- Heat pump based condensation drying for plastic packages
- Short drying times, high energy efficiency
- Gentle low temperature
Primary and secondary packages from plastics and other materials which have undergone cleaning, pasteurization or sterilization must be reliably dried for subsequent printing, labelling, final packaging or further processing. In order to avoid that drying becomes a bottleneck in production, a proven drying technology is worth considering: “heat pump based condensation drying”
Heat pump based condensation drying
The so-called Airgenex drying system was developed by Harter Oberflaechen- und Umwelttechnik, Stiefenhofen, Germany, more than twenty years ago to be used in the plating industry and has found hundreds of applications in various industries. The pharmaceutical industry identified this technology some years ago to improve drying quality and optimize processes. The food industry has also increasingly profited from this gentle, low temperature drying method. And the technology has also entered the plastics industry. The technology is characterized by short drying times, high process reliability and high energy efficiency.
Airgenex condensation drying is capable of drying any solid matter at low temperatures of between 20°C and 90°C, as required for each application. This is done by passing extremely dry and, thus, unsaturated air over the items to be dried to quickly absorb any humidity by physical action. In a downstream dehumidification process, the air is stripped of the humidity it carries. The humidity is condensed and the condensate drained off. Subsequently, the cooled air is reheated using recuperated energy and recirculated. The loop is closed. This makes the drying cycle almost emission free. The dehumidification module controlling the environmental conditions inside the drier is a component of the drying system. This drying system can be integrated in any process, no matter whether batch or continuous drying is required.
Adequate air routing
The company has identified two controlling factors for successful drying with the Airgenex condensation system: Firstly, high-tech dehumidification, as described above, is a must. Secondly, but not less important, the air recirculation system inside the drying chamber must be adjusted to exactly meet the requirements of the given process for the specific product. Failure to do so will reduce the performance of the powerful dehumidification module. The air recirculation system installed in the drying chamber is always purpose-built. The specific air volume inside the drying chamber is critical for high drying quality in short time. The essential factor here is air routing. The air must actually pass over or, if applicable, through rather than past the items to be dried. And as the air wants to take the path of least resistance, it must be forced to take the right path, an engineering effort which is one of company’s specialties.
Gentle low temperature
The drying temperature is critical, particularly for plastics. Examples are decorative parts for automobiles, bathroom facilities, household appliances, and also custom jewellery. Harter has already realized, for example, a station for drying plastic wraps for food packaging. For the pharmaceutical industry, drying and cooling after sterilization is an important issue. Good results may not be obtained unless a constant environment inside the drying chamber is ensured. Operating as a closed system, condensation drying is independent of seasonal or production induced temperature variations. Drying examples are infusion bags and bottles, but also lozenges or blister units after cleaning. In the food sector, the bottom fold of stand-up pouches is a great drying challenge. Exact air routeing is critical to dry its difficult geometry within shortest time. Other plastic products which may be condensation dried include coated optical glasses and spectacle frames.