Spray Drier & Spray Driers

Niro specialises in industrial spray drying and agglomeration. We have supplied the most industrial drying plants in operation today. All systems comply with sanitary standards and are capable of being cleaned in place.

The spray driers below are the most commonly used in the food and dairy industry.

A spray drier layout featuring either a rotary atomizer or spray nozzle atomizer.

Conventional Two-Stage Drier

Powder discharged from the drying chamber can be further dried and cooled in a vibrating fluid bed, Vibro-Fluidizer®. This two-stage drying concept achieves better overall heat economy and is suitable for many food and dairy products. When non-agglomerated powders of non-fat products are dried, a pneumatic transport system can replace the fluid bed.

Two Stage and Multiple-Stage Spray Driers

Although one stage spray drier still represent the majority of spray driers in industrial operation, the constant demand for improved product quality (improved free flowability, dispersibility, lower dust content etc), more lenient product handling, highest possible thermal and operational efficiency while giving greater attention to environmental issues has brought about the need for further treatment of two and three-stage driers (multiple stage concepts). Furthermore, as the list of product applications lengthens and more complex products are handled and, at the same time dried product specifications become more stringent, it is more difficult to dry successfully in a one-stage layout. When such circumstances arise, the answer often lies in a two stage or multiple stage layout, where spray driers are combined with a fluid bed or paddle/screw mixers acting as after-driers or coolers or even microwave driers for final moisture content adjustment.

The attached fluid bed can be either a stationary type (backmix or plug flow design), or a vibrated type (plug flow design).

The stationary plug flow fluid bed design is suitable for products that are directly fluidizable on leaving the drying chamber. The stationary back-mix design is better for handling products that fluidize poorly due to their particle size distribution, shape and moisture content or only become fluidizable after a short time in the fluidizing layer when the moisture content level has been lowered. Stationary designs operate with deeper fluidised powder layers.

The vibrated fluid bed design is suitable for products that are more difficult to fluidise due to their (a) very particle-size distribution, (b) fine particle size, (c) irregular shaped non particulate form (fibre/crystal structure), (d) particle stickiness/surface softness causing lumping, or (e) where lenient powder handling is required to limit particle attrition effects by being able to operate the fluid bed at lower fluidizing velocities. Vibrating the fluid bed acts to move the particles away from the air distributor plate surface, provide forward particle movement to the product discharge area, creating a self-emptying capability on plant shut down. Vibrated fluid beds operate with shallow powder layers and simulate product plug flow movement. However with the development of air distributor plates for fluid beds that give directional control over particle movement, the need for strongly vibrated systems are no longer necessary to achieve powder flow through the fluid bed. This further enhances lenient product handling. There are four situations where a two-stage system with spray drying chamber and fluid bed attachment can be are used to advantage:

Fluidised Spray Drier

Agglomerated powders are obtained in systems based upon the integrated fluid bed or belt and a multi-stage concept where moist powder, produced during the first drying stage, forms agglomerates, which are after-dried and cooled in the following stages.

Fluidised Spray Drier FSD (Chemical) / Multi-Stage Drier MSD™ (Dairy)

The Fluidised Spray Drier FSD™ and the Multi Stage Drier MSD™ combine spray drying and fluid bed drying technologies and offer excellent product flexibility and excellent thermal efficiency.

Pressure nozzles or a rotary atomiser spray the feed down towards the fluid bed where agglomeration incorporating finer, recycled material takes place. Exhaust air outlet is let through the roof causing further agglomeration in the spray zone.

Sticky products can successfully be dried, and the concept is ideal for drying heat sensitive products, and improved aroma retention is accomplished.

Product: Agglomerated (instant), free-flowing dustless powders.

Tall Form Drier (TFD™)

The atomized droplets dry while gently falling down the tower. Further drying and cooling are carried out in a vibrating fluid bed located under the tower. The Tall Form Drier (TFD™) is suited for both non-fat and fat-containing products, producing non-agglomerated and agglomerated free-flowing powders.

Multi-Stage Drier (MSD™)

The spray is created by a spray nozzle atomizer. Operational flexibility enables production of a wide range of physical properties. The process produces non-dusty, free flowing agglomerated powders with high flavour retention. It operates with low outlet-temperatures, achieving high thermal efficiency. Dry ingredients for additional flavour or nutrient fortification can be added within the system to further promote capabilities and improve formulation efficiencies. This design concept is successful for drying high fats, hygroscopic, and sticky products that are difficult to handle in more conventional designs.

A tower spray drier (tall form drier) with a top mounted nozzle assembly featuring a fines return capability.

A spray drier with integrated fluid bed.

A spray drier with an integrated belt

FILTERMAT® Spray Drier / Belt Drier

The FILTERMAT® Spray Drier / Belt Drier is frequently used in food and dairy applications. It operates at a low oulet temperature, achieving high thermal efficiency. It is the recommended system for drying high fat, sugar-based, hydrolyzed, and fermented products. FILTERMAT® Specifications.

Compact Drier

Atomization is created by either a rotary atomizer or spray nozzle atomiser. The location of the fluid bed within the drying chamber permits drying to be achieved at lower temperature levels resulting in higher thermal efficiencies and cooler conditions for powder handling. The plant can be equipped with pneumatic transport system for many powders or with an external vibrating fluid bed for agglomerated powders.