CN112321754B - Polymer solution devolatilization device and method - Google Patents
Polymer solution devolatilization device and method Download PDFInfo
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- CN112321754B CN112321754B CN202010926056.5A CN202010926056A CN112321754B CN 112321754 B CN112321754 B CN 112321754B CN 202010926056 A CN202010926056 A CN 202010926056A CN 112321754 B CN112321754 B CN 112321754B
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- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F6/00—Post-polymerisation treatments
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Abstract
The invention discloses a polymer solution devolatilization device and a polymer solution devolatilization method. The device comprises a polymer solution feeding pipeline, a preheater, a first devolatilization unit, a heater, a second devolatilization unit, a polymer delivery pump and the like, wherein the polymer solution feeding pipeline is connected with an inlet of the preheater, an outlet of the preheater is connected with the first devolatilization unit, a liquid phase outlet at the bottom of the first devolatilization unit is connected with the heater, an outlet of the heater is connected with an inlet of the second devolatilization unit, and the bottom of the second devolatilization unit is connected with the polymer delivery pump. The polymer solution enters a preheater, and the heated polymer solution enters a first devolatilization unit to evaporate part of volatile matters; the polymer solution with the removed part of volatile matters flows into a heater under the combined action of pressure difference and gravity, and enters a second devolatilization unit after being reheated by the heater, so that the residual part of volatile matters in the polymer are removed. The devolatilization device provided by the invention is ingenious in design, and the use of pipelines and moving equipment is effectively reduced.
Description
Technical Field
The invention relates to a polymer solution devolatilization device and a polymer solution devolatilization method.
Background
The production of polymers often involves removal of volatiles. First, monomers and solvents need to be recovered from the polymer solution for reuse; secondly, the polymer itself needs to remove volatile components such as monomers, solvents, byproducts and the like to meet the performance requirements of the polymer; finally, the undepleted volatiles accumulate readily during polymer handling and storage, and when exposed to air, they are highly likely to form an explosive atmosphere, which can be hazardous to personnel and the environment.
Devolatilization of polymer solutions has its particular difficulties. Although the relative volatility of the solvent and the polymer is very high, the devolatilization stage enters a diffusion devolatilization stage from a flash devolatilization stage along with the removal of the solvent, the viscosity of the polymer is exponentially increased, and a small amount of volatile matters are dissolved and coated in the polymer and are difficult to completely remove.
CN1662561A teaches a method for removing volatile components from a polymer composition, wherein a polymer solution is continuously preheated by a multi-tube heat exchanger and then fed into a first volatilizer, a polymer melt below the first volatilizer is fed again into the heat exchanger by a melt pump and heated and then fed into a second volatilizer, and a polymer melt obtained from the lower part of the second volatilizer is sent out by the melt pump. According to the method for removing the volatile components of the polymer, a melt pump and a heat exchanger are additionally arranged between devolatilizers, the conveying system is complex, the polymer pipeline is long, the retention time is long, and blockage is easily caused. In addition, the additional dynamic seal also increases the amount of air leakage, which adversely affects the polymer quality.
CN102858415A teaches a devolatilization apparatus and method by passing a polymer solution (melt) continuously through a plate heater having a heating channel designed or operated such that the pressure of the melt (solution) is greater than the bubble point pressure in the polymer melt passing through a first region of greater size and a second region of lesser size, and ultimately a polymer melt having less than 2000ppm of volatile components at the bottom of the volatilization chamber. Although the devolatilization limit of the polymer solution is not given in this patent, the first stage devolatilization is limited to thermodynamic equilibrium, and it is impossible to remove all volatiles in the solution at once at a low polymer concentration. Therefore, at a low concentration of the polymer solution, the effective volatile removal effect cannot be maintained.
CN109646975A teaches a polymer devolatilization apparatus which integrates the functions of feed distribution, heating, strip and falling film devolatilization and material collection, and the polymer is finally transported to the product or post-treatment part under the action of a material pushing device, which integrates dynamic and static devolatilization, and can perform efficient devolatilization of the polymer at a proper temperature. However, in a polymer system with a high viscosity, for example, when the viscosity of the polymer exceeds 1000000cP, the umbrella-shaped falling film distributor in the device is difficult to uniformly distribute the polymer, and the high-viscosity polymer is easy to block and hang on the wall. Meanwhile, relatively complex inner components inevitably form dead zones in the device, so that polymer is coked and blocked, and long-period stable operation of the device is difficult to realize.
