Continuous and safe production system for preparing hexafluoropropylene

Abstract

The invention provides a continuous and safe production system for preparing hexafluoropropylene, which is characterized in that the output end of a cracking reaction kettle (4) is respectively communicated with a feeding hole in the bottom of a cracking gas collecting buffer tank I (1) of a main buffer tank and a feeding hole in the bottom of a cracking gas collecting buffer tank II (2) of a standby buffer tank; a discharge hole in the upper part of the pyrolysis gas collecting buffer tank I (1) and a discharge hole in the upper part of the pyrolysis gas collecting buffer tank II (2) are converged into a pipeline and then are communicated with a feed hole of a hexafluoroethylene storage tank (12) through a cooling device (5) and a filtering device in sequence, and a discharge hole of the hexafluoroethylene storage tank (12) is communicated with a rectifying tower (13) for producing hexafluoroethylene; a discharging port II (14) of the filtering device is communicated with a feeding port of the directional pulse blowback system (3), a discharging port of the directional pulse blowback system (3) is communicated with the waste collecting tank (7), and safe, continuous and normal operation of hexafluoropropylene preparation can be guaranteed.

Description

Technical Field

[0001] The invention relates to a safety device for preparing hexafluoropropylene, in particular to a system for continuous safe production in preparing hexafluoropropylene. Background Art

[0002] Hexafluoropropene (HFP), with the molecular formula CF3CFCF2, is one of the basic raw materials of organic fluorine industry, second only to tetrafluoroethylene in importance. It is a comonomer of many fluorine-containing copolymers and an intermediate of many fluorine-containing compounds. There are many ways to prepare hexafluoropropene, and the industrial production of hexafluoropropene is widely adopted by the thermal cracking route of tetrafluoroethylene, which has the advantages of simple process and high product purity. At present, hexafluoropropylene is commonly produced by thermal cracking of tetrafluoroethylene. The production process is as follows: tetrafluoroethylene and octafluorocyclobutane (a by-product of tetrafluoroethylene cracking) are preheated in a certain ratio and then enter a tubular reactor for cracking and conversion into cracked gas. After the cracked gas is rapidly cooled, filtered, washed with alkali, washed with water, and dehydrated with silica gel, the cracked gas containing trace amounts of water enters the distillation system for purification. However, this reaction system is a simple extensive filtration system, which is insufficient to filter small-diameter particles. Over time, the accumulation is serious and the production system is blocked, resulting in a high system pressure difference, which makes it impossible to operate and must be stopped for cleaning, affecting the operating rate of the device. At the same time, it also brings certain safety risks. Combined with the toxic and harmful characteristics of the hexafluoropropylene production process, it not only affects the production time, but also has certain safety risks when inspecting and cleaning the equipment. Summary of the invention

[0003] The invention provides a system for continuous safe production in the preparation of hexafluoropropylene, which can ensure the safe, continuous and normal operation of the preparation of hexafluoropropylene.

[0004] The present invention adopts the following technical scheme: a system for continuous safe production in the preparation of hexafluoropropylene, which comprises a cracking gas collecting buffer tank I, a cracking gas collecting buffer tank II and a directional pulse backwashing system, wherein the output end of the cracking reactor is divided into two pipelines which are respectively connected with a feed port at the bottom of the cracking gas collecting buffer tank I and a feed port at the bottom of the cracking gas collecting buffer tank II, wherein the cracking gas collecting buffer tank I is a main buffer tank, and the cracking gas collecting buffer tank II is a standby buffer tank, and the discharge port at the top of the cracking gas collecting buffer tank I and the discharge port at the top of the cracking gas collecting buffer tank II are collected into one pipeline and then sequentially connected with the feed port of the filtering device through a cooling device, the discharge port I of the filtering device is connected with the feed port of a hexafluoroethylene storage tank, the discharge port of the hexafluoroethylene storage tank is connected with a distillation tower for hexafluoroethylene production, the discharge port II of the filtering device is connected with the feed port of the directional pulse backwashing system, and the discharge port of the directional pulse backwashing system is connected with a waste collection tank.

