Horizontal kettle for fluororesin reaction

Abstract

The utility model belongs to the technical field of fluororesin reaction equipment, and particularly relates to a horizontal kettle for fluororesin reaction, which comprises a kettle body, a stirring mechanism and a shaft seal device, the kettle body comprises a straight cylinder section and sealing heads fixedly connected to the front end and the rear end of the straight cylinder section; the shaft seal device comprises a front-end mechanical seal device, a rear-end mechanical seal device, a front-end balance liquid tank and a rear-end balance liquid tank; the front-end mechanical seal device and the rear-end mechanical seal device are respectively mounted on the two seal heads; the stirring mechanism comprises a stirring shaft, the stirring shaft is rotationally supported on the kettle body through a front-end mechanical sealing device and a rear-end mechanical sealing device, and two ends of the stirring shaft respectively extend out of the kettle body. According to the utility model, plasticized materials can be effectively prevented from being formed at the front-end mechanical sealing device and the rear-end mechanical sealing device due to self-aggregation of PVDF, and the front-end mechanical sealing device or the rear-end mechanical sealing device is prevented from being damaged due to non-uniform force load in the kettle body on the stirring shaft.

Description

TECHNICAL FIELD

[0001] The utility model belongs to fluororesin reaction equipment technical field, concretely relates to a horizontal kettle for fluororesin reaction. BACKGROUND

[0002] Emulsion polymerization method is one of the methods widely used in the production of fluororesin, and horizontal kettle is usually used in emulsion polymerization kettle. Fluororesin polymerization reaction is an exothermic reaction, and the heat generated during the reaction needs to be quickly removed by the stirring system. The mechanical shearing action of stirring can cause emulsion demulsification, affecting product unit consumption and quality.

[0003] CN217189594U discloses a PVDF polymerization kettle, which comprises a kettle body and a transmission stirring device. The kettle body is a horizontal kettle body, which can realize the purpose of bringing gas-phase monomers into liquid-phase medium at a low speed. Compared with vertical kettle, the stirring rate of horizontal kettle is much lower, and the shearing action is very weak, which has a positive effect on emulsion stability. Under the protection of emulsifier, polymer particles can easily grow stably, which not only can prepare emulsion with high solid content, but also can reduce the amount of emulsifier. The transmission stirring device comprises a stirring shaft rotatably supported on the kettle body, a screw belt stirrer and an anchor stirrer mounted on the stirring shaft. The screw belt stirrer is located in the middle of the kettle body and is used to stir the material in the middle of the kettle body. The anchor stirrer is two, and the two anchor stirrers are respectively located on both sides of the screw belt stirrer. The two anchor stirrers correspond to the two ends of the kettle body, so that the two anchor stirrers respectively stir the material in the two ends of the kettle body. One end of the stirring shaft is supported on the sliding sealing bearing, and the other end of the stirring shaft extends outward through the mechanical sealing structure. The PVDF polymerization kettle further comprises a balance tank, which contains lubricating oil. The lubricating oil cavity in the balance tank is in communication with the lubricating oil cavity in the mechanical sealing structure through a pipeline, so that the pressure of the lubricating oil cavity in the mechanical sealing structure can be adjusted through the balance tank, thereby ensuring that the pressure of the lubricating oil cavity in the mechanical sealing structure remains consistent, and the sealing performance of the mechanical sealing structure is maintained, and the sealing performance of the stirring shaft and the kettle body is maintained. The PVDF polymerization kettle has the following technical problems: (1) only one end of the kettle body is provided with a mechanical sealing structure, and the other end is provided with a sliding sealing bearing. For the end provided with the sliding sealing bearing, the PVDF emulsion will enter the sliding sealing bearing. The PVDF emulsion will be demulsified and self-aggregated to form plastic material under the friction of the stirring shaft and the sliding sealing bearing. The hard plastic material will damage the sliding sealing bearing and hinder the rotation of the stirring shaft. In addition, since the end connected with the sliding sealing bearing is located in the kettle body, the high-pressure reaction medium in the kettle body will generate a large axial force on the stirring shaft (CN217189594U, Figure 2). Figure 1The part of the stirring shaft connected with the mechanical seal structure is not subjected to the axial force of the reaction medium in the kettle body, which causes the two ends of the stirring shaft to be subjected to uneven force load, and further causes the end of the stirring shaft connected with the mechanical seal structure to be damaged. (2) The pressure in the kettle body is real-time changeable, and generally needs to ensure that the pressure in the mechanical seal structure is slightly higher than the pressure in the kettle body. The PVDF polymerization kettle cannot acquire the pressures in the kettle body and the mechanical seal structure in real time and adjust, and cannot ensure the sealing performance of the mechanical seal device. Content of the utility model

[0004] The utility model discloses to the above prior art's insufficient, provide a kind of for fluorine resin reaction's horizontal kettle, stirring shaft is rotatably supported in kettle body by front end mechanical seal device and rear end mechanical seal device, and the two ends of stirring shaft extend to kettle body outside respectively, to effectively prevent the plasticizing material formed at front end mechanical seal device and rear end mechanical seal device due to PVDF self-polymerization, and prevent the front end mechanical seal device or rear end mechanical seal device damage caused by the uneven force load in kettle body.

[0005] The utility model provides a kind of for fluorine resin reaction's horizontal kettle, including kettle body, stirring mechanism and shaft seal device;The kettle body includes straight cylinder section and the head fixedly connected to the front and rear ends of straight cylinder section;The shaft seal device includes front end mechanical seal device, rear end mechanical seal device, front end balance liquid tank and rear end balance liquid tank, and the front end mechanical seal device and rear end mechanical seal device are respectively installed on two the head, and the front end balance liquid tank is connected with front end mechanical seal device by pipeline, and the rear end balance liquid tank is connected with rear end mechanical seal device by pipeline;The stirring mechanism includes stirring shaft, and the stirring shaft is rotatably supported in kettle body by front end mechanical seal device and rear end mechanical seal device, and the two ends of the stirring shaft extend to kettle body outside respectively.

[0006] By the above technical scheme, the technical scheme provided by the utility model at least has following advantages: stirring shaft is rotatably supported in kettle body by front end mechanical seal device and rear end mechanical seal device, to effectively prevent front end mechanical seal device and rear end mechanical seal device due to PVDF self-polymerization and hinder stirring shaft rotation;And the two ends of stirring shaft extend to kettle body outside respectively, so that the two ends of stirring shaft are subjected to uniform force load, prevent the front end mechanical seal device or rear end mechanical seal device damage caused by the uneven force load in kettle body.