US3583672 describes a falling film devolatilizer with two flash tanks and a preheater, the preheater is arranged and connected above the first flash tank, the second flash tank is positioned below the first flash tank, the two flash tanks are connected through a pipeline and are provided with liquid level regulating valves, the liquid level of the first flash tank can be regulated so as to keep a stable pressure difference between the two flash tanks, and the two flash tanks are provided with heating jackets. The efficiency of the devolatilization of a particular polymer solution is not given in this patent, but the temperature of the polymer solution is significantly reduced if the amount of flash evaporation is large during the devolatilization of the polymer, and therefore, if the solvent in the low concentration polymer solution is to be removed, as described in US3668161, US8153757B2, multiple stages of heating are often required.
Aiming at the characteristics of devolatilization of a polymer system and the problems of the existing devolatilization device, an efficient devolatilization device and an efficient devolatilization method are needed to be found, so that an operation device and a conveying system which are simplified as much as possible are used, the volatile matters in a low-concentration polymer solution are effectively removed, meanwhile, the devolatilization device of the devolatilization device can be kept to stably operate for a long period, and the purposes of stable polymer product quality and less operation of personnel are achieved.
Disclosure of Invention
In order to remove volatile components (including unreacted monomers or raw materials, solvents for dissolving and reducing polymer viscosity, byproducts of polymerization reaction and other low molecular impurities) in a polymer solution, particularly a low-concentration polymer solution, the invention provides a devolatilization device and a devolatilization method.
According to a first aspect of the present invention, there is provided an apparatus for devolatilizing a polymer solution, which comprises a polymer solution feed line, a preheater, a flash tank (first devolatilization unit), a heater, an evaporation tank (second devolatilization unit), a polymer transfer pump, and the like.
Wherein, polymer solution feed line connects the pre-heater entry, and the pre-heater export directly links the flash tank through the pipe connection flash tank or through the flange, and the liquid phase export of flash tank bottom passes through flange or welded connection heater, and the heater export is located the evaporating pot entry of flash tank below through flange or welded connection, and the polymer delivery pump is connected to the evaporating pot bottom.
Further, the preheater may be a shell-and-tube heat exchanger, a spiral plate heat exchanger, a heat exchanger with internals inside the tube, etc., and preferably, the preheater is a heat exchanger with internals.
Further, when the preheater is connected with the flash tank through a pipeline, a pressure reducing valve is arranged at the pipeline inlet of the flash tank, and the distance between the pressure reducing valve and the flash tank is as small as possible. The line inlet of the flash tank is preferably arranged in the upper half of the flash tank.
Further, the upper half part of the flash tank is provided with a gas phase outlet and a gas phase outlet pipeline connected with the gas phase outlet, the gas phase outlet is provided with a baffle, and the baffle can be in a circular shape, an oval shape, a polygonal shape and the like. The baffle is used for removing polymer liquid drops entrained in the gas phase, and a gas phase channel is reserved between the baffle and the gas phase outlet. For smooth gas discharge from the flash tank and for liquid droplet removal, a gas phase channel flow area and a gas phase outlet area ratio of the flash tank are required to be within a certain range. Preferably, the gas phase flow area between the baffle and the gas phase outlet is 0.1 to 50 times the gas phase outlet area, more preferably, the gas phase flow area between the baffle and the gas phase outlet is 1 to 30 times the gas phase outlet area, more preferably, the gas phase flow area between the baffle and the gas phase outlet is 1.2 to 10 times the gas phase outlet area.
Preferably, the flash tank gas-phase outlet line is required to be step-high, i.e. sloped, upwardly oriented, with a slope of not less than 1 °, preferably, a slope of not less than 3 °, not more than 90 °; and a control valve is arranged on the gas phase outlet pipeline and used for regulating and controlling the pressure in the flash tank.
The heater is connected between the flash tank and the evaporating tank through flanges or welding. The heater can be a common shell-and-tube heat exchanger or a shell-and-tube heat exchanger with an internal component, the selection of the heat exchanger depends on the viscosity of the polymer solution, when the viscosity is too high, the pressure difference between two sides of the heater can not provide the power required by the polymer solution passing through the heat exchanger with the internal component, and the common shell-and-tube heat exchanger is selected.
Preferably, the heating medium of the heater is one of steam, molten salt and heat transfer oil, and more preferably, the heating medium of the heater is heat transfer oil.
