Device and process method for recovering tail gas of diketene rectification vacuum pump
By designing the exhaust gas recovery device of divinylone distillation vacuum pump, the exhaust gas is introduced into the cracking furnace for high-temperature incineration, which solves the problem of exhaust gas treatment of the distillation vacuum pump, and achieves environmentally friendly production and cost savings.
Patent Information
- Application Number
- CN202411484970.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-23
- Publication Date
- 2025-02-28
AI Technical Summary
During the divinylone distillation process, the cooling of the distillation vacuum pump requires a large amount of water, resulting in the water containing divinylone or other volatile organic matter, causing waste and environmental pollution. At the same time, the gases at the pump outlet also contain toxic divinylone.
A divinylone distillation vacuum pump exhaust gas recovery device is designed, which absorbs exhaust gas through a distillation activated carbon tank, and the distilled water washing tower absorbs exhaust gas through a normal temperature water, and then enters a cracking furnace through a distilled water seal for high-temperature incineration at 800℃.
It effectively solves the problem of compliance with exhaust gas, saves fuel, reduces production costs, reduces pollution, and achieves energy conservation, emission reduction and environmentally friendly production.
Smart Images
Figure CN119524567A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of diketene production, and in particular relates to a device and a process method for recovering tail gas of a diketene distillation vacuum pump. Background Art
[0002] The preparation of diketene by acetic acid cracking mainly includes the steps of acetic acid cracking, ketene absorption and polymerization, crude product treatment and distillation purification. The raw material glacial acetic acid produces crude diketene in the cracking furnace section. After the crude diketene is sent to the distillation system for diketene distillation, the diketene content reaches more than 97.5%, which is considered a qualified diketene finished product.
[0003] For diketene distillation, the distillation system mainly performs:
[0004] 1) The crude diketene is first transported from the cracking absorption station to the crude diketene high-level tank (feeding tank), and the high-level tank is used to store and supply the crude diketene; the cracking absorption station heats acetic acid by steam to form acetic acid vapor, which enters the cracking furnace and cracks into ketene, and the prepared 96% glacial acetic acid is heated into gas phase by an acetic acid evaporator and mixed with diammonium hydrogen phosphate solution in a ratio of 80:1, and then heated by the cracking furnace to generate ketene gas, and then condensed, purified, and absorbed to obtain crude diketene liquid. The crude diketene has a diketene content of ≥92.3% and an acetic anhydride content of ≤5%.
[0005] 2) After the crude diketene flows out from the high-level tank, it passes through a rotor flowmeter, which is used to preliminarily measure and monitor the flow of the crude diketene; subsequently, after the crude diketene is more accurately regulated by a remote explosion-proof flowmeter, the crude diketene can enter the membrane evaporator at a uniform and stable speed;
[0006] 3) The film evaporator adopts jacket heating, that is, heat is transferred to the crude diketene inside the film evaporator through the jacket of the film evaporator; the film evaporator adopts the design of centrifugal basket and spinner. The centrifugal basket is located inside the evaporator, and generates centrifugal force through rotation, and the crude diketene is thrown out from the spinner (the spinner is located about 70cm from the top of the film evaporator cover) and evenly distributed on the four walls of the film evaporator for evaporation;
[0007] 4) The diketene vapor produced by the evaporation of crude diketene is separated, decolorized and further purified by a packed tower, then enters a condenser to be condensed into refined diketene and then enters a receiving tank for collection. The solid and liquid enter the residue intermediate kettle for secondary distillation, so that a small amount of crude diketene in it is converted into diketene vapor and enters the packed tower. The residue after secondary distillation enters the residue dilution kettle, and is fully stirred with the 100kg pump liquid added previously and enters the next process.
