Skid-mounted octafluoropropane tail gas recovery treatment device and use method

Abstract

The invention belongs to the technical field of octafluoropropane rectification tail gas recovery treatment in the high-purity electronic special gas industry, and particularly relates to a skid-mounted octafluoropropane tail gas recovery treatment device and a use method. The device comprises a buffer tank, a catalytic reaction tower, a heat exchanger, a recycling unit, a plasma cracking unit and a tail gas treatment unit, the buffer tank is communicated with the catalytic reaction tower, the catalytic reaction tower is communicated with the heat exchanger, one end of the heat exchanger is communicated with the plasma cracking unit, the other end of the heat exchanger is communicated with the recycling unit, and the recycling unit is further communicated with the plasma cracking unit; and the plasma cracking unit is communicated with the tail gas recovery unit. According to the invention, recovery of octafluoropropane and the like is realized through two-stage catalytic reaction, and tail gas emission is reduced.

Description

Technical Field

[0001] This application belongs to the technical field of recovery and treatment of distillation tail gas of octafluoropropane in the high-purity electronic special gas industry, and specifically relates to a skid-mounted octafluoropropane tail gas recovery and treatment device and its use method. Background Art

[0002] Octafluoropropane is used as a plasma etching gas and a cleaning gas in semiconductor manufacturing. High requirements are placed on the impurity content and purity of the product, and generally the purity needs to reach more than 99.999% (5N). With the shrinking of the semiconductor manufacturing process, the purity requirements for octafluoropropane are also continuously increasing.

[0003] There are mainly three existing production routes for octafluoropropane. The first is a by-product of CF4 production. The impurity components in the by-product octafluoropropane separated by this process are complex, and it is difficult to purify high-purity electronic gas, which is not suitable for the semiconductor industry. The second scheme is the addition reaction of hexafluoropropene and fluorine gas to obtain octafluoropropane. In this process, 5%-20% of hexafluoropropene will polymerize to form perfluorinated long-chain heavy components such as perfluorohexane and perfluoropentane during the synthesis process, and hexafluoropropene will also form a ring to generate perfluorocyclopropane. The third scheme is the reaction of hexafluoropropene and metal fluoride to obtain octafluoropropane. Similar to the second scheme, it will also produce a relatively large amount of perfluorocyclopropane, perfluorohexane, perfluoropentane and other long-chain fluorocarbon compounds.

[0004] At present, the general method for the recovery and treatment of the tail gas of fluorocarbons is plasma cracking followed by alkali washing. Since there are more fluorocarbon heavy components generated during the synthesis of octafluoropropane, a large amount of fluorocarbon heavy components need to be discharged during the distillation process. It is necessary to design a plasma cracking tower with a huge load capacity, which has extremely high operating costs, a large discharge volume, and is prone to unstable discharge, resulting in unqualified tail gas indicators. In addition, such a large discharge of fluorocarbons causes great economic losses.

[0005] The Chinese utility model patent with the publication number CN220090988U discloses a production line for the recovery and utilization of fluorine-containing tail gas of lithium hexafluorophosphate. Specifically, it includes a tail gas treatment unit and a wastewater treatment unit. The tail gas treatment unit includes a primary alkali washing tower, a secondary alkali washing tower and a water washing tower. The upper part of the primary alkali washing tower and the secondary alkali washing tower is provided with a tail gas inlet, and the lower part is provided with a tail gas outlet. An ammonia water spraying device is arranged in the primary alkali washing tower and the secondary alkali washing tower. The washing liquid generated by washing the tail gas is pumped into the wastewater treatment unit. The tail gas treatment unit adopts the method of "two-stage ammonia water washing + one-stage water washing" for treatment, and the washing liquid is recycled. This is similar to the traditional method for the recovery and treatment of the tail gas of fluorocarbons, but it cannot solve the problem of more fluorocarbon heavy components generated during the synthesis of octafluoropropane in this application and the high treatment cost.