Further, the inner diameter of the heat exchange tube of the heater is 6-50mm, preferably 6-20mm, and more preferably 8-15 mm.
Preferably, the outlet at the bottom of the heat exchange tube of the heater is provided with a throttling facility. The throttling facility can be a solid with a smooth surface or a flat plate with holes, and only needs to bear the pressure difference between the flash tank and the evaporation tank. As an example, the throttling means may be a smooth surfaced ball, cylinder, or the like, or a flat plate with a strip-shaped hole, a ring-shaped hole, a polygonal hole, a star-shaped hole, a gourd-shaped hole, a cross-stripe. Preferably, each heat exchange tube is provided with the same throttling device, such as a flat annular hole, so that the flow pressure drop of each heat exchange tube is the same, and the flow rate of each heat exchange tube is the same. The throttling means may be connected to the outlet of the heat exchange tube in any one of various ways, such as by screwing, welding, flange connection, etc.
The throttling facility is arranged at the bottom of the heat exchange tube of the heater and is used for: firstly, materials in the heat exchange tube of the heater are throttled, so that the polymer solution is uniformly distributed in the heat exchange tube; secondly, prevent that polymer solution flash distillation in the heat exchange tube, erode the heat exchange tube, in addition, the polymer flash distillation can cause the mobility variation in the heat exchange tube in advance, blocks up the heat exchange tube.
Further, a gas phase outlet arranged at the top of the evaporation tank is connected with a vacuum device through a pipeline. The lower part of the evaporation tank is connected with a polymer delivery pump through a pipeline or is directly connected with the polymer delivery pump. Preferably, the lower part of the evaporation tank is directly connected with a polymer conveying pump. The polymer delivery pump may be in the form of a pump well known in the art, such as a gear pump.
Preferably, the flash tank and the evaporation tank are heated by an external jacket, and the heating medium can be one of steam, molten salt and heat conducting oil. More preferably, the jacket heating medium is a heat transfer oil.
The devolatilization devices of the present invention may be connected in series to increase devolatilization efficiency, or may be connected in parallel to increase the production capacity of the device.
According to a second aspect of the present invention, there is provided a method of devolatilizing a polymer solution, the method comprising the steps of:
(1) conveying the polymer solution into a preheater through a polymer solution feeding pipeline, and feeding the heated polymer solution into a flash tank to evaporate part of volatile matters;
(2) the polymer solution with the removed part of volatile matters flows into a heater under the combined action of pressure difference and gravity, and enters an evaporation tank after being heated again by the heater, so that the residual part of volatile matters in the polymer are removed.
In the method of the present invention, the polymer may be polycarbonate, polysulfone, nylon, polyolefin, polyester, polystyrene, polyurethane, polyacrylate, polymethyl methacrylate, styrene-acrylonitrile copolymer, or may be an olefin copolymer, a combination thereof, or a combination thereof. The volatile components in the polymer solution are mainly unreacted monomers, by-products and solvents, and preferably the mass ratio of the volatile components in the polymer solution is 10% to 95%, more preferably 30% to 85%.
In the process of the present invention, the polymer solution in step (1) may be delivered by a natural pressure difference or by a pump, depending on the production process of the polymer, the pressure drop of the polymer solution through the piping and the preheater, and the operating pressure of the flash tank.
In the method, the operating pressure of the flash tank in the step (1) can be accurately controlled by the opening degree of a control valve on a gas phase pipeline. The operating pressure of the flash tank is 1-15 barA, preferably 3-12 barA.
In the method, the operation temperature of the polymer solution side in the preheater in the step (1) can be accurately controlled by controlling the temperature of the medium at the hot side (when the medium at the hot side is heat conduction oil or molten salt) or the flow rate of the medium at the hot side (when the medium at the hot side is steam), and the operation temperature of the polymer solution side is preferably 100-350 ℃, and more preferably 200-260 ℃.
In addition, in order to reduce the temperature of the polymer solution at the heating wall of the preheater as much as possible and to prevent the polymer solution from being degraded by excessive thermal degradation at the heating wall, it is required that the difference between the temperature of the heat medium and the operating temperature of the polymer solution side is not more than 20 ℃ and preferably not more than 10 ℃.