[0008] The diketene distillation process belongs to negative pressure production, and the main equipment for providing negative pressure in the negative pressure production process is the distillation vacuum pump. The function of the distillation vacuum pump connected to the distillation system is to maintain a certain negative pressure state in the distillation system. When the distillation vacuum pump is in operation, water cooling is usually used to seal the pump body. During normal production, the distillation vacuum pump needs to consume a large amount of water for cooling. These waters often contain a certain amount of diketene or other volatile organic compounds, which not only wastes materials, but also requires sewage treatment, and has an impact on the environment. At the same time, the gas discharged from the outlet of the distillation vacuum pump also contains toxic gases such as diketene. Therefore, how to realize the recovery and comprehensive utilization of the tail gas of the distillation vacuum pump has become a difficult problem that needs to be solved urgently in the diketene industry. Summary of the invention
[0009] In order to solve the above technical problems, that is, in the normal production process, the distillation vacuum pump needs to consume a large amount of water for cooling. The water often contains a certain amount of diketene or other volatile organic compounds, which not only wastes materials, but also requires sewage treatment and affects the environment. At the same time, the gas discharged from the outlet of the distillation vacuum pump also contains toxic gases such as diketene.
[0010] The present invention provides the following technical solutions:
[0011] First,
[0012] The invention provides a device for recovering tail gas of a diketene distillation vacuum pump, comprising a distillation kettle, wherein materials for producing diketene are in the distillation kettle, and further comprising a distillation buffer tank, a distillation oil tank, a distillation vacuum pump, a distillation activated carbon tank, a distillation water washing tower, a distillation water seal, and a cracking furnace. The distillation kettle is connected with the top of the distillation buffer tank through a pipeline, the distillation buffer tank is connected with the top of the distillation oil tank through a pipeline, the distillation oil tank is connected in series with the distillation vacuum pump through a pipeline, the distillation vacuum pump is connected with the distillation activated carbon tank through a pipeline, the distillation activated carbon tank is connected with the distillation water washing tower through a pipeline, the distillation water washing tower is connected with the distillation water seal through a pipeline, and the distillation water seal is connected with the cracking furnace through a pipeline.
[0013] Furthermore, the pressure in the distillation buffer tank is ≥-90Kpa.
[0014] Furthermore, the reaction temperature in the distillation oil tank is ≤18°C and the pressure is normal pressure.
[0015] Furthermore, the distillation oil tank is connected in series to two parallel distillation vacuum pumps through a pipeline, including distillation vacuum pump one and distillation vacuum pump two. The inlet of distillation vacuum pump one is provided with inlet valve one, and the outlet of distillation vacuum pump one is provided with outlet valve one; the inlet of distillation vacuum pump two is provided with inlet valve two, and the outlet of distillation vacuum pump two is provided with outlet valve two.
[0016] Furthermore, an inlet valve three is provided at the inlet of the distillation activated carbon tank.
[0017] Furthermore, a pipeline is connected to the top of the distillation water washing tower, and an emergency vent valve 1 is provided on the pipeline.
[0018] Furthermore, an emergency shut-off valve 1 is provided at the inlet of the distillation water seal.
[0019] Furthermore, a pipeline is connected to the top of the distillation water seal, and a second emergency vent valve is provided on the pipeline.
[0020] Furthermore, the distillation water seal is connected to the burner of the cracking furnace through a pipeline, and an emergency shut-off valve 2 is arranged on the pipeline.
[0021] Second,
[0022] The present invention provides a process for recovering a diketene distillation vacuum pump, comprising the steps of:
[0023] Step S1, during the operation of the distillation vacuum pump, the tail gas at the outlet enters the distillation activated carbon tank through a pipeline, and the activated carbon adsorbs the tail gas;
[0024] Step S2: After the activated carbon absorbs the tail gas, the tail gas from the distillation vacuum pump enters the distillation water washing tower and is absorbed by normal temperature water;
[0025] Step S3, after being absorbed by water at room temperature, the tail gas of the distillation vacuum pump enters the distillation water seal through a pipeline;
[0026] Step S4: After passing through the distillation water seal, the tail gas of the distillation vacuum pump enters the cracking furnace and is burned and decomposed at a high temperature above 800°C.
[0027] Compared with the prior art, the present invention has the following beneficial effects:
[0028] The invention uses activated carbon adsorption and water absorption to adsorb diketene tail gas in the production cycle of diketene distillation vacuum pump, and then introduces the tail gas of the distillation vacuum pump into the distillation water seal and enters the cracking furnace for high-temperature incineration at 800°C, which not only solves the problem of tail gas meeting the standards, but also saves fuel, reduces production costs and reduces pollution, and ultimately achieves the purpose of energy saving, emission reduction and environmentally friendly production. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 The invention discloses a device for recovering tail gas from a diketene distillation vacuum pump.
