In the past, the availability of compressed air has been treated as an unlimited commodity that costs virtually nothing — similar to how we used to view water before climate change — however, most now know this is not the case. In Australia, about 10% of all industrial electricity consumption is powering compressed air with around 15% of that energy typically wasted through leakages.
In the present 'climate change' environment, saving, not wasting, air and improving the energy efficiency of a compressed air system is of the utmost importance and this can result in triple bottom-line savings for industry. For example, saving a 10 L/s compressed air leak can result in an energy saving of about 7 MWh/y which equates to a cost saving of about $1000 (at 15c/kWh).
In order to improve the energy efficiency of a compressed air system, it has to be managed efficiently and must include:
- Regular audits to highlight leaks and pressure losses
- Regular maintenance and repair work
- Correct selection of operating pressure and sizing
- Control of usage
- Control of temperature
- Condensate removal or elimination.
Over the last few years there has been a push for industry to use 'Zero Air Loss' type drains. These drains prevent the unnecessary loss of compressed air while ensuring the compressed air condensate is removed from the system when collected in receivers and other collection points.
Case study
Jorc Industrial (an international manufacturer of auto drains) has developed a full range of different styles of drains, including zero air loss drains. On a recent site visit to one of its customers, who has installed the zero air loss drains throughout the factory, an interesting problem was detected.
Underneath the roof the company has a large air receiver (3 x 1 m) horizontally installed.
The plant manager talked about the daily activities as they stood next to the receiver tank. He mentioned that at the end of the day the receiver is full of compressed air (7 barg), however, when they come into work the next morning, the receiver is empty.
A quick investigation showed that this equated to a compressed air loss of 3 m³/min per day. It would have been more if the compressor had been left on during the night because the compressor would kick in automatically to bring the system pressure back up to 7 bar, fuelling the air losses even further.
The customer had been convinced of the benefits that zero air loss drains offer, but was not aware of the compressed air leakages in the system.
The benefit of installing a zero air loss drain (so that at least there is no air lost at the draining point) is worthless when other air leaks are not detected and you lose more than a complete receiver's worth of compressed air each working shift. In comparison, a timer drain's potential air loss seems minimal compared to this amount of air lost through pipe work, leakages etc.
Jorc has developed a system called the Air-Saver to help with situations like this. If it was installed at this factory, it could save the receiver tank's content of produced compressed air rather than it being wasted unnecessarily. The subsequent search for the pipe work leakages could then be easily carried out with the help of an ultrasonic air leak detector. Jorc has an ultrasonic air leak detector called Locator and it could be used for this task.
A leak detection program is a vital part of effective energy-efficiency management of a compressed air system. Installing zero air loss drains is only part of the solution; management of air leaks with products such as Jorc's Air-Saver and Locator will also assist with this process. Further information on these tools is available from SCS Filtration, www.scsfiltration.com.au.
