System for switching production of DMC and EMC

Abstract

The utility model relates to a system for switching production of DMC and EMC. The system comprises a reactive distillation tower, a high-pressure separation tower, a low-pressure separation tower, a methanol recovery tower, a light component removal tower, a heavy component removal tower and a pre-reactor. According to the DMC production line, flexible switching production between DMC and EMC can be achieved, the requirements of different markets are met, due to the flexibility, the utilization rate of the production line is increased, the market competitiveness of enterprises is enhanced, in the DMC production process, through the steps of DMC reaction, separation, refining, methanol recovery and the like, the high quality and purity of products are ensured, and the production cost is reduced. In the EMC production process, the efficient and environment-friendly production process is also achieved through the steps of reaction, methanol recovery, refining and the like, the system for switching production of DMC and EMC has remarkable advantages and effects in the aspects of catalyst application, production switching, technological processes, energy conservation, environmental protection, modular design and the like, and new breakthrough and progress are brought to the field of chemical production.

Description

Technical Field

[0001] The utility model relates to the technical field of carbonate production, in particular to a low-energy consumption, green carbonate product production system; more specifically, to a low-energy consumption, green production system for dimethyl carbonate and ethyl methyl carbonate. Background Art

[0002] At present, the production of dimethyl carbonate DMC / ethyl methyl carbonate EMC has reliable technology source and stable raw material supply.

[0003] DMC is a low-toxic, environmentally friendly and widely used chemical raw material. It is an important organic synthesis intermediate. Its molecular structure contains carbonyl, methyl and methoxy functional groups, and it has a variety of reaction properties. It is safe, convenient, less polluting and easy to transport in production. In addition, DMC, as a raw material for lithium battery electrolyte, has received widespread attention in this field.

[0004] EMC is a high value-added chemical product that has emerged in recent years. It contains active reaction groups such as methyl, ethyl and carbonyl groups, can be used in the lithium battery industry, and has good development prospects.

[0005] A system for switching the production of DMC / EMC is currently disclosed. The technical solution is: when producing EMC, DMC is mixed with ethanol and then enters the pre-reactor through a pipeline. The upper and middle parts of the EMC reaction distillation tower are connected to the DMC feed pump through a pipeline, and the top is connected to the reflux tank through a pipeline. A part of the material at the bottom of the reflux tank returns to the DMC reaction distillation tower through a pipeline, and a part of the material goes to the high-pressure separation tower through a pipeline. The lower and middle parts of the DMC reaction distillation tower are connected to two methanol feeds through a pipeline. When producing EMC, the upper and middle parts of the EMC reaction distillation tower are connected to the DMC / ethanol pre-reactor discharge through a pipeline, and the top is connected to the reflux tank through a pipeline. A part of the material at the bottom of the reflux tank returns to the EMC reaction distillation tower through a pipeline, and a part of the material goes to the high-pressure separation tower through a pipeline, and the bottom enters the de-DMC / ethanol tower through a pipeline. This process scheme does not require the provision of a catalyst separation device.

[0006] A system for switching the production of DMC and EMC is currently disclosed, which includes (a) using a heterogeneous catalyst to catalyze the reaction of EC and methanol to produce DMC, and catalyze the reaction of DMC and ethanol to produce EMC. (b) If EC and methanol are catalyzed to react to produce DMC, DMC is separated and refined from the condensate at the top of the reaction distillation tower; methanol is separated from the bottom liquid of the tower and EG is recovered. (c) If DMC and ethanol are catalyzed to react to produce EMC, methanol is separated and recovered from the condensate at the top of the reaction distillation tower; EMC is separated and refined from the bottom liquid of the tower.

[0007] At present, the main methods for EMC synthesis are phosgene method, oxidative carbonylation method and ester exchange method.

[0008] This reaction mainly adopts the DMC and ethanol ester exchange method in the ester exchange method:

[0009] Transesterification of DMC with ethanol

[0010] CH3COCOOCH3+C2H5OH=

[0011] CH3OH+ C2H5COCOOC2H5+ CH3COCOOC2H5

[0012] The transesterification of DMC and ethanol to synthesize EMC is also a reversible reaction, and its equilibrium constant is larger than that of the transesterification of DMC and DEC to synthesize EMC. The reaction uses a fixed bed catalyst. When DMC is in an appropriate amount, EMC is mainly produced; when ethanol is in excess, ethanol will further react with EMC to produce DEC.