[0006] In summary, for the common tail gas in the prior art, it is usually removed by alkali washing, which has universality. However, for the problem of high treatment cost due to the large amount of fluorocarbon heavy components generated in the synthesis process of octafluoropropane, simply through the cracking gap, the problems of high cost and unqualified tail gas treatment polluting the environment cannot be solved. Therefore, it is urgent to propose a skid-mounted octafluoropropane tail gas recovery and treatment device and its use method to solve the problems existing in the prior art. Summary of the Invention

[0007] In the prior art, during the synthesis process of octafluoropropane, there are a large number of fluorocarbon heavy components generated. During the rectification process, a large amount of fluorocarbon heavy components need to be discharged. It is necessary to design a plasma cracking tower with a huge load capacity, which has high operating costs and large emissions. At the same time, it is easy to cause unstable emissions, resulting in unqualified tail gas indicators. In addition, such a large emission of fluorocarbon compounds causes significant economic losses. Therefore, this application proposes a skid-mounted octafluoropropane tail gas recovery and treatment device and its use method.

[0008] The technical solution of this application is as follows:

[0009] On the one hand, this application provides a skid-mounted octafluoropropane tail gas recovery and treatment device, including a buffer tank, a catalytic reaction tower, a heat exchanger, a recycling unit, a plasma cracking unit, and a tail gas treatment unit; the upper and lower parts of the buffer tank are both connected to the upper part of the catalytic reaction tower, the lower part of the catalytic reaction tower is connected to the side of the heat exchanger, one end of the heat exchanger is connected to the plasma cracking unit, the other end is connected to the recycling unit, and the recycling unit is also connected to the plasma cracking unit; the plasma cracking unit is connected to the tail gas recovery unit. Preferably, the recycling unit includes a recovery tank and a condensation column arranged on the recovery tank; the plasma cracking unit includes a plasma cracking tower and a carrier gas pump, and the lower part of the plasma cracking tower is connected to the carrier gas pump; the tail gas treatment unit includes a primary alkali washing tower and a secondary alkali washing tower, and the upper part of the primary alkali washing tower is connected to the lower part of the secondary alkali washing tower.

[0010] Preferably, the upper part of the condensation column and the lower part of the heat exchanger are both connected to the side of the plasma cracking tower; the upper part of the plasma cracking tower is connected to the lower part of the primary alkali washing tower.

[0011] Preferably, the heat exchanger is connected to the side of the condensation column of the recycling unit.

[0012] Preferably, the upper part of the buffer tank is provided with a gas outlet, and the gas outlet is connected to the upper part of the catalytic reaction tower; the lower part of the buffer tank is provided with a liquid outlet, and the liquid outlet is connected to the upper part of the catalytic reaction tower; a flow meter is also provided between the liquid outlet and the catalytic reaction tower.

[0013] Preferably, a light component inlet is provided above the side wall of the buffer tank, and a heavy component inlet is provided below the side wall of the buffer tank. A liquid level gauge is provided on the side wall of the buffer tank.

[0014] On the other hand, the present application provides a method for using a skid-mounted octafluoropropane tail gas recovery and treatment device, which is characterized by including the following steps:

[0015] Step S1. Pretreatment of the catalytic reaction tower: The catalytic reaction tower is filled with a molecular sieve catalyst. The catalytic reaction tower is purged with an inert gas at 300 - 600 °C for 2 - 12 h, and finally the temperature of the catalytic reaction tower is reduced to 150 - 250 °C. The catalytic reaction temperature of the subsequent catalytic reaction tower is 150 - 250 °C;

[0016] Step S2. Catalytic reaction: The light component gas discharged from the octafluoropropane de-lighting tower and the liquid heavy component of the de-heavy tower enter the buffer tank and then enter the catalytic reaction tower;

[0017] Step S3. Cooling separation and plasma cracking: The material coming out of the catalytic reaction tower enters the heat exchanger. Under the action of the heat exchanger, the light components of gaseous octafluoropropane, hexafluoropropene and other fluorocarbons enter the recovery unit, and the unreacted heavy components are liquefied and enter the plasma cracking tower for cracking reaction; Under the action of the condensation column in the recovery unit, octafluoropropane and hexafluoropropene are condensed and enter the recovery tank, and other fluorocarbons enter the plasma cracking tower for cracking reaction in the form of gas phase;

[0018] Step S4. Caustic washing treatment: In the plasma cracking tower, the CO2 and HF gases generated by the cracking reaction are discharged after two-stage caustic washing treatment.

