(684e) Advanced Gamma-Ray Densitometry (GRD) Technique to Measure Gas and Liquid Holdups in Bench Scale Hydrotreater Reactors

Advanced Gamma-ray
Densitometry (GRD) Technique to Measure Gas and Liquid Holdups in Bench Scale Hydrotreater
Reactors.

Mohammed Al-Ani^a,
Hamza AlBazzaz^b, Muthanna H. Al-Dahhan^ac

a  Chemical and
Biochemical Engineering Department, Missouri University of Science and
Technology, Rolla MO 65409, USA

b Kuwait
Institute for Science Research, P.O. Box 2488,13109 Kuwait

 c Mining and Nuclear
Engineering Department, Missouri University of Science and Technology, Rolla,
MO 65409, USA

Email: aldahhanm@mat.edu

Trickle bed reactors are one of important hydrotreater
reactors. Trickle bed reactors (TBRs) are multiphase catalytic reactors in
which gas and liquid flow in concurrent downflow through solid particles (bed).
TBRs have been used widely in the refineries field particularly in the
hydrotreating processes (hydrodesulfurization, hydrogenation…etc.).  The hydrotreating processes represent one of
the essential processes in the industry due to contribute to reducing
contaminant gases emission to the atmosphere. Bench-scale reactors broadly
implemented to investigate the kinetics reaction and hydrodynamics as a part of
scale-up approach or develop and improve industrial-scale system that called
scale down approach. However, high importance for scale up and scale down
approaches on the reactor performance, using advanced measurement techniques
still in need to assess and measure different critical parameters with high
accuracy in the bench-scale reactors.

Phase holdup in the packed bed reactors represents
phase volume fraction in the bed. Gas and liquid holdup profiles are considered
as a critical parameter due to significantly impact different design
parameters. Gas and liquid holdup depend on gas flow rate, liquid flow rate,
bed characteristics (shape and size of packed bed), and physical properties for
fluids flow in the bed.

High accuracy and reliability to measure gas and
liquid holdups are necessary for the bench-scale reactors. Gamma-ray
densitometry (GRD) is one of effective industrial technique due to several
attributes high reliability, non-invasive measuring which no need to interrupt
the operating in the system, simplicity and flexibility in collect data along
bed height within a diametrical profile. GRD technique constructed and
developed in Multiphase Flow Reactor Engineering and Application Laboratory
(MFReal) at Missouri University of Science and Technology. The general concepts
for GRD are based on the photon count measurement. The basic principle of GRD
technique is the differences in the density of materials in the column which
the number of photon counts that reach the detector will be changed. The source
Cs-137 with initial activity of approximately 250 mCi. The source housed inside
a sealed chamber of lead from all direction except one that was represented as
a collimator for a beam of radiation. Developed methodology applied to determine
phase holdup in the multiphase flow reactor.

Many researchers have been investigated the
hydrodynamics in TBRs using invasive techniques or even global measurements
techniques. The results have been indicated high reliability for GRD to measure
phase holdup profiles in the packed beds. Moreover, the effects of gas flow
rate and liquid flow rate, and bed characteristics (shape and size of catalyst
particles) on the phase holdup profiles at different bed height level axially
in the hydrotreater catalytic reactor.