[0013] In the EMC synthesis method, the reactive distillation process forms three groups of azeotropes in the reaction product, which is difficult to separate and purify. The transesterification reaction is a reversible reaction. Due to the limitation of equilibrium, the yield of the target product EMC is not high.

[0014] In summary, the current DMC / EMC production processes all use homogeneous methods, which require the installation of catalyst and material separation devices; the catalyst needs to be recycled, which increases energy consumption and produces waste liquid, etc. The use of new heterogeneous catalysts, reduced production energy consumption, and the development of environmentally friendly green carbonate production can meet the trend of today's society. Utility Model Content

[0015] In order to solve the problems of the prior art, the utility model provides a system for switching the production of DMC and EMC.

[0016] In order to solve the above technical problems, the utility model is realized by the following technical scheme: a system for switching the production of DMC and EMC, comprising a reaction distillation tower, a high-pressure separation tower, a low-pressure separation tower, a methanol recovery tower, a light removal tower, a heavy removal tower and a pre-reactor, wherein a DMC production system and an EMC production system are included, and the reaction distillation tower, the high-pressure separation tower, the low-pressure separation tower, the methanol recovery tower, the light removal tower, the heavy removal tower and the pre-reactor are connected by pipelines;

[0017] The top of the reaction distillation tower is connected to the condenser E201 through a pipeline output, the output end of the condenser E201 is fixedly connected to the top reflux tank V201, and the output end of the top reflux tank V201 is fixedly connected to the top input end of the reaction distillation tower through a pump body;

[0018] The top of the high-pressure separation tower is connected to the condenser E301 through a pipeline output, the output end of the condenser E301 is fixedly connected to the reflux tank V301, and the output end of the reflux tank V301 is fixedly connected to the top input end of the high-pressure separation tower through a pump body;

[0019] The top of the low-pressure separation tower is connected to the top condenser E302 through a pipeline output, the output end of the top condenser E302 is fixedly connected to the reflux tank V302, and the output end of the reflux tank V302 is fixedly connected to the top input end of the low-pressure separation tower through a pump body;

[0020] The top of the methanol recovery tower is connected to a condenser E401 through a pipeline output, the output end of the condenser E401 is fixedly connected to a reflux tank V401, and the output end of the reflux tank V401 is fixedly connected to the top input end of the methanol recovery tower through a pump body;

[0021] The top of the light-removing tower is connected to the top condenser E501 through a pipeline output, the output end of the top condenser E501 is fixedly connected to the reflux tank V501, and the output end of the reflux tank V501 is fixedly connected to the top input end of the light-removing tower through a pump body;

[0022] The top of the de-weighting tower is connected to the condenser E502 through a pipeline output, the output end of the condenser E502 is fixedly connected to the reflux tank V502, and the output end of the reflux tank V502 is fixedly connected to the top input end of the de-weighting tower through a pump body;

[0023] The top of the pre-reactor is connected to a heat exchanger through a pipeline output.

[0024] Preferably, the DMC production system includes a reaction distillation tower, a high-pressure separation tower, a low-pressure separation tower, a methanol recovery tower, a light removal tower, and a heavy removal tower. EC and methanol are respectively input into one side input end of the reaction distillation tower, the bottom output end of the reaction distillation tower is connected to the methanol recovery tower, and the output end of the reflux tank V401 is connected to the pipeline for inputting methanol through a pump body.

[0025] Preferably, the output end of the reflux tank V301 is connected to the output end of the reaction distillation tower through a pump body; the output end of the top reflux tank V201 is fixedly connected to the input ends of the high-pressure separation tower and the low-pressure separation tower respectively through a pump body.

[0026] Preferably, the bottom output end of the high-pressure separation tower is fixedly connected to the input end of the low-pressure separation tower, and the bottom output end of the low-pressure separation tower is fixedly connected to the input end of the light-removal tower through a pump body.

