A flare gas incineration treatment system and method for EVA production

Abstract

This invention belongs to the field of waste gas treatment technology, specifically disclosing a flare gas incineration treatment system for EVA production. The system includes a daily gas buffer tank and an emergency gas buffer tank, each connected in series with a liquid separator, a water seal tank, and a cooler. The gas outlets of the two coolers are connected to an incinerator, and the flue gas outlet of the incinerator is connected in series with an induced draft fan and a chimney. Addressing the safety risks, such as explosions, posed by direct combustion of flare gas generated during EVA production, this invention achieves safe, efficient, and compliant emissions of flare gas by classifying and collecting the flare gas, separating it into liquids, applying a water seal, pre-treating it with cooling, and precisely monitoring key parameters, combined with efficient incineration in an incinerator. This solves the problem that direct combustion of flare gas containing hydrocarbons such as ethylene, vinyl acetate, and organic solvents generated during EVA production can easily lead to explosions or flameout accidents due to gas composition imbalance.

Description

Technical Field

[0001] This invention relates to the field of waste gas treatment technology, specifically to a flare gas incineration treatment system and method for EVA production. Background Technology

[0002] Ethylene-vinyl acetate copolymer (EVA), a high-performance thermoplastic polymer, is widely used in photovoltaic encapsulation films, wire and cable insulation layers, hot melt adhesives, and foaming materials due to its excellent flexibility, impact resistance, weather resistance, and compatibility with other materials. EVA production primarily employs a high-pressure bulk polymerization process, requiring high temperatures of 150℃-250℃ and high pressures of 100MPa-300MPa. Ethylene is the main monomer, and vinyl acetate is the comonomer, with the polymerization reaction completed in a reactor under the action of an initiator. This process involves multiple stages of material handling, reaction control, and product separation. Specific steps include: raw material pretreatment, high-pressure polymerization reaction, depressurization and separation of reaction products, melt granulation, and finished product storage. Due to the high-pressure characteristics of the process, the volatility of the materials, and the need for dynamic adjustments in the production process, volatile gases containing hydrocarbons, i.e., flare gases, are inevitably generated during EVA production. Direct emission of these flare gases not only pollutes the environment but also poses safety risks such as explosions and poisoning, thus becoming a key issue restricting the environmental friendliness and safety of EVA production.

[0003] During EVA production, flare gas containing hydrocarbons such as ethylene, vinyl acetate, and organic solvents is generated in various stages, including raw material pretreatment, polymerization reaction, product separation and purification, unit start-up and shutdown, and handling of abnormal operating conditions. This flare gas can be categorized into routine emissions and emergency emissions. Raw material purity is crucial for ensuring the stability of the EVA polymerization reaction and the quality of the product. Therefore, ethylene, VAM, and auxiliary raw materials, such as initiators and molecular weight regulators, must undergo pretreatment to remove impurities before entering the polymerization system. This process results in the emission of light component gases, forming flare gas. Emergency shutdowns of EVA production units involve system pressure adjustments, material replacement, and emergency pressure relief in case of abnormal operating conditions such as equipment failure. These emergency shutdowns can instantly generate large amounts of flammable gas, becoming a sudden source of flare gas.

[0004] Current technologies typically involve mixing and recovering routine and emergency emissions before incineration. However, because routine emissions are small and stable, while emergency emissions are large and intense, fluctuations in gas volume and composition can easily lead to incomplete combustion, generating pollutants such as VOCs and black smoke. Furthermore, low-concentration flare gas entering the flare system can easily cause flameout, resulting in the direct emission of unburned hydrocarbons, polluting the environment and posing safety risks. Therefore, to address these issues, it is necessary to design a flare gas incineration and treatment system and method for EVA production. This system aims to solve the problem that flare gas containing hydrocarbons such as ethylene, vinyl acetate, and organic solvents generated during EVA production, when directly entering the incinerator, can easily lead to explosions or flameouts due to gas composition imbalances. Summary of the Invention

[0005] The purpose of this invention is to provide a flare gas incineration treatment system and method for EVA production, in order to solve the problem that flare gas containing hydrocarbons such as ethylene, vinyl acetate and organic solvents generated during the EVA production process is prone to explosion or flameout due to gas composition imbalance when directly entering the incinerator.

