Reaction preparation method and preparation device for high-purity difluoroethane

Abstract

The invention provides a reaction preparation device for high-purity difluoroethane. An acetylene water ring pump (1) is connected with a finished product storage tank (21) sequentially through an acetylene freezing dehydrator (2), an acetylene cryogenic dehydrator (3), a dryer I (4), a fluorination reactor (5), a separation tower (11), a separation tower condenser (12), a water washing tower (13), an alkaline washing tower (14), a drying tower II (15), a centrifugal gas compressor (16), a gas condenser (17), a degassing tower (18), a rectifying tower (19) and an efficient dryer III (20). Acetylene gas, hydrogen fluoride and a catalyst enter a separation tower (11) from the upper part of a fluorination reactor (5), impurities in the crude product are removed through a separation tower condenser (12), and then the crude product is sent to a degassing tower to remove acetylene in a compression condensation mode; and refining the heavy component in a rectifying tower (19) to obtain a difluoroethane finished product, and drying and dehydrating to obtain high-purity difluoroethane.

Description

Technical Field

[0001] The present invention belongs to the technical field of difluoroethane production, and relates to a method for preparing high-purity difluoroethane by reaction and a preparation device therefor. Background Art

[0002] Difluoroethane is an important product in the organic fluorine industry. It is a colorless gas with a faint odor at room temperature, and its boiling point is -24.7°C. It belongs to low-toxic chemicals. It has an anesthetic effect at high concentrations, is flammable, and will react violently with strong oxidants. The ozone depletion potential (ODP) of difluoroethane is 0, and the global warming potential (GWP) is 0.03. As a substitute for CFCs, it can be directly used instead of F12, or a mixed refrigerant composed of difluoroethane can be used to replace existing industrial refrigerants, such as R401A, R401B, R401C, R405A, R411A, R411B, etc. Currently, difluoroethane is prepared by a liquid-phase fluorination method using untreated acetylene and anhydrous hydrogen fluoride. The reaction process of this method is not sufficient, resulting in poor reaction selectivity. The device used in the preparation process will also generate a lot of impurities, such as acetylene, vinyl fluoride, non-condensable gases such as nitrogen, etc., resulting in poor production efficiency and conversion rate. At the same time, the quality of the prepared difluoroethane is also relatively poor. Summary of the Invention

[0003] The present invention provides a method for preparing high-purity difluoroethane by reaction and a preparation device therefor, which can improve the reaction selectivity and conversion rate of preparing high-purity difluoroethane.

[0004] The present invention adopts the following technical solutions: A method for preparing high-purity difluoroethane by reaction, which comprises the following steps: Step 1: First, pre-treat the raw material acetylene. Feed the raw material acetylene into an acetylene water-ring pump, and then discharge it successively into an acetylene refrigeration dehydrator and an acetylene deep refrigeration dehydrator for dehydration through the outlet of the acetylene water-ring pump. After dehydration is completed, it enters a dryer I for drying treatment to obtain acetylene gas with qualified water content. The water content of the qualified acetylene gas is controlled at 5 - 10 ppm; Step 2: Feed hydrogen fluoride liquid into the liquid inlet Ⅰ at the upper part of the fluorination reactor, and feed the dehydrated acetylene gas into the fluorination reactor through the gas inlet Ⅱ at the upper part of the fluorination reactor. Then, convey it to the gas distributor at the bottom of the fluorination reactor. Utilize the bubbling effect of acetylene gas in the gas distributor to achieve full contact and reaction. Next, add the catalyst fluorosulfonic acid into the fluorination reactor through the inlet Ⅲ at the upper part of the fluorination reactor. After the acetylene gas, hydrogen fluoride liquid, and catalyst are fully mixed and reacted in the fluorination reactor, a gas-phase mixture is obtained. The gas-phase mixture then enters the separation tower through the discharge port on the side of the fluorination reactor, pipeline Ⅰ, and the feed port on the side of the separation tower in sequence for separation. The gas-phase mixture includes low-boiling vinyl fluoride and crude difluoroethane. The low-boiling vinyl fluoride and crude difluoroethane enter the separation tower filled with packing together. The condenser of the separation tower uses -15°C chilled brine for separation. Then, the separated vinyl fluoride liquid is refluxed back to the fluorination reactor through the pipeline Ⅱ connected to the bottom of the separation tower, so that the separated vinyl fluoride continues to react in the fluorination reactor. The crude difluoroethane is discharged from the top of the separation tower. The content of the crude difluoroethane after separation by the separation tower can reach 95 - 98%. Step 3: Feed the crude product after separation by the separation tower into the water washing tower, alkali washing tower, and drying tower Ⅱ through the first condensation of the condenser of the separation tower to remove impurities in the crude product. Step 4: Then, compress the crude product after removing impurities through a centrifugal gas compressor and condense it through a gas condenser. Then, send it to a degassing tower to remove the remaining impurities, and finally send it to a rectification tower for rectification to produce difluoroethane finished product. The difluoroethane finished product is dried and dehydrated through a high-efficiency dryer Ⅲ to obtain high-purity difluoroethane, and the high-purity difluoroethane is sent to the finished product storage tank.

