Michelle Knott takes a look at how advances in compressor technology continue to drastically improve energy efficiency – and the innovations just keep on coming.
There’s really only one big issue when it comes to compressed air and that’s energy efficiency. That’s first and foremost because we’re all slaves to the laws of thermodynamics, which means that any waste of compressed air or extra inefficiencies in generating it will add up to much bigger hole in your energy budget than other utilities. For example, the Carbon Trust calculates that a leak of just 3mm in diameter could cost more than £700 per year in wasted energy.
Energy efficiency is also at the top of every sensible compressed air user’s agenda because optimised energy use and environmental performance are increasingly important for maintaining a good reputation, in addition to the maintaining healthy profits. And with some of the choicest ‘low hanging fruits’ now pretty much a done deal (making the switch to LED lighting is a great example), compressed air systems now present a ripe opportunity for process operators looking to ‘green up’ by reducing their energy consumption.
There’s no doubt compressed air should be high on the agenda of any enterprise seeking to reduce its carbon footprint
Stef Lievens, business line manager for Industrial Air, Atlas Copco
“With conservative analyses estimating it accounts for 10% of all energy used in global industry, there’s no doubt compressed air should be high on the agenda of any enterprise seeking to reduce its carbon footprint. Thankfully, there have been significant advances in recent years that can enable companies to drastically improve both production and energy efficiency,” says Stef Lievens, business line manager for Industrial Air at Atlas Copco Compressors UK.
For many operators with an installed base of compressed air equipment, the obvious starting point is a compressed air audit. “Assessing a compressed air system is non-intrusive and the time it takes to identify savings is relatively short,” says Lievens. “For instance, the recommendation is to undertake a data-logging exercise which, apart from approximately 15 minutes for set-up, has no impact on production. Most importantly, it results in a detailed energy report that, among other things, can flag up how much energy could be being lost through leaks in compressed air pipework.”
Compressors are also among the machinery that will typically benefit from the incorporation of variable speed drive technology, which varies the operating speed to match the demand coming from the process.
What’s more, Atlas Copco claims that its latest generation of VSD+ air compressors can take energy efficiency even further, according to Lievens: “Through the integration of intelligent inverters and interior permanent magnet motors within VSD+ compressors, it’s possible for compressed air users to realise even greater energy savings of up to 50% compared to conventional fixed-speed machines, and 15% over standard VSD machines. This is without mentioning the significant floor space savings they provide against stationary compressors of comparable power ratings, which is a result of their compact design and a unique vertical build concept.”
For example, in a recent installation, David Smith St Ives achieved 40% savings in energy costs by replacing ageing stand-alone units with a centralised rotary screw VSD vacuum pump system from Atlas Copco’s distributor, Anglian Compressors. The manufacturer of engineered timber products depends heavily on an uninterrupted supply of plant air and vacuum across its site near Cambridge, so production continuity and reliability was another a key factor in the decision to make the switch.
Lievens also believes that the arrival of the Internet of Things (IoT) or Industry 4.0 is having a positive impact on compressed air performance, just as it is in many aspects of process operations.
He says that working smarter and more flexibly can offer several advantages: “What is also worth considering are the benefits of IoT-enabled remote monitoring systems, such as SmartLink, which can be used to intelligently predict future compressed air usage patterns and make recommendations on how to further improve system optimisation. Furthermore, with about 90% of the electricity you put into a compressor capable of being re-used elsewhere through the application of energy recovery systems, why not be smart and convert it into heating for your water supply or warehouse?”
These are all areas worth exploring for any compressed air consumer and can often yield major benefits. However, none of them involve fundamental changes to the underlying compressor designs that lie at the heart of all these systems. That’s something that relative newcomer Lontra is hoping to change.
Lontra first hit the headlines in 2012 when inventor, founder and CEO Steve Lindsey [pictured below] announced that he’d come up with a new compressor design, which is essentially a curled up, doughnutshaped version of a piston and cylinder arrangement (there’s an animation on the company’s website that illustrates how it operates).
This enables the machine to rotate continuously but it remains a far cry from conventional rotating compressors in terms of performance, claims Lindsey. “The design has a constantly open and large intake port. It also forms an excellent seal, which significantly reduces internal leakage and therefore waste and energy loss.”
The company initially started by testing out the invention in the water industry, with Severn Trent taking the lead by swapping out some of its existing low-pressure compressors – commonly known as blowers. These pump air at around 1 barg (2 bara) through wastewater as part of the treatment process.
“Severn Trent did their own independent testing and showed that compared with a brand new machine over seven months of running it was 21.2% efficient. They were originally looking for a few per cent but that was a step change,” says Lindsey. “It was so big that they said it would save them more that £1.8 million in electricity per year, just for running their blowers [across all their sites]. Our latest machines will be more efficient still, so we’ll happily be in that 20 to 30% more efficient range… Within Europe, 10% of industrial electricity goes to running compressors. If we can save 20 or 30% of that, that’s 2 or 3% of European industrial electricity.”
Building on ideas
Rather than manufacturing the compressors itself, Lontra initially licensed the technology to Sulzer for use in the water industry. However, the company is currently in the process of building its own production facility in Warwickshire, working in partnership with Shield Engineering Group. This site will begin by making a range of low-pressure compressors aimed at other industry sectors – most notably as blowers in pneumatic conveying applications.
So we’ve got a machine that’s well-proven in the water industry, so where else do they use these low-pressure machines? Pneumatic conveying is behind a surprising range of industries, including baking, pharmaceuticals and cement manufacture
Steve Lindsey, CEO, Lontra
Lindsey explains the reasoning behind the new focus on conveying: “So we’ve got a machine that’s well-proven in the water industry, so where else do they use these low-pressure machines? Pneumatic conveying is behind a surprising range of industries, including baking, pharmaceuticals and cement manufacture.”
However, he’s keen to stress that there is no design limitation that prevents the Lontra technology reaching into the higher pressure ranges: “In the same way that you can get tiny, low-pressure piston and cylinder machines, you can get higher-pressure ones or you can get vacuum pumps, you can apply our technology across the same range. So our new facility will launch a range of new low-pressure compressors first, followed by a range of vacuum pumps (a lot of our benefits of low leakage and good thermal control and efficiency are very appealing to the vacuum market). Following that, we already have a 10 bar compressor on our test bed, but we’re not going to launch that until we’ve launched the low-pressure and vacuum ranges, really for reasons of bandwidth. This will take us into the medium-pressure market.”