[0006] To achieve the above objectives, the basic solution provided by this invention is as follows: a flare gas incineration treatment system for EVA production, comprising a daily gas buffer tank, an emergency gas buffer tank, and a PLC controller. The daily gas buffer tank is connected to a reactor and a raw material storage tank. A daily gas inlet valve is provided on the pipeline connecting the daily gas buffer tank and the reactor. The emergency gas buffer tank is provided with an emergency gas inlet valve, an emergency shut-off valve, and a pressure safety valve. Gas-liquid separation components are provided at the gas outlets of both the daily gas buffer tank and the emergency gas buffer tank. Daily gas outlet valves and emergency gas outlet valves are respectively provided on the pipelines connecting the daily gas buffer tank and the emergency gas buffer tank to the gas-liquid separation components. A daily gas cooler and an emergency gas cooler are connected to the gas-liquid separation components. A water seal outlet valve is provided on the pipelines connecting the gas-liquid separation components to the daily gas cooler and the emergency gas cooler. A venting component is connected to the gas outlets of the daily gas cooler and the emergency gas cooler.

[0007] The beneficial effects of the present invention are as follows: (1) The present invention sets up independent buffer tanks, liquid separators, water seal tanks and coolers for the low-pressure, small-flow flare gas continuously discharged daily and the high-pressure, large-flow flare gas instantaneously discharged in the event of an accident, and sets different process parameters according to the characteristics of the two types of flare gas, thereby avoiding the impact of the accident gas on the daily treatment system, ensuring the relative stability of the incinerator's gas flow rate and composition, and solving the problem of incomplete combustion and black smoke caused by drastic fluctuations in gas volume and composition; at the same time, the high-pressure accident gas passage adopts a high-pressure alloy pipeline, which reduces the risk of overpressure and leakage; (2) Through the pretreatment process of separation, water sealing and cooling, the condensation and separation of vinyl acetate with a boiling point of 72.5℃ in EVA production was effectively achieved; the incinerator adopts a heat storage body to preheat the air intake, which improves the thermal efficiency. At the same time, the waste heat boiler connected to the back end of the incinerator generates steam, realizing energy utilization and reducing the operating cost of the entire treatment facility; (3) the risk of explosive mixture formation and flameout is eliminated by the dual interlocking of oxygen content and hydrocarbon content detection. At the same time, the hydrocarbon concentration is maintained in the range of 25%LEL-50%LEL, ensuring the effectiveness of combustion temperature and time, so that the emission concentration of VOCs is ≤20mg / m³. 3 .

[0008] Option 2, which is a preferred option of the basic option, includes a liquid separator, a raw material recovery system connected to the liquid outlet of the liquid separator, a water seal tank connected to the gas outlet of the liquid separator, an overflow pipe and a water supply valve at the top of the water seal tank, and a water seal inlet valve on the pipeline connecting the liquid separator and the water seal tank.

[0009] Option 3, which is a preferred option of the basic option, is provided with several layers of baffles in both the daily gas-liquid separator and the emergency gas-liquid separator. The baffles are tilted at an angle of 30°. The baffles increase the gas-liquid contact area, which can improve the removal rate of liquid impurities.

[0010] Option 4, a preferred option of the basic option, includes a check valve on the pipeline connecting the daily gas buffer tank and the reactor. Both the daily gas separator and the emergency gas separator are equipped with level gauges and drain valves at their bottoms. The level gauges and drain valves are electrically connected, and the drain valves are electrically connected to the PLC controller. The level gauges allow for real-time monitoring of the liquid levels in the daily gas separator and the emergency gas separator, preventing excessively high liquid levels that could cause liquid to enter the gas phase pipeline and affect combustion stability.

[0011] Option 5, a preferred embodiment of the basic option, includes an incinerator as the venting component. The incinerator is connected to a daily gas cooler and an emergency gas cooler via pipelines, respectively equipped with daily gas discharge valves and emergency gas discharge valves. An oxygen analyzer, a hydrocarbon analyzer, and a mixed flare gas inlet valve are connected in series on the pipelines where the daily gas cooler, emergency gas cooler, and incinerator intersect. The pipeline before the mixed flare gas inlet valve is connected to an emergency gas buffer tank and equipped with a flare gas bypass valve. A nitrogen purging pipeline is provided on the pipelines connecting the daily gas cooler, emergency gas cooler, and incinerator, with a nitrogen purging valve on the nitrogen purging pipeline. An induced draft fan is provided at the incinerator flue gas outlet, and the outlet of the induced draft fan is connected to a chimney. A mixed flare gas discharge valve is provided on the pipeline connecting the induced draft fan and the chimney.