[0005] Furthermore, in Step 1, the refrigerating liquid of the acetylene freezing dehydrator uses 5°C chilled brine, and the refrigerating liquid of the acetylene deep cooling dehydrator uses -15°C chilled brine for acetylene.

[0006] Furthermore, in Step 2, the feed pipe Ⅰ for acetylene gas, the feed pipe Ⅱ for hydrogen fluoride liquid, and the feed pipe Ⅲ for fluorosulfonic acid are respectively inserted into the interior of the fluorination reactor for feeding. Among them, acetylene gas obtains acetylene gas bubbling through the gas distributor. The fluorination reactor and the separation tower are fed or discharged through a gas-phase pipeline and a liquid-phase pipeline, forming a new reaction type that combines reaction and rectification. The separation tower is a packed tower, and there are 5 sections of packing distributed from top to bottom in the separation tower. This can enable the full contact of the mixture in the fluorination reactor and separate difluoroethane. In Step 2, the temperature of the full mixing and reaction in the fluorination reactor is controlled at 30 - 45°C, the reaction pressure is controlled at 0.2 - 0.3 MPa, and the molar flow ratio of acetylene to hydrogen fluoride is 1:2.1 - 2.8.

[0007] Furthermore, the top temperature of the separation column in step three is controlled at -12 - 5°C.

[0008] Furthermore, the impurities removed by the degassing column in step four include acetylene, vinyl fluoride, and nitrogen. The pressure of the degassing column is controlled at 0.95 - 1.05 MPa, the top temperature is controlled at 35 - 40°C, the light component removal amount is controlled at 0.1 - 0.3 kg / h, the pressure of the rectification column is controlled at 0.55 - 0.8 MPa, the top temperature of the rectification column is controlled at 30 - 35°C, the reflux ratio is controlled between 3 - 5, and the purity after rectification in the rectification column reaches 99.95%. The desiccant in the high - efficiency dryer III is molecular sieve or calcium chloride, where the molecular sieve is 4A° molecular sieve, 5A° molecular sieve, or special molecular sieve for refrigerant dehydration; the mesh number is 10 - 30 mesh. Finally, the high - purity difluoroethane prepared after high - efficiency drying has a purity of 99.99%.

[0009] The present invention also discloses a reaction preparation device for high - purity difluoroethane, which includes an acetylene water - ring pump, an acetylene freezing dehydrator, an acetylene deep - cooling dehydrator, a dryer I, a fluorination reactor, a separation column, a water - washing tower, an alkali - washing tower, a dryer III, a centrifugal gas compressor, a gas condenser, a degassing column, a rectification column, a high - efficiency dryer III, and a finished product storage tank. The outlet of the acetylene water - ring pump is sequentially connected to the gas inlet II at the upper part of the fluorination reactor through the acetylene freezing dehydrator, the acetylene deep - cooling dehydrator, and the dryer I. There are also a liquid inlet I and an inlet III at the upper part of the fluorination reactor. There is a gas distributor at the bottom of the fluorination reactor. The discharge port on the side of the fluorination reactor is connected to the feed port on the side of the separation column through pipeline I. The reflux port at the bottom of the separation column is connected to the reflux port on the side of the fluorination reactor through pipeline II. The gas outlet at the top of the separation column is connected to a separation column condenser, and the separation column condenser is sequentially connected to the side inlet of the degassing column through the water - washing tower, the alkali - washing tower, the dryer II, the centrifugal gas compressor, and the gas condenser. The bottom outlet of the degassing column is connected to the feed port of the rectification column, and the discharge port of the rectification column is connected to the finished product storage tank through the high - efficiency dryer III.

[0010] Furthermore, the dryer I is set as a molecular sieve dryer, and the molecular sieve of the molecular sieve dryer is 4A° molecular sieve, 5A° molecular sieve, or dehydration molecular sieve; the dryer II is set as a silica gel dryer, and the desiccant in the silica gel dryer is silica gel, which is coarse - mesh silica gel or microporous silica gel, and the mesh number of the silica gel is 50 - 150 mesh or microporous silica gel.

