GENERAL FEATURES:

NOTE: The Crown Iron Works Aspirators are primary used in processing soybeans, but can be used for various applications and many different products. The basic function of the aspirator remains the same and for this reason soybean processing will be used in this manual.

In the preparation of oil seeds (soybean...) for oil extraction the bean needs to be cleaned and conditioned to the correct temperature and moisture. Also, the hull (outer shell) needs to be removed from the bean to increase the protein content of the meal. The Crown aspirator is designed to remove loose hulls and foreign material as well to heat or cool the bean.

The basic principle of operation is as follows: The bean enters the aspirator through a rotary feeder (whole bean or cracked bean). The bean cascades through the aspirator impact rods splitting and distributing the product flow allowing the air to pass upward through the falling bean loosening and removing the hulls. The air traveling through the aspirator is recycled through a cyclone via a fan to separate the hulls and dust from the air. The amount of ambient air (some times heated) added to the aspiration loop determines how efficient the process is and aid in the conditioning of the beans.

COMPONENT DESCRIPTION:

The Crown Aspirator uses a closed recycle air loop, consisting of a fan, cyclone, three air dampers and air heater (as needed). Note: The smaller aspirators may not use recycled air loops.

The aspirator assembly consists of three sections, the top inlet rotary feeder / drive assembly, the bottom main aspiration assembly and the air seal.

The top section consists of a inlet rotary feeder. This is a pocket or vane type feeder with an adjustable rotor clearance plate and gate which allows the aspirator to be choke fed and will accommodate multiple size seeds and the outlet air duct.

The bottom aspiration assembly consists of a bundle of impact rods, inspection / access doors, sample doors, sight glasses and the inlet air duct.

The air seals have bolted flange connections and weighted adjustable air seals.

The beans are fed into the aspirator through the inlet rotary feeder, which are distributed across the full width of the aspirator. The rotary feeder is designed to be operated choke fed which ensures the even distribution of beans. When the beans are distributed across the width of the aspirator prior to entering the feeder choke feeding is not necessary.

The beans cascade through the aspirator coming in contact with impact rods and counter-flow air. The counter-flow air enters form the bottom of the aspirator and exits the top of the aspirator. This air can be heated to maintain temperature and aid in the conditioning of the beans. The beans enter from top the aspirator and exit at the bottom of the aspirator, thus making it a counter current unit. The impact rods together with the counter-flow air, distributes the free falling beans throughout the aspirator. The impacting of the falling beans onto the fixed rods continually loosens the hulls from the beans or cracked beans as the counter-flowing air, airlifts the hulls up and out of the aspirator. The manner in which beans / cracks continually strike the impact rods randomly, keeps the air from ever being able to channel or separate from the material flow, ensuring maximum air to material contact resulting in excellent dehulling.

The air seal ensures that the inlet airflow into the aspirator enters only through the inlet air duct and not through the product discharge conveyor. The Crown aspirator uses a closed or recycled air loop, allowing the humidity and temperature of the air to be easily maintained. Resulting in good drying and conditioning, and reducing the amount of air being exhausted to atmosphere.

Click here for cascade aspirator equipment brochure.