Diffusing wave spectroscopy (DWS), a non-intrusive multiple scattering technique, can be used to study the fundamentals of particle motion in dynamic dense granular media and measure the mean of the square of the particle velocity fluctuations about their mean, which is related directly to the so-called 'granular temperature' that underpins many theories for dynamic granular processes. An overv...

A laboratory, fluidized-bed gasifier is being researched as a means to gasify feedstocks in a process to produce ethanol from biomass. Fluidization characteristics of the bed, especially minimum (Umf) and complete (Ucf) fluidization velocities, were measured because they are critical to the operation of the gasifier. Fluidization properties of sand and chopped switchgrasssand mixtures of differ...

The fluidized bed drying principles for drying of tea in Bangladesh is thoroughly studied. The experiments were conducted to determine the drying curve, drying time, drying constant and dynamic equilibrium moisture contents of tea at the Bangladesh Tea Research Institute. Drying of tea in a fluidized bed dryer (Kilburn Vibro Fluid Bed Dryer) takes only 20 min for drying from an initial moisture...

Palm kernel shell is an important bioenergy resource in Thailand. However, due to elevated alkali content in biomass ash, this oil palm residue shows high tendency to bed agglomeration in a fluidized-bed combustion system using conventional bed material (silica sand). In this study, palm kernel shell was burned in the conical fluidized-bed combustor (FBC) using alumina and dolomite as alternati...

A bench-scale updraft gasifier was used as a fluidized- and fixed-bed gasification unit in three modes (fluidized-bed at equivalence ratios (ER) =0.2 and 0.25, and a mode in fixed-bed). The experiments were done in five different temperatures (650, 700, 750, 800 and 850oC). To obtain the required data to develop a thermodynamic equilibrium model, the proximate and ultimate analysis w...

We demonstrate that a fluidized bed of hard spheres during defluidization displays properties associated with formation of a glass. The final state is rate dependent, and as this state is approached, the bed exhibits heterogeneity with increasing time and length scales. The formation of a glass results in the arrest of macroscopic particle motion and thus the loss of fluidization. Microscopic m...

We demonstrate that a fluidized bed of hard spheres undergoes a glass transition during defluidization. As in other glass-forming systems, the dynamics of the bed becomes heterogeneous as the transition is approached; spatial and temporal correlation scales increase rapidly. Microscopic motion persists in the glass state, but the bed can be jammed (all motion arrested) by application of a small...

In this study hydrodynamics of a fluidized bed reactor with fumed silica nano particles was modeled using CFD method. Hydrodynamics parameters such as gas and solid velocity and void fraction have been investigated. The minimum fluidization velocity was around 0.0115 m/s at solids volume fraction of 0.0077. Fluidization process was involving a high expansion ratio of bed and without large bubbl...

Fluidized beds have been widely used in power generation and in the chemical, biochemical, and petroleum industries. The 3D simulation of commercial scale fluidized beds has been computationally impractical due to the required memory and processor speeds. However, in this study, 3D Computational Fluid Dynamics simulation of a gas-solid bubbling fluidized bed is performed to investigate the effe...

Porous carriers in fluidized bed have been used for microbial immobilization in order to simultaneously remove organic carbon and nitrogen in wastewater. In particular, multifunctional microbial reactions in the carrier, such as simultaneous nitrification/denitrification, play important roles in nitrogen removal. To enhance these reactions the substrates should be supplied into the carrier with...