[0027] Preferably, the bottom output end of the light-removing tower is fixedly connected to the input end of the heavy-removing tower through a pump body, and the output ends of the reflux tank V501, the heavy-removing tower and the reflux tank V502 are connected through the pump body and output industrial-grade DMC, and the output end of the heavy-removing tower outputs battery-grade DMC.

[0028] Preferably, the DMC production system includes a reactive distillation tower, a high-pressure separation tower, a low-pressure separation tower, a methanol recovery tower, a light-removal tower, a heavy-removal tower and a pre-reactor, one side input end of the reactive distillation tower is connected to the pre-reactor, the input end of the pre-reactor is fixedly connected to a heat exchanger, and DMC and ethanol are input to the input end of the heat exchanger.

[0029] Preferably, the output ends of the tower top reflux tank V201 and the reflux tank V302 are respectively fixedly connected to the input ends of the high-pressure separation tower through pump bodies, and the output end of the high-pressure separation tower is fixedly connected to an input end of the reaction distillation tower.

[0030] Preferably, the output end of the reflux tank V301 is fixedly connected to the low-pressure separation tower through a pump body, and the bottom output end of the high-pressure separation tower is output to the methanol storage tank through the pump body.

[0031] Preferably, the output end of the reflux tank V401 is fixedly connected to an input end of the reaction distillation tower through a pump body, the bottom output end of the deweighting tower is fixedly connected to an input end of the reaction distillation tower through a pump body, and the output end of the reflux tank V501 is fixedly connected to an input end of the reaction distillation tower through a pump body.

[0032] Preferably, the bottom output end of the methanol recovery tower is fixedly connected to an input end of the light-removing tower through a pump body, the bottom output end of the light-removing tower is fixedly connected to an input end of the heavy-removing tower through a pump body, the output end of the reflux tank V502 outputs industrial-grade EMC through the pump body, and an output end of the heavy-removing tower outputs battery-grade EMC.

[0033] Specifically: a system for switching the production of DMC and EMC. The system uses the same heterogeneous catalyst. There is no separation problem between the catalyst and the material in the reaction, which reduces production energy consumption. After the catalyst is deactivated, it can be directly recovered in one go.

[0034] Preferably, when producing DMC, it includes DMC reaction, DMC separation, DMC refining and methanol recovery in sequence; DMC reaction includes a feed section, a reaction distillation section, DMC separation includes a high-pressure separation section and a low-pressure separation section, DMC refining includes a light removal section and a heavy removal section, and methanol recovery includes a separation and recovery section. When producing EMC, it includes EMC reaction, methanol recovery and EMC refining in sequence, EMC reaction includes a feed section, a pre-reaction section, a reaction distillation section, methanol recovery includes a high-pressure separation section and a low-pressure separation section, and EMC refining includes a light removal section and a heavy removal section.

[0035] The DMC reaction consists of a reaction feed section and a reaction distillation section; the EMC reaction consists of a reaction feed section, a pre-reaction section and a reaction distillation section.

[0036] The methanol feed of the DMC reaction feed section is divided into two routes, one of which is connected to the top of the high-pressure separation tower, and the other is connected to the boundary methanol raw material tank. The ethanol feed of the EMC reaction feed is divided into two routes, one of which is connected to the ethanol feed and the pre-reactor, and the other is connected to the reaction distillation tower and the top of the deethanol / DMC tower.

[0037] The DMC reaction feed section EC feed is connected to the EC unit EC flash tank bottom delivery pump. The EMC reaction feed DMC feed is divided into two routes, one is connected to the high-pressure separation tower kettle, and the other is connected to the DMC raw material delivery pump.

[0038] Preferably, in the production of EMC, the high-pressure separation tower kettle of the DMC recovery high-pressure separation section is connected to the EMC reaction distillation tower, and the tower top is connected to the low-pressure separation section. In the production of EMC, the low-pressure separation tower kettle of the DMC recovery low-pressure separation section is connected to the methanol raw material tank, and the tower top is connected to the high-pressure separation section.

