PET hotfill option

With its NitroHotfill process, Krones AG is offering an alternative to conventional hotfill processes.

Krones’ in-house expertise in bottle design and stretch blow-moulding technology has now enabled a concept familiar from other applications to be used for a PET hotfill process as well. Process control is based on the ‘Relax-Cooling’ (RC) concept, where the installation of a nitrogen injection dosing feature just before the capper creates a positive pressure of 1.5 to 2 bar inside the bottle. The positive bottle pressure compensates for the shrinkage in product volume downstream of the re-cooler, thus preventing any bottle deformation due to under-pressure.

This means the panel design previously required to compensate for the vacuum pressure with hot-filled products can be dispensed with. The process can be utilised for the bottle production process in the Contiform H, which also enables aluminium moulds to be used, and reduces the machine’s air consumption.

The Krones NitroHotfill technology scores in terms of material savings with the PET bottle itself, with reduced blow-air consumption, enhanced performance in the stretch blow-moulding process, and increased output from the line as a whole. Depending on the preform and bottle material being used, and the differing as-is parameters like filling temperature, bottle shape and stipulations for bottle design and closure, material savings of up to 30% have been claimed.

The RC technology also enables the Contiform H’s flushing air consumption to be reduced. This is the result of a small flow rate and a shorter flushing time. Air recycling with the Air Wizard IV helps to reduce air consumption still further.

The NitroHotfill process offers an affordable option for a PET hotfill process. The major pluses are its beneficial effects on operating costs and the price per bottle. The option for producing their own hot fill containers in house makes bottlers more independent and flexible.