Atlas Copco was called on to carry out an iiTrak system energy audit to check the load cycle profile for each compressor in KPL’s system. The goal of this exercise is to create a representation of the air and energy being used during a typical production week. This data monitoring exercise is then used to extrapolate an annual use of compressed air, the energy used and its cost.
The results of assessment revealed that the existing fixed-speed compressor rated at 110 kW and producing 333 l/s, was operating within a fluctuating pressure band of 1.60 bar. This meant the compressor was loading and unloading between 6.4 bar and 8 bar. Every time a compressor unloads it wastes energy while the motor is idling but the air inlet control is closed and the unit is not producing air*. A general rule is that for every 1 bar a compressor operates above the required pressure the system will potentially use 7 per cent more energy.
The recommendation was to install a 90 kW Atlas Copco GA90 VSD rotary screw compressor with air quality ancillaries. As the lead unit, this would match the variable production air demand in the region of 39-293 l/s and cope easily with the existing and anticipated demand. In practice, the company’s existing fixed-speed compressor was retained as back up and together with its dryer, receiver, oil water separator and pipework was re-sited from its warehouse location to the main compressor room to accompany the new GA VSD unit.
Dale Gunn commented: “Atlas Copco was brilliant from the start, monitoring our existing equipment and recommending a new system that could operate on a lower pressure band yet provide adequate volume for any future expansion of our production output. The energy savings we’ve gained from the new installation have been even greater than originally predicted and are now estimated to be in the region of £47,000 per year.”