Hydrodynamic behaviour of a gas—solid counter-current packed column at trickle flow
Trickle flow of a more or less fluidized catalyst through a packed column is a promising new gas—solid counter-current operation. The hydrodynamic, behaviour of such a column, filled with dumped PALL rings, has been investigated, while some results have been obtained with RASCHIG rings and cylindrical screens as packing. The solid used was a microspherical catalyst carrier. Pressure drop, hold-up, loading and flooding were evaluated and compared with literature data for gas—liquid systems. The behaviour is analogous although the absolute magnitude is different. 
 
Pressure drop is low, up to 50% of the solid being carried by the packing. A correlation for the pressure drop, which is mainly caused by suspended particles, has been derived. At low gas velocities particle velocity is constant, whilst near flooding the slip velocity between gas and solid reaches a constant value. Using empirical values for particle velocity and slip velocity, hold-up, loading and flooding can be predicted. Scaling-up problems still need to be investigated. Results on mass transfer, axial dispersion of both phases and solid spread factors will be published later.
Hydrodynamic study of gas and solid flow through a screen‐packing
Many drawbacks of conventional gas fluidized beds can be avoided by filling the column with a fixed wire-screen Raschig ring packing of high voidage. Such systems have been studied in batch and countercurrent continuous mode. Excellent fluidization occurs with relatively coarse particles but not with smaller particles. In batch systems, the expansion is given by a Capes and McIlhinney type power law and the contribution of the packing to support the bed can be up 20 percent of the weight of solid. In countercurrent systems, for each gas velocity two operating points can occur: the dilute or the dense phase bed in the same way as for gas liquid flow. All increases in the flow of the solid or in the dilution of the bed lead the packing to support a greater part of the grains. 
 
 
 
On peut eviter bien des inconvenients usuels des lits fluidises au gaz en remplissant la colonne avec un garnissage fixe de forte porosite et comprenant un anneau de Rasching avec tamis metallique. On a etudie des systemes de ce genre sous forme discontinue et sous forme continue a contre-courant; il s'y produit une excellente fluidisation dans le cas des particules relativement grosses, mais non pas lorsqu'il s'agit des particules plus petites. Dans les systemes discontinus, on obtient l'expansion au moyen d'une loi d'energie du genre de celle de Capes et McIlhinney et la contribution du garnissage au support du lit peut atteindre 20% du poids de la matiere solide. Dans les systemes a contre-courant, il peut se produire, pour chaque vitesse du gaz, un lit a phase diluee ou dense, comme dans le cas d'un ecoulement de gaz et de liquide. Toutes les augmentations dans l'ecoulement de la matiere solide ou dans la dilution du lit permet au garnissage de supporter une plus grande partie des grains.
Exopolysaccharide biosynthesis and related enzyme activities of the medicinal fungus, Ganoderma lucidum, grown on lactose in a bioreactor
Exopolysaccharide (EPS) production and biosynthesis were studied in Ganoderma lucidum, a fungus used in traditional Chinese medicine, grown with lactose in a bioreactor. β-Galactosidase activity, which implies the existence of a lactose permease system, was induced by lactose. Lactose feeding also increased α-phosphoglucomutase activity and EPS accumulation but decreased phosphoglucose isomerase activity and lactate concentration in the culture broth. A maximum cell density of 22 g l−1 and EPS at 1.25 g l−1 were obtained in fed-batch bioreactor culture.