Dryers for wooden chips
Wood drying is a key stage in the production process that ensures high quality calorific value of pellets. If the drying is not carried out to a sufficiently low humidity, then the pellet granules will not be well formed and would not burn efficiently, which, in addition to low energy efficiency, will also cause problems for the boiler equipment in which these wood pellets are used. Guaranteeing low moisture levels, while maintaining the amount of lignin in the feedstock, is a prerequisite for quality production.
4-zone cylindrical, rotary type
These dryers are designed to evenly dry larger quantities of wood. The wood particles are stage-dried in the compartments of the dryer, initially drying at the lowest speed. The flow of hot air passes through the center of the cylinder, with wood particles passing through it, falling from high. Each subsequent area of the machine has a smaller internal diameter and thus increases the drying rate. The dried particles pass forward under the influence of the air stream, and the moist ones, because of their greater weight, remain inside the system until they are completely dried. The dried particles exit the system without being too hot. The principle of operation of this type of dryer guarantees the same moisture values of different sized particles. This is especially important if the purpose is to dry wooden chips of larger particles.
The principle of operation of these dryers is the drying by warm air, of horizontally moving wood particles. The fans supply air which is heated by a heat generator. The airflow is adjusted to such speeds (depending on the size of the particles) that the raw material “hangs” in the air above the belt, overcoming the gravitational forces. At the same time, the wooden mass moves to the exit of the machine, where drying time varies between 30 and 120 seconds. Cold air is supplied at the end of the strip, which cools the raw material. At the same time, a cyclone (separator) and a filter connected to the dryer collect the dust from the recovery system. These types of dryers are suitable for drying smaller wooden particles.
Depending on the particle size, the particle density, the flow rate and the moisture content of the raw material at the inlet of the system, belt dryers are designed as a complex system.
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