A methyl ethyl carbonate reaction apparatus with a vacuum negative pressure system

Abstract

The application relates to the technical field of chemical equipment, and provides a methyl ethyl carbonate reaction equipment with a vacuum negative pressure system, which comprises a reaction kettle main body, a supporting frame, a vacuum negative pressure control assembly, a stirring power assembly and a volatile recovery assembly; the reaction kettle main body is fixed on the supporting frame and is provided with an inner lining reaction bladder and a heat conducting oil circulating jacket; the vacuum negative pressure control assembly comprises a vacuum buffer tank, a vacuum pump, an electromagnetic proportional regulating valve and a pressure transmitter, and realizes pressure stabilization through feedback regulation and compensation of gas volume; the volatile recovery assembly comprises a first-stage condenser, a second-stage condenser and corresponding collection tanks connected in series. The application realizes accurate and stable control of the vacuum degree in the reaction kettle, improves the volatile component recovery rate, and guarantees the continuity of the reaction of heat-sensitive materials and the product purity.

Description

Technical Field

[0001] This utility model relates to the field of chemical equipment technology, specifically to a methyl ethyl carbonate reaction device with a vacuum negative pressure system. Background Technology

[0002] With the development of chemical, biopharmaceutical, and new materials fields, material reaction equipment has become a core device in the production process. However, existing equipment, when handling volatile or heat-sensitive materials, suffers from limited reaction efficiency and difficulty in achieving product purity standards due to the lack of effective pressure regulation methods. While patent CN116832760B improves gas utilization, it focuses on closed-loop circulation of gaseous components and lacks an active vacuum negative pressure regulation device, limiting its applicability in processes requiring pressure reduction to accelerate solvent evaporation. Patent CN113813911A optimizes the heat exchange process, but the lack of a dedicated negative pressure suction module and vacuum sealing system results in incomplete extraction of volatile components, making it difficult to meet the low-temperature reaction requirements of heat-sensitive materials under negative pressure. Currently, most equipment on the market focuses on physical stirring and conventional temperature control, making it difficult to achieve precise and stable vacuum negative pressure control during the reaction process. Utility Model Content

[0003] To address the problems of large vacuum fluctuations in existing negative pressure reaction equipment and the need to break the system vacuum for condensate discharge, this invention provides a methyl ethyl carbonate reaction equipment with a vacuum negative pressure system, which achieves precise and stable negative pressure during the reaction process and continuous and smooth discharge of condensate under negative pressure.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A methyl ethyl carbonate (MEC) reaction apparatus with a vacuum negative pressure system includes a reaction vessel body, a support frame, a vacuum negative pressure control component, a stirring power component, and a volatilization recovery component. The reaction vessel body is fixed to the support frame by lugs. The reaction vessel body includes a vessel shell and an inner reaction chamber lined inside the vessel shell. A closed heat transfer oil circulation jacket is formed between the inner reaction chamber and the vessel shell. A vessel cover is connected to the top of the inner reaction chamber via a flange. The stirring power component is mounted on the vessel cover and includes a motor base fixed to the top of the vessel cover, a variable frequency motor mounted on the motor base, and a stirring spindle driven by the variable frequency motor and extending into the inner reaction chamber. The vacuum negative pressure control component includes a vacuum buffer tank, a vacuum pump, and an electromagnetic compressive strength control system. The system includes a regulating valve and a pressure transmitter. The vacuum buffer tank is connected to the reactor lid via a pipe. The vacuum pump is connected to the outlet of the vacuum buffer tank via a pipe. The electromagnetic proportional regulating valve is installed on the vacuum buffer tank. The pressure transmitter is installed on the side wall of the liner reaction vessel and is electrically connected to the electromagnetic proportional regulating valve. The volatile recovery assembly includes a primary condenser, a secondary condenser, a first collection tank, and a second collection tank. The inlet of the primary condenser is connected to the exhaust port on the reactor lid. The outlet of the primary condenser is connected to the inlet of the secondary condenser. The outlet of the secondary condenser is connected to the inlet of the vacuum buffer tank. The first collection tank is connected to the bottom of the primary condenser, and the second collection tank is connected to the bottom of the secondary condenser.