[0011] Furthermore, the feed pipe I inserted into the liquid inlet I extends into the fluorination reactor, the feed pipe II inserted into the gas inlet II extends into the fluorination reactor, and the feed pipe III inserted into the inlet III extends to the bottom of the fluorination reactor and is connected to the gas distributor.

[0012] Furthermore, the separation column is arranged as a packed column, and a number of packings are placed vertically therein from top to bottom. The packings are stainless steel Pall rings or Intalox saddles.

[0013] Furthermore, the high-efficiency dryer III is arranged as a molecular dryer. The desiccant of the molecular dryer is molecular sieve, and the mesh number of the molecular sieve is 10 - 30 meshes. The molecular sieve is 4A° molecular sieve, 5A° molecular sieve or special molecular sieve for refrigerant dehydration.

[0014] The present invention has the following beneficial effects: The method and its preparation device of the present invention adopt the combination of a fluorination reactor and a separation column. Acetylene gas, hydrogen fluoride and a catalyst enter the top of the separation column from the upper part of the fluorination reactor. The crude product at the top of the separation column removes impurities in the crude product through the separation column condenser; then, by using the compression and condensation method, the crude product is sent to a degassing column to remove acetylene; the heavy components go to a rectification column to refine the finished product of difluoroethane, and then it is dried and dehydrated to obtain high-purity difluoroethane with a purity that can reach 99.99%. This can greatly promote the gas-liquid mixing, fully react, and make the acetylene distribution uniform, with a fast reaction rate, a high conversion rate in the same reaction time, an improved selectivity, and a high production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0016] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The following will elaborate on the preferred embodiments of the present invention in conjunction with the drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0018] In Figure 1In this invention, a preparation device for highly pure difluoroethane is provided, which includes an acetylene water ring pump 1, an acetylene freezing dehydrator 2, an acetylene deep cooling dehydrator 3, a dryer I 4, a fluorination reactor 5, a separation tower 11, a water washing tower 13, an alkali washing tower 14, a drying tower III 15, a centrifugal gas compressor 16, a gas condenser 17, a degassing tower 18, a rectifying tower 19, a high-efficiency dryer III 20 and a finished product storage tank 21. The outlet of the acetylene water ring pump 1 is sequentially connected to the gas inlet II 7 at the upper part of the fluorination reactor 5 through the acetylene freezing dehydrator 2, the acetylene deep cooling dehydrator 3 and the dryer I 4. At the upper part of the fluorination reactor 5, there are also a liquid inlet I 6 and an inlet III 23. At the bottom of the fluorination reactor 5, there is a gas distributor 8. The discharge port 9 on the side of the fluorination reactor 5 is connected to the feed port 22 on the side of the separation tower 11 through a pipeline I 10. The reflux port at the bottom of the separation tower 11 is connected to the reflux port on the side of the fluorination reactor 5 through a pipeline II 12. The gas outlet at the top of the separation tower 11 is connected to a separation tower condenser 12. The separation tower condenser 12 is sequentially connected to the side inlet of the degassing tower 18 through the water washing tower 13, the alkali washing tower 14, the drying tower II 15, the centrifugal gas compressor 16 and the gas condenser 17. The bottom outlet of the degassing tower is connected to the feed port of the rectifying tower 19. The discharge port of the rectifying tower 19 is connected to the finished product storage tank 21 through the high-efficiency dryer III 20. In this embodiment, the dryer I 4 adopted is a molecular sieve dryer, and the molecular sieve of the molecular sieve dryer is 4A° molecular sieve, 5A° molecular sieve or dehydrated molecular sieve; the drying tower II 15 is set as a silica gel drying tower, and the desiccant in the silica gel drying tower is silica gel, and the silica gel is coarse mesh silica gel or microporous silica gel, and the mesh number of the silica gel is 50 - 150 mesh or microporous silica gel. In this embodiment, the feed pipe I 24 inserted into the liquid inlet I 6 extends into the fluorination reactor 5, the feed pipe II 25 inserted into the gas inlet II 7 extends into the fluorination reactor 5, and the feed pipe III 26 inserted into the inlet III 23 extends to the bottom of the fluorination reactor 5 and is connected to the gas distributor 8. In this embodiment, the separation tower 11 is set as a packed tower, and several packings 12 are placed from top to bottom in the packed tower, and the packings 12 are stainless steel Pall rings or Intalox saddles. In this embodiment, the high-efficiency dryer III 20 is set as a molecular dryer, and the desiccant of the molecular dryer adopts molecular sieve, and the mesh number of the molecular sieve is 10 - 30 mesh, and the molecular sieve is 4A° molecular sieve, 5A° molecular sieve or special molecular sieve for refrigerant dehydration.

