The horizontal cooler
The horizontal cooler has a “bed” of pellets resting on a perforated steel or solid pan moving belt which is slowly being passed through the cooling air stream. Its major advantage over the vertical cooler is that the horizontal cooler, with its moving bed, will mechanically move and discharge the pellets. This provides the positive flow action which is needed when processing pellets which, for some reason, may be prone to stick together. In a vertical cooler, pellets which are “sticky”, such as those with a high molasses content, are likely to be “glued” together during or due to the drying and cooling action, preventing their normal flow through the unit. These units are often found to be two high. The purpose is to conserve floor space by utilizing two short units rather than one unit which is twice as long.
The pellets normally flow by gravity into a device which spreads the pellets to a uniform bed depth across the belt. This spreading device can be an oscillating feeder or it can be a surge hopper with a discharge gate having a fixed opening to allow the belt to be filled with pellets to a specific depth. A level control on the inlet hopper is used to sense the accumulation of pellets, starting and stopping the cooling belt drive. This type of control is similar to the operating control on the vertical coolers. As the product is conveyed by the perforated belt, a suction fan draws cooling air through the air inlets which are holes cut into an airtight housing to direct the air to a point under the bed of pellets.
Air travels up through the bed and into the air plenum chamber and then to the fan and/or a “dust” recovery system. The length of the horizontal cooler and the speed of the belt drive determines the duration time of the cooling cycle. The width of the cooler and depth of the pellet bed determine the production rate (capacity). The depth of the bed, the width of the cooler, the size and length of air pipe, and the size and type of dust collection equipment determine the fan requirement.
Horizontal coolers are an alternative solution to the other cooling systems when vertical space is limited or when the product is presented in finely granular form.
| Advantages | Disadvantages |
|---|---|
| Requires little height | Complex mechanics requiring maintenance |
| Very high capacity | Cooling problems at the beginning and end of production |
| Can be used with many types of products |
La Meccanica’s horizontal coolers are equipped with:
- Cooling deck composed of trays made in stainless steel AISI 430 fixed on both side to high specification chains.
- Oscillating pellet distributor at the inlet made in stainless steel.
- Air aspiration hood made in stainless steel type 304
- Bin walls made of mild steel with mild steel reinforcements.
- Special scraper on the lower deck to collect the dust from the bottom to one side of the cooler.