[0005] The above scheme provides a physical foundation for negative pressure stability and a graded recovery path for the reactor by forming a hardware closed loop consisting of a vacuum buffer tank, an electromagnetic proportional control valve, and a pressure transmitter, combined with a series structure of multi-stage condensers and collection tanks.

[0006] Preferably, a precision vacuum gauge is installed on the vacuum buffer tank; a one-way check valve is installed on the pipeline between the vacuum pump and the vacuum buffer tank; and the sensor head of the pressure transmitter extends into the inner cavity of the liner reaction vessel.

[0007] This preferred solution provides local visual monitoring through a precision vacuum gauge, prevents backflow of the medium when the pump stops through a one-way check valve, and ensures that the pressure transmitter sensor head extends directly into the inner cavity to ensure that the pressure sampling accurately reflects the state of the reaction space, thereby enhancing the reliability and response accuracy of the vacuum control loop.

[0008] Preferably, the inlet of the primary condenser is connected to the exhaust port on the vessel lid, the bottom liquid phase outlet of the primary condenser is connected to the first collection tank, the outlet of the primary condenser is connected to the inlet of the secondary condenser through a pipe, the bottom liquid phase outlet of the secondary condenser is connected to the second collection tank, and both the primary and secondary condensers are equipped with spiral tube heat exchangers.

[0009] This preferred solution utilizes a structure with two-stage condensers connected in series and an internal spiral tube heat exchanger to achieve gradient condensation of volatile components using cooling media at different temperature levels. This improves the separation efficiency of high-boiling-point and low-boiling-point components. At the same time, the spiral tube structure increases the heat exchange area and enhances the condensation effect.

[0010] Preferably, the top of both the first and second collection tanks is provided with a balance branch pipe, which is connected to the gas phase space of the first-stage condenser and the second-stage condenser respectively; the bottom of both the first and second collection tanks is equipped with a discharge ball valve, and a vacuum breaker valve is provided below the discharge ball valve.

[0011] This preferred solution connects the top of the collection tank to the corresponding condenser's vapor phase space via a balanced branch pipe, ensuring that the internal pressure of the collection tank is consistent with that of the condenser, thus eliminating gas resistance during drainage. Combined with the bottom vacuum breaker valve, drainage can be completed by only relieving the local negative pressure in the collection tank, avoiding interference with the vacuum environment of the main reactor body, and achieving continuous online discharge of condensate.

[0012] Preferably, the stirring spindle has two sets of stirring blades fixed on its shaft inside the inner liner of the reaction vessel. The upper stirring blade is a three-bladed swept blade, and the lower stirring blade is a downward-sloping blade. A polytetrafluoroethylene scraper is connected to the side of the stirring spindle, and the polytetrafluoroethylene scraper is pressed against the inner wall of the inner liner of the reaction vessel by a spring compensation structure. A baffle structure is installed on the inner wall of the inner liner of the reaction vessel, and the baffle structure consists of multiple vertical plates evenly distributed along the circumference.

[0013] This preferred solution uses upper and lower combined blades to form an axial and radial composite flow field, which, together with a spring-pressed PTFE scraper, continuously removes the wall adhesion layer, effectively destroying the heat transfer boundary layer; the inner wall baffle structure inhibits vortex formation, enhances the uniformity of material mixing, and prevents heat-sensitive materials from overheating and charring due to local retention.

[0014] Preferably, the heat transfer oil circulation jacket is provided with spirally distributed guide plates inside; a pneumatic bottom valve is installed at the bottom center of the inner lining reaction vessel, and the top of the valve core of the pneumatic bottom valve is flush with the inner bottom surface of the inner lining reaction vessel.

