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 use of lights and/or audible signals, alert an operator that some variable is
outside the normal operating range. Most systems automatically initiate a
shutdown procedure under certain conditions to prevent equipment damage. With
increasing use of remote,unattended compressor installations, the demand for
the highest degree of protection and reliability has brought about many
advancements and lessened the need for operator involvement. Many control
systems provide a completely automatic sequence for starting, operating, and
shutdown of compressors.
The more advanced control systems are able to
optimize equipment efficiency by controlling one or more variables to obtain a
specified level of performance.
5 COOLING WATER TREATMENT. Cooling water systems are used in compressed air
plants to remove heat from engines, air compressors, refrigeration condensers,
intercoolers, and aftercoolers.
These cooling systems are classified as
either once-through or recirculating. Once-through systems often require
nothing more than chlorination to prevent biological fouling of heat
exchangers. Treatment is more critical in open recirculating systems because
of solids buildup due to evaporation. As hardness and other solids increase,
probability of mineral scale formation in heat exchangers increases. To
combat scale damage, chemical additives are used to keep scale-forming salts
in solution. Dissolved oxygen and carbon dioxide are prime corrosion
developers. Corrosion control is provided by addition of inhibitors. Slime
accumulation and fouling may be prevented by the addition of chlorine or other
biocides. Solids concentration is controlled by blowdown. More detailed
information on cooling water treatment is contained in the proposed
publication, NAVFAC MO-225, Industrial Water Treatment.
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