Measurement of Three-Phase Holdup Distribution in Gas–Liquid–Solid Fluidized Bed Based on ERT/TMR-EMT

The measurement of three-phase holdup distributions in the gas–liquid–solid fluidized bed has guiding significance for the fluidized bed's characterization, design, and optimization. Aimed at the measurement of three-phase holdup distribution simultaneously, an image reconstruction method for electrical resistance tomography and electromagnetic tomography based on tunnel magnetoresistance (ERT/TMR-EMT) dual-modality system is proposed. The distributions of equivalent conductivity and equivalent permeability are reconstructed by the D-bar algorithm based on ERT and TMR-EMT, respectively. Then, the three-phase holdup distribution is reconstructed through equivalent media theory. From the results of the reconstructed image and three-phase average holdup in simulation, the holdup variations of the gas, liquid, and solid are principally consistent with the phantom sets. From the measurement results of the dynamic experiments, clusters with high solid holdup and bubbles with high gas holdup can be accurately reflected and the variation of three-phase holdup distribution and average holdup can correctly reflect changes in experimental states in the fluidized bed.