Polycarbonate precipitation device

Abstract

The utility model provides a polycarbonate precipitation device which comprises a precipitation unit and a circulating unit, the precipitation reaction unit comprises a precipitation reaction kettle, a precipitation tank and a washing tank, and the precipitation reaction kettle is sequentially connected with a precipitation pipe and the washing tank through guide pipes; the circulating unit comprises a flash tank, a first solvent storage tank, a second solvent storage tank and a third solvent storage tank, the top of the settling tank is connected with the top of the first solvent storage tank, the bottom of the first solvent storage tank is connected with the flash tank through a ramming pump, a heater is arranged between the first solvent storage tank and the flash tank, the top of the flash tank is connected with the second solvent storage tank, and the third solvent storage tank is connected with the third solvent storage tank. A condenser is arranged between the flash tank and the solvent storage tank II, the bottom of the flash tank is connected with a solvent storage tank III, and the solvent storage tank III is connected with the precipitation reaction kettle through a poor solvent pipeline by virtue of a circulating pump. According to the utility model, the solid separation process of polycarbonate from the polycarbonate solution can be efficiently realized, meanwhile, the solvent can be recycled, and the green production is realized.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of chemical production, and particularly relates to a polycarbonate precipitation device. BACKGROUND

[0002] Polycarbonate is a kind of high molecular polymer containing carbonate group in the main chain, and according to the development history of polycarbonate synthesis technology, solution phosgene method, interfacial polycondensation method, melt ester exchange method and other synthesis technologies have been produced in succession.Taking the photochemical method as an example: raw material dihydroxy diphenyl propane (bisphenol a) is reacted with phosgene in inert organic solvent, and polycarbonate product in solution form is obtained.

[0003] In various polycarbonate production and manufacturing processes, the reaction is carried out in a good solvent for polycarbonate, and the obtained polycarbonate solution can be obtained from the solution in various ways:

[0004] (1) extrusion, volatilization of solvent in high concentration polycarbonate solution, and extrusion of polycarbonate without solvent;

[0005] (2) drying, evaporation of solvent from solution, so that polycarbonate exists in a certain solid form;

[0006] (3) precipitation, crystallization and precipitation of polycarbonate by changing the solvent composition, and solid material is obtained by filtration.

[0007] On a large commercial scale, the most suitable for large-scale production is the precipitation scheme, i.e. precipitation of polycarbonate from solution (using polycarbonate poor solvent as precipitant), and then removing by filtration or other separation means. But these methods have some disadvantages: first, due to the unrecycled polycarbonate in the filtrate after filtration, the corresponding yield loss is about 15%. Second, it is difficult to completely separate the solvent from the non-solvent, and the residual polycarbonate in the filtrate precipitates and accumulates in the solvent recovery step, thereby hindering or even preventing the effective heat transfer required for complete separation, and in severe cases, even causing pipe blockage. In addition, a large amount of polycarbonate good solvent and poor solvent is used in this method, and a large amount of heat is required to recover the solvent, so the solvent recovery stage requires high energy consumption and continuous device maintenance cost. INVENTION CONTENTS

[0008] The technical problem to be solved by the utility model is to provide a polycarbonate precipitation device, which can realize the solid separation process of polycarbonate from polycarbonate solution in large quantities and high efficiency, and the device can realize the recycling of solvent and realize green production.

[0009] To solve the above technical problems, the embodiment of the utility model provides a kind of polycarbonate precipitation device, including precipitation reaction unit and circulation unit, the precipitation reaction unit includes precipitation reaction kettle, sedimentation tank and washing tank, the precipitation reaction kettle is connected with sedimentation pipe and washing tank in turn by conduit, and the precipitation reaction kettle is connected with the sedimentation tank by conduit.

[0010] Wherein, the inside of precipitation reaction kettle is provided with sleeve, the outer wall of sleeve is provided with baffle, sleeve is fixedly connected with the inner wall of precipitation reaction kettle by baffle, the stirring shaft of stirrer is inserted into sleeve by passing through precipitation reaction kettle, the outer wall of precipitation reaction kettle is provided with discharge port, the top of precipitation reaction kettle is provided with polycarbonate solution inlet pipeline extending into sleeve, the bottom is provided with poor solvent pipeline extending into sleeve, and the poor solvent pipeline is connected with circulation unit.

[0011] The circulation unit includes flash tank, solvent storage tank one, solvent storage tank two and solvent storage tank three, the top of sedimentation tank is connected with the top of solvent storage tank one, the bottom of solvent storage tank one is connected with flash tank by material pumping, and heater is arranged between solvent storage tank one and flash tank, the top of flash tank is connected with solvent storage tank two, condenser is arranged between flash tank and solvent storage tank two, the bottom of flash tank is connected with solvent storage tank three, and solvent storage tank three is connected with precipitation reaction kettle by poor solvent pipeline through circulating pump, and is communicated with washing tank through pipeline.

