Continuous preparation device of hexafluoro-1, 3-butadiene intermediate

Abstract

The utility model provides a continuous preparation device of a hexafluoro-1, 3-butadiene intermediate, which comprises a raw material tank, a preheater, a fixed bed reactor, a primary condenser, a crude product storage tank, secondary condensing equipment, a primary freezing separator, a heavy component recovery tank, a secondary freezing separator, a product storage tank and a light component recovery tank, the raw material tank, the preheater, the fixed bed reactor, the crude product storage tank, the first-stage freezing separator and the second-stage freezing separator are sequentially arranged through pipelines, the first-stage condenser is arranged at the top of the crude product storage tank, the second-stage condensing equipment is connected with the top of the first-stage condenser, and the bottom of the second-stage condensing equipment flows back to the raw material tank and the light component recovery tank; the heavy component recovery tank is connected with the bottom of the first-stage freezing separator, and the product storage tank is connected with the bottom of the second-stage freezing separator; and the bottom of the secondary freezing separator is connected with the light component recovery tank and the raw material tank. The device is simple in process, mild in condition, low in energy consumption, simple in product separation, high in separation speed, good in selectivity and convenient for subsequent purification.

Description

Technical Field

[0001] The utility model belongs to the technical field of hexafluoro-1,3-butadiene preparation, in particular to a continuous preparation device for a hexafluoro-1,3-butadiene intermediate. Background Art

[0002] Hexafluoro-1,3-butadiene, also known as hexafluorobutadiene, perfluorobutadiene, English name Hexafluoro-1,3-butadiene, abbreviated as HFBD, has a molecular formula of C4F6, a relative molecular mass of 162, a melting point of -132°C, and a boiling point of 4-6°C. Under standard conditions, it is a colorless, odorless, toxic, flammable and compressible gas that is insoluble in water. Its ozone depletion potential (ODP) is 0, its global warming potential (GWP) is 290, and its average lifetime in the atmosphere is 1.9 days. It is a green and environmentally friendly perfluorinated olefin.

[0003] Hexafluoro-1,3-butadiene is a widely used industrial raw material. Its downstream products can be used in precision electronic circuit board cleaning agents and pesticides. It also has high application value in the synthesis of fluorinated fine chemicals such as fluorinated pharmaceutical intermediates. In the synthesis of fluorinated polymers, it can be used as a polymer monomer to prepare polyhexafluorobutadiene, and can also be combined with other monomers to synthesize fluorinated rubber and fluorinated elastomers.

[0004] CN201410856791.8 discloses a method for preparing 1,2-dichlorohexafluoro-3-butene: preheating chlorotrifluoroethylene to 160-250°C; then cracking the preheated material at 350-500°C to produce 1,2-dichlorohexafluoro-3-butene and dichlorohexafluorocyclobutane as a pyrolysis product; the separated dichlorohexafluorocyclobutane is recycled to the chlorotrifluoroethylene preheating step. This high reaction temperature can cause carbonization of the material, reducing the service life of the equipment.

[0005] CN202110224766.8 directly dechlorinates 1,2-dichlorohexafluoro-3-butene in the presence of zinc, an organic solvent, and an initiator to synthesize hexafluoro-1,3-butadiene. After the reaction, distillation removes the heavy components to produce hexafluoro-1,3-butadiene with a purity exceeding 99%. The heavy components are then mixed with the raw material 1,2-dichlorohexafluoro-3-butene and reused. The hexafluoro-1,3-butadiene byproducts are rearranged to hexafluoro-1,3-butadiene using an iridium clamp catalyst, CsF, or KF. Further distillation removes the light components and filtration yields the product hexafluoro-1,3-butadiene. The light components from the distillation are catalytically converted and reused. The raw materials for this patent are difficult to source and require an expensive iridium clamp catalyst. The patent focuses on the distillation and catalytic conversion of the impurities 1,2-dichlorohexafluorocyclobutane and hexafluoro-2,3-dichloro-2-butene in the raw materials.