[0007] Further, the shaft seal balancing system comprises a mechanical seal liquid tank, a mechanical seal water pump, an in-kettle pressure sensor, a front-end balancing liquid tank pressure sensor, a front-end balancing liquid tank water inlet electromagnetic valve, a front-end balancing liquid tank pressure relief valve, a rear-end balancing liquid tank pressure sensor, a rear-end balancing liquid tank water inlet electromagnetic valve, a rear-end balancing liquid tank pressure relief valve and a control system; the mechanical seal liquid tank, the mechanical seal water pump, the front-end balancing liquid tank water inlet electromagnetic valve, the front-end balancing liquid tank and the front-end balancing liquid tank pressure relief valve are sequentially connected through pipelines and form a circulation loop, and the mechanical seal liquid tank, the mechanical seal water pump, the rear-end balancing liquid tank water inlet electromagnetic valve, the rear-end balancing liquid tank and the rear-end balancing liquid tank pressure relief valve are sequentially connected through pipelines and form a circulation loop; the mechanical seal water pump, the in-kettle pressure sensor, the front-end balancing liquid tank pressure sensor, the front-end balancing liquid tank water inlet electromagnetic valve, the front-end balancing liquid tank pressure relief valve, the rear-end balancing liquid tank pressure sensor, the rear-end balancing liquid tank water inlet electromagnetic valve and the rear-end balancing liquid tank pressure relief valve are connected with the control system; the in-kettle pressure sensor is used to acquire the pressure in the kettle body, the front-end balancing liquid tank pressure sensor is used to detect the pressure in the front-end balancing liquid tank, and the rear-end balancing liquid tank pressure sensor is used to detect the pressure in the rear-end balancing liquid tank. By the shaft seal balancing system, the pressure in the kettle body, the pressure in the front-end balancing liquid tank and the pressure in the rear-end balancing liquid tank can be monitored in real time, and the front-end balancing liquid tank and the rear-end balancing liquid tank can be pressurized or depressurized in time according to the pressure monitoring results, so as to ensure the sealing property of the shaft seal device.

[0008] Further, the stirring mechanism further comprises a ribbon stirrer and an anchor stirrer, both of which are fixedly installed on the stirring shaft, the ribbon stirrer is located at the middle part of the kettle body, and the two anchor stirrers are respectively located at the two ends of the kettle body. The ribbon stirrer can increase the radial flow in the kettle body and generate large back pressure, so as to bring more fluorine-containing olefins in the gas phase into the liquid phase. Meanwhile, the ribbon stirrer can also generate axial flow, so as to improve the mixing effect between the liquid phases. The anchor stirrer can quickly stir the liquid pushed by the ribbon stirrer to the head, so as to avoid the heat accumulation of the material at the head, especially the demulsification plasticization of the shaft seal device caused by the interaction of heat accumulation and mechanical shearing at the shaft seal device. The anchor stirrer and the ribbon stirrer work together, so that the fluorine-containing olefins in the gas phase in the kettle body are more easily brought into the liquid phase space, the stirring and mixing effect in the liquid phase is good, there is no flow dead zone (local space in the flow system, the fluid in the space basically does not participate in the main fluid flow, only makes local movement in place) in the kettle body, and the local heat accumulation causing emulsion breaking is avoided.

[0009] Preferably, the ribbon stirrer comprises 4-6 helical belts arranged in staggered manner, the ratio of the diameter of the ribbon stirrer to the inner diameter of the kettle body is 0.95-0.98, the ratio of the width of the helical belt to the inner diameter of the kettle body is 0.05-0.1, and the helical pitch angle of the helical belt is 90°-180°.

[0010] Preferably, the anchor stirrer comprises 2-4 arc-shaped flat paddle blades connected in sequence, the outer edge shape of at least part of the arc-shaped flat paddle blades is consistent with the shape of the inner wall surface of the corresponding side head, and the distance between the part of the arc-shaped flat paddle blades and the inner wall surface of the corresponding side head is 30-50 mm; the ratio of the diameter of the anchor stirrer to the inner diameter of the kettle body is 0.5-0.85, and the ratio of the width of the arc-shaped flat paddle blade to the inner diameter of the kettle body is 0.05-0.08.

[0011] Preferably, the length-diameter ratio of the kettle body is 1.8-2.

[0012] Further, the flushing system comprises a flushing water tank, a flushing water pump, a rotary joint and flushing nozzles, the stirring shaft is a hollow structure, a plurality of flushing nozzles are arranged on the stirring shaft along the axial direction of the stirring shaft, the flushing nozzles are in communication with the inner cavity of the stirring shaft, the rotary joint is connected to one end of the stirring shaft and in communication with the inner cavity of the stirring shaft, and the flushing water tank, the flushing water pump and the rotary joint are connected in sequence by pipelines. When the kettle needs to be cleaned, the flushing water pump pumps the flushing water in the flushing water tank into the stirring shaft, and the flushing water is sprayed out through the flushing nozzles to flush the powders adhered to the inner wall of the kettle body and the stirring mechanism.

[0013] Further, the inner wall of the straight cylinder section is provided with an inner jacket, the inner wall thickness of the inner jacket is less than the wall thickness of the straight cylinder section, the inner jacket is provided with a rib plate, and the rib plate is fixedly connected with the inner wall of the inner jacket and the wall surface of the straight cylinder section. By adopting the technical scheme, on the one hand, the inner wall of the inner jacket can be directly in contact with the reaction system, and since the inner wall thickness of the inner jacket is less than the wall thickness of the straight cylinder section, the thermal resistance between the cold / hot medium in the inner jacket and the reaction system in the kettle body can be reduced, and the heat transfer coefficient can be improved; on the other hand, the inner wall of the inner jacket can conduct the high pressure in the kettle body to the wall surface of the straight cylinder section through the rib plate, and the pressure resistance of the inner wall of the inner jacket can be ensured.

[0014] Further, the straight cylinder section is provided with an inner jacket cooling water inlet, an inner jacket cooling water outlet, an inner jacket steam inlet and an inner jacket condensate water outlet which are in communication with the inner jacket. If steam and cooling water share one pipe for inlet and outlet, problems such as steam impact on the pipe, water hammer when switching medium and the like are likely to occur. Therefore, the inner jacket cooling water inlet, the inner jacket cooling water outlet, the inner jacket steam inlet and the inner jacket condensate water outlet are arranged on the straight cylinder section to realize the separate pipe inlet and outlet of steam and cooling water.

