POWER December 2010 - 22

6. Brush and basket. Cleaning of the condenser occurs when the flow is reversed by a series
of butterfly valves installed in the crossover piping. At this plant, baskets (with purple brushes
inside) are being added to each condenser tube. The force of the water pushes the brushes
through the tubes to keep the inside wall of the tubes clean. Courtesy: Ovivo USA, LLC
8. Remote monitoring. Henry AungKyi,
Linde's reliability engineering manager for
Greater China, inspects PdM and operating
data at Linde's Remote Operations Centre in
Shanghai. Courtesy: SKF
ness. PM activities are usually timebased:
Machine adjustments are made
and replacements parts are ordered on
a routine basis without regard for the
operational performance or condition
of the major piece of equipment or its
component parts.
In contrast, predictive maintenance
7. Recirculating balls. Elastomer balls
injected upstream of the condenser will remove
micro fouling from condenser tubes.
The external ball collector is used to replace
the balls once a month as they wear down.
Courtesy: Ovivo USA, LLC
7). This system consists of uniquely designed,
slightly oversized elastomer balls
that are periodically or continuously injected
upstream into the heat exchanger
or condenser cooling water inlet.
The balls are passed through the tubes
by the water flow. A strainer/ball collector
is installed at the water piping exiting the
condenser. A nonclogging pump removes the
balls from the strainer and reinjects them
back into the water supply line after they
have passed through external collectors.
-Contributed by Kaveh Someah (kaveh
.someah@ovivowater.com), Ovivo USA,
LLC, formerly Eimco Water Technologies
cally reverse the flow through the heat exchanger
and shuttle the brushes through
the tubes. The flow returns to its normal
direction within a few minutes. In the
case of the power plant condenser application,
the flow reversal is performed
at night and only through one-half of the
condenser. The plant must reduce load for
this type of condenser cleaning. For small
heat exchangers such as auxiliary coolers,
a single in-line flow diverter valve is used
to accomplish the periodic backwashing
without requiring any reduction in plant
load.
Balls. The other, more common, system
used to remove micro fouling and scaling
from the heat exchanger and condenser
tubes employs recirculating balls (Figure
22
Expanding the Use of
Predictive Maintenance
as a Business Strategy
The Linde Group is a world-leading gases
and engineering company operating in
more than 100 countries. It's no surprise
that the company uses a variety of advanced
monitoring techniques and equipment
to keep its plants operating reliably.
In the U.S. and UK particularly, Linde
plants have used online machine condition
monitoring for a number of years.
At its Shanghai headquarters, Linde has
formed a large and impressive remote
operations center where it monitors and
tracks the process operations of all its
major gas plants in China 24 hours a day
(Figure 8).
Many process and manufacturing
plants use preventive maintenance (PM)
programs, but PM has limited effectivewww.powermag.com
(PdM)
is a condition-based approach
that builds a picture of the anticipated
condition of a component or piece of
equipment based on trends of important
operating data taken while the equipment
is in service.
The data collected by Linde mostly
consists of vibration analysis data, but
it also includes lubricant analysis, temperature
measurements, and the like.
Based on this trend data, and applying
principles of statistical process control,
an engineer can predict the best time to
conduct equipment maintenance. This
approach allows the technician to costeffectively
plan maintenance work. Because
most PdM data collection occurs
when the equipment is in service, there
is minimal disruption to production.
Integrating PdM
When Linde acquired the BOC gases
company in 2006, it embarked on a program
of integrating its new China-based
assets into Linde's PdM-based operation
and maintenance (O&M) organization.
Linde O&M activities are process-driven,
meaning that they are focused on
process optimization and continuous
improvement. After the acquisition, the
company's first step was to assess the
maintenance processes at each of the
newly acquired plants and develop an
improvement plan. Linde's long-term
goal is to bring all maintenance activities
at all its plants to the same level
of PdM expertise and share information
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POWER December 2010

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