H3-SH-24B bipex coupling Helical gear units H3

Flender/Flender Gear Units/Helical gear units H3

can be used. Such dryers are limitedto foods that form porous bed (cut, granulated, pelleted, or naturally particulate foods). For vegetable or fruit drying, multiple conveyors (up to ve), one above the other, (Fig., can be used. The wet product is introduced onto the top conveyor and progresses downward from one conveyor to the next. Air circulation is usually combination of cross-ow and through-ow. nal drying step for some vegetables and fruits is oftenprovided in this type of dryer. Gradually, the conveyor dryers are replacing drying trays Fig. 5 Simple cocurrent tunnel dryer with partial air recirculation. Drying of Fruits, Vegetables, and Spices 6 Fig. 6 Diagram of multiple-conveyor dryer. in tunnels for fruit and vegetable pieces such as apples, carrots, onions, and potatoes (. Infrared, microwave, or radio frequency energy is sometimes additionally supplied to theproduct conveyed through the tunnel. The drying unit may operate under vacuum or atmo-spheric conditions. 3.2.4 Fluidized Bed Dryers Particles of fruits and vegetables (whole or diced) may be dried in uidized bed dryers (Fig. or several of their modications: vibrouidized, pulse uidized, or spouted beddryers (4,5,. The main advantage of this type of drying is its brevity as result ofhigh-intensity heat and mass transfer achieved through enhanced air turbulence in theuidized bed. Batch or continuous systems are typically used for the drying of food parti- cles in the range of 2 to 1 mm. Peas, beans, diced carrots, onions, and potatoes are typical vegetables dried in this type of dryer. If the particle size of the food covers widerange, uniform uidization of the product may be difcult. In such cases, mechanicallyor pneumatically (pulse uidization) induced vibration may overcome the problem. Thefrequency of the vibration is usually in the range 5 Hz with an amplitude of fewmillimeters (. This type of dryer is often used as second-stage powder dryer or as granulator after, for example,