Compressed air is a key utility for manufacturing but it doesn’t come cheap. That’s why it’s important to ensure it maintains efficiency, cautions Greg Pitcher.
If you need convincing of the benefits of improving the efficiency of your compressed air kit, there is a simple way to get motivated.
“We’ve all heard hissing as we walk around a factory,” says Michael Pingram, product specialist for oil-free air compressors at Hertfordshire-headquartered equipment manufacturer Atlas Copco UK.
“In your head, change that noise to the sound of coins rolling down the drain. You’ll quickly realise how much money could be saved by simply finding and fixing leaks in the compressed air distribution pipework.”
Such action – while highly advisable – is just the beginning of a deeper process to optimise the way a plant uses pressurised gas.
“Compressed air is widely used in all manufacturing,” says Pingram. “Almost every product produced, from biscuits to cars, uses compressed air at some point in its production.”
He says that, despite being so critical a part of the process, the utility is expensive and can push up the price of end products.
“By the time compressed air is produced, treated, regulated and distributed it has made a significant contribution to the operating costs of a plant. With an inefficient compressed air system, costs are increased for everyone.”
According to Pingram [pictured], some 10% of the electricity produced in the UK ends up powering compressed air systems.
“If customers use modern compressors and treatment, the combination of various small efficiency gains means we could see up to 50% reductions in electricity use.”
A tailored approach
The first stage in optimising the system is understanding the exact requirements of the particular process it is being used for, Pingram says.
“A lot of users only see the point-of-use compressed air and don’t give much thought to how it gets there,” he laments.
“Manufacturers’ outputs change and their compressed air system remains unchanged – wasting money or, worse, causing lost production issues.”
Pingram says using unnecessarily refined air is a waste of money that could push product prices up above those of competitors for no good reason. Similarly, not building in enough treatment risks, allowing contaminants through to affect a product or process and ultimately reduce quality.
Accessories such as filters and dryers have an essential role to play in optimising the quality of compressed air by removing common contaminants such as dust, oil and other liquids.
For hyper-sensitive applications – for example in the food and pharmaceutical sectors – an oil-free compressor can be the best option. However, these can come at a high price due to the coating required to remove the need for lubrication. So over-specification can itself be wasteful.
Pingram recommends an air audit be carried out to ensure a thorough understanding of the requirements of a system.
Smart controllers can be used to regulate a system, ensuring a factory doesn’t produce more air than it needs.
“The Internet of Things seems to be the flavour of the day, and it’s easy to see why,” says Pingram. “Real-time monitoring of all aspects of production can mean problems are spotted way before they start costing money to rectify or cause lost production incidents.”
Manufacturers’ outputs change and their compressed air system remains unchanged – wasting money or, worse, causing lost production issues
Michael Pingram, product specialist, Atlas Copco UK
Atlas Copco has several options available to monitor the compressed air generation process. Its SmartLink service, built into new compressors and dryers, allows a user to monitor their system from anywhere in the world.
Data is a key tool for process plant chiefs to maximise the efficiency of pressurised air, according to the latest president of the British Compressed Air Society, former corporate banker Jason Morgan.
“We are all aware that electricity accounts for a significant proportion of compressed air cost of ownership and therefore finding new ways to minimise energy consumption is key,” he says.
“Typically, this has been achieved by investing in new, energyefficient machinery but now, with the availability of so much data, operators can realise far greater control over their existing compressor estate, monitoring performance parameters 24/7 if required to ensure the most efficient operation.”
Morgan says up to nine in 10 manufacturing plants use compressed air, with applications ranging from air tools on production lines to adjusting roller and feed machinery, as well as packing with pneumatic devices.
“Compressed air is accepted widely as a highly effective and safe form of power for the process industry. However, generating the high-volumes of air demanded by the application can be energy-intensive.”
Mother of invention
Demand for reduced energy costs has driven creation of improved technologies in the pressurised gas field, says Morgan.
“We are seeing a real shift in thinking, with end users now considering the total cost of equipment ownership over its entire life, rather than just its initial capital price. This is important because over 80% of this cost base can be in the system’s energy consumption and maintenance in the 10 years after the initial purchase.”
He says variable-speed drive technology is used widely across the process industry to enable a compressed air system to adjust air production according to factory demand.
“Of course, the benefit of installing an efficient compressor package is only realised if it is installed as part of a system that is equally energy efficient. It is a mistake to focus on only one aspect of the system to the exclusion of others.”
Maintenance is also a vital part of overall cost and efficiency. “End users are realising that moving towards regular routine maintenance rather than reactive maintenance is far more cost effective and will help to reduce unplanned downtime,” says Morgan.
This brings us back to his point about the usefulness of data. “With the continued emphasis on Industry 4.0, many operators are benefiting from far greater insight into their compressor performance and preventing potential system faults before they occur.”
Of course, as Pingram demonstrated with the analogy about coins rolling down a drain, preventing leaks is the most obvious but also most critical step to compressed air efficiency.
“If a site purchases the most efficient compressor on the market but then connects it to a system that has a 40% leak rate, all they are achieving is to produce waste more efficiently,” says Morgan.
With the availability of so much data, operators can realise far greater control over their existing compressor estate… to ensure the most efficient operation
Jason Morgan, president, British Compressed Air Society
The BCAS has produced a white paper called Reducing Energy Consumption From Compressed Air Usage. It also runs a one-day training course to help operators understand any obligations under the Pressure System Safety Regulations, which generally apply to those in charge of systems using greater than 0.5 bar and containing an air receiver.
Dirk Slottke, sales and marketing director at JP Sauer & Sohn Maschinenbau, says a common mistake made by process manufacturers is underestimating the difference between low-pressure and high-pressure gas and air applications.
“We help our customers solve the various challenges that a high-pressure system poses,” he says. “This includes special high-pressure equipment for treatment, distribution and storage of high-pressure air and gas.”
Work is taking place in many quarters to improve the efficiency of compressed air in manufacturing.
At the University of Portsmouth, the School of Mechanical and Design Engineering is overseeing a research project into the use of artificial intelligence to cut energy consumption from the systems.
“This project aims to create intelligent and interactive systems that are more responsive to industrial needs and workers’ actions and become true accessories for optimising the energy efficiency of manufacturing systems,” says reader in systems and knowledge engineering at the university, David Sanders.
“The concept is to combine ambient sensing, artificial intelligence and knowledge management to optimise energy efficiency for energy-intensive compressed air manufacturing units.”
