Fluid Bed Dryer

Click here to download spec for Model M501 Programmable Fluid Bed Dryer.

The Sherwood laboratory fluid bed dryer has a number of advantages over conventional oven drying - a wide range of materials can be uniformly dried, including pharmaceuticals and foods. Quick , reproducible, homogeneous drying without hot spots or wet spots! In a fluidised bed, a particulate sample becomes liquid-like when a gas is forced through it. The gas breaks down into small bubbles as it passes through the solid, resulting in a very high gas/solid surface contact and the solid is extremely well mixed in the process. The mass takes on the appearance of vigorously boiling soup. Fluidisation, when applied to drying the solid being fluidised, gives several advantages.  In spite of its appearance, the process achieves a very mild form of drying, since the large mass transfer of air (2 to 3 cubic metres per minute) allows the sample to dry at low temperatures and the particles are cushioned by air bubbles, making the mixing non-abrasive. The drying times are very quick, typically 15 to 20 minutes for a 2kg sample of material. The end result is a homogeneous sample of material without agglomerates. The material (maximum sample size 5kg) is placed into a tub (glass or stainless steel) and a terylene, nylon or polypropylene filter bag is placed over the top to prevent material being blown out of the drying zone. Air is blown by a centrifugal fan over a 2kW finned electrical heater and temperature control within the fluidised bed is facilitated by a thermocouple in conjunction with a 2-term analogue controller. Timed drying (up to 6 hours, in six ranges) or continuous drying can be carried out and a built in timer allows the unit to be left unattended. At the end of the cycle, an alarm sounds and the dryer switches off automatically. When drying difficult, flakey or non-spherical samples (which easily compact) an optional 'pulse flow' feature can be fitted to the fluid bed dryer.

We have an ex-demonstration digital base unit, in reasonable condition, available for sale, model 26/FBD1311 220v model, together with an ex-demonstration 2-litre glass tub and base.