Johan Gorter, CEO, Glass, Europe Ardagh Group said when it is delivered to the glass plant, cullet is typically stored in outdoor bunkers, where it is subject to climate conditions, particularly during winter months. If it has accumulated significant levels of water, snow and ice, it requires higher temperatures, and more energy, to remelt it in the furnace.
The latest project was to find a simple way of pre-heating ‘frozen’ cullet prior to feeding it into the furnace. But because a traditional preconditioning process can use a lot of energy, an alternative approach of capturing heat already generated elsewhere in the plant was sought.
“This is one of many planned actions we are taking throughout our European plants as we strive to meet the very highest sustainability performance standards,” said Gorter.
Investigations showed the most likely source of waste heat was around the furnaces. The challenge was to find the best way of recovering and transporting this hot air to the cullet. It was met by drawing hot air at 80°C across the furnace, blowing it into a specially developed heat exchanger charged with energy to raise the temperature to 120°C and piping it to the bunkers.