Fluidized-Bed and Related Granulators

In the fluid-bed granulation process, moisture control is the key parameter that needs to be controlled. Faure et al. (133) have used process control for scale-up of a fluidized bed process. They used infra-red probes to monitor moisture. As there are normally large numbers of inter-related variables, they used computerized techniques for process control, such as fuzzy logic, neural networks, and models based on experimental techniques. 

This chapter focuses on the use of fluidized bed granulation process in the development and preparation of low-dose granule formulations for further conversion to immediate release tablets for personal administration. As a reference document, the chapter does not cover some very common subjects such as process safety, material characterization techniques and basic process and instrumentation technologies. Because the authors intention is to relate their experience in this specialized area, these areas are not discussed in any depth however their omission does not reduce their importance. 

Hemati, M., Cherif, R., Saleh, K., and Pont, V., Fluidized bed coating and granulation Influence of process-related variables and physicochemical properties on the growth kinetics. Powder TechnoL, 2003,130,18-34. 

The approach taken here is to employ standard materials characterization tests to measure the materials properties of the granulated product. With this information, the mechanism of attrition, i.e., breakage versus erosion, is determined. The rate of attrition can then be related, semi-empirically, to material properties of the formulation and the operating variables of the process, such as bed depth and fluidizing velocity. 

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