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Air compression: Looking to the future

18 July 2018

Is any industrial system or solution truly future-proof? Probably not, but in some fields the horizons are certainly extending. Mark Whitmore, general manager of compressed air specialist, BOGE, explains

In reality, the marketplace in any industry is so fluid that new needs will tend to make existing approaches obsolete eventually. And no matter how advanced today’s technology, you never know when a development team is going to make a quantum leap in an unexpected direction.

However, some machine systems are deliberately designed for continuous upgrading to stretch out their operating life, even in the face of long-term change in business requirements. Good examples can be found in the compressor market, which provides one of the vital ingredients of modern manufacturing: clean, reliable compressed air.

In short, it is now feasible to replace key compressor components as improved technologies emerge. With the use of laser metal additive processes, upgraded parts can even be custom-manufactured for specific applications. At the same time, Industry 4.0 advances in automation and data exchange are optimising the selection and performance of such upgrades. We are also seeing fresh thinking in terms of how end users can upgrade most economically.

Turbo technologies

The latest technological developments and possibilities can be illustrated with reference to the latest high speed and low pressure compressors. These use advanced technology that, even without further upgrades, gives these machines a longer lifespan – so we can expect to see them working further into the future. They also offer operating economies, especially in terms of energy efficiency, which are ahead of their time. The following information on what makes these modern machines so different from those of the past will help to clarify the current and potential contribution of their innovations.

No oil

Historically, one of the great steps forward by manufacturers was the introduction of oil-free compressors, which in theory neither consumed oil nor contaminated the operating environment. Traditional oil-free machines require oil for some of their drive components. Although these components are separated from the airside of the compressor, cross-contamination could occur in certain extreme circumstances. Now, turbo technology has eliminated the need for oil entirely.

Confidence in 100% oil-free compressed air is essential in many sensitive manufacturing sectors, such as food and beverage, pharmaceuticals, coatings and semiconductors. The low-pressure versions also have application in areas where a constant flow of low pressure air – typically 2 to 4 bar – is required.

Low total cost of ownership

Essential to recent progress has been a reduction in the number of components in compressors, and particularly the removal of those which tend to wear. As well as prolonging product life and minimising maintenance demands, this has resulted in substantially smaller, lighter and more convenient machines.

New-generation compressors are much quieter, thanks largely to low-friction engineering, which also cuts down on frictional wear and energy losses. Gains in energy efficiency have been achieved throughout the design, meeting one of the developers’ priority objectives. In many production facilities, air compressors are the biggest individual consumers of energy. Savings on energy and maintenance bills, combined with long product life, result in a low total cost of ownership.

Energy efficiency

High energy density is a key characteristic of the compact permanent magnet (PM) motors which drive turbo compressors. These are in highly efficient, require no gears and can be inverter-controlled to match supply precisely and instantaneously with demand. 

Their central rotor is suspended on a self-stabilising, frictionless air foil bearing. With no friction, negligible energy loss, and high power, rotation rates of 100,000 and above can be generated. Compared with the magnetic bearings more conventionally used in compressors, air bearings are virtually maintenance-free. In addition, they do not require a power back-up device for protection in the event of a mains power failure.

At each end of the rotor is an impeller, made from light and hard-wearing titanium. The two impellers, varying in size and blade arrangement, are application-designed for optimum effectiveness. 

The special design of the impellers, diffuser and spiral casing creates negative pressure on the intake side, so fresh air is sucked through the motor. There is therefore no need for a separate fan cooling motor and control unit, so additional savings are made on wear, maintenance and energy consumption. Pressure is boosted in three stages, or two in low pressure compressors, to reach the necessary levels quickly and efficiently.

Upgrading

Despite these advances, compressor manufacturers accept that there will always be room for future improvement. Sustainability demands and economic pressures continue to drive energy-saving developments, in particular. 

To accommodate changes and upgrades, compressors need to be built with a modular structure in which parts can be easily swapped. At the moment, customers seeking an upgrade can be shown a variety of appropriate alternative components from which to choose. In the near future, they will be given the option of fully customised components, thanks to the growing availability of additive metal manufacturing and other agile production techniques.

But can customers be sure that the cost of upgrades will be justified by the improvement in performance achieved? In one new model for covering the costs, for example, BOGE gives a guarantee that the price of the upgrade will be paid for by the resulting energy savings. In this way the end user shares in the cost but takes no risk.

Help from Industry 4.0

Assessment of whether upgrading or reconfiguring of air compression equipment is necessary can now be aided by Industry 4.0 technology. In this scenario, advanced internet-connected monitoring and diagnostic capabilities, built into each compressor’s control system, routinely log machine performance and energy consumption. 

The information gathered is transmitted securely to the supplier, whose simulation tools evaluate efficiency against the maximum possible. Reports indicate the changes in operation or configuration that could improve those figures. If there has been a substantial change in the user’s demand for compressed air, the tool may recommend upsizing or downsizing of components for more efficient operation. If a new and improved component has been developed, the tool will quantify the effect of upgrading with it.

Along with smart remote monitoring and reporting, Industry 4.0 technologies offer help to users to get the best from their compressors by enabling efficient predictive maintenance, diagnostics and repairs. Artificial intelligence technology can be applied to learn how a compressor operates and performs normally, and to warn of any abnormal behaviour. Engineers can then determine, remotely, whether further investigation or action is needed.

In the Industry 4.0 world, you might not even have to wait for the supplier to come and repair your compressor. Wearing smart glasses, the customer’s engineer can share his or her view of the equipment with the supplier’s engineer, who will give step-by-step guidance on repairing it.

 
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