Dryers_-_Pneumatic_Ring_Continuous

Pneumatic Ring Driers – Continuous, Solid, Heat Sensitive

Industry: Fruit and Vegetable Preserving and Specialty Food Mfg (NAICS 3114)

NAICS process:

311411 Frozen Fruit and Vegetables

311412 Frozen Specialties

311421 Canned Fruit and Vegetables

311422 Canned Specialty Products

311423 Dried and Dehydrated Products

Process Brief: Moisture in fruits and vegetables is removed using hot air.

Energy source: Steam/Natural gas

Energy Intensity:

Pneumatic ring driers produce dried gravy and soup mixes, starches, and dehydrated mashed potatoes. Typically, the incoming product is less than 40% water. Most pneumatic driers use a vertical column of hot air that keeps the product in suspension as it dries. As the product loses moisture, it is more easily entrained and is recirculated through a ring that returns the product to the air column for additional drying. The velocity and temperature of the air flow determine the drying rate and management of the recirculation of the product determines its final moisture level. High temperature driers with short retention times are useful for expanding the starch in dried carrots and potato flakes. This expanded starch is an important part of the rehydration function of the finished product.

Pneumatic ring driers can dry products in less than ten seconds and are sometimes called flash driers. The units have relatively low capital costs and fast drying times which makes them desirable technology. Production rates for modern units can be as high as 25 tons per hour. The hot air can come from direct combustion of natural gas or, more commonly, indirect heating from steam tubes.

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