Distribution of large biomass particles in a sand‐biomass fluidized bed: Experiments and modeling

Abstract

The axial distribution of large biomass particles in bubbling fluidized beds comprised of sand and biomass is investigated in this study. The global and local pressure drop profiles are analyzed in mixtures fluidized at superficial gas velocities ranging from 0.2 to 1 m/s. In addition, the radioactive particle tracking technique is used to track the trajectory of a tracer mimicking the behavior of biomass particles in systems consisting of 2, 8, and 16% of biomass mass ratio. The effects of superficial gas velocity and the mixture composition on the mixing/segregation of the bed components are explored by analyzing the circulatory motion of the active tracer. Contrary to low fluidization velocity (U 5 0.36 m/s), biomass circulation and distribution are enhanced at U 5 0.64 m/s with increasing the load of biomass particles. The axial profile of volume fraction of biomass along the bed is modeled on the basis of the experimental findings.

Magnetic tracking of a fuel particle in a fluid-dynamically down-scaled fluidised bed

“…The validity of the fluid-dynamical scaling laws for fuel mixing was experimentally validated by Sette et al [23], using a laboratory-scale setup at ambient temperatures that resembled hot, large-scale conditions. In such down-scaled beds, the possibility to continuously track individual tracer particles is severely restricted due to: (i) the lack of direct visual access to the interior of the dense bed (as in any 3-dimensional fluidised bed unit); and (ii) the difficulty of applying tomographic methods (e.g., [41][42][43]) to beds that contain metallic powders (which are needed for fluid dynamic similarity, [44]). Therefore, in previous studies, tracer particles have been followed using discontinuous direct tracking (e.g., observations at or above the dense bed surface [23,24]).…”

“…Regarding experimental studies of solids mixing in non-scaled beds at ambient conditions, the literature covers a wide range of geometries, from particle tracking at laboratory-scale (using X-ray or radioactive techniques, see [41][42][43]) to a few studies at large-scale [24,45].…”

Segregation of wood particles in a bubbling fluidized bed

“…This radioactive particle tracking method for visualizing the fluidized bed interior is an efficient technique, although it involves complex materials. Recently, Fotovat et al [26] used the same experimental setup to analyze wood distribution in a sand fluidized bed; measurements were taken with a single tracer particle. They found a wood distribution all along the bed ( Fig.…”

Characterization of the upward motion of an object immersed in a bubbling fluidized bed of fine particles

“…More recently, Upadhyay and Roy [11] employed this method to explore the mixing and hydrodynamic behavior in a bed consisting of equal weight percentages of the same size particles differing in density. On the basis of the RPT data, Fotovat et al [6] realized that the average rise velocity of biomass particles is about 20% of the average bubble rise velocity, consistent with the findings of Soria-Verdugo et al [1].…”

“…Moreover, they observed that the object rising velocity hardly varies with its density or size. Employing the radioactive particle tracking (RPT) technique, Fotovat et al [6][7][8] provided insight into the circulation behavior and velocity profile of large cylindrical biomass particles fluidized with sand under bubbling conditions. RPT is a powerful non-invasive method that provides the instantaneous 3-D position of the tracked particle in a Lagrangian framework.…”