[0030] Reference numerals:
[0031] 1. Distillation oil tank; 2. Distillation buffer tank; 3. Distillation kettle; 4. Distillation activated carbon tank; 5. Distillation water washing tower; 6. Distillation water seal; 7. Cracking furnace;
[0032] 8. Inlet valve 1; 9. Inlet valve 2; 10. Outlet valve 1; 11. Outlet valve 2; 12. Inlet valve 3; 13. Emergency vent valve 1; 14. Emergency shut-off valve 1; 15. Emergency vent valve 2; 16. Emergency shut-off valve 2;
[0033] 17. Distillation vacuum pump one; 18. Distillation vacuum pump two. DETAILED DESCRIPTION
[0034] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the protection scope of the present invention.
[0035] It should be noted that the directions or positional relationships indicated by terms such as “center”, “up”, “down”, “horizontal”, “left”, “right”, “front”, “back”, “lateral” and “longitudinal” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.
[0036] Example 1
[0037] like Figure 1 As shown, the present invention provides a device for recovering tail gas from a diketene distillation vacuum pump, comprising a distillation kettle 3, a distillation buffer tank 2, a distillation oil tank 1, a distillation vacuum pump, a distillation activated carbon tank 4, a distillation water washing tower 5, a distillation water seal 6, and a cracking furnace 7.
[0038] In the production process of diketene, the distillation kettle 3 is a crucial equipment, which is mainly used to evaporate and separate the crude diketene. The distillation kettle 3 can separate diketene from other impurities with different boiling points, thereby obtaining a relatively pure diketene product.
[0039] The distillation vacuum pump plays a key role in maintaining the negative pressure of the system during the distillation process. The distillation vacuum pump will discharge a certain amount of tail gas during operation. In addition to the uncondensed diketene vapor, the tail gas may also contain VOCs (volatile organic compounds), CO 2 , CO and other gases. Since the tail gas contains harmful substances such as diketene, directly discharging it into the atmosphere will pollute the environment and also pose a safety hazard. Through high-temperature combustion, the harmful substances in the tail gas are converted into harmless carbon dioxide and water vapor, thereby achieving the purpose of purifying the tail gas.
[0040] The distillation kettle 3, the material for producing diketene is in the distillation kettle 3, and the distillation kettle 3 is the evaporator of the crude diketene. The vacuum degree of the distillation kettle 3 is ≥-90Kpa. The distillation kettle 3 is mainly composed of a film evaporator and a residue intermediate kettle.
[0041] The membrane evaporator is mainly used for the preliminary separation and purification of diketene. The diketene in the raw material is evaporated by heating, and the selective permeation of the membrane is used to preliminarily separate diketene from other impurities (such as acetic anhydride). The top temperature of the membrane evaporator is 55℃-75℃, which is conducive to the evaporation of diketene and avoids decomposition or side reactions caused by excessively high temperatures. The bottom temperature of the membrane evaporator is 70℃-90℃, which is slightly higher than the top temperature, which helps to maintain the stability of the evaporation process and promotes the effective transfer of heat.
[0042] The residue intermediate kettle is used to collect and process high-concentration impurities and incompletely evaporated materials discharged from the film evaporator. Through further heating and possible chemical reactions, the residual diketene is further purified, while the content of impurities such as acetic anhydride is reduced. The temperature of the residue intermediate kettle is 0℃-100℃. Higher temperatures help promote the decomposition of impurities and the evaporation of residual diketene, but it is also necessary to avoid the negative effects caused by excessively high temperatures.
[0043] The distillation kettle 3 reacts under the aforementioned temperature and pressure conditions to generate diketene. The raw material of diketene is crude diketene, wherein the diketene (DK) content is ≥92% and the acetic anhydride content is ≤6%; it is processed into finished diketene in the distillation kettle 3, wherein the diketene (DK) content is ≥97.5% and the acetic anhydride content is ≤1.5%.
