The two projects are expected to cost more than $250 million -- making the construction project the company's largest since 1995 in Corpus Christi. The construction project is expected to take 18 months to complete.

"We are committed to efficiently providing quality products to our customers," said Joe Coco, executive vice president of operations for Flint Hills Resources. "With the addition of these two new units, we will enhance our ability to produce ultra low-sulfur diesel for a growing Texas market. In addition, we will gain flexibility when it comes to efficiently processing heavier and sour crudes."

The sulfur recovery unit will allow the refinery to handle additional feedstocks that improve the refinery's competitive position.

The diesel desulfurization unit offers the company opportunities to upgrade low-value products into high-value products such as ultra low-sulfur diesel.

"We have been a part of the Corpus Christi community since 1981 and we've continued to enhance our ability to serve customers in that time," said Phil Gaarder, vice president and manufacturing manager for the Texas refinery. "We were the first to introduce low-sulfur gasoline in Central Texas in 2001. When this capital project is completed, we will have spent about $3 billion on acquisitions and capital expansions, many of which have resulted in significant improvements in our ability to produce cleaner-burning fuels and reduce emissions."

Flint Hills Resources' Corpus Christi refining complex is among the nation's lowest-emitting refineries. Latest data indicate air emissions of commonly regulated substances of 0.09 pounds per barrel of crude oil refining capacity. The industry average is 0.19 pounds per barrel of refining capacity.

The construction project will likely begin this fall and will require help from contractors employing about 500 employees at peak periods.

Flint Hills Resources, LP employs about 900 in Corpus Christi. It produces transportation fuels and aromatic chemicals at its 300,000-barrels-per-day facility. A leading refining and petrochemical company based in Wichita, Kan., Flint Hills Resources has completed capital expansions and acquisitions worth more than $3 billion since 2002. The company employs about 3,700.