[0015] Further, the kettle body is provided with two gas inlets, and the two gas inlets are respectively located on the front and rear sides of the kettle body. The gas inlets are used for adding pure water, dispersing agent, gas phase fluorine-containing olefin monomer and the like into the kettle body. The gas phase fluorine-containing olefin monomer is added into the kettle body through the two gas inlets respectively located on the front and rear sides of the kettle body, which is beneficial to the dispersion of the gas phase fluorine-containing olefin monomer in the kettle body. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the horizontal reactor used for the fluoropolymer reaction in Example 1.

[0017] Figure 2 This is a schematic diagram of the horizontal reactor used for the fluoropolymer reaction in Example 2.

[0018] The components are: 1-reducer, 2-frame, 3-coupling, 4-front mechanical seal, 5-front balance tank pressure relief valve, 6-front balance tank, 7-front balance tank pressure sensor, 8-front anchor agitator, 9-front head jacket cooling water outlet, 10-inner jacket cooling water outlet, 11-cabin internal pressure sensor, 12-front air inlet, 13-safety vent, 14-ribbon agitator, 15-rear air inlet, 16-agitator fixing rod, 17-inner jacket steam inlet, 18-rear head jacket cooling water outlet, 19-rear anchor agitator, 20-rear balance tank pressure sensor, 21-rear balance tank, 22-rear balance tank pressure relief valve, 23-rear mechanical seal. 24-Rotary joint, 25-Flush water pipe, 26-Flush water pump, 27-Rear end balance tank pressure relief pipe, 28-Flush water tank, 29-Rear end cap jacket cooling water inlet, 30-Inner jacket cooling water inlet, 31-Discharge port, 32-Inner jacket condensate outlet, 33-Front end cap jacket cooling water inlet, 34-Mechanical seal liquid tank, 35-Mechanical seal water pump, 36-Rear end balance tank inlet solenoid valve, 37-Front end balance tank inlet solenoid valve, 38-Front end balance tank pressure relief pipe, 39-Rear end balance tank inlet pipe, 40-Front end balance tank inlet pipe, 41-Flush nozzle, 42-Bottle body, 43-Inner jacket, 44-Agitator shaft, 45-Initiator port, 46-Fir plate, 47-Flange flange. Detailed Implementation

[0019] The following embodiments are further illustrations of this utility model, but the utility model is not limited thereto. In this utility model, "front," "rear," "front end," and "rear end" only indicate relative positions.

[0020] Example 1

[0021] Figure 1 Embodiment 1 of the present invention is shown.

[0022] The horizontal kettle for fluororesin reaction provided by the embodiment is used for producing fluororesin by the emulsion method, and is used for emulsion polymerization of fluorine-containing olefin monomers (such as vinylidene fluoride, tetrafluoroethylene, tetrafluoroethylene and hexafluoropropylene mixture, etc.) as main reaction monomers in water solution under the action of initiators, molecular weight regulators, dispersants and other additives. According to different fluororesins, the reaction pressure and the reaction temperature are different, the reaction pressure ranges from 1.0 to 5.0 Mpa, and the reaction temperature ranges from 50 to 150 DEG C. After the reaction is completed, a stable water emulsion is obtained.

[0023] As shown in Figure 1 A horizontal kettle for fluororesin reaction includes a kettle body 42, a stirring mechanism and a shaft sealing device.

[0024] The kettle body 42 is provided with a gas inlet, an initiator inlet 45, a discharge port 31 and a safety relief port 13. The gas inlet is used for adding pure water, dispersants, gas-phase fluorine-containing olefin monomers and other materials into the kettle body 42. In the embodiment, the kettle body 42 is provided with two gas inlets, and the two gas inlets are respectively located at the front and rear sides of the kettle body 42, i.e. the front gas inlet 12 and the rear gas inlet 15 shown in Figure 1 The gas-phase fluorine-containing olefin monomers are added into the kettle body 42 through the front gas inlet 12 and the rear gas inlet 15, which is beneficial to the dispersion of the gas-phase fluorine-containing olefin monomers in the kettle body 42. The initiator inlet 45 is used for adding initiators into the kettle body 42. The discharge port 31 is used for discharging the materials reacted in the kettle body 42. When the pressure in the kettle body 42 rises to a pre-warning value, the safety relief port 13 is used for relieving the pressure of the kettle body 42.

[0025] The kettle body 42 includes a straight cylinder section and a head fixedly connected to the front and rear ends of the straight cylinder section. The length-diameter ratio of the kettle body 42 is 1.8, i.e. the ratio of the distance between the front and rear ends of the inner wall of the kettle body 42 to the inner diameter is 1.8.

[0026] The kettle body 42 is provided with an inner jacket 43 corresponding to the straight cylinder section and the front and rear heads, a front head jacket and a rear head jacket.

[0027] The inner wall of the straight cylinder section is provided with an inner jacket 43, the inner wall thickness of the inner jacket 43 is less than the wall thickness of the straight cylinder section, the inner jacket 43 is provided with a rib plate 46, and the rib plate 46 is fixedly connected with the inner wall of the inner jacket 43 and the wall surface of the straight cylinder section respectively. Based on this design, on the one hand, the inner wall of the inner jacket 43 can be directly in contact with the reaction system, and since the inner wall thickness of the inner jacket 43 is less than the wall thickness of the straight cylinder section, the thermal resistance between the cold / heat medium in the inner jacket 43 and the reaction system in the kettle body can be reduced, and the heat transfer coefficient can be improved; on the other hand, the inner wall of the inner jacket 43 can conduct the high pressure in the kettle body 42 to the wall surface of the straight cylinder section through the rib plate, so that the pressure resistance of the inner wall of the inner jacket 43 can be ensured. In the embodiment, the rib plate 46 forms a spiral-shaped passage in the inner jacket 43, and in some other embodiments, the rib plate 46 can also form a passage in the inner jacket 43 which is connected in multiple sections along the front-rear direction.