[0044] The top of the distillation buffer tank 2 is connected to the middle of the distillation kettle 3 through a pipeline. The distillation buffer tank 2 is mainly used to receive and temporarily store the diketene tail gas from the distillation kettle 3. It plays a buffering and stabilizing role to prevent the tail gas from being directly discharged into the atmosphere to cause pollution or safety hazards.
[0045] The diketene tail gas in the distillation kettle 3 is transported to the distillation buffer tank 2 through a pipeline. The working condition in the distillation buffer tank 2 is a temperature ≤ 18°C. This temperature limit is to prevent diketene from condensing or crystallizing in the distillation buffer tank 2. Diketene is a volatile liquid, but it may become viscous or solid at a lower temperature. Therefore, controlling the temperature below 18°C can ensure that the diketene in the tail gas remains in a gaseous state, which is convenient for subsequent treatment.
[0046] The pressure in the distillation buffer tank 2 is ≥-90Kpa, and the negative pressure environment (i.e., the pressure is lower than the atmospheric pressure) helps to reduce the leakage and diffusion of volatile substances in the tail gas. At the same time, the pressure condition of -90Kpa matches the vacuum degree in the distillation kettle 3, which can ensure that the diketene tail gas is smoothly transported from the distillation kettle 3 to the distillation buffer tank 2. This pressure control also helps to improve the efficiency and safety of tail gas treatment.
[0047] The distillation oil tank 1 and the distillation buffer tank 2 are connected to the top of the distillation oil tank 1 through a pipeline, and the diketene tail gas in the distillation buffer tank 2 is transported into the distillation oil tank 1. The distillation oil tank 1 serves as a buffer tank and a standby tank.
[0048] The reaction temperature in the distillation oil tank 1 is ≤18°C and the pressure is normal pressure; the distillation oil tank 1 contains 25# transformer oil, which is also called type A insulating oil and is a kind of electrical insulating oil. The freezing point of 25# transformer oil is -25°C, which is also the main basis for its naming.
[0049] The 25# transformer oil in the distillation oil tank 1 is indirectly cooled by refrigerated brine and serves as a cooling medium for the distillation vacuum pump while absorbing impurities in the diketene gas.
[0050] The distillation vacuum pump, the distillation oil tank 1 is connected in series with two parallel distillation vacuum pumps through a pipeline, including a distillation vacuum pump 17 and a distillation vacuum pump 2 18, one of which is in normal use and the other is spare. The two distillation vacuum pumps are connected to the bottom of the distillation activated carbon tank 4 through a pipeline, and the distillation vacuum pump transports the diketene tail gas into the distillation activated carbon tank 4.
[0051] An inlet valve 8 is provided at the inlet of the distillation vacuum pump 17, and an outlet valve 10 is provided at the outlet of the distillation vacuum pump 17; an inlet valve 9 is provided at the inlet of the distillation vacuum pump 18, and an outlet valve 11 is provided at the outlet of the distillation vacuum pump 18.
[0052] When a distillation vacuum pump needs to be overhauled or maintained, the corresponding inlet valve and outlet valve of the distillation vacuum pump can be closed, so that the pump can be safely disassembled, inspected or parts replaced without affecting the operation of other parts of the system.
[0053] Depending on production needs, you can choose to start one or two distillation vacuum pumps. For example, when the production load is low, you may only need to run one distillation vacuum pump; when the load is high or a higher vacuum degree is required, you can start two distillation vacuum pumps in parallel.
[0054] The distillation activated carbon tank 4 uses activated carbon to absorb the diketene tail gas. An inlet valve 3 12 is provided at the inlet of the distillation activated carbon tank 4 to control whether the diketene tail gas enters the distillation activated carbon tank 4.
[0055] The upper part of the distillation activated carbon tank 4 is connected to the bottom of the distillation water washing tower 5 through a pipeline, and the diketene tail gas is transported into the distillation water washing tower 5 through the pipeline. The distillation water washing tower 5 absorbs the diketene tail gas through normal temperature water and recovers a part of the materials in the tail gas, thereby reducing the impact of direct tail gas discharge on the environment.