[0039] Produce EMC, the EMC refining and light removal section includes a deethanol / DMC tower and a light removal tower. The top of the EMC distillation deethanol / DMC tower is connected to the top condenser and the top reflux tank in sequence, and the top reflux pump is divided into two paths, one is connected to the tower body of the deethanol / DMC tower, and the other is connected to the tower body of the EMC reaction distillation tower, and the tower kettle is connected to the light removal tower. The top of the EMC refining and light removal tower is connected to the top condenser and the top reflux tank in sequence, and the top reflux pump is divided into two paths, one is connected to the tower body of the light removal tower, and the other is connected to the tower body of the EMC reaction distillation tower, and the tower kettle is connected to the heavy removal section.

[0040] To produce EMC, the EMC refining and de-weighting section includes a de-weighting tower. The top of the EMC refining and de-weighting tower is connected to the top condenser and the top reflux tank in sequence. The top reflux pump is divided into two paths, one of which is used as battery-grade EMC for extraction, and the other is connected to the tower body of the de-weighting tower. The tower kettle is connected to the tower body of the EMC reactive distillation tower.

[0041] In producing EMC, the pre-reactor and the reaction distillation tower of the EMC reaction unit are both solid-supported catalysts with a loading amount of 5 to 20%.

[0042] The DMC reaction distillation tower is a packed tower.

[0043] The beneficial effects of the utility model are:

[0044] 1. The utility model can realize flexible switching production between DMC and EMC, meeting the needs of different markets. This flexibility not only improves the utilization rate of the production line, but also enhances the market competitiveness of the enterprise. In the DMC production process, through multiple steps such as DMC reaction, separation, refining and methanol recovery, the high quality and purity of the product are ensured. In the EMC production process, through the steps of reaction, methanol recovery and refining, an efficient and environmentally friendly production process is also achieved. The system for switching production of DMC and EMC has significant advantages and effects in catalyst application, production switching, process flow, energy conservation and environmental protection, and modular design, bringing new breakthroughs and progress to the field of chemical production;

[0045] 2. The system uses the same heterogeneous catalyst, which not only simplifies the production process, but also avoids the separation problem of catalyst and materials, thereby significantly reducing production energy consumption. In addition, the one-time direct recovery of the catalyst after deactivation not only improves the efficiency of the catalyst, but also reduces the pollution of the waste catalyst to the environment. By optimizing the process flow and the use of catalysts, the production energy consumption is reduced and the impact on the environment is reduced. At the same time, the recovery and reuse of catalysts also reduce the generation of waste, which is in line with the concept of sustainable development. The system adopts a modular design, so that each production link can be operated and optimized independently. This not only improves the flexibility of production, but also facilitates later maintenance and upgrading. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the DMC production process of Example 1 of the utility model.

[0047] Figure 2 This is a schematic diagram of the EMC production process of the second embodiment of the utility model.

