Cleaning of closed production lines is a crucial process in the food industry. Inline fittings such as pipes, valves or pumps are often cleaned by oversized CIP procedures, which are designed according to the worst-case scenario because there is a lack of sensors to monitor the cleaning progress. To overcome this issue, a novel sensor system was developed at Fraunhofer IVV based on the inverted piezo electrical effect. The sensor uses quartz crystals to detect soiling layers on the surface of the machinery. Therefore, a network analyser induces an AC voltage into the quartz, and in return measures the resulting resonance parameters, such as frequency and attenuation. The resonance of the quartz differs with its mass. Hence, any adhering soiling layer influences the measured signal. To implement this sensor principle in a CIP process it has to meet specific requirements. The main issue is that quartz crystals are very thin and vulnerable because they need to oscillate freely. Therefore, a concept to equalize the pressure on both sides of the quartz was developed and tested. This allows the use of the sensor system also for applications with high operating pressure during production without breaking. First tests with the sensor were performed in a flow channel test rig. The quartz was thereby coated with a model soiling and afterwards cleaned in the channel. As a reference, an established optical sensor monitored the cleaning process. Starch, custard and tomato paste were used as model soiling. The tests showed that the sensor is able to detect the soiling removal from its surface and that the signal fits with the optical sensor data. Furthermore, it was possible to observe an influence of the operating parameters, such as fluid temperature or cleaning agent on the sensor signal, which needs to be compensated by calibration and smart data processing.<br/>

Monitoring soiling removal in food processing lines

ACS Fall 2020 Virtual Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.