Process monitoring using ultrasonic sensor systems.

Continuous in-line measurement of substance concentration in liquid mixtures is valuable in improving industrial processes in terms of material properties, energy efficiency and process safety. Ultrasonic sensor systems meet the practical requirements of a chemical sensor quite well. Currently ultrasonic sensor systems are widely used as acoustic chemical sensors to measure concentration of selected substances or to monitor the course of polymerisation, crystallisation or fermentation processes. Useable acoustic properties for the characterisation of liquid mixtures are sound velocity, sound absorption and acoustic impedance. This contribution will give a short overview of the state of the art and several trends for the use of ultrasonic sensor systems in process applications. Novel investigations show the very promising possibility to analyse liquid multi-phase mixtures like suspensions, emulsions and dispersions.