The demands on the quality of seeds have increased over the last number of years, and the drying of the seeds has become ever more crucial for the viability of the seed. In addition to purity and germination, the appearance and homogeneity of coating over the seeds as well as the dust-off value, moisture level is a very important factor.
The continuous increase of the quantity of applied chemicals, including the fungicides, insecticides, water and polymers, during the treatment process leads to an increase in the moisture content of up to five per cent. The new fluidized bed dryer has been designed to accomplish the chemical treatment of seeds as a post-drying process. In practice, we found that the applied fluidized bed dryer improves the coating quality and appearance as well as maintains the flowability of the seeds before the packaging process.
This specific dryer is so special because it has a unique Z-shape with optimal fluidization. That secures a gentle flow through the dryer. This Z-shape reduces the footprint and the volume, increases the screen area/m² and is responsible for very flexible operations such as a continuous, batch or semi-batch load as well as variable temperature regimes over the two levels. In addition, the zigzag product flow turns over the product when it goes from level one to level two. This increases the mixing effect.
This mixing/turn-over effect was tested by feeding the dryer with red and non-colored seed in an alternate manner. At the end, the different colored sections were fully mixed. The dryer is supplied with a full control box, which makes the adjustment of the drying process easier with the possibility of saving the different parameters in recipes.
The benefit of using such a post-treatment dryer is that it decreases the dust-off value, improves the flow-ability and sow-ability, and finally gives an added value to the seed before packaging. The unique design of this dryer and the flexibility of the operation lets the application of the dryer converge a wide range in seed processing from maize and soya down to grass seeds. In fact, a broad number of seed companies would find a good use for such a dryer.
—Khaled Raed is innovation manager for PETKUS Technologie GmbH