In the method, when the preheater is connected with the flash tank through a pipeline, in order to prevent the polymer solution from flashing in the preheater in advance, so that the polymer is scaled on the wall of the heat exchange pipe to reduce the heating capacity of the preheater, a pressure reduction valve is required to be added before the pipeline enters the flash tank, and the solution flashing is generated in the flash tank. Preferably, the pressure reducing valve is at a minimum distance from the flash tank.
In the inventive method, in order to prevent the polymer melt from being carried by the gas phase solvent/monomer to the gas phase line in the flash tank to clog the gas phase line and the valve, the flash tank gas phase line is required to be stepped up, i.e. with a certain slope, sloping upwards, the slope being not less than 1 °, preferably, the slope being not less than 3 °, not more than 90 °.
In the method of the present invention, in order to prevent the solvent from being vaporized in advance in the heater, the polymer solution side operating temperature of the heater in the step (2) is not higher than the polymer solution side operating temperature of the preheater in the step (1), and the temperature difference may be in the range of 5 ℃ to 110 ℃.
In the method of the present invention, in order to continuously and stably feed the polymer from the flash tank to the evaporation tank, the pressure drop of the heater in the step (2) is not greater than the pressure difference between the flash tank and the evaporation tank.
In the method of the present invention, in order to remove the volatile components as much as possible, the evaporation tank in the step (2) should be operated under vacuum. The operating pressure is 5mBarA to 1BarA, preferably 5mBarA to 100 mBarA. The operating pressure can be controlled by adjusting a control valve of a gas phase pipeline of the evaporating pot or adjusting a frequency converter of the vacuum unit.
According to different requirements on the content of volatile components in the devolatilized polymer and the treatment capacity of the polymer solution, multistage devolatilization can be carried out in a series connection mode, combined devolatilization can be carried out in a parallel connection mode, and the devolatilization can be carried out in series connection and parallel connection.
The invention has the positive effects that:
(1) in the process of devolatilizing the polymer solution, other additional moving equipment is not used except for conveying moving equipment, so that the devolatilizing energy consumption is low, the operation is convenient, and meanwhile, the long-period stable operation is facilitated.
(2) The equipment integration level is high, and transfer line is few, has reduced the resistance consumption in the transportation process, has also reduced the possibility of jam simultaneously.
(3) A two-stage heating mode, namely a preheater and a heater, is adopted, and the flash evaporation is immediately heated, so that volatile matters in the polymer solution with low concentration can be removed.
(4) The shear is small, and the method is very suitable for removing volatile matters in the shear sensitive polymer solution.
(5) The operation flexibility is large and the adaptability is wide. By adjusting the operating temperature and pressure, volatiles can be removed from different polymer products in various concentration ranges, especially in low concentration polymer solutions.
Drawings
FIG. 1 is a schematic view of a devolatilization apparatus for a polymerization solution according to the present invention.
In fig. 1: 1. the system comprises a polymer solution feeding pipeline, a preheater 2, a heat medium inlet pipeline 3, a heat medium outlet pipeline 4, a flash tank 5, a baffle 6, a flash tank gas phase pipeline 7, an evaporation tank gas phase pipeline 8, an evaporation tank 9, a throttling device 10, a heater (heat exchange pipe) 11, a polymer conveying pump 12 and a polymer conveying pipeline 13.
Fig. 2 is a schematic view of the baffles of the flash tank gas line inlet of the present invention, wherein the upper row is a side view showing the baffles and the lower row is a front view.
FIG. 3 is a schematic view of a throttling facility of a heat exchange tube of the heater of the present invention.
Detailed Description
The present invention is described in detail by the following embodiments, but the embodiments are representative embodiments and do not limit the scope of the present invention.
As shown in FIG. 1, the present invention provides an apparatus for devolatilizing a polymer solution, which comprises a preheater 2, a flash tank 5, a heater 11, a flash tank 9, and a polymer transfer pump 12.
Wherein, polymer solution feed line 1 connects 2 material side entrances of preheater, 2 material side exports of preheater pass through line connection flash tank 5, sets up the relief valve on the pipeline near the flash tank. The inlet of the gas phase line of the flash tank is provided with a baffle 6. The lower part of the flash tank is connected with a heater 11, and the outlet of a heat exchange tube of the heater 11 is provided with a throttling facility 10. The polymer solution heated by the heater 11 enters the evaporation tank 9 to further remove volatile matters in the polymer, a gas phase pipeline at the upper part of the evaporation tank is connected with a vacuum device, a liquid phase outlet of the evaporation tank is connected with a polymer delivery pump 12, and the polymer after 13 devolatilization is sent out through a polymer delivery pipeline.
