Fluidized Bed Dryer New Fluidized Bed Dryer for Suspensions and Solutions Eliminates the Need for Grinding

Nowadays, the most common way to obtain extremely fine particles from suspensions is a combination of spray drying followed by a subsequent grinding process. The grinding step is necessary because the product from a spray dryer is in the form of an agglomerate. To avoid the need for this two-step process and so reduce equipment costs, Nara has developed a different type of dryer.

Related Vendors

Glatt Ingenieurtechnik GmbH

Italvacuum, Srl

Frewitt fabrique de machines SA

NARA Machinery Co. Ltd. Zweigndl. EUROPA

The new Media Slurry Dryer (MSD) generates an end product with particles of the same size as in the original suspension. For this purpose, the slurry is pumped from a holding vessel into a fluidized bed of inert media beads inside the drying tower, where the particles in the slurry disperse. They then adhere to and dry on the beads, before being carried out by the gas stream. The actual drying is done by hot gas which flows through the fluidized bed.

Typically, the drying gas is air taken from the surroundings by a fan, pre-filtered, heated and finally blown into the dryer. The hot air causes the beads to circulate, forming a fluidized bed with characteristically high rates of heat transfer. Thanks to the very large surface area of the media beads, moisture in the slurry quickly evaporates to the point that only solid material remains on the surface of the beads.

As the material dries, it adheres less strongly to the beads, and combined with the constant motion this results in small particles of product peeling away from the beads. The end product, in the form of a very fine powder, is subsequently entrained by the exhaust air and collected in a cyclone or bag filter.

Hazardous materials such as flammable solvents and explosive dusts may be safely processed in the closed system variant of the Media Slurry Dryer, which uses inert gas.

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