[0056] The top of the distillation water washing tower 5 is connected to an emergency vent valve 13. When the pressure in the distillation water washing tower 5 rises abnormally, such as 2Kpa-5Kpa, the emergency vent valve 13 is opened, and the distillation water washing tower 5 vents the tail gas of the distillation vacuum pump directly to the atmosphere to reduce the pressure in the distillation water washing tower 5, prevent equipment damage or safety accidents, and avoid excessive impact on the atmospheric environment.
[0057] The top of the rectifying water wash tower 5 is connected to the rectifying water seal 6 through a pipeline.
[0058] The distillation water seal 6 is a device used to seal and prevent gas leakage during the distillation process. The gas is isolated in the form of a water seal, which can effectively prevent the gas from escaping from the system.
[0059] An emergency shut-off valve 14 is provided at the inlet of the distillation water seal 6. When the pressure of the distillation water seal 6 is abnormal, the emergency shut-off valve 14 is shut off.
[0060] A pipeline is connected to the top of the distillation water seal 6, and an emergency vent valve 15 is arranged on the pipeline. When an emergency occurs or the distillation vacuum pump stops, the oxygen content in the cracking furnace 7 is higher than 10%, and the outlet temperature of the cracking furnace 7 is lower than 600° C., the emergency vent valve 15 is opened and the air is vented through the pipeline on the emergency vent valve 15.
[0061] The cracking furnace 7 and the rectifying water seal 6 are connected to the burner of the cracking furnace 7 through a pipeline, and an emergency shut-off valve 16 is provided on the pipeline. The diketene tail gas enters the rectifying water seal 6 from the rectifying water washing tower 5 through a pipeline and is sent to the cracking furnace 7 for incineration and decomposition.
[0062] The exhaust of the distillation vacuum pump is the driving force for the tail gas to enter the cracking furnace 7. If the pump is tripped, the cracking furnace 7 has a safety risk of backfire, and the cracking furnace 7 is immediately cut off by the emergency cut-off valve 2 16. The emergency cut-off valve 2 16 is a regulating valve or a cut-off valve entering the cracking furnace 7. It is the last valve entering the cracking furnace 7 and is used for normal parking remote control. In the event of abnormal working conditions, it can also be remotely chained and cut off.
[0063] The cracking furnace 7 is equipped with an oxygen content analyzer. If the oxygen content in the cracking furnace 7 is too high, the risk of explosion and combustion will increase. Therefore, when the oxygen content analyzer detects that the oxygen content in the cracking furnace 7 exceeds the safety threshold (such as 10%), it is necessary to take immediate measures to reduce the oxygen content to ensure production safety. Releasing gas containing excess oxygen into the air through the top pipe of the distillation water seal 6 is an effective method to reduce the oxygen content in the system. This helps to reduce the formation of explosive mixtures and reduce the risk of fire and explosion.
[0064] The outlet temperature of the cracking furnace 7 is one of the important indicators reflecting the degree of cracking reaction. If the temperature is too low, it may mean that the cracking reaction is incomplete, affecting the quality and yield of the product. When the outlet temperature of the cracking furnace 7 is lower than 600°C, venting measures are taken. This helps to adjust the pressure and temperature in the system, promote the cracking reaction, and prevent side reactions or product quality problems caused by too low temperature.
[0065] The tail gas of diketene enters the distillation buffer tank 2 and the distillation oil tank 1 in sequence through pipelines, and is pumped into the distillation activated carbon tank 4 and the distillation water washing tower 5 in sequence through the distillation vacuum pump. Then the tail gas of the distillation vacuum pump enters the distillation water seal 6 through pipelines, and the tail gas of the vacuum pump in the distillation water seal 6 enters the cracking furnace 7 and is incinerated at a high temperature of 800°C in the cracking furnace 7.
[0066] The present invention realizes a low-oxygen process pipeline, and ensures the safety of incineration of tail gas under low-oxygen conditions. Compared with the unorganized emission gas absorbed and discharged by the original activated carbon adsorption tank and the distillation water washing tower 5, the present invention leads the tail gas to the distillation water seal 6, enters the special burner, and then enters the cracking furnace 7 for high-temperature incineration at 800°C, which not only solves the problem of tail gas reaching the standard, but also saves a certain amount of fuel, and provides a multi-stage production method and process and a recovery device in the production of diethylene ketone.
