Experimental studies on the solids holdup of a high-flux circulating fluidized bed (HFCFB) at an operating pressure up to 0.5 MPa were carried out. The effects of operating pressure, solids mass flux and superficial gas velocity on the solids holdup distribution were systematically tested. It was found that the solids holdup at elevated pressure increases with increasing solids mass flux but decreases with increasing superficial gas velocity, which is similar to the trends at atmospheric condition. As a result, the condition of a high-density circulating fluidized bed (HDCFB), i.e., solids holdup in everywhere of the riser is larger than 10 %) is easier to be achieved at elevated pressure than in a HDCFB operated at atmospheric pressure. In the current work, the condition of a full HDCFB with Geldart group B particles has been achieved successfully at 0.5 MPa.

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Experiments of gas-solid suspension were carried out in a high-flux circulating fluidization bed with the solid mass flux up to 536 kg/(m2·s). Differential pressure fluctuation time series were obtained at different locations in the riser. Shannon entropy increment rate analysis was developed to identify the flow pattern and transformation and characterize the dynamic behavior. Effect of superficial gas velocity on the Shannon entropy increment rate was examined under high solid mass flux. It was demonstrated that a circulating fluidization bed at high solid mass flux was a deterministic chaos system and the sensitivity of the system's chaotic characteristic to operating parameters at different flow regimes was different. Shannon entropies increment rate of different flow regimes were distinct. Shannon entropy increment rate analysis method results in high degree of recognition for flow pattern and transformation.