Mechanism Of Granule Growth Research Articles

Mathematical Model in the Kinetics of Agitation Fluidized Bed Granulation. Effects of Moisture Content, Damping Speed and Operation Time on Granule Growth Rate.

A population balance equation, in which moisture content was taken into consideration for the coalescence probability of two colliding granules, was proposed to investigate the kinetics of granule growth in agitation fluidized bed granulation. The effects of operating variables such as moisture content, damping speed and operation time on the granule growth and its rate were numerically examined. It was found that the theoretical results intrinsically revealed these effects on granule size, size distribution and granule growth rate. The theory also showed good agreement with the experimental granulation data for pharmaceutical powders. As a result, the granule growth mechanism in agitation fluidized bed granulation was elucidated in detail.

Scale-Up of Agitation Fluidized Bed Granulation. IV. Scale-Up Theory Based on the Kinetic Energy Similarity.

The scale-up theory based on kinetic energy similarity was proposed to elucidate the scale-up characteristics in agitation fluidized bed granulation. In this model, kinetic energy given to granules by agitator rotation and fluidizing air were taken into consideration. It was found that granule mass median diameter, apparent density and shape factor can be well expressed by the parameter (Rω/u)2, which showed the ratio of kinetic energy by agitator rotation to that by fluidizing air. Based on the results obtained, effects of operational variables and scale factor on the granule properties could be explained theoretically and granule growth mechanism in agitation fluidized bed granulation was elucidated in detail.

Moisture feedback control and process automation in fluidized bed granulation

A new practical method for self-control of the fluidized bed granulation process will be described. The method consists of moisture feedback control and program control of each operation (i.e. mixing, granulation and drying). An IR moisture sensor which is resistant to powders and dusts has been designed and developed to continuously measure and control the granule moisture content in fluidized bed granulation. The effect of the moisture content, imbibition rate and time required for fixed command control on granule growth is discussed, and a model of agglomeration and the mechanism of granule growth is proposed. On the basis of the results obtained granule growth was fully controlled by means of the moisture feedback control and, in addition, automation of the fluidized bed granulation process was eventually established.

The crushing and layering mechanism of granule growth

Equations for the kinetics of granulation by the crushing and layering elementary mechanism of granule growth have been derived. Expressions for granule-size spectra as a function of granulation time are presented. It is shown that the size distribution eventually becomes “self-preserving” in terms of an appropriate dimensionless granule size. The theoretical results are in reasonable agreement with the published experimental data.

Granulation of Griseofulvin

Griseofulvin, in fine and coarse grades, has been bowl granulated using binder solutions. The granules have been assessed for strength and flow characteristics. A mechanism of granule growth has been suggested, which satisfactorily explains the experimental results.