Designing of the dryer section of nutritional yeast production plant – Industrial sector review – Part 17

Designing of the dryer section of nutritional yeast production plant – Industrial sector review – Part 17

Atomization of feed

It is necessary to dispense and distribute the cream under control conditions, which is done by the atomizer. Generally the atomizers are divided into two sub division, namely (1) Rotary and (2) Nozzle atomizers. The selection
and operation of the atomizer is of supreme importance in achieving economic production of top quality products. The atomization stage must create a spray for optimum evaporation condition leading to a dried product of required characteristics. The selection
of the atomizer used in the process is discussed in chapter 3. The atomizer to be used in processing the cream is the rotary atomizer (spinning wheel).

Application of atomizer wheels are found in many industries, including ceramics, dairy products, foodstuff, and pharmaceuticals.  Feed liquids, slurries and pastes having heat sensitive properties can be successfully atomized
using atomizer wheels (Masters, 1979)

The degree of spray distribution depends on the wheel speed, feed rate, liquid properties and atomizer design. Maximum centrifugal energy is imparted to the liquid when the liquid acquires the speed of the rotating disc. At
low feed rates and low rotating speed the atomization takes place by direct droplet formation (viscous and surface-tension forces predominates). For intermediate speeds, the disintegration of the liquid extending out of the vane is by centrifugal force (Jin-Sung,
2001). At normal condition i.e. at high feed and wheel speeds, near 10 000 r.p.m, the liquid disintegration occurs right at the wheel edge by friction effects between air and liquid surface as the liquid emerges as a thin film from the vane. Increased amounts
of energy available for liquid atomization results in spray having smaller droplet size

Continued in part 18

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Posted by Ahmed Tariq on Feb 29 2012. Filed under Sci-Tech. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry