WEST LAFAYETTE, Ind. - Refineries could trim millions of dollars in energy costs annually by using a new method developed at Purdue University to rearrange the distillation sequence needed to separate crude petroleum into products.
The researchers have demonstrated their method on petroleum plants that separate crude, showing that 70 of the new sequences they identified could enable oil refineries to improve the energy efficiency of this step anywhere from 6 percent to 48 percent, said Rakesh Agrawal, the Winthrop E. Stone Distinguished Professor of Chemical Engineering.
"This is important because improving efficiency by 10 percent at a refinery processing 250,000 barrels per day would save in excess of $12 million a year if oil were priced at $70 a barrel," said Agrawal, who is working with doctoral student Vishesh Shah. "And that's just a single refinery. For the U.S. petroleum industry as a whole, this is a huge potential savings."
Research findings appeared online this month in the AIChE Journal, the official peer-reviewed journal of the American Institute of Chemical Engineers, and will be included in a future issue of the magazine.
Chemical plants spend from 50 percent to 70 percent of their energy in "separations," which are usually distillation steps required to separate a raw material into various products. In the case of petroleum, four distillation columns are needed to separate raw crude into five separate components - naphtha, kerosene, diesel fuel, gas oil and heavy residue. Some of these components are later used to make gasoline.
"Separations are a huge part of what chemical plants do," Agrawal said. "Improving efficiency by only a few percentage points translates into major savings. For every 100 barrels of oil distilled, nearly two barrels go into supplying energy for distillation. That's a lot of oil."
Crude petroleum is fed into the system, heated and vaporized. Vapor rises up the
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