A Model-Based Analysis of Capacitive Flow Metering for Pneumatic Conveying Systems: A Comparison between Calibration-Based and Tomographic Approaches
Sprache des Titels:
Pneumatic conveying is a standard transportation technique for bulk materials in various industrial ?elds. Flow metering is crucial for the ef?cient and reliable operation of such systems and for process control. Capacitive measurement systems are often proposed for this application. In this method, electrodes are placed on the conveyor systems transport line and capacitive signals are sensed. The design of the sensor with regard to the arrangement and the number of electrodes as well as the evaluation of the capacitive sensor signals can be divided into two categories. Calibration-based ?ow meters use regression methods for signal processing, which are parametrized from calibration measurements on test rigs. Their performance is limited by the extend of the calibration measurements. Electrical capacitance tomography based ?ow meters use model-based signal processing techniques to obtain estimates about the spatial material distribution within the sensor. In contrast to their calibration-based counterparts, this approach requires more effort with respect to modeling and instrumentation, as typically a larger number of measurement signals has to be acquired. In this work we present a comparative analysis of the two approaches, which is based on measurement experiments and a holistic system model for ?ow metering. For the model-based analysis Monte Carlo simulations are conducted, where randomly generated pneumatic conveying ?ow patterns are simulated to analyze the sensor and algorithm behavior. The results demonstrate the potential bene?t of electrical capacitance tomography based ?ow meters over a calibration-based instrument design.