[0028] The straight cylinder section is provided with an inner jacket cooling water inlet 30, an inner jacket cooling water outlet 10, an inner jacket steam inlet 17 and an inner jacket condensed water outlet 32 which are in communication with the inner jacket 43. The inner jacket steam inlet 17 is used for inputting steam into the inner jacket 43, and the inner jacket condensed water outlet 32 is used for outputting condensed water in the inner jacket 43. The steam inputted into the inner jacket 43 exchanges heat with the material in the kettle body 42, so that the required temperature for the reaction in the kettle body 42 can be provided. The inner jacket cooling water inlet 30 is used for inputting cooling water into the inner jacket 43, and the inner jacket cooling water outlet 10 is used for outputting the cooling water in the inner jacket 43. After the reaction is completed, the cooling water inputted into the inner jacket 43 exchanges heat with the material in the kettle body 42, so that the material can be rapidly cooled, and the production efficiency can be improved. If the steam and the cooling water share one pipe for inputting and outputting, problems such as steam impact of the pipe, water hammer when switching the medium and the like are prone to occur. Therefore, in the embodiment, the inner jacket cooling water inlet 30, the inner jacket cooling water outlet 10, the inner jacket steam inlet 17 and the inner jacket condensed water outlet 32 are arranged on the straight cylinder section, so that the steam and the cooling water can be inputted and outputted through separate pipes.

[0029] The head located at the front end of the straight cylinder section is provided with a front head jacket cooling water inlet 33 and a front head jacket cooling water outlet 9 which are in communication with the front head jacket; and the head located at the rear end of the straight cylinder section is provided with a rear head jacket cooling water inlet 29 and a rear head jacket cooling water outlet 18 which are in communication with the rear head jacket.

[0030] The shaft sealing device comprises a front end mechanical sealing device 4, a rear end mechanical sealing device 23, a front end balance liquid tank 6 and a rear end balance liquid tank 21, the front end balance liquid tank 6 is connected with the front end mechanical sealing device 4 through a pipeline, and the rear end balance liquid tank 21 is connected with the rear end mechanical sealing device 23 through a pipeline. The mechanical sealing device is prior art, and can be seen from the mechanical sealing system disclosed in CN218177926U, which is provided with a material blocking mechanical sealing structure, the mechanical sealing device supports the stirring shaft 44 and forms a seal between the sealing head and the stirring shaft 44. The sealing head is provided with a flange 47, the front end mechanical sealing device 4 and the rear end mechanical sealing device 23 are respectively inserted into the two sealing heads through the inner hole of the flange 47, so that the material flow dead zone between the kettle body 42 and the front end mechanical sealing device 4 and the rear end mechanical sealing device 23 is avoided, and accumulation is caused to cause demulsification plasticization.

[0031] The stirring mechanism comprises a stirring shaft 44, a motor, a speed reducer 1, a spiral ribbon stirrer 14 and an anchor stirrer.

[0032] The stirring shaft 44 is rotatably supported on the kettle body 42 through the front end mechanical sealing device 4 and the rear end mechanical sealing device 23, and the two ends of the stirring shaft 44 respectively extend out of the kettle body 42. The front end of the kettle body 42 is provided with a rack 2, the motor and the speed reducer 1 are installed on the rack 2, and the motor transmits power to the stirring shaft 44 through the speed reducer 1 and a shaft coupling 3 in sequence.

[0033] The spiral ribbon stirrer 14 is located in the middle of the kettle body 42, the spiral ribbon stirrer 14 comprises four spiral belts arranged in staggered positions, and the spiral belts are fixedly installed on the stirring shaft 44 through stirring fixed rods 16 at the two ends of the spiral belts. The ratio of the diameter of the spiral ribbon stirrer 14 to the inner diameter of the kettle body 42 is 0.95, the ratio of the width of the spiral belt to the inner diameter of the kettle body 42 is 0.05, and the helix angle of the spiral belt is 180°. The spiral ribbon stirrer 14 can increase the radial flow in the kettle body 42 and generate large back pressure, so that more fluorine-containing olefins in the gas phase are brought into the liquid phase, and at the same time, the spiral ribbon stirrer 14 can also generate axial flow, thereby improving the mixing effect between the liquid phases.

[0034] The anchor stirrer is fixedly installed on the stirring shaft 44, and each of the anchor stirrers is provided with a group at the two sealing heads, that is Figure 1The front end anchor stirrer 8 and the rear end anchor stirrer 19 are shown. The anchor stirrer comprises 4 arc-shaped flat paddle blades connected in sequence, the outer edge shape of a part of the arc-shaped flat paddle blades is consistent with the shape of the inner wall surface of the corresponding side head, and the distance between the part of the arc-shaped flat paddle blades and the inner wall surface of the corresponding side head is 30 mm. The ratio of the diameter of the anchor stirrer to the inner diameter of the kettle body 42 is 0.85, and the ratio of the width of the arc-shaped flat paddle blade to the inner diameter of the kettle body 42 is 0.05. The anchor stirrer quickly stirs the liquid pushed by the ribbon stirrer 14 to the head, avoiding heat accumulation of the material at the head, especially the emulsion plasticization caused by the interaction of heat accumulation and mechanical shearing at the shaft seal device.

[0035] The anchor stirrer and the ribbon stirrer 14 work together to make the gas phase fluorine-containing olefins in the kettle body 42 more easily enter the liquid phase space, the stirring and mixing effect in the liquid phase is good, there is no flow dead zone in the kettle body 42, and local heat accumulation causing emulsion breaking is avoided.

[0036] Before the first reaction, pure water is added to the front end balance liquid tank 6 and the rear end balance liquid tank 21, so that there is no liquid compression space in the front end mechanical seal device 4, the rear end mechanical seal device 23, the front end balance liquid tank 6 and the rear end balance liquid tank 21. After the oxygen content in the kettle body 42 is qualified, pure water, dispersing agent and the like are added to the kettle body 42 from the front side gas inlet 12 and the rear side gas inlet 15, the gas phase fluorine-containing olefin monomer is introduced into the kettle body 42 through the front side gas inlet 12 and the rear side gas inlet 15 under a certain pressure, and the ribbon stirrer 14 and the anchor stirrer rotate to stir the pure water in the kettle body 42, so that the gas phase fluorine-containing olefin monomer is dissolved into the pure water. The steam enters the inner jacket 43 through the inner jacket steam inlet 17, and the steam condensate is discharged through the inner jacket condensate outlet 32. The steam exchanges heat with the material, so that the reaction system is heated. After the target pressure and temperature are reached, the initiator is added to the kettle body 42 from the initiator inlet 45, and the fluororesin emulsion polymerization reaction starts. The ribbon stirrer 14 provides a large back pressure to bring the gas phase fluorine-containing olefins into the liquid phase, improves the gas-liquid mixing effect, and the front end anchor stirrer 8 and the rear end anchor stirrer 19 quickly stir the liquid pushed by the ribbon stirrer 14 to the head, avoiding heat accumulation of the material at the head. After the reaction is completed, the emulsion in the kettle body 42 is discharged from the discharge port 31, and then the discharge port 31 is closed.