[0012] Wherein, the baffle is provided with four, and gap is left between the baffles.

[0013] Wherein, the outer wall of precipitation reaction kettle is provided with interlayer, heating oil is arranged in the interlayer, and heating oil inlet and outlet are further arranged on the top of precipitation reaction kettle.

[0014] Wherein, the height of discharge port is higher than the height of sleeve arranged in precipitation reaction kettle, and is higher than the height of baffle arranged in precipitation reaction kettle.

[0015] Wherein, the bottom end of precipitation reaction kettle is further provided with kettle bottom discharge port.

[0016] Wherein, the bottom of washing tank is communicated with drying treatment equipment, and the drying treatment equipment is provided with collecting equipment.

[0017] The beneficial effects of the above technical solution of the utility model are as follows:

[0018] The precipitation reaction unit can efficiently realize the solid separation process of polycarbonate from polycarbonate solution in large quantities, and the circulation unit can realize the recycling use of solvent, realizing green production. ACCURACY OF DRAWINGS

[0019] Figure 1 It is a structural schematic view of the present application.

[0020] Figure 2 It is a structural schematic view of the precipitation reactor in the present application.

[0021] Mark explanation:

[0022] 1, precipitation reactor; 2, sedimentation tank; 3, washing tank; 4, drying treatment equipment; 5, flash tank; 6, solvent storage tank one; 7, solvent storage tank two; 8, solvent storage tank three; 9, material pump; 10, heater; 11, condenser; 12, circulating pump; 101, sleeve; 102, partition; 103, stirrer; 104, discharge port; 105, polycarbonate solution inlet pipeline; 106, poor solvent pipeline; 107, heating oil inlet and outlet; 108, kettle bottom discharge port. Specific implementation

[0023] In order to make the technical problems, technical schemes and advantages to be solved by the present application more clear, the following will be described in detail in combination with the drawings and specific embodiments.

[0024] As shown in Figure 1 , Figure 2 , the embodiment of the present application provides a polycarbonate precipitation device, which comprises a precipitation reaction unit and a circulating unit, the precipitation reaction unit comprises a precipitation reactor 1, a sedimentation tank 2 and a washing tank 3, the precipitation reactor 1 is connected with the sedimentation tank 2 and the washing tank 3 in sequence through a conduit. The bottom of the washing tank is communicated with a drying treatment equipment 4, and the drying treatment equipment 4 is provided with a collecting equipment.

[0025] Among them, the inside of the precipitation reactor 1 is provided with a sleeve 101, the outer wall of the sleeve 101 is provided with a partition 102, and the sleeve 101 is fixedly connected with the inner wall of the precipitation reactor 1 through the partition 102. In the embodiment, the partition 102 is provided with four, and a gap is left between the partitions. When the polycarbonate solution reacts and the slurry enters the space between the sleeve and the precipitation reactor, it will move along the flow direction, but due to the gap, the back mixing of the slurry can be greatly reduced, so that the particle size distribution of the product polycarbonate particles is more concentrated.

[0026] The stirring shaft of the stirrer 103 penetrates the precipitation reactor 1 and extends into the sleeve 101. The outer wall of the precipitation reactor 1 is provided with a discharge port 104. Further, the height of the discharge port 104 is higher than the height of the sleeve 101 arranged in the precipitation reactor 1, and higher than the height of the partition 102 arranged in the precipitation reactor 1.

[0027] The top of the precipitation reactor 1 is provided with a polycarbonate solution inlet pipe 105 extending into the sleeve 101, and the bottom of the precipitation reactor 1 is provided with a poor solvent pipe 106 extending into the sleeve 101 and connected with a circulating unit.

[0028] In the embodiment, the precipitation reactor 120L has an inner radius of 25 cm, the stirring paddle has a radius of 12 cm, the stirring paddle blade is a paddle type, the distance between the paddle blade and the bottom of the reactor is 35 cm, the distance between the paddle blade and the horizontal height of the discharge port is 25 cm, the sleeve has a length of 55 cm and a radius of 15 cm, the lower end of the sleeve is 10 cm away from the bottom of the reactor, and the upper end of the sleeve is 5 cm higher than the horizontal line of the discharge port. The sleeve is connected with the inner wall of the reactor through four partitions, each partition has a length of 45 cm and a width of 10 cm, and the upper end of each partition is lower than the horizontal height of the discharge port.

[0029] The circulating unit comprises a flash tank 5, a solvent storage tank one 6, a solvent storage tank two 7, and a solvent storage tank three 8. The top of the precipitation tank 2 is connected with the top of the solvent storage tank one 6, the bottom of the solvent storage tank one 6 is connected with the flash tank 5 through a discharging pump 9, a heater 10 is arranged between the solvent storage tank one 6 and the flash tank 5, the top of the flash tank 5 is connected with the solvent storage tank two 7, a condenser 11 is arranged between the flash tank 5 and the solvent storage tank two 7, the bottom of the flash tank 5 is connected with the solvent storage tank three 8, the solvent storage tank three 8 is connected with the precipitation reactor through a poor solvent pipe 106 and a circulating pump 12, and is connected with the washing tank 3 through a pipe.

[0030] The working principle of the utility model is as follows:

[0031] The precipitation process is as follows: when the device is running, polycarbonate solution is added into the sleeve 101 from the polycarbonate solution inlet pipe 105, and poor solvent is injected into the sleeve on the side of the stirring paddle from the poor solvent pipe 106. After the polycarbonate solution and the poor solvent are mixed by the stirrer 103, polycarbonate particles begin to precipitate and settle. At this time, due to the difference in liquid level between the inside and outside of the sleeve 101, the polycarbonate slurry moves along the outer wall of the sleeve 101 to the inner wall space of the precipitation reactor 1, and is discharged from the discharge port 104 on the wall of the precipitation reactor 1. The discharged polycarbonate slurry enters the precipitation tank 2 for solid-liquid separation.

[0032] At this time, a simple communication device is formed on both sides of the sleeve, and the movement of the polycarbonate slurry in the kettle is driven by the pressure difference caused by the height difference of the liquid surface. Moreover, the space between the sleeve 101 and the inner wall of the precipitation kettle 1 is divided into a long channel (gap) by the partition plate. After the polycarbonate slurry in the kettle enters the channel, it moves along the flow direction, greatly reducing the back mixing of the slurry, and the particle size distribution of the polycarbonate particles is more concentrated. By controlling the addition amount of polycarbonate solution and the corresponding proportion of poor solvent flow, the balance and trade-off between production efficiency and product quality can be achieved.

[0033] After the polycarbonate slurry enters the precipitation tank 2, the solids gradually settle to the bottom, and the liquid is introduced into the solvent storage tank 6 from the upper opening of the precipitation tank 2. When the solid-liquid interface approaches the upper opening of the precipitation tank 2, the slurry mainly composed of solids is introduced into the washing tank 3 from the tank bottom passage of the precipitation tank 2, and poor solvent is added to the washing tank 3. In the washing tank 3, the solids are further precipitated, and then the solids and liquids are separated by standing, the upper liquid is pumped out to the solvent storage tank 6, and the solids are sent to the drying treatment equipment 4 for drying to obtain solid polycarbonate.

[0034] The circulating process is as follows: the liquid in the solvent storage tank 6 is pumped out at a certain rate by the material pumping pump 9, the liquid material is heated by the heater 10 to rise, and then enters the flash tank 5. In the flash tank 5, the good solvent is vaporized and recovered to the solvent storage tank 2 through condensation, and the recovery rate is controlled by adjusting the reflux ratio of the condenser 11 to make the recovery rate of the good solvent equal to the addition amount of the good solvent in the polycarbonate solution; the remaining solvent enters the solvent storage tank 3 through the lower opening of the flash tank 5, and the solvent in the solvent storage tank 3 can be recycled by the circulating pump 12 and used again as poor solvent in the precipitation kettle 1 and the washing tank 3.

[0035] Next, the technical scheme of the utility model will be further described in combination with specific embodiments.

[0036] Example one,

[0037] Using the above polycarbonate precipitation device, 10% polycarbonate dichloromethane solution is introduced into the sleeve from the upper opening of the precipitation kettle through the polycarbonate solution inlet pipeline at a pumping rate of 9.7 kg / min; at the same time, the poor solvent is continuously pumped from the solvent storage tank 3 through the kettle bottom inlet at a pumping rate of 29.1 kg / min. The two streams meet and mix near the stirring paddle. The poor solution contains 44% dichloromethane and 56% cyclohexane, and the kettle temperature is 25°C. The stirring paddle mixes and generates polycarbonate solid precipitation in the inner side of the sleeve, and the obtained slurry flows along the material flow direction, passes through the channel (gap) composed of the sleeve-kettle wall-partition plate, and reaches the discharge port of the precipitation kettle.

[0038] The slurry is transferred from the outlet of the precipitation reactor to the sedimentation tank through a pipe, and the solid particles in the slurry gradually sink to the bottom of the tank, and the solution is discharged from the outlet of the sedimentation tank to the solvent storage tank 1; when the upper edge of the solid part reaches the outlet of the tank body, the solid is discharged from the lower outlet of the tank body to the washing tank.

[0039] After the solid slurry is added to the washing tank, the poor solvent is pumped from the solvent storage tank 3 into the washing tank, and the bottom stirring is started to slowly stir the slurry, so as to promote the dissolution of the solvent contained in the solid particles. After maintaining the stirring for 20 min, the stirring is stopped for 10 min, and the supernatant is pumped into the solvent storage tank 1 using a pump, and the remaining solid is transported to the tubular dryer for drying, to obtain 58.2 kg / h of dry solid.

[0040] The solution in the solvent storage tank 1 is pumped out at a rate of 39 kg / min to the heat exchanger, and the solution is heated to 80℃ in the heat exchanger and then enters the flash tank. The gas at the upper outlet of the flash tank is condensed to obtain dichloromethane liquid, and the reflux ratio is adjusted so that the flow rate of dichloromethane is 8.7 kg / min, and the dichloromethane liquid enters the solvent storage tank 2 for recycling. The liquid obtained from the lower outlet of the flash tank is loaded into the solvent storage tank 3 to supply the precipitation reactor and the washing tank for recycling, and the dichloromethane / cyclohexane ratio is unchanged, and the rate is 29.1 kg / min. The recovered liquid contains a small amount of polycarbonate.

[0041] Example two,

[0042] Using the above-mentioned polycarbonate precipitation device, 30% concentration polycarbonate / dichloromethane is continuously added to the 120L capacity precipitation reactor at a rate of 8.4 kg / min, and the poor solvent composed of 43% dichloromethane and 57% cyclohexane is added at a rate of 16.8 kg / min. The subsequent operation and control standard are the same as those of example one, the cyclohexane proportion in the filtrate of the solvent storage tank 1 is 42%, and is pumped into the heat exchanger and the flash tank at a rate of 22.7 kg / min, and is separated into 5.9 kg / min of dichloromethane into the solvent storage tank 2 for recycling, and 16.8 kg / min of the same proportion of poor solvent into the solvent storage tank 3 for recycling. When the device is stably operated, 151.2 kg / h of solid is produced in the dryer.

[0043] In summary, the polycarbonate solid separation process can be realized from the polycarbonate solution in large quantities and high efficiency, and the recycling unit can realize the recycling use of the solvent, and green production is realized.

[0044] The above-mentioned is the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be regarded as the protection scope of the present application.

Claims

1. A polycarbonate precipitation apparatus comprising a precipitation reaction unit and a circulation unit, characterized by, The precipitation reaction unit comprises a precipitation reaction kettle, a precipitation tank and a washing tank, and the precipitation reaction kettle is connected with the precipitation tank and the washing tank in sequence through a pipeline; The inside of the precipitation reaction kettle is provided with a sleeve, the outer wall of the sleeve is provided with a partition plate, the sleeve is fixedly connected with the inner wall of the precipitation reaction kettle through the partition plate, a stirrer is arranged on the precipitation reaction kettle in a matched mode, the stirring shaft of the stirrer penetrates the precipitation reaction kettle and extends into the sleeve, a discharge port is formed in the outer wall of the precipitation reaction kettle, a poor solvent pipeline is arranged in the sleeve and extends to the bottom of the precipitation reaction kettle, and the poor solvent pipeline is connected with the circulating unit; The circulating unit comprises a flash tank, a solvent storage tank one, a solvent storage tank two and a solvent storage tank three, the top of the precipitation tank is connected with the top of the solvent storage tank one, the bottom of the solvent storage tank one is connected with the flash tank through a material discharging pump, a heater is arranged between the solvent storage tank one and the flash tank, the top of the flash tank is connected with the solvent storage tank two, a condenser is arranged between the flash tank and the solvent storage tank two, the bottom of the flash tank is connected with the solvent storage tank three, the solvent storage tank three is connected with the precipitation reaction kettle through a poor solvent pipeline by a circulating pump, and the solvent storage tank three is connected with the washing tank through a pipeline.

2. The polycarbonate precipitation apparatus of claim 1, wherein, The partition plate is provided with four gaps.

3. The polycarbonate precipitation apparatus of claim 1, wherein, The outer wall of the precipitation reaction kettle is provided with a sandwich layer, the sandwich layer is provided with heating oil, and the top of the precipitation reaction kettle is further provided with a heating oil inlet and outlet.

4. The polycarbonate precipitation apparatus of claim 1, wherein, The height of the discharge port is higher than the height of the sleeve arranged in the precipitation reaction kettle.

5. The polycarbonate precipitation apparatus of claim 1, wherein, The bottom end of the precipitation reaction kettle is further provided with a kettle bottom discharge port.

6. The polycarbonate precipitation apparatus of claim 1, wherein, The bottom of the washing tank is connected with a drying treatment device, and the drying treatment device is provided with a collecting device.

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