Page 336 - Corrosion Engineering Principles and Practice

306 C h a p t e r 8 C o r r o s i o n b y W a t e r 307

Device Applications Monitoring Results
Boiler tube leak Fossil boilers Early detection and
monitor location of a tube leak
Acoustic emission Feedwater heaters and Early detection of tube
leak detector other heat exchangers leaks
Cavitation monitor Feedwater piping and Early detection of
pumps cavitation noises
Stress and All types of steam cycles Actual on-line stresses,
condition and major components temperatures, and
monitoring system other conditions; used
to determine damaging
conditions and residual
life
Turbine blade LP turbines Resonant frequencies
telemetry and alternating stresses

TABLE 8.12 (continued)

items listed in Table 8.10 can be found in a special Electric Power
Research Institute (EPRI) report [16].

8.6 Water Treatment
Through the natural water cycle, the earth has recycled and reused
water for millions of years. Water recycling, though, generally refers
to projects that use technology to speed up these natural processes.
Water recycling is often characterized as unplanned or planned. A
common example of unplanned water recycling occurs when cities
draw their water supplies from rivers, such as the Colorado River
and the Mississippi River, that receive wastewater discharges
upstream from those cities. Water from these rivers has been reused,
treated, and piped into the water supply a number of times before the
last downstream user withdraws the water. For example, it is
estimated that the water flowing in the Mississippi River has been
used approximately seven times by the time it reaches the Gulf of
Mexico. Planned projects are those that are developed with the goal
of beneficially reusing a recycled water supply.
In many areas, the availability of new intake water is limited.
Thus, in those industries requiring large amounts of cooling water, it
is necessary to conserve available supplies by recirculating water.
Industries producing primary metals, petrochemicals and paper
typically require large volumes of water in the manufacturing
processes. Recycled water can satisfy most water demands, as long as
it is adequately treated to ensure water quality appropriate for the
use. In uses where there is a greater chance of human exposure to the