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Recognising your air inefficiencies

15 April 2019

Andrew Power explains how food processing plant owners and operators can ensure their compressor is as efficient as possible to realise financial and operational gains. 

Compressed air is essential to many food production plants, providing a reliable and versatile source of power. However, it does take large amounts of energy to produce the clean, dry, pressurised air that is required to power a plant’s many processes and applications. 

The UK food processing industry uses over 20TWh of electricity to compress air – the equivalent to the output of four power stations and constitutes a major expense. 

Ensuring maximum energy efficiency and minimal wastage should therefore be a top priority for food production businesses of all sizes. As such, recognising inefficiencies and opportunities for optimising performance is increasingly vital for operators looking to save money and improve their plant’s overall productivity. 

Total cost of ownership continues to be a major factor when considering compressor efficiency. It is affected by many factors – for example, energy costs constitute over 80% of a compressor’s total cost of ownership, according to industry averages. With energy costs in mind it is important that any compressed air unit should be specified, suited and sized appropriately according to site demands. Failure to do so can lead to prohibitive ongoing maintenance costs, as well as a higher up-front purchasing price. 

Purchasers can avoid this initial over-specification by installing a performance-monitoring data-logging device. By auditing and recording important metrics, such as minimum and maximum required air pressure and air flow demand, plant owners and operators are better informed to choose a correctly-sized compressor. 

Plant owners and operators should also consider up-front costs when looking to reduce a compressor’s total cost of ownership. Though it can be tempting to purchase a less proven compressor for a lower initial purchase price, ensuing maintenance costs could well lead to an erosion of any early savings.

Energy audits
Because energy costs account for more than 80% of a compressor’s total cost of ownership, undertaking a thorough and detailed energy audit could reduce total cost of ownership, while delivering improved efficiency levels.

Energy audits can be instrumental to improving a site’s operational efficiency, showcasing where energy is being wasted and where it can be recovered,. 

Any audit should include a pre-assessment survey looking at factors such as the current compressor configuration, amount of power, flow and temperature required for a full survey, estimated leak survey time needed, and an awareness of site shift patterns, current electricity costs and instances of compressed air misuse. 

Awareness of these variables can have a huge impact – for example, if inlet temperature rises by 4°C, compressor energy consumption increases by 1%. Similarly, increasing pressure by 1 Bar can lead to a 7% increase in energy consumption.

Leakages and contamination
A full audit will highlight key areas and factors that can hamper a compressor’s overall efficiency, and identify opportunities to improve productivity, safeguard product quality and reduce site downtime.

Accounting for 35% of total air consumption, pipework leakages are a large factor in compressed air energy wastage that can be addressed through an energy audit. There are many reasons for leaks in a compressed air system, including shut-off valves and manual condensate valves being left open, and leaking hoses, couplings, pipes, flanges and pipe joints. Such oversights and deterioration can be costly – according to the Carbon Trust, just one 3mm leak could cost a company over £700 a year in wasted energy.

Compromised piping can also lead to compressed air contamination, as unsealed joints, cracked pipes and open valves letting air out can also let moisture and contaminants in via osmosis. This can result in reduced productivity, downtime and product spoilage, all of which is expensive to resolve. Implementing a more thorough maintenance regime based off audit findings can reduce the likelihood of blocked inlet and downstream filters or contamination, resulting in lower overall running costs. 

Energy audits can also be used to quantify a compressor’s possible heat potential. Approximately 94% of compressor-generated heat can be recovered for use in other processes, meaning it is vital to owners and operators wishing to realise efficiencies.

This heat can be recovered via various methods. This includes installing an energy recovery unit fitted to the oil circulation system, or through space heating – recirculating warm air from the compressor to a local area. This energy can also heat water supplies in manufacturing processes where heated water is required, such as central heating, hot water washing and steam systems. 

Finally, an energy audit can pinpoint areas in the pipework system where upgrades might be required to reduce pressure drops. These drops are created by old, and incorrectly-sized or laid-out pipework systems with too many bends, tees or fittings, and must be compensated for by the compressor expending more energy. This increased inefficiency and rising total cost of ownership could otherwise be avoided with an audit.

Having the ability to share and analyse data throughout manufacturing processes – in line with Industry 4.0 practices – allows compressed air users to consider how they can improve performance and identify inefficiencies. So connectivity and Internet of Things (IoT) initiatives, that can assist with performance optimisation, leak reduction and practical air management processes, are increasingly seen as a necessity.

With this in mind, Gardner Denver has introduced iConn, which delivers detailed compressor performance data via a cloud-based air management platform. By providing predictive and cognitive analytics for historic and real-time performance, operators can stay in control of their installation and rectify potential concerns before they happen.

Because it gives operators a way to monitor real-time data that provides in-depth reports on machine parameters, over-time trend analysis and where and how energy waste occurs, iConn can help reduce overall compressor fault occurrences. 

Optimising performance and recognising areas of inefficiency is a key priority for owners and operators wishing to improve a plant’s financial performance. By taking account of factors such as total cost of ownership, correctly specifying compressors, implementing rigorous energy audits and engaging with the latest data analytics software, it is possible to maximise a plant’s overall energy efficiency.

Andrew Power is country manager at Gardner Denver.

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