Ultrasonic defoaming and debbubling in food processing and other applications

Foam is a multiphase medium generally produced as an unwanted by-product in many industrial processes. Conventional defoaming methods use mechanical, thermal, electrical, or chemical effects. Chemical methods, using antifoam agents, are the most effective, but they also contaminate the process. A better method is the use of airborne ultrasonic radiation, which offers a clean means of breaking foams without making contact with the liquid. This chapter deals with the mechanisms and effects of ultrasonic waves for use in foam destruction and reviews the ultrasonic defoaming systems currently in use. A section about the application of ultrasonic radiation for debubbling liquid coating layers is also included.