[0005] Furthermore, the tank bodies of the cracked gas collection buffer tank I and the cracked gas collection buffer tank II are both made of Q235 steel.

[0006] Furthermore, the tank bodies of the cracked gas collection buffer tank I and the cracked gas collection buffer tank II are both provided with spoilers, and the inner walls of the tank bodies of the cracked gas collection buffer tank I and the cracked gas collection buffer tank II are both installed with pressure sensors and temperature sensors.

[0007] Furthermore, the cooling device is configured as a reaction heat converter, and the cooling is performed after conversion by the medium water in the reaction heat converter.

[0008] Furthermore, the filtering device is configured as a precision membrane filter, which includes a filtering chamber, in which a filtering membrane is arranged, and the filtering membrane divides the inner part of the filtering chamber into an upper gas storage chamber and a lower impurity storage chamber, and the discharge port I is located on the upper gas storage chamber, and the discharge port II is located on the impurity storage chamber.

[0009] Furthermore, the filter membrane is a polytetrafluoroethylene membrane or a polyvinylidene fluoride membrane.

[0010] Further, the directional pulse backflush system is configured as a pulse backflush bag filter.

[0011] The present invention has the following beneficial effects: after adopting the above technical scheme, the present invention performs buffering and decompression of gas through a cracked gas collection buffer tank, and then performs filtering treatment on hexafluoropropylene through a precision membrane filter, and continuously performs purging treatment on high-boiling substances and particulate matter through a directional pulse backflush system, which can not only avoid the blockage of the distillation tower caused by the blockage of the filler by the particulate matter and the high-boiling substances, but also eliminate the need to stop the production process to clean the particulate matter and the high-boiling substances, reduce or even eliminate the frequency of contact with toxic and harmful substances, and ensure the safe and continuous normal operation of the preparation of hexafluoropropylene. The present invention combines gas buffering, precision membrane filters, and directional pulse backflush systems. The pulse backflush system and its supporting collection system stabilize the intake pressure through the cracking gas collection buffer tank, improve the efficiency of impurity cleaning through precise filtration, timed, constant pressure and quantitative system backflush and collection system, monitor the operating status of the system through pressure sensors and temperature sensors, and improve the buffer tank pressure in time, further improving the safety of continuous operation. In addition, the cracking gas collection buffer tank I and the cracking gas collection buffer tank II are switched and continuously recycled to achieve the quality of safe and continuous operation of the device, solving the problems of long-term high load, high unit consumption and high risk in maintenance in the production process of hexafluoropropylene. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0014] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying 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.

