CN114797715B - Emulsion polymerization reaction kettle - Google Patents
Emulsion polymerization reaction kettle Download PDFInfo
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- CN114797715B CN114797715B CN202110059892.2A CN202110059892A CN114797715B CN 114797715 B CN114797715 B CN 114797715B CN 202110059892 A CN202110059892 A CN 202110059892A CN 114797715 B CN114797715 B CN 114797715B
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- 238000007720 emulsion polymerization reaction Methods 0.000 title claims abstract description 25
- 239000000463 material Substances 0.000 claims abstract description 32
- 238000003756 stirring Methods 0.000 claims abstract description 32
- 239000007788 liquid Substances 0.000 claims abstract description 18
- 239000012530 fluid Substances 0.000 claims abstract description 13
- 230000037431 insertion Effects 0.000 claims 1
- 238000003780 insertion Methods 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 abstract description 124
- 239000002245 particle Substances 0.000 abstract description 24
- 239000003995 emulsifying agent Substances 0.000 abstract description 20
- 239000004816 latex Substances 0.000 abstract description 18
- 229920000126 latex Polymers 0.000 abstract description 18
- 239000005062 Polybutadiene Substances 0.000 abstract description 16
- 229920002857 polybutadiene Polymers 0.000 abstract description 16
- 238000000034 method Methods 0.000 abstract description 12
- 239000003507 refrigerant Substances 0.000 abstract description 11
- 238000010008 shearing Methods 0.000 abstract description 7
- 230000000694 effects Effects 0.000 abstract description 4
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 122
- 239000002994 raw material Substances 0.000 description 23
- 239000007789 gas Substances 0.000 description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 21
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 18
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 16
- 238000009826 distribution Methods 0.000 description 12
- 238000005070 sampling Methods 0.000 description 11
- 239000007864 aqueous solution Substances 0.000 description 10
- 239000000203 mixture Substances 0.000 description 9
- 238000006116 polymerization reaction Methods 0.000 description 9
- 230000008569 process Effects 0.000 description 9
- 238000004458 analytical method Methods 0.000 description 8
- 239000003999 initiator Substances 0.000 description 8
- 229910052757 nitrogen Inorganic materials 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 239000003112 inhibitor Substances 0.000 description 7
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 5
- 239000000839 emulsion Substances 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000002194 synthesizing effect Effects 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 2
- 239000012267 brine Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000012761 high-performance material Substances 0.000 description 2
- -1 polyethylene Polymers 0.000 description 2
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- 206010024769 Local reaction Diseases 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000010559 graft polymerization reaction Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 229920006027 ternary co-polymer Polymers 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/18—Stationary reactors having moving elements inside
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/0053—Details of the reactor
- B01J19/0066—Stirrers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F236/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
- C08F236/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
- C08F236/04—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
- C08F236/10—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated with vinyl-aromatic monomers
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Polymerisation Methods In General (AREA)
Abstract
The invention discloses an emulsion polymerization reaction kettle. The reaction kettle comprises a vertical cylinder, wherein the upper end enclosure of the cylinder is provided with a material inlet, a gas inlet and a gas outlet, the gas outlet is connected with a vacuum system, and the lower end enclosure is provided with a material outlet; the stirring shaft is connected with the cylinder through mechanical seal. The blade below the four-blade ring stirrer has large size, can increase the liquid discharge capacity of the blade, strengthen the axial flow effect in the reaction kettle, and has saw-tooth shape, so that the blade above the four-blade ring stirrer can increase the shearing capacity of the blade on fluid. The method is used for producing polybutadiene latex, the axial temperature difference is small, the particle size is reduced to 180-500nm, the consumption of the emulsifier in the oil phase is increased, and the consumption of the refrigerant is reduced.
Description
Technical Field
The invention belongs to the technical field of emulsion polymerization, relates to important equipment in an ABS resin synthesis process, and in particular relates to an emulsion polymerization reaction kettle for synthesizing polybutadiene latex and a production method of the polybutadiene latex.