[0019] The preparation process of highly pure difluoroethane is further described by the following examples: Example 1. The present invention also discloses a preparation method for reacting high-purity difluoroethane, which comprises the following steps: Step 1, first pre-treat the raw material acetylene. Feed the raw material acetylene into the acetylene water-ring pump 1, and then discharge it successively into the acetylene refrigeration dehydrator 2 and the acetylene deep refrigeration dehydrator 3 through the outlet of the acetylene water-ring pump 1 for dehydration. After the dehydration is completed, it enters the dryer I 4 for drying treatment to obtain acetylene gas with qualified water content. The water content of the qualified acetylene gas is controlled at 5 ppm. Step 2, feed the hydrogen fluoride liquid into the liquid inlet I 6 at the upper part of the fluorination reactor 5, and feed the dehydrated acetylene gas into the fluorination reactor 5 through the gas inlet II 7 at the upper part of the fluorination reactor 5, and then transport it to the gas distributor 8 at the bottom of the fluorination reactor 5. Utilize the bubbling effect of the acetylene gas in the gas distributor 8 to achieve sufficient contact and reaction. Then add the catalyst fluorosulfonic acid into the fluorination reactor 5 through the inlet III 23 at the upper part of the fluorination reactor 5. After the acetylene gas, hydrogen fluoride liquid and catalyst are fully mixed and reacted in the fluorination reactor 5, a gas-phase mixture is obtained. The gas-phase mixture passes successively through the discharge port 9 on the side of the fluorination reactor 5, the pipeline I 10 and the feed port 22 on the side of the separation column 11 and then enters the separation column 11 for separation. The gas-phase mixture includes low-boiling vinyl fluoride and crude difluoroethane. The low-boiling vinyl fluoride and crude difluoroethane enter the separation column 11 filled with packing together, and the condenser uses -15 °C chilled brine for separation. Then, through the pipeline II 12 connected to the bottom of the separation column 11, the separated vinyl fluoride liquid is refluxed to the fluorination reactor 5, so that the separated vinyl fluoride continues to react in the fluorination reactor 5. The crude difluoroethane is discharged from the top of the separation column 11. The content of the crude difluoroethane after separation by the separation column 11 can reach 95%. Step 3, feed the crude product after separation by the separation column 11 into the water washing tower 13, the alkali washing tower 14 and the dryer II 15 through the first condensation by the separation column condenser 12 to remove the impurities in the crude product. Step 4, then compress the crude product after removing the impurities through the centrifugal gas compressor 16 and condense it through the gas condenser 17, and then send it to the degassing tower 18 to remove the remaining impurities, and finally send it to the rectification tower 19 for rectification to produce the difluoroethane finished product. The difluoroethane finished product is dried and dehydrated through the high-efficiency dryer III 20 to obtain high-purity difluoroethane, and the high-purity difluoroethane is sent to the finished product storage tank 21.In this embodiment, the freezing liquid of the acetylene freezing dehydrator 2 is 5°C freezing brine, and the freezing liquid of the acetylene cryogenic dehydrator 3 is -15°C freezing brine for acetylene. In step two of this embodiment, the feed pipe I 24 for acetylene gas, the feed pipe II 25 for hydrogen fluoride liquid, and the feed pipe III 26 for fluorosulfonic acid are respectively inserted into the inside of the fluorination reactor 5 for feeding. Among them, the acetylene gas forms acetylene gas bubbles through the gas distributor 8. The fluorination reactor 5 and the separation tower are fed or discharged through the gas phase pipeline 10 and the liquid phase pipeline 12, becoming a new reaction type integrating reaction and distillation. The separation tower 11 is a packed tower, and 5 sections of packing are distributed in sequence from top to bottom in the separation tower 11, so that the mixture in the fluorination reactor can be fully contacted to separate difluoroethane. In step two, the temperature of the full mixing reaction in the fluorination reactor 5 is controlled at 30°C, and the reaction pressure is controlled at 0.2 MPa. In step two, the molar flow ratio of acetylene to hydrogen fluoride is 1:2.1. In step three of this embodiment, the top temperature of the separation tower 11 is controlled at 1°C. In step four of this embodiment, the impurities removed by the degassing tower include acetylene, vinyl fluoride, and nitrogen. The pressure of the degassing tower is controlled at 0.95 MPa, and the top temperature is controlled at 35°C. The light removal amount is controlled at 0.1 kg / h. The pressure of the rectification tower 19 is controlled at 0.55 MPa, the top temperature of the rectification tower 19 is controlled at 30°C, and the reflux ratio is controlled between 3. After rectification by the rectification tower, the purity reaches 99.95%. The desiccant in the high-efficiency dryer III 20 is molecular sieve or calcium chloride, where the molecular sieve is 4A° molecular sieve, 5A° molecular sieve, or a special molecular sieve for refrigerant dehydration; the mesh number is 10 mesh. Finally, the purity of the high-purity difluoroethane obtained after high-efficiency drying reaches 99.99%.

