What is ultrasonic dispersion technology?
A phase as a particle state, the system dispersed in other phases is called the dispersion system, the particle is called the dispersion material or the dispersion phase, and the other phase into the medium is called the dispersion medium or continuous phase, this dispersion system can be divided into the following three types according to the size of the dispersion particle: macro (coarse) dispersion system, colloidal dispersion system, molecular dispersion system. Macroscopic dispersion system, dispersed particle diameter above 0.1 μm.
Generally, the dispersed phase of the dispersion system is gas, liquid, solid, and the dispersion medium can also be gas, liquid, solid, etc. When the dispersed phase is liquid, the most is emulsion or emulsion; When the corresponding dispersed phase is solid, it is more commonly called suspension; When the dispersed phase is a gas and the particle diameter is below 0.lμm, it is called foam colloid.
The most prominent and widely known effect of power ultrasound in liquids is the dispersion effect, and the dispersion effect of ultrasound in liquids mainly depends on the ultrasonic cavitation of liquids.
Two factors affecting the dispersion effect:
Ultrasonic impact force, if the dispersion tool used and the type of treatment liquid have been determined, the ultrasonic impact force is determined by the average pressure p of the treatment liquid, the liquid gap C and the temperature.
The ultrasonic radiation time, the flow rate of the treatment liquid is Q (cm3), the gap is c (cm), and the plate area of the relative direction is S (cm2), then the average time t required for the specific particles in the treatment liquid to pass through this space is: t = cS/Q
In order to improve the ultrasonic dispersion effect, it is necessary to control the average pressure p, gap c and ultrasonic radiation time t of the treatment liquid.
Ultrasonic dispersion does not require the use of emulsifiers, and in many cases ultrasonic emulsification can obtain particles below 1μm. The formation of this high-quality solution is mainly due to the formation of strong ultrasonic cavitation near the dispersion tool. The paraffin wax can be dispersed in water by ultrasonic without emulsifier, and the diameter of the dispersed particles can reach less than lμm.
Ultrasonic dispersion is usually characterized by small amplitude and large acceleration. For example, an acceleration with a frequency of 20kHz and an amplitude of 50μm is 80,000 times the acceleration of gravity. Locally, ultrasonic dispersion devices that can concentrate high power have been widely used in food, fuel, new materials, cosmetics, coatings and other fields.
Ultrasonic dispersion system is composed of ultrasonic vibration system, ultrasonic generator, ultrasonic dispersion tool and dispersion container:
1. Ultrasonic vibration system, in order to obtain high power, its resonance frequency is selected at about 15kHz~20KHz;
2 Ultrasonic generator (also known as ultrasonic power supply), its efficiency up to 90%, and small size, light weight, ultrasonic generator and resonance system composed of a frequency automatic tracking system;
3. Ultrasonic dispersion tool, made of titanium alloy or stainless steel, with good corrosion resistance; Vibration power transmission should be fast; Good acid corrosion resistance;
4. Dispersion container, when the ultrasonic generator output high-frequency voltage is added to the ultrasonic vibrator, the mechanical amplitude of the vibrator transformer is amplified under the action of the dispersion tool, and the strong dispersion treatment is carried out in the container.
The relationship between frequency and particle size:
The higher the frequency, the finer the scattered particles; The lower the frequency, the coarser the scattered particles;
From the situation of noise reduction, the noise is small when the frequency is high;
The power requirement is sufficient to generate cavitation conditions must be met.
25 Jul 2024
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