[0067] Example 2
[0068] like Figure 1 As shown, the present invention provides a process for recovering tail gas from a diketene distillation vacuum pump, comprising the steps of:
[0069] Step S1, during the operation of the distillation vacuum pump, the tail gas at the outlet enters the distillation activated carbon tank 4 through a pipeline, and the activated carbon adsorbs the tail gas;
[0070] Step S2, after the activated carbon absorbs the tail gas, it enters the distillation water washing tower 5 and absorbs the tail gas through normal temperature water;
[0071] Step S3, after being absorbed by normal temperature water in the distillation water washing tower 5, the tail gas of the distillation vacuum pump enters the distillation water seal 6 through the pipeline;
[0072] Step S4, after entering the special burner through the emergency shut-off valve 2, it enters the cracking furnace for combustion and decomposition.
[0073] The diameter of the pipeline between the distillation vacuum pump and the distillation water seal 6 is 159 mm.
[0074] The above technical features constitute the best embodiment of the present invention, which has strong adaptability and best implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the needs of different situations.
[0075] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.
Claims
1. A device for recovering tail gas from a diketene distillation vacuum pump, comprising a distillation kettle, wherein the material for producing diketene is in the distillation kettle, and characterized in that: It also includes a distillation buffer tank, a distillation oil tank, a distillation vacuum pump, a distillation activated carbon tank, a distillation water washing tower, a distillation water seal, and a cracking furnace. The distillation kettle is connected to the top of the distillation buffer tank through a pipeline, the distillation buffer tank is connected to the top of the distillation oil tank through a pipeline, the distillation oil tank is connected in series with the distillation vacuum pump through a pipeline, the distillation vacuum pump is connected to the distillation activated carbon tank through a pipeline, the distillation activated carbon tank is connected to the distillation water washing tower through a pipeline, the distillation water washing tower is connected to the distillation water seal through a pipeline, and the distillation water seal is connected to the cracking furnace through a pipeline.
2. The device according to claim 1, characterized in that The pressure in the distillation buffer tank is ≥-90Kpa.
3. The device according to claim 1, characterized in that The reaction temperature in the distillation oil tank is ≤18°C and the pressure is normal pressure.
4. The device according to claim 1, characterized in that The distillation oil tank is connected in series with two parallel distillation vacuum pumps through a pipeline, including distillation vacuum pump 1 and distillation vacuum pump 2. The inlet of distillation vacuum pump 1 is provided with inlet valve 1, and the outlet of distillation vacuum pump 1 is provided with outlet valve 1; the inlet of distillation vacuum pump 2 is provided with inlet valve 2, and the outlet of distillation vacuum pump 2 is provided with outlet valve 2.
5. The device according to claim 1, characterized in that An inlet valve three is arranged at the inlet of the distillation activated carbon tank.
6. The device according to claim 1, characterized in that The top of the distillation water washing tower is connected with a pipeline, and an emergency vent valve 1 is arranged on the pipeline.
7. The device according to claim 1, characterized in that An emergency shut-off valve is provided at the inlet of the distillation water seal.
8. The device according to claim 1, characterized in that A pipeline is connected to the top of the distillation water seal, and an emergency vent valve 2 is arranged on the pipeline.
9. The device according to claim 1, characterized in that The distillation water seal is connected to the burner of the cracking furnace through a pipeline, and an emergency shut-off valve 2 is arranged on the pipeline.
10. A process for recovering tail gas from a diketene distillation vacuum pump, characterized in that: Includes steps: Step S1, during the operation of the distillation vacuum pump, the tail gas at the outlet enters the distillation activated carbon tank through a pipeline, and the activated carbon adsorbs the tail gas; Step S2: After the activated carbon absorbs the tail gas, the tail gas from the distillation vacuum pump enters the distillation water washing tower and is absorbed by normal temperature water; Step S3, after being absorbed by water at room temperature, the tail gas of the distillation vacuum pump enters the distillation water seal through a pipeline; Step S4: After passing through the distillation water seal, the tail gas of the distillation vacuum pump enters the cracking furnace and is burned and decomposed at a high temperature above 800°C.