A hexafluoropropylene rectification column double condenser system

Abstract

The present application provides a hexafluoropropylene rectification column double condenser system, which is provided with condenser I and condenser II connected in parallel. After the condenser I and the condenser II are reasonably connected, the method of switching use can make the rectification condensing system not be affected by ice blocking, ensure the continuous operation of the device, and greatly improve the efficiency of preparing hexafluoropropylene. The outlet of the refrigerated brine storage tank is provided with a refrigerated brine pneumatic regulating valve, so that the refrigerated brine output can be effectively controlled, and the temperature in the condenser is prevented from being too high or too low, thereby affecting the use of the condenser.

Description

Technical Field

[0001] The invention belongs to the technical field of organic fluorine chemical production, and in particular relates to a hexafluoropropylene distillation tower double condenser system. Background Art

[0002] Hexafluoropropene (HFP), with the molecular formula CF3CFCF2, is a fundamental raw material in the organic fluorine industry, second only to tetrafluoroethylene in importance. It is a comonomer in numerous fluorinated copolymers and an intermediate in numerous fluorinated compounds. Hexafluoropropene can be prepared via a variety of routes, with the most widely used industrial route being the thermal cracking of tetrafluoroethylene, which offers advantages such as a simple process and high product purity.

[0003] The process flow and principle for producing hexafluoropropylene using thermal cracking of tetrafluoroethylene are as follows: Tetrafluoroethylene and octafluorocyclobutane (a byproduct of tetrafluoroethylene cracking) are preheated in a specific ratio and then fed into a tubular reactor for cracking, converting the mixture into a crude cracked gas. After rapid cooling, carbon removal, alkali washing, water washing, and silica gel dehydration, the crude cracked gas, containing trace amounts of water, enters a distillation system for purification. The overhead condenser uses -35°C chilled brine, operating at temperatures below 0°C. This causes trace amounts of water to freeze on the inner walls of the heat exchange tubes. Over time, this ice can cause severe blockage in the tubes, severely impacting heat exchange efficiency and requiring the entire system to be shut down for defrosting, impacting both production and costs. Summary of the Invention

[0004] The present invention provides a hexafluoropropylene distillation tower double condenser system, which uses a switching method to prevent the distillation and condensation system from being affected by ice blockage, thereby ensuring the continuous operation of the device.

[0005] The present invention adopts the following technical scheme: a hexafluoropropylene distillation tower double condenser system, characterized in that it includes a condenser I and a condenser II, the condenser I and the condenser II are arranged in parallel, a cracked gas input pipe I and an exhaust pipe I are provided on the side of the upper part of the condenser I, a condensed gas output pipe I is provided on the top of the condenser I, a cracked gas input pipe II and an exhaust pipe II are provided on the side of the upper part of the condenser II, a condensed gas output pipe II is provided on the top of the condenser II, a frozen brine input pipe I is provided on the side of the lower part of the condenser I, a frozen brine input pipe II is provided on the side of the lower part of the condenser II, the inlet end of the frozen brine input pipe I and the inlet end of the frozen brine input pipe II are both connected to the outlet of the frozen brine storage tank, the outlet end of the frozen brine input pipe I is connected to the lower part of the condenser I, and the frozen brine is stored in the condenser II. The outlet end of the brine input pipe II is connected with the lower part of the condenser II, and a reflux condensate output pipe I is provided at the bottom of the condenser I, and a reflux condensate output pipe II is provided at the bottom of the condenser II. The reflux condensate output pipe I and the reflux condensate output pipe II are converged together and connected to the port I of the online water analyzer, and the port II of the online water analyzer is connected to the feed port on the side of the distillation tower. The output pipeline connected to the discharge port at the top of the distillation tower is divided into two branches, one of which is connected to the inlet I of the condenser I, and the other branch is connected to the inlet of the condenser II. A condensate output pipe I is also provided on the side of the lower part of the condenser I, and a condensate output pipe II is also provided on the side of the lower part of the condenser II. The condensate output pipe I and the condensate output pipe II are converged into one pipeline and connected to the condensate collection tank.

