extracted from the top of the tower to the outside of a battery limits and recovered as a byproduct, the condensation polymer containing a small amount of ethylene glycol and ethylene glycol is treated outside the battery limits in the bottom of the tower, and the polyester-grade ethylene glycol (the content is 99.99wt percent) which is the final product is extracted from the 5 th tower plate on the side line of a tower body of the ethylene glycol separation device 10.

Example 2

In this example, each reaction module was set up to produce anhydrous ethanol and refrigeration grade ethylene glycol with reference to the system for producing ethanol from oxalate shown in fig. 3.

Technical grade H₂(the purity is 99.9 v%) and recycle gas (the composition is 98.90 v% of hydrogen, 0.04 v% of ethanol, 0.15 v% of methanol and 0.91 v% of the others) from a first gas-liquid separator 5 are compressed by a compressor 4, then are converged with dimethyl oxalate (99.9 wt%) from a border zone outer carbonylation device, enter a first heat exchanger 5, are preheated to 220 ℃, firstly enter from the top of a hydrogenation reactor 1, and then enter a catalyst bed layer in a radial flow mode to carry out hydrogenation reaction (the hot spot temperature of the catalyst bed layer is 235 ℃, the reaction pressure is 6.0MPa, and the liquid hourly space velocity is 1.0 Kg/Kg.h); the hydrogenated product is discharged from the bottom, enters a first heat exchanger 5 and a second heat exchanger 8 for heat exchange to 30-50 ℃, and then enters a first gas-liquid separator 5 for gas-liquid separation.

After the hydrogenation product is separated by the first gas-liquid separator 5, most of the gas phase enters the compressor 4 as the recycle gas, the rest non-condensable gas (gas content: 1.2 v%) enters the second gas-liquid separator 22 after decompression and temperature reduction, and the liquid phase (methanol: 50.01 wt%, ethylene glycol: 0.05 wt%, ethanol: 35.9 wt%, water: 14.03 wt%, BDO:0.0014 wt%, 1, 2-propylene glycol: 0.0012 wt%, and the rest 0.00735 wt%) discharged from the first gas-liquid separator 5 enters the methanol recovery tower 23 for separation. The liquid phase separated by the second gas-liquid separator 22 enters a methanol recovery tower 23 for separation, after methanol is further removed from the gas phase by a flash tank 24 (the inner diameter is 160mm, the height is 900mm), most of the gas phase (the components are 99.65 v% of hydrogen, 0.08 v% of ethanol, 0.25 v% of methanol and 0.01 v% of water) enters a compressor 4 for recycling through pressurization and temperature reduction, and only a small part of non-condensable gas is discharged outside as purge gas for recycling.

In a methanol recovery tower 23 (the inner diameter is 50mm, the height is 7800mm, the number of theoretical plates is 53, efficient structured packing is filled in the tower, the temperature of the tower top is 21.50 ℃, the temperature of a tower kettle is 85.29 ℃, and the absolute pressure of the tower top is 105kPa), materials are fed at a tower plate 22, tower top non-condensable gas (comprising hydrogen 82.11 v%, methanol 17.87 v% and other 0.02 v%) enters a flash tank 24 for treatment and then enters a compressor 4, the reflux ratio of the tower top is 1.6, and tower top discharged materials (99.83 wt% of methanol, 0.07 wt% of ethanol and 0.1 wt% of other low boiling point components) are extracted and used as raw materials of a carbonylation device outside a boundary zone; heavy components (the composition: 0.09 wt% of ethylene glycol, 28.12 wt% of water, 71.77 wt% of ethanol and 0.02 wt% of other components) in the bottom of the methanol recovery tower 23 enter a light component separation tower 3.

