Method for mixing for coating bitumen reactors

Abstract

The application discloses a stirring method for coating an asphalt reactor, comprising the following steps: an oxidation reaction stage: introducing an oxidizing gas into a reaction kettle, and controlling a stirring assembly to operate in a first operating state, using a lower layer shear type stirring paddle to provide shearing action to disperse the gas, and using an upper layer circulating type stirring paddle to maintain a gas-liquid mixed flow field; a stripping stage: stopping the introduction of the oxidizing gas, introducing a stripping medium into the reaction kettle, and controlling the stirring assembly to operate in a second operating state, the stirring intensity of the second operating state being lower than that of the first operating state, so as to reduce the shearing action and maintain full-kettle circulation, and avoid bubbles from being difficult to escape under a heterogeneous fluid system due to too fine shearing. The method can adapt to a large change in material viscosity, and improves the uniformity and production stability of products.

Description

Technical Field

[0001] This invention relates to mixing technology, specifically a mixing method for coating asphalt reactors. Background Technology

[0002] Asphalt coating is a key material for coating the surface of lithium-ion battery anode materials. Its production process typically includes two core stages: oxidative polymerization of ethylene tar and steam stripping. These two stages have significantly different, even contradictory, requirements for the stirring flow field: the oxidation reaction stage mainly involves a gas-liquid two-phase reaction, requiring extremely strong shear force to break the introduced oxidizing gas into tiny bubbles to increase the gas-liquid contact area and promote the reaction; while the stripping stage requires the removal of dissolved small molecule light components and bubbles from the liquid phase in a high-viscosity system. If high shear force is maintained in this stage, the bubbles are easily cut too finely, causing them to be unable to coalesce and float in the viscous liquid, resulting in severe bubble entrainment or flooding, affecting product quality and production stability.

[0003] Existing stirring systems or methods typically employ a single impeller combination or a constant operating mode, making it difficult to simultaneously address the two drastically different process requirements mentioned above. For example, if the design focuses on the high shear of the oxidation stage, excessive shear can easily lead to difficulties in devolatilization during the stripping stage; if the design focuses on circulating mixing, the gas-liquid dispersion effect is poor and the reaction efficiency is low during the oxidation stage. Furthermore, as the reaction proceeds, the material viscosity can rise sharply from tens of millipascals per second to thousands of millipascals per second. Conventional stirring methods can easily create flow dead zones on the reactor walls or bottom, leading to localized overheating and coking, and are difficult to adapt to the flow field challenges brought about by the large changes in viscosity throughout the reactor. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a stirring method for coating asphalt reactors, which can adapt to large changes in material viscosity and improve product uniformity and production stability.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a stirring method for a coated asphalt reactor, wherein a stirring system is used to process the reactants, the stirring system comprising a reactor and stirring components disposed within the reactor, the stirring components being arranged in layers in the vertical direction, including a shear-type stirring blade located in the lower layer and a circulation-type stirring blade located in the upper layer;

[0006] The method includes the following steps:

[0007] Oxidation reaction stage: Oxidizing gas is introduced into the reactor and the stirring assembly is controlled to operate in the first operating state. The lower shear-type stirring paddle provides shearing action to disperse the gas, and the upper circulating stirring paddle maintains the gas-liquid mixing flow field.

[0008] Stripping stage: Stop the introduction of oxidizing gas, introduce stripping medium into the reactor, and control the stirring component to operate in the second operating state. The stirring intensity of the second operating state is lower than that of the first operating state, so as to reduce the shearing effect and maintain the whole reactor circulation, and avoid bubbles from being unable to escape in the heterogeneous fluid system due to excessive shearing.

[0009] As a further improvement of the present invention, the lower shear-type impeller is a disc turbine impeller; the upper circulation-type impeller is an axial flow impeller.

[0010] As a further improvement of the present invention, the blades of the disc turbine impeller adopt a parabolic blade structure, and the blade ends of the disc turbine impeller are provided with a tuning fork structure or a blade tip differential structure to enhance the ability to break up the gas-liquid interface.

