Electrical resistance tomography using high and low conductivity calibration

This paper describes a combined conductance ring and electrical resistance tomography (ERT) sensor for measuring the fraction of non-conductive phases, solid and gas phases, in the gas-liquid-solid circulating fluidized bed (GLSCFB). The conductivities of liquid and packed solid phases can be determined by the conductance ring sensor, which provides the information on the conductivity range of liquid-solid mixture. Therefore, the ERT sensor can be calibrated with both the high and low conductivity phases of known conductivities. Consequently, the pixel values of ERT reconstructed images can be normalized by the low and high conductivities, thus providing better estimation to the local phase conductivity and fraction. The dynamic experiments have been performed to validate the proposed sensor and method, in which the tap water and Al₂O₃ particles are employed as the liquid and solid phases, respectively. Experimental results show that the proposed sensor and method can be applied to investigate the volume fraction of solid and liquid phases in a GLSCFB.