Energy-Efficient Underwater Pelletizing
Thermally insulated die plates improve the energy balance during underwater pelletizing. The melt is maintained at temperature in the region of the die plate and cools only when it encounters the process water.
In the systems that have been employed to date for underwater pelletizing, the contact surfaces of the die plates are usually of hardmetal construction and exhibit a high thermal conductivity. Since they are firmly attached to the for the die plate carrier, they conduct large amounts of heat. This can result in “freezing” of individual die orifices during pelletizing. Loss of production, increased melt loss and additional expenses for cleaning and maintenance are the direct consequences.
The thermally insulated die plates available from Econ GmbH minimize loss of energy to the process water. The heat required for the die plate carrier is reduced by more than 70%. Since less heat is transferred to the process water, no additional energy is required to cool the water. According to information from Econ, annual cost savings are in the 4-figure range (Euros).
Not sensitive to variations in throughput
Even the pelletizer drive motor requires less energy. The plastic is softer when pelletized, so that less energy is required for cutting and the knives remain sharp longer. In a stable, gentle pelletizing process, a uniformly round pellet results. Because of the special design of the die plate, no bypass is needed in the process water circuit. This simplifies start-up and increases system availability.
The thermally insulated die plate is not sensitive to variations in throughput. A single die plate is suitable for throughputs ranging from 3 to 50 kg per orifice. Previously, this was possible only by using different die plates.