[0011] As a further improvement of the present invention, in the oxidation reaction stage, the first operating state satisfies at least one of the following parameter conditions:

[0012] The blade tip linear velocity of the stirring assembly is controlled at 6.0~7.0 m / s;

[0013] The power consumption per unit volume of the stirring system is controlled at 1.0~2.5kW / m³. 3 ;

[0014] The average volumetric shear rate generated by the stirring system in the material is not less than 50 s⁻ 1 .

[0015] As a further improvement of the present invention, in the stripping stage, the second operating state satisfies at least one of the following parameter conditions:

[0016] The blade tip linear velocity of the stirring assembly is controlled at 1.5~3.5m / s;

[0017] The power consumption per unit volume of the stirring system is controlled at 0.3~1.0 kW / m³. 3 ;

[0018] The average volumetric shear rate generated by the stirring system in the material is no higher than 30 s⁻ 1 .

[0019] As a further improvement of the present invention, the method further includes a discharge stage after the stripping stage; in the discharge stage, the stirring assembly is maintained in the second operating state and steam purging is carried out during the unloading process; the number of stirring cycles in the stripping stage and the discharge stage is controlled at 8 to 12 times / minute; in the oxidation reaction stage, the number of cycles of the stirring system is controlled at ≥15 times / minute.

[0020] As a further improvement of the present invention, the ratio of the shear-type stirring paddle to the inner diameter of the reactor is 0.4 to 0.55; the ratio of the diameter of the circulating stirring paddle to the inner diameter of the reactor is 0.55 to 0.70.

[0021] As a further improvement of the present invention, the stirring system further includes an annular gas distributor arranged at the bottom of the reactor, the annular gas distributor having an upward-opening gas outlet; in the oxidation reaction stage and the stripping stage, the oxidizing gas and the stripping medium both enter the reactor through the annular gas distributor, and the upward gas outlet direction prevents gas aggregation; the outlet gas velocity is 12m / s±15%, and the annular tube opening ratio of the opening flow area / annular tube cross-sectional flow area is 80~90%.

[0022] As a further improvement of the present invention, the stirring system further includes a tubular baffle disposed inside the reactor; the method includes using the tubular baffle for heat exchange and rectification, adopting segmented heat exchange to ensure heat exchange requirements at different liquid levels and avoid dry burning and coking.

[0023] As a further improvement of the present invention, the reactor adopts an elliptical head structure that is larger at the top and smaller at the bottom; the method includes gas-liquid separation using the upper space provided by the elliptical head structure.

[0024] The beneficial effects of this invention lie in its layered arrangement of shear-type and circulating mixing components, combined with differentiated staged operation control, which effectively resolves the conflicting flow field requirements at different stages of asphalt coating production. In the oxidation reaction stage, the first operating state, coupled with the lower shear impeller, provides a strong shear environment, improving gas dispersion and reaction rate. In the stripping stage, switching to a lower-intensity second operating state, utilizing the upper circulating impeller to maintain full-bottle flow, reduces shear damage and prevents bubbles from escaping due to excessive shearing in a heterogeneous fluid system. This targeted process adapts to significant changes in material viscosity, improving product uniformity and production stability. Attached Figure Description

[0025] Figure 1 These are the velocity cloud map and velocity vector map of the present invention;

[0026] Figure 2 Velocity contour plots for different cross sections of this invention; Detailed Implementation

[0027] Reference Figure 1-2As shown, this embodiment provides a stirring method for a coated asphalt reactor, which uses a stirring system to process the reactants. The stirring system includes a reactor and stirring components disposed within the reactor. The stirring components are arranged in layers in the vertical direction, including a shear-type stirring blade in the lower layer and a circulation-type stirring blade in the upper layer.

