P2I-7 On a New Sensing Strategy Using a Combination of Ultrasonic and Photoacoustic Techniques

In the process industry there is a need for development of new or improved in-line sensor techniques determining bulk properties of a suspension or different physical properties of the suspended particles. In this study we present a sensing strategy where both acoustical and photoacoustical measurement techniques are integrated and applied to aqueous fibre suspensions. The two measurement techniques were tested experimentally in a custom made measurement cell using Nylon 66 fibres suspended in distilled and degassed water to mass fractions of 0.12% and 0.25%. The result shows two different behaviors. The attenuation in the transducer generated pulse is proportional to mass fraction in the suspension. And the photoacoustical signal is sensitive to the amount of scatterers, i.e fibres, in the suspension. Further work is required to determine this relation. If the relation is established, the combination of these techniques has the potential to give the mass fraction as well as the particle number density in an aqueous fibre suspension