Abstract: The actual value of the transport disengaging height (TDH) in a gas-solid fluidized bed is drastically different from the value that is anticipated. One of the primary reasons for this difference is that the electrostatic impact is ignored. Because it is impossible to quantitatively regulate the charge that is carried by the particles using the experimental procedures that are now in use, it is also difficult to analyze the impact that electrostatic effects have on TDH using experimental methodological approaches. In this work, the CFD-DEM numerical simulation method is used to study the particle entrainment and TDH problems in a three-dimensional fluidized bed. They combine the average height of particles in the free space, the average solid phase concentration, and the longitudinal particle velocity. This is done while taking into consideration the electrostatic effects that occur between particles. The influence and mechanism of the electrostatic force on the entrainment rate and TDH are derived, which provides a theoretical basis for the establishment of a method that is more accurate in forecasting TDH. Specifically, the findings indicate that the electrostatic impact between particles has the potential to impede the entrainment of particles and to decrease the entrainment rate. It is possible for the electrostatic force between particles to increase the average particle height and the longitudinal velocity of particles in free space, which ultimately results in an increase in the TDH when the charge that the particles carry is relatively low. Nevertheless, when the charge that the particles carry is substantial, the electrostatic attraction between the particles is likely to produce particle agglomeration. This, in turn, will reduce the concentration of the solid phase in the free space and hinder the entrainment of the particles, which will result in a decrease in the TDH.

Key words: electrostatic effect, gas-soild fluidized bed, transport disengaging height, particle entrainment, CFD-DEM method

摘要： 忽略静电效应是气固流化床中沉降分离高度实际值与预测值之间误差产生的重要原因。由于难以定量控制颗粒带电量，因此很难通过实验方法研究静电效应对沉降分离高度造成的影响。本工作考虑颗粒间的静电效应，采用CFD-DEM数值模拟方法，对三维流化床中的颗粒夹带和沉降分离高度问题进行研究。结果表明，颗粒之间的静电效应会抑制颗粒夹带，降低夹带率；颗粒带电量较小时，颗粒间静电力可以增大平均颗粒高度和自由空域中颗粒纵向速度，增加了沉降分离高度；颗粒带电量较大时，颗粒间的静电吸引力容易造成颗粒团聚，降低了自由空域中的颗粒浓度，抑制了颗粒夹带，减小了沉降分离高度。

关键词: 静电效应, 气固流化床, 沉降分离高度, 颗粒夹带, CFD-DEM方法