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Another Xytel Success Story
Like other U.S. petroleum refiners, the Phillips Petroleum Co. is under federal mandate to significantly reduce the sulfur content in the gasoline it sells in the United States. Federal Environmental Protection Agency regulations call for reductions to be phased in over a six-year period.
In August 1999, Phillips announced the creation of a new technology for lowering sulfur content in gasoline. Early tests indicated that the technology could produce gasoline that easily met the new stringent EPA regulations for sulfur. Shortly thereafter, Phillips announced that they planned to build a demonstration plant at their Borger, Texas, refinery. Construction of the 6,000 barrel per day plant began in the first quarter of 2000 and was scheduled to start up in early 2001.
Phillips first contacted Xytel concerning the design and construction of a continuous operation Low Sulfur Pilot Plant in November 1999. It was critical to have the pilot plant running by early 2001 to support the start-up of the demonstration unit. In February 2000, Phillips awarded Xytel a contract for the design and fabrication of the pilot plant. The project plan included a 7-month fast track schedule from the start of design to delivery of the turnkey system to Phillips.
High temperatures and pressures, and the circulation of catalyst solids made this a challenging project from a process design perspective. Xytel used custom fabricated electric heating mantles to evenly heat the vessels and a proprietary valve design for the accurate and repeatable transfer of catalyst between vessels.
"It was a difficult project, because we had to circulate small amounts of solids. Accurate solid circulation is somewhat difficult as it is. The complexity increased as the amount of solids to be moved decreased to the level needed to meet Phillips’ requirements," says William Freivald, Senior Process Engineer. "In simple terms, a series of consecutive funnels are used to transport the catalyst from the top of the plant to the bottom, where it is pneumatically conveyed back to the top. Each funnel serves a different purpose, from catalyst regeneration by fluidization with air, to de-sulfurization of gasoline by fluidizing it with vaporized gasoline."
The control cabinets are located in the process area inside purged enclosures to save space in the control room. The Honeywell Plantscape control system was programmed for highly automated operation to minimize the number of operators required to run the plant. This includes automated plant start-up and shutdown.
The pilot plant was constructed in a series of six vertically stacked modules with an overall height of 48 feet. Each module contains one or more key process vessels, associated instrumentation, tubing, junction boxes, and necessary vent and utility headers. To fabricate the pilot plant, the modules were stacked in pairs at Xytel’s Elk Grove Village, IL location and shipped in three sections to Oklahoma for on site assembly. The modules were tested at Xytel and then shipped on double-drop trailers to Bartlesville in August 2000.
"Phillips completed installation of the pilot plant in half the time allocated due to the ease of reassembling the modules. The six modules were stacked up and connected for the first time without any problems," said John Lawlor, Xytel’s Project Manager. With Xytel assisting, Phillips completed the pilot plant commissioning and began continuous operation in January 2001.
"We were pleased with the speed and efficiency with which Xytel designed and constructed the unit and with the quality of their electrical work." says Ron Brown, Phillips Senior Research Engineer. "Their know-how allowed us to begin pilot plant runs ahead of our original schedule. This enabled us to begin obtaining data that could be applied to larger-scale testing before we fully commercialized the process."
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