[0012] Option 6, a method for treating flare gas combustion in EVA production, includes the following steps: S1: Daily Gas Collection: When it is necessary to collect the flare gas generated during EVA production, the operator first opens the daily gas inlet valve and check valve sequentially via the PLC controller, allowing the flare gas generated in the reactor and raw material storage tank to enter the daily gas buffer tank to stabilize the flare gas pressure and flow rate fluctuations; the flow rate of the flare gas generated in the reactor and raw material storage tank is 50m³ / h. 3 / h-500m 3 / h, pressure is 0.1MPa-0.3MPa, and the pressure inside the daily gas buffer tank is 0.15MPa-0.25MPa; S2: Emergency Gas Collection: In the event of equipment overpressure or malfunction requiring emergency shutdown during EVA production, first open the emergency gas inlet valve to release the pressure from the equipment. The resulting flow rate is 1000 m³ / s. 3 / h-5000m 3 Flare gas with a pressure of 1.0MPa-2.0MPa is introduced into the emergency gas buffer tank at a rate of 1.0MPa-2.0MPa per hour to stabilize the pressure and flow rate of the flare gas. S3: Liquid Separation Processing: Then, the PLC controller opens the daily gas outlet valve and the emergency gas outlet valve to introduce the flare gas from the daily gas buffer tank and the emergency gas buffer tank into the daily gas liquid separator and the emergency gas liquid separator, respectively, for gas-liquid separation, so that the liquid hydrocarbons, condensate and vinyl acetate precipitate in the flare gas are separated; then, the water seal inlet valve A and the water seal inlet valve B are opened to introduce the liquid-separated flare gas into the water seal tank A and the water seal tank B, respectively, to further intercept the liquid in the flare gas. S4: Cooling treatment: Then open the water seal outlet valve A and water seal outlet valve B to discharge the flare gas after liquid separation into the daily gas cooler and the emergency gas cooler for cooling, so that the vinyl acetate in the flare gas can be further condensed and separated. S5: Incineration treatment: Finally, open the daily gas discharge valve, emergency gas discharge valve, mixed flare gas inlet valve and mixed flare gas discharge valve in sequence to discharge the cooled flare gas into the incinerator for combustion. The combustion temperature in the incinerator is 900℃-1200℃. The residence time of the flare gas in the incinerator is ≥2.5s. Then, it is discharged into the chimney through the induced draft fan.

[0013] Option 7, which is the preferred option of Option 6, in S3, the water seal height of the normal gas is 0.8m-1.2m, and the water seal height of the emergency gas is 2.0m-2.5m; to ensure the sealing reliability under different working conditions.

[0014] Option 8, which is the preferred option of Option 6, is that in S4, the temperature of the flare gas after being cooled by the daily gas cooler and the emergency gas cooler is 20℃-30℃. The low temperature can promote the further condensation and separation of vinyl acetate, reduce the combustion load, and at the same time prevent high-temperature gas from damaging the internal structure of the incinerator.

[0015] Option 9, which is a preferred option of Option 6, involves the following steps in S5: When the flare gas passes through the oxygen analyzer, the analyzer detects the oxygen content in the flare gas. If the oxygen content analyzer detects an oxygen content ≥4 vol%, the PLC controller closes the mixed flare gas inlet valve and simultaneously opens the nitrogen purge valve to replace the gas in the pipeline until the oxygen content in the pipeline is ≤1 vol%. Then, the mixed flare gas inlet valve is opened to allow the flare gas to be introduced into the incinerator for combustion.