[0028] The method includes the following steps:

[0029] Oxidation reaction stage: Oxidizing gas is introduced into the reactor and the stirring assembly is controlled to operate in the first operating state. The lower shear-type stirring paddle provides shearing action to disperse the gas, and the upper circulating stirring paddle maintains the gas-liquid mixing flow field.

[0030] Stripping stage: Stop the introduction of oxidizing gas, introduce stripping medium into the reactor, and control the stirring component to operate in the second operating state. The stirring intensity of the second operating state is lower than that of the first operating state, so as to reduce the shearing effect and maintain the whole reactor circulation, and avoid bubbles from being unable to escape in the heterogeneous fluid system due to excessive shearing.

[0031] The stirring assembly is connected to the top or bottom of the reactor via a bearing structure to ensure stable rotation within the reactor. Oxidizing gas and stripping medium are introduced through a pre-reserved gas inlet channel on the reactor, which is connected to a subsequently installed gas distributor to achieve uniform gas input. During the oxidation reaction stage, when the stirring assembly operates in its first state, the lower shear-type stirring paddle rotates at high speed, generating strong shear force to break the introduced oxidizing gas into fine bubbles, increasing the gas-liquid contact area. Meanwhile, the upper circulating stirring paddle rotates synchronously, driving the material in the reactor to form a circulating flow, avoiding gas-liquid stratification, maintaining a stable gas-liquid mixing flow field, and thus promoting the efficient progress of the oxidative polymerization reaction. After entering the stripping stage, the stirring assembly switches to a second operating state with lower stirring intensity. At this time, the shearing effect is weakened, which can prevent bubbles from being excessively cut and unable to coalesce and float. At the same time, the upper circulating stirring paddle can still maintain the circulating flow of the entire reactor material, allowing the stripping medium to fully contact the material, preventing bubbles from being unable to escape in a heterogeneous fluid system due to excessive shearing. This effectively alleviates the contradiction between the flow field requirements of different reaction stages and improves the stability of the production process.

[0032] To facilitate further optimization of the shearing and circulation effects of the mixing components, in one optional embodiment, the lower shearing impeller is a disc turbine impeller, and the upper circulation impeller is an axial flow impeller.

[0033] The disc turbine agitator is fixedly connected to the agitator shaft via a hub, and the axial flow agitator is also mounted on the agitator shaft via a matching connection structure. Both are arranged in layers vertically, with the lower disc turbine agitator near the bottom of the reactor and the upper axial flow agitator located in the upper-middle region. During the oxidation reaction stage, the disc turbine agitator, acting as a shear-type agitator, generates stronger shear force due to its structural characteristics, more efficiently dispersing oxidizing gases into microbubbles and improving gas-liquid mass transfer efficiency. The upper axial flow agitator generates stronger axial circulation driving force, ensuring thorough mixing of the upper and lower layers of material within the reactor, further preventing stratification and resulting in more uniform concentration and temperature in the reaction system. Simultaneously, during the stripping stage, the circulation effect of the axial flow agitator better complements low-intensity stirring, ensuring effective contact between all materials in the reactor and the stripping medium, promoting the escape of light components, and further improving the adaptability of the agitation system to different reaction stages.

[0034] Further optimization can be achieved by selecting the following method: the blades of the disc turbine impeller adopt a parabolic blade structure, and the blade ends of the disc turbine impeller are provided with a tuning fork structure or a blade tip differential structure to enhance the ability to break up the gas-liquid interface.

[0035] The blades of the disc turbine agitator are fixed to the hub by welding or bolting. The blades adopt a parabolic blade shape design, and the tuning fork structure or blade tip differential structure at the blade tip is integrally formed with the blade or assembled through a detachable connection. During the oxidation reaction stage, when the disc turbine agitator rotates, the parabolic blade shape optimizes the fluid flow trajectory and reduces energy loss. At the same time, the tuning fork structure or blade tip differential structure at the blade tip further enhances the disturbance and breaking effect on the gas-liquid interface, breaking the oxidizing gas into smaller bubbles, significantly increasing the gas-liquid contact area, improving the uniformity of gas dispersion, thereby promoting the full progress of the oxidation reaction and improving reaction efficiency and product quality uniformity.

