Application of electrical resistance tomography on liquid-solid two-phase flow characterization in an LSCFB riser

The application of liquid-solid circulating fluidized beds (LSCFB) is steadily increasing in the chemical, biochemical and other industries. Electrical resistance tomography (ERT) as an imaging technique was employed for the study of flow parameters such as phase holdup, velocity distribution of individual phases in LSCFB. ERT is a non-invasive technique based on conductivity measurement of the continuous phase, which also provides color-coded cross-sectional view of phases with a frequency of up to 250 images per second. The local conductivity measured by a number of electrodes located at the periphery of the plane was then further converted into a local phase concentration distribution based on Maxwell's relation. Local solids holdup also measured by using optical fibre probe to compare and verify the result obtained by ERT. By cross-correlation between the data obtained from a pair of planes of ERT, one upstream and one downstream, the phase propagation velocity was determined. Water was used as the continuous and conductive phase and glass beads and lava rocks (LR) of 500 μm sizes were used as the solid and non-conductive phase in this investigation. Radial non-uniformity of phase holdups was observed at different superficial liquid velocities. Solids holdup was higher in regions close to the wall and low in the central area. Such non-uniformity in phase holdup decreased with increasing liquid velocity. Both solids holdup and radial non-uniformity increased with superficial solids velocity. The solids propagation velocity increased in the central region under different superficial liquid velocities. Good agreement was observed between the data obtained from the two methods. Crown