[0015] This preferred design forces the heat transfer oil to flow spirally along the jacket through a spiral guide plate, extending the heat transfer medium's travel distance and increasing the flow rate, eliminating heat exchange dead zones, and making the reactor wall more uniformly heated; the zero-dead-angle structure of the pneumatic reactor bottom valve core, with the top of the valve core flush with the inner bottom surface, avoids the accumulation and residue of materials at the discharge port, ensuring the complete discharge of batch materials and product purity.

[0016] Preferably, a rubber sealing strip is installed on the inner wall of the vessel lid; the exhaust end of the vacuum pump is connected to a tail gas purification column, and the tail gas purification column is filled with activated carbon fiber felt.

[0017] This preferred solution enhances the static sealing performance of the reactor lid under negative pressure conditions by using a rubber sealing strip to prevent external air from seeping in; the activated carbon fiber felt in the exhaust gas purification column adsorbs and retains the trace amounts of volatile organic compounds remaining after secondary condensation, ensuring that the emitted gas meets environmental protection requirements and improving the system's sealing and environmental protection functions.

[0018] Beneficial effects This invention utilizes a hardware pressure stabilization circuit comprised of a vacuum buffer tank, an electromagnetic proportional control valve, and a pressure transmitter. The volumetric buffer of the vacuum tank helps to smooth fluctuations in the vacuum pump's pumping speed, while the pressure transmitter provides real-time feedback of the internal pressure signal to the electromagnetic proportional control valve. Changes in the valve opening adjust the compensation gas flow, thus achieving dynamic, precise, and stable vacuum within the reactor at the physical structural level. This provides a reliable low-temperature, low-pressure reaction environment for heat-sensitive materials. Simultaneously, a multi-stage volatile recovery assembly consisting of a primary condenser, a secondary condenser, and corresponding collection tanks, combined with a structural design that connects the top of the collection tank to the condenser's gas phase space and includes a vacuum breaker valve at the bottom, allows condensate discharge to occur only by partially breaking the negative pressure in the collection tank without affecting the vacuum state of the reactor body. This improves the fractional recovery rate of volatile components and ensures the continuity of the production process. In addition, the combined action of the impeller and spring-pressed scraper on the stirring shaft, along with the spiral guide plate in the jacket and the zero-dead-angle pneumatic bottom valve, further enhances the heat transfer uniformity and material discharge capacity, effectively preventing local overheating and residual contamination of the material, and comprehensively improving the operational stability and product quality of the methyl ethyl carbonate reaction equipment. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model.

[0020] Among them, 1-reaction vessel body, 2-support frame, 3-vacuum buffer tank, 4-precision vacuum gauge, 5-electromagnetic proportional regulating valve, 6-vacuum pump, 7-pressure transmitter, 8-first stage condenser, 9-second stage condenser, 10-first collection tank, 11-second collection tank, 12-stirring main shaft, 13-pneumatic bottom valve. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0023] Example 1 like Figure 1 As shown, this embodiment provides a methyl ethyl carbonate reaction device with a vacuum negative pressure system. The device includes a reactor body 1, a support frame 2, a vacuum negative pressure control component, a stirring power component, and a volatilization recovery component. The reactor body 1 is fixed to the support frame 2 by lugs, and the support frame 2 provides a stable load-bearing foundation for the entire reaction system. Specifically, the reactor body 1 adopts a multi-layer composite structure, including an outer shell and an inner liner reaction chamber located inside the outer shell. A closed heat transfer oil circulation jacket is formed between the inner liner reaction chamber and the outer shell. In actual manufacturing, the inner liner reaction chamber is preferably made of SUS316L stainless steel with excellent corrosion resistance, and its inner surface is finely polished to reduce material adhesion to the wall. The heat transfer oil circulation jacket is equipped with spirally distributed guide plates inside. These guide plates can force the heat transfer oil to flow along a spiral path within the jacket, significantly increasing the contact stroke and flow rate between the heat medium and the outer wall of the inner liner reaction chamber, effectively eliminating the heat exchange dead zone that is prone to occur in traditional jackets, and ensuring uniform heating of the reactor wall. The top of the inner reaction vessel is connected to the vessel lid via a flange. The inner wall of the vessel lid is fitted with a rubber sealing strip, such as a high-temperature resistant fluororubber sealing ring, to ensure tightness under high vacuum negative pressure and prevent external air from seeping in and interfering with the reaction environment.

