How Refineries Can Save Between 6% and 48% Energy Cost

Oil refineries can save between 6% and 48% of their energy costs of refining, suggests new research from Purdue. The researchers studied the sequence of distillation processes, and discovered 70 sequences (out of a total of 6,000) that were more energy efficient than the current sequences used by industry. This represents a significant cost savings, and a potential competitive advantage for refiners who can adapt these findings to the industrial scale.

"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 first column, and the product is collected in a condenser at the top. The process is repeated in additional columns, with the number of columns depending on how many components are to be separated.

But the distillation is more energy efficient depending on the order in which the columns are operated.

"There are many ways to arrange the columns," Agrawal said.

Shah created a computer algorithm that identifies all of the possible sequences and then determines which require the least heat and energy. The Purdue researchers used their new technique to determine there are nearly 6,000 possible sequences for the four columns used in petroleum distillation.

"Once we know all of the possible ways they can be arranged, then we can tell you which ones have the potential to be the most energy efficient," Agrawal said.

Petroleum refineries have been using the same sequence for about 75 years, and it is the most energy efficient of the sequences known to industry, the Purdue researchers confirmed using their new method.

The researchers also determined, however, that 70 of the new sequences identified have potential to consume less energy than the sequence now used by industry. Those 70 sequences range from being 6 percent to 48 percent more energy efficient than the method currently in use. _SD