[0019] Preferably, the preparation method of the molecular sieve catalyst in the step S1 is: The molecular sieve catalyst precursor is loaded on the surface of a metal θ-ring or Pall ring carrier by the impregnation method, and then placed in a roasting treatment at 400 - 600 °C for 10 h and then naturally cooled to obtain the molecular sieve catalyst.

[0020] Preferably, the temperature of the heat exchanger is controlled at -20 - 20 °C in the step S3; the temperature of the condensation column is -90 - -60 °C, and the temperature of the recovery tank is -60 - -40 °C.

[0021] Preferably, the cracking temperature in the step S3 is 450 - 550 °C

[0023] The beneficial effects of the present application:

[0024] (1) This application recycles a large amount of deweighted tail gas. By designing a catalytic reaction tower and a plasma cracking tower, the heavy components and light components in the octafluoropropane tail gas are first preliminarily catalytically cracked in the catalytic reaction tower. After passing through the heat exchanger, the uncatalyzed heavy components are liquefied and enter the plasma cracking tower, and the gaseous components that have undergone catalytic reactions pass through the condensation column of the recycling unit. Under the action of the condensation column in the recycling unit, octafluoropropane and hexafluoropropylene are condensed and enter the recycling tank, and other fluorocarbons enter the plasma cracking tower for cracking reactions in gaseous form. This not only reduces the emission of materials but also increases the yield of the octafluoropropane process and reduces the production cost of octafluoropropane.

[0025] (2) Under the action of the plasma cracking tower in this application, the materials entering the plasma cracking tower are cracked to produce CO2 and HF gases, which are subjected to two-stage alkali washing, greatly reducing the emission of three-waste tail gas and reducing the emission of CO2, etc., in line with the development of the green economy.

[0026] (3) The modular advantages brought by the skid-mounted design of this application facilitate transportation and installation, are applicable to different sites, reduce on-site construction time and costs, and through a series of emission reduction methods, make the three-waste treatment device operate more stably, reduce the abnormal risk, and ensure the up-to-standard emission of the tail gas.

[0027] (4) This application recycles a large amount of deweighted tail gas, reduces the scale of the three-waste device, reduces the load of the plasma cracking device, and greatly saves operation and maintenance costs. Brief Description of the Drawings

[0028] Appendix Figure 1 This is a drawing of a skid-mounted octafluoropropane tail gas recovery and treatment device of this application.

[0029] Description of the Drawing Reference Numerals: 1, buffer tank; 101, liquid level gauge; 102, light component inlet; 103, heavy component inlet; 104, flow meter; 2, catalytic reaction tower; 3, heat exchanger; 4, recycling tank; 5, condensation column; 6, plasma cracking tower; 7, carrier gas pump; 8, first-stage alkali washing tower; 9, second-stage alkali washing tower; 10, regulating valve. Detailed Embodiments

[0030] To further elaborate on the technical means and effects adopted by this application to achieve the intended invention purpose, the following, in combination with preferred embodiments, details the specific implementation manners, structures, features, and their effects according to this application as follows.

[0031] Equipment Example

[0032] As shown in the appendix Figure 1 shown, a skid-mounted octafluoropropane tail gas recovery and treatment device is provided as follows:

[0033] It includes a buffer tank 1, a catalytic reaction tower 2, a heat exchanger 3, a recycling unit, a plasma cracking unit and an exhaust gas treatment unit, which are modularly integrated by pipelines on a skid-mounted base, reducing the on-site installation complexity and being applicable to mobile or distributed production scenarios.

[0034] The upper part of the buffer tank 1 is provided with a gas outlet, the lower part is provided with a liquid outlet, the upper side wall is provided with a light component inlet 102, the lower side wall is provided with a heavy component inlet 103, and a liquid level gauge 101 is installed on the side wall. The light component inlet 102 is used to receive the light component gas extracted from the light component removal tower in the continuous distillation of octafluoropropane, the heavy component inlet 103 is used to receive the liquid heavy component extracted from the heavy component removal tower in the continuous distillation of octafluoropropane, and the liquid level gauge 101 monitors the liquid level in the tank in real time.

