PPVE recovery system based on molecular sieve membrane

Abstract

The invention relates to a PPVE (perfluoromethyl vinyl ether) tail gas recovery system, in particular to a recovery system for removing CO2 and N2 in PPVE tail gas by adopting a molecular sieve membrane matched with a condensation technology, and belongs to the field of gas treatment. According to the method, membrane separation and condensation processes are ingeniously coupled, CO2 and N2 in the PPVE tail gas can be effectively removed through efficient separation of the molecular sieve membrane on the tail gas and condensation separation of the condenser, the purity of PPVE is increased to 99.4%, and the recovery rate reaches up to 97.9%. Meanwhile, the membrane separation technology has the characteristics of high efficiency and energy conservation, a large amount of phase change energy consumption in a traditional method is avoided, the production cost is greatly reduced, the resource utilization rate is increased, and powerful support is provided for green and sustainable development of the fluorine chemical industry.

Description

Technical Field

[0001] The present invention relates to a perfluoromethyl vinyl ether tail gas (PPVE) recovery system, in particular to a recovery system which uses a molecular sieve membrane in combination with condensation technology to remove CO2 and N2 from the PPVE tail gas, belonging to the field of gas treatment. Background Art

[0002] PPVE (perfluoropropyl vinyl ether) is an important fluorinated functional monomer that plays a key role in the synthesis of high-performance fluoropolymers. Its molecular structure combines the stability of perfluoroalkyl groups with the reactivity of vinyl groups, allowing it to copolymerize with a variety of fluoroolefins. It is widely used in the preparation of ternary copolymers of fluoroelastomers (FKM) and fluororesins, imparting excellent high-temperature resistance, chemical corrosion resistance, and low permeability. It serves a wide range of high-end applications in aerospace, automotive, and semiconductor industries. The global PPVE market exceeded US$800 million in 2024, with China accounting for 35% of the market. However, there are few domestic PPVE manufacturers, resulting in tight supply and demand, with market prices exceeding 1 million yuan per ton.

[0003] During the decarboxylation reaction to produce PPVE, a large amount of carbon dioxide is produced, forming a mixture of PPVE and CO₂. Direct discharge or incineration not only wastes resources but also may cause environmental pollution, in violation of the relevant requirements of the "Comprehensive Control Plan for Volatile Organic Compounds in Key Industries." Recycling this PPVE not only helps improve raw material utilization and reduce production costs, but also achieves clean production and resource recycling, promoting the green and sustainable development of the fluorine chemical industry. Currently, PPVE recovery and purification technologies mainly include distillation, condensation, and adsorption. CN118359485B increases PPVE purity to 99.8% through a secondary distillation process; CN222143805U utilizes a three-stage condensation recovery process at -50°C to obtain PPVE with a purity of 99.5%. However, the distillation and condensation processes require large equipment investments, involve phase changes, and consume significant energy. Adsorption technologies can further improve purity. For example, the coupled distillation-adsorption process reported in CN109956855B produces PPVE with a purity exceeding 99.9%. However, adsorption separation is an intermittent operation, the adsorbent is easily saturated and requires frequent regeneration, and the process continuity is poor, which limits its industrial application.

[0004] As a green separation technology, membrane separation has significant advantages such as high efficiency and energy saving, simple process, and no "three wastes" emissions. Polymer membranes have been commercialized in some gas separation fields, but their performance is limited by the "permeability-selectivity trade-off effect" (trade-off effect), and they are prone to swelling during long-term contact with CO2 or fluorinated organic matter, affecting separation stability and service life. In contrast, inorganic molecular sieve membranes have excellent thermal and chemical stability, and have both high permeability and high selectivity. They are ideal membrane materials for recovering perfluoromethyl vinyl ether (PPVE) tail gas. Therefore, designing a PPVE recovery system based on molecular sieve membranes is an urgent problem to be solved. Summary of the Invention

[0005] To address the above issues, this patent proposes the use of molecular sieve membranes to efficiently separate PPVE tail gas, and further couples membrane separation with the condensation process, thereby reducing energy consumption while increasing the PPVE purity to 99.4% and the recovery rate to 97.9%.