A light component separation tower 3 (the inner diameter is 50mm, the height is 1000mm, the number of theoretical plates is 7, efficient structured packing is filled in the tower, the temperature of the top of the tower is 83.09 ℃, the temperature of a tower kettle is 116.7 ℃, the absolute pressure of the top of the tower is 105kPa, the reflux ratio of the top of the tower is 1), and an ethanol crude product (71.88 wt% ethanol and 28.11 wt% water) is led out from the top of the tower and enters a three-phase azeotropic distillation tower 11; freezing-grade ethylene glycol is prepared from heavy components in the tower bottom (58.91 wt% of ethylene glycol, 37.83 wt% of water, 1.37 wt% of 1, 2-propylene glycol, 1.78 wt% of 1, 2-BDO, 0.1 wt% of others).

In a three-phase azeotropic distillation tower 11 (with an inner diameter of 50mm, a height of 8900mm, a theoretical plate number of the tower of 62, a high-efficiency structured packing filled therein, a tower top temperature of 72.35 ℃, a tower bottom temperature of 81.5 ℃ and an absolute pressure of a tower top of 105kPa), the feed composition is that a supplementary entrainer (the component: cyclohexane is 100 wt%) enters from a tower plate 1, an alcohol-water mixture (the component: 71.88 wt% ethanol, 28.11 wt% water) enters from a tower plate 20, a light phase at the tower top (the component: ethanol is 32.39 wt%, water is 0.38 wt%, methanol is 0.04 wt%, cyclohexane is 67.2 wt%) circulates to a supplementary entrainer inlet 1111, a light phase reflux ratio is 1, a heavy phase at the tower top (the component: ethanol is 64.45 wt%, water is 35.34 wt%, and the other 0.21 wt%) enters a waste water tower 12, and a heavy phase reflux ratio is 3.5. The bottom of the tower is the final product absolute ethyl alcohol (the content is 99.91 wt%).

In a waste water tower 12 (the inner diameter is 50mm, the height is 1500mm, the number of theoretical plates of the tower is 10, high-efficiency structured packing is filled in the waste water tower, the temperature of the top of the tower is 72.95 ℃, the temperature of a bottom of the tower is 103.6 ℃, and the absolute pressure of the top of the tower is 105kPa), a recovered alcohol-water mixture (the components comprise 0.26 wt% of methanol, 88.58 wt% of ethanol, 11.14 wt% of water and 0.02 wt% of the rest) is circulated to the 20 th tower plate of an alcohol-water mixture inlet of a three-phase azeotropic distillation tower 11, and a material flow discharged from the bottom of the tower (the components comprise 99.99 wt% of water and 0.01 wt% of the rest) can be discharged to the outside of a boundary area as greening water after being subjected to fine cooling treatment.

Example 3

In this example, the reaction components are arranged in the system for producing ethanol from oxalate shown in fig. 4, and anhydrous ethanol and polyester-grade ethylene glycol are produced.

Technical grade H₂(purity: 99.9 v%) and a recycle gas (composition: hydrogen 99.87 v%, ethanol 0.02 v%, methanol 0.10 v%, others 0.01 v%) from the first gas-liquid separator 5 were passed through a compressor4 after compression, the mixture is merged with dimethyl oxalate (99.9 percent by weight) from a border zone outer carbonylation device, enters a first heat exchanger 5, is preheated to 195 ℃, firstly enters from the top of a hydrogenation reactor 1, and then enters a catalyst bed layer in a radial flow mode to carry out hydrogenation reaction (the hotspot temperature of the catalyst bed layer is 210 ℃, the reaction pressure is 5.0MPa, and the liquid hourly space velocity is 1.0 Kg/Kg.h); the hydrogenated product is discharged from the bottom, enters a first heat exchanger 5 and a second heat exchanger 8 for heat exchange to 30-50 ℃, and then enters a first gas-liquid separator 5 for gas-liquid separation.

