Ultrasound detection techniques

摘要

A method for separating a liquid and in particular a liquid metal from heterogeneous constituents therein, comprises the steps of providing a passage for a flow of liquid containing heterogeneous constituents and directing ultrasound waves into the passage. The ultrasound waves are made to form standing waves in the liquid using a reflector and by tuning the frequency of the ultrasound waves. The standing waves cause extraneous particles in the liquid to coagulate at the nodes. The reflector is also designed to direct some of the ultrasound waves upwardly into the passage. The flow of the liquid metal through the passage and the ultrasound in the passage carry the coagulated particles into the slag on the surface of the liquid metal for removal. The ultrasound waves also cause cavitation effects which degas the liquid metal. An ultrasound particle detection device is also disclosed which includes a transmitting delay line, a receiving delay line and a reflector immersed in a liquid. The reflector reflects ultrasound from the transmitting delay line to a focal volume. The receiving delay line receives ultrasound reflected by extraneous particles in the focal volume allowing for their detection.