How do dissolving and stirring tanks achieve rapid and uniform dispersion of high-viscosity materials with solvents?
Publish Time: 2025-12-12
As a core mixing device, the dissolving and stirring tank plays a crucial role in efficiently dispersing and dissolving solid or powdered materials in solvents. Especially when dealing with high-viscosity systems, materials exhibit poor flowability, high mass transfer resistance, and are prone to agglomeration or "fisheye" phenomena. Traditional stirring methods are often inefficient or even fail to achieve uniform dissolution. To address this, modern dissolving and stirring tanks employ a multi-dimensional collaborative design—from stirring structure and flow field control to temperature control and feeding strategies—to systematically solve the problem of dispersing high-viscosity materials.
1. Stirring System: Multi-stage Blade Combination Breaks Through Viscosity Barriers
Mixing high-viscosity materials cannot rely on a single stirring method. Dissolving and stirring tanks typically employ a composite stirring system: anchor or frame blades are positioned at the bottom, rotating slowly close to the tank wall to scrape off adhering materials and promote overall circulation; propeller or ribbon blades are used in the middle or upper sections to generate strong axial flow, pushing materials in the central area towards the tank wall, forming a three-dimensional flow field of "rolling up and down + radial shearing". Some high-end equipment even incorporates planetary agitators or biaxial differential agitators, causing materials to repeatedly experience high strain rate regions through shearing, stretching, and folding, accelerating agglomeration and solvent penetration.
2. Flow Field Optimization: Synergistic Effect of Baffles and Tank Geometry
To prevent high-viscosity fluids from forming "dead zones" or merely rotating synchronously with the impellers during stirring, vertical baffles are often installed on the inner wall of the tank to force the fluid to change direction, enhancing turbulence and shear. Simultaneously, the tank's height-to-diameter ratio is optimized through fluid dynamics simulation to ensure maximum effective volume utilization under limited power. For extremely high viscosity systems, some designs employ conical or sloping bottom structures, combined with bottom scrapers, to prevent material deposition and solidification, ensuring full-volume mixing.
3. Temperature Control and Solvent Strategy: Reducing Viscosity and Increasing Mass Transfer Rate
Temperature is a key variable affecting viscosity. Most dissolving and stirring tanks are equipped with jacketed or internal coil heating/cooling systems, which can moderately raise the temperature in the early stages of dissolution, significantly reducing material viscosity and increasing molecular diffusion rates. Meanwhile, the solvent addition method is also crucial: batch dripping or spraying is used to avoid localized over-dilution or clumping caused by adding a large amount at once; some systems also integrate vacuum degassing, reducing air resistance while promoting solvent penetration into the capillary pores of the powder.
4. Intelligent Control and Process Intensification: From Experience-Based Operation to Precise Regulation
Dissolving and stirring tanks are increasingly integrating intelligent control systems. By monitoring torque, power, temperature, and viscosity in real time, the system can automatically adjust rotation speed, feed rate, and temperature control parameters to ensure operation within the optimal dissolution window. Furthermore, process intensification units such as high-shear emulsifying heads, ultrasonic probes, or static mixers can be integrated into the tank or circulation loop, providing instantaneous high-energy input at critical stages to instantly break down stubborn agglomerates.
Rapid and uniform dispersion of high-viscosity materials cannot be achieved solely through "vigorous stirring," but rather through a comprehensive consideration of material properties, fluid dynamics, thermodynamics, and automated control. Through scientific stirring configurations, optimized tank designs, intelligent process strategies, and necessary process intensification measures, modern dissolving and stirring tanks can efficiently handle a wide range of operating conditions, from low-viscosity solutions to high-viscosity pastes, providing stable, reliable, and scalable dissolving solutions for industrial production.