[0006] CN202210174985.4 discloses a production process and apparatus for thermally polymerizing chlorotrifluoroethylene to form 1,2-dichlorohexafluoro-3-butene, followed by dechlorination to synthesize hexafluoro-1,3-butadiene. This invention primarily addresses a production apparatus for the thermal polymerization process. The process requires separating 1,2-dichlorohexafluoro-3-butene from the thermal polymerization product, followed by a liquid-phase dechlorination reaction in a zinc / ethanol solvent for 24 hours, which precludes continuous production. The invention presents difficulties in separating 1,2-dichlorohexafluoro-3-butene, and the actual production efficiency of the product from this process is unclear.

[0007] In summary, developing a method for preparing hexafluoro-1,3-butadiene with cheap raw materials, convenient sources, simple operation, mild conditions, low energy consumption, low cost, simple product separation, good selectivity, and scalable continuous production is an urgent problem to be solved by those skilled in the art. Utility Model Content

[0008] In view of this, the utility model aims to propose a continuous preparation device for hexafluoro-1,3-butadiene intermediate, so as to provide a device with simple process, easy operation, mild conditions, low energy consumption, simple product separation, faster separation speed than distillation, good selectivity, convenient subsequent purification, and capable of realizing scaled-up continuous production.

[0009] In order to achieve the above-mentioned purpose, the technical solution of the utility model is achieved as follows:

[0010] A continuous preparation device for hexafluoro-1,3-butadiene intermediate, comprising a raw material tank, a preheater, a fixed bed reactor, a primary condenser, a crude product storage tank, a secondary condensing device, a primary refrigeration separator, a heavy component recovery tank, a secondary refrigeration separator, a product storage tank, and a light component recovery tank;

[0011] The raw material tank, preheater, fixed bed reactor, crude product storage tank, primary refrigeration separator, and secondary refrigeration separator are arranged in sequence through pipelines. The primary condenser is arranged on the top of the crude product storage tank, the secondary condensing device is connected to the top outlet of the primary condenser, and the bottom outlet of the secondary condensing device is refluxed to the raw material tank and the light component recovery tank;

[0012] The heavy component recovery tank is connected to the bottom outlet of the first-stage freezing separator, and the product storage tank is connected to the bottom outlet of the second-stage freezing separator;

[0013] The bottom outlet of the secondary freezing separator is connected to the light component recovery tank and the raw material tank.

[0014] Furthermore, the outlet of the raw material tank is connected to the gas phase inlet of the preheater, the gas phase outlet of the preheater is connected to the gas phase inlet of the fixed bed reactor, the outlet of the fixed bed reactor is connected to the inlet of the crude product storage tank, the bottom liquid phase outlet of the crude product storage tank is connected to the top inlet of the first-stage freezing separator, the bottom outlet of the first-stage freezing separator is connected to the top inlet of the second-stage freezing separator and the heavy component recovery tank, and the bottom outlet of the second-stage freezing separator is connected to the light component recovery tank and the product storage tank.

[0015] Furthermore, the secondary condensing equipment includes a secondary condenser, a raw material recovery storage tank, a spare secondary condenser, and a spare raw material recovery storage tank, the top of the raw material recovery storage tank is connected to the secondary condenser, and the top of the spare raw material recovery storage tank is connected to the spare secondary condenser;

[0016] The top of the crude product storage tank is connected to a primary condenser, the top outlet of the primary condenser is connected to the top inlet of the raw material recovery storage tank, and the top outlet of the secondary condenser is connected to the top inlet of the standby raw material recovery storage tank;

[0017] The top outlet of the secondary condenser and the top outlet of the standby secondary condenser are connected to the tail gas treatment device;

[0018] The bottom outlet of the raw material recovery storage tank and the bottom outlet of the standby raw material recovery storage tank are connected to the light component recovery tank and the raw material tank.

[0019] The top of the crude product storage tank is connected to a primary condenser. After the reacted gas is condensed by the primary condenser, the generated intermediate crude product will be stored in the crude product storage tank, and a small amount of light components and most of the unreacted raw materials will be discharged from the top outlet of the primary condenser in a gaseous state;

[0020] The top of the raw material recovery tank is connected to a secondary condenser. After the reacted gas is condensed by the secondary condenser, the remaining small amount of light components and most of the unreacted raw materials will be stored in the raw material recovery tank, and a small amount of raw materials and part of the non-condensable gas will be discharged from the top outlet of the secondary condenser and passed into the tail gas treatment device; the spare raw material recovery tank and the spare secondary condenser are connected in parallel with the raw material recovery tank and the secondary condenser, and have the same functions as the raw material recovery tank and the secondary condenser. The secondary condensation equipment is set as two sets of equipment, one for standby and one for use, to achieve continuous production.