[0016] Option 10, an optimal choice of Option 6, involves a hydrocarbon content analyzer monitoring the hydrocarbon content in the flare gas in real time before it enters the incinerator in S5. If the hydrocarbon content is ≤15%LEL, natural gas is introduced into the pipeline to maintain the hydrocarbon content in the flare gas between 25%LEL and 50%LEL. If the hydrocarbon content is ≥90%LEL, the flare gas bypass valve is opened via the PLC controller to discharge some of the flare gas into the emergency gas buffer tank until the hydrocarbon content in the flare gas is between 25%LEL and 50%LEL. This ensures stable calorific value of the flare gas and continuous operation of the incinerator. When the hydrocarbon content is too low, natural gas is used to assist combustion; when the hydrocarbon content is too high, the bypass valve is used to reduce the hydrocarbon content in the flare gas, preventing flameout or incomplete combustion. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a flare gas incineration treatment system for EVA production according to the present invention.

[0018] The reference numerals in the accompanying drawings of this instruction manual include: 1. Normal gas buffer tank; 2. Emergency gas buffer tank; 3. Reactor; 4. Raw material storage tank; 5. Normal gas inlet valve; 6. Emergency gas inlet valve; 7. Emergency shut-off valve; 8. Pressure safety valve; 9. Normal gas outlet valve; 10. Emergency gas outlet valve; 11. Normal gas cooler; 12. Emergency gas cooler; 13. Water seal outlet valve; 14. Incinerator; 15. Normal gas discharge valve; 16. Emergency gas discharge valve; 17. 18. Oxygen content analyzer; 19. Hydrocarbon content analyzer; 20. Mixed flare gas inlet valve; 21. Flare gas bypass valve; 22. Nitrogen purging pipeline; 23. Nitrogen purging valve; 24. Exhaust fan; 25. Chimney; 26. Mixed flare gas exhaust valve; 27. Separator; 28. Raw material recovery system; 29. ​​Water seal tank; 30. Overflow pipe; 31. Water supply valve; 32. Water seal inlet valve; 33. Baffle plate; 34. Check valve; 35. Level gauge; 36. Drain valve. Detailed Implementation

[0019] The present invention will be further described in detail below through specific embodiments: Example like Figure 1The diagram shows a flare gas incineration treatment system for EVA production, comprising a normal gas buffer tank 1, an emergency gas buffer tank 2, and a PLC controller. The normal gas buffer tank 1 is connected to a reactor 3 and a raw material storage tank 4. A check valve 33 and a normal gas inlet valve 5 are installed on the pipeline connecting the normal gas buffer tank 1 and the reactor 3. The emergency gas buffer tank 2 is equipped with an emergency gas inlet valve 6 and an emergency shut-off valve 7. A pressure relief valve 8 is installed at the top of the emergency gas buffer tank 2. Gas-liquid separation components are installed at the gas outlets of both the normal gas buffer tank 1 and the emergency gas buffer tank 2. Each gas-liquid separation component includes a separator 26, which contains a liquid separator. Several layers of baffles 32 are provided, with an inclination angle of 30°. The liquid outlet of the separator 26 is connected to a raw material recovery system 27, and the gas outlet of the separator 26 is connected to a water seal tank 28. The top of the water seal tank 28 is equipped with an overflow pipe 29 and a water supply valve 30. A water seal inlet valve 31 is provided on the pipeline connecting the separator 26 and the water seal tank 28. A level gauge 34 and a drain valve 35 are provided at the bottom of the separator 26. The level gauge 34 and the drain valve 35 are electrically connected, and the drain valve 35 is electrically connected to a PLC controller. Daily gas buffer tank 1 and emergency gas buffer tank 2 are respectively equipped with daily gas buffer systems on the pipelines connecting them to the separator 26. Normal gas outlet valve 9 and emergency gas outlet valve 10 are provided. Two water seal tanks 28 are respectively connected to a normal gas cooler 11 and an emergency gas cooler 12. Water seal outlet valves 13 are provided on the pipelines connecting the water seal tanks 28 to the normal gas coolers 11 and 12. Venting components, including an incinerator 14, are connected to the gas outlets of the normal gas coolers 11 and 12. Normal gas discharge valves 15 and 16 are respectively provided on the pipelines connecting the incinerator 14 to the normal gas coolers 11 and 12. The normal gas coolers 11 and 12 are connected to the incinerator... An oxygen content analyzer 17, a hydrocarbon content analyzer 18, and a mixed flare gas inlet valve 19 are connected in series on the pipeline where the incinerator 14 intersects. The pipeline before the mixed flare gas inlet valve 19 is connected to the emergency gas buffer tank 2 and is equipped with a flare gas bypass valve 20. A nitrogen purging pipeline 21 is provided on the pipeline connecting the normal gas cooler 11 and the emergency gas cooler 12 to the incinerator 14. A nitrogen purging valve 22 is provided on the nitrogen purging pipeline 21. An induced draft fan 23 is provided at the flue gas outlet of the incinerator 14. The outlet of the induced draft fan 23 is connected to the chimney 24. A mixed flare gas discharge valve 25 is provided on the pipeline connecting the induced draft fan 23 and the chimney 24.

