Reactor drying is a new technology, combining rapid heating of the PET with an innovative control of the residual moisture of the resin. In the late 1980s and early 1990s, Piovan was a supplier of small-scale vertical tower solid- state polycondensation (SSP) systems, and this allowed it to learn in depth about the physical phenomenon taking place in the vertical tower – the reactor – while rapidly increasing the polymer temperature. SSP takes place at temperatures of 220°C, in the absence of oxygen.
GenesysR operates at regular drying temperatures (170–180°C) in a dried-air environment. Unlike SSP, it does not increase intrinsic viscosity (IV), and can reduce drying time from seven hours to five. Energy efficiency is improved by 10W-h/kg, ensuring savings in the range of 60% and beyond compared with a conventional drying system. Piovan holds the only patent ever released for “high-efficiency system for dehumidifying and/or drying plastic materials”, dated 29 May 2013, EP2186613B1.
The GenesysR line’s low energy use and high stability makes it ideal for high-productivity applications. It benefits from an innovative control of the residual moisture in the PET, namely Automatic Injection Pressure Control (AIPC, a patent-pending technology). Any GenesysR system can be connected to the preform injection moulding machine and, by reading the injection pressure in real time, can stabilise it to the desired value.
A new algorithm specifically developed for the AIPC can constantly adjust airflow, temperature and dew-point of the process air, so that the injection pressure is kept at the highest possible level of constancy. This is particularly valuable today, as the new preform formats require thinner walls and therefore controlled conditions of moisture and injection pressure.
GenesysR is the only auto-adaptive drying system capable of determining a condition of energy balance in the PET resin between drying and injection.
Energy balance is crucial for the production of a preform, because of the physical and mechanical characteristics of the bottle.
The best processing condition for PET resin is obtained when the lowest possible temperature increase or energy addition is performed by the injection unit or extruder.
GenesysR is capable of measuring the quantity of energy released to the PET. The energy addition at the injection unit is a critical parameter, as it determines the IV drop of the PET: the lower the energy addition, the lower the IV drop.
The auto-adaptability feature of GenesysR therefore offers two key advantages to the bottle: highest IV of the PET, obtained by the energy balance capability; and lowest acetaldehyde (AA) level, obtained by the AIPC feature.
Auto- adaptability also allows the use of multiple grades of PET, from different suppliers and produced in different processes.