[0021] Furthermore, the top inlets of the primary condenser, the raw material recovery storage tank, the spare raw material recovery storage tank, the primary freezing separator, and the secondary freezing separator are all provided with nitrogen pressurizing pipes.

[0022] Furthermore, the crude product storage tank, raw material recovery storage tank, and spare raw material recovery storage tank are all provided with liquid level gauges and vents.

[0023] When the liquid level in the raw material recovery tank and the spare raw material recovery tank exceeds 2 / 3 of the scale, the recovered raw materials in the raw material recovery tank and the spare raw material recovery tank are pressed into the light component recovery tank by nitrogen pressurization; when the liquid level in the crude product tank exceeds 2 / 3 of the scale, the crude product in the crude product tank is pressed into the primary refrigeration separator by nitrogen pressurization.

[0024] The crude product flows into the primary freezing separator, and after being frozen by the refrigerant, the heavy component will precipitate and crystallize. After being pressurized by nitrogen, the filtrate flows into the secondary freezing separator. Then, the refrigerant temperature is increased, and the remaining filter cake will be re-liquefied and pressed into the heavy component recovery tank by nitrogen pressurization.

[0025] The filtrate in the first-stage freezing separator is the intermediate between the unprecipitated light component and hexafluoro-1,3-butadiene. After flowing into the second-stage freezing separator, the hexafluoro-1,3-butadiene intermediate will precipitate and crystallize after being frozen by the refrigerant. After being pressurized by nitrogen, the filtrate flows into the light component recovery tank. Then, the refrigerant temperature is increased, and the remaining filter cake will be re-liquefied and pressed into the product storage tank by nitrogen pressurization.

[0026] The filtrate in the first-stage freezing separator is an intermediate of unprecipitated light components and hexafluoro-1,3-butadiene, and the filter cake is a heavy component that has precipitated crystals; the filtrate in the second-stage freezing separator is an intermediate of hexafluoro-1,3-butadiene.

[0027] Furthermore, a flow controller is provided on the connecting pipeline between the raw material tank and the preheater.

[0028] Furthermore, the first-stage freeze separator and the second-stage freeze separator include a first shell, a second shell, a stirring assembly, a discharge pipe, a valve, and a filter. The first shell and the second shell are funnel-shaped structures. The first shell is mounted on the outside of the second shell, and an enclosed space is formed between the first shell and the second shell. The stirring assembly is arranged inside the second shell, the discharge pipe is arranged below the second shell, and the valve and the filter are arranged on the discharge pipe in sequence from top to bottom.

[0029] Furthermore, the stirring assembly includes a motor, a stirring shaft, and a stirring paddle. The mounting end of the motor is arranged above the first shell, the output shaft of the motor is connected to one end of the stirring shaft, the other end of the stirring shaft passes through the top of the first shell and the second shell and extends to the inside of the second shell. The stirring paddle is arranged on the stirring shaft, and the stirring paddle is arranged inside the second shell.

[0030] A filter cloth is arranged in the filter.

[0031] Furthermore, a liquid inlet pipe is provided on the lower side of the first shell, and a liquid outlet pipe is provided on the other upper side of the first shell. One end of the liquid inlet pipe and the liquid outlet pipe is connected to the freezer, and the other end of the liquid inlet pipe and the liquid outlet pipe is arranged between the first shell and the second shell.

[0032] Furthermore, the top of the second shell is provided with a feed pipe, a nitrogen pressure pipe, a first sight glass and a second sight glass distributed along the circumference; the first sight glass is used for adding light, and the second sight glass is an observation hole.

[0033] A vertically arranged liquid level gauge is provided on the outside of the second shell. The top of the liquid level gauge is connected to the top of the second shell through a first liquid level tube, and the bottom of the liquid level gauge is connected to the discharge pipe through a second liquid level tube, and the second liquid level tube is arranged above the valve.