[0035] The catalytic reaction tower 2 is a packed vertical reaction tower filled with molecular sieve catalysts. The molecular sieve catalysts are impregnated in metal rings or Pall rings and calcined before use, having a large specific surface area and abundant active sites, which improves the conversion efficiency. There are two feed inlets at the upper part of the catalytic reaction tower 2. One of the feed inlets is connected to the gas outlet at the upper part of the buffer tank 1 through a pipeline for introducing gaseous light components, and a control valve 10 is also provided on the pipeline where the control valve 10 can be a self-acting control valve to automatically adjust the pressure of the buffer tank 1 by controlling the feed. The other feed inlet is connected to the liquid outlet at the lower part of the buffer tank 1 through a pipeline for introducing liquid heavy components, and a flow meter 104 and a control valve 10 are also provided on the pipeline where the control valve 10 can be a pneumatic control valve. The control valve 10 and the flow meter 104 are used in combination to control the flow rate of the heavy components entering the catalytic reaction tower 2 to avoid the imbalance of the reaction material ratio.

[0036] The lower part of the catalytic reaction tower 2 is provided with a material outlet, and the material outlet is connected to the lower part of the heat exchanger 3. The heat exchanger 3 is a shell-and-tube heat exchanger. The upper part of the heat exchanger 3 is connected to the recycling unit through a pipeline, and a control valve 10 is provided on the pipeline for adjusting the intake air volume. The lower part of the heat exchanger 3 is connected to the plasma cracking unit through a pipeline, and a control valve 10 is provided on the pipeline for adjusting the feed rate. The heat exchanger 3 cools the reaction products through temperature control to separate gaseous light components (C3F8, C3F6) from the unreacted liquid heavy components.

[0037] The recycling unit includes a recycling tank 4 and a condensation column 5 located above the recycling tank 4 and connected to the recycling tank 4. The side part of the condensation column 5 is connected to the upper part of the heat exchanger 3. The upper part of the condensation column 5 is connected to the side part of the plasma cracking tower 6 through a pipeline, and a control valve 10 is provided on the pipeline. The inside of the condensation column 5 is a shell-and-tube heat exchange, and fins are provided outside the tubes. The condensation column 5 liquefies and recovers gaseous C3F8 and C3F6 into the recycling tank 4, and the uncondensed gas enters the plasma cracking tower 6 to achieve high-purity recovery of fluorocarbon compounds.

[0038] The plasma cracking unit includes a plasma cracking tower 6 and a carrier gas pump 7. The lower part of the plasma cracking tower 6 is connected to the carrier gas pump 7 through a pipeline, and a regulating valve 10 is provided on the pipeline. The carrier gas pump 7 promotes the circulation of cracking gas and improves the reaction efficiency.

[0039] The tail gas treatment unit includes a first-stage caustic scrubbing tower 8 and a second-stage caustic scrubbing tower 9 connected in series. The lower part of the first-stage caustic scrubbing tower 8 is connected to the upper part of the plasma cracking tower 6 through a pipeline, and a regulating valve 10 for controlling the flow rate is provided on the pipeline. The upper part of the first-stage caustic scrubbing tower 8 is connected to the lower part of the second-stage caustic scrubbing tower 9 through a pipeline, and a regulating valve 10 for controlling the flow rate is provided on the pipeline. Two-stage caustic scrubbing is carried out to meet the emission standards.

[0040] Principle of equipment embodiment:

[0041] The light component gas extracted from the light component tower in the continuous rectification of octafluoropropane enters the buffer tank 1 through the light component inlet 102 on the buffer tank 1, and the liquid heavy component extracted from the heavy component tower in the continuous rectification of octafluoropropane enters the buffer tank 1 through the heavy component inlet 103. After buffering in the buffer tank 1, the gas light component enters the catalytic reaction tower 2 through the gas outlet of the buffer tank 1, and the liquid heavy component enters the catalytic reaction tower 2 through the liquid outlet of the buffer tank 1. Under the action of the catalyst in the catalytic reaction tower 2, the heavy component and the light component undergo a catalytic cracking reaction.