[0037] In the embodiment, the stirring shaft 44 is rotatably supported on the kettle body 42 through the front end mechanical seal device 4 and the rear end mechanical seal device 23, thereby effectively preventing the rotation of the stirring shaft from being hindered by the PVDF self-polymerization at the shaft seal device; and the two ends of the stirring shaft 44 respectively extend out of the kettle body 42, so that the two ends of the stirring shaft 44 are subjected to uniform force load, preventing the front end mechanical seal device 4 or the rear end mechanical seal device 23 from being damaged due to the uneven force load in the kettle body 42.

[0038] Example 2

[0039] Figure 2 Embodiment 2 of the utility model is shown.

[0040] The horizontal kettle for fluororesin reaction provided by the embodiment is used for producing fluororesin by emulsion method, and is used for emulsion polymerization reaction in aqueous solution under the action of initiators, molecular material regulators, dispersants and other additives, with fluorine-containing olefin monomers as main reaction monomers (such as vinylidene fluoride, tetrafluoroethylene, tetrafluoroethylene and hexafluoropropylene mixture, etc.), and different reaction pressures and reaction temperatures according to different fluororesins, the reaction pressure ranges from 1.0 to 5.0 Mpa, and the reaction temperature ranges from 50 to 150 DEG C, and a stable water emulsion is obtained after the reaction is completed.

[0041] As Figure 2 shown, a horizontal kettle for fluororesin reaction, comprising a kettle body 42, a stirring mechanism, a shaft sealing device, a shaft sealing balance system and a flushing system.

[0042] The kettle body 42 is provided with a gas inlet, an initiator inlet 45, a discharge port 31 and a safety relief port 13. The gas inlet is used for adding pure water, dispersants, gas phase fluorine-containing olefin monomers and other materials into the kettle body 42, in the embodiment, the kettle body 42 is provided with two gas inlets, the two gas inlets are respectively located on the front and rear sides of the kettle body 42, i.e. Figure 2 The front gas inlet 12 and the rear gas inlet 15 shown in the front side of the kettle body 42, the gas phase fluorine-containing olefin monomers are added into the kettle body 42 through the front gas inlet 12 and the rear gas inlet 15, which is beneficial to the dispersion of the gas phase fluorine-containing olefin monomers in the kettle body 42. The initiator inlet 45 is used for adding initiators into the kettle body 42; the discharge port 31 is used for discharging the materials reacted in the kettle body 42; when the pressure in the kettle body 42 rises to a warning value, the safety relief port 13 is used for relieving the pressure of the kettle body 42.

[0043] The kettle body 42 comprises a straight cylinder section and a head fixedly connected to the front and rear ends of the straight cylinder section. The length-diameter ratio of the kettle body 42 is 1.8, that is, the ratio of the distance between the front and rear ends of the inner wall of the kettle body 42 to the inner diameter is 1.8.

[0044] The kettle body 42 is provided with an inner jacket 43 corresponding to the straight cylinder section and the front and rear heads, a front head jacket and a rear head jacket.

[0045] The inner wall of the straight cylinder section is provided with an inner jacket 43, the inner wall thickness of the inner jacket 43 is less than the wall thickness of the straight cylinder section, the inner jacket 43 is provided with a rib plate 46, and the rib plate 46 is fixedly connected with the inner wall of the inner jacket 43 and the wall surface of the straight cylinder section respectively. Based on this design, on the one hand, the inner wall of the inner jacket 43 can be directly in contact with the reaction system, and since the inner wall thickness of the inner jacket 43 is less than the wall thickness of the straight cylinder section, the thermal resistance between the cold / heat medium in the inner jacket 43 and the reaction system in the kettle body can be reduced, and the heat transfer coefficient can be improved; on the other hand, the inner wall of the inner jacket 43 can conduct the high pressure in the kettle body 42 to the wall surface of the straight cylinder section through the rib plate, so that the pressure resistance of the inner wall of the inner jacket 43 can be ensured. In the embodiment, the rib plate 46 forms a spiral-shaped passage in the inner jacket 43, and in some other embodiments, the rib plate 46 can also form a passage in the inner jacket 43 which is connected in multiple sections along the front-rear direction.

[0046] The straight cylinder section is provided with an inner jacket cooling water inlet 30, an inner jacket cooling water outlet 10, an inner jacket steam inlet 17 and an inner jacket condensed water outlet 32 which are in communication with the inner jacket 43. The inner jacket steam inlet 17 is used for inputting steam into the inner jacket 43, and the inner jacket condensed water outlet 32 is used for outputting condensed water in the inner jacket 43. The steam inputted into the inner jacket 43 exchanges heat with the material in the kettle body 42, so that the required temperature for the reaction in the kettle body 42 can be provided. The inner jacket cooling water inlet 30 is used for inputting cooling water into the inner jacket 43, and the inner jacket cooling water outlet 10 is used for outputting the cooling water in the inner jacket 43. After the reaction is completed, the cooling water inputted into the inner jacket 43 exchanges heat with the material in the kettle body 42, so that the material can be rapidly cooled, and the production efficiency can be improved. If the steam and the cooling water share one pipe for inputting and outputting, problems such as steam impact of the pipe, water hammer when switching the medium and the like are prone to occur. Therefore, in the embodiment, the inner jacket cooling water inlet 30, the inner jacket cooling water outlet 10, the inner jacket steam inlet 17 and the inner jacket condensed water outlet 32 are arranged on the straight cylinder section, so that the steam and the cooling water can be inputted and outputted through separate pipes.

[0047] The head located at the front end of the straight cylinder section is provided with a front head jacket cooling water inlet 33 and a front head jacket cooling water outlet 9 which are in communication with the front head jacket; and the head located at the rear end of the straight cylinder section is provided with a rear head jacket cooling water inlet 29 and a rear head jacket cooling water outlet 18 which are in communication with the rear head jacket.

