A dimethyl oxalate rectification device for coal chemical industry

Abstract

The present invention discloses a rectification device for dimethyl oxalate in coal chemical industry. The device includes a dimethyl oxalate light component removal device and a dimethyl carbonate separation device. The dimethyl oxalate light component removal device mainly includes a dimethyl oxalate light component removal tower, a reboiler for the light component removal tower, an inlet and outlet heat exchanger, a feed tank for the light component removal tower, a top condenser for the light component removal tower, etc.; the dimethyl carbonate separation device mainly includes a dimethyl carbonate separation tower, a reboiler for the dimethyl carbonate separation tower, a top condenser for the dimethyl carbonate separation tower, a vent condenser, a reflux drum for the dimethyl carbonate separation tower, a reflux pump for the dimethyl carbonate separation tower, a cooler for dimethyl carbonate, etc. The present invention not only purifies crude dimethyl oxalate, but also separates methanol and dimethyl carbonate in the crude dimethyl oxalate mixture without introducing other boiling point depressants. The high-purity dimethyl oxalate is applied to the downstream industrialization industry of dimethyl oxalate, the separated methanol is reused, and the separated crude dimethyl carbonate is sent to a subsequent device for purification treatment.

Description

Technical Field

[0001] The invention belongs to the field of dimethyl oxalate distillation, in particular to a coal chemical dimethyl oxalate distillation device. Background Art

[0002] Ethylene glycol is an important chemical raw material, mainly used as a raw material for solvents, antifreeze and synthetic polyester resins. At present, ethylene glycol is mainly prepared by direct hydration of ethylene oxide. Since the preparation of ethylene oxide uses ethylene as raw material, large-scale production mainly depends on petroleum resources. However, my country's overall energy characteristics are rich in coal, gas and less oil. Therefore, it is of great significance to efficiently convert coal into chemical raw materials such as ethylene glycol and reduce the dependence of chemical raw materials on petroleum resources, which is conducive to optimizing the energy and resource structure.

[0003] In recent years, with the gradual maturity of coal-to-ethylene glycol technology, a large number of coal-to-ethylene glycol enterprises have been built in China. According to reliable statistics, in the next few years, my country's coal-to-ethylene glycol production capacity will reach more than 8 million tons. Dimethyl oxalate is an intermediate product in the production process of coal-to-ethylene glycol. It is prepared by carbonylation synthesis reaction. The carbonylation synthesis unit has a complex reaction. The main target product is dimethyl oxalate, which also has a series of side reactions. The products include dimethyl carbonate, methyl formate, methyl acetate, methyl formate and heavy components with a boiling point higher than dimethyl oxalate. The impurity components in the product are numerous and complex, which has a great negative impact on the subsequent hydrogenation process catalyst, resulting in high catalyst bed resistance and short life. Therefore, in order to ensure the effective operation time of the hydrogenation catalyst and reduce production costs, the dimethyl oxalate product must be refined to obtain a high-purity target product. The current processing devices basically adopt conventional atmospheric distillation, pressure distillation or extractive distillation devices. The patent (publication number CN104098441A) provides a process and device system for producing dimethyl oxalate by high-pressure carbonylation of industrial synthesis gas and hydrogenating it to produce ethylene glycol. The patent (publication number CN110003007A) provides a distillation and purification system and method for synthesizing dimethyl oxalate by carbonylation of coal-based ethylene glycol. The patent (publication number CN102898305A) dimethyl oxalate distillation equipment, the patent (publication number CN210314061U) provides a distillation and purification device for synthesizing dimethyl oxalate by carbonylation of coal-based ethylene glycol, and the patent (publication number CN203890271U) provides a device system for producing ethylene glycol from industrial synthesis gas and co-producing dimethyl carbonate. The distillation of dimethyl oxalate involved in the process of the above public patents does not involve the separation of methanol and dimethyl carbonate in crude dimethyl oxalate during the distillation and purification of dimethyl oxalate. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides a rectification device for dimethyl oxalate in coal chemical industry. This device can not only rectify and purify crude dimethyl oxalate, but also rectify and separate methanol and dimethyl carbonate in crude dimethyl oxalate.

