The vertical cooler
The vertical cooler is made up of two columns of pellets, side by side, held in position by wire mesh on both sides. Air is drawn through the column of pellets by means of a fan.
The pellets flow (usually by gravity) from the pellet mill to fill the columns and the hopper above the columns up to the level sensing device near the top of the funnel shaped hopper. Pellets resting in this hopper act as an air seal that forces the cooling air to pass through the column of pellets to reach the fan. When the amount of pellets in the hopper reaches the level sensing device it starts the discharge gate drive motor, which turns the discharge gates at the bottom of each column, thereby lowering the level of pellets in the cooler to accommodate the continuous flow of hot pellets from the pellet mill. While the flow of pellets through the columns is being automatically related to exactly the production rate of the pellet mill, the fan is drawing air through the columns of pellets into the air plenum chamber, discharging this feed dust laden air to a cyclone “dust” collector.
During a production run, an accumulation of feed dust may build up in the plenum chamber. Therefore, before the next run the dust accumulation should be cleaned out to prevent contamination.
The vertical cooler takes a minimal amount of floor space and it guarantees very good cooling efficiency.
Vertical coolers
| Advantages | Disadvantages |
|---|---|
| Takes up little floor space | Not suitable for very fine products or products containing a great deal of powder |
| Mechanics are quite simple | Limited capacity |
| Can damage the pellets |
La Meccanica’s vertical cooling group is composed by:
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A vertical cooler, that takes a minimal amount of floor space, but still with very good cooling efficiency.
It includes: inlet hopper made in stainless steel, complete with two product sensors; cooling module with lateral valves made in stainless steel, lateral inspection door and mild steel reinforcements; oscillating unloader.
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A vibrating sifter, that is a pellet cleaning machine with oscillating motion, which guarantees a high efficiency in dust separation. The body of the machine is made of sheet metal with large inspection doors, while the frame for the screening grids is made of wood.
The screening network is supplied with dimensions chosen by the customer. The frame is easily removable from the back of the shaker pre-dryer, oscillatory motion is transmitted to the shaker pre-dryer by means of an eccentric shaft.