Transcript
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
