Industrial plants use compressed air throughout their production operations, which is produced by compressed air units ranging from 5 horsepower (hp) to over 50,000 hp. The US Department of Energy (2003) reports that 70 to 90 percent of compressed air is lost in the form of unusable heat, friction, misuse and noise . For this reason, compressors and compressed air systems are important areas to improve energy efficiency at industrial plants.
It is worth noting that the running cost of a compressed air system is far higher than the cost of a compressor itself . Energy savings from system improvements can range from 20 to 50 percent or more of electricity consumption, resulting in thousands to hundreds of thousands of dollars. A properly managed compressed air system can save energy, reduce maintenance, decrease downtime, increase production throughput, and improve product quality
Compressed air systems consist of a supply side, which includes compressors and air treatment, and a demand side, which includes distribution and storage systems and end -use equipment. A properly managed supply side will result in clean, dry, stable air being delivered at the appropriate pressure in a dependable, cost-effective manner. A properly managed demand side minimizes wasted air and uses compressed air for appropriate applications. Improving and maintaining peak compressed air system performance requires addressing both the supply and demand sides of the system and how the two interact.
Main Components of Compressed Air Systems
Intake Air Filters : Prevent dust from entering a compressor; Dust causes sticking valves, scoured cylinders, excessive wear etc.
Inter-stage Coolers : Reduce the temperature of the air before it enters the next stage to reduce the work of compression and increase efficiency. They are normally water-cooled. After-Coolers: The objective is to remove the moisture in the air by reducing the temperature in a water-cooled heat exchanger.
Air-dryers : The remaining traces of moisture after after-cooler are removed using air dryers, as air for instrument and pneumatic equipment has to be relatively free of any moisture. The moisture is removed by using adsorbents like silica gel /activated carbon, or refrigerant dryers, or heat of compression dryers
Moisture Drain Traps: Moisture drain traps are used for removal of moisture in the compressed air. These traps resemble steam traps. Various types of traps used are manual drain cocks, timer based / automatic drain valves etc.
Receivers : Air receivers are provided as stora ge and smoothening pulsating air output - reducing pressure variations from the compressor