Sean Fairest, the Business Line Manager for Compressor Technique Service at Atlas Copco Compressors, provides four helpful suggestions for improving and maintaining the efficiency of compressed air systems.
1 - Use air audits to provide a clearer picture
To ensure that energy is not being wasted it is advisable to carry out a compressed air audit. This will give a highly accurate, independent survey report and provide a true picture of how much compressed air is being used on site, as well as showing how much energy is being wasted in producing it. The survey will pinpoint any areas where an energy drain may be coming from so that appropriate action can be taken to achieve peak efficiency. Additionally, analysis of usage patterns and a detailed report show precisely where the system could be improved for greater efficiency, flexibility and reduced costs.
2 - Match air supply to air demand
The installation of variable-speed drive (VSD) compressors is recommended to improve compressor performance. In 80 per cent of installations, air demand fluctuates. In 70 per cent of installations, the load cycle lies between 40 and 80 per cent, meaning that there is big potential for energy savings if VSD compressors are used. This is because VSD compressors use an integrated frequency inverter that varies the speed of the compressor motor to match its output to the air demand. This can provide energy savings averaging 35 per cent, as the supply meets the demand rather than staying at the same constant output level. In contrast, traditional regulators do not possess the accuracy to track demand pattern variations, so substantial amounts of energy are wasted.
3 - Keep compressors in top condition at all times
Regular compressor maintenance not only keeps the production facility operating at top efficiency, but it is also an opportunity to reduce running costs. A major portion (around 80 per cent) of the lifecycle cost of a compressor is for electricity, whereas servicing is around 10 per cent.
Regular servicing reduces the energy running costs of a compressor significantly, so the potential gains are enormous. The regular replacement of ancillary products, such as filters that can become clogged leading to pressure drops, will also reduce compressor installation running costs. A clogged filter or inefficient dryer will create a pressure drop and reduce energy efficiency. On average, for every one bar pressure drop incurred, an extra 7 per cent of electrical power will be required to meet production needs.
4 - Use compressor-generated heat to save energy costs elsewhere
Most of the electrical power used by a screw compressor is transformed into heat, but up to 94 per cent of compressor-generated heat can be recovered rather than wasted. A well-planned investment in energy recovery can provide a payback on the original capital outlay within one to three years. The available heat from a water-cooled, oil-injected compressor can be recovered as hot water that can be used on site to reduce energy costs. Connecting it to a heating boiler's return circuit helps to reduce heating costs of washroom supply, radiators and process operations. In the case of air-cooled compressors, the hot air can be ducted for direct space heating.
For more information about compressed air system efficiency, contact the UK-based Compressor Technique Service teams or follow the link to the Atlas Copco website that explains compressor energy savings - www.useyourenergytwice.com.