[0034] The first shell and the second shell of the primary refrigeration separator and the secondary refrigeration separator form a jacket structure, and a refrigerator is connected between the first shell and the second shell. The temperature of the primary refrigeration separator and the secondary refrigeration separator can be adjusted by the refrigerator, and the condensate is introduced from the liquid inlet pipe and discharged from the liquid outlet pipe to realize the circulation of the condensate.

[0035] Preferably, the condensate is a mixed liquid of ethanol and water.

[0036] The freezer adopts the existing technology.

[0037] The temperature of the first-stage freezing separator is -30 to -20°C, and the temperature of the second-stage freezing separator is -60 to -50°C.

[0038] Compared with the prior art, the continuous preparation device of hexafluoro-1,3-butadiene intermediate described in the present invention has the following advantages:

[0039] (1) The utility model adopts a freezing separation method according to different freezing points. The temperature of the first-stage freezing separator is -30 to -20°C, and the temperature of the second-stage freezing separator is -60 to -50°C. This can significantly improve the production process, increase production efficiency, reduce the amount of three wastes, and effectively reduce production costs;

[0040] (2) The utility model adopts a freezing separation method, which is more suitable for industrialization. After industrialization, liquid nitrogen can be used to replace the compressor to configure low-temperature circulating fluids of different temperatures, thereby effectively reducing production costs;

[0041] (3) The purity of the hexafluoro-1,3-butadiene intermediate collected by the freezing separation method of the present invention can reach more than 90%, and the separation time is shorter than that of the distillation purification method, which can significantly improve the production efficiency;

[0042] (4) The fixed bed reactor of the present invention is connected in series with the primary condenser and the secondary condensing equipment, and the secondary condenser and the spare secondary condenser are connected in parallel, so that continuous production can be achieved;

[0043] (5) The continuous preparation device of the hexafluoro-1,3-butadiene intermediate described in the utility model has the advantages of simple process, easy operation, low energy consumption, mild operating conditions, simple product separation, faster separation speed than distillation, good selectivity, can be directly used for subsequent production operations, effectively saves production time, and can achieve the advantages of scaled-up continuous production. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0045] Figure 1 This is a schematic diagram of a continuous preparation device for a hexafluoro-1,3-butadiene intermediate according to an embodiment of the present utility model;

[0046] Figure 2 This is a schematic flow diagram of a continuous preparation device for a hexafluoro-1,3-butadiene intermediate according to an embodiment of the present utility model;

[0047] Figure 3 This is a schematic diagram of a primary refrigeration separator and a secondary refrigeration separator according to an embodiment of the present utility model;

[0048] Figure 4 It is a side view schematic diagram of the primary refrigeration separator and the secondary refrigeration separator described in an embodiment of the present utility model.

[0049] Description of reference numerals:

[0050] 1. Raw material tank; 2. Preheater; 3. Fixed-bed reactor; 4. Primary condenser; 5. Crude product storage tank; 6. Secondary condenser; 7. Raw material recovery tank; 8. Spare secondary condenser; 9. Spare raw material recovery tank; 10. Light component recovery tank; 11. Primary refrigeration separator; 12. Heavy component recovery tank; 13. Secondary refrigeration separator; 14. Product storage tank; 15. First shell; 16. Secondary shell; 17. Discharge pipe; 18. Valve; 19. Filter; 20. Motor; 21. Stirring shaft; 22. Stirring paddle; 23. Filter cloth; 24. Liquid inlet pipe; 25. Liquid outlet pipe; 26. Feed pipe; 27. Nitrogen pressurizing pipe; 28. First sight glass; 29. ​​Second sight glass; 30. Liquid level gauge; 31. First liquid level pipe; 32. Second liquid level pipe. DETAILED DESCRIPTION

[0051] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0052] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0053] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0054] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0055] like Figures 1 to 4 As shown, a continuous preparation device for hexafluoro-1,3-butadiene intermediate includes a raw material tank 1, a preheater 2, a fixed bed reactor 3, a primary condenser 4, a crude product storage tank 5, a secondary condensing device, a primary refrigeration separator 11, a heavy component recovery tank 12, a secondary refrigeration separator 13, a product storage tank 14 and a light component recovery tank 10;

[0056] The raw material tank 1, preheater 2, fixed bed reactor 3, crude product storage tank 5, primary refrigeration separator 11, and secondary refrigeration separator 13 are arranged in sequence through pipelines, the primary condenser 4 is arranged on the top of the crude product storage tank 5, the secondary condensing device is connected to the top outlet of the primary condenser 4, and the bottom outlet of the secondary condensing device is refluxed to the raw material tank 1 and the light component recovery tank 10;

[0057] The heavy component recovery tank 12 is connected to the bottom outlet of the first-stage freezing separator 11, and the product storage tank 14 is connected to the bottom outlet of the second-stage freezing separator 13;

[0058] The bottom outlet of the secondary freezing separator 13 is connected to the light component recovery tank 10 and the raw material tank 1.

