COMPRESSED AIR
CUTTING COMPRESSED AIR COSTS WITH VARIABLE-SPEED TECHNOLOGY
According to the UK Government’s Department for Business, Energy & Industrial Strategy, in 2019, industrial and commercial compressed air systems in the UK consumed around 10 TWh of electricity per year, which is equivalent to approximately six per cent of the UK’s total industrial electricity consumption.
his figure will come as no surprise to operators in the manufacturing and process industries, who are all too familiar with the significant amount of energy compressed air systems can consume. And, as energy prices continue to rise at an unprecedented rate, businesses are seeking innovative ways to cut their electricity consumption from compressed air, without compromising on performance. Stephen Taylor, Territory Leader UK, Ireland, Nordics, A&GS Europe at Ingersoll Rand explores the benefits of variable-speed compressors and how they can help lower electricity consumption.
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FIXED VS VARIABLE SPEED Conventional compressed air systems have tended to prioritise the use of fixed speed motors, which mean they run at a consistent speed and produce a fixed volume of air, regardless of the plant’s demands on the system. In most scenarios, the exact amount of compressed air generated is unlikely to be required, leading to potential wastage of both the air, and the energy used to generate it. In addition, fixed speed compressors run unloaded, as the stress of an engine start-up would put pressure on the motor. This can consume electricity unnecessarily as the machine is running without producing any compressed air. Variable speed compressors, on the other hand,
use an intelligent drive system to constantly alter the speed of the motor and match the air generated to the required process demand. This allows for the required high speeds for compression while generating sufficient flow to meet plant requirements, thus minimising power consumption. A variable speed compressor can achieve energy savings of up to 30 percent when compared to a fixed speed compressor and can help reduce power surges, avoiding peak currents from starting the compressor’s motor. The benefits of variable speed compressors go beyond energy savings. Precise electrical controls ensure motors can be easily slowed down, stopped, or revved up, and the risk of leaks is minimised through the lower system pressure that is achieved.
Minimising leaks in a compressed air network is another key benefit, and one of the most important energy saving measures for businesses. According to the Carbon Trust, a 3mm hole could cost over £1,000 a year in wasted energy.
VARIABLE-SPEED IN ACTION The Metal Drum Company, a manufacturer of steel drums, is one such organisation to have benefitted from installing variable-speed compressors, saving £23,000 per annum. Thanks to a programme of energy-efficiency improvements, The Metal Drum Company
is benefitting from a new, CompAir L160 RS, variable-speed drive machine at its main Chilton site, delivering payback in just 3.5 years; alongside a smaller L75 machine, offering 3.7 years’ payback at its Hull facility - from CompAir distributor, Air Compressors and Blowers North (ACB)
SPECIFYING THE SYSTEM During the wrapping and painting process, The Metal Drum Company has a high demand for air, which was proving costly. With the rising price of energy, alongside the environmental demands being placed on manufacturers, the company approached ACB to see if a programme of compressed air system improvements could be made to help reduce electricity consumption. The original 110 kW, fixed-speed machine had already been replaced for a CompAir L160 oil- lubricated compressor, to help increase capacity, and had been providing reliable performance for over 20 years, with minimal maintenance issues. But, with its belt drive and fixed-speed operation, the compressor could only run at a constant speed, consuming 160 kW of electricity, regardless of the demand for air generation. The same scenario applied at the Hull facility, where a CompAir L75 fixed-speed compressor had been running reliably for 10 years, but with no speed-regulation available on the drive. Engineers from ACB carried out energy data logging on both sites, which showed that each compressor was running continuously, when actual demand was between 50-60 per cent. A speed-regulated, direct drive compressor solution was proposed, which would ensure that each machine was optimised to meet the peaks and troughs in air demand.
26 APRIL 2023 | FACTORY&HANDLINGSOLUTIONS
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