[0042] The reacted material is discharged from the lower part of the catalytic reaction tower 2 and enters the heat exchanger 3 for heat exchange. Among them, the light component is extracted from the upper part of the heat exchanger 3 and enters the condensation column 5. Under the action of the condensation column 5, gaseous C3F8 and C3F6 are liquefied and recovered into the recovery tank 4, and the gaseous substances enter the plasma cracking tower 6 along the upper part of the condensation column 5; the unreacted heavy component flows out from the lower part of the heat exchanger 3 under the action of the heat exchanger 3 and enters the plasma cracking tower 6, and a cracking reaction occurs in the plasma cracking tower 6 to generate CO2 and HF. The lower part of the plasma cracking tower 6 is connected to the carrier gas pump 7, which is used to accelerate the cycle and improve the cracking efficiency.

[0043] The material generated by the reaction in the plasma cracking tower 6 removes more CO2 and HF through the first-stage caustic scrubbing tower 8, and then passes through the second-stage caustic scrubbing tower 9 for further removal, and finally meets the emission standards.

[0044] Method embodiment 1

[0045] Step S1. Pretreatment of the catalytic reaction tower 2:

[0046] The catalytic reaction tower 2 is filled with a molecular sieve catalyst. Helium is used to purge the catalytic reaction tower 2 at 450 °C for 8 h, the gas flow rate is 20 m / s, and finally the catalytic reaction tower 2 is cooled to 200 °C. The catalytic reaction temperature of the subsequent catalytic reaction tower 2 is 180 °C;

[0047] The preparation method of the molecular sieve catalyst is as follows: the molecular sieve catalyst precursor is loaded on the surface of a metal theta ring or Pall ring carrier by the impregnation method, and then placed in a muffle furnace at 500 °C for roasting for 10 h and then naturally cooled to obtain the molecular sieve catalyst.

[0048] Step S2. Catalytic reaction:

[0049] The light component gas discharged from the octafluoropropane light removal tower and the heavy component liquid of the heavy removal tower enter the buffer tank 1 and then enter the catalytic reaction tower 2;

[0050] Step S3. Cooling separation and plasma cracking:

[0051] The material coming out of the catalytic reaction tower 2 enters the heat exchanger 3. Under the action of the heat exchanger 3, the gaseous octafluoropropane, hexafluoropropene and other light components of fluorocarbon compounds enter the recovery unit, and the unreacted heavy components are liquefied and enter the plasma cracking tower 6 for cracking reaction; under the action of the condensation column 5 in the recovery unit, octafluoropropane and hexafluoropropene are condensed and enter the recovery tank 4, and other fluorocarbon compounds enter the plasma cracking tower 6 for cracking reaction in gaseous form; the temperature of the heat exchanger 3 is controlled at 0 °C; the temperature of the condensation column 5 is -70 °C, the temperature of the recovery tank 4 is -50 °C, and the temperature of the plasma cracking is 500 °C.

[0052] Step S4. Caustic washing treatment:

[0053] In the plasma cracking tower 6, the CO2 and HF gases generated by the cracking reaction are discharged after two-stage caustic washing treatment. The caustic washing liquid is sodium hydroxide with a concentration of 5 moL / L. After detection, it meets the relevant regulations for tail gas emissions in GB 16297-1996.

[0054] Method Example 2

[0055] Step S1. Pretreatment of the catalytic reaction tower 2:

[0056] The catalytic reaction tower 2 is filled with a molecular sieve catalyst. Helium is used to purge the catalytic reaction tower 2 at 600 °C for 2 h, and the gas flow rate is 20 m / s. Finally, the catalytic reaction tower 2 is cooled to 250 °C, and the catalytic reaction temperature of the subsequent catalytic reaction tower 2 is 150 °C;

[0057] The preparation method of the molecular sieve catalyst is as follows: the molecular sieve catalyst precursor is loaded on the surface of a metal theta ring or Pall ring carrier by the impregnation method, and then placed in a muffle furnace at 600 °C for roasting for 10 h and then naturally cooled to obtain the molecular sieve catalyst.

