Author    :   Satoru Watano, Ph.D.
                         Department of Chemical Engineering, Osaka Prefecture University
                         Sakai, Osaka 599-8531, Japan

Abstract :

Granulation, defined as a process of size enlargement, is widely used in order to produce particle materials having desired size, density, shape and other physical properties. Among different techniques applied, the use of a high shear granulation has increased considerably in recent years because this type of wet granulation has significant advantages in producing spherical and well-compacted granules in a very short time (5 to 20 min). It is reported, however, that the high shear granulation is very sensitive to the initial powder properties, binder content and etc. Therefore there is a great need for reliable instrumental methods for process monitoring and determination of operational end point. Although torque of driving shaft or power consumption of motor drive has already been measured, no reliable system for continuously detecting and controlling granule growth has been developed yet. In this study, continuous measurement and self-control of high shear granulation has been conducted. A particle image probe comprising a CCD camera, a high-speed lightning device and an air purge device has been developed for detecting granule image continuously. A high-speed image processing system is also developed to analyze the granule image continuously. By means of the systems, granule size distribution and shape can be computed in real time to analyze the granulation process. Fuzzy logic using a linguistic algorithm employing if-then rules is adopted to control granule size under various powder samples and operating conditions. It is found that the system is able to control granule growth in a high shear granulation with high accuracy, regardless of changes in powder samples and operating conditions.