[0005] A rectification device for dimethyl oxalate in coal chemical industry includes a dimethyl oxalate light component removal device and a dimethyl carbonate separation device;

[0006] The dimethyl oxalate light component removal device includes a dimethyl oxalate light component removal tower, a reboiler for the light component removal tower, an inlet-outlet heat exchanger, a feed tank for the light component removal tower, a top condenser for the light component removal tower, a reflux drum for the light component removal tower, a reflux pump for the light component removal tower, and a bottom pump for the light component removal tower. The tube-side inlet and the tube-side outlet of the inlet-outlet heat exchanger are respectively connected to a crude dimethyl oxalate storage tank and the inlet of the feed tank for the light component removal tower through pipelines. The liquid-phase outlet and the gas-phase outlet of the feed tank for the light component removal tower are respectively connected to the gas-phase feed inlet and the liquid-phase feed inlet in the middle of the dimethyl oxalate light component removal tower through pipelines. The bottom liquid outlet of the dimethyl oxalate light component removal tower is connected to the feed inlet of the dimethyl carbonate separation tower through the bottom pump for the light component removal tower. A reflux pipeline a communicating with the bottom of the dimethyl oxalate light component removal tower is arranged on the pipeline connecting the outlet of the bottom pump for the light component removal tower and the feed inlet of the dimethyl carbonate separation tower. The bottom liquid inlet of the reboiler for the light component removal tower and the gas-phase outlet of the reboiler for the light component removal tower are respectively communicated with the bottom of the dimethyl oxalate light component removal tower and the side of the bottom of the dimethyl oxalate light component removal tower through pipelines. The top gas-phase outlet of the dimethyl oxalate light component removal tower is connected to the gas-phase inlet of the top condenser for the light component removal tower through a pipeline. The gas-phase outlet of the top condenser for the light component removal tower is connected to the inlet of a compressor. The condensate outlet of the top condenser for the light component removal tower is connected to the inlet of the reflux drum for the light component removal tower through a pipeline. The outlet of the reflux drum for the light component removal tower is connected to the inlet of the reflux pump for the light component removal tower through a pipeline. The outlet of the reflux pump for the light component removal tower is connected to a methyl formate separation device through a pipeline. A reflux pipeline b connecting to the top of the dimethyl oxalate light component removal tower is arranged on the pipeline connecting the outlet of the reflux pump for the light component removal tower and the feed inlet of the methyl formate separation tower;

