Common categories of plastic drying equipment
1. Hot Air Dryer: This is a more traditional and common type. Its principle is to use an electric heater to heat the air, and then a fan sends the hot air into a sealed drying hopper to circulate and heat the plastic granules. The hot air removes moisture from the surface of the plastic, making it damp. The damp air then passes through a dehumidification system (which may be a simple exhaust system or include more complex devices) to remove the moisture. This cycle continues until the plastic reaches the required dryness. This type of equipment has a relatively simple structure and low initial investment cost, making it suitable for various general-purpose plastics with less stringent drying requirements.
2. Dehumidifying Dryer: In high-altitude areas or during humid seasons, the ambient air humidity is already high, making hot air drying inefficient and with limited effect. In these situations, dehumidifying dryers are more efficient. Their core feature is the addition of a dehumidification module (usually using molecular sieve or rotary dehumidification technology). This module first deeply dehumidifies the air used for drying, significantly lowering its dew point temperature and making it very dry, before heating this dry air to process the plastic. This "dehumidify first, then heat" method can more thoroughly remove moisture from the inside of plastics, making it particularly suitable for engineering plastics that are highly hygroscopic, such as nylon (PA), polycarbonate (PC), and polyester (PET).
3. Vacuum Dryer: This is a device that lowers the boiling point of water by creating a vacuum in a sealed container, thus allowing the moisture to evaporate rapidly at a lower temperature. Its innovative advantage is that because the drying temperature can be controlled at a lower level, it can effectively prevent oxidation or degradation of certain heat-sensitive plastics during the drying process. The drying speed is also faster in a vacuum environment. For some special high-performance plastics or applications with extremely strict requirements on residual moisture, vacuum drying is a good choice.
