Spouting Characteristics of Wet Particles in a Conical-Cylindrical Spouted Bed

Abstract

Spout characteristics, such as flow pattern, minimum spouting velocity, and maximum spoutable bed height, are investigated in a wet conical-cylindrical spouted bed. Water and glass beads (Geldart D type) are adopted as the liquid and solid phases, respectively. The evolution of flow pattern of a wet spouted bed is captured by a CCD camera. The experimental results indicate that the minimum spouting velocity decreases when increasing the liquid saturation. The increase of initial bed height, particle size, or spout nozzle size leads to increased minimum spouting velocities. A correlation is formulated based on the experiments results for the prediction of minimum spouting velocities of wet spouted beds. Moreover, it is found that the maximum spoutable bed height H max decreases as particle size or spout nozzle diameter increases. However, H max is almost constant, approximately 1.5 times higher than that of its corresponding dry spouted bed, when increasing the liquid saturation.

Characteristics of Geladart-B Particles in Fluidized Beds

“…As long as the superficial gas velocity exceed the minimum fluidization velocity, bed pressure stop arising but fall slowly. And the gas velocity corresponding to this turning point is exactly the minimum fluidization velocity in Table 2 [9]. Fig.…”

“…The air stream comes from the bottom of the fluidized bed, which is covered with the porous air distributor. When the gas passes through the particles, there exists drag forces and buoyancy forces [9]. If the velocity of the air reaches the minimum fluidized velocity of solids, particles start to flow and few tiny bubbles appear (Q=0.325m3/h).…”

Fluidization dynamics of cohesive Geldart B particles. Part II: Pressure fluctuation analysis

“…Unlike the dominant frequency that corresponds to the highest intensity of the PSD, f a accounts for all the waves based on their amplitudes, and is therefore very representative for characterizing the PSD with broad frequency band and multiple peaks. Its definition is as follows: (5) where P(f) is the intensity of PSD at the frequency of f; f min and f max are the minimum and maximum frequency of PSD.…”

“…Nevertheless, due to the limitation of measurement methods, most of these researches focused on global and visual phenomenon, i.e. minimum fluidization [4,5], defluidization pattern [6], bubble behaviors [7,8], particle mixing [9] etc. Recently, lots of researchers made efforts for more insight into the fluidization dynamics of cohesive particles with the aid of advanced measurement approaches.…”

Liquid transport rates during binary collisions of unequally-sized particles

“…[1]). It is well known that particle-size polydispersity and shape significantly influence the transport of mass and liquid in a fluidized bed [1,2] and spouted beds system [3]. Therefore, a better understanding of these systems (i.e., that involving particles of different sizes) helps to improve the control of many engineering applications, including fluidization, mixing, agglomeration, or coating.…”