[0007] The dimethyl carbonate separation device includes a dimethyl carbonate separation column, a dimethyl carbonate separation column reboiler, a dimethyl carbonate top condenser, a vent condenser, a dimethyl carbonate separation column reflux drum, a dimethyl carbonate separation column reflux pump, a dimethyl carbonate cooler, a refined dimethyl oxalate pump, a heavy component pump, a hot water cooler, a refined dimethyl oxalate reflux cooler. The gas phase outlet at the top of the dimethyl carbonate separation column is connected to the gas phase inlet of the dimethyl carbonate top condenser through a pipeline. The gas phase outlet of the dimethyl carbonate top condenser is connected to the gas phase inlet of the vent condenser. The gas phase outlet of the vent condenser is connected to a vent elbow. The condensate outlets of the dimethyl carbonate top condenser and the vent condenser are connected to the dimethyl carbonate separation column reflux drum through a pipeline. The outlet of the dimethyl carbonate separation column reflux drum is connected to the inlet of the dimethyl carbonate cooler through the dimethyl carbonate separation column reflux pump. The outlet of the dimethyl carbonate cooler is connected to a crude dimethyl carbonate storage tank through a pipeline. A reflux pipeline c connected to the top of the dimethyl carbonate separation column is provided on the pipeline connected to the outlet of the dimethyl carbonate separation column reflux pump. The bottom liquid inlet of the dimethyl carbonate separation column reboiler and the gas phase outlet of the dimethyl carbonate separation column reboiler are respectively connected to the bottom of the dimethyl carbonate separation column tower kettle and the side of the dimethyl carbonate separation column tower kettle through pipelines. The heavy component outlet of the dimethyl carbonate separation column is connected to the inlet of the heavy component pump through a pipeline. The outlet of the heavy component pump is connected to a heavy component storage tank through a pipeline. A refined dimethyl oxalate side draw port is provided on the dimethyl carbonate separation column. The refined dimethyl oxalate side draw port is connected to the inlet of a refined dimethyl oxalate side draw tank through a pipeline. The outlet of the refined dimethyl oxalate side draw tank is connected to the inlet of the refined dimethyl oxalate pump through a pipeline. A refined dimethyl oxalate draw outlet is also provided at the bottom of the dimethyl carbonate separation column. The refined dimethyl oxalate draw outlet is connected to the pipeline connected to the inlet of the refined dimethyl oxalate pump through a pipeline provided with a cut-off valve. A balance pipe connected to the dimethyl carbonate separation column is provided on the refined dimethyl oxalate side draw tank. The outlet of the refined dimethyl oxalate pump is connected to the shell side inlet of a feed and discharge heat exchanger through a pipeline. The shell side outlet of the feed and discharge heat exchanger is connected to the inlet of the hot water cooler through a pipeline. A pipeline connected to the inlet of the refined dimethyl oxalate reflux cooler is provided on the pipeline connected to the shell side outlet of the feed and discharge heat exchanger. The outlet of the refined dimethyl oxalate reflux cooler is connected to the refined dimethyl oxalate reflux port of a dimethyl oxalate de-lighting column through a pipeline. The outlet of the hot water cooler is connected to a refined dimethyl oxalate storage tank.

[0008] As described above, the gas phase feed port in the middle of the dimethyl oxalate de-lighting column is higher than the liquid phase feed port in the middle of the dimethyl oxalate de-lighting column.

[0009] As described above, several layers of packing are provided in both the dimethyl oxalate de-lighting column and the dimethyl carbonate separation column.

[0010] As described above, the reflux port of the refined dimethyl oxalate of the dimethyl oxalate de-lighting tower is arranged on the side of the tower body of the dimethyl oxalate de-lighting tower below the highest packing layer of the dimethyl oxalate de-lighting tower.

[0011] As described above, the side draw port of the refined dimethyl oxalate is arranged on the side of the tower body of the dimethyl carbonate separation tower above the lowest packing layer of the dimethyl carbonate separation tower.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] 1. The high-temperature refined dimethyl oxalate exchanges heat with the crude dimethyl oxalate in the feed and discharge heat exchanger, heating the crude dimethyl oxalate with a lower temperature while reducing the temperature of the refined dimethyl oxalate, greatly reducing the heat consumption of the dimethyl oxalate de-lighting tower.

[0014] 2. In the dimethyl oxalate de-lighting tower, dimethyl oxalate is used to break the azeotrope of methanol and dimethyl carbonate, and methanol is rectified and separated. In the dimethyl carbonate separation tower, dimethyl carbonate is distilled and separated, thereby purifying dimethyl oxalate.

[0015] 3. In the process of purifying dimethyl oxalate, methanol and dimethyl carbonate are effectively separated, avoiding the selection of other boiling point depressants for separating methanol and dimethyl carbonate. Description of the Drawings

[0016] Figure 1 is a schematic structural diagram of the device of the present invention;