[0048] The shaft sealing device comprises a front end mechanical sealing device 4, a rear end mechanical sealing device 23, a front end balance liquid tank 6 and a rear end balance liquid tank 21, the front end balance liquid tank 6 is connected with the front end mechanical sealing device 4 through a pipeline, and the rear end balance liquid tank 21 is connected with the rear end mechanical sealing device 23 through a pipeline. The mechanical sealing device is prior art, and can be seen from the mechanical sealing system disclosed in CN218177926U, which is provided with a material blocking mechanical sealing structure, the mechanical sealing device supports the stirring shaft 44 and forms a seal between the sealing head and the stirring shaft 44. The sealing head is provided with a flange 47, the front end mechanical sealing device 4 and the rear end mechanical sealing device 23 are respectively inserted into the two sealing heads through the inner hole of the flange 47, so that the material flow dead zone between the kettle body 42 and the front end mechanical sealing device 4 and the rear end mechanical sealing device 23 is avoided, and accumulation is caused to cause demulsification plasticization.

[0049] The stirring mechanism comprises a stirring shaft 44, a motor, a speed reducer 1, a spiral ribbon stirrer 14 and an anchor stirrer.

[0050] The stirring shaft 44 is rotatably supported on the kettle body 42 through the front end mechanical sealing device 4 and the rear end mechanical sealing device 23, and the two ends of the stirring shaft 44 respectively extend out of the kettle body 42. The front end of the kettle body 42 is provided with a rack 2, the motor and the speed reducer 1 are installed on the rack 2, and the motor transmits power to the stirring shaft 44 through the speed reducer 1 and a shaft coupling 3 in sequence.

[0051] The spiral ribbon stirrer 14 is located in the middle of the kettle body 42, the spiral ribbon stirrer 14 comprises four spiral belts arranged in staggered positions, and the spiral belts are fixedly installed on the stirring shaft 44 through stirring fixed rods 16 at the two ends of the spiral belts. The ratio of the diameter of the spiral ribbon stirrer 14 to the inner diameter of the kettle body 42 is 0.95, the ratio of the width of the spiral belt to the inner diameter of the kettle body 42 is 0.05, and the helix angle of the spiral belt is 180°. The spiral ribbon stirrer 14 can increase the radial flow in the kettle body 42 and generate large back pressure, so that more fluorine-containing olefins in the gas phase are brought into the liquid phase, and at the same time, the spiral ribbon stirrer 14 can also generate axial flow, thereby improving the mixing effect between the liquid phases.

[0052] The anchor stirrer is fixedly installed on the stirring shaft 44, and each of the anchor stirrers is provided with a group at the two sealing heads, that is Figure 2The front end anchor stirrer 8 and the rear end anchor stirrer 19 are shown. The anchor stirrer comprises 4 arc-shaped flat paddle blades connected in sequence, the outer edge shape of a part of the arc-shaped flat paddle blades is consistent with the shape of the inner wall surface of the corresponding side head, and the distance between the part of the arc-shaped flat paddle blades and the inner wall surface of the corresponding side head is 30mm. The ratio of the diameter of the anchor stirrer to the inner diameter of the kettle body 42 is 0.85, and the ratio of the width of the arc-shaped flat paddle blade to the inner diameter of the kettle body 42 is 0.05. The anchor stirrer quickly stirs the liquid pushed by the ribbon stirrer 14 to the head, avoiding heat accumulation of the material at the head, especially the emulsion plasticization at the shaft seal device caused by the interaction of heat accumulation and mechanical shearing at the shaft seal device.

[0053] The anchor stirrer and the ribbon stirrer 14 cooperate to make the gas phase fluorine-containing olefin in the kettle body 42 more easily enter the liquid phase space, the stirring and mixing effect in the liquid phase is good, there is no flow dead zone in the kettle body 42, and local heat accumulation causing emulsion breaking is avoided.

[0054] The shaft seal balance system comprises a mechanical seal liquid water tank 34, a mechanical seal water pump 35, an in-kettle pressure sensor 11, a front end balance liquid tank pressure sensor 7, a front end balance liquid tank water inlet electromagnetic valve 37, a front end balance liquid tank pressure relief valve 5, a rear end balance liquid tank pressure sensor 20, a rear end balance liquid tank water inlet electromagnetic valve 36, a rear end balance liquid tank pressure relief valve 22 and a control system.

[0055] The mechanical seal liquid in the mechanical seal liquid water tank 34 is pure water, and the resistivity is greater than or equal to 10 megaohms.

[0056] The mechanical seal liquid water tank 34, the mechanical seal water pump 35, the front end balance liquid tank water inlet electromagnetic valve 37, the front end balance liquid tank 6 and the front end balance liquid tank pressure relief valve 5 are connected in sequence by pipelines and constitute a circulating loop. The mechanical seal liquid in the mechanical seal liquid water tank 34 is driven by the mechanical seal water pump 35, is pumped into the front end balance liquid tank 6 through the front end balance liquid tank water inlet electromagnetic valve 37 and the front end balance liquid tank water inlet pipe 40 in sequence, and returns to the mechanical seal liquid water tank 34 through the front end balance liquid tank pressure relief valve 5 and the front end balance liquid tank pressure relief pipe 38 in sequence.

[0057] The mechanical seal liquid water tank 34, the mechanical seal water pump 35, the rear end balance liquid tank water inlet electromagnetic valve 36, the rear end balance liquid tank 21 and the rear end balance liquid tank pressure relief valve 22 are connected in sequence by pipelines and constitute a circulating loop. The mechanical seal liquid in the mechanical seal liquid water tank 34 is driven by the mechanical seal water pump 35, is pumped into the rear end balance liquid tank 21 through the rear end balance liquid tank water inlet electromagnetic valve 36 and the rear end balance liquid tank water inlet pipe 39 in sequence, and returns to the mechanical seal liquid water tank 34 through the rear end balance liquid tank pressure relief valve 22 and the rear end balance liquid tank pressure relief pipe 27 in sequence.

