Energy Efficiency Case StudiesFLYING J PETROLEUM REFINERYSalt Lake CityIn August 1998, the Flying J Petroleum Refinery replaced its hot lime softener, which removes hardness and alkalinity from boiler feeder water, with a reverse osmosis unit. Project benefits include lower energy costs from reduced boiler blowdown requirements, lower maintenance costs from eliminated lime slurry handling requirements, and reduced waste disposal costs because no lime is discarded. The project was implemented at a total cost of approximately $350,000. Annual net savings have reached approximately $200,000, resulting in a 1.75 year payback period.
The hot lime softener was used to remove these minerals and maintain efficient boiler operation. Flying J had been looking to replace the hot lime softening process since the late 1980s, to both reduce costs and increase system reliability. In late 1995, they decided on reverse osmosis technology, and worked with Culligan International to design and build the unit. The city water used in the refining process is now filtered at the molecular level before entering the refinery boilers.
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Flying J processes 25,000 barrels per day of crude oil. Minerals that occur
naturally in the Salt Lake City municipal water supply, such as calcium,
magnesium, and silica, tend to precipitate out in the refinery’s steam boilers,
resulting in tube fouling that significantly reduces boiler efficiency and run
length.
The reverse osmosis unit began operating in August 1998, with an
implementation cost of approximately $350,000. The most significant benefit of
the replacement project has been the reduction in boiler blowdown, a process
whereby water is discharged from the boiler to a sewer to avoid the negative
impacts of dissolved solids on boiler efficiency and maintenance. Blowdown
wastes energy since the discharged water is at about the same temperature as the
steam produced by the boiler. Boiler fuel consumption costs have been reduced by
nearly $165,000 per year. Additional savings result from reduced needs for
boiler treatment chemicals, maintenance, and waste disposal. These push total
net savings to approximately $200,000 per year, resulting in a payback period of
1.75 years. The reverse osmosis unit has proven to be more reliable and require
less operator attention than the hot lime softener.