Ultrasound enables exact measurement of wastewater quantities
If several communities share a sewage treatment plant, the costs are usually broken down based on the amount of wastewater discharged. Who likes to pay for the dirt of others. At the German Fraunhofer Institute for Biomedical Engineering (IBMT) in St. Ingbert, researchers have now developed an ultrasonic measuring device with which such amounts of waste water can be measured very precisely and disputes can be avoided. Conventional devices for flow measurement usually have one major disadvantage: they require a specific flow profile – a certain velocity distribution – in the pipe. According to information from the IBMT, the inlet and outlet sections required to form such a profile are often not available in practice. The result is measurement errors. Conventional sensors also protrude into the flow and thus falsify the results.
The new ultrasonic flow meter, on the other hand, constantly determines the flow conditions. This enables precise flow measurement for any profile. The device emits short ultrasonic signals at periodic intervals, which are reflected by dirt particles or fine air bubbles.
"With the help of the echo signals received, the change in position of the individual particles can be tracked and the flow velocities at different depths of the liquid can be determined," explained Margit Barth from the IBMT. It is also possible to determine flow distributions in mixing, reaction, separation and settling processes.