[0006] The condenser I and condenser II are both configured as vertical shell and tube heat exchangers, wherein the tubes in the vertical shell and tube heat exchangers are made of SS304 and the shell of the vertical shell and tube heat exchanger is made of carbon steel.

[0007] The condensed gas output pipe I is provided with a pressure sensor I and a valve I, and the pressure sensor I is located between the valve I and the top of the condenser I. The condensed gas output pipe II is provided with a pressure sensor II and a valve II, and the pressure sensor II is located between the valve II and the top of the condenser II.

[0008] A frozen brine pneumatic regulating valve is provided at the outlet of the frozen brine storage tank.

[0009] The condensed water collection tank is made of a polypropylene board.

[0010] The cracked gas input pipe I is provided with a valve III, and the cracked gas input pipe II is provided with a valve IV.

[0011] The condensed water output pipe I is provided with a valve V, and the condensed water output pipe II is provided with a valve VI.

[0012] The reflux condensate output pipe I is provided with a valve VII, and the reflux condensate output pipe II is provided with valves VIII and IX.

[0013] The exhaust pipe I is provided with a valve X, and the exhaust pipe II is provided with a valve XI.

[0014] A valve XII is provided on one branch of the output pipeline at the top of the distillation tower, and a valve XIII is provided on the other branch.

[0015] The present invention has the following beneficial effects: By adopting the above technical solution, the present invention provides condensers I and II connected in parallel. After condensers I and II are properly connected, they can be switched in their use method, thereby protecting the distillation and condensing system from ice blockage, ensuring continuous operation of the device and significantly improving the efficiency of hexafluoropropylene production. A pneumatic regulating valve for chilled brine is provided at the outlet of the chilled brine storage tank, effectively controlling the chilled brine output and preventing the condenser from overheating or underheating, which could affect the condenser's operation. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0017] exist Figure 1The present invention provides a double condenser system for a hexafluoropropylene distillation tower, which includes a condenser I1 and a condenser II2. Both condensers I1 and II2 are configured as vertical shell-and-tube heat exchangers, wherein the material of the shells in the vertical shell-and-tube heat exchangers is SS304.The shell of the vertical shell and tube heat exchanger is made of carbon steel. Condenser I1 and condenser II2 are arranged in parallel. A cracked gas input pipe I3 ​​and an exhaust pipe I4 are provided on the side of the upper part of condenser I1. A valve X31 is provided on the exhaust pipe I4. A valve III22 is provided on the cracked gas input pipe I3. A condensed gas output pipe I5 is provided on the top of condenser I1. One end of the condensed gas output pipe I5 is connected to the top of condenser I1, and the other end is connected to the distillation tower 13. A pressure sensor I17 and a valve I18 are provided on the condensed gas output pipe I5. The pressure sensor I17 is located between the valve I18 and the top of condenser I1. A cracked gas input pipe II6 and an exhaust pipe II7 are provided on the side of the upper part of condenser II2. A valve is provided on the exhaust pipe II7. XI32, a valve IV23 is provided on the cracked gas input pipe II6, and a condensed gas output pipe II26 is provided on the top of the condenser II2. One end of the condensed gas output pipe II26 is connected to the top of the condenser II2, and the other end is connected to the distillation tower 13. The condensed gas output pipe II26 is provided with a pressure sensor II19 and a valve II20. The pressure sensor II19 is located between the valve II20 and the top of the condenser II2. A chilled brine input pipe I8 is provided on the lower side of the condenser I1, and a chilled brine input pipe II9 is ​​provided on the lower side of the condenser II2. The inlet end of the chilled brine input pipe I8 and the inlet end of the chilled brine input pipe II9 are both connected to the outlet of the chilled brine storage tank 27. The chilled brine storage tank 27 A chilled brine pneumatic regulating valve 21 is provided at the outlet, the condensed water collecting tank 16 is made of polypropylene board, the outlet end of the chilled brine input pipe Ⅰ8 is connected to the lower part of the condenser Ⅰ1, the outlet end of the chilled brine input pipe Ⅱ9 is connected to the lower part of the condenser Ⅱ2, a reflux condensate output pipe Ⅰ10 is provided at the bottom of the condenser Ⅰ1, a valve Ⅶ28 is provided on the reflux condensate output pipe Ⅰ10, a reflux condensate output pipe Ⅱ11 is provided at the bottom of the condenser Ⅱ2, a valve Ⅷ29 and a valve Ⅸ30 are provided on the reflux condensate output pipe Ⅱ, the reflux condensate output pipe Ⅰ10 and the reflux condensate output pipe Ⅱ are connected to the port Ⅰ of the online water analyzer 12 after being converged, and the port Ⅱ of the online water analyzer 12 is connected to the distillation The feed inlet on the side of tower 13 is connected, and the output pipeline connected to the discharge port at the top of distillation tower 13 is divided into two branches, one of which is connected to inlet I of condenser I1, and the other is connected to the inlet of condenser II2. A valve XII 33 is installed on one branch of the output pipeline at the top of distillation tower 13, and a valve XIII 34 is installed on the other branch. A condensate output pipe I14 is also installed on the side of the lower part of condenser I1, and a valve V24 is installed on the condensate output pipe I14. A condensate output pipe II15 is also installed on the side of the lower part of condenser II2, and a valve VI25 is installed on the condensate output pipe II15. The condensate output pipes I14 and II15 are combined into a pipeline and then connected to the condensate collection tank 16.

