Compressor market eyes innovative future

Devices that generate compressed air are so ubiquitous these days that as a commodity, it is almost on a par with electricity, gas and water.

Indeed, most air compression industry insiders proudly declare that compressed air supply is “the fourth utility”.

But compressed air is hugely expensive in terms of energy consumption. Therefore, industry has become focused on ways of cutting the cost of running these heavy duty machines.

System managers are constantly craving for compressor design innovations, whether to reduce noise levels, eradicate costly leaks or improve air flow conditioning.

Improving design

In 2009, Dutch engineering design research company Van Holsteijn and Kemna (VHK) was commissioned by the European Commission to investigate flaws and weaknesses in contemporary compressor designs.

VHK’s first study – ENER Lot 31 – concluded in 2014 that standard air compressor packages are eligible for strict eco-design measures as their future environmental impact will be significant and savings could be achieved without, they concluded, “excessive negative impacts and costs”.

In October 2014 the report based on VHK’s study was handed to a European Commission consultation forum. It decided the report needed more detail, so VHK was called on to start a second study focused on a wide spectrum of compressor types.

The second study is expected to run until 2017, with a report due in 2018/19. For the manufacturers and end users it is a case of “watch this space”.

But on the front line, the real work in improving design, increasing efficiency and building useful energy saving techniques lies in the innovative skills of the engineers and designers in the different sectors.

Most companies are focused on higher efficiency motors and motor speed controllers in their systems. As for energy recovery at 100%, while it may be possible in carefully controlled specific situations, I don’t think it’s feasible in practical terms. In reality 85-90% is about as good as it will get.

Andy Jones, president British Compressed Air Society/MD Mattei Compressors

Manufacturers are taking a whole system approach to efficiency by continually attempting to improve performance of components that make up a system.

Compressors are designed to run for years with parts being replaced piecemeal as they fail, but a 20-year-old compressor is not going to be as energy efficient.

Inevitably, over time the cost of purchasing spare parts will be at greater expense than the cost of replacing the entire unit.

Andy Jones, president of the British Compressed Air Society and managing director of Mattei Compressors, says the sector has its eyes on ENER Lot 31.

“Most companies are focused on higher efficiency motors and motor speed controllers in their systems. As for energy recovery at 100%, while it may be possible in carefully controlled specific situations, I don’t think it’s feasible in practical terms. In reality 85-90% is about as good as it will get.

“At Mattei, we invest heavily in R&D on compressors for efficiency. Our Maxima Xtreme is one of the most energy efficient fixed speed compressors with a specific energy efficiency of just 5.2 W/m3/min. We believe this is about 1.5 W/m3/min better than a good average screw compressor.”

There’s an entire technical paper on the secret of how this was achieved, but in short, the fluid dynamics of the system were optimised within the compression unit, and a new sprayed oil injection system was combined with a high-performance lubricant to reduce internal friction and deliver the improvements. It is a case of small developments yielding big results and that is the mark of the industry.

Flow conditioning detective work

Flow conditioning is a serious issue in terms of efficiency. It’s the key to identifying costly leaks.

“It helps develop a clearer picture of a site’s compressed air usage and when it’s combined with power consumption data, offers excellent data from which decisions on replacement equipment can be made,” says Jones.

Many companies take compressed air management seriously, but there’s still a long way to go.

Fortunately, industry standard ISO11011 has at least provided a framework for the assessment and auditing of energy efficient air systems.

Flow meters for compressed air are great for precise measurement of the compressed air outputs, so companies can pinpoint usage spikes, leakage rates and determine when service or upgrades are required.

Conducting compressed air audits significantly increases profitability and efficiency when completed with the proper compressed air flow meter.

With so much focus on the energy performance of compressors, development work needs a whole system approach. Components are being continually adapted to improve performance

Colin Mander, regional director of Gardner Denver

Colin Mander, regional director of Gardner Denver, says: “We are constantly trying to introduce more energy efficient compressors and we have launched a number of new models this year in our CompAir range of machines.”

Good data logging can also be used to determine the precise system sizing and air volumes required. This can often mean that smaller, more efficient compressors can be specified in place of larger, more energy-intensive machines.

“This has been a trend we’ve seen recently, with the increased demand for variable speed compressors, particularly smaller machines sizes, which are becoming more prevalent as we are able to replace an existing, less efficient machine with a smaller unit,” says Mander.

Education is key

In the US flow conditioning tops the efficiency agenda and the education of end users is the aim of manufacturers and suppliers.

Jim Bowser, sales engineer at Cross Company System Control in North Carolina, encourages awareness among system engineers and facility personnel of the need to use thermal mass flow measurement in compressed air systems.

Because these people are frontline they have an excellent feel for the setup, the duct work and branches of the compressed air system and they can help plan the most suitable flow conditioning monitoring system, he says.

“The usual approach for many of them is to place metering after the compressor air dryers and use that as their base production number – call it the main compressor manifold meter. Then, they add various other meters throughout the duct network and subtract those readings from the main compressor manifold meter.

“Ideally, the net result should be very near to zero which would indicate a complete accounting of air produced and air consumed.

“If the numbers don’t agree, then you can start the detective work and find out which branch is misbehaving and take corrective action.”

More investment on research into flow conditioning and improving the myriad components is also essential.

“With so much focus on the energy performance of compressors, development work needs a whole system approach. Components are being continually adapted to improve performance,” Mander says.

So with the European Commission watching — the message to the stewards of the fourth utility is “keep innovating to keep one step ahead”.