[0015] exist Figure 1The present invention provides a system for continuous safe production in the preparation of hexafluoropropylene, which comprises a cracking gas collecting buffer tank Ⅰ1 and a cracking gas collecting buffer tank Ⅱ2 and a directional pulse backflush system 3. The output end of the cracking reactor 4 is divided into two pipelines which are respectively connected to the feed inlet at the bottom of the cracking gas collecting buffer tank Ⅰ1 and the feed inlet at the bottom of the cracking gas collecting buffer tank Ⅱ2. A switch valve Ⅰ is provided at the feed inlet at the bottom of the cracking gas collecting buffer tank Ⅰ1, and a switch valve Ⅱ is provided at the feed inlet at the bottom of the cracking gas collecting buffer tank Ⅱ2. The cracking gas collecting buffer tank Ⅰ1 is a main buffer tank, and the cracking gas collecting buffer tank Ⅱ2 is a The standby buffer tank, the discharge port at the top of the cracked gas collection buffer tank Ⅰ1 and the discharge port at the top of the cracked gas collection buffer tank Ⅱ2 are collected into a pipeline and then sequentially connected to the feed port of the filter device through the cooling device 5, the discharge port Ⅰ11 of the filter device is connected to the feed port of the hexafluoroethylene storage tank 12, the discharge port of the hexafluoroethylene storage tank 12 is connected to the distillation tower 13 for hexafluoroethylene production, the discharge port Ⅱ14 of the filter device is connected to the feed port of the directional pulse backflush system 3, the discharge port of the directional pulse backflush system 3 is connected to the waste collection tank 7, the tank body of the cracked gas collection buffer tank Ⅰ1 and the cracked gas collection buffer tank Ⅱ2 used in this embodiment are connected to the feed port of the hexafluoroethylene storage tank 12, the discharge port of the hexafluoroethylene storage tank 12 is connected to the distillation tower 13 for hexafluoroethylene production, the discharge port Ⅱ14 of the filter device is connected to the feed port of the directional pulse backflush system 3, and the discharge port of the directional pulse backflush system 3 is connected to the waste collection tank 7. The tank bodies of the cracked gas collection buffer tank Ⅱ2 are both made of Q235 steel. The tank bodies of the cracked gas collection buffer tank Ⅰ1 and the cracked gas collection buffer tank Ⅱ2 used in this embodiment are both provided with spoilers 8. Pressure sensors 9 and temperature sensors 10 are installed on the inner walls of the tank bodies of the cracked gas collection buffer tank Ⅰ1 and the inner walls of the tank bodies of the cracked gas collection buffer tank Ⅱ2. The cooling device 5 used in this embodiment is set as a reaction heat converter, which is cooled after conversion by the medium water in the reaction heat converter. The filtering device used in this embodiment is set as a precision membrane filter 6, which includes a filtering chamber 15, a filtering chamber 16, and a filtering chamber 17. A filter membrane 16 is provided in the chamber 15, and the filter membrane 16 divides the interior of the filter chamber 15 into an upper gas storage chamber 17 and a lower impurity storage chamber 18. The discharge port Ⅰ11 is located on the upper gas storage chamber 17, and the discharge port Ⅱ14 is located on the impurity storage chamber 18. The filter membrane 16 is a polytetrafluoroethylene membrane or a polyvinylidene fluoride membrane. In this embodiment, the filter membrane 16 preferably adopts a polytetrafluoroethylene membrane. The directional pulse backblowing system 3 is configured as a pulse backblowing bag dust collector. A closed air supply system is connected to the guide pipe of the pulse backblowing bag dust collector. The closed air supply system provides high-pressure gas to the pulse backblowing bag dust collector.

[0016] The use process of the present invention is as follows: the present invention puts tetrafluoroethylene into a cracking reactor 4 for cracking to obtain hexafluoroethylene, opens the switch valve I, and allows the hexafluoroethylene gas obtained after cracking to enter the cracking gas collection buffer tank I1 as the main buffer tank from the bottom feed port from bottom to top, and performs downward pressure treatment on the inflowing gas through the spoiler 8 to stabilize the pressure of the incoming gas. The other cracking gas collection buffer tank II2 is a spare buffer tank, and the cracking gas collection buffer tank I1 and the cracking gas collection buffer tank II2 are switched for use. In order to meet the explosion-proof requirements, a pressure sensor 9 and a temperature sensor 10 are used to monitor the pressure and temperature of the gas in the cracking gas collection buffer tank I1, and then the stabilized gas enters the reaction heat converter from the upper discharge port of the cracking gas collection buffer tank I1, and is cooled after conversion by the medium water in the reaction heat converter, and then the cooled hexafluoroethylene gas is discharged into the precision membrane filter 6 for filtration, and the precision membrane filter 6 utilizes the membrane The microporous structure is used for filtering, and the filtered hexafluoroethylene gas is directly discharged into the hexafluoroethylene storage tank 12 through the discharge port Ⅰ11 for storage, and finally discharged into the distillation tower 13 for distillation treatment. The high-boiling substances and particulate matter generated after cracking are filtered through the precision membrane filter 6. The pulse backwash bag dust collector is backwashed at a fixed time, pressure and quantity to blow the continuously generated and accumulated high-boiling substances and particulate matter into the waste collection tank 7 for collection, thereby effectively avoiding the impurities brought into the distillation preparation of hexafluoroethylene to block the distillation tower 13, thereby achieving continuous and safe production of hexafluoropropylene. During the purging process, the closed gas supply system provides high-pressure gas to the pulse backwash bag dust collector. When the pressure and temperature in the cracking gas collection buffer tank Ⅰ1 are monitored to be too high and do not meet the explosion-proof requirements, the switch valve Ⅰ of the cracking gas collection buffer tank Ⅰ1 can be closed, and the switch valve Ⅱ of the cracking gas collection buffer tank Ⅱ2 can be switched to open, and the cracking gas collection buffer tank Ⅱ2 is used for gas buffering treatment.

