Evaluation of a concept for density measurement ofsolid particle flows in pneumatic conveying systems with microwaves (8–12 GHz)

[摘要] This paper presents a novel density measuring concept for gas/coal particlecompositions in pneumatic conveying systems. The proposed monitoring systemuses horn antennas to perform complex electromagnetic transmittancemeasurements through the cross section of the conveying tube. The phase ofthe complex transmittance gives information about the effective permittivity,which is related to the mean volume fraction of the coal. Electromagneticfield simulations have been performed for the evaluation of the concept andthe performance of the designed setup. A test stand for measurements on coaldust under reproducible conditions and with well-defined particleconcentrations has been developed and implemented. The test tube has adiameter of 200 mm and a length of 400 mm. Coal particles with a diameterbetween 20 μm and 100 μm have been dispersed byinjecting nitrogen gas inside the test tube. Complex transmissionmeasurements are performed in the implemented setup with a calibrated vectornetwork analyzer within a frequency range of 8–12 GHz. Results of theconceptual evaluation by measurements with different concentrations of coalparticles are presented and discussed.

[学科分类] 电子、光学、磁材料