[0017] In the figure: 1 - feed and discharge heat exchanger; 2 - de-lighting tower feed tank; 3 - dimethyl oxalate de-lighting tower; 4 - de-lighting tower top condenser; 5 - de-lighting tower reflux tank; 6 - de-lighting tower reflux pump; 7 - de-lighting tower reboiler; 8 - de-lighting tower bottom pump; 9 - dimethyl carbonate separation tower; 10 - dimethyl carbonate tower top condenser; 11 - vent condenser; 12 - dimethyl carbonate separation tower reflux tank; 13 - dimethyl carbonate separation tower reflux pump; 14 - dimethyl carbonate cooler; 15 - refined dimethyl oxalate side draw tank; 16 - refined dimethyl oxalate pump; 17 - hot water cooler; 18 - heavy component pump; 19 - dimethyl carbonate separation tower reboiler; 20 - refined dimethyl oxalate reflux cooler. Detailed Embodiments

[0018] In order to enable those skilled in the art to more accurately understand the technical solution and working principle of the present invention, the following will be described in detail by way of examples.

[0019] In this embodiment, shut-off valves and bypass pipelines are provided before and after the control valve and flowmeter, and a shut-off valve is provided on the bypass pipeline; several pressure transmitters and several temperature transmitters are provided from the top to the bottom of the dimethyl oxalate light component removal tower 3 and the dimethyl carbonate separation tower 9; the heat source of the light component removal tower reboiler 7 and the dimethyl carbonate separation tower reboiler 19 is preferably steam; the cooling media of the light component removal tower top condenser 4, the dimethyl carbonate tower top condenser 10, the vent condenser 11, the dimethyl carbonate cooler 14, and the refined dimethyl oxalate reflux cooler are preferably circulating water.

[0020] Example 1

[0021] Refer to Figure 1 , the present invention includes a device for rectifying dimethyl oxalate in coal chemical industry, including a dimethyl oxalate light component removal device and a dimethyl carbonate separation device;

[0022] The dimethyl oxalate light component removal device includes a dimethyl oxalate light component removal tower 3, a light component removal tower reboiler 7, an inlet and outlet heat exchanger 1, a light component removal tower feed tank 2, a light component removal tower top condenser 4, a light component removal tower reflux tank 5, a light component removal tower reflux pump 6, and a light component removal tower bottom pump 8. The tube side inlet and the tube side outlet of the inlet and outlet heat exchanger 1 are respectively connected to the crude dimethyl oxalate storage tank and the inlet of the light component removal tower feed tank 2 through pipelines. A regulating valve, a flow transmitter, and a temperature transmitter are arranged on the pipeline connecting the tube side inlet of the inlet and outlet heat exchanger 1 and the crude dimethyl oxalate storage tank. A bypass pipeline of the inlet and outlet heat exchanger 1 communicating with the middle liquid phase feed port of the dimethyl oxalate light component removal tower 3 is arranged on the pipeline connecting the tube side inlet of the inlet and outlet heat exchanger 1. A temperature transmitter is arranged on the light component removal tower feed tank 2. The liquid phase outlet and the gas phase outlet of the light component removal tower feed tank 2 are respectively connected to the gas phase feed port in the middle of the dimethyl oxalate light component removal tower 3 and the liquid phase feed port in the middle of the dimethyl oxalate light component removal tower 3 through pipelines. The bottom liquid outlet of the dimethyl oxalate light component removal tower 3 is connected to the feed port of the dimethyl carbonate separation tower 9 through the light component removal tower bottom pump 8. A flow transmitter and a regulating valve are arranged on the pipeline connecting the bottom liquid outlet of the dimethyl oxalate light component removal tower 3 and the feed port of the dimethyl carbonate separation tower 9. A reflux pipeline a communicating with the bottom of the dimethyl oxalate light component removal tower 3 is arranged on the pipeline connecting the outlet of the light component removal tower bottom pump 8 and the feed port of the dimethyl carbonate separation tower 9. The bottom liquid inlet of the light component removal tower reboiler 7 and the gas phase outlet of the light component removal tower reboiler 7 are respectively communicated with the bottom of the dimethyl oxalate light component removal tower 3 and the side of the bottom of the dimethyl oxalate light component removal tower 3 through pipelines. The top gas phase outlet of the dimethyl oxalate light component removal tower 3 is connected to the gas phase inlet of the light component removal tower top condenser 4 through a pipeline. A pressure transmitter a is arranged on the pipeline connecting the top gas phase outlet of the dimethyl oxalate light component removal tower 3 and the gas phase inlet of the light component removal tower top condenser 4. The gas phase outlet of the light component removal tower top condenser 4 is connected to the compressor inlet. A regulating valve and a temperature transmitter are arranged on the pipeline connecting the gas phase outlet of the light component removal tower top condenser 4 and the compressor inlet. The condensate outlet of the light component removal tower top condenser 4 is connected to the inlet of the light component removal tower reflux tank 5 through a pipeline. A temperature transmitter is arranged on the pipeline connecting the condensate outlet of the light component removal tower top condenser 4 and the inlet of the light component removal tower reflux tank 5. The outlet of the light component removal tower reflux tank 5 is connected to the inlet of the light component removal tower reflux pump 6 through a pipeline. The outlet of the light component removal tower reflux pump 6 is connected to the methyl formate separation device through a pipeline. A flow transmitter and a regulating valve are arranged on the pipeline connecting the outlet of the light component removal tower reflux pump 6 and the methyl formate separation device. A reflux pipeline b connecting to the top of the dimethyl oxalate light component removal tower 3 is arranged on the pipeline connecting the outlet of the light component removal tower reflux pump 6 and the feed port of the methyl formate separation tower. A flow transmitter and a regulating valve are arranged on the reflux pipeline b;

