Influence of Thermal Conditions on Particle Properties in Fluidized Bed Layering Granulation

Abstract

Fluidized bed layering granulation is frequently used to formulate particles of high quality.From previous studies, it is well known that the dynamic behavior of the process, as well as the product properties depend on operating parameters. The process is characterized by heat and mass transfer between fluidized particles and the surrounding fluidization medium. To investigate the mutual influence between particle phase and fluidization medium, a dynamic model is introduced. The model comprises two parts: a population balance model to describe the evolution of the particle sizes and a system of ordinary differential equations to account for thermal conditions. For the first time, the dynamic model considers the bidirectional coupling of particles and fluidization medium in fluidized bed layering granulation. By means of simulations, it is shown that the derived model is capable of reproducing the experimental findings.

Estimation of the dominant size enlargement mechanism in spray fluidized bed processes

“…In the literature, several approaches exist to model particle growth due to layering in spray fluidized bed processes. Compartment models divide the process chamber into two or more coupled zones (i.e., a spray zone and a drying zone) to account for dispersion of the particle‐size distribution during the growth process, see Sherony, Wnukowski and Setterwall, Maronga and Wnukowski, and Rieck et al As shown by Neugebauer et al, layering growth can also be modeled using a single compartment approach, which is used in this study for simplification. The resulting growth model is a single one‐dimensional population balance equation describing the transient behavior of the particle‐size distribution n due to layering: …”

Control of Particle Size and Porosity in Continuous Fluidized‐Bed Layering Granulation Processes

“…ð ÞdL which influences the heat and mass transfer between the phases. For the details the reader is referred to [11].…”

“…Particle porosity crucially depends on the thermal operating conditions such as the temperature and the moisture content of the fluidization gas or the injection rate of the solid solution or suspension in FBLG [10]. A quantitative dynamic model to predict the influence of the thermal conditions on the particle properties including the particle size distribution and the porosity was proposed recently in Neugebauer et al [11]. As described in the experimental work of Schmidt et al [12], thermal conditions may also influence the process stability, which is not yet taken into account in the model presented in Neugebauer et al [11].…”

“…A quantitative dynamic model to predict the influence of the thermal conditions on the particle properties including the particle size distribution and the porosity was proposed recently in Neugebauer et al [11]. As described in the experimental work of Schmidt et al [12], thermal conditions may also influence the process stability, which is not yet taken into account in the model presented in Neugebauer et al [11]. There, it was conjectured that particle porosity affects the comminution process in the mill, which is known to be crucial for stability.…”

“…A quantitative dynamic model to predict the influence of the thermal conditions on the particle properties including the particle size distribution and the porosity was proposed recently in Neugebauer et al. . As described in the experimental work of Schmidt et al.…”