[0059] The outlet of the raw material tank 1 is connected to the gas phase inlet of the preheater 2, the gas phase outlet of the preheater 2 is connected to the gas phase inlet of the fixed bed reactor 3, the outlet of the fixed bed reactor 3 is connected to the inlet of the crude product storage tank 5, the bottom liquid phase outlet of the crude product storage tank 5 is connected to the top inlet of the first-stage refrigeration separator 11, the bottom outlet of the first-stage refrigeration separator 11 is connected to the top inlet of the second-stage refrigeration separator 13 and the heavy component recovery tank 12, and the bottom outlet of the second-stage refrigeration separator 13 is connected to the light component recovery tank 10 and the product storage tank 14.

[0060] The secondary condensing equipment includes a secondary condenser 6, a raw material recovery storage tank 7, a spare secondary condenser 8, and a spare raw material recovery storage tank 9. The top of the raw material recovery storage tank 7 is connected to the secondary condenser 6, and the top of the spare raw material recovery storage tank 9 is connected to the spare secondary condenser 8;

[0061] The top of the crude product storage tank 5 is connected to the primary condenser 4, the top outlet of the primary condenser 4 is connected to the top inlet of the raw material recovery storage tank 7, and the top outlet of the secondary condenser 6 is connected to the top inlet of the spare raw material recovery storage tank 9;

[0062] The top outlet of the secondary condenser 6 and the top outlet of the standby secondary condenser 8 are connected to the tail gas treatment device;

[0063] The bottom outlet of the raw material recovery storage tank 7 and the bottom outlet of the standby raw material recovery storage tank 9 are connected to the light component recovery tank 10 and the raw material tank 1.

[0064] The top of the crude product storage tank 5 is connected to the primary condenser 4. After the reacted gas is condensed by the primary condenser 4, the generated intermediate crude product will be stored in the crude product storage tank 5, and a small amount of light components and most of the unreacted raw materials will be discharged from the top outlet of the primary condenser 4 in a gaseous state;

[0065] The top of the raw material recovery tank 7 is connected to the secondary condenser 6. After the reacted gas is condensed by the secondary condenser 6, the remaining small amount of light components and most of the unreacted raw materials will be stored in the raw material recovery tank 7, and a small amount of raw materials and part of the non-condensable gas will be discharged from the top outlet of the secondary condenser 6 and passed into the tail gas treatment device; the spare raw material recovery tank 9 and the spare secondary condenser 8 are connected in parallel with the raw material recovery tank 7 and the secondary condenser 6, and have the same functions as the raw material recovery tank 7 and the secondary condenser 6. The secondary condensation equipment is set as two sets of equipment, one for standby and one for use, to achieve continuous production.

[0066] The top inlets of the primary condenser 4 , the raw material recovery storage tank 7 , the standby raw material recovery storage tank 9 , the primary freezing separator 11 , and the secondary freezing separator 13 are all provided with nitrogen pressurizing pipes 27 .

[0067] The crude product storage tank 5, the raw material recovery storage tank 7, and the spare raw material recovery storage tank 9 are all provided with liquid level gauges and vents.

[0068] When the liquid level in the raw material recovery tank 7 and the spare raw material recovery tank 9 exceeds 2 / 3 of the scale, the recovered raw materials in the raw material recovery tank 7 and the spare raw material recovery tank 9 are pressed into the light component recovery tank 10 by nitrogen pressurization; when the liquid level in the crude product tank 5 exceeds 2 / 3 of the scale, the crude product in the crude product tank 5 is pressed into the primary refrigeration separator 11 by nitrogen pressurization.

