Waste heat warms local college
16 Jun 2014
Greiner Packaging’s production plant in Northern Ireland is helping a neighbouring college cut its £40,000 annual heating bill by donating waste heat from its compressors and its process cooling installation.
Dungannon Integrated College, a secondary school with 500 pupils, receives the heat into its central heating system via underground pipework, which reduces costs and saves 200 metric tons of CO2.
Greiner Packaging, which is based in Austria, specialises in the production of rigid packaging containers supplied to the food industry in UK and Ireland.
Compressed air is used in all of the company’s production processes and is supplied by Atlas Copco oil-free, watercooled Z-range compressors – with their outputs optimised by a central controller.
It is the compressors’ water-cooling systems that provide the waste heat supply to the nearby school.
Air drawn into a compressor contains water vapour. Heat stored in the vapour is released through condensation in the inter- and aftercooler of the compressor.
The condensation heat contained in the input air is equivalent to 5-20% of the electrical input energy.
The design of Atlas Copco’s Z-range of oil-free screw compressors enables energy recovery capability, and the total energy recovered as hot water can amount to as much as 80-100% of the electrical input energy, depending on the site conditions.
This supply is combined with hot water from a large battery of cooling fans that assist the cooling cycle that is integral to the plastic forming processes undertaken at the plant.
“The rapid sequence of heating and forming plastic materials requires equally fast cooling of the molten polymers,” says Jonathan Parr, electrical services and plant manager at the site.
“We achieve this with a large battery of condenser cooling fan units, in addition to the water cooling systems on the compressors, which extract the heat in the form of hot water at 80 degrees Celsius, which is then delivered to the neighbouring school via 275 metres of pipework buried a metre underground.”
The community project, considered to be the first of its type, is reported to have cost Greiner Packaging £90,000, which was matched by funding from the Department of Education.
“It’s a project that shows recycling, it shows an environmental responsibility and it shows social responsibility,” says a department spokesman.
