The better is the enemy of the good – NitroHotfill and compressed-air savings

I presume I’m not telling most of you anything new when I write here that in order to blow-mould PET bottles you need compressed air. Things get more specific when you want to produce PET bottles that can be hot-filled– as is necessary, for instance, to enable the product shelf-life of juice or tea to be guaranteed. Hot-fillable bottles need a higher weight in order to withstand the more severe stresses involved. For producing them, too, more heat is required in the mould in order to render the bottle thermally stable. In order to remove this additional heat again by cooling (with what is called “flushing air”), more compressed air is consequently required – and the process costs rise with the increased energy consumption, since compressed air costs energy. In order to meet and master this challenge, we produced our first NitroHotfill bottle back in 2008. What’s so special about it?

With the NitroHotfill process, you save a whole lot of PET material and air compared to a conventional hotfill process – which cuts your costs as well. The former, because the bottle doesn’t have to withstand a vacuum after being cooled down: there is a small nitrogen overpressure remaining in the bottle, you see, which stabilises it. This enables lighter containers to be used, which then don’t need to be blow-moulded at quite so high a temperature, thus saving very substantial quantities of flushing air.

So with NitroHotfill, you save significantly more energy, economise on resources, and render your operation more affordably cost-efficient.

Our Turkish client Dogus Cay produces around 35,000 tons of tea a year at five facilities in Rize, plus a packaging plant in Ordu. The black tea from the coasts of the Black Sea, with its distinctive taste, is distributed all over Turkey.

In 2015, Dogus Cay commissioned a NitroHotfill line at its facility in Izmir/Ödemiş rated at 22,500 containers per hour. The Krones Contiform 3 blow-moulder produces the containers for top-quality ice-teas. It utilises ten moulds, each with a record output of 2,250 containers per hour, creating hotfill PET containers with a volume of 250 millilitres, and nonetheless weighing a mere 15 grams. A line than as soon as it was installed scores highly in terms of low energy and resource consumption. At Krones, though, development work doesn’t cease after commissioning. One year after installation, a Krones team carried out on-site trials at the line for improving the compressed-air system. Following an upgrade and a simple optimisation job on the Contiform 3, the line went back into normal operation. A test run achieved extraordinary results: with identically good container quality, the upgrade produced savings in compressed-air consumption of 44 per cent – more than 300 Nm³/h. Future savings may even be higher than this if larger containers are used in the months ahead. The crucial point for the client was this: the upgrade saves real money: around 40,000 euros a year given a calculated machine running time of 6,000 hours per annum.

A cogent example, which shows when you choose Krones you’re buying more than just a line. Our clients are not cut off from progress even after commissioning, and continue to benefit from the support and expertise of Krones AG.