Lower energy costs, increased reliability and greater efficiency – it’s well worthwhile to take a closer look when planning a compressed air system. The following points provide a brief overview of the most important criteria.
10 steps towards an efficient compressed air system
1. Determine the actual demand pressure for the compressed air system
The demand pressure is determined by the pressures required by the consuming equipment plus the differential resulting from the connection to the air network, pipework, compressed air treatment systems and the switching differential of the compressors. The demand pressure should therefore be calculated by working backwards from the consuming equipment to the compressors. The pressure differential between the consuming equipment and the maximum compressor pressure should ideally be no greater than 1 bar. In certain cases (for example, if especially high compressed air quality is required) it can be slightly higher. However, if the differential turns out to be significantly higher, take another look at the system plan.
2. The right pipework is essential
Installation of the wrong pipework can also negatively impact compressed air quality. The pipe material should therefore be appropriately suited to the production conditions (e.g. corrosion resistant, impervious to chemical influences, etc.). The pipework should be correctly dimensioned and be installed in such a way as to keep pressure losses to an absolute minimum. Websites from compressed air system providers often have useful tools available that can help users calculate the optimum pipe diameter. The piping connections should always be completely airtight in order to prevent costly leakages. Threaded or hemp-sealed pipe joints are unsuitable for compressed air systems. For best results, pipes should be welded or joined by press fittings; in an emergency, they can also be glued. Following installation, leakage tests should be carried out at regular intervals.
3. Air receivers – Proper planning, selection and positioning
Air receivers are key elements in any effective compressed air system. The receiver should be chosen according to the type of compressed air demand (continuous or intermittent) and should be sized to suit the needs of the application. An air receiver should also be installed at points in the compressed air network that are subject to frequent intermittent compressed air demand.
4. Configure compressed air treatment components to meet actual requirement
The minimum requirement for compressed air treatment is refrigeration drying, since it prevents corrosion, damage to consuming equipment, as well as impaired product quality caused by water. All higher levels of treatment such as filtration or desiccant drying are production-dependent. Note: it is imperative to include a compressed air stop valve when designing the air system! This valve prevents the air treatment components from being overwhelmed when the compressors are started and consequently stops water from entering the air distribution network.
5. Select and combine compressors wisely
A compressed air audit should be carried out prior to investment of resources in a compressed air system. When planning a new system, perform a simulation based on maximum and minimum consumption values. This step will help determine correct dimensioning of the compressors and will indicate whether they should be speed-controlled or not. The application itself will determine the type of compressor (dry-running of fluid-cooled) that will be used. Never select compressors that are too large, as they can be inefficient during partial load operation and are difficult to control. Graduate compressor sizes in such a way that no control gap occurs.
6. Master control means more than just enhanced efficiency
Master controllers nowadays should not only be capable of activating and deactivating compressors according to demand in order to minimise control-related losses, but should also provide comprehensive monitoring and preventive maintenance features. The ability to display air consumption and energy demand is also essential to ensure that utilisation is compliant with energy management regulations as per EN/ISO 50001.
7. The right space makes for quality compressed air production
Because compressors generate heat, it is important to keep optimum ventilation in mind when it comes to compressor room layout. Plan sufficient space for maintenance and use a thermostatic control for colder times of the year to ensure that the machines maintain correct operating temperature at all times.
8. Heat recovery saves energy costs
Compressors convert 100 percent of the energy they use into heat. It is therefore absolutely essential to consider the options for heat recovery that are available for heating purposes or for process water, for example. This aspect can lead to significant energy cost savings in other operational areas.
9. Think environmental protection
The condensate resulting from compressed air production contains contaminants from the intake air and must therefore be effectively removed via monitored condensate drains and always be subsequently treated in order to safeguard the environment.
11. Funding programs can help with financing
Much of the capital outlay for compressors, associated equipment and services can often be offset by government funding programs – sometimes by as much as 30 %. A quick look at the applicable country-specific guidelines will confirm whether the costs to the company itself can be considerably reduced.