Solids flow mapping in a gas–solid riser: Mean holdup and velocity fields

In this study, solids flow dynamics has been investigated in a 6 in. “cold-flow” circulating fluidized bed riser using non-invasive flow techniques. Gamma ray Computed Tomography (CT) has been used to measure the time-averaged cross-sectional solids holdup distribution. The time-averaged mean and fluctuating solids velocity fields have been quantified using the Computer Automated Radioactive Particle Tracking (CARPT) technique. Details of the experimental techniques, protocol of implementation and data analysis are discussed. The experimental studies examine operating conditions in fast fluidization and dilute phase transport regimes. Comparative and symbiotic analyses of the results obtained from CARPT and CT have been used to develop a coherent picture of the solids flow field. In addition, this work also demonstrates the power of CARPT and CT as flow mapping techniques in studying highly turbulent and opaque multiphase systems.