[0006] The present invention provides a PPVE recovery system based on a molecular sieve membrane, which includes a condenser, a gas-liquid separator, a heater and a membrane separation device, wherein the condenser is arranged upstream of the gas-liquid separator to condense the tail gas and then perform gas-liquid separation, the heater is arranged upstream of the membrane separation device to heat the tail gas and then pass it into the membrane separation device for separation, the membrane separation device uses a molecular sieve membrane as a membrane separation element, and the combination of the heater and the membrane separation device is arranged upstream or downstream of the condenser and gas-liquid separator combination, and the molecular sieve membrane has a CO2 / PPVE and N2 / PPVE separation selectivity range of 30-300 and 20-100, respectively.

[0007] Preferably, the condenser has two stages, and the membrane separation device is arranged downstream of the two-stage condenser.

[0008] Preferably, the PPVE recovery system includes a first condenser, a first gas-liquid separator, a second condenser, a second gas-liquid separator, a heater, a membrane separation device and a vacuum pump connected in sequence according to the order of tail gas treatment, wherein the gas outlet of the first gas-liquid separator is connected to the second condenser, the gas outlet of the second gas-liquid separator is connected to the heater, and the vacuum pump is connected to the permeate side of the membrane separation device; the retentate side of the membrane separation device is connected to the air inlet of the first condenser and an exhaust port is left.

[0009] Preferably, the condensation temperature of the first condenser is -20~-10℃, the condensation temperature of the second condenser is -30~-20℃, the heating temperature of the heater is 60-80℃, and the membrane separation device processes 1m 3 The membrane area required for / h tail gas is 1-2m 2 .

[0010] Preferably, the condenser has two stages, and the membrane separation device is arranged in the middle of the two-stage condenser.

[0011] Preferably, the PPVE recovery system includes a first condenser, a first gas-liquid separator, a heater, a membrane separation device, a second condenser, and a second gas-liquid separator connected in sequence according to the order of tail gas treatment, the gas outlet of the first gas-liquid separator is connected to the heater, the retentate side of the membrane separation device is connected to the second condenser, and the permeate side of the membrane separation device is connected to the vacuum pump.

[0012] Preferably, the condensation temperature of the first condenser is -30 to -10 °C, the condensation temperature of the second condenser is -30 to -20 °C, the heating temperature of the heater is 60-80 °C, and the membrane separation device processes 1 m 3 The membrane area required for / h tail gas is 0.5-1.5 m 2 .

[0013] Preferably, the membrane separation device is arranged upstream of the condenser, and no condenser is arranged upstream of the membrane separation device.

[0014] Preferably, the PPVE recovery system includes, in order of exhaust gas treatment, a heater, a compressor, a membrane separation device, a first condenser, and a first gas-liquid separator, connected in sequence. The retentate side of the membrane separation device is connected to the first condenser, and the permeate side of the membrane separation device is connected to a vacuum pump. The heater and compressor in the system can be turned on or off depending on the temperature and pressure of the exhaust gas.

[0015] Preferably, the heating temperature of the heater is 60-80°C, the pressure of the compressor is 0.05-0.3 MPa, the condensation temperature of the first condenser is -20~-10°C, and the membrane separation device processes 1m 3 The membrane area required for / h tail gas is 0.5-2 m 2 .

[0016] The molecular sieve membrane-based PPVE recovery system provided by the present invention utilizes the coordinated cooperation of a condenser and a membrane separation device to achieve a significant improvement in the purity and recovery rate of PPVE.

[0017] Preferably, the content of PPVE in the tail gas is 2-10%, the CO2 content is 40-80%, and the N2 content is 20-60%.

[0018] Preferably, the molecular sieve membrane is selected from one or more of CHA type, DDR type, MFI type, LTA type, and STT type molecular sieve membranes.

[0019] Preferably, the molecular sieve membrane is one or more of a flat membrane, a tubular membrane, a multi-channel membrane or a hollow fiber membrane structure.

[0020] Preferably, the operating pressure of the membrane separation device is 0.1-1.0 MPa, and the operating temperature is 30-100°C.

[0021] Compared with the prior art, the present invention has the following advantages: First, compared to existing PPVE recovery technologies, this method cleverly couples membrane separation with condensation processes, utilizing a condenser to condense and separate the tail gas, and a molecular sieve membrane for efficient separation. This effectively removes CO₂ and N₂ from PPVE tail gas, increasing PPVE purity to 99.4% and achieving a recovery rate of 97.9%. Furthermore, membrane separation technology is inherently efficient and energy-efficient, avoiding the significant phase change energy consumption associated with traditional methods. This significantly reduces production costs and improves resource utilization, providing strong support for the green and sustainable development of the fluorine chemical industry.