[0018] The use process of the present invention is as follows: first, the -35°C frozen brine in the frozen brine storage tank 27 enters the condenser Ⅰ1 through the frozen brine input pipe Ⅰ8 to condense the cracked gas input into the condenser Ⅰ1. The operating temperature in the condenser Ⅰ1 is also below 0°C. After condensation, the condensed cracked gas is discharged from the condensed gas output pipe Ⅰ5 and input into the distillation tower, and the excess waste gas is discharged through the exhaust pipe Ⅰ. The reflux condensate generated in the condenser Ⅰ1 is analyzed for the components in the reflux condensate through the reflux condensate output pipe Ⅰ10 and the online water analyzer 12 and then discharged into the distillation tower 13. The condensed water generated in the condenser Ⅰ1 is input into the condensed water collection tank 16 through the condensed water output pipe Ⅰ14 for collection and standby use. After the above operation, the condensation of the cracked gas is completed. However, this will cause the inner wall of the shell of the condenser Ⅰ1 to freeze after use, and the tubes in the shell will be blocked by ice. The tubes in the condenser must be cleaned. In order to ensure normal operation in the process of producing hexafluoropropylene by cracking tetrafluoroethylene To condense the cracked gas, when cleaning the condenser, condenser II2 can be used to perform condensation treatment according to the process. First, the -35°C frozen brine in the frozen brine storage tank 27 enters the condenser II2 through the frozen brine input pipe II9 to condense the cracked gas input into the condenser II2. The operating temperature in the condenser II2 is also below 0°C. After condensation, the condensed cracked gas is discharged from the condensed gas output pipe II26 and input into the distillation tower 13, and the excess waste gas is discharged through the exhaust pipe II7. The reflux condensate generated in the condenser II2 is analyzed by the reflux condensate output pipe II11 and the online water analyzer 12 for the components in the reflux condensate and then discharged into the distillation tower 13. The condensed water generated in the condenser II2 is input into the condensed water collection tank 16 through the condensed water output pipe II15 for collection and standby. If the condenser II2 is also blocked by ice, the condenser I1 that has been cleaned can be started. During the entire switching process, the pipeline is opened and closed by controlling the valve.

