First International Conference on MOLDAVIAN RISKS – FROM ...

<strong>First</strong> <strong>International</strong> <strong>Conference</strong> on MOLDAVIAN RISKS - FROM GLOBAL TO LOCAL SCALE
16-19 May 2012, Bacau, Romania
AVOIDING RISKS IN SOLID-GAS DEPOLLUTION BY
CONTROLLING PARAMETERS IN FLUIDIZED BED
Gabriela Muntianu 1 , Ileana Denisa Nistor 1 , Cosmin Jinescu 2 ,
Gholamreza Djelveh 3
1 “Vasile Alecsandri” University of Bacau, Department of Chemical and Food Engineering,
Romania
2 Politehnica University of Bucharest, Departament of Mechanical Engineering, Romania
3 ENSCCF, LGCB, BP 206, Clermont Universite´, France
Corresponding author: Ileana Denisa Nistor, denisanistor@yahoo.com; dnistor@ub.ro
Abstract: The paper aims to avoid possible and emerging risk in gas depollution processes.
To achieve this desiderate the main technological parameters used in gas-solid depollution
processes with process intensification by using fluidization bed are studied. The use of the
fluidization bed as intensification technique in gas depollution provides higher
performance but also inconveniences in the bed granular structure. At higher flow
velocities of the fluidization agent gas bubbles that are distributed uniformly in the column
appear and their diameter increases slightly with the gas velocity. Gas bubbles create a
strong turbulence in the bed, which induces a strong mixing of solid phase and determines
permanent fluctuations of the fluidized bed height. Along with the increasing gas flow,
pistons appear, leading to turbulent fluidization regime. Bed structure vitiations, pistons
and total or intermediate channels appear as particular aspect of non-homogeneous
fluidization. The structure of the fluidization bed that is the main characterization index of
this technique also represents the main obstacle that limits the applications in gas
remediation. Practical applications of fluidized bed and the difficulties created by the
uneven structure of the bed, directed the research efforts towards the realization of a
fluidized homogeneous structure, increasing the efficiency of this technique in the
remediation of gasses. Homogeneous fluidization is characterized by a single and uniform
distribution of solid particles in bed and a uniform expansion of it. The distance between
solid particle increases with the velocity of the flow agent and the homogeneous fluidized
bed can be assimilated as a boiling liquid. Hydrodynamic parameters controlled in the
fluidized bed were diameter and density of solid particles, velocity of the fluidization agent
and the ratio between the height of fixed bed and diameter of fluidization column. The
paper proposes combining the advantages possessed by the natural clays (calcium and
sodium clay) as solid particles through the fluidization technique in order to improve the
gas remediation process.
Keywords: process intensification, fluidization properties, solid particle, fixed bed, fluidized bed.
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