Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Fluidized Bed

Experimental Study of the Influence of Baffles on Hydrodynamics of Gas- Solids Fluidized Bed System

Jamal M. Ali

Engineering and Technology Journal, 2013, Volume 31, Issue 5, Pages 861-878

The objective of the present study was to determine the effects of the internals baffles on the gas-solids fluidized bed hydrodynamics, using a circular fluidized bed of Geldert group B sand particles.
Bed expansion data were obtained for un baffled and two different types of baffled (rectangular and circular blades) gas-solids fluidized beds at varying operating conditions, namely air velocity ,particle size (755,424 , 205µm) and initial static bed heights.
Experimental work was carried out in (0.1m) diameter and (1m) height circular fluidized bed column.
The results of the study showed that the particle size affects the measured hydrodynamic behavior especially in the large particle size.
The insertion of baffles into a fluidized bed system improves the contacting efficiency of gas and particle phases.
The effect of rectangular baffles is more significant than the effect of circular baffles on the pressure drop in fluidizing bed.

A Study of Chaotic Behavior of Heat Transfer In Gas-Solid Fluidized Bed

e Al-Rubeai; Jamal Mane; Nabeel Majid Aliwi

Engineering and Technology Journal, 2010, Volume 28, Issue 10, Pages 2027-2042

Fluidized beds are characterized by high heat transfer rates between the
bed and internal surfaces and have uniform temperature distribution that can be
achieved in fluidized bed systems. In the same time there is a chaotic behavior of
hydrodynamic and heat transfer in gas-solid fluidized bed.
Experimental work was carried out in gas-solid (air – sand) fluidized bed to
investigate the steady state heat transfer coefficient. The bed column used was
(172) mm in diameter and (1000) mm height, fitted with immersed cylindrical
heating element of (25.4) mm in diameter. The fluidizing medium was air flowing
at different velocities from fixed bed to fluidized bed of (0.006-0.078)m/s, and
three different sizes of fine sand particles were used (i.e. 63, 112, and 145 μm),
these average particles diameters were estimated by two methods (Wide and
Narrow Range Solids).
A comparison have been done with values of the minimum fluidizing velocity that
calculated analytically, empirical, and which got experimentally. The results show
a chaotic behavior of hydrodynamic gas-solid fluidized bed.
The heat transfer coefficient and the bed viodage increase with increasing gas
fluidizing velocity and the heat transfer coefficient decreases with an increase in
particle diameter.
Two empirical correlations are proposed which can calculate wide range solids and
narrow range solids based on experimental data. The Nusselt number presented
with some dimensionless groups as follows:-
For Wide Range Solids Nu = 0.81Re0.94 Pr0.35
Where the correlation coefficient (R) was equal to (0.92) and the average absolute
relative error was (12.62 %).
For Narrow Range Solids Nu = 0.45Re0.65 Pr0.33
Where the correlation coefficient (R) was equal to (0.86) and the average absolute
relative error was (24.2 %).