[0020] Example 2, Example 1, The present invention also discloses a preparation method for reacting high-purity difluoroethane, which comprises the following steps: Step 1, first pre-treat the raw material acetylene. Feed the raw material acetylene into the acetylene water ring pump 1, and then discharge it successively into the acetylene freezing dehydrator 2 and the acetylene deep cooling dehydrator 3 through the outlet of the acetylene water ring pump 1 for dehydration. After the dehydration is completed, enter the dryer I 4 for drying treatment to obtain acetylene gas with qualified water content. The water content of the qualified acetylene gas is controlled at 8 ppm. Step 2, feed the hydrogen fluoride liquid into the liquid inlet I 6 at the upper part of the fluorination reactor 5, and feed the dehydrated acetylene gas into the fluorination reactor 5 through the gas inlet II 7 at the upper part of the fluorination reactor 5, and then transport it to the gas distributor 8 at the bottom of the fluorination reactor 5. Utilize the bubbling effect of the acetylene gas in the gas distributor 8 to achieve sufficient contact and reaction. Then add the catalyst fluorosulfonic acid into the fluorination reactor 5 through the inlet III 23 at the upper part of the fluorination reactor 5. After the acetylene gas, hydrogen fluoride liquid and catalyst are fully mixed and reacted in the fluorination reactor 5, a gas-phase mixture is obtained. The gas-phase mixture passes through the discharge port 9 on the side of the fluorination reactor 5, the pipeline I 10 and the feed port 22 on the side of the separation tower 11 in sequence and then enters the separation tower 11 for separation. The gas-phase mixture includes low-boiling vinyl fluoride and crude difluoroethane. The low-boiling vinyl fluoride and crude difluoroethane enter the separation tower 11 filled with packing together, and the condenser uses -15°C chilled brine for separation. Then, through the pipeline II 12 connected to the bottom of the separation tower 11, the separated vinyl fluoride liquid is refluxed to the fluorination reactor 5, so that the separated vinyl fluoride continues to react in the fluorination reactor 5. The crude difluoroethane is discharged from the top of the separation tower 11. The content of the crude difluoroethane after separation by the separation tower 11 can reach 96%. Step 3, condense the crude product separated by the separation tower 11 for the first time through the separation tower condenser 12 and then enter the water washing tower 13, the alkali washing tower 14 and the dryer II 15 to remove the impurities in the crude product. Step 4, then compress the crude product after removing the impurities through the centrifugal gas compressor 16 and condense it through the gas condenser 17, and then send it to the degassing tower 18 to remove the remaining impurities, and finally send it to the rectification tower 19 for rectification to produce the difluoroethane finished product. The difluoroethane finished product is dried and dehydrated through the high-efficiency dryer III 20 to obtain high-purity difluoroethane, and the high-purity difluoroethane is sent to the finished product storage tank 21.In this embodiment, the refrigerating liquid of the acetylene freezing dehydrator 2 is 5°C freezing brine, and the refrigerating liquid of the acetylene cryogenic dehydrator 3 is -15°C freezing brine for acetylene. In step two of this embodiment, the feed pipe I 24 for acetylene gas, the feed pipe II 25 for hydrogen fluoride liquid, and the feed pipe III 26 for fluorosulfonic acid are respectively inserted into the inside of the fluorination reactor 5 for feeding. Among them, the acetylene gas is bubbled through the gas distributor 8. The fluorination reactor 5 and the separation column are fed or discharged through the gas phase pipeline 10 and the liquid phase pipeline 12, becoming a new reaction type that combines reaction and distillation. The separation column 11 is a packed column, and 5 sections of packing are distributed in sequence from top to bottom in the separation column 11, so that the mixture in the fluorination reactor can be fully contacted to separate difluoroethane. In step two, the temperature of the full mixing reaction in the fluorination reactor 5 is controlled at 40°C, and the reaction pressure is controlled at 0.25 MPa. In step two, the molar flow ratio of acetylene to hydrogen fluoride is 1:2.5. In step three of this embodiment, the top temperature of the separation column 11 is controlled at 3°C. In step four of this embodiment, the impurities removed by the degassing tower include acetylene, vinyl fluoride, and nitrogen. The pressure of the degassing tower is controlled at 0.95 MPa, and the top temperature is controlled at 40°C. The light component removal amount is controlled at 0.2 kg / h. The pressure of the rectification column 19 is controlled at 0.65 MPa, the top temperature of the rectification column 19 is controlled at 32°C, and the reflux ratio is controlled between 4. After rectification in the rectification column, the purity reaches 99.95%. The desiccant in the high-efficiency dryer 20 is molecular sieve or calcium chloride, where the molecular sieve is 4A° molecular sieve, 5A° molecular sieve, or special molecular sieve for refrigerant dehydration; the mesh number is 25. Finally, the purity of the high-purity difluoroethane obtained after high-efficiency drying reaches 99.99%.