[0020] Based on the above-mentioned EVA production flare gas incineration treatment system, a method for treating flare gas incineration during EVA production is provided, specifically including the following steps: S1: Daily Gas Collection: When it is necessary to collect the flare gas generated during EVA production, the operator first opens the daily gas inlet valve 5 and check valve 33 sequentially via the PLC controller. This allows the flare gas generated in reactor 3 and raw material storage tank 4 to enter the daily gas buffer tank 1, stabilizing the flare gas pressure and flow fluctuations. The flow rate of the flare gas generated in reactor 3 and raw material storage tank 4 is 50 m³ / s. 3 / h-500m 3 / h, pressure is 0.1MPa-0.3MPa, and the pressure in daily gas buffer tank 1 is 0.15MPa-0.25MPa; S2: Emergency Gas Collection: In the event of equipment overpressure or malfunction requiring emergency shutdown during EVA production, first open the emergency gas inlet valve 6 to introduce the flare gas generated during equipment depressurization into the emergency gas buffer tank 2. The emergency gas buffer tank 2 stabilizes the pressure and flow rate of the flare gas; the emergency gas flow rate is 1000 m³ / h. 3 / h-5000m 3 / h, pressure is 1.0MPa-2.0MPa; S3: Liquid Separation Processing: Then, the PLC controller opens the daily gas outlet valve 9 and the emergency gas outlet valve 10 to introduce the flare gas from the daily gas buffer tank 1 and the emergency gas buffer tank 2 into the liquid separators 26 for daily gas and emergency gas, respectively, to separate the liquid hydrocarbons, condensate, and vinyl acetate precipitate in the flare gas. Next, the water seal inlet valve 31 is opened to introduce the liquid-separated flare gas into the water seal tanks 28 for daily gas and emergency gas, respectively, to further intercept the liquid in the flare gas. The water seal height for daily gas is 0.8m-1.2m, and the water seal height for emergency gas is 2.0m-2.5m. S4: Cooling treatment: Next, open the water seal outlet valve 13 to allow the flare gas after separation to be discharged into the daily gas cooler 11 and the emergency gas cooler 12 respectively, cooling it from 40℃-80℃ to 20℃-30℃, so that the vinyl acetate in the flare gas can be further condensed and separated. S5: Incineration: Finally, open the daily gas vent valve 15, emergency gas vent valve 16, mixed flare gas inlet valve 19, and mixed flare gas vent valve 25 in sequence to discharge the cooled flare gas into the incinerator 14 for combustion. Before entering the incinerator 14, the flare gas passes through the oxygen content analyzer 17, which detects the oxygen content. If the oxygen content analyzer 17 detects an oxygen content ≥4 vol%, the mixed flare gas inlet valve 19 is closed via the PLC controller, and the nitrogen purging valve 22 is opened to replace the gas in the pipeline until the oxygen content in the pipeline is ≤1 vol%. Then, the hydrocarbon content of the flare gas is detected. If the hydrocarbon content is ≤15%LEL, natural gas is introduced into the pipeline to maintain the hydrocarbon content in the flare gas between 25%LEL and 50%LEL. L; If the hydrocarbon content is ≥90%LEL (%LEL is the lower explosive limit percentage unit, representing the percentage of the concentration of combustible gas in air relative to its lower explosive limit volume concentration), then the flare gas bypass valve 20 is opened through the PLC controller to discharge part of the flare gas into the emergency gas buffer tank 2 until the hydrocarbon content in the flare gas is between 25%LEL and 50%LEL. Then, the mixed flare gas inlet valve 19 is opened to allow the flare gas to be introduced into the incinerator 14 for combustion. The combustion temperature in the incinerator 14 is 900℃-1200℃, and the residence time of the flare gas in the incinerator 14 is ≥2.5s. The flue gas generated by the combustion of the flare gas in the incinerator 14 is then cooled by the waste heat boiler after heat recovery, cooled by the quench tower, and then the residual VOCs in the flue gas are removed by the activated carbon adsorption tower before being discharged into the chimney 24 by the induced draft fan 23.

