Analysis of Range-Doppler Radar Echos for Condition Monitoring in Industrial Processes

A large variety of processes are applied in industry, such as in the chemical and food sectors. Among those, the storage and processing of liquids inside tanks as well as chemical, biological and other reactors is of particular interest. In this contribution, methods for condition monitoring (CM) in applications of this type are presented and evaluated. The measurement capabilities of radar systems, which are already used for determining the filling level, are extended towards a characterization of the liquid’s surface in order to distinguish between different operating conditions for CM. The proposed approach is to assess movements of the surface by means of range-Doppler radar measurements and to derive quantitative features therefrom. With respect to process conditions (PCs) like heating, boiling and changing the filling level of the liquid, the potential of this approach for CM has been experimentally evaluated. Measurements have been performed using a frequency-modulated continuous-wave (FMCW) Doppler radar system operating from 68 to 92 GHz. It is shown that the selected PCs can be reliably distinguished based on the temporal behaviour of their range-Doppler maps and of the parameters extracted therefrom, such as the Doppler velocity at the peak amplitude and the peak-to-average power ratio.