[0036] In some options, during the oxidation reaction phase, the first operating state satisfies at least one of the following parameter conditions:

[0037] The blade tip linear velocity of the stirring assembly is controlled at 6.0~7.0 m / s;

[0038] The power consumption per unit volume of the stirring system is controlled at 1.0~2.5kW / m³. 3 ;

[0039] The average volumetric shear rate generated by the stirring system in the material is not less than 50 s⁻ 1 .

[0040] The blade tip linear velocity, power consumption per unit volume, and average volumetric shear rate of the stirring assembly are achieved by matching the structural parameters of the variable frequency drive and the stirring assembly. The variable frequency drive is connected to the stirring shaft to adjust the stirring speed, thereby controlling the relevant parameters. During the oxidation reaction stage, controlling the parameters of the first operating state within the above range ensures that the stirring assembly provides sufficient shear energy to effectively overcome the material viscosity in the middle of the reaction, fully shear and disperse the oxidizing gas, and meet the mass transfer efficiency requirements of the gas-liquid two-phase reaction. At the same time, appropriate power consumption per unit volume can reduce energy waste and improve the economy of the reaction process while ensuring the reaction effect.

[0041] To better adapt the stirring effect during the stripping stage to the process requirements, in one optional embodiment, the second operating state during the stripping stage satisfies at least one of the following parameter conditions:

[0042] The blade tip linear velocity of the stirring assembly is controlled at 1.5~3.5m / s;

[0043] The power consumption per unit volume of the stirring system is controlled at 0.3~1.0 kW / m³. 3 ;

[0044] The average volumetric shear rate generated by the stirring system in the material is no higher than 30 s⁻ 1 .

[0045] The aforementioned parameters are also adjusted by regulating the stirring speed using a variable frequency drive, echoing the parameter control logic of the oxidation reaction stage. During the stripping stage, controlling the parameters of the second operating state within the aforementioned low-intensity range significantly reduces shear stress, preventing excessive shearing of bubbles that hinders their coalescence and upward movement. Simultaneously, maintaining appropriate power consumption per unit volume and blade tip linear velocity ensures that the upper circulating impeller can drive the circulation of material throughout the reactor, allowing for full contact between the stripping medium and the material. This promotes the smooth escape of light components, alleviates bubble entrainment or flooding, and improves stripping efficiency and product quality.

[0046] Furthermore, the method also includes a discharge stage after the stripping stage; in the discharge stage, the stirring assembly is maintained in the second operating state and steam purging is carried out during the unloading process; the number of stirring cycles in the stripping stage and the discharge stage is controlled at 8 to 12 times / minute; in the oxidation reaction stage, the number of cycles of the stirring system is controlled at ≥15 times / minute.

[0047] During the discharge stage, the stirring components maintain the same second operating state as in the stripping stage, with a stable stirring speed maintained by a frequency converter. The steam purging device is connected to the inside of the reactor through a purging channel on the reactor, with the outlet of the purging channel facing the inner wall of the reactor and the stirring components. Maintaining low-intensity stirring during the discharge stage prevents material accumulation inside the reactor. Combined with steam purging, high-temperature steam washes over the inner wall of the reactor and the surface of the stirring components, reducing the adhesion of residual material. Simultaneously, the stirring action promotes full contact between residual material and steam, accelerating the unloading process. Controlling the stirring cycle frequency to 8-12 times / minute ensures effective unloading while avoiding increased energy consumption due to excessive stirring, and also reduces contamination of the equipment by residual material, facilitating subsequent cleaning and maintenance. During the oxidation reaction stage, controlling the cycle frequency to ≥15 times / minute ensures uniform distribution of reaction heat and material concentration, reduces localized overheating, further promotes uniform oxidation, and improves product quality stability.

