DRYERS-tunnel-belt-continuous, semi-continuous

TUNNEL DRYERS

Tunnel dryers are very common in dehydrating food. They can be configured in parallel and against the current, the first being the mildest for the product while, in the second, the contact of the warmest air with the dry product hardens the surface. They can reach up to 24 m in length and consist of a cabin in which there is a rail mechanism which moves cars with products along it. The process is then semi-continuous.

BELT DRYER

In this type, the movement of the product is done by a conveyor belt. The most common configuration is that of the transverse air flow.

Continuous tunnel dryers

dryer

This type of dryer is formed by a tunnel, through which trays or carriages pass with the material to be dried, inside the tunnel, it circulates, generally against the current, hot air, which is used to dry solids. This type of dryer is typical of the food industry

Continuous tunnel dryers are usually tray or truck compartments that operate in series. The solids are placed on trays or trolleys that move continuously through a tunnel with hot gases that pass over the surface of each tray. The hot air flow can be countercurrent, in parallel, or a combination of both. Many foods are dried by this procedure.

When it is desired to dry solid granular particles, perforated or sieve bottom conveyors can be used. The wet granular solids are transported in the form of a layer that is 25 to 150 mm deep, on a sieve or perforated surface through which the passage of hot air is forced, either up or down.

The dryer made of several sections in series, each with a fan and heating coils. An additional fan draws a certain amount of air into the atmosphere. In some cases, pulp-shaped materials can be preformed into cylinders and placed on the conveyor to dry.

Semi-continuous tunnel dryer

This is the most traditional way to produce blocks, bricks, tiles and all kinds of hollow bricks.

  

The best technique for this dryer clays need precise air treatments, automatically handling all pressures, temperatures and humidity.

This dryer works with large masses inside, and for this reason, having a long drying cycle, does not stress the material minimizing the percentage of waste.