Conception d’un nouveau type de colonne pulsée appliquée au contact solide/liquide

Cette étude porte sur la conception d’une nouvelle technologie de colonne pulsée appliquée au contact solide/liquide. L’originalité du concept développé réside dans l’introduction d’internes et d’un mode de pulsation qui permettent de contrôler le temps de séjour solide indépendamment de celui du liquide. La faisabilité du concept et la caractérisation du comportement hydrodynamique des deux phases ont été étudiées sur un pilote semi-industriel, en réalisant des DTS sur des systèmes modèles. Un cas réel a ensuite été mis en oeuvre dans la colonne, afin d’illustrer les avantages du nouveau procédé en termes d’efficacité du transfert de matière. Il apparaît, au final, que le dispositif permet de réduire sensiblement la dispersion granulométrique et de prolonger le temps de séjour du solide, tout en réduisant la consommation en solvant. Les qualités de la nouvelle colonne conçue en font un appareil particulièrement adapté aux systèmes solide/liquide nécessitant un temps de contact prolongé. Grâce à une technologie innovante et à un réglage fin des paramètres opératoires, il est ainsi rendu possible d’intensifier le contact solide/liquide. ABSTRACT : This work deals with a novel type of pulsed column used as a solid/liquid contactor. An evolution in the design of the internals and in the shape of the pulsation has been set up. The initial objectives were to achieve a contactor of much longer solid residence time, independently of the liquid phase behaviour. Phase contacting is carried out countercurrently, solid is fed in at the bottom of the column and flows upwardly, regardless of the density difference between both phases. First, the technical feasibility was demonstrated. Then, the behaviour of solid and liquid phases was investigated through the analysis of residence times distributions. And, mass transfer efficiency has been evaluated with an industrial case. It was found that the column could enhance solid residence times, reduce granulometric segregation and solvent consumption. The new contactor seems to be particularly suitable for cases where a long contact between both phases is needed. Thanks to innovative internals and to an optimal tuning of the operating conditions, intensification of solid/liquid contacting was finally achieved

Use of the pulsation to control a polydispersed particles flow in a new type of pulsed column

New internals have been designed and implemented in a semi-industrial continuous solid-liquid pulsed column. By coupling these internals with a non sinusoidal pulsation, a better control of polydispersed solid particles is achieved. The pulsation is composed of a mixing step during which only the liquid flows through the column and an impulsion step designed to transport the solid phase from stage to stage. Solid and liquid phase behaviours are characterized thanks to residence time distribution measurements. This study demonstrates the strong impact of the pulsation and of the liquid flow rate during the impulsion to reduce the particles segregation inside the pilot. The effects of operating parameters on the liquid phase are also investigated and the choice of an operating compromise is discussed to balance advantages and drawbacks on the process

Conception d'un nouveau type de colonne pulsée appliquée au contact solide-liquide

Cette étude porte sur la conception d'une nouvelle technologie de colonne pulsée appliquée au contact solide/liquide. L'originalité du concept développé réside dans l'introduction d'internes et d'un mode de pulsation qui permettent de contrôler le temps de séjour solide indépendamment de celui du liquide. La faisabilité du concept et la caractérisation du comportement hydrodynamique des deux phases ont été étudiées sur un pilote semi-industriel, en réalisant des DTS sur des systèmes modèles. Un cas réel a ensuite été mis en oeuvre dans la colonne, afin d'illustrer les avantages du nouveau procédé en termes d'efficacité du transfert de matière. Il apparaît, au final, que le dispositif permet de réduire sensiblement la dispersion granulométrique et de prolonger le temps de séjour du solide, tout en réduisant la consommation en solvant. Les qualités de la nouvelle colonne conçue en font un appareil particulièrement adapté aux systèmes solide/liquide nécessitant un temps de contact prolongé. Grâce à une technologie innovante et à un réglage fin des paramètres opératoires, il est ainsi rendu possible d'intensifier le contact solide/liquide.This work deals with a novel type of pulsed column used as a solid/liquid contactor. An evolution in the design of the internals and in the shape of the pulsation has been set up. The initial objectives were to achieve a contactor of much longer solid residence time, independently of the liquid phase behaviour. Phase contacting is carried out countercurrently, solid is fed in at the bottom of the column and flows upwardly, regardless of the density difference between both phases. First, the technical feasibility was demonstrated. Then, the behaviour of solid and liquid phases was investigated through the analysis of residence times distributions. And, mass transfer efficiency has been evaluated with an industrial case. It was found that the column could enhance solid residence times, reduce granulometric segregation and solvent consumption. The new contactor seems to be particularly suitable for cases where a long contact between both phases is needed. Thanks to innovative internals and to an optimal tuning of the operating conditions, intensification of solid/liquid contacting was finally achieved.TOULOUSE-ENSIACET (315552325) / SudocSudocFranceF