[0017] Without limitation to this, any changes or substitutions that are not conceived through creative work should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined in the claims.

Claims

1. A system for continuous safe production in the preparation of hexafluoropropylene, characterized in that It comprises a cracking gas collecting buffer tank I (1), a cracking gas collecting buffer tank II (2) and a directional pulse backflush system (3). The output end of the cracking reactor (4) is divided into two pipelines which are respectively connected to a feed inlet at the bottom of the cracking gas collecting buffer tank I (1) and a feed inlet at the bottom of the cracking gas collecting buffer tank II (2). The cracking gas collecting buffer tank I (1) is a main buffer tank, the cracking gas collecting buffer tank II (2) is a standby buffer tank, and the discharge port at the top of the cracking gas collecting buffer tank I (1) and the cracking gas collecting buffer tank II (2) are connected to the feed inlet at the bottom of the cracking gas collecting buffer tank I (1). The discharge ports at the top of tank II (2) are combined into a pipeline and then sequentially pass through a cooling device (5) to be connected to a feed port of a filtering device. The discharge port I (11) of the filtering device is connected to a feed port of a hexafluoroethylene storage tank (12). The discharge port of the hexafluoroethylene storage tank (12) is connected to a distillation tower (13) for producing hexafluoroethylene. The discharge port II (14) of the filtering device is connected to a feed port of a directional pulse backflush system (3). The discharge port of the directional pulse backflush system (3) is connected to a waste collection tank (7).

2. The system for continuous safe production in the preparation of hexafluoropropylene according to claim 1, characterized in that The tank bodies of the cracked gas collection buffer tank I (1) and the tank bodies of the cracked gas collection buffer tank II (2) are both made of Q235 steel.

3. The system for continuous safe production in the preparation of hexafluoropropylene according to claim 1, characterized in that The tank bodies of the cracked gas collecting buffer tank I (1) and the tank bodies of the cracked gas collecting buffer tank II (2) are both provided with spoilers (8), and the inner walls of the tank bodies of the cracked gas collecting buffer tank I (1) and the inner walls of the tank bodies of the cracked gas collecting buffer tank II (2) are both provided with pressure sensors (9) and temperature sensors (10).

4. The system for continuous and safe preparation of hexafluoropropylene according to claim 1, characterized in that The cooling device (5) is configured as a reaction heat converter, and is cooled after conversion by medium water in the reaction heat converter.

5. The system for continuous safe production in the preparation of hexafluoropropylene according to claim 1, characterized in that The filtering device is configured as a precision membrane filter (6), the precision membrane filter (6) comprising a filtering chamber (15), a filtering membrane (16) being arranged in the filtering chamber (15), the filtering membrane (16) dividing the interior of the filtering chamber (15) into an upper gas storage chamber (17) and a lower impurity storage chamber (18), the discharge port I (11) being located on the upper gas storage chamber (17), and the discharge port II (14) being located on the impurity storage chamber (18).

6. The system for continuous safe production in the preparation of hexafluoropropylene according to claim 5, characterized in that The filter membrane (16) is a polytetrafluoroethylene membrane or a polyvinylidene fluoride membrane.

7. The system for continuous safe production in the preparation of hexafluoropropylene according to claim 1, characterized in that The directional pulse backflush system (3) is configured as a pulse backflush bag filter.

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