Investigating Agglomeration Behaviors in High Temperature Gas–Solid Fluidized Beds with Liquid Injection

Abstract

An induction heating fluidized bed with liquid injection was designed to mimic the exothermic process of particles in industrial olefin polymerization fluidized beds. The effects of liquid injection flow rate on agglomeration behaviors were investigated through the characterization of agglomerate size and mass. Agglomeration mechanisms were proposed based on the experimental data of bed pressure drop, axial temperature distribution, and microscale visualization. Results have revealed that, with the increase of liquid injection flow rate, the agglomeration mechanism was controlled by the solid bridge force, the liquid bridge force, and the cooperative action of them, respectively. Wet agglomerates caused by the liquid bridge force induced local dead zones and provided a good environment for the occurrence of a hot spot and growth of solid bridge, and thus the formation of solid agglomerates. Besides, elevating the liquid injection position and increasing the induction heating power can widen the operation range of the liquid injection flow rate for fluidized bed reactors.

Study on the formation and evolution mechanism of dust deposition on solar photovoltaic panels

“…In rainy or snowy weather or when the temperature is low at night, the formation of a liquid bridge can cause dust particles to deposit on photovoltaic panels (Dormann and Schmid 2015). In addition, gravity and van der Waals forces may cause the deposition of dust particles on photovoltaic panels (Shi et al 2018). Our previous studies emphasised the dust particles deposited on photovoltaic panels as a result of the charged mechanism induced by a significant particle collision effect.…”

“…Previous research (Hanai et al 2011;Elminir et al 2006;Liu et al 2021aLiu et al ,2019aLiu et al ,2021bLu and Zhang 2018;Lu Lu-Yi et al 2008;Dormann and Schmid 2015;Shi et al 2018) has mainly analysed and discussed the factors influencing dust deposition characteristics. However, the dust deposition process is a complex phenomenon that is influenced by the coupled effects of gravity, buoyancy, van der Waals, drag, contact, electrostatic, and liquid bridge forces.…”

Distinguishing Liquid Transport Patterns during the Fluidization of Wet Particles with Bed Expansion Behaviors

“…It has been reported that the fluidization patterns of Geldart group B particles may transfer toward group A and finally to group C with continuous injection of liquid. − Specifically, group B particles were observed to expand homogeneously with liquid injection, exhibiting a typical feature of group A particles . As the liquid amount continues to increase, particle agglomeration takes place .…”

“…6 Similar results have been extensively reported. 7,8 The abovementioned trend is caused by the combined effect of the liquid bridge force and gas−solid drag force. 9 In view of the whole bed, the drag force tends to fluidize the particles, whereas the liquid bridge force is prone to bond the particles together, maintaining the bed in a stable manner.…”

Experimental and Modeling Investigation of Liquid-Induced Agglomeration in a Gas–Solid Fluidized Bed with Liquid Spray

“…However, the acquisition of aggregation kernel and breakage kernel is difficult because they are different under different conditions. 25 Thus, it is hard to investigate the process of liquid-induced agglomeration through the discrete element method or the population balance method when simulating a large-scale reactor or lacking appropriate kernel functions. In addition, no quantitative characterization of agglomeration rates, mass fraction of agglomerates, and particle size distribution has been carried out; meanwhile, most of them lack experimental validation.…”