Recent trials have demonstrated that the Parsum inline particle size analyser from Malvern Instruments can be used successfully to monitor particle growth in a fluidised bed.
Fluidised bed granulation is widely used in the pharmaceutical sector, but process control is frequently problematic and based on operator experience or trial and error rather than effective monitoring. Inline analysis and automated control can deliver dramatic efficiency gains and improvements in product quality/consistency; the key is finding analysers that meet the requirements of the application.
Complex flow regimes, high humidity and a very broad particle size distribution combine to make the measurement of particles within a fluidised bed a significant challenge.
As part of a joint development project between Glatt Ingenieurtechnik, of Weimar, and Parsum, of Chemnitz, the use of inline particle size measurement was investigated under various operating conditions.
In tests involving the monitoring of lactose granulation, the Parsum probe tracked particle growth throughout the entire process, generating data that opens up options for automated control.
The Parsum is an optical rod probe with no moving elements that measures particle size by detecting interruptions of a laser beam as material passes through it. It is insensitive to vibration and slight impacts, and once installed - usually in pipelines, falling zones or vessels - it requires no manual adjustment.
An integral pressurised air feed ensures that the optical sapphire windows are protected from product build-up - a particularly important feature for potentially fouling applications. It is suitable for the measurement of particles from 50 to 4000µm at temperatures ranging from -20 to 100°C.