An innovative pulsed column applied to solid-liquid contacting: the BPC column

The innovative process presented is a novel type of pulsed column (BPC column) used as a solid/liquid contactor. An evolution in the design of the internals and in the shape of the pulsation has been set up. The initial objectives were to achieve a reactor of greatly longer solid residence time, independently of the liquid phase. Phase contacting is carried out in a 1.5 m height column. Liquid and solid are flowing countercurrently. Solid is fed in at the bottom of the column and flows upwardly, whatever the density difference between both phases. The behaviour of solid and liquid phases was investigated through the analysis of residence time distributions. The working conditions range has been determined and it was found that an optimal tuning of the operating conditions (pulsation parameters, flows control…) could minimize the influence of the size and the density of particles and uncouple residence times of both phases. The column has been manufactured, in order to handle a large range of solid-liquid systems (solid treatment, purification or reaction, raw materials, floating or dense particles, polydispersed particles). On the basis of the model calculations and design considerations, preliminary data can be given on the technical and economical feasibility of the various applications quoted above. The final aim of this study is to prove that, for a fixed production rate and a product quality, the new column can satisfy the specifications required and even exceed them

A new pulsation policy in disc and doughnut pulsed column applied to the solid-liquid extraction of andrographolide from plants

Classically, sinusoidal oscillations are imposed to enhance mixing and mass transfer between two phases contacted. But, in any case of solid/liquid contact, it was noticed that this pulsation mode was not efficient enough to allow a controlled behaviour of the solid phase. The problem is particularly met for the treatment of raw plants or polydispersed populations with complex physical properties. The objective of this study is to demonstrate the viability of using a non-sinusoidal pulsation in a continuous contactor to replace a traditional batch sinusoidal mode. A review of the different pulsation techniques is firstly presented. The example of solid-liquid extraction of Andrographolide from plants has then been choosen to bring out the advantages of the new pulsation mode. The development of this application as a continuous process in a column has indeed encountered difficulties due to the important heterogeneity of the matter : one of these classes tends to float and the other to sink, which always leads to a definitive flooding in classical operations. Typically, the proposed signal is composed of two different periods : in one hand, a classical sinusoidal pulsation step used to mix the liquid and solid phases in the active part of the column and allow an optimal mass transfer and, in a second hand, an impulsion phase, used generally for the transport of solid. The extraction is carried out in a disc and doughnut column of 54 mm in diameter, and 3.5 m in height. Liquid and solid are flowing cocurrently and downwardly. Experiments have been performed to know the global characteristics of the process in steady state and to suggest some elements for industrial design. The results showed that an optimal tuning of the geometric characteristics of the column, the level of interface and the parameters of the pulsation, could increase the operated domain where flooding is avoided

Properties of Membranes Containing Semi-dispersed Carbon Nanotubes.

Carbon nanotubes exhibit superior mechanical and electrical properties that make them attractive for developing new composite materials. In this research, we examined the properties of ultrafiltration membranes made from carbon nanotube/polymer composites. Multiwalled carbon nanotubes (MWCNT, 4% w/w) were incorporated into polysulfone ultrafiltration membranes, prepared according to the wet phase inversion method. The dispersion of the nanotubes and the morphology of the membranes were observed by scanning electron microscopy. The membranes were characterized for surface roughness, contact angle, permeability, and mechanical properties. A partial deaggregation of the nanotubes leads to individual nanotubes within the polymer aswell as bundles nested in the pores. After addition of MWCNTs, the assymetric structure of the membrane, the permeability, and the hydrophobicity were not disturbed, but the roughness increased. Contrary to expectations,the tensile strength of the composite membrane was not improved while the elongation to failure decreased because of a lack of dispersion of the nanotubes. Growth of bacteria on the membranes was tested using two different methods, neither of which indicated an antibacterial effect due to the presence of nanotubes