[0058] Step S2. Catalytic reaction:

[0059] The light component gas discharged from the octafluoropropane light removal tower and the heavy component liquid of the heavy removal tower enter the buffer tank 1 and then enter the catalytic reaction tower 2;

[0060] Step S3. Cooling separation and plasma pyrolysis:

[0061] The material coming out of the catalytic reaction tower 2 enters the heat exchanger 3. Under the action of the heat exchanger 3, the light components of gaseous octafluoropropane, hexafluoropropene and other fluorocarbons enter the recovery unit, and the unreacted heavy components are liquefied and enter the plasma pyrolysis tower 6 for pyrolysis reaction; under the action of the condensation column 5 in the recovery unit, octafluoropropane and hexafluoropropene are condensed and enter the recovery tank 4, and other fluorocarbons enter the plasma pyrolysis tower 6 for pyrolysis reaction in gaseous form; the temperature of the heat exchanger 3 is controlled at -20°C; the temperature of the condensation column 5 is -60°C, the temperature of the recovery tank 4 is -60°C, and the temperature of plasma pyrolysis is 550°C.

[0062] Step S4. Caustic washing treatment:

[0063] In the plasma pyrolysis tower 6, the CO2 and HF gases generated by the pyrolysis reaction are discharged after two-stage caustic washing treatment. The caustic washing liquid is sodium hydroxide with a concentration of 5 moL / L. After detection, it meets the relevant regulations for tail gas emissions in GB 16297-1996.

[0064] Method Example 3

[0065] Step S1. Pretreatment of the catalytic reaction tower 2:

[0066] The catalytic reaction tower 2 is filled with a molecular sieve catalyst. Helium is used to purge the catalytic reaction tower 2 at 300°C for 12 h with a gas flow rate of 20 m / s. Finally, the catalytic reaction tower 2 is cooled to 150°C, and the catalytic reaction temperature of the subsequent catalytic reaction tower 2 is 250°C;

[0067] The preparation method of the molecular sieve catalyst is: the molecular sieve catalyst precursor is loaded on the surface of a metal theta ring or Pall ring carrier by the impregnation method, and then placed in a calcination treatment at 400°C for 10 h and naturally cooled to obtain the molecular sieve catalyst.

[0068] Step S2. Catalytic reaction:

[0069] The light component gas discharged from the octafluoropropane light component tower and the heavy component liquid of the heavy component tower enter the buffer tank 1 and then enter the catalytic reaction tower 2;

[0070] Step S3. Cooling separation and plasma pyrolysis:

[0071] The material exiting from the catalytic reaction tower 2 enters the heat exchanger 3. Under the action of the heat exchanger 3, the gaseous octafluoropropane, hexafluoropropene and other light components of fluorocarbons enter the recovery unit, and the unreacted heavy components are liquefied and enter the plasma cracking tower 6 for cracking reaction; under the action of the condensation column 5 in the recovery unit, octafluoropropane and hexafluoropropene are condensed and enter the recovery tank 4, and other fluorocarbons enter the plasma cracking tower 6 for cracking reaction in gaseous form; the temperature of the heat exchanger 3 is controlled at 20 °C; the temperature of the condensation column 5 is -90 °C, the temperature of the recovery tank 4 is -40 °C, and the temperature of the plasma cracking is 450 °C.

[0072] Step S4. Alkaline washing treatment:

[0073] In the plasma cracking tower 6, the CO2 and HF gases generated by the cracking reaction are discharged after two-stage alkaline washing treatment. The alkaline washing liquid is sodium hydroxide with a concentration of 5 moL / L. After detection, it complies with the relevant regulations on tail gas emissions in GB 16297-1996.

[0074] The above are only the preferred embodiments of the present application and do not impose any form of limitation on the present application. Although the present application has been disclosed above with the preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the disclosed technical content without departing from the technical solution scope of the present application. However, any modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still fall within the scope of the technical solution of the present application.

Claims

1. A skid-mounted octafluoropropane tail gas recovery and treatment device, characterized in that, It includes a buffer tank (1), a catalytic reaction tower (2), a heat exchanger (3), a recycling unit, a plasma cracking unit and a tail gas treatment unit; the upper and lower parts of the buffer tank (1) are both connected to the upper part of the catalytic reaction tower (2), the lower part of the catalytic reaction tower (2) is connected to the side part of the heat exchanger (3), one end of the heat exchanger (3) is connected to the plasma cracking unit, the other end is connected to the recycling unit, and the recycling unit is also connected to the plasma cracking unit; the plasma cracking unit is connected to the tail gas recycling unit.