[0048] Figure 1-2 In: 1. Reaction distillation tower; 2. High-pressure separation tower; 3. Low-pressure separation tower; 4. Methanol recovery tower; 5. Light-removal tower; 6. Heavy-removal tower; 7. Pre-reactor; 71. Heat exchanger; 11. Condenser E201; 12. Top reflux tank V201; 21. Condenser E301; 22. Reflux tank V301; 31. Top condenser E302; 32. Reflux tank V302; 41. Condenser E401; 42. Reflux tank V401; 51. Top condenser E501; 52. Reflux tank V501; 61. Condenser E502; 62. Reflux tank V502. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0050] Embodiment 1: Figure 1A system for switching production of DMC and EMC is shown. For DMC production, the raw material EC is pumped from the tank area into the reaction distillation tower T201. Methanol enters the reaction section of the reaction distillation tower T201 in two ways. One way is pumped from the raw material tank area into the reaction distillation tower T201, and the other way is extracted from the top of the high-pressure separation tower T301 and enters the reaction distillation tower T201. The operating parameters of the reaction distillation tower T201 are as follows: the top temperature is controlled at 65-70°C, the pressure is controlled at 0-5kpa, the bottom temperature is controlled at 80-90°C, and the raw material mass ratio is controlled at EC: methanol = 1:3-1:4. The top material of the reaction distillation tower T201 is condensed to 60°C by the condenser E201 and enters the top reflux tank V201. A part of the material at the bottom of the V201 tank is pumped to the high-pressure separation tower T301, and a part enters the tower body of the reaction distillation tower T201 as reflux. The bottom material of the T201 tower is pumped to the methanol recovery tower T401. The operating conditions of the high-pressure separation tower T301 are as follows: top pressure 1.6-1.8Mpa, top temperature 150-165°C, bottom temperature 200-210°C. The top materials DMC and methanol of the high-pressure separation tower T301 are cooled to 130°C by the condenser E301 and enter the reflux tank V301. Part of the material at the bottom of the V301 tank is pumped as methanol feed to T201, and part is used as reflux of T301. The mass ratio of methanol to DMC is 1:9, and the mass ratio of DMC to methanol at the bottom of the tower is 9:1, and enters the low-pressure separation tower T302. The operating conditions of the low-pressure separation tower T302 are as follows: the top pressure is controlled at 0.2-0.4 MPa, the top temperature is controlled at 110-120°C, the bottom temperature is controlled at 140-150°C, the mass ratio of the top material DMC to methanol is 2:8, and it is cooled to 100°C by the top condenser E302 and enters the reflux tank V302. Part of the material at the bottom of the V302 tank is pumped as the reflux of T302, and part is used as the feed of the high-pressure separation tower T301. The DMC content in the bottom of the tower reaches more than 99.8%, and it is directly pumped into the distillation section for refining operation.First, the light components are removed from the light components removal tower T501. The operating conditions of the light components removal tower T501 are as follows: the top pressure is controlled at 0.01~0.02 Mpa. The tower top temperature is controlled at 120-128°C, the tower bottom temperature is controlled at 130-135°C, the tower top material is cooled to 90°C by condenser E501 and enters the reflux tank V501, part of the V501 tank bottom material is pumped to the tank area as industrial-grade DMC, and part is used as reflux of T501, and the bottom material is pumped to the deweighting tower T502; it enters the deweighting tower T502 to remove heavy components. The operating conditions of the deweighting tower T502 are: the tower top pressure is controlled at 20-30KPaA, the tower top temperature is controlled at 40-50°C, the bottom temperature is controlled at 50-60°C, the T502 tower top material is cooled to 37°C by condenser E502 and enters the reflux tank V502, part of the V502 tank bottom material is pumped as reflux of T502, and part is transported to the finished product tank area as process-grade DMC, and battery-grade DMC is extracted from the side line and transported to the finished product tank area by pump.

[0051] T401 operating parameters: the tower top pressure is controlled at 40-50KPaA, the tower top temperature is controlled at 40-50℃, the tower bottom temperature is controlled at 150-160℃, the tower top material is cooled to 40℃ by condenser E401 and enters the reflux tank V401. Part of the material at the bottom of V401 is pumped as reflux of T401, and part is used as methanol feed of T201 tower. The EG extracted from the tower bottom is pumped to the EG processing unit.

[0052] Embodiment 2: Figure 2 A system for switching production of DMC and EMC is shown, in which EMC production: raw material DMC enters the reaction distillation tower in two ways, one is pumped into the reaction distillation tower from the raw material tank area, and the other is from the bottom of the high-pressure separation tower T301 to enter the reaction distillation tower; ethanol enters the reaction section in two ways, one is pumped into the reaction distillation tower from the raw material tank area, and the other is from the top of the DMC removal and ethanol tower T401 to enter the reaction distillation tower; the DMC transported from the tank area is mixed with ethanol and reaches 126°C through the heat exchanger E101, and enters the pre-reactor V101, in which a part of DMC reacts with methanol and enters the reaction distillation tower T201; the top temperature of the reaction distillation tower is controlled at 60-70°C, the pressure is controlled at 10-25kpa, the bottom temperature is controlled at 80-85°C, and the raw material mass ratio: DMC: ethanol = 1:2-1:4. The top gas phase of the reaction distillation tower T201 is condensed to 50°C by the condenser E201 and enters the top reflux tank V201. Part of the material at the bottom of the V201 tank is transported to the high-pressure separation tower T301 by a pump, and part of it enters the T201 tower body as reflux; the material in the bottom of the tower is transported to the EMC refining section by a pump.