[0021] Example 3, Example 1. The present invention also discloses a preparation method for reacting high-purity difluoroethane, which comprises the following steps: Step 1, first pre-treat the raw material acetylene. Feed the raw material acetylene into the acetylene water ring pump 1, and then discharge it successively into the acetylene freezing dehydrator 2 and the acetylene deep cooling dehydrator 3 through the outlet of the acetylene water ring pump 1 for dehydration. After the dehydration is completed, enter the dryer I 4 for drying treatment to obtain acetylene gas with qualified water content. The water content of the qualified acetylene gas is controlled at 5-10 ppm; Step 2, feed the hydrogen fluoride liquid into the liquid inlet I 6 at the upper part of the fluorination reactor 5, and feed the dehydrated acetylene gas into the fluorination reactor 5 through the gas inlet II 7 at the upper part of the fluorination reactor 5, and then transport it to the gas distributor 8 at the bottom of the fluorination reactor 5. Utilize the bubbling effect of the acetylene gas in the gas distributor 8 to achieve sufficient contact and reaction. Then add the catalyst fluorosulfonic acid into the fluorination reactor 5 from the inlet III 23 at the upper part of the fluorination reactor 5. After the acetylene gas, hydrogen fluoride liquid and catalyst are fully mixed and reacted in the fluorination reactor 5, a gas-phase mixture is obtained. The gas-phase mixture passes through the discharge port 9 on the side of the fluorination reactor 5, the pipeline I 10 and the feed port 22 on the side of the separation tower 11 in sequence and then enters the separation tower 11 for separation. The gas-phase mixture includes low-boiling vinyl fluoride and crude difluoroethane. The low-boiling vinyl fluoride and the crude difluoroethane enter the separation tower 11 filled with packing together, and the condenser uses -15°C chilled brine for separation. Then, the separated vinyl fluoride liquid is refluxed to the fluorination reactor 5 through the pipeline II 12 connected to the bottom of the separation tower 11, so that the separated vinyl fluoride continues to react in the fluorination reactor 5. The crude difluoroethane is discharged from the top of the separation tower 11, and the content of the crude difluoroethane after being separated by the separation tower 11 can reach 98%; Step 3, feed the crude product separated by the separation tower 11 into the water washing tower 13, the alkali washing tower 14 and the dryer II 15 after the first condensation by the separation tower condenser 12 to remove the impurities in the crude product; Step 4, then compress the crude product with the removed impurities by the centrifugal gas compressor 16 and condense it by the gas condenser 17, and then send it to the degassing tower 18 to remove the remaining impurities, and finally send it to the rectification tower 19 for rectification to produce the difluoroethane finished product. The difluoroethane finished product is dried and dehydrated by the high-efficiency dryer III 20 to obtain high-purity difluoroethane, and the high-purity difluoroethane is sent to the finished product storage tank 21.In this embodiment, the refrigerating liquid of the acetylene refrigerating dehydrator 2 is 5°C refrigerating brine, and the refrigerating liquid of the acetylene cryogenic dehydrator 3 is -15°C refrigerating brine for acetylene. In step two of this embodiment, the feed pipe I 24 for acetylene gas, the feed pipe II 25 for hydrogen fluoride liquid, and the feed pipe III 26 for fluorosulfonic acid are respectively inserted into the inside of the fluorination reactor 5 for feeding. Among them, the acetylene gas forms acetylene gas bubbles through the gas distributor 8. The fluorination reactor 5 and the separation column are fed or discharged through the gas-phase pipeline 10 and the liquid-phase pipeline 12, becoming a new reaction type that combines reaction and distillation. The separation column 11 is a packed column, and there are 5 sections of packing distributed from top to bottom in the separation column 11, which can enable the full contact of the mixture in the fluorination reactor, and difluoroethane is separated out. In step two, the temperature of the full mixing reaction in the fluorination reactor 5 is controlled at 45°C, and the reaction pressure is controlled at 0.3 MPa. In step two, the molar flow ratio of acetylene to hydrogen fluoride is 1:2.8. In step three of this embodiment, the top temperature of the separation column 11 is controlled at 5°C. In step four of this embodiment, the impurities removed by the degassing tower include acetylene, vinyl fluoride, and nitrogen. The pressure of the degassing tower is controlled at 1.05 MPa, and the top temperature is controlled at 40°C. The light removal amount is controlled at 0.3 kg / h. The pressure of the rectification column 19 is controlled at 0.8 MPa, the top temperature of the rectification column 19 is controlled at 35°C, and the reflux ratio is controlled between 5. After rectification in the rectification column, the purity reaches 99.95%. The desiccant in the high-efficiency dryer III 20 is molecular sieve or calcium chloride, where the molecular sieve is 4A° molecular sieve, 5A° molecular sieve, or a special molecular sieve for refrigerant dehydration; the mesh number is 10 - 30 mesh. Finally, the high-purity difluoroethane prepared after high-efficiency drying has a purity of 99.99%.

