Definition
The pilot disperser is a kind of laboratory and small and medium-scale production equipment used for material mixing, dispersion, homogenization and wet grinding. It usually refers to the intermediate experimental scale equipment between laboratory research and development and large-scale industrial production, which is a key link in the process scale-up process. The equipment realizes uniform mixing of multiphase systems through mechanical force, and is widely used in formula research and development and process verification in various industries such as chemicals, coatings, inks, new energy, food and cosmetics.
Principle
The working principle of the pilot disperser is based on the mechanical and hydraulic action generated by the high-speed rotating dispersion disc. The motor rotates at high speed in the container by driving the dispersion disc through a spindle, and the serrated structure on the edge of the dispersion disc generates strong shear forces. As the platter rotates, the material is sucked into the upper and lower areas of the platter, thrown towards the vessel wall under centrifugal force, and then circulated back to the central area of the platter. This process forms a strong vortex and circulation that causes the agglomerated particles to be sheared and broken and fully mixed with the continuous phase. Its core force can be summarized as the comprehensive effect of shear force, impact force and turbulence force. For more demanding nanoscale dispersions, devices are often combined with stator-rotor structures or basket grinding structures to produce stronger shear energy density.
Measurement and evaluation methods
The evaluation of dispersion effect should be combined with process parameters and final product performance indicators. Process monitoring typically involves measuring changes in material viscosity over time or rotational speed, tracking using a rotary viscometer. The final evaluation focuses on the stability and fineness of the dispersion system. The fineness is usually measured by a scraper fineness meter according to relevant standards, and the maximum particle size is judged by observing the appearance of particles in the scratch. Stability can be assessed by observing the resting delamination time, measuring the centrifugal sedimentation rate, or analyzing the particle size distribution using a laser particle size analyzer. For color dispersion systems, colorimeters can be used to compare standard color plates for color difference analysis. These measurements are performed with reference to specific industry standards.
Influencing factors
The dispersion effect is affected by multiple factors. In terms of equipment parameters, the diameter, tooth shape design, and linear speed of the dispersion disc are the key factors. Linear velocity is usually adjusted according to the viscosity of the material and the target particle size. In the process parameters, dispersion time, temperature control and feeding sequence have a direct impact on the results. Material properties include solid content, raw particle size, viscosity and compatibility between components. In addition, the shape and size of the vessel need to be matched to the dispersion disc to ensure efficient flow field circulation. The efficiency of the cooling system also affects the handling of heat-sensitive materials.
Applications
Pilot dispersers play an important role in many industrial research and development fields. In the coatings and inks industry, it is used for the pre-dispersion and stabilization of pigment slurries. In the lithium battery industry, it is used for the development of homogenization processes for positive and negative electrode slurries. In the field of cosmetics, it is used to prepare emulsion systems such as creams and lotions. In the food industry, it is used for the homogenization of sauces and condiments. It is also a common equipment for verifying the feasibility of processes in the preparation of polymer composites, ceramic slurries, nanomaterial suspensions, etc.
Selection considerations
Equipment selection needs to be comprehensively considered based on specific process goals and material characteristics. The throughput is the primary parameter and needs to match the batch range of pilot production. Depending on the viscosity of the material and the desired shear strength, the appropriate power and torque configuration is selected. For processes that require cooling or heating, the temperature control capabilities of jacketed containers should be concerned. If the process includes grinding steps, consider whether to choose an integrated dispersion grinding model. The material of the equipment needs to be evaluated for its chemical resistance to the material, and stainless steel or special coatings are commonly chosen. In terms of safety, explosion-proof design, overload protection and easy-to-clean construction are points of concern. It is recommended to verify the suitability of the equipment for a specific formulation through process trials.