Measurement and modeling of solids flow behaviors in an aerated standpipe and inclined pipe of circulating fluidized bed full-loop system

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 37 mm, 54 mm and 75 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. • Tracer accurately measured solids flow in an aerated standpipe and inclined pipe. • The method can determine the solids flow pattern via selecting a suitable tracer. • The constructed model can predict solids flow in the presence of aeration gas. • The model can predict the effect of pressure gradient on the solids flow. • Effects of pressure gradient can be counteracted by controlling aeration gas flow.