Background
In recent years, with the requirements of light weight and high performance of products such as electronic appliances, household consumer products and automobiles, the demand of high-performance materials is increasing, wherein ABS resin is used as a high-performance material with excellent performance, and has the characteristics of strong hardness, good heat resistance, strong impact resistance, good light transmittance, easy processing and the like, and is also called as five general-purpose resin with polyethylene, polypropylene, polyvinyl chloride and polystyrene. The ABS resin is ternary copolymer of acrylonitrile, butadiene and styrene. Emulsion graft polymerization is the most commonly used and most mature process for synthesizing ABS resin. At present, the stirrer used in the emulsion polymerization process in the industrial production of ABS resin is usually a multi-layer stirrer in combination, the stirrer in the upper light liquid area of the reaction kettle is more biased to shear liquid, the stirrer in the lower heavy liquid area of the reaction kettle is more biased to promote the suspension uniformity of dispersed phase liquid drops in the kettle and enhance the heat exchange effect of a heat exchange element. However, in the production process of polybutadiene latex, the dispersed phase butadiene needs to be continuously supplemented along with the reaction, the liquid level in the reaction kettle is increased from 40% to 80% in the whole reaction process, so that in most of the time of the reaction process, the stirrer for shearing the liquid above the reaction kettle cannot be fully utilized, and finally the particle size and the particle size distribution of the product in the reaction kettle cannot meet the requirements of the next process.
Disclosure of Invention
The invention provides an emulsion polymerization reaction kettle. The method is used for producing polybutadiene latex, the axial temperature difference is not more than 1 ℃, the particle size of the product is reduced to 180-500nm, and the consumption of the emulsifier in the oil phase is increased. The consumption of the refrigerant is reduced.
The aim of the invention is realized by the following technical scheme:
an emulsion polymerization reaction kettle comprises a vertical cylinder body 1, wherein the upper end socket of the cylinder body 1 is provided with a material inlet 2, a gas inlet 4 and a gas outlet 5, the gas outlet 5 is connected with a vacuum system, and the lower end socket is provided with a material outlet 3; the stirring shaft is connected with the cylinder through mechanical seal, and one end of the stirring shaft is connected with the power device 8, and the other end of the stirring shaft is connected with the four-blade ring stirrer 7.
Further, the ratio of the diameter D of the stirrer to the diameter T of the cylinder ranges from 0.6 to 0.9 according to different values of the final viscosity of the system, and when the final viscosity of the system is less than 1000cp, D/T=0.6; when the final viscosity of the system is 1000-5000cp, D/T=0.6-0.8; when the final viscosity of the system is 5000-10000cp, d/t=0.8-0.9.
The ratio of the height H of the stirrer to the height H of the cylinder is determined according to the final liquid loading amount in the reaction kettle, and the value range is 0.6 to 0.9.
Further, the four-blade ring stirrer 7 is composed of four blades, the included angle between the adjacent blades is 90 degrees, the blades are respectively fixed on the upper hub 11 and the lower hub 12, the wide blades 15 fixed on the lower hub 12 gradually narrow from the blade root 16 to the blade end 17, the ratio α of the width W1 of the blade end 17 to the width W2 of the blade root 16 is between 0.3 and 0.5, and the influence of the α value on the average flow velocity of the fluid in the reaction kettle can be calculated by the following formula:
V ave ＝αV tip (1)
V ave : average flow rate of fluid in the reaction kettle;
alpha: the ratio of blade end to blade root width;
V tip : maximum linear velocity (m/s) of blade, V tip ＝NПD；
N: stirring speed, rev/s;
d: stirrer diameter, m.
At the wide blade end 17, there is a narrow blade 13 in the vertical direction connected thereto, and the other end of the narrow blade 13 is connected to the upper hub 11 by a fixing member 18.
Further, the maximum value of the width under the narrow blades 13 is 0.1 to 0.2 times the stirrer diameter D.
Further, the upper part of the narrow blade 13 is provided with a serration opening to enhance the shearing action of the stirrer on the fluid, and the width of the narrow blade is gradually narrowed from bottom to top, the ratio of the serration opening length L1 to the height h of the stirrer is between 0.4 and 0.8, and the number m of serration is between 3 and 25. The ratio of the serrated opening length L1 to the narrow blade length L2 is related to the ratio n of the light material liquid level height to the heavy material liquid level height in the reaction kettle, and can be calculated by adopting the following formula:
L1/L2＝n+0.2 (2)
the ratio of the narrow blade length L2 to the stirrer height h ranges between 0.8 and 0.95.
Under the condition that the rotating speed and the diameter of the stirrer are fixed, the number m of the saw teeth on the narrow blades is related to the requirement of a system on the shearing force gamma, and the following formula can be adopted for calculation:
m＝Kγ (3)
the K value is related to the stirring speed N and the stirrer diameter D, and can be calculated approximately using k=nd.
