Nuclear Plant Journal, July-August 2016 NuclearPlantJournal.com
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but in this case a rapid acquisition process
was employed so that the pump could be
manufactured in a timely fashion.
Improved efficiency and
performance:
Several key value-added propositions
helped to increase efficiency. First, the
wear-ring geometry was optimized for
reduced leakage losses and for greater
pump reliability. Second, with the use of
advanced technologies, the high casting
quality of the hydraulic parts improved
the dimensional accuracy and the surface
finish. Third, the impeller and the stage-
casing hydraulic passages underwent
additional surface polishing to further
improve the surface finish without
compromising dimensional accuracy.
The efficiency improvement with
this custom pump design is especially
critical for this power plant because the
set up with diesel generators results in a
fixed amount of power available. Hydro’s
3% efficiency improvement at the 6,000
GPM @148 FT design point results in
a lesser BHP which not only provides
energy savings but also represents an
added margin of safety especially with
respect to diesel power. [Fig. B]
Given that all pumps wear over time
(resulting in a small loss in efficiency),
this 3% reduction in power required
represents a buffer with respect to when a
pump might need to be pulled for repair,
refurbishment, or replacement. Another
area of improved performance resulted in
a lesser measured maximum axial down
thrust. The custom pump provides a 35%
margin from the allowable down thrust.
Thus the motor bearing temperature in
the plant will be reduced.
Conclusion: Reliability,
greater efficiency, and
peace of mind
Stringent QA throughout the design
and manufacturing process and the
development of a testable prototype meant
that the customer could be confident in
standardizing on the new design without
extensive field testing. While the design
and manufacture of a custom pump
does require an intensive effort, many
benefits accrue in choosing this path. In
the long run this solution results in an
upgrade that pays for itself over time.
The plant can rest assured that the backup
pump will perform as needed, a chronic
cycle of repair has been mitigated, and
regulatory specifications will be met with
ease. Finally, one of the most significant
benefits is that the plant will realize the
benefits of improved efficiency year after
year.
Contact: Hydro Inc., 834W. Madison
Street, Chicago, IL 60607, telephone:
Fig. B: Hydro custom-designed pump performance vs. pre-existing OEM pump
