Compressors need care and caution

Frankfurt, Germany – ?Lack of awareness about the cost of generating compressed air and the amount of energy being wasted by some systems is an EU-wide problem, believes Nicola Piccardo, general industry market manager, European served area at Ingersoll Rand.

Many process companies across Europe are unaware of how inefficiently their air production systems are operating and lack strategies to address the issue, according to Piccardo who is based in Ingersoll Rand’s Milan, Italy office.

For example, he said, in the food and beverage sector, compressors have often been added as plants have grown over the years without any thought of optimisation.

“But replacing two or three smaller compressors with a single large unit can lead to significant efficiency improvements, said Piccardo. “For instance, moving from small screw compressors to a centrifugal compressor four to six times larger can deliver 15-20% greater efficiencies depending on the pressures involved.”

Overall, though, he advises companies seeking to improve compressor efficiency to start with their biggest machines, as “the greater the volume of air, the greater the cost savings possible.”

Meanwhile, Piccardo estimates that just about 30% of companies are aware of the benefits of air system audits. The remaining 70%, he said, see them as a cost and don’t realise the potential savings.

But audits must be carried out correctly and the data properly and carefully analysed as, cautioned Piccardo, conclusions from these can sometimes be misleading.

He cited a recent example of a glass manufacturer in eastern Europe which found it was generating excess air from its six centrifugal compressors between 8am and 10am in the morning.

An audit by another supplier showed that a variable speed compressor could reduce energy consumption over this two-hour period - worth around Euro10,000 a year.

But the two-stage 400kW variable speed screw compressor was 40% less efficient than a three-stage centrifugal compressor, said Piccardo.

The glass manufacturing company, he estimated, would have ended up spending Euro80,000 each year to save just Euro10,000 a year on excess compressed air generation.