Further, the lower parts (without saw-tooth openings) of the wide blades 15 and the narrow blades 13 of the four-blade ring stirrer 7 are provided with circular through holes so as to avoid material aggregation and effectively reduce the blocking force of the stirrer in the rotating process so as to reduce stirring power consumption, the ratio of the diameter of the circular through holes to the diameter D of the stirrer is between 0.01 and 0.08, and the ratio of the area of the circular through holes to the area of the blades (the sum of the areas of the wide blades and the area of the narrow blades) is between 0.05 and 0.15.
Further, a companion tube jacket is arranged outside the cylinder body, and the cross section of the companion tube jacket can be of any geometric shape.
Further, a heat exchange tube bundle 10 is arranged in the cylinder 1, the polymerization reaction heat is withdrawn in time, the heat exchange tube bundle and the cylinder are radially provided with a certain included angle beta, the included angle is between 15 degrees and 45 degrees, and the cooling medium in the tube bundle can be low-temperature brine or liquid ammonia. In order to reduce the power consumption of the stirrer and increase the heat transfer capacity of the heat exchange tube bundle, the included angle between the heat exchange tube bundle and the reaction kettle is determined by the liquid flow pattern and the flow velocity formed by the stirrer, and the preferable relationship between the included angle beta and the flow velocity V of the fluid at the heat exchange tube bundle (the fluid velocity at the heat exchange tube closest to the kettle wall) is as follows:
β＝90V (4)
the application range beta=15 degrees to 45 degrees of the formula (4), if the calculated value exceeds or is lower than the boundary value, the boundary value is preferably used as the included angle; and the beta size can be further adjusted according to engineering design.
The number of the heat exchange tube bundles can be 4 to 8 groups according to the heat release amount of the polymerization reaction, and the heat exchange tube bundles are uniformly distributed in the reaction kettle, and the number of single tubes of each group of tube bundles is 3 or 6.
The applicable range of the material viscosity of the emulsion polymerization reaction kettle is 1 centipoise to 10000 centipoise; the applicable temperature ranges from 60 ℃ to 100 ℃; the applicable pressure ranges from 0 to 5MPa.
The method for synthesizing the polybutadiene latex by using the emulsion polymerization kettle comprises the following steps: adding 40-50 ℃ high-temperature desalted water into a reaction kettle from a material inlet of an upper end socket of a cylinder body, starting stirring, sequentially adding an emulsifier, butadiene, styrene and an initiator aqueous solution, reacting at 70-85 ℃ to prepare the polybutadiene latex, adding butadiene monomer/emulsifier according to the reaction condition, finishing the reaction after the solid content in the reaction kettle reaches a target value, cooling after the reaction is finished, and conveying the emulsion obtained by the reaction into a degassing tank under pressure by adopting nitrogen.
The beneficial effects of the invention are that
The emulsion polymerization reaction kettle has the advantages that the diameter of the stirrer is larger than that of the cylinder, the proportion is in the range of 0.6-0.9, the stirrer can effectively enhance the mixing effect of materials in the reaction kettle, and in addition, the butadiene monomer/emulsifier added in the reaction process can be uniformly mixed with the materials in the kettle in a shorter time. The large ratio of the height of the stirrer to the height of the reaction kettle can enable the reaction kettle to be applied to various load working conditions, and is particularly suitable for the operation condition that the effective liquid level in the kettle is increased from 40% to 80% in the polybutadiene latex production process.
The four-blade ring type stirrer has larger size of the wide blade connected with the lower hub, the large blade has larger liquid discharge amount, the axial flow of fluid in the reaction kettle is greatly enhanced, and the distribution of butadiene liquid drops in the reaction kettle is more uniform, so that the situation that local reaction is too fast is avoided, and compared with an emulsion polymerization kettle using a multi-layer paddle combination, the emulsion polymerization kettle using the four-blade ring type stirrer can reduce the particle size distribution of products from 50nm to 2000nm to 180nm to 500nm. In addition, the strong axial flow in the reaction kettle can effectively improve the heat transfer capability of the heat exchange tube bundle in the barrel and the jacket of the accompanying tube outside the barrel, compared with the traditional multi-layer paddle combination reaction kettle, the axial temperature difference in the reaction kettle is reduced from 5 ℃ to not more than 1 ℃ in the process of producing polybutadiene latex by using the emulsion polymerization kettle, and further, the strong axial flow in the reaction kettle greatly reduces the material skinning amount on the heat exchange tube bundle, so that the shutdown cleaning frequency of the reaction kettle is prolonged from three months to one year.