[0069] The crude product flows into the primary freezing separator 11. After being frozen by the refrigerant, the heavy component will precipitate and crystallize. After being pressurized by nitrogen, the filtrate flows into the secondary freezing separator 13. Then, the refrigerant temperature is increased, and the remaining filter cake will be re-liquefied and pressed into the heavy component recovery tank 12 by nitrogen pressurization.

[0070] The filtrate in the first-stage freezing separator 11 is an intermediate between the unprecipitated light component and hexafluoro-1,3-butadiene. After flowing into the second-stage freezing separator 13, the hexafluoro-1,3-butadiene intermediate will precipitate and crystallize after being frozen by the refrigerant. After being pressurized by nitrogen, the filtrate flows into the light component recovery tank 10. Then, the refrigerant temperature is increased, and the remaining filter cake will be re-liquefied and pressed into the product storage tank 14 by nitrogen pressurization.

[0071] The filtrate in the first-stage freezing separator 11 is an intermediate between the unprecipitated light component and hexafluoro-1,3-butadiene, and the filter cake is the heavy component that has precipitated crystals; the filtrate in the second-stage freezing separator 13 is an intermediate between the unprecipitated light component and hexafluoro-1,3-butadiene.

[0072] A flow controller is provided on the connecting pipeline between the raw material tank 1 and the preheater 2 .

[0073] The first-stage freezing separator 11 and the second-stage freezing separator 13 include a first shell 15, a second shell 16, a stirring assembly, a discharge pipe 17, a valve 18, and a filter 19. The first shell 15 and the second shell 16 are funnel-shaped structures. The first shell 15 is mounted on the outside of the second shell 16, and a closed space is formed between the first shell 15 and the second shell 16. The stirring assembly is arranged inside the second shell 16, the discharge pipe 17 is arranged below the second shell 16, and the valve 18 and the filter 19 are arranged on the discharge pipe 17 from top to bottom.

[0074] The stirring assembly includes a motor 20, a stirring shaft 21, and a stirring paddle 22. The mounting end of the motor 20 is arranged above the first housing 15. The output shaft of the motor 20 is connected to one end of the stirring shaft 21. The other end of the stirring shaft 21 passes through the top of the first housing 15 and the second housing 16 and extends into the interior of the second housing 16. The stirring paddle 22 is arranged on the stirring shaft 21 and is arranged inside the second housing 16.

[0075] A filter cloth 23 is provided in the filter 19 .

[0076] A liquid inlet pipe 24 is provided on one side below the first shell 15, and a liquid outlet pipe 25 is provided on the other side above the first shell 15. One end of the liquid inlet pipe 24 and the liquid outlet pipe 25 are connected to the freezer, and the other end of the liquid inlet pipe 24 and the liquid outlet pipe 25 are arranged between the first shell 15 and the second shell 16.

[0077] The top of the second shell 16 is provided with a feed pipe 26, a nitrogen pressure pipe 27, a first sight glass 28 and a second sight glass 29 distributed along the circumference; the first sight glass 28 is used for adding light, and the second sight glass 29 is an observation hole.

[0078] A vertically arranged liquid level gauge 30 is provided on the outside of the second shell 16. The top of the liquid level gauge 30 is connected to the top of the second shell 16 through a first liquid level tube 31, and the bottom of the liquid level gauge 30 is connected to the discharge pipe 17 through a second liquid level tube 32, and the second liquid level tube 32 is arranged above the valve 18.

[0079] The first shell 15 and the second shell 16 of the first-stage refrigeration separator 11 and the second-stage refrigeration separator 13 form a jacket structure, and a refrigerator is connected between the first shell 15 and the second shell 16. The temperature of the first-stage refrigeration separator 11 and the second-stage refrigeration separator 13 can be adjusted by the refrigerator, and the condensate is introduced from the liquid inlet pipe 24 and discharged from the liquid outlet pipe 25 to realize the circulation of the condensate.

[0080] Preferably, the condensate is a mixed liquid of ethanol and water.

[0081] The freezer adopts the existing technology.

[0082] The temperature of the first-stage freezing separator 11 is -30 to -20°C, and the temperature of the second-stage freezing separator 13 is -60 to -50°C.

