Investigations on Foam Detection Utilizing Ultra-Broadband Millimeter Wave FMCW Radar

Abstract

Foaming impairs the efficiency in several processes of the chemical industry. An early foam detection is advantageous to solve this problem. In this work we investigate the detection of foam by means of radar distance measurements utilizing a low noise 80 GHz FMCW radar with 25 GHz bandwidth. Two foaming solutions with several majority sizes of the air inclusions are used. First, a water butanol solution creates very fine foam. The foam surface is the only measurable reflection. However, it can be distingushed from a refelction at a liquid surface by means of the amplitude. Secondly, a water tenside solution creates fine to coarse foam. The foam surface as well as the liquid surface underneath exhibit a measurable reflection. The finer the foam is, the stronger the reflection at the foam surface and the weaker the reflection at the liquid surface is. Thus, the detection of foam by means of millimeter wave radar measurements is possible.