The serrated openings of the narrow blades of the four-blade ring stirrer effectively improve the shearing capability of the stirrer to materials in the reaction kettle, so that butadiene in the reaction raw material can be thoroughly dispersed into small liquid drops, the specific surface area of the liquid drops of the raw material is increased, and the consumption of the emulsifier in the oil phase is increased.
In the invention, the angle between the heat exchange tube bundle and the cylinder is 15-45 degrees, the arrangement mode of the heat exchange tube bundle can change the movement mode of fluid in the kettle, improve the movement speed and the turbulence degree of the fluid near the kettle wall, and improve the heat exchange effect of the heat exchange tube bundle, compared with the traditional multi-layer paddle combination reaction kettle, the emulsion polymerization kettle can reduce the consumption of the refrigerant by 30 percent.
Drawings
FIG. 1 is a schematic diagram showing the structure of an emulsion polymerization reactor in front view;
FIG. 2 is a schematic view showing the arrangement of heat exchange tube bundles in a reactor cylinder according to the present invention;
FIG. 3 is a schematic diagram of the front view of a four-bladed ring stirrer according to the present invention;
in the figure: the reaction kettle comprises a reaction kettle barrel body 1, a material inlet 2, a material outlet 3, a gas inlet 4, a gas outlet 5, a stirring shaft 6, a stirrer 7, a power device 8, a tube-type jacket 9, a heat exchange tube bundle 10, a stirrer upper hub 11, a stirrer lower hub 12, a narrow blade 13, a circular through hole 14, a wide blade 15, a wide blade root 16, a wide blade end 17 and a fixing device 18.
Detailed Description
The invention is further described below with reference to the drawings and examples.
Particle size distribution, particle size testing: netherlands Malvern Panalytical laser particle sizer, model: mastersizer 3000.
Viscosity test: shanghai normani viscometer, model: MVS3.
Example 1
The emulsion polymerization reaction kettle comprises a vertical barrel 1, wherein the upper end socket of the barrel 1 is provided with a material inlet 2, a gas inlet 4 and a gas outlet 5, the gas outlet 5 is connected with a vacuum system, and the lower end socket is provided with a material outlet 3; the stirring shaft is connected with the cylinder through mechanical seal, and one end of the stirring shaft is connected with the power device 8, and the other end of the stirring shaft is connected with the four-blade ring stirrer 7. The four-bladed ring stirrer 7 is composed of four blades, the included angle between every two adjacent blades is 90 degrees, the blades are respectively fixed on an upper hub 11 and a lower hub 12, and the wide blades 15 fixed on the lower hub 12 are gradually narrowed from the blade root 16 to the blade end 17. At the wide blade end 17, there is a narrow blade 13 in the vertical direction connected thereto, and the other end of the narrow blade 13 is connected to the upper hub 11 by a fixing member 18. The upper part of the narrow blades 13 is provided with serrated openings to enhance the shearing action of the stirrer on the fluid, and the width of the narrow blades gradually narrows from bottom to top.
The volume of the reaction kettle is 60m 3 The diameter T of the reactor was 3.7m, the height H of the cylinder was 6.2m, and the diameter D of the stirrer was 3.33m (D/t=0.9). The stirrer height H was 4.34m (H/h=0.7). The width of the blade end of the wide blade portion was 0.5m, and the blade root width was 1m (α=0.5). The length L2 of the narrow blade is 3.7m, the length L1 of the serrated opening is 3m (setting n=0.61, then L1/L2=0.81; L2/h=0.85), the number of serrations is 22 (obtained from laboratory experiments, butadiene latex with the particle size distribution of 200nm to 500nm and the median particle size D50 of 350nm is prepared, the required average shearing gamma in the reaction kettle is 13.2/s), the width of the uppermost part of the narrow blade is 0.25m, the width of the lowermost part of the narrow blade is 0.5m (the ratio of D is 0.15), and the width gradually decreases from bottom to top. The 8 groups of heat exchange tube bundles are uniformly distributed in the reaction kettle, each group of heat exchange tube bundles has 6 heat exchange tubes, and the radial included angle beta between the heat exchange tube bundles and the cylinder body is 30 degrees (the fluid speed at one heat exchange tube closest to the kettle wall is 0.3 m/s). Each blade is provided with 5 circular through holes with the diameter of 0.2m (the ratio of D to D is 0.06), and the circular through holes are positioned at the non-serrated opening parts of the wide blade and the narrow blade.