[0021] In summary, by collecting daily and emergency gases through independent pipelines and buffer tanks using the above methods, the impact of gas volume fluctuations on the incineration system is avoided. Furthermore, multi-stage pretreatment of both daily and emergency gases deeply removes high-boiling-point components such as liquid hydrocarbons, condensate, and vinyl acetate, improving incineration stability by over 40% and preventing the emission of black smoke and incomplete combustion products. Simultaneously, it reduces carbon buildup and coking in the incinerator, extending the equipment maintenance cycle to over 6 months. Through precise control of incineration temperature and flue gas residence time in the incinerator, combined with deep flue gas treatment, the emission concentration of VOCs is ≤20 mg / m³. 3 The levels are far below national standards, achieving harmless treatment of flare gas.

[0022] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A flare gas incineration and treatment system for EVA production, characterized in that, The system includes a daily gas buffer tank (1), an emergency gas buffer tank (2), and a PLC controller. The daily gas buffer tank (1) is connected to a reactor (3) and a raw material storage tank (4). A daily gas inlet valve (5) is provided on the pipeline connecting the daily gas buffer tank (1) and the reactor (3). The emergency gas buffer tank (2) is provided with an emergency gas inlet valve (6), an emergency shut-off valve (7), and a pressure relief valve (8). Gas-liquid separation components are provided at the gas outlets of both the daily gas buffer tank (1) and the emergency gas buffer tank (2). The gas buffer tank (1) and the emergency gas buffer tank (2) are respectively provided with a gas outlet valve (9) and an emergency gas outlet valve (10) on the pipelines connecting them to the gas-liquid separation component. The gas-liquid separation component is connected to a gas cooler (11) and an emergency gas cooler (12). The gas-liquid separation component is provided with a water seal outlet valve (13) on the pipelines connecting it to the gas cooler (11) and the emergency gas cooler (12). The gas outlets of the gas cooler (11) and the emergency gas cooler (12) are connected to a venting component.

2. The flare gas incineration and treatment system for EVA production according to claim 1, characterized in that, The gas-liquid separation assembly includes a liquid separator (26), the liquid outlet of which is connected to a raw material recovery system (27), and the gas outlet of which is connected to a water seal tank (28). The top of the water seal tank (28) is provided with an overflow pipe (29) and a water supply valve (30), and a water seal inlet valve (31) is provided on the pipeline connecting the liquid separator (26) and the water seal tank (28).

3. A flare gas incineration and treatment system for EVA production according to claim 2, characterized in that, The separator (26) is provided with several layers of baffles (32), and the baffles (32) are inclined at an angle of 30°.

4. A flare gas incineration and treatment system for EVA production according to claim 2, characterized in that, A check valve (33) is provided on the pipeline connecting the daily gas buffer tank (1) and the reaction vessel (3). A level gauge (34) and a drain valve (35) are provided at the bottom of the liquid separator (26). The level gauge (34) and the drain valve (35) are electrically connected. The drain valve (35) is electrically connected to the PLC controller.

5. A flare gas incineration and treatment system for EVA production according to claim 1, characterized in that, The venting assembly includes an incinerator (14). A daily gas discharge valve (15) and an emergency gas discharge valve (16) are respectively installed on the pipelines connecting the incinerator (14) to the daily gas cooler (11) and the emergency gas cooler (12). An oxygen content analyzer (17), a hydrocarbon content analyzer (18), and a mixed flare gas inlet valve (19) are connected in series on the pipelines where the daily gas cooler (11) and the emergency gas cooler (12) intersect with the incinerator (14). The pipeline before the mixed flare gas inlet valve (19) is connected to the emergency gas buffer. The tank (2) is connected to and equipped with a flare gas bypass valve (20). A nitrogen purging pipeline (21) is provided on the pipeline connecting the daily gas cooler (11) and the emergency gas cooler (12) to the incinerator (14). A nitrogen purging valve (22) is provided on the nitrogen purging pipeline (21). An induced draft fan (23) is provided at the flue gas outlet of the incinerator (14). The outlet of the induced draft fan (23) is connected to a chimney (24). A mixed flare gas discharge valve (25) is provided on the pipeline connecting the induced draft fan (23) and the chimney (24).