Fig. 2 is a schematic illustration of a flash tank gas baffle 6. The gas phase baffle shown in fig. 2(a) is a circular baffle, the gas phase baffle shown in fig. 2(b) is a square baffle, and the gas phase baffle shown in fig. 2(c) is an oval baffle.
Fig. 3 shows a throttling means 10 installed at the end of the heat exchange tube of the heater 11, fig. 3(a) shows a throttling means in the form of a strip, fig. 3(b) (c) shows throttling means distributed in the form of circular holes and pentagonal holes, and fig. 3(d) (e) shows throttling means with a plurality of pentagonal and quadrangular holes.
The volatile content of the polymer was determined by gas chromatography.
Example 1
The devolatilization apparatus of this embodiment is as shown in fig. 1, where the circular baffle in fig. 2c is adopted as the baffle, the gas phase flows into the gas phase outlet of the flash tank through the wall gap between the baffle and the flash tank, the flow area is 1.5 times the cross-sectional area of the gas phase outlet, the gradient of the gas phase outlet pipeline of the flash tank is 3 °, and the connection manner between the heater and the flash tank and the evaporation tank is flange connection. The heating medium in the heater is heat conducting oil, the diameter of a heat exchange tube of the heater is phi 19 multiplied by 2mm, and the inner diameter is 15 mm. The throttling means is a bar hole as shown in figure 3 a.
According to the flow shown in figure 1, an ethylene-octene copolymer polymer solution containing 15 wt% of solvent cyclohexane enters a preheater through a polymer solution feeding pipeline, is preheated to 230 ℃, enters a flash tank for flash evaporation after being decompressed by an adjusting valve, the operating temperature of the flash tank is 164.9 ℃, the operating pressure is 5BarA, the polymer solution containing 68.3 wt% of ethylene-octene copolymer is obtained at the bottom of the flash tank after flash evaporation, and enters an evaporation tank after being heated to 171 ℃ by a heater at the bottom of the flash tank, the operating temperature of the evaporation tank is 120 ℃, the operating pressure is 0.05BarA, and a polymer melt with the volatile matter of less than 4000ppm is obtained at the bottom of the evaporation tank. The devolatilization device is operated continuously for one month without obvious abnormality.
Example 2
The same devolatilization apparatus and flow path as in example 1 were employed, the arrangement of the baffle plate, heater and flash tank gas phase line was maintained, and the rectangular holes as shown in FIG. 3e were employed as the throttling means.
The method comprises the steps of enabling a polymer solution containing 70 wt% of polysulfone and a solvent to be chlorobenzene, enabling the chlorobenzene to enter a preheater through a polymer solution feeding pipeline, preheating to 220 ℃, enabling the chlorobenzene to enter a flash tank after being decompressed by an adjusting valve, enabling the polymer solution to be flashed in the flash tank, enabling the operating temperature of the flash tank to be 189.5 ℃ and the operating pressure to be 1BarA, enabling the polymer solution with the polysulfone content of 90.7% to be obtained at the bottom of the flash tank after being flashed, enabling the polymer solution to enter an evaporation tank after being heated to 194 ℃ through a heater at the bottom of the flash tank, enabling the operating temperature of the evaporation tank to be 176.7 ℃ and the operating pressure to be 5mBar, and obtaining a polymer melt with the volatile matter of less than 500ppm at the bottom of the evaporation tank. The device operates and devolatilizes stably over a one month operating cycle.
Example 3
The same devolatilization apparatus and flow scheme as in example 1 was used, with the only difference being that a rectangular vapor baffle as shown in FIG. 2b was used, with the vapor flow area between the baffle and the flash drum wall being 1.2 times the cross-sectional area of the vapor outlet.
The polymer solution containing 50 wt% of styrene-acrylonitrile (SAN) polymer, the balance of the solution consisting of 20 wt% of ethylbenzene, 22.5 wt% of styrene and 7.5 wt% of acrylonitrile, enters a preheater through a polymer solution feeding line, is preheated to 230 ℃, enters a flash tank after being decompressed by an adjusting valve for flash evaporation, the operating temperature of the flash tank is 185.6 ℃, the operating pressure is 2BarA, the polymer solution with the SAN content of 77.9% is obtained at the bottom of the flash tank after flash evaporation, the polymer solution is heated to 190 ℃ through a heater at the bottom of the flash tank and then enters an evaporation tank, the operating temperature of the evaporation tank is 157 ℃, the operating pressure is 5mBar, and a polymer melt with the volatile content of less than 520ppm is obtained at the bottom of the evaporation tank, wherein the acrylonitrile content is less than 15 ppm. The devolatilization device runs for more than one month, the devolatilization effect is stable, and no abnormal phenomenon is found.
