Hot air dryers are essential in the plastic processing industry. Effective drying of plastic granules ensures that businesses in this sector have completely dry materials for use in processing stages, thereby guaranteeing the quality of the final product. In this article, we will explore what hot air dryers are, how they work and what advantages they offer. We will explain the differences between drying and dehumidification and present the technical solutions and advantages offered by Vismec air dryers.
What a hot-air dryer is and how it works
A hot air dryer is a device designed to remove surface moisture from plastic granules by using heated air. Below are the detailed process steps.
- Heating the air. The air is heated using electric heating elements or other heating systems. As we are going to see in more detail in the last paragraph, in the case of Vismec dryers, specific systems control the air temperature very precisely.
- Hot air circulation. Hot air flows through the hopper, absorbing surface moisture present on the plastic granules. This process is particularly effective for non-hygroscopic polymers, which do not retain moisture within their structure.
- Expulsion or recirculation of moist air. In particular, in open-circuit systems, moist air is expelled and replaced with fresh air. In total or partial recirculation systems, on the other hand, moist air is filtered, reheated and reused, reducing energy consumption.
- Control and regulation. The air flow rate can be adjusted manually or automatically to suit specific operating requirements. Advanced models, such as those from Vismec, include smart mode management functions and temperature probes to optimise energy efficiency.
These steps, when conducted efficiently, ensure a perfect drying of the granules while minimising residual moisture. In this way, plastics processors can have completely dried polymers, guaranteeing the quality of the final product. The drying cycle can also be continuous, ensuring a constant flow of dry granules to the machinery.
Drying and dehumidification: differences
Although they are often used synonymously, drying and dehumidification are two distinct processes.
- Drying refers to the removal of surface moisture from materials: a process suitable for non-hygroscopic polymers that, as mentioned, do not absorb moisture from their surroundings. In other words, these polymers do not significantly change their physical and chemical properties when exposed to moisture or water. This makes them different from hygroscopic polymers, which instead tend to absorb moisture, altering their structure and behaviour.
- Dehumidification, on the other hand, applies to hygroscopic materials that absorb moisture from the environment, such as PET. This dessication process uses more advanced and structured technologies.
With regard to this last point, the wheel dehumidifiers that our company designs and manufactures have an internal rotor to dehumidify the granule. However, in dryers, this element is omitted.
In various industrial contexts, both drying and dehumidification prepare the plastic granules for optimal processing. This condition, as we have already seen in previous articles, is particularly important in processes such as moulding or extrusion, or in sectors such as the electronics industry and the medical or food industries, which require perfectly dry granules to meet high quality standards.
Vismec air dryers: features and advantages
Vismec hot air dryers are designed to remove surface moisture from non-hygroscopic polymers. Combined with an adsorption dehumidifier, they can also handle highly moist hygroscopic polymers.
Key features of our dryers include:
- Variable air flow. Vismec dryers are equipped with a system that allows the air flow rate to be adjusted according to operational requirements, optimising consumption.
- Energy optimisation is achieved through smart mode management, a return air temperature probe, and a PID algorithm, which maintains a constant and precise air temperature during the process, ensuring uniform drying.
- High-efficiency blowers. The smaller models use brushless blowers, while the larger versions are equipped with IE2/3 motors and inverters, ensuring efficiency and durability.
- Advanced technology. The AG models have a 7-inch touchscreen control and a valve to manage recirculation, eliminating the need for cooling.
Vismec hot air dryers offer a number of advantages, thanks to their advanced technical features.
- Continuous drying process, for an uninterrupted workflow that maintains high productivity.
- Adaptability and energy savings. The internal devices we have described in detail allow the dryer to be adapted to specific needs, optimising energy consumption.
- Ease of use. Touch screen controls and remote monitoring options make Vismec dryers easy to operate and manage, improving operational efficiency.
Our hot air dryers offer flexible installation options, either mounted on machinery or placed next to moulding or extrusion equipment.
Looking for a high-performance hot air dryer for your plastic processing needs? Contact us to find the ideal solution for your business.