Stirring was started and the stirring speed N was set at 0.5rev/s.
Adding desalted water at 50 ℃ into the reaction kettle, starting stirring, vacuumizing from a gas outlet 5 by using a vacuum pump, introducing nitrogen from a gas inlet 4, and performing operation for replacing the air in the kettle for multiple times. Under vacuum condition, an aqueous emulsifier (25 wt% of sodium dodecyl benzene sulfonate aqueous solution, the same applies below), an initiator aqueous solution (10 wt% of ammonium persulfate aqueous solution, the same applies below), styrene and butadiene are mixed according to a ratio of 1:1:0.3:4, wherein the feeding amount of butadiene was 12000kg. Refrigerant (low-temperature brine at the temperature of minus 10 ℃ and the same applies below) is introduced into the heat exchange tube bundle while feeding, and the refrigerant introduction amount is 56000kg/h. During the reaction, sampling analysis is carried out, when the conversion rate reaches 25%, the butadiene is added as a raw material, and the ratio of the butadiene addition amount to the initial addition amount is 2:1, the butadiene as a raw material is added for the second time when the conversion rate is 50%, and the ratio of the butadiene addition amount to the initial addition amount is 1.5:1, butadiene is added as a raw material when the conversion rate is 75%, and the ratio of the butadiene addition amount to the initial addition amount is 1:1, adding a polymerization inhibitor when the conversion rate is 90%, and ending the reaction. The axial temperature difference in the reaction kettle is 0.8 ℃ in the reaction process. The whole reaction process is carried out for 30 hours at 70 ℃, sampling analysis is carried out on materials, the content of emulsifying agent in water phase in the materials is 0.001%, the particle size distribution of polybutadiene latex is 200nm-500nm, and the median particle size d50 is 350nm.
After the reaction kettle is operated for one year according to the technical process, material skinning appears on the heat exchange tube bundle, the heat exchange tube bundle is required to be cleaned by stopping, and the viscosity of the butadiene latex of the final product is 8000 centipoise.
Numerical simulation is carried out again on the reaction kettle and the stirrer after the heat exchange tube bundle is arranged according to the included angle, and the fluid speed and the turbulence level at the wall surface of the reaction kettle are improved by about 20 percent.
Comparative example 1
The volume of the reaction kettle is 60m 3 The diameter T of the reaction kettle is 3.7m, the height H of the cylinder body is 6.2m, the stirrer in the reaction kettle is a three-layer four-oblique-blade turbine blade, the diameter of the blade is 1.5m, and the distances from the three-layer blade to the bottom of the reaction kettle are respectively 0.9m,2.6m and 4.1m. The reaction kettle is internally provided with 8 groups of heat exchange tube bundles which are uniformly distributed, each group of heat exchange tube bundles is provided with 6 heat exchange tubes, and the radial included angle between the heat exchange tube bundles and the cylinder body is 0 degree.
Stirring was started and the stirring speed N was set at 0.5rev/s.
Adding desalted water at 50 ℃ into the reaction kettle, starting stirring, vacuumizing from a gas outlet 5 by using a vacuum pump, introducing nitrogen from a gas inlet 4, and performing operation for replacing the air in the kettle for multiple times. Under the vacuum condition, the mixture ratio of the water-containing emulsifying agent, the initiator aqueous solution, the styrene and the butadiene is 1:1:0.3:4, wherein the feeding amount of butadiene was 12000kg. And introducing a refrigerant into the heat exchange tube bundle while feeding, wherein the refrigerant inlet amount is 80000kg/h. During the reaction, sampling analysis is carried out, when the conversion rate reaches 25%, the butadiene is added as a raw material, and the ratio of the butadiene addition amount to the initial addition amount is 2:1, the butadiene as a raw material is added for the second time when the conversion rate is 50%, and the ratio of the butadiene addition amount to the initial addition amount is 1.5:1, butadiene is added as a raw material when the conversion rate is 75%, and the ratio of the butadiene addition amount to the initial addition amount is 1:1, adding a polymerization inhibitor when the conversion rate is 90%, and ending the reaction. The axial temperature difference in the reaction kettle is 5 ℃ in the reaction process. The whole reaction process is carried out for 50 hours at 70 ℃, sampling analysis is carried out on materials, the content of emulsifying agent in water phase in the materials is 0.5%, the particle size distribution of polybutadiene latex is 500nm-2000nm, and the median particle size d50 is 1200nm. After the reaction kettle is operated for three months according to the technical process, material skinning appears on the heat exchange tube bundle, and the heat exchange tube bundle needs to be cleaned after stopping.