[0058] The machine seal water pump 35, the in-kettle pressure sensor 11, the front-end balance liquid tank pressure sensor 7, the front-end balance liquid tank water inlet electromagnetic valve 37, the front-end balance liquid tank pressure relief valve 5, the rear-end balance liquid tank pressure sensor 20, the rear-end balance liquid tank water inlet electromagnetic valve 36 and the rear-end balance liquid tank pressure relief valve 22 are connected with a control system, which is a DCS (Distributed Control System) in the embodiment. The in-kettle pressure sensor 11 is used to acquire the pressure in the kettle body 42, the front-end balance liquid tank pressure sensor 7 is used to detect the pressure in the front-end balance liquid tank 6, and the rear-end balance liquid tank pressure sensor 20 is used to detect the pressure in the rear-end balance liquid tank 21. The DCS controls the machine seal water pump 35, the front-end balance liquid tank water inlet electromagnetic valve 37 and the front-end balance liquid tank pressure relief valve 5 according to the difference between the pressure in the kettle body 42 and the pressure in the front-end balance liquid tank 6, and controls the machine seal water pump 35, the rear-end balance liquid tank water inlet electromagnetic valve 36 and the rear-end balance liquid tank pressure relief valve 22 according to the difference between the pressure in the kettle body 42 and the pressure in the rear-end balance liquid tank 21, so as to realize automatic pressurization or pressure relief of the front-end mechanical seal device 4 and the rear-end balance liquid tank 21, thereby ensuring the sealing performance of the front-end mechanical seal device 4 and the rear-end mechanical seal device 23.

[0059] The flushing system comprises a flushing water tank 28, a flushing water pump 26, a rotary joint 24 and flushing nozzles 41. The stirring shaft 44 is a hollow structure, and a plurality of flushing nozzles 41 are arranged on the stirring shaft 44 at intervals along the axial direction of the stirring shaft 44. The flushing nozzles 41 change in direction according to the position, and the high-pressure washing water sprayed by the flushing nozzles 41 can cover the entire area in the kettle body 42. The flushing nozzles 41 are in communication with the inner cavity of the stirring shaft 44, the rotary joint 24 is connected to one end of the stirring shaft 44 and in communication with the inner cavity of the stirring shaft 44, and the flushing water tank 28, the flushing water pump 26 and the rotary joint 24 are sequentially connected by pipelines. When cleaning of the kettle is required, the flushing water pump 26 pumps the flushing water in the flushing water tank 28 into the stirring shaft 44 through the flushing water pipe 25, the rotary joint 24 and the flushing nozzles 41 in sequence, and the flushing water is sprayed out of the flushing nozzles 41 to flush the inner wall of the kettle body 42 and the powder attached to the stirring mechanism.

[0060] Before the first reaction, the oxygen content in the kettle body 42 is treated to reach the qualified level. Pure water, dispersing agent and the like are added into the kettle body 42 through the front gas inlet 12 and the rear gas inlet 15. The gaseous fluorine-containing olefin monomer is introduced into the kettle body 42 through the front gas inlet 12 and the rear gas inlet 15 under a certain pressure. The helical ribbon stirrer 14 and the anchor stirrer rotate to stir the pure water in the kettle body 42, so that the gaseous fluorine-containing olefin monomer is dissolved into the pure water. The steam enters the inner jacket 43 through the inner jacket steam inlet 17, and the steam condensate is discharged through the inner jacket condensate outlet 32. The steam exchanges heat with the material, so that the reaction system is heated. After the target pressure and temperature are reached, the initiator is added into the kettle body 42 through the initiator inlet 45, and the fluororesin emulsion polymerization reaction starts. The helical ribbon stirrer 14 provides a large back pressure to bring the gaseous fluorine-containing olefin into the liquid phase, so as to improve the gas-liquid mixing effect. The front anchor stirrer 8 and the rear anchor stirrer 19 push the helical ribbon stirrer 14 to the liquid at the head end, so as to quickly stir the liquid, and avoid heat accumulation of the material at the head end.

[0061] The DCS real-time monitors the pressure values obtained by the front balance liquid tank pressure sensor 7, the rear balance liquid tank pressure sensor 20 and the kettle pressure sensor 11. When the pressure in the kettle body 42 is higher than the pressure in the front balance liquid tank 6, the front balance liquid tank 6 needs to be pressurized, otherwise the PVDF emulsion will enter the front mechanical seal device 4, and will be broken and self-polymerized to form plastic material under the friction of the shaft and the front mechanical seal device 4, and will hinder the rotation of the stirring shaft 44. The specific pressurization process is as follows: the DCS controls the opening of the mechanical seal water pump 35 and the front balance liquid tank water inlet electromagnetic valve 37, the mechanical seal liquid in the mechanical seal liquid tank 34 is pumped into the front balance liquid tank 6, and the process is stopped until the pressure in the front balance liquid tank 6 is higher than the pressure in the kettle body 42 by 0.05-0.4 MPa. When the pressure in the front balance liquid tank 6 is higher than the pressure in the kettle body 42 by 0.4 MPa or more, the front balance liquid tank 6 needs to be depressurized, otherwise the front mechanical seal device 4 will be easily damaged under the pressure higher than 0.4 MPa for a long time. The specific depressurization process is as follows: the DCS controls the opening of the front balance liquid tank pressure relief valve 5, the mechanical seal liquid in the front balance liquid tank 6 flows back to the mechanical seal liquid tank 34, and the process is stopped until the pressure in the front balance liquid tank 6 is higher than the pressure in the kettle body 42 by 0.05-0.4 MPa. The shaft seal balance system performs the same operation on the pressure balance of the rear balance liquid tank 21. Under various working conditions such as pressure increasing stage, variable pressure reaction and system abnormality, the shaft seal balance system can keep the pressure of the front balance liquid tank 6 or the pressure of the rear balance liquid tank 21 higher than the pressure in the kettle body 42 by 0.05-0.4 MPa, so as to ensure the sealing performance of the shaft seal device.

[0062] After the reaction is completed, the emulsion in the kettle body 42 is discharged from the discharge port 31. Then the discharge port 31 is closed, the flushing water pump 26 is opened for cleaning the kettle, and the cleaning water is discharged from the discharge port 31 after the flushing is completed.

[0063] Example 3

[0064] The difference between this example and Example 2 is that the ribbon agitator 14 in this example comprises 6 helical ribbons arranged in staggered manner, the ratio of the diameter of the ribbon agitator 14 to the inner diameter of the kettle body 42 is 0.98, the ratio of the width of the helical ribbons to the inner diameter of the kettle body 42 is 0.1, and the helix angle of the helical ribbons is 90°. The anchor agitator comprises 4 arc flat paddle blades connected in sequence, the outer edge shape of a part of the arc flat paddle blades is consistent with the shape of the inner wall surface of the corresponding side head, and the distance between the part of the arc flat paddle blades and the inner wall surface of the corresponding side head is 50 mm. The ratio of the diameter of the anchor agitator to the inner diameter of the kettle body 42 is 0.5, and the ratio of the width of the arc flat paddle blades to the inner diameter of the kettle body 42 is 0.08.