[0048] In some embodiments, the ratio of the shear-type agitator to the inner diameter of the reactor is 0.4 to 0.55; the ratio of the diameter of the circulation-type agitator to the inner diameter of the reactor is 0.55 to 0.70.

[0049] The diameters of the shear-type and circulating-type agitators are designed proportionally to the inner diameter of the reactor. The number of cycles in the agitation system is achieved by adjusting the stirring speed and agitator structural parameters. A suitable agitator diameter ratio design ensures that, in high-viscosity material systems, the agitator can effectively drive viscous materials in the reactor wall area, eliminate flow dead zones, and achieve uniform mixing of materials throughout the reactor.

[0050] To optimize gas input and dispersion, in one optional embodiment, the stirring system further includes an annular gas distributor arranged at the bottom of the reactor. The annular gas distributor has upward-facing outlet holes. During the oxidation reaction stage and the stripping stage, both the oxidizing gas and the stripping medium enter the reactor through the annular gas distributor, and the upward outlet direction prevents gas aggregation. The outlet gas velocity is 12 m / s ± 15%, and the annular pipe opening ratio (opening flow area / annular pipe cross-sectional flow area) is 80-90%.

[0051] The annular gas distributor is fixedly installed at the bottom of the reactor by a bracket. Its inlet is sealed to the reactor's inlet channel, and the outlets are evenly distributed at the top of the annular gas distributor. During the oxidation and stripping stages, the oxidizing gas and stripping medium enter the annular gas distributor through the inlet channel and are evenly sprayed out through the upward-opening outlets. The upward direction of the outlet allows the gas to fully interact with the flow field generated by the agitator during its ascent, effectively preventing gas aggregation and making the bubbles more evenly dispersed. At the same time, the annular structure ensures complete gas coverage at the bottom of the reactor, improving the comprehensiveness of gas-liquid contact and further improving the effectiveness of the oxidation and stripping processes. Moreover, the above-mentioned parameter design makes the effect more stable.

[0052] Specifically, the following structural design can also be adopted: the stirring system further includes a tubular baffle set inside the reactor; the method includes using the tubular baffle for heat exchange and rectification, adopting segmented heat exchange to ensure heat exchange requirements at different liquid levels and avoid dry burning and coking.

[0053] The tubular baffles are connected to the inner wall of the reactor via fixed supports, ensuring their stability within the reactor. The heat transfer medium circulates within the tubular baffles, achieving heat exchange. During the reaction, the tubular baffles rectify the fluid flow within the reactor, optimizing the flow field distribution and reducing eddies and dead zones. Simultaneously, the circulating flow of the heat transfer medium facilitates heat exchange, promptly removing heat generated during the reaction or replenishing the heat required for the reaction, maintaining a stable reaction temperature and preventing coking caused by localized overheating. Furthermore, the rectification effect, combined with the stirring action of the agitator, further enhances the uniformity of material mixing.

[0054] To improve the gas-liquid separation effect, in one optional scheme, the reactor adopts an elliptical head structure that is larger at the top and smaller at the bottom; the method includes using the upper space provided by the elliptical head structure for gas-liquid separation.

[0055] The main body of the reactor is sealed and fixed to the elliptical head by welding or flange connection, forming an integral structure that is larger at the top and smaller at the bottom. During the reaction process, especially in the stripping stage, the elliptical head structure provides a larger upper gas phase space. When light components evaporate from the liquid phase, there is more time for gas-liquid separation in this upper space, reducing liquid entrainment and improving the removal efficiency of light components. At the same time, the structure of larger at the top and smaller at the bottom can optimize the flow trajectory of the fluid inside the reactor. Combined with the circulation effect of the stirring components, it further improves the flow field distribution of the entire reactor and enhances the reaction and stripping effects.

