Steam Traps Solve Sticky Railcar Heating Problem

Steam Traps Solve Sticky Railcar
Heating Problem
The U.S. uses an average
of nearly 29 million tons of
asphalt annually. Typically,
asphalt is transported from
process plants to points of
use by railroad cars, truck,
and barges.
A large multi-mode terminal operation that
serves all of these transportation modes
wanted to duplicate the railcar heating
improvements experienced by two of
its nearby asphalt suppliers. The Spirax
Sarco team described the railcar heating
successes at two nearby asphalt plants.
Heating Asphalt in Railcars
Many liquid products in railcars—especially
asphalt—have a high viscosity at ambient
temperature and must be heated in order
to pump it from the railcar to the storage
tanks. Asphalt is not heated during transit
because the railcars don’t have a steam
source. Instead, the shipping terminal
usually has its own boiler or purchases
steam from a nearby plant or cogeneration
unit. The temperature of the asphalt
directly affects its unloading time and
consequently heating costs. Asphalt at
ambient temperature can take as long as
24 hours to heat before it can be unloaded.
In addition to asphalt, tank-type railcars
transport many different kinds of
chemicals. However, each railcar that’s
capable of hauling asphalt has an internal
steam coil. A steam inlet and a condensate
outlet on the side of the railcar provide the
steam to the coil. When a railcar arrives
at the terminal, an operator connects
the steam supply to the coil’s inlet and
connects the condensate outlet to the
condensate return line, which typically is
permanently equipped with a steam trap.
Optimum temperature depends on the
product. In most cases, this is a manual
process where the operator heats up
the railcar using a fixed steam pressure
based on his experience. Products with
higher viscosity require more heating time
to achieve a higher temperature. Typical
steam pressure is less than 100 psig.
Steam traps play a critical role in the
asphalt heating process. They drain
the condensate from the coils while
maintaining the steam pressure in the
system. They also vent air during startup.
Air interferes with the heat transfer
process, causing the asphalt to take
longer to heat up. Typically, high-capacity
thermodynamic steam traps and even
thermostatic traps are used because of
their low cost. However, float traps are
much better for this application because of
their superior performance.
History of Success Repeats Itself
The previous Spirax Sarco successes at
the two asphalt providers helped make
the sale at the transportation company.
In 2002, one of the asphalt companies
approached Spirax Sarco to help with an
asphalt heating problem. It was taking too
long for their railcars to heat using their
existing steam traps. Operators had to
open bleed valves to heat the cars.
Spirax Sarco performed the heat transfer
calculations to estimate the amount of
condensate that would be produced
in this type of application. The team
recommended a float and thermostatic
trap because of its capacity, modulation
capabilities, and its internal air vent, which
is a critical feature in applications where air fills the heating
in other terminals in the area. The unknown trap was one that
space between batches. This application required a 1-inch
the first asphalt plant had purchased in 2002.
NPT FT450-14 steam trap with 1-inch M10H2RB ball valves
for isolation and 1-inch CT strainers for trap protection. The
The Spirax Sarco team recommended the 1-inch NPT FT450-
asphalt provider purchased eight sets of traps, valves, and
10 steam trap because of its superior air handling capabilities
strainers.
and large capacity to handle the initial condensate load. In
December, 2010, the transportation terminal purchased 11 of
After realizing the success the first asphalt plant had with the
the 1-inch NPT FT450-10 traps and CT strainers. In March 2011,
Spirax Sarco steam traps, another asphalt company requested
the terminal purchased another 11 of the 1-inch NPT FT450-10
the same study in 2004. The steam pressure at the second
traps and CT strainers for its holding tanks.
asphalt plant was slightly lower than the pressure at the first
plant, which required a different size mechanism. The second
Optimistic Outcome
asphalt company purchased eight sets of 1-inch NPT FT450-
The transportation terminal gained quick results from installing
10 traps, along with the appropriate valves and strainers.
the Spirax Sarco steam traps. Faster railcar heating eliminated
the need to manually open bleed valves to drain condensate
Superior Steam Solutions
from the tanks. Not only did this make the asphalt heating
In November 2010, the transportation terminal approached
process quicker and automatic, it also increased the plant’s
Spirax Sarco to request traps for the railcar loading rack in a
safety because operators no longer have to manipulate the
new facility being built in the ship channel where the company
steam valves.
operates. During the initial meeting, the team focused on
the successes at the two asphalt plants because their
The transportation company was pleased that Spirax Sarco
requirements were similar.
took the time to discuss the features of the steam traps and to
share past successes. The company said it would be contacting
The transportation company expressed interest in the same
Spirax Sarco in the near future to talk about more traps—and
type of trap used at the other two companies. Since they
perhaps even control valves.
had very little technical knowledge about steam traps, the
team explained why they are needed, the differences in
technologies, and why the more expensive Spirax Sarco steam
trap works better than the competition’s less expensive traps.
The company also asked Spirax Sarco to identify one of its
traps from a photograph because they knew it had worked well
For further information please contact:
Spirax Sarco, Inc
1150 Northpoint Blvd, Blythewood, SC 29016
1-800-883-4411 • spiraxsarco.com/us
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