[0024] The stirring power assembly is mounted on the vessel lid, including a motor mount fixed to the top of the lid, a variable frequency motor mounted on the motor mount, and a stirring shaft 12 driven by the variable frequency motor and extending into the inner liner of the reaction vessel. To enhance the mixing effect and prevent local overheating of heat-sensitive materials, two sets of stirring blades are fixed to the shaft inside the inner liner of the stirring shaft 12. The upper stirring blade is a three-bladed swept blade, which generates a strong downward axial flow when rotating, causing the material to tumble up and down. The lower stirring blade is a downward-sloping blade, mainly used to enhance the circulation flow at the bottom. In addition, a polytetrafluoroethylene (PTFE) scraper is connected to the side of the stirring shaft 12. The PTFE scraper is pressed against the inner wall of the inner liner of the reaction vessel by a spring compensation structure. As the shaft rotates, the scraper remains in close contact with the wall under the spring thrust, mechanically scraping off the adhering material and disrupting the heat transfer boundary layer. The inner wall of the liner reaction chamber is also equipped with a baffle structure, which consists of multiple vertical plates evenly distributed along the circumference. This baffle structure is used to suppress stirring vortices and enhance the radial mixing efficiency of materials.

[0025] The vacuum negative pressure control component is the core hardware circuit for achieving precise pressure regulation, including a vacuum buffer tank 3, a vacuum pump 6, an electromagnetic proportional control valve 5, and a pressure transmitter 7. The vacuum buffer tank 3 is connected to the gas phase outlet on the reactor lid via a pipe, the vacuum pump 6 is connected to the outlet of the vacuum buffer tank 3 via a pipe, the electromagnetic proportional control valve 5 is mounted on the vacuum buffer tank 3, and the pressure transmitter 7 is mounted on the side wall of the inner liner of the reaction vessel. Specifically, the sensor head of the pressure transmitter 7 extends directly into the inner cavity of the inner liner of the reaction vessel to acquire the absolute pressure signal of the reaction space in real time; the pressure transmitter 7 is electrically connected to the electromagnetic proportional control valve 5, which refers to a feedback path formed by physical signal cables, allowing the pressure signal to directly drive the valve. A precision vacuum gauge 4 is also installed on the vacuum buffer tank 3 for local visual monitoring; a one-way check valve is installed on the pipe between the vacuum pump 6 and the vacuum buffer tank 3 to prevent backflow of the medium when the pump stops. It should be understood that although the figure shows the electromagnetic proportional regulating valve 5 installed on the top of the buffer tank, in other embodiments, the same pressure stabilization function can be achieved as long as it is connected in series in the gas supply passage or the gas extraction line and its opening can be controlled and adjusted.

[0026] The evaporation recovery assembly includes a primary condenser 8, a secondary condenser 9, a first collection tank 10, and a second collection tank 11. The inlet of the primary condenser 8 is connected to the exhaust port on the vessel lid, and the outlet of the primary condenser 8 is connected to the inlet of the secondary condenser 9 via a pipe. The outlet of the secondary condenser 9 is connected to the inlet of the vacuum buffer tank 3, thus forming a multi-stage gradient condensation recovery path. Both the primary condenser 8 and the secondary condenser 9 are equipped with spiral tube heat exchangers. Compared to ordinary tube heat exchangers, the spiral tube structure increases the heat exchange area and enhances turbulence. The first collection tank 10 is connected to the bottom of the primary condenser 8, and the second collection tank 11 is connected to the bottom of the secondary condenser 9. To ensure smooth drainage under negative pressure without disrupting the vacuum of the main system, the tops of both the first collection tank 10 and the second collection tank 11 are equipped with balancing branch pipes. These branch pipes are connected to the gas phase spaces of the primary condenser 8 and the secondary condenser 9, respectively, so that the pressure inside the collection tank is consistent with that of the condenser, eliminating gas resistance during drainage. At the same time, the bottoms of both the first collection tank 10 and the second collection tank 11 are equipped with discharge ball valves, and a vacuum breaking valve is installed below the discharge ball valves. During drainage, the negative pressure can be broken only locally in the collection tank without affecting the vacuum environment inside the reactor body 1.