[0023] The dimethyl carbonate separation device includes a dimethyl carbonate separation tower 9, a dimethyl carbonate separation tower reboiler 19, a dimethyl carbonate top condenser 10, a vent condenser 11, a dimethyl carbonate separation tower reflux drum 12, a dimethyl carbonate separation tower reflux pump 13, a dimethyl carbonate cooler 14, a dimethyl oxalate side draw tank 15, a refined dimethyl oxalate pump 16, a heavy component pump 18, a hot water cooler 17, and a refined dimethyl oxalate reflux cooler 20. The gas phase outlet at the top of the dimethyl carbonate separation tower 9 is connected to the gas phase inlet of the dimethyl carbonate top condenser 10 through a pipeline. The gas phase outlet of the dimethyl carbonate top condenser 10 is connected to the gas phase inlet of the vent condenser 11. The gas phase outlet of the vent condenser 11 is connected to a vent elbow. The condensate outlets of the dimethyl carbonate top condenser 10 and the vent condenser 11 are connected to the dimethyl carbonate separation tower reflux drum 12 through pipelines. Temperature transmitters are provided on the pipelines connected to the condensate outlet of the dimethyl carbonate top condenser 10 and the pipelines connected to the condensate outlet of the vent condenser 11. The outlet of the dimethyl carbonate separation tower reflux drum 12 is connected to the inlet of the dimethyl carbonate cooler 14 through the dimethyl carbonate separation tower reflux pump 13. The outlet of the dimethyl carbonate cooler 14 is connected to a crude dimethyl carbonate storage tank through a pipeline. A reflux pipeline c connected to the top of the dimethyl carbonate separation tower 9 is provided on the pipeline connected to the outlet of the dimethyl carbonate separation tower reflux pump 13. A regulating valve and a flowmeter are provided on the reflux pipeline c. A regulating valve and a flowmeter are provided on the pipeline connected to the inlet of the dimethyl carbonate cooler 14. The heavy component outlet of the dimethyl carbonate separation tower 9 is connected to the inlet of the heavy component pump 18 through a pipeline. The outlet of the heavy component pump 18 is connected to a heavy component storage tank through a pipeline. The bottom liquid inlet of the dimethyl carbonate separation tower reboiler 19 and the gas phase outlet of the dimethyl carbonate separation tower reboiler 19 are respectively connected to the bottom of the tower kettle of the dimethyl carbonate separation tower 9 and the side of the tower kettle of the dimethyl carbonate separation tower 9 through pipelines. A refined dimethyl oxalate side draw port is provided on the dimethyl carbonate separation tower 9. The refined dimethyl oxalate side draw port is connected to the inlet of the refined dimethyl oxalate side draw tank 15 through a pipeline. A regulating valve is provided on the pipeline connecting the refined dimethyl oxalate side draw port and the inlet of the refined dimethyl oxalate side draw tank 15. The outlet of the refined dimethyl oxalate side draw tank 15 is connected to the inlet of the refined dimethyl oxalate pump 16 through a pipeline. A refined dimethyl oxalate draw outlet is also provided at the tower kettle of the dimethyl carbonate separation tower 9. The refined dimethyl oxalate draw outlet is connected to the pipeline connected to the inlet of the refined dimethyl oxalate pump 16 through a pipeline provided with a cut-off valve. A balance pipe connected to the dimethyl carbonate separation tower 9 is provided on the refined dimethyl oxalate side draw tank 15. The outlet of the refined dimethyl oxalate pump 16 is connected to the shell side inlet of the feed and discharge heat exchanger 1 through a pipeline. The shell side outlet of the feed and discharge heat exchanger 1 is connected to the inlet of the hot water cooler 17 through a pipeline. A pipeline connected to the inlet of the refined dimethyl oxalate reflux cooler 20 is provided on the pipeline connected to the shell side outlet of the feed and discharge heat exchanger 1.The outlet of the dimethyl oxalate reflux cooler 20 is connected to the dimethyl oxalate reflux port of the dimethyl oxalate de-light tower 3 through a pipeline. The dimethyl oxalate reflux port of the dimethyl oxalate de-light tower 3 is arranged on the side of the dimethyl oxalate de-light tower 3 below the highest packing layer at the top of the dimethyl oxalate de-light tower 3. The outlet of the hot water cooler 17 is connected to the dimethyl oxalate storage tank. On the pipeline connected to the outlet of the dimethyl oxalate pump 16, reflux pipelines d and e are provided which are connected to the bottom of the dimethyl carbonate separation tower 9 and the dimethyl oxalate side draw tank 15.,

