TITLE:
Radiotracer Investigation of the Effect of Impeller Type on Mixing in Industrial Process Simulator
AUTHORS:
Simon Yao Adzaklo, Christian Priesley Kofi Dagadu, Ishmael Iddisah Mumuni, Patience Adwoa Serwah Adu, Hannah Asamoah Affum, Godfred Kofi Appiah, Alexander Coleman
KEYWORDS:
Axial, Impellers, Mixing, Radial, Radiotracer
JOURNAL NAME:
Journal of Applied Mathematics and Physics,
Vol.6 No.3,
March
14,
2018
ABSTRACT: Radiotracer technology has been applied in industry for
the investigation of process performance, online monitoring of conditions of
process units, troubleshooting and diagnosing anomalies including mixing
conditions in continuous stirred tank reactors. In this study, radiotracer
methodology was used to carry out investigation on a laboratory water flow rig
which serves as simulator of industrial processes. The aims of the
investigation were to assess: i) the effect of impeller type on mixing and ii)
the fluid dynamics of the water in the vessels since both the vessels and the
impellers were redesigned and reconstructed. Four similar vessels in series
circuit with different impeller configurations were investigated. Tank 1 has 1
axial impeller, Tank 2 has 2 axial impellers, Tank 3 has 2 radial impellers and
Tank 4 has no impeller. The data were collected by
introducing 8 mCi liquid technetium-99 m at the inlet stream
of the vessels and the gamma signal was detected with thallium activated NaI
detector placed at the outlet of the vessels. Residence Time Distribution (RTD)
curves for the outlet tracer concentration were generated from which the Mean
Residence Time (MRT) and the variance were calculated by the method of moments.
The extent of material mixing in the vessels was inferred from the variances
and the fluid dynamics was obtained by modeling. The extent of mixing was
highest in Tank 2 followed by Tank 3, and Tank 4 gave the poorest mixing. The
outlet response curves were fitted with mathematical models using DTS pro and
“RTD Software”. The best fit for Tanks 2, 3 and 4 was Perfect Mixers in Series
with Exchange (PMSE) model while Perfect Mixers in Series with Recycle (PMSR)
model best described the fluid dynamics of the material in Tank 1.