Comparative example 2
The volume of the reaction kettle is 60m 3 The diameter T of the reaction kettle is 3.7m, the height H of the cylinder body is 6.2m, the stirrer in the reaction kettle is a three-layer four-oblique-blade turbine blade, the diameter of the blade is 1.5m, and the distances from the three-layer blade to the bottom of the reaction kettle are respectively 0.9m,2.6m and 4.1m. The reaction kettle is internally provided with 8 groups of heat exchange tube bundles which are uniformly distributed, each group of heat exchange tube bundles is provided with 6 heat exchange tubes, and the radial included angle between the heat exchange tube bundles and the cylinder body is 15 degrees.
Stirring was started and the stirring speed N was set at 0.5rev/s.
Adding desalted water at 50 ℃ into the reaction kettle, starting stirring, vacuumizing from a gas outlet 5 by using a vacuum pump, introducing nitrogen from a gas inlet 4, and performing operation for replacing the air in the kettle for multiple times. Under the vacuum condition, the mixture ratio of the water-containing emulsifying agent, the initiator aqueous solution, the styrene and the butadiene is 1:1:0.3:4, wherein the feeding amount of butadiene was 12000kg. And feeding a refrigerant into the heat exchange tube bundle at the same time, wherein the refrigerant feeding amount is 72000kg/h. During the reaction, sampling analysis is carried out, when the conversion rate reaches 25%, the butadiene is added as a raw material, and the ratio of the butadiene addition amount to the initial addition amount is 2:1, the butadiene as a raw material is added for the second time when the conversion rate is 50%, and the ratio of the butadiene addition amount to the initial addition amount is 1.5:1, butadiene is added as a raw material when the conversion rate is 75%, and the ratio of the butadiene addition amount to the initial addition amount is 1:1, adding a polymerization inhibitor when the conversion rate is 90%, and ending the reaction. The axial temperature difference in the reaction kettle is 4 ℃ in the reaction process. The whole reaction process is carried out for 40 hours at 70 ℃, sampling analysis is carried out on materials, the content of emulsifying agent in water phase in the materials is 0.4%, the particle size distribution of polybutadiene latex is 500nm-1800nm, and the median particle size d50 is 1000nm. After the reaction kettle is operated for six months according to the technical process, material skinning appears on the heat exchange tube bundle, and the heat exchange tube bundle needs to be cleaned after stopping.
Comparative example 3
The volume of the reaction kettle is 60m 3 The diameter T of the reaction kettle is 3.7m, the height H of the cylinder body is 6.2m, and the diameter D of the stirrer is 3.33m. The stirrer height h was 4.34m. The width of the blade end of the wide blade part is 0.5m, and the width of the blade root is 1m. The length L2 of the narrow blade is 3.7m, the length L1 of the serrated opening is 3.4m, the number of serrations is 28, the width of the uppermost part of the narrow blade is 0.25m, the width of the lowermost part of the narrow blade is 0.5m, and the width gradually becomes smaller from bottom to top. 8 groups of heat exchange tube bundles are uniformly distributed in the reaction kettle, each group of heat exchange tube bundles has 6 heat exchange tubes, and the included angle beta between the heat exchange tube bundles and the radial direction of the cylinder body is 30 degrees. Each blade is provided with 5 circular through holes with the diameter of 0.2m, and the circular through holes are positioned at the saw-tooth-shaped opening parts of the wide blade and the narrow blade.
Stirring was started and the stirring speed N was set at 0.5rev/s.
