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Newsletter 2003 issue 3 |
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Energy in the Air
At many facilities,
producing compressed air uses 30 percent of the plant’s
total electricity. Over the life of a compressor,
energy costs will be five to 10 times the compressor’s
purchase cost. To produce one horsepower (hp) of air force,
an air compressor needs seven to eight horsepower of electricity.
Considering electric costs, ensuring that air compressors
run as efficiently as possible is a good idea.
Leaks
All compressed air systems have leaks. Keep leaks to a minimum
by correcting them as soon as they are found. Annually test
your system during periods of non-production to determine
its overall leak rate. Generally, leak rates below five percent
of total compressed air use are considered acceptable. Compressed-air
system leaks can be costly—an 1/8 inch diameter hole
in a 100 pounds-per-square-inch gauged system can cost you
$1,240 per year in wasted energy.
Heat recovery
Eighty percent of the energy going into an air compressor
is converted to heat. You can use this heat to supplement
space or water heating requirements. For air-cooled compressors,
use duct work to divert the hot discharge air into heated
areas. Include a bypass to outside for when the heat is not
needed. This can save you about 50,000 Btus per hour per 100
cubic feet per minute of compressor capacity.
Inappropriate use
Look for inappropriate uses of compressed air at your facility.
Instead of using compressed air, use air conditioning or fans
to cool electrical cabinets; use blowers to agitate, cool,
mix and inflate packaging; and use low-pressure air for blow
guns and air lances. Disconnect the compressed air source
from any unused equipment.
For more information about maximizing the
energy efficiency of your air compressors visit MnTAP's
energy Web page and the following Web sites.
Compressed
Air Challenge—Compressed Air System Economics
Kaeser
Compressors—Achieve Significant Savings Through Improved
Energy Management
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