To control solids circulation and optimize design and operating parameters in a circulating fluidized bed full-loop system, measurement and modeling of solids flow behaviors in an aerated standpipe and inclined pipe were conducted. Different aeration gas flows were injected at the inclined pipe, which was equipped with different orifice sizes of 37Â mm, 54Â mm and 75Â mm, for regulating solids flow rates. The magnetic tracer-tracking method, which only needs to inject one small magnetic tracer for each measurement to follow the main solids flow, was successfully demonstrated for measuring sand particles’ real-time discharge rates, with good accuracy and no calibration requirement. A mathematical model was constructed to predict solids discharge rates and investigate the adverse effect of the pressure gradient in the standpipe bed in a full loop fluidized bed system. The optimization of the solids-return and circulation unit could therefore be achieved with the tools developed in this study.
The work was carried out within the national Biokraft 2023 project (No P2022-00586) and the EU BioFlexGen project (No 101037085). Funding from the Swedish Energy Agency and the EU Horizon 2020, and the experimental work of Håkan Jonsson and Kim Thomas are gratefully acknowledged.