[0027] Regarding material discharge and exhaust gas treatment, a pneumatic bottom valve 13 is installed at the center of the bottom of the inner reactor vessel. The top of the valve core of the pneumatic bottom valve 13 is flush with the inner bottom surface of the inner reactor vessel. This zero-dead-angle design ensures that the valve core is completely coplanar with the bottom of the vessel when closed, preventing material accumulation and residue at the discharge port and ensuring complete discharge of batches of material. The exhaust end of the vacuum pump 6 is connected to an exhaust gas purification column, which is filled with activated carbon fiber felt to adsorb trace amounts of volatile organic compounds remaining after secondary condensation, ensuring that emissions meet standards. Through the coordinated operation of the above components, this embodiment constructs a complete reaction system integrating precise negative pressure control, efficient staged condensation and recovery, uniform stirring and heat exchange, and zero-dead-angle material discharge.

[0028] Example 2 This embodiment, based on the methyl ethyl carbonate reaction equipment with a vacuum negative pressure system provided in Embodiment 1, takes the methyl ethyl carbonate synthesis process as an example to further illustrate the operating principle and working process of this equipment in actual production. This operating process fully utilizes the hardware synergy between various components, achieving precise control throughout the entire process from sealing initialization to finished product unloading.

[0029] Step S100, initial sealing. After feeding, the operator closes the reactor lid and tightens the bolts to ensure the rubber sealing strip installed on the inner wall of the lid is firmly pressed against the sealing surface. The elastic deformation of the rubber material fills the microscopic gaps, thus establishing a reliable static sealing barrier at the top of the reactor body 1. Simultaneously, it is confirmed that the pneumatic bottom valve 13 is closed, and the discharge ball valves and vacuum breaker valves at the bottom of the first collection tank 10 and the second collection tank 11 are checked to ensure the entire system is in a sealed, vacuum-ready state. This step is fundamental for establishing a stable negative pressure environment. Compared to traditional metal gaskets, the rubber sealing strip is better able to adapt to the minute deformations under negative pressure conditions, effectively preventing external air infiltration.

[0030] Step S200: Establish negative pressure. Start vacuum pump 6. The gas inside the system sequentially passes through the exhaust port on the reactor lid, the primary condenser 8, and the secondary condenser 9, finally entering the vacuum buffer tank 3 and being extracted, forming a complete circulating gas extraction path. During this process, the pressure transmitter 7, installed on the side wall of the reaction tank liner, monitors the absolute pressure inside the cavity in real time and feeds back the pressure signal to the electromagnetic proportional control valve 5 via a physical cable. When the vacuum inside the reactor is detected to be too high (i.e., the pressure is lower than the set value), the electromagnetic proportional control valve 5 automatically opens slightly, introducing filtered external air into the vacuum buffer tank 3 for pressure compensation; conversely, it reduces the opening. This hardware-based closed-loop dynamic adjustment mechanism effectively counteracts pressure changes caused by violent material evaporation or pump speed fluctuations, maintaining the negative pressure inside the reactor within a very narrow fluctuation range. Furthermore, the one-way check valve installed on the pipeline between vacuum pump 6 and vacuum buffer tank 3 immediately cuts off the pipeline in the event of an unexpected pump stop, preventing pump oil or air from being drawn back into the reaction system, ensuring process safety.