After the hydrogenation product is separated by the first gas-liquid separator 5, most of the gas phase enters the compressor 4 as the recycle gas, the rest non-condensable gas (gas content: 1.2 v%) enters the second gas-liquid separator 22 after decompression and temperature reduction, and the liquid phase (methanol: 48.3 wt%, ethylene glycol: 24.74 wt%, ethanol: 18.02 wt%, BDO:0.75 wt%, water: 7.56 wt%, 1, 2-propylene glycol: 0.62 wt%) discharged from the first gas-liquid separator 5 enters the methanol recovery tower 23 for separation. The liquid phase (methanol: 69.55 wt%, ethylene glycol: 0.2 wt%, ethanol: 23.13 wt%, water: 7.09 wt%, 1, 2-propylene glycol: 0.01 wt%, and others: 0.02 wt%) separated by the second gas-liquid separator 22 enters a methanol recovery tower 23 for separation, the gas phase is further subjected to methanol removal by a flash tank 24 (inner diameter 160mm, height 900mm), wherein most of the gas phase (composition: hydrogen 99.62 v%, ethanol 0.05 v%, methanol 0.30 v%, and others 0.03 v%) is subjected to pressure increase and temperature reduction and enters a compressor 4 for recycling, and only a small part of non-condensable gas is discharged outside as purge gas for recycling.

In a methanol recovery tower 23 (the inner diameter is 50mm, the height is 7500mm, the number of theoretical plates is 52, efficient structured packing is filled in, the temperature of the tower top is 21.5 ℃, the temperature of a tower kettle is 97.32 ℃, and the absolute pressure of the tower top is 105kPa), materials are fed at a tower plate 22, tower top non-condensable gas (comprising hydrogen gas 86.50 v% and methanol 13.50 v%) enters a flash tank 24 for treatment and then enters a compressor 4, the reflux ratio of the tower top is 6, and the discharged materials (99.9 wt% of methanol, 0.09 wt% of ethanol and other 0.01 wt%) at the tower top are taken out and used as raw materials of a carbonylation device outside a boundary zone; heavy components (composition: 45.86 wt% of ethylene glycol, 1.39 wt% of 1.2-BDO, 36.78 wt% of ethanol, 14.8 wt% of water, 1.15 wt% of 1, 2-propylene glycol and 0.02 wt% of the rest) in the bottom of the methanol recovery tower 23 enter a light component separation tower 3.

A light component separation tower 3 (the inner diameter: 50mm, the height is 1000mm, the number of theoretical plates is 7, efficient structured packing is filled in the tower, the temperature of the tower top is 83.1 ℃, the temperature of the tower bottom is 204.5 ℃, the absolute pressure of the tower top is 105kPa, the reflux ratio of the tower top is 1), a crude ethylene glycol product (88.03 wt% ethylene glycol, 1.2-BDO 2.66 wt%, 1, 2-propanetriol 2.22 wt%, and the other 7.1 wt%) is introduced into the tower bottom and enters an ethylene glycol separation device 10 for further separation, and a crude ethanol product (71.29 wt% ethanol, water 28.69 wt%, and methanol 0.01 wt%) is introduced from the tower top and enters a three-phase azeotropic distillation tower 11.

In a three-phase azeotropic distillation tower 11 (with an inner diameter of 50mm, a height of 8900mm, a theoretical plate number of the tower of 62, a high-efficiency structured packing filled therein, a tower top temperature of 72.35 ℃, a tower bottom temperature of 81.5 ℃ and an absolute pressure of a tower top of 105kPa), the feed composition is that a supplementary entrainer (the component: cyclohexane is 100 wt%) enters from a tower plate 1, an alcohol-water mixture (the component: 71.29 wt% ethanol and 28.69 wt% water) enters from a tower plate 20, a light phase (the component: ethanol is 38.52 wt%, water is 0.52 wt%, methanol is 0.04 wt%, and cyclohexane is 60.92 wt%) is extracted from the tower top, and circulates to a supplementary entrainer inlet 1111, the reflux ratio of the light phase is 1, and the reflux ratio of the heavy phase (the component: ethanol is 71.64 wt%, water is 28.09 wt%, and the other 0.27 wt%) is extracted from the tower top of the waste water tower into a waste water tower 12, and the reflux ratio of the heavy phase is 3.5. The bottom of the tower is the final product absolute ethyl alcohol (the content is 99.91 wt%).