[0053] Part of the material at the bottom of tank V201 enters the high-pressure separation tower T301. The operating parameters of the high-pressure separation tower T301 are: top pressure 1.5-1.8Mpa, top temperature 110-120℃, bottom temperature 150-160℃. DMC and methanol produced from the top of T301 are cooled to 80℃ by condenser E301 and enter the reflux tank V301. Part of the material at the bottom of tank V301 is used as reflux of T301 through a pump, and part of it is used as feed for the low-pressure separation tower T302. DMC produced from the bottom of the tower enters the reaction distillation tower T201. The operating conditions of the low-pressure separation tower T302 are as follows: tower top pressure 0.2~0.4Mpa, tower top temperature 80~90℃, tower bottom temperature 110~120℃. DMC and methanol produced from the top of T302 are cooled to 60℃ by condenser E301 and enter the reflux tank V302. Part of the material at the bottom of V302 is pumped as reflux of T302, and part is used as feed of the high-pressure separation tower T301. The methanol produced from the bottom of the tower is transported to the raw material tank area by pump.

[0054] The materials in the bottom of T201 first enter the EMC refining section to remove DMC and ethanol tower T401. The operating conditions of T401 are: top pressure 20-30Kpa, top temperature 90-105℃, bottom temperature 130-140℃. DMC and ethanol produced from the top of T401 are cooled to 70℃ by condenser E401 and enter the reflux tank V401. Part of the materials at the bottom of V401 are pumped as reflux of T401, and part are used as feed of reactive distillation tower T201. EMC / DMC produced from the bottom of the tower enters the lightness removal tower T501. The operating conditions of the light-removal tower T501 are as follows: the top pressure is controlled at 20Kpa, the top temperature is controlled at 100-110℃, the bottom temperature is controlled at 130-145℃, the top gas is transported through the top condenser E501 to the reflux tank V501, a part of the V501 tank is pumped out as the reflux of T501, and a part is extracted as the feed of T201; the bottom of the tower is extracted into the heavy-removal tower T502 as the raw material of T502. Operating conditions of deweighting tower T502: top pressure is controlled at 20Kpa, top temperature is controlled at 95-105℃, bottom temperature is controlled at 130-140℃, top output is controlled at 80℃ through condenser E502, and then enters reflux tank V502. The material at the bottom of V502 is pumped, part of which is transported to the product tank area as industrial-grade EMC, and part of which is used as reflux of T502 tower. Battery-grade EMC is pumped to the finished product tank area through the side line, and the bottom output is pumped to T201 to participate in the ester exchange reaction.

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for switching the production of DMC and EMC, comprising a reaction distillation tower (1), a high-pressure separation tower (2), a low-pressure separation tower (3), a methanol recovery tower (4), a light-removal tower (5), a heavy-removal tower (6) and a pre-reactor (7), wherein the system includes a DMC production system and an EMC production system, and is characterized in that: The reactive distillation tower (1), the high-pressure separation tower (2), the low-pressure separation tower (3), the methanol recovery tower (4), the light-removal tower (5), the heavy-removal tower (6) and the pre-reactor (7) are connected via pipelines; The top of the reaction distillation tower (1) is connected to a condenser E201 (11) via a pipeline output, the output end of the condenser E201 (11) is fixedly connected to a tower top reflux tank V201 (12), and the output end of the tower top reflux tank V201 (12) is fixedly connected to the top input end of the reaction distillation tower (1) via a pump body; The top of the high-pressure separation tower (2) is connected to a condenser E301 (21) via a pipeline output, the output end of the condenser E301 (21) is fixedly connected to a reflux tank V301 (22), and the output end of the reflux tank V301 (22) is fixedly connected to the top input end of the high-pressure separation tower (2) via a pump body; The top of the low-pressure separation tower (3) is connected to a tower top condenser E302 (31) via a pipeline output, the output end of the tower top condenser E302 (31) is fixedly connected to a reflux tank V302 (32), and the output end of the reflux tank V302 (32) is fixedly connected to the top input end of the low-pressure separation tower (3) via a pump body; The top of the methanol recovery tower (4) is connected to a condenser E401 (41) via a pipeline output, the output end of the condenser E401 (41) is fixedly connected to a reflux tank V401 (42), and the output end of the reflux tank V401 (42) is fixedly connected to the top input end of the methanol recovery tower (4) via a pump body; The top of the light-removal tower (5) is connected to a tower top condenser E501 (51) via a pipeline output, the output end of the tower top condenser E501 (51) is fixedly connected to a reflux tank V501 (52), and the output end of the reflux tank V501 (52) is fixedly connected to the top input end of the light-removal tower (5) via a pump body; The top of the deweighting tower (6) is connected to a condenser E502 (61) via a pipeline output, the output end of the condenser E502 (61) is fixedly connected to a reflux tank V502 (62), and the output end of the reflux tank V502 (62) is fixedly connected to the top input end of the deweighting tower (6) via a pump body; The top end of the pre-reactor (7) is connected to a heat exchanger (71) via a pipeline output.

