(547b) Impact of Configuration of Heat Exchanging Internals on Symmetric Behavior of Bubble Dynamics of a Bubble Column

Impact of configuration of Heat
Exchanging Internals on Symmetric Behavior of Bubble Dynamics of a Bubble
Column

Ahmed
Jasim1, and Muthanna Al-Dahhan*

1,*Chemical
Engineering and Biochemical Engineering Department

Missouri
University of Science and Technology, Rolla, MO 65409-1230. USA

Email:aaj3k5@mst.edu

Abstract

        Bubble column
reactors have many industrial applications including processes with exothermic
reactions, such as F-T synthesis for converting syn gas to liquid fuels. Heat
Removal internals are used to keep these processes at a desired temperature. Earlier
studies reported that internals alter the hydrodynamics, mixing pattern, bubble
dynamics, heat and mass transfer and hence the bubble column performance. There
is no unified geometrical standard of internals design in the open literature
to optimize these parameters in bubble column reactor equipped with internals. Uniform
distribution of the internals over the cross- sectional area impact the flow
field in the reactor. Accordingly, in this work three different configurations were
studied. First configuration is a hexagonal arrangement of 30 tubes with 0.5
inch outside diameter of each tube. Second configuration is a very uniform circular
arrangement of 30 tubes of  0.5 inch outside
diameter, in which two types of tube end bottom shape were investigated, which
are tapered and U-Tube. The third configuration is also a uniform circular
arrangement but of 8 tubes of 1 inch outside diameter of each.  These configurations have same cross-section
area covering 25% of the column's cross-section area to simulate those used if
F-T process. Hexagonal arrangement by virtue of its geometric configuration
creates distinguished free areas between the edges and column wall which would cause
extreme channeling for the majority of gas to flow through. Hence uniform
circular arrangement was studied to see the effect of free surface formation in
hexagonal arrangement.This study aimed to investigate the impact of these heat
exchanging tubes on bubble dynamics and  the symmetric behavior of bubble dynamics in
bubble column by studying local radial profiles of each of gas hold up,
gas-liquid interfacial area, bubble density, bubble chord length, and bubble
rise velocity at r/R= -0.9, -0.6,-0.3, 0, 0.3, 0.6, 0.9 in the fully developed
region by using 4-point optical fiber probe. The experimental work was carried
out in a 14 cm inner diameter Plexiglas bubble column using air-water semi
batch system. The gas introduced into the column at velocities (5, 15, 30, and 45)
cm/s based on free cross-section area of the column. The results and finding
will be presented and discussed in this presentation

Keywords: Bubble column, internals gas hold
up, gas-liquid interfacial area, bubble density, bubble chord length, bubble
rise velocity.