In this study, the optimization of a gas–solid fluidized bed structure under oscillating conditions is carried out, and the traditional equal-diameter structure is improved to a variable-diameter structure. In this paper, a 300 mm diameter equal-diameter fluidized bed is taken as the benchmark model, and the research team uses numerical simulation to analyze the changing law of bubble size and the percentage of non-fluidized area. It is found that under the condition of the same gas volume, the “cone-contraction” fluidized bed with variable-diameter structure can reduce the bubble size by about 25% and the percentage of non-fluidized area by about 11%. The effects of the specific operating parameters are as follows: the operation of increasing the gas volume will lead to an increase in bubble size but will lead to a decrease in the percentage of non-fluidized area; the increase in the initial bed height will simultaneously increase the bubble size and the percentage of non-fluidized area; the increase in the amplitude of the oscillation will lead to an increase and then a decrease in the bubble size, and will lead to a continuous expansion of the percentage of non-fluidized area; and the change in the oscillation period will not have a significant effect on the two. A comparison of the experimental data shows that the overall performance of the variable-diameter fluidized bed is better than that of the equal-diameter fluidized bed, as shown in the following: the bubble size is reduced by 24~32%, and the percentage of non-fluidized area is reduced by 6~12%. This study provides an effective direction for the structural optimization of fluidized beds.

To address the effect of a ship’s rolling on the fluidization quality of fluidized beds, in this study, a simulation of a rolling fluidized bed with longitudinal internal members added (R-FBLIM) was carried out and compared with that of a rolling fluidized bed without internal members added (R-FBWIM). The transient motion, as well as the behavioral characteristics of the bubbles within the R-FBLIM, was analyzed; the variation patterns of the number of bubbles, as well as the equivalent diameter of the bubbles, were compared for different apparent gas velocities, oscillation periods, and amplitudes; and the mechanism of the action of the longitudinal internal members was investigated. The results show that the structural design of the longitudinal internal members can effectively improve the gas–solid fluidization quality of the rolling fluidized bed. The horizontal support plate and the cap hole structure can effectively break the air bubbles, the cap hole structure promotes the radial mixing of the gas–solid fluid, and the internal and outer rings of the curved surface plate roll in rows, which inhibit the aggregation behavior of the gas–solid fluid to the two sides of the oscillating planes, respectively, by cooperating with the cap hole structure. Compared with R-FBWIM, the gas–solid phase within R-FBLIM is more spatially distributed, with the number of bubbles increasing by about 2–4 times and the mean diameter decreasing by about 50–60%. The number of bubbles increases with the gas velocity but decreases with the rolling amplitude; the mean diameter decreases with the gas velocity but responds less to the rolling amplitude change.

To improve the operational stability and mass transfer performance of fluidized bed reactors under dynamic conditions, this study examines radial particle velocity distributions at different bed cross-sections using a dual-probe measurement method across a range of rocking frequencies and superficial gas velocities. The analysis identifies the dominant influence of additional inertial forces generated by rocking motion, including the Euler force and Coriolis force, in determining the time-averaged flow structure, leading to the development of a spatiotemporally averaged flow field model and clarification of the interaction mechanisms between these forces. Results indicate that the flow field exhibits two representative macroscopic patterns governed by the interplay between inertial forcing and particle response characteristics: at low frequencies, the slowly varying Euler force combines with gravity to produce a coherent large-scale single-circulation structure, whose stability is sustained under higher gas velocities due to reduced internal energy dissipation associated with stronger drag; at high frequencies, the Coriolis force promotes structural division while the rapidly oscillating Euler force introduces disturbances, resulting in the formation and persistence of double or multi-circulation flow structures under their combined action.