2. A system for switching production of DMC and EMC according to claim 1, characterized in that: The DMC production system comprises a reaction distillation tower (1), a high-pressure separation tower (2), a low-pressure separation tower (3), a methanol recovery tower (4), a light-removal tower (5), and a heavy-removal tower (6); EC and methanol are respectively input into one side input end of the reaction distillation tower (1); the bottom output end of the reaction distillation tower (1) is connected to the methanol recovery tower (4); and the output end of the reflux tank V401 (42) is connected to a pipeline for inputting methanol via a pump body.

3. A system for switching production of DMC and EMC according to claim 2, characterized in that: The output end of the reflux tank V301 (22) is connected to the output end of the reaction distillation tower (1) through a pump body; the output end of the tower top reflux tank V201 (12) is fixedly connected to the input ends of the high-pressure separation tower (2) and the low-pressure separation tower (3) through a pump body.

4. A system for switching production of DMC and EMC according to claim 3, characterized in that: The bottom output end of the high-pressure separation tower (2) is fixedly connected to the input end of the low-pressure separation tower (3), and the bottom output end of the low-pressure separation tower (3) is fixedly connected to the input end of the light-removal tower (5) via a pump body.

5. A system for switching production of DMC and EMC according to claim 4, characterized in that: The bottom output end of the light-removing tower (5) is fixedly connected to the input end of the heavy-removing tower (6) via a pump body; the output ends of the reflux tank V501 (52), the heavy-removing tower (6) and the reflux tank V502 (62) are connected through the pump body and output industrial-grade DMC; the output end of the heavy-removing tower (6) outputs battery-grade DMC.

6. The system for switching production of DMC and EMC according to claim 1, characterized in that: The DMC production system comprises a reaction distillation tower (1), a high-pressure separation tower (2), a low-pressure separation tower (3), a methanol recovery tower (4), a light-removal tower (5), a heavy-removal tower (6) and a pre-reactor (7); an input end on one side of the reaction distillation tower (1) is connected to the pre-reactor (7); a heat exchanger (71) is fixedly connected to the input end of the pre-reactor (7); and DMC and ethanol are input to the input end of the heat exchanger (71).

7. A system for switching production of DMC and EMC according to claim 6, characterized in that: The output ends of the tower top reflux tank V201 (12) and the reflux tank V302 (32) are respectively fixedly connected to the input end of the high-pressure separation tower (2) through a pump body, and the output end of the high-pressure separation tower (2) is fixedly connected to an input end of the reaction distillation tower (1).

8. The system for switching production of DMC and EMC according to claim 7, characterized in that: The output end of the reflux tank V301 (22) is fixedly connected to the low-pressure separation tower (3) through a pump body, and the bottom output end of the high-pressure separation tower (2) is output to the methanol storage tank through the pump body.

9. A system for switching production of DMC and EMC according to claim 8, characterized in that: The output end of the reflux tank V401 (42) is fixedly connected to an input end of the reaction distillation tower (1) through a pump body, the bottom output end of the deweighting tower (6) is fixedly connected to an input end of the reaction distillation tower (1) through a pump body, and the output end of the reflux tank V501 (52) is fixedly connected to an input end of the reaction distillation tower (1) through a pump body.

10. A system for switching production of DMC and EMC according to claim 9, characterized in that: The bottom output end of the methanol recovery tower (4) is fixedly connected to an input end of the light removal tower (5) through a pump body, and the bottom output end of the light removal tower (5) is fixedly connected to an input end of the heavy removal tower (6) through a pump body. The output end of the reflux tank V502 (62) outputs industrial-grade EMC through the pump body, and an output end of the heavy removal tower (6) outputs battery-grade EMC.

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