Claims

1. A hexafluoropropylene distillation tower double condenser system, characterized in that It comprises a condenser I (1) and a condenser II (2), which are arranged in parallel. A cracked gas inlet pipe I (3) and an exhaust pipe I (4) are provided on the side of the upper part of the condenser I (1), a condensed gas outlet pipe I (5) is provided on the top of the condenser I (1), a cracked gas inlet pipe II (6) and an exhaust pipe II (7) are provided on the side of the upper part of the condenser II (2), a condensed gas outlet pipe II (26) is provided on the top of the condenser II (2), and a condensed gas outlet pipe II (27) is provided on the lower part of the condenser I (1). A frozen brine input pipe I (8) is provided on the side, and a frozen brine input pipe II (9) is provided on the lower side of the condenser II (2). The inlet end of the frozen brine input pipe I (8) and the inlet end of the frozen brine input pipe II (9) are both connected to the outlet of the frozen brine storage tank (27). The outlet end of the frozen brine input pipe I (8) is connected to the lower part of the condenser I (1), and the outlet end of the frozen brine input pipe II (9) is connected to the lower part of the condenser II (2). A reflux condenser is provided at the bottom of the condenser I (1). The reflux condensate output pipe I (10) is provided at the bottom of the condenser II (2). The reflux condensate output pipe I (10) and the reflux condensate output pipe II (11) are connected to the port I of the online water analyzer (12) after being converged. The port II of the online water analyzer (12) is connected to the feed port on the side of the distillation tower (13). The output pipe connected to the discharge port on the top of the distillation tower (13) is divided into two branches, one of which is connected to the inlet I of the condenser I (1) and the other is connected to the inlet I of the condenser I (1). The branch is connected to the inlet of condenser II (2). A condensate output pipe I (14) is provided on the side of the lower part of condenser I (1), and a condensate output pipe II (15) is provided on the side of the lower part of condenser II (2). The condensate output pipe I (14) and the condensate output pipe II (15) are combined into a pipeline and then connected to the condensate collecting tank (16). The condenser I (1) and the condenser II (2) are both configured as vertical shell and tube heat exchangers, wherein the material of the shell and tube in the vertical shell and tube heat exchanger is SS304.The shell of the vertical shell and tube heat exchanger is made of carbon steel. The condensed gas output pipe I (5) is provided with a pressure sensor I (17) and a valve I (18). The pressure sensor I (17) is located between the valve I (18) and the top of the condenser I (1). The condensed gas output pipe II (26) is provided with a pressure sensor II (19) and a valve II (20). The pressure sensor II (19) is located between the valve II (20) and the top of the condenser II (2). The outlet of the frozen brine storage tank (27) is provided with a frozen brine pneumatic regulating valve (21). The condensed water collecting tank (16) is made of a polypropylene board. When the -35°C frozen brine in the frozen brine storage tank (27) is Water enters the condenser I (1) through the frozen brine input pipe I (8) to condense the cracked gas input into the condenser I (1). After condensation, the condensed cracked gas is discharged from the condensed gas output pipe I (5) and input into the distillation tower (13), and the excess waste gas is discharged through the exhaust pipe I (4). When the -35°C frozen brine in the frozen brine storage tank (27) enters the condenser II (2) through the frozen brine input pipe II (9) to condense the cracked gas input into the condenser II (2). After condensation, the condensed cracked gas is discharged from the condensed gas output pipe II (26) and input into the distillation tower (13), and the excess waste gas is discharged through the exhaust pipe II (7).

2. The hexafluoropropylene distillation tower double condenser system according to claim 1, characterized in that The cracked gas input pipe I (3) is provided with a valve III (22), and the cracked gas input pipe II (6) is provided with a valve IV (23).

3. The hexafluoropropylene distillation tower double condenser system according to claim 1, characterized in that The condensate output pipe I (14) is provided with a valve V (24), and the condensate output pipe II (15) is provided with a valve VI (25).

4. The hexafluoropropylene distillation tower double condenser system according to claim 1, characterized in that The reflux condensate output pipe I (10) is provided with a valve VII (28), and the reflux condensate output pipe II is provided with a valve VIII (29) and a valve IX (30).

5. The hexafluoropropylene distillation tower double condenser system according to claim 1, characterized in that The exhaust pipe I (4) is provided with a valve X (31), and the exhaust pipe II (7) is provided with a valve XI (32).

6. The hexafluoropropylene distillation tower double condenser system according to claim 1, characterized in that A valve XII (33) is provided on one branch of the output pipeline at the top of the distillation tower (13), and a valve XIII (34) is provided on the other branch.

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