[0022] Secondly, the present invention adopts a molecular sieve membrane with specific properties as the membrane separation element, which has excellent thermal stability and chemical stability, can maintain stable separation performance in a complex exhaust gas environment, and is not affected by factors such as swelling, thereby extending the service life of the membrane separation device.

[0023] In addition, the PPVE recovery system provided by the present invention can flexibly adjust the setting position of the membrane separation device according to actual production needs, such as setting it downstream, in the middle or upstream of the two-stage condenser, and the molecular sieve membrane has a variety of types and structures to choose from, and the operating pressure and temperature also have a wide range, which makes the system more widely applicable and can meet the needs of PPVE tail gas recovery in different production scenarios, further improving the practicality and competitiveness of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Long-term stability test results of the CHA molecular sieve membrane in recovering perfluoromethyl vinyl ether (PPVE) tail gas in Example 5; Figure 2 This is a process flow chart of Example 6 of the present invention; Figure 3 This is a process flow chart of Example 7 of the present invention; Figure 4 This is a process flow chart of Example 8 of the present invention; Figure 5 This is a process flow chart of Comparative Example 1 of the present invention; Explanation of the accompanying drawings: 1. First condenser, 2. First gas-liquid separator, 3. Second condenser, 4. Second gas-liquid separator, 5. Heater, 6. Membrane separation device, 7. Vacuum pump, 8. Compressor. DETAILED DESCRIPTION

[0025] Example 1 The perfluoromethyl vinyl ether tail gas contained 6% PPVE, 71% CO2, and 23% N2. The membrane separation module used an STT molecular sieve membrane. The operating pressure and temperature of the module were 0.11 MPa and 30°C. The CO2 removal efficiency and N2 removal efficiency of the module were 94% and 40%, respectively. The PPVE concentration on the retentate side increased to 30%, and the PPVE loss rate was 0.4%. At this point, the membrane's CO2 / PPVE and N2 / PPVE selectivities were 225 and 67, respectively.

[0026] Example 2 The perfluoromethyl vinyl ether tail gas contained 3.3% PPVE, 46% CO2, and 50.7% N2. The membrane separation module used a DDR molecular sieve membrane. The operating pressure and temperature of the module were 0.4 MPa and 50°C. The CO2 removal efficiency and N2 removal efficiency of the module were 99.98% and 81%, respectively. The PPVE concentration on the retentate side increased to 33%, and the PPVE loss rate was 1.3%. At this point, the membrane's CO2 / PPVE and N2 / PPVE selectivities were 80 and 42, respectively.

[0027] Example 3 The perfluoromethyl vinyl ether tail gas contained 4.5% PPVE, 51% CO2, and 44.5% N2. The membrane separation module used an MFI molecular sieve membrane. The operating pressure and temperature of the module were 0.25 MPa and 60°C. The CO2 removal efficiency and N2 removal efficiency were 99.3% and 91%, respectively. The PPVE concentration on the retentate side increased to 36%, and the PPVE loss rate was 4.7%. At this point, the membrane's CO2 / PPVE and N2 / PPVE selectivities were 48 and 35, respectively.

[0028] Example 4 The perfluoromethyl vinyl ether tail gas contained 6% PPVE, 71% CO2, and 23% N2. The membrane separation module used an LTA molecular sieve membrane. The operating pressure and temperature of the module were 0.2 MPa and 70°C. The CO2 removal efficiency and N2 removal efficiency of the module were 89% and 29%, respectively. The PPVE concentration on the retentate side increased to 27%, and the PPVE loss rate was 0.3%. At this point, the membrane's CO2 / PPVE and N2 / PPVE selectivities were 204 and 69, respectively.

[0029] Example 5 The PPVE content in the tail gas of perfluoromethyl vinyl ether is 6%, the CO2 content is 61%, and the N2 content is 33%. The membrane in the membrane separation component adopts CHA type molecular sieve membrane. The operating pressure of the membrane separation component is 0.2 MPa, and the operating temperature is 50 °C. The CO2 removal rate of the membrane separation component is 99.8%, the N2 removal rate is 85%, the PPVE concentration on the retentate side is increased to 59%, and the PPVE loss rate is <1.5%. At this time, the CO2 / PPVE and N2 / PPVE selectivities of the membrane are 87 and 64, respectively. The cumulative operation time of membrane separation is up to 800 h (20 days), and the separation performance remains stable (such as Figure 1 shown).