2. The skid-mounted octafluoropropane tail gas recovery and treatment device according to claim 1, characterized in that, The recycling unit includes a recycling tank (4) and a condensation column (5) arranged on the recycling tank (4); the plasma cracking unit includes a plasma cracking tower (6) and a carrier gas pump (7), and the lower part of the plasma cracking tower (6) is connected to the carrier gas pump (7); the tail gas treatment unit includes a primary caustic scrubber (8) and a secondary caustic scrubber (9), and the upper part of the primary caustic scrubber (8) is connected to the lower part of the secondary caustic scrubber (9).

3. The skid-mounted octafluoropropane tail gas recovery and treatment device according to claim 2, characterized in that, The upper part of the condensation column (5) and the lower part of the heat exchanger (3) are both connected to the side part of the plasma cracking tower (6); the upper part of the plasma cracking tower (6) is connected to the lower part of the primary caustic scrubber (8).

4. A skid-mounted octafluoropropane tail gas recovery and treatment device according to claim 2, characterized in that, The heat exchanger (3) is connected to the side part of the condensation column (5) of the recycling unit.

5. The skid-mounted octafluoropropane tail gas recovery and treatment device according to claim 1, characterized in that, The upper part of the buffer tank (1) is provided with a gas outlet, and the gas outlet is connected to the upper part of the catalytic reaction tower (2); the lower part of the buffer tank (1) is provided with a liquid outlet, and the liquid outlet is connected to the upper part of the catalytic reaction tower (2); a flow meter (104) is also provided between the liquid outlet and the catalytic reaction tower (2).

6. The skid-mounted octafluoropropane tail gas recovery and treatment device according to claim 1, characterized in that, The upper part of the side wall of the buffer tank (1) is provided with a light component inlet (102), the lower part is provided with a heavy component inlet (103), and the side wall of the buffer tank (1) is provided with a liquid level gauge (101).

7. The usage method of a skid-mounted octafluoropropane tail gas recovery and treatment device according to any one of claims 1 to 6, characterized in that, It includes the following steps: Step S1. Pretreatment of the catalytic reaction tower (2): The catalytic reaction tower (2) is filled with a molecular sieve catalyst, and the catalytic reaction tower (2) is purged with an inert gas at 300 - 600 °C for 2 - 12 h, and finally the catalytic reaction tower (2) is cooled to 150 - 250 °C. The subsequent catalytic reaction temperature of the catalytic reaction tower (2) is 150 - 250 °C; Step S2. Catalytic reaction: The light component gas discharged from the octafluoropropane de-lighting tower and the heavy component liquid from the de-heavy tower enter the buffer tank (1) and then enter the catalytic reaction tower (2); Step S3. Cooling separation and plasma cracking: The material coming out of the catalytic reaction tower (2) enters the heat exchanger (3). Under the action of the heat exchanger (3), the light components of gaseous octafluoropropane, hexafluoropropene and other fluorocarbons enter the recycling unit, and the unreacted heavy components are liquefied and enter the plasma cracking tower (6) for cracking reaction; under the action of the condensation column (5) of the recycling unit, octafluoropropane and hexafluoropropene are condensed and enter the recycling tank (4), and other fluorocarbons enter the plasma cracking tower (6) for cracking reaction in gaseous form; Step S4. Alkaline washing treatment: In the plasma cracking tower (6), the CO2 and HF gases generated by the cracking reaction are discharged after two-stage alkaline washing treatment.

8. The usage method of a skid-mounted octafluoropropane tail gas recovery and treatment device according to claim 7, characterized in that The preparation method of the molecular sieve catalyst in the step S1 is as follows: The molecular sieve catalyst precursor is loaded on the surface of a metal θ-ring or Pall ring carrier by the impregnation method, and then placed in a calcination treatment at 400-600 °C for 10 h and then naturally cooled to obtain the molecular sieve catalyst.

9. The method for using a skid-mounted octafluoropropane tail gas recovery and treatment device according to claim 7, characterized in that, In the step S3, the temperature of the heat exchanger (3) is controlled at -20 to 20 °C; the temperature of the condensation column (5) is -90 to -60 °C, and the temperature of the recovery tank (4) is -60 to -40 °C.

10. The usage method of a skid-mounted octafluoropropane tail gas recovery and treatment device according to claim 7, characterized in that, In the step S3, the cracking temperature is 450-550 °C.

Images