PROCESS FOR HYDROTREATING A HYDROCARBON OIL

A hydrocarbon oil is hydrotreated in a process employing at least a first and a second reactor vessel, which process comprises: (i) contacting the hydrocarbon oil in the first reactor vessel at elevated temperature and pressure with a hydrotreating catalyst in the presence of a hydrogen-containing gas, thereby consuming hydrogen; (ii) separating the effluent of step (i) into partly hydrotreated hydrocarbon oil and contaminated hydrogen containing gas using a stripping column employing used hydrogen-containing gas as stripping gas; (iii) contacting partly hydrotreated hydrocarbon oil obtained in step (ii) in the second reactor vessel at elevated temperature and pressure with a hydrotreating catalyst in the presence of clean hydrogen-containing gas, thereby consuming hydrogen, wherein at least 80% of the hydrogen consumed in steps (i) and (iii) is supplemented by additional clean hydrogen-containing gas fed to the second reactor; (iv) separating the product from step (iii) in the second reactor vessel into a hydrotreated hydrocarbon oil and used hydrogen-containing gas, which hydrotreated hydrocarbon oil can be recovered as product and, (v) transporting at least a portion of used hydrogen-containing gas obtained in step (iv) to step (ii) for use as stripping gas.