Pilot Plant Technologies

Niro pilot-scale drying systems are offered in three basic designs:

• Spray Dryer Systems
• Vibro-Fluidizer® (Fluid Bed Dryer)
• Swirl Fluidizer™ (Flash Dryer)

Spray Dryer Systems

Spray drying is the transformation of liquid feed into a powder form by spraying the liquid into a hot drying medium inside a drying chamber in one continuous process. The dried powder will conform to single particles or agglomerates, depending on the physical and chemical composition of the liquid feed.

Dried powder particles, along with moisture-laden exhaust air from the drying chamber, are processed through cyclone separators or other separators to separate the powder from the exhaust air.

Three types of atomization are generally used:

• Rotary atomizer, where a product is continuously accelerated toward the edge of a wheel by centrifugal force. The liquid is discharged at high speed at the periphery of the wheel, resulting in very fine droplets.
• Two-fluid or pneumatic nozzle for producing very small particles, especially from viscous liquids.
• Pressure nozzle atomizer for uniform coarse particles.

Typical Applications

Spray drying is ideal for milk, infant formula, milk replacer/creamers, whey processing, and milk proteins.

Vibro-Fluidizer® (Fluid Bed Dryer)

The Vibro-Fluidizer® is especially suited for products that fluidize poorly due to broad particle size distribution and/or irregular particle shape.

The Vibro-Fluidizer® is a long horizontal box divided into upper and lower sections by a specially designed perforated air distributor plate. Fluid bed processing involves drying, cooling, agglomeration, granulation, and coating of particulate materials. It is ideal for a wide range of both heat-sensitive and non-heat-sensitive products.

For drying, alternatively for cooling, warm or cold air is introduced through the air plenum chambers in the lower section. The product is continuously fed into the perforated plate, forming a shallow fluidized powder layer. Product residence time depends on the product and fluidizing velocity.

Typical Applications

The Vibro-Fluidizer® is ideal for milk powder, cheese, lactose, whey, and high-fat products.

Swirl Fluidizer™ (Flash Dryer)

The Swirl Fluidizer™ is the best solution when viscous fluids, sludges, pastes and filter cakes must be converted to fine powder.

The heart of the drying process is a cylindrical drying chamber consisting of three important components: an air disperser, a rotating disintegrator, and a drying section.

The hot drying air enters the air disperser tangentially, and with the use of an advanced guide vane arrangement is introduced into the drying section as an intense, controlled swirling airflow. The rotating disintegrator is mounted at the base of the drying section. Under the influence of the disintegrator operation and swirling air flow, a feed comminution and drying process takes place, and the resulting dry fine particles pass out with the exhaust air for collection in a bag filter.

The disintegrator speed controls the degree of comminution, and hence particle size.

As the air residence time in the drying section is very short, typically 1-2 seconds, the Swirl Fluidizer™ is always a compact unit.

Typical Applications

The Swirl Fluidizer™ is ideal for starch.