Ultrasonic waves have become a research hotspot in the world because of their mass production, heat transfer, and chemical reactions. In particular, the U.S., UK, France, and the unique role, as well as the development and popularity of ultrasonic power devices, gradually increase Japan and Russia. Some countries have made some progress in industrialization. The development of science and technology in our country ultrasonic probe homogenizer has become a new cross-disciplinary subject - sonochemistry. Its development has also done a lot of work on the theory and application of workers.
The so-called ultrasound generally refers to sound waves in the frequency range of 20-10 MHz, and its application power in the chemical field mainly comes from ultrasonic cavitation. With strong shock waves and micro jets with speeds higher than 100 m/s, high gradient shearing of shock waves and micro jets can produce hydroxyl radicals in aqueous solution. The corresponding physical and chemical effects are mainly mechanical (acoustic and shock waves). , micro-jets, etc., thermal effects (local high-temperature high-pressure, overall temperature rise), light effects (sonoluminescence) and activation effects (hydroxy radicals generated in aqueous solution), the four effects are not isolated, but interact, promote and accelerate Reaction process.
This article reviews the main applications of ultrasound in the field of chemical engineering in recent years in order to promote the research and application of ultrasonic technology in engineering.
Ultrasonic cleaning is one of the main applications of ultrasonics. Compared with other cleaning methods, ultrasonic cleaning has high efficiency, good quality, and can clean dirt in complex parts, deep holes, blind holes, and slits, and is easy to implement cleaning automation. . At present, ultrasonic cleaning machine manufacturers have grown from several in the early 1990s to several hundred now. With the further development of China's national economy, it will certainly become an indispensable technological tool for many industries, medical care, environmental protection and other departments.
The operating frequency of the ultrasonic cleaning machine is roughly divided into three frequency bands depending on the object to be cleaned: low frequency ultrasonic cleaning (20-50 kHz), high frequency ultrasonic cleaning (50-200 kHz) and megasonic ultrasonic Ultrasonic Plastic Welder cleaning (700 k-1 MHz or more). The low-frequency ultrasonic cleaning is suitable for the surface of large parts or where the dirt and the surface of the cleaning member have high bonding strength. The low frequency of the frequency, the cavitation intensity is high, it is easy to erode the surface of the cleaning part, it is not suitable to clean the part with high surface smoothness, and the cavitation noise is big. The frequency of about 40 kHz, at the same sound intensity, produces more cavitation bubbles than when the frequency is 20 kHz. The penetrating power is strong, but the cavitation intensity is low. Clean the surface with complex shapes or blind holes and clean the workpiece. Parts with weak adhesion between the dirt and the surface to be cleaned and less cavitation noise. High-frequency ultrasonic cleaning is suitable for fine-cleaning of microelectronic components such as disks, actuators, read/write heads, liquid crystal glass, flat panel displays, micro-components, and polished metal parts. These cleaning objects are required to be protected from cavitation during the cleaning process and to be able to wash away micron-sized contaminants.