Definition
A high-shear emulsification disperser is a type of equipment that efficiently mixes, disperses, emulsifies, and homogenizes immiscible liquid or solid particles in a liquid medium through mechanical action. Its core function is to generate strong shear, shock, and turbulence, which can quickly reduce the droplet or particle size and form a stable and uniform dispersion system.
Principle
The core working component of the equipment is the rotor-stator structure. The motor drives the rotor to rotate at high speeds within the stator, producing extremely high linear speeds. The material is sucked in from the bottom or side of the equipment and is subjected to strong mechanical shear in the narrow gap between the rotor and the stator. At the same time, the material is thrown towards the stator wall at high speed and is subjected to impact. In this process, there is also a hole effect and turbulence, and these combined mechanical and hydraulic forces cause the agglomerated particles or large droplets to be quickly broken into microscopic sizes, so as to achieve homogeneous emulsification and dispersion.
Its shear rate γ can be approximated by the following formula: γ = (π * D * N) / δ, where D is the rotor diameter, N is the rotor speed, and δ is the gap between the rotor and the stator. This formula shows that the shear rate is directly proportional to the rotor diameter and speed, and inversely proportional to the clearance size.
Main measurement and evaluation methods
The evaluation of the treatment effect of high-shear emulsifiers usually relies on the analysis of the physical properties of the final product. Commonly used measurement methods include: using a laser particle size analyzer to measure the size and distribution of dispersed phase droplets or solid particles, which is a direct indicator for evaluating the dispersion effect; The viscosity of the system before and after treatment was monitored by a viscometer. Observe or accelerate the testing of the stability of dispersion systems, such as by centrifugal sedimentation, resting stratification time, or using multiple light scatterometers to analyze their storage stability; For emulsions, their conductivity is sometimes measured to determine the type of emulsion.
Performance Factors
The treatment effect of the equipment is affected by multiple factors. In terms of equipment parameters, the structural design of the rotor and stator, tooth shape, clearance size, and linear speed of the rotor are the key. In the process parameters, the processing time, temperature control, and feeding sequence and speed of the material need to be considered. The material properties themselves, such as the interfacial tension between the two phases, the viscosity of the continuous phase, the volume fraction of the dispersed phase, and the need to add appropriate emulsifiers or dispersants, also have a significant impact on the final result. These factors need to be comprehensively optimized in practice.
Applications
High shear emulsification dispersers are widely used in several industrial fields. In the food industry, it is used in the production of sauces, condiments, dairy products and beverages to give them a delicate and stable taste. In the cosmetics and daily chemical industries, it is used to prepare creams, lotions, shampoos and toothpastes to ensure uniform product textures. In the chemical field, it is used in the production of coatings, inks, adhesives, pesticide emulsions and nanomaterial dispersion, which is essential for the uniformity and stability of product performance. In the field of biotechnology, it is also used for cell disruption and extraction and pretreatment of fermentation products.
Equipment selection considerations
Selection is a process that requires comprehensive trade-offs. First, the process objectives need to be defined, such as the final desired particle size range, throughput and material properties. Choose laboratory, pilot or industrial production equipment according to the throughput. Pay attention to the core parameters of the equipment, including motor power, speed range, whether the rotor stator material meets the requirements of corrosion or wear resistance, and whether its structure is easy to clean. Consider whether the equipment is scalable, such as whether it can be used with different working heads to accommodate multiple processes, and whether it has functions such as vacuum degassing or in-line cycling. It is recommended to conduct process tests with actual materials whenever possible before finalizing to verify the suitability of the equipment for a particular process.