Ultrasonic sensor for the detection of fouling in UHT processing plants

Abstract Analysis of an ultrasonic signal in the time domain was investigated as a means of detecting and measuring the thickness of fouling deposits in the pipework of continuous high-temperature processing plants. A prototype sensor was developed and used for experimental trials both off- and on-line. It was able to detect the presence of deposits with a minimum thickness of 0.1 mm and measure the thickness of films over the range 0.5 to 6.0 mm. The sensor was found to be sensitive to product temperature an compensation for this was implemented over the range 20–140°C. It was found to be immune to the effects of product flow rate from 0 to 25 litres/min and pressure over the range 0 to 3 bar.