[0024] The gas-phase feed port in the middle of the dimethyl oxalate de-light tower 3 is higher than the liquid-phase feed port in the middle of the dimethyl oxalate de-light tower 3.

[0025] Three layers of packing are provided in both the dimethyl oxalate de-light tower 3 and the dimethyl carbonate separation tower 9.

[0026] The dimethyl oxalate reflux port of the dimethyl oxalate de-light tower 3 is arranged on the side of the tower body of the dimethyl oxalate de-light tower 3 below the highest packing layer.

[0027] The dimethyl oxalate side draw port is arranged on the side of the tower body of the dimethyl carbonate separation tower 9 above the lowest packing layer.

[0028] The working principle of the present invention is as follows: The crude dimethyl oxalate is heated by the feed and product heat exchanger 1 and then enters the light component removal tower feed tank 2, where gas-liquid separation is carried out. The liquid crude dimethyl oxalate enters the dimethyl oxalate light component removal tower 3 from the bottom of the light component removal tower feed tank 2, and the separated gas enters the dimethyl oxalate light component removal tower 3 from the top of the light component removal tower feed tank 2. It is heated and rectified in the dimethyl oxalate light component removal tower 3 by the light component removal tower reboiler 7. The process gas phase a is obtained at the top of the dimethyl oxalate light component removal tower 3. The process gas phase a is condensed by the light component removal tower top condenser 4. The condensed liquid phase enters the light component removal tower reflux tank 5, and the non-condensable gas goes to the compression device. The main components of the condensate in the light component removal tower reflux tank 5 are methanol and methyl formate. A part of the condensate in the light component removal tower reflux tank 5 is refluxed to the dimethyl oxalate light component removal tower 3, and the other part is sent to the methyl formate separation device. The bottom liquid of the dimethyl oxalate light component removal tower 3 after rectification enters the dimethyl carbonate separation tower 9 for heating and rectification. The process gas phase b is obtained at the top of the dimethyl carbonate separation tower 9. The process gas phase b is condensed by the dimethyl carbonate tower top condenser 10 and the vent condenser 11. The condensed liquid enters the dimethyl carbonate separation tower reflux tank 12, and the non-condensable gas goes to the vent. The main components of the condensate in the dimethyl carbonate separation tower reflux tank 12 are dimethyl carbonate and methanol. A part of the condensate in the dimethyl carbonate separation tower reflux tank 12 is refluxed to the dimethyl carbonate separation tower 9, and the other part is cooled by the dimethyl carbonate cooler 14 and then sent to the crude dimethyl carbonate storage tank. The refined dimethyl oxalate is taken out from the bottom of the dimethyl carbonate separation tower 9. The refined dimethyl oxalate enters the feed and product heat exchanger 1 to exchange heat with the crude dimethyl oxalate. The refined dimethyl oxalate after temperature reduction is divided into two parts. One part enters the hot water cooler 17 for further temperature reduction and then is sent to the refined dimethyl oxalate storage tank, and the other part of the refined dimethyl oxalate is cooled by the refined dimethyl oxalate reflux cooler 20 and then refluxed to the dimethyl oxalate light component removal tower 3. When the system is just started up, the purity of the refined dimethyl oxalate taken out from the bottom of the dimethyl carbonate separation tower 9 is relatively low. The refined dimethyl oxalate is selectively taken out from the side and enters the refined dimethyl oxalate side draw tank 15. The bottom liquid of the dimethyl carbonate separation tower 9 is sent to the heavy component storage tank by the heavy component pump 18.

[0029] As described in the above specific embodiments, they are only examples of the content of the present invention. Any modification and change made by those familiar with the present invention to this creation fall within the scope of the patent of the present invention, not limited to the embodiments described.

