Measuring and modelling lateral solid mixing in a three-dimensional batch gas-solid fluidized bed reactor

A 0.27 m diameter fluidized bed reactor has been designed to allow experimental measurement of the axial and radial mixing behaviour of the solids. A unique method has been developed which permits the continuous determination of solid tracer concentration with time at different radial and axial positions within the fluidized bed. Solids mixing has been described by a model in which vertical mixing is instantaneous and lateral mixing occurs by dispersion. The lateral solids dispersion coefficients have been evaluated at various operating conditions from the experimental results of tracer concentration versus time. Based on the results, a modification of an existing correlation is proposed. On a concu un reacteur a lit fluidise de 0.27 m de diametre, qui permet de mesurer experimentalement le comportement des melanges axiaux et radiaux des solides. On a mis au point une methode unique qui permet la determination continue de la concentration d'un traceur solide en fonction du temps, a differentes positions radiales et axiales a l'interieur du lit fluidise. On decrit le melange des solides au moyen d'un modele, dans lequel le melange vertical est instantane et le melange lateral se fait par dispersion. Les coefficients de dispersion laterale des solides ont ete evalues dans differentes conditions operatoires, a partir des resultats experimentaux de la concentration du traceur en fonction du temps. On propose, a partir des resultats obtenus, une modification d'une correlation existante.