Flexible packaging supplier Gelpack Industrial is saving over 45 per cent on energy used to generate compressed air by using a retro-fit variable speed drive package from EnergAir
A compressed air audit conducted at Gelpack revealed that 40.18 per cent of the input energy used to power its compressors was not productive — and that the system pressure was being kept above what was required. This was due to the inefficient operation of two fixed-speed, 75kW compressors, which were used on a rotating system to provide compressed air to the factory.
But the audit also highlighted the potential savings that could be made by retro-fitting a variable speed drive (VSD) package to reduce offload running and match air generation more closely to system demand.
In the current climate it is essential that all businesses reduce any energy use that is not essential. And one area that can use a lot of non-productive energy is compressed air generation. Many companies are still unwittingly operating systems very inefficiently through excessive compressors idling and unnecessarily over-pressurising systems, says EnergAir. Careful management of a compressed air system can therefore lead to large savings on energy as well as reducing a company’s overall carbon footprint.
Demand for compressed air on most sites will fluctuate. Fixed-speed compressors will produce the same amount of compressed air regardless and regulate between a loaded (low pressure set point) and unloaded (high pressure set point) state. Consequently a large amount of energy is wasted on unloaded running.
However, a variable speed drive connected to a control pressure feedback loop is able to measure the demand precisely, regulate compressed air generation and replace low and high pressure set points with a single ‘target pressure’ set point, thereby keeping the system at optimal pressure without generating excess air.
Retro-fitting VSD package
“We were aware that compressed air systems often run inefficiently so decided to examine the possible savings that could be made," said Gelpack's Paul Burns." EnergAir was able to show how a variable speed drive, sensor feedback and a basic communication box could almost halve the cost of running the system. Recommending a retro-fit VSD package rather than a whole new compressor also made the costs far more manageable.”
In order to improve the sites efficiency it was recommended that Gelpack retro-fit a VSD to one of the existing compressors. Gelpack opted to install an EnergAir Solutions retrofit variable speed drive and control package that ensured the system synchronised perfectly between the two compressors.
EnergAir’s drives and controls package is able to maintain the mechanical integrity of the compressor and actually enhance electrical protection, thereby ensuring the upgrade would not adversely affect the compressor. Installing the VSD resulted in a substantially lower peak current draw and less non-productive energy usage.
Using the VSD to generate compressed air that matches demand has meant that Gelpack has seen massive savings since installation. The system now runs with over 92 per cent efficiency, at all times keeping within 0.21 bar of the optimal system pressure. This increased efficiency has reduced annual energy costs by over 45 per cent, saving over £15,000 pa, with the equipment paying for itself within a few months.