[0031] Step S300: Heating and stirring reaction. High-temperature heat transfer oil is introduced into the heat transfer oil circulation jacket. The spiral distribution guide plates welded inside the jacket force the heat transfer oil to flow spirally upward along the reactor wall, significantly extending the residence time of the heat medium and increasing the flow rate. This completely eliminates the heat exchange dead zone that is prone to occur in traditional jackets, ensuring uniform heating of the inner lining reaction vessel. At the same time, the variable frequency motor drives the stirring shaft 12 to rotate. The three-bladed swept-back impeller at the top generates a strong downward axial flow, causing the material to tumble up and down; the downward-sloping impeller at the bottom enhances bottom circulation. Together, they form a highly efficient composite stirring flow field. In particular, the PTFE scraper on the side of the stirring shaft 12, under the continuous thrust of the spring compensation structure, always rotates close to the inner wall, mechanically scraping away high-viscosity materials or scale layers adhering to the wall surface, constantly renewing the heat transfer boundary layer, and preventing the heat-sensitive methyl ethyl carbonate from decomposing or coking due to local overheating. The vertical baffle structure evenly distributed circumferentially on the inner wall of the liner reactor effectively suppresses the generation of stirring vortices and further enhances the radial mixing efficiency of materials.

[0032] Step S400: Volatile Gas Condensation and Recovery. The volatile gases produced in the reaction enter the volatile recovery assembly under negative pressure. The gases first exchange heat with the cooling medium in the primary condenser 8, where most of the high-boiling-point components are initially condensed and flow into the first collection tank 10; the uncondensed low-boiling-point components continue to the secondary condenser 9 for further condensation, and after liquefaction, flow into the second collection tank 11. The spiral tube heat exchangers installed inside both condensers significantly increase the heat exchange area and improve condensation efficiency. To ensure smooth drainage under negative pressure, the balance branch pipes at the top of the first collection tank 10 and the second collection tank 11 are connected to the gas phase space of the corresponding condensers, ensuring real-time pressure balance inside and outside the collection tanks and eliminating gas resistance during gravity drainage. When condensate needs to be discharged, the operator first closes the collection tank inlet valve, then opens the vacuum breaking valve at the bottom to partially break the negative pressure in the collection tank, and finally opens the discharge ball valve to drain the liquid. This design makes the drainage operation completely independent of the main reaction system, without affecting the vacuum level inside the reactor body 1, thus achieving continuous production.

[0033] Step S500, unloading. After the reaction is complete and atmospheric pressure is restored, open the pneumatic bottom valve 13 installed at the center of the bottom of the reactor. Because the top of the valve core is flush with the inner bottom surface of the reaction vessel liner, there are no grooves or steps at the discharge port, and the material can be completely discharged under gravity without any residue accumulation. This zero-dead-angle design is crucial for the production of high-purity methyl ethyl carbonate, avoiding cross-contamination between batches and the risk of long-term heat-induced deterioration of residual materials.

[0034] Step S600, exhaust gas treatment. Throughout the vacuuming and reaction process, the exhaust gas purification column connected to the exhaust end of vacuum pump 6 operates continuously. The activated carbon fiber felt inside the column efficiently adsorbs and retains any trace amounts of organic vapor that may remain after secondary condensation, ensuring that the final emitted gas meets environmental standards. It should be understood that although this embodiment uses the synthesis of methyl ethyl carbonate as an example, the operating logic of this equipment is also applicable to other chemical scenarios that require the reaction of thermosensitive materials and solvent recovery under precise negative pressure.