In a waste water tower 12 (the inner diameter is 50mm, the height is 1500mm, the number of theoretical plates of the tower is 10, high-efficiency structured packing is filled in the waste water tower, the temperature of the top of the tower is 79.18 ℃, the temperature of a bottom of the tower is 103.6 ℃, and the absolute pressure of the top of the tower is 105kPa), a recovered alcohol-water mixture (the components comprise 0.22 wt% of methanol, 88.91 wt% of ethanol, 10.76 wt% of water and 0.12 wt% of the rest) is circulated to the 20 th tower plate of an alcohol-water mixture inlet of a three-phase azeotropic distillation tower 11, and a material flow discharged from the bottom of the tower (the components comprise 99.99 wt% of water and 0.01 wt% of the rest) can be discharged to the outside of a battery limits as greening water after being cooled.

In an ethylene glycol separation device 10 (the inner diameter is 50mm, the height is 5500mm, the theoretical plate number of a tower is 35, high-efficiency structured packing is filled in the device, the temperature of the top of the tower is 114 ℃, the temperature of a tower bottom of the tower is 119 ℃, and the absolute pressure of the top of the tower is 5kPa), the reflux ratio of the top of the tower is 50, the components (1, 2-BDO is 19.79wt percent, the ethylene glycol is 80wt percent, and the other components are 0.21wt percent) are extracted from the top of the tower to the outside of a battery limits and are recovered as a byproduct, the condensation polymer containing a small amount of ethylene glycol and ethylene glycol is treated outside the battery limits in the tower bottom of the tower, and the final product polyester-grade ethylene glycol (the content is 99.99wt percent) is extracted from the 9 th tower plate on the side line of a tower body of the ethylene glycol separation device 10.

The above embodiments are merely illustrative of the principles and effects of the present invention, and are not to be construed as limiting the invention. Modifications and variations can be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A system for producing ethanol from oxalate, comprising:

a hydrogenation reactor (1);

the methanol separation device (2), the methanol separation device (2) is communicated with the hydrogenation reactor (1);

a light component separation column (3);

the light component separation tower (3) is communicated with the methanol separation device (2).

2. The system for producing ethanol from oxalate according to claim 1, wherein,

the methanol separation device (2) comprises:

a first gas-liquid separator (21); the first gas-liquid separator (21) is communicated with the hydrogenation reactor (1);

a second gas-liquid separator (22); the second gas-liquid separator (22) is in communication with the first gas-liquid separator (21);

a methanol recovery column (23); the methanol recovery column (23) is in communication with the first gas-liquid separator (21) and the second gas-liquid separator (22);

the hydrogenation reactor (1) is a plate reactor, a tubular reactor or a tubular/plate composite reactor.

3. The system for producing ethanol from oxalate according to claim 2, wherein,

the methanol separation device (2) further comprises a flash tank (24);

the flash tank (24) is communicated with the second gas-liquid separator (22) and is used for flashing a second gas phase obtained by second gas-liquid separation;

the methanol recovery tower (23) is communicated with the flash tank (24) and is used for carrying out flash evaporation on the non-condensable gas obtained by methanol recovery;

the flash tank (24) is communicated with the methanol recovery tower (23) and is used for recovering methanol from the liquid phase obtained by flash evaporation;

the hydrogenation reactor (1) is a plate-type fixed bed reactor, a plate group fixing cavity is arranged in the center of the hydrogenation reactor (1), and a plate group is arranged in the plate group fixing cavity; and a catalyst bed layer is arranged between the outer wall of the plate group fixing cavity and the inner wall of the hydrogenation reactor (1).

