The principle and structure of ultrasonic homogenizer
Core Tip: Ultrasonic homogenization is achieved using sound waves and ultrasonic waves that alternately compress and inflate when encountering objects. When the material is under the action of ultrasonic waves, the material and liquid Ultrasonic Extraction Machine will be expanded by the bubble when it is in the expansion half cycle; when it is in the compression half cycle, the bubble will shrink when the pressure changes
Ultrasonic homogenization is based on the principle of using sound waves and ultrasonic waves to rapidly alternately compress and expand when encountering objects. When the material is under the action of ultrasonic waves, when the material is in the expansion half cycle, the material liquid is expanded by the air bubble; when it is in the compression half cycle, the air bubble shrinks when the pressure changes greatly and the pressure is lower than the low pressure. At that time, the compressed air bubbles collapse sharply, and a "hole" phenomenon occurs in the feed liquid. This phenomenon disappears with the pressure change and the unbalance of the external pressure. At the moment when the "hole" disappears, the liquid The surroundings cause very large pressure and temperature increase, and play a very complicated and powerful mechanical stirring effect to achieve the purpose of homogenization. At the same time, at the interface where the "cavity" has a density difference, the ultrasonic wave also reflects and produces intense stirring. According to this principle, the ultrasonic homogenizer is a device that puts an ultrasonic generator at a frequency of 20 to 25 kHz into the feed liquid or uses a device that allows the feed liquid to have a high-speed flow characteristic, and uses ultrasonic stirring in the feed liquid to make the feed liquid achieve Homogeneous.
The ultrasonic homogenizer is divided into mechanical, magnetron-oscillatory, and piezoelectric crystal oscillator types in the form of ultrasonic generators.
1. Mechanical ultrasonic homogenizer
The mechanical ultrasonic homogenizer mainly consists of a nozzle and a reed. The principle and structure of the generator are shown in Figs. 13-15.
The reed is in front of the nozzle. It is a wedge-shaped metal piece sandwiched between two or more nodes. When the feed liquid is sprayed onto the reed via the nozzle at a high speed with a pump pressure of 0.4 to 1.0 MPa, the reed emits a vibration at a frequency of 18 to 30 MHz. The ultrasonic wave is immediately transmitted to the feed liquid, so that the feed liquid is in a state of intense agitation, the large particles in the feed liquid are disintegrated, the feed liquid is homogenized, and the homogenized feed liquid is discharged from the outlet.
2. Magneto-oscillating homogenizer
The ultrasonic generator of the magnetron oscillating homogenizer Ultrasonic Sprayer oscillates at a frequency of several tens of kilohertz by using a magnetic helium such as nickel grain iron so that the material liquid can be homogenized under strong stirring.
3. Piezoelectric oscillator type homogenizer
Piezoelectric crystal oscillating homogenizers are made of osmium ferrite or crystal oscillators as ultrasonic generators, so that the oscillating frequency is up to several tens of kilohertz, and the material liquid is strongly oscillated to achieve homogeneity.