[0035] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A reaction apparatus for methyl ethyl carbonate with a vacuum negative pressure system, characterized in that, It includes the reactor body (1), support frame (2), vacuum negative pressure control assembly, stirring power assembly and volatilization recovery assembly; The reactor body (1) is fixed to the support frame (2) by means of lugs; the reactor body (1) includes a reactor shell and an inner liner reaction chamber disposed inside the reactor shell; a closed heat transfer oil circulation jacket is formed between the inner liner reaction chamber and the reactor shell; the top of the inner liner reaction chamber is connected to the reactor cover by a flange; The stirring power assembly is installed on the vessel cover. The stirring power assembly includes a motor base fixed to the top of the vessel cover, a variable frequency motor installed on the motor base, and a stirring spindle (12) driven by the variable frequency motor and extending into the interior of the liner reaction chamber. The vacuum negative pressure control assembly includes a vacuum buffer tank (3), a vacuum pump (6), an electromagnetic proportional regulating valve (5), and a pressure transmitter (7). The vacuum buffer tank (3) is connected to the vessel cover via a pipe. The vacuum pump (6) is connected to the outlet end of the vacuum buffer tank (3) via a pipe. The electromagnetic proportional regulating valve (5) is installed on the vacuum buffer tank (3). The pressure transmitter (7) is installed on the side wall of the inner lining reaction vessel. The pressure transmitter (7) is electrically connected to the electromagnetic proportional regulating valve (5). The volatile recovery assembly includes a primary condenser (8), a secondary condenser (9), a first collection tank (10), and a second collection tank (11). The inlet of the primary condenser (8) is connected to the exhaust port on the vessel lid, the outlet of the primary condenser (8) is connected to the inlet of the secondary condenser (9), and the outlet of the secondary condenser (9) is connected to the inlet of the vacuum buffer tank (3). The first collection tank (10) is connected to the bottom of the primary condenser (8), and the second collection tank (11) is connected to the bottom of the secondary condenser (9).

2. The methyl ethyl carbonate reaction apparatus with a vacuum negative pressure system according to claim 1, characterized in that, A precision vacuum gauge (4) is installed on the vacuum buffer tank (3); a one-way check valve is installed on the pipeline between the vacuum pump (6) and the vacuum buffer tank (3); the sensing head of the pressure transmitter (7) extends into the inner cavity of the liner reaction chamber.

3. The methyl ethyl carbonate reaction apparatus with a vacuum negative pressure system according to claim 1, characterized in that, The inlet of the first-stage condenser (8) is connected to the exhaust port on the vessel lid. The bottom liquid phase outlet of the first-stage condenser (8) is connected to the first collection tank (10). The outlet of the first-stage condenser (8) is connected to the inlet of the second-stage condenser (9) through a pipe. The bottom liquid phase outlet of the second-stage condenser (9) is connected to the second collection tank (11). Both the first-stage condenser (8) and the second-stage condenser (9) are equipped with spiral tube heat exchangers.

4. The methyl ethyl carbonate reaction apparatus with a vacuum negative pressure system according to claim 3, characterized in that, The top of the first collection tank (10) and the second collection tank (11) are provided with balance branch pipes, which are respectively connected to the gas phase space of the first-stage condenser (8) and the second-stage condenser (9); the bottom of the first collection tank (10) and the second collection tank (11) are both equipped with discharge ball valves, and a vacuum breaking valve is provided below the discharge ball valves.

5. The methyl ethyl carbonate reaction apparatus with a vacuum negative pressure system according to claim 1, characterized in that, The stirring shaft (12) has two sets of stirring blades fixed on its shaft inside the inner liner of the reaction chamber. The upper stirring blade is a three-bladed swept blade, and the lower stirring blade is a downward-sloping blade. A polytetrafluoroethylene scraper is connected to the side of the stirring shaft (12). The polytetrafluoroethylene scraper is pressed against the inner wall of the inner liner of the reaction chamber by a spring compensation structure. A baffle structure is installed on the inner wall of the inner liner of the reaction chamber. The baffle structure consists of multiple vertical plates evenly distributed along the circumference.

6. The methyl ethyl carbonate reaction apparatus with a vacuum negative pressure system according to claim 1, characterized in that, The heat transfer oil circulation jacket is provided with spirally distributed guide plates inside; a pneumatic bottom valve (13) is installed at the bottom center of the inner lining reaction vessel, and the top of the valve core of the pneumatic bottom valve (13) is flush with the inner bottom surface of the inner lining reaction vessel.

7. The methyl ethyl carbonate reaction apparatus with a vacuum negative pressure system according to claim 1, characterized in that, The inner wall of the vessel lid is fitted with a rubber sealing strip; the exhaust end of the vacuum pump (6) is connected to a tail gas purification column, which is filled with activated carbon fiber felt.

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