The axial dispersion in the liquid phase of a trickle-bed column is mainly affected by velocity d... more The axial dispersion in the liquid phase of a trickle-bed column is mainly affected by velocity distributions appearing at the particle and bed scales. At the particle scale, this phenomenon is represented by a laminar pore flow model (regime of low gas-liquid interactions). At the bed scale, the axial dispersion is analyzed using a lattice approach based on the percolation theory. We propose a theoretical expression for the axial dispersion coefficient evidencing the influence of the fluid flow hydrodynamics and, more specifically, of the particle irrigation rate. A decrease of this parameter leads to an increase of the dispersion coefficient. The model is compared with various experimental data. Good agreement is obtained for the influence of the liquid viscosity and the particle wettability.
Trickling filters are used for a long time in the biological treatment of municipal and industria... more Trickling filters are used for a long time in the biological treatment of municipal and industrial waste waters. During recent years, they have gained a new popularity by reason of their simplicity of use as well as their low energy requirement and operating costs. Despite this industrial importance, the mechanisms of this type of reactor are not yet fully understood. Most of the models proposed in the literature are totally or partially empirical and rather far from the actual complexity of the phenomena. These models may be grouped into three classes :
We present a simple description of a gas-liquid flow through a packed bed under trickle flow cond... more We present a simple description of a gas-liquid flow through a packed bed under trickle flow conditions. A careful examination of the physics of the phenomena leads us to model the flow as a directed percolation process on a random network. Two accessibilities are introduced: the static accessibility resulting from the random distribution of the geometric properties of the packing and the dynamic accessibility resulting from energetical requirements. Under usual flow conditions (very far from the critical region) and for usual packing (no correlation between the two accessibilities) a simple model leads to the flow rate distribution. It is compared with experimental results obtained on a pilot scale trickling filter.
Realisation d’une etude hydrodynamique lagrangienne decrivant grâce a des outils experimentaux (P... more Realisation d’une etude hydrodynamique lagrangienne decrivant grâce a des outils experimentaux (PEPT, CARPT, trajectographie optique...) ou des simulations assistees par ordinateurs (CFD) les trajectoires suivies par une cellule ou un microporteurs sur un temps suffisamment long et des lors la frequence de rencontre des differents niveaux de stress. 50 19 11 9 80 37 14 14 120 rpm 77 34 21 13 85 63 21 22 85 rpm 85 64 35 22 95 80 36 40 50 rpm 2 1 2 1 2 1 2 1 31.06 cP 3.15 cP 31.06 cP 3.15 cP d/D=0.5 d/D=0.4 Installation experimentale
The porous texture of oceanic polymetallic nodules used as catalysts for demetallatton and desulp... more The porous texture of oceanic polymetallic nodules used as catalysts for demetallatton and desulphurization of petroleum residua in a trickle bed reactor was studied after reaction. Four techniques were considered: analysis of nitrogen physical adsorption-desorption isotherms, X-ray diffractometry, mercury penetration and electronic microscopy. The nodules present a remarkable specific surface area and porosity, which ar0 partially cor~erved at high temperature s even under the drastic conditions of hydrotreatment.
A new phenomenologlcal description of the hydrodynamic and mass transfer processes occurrlng In a... more A new phenomenologlcal description of the hydrodynamic and mass transfer processes occurrlng In a trickle-bed reactor is presented. The proposed model, which account for the random and dlscontlnuous nature of the packed bed, 1s checked with hydrotreating data previously publlshed in the literature. These data may be single wetting parameter introduced on physlcal ground. KEYWORDS Chemical reactlon englneerlng, trickle-bed reactors, two-phase mass transfer, llquld-solid contacting efflclency, percolation S1S. hydrotreatment of petroleum fractions.
Carbon materials issued from evaporative drying and pyrolysis of resorcinol-formaldehy gels were ... more Carbon materials issued from evaporative drying and pyrolysis of resorcinol-formaldehy gels were used as metal catalyst supports. These carbons, whose pore texture and composition are controllable, lead to high metal dispersion. Moreover, pore texture control is a great advantage: diffusional limitations can be lowered, and even eliminated, by choosing an appropriate pore texture range.
