POWER March 2011 - 20

5. Deep cleaning. Rosebud Operating
Services used the Conco air-cooled
condenser cleaning system to restore lost
performance when manual methods failed.
The cleaning system uses 12 computer-controlled
nozzles to thoroughly clean the entire
surface area of the ACC tube bundles.
Courtesy: Conco Systems Inc.
6. Thorough washing. Seen from
beneath the ACC, high-pressure water from
the spray nozzles removed the fouling from
Rosebud's elliptical air-cooled condenser
tubes. Courtesy: Conco Systems Inc.
temperature days, where the cleaned
ACC can perform efficiently at the higher
temperatures. On the bottom line, we're
saving about $180,000 a year. "
-Contributed by Eric Fayard (eric@
concosystems.net), marketing manager for
Conco Systems Inc.
of the system are adjustable to take
into consideration all types and sizes of
air-cooled condensers, including vertical
and flat coolers and " A-frame " and
" V-frame " configurations. The Conco
system, when it arrived at Rosebud on
its own trailer, included the framework,
computerized traveling nozzle assembly,
pump, hoses, and all ancillary equipment
(Figure 6).
" The system was set up by the two
about an 8-inch circumference. Cleaning
hundreds of thousands of square feet
this way took forever. We would first
clean from the top of the tube bundles
and the dirt would be pushed half-way
through. Then, we would spray from the
bottom, and the dirt would be pushed
back up about half-way. The water, although
under pressure strong enough to
bend the tubes if held too closely, just
could not make it through the tube bundle.
The efficiency factor was extremely
poor. This system also was not easy on
the man operating the lance, and safety
is always an issue. "
Looking for an alternative solution, Gray
did an Internet search and came across information
about the FinTech ACC cleaning
system developed by Conco Systems Inc.
in Verona, Pa. " I went to observe them
cleaning an air-cooled condenser outside
Las Vegas and was extremely impressed,
said Gray. " I contracted them within a
month of that event. "
The Conco system also uses high-volume,
high-pressure water to clean the
tube bundles, but unlike the hard-tocontrol
high-pressure lance, the FinTech
ACC cleaning system features a computer-controlled
12-nozzle water jet assembly
(Figure 5). The frame and tracks
20
Conco technicians who brought it here, "
said Gray, " and we provided what was really
minimal help to get everything set
up. The Conco crew has been a pleasure
to work with. They operated the cleaning
system up to 12 hours a day and had
the entire condenser thoroughly cleaned
for us by the end of the week. "
Because different condenser manufacturers
produce their condensers with
differing designs and cooling requirements,
Conco's FinTech ACC system has
been engineered with the ability to
adapt to those varying configurations
by changing the angle at which the
water hits the tube bundle. Plain water
is used, eliminating any possible environmental
concerns. The nozzles themselves
are designed with varying degrees
of approach to the bundles. This permits
the Conco technicians to select the
nozzles that are the most efficient for
a particular condenser configuration,
resulting in thorough surface cleaning
without any tube damage.
" The plant began realizing performance
increases after the Conco crew
had cleaned just one-quarter of the
condenser. Overall, we see up to a 10%
increase in ACC efficiency, recovering
about 3,000 MWh each year. The primary
improvement is during high-ambientwww.powermag.com
Plant
Safety: Learn from
the Mistakes of Others
On January 27, the U.S. Chemical Safety
Board (CSB) released a case study examining
the causes of a heat exchanger rupture
and ammonia release at the Goodyear Tire
and Rubber Plant in Houston in 2008. Use
these lessons learned to check your employee
tracking system and to determine
whether your plant has installed valves
that violate the American Society of Mechanical
Engineers (ASME) Boiler and
Pressure Vessel Code.
The CSB event summary begins by
noting that the accident occurred on
June 11, 2008, when an overpressure in
a heat exchanger led to a violent rupture
of the exchanger that hurled debris,
which struck and killed a Goodyear
employee walking through the area. The
heat exchanger contained pressurized
anhydrous ammonia, a colorless, toxic
chemical used as a coolant in the production
of synthetic rubber; five workers
were exposed to ammonia released
by the rupture (Figure 7).
On the day prior to the accident,
maintenance work required closing several
valves on the heat exchanger. CSB
investigators found that workers closed
a valve that isolated the exchanger from
a relief valve, to replace a burst rupture
disk located below the relief valve.
The next day, at about 7:30 a.m., an
operator closed another valve-this one
blocking a second, automatic pressure
control valve-to begin cleaning the
process line with steam. The operator
was unaware that the isolation valve
was also closed, thus leaving no means
of relieving excess pressure in the exchanger.
As a result, pressure continued
to increase until the heat exchanger exploded
violently.
Employee Training Lapses
Managers ordered the plant evacuated.
However, CSB investigators found that
on the day of the accident, the employee
tracking system was not operating properly,
making it difficult to quickly account
for all employees.
The CSB found that a malfunction in
the computerized electronic employee
badge-tracking system delayed superviPOWER
| March 2011
http://www.powermag.com
POWER March 2011

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