[0030] Example 6 like Figure 2 As shown, the PPVE recovery system based on the molecular sieve membrane provided in this embodiment includes, in accordance with the order of tail gas treatment, a first condenser 1, a first gas-liquid separator 2, a second condenser 3, a second gas-liquid separator 4, a heater 5, a membrane separation device 6 and a vacuum pump 7, which are connected in sequence, wherein the gas outlet of the first gas-liquid separator 2 is connected to the second condenser 3, the gas outlet of the second gas-liquid separator 4 is connected to the heater 5, and the vacuum pump 7 is connected to the permeate side of the membrane separation device 6. The retentate side of the membrane separation device 6 is connected to the air inlet of the first condenser 1 and an exhaust port is left. The membrane separation device 6 uses the CHA type molecular sieve membrane of Example 5 as a membrane separation element.

[0031] This example uses a membrane separation process coupled with a condensation process to purify PPVE from perfluoromethyl vinyl ether tail gas. The tail gas contains 11.5% PPVE, 76.5% CO₂, and 12% N₂. The gas pressure is 0.11 MPa, the gas temperature is 75°C, and the gas flow rate is 50 m³·h⁻¹ (standard conditions). The tail gas enters the first condenser 1 (condensation temperature is -15 ℃), and then enters the first gas-liquid separator 2. The PPVE content of the bottom liquid phase outlet product is 95.85%, the N2 content is 0.09251%, and the CO2 content is 4.056%. The PPVE content of the top gas phase outlet product is 4.571%, the N2 content is 27.11%, and the CO2 content is 68.32%. The gas discharged from the top gas phase outlet is condensed by the second condenser 3 (condensation temperature is -25 ℃) and then enters the second gas-liquid separator 4. The PPVE content of the bottom liquid phase outlet product is 94.61%, the N2 content is 0.09601%, and the CO2 content is 5.290%. The PPVE content of the top gas phase outlet product is 2.173%, the N2 content is 27.83%, and the CO2 content is 70.00%. The gas phase outlet product at the top of the second condenser 4 is heated by the heater 5 (heating temperature is 75 After heating at 100 °C, the liquid enters membrane separation unit 6 for membrane separation. The permeate-side gas phase product has a PPVE content of 0.01156%, a N2 content of 11.48%, and a CO2 content of 88.51%. The retentate-side gas phase product has a PPVE content of 8.703%, a N2 content of 77.22%, and a CO2 content of 14.07%. The permeate-side gas is directly vented, while the retentate-side gas, after 10% venting to remove some non-condensable gases, is recirculated to the first condenser 1 for secondary recovery. The PPVE recovery rate of the entire process is approximately 97.8%, and the PPVE concentration increases to 94.61% (second gas-liquid separator) and 95.85% (first gas-liquid separator). The total process energy consumption is 8.30 kW, and the required membrane area is 70 m2.

[0032] Example 7 like Figure 3 As shown, the molecular sieve membrane-based PPVE recovery system provided in this embodiment includes, in the order of tail gas treatment, a first condenser 1, a first gas-liquid separator 2, a heater 5, a membrane separation device 6, a second condenser 3, and a second gas-liquid separator 4. The gas outlet of the first gas-liquid separator 2 is connected to the heater 5, the retentate side of the membrane separation device 6 is connected to the second condenser 3, and the permeate side of the membrane separation device 6 is connected to a vacuum pump 7. The membrane separation device 6 uses the CHA molecular sieve membrane of Example 5 as a membrane separation element.