Adding desalted water at 50 ℃ into the reaction kettle, starting stirring, vacuumizing from a gas outlet 5 by using a vacuum pump, introducing nitrogen from a gas inlet 4, and performing operation for replacing the air in the kettle for multiple times. Under the vacuum condition, the mixture ratio of the water-containing emulsifying agent, the initiator aqueous solution, the styrene and the butadiene is 1:1:0.3:4, wherein the feeding amount of butadiene was 12000kg. And introducing a refrigerant into the heat exchange tube bundle while feeding, wherein the refrigerant inlet amount is 56000kg/h. During the reaction, sampling analysis is carried out, when the conversion rate reaches 25%, the butadiene is added as a raw material, and the ratio of the butadiene addition amount to the initial addition amount is 2:1, the butadiene as a raw material is added for the second time when the conversion rate is 50%, and the ratio of the butadiene addition amount to the initial addition amount is 1.5:1, butadiene is added as a raw material when the conversion rate is 75%, and the ratio of the butadiene addition amount to the initial addition amount is 1:1, adding a polymerization inhibitor when the conversion rate is 90%, and ending the reaction. The axial temperature difference in the reaction kettle is 0.8 ℃ in the reaction process. The whole reaction process is carried out for 28h at 70 ℃, sampling analysis is carried out on materials, no emulsifying agent is detected in the water phase of the product, emulsion breaking occurs in the emulsion, the particle size distribution of the polybutadiene latex is 200nm-300nm, the median particle size d50 is 250nm, but emulsion residues occur in the sample, and the quality of the product is not in accordance with the requirements.
Example 3
The reactor of example 1 was used. Adding desalted water at 50 ℃ into the reaction kettle, starting stirring, vacuumizing from a gas outlet 5 by using a vacuum pump, introducing nitrogen from a gas inlet 4, and performing operation for replacing the air in the kettle for multiple times. Under the vacuum condition, the mixture ratio of the water-containing emulsifying agent, the initiator aqueous solution, the styrene and the butadiene is 1:1:0.3:4, adding the mixture into a kettle in proportion, sampling and analyzing during the reaction, and adding butadiene as a raw material when the conversion rate reaches 25%, wherein the proportion of the additional amount of butadiene to the initial addition amount is 2:1, the butadiene as a raw material is added for the second time when the conversion rate is 50%, and the ratio of the butadiene addition amount to the initial addition amount is 1.5:1, butadiene is added as a raw material when the conversion rate is 75%, and the ratio of the butadiene addition amount to the initial addition amount is 1:1, adding a polymerization inhibitor when the conversion rate is 90%, and ending the reaction. The whole reaction process is carried out for 20 hours at 80 ℃, the content of emulsifying agent in the water phase of the material is 0.001%, the particle size distribution of the polybutadiene latex is 180nm-450nm, the median particle size d50 is 280nm, and a small amount of unknown impurities appear in the product due to the higher reaction temperature.
Example 4
The reactor of example 1 was used. Adding desalted water at 50 ℃ into the reaction kettle, starting stirring, vacuumizing from a gas outlet 5 by using a vacuum pump, introducing nitrogen from a gas inlet 4, and performing operation for replacing the air in the kettle for multiple times. Under the vacuum condition, the mixture ratio of the water-containing emulsifying agent, the initiator aqueous solution, the styrene and the butadiene is 1.2:1:0.3:4, adding the mixture into a kettle in proportion, sampling and analyzing during the reaction, and adding butadiene as a raw material when the conversion rate reaches 25%, wherein the proportion of the additional amount of butadiene to the initial addition amount is 2:1, the butadiene as a raw material is added for the second time when the conversion rate is 50%, and the ratio of the butadiene addition amount to the initial addition amount is 1.5:1, butadiene is added as a raw material when the conversion rate is 75%, and the ratio of the butadiene addition amount to the initial addition amount is 1:1, adding a polymerization inhibitor when the conversion rate is 90%, and ending the reaction. The whole reaction process is carried out for 25h at 70 ℃, the materials are sampled and analyzed, the content of the emulsifier in the water phase in the sample is 0.3%, the residual quantity is too high, the particle size distribution of the polybutadiene latex is 250nm-350nm, and the median particle size d50 is 300nm.
