Mechanism for particle movement in gas-fluidized beds was studied both from the theoretical and experimental points of view. In a two-dimensional fluidized bed particle trajectories were photographed when a bubble passed through

Carlson, R. E.

Gabor, J. D.

English

NASA Technical Reports Server

December 1968
	
Brief 68-10407 
. RGY  
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TES
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the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
An Investigation of Particle Mixing in a Gas-Fluidized Bed 
An experimental investigation of the movement of 
particles in a fluidized bed has been conducted by 
R. E. .Carlson of Argonne National Laboratory, 
Argdnne, Illinois. A paper, "An Investigation of the 
Mecha ni s m of Particle Mixing in a Gas-Fluidized 
Bed," is available which comprehensively discusses the 
theories behind the work, previous studies, experi-
mental techniques, and results of the investigation. 
The work was conducted in support of a theory by 
John D. Gabor, also of Argonne. Previously used 
experimental techniques were extended to determine 
the effect of particle size and column diameter. 
A major problem with the use of fluidized beds is 
the lack of understanding of how particles circulate in 
the bed. A clearer picture of the mechanism for par-
ticle movement should aid in the development of more 
universal correlations for heat and mass transfer. 
Thus, in the present investigation, the mechanism 
for particle movement in gas-fluidized beds is studied 
both from the theoretical and experimental points of 
view. 
Gabor's theory, which is based on the stream func-
tion for an ideal fluid describes particle trajectories 
and drift profiles for the case of a bubble rising mid-
way between parallel walls. 
In order to test Gabor's theory, a "two-dimen-
sional" fluidized bed was used to observe how par-
ticles in the interior of a fluidized bed move when a 
bubble passes through. This bed consisted of a 
parallelepiped whose thickness was small compared to 
its length and width. This method approximated a 
thin vertical slice from the center of a cylindrical bed. 
Two columns were used. The front and back plates 
were made of pyrex glass, coated on the sides facing
the beds with a mixture of antimony and tin oxides. 
This coating conducts away static charges which build 
up at the walls from friction of the glass heads used as 
bed material. Besides the glass beads, black particles 
of the same size were used in each experiment as 
tracers. Actual height of fluidized material in the bed 
was 10" 
The bed was fluidized by nitrogen from a sintered 
brass porous distributor plate. While air flow was kept 
at that for incipient fluidization (such that few or no 
bubbles formed), an additional burst of nitrogen was 
introduced through an orifice in the distributor plate. 
Bubbles intrOduced in this way could be controlled at 
the desired size and frequency by a solenoid valve and 
a two-cycle timer. 
By photographing the bed as a bubble passed 
through, the particle trajectories could be determined. 
High speed motion pictures were taken with a Fastax 
camera operating at 400 f.p.s. with Ektachrome film. 
The film was then analyzed frame by frame with a 
Vanguard Motion Analyzer. 
The net displacements caused by the trajectories 
were plotted versus distance from the wall to obtain 
drift profiles. 
Notes: 
I. This information is an advance in the understand-
ing of fluidized beds which may permit scale-up of 
models. 
2. Since fluidized beds are used in the catalytic crack-
ing of petroleum, the calcination of limestone, the 
roasting of ores, cement manufacture, drying of 
solids, vapor disposition, etc., the information may 
be of interest to researchers in these fields. 
(continued overleui( 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son acting on behalf of the United States Government assumes any
liability resulting from the use of the information contained in this 
document, or warrants that the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19680000407 2020-03-12T05:56:15+00:00Z
Inquiries concerning this innovation may be di-
rected to:
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B68-10407 
Source: R. E. Carlson and J. D. Gabor 
of the Chemical Engineering Division 
(ARG-10182)
Patent status: 
Inquiries about obtaining rights for commercial 
use of this innovation may be made to: 
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commssion 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439 
Brief 68-10407	 Category 05


An investigation of particle mixing in a gas-fluidized bed

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