[0083] In a specific implementation, the raw material is a liquid containing more than 99% chlorotrifluoroethylene. The flow rate is controlled by a flow controller and then the liquid is passed into a preheater 2 and then into a fixed bed reactor 3. A thermal polymerization reaction is carried out at a high temperature. The reaction product enters a primary condenser 4. Most of the product and heavy components are condensed and stored in a crude product storage tank 5. Light components such as chlorotrifluoroethylene enter a secondary condensing device for raw material recovery. The crude raw material in the crude product storage tank 5 is passed into a primary freezing separator 11 at a temperature of -30 to -20°C to separate the heavy components. The unfrozen filtrate is then passed into a secondary freezing separator 13 at a temperature of -60 to -50°C to remove the unfrozen light components to obtain a hexafluoro-1,3-butadiene intermediate containing more than 90%.

[0084] If the temperature of the primary freezing separator 11 is set to -15 to -10°C, it can be seen from the second viewing mirror 29 that no freezing crystallization occurs in the primary freezing separator 11.

[0085] If the temperature of the primary cryogenic separator 11 is set to -50 to -40°C, the filtrate is significantly reduced, and the sample test results show that most of the product is present in the heavy fraction. After separation in the secondary cryogenic separator 13 at a temperature of -60 to -50°C, a hexafluoro-1,3-butadiene intermediate with a content of 91.35% can be obtained, but the yield is relatively low.

[0086] If the temperature of the secondary freezing separator 13 is set to -80 to -70°C, after filtering through the primary freezing separator 11 at a temperature of -30 to -20°C, the filtrate is separated again through the secondary freezing separator 13 at a temperature of -80 to -70°C, and a hexafluoro-1,3-butadiene intermediate with a content of 84.75% is obtained, and the weight of the product increases slightly, wherein the main impurities are mainly light components.

[0087] If the temperature of the secondary freezing separator 13 is set to -50 to -40°C, after filtering through the primary freezing separator 11 at a temperature of -30 to -20°C, the filtrate is separated again through the secondary freezing separator 13 at a temperature of -50 to -40°C, and a hexafluoro-1,3-butadiene intermediate with a content of 96.87% is obtained. However, the product yield is low, and the recovered light components contain a large amount of hexafluoro-1,3-butadiene intermediate.

[0088] Therefore, slight adjustments to various parameters and processes will have a huge impact on the yield and purity of the product.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A continuous preparation device for a hexafluoro-1,3-butadiene intermediate, characterized in that: It includes a raw material tank (1), a preheater (2), a fixed bed reactor (3), a primary condenser (4), a crude product storage tank (5), a secondary condensing device, a primary freezing separator (11), a heavy component recovery tank (12), a secondary freezing separator (13), a product storage tank (14) and a light component recovery tank (10); The raw material tank (1), preheater (2), fixed bed reactor (3), crude product storage tank (5), primary refrigeration separator (11), and secondary refrigeration separator (13) are sequentially arranged through pipelines, the primary condenser (4) is arranged on the top of the crude product storage tank (5), the secondary condensing device is connected to the top outlet of the primary condenser (4), and the bottom outlet of the secondary condensing device is refluxed to the raw material tank (1) and the light component recovery tank (10); The heavy component recovery tank (12) is connected to the bottom outlet of the first-stage freezing separator (11), and the product storage tank (14) is connected to the bottom outlet of the second-stage freezing separator (13); The bottom outlet of the secondary freezing separator (13) is connected to the light component recovery tank (10) and the raw material tank (1).

2. The continuous preparation device of a hexafluoro-1,3-butadiene intermediate according to claim 1, characterized in that: The outlet of the raw material tank (1) is communicated with the gas phase inlet of the preheater (2), the gas phase outlet of the preheater (2) is communicated with the gas phase inlet of the fixed bed reactor (3), the outlet of the fixed bed reactor (3) is communicated with the inlet of the crude product storage tank (5), the bottom liquid phase outlet of the crude product storage tank (5) is communicated with the top inlet of the first-stage refrigeration separator (11), the bottom outlet of the first-stage refrigeration separator (11) is connected to the top inlet of the second-stage refrigeration separator (13) and the heavy component recovery tank (12), and the bottom outlet of the second-stage refrigeration separator (13) is connected to the light component recovery tank (10) and the product storage tank (14).