[0022] Without being limited thereto, any change or replacement that can be thought of without creative work shall be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope defined by the claims.

Claims

1. A preparation method for reacting high-purity difluoroethane, characterized in that it It includes the following steps: Step 1: First, pre-treat the raw material acetylene. Feed the raw material acetylene into the acetylene water ring pump (1), and then discharge it into the acetylene freezing dehydrator (2) and the acetylene deep cooling dehydrator (3) in sequence through the outlet of the acetylene water ring pump (1) for dehydration. After the dehydration is completed, enter the dryer I (4) for drying treatment to obtain acetylene gas with qualified water content. The water content of the qualified acetylene gas is controlled at 5 - 10 ppm; Step 2: Feed the hydrogen fluoride liquid into the liquid inlet I (6) at the upper part of the fluorination reactor (5), and feed the dehydrated acetylene gas into the fluorination reactor (5) through the gas inlet II (7) at the upper part of the fluorination reactor (5). Then transport it to the gas distributor (8) at the bottom of the fluorination reactor (5). Utilize the bubbling effect of the acetylene gas in the gas distributor (8) to achieve full contact and reaction. Then add the catalyst fluorosulfonic acid into the fluorination reactor (5) through the inlet III (23) at the upper part of the fluorination reactor (5). After the acetylene gas, hydrogen fluoride liquid, and catalyst are fully mixed and reacted in the fluorination reactor (5), a gas-phase mixture is obtained. The gas-phase mixture passes through the discharge port (9) on the side of the fluorination reactor (5), the pipeline I (10), and the feed port (22) on the side of the separation tower (11) in sequence and then enters the separation tower (11) for separation. The gas-phase mixture includes low-boiling vinyl fluoride and crude difluoroethane. The low-boiling vinyl fluoride and the crude difluoroethane enter the separation tower (11) filled with packing together. The condenser uses -15°C freezing brine for separation. Then, through the pipeline II (12) connected to the bottom of the separation tower (11), the separated vinyl fluoride liquid is refluxed to the fluorination reactor (5) to enable the separated vinyl fluoride to continue to react in the fluorination reactor (5). The crude difluoroethane is discharged from the top of the separation tower (11). The content of the crude difluoroethane after separation by the separation tower (11) can reach 95 - 98%; Step 3: Feed the crude product after separation by the separation tower (11) into the water washing tower (13), the alkali washing tower (14), and the dryer II (15) after the first condensation by the separation tower condenser (12) to remove impurities in the crude product; Step 4: Then, after compressing the crude product with impurities removed by the centrifugal gas compressor (16) and condensing it by the gas condenser (17), send it to the degassing tower (18) to remove the remaining impurities, and finally send it to the rectification tower (19) for rectification to produce difluoroethane finished product. The difluoroethane finished product is dried and dehydrated by the high-efficiency dryer III (20) to obtain high-purity difluoroethane, and the high-purity difluoroethane is sent to the finished product storage tank (21).

2. The preparation method of high-purity difluoroethane according to claim 1, characterized in that In Step 1, the freezing liquid of the acetylene freezing dehydrator (2) uses 5°C freezing brine, and the freezing liquid of the acetylene deep cooling dehydrator (3) uses -15°C freezing brine for acetylene.

3. The preparation method of high-purity difluoroethane according to claim 1, characterized in that In Step 2, the feed pipe I (24) for acetylene gas, the feed pipe II (25) for hydrogen fluoride liquid, and the feed pipe III (26) for fluorosulfonic acid are respectively inserted into the inside of the fluorination reactor (5) for feeding. Among them, the acetylene gas forms acetylene gas bubbles through the gas distributor (8). The fluorination reactor (5) and the separation column are fed or discharged through the gas-phase pipeline (10) and the liquid-phase pipeline (12), becoming a new reaction type that combines reaction and distillation. The separation column (11) is a packed column, and 5 sections of packing are successively distributed from top to bottom in the separation column (11), so that the mixture in the fluorination reactor can be fully contacted to separate difluoroethane. In Step 2, the temperature for the full mixing reaction in the fluorination reactor (5) is controlled at 30 - 45 °C, the reaction pressure is controlled at 0.2 - 0.3 MPa, and the molar flow ratio of acetylene to hydrogen fluoride is 1:2.1 - 2.

