Compressed Air Systems: How to Improve Efficiency

Compressed air is a critical resource in production plants – for materials conveying, machine operation and dust extraction – but it’s not free.

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The energy used to provide that air is often a major overhead. For some, those power bills are a thermometer telling them of the likelihood of thriving, surviving or perishing. With better sensors and control systems, it’s possible to reduce bills and the need for maintenance and improve production all at the same time.

Simple Control Systems

Above all, the efficiency of pneumatic systems is determined by the sophistication of the controls. Clearly, it makes sense to match the supply of air with demand. This can just mean having switches to turn it off or on. Most of our homes have devices that detect when they’re not needed and switch themselves off: it’s astonishing how many factories don’t. Pressure switches are often all that will be needed to control the compressor.

With constant speed control, the motor runs continuously but the compressor is unloaded when its discharge pressure exceeds demand. A better method is a variable speed drive (VSD) that controls the motor speed, delivering a steadier supply with minimum energy consumption.

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Complex Production Demands

In more complex pneumatic plants, the air supply and the air required at different points in the line may be varying independently, changing according to both the location and phase of the process. Adding pressure-affecting devices like blast gate dampers, accumulators, filters and switches at key locations can help, but their usefulness is haphazard without reliable sensors to detect when and where adjustments are needed.

Identifying the best locations to fit them requires modelling too, informed by intelligent sensors. Centralised control systems that model, test and implement sophisticated process control are available from leading developers.

Reliability

The other factor determining the efficiency of a compressed air system is its reliability. Adding sensors and control devices is pointless if faults still play havoc with production schedules. (For the best electrical control components in Ireland, see http://www.osmelectrical.com).

For example, oil-free compressors may run for 20 years, but their performance degrades, and poor air filtering, running temperatures or moisture content can affect equipment down the line. Variable speed compressors might cut 50% from energy consumption, but only effective sensors will allow you to know when this makes sense and how much you are saving.

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