[0033] A membrane separation process coupled with a condensation process was used to purify PPVE from perfluoromethyl vinyl ether tail gas. The tail gas contained 11.5% PPVE, 76.5% CO₂, and 12% N₂. The gas pressure was 0.11 MPa, the temperature was 75°C, and the flow rate was 50 m³·h⁻¹ (standard conditions). The tail gas enters the first condenser 1 (condensation temperature is -25 ℃), and then enters the first gas-liquid separator 2. The PPVE content of the bottom liquid phase outlet product is 93.57%, the N2 content is 0.04604%, and the CO2 content is 6.386%. The PPVE content of the top gas phase outlet product is 2.158%, the N2 content is 13.34%, and the CO2 content is 84.50%. The gas discharged from the top gas phase outlet is heated by the heater 5 (heating temperature is 75 ℃) and then enters the membrane separation device 6 for membrane separation. The PPVE content of the permeate side gas phase product is 0.01022%, the N2 content is 4.899%, and the CO2 content is 95.09%. The PPVE content of the retentate side gas phase product is 13.79%, the N2 content is 59.09%, and the CO2 content is 27.12%. The permeate gas is directly vented, while the retentate gas is condensed in the second condenser 3 (condensation temperature: -25°C) before entering the second gas-liquid separator 4. The bottom liquid phase outlet product has a PPVE content of 97.46%, a N2 content of 0.02320%, and a CO2 content of 2.310%. The top gas phase outlet product has a PPVE content of 2.21%, a N2 content of 67.24%, and a CO2 content of 30.55%. The PPVE recovery rate for the entire process is approximately 97.6%, and the PPVE concentration increases to 93.57% (first gas-liquid separator) and 97.46% (second gas-liquid separator). The total process energy consumption is 7.67 kW, and the required membrane area is 50 m2.

[0034] Example 8 like Figure 4 As shown, the molecular sieve membrane-based PPVE recovery system provided in this embodiment includes, in the order of tail gas treatment, a heater 5, a compressor 8, a membrane separation device 6, a first condenser 1, and a first gas-liquid separator 2 connected in sequence. The retentate side of the membrane separation device 6 is connected to the first condenser 1, and the permeate side of the membrane separation device 6 is connected to a vacuum pump 7. The membrane separation device 6 uses the CHA molecular sieve membrane of Example 5 as a membrane separation element.

[0035] A membrane separation process coupled with a condensation process was used to purify PPVE from perfluoromethyl vinyl ether tail gas. The tail gas contained 11.5% PPVE, 76.5% CO₂, and 12% N₂. The gas pressure was 0.11 MPa, the gas temperature was 75°C, and the gas flow rate was 50 m³·h⁻¹ (standard conditions). The tail gas passed through heater 5 (not activated) and compressor 8 (not activated) and entered membrane separation unit 6. The permeate-side gas phase contained 0.07153% PPVE, 5.226% N₂, and 94.70% CO₂. The retentate-side gas phase contained 58.31% PPVE, 39.74% N₂, and 1.949% CO₂. The retentate gaseous product was condensed in the first condenser 1 (condensation temperature -15°C) and then entered the first gas-liquid separator 2. The bottom liquid phase outlet product had a PPVE content of 99.36%, a N2 content of 0.3231%, and a CO2 content of 0.3163%. The top gaseous phase outlet product had a PPVE content of 2.234%, a N2 content of 93.59%, and a CO2 content of 4.179%. The PPVE recovery rate for the entire process was approximately 97.9%, and the PPVE concentration increased to 99.4%. The total process energy consumption was 3.82 kW, and the required membrane area was 80 m2.

[0036] Comparative Example 1 like Figure 5 As shown, the comparative PPVE recovery system includes a first condenser 1, a first gas-liquid separator 2, a second condenser 3, and a second gas-liquid separator 4 connected in sequence according to the order of tail gas treatment, wherein the gas outlet of the first gas-liquid separator 2 is connected to the second condenser 3, and the gas outlet of the second gas-liquid separator 4 is the product.

[0037] A two-stage condensation process was used to purify PPVE in the tail gas of perfluoromethyl vinyl ether. The PPVE content in the tail gas was 11.5%, the CO2 content was 76.5%, and the N2 content was 12%. The gas pressure was 0.11 MPa, the gas temperature was 75 ℃, and the gas flow rate was 50 m3·h-1 (standard conditions). The tail gas entered the first condenser 1 (condensation temperature was -15 ℃), and then entered the first gas-liquid separator 2. The PPVE content in the bottom liquid phase outlet product was 95.06%, the N2 content was 0.04436%, and the CO2 content was 4.895%. The PPVE content in the top gas phase outlet product was 4.550%, the N2 content was 12.99%, and the CO2 content was 82.46%; the gas discharged from the top gas phase outlet passed through the second condenser 3 (condensation temperature was -25 After condensation at 40°C, the product enters the second gas-liquid separator (4). The bottom liquid phase outlet product has a PPVE content of 93.57%, a N2 content of 0.04604%, and a CO2 content of 6.386%. The top gas phase outlet product has a PPVE content of 2.158%, a N2 content of 13.34%, and a CO2 content of 84.50%. The PPVE recovery rate of the entire process is approximately 83%, and the PPVE concentration increases to 93.57% (second gas-liquid separator) and 95.06% (first gas-liquid separator). The total energy consumption of the process is 4.96 kW.

