Recurrence plots and recurrence quantification were used to analyze pressure fluctuation signals in a dense gas-solid fluidized bed. Parameters including determinism (Qdet), average diagonal line length (Ql), and laminarity(QLAM) were determined from the recurrence plot. Comparative analysis of the flow images and parameters was performed. The bubbles become larger, and the chaotic characteristic in the fluidized bed strengthens with increasing gas velocity. The biomass particles are preferentially blown to the upper layer and mixed with quartz sand at high gas speed. Large bubbles in the fluidized the bed can be easily broken by biomass particles with increasing biomass concentration. The presence and movement of large cylindrical biomass lead to decreased bubble size, uniform energy, and reduced Qdet, Ql and Qlam. The minimum fluidization velocity of the mixed flow of quartz sand and biomass is 0.5m/s. The pressure drop increases with increasing bed height and is not related to biomass concentration.
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