A CONDUCTANCE PROBE FOR MEASURING LIQUID FRACTION IN PIPES AND PACKED-BEDS

The performance of ring electrodes measuring the conductance of gas liquid mixtures in pipes and packed beds is studied experimentally and theoretically. With relatively closely spaced pairs of rings, one can detect liquid segregation, i.e. stratified and annular distribution, as well as a uniform liquid distribution if the mean liquid fraction is available. Conversely, reliable cross-sectionally-averaged holdup data can be obtained if the liquid distribution pattern is known. Measurements in packed beds and pipes are qualitatively very similar. Existing theoretical expressions are employed to interpret the conductance measurements. Moreover, a new analytical solution for an annular liquid distribution is presented, which is particularly helpful in assessing the spatial probe sensitivity in the axial direction. The latter is found to be quite satisfactory. In general, agreement between the data and theoretical predictions is fair to excellent, providing the necessary confidence for practical applications. Two successful applications of the technique to packed beds are reported.