[0038] Table 1 summarizes the purification results obtained using different processes in Examples 6-8 and Comparative Example 1. As shown in Table 1, compared to the two-stage cooling process, the membrane separation process coupled with the condensation process can increase the PPVE recovery rate from 83.1% to 97.6-97.9%. Specifically, the pre-condensation membrane separation process in Example 8 reduced energy consumption from 4.96 kW to 3.82 kW, while increasing PPVE purity to 99.4%.

[0039] Table 1 Summary of purification results of different processes

Claims

1. A PPVE recovery system based on molecular sieve membrane, characterized in that: The PPVE recovery system includes a condenser, a gas-liquid separator, a heater and a membrane separation device, wherein the condenser is arranged upstream of the gas-liquid separator to condense the tail gas and then perform gas-liquid separation, the heater is arranged upstream of the membrane separation device to heat the tail gas and then pass it into the membrane separation device for separation, the membrane separation device uses a molecular sieve membrane as a membrane separation element, and the combination of the heater and the membrane separation device is arranged upstream or downstream of the condenser and gas-liquid separator combination, and the molecular sieve membrane has a CO2 / PPVE and N2 / PPVE separation selectivity range of 30-300 and 20-100, respectively.

2. The PPVE recovery system according to claim 1, characterized in that: The condenser has two stages, and the membrane separation device is arranged downstream of the two-stage condenser.

3. The PPVE recovery system according to claim 2, characterized in that: The PPVE recovery system includes, in accordance with the order of tail gas treatment, a first condenser, a first gas-liquid separator, a second condenser, a second gas-liquid separator, a heater, a membrane separation device and a vacuum pump, which are connected in sequence, wherein the gas outlet of the first gas-liquid separator is connected to the second condenser, the gas outlet of the second gas-liquid separator is connected to the heater, and the vacuum pump is connected to the permeate side of the membrane separation device; the retentate side of the membrane separation device is connected to the air inlet of the first condenser and an exhaust port is left.

4. The PPVE recovery system according to claim 3, characterized in that: The condensation temperature of the first condenser is -20~-10 ℃, the condensation temperature of the second condenser is -30~-20 ℃, the heating temperature of the heater is 60-80 ℃, and the membrane separation device processes 1 m 3 The membrane area required for / h tail gas is 1-2 m 2 .

5. The PPVE recovery system according to claim 1, characterized in that: The condenser has two stages, and the membrane separation device is arranged in the middle of the two-stage condenser.

6. The PPVE recovery system according to claim 5, characterized in that: The PPVE recovery system includes a first condenser, a first gas-liquid separator, a heater, a membrane separation device, a second condenser, and a second gas-liquid separator connected in sequence according to the order of tail gas treatment. The gas outlet of the first gas-liquid separator is connected to the heater, the retentate side of the membrane separation device is connected to the second condenser, and the permeate side of the membrane separation device is connected to a vacuum pump.

7. The PPVE recovery system according to claim 6, characterized in that: The condensation temperature of the first condenser is -30~-10 ℃, the condensation temperature of the second condenser is -30~-20 ℃, the heating temperature of the heater is 60-80 ℃, and the membrane separation device processes 1 m 3 The membrane area required for / h tail gas is 0.5-1.5 m 2 .

8. The PPVE recovery system according to claim 1, characterized in that: The membrane separation device is arranged upstream of the condenser, and no condenser is arranged upstream of the membrane separation device.

9. The PPVE recovery system according to claim 8, characterized in that: The PPVE recovery system includes a heater, a compressor, a membrane separation device, a first condenser and a first gas-liquid separator connected in sequence according to the tail gas treatment order. The retentate side of the membrane separation device is connected to the first condenser, and the permeate side of the membrane separation device is connected to the vacuum pump.

10. The PPVE recovery system according to claim 9, characterized in that: The heating temperature of the heater is 60-80 ℃, the pressure of the compressor is 0.05-0.3 MPa, the condensation temperature of the first condenser is -20~-10 ℃, and the membrane separation device processes 1m 3 The membrane area required for / h tail gas is 0.5-2 m 2 .

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