[0056] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A stirring method for a coated asphalt reactor, characterized in that, The reaction materials are processed using a stirring system, which includes a reaction vessel and stirring components disposed within the reaction vessel. The stirring components are arranged in layers in the vertical direction, including a shear-type stirring blade located in the lower layer and a circulation-type stirring blade located in the upper layer. The method includes the following steps: Oxidation reaction stage: Oxidizing gas is introduced into the reactor and the stirring assembly is controlled to operate in the first operating state. The lower shear-type stirring paddle provides shearing action to disperse the gas, and the upper circulating stirring paddle maintains the gas-liquid mixing flow field. Stripping stage: Stop the introduction of oxidizing gas, introduce stripping medium into the reactor, and control the stirring component to operate in the second operating state. The stirring intensity of the second operating state is lower than that of the first operating state, so as to reduce the shearing effect and maintain the whole reactor circulation, and avoid bubbles from being unable to escape in the heterogeneous fluid system due to excessive shearing.

2. The stirring method for a coated asphalt reactor according to claim 1, characterized in that, The lower shear-type impeller is a disc turbine impeller; the upper circulation-type impeller is an axial flow impeller.

3. The stirring method for a coated asphalt reactor according to claim 2, characterized in that, The blades of the disc turbine impeller adopt a parabolic blade structure, and the blade ends of the disc turbine impeller are provided with a tuning fork structure or blade tip differential structure to enhance the ability to break up the gas-liquid interface.

4. The stirring method for a coated asphalt reactor according to claim 1, characterized in that, During the oxidation reaction phase, the first operating state satisfies at least one of the following parameter conditions: The blade tip linear velocity of the stirring assembly is controlled at 6.0~7.0 m / s; The power consumption per unit volume of the stirring system is controlled at 1.0~2.5kW / m³. 3 ; The average volumetric shear rate generated by the stirring system in the material is not less than 50 s⁻ 1 .

5. The stirring method for a coated asphalt reactor according to claim 1 or 4, characterized in that, During the stripping stage, the second operating state satisfies at least one of the following parameter conditions: The blade tip linear velocity of the stirring assembly is controlled at 1.5~3.5m / s; The power consumption per unit volume of the stirring system is controlled at 0.3~1.0 kW / m³. 3 ; The average volumetric shear rate generated by the stirring system in the material is no higher than 30 s⁻ 1 .

6. The stirring method for a coated asphalt reactor according to claim 1, characterized in that, The method further includes a discharge stage after the stripping stage; in the discharge stage, the stirring assembly is maintained in the second operating state and steam purging is carried out during the unloading process; the number of stirring cycles in the stripping stage and the discharge stage is controlled at 8 to 12 times / minute; During the oxidation reaction stage, the number of cycles of the stirring system is controlled to be ≥15 times / minute.

7. The stirring method for a coated asphalt reactor according to claim 1, characterized in that, The ratio of the diameter of the shear-type agitator to the inner diameter of the reactor is 0.4 to 0.55; the ratio of the diameter of the circulation-type agitator to the inner diameter of the reactor is 0.55 to 0.

70.

8. The stirring method for a coated asphalt reactor according to claim 1, characterized in that, The stirring system also includes an annular gas distributor arranged at the bottom of the reactor. The annular gas distributor has an upward-opening gas outlet. During the oxidation reaction stage and the stripping stage, the oxidizing gas and the stripping medium both enter the reactor through the annular gas distributor. The upward gas outlet direction prevents gas aggregation. The outlet gas velocity is 12m / s±15%, and the annular pipe opening ratio of the opening flow area to the annular pipe cross-sectional flow area is 80~90%.

9. The stirring method for a coated asphalt reactor according to claim 1, characterized in that, The stirring system also includes tubular baffles installed inside the reactor; the method includes using the tubular baffles for heat exchange and rectification, employing segmented heat exchange to ensure heat exchange requirements at different liquid levels and avoid dry burning and coking.

10. The stirring method for a coated asphalt reactor according to claim 1, characterized in that, The reactor adopts an elliptical head structure that is larger at the top and smaller at the bottom; the method includes using the upper space provided by the elliptical head structure for gas-liquid separation.

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