[0065] Example 4

[0066] The difference between this example and Example 2 is that the length-diameter ratio of the kettle body 42 in this example is 2.

Claims

1. A horizontal tank for fluororesin reaction, characterized by comprising: It includes kettle body (42), stirring mechanism and shaft sealing device; the kettle body (42) includes straight cylinder section and the head fixedly connected to the front and rear ends of straight cylinder section; the shaft sealing device includes front end mechanical seal device (4), rear end mechanical seal device (23), front end balance liquid tank (6) and rear end balance liquid tank (21), the front end mechanical seal device (4) and rear end mechanical seal device (23) are installed on two the head is connected with front end mechanical seal device (4) by pipeline, rear end balance liquid tank (21) is connected with rear end mechanical seal device (23) by pipeline; the stirring mechanism includes stirring shaft (44), the stirring shaft (44) is rotatably supported on kettle body (42) by front end mechanical seal device (4) and rear end mechanical seal device (23), and the both ends of the stirring shaft (44) extend to the outside of kettle body (42) respectively.

2. The horizontal tank for fluororesin reaction according to claim 1, wherein It also includes shaft sealing balance system, the shaft sealing balance system includes machine seal liquid water tank (34), machine seal water pump (35), kettle pressure sensor (11), front end balance liquid tank pressure sensor (7), front end balance liquid tank water inlet solenoid valve (37), front end balance liquid tank pressure relief valve (5), rear end balance liquid tank pressure sensor (20), rear end balance liquid tank water inlet solenoid valve (36), rear end balance liquid tank pressure relief valve (22) and control system; The machine seal liquid water tank (34), machine seal water pump (35), front end balance liquid tank water inlet solenoid valve (37), front end balance liquid tank (6) and front end balance liquid tank pressure relief valve (5) are sequentially connected by pipeline and constitute a circulation loop, the machine seal liquid water tank (34), machine seal water pump (35), rear end balance liquid tank water inlet solenoid valve (36), rear end balance liquid tank (21) and rear end balance liquid tank pressure relief valve (22) are sequentially connected by pipeline and constitute a circulation loop; The machine seal water pump (35), kettle pressure sensor (11), front end balance liquid tank pressure sensor (7), front end balance liquid tank water inlet solenoid valve (37), front end balance liquid tank pressure relief valve (5), rear end balance liquid tank pressure sensor (20), rear end balance liquid tank water inlet solenoid valve (36) and rear end balance liquid tank pressure relief valve (22) are connected with control system; the kettle pressure sensor (11) is used to obtain the pressure in the kettle body (42), the front end balance liquid tank pressure sensor (7) is used to detect the pressure in the front end balance liquid tank (6), and the rear end balance liquid tank pressure sensor (20) is used to detect the pressure in the rear end balance liquid tank (21).

3. The horizontal tank for fluororesin reaction according to claim 1, wherein The stirring mechanism also includes screw belt stirrer (14) and anchor stirrer, the screw belt stirrer (14) and anchor stirrer are fixedly installed on the stirring shaft (44), the screw belt stirrer (14) is located in the middle of the kettle body (42), and two the anchor stirrer is located at the two ends of the kettle body (42).

4. The horizontal tank for fluororesin reaction according to claim 3, wherein The screw ribbon agitator (14) comprises 4-6 helical ribbons arranged in staggered manner, the ratio of the diameter of the screw ribbon agitator (14) to the inner diameter of the kettle body (42) is 0.95-0.98, the ratio of the width of the helical ribbon to the inner diameter of the kettle body (42) is 0.05-0.1, and the helical ribbon has a helical pitch angle of 90-180 degrees.

5. The horizontal tank for fluororesin reaction according to claim 3, wherein The anchor agitator comprises 2-4 arc-shaped flat paddle blades connected in sequence, the outer edge shape of at least a part of the arc-shaped flat paddle blades is consistent with the shape of the inner wall surface of the corresponding side head, and the distance between the part of the arc-shaped flat paddle blades and the inner wall surface of the corresponding side head is 30-50 mm; the ratio of the diameter of the anchor agitator to the inner diameter of the kettle body (42) is 0.5-0.85, and the ratio of the width of the arc-shaped flat paddle blade to the inner diameter of the kettle body (42) is 0.05-0.

08.

6. The horizontal tank for fluororesin reaction according to any one of claims 1 to 5, characterized by The kettle body (42) has a length-diameter ratio of 1.8-2.

7. The horizontal tank for fluororesin reaction according to any one of claims 1 to 5, characterized by The flushing system comprises a flushing water tank (28), a flushing water pump (26), a rotary joint (24) and a flushing nozzle (41), the stirring shaft (44) is a hollow structure, a plurality of flushing nozzles (41) are arranged on the stirring shaft (44) in the axial direction, the flushing nozzles (41) are in communication with the inner cavity of the stirring shaft (44), the rotary joint (24) is connected to one end of the stirring shaft (44) and is in communication with the inner cavity of the stirring shaft (44), and the flushing water tank (28), the flushing water pump (26) and the rotary joint (24) are sequentially connected by pipelines.

8. The horizontal tank for fluororesin reaction according to any one of claims 1 to 5, characterized by The inner wall of the straight cylinder section is provided with an inner jacket (43), the inner wall thickness of the inner jacket (43) is smaller than the wall thickness of the straight cylinder section, and the inner jacket (43) is provided with a rib plate (46) fixedly connected with the inner wall of the inner jacket (43) and the wall surface of the straight cylinder section.

9. The horizontal tank for fluororesin reaction according to claim 8, wherein The straight cylinder section is provided with an inner jacket cooling water inlet (30), an inner jacket cooling water outlet (10), an inner jacket steam inlet (17) and an inner jacket condensate outlet (32) in communication with the inner jacket (43).

10. The horizontal tank for fluororesin reaction according to any one of claims 1 to 5, characterized by The kettle body (42) is provided with two air inlets, and the two air inlets are respectively located on the front and rear sides of the kettle body (42).

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