3. The continuous preparation device of a hexafluoro-1,3-butadiene intermediate according to claim 1, characterized in that: The secondary condensing equipment comprises a secondary condenser (6), a raw material recovery storage tank (7), a spare secondary condenser (8), and a spare raw material recovery storage tank (9), wherein the top of the raw material recovery storage tank (7) is connected to the secondary condenser (6), and the top of the spare raw material recovery storage tank (9) is connected to the spare secondary condenser (8); The top of the crude product storage tank (5) is connected to the primary condenser (4), the top outlet of the primary condenser (4) is connected to the top inlet of the raw material recovery storage tank (7), and the top outlet of the secondary condenser (6) is connected to the top inlet of the standby raw material recovery storage tank (9); The top outlet of the secondary condenser (6) and the top outlet of the standby secondary condenser (8) are connected to an exhaust gas treatment device; The bottom outlet of the raw material recovery storage tank (7) and the bottom outlet of the standby raw material recovery storage tank (9) are connected to the light component recovery tank (10) and the raw material tank (1).

4. The continuous preparation device of a hexafluoro-1,3-butadiene intermediate according to claim 1, characterized in that: The top inlets of the primary condenser (4), the raw material recovery storage tank (7), the standby raw material recovery storage tank (9), the primary freezing separator (11), and the secondary freezing separator (13) are all provided with a nitrogen pressurizing pipe (27).

5. The continuous preparation device of a hexafluoro-1,3-butadiene intermediate according to claim 1, characterized in that: The crude product storage tank (5), the raw material recovery storage tank (7), and the standby raw material recovery storage tank (9) are all provided with liquid level gauges and vents.

6. The continuous preparation device of hexafluoro-1,3-butadiene intermediate according to claim 1, characterized in that: A flow controller is provided on the connecting pipeline between the raw material tank (1) and the preheater (2).

7. The continuous preparation device of hexafluoro-1,3-butadiene intermediate according to claim 1, characterized in that: The first-stage freezing separator (11) and the second-stage freezing separator (13) include a first shell (15), a second shell (16), a stirring assembly, a discharge pipe (17), a valve (18), and a filter (19). The first shell (15) and the second shell (16) are funnel-shaped structures. The first shell (15) is sleeved on the outside of the second shell (16), and a closed space is formed between the first shell (15) and the second shell (16). The stirring assembly is arranged inside the second shell (16), the discharge pipe (17) is arranged below the second shell (16), and the valve (18) and the filter (19) are arranged on the discharge pipe (17) in sequence from top to bottom.

8. The continuous preparation device of hexafluoro-1,3-butadiene intermediate according to claim 7, characterized in that: The stirring assembly comprises a motor (20), a stirring shaft (21), and a stirring paddle (22); the mounting end of the motor (20) is arranged above the first housing (15); the output shaft of the motor (20) is connected to one end of the stirring shaft (21); the other end of the stirring shaft (21) passes through the first housing (15) and the top of the second housing (16) and extends to the inside of the second housing (16); the stirring paddle (22) is arranged on the stirring shaft (21), and the stirring paddle (22) is arranged inside the second housing (16); A filter cloth (23) is provided in the filter (19).

9. The continuous preparation device of hexafluoro-1,3-butadiene intermediate according to claim 7, characterized in that: A liquid inlet pipe (24) is provided on one side below the first shell (15), and a liquid outlet pipe (25) is provided on the other side above the first shell (15). One end of the liquid inlet pipe (24) and the liquid outlet pipe (25) are connected to the refrigerator, and the other ends of the liquid inlet pipe (24) and the liquid outlet pipe (25) are arranged between the first shell (15) and the second shell (16).

10. The continuous preparation device of hexafluoro-1,3-butadiene intermediate according to claim 7, characterized in that: The top of the second shell (16) is provided with a feed pipe (26), a nitrogen pressure pipe (27), a first sight glass (28) and a second sight glass (29) distributed along the circumference; A vertically arranged liquid level gauge (30) is provided on the outer side of the second shell (16). The top of the liquid level gauge (30) is connected to the top of the second shell (16) through a first liquid level pipe (31), and the bottom of the liquid level gauge (30) is connected to the discharge pipe (17) through a second liquid level pipe (32). The second liquid level pipe (32) is provided above the valve (18).

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