Automotive textile manufacturer recovers major energy savings from compressor waste heat

Automotive textile manufacturer Autofil Worldwide has achieved average cost savings of £37,000 a year and reduced annual CO2 emissions by 260,000 tonnes by adopting Atlas Copco’s energy recovery technology.
Based in the UK, Autofil Worldwide is one of Europe’s leading manufacturers and suppliers of polyester yarns for the automotive sector. By recovering heat produced by the air compressor used in the manufacturing process, the company is able to raise the temperature of the process water it requires, which reduces overall energy usage.

The primary manufacturing operations at Autofil’s 10,000sq m UK plant require a substantial volume of compressed air, which is supplied via an Atlas Copco system. The system is controlled by an ES 360 optimiser, and comprises 12 compressors, including three GA 160+ units and a GA 250 compressor connected to a stand-alone ER-S5 energy recovery unit.

As well as the considerable demand for compressed air on site, the dyeing processing has an equally large requirement for process hot water. A 50,000 litre tank stores water for several dyeing process operations in the factory and the by-product heat from the GA 250 compressor is used to pre-heat this water to around 50°C, rather than relying on additional gas power to heat it at point of use.

This is made possible by the ER-S5 energy recovery unit, whereby hot oil from the compressor’s air end is diverted through a stainless steel plate heat exchanger. Heat from the oil is transferred to cool water on the opposite side of the exchanger, producing a continuous flow of hot water from the ER outlet.

The water circuit between the tank and ER unit takes cooler water and replaces it with the heated water. After a few hours, this circuit reaches its optimum inlet/outlet temperature: inlet water from the top of the tank to the ER at +/- 30°C; outlet water fed back from the ER to the bottom of the tank at +/-55°C, achieving a temperature rise of 25°C.

Based on the compressor running for 8,424 hours per year, the combination of the GA 250 and ER-S5 unit is recovering more than 1.4 million KWh of energy a year. The savings are self-evident: to increase the temperature of the same amount of water with a gas-fuelled heating source would have cost Autofil £37,096 annually and would have generated 260,000 tonnes of CO2.