Claims

1. A dimethyl oxalate rectification device for coal chemical industry, characterized in that, It includes a dimethyl oxalate light component removal unit and a dimethyl carbonate separation unit; the dimethyl oxalate light component removal unit includes a dimethyl oxalate light component removal tower, a light component removal tower reboiler, an inlet and outlet heat exchanger, a light component removal tower feed tank, a light component removal tower top condenser, a light component removal tower reflux tank, a light component removal tower reflux pump, and a light component removal tower bottom pump. The tube side inlet and the tube side outlet of the inlet and outlet heat exchanger are respectively connected to the crude dimethyl oxalate storage tank and the inlet of the light component removal tower feed tank through pipelines. The liquid phase outlet and the gas phase outlet of the light component removal tower feed tank are respectively connected to the gas phase feed port in the middle of the dimethyl oxalate light component removal tower and the liquid phase feed port in the middle of the dimethyl oxalate light component removal tower through pipelines. The bottom liquid outlet of the dimethyl oxalate light component removal tower is connected to the feed port of the dimethyl carbonate separation tower through the light component removal tower bottom pump. A reflux pipeline a communicating with the bottom of the dimethyl oxalate light component removal tower is provided on the pipeline connecting the outlet of the light component removal tower bottom pump and the feed port of the dimethyl carbonate separation tower. The bottom liquid inlet of the light component removal tower reboiler and the gas phase outlet of the light component removal tower reboiler are respectively communicated with the bottom of the dimethyl oxalate light component removal tower and the side of the dimethyl oxalate light component removal tower bottom through pipelines. The top gas phase outlet of the dimethyl oxalate light component removal tower is connected to the gas phase inlet of the light component removal tower top condenser through a pipeline. The gas phase outlet of the light component removal tower top condenser is connected to the compressor inlet. The condensed liquid phase outlet of the light component removal tower top condenser is connected to the inlet of the light component removal tower reflux tank through a pipeline. The outlet of the light component removal tower reflux tank is connected to the inlet of the light component removal tower reflux pump through a pipeline. The outlet of the light component removal tower reflux pump is connected to the methyl formate separation unit through a pipeline. A reflux pipeline b connecting to the top of the dimethyl oxalate light component removal tower is provided on the pipeline connecting the outlet of the light component removal tower reflux pump and the feed port of the methyl formate separation tower; The dimethyl carbonate separation device includes a dimethyl carbonate separation column, a dimethyl carbonate separation column reboiler, a dimethyl carbonate top condenser, a vent condenser, a dimethyl carbonate separation column reflux drum, a dimethyl carbonate separation column reflux pump, a dimethyl carbonate cooler, a refined dimethyl oxalate pump, a heavy component pump, a hot water cooler, a refined dimethyl oxalate reflux cooler. The gas-phase outlet at the top of the dimethyl carbonate separation column is connected to the gas-phase inlet of the dimethyl carbonate top condenser through a pipeline. The gas-phase outlet of the dimethyl carbonate top condenser is connected to the gas-phase