Compressed air – the most expensive source of energy in production
The generation of compressed air is cost-intensive and has a comparatively low efficiency due to high conversion losses (waste heat generated by compression). Nevertheless, the use of compressed air in industrial applications has remained, or is still a growing market – even if the use of compressed air today is more than ever in competition with electrical or hydraulic systems.
The main advantages of using compressed air driven systems are:
- Working speed (very high, due to high flow rates)
- Reliability (simple construction, low wear)
- Maintenance (very low wear, no media change)
- Handling (pneumatic devices are usually significantly lighter than electrical ones)
- Operational safety (even at very high temperatures)
- Accident safety (especially against fire, explosion, electrical hazards)
- Clean and dry (even with leaks)
- no return (air escapes into the environment)
- good storage of compressed air
- stepless controllability with simple means (chokes)
Nevertheless, a cost-benefit analysis should generally be used when using compressed air, as the supply costs of compressed air are often very high and other systems can therefore achieve a higher overall efficiency. This applies in particular to the “misuse” of compressed air in applications in which the “pressure” is not required, but the “flow velocity” of the air.
The most common and usually very costly applications of compressed air are for other purposes:
- Use of compressed air for cleaning purposes (blowing off chips, lubricants, etc.)
- Use of compressed air as cooler replacement (cooling of machine parts, production processes, etc.)
- Use of compressed air for drying purposes (e.g. profiles, pipes after the cooling tanks)
- Use of compressed air to provide local cooling functions (e.g. for curved profiles)
How can the costs for compressed air supply be reduced?
There are different starting points for the optimization of compressed air systems. Studies have shown that in practice more than 50% of the compressed air energy generated is already destroyed in the compressed air network (by losses). But other approaches are also helpful and can significantly reduce the costs of providing compressed air:
- Use of energy-efficient systems for compressed air generation
- Use of waste heat recovery options for the compressors
- Degree of filtration (as low as possible but as much as necessary)
- Compressed air drying (as low as possible but as much as necessary)
- Reduction of line losses through sufficient dimensioning
- Use and dimensioning of compressed air reservoirs (centralised / decentralised)
- Elimination of pressure-consuming throttles (couplings, valves, etc.)
- Prevention / elimination of leaks / automation of leak detection
- Ensuring a high flow pressure to avoid slow tool running times (flow pressure is not equal to static pressure!)
- Short cable lengths to the load
- Use of ring pipelines in the system
- Compressor control and regulation strategy
- Complete avoidance of misuse such as cleaning, cooling, drying
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