The axial dispersion in the liquid phase of a trickle-bed column is mainly affected by velocity d... more The axial dispersion in the liquid phase of a trickle-bed column is mainly affected by velocity distributions appearing at the particle and bed scales. At the particle scale, this phenomenon is represented by a laminar pore flow model (regime of low gas-liquid interactions). At the bed scale, the axial dispersion is analyzed using a lattice approach based on the percolation theory. We propose a theoretical expression for the axial dispersion coefficient evidencing the influence of the fluid flow hydrodynamics and, more specifically, of the particle irrigation rate. A decrease of this parameter leads to an increase of the dispersion coefficient. The model is compared with various experimental data. Good agreement is obtained for the influence of the liquid viscosity and the particle wettability.
Trickling filters are used for a long time in the biological treatment of municipal and industria... more Trickling filters are used for a long time in the biological treatment of municipal and industrial waste waters. During recent years, they have gained a new popularity by reason of their simplicity of use as well as their low energy requirement and operating costs. Despite this industrial importance, the mechanisms of this type of reactor are not yet fully understood. Most of the models proposed in the literature are totally or partially empirical and rather far from the actual complexity of the phenomena. These models may be grouped into three classes :
We present a simple description of a gas-liquid flow through a packed bed under trickle flow cond... more We present a simple description of a gas-liquid flow through a packed bed under trickle flow conditions. A careful examination of the physics of the phenomena leads us to model the flow as a directed percolation process on a random network. Two accessibilities are introduced: the static accessibility resulting from the random distribution of the geometric properties of the packing and the dynamic accessibility resulting from energetical requirements. Under usual flow conditions (very far from the critical region) and for usual packing (no correlation between the two accessibilities) a simple model leads to the flow rate distribution. It is compared with experimental results obtained on a pilot scale trickling filter.
Realisation d’une etude hydrodynamique lagrangienne decrivant grâce a des outils experimentaux (P... more Realisation d’une etude hydrodynamique lagrangienne decrivant grâce a des outils experimentaux (PEPT, CARPT, trajectographie optique...) ou des simulations assistees par ordinateurs (CFD) les trajectoires suivies par une cellule ou un microporteurs sur un temps suffisamment long et des lors la frequence de rencontre des differents niveaux de stress. 50 19 11 9 80 37 14 14 120 rpm 77 34 21 13 85 63 21 22 85 rpm 85 64 35 22 95 80 36 40 50 rpm 2 1 2 1 2 1 2 1 31.06 cP 3.15 cP 31.06 cP 3.15 cP d/D=0.5 d/D=0.4 Installation experimentale
The porous texture of oceanic polymetallic nodules used as catalysts for demetallatton and desulp... more The porous texture of oceanic polymetallic nodules used as catalysts for demetallatton and desulphurization of petroleum residua in a trickle bed reactor was studied after reaction. Four techniques were considered: analysis of nitrogen physical adsorption-desorption isotherms, X-ray diffractometry, mercury penetration and electronic microscopy. The nodules present a remarkable specific surface area and porosity, which ar0 partially cor~erved at high temperature s even under the drastic conditions of hydrotreatment.
A new phenomenologlcal description of the hydrodynamic and mass transfer processes occurrlng In a... more A new phenomenologlcal description of the hydrodynamic and mass transfer processes occurrlng In a trickle-bed reactor is presented. The proposed model, which account for the random and dlscontlnuous nature of the packed bed, 1s checked with hydrotreating data previously publlshed in the literature. These data may be single wetting parameter introduced on physlcal ground. KEYWORDS Chemical reactlon englneerlng, trickle-bed reactors, two-phase mass transfer, llquld-solid contacting efflclency, percolation S1S. hydrotreatment of petroleum fractions.
Carbon materials issued from evaporative drying and pyrolysis of resorcinol-formaldehy gels were ... more Carbon materials issued from evaporative drying and pyrolysis of resorcinol-formaldehy gels were used as metal catalyst supports. These carbons, whose pore texture and composition are controllable, lead to high metal dispersion. Moreover, pore texture control is a great advantage: diffusional limitations can be lowered, and even eliminated, by choosing an appropriate pore texture range.
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Papers by M. Crine