Residue desulfurization is a high-pressure catalytic hydrotreating process. Chevron Lummus Global (CLG), a joint venture between Lummus Technology and Chevron U.S.A., Inc., offers several proven technologies for residuum desulfurization.CLG’s atmospheric residuum desulfurization (RDS) and vacuum residuum desulfurization (VRDS) technologies produce low sulfur fuel oil or feedstock for residuum FCC units. Today CLG-licensed RDS units account for more than 80% of all units worldwide. The possible feeds for RDS/VRDS are atmospheric and vacuum residue, vacuum gas oil, heavy coker gas oil or deasphalted oil. Residual product can be low sulfur fuel oil (0.3 – 1 wt.% sulfur) or feed to the RFCC unit, hydrocrackers or delayed coking units. With high metals residue feeds, an Upflow Reactor (UFR®) is used upstream of the VRDS unit to extend catalyst run length. Still higher metals content requires the use of OCR® (Onstream Catalyst Replacement) technology. Both UFR and OCR are licensed by CLG.