Comparative example 1
The same devolatilization apparatus and flow scheme as in example 2 were employed, with the only difference being that a rectangular throttling device was installed at the upper portion of the heat exchange tube of the heater.
The method comprises the steps of enabling a polymer solution containing 70 wt% of polysulfone and a solvent to be chlorobenzene, enabling the chlorobenzene to enter a preheater through a polymer solution feeding pipeline, preheating to 220 ℃, enabling the chlorobenzene to enter a flash tank after being decompressed by an adjusting valve, enabling the polymer solution to be flashed in the flash tank, enabling the operating temperature of the flash tank to be 189.5 ℃ and the operating pressure to be 1BarA, enabling the polymer solution with the polysulfone content of 90.7% to be obtained at the bottom of the flash tank after being flashed, enabling the polymer solution to enter an evaporation tank after being heated to 191 ℃ through a heater at the bottom of the flash tank, enabling the operating temperature of the evaporation tank to be 174.1 ℃ and the operating pressure to be 5mBar, and obtaining a polymer melt with the volatile matter of about 900ppm at the bottom of the evaporation tank. After two weeks of continuous operation, the treatment capacity of the device is reduced, and the cleaning device is disassembled to find that the blockage phenomenon occurs in part of the heat exchange tubes of the heater.
Comparative example 2
The same devolatilization apparatus and procedure as in example 2 were used, the only difference being that no bottom throttling was provided.
The method comprises the steps of enabling a polymer solution containing 70 wt% of polysulfone and a solvent to be chlorobenzene, enabling the chlorobenzene to enter a preheater through a polymer solution feeding pipeline, preheating to 220 ℃, enabling the chlorobenzene to enter a flash tank after being decompressed by an adjusting valve, enabling the polymer solution to be flashed in the flash tank, enabling the operating temperature of the flash tank to be 189.5 ℃ and the operating pressure to be 1BarA, enabling the polymer solution with the polysulfone content of 90.7% to be obtained at the bottom of the flash tank after being flashed, enabling the polymer solution to enter an evaporation tank after being heated to 190 ℃ through a heater at the bottom of the flash tank, enabling the operating temperature of the evaporation tank to be 171.5 ℃ and the operating pressure to be 5mBar, and obtaining a polymer melt with the volatile matter of 8500ppm at the bottom of the evaporation tank. After the continuous operation for 54h, the treatment capacity of the device is greatly reduced, and the disassembly device finds that the heat exchange tube close to the shell side of the heater is seriously blocked.
Claims (13)
1. A polymer solution devolatilization device comprises a polymer solution feeding pipeline connected with an inlet of a preheater, the preheater, a first devolatilization unit, a heater and a second devolatilization unit, wherein the first devolatilization unit is a flash tank, and the second devolatilization unit is an evaporation tank;
the outlet of the preheater is connected with the first devolatilization unit through a pipeline or is directly connected with the first devolatilization unit through a flange, the liquid phase outlet at the bottom of the first devolatilization unit is connected with a heater through a flange or a welding joint, the outlet of the heater is connected with the inlet of a second devolatilization unit positioned below the first devolatilization unit through a flange or a welding joint, and the bottom of the second devolatilization unit is connected with a polymer delivery pump;
the heater is a shell-and-tube heat exchanger, the outlet at the bottom of the heat exchange tube of the heater is provided with a throttling facility, and the throttling facility is in a three-dimensional or perforated flat plate shape with a smooth surface and is selected from a small ball and a cylinder with a smooth surface or a flat plate with strip-shaped holes, annular holes, polygonal holes, star-shaped holes, gourd-shaped holes and cross stripes;
when the preheater is connected with the first devolatilization unit through a pipeline, a pressure reduction valve is arranged at the inlet of the pipeline of the first devolatilization unit; the pipeline inlet of the first devolatilization unit is arranged at the upper half part;
the upper half part of the first devolatilization unit is provided with a gas phase outlet and a gas phase outlet pipeline connected with the gas phase outlet, and the gas phase outlet is provided with a baffle plate; the gas phase flow area between the baffle and the gas phase outlet is 0.1 to 50 times of the area of the gas phase outlet; the gas-phase outlet pipeline is required to be high in pace, with the gradient of not less than 1 ° and not more than 90 °.