4. A system for producing ethanol from oxalate according to claim 3, wherein the system further comprises a compressor (4) and a first heat exchanger (5);

the first gas-liquid separator (21) is communicated with the hydrogenation reactor (1) through the compressor (4) and the first heat exchanger (5) in sequence, and is used for circulating a part of first gas phase obtained by separating the first gas and the liquid to the hydrogenation reactor (1) as a catalytic reaction raw material after compression and heat exchange in sequence;

the flash tank (24) is communicated with the hydrogenation reactor (1) through the compressor (4) and the first heat exchanger (5) in sequence, and is used for circulating a part of flash vapor phase obtained by flash evaporation to the hydrogenation reactor (1) as a catalytic reaction raw material after compression and heat exchange in sequence.

5. The system for producing ethanol from oxalate according to claim 4, wherein,

the flash tank (24) is provided with a non-condensable gas discharge pipeline (241) for discharging non-condensable gas;

the system further comprises a hydrogen feed line (6) and an oxalate feed line (7);

the hydrogen raw material pipeline (6) is communicated with the hydrogenation reactor (1) through the compressor (4) and the first heat exchanger (5) in sequence, and is used for introducing the hydrogen raw material into the hydrogenation reactor (1) after compression and heat exchange in sequence;

the oxalate raw material pipeline (7) is communicated with the hydrogenation reactor (1) through the first heat exchanger (5) and is used for introducing an oxalate raw material into the hydrogenation reactor (1) after heat exchange;

the system further comprises a second heat exchanger (8);

the hydrogenation reactor (1) is communicated with the first gas-liquid separator (21) through the first heat exchanger (5) and the second heat exchanger (8) in sequence, and is used for performing first gas-liquid separation on a crude ethanol mixture obtained by catalytic reaction after first heat exchange and second heat exchange in sequence;

the system further comprises a heater (9);

the first heat exchanger (5) is communicated with the hydrogenation reactor (1) through the heater (9) and is used for heating the material obtained by the first heat exchange and then carrying out catalytic reaction.

6. A system for producing ethanol from oxalate according to claim 1, wherein the system further comprises a glycol separation device (10);

the light component separation tower (3) is communicated with the ethylene glycol separation device (10).

7. A system for producing ethanol from oxalate according to claim 1 or 6, wherein the system further comprises a three-phase azeotropic distillation column (11);

the light component separation tower (3) is communicated with the three-phase azeotropic distillation tower (11).

8. The system for producing ethanol from oxalate according to claim 7, wherein the three-phase azeotropic distillation column (11) comprises a distillation column body (111), an overhead condenser (112), a kettle reboiler (113) and a multiphase separator (114);

the rectifying tower body (111) is provided with an entrainer inlet (1111), a tower top outlet (1112) and a tower bottom outlet (1113); the multiphase separator (114) is provided with a light phase outlet (1141) and a heavy phase outlet (1142);

the overhead outlet (1112) is in communication with the multiphase separator (114) via the overhead condenser (112); the light phase outlet (1141) is divided into two paths: one path is refluxed to the rectifying tower body (111), and the other path is communicated with the entrainer inlet (1111); the heavy phase outlet (1142) is divided into two paths: one path is refluxed to the rectifying tower body (111), and the other path obtains light components mainly comprising water;

the bottom outlet (1113) is divided into two paths: one passage is communicated with the rectifying tower body (111) through the tower kettle reboiler (113), and the other passage obtains the absolute ethyl alcohol.

9. A system for producing ethanol from oxalate according to claim 7, characterized in that the system further comprises a waste water tower (12);

the three-phase azeotropic distillation tower (11) is communicated with the waste water tower (12).

10. The system for producing ethanol from oxalate according to claim 9, wherein the waste water tower (12) is in communication with the three-phase azeotropic distillation tower (11).