8.

4. The preparation method of high-purity difluoroethane according to claim 1, characterized in that In Step 3, the top temperature of the separation column (11) is controlled at -12 - 5 °C.

5. The preparation method of high-purity difluoroethane according to claim 1, characterized in that In Step 4, the impurities removed by the degassing tower include acetylene, vinyl fluoride, and nitrogen. The pressure of the degassing tower is controlled at 0.95 - 1.05 MPa, the top temperature is controlled at 35 - 40 °C, the light component removal amount is controlled at 0.1 - 0.3 kg / h, the pressure of the rectification column (19) is controlled at 0.55 - 0.8 MPa, the top temperature of the rectification column (19) is controlled at 30 - 35 °C, and the reflux ratio is controlled between 3 - 5. The purity after rectification in the rectification column reaches 99.95%. The desiccant in the high-efficiency dryer III (20) is molecular sieve or calcium chloride. Among them, the molecular sieve is 4A° molecular sieve, 5A° molecular sieve, or the special molecular sieve for refrigerant dehydration; the mesh number is 10 - 30 mesh. Finally, the purity of the high-purity difluoroethane obtained after high-efficiency drying reaches 99.99%.

6. A preparation device for reacting to produce high-purity difluoroethane, characterized in that It includes an acetylene water-ring pump (1), an acetylene freezing dehydrator (2), an acetylene cryogenic dehydrator (3), a dryer I (4), a fluorination reactor (5), a separation column (11), a water-washing column (13), an alkali-washing column (14), a drying column III (15), a centrifugal gas compressor (16), a gas condenser (17), a degassing column (18), a rectification column (19), a high-efficiency dryer III (20) and a finished product storage tank (21). The outlet of the acetylene water-ring pump (1) is sequentially connected to the gas inlet II (7) at the upper part of the fluorination reactor (5) through the acetylene freezing dehydrator (2), the acetylene cryogenic dehydrator (3) and the dryer I (4). A liquid inlet I (6) and an inlet III (23) are also provided at the upper part of the fluorination reactor (5). A gas distributor (8) is provided at the bottom inside the fluorination reactor (5). The discharge port (9) provided on the side of the fluorination reactor (5) is connected to the feed port (22) on the side of the separation column (11) through a pipeline I (10). The reflux port at the bottom of the separation column (11) is connected to the reflux port on the side of the fluorination reactor (5) through a pipeline II (12). The gas outlet at the top of the separation column (11) is connected to a separation column condenser (12). The separation column condenser (12) is sequentially connected to the side inlet of the degassing column (18) through the water-washing column (13), the alkali-washing column (14), the drying column II (15), the centrifugal gas compressor (16) and the gas condenser (17). The bottom outlet of the degassing column is connected to the feed port of the rectification column (19). The discharge port of the rectification column (19) is connected to the finished product storage tank (21) through the high-efficiency dryer III (20).

7. The high-purity difluoroethane reaction preparation device according to claim 6, characterized in that The dryer I (4) is set as a molecular sieve dryer. The molecular sieve of the molecular sieve dryer is 4A° molecular sieve, 5A° molecular sieve or dehydration molecular sieve; the drying column II (15) is set as a silica gel drying column. The desiccant in the silica gel drying column is silica gel. The silica gel is coarse mesh silica gel or microporous silica gel, and the mesh number of the silica gel is 50 - 150 mesh or microporous silica gel.

8. The high-purity difluoroethane reaction preparation device according to claim 6, characterized in that The feed pipe I (24) inserted into the liquid inlet I (6) extends into the fluorination reactor (5). The feed pipe II (25) inserted into the gas inlet II (7) extends into the fluorination reactor (5). The feed pipe III (26) inserted into the inlet III (23) extends to the bottom of the fluorination reactor (5) and is connected to the gas distributor (8).

9. The high-purity difluoroethane reaction preparation device according to claim 6, characterized in that The separation column (11) is set as a packed column. A number of packings (12) are placed from top to bottom in the packed column. The packing (12) is a stainless steel Pall ring or a saddle ring.

10. The high-purity difluoroethane reaction preparation device according to claim 6, characterized in that The high-efficiency dryer III (20) is set as a molecular dryer. The desiccant of the molecular dryer uses molecular sieve. The mesh number of the molecular sieve is 10 - 30 mesh, and the molecular sieve is 4A° molecular sieve, 5A° molecular sieve or special molecular sieve for refrigerant dehydration.

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