2. The apparatus of claim 1, wherein the gas phase flow area between the baffle and the gas phase outlet is from 1 to 30 times the gas phase outlet area;
the gas-phase outlet line slope is not less than 3 °.
3. The apparatus of claim 2, wherein the gas phase flow area between the baffle and the gas phase outlet is 1.2 to 10 times the area of the gas phase outlet.
4. An apparatus according to any one of claims 1 to 3 wherein the heater heat exchange tube has a tube internal diameter of from 6 to 50 mm.
5. The apparatus of claim 4 wherein the heater heat exchange tube has a tube inside diameter of 6 to 20 mm.
6. The apparatus of claim 5 wherein the heater heat exchange tube has an internal diameter of 8-15 mm.
7. A method of devolatilizing a polymer solution using the apparatus of any one of claims 1 to 6, comprising the steps of:
(1) the polymer solution enters a preheater, and the heated polymer solution enters a first devolatilization unit to evaporate part of volatile matters;
(2) the polymer solution with the removed part of volatile matters flows into a heater under the combined action of pressure difference and gravity, and enters a second devolatilization unit after being reheated by the heater, so that the residual part of volatile matters in the polymer are removed;
wherein the polymer solution side operating temperature of the heater in the step (2) is not higher than the polymer solution side operating temperature of the preheater in the step (1), the temperature difference is in the range of 5 ℃ to 110 ℃, and the pressure drop of the heater in the step (2) is not more than the pressure difference between the flash tank and the evaporation tank.
8. The method of claim 7, wherein the polymer solution is selected from polysulfone, nylon, polyolefin, polyester, polystyrene, polyurethane, polyacrylate, polymethyl methacrylate, styrene-acrylonitrile copolymer solution, or olefin copolymer solution, olefin copolymer composition solution, wherein the content of volatile is in the range of 10% to 95%.
9. The method of claim 8, wherein the polymer solution has a volatile content in the range of 30-85%.
10. The method according to claim 7 or 8, wherein in the step (1), the operating temperature of the polymer solution side in the preheater is 100 ℃ to 350 ℃;
the operating pressure of the first devolatilization unit is 1-15 barA.
11. The method according to claim 10, wherein in the step (1), the operating temperature of the polymer solution side in the preheater is 200 ℃ to 260 ℃;
the operating pressure of the first devolatilization unit is 3-12 barA.
12. The process according to any one of claims 7-9, characterized in that the second devolatilization unit operating pressure is between 5mbar and 1 BarA.
13. The method of claim 12, wherein the second devolatilization unit operating pressure is from 5 to 100mbar a.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010926056.5A CN112321754B (en) | 2020-09-07 | 2020-09-07 | Polymer solution devolatilization device and method |
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| CN114478849A (en) * | 2021-11-05 | 2022-05-13 | 广州创特技术有限公司 | Polymer material devolatilization device |
| CN117507182A (en) * | 2024-01-05 | 2024-02-06 | 常州瑞华化工工程技术股份有限公司 | Isothermal devolatilizer |
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| US3773740A (en) * | 1971-10-21 | 1973-11-20 | Union Carbide Corp | Devolatilization method |
| CN2209156Y (en) * | 1994-11-10 | 1995-10-04 | 中国石油化工总公司 | Apparatus for devolatilization of polymerized liquid |
| DE19835744A1 (en) * | 1998-08-07 | 2000-02-17 | Bayer Ag | Process for evaporating polymer solutions of thermoplastic polymers |
| FR2843966A1 (en) * | 2002-08-30 | 2004-03-05 | Bp Chem Int Ltd | METHOD AND APPARATUS FOR DEGASSING A POLYMER |
| JP3797987B2 (en) * | 2003-07-11 | 2006-07-19 | Ｊｓｒ株式会社 | Method for removing solvent from polymer solution and method for producing polymer |
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| CN202808662U (en) * | 2012-07-05 | 2013-03-20 | 中国石油集团东北炼化工程有限公司吉林设计院 | Device for improving quality of acrylonitrile-styrene copolymer product |
| CN109646975A (en) * | 2019-02-28 | 2019-04-19 | 上海宥壹化工科技有限公司 | A kind of polymer devolatilization apparatus |
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