The British and American governments estimate that as much as 10% of all electricity generated is consumed by air compressors, and that some 50% of this energy is wasted. Air leaks alone can account for 25% of these values.
Compressed air auditing is no longer a luxury, it is essential. By not knowing the facts around your compressed air consumption, you are doomed to a spiralling electricity bill.
Key points for a compressed air audit
What are the components of a comprehensive air audit? These are the basic steps in reducing operating costs for your compressed air system:
1. Measure the air flow and pressure entering a system for at least seven days.
2. Monitor and determine the compressor’s Kw/m3 efficiency.
3. Monitor and measure the consumption in various areas of the plant and benchmark your usage.
4. Measure the quality of the compressed air, dew point, particle count and oil carry-over, and classify your air quality.
5. Undertake an ultrasonic leak detection survey.
6. Identify wasteful air consumption practices.
7. Quantify the actual cost in these areas.
Air flow testing
On many sites compressors are often not operated at full capacity. By logging the flow and the power from the compressors, engineers will be able to determine a base load for the flow required in a plant. With detailed information, main load compressors can be selected from an existing fleet, with perhaps a variable speed drive compressor topping up the flow requirements. This type of decision will use power more effectively and cut energy wastage and costs
Air velocity
Compressed air velocity can be a useful pointer to the efficiency of a pipeline and/or distribution system.
High velocity = pressure drops = wasted power.
High velocity will carry airline contamination to the point of use.
Discharge pressure on occasion gets increased to overcome a poorly designed or overloaded piping system. This then in turn demands more power and pushes up maintenance costs, resulting in wasted kilowatts.
Leak detection
Ultrasonic air leak detection demands a methodical approach. The survey should identify the leak location points, the volume of compressed air lost, and the cost of the air wastage. This must be presented in a readable easy format.
Dew point
A blocked condensate drain, an open bypass valve, or worse still a fractured heat exchanger are all potential causes of water pollution in a factory. Compressed air dryers can pollute an air line for days before the cause of the pollution is located and rectified.
A dew point probe behind the dryer identifies a water contamination problem faster than any machine minder. These probes can easily be linked to a Scada system. A good air audit will show the flow, pressure, relative humidity and dew point in one concise graph
Auditing capacity
Make sure your auditor has the capacity to monitor all areas simultaneously to ensure a total overview within the same time frame.
Conclusion: auditing is a science
Auditing has now become a science. It requires a substantial monetary investment in equipment to provide a comprehensive overview for a client. This includes monitoring to ISO 8573. Auditors must have the ability, experience and knowledge to analyse and interpret the data to provide a meaningful report to the client.
| Tel: | +27 11 420 0274 |
| Email: | allen@articdriers.co.za |
| www: | www.articdriers.co.za |
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