Contaminant-free compressed air & challenges of lower life cycle cost in operations

21 Dec 2020

On a recent visit to one of the production sites of a major global drinks manufacturer, I was taken aback to learn of the complexity and seriousness of their approach to ensuring oil-free air. While they had employed the latest technologies and machines, they had not foreseen that small oil leaks would be spilled onto and absorbed into the concrete floor during maintenance. This oil would evaporate during the hot season. And that those contaminants would then be drawn into the compressor, leading to minimal, yet important oil contaminants in the final product. Their solution involved placing the compressor equipment in a contaminant-free environment, regular cleaning of an epoxy-resin floor, and strict protocols to maintain this environment.

For food and beverage (F&B) companies, the importance of oil-free compressed air is, of course, nothing new. Oil-free compressors meeting ISO standard 8573-1 specifying purity classes for particles, water, and oil have proven critical. But as with all such stringent standards, they add to costs, energy consumption and ultimately make life harder for operations leaders who need to reduce the Life Cycle Cost (LCC) of their capital investments.

And there is more! As a consumer I’m also acutely aware and proudly part of the consumers’ challenge to all sectors, including food and beverage, to improve the environmental sustainability of their organisations.

From Farm to Fork

A well-known phrase, ‘from farm to fork’, is often used in consideration of the sustainability of the entire food production supply chain. Within this reference, there is rightly focus on the need to avoid contaminants ‘from farm to fork’. Given that compressed air is used across most stages of food and drink production, from oxygenating the water in aquaculture or fish farms, preparing fizzy drinks or in the sanitation of bottles and packaging to name a few, contaminant-free air is a must. And it is a must in a very important industry.

Contaminant-free air ? Low Life Cycle Cost?

Food and Beverages operations require compressed air that is completely oil-free. These applications demand wide operating temperatures of 0-45°C, stringent air purity standards higher than ISO 8573-Class I, high levels of safety, and eco-friendly operation to name but a few. And as in many other industries, the demand is for efficient compressors capable of running with minimal maintenance and for longer periods.

The inadvertent and unintentional presence of contaminants can enter the food chain at all stages: in packaging materials and transport materials for raw ingredients, the improper use of machine oils or lubricants, and in the upstream packaging, process, and transport materials. The ALARA principle states that the presence of a contaminant should be reduced to “As Low As Reasonably Achievable”, clearly establishing the priority for all aspects of food production – especially the compressed air industry.

Filter it out

In an oil-free screw compressor, an air cooler removes the heat from the compression chamber. The dry-running rotors rotate at high speeds to get volumetric efficiencies injected. Timing gears synchronize rotation to ensure no contact. A separate lubrication system lubricates the timing gears. And finally, an effective sealing system prevents the entry of lubricating oil into the compression chamber.

Filtering removes much of the oil but not all of it. For example; pre-filters, high-efficiency coalescing filters, and activated carbon filters remove trapped oil to a great extent. But these filters themselves have characteristic limitations. For instance, above 20°C, coalescing filters do not remove fine oil vapours, leaving very fine particles of residual oil in the form of aerosols, and activated carbon filters are not usable at filtration temperatures above 40ºC because the carbon then absorbs the oil vapour, gets saturated, and becomes ineffective.

Furthermore, to ensure no residual oil, airborne particulates or vapour could enter the system, downstream air dryers and double line filters are used to further purify the air but filtration itself raises two more problems. Firstly, given that approximately 10 million litres of oil have been expelled into the atmosphere over the past ten years from oil-lubricated compressors, the safe and sustainable disposal and re-use of oil continue to be a challenge. Secondly, filters create a drag on efficiency by their very function, resulting in increased energy use and running counter to the very goals of operations leaders in the F&B sector. For every filter that is installed in the downstream compressor line, you increase the differential pressure. This increases energy consumption of approx. 1 per cent per filter. Furthermore, filters are often installed and paired in various combinations in the compressor room and at the point of use, resulting in additional cost and efficiency loss.

Thus, meeting these requirements for contaminant-free air in the F&B sector has always seemed at odds with the need to reduce the Total Life Cycle Cost.

Best of both worlds

Today, innovation and new product development have resulted in solutions that deliver ISO: 8573 (P-2):2007 ‘Class 0’ oil-free air to ensure that 100 per cent contaminant-free air is produced for various applications in their manufacturing and packaging processes.

Until recently, these compressors were expensive and used primarily by large companies and those that exported their products to markets with stringent standards. Now, technology advancement and market developments in oil-free technology and ‘Class 0’ certified compressors have changed the game and every manufacturing company can access technology that assures not only oil-free air that meets the most stringent standards, but also much higher energy savings and uptime at lower Life Cycle Costs.

For example, there are very few compressor companies that design their own oil-free air-ends and even less that make them along with their own pressure vessels, castings, motors while also conducting complete machining and compressor assembly. With in-house technology and manufacturing capabilities of all these various elements, compressors can now be engineered to deliver maximum uptime and reliability, leading to an optimized compressed air system for operators.

Designing compressed air for the operational situation = lower Life Cycle Cost + Contaminant-free compressed air

The technology exists to affordably cater to the dual demands of contaminant-free air and improved Life Cycle Cost. But we can and should do more. As my example at the beginning of this article highlights, Food and Beverage operational leaders need not only have the best and most reliable compressors, but also expert support in designing and optimizing the complete compressed air system – a trusted partner that will understand and tailor their needs to further improve their twin goals.

Plant leaders should consider a ‘bird’s eye view' of the compressed air system – understanding the supply and demand sides, and starting in the point of generation, through transmission and finishing, where the air is used at the end of the line. A solution-focused, comprehensive approach building on the components but holistically looking beyond just the compressor room is essential to lowering the Life Cycle Cost.

Cheers to our F&B sector

The F&B sector must contend with increasingly demanding regulatory challenges regarding quality, safety, and energy efficiency while addressing the need to feed a growing population sustainably. Given that compressed air is often referred to as the ‘fourth utility’ in acknowledgment of its vital role in manufacturing, the compressed air industry must continually innovate to support food and beverage operations in meeting these challenges.

With the advancement in energy-efficient oil-free compressed air, this technology is all set to grow in relevance not just for the Food and Beverage industry but for all applications. Oil-free air will become more prevalent supported by design initiatives to further improve cost and efficiency, data will serve as a key enabler and with this, the evolution of change will speed up delivering ever-increasing savings and improvements for this vital energy source in manufacturing.