Energy savings in compressed air

Compressed air can be one of the most important utilities for industry; however, it can also be one of the largest consumers of energy. Therefore, any savings made in the production of compressed air can make a significant impact on costs and the environment.

Australian mining company, Orica, has set itself several operational sustainability goals, including reducing its energy consumption by more than 15% per tonne of production by 2010. The Orica IES site in Heldion, Queensland, had this goal in mind when its air compressor was due for replacement.

The site produces initiating systems used in mining applications for ignition of detonation and is composed of the two production processes, assembly and extrusion. Compressed air is vital to both processes, with it being used to drive pneumatic machines and controlling robots respectively.

Site maintenance manager, Trevor Luck contacted Atlas Copco to help find an optimal energy-efficient solution.

In order to identify any energy savings opportunity, it is important to firstly determine the existing system's air demand profile. Traditionally, compressed air installations were sized by a rule-of-thumb measurement of a given system's theoretical compressed air demand; however, this imprecise process had led to oversized systems which, combined with fixed control systems (load or no load), use much more energy than necessary.

Atlas Copco commissioned an air measurement survey at Orica. By analysing a week's air demand profile using Atlas Copco's air measurement box system, the maximum and minimum air demand and the degree to which this demand is varied could be quantified.

With this information at hand, the GA55 variable speed drive (VSD) compressor was recommended for the site. It has the ability to save up to 35% in energy consumption compared to traditional load/no-load compressors. This is due to the system's ability to follow the air demand profile, thereby eliminating inefficient running.

The air compressor upgrade at the Orica site is expected to deliver over $6000 worth of energy savings in the first year alone. Luck's advice to others is to commission an air measurement survey when examining options, otherwise companies could be 'scratching in the dark' for the optimal solution and may not realise the actual energy savings potential of VSD compressors.