6. A method for treating flare gas incineration during EVA production, characterized in that, Includes the following steps: S1: Daily Gas Collection: When it is necessary to collect the flare gas generated during EVA production, the operator first opens the daily gas inlet valve (5) and check valve (33) in sequence through the PLC controller, so that the flare gas generated in the reactor (3) and raw material storage tank (4) enters the daily gas buffer tank (1) to stabilize the flare gas pressure and flow fluctuations; the flow rate of the flare gas generated in the reactor (3) and raw material storage tank (4) is 50m³ / h. 3 / h-500m 3 / h, pressure is 0.1MPa-0.3MPa, and the pressure inside the daily gas buffer tank (1) is 0.15MPa-0.25MPa; S2: Emergency Gas Collection: If an overpressure or malfunction occurs during EVA production and an emergency shutdown is required, first open the emergency gas inlet valve (6) to release the gas. The flow rate generated during equipment depressurization is 1000 m³ / s. 3 / h-5000m 3 Flare gas with a pressure of 1.0MPa-2.0MPa is introduced into the emergency gas buffer tank (2) at a pressure of 1.0MPa-2.0MPa, and the pressure and flow rate of the flare gas are stabilized by the emergency gas buffer tank (2). S3: Liquid separation: Then, the PLC controller opens the daily gas outlet valve (9) and the emergency gas outlet valve (10) to introduce the flare gas in the daily gas buffer tank (1) and the emergency gas buffer tank (2) into the liquid separator (26) for gas-liquid separation, so that the liquid hydrocarbons, condensate and vinyl acetate precipitate in the flare gas are separated; then, the water seal inlet valve (31) is opened to introduce the liquid-separated flare gas into the water seal tank (28) to further intercept the liquid in the flare gas; S4: Cooling treatment: Then open the water seal outlet valve (13) to discharge the flare gas after separation treatment into the daily gas cooler (11) and the emergency gas cooler (12) for cooling, so that the vinyl acetate in the flare gas can be further condensed and separated. S5: Incineration treatment: Finally, open the daily gas discharge valve (15), emergency gas discharge valve (16), mixed flare gas inlet valve (19) and mixed flare gas discharge valve (25) in sequence to discharge the cooled flare gas into the incinerator (14) for combustion. The combustion temperature in the incinerator (14) is 900℃-1200℃. The residence time of the flare gas in the incinerator (14) is ≥2.5s. Then, it is discharged into the chimney (24) through the induced draft fan (23).

7. A method for treating flare gas combustion in EVA production according to claim 6, characterized in that, In S3, the water seal height for normal gas is 0.8m-1.2m, and the water seal height for emergency gas is 2.0m-2.5m.

8. A method for treating flare gas in EVA production according to claim 6, characterized in that, In S4, the flare gas is cooled to a temperature of 20°C-30°C by the daily gas cooler (11) and the emergency gas cooler (12).

9. A method for treating flare gas combustion in EVA production according to claim 6, characterized in that, In S5, when the flare gas passes through the oxygen content analyzer (17), the oxygen content analyzer (17) detects the oxygen content in the flare gas. If the oxygen content analyzer (17) detects that the oxygen content in the flare gas is ≥4 vol%, the mixed flare gas inlet valve (19) is closed by the PLC controller, and the nitrogen purge valve (22) is opened to replace the gas in the pipeline until the oxygen content in the pipeline is ≤1 vol%. Then the mixed flare gas inlet valve (19) is opened to allow the flare gas to be introduced into the incinerator (14) for combustion.

10. A method for treating flare gas in EVA production according to claim 6, characterized in that, In S5, before the flare gas enters the incinerator, the hydrocarbon content analyzer (18) detects the hydrocarbon content in the flare gas in real time. If the hydrocarbon content is ≤15%LEL, natural gas is introduced into the pipeline to maintain the hydrocarbon content in the flare gas at 25%LEL-50%LEL. If the hydrocarbon content is ≥90%LEL, the flare gas bypass valve (20) is opened through the PLC controller to discharge part of the flare gas into the emergency gas buffer tank (2) until the hydrocarbon content in the flare gas is 25%LEL-50%LEL.

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