Particle–particle and particle–wall collisions in gas–solid fluidized beds lead to charge accumulation on particles. This work evaluated the effect of fluidization time on charge transfer and bipolar charging (charge separation) and their influence on hydrodynamic structures in a fluidized bed. Experiments were performed with glass beads and polyethylene particles in a glass column. The pressure fluctuations and net electrostatic charge of particles were measured during fluidization. Wavelet and short-time Fourier transforms were used to analyze pressure fluctuations. The results revealed that bipolar charging is the dominant tribocharging mechanism in a bed of glass beads. Bipolar charging in a bed of particles with a narrow size distribution does not affect either hydrodynamic structures or the transition velocity to the turbulent regime. A large difference between the work functions of the wall and particle in the bed of polyethylene particles leads to high charge transfer. Formation of a stagnant particle layer on the wall eventually causes the energy of macro-structures to increase to its maximum. At longer fluidization times, the macro-structural energy decreases and bubbles shrink until the electrostatic charge reaches the equilibrium level. These results well describe the effect of fluidization time on hydrodynamic structures.

气固流化床中的颗粒间碰撞和壁间碰撞导致电荷在颗粒上积累。这项工作评估了流化时间对电荷转移和双极性电荷（电荷分离）的影响，以及它们对流化床中流体力学结构的影响。用玻璃珠和聚乙烯颗粒在玻璃柱中进行实验。在流化过程中测量颗粒的压力波动和净静电荷。小波和短时傅立叶变换用于分析压力波动。结果表明，双极性充电是玻璃珠床中主要的摩擦充电机制。具有窄尺寸分布的粒子床中的双极带电既不会影响流体动力学结构，也不会影响到湍流状态的过渡速度。壁和聚乙烯颗粒床中颗粒的功函数之间的巨大差异导致高电荷转移。壁上停滞的颗粒层的形成最终导致宏观结构的能量增加到最大。在更长的流化时间下，宏观结构能降低，气泡缩小，直到静电荷达到平衡水平。这些结果很好地描述了流化时间对流体动力结构的影响。宏观结构能下降，气泡缩小，直到静电荷达到平衡水平。这些结果很好地描述了流化时间对流体动力结构的影响。宏观结构能下降，气泡缩小，直到静电荷达到平衡水平。这些结果很好地描述了流化时间对流体动力结构的影响。