DuPont (Wilmington, Del.; edlinks.chemengonline.com/6900-531) has acquired hydrotreating technology for desulfurizing motor fuels and hydrocracking intermediate refinery streams from Process Dynamics, Inc. (Fayetteville, Ark.). The IsoTherming Hydroprocessing Technology differs from other hydrotreating processes in that hydrogen is dissolved in the liquid feed before the liquid enters the reactor, so the reactors are operated liquid-full, thus avoiding the usual high volume of H2 in the vapor phase. Also, a stream of hydrotreated liquid, containing unused H2, is recycled while still at the reaction pressure and mixed with fresh feed.
While conventional hydrotreating requires a large excess of gaseous H2 that must be compressed, recycled and recombined with fresh feed, IsoTherming needs only a small make-up of gaseous H2, says Scott Webster, technical development manager for DuPont Clean Fuel Technologies (Leawood, Kan.). The process uses conventional catalysts and operates under standard hydrotreating conditions — approximately 550–680°F, and from about 1,200 psi for ultra-low-sulfur diesel fuel (ULSD) to 2,000 psi for hydrocracking. In a revamp, the process can be used to augment the capacity of a conventional hydrotreater by using the existing reactor as a second reactor (flowsheet).
The capital cost of an IsoTherming plant is about 30–40% below that of a conventional plant for ULSD and 50% lower for hydrocracking, says Webster. The savings are achieved mainly from the use of smaller reactors and by eliminating the recycle gas compressor and recycle gas-treating equipment. Operating costs are 20–25% lower, the principal savings being in energy costs for the recycle compressor and lower catalyst consumption.
The first commercial licensor of the process was Giant Refining Co., now Western Refining (El Paso, Tex.). The company put a 12,000-bbl/d ULSD plant onstream at its Yorktown, Va., refinery in 2006 and has also installed two 5,000-bbl/d units at its refinery in Gallup, N.M. DuPont is now doing basic engineering on three grassroots projects for mild hydrocracking of FCC gasoil feed, and one ULSD revamp.