GVSPM image reconstruction for capacitance CT images of particles in a vertical pipe and comparison with the conventional method

A new reconstruction method called generalized vector sampled pattern matching (GVSPM) was applied to the image reconstruction of an electrical capacitance computed tomography in freely falling particles in a vertical pipe. This new method is able to achieve stable convergence without the use of an empirical value. Experiments were carried out using three particle types with various electric charges and four particle flow rates to measure the capacitance of a pipe cross section. The three particle types were polyethylene pellets (PP), silica particles (SP) and polyvinyl chloride (PVC). Four particle flow rate settings were used resulting in a volume flow rate ranging from 3.08 × 10 −5 to 1.04 × 10 −3 m 3 s −1 . The GVSPM method is compared with conventional methods in terms of volume fraction, residual capacitance and correlation capacitance. Overall, the GVSPM method proved superior to conventional methods in the case of polyethylene pellets with relatively low electric charge. GVSPM achieves accurate reconstruction by using an objective function that is calculated as the inner product calculation between the experimental capacitance and the reconstructed image capacitance.