Example 5
The reactor of example 1 was used. Adding desalted water at 50 ℃ into the reaction kettle, starting stirring, vacuumizing from a gas outlet 5 by using a vacuum pump, introducing nitrogen from a gas inlet 4, and performing operation for replacing the air in the kettle for multiple times. Under the vacuum condition, the mixture ratio of the water-containing emulsifying agent, the initiator aqueous solution, the styrene and the butadiene is 1.5:1:0.3:4, adding the mixture into a kettle in proportion, sampling and analyzing during the reaction, and adding butadiene as a raw material when the conversion rate reaches 25%, wherein the proportion of the additional amount of butadiene to the initial addition amount is 2:1, the butadiene as a raw material is added for the second time when the conversion rate is 50%, and the ratio of the butadiene addition amount to the initial addition amount is 1.5:1, butadiene is added as a raw material when the conversion rate is 75%, and the ratio of the butadiene addition amount to the initial addition amount is 1:1, adding a polymerization inhibitor when the conversion rate is 90%, and ending the reaction. The whole reaction process is carried out for 25h at 70 ℃, the materials are sampled and analyzed, the content of the emulsifier in the water phase in the sample is 0.7%, the residual quantity is too high, the particle size distribution of the polybutadiene latex is 280nm-400nm, and the median particle size d50 is 320nm.
Finally, it should be noted that the above embodiments are only described as preferred embodiments of the present invention, and not limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that various modifications and improvements made to the technical solution of the present invention or equivalent substitutions should be made, all fall within the scope of the present invention as defined in the claims.
Claims (8)
1. An emulsion polymerization reaction kettle comprises a vertical cylinder body (1), wherein the upper end socket of the cylinder body (1) is provided with a material inlet (2), a gas inlet (4) and a gas outlet (5), the gas outlet (5) is connected with a vacuum system, and the lower end socket is provided with a material outlet (3); a stirring shaft insertion port is formed in the upper end socket of the cylinder body (1), one end of the stirring shaft is connected with the power device (8), the other end of the stirring shaft is connected with the four-blade ring type stirrer (7), and the stirring shaft is connected with the cylinder body through a mechanical seal;
the four-blade ring stirrer (7) consists of four blades which are respectively fixed on an upper hub (11) and a lower hub (12), wherein a wide blade (15) fixed on the lower hub (12) is gradually narrowed from a blade root (16) to a blade end (17) at the hub, a narrow blade (13) in the vertical direction is connected with the wide blade end (17), and the other end of the narrow blade (13) is connected with the upper hub (11) through a fixing part (18); the upper part of the narrow blade (13) is provided with a serration opening, the width of the narrow blade gradually narrows from bottom to top, the ratio of the serration opening length L1 to the height h of the stirrer is between 0.4 and 0.8, and the number m of the serration is between 3 and 25.
2. The emulsion polymerization reaction kettle as claimed in claim 1, wherein heat exchange tube bundles (10) are arranged in the barrel, an included angle is formed between the heat exchange tube bundles and the radial direction of the barrel, beta is between 15 degrees and 45 degrees, the number of the heat exchange tube bundles is 4-8 groups, and the number of single tubes in each group is 3-6.
3. The emulsion polymerization reactor of claim 1 wherein the ratio of stirrer diameter D to barrel diameter T ranges from 0.6 to 0.9 depending on the product viscosity, when product viscosity is <1000cp, D/T = 0.6; when the final viscosity of the product is 1000-5000cp, d/t=0.6-0.8; when the product viscosity is 5000-10000cp, d/t=0.8-0.9.
4. Emulsion polymerization reactor according to claim 1, characterized in that the angle between adjacent blades is 90 degrees and the ratio α of the width W1 of the blade end (17) to the width W2 of the blade root (16) is between 0.3 and 0.5.
5. The emulsion polymerization reactor of claim 1 wherein the ratio of serrated opening length L1 to narrow blade length L2 to the ratio n of light liquid level to heavy liquid level in the reactor is: l1/l2=n+0.2.
6. The emulsion polymerization reactor of claim 1 wherein the number of serrations m on the narrow blades as a function of system to shear force γ is: m=ndγ, N is the stirring rotation speed.
7. The emulsion polymerization reactor as claimed in claim 1, characterized in that the lower parts of the wide blades (15) and the narrow blades (13) of the four-bladed ring stirrer (7) are provided with circular through holes, the ratio of the diameter of the circular through holes to the diameter D of the stirrer is between 0.01 and 0.08, and the ratio of the area of the circular through holes to the area of the blades is between 0.05 and 0.15.
8. The emulsion polymerization reactor of claim 2 wherein β is related to the fluid velocity V at a heat exchange tube nearest the reactor wall by: beta=90v.
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