inlet of the vent condenser. The gas-phase outlet of the vent condenser is connected to a vent elbow. The condensate liquid outlets of the dimethyl carbonate top condenser and the vent condenser are connected to the dimethyl carbonate separation column reflux drum through a pipeline. The outlet of the dimethyl carbonate separation column reflux drum is connected to the inlet of the dimethyl carbonate cooler through the dimethyl carbonate separation column reflux pump. The outlet of the dimethyl carbonate cooler is connected to a crude dimethyl carbonate storage tank through a pipeline. A reflux pipeline c connected to the top of the dimethyl carbonate separation column is provided on the pipeline connected to the outlet of the dimethyl carbonate separation column reflux pump. The bottom liquid inlet of the dimethyl carbonate separation column reboiler and the gas-phase outlet of the dimethyl carbonate separation column reboiler are respectively connected to the bottom of the dimethyl carbonate separation column tower kettle and the side of the dimethyl carbonate separation column tower kettle through pipelines. The heavy component outlet of the dimethyl carbonate separation column is connected to the inlet of the heavy component pump through a pipeline. The outlet of the heavy component pump is connected to a heavy component storage tank through a pipeline. A refined dimethyl oxalate side draw port is provided on the dimethyl carbonate separation column. The refined dimethyl oxalate side draw port is connected to the inlet of a refined dimethyl oxalate side draw tank through a pipeline. The outlet of the refined dimethyl oxalate side draw tank is connected to the inlet of the refined dimethyl oxalate pump through a pipeline. A refined dimethyl oxalate draw outlet is also provided at the bottom of the dimethyl carbonate separation column. The refined dimethyl oxalate draw outlet is connected to the pipeline connected to the inlet of the refined dimethyl oxalate pump through a pipeline provided with a cut-off valve. A balance pipe connected to the dimethyl carbonate separation column is provided on the refined dimethyl oxalate side draw tank. The outlet of the refined dimethyl oxalate pump is connected to the shell-side inlet of a feed and discharge heat exchanger through a pipeline. The shell-side outlet of the feed and discharge heat exchanger is connected to the inlet of the hot water cooler through a pipeline. A pipeline connected to the inlet of the refined dimethyl oxalate reflux cooler is provided on the pipeline connected to the shell-side outlet of the feed and discharge heat exchanger. The outlet of the refined dimethyl oxalate reflux cooler is connected to the refined dimethyl oxalate reflux port of the dimethyl oxalate de-lighting column through a pipeline. The outlet of the hot water cooler is connected to a refined dimethyl oxalate storage tank; The gas-phase feed port in the middle of the dimethyl oxalate de-lighting column is higher than the liquid-phase feed port in the middle of the dimethyl oxalate de-lighting column; A plurality of layers of packing are provided in both the dimethyl oxalate de-lighting column and the dimethyl carbonate separation column; The refined dimethyl oxalate reflux port of the dimethyl oxalate de-lighting column is arranged on the side of the dimethyl oxalate de-lighting column tower body below the highest packing layer of the dimethyl oxalate de-lighting column; The refined dimethyl oxalate side draw port is arranged on the side of the dimethyl carbonate separation column tower body above the lowest packing layer of the dimethyl carbonate separation column.

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