Two regulated-speed compressors from Compair have helped Astrum, a steel components manufacturer, to cut its compressed air energy costs by more than a half and increase productivity at its foundry in County Durham.

Astrum was also able to benefit from an interest-free loan from the Carbon Trust to fund the installation, thanks to the high energy efficiency of its new compressed air system.

Based in Stanhope, County Durham, Astrum is a specialist steel foundry making components and assemblies for military fighting vehicles, ground engaging tools for the construction industry and wear parts for the mining industry. In 2008, due to rising energy prices, Astrum embarked on a programme of improving the energy efficiency of its processes.

Mike Hutchinson, operations director at Astrum explains: “One of our key areas of spend is our compressed air system, which is critical to the performance of our plant and is fundamental to our processes for moving sand around the foundry and for operating industrial equipment. As part of our programme of improving the energy efficiency of our processes, we looked to replace existing compressors and approached CompAir distributor, Air Energy Management to assess our air requirements.”

Working alongside Astrum and CompAir, Air Energy Management developed a bespoke system to reduce the demand on compressed air at the foundry, and replaced old, large compressors with two more efficient, smaller CompAir compressors.

The CompAir L75 RS and L160 RS compressors both feature regulated-speed technology and are protected and monitored by a Delcos 3100 electronic control system. Both compressors are linked to a flow measuring system, allowing operators to check airflow, allocate costs to different departments and pinpoint any leakage. In addition to compressors, CompAir also supplied energy efficient thermal mass refrigerant and desiccant dryers.

The new system will reduce Astrum’s compressed air energy demand by 1,255,000 kWh and save more than £80,000 a year.

A CompAir L75 RS regulated-speed compressor is located in a small compressor house at the foundry and provides air at 7.5 bar to a bore blast machine for optimum surface quality. The L75 RS’s regulated-speed drive technology matches compressor flow to plant demand. This means the unit produces the correct volume of air required by the application at all times.

CompAir overhauled an existing compressor to provide system redundancy. Previously, Astrum did not have any backup, meaning that if a compressor stopped working, production would stop.

Hot air venting from the small compressor house ensures that 80 per cent of the energy lost in the compression process is reclaimed. The hot air is ducted into the foundry during winter and out into the atmosphere in the summer, allowing Astrum to turn off heaters, saving £10,000 per year in diesel costs. The second CompAir compressor, an L160 RS regulated-speed unit with Delcos 3100 controller, is located in one of the main compressor houses. Working alongside overhauled existing compressors, the unit provides air for the 5,000-litre main foundry receiver.