Despite its widespread application, however, up
to two-thirds of the compressed air systems in operation have
either an obvious problem that affects production or a hidden
problem that drives compressed air production costs higher. In some
cases, according to the U.S. Department of Energy, compressed air
generation may account for as much as 30% of the total electricity
consumed by the facility. Compressed air is one of the most
expensive uses of power in an industrial facility. Opportunities
for increasing the overall efficiency of compressed air systems
occur on both the supply side and the demand side of the
systems.
On the supply side, typical opportunities include installation of
a variable speed drive (VSD) compressor, a more efficient dryer
matched to the quality and quantity of compressed air demand, the
addition of compressed air storage, and modifications to or
implementation of more effective compressor and system controls.
The optimization goal for the supply side is to operate the
compressors at their highest efficiency point. This goal may be
achieved by operating the minimum number of compressors at full
load and at the lowest possible pressure range, and using a
VFD-controlled compressor for trimming.
On the demand side, opportunities include reducing compressed air
usage through selecting appropriate equipment and practices,
implementing effective leak repair programs, managing pressure
swings without additional compressor capacity, and lowering system
pressure when appropriate. Optimizing a compressed air system has
the potential to generate energy efficiency improvements in the
range of 20% to 50%. By incorporating "Best Practices" design
methods into the front-end development of new construction or major
retrofit projects, end users of compressed air can achieve
dramatically lower electricity consumption, along with improved
reliability and stability of the compressed air system, monetary
savings from reduced electricity consumption and reduced wear and
tear on the equipment, and reduced emissions of greenhouse gases
associated with electricity generation.
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