One method for producing and drying granulates is the fluidized bed process. A uniform stream of air is fed up through a distributor plate at the bottom of the fluidized bed reactor. A liquid granule suspension is sprayed in from above, in the air stream it turns into solid granulate and collects on the top of distributor plate and the exhaust air flows through a filter for cleaning. To ensure a high-quality process, both the granulate quantity on the distributor plate and the condition of the filter must be permanently monitored. The measurement technology must also fulfil the most stringent hygienic requirements in order to guarantee a consistently high granulate quality.